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1 | =encoding utf-8 |
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2 | |
1 | =head1 NAME |
3 | =head1 NAME |
2 | |
4 | |
3 | libev - a high performance full-featured event loop written in C |
5 | libev - a high performance full-featured event loop written in C |
4 | |
6 | |
5 | =head1 SYNOPSIS |
7 | =head1 SYNOPSIS |
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26 | puts ("stdin ready"); |
28 | puts ("stdin ready"); |
27 | // for one-shot events, one must manually stop the watcher |
29 | // for one-shot events, one must manually stop the watcher |
28 | // with its corresponding stop function. |
30 | // with its corresponding stop function. |
29 | ev_io_stop (EV_A_ w); |
31 | ev_io_stop (EV_A_ w); |
30 | |
32 | |
31 | // this causes all nested ev_loop's to stop iterating |
33 | // this causes all nested ev_run's to stop iterating |
32 | ev_unloop (EV_A_ EVUNLOOP_ALL); |
34 | ev_break (EV_A_ EVBREAK_ALL); |
33 | } |
35 | } |
34 | |
36 | |
35 | // another callback, this time for a time-out |
37 | // another callback, this time for a time-out |
36 | static void |
38 | static void |
37 | timeout_cb (EV_P_ ev_timer *w, int revents) |
39 | timeout_cb (EV_P_ ev_timer *w, int revents) |
38 | { |
40 | { |
39 | puts ("timeout"); |
41 | puts ("timeout"); |
40 | // this causes the innermost ev_loop to stop iterating |
42 | // this causes the innermost ev_run to stop iterating |
41 | ev_unloop (EV_A_ EVUNLOOP_ONE); |
43 | ev_break (EV_A_ EVBREAK_ONE); |
42 | } |
44 | } |
43 | |
45 | |
44 | int |
46 | int |
45 | main (void) |
47 | main (void) |
46 | { |
48 | { |
47 | // use the default event loop unless you have special needs |
49 | // use the default event loop unless you have special needs |
48 | struct ev_loop *loop = ev_default_loop (0); |
50 | struct ev_loop *loop = EV_DEFAULT; |
49 | |
51 | |
50 | // initialise an io watcher, then start it |
52 | // initialise an io watcher, then start it |
51 | // this one will watch for stdin to become readable |
53 | // this one will watch for stdin to become readable |
52 | ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
54 | ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
53 | ev_io_start (loop, &stdin_watcher); |
55 | ev_io_start (loop, &stdin_watcher); |
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56 | // simple non-repeating 5.5 second timeout |
58 | // simple non-repeating 5.5 second timeout |
57 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
59 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
58 | ev_timer_start (loop, &timeout_watcher); |
60 | ev_timer_start (loop, &timeout_watcher); |
59 | |
61 | |
60 | // now wait for events to arrive |
62 | // now wait for events to arrive |
61 | ev_loop (loop, 0); |
63 | ev_run (loop, 0); |
62 | |
64 | |
63 | // unloop was called, so exit |
65 | // break was called, so exit |
64 | return 0; |
66 | return 0; |
65 | } |
67 | } |
66 | |
68 | |
67 | =head1 ABOUT THIS DOCUMENT |
69 | =head1 ABOUT THIS DOCUMENT |
68 | |
70 | |
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75 | While this document tries to be as complete as possible in documenting |
77 | While this document tries to be as complete as possible in documenting |
76 | libev, its usage and the rationale behind its design, it is not a tutorial |
78 | libev, its usage and the rationale behind its design, it is not a tutorial |
77 | on event-based programming, nor will it introduce event-based programming |
79 | on event-based programming, nor will it introduce event-based programming |
78 | with libev. |
80 | with libev. |
79 | |
81 | |
80 | Familarity with event based programming techniques in general is assumed |
82 | Familiarity with event based programming techniques in general is assumed |
81 | throughout this document. |
83 | throughout this document. |
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84 | |
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85 | =head1 WHAT TO READ WHEN IN A HURRY |
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86 | |
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87 | This manual tries to be very detailed, but unfortunately, this also makes |
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88 | it very long. If you just want to know the basics of libev, I suggest |
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89 | reading L</ANATOMY OF A WATCHER>, then the L</EXAMPLE PROGRAM> above and |
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90 | look up the missing functions in L</GLOBAL FUNCTIONS> and the C<ev_io> and |
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91 | C<ev_timer> sections in L</WATCHER TYPES>. |
82 | |
92 | |
83 | =head1 ABOUT LIBEV |
93 | =head1 ABOUT LIBEV |
84 | |
94 | |
85 | Libev is an event loop: you register interest in certain events (such as a |
95 | Libev is an event loop: you register interest in certain events (such as a |
86 | file descriptor being readable or a timeout occurring), and it will manage |
96 | file descriptor being readable or a timeout occurring), and it will manage |
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95 | details of the event, and then hand it over to libev by I<starting> the |
105 | details of the event, and then hand it over to libev by I<starting> the |
96 | watcher. |
106 | watcher. |
97 | |
107 | |
98 | =head2 FEATURES |
108 | =head2 FEATURES |
99 | |
109 | |
100 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
110 | Libev supports C<select>, C<poll>, the Linux-specific aio and C<epoll> |
101 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
111 | interfaces, the BSD-specific C<kqueue> and the Solaris-specific event port |
102 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
112 | mechanisms for file descriptor events (C<ev_io>), the Linux C<inotify> |
103 | (for C<ev_stat>), relative timers (C<ev_timer>), absolute timers |
113 | interface (for C<ev_stat>), Linux eventfd/signalfd (for faster and cleaner |
104 | with customised rescheduling (C<ev_periodic>), synchronous signals |
114 | inter-thread wakeup (C<ev_async>)/signal handling (C<ev_signal>)) relative |
105 | (C<ev_signal>), process status change events (C<ev_child>), and event |
115 | timers (C<ev_timer>), absolute timers with customised rescheduling |
106 | watchers dealing with the event loop mechanism itself (C<ev_idle>, |
116 | (C<ev_periodic>), synchronous signals (C<ev_signal>), process status |
107 | C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as |
117 | change events (C<ev_child>), and event watchers dealing with the event |
108 | file watchers (C<ev_stat>) and even limited support for fork events |
118 | loop mechanism itself (C<ev_idle>, C<ev_embed>, C<ev_prepare> and |
109 | (C<ev_fork>). |
119 | C<ev_check> watchers) as well as file watchers (C<ev_stat>) and even |
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120 | limited support for fork events (C<ev_fork>). |
110 | |
121 | |
111 | It also is quite fast (see this |
122 | It also is quite fast (see this |
112 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
123 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
113 | for example). |
124 | for example). |
114 | |
125 | |
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117 | Libev is very configurable. In this manual the default (and most common) |
128 | Libev is very configurable. In this manual the default (and most common) |
118 | configuration will be described, which supports multiple event loops. For |
129 | configuration will be described, which supports multiple event loops. For |
119 | more info about various configuration options please have a look at |
130 | more info about various configuration options please have a look at |
120 | B<EMBED> section in this manual. If libev was configured without support |
131 | B<EMBED> section in this manual. If libev was configured without support |
121 | for multiple event loops, then all functions taking an initial argument of |
132 | for multiple event loops, then all functions taking an initial argument of |
122 | name C<loop> (which is always of type C<ev_loop *>) will not have |
133 | name C<loop> (which is always of type C<struct ev_loop *>) will not have |
123 | this argument. |
134 | this argument. |
124 | |
135 | |
125 | =head2 TIME REPRESENTATION |
136 | =head2 TIME REPRESENTATION |
126 | |
137 | |
127 | Libev represents time as a single floating point number, representing |
138 | Libev represents time as a single floating point number, representing |
128 | the (fractional) number of seconds since the (POSIX) epoch (somewhere |
139 | the (fractional) number of seconds since the (POSIX) epoch (in practice |
129 | near the beginning of 1970, details are complicated, don't ask). This |
140 | somewhere near the beginning of 1970, details are complicated, don't |
130 | type is called C<ev_tstamp>, which is what you should use too. It usually |
141 | ask). This type is called C<ev_tstamp>, which is what you should use |
131 | aliases to the C<double> type in C. When you need to do any calculations |
142 | too. It usually aliases to the C<double> type in C. When you need to do |
132 | on it, you should treat it as some floating point value. Unlike the name |
143 | any calculations on it, you should treat it as some floating point value. |
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144 | |
133 | component C<stamp> might indicate, it is also used for time differences |
145 | Unlike the name component C<stamp> might indicate, it is also used for |
134 | throughout libev. |
146 | time differences (e.g. delays) throughout libev. |
135 | |
147 | |
136 | =head1 ERROR HANDLING |
148 | =head1 ERROR HANDLING |
137 | |
149 | |
138 | Libev knows three classes of errors: operating system errors, usage errors |
150 | Libev knows three classes of errors: operating system errors, usage errors |
139 | and internal errors (bugs). |
151 | and internal errors (bugs). |
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147 | When libev detects a usage error such as a negative timer interval, then |
159 | When libev detects a usage error such as a negative timer interval, then |
148 | it will print a diagnostic message and abort (via the C<assert> mechanism, |
160 | it will print a diagnostic message and abort (via the C<assert> mechanism, |
149 | so C<NDEBUG> will disable this checking): these are programming errors in |
161 | so C<NDEBUG> will disable this checking): these are programming errors in |
150 | the libev caller and need to be fixed there. |
162 | the libev caller and need to be fixed there. |
151 | |
163 | |
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164 | Via the C<EV_FREQUENT> macro you can compile in and/or enable extensive |
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165 | consistency checking code inside libev that can be used to check for |
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166 | internal inconsistencies, suually caused by application bugs. |
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167 | |
152 | Libev also has a few internal error-checking C<assert>ions, and also has |
168 | Libev also has a few internal error-checking C<assert>ions. These do not |
153 | extensive consistency checking code. These do not trigger under normal |
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154 | circumstances, as they indicate either a bug in libev or worse. |
169 | trigger under normal circumstances, as they indicate either a bug in libev |
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170 | or worse. |
155 | |
171 | |
156 | |
172 | |
157 | =head1 GLOBAL FUNCTIONS |
173 | =head1 GLOBAL FUNCTIONS |
158 | |
174 | |
159 | These functions can be called anytime, even before initialising the |
175 | These functions can be called anytime, even before initialising the |
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163 | |
179 | |
164 | =item ev_tstamp ev_time () |
180 | =item ev_tstamp ev_time () |
165 | |
181 | |
166 | Returns the current time as libev would use it. Please note that the |
182 | Returns the current time as libev would use it. Please note that the |
167 | C<ev_now> function is usually faster and also often returns the timestamp |
183 | C<ev_now> function is usually faster and also often returns the timestamp |
168 | you actually want to know. |
184 | you actually want to know. Also interesting is the combination of |
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185 | C<ev_now_update> and C<ev_now>. |
169 | |
186 | |
170 | =item ev_sleep (ev_tstamp interval) |
187 | =item ev_sleep (ev_tstamp interval) |
171 | |
188 | |
172 | Sleep for the given interval: The current thread will be blocked until |
189 | Sleep for the given interval: The current thread will be blocked |
173 | either it is interrupted or the given time interval has passed. Basically |
190 | until either it is interrupted or the given time interval has |
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191 | passed (approximately - it might return a bit earlier even if not |
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192 | interrupted). Returns immediately if C<< interval <= 0 >>. |
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193 | |
174 | this is a sub-second-resolution C<sleep ()>. |
194 | Basically this is a sub-second-resolution C<sleep ()>. |
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195 | |
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196 | The range of the C<interval> is limited - libev only guarantees to work |
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197 | with sleep times of up to one day (C<< interval <= 86400 >>). |
175 | |
198 | |
176 | =item int ev_version_major () |
199 | =item int ev_version_major () |
177 | |
200 | |
178 | =item int ev_version_minor () |
201 | =item int ev_version_minor () |
179 | |
202 | |
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190 | as this indicates an incompatible change. Minor versions are usually |
213 | as this indicates an incompatible change. Minor versions are usually |
191 | compatible to older versions, so a larger minor version alone is usually |
214 | compatible to older versions, so a larger minor version alone is usually |
192 | not a problem. |
215 | not a problem. |
193 | |
216 | |
194 | Example: Make sure we haven't accidentally been linked against the wrong |
217 | Example: Make sure we haven't accidentally been linked against the wrong |
195 | version. |
218 | version (note, however, that this will not detect other ABI mismatches, |
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219 | such as LFS or reentrancy). |
196 | |
220 | |
197 | assert (("libev version mismatch", |
221 | assert (("libev version mismatch", |
198 | ev_version_major () == EV_VERSION_MAJOR |
222 | ev_version_major () == EV_VERSION_MAJOR |
199 | && ev_version_minor () >= EV_VERSION_MINOR)); |
223 | && ev_version_minor () >= EV_VERSION_MINOR)); |
200 | |
224 | |
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211 | assert (("sorry, no epoll, no sex", |
235 | assert (("sorry, no epoll, no sex", |
212 | ev_supported_backends () & EVBACKEND_EPOLL)); |
236 | ev_supported_backends () & EVBACKEND_EPOLL)); |
213 | |
237 | |
214 | =item unsigned int ev_recommended_backends () |
238 | =item unsigned int ev_recommended_backends () |
215 | |
239 | |
216 | Return the set of all backends compiled into this binary of libev and also |
240 | Return the set of all backends compiled into this binary of libev and |
217 | recommended for this platform. This set is often smaller than the one |
241 | also recommended for this platform, meaning it will work for most file |
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242 | descriptor types. This set is often smaller than the one returned by |
218 | returned by C<ev_supported_backends>, as for example kqueue is broken on |
243 | C<ev_supported_backends>, as for example kqueue is broken on most BSDs |
219 | most BSDs and will not be auto-detected unless you explicitly request it |
244 | and will not be auto-detected unless you explicitly request it (assuming |
220 | (assuming you know what you are doing). This is the set of backends that |
245 | you know what you are doing). This is the set of backends that libev will |
221 | libev will probe for if you specify no backends explicitly. |
246 | probe for if you specify no backends explicitly. |
222 | |
247 | |
223 | =item unsigned int ev_embeddable_backends () |
248 | =item unsigned int ev_embeddable_backends () |
224 | |
249 | |
225 | Returns the set of backends that are embeddable in other event loops. This |
250 | Returns the set of backends that are embeddable in other event loops. This |
226 | is the theoretical, all-platform, value. To find which backends |
251 | value is platform-specific but can include backends not available on the |
227 | might be supported on the current system, you would need to look at |
252 | current system. To find which embeddable backends might be supported on |
228 | C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for |
253 | the current system, you would need to look at C<ev_embeddable_backends () |
229 | recommended ones. |
254 | & ev_supported_backends ()>, likewise for recommended ones. |
230 | |
255 | |
231 | See the description of C<ev_embed> watchers for more info. |
256 | See the description of C<ev_embed> watchers for more info. |
232 | |
257 | |
233 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT] |
258 | =item ev_set_allocator (void *(*cb)(void *ptr, long size) throw ()) |
234 | |
259 | |
235 | Sets the allocation function to use (the prototype is similar - the |
260 | Sets the allocation function to use (the prototype is similar - the |
236 | semantics are identical to the C<realloc> C89/SuS/POSIX function). It is |
261 | semantics are identical to the C<realloc> C89/SuS/POSIX function). It is |
237 | used to allocate and free memory (no surprises here). If it returns zero |
262 | used to allocate and free memory (no surprises here). If it returns zero |
238 | when memory needs to be allocated (C<size != 0>), the library might abort |
263 | when memory needs to be allocated (C<size != 0>), the library might abort |
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244 | |
269 | |
245 | You could override this function in high-availability programs to, say, |
270 | You could override this function in high-availability programs to, say, |
246 | free some memory if it cannot allocate memory, to use a special allocator, |
271 | free some memory if it cannot allocate memory, to use a special allocator, |
247 | or even to sleep a while and retry until some memory is available. |
272 | or even to sleep a while and retry until some memory is available. |
248 | |
273 | |
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274 | Example: The following is the C<realloc> function that libev itself uses |
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275 | which should work with C<realloc> and C<free> functions of all kinds and |
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276 | is probably a good basis for your own implementation. |
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277 | |
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278 | static void * |
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279 | ev_realloc_emul (void *ptr, long size) EV_NOEXCEPT |
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280 | { |
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281 | if (size) |
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282 | return realloc (ptr, size); |
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283 | |
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284 | free (ptr); |
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285 | return 0; |
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286 | } |
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287 | |
249 | Example: Replace the libev allocator with one that waits a bit and then |
288 | Example: Replace the libev allocator with one that waits a bit and then |
250 | retries (example requires a standards-compliant C<realloc>). |
289 | retries. |
251 | |
290 | |
252 | static void * |
291 | static void * |
253 | persistent_realloc (void *ptr, size_t size) |
292 | persistent_realloc (void *ptr, size_t size) |
254 | { |
293 | { |
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294 | if (!size) |
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295 | { |
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296 | free (ptr); |
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297 | return 0; |
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298 | } |
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299 | |
255 | for (;;) |
300 | for (;;) |
256 | { |
301 | { |
257 | void *newptr = realloc (ptr, size); |
302 | void *newptr = realloc (ptr, size); |
258 | |
303 | |
259 | if (newptr) |
304 | if (newptr) |
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264 | } |
309 | } |
265 | |
310 | |
266 | ... |
311 | ... |
267 | ev_set_allocator (persistent_realloc); |
312 | ev_set_allocator (persistent_realloc); |
268 | |
313 | |
269 | =item ev_set_syserr_cb (void (*cb)(const char *msg)); [NOT REENTRANT] |
314 | =item ev_set_syserr_cb (void (*cb)(const char *msg) throw ()) |
270 | |
315 | |
271 | Set the callback function to call on a retryable system call error (such |
316 | Set the callback function to call on a retryable system call error (such |
272 | as failed select, poll, epoll_wait). The message is a printable string |
317 | as failed select, poll, epoll_wait). The message is a printable string |
273 | indicating the system call or subsystem causing the problem. If this |
318 | indicating the system call or subsystem causing the problem. If this |
274 | callback is set, then libev will expect it to remedy the situation, no |
319 | callback is set, then libev will expect it to remedy the situation, no |
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286 | } |
331 | } |
287 | |
332 | |
288 | ... |
333 | ... |
289 | ev_set_syserr_cb (fatal_error); |
334 | ev_set_syserr_cb (fatal_error); |
290 | |
335 | |
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336 | =item ev_feed_signal (int signum) |
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337 | |
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338 | This function can be used to "simulate" a signal receive. It is completely |
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339 | safe to call this function at any time, from any context, including signal |
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340 | handlers or random threads. |
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341 | |
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342 | Its main use is to customise signal handling in your process, especially |
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343 | in the presence of threads. For example, you could block signals |
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344 | by default in all threads (and specifying C<EVFLAG_NOSIGMASK> when |
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345 | creating any loops), and in one thread, use C<sigwait> or any other |
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346 | mechanism to wait for signals, then "deliver" them to libev by calling |
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347 | C<ev_feed_signal>. |
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348 | |
291 | =back |
349 | =back |
292 | |
350 | |
293 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
351 | =head1 FUNCTIONS CONTROLLING EVENT LOOPS |
294 | |
352 | |
295 | An event loop is described by a C<struct ev_loop *> (the C<struct> |
353 | An event loop is described by a C<struct ev_loop *> (the C<struct> is |
296 | is I<not> optional in this case, as there is also an C<ev_loop> |
354 | I<not> optional in this case unless libev 3 compatibility is disabled, as |
297 | I<function>). |
355 | libev 3 had an C<ev_loop> function colliding with the struct name). |
298 | |
356 | |
299 | The library knows two types of such loops, the I<default> loop, which |
357 | The library knows two types of such loops, the I<default> loop, which |
300 | supports signals and child events, and dynamically created loops which do |
358 | supports child process events, and dynamically created event loops which |
301 | not. |
359 | do not. |
302 | |
360 | |
303 | =over 4 |
361 | =over 4 |
304 | |
362 | |
305 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
363 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
306 | |
364 | |
307 | This will initialise the default event loop if it hasn't been initialised |
365 | This returns the "default" event loop object, which is what you should |
308 | yet and return it. If the default loop could not be initialised, returns |
366 | normally use when you just need "the event loop". Event loop objects and |
309 | false. If it already was initialised it simply returns it (and ignores the |
367 | the C<flags> parameter are described in more detail in the entry for |
310 | flags. If that is troubling you, check C<ev_backend ()> afterwards). |
368 | C<ev_loop_new>. |
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369 | |
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370 | If the default loop is already initialised then this function simply |
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371 | returns it (and ignores the flags. If that is troubling you, check |
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372 | C<ev_backend ()> afterwards). Otherwise it will create it with the given |
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373 | flags, which should almost always be C<0>, unless the caller is also the |
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374 | one calling C<ev_run> or otherwise qualifies as "the main program". |
311 | |
375 | |
312 | If you don't know what event loop to use, use the one returned from this |
376 | If you don't know what event loop to use, use the one returned from this |
313 | function. |
377 | function (or via the C<EV_DEFAULT> macro). |
314 | |
378 | |
315 | Note that this function is I<not> thread-safe, so if you want to use it |
379 | Note that this function is I<not> thread-safe, so if you want to use it |
316 | from multiple threads, you have to lock (note also that this is unlikely, |
380 | from multiple threads, you have to employ some kind of mutex (note also |
317 | as loops cannot be shared easily between threads anyway). |
381 | that this case is unlikely, as loops cannot be shared easily between |
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382 | threads anyway). |
318 | |
383 | |
319 | The default loop is the only loop that can handle C<ev_signal> and |
384 | The default loop is the only loop that can handle C<ev_child> watchers, |
320 | C<ev_child> watchers, and to do this, it always registers a handler |
385 | and to do this, it always registers a handler for C<SIGCHLD>. If this is |
321 | for C<SIGCHLD>. If this is a problem for your application you can either |
386 | a problem for your application you can either create a dynamic loop with |
322 | create a dynamic loop with C<ev_loop_new> that doesn't do that, or you |
387 | C<ev_loop_new> which doesn't do that, or you can simply overwrite the |
323 | can simply overwrite the C<SIGCHLD> signal handler I<after> calling |
388 | C<SIGCHLD> signal handler I<after> calling C<ev_default_init>. |
324 | C<ev_default_init>. |
389 | |
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390 | Example: This is the most typical usage. |
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391 | |
|
|
392 | if (!ev_default_loop (0)) |
|
|
393 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
|
|
394 | |
|
|
395 | Example: Restrict libev to the select and poll backends, and do not allow |
|
|
396 | environment settings to be taken into account: |
|
|
397 | |
|
|
398 | ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
|
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399 | |
|
|
400 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
|
|
401 | |
|
|
402 | This will create and initialise a new event loop object. If the loop |
|
|
403 | could not be initialised, returns false. |
|
|
404 | |
|
|
405 | This function is thread-safe, and one common way to use libev with |
|
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406 | threads is indeed to create one loop per thread, and using the default |
|
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407 | loop in the "main" or "initial" thread. |
325 | |
408 | |
326 | The flags argument can be used to specify special behaviour or specific |
409 | The flags argument can be used to specify special behaviour or specific |
327 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
410 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
328 | |
411 | |
329 | The following flags are supported: |
412 | The following flags are supported: |
… | |
… | |
339 | |
422 | |
340 | If this flag bit is or'ed into the flag value (or the program runs setuid |
423 | If this flag bit is or'ed into the flag value (or the program runs setuid |
341 | or setgid) then libev will I<not> look at the environment variable |
424 | or setgid) then libev will I<not> look at the environment variable |
342 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
425 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
343 | override the flags completely if it is found in the environment. This is |
426 | override the flags completely if it is found in the environment. This is |
344 | useful to try out specific backends to test their performance, or to work |
427 | useful to try out specific backends to test their performance, to work |
345 | around bugs. |
428 | around bugs, or to make libev threadsafe (accessing environment variables |
|
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429 | cannot be done in a threadsafe way, but usually it works if no other |
|
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430 | thread modifies them). |
346 | |
431 | |
347 | =item C<EVFLAG_FORKCHECK> |
432 | =item C<EVFLAG_FORKCHECK> |
348 | |
433 | |
349 | Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after |
434 | Instead of calling C<ev_loop_fork> manually after a fork, you can also |
350 | a fork, you can also make libev check for a fork in each iteration by |
435 | make libev check for a fork in each iteration by enabling this flag. |
351 | enabling this flag. |
|
|
352 | |
436 | |
353 | This works by calling C<getpid ()> on every iteration of the loop, |
437 | This works by calling C<getpid ()> on every iteration of the loop, |
354 | and thus this might slow down your event loop if you do a lot of loop |
438 | and thus this might slow down your event loop if you do a lot of loop |
355 | iterations and little real work, but is usually not noticeable (on my |
439 | iterations and little real work, but is usually not noticeable (on my |
356 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence |
440 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn |
357 | without a system call and thus I<very> fast, but my GNU/Linux system also has |
441 | sequence without a system call and thus I<very> fast, but my GNU/Linux |
358 | C<pthread_atfork> which is even faster). |
442 | system also has C<pthread_atfork> which is even faster). (Update: glibc |
|
|
443 | versions 2.25 apparently removed the C<getpid> optimisation again). |
359 | |
444 | |
360 | The big advantage of this flag is that you can forget about fork (and |
445 | The big advantage of this flag is that you can forget about fork (and |
361 | forget about forgetting to tell libev about forking) when you use this |
446 | forget about forgetting to tell libev about forking, although you still |
362 | flag. |
447 | have to ignore C<SIGPIPE>) when you use this flag. |
363 | |
448 | |
364 | This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS> |
449 | This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS> |
365 | environment variable. |
450 | environment variable. |
|
|
451 | |
|
|
452 | =item C<EVFLAG_NOINOTIFY> |
|
|
453 | |
|
|
454 | When this flag is specified, then libev will not attempt to use the |
|
|
455 | I<inotify> API for its C<ev_stat> watchers. Apart from debugging and |
|
|
456 | testing, this flag can be useful to conserve inotify file descriptors, as |
|
|
457 | otherwise each loop using C<ev_stat> watchers consumes one inotify handle. |
|
|
458 | |
|
|
459 | =item C<EVFLAG_SIGNALFD> |
|
|
460 | |
|
|
461 | When this flag is specified, then libev will attempt to use the |
|
|
462 | I<signalfd> API for its C<ev_signal> (and C<ev_child>) watchers. This API |
|
|
463 | delivers signals synchronously, which makes it both faster and might make |
|
|
464 | it possible to get the queued signal data. It can also simplify signal |
|
|
465 | handling with threads, as long as you properly block signals in your |
|
|
466 | threads that are not interested in handling them. |
|
|
467 | |
|
|
468 | Signalfd will not be used by default as this changes your signal mask, and |
|
|
469 | there are a lot of shoddy libraries and programs (glib's threadpool for |
|
|
470 | example) that can't properly initialise their signal masks. |
|
|
471 | |
|
|
472 | =item C<EVFLAG_NOSIGMASK> |
|
|
473 | |
|
|
474 | When this flag is specified, then libev will avoid to modify the signal |
|
|
475 | mask. Specifically, this means you have to make sure signals are unblocked |
|
|
476 | when you want to receive them. |
|
|
477 | |
|
|
478 | This behaviour is useful when you want to do your own signal handling, or |
|
|
479 | want to handle signals only in specific threads and want to avoid libev |
|
|
480 | unblocking the signals. |
|
|
481 | |
|
|
482 | It's also required by POSIX in a threaded program, as libev calls |
|
|
483 | C<sigprocmask>, whose behaviour is officially unspecified. |
|
|
484 | |
|
|
485 | =item C<EVFLAG_NOTIMERFD> |
|
|
486 | |
|
|
487 | When this flag is specified, the libev will avoid using a C<timerfd> to |
|
|
488 | detect time jumps. It will still be able to detect time jumps, but takes |
|
|
489 | longer and has a lower accuracy in doing so, but saves a file descriptor |
|
|
490 | per loop. |
|
|
491 | |
|
|
492 | The current implementation only tries to use a C<timerfd> when the first |
|
|
493 | C<ev_periodic> watcher is started and falls back on other methods if it |
|
|
494 | cannot be created, but this behaviour might change in the future. |
366 | |
495 | |
367 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
496 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
368 | |
497 | |
369 | This is your standard select(2) backend. Not I<completely> standard, as |
498 | This is your standard select(2) backend. Not I<completely> standard, as |
370 | libev tries to roll its own fd_set with no limits on the number of fds, |
499 | libev tries to roll its own fd_set with no limits on the number of fds, |
… | |
… | |
395 | This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and |
524 | This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and |
396 | C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>. |
525 | C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>. |
397 | |
526 | |
398 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
527 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
399 | |
528 | |
|
|
529 | Use the Linux-specific epoll(7) interface (for both pre- and post-2.6.9 |
|
|
530 | kernels). |
|
|
531 | |
400 | For few fds, this backend is a bit little slower than poll and select, |
532 | For few fds, this backend is a bit little slower than poll and select, but |
401 | but it scales phenomenally better. While poll and select usually scale |
533 | it scales phenomenally better. While poll and select usually scale like |
402 | like O(total_fds) where n is the total number of fds (or the highest fd), |
534 | O(total_fds) where total_fds is the total number of fds (or the highest |
403 | epoll scales either O(1) or O(active_fds). |
535 | fd), epoll scales either O(1) or O(active_fds). |
404 | |
536 | |
405 | The epoll mechanism deserves honorable mention as the most misdesigned |
537 | The epoll mechanism deserves honorable mention as the most misdesigned |
406 | of the more advanced event mechanisms: mere annoyances include silently |
538 | of the more advanced event mechanisms: mere annoyances include silently |
407 | dropping file descriptors, requiring a system call per change per file |
539 | dropping file descriptors, requiring a system call per change per file |
408 | descriptor (and unnecessary guessing of parameters), problems with dup and |
540 | descriptor (and unnecessary guessing of parameters), problems with dup, |
|
|
541 | returning before the timeout value, resulting in additional iterations |
|
|
542 | (and only giving 5ms accuracy while select on the same platform gives |
409 | so on. The biggest issue is fork races, however - if a program forks then |
543 | 0.1ms) and so on. The biggest issue is fork races, however - if a program |
410 | I<both> parent and child process have to recreate the epoll set, which can |
544 | forks then I<both> parent and child process have to recreate the epoll |
411 | take considerable time (one syscall per file descriptor) and is of course |
545 | set, which can take considerable time (one syscall per file descriptor) |
