… | |
… | |
4 | |
4 | |
5 | =head1 SYNOPSIS |
5 | =head1 SYNOPSIS |
6 | |
6 | |
7 | #include <ev.h> |
7 | #include <ev.h> |
8 | |
8 | |
9 | =head1 EXAMPLE PROGRAM |
9 | =head2 EXAMPLE PROGRAM |
10 | |
10 | |
|
|
11 | // a single header file is required |
11 | #include <ev.h> |
12 | #include <ev.h> |
12 | |
13 | |
|
|
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 | |
|
|
19 | // all watcher callbacks have a similar signature |
16 | /* called when data readable on stdin */ |
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 | { |
|
|
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 |
|
|
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 | |
|
|
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 | |
|
|
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 occuring), 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 | |
61 | To do this, it must take more or less complete control over your process |
75 | To do this, it must take more or less complete control over your process |
62 | (or thread) by executing the I<event loop> handler, and will then |
76 | (or thread) by executing the I<event loop> handler, and will then |
63 | communicate events via a callback mechanism. |
77 | communicate events via a callback mechanism. |
… | |
… | |
65 | You register interest in certain events by registering so-called I<event |
79 | You register interest in certain events by registering so-called I<event |
66 | watchers>, which are relatively small C structures you initialise with the |
80 | watchers>, which are relatively small C structures you initialise with the |
67 | details of the event, and then hand it over to libev by I<starting> the |
81 | details of the event, and then hand it over to libev by I<starting> the |
68 | watcher. |
82 | watcher. |
69 | |
83 | |
70 | =head1 FEATURES |
84 | =head2 FEATURES |
71 | |
85 | |
72 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
86 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
73 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
87 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
74 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
88 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
75 | (for C<ev_stat>), relative timers (C<ev_timer>), absolute timers |
89 | (for C<ev_stat>), relative timers (C<ev_timer>), absolute timers |
… | |
… | |
82 | |
96 | |
83 | It also is quite fast (see this |
97 | It also is quite fast (see this |
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 | =head1 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 | =head1 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 such. |
118 | it, you should treat it as some floatingpoint value. Unlike the name |
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119 | component C<stamp> might indicate, it is also used for time differences |
|
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120 | throughout libev. |
104 | |
121 | |
105 | =head1 GLOBAL FUNCTIONS |
122 | =head1 GLOBAL FUNCTIONS |
106 | |
123 | |
107 | These functions can be called anytime, even before initialising the |
124 | These functions can be called anytime, even before initialising the |
108 | library in any way. |
125 | library in any way. |
… | |
… | |
113 | |
130 | |
114 | Returns the current time as libev would use it. Please note that the |
131 | Returns the current time as libev would use it. Please note that the |
115 | C<ev_now> function is usually faster and also often returns the timestamp |
132 | C<ev_now> function is usually faster and also often returns the timestamp |
116 | you actually want to know. |
133 | you actually want to know. |
117 | |
134 | |
|
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135 | =item ev_sleep (ev_tstamp interval) |
|
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136 | |
|
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137 | Sleep for the given interval: The current thread will be blocked until |
|
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138 | either it is interrupted or the given time interval has passed. Basically |
|
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139 | this is a subsecond-resolution C<sleep ()>. |
|
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140 | |
118 | =item int ev_version_major () |
141 | =item int ev_version_major () |
119 | |
142 | |
120 | =item int ev_version_minor () |
143 | =item int ev_version_minor () |
121 | |
144 | |
122 | You can find out the major and minor version numbers of the library |
145 | You can find out the major and minor ABI version numbers of the library |
123 | you linked against by calling the functions C<ev_version_major> and |
146 | you linked against by calling the functions C<ev_version_major> and |
124 | C<ev_version_minor>. If you want, you can compare against the global |
147 | C<ev_version_minor>. If you want, you can compare against the global |
125 | symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the |
148 | symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the |
126 | version of the library your program was compiled against. |
149 | version of the library your program was compiled against. |
127 | |
150 | |
|
|
151 | These version numbers refer to the ABI version of the library, not the |
|
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152 | release version. |
|
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153 | |
128 | Usually, it's a good idea to terminate if the major versions mismatch, |
154 | Usually, it's a good idea to terminate if the major versions mismatch, |
129 | as this indicates an incompatible change. Minor versions are usually |
155 | as this indicates an incompatible change. Minor versions are usually |
130 | compatible to older versions, so a larger minor version alone is usually |
156 | compatible to older versions, so a larger minor version alone is usually |
131 | not a problem. |
157 | not a problem. |
132 | |
158 | |
133 | Example: Make sure we haven't accidentally been linked against the wrong |
159 | Example: Make sure we haven't accidentally been linked against the wrong |
134 | version. |
160 | version. |
… | |
… | |
170 | See the description of C<ev_embed> watchers for more info. |
196 | See the description of C<ev_embed> watchers for more info. |
171 | |
197 | |
172 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
198 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
173 | |
199 | |
174 | Sets the allocation function to use (the prototype is similar - the |
200 | Sets the allocation function to use (the prototype is similar - the |
175 | semantics is identical - to the realloc C function). It is used to |
201 | semantics are identical to the C<realloc> C89/SuS/POSIX function). It is |
176 | allocate and free memory (no surprises here). If it returns zero when |
202 | used to allocate and free memory (no surprises here). If it returns zero |
177 | memory needs to be allocated, the library might abort or take some |
203 | when memory needs to be allocated (C<size != 0>), the library might abort |
178 | potentially destructive action. The default is your system realloc |
204 | or take some potentially destructive action. |
179 | function. |
205 | |
|
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206 | Since some systems (at least OpenBSD and Darwin) fail to implement |
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207 | correct C<realloc> semantics, libev will use a wrapper around the system |
|
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208 | C<realloc> and C<free> functions by default. |
180 | |
209 | |
181 | You could override this function in high-availability programs to, say, |
210 | You could override this function in high-availability programs to, say, |
182 | free some memory if it cannot allocate memory, to use a special allocator, |
211 | free some memory if it cannot allocate memory, to use a special allocator, |
183 | or even to sleep a while and retry until some memory is available. |
212 | or even to sleep a while and retry until some memory is available. |
184 | |
213 | |
185 | Example: Replace the libev allocator with one that waits a bit and then |
214 | Example: Replace the libev allocator with one that waits a bit and then |
186 | retries). |
215 | retries (example requires a standards-compliant C<realloc>). |
187 | |
216 | |
188 | static void * |
217 | static void * |
189 | persistent_realloc (void *ptr, size_t size) |
218 | persistent_realloc (void *ptr, size_t size) |
190 | { |
219 | { |
191 | for (;;) |
220 | for (;;) |
… | |
… | |
230 | |
259 | |
231 | An event loop is described by a C<struct ev_loop *>. The library knows two |
260 | An event loop is described by a C<struct ev_loop *>. The library knows two |
232 | types of such loops, the I<default> loop, which supports signals and child |
261 | types of such loops, the I<default> loop, which supports signals and child |
233 | events, and dynamically created loops which do not. |
262 | events, and dynamically created loops which do not. |
234 | |
263 | |
235 | If you use threads, a common model is to run the default event loop |
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236 | in your main thread (or in a separate thread) and for each thread you |
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237 | create, you also create another event loop. Libev itself does no locking |
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238 | whatsoever, so if you mix calls to the same event loop in different |
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239 | threads, make sure you lock (this is usually a bad idea, though, even if |
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240 | done correctly, because it's hideous and inefficient). |
|
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241 | |
|
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242 | =over 4 |
264 | =over 4 |
243 | |
265 | |
244 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
266 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
245 | |
267 | |
246 | This will initialise the default event loop if it hasn't been initialised |
268 | This will initialise the default event loop if it hasn't been initialised |
… | |
… | |
248 | false. If it already was initialised it simply returns it (and ignores the |
270 | false. If it already was initialised it simply returns it (and ignores the |
249 | flags. If that is troubling you, check C<ev_backend ()> afterwards). |
271 | flags. If that is troubling you, check C<ev_backend ()> afterwards). |
250 | |
272 | |
251 | If you don't know what event loop to use, use the one returned from this |
273 | If you don't know what event loop to use, use the one returned from this |
252 | function. |
274 | function. |
|
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275 | |
|
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276 | Note that this function is I<not> thread-safe, so if you want to use it |
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277 | from multiple threads, you have to lock (note also that this is unlikely, |
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278 | as loops cannot bes hared easily between threads anyway). |
|
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279 | |
|
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280 | The default loop is the only loop that can handle C<ev_signal> and |
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281 | C<ev_child> watchers, and to do this, it always registers a handler |
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282 | for C<SIGCHLD>. If this is a problem for your app you can either |
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283 | create a dynamic loop with C<ev_loop_new> that doesn't do that, or you |
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284 | can simply overwrite the C<SIGCHLD> signal handler I<after> calling |
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285 | C<ev_default_init>. |
253 | |
286 | |
254 | The flags argument can be used to specify special behaviour or specific |
287 | The flags argument can be used to specify special behaviour or specific |
255 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
288 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
256 | |
289 | |
257 | The following flags are supported: |
290 | The following flags are supported: |
… | |
… | |
279 | enabling this flag. |
312 | enabling this flag. |
280 | |
313 | |
281 | This works by calling C<getpid ()> on every iteration of the loop, |
314 | This works by calling C<getpid ()> on every iteration of the loop, |
282 | and thus this might slow down your event loop if you do a lot of loop |
315 | and thus this might slow down your event loop if you do a lot of loop |
283 | iterations and little real work, but is usually not noticeable (on my |
316 | iterations and little real work, but is usually not noticeable (on my |
284 | Linux system for example, C<getpid> is actually a simple 5-insn sequence |
317 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence |
285 | without a syscall and thus I<very> fast, but my Linux system also has |
318 | without a syscall and thus I<very> fast, but my GNU/Linux system also has |
286 | C<pthread_atfork> which is even faster). |
319 | C<pthread_atfork> which is even faster). |
287 | |
320 | |
288 | The big advantage of this flag is that you can forget about fork (and |
321 | The big advantage of this flag is that you can forget about fork (and |
289 | forget about forgetting to tell libev about forking) when you use this |
322 | forget about forgetting to tell libev about forking) when you use this |
290 | flag. |
323 | flag. |
… | |
… | |
295 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
328 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
296 | |
329 | |
297 | This is your standard select(2) backend. Not I<completely> standard, as |
330 | This is your standard select(2) backend. Not I<completely> standard, as |
298 | libev tries to roll its own fd_set with no limits on the number of fds, |
331 | libev tries to roll its own fd_set with no limits on the number of fds, |
299 | but if that fails, expect a fairly low limit on the number of fds when |
332 | but if that fails, expect a fairly low limit on the number of fds when |
300 | using this backend. It doesn't scale too well (O(highest_fd)), but its usually |
333 | using this backend. It doesn't scale too well (O(highest_fd)), but its |
301 | the fastest backend for a low number of fds. |
334 | usually the fastest backend for a low number of (low-numbered :) fds. |
|
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335 | |
|
|
336 | To get good performance out of this backend you need a high amount of |
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337 | parallelity (most of the file descriptors should be busy). If you are |
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338 | writing a server, you should C<accept ()> in a loop to accept as many |
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339 | connections as possible during one iteration. You might also want to have |
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340 | a look at C<ev_set_io_collect_interval ()> to increase the amount of |
|
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341 | readyness notifications you get per iteration. |
302 | |
342 | |
303 | =item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows) |
343 | =item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows) |
304 | |
344 | |
305 | And this is your standard poll(2) backend. It's more complicated than |
345 | And this is your standard poll(2) backend. It's more complicated |
306 | select, but handles sparse fds better and has no artificial limit on the |
346 | than select, but handles sparse fds better and has no artificial |
307 | number of fds you can use (except it will slow down considerably with a |
347 | limit on the number of fds you can use (except it will slow down |
308 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds). |
348 | considerably with a lot of inactive fds). It scales similarly to select, |
|
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349 | i.e. O(total_fds). See the entry for C<EVBACKEND_SELECT>, above, for |
|
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350 | performance tips. |
309 | |
351 | |
310 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
352 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
311 | |
353 | |
312 | For few fds, this backend is a bit little slower than poll and select, |
354 | For few fds, this backend is a bit little slower than poll and select, |
313 | but it scales phenomenally better. While poll and select usually scale like |
355 | but it scales phenomenally better. While poll and select usually scale |
314 | O(total_fds) where n is the total number of fds (or the highest fd), epoll scales |
356 | like O(total_fds) where n is the total number of fds (or the highest fd), |
315 | either O(1) or O(active_fds). |
357 | epoll scales either O(1) or O(active_fds). The epoll design has a number |
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358 | of shortcomings, such as silently dropping events in some hard-to-detect |
|
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359 | cases and requiring a syscall per fd change, no fork support and bad |
|
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360 | support for dup. |
316 | |
361 | |
317 | While stopping and starting an I/O watcher in the same iteration will |
362 | While stopping, setting and starting an I/O watcher in the same iteration |
318 | result in some caching, there is still a syscall per such incident |
363 | will result in some caching, there is still a syscall per such incident |
319 | (because the fd could point to a different file description now), so its |
364 | (because the fd could point to a different file description now), so its |
320 | best to avoid that. Also, dup()ed file descriptors might not work very |
