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2 | |
2 | |
3 | libev - a high performance full-featured event loop written in C |
3 | libev - a high performance full-featured event loop written in C |
4 | |
4 | |
5 | =head1 SYNOPSIS |
5 | =head1 SYNOPSIS |
6 | |
6 | |
7 | #include <ev.h> |
7 | #include <ev.h> |
8 | |
8 | |
9 | =head2 EXAMPLE PROGRAM |
9 | =head2 EXAMPLE PROGRAM |
10 | |
10 | |
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11 | // a single header file is required |
11 | #include <ev.h> |
12 | #include <ev.h> |
12 | |
13 | |
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14 | // every watcher type has its own typedef'd struct |
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15 | // with the name ev_<type> |
13 | ev_io stdin_watcher; |
16 | ev_io stdin_watcher; |
14 | ev_timer timeout_watcher; |
17 | ev_timer timeout_watcher; |
15 | |
18 | |
16 | /* called when data readable on stdin */ |
19 | // all watcher callbacks have a similar signature |
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20 | // this callback is called when data is readable on stdin |
17 | static void |
21 | static void |
18 | stdin_cb (EV_P_ struct ev_io *w, int revents) |
22 | stdin_cb (EV_P_ struct ev_io *w, int revents) |
19 | { |
23 | { |
20 | /* puts ("stdin ready"); */ |
24 | puts ("stdin ready"); |
21 | ev_io_stop (EV_A_ w); /* just a syntax example */ |
25 | // for one-shot events, one must manually stop the watcher |
22 | ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */ |
26 | // with its corresponding stop function. |
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27 | ev_io_stop (EV_A_ w); |
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28 | |
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29 | // this causes all nested ev_loop's to stop iterating |
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30 | ev_unloop (EV_A_ EVUNLOOP_ALL); |
23 | } |
31 | } |
24 | |
32 | |
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33 | // another callback, this time for a time-out |
25 | static void |
34 | static void |
26 | timeout_cb (EV_P_ struct ev_timer *w, int revents) |
35 | timeout_cb (EV_P_ struct ev_timer *w, int revents) |
27 | { |
36 | { |
28 | /* puts ("timeout"); */ |
37 | puts ("timeout"); |
29 | ev_unloop (EV_A_ EVUNLOOP_ONE); /* leave one loop call */ |
38 | // this causes the innermost ev_loop to stop iterating |
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39 | ev_unloop (EV_A_ EVUNLOOP_ONE); |
30 | } |
40 | } |
31 | |
41 | |
32 | int |
42 | int |
33 | main (void) |
43 | main (void) |
34 | { |
44 | { |
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45 | // use the default event loop unless you have special needs |
35 | struct ev_loop *loop = ev_default_loop (0); |
46 | struct ev_loop *loop = ev_default_loop (0); |
36 | |
47 | |
37 | /* initialise an io watcher, then start it */ |
48 | // initialise an io watcher, then start it |
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49 | // this one will watch for stdin to become readable |
38 | ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
50 | ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
39 | ev_io_start (loop, &stdin_watcher); |
51 | ev_io_start (loop, &stdin_watcher); |
40 | |
52 | |
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53 | // initialise a timer watcher, then start it |
41 | /* simple non-repeating 5.5 second timeout */ |
54 | // simple non-repeating 5.5 second timeout |
42 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
55 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
43 | ev_timer_start (loop, &timeout_watcher); |
56 | ev_timer_start (loop, &timeout_watcher); |
44 | |
57 | |
45 | /* loop till timeout or data ready */ |
58 | // now wait for events to arrive |
46 | ev_loop (loop, 0); |
59 | ev_loop (loop, 0); |
47 | |
60 | |
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61 | // unloop was called, so exit |
48 | return 0; |
62 | return 0; |
49 | } |
63 | } |
50 | |
64 | |
51 | =head1 DESCRIPTION |
65 | =head1 DESCRIPTION |
52 | |
66 | |
53 | The newest version of this document is also available as a html-formatted |
67 | The newest version of this document is also available as an html-formatted |
54 | web page you might find easier to navigate when reading it for the first |
68 | web page you might find easier to navigate when reading it for the first |
55 | time: L<http://cvs.schmorp.de/libev/ev.html>. |
69 | time: L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod>. |
56 | |
70 | |
57 | Libev is an event loop: you register interest in certain events (such as a |
71 | Libev is an event loop: you register interest in certain events (such as a |
58 | file descriptor being readable or a timeout occurring), and it will manage |
72 | file descriptor being readable or a timeout occurring), and it will manage |
59 | these event sources and provide your program with events. |
73 | these event sources and provide your program with events. |
60 | |
74 | |
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84 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
98 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
85 | for example). |
99 | for example). |
86 | |
100 | |
87 | =head2 CONVENTIONS |
101 | =head2 CONVENTIONS |
88 | |
102 | |
89 | Libev is very configurable. In this manual the default configuration will |
103 | Libev is very configurable. In this manual the default (and most common) |
90 | be described, which supports multiple event loops. For more info about |
104 | configuration will be described, which supports multiple event loops. For |
91 | various configuration options please have a look at B<EMBED> section in |
105 | more info about various configuration options please have a look at |
92 | this manual. If libev was configured without support for multiple event |
106 | B<EMBED> section in this manual. If libev was configured without support |
93 | loops, then all functions taking an initial argument of name C<loop> |
107 | for multiple event loops, then all functions taking an initial argument of |
94 | (which is always of type C<struct ev_loop *>) will not have this argument. |
108 | name C<loop> (which is always of type C<struct ev_loop *>) will not have |
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109 | this argument. |
95 | |
110 | |
96 | =head2 TIME REPRESENTATION |
111 | =head2 TIME REPRESENTATION |
97 | |
112 | |
98 | Libev represents time as a single floating point number, representing the |
113 | Libev represents time as a single floating point number, representing the |
99 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
114 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
100 | the beginning of 1970, details are complicated, don't ask). This type is |
115 | the beginning of 1970, details are complicated, don't ask). This type is |
101 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
116 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
102 | to the C<double> type in C, and when you need to do any calculations on |
117 | to the C<double> type in C, and when you need to do any calculations on |
103 | it, you should treat it as some floatingpoint value. Unlike the name |
118 | it, you should treat it as some floating point value. Unlike the name |
104 | component C<stamp> might indicate, it is also used for time differences |
119 | component C<stamp> might indicate, it is also used for time differences |
105 | throughout libev. |
120 | throughout libev. |
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121 | |
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122 | =head1 ERROR HANDLING |
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123 | |
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124 | Libev knows three classes of errors: operating system errors, usage errors |
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125 | and internal errors (bugs). |
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126 | |
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127 | When libev catches an operating system error it cannot handle (for example |
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128 | a system call indicating a condition libev cannot fix), it calls the callback |
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129 | set via C<ev_set_syserr_cb>, which is supposed to fix the problem or |
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130 | abort. The default is to print a diagnostic message and to call C<abort |
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131 | ()>. |
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132 | |
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133 | When libev detects a usage error such as a negative timer interval, then |
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134 | it will print a diagnostic message and abort (via the C<assert> mechanism, |
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135 | so C<NDEBUG> will disable this checking): these are programming errors in |
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136 | the libev caller and need to be fixed there. |
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137 | |
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138 | Libev also has a few internal error-checking C<assert>ions, and also has |
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139 | extensive consistency checking code. These do not trigger under normal |
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140 | circumstances, as they indicate either a bug in libev or worse. |
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141 | |
106 | |
142 | |
107 | =head1 GLOBAL FUNCTIONS |
143 | =head1 GLOBAL FUNCTIONS |
108 | |
144 | |
109 | These functions can be called anytime, even before initialising the |
145 | These functions can be called anytime, even before initialising the |
110 | library in any way. |
146 | library in any way. |
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119 | |
155 | |
120 | =item ev_sleep (ev_tstamp interval) |
156 | =item ev_sleep (ev_tstamp interval) |
121 | |
157 | |
122 | Sleep for the given interval: The current thread will be blocked until |
158 | Sleep for the given interval: The current thread will be blocked until |
123 | either it is interrupted or the given time interval has passed. Basically |
159 | either it is interrupted or the given time interval has passed. Basically |
124 | this is a subsecond-resolution C<sleep ()>. |
160 | this is a sub-second-resolution C<sleep ()>. |
125 | |
161 | |
126 | =item int ev_version_major () |
162 | =item int ev_version_major () |
127 | |
163 | |
128 | =item int ev_version_minor () |
164 | =item int ev_version_minor () |
129 | |
165 | |
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142 | not a problem. |
178 | not a problem. |
143 | |
179 | |
144 | Example: Make sure we haven't accidentally been linked against the wrong |
180 | Example: Make sure we haven't accidentally been linked against the wrong |
145 | version. |
181 | version. |
146 | |
182 | |
147 | assert (("libev version mismatch", |
183 | assert (("libev version mismatch", |
148 | ev_version_major () == EV_VERSION_MAJOR |
184 | ev_version_major () == EV_VERSION_MAJOR |
149 | && ev_version_minor () >= EV_VERSION_MINOR)); |
185 | && ev_version_minor () >= EV_VERSION_MINOR)); |
150 | |
186 | |
151 | =item unsigned int ev_supported_backends () |
187 | =item unsigned int ev_supported_backends () |
152 | |
188 | |
153 | Return the set of all backends (i.e. their corresponding C<EV_BACKEND_*> |
189 | Return the set of all backends (i.e. their corresponding C<EV_BACKEND_*> |
154 | value) compiled into this binary of libev (independent of their |
190 | value) compiled into this binary of libev (independent of their |
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156 | a description of the set values. |
192 | a description of the set values. |
157 | |
193 | |
158 | Example: make sure we have the epoll method, because yeah this is cool and |
194 | Example: make sure we have the epoll method, because yeah this is cool and |
159 | a must have and can we have a torrent of it please!!!11 |
195 | a must have and can we have a torrent of it please!!!11 |
160 | |
196 | |
161 | assert (("sorry, no epoll, no sex", |
197 | assert (("sorry, no epoll, no sex", |
162 | ev_supported_backends () & EVBACKEND_EPOLL)); |
198 | ev_supported_backends () & EVBACKEND_EPOLL)); |
163 | |
199 | |
164 | =item unsigned int ev_recommended_backends () |
200 | =item unsigned int ev_recommended_backends () |
165 | |
201 | |
166 | Return the set of all backends compiled into this binary of libev and also |
202 | Return the set of all backends compiled into this binary of libev and also |
167 | recommended for this platform. This set is often smaller than the one |
203 | recommended for this platform. This set is often smaller than the one |
168 | returned by C<ev_supported_backends>, as for example kqueue is broken on |
204 | returned by C<ev_supported_backends>, as for example kqueue is broken on |
169 | most BSDs and will not be autodetected unless you explicitly request it |
205 | most BSDs and will not be auto-detected unless you explicitly request it |
170 | (assuming you know what you are doing). This is the set of backends that |
206 | (assuming you know what you are doing). This is the set of backends that |
171 | libev will probe for if you specify no backends explicitly. |
207 | libev will probe for if you specify no backends explicitly. |
172 | |
208 | |
173 | =item unsigned int ev_embeddable_backends () |
209 | =item unsigned int ev_embeddable_backends () |
174 | |
210 | |
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181 | See the description of C<ev_embed> watchers for more info. |
217 | See the description of C<ev_embed> watchers for more info. |
182 | |
218 | |
183 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
219 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
184 | |
220 | |
185 | Sets the allocation function to use (the prototype is similar - the |
221 | Sets the allocation function to use (the prototype is similar - the |
186 | semantics is identical - to the realloc C function). It is used to |
222 | semantics are identical to the C<realloc> C89/SuS/POSIX function). It is |
187 | allocate and free memory (no surprises here). If it returns zero when |
223 | used to allocate and free memory (no surprises here). If it returns zero |
188 | memory needs to be allocated, the library might abort or take some |
224 | when memory needs to be allocated (C<size != 0>), the library might abort |
189 | potentially destructive action. The default is your system realloc |
225 | or take some potentially destructive action. |
190 | function. |
226 | |
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227 | Since some systems (at least OpenBSD and Darwin) fail to implement |
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228 | correct C<realloc> semantics, libev will use a wrapper around the system |
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229 | C<realloc> and C<free> functions by default. |
191 | |
230 | |
192 | You could override this function in high-availability programs to, say, |
231 | You could override this function in high-availability programs to, say, |
193 | free some memory if it cannot allocate memory, to use a special allocator, |
232 | free some memory if it cannot allocate memory, to use a special allocator, |
194 | or even to sleep a while and retry until some memory is available. |
233 | or even to sleep a while and retry until some memory is available. |
195 | |
234 | |
196 | Example: Replace the libev allocator with one that waits a bit and then |
235 | Example: Replace the libev allocator with one that waits a bit and then |
197 | retries). |
236 | retries (example requires a standards-compliant C<realloc>). |
198 | |
237 | |
199 | static void * |
238 | static void * |
200 | persistent_realloc (void *ptr, size_t size) |
239 | persistent_realloc (void *ptr, size_t size) |
201 | { |
240 | { |
202 | for (;;) |
241 | for (;;) |
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213 | ... |
252 | ... |
214 | ev_set_allocator (persistent_realloc); |
253 | ev_set_allocator (persistent_realloc); |
215 | |
254 | |
216 | =item ev_set_syserr_cb (void (*cb)(const char *msg)); |
255 | =item ev_set_syserr_cb (void (*cb)(const char *msg)); |
217 | |
256 | |
218 | Set the callback function to call on a retryable syscall error (such |
257 | Set the callback function to call on a retryable system call error (such |
219 | as failed select, poll, epoll_wait). The message is a printable string |
258 | as failed select, poll, epoll_wait). The message is a printable string |
220 | indicating the system call or subsystem causing the problem. If this |
259 | indicating the system call or subsystem causing the problem. If this |
221 | callback is set, then libev will expect it to remedy the sitution, no |
260 | callback is set, then libev will expect it to remedy the situation, no |
222 | matter what, when it returns. That is, libev will generally retry the |
261 | matter what, when it returns. That is, libev will generally retry the |
223 | requested operation, or, if the condition doesn't go away, do bad stuff |
262 | requested operation, or, if the condition doesn't go away, do bad stuff |
224 | (such as abort). |
263 | (such as abort). |
225 | |
264 | |
226 | Example: This is basically the same thing that libev does internally, too. |
265 | Example: This is basically the same thing that libev does internally, too. |
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240 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
279 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
241 | |
280 | |
242 | An event loop is described by a C<struct ev_loop *>. The library knows two |
281 | An event loop is described by a C<struct ev_loop *>. The library knows two |
243 | types of such loops, the I<default> loop, which supports signals and child |
282 | types of such loops, the I<default> loop, which supports signals and child |
244 | events, and dynamically created loops which do not. |
283 | events, and dynamically created loops which do not. |
245 | |
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246 | If you use threads, a common model is to run the default event loop |
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247 | in your main thread (or in a separate thread) and for each thread you |
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248 | create, you also create another event loop. Libev itself does no locking |
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249 | whatsoever, so if you mix calls to the same event loop in different |
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250 | threads, make sure you lock (this is usually a bad idea, though, even if |
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251 | done correctly, because it's hideous and inefficient). |
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252 | |
284 | |
253 | =over 4 |
285 | =over 4 |
254 | |
286 | |
255 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
287 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
256 | |
288 | |
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260 | flags. If that is troubling you, check C<ev_backend ()> afterwards). |
292 | flags. If that is troubling you, check C<ev_backend ()> afterwards). |
261 | |
293 | |
262 | If you don't know what event loop to use, use the one returned from this |
294 | If you don't know what event loop to use, use the one returned from this |
263 | function. |
295 | function. |
264 | |
296 | |
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297 | Note that this function is I<not> thread-safe, so if you want to use it |
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298 | from multiple threads, you have to lock (note also that this is unlikely, |
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299 | as loops cannot bes hared easily between threads anyway). |
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300 | |
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301 | The default loop is the only loop that can handle C<ev_signal> and |
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302 | C<ev_child> watchers, and to do this, it always registers a handler |
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303 | for C<SIGCHLD>. If this is a problem for your application you can either |
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304 | create a dynamic loop with C<ev_loop_new> that doesn't do that, or you |
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305 | can simply overwrite the C<SIGCHLD> signal handler I<after> calling |
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306 | C<ev_default_init>. |
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307 | |
265 | The flags argument can be used to specify special behaviour or specific |
308 | The flags argument can be used to specify special behaviour or specific |
266 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
309 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
267 | |
310 | |
268 | The following flags are supported: |
311 | The following flags are supported: |
269 | |
312 | |
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274 | The default flags value. Use this if you have no clue (it's the right |
317 | The default flags value. Use this if you have no clue (it's the right |
275 | thing, believe me). |
318 | thing, believe me). |
276 | |
319 | |
277 | =item C<EVFLAG_NOENV> |
320 | =item C<EVFLAG_NOENV> |
278 | |
321 | |
279 | If this flag bit is ored into the flag value (or the program runs setuid |
322 | If this flag bit is or'ed into the flag value (or the program runs setuid |
280 | or setgid) then libev will I<not> look at the environment variable |
323 | or setgid) then libev will I<not> look at the environment variable |
281 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
324 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
282 | override the flags completely if it is found in the environment. This is |
325 | override the flags completely if it is found in the environment. This is |
283 | useful to try out specific backends to test their performance, or to work |
326 | useful to try out specific backends to test their performance, or to work |
284 | around bugs. |
327 | around bugs. |
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290 | enabling this flag. |
333 | enabling this flag. |
291 | |
334 | |
292 | This works by calling C<getpid ()> on every iteration of the loop, |
335 | This works by calling C<getpid ()> on every iteration of the loop, |
293 | and thus this might slow down your event loop if you do a lot of loop |
336 | and thus this might slow down your event loop if you do a lot of loop |
294 | iterations and little real work, but is usually not noticeable (on my |
337 | iterations and little real work, but is usually not noticeable (on my |
295 | Linux system for example, C<getpid> is actually a simple 5-insn sequence |
338 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence |
296 | without a syscall and thus I<very> fast, but my Linux system also has |
339 | without a system call and thus I<very> fast, but my GNU/Linux system also has |
297 | C<pthread_atfork> which is even faster). |
340 | C<pthread_atfork> which is even faster). |
298 | |
341 | |
299 | The big advantage of this flag is that you can forget about fork (and |
342 | The big advantage of this flag is that you can forget about fork (and |
300 | forget about forgetting to tell libev about forking) when you use this |
343 | forget about forgetting to tell libev about forking) when you use this |
301 | flag. |
344 | flag. |
302 | |
345 | |
303 | This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS> |
346 | This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS> |
304 | environment variable. |
347 | environment variable. |
305 | |
348 | |
306 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
349 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
307 | |
350 | |
308 | This is your standard select(2) backend. Not I<completely> standard, as |
351 | This is your standard select(2) backend. Not I<completely> standard, as |
… | |
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310 | but if that fails, expect a fairly low limit on the number of fds when |
353 | but if that fails, expect a fairly low limit on the number of fds when |
311 | using this backend. It doesn't scale too well (O(highest_fd)), but its |
354 | using this backend. It doesn't scale too well (O(highest_fd)), but its |
312 | usually the fastest backend for a low number of (low-numbered :) fds. |
355 | usually the fastest backend for a low number of (low-numbered :) fds. |
313 | |
356 | |
314 | To get good performance out of this backend you need a high amount of |
357 | To get good performance out of this backend you need a high amount of |
315 | parallelity (most of the file descriptors should be busy). If you are |
358 | parallelism (most of the file descriptors should be busy). If you are |
316 | writing a server, you should C<accept ()> in a loop to accept as many |
359 | writing a server, you should C<accept ()> in a loop to accept as many |
317 | connections as possible during one iteration. You might also want to have |
360 | connections as possible during one iteration. You might also want to have |
318 | a look at C<ev_set_io_collect_interval ()> to increase the amount of |
361 | a look at C<ev_set_io_collect_interval ()> to increase the amount of |
319 | readyness notifications you get per iteration. |
362 | readiness notifications you get per iteration. |
320 | |
363 | |
321 | =item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows) |
364 | =item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows) |