412 | hard to detect. |
546 | and is of course hard to detect. |
413 | |
547 | |
414 | Epoll is also notoriously buggy - embedding epoll fds I<should> work, but |
548 | Epoll is also notoriously buggy - embedding epoll fds I<should> work, |
415 | of course I<doesn't>, and epoll just loves to report events for totally |
549 | but of course I<doesn't>, and epoll just loves to report events for |
416 | I<different> file descriptors (even already closed ones, so one cannot |
550 | totally I<different> file descriptors (even already closed ones, so |
417 | even remove them from the set) than registered in the set (especially |
551 | one cannot even remove them from the set) than registered in the set |
418 | on SMP systems). Libev tries to counter these spurious notifications by |
552 | (especially on SMP systems). Libev tries to counter these spurious |
419 | employing an additional generation counter and comparing that against the |
553 | notifications by employing an additional generation counter and comparing |
420 | events to filter out spurious ones, recreating the set when required. |
554 | that against the events to filter out spurious ones, recreating the set |
|
|
555 | when required. Epoll also erroneously rounds down timeouts, but gives you |
|
|
556 | no way to know when and by how much, so sometimes you have to busy-wait |
|
|
557 | because epoll returns immediately despite a nonzero timeout. And last |
|
|
558 | not least, it also refuses to work with some file descriptors which work |
|
|
559 | perfectly fine with C<select> (files, many character devices...). |
|
|
560 | |
|
|
561 | Epoll is truly the train wreck among event poll mechanisms, a frankenpoll, |
|
|
562 | cobbled together in a hurry, no thought to design or interaction with |
|
|
563 | others. Oh, the pain, will it ever stop... |
421 | |
564 | |
422 | While stopping, setting and starting an I/O watcher in the same iteration |
565 | While stopping, setting and starting an I/O watcher in the same iteration |
423 | will result in some caching, there is still a system call per such |
566 | will result in some caching, there is still a system call per such |
424 | incident (because the same I<file descriptor> could point to a different |
567 | incident (because the same I<file descriptor> could point to a different |
425 | I<file description> now), so its best to avoid that. Also, C<dup ()>'ed |
568 | I<file description> now), so its best to avoid that. Also, C<dup ()>'ed |
… | |
… | |
437 | All this means that, in practice, C<EVBACKEND_SELECT> can be as fast or |
580 | All this means that, in practice, C<EVBACKEND_SELECT> can be as fast or |
438 | faster than epoll for maybe up to a hundred file descriptors, depending on |
581 | faster than epoll for maybe up to a hundred file descriptors, depending on |
439 | the usage. So sad. |
582 | the usage. So sad. |
440 | |
583 | |
441 | While nominally embeddable in other event loops, this feature is broken in |
584 | While nominally embeddable in other event loops, this feature is broken in |
442 | all kernel versions tested so far. |
585 | a lot of kernel revisions, but probably(!) works in current versions. |
443 | |
586 | |
444 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
587 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
445 | C<EVBACKEND_POLL>. |
588 | C<EVBACKEND_POLL>. |
446 | |
589 | |
|
|
590 | =item C<EVBACKEND_LINUXAIO> (value 64, Linux) |
|
|
591 | |
|
|
592 | Use the Linux-specific Linux AIO (I<not> C<< aio(7) >> but C<< |
|
|
593 | io_submit(2) >>) event interface available in post-4.18 kernels (but libev |
|
|
594 | only tries to use it in 4.19+). |
|
|
595 | |
|
|
596 | This is another Linux train wreck of an event interface. |
|
|
597 | |
|
|
598 | If this backend works for you (as of this writing, it was very |
|
|
599 | experimental), it is the best event interface available on Linux and might |
|
|
600 | be well worth enabling it - if it isn't available in your kernel this will |
|
|
601 | be detected and this backend will be skipped. |
|
|
602 | |
|
|
603 | This backend can batch oneshot requests and supports a user-space ring |
|
|
604 | buffer to receive events. It also doesn't suffer from most of the design |
|
|
605 | problems of epoll (such as not being able to remove event sources from |
|
|
606 | the epoll set), and generally sounds too good to be true. Because, this |
|
|
607 | being the Linux kernel, of course it suffers from a whole new set of |
|
|
608 | limitations, forcing you to fall back to epoll, inheriting all its design |
|
|
609 | issues. |
|
|
610 | |
|
|
611 | For one, it is not easily embeddable (but probably could be done using |
|
|
612 | an event fd at some extra overhead). It also is subject to a system wide |
|
|
613 | limit that can be configured in F</proc/sys/fs/aio-max-nr>. If no AIO |
|
|
614 | requests are left, this backend will be skipped during initialisation, and |
|
|
615 | will switch to epoll when the loop is active. |
|
|
616 | |
|
|
617 | Most problematic in practice, however, is that not all file descriptors |
|
|
618 | work with it. For example, in Linux 5.1, TCP sockets, pipes, event fds, |
|
|
619 | files, F</dev/null> and many others are supported, but ttys do not work |
|
|
620 | properly (a known bug that the kernel developers don't care about, see |
|
|
621 | L<https://lore.kernel.org/patchwork/patch/1047453/>), so this is not |
|
|
622 | (yet?) a generic event polling interface. |
|
|
623 | |
|
|
624 | Overall, it seems the Linux developers just don't want it to have a |
|
|
625 | generic event handling mechanism other than C<select> or C<poll>. |
|
|
626 | |
|
|
627 | To work around all these problem, the current version of libev uses its |
|
|
628 | epoll backend as a fallback for file descriptor types that do not work. Or |
|
|
629 | falls back completely to epoll if the kernel acts up. |
|
|
630 | |
|
|
631 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
|
|
632 | C<EVBACKEND_POLL>. |
|
|
633 | |
447 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
634 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
448 | |
635 | |
449 | Kqueue deserves special mention, as at the time of this writing, it |
636 | Kqueue deserves special mention, as at the time this backend was |
450 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
637 | implemented, it was broken on all BSDs except NetBSD (usually it doesn't |
451 | with anything but sockets and pipes, except on Darwin, where of course |
638 | work reliably with anything but sockets and pipes, except on Darwin, |
452 | it's completely useless). Unlike epoll, however, whose brokenness |
639 | where of course it's completely useless). Unlike epoll, however, whose |
453 | is by design, these kqueue bugs can (and eventually will) be fixed |
640 | brokenness is by design, these kqueue bugs can be (and mostly have been) |
454 | without API changes to existing programs. For this reason it's not being |
641 | fixed without API changes to existing programs. For this reason it's not |
455 | "auto-detected" unless you explicitly specify it in the flags (i.e. using |
642 | being "auto-detected" on all platforms unless you explicitly specify it |
456 | C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough) |
643 | in the flags (i.e. using C<EVBACKEND_KQUEUE>) or libev was compiled on a |
457 | system like NetBSD. |
644 | known-to-be-good (-enough) system like NetBSD. |
458 | |
645 | |
459 | You still can embed kqueue into a normal poll or select backend and use it |
646 | You still can embed kqueue into a normal poll or select backend and use it |
460 | only for sockets (after having made sure that sockets work with kqueue on |
647 | only for sockets (after having made sure that sockets work with kqueue on |
461 | the target platform). See C<ev_embed> watchers for more info. |
648 | the target platform). See C<ev_embed> watchers for more info. |
462 | |
649 | |
463 | It scales in the same way as the epoll backend, but the interface to the |
650 | It scales in the same way as the epoll backend, but the interface to the |
464 | kernel is more efficient (which says nothing about its actual speed, of |
651 | kernel is more efficient (which says nothing about its actual speed, of |
465 | course). While stopping, setting and starting an I/O watcher does never |
652 | course). While stopping, setting and starting an I/O watcher does never |
466 | cause an extra system call as with C<EVBACKEND_EPOLL>, it still adds up to |
653 | cause an extra system call as with C<EVBACKEND_EPOLL>, it still adds up to |
467 | two event changes per incident. Support for C<fork ()> is very bad (but |
654 | two event changes per incident. Support for C<fork ()> is very bad (you |
468 | sane, unlike epoll) and it drops fds silently in similarly hard-to-detect |
655 | might have to leak fds on fork, but it's more sane than epoll) and it |
469 | cases |
656 | drops fds silently in similarly hard-to-detect cases. |
470 | |
657 | |
471 | This backend usually performs well under most conditions. |
658 | This backend usually performs well under most conditions. |
472 | |
659 | |
473 | While nominally embeddable in other event loops, this doesn't work |
660 | While nominally embeddable in other event loops, this doesn't work |
474 | everywhere, so you might need to test for this. And since it is broken |
661 | everywhere, so you might need to test for this. And since it is broken |
… | |
… | |
491 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
678 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
492 | |
679 | |
493 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
680 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
494 | it's really slow, but it still scales very well (O(active_fds)). |
681 | it's really slow, but it still scales very well (O(active_fds)). |
495 | |
682 | |
496 | Please note that Solaris event ports can deliver a lot of spurious |
|
|
497 | notifications, so you need to use non-blocking I/O or other means to avoid |
|
|
498 | blocking when no data (or space) is available. |
|
|
499 | |
|
|
500 | While this backend scales well, it requires one system call per active |
683 | While this backend scales well, it requires one system call per active |
501 | file descriptor per loop iteration. For small and medium numbers of file |
684 | file descriptor per loop iteration. For small and medium numbers of file |
502 | descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend |
685 | descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend |
503 | might perform better. |
686 | might perform better. |
504 | |
687 | |
505 | On the positive side, with the exception of the spurious readiness |
688 | On the positive side, this backend actually performed fully to |
506 | notifications, this backend actually performed fully to specification |
|
|
507 | in all tests and is fully embeddable, which is a rare feat among the |
689 | specification in all tests and is fully embeddable, which is a rare feat |
508 | OS-specific backends (I vastly prefer correctness over speed hacks). |
690 | among the OS-specific backends (I vastly prefer correctness over speed |
|
|
691 | hacks). |
|
|
692 | |
|
|
693 | On the negative side, the interface is I<bizarre> - so bizarre that |
|
|
694 | even sun itself gets it wrong in their code examples: The event polling |
|
|
695 | function sometimes returns events to the caller even though an error |
|
|
696 | occurred, but with no indication whether it has done so or not (yes, it's |
|
|
697 | even documented that way) - deadly for edge-triggered interfaces where you |
|
|
698 | absolutely have to know whether an event occurred or not because you have |
|
|
699 | to re-arm the watcher. |
|
|
700 | |
|
|
701 | Fortunately libev seems to be able to work around these idiocies. |
509 | |
702 | |
510 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
703 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
511 | C<EVBACKEND_POLL>. |
704 | C<EVBACKEND_POLL>. |
512 | |
705 | |
513 | =item C<EVBACKEND_ALL> |
706 | =item C<EVBACKEND_ALL> |
514 | |
707 | |
515 | Try all backends (even potentially broken ones that wouldn't be tried |
708 | Try all backends (even potentially broken ones that wouldn't be tried |
516 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
709 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
517 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
710 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
518 | |
711 | |
519 | It is definitely not recommended to use this flag. |
712 | It is definitely not recommended to use this flag, use whatever |
|
|
713 | C<ev_recommended_backends ()> returns, or simply do not specify a backend |
|
|
714 | at all. |
|
|
715 | |
|
|
716 | =item C<EVBACKEND_MASK> |
|
|
717 | |
|
|
718 | Not a backend at all, but a mask to select all backend bits from a |
|
|
719 | C<flags> value, in case you want to mask out any backends from a flags |
|
|
720 | value (e.g. when modifying the C<LIBEV_FLAGS> environment variable). |
520 | |
721 | |
521 | =back |
722 | =back |
522 | |
723 | |
523 | If one or more of these are or'ed into the flags value, then only these |
724 | If one or more of the backend flags are or'ed into the flags value, |
524 | backends will be tried (in the reverse order as listed here). If none are |
725 | then only these backends will be tried (in the reverse order as listed |
525 | specified, all backends in C<ev_recommended_backends ()> will be tried. |
726 | here). If none are specified, all backends in C<ev_recommended_backends |
526 | |
727 | ()> will be tried. |
527 | Example: This is the most typical usage. |
|
|
528 | |
|
|
529 | if (!ev_default_loop (0)) |
|
|
530 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
|
|
531 | |
|
|
532 | Example: Restrict libev to the select and poll backends, and do not allow |
|
|
533 | environment settings to be taken into account: |
|
|
534 | |
|
|
535 | ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
|
|
536 | |
|
|
537 | Example: Use whatever libev has to offer, but make sure that kqueue is |
|
|
538 | used if available (warning, breaks stuff, best use only with your own |
|
|
539 | private event loop and only if you know the OS supports your types of |
|
|
540 | fds): |
|
|
541 | |
|
|
542 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
|
543 | |
|
|
544 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
|
|
545 | |
|
|
546 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
|
|
547 | always distinct from the default loop. Unlike the default loop, it cannot |
|
|
548 | handle signal and child watchers, and attempts to do so will be greeted by |
|
|
549 | undefined behaviour (or a failed assertion if assertions are enabled). |
|
|
550 | |
|
|
551 | Note that this function I<is> thread-safe, and the recommended way to use |
|
|
552 | libev with threads is indeed to create one loop per thread, and using the |
|
|
553 | default loop in the "main" or "initial" thread. |
|
|
554 | |
728 | |
555 | Example: Try to create a event loop that uses epoll and nothing else. |
729 | Example: Try to create a event loop that uses epoll and nothing else. |
556 | |
730 | |
557 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
731 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
558 | if (!epoller) |
732 | if (!epoller) |
559 | fatal ("no epoll found here, maybe it hides under your chair"); |
733 | fatal ("no epoll found here, maybe it hides under your chair"); |
560 | |
734 | |
|
|
735 | Example: Use whatever libev has to offer, but make sure that kqueue is |
|
|
736 | used if available. |
|
|
737 | |
|
|
738 | struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
|
739 | |
|
|
740 | Example: Similarly, on linux, you mgiht want to take advantage of the |
|
|
741 | linux aio backend if possible, but fall back to something else if that |
|
|
742 | isn't available. |
|
|
743 | |
|
|
744 | struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_LINUXAIO); |
|
|
745 | |
561 | =item ev_default_destroy () |
746 | =item ev_loop_destroy (loop) |
562 | |
747 | |
563 | Destroys the default loop again (frees all memory and kernel state |
748 | Destroys an event loop object (frees all memory and kernel state |
564 | etc.). None of the active event watchers will be stopped in the normal |
749 | etc.). None of the active event watchers will be stopped in the normal |
565 | sense, so e.g. C<ev_is_active> might still return true. It is your |
750 | sense, so e.g. C<ev_is_active> might still return true. It is your |
566 | responsibility to either stop all watchers cleanly yourself I<before> |
751 | responsibility to either stop all watchers cleanly yourself I<before> |
567 | calling this function, or cope with the fact afterwards (which is usually |
752 | calling this function, or cope with the fact afterwards (which is usually |
568 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
753 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
… | |
… | |
570 | |
755 | |
571 | Note that certain global state, such as signal state (and installed signal |
756 | Note that certain global state, such as signal state (and installed signal |
572 | handlers), will not be freed by this function, and related watchers (such |
757 | handlers), will not be freed by this function, and related watchers (such |
573 | as signal and child watchers) would need to be stopped manually. |
758 | as signal and child watchers) would need to be stopped manually. |
574 | |
759 | |
575 | In general it is not advisable to call this function except in the |
760 | This function is normally used on loop objects allocated by |
576 | rare occasion where you really need to free e.g. the signal handling |
761 | C<ev_loop_new>, but it can also be used on the default loop returned by |
|
|
762 | C<ev_default_loop>, in which case it is not thread-safe. |
|
|
763 | |
|
|
764 | Note that it is not advisable to call this function on the default loop |
|
|
765 | except in the rare occasion where you really need to free its resources. |
577 | pipe fds. If you need dynamically allocated loops it is better to use |
766 | If you need dynamically allocated loops it is better to use C<ev_loop_new> |
578 | C<ev_loop_new> and C<ev_loop_destroy>). |
767 | and C<ev_loop_destroy>. |
579 | |
768 | |
580 | =item ev_loop_destroy (loop) |
769 | =item ev_loop_fork (loop) |
581 | |
770 | |
582 | Like C<ev_default_destroy>, but destroys an event loop created by an |
|
|
583 | earlier call to C<ev_loop_new>. |
|
|
584 | |
|
|
585 | =item ev_default_fork () |
|
|
586 | |
|
|
587 | This function sets a flag that causes subsequent C<ev_loop> iterations |
771 | This function sets a flag that causes subsequent C<ev_run> iterations |
588 | to reinitialise the kernel state for backends that have one. Despite the |
772 | to reinitialise the kernel state for backends that have one. Despite |
589 | name, you can call it anytime, but it makes most sense after forking, in |
773 | the name, you can call it anytime you are allowed to start or stop |
590 | the child process (or both child and parent, but that again makes little |
774 | watchers (except inside an C<ev_prepare> callback), but it makes most |
591 | sense). You I<must> call it in the child before using any of the libev |
775 | sense after forking, in the child process. You I<must> call it (or use |
592 | functions, and it will only take effect at the next C<ev_loop> iteration. |
776 | C<EVFLAG_FORKCHECK>) in the child before resuming or calling C<ev_run>. |
|
|
777 | |
|
|
778 | In addition, if you want to reuse a loop (via this function or |
|
|
779 | C<EVFLAG_FORKCHECK>), you I<also> have to ignore C<SIGPIPE>. |
|
|
780 | |
|
|
781 | Again, you I<have> to call it on I<any> loop that you want to re-use after |
|
|
782 | a fork, I<even if you do not plan to use the loop in the parent>. This is |
|
|
783 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
|
|
784 | during fork. |
593 | |
785 | |
594 | On the other hand, you only need to call this function in the child |
786 | On the other hand, you only need to call this function in the child |
595 | process if and only if you want to use the event library in the child. If |
787 | process if and only if you want to use the event loop in the child. If |
596 | you just fork+exec, you don't have to call it at all. |
788 | you just fork+exec or create a new loop in the child, you don't have to |
|
|
789 | call it at all (in fact, C<epoll> is so badly broken that it makes a |
|
|
790 | difference, but libev will usually detect this case on its own and do a |
|
|
791 | costly reset of the backend). |
597 | |
792 | |
598 | The function itself is quite fast and it's usually not a problem to call |
793 | The function itself is quite fast and it's usually not a problem to call |
599 | it just in case after a fork. To make this easy, the function will fit in |
794 | it just in case after a fork. |
600 | quite nicely into a call to C<pthread_atfork>: |
|
|
601 | |
795 | |
|
|
796 | Example: Automate calling C<ev_loop_fork> on the default loop when |
|
|
797 | using pthreads. |
|
|
798 | |
|
|
799 | static void |
|
|
800 | post_fork_child (void) |
|
|
801 | { |
|
|
802 | ev_loop_fork (EV_DEFAULT); |
|
|
803 | } |
|
|
804 | |
|
|
805 | ... |
602 | pthread_atfork (0, 0, ev_default_fork); |
806 | pthread_atfork (0, 0, post_fork_child); |
603 | |
|
|
604 | =item ev_loop_fork (loop) |
|
|
605 | |
|
|
606 | Like C<ev_default_fork>, but acts on an event loop created by |
|
|
607 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
|
|
608 | after fork that you want to re-use in the child, and how you do this is |
|
|
609 | entirely your own problem. |
|
|
610 | |
807 | |
611 | =item int ev_is_default_loop (loop) |
808 | =item int ev_is_default_loop (loop) |
612 | |
809 | |
613 | Returns true when the given loop is, in fact, the default loop, and false |
810 | Returns true when the given loop is, in fact, the default loop, and false |
614 | otherwise. |
811 | otherwise. |
615 | |
812 | |
616 | =item unsigned int ev_loop_count (loop) |
813 | =item unsigned int ev_iteration (loop) |
617 | |
814 | |
618 | Returns the count of loop iterations for the loop, which is identical to |
815 | Returns the current iteration count for the event loop, which is identical |
619 | the number of times libev did poll for new events. It starts at C<0> and |
816 | to the number of times libev did poll for new events. It starts at C<0> |
620 | happily wraps around with enough iterations. |
817 | and happily wraps around with enough iterations. |
621 | |
818 | |
622 | This value can sometimes be useful as a generation counter of sorts (it |
819 | This value can sometimes be useful as a generation counter of sorts (it |
623 | "ticks" the number of loop iterations), as it roughly corresponds with |
820 | "ticks" the number of loop iterations), as it roughly corresponds with |
624 | C<ev_prepare> and C<ev_check> calls. |
821 | C<ev_prepare> and C<ev_check> calls - and is incremented between the |
|
|
822 | prepare and check phases. |
625 | |
823 | |
626 | =item unsigned int ev_loop_depth (loop) |
824 | =item unsigned int ev_depth (loop) |
627 | |
825 | |
628 | Returns the number of times C<ev_loop> was entered minus the number of |
826 | Returns the number of times C<ev_run> was entered minus the number of |
629 | times C<ev_loop> was exited, in other words, the recursion depth. |
827 | times C<ev_run> was exited normally, in other words, the recursion depth. |
630 | |
828 | |
631 | Outside C<ev_loop>, this number is zero. In a callback, this number is |
829 | Outside C<ev_run>, this number is zero. In a callback, this number is |
632 | C<1>, unless C<ev_loop> was invoked recursively (or from another thread), |
830 | C<1>, unless C<ev_run> was invoked recursively (or from another thread), |
633 | in which case it is higher. |
831 | in which case it is higher. |
634 | |
832 | |
635 | Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread |
833 | Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread, |
636 | etc.), doesn't count as exit. |
834 | throwing an exception etc.), doesn't count as "exit" - consider this |
|
|
835 | as a hint to avoid such ungentleman-like behaviour unless it's really |
|
|
836 | convenient, in which case it is fully supported. |
637 | |
837 | |
638 | =item unsigned int ev_backend (loop) |
838 | =item unsigned int ev_backend (loop) |
639 | |
839 | |
640 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
840 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
641 | use. |
841 | use. |
… | |
… | |
650 | |
850 | |
651 | =item ev_now_update (loop) |
851 | =item ev_now_update (loop) |
652 | |
852 | |
653 | Establishes the current time by querying the kernel, updating the time |
853 | Establishes the current time by querying the kernel, updating the time |
654 | returned by C<ev_now ()> in the progress. This is a costly operation and |
854 | returned by C<ev_now ()> in the progress. This is a costly operation and |
655 | is usually done automatically within C<ev_loop ()>. |
855 | is usually done automatically within C<ev_run ()>. |
656 | |
856 | |
657 | This function is rarely useful, but when some event callback runs for a |
857 | This function is rarely useful, but when some event callback runs for a |
658 | very long time without entering the event loop, updating libev's idea of |
858 | very long time without entering the event loop, updating libev's idea of |
659 | the current time is a good idea. |
859 | the current time is a good idea. |
660 | |
860 | |
661 | See also L<The special problem of time updates> in the C<ev_timer> section. |
861 | See also L</The special problem of time updates> in the C<ev_timer> section. |
662 | |
862 | |
663 | =item ev_suspend (loop) |
863 | =item ev_suspend (loop) |
664 | |
864 | |
665 | =item ev_resume (loop) |
865 | =item ev_resume (loop) |
666 | |
866 | |
667 | These two functions suspend and resume a loop, for use when the loop is |
867 | These two functions suspend and resume an event loop, for use when the |
668 | not used for a while and timeouts should not be processed. |
868 | loop is not used for a while and timeouts should not be processed. |
669 | |
869 | |
670 | A typical use case would be an interactive program such as a game: When |
870 | A typical use case would be an interactive program such as a game: When |
671 | the user presses C<^Z> to suspend the game and resumes it an hour later it |
871 | the user presses C<^Z> to suspend the game and resumes it an hour later it |
672 | would be best to handle timeouts as if no time had actually passed while |
872 | would be best to handle timeouts as if no time had actually passed while |
673 | the program was suspended. This can be achieved by calling C<ev_suspend> |
873 | the program was suspended. This can be achieved by calling C<ev_suspend> |
… | |
… | |
675 | C<ev_resume> directly afterwards to resume timer processing. |
875 | C<ev_resume> directly afterwards to resume timer processing. |
676 | |
876 | |
677 | Effectively, all C<ev_timer> watchers will be delayed by the time spend |
877 | Effectively, all C<ev_timer> watchers will be delayed by the time spend |
678 | between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers |
878 | between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers |
679 | will be rescheduled (that is, they will lose any events that would have |
879 | will be rescheduled (that is, they will lose any events that would have |
680 | occured while suspended). |
880 | occurred while suspended). |
681 | |
881 | |
682 | After calling C<ev_suspend> you B<must not> call I<any> function on the |
882 | After calling C<ev_suspend> you B<must not> call I<any> function on the |
683 | given loop other than C<ev_resume>, and you B<must not> call C<ev_resume> |
883 | given loop other than C<ev_resume>, and you B<must not> call C<ev_resume> |
684 | without a previous call to C<ev_suspend>. |
884 | without a previous call to C<ev_suspend>. |
685 | |
885 | |
686 | Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the |
886 | Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the |
687 | event loop time (see C<ev_now_update>). |
887 | event loop time (see C<ev_now_update>). |
688 | |
888 | |
689 | =item ev_loop (loop, int flags) |
889 | =item bool ev_run (loop, int flags) |
690 | |
890 | |
691 | Finally, this is it, the event handler. This function usually is called |
891 | Finally, this is it, the event handler. This function usually is called |
692 | after you initialised all your watchers and you want to start handling |
892 | after you have initialised all your watchers and you want to start |
693 | events. |
893 | handling events. It will ask the operating system for any new events, call |
|
|
894 | the watcher callbacks, and then repeat the whole process indefinitely: This |
|
|
895 | is why event loops are called I<loops>. |
694 | |
896 | |
695 | If the flags argument is specified as C<0>, it will not return until |
897 | If the flags argument is specified as C<0>, it will keep handling events |
696 | either no event watchers are active anymore or C<ev_unloop> was called. |
898 | until either no event watchers are active anymore or C<ev_break> was |
|
|
899 | called. |
697 | |
900 | |
|
|
901 | The return value is false if there are no more active watchers (which |
|
|
902 | usually means "all jobs done" or "deadlock"), and true in all other cases |
|
|
903 | (which usually means " you should call C<ev_run> again"). |
|
|
904 | |
698 | Please note that an explicit C<ev_unloop> is usually better than |
905 | Please note that an explicit C<ev_break> is usually better than |
699 | relying on all watchers to be stopped when deciding when a program has |
906 | relying on all watchers to be stopped when deciding when a program has |
700 | finished (especially in interactive programs), but having a program |
907 | finished (especially in interactive programs), but having a program |
701 | that automatically loops as long as it has to and no longer by virtue |
908 | that automatically loops as long as it has to and no longer by virtue |
702 | of relying on its watchers stopping correctly, that is truly a thing of |
909 | of relying on its watchers stopping correctly, that is truly a thing of |
703 | beauty. |
910 | beauty. |
704 | |
911 | |
|
|
912 | This function is I<mostly> exception-safe - you can break out of a |
|
|
913 | C<ev_run> call by calling C<longjmp> in a callback, throwing a C++ |
|
|
914 | exception and so on. This does not decrement the C<ev_depth> value, nor |
|
|
915 | will it clear any outstanding C<EVBREAK_ONE> breaks. |
|
|
916 | |
705 | A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle |
917 | A flags value of C<EVRUN_NOWAIT> will look for new events, will handle |
706 | those events and any already outstanding ones, but will not block your |
918 | those events and any already outstanding ones, but will not wait and |
707 | process in case there are no events and will return after one iteration of |
919 | block your process in case there are no events and will return after one |
708 | the loop. |
920 | iteration of the loop. This is sometimes useful to poll and handle new |
|
|
921 | events while doing lengthy calculations, to keep the program responsive. |
709 | |
922 | |
710 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
923 | A flags value of C<EVRUN_ONCE> will look for new events (waiting if |
711 | necessary) and will handle those and any already outstanding ones. It |
924 | necessary) and will handle those and any already outstanding ones. It |
712 | will block your process until at least one new event arrives (which could |
925 | will block your process until at least one new event arrives (which could |
713 | be an event internal to libev itself, so there is no guarantee that a |
926 | be an event internal to libev itself, so there is no guarantee that a |
714 | user-registered callback will be called), and will return after one |
927 | user-registered callback will be called), and will return after one |
715 | iteration of the loop. |
928 | iteration of the loop. |
716 | |
929 | |
717 | This is useful if you are waiting for some external event in conjunction |
930 | This is useful if you are waiting for some external event in conjunction |
718 | with something not expressible using other libev watchers (i.e. "roll your |
931 | with something not expressible using other libev watchers (i.e. "roll your |
719 | own C<ev_loop>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is |
932 | own C<ev_run>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is |
720 | usually a better approach for this kind of thing. |
933 | usually a better approach for this kind of thing. |
721 | |
934 | |
722 | Here are the gory details of what C<ev_loop> does: |
935 | Here are the gory details of what C<ev_run> does (this is for your |
|
|
936 | understanding, not a guarantee that things will work exactly like this in |
|
|
937 | future versions): |
723 | |
938 | |
|
|
939 | - Increment loop depth. |
|
|
940 | - Reset the ev_break status. |
724 | - Before the first iteration, call any pending watchers. |
941 | - Before the first iteration, call any pending watchers. |
|
|
942 | LOOP: |
725 | * If EVFLAG_FORKCHECK was used, check for a fork. |
943 | - If EVFLAG_FORKCHECK was used, check for a fork. |
726 | - If a fork was detected (by any means), queue and call all fork watchers. |
944 | - If a fork was detected (by any means), queue and call all fork watchers. |
727 | - Queue and call all prepare watchers. |
945 | - Queue and call all prepare watchers. |
|
|
946 | - If ev_break was called, goto FINISH. |
728 | - If we have been forked, detach and recreate the kernel state |
947 | - If we have been forked, detach and recreate the kernel state |
729 | as to not disturb the other process. |
948 | as to not disturb the other process. |
730 | - Update the kernel state with all outstanding changes. |
949 | - Update the kernel state with all outstanding changes. |
731 | - Update the "event loop time" (ev_now ()). |
950 | - Update the "event loop time" (ev_now ()). |
732 | - Calculate for how long to sleep or block, if at all |
951 | - Calculate for how long to sleep or block, if at all |
733 | (active idle watchers, EVLOOP_NONBLOCK or not having |
952 | (active idle watchers, EVRUN_NOWAIT or not having |
734 | any active watchers at all will result in not sleeping). |
953 | any active watchers at all will result in not sleeping). |
735 | - Sleep if the I/O and timer collect interval say so. |
954 | - Sleep if the I/O and timer collect interval say so. |
|
|
955 | - Increment loop iteration counter. |
736 | - Block the process, waiting for any events. |
956 | - Block the process, waiting for any events. |
737 | - Queue all outstanding I/O (fd) events. |
957 | - Queue all outstanding I/O (fd) events. |
738 | - Update the "event loop time" (ev_now ()), and do time jump adjustments. |
958 | - Update the "event loop time" (ev_now ()), and do time jump adjustments. |
739 | - Queue all expired timers. |
959 | - Queue all expired timers. |
740 | - Queue all expired periodics. |
960 | - Queue all expired periodics. |
741 | - Unless any events are pending now, queue all idle watchers. |
961 | - Queue all idle watchers with priority higher than that of pending events. |
742 | - Queue all check watchers. |
962 | - Queue all check watchers. |
743 | - Call all queued watchers in reverse order (i.e. check watchers first). |
963 | - Call all queued watchers in reverse order (i.e. check watchers first). |
744 | Signals and child watchers are implemented as I/O watchers, and will |
964 | Signals and child watchers are implemented as I/O watchers, and will |
745 | be handled here by queueing them when their watcher gets executed. |
965 | be handled here by queueing them when their watcher gets executed. |
746 | - If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
966 | - If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT |
747 | were used, or there are no active watchers, return, otherwise |
967 | were used, or there are no active watchers, goto FINISH, otherwise |
748 | continue with step *. |
968 | continue with step LOOP. |
|
|
969 | FINISH: |
|
|
970 | - Reset the ev_break status iff it was EVBREAK_ONE. |
|
|
971 | - Decrement the loop depth. |
|
|
972 | - Return. |
749 | |
973 | |
750 | Example: Queue some jobs and then loop until no events are outstanding |
974 | Example: Queue some jobs and then loop until no events are outstanding |
751 | anymore. |
975 | anymore. |
752 | |
976 | |
753 | ... queue jobs here, make sure they register event watchers as long |
977 | ... queue jobs here, make sure they register event watchers as long |
754 | ... as they still have work to do (even an idle watcher will do..) |
978 | ... as they still have work to do (even an idle watcher will do..) |
755 | ev_loop (my_loop, 0); |
979 | ev_run (my_loop, 0); |
756 | ... jobs done or somebody called unloop. yeah! |
980 | ... jobs done or somebody called break. yeah! |
757 | |
981 | |
758 | =item ev_unloop (loop, how) |
982 | =item ev_break (loop, how) |
759 | |
983 | |
760 | Can be used to make a call to C<ev_loop> return early (but only after it |
984 | Can be used to make a call to C<ev_run> return early (but only after it |
761 | has processed all outstanding events). The C<how> argument must be either |
985 | has processed all outstanding events). The C<how> argument must be either |
762 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