365 | best to avoid that. Also, C<dup ()>'ed file descriptors might not work |
321 | well if you register events for both fds. |
366 | very well if you register events for both fds. |
322 | |
367 | |
323 | Please note that epoll sometimes generates spurious notifications, so you |
368 | Please note that epoll sometimes generates spurious notifications, so you |
324 | need to use non-blocking I/O or other means to avoid blocking when no data |
369 | need to use non-blocking I/O or other means to avoid blocking when no data |
325 | (or space) is available. |
370 | (or space) is available. |
326 | |
371 | |
|
|
372 | Best performance from this backend is achieved by not unregistering all |
|
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373 | watchers for a file descriptor until it has been closed, if possible, i.e. |
|
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374 | keep at least one watcher active per fd at all times. |
|
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375 | |
|
|
376 | While nominally embeddeble in other event loops, this feature is broken in |
|
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377 | all kernel versions tested so far. |
|
|
378 | |
327 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
379 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
328 | |
380 | |
329 | Kqueue deserves special mention, as at the time of this writing, it |
381 | Kqueue deserves special mention, as at the time of this writing, it |
330 | was broken on all BSDs except NetBSD (usually it doesn't work with |
382 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
331 | anything but sockets and pipes, except on Darwin, where of course its |
383 | with anything but sockets and pipes, except on Darwin, where of course |
332 | completely useless). For this reason its not being "autodetected" |
384 | it's completely useless). For this reason it's not being "autodetected" |
333 | unless you explicitly specify it explicitly in the flags (i.e. using |
385 | unless you explicitly specify it explicitly in the flags (i.e. using |
334 | C<EVBACKEND_KQUEUE>). |
386 | C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough) |
|
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387 | system like NetBSD. |
|
|
388 | |
|
|
389 | You still can embed kqueue into a normal poll or select backend and use it |
|
|
390 | only for sockets (after having made sure that sockets work with kqueue on |
|
|
391 | the target platform). See C<ev_embed> watchers for more info. |
335 | |
392 | |
336 | It scales in the same way as the epoll backend, but the interface to the |
393 | It scales in the same way as the epoll backend, but the interface to the |
337 | kernel is more efficient (which says nothing about its actual speed, of |
394 | kernel is more efficient (which says nothing about its actual speed, of |
338 | course). While starting and stopping an I/O watcher does not cause an |
395 | course). While stopping, setting and starting an I/O watcher does never |
339 | extra syscall as with epoll, it still adds up to four event changes per |
396 | cause an extra syscall as with C<EVBACKEND_EPOLL>, it still adds up to |
340 | incident, so its best to avoid that. |
397 | two event changes per incident, support for C<fork ()> is very bad and it |
|
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398 | drops fds silently in similarly hard-to-detect cases. |
|
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399 | |
|
|
400 | This backend usually performs well under most conditions. |
|
|
401 | |
|
|
402 | While nominally embeddable in other event loops, this doesn't work |
|
|
403 | everywhere, so you might need to test for this. And since it is broken |
|
|
404 | almost everywhere, you should only use it when you have a lot of sockets |
|
|
405 | (for which it usually works), by embedding it into another event loop |
|
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406 | (e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>) and using it only for |
|
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407 | sockets. |
341 | |
408 | |
342 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
409 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
343 | |
410 | |
344 | This is not implemented yet (and might never be). |
411 | This is not implemented yet (and might never be, unless you send me an |
|
|
412 | implementation). According to reports, C</dev/poll> only supports sockets |
|
|
413 | and is not embeddable, which would limit the usefulness of this backend |
|
|
414 | immensely. |
345 | |
415 | |
346 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
416 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
347 | |
417 | |
348 | This uses the Solaris 10 port mechanism. As with everything on Solaris, |
418 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
349 | it's really slow, but it still scales very well (O(active_fds)). |
419 | it's really slow, but it still scales very well (O(active_fds)). |
350 | |
420 | |
351 | Please note that solaris ports can result in a lot of spurious |
421 | Please note that solaris event ports can deliver a lot of spurious |
352 | notifications, so you need to use non-blocking I/O or other means to avoid |
422 | notifications, so you need to use non-blocking I/O or other means to avoid |
353 | blocking when no data (or space) is available. |
423 | blocking when no data (or space) is available. |
|
|
424 | |
|
|
425 | While this backend scales well, it requires one system call per active |
|
|
426 | file descriptor per loop iteration. For small and medium numbers of file |
|
|
427 | descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend |
|
|
428 | might perform better. |
|
|
429 | |
|
|
430 | On the positive side, ignoring the spurious readyness notifications, this |
|
|
431 | backend actually performed to specification in all tests and is fully |
|
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432 | embeddable, which is a rare feat among the OS-specific backends. |
354 | |
433 | |
355 | =item C<EVBACKEND_ALL> |
434 | =item C<EVBACKEND_ALL> |
356 | |
435 | |
357 | Try all backends (even potentially broken ones that wouldn't be tried |
436 | Try all backends (even potentially broken ones that wouldn't be tried |
358 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
437 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
359 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
438 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
360 | |
439 | |
|
|
440 | It is definitely not recommended to use this flag. |
|
|
441 | |
361 | =back |
442 | =back |
362 | |
443 | |
363 | If one or more of these are ored into the flags value, then only these |
444 | If one or more of these are ored into the flags value, then only these |
364 | backends will be tried (in the reverse order as given here). If none are |
445 | backends will be tried (in the reverse order as listed here). If none are |
365 | specified, most compiled-in backend will be tried, usually in reverse |
446 | specified, all backends in C<ev_recommended_backends ()> will be tried. |
366 | order of their flag values :) |
|
|
367 | |
447 | |
368 | The most typical usage is like this: |
448 | The most typical usage is like this: |
369 | |
449 | |
370 | if (!ev_default_loop (0)) |
450 | if (!ev_default_loop (0)) |
371 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
451 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
… | |
… | |
385 | |
465 | |
386 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
466 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
387 | always distinct from the default loop. Unlike the default loop, it cannot |
467 | always distinct from the default loop. Unlike the default loop, it cannot |
388 | handle signal and child watchers, and attempts to do so will be greeted by |
468 | handle signal and child watchers, and attempts to do so will be greeted by |
389 | undefined behaviour (or a failed assertion if assertions are enabled). |
469 | undefined behaviour (or a failed assertion if assertions are enabled). |
|
|
470 | |
|
|
471 | Note that this function I<is> thread-safe, and the recommended way to use |
|
|
472 | libev with threads is indeed to create one loop per thread, and using the |
|
|
473 | default loop in the "main" or "initial" thread. |
390 | |
474 | |
391 | Example: Try to create a event loop that uses epoll and nothing else. |
475 | Example: Try to create a event loop that uses epoll and nothing else. |
392 | |
476 | |
393 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
477 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
394 | if (!epoller) |
478 | if (!epoller) |
… | |
… | |
399 | Destroys the default loop again (frees all memory and kernel state |
483 | Destroys the default loop again (frees all memory and kernel state |
400 | etc.). None of the active event watchers will be stopped in the normal |
484 | etc.). None of the active event watchers will be stopped in the normal |
401 | sense, so e.g. C<ev_is_active> might still return true. It is your |
485 | sense, so e.g. C<ev_is_active> might still return true. It is your |
402 | responsibility to either stop all watchers cleanly yoursef I<before> |
486 | responsibility to either stop all watchers cleanly yoursef I<before> |
403 | calling this function, or cope with the fact afterwards (which is usually |
487 | calling this function, or cope with the fact afterwards (which is usually |
404 | the easiest thing, youc na just ignore the watchers and/or C<free ()> them |
488 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
405 | for example). |
489 | for example). |
|
|
490 | |
|
|
491 | Note that certain global state, such as signal state, will not be freed by |
|
|
492 | this function, and related watchers (such as signal and child watchers) |
|
|
493 | would need to be stopped manually. |
|
|
494 | |
|
|
495 | In general it is not advisable to call this function except in the |
|
|
496 | rare occasion where you really need to free e.g. the signal handling |
|
|
497 | pipe fds. If you need dynamically allocated loops it is better to use |
|
|
498 | C<ev_loop_new> and C<ev_loop_destroy>). |
406 | |
499 | |
407 | =item ev_loop_destroy (loop) |
500 | =item ev_loop_destroy (loop) |
408 | |
501 | |
409 | Like C<ev_default_destroy>, but destroys an event loop created by an |
502 | Like C<ev_default_destroy>, but destroys an event loop created by an |
410 | earlier call to C<ev_loop_new>. |
503 | earlier call to C<ev_loop_new>. |
411 | |
504 | |
412 | =item ev_default_fork () |
505 | =item ev_default_fork () |
413 | |
506 | |
|
|
507 | This function sets a flag that causes subsequent C<ev_loop> iterations |
414 | This function reinitialises the kernel state for backends that have |
508 | to reinitialise the kernel state for backends that have one. Despite the |
415 | one. Despite the name, you can call it anytime, but it makes most sense |
509 | name, you can call it anytime, but it makes most sense after forking, in |
416 | after forking, in either the parent or child process (or both, but that |
510 | the child process (or both child and parent, but that again makes little |
417 | again makes little sense). |
511 | sense). You I<must> call it in the child before using any of the libev |
|
|
512 | functions, and it will only take effect at the next C<ev_loop> iteration. |
418 | |
513 | |
419 | You I<must> call this function in the child process after forking if and |
514 | On the other hand, you only need to call this function in the child |
420 | only if you want to use the event library in both processes. If you just |
515 | process if and only if you want to use the event library in the child. If |
421 | fork+exec, you don't have to call it. |
516 | you just fork+exec, you don't have to call it at all. |
422 | |
517 | |
423 | The function itself is quite fast and it's usually not a problem to call |
518 | The function itself is quite fast and it's usually not a problem to call |
424 | it just in case after a fork. To make this easy, the function will fit in |
519 | it just in case after a fork. To make this easy, the function will fit in |
425 | quite nicely into a call to C<pthread_atfork>: |
520 | quite nicely into a call to C<pthread_atfork>: |
426 | |
521 | |
427 | pthread_atfork (0, 0, ev_default_fork); |
522 | pthread_atfork (0, 0, ev_default_fork); |
428 | |
523 | |
429 | At the moment, C<EVBACKEND_SELECT> and C<EVBACKEND_POLL> are safe to use |
|
|
430 | without calling this function, so if you force one of those backends you |
|
|
431 | do not need to care. |
|
|
432 | |
|
|
433 | =item ev_loop_fork (loop) |
524 | =item ev_loop_fork (loop) |
434 | |
525 | |
435 | Like C<ev_default_fork>, but acts on an event loop created by |
526 | Like C<ev_default_fork>, but acts on an event loop created by |
436 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
527 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
437 | after fork, and how you do this is entirely your own problem. |
528 | after fork, and how you do this is entirely your own problem. |
|
|
529 | |
|
|
530 | =item int ev_is_default_loop (loop) |
|
|
531 | |
|
|
532 | Returns true when the given loop actually is the default loop, false otherwise. |
438 | |
533 | |
439 | =item unsigned int ev_loop_count (loop) |
534 | =item unsigned int ev_loop_count (loop) |
440 | |
535 | |
441 | Returns the count of loop iterations for the loop, which is identical to |
536 | Returns the count of loop iterations for the loop, which is identical to |
442 | the number of times libev did poll for new events. It starts at C<0> and |
537 | the number of times libev did poll for new events. It starts at C<0> and |
… | |
… | |
455 | |
550 | |
456 | Returns the current "event loop time", which is the time the event loop |
551 | Returns the current "event loop time", which is the time the event loop |
457 | received events and started processing them. This timestamp does not |
552 | received events and started processing them. This timestamp does not |
458 | change as long as callbacks are being processed, and this is also the base |
553 | change as long as callbacks are being processed, and this is also the base |
459 | time used for relative timers. You can treat it as the timestamp of the |
554 | time used for relative timers. You can treat it as the timestamp of the |
460 | event occuring (or more correctly, libev finding out about it). |
555 | event occurring (or more correctly, libev finding out about it). |
461 | |
556 | |
462 | =item ev_loop (loop, int flags) |
557 | =item ev_loop (loop, int flags) |
463 | |
558 | |
464 | Finally, this is it, the event handler. This function usually is called |
559 | Finally, this is it, the event handler. This function usually is called |
465 | after you initialised all your watchers and you want to start handling |
560 | after you initialised all your watchers and you want to start handling |
… | |
… | |
486 | libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is |
581 | libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is |
487 | usually a better approach for this kind of thing. |
582 | usually a better approach for this kind of thing. |
488 | |
583 | |
489 | Here are the gory details of what C<ev_loop> does: |
584 | Here are the gory details of what C<ev_loop> does: |
490 | |
585 | |
491 | * If there are no active watchers (reference count is zero), return. |
586 | - Before the first iteration, call any pending watchers. |
492 | - Queue prepare watchers and then call all outstanding watchers. |
587 | * If EVFLAG_FORKCHECK was used, check for a fork. |
|
|
588 | - If a fork was detected, queue and call all fork watchers. |
|
|
589 | - Queue and call all prepare watchers. |
493 | - If we have been forked, recreate the kernel state. |
590 | - If we have been forked, recreate the kernel state. |
494 | - Update the kernel state with all outstanding changes. |
591 | - Update the kernel state with all outstanding changes. |
495 | - Update the "event loop time". |
592 | - Update the "event loop time". |
496 | - Calculate for how long to block. |
593 | - Calculate for how long to sleep or block, if at all |
|
|
594 | (active idle watchers, EVLOOP_NONBLOCK or not having |
|
|
595 | any active watchers at all will result in not sleeping). |
|
|
596 | - Sleep if the I/O and timer collect interval say so. |
497 | - Block the process, waiting for any events. |
597 | - Block the process, waiting for any events. |
498 | - Queue all outstanding I/O (fd) events. |
598 | - Queue all outstanding I/O (fd) events. |
499 | - Update the "event loop time" and do time jump handling. |
599 | - Update the "event loop time" and do time jump handling. |
500 | - Queue all outstanding timers. |
600 | - Queue all outstanding timers. |
501 | - Queue all outstanding periodics. |
601 | - Queue all outstanding periodics. |
502 | - If no events are pending now, queue all idle watchers. |
602 | - If no events are pending now, queue all idle watchers. |
503 | - Queue all check watchers. |
603 | - Queue all check watchers. |
504 | - Call all queued watchers in reverse order (i.e. check watchers first). |
604 | - Call all queued watchers in reverse order (i.e. check watchers first). |
505 | Signals and child watchers are implemented as I/O watchers, and will |
605 | Signals and child watchers are implemented as I/O watchers, and will |
506 | be handled here by queueing them when their watcher gets executed. |
606 | be handled here by queueing them when their watcher gets executed. |
507 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
607 | - If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
508 | were used, return, otherwise continue with step *. |
608 | were used, or there are no active watchers, return, otherwise |
|
|
609 | continue with step *. |
509 | |
610 | |
510 | Example: Queue some jobs and then loop until no events are outsanding |
611 | Example: Queue some jobs and then loop until no events are outstanding |
511 | anymore. |
612 | anymore. |
512 | |