322 | |
365 | |
323 | And this is your standard poll(2) backend. It's more complicated |
366 | And this is your standard poll(2) backend. It's more complicated |
324 | than select, but handles sparse fds better and has no artificial |
367 | than select, but handles sparse fds better and has no artificial |
… | |
… | |
332 | For few fds, this backend is a bit little slower than poll and select, |
375 | For few fds, this backend is a bit little slower than poll and select, |
333 | but it scales phenomenally better. While poll and select usually scale |
376 | but it scales phenomenally better. While poll and select usually scale |
334 | like O(total_fds) where n is the total number of fds (or the highest fd), |
377 | like O(total_fds) where n is the total number of fds (or the highest fd), |
335 | epoll scales either O(1) or O(active_fds). The epoll design has a number |
378 | epoll scales either O(1) or O(active_fds). The epoll design has a number |
336 | of shortcomings, such as silently dropping events in some hard-to-detect |
379 | of shortcomings, such as silently dropping events in some hard-to-detect |
337 | cases and rewiring a syscall per fd change, no fork support and bad |
380 | cases and requiring a system call per fd change, no fork support and bad |
338 | support for dup. |
381 | support for dup. |
339 | |
382 | |
340 | While stopping, setting and starting an I/O watcher in the same iteration |
383 | While stopping, setting and starting an I/O watcher in the same iteration |
341 | will result in some caching, there is still a syscall per such incident |
384 | will result in some caching, there is still a system call per such incident |
342 | (because the fd could point to a different file description now), so its |
385 | (because the fd could point to a different file description now), so its |
343 | best to avoid that. Also, C<dup ()>'ed file descriptors might not work |
386 | best to avoid that. Also, C<dup ()>'ed file descriptors might not work |
344 | very well if you register events for both fds. |
387 | very well if you register events for both fds. |
345 | |
388 | |
346 | Please note that epoll sometimes generates spurious notifications, so you |
389 | Please note that epoll sometimes generates spurious notifications, so you |
… | |
… | |
349 | |
392 | |
350 | Best performance from this backend is achieved by not unregistering all |
393 | Best performance from this backend is achieved by not unregistering all |
351 | watchers for a file descriptor until it has been closed, if possible, i.e. |
394 | watchers for a file descriptor until it has been closed, if possible, i.e. |
352 | keep at least one watcher active per fd at all times. |
395 | keep at least one watcher active per fd at all times. |
353 | |
396 | |
354 | While nominally embeddeble in other event loops, this feature is broken in |
397 | While nominally embeddable in other event loops, this feature is broken in |
355 | all kernel versions tested so far. |
398 | all kernel versions tested so far. |
356 | |
399 | |
357 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
400 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
358 | |
401 | |
359 | Kqueue deserves special mention, as at the time of this writing, it |
402 | Kqueue deserves special mention, as at the time of this writing, it |
360 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
403 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
361 | with anything but sockets and pipes, except on Darwin, where of course |
404 | with anything but sockets and pipes, except on Darwin, where of course |
362 | it's completely useless). For this reason it's not being "autodetected" |
405 | it's completely useless). For this reason it's not being "auto-detected" |
363 | unless you explicitly specify it explicitly in the flags (i.e. using |
406 | unless you explicitly specify it explicitly in the flags (i.e. using |
364 | C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough) |
407 | C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough) |
365 | system like NetBSD. |
408 | system like NetBSD. |
366 | |
409 | |
367 | You still can embed kqueue into a normal poll or select backend and use it |
410 | You still can embed kqueue into a normal poll or select backend and use it |
… | |
… | |
369 | the target platform). See C<ev_embed> watchers for more info. |
412 | the target platform). See C<ev_embed> watchers for more info. |
370 | |
413 | |
371 | It scales in the same way as the epoll backend, but the interface to the |
414 | It scales in the same way as the epoll backend, but the interface to the |
372 | kernel is more efficient (which says nothing about its actual speed, of |
415 | kernel is more efficient (which says nothing about its actual speed, of |
373 | course). While stopping, setting and starting an I/O watcher does never |
416 | course). While stopping, setting and starting an I/O watcher does never |
374 | cause an extra syscall as with C<EVBACKEND_EPOLL>, it still adds up to |
417 | cause an extra system call as with C<EVBACKEND_EPOLL>, it still adds up to |
375 | two event changes per incident, support for C<fork ()> is very bad and it |
418 | two event changes per incident, support for C<fork ()> is very bad and it |
376 | drops fds silently in similarly hard-to-detect cases. |
419 | drops fds silently in similarly hard-to-detect cases. |
377 | |
420 | |
378 | This backend usually performs well under most conditions. |
421 | This backend usually performs well under most conditions. |
379 | |
422 | |
… | |
… | |
394 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
437 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
395 | |
438 | |
396 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
439 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
397 | it's really slow, but it still scales very well (O(active_fds)). |
440 | it's really slow, but it still scales very well (O(active_fds)). |
398 | |
441 | |
399 | Please note that solaris event ports can deliver a lot of spurious |
442 | Please note that Solaris event ports can deliver a lot of spurious |
400 | notifications, so you need to use non-blocking I/O or other means to avoid |
443 | notifications, so you need to use non-blocking I/O or other means to avoid |
401 | blocking when no data (or space) is available. |
444 | blocking when no data (or space) is available. |
402 | |
445 | |
403 | While this backend scales well, it requires one system call per active |
446 | While this backend scales well, it requires one system call per active |
404 | file descriptor per loop iteration. For small and medium numbers of file |
447 | file descriptor per loop iteration. For small and medium numbers of file |
405 | descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend |
448 | descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend |
406 | might perform better. |
449 | might perform better. |
407 | |
450 | |
|
|
451 | On the positive side, ignoring the spurious readiness notifications, this |
|
|
452 | backend actually performed to specification in all tests and is fully |
|
|
453 | embeddable, which is a rare feat among the OS-specific backends. |
|
|
454 | |
408 | =item C<EVBACKEND_ALL> |
455 | =item C<EVBACKEND_ALL> |
409 | |
456 | |
410 | Try all backends (even potentially broken ones that wouldn't be tried |
457 | Try all backends (even potentially broken ones that wouldn't be tried |
411 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
458 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
412 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
459 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
413 | |
460 | |
414 | It is definitely not recommended to use this flag. |
461 | It is definitely not recommended to use this flag. |
415 | |
462 | |
416 | =back |
463 | =back |
417 | |
464 | |
418 | If one or more of these are ored into the flags value, then only these |
465 | If one or more of these are or'ed into the flags value, then only these |
419 | backends will be tried (in the reverse order as given here). If none are |
466 | backends will be tried (in the reverse order as listed here). If none are |
420 | specified, most compiled-in backend will be tried, usually in reverse |
467 | specified, all backends in C<ev_recommended_backends ()> will be tried. |
421 | order of their flag values :) |
|
|
422 | |
468 | |
423 | The most typical usage is like this: |
469 | The most typical usage is like this: |
424 | |
470 | |
425 | if (!ev_default_loop (0)) |
471 | if (!ev_default_loop (0)) |
426 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
472 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
427 | |
473 | |
428 | Restrict libev to the select and poll backends, and do not allow |
474 | Restrict libev to the select and poll backends, and do not allow |
429 | environment settings to be taken into account: |
475 | environment settings to be taken into account: |
430 | |
476 | |
431 | ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
477 | ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
432 | |
478 | |
433 | Use whatever libev has to offer, but make sure that kqueue is used if |
479 | Use whatever libev has to offer, but make sure that kqueue is used if |
434 | available (warning, breaks stuff, best use only with your own private |
480 | available (warning, breaks stuff, best use only with your own private |
435 | event loop and only if you know the OS supports your types of fds): |
481 | event loop and only if you know the OS supports your types of fds): |
436 | |
482 | |
437 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
483 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
438 | |
484 | |
439 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
485 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
440 | |
486 | |
441 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
487 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
442 | always distinct from the default loop. Unlike the default loop, it cannot |
488 | always distinct from the default loop. Unlike the default loop, it cannot |
443 | handle signal and child watchers, and attempts to do so will be greeted by |
489 | handle signal and child watchers, and attempts to do so will be greeted by |
444 | undefined behaviour (or a failed assertion if assertions are enabled). |
490 | undefined behaviour (or a failed assertion if assertions are enabled). |
445 | |
491 | |
|
|
492 | Note that this function I<is> thread-safe, and the recommended way to use |
|
|
493 | libev with threads is indeed to create one loop per thread, and using the |
|
|
494 | default loop in the "main" or "initial" thread. |
|
|
495 | |
446 | Example: Try to create a event loop that uses epoll and nothing else. |
496 | Example: Try to create a event loop that uses epoll and nothing else. |
447 | |
497 | |
448 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
498 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
449 | if (!epoller) |
499 | if (!epoller) |
450 | fatal ("no epoll found here, maybe it hides under your chair"); |
500 | fatal ("no epoll found here, maybe it hides under your chair"); |
451 | |
501 | |
452 | =item ev_default_destroy () |
502 | =item ev_default_destroy () |
453 | |
503 | |
454 | Destroys the default loop again (frees all memory and kernel state |
504 | Destroys the default loop again (frees all memory and kernel state |
455 | etc.). None of the active event watchers will be stopped in the normal |
505 | etc.). None of the active event watchers will be stopped in the normal |
456 | sense, so e.g. C<ev_is_active> might still return true. It is your |
506 | sense, so e.g. C<ev_is_active> might still return true. It is your |
457 | responsibility to either stop all watchers cleanly yoursef I<before> |
507 | responsibility to either stop all watchers cleanly yourself I<before> |
458 | calling this function, or cope with the fact afterwards (which is usually |
508 | calling this function, or cope with the fact afterwards (which is usually |
459 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
509 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
460 | for example). |
510 | for example). |
461 | |
511 | |
462 | Note that certain global state, such as signal state, will not be freed by |
512 | Note that certain global state, such as signal state, will not be freed by |
… | |
… | |
473 | Like C<ev_default_destroy>, but destroys an event loop created by an |
523 | Like C<ev_default_destroy>, but destroys an event loop created by an |
474 | earlier call to C<ev_loop_new>. |
524 | earlier call to C<ev_loop_new>. |
475 | |
525 | |
476 | =item ev_default_fork () |
526 | =item ev_default_fork () |
477 | |
527 | |
|
|
528 | This function sets a flag that causes subsequent C<ev_loop> iterations |
478 | This function reinitialises the kernel state for backends that have |
529 | to reinitialise the kernel state for backends that have one. Despite the |
479 | one. Despite the name, you can call it anytime, but it makes most sense |
530 | name, you can call it anytime, but it makes most sense after forking, in |
480 | after forking, in either the parent or child process (or both, but that |
531 | the child process (or both child and parent, but that again makes little |
481 | again makes little sense). |
532 | sense). You I<must> call it in the child before using any of the libev |
|
|
533 | functions, and it will only take effect at the next C<ev_loop> iteration. |
482 | |
534 | |
483 | You I<must> call this function in the child process after forking if and |
535 | On the other hand, you only need to call this function in the child |
484 | only if you want to use the event library in both processes. If you just |
536 | process if and only if you want to use the event library in the child. If |
485 | fork+exec, you don't have to call it. |
537 | you just fork+exec, you don't have to call it at all. |
486 | |
538 | |
487 | The function itself is quite fast and it's usually not a problem to call |
539 | The function itself is quite fast and it's usually not a problem to call |
488 | it just in case after a fork. To make this easy, the function will fit in |
540 | it just in case after a fork. To make this easy, the function will fit in |
489 | quite nicely into a call to C<pthread_atfork>: |
541 | quite nicely into a call to C<pthread_atfork>: |
490 | |
542 | |
491 | pthread_atfork (0, 0, ev_default_fork); |
543 | pthread_atfork (0, 0, ev_default_fork); |
492 | |
544 | |
493 | At the moment, C<EVBACKEND_SELECT> and C<EVBACKEND_POLL> are safe to use |
|
|
494 | without calling this function, so if you force one of those backends you |
|
|
495 | do not need to care. |
|
|
496 | |
|
|
497 | =item ev_loop_fork (loop) |
545 | =item ev_loop_fork (loop) |
498 | |
546 | |
499 | Like C<ev_default_fork>, but acts on an event loop created by |
547 | Like C<ev_default_fork>, but acts on an event loop created by |
500 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
548 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
501 | after fork, and how you do this is entirely your own problem. |
549 | after fork, and how you do this is entirely your own problem. |
|
|
550 | |
|
|
551 | =item int ev_is_default_loop (loop) |
|
|
552 | |
|
|
553 | Returns true when the given loop actually is the default loop, false otherwise. |
502 | |
554 | |
503 | =item unsigned int ev_loop_count (loop) |
555 | =item unsigned int ev_loop_count (loop) |
504 | |
556 | |
505 | Returns the count of loop iterations for the loop, which is identical to |
557 | Returns the count of loop iterations for the loop, which is identical to |
506 | the number of times libev did poll for new events. It starts at C<0> and |
558 | the number of times libev did poll for new events. It starts at C<0> and |
… | |
… | |
541 | A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle |
593 | A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle |
542 | those events and any outstanding ones, but will not block your process in |
594 | those events and any outstanding ones, but will not block your process in |
543 | case there are no events and will return after one iteration of the loop. |
595 | case there are no events and will return after one iteration of the loop. |
544 | |
596 | |
545 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
597 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
546 | neccessary) and will handle those and any outstanding ones. It will block |
598 | necessary) and will handle those and any outstanding ones. It will block |
547 | your process until at least one new event arrives, and will return after |
599 | your process until at least one new event arrives, and will return after |
548 | one iteration of the loop. This is useful if you are waiting for some |
600 | one iteration of the loop. This is useful if you are waiting for some |
549 | external event in conjunction with something not expressible using other |
601 | external event in conjunction with something not expressible using other |
550 | libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is |
602 | libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is |
551 | usually a better approach for this kind of thing. |
603 | usually a better approach for this kind of thing. |
552 | |
604 | |
553 | Here are the gory details of what C<ev_loop> does: |
605 | Here are the gory details of what C<ev_loop> does: |
554 | |
606 | |
555 | - Before the first iteration, call any pending watchers. |
607 | - Before the first iteration, call any pending watchers. |
556 | * If EVFLAG_FORKCHECK was used, check for a fork. |
608 | * If EVFLAG_FORKCHECK was used, check for a fork. |
557 | - If a fork was detected, queue and call all fork watchers. |
609 | - If a fork was detected (by any means), queue and call all fork watchers. |
558 | - Queue and call all prepare watchers. |
610 | - Queue and call all prepare watchers. |
559 | - If we have been forked, recreate the kernel state. |
611 | - If we have been forked, detach and recreate the kernel state |
|
|
612 | as to not disturb the other process. |
560 | - Update the kernel state with all outstanding changes. |
613 | - Update the kernel state with all outstanding changes. |
561 | - Update the "event loop time". |
614 | - Update the "event loop time" (ev_now ()). |
562 | - Calculate for how long to sleep or block, if at all |
615 | - Calculate for how long to sleep or block, if at all |
563 | (active idle watchers, EVLOOP_NONBLOCK or not having |
616 | (active idle watchers, EVLOOP_NONBLOCK or not having |
564 | any active watchers at all will result in not sleeping). |
617 | any active watchers at all will result in not sleeping). |
565 | - Sleep if the I/O and timer collect interval say so. |
618 | - Sleep if the I/O and timer collect interval say so. |
566 | - Block the process, waiting for any events. |
619 | - Block the process, waiting for any events. |
567 | - Queue all outstanding I/O (fd) events. |
620 | - Queue all outstanding I/O (fd) events. |
568 | - Update the "event loop time" and do time jump handling. |
621 | - Update the "event loop time" (ev_now ()), and do time jump adjustments. |
569 | - Queue all outstanding timers. |
622 | - Queue all outstanding timers. |
570 | - Queue all outstanding periodics. |
623 | - Queue all outstanding periodics. |
571 | - If no events are pending now, queue all idle watchers. |
624 | - Unless any events are pending now, queue all idle watchers. |
572 | - Queue all check watchers. |
625 | - Queue all check watchers. |
573 | - Call all queued watchers in reverse order (i.e. check watchers first). |
626 | - Call all queued watchers in reverse order (i.e. check watchers first). |
574 | Signals and child watchers are implemented as I/O watchers, and will |
627 | Signals and child watchers are implemented as I/O watchers, and will |
575 | be handled here by queueing them when their watcher gets executed. |
628 | be handled here by queueing them when their watcher gets executed. |
576 | - If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
629 | - If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
… | |
… | |
581 | anymore. |
634 | anymore. |
582 | |
635 | |
583 | ... queue jobs here, make sure they register event watchers as long |
636 | ... queue jobs here, make sure they register event watchers as long |
584 | ... as they still have work to do (even an idle watcher will do..) |
637 | ... as they still have work to do (even an idle watcher will do..) |
585 | ev_loop (my_loop, 0); |
638 | ev_loop (my_loop, 0); |
586 | ... jobs done. yeah! |
639 | ... jobs done or somebody called unloop. yeah! |
587 | |
640 | |
588 | =item ev_unloop (loop, how) |
641 | =item ev_unloop (loop, how) |
589 | |
642 | |
590 | Can be used to make a call to C<ev_loop> return early (but only after it |
643 | Can be used to make a call to C<ev_loop> return early (but only after it |
591 | has processed all outstanding events). The C<how> argument must be either |
644 | has processed all outstanding events). The C<how> argument must be either |
… | |
… | |
605 | returning, ev_unref() after starting, and ev_ref() before stopping it. For |
658 | returning, ev_unref() after starting, and ev_ref() before stopping it. For |
606 | example, libev itself uses this for its internal signal pipe: It is not |
659 | example, libev itself uses this for its internal signal pipe: It is not |
607 | visible to the libev user and should not keep C<ev_loop> from exiting if |
660 | visible to the libev user and should not keep C<ev_loop> from exiting if |
608 | no event watchers registered by it are active. It is also an excellent |
661 | no event watchers registered by it are active. It is also an excellent |
609 | way to do this for generic recurring timers or from within third-party |
662 | way to do this for generic recurring timers or from within third-party |
610 | libraries. Just remember to I<unref after start> and I<ref before stop>. |
663 | libraries. Just remember to I<unref after start> and I<ref before stop> |
|
|
664 | (but only if the watcher wasn't active before, or was active before, |
|
|
665 | respectively). |
611 | |
666 | |
612 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
667 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
613 | running when nothing else is active. |
668 | running when nothing else is active. |
614 | |
669 | |
615 | struct ev_signal exitsig; |
670 | struct ev_signal exitsig; |
616 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
671 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
617 | ev_signal_start (loop, &exitsig); |
672 | ev_signal_start (loop, &exitsig); |
618 | evf_unref (loop); |
673 | evf_unref (loop); |
619 | |
674 | |
620 | Example: For some weird reason, unregister the above signal handler again. |
675 | Example: For some weird reason, unregister the above signal handler again. |
621 | |
676 | |
622 | ev_ref (loop); |
677 | ev_ref (loop); |
623 | ev_signal_stop (loop, &exitsig); |
678 | ev_signal_stop (loop, &exitsig); |
624 | |
679 | |
625 | =item ev_set_io_collect_interval (loop, ev_tstamp interval) |
680 | =item ev_set_io_collect_interval (loop, ev_tstamp interval) |
626 | |
681 | |
627 | =item ev_set_timeout_collect_interval (loop, ev_tstamp interval) |
682 | =item ev_set_timeout_collect_interval (loop, ev_tstamp interval) |
628 | |
683 | |
629 | These advanced functions influence the time that libev will spend waiting |
684 | These advanced functions influence the time that libev will spend waiting |
630 | for events. Both are by default C<0>, meaning that libev will try to |
685 | for events. Both time intervals are by default C<0>, meaning that libev |
631 | invoke timer/periodic callbacks and I/O callbacks with minimum latency. |
686 | will try to invoke timer/periodic callbacks and I/O callbacks with minimum |
|
|
687 | latency. |
632 | |
688 | |
633 | Setting these to a higher value (the C<interval> I<must> be >= C<0>) |
689 | Setting these to a higher value (the C<interval> I<must> be >= C<0>) |
634 | allows libev to delay invocation of I/O and timer/periodic callbacks to |
690 | allows libev to delay invocation of I/O and timer/periodic callbacks |
635 | increase efficiency of loop iterations. |
691 | to increase efficiency of loop iterations (or to increase power-saving |
|
|
692 | opportunities). |
636 | |
693 | |
637 | The background is that sometimes your program runs just fast enough to |
694 | The background is that sometimes your program runs just fast enough to |
638 | handle one (or very few) event(s) per loop iteration. While this makes |
695 | handle one (or very few) event(s) per loop iteration. While this makes |
639 | the program responsive, it also wastes a lot of CPU time to poll for new |
696 | the program responsive, it also wastes a lot of CPU time to poll for new |
640 | events, especially with backends like C<select ()> which have a high |
697 | events, especially with backends like C<select ()> which have a high |
… | |
… | |
650 | to spend more time collecting timeouts, at the expense of increased |
707 | to spend more time collecting timeouts, at the expense of increased |
651 | latency (the watcher callback will be called later). C<ev_io> watchers |
708 | latency (the watcher callback will be called later). C<ev_io> watchers |
652 | will not be affected. Setting this to a non-null value will not introduce |
709 | will not be affected. Setting this to a non-null value will not introduce |
653 | any overhead in libev. |
710 | any overhead in libev. |
654 | |
711 | |
655 | Many (busy) programs can usually benefit by setting the io collect |
712 | Many (busy) programs can usually benefit by setting the I/O collect |
656 | interval to a value near C<0.1> or so, which is often enough for |
713 | interval to a value near C<0.1> or so, which is often enough for |
657 | interactive servers (of course not for games), likewise for timeouts. It |
714 | interactive servers (of course not for games), likewise for timeouts. It |