986 | C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or |
763 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
987 | C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return. |
764 | |
988 | |
765 | This "unloop state" will be cleared when entering C<ev_loop> again. |
989 | This "break state" will be cleared on the next call to C<ev_run>. |
766 | |
990 | |
767 | It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls. |
991 | It is safe to call C<ev_break> from outside any C<ev_run> calls, too, in |
|
|
992 | which case it will have no effect. |
768 | |
993 | |
769 | =item ev_ref (loop) |
994 | =item ev_ref (loop) |
770 | |
995 | |
771 | =item ev_unref (loop) |
996 | =item ev_unref (loop) |
772 | |
997 | |
773 | Ref/unref can be used to add or remove a reference count on the event |
998 | Ref/unref can be used to add or remove a reference count on the event |
774 | loop: Every watcher keeps one reference, and as long as the reference |
999 | loop: Every watcher keeps one reference, and as long as the reference |
775 | count is nonzero, C<ev_loop> will not return on its own. |
1000 | count is nonzero, C<ev_run> will not return on its own. |
776 | |
1001 | |
777 | If you have a watcher you never unregister that should not keep C<ev_loop> |
1002 | This is useful when you have a watcher that you never intend to |
778 | from returning, call ev_unref() after starting, and ev_ref() before |
1003 | unregister, but that nevertheless should not keep C<ev_run> from |
|
|
1004 | returning. In such a case, call C<ev_unref> after starting, and C<ev_ref> |
779 | stopping it. |
1005 | before stopping it. |
780 | |
1006 | |
781 | As an example, libev itself uses this for its internal signal pipe: It |
1007 | As an example, libev itself uses this for its internal signal pipe: It |
782 | is not visible to the libev user and should not keep C<ev_loop> from |
1008 | is not visible to the libev user and should not keep C<ev_run> from |
783 | exiting if no event watchers registered by it are active. It is also an |
1009 | exiting if no event watchers registered by it are active. It is also an |
784 | excellent way to do this for generic recurring timers or from within |
1010 | excellent way to do this for generic recurring timers or from within |
785 | third-party libraries. Just remember to I<unref after start> and I<ref |
1011 | third-party libraries. Just remember to I<unref after start> and I<ref |
786 | before stop> (but only if the watcher wasn't active before, or was active |
1012 | before stop> (but only if the watcher wasn't active before, or was active |
787 | before, respectively. Note also that libev might stop watchers itself |
1013 | before, respectively. Note also that libev might stop watchers itself |
788 | (e.g. non-repeating timers) in which case you have to C<ev_ref> |
1014 | (e.g. non-repeating timers) in which case you have to C<ev_ref> |
789 | in the callback). |
1015 | in the callback). |
790 | |
1016 | |
791 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
1017 | Example: Create a signal watcher, but keep it from keeping C<ev_run> |
792 | running when nothing else is active. |
1018 | running when nothing else is active. |
793 | |
1019 | |
794 | ev_signal exitsig; |
1020 | ev_signal exitsig; |
795 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
1021 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
796 | ev_signal_start (loop, &exitsig); |
1022 | ev_signal_start (loop, &exitsig); |
797 | evf_unref (loop); |
1023 | ev_unref (loop); |
798 | |
1024 | |
799 | Example: For some weird reason, unregister the above signal handler again. |
1025 | Example: For some weird reason, unregister the above signal handler again. |
800 | |
1026 | |
801 | ev_ref (loop); |
1027 | ev_ref (loop); |
802 | ev_signal_stop (loop, &exitsig); |
1028 | ev_signal_stop (loop, &exitsig); |
… | |
… | |
822 | overhead for the actual polling but can deliver many events at once. |
1048 | overhead for the actual polling but can deliver many events at once. |
823 | |
1049 | |
824 | By setting a higher I<io collect interval> you allow libev to spend more |
1050 | By setting a higher I<io collect interval> you allow libev to spend more |
825 | time collecting I/O events, so you can handle more events per iteration, |
1051 | time collecting I/O events, so you can handle more events per iteration, |
826 | at the cost of increasing latency. Timeouts (both C<ev_periodic> and |
1052 | at the cost of increasing latency. Timeouts (both C<ev_periodic> and |
827 | C<ev_timer>) will be not affected. Setting this to a non-null value will |
1053 | C<ev_timer>) will not be affected. Setting this to a non-null value will |
828 | introduce an additional C<ev_sleep ()> call into most loop iterations. The |
1054 | introduce an additional C<ev_sleep ()> call into most loop iterations. The |
829 | sleep time ensures that libev will not poll for I/O events more often then |
1055 | sleep time ensures that libev will not poll for I/O events more often then |
830 | once per this interval, on average. |
1056 | once per this interval, on average (as long as the host time resolution is |
|
|
1057 | good enough). |
831 | |
1058 | |
832 | Likewise, by setting a higher I<timeout collect interval> you allow libev |
1059 | Likewise, by setting a higher I<timeout collect interval> you allow libev |
833 | to spend more time collecting timeouts, at the expense of increased |
1060 | to spend more time collecting timeouts, at the expense of increased |
834 | latency/jitter/inexactness (the watcher callback will be called |
1061 | latency/jitter/inexactness (the watcher callback will be called |
835 | later). C<ev_io> watchers will not be affected. Setting this to a non-null |
1062 | later). C<ev_io> watchers will not be affected. Setting this to a non-null |
… | |
… | |
841 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
1068 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
842 | as this approaches the timing granularity of most systems. Note that if |
1069 | as this approaches the timing granularity of most systems. Note that if |
843 | you do transactions with the outside world and you can't increase the |
1070 | you do transactions with the outside world and you can't increase the |
844 | parallelity, then this setting will limit your transaction rate (if you |
1071 | parallelity, then this setting will limit your transaction rate (if you |
845 | need to poll once per transaction and the I/O collect interval is 0.01, |
1072 | need to poll once per transaction and the I/O collect interval is 0.01, |
846 | then you can't do more than 100 transations per second). |
1073 | then you can't do more than 100 transactions per second). |
847 | |
1074 | |
848 | Setting the I<timeout collect interval> can improve the opportunity for |
1075 | Setting the I<timeout collect interval> can improve the opportunity for |
849 | saving power, as the program will "bundle" timer callback invocations that |
1076 | saving power, as the program will "bundle" timer callback invocations that |
850 | are "near" in time together, by delaying some, thus reducing the number of |
1077 | are "near" in time together, by delaying some, thus reducing the number of |
851 | times the process sleeps and wakes up again. Another useful technique to |
1078 | times the process sleeps and wakes up again. Another useful technique to |
… | |
… | |
859 | ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01); |
1086 | ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01); |
860 | |
1087 | |
861 | =item ev_invoke_pending (loop) |
1088 | =item ev_invoke_pending (loop) |
862 | |
1089 | |
863 | This call will simply invoke all pending watchers while resetting their |
1090 | This call will simply invoke all pending watchers while resetting their |
864 | pending state. Normally, C<ev_loop> does this automatically when required, |
1091 | pending state. Normally, C<ev_run> does this automatically when required, |
865 | but when overriding the invoke callback this call comes handy. |
1092 | but when overriding the invoke callback this call comes handy. This |
|
|
1093 | function can be invoked from a watcher - this can be useful for example |
|
|
1094 | when you want to do some lengthy calculation and want to pass further |
|
|
1095 | event handling to another thread (you still have to make sure only one |
|
|
1096 | thread executes within C<ev_invoke_pending> or C<ev_run> of course). |
|
|
1097 | |
|
|
1098 | =item int ev_pending_count (loop) |
|
|
1099 | |
|
|
1100 | Returns the number of pending watchers - zero indicates that no watchers |
|
|
1101 | are pending. |
866 | |
1102 | |
867 | =item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P)) |
1103 | =item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P)) |
868 | |
1104 | |
869 | This overrides the invoke pending functionality of the loop: Instead of |
1105 | This overrides the invoke pending functionality of the loop: Instead of |
870 | invoking all pending watchers when there are any, C<ev_loop> will call |
1106 | invoking all pending watchers when there are any, C<ev_run> will call |
871 | this callback instead. This is useful, for example, when you want to |
1107 | this callback instead. This is useful, for example, when you want to |
872 | invoke the actual watchers inside another context (another thread etc.). |
1108 | invoke the actual watchers inside another context (another thread etc.). |
873 | |
1109 | |
874 | If you want to reset the callback, use C<ev_invoke_pending> as new |
1110 | If you want to reset the callback, use C<ev_invoke_pending> as new |
875 | callback. |
1111 | callback. |
876 | |
1112 | |
877 | =item ev_set_loop_release_cb (loop, void (*release)(EV_P), void (*acquire)(EV_P)) |
1113 | =item ev_set_loop_release_cb (loop, void (*release)(EV_P) throw (), void (*acquire)(EV_P) throw ()) |
878 | |
1114 | |
879 | Sometimes you want to share the same loop between multiple threads. This |
1115 | Sometimes you want to share the same loop between multiple threads. This |
880 | can be done relatively simply by putting mutex_lock/unlock calls around |
1116 | can be done relatively simply by putting mutex_lock/unlock calls around |
881 | each call to a libev function. |
1117 | each call to a libev function. |
882 | |
1118 | |
883 | However, C<ev_loop> can run an indefinite time, so it is not feasible to |
1119 | However, C<ev_run> can run an indefinite time, so it is not feasible |
884 | wait for it to return. One way around this is to wake up the loop via |
1120 | to wait for it to return. One way around this is to wake up the event |
885 | C<ev_unloop> and C<av_async_send>, another way is to set these I<release> |
1121 | loop via C<ev_break> and C<ev_async_send>, another way is to set these |
886 | and I<acquire> callbacks on the loop. |
1122 | I<release> and I<acquire> callbacks on the loop. |
887 | |
1123 | |
888 | When set, then C<release> will be called just before the thread is |
1124 | When set, then C<release> will be called just before the thread is |
889 | suspended waiting for new events, and C<acquire> is called just |
1125 | suspended waiting for new events, and C<acquire> is called just |
890 | afterwards. |
1126 | afterwards. |
891 | |
1127 | |
… | |
… | |
894 | |
1130 | |
895 | While event loop modifications are allowed between invocations of |
1131 | While event loop modifications are allowed between invocations of |
896 | C<release> and C<acquire> (that's their only purpose after all), no |
1132 | C<release> and C<acquire> (that's their only purpose after all), no |
897 | modifications done will affect the event loop, i.e. adding watchers will |
1133 | modifications done will affect the event loop, i.e. adding watchers will |
898 | have no effect on the set of file descriptors being watched, or the time |
1134 | have no effect on the set of file descriptors being watched, or the time |
899 | waited. USe an C<ev_async> watcher to wake up C<ev_loop> when you want it |
1135 | waited. Use an C<ev_async> watcher to wake up C<ev_run> when you want it |
900 | to take note of any changes you made. |
1136 | to take note of any changes you made. |
901 | |
1137 | |
902 | In theory, threads executing C<ev_loop> will be async-cancel safe between |
1138 | In theory, threads executing C<ev_run> will be async-cancel safe between |
903 | invocations of C<release> and C<acquire>. |
1139 | invocations of C<release> and C<acquire>. |
904 | |
1140 | |
905 | See also the locking example in the C<THREADS> section later in this |
1141 | See also the locking example in the C<THREADS> section later in this |
906 | document. |
1142 | document. |
907 | |
1143 | |
908 | =item ev_set_userdata (loop, void *data) |
1144 | =item ev_set_userdata (loop, void *data) |
909 | |
1145 | |
910 | =item ev_userdata (loop) |
1146 | =item void *ev_userdata (loop) |
911 | |
1147 | |
912 | Set and retrieve a single C<void *> associated with a loop. When |
1148 | Set and retrieve a single C<void *> associated with a loop. When |
913 | C<ev_set_userdata> has never been called, then C<ev_userdata> returns |
1149 | C<ev_set_userdata> has never been called, then C<ev_userdata> returns |
914 | C<0.> |
1150 | C<0>. |
915 | |
1151 | |
916 | These two functions can be used to associate arbitrary data with a loop, |
1152 | These two functions can be used to associate arbitrary data with a loop, |
917 | and are intended solely for the C<invoke_pending_cb>, C<release> and |
1153 | and are intended solely for the C<invoke_pending_cb>, C<release> and |
918 | C<acquire> callbacks described above, but of course can be (ab-)used for |
1154 | C<acquire> callbacks described above, but of course can be (ab-)used for |
919 | any other purpose as well. |
1155 | any other purpose as well. |
920 | |
1156 | |
921 | =item ev_loop_verify (loop) |
1157 | =item ev_verify (loop) |
922 | |
1158 | |
923 | This function only does something when C<EV_VERIFY> support has been |
1159 | This function only does something when C<EV_VERIFY> support has been |
924 | compiled in, which is the default for non-minimal builds. It tries to go |
1160 | compiled in, which is the default for non-minimal builds. It tries to go |
925 | through all internal structures and checks them for validity. If anything |
1161 | through all internal structures and checks them for validity. If anything |
926 | is found to be inconsistent, it will print an error message to standard |
1162 | is found to be inconsistent, it will print an error message to standard |
… | |
… | |
937 | |
1173 | |
938 | In the following description, uppercase C<TYPE> in names stands for the |
1174 | In the following description, uppercase C<TYPE> in names stands for the |
939 | watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer |
1175 | watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer |
940 | watchers and C<ev_io_start> for I/O watchers. |
1176 | watchers and C<ev_io_start> for I/O watchers. |
941 | |
1177 | |
942 | A watcher is a structure that you create and register to record your |
1178 | A watcher is an opaque structure that you allocate and register to record |
943 | interest in some event. For instance, if you want to wait for STDIN to |
1179 | your interest in some event. To make a concrete example, imagine you want |
944 | become readable, you would create an C<ev_io> watcher for that: |
1180 | to wait for STDIN to become readable, you would create an C<ev_io> watcher |
|
|
1181 | for that: |
945 | |
1182 | |
946 | static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
1183 | static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
947 | { |
1184 | { |
948 | ev_io_stop (w); |
1185 | ev_io_stop (w); |
949 | ev_unloop (loop, EVUNLOOP_ALL); |
1186 | ev_break (loop, EVBREAK_ALL); |
950 | } |
1187 | } |
951 | |
1188 | |
952 | struct ev_loop *loop = ev_default_loop (0); |
1189 | struct ev_loop *loop = ev_default_loop (0); |
953 | |
1190 | |
954 | ev_io stdin_watcher; |
1191 | ev_io stdin_watcher; |
955 | |
1192 | |
956 | ev_init (&stdin_watcher, my_cb); |
1193 | ev_init (&stdin_watcher, my_cb); |
957 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
1194 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
958 | ev_io_start (loop, &stdin_watcher); |
1195 | ev_io_start (loop, &stdin_watcher); |
959 | |
1196 | |
960 | ev_loop (loop, 0); |
1197 | ev_run (loop, 0); |
961 | |
1198 | |
962 | As you can see, you are responsible for allocating the memory for your |
1199 | As you can see, you are responsible for allocating the memory for your |
963 | watcher structures (and it is I<usually> a bad idea to do this on the |
1200 | watcher structures (and it is I<usually> a bad idea to do this on the |
964 | stack). |
1201 | stack). |
965 | |
1202 | |
966 | Each watcher has an associated watcher structure (called C<struct ev_TYPE> |
1203 | Each watcher has an associated watcher structure (called C<struct ev_TYPE> |
967 | or simply C<ev_TYPE>, as typedefs are provided for all watcher structs). |
1204 | or simply C<ev_TYPE>, as typedefs are provided for all watcher structs). |
968 | |
1205 | |
969 | Each watcher structure must be initialised by a call to C<ev_init |
1206 | Each watcher structure must be initialised by a call to C<ev_init (watcher |
970 | (watcher *, callback)>, which expects a callback to be provided. This |
1207 | *, callback)>, which expects a callback to be provided. This callback is |
971 | callback gets invoked each time the event occurs (or, in the case of I/O |
1208 | invoked each time the event occurs (or, in the case of I/O watchers, each |
972 | watchers, each time the event loop detects that the file descriptor given |
1209 | time the event loop detects that the file descriptor given is readable |
973 | is readable and/or writable). |
1210 | and/or writable). |
974 | |
1211 | |
975 | Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >> |
1212 | Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >> |
976 | macro to configure it, with arguments specific to the watcher type. There |
1213 | macro to configure it, with arguments specific to the watcher type. There |
977 | is also a macro to combine initialisation and setting in one call: C<< |
1214 | is also a macro to combine initialisation and setting in one call: C<< |
978 | ev_TYPE_init (watcher *, callback, ...) >>. |
1215 | ev_TYPE_init (watcher *, callback, ...) >>. |
… | |
… | |
981 | with a watcher-specific start function (C<< ev_TYPE_start (loop, watcher |
1218 | with a watcher-specific start function (C<< ev_TYPE_start (loop, watcher |
982 | *) >>), and you can stop watching for events at any time by calling the |
1219 | *) >>), and you can stop watching for events at any time by calling the |
983 | corresponding stop function (C<< ev_TYPE_stop (loop, watcher *) >>. |
1220 | corresponding stop function (C<< ev_TYPE_stop (loop, watcher *) >>. |
984 | |
1221 | |
985 | As long as your watcher is active (has been started but not stopped) you |
1222 | As long as your watcher is active (has been started but not stopped) you |
986 | must not touch the values stored in it. Most specifically you must never |
1223 | must not touch the values stored in it except when explicitly documented |
987 | reinitialise it or call its C<ev_TYPE_set> macro. |
1224 | otherwise. Most specifically you must never reinitialise it or call its |
|
|
1225 | C<ev_TYPE_set> macro. |
988 | |
1226 | |
989 | Each and every callback receives the event loop pointer as first, the |
1227 | Each and every callback receives the event loop pointer as first, the |
990 | registered watcher structure as second, and a bitset of received events as |
1228 | registered watcher structure as second, and a bitset of received events as |
991 | third argument. |
1229 | third argument. |
992 | |
1230 | |
… | |
… | |
1001 | =item C<EV_WRITE> |
1239 | =item C<EV_WRITE> |
1002 | |
1240 | |
1003 | The file descriptor in the C<ev_io> watcher has become readable and/or |
1241 | The file descriptor in the C<ev_io> watcher has become readable and/or |
1004 | writable. |
1242 | writable. |
1005 | |
1243 | |
1006 | =item C<EV_TIMEOUT> |
1244 | =item C<EV_TIMER> |
1007 | |
1245 | |
1008 | The C<ev_timer> watcher has timed out. |
1246 | The C<ev_timer> watcher has timed out. |
1009 | |
1247 | |
1010 | =item C<EV_PERIODIC> |
1248 | =item C<EV_PERIODIC> |
1011 | |
1249 | |
… | |
… | |
1029 | |
1267 | |
1030 | =item C<EV_PREPARE> |
1268 | =item C<EV_PREPARE> |
1031 | |
1269 | |
1032 | =item C<EV_CHECK> |
1270 | =item C<EV_CHECK> |
1033 | |
1271 | |
1034 | All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts |
1272 | All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts to |
1035 | to gather new events, and all C<ev_check> watchers are invoked just after |
1273 | gather new events, and all C<ev_check> watchers are queued (not invoked) |
1036 | C<ev_loop> has gathered them, but before it invokes any callbacks for any |
1274 | just after C<ev_run> has gathered them, but before it queues any callbacks |
|
|
1275 | for any received events. That means C<ev_prepare> watchers are the last |
|
|
1276 | watchers invoked before the event loop sleeps or polls for new events, and |
|
|
1277 | C<ev_check> watchers will be invoked before any other watchers of the same |
|
|
1278 | or lower priority within an event loop iteration. |
|
|
1279 | |
1037 | received events. Callbacks of both watcher types can start and stop as |
1280 | Callbacks of both watcher types can start and stop as many watchers as |
1038 | many watchers as they want, and all of them will be taken into account |
1281 | they want, and all of them will be taken into account (for example, a |
1039 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
1282 | C<ev_prepare> watcher might start an idle watcher to keep C<ev_run> from |
1040 | C<ev_loop> from blocking). |
1283 | blocking). |
1041 | |
1284 | |
1042 | =item C<EV_EMBED> |
1285 | =item C<EV_EMBED> |
1043 | |
1286 | |
1044 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
1287 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
1045 | |
1288 | |
1046 | =item C<EV_FORK> |
1289 | =item C<EV_FORK> |
1047 | |
1290 | |
1048 | The event loop has been resumed in the child process after fork (see |
1291 | The event loop has been resumed in the child process after fork (see |
1049 | C<ev_fork>). |
1292 | C<ev_fork>). |
|
|
1293 | |
|
|
1294 | =item C<EV_CLEANUP> |
|
|
1295 | |
|
|
1296 | The event loop is about to be destroyed (see C<ev_cleanup>). |
1050 | |
1297 | |
1051 | =item C<EV_ASYNC> |
1298 | =item C<EV_ASYNC> |
1052 | |
1299 | |
1053 | The given async watcher has been asynchronously notified (see C<ev_async>). |
1300 | The given async watcher has been asynchronously notified (see C<ev_async>). |
1054 | |
1301 | |
… | |
… | |
1101 | |
1348 | |
1102 | ev_io w; |
1349 | ev_io w; |
1103 | ev_init (&w, my_cb); |
1350 | ev_init (&w, my_cb); |
1104 | ev_io_set (&w, STDIN_FILENO, EV_READ); |
1351 | ev_io_set (&w, STDIN_FILENO, EV_READ); |
1105 | |
1352 | |
1106 | =item C<ev_TYPE_set> (ev_TYPE *, [args]) |
1353 | =item C<ev_TYPE_set> (ev_TYPE *watcher, [args]) |
1107 | |
1354 | |
1108 | This macro initialises the type-specific parts of a watcher. You need to |
1355 | This macro initialises the type-specific parts of a watcher. You need to |
1109 | call C<ev_init> at least once before you call this macro, but you can |
1356 | call C<ev_init> at least once before you call this macro, but you can |
1110 | call C<ev_TYPE_set> any number of times. You must not, however, call this |
1357 | call C<ev_TYPE_set> any number of times. You must not, however, call this |
1111 | macro on a watcher that is active (it can be pending, however, which is a |
1358 | macro on a watcher that is active (it can be pending, however, which is a |
… | |
… | |
1124 | |
1371 | |
1125 | Example: Initialise and set an C<ev_io> watcher in one step. |
1372 | Example: Initialise and set an C<ev_io> watcher in one step. |
1126 | |
1373 | |
1127 | ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
1374 | ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
1128 | |
1375 | |
1129 | =item C<ev_TYPE_start> (loop *, ev_TYPE *watcher) |
1376 | =item C<ev_TYPE_start> (loop, ev_TYPE *watcher) |
1130 | |
1377 | |
1131 | Starts (activates) the given watcher. Only active watchers will receive |
1378 | Starts (activates) the given watcher. Only active watchers will receive |
1132 | events. If the watcher is already active nothing will happen. |
1379 | events. If the watcher is already active nothing will happen. |
1133 | |
1380 | |
1134 | Example: Start the C<ev_io> watcher that is being abused as example in this |
1381 | Example: Start the C<ev_io> watcher that is being abused as example in this |
1135 | whole section. |
1382 | whole section. |
1136 | |
1383 | |
1137 | ev_io_start (EV_DEFAULT_UC, &w); |
1384 | ev_io_start (EV_DEFAULT_UC, &w); |
1138 | |
1385 | |
1139 | =item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher) |
1386 | =item C<ev_TYPE_stop> (loop, ev_TYPE *watcher) |
1140 | |
1387 | |
1141 | Stops the given watcher if active, and clears the pending status (whether |
1388 | Stops the given watcher if active, and clears the pending status (whether |
1142 | the watcher was active or not). |
1389 | the watcher was active or not). |
1143 | |
1390 | |
1144 | It is possible that stopped watchers are pending - for example, |
1391 | It is possible that stopped watchers are pending - for example, |
… | |
… | |
1164 | |
1411 | |
1165 | =item callback ev_cb (ev_TYPE *watcher) |
1412 | =item callback ev_cb (ev_TYPE *watcher) |
1166 | |
1413 | |
1167 | Returns the callback currently set on the watcher. |
1414 | Returns the callback currently set on the watcher. |
1168 | |
1415 | |
1169 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1416 | =item ev_set_cb (ev_TYPE *watcher, callback) |
1170 | |
1417 | |
1171 | Change the callback. You can change the callback at virtually any time |
1418 | Change the callback. You can change the callback at virtually any time |
1172 | (modulo threads). |
1419 | (modulo threads). |
1173 | |
1420 | |
1174 | =item ev_set_priority (ev_TYPE *watcher, priority) |
1421 | =item ev_set_priority (ev_TYPE *watcher, int priority) |
1175 | |
1422 | |
1176 | =item int ev_priority (ev_TYPE *watcher) |
1423 | =item int ev_priority (ev_TYPE *watcher) |
1177 | |
1424 | |
1178 | Set and query the priority of the watcher. The priority is a small |
1425 | Set and query the priority of the watcher. The priority is a small |
1179 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
1426 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
… | |
… | |
1192 | or might not have been clamped to the valid range. |
1439 | or might not have been clamped to the valid range. |
1193 | |
1440 | |
1194 | The default priority used by watchers when no priority has been set is |
1441 | The default priority used by watchers when no priority has been set is |
1195 | always C<0>, which is supposed to not be too high and not be too low :). |
1442 | always C<0>, which is supposed to not be too high and not be too low :). |
1196 | |
1443 | |
1197 | See L<WATCHER PRIORITY MODELS>, below, for a more thorough treatment of |
1444 | See L</WATCHER PRIORITY MODELS>, below, for a more thorough treatment of |
1198 | priorities. |
1445 | priorities. |
1199 | |
1446 | |
1200 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
1447 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
1201 | |
1448 | |
1202 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
1449 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
… | |
… | |
1211 | watcher isn't pending it does nothing and returns C<0>. |
1458 | watcher isn't pending it does nothing and returns C<0>. |
1212 | |
1459 | |
1213 | Sometimes it can be useful to "poll" a watcher instead of waiting for its |
1460 | Sometimes it can be useful to "poll" a watcher instead of waiting for its |
1214 | callback to be invoked, which can be accomplished with this function. |
1461 | callback to be invoked, which can be accomplished with this function. |
1215 | |
1462 | |
|
|
1463 | =item ev_feed_event (loop, ev_TYPE *watcher, int revents) |
|
|
1464 | |
|
|
1465 | Feeds the given event set into the event loop, as if the specified event |
|
|
1466 | had happened for the specified watcher (which must be a pointer to an |
|
|
1467 | initialised but not necessarily started event watcher). Obviously you must |
|
|
1468 | not free the watcher as long as it has pending events. |
|
|
1469 | |
|
|
1470 | Stopping the watcher, letting libev invoke it, or calling |
|
|
1471 | C<ev_clear_pending> will clear the pending event, even if the watcher was |
|
|
1472 | not started in the first place. |
|
|
1473 | |
|
|
1474 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
|
|
1475 | functions that do not need a watcher. |
|
|
1476 | |
1216 | =back |
1477 | =back |
1217 | |
1478 | |
|
|
1479 | See also the L</ASSOCIATING CUSTOM DATA WITH A WATCHER> and L</BUILDING YOUR |
|
|
1480 | OWN COMPOSITE WATCHERS> idioms. |
1218 | |
1481 | |
1219 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
1482 | =head2 WATCHER STATES |
1220 | |
1483 | |
1221 | Each watcher has, by default, a member C<void *data> that you can change |
1484 | There are various watcher states mentioned throughout this manual - |
1222 | and read at any time: libev will completely ignore it. This can be used |
1485 | active, pending and so on. In this section these states and the rules to |
1223 | to associate arbitrary data with your watcher. If you need more data and |
1486 | transition between them will be described in more detail - and while these |
1224 | don't want to allocate memory and store a pointer to it in that data |
1487 | rules might look complicated, they usually do "the right thing". |
1225 | member, you can also "subclass" the watcher type and provide your own |
|
|
1226 | data: |
|
|
1227 | |
1488 | |
1228 | struct my_io |
1489 | =over 4 |
1229 | { |
|
|
1230 | ev_io io; |
|
|
1231 | int otherfd; |
|
|
1232 | void *somedata; |
|
|
1233 | struct whatever *mostinteresting; |
|
|
1234 | }; |
|
|
1235 | |
1490 | |
1236 | ... |
1491 | =item initialised |
1237 | struct my_io w; |
|
|
1238 | ev_io_init (&w.io, my_cb, fd, EV_READ); |
|
|
1239 | |
1492 | |
1240 | And since your callback will be called with a pointer to the watcher, you |
1493 | Before a watcher can be registered with the event loop it has to be |
1241 | can cast it back to your own type: |
1494 | initialised. This can be done with a call to C<ev_TYPE_init>, or calls to |
|
|
1495 | C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function. |
1242 | |
1496 | |
1243 | static void my_cb (struct ev_loop *loop, ev_io *w_, int revents) |
1497 | In this state it is simply some block of memory that is suitable for |
1244 | { |
1498 | use in an event loop. It can be moved around, freed, reused etc. at |
1245 | struct my_io *w = (struct my_io *)w_; |
1499 | will - as long as you either keep the memory contents intact, or call |
1246 | ... |
1500 | C<ev_TYPE_init> again. |
1247 | } |
|
|
1248 | |
1501 | |
1249 | More interesting and less C-conformant ways of casting your callback type |
1502 | =item started/running/active |
1250 | instead have been omitted. |
|
|
1251 | |
1503 | |
1252 | Another common scenario is to use some data structure with multiple |
1504 | Once a watcher has been started with a call to C<ev_TYPE_start> it becomes |
1253 | embedded watchers: |
1505 | property of the event loop, and is actively waiting for events. While in |
|
|
1506 | this state it cannot be accessed (except in a few documented ways), moved, |
|
|
1507 | freed or anything else - the only legal thing is to keep a pointer to it, |
|
|
1508 | and call libev functions on it that are documented to work on active watchers. |
1254 | |
1509 | |
1255 | struct my_biggy |
1510 | =item pending |
1256 | { |
|
|
1257 | int some_data; |
|
|
1258 | ev_timer t1; |
|
|
1259 | ev_timer t2; |
|
|
1260 | } |
|
|
1261 | |
1511 | |
1262 | In this case getting the pointer to C<my_biggy> is a bit more |
1512 | If a watcher is active and libev determines that an event it is interested |
1263 | complicated: Either you store the address of your C<my_biggy> struct |
1513 | in has occurred (such as a timer expiring), it will become pending. It will |
1264 | in the C<data> member of the watcher (for woozies), or you need to use |
1514 | stay in this pending state until either it is stopped or its callback is |
1265 | some pointer arithmetic using C<offsetof> inside your watchers (for real |
1515 | about to be invoked, so it is not normally pending inside the watcher |
1266 | programmers): |
1516 | callback. |
1267 | |
1517 | |
1268 | #include <stddef.h> |
1518 | The watcher might or might not be active while it is pending (for example, |
|
|
1519 | an expired non-repeating timer can be pending but no longer active). If it |
|
|
1520 | is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>), |
|
|
1521 | but it is still property of the event loop at this time, so cannot be |
|
|
1522 | moved, freed or reused. And if it is active the rules described in the |
|
|
1523 | previous item still apply. |
1269 | |
1524 | |
1270 | static void |
1525 | It is also possible to feed an event on a watcher that is not active (e.g. |
1271 | t1_cb (EV_P_ ev_timer *w, int revents) |
1526 | via C<ev_feed_event>), in which case it becomes pending without being |
1272 | { |
1527 | active. |
1273 | struct my_biggy big = (struct my_biggy *) |
|
|
1274 | (((char *)w) - offsetof (struct my_biggy, t1)); |
|
|
1275 | } |
|
|
1276 | |
1528 | |
1277 | static void |
1529 | =item stopped |
1278 | t2_cb (EV_P_ ev_timer *w, int revents) |
1530 | |
1279 | { |
1531 | A watcher can be stopped implicitly by libev (in which case it might still |
1280 | struct my_biggy big = (struct my_biggy *) |
1532 | be pending), or explicitly by calling its C<ev_TYPE_stop> function. The |
1281 | (((char *)w) - offsetof (struct my_biggy, t2)); |
1533 | latter will clear any pending state the watcher might be in, regardless |
1282 | } |
1534 | of whether it was active or not, so stopping a watcher explicitly before |
|
|
1535 | freeing it is often a good idea. |
|
|
1536 | |
|
|
1537 | While stopped (and not pending) the watcher is essentially in the |
|
|
1538 | initialised state, that is, it can be reused, moved, modified in any way |
|
|
1539 | you wish (but when you trash the memory block, you need to C<ev_TYPE_init> |
|
|
1540 | it again). |
|
|
1541 | |
|
|
1542 | =back |
1283 | |
1543 | |
1284 | =head2 WATCHER PRIORITY MODELS |
1544 | =head2 WATCHER PRIORITY MODELS |
1285 | |
1545 | |
1286 | Many event loops support I<watcher priorities>, which are usually small |
1546 | Many event loops support I<watcher priorities>, which are usually small |
1287 | integers that influence the ordering of event callback invocation |
1547 | integers that influence the ordering of event callback invocation |
1288 | between watchers in some way, all else being equal. |
1548 | between watchers in some way, all else being equal. |
1289 | |
1549 | |
1290 | In libev, Watcher priorities can be set using C<ev_set_priority>. See its |
1550 | In libev, watcher priorities can be set using C<ev_set_priority>. See its |
1291 | description for the more technical details such as the actual priority |
1551 | description for the more technical details such as the actual priority |
1292 | range. |
1552 | range. |
1293 | |
1553 | |
1294 | There are two common ways how these these priorities are being interpreted |
1554 | There are two common ways how these these priorities are being interpreted |
1295 | by event loops: |
1555 | by event loops: |
… | |
… | |
1330 | |
1590 | |
1331 | For example, to emulate how many other event libraries handle priorities, |
1591 | For example, to emulate how many other event libraries handle priorities, |
1332 | you can associate an C<ev_idle> watcher to each such watcher, and in |
1592 | you can associate an C<ev_idle> watcher to each such watcher, and in |
1333 | the normal watcher callback, you just start the idle watcher. The real |
1593 | the normal watcher callback, you just start the idle watcher. The real |
1334 | processing is done in the idle watcher callback. This causes libev to |
1594 | processing is done in the idle watcher callback. This causes libev to |
1335 | continously poll and process kernel event data for the watcher, but when |
1595 | continuously poll and process kernel event data for the watcher, but when |
1336 | the lock-out case is known to be rare (which in turn is rare :), this is |
1596 | the lock-out case is known to be rare (which in turn is rare :), this is |
1337 | workable. |
1597 | workable. |
1338 | |
1598 | |
1339 | Usually, however, the lock-out model implemented that way will perform |
1599 | Usually, however, the lock-out model implemented that way will perform |
1340 | miserably under the type of load it was designed to handle. In that case, |
1600 | miserably under the type of load it was designed to handle. In that case, |
… | |
… | |
1354 | { |
1614 | { |
1355 | // stop the I/O watcher, we received the event, but |
1615 | // stop the I/O watcher, we received the event, but |
1356 | // are not yet ready to handle it. |
1616 | // are not yet ready to handle it. |
1357 | ev_io_stop (EV_A_ w); |
1617 | ev_io_stop (EV_A_ w); |
1358 | |
1618 | |
1359 | // start the idle watcher to ahndle the actual event. |
1619 | // start the idle watcher to handle the actual event. |
1360 | // it will not be executed as long as other watchers |