613 | |
513 | ... queue jobs here, make sure they register event watchers as long |
614 | ... queue jobs here, make sure they register event watchers as long |
514 | ... as they still have work to do (even an idle watcher will do..) |
615 | ... as they still have work to do (even an idle watcher will do..) |
515 | ev_loop (my_loop, 0); |
616 | ev_loop (my_loop, 0); |
… | |
… | |
519 | |
620 | |
520 | Can be used to make a call to C<ev_loop> return early (but only after it |
621 | Can be used to make a call to C<ev_loop> return early (but only after it |
521 | has processed all outstanding events). The C<how> argument must be either |
622 | has processed all outstanding events). The C<how> argument must be either |
522 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
623 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
523 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
624 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
|
|
625 | |
|
|
626 | This "unloop state" will be cleared when entering C<ev_loop> again. |
524 | |
627 | |
525 | =item ev_ref (loop) |
628 | =item ev_ref (loop) |
526 | |
629 | |
527 | =item ev_unref (loop) |
630 | =item ev_unref (loop) |
528 | |
631 | |
… | |
… | |
533 | returning, ev_unref() after starting, and ev_ref() before stopping it. For |
636 | returning, ev_unref() after starting, and ev_ref() before stopping it. For |
534 | example, libev itself uses this for its internal signal pipe: It is not |
637 | example, libev itself uses this for its internal signal pipe: It is not |
535 | visible to the libev user and should not keep C<ev_loop> from exiting if |
638 | visible to the libev user and should not keep C<ev_loop> from exiting if |
536 | no event watchers registered by it are active. It is also an excellent |
639 | no event watchers registered by it are active. It is also an excellent |
537 | way to do this for generic recurring timers or from within third-party |
640 | way to do this for generic recurring timers or from within third-party |
538 | libraries. Just remember to I<unref after start> and I<ref before stop>. |
641 | libraries. Just remember to I<unref after start> and I<ref before stop> |
|
|
642 | (but only if the watcher wasn't active before, or was active before, |
|
|
643 | respectively). |
539 | |
644 | |
540 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
645 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
541 | running when nothing else is active. |
646 | running when nothing else is active. |
542 | |
647 | |
543 | struct ev_signal exitsig; |
648 | struct ev_signal exitsig; |
… | |
… | |
547 | |
652 | |
548 | Example: For some weird reason, unregister the above signal handler again. |
653 | Example: For some weird reason, unregister the above signal handler again. |
549 | |
654 | |
550 | ev_ref (loop); |
655 | ev_ref (loop); |
551 | ev_signal_stop (loop, &exitsig); |
656 | ev_signal_stop (loop, &exitsig); |
|
|
657 | |
|
|
658 | =item ev_set_io_collect_interval (loop, ev_tstamp interval) |
|
|
659 | |
|
|
660 | =item ev_set_timeout_collect_interval (loop, ev_tstamp interval) |
|
|
661 | |
|
|
662 | These advanced functions influence the time that libev will spend waiting |
|
|
663 | for events. Both are by default C<0>, meaning that libev will try to |
|
|
664 | invoke timer/periodic callbacks and I/O callbacks with minimum latency. |
|
|
665 | |
|
|
666 | Setting these to a higher value (the C<interval> I<must> be >= C<0>) |
|
|
667 | allows libev to delay invocation of I/O and timer/periodic callbacks to |
|
|
668 | increase efficiency of loop iterations. |
|
|
669 | |
|
|
670 | The background is that sometimes your program runs just fast enough to |
|
|
671 | handle one (or very few) event(s) per loop iteration. While this makes |
|
|
672 | the program responsive, it also wastes a lot of CPU time to poll for new |
|
|
673 | events, especially with backends like C<select ()> which have a high |
|
|
674 | overhead for the actual polling but can deliver many events at once. |
|
|
675 | |
|
|
676 | By setting a higher I<io collect interval> you allow libev to spend more |
|
|
677 | time collecting I/O events, so you can handle more events per iteration, |
|
|
678 | at the cost of increasing latency. Timeouts (both C<ev_periodic> and |
|
|
679 | C<ev_timer>) will be not affected. Setting this to a non-null value will |
|
|
680 | introduce an additional C<ev_sleep ()> call into most loop iterations. |
|
|
681 | |
|
|
682 | Likewise, by setting a higher I<timeout collect interval> you allow libev |
|
|
683 | to spend more time collecting timeouts, at the expense of increased |
|
|
684 | latency (the watcher callback will be called later). C<ev_io> watchers |
|
|
685 | will not be affected. Setting this to a non-null value will not introduce |
|
|
686 | any overhead in libev. |
|
|
687 | |
|
|
688 | Many (busy) programs can usually benefit by setting the io collect |
|
|
689 | interval to a value near C<0.1> or so, which is often enough for |
|
|
690 | interactive servers (of course not for games), likewise for timeouts. It |
|
|
691 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
|
|
692 | as this approsaches the timing granularity of most systems. |
552 | |
693 | |
553 | =back |
694 | =back |
554 | |
695 | |
555 | |
696 | |
556 | =head1 ANATOMY OF A WATCHER |
697 | =head1 ANATOMY OF A WATCHER |
… | |
… | |
656 | =item C<EV_FORK> |
797 | =item C<EV_FORK> |
657 | |
798 | |
658 | The event loop has been resumed in the child process after fork (see |
799 | The event loop has been resumed in the child process after fork (see |
659 | C<ev_fork>). |
800 | C<ev_fork>). |
660 | |
801 | |
|
|
802 | =item C<EV_ASYNC> |
|
|
803 | |
|
|
804 | The given async watcher has been asynchronously notified (see C<ev_async>). |
|
|
805 | |
661 | =item C<EV_ERROR> |
806 | =item C<EV_ERROR> |
662 | |
807 | |
663 | An unspecified error has occured, the watcher has been stopped. This might |
808 | An unspecified error has occured, the watcher has been stopped. This might |
664 | happen because the watcher could not be properly started because libev |
809 | happen because the watcher could not be properly started because libev |
665 | ran out of memory, a file descriptor was found to be closed or any other |
810 | ran out of memory, a file descriptor was found to be closed or any other |
… | |
… | |
776 | always C<0>, which is supposed to not be too high and not be too low :). |
921 | always C<0>, which is supposed to not be too high and not be too low :). |
777 | |
922 | |
778 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
923 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
779 | fine, as long as you do not mind that the priority value you query might |
924 | fine, as long as you do not mind that the priority value you query might |
780 | or might not have been adjusted to be within valid range. |
925 | or might not have been adjusted to be within valid range. |
|
|
926 | |
|
|
927 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
|
|
928 | |
|
|
929 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
|
|
930 | C<loop> nor C<revents> need to be valid as long as the watcher callback |
|
|
931 | can deal with that fact. |
|
|
932 | |
|
|
933 | =item int ev_clear_pending (loop, ev_TYPE *watcher) |
|
|
934 | |
|
|
935 | If the watcher is pending, this function returns clears its pending status |
|
|
936 | and returns its C<revents> bitset (as if its callback was invoked). If the |
|
|
937 | watcher isn't pending it does nothing and returns C<0>. |
781 | |
938 | |
782 | =back |
939 | =back |
783 | |
940 | |
784 | |
941 | |
785 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
942 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
… | |
… | |
870 | In general you can register as many read and/or write event watchers per |
1027 | In general you can register as many read and/or write event watchers per |
871 | fd as you want (as long as you don't confuse yourself). Setting all file |
1028 | fd as you want (as long as you don't confuse yourself). Setting all file |
872 | descriptors to non-blocking mode is also usually a good idea (but not |
1029 | descriptors to non-blocking mode is also usually a good idea (but not |
873 | required if you know what you are doing). |
1030 | required if you know what you are doing). |
874 | |
1031 | |
875 | You have to be careful with dup'ed file descriptors, though. Some backends |
|
|
876 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
|
|
877 | descriptors correctly if you register interest in two or more fds pointing |
|
|
878 | to the same underlying file/socket/etc. description (that is, they share |
|
|
879 | the same underlying "file open"). |
|
|
880 | |
|
|
881 | If you must do this, then force the use of a known-to-be-good backend |
1032 | If you must do this, then force the use of a known-to-be-good backend |
882 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
1033 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
883 | C<EVBACKEND_POLL>). |
1034 | C<EVBACKEND_POLL>). |
884 | |
1035 | |
885 | Another thing you have to watch out for is that it is quite easy to |
1036 | Another thing you have to watch out for is that it is quite easy to |
… | |
… | |
895 | play around with an Xlib connection), then you have to seperately re-test |
1046 | play around with an Xlib connection), then you have to seperately re-test |
896 | whether a file descriptor is really ready with a known-to-be good interface |
1047 | whether a file descriptor is really ready with a known-to-be good interface |
897 | such as poll (fortunately in our Xlib example, Xlib already does this on |
1048 | such as poll (fortunately in our Xlib example, Xlib already does this on |
898 | its own, so its quite safe to use). |
1049 | its own, so its quite safe to use). |
899 | |
1050 | |
|
|
1051 | =head3 The special problem of disappearing file descriptors |
|
|
1052 | |
|
|
1053 | Some backends (e.g. kqueue, epoll) need to be told about closing a file |
|
|
1054 | descriptor (either by calling C<close> explicitly or by any other means, |
|
|
1055 | such as C<dup>). The reason is that you register interest in some file |
|
|
1056 | descriptor, but when it goes away, the operating system will silently drop |
|
|
1057 | this interest. If another file descriptor with the same number then is |
|
|
1058 | registered with libev, there is no efficient way to see that this is, in |
|
|
1059 | fact, a different file descriptor. |
|
|
1060 | |
|
|
1061 | To avoid having to explicitly tell libev about such cases, libev follows |
|
|
1062 | the following policy: Each time C<ev_io_set> is being called, libev |
|
|
1063 | will assume that this is potentially a new file descriptor, otherwise |
|
|
1064 | it is assumed that the file descriptor stays the same. That means that |
|
|
1065 | you I<have> to call C<ev_io_set> (or C<ev_io_init>) when you change the |
|
|
1066 | descriptor even if the file descriptor number itself did not change. |
|
|
1067 | |
|
|
1068 | This is how one would do it normally anyway, the important point is that |
|
|
1069 | the libev application should not optimise around libev but should leave |
|
|
1070 | optimisations to libev. |
|
|
1071 | |
|
|
1072 | =head3 The special problem of dup'ed file descriptors |
|
|
1073 | |
|
|
1074 | Some backends (e.g. epoll), cannot register events for file descriptors, |
|
|
1075 | but only events for the underlying file descriptions. That means when you |
|
|
1076 | have C<dup ()>'ed file descriptors or weirder constellations, and register |
|
|
1077 | events for them, only one file descriptor might actually receive events. |
|
|
1078 | |
|
|
1079 | There is no workaround possible except not registering events |
|
|
1080 | for potentially C<dup ()>'ed file descriptors, or to resort to |
|
|
1081 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
|
|
1082 | |
|
|
1083 | =head3 The special problem of fork |
|
|
1084 | |
|
|
1085 | Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit |
|
|
1086 | useless behaviour. Libev fully supports fork, but needs to be told about |
|
|
1087 | it in the child. |
|
|
1088 | |
|
|
1089 | To support fork in your programs, you either have to call |
|
|
1090 | C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child, |
|
|
1091 | enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or |
|
|
1092 | C<EVBACKEND_POLL>. |
|
|
1093 | |
|
|
1094 | =head3 The special problem of SIGPIPE |
|
|
1095 | |
|
|
1096 | While not really specific to libev, it is easy to forget about SIGPIPE: |
|
|
1097 | when reading from a pipe whose other end has been closed, your program |
|
|
1098 | gets send a SIGPIPE, which, by default, aborts your program. For most |
|
|
1099 | programs this is sensible behaviour, for daemons, this is usually |
|
|
1100 | undesirable. |
|
|
1101 | |
|
|
1102 | So when you encounter spurious, unexplained daemon exits, make sure you |
|
|
1103 | ignore SIGPIPE (and maybe make sure you log the exit status of your daemon |
|
|
1104 | somewhere, as that would have given you a big clue). |
|
|
1105 | |
|
|
1106 | |
|
|
1107 | =head3 Watcher-Specific Functions |
|
|
1108 | |
900 | =over 4 |
1109 | =over 4 |
901 | |
1110 | |
902 | =item ev_io_init (ev_io *, callback, int fd, int events) |
1111 | =item ev_io_init (ev_io *, callback, int fd, int events) |
903 | |
1112 | |
904 | =item ev_io_set (ev_io *, int fd, int events) |
1113 | =item ev_io_set (ev_io *, int fd, int events) |
… | |
… | |
914 | =item int events [read-only] |
1123 | =item int events [read-only] |
915 | |
1124 | |
916 | The events being watched. |
1125 | The events being watched. |
917 | |
1126 | |
918 | =back |
1127 | =back |
|
|
1128 | |
|
|
1129 | =head3 Examples |
919 | |
1130 | |
920 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
1131 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
921 | readable, but only once. Since it is likely line-buffered, you could |
1132 | readable, but only once. Since it is likely line-buffered, you could |
922 | attempt to read a whole line in the callback. |
1133 | attempt to read a whole line in the callback. |
923 | |
1134 | |
… | |
… | |
957 | |
1168 | |
958 | The callback is guarenteed to be invoked only when its timeout has passed, |
1169 | The callback is guarenteed to be invoked only when its timeout has passed, |
959 | but if multiple timers become ready during the same loop iteration then |
1170 | but if multiple timers become ready during the same loop iteration then |
960 | order of execution is undefined. |
1171 | order of execution is undefined. |
961 | |
1172 | |
|
|
1173 | =head3 Watcher-Specific Functions and Data Members |
|
|
1174 | |
962 | =over 4 |
1175 | =over 4 |
963 | |
1176 | |
964 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
1177 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
965 | |
1178 | |
966 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
1179 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
… | |
… | |
974 | configure a timer to trigger every 10 seconds, then it will trigger at |
1187 | configure a timer to trigger every 10 seconds, then it will trigger at |
975 | exactly 10 second intervals. If, however, your program cannot keep up with |
1188 | exactly 10 second intervals. If, however, your program cannot keep up with |
976 | the timer (because it takes longer than those 10 seconds to do stuff) the |
1189 | the timer (because it takes longer than those 10 seconds to do stuff) the |
977 | timer will not fire more than once per event loop iteration. |
1190 | timer will not fire more than once per event loop iteration. |
978 | |
1191 | |
979 | =item ev_timer_again (loop) |
1192 | =item ev_timer_again (loop, ev_timer *) |
980 | |
1193 | |
981 | This will act as if the timer timed out and restart it again if it is |
1194 | This will act as if the timer timed out and restart it again if it is |
982 | repeating. The exact semantics are: |
1195 | repeating. The exact semantics are: |
983 | |
1196 | |
984 | If the timer is pending, its pending status is cleared. |
1197 | If the timer is pending, its pending status is cleared. |
… | |
… | |
1019 | or C<ev_timer_again> is called and determines the next timeout (if any), |
1232 | or C<ev_timer_again> is called and determines the next timeout (if any), |
1020 | which is also when any modifications are taken into account. |
1233 | which is also when any modifications are taken into account. |
1021 | |
1234 | |
1022 | =back |
1235 | =back |
1023 | |
1236 | |
|
|
1237 | =head3 Examples |
|
|
1238 | |
1024 | Example: Create a timer that fires after 60 seconds. |
1239 | Example: Create a timer that fires after 60 seconds. |
1025 | |
1240 | |
1026 | static void |
1241 | static void |
1027 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1242 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1028 | { |
1243 | { |
… | |
… | |
1061 | but on wallclock time (absolute time). You can tell a periodic watcher |
1276 | but on wallclock time (absolute time). You can tell a periodic watcher |
1062 | to trigger "at" some specific point in time. For example, if you tell a |
1277 | to trigger "at" some specific point in time. For example, if you tell a |
1063 | periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now () |
1278 | periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now () |
1064 | + 10.>) and then reset your system clock to the last year, then it will |
1279 | + 10.>) and then reset your system clock to the last year, then it will |
1065 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
1280 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
1066 | roughly 10 seconds later and of course not if you reset your system time |
1281 | roughly 10 seconds later). |
1067 | again). |
|
|
1068 | |
1282 | |
1069 | They can also be used to implement vastly more complex timers, such as |
1283 | They can also be used to implement vastly more complex timers, such as |
1070 | triggering an event on eahc midnight, local time. |
1284 | triggering an event on each midnight, local time or other, complicated, |
