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8 | |
8 | |
9 | =head2 EXAMPLE PROGRAM |
9 | =head2 EXAMPLE PROGRAM |
10 | |
10 | |
11 | // a single header file is required |
11 | // a single header file is required |
12 | #include <ev.h> |
12 | #include <ev.h> |
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13 | |
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14 | #include <stdio.h> // for puts |
13 | |
15 | |
14 | // every watcher type has its own typedef'd struct |
16 | // every watcher type has its own typedef'd struct |
15 | // with the name ev_TYPE |
17 | // with the name ev_TYPE |
16 | ev_io stdin_watcher; |
18 | ev_io stdin_watcher; |
17 | ev_timer timeout_watcher; |
19 | ev_timer timeout_watcher; |
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24 | puts ("stdin ready"); |
26 | puts ("stdin ready"); |
25 | // for one-shot events, one must manually stop the watcher |
27 | // for one-shot events, one must manually stop the watcher |
26 | // with its corresponding stop function. |
28 | // with its corresponding stop function. |
27 | ev_io_stop (EV_A_ w); |
29 | ev_io_stop (EV_A_ w); |
28 | |
30 | |
29 | // this causes all nested ev_loop's to stop iterating |
31 | // this causes all nested ev_run's to stop iterating |
30 | ev_unloop (EV_A_ EVUNLOOP_ALL); |
32 | ev_break (EV_A_ EVBREAK_ALL); |
31 | } |
33 | } |
32 | |
34 | |
33 | // another callback, this time for a time-out |
35 | // another callback, this time for a time-out |
34 | static void |
36 | static void |
35 | timeout_cb (EV_P_ ev_timer *w, int revents) |
37 | timeout_cb (EV_P_ ev_timer *w, int revents) |
36 | { |
38 | { |
37 | puts ("timeout"); |
39 | puts ("timeout"); |
38 | // this causes the innermost ev_loop to stop iterating |
40 | // this causes the innermost ev_run to stop iterating |
39 | ev_unloop (EV_A_ EVUNLOOP_ONE); |
41 | ev_break (EV_A_ EVBREAK_ONE); |
40 | } |
42 | } |
41 | |
43 | |
42 | int |
44 | int |
43 | main (void) |
45 | main (void) |
44 | { |
46 | { |
45 | // use the default event loop unless you have special needs |
47 | // use the default event loop unless you have special needs |
46 | ev_loop *loop = ev_default_loop (0); |
48 | struct ev_loop *loop = EV_DEFAULT; |
47 | |
49 | |
48 | // initialise an io watcher, then start it |
50 | // initialise an io watcher, then start it |
49 | // this one will watch for stdin to become readable |
51 | // this one will watch for stdin to become readable |
50 | ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
52 | ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
51 | ev_io_start (loop, &stdin_watcher); |
53 | ev_io_start (loop, &stdin_watcher); |
… | |
… | |
54 | // simple non-repeating 5.5 second timeout |
56 | // simple non-repeating 5.5 second timeout |
55 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
57 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
56 | ev_timer_start (loop, &timeout_watcher); |
58 | ev_timer_start (loop, &timeout_watcher); |
57 | |
59 | |
58 | // now wait for events to arrive |
60 | // now wait for events to arrive |
59 | ev_loop (loop, 0); |
61 | ev_run (loop, 0); |
60 | |
62 | |
61 | // unloop was called, so exit |
63 | // unloop was called, so exit |
62 | return 0; |
64 | return 0; |
63 | } |
65 | } |
64 | |
66 | |
65 | =head1 DESCRIPTION |
67 | =head1 ABOUT THIS DOCUMENT |
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68 | |
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69 | This document documents the libev software package. |
66 | |
70 | |
67 | The newest version of this document is also available as an html-formatted |
71 | The newest version of this document is also available as an html-formatted |
68 | web page you might find easier to navigate when reading it for the first |
72 | web page you might find easier to navigate when reading it for the first |
69 | time: L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod>. |
73 | time: L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod>. |
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74 | |
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75 | While this document tries to be as complete as possible in documenting |
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76 | libev, its usage and the rationale behind its design, it is not a tutorial |
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77 | on event-based programming, nor will it introduce event-based programming |
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78 | with libev. |
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79 | |
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80 | Familiarity with event based programming techniques in general is assumed |
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81 | throughout this document. |
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82 | |
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83 | =head1 ABOUT LIBEV |
70 | |
84 | |
71 | Libev is an event loop: you register interest in certain events (such as a |
85 | Libev is an event loop: you register interest in certain events (such as a |
72 | file descriptor being readable or a timeout occurring), and it will manage |
86 | file descriptor being readable or a timeout occurring), and it will manage |
73 | these event sources and provide your program with events. |
87 | these event sources and provide your program with events. |
74 | |
88 | |
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… | |
84 | =head2 FEATURES |
98 | =head2 FEATURES |
85 | |
99 | |
86 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
100 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
87 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
101 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
88 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
102 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
89 | (for C<ev_stat>), relative timers (C<ev_timer>), absolute timers |
103 | (for C<ev_stat>), Linux eventfd/signalfd (for faster and cleaner |
90 | with customised rescheduling (C<ev_periodic>), synchronous signals |
104 | inter-thread wakeup (C<ev_async>)/signal handling (C<ev_signal>)) relative |
91 | (C<ev_signal>), process status change events (C<ev_child>), and event |
105 | timers (C<ev_timer>), absolute timers with customised rescheduling |
92 | watchers dealing with the event loop mechanism itself (C<ev_idle>, |
106 | (C<ev_periodic>), synchronous signals (C<ev_signal>), process status |
93 | C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as |
107 | change events (C<ev_child>), and event watchers dealing with the event |
94 | file watchers (C<ev_stat>) and even limited support for fork events |
108 | loop mechanism itself (C<ev_idle>, C<ev_embed>, C<ev_prepare> and |
95 | (C<ev_fork>). |
109 | C<ev_check> watchers) as well as file watchers (C<ev_stat>) and even |
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110 | limited support for fork events (C<ev_fork>). |
96 | |
111 | |
97 | It also is quite fast (see this |
112 | It also is quite fast (see this |
98 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
113 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
99 | for example). |
114 | for example). |
100 | |
115 | |
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103 | Libev is very configurable. In this manual the default (and most common) |
118 | Libev is very configurable. In this manual the default (and most common) |
104 | configuration will be described, which supports multiple event loops. For |
119 | configuration will be described, which supports multiple event loops. For |
105 | more info about various configuration options please have a look at |
120 | more info about various configuration options please have a look at |
106 | B<EMBED> section in this manual. If libev was configured without support |
121 | B<EMBED> section in this manual. If libev was configured without support |
107 | for multiple event loops, then all functions taking an initial argument of |
122 | for multiple event loops, then all functions taking an initial argument of |
108 | name C<loop> (which is always of type C<ev_loop *>) will not have |
123 | name C<loop> (which is always of type C<struct ev_loop *>) will not have |
109 | this argument. |
124 | this argument. |
110 | |
125 | |
111 | =head2 TIME REPRESENTATION |
126 | =head2 TIME REPRESENTATION |
112 | |
127 | |
113 | Libev represents time as a single floating point number, representing the |
128 | Libev represents time as a single floating point number, representing |
114 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
129 | the (fractional) number of seconds since the (POSIX) epoch (in practice |
115 | the beginning of 1970, details are complicated, don't ask). This type is |
130 | somewhere near the beginning of 1970, details are complicated, don't |
116 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
131 | ask). This type is called C<ev_tstamp>, which is what you should use |
117 | to the C<double> type in C, and when you need to do any calculations on |
132 | too. It usually aliases to the C<double> type in C. When you need to do |
118 | it, you should treat it as some floating point value. Unlike the name |
133 | any calculations on it, you should treat it as some floating point value. |
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134 | |
119 | component C<stamp> might indicate, it is also used for time differences |
135 | Unlike the name component C<stamp> might indicate, it is also used for |
120 | throughout libev. |
136 | time differences (e.g. delays) throughout libev. |
121 | |
137 | |
122 | =head1 ERROR HANDLING |
138 | =head1 ERROR HANDLING |
123 | |
139 | |
124 | Libev knows three classes of errors: operating system errors, usage errors |
140 | Libev knows three classes of errors: operating system errors, usage errors |
125 | and internal errors (bugs). |
141 | and internal errors (bugs). |
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149 | |
165 | |
150 | =item ev_tstamp ev_time () |
166 | =item ev_tstamp ev_time () |
151 | |
167 | |
152 | Returns the current time as libev would use it. Please note that the |
168 | Returns the current time as libev would use it. Please note that the |
153 | C<ev_now> function is usually faster and also often returns the timestamp |
169 | C<ev_now> function is usually faster and also often returns the timestamp |
154 | you actually want to know. |
170 | you actually want to know. Also interesting is the combination of |
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171 | C<ev_update_now> and C<ev_now>. |
155 | |
172 | |
156 | =item ev_sleep (ev_tstamp interval) |
173 | =item ev_sleep (ev_tstamp interval) |
157 | |
174 | |
158 | Sleep for the given interval: The current thread will be blocked until |
175 | Sleep for the given interval: The current thread will be blocked until |
159 | either it is interrupted or the given time interval has passed. Basically |
176 | either it is interrupted or the given time interval has passed. Basically |
… | |
… | |
176 | as this indicates an incompatible change. Minor versions are usually |
193 | as this indicates an incompatible change. Minor versions are usually |
177 | compatible to older versions, so a larger minor version alone is usually |
194 | compatible to older versions, so a larger minor version alone is usually |
178 | not a problem. |
195 | not a problem. |
179 | |
196 | |
180 | Example: Make sure we haven't accidentally been linked against the wrong |
197 | Example: Make sure we haven't accidentally been linked against the wrong |
181 | version. |
198 | version (note, however, that this will not detect other ABI mismatches, |
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199 | such as LFS or reentrancy). |
182 | |
200 | |
183 | assert (("libev version mismatch", |
201 | assert (("libev version mismatch", |
184 | ev_version_major () == EV_VERSION_MAJOR |
202 | ev_version_major () == EV_VERSION_MAJOR |
185 | && ev_version_minor () >= EV_VERSION_MINOR)); |
203 | && ev_version_minor () >= EV_VERSION_MINOR)); |
186 | |
204 | |
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197 | assert (("sorry, no epoll, no sex", |
215 | assert (("sorry, no epoll, no sex", |
198 | ev_supported_backends () & EVBACKEND_EPOLL)); |
216 | ev_supported_backends () & EVBACKEND_EPOLL)); |
199 | |
217 | |
200 | =item unsigned int ev_recommended_backends () |
218 | =item unsigned int ev_recommended_backends () |
201 | |
219 | |
202 | Return the set of all backends compiled into this binary of libev and also |
220 | Return the set of all backends compiled into this binary of libev and |
203 | recommended for this platform. This set is often smaller than the one |
221 | also recommended for this platform, meaning it will work for most file |
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222 | descriptor types. This set is often smaller than the one returned by |
204 | returned by C<ev_supported_backends>, as for example kqueue is broken on |
223 | C<ev_supported_backends>, as for example kqueue is broken on most BSDs |
205 | most BSDs and will not be auto-detected unless you explicitly request it |
224 | and will not be auto-detected unless you explicitly request it (assuming |
206 | (assuming you know what you are doing). This is the set of backends that |
225 | you know what you are doing). This is the set of backends that libev will |
207 | libev will probe for if you specify no backends explicitly. |
226 | probe for if you specify no backends explicitly. |
208 | |
227 | |
209 | =item unsigned int ev_embeddable_backends () |
228 | =item unsigned int ev_embeddable_backends () |
210 | |
229 | |
211 | Returns the set of backends that are embeddable in other event loops. This |
230 | Returns the set of backends that are embeddable in other event loops. This |
212 | is the theoretical, all-platform, value. To find which backends |
231 | value is platform-specific but can include backends not available on the |
213 | might be supported on the current system, you would need to look at |
232 | current system. To find which embeddable backends might be supported on |
214 | C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for |
233 | the current system, you would need to look at C<ev_embeddable_backends () |
215 | recommended ones. |
234 | & ev_supported_backends ()>, likewise for recommended ones. |
216 | |
235 | |
217 | See the description of C<ev_embed> watchers for more info. |
236 | See the description of C<ev_embed> watchers for more info. |
218 | |
237 | |
219 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT] |
238 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT] |
220 | |
239 | |
… | |
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274 | ... |
293 | ... |
275 | ev_set_syserr_cb (fatal_error); |
294 | ev_set_syserr_cb (fatal_error); |
276 | |
295 | |
277 | =back |
296 | =back |
278 | |
297 | |
279 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
298 | =head1 FUNCTIONS CONTROLLING EVENT LOOPS |
280 | |
299 | |
281 | An event loop is described by a C<struct ev_loop *> (the C<struct> |
300 | An event loop is described by a C<struct ev_loop *> (the C<struct> is |
282 | is I<not> optional in this case, as there is also an C<ev_loop> |
301 | I<not> optional in this case unless libev 3 compatibility is disabled, as |
283 | I<function>). |
302 | libev 3 had an C<ev_loop> function colliding with the struct name). |
284 | |
303 | |
285 | The library knows two types of such loops, the I<default> loop, which |
304 | The library knows two types of such loops, the I<default> loop, which |
286 | supports signals and child events, and dynamically created loops which do |
305 | supports signals and child events, and dynamically created event loops |
287 | not. |
306 | which do not. |
288 | |
307 | |
289 | =over 4 |
308 | =over 4 |
290 | |
309 | |
291 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
310 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
292 | |
311 | |
293 | This will initialise the default event loop if it hasn't been initialised |
312 | This returns the "default" event loop object, which is what you should |
294 | yet and return it. If the default loop could not be initialised, returns |
313 | normally use when you just need "the event loop". Event loop objects and |
295 | false. If it already was initialised it simply returns it (and ignores the |
314 | the C<flags> parameter are described in more detail in the entry for |
296 | flags. If that is troubling you, check C<ev_backend ()> afterwards). |
315 | C<ev_loop_new>. |
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316 | |
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317 | If the default loop is already initialised then this function simply |
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318 | returns it (and ignores the flags. If that is troubling you, check |
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319 | C<ev_backend ()> afterwards). Otherwise it will create it with the given |
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320 | flags, which should almost always be C<0>, unless the caller is also the |
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321 | one calling C<ev_run> or otherwise qualifies as "the main program". |
297 | |
322 | |
298 | If you don't know what event loop to use, use the one returned from this |
323 | If you don't know what event loop to use, use the one returned from this |
299 | function. |
324 | function (or via the C<EV_DEFAULT> macro). |
300 | |
325 | |
301 | Note that this function is I<not> thread-safe, so if you want to use it |
326 | Note that this function is I<not> thread-safe, so if you want to use it |
302 | from multiple threads, you have to lock (note also that this is unlikely, |
327 | from multiple threads, you have to employ some kind of mutex (note also |
303 | as loops cannot bes hared easily between threads anyway). |
328 | that this case is unlikely, as loops cannot be shared easily between |
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329 | threads anyway). |
304 | |
330 | |
305 | The default loop is the only loop that can handle C<ev_signal> and |
331 | The default loop is the only loop that can handle C<ev_child> watchers, |
306 | C<ev_child> watchers, and to do this, it always registers a handler |
332 | and to do this, it always registers a handler for C<SIGCHLD>. If this is |
307 | for C<SIGCHLD>. If this is a problem for your application you can either |
333 | a problem for your application you can either create a dynamic loop with |
308 | create a dynamic loop with C<ev_loop_new> that doesn't do that, or you |
334 | C<ev_loop_new> which doesn't do that, or you can simply overwrite the |
309 | can simply overwrite the C<SIGCHLD> signal handler I<after> calling |
335 | C<SIGCHLD> signal handler I<after> calling C<ev_default_init>. |
310 | C<ev_default_init>. |
336 | |
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337 | Example: This is the most typical usage. |
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338 | |
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339 | if (!ev_default_loop (0)) |
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340 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
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341 | |
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342 | Example: Restrict libev to the select and poll backends, and do not allow |
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343 | environment settings to be taken into account: |
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344 | |
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345 | ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
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346 | |
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347 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
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348 | |
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349 | This will create and initialise a new event loop object. If the loop |
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350 | could not be initialised, returns false. |
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351 | |
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352 | Note that this function I<is> thread-safe, and one common way to use |
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353 | libev with threads is indeed to create one loop per thread, and using the |
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354 | default loop in the "main" or "initial" thread. |
311 | |
355 | |
312 | The flags argument can be used to specify special behaviour or specific |
356 | The flags argument can be used to specify special behaviour or specific |
313 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
357 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
314 | |
358 | |
315 | The following flags are supported: |
359 | The following flags are supported: |
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330 | useful to try out specific backends to test their performance, or to work |
374 | useful to try out specific backends to test their performance, or to work |
331 | around bugs. |
375 | around bugs. |
332 | |
376 | |
333 | =item C<EVFLAG_FORKCHECK> |
377 | =item C<EVFLAG_FORKCHECK> |
334 | |
378 | |
335 | Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after |
379 | Instead of calling C<ev_loop_fork> manually after a fork, you can also |
336 | a fork, you can also make libev check for a fork in each iteration by |
380 | make libev check for a fork in each iteration by enabling this flag. |
337 | enabling this flag. |
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338 | |
381 | |
339 | This works by calling C<getpid ()> on every iteration of the loop, |
382 | This works by calling C<getpid ()> on every iteration of the loop, |
340 | and thus this might slow down your event loop if you do a lot of loop |
383 | and thus this might slow down your event loop if you do a lot of loop |
341 | iterations and little real work, but is usually not noticeable (on my |
384 | iterations and little real work, but is usually not noticeable (on my |
342 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence |
385 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence |
… | |
… | |
348 | flag. |
391 | flag. |
349 | |
392 | |
350 | This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS> |
393 | This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS> |
351 | environment variable. |
394 | environment variable. |
352 | |
395 | |
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396 | =item C<EVFLAG_NOINOTIFY> |
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397 | |
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398 | When this flag is specified, then libev will not attempt to use the |
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399 | I<inotify> API for it's C<ev_stat> watchers. Apart from debugging and |
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400 | testing, this flag can be useful to conserve inotify file descriptors, as |
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401 | otherwise each loop using C<ev_stat> watchers consumes one inotify handle. |
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402 | |
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403 | =item C<EVFLAG_SIGNALFD> |
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404 | |
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405 | When this flag is specified, then libev will attempt to use the |
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406 | I<signalfd> API for it's C<ev_signal> (and C<ev_child>) watchers. This API |
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407 | delivers signals synchronously, which makes it both faster and might make |
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408 | it possible to get the queued signal data. It can also simplify signal |
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409 | handling with threads, as long as you properly block signals in your |
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410 | threads that are not interested in handling them. |
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411 | |
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412 | Signalfd will not be used by default as this changes your signal mask, and |
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413 | there are a lot of shoddy libraries and programs (glib's threadpool for |
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414 | example) that can't properly initialise their signal masks. |
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415 | |
353 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
416 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
354 | |
417 | |
355 | This is your standard select(2) backend. Not I<completely> standard, as |
418 | This is your standard select(2) backend. Not I<completely> standard, as |
356 | libev tries to roll its own fd_set with no limits on the number of fds, |
419 | libev tries to roll its own fd_set with no limits on the number of fds, |
357 | but if that fails, expect a fairly low limit on the number of fds when |
420 | but if that fails, expect a fairly low limit on the number of fds when |
… | |
… | |
381 | This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and |
444 | This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and |
382 | C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>. |
445 | C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>. |
383 | |
446 | |
384 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
447 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
385 | |
448 | |
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449 | Use the linux-specific epoll(7) interface (for both pre- and post-2.6.9 |
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450 | kernels). |
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451 | |
386 | For few fds, this backend is a bit little slower than poll and select, |
452 | For few fds, this backend is a bit little slower than poll and select, |
387 | but it scales phenomenally better. While poll and select usually scale |
453 | but it scales phenomenally better. While poll and select usually scale |
388 | like O(total_fds) where n is the total number of fds (or the highest fd), |
454 | like O(total_fds) where n is the total number of fds (or the highest fd), |
389 | epoll scales either O(1) or O(active_fds). The epoll design has a number |
455 | epoll scales either O(1) or O(active_fds). |
390 | of shortcomings, such as silently dropping events in some hard-to-detect |
456 | |
391 | cases and requiring a system call per fd change, no fork support and bad |
457 | The epoll mechanism deserves honorable mention as the most misdesigned |
392 | support for dup. |
458 | of the more advanced event mechanisms: mere annoyances include silently |
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459 | dropping file descriptors, requiring a system call per change per file |
|
|
460 | descriptor (and unnecessary guessing of parameters), problems with dup and |
|
|
461 | so on. The biggest issue is fork races, however - if a program forks then |
|
|
462 | I<both> parent and child process have to recreate the epoll set, which can |
|
|
463 | take considerable time (one syscall per file descriptor) and is of course |
|
|
464 | hard to detect. |
|
|
465 | |
|
|
466 | Epoll is also notoriously buggy - embedding epoll fds I<should> work, but |
|
|
467 | of course I<doesn't>, and epoll just loves to report events for totally |
|
|
468 | I<different> file descriptors (even already closed ones, so one cannot |
|
|
469 | even remove them from the set) than registered in the set (especially |
|
|
470 | on SMP systems). Libev tries to counter these spurious notifications by |
|
|
471 | employing an additional generation counter and comparing that against the |
|
|
472 | events to filter out spurious ones, recreating the set when required. Last |
|
|
473 | not least, it also refuses to work with some file descriptors which work |
|
|
474 | perfectly fine with C<select> (files, many character devices...). |
393 | |
475 | |
394 | While stopping, setting and starting an I/O watcher in the same iteration |
476 | While stopping, setting and starting an I/O watcher in the same iteration |
395 | will result in some caching, there is still a system call per such incident |
477 | will result in some caching, there is still a system call per such |
396 | (because the fd could point to a different file description now), so its |
478 | incident (because the same I<file descriptor> could point to a different |
397 | best to avoid that. Also, C<dup ()>'ed file descriptors might not work |
479 | I<file description> now), so its best to avoid that. Also, C<dup ()>'ed |
398 | very well if you register events for both fds. |
480 | file descriptors might not work very well if you register events for both |
399 | |
481 | file descriptors. |
400 | Please note that epoll sometimes generates spurious notifications, so you |
|
|
401 | need to use non-blocking I/O or other means to avoid blocking when no data |
|
|
402 | (or space) is available. |