658 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
715 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
659 | as this approsaches the timing granularity of most systems. |
716 | as this approaches the timing granularity of most systems. |
|
|
717 | |
|
|
718 | Setting the I<timeout collect interval> can improve the opportunity for |
|
|
719 | saving power, as the program will "bundle" timer callback invocations that |
|
|
720 | are "near" in time together, by delaying some, thus reducing the number of |
|
|
721 | times the process sleeps and wakes up again. Another useful technique to |
|
|
722 | reduce iterations/wake-ups is to use C<ev_periodic> watchers and make sure |
|
|
723 | they fire on, say, one-second boundaries only. |
|
|
724 | |
|
|
725 | =item ev_loop_verify (loop) |
|
|
726 | |
|
|
727 | This function only does something when C<EV_VERIFY> support has been |
|
|
728 | compiled in. It tries to go through all internal structures and checks |
|
|
729 | them for validity. If anything is found to be inconsistent, it will print |
|
|
730 | an error message to standard error and call C<abort ()>. |
|
|
731 | |
|
|
732 | This can be used to catch bugs inside libev itself: under normal |
|
|
733 | circumstances, this function will never abort as of course libev keeps its |
|
|
734 | data structures consistent. |
660 | |
735 | |
661 | =back |
736 | =back |
662 | |
737 | |
663 | |
738 | |
664 | =head1 ANATOMY OF A WATCHER |
739 | =head1 ANATOMY OF A WATCHER |
665 | |
740 | |
666 | A watcher is a structure that you create and register to record your |
741 | A watcher is a structure that you create and register to record your |
667 | interest in some event. For instance, if you want to wait for STDIN to |
742 | interest in some event. For instance, if you want to wait for STDIN to |
668 | become readable, you would create an C<ev_io> watcher for that: |
743 | become readable, you would create an C<ev_io> watcher for that: |
669 | |
744 | |
670 | static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
745 | static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
671 | { |
746 | { |
672 | ev_io_stop (w); |
747 | ev_io_stop (w); |
673 | ev_unloop (loop, EVUNLOOP_ALL); |
748 | ev_unloop (loop, EVUNLOOP_ALL); |
674 | } |
749 | } |
675 | |
750 | |
676 | struct ev_loop *loop = ev_default_loop (0); |
751 | struct ev_loop *loop = ev_default_loop (0); |
677 | struct ev_io stdin_watcher; |
752 | struct ev_io stdin_watcher; |
678 | ev_init (&stdin_watcher, my_cb); |
753 | ev_init (&stdin_watcher, my_cb); |
679 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
754 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
680 | ev_io_start (loop, &stdin_watcher); |
755 | ev_io_start (loop, &stdin_watcher); |
681 | ev_loop (loop, 0); |
756 | ev_loop (loop, 0); |
682 | |
757 | |
683 | As you can see, you are responsible for allocating the memory for your |
758 | As you can see, you are responsible for allocating the memory for your |
684 | watcher structures (and it is usually a bad idea to do this on the stack, |
759 | watcher structures (and it is usually a bad idea to do this on the stack, |
685 | although this can sometimes be quite valid). |
760 | although this can sometimes be quite valid). |
686 | |
761 | |
687 | Each watcher structure must be initialised by a call to C<ev_init |
762 | Each watcher structure must be initialised by a call to C<ev_init |
688 | (watcher *, callback)>, which expects a callback to be provided. This |
763 | (watcher *, callback)>, which expects a callback to be provided. This |
689 | callback gets invoked each time the event occurs (or, in the case of io |
764 | callback gets invoked each time the event occurs (or, in the case of I/O |
690 | watchers, each time the event loop detects that the file descriptor given |
765 | watchers, each time the event loop detects that the file descriptor given |
691 | is readable and/or writable). |
766 | is readable and/or writable). |
692 | |
767 | |
693 | Each watcher type has its own C<< ev_<type>_set (watcher *, ...) >> macro |
768 | Each watcher type has its own C<< ev_<type>_set (watcher *, ...) >> macro |
694 | with arguments specific to this watcher type. There is also a macro |
769 | with arguments specific to this watcher type. There is also a macro |
… | |
… | |
764 | =item C<EV_FORK> |
839 | =item C<EV_FORK> |
765 | |
840 | |
766 | The event loop has been resumed in the child process after fork (see |
841 | The event loop has been resumed in the child process after fork (see |
767 | C<ev_fork>). |
842 | C<ev_fork>). |
768 | |
843 | |
|
|
844 | =item C<EV_ASYNC> |
|
|
845 | |
|
|
846 | The given async watcher has been asynchronously notified (see C<ev_async>). |
|
|
847 | |
769 | =item C<EV_ERROR> |
848 | =item C<EV_ERROR> |
770 | |
849 | |
771 | An unspecified error has occured, the watcher has been stopped. This might |
850 | An unspecified error has occurred, the watcher has been stopped. This might |
772 | happen because the watcher could not be properly started because libev |
851 | happen because the watcher could not be properly started because libev |
773 | ran out of memory, a file descriptor was found to be closed or any other |
852 | ran out of memory, a file descriptor was found to be closed or any other |
774 | problem. You best act on it by reporting the problem and somehow coping |
853 | problem. You best act on it by reporting the problem and somehow coping |
775 | with the watcher being stopped. |
854 | with the watcher being stopped. |
776 | |
855 | |
777 | Libev will usually signal a few "dummy" events together with an error, |
856 | Libev will usually signal a few "dummy" events together with an error, |
778 | for example it might indicate that a fd is readable or writable, and if |
857 | for example it might indicate that a fd is readable or writable, and if |
779 | your callbacks is well-written it can just attempt the operation and cope |
858 | your callbacks is well-written it can just attempt the operation and cope |
780 | with the error from read() or write(). This will not work in multithreaded |
859 | with the error from read() or write(). This will not work in multi-threaded |
781 | programs, though, so beware. |
860 | programs, though, so beware. |
782 | |
861 | |
783 | =back |
862 | =back |
784 | |
863 | |
785 | =head2 GENERIC WATCHER FUNCTIONS |
864 | =head2 GENERIC WATCHER FUNCTIONS |
… | |
… | |
815 | Although some watcher types do not have type-specific arguments |
894 | Although some watcher types do not have type-specific arguments |
816 | (e.g. C<ev_prepare>) you still need to call its C<set> macro. |
895 | (e.g. C<ev_prepare>) you still need to call its C<set> macro. |
817 | |
896 | |
818 | =item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args]) |
897 | =item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args]) |
819 | |
898 | |
820 | This convinience macro rolls both C<ev_init> and C<ev_TYPE_set> macro |
899 | This convenience macro rolls both C<ev_init> and C<ev_TYPE_set> macro |
821 | calls into a single call. This is the most convinient method to initialise |
900 | calls into a single call. This is the most convenient method to initialise |
822 | a watcher. The same limitations apply, of course. |
901 | a watcher. The same limitations apply, of course. |
823 | |
902 | |
824 | =item C<ev_TYPE_start> (loop *, ev_TYPE *watcher) |
903 | =item C<ev_TYPE_start> (loop *, ev_TYPE *watcher) |
825 | |
904 | |
826 | Starts (activates) the given watcher. Only active watchers will receive |
905 | Starts (activates) the given watcher. Only active watchers will receive |
… | |
… | |
909 | to associate arbitrary data with your watcher. If you need more data and |
988 | to associate arbitrary data with your watcher. If you need more data and |
910 | don't want to allocate memory and store a pointer to it in that data |
989 | don't want to allocate memory and store a pointer to it in that data |
911 | member, you can also "subclass" the watcher type and provide your own |
990 | member, you can also "subclass" the watcher type and provide your own |
912 | data: |
991 | data: |
913 | |
992 | |
914 | struct my_io |
993 | struct my_io |
915 | { |
994 | { |
916 | struct ev_io io; |
995 | struct ev_io io; |
917 | int otherfd; |
996 | int otherfd; |
918 | void *somedata; |
997 | void *somedata; |
919 | struct whatever *mostinteresting; |
998 | struct whatever *mostinteresting; |
920 | } |
999 | } |
921 | |
1000 | |
922 | And since your callback will be called with a pointer to the watcher, you |
1001 | And since your callback will be called with a pointer to the watcher, you |
923 | can cast it back to your own type: |
1002 | can cast it back to your own type: |
924 | |
1003 | |
925 | static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents) |
1004 | static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents) |
926 | { |
1005 | { |
927 | struct my_io *w = (struct my_io *)w_; |
1006 | struct my_io *w = (struct my_io *)w_; |
928 | ... |
1007 | ... |
929 | } |
1008 | } |
930 | |
1009 | |
931 | More interesting and less C-conformant ways of casting your callback type |
1010 | More interesting and less C-conformant ways of casting your callback type |
932 | instead have been omitted. |
1011 | instead have been omitted. |
933 | |
1012 | |
934 | Another common scenario is having some data structure with multiple |
1013 | Another common scenario is having some data structure with multiple |
935 | watchers: |
1014 | watchers: |
936 | |
1015 | |
937 | struct my_biggy |
1016 | struct my_biggy |
938 | { |
1017 | { |
939 | int some_data; |
1018 | int some_data; |
940 | ev_timer t1; |
1019 | ev_timer t1; |
941 | ev_timer t2; |
1020 | ev_timer t2; |
942 | } |
1021 | } |
943 | |
1022 | |
944 | In this case getting the pointer to C<my_biggy> is a bit more complicated, |
1023 | In this case getting the pointer to C<my_biggy> is a bit more complicated, |
945 | you need to use C<offsetof>: |
1024 | you need to use C<offsetof>: |
946 | |
1025 | |
947 | #include <stddef.h> |
1026 | #include <stddef.h> |
948 | |
1027 | |
949 | static void |
1028 | static void |
950 | t1_cb (EV_P_ struct ev_timer *w, int revents) |
1029 | t1_cb (EV_P_ struct ev_timer *w, int revents) |
951 | { |
1030 | { |
952 | struct my_biggy big = (struct my_biggy * |
1031 | struct my_biggy big = (struct my_biggy * |
953 | (((char *)w) - offsetof (struct my_biggy, t1)); |
1032 | (((char *)w) - offsetof (struct my_biggy, t1)); |
954 | } |
1033 | } |
955 | |
1034 | |
956 | static void |
1035 | static void |
957 | t2_cb (EV_P_ struct ev_timer *w, int revents) |
1036 | t2_cb (EV_P_ struct ev_timer *w, int revents) |
958 | { |
1037 | { |
959 | struct my_biggy big = (struct my_biggy * |
1038 | struct my_biggy big = (struct my_biggy * |
960 | (((char *)w) - offsetof (struct my_biggy, t2)); |
1039 | (((char *)w) - offsetof (struct my_biggy, t2)); |
961 | } |
1040 | } |
962 | |
1041 | |
963 | |
1042 | |
964 | =head1 WATCHER TYPES |
1043 | =head1 WATCHER TYPES |
965 | |
1044 | |
966 | This section describes each watcher in detail, but will not repeat |
1045 | This section describes each watcher in detail, but will not repeat |
… | |
… | |
995 | If you must do this, then force the use of a known-to-be-good backend |
1074 | If you must do this, then force the use of a known-to-be-good backend |
996 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
1075 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
997 | C<EVBACKEND_POLL>). |
1076 | C<EVBACKEND_POLL>). |
998 | |
1077 | |
999 | Another thing you have to watch out for is that it is quite easy to |
1078 | Another thing you have to watch out for is that it is quite easy to |
1000 | receive "spurious" readyness notifications, that is your callback might |
1079 | receive "spurious" readiness notifications, that is your callback might |
1001 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1080 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1002 | because there is no data. Not only are some backends known to create a |
1081 | because there is no data. Not only are some backends known to create a |
1003 | lot of those (for example solaris ports), it is very easy to get into |
1082 | lot of those (for example Solaris ports), it is very easy to get into |
1004 | this situation even with a relatively standard program structure. Thus |
1083 | this situation even with a relatively standard program structure. Thus |
1005 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
1084 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
1006 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
1085 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
1007 | |
1086 | |
1008 | If you cannot run the fd in non-blocking mode (for example you should not |
1087 | If you cannot run the fd in non-blocking mode (for example you should not |
1009 | play around with an Xlib connection), then you have to seperately re-test |
1088 | play around with an Xlib connection), then you have to separately re-test |
1010 | whether a file descriptor is really ready with a known-to-be good interface |
1089 | whether a file descriptor is really ready with a known-to-be good interface |
1011 | such as poll (fortunately in our Xlib example, Xlib already does this on |
1090 | such as poll (fortunately in our Xlib example, Xlib already does this on |
1012 | its own, so its quite safe to use). |
1091 | its own, so its quite safe to use). |
1013 | |
1092 | |
1014 | =head3 The special problem of disappearing file descriptors |
1093 | =head3 The special problem of disappearing file descriptors |
… | |
… | |
1052 | To support fork in your programs, you either have to call |
1131 | To support fork in your programs, you either have to call |
1053 | C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child, |
1132 | C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child, |
1054 | enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or |
1133 | enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or |
1055 | C<EVBACKEND_POLL>. |
1134 | C<EVBACKEND_POLL>. |
1056 | |
1135 | |
|
|
1136 | =head3 The special problem of SIGPIPE |
|
|
1137 | |
|
|
1138 | While not really specific to libev, it is easy to forget about SIGPIPE: |
|
|
1139 | when writing to a pipe whose other end has been closed, your program gets |
|
|
1140 | send a SIGPIPE, which, by default, aborts your program. For most programs |
|
|
1141 | this is sensible behaviour, for daemons, this is usually undesirable. |
|
|
1142 | |
|
|
1143 | So when you encounter spurious, unexplained daemon exits, make sure you |
|
|
1144 | ignore SIGPIPE (and maybe make sure you log the exit status of your daemon |
|
|
1145 | somewhere, as that would have given you a big clue). |
|
|
1146 | |
1057 | |
1147 | |
1058 | =head3 Watcher-Specific Functions |
1148 | =head3 Watcher-Specific Functions |
1059 | |
1149 | |
1060 | =over 4 |
1150 | =over 4 |
1061 | |
1151 | |
1062 | =item ev_io_init (ev_io *, callback, int fd, int events) |
1152 | =item ev_io_init (ev_io *, callback, int fd, int events) |
1063 | |
1153 | |
1064 | =item ev_io_set (ev_io *, int fd, int events) |
1154 | =item ev_io_set (ev_io *, int fd, int events) |
1065 | |
1155 | |
1066 | Configures an C<ev_io> watcher. The C<fd> is the file descriptor to |
1156 | Configures an C<ev_io> watcher. The C<fd> is the file descriptor to |
1067 | rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or |
1157 | receive events for and events is either C<EV_READ>, C<EV_WRITE> or |
1068 | C<EV_READ | EV_WRITE> to receive the given events. |
1158 | C<EV_READ | EV_WRITE> to receive the given events. |
1069 | |
1159 | |
1070 | =item int fd [read-only] |
1160 | =item int fd [read-only] |
1071 | |
1161 | |
1072 | The file descriptor being watched. |
1162 | The file descriptor being watched. |
… | |
… | |
1081 | |
1171 | |
1082 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
1172 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
1083 | readable, but only once. Since it is likely line-buffered, you could |
1173 | readable, but only once. Since it is likely line-buffered, you could |
1084 | attempt to read a whole line in the callback. |
1174 | attempt to read a whole line in the callback. |
1085 | |
1175 | |
1086 | static void |
1176 | static void |
1087 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1177 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1088 | { |
1178 | { |
1089 | ev_io_stop (loop, w); |
1179 | ev_io_stop (loop, w); |
1090 | .. read from stdin here (or from w->fd) and haqndle any I/O errors |
1180 | .. read from stdin here (or from w->fd) and haqndle any I/O errors |
1091 | } |
1181 | } |
1092 | |
1182 | |
1093 | ... |
1183 | ... |
1094 | struct ev_loop *loop = ev_default_init (0); |
1184 | struct ev_loop *loop = ev_default_init (0); |
1095 | struct ev_io stdin_readable; |
1185 | struct ev_io stdin_readable; |
1096 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1186 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1097 | ev_io_start (loop, &stdin_readable); |
1187 | ev_io_start (loop, &stdin_readable); |
1098 | ev_loop (loop, 0); |
1188 | ev_loop (loop, 0); |
1099 | |
1189 | |
1100 | |
1190 | |
1101 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
1191 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
1102 | |
1192 | |
1103 | Timer watchers are simple relative timers that generate an event after a |
1193 | Timer watchers are simple relative timers that generate an event after a |
1104 | given time, and optionally repeating in regular intervals after that. |
1194 | given time, and optionally repeating in regular intervals after that. |
1105 | |
1195 | |
1106 | The timers are based on real time, that is, if you register an event that |
1196 | The timers are based on real time, that is, if you register an event that |
1107 | times out after an hour and you reset your system clock to last years |
1197 | times out after an hour and you reset your system clock to January last |
1108 | time, it will still time out after (roughly) and hour. "Roughly" because |
1198 | year, it will still time out after (roughly) and hour. "Roughly" because |
1109 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1199 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1110 | monotonic clock option helps a lot here). |
1200 | monotonic clock option helps a lot here). |
|
|
1201 | |
|
|
1202 | The callback is guaranteed to be invoked only after its timeout has passed, |
|
|
1203 | but if multiple timers become ready during the same loop iteration then |
|
|
1204 | order of execution is undefined. |
|
|
1205 | |
|
|
1206 | =head3 The special problem of time updates |
|
|
1207 | |
|
|
1208 | Requesting the current time is a costly operation (it usually takes at |
|
|
1209 | least two syscalls): EV therefore updates it's idea of the current time |
|
|
1210 | only before and after C<ev_loop> polls for new events, which causes the |
|
|
1211 | difference between C<ev_now ()> and C<ev_time ()>. |
1111 | |
1212 | |
1112 | The relative timeouts are calculated relative to the C<ev_now ()> |
1213 | The relative timeouts are calculated relative to the C<ev_now ()> |
1113 | time. This is usually the right thing as this timestamp refers to the time |
1214 | time. This is usually the right thing as this timestamp refers to the time |
1114 | of the event triggering whatever timeout you are modifying/starting. If |
1215 | of the event triggering whatever timeout you are modifying/starting. If |
1115 | you suspect event processing to be delayed and you I<need> to base the timeout |
1216 | you suspect event processing to be delayed and you I<need> to base the |
1116 | on the current time, use something like this to adjust for this: |
1217 | timeout on the current time, use something like this to adjust for this: |
1117 | |
1218 | |
1118 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
1219 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
1119 | |
1220 | |
1120 | The callback is guarenteed to be invoked only when its timeout has passed, |
|
|
1121 | but if multiple timers become ready during the same loop iteration then |
|
|
1122 | order of execution is undefined. |
|
|
1123 | |
|
|
1124 | =head3 Watcher-Specific Functions and Data Members |
1221 | =head3 Watcher-Specific Functions and Data Members |
1125 | |
1222 | |
1126 | =over 4 |
1223 | =over 4 |
1127 | |
1224 | |
1128 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
1225 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
1129 | |
1226 | |
1130 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
1227 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
1131 | |
1228 | |
1132 | Configure the timer to trigger after C<after> seconds. If C<repeat> is |
1229 | Configure the timer to trigger after C<after> seconds. If C<repeat> |
1133 | C<0.>, then it will automatically be stopped. If it is positive, then the |
1230 | is C<0.>, then it will automatically be stopped once the timeout is |
1134 | timer will automatically be configured to trigger again C<repeat> seconds |
1231 | reached. If it is positive, then the timer will automatically be |
1135 | later, again, and again, until stopped manually. |
1232 | configured to trigger again C<repeat> seconds later, again, and again, |
|
|
1233 | until stopped manually. |
1136 | |
1234 | |
1137 | The timer itself will do a best-effort at avoiding drift, that is, if you |
1235 | The timer itself will do a best-effort at avoiding drift, that is, if |
1138 | configure a timer to trigger every 10 seconds, then it will trigger at |
1236 | you configure a timer to trigger every 10 seconds, then it will normally |
1139 | exactly 10 second intervals. If, however, your program cannot keep up with |
1237 | trigger at exactly 10 second intervals. If, however, your program cannot |
1140 | the timer (because it takes longer than those 10 seconds to do stuff) the |
1238 | keep up with the timer (because it takes longer than those 10 seconds to |
1141 | timer will not fire more than once per event loop iteration. |
1239 | do stuff) the timer will not fire more than once per event loop iteration. |
1142 | |
1240 | |
1143 | =item ev_timer_again (loop) |
1241 | =item ev_timer_again (loop, ev_timer *) |
1144 | |
1242 | |
1145 | This will act as if the timer timed out and restart it again if it is |
1243 | This will act as if the timer timed out and restart it again if it is |
1146 | repeating. The exact semantics are: |
1244 | repeating. The exact semantics are: |
1147 | |
1245 | |
1148 | If the timer is pending, its pending status is cleared. |
1246 | If the timer is pending, its pending status is cleared. |
1149 | |
1247 | |
1150 | If the timer is started but nonrepeating, stop it (as if it timed out). |
1248 | If the timer is started but non-repeating, stop it (as if it timed out). |
1151 | |
1249 | |
1152 | If the timer is repeating, either start it if necessary (with the |
1250 | If the timer is repeating, either start it if necessary (with the |
1153 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1251 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1154 | |
1252 | |
1155 | This sounds a bit complicated, but here is a useful and typical |
1253 | This sounds a bit complicated, but here is a useful and typical |
1156 | example: Imagine you have a tcp connection and you want a so-called idle |
1254 | example: Imagine you have a TCP connection and you want a so-called idle |
1157 | timeout, that is, you want to be called when there have been, say, 60 |
1255 | timeout, that is, you want to be called when there have been, say, 60 |
1158 | seconds of inactivity on the socket. The easiest way to do this is to |
1256 | seconds of inactivity on the socket. The easiest way to do this is to |
1159 | configure an C<ev_timer> with a C<repeat> value of C<60> and then call |
1257 | configure an C<ev_timer> with a C<repeat> value of C<60> and then call |
1160 | C<ev_timer_again> each time you successfully read or write some data. If |
1258 | C<ev_timer_again> each time you successfully read or write some data. If |
1161 | you go into an idle state where you do not expect data to travel on the |
1259 | you go into an idle state where you do not expect data to travel on the |
… | |
… | |
1187 | |
1285 | |
1188 | =head3 Examples |
1286 | =head3 Examples |
1189 | |
1287 | |
1190 | Example: Create a timer that fires after 60 seconds. |
1288 | Example: Create a timer that fires after 60 seconds. |
1191 | |
1289 | |
1192 | static void |
1290 | static void |
1193 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1291 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1194 | { |
1292 | { |
1195 | .. one minute over, w is actually stopped right here |
1293 | .. one minute over, w is actually stopped right here |
1196 | } |
1294 | } |
1197 | |
1295 | |
1198 | struct ev_timer mytimer; |
1296 | struct ev_timer mytimer; |
1199 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
1297 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
1200 | ev_timer_start (loop, &mytimer); |
1298 | ev_timer_start (loop, &mytimer); |
1201 | |
1299 | |
1202 | Example: Create a timeout timer that times out after 10 seconds of |
1300 | Example: Create a timeout timer that times out after 10 seconds of |
1203 | inactivity. |
1301 | inactivity. |
1204 | |
1302 | |
1205 | static void |
1303 | static void |
1206 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1304 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1207 | { |
1305 | { |
1208 | .. ten seconds without any activity |
1306 | .. ten seconds without any activity |
1209 | } |
1307 | } |
1210 | |
1308 | |
1211 | struct ev_timer mytimer; |
1309 | struct ev_timer mytimer; |
1212 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1310 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1213 | ev_timer_again (&mytimer); /* start timer */ |
1311 | ev_timer_again (&mytimer); /* start timer */ |
1214 | ev_loop (loop, 0); |