1620 | // it will not be executed as long as other watchers |
1361 | // with the default priority are receiving events. |
1621 | // with the default priority are receiving events. |
1362 | ev_idle_start (EV_A_ &idle); |
1622 | ev_idle_start (EV_A_ &idle); |
1363 | } |
1623 | } |
1364 | |
1624 | |
… | |
… | |
1389 | |
1649 | |
1390 | This section describes each watcher in detail, but will not repeat |
1650 | This section describes each watcher in detail, but will not repeat |
1391 | information given in the last section. Any initialisation/set macros, |
1651 | information given in the last section. Any initialisation/set macros, |
1392 | functions and members specific to the watcher type are explained. |
1652 | functions and members specific to the watcher type are explained. |
1393 | |
1653 | |
1394 | Members are additionally marked with either I<[read-only]>, meaning that, |
1654 | Most members are additionally marked with either I<[read-only]>, meaning |
1395 | while the watcher is active, you can look at the member and expect some |
1655 | that, while the watcher is active, you can look at the member and expect |
1396 | sensible content, but you must not modify it (you can modify it while the |
1656 | some sensible content, but you must not modify it (you can modify it while |
1397 | watcher is stopped to your hearts content), or I<[read-write]>, which |
1657 | the watcher is stopped to your hearts content), or I<[read-write]>, which |
1398 | means you can expect it to have some sensible content while the watcher |
1658 | means you can expect it to have some sensible content while the watcher |
1399 | is active, but you can also modify it. Modifying it may not do something |
1659 | is active, but you can also modify it. Modifying it may not do something |
1400 | sensible or take immediate effect (or do anything at all), but libev will |
1660 | sensible or take immediate effect (or do anything at all), but libev will |
1401 | not crash or malfunction in any way. |
1661 | not crash or malfunction in any way. |
1402 | |
1662 | |
|
|
1663 | In any case, the documentation for each member will explain what the |
|
|
1664 | effects are, and if there are any additional access restrictions. |
1403 | |
1665 | |
1404 | =head2 C<ev_io> - is this file descriptor readable or writable? |
1666 | =head2 C<ev_io> - is this file descriptor readable or writable? |
1405 | |
1667 | |
1406 | I/O watchers check whether a file descriptor is readable or writable |
1668 | I/O watchers check whether a file descriptor is readable or writable |
1407 | in each iteration of the event loop, or, more precisely, when reading |
1669 | in each iteration of the event loop, or, more precisely, when reading |
… | |
… | |
1414 | In general you can register as many read and/or write event watchers per |
1676 | In general you can register as many read and/or write event watchers per |
1415 | fd as you want (as long as you don't confuse yourself). Setting all file |
1677 | fd as you want (as long as you don't confuse yourself). Setting all file |
1416 | descriptors to non-blocking mode is also usually a good idea (but not |
1678 | descriptors to non-blocking mode is also usually a good idea (but not |
1417 | required if you know what you are doing). |
1679 | required if you know what you are doing). |
1418 | |
1680 | |
1419 | If you cannot use non-blocking mode, then force the use of a |
|
|
1420 | known-to-be-good backend (at the time of this writing, this includes only |
|
|
1421 | C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file |
|
|
1422 | descriptors for which non-blocking operation makes no sense (such as |
|
|
1423 | files) - libev doesn't guarentee any specific behaviour in that case. |
|
|
1424 | |
|
|
1425 | Another thing you have to watch out for is that it is quite easy to |
1681 | Another thing you have to watch out for is that it is quite easy to |
1426 | receive "spurious" readiness notifications, that is your callback might |
1682 | receive "spurious" readiness notifications, that is, your callback might |
1427 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1683 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1428 | because there is no data. Not only are some backends known to create a |
1684 | because there is no data. It is very easy to get into this situation even |
1429 | lot of those (for example Solaris ports), it is very easy to get into |
1685 | with a relatively standard program structure. Thus it is best to always |
1430 | this situation even with a relatively standard program structure. Thus |
1686 | use non-blocking I/O: An extra C<read>(2) returning C<EAGAIN> is far |
1431 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
|
|
1432 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
1687 | preferable to a program hanging until some data arrives. |
1433 | |
1688 | |
1434 | If you cannot run the fd in non-blocking mode (for example you should |
1689 | If you cannot run the fd in non-blocking mode (for example you should |
1435 | not play around with an Xlib connection), then you have to separately |
1690 | not play around with an Xlib connection), then you have to separately |
1436 | re-test whether a file descriptor is really ready with a known-to-be good |
1691 | re-test whether a file descriptor is really ready with a known-to-be good |
1437 | interface such as poll (fortunately in our Xlib example, Xlib already |
1692 | interface such as poll (fortunately in the case of Xlib, it already does |
1438 | does this on its own, so its quite safe to use). Some people additionally |
1693 | this on its own, so its quite safe to use). Some people additionally |
1439 | use C<SIGALRM> and an interval timer, just to be sure you won't block |
1694 | use C<SIGALRM> and an interval timer, just to be sure you won't block |
1440 | indefinitely. |
1695 | indefinitely. |
1441 | |
1696 | |
1442 | But really, best use non-blocking mode. |
1697 | But really, best use non-blocking mode. |
1443 | |
1698 | |
1444 | =head3 The special problem of disappearing file descriptors |
1699 | =head3 The special problem of disappearing file descriptors |
1445 | |
1700 | |
1446 | Some backends (e.g. kqueue, epoll) need to be told about closing a file |
1701 | Some backends (e.g. kqueue, epoll, linuxaio) need to be told about closing |
1447 | descriptor (either due to calling C<close> explicitly or any other means, |
1702 | a file descriptor (either due to calling C<close> explicitly or any other |
1448 | such as C<dup2>). The reason is that you register interest in some file |
1703 | means, such as C<dup2>). The reason is that you register interest in some |
1449 | descriptor, but when it goes away, the operating system will silently drop |
1704 | file descriptor, but when it goes away, the operating system will silently |
1450 | this interest. If another file descriptor with the same number then is |
1705 | drop this interest. If another file descriptor with the same number then |
1451 | registered with libev, there is no efficient way to see that this is, in |
1706 | is registered with libev, there is no efficient way to see that this is, |
1452 | fact, a different file descriptor. |
1707 | in fact, a different file descriptor. |
1453 | |
1708 | |
1454 | To avoid having to explicitly tell libev about such cases, libev follows |
1709 | To avoid having to explicitly tell libev about such cases, libev follows |
1455 | the following policy: Each time C<ev_io_set> is being called, libev |
1710 | the following policy: Each time C<ev_io_set> is being called, libev |
1456 | will assume that this is potentially a new file descriptor, otherwise |
1711 | will assume that this is potentially a new file descriptor, otherwise |
1457 | it is assumed that the file descriptor stays the same. That means that |
1712 | it is assumed that the file descriptor stays the same. That means that |
… | |
… | |
1471 | |
1726 | |
1472 | There is no workaround possible except not registering events |
1727 | There is no workaround possible except not registering events |
1473 | for potentially C<dup ()>'ed file descriptors, or to resort to |
1728 | for potentially C<dup ()>'ed file descriptors, or to resort to |
1474 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
1729 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
1475 | |
1730 | |
|
|
1731 | =head3 The special problem of files |
|
|
1732 | |
|
|
1733 | Many people try to use C<select> (or libev) on file descriptors |
|
|
1734 | representing files, and expect it to become ready when their program |
|
|
1735 | doesn't block on disk accesses (which can take a long time on their own). |
|
|
1736 | |
|
|
1737 | However, this cannot ever work in the "expected" way - you get a readiness |
|
|
1738 | notification as soon as the kernel knows whether and how much data is |
|
|
1739 | there, and in the case of open files, that's always the case, so you |
|
|
1740 | always get a readiness notification instantly, and your read (or possibly |
|
|
1741 | write) will still block on the disk I/O. |
|
|
1742 | |
|
|
1743 | Another way to view it is that in the case of sockets, pipes, character |
|
|
1744 | devices and so on, there is another party (the sender) that delivers data |
|
|
1745 | on its own, but in the case of files, there is no such thing: the disk |
|
|
1746 | will not send data on its own, simply because it doesn't know what you |
|
|
1747 | wish to read - you would first have to request some data. |
|
|
1748 | |
|
|
1749 | Since files are typically not-so-well supported by advanced notification |
|
|
1750 | mechanism, libev tries hard to emulate POSIX behaviour with respect |
|
|
1751 | to files, even though you should not use it. The reason for this is |
|
|
1752 | convenience: sometimes you want to watch STDIN or STDOUT, which is |
|
|
1753 | usually a tty, often a pipe, but also sometimes files or special devices |
|
|
1754 | (for example, C<epoll> on Linux works with F</dev/random> but not with |
|
|
1755 | F</dev/urandom>), and even though the file might better be served with |
|
|
1756 | asynchronous I/O instead of with non-blocking I/O, it is still useful when |
|
|
1757 | it "just works" instead of freezing. |
|
|
1758 | |
|
|
1759 | So avoid file descriptors pointing to files when you know it (e.g. use |
|
|
1760 | libeio), but use them when it is convenient, e.g. for STDIN/STDOUT, or |
|
|
1761 | when you rarely read from a file instead of from a socket, and want to |
|
|
1762 | reuse the same code path. |
|
|
1763 | |
1476 | =head3 The special problem of fork |
1764 | =head3 The special problem of fork |
1477 | |
1765 | |
1478 | Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit |
1766 | Some backends (epoll, kqueue, linuxaio, iouring) do not support C<fork ()> |
1479 | useless behaviour. Libev fully supports fork, but needs to be told about |
1767 | at all or exhibit useless behaviour. Libev fully supports fork, but needs |
1480 | it in the child. |
1768 | to be told about it in the child if you want to continue to use it in the |
|
|
1769 | child. |
1481 | |
1770 | |
1482 | To support fork in your programs, you either have to call |
1771 | To support fork in your child processes, you have to call C<ev_loop_fork |
1483 | C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child, |
1772 | ()> after a fork in the child, enable C<EVFLAG_FORKCHECK>, or resort to |
1484 | enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or |
1773 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
1485 | C<EVBACKEND_POLL>. |
|
|
1486 | |
1774 | |
1487 | =head3 The special problem of SIGPIPE |
1775 | =head3 The special problem of SIGPIPE |
1488 | |
1776 | |
1489 | While not really specific to libev, it is easy to forget about C<SIGPIPE>: |
1777 | While not really specific to libev, it is easy to forget about C<SIGPIPE>: |
1490 | when writing to a pipe whose other end has been closed, your program gets |
1778 | when writing to a pipe whose other end has been closed, your program gets |
… | |
… | |
1493 | |
1781 | |
1494 | So when you encounter spurious, unexplained daemon exits, make sure you |
1782 | So when you encounter spurious, unexplained daemon exits, make sure you |
1495 | ignore SIGPIPE (and maybe make sure you log the exit status of your daemon |
1783 | ignore SIGPIPE (and maybe make sure you log the exit status of your daemon |
1496 | somewhere, as that would have given you a big clue). |
1784 | somewhere, as that would have given you a big clue). |
1497 | |
1785 | |
|
|
1786 | =head3 The special problem of accept()ing when you can't |
|
|
1787 | |
|
|
1788 | Many implementations of the POSIX C<accept> function (for example, |
|
|
1789 | found in post-2004 Linux) have the peculiar behaviour of not removing a |
|
|
1790 | connection from the pending queue in all error cases. |
|
|
1791 | |
|
|
1792 | For example, larger servers often run out of file descriptors (because |
|
|
1793 | of resource limits), causing C<accept> to fail with C<ENFILE> but not |
|
|
1794 | rejecting the connection, leading to libev signalling readiness on |
|
|
1795 | the next iteration again (the connection still exists after all), and |
|
|
1796 | typically causing the program to loop at 100% CPU usage. |
|
|
1797 | |
|
|
1798 | Unfortunately, the set of errors that cause this issue differs between |
|
|
1799 | operating systems, there is usually little the app can do to remedy the |
|
|
1800 | situation, and no known thread-safe method of removing the connection to |
|
|
1801 | cope with overload is known (to me). |
|
|
1802 | |
|
|
1803 | One of the easiest ways to handle this situation is to just ignore it |
|
|
1804 | - when the program encounters an overload, it will just loop until the |
|
|
1805 | situation is over. While this is a form of busy waiting, no OS offers an |
|
|
1806 | event-based way to handle this situation, so it's the best one can do. |
|
|
1807 | |
|
|
1808 | A better way to handle the situation is to log any errors other than |
|
|
1809 | C<EAGAIN> and C<EWOULDBLOCK>, making sure not to flood the log with such |
|
|
1810 | messages, and continue as usual, which at least gives the user an idea of |
|
|
1811 | what could be wrong ("raise the ulimit!"). For extra points one could stop |
|
|
1812 | the C<ev_io> watcher on the listening fd "for a while", which reduces CPU |
|
|
1813 | usage. |
|
|
1814 | |
|
|
1815 | If your program is single-threaded, then you could also keep a dummy file |
|
|
1816 | descriptor for overload situations (e.g. by opening F</dev/null>), and |
|
|
1817 | when you run into C<ENFILE> or C<EMFILE>, close it, run C<accept>, |
|
|
1818 | close that fd, and create a new dummy fd. This will gracefully refuse |
|
|
1819 | clients under typical overload conditions. |
|
|
1820 | |
|
|
1821 | The last way to handle it is to simply log the error and C<exit>, as |
|
|
1822 | is often done with C<malloc> failures, but this results in an easy |
|
|
1823 | opportunity for a DoS attack. |
1498 | |
1824 | |
1499 | =head3 Watcher-Specific Functions |
1825 | =head3 Watcher-Specific Functions |
1500 | |
1826 | |
1501 | =over 4 |
1827 | =over 4 |
1502 | |
1828 | |
… | |
… | |
1506 | |
1832 | |
1507 | Configures an C<ev_io> watcher. The C<fd> is the file descriptor to |
1833 | Configures an C<ev_io> watcher. The C<fd> is the file descriptor to |
1508 | receive events for and C<events> is either C<EV_READ>, C<EV_WRITE> or |
1834 | receive events for and C<events> is either C<EV_READ>, C<EV_WRITE> or |
1509 | C<EV_READ | EV_WRITE>, to express the desire to receive the given events. |
1835 | C<EV_READ | EV_WRITE>, to express the desire to receive the given events. |
1510 | |
1836 | |
1511 | =item int fd [read-only] |
1837 | =item ev_io_modify (ev_io *, int events) |
1512 | |
1838 | |
1513 | The file descriptor being watched. |
1839 | Similar to C<ev_io_set>, but only changes the event mask. Using this might |
|
|
1840 | be faster with some backends, as libev can assume that the C<fd> still |
|
|
1841 | refers to the same underlying file description, something it cannot do |
|
|
1842 | when using C<ev_io_set>. |
1514 | |
1843 | |
|
|
1844 | =item int fd [no-modify] |
|
|
1845 | |
|
|
1846 | The file descriptor being watched. While it can be read at any time, you |
|
|
1847 | must not modify this member even when the watcher is stopped - always use |
|
|
1848 | C<ev_io_set> for that. |
|
|
1849 | |
1515 | =item int events [read-only] |
1850 | =item int events [no-modify] |
1516 | |
1851 | |
1517 | The events being watched. |
1852 | The set of events the fd is being watched for, among other flags. Remember |
|
|
1853 | that this is a bit set - to test for C<EV_READ>, use C<< w->events & |
|
|
1854 | EV_READ >>, and similarly for C<EV_WRITE>. |
|
|
1855 | |
|
|
1856 | As with C<fd>, you must not modify this member even when the watcher is |
|
|
1857 | stopped, always use C<ev_io_set> or C<ev_io_modify> for that. |
1518 | |
1858 | |
1519 | =back |
1859 | =back |
1520 | |
1860 | |
1521 | =head3 Examples |
1861 | =head3 Examples |
1522 | |
1862 | |
… | |
… | |
1534 | ... |
1874 | ... |
1535 | struct ev_loop *loop = ev_default_init (0); |
1875 | struct ev_loop *loop = ev_default_init (0); |
1536 | ev_io stdin_readable; |
1876 | ev_io stdin_readable; |
1537 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1877 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1538 | ev_io_start (loop, &stdin_readable); |
1878 | ev_io_start (loop, &stdin_readable); |
1539 | ev_loop (loop, 0); |
1879 | ev_run (loop, 0); |
1540 | |
1880 | |
1541 | |
1881 | |
1542 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
1882 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
1543 | |
1883 | |
1544 | Timer watchers are simple relative timers that generate an event after a |
1884 | Timer watchers are simple relative timers that generate an event after a |
… | |
… | |
1550 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1890 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1551 | monotonic clock option helps a lot here). |
1891 | monotonic clock option helps a lot here). |
1552 | |
1892 | |
1553 | The callback is guaranteed to be invoked only I<after> its timeout has |
1893 | The callback is guaranteed to be invoked only I<after> its timeout has |
1554 | passed (not I<at>, so on systems with very low-resolution clocks this |
1894 | passed (not I<at>, so on systems with very low-resolution clocks this |
1555 | might introduce a small delay). If multiple timers become ready during the |
1895 | might introduce a small delay, see "the special problem of being too |
|
|
1896 | early", below). If multiple timers become ready during the same loop |
1556 | same loop iteration then the ones with earlier time-out values are invoked |
1897 | iteration then the ones with earlier time-out values are invoked before |
1557 | before ones of the same priority with later time-out values (but this is |
1898 | ones of the same priority with later time-out values (but this is no |
1558 | no longer true when a callback calls C<ev_loop> recursively). |
1899 | longer true when a callback calls C<ev_run> recursively). |
1559 | |
1900 | |
1560 | =head3 Be smart about timeouts |
1901 | =head3 Be smart about timeouts |
1561 | |
1902 | |
1562 | Many real-world problems involve some kind of timeout, usually for error |
1903 | Many real-world problems involve some kind of timeout, usually for error |
1563 | recovery. A typical example is an HTTP request - if the other side hangs, |
1904 | recovery. A typical example is an HTTP request - if the other side hangs, |
… | |
… | |
1638 | |
1979 | |
1639 | In this case, it would be more efficient to leave the C<ev_timer> alone, |
1980 | In this case, it would be more efficient to leave the C<ev_timer> alone, |
1640 | but remember the time of last activity, and check for a real timeout only |
1981 | but remember the time of last activity, and check for a real timeout only |
1641 | within the callback: |
1982 | within the callback: |
1642 | |
1983 | |
|
|
1984 | ev_tstamp timeout = 60.; |
1643 | ev_tstamp last_activity; // time of last activity |
1985 | ev_tstamp last_activity; // time of last activity |
|
|
1986 | ev_timer timer; |
1644 | |
1987 | |
1645 | static void |
1988 | static void |
1646 | callback (EV_P_ ev_timer *w, int revents) |
1989 | callback (EV_P_ ev_timer *w, int revents) |
1647 | { |
1990 | { |
1648 | ev_tstamp now = ev_now (EV_A); |
1991 | // calculate when the timeout would happen |
1649 | ev_tstamp timeout = last_activity + 60.; |
1992 | ev_tstamp after = last_activity - ev_now (EV_A) + timeout; |
1650 | |
1993 | |
1651 | // if last_activity + 60. is older than now, we did time out |
1994 | // if negative, it means we the timeout already occurred |
1652 | if (timeout < now) |
1995 | if (after < 0.) |
1653 | { |
1996 | { |
1654 | // timeout occured, take action |
1997 | // timeout occurred, take action |
1655 | } |
1998 | } |
1656 | else |
1999 | else |
1657 | { |
2000 | { |
1658 | // callback was invoked, but there was some activity, re-arm |
2001 | // callback was invoked, but there was some recent |
1659 | // the watcher to fire in last_activity + 60, which is |
2002 | // activity. simply restart the timer to time out |
1660 | // guaranteed to be in the future, so "again" is positive: |
2003 | // after "after" seconds, which is the earliest time |
1661 | w->repeat = timeout - now; |
2004 | // the timeout can occur. |
|
|
2005 | ev_timer_set (w, after, 0.); |
1662 | ev_timer_again (EV_A_ w); |
2006 | ev_timer_start (EV_A_ w); |
1663 | } |
2007 | } |
1664 | } |
2008 | } |
1665 | |
2009 | |
1666 | To summarise the callback: first calculate the real timeout (defined |
2010 | To summarise the callback: first calculate in how many seconds the |
1667 | as "60 seconds after the last activity"), then check if that time has |
2011 | timeout will occur (by calculating the absolute time when it would occur, |
1668 | been reached, which means something I<did>, in fact, time out. Otherwise |
2012 | C<last_activity + timeout>, and subtracting the current time, C<ev_now |
1669 | the callback was invoked too early (C<timeout> is in the future), so |
2013 | (EV_A)> from that). |
1670 | re-schedule the timer to fire at that future time, to see if maybe we have |
|
|
1671 | a timeout then. |
|
|
1672 | |
2014 | |
1673 | Note how C<ev_timer_again> is used, taking advantage of the |
2015 | If this value is negative, then we are already past the timeout, i.e. we |
1674 | C<ev_timer_again> optimisation when the timer is already running. |
2016 | timed out, and need to do whatever is needed in this case. |
|
|
2017 | |
|
|
2018 | Otherwise, we now the earliest time at which the timeout would trigger, |
|
|
2019 | and simply start the timer with this timeout value. |
|
|
2020 | |
|
|
2021 | In other words, each time the callback is invoked it will check whether |
|
|
2022 | the timeout occurred. If not, it will simply reschedule itself to check |
|
|
2023 | again at the earliest time it could time out. Rinse. Repeat. |
1675 | |
2024 | |
1676 | This scheme causes more callback invocations (about one every 60 seconds |
2025 | This scheme causes more callback invocations (about one every 60 seconds |
1677 | minus half the average time between activity), but virtually no calls to |
2026 | minus half the average time between activity), but virtually no calls to |
1678 | libev to change the timeout. |
2027 | libev to change the timeout. |
1679 | |
2028 | |
1680 | To start the timer, simply initialise the watcher and set C<last_activity> |
2029 | To start the machinery, simply initialise the watcher and set |
1681 | to the current time (meaning we just have some activity :), then call the |
2030 | C<last_activity> to the current time (meaning there was some activity just |
1682 | callback, which will "do the right thing" and start the timer: |
2031 | now), then call the callback, which will "do the right thing" and start |
|
|
2032 | the timer: |
1683 | |
2033 | |
|
|
2034 | last_activity = ev_now (EV_A); |
1684 | ev_init (timer, callback); |
2035 | ev_init (&timer, callback); |
1685 | last_activity = ev_now (loop); |
2036 | callback (EV_A_ &timer, 0); |
1686 | callback (loop, timer, EV_TIMEOUT); |
|
|
1687 | |
2037 | |
1688 | And when there is some activity, simply store the current time in |
2038 | When there is some activity, simply store the current time in |
1689 | C<last_activity>, no libev calls at all: |
2039 | C<last_activity>, no libev calls at all: |
1690 | |
2040 | |
|
|
2041 | if (activity detected) |
1691 | last_actiivty = ev_now (loop); |
2042 | last_activity = ev_now (EV_A); |
|
|
2043 | |
|
|
2044 | When your timeout value changes, then the timeout can be changed by simply |
|
|
2045 | providing a new value, stopping the timer and calling the callback, which |
|
|
2046 | will again do the right thing (for example, time out immediately :). |
|
|
2047 | |
|
|
2048 | timeout = new_value; |
|
|
2049 | ev_timer_stop (EV_A_ &timer); |
|
|
2050 | callback (EV_A_ &timer, 0); |
1692 | |
2051 | |
1693 | This technique is slightly more complex, but in most cases where the |
2052 | This technique is slightly more complex, but in most cases where the |
1694 | time-out is unlikely to be triggered, much more efficient. |
2053 | time-out is unlikely to be triggered, much more efficient. |
1695 | |
|
|
1696 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
|
|
1697 | callback :) - just change the timeout and invoke the callback, which will |
|
|
1698 | fix things for you. |
|
|
1699 | |
2054 | |
1700 | =item 4. Wee, just use a double-linked list for your timeouts. |
2055 | =item 4. Wee, just use a double-linked list for your timeouts. |
1701 | |
2056 | |
1702 | If there is not one request, but many thousands (millions...), all |
2057 | If there is not one request, but many thousands (millions...), all |
1703 | employing some kind of timeout with the same timeout value, then one can |
2058 | employing some kind of timeout with the same timeout value, then one can |
… | |
… | |
1730 | Method #1 is almost always a bad idea, and buys you nothing. Method #4 is |
2085 | Method #1 is almost always a bad idea, and buys you nothing. Method #4 is |
1731 | rather complicated, but extremely efficient, something that really pays |
2086 | rather complicated, but extremely efficient, something that really pays |
1732 | off after the first million or so of active timers, i.e. it's usually |
2087 | off after the first million or so of active timers, i.e. it's usually |
1733 | overkill :) |
2088 | overkill :) |
1734 | |
2089 | |
|
|
2090 | =head3 The special problem of being too early |
|
|
2091 | |
|
|
2092 | If you ask a timer to call your callback after three seconds, then |
|
|
2093 | you expect it to be invoked after three seconds - but of course, this |
|
|
2094 | cannot be guaranteed to infinite precision. Less obviously, it cannot be |
|
|
2095 | guaranteed to any precision by libev - imagine somebody suspending the |
|
|
2096 | process with a STOP signal for a few hours for example. |
|
|
2097 | |
|
|
2098 | So, libev tries to invoke your callback as soon as possible I<after> the |
|
|
2099 | delay has occurred, but cannot guarantee this. |
|
|
2100 | |
|
|
2101 | A less obvious failure mode is calling your callback too early: many event |
|
|
2102 | loops compare timestamps with a "elapsed delay >= requested delay", but |
|
|
2103 | this can cause your callback to be invoked much earlier than you would |
|
|
2104 | expect. |
|
|
2105 | |
|
|
2106 | To see why, imagine a system with a clock that only offers full second |
|
|
2107 | resolution (think windows if you can't come up with a broken enough OS |
|
|
2108 | yourself). If you schedule a one-second timer at the time 500.9, then the |
|
|
2109 | event loop will schedule your timeout to elapse at a system time of 500 |
|
|
2110 | (500.9 truncated to the resolution) + 1, or 501. |
|
|
2111 | |
|
|
2112 | If an event library looks at the timeout 0.1s later, it will see "501 >= |
|
|
2113 | 501" and invoke the callback 0.1s after it was started, even though a |
|
|
2114 | one-second delay was requested - this is being "too early", despite best |
|
|
2115 | intentions. |
|
|
2116 | |
|
|
2117 | This is the reason why libev will never invoke the callback if the elapsed |
|
|
2118 | delay equals the requested delay, but only when the elapsed delay is |
|
|
2119 | larger than the requested delay. In the example above, libev would only invoke |
|
|
2120 | the callback at system time 502, or 1.1s after the timer was started. |
|
|
2121 | |
|
|
2122 | So, while libev cannot guarantee that your callback will be invoked |
|
|
2123 | exactly when requested, it I<can> and I<does> guarantee that the requested |
|
|
2124 | delay has actually elapsed, or in other words, it always errs on the "too |
|
|
2125 | late" side of things. |
|
|
2126 | |
1735 | =head3 The special problem of time updates |
2127 | =head3 The special problem of time updates |
1736 | |
2128 | |
1737 | Establishing the current time is a costly operation (it usually takes at |
2129 | Establishing the current time is a costly operation (it usually takes |
1738 | least two system calls): EV therefore updates its idea of the current |
2130 | at least one system call): EV therefore updates its idea of the current |
1739 | time only before and after C<ev_loop> collects new events, which causes a |
2131 | time only before and after C<ev_run> collects new events, which causes a |
1740 | growing difference between C<ev_now ()> and C<ev_time ()> when handling |
2132 | growing difference between C<ev_now ()> and C<ev_time ()> when handling |
1741 | lots of events in one iteration. |
2133 | lots of events in one iteration. |
1742 | |
2134 | |
1743 | The relative timeouts are calculated relative to the C<ev_now ()> |
2135 | The relative timeouts are calculated relative to the C<ev_now ()> |
1744 | time. This is usually the right thing as this timestamp refers to the time |
2136 | time. This is usually the right thing as this timestamp refers to the time |
1745 | of the event triggering whatever timeout you are modifying/starting. If |
2137 | of the event triggering whatever timeout you are modifying/starting. If |
1746 | you suspect event processing to be delayed and you I<need> to base the |
2138 | you suspect event processing to be delayed and you I<need> to base the |
1747 | timeout on the current time, use something like this to adjust for this: |
2139 | timeout on the current time, use something like the following to adjust |
|
|
2140 | for it: |
1748 | |
2141 | |
1749 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
2142 | ev_timer_set (&timer, after + (ev_time () - ev_now ()), 0.); |
1750 | |
2143 | |
1751 | If the event loop is suspended for a long time, you can also force an |
2144 | If the event loop is suspended for a long time, you can also force an |
1752 | update of the time returned by C<ev_now ()> by calling C<ev_now_update |
2145 | update of the time returned by C<ev_now ()> by calling C<ev_now_update |
1753 | ()>. |
2146 | ()>, although that will push the event time of all outstanding events |
|
|
2147 | further into the future. |
|
|
2148 | |
|
|
2149 | =head3 The special problem of unsynchronised clocks |
|
|
2150 | |
|
|
2151 | Modern systems have a variety of clocks - libev itself uses the normal |
|
|
2152 | "wall clock" clock and, if available, the monotonic clock (to avoid time |
|
|
2153 | jumps). |
|
|
2154 | |
|
|
2155 | Neither of these clocks is synchronised with each other or any other clock |
|
|
2156 | on the system, so C<ev_time ()> might return a considerably different time |
|
|
2157 | than C<gettimeofday ()> or C<time ()>. On a GNU/Linux system, for example, |
|
|
2158 | a call to C<gettimeofday> might return a second count that is one higher |
|
|
2159 | than a directly following call to C<time>. |
|
|
2160 | |
|
|
2161 | The moral of this is to only compare libev-related timestamps with |
|
|
2162 | C<ev_time ()> and C<ev_now ()>, at least if you want better precision than |
|
|
2163 | a second or so. |
|
|
2164 | |
|
|
2165 | One more problem arises due to this lack of synchronisation: if libev uses |
|
|
2166 | the system monotonic clock and you compare timestamps from C<ev_time> |
|
|
2167 | or C<ev_now> from when you started your timer and when your callback is |
|
|
2168 | invoked, you will find that sometimes the callback is a bit "early". |
|
|
2169 | |
|
|
2170 | This is because C<ev_timer>s work in real time, not wall clock time, so |
|
|
2171 | libev makes sure your callback is not invoked before the delay happened, |
|
|
2172 | I<measured according to the real time>, not the system clock. |
|
|
2173 | |
|
|
2174 | If your timeouts are based on a physical timescale (e.g. "time out this |
|
|
2175 | connection after 100 seconds") then this shouldn't bother you as it is |
|
|
2176 | exactly the right behaviour. |
|
|
2177 | |
|
|
2178 | If you want to compare wall clock/system timestamps to your timers, then |
|
|
2179 | you need to use C<ev_periodic>s, as these are based on the wall clock |
|
|
2180 | time, where your comparisons will always generate correct results. |
|
|
2181 | |
|
|
2182 | =head3 The special problems of suspended animation |
|
|
2183 | |
|
|
2184 | When you leave the server world it is quite customary to hit machines that |
|
|
2185 | can suspend/hibernate - what happens to the clocks during such a suspend? |
|
|
2186 | |
|
|
2187 | Some quick tests made with a Linux 2.6.28 indicate that a suspend freezes |
|
|
2188 | all processes, while the clocks (C<times>, C<CLOCK_MONOTONIC>) continue |
|
|
2189 | to run until the system is suspended, but they will not advance while the |
|
|
2190 | system is suspended. That means, on resume, it will be as if the program |
|
|
2191 | was frozen for a few seconds, but the suspend time will not be counted |
|
|
2192 | towards C<ev_timer> when a monotonic clock source is used. The real time |
|
|
2193 | clock advanced as expected, but if it is used as sole clocksource, then a |
|
|
2194 | long suspend would be detected as a time jump by libev, and timers would |
|
|
2195 | be adjusted accordingly. |
|
|
2196 | |
|
|
2197 | I would not be surprised to see different behaviour in different between |
|
|
2198 | operating systems, OS versions or even different hardware. |
|
|
2199 | |
|
|
2200 | The other form of suspend (job control, or sending a SIGSTOP) will see a |
|
|
2201 | time jump in the monotonic clocks and the realtime clock. If the program |
|
|
2202 | is suspended for a very long time, and monotonic clock sources are in use, |
|
|
2203 | then you can expect C<ev_timer>s to expire as the full suspension time |
|
|
2204 | will be counted towards the timers. When no monotonic clock source is in |
|
|
2205 | use, then libev will again assume a timejump and adjust accordingly. |
|
|
2206 | |
|
|
2207 | It might be beneficial for this latter case to call C<ev_suspend> |
|
|
2208 | and C<ev_resume> in code that handles C<SIGTSTP>, to at least get |
|
|
2209 | deterministic behaviour in this case (you can do nothing against |
|
|
2210 | C<SIGSTOP>). |
1754 | |
2211 | |
1755 | =head3 Watcher-Specific Functions and Data Members |
2212 | =head3 Watcher-Specific Functions and Data Members |
1756 | |
2213 | |
1757 | =over 4 |
2214 | =over 4 |
1758 | |
2215 | |
1759 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
2216 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
1760 | |
2217 | |
1761 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
2218 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
1762 | |
2219 | |
1763 | Configure the timer to trigger after C<after> seconds. If C<repeat> |
2220 | Configure the timer to trigger after C<after> seconds (fractional and |
1764 | is C<0.>, then it will automatically be stopped once the timeout is |
2221 | negative values are supported). If C<repeat> is C<0.>, then it will |
1765 | reached. If it is positive, then the timer will automatically be |
2222 | automatically be stopped once the timeout is reached. If it is positive, |
1766 | configured to trigger again C<repeat> seconds later, again, and again, |
2223 | then the timer will automatically be configured to trigger again C<repeat> |
1767 | until stopped manually. |
2224 | seconds later, again, and again, until stopped manually. |
1768 | |
2225 | |
1769 | The timer itself will do a best-effort at avoiding drift, that is, if |
2226 | The timer itself will do a best-effort at avoiding drift, that is, if |
1770 | you configure a timer to trigger every 10 seconds, then it will normally |
2227 | you configure a timer to trigger every 10 seconds, then it will normally |
1771 | trigger at exactly 10 second intervals. If, however, your program cannot |
2228 | trigger at exactly 10 second intervals. If, however, your program cannot |
1772 | keep up with the timer (because it takes longer than those 10 seconds to |
2229 | keep up with the timer (because it takes longer than those 10 seconds to |
1773 | do stuff) the timer will not fire more than once per event loop iteration. |
2230 | do stuff) the timer will not fire more than once per event loop iteration. |
1774 | |
2231 | |
1775 | =item ev_timer_again (loop, ev_timer *) |
2232 | =item ev_timer_again (loop, ev_timer *) |
1776 | |
2233 | |
1777 | This will act as if the timer timed out and restart it again if it is |
2234 | This will act as if the timer timed out, and restarts it again if it is |
1778 | repeating. The exact semantics are: |
2235 | repeating. It basically works like calling C<ev_timer_stop>, updating the |