|
|
403 | |
482 | |
404 | Best performance from this backend is achieved by not unregistering all |
483 | Best performance from this backend is achieved by not unregistering all |
405 | watchers for a file descriptor until it has been closed, if possible, |
484 | watchers for a file descriptor until it has been closed, if possible, |
406 | i.e. keep at least one watcher active per fd at all times. Stopping and |
485 | i.e. keep at least one watcher active per fd at all times. Stopping and |
407 | starting a watcher (without re-setting it) also usually doesn't cause |
486 | starting a watcher (without re-setting it) also usually doesn't cause |
408 | extra overhead. |
487 | extra overhead. A fork can both result in spurious notifications as well |
|
|
488 | as in libev having to destroy and recreate the epoll object, which can |
|
|
489 | take considerable time and thus should be avoided. |
|
|
490 | |
|
|
491 | All this means that, in practice, C<EVBACKEND_SELECT> can be as fast or |
|
|
492 | faster than epoll for maybe up to a hundred file descriptors, depending on |
|
|
493 | the usage. So sad. |
409 | |
494 | |
410 | While nominally embeddable in other event loops, this feature is broken in |
495 | While nominally embeddable in other event loops, this feature is broken in |
411 | all kernel versions tested so far. |
496 | all kernel versions tested so far. |
412 | |
497 | |
413 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
498 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
414 | C<EVBACKEND_POLL>. |
499 | C<EVBACKEND_POLL>. |
415 | |
500 | |
416 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
501 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
417 | |
502 | |
418 | Kqueue deserves special mention, as at the time of this writing, it was |
503 | Kqueue deserves special mention, as at the time of this writing, it |
419 | broken on all BSDs except NetBSD (usually it doesn't work reliably with |
504 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
420 | anything but sockets and pipes, except on Darwin, where of course it's |
505 | with anything but sockets and pipes, except on Darwin, where of course |
421 | completely useless). For this reason it's not being "auto-detected" unless |
506 | it's completely useless). Unlike epoll, however, whose brokenness |
422 | you explicitly specify it in the flags (i.e. using C<EVBACKEND_KQUEUE>) or |
507 | is by design, these kqueue bugs can (and eventually will) be fixed |
423 | libev was compiled on a known-to-be-good (-enough) system like NetBSD. |
508 | without API changes to existing programs. For this reason it's not being |
|
|
509 | "auto-detected" unless you explicitly specify it in the flags (i.e. using |
|
|
510 | C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough) |
|
|
511 | system like NetBSD. |
424 | |
512 | |
425 | You still can embed kqueue into a normal poll or select backend and use it |
513 | You still can embed kqueue into a normal poll or select backend and use it |
426 | only for sockets (after having made sure that sockets work with kqueue on |
514 | only for sockets (after having made sure that sockets work with kqueue on |
427 | the target platform). See C<ev_embed> watchers for more info. |
515 | the target platform). See C<ev_embed> watchers for more info. |
428 | |
516 | |
429 | It scales in the same way as the epoll backend, but the interface to the |
517 | It scales in the same way as the epoll backend, but the interface to the |
430 | kernel is more efficient (which says nothing about its actual speed, of |
518 | kernel is more efficient (which says nothing about its actual speed, of |
431 | course). While stopping, setting and starting an I/O watcher does never |
519 | course). While stopping, setting and starting an I/O watcher does never |
432 | cause an extra system call as with C<EVBACKEND_EPOLL>, it still adds up to |
520 | cause an extra system call as with C<EVBACKEND_EPOLL>, it still adds up to |
433 | two event changes per incident. Support for C<fork ()> is very bad and it |
521 | two event changes per incident. Support for C<fork ()> is very bad (but |
434 | drops fds silently in similarly hard-to-detect cases. |
522 | sane, unlike epoll) and it drops fds silently in similarly hard-to-detect |
|
|
523 | cases |
435 | |
524 | |
436 | This backend usually performs well under most conditions. |
525 | This backend usually performs well under most conditions. |
437 | |
526 | |
438 | While nominally embeddable in other event loops, this doesn't work |
527 | While nominally embeddable in other event loops, this doesn't work |
439 | everywhere, so you might need to test for this. And since it is broken |
528 | everywhere, so you might need to test for this. And since it is broken |
440 | almost everywhere, you should only use it when you have a lot of sockets |
529 | almost everywhere, you should only use it when you have a lot of sockets |
441 | (for which it usually works), by embedding it into another event loop |
530 | (for which it usually works), by embedding it into another event loop |
442 | (e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>) and, did I mention it, |
531 | (e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> (but C<poll> is of course |
443 | using it only for sockets. |
532 | also broken on OS X)) and, did I mention it, using it only for sockets. |
444 | |
533 | |
445 | This backend maps C<EV_READ> into an C<EVFILT_READ> kevent with |
534 | This backend maps C<EV_READ> into an C<EVFILT_READ> kevent with |
446 | C<NOTE_EOF>, and C<EV_WRITE> into an C<EVFILT_WRITE> kevent with |
535 | C<NOTE_EOF>, and C<EV_WRITE> into an C<EVFILT_WRITE> kevent with |
447 | C<NOTE_EOF>. |
536 | C<NOTE_EOF>. |
448 | |
537 | |
… | |
… | |
468 | might perform better. |
557 | might perform better. |
469 | |
558 | |
470 | On the positive side, with the exception of the spurious readiness |
559 | On the positive side, with the exception of the spurious readiness |
471 | notifications, this backend actually performed fully to specification |
560 | notifications, this backend actually performed fully to specification |
472 | in all tests and is fully embeddable, which is a rare feat among the |
561 | in all tests and is fully embeddable, which is a rare feat among the |
473 | OS-specific backends. |
562 | OS-specific backends (I vastly prefer correctness over speed hacks). |
474 | |
563 | |
475 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
564 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
476 | C<EVBACKEND_POLL>. |
565 | C<EVBACKEND_POLL>. |
477 | |
566 | |
478 | =item C<EVBACKEND_ALL> |
567 | =item C<EVBACKEND_ALL> |
… | |
… | |
483 | |
572 | |
484 | It is definitely not recommended to use this flag. |
573 | It is definitely not recommended to use this flag. |
485 | |
574 | |
486 | =back |
575 | =back |
487 | |
576 | |
488 | If one or more of these are or'ed into the flags value, then only these |
577 | If one or more of the backend flags are or'ed into the flags value, |
489 | backends will be tried (in the reverse order as listed here). If none are |
578 | then only these backends will be tried (in the reverse order as listed |
490 | specified, all backends in C<ev_recommended_backends ()> will be tried. |
579 | here). If none are specified, all backends in C<ev_recommended_backends |
491 | |
580 | ()> will be tried. |
492 | Example: This is the most typical usage. |
|
|
493 | |
|
|
494 | if (!ev_default_loop (0)) |
|
|
495 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
|
|
496 | |
|
|
497 | Example: Restrict libev to the select and poll backends, and do not allow |
|
|
498 | environment settings to be taken into account: |
|
|
499 | |
|
|
500 | ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
|
|
501 | |
|
|
502 | Example: Use whatever libev has to offer, but make sure that kqueue is |
|
|
503 | used if available (warning, breaks stuff, best use only with your own |
|
|
504 | private event loop and only if you know the OS supports your types of |
|
|
505 | fds): |
|
|
506 | |
|
|
507 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
|
508 | |
|
|
509 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
|
|
510 | |
|
|
511 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
|
|
512 | always distinct from the default loop. Unlike the default loop, it cannot |
|
|
513 | handle signal and child watchers, and attempts to do so will be greeted by |
|
|
514 | undefined behaviour (or a failed assertion if assertions are enabled). |
|
|
515 | |
|
|
516 | Note that this function I<is> thread-safe, and the recommended way to use |
|
|
517 | libev with threads is indeed to create one loop per thread, and using the |
|
|
518 | default loop in the "main" or "initial" thread. |
|
|
519 | |
581 | |
520 | Example: Try to create a event loop that uses epoll and nothing else. |
582 | Example: Try to create a event loop that uses epoll and nothing else. |
521 | |
583 | |
522 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
584 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
523 | if (!epoller) |
585 | if (!epoller) |
524 | fatal ("no epoll found here, maybe it hides under your chair"); |
586 | fatal ("no epoll found here, maybe it hides under your chair"); |
525 | |
587 | |
|
|
588 | Example: Use whatever libev has to offer, but make sure that kqueue is |
|
|
589 | used if available. |
|
|
590 | |
|
|
591 | struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
|
592 | |
526 | =item ev_default_destroy () |
593 | =item ev_loop_destroy (loop) |
527 | |
594 | |
528 | Destroys the default loop again (frees all memory and kernel state |
595 | Destroys an event loop object (frees all memory and kernel state |
529 | etc.). None of the active event watchers will be stopped in the normal |
596 | etc.). None of the active event watchers will be stopped in the normal |
530 | sense, so e.g. C<ev_is_active> might still return true. It is your |
597 | sense, so e.g. C<ev_is_active> might still return true. It is your |
531 | responsibility to either stop all watchers cleanly yourself I<before> |
598 | responsibility to either stop all watchers cleanly yourself I<before> |
532 | calling this function, or cope with the fact afterwards (which is usually |
599 | calling this function, or cope with the fact afterwards (which is usually |
533 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
600 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
… | |
… | |
535 | |
602 | |
536 | Note that certain global state, such as signal state (and installed signal |
603 | Note that certain global state, such as signal state (and installed signal |
537 | handlers), will not be freed by this function, and related watchers (such |
604 | handlers), will not be freed by this function, and related watchers (such |
538 | as signal and child watchers) would need to be stopped manually. |
605 | as signal and child watchers) would need to be stopped manually. |
539 | |
606 | |
540 | In general it is not advisable to call this function except in the |
607 | This function is normally used on loop objects allocated by |
541 | rare occasion where you really need to free e.g. the signal handling |
608 | C<ev_loop_new>, but it can also be used on the default loop returned by |
|
|
609 | C<ev_default_loop>, in which case it is not thread-safe. |
|
|
610 | |
|
|
611 | Note that it is not advisable to call this function on the default loop |
|
|
612 | except in the rare occasion where you really need to free it's resources. |
542 | pipe fds. If you need dynamically allocated loops it is better to use |
613 | If you need dynamically allocated loops it is better to use C<ev_loop_new> |
543 | C<ev_loop_new> and C<ev_loop_destroy>). |
614 | and C<ev_loop_destroy>. |
544 | |
615 | |
545 | =item ev_loop_destroy (loop) |
616 | =item ev_loop_fork (loop) |
546 | |
617 | |
547 | Like C<ev_default_destroy>, but destroys an event loop created by an |
|
|
548 | earlier call to C<ev_loop_new>. |
|
|
549 | |
|
|
550 | =item ev_default_fork () |
|
|
551 | |
|
|
552 | This function sets a flag that causes subsequent C<ev_loop> iterations |
618 | This function sets a flag that causes subsequent C<ev_run> iterations to |
553 | to reinitialise the kernel state for backends that have one. Despite the |
619 | reinitialise the kernel state for backends that have one. Despite the |
554 | name, you can call it anytime, but it makes most sense after forking, in |
620 | name, you can call it anytime, but it makes most sense after forking, in |
555 | the child process (or both child and parent, but that again makes little |
621 | the child process. You I<must> call it (or use C<EVFLAG_FORKCHECK>) in the |
556 | sense). You I<must> call it in the child before using any of the libev |
622 | child before resuming or calling C<ev_run>. |
557 | functions, and it will only take effect at the next C<ev_loop> iteration. |
623 | |
|
|
624 | Again, you I<have> to call it on I<any> loop that you want to re-use after |
|
|
625 | a fork, I<even if you do not plan to use the loop in the parent>. This is |
|
|
626 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
|
|
627 | during fork. |
558 | |
628 | |
559 | On the other hand, you only need to call this function in the child |
629 | On the other hand, you only need to call this function in the child |
560 | process if and only if you want to use the event library in the child. If |
630 | process if and only if you want to use the event loop in the child. If |
561 | you just fork+exec, you don't have to call it at all. |
631 | you just fork+exec or create a new loop in the child, you don't have to |
|
|
632 | call it at all (in fact, C<epoll> is so badly broken that it makes a |
|
|
633 | difference, but libev will usually detect this case on its own and do a |
|
|
634 | costly reset of the backend). |
562 | |
635 | |
563 | The function itself is quite fast and it's usually not a problem to call |
636 | The function itself is quite fast and it's usually not a problem to call |
564 | it just in case after a fork. To make this easy, the function will fit in |
637 | it just in case after a fork. |
565 | quite nicely into a call to C<pthread_atfork>: |
|
|
566 | |
638 | |
|
|
639 | Example: Automate calling C<ev_loop_fork> on the default loop when |
|
|
640 | using pthreads. |
|
|
641 | |
|
|
642 | static void |
|
|
643 | post_fork_child (void) |
|
|
644 | { |
|
|
645 | ev_loop_fork (EV_DEFAULT); |
|
|
646 | } |
|
|
647 | |
|
|
648 | ... |
567 | pthread_atfork (0, 0, ev_default_fork); |
649 | pthread_atfork (0, 0, post_fork_child); |
568 | |
|
|
569 | =item ev_loop_fork (loop) |
|
|
570 | |
|
|
571 | Like C<ev_default_fork>, but acts on an event loop created by |
|
|
572 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
|
|
573 | after fork that you want to re-use in the child, and how you do this is |
|
|
574 | entirely your own problem. |
|
|
575 | |
650 | |
576 | =item int ev_is_default_loop (loop) |
651 | =item int ev_is_default_loop (loop) |
577 | |
652 | |
578 | Returns true when the given loop is, in fact, the default loop, and false |
653 | Returns true when the given loop is, in fact, the default loop, and false |
579 | otherwise. |
654 | otherwise. |
580 | |
655 | |
581 | =item unsigned int ev_loop_count (loop) |
656 | =item unsigned int ev_iteration (loop) |
582 | |
657 | |
583 | Returns the count of loop iterations for the loop, which is identical to |
658 | Returns the current iteration count for the event loop, which is identical |
584 | the number of times libev did poll for new events. It starts at C<0> and |
659 | to the number of times libev did poll for new events. It starts at C<0> |
585 | happily wraps around with enough iterations. |
660 | and happily wraps around with enough iterations. |
586 | |
661 | |
587 | This value can sometimes be useful as a generation counter of sorts (it |
662 | This value can sometimes be useful as a generation counter of sorts (it |
588 | "ticks" the number of loop iterations), as it roughly corresponds with |
663 | "ticks" the number of loop iterations), as it roughly corresponds with |
589 | C<ev_prepare> and C<ev_check> calls. |
664 | C<ev_prepare> and C<ev_check> calls - and is incremented between the |
|
|
665 | prepare and check phases. |
|
|
666 | |
|
|
667 | =item unsigned int ev_depth (loop) |
|
|
668 | |
|
|
669 | Returns the number of times C<ev_run> was entered minus the number of |
|
|
670 | times C<ev_run> was exited, in other words, the recursion depth. |
|
|
671 | |
|
|
672 | Outside C<ev_run>, this number is zero. In a callback, this number is |
|
|
673 | C<1>, unless C<ev_run> was invoked recursively (or from another thread), |
|
|
674 | in which case it is higher. |
|
|
675 | |
|
|
676 | Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread |
|
|
677 | etc.), doesn't count as "exit" - consider this as a hint to avoid such |
|
|
678 | ungentleman-like behaviour unless it's really convenient. |
590 | |
679 | |
591 | =item unsigned int ev_backend (loop) |
680 | =item unsigned int ev_backend (loop) |
592 | |
681 | |
593 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
682 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
594 | use. |
683 | use. |
… | |
… | |
603 | |
692 | |
604 | =item ev_now_update (loop) |
693 | =item ev_now_update (loop) |
605 | |
694 | |
606 | Establishes the current time by querying the kernel, updating the time |
695 | Establishes the current time by querying the kernel, updating the time |
607 | returned by C<ev_now ()> in the progress. This is a costly operation and |
696 | returned by C<ev_now ()> in the progress. This is a costly operation and |
608 | is usually done automatically within C<ev_loop ()>. |
697 | is usually done automatically within C<ev_run ()>. |
609 | |
698 | |
610 | This function is rarely useful, but when some event callback runs for a |
699 | This function is rarely useful, but when some event callback runs for a |
611 | very long time without entering the event loop, updating libev's idea of |
700 | very long time without entering the event loop, updating libev's idea of |
612 | the current time is a good idea. |
701 | the current time is a good idea. |
613 | |
702 | |
614 | See also "The special problem of time updates" in the C<ev_timer> section. |
703 | See also L<The special problem of time updates> in the C<ev_timer> section. |
615 | |
704 | |
|
|
705 | =item ev_suspend (loop) |
|
|
706 | |
|
|
707 | =item ev_resume (loop) |
|
|
708 | |
|
|
709 | These two functions suspend and resume an event loop, for use when the |
|
|
710 | loop is not used for a while and timeouts should not be processed. |
|
|
711 | |
|
|
712 | A typical use case would be an interactive program such as a game: When |
|
|
713 | the user presses C<^Z> to suspend the game and resumes it an hour later it |
|
|
714 | would be best to handle timeouts as if no time had actually passed while |
|
|
715 | the program was suspended. This can be achieved by calling C<ev_suspend> |
|
|
716 | in your C<SIGTSTP> handler, sending yourself a C<SIGSTOP> and calling |
|
|
717 | C<ev_resume> directly afterwards to resume timer processing. |
|
|
718 | |
|
|
719 | Effectively, all C<ev_timer> watchers will be delayed by the time spend |
|
|
720 | between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers |
|
|
721 | will be rescheduled (that is, they will lose any events that would have |
|
|
722 | occurred while suspended). |
|
|
723 | |
|
|
724 | After calling C<ev_suspend> you B<must not> call I<any> function on the |
|
|
725 | given loop other than C<ev_resume>, and you B<must not> call C<ev_resume> |
|
|
726 | without a previous call to C<ev_suspend>. |
|
|
727 | |
|
|
728 | Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the |
|
|
729 | event loop time (see C<ev_now_update>). |
|
|
730 | |
616 | =item ev_loop (loop, int flags) |
731 | =item ev_run (loop, int flags) |
617 | |
732 | |
618 | Finally, this is it, the event handler. This function usually is called |
733 | Finally, this is it, the event handler. This function usually is called |
619 | after you initialised all your watchers and you want to start handling |
734 | after you have initialised all your watchers and you want to start |
620 | events. |
735 | handling events. It will ask the operating system for any new events, call |
|
|
736 | the watcher callbacks, an then repeat the whole process indefinitely: This |
|
|
737 | is why event loops are called I<loops>. |
621 | |
738 | |
622 | If the flags argument is specified as C<0>, it will not return until |
739 | If the flags argument is specified as C<0>, it will keep handling events |
623 | either no event watchers are active anymore or C<ev_unloop> was called. |
740 | until either no event watchers are active anymore or C<ev_break> was |
|
|
741 | called. |
624 | |
742 | |
625 | Please note that an explicit C<ev_unloop> is usually better than |
743 | Please note that an explicit C<ev_break> is usually better than |
626 | relying on all watchers to be stopped when deciding when a program has |
744 | relying on all watchers to be stopped when deciding when a program has |
627 | finished (especially in interactive programs), but having a program |
745 | finished (especially in interactive programs), but having a program |
628 | that automatically loops as long as it has to and no longer by virtue |
746 | that automatically loops as long as it has to and no longer by virtue |
629 | of relying on its watchers stopping correctly, that is truly a thing of |
747 | of relying on its watchers stopping correctly, that is truly a thing of |
630 | beauty. |
748 | beauty. |
631 | |
749 | |
632 | A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle |
750 | A flags value of C<EVRUN_NOWAIT> will look for new events, will handle |
633 | those events and any already outstanding ones, but will not block your |
751 | those events and any already outstanding ones, but will not wait and |
634 | process in case there are no events and will return after one iteration of |
752 | block your process in case there are no events and will return after one |
635 | the loop. |
753 | iteration of the loop. This is sometimes useful to poll and handle new |
|
|
754 | events while doing lengthy calculations, to keep the program responsive. |
636 | |
755 | |
637 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
756 | A flags value of C<EVRUN_ONCE> will look for new events (waiting if |
638 | necessary) and will handle those and any already outstanding ones. It |
757 | necessary) and will handle those and any already outstanding ones. It |
639 | will block your process until at least one new event arrives (which could |
758 | will block your process until at least one new event arrives (which could |
640 | be an event internal to libev itself, so there is no guarentee that a |
759 | be an event internal to libev itself, so there is no guarantee that a |
641 | user-registered callback will be called), and will return after one |
760 | user-registered callback will be called), and will return after one |
642 | iteration of the loop. |
761 | iteration of the loop. |
643 | |
762 | |
644 | This is useful if you are waiting for some external event in conjunction |
763 | This is useful if you are waiting for some external event in conjunction |
645 | with something not expressible using other libev watchers (i.e. "roll your |
764 | with something not expressible using other libev watchers (i.e. "roll your |
646 | own C<ev_loop>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is |
765 | own C<ev_run>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is |
647 | usually a better approach for this kind of thing. |
766 | usually a better approach for this kind of thing. |
648 | |
767 | |
649 | Here are the gory details of what C<ev_loop> does: |
768 | Here are the gory details of what C<ev_run> does: |
650 | |
769 | |
|
|
770 | - Increment loop depth. |
|
|
771 | - Reset the ev_break status. |
651 | - Before the first iteration, call any pending watchers. |
772 | - Before the first iteration, call any pending watchers. |
|
|
773 | LOOP: |
652 | * If EVFLAG_FORKCHECK was used, check for a fork. |
774 | - If EVFLAG_FORKCHECK was used, check for a fork. |
653 | - If a fork was detected (by any means), queue and call all fork watchers. |
775 | - If a fork was detected (by any means), queue and call all fork watchers. |
654 | - Queue and call all prepare watchers. |
776 | - Queue and call all prepare watchers. |
|
|
777 | - If ev_break was called, goto FINISH. |
655 | - If we have been forked, detach and recreate the kernel state |
778 | - If we have been forked, detach and recreate the kernel state |
656 | as to not disturb the other process. |
779 | as to not disturb the other process. |
657 | - Update the kernel state with all outstanding changes. |
780 | - Update the kernel state with all outstanding changes. |
658 | - Update the "event loop time" (ev_now ()). |
781 | - Update the "event loop time" (ev_now ()). |
659 | - Calculate for how long to sleep or block, if at all |
782 | - Calculate for how long to sleep or block, if at all |
660 | (active idle watchers, EVLOOP_NONBLOCK or not having |
783 | (active idle watchers, EVRUN_NOWAIT or not having |
661 | any active watchers at all will result in not sleeping). |
784 | any active watchers at all will result in not sleeping). |
662 | - Sleep if the I/O and timer collect interval say so. |
785 | - Sleep if the I/O and timer collect interval say so. |
|
|
786 | - Increment loop iteration counter. |
663 | - Block the process, waiting for any events. |
787 | - Block the process, waiting for any events. |
664 | - Queue all outstanding I/O (fd) events. |
788 | - Queue all outstanding I/O (fd) events. |
665 | - Update the "event loop time" (ev_now ()), and do time jump adjustments. |
789 | - Update the "event loop time" (ev_now ()), and do time jump adjustments. |
666 | - Queue all expired timers. |
790 | - Queue all expired timers. |
667 | - Queue all expired periodics. |
791 | - Queue all expired periodics. |
668 | - Unless any events are pending now, queue all idle watchers. |
792 | - Queue all idle watchers with priority higher than that of pending events. |
669 | - Queue all check watchers. |
793 | - Queue all check watchers. |
670 | - Call all queued watchers in reverse order (i.e. check watchers first). |
794 | - Call all queued watchers in reverse order (i.e. check watchers first). |
671 | Signals and child watchers are implemented as I/O watchers, and will |
795 | Signals and child watchers are implemented as I/O watchers, and will |
672 | be handled here by queueing them when their watcher gets executed. |
796 | be handled here by queueing them when their watcher gets executed. |
673 | - If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
797 | - If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT |
674 | were used, or there are no active watchers, return, otherwise |
798 | were used, or there are no active watchers, goto FINISH, otherwise |
675 | continue with step *. |
799 | continue with step LOOP. |
|
|
800 | FINISH: |
|
|
801 | - Reset the ev_break status iff it was EVBREAK_ONE. |
|
|
802 | - Decrement the loop depth. |
|
|
803 | - Return. |
676 | |
804 | |
677 | Example: Queue some jobs and then loop until no events are outstanding |
805 | Example: Queue some jobs and then loop until no events are outstanding |
678 | anymore. |
806 | anymore. |
679 | |
807 | |
680 | ... queue jobs here, make sure they register event watchers as long |
808 | ... queue jobs here, make sure they register event watchers as long |
681 | ... as they still have work to do (even an idle watcher will do..) |
809 | ... as they still have work to do (even an idle watcher will do..) |
682 | ev_loop (my_loop, 0); |
810 | ev_run (my_loop, 0); |
683 | ... jobs done or somebody called unloop. yeah! |
811 | ... jobs done or somebody called unloop. yeah! |
684 | |
812 | |
685 | =item ev_unloop (loop, how) |
813 | =item ev_break (loop, how) |
686 | |
814 | |
687 | Can be used to make a call to C<ev_loop> return early (but only after it |
815 | Can be used to make a call to C<ev_run> return early (but only after it |
688 | has processed all outstanding events). The C<how> argument must be either |
816 | has processed all outstanding events). The C<how> argument must be either |
689 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
817 | C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or |
690 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
818 | C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return. |
691 | |
819 | |
692 | This "unloop state" will be cleared when entering C<ev_loop> again. |
820 | This "unloop state" will be cleared when entering C<ev_run> again. |
693 | |
821 | |
694 | It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls. |
822 | It is safe to call C<ev_break> from outside any C<ev_run> calls. ##TODO## |
695 | |
823 | |
696 | =item ev_ref (loop) |
824 | =item ev_ref (loop) |
697 | |
825 | |
698 | =item ev_unref (loop) |
826 | =item ev_unref (loop) |
699 | |
827 | |
700 | Ref/unref can be used to add or remove a reference count on the event |
828 | Ref/unref can be used to add or remove a reference count on the event |
701 | loop: Every watcher keeps one reference, and as long as the reference |
829 | loop: Every watcher keeps one reference, and as long as the reference |