|
|
1285 | rules. |
1071 | |
1286 | |
1072 | As with timers, the callback is guarenteed to be invoked only when the |
1287 | As with timers, the callback is guarenteed to be invoked only when the |
1073 | time (C<at>) has been passed, but if multiple periodic timers become ready |
1288 | time (C<at>) has been passed, but if multiple periodic timers become ready |
1074 | during the same loop iteration then order of execution is undefined. |
1289 | during the same loop iteration then order of execution is undefined. |
1075 | |
1290 | |
|
|
1291 | =head3 Watcher-Specific Functions and Data Members |
|
|
1292 | |
1076 | =over 4 |
1293 | =over 4 |
1077 | |
1294 | |
1078 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
1295 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
1079 | |
1296 | |
1080 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
1297 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
… | |
… | |
1082 | Lots of arguments, lets sort it out... There are basically three modes of |
1299 | Lots of arguments, lets sort it out... There are basically three modes of |
1083 | operation, and we will explain them from simplest to complex: |
1300 | operation, and we will explain them from simplest to complex: |
1084 | |
1301 | |
1085 | =over 4 |
1302 | =over 4 |
1086 | |
1303 | |
1087 | =item * absolute timer (interval = reschedule_cb = 0) |
1304 | =item * absolute timer (at = time, interval = reschedule_cb = 0) |
1088 | |
1305 | |
1089 | In this configuration the watcher triggers an event at the wallclock time |
1306 | In this configuration the watcher triggers an event at the wallclock time |
1090 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
1307 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
1091 | that is, if it is to be run at January 1st 2011 then it will run when the |
1308 | that is, if it is to be run at January 1st 2011 then it will run when the |
1092 | system time reaches or surpasses this time. |
1309 | system time reaches or surpasses this time. |
1093 | |
1310 | |
1094 | =item * non-repeating interval timer (interval > 0, reschedule_cb = 0) |
1311 | =item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
1095 | |
1312 | |
1096 | In this mode the watcher will always be scheduled to time out at the next |
1313 | In this mode the watcher will always be scheduled to time out at the next |
1097 | C<at + N * interval> time (for some integer N) and then repeat, regardless |
1314 | C<at + N * interval> time (for some integer N, which can also be negative) |
1098 | of any time jumps. |
1315 | and then repeat, regardless of any time jumps. |
1099 | |
1316 | |
1100 | This can be used to create timers that do not drift with respect to system |
1317 | This can be used to create timers that do not drift with respect to system |
1101 | time: |
1318 | time: |
1102 | |
1319 | |
1103 | ev_periodic_set (&periodic, 0., 3600., 0); |
1320 | ev_periodic_set (&periodic, 0., 3600., 0); |
… | |
… | |
1109 | |
1326 | |
1110 | Another way to think about it (for the mathematically inclined) is that |
1327 | Another way to think about it (for the mathematically inclined) is that |
1111 | C<ev_periodic> will try to run the callback in this mode at the next possible |
1328 | C<ev_periodic> will try to run the callback in this mode at the next possible |
1112 | time where C<time = at (mod interval)>, regardless of any time jumps. |
1329 | time where C<time = at (mod interval)>, regardless of any time jumps. |
1113 | |
1330 | |
|
|
1331 | For numerical stability it is preferable that the C<at> value is near |
|
|
1332 | C<ev_now ()> (the current time), but there is no range requirement for |
|
|
1333 | this value. |
|
|
1334 | |
1114 | =item * manual reschedule mode (reschedule_cb = callback) |
1335 | =item * manual reschedule mode (at and interval ignored, reschedule_cb = callback) |
1115 | |
1336 | |
1116 | In this mode the values for C<interval> and C<at> are both being |
1337 | In this mode the values for C<interval> and C<at> are both being |
1117 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1338 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1118 | reschedule callback will be called with the watcher as first, and the |
1339 | reschedule callback will be called with the watcher as first, and the |
1119 | current time as second argument. |
1340 | current time as second argument. |
1120 | |
1341 | |
1121 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
1342 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
1122 | ever, or make any event loop modifications>. If you need to stop it, |
1343 | ever, or make any event loop modifications>. If you need to stop it, |
1123 | return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by |
1344 | return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by |
1124 | starting a prepare watcher). |
1345 | starting an C<ev_prepare> watcher, which is legal). |
1125 | |
1346 | |
1126 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1347 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1127 | ev_tstamp now)>, e.g.: |
1348 | ev_tstamp now)>, e.g.: |
1128 | |
1349 | |
1129 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
1350 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
… | |
… | |
1152 | Simply stops and restarts the periodic watcher again. This is only useful |
1373 | Simply stops and restarts the periodic watcher again. This is only useful |
1153 | when you changed some parameters or the reschedule callback would return |
1374 | when you changed some parameters or the reschedule callback would return |
1154 | a different time than the last time it was called (e.g. in a crond like |
1375 | a different time than the last time it was called (e.g. in a crond like |
1155 | program when the crontabs have changed). |
1376 | program when the crontabs have changed). |
1156 | |
1377 | |
|
|
1378 | =item ev_tstamp ev_periodic_at (ev_periodic *) |
|
|
1379 | |
|
|
1380 | When active, returns the absolute time that the watcher is supposed to |
|
|
1381 | trigger next. |
|
|
1382 | |
|
|
1383 | =item ev_tstamp offset [read-write] |
|
|
1384 | |
|
|
1385 | When repeating, this contains the offset value, otherwise this is the |
|
|
1386 | absolute point in time (the C<at> value passed to C<ev_periodic_set>). |
|
|
1387 | |
|
|
1388 | Can be modified any time, but changes only take effect when the periodic |
|
|
1389 | timer fires or C<ev_periodic_again> is being called. |
|
|
1390 | |
1157 | =item ev_tstamp interval [read-write] |
1391 | =item ev_tstamp interval [read-write] |
1158 | |
1392 | |
1159 | The current interval value. Can be modified any time, but changes only |
1393 | The current interval value. Can be modified any time, but changes only |
1160 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
1394 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
1161 | called. |
1395 | called. |
… | |
… | |
1165 | The current reschedule callback, or C<0>, if this functionality is |
1399 | The current reschedule callback, or C<0>, if this functionality is |
1166 | switched off. Can be changed any time, but changes only take effect when |
1400 | switched off. Can be changed any time, but changes only take effect when |
1167 | the periodic timer fires or C<ev_periodic_again> is being called. |
1401 | the periodic timer fires or C<ev_periodic_again> is being called. |
1168 | |
1402 | |
1169 | =back |
1403 | =back |
|
|
1404 | |
|
|
1405 | =head3 Examples |
1170 | |
1406 | |
1171 | Example: Call a callback every hour, or, more precisely, whenever the |
1407 | Example: Call a callback every hour, or, more precisely, whenever the |
1172 | system clock is divisible by 3600. The callback invocation times have |
1408 | system clock is divisible by 3600. The callback invocation times have |
1173 | potentially a lot of jittering, but good long-term stability. |
1409 | potentially a lot of jittering, but good long-term stability. |
1174 | |
1410 | |
… | |
… | |
1214 | with the kernel (thus it coexists with your own signal handlers as long |
1450 | with the kernel (thus it coexists with your own signal handlers as long |
1215 | as you don't register any with libev). Similarly, when the last signal |
1451 | as you don't register any with libev). Similarly, when the last signal |
1216 | watcher for a signal is stopped libev will reset the signal handler to |
1452 | watcher for a signal is stopped libev will reset the signal handler to |
1217 | SIG_DFL (regardless of what it was set to before). |
1453 | SIG_DFL (regardless of what it was set to before). |
1218 | |
1454 | |
|
|
1455 | If possible and supported, libev will install its handlers with |
|
|
1456 | C<SA_RESTART> behaviour enabled, so syscalls should not be unduly |
|
|
1457 | interrupted. If you have a problem with syscalls getting interrupted by |
|
|
1458 | signals you can block all signals in an C<ev_check> watcher and unblock |
|
|
1459 | them in an C<ev_prepare> watcher. |
|
|
1460 | |
|
|
1461 | =head3 Watcher-Specific Functions and Data Members |
|
|
1462 | |
1219 | =over 4 |
1463 | =over 4 |
1220 | |
1464 | |
1221 | =item ev_signal_init (ev_signal *, callback, int signum) |
1465 | =item ev_signal_init (ev_signal *, callback, int signum) |
1222 | |
1466 | |
1223 | =item ev_signal_set (ev_signal *, int signum) |
1467 | =item ev_signal_set (ev_signal *, int signum) |
… | |
… | |
1229 | |
1473 | |
1230 | The signal the watcher watches out for. |
1474 | The signal the watcher watches out for. |
1231 | |
1475 | |
1232 | =back |
1476 | =back |
1233 | |
1477 | |
|
|
1478 | =head3 Examples |
|
|
1479 | |
|
|
1480 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
|
|
1481 | |
|
|
1482 | static void |
|
|
1483 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
|
|
1484 | { |
|
|
1485 | ev_unloop (loop, EVUNLOOP_ALL); |
|
|
1486 | } |
|
|
1487 | |
|
|
1488 | struct ev_signal signal_watcher; |
|
|
1489 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
|
|
1490 | ev_signal_start (loop, &sigint_cb); |
|
|
1491 | |
1234 | |
1492 | |
1235 | =head2 C<ev_child> - watch out for process status changes |
1493 | =head2 C<ev_child> - watch out for process status changes |
1236 | |
1494 | |
1237 | Child watchers trigger when your process receives a SIGCHLD in response to |
1495 | Child watchers trigger when your process receives a SIGCHLD in response to |
1238 | some child status changes (most typically when a child of yours dies). |
1496 | some child status changes (most typically when a child of yours dies). It |
|
|
1497 | is permissible to install a child watcher I<after> the child has been |
|
|
1498 | forked (which implies it might have already exited), as long as the event |
|
|
1499 | loop isn't entered (or is continued from a watcher). |
|
|
1500 | |
|
|
1501 | Only the default event loop is capable of handling signals, and therefore |
|
|
1502 | you can only rgeister child watchers in the default event loop. |
|
|
1503 | |
|
|
1504 | =head3 Process Interaction |
|
|
1505 | |
|
|
1506 | Libev grabs C<SIGCHLD> as soon as the default event loop is |
|
|
1507 | initialised. This is necessary to guarantee proper behaviour even if |
|
|
1508 | the first child watcher is started after the child exits. The occurance |
|
|
1509 | of C<SIGCHLD> is recorded asynchronously, but child reaping is done |
|
|
1510 | synchronously as part of the event loop processing. Libev always reaps all |
|
|
1511 | children, even ones not watched. |
|
|
1512 | |
|
|
1513 | =head3 Overriding the Built-In Processing |
|
|
1514 | |
|
|
1515 | Libev offers no special support for overriding the built-in child |
|
|
1516 | processing, but if your application collides with libev's default child |
|
|
1517 | handler, you can override it easily by installing your own handler for |
|
|
1518 | C<SIGCHLD> after initialising the default loop, and making sure the |
|
|
1519 | default loop never gets destroyed. You are encouraged, however, to use an |
|
|
1520 | event-based approach to child reaping and thus use libev's support for |
|
|
1521 | that, so other libev users can use C<ev_child> watchers freely. |
|
|
1522 | |
|
|
1523 | =head3 Watcher-Specific Functions and Data Members |
1239 | |
1524 | |
1240 | =over 4 |
1525 | =over 4 |
1241 | |
1526 | |
1242 | =item ev_child_init (ev_child *, callback, int pid) |
1527 | =item ev_child_init (ev_child *, callback, int pid, int trace) |
1243 | |
1528 | |
1244 | =item ev_child_set (ev_child *, int pid) |
1529 | =item ev_child_set (ev_child *, int pid, int trace) |
1245 | |
1530 | |
1246 | Configures the watcher to wait for status changes of process C<pid> (or |
1531 | Configures the watcher to wait for status changes of process C<pid> (or |
1247 | I<any> process if C<pid> is specified as C<0>). The callback can look |
1532 | I<any> process if C<pid> is specified as C<0>). The callback can look |
1248 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
1533 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
1249 | the status word (use the macros from C<sys/wait.h> and see your systems |
1534 | the status word (use the macros from C<sys/wait.h> and see your systems |
1250 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
1535 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
1251 | process causing the status change. |
1536 | process causing the status change. C<trace> must be either C<0> (only |
|
|
1537 | activate the watcher when the process terminates) or C<1> (additionally |
|
|
1538 | activate the watcher when the process is stopped or continued). |
1252 | |
1539 | |
1253 | =item int pid [read-only] |
1540 | =item int pid [read-only] |
1254 | |
1541 | |
1255 | The process id this watcher watches out for, or C<0>, meaning any process id. |
1542 | The process id this watcher watches out for, or C<0>, meaning any process id. |
1256 | |
1543 | |
… | |
… | |
1263 | The process exit/trace status caused by C<rpid> (see your systems |
1550 | The process exit/trace status caused by C<rpid> (see your systems |
1264 | C<waitpid> and C<sys/wait.h> documentation for details). |
1551 | C<waitpid> and C<sys/wait.h> documentation for details). |
1265 | |
1552 | |
1266 | =back |
1553 | =back |
1267 | |
1554 | |
1268 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
1555 | =head3 Examples |
|
|
1556 | |
|
|
1557 | Example: C<fork()> a new process and install a child handler to wait for |
|
|
1558 | its completion. |
|
|
1559 | |
|
|
1560 | ev_child cw; |
1269 | |
1561 | |
1270 | static void |
1562 | static void |
1271 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1563 | child_cb (EV_P_ struct ev_child *w, int revents) |
1272 | { |
1564 | { |
1273 | ev_unloop (loop, EVUNLOOP_ALL); |
1565 | ev_child_stop (EV_A_ w); |
|
|
1566 | printf ("process %d exited with status %x\n", w->rpid, w->rstatus); |
1274 | } |
1567 | } |
1275 | |
1568 | |
1276 | struct ev_signal signal_watcher; |
1569 | pid_t pid = fork (); |
1277 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1570 | |
1278 | ev_signal_start (loop, &sigint_cb); |
1571 | if (pid < 0) |
|
|
1572 | // error |
|
|
1573 | else if (pid == 0) |
|
|
1574 | { |
|
|
1575 | // the forked child executes here |
|
|
1576 | exit (1); |
|
|
1577 | } |
|
|
1578 | else |
|
|
1579 | { |
|
|
1580 | ev_child_init (&cw, child_cb, pid, 0); |
|
|
1581 | ev_child_start (EV_DEFAULT_ &cw); |
|
|
1582 | } |
1279 | |
1583 | |
1280 | |
1584 | |
1281 | =head2 C<ev_stat> - did the file attributes just change? |
1585 | =head2 C<ev_stat> - did the file attributes just change? |
1282 | |
1586 | |
1283 | This watches a filesystem path for attribute changes. That is, it calls |
1587 | This watches a filesystem path for attribute changes. That is, it calls |
… | |
… | |
1306 | as even with OS-supported change notifications, this can be |
1610 | as even with OS-supported change notifications, this can be |
1307 | resource-intensive. |
1611 | resource-intensive. |
1308 | |
1612 | |
1309 | At the time of this writing, only the Linux inotify interface is |
1613 | At the time of this writing, only the Linux inotify interface is |
1310 | implemented (implementing kqueue support is left as an exercise for the |
1614 | implemented (implementing kqueue support is left as an exercise for the |
|
|
1615 | reader, note, however, that the author sees no way of implementing ev_stat |
1311 | reader). Inotify will be used to give hints only and should not change the |
1616 | semantics with kqueue). Inotify will be used to give hints only and should |
1312 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
1617 | not change the semantics of C<ev_stat> watchers, which means that libev |
1313 | to fall back to regular polling again even with inotify, but changes are |
1618 | sometimes needs to fall back to regular polling again even with inotify, |
1314 | usually detected immediately, and if the file exists there will be no |
1619 | but changes are usually detected immediately, and if the file exists there |
1315 | polling. |
1620 | will be no polling. |
|
|
1621 | |
|
|
1622 | =head3 ABI Issues (Largefile Support) |
|
|
1623 | |
|
|
1624 | Libev by default (unless the user overrides this) uses the default |
|
|
1625 | compilation environment, which means that on systems with optionally |
|
|
1626 | disabled large file support, you get the 32 bit version of the stat |
|
|
1627 | structure. When using the library from programs that change the ABI to |
|
|
1628 | use 64 bit file offsets the programs will fail. In that case you have to |
|
|
1629 | compile libev with the same flags to get binary compatibility. This is |
|
|
1630 | obviously the case with any flags that change the ABI, but the problem is |
|
|
1631 | most noticably with ev_stat and largefile support. |
|
|
1632 | |
|
|
1633 | =head3 Inotify |
|
|
1634 | |
|
|
1635 | When C<inotify (7)> support has been compiled into libev (generally only |
|
|
1636 | available on Linux) and present at runtime, it will be used to speed up |
|
|
1637 | change detection where possible. The inotify descriptor will be created lazily |
|
|
1638 | when the first C<ev_stat> watcher is being started. |