|
|
2236 | timeout to the C<repeat> value and calling C<ev_timer_start>. |
1779 | |
2237 | |
|
|
2238 | The exact semantics are as in the following rules, all of which will be |
|
|
2239 | applied to the watcher: |
|
|
2240 | |
|
|
2241 | =over 4 |
|
|
2242 | |
1780 | If the timer is pending, its pending status is cleared. |
2243 | =item If the timer is pending, the pending status is always cleared. |
1781 | |
2244 | |
1782 | If the timer is started but non-repeating, stop it (as if it timed out). |
2245 | =item If the timer is started but non-repeating, stop it (as if it timed |
|
|
2246 | out, without invoking it). |
1783 | |
2247 | |
1784 | If the timer is repeating, either start it if necessary (with the |
2248 | =item If the timer is repeating, make the C<repeat> value the new timeout |
1785 | C<repeat> value), or reset the running timer to the C<repeat> value. |
2249 | and start the timer, if necessary. |
1786 | |
2250 | |
|
|
2251 | =back |
|
|
2252 | |
1787 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
2253 | This sounds a bit complicated, see L</Be smart about timeouts>, above, for a |
1788 | usage example. |
2254 | usage example. |
|
|
2255 | |
|
|
2256 | =item ev_tstamp ev_timer_remaining (loop, ev_timer *) |
|
|
2257 | |
|
|
2258 | Returns the remaining time until a timer fires. If the timer is active, |
|
|
2259 | then this time is relative to the current event loop time, otherwise it's |
|
|
2260 | the timeout value currently configured. |
|
|
2261 | |
|
|
2262 | That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns |
|
|
2263 | C<5>. When the timer is started and one second passes, C<ev_timer_remaining> |
|
|
2264 | will return C<4>. When the timer expires and is restarted, it will return |
|
|
2265 | roughly C<7> (likely slightly less as callback invocation takes some time, |
|
|
2266 | too), and so on. |
1789 | |
2267 | |
1790 | =item ev_tstamp repeat [read-write] |
2268 | =item ev_tstamp repeat [read-write] |
1791 | |
2269 | |
1792 | The current C<repeat> value. Will be used each time the watcher times out |
2270 | The current C<repeat> value. Will be used each time the watcher times out |
1793 | or C<ev_timer_again> is called, and determines the next timeout (if any), |
2271 | or C<ev_timer_again> is called, and determines the next timeout (if any), |
… | |
… | |
1819 | } |
2297 | } |
1820 | |
2298 | |
1821 | ev_timer mytimer; |
2299 | ev_timer mytimer; |
1822 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
2300 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1823 | ev_timer_again (&mytimer); /* start timer */ |
2301 | ev_timer_again (&mytimer); /* start timer */ |
1824 | ev_loop (loop, 0); |
2302 | ev_run (loop, 0); |
1825 | |
2303 | |
1826 | // and in some piece of code that gets executed on any "activity": |
2304 | // and in some piece of code that gets executed on any "activity": |
1827 | // reset the timeout to start ticking again at 10 seconds |
2305 | // reset the timeout to start ticking again at 10 seconds |
1828 | ev_timer_again (&mytimer); |
2306 | ev_timer_again (&mytimer); |
1829 | |
2307 | |
… | |
… | |
1833 | Periodic watchers are also timers of a kind, but they are very versatile |
2311 | Periodic watchers are also timers of a kind, but they are very versatile |
1834 | (and unfortunately a bit complex). |
2312 | (and unfortunately a bit complex). |
1835 | |
2313 | |
1836 | Unlike C<ev_timer>, periodic watchers are not based on real time (or |
2314 | Unlike C<ev_timer>, periodic watchers are not based on real time (or |
1837 | relative time, the physical time that passes) but on wall clock time |
2315 | relative time, the physical time that passes) but on wall clock time |
1838 | (absolute time, the thing you can read on your calender or clock). The |
2316 | (absolute time, the thing you can read on your calendar or clock). The |
1839 | difference is that wall clock time can run faster or slower than real |
2317 | difference is that wall clock time can run faster or slower than real |
1840 | time, and time jumps are not uncommon (e.g. when you adjust your |
2318 | time, and time jumps are not uncommon (e.g. when you adjust your |
1841 | wrist-watch). |
2319 | wrist-watch). |
1842 | |
2320 | |
1843 | You can tell a periodic watcher to trigger after some specific point |
2321 | You can tell a periodic watcher to trigger after some specific point |
… | |
… | |
1848 | C<ev_timer>, which would still trigger roughly 10 seconds after starting |
2326 | C<ev_timer>, which would still trigger roughly 10 seconds after starting |
1849 | it, as it uses a relative timeout). |
2327 | it, as it uses a relative timeout). |
1850 | |
2328 | |
1851 | C<ev_periodic> watchers can also be used to implement vastly more complex |
2329 | C<ev_periodic> watchers can also be used to implement vastly more complex |
1852 | timers, such as triggering an event on each "midnight, local time", or |
2330 | timers, such as triggering an event on each "midnight, local time", or |
1853 | other complicated rules. This cannot be done with C<ev_timer> watchers, as |
2331 | other complicated rules. This cannot easily be done with C<ev_timer> |
1854 | those cannot react to time jumps. |
2332 | watchers, as those cannot react to time jumps. |
1855 | |
2333 | |
1856 | As with timers, the callback is guaranteed to be invoked only when the |
2334 | As with timers, the callback is guaranteed to be invoked only when the |
1857 | point in time where it is supposed to trigger has passed. If multiple |
2335 | point in time where it is supposed to trigger has passed. If multiple |
1858 | timers become ready during the same loop iteration then the ones with |
2336 | timers become ready during the same loop iteration then the ones with |
1859 | earlier time-out values are invoked before ones with later time-out values |
2337 | earlier time-out values are invoked before ones with later time-out values |
1860 | (but this is no longer true when a callback calls C<ev_loop> recursively). |
2338 | (but this is no longer true when a callback calls C<ev_run> recursively). |
1861 | |
2339 | |
1862 | =head3 Watcher-Specific Functions and Data Members |
2340 | =head3 Watcher-Specific Functions and Data Members |
1863 | |
2341 | |
1864 | =over 4 |
2342 | =over 4 |
1865 | |
2343 | |
… | |
… | |
1900 | |
2378 | |
1901 | Another way to think about it (for the mathematically inclined) is that |
2379 | Another way to think about it (for the mathematically inclined) is that |
1902 | C<ev_periodic> will try to run the callback in this mode at the next possible |
2380 | C<ev_periodic> will try to run the callback in this mode at the next possible |
1903 | time where C<time = offset (mod interval)>, regardless of any time jumps. |
2381 | time where C<time = offset (mod interval)>, regardless of any time jumps. |
1904 | |
2382 | |
1905 | For numerical stability it is preferable that the C<offset> value is near |
2383 | The C<interval> I<MUST> be positive, and for numerical stability, the |
1906 | C<ev_now ()> (the current time), but there is no range requirement for |
2384 | interval value should be higher than C<1/8192> (which is around 100 |
1907 | this value, and in fact is often specified as zero. |
2385 | microseconds) and C<offset> should be higher than C<0> and should have |
|
|
2386 | at most a similar magnitude as the current time (say, within a factor of |
|
|
2387 | ten). Typical values for offset are, in fact, C<0> or something between |
|
|
2388 | C<0> and C<interval>, which is also the recommended range. |
1908 | |
2389 | |
1909 | Note also that there is an upper limit to how often a timer can fire (CPU |
2390 | Note also that there is an upper limit to how often a timer can fire (CPU |
1910 | speed for example), so if C<interval> is very small then timing stability |
2391 | speed for example), so if C<interval> is very small then timing stability |
1911 | will of course deteriorate. Libev itself tries to be exact to be about one |
2392 | will of course deteriorate. Libev itself tries to be exact to be about one |
1912 | millisecond (if the OS supports it and the machine is fast enough). |
2393 | millisecond (if the OS supports it and the machine is fast enough). |
… | |
… | |
1942 | |
2423 | |
1943 | NOTE: I<< This callback must always return a time that is higher than or |
2424 | NOTE: I<< This callback must always return a time that is higher than or |
1944 | equal to the passed C<now> value >>. |
2425 | equal to the passed C<now> value >>. |
1945 | |
2426 | |
1946 | This can be used to create very complex timers, such as a timer that |
2427 | This can be used to create very complex timers, such as a timer that |
1947 | triggers on "next midnight, local time". To do this, you would calculate the |
2428 | triggers on "next midnight, local time". To do this, you would calculate |
1948 | next midnight after C<now> and return the timestamp value for this. How |
2429 | the next midnight after C<now> and return the timestamp value for |
1949 | you do this is, again, up to you (but it is not trivial, which is the main |
2430 | this. Here is a (completely untested, no error checking) example on how to |
1950 | reason I omitted it as an example). |
2431 | do this: |
|
|
2432 | |
|
|
2433 | #include <time.h> |
|
|
2434 | |
|
|
2435 | static ev_tstamp |
|
|
2436 | my_rescheduler (ev_periodic *w, ev_tstamp now) |
|
|
2437 | { |
|
|
2438 | time_t tnow = (time_t)now; |
|
|
2439 | struct tm tm; |
|
|
2440 | localtime_r (&tnow, &tm); |
|
|
2441 | |
|
|
2442 | tm.tm_sec = tm.tm_min = tm.tm_hour = 0; // midnight current day |
|
|
2443 | ++tm.tm_mday; // midnight next day |
|
|
2444 | |
|
|
2445 | return mktime (&tm); |
|
|
2446 | } |
|
|
2447 | |
|
|
2448 | Note: this code might run into trouble on days that have more then two |
|
|
2449 | midnights (beginning and end). |
1951 | |
2450 | |
1952 | =back |
2451 | =back |
1953 | |
2452 | |
1954 | =item ev_periodic_again (loop, ev_periodic *) |
2453 | =item ev_periodic_again (loop, ev_periodic *) |
1955 | |
2454 | |
… | |
… | |
1993 | Example: Call a callback every hour, or, more precisely, whenever the |
2492 | Example: Call a callback every hour, or, more precisely, whenever the |
1994 | system time is divisible by 3600. The callback invocation times have |
2493 | system time is divisible by 3600. The callback invocation times have |
1995 | potentially a lot of jitter, but good long-term stability. |
2494 | potentially a lot of jitter, but good long-term stability. |
1996 | |
2495 | |
1997 | static void |
2496 | static void |
1998 | clock_cb (struct ev_loop *loop, ev_io *w, int revents) |
2497 | clock_cb (struct ev_loop *loop, ev_periodic *w, int revents) |
1999 | { |
2498 | { |
2000 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
2499 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
2001 | } |
2500 | } |
2002 | |
2501 | |
2003 | ev_periodic hourly_tick; |
2502 | ev_periodic hourly_tick; |
… | |
… | |
2020 | |
2519 | |
2021 | ev_periodic hourly_tick; |
2520 | ev_periodic hourly_tick; |
2022 | ev_periodic_init (&hourly_tick, clock_cb, |
2521 | ev_periodic_init (&hourly_tick, clock_cb, |
2023 | fmod (ev_now (loop), 3600.), 3600., 0); |
2522 | fmod (ev_now (loop), 3600.), 3600., 0); |
2024 | ev_periodic_start (loop, &hourly_tick); |
2523 | ev_periodic_start (loop, &hourly_tick); |
2025 | |
2524 | |
2026 | |
2525 | |
2027 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
2526 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
2028 | |
2527 | |
2029 | Signal watchers will trigger an event when the process receives a specific |
2528 | Signal watchers will trigger an event when the process receives a specific |
2030 | signal one or more times. Even though signals are very asynchronous, libev |
2529 | signal one or more times. Even though signals are very asynchronous, libev |
2031 | will try it's best to deliver signals synchronously, i.e. as part of the |
2530 | will try its best to deliver signals synchronously, i.e. as part of the |
2032 | normal event processing, like any other event. |
2531 | normal event processing, like any other event. |
2033 | |
2532 | |
2034 | If you want signals asynchronously, just use C<sigaction> as you would |
2533 | If you want signals to be delivered truly asynchronously, just use |
2035 | do without libev and forget about sharing the signal. You can even use |
2534 | C<sigaction> as you would do without libev and forget about sharing |
2036 | C<ev_async> from a signal handler to synchronously wake up an event loop. |
2535 | the signal. You can even use C<ev_async> from a signal handler to |
|
|
2536 | synchronously wake up an event loop. |
2037 | |
2537 | |
2038 | You can configure as many watchers as you like per signal. Only when the |
2538 | You can configure as many watchers as you like for the same signal, but |
2039 | first watcher gets started will libev actually register a signal handler |
2539 | only within the same loop, i.e. you can watch for C<SIGINT> in your |
2040 | with the kernel (thus it coexists with your own signal handlers as long as |
2540 | default loop and for C<SIGIO> in another loop, but you cannot watch for |
2041 | you don't register any with libev for the same signal). Similarly, when |
2541 | C<SIGINT> in both the default loop and another loop at the same time. At |
2042 | the last signal watcher for a signal is stopped, libev will reset the |
2542 | the moment, C<SIGCHLD> is permanently tied to the default loop. |
2043 | signal handler to SIG_DFL (regardless of what it was set to before). |
2543 | |
|
|
2544 | Only after the first watcher for a signal is started will libev actually |
|
|
2545 | register something with the kernel. It thus coexists with your own signal |
|
|
2546 | handlers as long as you don't register any with libev for the same signal. |
2044 | |
2547 | |
2045 | If possible and supported, libev will install its handlers with |
2548 | If possible and supported, libev will install its handlers with |
2046 | C<SA_RESTART> behaviour enabled, so system calls should not be unduly |
2549 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2047 | interrupted. If you have a problem with system calls getting interrupted by |
2550 | not be unduly interrupted. If you have a problem with system calls getting |
2048 | signals you can block all signals in an C<ev_check> watcher and unblock |
2551 | interrupted by signals you can block all signals in an C<ev_check> watcher |
2049 | them in an C<ev_prepare> watcher. |
2552 | and unblock them in an C<ev_prepare> watcher. |
|
|
2553 | |
|
|
2554 | =head3 The special problem of inheritance over fork/execve/pthread_create |
|
|
2555 | |
|
|
2556 | Both the signal mask (C<sigprocmask>) and the signal disposition |
|
|
2557 | (C<sigaction>) are unspecified after starting a signal watcher (and after |
|
|
2558 | stopping it again), that is, libev might or might not block the signal, |
|
|
2559 | and might or might not set or restore the installed signal handler (but |
|
|
2560 | see C<EVFLAG_NOSIGMASK>). |
|
|
2561 | |
|
|
2562 | While this does not matter for the signal disposition (libev never |
|
|
2563 | sets signals to C<SIG_IGN>, so handlers will be reset to C<SIG_DFL> on |
|
|
2564 | C<execve>), this matters for the signal mask: many programs do not expect |
|
|
2565 | certain signals to be blocked. |
|
|
2566 | |
|
|
2567 | This means that before calling C<exec> (from the child) you should reset |
|
|
2568 | the signal mask to whatever "default" you expect (all clear is a good |
|
|
2569 | choice usually). |
|
|
2570 | |
|
|
2571 | The simplest way to ensure that the signal mask is reset in the child is |
|
|
2572 | to install a fork handler with C<pthread_atfork> that resets it. That will |
|
|
2573 | catch fork calls done by libraries (such as the libc) as well. |
|
|
2574 | |
|
|
2575 | In current versions of libev, the signal will not be blocked indefinitely |
|
|
2576 | unless you use the C<signalfd> API (C<EV_SIGNALFD>). While this reduces |
|
|
2577 | the window of opportunity for problems, it will not go away, as libev |
|
|
2578 | I<has> to modify the signal mask, at least temporarily. |
|
|
2579 | |
|
|
2580 | So I can't stress this enough: I<If you do not reset your signal mask when |
|
|
2581 | you expect it to be empty, you have a race condition in your code>. This |
|
|
2582 | is not a libev-specific thing, this is true for most event libraries. |
|
|
2583 | |
|
|
2584 | =head3 The special problem of threads signal handling |
|
|
2585 | |
|
|
2586 | POSIX threads has problematic signal handling semantics, specifically, |
|
|
2587 | a lot of functionality (sigfd, sigwait etc.) only really works if all |
|
|
2588 | threads in a process block signals, which is hard to achieve. |
|
|
2589 | |
|
|
2590 | When you want to use sigwait (or mix libev signal handling with your own |
|
|
2591 | for the same signals), you can tackle this problem by globally blocking |
|
|
2592 | all signals before creating any threads (or creating them with a fully set |
|
|
2593 | sigprocmask) and also specifying the C<EVFLAG_NOSIGMASK> when creating |
|
|
2594 | loops. Then designate one thread as "signal receiver thread" which handles |
|
|
2595 | these signals. You can pass on any signals that libev might be interested |
|
|
2596 | in by calling C<ev_feed_signal>. |
2050 | |
2597 | |
2051 | =head3 Watcher-Specific Functions and Data Members |
2598 | =head3 Watcher-Specific Functions and Data Members |
2052 | |
2599 | |
2053 | =over 4 |
2600 | =over 4 |
2054 | |
2601 | |
… | |
… | |
2070 | Example: Try to exit cleanly on SIGINT. |
2617 | Example: Try to exit cleanly on SIGINT. |
2071 | |
2618 | |
2072 | static void |
2619 | static void |
2073 | sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2620 | sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2074 | { |
2621 | { |
2075 | ev_unloop (loop, EVUNLOOP_ALL); |
2622 | ev_break (loop, EVBREAK_ALL); |
2076 | } |
2623 | } |
2077 | |
2624 | |
2078 | ev_signal signal_watcher; |
2625 | ev_signal signal_watcher; |
2079 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
2626 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
2080 | ev_signal_start (loop, &signal_watcher); |
2627 | ev_signal_start (loop, &signal_watcher); |
… | |
… | |
2099 | libev) |
2646 | libev) |
2100 | |
2647 | |
2101 | =head3 Process Interaction |
2648 | =head3 Process Interaction |
2102 | |
2649 | |
2103 | Libev grabs C<SIGCHLD> as soon as the default event loop is |
2650 | Libev grabs C<SIGCHLD> as soon as the default event loop is |
2104 | initialised. This is necessary to guarantee proper behaviour even if |
2651 | initialised. This is necessary to guarantee proper behaviour even if the |
2105 | the first child watcher is started after the child exits. The occurrence |
2652 | first child watcher is started after the child exits. The occurrence |
2106 | of C<SIGCHLD> is recorded asynchronously, but child reaping is done |
2653 | of C<SIGCHLD> is recorded asynchronously, but child reaping is done |
2107 | synchronously as part of the event loop processing. Libev always reaps all |
2654 | synchronously as part of the event loop processing. Libev always reaps all |
2108 | children, even ones not watched. |
2655 | children, even ones not watched. |
2109 | |
2656 | |
2110 | =head3 Overriding the Built-In Processing |
2657 | =head3 Overriding the Built-In Processing |
… | |
… | |
2120 | =head3 Stopping the Child Watcher |
2667 | =head3 Stopping the Child Watcher |
2121 | |
2668 | |
2122 | Currently, the child watcher never gets stopped, even when the |
2669 | Currently, the child watcher never gets stopped, even when the |
2123 | child terminates, so normally one needs to stop the watcher in the |
2670 | child terminates, so normally one needs to stop the watcher in the |
2124 | callback. Future versions of libev might stop the watcher automatically |
2671 | callback. Future versions of libev might stop the watcher automatically |
2125 | when a child exit is detected. |
2672 | when a child exit is detected (calling C<ev_child_stop> twice is not a |
|
|
2673 | problem). |
2126 | |
2674 | |
2127 | =head3 Watcher-Specific Functions and Data Members |
2675 | =head3 Watcher-Specific Functions and Data Members |
2128 | |
2676 | |
2129 | =over 4 |
2677 | =over 4 |
2130 | |
2678 | |
… | |
… | |
2188 | |
2736 | |
2189 | =head2 C<ev_stat> - did the file attributes just change? |
2737 | =head2 C<ev_stat> - did the file attributes just change? |
2190 | |
2738 | |
2191 | This watches a file system path for attribute changes. That is, it calls |
2739 | This watches a file system path for attribute changes. That is, it calls |
2192 | C<stat> on that path in regular intervals (or when the OS says it changed) |
2740 | C<stat> on that path in regular intervals (or when the OS says it changed) |
2193 | and sees if it changed compared to the last time, invoking the callback if |
2741 | and sees if it changed compared to the last time, invoking the callback |
2194 | it did. |
2742 | if it did. Starting the watcher C<stat>'s the file, so only changes that |
|
|
2743 | happen after the watcher has been started will be reported. |
2195 | |
2744 | |
2196 | The path does not need to exist: changing from "path exists" to "path does |
2745 | The path does not need to exist: changing from "path exists" to "path does |
2197 | not exist" is a status change like any other. The condition "path does not |
2746 | not exist" is a status change like any other. The condition "path does not |
2198 | exist" (or more correctly "path cannot be stat'ed") is signified by the |
2747 | exist" (or more correctly "path cannot be stat'ed") is signified by the |
2199 | C<st_nlink> field being zero (which is otherwise always forced to be at |
2748 | C<st_nlink> field being zero (which is otherwise always forced to be at |
… | |
… | |
2429 | Apart from keeping your process non-blocking (which is a useful |
2978 | Apart from keeping your process non-blocking (which is a useful |
2430 | effect on its own sometimes), idle watchers are a good place to do |
2979 | effect on its own sometimes), idle watchers are a good place to do |
2431 | "pseudo-background processing", or delay processing stuff to after the |
2980 | "pseudo-background processing", or delay processing stuff to after the |
2432 | event loop has handled all outstanding events. |
2981 | event loop has handled all outstanding events. |
2433 | |
2982 | |
|
|
2983 | =head3 Abusing an C<ev_idle> watcher for its side-effect |
|
|
2984 | |
|
|
2985 | As long as there is at least one active idle watcher, libev will never |
|
|
2986 | sleep unnecessarily. Or in other words, it will loop as fast as possible. |
|
|
2987 | For this to work, the idle watcher doesn't need to be invoked at all - the |
|
|
2988 | lowest priority will do. |
|
|
2989 | |
|
|
2990 | This mode of operation can be useful together with an C<ev_check> watcher, |
|
|
2991 | to do something on each event loop iteration - for example to balance load |
|
|
2992 | between different connections. |
|
|
2993 | |
|
|
2994 | See L</Abusing an ev_check watcher for its side-effect> for a longer |
|
|
2995 | example. |
|
|
2996 | |
2434 | =head3 Watcher-Specific Functions and Data Members |
2997 | =head3 Watcher-Specific Functions and Data Members |
2435 | |
2998 | |
2436 | =over 4 |
2999 | =over 4 |
2437 | |
3000 | |
2438 | =item ev_idle_init (ev_idle *, callback) |
3001 | =item ev_idle_init (ev_idle *, callback) |
… | |
… | |
2449 | callback, free it. Also, use no error checking, as usual. |
3012 | callback, free it. Also, use no error checking, as usual. |
2450 | |
3013 | |
2451 | static void |
3014 | static void |
2452 | idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
3015 | idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
2453 | { |
3016 | { |
|
|
3017 | // stop the watcher |
|
|
3018 | ev_idle_stop (loop, w); |
|
|
3019 | |
|
|
3020 | // now we can free it |
2454 | free (w); |
3021 | free (w); |
|
|
3022 | |
2455 | // now do something you wanted to do when the program has |
3023 | // now do something you wanted to do when the program has |
2456 | // no longer anything immediate to do. |
3024 | // no longer anything immediate to do. |
2457 | } |
3025 | } |
2458 | |
3026 | |
2459 | ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
3027 | ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
… | |
… | |
2461 | ev_idle_start (loop, idle_watcher); |
3029 | ev_idle_start (loop, idle_watcher); |
2462 | |
3030 | |
2463 | |
3031 | |
2464 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
3032 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
2465 | |
3033 | |
2466 | Prepare and check watchers are usually (but not always) used in pairs: |
3034 | Prepare and check watchers are often (but not always) used in pairs: |
2467 | prepare watchers get invoked before the process blocks and check watchers |
3035 | prepare watchers get invoked before the process blocks and check watchers |
2468 | afterwards. |
3036 | afterwards. |
2469 | |
3037 | |
2470 | You I<must not> call C<ev_loop> or similar functions that enter |
3038 | You I<must not> call C<ev_run> (or similar functions that enter the |
2471 | the current event loop from either C<ev_prepare> or C<ev_check> |
3039 | current event loop) or C<ev_loop_fork> from either C<ev_prepare> or |
2472 | watchers. Other loops than the current one are fine, however. The |
3040 | C<ev_check> watchers. Other loops than the current one are fine, |
2473 | rationale behind this is that you do not need to check for recursion in |
3041 | however. The rationale behind this is that you do not need to check |
2474 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
3042 | for recursion in those watchers, i.e. the sequence will always be |
2475 | C<ev_check> so if you have one watcher of each kind they will always be |
3043 | C<ev_prepare>, blocking, C<ev_check> so if you have one watcher of each |
2476 | called in pairs bracketing the blocking call. |
3044 | kind they will always be called in pairs bracketing the blocking call. |
2477 | |
3045 | |
2478 | Their main purpose is to integrate other event mechanisms into libev and |
3046 | Their main purpose is to integrate other event mechanisms into libev and |
2479 | their use is somewhat advanced. They could be used, for example, to track |
3047 | their use is somewhat advanced. They could be used, for example, to track |
2480 | variable changes, implement your own watchers, integrate net-snmp or a |
3048 | variable changes, implement your own watchers, integrate net-snmp or a |
2481 | coroutine library and lots more. They are also occasionally useful if |
3049 | coroutine library and lots more. They are also occasionally useful if |
… | |
… | |
2499 | with priority higher than or equal to the event loop and one coroutine |
3067 | with priority higher than or equal to the event loop and one coroutine |
2500 | of lower priority, but only once, using idle watchers to keep the event |
3068 | of lower priority, but only once, using idle watchers to keep the event |
2501 | loop from blocking if lower-priority coroutines are active, thus mapping |
3069 | loop from blocking if lower-priority coroutines are active, thus mapping |
2502 | low-priority coroutines to idle/background tasks). |
3070 | low-priority coroutines to idle/background tasks). |
2503 | |
3071 | |
2504 | It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>) |
3072 | When used for this purpose, it is recommended to give C<ev_check> watchers |
2505 | priority, to ensure that they are being run before any other watchers |
3073 | highest (C<EV_MAXPRI>) priority, to ensure that they are being run before |
2506 | after the poll (this doesn't matter for C<ev_prepare> watchers). |
3074 | any other watchers after the poll (this doesn't matter for C<ev_prepare> |
|
|
3075 | watchers). |
2507 | |
3076 | |
2508 | Also, C<ev_check> watchers (and C<ev_prepare> watchers, too) should not |
3077 | Also, C<ev_check> watchers (and C<ev_prepare> watchers, too) should not |
2509 | activate ("feed") events into libev. While libev fully supports this, they |
3078 | activate ("feed") events into libev. While libev fully supports this, they |
2510 | might get executed before other C<ev_check> watchers did their job. As |
3079 | might get executed before other C<ev_check> watchers did their job. As |
2511 | C<ev_check> watchers are often used to embed other (non-libev) event |
3080 | C<ev_check> watchers are often used to embed other (non-libev) event |
2512 | loops those other event loops might be in an unusable state until their |
3081 | loops those other event loops might be in an unusable state until their |
2513 | C<ev_check> watcher ran (always remind yourself to coexist peacefully with |
3082 | C<ev_check> watcher ran (always remind yourself to coexist peacefully with |
2514 | others). |
3083 | others). |
|
|
3084 | |
|
|
3085 | =head3 Abusing an C<ev_check> watcher for its side-effect |
|
|
3086 | |
|
|
3087 | C<ev_check> (and less often also C<ev_prepare>) watchers can also be |
|
|
3088 | useful because they are called once per event loop iteration. For |
|
|
3089 | example, if you want to handle a large number of connections fairly, you |
|
|
3090 | normally only do a bit of work for each active connection, and if there |
|
|
3091 | is more work to do, you wait for the next event loop iteration, so other |
|
|
3092 | connections have a chance of making progress. |
|
|
3093 | |
|
|
3094 | Using an C<ev_check> watcher is almost enough: it will be called on the |
|
|
3095 | next event loop iteration. However, that isn't as soon as possible - |
|
|
3096 | without external events, your C<ev_check> watcher will not be invoked. |
|
|
3097 | |
|
|
3098 | This is where C<ev_idle> watchers come in handy - all you need is a |
|
|
3099 | single global idle watcher that is active as long as you have one active |
|
|
3100 | C<ev_check> watcher. The C<ev_idle> watcher makes sure the event loop |
|
|
3101 | will not sleep, and the C<ev_check> watcher makes sure a callback gets |
|
|
3102 | invoked. Neither watcher alone can do that. |
2515 | |
3103 | |
2516 | =head3 Watcher-Specific Functions and Data Members |
3104 | =head3 Watcher-Specific Functions and Data Members |
2517 | |
3105 | |
2518 | =over 4 |
3106 | =over 4 |
2519 | |
3107 | |
… | |
… | |
2643 | |
3231 | |
2644 | if (timeout >= 0) |
3232 | if (timeout >= 0) |
2645 | // create/start timer |
3233 | // create/start timer |
2646 | |
3234 | |
2647 | // poll |
3235 | // poll |
2648 | ev_loop (EV_A_ 0); |
3236 | ev_run (EV_A_ 0); |
2649 | |
3237 | |
2650 | // stop timer again |
3238 | // stop timer again |
2651 | if (timeout >= 0) |
3239 | if (timeout >= 0) |
2652 | ev_timer_stop (EV_A_ &to); |
3240 | ev_timer_stop (EV_A_ &to); |
2653 | |
3241 | |
… | |
… | |
2720 | |
3308 | |
2721 | =over 4 |
3309 | =over 4 |
2722 | |
3310 | |
2723 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
3311 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
2724 | |
3312 | |
2725 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
3313 | =item ev_embed_set (ev_embed *, struct ev_loop *embedded_loop) |
2726 | |
3314 | |
2727 | Configures the watcher to embed the given loop, which must be |
3315 | Configures the watcher to embed the given loop, which must be |
2728 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
3316 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
2729 | invoked automatically, otherwise it is the responsibility of the callback |
3317 | invoked automatically, otherwise it is the responsibility of the callback |
2730 | to invoke it (it will continue to be called until the sweep has been done, |
3318 | to invoke it (it will continue to be called until the sweep has been done, |
2731 | if you do not want that, you need to temporarily stop the embed watcher). |
3319 | if you do not want that, you need to temporarily stop the embed watcher). |
2732 | |
3320 | |
2733 | =item ev_embed_sweep (loop, ev_embed *) |
3321 | =item ev_embed_sweep (loop, ev_embed *) |
2734 | |
3322 | |
2735 | Make a single, non-blocking sweep over the embedded loop. This works |
3323 | Make a single, non-blocking sweep over the embedded loop. This works |
2736 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
3324 | similarly to C<ev_run (embedded_loop, EVRUN_NOWAIT)>, but in the most |
2737 | appropriate way for embedded loops. |
3325 | appropriate way for embedded loops. |
2738 | |
3326 | |
2739 | =item struct ev_loop *other [read-only] |
3327 | =item struct ev_loop *other [read-only] |
2740 | |
3328 | |
2741 | The embedded event loop. |
3329 | The embedded event loop. |
… | |
… | |
2751 | used). |
3339 | used). |
2752 | |
3340 | |
2753 | struct ev_loop *loop_hi = ev_default_init (0); |
3341 | struct ev_loop *loop_hi = ev_default_init (0); |
2754 | struct ev_loop *loop_lo = 0; |
3342 | struct ev_loop *loop_lo = 0; |
2755 | ev_embed embed; |
3343 | ev_embed embed; |
2756 | |
3344 | |
2757 | // see if there is a chance of getting one that works |
3345 | // see if there is a chance of getting one that works |
2758 | // (remember that a flags value of 0 means autodetection) |
3346 | // (remember that a flags value of 0 means autodetection) |
2759 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
3347 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
2760 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
3348 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
2761 | : 0; |
3349 | : 0; |
… | |
… | |
2775 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
3363 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
2776 | |
3364 | |
2777 | struct ev_loop *loop = ev_default_init (0); |
3365 | struct ev_loop *loop = ev_default_init (0); |
2778 | struct ev_loop *loop_socket = 0; |
3366 | struct ev_loop *loop_socket = 0; |
2779 | ev_embed embed; |
3367 | ev_embed embed; |
2780 | |
3368 | |
2781 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
3369 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
2782 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
3370 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
2783 | { |
3371 | { |
2784 | ev_embed_init (&embed, 0, loop_socket); |
3372 | ev_embed_init (&embed, 0, loop_socket); |
2785 | ev_embed_start (loop, &embed); |
3373 | ev_embed_start (loop, &embed); |
… | |
… | |
2793 | |
3381 | |
2794 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
3382 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
2795 | |
3383 | |
2796 | Fork watchers are called when a C<fork ()> was detected (usually because |
3384 | Fork watchers are called when a C<fork ()> was detected (usually because |
2797 | whoever is a good citizen cared to tell libev about it by calling |
3385 | whoever is a good citizen cared to tell libev about it by calling |
2798 | C<ev_default_fork> or C<ev_loop_fork>). The invocation is done before the |
3386 | C<ev_loop_fork>). The invocation is done before the event loop blocks next |
2799 | event loop blocks next and before C<ev_check> watchers are being called, |
3387 | and before C<ev_check> watchers are being called, and only in the child |
2800 | and only in the child after the fork. If whoever good citizen calling |
3388 | after the fork. If whoever good citizen calling C<ev_default_fork> cheats |
2801 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
3389 | and calls it in the wrong process, the fork handlers will be invoked, too, |
2802 | handlers will be invoked, too, of course. |
3390 | of course. |
2803 | |
3391 | |
2804 | =head3 The special problem of life after fork - how is it possible? |
3392 | =head3 The special problem of life after fork - how is it possible? |
2805 | |
3393 | |
2806 | Most uses of C<fork()> consist of forking, then some simple calls to ste |
3394 | Most uses of C<fork ()> consist of forking, then some simple calls to set |
2807 | up/change the process environment, followed by a call to C<exec()>. This |
3395 | up/change the process environment, followed by a call to C<exec()>. This |
2808 | sequence should be handled by libev without any problems. |
3396 | sequence should be handled by libev without any problems. |
2809 | |
3397 | |
2810 | This changes when the application actually wants to do event handling |
3398 | This changes when the application actually wants to do event handling |
2811 | in the child, or both parent in child, in effect "continuing" after the |
3399 | in the child, or both parent in child, in effect "continuing" after the |
… | |
… | |
2827 | disadvantage of having to use multiple event loops (which do not support |
3415 | disadvantage of having to use multiple event loops (which do not support |
2828 | signal watchers). |
3416 | signal watchers). |
2829 | |
3417 | |
2830 | When this is not possible, or you want to use the default loop for |
3418 | When this is not possible, or you want to use the default loop for |
2831 | other reasons, then in the process that wants to start "fresh", call |
3419 | other reasons, then in the process that wants to start "fresh", call |
2832 | C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying |
3420 | C<ev_loop_destroy (EV_DEFAULT)> followed by C<ev_default_loop (...)>. |
2833 | the default loop will "orphan" (not stop) all registered watchers, so you |
3421 | Destroying the default loop will "orphan" (not stop) all registered |
2834 | have to be careful not to execute code that modifies those watchers. Note |
3422 | watchers, so you have to be careful not to execute code that modifies |
2835 | also that in that case, you have to re-register any signal watchers. |