702 | count is nonzero, C<ev_loop> will not return on its own. |
830 | count is nonzero, C<ev_run> will not return on its own. |
703 | |
831 | |
704 | If you have a watcher you never unregister that should not keep C<ev_loop> |
832 | This is useful when you have a watcher that you never intend to |
705 | from returning, call ev_unref() after starting, and ev_ref() before |
833 | unregister, but that nevertheless should not keep C<ev_run> from |
|
|
834 | returning. In such a case, call C<ev_unref> after starting, and C<ev_ref> |
706 | stopping it. |
835 | before stopping it. |
707 | |
836 | |
708 | As an example, libev itself uses this for its internal signal pipe: It is |
837 | As an example, libev itself uses this for its internal signal pipe: It |
709 | not visible to the libev user and should not keep C<ev_loop> from exiting |
838 | is not visible to the libev user and should not keep C<ev_run> from |
710 | if no event watchers registered by it are active. It is also an excellent |
839 | exiting if no event watchers registered by it are active. It is also an |
711 | way to do this for generic recurring timers or from within third-party |
840 | excellent way to do this for generic recurring timers or from within |
712 | libraries. Just remember to I<unref after start> and I<ref before stop> |
841 | third-party libraries. Just remember to I<unref after start> and I<ref |
713 | (but only if the watcher wasn't active before, or was active before, |
842 | before stop> (but only if the watcher wasn't active before, or was active |
714 | respectively). |
843 | before, respectively. Note also that libev might stop watchers itself |
|
|
844 | (e.g. non-repeating timers) in which case you have to C<ev_ref> |
|
|
845 | in the callback). |
715 | |
846 | |
716 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
847 | Example: Create a signal watcher, but keep it from keeping C<ev_run> |
717 | running when nothing else is active. |
848 | running when nothing else is active. |
718 | |
849 | |
719 | ev_signal exitsig; |
850 | ev_signal exitsig; |
720 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
851 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
721 | ev_signal_start (loop, &exitsig); |
852 | ev_signal_start (loop, &exitsig); |
… | |
… | |
748 | |
879 | |
749 | By setting a higher I<io collect interval> you allow libev to spend more |
880 | By setting a higher I<io collect interval> you allow libev to spend more |
750 | time collecting I/O events, so you can handle more events per iteration, |
881 | time collecting I/O events, so you can handle more events per iteration, |
751 | at the cost of increasing latency. Timeouts (both C<ev_periodic> and |
882 | at the cost of increasing latency. Timeouts (both C<ev_periodic> and |
752 | C<ev_timer>) will be not affected. Setting this to a non-null value will |
883 | C<ev_timer>) will be not affected. Setting this to a non-null value will |
753 | introduce an additional C<ev_sleep ()> call into most loop iterations. |
884 | introduce an additional C<ev_sleep ()> call into most loop iterations. The |
|
|
885 | sleep time ensures that libev will not poll for I/O events more often then |
|
|
886 | once per this interval, on average. |
754 | |
887 | |
755 | Likewise, by setting a higher I<timeout collect interval> you allow libev |
888 | Likewise, by setting a higher I<timeout collect interval> you allow libev |
756 | to spend more time collecting timeouts, at the expense of increased |
889 | to spend more time collecting timeouts, at the expense of increased |
757 | latency/jitter/inexactness (the watcher callback will be called |
890 | latency/jitter/inexactness (the watcher callback will be called |
758 | later). C<ev_io> watchers will not be affected. Setting this to a non-null |
891 | later). C<ev_io> watchers will not be affected. Setting this to a non-null |
… | |
… | |
760 | |
893 | |
761 | Many (busy) programs can usually benefit by setting the I/O collect |
894 | Many (busy) programs can usually benefit by setting the I/O collect |
762 | interval to a value near C<0.1> or so, which is often enough for |
895 | interval to a value near C<0.1> or so, which is often enough for |
763 | interactive servers (of course not for games), likewise for timeouts. It |
896 | interactive servers (of course not for games), likewise for timeouts. It |
764 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
897 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
765 | as this approaches the timing granularity of most systems. |
898 | as this approaches the timing granularity of most systems. Note that if |
|
|
899 | you do transactions with the outside world and you can't increase the |
|
|
900 | parallelity, then this setting will limit your transaction rate (if you |
|
|
901 | need to poll once per transaction and the I/O collect interval is 0.01, |
|
|
902 | then you can't do more than 100 transactions per second). |
766 | |
903 | |
767 | Setting the I<timeout collect interval> can improve the opportunity for |
904 | Setting the I<timeout collect interval> can improve the opportunity for |
768 | saving power, as the program will "bundle" timer callback invocations that |
905 | saving power, as the program will "bundle" timer callback invocations that |
769 | are "near" in time together, by delaying some, thus reducing the number of |
906 | are "near" in time together, by delaying some, thus reducing the number of |
770 | times the process sleeps and wakes up again. Another useful technique to |
907 | times the process sleeps and wakes up again. Another useful technique to |
771 | reduce iterations/wake-ups is to use C<ev_periodic> watchers and make sure |
908 | reduce iterations/wake-ups is to use C<ev_periodic> watchers and make sure |
772 | they fire on, say, one-second boundaries only. |
909 | they fire on, say, one-second boundaries only. |
773 | |
910 | |
|
|
911 | Example: we only need 0.1s timeout granularity, and we wish not to poll |
|
|
912 | more often than 100 times per second: |
|
|
913 | |
|
|
914 | ev_set_timeout_collect_interval (EV_DEFAULT_UC_ 0.1); |
|
|
915 | ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01); |
|
|
916 | |
|
|
917 | =item ev_invoke_pending (loop) |
|
|
918 | |
|
|
919 | This call will simply invoke all pending watchers while resetting their |
|
|
920 | pending state. Normally, C<ev_run> does this automatically when required, |
|
|
921 | but when overriding the invoke callback this call comes handy. This |
|
|
922 | function can be invoked from a watcher - this can be useful for example |
|
|
923 | when you want to do some lengthy calculation and want to pass further |
|
|
924 | event handling to another thread (you still have to make sure only one |
|
|
925 | thread executes within C<ev_invoke_pending> or C<ev_run> of course). |
|
|
926 | |
|
|
927 | =item int ev_pending_count (loop) |
|
|
928 | |
|
|
929 | Returns the number of pending watchers - zero indicates that no watchers |
|
|
930 | are pending. |
|
|
931 | |
|
|
932 | =item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P)) |
|
|
933 | |
|
|
934 | This overrides the invoke pending functionality of the loop: Instead of |
|
|
935 | invoking all pending watchers when there are any, C<ev_run> will call |
|
|
936 | this callback instead. This is useful, for example, when you want to |
|
|
937 | invoke the actual watchers inside another context (another thread etc.). |
|
|
938 | |
|
|
939 | If you want to reset the callback, use C<ev_invoke_pending> as new |
|
|
940 | callback. |
|
|
941 | |
|
|
942 | =item ev_set_loop_release_cb (loop, void (*release)(EV_P), void (*acquire)(EV_P)) |
|
|
943 | |
|
|
944 | Sometimes you want to share the same loop between multiple threads. This |
|
|
945 | can be done relatively simply by putting mutex_lock/unlock calls around |
|
|
946 | each call to a libev function. |
|
|
947 | |
|
|
948 | However, C<ev_run> can run an indefinite time, so it is not feasible |
|
|
949 | to wait for it to return. One way around this is to wake up the event |
|
|
950 | loop via C<ev_break> and C<av_async_send>, another way is to set these |
|
|
951 | I<release> and I<acquire> callbacks on the loop. |
|
|
952 | |
|
|
953 | When set, then C<release> will be called just before the thread is |
|
|
954 | suspended waiting for new events, and C<acquire> is called just |
|
|
955 | afterwards. |
|
|
956 | |
|
|
957 | Ideally, C<release> will just call your mutex_unlock function, and |
|
|
958 | C<acquire> will just call the mutex_lock function again. |
|
|
959 | |
|
|
960 | While event loop modifications are allowed between invocations of |
|
|
961 | C<release> and C<acquire> (that's their only purpose after all), no |
|
|
962 | modifications done will affect the event loop, i.e. adding watchers will |
|
|
963 | have no effect on the set of file descriptors being watched, or the time |
|
|
964 | waited. Use an C<ev_async> watcher to wake up C<ev_run> when you want it |
|
|
965 | to take note of any changes you made. |
|
|
966 | |
|
|
967 | In theory, threads executing C<ev_run> will be async-cancel safe between |
|
|
968 | invocations of C<release> and C<acquire>. |
|
|
969 | |
|
|
970 | See also the locking example in the C<THREADS> section later in this |
|
|
971 | document. |
|
|
972 | |
|
|
973 | =item ev_set_userdata (loop, void *data) |
|
|
974 | |
|
|
975 | =item ev_userdata (loop) |
|
|
976 | |
|
|
977 | Set and retrieve a single C<void *> associated with a loop. When |
|
|
978 | C<ev_set_userdata> has never been called, then C<ev_userdata> returns |
|
|
979 | C<0.> |
|
|
980 | |
|
|
981 | These two functions can be used to associate arbitrary data with a loop, |
|
|
982 | and are intended solely for the C<invoke_pending_cb>, C<release> and |
|
|
983 | C<acquire> callbacks described above, but of course can be (ab-)used for |
|
|
984 | any other purpose as well. |
|
|
985 | |
774 | =item ev_loop_verify (loop) |
986 | =item ev_verify (loop) |
775 | |
987 | |
776 | This function only does something when C<EV_VERIFY> support has been |
988 | This function only does something when C<EV_VERIFY> support has been |
777 | compiled in, which is the default for non-minimal builds. It tries to go |
989 | compiled in, which is the default for non-minimal builds. It tries to go |
778 | through all internal structures and checks them for validity. If anything |
990 | through all internal structures and checks them for validity. If anything |
779 | is found to be inconsistent, it will print an error message to standard |
991 | is found to be inconsistent, it will print an error message to standard |
… | |
… | |
790 | |
1002 | |
791 | In the following description, uppercase C<TYPE> in names stands for the |
1003 | In the following description, uppercase C<TYPE> in names stands for the |
792 | watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer |
1004 | watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer |
793 | watchers and C<ev_io_start> for I/O watchers. |
1005 | watchers and C<ev_io_start> for I/O watchers. |
794 | |
1006 | |
795 | A watcher is a structure that you create and register to record your |
1007 | A watcher is an opaque structure that you allocate and register to record |
796 | interest in some event. For instance, if you want to wait for STDIN to |
1008 | your interest in some event. To make a concrete example, imagine you want |
797 | become readable, you would create an C<ev_io> watcher for that: |
1009 | to wait for STDIN to become readable, you would create an C<ev_io> watcher |
|
|
1010 | for that: |
798 | |
1011 | |
799 | static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
1012 | static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
800 | { |
1013 | { |
801 | ev_io_stop (w); |
1014 | ev_io_stop (w); |
802 | ev_unloop (loop, EVUNLOOP_ALL); |
1015 | ev_break (loop, EVBREAK_ALL); |
803 | } |
1016 | } |
804 | |
1017 | |
805 | struct ev_loop *loop = ev_default_loop (0); |
1018 | struct ev_loop *loop = ev_default_loop (0); |
806 | |
1019 | |
807 | ev_io stdin_watcher; |
1020 | ev_io stdin_watcher; |
808 | |
1021 | |
809 | ev_init (&stdin_watcher, my_cb); |
1022 | ev_init (&stdin_watcher, my_cb); |
810 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
1023 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
811 | ev_io_start (loop, &stdin_watcher); |
1024 | ev_io_start (loop, &stdin_watcher); |
812 | |
1025 | |
813 | ev_loop (loop, 0); |
1026 | ev_run (loop, 0); |
814 | |
1027 | |
815 | As you can see, you are responsible for allocating the memory for your |
1028 | As you can see, you are responsible for allocating the memory for your |
816 | watcher structures (and it is I<usually> a bad idea to do this on the |
1029 | watcher structures (and it is I<usually> a bad idea to do this on the |
817 | stack). |
1030 | stack). |
818 | |
1031 | |
819 | Each watcher has an associated watcher structure (called C<struct ev_TYPE> |
1032 | Each watcher has an associated watcher structure (called C<struct ev_TYPE> |
820 | or simply C<ev_TYPE>, as typedefs are provided for all watcher structs). |
1033 | or simply C<ev_TYPE>, as typedefs are provided for all watcher structs). |
821 | |
1034 | |
822 | Each watcher structure must be initialised by a call to C<ev_init |
1035 | Each watcher structure must be initialised by a call to C<ev_init (watcher |
823 | (watcher *, callback)>, which expects a callback to be provided. This |
1036 | *, callback)>, which expects a callback to be provided. This callback is |
824 | callback gets invoked each time the event occurs (or, in the case of I/O |
1037 | invoked each time the event occurs (or, in the case of I/O watchers, each |
825 | watchers, each time the event loop detects that the file descriptor given |
1038 | time the event loop detects that the file descriptor given is readable |
826 | is readable and/or writable). |
1039 | and/or writable). |
827 | |
1040 | |
828 | Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >> |
1041 | Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >> |
829 | macro to configure it, with arguments specific to the watcher type. There |
1042 | macro to configure it, with arguments specific to the watcher type. There |
830 | is also a macro to combine initialisation and setting in one call: C<< |
1043 | is also a macro to combine initialisation and setting in one call: C<< |
831 | ev_TYPE_init (watcher *, callback, ...) >>. |
1044 | ev_TYPE_init (watcher *, callback, ...) >>. |
… | |
… | |
854 | =item C<EV_WRITE> |
1067 | =item C<EV_WRITE> |
855 | |
1068 | |
856 | The file descriptor in the C<ev_io> watcher has become readable and/or |
1069 | The file descriptor in the C<ev_io> watcher has become readable and/or |
857 | writable. |
1070 | writable. |
858 | |
1071 | |
859 | =item C<EV_TIMEOUT> |
1072 | =item C<EV_TIMER> |
860 | |
1073 | |
861 | The C<ev_timer> watcher has timed out. |
1074 | The C<ev_timer> watcher has timed out. |
862 | |
1075 | |
863 | =item C<EV_PERIODIC> |
1076 | =item C<EV_PERIODIC> |
864 | |
1077 | |
… | |
… | |
882 | |
1095 | |
883 | =item C<EV_PREPARE> |
1096 | =item C<EV_PREPARE> |
884 | |
1097 | |
885 | =item C<EV_CHECK> |
1098 | =item C<EV_CHECK> |
886 | |
1099 | |
887 | All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts |
1100 | All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts |
888 | to gather new events, and all C<ev_check> watchers are invoked just after |
1101 | to gather new events, and all C<ev_check> watchers are invoked just after |
889 | C<ev_loop> has gathered them, but before it invokes any callbacks for any |
1102 | C<ev_run> has gathered them, but before it invokes any callbacks for any |
890 | received events. Callbacks of both watcher types can start and stop as |
1103 | received events. Callbacks of both watcher types can start and stop as |
891 | many watchers as they want, and all of them will be taken into account |
1104 | many watchers as they want, and all of them will be taken into account |
892 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
1105 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
893 | C<ev_loop> from blocking). |
1106 | C<ev_run> from blocking). |
894 | |
1107 | |
895 | =item C<EV_EMBED> |
1108 | =item C<EV_EMBED> |
896 | |
1109 | |
897 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
1110 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
898 | |
1111 | |
… | |
… | |
902 | C<ev_fork>). |
1115 | C<ev_fork>). |
903 | |
1116 | |
904 | =item C<EV_ASYNC> |
1117 | =item C<EV_ASYNC> |
905 | |
1118 | |
906 | The given async watcher has been asynchronously notified (see C<ev_async>). |
1119 | The given async watcher has been asynchronously notified (see C<ev_async>). |
|
|
1120 | |
|
|
1121 | =item C<EV_CUSTOM> |
|
|
1122 | |
|
|
1123 | Not ever sent (or otherwise used) by libev itself, but can be freely used |
|
|
1124 | by libev users to signal watchers (e.g. via C<ev_feed_event>). |
907 | |
1125 | |
908 | =item C<EV_ERROR> |
1126 | =item C<EV_ERROR> |
909 | |
1127 | |
910 | An unspecified error has occurred, the watcher has been stopped. This might |
1128 | An unspecified error has occurred, the watcher has been stopped. This might |
911 | happen because the watcher could not be properly started because libev |
1129 | happen because the watcher could not be properly started because libev |
… | |
… | |
924 | programs, though, as the fd could already be closed and reused for another |
1142 | programs, though, as the fd could already be closed and reused for another |
925 | thing, so beware. |
1143 | thing, so beware. |
926 | |
1144 | |
927 | =back |
1145 | =back |
928 | |
1146 | |
|
|
1147 | =head2 WATCHER STATES |
|
|
1148 | |
|
|
1149 | There are various watcher states mentioned throughout this manual - |
|
|
1150 | active, pending and so on. In this section these states and the rules to |
|
|
1151 | transition between them will be described in more detail - and while these |
|
|
1152 | rules might look complicated, they usually do "the right thing". |
|
|
1153 | |
|
|
1154 | =over 4 |
|
|
1155 | |
|
|
1156 | =item initialiased |
|
|
1157 | |
|
|
1158 | Before a watcher can be registered with the event looop it has to be |
|
|
1159 | initialised. This can be done with a call to C<ev_TYPE_init>, or calls to |
|
|
1160 | C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function. |
|
|
1161 | |
|
|
1162 | In this state it is simply some block of memory that is suitable for use |
|
|
1163 | in an event loop. It can be moved around, freed, reused etc. at will. |
|
|
1164 | |
|
|
1165 | =item started/running/active |
|
|
1166 | |
|
|
1167 | Once a watcher has been started with a call to C<ev_TYPE_start> it becomes |
|
|
1168 | property of the event loop, and is actively waiting for events. While in |
|
|
1169 | this state it cannot be accessed (except in a few documented ways), moved, |
|
|
1170 | freed or anything else - the only legal thing is to keep a pointer to it, |
|
|
1171 | and call libev functions on it that are documented to work on active watchers. |
|
|
1172 | |
|
|
1173 | =item pending |
|
|
1174 | |
|
|
1175 | If a watcher is active and libev determines that an event it is interested |
|
|
1176 | in has occurred (such as a timer expiring), it will become pending. It will |
|
|
1177 | stay in this pending state until either it is stopped or its callback is |
|
|
1178 | about to be invoked, so it is not normally pending inside the watcher |
|
|
1179 | callback. |
|
|
1180 | |
|
|
1181 | The watcher might or might not be active while it is pending (for example, |
|
|
1182 | an expired non-repeating timer can be pending but no longer active). If it |
|
|
1183 | is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>), |
|
|
1184 | but it is still property of the event loop at this time, so cannot be |
|
|
1185 | moved, freed or reused. And if it is active the rules described in the |
|
|
1186 | previous item still apply. |
|
|
1187 | |
|
|
1188 | It is also possible to feed an event on a watcher that is not active (e.g. |
|
|
1189 | via C<ev_feed_event>), in which case it becomes pending without being |
|
|
1190 | active. |
|
|
1191 | |
|
|
1192 | =item stopped |
|
|
1193 | |
|
|
1194 | A watcher can be stopped implicitly by libev (in which case it might still |
|
|
1195 | be pending), or explicitly by calling its C<ev_TYPE_stop> function. The |
|
|
1196 | latter will clear any pending state the watcher might be in, regardless |
|
|
1197 | of whether it was active or not, so stopping a watcher explicitly before |
|
|
1198 | freeing it is often a good idea. |
|
|
1199 | |
|
|
1200 | While stopped (and not pending) the watcher is essentially in the |
|
|
1201 | initialised state, that is it can be reused, moved, modified in any way |
|
|
1202 | you wish. |
|
|
1203 | |
|
|
1204 | =back |
|
|
1205 | |
929 | =head2 GENERIC WATCHER FUNCTIONS |
1206 | =head2 GENERIC WATCHER FUNCTIONS |
930 | |
1207 | |
931 | =over 4 |
1208 | =over 4 |
932 | |
1209 | |
933 | =item C<ev_init> (ev_TYPE *watcher, callback) |
1210 | =item C<ev_init> (ev_TYPE *watcher, callback) |
… | |
… | |
949 | |
1226 | |
950 | ev_io w; |
1227 | ev_io w; |
951 | ev_init (&w, my_cb); |
1228 | ev_init (&w, my_cb); |
952 | ev_io_set (&w, STDIN_FILENO, EV_READ); |
1229 | ev_io_set (&w, STDIN_FILENO, EV_READ); |
953 | |
1230 | |
954 | =item C<ev_TYPE_set> (ev_TYPE *, [args]) |
1231 | =item C<ev_TYPE_set> (ev_TYPE *watcher, [args]) |
955 | |
1232 | |
956 | This macro initialises the type-specific parts of a watcher. You need to |
1233 | This macro initialises the type-specific parts of a watcher. You need to |
957 | call C<ev_init> at least once before you call this macro, but you can |
1234 | call C<ev_init> at least once before you call this macro, but you can |
958 | call C<ev_TYPE_set> any number of times. You must not, however, call this |
1235 | call C<ev_TYPE_set> any number of times. You must not, however, call this |
959 | macro on a watcher that is active (it can be pending, however, which is a |
1236 | macro on a watcher that is active (it can be pending, however, which is a |
… | |
… | |
972 | |
1249 | |
973 | Example: Initialise and set an C<ev_io> watcher in one step. |
1250 | Example: Initialise and set an C<ev_io> watcher in one step. |
974 | |
1251 | |
975 | ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
1252 | ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
976 | |
1253 | |
977 | =item C<ev_TYPE_start> (loop *, ev_TYPE *watcher) |
1254 | =item C<ev_TYPE_start> (loop, ev_TYPE *watcher) |
978 | |
1255 | |
979 | Starts (activates) the given watcher. Only active watchers will receive |
1256 | Starts (activates) the given watcher. Only active watchers will receive |
980 | events. If the watcher is already active nothing will happen. |
1257 | events. If the watcher is already active nothing will happen. |
981 | |
1258 | |
982 | Example: Start the C<ev_io> watcher that is being abused as example in this |
1259 | Example: Start the C<ev_io> watcher that is being abused as example in this |
983 | whole section. |
1260 | whole section. |
984 | |
1261 | |
985 | ev_io_start (EV_DEFAULT_UC, &w); |
1262 | ev_io_start (EV_DEFAULT_UC, &w); |
986 | |
1263 | |
987 | =item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher) |
1264 | =item C<ev_TYPE_stop> (loop, ev_TYPE *watcher) |
988 | |
1265 | |
989 | Stops the given watcher if active, and clears the pending status (whether |
1266 | Stops the given watcher if active, and clears the pending status (whether |
990 | the watcher was active or not). |
1267 | the watcher was active or not). |
991 | |
1268 | |
992 | It is possible that stopped watchers are pending - for example, |
1269 | It is possible that stopped watchers are pending - for example, |
… | |
… | |
1017 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1294 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1018 | |
1295 | |
1019 | Change the callback. You can change the callback at virtually any time |
1296 | Change the callback. You can change the callback at virtually any time |
1020 | (modulo threads). |
1297 | (modulo threads). |
1021 | |
1298 | |
1022 | =item ev_set_priority (ev_TYPE *watcher, priority) |
1299 | =item ev_set_priority (ev_TYPE *watcher, int priority) |
1023 | |
1300 | |
1024 | =item int ev_priority (ev_TYPE *watcher) |
1301 | =item int ev_priority (ev_TYPE *watcher) |
1025 | |
1302 | |
1026 | Set and query the priority of the watcher. The priority is a small |
1303 | Set and query the priority of the watcher. The priority is a small |
1027 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
1304 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
1028 | (default: C<-2>). Pending watchers with higher priority will be invoked |
1305 | (default: C<-2>). Pending watchers with higher priority will be invoked |
1029 | before watchers with lower priority, but priority will not keep watchers |
1306 | before watchers with lower priority, but priority will not keep watchers |
1030 | from being executed (except for C<ev_idle> watchers). |
1307 | from being executed (except for C<ev_idle> watchers). |
1031 | |
1308 | |
1032 | This means that priorities are I<only> used for ordering callback |
|
|
1033 | invocation after new events have been received. This is useful, for |
|
|
1034 | example, to reduce latency after idling, or more often, to bind two |
|
|
1035 | watchers on the same event and make sure one is called first. |
|
|
1036 | |
|
|
1037 | If you need to suppress invocation when higher priority events are pending |
1309 | If you need to suppress invocation when higher priority events are pending |
1038 | you need to look at C<ev_idle> watchers, which provide this functionality. |
1310 | you need to look at C<ev_idle> watchers, which provide this functionality. |
1039 | |
1311 | |
1040 | You I<must not> change the priority of a watcher as long as it is active or |
1312 | You I<must not> change the priority of a watcher as long as it is active or |
1041 | pending. |
1313 | pending. |
1042 | |
|
|
1043 | The default priority used by watchers when no priority has been set is |
|
|
1044 | always C<0>, which is supposed to not be too high and not be too low :). |
|
|
1045 | |
1314 | |
1046 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
1315 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
1047 | fine, as long as you do not mind that the priority value you query might |
1316 | fine, as long as you do not mind that the priority value you query might |
1048 | or might not have been clamped to the valid range. |
1317 | or might not have been clamped to the valid range. |
|
|
1318 | |
|
|
1319 | The default priority used by watchers when no priority has been set is |
|
|
1320 | always C<0>, which is supposed to not be too high and not be too low :). |
|
|
1321 | |
|
|
1322 | See L<WATCHER PRIORITY MODELS>, below, for a more thorough treatment of |
|
|
1323 | priorities. |
1049 | |
1324 | |
1050 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
1325 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
1051 | |
1326 | |
1052 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
1327 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
1053 | C<loop> nor C<revents> need to be valid as long as the watcher callback |
1328 | C<loop> nor C<revents> need to be valid as long as the watcher callback |
… | |
… | |
1060 | returns its C<revents> bitset (as if its callback was invoked). If the |
1335 | returns its C<revents> bitset (as if its callback was invoked). If the |
1061 | watcher isn't pending it does nothing and returns C<0>. |
1336 | watcher isn't pending it does nothing and returns C<0>. |
1062 | |
1337 | |
1063 | Sometimes it can be useful to "poll" a watcher instead of waiting for its |
1338 | Sometimes it can be useful to "poll" a watcher instead of waiting for its |
1064 | callback to be invoked, which can be accomplished with this function. |
1339 | callback to be invoked, which can be accomplished with this function. |
|
|
1340 | |
|
|
1341 | =item ev_feed_event (loop, ev_TYPE *watcher, int revents) |
|
|
1342 | |
|
|
1343 | Feeds the given event set into the event loop, as if the specified event |
|
|
1344 | had happened for the specified watcher (which must be a pointer to an |
|
|
1345 | initialised but not necessarily started event watcher). Obviously you must |
|
|
1346 | not free the watcher as long as it has pending events. |
|
|
1347 | |
|
|
1348 | Stopping the watcher, letting libev invoke it, or calling |
|
|
1349 | C<ev_clear_pending> will clear the pending event, even if the watcher was |
|
|
1350 | not started in the first place. |
|
|
1351 | |
|
|
1352 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
|
|
1353 | functions that do not need a watcher. |
1065 | |
1354 | |
1066 | =back |
1355 | =back |
1067 | |
1356 | |
1068 | |
1357 | |
1069 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
1358 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
… | |
… | |
1118 | #include <stddef.h> |
1407 | #include <stddef.h> |
1119 | |
1408 | |
1120 | static void |
1409 | static void |
1121 | t1_cb (EV_P_ ev_timer *w, int revents) |
1410 | t1_cb (EV_P_ ev_timer *w, int revents) |
1122 | { |
1411 | { |
1123 | struct my_biggy big = (struct my_biggy * |
1412 | struct my_biggy big = (struct my_biggy *) |
1124 | (((char *)w) - offsetof (struct my_biggy, t1)); |
1413 | (((char *)w) - offsetof (struct my_biggy, t1)); |