1312 | ev_loop (loop, 0); |
1215 | |
1313 | |
1216 | // and in some piece of code that gets executed on any "activity": |
1314 | // and in some piece of code that gets executed on any "activity": |
1217 | // reset the timeout to start ticking again at 10 seconds |
1315 | // reset the timeout to start ticking again at 10 seconds |
1218 | ev_timer_again (&mytimer); |
1316 | ev_timer_again (&mytimer); |
1219 | |
1317 | |
1220 | |
1318 | |
1221 | =head2 C<ev_periodic> - to cron or not to cron? |
1319 | =head2 C<ev_periodic> - to cron or not to cron? |
1222 | |
1320 | |
1223 | Periodic watchers are also timers of a kind, but they are very versatile |
1321 | Periodic watchers are also timers of a kind, but they are very versatile |
1224 | (and unfortunately a bit complex). |
1322 | (and unfortunately a bit complex). |
1225 | |
1323 | |
1226 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
1324 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
1227 | but on wallclock time (absolute time). You can tell a periodic watcher |
1325 | but on wall clock time (absolute time). You can tell a periodic watcher |
1228 | to trigger "at" some specific point in time. For example, if you tell a |
1326 | to trigger after some specific point in time. For example, if you tell a |
1229 | periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now () |
1327 | periodic watcher to trigger in 10 seconds (by specifying e.g. C<ev_now () |
1230 | + 10.>) and then reset your system clock to the last year, then it will |
1328 | + 10.>, that is, an absolute time not a delay) and then reset your system |
|
|
1329 | clock to January of the previous year, then it will take more than year |
1231 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
1330 | to trigger the event (unlike an C<ev_timer>, which would still trigger |
1232 | roughly 10 seconds later). |
1331 | roughly 10 seconds later as it uses a relative timeout). |
1233 | |
1332 | |
1234 | They can also be used to implement vastly more complex timers, such as |
1333 | C<ev_periodic>s can also be used to implement vastly more complex timers, |
1235 | triggering an event on each midnight, local time or other, complicated, |
1334 | such as triggering an event on each "midnight, local time", or other |
1236 | rules. |
1335 | complicated, rules. |
1237 | |
1336 | |
1238 | As with timers, the callback is guarenteed to be invoked only when the |
1337 | As with timers, the callback is guaranteed to be invoked only when the |
1239 | time (C<at>) has been passed, but if multiple periodic timers become ready |
1338 | time (C<at>) has passed, but if multiple periodic timers become ready |
1240 | during the same loop iteration then order of execution is undefined. |
1339 | during the same loop iteration then order of execution is undefined. |
1241 | |
1340 | |
1242 | =head3 Watcher-Specific Functions and Data Members |
1341 | =head3 Watcher-Specific Functions and Data Members |
1243 | |
1342 | |
1244 | =over 4 |
1343 | =over 4 |
… | |
… | |
1252 | |
1351 | |
1253 | =over 4 |
1352 | =over 4 |
1254 | |
1353 | |
1255 | =item * absolute timer (at = time, interval = reschedule_cb = 0) |
1354 | =item * absolute timer (at = time, interval = reschedule_cb = 0) |
1256 | |
1355 | |
1257 | In this configuration the watcher triggers an event at the wallclock time |
1356 | In this configuration the watcher triggers an event after the wall clock |
1258 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
1357 | time C<at> has passed and doesn't repeat. It will not adjust when a time |
1259 | that is, if it is to be run at January 1st 2011 then it will run when the |
1358 | jump occurs, that is, if it is to be run at January 1st 2011 then it will |
1260 | system time reaches or surpasses this time. |
1359 | run when the system time reaches or surpasses this time. |
1261 | |
1360 | |
1262 | =item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
1361 | =item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
1263 | |
1362 | |
1264 | In this mode the watcher will always be scheduled to time out at the next |
1363 | In this mode the watcher will always be scheduled to time out at the next |
1265 | C<at + N * interval> time (for some integer N, which can also be negative) |
1364 | C<at + N * interval> time (for some integer N, which can also be negative) |
1266 | and then repeat, regardless of any time jumps. |
1365 | and then repeat, regardless of any time jumps. |
1267 | |
1366 | |
1268 | This can be used to create timers that do not drift with respect to system |
1367 | This can be used to create timers that do not drift with respect to system |
1269 | time: |
1368 | time, for example, here is a C<ev_periodic> that triggers each hour, on |
|
|
1369 | the hour: |
1270 | |
1370 | |
1271 | ev_periodic_set (&periodic, 0., 3600., 0); |
1371 | ev_periodic_set (&periodic, 0., 3600., 0); |
1272 | |
1372 | |
1273 | This doesn't mean there will always be 3600 seconds in between triggers, |
1373 | This doesn't mean there will always be 3600 seconds in between triggers, |
1274 | but only that the the callback will be called when the system time shows a |
1374 | but only that the callback will be called when the system time shows a |
1275 | full hour (UTC), or more correctly, when the system time is evenly divisible |
1375 | full hour (UTC), or more correctly, when the system time is evenly divisible |
1276 | by 3600. |
1376 | by 3600. |
1277 | |
1377 | |
1278 | Another way to think about it (for the mathematically inclined) is that |
1378 | Another way to think about it (for the mathematically inclined) is that |
1279 | C<ev_periodic> will try to run the callback in this mode at the next possible |
1379 | C<ev_periodic> will try to run the callback in this mode at the next possible |
1280 | time where C<time = at (mod interval)>, regardless of any time jumps. |
1380 | time where C<time = at (mod interval)>, regardless of any time jumps. |
1281 | |
1381 | |
1282 | For numerical stability it is preferable that the C<at> value is near |
1382 | For numerical stability it is preferable that the C<at> value is near |
1283 | C<ev_now ()> (the current time), but there is no range requirement for |
1383 | C<ev_now ()> (the current time), but there is no range requirement for |
1284 | this value. |
1384 | this value, and in fact is often specified as zero. |
|
|
1385 | |
|
|
1386 | Note also that there is an upper limit to how often a timer can fire (CPU |
|
|
1387 | speed for example), so if C<interval> is very small then timing stability |
|
|
1388 | will of course deteriorate. Libev itself tries to be exact to be about one |
|
|
1389 | millisecond (if the OS supports it and the machine is fast enough). |
1285 | |
1390 | |
1286 | =item * manual reschedule mode (at and interval ignored, reschedule_cb = callback) |
1391 | =item * manual reschedule mode (at and interval ignored, reschedule_cb = callback) |
1287 | |
1392 | |
1288 | In this mode the values for C<interval> and C<at> are both being |
1393 | In this mode the values for C<interval> and C<at> are both being |
1289 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1394 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1290 | reschedule callback will be called with the watcher as first, and the |
1395 | reschedule callback will be called with the watcher as first, and the |
1291 | current time as second argument. |
1396 | current time as second argument. |
1292 | |
1397 | |
1293 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
1398 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
1294 | ever, or make any event loop modifications>. If you need to stop it, |
1399 | ever, or make ANY event loop modifications whatsoever>. |
1295 | return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by |
|
|
1296 | starting an C<ev_prepare> watcher, which is legal). |
|
|
1297 | |
1400 | |
|
|
1401 | If you need to stop it, return C<now + 1e30> (or so, fudge fudge) and stop |
|
|
1402 | it afterwards (e.g. by starting an C<ev_prepare> watcher, which is the |
|
|
1403 | only event loop modification you are allowed to do). |
|
|
1404 | |
1298 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1405 | The callback prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic |
1299 | ev_tstamp now)>, e.g.: |
1406 | *w, ev_tstamp now)>, e.g.: |
1300 | |
1407 | |
1301 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
1408 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
1302 | { |
1409 | { |
1303 | return now + 60.; |
1410 | return now + 60.; |
1304 | } |
1411 | } |
… | |
… | |
1306 | It must return the next time to trigger, based on the passed time value |
1413 | It must return the next time to trigger, based on the passed time value |
1307 | (that is, the lowest time value larger than to the second argument). It |
1414 | (that is, the lowest time value larger than to the second argument). It |
1308 | will usually be called just before the callback will be triggered, but |
1415 | will usually be called just before the callback will be triggered, but |
1309 | might be called at other times, too. |
1416 | might be called at other times, too. |
1310 | |
1417 | |
1311 | NOTE: I<< This callback must always return a time that is later than the |
1418 | NOTE: I<< This callback must always return a time that is higher than or |
1312 | passed C<now> value >>. Not even C<now> itself will do, it I<must> be larger. |
1419 | equal to the passed C<now> value >>. |
1313 | |
1420 | |
1314 | This can be used to create very complex timers, such as a timer that |
1421 | This can be used to create very complex timers, such as a timer that |
1315 | triggers on each midnight, local time. To do this, you would calculate the |
1422 | triggers on "next midnight, local time". To do this, you would calculate the |
1316 | next midnight after C<now> and return the timestamp value for this. How |
1423 | next midnight after C<now> and return the timestamp value for this. How |
1317 | you do this is, again, up to you (but it is not trivial, which is the main |
1424 | you do this is, again, up to you (but it is not trivial, which is the main |
1318 | reason I omitted it as an example). |
1425 | reason I omitted it as an example). |
1319 | |
1426 | |
1320 | =back |
1427 | =back |
… | |
… | |
1324 | Simply stops and restarts the periodic watcher again. This is only useful |
1431 | Simply stops and restarts the periodic watcher again. This is only useful |
1325 | when you changed some parameters or the reschedule callback would return |
1432 | when you changed some parameters or the reschedule callback would return |
1326 | a different time than the last time it was called (e.g. in a crond like |
1433 | a different time than the last time it was called (e.g. in a crond like |
1327 | program when the crontabs have changed). |
1434 | program when the crontabs have changed). |
1328 | |
1435 | |
|
|
1436 | =item ev_tstamp ev_periodic_at (ev_periodic *) |
|
|
1437 | |
|
|
1438 | When active, returns the absolute time that the watcher is supposed to |
|
|
1439 | trigger next. |
|
|
1440 | |
1329 | =item ev_tstamp offset [read-write] |
1441 | =item ev_tstamp offset [read-write] |
1330 | |
1442 | |
1331 | When repeating, this contains the offset value, otherwise this is the |
1443 | When repeating, this contains the offset value, otherwise this is the |
1332 | absolute point in time (the C<at> value passed to C<ev_periodic_set>). |
1444 | absolute point in time (the C<at> value passed to C<ev_periodic_set>). |
1333 | |
1445 | |
… | |
… | |
1344 | |
1456 | |
1345 | The current reschedule callback, or C<0>, if this functionality is |
1457 | The current reschedule callback, or C<0>, if this functionality is |
1346 | switched off. Can be changed any time, but changes only take effect when |
1458 | switched off. Can be changed any time, but changes only take effect when |
1347 | the periodic timer fires or C<ev_periodic_again> is being called. |
1459 | the periodic timer fires or C<ev_periodic_again> is being called. |
1348 | |
1460 | |
1349 | =item ev_tstamp at [read-only] |
|
|
1350 | |
|
|
1351 | When active, contains the absolute time that the watcher is supposed to |
|
|
1352 | trigger next. |
|
|
1353 | |
|
|
1354 | =back |
1461 | =back |
1355 | |
1462 | |
1356 | =head3 Examples |
1463 | =head3 Examples |
1357 | |
1464 | |
1358 | Example: Call a callback every hour, or, more precisely, whenever the |
1465 | Example: Call a callback every hour, or, more precisely, whenever the |
1359 | system clock is divisible by 3600. The callback invocation times have |
1466 | system clock is divisible by 3600. The callback invocation times have |
1360 | potentially a lot of jittering, but good long-term stability. |
1467 | potentially a lot of jitter, but good long-term stability. |
1361 | |
1468 | |
1362 | static void |
1469 | static void |
1363 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1470 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1364 | { |
1471 | { |
1365 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
1472 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
1366 | } |
1473 | } |
1367 | |
1474 | |
1368 | struct ev_periodic hourly_tick; |
1475 | struct ev_periodic hourly_tick; |
1369 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1476 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1370 | ev_periodic_start (loop, &hourly_tick); |
1477 | ev_periodic_start (loop, &hourly_tick); |
1371 | |
1478 | |
1372 | Example: The same as above, but use a reschedule callback to do it: |
1479 | Example: The same as above, but use a reschedule callback to do it: |
1373 | |
1480 | |
1374 | #include <math.h> |
1481 | #include <math.h> |
1375 | |
1482 | |
1376 | static ev_tstamp |
1483 | static ev_tstamp |
1377 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
1484 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
1378 | { |
1485 | { |
1379 | return fmod (now, 3600.) + 3600.; |
1486 | return fmod (now, 3600.) + 3600.; |
1380 | } |
1487 | } |
1381 | |
1488 | |
1382 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1489 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1383 | |
1490 | |
1384 | Example: Call a callback every hour, starting now: |
1491 | Example: Call a callback every hour, starting now: |
1385 | |
1492 | |
1386 | struct ev_periodic hourly_tick; |
1493 | struct ev_periodic hourly_tick; |
1387 | ev_periodic_init (&hourly_tick, clock_cb, |
1494 | ev_periodic_init (&hourly_tick, clock_cb, |
1388 | fmod (ev_now (loop), 3600.), 3600., 0); |
1495 | fmod (ev_now (loop), 3600.), 3600., 0); |
1389 | ev_periodic_start (loop, &hourly_tick); |
1496 | ev_periodic_start (loop, &hourly_tick); |
1390 | |
1497 | |
1391 | |
1498 | |
1392 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
1499 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
1393 | |
1500 | |
1394 | Signal watchers will trigger an event when the process receives a specific |
1501 | Signal watchers will trigger an event when the process receives a specific |
… | |
… | |
1401 | with the kernel (thus it coexists with your own signal handlers as long |
1508 | with the kernel (thus it coexists with your own signal handlers as long |
1402 | as you don't register any with libev). Similarly, when the last signal |
1509 | as you don't register any with libev). Similarly, when the last signal |
1403 | watcher for a signal is stopped libev will reset the signal handler to |
1510 | watcher for a signal is stopped libev will reset the signal handler to |
1404 | SIG_DFL (regardless of what it was set to before). |
1511 | SIG_DFL (regardless of what it was set to before). |
1405 | |
1512 | |
|
|
1513 | If possible and supported, libev will install its handlers with |
|
|
1514 | C<SA_RESTART> behaviour enabled, so system calls should not be unduly |
|
|
1515 | interrupted. If you have a problem with system calls getting interrupted by |
|
|
1516 | signals you can block all signals in an C<ev_check> watcher and unblock |
|
|
1517 | them in an C<ev_prepare> watcher. |
|
|
1518 | |
1406 | =head3 Watcher-Specific Functions and Data Members |
1519 | =head3 Watcher-Specific Functions and Data Members |
1407 | |
1520 | |
1408 | =over 4 |
1521 | =over 4 |
1409 | |
1522 | |
1410 | =item ev_signal_init (ev_signal *, callback, int signum) |
1523 | =item ev_signal_init (ev_signal *, callback, int signum) |
… | |
… | |
1418 | |
1531 | |
1419 | The signal the watcher watches out for. |
1532 | The signal the watcher watches out for. |
1420 | |
1533 | |
1421 | =back |
1534 | =back |
1422 | |
1535 | |
|
|
1536 | =head3 Examples |
|
|
1537 | |
|
|
1538 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
|
|
1539 | |
|
|
1540 | static void |
|
|
1541 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
|
|
1542 | { |
|
|
1543 | ev_unloop (loop, EVUNLOOP_ALL); |
|
|
1544 | } |
|
|
1545 | |
|
|
1546 | struct ev_signal signal_watcher; |
|
|
1547 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
|
|
1548 | ev_signal_start (loop, &sigint_cb); |
|
|
1549 | |
1423 | |
1550 | |
1424 | =head2 C<ev_child> - watch out for process status changes |
1551 | =head2 C<ev_child> - watch out for process status changes |
1425 | |
1552 | |
1426 | Child watchers trigger when your process receives a SIGCHLD in response to |
1553 | Child watchers trigger when your process receives a SIGCHLD in response to |
1427 | some child status changes (most typically when a child of yours dies). |
1554 | some child status changes (most typically when a child of yours dies). It |
|
|
1555 | is permissible to install a child watcher I<after> the child has been |
|
|
1556 | forked (which implies it might have already exited), as long as the event |
|
|
1557 | loop isn't entered (or is continued from a watcher). |
|
|
1558 | |
|
|
1559 | Only the default event loop is capable of handling signals, and therefore |
|
|
1560 | you can only register child watchers in the default event loop. |
|
|
1561 | |
|
|
1562 | =head3 Process Interaction |
|
|
1563 | |
|
|
1564 | Libev grabs C<SIGCHLD> as soon as the default event loop is |
|
|
1565 | initialised. This is necessary to guarantee proper behaviour even if |
|
|
1566 | the first child watcher is started after the child exits. The occurrence |
|
|
1567 | of C<SIGCHLD> is recorded asynchronously, but child reaping is done |
|
|
1568 | synchronously as part of the event loop processing. Libev always reaps all |
|
|
1569 | children, even ones not watched. |
|
|
1570 | |
|
|
1571 | =head3 Overriding the Built-In Processing |
|
|
1572 | |
|
|
1573 | Libev offers no special support for overriding the built-in child |
|
|
1574 | processing, but if your application collides with libev's default child |
|
|
1575 | handler, you can override it easily by installing your own handler for |
|
|
1576 | C<SIGCHLD> after initialising the default loop, and making sure the |
|
|
1577 | default loop never gets destroyed. You are encouraged, however, to use an |
|
|
1578 | event-based approach to child reaping and thus use libev's support for |
|
|
1579 | that, so other libev users can use C<ev_child> watchers freely. |
|
|
1580 | |
|
|
1581 | =head3 Stopping the Child Watcher |
|
|
1582 | |
|
|
1583 | Currently, the child watcher never gets stopped, even when the |
|
|
1584 | child terminates, so normally one needs to stop the watcher in the |
|
|
1585 | callback. Future versions of libev might stop the watcher automatically |
|
|
1586 | when a child exit is detected. |
1428 | |
1587 | |
1429 | =head3 Watcher-Specific Functions and Data Members |
1588 | =head3 Watcher-Specific Functions and Data Members |
1430 | |
1589 | |
1431 | =over 4 |
1590 | =over 4 |
1432 | |
1591 | |
1433 | =item ev_child_init (ev_child *, callback, int pid) |
1592 | =item ev_child_init (ev_child *, callback, int pid, int trace) |
1434 | |
1593 | |
1435 | =item ev_child_set (ev_child *, int pid) |
1594 | =item ev_child_set (ev_child *, int pid, int trace) |
1436 | |
1595 | |
1437 | Configures the watcher to wait for status changes of process C<pid> (or |
1596 | Configures the watcher to wait for status changes of process C<pid> (or |
1438 | I<any> process if C<pid> is specified as C<0>). The callback can look |
1597 | I<any> process if C<pid> is specified as C<0>). The callback can look |
1439 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
1598 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
1440 | the status word (use the macros from C<sys/wait.h> and see your systems |
1599 | the status word (use the macros from C<sys/wait.h> and see your systems |
1441 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
1600 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
1442 | process causing the status change. |
1601 | process causing the status change. C<trace> must be either C<0> (only |
|
|
1602 | activate the watcher when the process terminates) or C<1> (additionally |
|
|
1603 | activate the watcher when the process is stopped or continued). |
1443 | |
1604 | |
1444 | =item int pid [read-only] |
1605 | =item int pid [read-only] |
1445 | |
1606 | |
1446 | The process id this watcher watches out for, or C<0>, meaning any process id. |
1607 | The process id this watcher watches out for, or C<0>, meaning any process id. |
1447 | |
1608 | |
… | |
… | |
1456 | |
1617 | |
1457 | =back |
1618 | =back |
1458 | |
1619 | |
1459 | =head3 Examples |
1620 | =head3 Examples |
1460 | |
1621 | |
1461 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
1622 | Example: C<fork()> a new process and install a child handler to wait for |
|
|
1623 | its completion. |
1462 | |
1624 | |
|
|
1625 | ev_child cw; |
|
|
1626 | |
1463 | static void |
1627 | static void |
1464 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1628 | child_cb (EV_P_ struct ev_child *w, int revents) |
1465 | { |
1629 | { |
1466 | ev_unloop (loop, EVUNLOOP_ALL); |
1630 | ev_child_stop (EV_A_ w); |
|
|
1631 | printf ("process %d exited with status %x\n", w->rpid, w->rstatus); |
1467 | } |
1632 | } |
1468 | |
1633 | |
1469 | struct ev_signal signal_watcher; |
1634 | pid_t pid = fork (); |
1470 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1635 | |
1471 | ev_signal_start (loop, &sigint_cb); |
1636 | if (pid < 0) |
|
|
1637 | // error |
|
|
1638 | else if (pid == 0) |
|
|
1639 | { |
|
|
1640 | // the forked child executes here |
|
|
1641 | exit (1); |
|
|
1642 | } |
|
|
1643 | else |
|
|
1644 | { |
|
|
1645 | ev_child_init (&cw, child_cb, pid, 0); |
|
|
1646 | ev_child_start (EV_DEFAULT_ &cw); |
|
|
1647 | } |
1472 | |
1648 | |
1473 | |
1649 | |
1474 | =head2 C<ev_stat> - did the file attributes just change? |
1650 | =head2 C<ev_stat> - did the file attributes just change? |
1475 | |
1651 | |
1476 | This watches a filesystem path for attribute changes. That is, it calls |
1652 | This watches a file system path for attribute changes. That is, it calls |
1477 | C<stat> regularly (or when the OS says it changed) and sees if it changed |
1653 | C<stat> regularly (or when the OS says it changed) and sees if it changed |
1478 | compared to the last time, invoking the callback if it did. |
1654 | compared to the last time, invoking the callback if it did. |
1479 | |
1655 | |
1480 | The path does not need to exist: changing from "path exists" to "path does |
1656 | The path does not need to exist: changing from "path exists" to "path does |
1481 | not exist" is a status change like any other. The condition "path does |
1657 | not exist" is a status change like any other. The condition "path does |
… | |
… | |
1499 | as even with OS-supported change notifications, this can be |
1675 | as even with OS-supported change notifications, this can be |
1500 | resource-intensive. |
1676 | resource-intensive. |
1501 | |
1677 | |
1502 | At the time of this writing, only the Linux inotify interface is |
1678 | At the time of this writing, only the Linux inotify interface is |
1503 | implemented (implementing kqueue support is left as an exercise for the |
1679 | implemented (implementing kqueue support is left as an exercise for the |
|
|
1680 | reader, note, however, that the author sees no way of implementing ev_stat |
1504 | reader). Inotify will be used to give hints only and should not change the |
1681 | semantics with kqueue). Inotify will be used to give hints only and should |
1505 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
1682 | not change the semantics of C<ev_stat> watchers, which means that libev |
1506 | to fall back to regular polling again even with inotify, but changes are |
1683 | sometimes needs to fall back to regular polling again even with inotify, |
1507 | usually detected immediately, and if the file exists there will be no |
1684 | but changes are usually detected immediately, and if the file exists there |
1508 | polling. |
1685 | will be no polling. |
|
|
1686 | |
|
|
1687 | =head3 ABI Issues (Largefile Support) |
|
|
1688 | |
|
|
1689 | Libev by default (unless the user overrides this) uses the default |
|
|
1690 | compilation environment, which means that on systems with large file |
|
|
1691 | support disabled by default, you get the 32 bit version of the stat |
|
|
1692 | structure. When using the library from programs that change the ABI to |
|
|
1693 | use 64 bit file offsets the programs will fail. In that case you have to |
|
|
1694 | compile libev with the same flags to get binary compatibility. This is |
|
|
1695 | obviously the case with any flags that change the ABI, but the problem is |
|
|
1696 | most noticeably disabled with ev_stat and large file support. |
|
|
1697 | |
|
|
1698 | The solution for this is to lobby your distribution maker to make large |
|
|
1699 | file interfaces available by default (as e.g. FreeBSD does) and not |
|
|
1700 | optional. Libev cannot simply switch on large file support because it has |
|
|
1701 | to exchange stat structures with application programs compiled using the |
|
|
1702 | default compilation environment. |
1509 | |
1703 | |
1510 | =head3 Inotify |
1704 | =head3 Inotify |
1511 | |
1705 | |