3423 | those watchers. Note also that in that case, you have to re-register any |
|
|
3424 | signal watchers. |
2836 | |
3425 | |
2837 | =head3 Watcher-Specific Functions and Data Members |
3426 | =head3 Watcher-Specific Functions and Data Members |
2838 | |
3427 | |
2839 | =over 4 |
3428 | =over 4 |
2840 | |
3429 | |
2841 | =item ev_fork_init (ev_signal *, callback) |
3430 | =item ev_fork_init (ev_fork *, callback) |
2842 | |
3431 | |
2843 | Initialises and configures the fork watcher - it has no parameters of any |
3432 | Initialises and configures the fork watcher - it has no parameters of any |
2844 | kind. There is a C<ev_fork_set> macro, but using it is utterly pointless, |
3433 | kind. There is a C<ev_fork_set> macro, but using it is utterly pointless, |
2845 | believe me. |
3434 | really. |
2846 | |
3435 | |
2847 | =back |
3436 | =back |
2848 | |
3437 | |
2849 | |
3438 | |
|
|
3439 | =head2 C<ev_cleanup> - even the best things end |
|
|
3440 | |
|
|
3441 | Cleanup watchers are called just before the event loop is being destroyed |
|
|
3442 | by a call to C<ev_loop_destroy>. |
|
|
3443 | |
|
|
3444 | While there is no guarantee that the event loop gets destroyed, cleanup |
|
|
3445 | watchers provide a convenient method to install cleanup hooks for your |
|
|
3446 | program, worker threads and so on - you just to make sure to destroy the |
|
|
3447 | loop when you want them to be invoked. |
|
|
3448 | |
|
|
3449 | Cleanup watchers are invoked in the same way as any other watcher. Unlike |
|
|
3450 | all other watchers, they do not keep a reference to the event loop (which |
|
|
3451 | makes a lot of sense if you think about it). Like all other watchers, you |
|
|
3452 | can call libev functions in the callback, except C<ev_cleanup_start>. |
|
|
3453 | |
|
|
3454 | =head3 Watcher-Specific Functions and Data Members |
|
|
3455 | |
|
|
3456 | =over 4 |
|
|
3457 | |
|
|
3458 | =item ev_cleanup_init (ev_cleanup *, callback) |
|
|
3459 | |
|
|
3460 | Initialises and configures the cleanup watcher - it has no parameters of |
|
|
3461 | any kind. There is a C<ev_cleanup_set> macro, but using it is utterly |
|
|
3462 | pointless, I assure you. |
|
|
3463 | |
|
|
3464 | =back |
|
|
3465 | |
|
|
3466 | Example: Register an atexit handler to destroy the default loop, so any |
|
|
3467 | cleanup functions are called. |
|
|
3468 | |
|
|
3469 | static void |
|
|
3470 | program_exits (void) |
|
|
3471 | { |
|
|
3472 | ev_loop_destroy (EV_DEFAULT_UC); |
|
|
3473 | } |
|
|
3474 | |
|
|
3475 | ... |
|
|
3476 | atexit (program_exits); |
|
|
3477 | |
|
|
3478 | |
2850 | =head2 C<ev_async> - how to wake up another event loop |
3479 | =head2 C<ev_async> - how to wake up an event loop |
2851 | |
3480 | |
2852 | In general, you cannot use an C<ev_loop> from multiple threads or other |
3481 | In general, you cannot use an C<ev_loop> from multiple threads or other |
2853 | asynchronous sources such as signal handlers (as opposed to multiple event |
3482 | asynchronous sources such as signal handlers (as opposed to multiple event |
2854 | loops - those are of course safe to use in different threads). |
3483 | loops - those are of course safe to use in different threads). |
2855 | |
3484 | |
2856 | Sometimes, however, you need to wake up another event loop you do not |
3485 | Sometimes, however, you need to wake up an event loop you do not control, |
2857 | control, for example because it belongs to another thread. This is what |
3486 | for example because it belongs to another thread. This is what C<ev_async> |
2858 | C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you |
3487 | watchers do: as long as the C<ev_async> watcher is active, you can signal |
2859 | can signal it by calling C<ev_async_send>, which is thread- and signal |
3488 | it by calling C<ev_async_send>, which is thread- and signal safe. |
2860 | safe. |
|
|
2861 | |
3489 | |
2862 | This functionality is very similar to C<ev_signal> watchers, as signals, |
3490 | This functionality is very similar to C<ev_signal> watchers, as signals, |
2863 | too, are asynchronous in nature, and signals, too, will be compressed |
3491 | too, are asynchronous in nature, and signals, too, will be compressed |
2864 | (i.e. the number of callback invocations may be less than the number of |
3492 | (i.e. the number of callback invocations may be less than the number of |
2865 | C<ev_async_sent> calls). |
3493 | C<ev_async_send> calls). In fact, you could use signal watchers as a kind |
2866 | |
3494 | of "global async watchers" by using a watcher on an otherwise unused |
2867 | Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not |
3495 | signal, and C<ev_feed_signal> to signal this watcher from another thread, |
2868 | just the default loop. |
3496 | even without knowing which loop owns the signal. |
2869 | |
3497 | |
2870 | =head3 Queueing |
3498 | =head3 Queueing |
2871 | |
3499 | |
2872 | C<ev_async> does not support queueing of data in any way. The reason |
3500 | C<ev_async> does not support queueing of data in any way. The reason |
2873 | is that the author does not know of a simple (or any) algorithm for a |
3501 | is that the author does not know of a simple (or any) algorithm for a |
2874 | multiple-writer-single-reader queue that works in all cases and doesn't |
3502 | multiple-writer-single-reader queue that works in all cases and doesn't |
2875 | need elaborate support such as pthreads. |
3503 | need elaborate support such as pthreads or unportable memory access |
|
|
3504 | semantics. |
2876 | |
3505 | |
2877 | That means that if you want to queue data, you have to provide your own |
3506 | That means that if you want to queue data, you have to provide your own |
2878 | queue. But at least I can tell you how to implement locking around your |
3507 | queue. But at least I can tell you how to implement locking around your |
2879 | queue: |
3508 | queue: |
2880 | |
3509 | |
… | |
… | |
2964 | trust me. |
3593 | trust me. |
2965 | |
3594 | |
2966 | =item ev_async_send (loop, ev_async *) |
3595 | =item ev_async_send (loop, ev_async *) |
2967 | |
3596 | |
2968 | Sends/signals/activates the given C<ev_async> watcher, that is, feeds |
3597 | Sends/signals/activates the given C<ev_async> watcher, that is, feeds |
2969 | an C<EV_ASYNC> event on the watcher into the event loop. Unlike |
3598 | an C<EV_ASYNC> event on the watcher into the event loop, and instantly |
|
|
3599 | returns. |
|
|
3600 | |
2970 | C<ev_feed_event>, this call is safe to do from other threads, signal or |
3601 | Unlike C<ev_feed_event>, this call is safe to do from other threads, |
2971 | similar contexts (see the discussion of C<EV_ATOMIC_T> in the embedding |
3602 | signal or similar contexts (see the discussion of C<EV_ATOMIC_T> in the |
2972 | section below on what exactly this means). |
3603 | embedding section below on what exactly this means). |
2973 | |
3604 | |
2974 | Note that, as with other watchers in libev, multiple events might get |
3605 | Note that, as with other watchers in libev, multiple events might get |
2975 | compressed into a single callback invocation (another way to look at this |
3606 | compressed into a single callback invocation (another way to look at |
2976 | is that C<ev_async> watchers are level-triggered, set on C<ev_async_send>, |
3607 | this is that C<ev_async> watchers are level-triggered: they are set on |
2977 | reset when the event loop detects that). |
3608 | C<ev_async_send>, reset when the event loop detects that). |
2978 | |
3609 | |
2979 | This call incurs the overhead of a system call only once per event loop |
3610 | This call incurs the overhead of at most one extra system call per event |
2980 | iteration, so while the overhead might be noticeable, it doesn't apply to |
3611 | loop iteration, if the event loop is blocked, and no syscall at all if |
2981 | repeated calls to C<ev_async_send> for the same event loop. |
3612 | the event loop (or your program) is processing events. That means that |
|
|
3613 | repeated calls are basically free (there is no need to avoid calls for |
|
|
3614 | performance reasons) and that the overhead becomes smaller (typically |
|
|
3615 | zero) under load. |
2982 | |
3616 | |
2983 | =item bool = ev_async_pending (ev_async *) |
3617 | =item bool = ev_async_pending (ev_async *) |
2984 | |
3618 | |
2985 | Returns a non-zero value when C<ev_async_send> has been called on the |
3619 | Returns a non-zero value when C<ev_async_send> has been called on the |
2986 | watcher but the event has not yet been processed (or even noted) by the |
3620 | watcher but the event has not yet been processed (or even noted) by the |
… | |
… | |
3003 | |
3637 | |
3004 | There are some other functions of possible interest. Described. Here. Now. |
3638 | There are some other functions of possible interest. Described. Here. Now. |
3005 | |
3639 | |
3006 | =over 4 |
3640 | =over 4 |
3007 | |
3641 | |
3008 | =item ev_once (loop, int fd, int events, ev_tstamp timeout, callback) |
3642 | =item ev_once (loop, int fd, int events, ev_tstamp timeout, callback, arg) |
3009 | |
3643 | |
3010 | This function combines a simple timer and an I/O watcher, calls your |
3644 | This function combines a simple timer and an I/O watcher, calls your |
3011 | callback on whichever event happens first and automatically stops both |
3645 | callback on whichever event happens first and automatically stops both |
3012 | watchers. This is useful if you want to wait for a single event on an fd |
3646 | watchers. This is useful if you want to wait for a single event on an fd |
3013 | or timeout without having to allocate/configure/start/stop/free one or |
3647 | or timeout without having to allocate/configure/start/stop/free one or |
… | |
… | |
3019 | |
3653 | |
3020 | If C<timeout> is less than 0, then no timeout watcher will be |
3654 | If C<timeout> is less than 0, then no timeout watcher will be |
3021 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
3655 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
3022 | repeat = 0) will be started. C<0> is a valid timeout. |
3656 | repeat = 0) will be started. C<0> is a valid timeout. |
3023 | |
3657 | |
3024 | The callback has the type C<void (*cb)(int revents, void *arg)> and gets |
3658 | The callback has the type C<void (*cb)(int revents, void *arg)> and is |
3025 | passed an C<revents> set like normal event callbacks (a combination of |
3659 | passed an C<revents> set like normal event callbacks (a combination of |
3026 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg> |
3660 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMER>) and the C<arg> |
3027 | value passed to C<ev_once>. Note that it is possible to receive I<both> |
3661 | value passed to C<ev_once>. Note that it is possible to receive I<both> |
3028 | a timeout and an io event at the same time - you probably should give io |
3662 | a timeout and an io event at the same time - you probably should give io |
3029 | events precedence. |
3663 | events precedence. |
3030 | |
3664 | |
3031 | Example: wait up to ten seconds for data to appear on STDIN_FILENO. |
3665 | Example: wait up to ten seconds for data to appear on STDIN_FILENO. |
3032 | |
3666 | |
3033 | static void stdin_ready (int revents, void *arg) |
3667 | static void stdin_ready (int revents, void *arg) |
3034 | { |
3668 | { |
3035 | if (revents & EV_READ) |
3669 | if (revents & EV_READ) |
3036 | /* stdin might have data for us, joy! */; |
3670 | /* stdin might have data for us, joy! */; |
3037 | else if (revents & EV_TIMEOUT) |
3671 | else if (revents & EV_TIMER) |
3038 | /* doh, nothing entered */; |
3672 | /* doh, nothing entered */; |
3039 | } |
3673 | } |
3040 | |
3674 | |
3041 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3675 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3042 | |
3676 | |
3043 | =item ev_feed_event (struct ev_loop *, watcher *, int revents) |
|
|
3044 | |
|
|
3045 | Feeds the given event set into the event loop, as if the specified event |
|
|
3046 | had happened for the specified watcher (which must be a pointer to an |
|
|
3047 | initialised but not necessarily started event watcher). |
|
|
3048 | |
|
|
3049 | =item ev_feed_fd_event (struct ev_loop *, int fd, int revents) |
3677 | =item ev_feed_fd_event (loop, int fd, int revents) |
3050 | |
3678 | |
3051 | Feed an event on the given fd, as if a file descriptor backend detected |
3679 | Feed an event on the given fd, as if a file descriptor backend detected |
3052 | the given events it. |
3680 | the given events. |
3053 | |
3681 | |
3054 | =item ev_feed_signal_event (struct ev_loop *loop, int signum) |
3682 | =item ev_feed_signal_event (loop, int signum) |
3055 | |
3683 | |
3056 | Feed an event as if the given signal occurred (C<loop> must be the default |
3684 | Feed an event as if the given signal occurred. See also C<ev_feed_signal>, |
3057 | loop!). |
3685 | which is async-safe. |
3058 | |
3686 | |
3059 | =back |
3687 | =back |
|
|
3688 | |
|
|
3689 | |
|
|
3690 | =head1 COMMON OR USEFUL IDIOMS (OR BOTH) |
|
|
3691 | |
|
|
3692 | This section explains some common idioms that are not immediately |
|
|
3693 | obvious. Note that examples are sprinkled over the whole manual, and this |
|
|
3694 | section only contains stuff that wouldn't fit anywhere else. |
|
|
3695 | |
|
|
3696 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
|
|
3697 | |
|
|
3698 | Each watcher has, by default, a C<void *data> member that you can read |
|
|
3699 | or modify at any time: libev will completely ignore it. This can be used |
|
|
3700 | to associate arbitrary data with your watcher. If you need more data and |
|
|
3701 | don't want to allocate memory separately and store a pointer to it in that |
|
|
3702 | data member, you can also "subclass" the watcher type and provide your own |
|
|
3703 | data: |
|
|
3704 | |
|
|
3705 | struct my_io |
|
|
3706 | { |
|
|
3707 | ev_io io; |
|
|
3708 | int otherfd; |
|
|
3709 | void *somedata; |
|
|
3710 | struct whatever *mostinteresting; |
|
|
3711 | }; |
|
|
3712 | |
|
|
3713 | ... |
|
|
3714 | struct my_io w; |
|
|
3715 | ev_io_init (&w.io, my_cb, fd, EV_READ); |
|
|
3716 | |
|
|
3717 | And since your callback will be called with a pointer to the watcher, you |
|
|
3718 | can cast it back to your own type: |
|
|
3719 | |
|
|
3720 | static void my_cb (struct ev_loop *loop, ev_io *w_, int revents) |
|
|
3721 | { |
|
|
3722 | struct my_io *w = (struct my_io *)w_; |
|
|
3723 | ... |
|
|
3724 | } |
|
|
3725 | |
|
|
3726 | More interesting and less C-conformant ways of casting your callback |
|
|
3727 | function type instead have been omitted. |
|
|
3728 | |
|
|
3729 | =head2 BUILDING YOUR OWN COMPOSITE WATCHERS |
|
|
3730 | |
|
|
3731 | Another common scenario is to use some data structure with multiple |
|
|
3732 | embedded watchers, in effect creating your own watcher that combines |
|
|
3733 | multiple libev event sources into one "super-watcher": |
|
|
3734 | |
|
|
3735 | struct my_biggy |
|
|
3736 | { |
|
|
3737 | int some_data; |
|
|
3738 | ev_timer t1; |
|
|
3739 | ev_timer t2; |
|
|
3740 | } |
|
|
3741 | |
|
|
3742 | In this case getting the pointer to C<my_biggy> is a bit more |
|
|
3743 | complicated: Either you store the address of your C<my_biggy> struct in |
|
|
3744 | the C<data> member of the watcher (for woozies or C++ coders), or you need |
|
|
3745 | to use some pointer arithmetic using C<offsetof> inside your watchers (for |
|
|
3746 | real programmers): |
|
|
3747 | |
|
|
3748 | #include <stddef.h> |
|
|
3749 | |
|
|
3750 | static void |
|
|
3751 | t1_cb (EV_P_ ev_timer *w, int revents) |
|
|
3752 | { |
|
|
3753 | struct my_biggy big = (struct my_biggy *) |
|
|
3754 | (((char *)w) - offsetof (struct my_biggy, t1)); |
|
|
3755 | } |
|
|
3756 | |
|
|
3757 | static void |
|
|
3758 | t2_cb (EV_P_ ev_timer *w, int revents) |
|
|
3759 | { |
|
|
3760 | struct my_biggy big = (struct my_biggy *) |
|
|
3761 | (((char *)w) - offsetof (struct my_biggy, t2)); |
|
|
3762 | } |
|
|
3763 | |
|
|
3764 | =head2 AVOIDING FINISHING BEFORE RETURNING |
|
|
3765 | |
|
|
3766 | Often you have structures like this in event-based programs: |
|
|
3767 | |
|
|
3768 | callback () |
|
|
3769 | { |
|
|
3770 | free (request); |
|
|
3771 | } |
|
|
3772 | |
|
|
3773 | request = start_new_request (..., callback); |
|
|
3774 | |
|
|
3775 | The intent is to start some "lengthy" operation. The C<request> could be |
|
|
3776 | used to cancel the operation, or do other things with it. |
|
|
3777 | |
|
|
3778 | It's not uncommon to have code paths in C<start_new_request> that |
|
|
3779 | immediately invoke the callback, for example, to report errors. Or you add |
|
|
3780 | some caching layer that finds that it can skip the lengthy aspects of the |
|
|
3781 | operation and simply invoke the callback with the result. |
|
|
3782 | |
|
|
3783 | The problem here is that this will happen I<before> C<start_new_request> |
|
|
3784 | has returned, so C<request> is not set. |
|
|
3785 | |
|
|
3786 | Even if you pass the request by some safer means to the callback, you |
|
|
3787 | might want to do something to the request after starting it, such as |
|
|
3788 | canceling it, which probably isn't working so well when the callback has |
|
|
3789 | already been invoked. |
|
|
3790 | |
|
|
3791 | A common way around all these issues is to make sure that |
|
|
3792 | C<start_new_request> I<always> returns before the callback is invoked. If |
|
|
3793 | C<start_new_request> immediately knows the result, it can artificially |
|
|
3794 | delay invoking the callback by using a C<prepare> or C<idle> watcher for |
|
|
3795 | example, or more sneakily, by reusing an existing (stopped) watcher and |
|
|
3796 | pushing it into the pending queue: |
|
|
3797 | |
|
|
3798 | ev_set_cb (watcher, callback); |
|
|
3799 | ev_feed_event (EV_A_ watcher, 0); |
|
|
3800 | |
|
|
3801 | This way, C<start_new_request> can safely return before the callback is |
|
|
3802 | invoked, while not delaying callback invocation too much. |
|
|
3803 | |
|
|
3804 | =head2 MODEL/NESTED EVENT LOOP INVOCATIONS AND EXIT CONDITIONS |
|
|
3805 | |
|
|
3806 | Often (especially in GUI toolkits) there are places where you have |
|
|
3807 | I<modal> interaction, which is most easily implemented by recursively |
|
|
3808 | invoking C<ev_run>. |
|
|
3809 | |
|
|
3810 | This brings the problem of exiting - a callback might want to finish the |
|
|
3811 | main C<ev_run> call, but not the nested one (e.g. user clicked "Quit", but |
|
|
3812 | a modal "Are you sure?" dialog is still waiting), or just the nested one |
|
|
3813 | and not the main one (e.g. user clocked "Ok" in a modal dialog), or some |
|
|
3814 | other combination: In these cases, a simple C<ev_break> will not work. |
|
|
3815 | |
|
|
3816 | The solution is to maintain "break this loop" variable for each C<ev_run> |
|
|
3817 | invocation, and use a loop around C<ev_run> until the condition is |
|
|
3818 | triggered, using C<EVRUN_ONCE>: |
|
|
3819 | |
|
|
3820 | // main loop |
|
|
3821 | int exit_main_loop = 0; |
|
|
3822 | |
|
|
3823 | while (!exit_main_loop) |
|
|
3824 | ev_run (EV_DEFAULT_ EVRUN_ONCE); |
|
|
3825 | |
|
|
3826 | // in a modal watcher |
|
|
3827 | int exit_nested_loop = 0; |
|
|
3828 | |
|
|
3829 | while (!exit_nested_loop) |
|
|
3830 | ev_run (EV_A_ EVRUN_ONCE); |
|
|
3831 | |
|
|
3832 | To exit from any of these loops, just set the corresponding exit variable: |
|
|
3833 | |
|
|
3834 | // exit modal loop |
|
|
3835 | exit_nested_loop = 1; |
|
|
3836 | |
|
|
3837 | // exit main program, after modal loop is finished |
|
|
3838 | exit_main_loop = 1; |
|
|
3839 | |
|
|
3840 | // exit both |
|
|
3841 | exit_main_loop = exit_nested_loop = 1; |
|
|
3842 | |
|
|
3843 | =head2 THREAD LOCKING EXAMPLE |
|
|
3844 | |
|
|
3845 | Here is a fictitious example of how to run an event loop in a different |
|
|
3846 | thread from where callbacks are being invoked and watchers are |
|
|
3847 | created/added/removed. |
|
|
3848 | |
|
|
3849 | For a real-world example, see the C<EV::Loop::Async> perl module, |
|
|
3850 | which uses exactly this technique (which is suited for many high-level |
|
|
3851 | languages). |
|
|
3852 | |
|
|
3853 | The example uses a pthread mutex to protect the loop data, a condition |
|
|
3854 | variable to wait for callback invocations, an async watcher to notify the |
|
|
3855 | event loop thread and an unspecified mechanism to wake up the main thread. |
|
|
3856 | |
|
|
3857 | First, you need to associate some data with the event loop: |
|
|
3858 | |
|
|
3859 | typedef struct { |
|
|
3860 | mutex_t lock; /* global loop lock */ |
|
|
3861 | ev_async async_w; |
|
|
3862 | thread_t tid; |
|
|
3863 | cond_t invoke_cv; |
|
|
3864 | } userdata; |
|
|
3865 | |
|
|
3866 | void prepare_loop (EV_P) |
|
|
3867 | { |
|
|
3868 | // for simplicity, we use a static userdata struct. |
|
|
3869 | static userdata u; |
|
|
3870 | |
|
|
3871 | ev_async_init (&u->async_w, async_cb); |
|
|
3872 | ev_async_start (EV_A_ &u->async_w); |
|
|
3873 | |
|
|
3874 | pthread_mutex_init (&u->lock, 0); |
|
|
3875 | pthread_cond_init (&u->invoke_cv, 0); |
|
|
3876 | |
|
|
3877 | // now associate this with the loop |
|
|
3878 | ev_set_userdata (EV_A_ u); |
|
|
3879 | ev_set_invoke_pending_cb (EV_A_ l_invoke); |
|
|
3880 | ev_set_loop_release_cb (EV_A_ l_release, l_acquire); |
|
|
3881 | |
|
|
3882 | // then create the thread running ev_run |
|
|
3883 | pthread_create (&u->tid, 0, l_run, EV_A); |
|
|
3884 | } |
|
|
3885 | |
|
|
3886 | The callback for the C<ev_async> watcher does nothing: the watcher is used |
|
|
3887 | solely to wake up the event loop so it takes notice of any new watchers |
|
|
3888 | that might have been added: |
|
|
3889 | |
|
|
3890 | static void |
|
|
3891 | async_cb (EV_P_ ev_async *w, int revents) |
|
|
3892 | { |
|
|
3893 | // just used for the side effects |
|
|
3894 | } |
|
|
3895 | |
|
|
3896 | The C<l_release> and C<l_acquire> callbacks simply unlock/lock the mutex |
|
|
3897 | protecting the loop data, respectively. |
|
|
3898 | |
|
|
3899 | static void |
|
|
3900 | l_release (EV_P) |
|
|
3901 | { |
|
|
3902 | userdata *u = ev_userdata (EV_A); |
|
|
3903 | pthread_mutex_unlock (&u->lock); |
|
|
3904 | } |
|
|
3905 | |
|
|
3906 | static void |
|
|
3907 | l_acquire (EV_P) |
|
|
3908 | { |
|
|
3909 | userdata *u = ev_userdata (EV_A); |
|
|
3910 | pthread_mutex_lock (&u->lock); |
|
|
3911 | } |
|
|
3912 | |
|
|
3913 | The event loop thread first acquires the mutex, and then jumps straight |
|
|
3914 | into C<ev_run>: |
|
|
3915 | |
|
|
3916 | void * |
|
|
3917 | l_run (void *thr_arg) |
|
|
3918 | { |
|
|
3919 | struct ev_loop *loop = (struct ev_loop *)thr_arg; |
|
|
3920 | |
|
|
3921 | l_acquire (EV_A); |
|
|
3922 | pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
|
|
3923 | ev_run (EV_A_ 0); |
|
|
3924 | l_release (EV_A); |
|
|
3925 | |
|
|
3926 | return 0; |
|
|
3927 | } |
|
|
3928 | |
|
|
3929 | Instead of invoking all pending watchers, the C<l_invoke> callback will |
|
|
3930 | signal the main thread via some unspecified mechanism (signals? pipe |
|
|
3931 | writes? C<Async::Interrupt>?) and then waits until all pending watchers |
|
|
3932 | have been called (in a while loop because a) spurious wakeups are possible |
|
|
3933 | and b) skipping inter-thread-communication when there are no pending |
|
|
3934 | watchers is very beneficial): |
|
|
3935 | |
|
|
3936 | static void |
|
|
3937 | l_invoke (EV_P) |
|
|
3938 | { |
|
|
3939 | userdata *u = ev_userdata (EV_A); |
|
|
3940 | |
|
|
3941 | while (ev_pending_count (EV_A)) |
|
|
3942 | { |
|
|
3943 | wake_up_other_thread_in_some_magic_or_not_so_magic_way (); |
|
|
3944 | pthread_cond_wait (&u->invoke_cv, &u->lock); |
|
|
3945 | } |
|
|
3946 | } |
|
|
3947 | |
|
|
3948 | Now, whenever the main thread gets told to invoke pending watchers, it |
|
|
3949 | will grab the lock, call C<ev_invoke_pending> and then signal the loop |
|
|
3950 | thread to continue: |
|
|
3951 | |
|
|
3952 | static void |
|
|
3953 | real_invoke_pending (EV_P) |
|
|
3954 | { |
|
|
3955 | userdata *u = ev_userdata (EV_A); |
|
|
3956 | |
|
|
3957 | pthread_mutex_lock (&u->lock); |
|
|
3958 | ev_invoke_pending (EV_A); |
|
|
3959 | pthread_cond_signal (&u->invoke_cv); |
|
|
3960 | pthread_mutex_unlock (&u->lock); |
|
|
3961 | } |
|
|
3962 | |
|
|
3963 | Whenever you want to start/stop a watcher or do other modifications to an |
|
|
3964 | event loop, you will now have to lock: |
|
|
3965 | |
|
|
3966 | ev_timer timeout_watcher; |
|
|
3967 | userdata *u = ev_userdata (EV_A); |
|
|
3968 | |
|
|
3969 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
|
|
3970 | |
|
|
3971 | pthread_mutex_lock (&u->lock); |
|
|
3972 | ev_timer_start (EV_A_ &timeout_watcher); |
|
|
3973 | ev_async_send (EV_A_ &u->async_w); |
|
|
3974 | pthread_mutex_unlock (&u->lock); |
|
|
3975 | |
|
|
3976 | Note that sending the C<ev_async> watcher is required because otherwise |
|
|
3977 | an event loop currently blocking in the kernel will have no knowledge |
|
|
3978 | about the newly added timer. By waking up the loop it will pick up any new |
|
|
3979 | watchers in the next event loop iteration. |
|
|
3980 | |
|
|
3981 | =head2 THREADS, COROUTINES, CONTINUATIONS, QUEUES... INSTEAD OF CALLBACKS |
|
|
3982 | |
|
|
3983 | While the overhead of a callback that e.g. schedules a thread is small, it |
|
|
3984 | is still an overhead. If you embed libev, and your main usage is with some |
|
|
3985 | kind of threads or coroutines, you might want to customise libev so that |
|
|
3986 | doesn't need callbacks anymore. |
|
|
3987 | |
|
|
3988 | Imagine you have coroutines that you can switch to using a function |
|
|
3989 | C<switch_to (coro)>, that libev runs in a coroutine called C<libev_coro> |
|
|
3990 | and that due to some magic, the currently active coroutine is stored in a |
|
|
3991 | global called C<current_coro>. Then you can build your own "wait for libev |
|
|
3992 | event" primitive by changing C<EV_CB_DECLARE> and C<EV_CB_INVOKE> (note |
|
|
3993 | the differing C<;> conventions): |
|
|
3994 | |
|
|
3995 | #define EV_CB_DECLARE(type) struct my_coro *cb; |
|
|
3996 | #define EV_CB_INVOKE(watcher) switch_to ((watcher)->cb) |
|
|
3997 | |
|
|
3998 | That means instead of having a C callback function, you store the |
|
|
3999 | coroutine to switch to in each watcher, and instead of having libev call |
|
|
4000 | your callback, you instead have it switch to that coroutine. |
|
|
4001 | |
|
|
4002 | A coroutine might now wait for an event with a function called |
|
|
4003 | C<wait_for_event>. (the watcher needs to be started, as always, but it doesn't |
|
|
4004 | matter when, or whether the watcher is active or not when this function is |
|
|
4005 | called): |
|
|
4006 | |
|
|
4007 | void |
|
|
4008 | wait_for_event (ev_watcher *w) |
|
|
4009 | { |
|
|
4010 | ev_set_cb (w, current_coro); |
|
|
4011 | switch_to (libev_coro); |
|
|
4012 | } |
|
|
4013 | |
|
|
4014 | That basically suspends the coroutine inside C<wait_for_event> and |
|
|
4015 | continues the libev coroutine, which, when appropriate, switches back to |
|
|
4016 | this or any other coroutine. |
|
|
4017 | |
|
|
4018 | You can do similar tricks if you have, say, threads with an event queue - |
|
|
4019 | instead of storing a coroutine, you store the queue object and instead of |
|
|
4020 | switching to a coroutine, you push the watcher onto the queue and notify |
|
|
4021 | any waiters. |
|
|
4022 | |
|
|
4023 | To embed libev, see L</EMBEDDING>, but in short, it's easiest to create two |
|
|
4024 | files, F<my_ev.h> and F<my_ev.c> that include the respective libev files: |
|
|
4025 | |
|
|
4026 | // my_ev.h |
|
|
4027 | #define EV_CB_DECLARE(type) struct my_coro *cb; |
|
|
4028 | #define EV_CB_INVOKE(watcher) switch_to ((watcher)->cb) |
|
|
4029 | #include "../libev/ev.h" |
|
|
4030 | |
|
|
4031 | // my_ev.c |
|
|
4032 | #define EV_H "my_ev.h" |
|
|
4033 | #include "../libev/ev.c" |
|
|
4034 | |
|
|
4035 | And then use F<my_ev.h> when you would normally use F<ev.h>, and compile |
|
|
4036 | F<my_ev.c> into your project. When properly specifying include paths, you |
|
|
4037 | can even use F<ev.h> as header file name directly. |
3060 | |
4038 | |
3061 | |
4039 | |
3062 | =head1 LIBEVENT EMULATION |
4040 | =head1 LIBEVENT EMULATION |
3063 | |
4041 | |
3064 | Libev offers a compatibility emulation layer for libevent. It cannot |
4042 | Libev offers a compatibility emulation layer for libevent. It cannot |
3065 | emulate the internals of libevent, so here are some usage hints: |
4043 | emulate the internals of libevent, so here are some usage hints: |
3066 | |
4044 | |
3067 | =over 4 |
4045 | =over 4 |
|
|
4046 | |
|
|
4047 | =item * Only the libevent-1.4.1-beta API is being emulated. |
|
|
4048 | |
|
|
4049 | This was the newest libevent version available when libev was implemented, |
|
|
4050 | and is still mostly unchanged in 2010. |
3068 | |
4051 | |
3069 | =item * Use it by including <event.h>, as usual. |
4052 | =item * Use it by including <event.h>, as usual. |
3070 | |
4053 | |
3071 | =item * The following members are fully supported: ev_base, ev_callback, |
4054 | =item * The following members are fully supported: ev_base, ev_callback, |
3072 | ev_arg, ev_fd, ev_res, ev_events. |
4055 | ev_arg, ev_fd, ev_res, ev_events. |
… | |
… | |
3078 | =item * Priorities are not currently supported. Initialising priorities |
4061 | =item * Priorities are not currently supported. Initialising priorities |
3079 | will fail and all watchers will have the same priority, even though there |
4062 | will fail and all watchers will have the same priority, even though there |
3080 | is an ev_pri field. |
4063 | is an ev_pri field. |
3081 | |
4064 | |
3082 | =item * In libevent, the last base created gets the signals, in libev, the |
4065 | =item * In libevent, the last base created gets the signals, in libev, the |
3083 | first base created (== the default loop) gets the signals. |
4066 | base that registered the signal gets the signals. |
3084 | |
4067 | |
3085 | =item * Other members are not supported. |
4068 | =item * Other members are not supported. |
3086 | |
4069 | |
3087 | =item * The libev emulation is I<not> ABI compatible to libevent, you need |
4070 | =item * The libev emulation is I<not> ABI compatible to libevent, you need |
3088 | to use the libev header file and library. |
4071 | to use the libev header file and library. |
3089 | |
4072 | |
3090 | =back |
4073 | =back |
3091 | |
4074 | |
3092 | =head1 C++ SUPPORT |
4075 | =head1 C++ SUPPORT |
|
|
4076 | |
|
|
4077 | =head2 C API |
|
|
4078 | |
|
|
4079 | The normal C API should work fine when used from C++: both ev.h and the |
|
|
4080 | libev sources can be compiled as C++. Therefore, code that uses the C API |
|
|
4081 | will work fine. |
|
|
4082 | |
|
|
4083 | Proper exception specifications might have to be added to callbacks passed |
|
|
4084 | to libev: exceptions may be thrown only from watcher callbacks, all other |
|
|
4085 | callbacks (allocator, syserr, loop acquire/release and periodic reschedule |
|
|
4086 | callbacks) must not throw exceptions, and might need a C<noexcept> |
|
|
4087 | specification. If you have code that needs to be compiled as both C and |
|
|
4088 | C++ you can use the C<EV_NOEXCEPT> macro for this: |
|
|
4089 | |
|
|
4090 | static void |
|
|
4091 | fatal_error (const char *msg) EV_NOEXCEPT |
|
|
4092 | { |
|
|
4093 | perror (msg); |
|
|
4094 | abort (); |
|
|
4095 | } |
|
|
4096 | |
|
|
4097 | ... |
|
|
4098 | ev_set_syserr_cb (fatal_error); |
|
|
4099 | |
|
|
4100 | The only API functions that can currently throw exceptions are C<ev_run>, |
|
|
4101 | C<ev_invoke>, C<ev_invoke_pending> and C<ev_loop_destroy> (the latter |
|
|
4102 | because it runs cleanup watchers). |
|
|
4103 | |
|
|
4104 | Throwing exceptions in watcher callbacks is only supported if libev itself |
|
|
4105 | is compiled with a C++ compiler or your C and C++ environments allow |
|
|
4106 | throwing exceptions through C libraries (most do). |
|
|
4107 | |
|
|
4108 | =head2 C++ API |
3093 | |
4109 | |
3094 | Libev comes with some simplistic wrapper classes for C++ that mainly allow |
4110 | Libev comes with some simplistic wrapper classes for C++ that mainly allow |
3095 | you to use some convenience methods to start/stop watchers and also change |
4111 | you to use some convenience methods to start/stop watchers and also change |
3096 | the callback model to a model using method callbacks on objects. |
4112 | the callback model to a model using method callbacks on objects. |
3097 | |
4113 | |
3098 | To use it, |
4114 | To use it, |
3099 | |
4115 | |
3100 | #include <ev++.h> |
4116 | #include <ev++.h> |
3101 | |
4117 | |
3102 | This automatically includes F<ev.h> and puts all of its definitions (many |
4118 | This automatically includes F<ev.h> and puts all of its definitions (many |
3103 | of them macros) into the global namespace. All C++ specific things are |
4119 | of them macros) into the global namespace. All C++ specific things are |
3104 | put into the C<ev> namespace. It should support all the same embedding |
4120 | put into the C<ev> namespace. It should support all the same embedding |
… | |
… | |
3107 | Care has been taken to keep the overhead low. The only data member the C++ |
4123 | Care has been taken to keep the overhead low. The only data member the C++ |
3108 | classes add (compared to plain C-style watchers) is the event loop pointer |
4124 | classes add (compared to plain C-style watchers) is the event loop pointer |
3109 | that the watcher is associated with (or no additional members at all if |
4125 | that the watcher is associated with (or no additional members at all if |
3110 | you disable C<EV_MULTIPLICITY> when embedding libev). |
4126 | you disable C<EV_MULTIPLICITY> when embedding libev). |
3111 | |
4127 | |
3112 | Currently, functions, and static and non-static member functions can be |
4128 | Currently, functions, static and non-static member functions and classes |
3113 | used as callbacks. Other types should be easy to add as long as they only |
4129 | with C<operator ()> can be used as callbacks. Other types should be easy |
3114 | need one additional pointer for context. If you need support for other |
4130 | to add as long as they only need one additional pointer for context. If |
3115 | types of functors please contact the author (preferably after implementing |
4131 | you need support for other types of functors please contact the author |
3116 | it). |
4132 | (preferably after implementing it). |
|
|
4133 | |
|
|
4134 | For all this to work, your C++ compiler either has to use the same calling |
|
|
4135 | conventions as your C compiler (for static member functions), or you have |
|
|
4136 | to embed libev and compile libev itself as C++. |
3117 | |
4137 | |
3118 | Here is a list of things available in the C<ev> namespace: |
4138 | Here is a list of things available in the C<ev> namespace: |
3119 | |
4139 | |
3120 | =over 4 |
4140 | =over 4 |
3121 | |
4141 | |
… | |
… | |
3131 | =item C<ev::io>, C<ev::timer>, C<ev::periodic>, C<ev::idle>, C<ev::sig> etc. |
4151 | =item C<ev::io>, C<ev::timer>, C<ev::periodic>, C<ev::idle>, C<ev::sig> etc. |
3132 | |
4152 | |
3133 | For each C<ev_TYPE> watcher in F<ev.h> there is a corresponding class of |
4153 | For each C<ev_TYPE> watcher in F<ev.h> there is a corresponding class of |
3134 | the same name in the C<ev> namespace, with the exception of C<ev_signal> |
4154 | the same name in the C<ev> namespace, with the exception of C<ev_signal> |
3135 | which is called C<ev::sig> to avoid clashes with the C<signal> macro |
4155 | which is called C<ev::sig> to avoid clashes with the C<signal> macro |
3136 | defines by many implementations. |
4156 | defined by many implementations. |
3137 | |
4157 | |
3138 | All of those classes have these methods: |
4158 | All of those classes have these methods: |
3139 | |
4159 | |
3140 | =over 4 |
4160 | =over 4 |
3141 | |
4161 | |
3142 | =item ev::TYPE::TYPE () |
4162 | =item ev::TYPE::TYPE () |
3143 | |
4163 | |
3144 | =item ev::TYPE::TYPE (struct ev_loop *) |
4164 | =item ev::TYPE::TYPE (loop) |
3145 | |
4165 | |
3146 | =item ev::TYPE::~TYPE |
4166 | =item ev::TYPE::~TYPE |
3147 | |
4167 | |
3148 | The constructor (optionally) takes an event loop to associate the watcher |
4168 | The constructor (optionally) takes an event loop to associate the watcher |
3149 | with. If it is omitted, it will use C<EV_DEFAULT>. |
4169 | with. If it is omitted, it will use C<EV_DEFAULT>. |
… | |
… | |
3182 | myclass obj; |
4202 | myclass obj; |
3183 | ev::io iow; |
4203 | ev::io iow; |
3184 | iow.set <myclass, &myclass::io_cb> (&obj); |
4204 | iow.set <myclass, &myclass::io_cb> (&obj); |
3185 | |
4205 | |
3186 | =item w->set (object *) |
4206 | =item w->set (object *) |
3187 | |
|
|
3188 | This is an B<experimental> feature that might go away in a future version. |
|
|
3189 | |
4207 | |
3190 | This is a variation of a method callback - leaving out the method to call |
4208 | This is a variation of a method callback - leaving out the method to call |
3191 | will default the method to C<operator ()>, which makes it possible to use |
4209 | will default the method to C<operator ()>, which makes it possible to use |
3192 | functor objects without having to manually specify the C<operator ()> all |
4210 | functor objects without having to manually specify the C<operator ()> all |
3193 | the time. Incidentally, you can then also leave out the template argument |
4211 | the time. Incidentally, you can then also leave out the template argument |