1125 | } |
1414 | } |
1126 | |
1415 | |
1127 | static void |
1416 | static void |
1128 | t2_cb (EV_P_ ev_timer *w, int revents) |
1417 | t2_cb (EV_P_ ev_timer *w, int revents) |
1129 | { |
1418 | { |
1130 | struct my_biggy big = (struct my_biggy * |
1419 | struct my_biggy big = (struct my_biggy *) |
1131 | (((char *)w) - offsetof (struct my_biggy, t2)); |
1420 | (((char *)w) - offsetof (struct my_biggy, t2)); |
1132 | } |
1421 | } |
|
|
1422 | |
|
|
1423 | =head2 WATCHER PRIORITY MODELS |
|
|
1424 | |
|
|
1425 | Many event loops support I<watcher priorities>, which are usually small |
|
|
1426 | integers that influence the ordering of event callback invocation |
|
|
1427 | between watchers in some way, all else being equal. |
|
|
1428 | |
|
|
1429 | In libev, Watcher priorities can be set using C<ev_set_priority>. See its |
|
|
1430 | description for the more technical details such as the actual priority |
|
|
1431 | range. |
|
|
1432 | |
|
|
1433 | There are two common ways how these these priorities are being interpreted |
|
|
1434 | by event loops: |
|
|
1435 | |
|
|
1436 | In the more common lock-out model, higher priorities "lock out" invocation |
|
|
1437 | of lower priority watchers, which means as long as higher priority |
|
|
1438 | watchers receive events, lower priority watchers are not being invoked. |
|
|
1439 | |
|
|
1440 | The less common only-for-ordering model uses priorities solely to order |
|
|
1441 | callback invocation within a single event loop iteration: Higher priority |
|
|
1442 | watchers are invoked before lower priority ones, but they all get invoked |
|
|
1443 | before polling for new events. |
|
|
1444 | |
|
|
1445 | Libev uses the second (only-for-ordering) model for all its watchers |
|
|
1446 | except for idle watchers (which use the lock-out model). |
|
|
1447 | |
|
|
1448 | The rationale behind this is that implementing the lock-out model for |
|
|
1449 | watchers is not well supported by most kernel interfaces, and most event |
|
|
1450 | libraries will just poll for the same events again and again as long as |
|
|
1451 | their callbacks have not been executed, which is very inefficient in the |
|
|
1452 | common case of one high-priority watcher locking out a mass of lower |
|
|
1453 | priority ones. |
|
|
1454 | |
|
|
1455 | Static (ordering) priorities are most useful when you have two or more |
|
|
1456 | watchers handling the same resource: a typical usage example is having an |
|
|
1457 | C<ev_io> watcher to receive data, and an associated C<ev_timer> to handle |
|
|
1458 | timeouts. Under load, data might be received while the program handles |
|
|
1459 | other jobs, but since timers normally get invoked first, the timeout |
|
|
1460 | handler will be executed before checking for data. In that case, giving |
|
|
1461 | the timer a lower priority than the I/O watcher ensures that I/O will be |
|
|
1462 | handled first even under adverse conditions (which is usually, but not |
|
|
1463 | always, what you want). |
|
|
1464 | |
|
|
1465 | Since idle watchers use the "lock-out" model, meaning that idle watchers |
|
|
1466 | will only be executed when no same or higher priority watchers have |
|
|
1467 | received events, they can be used to implement the "lock-out" model when |
|
|
1468 | required. |
|
|
1469 | |
|
|
1470 | For example, to emulate how many other event libraries handle priorities, |
|
|
1471 | you can associate an C<ev_idle> watcher to each such watcher, and in |
|
|
1472 | the normal watcher callback, you just start the idle watcher. The real |
|
|
1473 | processing is done in the idle watcher callback. This causes libev to |
|
|
1474 | continuously poll and process kernel event data for the watcher, but when |
|
|
1475 | the lock-out case is known to be rare (which in turn is rare :), this is |
|
|
1476 | workable. |
|
|
1477 | |
|
|
1478 | Usually, however, the lock-out model implemented that way will perform |
|
|
1479 | miserably under the type of load it was designed to handle. In that case, |
|
|
1480 | it might be preferable to stop the real watcher before starting the |
|
|
1481 | idle watcher, so the kernel will not have to process the event in case |
|
|
1482 | the actual processing will be delayed for considerable time. |
|
|
1483 | |
|
|
1484 | Here is an example of an I/O watcher that should run at a strictly lower |
|
|
1485 | priority than the default, and which should only process data when no |
|
|
1486 | other events are pending: |
|
|
1487 | |
|
|
1488 | ev_idle idle; // actual processing watcher |
|
|
1489 | ev_io io; // actual event watcher |
|
|
1490 | |
|
|
1491 | static void |
|
|
1492 | io_cb (EV_P_ ev_io *w, int revents) |
|
|
1493 | { |
|
|
1494 | // stop the I/O watcher, we received the event, but |
|
|
1495 | // are not yet ready to handle it. |
|
|
1496 | ev_io_stop (EV_A_ w); |
|
|
1497 | |
|
|
1498 | // start the idle watcher to handle the actual event. |
|
|
1499 | // it will not be executed as long as other watchers |
|
|
1500 | // with the default priority are receiving events. |
|
|
1501 | ev_idle_start (EV_A_ &idle); |
|
|
1502 | } |
|
|
1503 | |
|
|
1504 | static void |
|
|
1505 | idle_cb (EV_P_ ev_idle *w, int revents) |
|
|
1506 | { |
|
|
1507 | // actual processing |
|
|
1508 | read (STDIN_FILENO, ...); |
|
|
1509 | |
|
|
1510 | // have to start the I/O watcher again, as |
|
|
1511 | // we have handled the event |
|
|
1512 | ev_io_start (EV_P_ &io); |
|
|
1513 | } |
|
|
1514 | |
|
|
1515 | // initialisation |
|
|
1516 | ev_idle_init (&idle, idle_cb); |
|
|
1517 | ev_io_init (&io, io_cb, STDIN_FILENO, EV_READ); |
|
|
1518 | ev_io_start (EV_DEFAULT_ &io); |
|
|
1519 | |
|
|
1520 | In the "real" world, it might also be beneficial to start a timer, so that |
|
|
1521 | low-priority connections can not be locked out forever under load. This |
|
|
1522 | enables your program to keep a lower latency for important connections |
|
|
1523 | during short periods of high load, while not completely locking out less |
|
|
1524 | important ones. |
1133 | |
1525 | |
1134 | |
1526 | |
1135 | =head1 WATCHER TYPES |
1527 | =head1 WATCHER TYPES |
1136 | |
1528 | |
1137 | This section describes each watcher in detail, but will not repeat |
1529 | This section describes each watcher in detail, but will not repeat |
… | |
… | |
1163 | descriptors to non-blocking mode is also usually a good idea (but not |
1555 | descriptors to non-blocking mode is also usually a good idea (but not |
1164 | required if you know what you are doing). |
1556 | required if you know what you are doing). |
1165 | |
1557 | |
1166 | If you cannot use non-blocking mode, then force the use of a |
1558 | If you cannot use non-blocking mode, then force the use of a |
1167 | known-to-be-good backend (at the time of this writing, this includes only |
1559 | known-to-be-good backend (at the time of this writing, this includes only |
1168 | C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). |
1560 | C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file |
|
|
1561 | descriptors for which non-blocking operation makes no sense (such as |
|
|
1562 | files) - libev doesn't guarantee any specific behaviour in that case. |
1169 | |
1563 | |
1170 | Another thing you have to watch out for is that it is quite easy to |
1564 | Another thing you have to watch out for is that it is quite easy to |
1171 | receive "spurious" readiness notifications, that is your callback might |
1565 | receive "spurious" readiness notifications, that is your callback might |
1172 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1566 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1173 | because there is no data. Not only are some backends known to create a |
1567 | because there is no data. Not only are some backends known to create a |
… | |
… | |
1238 | |
1632 | |
1239 | So when you encounter spurious, unexplained daemon exits, make sure you |
1633 | So when you encounter spurious, unexplained daemon exits, make sure you |
1240 | ignore SIGPIPE (and maybe make sure you log the exit status of your daemon |
1634 | ignore SIGPIPE (and maybe make sure you log the exit status of your daemon |
1241 | somewhere, as that would have given you a big clue). |
1635 | somewhere, as that would have given you a big clue). |
1242 | |
1636 | |
|
|
1637 | =head3 The special problem of accept()ing when you can't |
|
|
1638 | |
|
|
1639 | Many implementations of the POSIX C<accept> function (for example, |
|
|
1640 | found in post-2004 Linux) have the peculiar behaviour of not removing a |
|
|
1641 | connection from the pending queue in all error cases. |
|
|
1642 | |
|
|
1643 | For example, larger servers often run out of file descriptors (because |
|
|
1644 | of resource limits), causing C<accept> to fail with C<ENFILE> but not |
|
|
1645 | rejecting the connection, leading to libev signalling readiness on |
|
|
1646 | the next iteration again (the connection still exists after all), and |
|
|
1647 | typically causing the program to loop at 100% CPU usage. |
|
|
1648 | |
|
|
1649 | Unfortunately, the set of errors that cause this issue differs between |
|
|
1650 | operating systems, there is usually little the app can do to remedy the |
|
|
1651 | situation, and no known thread-safe method of removing the connection to |
|
|
1652 | cope with overload is known (to me). |
|
|
1653 | |
|
|
1654 | One of the easiest ways to handle this situation is to just ignore it |
|
|
1655 | - when the program encounters an overload, it will just loop until the |
|
|
1656 | situation is over. While this is a form of busy waiting, no OS offers an |
|
|
1657 | event-based way to handle this situation, so it's the best one can do. |
|
|
1658 | |
|
|
1659 | A better way to handle the situation is to log any errors other than |
|
|
1660 | C<EAGAIN> and C<EWOULDBLOCK>, making sure not to flood the log with such |
|
|
1661 | messages, and continue as usual, which at least gives the user an idea of |
|
|
1662 | what could be wrong ("raise the ulimit!"). For extra points one could stop |
|
|
1663 | the C<ev_io> watcher on the listening fd "for a while", which reduces CPU |
|
|
1664 | usage. |
|
|
1665 | |
|
|
1666 | If your program is single-threaded, then you could also keep a dummy file |
|
|
1667 | descriptor for overload situations (e.g. by opening F</dev/null>), and |
|
|
1668 | when you run into C<ENFILE> or C<EMFILE>, close it, run C<accept>, |
|
|
1669 | close that fd, and create a new dummy fd. This will gracefully refuse |
|
|
1670 | clients under typical overload conditions. |
|
|
1671 | |
|
|
1672 | The last way to handle it is to simply log the error and C<exit>, as |
|
|
1673 | is often done with C<malloc> failures, but this results in an easy |
|
|
1674 | opportunity for a DoS attack. |
1243 | |
1675 | |
1244 | =head3 Watcher-Specific Functions |
1676 | =head3 Watcher-Specific Functions |
1245 | |
1677 | |
1246 | =over 4 |
1678 | =over 4 |
1247 | |
1679 | |
… | |
… | |
1279 | ... |
1711 | ... |
1280 | struct ev_loop *loop = ev_default_init (0); |
1712 | struct ev_loop *loop = ev_default_init (0); |
1281 | ev_io stdin_readable; |
1713 | ev_io stdin_readable; |
1282 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1714 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1283 | ev_io_start (loop, &stdin_readable); |
1715 | ev_io_start (loop, &stdin_readable); |
1284 | ev_loop (loop, 0); |
1716 | ev_run (loop, 0); |
1285 | |
1717 | |
1286 | |
1718 | |
1287 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
1719 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
1288 | |
1720 | |
1289 | Timer watchers are simple relative timers that generate an event after a |
1721 | Timer watchers are simple relative timers that generate an event after a |
… | |
… | |
1294 | year, it will still time out after (roughly) one hour. "Roughly" because |
1726 | year, it will still time out after (roughly) one hour. "Roughly" because |
1295 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1727 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1296 | monotonic clock option helps a lot here). |
1728 | monotonic clock option helps a lot here). |
1297 | |
1729 | |
1298 | The callback is guaranteed to be invoked only I<after> its timeout has |
1730 | The callback is guaranteed to be invoked only I<after> its timeout has |
1299 | passed, but if multiple timers become ready during the same loop iteration |
1731 | passed (not I<at>, so on systems with very low-resolution clocks this |
1300 | then order of execution is undefined. |
1732 | might introduce a small delay). If multiple timers become ready during the |
|
|
1733 | same loop iteration then the ones with earlier time-out values are invoked |
|
|
1734 | before ones of the same priority with later time-out values (but this is |
|
|
1735 | no longer true when a callback calls C<ev_run> recursively). |
1301 | |
1736 | |
1302 | =head3 Be smart about timeouts |
1737 | =head3 Be smart about timeouts |
1303 | |
1738 | |
1304 | Many real-world problems involve some kind of timeout, usually for error |
1739 | Many real-world problems involve some kind of timeout, usually for error |
1305 | recovery. A typical example is an HTTP request - if the other side hangs, |
1740 | recovery. A typical example is an HTTP request - if the other side hangs, |
… | |
… | |
1349 | C<after> argument to C<ev_timer_set>, and only ever use the C<repeat> |
1784 | C<after> argument to C<ev_timer_set>, and only ever use the C<repeat> |
1350 | member and C<ev_timer_again>. |
1785 | member and C<ev_timer_again>. |
1351 | |
1786 | |
1352 | At start: |
1787 | At start: |
1353 | |
1788 | |
1354 | ev_timer_init (timer, callback); |
1789 | ev_init (timer, callback); |
1355 | timer->repeat = 60.; |
1790 | timer->repeat = 60.; |
1356 | ev_timer_again (loop, timer); |
1791 | ev_timer_again (loop, timer); |
1357 | |
1792 | |
1358 | Each time there is some activity: |
1793 | Each time there is some activity: |
1359 | |
1794 | |
… | |
… | |
1391 | ev_tstamp timeout = last_activity + 60.; |
1826 | ev_tstamp timeout = last_activity + 60.; |
1392 | |
1827 | |
1393 | // if last_activity + 60. is older than now, we did time out |
1828 | // if last_activity + 60. is older than now, we did time out |
1394 | if (timeout < now) |
1829 | if (timeout < now) |
1395 | { |
1830 | { |
1396 | // timeout occured, take action |
1831 | // timeout occurred, take action |
1397 | } |
1832 | } |
1398 | else |
1833 | else |
1399 | { |
1834 | { |
1400 | // callback was invoked, but there was some activity, re-arm |
1835 | // callback was invoked, but there was some activity, re-arm |
1401 | // the watcher to fire in last_activity + 60, which is |
1836 | // the watcher to fire in last_activity + 60, which is |
1402 | // guaranteed to be in the future, so "again" is positive: |
1837 | // guaranteed to be in the future, so "again" is positive: |
1403 | w->again = timeout - now; |
1838 | w->repeat = timeout - now; |
1404 | ev_timer_again (EV_A_ w); |
1839 | ev_timer_again (EV_A_ w); |
1405 | } |
1840 | } |
1406 | } |
1841 | } |
1407 | |
1842 | |
1408 | To summarise the callback: first calculate the real timeout (defined |
1843 | To summarise the callback: first calculate the real timeout (defined |
… | |
… | |
1421 | |
1856 | |
1422 | To start the timer, simply initialise the watcher and set C<last_activity> |
1857 | To start the timer, simply initialise the watcher and set C<last_activity> |
1423 | to the current time (meaning we just have some activity :), then call the |
1858 | to the current time (meaning we just have some activity :), then call the |
1424 | callback, which will "do the right thing" and start the timer: |
1859 | callback, which will "do the right thing" and start the timer: |
1425 | |
1860 | |
1426 | ev_timer_init (timer, callback); |
1861 | ev_init (timer, callback); |
1427 | last_activity = ev_now (loop); |
1862 | last_activity = ev_now (loop); |
1428 | callback (loop, timer, EV_TIMEOUT); |
1863 | callback (loop, timer, EV_TIMER); |
1429 | |
1864 | |
1430 | And when there is some activity, simply store the current time in |
1865 | And when there is some activity, simply store the current time in |
1431 | C<last_activity>, no libev calls at all: |
1866 | C<last_activity>, no libev calls at all: |
1432 | |
1867 | |
1433 | last_actiivty = ev_now (loop); |
1868 | last_activity = ev_now (loop); |
1434 | |
1869 | |
1435 | This technique is slightly more complex, but in most cases where the |
1870 | This technique is slightly more complex, but in most cases where the |
1436 | time-out is unlikely to be triggered, much more efficient. |
1871 | time-out is unlikely to be triggered, much more efficient. |
1437 | |
1872 | |
1438 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
1873 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
… | |
… | |
1476 | |
1911 | |
1477 | =head3 The special problem of time updates |
1912 | =head3 The special problem of time updates |
1478 | |
1913 | |
1479 | Establishing the current time is a costly operation (it usually takes at |
1914 | Establishing the current time is a costly operation (it usually takes at |
1480 | least two system calls): EV therefore updates its idea of the current |
1915 | least two system calls): EV therefore updates its idea of the current |
1481 | time only before and after C<ev_loop> collects new events, which causes a |
1916 | time only before and after C<ev_run> collects new events, which causes a |
1482 | growing difference between C<ev_now ()> and C<ev_time ()> when handling |
1917 | growing difference between C<ev_now ()> and C<ev_time ()> when handling |
1483 | lots of events in one iteration. |
1918 | lots of events in one iteration. |
1484 | |
1919 | |
1485 | The relative timeouts are calculated relative to the C<ev_now ()> |
1920 | The relative timeouts are calculated relative to the C<ev_now ()> |
1486 | time. This is usually the right thing as this timestamp refers to the time |
1921 | time. This is usually the right thing as this timestamp refers to the time |
… | |
… | |
1492 | |
1927 | |
1493 | If the event loop is suspended for a long time, you can also force an |
1928 | If the event loop is suspended for a long time, you can also force an |
1494 | update of the time returned by C<ev_now ()> by calling C<ev_now_update |
1929 | update of the time returned by C<ev_now ()> by calling C<ev_now_update |
1495 | ()>. |
1930 | ()>. |
1496 | |
1931 | |
|
|
1932 | =head3 The special problems of suspended animation |
|
|
1933 | |
|
|
1934 | When you leave the server world it is quite customary to hit machines that |
|
|
1935 | can suspend/hibernate - what happens to the clocks during such a suspend? |
|
|
1936 | |
|
|
1937 | Some quick tests made with a Linux 2.6.28 indicate that a suspend freezes |
|
|
1938 | all processes, while the clocks (C<times>, C<CLOCK_MONOTONIC>) continue |
|
|
1939 | to run until the system is suspended, but they will not advance while the |
|
|
1940 | system is suspended. That means, on resume, it will be as if the program |
|
|
1941 | was frozen for a few seconds, but the suspend time will not be counted |
|
|
1942 | towards C<ev_timer> when a monotonic clock source is used. The real time |
|
|
1943 | clock advanced as expected, but if it is used as sole clocksource, then a |
|
|
1944 | long suspend would be detected as a time jump by libev, and timers would |
|
|
1945 | be adjusted accordingly. |
|
|
1946 | |
|
|
1947 | I would not be surprised to see different behaviour in different between |
|
|
1948 | operating systems, OS versions or even different hardware. |
|
|
1949 | |
|
|
1950 | The other form of suspend (job control, or sending a SIGSTOP) will see a |
|
|
1951 | time jump in the monotonic clocks and the realtime clock. If the program |
|
|
1952 | is suspended for a very long time, and monotonic clock sources are in use, |
|
|
1953 | then you can expect C<ev_timer>s to expire as the full suspension time |
|
|
1954 | will be counted towards the timers. When no monotonic clock source is in |
|
|
1955 | use, then libev will again assume a timejump and adjust accordingly. |
|
|
1956 | |
|
|
1957 | It might be beneficial for this latter case to call C<ev_suspend> |
|
|
1958 | and C<ev_resume> in code that handles C<SIGTSTP>, to at least get |
|
|
1959 | deterministic behaviour in this case (you can do nothing against |
|
|
1960 | C<SIGSTOP>). |
|
|
1961 | |
1497 | =head3 Watcher-Specific Functions and Data Members |
1962 | =head3 Watcher-Specific Functions and Data Members |
1498 | |
1963 | |
1499 | =over 4 |
1964 | =over 4 |
1500 | |
1965 | |
1501 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
1966 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
… | |
… | |
1524 | If the timer is started but non-repeating, stop it (as if it timed out). |
1989 | If the timer is started but non-repeating, stop it (as if it timed out). |
1525 | |
1990 | |
1526 | If the timer is repeating, either start it if necessary (with the |
1991 | If the timer is repeating, either start it if necessary (with the |
1527 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1992 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1528 | |
1993 | |
1529 | This sounds a bit complicated, see "Be smart about timeouts", above, for a |
1994 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
1530 | usage example. |
1995 | usage example. |
|
|
1996 | |
|
|
1997 | =item ev_tstamp ev_timer_remaining (loop, ev_timer *) |
|
|
1998 | |
|
|
1999 | Returns the remaining time until a timer fires. If the timer is active, |
|
|
2000 | then this time is relative to the current event loop time, otherwise it's |
|
|
2001 | the timeout value currently configured. |
|
|
2002 | |
|
|
2003 | That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns |
|
|
2004 | C<5>. When the timer is started and one second passes, C<ev_timer_remaining> |
|
|
2005 | will return C<4>. When the timer expires and is restarted, it will return |
|
|
2006 | roughly C<7> (likely slightly less as callback invocation takes some time, |
|
|
2007 | too), and so on. |
1531 | |
2008 | |
1532 | =item ev_tstamp repeat [read-write] |
2009 | =item ev_tstamp repeat [read-write] |
1533 | |
2010 | |
1534 | The current C<repeat> value. Will be used each time the watcher times out |
2011 | The current C<repeat> value. Will be used each time the watcher times out |
1535 | or C<ev_timer_again> is called, and determines the next timeout (if any), |
2012 | or C<ev_timer_again> is called, and determines the next timeout (if any), |
… | |
… | |
1561 | } |
2038 | } |
1562 | |
2039 | |
1563 | ev_timer mytimer; |
2040 | ev_timer mytimer; |
1564 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
2041 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1565 | ev_timer_again (&mytimer); /* start timer */ |
2042 | ev_timer_again (&mytimer); /* start timer */ |
1566 | ev_loop (loop, 0); |
2043 | ev_run (loop, 0); |
1567 | |
2044 | |
1568 | // and in some piece of code that gets executed on any "activity": |
2045 | // and in some piece of code that gets executed on any "activity": |
1569 | // reset the timeout to start ticking again at 10 seconds |
2046 | // reset the timeout to start ticking again at 10 seconds |
1570 | ev_timer_again (&mytimer); |
2047 | ev_timer_again (&mytimer); |
1571 | |
2048 | |
… | |
… | |
1573 | =head2 C<ev_periodic> - to cron or not to cron? |
2050 | =head2 C<ev_periodic> - to cron or not to cron? |
1574 | |
2051 | |
1575 | Periodic watchers are also timers of a kind, but they are very versatile |
2052 | Periodic watchers are also timers of a kind, but they are very versatile |
1576 | (and unfortunately a bit complex). |
2053 | (and unfortunately a bit complex). |
1577 | |
2054 | |
1578 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
2055 | Unlike C<ev_timer>, periodic watchers are not based on real time (or |
1579 | but on wall clock time (absolute time). You can tell a periodic watcher |
2056 | relative time, the physical time that passes) but on wall clock time |
1580 | to trigger after some specific point in time. For example, if you tell a |
2057 | (absolute time, the thing you can read on your calender or clock). The |
1581 | periodic watcher to trigger in 10 seconds (by specifying e.g. C<ev_now () |
2058 | difference is that wall clock time can run faster or slower than real |
1582 | + 10.>, that is, an absolute time not a delay) and then reset your system |
2059 | time, and time jumps are not uncommon (e.g. when you adjust your |
1583 | clock to January of the previous year, then it will take more than year |
2060 | wrist-watch). |
1584 | to trigger the event (unlike an C<ev_timer>, which would still trigger |
|
|
1585 | roughly 10 seconds later as it uses a relative timeout). |
|
|
1586 | |
2061 | |
|
|
2062 | You can tell a periodic watcher to trigger after some specific point |
|
|
2063 | in time: for example, if you tell a periodic watcher to trigger "in 10 |
|
|
2064 | seconds" (by specifying e.g. C<ev_now () + 10.>, that is, an absolute time |
|
|
2065 | not a delay) and then reset your system clock to January of the previous |
|
|
2066 | year, then it will take a year or more to trigger the event (unlike an |
|
|
2067 | C<ev_timer>, which would still trigger roughly 10 seconds after starting |
|
|
2068 | it, as it uses a relative timeout). |
|
|
2069 | |
1587 | C<ev_periodic>s can also be used to implement vastly more complex timers, |
2070 | C<ev_periodic> watchers can also be used to implement vastly more complex |
1588 | such as triggering an event on each "midnight, local time", or other |
2071 | timers, such as triggering an event on each "midnight, local time", or |
1589 | complicated rules. |
2072 | other complicated rules. This cannot be done with C<ev_timer> watchers, as |
|
|
2073 | those cannot react to time jumps. |
1590 | |
2074 | |
1591 | As with timers, the callback is guaranteed to be invoked only when the |
2075 | As with timers, the callback is guaranteed to be invoked only when the |
1592 | time (C<at>) has passed, but if multiple periodic timers become ready |
2076 | point in time where it is supposed to trigger has passed. If multiple |
1593 | during the same loop iteration, then order of execution is undefined. |
2077 | timers become ready during the same loop iteration then the ones with |
|
|
2078 | earlier time-out values are invoked before ones with later time-out values |
|
|
2079 | (but this is no longer true when a callback calls C<ev_run> recursively). |
1594 | |
2080 | |
1595 | =head3 Watcher-Specific Functions and Data Members |
2081 | =head3 Watcher-Specific Functions and Data Members |
1596 | |
2082 | |
1597 | =over 4 |
2083 | =over 4 |
1598 | |
2084 | |
1599 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
2085 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp offset, ev_tstamp interval, reschedule_cb) |
1600 | |
2086 | |
1601 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
2087 | =item ev_periodic_set (ev_periodic *, ev_tstamp offset, ev_tstamp interval, reschedule_cb) |
1602 | |
2088 | |
1603 | Lots of arguments, lets sort it out... There are basically three modes of |
2089 | Lots of arguments, let's sort it out... There are basically three modes of |
1604 | operation, and we will explain them from simplest to most complex: |
2090 | operation, and we will explain them from simplest to most complex: |
1605 | |
2091 | |
1606 | =over 4 |
2092 | =over 4 |
1607 | |
2093 | |
1608 | =item * absolute timer (at = time, interval = reschedule_cb = 0) |
2094 | =item * absolute timer (offset = absolute time, interval = 0, reschedule_cb = 0) |
1609 | |
2095 | |
1610 | In this configuration the watcher triggers an event after the wall clock |
2096 | In this configuration the watcher triggers an event after the wall clock |
1611 | time C<at> has passed. It will not repeat and will not adjust when a time |
2097 | time C<offset> has passed. It will not repeat and will not adjust when a |
1612 | jump occurs, that is, if it is to be run at January 1st 2011 then it will |
2098 | time jump occurs, that is, if it is to be run at January 1st 2011 then it |
1613 | only run when the system clock reaches or surpasses this time. |
2099 | will be stopped and invoked when the system clock reaches or surpasses |
|
|
2100 | this point in time. |
1614 | |
2101 | |
1615 | =item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
2102 | =item * repeating interval timer (offset = offset within interval, interval > 0, reschedule_cb = 0) |
1616 | |
2103 | |
1617 | In this mode the watcher will always be scheduled to time out at the next |
2104 | In this mode the watcher will always be scheduled to time out at the next |
1618 | C<at + N * interval> time (for some integer N, which can also be negative) |
2105 | C<offset + N * interval> time (for some integer N, which can also be |
1619 | and then repeat, regardless of any time jumps. |
2106 | negative) and then repeat, regardless of any time jumps. The C<offset> |
|
|
2107 | argument is merely an offset into the C<interval> periods. |
1620 | |
2108 | |
1621 | This can be used to create timers that do not drift with respect to the |
2109 | This can be used to create timers that do not drift with respect to the |
1622 | system clock, for example, here is a C<ev_periodic> that triggers each |
2110 | system clock, for example, here is an C<ev_periodic> that triggers each |
1623 | hour, on the hour: |
2111 | hour, on the hour (with respect to UTC): |