1512 | When C<inotify (7)> support has been compiled into libev (generally only |
1706 | When C<inotify (7)> support has been compiled into libev (generally only |
1513 | available on Linux) and present at runtime, it will be used to speed up |
1707 | available on Linux) and present at runtime, it will be used to speed up |
1514 | change detection where possible. The inotify descriptor will be created lazily |
1708 | change detection where possible. The inotify descriptor will be created lazily |
1515 | when the first C<ev_stat> watcher is being started. |
1709 | when the first C<ev_stat> watcher is being started. |
1516 | |
1710 | |
1517 | Inotify presense does not change the semantics of C<ev_stat> watchers |
1711 | Inotify presence does not change the semantics of C<ev_stat> watchers |
1518 | except that changes might be detected earlier, and in some cases, to avoid |
1712 | except that changes might be detected earlier, and in some cases, to avoid |
1519 | making regular C<stat> calls. Even in the presense of inotify support |
1713 | making regular C<stat> calls. Even in the presence of inotify support |
1520 | there are many cases where libev has to resort to regular C<stat> polling. |
1714 | there are many cases where libev has to resort to regular C<stat> polling. |
1521 | |
1715 | |
1522 | (There is no support for kqueue, as apparently it cannot be used to |
1716 | (There is no support for kqueue, as apparently it cannot be used to |
1523 | implement this functionality, due to the requirement of having a file |
1717 | implement this functionality, due to the requirement of having a file |
1524 | descriptor open on the object at all times). |
1718 | descriptor open on the object at all times). |
1525 | |
1719 | |
1526 | =head3 The special problem of stat time resolution |
1720 | =head3 The special problem of stat time resolution |
1527 | |
1721 | |
1528 | The C<stat ()> syscall only supports full-second resolution portably, and |
1722 | The C<stat ()> system call only supports full-second resolution portably, and |
1529 | even on systems where the resolution is higher, many filesystems still |
1723 | even on systems where the resolution is higher, many file systems still |
1530 | only support whole seconds. |
1724 | only support whole seconds. |
1531 | |
1725 | |
1532 | That means that, if the time is the only thing that changes, you might |
1726 | That means that, if the time is the only thing that changes, you can |
1533 | miss updates: on the first update, C<ev_stat> detects a change and calls |
1727 | easily miss updates: on the first update, C<ev_stat> detects a change and |
1534 | your callback, which does something. When there is another update within |
1728 | calls your callback, which does something. When there is another update |
1535 | the same second, C<ev_stat> will be unable to detect it. |
1729 | within the same second, C<ev_stat> will be unable to detect it as the stat |
|
|
1730 | data does not change. |
1536 | |
1731 | |
1537 | The solution to this is to delay acting on a change for a second (or till |
1732 | The solution to this is to delay acting on a change for slightly more |
1538 | the next second boundary), using a roughly one-second delay C<ev_timer> |
1733 | than a second (or till slightly after the next full second boundary), using |
1539 | (C<ev_timer_set (w, 0., 1.01); ev_timer_again (loop, w)>). The C<.01> |
1734 | a roughly one-second-delay C<ev_timer> (e.g. C<ev_timer_set (w, 0., 1.02); |
1540 | is added to work around small timing inconsistencies of some operating |
1735 | ev_timer_again (loop, w)>). |
1541 | systems. |
1736 | |
|
|
1737 | The C<.02> offset is added to work around small timing inconsistencies |
|
|
1738 | of some operating systems (where the second counter of the current time |
|
|
1739 | might be be delayed. One such system is the Linux kernel, where a call to |
|
|
1740 | C<gettimeofday> might return a timestamp with a full second later than |
|
|
1741 | a subsequent C<time> call - if the equivalent of C<time ()> is used to |
|
|
1742 | update file times then there will be a small window where the kernel uses |
|
|
1743 | the previous second to update file times but libev might already execute |
|
|
1744 | the timer callback). |
1542 | |
1745 | |
1543 | =head3 Watcher-Specific Functions and Data Members |
1746 | =head3 Watcher-Specific Functions and Data Members |
1544 | |
1747 | |
1545 | =over 4 |
1748 | =over 4 |
1546 | |
1749 | |
… | |
… | |
1552 | C<path>. The C<interval> is a hint on how quickly a change is expected to |
1755 | C<path>. The C<interval> is a hint on how quickly a change is expected to |
1553 | be detected and should normally be specified as C<0> to let libev choose |
1756 | be detected and should normally be specified as C<0> to let libev choose |
1554 | a suitable value. The memory pointed to by C<path> must point to the same |
1757 | a suitable value. The memory pointed to by C<path> must point to the same |
1555 | path for as long as the watcher is active. |
1758 | path for as long as the watcher is active. |
1556 | |
1759 | |
1557 | The callback will be receive C<EV_STAT> when a change was detected, |
1760 | The callback will receive C<EV_STAT> when a change was detected, relative |
1558 | relative to the attributes at the time the watcher was started (or the |
1761 | to the attributes at the time the watcher was started (or the last change |
1559 | last change was detected). |
1762 | was detected). |
1560 | |
1763 | |
1561 | =item ev_stat_stat (ev_stat *) |
1764 | =item ev_stat_stat (loop, ev_stat *) |
1562 | |
1765 | |
1563 | Updates the stat buffer immediately with new values. If you change the |
1766 | Updates the stat buffer immediately with new values. If you change the |
1564 | watched path in your callback, you could call this fucntion to avoid |
1767 | watched path in your callback, you could call this function to avoid |
1565 | detecting this change (while introducing a race condition). Can also be |
1768 | detecting this change (while introducing a race condition if you are not |
1566 | useful simply to find out the new values. |
1769 | the only one changing the path). Can also be useful simply to find out the |
|
|
1770 | new values. |
1567 | |
1771 | |
1568 | =item ev_statdata attr [read-only] |
1772 | =item ev_statdata attr [read-only] |
1569 | |
1773 | |
1570 | The most-recently detected attributes of the file. Although the type is of |
1774 | The most-recently detected attributes of the file. Although the type is |
1571 | C<ev_statdata>, this is usually the (or one of the) C<struct stat> types |
1775 | C<ev_statdata>, this is usually the (or one of the) C<struct stat> types |
1572 | suitable for your system. If the C<st_nlink> member is C<0>, then there |
1776 | suitable for your system, but you can only rely on the POSIX-standardised |
|
|
1777 | members to be present. If the C<st_nlink> member is C<0>, then there was |
1573 | was some error while C<stat>ing the file. |
1778 | some error while C<stat>ing the file. |
1574 | |
1779 | |
1575 | =item ev_statdata prev [read-only] |
1780 | =item ev_statdata prev [read-only] |
1576 | |
1781 | |
1577 | The previous attributes of the file. The callback gets invoked whenever |
1782 | The previous attributes of the file. The callback gets invoked whenever |
1578 | C<prev> != C<attr>. |
1783 | C<prev> != C<attr>, or, more precisely, one or more of these members |
|
|
1784 | differ: C<st_dev>, C<st_ino>, C<st_mode>, C<st_nlink>, C<st_uid>, |
|
|
1785 | C<st_gid>, C<st_rdev>, C<st_size>, C<st_atime>, C<st_mtime>, C<st_ctime>. |
1579 | |
1786 | |
1580 | =item ev_tstamp interval [read-only] |
1787 | =item ev_tstamp interval [read-only] |
1581 | |
1788 | |
1582 | The specified interval. |
1789 | The specified interval. |
1583 | |
1790 | |
1584 | =item const char *path [read-only] |
1791 | =item const char *path [read-only] |
1585 | |
1792 | |
1586 | The filesystem path that is being watched. |
1793 | The file system path that is being watched. |
1587 | |
1794 | |
1588 | =back |
1795 | =back |
1589 | |
1796 | |
1590 | =head3 Examples |
1797 | =head3 Examples |
1591 | |
1798 | |
1592 | Example: Watch C</etc/passwd> for attribute changes. |
1799 | Example: Watch C</etc/passwd> for attribute changes. |
1593 | |
1800 | |
1594 | static void |
1801 | static void |
1595 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
1802 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
1596 | { |
1803 | { |
1597 | /* /etc/passwd changed in some way */ |
1804 | /* /etc/passwd changed in some way */ |
1598 | if (w->attr.st_nlink) |
1805 | if (w->attr.st_nlink) |
1599 | { |
1806 | { |
1600 | printf ("passwd current size %ld\n", (long)w->attr.st_size); |
1807 | printf ("passwd current size %ld\n", (long)w->attr.st_size); |
1601 | printf ("passwd current atime %ld\n", (long)w->attr.st_mtime); |
1808 | printf ("passwd current atime %ld\n", (long)w->attr.st_mtime); |
1602 | printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime); |
1809 | printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime); |
1603 | } |
1810 | } |
1604 | else |
1811 | else |
1605 | /* you shalt not abuse printf for puts */ |
1812 | /* you shalt not abuse printf for puts */ |
1606 | puts ("wow, /etc/passwd is not there, expect problems. " |
1813 | puts ("wow, /etc/passwd is not there, expect problems. " |
1607 | "if this is windows, they already arrived\n"); |
1814 | "if this is windows, they already arrived\n"); |
1608 | } |
1815 | } |
1609 | |
1816 | |
1610 | ... |
1817 | ... |
1611 | ev_stat passwd; |
1818 | ev_stat passwd; |
1612 | |
1819 | |
1613 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.); |
1820 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.); |
1614 | ev_stat_start (loop, &passwd); |
1821 | ev_stat_start (loop, &passwd); |
1615 | |
1822 | |
1616 | Example: Like above, but additionally use a one-second delay so we do not |
1823 | Example: Like above, but additionally use a one-second delay so we do not |
1617 | miss updates (however, frequent updates will delay processing, too, so |
1824 | miss updates (however, frequent updates will delay processing, too, so |
1618 | one might do the work both on C<ev_stat> callback invocation I<and> on |
1825 | one might do the work both on C<ev_stat> callback invocation I<and> on |
1619 | C<ev_timer> callback invocation). |
1826 | C<ev_timer> callback invocation). |
1620 | |
1827 | |
1621 | static ev_stat passwd; |
1828 | static ev_stat passwd; |
1622 | static ev_timer timer; |
1829 | static ev_timer timer; |
1623 | |
1830 | |
1624 | static void |
1831 | static void |
1625 | timer_cb (EV_P_ ev_timer *w, int revents) |
1832 | timer_cb (EV_P_ ev_timer *w, int revents) |
1626 | { |
1833 | { |
1627 | ev_timer_stop (EV_A_ w); |
1834 | ev_timer_stop (EV_A_ w); |
1628 | |
1835 | |
1629 | /* now it's one second after the most recent passwd change */ |
1836 | /* now it's one second after the most recent passwd change */ |
1630 | } |
1837 | } |
1631 | |
1838 | |
1632 | static void |
1839 | static void |
1633 | stat_cb (EV_P_ ev_stat *w, int revents) |
1840 | stat_cb (EV_P_ ev_stat *w, int revents) |
1634 | { |
1841 | { |
1635 | /* reset the one-second timer */ |
1842 | /* reset the one-second timer */ |
1636 | ev_timer_again (EV_A_ &timer); |
1843 | ev_timer_again (EV_A_ &timer); |
1637 | } |
1844 | } |
1638 | |
1845 | |
1639 | ... |
1846 | ... |
1640 | ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); |
1847 | ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); |
1641 | ev_stat_start (loop, &passwd); |
1848 | ev_stat_start (loop, &passwd); |
1642 | ev_timer_init (&timer, timer_cb, 0., 1.01); |
1849 | ev_timer_init (&timer, timer_cb, 0., 1.02); |
1643 | |
1850 | |
1644 | |
1851 | |
1645 | =head2 C<ev_idle> - when you've got nothing better to do... |
1852 | =head2 C<ev_idle> - when you've got nothing better to do... |
1646 | |
1853 | |
1647 | Idle watchers trigger events when no other events of the same or higher |
1854 | Idle watchers trigger events when no other events of the same or higher |
… | |
… | |
1678 | =head3 Examples |
1885 | =head3 Examples |
1679 | |
1886 | |
1680 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1887 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1681 | callback, free it. Also, use no error checking, as usual. |
1888 | callback, free it. Also, use no error checking, as usual. |
1682 | |
1889 | |
1683 | static void |
1890 | static void |
1684 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1891 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1685 | { |
1892 | { |
1686 | free (w); |
1893 | free (w); |
1687 | // now do something you wanted to do when the program has |
1894 | // now do something you wanted to do when the program has |
1688 | // no longer asnything immediate to do. |
1895 | // no longer anything immediate to do. |
1689 | } |
1896 | } |
1690 | |
1897 | |
1691 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1898 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1692 | ev_idle_init (idle_watcher, idle_cb); |
1899 | ev_idle_init (idle_watcher, idle_cb); |
1693 | ev_idle_start (loop, idle_cb); |
1900 | ev_idle_start (loop, idle_cb); |
1694 | |
1901 | |
1695 | |
1902 | |
1696 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
1903 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
1697 | |
1904 | |
1698 | Prepare and check watchers are usually (but not always) used in tandem: |
1905 | Prepare and check watchers are usually (but not always) used in tandem: |
… | |
… | |
1717 | |
1924 | |
1718 | This is done by examining in each prepare call which file descriptors need |
1925 | This is done by examining in each prepare call which file descriptors need |
1719 | to be watched by the other library, registering C<ev_io> watchers for |
1926 | to be watched by the other library, registering C<ev_io> watchers for |
1720 | them and starting an C<ev_timer> watcher for any timeouts (many libraries |
1927 | them and starting an C<ev_timer> watcher for any timeouts (many libraries |
1721 | provide just this functionality). Then, in the check watcher you check for |
1928 | provide just this functionality). Then, in the check watcher you check for |
1722 | any events that occured (by checking the pending status of all watchers |
1929 | any events that occurred (by checking the pending status of all watchers |
1723 | and stopping them) and call back into the library. The I/O and timer |
1930 | and stopping them) and call back into the library. The I/O and timer |
1724 | callbacks will never actually be called (but must be valid nevertheless, |
1931 | callbacks will never actually be called (but must be valid nevertheless, |
1725 | because you never know, you know?). |
1932 | because you never know, you know?). |
1726 | |
1933 | |
1727 | As another example, the Perl Coro module uses these hooks to integrate |
1934 | As another example, the Perl Coro module uses these hooks to integrate |
… | |
… | |
1735 | |
1942 | |
1736 | It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>) |
1943 | It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>) |
1737 | priority, to ensure that they are being run before any other watchers |
1944 | priority, to ensure that they are being run before any other watchers |
1738 | after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers, |
1945 | after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers, |
1739 | too) should not activate ("feed") events into libev. While libev fully |
1946 | too) should not activate ("feed") events into libev. While libev fully |
1740 | supports this, they will be called before other C<ev_check> watchers |
1947 | supports this, they might get executed before other C<ev_check> watchers |
1741 | did their job. As C<ev_check> watchers are often used to embed other |
1948 | did their job. As C<ev_check> watchers are often used to embed other |
1742 | (non-libev) event loops those other event loops might be in an unusable |
1949 | (non-libev) event loops those other event loops might be in an unusable |
1743 | state until their C<ev_check> watcher ran (always remind yourself to |
1950 | state until their C<ev_check> watcher ran (always remind yourself to |
1744 | coexist peacefully with others). |
1951 | coexist peacefully with others). |
1745 | |
1952 | |
… | |
… | |
1760 | =head3 Examples |
1967 | =head3 Examples |
1761 | |
1968 | |
1762 | There are a number of principal ways to embed other event loops or modules |
1969 | There are a number of principal ways to embed other event loops or modules |
1763 | into libev. Here are some ideas on how to include libadns into libev |
1970 | into libev. Here are some ideas on how to include libadns into libev |
1764 | (there is a Perl module named C<EV::ADNS> that does this, which you could |
1971 | (there is a Perl module named C<EV::ADNS> that does this, which you could |
1765 | use for an actually working example. Another Perl module named C<EV::Glib> |
1972 | use as a working example. Another Perl module named C<EV::Glib> embeds a |
1766 | embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV |
1973 | Glib main context into libev, and finally, C<Glib::EV> embeds EV into the |
1767 | into the Glib event loop). |
1974 | Glib event loop). |
1768 | |
1975 | |
1769 | Method 1: Add IO watchers and a timeout watcher in a prepare handler, |
1976 | Method 1: Add IO watchers and a timeout watcher in a prepare handler, |
1770 | and in a check watcher, destroy them and call into libadns. What follows |
1977 | and in a check watcher, destroy them and call into libadns. What follows |
1771 | is pseudo-code only of course. This requires you to either use a low |
1978 | is pseudo-code only of course. This requires you to either use a low |
1772 | priority for the check watcher or use C<ev_clear_pending> explicitly, as |
1979 | priority for the check watcher or use C<ev_clear_pending> explicitly, as |
1773 | the callbacks for the IO/timeout watchers might not have been called yet. |
1980 | the callbacks for the IO/timeout watchers might not have been called yet. |
1774 | |
1981 | |
1775 | static ev_io iow [nfd]; |
1982 | static ev_io iow [nfd]; |
1776 | static ev_timer tw; |
1983 | static ev_timer tw; |
1777 | |
1984 | |
1778 | static void |
1985 | static void |
1779 | io_cb (ev_loop *loop, ev_io *w, int revents) |
1986 | io_cb (ev_loop *loop, ev_io *w, int revents) |
1780 | { |
1987 | { |
1781 | } |
1988 | } |
1782 | |
1989 | |
1783 | // create io watchers for each fd and a timer before blocking |
1990 | // create io watchers for each fd and a timer before blocking |
1784 | static void |
1991 | static void |
1785 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1992 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1786 | { |
1993 | { |
1787 | int timeout = 3600000; |
1994 | int timeout = 3600000; |
1788 | struct pollfd fds [nfd]; |
1995 | struct pollfd fds [nfd]; |
1789 | // actual code will need to loop here and realloc etc. |
1996 | // actual code will need to loop here and realloc etc. |
1790 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1997 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1791 | |
1998 | |
1792 | /* the callback is illegal, but won't be called as we stop during check */ |
1999 | /* the callback is illegal, but won't be called as we stop during check */ |
1793 | ev_timer_init (&tw, 0, timeout * 1e-3); |
2000 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1794 | ev_timer_start (loop, &tw); |
2001 | ev_timer_start (loop, &tw); |
1795 | |
2002 | |
1796 | // create one ev_io per pollfd |
2003 | // create one ev_io per pollfd |
1797 | for (int i = 0; i < nfd; ++i) |
2004 | for (int i = 0; i < nfd; ++i) |
1798 | { |
2005 | { |
1799 | ev_io_init (iow + i, io_cb, fds [i].fd, |
2006 | ev_io_init (iow + i, io_cb, fds [i].fd, |
1800 | ((fds [i].events & POLLIN ? EV_READ : 0) |
2007 | ((fds [i].events & POLLIN ? EV_READ : 0) |
1801 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
2008 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1802 | |
2009 | |
1803 | fds [i].revents = 0; |
2010 | fds [i].revents = 0; |
1804 | ev_io_start (loop, iow + i); |
2011 | ev_io_start (loop, iow + i); |
1805 | } |
2012 | } |
1806 | } |
2013 | } |
1807 | |
2014 | |
1808 | // stop all watchers after blocking |
2015 | // stop all watchers after blocking |
1809 | static void |
2016 | static void |
1810 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
2017 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
1811 | { |
2018 | { |
1812 | ev_timer_stop (loop, &tw); |
2019 | ev_timer_stop (loop, &tw); |
1813 | |
2020 | |
1814 | for (int i = 0; i < nfd; ++i) |
2021 | for (int i = 0; i < nfd; ++i) |
1815 | { |
2022 | { |
1816 | // set the relevant poll flags |
2023 | // set the relevant poll flags |
1817 | // could also call adns_processreadable etc. here |
2024 | // could also call adns_processreadable etc. here |
1818 | struct pollfd *fd = fds + i; |
2025 | struct pollfd *fd = fds + i; |
1819 | int revents = ev_clear_pending (iow + i); |
2026 | int revents = ev_clear_pending (iow + i); |
1820 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
2027 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
1821 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
2028 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
1822 | |
2029 | |
1823 | // now stop the watcher |
2030 | // now stop the watcher |
1824 | ev_io_stop (loop, iow + i); |
2031 | ev_io_stop (loop, iow + i); |
1825 | } |
2032 | } |
1826 | |
2033 | |
1827 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
2034 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
1828 | } |
2035 | } |
1829 | |
2036 | |
1830 | Method 2: This would be just like method 1, but you run C<adns_afterpoll> |
2037 | Method 2: This would be just like method 1, but you run C<adns_afterpoll> |
1831 | in the prepare watcher and would dispose of the check watcher. |
2038 | in the prepare watcher and would dispose of the check watcher. |
1832 | |
2039 | |
1833 | Method 3: If the module to be embedded supports explicit event |
2040 | Method 3: If the module to be embedded supports explicit event |
1834 | notification (adns does), you can also make use of the actual watcher |
2041 | notification (libadns does), you can also make use of the actual watcher |
1835 | callbacks, and only destroy/create the watchers in the prepare watcher. |
2042 | callbacks, and only destroy/create the watchers in the prepare watcher. |
1836 | |
2043 | |
1837 | static void |
2044 | static void |
1838 | timer_cb (EV_P_ ev_timer *w, int revents) |
2045 | timer_cb (EV_P_ ev_timer *w, int revents) |
1839 | { |
2046 | { |
1840 | adns_state ads = (adns_state)w->data; |
2047 | adns_state ads = (adns_state)w->data; |
1841 | update_now (EV_A); |
2048 | update_now (EV_A); |
1842 | |
2049 | |
1843 | adns_processtimeouts (ads, &tv_now); |
2050 | adns_processtimeouts (ads, &tv_now); |
1844 | } |
2051 | } |
1845 | |
2052 | |
1846 | static void |
2053 | static void |
1847 | io_cb (EV_P_ ev_io *w, int revents) |
2054 | io_cb (EV_P_ ev_io *w, int revents) |
1848 | { |
2055 | { |
1849 | adns_state ads = (adns_state)w->data; |
2056 | adns_state ads = (adns_state)w->data; |
1850 | update_now (EV_A); |
2057 | update_now (EV_A); |
1851 | |
2058 | |
1852 | if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now); |
2059 | if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now); |
1853 | if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now); |
2060 | if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now); |
1854 | } |
2061 | } |
1855 | |
2062 | |
1856 | // do not ever call adns_afterpoll |
2063 | // do not ever call adns_afterpoll |
1857 | |
2064 | |
1858 | Method 4: Do not use a prepare or check watcher because the module you |
2065 | Method 4: Do not use a prepare or check watcher because the module you |
1859 | want to embed is too inflexible to support it. Instead, youc na override |
2066 | want to embed is too inflexible to support it. Instead, you can override |
1860 | their poll function. The drawback with this solution is that the main |
2067 | their poll function. The drawback with this solution is that the main |
1861 | loop is now no longer controllable by EV. The C<Glib::EV> module does |
2068 | loop is now no longer controllable by EV. The C<Glib::EV> module does |
1862 | this. |
2069 | this. |
1863 | |
2070 | |
1864 | static gint |
2071 | static gint |
1865 | event_poll_func (GPollFD *fds, guint nfds, gint timeout) |
2072 | event_poll_func (GPollFD *fds, guint nfds, gint timeout) |
1866 | { |
2073 | { |
1867 | int got_events = 0; |
2074 | int got_events = 0; |
1868 | |
2075 | |
1869 | for (n = 0; n < nfds; ++n) |
2076 | for (n = 0; n < nfds; ++n) |
1870 | // create/start io watcher that sets the relevant bits in fds[n] and increment got_events |
2077 | // create/start io watcher that sets the relevant bits in fds[n] and increment got_events |
1871 | |
2078 | |
1872 | if (timeout >= 0) |
2079 | if (timeout >= 0) |
1873 | // create/start timer |
2080 | // create/start timer |
1874 | |
2081 | |
1875 | // poll |
2082 | // poll |
1876 | ev_loop (EV_A_ 0); |
2083 | ev_loop (EV_A_ 0); |
1877 | |
2084 | |
1878 | // stop timer again |
2085 | // stop timer again |
1879 | if (timeout >= 0) |
2086 | if (timeout >= 0) |
1880 | ev_timer_stop (EV_A_ &to); |
2087 | ev_timer_stop (EV_A_ &to); |
1881 | |
2088 | |
1882 | // stop io watchers again - their callbacks should have set |
2089 | // stop io watchers again - their callbacks should have set |
1883 | for (n = 0; n < nfds; ++n) |
2090 | for (n = 0; n < nfds; ++n) |
1884 | ev_io_stop (EV_A_ iow [n]); |
2091 | ev_io_stop (EV_A_ iow [n]); |
1885 | |
2092 | |
1886 | return got_events; |
2093 | return got_events; |
1887 | } |
2094 | } |
1888 | |
2095 | |
1889 | |
2096 | |
1890 | =head2 C<ev_embed> - when one backend isn't enough... |
2097 | =head2 C<ev_embed> - when one backend isn't enough... |
1891 | |
2098 | |
1892 | This is a rather advanced watcher type that lets you embed one event loop |