|
|
1639 | |
|
|
1640 | Inotify presence does not change the semantics of C<ev_stat> watchers |
|
|
1641 | except that changes might be detected earlier, and in some cases, to avoid |
|
|
1642 | making regular C<stat> calls. Even in the presence of inotify support |
|
|
1643 | there are many cases where libev has to resort to regular C<stat> polling. |
|
|
1644 | |
|
|
1645 | (There is no support for kqueue, as apparently it cannot be used to |
|
|
1646 | implement this functionality, due to the requirement of having a file |
|
|
1647 | descriptor open on the object at all times). |
|
|
1648 | |
|
|
1649 | =head3 The special problem of stat time resolution |
|
|
1650 | |
|
|
1651 | The C<stat ()> syscall only supports full-second resolution portably, and |
|
|
1652 | even on systems where the resolution is higher, many filesystems still |
|
|
1653 | only support whole seconds. |
|
|
1654 | |
|
|
1655 | That means that, if the time is the only thing that changes, you can |
|
|
1656 | easily miss updates: on the first update, C<ev_stat> detects a change and |
|
|
1657 | calls your callback, which does something. When there is another update |
|
|
1658 | within the same second, C<ev_stat> will be unable to detect it as the stat |
|
|
1659 | data does not change. |
|
|
1660 | |
|
|
1661 | The solution to this is to delay acting on a change for slightly more |
|
|
1662 | than second (or till slightly after the next full second boundary), using |
|
|
1663 | a roughly one-second-delay C<ev_timer> (e.g. C<ev_timer_set (w, 0., 1.02); |
|
|
1664 | ev_timer_again (loop, w)>). |
|
|
1665 | |
|
|
1666 | The C<.02> offset is added to work around small timing inconsistencies |
|
|
1667 | of some operating systems (where the second counter of the current time |
|
|
1668 | might be be delayed. One such system is the Linux kernel, where a call to |
|
|
1669 | C<gettimeofday> might return a timestamp with a full second later than |
|
|
1670 | a subsequent C<time> call - if the equivalent of C<time ()> is used to |
|
|
1671 | update file times then there will be a small window where the kernel uses |
|
|
1672 | the previous second to update file times but libev might already execute |
|
|
1673 | the timer callback). |
|
|
1674 | |
|
|
1675 | =head3 Watcher-Specific Functions and Data Members |
1316 | |
1676 | |
1317 | =over 4 |
1677 | =over 4 |
1318 | |
1678 | |
1319 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1679 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1320 | |
1680 | |
… | |
… | |
1324 | C<path>. The C<interval> is a hint on how quickly a change is expected to |
1684 | C<path>. The C<interval> is a hint on how quickly a change is expected to |
1325 | be detected and should normally be specified as C<0> to let libev choose |
1685 | be detected and should normally be specified as C<0> to let libev choose |
1326 | a suitable value. The memory pointed to by C<path> must point to the same |
1686 | a suitable value. The memory pointed to by C<path> must point to the same |
1327 | path for as long as the watcher is active. |
1687 | path for as long as the watcher is active. |
1328 | |
1688 | |
1329 | The callback will be receive C<EV_STAT> when a change was detected, |
1689 | The callback will receive C<EV_STAT> when a change was detected, relative |
1330 | relative to the attributes at the time the watcher was started (or the |
1690 | to the attributes at the time the watcher was started (or the last change |
1331 | last change was detected). |
1691 | was detected). |
1332 | |
1692 | |
1333 | =item ev_stat_stat (ev_stat *) |
1693 | =item ev_stat_stat (loop, ev_stat *) |
1334 | |
1694 | |
1335 | Updates the stat buffer immediately with new values. If you change the |
1695 | Updates the stat buffer immediately with new values. If you change the |
1336 | watched path in your callback, you could call this fucntion to avoid |
1696 | watched path in your callback, you could call this function to avoid |
1337 | detecting this change (while introducing a race condition). Can also be |
1697 | detecting this change (while introducing a race condition if you are not |
1338 | useful simply to find out the new values. |
1698 | the only one changing the path). Can also be useful simply to find out the |
|
|
1699 | new values. |
1339 | |
1700 | |
1340 | =item ev_statdata attr [read-only] |
1701 | =item ev_statdata attr [read-only] |
1341 | |
1702 | |
1342 | The most-recently detected attributes of the file. Although the type is of |
1703 | The most-recently detected attributes of the file. Although the type is |
1343 | C<ev_statdata>, this is usually the (or one of the) C<struct stat> types |
1704 | C<ev_statdata>, this is usually the (or one of the) C<struct stat> types |
1344 | suitable for your system. If the C<st_nlink> member is C<0>, then there |
1705 | suitable for your system, but you can only rely on the POSIX-standardised |
|
|
1706 | members to be present. If the C<st_nlink> member is C<0>, then there was |
1345 | was some error while C<stat>ing the file. |
1707 | some error while C<stat>ing the file. |
1346 | |
1708 | |
1347 | =item ev_statdata prev [read-only] |
1709 | =item ev_statdata prev [read-only] |
1348 | |
1710 | |
1349 | The previous attributes of the file. The callback gets invoked whenever |
1711 | The previous attributes of the file. The callback gets invoked whenever |
1350 | C<prev> != C<attr>. |
1712 | C<prev> != C<attr>, or, more precisely, one or more of these members |
|
|
1713 | differ: C<st_dev>, C<st_ino>, C<st_mode>, C<st_nlink>, C<st_uid>, |
|
|
1714 | C<st_gid>, C<st_rdev>, C<st_size>, C<st_atime>, C<st_mtime>, C<st_ctime>. |
1351 | |
1715 | |
1352 | =item ev_tstamp interval [read-only] |
1716 | =item ev_tstamp interval [read-only] |
1353 | |
1717 | |
1354 | The specified interval. |
1718 | The specified interval. |
1355 | |
1719 | |
1356 | =item const char *path [read-only] |
1720 | =item const char *path [read-only] |
1357 | |
1721 | |
1358 | The filesystem path that is being watched. |
1722 | The filesystem path that is being watched. |
1359 | |
1723 | |
1360 | =back |
1724 | =back |
|
|
1725 | |
|
|
1726 | =head3 Examples |
1361 | |
1727 | |
1362 | Example: Watch C</etc/passwd> for attribute changes. |
1728 | Example: Watch C</etc/passwd> for attribute changes. |
1363 | |
1729 | |
1364 | static void |
1730 | static void |
1365 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
1731 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
… | |
… | |
1378 | } |
1744 | } |
1379 | |
1745 | |
1380 | ... |
1746 | ... |
1381 | ev_stat passwd; |
1747 | ev_stat passwd; |
1382 | |
1748 | |
1383 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd"); |
1749 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.); |
1384 | ev_stat_start (loop, &passwd); |
1750 | ev_stat_start (loop, &passwd); |
|
|
1751 | |
|
|
1752 | Example: Like above, but additionally use a one-second delay so we do not |
|
|
1753 | miss updates (however, frequent updates will delay processing, too, so |
|
|
1754 | one might do the work both on C<ev_stat> callback invocation I<and> on |
|
|
1755 | C<ev_timer> callback invocation). |
|
|
1756 | |
|
|
1757 | static ev_stat passwd; |
|
|
1758 | static ev_timer timer; |
|
|
1759 | |
|
|
1760 | static void |
|
|
1761 | timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1762 | { |
|
|
1763 | ev_timer_stop (EV_A_ w); |
|
|
1764 | |
|
|
1765 | /* now it's one second after the most recent passwd change */ |
|
|
1766 | } |
|
|
1767 | |
|
|
1768 | static void |
|
|
1769 | stat_cb (EV_P_ ev_stat *w, int revents) |
|
|
1770 | { |
|
|
1771 | /* reset the one-second timer */ |
|
|
1772 | ev_timer_again (EV_A_ &timer); |
|
|
1773 | } |
|
|
1774 | |
|
|
1775 | ... |
|
|
1776 | ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); |
|
|
1777 | ev_stat_start (loop, &passwd); |
|
|
1778 | ev_timer_init (&timer, timer_cb, 0., 1.02); |
1385 | |
1779 | |
1386 | |
1780 | |
1387 | =head2 C<ev_idle> - when you've got nothing better to do... |
1781 | =head2 C<ev_idle> - when you've got nothing better to do... |
1388 | |
1782 | |
1389 | Idle watchers trigger events when no other events of the same or higher |
1783 | Idle watchers trigger events when no other events of the same or higher |
… | |
… | |
1403 | Apart from keeping your process non-blocking (which is a useful |
1797 | Apart from keeping your process non-blocking (which is a useful |
1404 | effect on its own sometimes), idle watchers are a good place to do |
1798 | effect on its own sometimes), idle watchers are a good place to do |
1405 | "pseudo-background processing", or delay processing stuff to after the |
1799 | "pseudo-background processing", or delay processing stuff to after the |
1406 | event loop has handled all outstanding events. |
1800 | event loop has handled all outstanding events. |
1407 | |
1801 | |
|
|
1802 | =head3 Watcher-Specific Functions and Data Members |
|
|
1803 | |
1408 | =over 4 |
1804 | =over 4 |
1409 | |
1805 | |
1410 | =item ev_idle_init (ev_signal *, callback) |
1806 | =item ev_idle_init (ev_signal *, callback) |
1411 | |
1807 | |
1412 | Initialises and configures the idle watcher - it has no parameters of any |
1808 | Initialises and configures the idle watcher - it has no parameters of any |
1413 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1809 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1414 | believe me. |
1810 | believe me. |
1415 | |
1811 | |
1416 | =back |
1812 | =back |
|
|
1813 | |
|
|
1814 | =head3 Examples |
1417 | |
1815 | |
1418 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1816 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1419 | callback, free it. Also, use no error checking, as usual. |
1817 | callback, free it. Also, use no error checking, as usual. |
1420 | |
1818 | |
1421 | static void |
1819 | static void |
1422 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1820 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1423 | { |
1821 | { |
1424 | free (w); |
1822 | free (w); |
1425 | // now do something you wanted to do when the program has |
1823 | // now do something you wanted to do when the program has |
1426 | // no longer asnything immediate to do. |
1824 | // no longer anything immediate to do. |
1427 | } |
1825 | } |
1428 | |
1826 | |
1429 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1827 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1430 | ev_idle_init (idle_watcher, idle_cb); |
1828 | ev_idle_init (idle_watcher, idle_cb); |
1431 | ev_idle_start (loop, idle_cb); |
1829 | ev_idle_start (loop, idle_cb); |
… | |
… | |
1469 | with priority higher than or equal to the event loop and one coroutine |
1867 | with priority higher than or equal to the event loop and one coroutine |
1470 | of lower priority, but only once, using idle watchers to keep the event |
1868 | of lower priority, but only once, using idle watchers to keep the event |
1471 | loop from blocking if lower-priority coroutines are active, thus mapping |
1869 | loop from blocking if lower-priority coroutines are active, thus mapping |
1472 | low-priority coroutines to idle/background tasks). |
1870 | low-priority coroutines to idle/background tasks). |
1473 | |
1871 | |
|
|
1872 | It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>) |
|
|
1873 | priority, to ensure that they are being run before any other watchers |
|
|
1874 | after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers, |
|
|
1875 | too) should not activate ("feed") events into libev. While libev fully |
|
|
1876 | supports this, they might get executed before other C<ev_check> watchers |
|
|
1877 | did their job. As C<ev_check> watchers are often used to embed other |
|
|
1878 | (non-libev) event loops those other event loops might be in an unusable |
|
|
1879 | state until their C<ev_check> watcher ran (always remind yourself to |
|
|
1880 | coexist peacefully with others). |
|
|
1881 | |
|
|
1882 | =head3 Watcher-Specific Functions and Data Members |
|
|
1883 | |
1474 | =over 4 |
1884 | =over 4 |
1475 | |
1885 | |
1476 | =item ev_prepare_init (ev_prepare *, callback) |
1886 | =item ev_prepare_init (ev_prepare *, callback) |
1477 | |
1887 | |
1478 | =item ev_check_init (ev_check *, callback) |
1888 | =item ev_check_init (ev_check *, callback) |
… | |
… | |
1481 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1891 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1482 | macros, but using them is utterly, utterly and completely pointless. |
1892 | macros, but using them is utterly, utterly and completely pointless. |
1483 | |
1893 | |
1484 | =back |
1894 | =back |
1485 | |
1895 | |
1486 | Example: To include a library such as adns, you would add IO watchers |
1896 | =head3 Examples |
1487 | and a timeout watcher in a prepare handler, as required by libadns, and |
1897 | |
|
|
1898 | There are a number of principal ways to embed other event loops or modules |
|
|
1899 | into libev. Here are some ideas on how to include libadns into libev |
|
|
1900 | (there is a Perl module named C<EV::ADNS> that does this, which you could |
|
|
1901 | use as a working example. Another Perl module named C<EV::Glib> embeds a |
|
|
1902 | Glib main context into libev, and finally, C<Glib::EV> embeds EV into the |
|
|
1903 | Glib event loop). |
|
|
1904 | |
|
|
1905 | Method 1: Add IO watchers and a timeout watcher in a prepare handler, |
1488 | in a check watcher, destroy them and call into libadns. What follows is |
1906 | and in a check watcher, destroy them and call into libadns. What follows |
1489 | pseudo-code only of course: |
1907 | is pseudo-code only of course. This requires you to either use a low |
|
|
1908 | priority for the check watcher or use C<ev_clear_pending> explicitly, as |
|
|
1909 | the callbacks for the IO/timeout watchers might not have been called yet. |
1490 | |
1910 | |
1491 | static ev_io iow [nfd]; |
1911 | static ev_io iow [nfd]; |
1492 | static ev_timer tw; |
1912 | static ev_timer tw; |
1493 | |
1913 | |
1494 | static void |
1914 | static void |
1495 | io_cb (ev_loop *loop, ev_io *w, int revents) |
1915 | io_cb (ev_loop *loop, ev_io *w, int revents) |
1496 | { |
1916 | { |
1497 | // set the relevant poll flags |
|
|
1498 | // could also call adns_processreadable etc. here |
|
|
1499 | struct pollfd *fd = (struct pollfd *)w->data; |
|
|
1500 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1501 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1502 | } |
1917 | } |
1503 | |
1918 | |
1504 | // create io watchers for each fd and a timer before blocking |
1919 | // create io watchers for each fd and a timer before blocking |
1505 | static void |
1920 | static void |
1506 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1921 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
… | |
… | |
1512 | |
1927 | |
1513 | /* the callback is illegal, but won't be called as we stop during check */ |
1928 | /* the callback is illegal, but won't be called as we stop during check */ |
1514 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1929 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1515 | ev_timer_start (loop, &tw); |
1930 | ev_timer_start (loop, &tw); |
1516 | |
1931 | |
1517 | // create on ev_io per pollfd |
1932 | // create one ev_io per pollfd |
1518 | for (int i = 0; i < nfd; ++i) |
1933 | for (int i = 0; i < nfd; ++i) |
1519 | { |
1934 | { |
1520 | ev_io_init (iow + i, io_cb, fds [i].fd, |
1935 | ev_io_init (iow + i, io_cb, fds [i].fd, |
1521 | ((fds [i].events & POLLIN ? EV_READ : 0) |
1936 | ((fds [i].events & POLLIN ? EV_READ : 0) |
1522 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1937 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1523 | |
1938 | |
1524 | fds [i].revents = 0; |
1939 | fds [i].revents = 0; |
1525 | iow [i].data = fds + i; |
|
|
1526 | ev_io_start (loop, iow + i); |
1940 | ev_io_start (loop, iow + i); |
1527 | } |
1941 | } |
1528 | } |
1942 | } |
1529 | |
1943 | |
1530 | // stop all watchers after blocking |
1944 | // stop all watchers after blocking |
… | |
… | |
1532 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
1946 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
1533 | { |
1947 | { |
1534 | ev_timer_stop (loop, &tw); |
1948 | ev_timer_stop (loop, &tw); |
1535 | |
1949 | |
1536 | for (int i = 0; i < nfd; ++i) |
1950 | for (int i = 0; i < nfd; ++i) |
|
|
1951 | { |
|
|
1952 | // set the relevant poll flags |
|
|
1953 | // could also call adns_processreadable etc. here |
|
|
1954 | struct pollfd *fd = fds + i; |
|
|
1955 | int revents = ev_clear_pending (iow + i); |
|
|
1956 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1957 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1958 | |
|
|
1959 | // now stop the watcher |
1537 | ev_io_stop (loop, iow + i); |
1960 | ev_io_stop (loop, iow + i); |
|
|
1961 | } |
1538 | |
1962 | |
1539 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
1963 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
1964 | } |
|
|
1965 | |
|
|
1966 | Method 2: This would be just like method 1, but you run C<adns_afterpoll> |
|
|
1967 | in the prepare watcher and would dispose of the check watcher. |
|
|
1968 | |
|
|
1969 | Method 3: If the module to be embedded supports explicit event |
|
|
1970 | notification (adns does), you can also make use of the actual watcher |
|
|
1971 | callbacks, and only destroy/create the watchers in the prepare watcher. |
|
|
1972 | |
|
|
1973 | static void |
|
|
1974 | timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1975 | { |
|
|
1976 | adns_state ads = (adns_state)w->data; |
|
|
1977 | update_now (EV_A); |
|
|
1978 | |
|
|
1979 | adns_processtimeouts (ads, &tv_now); |
|
|
1980 | } |
|
|
1981 | |
|
|
1982 | static void |
|
|
1983 | io_cb (EV_P_ ev_io *w, int revents) |
|
|
1984 | { |
|
|
1985 | adns_state ads = (adns_state)w->data; |
|
|
1986 | update_now (EV_A); |
|
|
1987 | |
|
|
1988 | if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now); |
|
|
1989 | if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now); |
|
|
1990 | } |
|
|
1991 | |
|
|
1992 | // do not ever call adns_afterpoll |