1624 | |
2112 | |
1625 | ev_periodic_set (&periodic, 0., 3600., 0); |
2113 | ev_periodic_set (&periodic, 0., 3600., 0); |
1626 | |
2114 | |
1627 | This doesn't mean there will always be 3600 seconds in between triggers, |
2115 | This doesn't mean there will always be 3600 seconds in between triggers, |
1628 | but only that the callback will be called when the system time shows a |
2116 | but only that the callback will be called when the system time shows a |
1629 | full hour (UTC), or more correctly, when the system time is evenly divisible |
2117 | full hour (UTC), or more correctly, when the system time is evenly divisible |
1630 | by 3600. |
2118 | by 3600. |
1631 | |
2119 | |
1632 | Another way to think about it (for the mathematically inclined) is that |
2120 | Another way to think about it (for the mathematically inclined) is that |
1633 | C<ev_periodic> will try to run the callback in this mode at the next possible |
2121 | C<ev_periodic> will try to run the callback in this mode at the next possible |
1634 | time where C<time = at (mod interval)>, regardless of any time jumps. |
2122 | time where C<time = offset (mod interval)>, regardless of any time jumps. |
1635 | |
2123 | |
1636 | For numerical stability it is preferable that the C<at> value is near |
2124 | For numerical stability it is preferable that the C<offset> value is near |
1637 | C<ev_now ()> (the current time), but there is no range requirement for |
2125 | C<ev_now ()> (the current time), but there is no range requirement for |
1638 | this value, and in fact is often specified as zero. |
2126 | this value, and in fact is often specified as zero. |
1639 | |
2127 | |
1640 | Note also that there is an upper limit to how often a timer can fire (CPU |
2128 | Note also that there is an upper limit to how often a timer can fire (CPU |
1641 | speed for example), so if C<interval> is very small then timing stability |
2129 | speed for example), so if C<interval> is very small then timing stability |
1642 | will of course deteriorate. Libev itself tries to be exact to be about one |
2130 | will of course deteriorate. Libev itself tries to be exact to be about one |
1643 | millisecond (if the OS supports it and the machine is fast enough). |
2131 | millisecond (if the OS supports it and the machine is fast enough). |
1644 | |
2132 | |
1645 | =item * manual reschedule mode (at and interval ignored, reschedule_cb = callback) |
2133 | =item * manual reschedule mode (offset ignored, interval ignored, reschedule_cb = callback) |
1646 | |
2134 | |
1647 | In this mode the values for C<interval> and C<at> are both being |
2135 | In this mode the values for C<interval> and C<offset> are both being |
1648 | ignored. Instead, each time the periodic watcher gets scheduled, the |
2136 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1649 | reschedule callback will be called with the watcher as first, and the |
2137 | reschedule callback will be called with the watcher as first, and the |
1650 | current time as second argument. |
2138 | current time as second argument. |
1651 | |
2139 | |
1652 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
2140 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, ever, |
1653 | ever, or make ANY event loop modifications whatsoever>. |
2141 | or make ANY other event loop modifications whatsoever, unless explicitly |
|
|
2142 | allowed by documentation here>. |
1654 | |
2143 | |
1655 | If you need to stop it, return C<now + 1e30> (or so, fudge fudge) and stop |
2144 | If you need to stop it, return C<now + 1e30> (or so, fudge fudge) and stop |
1656 | it afterwards (e.g. by starting an C<ev_prepare> watcher, which is the |
2145 | it afterwards (e.g. by starting an C<ev_prepare> watcher, which is the |
1657 | only event loop modification you are allowed to do). |
2146 | only event loop modification you are allowed to do). |
1658 | |
2147 | |
… | |
… | |
1688 | a different time than the last time it was called (e.g. in a crond like |
2177 | a different time than the last time it was called (e.g. in a crond like |
1689 | program when the crontabs have changed). |
2178 | program when the crontabs have changed). |
1690 | |
2179 | |
1691 | =item ev_tstamp ev_periodic_at (ev_periodic *) |
2180 | =item ev_tstamp ev_periodic_at (ev_periodic *) |
1692 | |
2181 | |
1693 | When active, returns the absolute time that the watcher is supposed to |
2182 | When active, returns the absolute time that the watcher is supposed |
1694 | trigger next. |
2183 | to trigger next. This is not the same as the C<offset> argument to |
|
|
2184 | C<ev_periodic_set>, but indeed works even in interval and manual |
|
|
2185 | rescheduling modes. |
1695 | |
2186 | |
1696 | =item ev_tstamp offset [read-write] |
2187 | =item ev_tstamp offset [read-write] |
1697 | |
2188 | |
1698 | When repeating, this contains the offset value, otherwise this is the |
2189 | When repeating, this contains the offset value, otherwise this is the |
1699 | absolute point in time (the C<at> value passed to C<ev_periodic_set>). |
2190 | absolute point in time (the C<offset> value passed to C<ev_periodic_set>, |
|
|
2191 | although libev might modify this value for better numerical stability). |
1700 | |
2192 | |
1701 | Can be modified any time, but changes only take effect when the periodic |
2193 | Can be modified any time, but changes only take effect when the periodic |
1702 | timer fires or C<ev_periodic_again> is being called. |
2194 | timer fires or C<ev_periodic_again> is being called. |
1703 | |
2195 | |
1704 | =item ev_tstamp interval [read-write] |
2196 | =item ev_tstamp interval [read-write] |
… | |
… | |
1720 | Example: Call a callback every hour, or, more precisely, whenever the |
2212 | Example: Call a callback every hour, or, more precisely, whenever the |
1721 | system time is divisible by 3600. The callback invocation times have |
2213 | system time is divisible by 3600. The callback invocation times have |
1722 | potentially a lot of jitter, but good long-term stability. |
2214 | potentially a lot of jitter, but good long-term stability. |
1723 | |
2215 | |
1724 | static void |
2216 | static void |
1725 | clock_cb (struct ev_loop *loop, ev_io *w, int revents) |
2217 | clock_cb (struct ev_loop *loop, ev_periodic *w, int revents) |
1726 | { |
2218 | { |
1727 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
2219 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
1728 | } |
2220 | } |
1729 | |
2221 | |
1730 | ev_periodic hourly_tick; |
2222 | ev_periodic hourly_tick; |
… | |
… | |
1756 | Signal watchers will trigger an event when the process receives a specific |
2248 | Signal watchers will trigger an event when the process receives a specific |
1757 | signal one or more times. Even though signals are very asynchronous, libev |
2249 | signal one or more times. Even though signals are very asynchronous, libev |
1758 | will try it's best to deliver signals synchronously, i.e. as part of the |
2250 | will try it's best to deliver signals synchronously, i.e. as part of the |
1759 | normal event processing, like any other event. |
2251 | normal event processing, like any other event. |
1760 | |
2252 | |
1761 | If you want signals asynchronously, just use C<sigaction> as you would |
2253 | If you want signals to be delivered truly asynchronously, just use |
1762 | do without libev and forget about sharing the signal. You can even use |
2254 | C<sigaction> as you would do without libev and forget about sharing |
1763 | C<ev_async> from a signal handler to synchronously wake up an event loop. |
2255 | the signal. You can even use C<ev_async> from a signal handler to |
|
|
2256 | synchronously wake up an event loop. |
1764 | |
2257 | |
1765 | You can configure as many watchers as you like per signal. Only when the |
2258 | You can configure as many watchers as you like for the same signal, but |
|
|
2259 | only within the same loop, i.e. you can watch for C<SIGINT> in your |
|
|
2260 | default loop and for C<SIGIO> in another loop, but you cannot watch for |
|
|
2261 | C<SIGINT> in both the default loop and another loop at the same time. At |
|
|
2262 | the moment, C<SIGCHLD> is permanently tied to the default loop. |
|
|
2263 | |
1766 | first watcher gets started will libev actually register a signal handler |
2264 | When the first watcher gets started will libev actually register something |
1767 | with the kernel (thus it coexists with your own signal handlers as long as |
2265 | with the kernel (thus it coexists with your own signal handlers as long as |
1768 | you don't register any with libev for the same signal). Similarly, when |
2266 | you don't register any with libev for the same signal). |
1769 | the last signal watcher for a signal is stopped, libev will reset the |
|
|
1770 | signal handler to SIG_DFL (regardless of what it was set to before). |
|
|
1771 | |
2267 | |
1772 | If possible and supported, libev will install its handlers with |
2268 | If possible and supported, libev will install its handlers with |
1773 | C<SA_RESTART> behaviour enabled, so system calls should not be unduly |
2269 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
1774 | interrupted. If you have a problem with system calls getting interrupted by |
2270 | not be unduly interrupted. If you have a problem with system calls getting |
1775 | signals you can block all signals in an C<ev_check> watcher and unblock |
2271 | interrupted by signals you can block all signals in an C<ev_check> watcher |
1776 | them in an C<ev_prepare> watcher. |
2272 | and unblock them in an C<ev_prepare> watcher. |
|
|
2273 | |
|
|
2274 | =head3 The special problem of inheritance over fork/execve/pthread_create |
|
|
2275 | |
|
|
2276 | Both the signal mask (C<sigprocmask>) and the signal disposition |
|
|
2277 | (C<sigaction>) are unspecified after starting a signal watcher (and after |
|
|
2278 | stopping it again), that is, libev might or might not block the signal, |
|
|
2279 | and might or might not set or restore the installed signal handler. |
|
|
2280 | |
|
|
2281 | While this does not matter for the signal disposition (libev never |
|
|
2282 | sets signals to C<SIG_IGN>, so handlers will be reset to C<SIG_DFL> on |
|
|
2283 | C<execve>), this matters for the signal mask: many programs do not expect |
|
|
2284 | certain signals to be blocked. |
|
|
2285 | |
|
|
2286 | This means that before calling C<exec> (from the child) you should reset |
|
|
2287 | the signal mask to whatever "default" you expect (all clear is a good |
|
|
2288 | choice usually). |
|
|
2289 | |
|
|
2290 | The simplest way to ensure that the signal mask is reset in the child is |
|
|
2291 | to install a fork handler with C<pthread_atfork> that resets it. That will |
|
|
2292 | catch fork calls done by libraries (such as the libc) as well. |
|
|
2293 | |
|
|
2294 | In current versions of libev, the signal will not be blocked indefinitely |
|
|
2295 | unless you use the C<signalfd> API (C<EV_SIGNALFD>). While this reduces |
|
|
2296 | the window of opportunity for problems, it will not go away, as libev |
|
|
2297 | I<has> to modify the signal mask, at least temporarily. |
|
|
2298 | |
|
|
2299 | So I can't stress this enough: I<If you do not reset your signal mask when |
|
|
2300 | you expect it to be empty, you have a race condition in your code>. This |
|
|
2301 | is not a libev-specific thing, this is true for most event libraries. |
1777 | |
2302 | |
1778 | =head3 Watcher-Specific Functions and Data Members |
2303 | =head3 Watcher-Specific Functions and Data Members |
1779 | |
2304 | |
1780 | =over 4 |
2305 | =over 4 |
1781 | |
2306 | |
… | |
… | |
1797 | Example: Try to exit cleanly on SIGINT. |
2322 | Example: Try to exit cleanly on SIGINT. |
1798 | |
2323 | |
1799 | static void |
2324 | static void |
1800 | sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2325 | sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
1801 | { |
2326 | { |
1802 | ev_unloop (loop, EVUNLOOP_ALL); |
2327 | ev_break (loop, EVBREAK_ALL); |
1803 | } |
2328 | } |
1804 | |
2329 | |
1805 | ev_signal signal_watcher; |
2330 | ev_signal signal_watcher; |
1806 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
2331 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1807 | ev_signal_start (loop, &signal_watcher); |
2332 | ev_signal_start (loop, &signal_watcher); |
… | |
… | |
1813 | some child status changes (most typically when a child of yours dies or |
2338 | some child status changes (most typically when a child of yours dies or |
1814 | exits). It is permissible to install a child watcher I<after> the child |
2339 | exits). It is permissible to install a child watcher I<after> the child |
1815 | has been forked (which implies it might have already exited), as long |
2340 | has been forked (which implies it might have already exited), as long |
1816 | as the event loop isn't entered (or is continued from a watcher), i.e., |
2341 | as the event loop isn't entered (or is continued from a watcher), i.e., |
1817 | forking and then immediately registering a watcher for the child is fine, |
2342 | forking and then immediately registering a watcher for the child is fine, |
1818 | but forking and registering a watcher a few event loop iterations later is |
2343 | but forking and registering a watcher a few event loop iterations later or |
1819 | not. |
2344 | in the next callback invocation is not. |
1820 | |
2345 | |
1821 | Only the default event loop is capable of handling signals, and therefore |
2346 | Only the default event loop is capable of handling signals, and therefore |
1822 | you can only register child watchers in the default event loop. |
2347 | you can only register child watchers in the default event loop. |
1823 | |
2348 | |
|
|
2349 | Due to some design glitches inside libev, child watchers will always be |
|
|
2350 | handled at maximum priority (their priority is set to C<EV_MAXPRI> by |
|
|
2351 | libev) |
|
|
2352 | |
1824 | =head3 Process Interaction |
2353 | =head3 Process Interaction |
1825 | |
2354 | |
1826 | Libev grabs C<SIGCHLD> as soon as the default event loop is |
2355 | Libev grabs C<SIGCHLD> as soon as the default event loop is |
1827 | initialised. This is necessary to guarantee proper behaviour even if |
2356 | initialised. This is necessary to guarantee proper behaviour even if the |
1828 | the first child watcher is started after the child exits. The occurrence |
2357 | first child watcher is started after the child exits. The occurrence |
1829 | of C<SIGCHLD> is recorded asynchronously, but child reaping is done |
2358 | of C<SIGCHLD> is recorded asynchronously, but child reaping is done |
1830 | synchronously as part of the event loop processing. Libev always reaps all |
2359 | synchronously as part of the event loop processing. Libev always reaps all |
1831 | children, even ones not watched. |
2360 | children, even ones not watched. |
1832 | |
2361 | |
1833 | =head3 Overriding the Built-In Processing |
2362 | =head3 Overriding the Built-In Processing |
… | |
… | |
1843 | =head3 Stopping the Child Watcher |
2372 | =head3 Stopping the Child Watcher |
1844 | |
2373 | |
1845 | Currently, the child watcher never gets stopped, even when the |
2374 | Currently, the child watcher never gets stopped, even when the |
1846 | child terminates, so normally one needs to stop the watcher in the |
2375 | child terminates, so normally one needs to stop the watcher in the |
1847 | callback. Future versions of libev might stop the watcher automatically |
2376 | callback. Future versions of libev might stop the watcher automatically |
1848 | when a child exit is detected. |
2377 | when a child exit is detected (calling C<ev_child_stop> twice is not a |
|
|
2378 | problem). |
1849 | |
2379 | |
1850 | =head3 Watcher-Specific Functions and Data Members |
2380 | =head3 Watcher-Specific Functions and Data Members |
1851 | |
2381 | |
1852 | =over 4 |
2382 | =over 4 |
1853 | |
2383 | |
… | |
… | |
1910 | |
2440 | |
1911 | |
2441 | |
1912 | =head2 C<ev_stat> - did the file attributes just change? |
2442 | =head2 C<ev_stat> - did the file attributes just change? |
1913 | |
2443 | |
1914 | This watches a file system path for attribute changes. That is, it calls |
2444 | This watches a file system path for attribute changes. That is, it calls |
1915 | C<stat> regularly (or when the OS says it changed) and sees if it changed |
2445 | C<stat> on that path in regular intervals (or when the OS says it changed) |
1916 | compared to the last time, invoking the callback if it did. |
2446 | and sees if it changed compared to the last time, invoking the callback if |
|
|
2447 | it did. |
1917 | |
2448 | |
1918 | The path does not need to exist: changing from "path exists" to "path does |
2449 | The path does not need to exist: changing from "path exists" to "path does |
1919 | not exist" is a status change like any other. The condition "path does |
2450 | not exist" is a status change like any other. The condition "path does not |
1920 | not exist" is signified by the C<st_nlink> field being zero (which is |
2451 | exist" (or more correctly "path cannot be stat'ed") is signified by the |
1921 | otherwise always forced to be at least one) and all the other fields of |
2452 | C<st_nlink> field being zero (which is otherwise always forced to be at |
1922 | the stat buffer having unspecified contents. |
2453 | least one) and all the other fields of the stat buffer having unspecified |
|
|
2454 | contents. |
1923 | |
2455 | |
1924 | The path I<should> be absolute and I<must not> end in a slash. If it is |
2456 | The path I<must not> end in a slash or contain special components such as |
|
|
2457 | C<.> or C<..>. The path I<should> be absolute: If it is relative and |
1925 | relative and your working directory changes, the behaviour is undefined. |
2458 | your working directory changes, then the behaviour is undefined. |
1926 | |
2459 | |
1927 | Since there is no standard kernel interface to do this, the portable |
2460 | Since there is no portable change notification interface available, the |
1928 | implementation simply calls C<stat (2)> regularly on the path to see if |
2461 | portable implementation simply calls C<stat(2)> regularly on the path |
1929 | it changed somehow. You can specify a recommended polling interval for |
2462 | to see if it changed somehow. You can specify a recommended polling |
1930 | this case. If you specify a polling interval of C<0> (highly recommended!) |
2463 | interval for this case. If you specify a polling interval of C<0> (highly |
1931 | then a I<suitable, unspecified default> value will be used (which |
2464 | recommended!) then a I<suitable, unspecified default> value will be used |
1932 | you can expect to be around five seconds, although this might change |
2465 | (which you can expect to be around five seconds, although this might |
1933 | dynamically). Libev will also impose a minimum interval which is currently |
2466 | change dynamically). Libev will also impose a minimum interval which is |
1934 | around C<0.1>, but thats usually overkill. |
2467 | currently around C<0.1>, but that's usually overkill. |
1935 | |
2468 | |
1936 | This watcher type is not meant for massive numbers of stat watchers, |
2469 | This watcher type is not meant for massive numbers of stat watchers, |
1937 | as even with OS-supported change notifications, this can be |
2470 | as even with OS-supported change notifications, this can be |
1938 | resource-intensive. |
2471 | resource-intensive. |
1939 | |
2472 | |
1940 | At the time of this writing, the only OS-specific interface implemented |
2473 | At the time of this writing, the only OS-specific interface implemented |
1941 | is the Linux inotify interface (implementing kqueue support is left as |
2474 | is the Linux inotify interface (implementing kqueue support is left as an |
1942 | an exercise for the reader. Note, however, that the author sees no way |
2475 | exercise for the reader. Note, however, that the author sees no way of |
1943 | of implementing C<ev_stat> semantics with kqueue). |
2476 | implementing C<ev_stat> semantics with kqueue, except as a hint). |
1944 | |
2477 | |
1945 | =head3 ABI Issues (Largefile Support) |
2478 | =head3 ABI Issues (Largefile Support) |
1946 | |
2479 | |
1947 | Libev by default (unless the user overrides this) uses the default |
2480 | Libev by default (unless the user overrides this) uses the default |
1948 | compilation environment, which means that on systems with large file |
2481 | compilation environment, which means that on systems with large file |
1949 | support disabled by default, you get the 32 bit version of the stat |
2482 | support disabled by default, you get the 32 bit version of the stat |
1950 | structure. When using the library from programs that change the ABI to |
2483 | structure. When using the library from programs that change the ABI to |
1951 | use 64 bit file offsets the programs will fail. In that case you have to |
2484 | use 64 bit file offsets the programs will fail. In that case you have to |
1952 | compile libev with the same flags to get binary compatibility. This is |
2485 | compile libev with the same flags to get binary compatibility. This is |
1953 | obviously the case with any flags that change the ABI, but the problem is |
2486 | obviously the case with any flags that change the ABI, but the problem is |
1954 | most noticeably disabled with ev_stat and large file support. |
2487 | most noticeably displayed with ev_stat and large file support. |
1955 | |
2488 | |
1956 | The solution for this is to lobby your distribution maker to make large |
2489 | The solution for this is to lobby your distribution maker to make large |
1957 | file interfaces available by default (as e.g. FreeBSD does) and not |
2490 | file interfaces available by default (as e.g. FreeBSD does) and not |
1958 | optional. Libev cannot simply switch on large file support because it has |
2491 | optional. Libev cannot simply switch on large file support because it has |
1959 | to exchange stat structures with application programs compiled using the |
2492 | to exchange stat structures with application programs compiled using the |
1960 | default compilation environment. |
2493 | default compilation environment. |
1961 | |
2494 | |
1962 | =head3 Inotify and Kqueue |
2495 | =head3 Inotify and Kqueue |
1963 | |
2496 | |
1964 | When C<inotify (7)> support has been compiled into libev (generally |
2497 | When C<inotify (7)> support has been compiled into libev and present at |
1965 | only available with Linux 2.6.25 or above due to bugs in earlier |
2498 | runtime, it will be used to speed up change detection where possible. The |
1966 | implementations) and present at runtime, it will be used to speed up |
2499 | inotify descriptor will be created lazily when the first C<ev_stat> |
1967 | change detection where possible. The inotify descriptor will be created |
2500 | watcher is being started. |
1968 | lazily when the first C<ev_stat> watcher is being started. |
|
|
1969 | |
2501 | |
1970 | Inotify presence does not change the semantics of C<ev_stat> watchers |
2502 | Inotify presence does not change the semantics of C<ev_stat> watchers |
1971 | except that changes might be detected earlier, and in some cases, to avoid |
2503 | except that changes might be detected earlier, and in some cases, to avoid |
1972 | making regular C<stat> calls. Even in the presence of inotify support |
2504 | making regular C<stat> calls. Even in the presence of inotify support |
1973 | there are many cases where libev has to resort to regular C<stat> polling, |
2505 | there are many cases where libev has to resort to regular C<stat> polling, |
1974 | but as long as the path exists, libev usually gets away without polling. |
2506 | but as long as kernel 2.6.25 or newer is used (2.6.24 and older have too |
|
|
2507 | many bugs), the path exists (i.e. stat succeeds), and the path resides on |
|
|
2508 | a local filesystem (libev currently assumes only ext2/3, jfs, reiserfs and |
|
|
2509 | xfs are fully working) libev usually gets away without polling. |
1975 | |
2510 | |
1976 | There is no support for kqueue, as apparently it cannot be used to |
2511 | There is no support for kqueue, as apparently it cannot be used to |
1977 | implement this functionality, due to the requirement of having a file |
2512 | implement this functionality, due to the requirement of having a file |
1978 | descriptor open on the object at all times, and detecting renames, unlinks |
2513 | descriptor open on the object at all times, and detecting renames, unlinks |
1979 | etc. is difficult. |
2514 | etc. is difficult. |
1980 | |
2515 | |
|
|
2516 | =head3 C<stat ()> is a synchronous operation |
|
|
2517 | |
|
|
2518 | Libev doesn't normally do any kind of I/O itself, and so is not blocking |
|
|
2519 | the process. The exception are C<ev_stat> watchers - those call C<stat |
|
|
2520 | ()>, which is a synchronous operation. |
|
|
2521 | |
|
|
2522 | For local paths, this usually doesn't matter: unless the system is very |
|
|
2523 | busy or the intervals between stat's are large, a stat call will be fast, |
|
|
2524 | as the path data is usually in memory already (except when starting the |
|
|
2525 | watcher). |
|
|
2526 | |
|
|
2527 | For networked file systems, calling C<stat ()> can block an indefinite |
|
|
2528 | time due to network issues, and even under good conditions, a stat call |
|
|
2529 | often takes multiple milliseconds. |
|
|
2530 | |
|
|
2531 | Therefore, it is best to avoid using C<ev_stat> watchers on networked |
|
|
2532 | paths, although this is fully supported by libev. |
|
|
2533 | |
1981 | =head3 The special problem of stat time resolution |
2534 | =head3 The special problem of stat time resolution |
1982 | |
2535 | |
1983 | The C<stat ()> system call only supports full-second resolution portably, and |
2536 | The C<stat ()> system call only supports full-second resolution portably, |
1984 | even on systems where the resolution is higher, most file systems still |
2537 | and even on systems where the resolution is higher, most file systems |
1985 | only support whole seconds. |
2538 | still only support whole seconds. |
1986 | |
2539 | |
1987 | That means that, if the time is the only thing that changes, you can |
2540 | That means that, if the time is the only thing that changes, you can |
1988 | easily miss updates: on the first update, C<ev_stat> detects a change and |
2541 | easily miss updates: on the first update, C<ev_stat> detects a change and |
1989 | calls your callback, which does something. When there is another update |
2542 | calls your callback, which does something. When there is another update |
1990 | within the same second, C<ev_stat> will be unable to detect unless the |
2543 | within the same second, C<ev_stat> will be unable to detect unless the |
… | |
… | |
2133 | |
2686 | |
2134 | =head3 Watcher-Specific Functions and Data Members |
2687 | =head3 Watcher-Specific Functions and Data Members |
2135 | |
2688 | |
2136 | =over 4 |
2689 | =over 4 |
2137 | |
2690 | |
2138 | =item ev_idle_init (ev_signal *, callback) |
2691 | =item ev_idle_init (ev_idle *, callback) |
2139 | |
2692 | |
2140 | Initialises and configures the idle watcher - it has no parameters of any |
2693 | Initialises and configures the idle watcher - it has no parameters of any |
2141 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
2694 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
2142 | believe me. |
2695 | believe me. |
2143 | |
2696 | |
… | |
… | |
2156 | // no longer anything immediate to do. |
2709 | // no longer anything immediate to do. |
2157 | } |
2710 | } |
2158 | |
2711 | |
2159 | ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
2712 | ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
2160 | ev_idle_init (idle_watcher, idle_cb); |
2713 | ev_idle_init (idle_watcher, idle_cb); |
2161 | ev_idle_start (loop, idle_cb); |
2714 | ev_idle_start (loop, idle_watcher); |
2162 | |
2715 | |
2163 | |
2716 | |
2164 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
2717 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
2165 | |
2718 | |
2166 | Prepare and check watchers are usually (but not always) used in pairs: |
2719 | Prepare and check watchers are usually (but not always) used in pairs: |
2167 | prepare watchers get invoked before the process blocks and check watchers |
2720 | prepare watchers get invoked before the process blocks and check watchers |
2168 | afterwards. |
2721 | afterwards. |
2169 | |
2722 | |
2170 | You I<must not> call C<ev_loop> or similar functions that enter |
2723 | You I<must not> call C<ev_run> or similar functions that enter |
2171 | the current event loop from either C<ev_prepare> or C<ev_check> |
2724 | the current event loop from either C<ev_prepare> or C<ev_check> |
2172 | watchers. Other loops than the current one are fine, however. The |
2725 | watchers. Other loops than the current one are fine, however. The |
2173 | rationale behind this is that you do not need to check for recursion in |
2726 | rationale behind this is that you do not need to check for recursion in |
2174 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
2727 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
2175 | C<ev_check> so if you have one watcher of each kind they will always be |