… | |
… | |
3205 | void operator() (ev::io &w, int revents) |
4223 | void operator() (ev::io &w, int revents) |
3206 | { |
4224 | { |
3207 | ... |
4225 | ... |
3208 | } |
4226 | } |
3209 | } |
4227 | } |
3210 | |
4228 | |
3211 | myfunctor f; |
4229 | myfunctor f; |
3212 | |
4230 | |
3213 | ev::io w; |
4231 | ev::io w; |
3214 | w.set (&f); |
4232 | w.set (&f); |
3215 | |
4233 | |
… | |
… | |
3226 | Example: Use a plain function as callback. |
4244 | Example: Use a plain function as callback. |
3227 | |
4245 | |
3228 | static void io_cb (ev::io &w, int revents) { } |
4246 | static void io_cb (ev::io &w, int revents) { } |
3229 | iow.set <io_cb> (); |
4247 | iow.set <io_cb> (); |
3230 | |
4248 | |
3231 | =item w->set (struct ev_loop *) |
4249 | =item w->set (loop) |
3232 | |
4250 | |
3233 | Associates a different C<struct ev_loop> with this watcher. You can only |
4251 | Associates a different C<struct ev_loop> with this watcher. You can only |
3234 | do this when the watcher is inactive (and not pending either). |
4252 | do this when the watcher is inactive (and not pending either). |
3235 | |
4253 | |
3236 | =item w->set ([arguments]) |
4254 | =item w->set ([arguments]) |
3237 | |
4255 | |
3238 | Basically the same as C<ev_TYPE_set>, with the same arguments. Must be |
4256 | Basically the same as C<ev_TYPE_set> (except for C<ev::embed> watchers>), |
|
|
4257 | with the same arguments. Either this method or a suitable start method |
3239 | called at least once. Unlike the C counterpart, an active watcher gets |
4258 | must be called at least once. Unlike the C counterpart, an active watcher |
3240 | automatically stopped and restarted when reconfiguring it with this |
4259 | gets automatically stopped and restarted when reconfiguring it with this |
3241 | method. |
4260 | method. |
|
|
4261 | |
|
|
4262 | For C<ev::embed> watchers this method is called C<set_embed>, to avoid |
|
|
4263 | clashing with the C<set (loop)> method. |
3242 | |
4264 | |
3243 | =item w->start () |
4265 | =item w->start () |
3244 | |
4266 | |
3245 | Starts the watcher. Note that there is no C<loop> argument, as the |
4267 | Starts the watcher. Note that there is no C<loop> argument, as the |
3246 | constructor already stores the event loop. |
4268 | constructor already stores the event loop. |
3247 | |
4269 | |
|
|
4270 | =item w->start ([arguments]) |
|
|
4271 | |
|
|
4272 | Instead of calling C<set> and C<start> methods separately, it is often |
|
|
4273 | convenient to wrap them in one call. Uses the same type of arguments as |
|
|
4274 | the configure C<set> method of the watcher. |
|
|
4275 | |
3248 | =item w->stop () |
4276 | =item w->stop () |
3249 | |
4277 | |
3250 | Stops the watcher if it is active. Again, no C<loop> argument. |
4278 | Stops the watcher if it is active. Again, no C<loop> argument. |
3251 | |
4279 | |
3252 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
4280 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
… | |
… | |
3264 | |
4292 | |
3265 | =back |
4293 | =back |
3266 | |
4294 | |
3267 | =back |
4295 | =back |
3268 | |
4296 | |
3269 | Example: Define a class with an IO and idle watcher, start one of them in |
4297 | Example: Define a class with two I/O and idle watchers, start the I/O |
3270 | the constructor. |
4298 | watchers in the constructor. |
3271 | |
4299 | |
3272 | class myclass |
4300 | class myclass |
3273 | { |
4301 | { |
3274 | ev::io io ; void io_cb (ev::io &w, int revents); |
4302 | ev::io io ; void io_cb (ev::io &w, int revents); |
|
|
4303 | ev::io io2 ; void io2_cb (ev::io &w, int revents); |
3275 | ev::idle idle; void idle_cb (ev::idle &w, int revents); |
4304 | ev::idle idle; void idle_cb (ev::idle &w, int revents); |
3276 | |
4305 | |
3277 | myclass (int fd) |
4306 | myclass (int fd) |
3278 | { |
4307 | { |
3279 | io .set <myclass, &myclass::io_cb > (this); |
4308 | io .set <myclass, &myclass::io_cb > (this); |
|
|
4309 | io2 .set <myclass, &myclass::io2_cb > (this); |
3280 | idle.set <myclass, &myclass::idle_cb> (this); |
4310 | idle.set <myclass, &myclass::idle_cb> (this); |
3281 | |
4311 | |
3282 | io.start (fd, ev::READ); |
4312 | io.set (fd, ev::WRITE); // configure the watcher |
|
|
4313 | io.start (); // start it whenever convenient |
|
|
4314 | |
|
|
4315 | io2.start (fd, ev::READ); // set + start in one call |
3283 | } |
4316 | } |
3284 | }; |
4317 | }; |
3285 | |
4318 | |
3286 | |
4319 | |
3287 | =head1 OTHER LANGUAGE BINDINGS |
4320 | =head1 OTHER LANGUAGE BINDINGS |
… | |
… | |
3326 | L<http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hlibev>. |
4359 | L<http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hlibev>. |
3327 | |
4360 | |
3328 | =item D |
4361 | =item D |
3329 | |
4362 | |
3330 | Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to |
4363 | Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to |
3331 | be found at L<http://proj.llucax.com.ar/wiki/evd>. |
4364 | be found at L<http://www.llucax.com.ar/proj/ev.d/index.html>. |
3332 | |
4365 | |
3333 | =item Ocaml |
4366 | =item Ocaml |
3334 | |
4367 | |
3335 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
4368 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3336 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
4369 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
|
|
4370 | |
|
|
4371 | =item Lua |
|
|
4372 | |
|
|
4373 | Brian Maher has written a partial interface to libev for lua (at the |
|
|
4374 | time of this writing, only C<ev_io> and C<ev_timer>), to be found at |
|
|
4375 | L<http://github.com/brimworks/lua-ev>. |
|
|
4376 | |
|
|
4377 | =item Javascript |
|
|
4378 | |
|
|
4379 | Node.js (L<http://nodejs.org>) uses libev as the underlying event library. |
|
|
4380 | |
|
|
4381 | =item Others |
|
|
4382 | |
|
|
4383 | There are others, and I stopped counting. |
3337 | |
4384 | |
3338 | =back |
4385 | =back |
3339 | |
4386 | |
3340 | |
4387 | |
3341 | =head1 MACRO MAGIC |
4388 | =head1 MACRO MAGIC |
… | |
… | |
3355 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
4402 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
3356 | C<EV_A_> is used when other arguments are following. Example: |
4403 | C<EV_A_> is used when other arguments are following. Example: |
3357 | |
4404 | |
3358 | ev_unref (EV_A); |
4405 | ev_unref (EV_A); |
3359 | ev_timer_add (EV_A_ watcher); |
4406 | ev_timer_add (EV_A_ watcher); |
3360 | ev_loop (EV_A_ 0); |
4407 | ev_run (EV_A_ 0); |
3361 | |
4408 | |
3362 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
4409 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
3363 | which is often provided by the following macro. |
4410 | which is often provided by the following macro. |
3364 | |
4411 | |
3365 | =item C<EV_P>, C<EV_P_> |
4412 | =item C<EV_P>, C<EV_P_> |
… | |
… | |
3378 | suitable for use with C<EV_A>. |
4425 | suitable for use with C<EV_A>. |
3379 | |
4426 | |
3380 | =item C<EV_DEFAULT>, C<EV_DEFAULT_> |
4427 | =item C<EV_DEFAULT>, C<EV_DEFAULT_> |
3381 | |
4428 | |
3382 | Similar to the other two macros, this gives you the value of the default |
4429 | Similar to the other two macros, this gives you the value of the default |
3383 | loop, if multiple loops are supported ("ev loop default"). |
4430 | loop, if multiple loops are supported ("ev loop default"). The default loop |
|
|
4431 | will be initialised if it isn't already initialised. |
|
|
4432 | |
|
|
4433 | For non-multiplicity builds, these macros do nothing, so you always have |
|
|
4434 | to initialise the loop somewhere. |
3384 | |
4435 | |
3385 | =item C<EV_DEFAULT_UC>, C<EV_DEFAULT_UC_> |
4436 | =item C<EV_DEFAULT_UC>, C<EV_DEFAULT_UC_> |
3386 | |
4437 | |
3387 | Usage identical to C<EV_DEFAULT> and C<EV_DEFAULT_>, but requires that the |
4438 | Usage identical to C<EV_DEFAULT> and C<EV_DEFAULT_>, but requires that the |
3388 | default loop has been initialised (C<UC> == unchecked). Their behaviour |
4439 | default loop has been initialised (C<UC> == unchecked). Their behaviour |
… | |
… | |
3405 | } |
4456 | } |
3406 | |
4457 | |
3407 | ev_check check; |
4458 | ev_check check; |
3408 | ev_check_init (&check, check_cb); |
4459 | ev_check_init (&check, check_cb); |
3409 | ev_check_start (EV_DEFAULT_ &check); |
4460 | ev_check_start (EV_DEFAULT_ &check); |
3410 | ev_loop (EV_DEFAULT_ 0); |
4461 | ev_run (EV_DEFAULT_ 0); |
3411 | |
4462 | |
3412 | =head1 EMBEDDING |
4463 | =head1 EMBEDDING |
3413 | |
4464 | |
3414 | Libev can (and often is) directly embedded into host |
4465 | Libev can (and often is) directly embedded into host |
3415 | applications. Examples of applications that embed it include the Deliantra |
4466 | applications. Examples of applications that embed it include the Deliantra |
… | |
… | |
3455 | ev_vars.h |
4506 | ev_vars.h |
3456 | ev_wrap.h |
4507 | ev_wrap.h |
3457 | |
4508 | |
3458 | ev_win32.c required on win32 platforms only |
4509 | ev_win32.c required on win32 platforms only |
3459 | |
4510 | |
3460 | ev_select.c only when select backend is enabled (which is enabled by default) |
4511 | ev_select.c only when select backend is enabled |
3461 | ev_poll.c only when poll backend is enabled (disabled by default) |
4512 | ev_poll.c only when poll backend is enabled |
3462 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
4513 | ev_epoll.c only when the epoll backend is enabled |
|
|
4514 | ev_linuxaio.c only when the linux aio backend is enabled |
|
|
4515 | ev_iouring.c only when the linux io_uring backend is enabled |
3463 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
4516 | ev_kqueue.c only when the kqueue backend is enabled |
3464 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
4517 | ev_port.c only when the solaris port backend is enabled |
3465 | |
4518 | |
3466 | F<ev.c> includes the backend files directly when enabled, so you only need |
4519 | F<ev.c> includes the backend files directly when enabled, so you only need |
3467 | to compile this single file. |
4520 | to compile this single file. |
3468 | |
4521 | |
3469 | =head3 LIBEVENT COMPATIBILITY API |
4522 | =head3 LIBEVENT COMPATIBILITY API |
… | |
… | |
3495 | libev.m4 |
4548 | libev.m4 |
3496 | |
4549 | |
3497 | =head2 PREPROCESSOR SYMBOLS/MACROS |
4550 | =head2 PREPROCESSOR SYMBOLS/MACROS |
3498 | |
4551 | |
3499 | Libev can be configured via a variety of preprocessor symbols you have to |
4552 | Libev can be configured via a variety of preprocessor symbols you have to |
3500 | define before including any of its files. The default in the absence of |
4553 | define before including (or compiling) any of its files. The default in |
3501 | autoconf is documented for every option. |
4554 | the absence of autoconf is documented for every option. |
|
|
4555 | |
|
|
4556 | Symbols marked with "(h)" do not change the ABI, and can have different |
|
|
4557 | values when compiling libev vs. including F<ev.h>, so it is permissible |
|
|
4558 | to redefine them before including F<ev.h> without breaking compatibility |
|
|
4559 | to a compiled library. All other symbols change the ABI, which means all |
|
|
4560 | users of libev and the libev code itself must be compiled with compatible |
|
|
4561 | settings. |
3502 | |
4562 | |
3503 | =over 4 |
4563 | =over 4 |
3504 | |
4564 | |
|
|
4565 | =item EV_COMPAT3 (h) |
|
|
4566 | |
|
|
4567 | Backwards compatibility is a major concern for libev. This is why this |
|
|
4568 | release of libev comes with wrappers for the functions and symbols that |
|
|
4569 | have been renamed between libev version 3 and 4. |
|
|
4570 | |
|
|
4571 | You can disable these wrappers (to test compatibility with future |
|
|
4572 | versions) by defining C<EV_COMPAT3> to C<0> when compiling your |
|
|
4573 | sources. This has the additional advantage that you can drop the C<struct> |
|
|
4574 | from C<struct ev_loop> declarations, as libev will provide an C<ev_loop> |
|
|
4575 | typedef in that case. |
|
|
4576 | |
|
|
4577 | In some future version, the default for C<EV_COMPAT3> will become C<0>, |
|
|
4578 | and in some even more future version the compatibility code will be |
|
|
4579 | removed completely. |
|
|
4580 | |
3505 | =item EV_STANDALONE |
4581 | =item EV_STANDALONE (h) |
3506 | |
4582 | |
3507 | Must always be C<1> if you do not use autoconf configuration, which |
4583 | Must always be C<1> if you do not use autoconf configuration, which |
3508 | keeps libev from including F<config.h>, and it also defines dummy |
4584 | keeps libev from including F<config.h>, and it also defines dummy |
3509 | implementations for some libevent functions (such as logging, which is not |
4585 | implementations for some libevent functions (such as logging, which is not |
3510 | supported). It will also not define any of the structs usually found in |
4586 | supported). It will also not define any of the structs usually found in |
3511 | F<event.h> that are not directly supported by the libev core alone. |
4587 | F<event.h> that are not directly supported by the libev core alone. |
3512 | |
4588 | |
3513 | In stanbdalone mode, libev will still try to automatically deduce the |
4589 | In standalone mode, libev will still try to automatically deduce the |
3514 | configuration, but has to be more conservative. |
4590 | configuration, but has to be more conservative. |
|
|
4591 | |
|
|
4592 | =item EV_USE_FLOOR |
|
|
4593 | |
|
|
4594 | If defined to be C<1>, libev will use the C<floor ()> function for its |
|
|
4595 | periodic reschedule calculations, otherwise libev will fall back on a |
|
|
4596 | portable (slower) implementation. If you enable this, you usually have to |
|
|
4597 | link against libm or something equivalent. Enabling this when the C<floor> |
|
|
4598 | function is not available will fail, so the safe default is to not enable |
|
|
4599 | this. |
3515 | |
4600 | |
3516 | =item EV_USE_MONOTONIC |
4601 | =item EV_USE_MONOTONIC |
3517 | |
4602 | |
3518 | If defined to be C<1>, libev will try to detect the availability of the |
4603 | If defined to be C<1>, libev will try to detect the availability of the |
3519 | monotonic clock option at both compile time and runtime. Otherwise no |
4604 | monotonic clock option at both compile time and runtime. Otherwise no |
… | |
… | |
3556 | available and will probe for kernel support at runtime. This will improve |
4641 | available and will probe for kernel support at runtime. This will improve |
3557 | C<ev_signal> and C<ev_async> performance and reduce resource consumption. |
4642 | C<ev_signal> and C<ev_async> performance and reduce resource consumption. |
3558 | If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc |
4643 | If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc |
3559 | 2.7 or newer, otherwise disabled. |
4644 | 2.7 or newer, otherwise disabled. |
3560 | |
4645 | |
|
|
4646 | =item EV_USE_SIGNALFD |
|
|
4647 | |
|
|
4648 | If defined to be C<1>, then libev will assume that C<signalfd ()> is |
|
|
4649 | available and will probe for kernel support at runtime. This enables |
|
|
4650 | the use of EVFLAG_SIGNALFD for faster and simpler signal handling. If |
|
|
4651 | undefined, it will be enabled if the headers indicate GNU/Linux + Glibc |
|
|
4652 | 2.7 or newer, otherwise disabled. |
|
|
4653 | |
|
|
4654 | =item EV_USE_TIMERFD |
|
|
4655 | |
|
|
4656 | If defined to be C<1>, then libev will assume that C<timerfd ()> is |
|
|
4657 | available and will probe for kernel support at runtime. This allows |
|
|
4658 | libev to detect time jumps accurately. If undefined, it will be enabled |
|
|
4659 | if the headers indicate GNU/Linux + Glibc 2.8 or newer and define |
|
|
4660 | C<TFD_TIMER_CANCEL_ON_SET>, otherwise disabled. |
|
|
4661 | |
|
|
4662 | =item EV_USE_EVENTFD |
|
|
4663 | |
|
|
4664 | If defined to be C<1>, then libev will assume that C<eventfd ()> is |
|
|
4665 | available and will probe for kernel support at runtime. This will improve |
|
|
4666 | C<ev_signal> and C<ev_async> performance and reduce resource consumption. |
|
|
4667 | If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc |
|
|
4668 | 2.7 or newer, otherwise disabled. |
|
|
4669 | |
3561 | =item EV_USE_SELECT |
4670 | =item EV_USE_SELECT |
3562 | |
4671 | |
3563 | If undefined or defined to be C<1>, libev will compile in support for the |
4672 | If undefined or defined to be C<1>, libev will compile in support for the |
3564 | C<select>(2) backend. No attempt at auto-detection will be done: if no |
4673 | C<select>(2) backend. No attempt at auto-detection will be done: if no |
3565 | other method takes over, select will be it. Otherwise the select backend |
4674 | other method takes over, select will be it. Otherwise the select backend |
… | |
… | |
3583 | be used is the winsock select). This means that it will call |
4692 | be used is the winsock select). This means that it will call |
3584 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
4693 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
3585 | it is assumed that all these functions actually work on fds, even |
4694 | it is assumed that all these functions actually work on fds, even |
3586 | on win32. Should not be defined on non-win32 platforms. |
4695 | on win32. Should not be defined on non-win32 platforms. |
3587 | |
4696 | |
3588 | =item EV_FD_TO_WIN32_HANDLE |
4697 | =item EV_FD_TO_WIN32_HANDLE(fd) |
3589 | |
4698 | |
3590 | If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map |
4699 | If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map |
3591 | file descriptors to socket handles. When not defining this symbol (the |
4700 | file descriptors to socket handles. When not defining this symbol (the |
3592 | default), then libev will call C<_get_osfhandle>, which is usually |
4701 | default), then libev will call C<_get_osfhandle>, which is usually |
3593 | correct. In some cases, programs use their own file descriptor management, |
4702 | correct. In some cases, programs use their own file descriptor management, |
3594 | in which case they can provide this function to map fds to socket handles. |
4703 | in which case they can provide this function to map fds to socket handles. |
3595 | |
4704 | |
|
|
4705 | =item EV_WIN32_HANDLE_TO_FD(handle) |
|
|
4706 | |
|
|
4707 | If C<EV_SELECT_IS_WINSOCKET> then libev maps handles to file descriptors |
|
|
4708 | using the standard C<_open_osfhandle> function. For programs implementing |
|
|
4709 | their own fd to handle mapping, overwriting this function makes it easier |
|
|
4710 | to do so. This can be done by defining this macro to an appropriate value. |
|
|
4711 | |
|
|
4712 | =item EV_WIN32_CLOSE_FD(fd) |
|
|
4713 | |
|
|
4714 | If programs implement their own fd to handle mapping on win32, then this |
|
|
4715 | macro can be used to override the C<close> function, useful to unregister |
|
|
4716 | file descriptors again. Note that the replacement function has to close |
|
|
4717 | the underlying OS handle. |
|
|
4718 | |
|
|
4719 | =item EV_USE_WSASOCKET |
|
|
4720 | |
|
|
4721 | If defined to be C<1>, libev will use C<WSASocket> to create its internal |
|
|
4722 | communication socket, which works better in some environments. Otherwise, |
|
|
4723 | the normal C<socket> function will be used, which works better in other |
|
|
4724 | environments. |
|
|
4725 | |
3596 | =item EV_USE_POLL |
4726 | =item EV_USE_POLL |
3597 | |
4727 | |
3598 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
4728 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
3599 | backend. Otherwise it will be enabled on non-win32 platforms. It |
4729 | backend. Otherwise it will be enabled on non-win32 platforms. It |
3600 | takes precedence over select. |
4730 | takes precedence over select. |
… | |
… | |
3604 | If defined to be C<1>, libev will compile in support for the Linux |
4734 | If defined to be C<1>, libev will compile in support for the Linux |
3605 | C<epoll>(7) backend. Its availability will be detected at runtime, |
4735 | C<epoll>(7) backend. Its availability will be detected at runtime, |
3606 | otherwise another method will be used as fallback. This is the preferred |
4736 | otherwise another method will be used as fallback. This is the preferred |
3607 | backend for GNU/Linux systems. If undefined, it will be enabled if the |
4737 | backend for GNU/Linux systems. If undefined, it will be enabled if the |
3608 | headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
4738 | headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
|
|
4739 | |
|
|
4740 | =item EV_USE_LINUXAIO |
|
|
4741 | |
|
|
4742 | If defined to be C<1>, libev will compile in support for the Linux aio |
|
|
4743 | backend (C<EV_USE_EPOLL> must also be enabled). If undefined, it will be |
|
|
4744 | enabled on linux, otherwise disabled. |
|
|
4745 | |
|
|
4746 | =item EV_USE_IOURING |
|
|
4747 | |
|
|
4748 | If defined to be C<1>, libev will compile in support for the Linux |
|
|
4749 | io_uring backend (C<EV_USE_EPOLL> must also be enabled). Due to it's |
|
|
4750 | current limitations it has to be requested explicitly. If undefined, it |
|
|
4751 | will be enabled on linux, otherwise disabled. |
3609 | |
4752 | |
3610 | =item EV_USE_KQUEUE |
4753 | =item EV_USE_KQUEUE |
3611 | |
4754 | |
3612 | If defined to be C<1>, libev will compile in support for the BSD style |
4755 | If defined to be C<1>, libev will compile in support for the BSD style |
3613 | C<kqueue>(2) backend. Its actual availability will be detected at runtime, |
4756 | C<kqueue>(2) backend. Its actual availability will be detected at runtime, |
… | |
… | |
3635 | If defined to be C<1>, libev will compile in support for the Linux inotify |
4778 | If defined to be C<1>, libev will compile in support for the Linux inotify |
3636 | interface to speed up C<ev_stat> watchers. Its actual availability will |
4779 | interface to speed up C<ev_stat> watchers. Its actual availability will |
3637 | be detected at runtime. If undefined, it will be enabled if the headers |
4780 | be detected at runtime. If undefined, it will be enabled if the headers |
3638 | indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
4781 | indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
3639 | |
4782 | |
|
|
4783 | =item EV_NO_SMP |
|
|
4784 | |
|
|
4785 | If defined to be C<1>, libev will assume that memory is always coherent |
|
|
4786 | between threads, that is, threads can be used, but threads never run on |
|
|
4787 | different cpus (or different cpu cores). This reduces dependencies |
|
|
4788 | and makes libev faster. |
|
|
4789 | |
|
|
4790 | =item EV_NO_THREADS |
|
|
4791 | |
|
|
4792 | If defined to be C<1>, libev will assume that it will never be called from |
|
|
4793 | different threads (that includes signal handlers), which is a stronger |
|
|
4794 | assumption than C<EV_NO_SMP>, above. This reduces dependencies and makes |
|
|
4795 | libev faster. |
|
|
4796 | |
3640 | =item EV_ATOMIC_T |
4797 | =item EV_ATOMIC_T |
3641 | |
4798 | |
3642 | Libev requires an integer type (suitable for storing C<0> or C<1>) whose |
4799 | Libev requires an integer type (suitable for storing C<0> or C<1>) whose |
3643 | access is atomic with respect to other threads or signal contexts. No such |
4800 | access is atomic with respect to other threads or signal contexts. No |
3644 | type is easily found in the C language, so you can provide your own type |
4801 | such type is easily found in the C language, so you can provide your own |
3645 | that you know is safe for your purposes. It is used both for signal handler "locking" |
4802 | type that you know is safe for your purposes. It is used both for signal |
3646 | as well as for signal and thread safety in C<ev_async> watchers. |
4803 | handler "locking" as well as for signal and thread safety in C<ev_async> |
|
|
4804 | watchers. |
3647 | |
4805 | |
3648 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
4806 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
3649 | (from F<signal.h>), which is usually good enough on most platforms. |
4807 | (from F<signal.h>), which is usually good enough on most platforms. |
3650 | |
4808 | |
3651 | =item EV_H |
4809 | =item EV_H (h) |
3652 | |
4810 | |
3653 | The name of the F<ev.h> header file used to include it. The default if |
4811 | The name of the F<ev.h> header file used to include it. The default if |
3654 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
4812 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
3655 | used to virtually rename the F<ev.h> header file in case of conflicts. |
4813 | used to virtually rename the F<ev.h> header file in case of conflicts. |
3656 | |
4814 | |
3657 | =item EV_CONFIG_H |
4815 | =item EV_CONFIG_H (h) |
3658 | |
4816 | |
3659 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
4817 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
3660 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
4818 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
3661 | C<EV_H>, above. |
4819 | C<EV_H>, above. |
3662 | |
4820 | |
3663 | =item EV_EVENT_H |
4821 | =item EV_EVENT_H (h) |
3664 | |
4822 | |
3665 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
4823 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
3666 | of how the F<event.h> header can be found, the default is C<"event.h">. |
4824 | of how the F<event.h> header can be found, the default is C<"event.h">. |
3667 | |
4825 | |
3668 | =item EV_PROTOTYPES |
4826 | =item EV_PROTOTYPES (h) |
3669 | |
4827 | |
3670 | If defined to be C<0>, then F<ev.h> will not define any function |
4828 | If defined to be C<0>, then F<ev.h> will not define any function |
3671 | prototypes, but still define all the structs and other symbols. This is |
4829 | prototypes, but still define all the structs and other symbols. This is |
3672 | occasionally useful if you want to provide your own wrapper functions |
4830 | occasionally useful if you want to provide your own wrapper functions |
3673 | around libev functions. |
4831 | around libev functions. |
… | |
… | |
3678 | will have the C<struct ev_loop *> as first argument, and you can create |
4836 | will have the C<struct ev_loop *> as first argument, and you can create |
3679 | additional independent event loops. Otherwise there will be no support |
4837 | additional independent event loops. Otherwise there will be no support |
3680 | for multiple event loops and there is no first event loop pointer |
4838 | for multiple event loops and there is no first event loop pointer |
3681 | argument. Instead, all functions act on the single default loop. |
4839 | argument. Instead, all functions act on the single default loop. |
3682 | |
4840 | |
|
|
4841 | Note that C<EV_DEFAULT> and C<EV_DEFAULT_> will no longer provide a |
|
|
4842 | default loop when multiplicity is switched off - you always have to |
|
|
4843 | initialise the loop manually in this case. |
|
|
4844 | |
3683 | =item EV_MINPRI |
4845 | =item EV_MINPRI |
3684 | |
4846 | |
3685 | =item EV_MAXPRI |
4847 | =item EV_MAXPRI |
3686 | |
4848 | |
3687 | The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to |
4849 | The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to |
… | |
… | |
3695 | fine. |
4857 | fine. |
3696 | |
4858 | |
3697 | If your embedding application does not need any priorities, defining these |
4859 | If your embedding application does not need any priorities, defining these |
3698 | both to C<0> will save some memory and CPU. |
4860 | both to C<0> will save some memory and CPU. |
3699 | |
4861 | |
3700 | =item EV_PERIODIC_ENABLE |
4862 | =item EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE, |
|
|
4863 | EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE, |
|
|
4864 | EV_ASYNC_ENABLE, EV_CHILD_ENABLE. |
3701 | |
4865 | |
3702 | If undefined or defined to be C<1>, then periodic timers are supported. If |
4866 | If undefined or defined to be C<1> (and the platform supports it), then |
3703 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
4867 | the respective watcher type is supported. If defined to be C<0>, then it |
3704 | code. |
4868 | is not. Disabling watcher types mainly saves code size. |
3705 | |
4869 | |
3706 | =item EV_IDLE_ENABLE |
4870 | =item EV_FEATURES |
3707 | |
|
|
3708 | If undefined or defined to be C<1>, then idle watchers are supported. If |
|
|
3709 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
3710 | code. |
|
|
3711 | |
|
|
3712 | =item EV_EMBED_ENABLE |
|
|
3713 | |
|
|
3714 | If undefined or defined to be C<1>, then embed watchers are supported. If |
|
|
3715 | defined to be C<0>, then they are not. Embed watchers rely on most other |
|
|
3716 | watcher types, which therefore must not be disabled. |
|
|
3717 | |
|
|
3718 | =item EV_STAT_ENABLE |
|
|
3719 | |
|
|
3720 | If undefined or defined to be C<1>, then stat watchers are supported. If |
|
|
3721 | defined to be C<0>, then they are not. |
|
|
3722 | |
|
|
3723 | =item EV_FORK_ENABLE |
|
|
3724 | |
|
|
3725 | If undefined or defined to be C<1>, then fork watchers are supported. If |
|
|
3726 | defined to be C<0>, then they are not. |
|
|
3727 | |
|
|
3728 | =item EV_ASYNC_ENABLE |
|
|
3729 | |
|
|
3730 | If undefined or defined to be C<1>, then async watchers are supported. If |
|
|
3731 | defined to be C<0>, then they are not. |
|
|
3732 | |
|
|
3733 | =item EV_MINIMAL |
|
|
3734 | |
4871 | |
3735 | If you need to shave off some kilobytes of code at the expense of some |
4872 | If you need to shave off some kilobytes of code at the expense of some |
3736 | speed (but with the full API), define this symbol to C<1>. Currently this |
4873 | speed (but with the full API), you can define this symbol to request |
3737 | is used to override some inlining decisions, saves roughly 30% code size |
4874 | certain subsets of functionality. The default is to enable all features |
3738 | on amd64. It also selects a much smaller 2-heap for timer management over |
4875 | that can be enabled on the platform. |
3739 | the default 4-heap. |
|
|
3740 | |
4876 | |
3741 | You can save even more by disabling watcher types you do not need |
4877 | A typical way to use this symbol is to define it to C<0> (or to a bitset |
3742 | and setting C<EV_MAXPRI> == C<EV_MINPRI>. Also, disabling C<assert> |
4878 | with some broad features you want) and then selectively re-enable |
3743 | (C<-DNDEBUG>) will usually reduce code size a lot. |
4879 | additional parts you want, for example if you want everything minimal, |
|
|
4880 | but multiple event loop support, async and child watchers and the poll |
|
|
4881 | backend, use this: |
3744 | |
4882 | |
3745 | Defining C<EV_MINIMAL> to C<2> will additionally reduce the core API to |
4883 | #define EV_FEATURES 0 |
3746 | provide a bare-bones event library. See C<ev.h> for details on what parts |
4884 | #define EV_MULTIPLICITY 1 |
3747 | of the API are still available, and do not complain if this subset changes |
4885 | #define EV_USE_POLL 1 |
3748 | over time. |
4886 | #define EV_CHILD_ENABLE 1 |
|
|
4887 | #define EV_ASYNC_ENABLE 1 |
|
|
4888 | |
|
|
4889 | The actual value is a bitset, it can be a combination of the following |
|
|
4890 | values (by default, all of these are enabled): |
|
|
4891 | |
|
|
4892 | =over 4 |
|
|
4893 | |
|
|
4894 | =item C<1> - faster/larger code |
|
|
4895 | |
|
|
4896 | Use larger code to speed up some operations. |
|
|
4897 | |
|
|
4898 | Currently this is used to override some inlining decisions (enlarging the |
|
|
4899 | code size by roughly 30% on amd64). |
|
|
4900 | |
|
|
4901 | When optimising for size, use of compiler flags such as C<-Os> with |
|
|
4902 | gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of |
|
|
4903 | assertions. |
|
|
4904 | |
|
|
4905 | The default is off when C<__OPTIMIZE_SIZE__> is defined by your compiler |
|
|
4906 | (e.g. gcc with C<-Os>). |
|
|
4907 | |
|
|
4908 | =item C<2> - faster/larger data structures |
|
|
4909 | |
|
|
4910 | Replaces the small 2-heap for timer management by a faster 4-heap, larger |
|
|
4911 | hash table sizes and so on. This will usually further increase code size |
|
|
4912 | and can additionally have an effect on the size of data structures at |
|
|
4913 | runtime. |
|
|
4914 | |
|
|
4915 | The default is off when C<__OPTIMIZE_SIZE__> is defined by your compiler |
|
|
4916 | (e.g. gcc with C<-Os>). |
|
|
4917 | |
|
|
4918 | =item C<4> - full API configuration |
|
|
4919 | |
|
|
4920 | This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and |
|
|
4921 | enables multiplicity (C<EV_MULTIPLICITY>=1). |
|
|
4922 | |
|
|
4923 | =item C<8> - full API |
|
|
4924 | |
|
|
4925 | This enables a lot of the "lesser used" API functions. See C<ev.h> for |
|
|
4926 | details on which parts of the API are still available without this |
|
|
4927 | feature, and do not complain if this subset changes over time. |
|
|
4928 | |
|
|
4929 | =item C<16> - enable all optional watcher types |
|
|
4930 | |
|
|
4931 | Enables all optional watcher types. If you want to selectively enable |
|
|
4932 | only some watcher types other than I/O and timers (e.g. prepare, |
|
|
4933 | embed, async, child...) you can enable them manually by defining |
|
|
4934 | C<EV_watchertype_ENABLE> to C<1> instead. |
|
|
4935 | |
|
|
4936 | =item C<32> - enable all backends |
|
|
4937 | |
|
|
4938 | This enables all backends - without this feature, you need to enable at |
|
|
4939 | least one backend manually (C<EV_USE_SELECT> is a good choice). |
|
|
4940 | |
|
|
4941 | =item C<64> - enable OS-specific "helper" APIs |
|
|
4942 | |
|
|
4943 | Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by |
|
|
4944 | default. |
|
|
4945 | |
|
|
4946 | =back |
|
|
4947 | |
|
|
4948 | Compiling with C<gcc -Os -DEV_STANDALONE -DEV_USE_EPOLL=1 -DEV_FEATURES=0> |
|
|
4949 | reduces the compiled size of libev from 24.7Kb code/2.8Kb data to 6.5Kb |
|
|
4950 | code/0.3Kb data on my GNU/Linux amd64 system, while still giving you I/O |
|
|
4951 | watchers, timers and monotonic clock support. |
|
|
4952 | |
|
|
4953 | With an intelligent-enough linker (gcc+binutils are intelligent enough |
|
|
4954 | when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by |
|
|
4955 | your program might be left out as well - a binary starting a timer and an |
|
|
4956 | I/O watcher then might come out at only 5Kb. |
|
|
4957 | |
|
|
4958 | =item EV_API_STATIC |
|
|
4959 | |
|
|
4960 | If this symbol is defined (by default it is not), then all identifiers |
|
|
4961 | will have static linkage. This means that libev will not export any |
|
|
4962 | identifiers, and you cannot link against libev anymore. This can be useful |
|
|
4963 | when you embed libev, only want to use libev functions in a single file, |
|
|
4964 | and do not want its identifiers to be visible. |
|
|
4965 | |
|
|
4966 | To use this, define C<EV_API_STATIC> and include F<ev.c> in the file that |
|
|
4967 | wants to use libev. |
|
|
4968 | |
|
|
4969 | This option only works when libev is compiled with a C compiler, as C++ |
|
|
4970 | doesn't support the required declaration syntax. |
|
|
4971 | |
|
|
4972 | =item EV_AVOID_STDIO |
|
|
4973 | |
|
|
4974 | If this is set to C<1> at compiletime, then libev will avoid using stdio |
|
|
4975 | functions (printf, scanf, perror etc.). This will increase the code size |
|
|
4976 | somewhat, but if your program doesn't otherwise depend on stdio and your |
|
|
4977 | libc allows it, this avoids linking in the stdio library which is quite |
|
|
4978 | big. |
|
|
4979 | |
|
|
4980 | Note that error messages might become less precise when this option is |
|
|
4981 | enabled. |
|
|
4982 | |
|
|
4983 | =item EV_NSIG |
|
|
4984 | |
|
|
4985 | The highest supported signal number, +1 (or, the number of |
|
|
4986 | signals): Normally, libev tries to deduce the maximum number of signals |
|
|
4987 | automatically, but sometimes this fails, in which case it can be |
|
|
4988 | specified. Also, using a lower number than detected (C<32> should be |
|
|
4989 | good for about any system in existence) can save some memory, as libev |
|
|
4990 | statically allocates some 12-24 bytes per signal number. |
3749 | |
4991 | |
3750 | =item EV_PID_HASHSIZE |
4992 | =item EV_PID_HASHSIZE |
3751 | |
4993 | |
3752 | C<ev_child> watchers use a small hash table to distribute workload by |
4994 | C<ev_child> watchers use a small hash table to distribute workload by |
3753 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
4995 | pid. The default size is C<16> (or C<1> with C<EV_FEATURES> disabled), |
3754 | than enough. If you need to manage thousands of children you might want to |
4996 | usually more than enough. If you need to manage thousands of children you |
3755 | increase this value (I<must> be a power of two). |
4997 | might want to increase this value (I<must> be a power of two). |
3756 | |
4998 | |
3757 | =item EV_INOTIFY_HASHSIZE |
4999 | =item EV_INOTIFY_HASHSIZE |
3758 | |
5000 | |
3759 | C<ev_stat> watchers use a small hash table to distribute workload by |
5001 | C<ev_stat> watchers use a small hash table to distribute workload by |
3760 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
5002 | inotify watch id. The default size is C<16> (or C<1> with C<EV_FEATURES> |
3761 | usually more than enough. If you need to manage thousands of C<ev_stat> |
5003 | disabled), usually more than enough. If you need to manage thousands of |
3762 | watchers you might want to increase this value (I<must> be a power of |
5004 | C<ev_stat> watchers you might want to increase this value (I<must> be a |
3763 | two). |
5005 | power of two). |
3764 | |
5006 | |
3765 | =item EV_USE_4HEAP |
5007 | =item EV_USE_4HEAP |
3766 | |
5008 | |
3767 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