|
|
1993 | |
|
|
1994 | Method 4: Do not use a prepare or check watcher because the module you |
|
|
1995 | want to embed is too inflexible to support it. Instead, youc na override |
|
|
1996 | their poll function. The drawback with this solution is that the main |
|
|
1997 | loop is now no longer controllable by EV. The C<Glib::EV> module does |
|
|
1998 | this. |
|
|
1999 | |
|
|
2000 | static gint |
|
|
2001 | event_poll_func (GPollFD *fds, guint nfds, gint timeout) |
|
|
2002 | { |
|
|
2003 | int got_events = 0; |
|
|
2004 | |
|
|
2005 | for (n = 0; n < nfds; ++n) |
|
|
2006 | // create/start io watcher that sets the relevant bits in fds[n] and increment got_events |
|
|
2007 | |
|
|
2008 | if (timeout >= 0) |
|
|
2009 | // create/start timer |
|
|
2010 | |
|
|
2011 | // poll |
|
|
2012 | ev_loop (EV_A_ 0); |
|
|
2013 | |
|
|
2014 | // stop timer again |
|
|
2015 | if (timeout >= 0) |
|
|
2016 | ev_timer_stop (EV_A_ &to); |
|
|
2017 | |
|
|
2018 | // stop io watchers again - their callbacks should have set |
|
|
2019 | for (n = 0; n < nfds; ++n) |
|
|
2020 | ev_io_stop (EV_A_ iow [n]); |
|
|
2021 | |
|
|
2022 | return got_events; |
1540 | } |
2023 | } |
1541 | |
2024 | |
1542 | |
2025 | |
1543 | =head2 C<ev_embed> - when one backend isn't enough... |
2026 | =head2 C<ev_embed> - when one backend isn't enough... |
1544 | |
2027 | |
… | |
… | |
1587 | portable one. |
2070 | portable one. |
1588 | |
2071 | |
1589 | So when you want to use this feature you will always have to be prepared |
2072 | So when you want to use this feature you will always have to be prepared |
1590 | that you cannot get an embeddable loop. The recommended way to get around |
2073 | that you cannot get an embeddable loop. The recommended way to get around |
1591 | this is to have a separate variables for your embeddable loop, try to |
2074 | this is to have a separate variables for your embeddable loop, try to |
1592 | create it, and if that fails, use the normal loop for everything: |
2075 | create it, and if that fails, use the normal loop for everything. |
|
|
2076 | |
|
|
2077 | =head3 Watcher-Specific Functions and Data Members |
|
|
2078 | |
|
|
2079 | =over 4 |
|
|
2080 | |
|
|
2081 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
2082 | |
|
|
2083 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
2084 | |
|
|
2085 | Configures the watcher to embed the given loop, which must be |
|
|
2086 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
|
|
2087 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
2088 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
2089 | if you do not want thta, you need to temporarily stop the embed watcher). |
|
|
2090 | |
|
|
2091 | =item ev_embed_sweep (loop, ev_embed *) |
|
|
2092 | |
|
|
2093 | Make a single, non-blocking sweep over the embedded loop. This works |
|
|
2094 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
|
|
2095 | apropriate way for embedded loops. |
|
|
2096 | |
|
|
2097 | =item struct ev_loop *other [read-only] |
|
|
2098 | |
|
|
2099 | The embedded event loop. |
|
|
2100 | |
|
|
2101 | =back |
|
|
2102 | |
|
|
2103 | =head3 Examples |
|
|
2104 | |
|
|
2105 | Example: Try to get an embeddable event loop and embed it into the default |
|
|
2106 | event loop. If that is not possible, use the default loop. The default |
|
|
2107 | loop is stored in C<loop_hi>, while the mebeddable loop is stored in |
|
|
2108 | C<loop_lo> (which is C<loop_hi> in the acse no embeddable loop can be |
|
|
2109 | used). |
1593 | |
2110 | |
1594 | struct ev_loop *loop_hi = ev_default_init (0); |
2111 | struct ev_loop *loop_hi = ev_default_init (0); |
1595 | struct ev_loop *loop_lo = 0; |
2112 | struct ev_loop *loop_lo = 0; |
1596 | struct ev_embed embed; |
2113 | struct ev_embed embed; |
1597 | |
2114 | |
… | |
… | |
1608 | ev_embed_start (loop_hi, &embed); |
2125 | ev_embed_start (loop_hi, &embed); |
1609 | } |
2126 | } |
1610 | else |
2127 | else |
1611 | loop_lo = loop_hi; |
2128 | loop_lo = loop_hi; |
1612 | |
2129 | |
1613 | =over 4 |
2130 | Example: Check if kqueue is available but not recommended and create |
|
|
2131 | a kqueue backend for use with sockets (which usually work with any |
|
|
2132 | kqueue implementation). Store the kqueue/socket-only event loop in |
|
|
2133 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
1614 | |
2134 | |
1615 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
2135 | struct ev_loop *loop = ev_default_init (0); |
|
|
2136 | struct ev_loop *loop_socket = 0; |
|
|
2137 | struct ev_embed embed; |
|
|
2138 | |
|
|
2139 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
|
|
2140 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
|
|
2141 | { |
|
|
2142 | ev_embed_init (&embed, 0, loop_socket); |
|
|
2143 | ev_embed_start (loop, &embed); |
|
|
2144 | } |
1616 | |
2145 | |
1617 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
2146 | if (!loop_socket) |
|
|
2147 | loop_socket = loop; |
1618 | |
2148 | |
1619 | Configures the watcher to embed the given loop, which must be |
2149 | // now use loop_socket for all sockets, and loop for everything else |
1620 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
|
|
1621 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
1622 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
1623 | if you do not want thta, you need to temporarily stop the embed watcher). |
|
|
1624 | |
|
|
1625 | =item ev_embed_sweep (loop, ev_embed *) |
|
|
1626 | |
|
|
1627 | Make a single, non-blocking sweep over the embedded loop. This works |
|
|
1628 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
|
|
1629 | apropriate way for embedded loops. |
|
|
1630 | |
|
|
1631 | =item struct ev_loop *loop [read-only] |
|
|
1632 | |
|
|
1633 | The embedded event loop. |
|
|
1634 | |
|
|
1635 | =back |
|
|
1636 | |
2150 | |
1637 | |
2151 | |
1638 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
2152 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
1639 | |
2153 | |
1640 | Fork watchers are called when a C<fork ()> was detected (usually because |
2154 | Fork watchers are called when a C<fork ()> was detected (usually because |
… | |
… | |
1643 | event loop blocks next and before C<ev_check> watchers are being called, |
2157 | event loop blocks next and before C<ev_check> watchers are being called, |
1644 | and only in the child after the fork. If whoever good citizen calling |
2158 | and only in the child after the fork. If whoever good citizen calling |
1645 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
2159 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
1646 | handlers will be invoked, too, of course. |
2160 | handlers will be invoked, too, of course. |
1647 | |
2161 | |
|
|
2162 | =head3 Watcher-Specific Functions and Data Members |
|
|
2163 | |
1648 | =over 4 |
2164 | =over 4 |
1649 | |
2165 | |
1650 | =item ev_fork_init (ev_signal *, callback) |
2166 | =item ev_fork_init (ev_signal *, callback) |
1651 | |
2167 | |
1652 | Initialises and configures the fork watcher - it has no parameters of any |
2168 | Initialises and configures the fork watcher - it has no parameters of any |
1653 | kind. There is a C<ev_fork_set> macro, but using it is utterly pointless, |
2169 | kind. There is a C<ev_fork_set> macro, but using it is utterly pointless, |
1654 | believe me. |
2170 | believe me. |
|
|
2171 | |
|
|
2172 | =back |
|
|
2173 | |
|
|
2174 | |
|
|
2175 | =head2 C<ev_async> - how to wake up another event loop |
|
|
2176 | |
|
|
2177 | In general, you cannot use an C<ev_loop> from multiple threads or other |
|
|
2178 | asynchronous sources such as signal handlers (as opposed to multiple event |
|
|
2179 | loops - those are of course safe to use in different threads). |
|
|
2180 | |
|
|
2181 | Sometimes, however, you need to wake up another event loop you do not |
|
|
2182 | control, for example because it belongs to another thread. This is what |
|
|
2183 | C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you |
|
|
2184 | can signal it by calling C<ev_async_send>, which is thread- and signal |
|
|
2185 | safe. |
|
|
2186 | |
|
|
2187 | This functionality is very similar to C<ev_signal> watchers, as signals, |
|
|
2188 | too, are asynchronous in nature, and signals, too, will be compressed |
|
|
2189 | (i.e. the number of callback invocations may be less than the number of |
|
|
2190 | C<ev_async_sent> calls). |
|
|
2191 | |
|
|
2192 | Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not |
|
|
2193 | just the default loop. |
|
|
2194 | |
|
|
2195 | =head3 Queueing |
|
|
2196 | |
|
|
2197 | C<ev_async> does not support queueing of data in any way. The reason |
|
|
2198 | is that the author does not know of a simple (or any) algorithm for a |
|
|
2199 | multiple-writer-single-reader queue that works in all cases and doesn't |
|
|
2200 | need elaborate support such as pthreads. |
|
|
2201 | |
|
|
2202 | That means that if you want to queue data, you have to provide your own |
|
|
2203 | queue. But at least I can tell you would implement locking around your |
|
|
2204 | queue: |
|
|
2205 | |
|
|
2206 | =over 4 |
|
|
2207 | |
|
|
2208 | =item queueing from a signal handler context |
|
|
2209 | |
|
|
2210 | To implement race-free queueing, you simply add to the queue in the signal |
|
|
2211 | handler but you block the signal handler in the watcher callback. Here is an example that does that for |
|
|
2212 | some fictitiuous SIGUSR1 handler: |
|
|
2213 | |
|
|
2214 | static ev_async mysig; |
|
|
2215 | |
|
|
2216 | static void |
|
|
2217 | sigusr1_handler (void) |
|
|
2218 | { |
|
|
2219 | sometype data; |
|
|
2220 | |
|
|
2221 | // no locking etc. |
|
|
2222 | queue_put (data); |
|
|
2223 | ev_async_send (EV_DEFAULT_ &mysig); |
|
|
2224 | } |
|
|
2225 | |
|
|
2226 | static void |
|
|
2227 | mysig_cb (EV_P_ ev_async *w, int revents) |
|
|
2228 | { |
|
|
2229 | sometype data; |
|
|
2230 | sigset_t block, prev; |
|
|
2231 | |
|
|
2232 | sigemptyset (&block); |
|
|
2233 | sigaddset (&block, SIGUSR1); |
|
|
2234 | sigprocmask (SIG_BLOCK, &block, &prev); |
|
|
2235 | |
|
|
2236 | while (queue_get (&data)) |
|
|
2237 | process (data); |
|
|
2238 | |
|
|
2239 | if (sigismember (&prev, SIGUSR1) |
|
|
2240 | sigprocmask (SIG_UNBLOCK, &block, 0); |
|
|
2241 | } |
|
|
2242 | |
|
|
2243 | (Note: pthreads in theory requires you to use C<pthread_setmask> |
|
|
2244 | instead of C<sigprocmask> when you use threads, but libev doesn't do it |
|
|
2245 | either...). |
|
|
2246 | |
|
|
2247 | =item queueing from a thread context |
|
|
2248 | |
|
|
2249 | The strategy for threads is different, as you cannot (easily) block |
|
|
2250 | threads but you can easily preempt them, so to queue safely you need to |
|
|
2251 | employ a traditional mutex lock, such as in this pthread example: |
|
|
2252 | |
|
|
2253 | static ev_async mysig; |
|
|
2254 | static pthread_mutex_t mymutex = PTHREAD_MUTEX_INITIALIZER; |
|
|
2255 | |
|
|
2256 | static void |
|
|
2257 | otherthread (void) |
|
|
2258 | { |
|
|
2259 | // only need to lock the actual queueing operation |
|
|
2260 | pthread_mutex_lock (&mymutex); |
|
|
2261 | queue_put (data); |
|
|
2262 | pthread_mutex_unlock (&mymutex); |
|
|
2263 | |
|
|
2264 | ev_async_send (EV_DEFAULT_ &mysig); |
|
|
2265 | } |
|
|
2266 | |
|
|
2267 | static void |
|
|
2268 | mysig_cb (EV_P_ ev_async *w, int revents) |
|
|
2269 | { |
|
|
2270 | pthread_mutex_lock (&mymutex); |
|
|
2271 | |
|
|
2272 | while (queue_get (&data)) |
|
|
2273 | process (data); |
|
|
2274 | |
|
|
2275 | pthread_mutex_unlock (&mymutex); |
|
|
2276 | } |
|
|
2277 | |
|
|
2278 | =back |
|
|
2279 | |
|
|
2280 | |
|
|
2281 | =head3 Watcher-Specific Functions and Data Members |
|
|
2282 | |
|
|
2283 | =over 4 |
|
|
2284 | |
|
|
2285 | =item ev_async_init (ev_async *, callback) |
|
|
2286 | |
|
|
2287 | Initialises and configures the async watcher - it has no parameters of any |
|
|
2288 | kind. There is a C<ev_asynd_set> macro, but using it is utterly pointless, |
|
|
2289 | believe me. |
|
|
2290 | |
|
|
2291 | =item ev_async_send (loop, ev_async *) |
|
|
2292 | |
|
|
2293 | Sends/signals/activates the given C<ev_async> watcher, that is, feeds |
|
|
2294 | an C<EV_ASYNC> event on the watcher into the event loop. Unlike |
|
|
2295 | C<ev_feed_event>, this call is safe to do in other threads, signal or |
|
|
2296 | similar contexts (see the dicusssion of C<EV_ATOMIC_T> in the embedding |
|
|
2297 | section below on what exactly this means). |
|
|
2298 | |
|
|
2299 | This call incurs the overhead of a syscall only once per loop iteration, |
|
|
2300 | so while the overhead might be noticable, it doesn't apply to repeated |
|
|
2301 | calls to C<ev_async_send>. |
|
|
2302 | |
|
|
2303 | =item bool = ev_async_pending (ev_async *) |
|
|
2304 | |
|
|
2305 | Returns a non-zero value when C<ev_async_send> has been called on the |
|
|
2306 | watcher but the event has not yet been processed (or even noted) by the |
|
|
2307 | event loop. |
|
|
2308 | |
|
|
2309 | C<ev_async_send> sets a flag in the watcher and wakes up the loop. When |
|
|
2310 | the loop iterates next and checks for the watcher to have become active, |
|
|
2311 | it will reset the flag again. C<ev_async_pending> can be used to very |
|
|
2312 | quickly check wether invoking the loop might be a good idea. |
|
|
2313 | |
|
|
2314 | Not that this does I<not> check wether the watcher itself is pending, only |
|
|
2315 | wether it has been requested to make this watcher pending. |
1655 | |
2316 | |
1656 | =back |
2317 | =back |
1657 | |
2318 | |
1658 | |
2319 | |
1659 | =head1 OTHER FUNCTIONS |
2320 | =head1 OTHER FUNCTIONS |
… | |
… | |
1731 | |
2392 | |
1732 | =item * Priorities are not currently supported. Initialising priorities |
2393 | =item * Priorities are not currently supported. Initialising priorities |
1733 | will fail and all watchers will have the same priority, even though there |
2394 | will fail and all watchers will have the same priority, even though there |
1734 | is an ev_pri field. |
2395 | is an ev_pri field. |
1735 | |
2396 | |
|
|
2397 | =item * In libevent, the last base created gets the signals, in libev, the |
|
|
2398 | first base created (== the default loop) gets the signals. |
|
|
2399 | |
1736 | =item * Other members are not supported. |
2400 | =item * Other members are not supported. |
1737 | |
2401 | |
1738 | =item * The libev emulation is I<not> ABI compatible to libevent, you need |
2402 | =item * The libev emulation is I<not> ABI compatible to libevent, you need |
1739 | to use the libev header file and library. |
2403 | to use the libev header file and library. |
1740 | |
2404 | |
… | |
… | |
1832 | |
2496 | |
1833 | myclass obj; |
2497 | myclass obj; |
1834 | ev::io iow; |
2498 | ev::io iow; |
1835 | iow.set <myclass, &myclass::io_cb> (&obj); |
2499 | iow.set <myclass, &myclass::io_cb> (&obj); |
1836 | |
2500 | |
1837 | =item w->set (void (*function)(watcher &w, int), void *data = 0) |
2501 | =item w->set<function> (void *data = 0) |
1838 | |
2502 | |
1839 | Also sets a callback, but uses a static method or plain function as |
2503 | Also sets a callback, but uses a static method or plain function as |
1840 | callback. The optional C<data> argument will be stored in the watcher's |
2504 | callback. The optional C<data> argument will be stored in the watcher's |
1841 | C<data> member and is free for you to use. |
2505 | C<data> member and is free for you to use. |
1842 | |
2506 | |
|
|
2507 | The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>. |
|
|
2508 | |
1843 | See the method-C<set> above for more details. |
2509 | See the method-C<set> above for more details. |
|
|
2510 | |
|
|
2511 | Example: |
|
|
2512 | |
|
|
2513 | static void io_cb (ev::io &w, int revents) { } |
|
|
2514 | iow.set <io_cb> (); |
1844 | |
2515 | |
1845 | =item w->set (struct ev_loop *) |
2516 | =item w->set (struct ev_loop *) |
1846 | |
2517 | |
1847 | Associates a different C<struct ev_loop> with this watcher. You can only |
2518 | Associates a different C<struct ev_loop> with this watcher. You can only |
1848 | do this when the watcher is inactive (and not pending either). |
2519 | do this when the watcher is inactive (and not pending either). |
… | |
… | |
1861 | |
2532 | |
1862 | =item w->stop () |
2533 | =item w->stop () |
1863 | |
2534 | |
1864 | Stops the watcher if it is active. Again, no C<loop> argument. |
2535 | Stops the watcher if it is active. Again, no C<loop> argument. |
1865 | |
2536 | |
1866 | =item w->again () C<ev::timer>, C<ev::periodic> only |
2537 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
1867 | |
2538 | |
1868 | For C<ev::timer> and C<ev::periodic>, this invokes the corresponding |
2539 | For C<ev::timer> and C<ev::periodic>, this invokes the corresponding |
1869 | C<ev_TYPE_again> function. |
2540 | C<ev_TYPE_again> function. |
1870 | |
2541 | |
1871 | =item w->sweep () C<ev::embed> only |
2542 | =item w->sweep () (C<ev::embed> only) |
1872 | |
2543 | |
1873 | Invokes C<ev_embed_sweep>. |
2544 | Invokes C<ev_embed_sweep>. |
1874 | |
2545 | |
1875 | =item w->update () C<ev::stat> only |
2546 | =item w->update () (C<ev::stat> only) |
1876 | |
2547 | |
1877 | Invokes C<ev_stat_stat>. |
2548 | Invokes C<ev_stat_stat>. |
1878 | |
2549 | |
1879 | =back |
2550 | =back |
1880 | |
2551 | |
… | |
… | |
1883 | Example: Define a class with an IO and idle watcher, start one of them in |
2554 | Example: Define a class with an IO and idle watcher, start one of them in |
1884 | the constructor. |
2555 | the constructor. |
1885 | |
2556 | |
1886 | class myclass |
2557 | class myclass |
1887 | { |
2558 | { |
1888 | ev_io io; void io_cb (ev::io &w, int revents); |
2559 | ev::io io; void io_cb (ev::io &w, int revents); |
1889 | ev_idle idle void idle_cb (ev::idle &w, int revents); |
2560 | ev:idle idle void idle_cb (ev::idle &w, int revents); |
1890 | |
2561 | |
1891 | myclass (); |
2562 | myclass (int fd) |
1892 | } |
|
|
1893 | |
|
|
1894 | myclass::myclass (int fd) |
|
|
1895 | { |
2563 | { |
1896 | io .set <myclass, &myclass::io_cb > (this); |
2564 | io .set <myclass, &myclass::io_cb > (this); |