2728 | C<ev_check> so if you have one watcher of each kind they will always be |
… | |
… | |
2259 | struct pollfd fds [nfd]; |
2812 | struct pollfd fds [nfd]; |
2260 | // actual code will need to loop here and realloc etc. |
2813 | // actual code will need to loop here and realloc etc. |
2261 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
2814 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
2262 | |
2815 | |
2263 | /* the callback is illegal, but won't be called as we stop during check */ |
2816 | /* the callback is illegal, but won't be called as we stop during check */ |
2264 | ev_timer_init (&tw, 0, timeout * 1e-3); |
2817 | ev_timer_init (&tw, 0, timeout * 1e-3, 0.); |
2265 | ev_timer_start (loop, &tw); |
2818 | ev_timer_start (loop, &tw); |
2266 | |
2819 | |
2267 | // create one ev_io per pollfd |
2820 | // create one ev_io per pollfd |
2268 | for (int i = 0; i < nfd; ++i) |
2821 | for (int i = 0; i < nfd; ++i) |
2269 | { |
2822 | { |
… | |
… | |
2343 | |
2896 | |
2344 | if (timeout >= 0) |
2897 | if (timeout >= 0) |
2345 | // create/start timer |
2898 | // create/start timer |
2346 | |
2899 | |
2347 | // poll |
2900 | // poll |
2348 | ev_loop (EV_A_ 0); |
2901 | ev_run (EV_A_ 0); |
2349 | |
2902 | |
2350 | // stop timer again |
2903 | // stop timer again |
2351 | if (timeout >= 0) |
2904 | if (timeout >= 0) |
2352 | ev_timer_stop (EV_A_ &to); |
2905 | ev_timer_stop (EV_A_ &to); |
2353 | |
2906 | |
… | |
… | |
2382 | some fds have to be watched and handled very quickly (with low latency), |
2935 | some fds have to be watched and handled very quickly (with low latency), |
2383 | and even priorities and idle watchers might have too much overhead. In |
2936 | and even priorities and idle watchers might have too much overhead. In |
2384 | this case you would put all the high priority stuff in one loop and all |
2937 | this case you would put all the high priority stuff in one loop and all |
2385 | the rest in a second one, and embed the second one in the first. |
2938 | the rest in a second one, and embed the second one in the first. |
2386 | |
2939 | |
2387 | As long as the watcher is active, the callback will be invoked every time |
2940 | As long as the watcher is active, the callback will be invoked every |
2388 | there might be events pending in the embedded loop. The callback must then |
2941 | time there might be events pending in the embedded loop. The callback |
2389 | call C<ev_embed_sweep (mainloop, watcher)> to make a single sweep and invoke |
2942 | must then call C<ev_embed_sweep (mainloop, watcher)> to make a single |
2390 | their callbacks (you could also start an idle watcher to give the embedded |
2943 | sweep and invoke their callbacks (the callback doesn't need to invoke the |
2391 | loop strictly lower priority for example). You can also set the callback |
2944 | C<ev_embed_sweep> function directly, it could also start an idle watcher |
2392 | to C<0>, in which case the embed watcher will automatically execute the |
2945 | to give the embedded loop strictly lower priority for example). |
2393 | embedded loop sweep. |
|
|
2394 | |
2946 | |
2395 | As long as the watcher is started it will automatically handle events. The |
2947 | You can also set the callback to C<0>, in which case the embed watcher |
2396 | callback will be invoked whenever some events have been handled. You can |
2948 | will automatically execute the embedded loop sweep whenever necessary. |
2397 | set the callback to C<0> to avoid having to specify one if you are not |
|
|
2398 | interested in that. |
|
|
2399 | |
2949 | |
2400 | Also, there have not currently been made special provisions for forking: |
2950 | Fork detection will be handled transparently while the C<ev_embed> watcher |
2401 | when you fork, you not only have to call C<ev_loop_fork> on both loops, |
2951 | is active, i.e., the embedded loop will automatically be forked when the |
2402 | but you will also have to stop and restart any C<ev_embed> watchers |
2952 | embedding loop forks. In other cases, the user is responsible for calling |
2403 | yourself - but you can use a fork watcher to handle this automatically, |
2953 | C<ev_loop_fork> on the embedded loop. |
2404 | and future versions of libev might do just that. |
|
|
2405 | |
2954 | |
2406 | Unfortunately, not all backends are embeddable: only the ones returned by |
2955 | Unfortunately, not all backends are embeddable: only the ones returned by |
2407 | C<ev_embeddable_backends> are, which, unfortunately, does not include any |
2956 | C<ev_embeddable_backends> are, which, unfortunately, does not include any |
2408 | portable one. |
2957 | portable one. |
2409 | |
2958 | |
… | |
… | |
2435 | if you do not want that, you need to temporarily stop the embed watcher). |
2984 | if you do not want that, you need to temporarily stop the embed watcher). |
2436 | |
2985 | |
2437 | =item ev_embed_sweep (loop, ev_embed *) |
2986 | =item ev_embed_sweep (loop, ev_embed *) |
2438 | |
2987 | |
2439 | Make a single, non-blocking sweep over the embedded loop. This works |
2988 | Make a single, non-blocking sweep over the embedded loop. This works |
2440 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
2989 | similarly to C<ev_run (embedded_loop, EVRUN_NOWAIT)>, but in the most |
2441 | appropriate way for embedded loops. |
2990 | appropriate way for embedded loops. |
2442 | |
2991 | |
2443 | =item struct ev_loop *other [read-only] |
2992 | =item struct ev_loop *other [read-only] |
2444 | |
2993 | |
2445 | The embedded event loop. |
2994 | The embedded event loop. |
… | |
… | |
2503 | event loop blocks next and before C<ev_check> watchers are being called, |
3052 | event loop blocks next and before C<ev_check> watchers are being called, |
2504 | and only in the child after the fork. If whoever good citizen calling |
3053 | and only in the child after the fork. If whoever good citizen calling |
2505 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
3054 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
2506 | handlers will be invoked, too, of course. |
3055 | handlers will be invoked, too, of course. |
2507 | |
3056 | |
|
|
3057 | =head3 The special problem of life after fork - how is it possible? |
|
|
3058 | |
|
|
3059 | Most uses of C<fork()> consist of forking, then some simple calls to set |
|
|
3060 | up/change the process environment, followed by a call to C<exec()>. This |
|
|
3061 | sequence should be handled by libev without any problems. |
|
|
3062 | |
|
|
3063 | This changes when the application actually wants to do event handling |
|
|
3064 | in the child, or both parent in child, in effect "continuing" after the |
|
|
3065 | fork. |
|
|
3066 | |
|
|
3067 | The default mode of operation (for libev, with application help to detect |
|
|
3068 | forks) is to duplicate all the state in the child, as would be expected |
|
|
3069 | when I<either> the parent I<or> the child process continues. |
|
|
3070 | |
|
|
3071 | When both processes want to continue using libev, then this is usually the |
|
|
3072 | wrong result. In that case, usually one process (typically the parent) is |
|
|
3073 | supposed to continue with all watchers in place as before, while the other |
|
|
3074 | process typically wants to start fresh, i.e. without any active watchers. |
|
|
3075 | |
|
|
3076 | The cleanest and most efficient way to achieve that with libev is to |
|
|
3077 | simply create a new event loop, which of course will be "empty", and |
|
|
3078 | use that for new watchers. This has the advantage of not touching more |
|
|
3079 | memory than necessary, and thus avoiding the copy-on-write, and the |
|
|
3080 | disadvantage of having to use multiple event loops (which do not support |
|
|
3081 | signal watchers). |
|
|
3082 | |
|
|
3083 | When this is not possible, or you want to use the default loop for |
|
|
3084 | other reasons, then in the process that wants to start "fresh", call |
|
|
3085 | C<ev_loop_destroy (EV_DEFAULT)> followed by C<ev_default_loop (...)>. |
|
|
3086 | Destroying the default loop will "orphan" (not stop) all registered |
|
|
3087 | watchers, so you have to be careful not to execute code that modifies |
|
|
3088 | those watchers. Note also that in that case, you have to re-register any |
|
|
3089 | signal watchers. |
|
|
3090 | |
2508 | =head3 Watcher-Specific Functions and Data Members |
3091 | =head3 Watcher-Specific Functions and Data Members |
2509 | |
3092 | |
2510 | =over 4 |
3093 | =over 4 |
2511 | |
3094 | |
2512 | =item ev_fork_init (ev_signal *, callback) |
3095 | =item ev_fork_init (ev_signal *, callback) |
… | |
… | |
2516 | believe me. |
3099 | believe me. |
2517 | |
3100 | |
2518 | =back |
3101 | =back |
2519 | |
3102 | |
2520 | |
3103 | |
2521 | =head2 C<ev_async> - how to wake up another event loop |
3104 | =head2 C<ev_async> - how to wake up an event loop |
2522 | |
3105 | |
2523 | In general, you cannot use an C<ev_loop> from multiple threads or other |
3106 | In general, you cannot use an C<ev_run> from multiple threads or other |
2524 | asynchronous sources such as signal handlers (as opposed to multiple event |
3107 | asynchronous sources such as signal handlers (as opposed to multiple event |
2525 | loops - those are of course safe to use in different threads). |
3108 | loops - those are of course safe to use in different threads). |
2526 | |
3109 | |
2527 | Sometimes, however, you need to wake up another event loop you do not |
3110 | Sometimes, however, you need to wake up an event loop you do not control, |
2528 | control, for example because it belongs to another thread. This is what |
3111 | for example because it belongs to another thread. This is what C<ev_async> |
2529 | C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you |
3112 | watchers do: as long as the C<ev_async> watcher is active, you can signal |
2530 | can signal it by calling C<ev_async_send>, which is thread- and signal |
3113 | it by calling C<ev_async_send>, which is thread- and signal safe. |
2531 | safe. |
|
|
2532 | |
3114 | |
2533 | This functionality is very similar to C<ev_signal> watchers, as signals, |
3115 | This functionality is very similar to C<ev_signal> watchers, as signals, |
2534 | too, are asynchronous in nature, and signals, too, will be compressed |
3116 | too, are asynchronous in nature, and signals, too, will be compressed |
2535 | (i.e. the number of callback invocations may be less than the number of |
3117 | (i.e. the number of callback invocations may be less than the number of |
2536 | C<ev_async_sent> calls). |
3118 | C<ev_async_sent> calls). |
… | |
… | |
2541 | =head3 Queueing |
3123 | =head3 Queueing |
2542 | |
3124 | |
2543 | C<ev_async> does not support queueing of data in any way. The reason |
3125 | C<ev_async> does not support queueing of data in any way. The reason |
2544 | is that the author does not know of a simple (or any) algorithm for a |
3126 | is that the author does not know of a simple (or any) algorithm for a |
2545 | multiple-writer-single-reader queue that works in all cases and doesn't |
3127 | multiple-writer-single-reader queue that works in all cases and doesn't |
2546 | need elaborate support such as pthreads. |
3128 | need elaborate support such as pthreads or unportable memory access |
|
|
3129 | semantics. |
2547 | |
3130 | |
2548 | That means that if you want to queue data, you have to provide your own |
3131 | That means that if you want to queue data, you have to provide your own |
2549 | queue. But at least I can tell you how to implement locking around your |
3132 | queue. But at least I can tell you how to implement locking around your |
2550 | queue: |
3133 | queue: |
2551 | |
3134 | |
… | |
… | |
2629 | =over 4 |
3212 | =over 4 |
2630 | |
3213 | |
2631 | =item ev_async_init (ev_async *, callback) |
3214 | =item ev_async_init (ev_async *, callback) |
2632 | |
3215 | |
2633 | Initialises and configures the async watcher - it has no parameters of any |
3216 | Initialises and configures the async watcher - it has no parameters of any |
2634 | kind. There is a C<ev_asynd_set> macro, but using it is utterly pointless, |
3217 | kind. There is a C<ev_async_set> macro, but using it is utterly pointless, |
2635 | trust me. |
3218 | trust me. |
2636 | |
3219 | |
2637 | =item ev_async_send (loop, ev_async *) |
3220 | =item ev_async_send (loop, ev_async *) |
2638 | |
3221 | |
2639 | Sends/signals/activates the given C<ev_async> watcher, that is, feeds |
3222 | Sends/signals/activates the given C<ev_async> watcher, that is, feeds |
2640 | an C<EV_ASYNC> event on the watcher into the event loop. Unlike |
3223 | an C<EV_ASYNC> event on the watcher into the event loop. Unlike |
2641 | C<ev_feed_event>, this call is safe to do from other threads, signal or |
3224 | C<ev_feed_event>, this call is safe to do from other threads, signal or |
2642 | similar contexts (see the discussion of C<EV_ATOMIC_T> in the embedding |
3225 | similar contexts (see the discussion of C<EV_ATOMIC_T> in the embedding |
2643 | section below on what exactly this means). |
3226 | section below on what exactly this means). |
2644 | |
3227 | |
|
|
3228 | Note that, as with other watchers in libev, multiple events might get |
|
|
3229 | compressed into a single callback invocation (another way to look at this |
|
|
3230 | is that C<ev_async> watchers are level-triggered, set on C<ev_async_send>, |
|
|
3231 | reset when the event loop detects that). |
|
|
3232 | |
2645 | This call incurs the overhead of a system call only once per loop iteration, |
3233 | This call incurs the overhead of a system call only once per event loop |
2646 | so while the overhead might be noticeable, it doesn't apply to repeated |
3234 | iteration, so while the overhead might be noticeable, it doesn't apply to |
2647 | calls to C<ev_async_send>. |
3235 | repeated calls to C<ev_async_send> for the same event loop. |
2648 | |
3236 | |
2649 | =item bool = ev_async_pending (ev_async *) |
3237 | =item bool = ev_async_pending (ev_async *) |
2650 | |
3238 | |
2651 | Returns a non-zero value when C<ev_async_send> has been called on the |
3239 | Returns a non-zero value when C<ev_async_send> has been called on the |
2652 | watcher but the event has not yet been processed (or even noted) by the |
3240 | watcher but the event has not yet been processed (or even noted) by the |
… | |
… | |
2655 | C<ev_async_send> sets a flag in the watcher and wakes up the loop. When |
3243 | C<ev_async_send> sets a flag in the watcher and wakes up the loop. When |
2656 | the loop iterates next and checks for the watcher to have become active, |
3244 | the loop iterates next and checks for the watcher to have become active, |
2657 | it will reset the flag again. C<ev_async_pending> can be used to very |
3245 | it will reset the flag again. C<ev_async_pending> can be used to very |
2658 | quickly check whether invoking the loop might be a good idea. |
3246 | quickly check whether invoking the loop might be a good idea. |
2659 | |
3247 | |
2660 | Not that this does I<not> check whether the watcher itself is pending, only |
3248 | Not that this does I<not> check whether the watcher itself is pending, |
2661 | whether it has been requested to make this watcher pending. |
3249 | only whether it has been requested to make this watcher pending: there |
|
|
3250 | is a time window between the event loop checking and resetting the async |
|
|
3251 | notification, and the callback being invoked. |
2662 | |
3252 | |
2663 | =back |
3253 | =back |
2664 | |
3254 | |
2665 | |
3255 | |
2666 | =head1 OTHER FUNCTIONS |
3256 | =head1 OTHER FUNCTIONS |
… | |
… | |
2683 | |
3273 | |
2684 | If C<timeout> is less than 0, then no timeout watcher will be |
3274 | If C<timeout> is less than 0, then no timeout watcher will be |
2685 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
3275 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
2686 | repeat = 0) will be started. C<0> is a valid timeout. |
3276 | repeat = 0) will be started. C<0> is a valid timeout. |
2687 | |
3277 | |
2688 | The callback has the type C<void (*cb)(int revents, void *arg)> and gets |
3278 | The callback has the type C<void (*cb)(int revents, void *arg)> and is |
2689 | passed an C<revents> set like normal event callbacks (a combination of |
3279 | passed an C<revents> set like normal event callbacks (a combination of |
2690 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg> |
3280 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMER>) and the C<arg> |
2691 | value passed to C<ev_once>. Note that it is possible to receive I<both> |
3281 | value passed to C<ev_once>. Note that it is possible to receive I<both> |
2692 | a timeout and an io event at the same time - you probably should give io |
3282 | a timeout and an io event at the same time - you probably should give io |
2693 | events precedence. |
3283 | events precedence. |
2694 | |
3284 | |
2695 | Example: wait up to ten seconds for data to appear on STDIN_FILENO. |
3285 | Example: wait up to ten seconds for data to appear on STDIN_FILENO. |
2696 | |
3286 | |
2697 | static void stdin_ready (int revents, void *arg) |
3287 | static void stdin_ready (int revents, void *arg) |
2698 | { |
3288 | { |
2699 | if (revents & EV_READ) |
3289 | if (revents & EV_READ) |
2700 | /* stdin might have data for us, joy! */; |
3290 | /* stdin might have data for us, joy! */; |
2701 | else if (revents & EV_TIMEOUT) |
3291 | else if (revents & EV_TIMER) |
2702 | /* doh, nothing entered */; |
3292 | /* doh, nothing entered */; |
2703 | } |
3293 | } |
2704 | |
3294 | |
2705 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3295 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
2706 | |
3296 | |
2707 | =item ev_feed_event (struct ev_loop *, watcher *, int revents) |
|
|
2708 | |
|
|
2709 | Feeds the given event set into the event loop, as if the specified event |
|
|
2710 | had happened for the specified watcher (which must be a pointer to an |
|
|
2711 | initialised but not necessarily started event watcher). |
|
|
2712 | |
|
|
2713 | =item ev_feed_fd_event (struct ev_loop *, int fd, int revents) |
3297 | =item ev_feed_fd_event (loop, int fd, int revents) |
2714 | |
3298 | |
2715 | Feed an event on the given fd, as if a file descriptor backend detected |
3299 | Feed an event on the given fd, as if a file descriptor backend detected |
2716 | the given events it. |
3300 | the given events it. |
2717 | |
3301 | |
2718 | =item ev_feed_signal_event (struct ev_loop *loop, int signum) |
3302 | =item ev_feed_signal_event (loop, int signum) |
2719 | |
3303 | |
2720 | Feed an event as if the given signal occurred (C<loop> must be the default |
3304 | Feed an event as if the given signal occurred (C<loop> must be the default |
2721 | loop!). |
3305 | loop!). |
2722 | |
3306 | |
2723 | =back |
3307 | =back |
… | |
… | |
2803 | |
3387 | |
2804 | =over 4 |
3388 | =over 4 |
2805 | |
3389 | |
2806 | =item ev::TYPE::TYPE () |
3390 | =item ev::TYPE::TYPE () |
2807 | |
3391 | |
2808 | =item ev::TYPE::TYPE (struct ev_loop *) |
3392 | =item ev::TYPE::TYPE (loop) |
2809 | |
3393 | |
2810 | =item ev::TYPE::~TYPE |
3394 | =item ev::TYPE::~TYPE |
2811 | |
3395 | |
2812 | The constructor (optionally) takes an event loop to associate the watcher |
3396 | The constructor (optionally) takes an event loop to associate the watcher |
2813 | with. If it is omitted, it will use C<EV_DEFAULT>. |
3397 | with. If it is omitted, it will use C<EV_DEFAULT>. |
… | |
… | |
2845 | |
3429 | |
2846 | myclass obj; |
3430 | myclass obj; |
2847 | ev::io iow; |
3431 | ev::io iow; |
2848 | iow.set <myclass, &myclass::io_cb> (&obj); |
3432 | iow.set <myclass, &myclass::io_cb> (&obj); |
2849 | |
3433 | |
|
|
3434 | =item w->set (object *) |
|
|
3435 | |
|
|
3436 | This is a variation of a method callback - leaving out the method to call |
|
|
3437 | will default the method to C<operator ()>, which makes it possible to use |
|
|
3438 | functor objects without having to manually specify the C<operator ()> all |
|
|
3439 | the time. Incidentally, you can then also leave out the template argument |
|
|
3440 | list. |
|
|
3441 | |
|
|
3442 | The C<operator ()> method prototype must be C<void operator ()(watcher &w, |
|
|
3443 | int revents)>. |
|
|
3444 | |
|
|
3445 | See the method-C<set> above for more details. |
|
|
3446 | |
|
|
3447 | Example: use a functor object as callback. |
|
|
3448 | |
|
|
3449 | struct myfunctor |
|
|
3450 | { |
|
|
3451 | void operator() (ev::io &w, int revents) |
|
|
3452 | { |
|
|
3453 | ... |
|
|
3454 | } |
|
|
3455 | } |
|
|
3456 | |
|
|
3457 | myfunctor f; |
|
|
3458 | |
|
|
3459 | ev::io w; |
|
|
3460 | w.set (&f); |
|
|
3461 | |
2850 | =item w->set<function> (void *data = 0) |
3462 | =item w->set<function> (void *data = 0) |
2851 | |
3463 | |
2852 | Also sets a callback, but uses a static method or plain function as |
3464 | Also sets a callback, but uses a static method or plain function as |
2853 | callback. The optional C<data> argument will be stored in the watcher's |
3465 | callback. The optional C<data> argument will be stored in the watcher's |
2854 | C<data> member and is free for you to use. |
3466 | C<data> member and is free for you to use. |
… | |
… | |
2860 | Example: Use a plain function as callback. |
3472 | Example: Use a plain function as callback. |
2861 | |
3473 | |
2862 | static void io_cb (ev::io &w, int revents) { } |
3474 | static void io_cb (ev::io &w, int revents) { } |
2863 | iow.set <io_cb> (); |
3475 | iow.set <io_cb> (); |
2864 | |
3476 | |
2865 | =item w->set (struct ev_loop *) |
3477 | =item w->set (loop) |
2866 | |
3478 | |
2867 | Associates a different C<struct ev_loop> with this watcher. You can only |
3479 | Associates a different C<struct ev_loop> with this watcher. You can only |
2868 | do this when the watcher is inactive (and not pending either). |
3480 | do this when the watcher is inactive (and not pending either). |
2869 | |
3481 | |
2870 | =item w->set ([arguments]) |
3482 | =item w->set ([arguments]) |
2871 | |
3483 | |
2872 | Basically the same as C<ev_TYPE_set>, with the same arguments. Must be |
3484 | Basically the same as C<ev_TYPE_set>, with the same arguments. Either this |
2873 | called at least once. Unlike the C counterpart, an active watcher gets |
3485 | method or a suitable start method must be called at least once. Unlike the |
2874 | automatically stopped and restarted when reconfiguring it with this |
3486 | C counterpart, an active watcher gets automatically stopped and restarted |
2875 | method. |
3487 | when reconfiguring it with this method. |
2876 | |
3488 | |
2877 | =item w->start () |
3489 | =item w->start () |
2878 | |
3490 | |
2879 | Starts the watcher. Note that there is no C<loop> argument, as the |
3491 | Starts the watcher. Note that there is no C<loop> argument, as the |
2880 | constructor already stores the event loop. |
3492 | constructor already stores the event loop. |
2881 | |
3493 | |
|
|
3494 | =item w->start ([arguments]) |
|
|
3495 | |
|
|
3496 | Instead of calling C<set> and C<start> methods separately, it is often |
|
|
3497 | convenient to wrap them in one call. Uses the same type of arguments as |
|
|
3498 | the configure C<set> method of the watcher. |
|
|
3499 | |
2882 | =item w->stop () |
3500 | =item w->stop () |
2883 | |
3501 | |
2884 | Stops the watcher if it is active. Again, no C<loop> argument. |
3502 | Stops the watcher if it is active. Again, no C<loop> argument. |
2885 | |
3503 | |
2886 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
3504 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
… | |
… | |
2898 | |
3516 | |
2899 | =back |
3517 | =back |
2900 | |
3518 | |
2901 | =back |
3519 | =back |
2902 | |
3520 | |
2903 | Example: Define a class with an IO and idle watcher, start one of them in |
3521 | Example: Define a class with two I/O and idle watchers, start the I/O |
2904 | the constructor. |
3522 | watchers in the constructor. |
2905 | |
3523 | |
2906 | class myclass |
3524 | class myclass |
2907 | { |
3525 | { |
2908 | ev::io io ; void io_cb (ev::io &w, int revents); |
3526 | ev::io io ; void io_cb (ev::io &w, int revents); |
|
|
3527 | ev::io2 io2 ; void io2_cb (ev::io &w, int revents); |
2909 | ev::idle idle; void idle_cb (ev::idle &w, int revents); |
3528 | ev::idle idle; void idle_cb (ev::idle &w, int revents); |
2910 | |
3529 | |
2911 | myclass (int fd) |
3530 | myclass (int fd) |
2912 | { |
3531 | { |
2913 | io .set <myclass, &myclass::io_cb > (this); |
3532 | io .set <myclass, &myclass::io_cb > (this); |
|
|
3533 | io2 .set <myclass, &myclass::io2_cb > (this); |
2914 | idle.set <myclass, &myclass::idle_cb> (this); |
3534 | idle.set <myclass, &myclass::idle_cb> (this); |
2915 | |
3535 | |
2916 | io.start (fd, ev::READ); |
3536 | io.set (fd, ev::WRITE); // configure the watcher |
|
|
3537 | io.start (); // start it whenever convenient |
|
|
3538 | |
|
|
3539 | io2.start (fd, ev::READ); // set + start in one call |
2917 | } |
3540 | } |
2918 | }; |
3541 | }; |
2919 | |
3542 | |
2920 | |
3543 | |
2921 | =head1 OTHER LANGUAGE BINDINGS |
3544 | =head1 OTHER LANGUAGE BINDINGS |
… | |
… | |
2940 | L<http://software.schmorp.de/pkg/EV>. |
3563 | L<http://software.schmorp.de/pkg/EV>. |
2941 | |
3564 | |
2942 | =item Python |
3565 | =item Python |
2943 | |
3566 | |
2944 | Python bindings can be found at L<http://code.google.com/p/pyev/>. It |
3567 | Python bindings can be found at L<http://code.google.com/p/pyev/>. It |
2945 | seems to be quite complete and well-documented. Note, however, that the |
3568 | seems to be quite complete and well-documented. |
2946 | patch they require for libev is outright dangerous as it breaks the ABI |
|
|
2947 | for everybody else, and therefore, should never be applied in an installed |
|
|
2948 | libev (if python requires an incompatible ABI then it needs to embed |
|
|
2949 | libev). |
|
|
2950 | |
3569 | |
2951 | =item Ruby |
3570 | =item Ruby |
2952 | |
3571 | |
2953 | Tony Arcieri has written a ruby extension that offers access to a subset |
3572 | Tony Arcieri has written a ruby extension that offers access to a subset |
2954 | of the libev API and adds file handle abstractions, asynchronous DNS and |
3573 | of the libev API and adds file handle abstractions, asynchronous DNS and |
2955 | more on top of it. It can be found via gem servers. Its homepage is at |
3574 | more on top of it. It can be found via gem servers. Its homepage is at |
2956 | L<http://rev.rubyforge.org/>. |
3575 | L<http://rev.rubyforge.org/>. |
2957 | |
3576 | |
|
|
3577 | Roger Pack reports that using the link order C<-lws2_32 -lmsvcrt-ruby-190> |
|
|
3578 | makes rev work even on mingw. |
|
|
3579 | |
|
|
3580 | =item Haskell |
|
|
3581 | |
|
|
3582 | A haskell binding to libev is available at |
|
|
3583 | L<http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hlibev>. |
|
|
3584 | |
2958 | =item D |
3585 | =item D |
2959 | |
3586 | |
2960 | Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to |
3587 | Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to |
2961 | be found at L<http://proj.llucax.com.ar/wiki/evd>. |
3588 | be found at L<http://proj.llucax.com.ar/wiki/evd>. |
2962 | |
3589 | |
2963 | =item Ocaml |
3590 | =item Ocaml |
2964 | |
3591 | |
2965 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3592 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
2966 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
3593 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
|
|
3594 | |
|
|
3595 | =item Lua |
|
|
3596 | |
|
|
3597 | Brian Maher has written a partial interface to libev for lua (at the |
|
|
3598 | time of this writing, only C<ev_io> and C<ev_timer>), to be found at |
|
|
3599 | L<http://github.com/brimworks/lua-ev>. |
2967 | |
3600 | |
2968 | =back |
3601 | =back |
2969 | |
3602 | |
2970 | |
3603 | |
2971 | =head1 MACRO MAGIC |
3604 | =head1 MACRO MAGIC |
… | |
… | |
2985 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
3618 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
2986 | C<EV_A_> is used when other arguments are following. Example: |
3619 | C<EV_A_> is used when other arguments are following. Example: |
2987 | |
3620 | |
2988 | ev_unref (EV_A); |
3621 | ev_unref (EV_A); |
2989 | ev_timer_add (EV_A_ watcher); |
3622 | ev_timer_add (EV_A_ watcher); |
2990 | ev_loop (EV_A_ 0); |
3623 | ev_run (EV_A_ 0); |
2991 | |
3624 | |
2992 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
3625 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
2993 | which is often provided by the following macro. |
3626 | which is often provided by the following macro. |
2994 | |
3627 | |
2995 | =item C<EV_P>, C<EV_P_> |
3628 | =item C<EV_P>, C<EV_P_> |
… | |
… | |
3035 | } |
3668 | } |
3036 | |
3669 | |
3037 | ev_check check; |
3670 | ev_check check; |
3038 | ev_check_init (&check, check_cb); |
3671 | ev_check_init (&check, check_cb); |
3039 | ev_check_start (EV_DEFAULT_ &check); |
3672 | ev_check_start (EV_DEFAULT_ &check); |
3040 | ev_loop (EV_DEFAULT_ 0); |
3673 | ev_run (EV_DEFAULT_ 0); |
3041 | |
3674 | |
3042 | =head1 EMBEDDING |
3675 | =head1 EMBEDDING |
3043 | |
3676 | |
3044 | Libev can (and often is) directly embedded into host |
3677 | Libev can (and often is) directly embedded into host |
3045 | applications. Examples of applications that embed it include the Deliantra |
3678 | applications. Examples of applications that embed it include the Deliantra |
… | |
… | |
3072 | |
3705 | |
3073 | #define EV_STANDALONE 1 |