2099 | This is a rather advanced watcher type that lets you embed one event loop |
… | |
… | |
1948 | |
2155 | |
1949 | Configures the watcher to embed the given loop, which must be |
2156 | Configures the watcher to embed the given loop, which must be |
1950 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
2157 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
1951 | invoked automatically, otherwise it is the responsibility of the callback |
2158 | invoked automatically, otherwise it is the responsibility of the callback |
1952 | to invoke it (it will continue to be called until the sweep has been done, |
2159 | to invoke it (it will continue to be called until the sweep has been done, |
1953 | if you do not want thta, you need to temporarily stop the embed watcher). |
2160 | if you do not want that, you need to temporarily stop the embed watcher). |
1954 | |
2161 | |
1955 | =item ev_embed_sweep (loop, ev_embed *) |
2162 | =item ev_embed_sweep (loop, ev_embed *) |
1956 | |
2163 | |
1957 | Make a single, non-blocking sweep over the embedded loop. This works |
2164 | Make a single, non-blocking sweep over the embedded loop. This works |
1958 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
2165 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
1959 | apropriate way for embedded loops. |
2166 | appropriate way for embedded loops. |
1960 | |
2167 | |
1961 | =item struct ev_loop *other [read-only] |
2168 | =item struct ev_loop *other [read-only] |
1962 | |
2169 | |
1963 | The embedded event loop. |
2170 | The embedded event loop. |
1964 | |
2171 | |
… | |
… | |
1966 | |
2173 | |
1967 | =head3 Examples |
2174 | =head3 Examples |
1968 | |
2175 | |
1969 | Example: Try to get an embeddable event loop and embed it into the default |
2176 | Example: Try to get an embeddable event loop and embed it into the default |
1970 | event loop. If that is not possible, use the default loop. The default |
2177 | event loop. If that is not possible, use the default loop. The default |
1971 | loop is stored in C<loop_hi>, while the mebeddable loop is stored in |
2178 | loop is stored in C<loop_hi>, while the embeddable loop is stored in |
1972 | C<loop_lo> (which is C<loop_hi> in the acse no embeddable loop can be |
2179 | C<loop_lo> (which is C<loop_hi> in the case no embeddable loop can be |
1973 | used). |
2180 | used). |
1974 | |
2181 | |
1975 | struct ev_loop *loop_hi = ev_default_init (0); |
2182 | struct ev_loop *loop_hi = ev_default_init (0); |
1976 | struct ev_loop *loop_lo = 0; |
2183 | struct ev_loop *loop_lo = 0; |
1977 | struct ev_embed embed; |
2184 | struct ev_embed embed; |
1978 | |
2185 | |
1979 | // see if there is a chance of getting one that works |
2186 | // see if there is a chance of getting one that works |
1980 | // (remember that a flags value of 0 means autodetection) |
2187 | // (remember that a flags value of 0 means autodetection) |
1981 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
2188 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
1982 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
2189 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
1983 | : 0; |
2190 | : 0; |
1984 | |
2191 | |
1985 | // if we got one, then embed it, otherwise default to loop_hi |
2192 | // if we got one, then embed it, otherwise default to loop_hi |
1986 | if (loop_lo) |
2193 | if (loop_lo) |
1987 | { |
2194 | { |
1988 | ev_embed_init (&embed, 0, loop_lo); |
2195 | ev_embed_init (&embed, 0, loop_lo); |
1989 | ev_embed_start (loop_hi, &embed); |
2196 | ev_embed_start (loop_hi, &embed); |
1990 | } |
2197 | } |
1991 | else |
2198 | else |
1992 | loop_lo = loop_hi; |
2199 | loop_lo = loop_hi; |
1993 | |
2200 | |
1994 | Example: Check if kqueue is available but not recommended and create |
2201 | Example: Check if kqueue is available but not recommended and create |
1995 | a kqueue backend for use with sockets (which usually work with any |
2202 | a kqueue backend for use with sockets (which usually work with any |
1996 | kqueue implementation). Store the kqueue/socket-only event loop in |
2203 | kqueue implementation). Store the kqueue/socket-only event loop in |
1997 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
2204 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
1998 | |
2205 | |
1999 | struct ev_loop *loop = ev_default_init (0); |
2206 | struct ev_loop *loop = ev_default_init (0); |
2000 | struct ev_loop *loop_socket = 0; |
2207 | struct ev_loop *loop_socket = 0; |
2001 | struct ev_embed embed; |
2208 | struct ev_embed embed; |
2002 | |
2209 | |
2003 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
2210 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
2004 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
2211 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
2005 | { |
2212 | { |
2006 | ev_embed_init (&embed, 0, loop_socket); |
2213 | ev_embed_init (&embed, 0, loop_socket); |
2007 | ev_embed_start (loop, &embed); |
2214 | ev_embed_start (loop, &embed); |
2008 | } |
2215 | } |
2009 | |
2216 | |
2010 | if (!loop_socket) |
2217 | if (!loop_socket) |
2011 | loop_socket = loop; |
2218 | loop_socket = loop; |
2012 | |
2219 | |
2013 | // now use loop_socket for all sockets, and loop for everything else |
2220 | // now use loop_socket for all sockets, and loop for everything else |
2014 | |
2221 | |
2015 | |
2222 | |
2016 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
2223 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
2017 | |
2224 | |
2018 | Fork watchers are called when a C<fork ()> was detected (usually because |
2225 | Fork watchers are called when a C<fork ()> was detected (usually because |
… | |
… | |
2034 | believe me. |
2241 | believe me. |
2035 | |
2242 | |
2036 | =back |
2243 | =back |
2037 | |
2244 | |
2038 | |
2245 | |
|
|
2246 | =head2 C<ev_async> - how to wake up another event loop |
|
|
2247 | |
|
|
2248 | In general, you cannot use an C<ev_loop> from multiple threads or other |
|
|
2249 | asynchronous sources such as signal handlers (as opposed to multiple event |
|
|
2250 | loops - those are of course safe to use in different threads). |
|
|
2251 | |
|
|
2252 | Sometimes, however, you need to wake up another event loop you do not |
|
|
2253 | control, for example because it belongs to another thread. This is what |
|
|
2254 | C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you |
|
|
2255 | can signal it by calling C<ev_async_send>, which is thread- and signal |
|
|
2256 | safe. |
|
|
2257 | |
|
|
2258 | This functionality is very similar to C<ev_signal> watchers, as signals, |
|
|
2259 | too, are asynchronous in nature, and signals, too, will be compressed |
|
|
2260 | (i.e. the number of callback invocations may be less than the number of |
|
|
2261 | C<ev_async_sent> calls). |
|
|
2262 | |
|
|
2263 | Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not |
|
|
2264 | just the default loop. |
|
|
2265 | |
|
|
2266 | =head3 Queueing |
|
|
2267 | |
|
|
2268 | C<ev_async> does not support queueing of data in any way. The reason |
|
|
2269 | is that the author does not know of a simple (or any) algorithm for a |
|
|
2270 | multiple-writer-single-reader queue that works in all cases and doesn't |
|
|
2271 | need elaborate support such as pthreads. |
|
|
2272 | |
|
|
2273 | That means that if you want to queue data, you have to provide your own |
|
|
2274 | queue. But at least I can tell you would implement locking around your |
|
|
2275 | queue: |
|
|
2276 | |
|
|
2277 | =over 4 |
|
|
2278 | |
|
|
2279 | =item queueing from a signal handler context |
|
|
2280 | |
|
|
2281 | To implement race-free queueing, you simply add to the queue in the signal |
|
|
2282 | handler but you block the signal handler in the watcher callback. Here is an example that does that for |
|
|
2283 | some fictitious SIGUSR1 handler: |
|
|
2284 | |
|
|
2285 | static ev_async mysig; |
|
|
2286 | |
|
|
2287 | static void |
|
|
2288 | sigusr1_handler (void) |
|
|
2289 | { |
|
|
2290 | sometype data; |
|
|
2291 | |
|
|
2292 | // no locking etc. |
|
|
2293 | queue_put (data); |
|
|
2294 | ev_async_send (EV_DEFAULT_ &mysig); |
|
|
2295 | } |
|
|
2296 | |
|
|
2297 | static void |
|
|
2298 | mysig_cb (EV_P_ ev_async *w, int revents) |
|
|
2299 | { |
|
|
2300 | sometype data; |
|
|
2301 | sigset_t block, prev; |
|
|
2302 | |
|
|
2303 | sigemptyset (&block); |
|
|
2304 | sigaddset (&block, SIGUSR1); |
|
|
2305 | sigprocmask (SIG_BLOCK, &block, &prev); |
|
|
2306 | |
|
|
2307 | while (queue_get (&data)) |
|
|
2308 | process (data); |
|
|
2309 | |
|
|
2310 | if (sigismember (&prev, SIGUSR1) |
|
|
2311 | sigprocmask (SIG_UNBLOCK, &block, 0); |
|
|
2312 | } |
|
|
2313 | |
|
|
2314 | (Note: pthreads in theory requires you to use C<pthread_setmask> |
|
|
2315 | instead of C<sigprocmask> when you use threads, but libev doesn't do it |
|
|
2316 | either...). |
|
|
2317 | |
|
|
2318 | =item queueing from a thread context |
|
|
2319 | |
|
|
2320 | The strategy for threads is different, as you cannot (easily) block |
|
|
2321 | threads but you can easily preempt them, so to queue safely you need to |
|
|
2322 | employ a traditional mutex lock, such as in this pthread example: |
|
|
2323 | |
|
|
2324 | static ev_async mysig; |
|
|
2325 | static pthread_mutex_t mymutex = PTHREAD_MUTEX_INITIALIZER; |
|
|
2326 | |
|
|
2327 | static void |
|
|
2328 | otherthread (void) |
|
|
2329 | { |
|
|
2330 | // only need to lock the actual queueing operation |
|
|
2331 | pthread_mutex_lock (&mymutex); |
|
|
2332 | queue_put (data); |
|
|
2333 | pthread_mutex_unlock (&mymutex); |
|
|
2334 | |
|
|
2335 | ev_async_send (EV_DEFAULT_ &mysig); |
|
|
2336 | } |
|
|
2337 | |
|
|
2338 | static void |
|
|
2339 | mysig_cb (EV_P_ ev_async *w, int revents) |
|
|
2340 | { |
|
|
2341 | pthread_mutex_lock (&mymutex); |
|
|
2342 | |
|
|
2343 | while (queue_get (&data)) |
|
|
2344 | process (data); |
|
|
2345 | |
|
|
2346 | pthread_mutex_unlock (&mymutex); |
|
|
2347 | } |
|
|
2348 | |
|
|
2349 | =back |
|
|
2350 | |
|
|
2351 | |
|
|
2352 | =head3 Watcher-Specific Functions and Data Members |
|
|
2353 | |
|
|
2354 | =over 4 |
|
|
2355 | |
|
|
2356 | =item ev_async_init (ev_async *, callback) |
|
|
2357 | |
|
|
2358 | Initialises and configures the async watcher - it has no parameters of any |
|
|
2359 | kind. There is a C<ev_asynd_set> macro, but using it is utterly pointless, |
|
|
2360 | believe me. |
|
|
2361 | |
|
|
2362 | =item ev_async_send (loop, ev_async *) |
|
|
2363 | |
|
|
2364 | Sends/signals/activates the given C<ev_async> watcher, that is, feeds |
|
|
2365 | an C<EV_ASYNC> event on the watcher into the event loop. Unlike |
|
|
2366 | C<ev_feed_event>, this call is safe to do in other threads, signal or |
|
|
2367 | similar contexts (see the discussion of C<EV_ATOMIC_T> in the embedding |
|
|
2368 | section below on what exactly this means). |
|
|
2369 | |
|
|
2370 | This call incurs the overhead of a system call only once per loop iteration, |
|
|
2371 | so while the overhead might be noticeable, it doesn't apply to repeated |
|
|
2372 | calls to C<ev_async_send>. |
|
|
2373 | |
|
|
2374 | =item bool = ev_async_pending (ev_async *) |
|
|
2375 | |
|
|
2376 | Returns a non-zero value when C<ev_async_send> has been called on the |
|
|
2377 | watcher but the event has not yet been processed (or even noted) by the |
|
|
2378 | event loop. |
|
|
2379 | |
|
|
2380 | C<ev_async_send> sets a flag in the watcher and wakes up the loop. When |
|
|
2381 | the loop iterates next and checks for the watcher to have become active, |
|
|
2382 | it will reset the flag again. C<ev_async_pending> can be used to very |
|
|
2383 | quickly check whether invoking the loop might be a good idea. |
|
|
2384 | |
|
|
2385 | Not that this does I<not> check whether the watcher itself is pending, only |
|
|
2386 | whether it has been requested to make this watcher pending. |
|
|
2387 | |
|
|
2388 | =back |
|
|
2389 | |
|
|
2390 | |
2039 | =head1 OTHER FUNCTIONS |
2391 | =head1 OTHER FUNCTIONS |
2040 | |
2392 | |
2041 | There are some other functions of possible interest. Described. Here. Now. |
2393 | There are some other functions of possible interest. Described. Here. Now. |
2042 | |
2394 | |
2043 | =over 4 |
2395 | =over 4 |
… | |
… | |
2050 | or timeout without having to allocate/configure/start/stop/free one or |
2402 | or timeout without having to allocate/configure/start/stop/free one or |
2051 | more watchers yourself. |
2403 | more watchers yourself. |
2052 | |
2404 | |
2053 | If C<fd> is less than 0, then no I/O watcher will be started and events |
2405 | If C<fd> is less than 0, then no I/O watcher will be started and events |
2054 | is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and |
2406 | is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and |
2055 | C<events> set will be craeted and started. |
2407 | C<events> set will be created and started. |
2056 | |
2408 | |
2057 | If C<timeout> is less than 0, then no timeout watcher will be |
2409 | If C<timeout> is less than 0, then no timeout watcher will be |
2058 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
2410 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
2059 | repeat = 0) will be started. While C<0> is a valid timeout, it is of |
2411 | repeat = 0) will be started. While C<0> is a valid timeout, it is of |
2060 | dubious value. |
2412 | dubious value. |
… | |
… | |
2062 | The callback has the type C<void (*cb)(int revents, void *arg)> and gets |
2414 | The callback has the type C<void (*cb)(int revents, void *arg)> and gets |
2063 | passed an C<revents> set like normal event callbacks (a combination of |
2415 | passed an C<revents> set like normal event callbacks (a combination of |
2064 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg> |
2416 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg> |
2065 | value passed to C<ev_once>: |
2417 | value passed to C<ev_once>: |
2066 | |
2418 | |
2067 | static void stdin_ready (int revents, void *arg) |
2419 | static void stdin_ready (int revents, void *arg) |
2068 | { |
2420 | { |
2069 | if (revents & EV_TIMEOUT) |
2421 | if (revents & EV_TIMEOUT) |
2070 | /* doh, nothing entered */; |
2422 | /* doh, nothing entered */; |
2071 | else if (revents & EV_READ) |
2423 | else if (revents & EV_READ) |
2072 | /* stdin might have data for us, joy! */; |
2424 | /* stdin might have data for us, joy! */; |
2073 | } |
2425 | } |
2074 | |
2426 | |
2075 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
2427 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
2076 | |
2428 | |
2077 | =item ev_feed_event (ev_loop *, watcher *, int revents) |
2429 | =item ev_feed_event (ev_loop *, watcher *, int revents) |
2078 | |
2430 | |
2079 | Feeds the given event set into the event loop, as if the specified event |
2431 | Feeds the given event set into the event loop, as if the specified event |
2080 | had happened for the specified watcher (which must be a pointer to an |
2432 | had happened for the specified watcher (which must be a pointer to an |
… | |
… | |
2085 | Feed an event on the given fd, as if a file descriptor backend detected |
2437 | Feed an event on the given fd, as if a file descriptor backend detected |
2086 | the given events it. |
2438 | the given events it. |
2087 | |
2439 | |
2088 | =item ev_feed_signal_event (ev_loop *loop, int signum) |
2440 | =item ev_feed_signal_event (ev_loop *loop, int signum) |
2089 | |
2441 | |
2090 | Feed an event as if the given signal occured (C<loop> must be the default |
2442 | Feed an event as if the given signal occurred (C<loop> must be the default |
2091 | loop!). |
2443 | loop!). |
2092 | |
2444 | |
2093 | =back |
2445 | =back |
2094 | |
2446 | |
2095 | |
2447 | |
… | |
… | |
2111 | |
2463 | |
2112 | =item * Priorities are not currently supported. Initialising priorities |
2464 | =item * Priorities are not currently supported. Initialising priorities |
2113 | will fail and all watchers will have the same priority, even though there |
2465 | will fail and all watchers will have the same priority, even though there |
2114 | is an ev_pri field. |
2466 | is an ev_pri field. |
2115 | |
2467 | |
|
|
2468 | =item * In libevent, the last base created gets the signals, in libev, the |
|
|
2469 | first base created (== the default loop) gets the signals. |
|
|
2470 | |
2116 | =item * Other members are not supported. |
2471 | =item * Other members are not supported. |
2117 | |
2472 | |
2118 | =item * The libev emulation is I<not> ABI compatible to libevent, you need |
2473 | =item * The libev emulation is I<not> ABI compatible to libevent, you need |
2119 | to use the libev header file and library. |
2474 | to use the libev header file and library. |
2120 | |
2475 | |
2121 | =back |
2476 | =back |
2122 | |
2477 | |
2123 | =head1 C++ SUPPORT |
2478 | =head1 C++ SUPPORT |
2124 | |
2479 | |
2125 | Libev comes with some simplistic wrapper classes for C++ that mainly allow |
2480 | Libev comes with some simplistic wrapper classes for C++ that mainly allow |
2126 | you to use some convinience methods to start/stop watchers and also change |
2481 | you to use some convenience methods to start/stop watchers and also change |
2127 | the callback model to a model using method callbacks on objects. |
2482 | the callback model to a model using method callbacks on objects. |
2128 | |
2483 | |
2129 | To use it, |
2484 | To use it, |
2130 | |
2485 | |
2131 | #include <ev++.h> |
2486 | #include <ev++.h> |
2132 | |
2487 | |
2133 | This automatically includes F<ev.h> and puts all of its definitions (many |
2488 | This automatically includes F<ev.h> and puts all of its definitions (many |
2134 | of them macros) into the global namespace. All C++ specific things are |
2489 | of them macros) into the global namespace. All C++ specific things are |
2135 | put into the C<ev> namespace. It should support all the same embedding |
2490 | put into the C<ev> namespace. It should support all the same embedding |
2136 | options as F<ev.h>, most notably C<EV_MULTIPLICITY>. |
2491 | options as F<ev.h>, most notably C<EV_MULTIPLICITY>. |
… | |
… | |
2203 | your compiler is good :), then the method will be fully inlined into the |
2558 | your compiler is good :), then the method will be fully inlined into the |
2204 | thunking function, making it as fast as a direct C callback. |
2559 | thunking function, making it as fast as a direct C callback. |
2205 | |
2560 | |
2206 | Example: simple class declaration and watcher initialisation |
2561 | Example: simple class declaration and watcher initialisation |
2207 | |
2562 | |
2208 | struct myclass |
2563 | struct myclass |
2209 | { |
2564 | { |
2210 | void io_cb (ev::io &w, int revents) { } |
2565 | void io_cb (ev::io &w, int revents) { } |
2211 | } |
2566 | } |
2212 | |
2567 | |
2213 | myclass obj; |
2568 | myclass obj; |
2214 | ev::io iow; |
2569 | ev::io iow; |
2215 | iow.set <myclass, &myclass::io_cb> (&obj); |
2570 | iow.set <myclass, &myclass::io_cb> (&obj); |
2216 | |
2571 | |
2217 | =item w->set<function> (void *data = 0) |
2572 | =item w->set<function> (void *data = 0) |
2218 | |
2573 | |
2219 | Also sets a callback, but uses a static method or plain function as |
2574 | Also sets a callback, but uses a static method or plain function as |
2220 | callback. The optional C<data> argument will be stored in the watcher's |
2575 | callback. The optional C<data> argument will be stored in the watcher's |
… | |
… | |
2224 | |
2579 | |
2225 | See the method-C<set> above for more details. |
2580 | See the method-C<set> above for more details. |
2226 | |
2581 | |
2227 | Example: |
2582 | Example: |
2228 | |
2583 | |
2229 | static void io_cb (ev::io &w, int revents) { } |
2584 | static void io_cb (ev::io &w, int revents) { } |
2230 | iow.set <io_cb> (); |
2585 | iow.set <io_cb> (); |
2231 | |
2586 | |
2232 | =item w->set (struct ev_loop *) |
2587 | =item w->set (struct ev_loop *) |
2233 | |
2588 | |
2234 | Associates a different C<struct ev_loop> with this watcher. You can only |
2589 | Associates a different C<struct ev_loop> with this watcher. You can only |
2235 | do this when the watcher is inactive (and not pending either). |
2590 | do this when the watcher is inactive (and not pending either). |
2236 | |
2591 | |
2237 | =item w->set ([args]) |
2592 | =item w->set ([arguments]) |
2238 | |
2593 | |
2239 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
2594 | Basically the same as C<ev_TYPE_set>, with the same arguments. Must be |
2240 | called at least once. Unlike the C counterpart, an active watcher gets |
2595 | called at least once. Unlike the C counterpart, an active watcher gets |
2241 | automatically stopped and restarted when reconfiguring it with this |
2596 | automatically stopped and restarted when reconfiguring it with this |
2242 | method. |
2597 | method. |
2243 | |
2598 | |
2244 | =item w->start () |
2599 | =item w->start () |
… | |
… | |
2268 | =back |
2623 | =back |
2269 | |
2624 | |
2270 | Example: Define a class with an IO and idle watcher, start one of them in |
2625 | Example: Define a class with an IO and idle watcher, start one of them in |
2271 | the constructor. |
2626 | the constructor. |
2272 | |
2627 | |
2273 | class myclass |
2628 | class myclass |
2274 | { |
2629 | { |
2275 | ev_io io; void io_cb (ev::io &w, int revents); |
2630 | ev::io io; void io_cb (ev::io &w, int revents); |
2276 | ev_idle idle void idle_cb (ev::idle &w, int revents); |
2631 | ev:idle idle void idle_cb (ev::idle &w, int revents); |
2277 | |
2632 | |
2278 | myclass (); |
2633 | myclass (int fd) |
2279 | } |
2634 | { |
2280 | |
|
|
2281 | myclass::myclass (int fd) |
|
|
2282 | { |
|
|
2283 | io .set <myclass, &myclass::io_cb > (this); |
2635 | io .set <myclass, &myclass::io_cb > (this); |
2284 | idle.set <myclass, &myclass::idle_cb> (this); |
2636 | idle.set <myclass, &myclass::idle_cb> (this); |
2285 | |
2637 | |
2286 | io.start (fd, ev::READ); |
2638 | io.start (fd, ev::READ); |
|
|
2639 | } |
2287 | } |
2640 | }; |
|
|
2641 | |
|
|
2642 | |
|
|
2643 | =head1 OTHER LANGUAGE BINDINGS |
|
|
2644 | |
|
|
2645 | Libev does not offer other language bindings itself, but bindings for a |
|
|
2646 | number of languages exist in the form of third-party packages. If you know |
|
|
2647 | any interesting language binding in addition to the ones listed here, drop |
|
|
2648 | me a note. |
|
|
2649 | |
|
|
2650 | =over 4 |
|
|
2651 | |
|
|
2652 | =item Perl |
|
|
2653 | |
|
|
2654 | The EV module implements the full libev API and is actually used to test |
|
|
2655 | libev. EV is developed together with libev. Apart from the EV core module, |
|
|
2656 | there are additional modules that implement libev-compatible interfaces |
|
|
2657 | to C<libadns> (C<EV::ADNS>), C<Net::SNMP> (C<Net::SNMP::EV>) and the |
|
|
2658 | C<libglib> event core (C<Glib::EV> and C<EV::Glib>). |
|
|
2659 | |
|
|
2660 | It can be found and installed via CPAN, its homepage is at |
|
|
2661 | L<http://software.schmorp.de/pkg/EV>. |
|
|
2662 | |
|
|
2663 | =item Python |
|
|
2664 | |
|
|
2665 | Python bindings can be found at L<http://code.google.com/p/pyev/>. It |
|
|
2666 | seems to be quite complete and well-documented. Note, however, that the |
|
|
2667 | patch they require for libev is outright dangerous as it breaks the ABI |
|
|
2668 | for everybody else, and therefore, should never be applied in an installed |
|
|
2669 | libev (if python requires an incompatible ABI then it needs to embed |
|
|
2670 | libev). |
|
|
2671 | |
|
|
2672 | =item Ruby |
|
|
2673 | |
|
|
2674 | Tony Arcieri has written a ruby extension that offers access to a subset |
|
|
2675 | of the libev API and adds file handle abstractions, asynchronous DNS and |
|
|
2676 | more on top of it. It can be found via gem servers. Its homepage is at |
|
|
2677 | L<http://rev.rubyforge.org/>. |
|
|
2678 | |
|
|
2679 | =item D |
|
|
2680 | |
|
|
2681 | Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to |
|
|
2682 | be found at L<http://proj.llucax.com.ar/wiki/evd>. |
|
|
2683 | |
|
|
2684 | =back |
2288 | |
2685 | |
2289 | |
2686 | |
2290 | =head1 MACRO MAGIC |
2687 | =head1 MACRO MAGIC |
2291 | |
2688 | |
2292 | Libev can be compiled with a variety of options, the most fundamantal |
2689 | Libev can be compiled with a variety of options, the most fundamental |
2293 | of which is C<EV_MULTIPLICITY>. This option determines whether (most) |
2690 | of which is C<EV_MULTIPLICITY>. This option determines whether (most) |
2294 | functions and callbacks have an initial C<struct ev_loop *> argument. |
2691 | functions and callbacks have an initial C<struct ev_loop *> argument. |
2295 | |
2692 | |
2296 | To make it easier to write programs that cope with either variant, the |
2693 | To make it easier to write programs that cope with either variant, the |
2297 | following macros are defined: |
2694 | following macros are defined: |
… | |
… | |
2302 | |
2699 | |
2303 | This provides the loop I<argument> for functions, if one is required ("ev |
2700 | This provides the loop I<argument> for functions, if one is required ("ev |
2304 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
2701 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
2305 | C<EV_A_> is used when other arguments are following. Example: |
2702 | C<EV_A_> is used when other arguments are following. Example: |
2306 | |
2703 | |
2307 | ev_unref (EV_A); |
2704 | ev_unref (EV_A); |
2308 | ev_timer_add (EV_A_ watcher); |
2705 | ev_timer_add (EV_A_ watcher); |
2309 | ev_loop (EV_A_ 0); |
2706 | ev_loop (EV_A_ 0); |
2310 | |
2707 | |
2311 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
2708 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
2312 | which is often provided by the following macro. |
2709 | which is often provided by the following macro. |
2313 | |
2710 | |
2314 | =item C<EV_P>, C<EV_P_> |
2711 | =item C<EV_P>, C<EV_P_> |
2315 | |
2712 | |
2316 | This provides the loop I<parameter> for functions, if one is required ("ev |
2713 | This provides the loop I<parameter> for functions, if one is required ("ev |