5009 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3768 | timer and periodics heaps, libev uses a 4-heap when this symbol is defined |
5010 | timer and periodics heaps, libev uses a 4-heap when this symbol is defined |
3769 | to C<1>. The 4-heap uses more complicated (longer) code but has noticeably |
5011 | to C<1>. The 4-heap uses more complicated (longer) code but has noticeably |
3770 | faster performance with many (thousands) of watchers. |
5012 | faster performance with many (thousands) of watchers. |
3771 | |
5013 | |
3772 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
5014 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3773 | (disabled). |
5015 | will be C<0>. |
3774 | |
5016 | |
3775 | =item EV_HEAP_CACHE_AT |
5017 | =item EV_HEAP_CACHE_AT |
3776 | |
5018 | |
3777 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
5019 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3778 | timer and periodics heaps, libev can cache the timestamp (I<at>) within |
5020 | timer and periodics heaps, libev can cache the timestamp (I<at>) within |
3779 | the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>), |
5021 | the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>), |
3780 | which uses 8-12 bytes more per watcher and a few hundred bytes more code, |
5022 | which uses 8-12 bytes more per watcher and a few hundred bytes more code, |
3781 | but avoids random read accesses on heap changes. This improves performance |
5023 | but avoids random read accesses on heap changes. This improves performance |
3782 | noticeably with many (hundreds) of watchers. |
5024 | noticeably with many (hundreds) of watchers. |
3783 | |
5025 | |
3784 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
5026 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3785 | (disabled). |
5027 | will be C<0>. |
3786 | |
5028 | |
3787 | =item EV_VERIFY |
5029 | =item EV_VERIFY |
3788 | |
5030 | |
3789 | Controls how much internal verification (see C<ev_loop_verify ()>) will |
5031 | Controls how much internal verification (see C<ev_verify ()>) will |
3790 | be done: If set to C<0>, no internal verification code will be compiled |
5032 | be done: If set to C<0>, no internal verification code will be compiled |
3791 | in. If set to C<1>, then verification code will be compiled in, but not |
5033 | in. If set to C<1>, then verification code will be compiled in, but not |
3792 | called. If set to C<2>, then the internal verification code will be |
5034 | called. If set to C<2>, then the internal verification code will be |
3793 | called once per loop, which can slow down libev. If set to C<3>, then the |
5035 | called once per loop, which can slow down libev. If set to C<3>, then the |
3794 | verification code will be called very frequently, which will slow down |
5036 | verification code will be called very frequently, which will slow down |
3795 | libev considerably. |
5037 | libev considerably. |
3796 | |
5038 | |
|
|
5039 | Verification errors are reported via C's C<assert> mechanism, so if you |
|
|
5040 | disable that (e.g. by defining C<NDEBUG>) then no errors will be reported. |
|
|
5041 | |
3797 | The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be |
5042 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3798 | C<0>. |
5043 | will be C<0>. |
3799 | |
5044 | |
3800 | =item EV_COMMON |
5045 | =item EV_COMMON |
3801 | |
5046 | |
3802 | By default, all watchers have a C<void *data> member. By redefining |
5047 | By default, all watchers have a C<void *data> member. By redefining |
3803 | this macro to a something else you can include more and other types of |
5048 | this macro to something else you can include more and other types of |
3804 | members. You have to define it each time you include one of the files, |
5049 | members. You have to define it each time you include one of the files, |
3805 | though, and it must be identical each time. |
5050 | though, and it must be identical each time. |
3806 | |
5051 | |
3807 | For example, the perl EV module uses something like this: |
5052 | For example, the perl EV module uses something like this: |
3808 | |
5053 | |
… | |
… | |
3861 | file. |
5106 | file. |
3862 | |
5107 | |
3863 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
5108 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
3864 | that everybody includes and which overrides some configure choices: |
5109 | that everybody includes and which overrides some configure choices: |
3865 | |
5110 | |
3866 | #define EV_MINIMAL 1 |
5111 | #define EV_FEATURES 8 |
3867 | #define EV_USE_POLL 0 |
5112 | #define EV_USE_SELECT 1 |
3868 | #define EV_MULTIPLICITY 0 |
|
|
3869 | #define EV_PERIODIC_ENABLE 0 |
5113 | #define EV_PREPARE_ENABLE 1 |
|
|
5114 | #define EV_IDLE_ENABLE 1 |
3870 | #define EV_STAT_ENABLE 0 |
5115 | #define EV_SIGNAL_ENABLE 1 |
3871 | #define EV_FORK_ENABLE 0 |
5116 | #define EV_CHILD_ENABLE 1 |
|
|
5117 | #define EV_USE_STDEXCEPT 0 |
3872 | #define EV_CONFIG_H <config.h> |
5118 | #define EV_CONFIG_H <config.h> |
3873 | #define EV_MINPRI 0 |
|
|
3874 | #define EV_MAXPRI 0 |
|
|
3875 | |
5119 | |
3876 | #include "ev++.h" |
5120 | #include "ev++.h" |
3877 | |
5121 | |
3878 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
5122 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
3879 | |
5123 | |
3880 | #include "ev_cpp.h" |
5124 | #include "ev_cpp.h" |
3881 | #include "ev.c" |
5125 | #include "ev.c" |
3882 | |
5126 | |
3883 | =head1 INTERACTION WITH OTHER PROGRAMS OR LIBRARIES |
5127 | =head1 INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT |
3884 | |
5128 | |
3885 | =head2 THREADS AND COROUTINES |
5129 | =head2 THREADS AND COROUTINES |
3886 | |
5130 | |
3887 | =head3 THREADS |
5131 | =head3 THREADS |
3888 | |
5132 | |
… | |
… | |
3939 | default loop and triggering an C<ev_async> watcher from the default loop |
5183 | default loop and triggering an C<ev_async> watcher from the default loop |
3940 | watcher callback into the event loop interested in the signal. |
5184 | watcher callback into the event loop interested in the signal. |
3941 | |
5185 | |
3942 | =back |
5186 | =back |
3943 | |
5187 | |
3944 | =head4 THREAD LOCKING EXAMPLE |
5188 | See also L</THREAD LOCKING EXAMPLE>. |
3945 | |
|
|
3946 | Here is a fictitious example of how to run an event loop in a different |
|
|
3947 | thread than where callbacks are being invoked and watchers are |
|
|
3948 | created/added/removed. |
|
|
3949 | |
|
|
3950 | For a real-world example, see the C<EV::Loop::Async> perl module, |
|
|
3951 | which uses exactly this technique (which is suited for many high-level |
|
|
3952 | languages). |
|
|
3953 | |
|
|
3954 | The example uses a pthread mutex to protect the loop data, a condition |
|
|
3955 | variable to wait for callback invocations, an async watcher to notify the |
|
|
3956 | event loop thread and an unspecified mechanism to wake up the main thread. |
|
|
3957 | |
|
|
3958 | First, you need to associate some data with the event loop: |
|
|
3959 | |
|
|
3960 | typedef struct { |
|
|
3961 | mutex_t lock; /* global loop lock */ |
|
|
3962 | ev_async async_w; |
|
|
3963 | thread_t tid; |
|
|
3964 | cond_t invoke_cv; |
|
|
3965 | } userdata; |
|
|
3966 | |
|
|
3967 | void prepare_loop (EV_P) |
|
|
3968 | { |
|
|
3969 | // for simplicity, we use a static userdata struct. |
|
|
3970 | static userdata u; |
|
|
3971 | |
|
|
3972 | ev_async_init (&u->async_w, async_cb); |
|
|
3973 | ev_async_start (EV_A_ &u->async_w); |
|
|
3974 | |
|
|
3975 | pthread_mutex_init (&u->lock, 0); |
|
|
3976 | pthread_cond_init (&u->invoke_cv, 0); |
|
|
3977 | |
|
|
3978 | // now associate this with the loop |
|
|
3979 | ev_set_userdata (EV_A_ u); |
|
|
3980 | ev_set_invoke_pending_cb (EV_A_ l_invoke); |
|
|
3981 | ev_set_loop_release_cb (EV_A_ l_release, l_acquire); |
|
|
3982 | |
|
|
3983 | // then create the thread running ev_loop |
|
|
3984 | pthread_create (&u->tid, 0, l_run, EV_A); |
|
|
3985 | } |
|
|
3986 | |
|
|
3987 | The callback for the C<ev_async> watcher does nothing: the watcher is used |
|
|
3988 | solely to wake up the event loop so it takes notice of any new watchers |
|
|
3989 | that might have been added: |
|
|
3990 | |
|
|
3991 | static void |
|
|
3992 | async_cb (EV_P_ ev_async *w, int revents) |
|
|
3993 | { |
|
|
3994 | // just used for the side effects |
|
|
3995 | } |
|
|
3996 | |
|
|
3997 | The C<l_release> and C<l_acquire> callbacks simply unlock/lock the mutex |
|
|
3998 | protecting the loop data, respectively. |
|
|
3999 | |
|
|
4000 | static void |
|
|
4001 | l_release (EV_P) |
|
|
4002 | { |
|
|
4003 | userdata *u = ev_userdata (EV_A); |
|
|
4004 | pthread_mutex_unlock (&u->lock); |
|
|
4005 | } |
|
|
4006 | |
|
|
4007 | static void |
|
|
4008 | l_acquire (EV_P) |
|
|
4009 | { |
|
|
4010 | userdata *u = ev_userdata (EV_A); |
|
|
4011 | pthread_mutex_lock (&u->lock); |
|
|
4012 | } |
|
|
4013 | |
|
|
4014 | The event loop thread first acquires the mutex, and then jumps straight |
|
|
4015 | into C<ev_loop>: |
|
|
4016 | |
|
|
4017 | void * |
|
|
4018 | l_run (void *thr_arg) |
|
|
4019 | { |
|
|
4020 | struct ev_loop *loop = (struct ev_loop *)thr_arg; |
|
|
4021 | |
|
|
4022 | l_acquire (EV_A); |
|
|
4023 | pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
|
|
4024 | ev_loop (EV_A_ 0); |
|
|
4025 | l_release (EV_A); |
|
|
4026 | |
|
|
4027 | return 0; |
|
|
4028 | } |
|
|
4029 | |
|
|
4030 | Instead of invoking all pending watchers, the C<l_invoke> callback will |
|
|
4031 | signal the main thread via some unspecified mechanism (signals? pipe |
|
|
4032 | writes? C<Async::Interrupt>?) and then waits until all pending watchers |
|
|
4033 | have been called: |
|
|
4034 | |
|
|
4035 | static void |
|
|
4036 | l_invoke (EV_P) |
|
|
4037 | { |
|
|
4038 | userdata *u = ev_userdata (EV_A); |
|
|
4039 | |
|
|
4040 | wake_up_other_thread_in_some_magic_or_not_so_magic_way (); |
|
|
4041 | |
|
|
4042 | pthread_cond_wait (&u->invoke_cv, &u->lock); |
|
|
4043 | } |
|
|
4044 | |
|
|
4045 | Now, whenever the main thread gets told to invoke pending watchers, it |
|
|
4046 | will grab the lock, call C<ev_invoke_pending> and then signal the loop |
|
|
4047 | thread to continue: |
|
|
4048 | |
|
|
4049 | static void |
|
|
4050 | real_invoke_pending (EV_P) |
|
|
4051 | { |
|
|
4052 | userdata *u = ev_userdata (EV_A); |
|
|
4053 | |
|
|
4054 | pthread_mutex_lock (&u->lock); |
|
|
4055 | ev_invoke_pending (EV_A); |
|
|
4056 | pthread_cond_signal (&u->invoke_cv); |
|
|
4057 | pthread_mutex_unlock (&u->lock); |
|
|
4058 | } |
|
|
4059 | |
|
|
4060 | Whenever you want to start/stop a watcher or do other modifications to an |
|
|
4061 | event loop, you will now have to lock: |
|
|
4062 | |
|
|
4063 | ev_timer timeout_watcher; |
|
|
4064 | userdata *u = ev_userdata (EV_A); |
|
|
4065 | |
|
|
4066 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
|
|
4067 | |
|
|
4068 | pthread_mutex_lock (&u->lock); |
|
|
4069 | ev_timer_start (EV_A_ &timeout_watcher); |
|
|
4070 | ev_async_send (EV_A_ &u->async_w); |
|
|
4071 | pthread_mutex_unlock (&u->lock); |
|
|
4072 | |
|
|
4073 | Note that sending the C<ev_async> watcher is required because otherwise |
|
|
4074 | an event loop currently blocking in the kernel will have no knowledge |
|
|
4075 | about the newly added timer. By waking up the loop it will pick up any new |
|
|
4076 | watchers in the next event loop iteration. |
|
|
4077 | |
5189 | |
4078 | =head3 COROUTINES |
5190 | =head3 COROUTINES |
4079 | |
5191 | |
4080 | Libev is very accommodating to coroutines ("cooperative threads"): |
5192 | Libev is very accommodating to coroutines ("cooperative threads"): |
4081 | libev fully supports nesting calls to its functions from different |
5193 | libev fully supports nesting calls to its functions from different |
4082 | coroutines (e.g. you can call C<ev_loop> on the same loop from two |
5194 | coroutines (e.g. you can call C<ev_run> on the same loop from two |
4083 | different coroutines, and switch freely between both coroutines running |
5195 | different coroutines, and switch freely between both coroutines running |
4084 | the loop, as long as you don't confuse yourself). The only exception is |
5196 | the loop, as long as you don't confuse yourself). The only exception is |
4085 | that you must not do this from C<ev_periodic> reschedule callbacks. |
5197 | that you must not do this from C<ev_periodic> reschedule callbacks. |
4086 | |
5198 | |
4087 | Care has been taken to ensure that libev does not keep local state inside |
5199 | Care has been taken to ensure that libev does not keep local state inside |
4088 | C<ev_loop>, and other calls do not usually allow for coroutine switches as |
5200 | C<ev_run>, and other calls do not usually allow for coroutine switches as |
4089 | they do not call any callbacks. |
5201 | they do not call any callbacks. |
4090 | |
5202 | |
4091 | =head2 COMPILER WARNINGS |
5203 | =head2 COMPILER WARNINGS |
4092 | |
5204 | |
4093 | Depending on your compiler and compiler settings, you might get no or a |
5205 | Depending on your compiler and compiler settings, you might get no or a |
… | |
… | |
4104 | maintainable. |
5216 | maintainable. |
4105 | |
5217 | |
4106 | And of course, some compiler warnings are just plain stupid, or simply |
5218 | And of course, some compiler warnings are just plain stupid, or simply |
4107 | wrong (because they don't actually warn about the condition their message |
5219 | wrong (because they don't actually warn about the condition their message |
4108 | seems to warn about). For example, certain older gcc versions had some |
5220 | seems to warn about). For example, certain older gcc versions had some |
4109 | warnings that resulted an extreme number of false positives. These have |
5221 | warnings that resulted in an extreme number of false positives. These have |
4110 | been fixed, but some people still insist on making code warn-free with |
5222 | been fixed, but some people still insist on making code warn-free with |
4111 | such buggy versions. |
5223 | such buggy versions. |
4112 | |
5224 | |
4113 | While libev is written to generate as few warnings as possible, |
5225 | While libev is written to generate as few warnings as possible, |
4114 | "warn-free" code is not a goal, and it is recommended not to build libev |
5226 | "warn-free" code is not a goal, and it is recommended not to build libev |
… | |
… | |
4150 | I suggest using suppression lists. |
5262 | I suggest using suppression lists. |
4151 | |
5263 | |
4152 | |
5264 | |
4153 | =head1 PORTABILITY NOTES |
5265 | =head1 PORTABILITY NOTES |
4154 | |
5266 | |
|
|
5267 | =head2 GNU/LINUX 32 BIT LIMITATIONS |
|
|
5268 | |
|
|
5269 | GNU/Linux is the only common platform that supports 64 bit file/large file |
|
|
5270 | interfaces but I<disables> them by default. |
|
|
5271 | |
|
|
5272 | That means that libev compiled in the default environment doesn't support |
|
|
5273 | files larger than 2GiB or so, which mainly affects C<ev_stat> watchers. |
|
|
5274 | |
|
|
5275 | Unfortunately, many programs try to work around this GNU/Linux issue |
|
|
5276 | by enabling the large file API, which makes them incompatible with the |
|
|
5277 | standard libev compiled for their system. |
|
|
5278 | |
|
|
5279 | Likewise, libev cannot enable the large file API itself as this would |
|
|
5280 | suddenly make it incompatible to the default compile time environment, |
|
|
5281 | i.e. all programs not using special compile switches. |
|
|
5282 | |
|
|
5283 | =head2 OS/X AND DARWIN BUGS |
|
|
5284 | |
|
|
5285 | The whole thing is a bug if you ask me - basically any system interface |
|
|
5286 | you touch is broken, whether it is locales, poll, kqueue or even the |
|
|
5287 | OpenGL drivers. |
|
|
5288 | |
|
|
5289 | =head3 C<kqueue> is buggy |
|
|
5290 | |
|
|
5291 | The kqueue syscall is broken in all known versions - most versions support |
|
|
5292 | only sockets, many support pipes. |
|
|
5293 | |
|
|
5294 | Libev tries to work around this by not using C<kqueue> by default on this |
|
|
5295 | rotten platform, but of course you can still ask for it when creating a |
|
|
5296 | loop - embedding a socket-only kqueue loop into a select-based one is |
|
|
5297 | probably going to work well. |
|
|
5298 | |
|
|
5299 | =head3 C<poll> is buggy |
|
|
5300 | |
|
|
5301 | Instead of fixing C<kqueue>, Apple replaced their (working) C<poll> |
|
|
5302 | implementation by something calling C<kqueue> internally around the 10.5.6 |
|
|
5303 | release, so now C<kqueue> I<and> C<poll> are broken. |
|
|
5304 | |
|
|
5305 | Libev tries to work around this by not using C<poll> by default on |
|
|
5306 | this rotten platform, but of course you can still ask for it when creating |
|
|
5307 | a loop. |
|
|
5308 | |
|
|
5309 | =head3 C<select> is buggy |
|
|
5310 | |
|
|
5311 | All that's left is C<select>, and of course Apple found a way to fuck this |
|
|
5312 | one up as well: On OS/X, C<select> actively limits the number of file |
|
|
5313 | descriptors you can pass in to 1024 - your program suddenly crashes when |
|
|
5314 | you use more. |
|
|
5315 | |
|
|
5316 | There is an undocumented "workaround" for this - defining |
|
|
5317 | C<_DARWIN_UNLIMITED_SELECT>, which libev tries to use, so select I<should> |
|
|
5318 | work on OS/X. |
|
|
5319 | |
|
|
5320 | =head2 SOLARIS PROBLEMS AND WORKAROUNDS |
|
|
5321 | |
|
|
5322 | =head3 C<errno> reentrancy |
|
|
5323 | |
|
|
5324 | The default compile environment on Solaris is unfortunately so |
|
|
5325 | thread-unsafe that you can't even use components/libraries compiled |
|
|
5326 | without C<-D_REENTRANT> in a threaded program, which, of course, isn't |
|
|
5327 | defined by default. A valid, if stupid, implementation choice. |
|
|
5328 | |
|
|
5329 | If you want to use libev in threaded environments you have to make sure |
|
|
5330 | it's compiled with C<_REENTRANT> defined. |
|
|
5331 | |
|
|
5332 | =head3 Event port backend |
|
|
5333 | |
|
|
5334 | The scalable event interface for Solaris is called "event |
|
|
5335 | ports". Unfortunately, this mechanism is very buggy in all major |
|
|
5336 | releases. If you run into high CPU usage, your program freezes or you get |
|
|
5337 | a large number of spurious wakeups, make sure you have all the relevant |
|
|
5338 | and latest kernel patches applied. No, I don't know which ones, but there |
|
|
5339 | are multiple ones to apply, and afterwards, event ports actually work |
|
|
5340 | great. |
|
|
5341 | |
|
|
5342 | If you can't get it to work, you can try running the program by setting |
|
|
5343 | the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and |
|
|
5344 | C<select> backends. |
|
|
5345 | |
|
|
5346 | =head2 AIX POLL BUG |
|
|
5347 | |
|
|
5348 | AIX unfortunately has a broken C<poll.h> header. Libev works around |
|
|
5349 | this by trying to avoid the poll backend altogether (i.e. it's not even |
|
|
5350 | compiled in), which normally isn't a big problem as C<select> works fine |
|
|
5351 | with large bitsets on AIX, and AIX is dead anyway. |
|
|
5352 | |
4155 | =head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS |
5353 | =head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS |
|
|
5354 | |
|
|
5355 | =head3 General issues |
4156 | |
5356 | |
4157 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
5357 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
4158 | requires, and its I/O model is fundamentally incompatible with the POSIX |
5358 | requires, and its I/O model is fundamentally incompatible with the POSIX |
4159 | model. Libev still offers limited functionality on this platform in |
5359 | model. Libev still offers limited functionality on this platform in |
4160 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
5360 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
4161 | descriptors. This only applies when using Win32 natively, not when using |
5361 | descriptors. This only applies when using Win32 natively, not when using |
4162 | e.g. cygwin. |
5362 | e.g. cygwin. Actually, it only applies to the microsofts own compilers, |
|
|
5363 | as every compiler comes with a slightly differently broken/incompatible |
|
|
5364 | environment. |
4163 | |
5365 | |
4164 | Lifting these limitations would basically require the full |
5366 | Lifting these limitations would basically require the full |
4165 | re-implementation of the I/O system. If you are into these kinds of |
5367 | re-implementation of the I/O system. If you are into this kind of thing, |
4166 | things, then note that glib does exactly that for you in a very portable |
5368 | then note that glib does exactly that for you in a very portable way (note |
4167 | way (note also that glib is the slowest event library known to man). |
5369 | also that glib is the slowest event library known to man). |
4168 | |
5370 | |
4169 | There is no supported compilation method available on windows except |
5371 | There is no supported compilation method available on windows except |
4170 | embedding it into other applications. |
5372 | embedding it into other applications. |
4171 | |
5373 | |
4172 | Sensible signal handling is officially unsupported by Microsoft - libev |
5374 | Sensible signal handling is officially unsupported by Microsoft - libev |
… | |
… | |
4200 | you do I<not> compile the F<ev.c> or any other embedded source files!): |
5402 | you do I<not> compile the F<ev.c> or any other embedded source files!): |
4201 | |
5403 | |
4202 | #include "evwrap.h" |
5404 | #include "evwrap.h" |
4203 | #include "ev.c" |
5405 | #include "ev.c" |
4204 | |
5406 | |
4205 | =over 4 |
|
|
4206 | |
|
|
4207 | =item The winsocket select function |
5407 | =head3 The winsocket C<select> function |
4208 | |
5408 | |
4209 | The winsocket C<select> function doesn't follow POSIX in that it |
5409 | The winsocket C<select> function doesn't follow POSIX in that it |
4210 | requires socket I<handles> and not socket I<file descriptors> (it is |
5410 | requires socket I<handles> and not socket I<file descriptors> (it is |
4211 | also extremely buggy). This makes select very inefficient, and also |
5411 | also extremely buggy). This makes select very inefficient, and also |
4212 | requires a mapping from file descriptors to socket handles (the Microsoft |
5412 | requires a mapping from file descriptors to socket handles (the Microsoft |
… | |
… | |
4221 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
5421 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
4222 | |
5422 | |
4223 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
5423 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
4224 | complexity in the O(n²) range when using win32. |
5424 | complexity in the O(n²) range when using win32. |
4225 | |
5425 | |
4226 | =item Limited number of file descriptors |
5426 | =head3 Limited number of file descriptors |
4227 | |
5427 | |
4228 | Windows has numerous arbitrary (and low) limits on things. |
5428 | Windows has numerous arbitrary (and low) limits on things. |
4229 | |
5429 | |
4230 | Early versions of winsocket's select only supported waiting for a maximum |
5430 | Early versions of winsocket's select only supported waiting for a maximum |
4231 | of C<64> handles (probably owning to the fact that all windows kernels |
5431 | of C<64> handles (probably owning to the fact that all windows kernels |
… | |
… | |
4246 | runtime libraries. This might get you to about C<512> or C<2048> sockets |
5446 | runtime libraries. This might get you to about C<512> or C<2048> sockets |
4247 | (depending on windows version and/or the phase of the moon). To get more, |
5447 | (depending on windows version and/or the phase of the moon). To get more, |
4248 | you need to wrap all I/O functions and provide your own fd management, but |
5448 | you need to wrap all I/O functions and provide your own fd management, but |
4249 | the cost of calling select (O(n²)) will likely make this unworkable. |
5449 | the cost of calling select (O(n²)) will likely make this unworkable. |
4250 | |
5450 | |
4251 | =back |
|
|
4252 | |
|
|
4253 | =head2 PORTABILITY REQUIREMENTS |
5451 | =head2 PORTABILITY REQUIREMENTS |
4254 | |
5452 | |
4255 | In addition to a working ISO-C implementation and of course the |
5453 | In addition to a working ISO-C implementation and of course the |
4256 | backend-specific APIs, libev relies on a few additional extensions: |
5454 | backend-specific APIs, libev relies on a few additional extensions: |
4257 | |
5455 | |
… | |
… | |
4263 | Libev assumes not only that all watcher pointers have the same internal |
5461 | Libev assumes not only that all watcher pointers have the same internal |
4264 | structure (guaranteed by POSIX but not by ISO C for example), but it also |
5462 | structure (guaranteed by POSIX but not by ISO C for example), but it also |
4265 | assumes that the same (machine) code can be used to call any watcher |
5463 | assumes that the same (machine) code can be used to call any watcher |
4266 | callback: The watcher callbacks have different type signatures, but libev |
5464 | callback: The watcher callbacks have different type signatures, but libev |
4267 | calls them using an C<ev_watcher *> internally. |
5465 | calls them using an C<ev_watcher *> internally. |
|
|
5466 | |
|
|
5467 | =item null pointers and integer zero are represented by 0 bytes |
|
|
5468 | |
|
|
5469 | Libev uses C<memset> to initialise structs and arrays to C<0> bytes, and |
|
|
5470 | relies on this setting pointers and integers to null. |
|
|
5471 | |
|
|
5472 | =item pointer accesses must be thread-atomic |
|
|
5473 | |
|
|
5474 | Accessing a pointer value must be atomic, it must both be readable and |
|
|
5475 | writable in one piece - this is the case on all current architectures. |
4268 | |
5476 | |
4269 | =item C<sig_atomic_t volatile> must be thread-atomic as well |
5477 | =item C<sig_atomic_t volatile> must be thread-atomic as well |
4270 | |
5478 | |
4271 | The type C<sig_atomic_t volatile> (or whatever is defined as |
5479 | The type C<sig_atomic_t volatile> (or whatever is defined as |
4272 | C<EV_ATOMIC_T>) must be atomic with respect to accesses from different |
5480 | C<EV_ATOMIC_T>) must be atomic with respect to accesses from different |
… | |
… | |
4281 | thread" or will block signals process-wide, both behaviours would |
5489 | thread" or will block signals process-wide, both behaviours would |
4282 | be compatible with libev. Interaction between C<sigprocmask> and |
5490 | be compatible with libev. Interaction between C<sigprocmask> and |
4283 | C<pthread_sigmask> could complicate things, however. |
5491 | C<pthread_sigmask> could complicate things, however. |
4284 | |
5492 | |
4285 | The most portable way to handle signals is to block signals in all threads |
5493 | The most portable way to handle signals is to block signals in all threads |
4286 | except the initial one, and run the default loop in the initial thread as |
5494 | except the initial one, and run the signal handling loop in the initial |
4287 | well. |
5495 | thread as well. |
4288 | |
5496 | |
4289 | =item C<long> must be large enough for common memory allocation sizes |
5497 | =item C<long> must be large enough for common memory allocation sizes |
4290 | |
5498 | |
4291 | To improve portability and simplify its API, libev uses C<long> internally |
5499 | To improve portability and simplify its API, libev uses C<long> internally |
4292 | instead of C<size_t> when allocating its data structures. On non-POSIX |
5500 | instead of C<size_t> when allocating its data structures. On non-POSIX |
… | |
… | |
4295 | watchers. |
5503 | watchers. |
4296 | |
5504 | |
4297 | =item C<double> must hold a time value in seconds with enough accuracy |
5505 | =item C<double> must hold a time value in seconds with enough accuracy |
4298 | |
5506 | |
4299 | The type C<double> is used to represent timestamps. It is required to |
5507 | The type C<double> is used to represent timestamps. It is required to |
4300 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
5508 | have at least 51 bits of mantissa (and 9 bits of exponent), which is |
4301 | enough for at least into the year 4000. This requirement is fulfilled by |
5509 | good enough for at least into the year 4000 with millisecond accuracy |
|
|
5510 | (the design goal for libev). This requirement is overfulfilled by |
4302 | implementations implementing IEEE 754, which is basically all existing |
5511 | implementations using IEEE 754, which is basically all existing ones. |
|
|
5512 | |
4303 | ones. With IEEE 754 doubles, you get microsecond accuracy until at least |
5513 | With IEEE 754 doubles, you get microsecond accuracy until at least the |
4304 | 2200. |
5514 | year 2255 (and millisecond accuracy till the year 287396 - by then, libev |
|
|
5515 | is either obsolete or somebody patched it to use C<long double> or |
|
|
5516 | something like that, just kidding). |
4305 | |
5517 | |
4306 | =back |
5518 | =back |
4307 | |
5519 | |
4308 | If you know of other additional requirements drop me a note. |
5520 | If you know of other additional requirements drop me a note. |
4309 | |
5521 | |
… | |
… | |
4371 | =item Processing ev_async_send: O(number_of_async_watchers) |
5583 | =item Processing ev_async_send: O(number_of_async_watchers) |
4372 | |
5584 | |
4373 | =item Processing signals: O(max_signal_number) |
5585 | =item Processing signals: O(max_signal_number) |
4374 | |
5586 | |
4375 | Sending involves a system call I<iff> there were no other C<ev_async_send> |
5587 | Sending involves a system call I<iff> there were no other C<ev_async_send> |
4376 | calls in the current loop iteration. Checking for async and signal events |
5588 | calls in the current loop iteration and the loop is currently |
|
|
5589 | blocked. Checking for async and signal events involves iterating over all |
4377 | involves iterating over all running async watchers or all signal numbers. |
5590 | running async watchers or all signal numbers. |
4378 | |
5591 | |
4379 | =back |
5592 | =back |
4380 | |
5593 | |
4381 | |
5594 | |
|
|
5595 | =head1 PORTING FROM LIBEV 3.X TO 4.X |
|
|
5596 | |
|
|
5597 | The major version 4 introduced some incompatible changes to the API. |
|
|
5598 | |
|
|
5599 | At the moment, the C<ev.h> header file provides compatibility definitions |
|
|
5600 | for all changes, so most programs should still compile. The compatibility |
|
|
5601 | layer might be removed in later versions of libev, so better update to the |
|
|
5602 | new API early than late. |
|
|
5603 | |
|
|
5604 | =over 4 |
|
|
5605 | |
|
|
5606 | =item C<EV_COMPAT3> backwards compatibility mechanism |
|
|
5607 | |
|
|
5608 | The backward compatibility mechanism can be controlled by |
|
|
5609 | C<EV_COMPAT3>. See L</"PREPROCESSOR SYMBOLS/MACROS"> in the L</EMBEDDING> |
|
|
5610 | section. |
|
|
5611 | |
|
|
5612 | =item C<ev_default_destroy> and C<ev_default_fork> have been removed |
|
|
5613 | |
|
|
5614 | These calls can be replaced easily by their C<ev_loop_xxx> counterparts: |
|
|
5615 | |
|
|
5616 | ev_loop_destroy (EV_DEFAULT_UC); |
|
|
5617 | ev_loop_fork (EV_DEFAULT); |
|
|
5618 | |
|
|
5619 | =item function/symbol renames |
|
|
5620 | |
|
|
5621 | A number of functions and symbols have been renamed: |
|
|
5622 | |
|
|
5623 | ev_loop => ev_run |
|
|
5624 | EVLOOP_NONBLOCK => EVRUN_NOWAIT |
|
|
5625 | EVLOOP_ONESHOT => EVRUN_ONCE |
|
|
5626 | |
|
|
5627 | ev_unloop => ev_break |
|
|
5628 | EVUNLOOP_CANCEL => EVBREAK_CANCEL |
|
|
5629 | EVUNLOOP_ONE => EVBREAK_ONE |
|
|
5630 | EVUNLOOP_ALL => EVBREAK_ALL |
|
|
5631 | |
|
|
5632 | EV_TIMEOUT => EV_TIMER |
|
|
5633 | |
|
|
5634 | ev_loop_count => ev_iteration |
|
|
5635 | ev_loop_depth => ev_depth |
|
|
5636 | ev_loop_verify => ev_verify |
|
|
5637 | |
|
|
5638 | Most functions working on C<struct ev_loop> objects don't have an |
|
|
5639 | C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and |
|
|
5640 | associated constants have been renamed to not collide with the C<struct |
|
|
5641 | ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme |
|
|
5642 | as all other watcher types. Note that C<ev_loop_fork> is still called |
|
|
5643 | C<ev_loop_fork> because it would otherwise clash with the C<ev_fork> |
|
|
5644 | typedef. |
|
|
5645 | |
|
|
5646 | =item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES> |
|
|
5647 | |
|
|
5648 | The preprocessor symbol C<EV_MINIMAL> has been replaced by a different |
|
|
5649 | mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile |
|
|
5650 | and work, but the library code will of course be larger. |
|
|
5651 | |
|
|
5652 | =back |
|
|
5653 | |
|
|
5654 | |
4382 | =head1 GLOSSARY |
5655 | =head1 GLOSSARY |
4383 | |
5656 | |
4384 | =over 4 |
5657 | =over 4 |
4385 | |
5658 | |
4386 | =item active |
5659 | =item active |
4387 | |
5660 | |
4388 | A watcher is active as long as it has been started (has been attached to |
5661 | A watcher is active as long as it has been started and not yet stopped. |
4389 | an event loop) but not yet stopped (disassociated from the event loop). |
5662 | See L</WATCHER STATES> for details. |
4390 | |
5663 | |
4391 | =item application |
5664 | =item application |
4392 | |
5665 | |
4393 | In this document, an application is whatever is using libev. |
5666 | In this document, an application is whatever is using libev. |
|
|
5667 | |
|
|
5668 | =item backend |
|
|
5669 | |
|
|
5670 | The part of the code dealing with the operating system interfaces. |
4394 | |
5671 | |
4395 | =item callback |
5672 | =item callback |
4396 | |
5673 | |
4397 | The address of a function that is called when some event has been |
5674 | The address of a function that is called when some event has been |
4398 | detected. Callbacks are being passed the event loop, the watcher that |
5675 | detected. Callbacks are being passed the event loop, the watcher that |
4399 | received the event, and the actual event bitset. |
5676 | received the event, and the actual event bitset. |
4400 | |
5677 | |
4401 | =item callback invocation |
5678 | =item callback/watcher invocation |
4402 | |
5679 | |
4403 | The act of calling the callback associated with a watcher. |
5680 | The act of calling the callback associated with a watcher. |
4404 | |
5681 | |
4405 | =item event |
5682 | =item event |
4406 | |
5683 | |
4407 | A change of state of some external event, such as data now being available |
5684 | A change of state of some external event, such as data now being available |
4408 | for reading on a file descriptor, time having passed or simply not having |
5685 | for reading on a file descriptor, time having passed or simply not having |
4409 | any other events happening anymore. |
5686 | any other events happening anymore. |
4410 | |
5687 | |
4411 | In libev, events are represented as single bits (such as C<EV_READ> or |
5688 | In libev, events are represented as single bits (such as C<EV_READ> or |
4412 | C<EV_TIMEOUT>). |
5689 | C<EV_TIMER>). |
4413 | |
5690 | |
4414 | =item event library |
5691 | =item event library |
4415 | |
5692 | |
4416 | A software package implementing an event model and loop. |
5693 | A software package implementing an event model and loop. |
4417 | |
5694 | |
… | |
… | |
4425 | The model used to describe how an event loop handles and processes |
5702 | The model used to describe how an event loop handles and processes |
4426 | watchers and events. |
5703 | watchers and events. |
4427 | |
5704 | |
4428 | =item pending |
5705 | =item pending |
4429 | |
5706 | |
4430 | A watcher is pending as soon as the corresponding event has been detected, |
5707 | A watcher is pending as soon as the corresponding event has been |
4431 | and stops being pending as soon as the watcher will be invoked or its |
5708 | detected. See L</WATCHER STATES> for details. |
4432 | pending status is explicitly cleared by the application. |
|
|
4433 | |
|
|
4434 | A watcher can be pending, but not active. Stopping a watcher also clears |
|
|
4435 | its pending status. |
|
|
4436 | |
5709 | |
4437 | =item real time |
5710 | =item real time |
4438 | |
5711 | |
4439 | The physical time that is observed. It is apparently strictly monotonic :) |
5712 | The physical time that is observed. It is apparently strictly monotonic :) |
4440 | |
5713 | |
4441 | =item wall-clock time |
5714 | =item wall-clock time |
4442 | |
5715 | |
4443 | The time and date as shown on clocks. Unlike real time, it can actually |
5716 | The time and date as shown on clocks. Unlike real time, it can actually |
4444 | be wrong and jump forwards and backwards, e.g. when the you adjust your |
5717 | be wrong and jump forwards and backwards, e.g. when you adjust your |
4445 | clock. |
5718 | clock. |
4446 | |
5719 | |
4447 | =item watcher |
5720 | =item watcher |
4448 | |
5721 | |
4449 | A data structure that describes interest in certain events. Watchers need |
5722 | A data structure that describes interest in certain events. Watchers need |
4450 | to be started (attached to an event loop) before they can receive events. |
5723 | to be started (attached to an event loop) before they can receive events. |
4451 | |
5724 | |
4452 | =item watcher invocation |
|
|
4453 | |
|
|
4454 | The act of calling the callback associated with a watcher. |
|
|
4455 | |
|
|
4456 | =back |
5725 | =back |
4457 | |
5726 | |
4458 | =head1 AUTHOR |
5727 | =head1 AUTHOR |
4459 | |
5728 | |
4460 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. |
5729 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael |
|
|
5730 | Magnusson and Emanuele Giaquinta, and minor corrections by many others. |
4461 | |
5731 | |