1897 | idle.set <myclass, &myclass::idle_cb> (this); |
2565 | idle.set <myclass, &myclass::idle_cb> (this); |
1898 | |
2566 | |
1899 | io.start (fd, ev::READ); |
2567 | io.start (fd, ev::READ); |
|
|
2568 | } |
1900 | } |
2569 | }; |
|
|
2570 | |
|
|
2571 | |
|
|
2572 | =head1 OTHER LANGUAGE BINDINGS |
|
|
2573 | |
|
|
2574 | Libev does not offer other language bindings itself, but bindings for a |
|
|
2575 | numbe rof languages exist in the form of third-party packages. If you know |
|
|
2576 | any interesting language binding in addition to the ones listed here, drop |
|
|
2577 | me a note. |
|
|
2578 | |
|
|
2579 | =over 4 |
|
|
2580 | |
|
|
2581 | =item Perl |
|
|
2582 | |
|
|
2583 | The EV module implements the full libev API and is actually used to test |
|
|
2584 | libev. EV is developed together with libev. Apart from the EV core module, |
|
|
2585 | there are additional modules that implement libev-compatible interfaces |
|
|
2586 | to C<libadns> (C<EV::ADNS>), C<Net::SNMP> (C<Net::SNMP::EV>) and the |
|
|
2587 | C<libglib> event core (C<Glib::EV> and C<EV::Glib>). |
|
|
2588 | |
|
|
2589 | It can be found and installed via CPAN, its homepage is found at |
|
|
2590 | L<http://software.schmorp.de/pkg/EV>. |
|
|
2591 | |
|
|
2592 | =item Ruby |
|
|
2593 | |
|
|
2594 | Tony Arcieri has written a ruby extension that offers access to a subset |
|
|
2595 | of the libev API and adds filehandle abstractions, asynchronous DNS and |
|
|
2596 | more on top of it. It can be found via gem servers. Its homepage is at |
|
|
2597 | L<http://rev.rubyforge.org/>. |
|
|
2598 | |
|
|
2599 | =item D |
|
|
2600 | |
|
|
2601 | Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to |
|
|
2602 | be found at L<http://git.llucax.com.ar/?p=software/ev.d.git;a=summary>. |
|
|
2603 | |
|
|
2604 | =back |
1901 | |
2605 | |
1902 | |
2606 | |
1903 | =head1 MACRO MAGIC |
2607 | =head1 MACRO MAGIC |
1904 | |
2608 | |
1905 | Libev can be compiled with a variety of options, the most fundemantal is |
2609 | Libev can be compiled with a variety of options, the most fundamantal |
1906 | C<EV_MULTIPLICITY>. This option determines whether (most) functions and |
2610 | of which is C<EV_MULTIPLICITY>. This option determines whether (most) |
1907 | callbacks have an initial C<struct ev_loop *> argument. |
2611 | functions and callbacks have an initial C<struct ev_loop *> argument. |
1908 | |
2612 | |
1909 | To make it easier to write programs that cope with either variant, the |
2613 | To make it easier to write programs that cope with either variant, the |
1910 | following macros are defined: |
2614 | following macros are defined: |
1911 | |
2615 | |
1912 | =over 4 |
2616 | =over 4 |
… | |
… | |
1941 | |
2645 | |
1942 | =item C<EV_DEFAULT>, C<EV_DEFAULT_> |
2646 | =item C<EV_DEFAULT>, C<EV_DEFAULT_> |
1943 | |
2647 | |
1944 | Similar to the other two macros, this gives you the value of the default |
2648 | Similar to the other two macros, this gives you the value of the default |
1945 | loop, if multiple loops are supported ("ev loop default"). |
2649 | loop, if multiple loops are supported ("ev loop default"). |
|
|
2650 | |
|
|
2651 | =item C<EV_DEFAULT_UC>, C<EV_DEFAULT_UC_> |
|
|
2652 | |
|
|
2653 | Usage identical to C<EV_DEFAULT> and C<EV_DEFAULT_>, but requires that the |
|
|
2654 | default loop has been initialised (C<UC> == unchecked). Their behaviour |
|
|
2655 | is undefined when the default loop has not been initialised by a previous |
|
|
2656 | execution of C<EV_DEFAULT>, C<EV_DEFAULT_> or C<ev_default_init (...)>. |
|
|
2657 | |
|
|
2658 | It is often prudent to use C<EV_DEFAULT> when initialising the first |
|
|
2659 | watcher in a function but use C<EV_DEFAULT_UC> afterwards. |
1946 | |
2660 | |
1947 | =back |
2661 | =back |
1948 | |
2662 | |
1949 | Example: Declare and initialise a check watcher, utilising the above |
2663 | Example: Declare and initialise a check watcher, utilising the above |
1950 | macros so it will work regardless of whether multiple loops are supported |
2664 | macros so it will work regardless of whether multiple loops are supported |
… | |
… | |
1966 | Libev can (and often is) directly embedded into host |
2680 | Libev can (and often is) directly embedded into host |
1967 | applications. Examples of applications that embed it include the Deliantra |
2681 | applications. Examples of applications that embed it include the Deliantra |
1968 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
2682 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
1969 | and rxvt-unicode. |
2683 | and rxvt-unicode. |
1970 | |
2684 | |
1971 | The goal is to enable you to just copy the neecssary files into your |
2685 | The goal is to enable you to just copy the necessary files into your |
1972 | source directory without having to change even a single line in them, so |
2686 | source directory without having to change even a single line in them, so |
1973 | you can easily upgrade by simply copying (or having a checked-out copy of |
2687 | you can easily upgrade by simply copying (or having a checked-out copy of |
1974 | libev somewhere in your source tree). |
2688 | libev somewhere in your source tree). |
1975 | |
2689 | |
1976 | =head2 FILESETS |
2690 | =head2 FILESETS |
… | |
… | |
2046 | |
2760 | |
2047 | libev.m4 |
2761 | libev.m4 |
2048 | |
2762 | |
2049 | =head2 PREPROCESSOR SYMBOLS/MACROS |
2763 | =head2 PREPROCESSOR SYMBOLS/MACROS |
2050 | |
2764 | |
2051 | Libev can be configured via a variety of preprocessor symbols you have to define |
2765 | Libev can be configured via a variety of preprocessor symbols you have to |
2052 | before including any of its files. The default is not to build for multiplicity |
2766 | define before including any of its files. The default in the absense of |
2053 | and only include the select backend. |
2767 | autoconf is noted for every option. |
2054 | |
2768 | |
2055 | =over 4 |
2769 | =over 4 |
2056 | |
2770 | |
2057 | =item EV_STANDALONE |
2771 | =item EV_STANDALONE |
2058 | |
2772 | |
… | |
… | |
2066 | |
2780 | |
2067 | If defined to be C<1>, libev will try to detect the availability of the |
2781 | If defined to be C<1>, libev will try to detect the availability of the |
2068 | monotonic clock option at both compiletime and runtime. Otherwise no use |
2782 | monotonic clock option at both compiletime and runtime. Otherwise no use |
2069 | of the monotonic clock option will be attempted. If you enable this, you |
2783 | of the monotonic clock option will be attempted. If you enable this, you |
2070 | usually have to link against librt or something similar. Enabling it when |
2784 | usually have to link against librt or something similar. Enabling it when |
2071 | the functionality isn't available is safe, though, althoguh you have |
2785 | the functionality isn't available is safe, though, although you have |
2072 | to make sure you link against any libraries where the C<clock_gettime> |
2786 | to make sure you link against any libraries where the C<clock_gettime> |
2073 | function is hiding in (often F<-lrt>). |
2787 | function is hiding in (often F<-lrt>). |
2074 | |
2788 | |
2075 | =item EV_USE_REALTIME |
2789 | =item EV_USE_REALTIME |
2076 | |
2790 | |
2077 | If defined to be C<1>, libev will try to detect the availability of the |
2791 | If defined to be C<1>, libev will try to detect the availability of the |
2078 | realtime clock option at compiletime (and assume its availability at |
2792 | realtime clock option at compiletime (and assume its availability at |
2079 | runtime if successful). Otherwise no use of the realtime clock option will |
2793 | runtime if successful). Otherwise no use of the realtime clock option will |
2080 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
2794 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
2081 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries |
2795 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See the |
2082 | in the description of C<EV_USE_MONOTONIC>, though. |
2796 | note about libraries in the description of C<EV_USE_MONOTONIC>, though. |
|
|
2797 | |
|
|
2798 | =item EV_USE_NANOSLEEP |
|
|
2799 | |
|
|
2800 | If defined to be C<1>, libev will assume that C<nanosleep ()> is available |
|
|
2801 | and will use it for delays. Otherwise it will use C<select ()>. |
|
|
2802 | |
|
|
2803 | =item EV_USE_EVENTFD |
|
|
2804 | |
|
|
2805 | If defined to be C<1>, then libev will assume that C<eventfd ()> is |
|
|
2806 | available and will probe for kernel support at runtime. This will improve |
|
|
2807 | C<ev_signal> and C<ev_async> performance and reduce resource consumption. |
|
|
2808 | If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc |
|
|
2809 | 2.7 or newer, otherwise disabled. |
2083 | |
2810 | |
2084 | =item EV_USE_SELECT |
2811 | =item EV_USE_SELECT |
2085 | |
2812 | |
2086 | If undefined or defined to be C<1>, libev will compile in support for the |
2813 | If undefined or defined to be C<1>, libev will compile in support for the |
2087 | C<select>(2) backend. No attempt at autodetection will be done: if no |
2814 | C<select>(2) backend. No attempt at autodetection will be done: if no |
… | |
… | |
2106 | be used is the winsock select). This means that it will call |
2833 | be used is the winsock select). This means that it will call |
2107 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
2834 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
2108 | it is assumed that all these functions actually work on fds, even |
2835 | it is assumed that all these functions actually work on fds, even |
2109 | on win32. Should not be defined on non-win32 platforms. |
2836 | on win32. Should not be defined on non-win32 platforms. |
2110 | |
2837 | |
|
|
2838 | =item EV_FD_TO_WIN32_HANDLE |
|
|
2839 | |
|
|
2840 | If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map |
|
|
2841 | file descriptors to socket handles. When not defining this symbol (the |
|
|
2842 | default), then libev will call C<_get_osfhandle>, which is usually |
|
|
2843 | correct. In some cases, programs use their own file descriptor management, |
|
|
2844 | in which case they can provide this function to map fds to socket handles. |
|
|
2845 | |
2111 | =item EV_USE_POLL |
2846 | =item EV_USE_POLL |
2112 | |
2847 | |
2113 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
2848 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
2114 | backend. Otherwise it will be enabled on non-win32 platforms. It |
2849 | backend. Otherwise it will be enabled on non-win32 platforms. It |
2115 | takes precedence over select. |
2850 | takes precedence over select. |
2116 | |
2851 | |
2117 | =item EV_USE_EPOLL |
2852 | =item EV_USE_EPOLL |
2118 | |
2853 | |
2119 | If defined to be C<1>, libev will compile in support for the Linux |
2854 | If defined to be C<1>, libev will compile in support for the Linux |
2120 | C<epoll>(7) backend. Its availability will be detected at runtime, |
2855 | C<epoll>(7) backend. Its availability will be detected at runtime, |
2121 | otherwise another method will be used as fallback. This is the |
2856 | otherwise another method will be used as fallback. This is the preferred |
2122 | preferred backend for GNU/Linux systems. |
2857 | backend for GNU/Linux systems. If undefined, it will be enabled if the |
|
|
2858 | headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
2123 | |
2859 | |
2124 | =item EV_USE_KQUEUE |
2860 | =item EV_USE_KQUEUE |
2125 | |
2861 | |
2126 | If defined to be C<1>, libev will compile in support for the BSD style |
2862 | If defined to be C<1>, libev will compile in support for the BSD style |
2127 | C<kqueue>(2) backend. Its actual availability will be detected at runtime, |
2863 | C<kqueue>(2) backend. Its actual availability will be detected at runtime, |
… | |
… | |
2146 | |
2882 | |
2147 | =item EV_USE_INOTIFY |
2883 | =item EV_USE_INOTIFY |
2148 | |
2884 | |
2149 | If defined to be C<1>, libev will compile in support for the Linux inotify |
2885 | If defined to be C<1>, libev will compile in support for the Linux inotify |
2150 | interface to speed up C<ev_stat> watchers. Its actual availability will |
2886 | interface to speed up C<ev_stat> watchers. Its actual availability will |
2151 | be detected at runtime. |
2887 | be detected at runtime. If undefined, it will be enabled if the headers |
|
|
2888 | indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
|
|
2889 | |
|
|
2890 | =item EV_ATOMIC_T |
|
|
2891 | |
|
|
2892 | Libev requires an integer type (suitable for storing C<0> or C<1>) whose |
|
|
2893 | access is atomic with respect to other threads or signal contexts. No such |
|
|
2894 | type is easily found in the C language, so you can provide your own type |
|
|
2895 | that you know is safe for your purposes. It is used both for signal handler "locking" |
|
|
2896 | as well as for signal and thread safety in C<ev_async> watchers. |
|
|
2897 | |
|
|
2898 | In the absense of this define, libev will use C<sig_atomic_t volatile> |
|
|
2899 | (from F<signal.h>), which is usually good enough on most platforms. |
2152 | |
2900 | |
2153 | =item EV_H |
2901 | =item EV_H |
2154 | |
2902 | |
2155 | The name of the F<ev.h> header file used to include it. The default if |
2903 | The name of the F<ev.h> header file used to include it. The default if |
2156 | undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This |
2904 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
2157 | can be used to virtually rename the F<ev.h> header file in case of conflicts. |
2905 | used to virtually rename the F<ev.h> header file in case of conflicts. |
2158 | |
2906 | |
2159 | =item EV_CONFIG_H |
2907 | =item EV_CONFIG_H |
2160 | |
2908 | |
2161 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
2909 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
2162 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
2910 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
2163 | C<EV_H>, above. |
2911 | C<EV_H>, above. |
2164 | |
2912 | |
2165 | =item EV_EVENT_H |
2913 | =item EV_EVENT_H |
2166 | |
2914 | |
2167 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
2915 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
2168 | of how the F<event.h> header can be found. |
2916 | of how the F<event.h> header can be found, the default is C<"event.h">. |
2169 | |
2917 | |
2170 | =item EV_PROTOTYPES |
2918 | =item EV_PROTOTYPES |
2171 | |
2919 | |
2172 | If defined to be C<0>, then F<ev.h> will not define any function |
2920 | If defined to be C<0>, then F<ev.h> will not define any function |
2173 | prototypes, but still define all the structs and other symbols. This is |
2921 | prototypes, but still define all the structs and other symbols. This is |
… | |
… | |
2224 | =item EV_FORK_ENABLE |
2972 | =item EV_FORK_ENABLE |
2225 | |
2973 | |
2226 | If undefined or defined to be C<1>, then fork watchers are supported. If |
2974 | If undefined or defined to be C<1>, then fork watchers are supported. If |
2227 | defined to be C<0>, then they are not. |
2975 | defined to be C<0>, then they are not. |
2228 | |
2976 | |
|
|
2977 | =item EV_ASYNC_ENABLE |
|
|
2978 | |
|
|
2979 | If undefined or defined to be C<1>, then async watchers are supported. If |
|
|
2980 | defined to be C<0>, then they are not. |
|
|
2981 | |
2229 | =item EV_MINIMAL |
2982 | =item EV_MINIMAL |
2230 | |
2983 | |
2231 | If you need to shave off some kilobytes of code at the expense of some |
2984 | If you need to shave off some kilobytes of code at the expense of some |
2232 | speed, define this symbol to C<1>. Currently only used for gcc to override |
2985 | speed, define this symbol to C<1>. Currently this is used to override some |
2233 | some inlining decisions, saves roughly 30% codesize of amd64. |
2986 | inlining decisions, saves roughly 30% codesize of amd64. It also selects a |
|
|
2987 | much smaller 2-heap for timer management over the default 4-heap. |
2234 | |
2988 | |
2235 | =item EV_PID_HASHSIZE |
2989 | =item EV_PID_HASHSIZE |
2236 | |
2990 | |
2237 | C<ev_child> watchers use a small hash table to distribute workload by |
2991 | C<ev_child> watchers use a small hash table to distribute workload by |
2238 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
2992 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
2239 | than enough. If you need to manage thousands of children you might want to |
2993 | than enough. If you need to manage thousands of children you might want to |
2240 | increase this value (I<must> be a power of two). |
2994 | increase this value (I<must> be a power of two). |
2241 | |
2995 | |
2242 | =item EV_INOTIFY_HASHSIZE |
2996 | =item EV_INOTIFY_HASHSIZE |
2243 | |
2997 | |
2244 | C<ev_staz> watchers use a small hash table to distribute workload by |
2998 | C<ev_stat> watchers use a small hash table to distribute workload by |
2245 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
2999 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
2246 | usually more than enough. If you need to manage thousands of C<ev_stat> |
3000 | usually more than enough. If you need to manage thousands of C<ev_stat> |
2247 | watchers you might want to increase this value (I<must> be a power of |
3001 | watchers you might want to increase this value (I<must> be a power of |
2248 | two). |
3002 | two). |
2249 | |
3003 | |
|
|
3004 | =item EV_USE_4HEAP |
|
|
3005 | |
|
|
3006 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
|
|
3007 | timer and periodics heap, libev uses a 4-heap when this symbol is defined |
|
|
3008 | to C<1>. The 4-heap uses more complicated (longer) code but has a |
|
|
3009 | noticable after performance with many (thousands) of watchers. |
|
|
3010 | |
|
|
3011 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
|
|
3012 | (disabled). |
|
|
3013 | |
|
|
3014 | =item EV_HEAP_CACHE_AT |
|
|
3015 | |
|
|
3016 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
|
|
3017 | timer and periodics heap, libev can cache the timestamp (I<at>) within |
|
|
3018 | the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>), |
|
|