3706 | #define EV_STANDALONE 1 |
3074 | #include "ev.h" |
3707 | #include "ev.h" |
3075 | |
3708 | |
3076 | Both header files and implementation files can be compiled with a C++ |
3709 | Both header files and implementation files can be compiled with a C++ |
3077 | compiler (at least, thats a stated goal, and breakage will be treated |
3710 | compiler (at least, that's a stated goal, and breakage will be treated |
3078 | as a bug). |
3711 | as a bug). |
3079 | |
3712 | |
3080 | You need the following files in your source tree, or in a directory |
3713 | You need the following files in your source tree, or in a directory |
3081 | in your include path (e.g. in libev/ when using -Ilibev): |
3714 | in your include path (e.g. in libev/ when using -Ilibev): |
3082 | |
3715 | |
… | |
… | |
3125 | libev.m4 |
3758 | libev.m4 |
3126 | |
3759 | |
3127 | =head2 PREPROCESSOR SYMBOLS/MACROS |
3760 | =head2 PREPROCESSOR SYMBOLS/MACROS |
3128 | |
3761 | |
3129 | Libev can be configured via a variety of preprocessor symbols you have to |
3762 | Libev can be configured via a variety of preprocessor symbols you have to |
3130 | define before including any of its files. The default in the absence of |
3763 | define before including (or compiling) any of its files. The default in |
3131 | autoconf is documented for every option. |
3764 | the absence of autoconf is documented for every option. |
|
|
3765 | |
|
|
3766 | Symbols marked with "(h)" do not change the ABI, and can have different |
|
|
3767 | values when compiling libev vs. including F<ev.h>, so it is permissible |
|
|
3768 | to redefine them before including F<ev.h> without breaking compatibility |
|
|
3769 | to a compiled library. All other symbols change the ABI, which means all |
|
|
3770 | users of libev and the libev code itself must be compiled with compatible |
|
|
3771 | settings. |
3132 | |
3772 | |
3133 | =over 4 |
3773 | =over 4 |
3134 | |
3774 | |
|
|
3775 | =item EV_COMPAT3 (h) |
|
|
3776 | |
|
|
3777 | Backwards compatibility is a major concern for libev. This is why this |
|
|
3778 | release of libev comes with wrappers for the functions and symbols that |
|
|
3779 | have been renamed between libev version 3 and 4. |
|
|
3780 | |
|
|
3781 | You can disable these wrappers (to test compatibility with future |
|
|
3782 | versions) by defining C<EV_COMPAT3> to C<0> when compiling your |
|
|
3783 | sources. This has the additional advantage that you can drop the C<struct> |
|
|
3784 | from C<struct ev_loop> declarations, as libev will provide an C<ev_loop> |
|
|
3785 | typedef in that case. |
|
|
3786 | |
|
|
3787 | In some future version, the default for C<EV_COMPAT3> will become C<0>, |
|
|
3788 | and in some even more future version the compatibility code will be |
|
|
3789 | removed completely. |
|
|
3790 | |
3135 | =item EV_STANDALONE |
3791 | =item EV_STANDALONE (h) |
3136 | |
3792 | |
3137 | Must always be C<1> if you do not use autoconf configuration, which |
3793 | Must always be C<1> if you do not use autoconf configuration, which |
3138 | keeps libev from including F<config.h>, and it also defines dummy |
3794 | keeps libev from including F<config.h>, and it also defines dummy |
3139 | implementations for some libevent functions (such as logging, which is not |
3795 | implementations for some libevent functions (such as logging, which is not |
3140 | supported). It will also not define any of the structs usually found in |
3796 | supported). It will also not define any of the structs usually found in |
3141 | F<event.h> that are not directly supported by the libev core alone. |
3797 | F<event.h> that are not directly supported by the libev core alone. |
3142 | |
3798 | |
|
|
3799 | In standalone mode, libev will still try to automatically deduce the |
|
|
3800 | configuration, but has to be more conservative. |
|
|
3801 | |
3143 | =item EV_USE_MONOTONIC |
3802 | =item EV_USE_MONOTONIC |
3144 | |
3803 | |
3145 | If defined to be C<1>, libev will try to detect the availability of the |
3804 | If defined to be C<1>, libev will try to detect the availability of the |
3146 | monotonic clock option at both compile time and runtime. Otherwise no use |
3805 | monotonic clock option at both compile time and runtime. Otherwise no |
3147 | of the monotonic clock option will be attempted. If you enable this, you |
3806 | use of the monotonic clock option will be attempted. If you enable this, |
3148 | usually have to link against librt or something similar. Enabling it when |
3807 | you usually have to link against librt or something similar. Enabling it |
3149 | the functionality isn't available is safe, though, although you have |
3808 | when the functionality isn't available is safe, though, although you have |
3150 | to make sure you link against any libraries where the C<clock_gettime> |
3809 | to make sure you link against any libraries where the C<clock_gettime> |
3151 | function is hiding in (often F<-lrt>). |
3810 | function is hiding in (often F<-lrt>). See also C<EV_USE_CLOCK_SYSCALL>. |
3152 | |
3811 | |
3153 | =item EV_USE_REALTIME |
3812 | =item EV_USE_REALTIME |
3154 | |
3813 | |
3155 | If defined to be C<1>, libev will try to detect the availability of the |
3814 | If defined to be C<1>, libev will try to detect the availability of the |
3156 | real-time clock option at compile time (and assume its availability at |
3815 | real-time clock option at compile time (and assume its availability |
3157 | runtime if successful). Otherwise no use of the real-time clock option will |
3816 | at runtime if successful). Otherwise no use of the real-time clock |
3158 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
3817 | option will be attempted. This effectively replaces C<gettimeofday> |
3159 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See the |
3818 | by C<clock_get (CLOCK_REALTIME, ...)> and will not normally affect |
3160 | note about libraries in the description of C<EV_USE_MONOTONIC>, though. |
3819 | correctness. See the note about libraries in the description of |
|
|
3820 | C<EV_USE_MONOTONIC>, though. Defaults to the opposite value of |
|
|
3821 | C<EV_USE_CLOCK_SYSCALL>. |
|
|
3822 | |
|
|
3823 | =item EV_USE_CLOCK_SYSCALL |
|
|
3824 | |
|
|
3825 | If defined to be C<1>, libev will try to use a direct syscall instead |
|
|
3826 | of calling the system-provided C<clock_gettime> function. This option |
|
|
3827 | exists because on GNU/Linux, C<clock_gettime> is in C<librt>, but C<librt> |
|
|
3828 | unconditionally pulls in C<libpthread>, slowing down single-threaded |
|
|
3829 | programs needlessly. Using a direct syscall is slightly slower (in |
|
|
3830 | theory), because no optimised vdso implementation can be used, but avoids |
|
|
3831 | the pthread dependency. Defaults to C<1> on GNU/Linux with glibc 2.x or |
|
|
3832 | higher, as it simplifies linking (no need for C<-lrt>). |
3161 | |
3833 | |
3162 | =item EV_USE_NANOSLEEP |
3834 | =item EV_USE_NANOSLEEP |
3163 | |
3835 | |
3164 | If defined to be C<1>, libev will assume that C<nanosleep ()> is available |
3836 | If defined to be C<1>, libev will assume that C<nanosleep ()> is available |
3165 | and will use it for delays. Otherwise it will use C<select ()>. |
3837 | and will use it for delays. Otherwise it will use C<select ()>. |
… | |
… | |
3181 | |
3853 | |
3182 | =item EV_SELECT_USE_FD_SET |
3854 | =item EV_SELECT_USE_FD_SET |
3183 | |
3855 | |
3184 | If defined to C<1>, then the select backend will use the system C<fd_set> |
3856 | If defined to C<1>, then the select backend will use the system C<fd_set> |
3185 | structure. This is useful if libev doesn't compile due to a missing |
3857 | structure. This is useful if libev doesn't compile due to a missing |
3186 | C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout on |
3858 | C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout |
3187 | exotic systems. This usually limits the range of file descriptors to some |
3859 | on exotic systems. This usually limits the range of file descriptors to |
3188 | low limit such as 1024 or might have other limitations (winsocket only |
3860 | some low limit such as 1024 or might have other limitations (winsocket |
3189 | allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might |
3861 | only allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, |
3190 | influence the size of the C<fd_set> used. |
3862 | configures the maximum size of the C<fd_set>. |
3191 | |
3863 | |
3192 | =item EV_SELECT_IS_WINSOCKET |
3864 | =item EV_SELECT_IS_WINSOCKET |
3193 | |
3865 | |
3194 | When defined to C<1>, the select backend will assume that |
3866 | When defined to C<1>, the select backend will assume that |
3195 | select/socket/connect etc. don't understand file descriptors but |
3867 | select/socket/connect etc. don't understand file descriptors but |
… | |
… | |
3197 | be used is the winsock select). This means that it will call |
3869 | be used is the winsock select). This means that it will call |
3198 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
3870 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
3199 | it is assumed that all these functions actually work on fds, even |
3871 | it is assumed that all these functions actually work on fds, even |
3200 | on win32. Should not be defined on non-win32 platforms. |
3872 | on win32. Should not be defined on non-win32 platforms. |
3201 | |
3873 | |
3202 | =item EV_FD_TO_WIN32_HANDLE |
3874 | =item EV_FD_TO_WIN32_HANDLE(fd) |
3203 | |
3875 | |
3204 | If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map |
3876 | If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map |
3205 | file descriptors to socket handles. When not defining this symbol (the |
3877 | file descriptors to socket handles. When not defining this symbol (the |
3206 | default), then libev will call C<_get_osfhandle>, which is usually |
3878 | default), then libev will call C<_get_osfhandle>, which is usually |
3207 | correct. In some cases, programs use their own file descriptor management, |
3879 | correct. In some cases, programs use their own file descriptor management, |
3208 | in which case they can provide this function to map fds to socket handles. |
3880 | in which case they can provide this function to map fds to socket handles. |
|
|
3881 | |
|
|
3882 | =item EV_WIN32_HANDLE_TO_FD(handle) |
|
|
3883 | |
|
|
3884 | If C<EV_SELECT_IS_WINSOCKET> then libev maps handles to file descriptors |
|
|
3885 | using the standard C<_open_osfhandle> function. For programs implementing |
|
|
3886 | their own fd to handle mapping, overwriting this function makes it easier |
|
|
3887 | to do so. This can be done by defining this macro to an appropriate value. |
|
|
3888 | |
|
|
3889 | =item EV_WIN32_CLOSE_FD(fd) |
|
|
3890 | |
|
|
3891 | If programs implement their own fd to handle mapping on win32, then this |
|
|
3892 | macro can be used to override the C<close> function, useful to unregister |
|
|
3893 | file descriptors again. Note that the replacement function has to close |
|
|
3894 | the underlying OS handle. |
3209 | |
3895 | |
3210 | =item EV_USE_POLL |
3896 | =item EV_USE_POLL |
3211 | |
3897 | |
3212 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
3898 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
3213 | backend. Otherwise it will be enabled on non-win32 platforms. It |
3899 | backend. Otherwise it will be enabled on non-win32 platforms. It |
… | |
… | |
3260 | as well as for signal and thread safety in C<ev_async> watchers. |
3946 | as well as for signal and thread safety in C<ev_async> watchers. |
3261 | |
3947 | |
3262 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
3948 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
3263 | (from F<signal.h>), which is usually good enough on most platforms. |
3949 | (from F<signal.h>), which is usually good enough on most platforms. |
3264 | |
3950 | |
3265 | =item EV_H |
3951 | =item EV_H (h) |
3266 | |
3952 | |
3267 | The name of the F<ev.h> header file used to include it. The default if |
3953 | The name of the F<ev.h> header file used to include it. The default if |
3268 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
3954 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
3269 | used to virtually rename the F<ev.h> header file in case of conflicts. |
3955 | used to virtually rename the F<ev.h> header file in case of conflicts. |
3270 | |
3956 | |
3271 | =item EV_CONFIG_H |
3957 | =item EV_CONFIG_H (h) |
3272 | |
3958 | |
3273 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
3959 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
3274 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
3960 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
3275 | C<EV_H>, above. |
3961 | C<EV_H>, above. |
3276 | |
3962 | |
3277 | =item EV_EVENT_H |
3963 | =item EV_EVENT_H (h) |
3278 | |
3964 | |
3279 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
3965 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
3280 | of how the F<event.h> header can be found, the default is C<"event.h">. |
3966 | of how the F<event.h> header can be found, the default is C<"event.h">. |
3281 | |
3967 | |
3282 | =item EV_PROTOTYPES |
3968 | =item EV_PROTOTYPES (h) |
3283 | |
3969 | |
3284 | If defined to be C<0>, then F<ev.h> will not define any function |
3970 | If defined to be C<0>, then F<ev.h> will not define any function |
3285 | prototypes, but still define all the structs and other symbols. This is |
3971 | prototypes, but still define all the structs and other symbols. This is |
3286 | occasionally useful if you want to provide your own wrapper functions |
3972 | occasionally useful if you want to provide your own wrapper functions |
3287 | around libev functions. |
3973 | around libev functions. |
… | |
… | |
3309 | fine. |
3995 | fine. |
3310 | |
3996 | |
3311 | If your embedding application does not need any priorities, defining these |
3997 | If your embedding application does not need any priorities, defining these |
3312 | both to C<0> will save some memory and CPU. |
3998 | both to C<0> will save some memory and CPU. |
3313 | |
3999 | |
3314 | =item EV_PERIODIC_ENABLE |
4000 | =item EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE, |
|
|
4001 | EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE, |
|
|
4002 | EV_ASYNC_ENABLE, EV_CHILD_ENABLE. |
3315 | |
4003 | |
3316 | If undefined or defined to be C<1>, then periodic timers are supported. If |
4004 | If undefined or defined to be C<1> (and the platform supports it), then |
3317 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
4005 | the respective watcher type is supported. If defined to be C<0>, then it |
3318 | code. |
4006 | is not. Disabling watcher types mainly saves code size. |
3319 | |
4007 | |
3320 | =item EV_IDLE_ENABLE |
4008 | =item EV_FEATURES |
3321 | |
|
|
3322 | If undefined or defined to be C<1>, then idle watchers are supported. If |
|
|
3323 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
3324 | code. |
|
|
3325 | |
|
|
3326 | =item EV_EMBED_ENABLE |
|
|
3327 | |
|
|
3328 | If undefined or defined to be C<1>, then embed watchers are supported. If |
|
|
3329 | defined to be C<0>, then they are not. Embed watchers rely on most other |
|
|
3330 | watcher types, which therefore must not be disabled. |
|
|
3331 | |
|
|
3332 | =item EV_STAT_ENABLE |
|
|
3333 | |
|
|
3334 | If undefined or defined to be C<1>, then stat watchers are supported. If |
|
|
3335 | defined to be C<0>, then they are not. |
|
|
3336 | |
|
|
3337 | =item EV_FORK_ENABLE |
|
|
3338 | |
|
|
3339 | If undefined or defined to be C<1>, then fork watchers are supported. If |
|
|
3340 | defined to be C<0>, then they are not. |
|
|
3341 | |
|
|
3342 | =item EV_ASYNC_ENABLE |
|
|
3343 | |
|
|
3344 | If undefined or defined to be C<1>, then async watchers are supported. If |
|
|
3345 | defined to be C<0>, then they are not. |
|
|
3346 | |
|
|
3347 | =item EV_MINIMAL |
|
|
3348 | |
4009 | |
3349 | If you need to shave off some kilobytes of code at the expense of some |
4010 | If you need to shave off some kilobytes of code at the expense of some |
3350 | speed, define this symbol to C<1>. Currently this is used to override some |
4011 | speed (but with the full API), you can define this symbol to request |
3351 | inlining decisions, saves roughly 30% code size on amd64. It also selects a |
4012 | certain subsets of functionality. The default is to enable all features |
3352 | much smaller 2-heap for timer management over the default 4-heap. |
4013 | that can be enabled on the platform. |
|
|
4014 | |
|
|
4015 | A typical way to use this symbol is to define it to C<0> (or to a bitset |
|
|
4016 | with some broad features you want) and then selectively re-enable |
|
|
4017 | additional parts you want, for example if you want everything minimal, |
|
|
4018 | but multiple event loop support, async and child watchers and the poll |
|
|
4019 | backend, use this: |
|
|
4020 | |
|
|
4021 | #define EV_FEATURES 0 |
|
|
4022 | #define EV_MULTIPLICITY 1 |
|
|
4023 | #define EV_USE_POLL 1 |
|
|
4024 | #define EV_CHILD_ENABLE 1 |
|
|
4025 | #define EV_ASYNC_ENABLE 1 |
|
|
4026 | |
|
|
4027 | The actual value is a bitset, it can be a combination of the following |
|
|
4028 | values: |
|
|
4029 | |
|
|
4030 | =over 4 |
|
|
4031 | |
|
|
4032 | =item C<1> - faster/larger code |
|
|
4033 | |
|
|
4034 | Use larger code to speed up some operations. |
|
|
4035 | |
|
|
4036 | Currently this is used to override some inlining decisions (enlarging the |
|
|
4037 | code size by roughly 30% on amd64). |
|
|
4038 | |
|
|
4039 | When optimising for size, use of compiler flags such as C<-Os> with |
|
|
4040 | gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of |
|
|
4041 | assertions. |
|
|
4042 | |
|
|
4043 | =item C<2> - faster/larger data structures |
|
|
4044 | |
|
|
4045 | Replaces the small 2-heap for timer management by a faster 4-heap, larger |
|
|
4046 | hash table sizes and so on. This will usually further increase code size |
|
|
4047 | and can additionally have an effect on the size of data structures at |
|
|
4048 | runtime. |
|
|
4049 | |
|
|
4050 | =item C<4> - full API configuration |
|
|
4051 | |
|
|
4052 | This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and |
|
|
4053 | enables multiplicity (C<EV_MULTIPLICITY>=1). |
|
|
4054 | |
|
|
4055 | =item C<8> - full API |
|
|
4056 | |
|
|
4057 | This enables a lot of the "lesser used" API functions. See C<ev.h> for |
|
|
4058 | details on which parts of the API are still available without this |
|
|
4059 | feature, and do not complain if this subset changes over time. |
|
|
4060 | |
|
|
4061 | =item C<16> - enable all optional watcher types |
|
|
4062 | |
|
|
4063 | Enables all optional watcher types. If you want to selectively enable |
|
|
4064 | only some watcher types other than I/O and timers (e.g. prepare, |
|
|
4065 | embed, async, child...) you can enable them manually by defining |
|
|
4066 | C<EV_watchertype_ENABLE> to C<1> instead. |
|
|
4067 | |
|
|
4068 | =item C<32> - enable all backends |
|
|
4069 | |
|
|
4070 | This enables all backends - without this feature, you need to enable at |
|
|
4071 | least one backend manually (C<EV_USE_SELECT> is a good choice). |
|
|
4072 | |
|
|
4073 | =item C<64> - enable OS-specific "helper" APIs |
|
|
4074 | |
|
|
4075 | Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by |
|
|
4076 | default. |
|
|
4077 | |
|
|
4078 | =back |
|
|
4079 | |
|
|
4080 | Compiling with C<gcc -Os -DEV_STANDALONE -DEV_USE_EPOLL=1 -DEV_FEATURES=0> |
|
|
4081 | reduces the compiled size of libev from 24.7Kb code/2.8Kb data to 6.5Kb |
|
|
4082 | code/0.3Kb data on my GNU/Linux amd64 system, while still giving you I/O |
|
|
4083 | watchers, timers and monotonic clock support. |
|
|
4084 | |
|
|
4085 | With an intelligent-enough linker (gcc+binutils are intelligent enough |
|
|
4086 | when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by |
|
|
4087 | your program might be left out as well - a binary starting a timer and an |
|
|
4088 | I/O watcher then might come out at only 5Kb. |
|
|
4089 | |
|
|
4090 | =item EV_AVOID_STDIO |
|
|
4091 | |
|
|
4092 | If this is set to C<1> at compiletime, then libev will avoid using stdio |
|
|
4093 | functions (printf, scanf, perror etc.). This will increase the code size |
|
|
4094 | somewhat, but if your program doesn't otherwise depend on stdio and your |
|
|
4095 | libc allows it, this avoids linking in the stdio library which is quite |
|
|
4096 | big. |
|
|
4097 | |
|
|
4098 | Note that error messages might become less precise when this option is |
|
|
4099 | enabled. |
|
|
4100 | |
|
|
4101 | =item EV_NSIG |
|
|
4102 | |
|
|
4103 | The highest supported signal number, +1 (or, the number of |
|
|
4104 | signals): Normally, libev tries to deduce the maximum number of signals |
|
|
4105 | automatically, but sometimes this fails, in which case it can be |
|
|
4106 | specified. Also, using a lower number than detected (C<32> should be |
|
|
4107 | good for about any system in existence) can save some memory, as libev |
|
|
4108 | statically allocates some 12-24 bytes per signal number. |
3353 | |
4109 | |
3354 | =item EV_PID_HASHSIZE |
4110 | =item EV_PID_HASHSIZE |
3355 | |
4111 | |
3356 | C<ev_child> watchers use a small hash table to distribute workload by |
4112 | C<ev_child> watchers use a small hash table to distribute workload by |
3357 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
4113 | pid. The default size is C<16> (or C<1> with C<EV_FEATURES> disabled), |
3358 | than enough. If you need to manage thousands of children you might want to |
4114 | usually more than enough. If you need to manage thousands of children you |
3359 | increase this value (I<must> be a power of two). |
4115 | might want to increase this value (I<must> be a power of two). |
3360 | |
4116 | |
3361 | =item EV_INOTIFY_HASHSIZE |
4117 | =item EV_INOTIFY_HASHSIZE |
3362 | |
4118 | |
3363 | C<ev_stat> watchers use a small hash table to distribute workload by |
4119 | C<ev_stat> watchers use a small hash table to distribute workload by |
3364 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
4120 | inotify watch id. The default size is C<16> (or C<1> with C<EV_FEATURES> |
3365 | usually more than enough. If you need to manage thousands of C<ev_stat> |
4121 | disabled), usually more than enough. If you need to manage thousands of |
3366 | watchers you might want to increase this value (I<must> be a power of |
4122 | C<ev_stat> watchers you might want to increase this value (I<must> be a |
3367 | two). |
4123 | power of two). |
3368 | |
4124 | |
3369 | =item EV_USE_4HEAP |
4125 | =item EV_USE_4HEAP |
3370 | |
4126 | |
3371 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
4127 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3372 | timer and periodics heaps, libev uses a 4-heap when this symbol is defined |
4128 | timer and periodics heaps, libev uses a 4-heap when this symbol is defined |
3373 | to C<1>. The 4-heap uses more complicated (longer) code but has noticeably |
4129 | to C<1>. The 4-heap uses more complicated (longer) code but has noticeably |
3374 | faster performance with many (thousands) of watchers. |
4130 | faster performance with many (thousands) of watchers. |
3375 | |
4131 | |
3376 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
4132 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3377 | (disabled). |
4133 | will be C<0>. |
3378 | |
4134 | |
3379 | =item EV_HEAP_CACHE_AT |
4135 | =item EV_HEAP_CACHE_AT |
3380 | |
4136 | |
3381 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
4137 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3382 | timer and periodics heaps, libev can cache the timestamp (I<at>) within |
4138 | timer and periodics heaps, libev can cache the timestamp (I<at>) within |
3383 | the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>), |
4139 | the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>), |
3384 | which uses 8-12 bytes more per watcher and a few hundred bytes more code, |
4140 | which uses 8-12 bytes more per watcher and a few hundred bytes more code, |
3385 | but avoids random read accesses on heap changes. This improves performance |
4141 | but avoids random read accesses on heap changes. This improves performance |
3386 | noticeably with many (hundreds) of watchers. |
4142 | noticeably with many (hundreds) of watchers. |
3387 | |
4143 | |
3388 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
4144 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3389 | (disabled). |
4145 | will be C<0>. |
3390 | |
4146 | |
3391 | =item EV_VERIFY |
4147 | =item EV_VERIFY |
3392 | |
4148 | |
3393 | Controls how much internal verification (see C<ev_loop_verify ()>) will |
4149 | Controls how much internal verification (see C<ev_verify ()>) will |
3394 | be done: If set to C<0>, no internal verification code will be compiled |
4150 | be done: If set to C<0>, no internal verification code will be compiled |
3395 | in. If set to C<1>, then verification code will be compiled in, but not |
4151 | in. If set to C<1>, then verification code will be compiled in, but not |
3396 | called. If set to C<2>, then the internal verification code will be |
4152 | called. If set to C<2>, then the internal verification code will be |
3397 | called once per loop, which can slow down libev. If set to C<3>, then the |
4153 | called once per loop, which can slow down libev. If set to C<3>, then the |
3398 | verification code will be called very frequently, which will slow down |
4154 | verification code will be called very frequently, which will slow down |
3399 | libev considerably. |
4155 | libev considerably. |
3400 | |
4156 | |
3401 | The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be |
4157 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3402 | C<0>. |
4158 | will be C<0>. |
3403 | |
4159 | |
3404 | =item EV_COMMON |
4160 | =item EV_COMMON |
3405 | |
4161 | |
3406 | By default, all watchers have a C<void *data> member. By redefining |
4162 | By default, all watchers have a C<void *data> member. By redefining |
3407 | this macro to a something else you can include more and other types of |
4163 | this macro to something else you can include more and other types of |
3408 | members. You have to define it each time you include one of the files, |
4164 | members. You have to define it each time you include one of the files, |
3409 | though, and it must be identical each time. |
4165 | though, and it must be identical each time. |
3410 | |
4166 | |
3411 | For example, the perl EV module uses something like this: |
4167 | For example, the perl EV module uses something like this: |
3412 | |
4168 | |
… | |
… | |
3465 | file. |
4221 | file. |
3466 | |
4222 | |
3467 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
4223 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
3468 | that everybody includes and which overrides some configure choices: |
4224 | that everybody includes and which overrides some configure choices: |
3469 | |
4225 | |
3470 | #define EV_MINIMAL 1 |
4226 | #define EV_FEATURES 8 |
3471 | #define EV_USE_POLL 0 |
4227 | #define EV_USE_SELECT 1 |
3472 | #define EV_MULTIPLICITY 0 |
|
|
3473 | #define EV_PERIODIC_ENABLE 0 |
4228 | #define EV_PREPARE_ENABLE 1 |
|
|
4229 | #define EV_IDLE_ENABLE 1 |
3474 | #define EV_STAT_ENABLE 0 |
4230 | #define EV_SIGNAL_ENABLE 1 |
3475 | #define EV_FORK_ENABLE 0 |
4231 | #define EV_CHILD_ENABLE 1 |
|
|
4232 | #define EV_USE_STDEXCEPT 0 |
3476 | #define EV_CONFIG_H <config.h> |
4233 | #define EV_CONFIG_H <config.h> |
3477 | #define EV_MINPRI 0 |
|
|
3478 | #define EV_MAXPRI 0 |
|
|
3479 | |
4234 | |
3480 | #include "ev++.h" |
4235 | #include "ev++.h" |
3481 | |
4236 | |
3482 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
4237 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
3483 | |
4238 | |
… | |
… | |
3543 | default loop and triggering an C<ev_async> watcher from the default loop |
4298 | default loop and triggering an C<ev_async> watcher from the default loop |
3544 | watcher callback into the event loop interested in the signal. |
4299 | watcher callback into the event loop interested in the signal. |
3545 | |
4300 | |
3546 | =back |
4301 | =back |
3547 | |
4302 | |
|
|
4303 | =head4 THREAD LOCKING EXAMPLE |
|
|
4304 | |
|
|
4305 | Here is a fictitious example of how to run an event loop in a different |
|
|
4306 | thread than where callbacks are being invoked and watchers are |
|
|
4307 | created/added/removed. |
|
|
4308 | |
|
|
4309 | For a real-world example, see the C<EV::Loop::Async> perl module, |
|
|
4310 | which uses exactly this technique (which is suited for many high-level |
|
|
4311 | languages). |
|
|
4312 | |
|
|
4313 | The example uses a pthread mutex to protect the loop data, a condition |
|
|
4314 | variable to wait for callback invocations, an async watcher to notify the |
|
|
4315 | event loop thread and an unspecified mechanism to wake up the main thread. |
|
|
4316 | |
|
|
4317 | First, you need to associate some data with the event loop: |
|
|
4318 | |
|
|
4319 | typedef struct { |
|
|
4320 | mutex_t lock; /* global loop lock */ |
|
|
4321 | ev_async async_w; |
|
|
4322 | thread_t tid; |
|
|
4323 | cond_t invoke_cv; |
|
|
4324 | } userdata; |
|
|
4325 | |
|
|
4326 | void prepare_loop (EV_P) |
|
|
4327 | { |
|
|
4328 | // for simplicity, we use a static userdata struct. |
|
|
4329 | static userdata u; |