2317 | loop parameter"). The C<EV_P> form is used when this is the sole parameter, |
2714 | loop parameter"). The C<EV_P> form is used when this is the sole parameter, |
2318 | C<EV_P_> is used when other parameters are following. Example: |
2715 | C<EV_P_> is used when other parameters are following. Example: |
2319 | |
2716 | |
2320 | // this is how ev_unref is being declared |
2717 | // this is how ev_unref is being declared |
2321 | static void ev_unref (EV_P); |
2718 | static void ev_unref (EV_P); |
2322 | |
2719 | |
2323 | // this is how you can declare your typical callback |
2720 | // this is how you can declare your typical callback |
2324 | static void cb (EV_P_ ev_timer *w, int revents) |
2721 | static void cb (EV_P_ ev_timer *w, int revents) |
2325 | |
2722 | |
2326 | It declares a parameter C<loop> of type C<struct ev_loop *>, quite |
2723 | It declares a parameter C<loop> of type C<struct ev_loop *>, quite |
2327 | suitable for use with C<EV_A>. |
2724 | suitable for use with C<EV_A>. |
2328 | |
2725 | |
2329 | =item C<EV_DEFAULT>, C<EV_DEFAULT_> |
2726 | =item C<EV_DEFAULT>, C<EV_DEFAULT_> |
2330 | |
2727 | |
2331 | Similar to the other two macros, this gives you the value of the default |
2728 | Similar to the other two macros, this gives you the value of the default |
2332 | loop, if multiple loops are supported ("ev loop default"). |
2729 | loop, if multiple loops are supported ("ev loop default"). |
|
|
2730 | |
|
|
2731 | =item C<EV_DEFAULT_UC>, C<EV_DEFAULT_UC_> |
|
|
2732 | |
|
|
2733 | Usage identical to C<EV_DEFAULT> and C<EV_DEFAULT_>, but requires that the |
|
|
2734 | default loop has been initialised (C<UC> == unchecked). Their behaviour |
|
|
2735 | is undefined when the default loop has not been initialised by a previous |
|
|
2736 | execution of C<EV_DEFAULT>, C<EV_DEFAULT_> or C<ev_default_init (...)>. |
|
|
2737 | |
|
|
2738 | It is often prudent to use C<EV_DEFAULT> when initialising the first |
|
|
2739 | watcher in a function but use C<EV_DEFAULT_UC> afterwards. |
2333 | |
2740 | |
2334 | =back |
2741 | =back |
2335 | |
2742 | |
2336 | Example: Declare and initialise a check watcher, utilising the above |
2743 | Example: Declare and initialise a check watcher, utilising the above |
2337 | macros so it will work regardless of whether multiple loops are supported |
2744 | macros so it will work regardless of whether multiple loops are supported |
2338 | or not. |
2745 | or not. |
2339 | |
2746 | |
2340 | static void |
2747 | static void |
2341 | check_cb (EV_P_ ev_timer *w, int revents) |
2748 | check_cb (EV_P_ ev_timer *w, int revents) |
2342 | { |
2749 | { |
2343 | ev_check_stop (EV_A_ w); |
2750 | ev_check_stop (EV_A_ w); |
2344 | } |
2751 | } |
2345 | |
2752 | |
2346 | ev_check check; |
2753 | ev_check check; |
2347 | ev_check_init (&check, check_cb); |
2754 | ev_check_init (&check, check_cb); |
2348 | ev_check_start (EV_DEFAULT_ &check); |
2755 | ev_check_start (EV_DEFAULT_ &check); |
2349 | ev_loop (EV_DEFAULT_ 0); |
2756 | ev_loop (EV_DEFAULT_ 0); |
2350 | |
2757 | |
2351 | =head1 EMBEDDING |
2758 | =head1 EMBEDDING |
2352 | |
2759 | |
2353 | Libev can (and often is) directly embedded into host |
2760 | Libev can (and often is) directly embedded into host |
2354 | applications. Examples of applications that embed it include the Deliantra |
2761 | applications. Examples of applications that embed it include the Deliantra |
… | |
… | |
2361 | libev somewhere in your source tree). |
2768 | libev somewhere in your source tree). |
2362 | |
2769 | |
2363 | =head2 FILESETS |
2770 | =head2 FILESETS |
2364 | |
2771 | |
2365 | Depending on what features you need you need to include one or more sets of files |
2772 | Depending on what features you need you need to include one or more sets of files |
2366 | in your app. |
2773 | in your application. |
2367 | |
2774 | |
2368 | =head3 CORE EVENT LOOP |
2775 | =head3 CORE EVENT LOOP |
2369 | |
2776 | |
2370 | To include only the libev core (all the C<ev_*> functions), with manual |
2777 | To include only the libev core (all the C<ev_*> functions), with manual |
2371 | configuration (no autoconf): |
2778 | configuration (no autoconf): |
2372 | |
2779 | |
2373 | #define EV_STANDALONE 1 |
2780 | #define EV_STANDALONE 1 |
2374 | #include "ev.c" |
2781 | #include "ev.c" |
2375 | |
2782 | |
2376 | This will automatically include F<ev.h>, too, and should be done in a |
2783 | This will automatically include F<ev.h>, too, and should be done in a |
2377 | single C source file only to provide the function implementations. To use |
2784 | single C source file only to provide the function implementations. To use |
2378 | it, do the same for F<ev.h> in all files wishing to use this API (best |
2785 | it, do the same for F<ev.h> in all files wishing to use this API (best |
2379 | done by writing a wrapper around F<ev.h> that you can include instead and |
2786 | done by writing a wrapper around F<ev.h> that you can include instead and |
2380 | where you can put other configuration options): |
2787 | where you can put other configuration options): |
2381 | |
2788 | |
2382 | #define EV_STANDALONE 1 |
2789 | #define EV_STANDALONE 1 |
2383 | #include "ev.h" |
2790 | #include "ev.h" |
2384 | |
2791 | |
2385 | Both header files and implementation files can be compiled with a C++ |
2792 | Both header files and implementation files can be compiled with a C++ |
2386 | compiler (at least, thats a stated goal, and breakage will be treated |
2793 | compiler (at least, thats a stated goal, and breakage will be treated |
2387 | as a bug). |
2794 | as a bug). |
2388 | |
2795 | |
2389 | You need the following files in your source tree, or in a directory |
2796 | You need the following files in your source tree, or in a directory |
2390 | in your include path (e.g. in libev/ when using -Ilibev): |
2797 | in your include path (e.g. in libev/ when using -Ilibev): |
2391 | |
2798 | |
2392 | ev.h |
2799 | ev.h |
2393 | ev.c |
2800 | ev.c |
2394 | ev_vars.h |
2801 | ev_vars.h |
2395 | ev_wrap.h |
2802 | ev_wrap.h |
2396 | |
2803 | |
2397 | ev_win32.c required on win32 platforms only |
2804 | ev_win32.c required on win32 platforms only |
2398 | |
2805 | |
2399 | ev_select.c only when select backend is enabled (which is enabled by default) |
2806 | ev_select.c only when select backend is enabled (which is enabled by default) |
2400 | ev_poll.c only when poll backend is enabled (disabled by default) |
2807 | ev_poll.c only when poll backend is enabled (disabled by default) |
2401 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
2808 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
2402 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
2809 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
2403 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
2810 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
2404 | |
2811 | |
2405 | F<ev.c> includes the backend files directly when enabled, so you only need |
2812 | F<ev.c> includes the backend files directly when enabled, so you only need |
2406 | to compile this single file. |
2813 | to compile this single file. |
2407 | |
2814 | |
2408 | =head3 LIBEVENT COMPATIBILITY API |
2815 | =head3 LIBEVENT COMPATIBILITY API |
2409 | |
2816 | |
2410 | To include the libevent compatibility API, also include: |
2817 | To include the libevent compatibility API, also include: |
2411 | |
2818 | |
2412 | #include "event.c" |
2819 | #include "event.c" |
2413 | |
2820 | |
2414 | in the file including F<ev.c>, and: |
2821 | in the file including F<ev.c>, and: |
2415 | |
2822 | |
2416 | #include "event.h" |
2823 | #include "event.h" |
2417 | |
2824 | |
2418 | in the files that want to use the libevent API. This also includes F<ev.h>. |
2825 | in the files that want to use the libevent API. This also includes F<ev.h>. |
2419 | |
2826 | |
2420 | You need the following additional files for this: |
2827 | You need the following additional files for this: |
2421 | |
2828 | |
2422 | event.h |
2829 | event.h |
2423 | event.c |
2830 | event.c |
2424 | |
2831 | |
2425 | =head3 AUTOCONF SUPPORT |
2832 | =head3 AUTOCONF SUPPORT |
2426 | |
2833 | |
2427 | Instead of using C<EV_STANDALONE=1> and providing your config in |
2834 | Instead of using C<EV_STANDALONE=1> and providing your configuration in |
2428 | whatever way you want, you can also C<m4_include([libev.m4])> in your |
2835 | whatever way you want, you can also C<m4_include([libev.m4])> in your |
2429 | F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then |
2836 | F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then |
2430 | include F<config.h> and configure itself accordingly. |
2837 | include F<config.h> and configure itself accordingly. |
2431 | |
2838 | |
2432 | For this of course you need the m4 file: |
2839 | For this of course you need the m4 file: |
2433 | |
2840 | |
2434 | libev.m4 |
2841 | libev.m4 |
2435 | |
2842 | |
2436 | =head2 PREPROCESSOR SYMBOLS/MACROS |
2843 | =head2 PREPROCESSOR SYMBOLS/MACROS |
2437 | |
2844 | |
2438 | Libev can be configured via a variety of preprocessor symbols you have to define |
2845 | Libev can be configured via a variety of preprocessor symbols you have to |
2439 | before including any of its files. The default is not to build for multiplicity |
2846 | define before including any of its files. The default in the absence of |
2440 | and only include the select backend. |
2847 | autoconf is noted for every option. |
2441 | |
2848 | |
2442 | =over 4 |
2849 | =over 4 |
2443 | |
2850 | |
2444 | =item EV_STANDALONE |
2851 | =item EV_STANDALONE |
2445 | |
2852 | |
… | |
… | |
2450 | F<event.h> that are not directly supported by the libev core alone. |
2857 | F<event.h> that are not directly supported by the libev core alone. |
2451 | |
2858 | |
2452 | =item EV_USE_MONOTONIC |
2859 | =item EV_USE_MONOTONIC |
2453 | |
2860 | |
2454 | If defined to be C<1>, libev will try to detect the availability of the |
2861 | If defined to be C<1>, libev will try to detect the availability of the |
2455 | monotonic clock option at both compiletime and runtime. Otherwise no use |
2862 | monotonic clock option at both compile time and runtime. Otherwise no use |
2456 | of the monotonic clock option will be attempted. If you enable this, you |
2863 | of the monotonic clock option will be attempted. If you enable this, you |
2457 | usually have to link against librt or something similar. Enabling it when |
2864 | usually have to link against librt or something similar. Enabling it when |
2458 | the functionality isn't available is safe, though, although you have |
2865 | the functionality isn't available is safe, though, although you have |
2459 | to make sure you link against any libraries where the C<clock_gettime> |
2866 | to make sure you link against any libraries where the C<clock_gettime> |
2460 | function is hiding in (often F<-lrt>). |
2867 | function is hiding in (often F<-lrt>). |
2461 | |
2868 | |
2462 | =item EV_USE_REALTIME |
2869 | =item EV_USE_REALTIME |
2463 | |
2870 | |
2464 | If defined to be C<1>, libev will try to detect the availability of the |
2871 | If defined to be C<1>, libev will try to detect the availability of the |
2465 | realtime clock option at compiletime (and assume its availability at |
2872 | real-time clock option at compile time (and assume its availability at |
2466 | runtime if successful). Otherwise no use of the realtime clock option will |
2873 | runtime if successful). Otherwise no use of the real-time clock option will |
2467 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
2874 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
2468 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See the |
2875 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See the |
2469 | note about libraries in the description of C<EV_USE_MONOTONIC>, though. |
2876 | note about libraries in the description of C<EV_USE_MONOTONIC>, though. |
2470 | |
2877 | |
2471 | =item EV_USE_NANOSLEEP |
2878 | =item EV_USE_NANOSLEEP |
2472 | |
2879 | |
2473 | If defined to be C<1>, libev will assume that C<nanosleep ()> is available |
2880 | If defined to be C<1>, libev will assume that C<nanosleep ()> is available |
2474 | and will use it for delays. Otherwise it will use C<select ()>. |
2881 | and will use it for delays. Otherwise it will use C<select ()>. |
2475 | |
2882 | |
|
|
2883 | =item EV_USE_EVENTFD |
|
|
2884 | |
|
|
2885 | If defined to be C<1>, then libev will assume that C<eventfd ()> is |
|
|
2886 | available and will probe for kernel support at runtime. This will improve |
|
|
2887 | C<ev_signal> and C<ev_async> performance and reduce resource consumption. |
|
|
2888 | If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc |
|
|
2889 | 2.7 or newer, otherwise disabled. |
|
|
2890 | |
2476 | =item EV_USE_SELECT |
2891 | =item EV_USE_SELECT |
2477 | |
2892 | |
2478 | If undefined or defined to be C<1>, libev will compile in support for the |
2893 | If undefined or defined to be C<1>, libev will compile in support for the |
2479 | C<select>(2) backend. No attempt at autodetection will be done: if no |
2894 | C<select>(2) backend. No attempt at auto-detection will be done: if no |
2480 | other method takes over, select will be it. Otherwise the select backend |
2895 | other method takes over, select will be it. Otherwise the select backend |
2481 | will not be compiled in. |
2896 | will not be compiled in. |
2482 | |
2897 | |
2483 | =item EV_SELECT_USE_FD_SET |
2898 | =item EV_SELECT_USE_FD_SET |
2484 | |
2899 | |
2485 | If defined to C<1>, then the select backend will use the system C<fd_set> |
2900 | If defined to C<1>, then the select backend will use the system C<fd_set> |
2486 | structure. This is useful if libev doesn't compile due to a missing |
2901 | structure. This is useful if libev doesn't compile due to a missing |
2487 | C<NFDBITS> or C<fd_mask> definition or it misguesses the bitset layout on |
2902 | C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout on |
2488 | exotic systems. This usually limits the range of file descriptors to some |
2903 | exotic systems. This usually limits the range of file descriptors to some |
2489 | low limit such as 1024 or might have other limitations (winsocket only |
2904 | low limit such as 1024 or might have other limitations (winsocket only |
2490 | allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might |
2905 | allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might |
2491 | influence the size of the C<fd_set> used. |
2906 | influence the size of the C<fd_set> used. |
2492 | |
2907 | |
… | |
… | |
2516 | |
2931 | |
2517 | =item EV_USE_EPOLL |
2932 | =item EV_USE_EPOLL |
2518 | |
2933 | |
2519 | If defined to be C<1>, libev will compile in support for the Linux |
2934 | If defined to be C<1>, libev will compile in support for the Linux |
2520 | C<epoll>(7) backend. Its availability will be detected at runtime, |
2935 | C<epoll>(7) backend. Its availability will be detected at runtime, |
2521 | otherwise another method will be used as fallback. This is the |
2936 | otherwise another method will be used as fallback. This is the preferred |
2522 | preferred backend for GNU/Linux systems. |
2937 | backend for GNU/Linux systems. If undefined, it will be enabled if the |
|
|
2938 | headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
2523 | |
2939 | |
2524 | =item EV_USE_KQUEUE |
2940 | =item EV_USE_KQUEUE |
2525 | |
2941 | |
2526 | If defined to be C<1>, libev will compile in support for the BSD style |
2942 | If defined to be C<1>, libev will compile in support for the BSD style |
2527 | C<kqueue>(2) backend. Its actual availability will be detected at runtime, |
2943 | C<kqueue>(2) backend. Its actual availability will be detected at runtime, |
… | |
… | |
2540 | otherwise another method will be used as fallback. This is the preferred |
2956 | otherwise another method will be used as fallback. This is the preferred |
2541 | backend for Solaris 10 systems. |
2957 | backend for Solaris 10 systems. |
2542 | |
2958 | |
2543 | =item EV_USE_DEVPOLL |
2959 | =item EV_USE_DEVPOLL |
2544 | |
2960 | |
2545 | reserved for future expansion, works like the USE symbols above. |
2961 | Reserved for future expansion, works like the USE symbols above. |
2546 | |
2962 | |
2547 | =item EV_USE_INOTIFY |
2963 | =item EV_USE_INOTIFY |
2548 | |
2964 | |
2549 | If defined to be C<1>, libev will compile in support for the Linux inotify |
2965 | If defined to be C<1>, libev will compile in support for the Linux inotify |
2550 | interface to speed up C<ev_stat> watchers. Its actual availability will |
2966 | interface to speed up C<ev_stat> watchers. Its actual availability will |
2551 | be detected at runtime. |
2967 | be detected at runtime. If undefined, it will be enabled if the headers |
|
|
2968 | indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
|
|
2969 | |
|
|
2970 | =item EV_ATOMIC_T |
|
|
2971 | |
|
|
2972 | Libev requires an integer type (suitable for storing C<0> or C<1>) whose |
|
|
2973 | access is atomic with respect to other threads or signal contexts. No such |
|
|
2974 | type is easily found in the C language, so you can provide your own type |
|
|
2975 | that you know is safe for your purposes. It is used both for signal handler "locking" |
|
|
2976 | as well as for signal and thread safety in C<ev_async> watchers. |
|
|
2977 | |
|
|
2978 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
|
|
2979 | (from F<signal.h>), which is usually good enough on most platforms. |
2552 | |
2980 | |
2553 | =item EV_H |
2981 | =item EV_H |
2554 | |
2982 | |
2555 | The name of the F<ev.h> header file used to include it. The default if |
2983 | The name of the F<ev.h> header file used to include it. The default if |
2556 | undefined is C<"ev.h"> in F<event.h> and F<ev.c>. This can be used to |
2984 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
2557 | virtually rename the F<ev.h> header file in case of conflicts. |
2985 | used to virtually rename the F<ev.h> header file in case of conflicts. |
2558 | |
2986 | |
2559 | =item EV_CONFIG_H |
2987 | =item EV_CONFIG_H |
2560 | |
2988 | |
2561 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
2989 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
2562 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
2990 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
2563 | C<EV_H>, above. |
2991 | C<EV_H>, above. |
2564 | |
2992 | |
2565 | =item EV_EVENT_H |
2993 | =item EV_EVENT_H |
2566 | |
2994 | |
2567 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
2995 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
2568 | of how the F<event.h> header can be found, the dfeault is C<"event.h">. |
2996 | of how the F<event.h> header can be found, the default is C<"event.h">. |
2569 | |
2997 | |
2570 | =item EV_PROTOTYPES |
2998 | =item EV_PROTOTYPES |
2571 | |
2999 | |
2572 | If defined to be C<0>, then F<ev.h> will not define any function |
3000 | If defined to be C<0>, then F<ev.h> will not define any function |
2573 | prototypes, but still define all the structs and other symbols. This is |
3001 | prototypes, but still define all the structs and other symbols. This is |
… | |
… | |
2594 | When doing priority-based operations, libev usually has to linearly search |
3022 | When doing priority-based operations, libev usually has to linearly search |
2595 | all the priorities, so having many of them (hundreds) uses a lot of space |
3023 | all the priorities, so having many of them (hundreds) uses a lot of space |
2596 | and time, so using the defaults of five priorities (-2 .. +2) is usually |
3024 | and time, so using the defaults of five priorities (-2 .. +2) is usually |
2597 | fine. |
3025 | fine. |
2598 | |
3026 | |
2599 | If your embedding app does not need any priorities, defining these both to |
3027 | If your embedding application does not need any priorities, defining these both to |
2600 | C<0> will save some memory and cpu. |
3028 | C<0> will save some memory and CPU. |
2601 | |
3029 | |
2602 | =item EV_PERIODIC_ENABLE |
3030 | =item EV_PERIODIC_ENABLE |
2603 | |
3031 | |
2604 | If undefined or defined to be C<1>, then periodic timers are supported. If |
3032 | If undefined or defined to be C<1>, then periodic timers are supported. If |
2605 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
3033 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
… | |
… | |
2624 | =item EV_FORK_ENABLE |
3052 | =item EV_FORK_ENABLE |
2625 | |
3053 | |
2626 | If undefined or defined to be C<1>, then fork watchers are supported. If |
3054 | If undefined or defined to be C<1>, then fork watchers are supported. If |
2627 | defined to be C<0>, then they are not. |
3055 | defined to be C<0>, then they are not. |
2628 | |
3056 | |
|
|
3057 | =item EV_ASYNC_ENABLE |
|
|
3058 | |
|
|
3059 | If undefined or defined to be C<1>, then async watchers are supported. If |
|
|
3060 | defined to be C<0>, then they are not. |
|
|
3061 | |
2629 | =item EV_MINIMAL |
3062 | =item EV_MINIMAL |
2630 | |
3063 | |
2631 | If you need to shave off some kilobytes of code at the expense of some |
3064 | If you need to shave off some kilobytes of code at the expense of some |
2632 | speed, define this symbol to C<1>. Currently only used for gcc to override |
3065 | speed, define this symbol to C<1>. Currently this is used to override some |
2633 | some inlining decisions, saves roughly 30% codesize of amd64. |
3066 | inlining decisions, saves roughly 30% code size on amd64. It also selects a |
|
|
3067 | much smaller 2-heap for timer management over the default 4-heap. |
2634 | |
3068 | |
2635 | =item EV_PID_HASHSIZE |
3069 | =item EV_PID_HASHSIZE |
2636 | |
3070 | |
2637 | C<ev_child> watchers use a small hash table to distribute workload by |
3071 | C<ev_child> watchers use a small hash table to distribute workload by |
2638 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
3072 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
… | |
… | |
2645 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
3079 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
2646 | usually more than enough. If you need to manage thousands of C<ev_stat> |
3080 | usually more than enough. If you need to manage thousands of C<ev_stat> |
2647 | watchers you might want to increase this value (I<must> be a power of |
3081 | watchers you might want to increase this value (I<must> be a power of |
2648 | two). |
3082 | two). |
2649 | |
3083 | |
|
|
3084 | =item EV_USE_4HEAP |
|
|
3085 | |
|
|
3086 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
|
|
3087 | timer and periodics heap, libev uses a 4-heap when this symbol is defined |
|
|
3088 | to C<1>. The 4-heap uses more complicated (longer) code but has |
|
|
3089 | noticeably faster performance with many (thousands) of watchers. |
|
|
3090 | |
|
|
3091 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
|
|
3092 | (disabled). |
|
|
3093 | |
|
|
3094 | =item EV_HEAP_CACHE_AT |
|
|
3095 | |
|
|
3096 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
|
|
3097 | timer and periodics heap, libev can cache the timestamp (I<at>) within |
|
|
3098 | the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>), |
|
|
3099 | which uses 8-12 bytes more per watcher and a few hundred bytes more code, |
|
|
3100 | but avoids random read accesses on heap changes. This improves performance |
|
|
3101 | noticeably with with many (hundreds) of watchers. |
|
|
3102 | |
|
|
3103 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
|
|
3104 | (disabled). |
|
|
3105 | |
|
|
3106 | =item EV_VERIFY |
|
|
3107 | |
|
|
3108 | Controls how much internal verification (see C<ev_loop_verify ()>) will |
|
|
3109 | be done: If set to C<0>, no internal verification code will be compiled |
|
|
3110 | in. If set to C<1>, then verification code will be compiled in, but not |
|
|
3111 | called. If set to C<2>, then the internal verification code will be |
|
|
3112 | called once per loop, which can slow down libev. If set to C<3>, then the |
|
|
3113 | verification code will be called very frequently, which will slow down |
|
|
3114 | libev considerably. |
|
|
3115 | |
|
|
3116 | The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be |
|
|
3117 | C<0.> |
|
|
3118 | |
2650 | =item EV_COMMON |
3119 | =item EV_COMMON |
2651 | |
3120 | |
2652 | By default, all watchers have a C<void *data> member. By redefining |
3121 | By default, all watchers have a C<void *data> member. By redefining |
2653 | this macro to a something else you can include more and other types of |
3122 | this macro to a something else you can include more and other types of |
2654 | members. You have to define it each time you include one of the files, |
3123 | members. You have to define it each time you include one of the files, |
2655 | though, and it must be identical each time. |
3124 | though, and it must be identical each time. |
2656 | |
3125 | |
2657 | For example, the perl EV module uses something like this: |
3126 | For example, the perl EV module uses something like this: |
2658 | |
3127 | |
2659 | #define EV_COMMON \ |
3128 | #define EV_COMMON \ |
2660 | SV *self; /* contains this struct */ \ |
3129 | SV *self; /* contains this struct */ \ |
2661 | SV *cb_sv, *fh /* note no trailing ";" */ |
3130 | SV *cb_sv, *fh /* note no trailing ";" */ |
2662 | |
3131 | |
2663 | =item EV_CB_DECLARE (type) |
3132 | =item EV_CB_DECLARE (type) |
2664 | |
3133 | |
2665 | =item EV_CB_INVOKE (watcher, revents) |
3134 | =item EV_CB_INVOKE (watcher, revents) |
2666 | |
3135 | |
… | |
… | |
2673 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
3142 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
2674 | method calls instead of plain function calls in C++. |
3143 | method calls instead of plain function calls in C++. |
2675 | |
3144 | |
2676 | =head2 EXPORTED API SYMBOLS |
3145 | =head2 EXPORTED API SYMBOLS |
2677 | |
3146 | |
2678 | If you need to re-export the API (e.g. via a dll) and you need a list of |
3147 | If you need to re-export the API (e.g. via a DLL) and you need a list of |