3019 | which uses 8-12 bytes more per watcher and a few hundred bytes more code, |
|
|
3020 | but avoids random read accesses on heap changes. This noticably improves |
|
|
3021 | performance noticably with with many (hundreds) of watchers. |
|
|
3022 | |
|
|
3023 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
|
|
3024 | (disabled). |
|
|
3025 | |
2250 | =item EV_COMMON |
3026 | =item EV_COMMON |
2251 | |
3027 | |
2252 | By default, all watchers have a C<void *data> member. By redefining |
3028 | By default, all watchers have a C<void *data> member. By redefining |
2253 | this macro to a something else you can include more and other types of |
3029 | this macro to a something else you can include more and other types of |
2254 | members. You have to define it each time you include one of the files, |
3030 | members. You have to define it each time you include one of the files, |
… | |
… | |
2266 | |
3042 | |
2267 | =item ev_set_cb (ev, cb) |
3043 | =item ev_set_cb (ev, cb) |
2268 | |
3044 | |
2269 | Can be used to change the callback member declaration in each watcher, |
3045 | Can be used to change the callback member declaration in each watcher, |
2270 | and the way callbacks are invoked and set. Must expand to a struct member |
3046 | and the way callbacks are invoked and set. Must expand to a struct member |
2271 | definition and a statement, respectively. See the F<ev.v> header file for |
3047 | definition and a statement, respectively. See the F<ev.h> header file for |
2272 | their default definitions. One possible use for overriding these is to |
3048 | their default definitions. One possible use for overriding these is to |
2273 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
3049 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
2274 | method calls instead of plain function calls in C++. |
3050 | method calls instead of plain function calls in C++. |
|
|
3051 | |
|
|
3052 | =head2 EXPORTED API SYMBOLS |
|
|
3053 | |
|
|
3054 | If you need to re-export the API (e.g. via a dll) and you need a list of |
|
|
3055 | exported symbols, you can use the provided F<Symbol.*> files which list |
|
|
3056 | all public symbols, one per line: |
|
|
3057 | |
|
|
3058 | Symbols.ev for libev proper |
|
|
3059 | Symbols.event for the libevent emulation |
|
|
3060 | |
|
|
3061 | This can also be used to rename all public symbols to avoid clashes with |
|
|
3062 | multiple versions of libev linked together (which is obviously bad in |
|
|
3063 | itself, but sometimes it is inconvinient to avoid this). |
|
|
3064 | |
|
|
3065 | A sed command like this will create wrapper C<#define>'s that you need to |
|
|
3066 | include before including F<ev.h>: |
|
|
3067 | |
|
|
3068 | <Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h |
|
|
3069 | |
|
|
3070 | This would create a file F<wrap.h> which essentially looks like this: |
|
|
3071 | |
|
|
3072 | #define ev_backend myprefix_ev_backend |
|
|
3073 | #define ev_check_start myprefix_ev_check_start |
|
|
3074 | #define ev_check_stop myprefix_ev_check_stop |
|
|
3075 | ... |
2275 | |
3076 | |
2276 | =head2 EXAMPLES |
3077 | =head2 EXAMPLES |
2277 | |
3078 | |
2278 | For a real-world example of a program the includes libev |
3079 | For a real-world example of a program the includes libev |
2279 | verbatim, you can have a look at the EV perl module |
3080 | verbatim, you can have a look at the EV perl module |
… | |
… | |
2302 | |
3103 | |
2303 | #include "ev_cpp.h" |
3104 | #include "ev_cpp.h" |
2304 | #include "ev.c" |
3105 | #include "ev.c" |
2305 | |
3106 | |
2306 | |
3107 | |
|
|
3108 | =head1 THREADS AND COROUTINES |
|
|
3109 | |
|
|
3110 | =head2 THREADS |
|
|
3111 | |
|
|
3112 | Libev itself is completely threadsafe, but it uses no locking. This |
|
|
3113 | means that you can use as many loops as you want in parallel, as long as |
|
|
3114 | only one thread ever calls into one libev function with the same loop |
|
|
3115 | parameter. |
|
|
3116 | |
|
|
3117 | Or put differently: calls with different loop parameters can be done in |
|
|
3118 | parallel from multiple threads, calls with the same loop parameter must be |
|
|
3119 | done serially (but can be done from different threads, as long as only one |
|
|
3120 | thread ever is inside a call at any point in time, e.g. by using a mutex |
|
|
3121 | per loop). |
|
|
3122 | |
|
|
3123 | If you want to know which design is best for your problem, then I cannot |
|
|
3124 | help you but by giving some generic advice: |
|
|
3125 | |
|
|
3126 | =over 4 |
|
|
3127 | |
|
|
3128 | =item * most applications have a main thread: use the default libev loop |
|
|
3129 | in that thread, or create a seperate thread running only the default loop. |
|
|
3130 | |
|
|
3131 | This helps integrating other libraries or software modules that use libev |
|
|
3132 | themselves and don't care/know about threading. |
|
|
3133 | |
|
|
3134 | =item * one loop per thread is usually a good model. |
|
|
3135 | |
|
|
3136 | Doing this is almost never wrong, sometimes a better-performance model |
|
|
3137 | exists, but it is always a good start. |
|
|
3138 | |
|
|
3139 | =item * other models exist, such as the leader/follower pattern, where one |
|
|
3140 | loop is handed through multiple threads in a kind of round-robbin fashion. |
|
|
3141 | |
|
|
3142 | Chosing a model is hard - look around, learn, know that usually you cna do |
|
|
3143 | better than you currently do :-) |
|
|
3144 | |
|
|
3145 | =item * often you need to talk to some other thread which blocks in the |
|
|
3146 | event loop - C<ev_async> watchers can be used to wake them up from other |
|
|
3147 | threads safely (or from signal contexts...). |
|
|
3148 | |
|
|
3149 | =back |
|
|
3150 | |
|
|
3151 | =head2 COROUTINES |
|
|
3152 | |
|
|
3153 | Libev is much more accomodating to coroutines ("cooperative threads"): |
|
|
3154 | libev fully supports nesting calls to it's functions from different |
|
|
3155 | coroutines (e.g. you can call C<ev_loop> on the same loop from two |
|
|
3156 | different coroutines and switch freely between both coroutines running the |
|
|
3157 | loop, as long as you don't confuse yourself). The only exception is that |
|
|
3158 | you must not do this from C<ev_periodic> reschedule callbacks. |
|
|
3159 | |
|
|
3160 | Care has been invested into making sure that libev does not keep local |
|
|
3161 | state inside C<ev_loop>, and other calls do not usually allow coroutine |
|
|
3162 | switches. |
|
|
3163 | |
|
|
3164 | |
2307 | =head1 COMPLEXITIES |
3165 | =head1 COMPLEXITIES |
2308 | |
3166 | |
2309 | In this section the complexities of (many of) the algorithms used inside |
3167 | In this section the complexities of (many of) the algorithms used inside |
2310 | libev will be explained. For complexity discussions about backends see the |
3168 | libev will be explained. For complexity discussions about backends see the |
2311 | documentation for C<ev_default_init>. |
3169 | documentation for C<ev_default_init>. |
… | |
… | |
2320 | |
3178 | |
2321 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
3179 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2322 | |
3180 | |
2323 | This means that, when you have a watcher that triggers in one hour and |
3181 | This means that, when you have a watcher that triggers in one hour and |
2324 | there are 100 watchers that would trigger before that then inserting will |
3182 | there are 100 watchers that would trigger before that then inserting will |
2325 | have to skip those 100 watchers. |
3183 | have to skip roughly seven (C<ld 100>) of these watchers. |
2326 | |
3184 | |
2327 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
3185 | =item Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers) |
2328 | |
3186 | |
2329 | That means that for changing a timer costs less than removing/adding them |
3187 | That means that changing a timer costs less than removing/adding them |
2330 | as only the relative motion in the event queue has to be paid for. |
3188 | as only the relative motion in the event queue has to be paid for. |
2331 | |
3189 | |
2332 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
3190 | =item Starting io/check/prepare/idle/signal/child/fork/async watchers: O(1) |
2333 | |
3191 | |
2334 | These just add the watcher into an array or at the head of a list. |
3192 | These just add the watcher into an array or at the head of a list. |
|
|
3193 | |
2335 | =item Stopping check/prepare/idle watchers: O(1) |
3194 | =item Stopping check/prepare/idle/fork/async watchers: O(1) |
2336 | |
3195 | |
2337 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
3196 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2338 | |
3197 | |
2339 | These watchers are stored in lists then need to be walked to find the |
3198 | These watchers are stored in lists then need to be walked to find the |
2340 | correct watcher to remove. The lists are usually short (you don't usually |
3199 | correct watcher to remove. The lists are usually short (you don't usually |
2341 | have many watchers waiting for the same fd or signal). |
3200 | have many watchers waiting for the same fd or signal). |
2342 | |
3201 | |
2343 | =item Finding the next timer per loop iteration: O(1) |
3202 | =item Finding the next timer in each loop iteration: O(1) |
|
|
3203 | |
|
|
3204 | By virtue of using a binary or 4-heap, the next timer is always found at a |
|
|
3205 | fixed position in the storage array. |
2344 | |
3206 | |
2345 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
3207 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2346 | |
3208 | |
2347 | A change means an I/O watcher gets started or stopped, which requires |
3209 | A change means an I/O watcher gets started or stopped, which requires |
2348 | libev to recalculate its status (and possibly tell the kernel). |
3210 | libev to recalculate its status (and possibly tell the kernel, depending |
|
|
3211 | on backend and wether C<ev_io_set> was used). |
2349 | |
3212 | |
2350 | =item Activating one watcher: O(1) |
3213 | =item Activating one watcher (putting it into the pending state): O(1) |
2351 | |
3214 | |
2352 | =item Priority handling: O(number_of_priorities) |
3215 | =item Priority handling: O(number_of_priorities) |
2353 | |
3216 | |
2354 | Priorities are implemented by allocating some space for each |
3217 | Priorities are implemented by allocating some space for each |
2355 | priority. When doing priority-based operations, libev usually has to |
3218 | priority. When doing priority-based operations, libev usually has to |
2356 | linearly search all the priorities. |
3219 | linearly search all the priorities, but starting/stopping and activating |
|
|
3220 | watchers becomes O(1) w.r.t. priority handling. |
|
|
3221 | |
|
|
3222 | =item Sending an ev_async: O(1) |
|
|
3223 | |
|
|
3224 | =item Processing ev_async_send: O(number_of_async_watchers) |
|
|
3225 | |
|
|
3226 | =item Processing signals: O(max_signal_number) |
|
|
3227 | |
|
|
3228 | Sending involves a syscall I<iff> there were no other C<ev_async_send> |
|
|
3229 | calls in the current loop iteration. Checking for async and signal events |
|
|
3230 | involves iterating over all running async watchers or all signal numbers. |
2357 | |
3231 | |
2358 | =back |
3232 | =back |
2359 | |
3233 | |
2360 | |
3234 | |
|
|
3235 | =head1 Win32 platform limitations and workarounds |
|
|
3236 | |
|
|
3237 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
|
|
3238 | requires, and its I/O model is fundamentally incompatible with the POSIX |
|
|
3239 | model. Libev still offers limited functionality on this platform in |
|
|
3240 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
|
|
3241 | descriptors. This only applies when using Win32 natively, not when using |
|
|
3242 | e.g. cygwin. |
|
|
3243 | |
|
|
3244 | Lifting these limitations would basically require the full |
|
|
3245 | re-implementation of the I/O system. If you are into these kinds of |
|
|
3246 | things, then note that glib does exactly that for you in a very portable |
|
|
3247 | way (note also that glib is the slowest event library known to man). |
|
|
3248 | |
|
|
3249 | There is no supported compilation method available on windows except |
|
|
3250 | embedding it into other applications. |
|
|
3251 | |
|
|
3252 | Due to the many, low, and arbitrary limits on the win32 platform and |
|
|
3253 | the abysmal performance of winsockets, using a large number of sockets |
|
|
3254 | is not recommended (and not reasonable). If your program needs to use |
|
|
3255 | more than a hundred or so sockets, then likely it needs to use a totally |
|
|
3256 | different implementation for windows, as libev offers the POSIX readyness |
|
|
3257 | notification model, which cannot be implemented efficiently on windows |
|
|
3258 | (microsoft monopoly games). |
|
|
3259 | |
|
|
3260 | =over 4 |
|
|
3261 | |
|
|
3262 | =item The winsocket select function |
|
|
3263 | |
|
|
3264 | The winsocket C<select> function doesn't follow POSIX in that it requires |
|
|
3265 | socket I<handles> and not socket I<file descriptors>. This makes select |
|
|
3266 | very inefficient, and also requires a mapping from file descriptors |
|
|
3267 | to socket handles. See the discussion of the C<EV_SELECT_USE_FD_SET>, |
|
|
3268 | C<EV_SELECT_IS_WINSOCKET> and C<EV_FD_TO_WIN32_HANDLE> preprocessor |
|
|
3269 | symbols for more info. |
|
|
3270 | |
|
|
3271 | The configuration for a "naked" win32 using the microsoft runtime |
|
|
3272 | libraries and raw winsocket select is: |
|
|
3273 | |
|
|
3274 | #define EV_USE_SELECT 1 |
|
|
3275 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
|
|
3276 | |
|
|
3277 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
|
|
3278 | complexity in the O(n²) range when using win32. |
|
|
3279 | |
|
|
3280 | =item Limited number of file descriptors |
|
|
3281 | |
|
|
3282 | Windows has numerous arbitrary (and low) limits on things. |
|
|
3283 | |
|
|
3284 | Early versions of winsocket's select only supported waiting for a maximum |
|
|
3285 | of C<64> handles (probably owning to the fact that all windows kernels |
|
|
3286 | can only wait for C<64> things at the same time internally; microsoft |
|
|
3287 | recommends spawning a chain of threads and wait for 63 handles and the |
|
|
3288 | previous thread in each. Great). |
|
|
3289 | |
|
|
3290 | Newer versions support more handles, but you need to define C<FD_SETSIZE> |
|
|
3291 | to some high number (e.g. C<2048>) before compiling the winsocket select |
|
|
3292 | call (which might be in libev or elsewhere, for example, perl does its own |
|
|
3293 | select emulation on windows). |
|
|
3294 | |
|
|
3295 | Another limit is the number of file descriptors in the microsoft runtime |
|
|
3296 | libraries, which by default is C<64> (there must be a hidden I<64> fetish |
|
|
3297 | or something like this inside microsoft). You can increase this by calling |
|
|
3298 | C<_setmaxstdio>, which can increase this limit to C<2048> (another |
|
|
3299 | arbitrary limit), but is broken in many versions of the microsoft runtime |
|
|
3300 | libraries. |
|
|
3301 | |
|
|
3302 | This might get you to about C<512> or C<2048> sockets (depending on |
|
|
3303 | windows version and/or the phase of the moon). To get more, you need to |
|
|
3304 | wrap all I/O functions and provide your own fd management, but the cost of |
|
|
3305 | calling select (O(n²)) will likely make this unworkable. |
|
|
3306 | |
|
|
3307 | =back |
|
|
3308 | |
|
|
3309 | |
|
|
3310 | =head1 PORTABILITY REQUIREMENTS |
|
|
3311 | |
|
|
3312 | In addition to a working ISO-C implementation, libev relies on a few |
|
|
3313 | additional extensions: |
|
|
3314 | |
|
|
3315 | =over 4 |
|
|
3316 | |
|
|
3317 | =item C<sig_atomic_t volatile> must be thread-atomic as well |
|
|
3318 | |
|
|
3319 | The type C<sig_atomic_t volatile> (or whatever is defined as |
|
|
3320 | C<EV_ATOMIC_T>) must be atomic w.r.t. accesses from different |
|
|
3321 | threads. This is not part of the specification for C<sig_atomic_t>, but is |
|
|
3322 | believed to be sufficiently portable. |
|
|
3323 | |
|
|
3324 | =item C<sigprocmask> must work in a threaded environment |
|
|
3325 | |
|
|
3326 | Libev uses C<sigprocmask> to temporarily block signals. This is not |
|
|
3327 | allowed in a threaded program (C<pthread_sigmask> has to be used). Typical |
|
|
3328 | pthread implementations will either allow C<sigprocmask> in the "main |
|
|
3329 | thread" or will block signals process-wide, both behaviours would |
|
|
3330 | be compatible with libev. Interaction between C<sigprocmask> and |
|
|
3331 | C<pthread_sigmask> could complicate things, however. |
|
|
3332 | |
|
|
3333 | The most portable way to handle signals is to block signals in all threads |
|
|
3334 | except the initial one, and run the default loop in the initial thread as |
|
|
3335 | well. |
|
|
3336 | |
|
|
3337 | =item C<long> must be large enough for common memory allocation sizes |
|
|
3338 | |
|
|
3339 | To improve portability and simplify using libev, libev uses C<long> |
|
|
3340 | internally instead of C<size_t> when allocating its data structures. On |
|
|
3341 | non-POSIX systems (Microsoft...) this might be unexpectedly low, but |
|
|
3342 | is still at least 31 bits everywhere, which is enough for hundreds of |
|
|
3343 | millions of watchers. |
|
|
3344 | |
|
|
3345 | =item C<double> must hold a time value in seconds with enough accuracy |
|
|
3346 | |
|
|
3347 | The type C<double> is used to represent timestamps. It is required to |
|
|
3348 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
|
|
3349 | enough for at least into the year 4000. This requirement is fulfilled by |
|
|
3350 | implementations implementing IEEE 754 (basically all existing ones). |
|
|
3351 | |
|
|
3352 | =back |
|
|
3353 | |
|
|
3354 | If you know of other additional requirements drop me a note. |
|
|
3355 | |
|
|
3356 | |
2361 | =head1 AUTHOR |
3357 | =head1 AUTHOR |
2362 | |
3358 | |
2363 | Marc Lehmann <libev@schmorp.de>. |
3359 | Marc Lehmann <libev@schmorp.de>. |
2364 | |
3360 | |