|
|
4330 | |
|
|
4331 | ev_async_init (&u->async_w, async_cb); |
|
|
4332 | ev_async_start (EV_A_ &u->async_w); |
|
|
4333 | |
|
|
4334 | pthread_mutex_init (&u->lock, 0); |
|
|
4335 | pthread_cond_init (&u->invoke_cv, 0); |
|
|
4336 | |
|
|
4337 | // now associate this with the loop |
|
|
4338 | ev_set_userdata (EV_A_ u); |
|
|
4339 | ev_set_invoke_pending_cb (EV_A_ l_invoke); |
|
|
4340 | ev_set_loop_release_cb (EV_A_ l_release, l_acquire); |
|
|
4341 | |
|
|
4342 | // then create the thread running ev_loop |
|
|
4343 | pthread_create (&u->tid, 0, l_run, EV_A); |
|
|
4344 | } |
|
|
4345 | |
|
|
4346 | The callback for the C<ev_async> watcher does nothing: the watcher is used |
|
|
4347 | solely to wake up the event loop so it takes notice of any new watchers |
|
|
4348 | that might have been added: |
|
|
4349 | |
|
|
4350 | static void |
|
|
4351 | async_cb (EV_P_ ev_async *w, int revents) |
|
|
4352 | { |
|
|
4353 | // just used for the side effects |
|
|
4354 | } |
|
|
4355 | |
|
|
4356 | The C<l_release> and C<l_acquire> callbacks simply unlock/lock the mutex |
|
|
4357 | protecting the loop data, respectively. |
|
|
4358 | |
|
|
4359 | static void |
|
|
4360 | l_release (EV_P) |
|
|
4361 | { |
|
|
4362 | userdata *u = ev_userdata (EV_A); |
|
|
4363 | pthread_mutex_unlock (&u->lock); |
|
|
4364 | } |
|
|
4365 | |
|
|
4366 | static void |
|
|
4367 | l_acquire (EV_P) |
|
|
4368 | { |
|
|
4369 | userdata *u = ev_userdata (EV_A); |
|
|
4370 | pthread_mutex_lock (&u->lock); |
|
|
4371 | } |
|
|
4372 | |
|
|
4373 | The event loop thread first acquires the mutex, and then jumps straight |
|
|
4374 | into C<ev_run>: |
|
|
4375 | |
|
|
4376 | void * |
|
|
4377 | l_run (void *thr_arg) |
|
|
4378 | { |
|
|
4379 | struct ev_loop *loop = (struct ev_loop *)thr_arg; |
|
|
4380 | |
|
|
4381 | l_acquire (EV_A); |
|
|
4382 | pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
|
|
4383 | ev_run (EV_A_ 0); |
|
|
4384 | l_release (EV_A); |
|
|
4385 | |
|
|
4386 | return 0; |
|
|
4387 | } |
|
|
4388 | |
|
|
4389 | Instead of invoking all pending watchers, the C<l_invoke> callback will |
|
|
4390 | signal the main thread via some unspecified mechanism (signals? pipe |
|
|
4391 | writes? C<Async::Interrupt>?) and then waits until all pending watchers |
|
|
4392 | have been called (in a while loop because a) spurious wakeups are possible |
|
|
4393 | and b) skipping inter-thread-communication when there are no pending |
|
|
4394 | watchers is very beneficial): |
|
|
4395 | |
|
|
4396 | static void |
|
|
4397 | l_invoke (EV_P) |
|
|
4398 | { |
|
|
4399 | userdata *u = ev_userdata (EV_A); |
|
|
4400 | |
|
|
4401 | while (ev_pending_count (EV_A)) |
|
|
4402 | { |
|
|
4403 | wake_up_other_thread_in_some_magic_or_not_so_magic_way (); |
|
|
4404 | pthread_cond_wait (&u->invoke_cv, &u->lock); |
|
|
4405 | } |
|
|
4406 | } |
|
|
4407 | |
|
|
4408 | Now, whenever the main thread gets told to invoke pending watchers, it |
|
|
4409 | will grab the lock, call C<ev_invoke_pending> and then signal the loop |
|
|
4410 | thread to continue: |
|
|
4411 | |
|
|
4412 | static void |
|
|
4413 | real_invoke_pending (EV_P) |
|
|
4414 | { |
|
|
4415 | userdata *u = ev_userdata (EV_A); |
|
|
4416 | |
|
|
4417 | pthread_mutex_lock (&u->lock); |
|
|
4418 | ev_invoke_pending (EV_A); |
|
|
4419 | pthread_cond_signal (&u->invoke_cv); |
|
|
4420 | pthread_mutex_unlock (&u->lock); |
|
|
4421 | } |
|
|
4422 | |
|
|
4423 | Whenever you want to start/stop a watcher or do other modifications to an |
|
|
4424 | event loop, you will now have to lock: |
|
|
4425 | |
|
|
4426 | ev_timer timeout_watcher; |
|
|
4427 | userdata *u = ev_userdata (EV_A); |
|
|
4428 | |
|
|
4429 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
|
|
4430 | |
|
|
4431 | pthread_mutex_lock (&u->lock); |
|
|
4432 | ev_timer_start (EV_A_ &timeout_watcher); |
|
|
4433 | ev_async_send (EV_A_ &u->async_w); |
|
|
4434 | pthread_mutex_unlock (&u->lock); |
|
|
4435 | |
|
|
4436 | Note that sending the C<ev_async> watcher is required because otherwise |
|
|
4437 | an event loop currently blocking in the kernel will have no knowledge |
|
|
4438 | about the newly added timer. By waking up the loop it will pick up any new |
|
|
4439 | watchers in the next event loop iteration. |
|
|
4440 | |
3548 | =head3 COROUTINES |
4441 | =head3 COROUTINES |
3549 | |
4442 | |
3550 | Libev is very accommodating to coroutines ("cooperative threads"): |
4443 | Libev is very accommodating to coroutines ("cooperative threads"): |
3551 | libev fully supports nesting calls to its functions from different |
4444 | libev fully supports nesting calls to its functions from different |
3552 | coroutines (e.g. you can call C<ev_loop> on the same loop from two |
4445 | coroutines (e.g. you can call C<ev_run> on the same loop from two |
3553 | different coroutines, and switch freely between both coroutines running the |
4446 | different coroutines, and switch freely between both coroutines running |
3554 | loop, as long as you don't confuse yourself). The only exception is that |
4447 | the loop, as long as you don't confuse yourself). The only exception is |
3555 | you must not do this from C<ev_periodic> reschedule callbacks. |
4448 | that you must not do this from C<ev_periodic> reschedule callbacks. |
3556 | |
4449 | |
3557 | Care has been taken to ensure that libev does not keep local state inside |
4450 | Care has been taken to ensure that libev does not keep local state inside |
3558 | C<ev_loop>, and other calls do not usually allow for coroutine switches as |
4451 | C<ev_run>, and other calls do not usually allow for coroutine switches as |
3559 | they do not clal any callbacks. |
4452 | they do not call any callbacks. |
3560 | |
4453 | |
3561 | =head2 COMPILER WARNINGS |
4454 | =head2 COMPILER WARNINGS |
3562 | |
4455 | |
3563 | Depending on your compiler and compiler settings, you might get no or a |
4456 | Depending on your compiler and compiler settings, you might get no or a |
3564 | lot of warnings when compiling libev code. Some people are apparently |
4457 | lot of warnings when compiling libev code. Some people are apparently |
… | |
… | |
3574 | maintainable. |
4467 | maintainable. |
3575 | |
4468 | |
3576 | And of course, some compiler warnings are just plain stupid, or simply |
4469 | And of course, some compiler warnings are just plain stupid, or simply |
3577 | wrong (because they don't actually warn about the condition their message |
4470 | wrong (because they don't actually warn about the condition their message |
3578 | seems to warn about). For example, certain older gcc versions had some |
4471 | seems to warn about). For example, certain older gcc versions had some |
3579 | warnings that resulted an extreme number of false positives. These have |
4472 | warnings that resulted in an extreme number of false positives. These have |
3580 | been fixed, but some people still insist on making code warn-free with |
4473 | been fixed, but some people still insist on making code warn-free with |
3581 | such buggy versions. |
4474 | such buggy versions. |
3582 | |
4475 | |
3583 | While libev is written to generate as few warnings as possible, |
4476 | While libev is written to generate as few warnings as possible, |
3584 | "warn-free" code is not a goal, and it is recommended not to build libev |
4477 | "warn-free" code is not a goal, and it is recommended not to build libev |
… | |
… | |
3598 | ==2274== definitely lost: 0 bytes in 0 blocks. |
4491 | ==2274== definitely lost: 0 bytes in 0 blocks. |
3599 | ==2274== possibly lost: 0 bytes in 0 blocks. |
4492 | ==2274== possibly lost: 0 bytes in 0 blocks. |
3600 | ==2274== still reachable: 256 bytes in 1 blocks. |
4493 | ==2274== still reachable: 256 bytes in 1 blocks. |
3601 | |
4494 | |
3602 | Then there is no memory leak, just as memory accounted to global variables |
4495 | Then there is no memory leak, just as memory accounted to global variables |
3603 | is not a memleak - the memory is still being refernced, and didn't leak. |
4496 | is not a memleak - the memory is still being referenced, and didn't leak. |
3604 | |
4497 | |
3605 | Similarly, under some circumstances, valgrind might report kernel bugs |
4498 | Similarly, under some circumstances, valgrind might report kernel bugs |
3606 | as if it were a bug in libev (e.g. in realloc or in the poll backend, |
4499 | as if it were a bug in libev (e.g. in realloc or in the poll backend, |
3607 | although an acceptable workaround has been found here), or it might be |
4500 | although an acceptable workaround has been found here), or it might be |
3608 | confused. |
4501 | confused. |
… | |
… | |
3620 | I suggest using suppression lists. |
4513 | I suggest using suppression lists. |
3621 | |
4514 | |
3622 | |
4515 | |
3623 | =head1 PORTABILITY NOTES |
4516 | =head1 PORTABILITY NOTES |
3624 | |
4517 | |
|
|
4518 | =head2 GNU/LINUX 32 BIT LIMITATIONS |
|
|
4519 | |
|
|
4520 | GNU/Linux is the only common platform that supports 64 bit file/large file |
|
|
4521 | interfaces but I<disables> them by default. |
|
|
4522 | |
|
|
4523 | That means that libev compiled in the default environment doesn't support |
|
|
4524 | files larger than 2GiB or so, which mainly affects C<ev_stat> watchers. |
|
|
4525 | |
|
|
4526 | Unfortunately, many programs try to work around this GNU/Linux issue |
|
|
4527 | by enabling the large file API, which makes them incompatible with the |
|
|
4528 | standard libev compiled for their system. |
|
|
4529 | |
|
|
4530 | Likewise, libev cannot enable the large file API itself as this would |
|
|
4531 | suddenly make it incompatible to the default compile time environment, |
|
|
4532 | i.e. all programs not using special compile switches. |
|
|
4533 | |
|
|
4534 | =head2 OS/X AND DARWIN BUGS |
|
|
4535 | |
|
|
4536 | The whole thing is a bug if you ask me - basically any system interface |
|
|
4537 | you touch is broken, whether it is locales, poll, kqueue or even the |
|
|
4538 | OpenGL drivers. |
|
|
4539 | |
|
|
4540 | =head3 C<kqueue> is buggy |
|
|
4541 | |
|
|
4542 | The kqueue syscall is broken in all known versions - most versions support |
|
|
4543 | only sockets, many support pipes. |
|
|
4544 | |
|
|
4545 | Libev tries to work around this by not using C<kqueue> by default on this |
|
|
4546 | rotten platform, but of course you can still ask for it when creating a |
|
|
4547 | loop - embedding a socket-only kqueue loop into a select-based one is |
|
|
4548 | probably going to work well. |
|
|
4549 | |
|
|
4550 | =head3 C<poll> is buggy |
|
|
4551 | |
|
|
4552 | Instead of fixing C<kqueue>, Apple replaced their (working) C<poll> |
|
|
4553 | implementation by something calling C<kqueue> internally around the 10.5.6 |
|
|
4554 | release, so now C<kqueue> I<and> C<poll> are broken. |
|
|
4555 | |
|
|
4556 | Libev tries to work around this by not using C<poll> by default on |
|
|
4557 | this rotten platform, but of course you can still ask for it when creating |
|
|
4558 | a loop. |
|
|
4559 | |
|
|
4560 | =head3 C<select> is buggy |
|
|
4561 | |
|
|
4562 | All that's left is C<select>, and of course Apple found a way to fuck this |
|
|
4563 | one up as well: On OS/X, C<select> actively limits the number of file |
|
|
4564 | descriptors you can pass in to 1024 - your program suddenly crashes when |
|
|
4565 | you use more. |
|
|
4566 | |
|
|
4567 | There is an undocumented "workaround" for this - defining |
|
|
4568 | C<_DARWIN_UNLIMITED_SELECT>, which libev tries to use, so select I<should> |
|
|
4569 | work on OS/X. |
|
|
4570 | |
|
|
4571 | =head2 SOLARIS PROBLEMS AND WORKAROUNDS |
|
|
4572 | |
|
|
4573 | =head3 C<errno> reentrancy |
|
|
4574 | |
|
|
4575 | The default compile environment on Solaris is unfortunately so |
|
|
4576 | thread-unsafe that you can't even use components/libraries compiled |
|
|
4577 | without C<-D_REENTRANT> in a threaded program, which, of course, isn't |
|
|
4578 | defined by default. A valid, if stupid, implementation choice. |
|
|
4579 | |
|
|
4580 | If you want to use libev in threaded environments you have to make sure |
|
|
4581 | it's compiled with C<_REENTRANT> defined. |
|
|
4582 | |
|
|
4583 | =head3 Event port backend |
|
|
4584 | |
|
|
4585 | The scalable event interface for Solaris is called "event |
|
|
4586 | ports". Unfortunately, this mechanism is very buggy in all major |
|
|
4587 | releases. If you run into high CPU usage, your program freezes or you get |
|
|
4588 | a large number of spurious wakeups, make sure you have all the relevant |
|
|
4589 | and latest kernel patches applied. No, I don't know which ones, but there |
|
|
4590 | are multiple ones to apply, and afterwards, event ports actually work |
|
|
4591 | great. |
|
|
4592 | |
|
|
4593 | If you can't get it to work, you can try running the program by setting |
|
|
4594 | the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and |
|
|
4595 | C<select> backends. |
|
|
4596 | |
|
|
4597 | =head2 AIX POLL BUG |
|
|
4598 | |
|
|
4599 | AIX unfortunately has a broken C<poll.h> header. Libev works around |
|
|
4600 | this by trying to avoid the poll backend altogether (i.e. it's not even |
|
|
4601 | compiled in), which normally isn't a big problem as C<select> works fine |
|
|
4602 | with large bitsets on AIX, and AIX is dead anyway. |
|
|
4603 | |
3625 | =head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS |
4604 | =head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS |
|
|
4605 | |
|
|
4606 | =head3 General issues |
3626 | |
4607 | |
3627 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
4608 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
3628 | requires, and its I/O model is fundamentally incompatible with the POSIX |
4609 | requires, and its I/O model is fundamentally incompatible with the POSIX |
3629 | model. Libev still offers limited functionality on this platform in |
4610 | model. Libev still offers limited functionality on this platform in |
3630 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
4611 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
3631 | descriptors. This only applies when using Win32 natively, not when using |
4612 | descriptors. This only applies when using Win32 natively, not when using |
3632 | e.g. cygwin. |
4613 | e.g. cygwin. Actually, it only applies to the microsofts own compilers, |
|
|
4614 | as every compielr comes with a slightly differently broken/incompatible |
|
|
4615 | environment. |
3633 | |
4616 | |
3634 | Lifting these limitations would basically require the full |
4617 | Lifting these limitations would basically require the full |
3635 | re-implementation of the I/O system. If you are into these kinds of |
4618 | re-implementation of the I/O system. If you are into this kind of thing, |
3636 | things, then note that glib does exactly that for you in a very portable |
4619 | then note that glib does exactly that for you in a very portable way (note |
3637 | way (note also that glib is the slowest event library known to man). |
4620 | also that glib is the slowest event library known to man). |
3638 | |
4621 | |
3639 | There is no supported compilation method available on windows except |
4622 | There is no supported compilation method available on windows except |
3640 | embedding it into other applications. |
4623 | embedding it into other applications. |
|
|
4624 | |
|
|
4625 | Sensible signal handling is officially unsupported by Microsoft - libev |
|
|
4626 | tries its best, but under most conditions, signals will simply not work. |
3641 | |
4627 | |
3642 | Not a libev limitation but worth mentioning: windows apparently doesn't |
4628 | Not a libev limitation but worth mentioning: windows apparently doesn't |
3643 | accept large writes: instead of resulting in a partial write, windows will |
4629 | accept large writes: instead of resulting in a partial write, windows will |
3644 | either accept everything or return C<ENOBUFS> if the buffer is too large, |
4630 | either accept everything or return C<ENOBUFS> if the buffer is too large, |
3645 | so make sure you only write small amounts into your sockets (less than a |
4631 | so make sure you only write small amounts into your sockets (less than a |
… | |
… | |
3650 | the abysmal performance of winsockets, using a large number of sockets |
4636 | the abysmal performance of winsockets, using a large number of sockets |
3651 | is not recommended (and not reasonable). If your program needs to use |
4637 | is not recommended (and not reasonable). If your program needs to use |
3652 | more than a hundred or so sockets, then likely it needs to use a totally |
4638 | more than a hundred or so sockets, then likely it needs to use a totally |
3653 | different implementation for windows, as libev offers the POSIX readiness |
4639 | different implementation for windows, as libev offers the POSIX readiness |
3654 | notification model, which cannot be implemented efficiently on windows |
4640 | notification model, which cannot be implemented efficiently on windows |
3655 | (Microsoft monopoly games). |
4641 | (due to Microsoft monopoly games). |
3656 | |
4642 | |
3657 | A typical way to use libev under windows is to embed it (see the embedding |
4643 | A typical way to use libev under windows is to embed it (see the embedding |
3658 | section for details) and use the following F<evwrap.h> header file instead |
4644 | section for details) and use the following F<evwrap.h> header file instead |
3659 | of F<ev.h>: |
4645 | of F<ev.h>: |
3660 | |
4646 | |
… | |
… | |
3667 | you do I<not> compile the F<ev.c> or any other embedded source files!): |
4653 | you do I<not> compile the F<ev.c> or any other embedded source files!): |
3668 | |
4654 | |
3669 | #include "evwrap.h" |
4655 | #include "evwrap.h" |
3670 | #include "ev.c" |
4656 | #include "ev.c" |
3671 | |
4657 | |
3672 | =over 4 |
|
|
3673 | |
|
|
3674 | =item The winsocket select function |
4658 | =head3 The winsocket C<select> function |
3675 | |
4659 | |
3676 | The winsocket C<select> function doesn't follow POSIX in that it |
4660 | The winsocket C<select> function doesn't follow POSIX in that it |
3677 | requires socket I<handles> and not socket I<file descriptors> (it is |
4661 | requires socket I<handles> and not socket I<file descriptors> (it is |
3678 | also extremely buggy). This makes select very inefficient, and also |
4662 | also extremely buggy). This makes select very inefficient, and also |
3679 | requires a mapping from file descriptors to socket handles (the Microsoft |
4663 | requires a mapping from file descriptors to socket handles (the Microsoft |
… | |
… | |
3688 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
4672 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
3689 | |
4673 | |
3690 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
4674 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
3691 | complexity in the O(n²) range when using win32. |
4675 | complexity in the O(n²) range when using win32. |
3692 | |
4676 | |
3693 | =item Limited number of file descriptors |
4677 | =head3 Limited number of file descriptors |
3694 | |
4678 | |
3695 | Windows has numerous arbitrary (and low) limits on things. |
4679 | Windows has numerous arbitrary (and low) limits on things. |
3696 | |
4680 | |
3697 | Early versions of winsocket's select only supported waiting for a maximum |
4681 | Early versions of winsocket's select only supported waiting for a maximum |
3698 | of C<64> handles (probably owning to the fact that all windows kernels |
4682 | of C<64> handles (probably owning to the fact that all windows kernels |
3699 | can only wait for C<64> things at the same time internally; Microsoft |
4683 | can only wait for C<64> things at the same time internally; Microsoft |
3700 | recommends spawning a chain of threads and wait for 63 handles and the |
4684 | recommends spawning a chain of threads and wait for 63 handles and the |
3701 | previous thread in each. Great). |
4685 | previous thread in each. Sounds great!). |
3702 | |
4686 | |
3703 | Newer versions support more handles, but you need to define C<FD_SETSIZE> |
4687 | Newer versions support more handles, but you need to define C<FD_SETSIZE> |
3704 | to some high number (e.g. C<2048>) before compiling the winsocket select |
4688 | to some high number (e.g. C<2048>) before compiling the winsocket select |
3705 | call (which might be in libev or elsewhere, for example, perl does its own |
4689 | call (which might be in libev or elsewhere, for example, perl and many |
3706 | select emulation on windows). |
4690 | other interpreters do their own select emulation on windows). |
3707 | |
4691 | |
3708 | Another limit is the number of file descriptors in the Microsoft runtime |
4692 | Another limit is the number of file descriptors in the Microsoft runtime |
3709 | libraries, which by default is C<64> (there must be a hidden I<64> fetish |
4693 | libraries, which by default is C<64> (there must be a hidden I<64> |
3710 | or something like this inside Microsoft). You can increase this by calling |
4694 | fetish or something like this inside Microsoft). You can increase this |
3711 | C<_setmaxstdio>, which can increase this limit to C<2048> (another |
4695 | by calling C<_setmaxstdio>, which can increase this limit to C<2048> |
3712 | arbitrary limit), but is broken in many versions of the Microsoft runtime |
4696 | (another arbitrary limit), but is broken in many versions of the Microsoft |
3713 | libraries. |
|
|
3714 | |
|
|
3715 | This might get you to about C<512> or C<2048> sockets (depending on |
4697 | runtime libraries. This might get you to about C<512> or C<2048> sockets |
3716 | windows version and/or the phase of the moon). To get more, you need to |
4698 | (depending on windows version and/or the phase of the moon). To get more, |
3717 | wrap all I/O functions and provide your own fd management, but the cost of |
4699 | you need to wrap all I/O functions and provide your own fd management, but |
3718 | calling select (O(n²)) will likely make this unworkable. |
4700 | the cost of calling select (O(n²)) will likely make this unworkable. |
3719 | |
|
|
3720 | =back |
|
|
3721 | |
4701 | |
3722 | =head2 PORTABILITY REQUIREMENTS |
4702 | =head2 PORTABILITY REQUIREMENTS |
3723 | |
4703 | |
3724 | In addition to a working ISO-C implementation and of course the |
4704 | In addition to a working ISO-C implementation and of course the |
3725 | backend-specific APIs, libev relies on a few additional extensions: |
4705 | backend-specific APIs, libev relies on a few additional extensions: |
… | |
… | |
3764 | watchers. |
4744 | watchers. |
3765 | |
4745 | |
3766 | =item C<double> must hold a time value in seconds with enough accuracy |
4746 | =item C<double> must hold a time value in seconds with enough accuracy |
3767 | |
4747 | |
3768 | The type C<double> is used to represent timestamps. It is required to |
4748 | The type C<double> is used to represent timestamps. It is required to |
3769 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
4749 | have at least 51 bits of mantissa (and 9 bits of exponent), which is |
3770 | enough for at least into the year 4000. This requirement is fulfilled by |
4750 | good enough for at least into the year 4000 with millisecond accuracy |
|
|
4751 | (the design goal for libev). This requirement is overfulfilled by |
3771 | implementations implementing IEEE 754 (basically all existing ones). |
4752 | implementations using IEEE 754, which is basically all existing ones. With |
|
|
4753 | IEEE 754 doubles, you get microsecond accuracy until at least 2200. |
3772 | |
4754 | |
3773 | =back |
4755 | =back |
3774 | |
4756 | |
3775 | If you know of other additional requirements drop me a note. |
4757 | If you know of other additional requirements drop me a note. |
3776 | |
4758 | |
… | |
… | |
3844 | involves iterating over all running async watchers or all signal numbers. |
4826 | involves iterating over all running async watchers or all signal numbers. |
3845 | |
4827 | |
3846 | =back |
4828 | =back |
3847 | |
4829 | |
3848 | |
4830 | |
|
|
4831 | =head1 PORTING FROM LIBEV 3.X TO 4.X |
|
|
4832 | |
|
|
4833 | The major version 4 introduced some minor incompatible changes to the API. |
|
|
4834 | |
|
|
4835 | At the moment, the C<ev.h> header file tries to implement superficial |
|
|
4836 | compatibility, so most programs should still compile. Those might be |
|
|
4837 | removed in later versions of libev, so better update early than late. |
|
|
4838 | |
|
|
4839 | =over 4 |
|
|
4840 | |
|
|
4841 | =item C<ev_default_destroy> and C<ev_default_fork> have been removed |
|
|
4842 | |
|
|
4843 | These calls can be replaced easily by their C<ev_loop_xxx> counterparts: |
|
|
4844 | |
|
|
4845 | ev_loop_destroy (EV_DEFAULT); |
|
|
4846 | ev_loop_fork (EV_DEFAULT); |
|
|
4847 | |
|
|
4848 | =item function/symbol renames |
|
|
4849 | |
|
|
4850 | A number of functions and symbols have been renamed: |
|
|
4851 | |
|
|
4852 | ev_loop => ev_run |
|
|
4853 | EVLOOP_NONBLOCK => EVRUN_NOWAIT |
|
|
4854 | EVLOOP_ONESHOT => EVRUN_ONCE |
|
|
4855 | |
|
|
4856 | ev_unloop => ev_break |
|
|
4857 | EVUNLOOP_CANCEL => EVBREAK_CANCEL |
|
|
4858 | EVUNLOOP_ONE => EVBREAK_ONE |
|
|
4859 | EVUNLOOP_ALL => EVBREAK_ALL |
|
|
4860 | |
|
|
4861 | EV_TIMEOUT => EV_TIMER |
|
|
4862 | |
|
|
4863 | ev_loop_count => ev_iteration |
|
|
4864 | ev_loop_depth => ev_depth |
|
|
4865 | ev_loop_verify => ev_verify |
|
|
4866 | |
|
|
4867 | Most functions working on C<struct ev_loop> objects don't have an |
|
|
4868 | C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and |
|
|
4869 | associated constants have been renamed to not collide with the C<struct |
|
|
4870 | ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme |
|
|
4871 | as all other watcher types. Note that C<ev_loop_fork> is still called |
|
|
4872 | C<ev_loop_fork> because it would otherwise clash with the C<ev_fork> |
|
|
4873 | typedef. |
|
|
4874 | |
|
|
4875 | =item C<EV_COMPAT3> backwards compatibility mechanism |
|
|
4876 | |
|
|
4877 | The backward compatibility mechanism can be controlled by |
|
|
4878 | C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING> |
|
|
4879 | section. |
|
|
4880 | |
|
|
4881 | =item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES> |
|
|
4882 | |
|
|
4883 | The preprocessor symbol C<EV_MINIMAL> has been replaced by a different |
|
|
4884 | mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile |
|
|
4885 | and work, but the library code will of course be larger. |
|
|
4886 | |
|
|
4887 | =back |
|
|
4888 | |
|
|
4889 | |
|
|
4890 | =head1 GLOSSARY |
|
|
4891 | |
|
|
4892 | =over 4 |
|
|
4893 | |
|
|
4894 | =item active |
|
|
4895 | |
|
|
4896 | A watcher is active as long as it has been started and not yet stopped. |
|
|
4897 | See L<WATCHER STATES> for details. |
|
|
4898 | |
|
|
4899 | =item application |
|
|
4900 | |
|
|
4901 | In this document, an application is whatever is using libev. |
|
|
4902 | |
|
|
4903 | =item backend |
|
|
4904 | |
|
|
4905 | The part of the code dealing with the operating system interfaces. |
|
|
4906 | |
|
|
4907 | =item callback |
|
|
4908 | |
|
|
4909 | The address of a function that is called when some event has been |
|
|
4910 | detected. Callbacks are being passed the event loop, the watcher that |
|
|
4911 | received the event, and the actual event bitset. |
|
|
4912 | |
|
|
4913 | =item callback/watcher invocation |
|
|
4914 | |
|
|
4915 | The act of calling the callback associated with a watcher. |
|
|
4916 | |
|
|
4917 | =item event |
|
|
4918 | |
|
|
4919 | A change of state of some external event, such as data now being available |
|
|
4920 | for reading on a file descriptor, time having passed or simply not having |
|
|
4921 | any other events happening anymore. |
|
|
4922 | |
|
|
4923 | In libev, events are represented as single bits (such as C<EV_READ> or |
|
|
4924 | C<EV_TIMER>). |
|
|
4925 | |
|
|
4926 | =item event library |
|
|
4927 | |
|
|
4928 | A software package implementing an event model and loop. |
|
|
4929 | |
|
|
4930 | =item event loop |
|
|
4931 | |
|
|
4932 | An entity that handles and processes external events and converts them |
|
|
4933 | into callback invocations. |
|
|
4934 | |
|
|
4935 | =item event model |
|
|
4936 | |
|
|
4937 | The model used to describe how an event loop handles and processes |
|
|
4938 | watchers and events. |
|
|
4939 | |
|
|
4940 | =item pending |
|
|
4941 | |
|
|
4942 | A watcher is pending as soon as the corresponding event has been |
|
|
4943 | detected. See L<WATCHER STATES> for details. |
|
|
4944 | |
|
|
4945 | =item real time |
|
|
4946 | |
|
|
4947 | The physical time that is observed. It is apparently strictly monotonic :) |
|
|
4948 | |
|
|
4949 | =item wall-clock time |
|
|
4950 | |
|
|
4951 | The time and date as shown on clocks. Unlike real time, it can actually |
|
|
4952 | be wrong and jump forwards and backwards, e.g. when the you adjust your |
|
|
4953 | clock. |
|
|
4954 | |
|
|
4955 | =item watcher |
|
|
4956 | |
|
|
4957 | A data structure that describes interest in certain events. Watchers need |
|
|
4958 | to be started (attached to an event loop) before they can receive events. |
|
|
4959 | |
|
|
4960 | =back |
|
|
4961 | |
3849 | =head1 AUTHOR |
4962 | =head1 AUTHOR |
3850 | |
4963 | |
3851 | Marc Lehmann <libev@schmorp.de>. |
4964 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. |
3852 | |
4965 | |