2679 | exported symbols, you can use the provided F<Symbol.*> files which list |
3148 | exported symbols, you can use the provided F<Symbol.*> files which list |
2680 | all public symbols, one per line: |
3149 | all public symbols, one per line: |
2681 | |
3150 | |
2682 | Symbols.ev for libev proper |
3151 | Symbols.ev for libev proper |
2683 | Symbols.event for the libevent emulation |
3152 | Symbols.event for the libevent emulation |
2684 | |
3153 | |
2685 | This can also be used to rename all public symbols to avoid clashes with |
3154 | This can also be used to rename all public symbols to avoid clashes with |
2686 | multiple versions of libev linked together (which is obviously bad in |
3155 | multiple versions of libev linked together (which is obviously bad in |
2687 | itself, but sometimes it is inconvinient to avoid this). |
3156 | itself, but sometimes it is inconvenient to avoid this). |
2688 | |
3157 | |
2689 | A sed command like this will create wrapper C<#define>'s that you need to |
3158 | A sed command like this will create wrapper C<#define>'s that you need to |
2690 | include before including F<ev.h>: |
3159 | include before including F<ev.h>: |
2691 | |
3160 | |
2692 | <Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h |
3161 | <Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h |
… | |
… | |
2709 | file. |
3178 | file. |
2710 | |
3179 | |
2711 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
3180 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
2712 | that everybody includes and which overrides some configure choices: |
3181 | that everybody includes and which overrides some configure choices: |
2713 | |
3182 | |
2714 | #define EV_MINIMAL 1 |
3183 | #define EV_MINIMAL 1 |
2715 | #define EV_USE_POLL 0 |
3184 | #define EV_USE_POLL 0 |
2716 | #define EV_MULTIPLICITY 0 |
3185 | #define EV_MULTIPLICITY 0 |
2717 | #define EV_PERIODIC_ENABLE 0 |
3186 | #define EV_PERIODIC_ENABLE 0 |
2718 | #define EV_STAT_ENABLE 0 |
3187 | #define EV_STAT_ENABLE 0 |
2719 | #define EV_FORK_ENABLE 0 |
3188 | #define EV_FORK_ENABLE 0 |
2720 | #define EV_CONFIG_H <config.h> |
3189 | #define EV_CONFIG_H <config.h> |
2721 | #define EV_MINPRI 0 |
3190 | #define EV_MINPRI 0 |
2722 | #define EV_MAXPRI 0 |
3191 | #define EV_MAXPRI 0 |
2723 | |
3192 | |
2724 | #include "ev++.h" |
3193 | #include "ev++.h" |
2725 | |
3194 | |
2726 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
3195 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
2727 | |
3196 | |
2728 | #include "ev_cpp.h" |
3197 | #include "ev_cpp.h" |
2729 | #include "ev.c" |
3198 | #include "ev.c" |
|
|
3199 | |
|
|
3200 | |
|
|
3201 | =head1 THREADS AND COROUTINES |
|
|
3202 | |
|
|
3203 | =head2 THREADS |
|
|
3204 | |
|
|
3205 | Libev itself is completely thread-safe, but it uses no locking. This |
|
|
3206 | means that you can use as many loops as you want in parallel, as long as |
|
|
3207 | only one thread ever calls into one libev function with the same loop |
|
|
3208 | parameter. |
|
|
3209 | |
|
|
3210 | Or put differently: calls with different loop parameters can be done in |
|
|
3211 | parallel from multiple threads, calls with the same loop parameter must be |
|
|
3212 | done serially (but can be done from different threads, as long as only one |
|
|
3213 | thread ever is inside a call at any point in time, e.g. by using a mutex |
|
|
3214 | per loop). |
|
|
3215 | |
|
|
3216 | If you want to know which design (one loop, locking, or multiple loops |
|
|
3217 | without or something else still) is best for your problem, then I cannot |
|
|
3218 | help you. I can give some generic advice however: |
|
|
3219 | |
|
|
3220 | =over 4 |
|
|
3221 | |
|
|
3222 | =item * most applications have a main thread: use the default libev loop |
|
|
3223 | in that thread, or create a separate thread running only the default loop. |
|
|
3224 | |
|
|
3225 | This helps integrating other libraries or software modules that use libev |
|
|
3226 | themselves and don't care/know about threading. |
|
|
3227 | |
|
|
3228 | =item * one loop per thread is usually a good model. |
|
|
3229 | |
|
|
3230 | Doing this is almost never wrong, sometimes a better-performance model |
|
|
3231 | exists, but it is always a good start. |
|
|
3232 | |
|
|
3233 | =item * other models exist, such as the leader/follower pattern, where one |
|
|
3234 | loop is handed through multiple threads in a kind of round-robin fashion. |
|
|
3235 | |
|
|
3236 | Choosing a model is hard - look around, learn, know that usually you can do |
|
|
3237 | better than you currently do :-) |
|
|
3238 | |
|
|
3239 | =item * often you need to talk to some other thread which blocks in the |
|
|
3240 | event loop - C<ev_async> watchers can be used to wake them up from other |
|
|
3241 | threads safely (or from signal contexts...). |
|
|
3242 | |
|
|
3243 | =back |
|
|
3244 | |
|
|
3245 | =head2 COROUTINES |
|
|
3246 | |
|
|
3247 | Libev is much more accommodating to coroutines ("cooperative threads"): |
|
|
3248 | libev fully supports nesting calls to it's functions from different |
|
|
3249 | coroutines (e.g. you can call C<ev_loop> on the same loop from two |
|
|
3250 | different coroutines and switch freely between both coroutines running the |
|
|
3251 | loop, as long as you don't confuse yourself). The only exception is that |
|
|
3252 | you must not do this from C<ev_periodic> reschedule callbacks. |
|
|
3253 | |
|
|
3254 | Care has been invested into making sure that libev does not keep local |
|
|
3255 | state inside C<ev_loop>, and other calls do not usually allow coroutine |
|
|
3256 | switches. |
2730 | |
3257 | |
2731 | |
3258 | |
2732 | =head1 COMPLEXITIES |
3259 | =head1 COMPLEXITIES |
2733 | |
3260 | |
2734 | In this section the complexities of (many of) the algorithms used inside |
3261 | In this section the complexities of (many of) the algorithms used inside |
… | |
… | |
2752 | =item Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers) |
3279 | =item Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers) |
2753 | |
3280 | |
2754 | That means that changing a timer costs less than removing/adding them |
3281 | That means that changing a timer costs less than removing/adding them |
2755 | as only the relative motion in the event queue has to be paid for. |
3282 | as only the relative motion in the event queue has to be paid for. |
2756 | |
3283 | |
2757 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
3284 | =item Starting io/check/prepare/idle/signal/child/fork/async watchers: O(1) |
2758 | |
3285 | |
2759 | These just add the watcher into an array or at the head of a list. |
3286 | These just add the watcher into an array or at the head of a list. |
2760 | |
3287 | |
2761 | =item Stopping check/prepare/idle watchers: O(1) |
3288 | =item Stopping check/prepare/idle/fork/async watchers: O(1) |
2762 | |
3289 | |
2763 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
3290 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2764 | |
3291 | |
2765 | These watchers are stored in lists then need to be walked to find the |
3292 | These watchers are stored in lists then need to be walked to find the |
2766 | correct watcher to remove. The lists are usually short (you don't usually |
3293 | correct watcher to remove. The lists are usually short (you don't usually |
2767 | have many watchers waiting for the same fd or signal). |
3294 | have many watchers waiting for the same fd or signal). |
2768 | |
3295 | |
2769 | =item Finding the next timer in each loop iteration: O(1) |
3296 | =item Finding the next timer in each loop iteration: O(1) |
2770 | |
3297 | |
2771 | By virtue of using a binary heap, the next timer is always found at the |
3298 | By virtue of using a binary or 4-heap, the next timer is always found at a |
2772 | beginning of the storage array. |
3299 | fixed position in the storage array. |
2773 | |
3300 | |
2774 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
3301 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2775 | |
3302 | |
2776 | A change means an I/O watcher gets started or stopped, which requires |
3303 | A change means an I/O watcher gets started or stopped, which requires |
2777 | libev to recalculate its status (and possibly tell the kernel, depending |
3304 | libev to recalculate its status (and possibly tell the kernel, depending |
2778 | on backend and wether C<ev_io_set> was used). |
3305 | on backend and whether C<ev_io_set> was used). |
2779 | |
3306 | |
2780 | =item Activating one watcher (putting it into the pending state): O(1) |
3307 | =item Activating one watcher (putting it into the pending state): O(1) |
2781 | |
3308 | |
2782 | =item Priority handling: O(number_of_priorities) |
3309 | =item Priority handling: O(number_of_priorities) |
2783 | |
3310 | |
2784 | Priorities are implemented by allocating some space for each |
3311 | Priorities are implemented by allocating some space for each |
2785 | priority. When doing priority-based operations, libev usually has to |
3312 | priority. When doing priority-based operations, libev usually has to |
2786 | linearly search all the priorities, but starting/stopping and activating |
3313 | linearly search all the priorities, but starting/stopping and activating |
2787 | watchers becomes O(1) w.r.t. prioritiy handling. |
3314 | watchers becomes O(1) w.r.t. priority handling. |
|
|
3315 | |
|
|
3316 | =item Sending an ev_async: O(1) |
|
|
3317 | |
|
|
3318 | =item Processing ev_async_send: O(number_of_async_watchers) |
|
|
3319 | |
|
|
3320 | =item Processing signals: O(max_signal_number) |
|
|
3321 | |
|
|
3322 | Sending involves a system call I<iff> there were no other C<ev_async_send> |
|
|
3323 | calls in the current loop iteration. Checking for async and signal events |
|
|
3324 | involves iterating over all running async watchers or all signal numbers. |
2788 | |
3325 | |
2789 | =back |
3326 | =back |
2790 | |
3327 | |
2791 | |
3328 | |
2792 | =head1 Win32 platform limitations and workarounds |
3329 | =head1 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS |
2793 | |
3330 | |
2794 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
3331 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
2795 | requires, and its I/O model is fundamentally incompatible with the POSIX |
3332 | requires, and its I/O model is fundamentally incompatible with the POSIX |
2796 | model. Libev still offers limited functionality on this platform in |
3333 | model. Libev still offers limited functionality on this platform in |
2797 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
3334 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
2798 | descriptors. This only applies when using Win32 natively, not when using |
3335 | descriptors. This only applies when using Win32 natively, not when using |
2799 | e.g. cygwin. |
3336 | e.g. cygwin. |
2800 | |
3337 | |
|
|
3338 | Lifting these limitations would basically require the full |
|
|
3339 | re-implementation of the I/O system. If you are into these kinds of |
|
|
3340 | things, then note that glib does exactly that for you in a very portable |
|
|
3341 | way (note also that glib is the slowest event library known to man). |
|
|
3342 | |
2801 | There is no supported compilation method available on windows except |
3343 | There is no supported compilation method available on windows except |
2802 | embedding it into other applications. |
3344 | embedding it into other applications. |
2803 | |
3345 | |
|
|
3346 | Not a libev limitation but worth mentioning: windows apparently doesn't |
|
|
3347 | accept large writes: instead of resulting in a partial write, windows will |
|
|
3348 | either accept everything or return C<ENOBUFS> if the buffer is too large, |
|
|
3349 | so make sure you only write small amounts into your sockets (less than a |
|
|
3350 | megabyte seems safe, but thsi apparently depends on the amount of memory |
|
|
3351 | available). |
|
|
3352 | |
2804 | Due to the many, low, and arbitrary limits on the win32 platform and the |
3353 | Due to the many, low, and arbitrary limits on the win32 platform and |
2805 | abysmal performance of winsockets, using a large number of sockets is not |
3354 | the abysmal performance of winsockets, using a large number of sockets |
2806 | recommended (and not reasonable). If your program needs to use more than |
3355 | is not recommended (and not reasonable). If your program needs to use |
2807 | a hundred or so sockets, then likely it needs to use a totally different |
3356 | more than a hundred or so sockets, then likely it needs to use a totally |
2808 | implementation for windows, as libev offers the POSIX model, which cannot |
3357 | different implementation for windows, as libev offers the POSIX readiness |
2809 | be implemented efficiently on windows (microsoft monopoly games). |
3358 | notification model, which cannot be implemented efficiently on windows |
|
|
3359 | (Microsoft monopoly games). |
|
|
3360 | |
|
|
3361 | A typical way to use libev under windows is to embed it (see the embedding |
|
|
3362 | section for details) and use the following F<evwrap.h> header file instead |
|
|
3363 | of F<ev.h>: |
|
|
3364 | |
|
|
3365 | #define EV_STANDALONE /* keeps ev from requiring config.h */ |
|
|
3366 | #define EV_SELECT_IS_WINSOCKET 1 /* configure libev for windows select */ |
|
|
3367 | |
|
|
3368 | #include "ev.h" |
|
|
3369 | |
|
|
3370 | And compile the following F<evwrap.c> file into your project (make sure |
|
|
3371 | you do I<not> compile the F<ev.c> or any other embedded soruce files!): |
|
|
3372 | |
|
|
3373 | #include "evwrap.h" |
|
|
3374 | #include "ev.c" |
2810 | |
3375 | |
2811 | =over 4 |
3376 | =over 4 |
2812 | |
3377 | |
2813 | =item The winsocket select function |
3378 | =item The winsocket select function |
2814 | |
3379 | |
2815 | The winsocket C<select> function doesn't follow POSIX in that it requires |
3380 | The winsocket C<select> function doesn't follow POSIX in that it |
2816 | socket I<handles> and not socket I<file descriptors>. This makes select |
3381 | requires socket I<handles> and not socket I<file descriptors> (it is |
2817 | very inefficient, and also requires a mapping from file descriptors |
3382 | also extremely buggy). This makes select very inefficient, and also |
2818 | to socket handles. See the discussion of the C<EV_SELECT_USE_FD_SET>, |
3383 | requires a mapping from file descriptors to socket handles (the Microsoft |
2819 | C<EV_SELECT_IS_WINSOCKET> and C<EV_FD_TO_WIN32_HANDLE> preprocessor |
3384 | C runtime provides the function C<_open_osfhandle> for this). See the |
2820 | symbols for more info. |
3385 | discussion of the C<EV_SELECT_USE_FD_SET>, C<EV_SELECT_IS_WINSOCKET> and |
|
|
3386 | C<EV_FD_TO_WIN32_HANDLE> preprocessor symbols for more info. |
2821 | |
3387 | |
2822 | The configuration for a "naked" win32 using the microsoft runtime |
3388 | The configuration for a "naked" win32 using the Microsoft runtime |
2823 | libraries and raw winsocket select is: |
3389 | libraries and raw winsocket select is: |
2824 | |
3390 | |
2825 | #define EV_USE_SELECT 1 |
3391 | #define EV_USE_SELECT 1 |
2826 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
3392 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
2827 | |
3393 | |
2828 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
3394 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
2829 | complexity in the O(n²) range when using win32. |
3395 | complexity in the O(n²) range when using win32. |
2830 | |
3396 | |
2831 | =item Limited number of file descriptors |
3397 | =item Limited number of file descriptors |
2832 | |
3398 | |
2833 | Windows has numerous arbitrary (and low) limits on things. Early versions |
3399 | Windows has numerous arbitrary (and low) limits on things. |
2834 | of winsocket's select only supported waiting for a max. of C<64> handles |
3400 | |
|
|
3401 | Early versions of winsocket's select only supported waiting for a maximum |
2835 | (probably owning to the fact that all windows kernels can only wait for |
3402 | of C<64> handles (probably owning to the fact that all windows kernels |
2836 | C<64> things at the same time internally; microsoft recommends spawning a |
3403 | can only wait for C<64> things at the same time internally; Microsoft |
2837 | chain of threads and wait for 63 handles and the previous thread in each). |
3404 | recommends spawning a chain of threads and wait for 63 handles and the |
|
|
3405 | previous thread in each. Great). |
2838 | |
3406 | |
2839 | Newer versions support more handles, but you need to define C<FD_SETSIZE> |
3407 | Newer versions support more handles, but you need to define C<FD_SETSIZE> |
2840 | to some high number (e.g. C<2048>) before compiling the winsocket select |
3408 | to some high number (e.g. C<2048>) before compiling the winsocket select |
2841 | call (which might be in libev or elsewhere, for example, perl does its own |
3409 | call (which might be in libev or elsewhere, for example, perl does its own |
2842 | select emulation on windows). |
3410 | select emulation on windows). |
2843 | |
3411 | |
2844 | Another limit is the number of file descriptors in the microsoft runtime |
3412 | Another limit is the number of file descriptors in the Microsoft runtime |
2845 | libraries, which by default is C<64> (there must be a hidden I<64> fetish |
3413 | libraries, which by default is C<64> (there must be a hidden I<64> fetish |
2846 | or something like this inside microsoft). You can increase this by calling |
3414 | or something like this inside Microsoft). You can increase this by calling |
2847 | C<_setmaxstdio>, which can increase this limit to C<2048> (another |
3415 | C<_setmaxstdio>, which can increase this limit to C<2048> (another |
2848 | arbitrary limit), but is broken in many versions of the microsoft runtime |
3416 | arbitrary limit), but is broken in many versions of the Microsoft runtime |
2849 | libraries. |
3417 | libraries. |
2850 | |
3418 | |
2851 | This might get you to about C<512> or C<2048> sockets (depending on |
3419 | This might get you to about C<512> or C<2048> sockets (depending on |
2852 | windows version and/or the phase of the moon). To get more, you need to |
3420 | windows version and/or the phase of the moon). To get more, you need to |
2853 | wrap all I/O functions and provide your own fd management, but the cost of |
3421 | wrap all I/O functions and provide your own fd management, but the cost of |
2854 | calling select (O(n²)) will likely make this unworkable. |
3422 | calling select (O(n²)) will likely make this unworkable. |
2855 | |
3423 | |
2856 | =back |
3424 | =back |
2857 | |
3425 | |
2858 | |
3426 | |
|
|
3427 | =head1 PORTABILITY REQUIREMENTS |
|
|
3428 | |
|
|
3429 | In addition to a working ISO-C implementation, libev relies on a few |
|
|
3430 | additional extensions: |
|
|
3431 | |
|
|
3432 | =over 4 |
|
|
3433 | |
|
|
3434 | =item C<void (*)(ev_watcher_type *, int revents)> must have compatible |
|
|
3435 | calling conventions regardless of C<ev_watcher_type *>. |
|
|
3436 | |
|
|
3437 | Libev assumes not only that all watcher pointers have the same internal |
|
|
3438 | structure (guaranteed by POSIX but not by ISO C for example), but it also |
|
|
3439 | assumes that the same (machine) code can be used to call any watcher |
|
|
3440 | callback: The watcher callbacks have different type signatures, but libev |
|
|
3441 | calls them using an C<ev_watcher *> internally. |
|
|
3442 | |
|
|
3443 | =item C<sig_atomic_t volatile> must be thread-atomic as well |
|
|
3444 | |
|
|
3445 | The type C<sig_atomic_t volatile> (or whatever is defined as |
|
|
3446 | C<EV_ATOMIC_T>) must be atomic w.r.t. accesses from different |
|
|
3447 | threads. This is not part of the specification for C<sig_atomic_t>, but is |
|
|
3448 | believed to be sufficiently portable. |
|
|
3449 | |
|
|
3450 | =item C<sigprocmask> must work in a threaded environment |
|
|
3451 | |
|
|
3452 | Libev uses C<sigprocmask> to temporarily block signals. This is not |
|
|
3453 | allowed in a threaded program (C<pthread_sigmask> has to be used). Typical |
|
|
3454 | pthread implementations will either allow C<sigprocmask> in the "main |
|
|
3455 | thread" or will block signals process-wide, both behaviours would |
|
|
3456 | be compatible with libev. Interaction between C<sigprocmask> and |
|
|
3457 | C<pthread_sigmask> could complicate things, however. |
|
|
3458 | |
|
|
3459 | The most portable way to handle signals is to block signals in all threads |
|
|
3460 | except the initial one, and run the default loop in the initial thread as |
|
|
3461 | well. |
|
|
3462 | |
|
|
3463 | =item C<long> must be large enough for common memory allocation sizes |
|
|
3464 | |
|
|
3465 | To improve portability and simplify using libev, libev uses C<long> |
|
|
3466 | internally instead of C<size_t> when allocating its data structures. On |
|
|
3467 | non-POSIX systems (Microsoft...) this might be unexpectedly low, but |
|
|
3468 | is still at least 31 bits everywhere, which is enough for hundreds of |
|
|
3469 | millions of watchers. |
|
|
3470 | |
|
|
3471 | =item C<double> must hold a time value in seconds with enough accuracy |
|
|
3472 | |
|
|
3473 | The type C<double> is used to represent timestamps. It is required to |
|
|
3474 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
|
|
3475 | enough for at least into the year 4000. This requirement is fulfilled by |
|
|
3476 | implementations implementing IEEE 754 (basically all existing ones). |
|
|
3477 | |
|
|
3478 | =back |
|
|
3479 | |
|
|
3480 | If you know of other additional requirements drop me a note. |
|
|
3481 | |
|
|
3482 | |
|
|
3483 | =head1 COMPILER WARNINGS |
|
|
3484 | |
|
|
3485 | Depending on your compiler and compiler settings, you might get no or a |
|
|
3486 | lot of warnings when compiling libev code. Some people are apparently |
|
|
3487 | scared by this. |
|
|
3488 | |
|
|
3489 | However, these are unavoidable for many reasons. For one, each compiler |
|
|
3490 | has different warnings, and each user has different tastes regarding |
|
|
3491 | warning options. "Warn-free" code therefore cannot be a goal except when |
|
|
3492 | targeting a specific compiler and compiler-version. |
|
|
3493 | |
|
|
3494 | Another reason is that some compiler warnings require elaborate |
|
|
3495 | workarounds, or other changes to the code that make it less clear and less |
|
|
3496 | maintainable. |
|
|
3497 | |
|
|
3498 | And of course, some compiler warnings are just plain stupid, or simply |
|
|
3499 | wrong (because they don't actually warn about the condition their message |
|
|
3500 | seems to warn about). |
|
|
3501 | |
|
|
3502 | While libev is written to generate as few warnings as possible, |
|
|
3503 | "warn-free" code is not a goal, and it is recommended not to build libev |
|
|
3504 | with any compiler warnings enabled unless you are prepared to cope with |
|
|
3505 | them (e.g. by ignoring them). Remember that warnings are just that: |
|
|
3506 | warnings, not errors, or proof of bugs. |
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3507 | |
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3508 | |
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3509 | =head1 VALGRIND |
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3510 | |
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3511 | Valgrind has a special section here because it is a popular tool that is |
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3512 | highly useful, but valgrind reports are very hard to interpret. |
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3513 | |
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3514 | If you think you found a bug (memory leak, uninitialised data access etc.) |
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3515 | in libev, then check twice: If valgrind reports something like: |
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3516 | |
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3517 | ==2274== definitely lost: 0 bytes in 0 blocks. |
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3518 | ==2274== possibly lost: 0 bytes in 0 blocks. |
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3519 | ==2274== still reachable: 256 bytes in 1 blocks. |
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3520 | |
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3521 | Then there is no memory leak. Similarly, under some circumstances, |
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3522 | valgrind might report kernel bugs as if it were a bug in libev, or it |
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3523 | might be confused (it is a very good tool, but only a tool). |
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3524 | |
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3525 | If you are unsure about something, feel free to contact the mailing list |
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3526 | with the full valgrind report and an explanation on why you think this is |
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3527 | a bug in libev. However, don't be annoyed when you get a brisk "this is |
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3528 | no bug" answer and take the chance of learning how to interpret valgrind |
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3529 | properly. |
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3530 | |
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3531 | If you need, for some reason, empty reports from valgrind for your project |
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3532 | I suggest using suppression lists. |
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3533 | |
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3534 | |
2859 | =head1 AUTHOR |
3535 | =head1 AUTHOR |
2860 | |
3536 | |
2861 | Marc Lehmann <libev@schmorp.de>. |
3537 | Marc Lehmann <libev@schmorp.de>. |
2862 | |
3538 | |