… | |
… | |
4 | |
4 | |
5 | =head1 SYNOPSIS |
5 | =head1 SYNOPSIS |
6 | |
6 | |
7 | #include <ev.h> |
7 | #include <ev.h> |
8 | |
8 | |
9 | =head1 EXAMPLE PROGRAM |
9 | =head2 EXAMPLE PROGRAM |
10 | |
10 | |
11 | #include <ev.h> |
11 | #include <ev.h> |
12 | |
12 | |
13 | ev_io stdin_watcher; |
13 | ev_io stdin_watcher; |
14 | ev_timer timeout_watcher; |
14 | ev_timer timeout_watcher; |
… | |
… | |
48 | return 0; |
48 | return 0; |
49 | } |
49 | } |
50 | |
50 | |
51 | =head1 DESCRIPTION |
51 | =head1 DESCRIPTION |
52 | |
52 | |
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53 | The newest version of this document is also available as a html-formatted |
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54 | web page you might find easier to navigate when reading it for the first |
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55 | time: L<http://cvs.schmorp.de/libev/ev.html>. |
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56 | |
53 | Libev is an event loop: you register interest in certain events (such as a |
57 | Libev is an event loop: you register interest in certain events (such as a |
54 | file descriptor being readable or a timeout occuring), and it will manage |
58 | file descriptor being readable or a timeout occurring), and it will manage |
55 | these event sources and provide your program with events. |
59 | these event sources and provide your program with events. |
56 | |
60 | |
57 | To do this, it must take more or less complete control over your process |
61 | To do this, it must take more or less complete control over your process |
58 | (or thread) by executing the I<event loop> handler, and will then |
62 | (or thread) by executing the I<event loop> handler, and will then |
59 | communicate events via a callback mechanism. |
63 | communicate events via a callback mechanism. |
… | |
… | |
61 | You register interest in certain events by registering so-called I<event |
65 | You register interest in certain events by registering so-called I<event |
62 | watchers>, which are relatively small C structures you initialise with the |
66 | watchers>, which are relatively small C structures you initialise with the |
63 | details of the event, and then hand it over to libev by I<starting> the |
67 | details of the event, and then hand it over to libev by I<starting> the |
64 | watcher. |
68 | watcher. |
65 | |
69 | |
66 | =head1 FEATURES |
70 | =head2 FEATURES |
67 | |
71 | |
68 | Libev supports C<select>, C<poll>, the linux-specific C<epoll>, the |
72 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
69 | bsd-specific C<kqueue> and the solaris-specific event port mechanisms |
73 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
70 | for file descriptor events (C<ev_io>), relative timers (C<ev_timer>), |
74 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
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75 | (for C<ev_stat>), relative timers (C<ev_timer>), absolute timers |
71 | absolute timers with customised rescheduling (C<ev_periodic>), synchronous |
76 | with customised rescheduling (C<ev_periodic>), synchronous signals |
72 | signals (C<ev_signal>), process status change events (C<ev_child>), and |
77 | (C<ev_signal>), process status change events (C<ev_child>), and event |
73 | event watchers dealing with the event loop mechanism itself (C<ev_idle>, |
78 | watchers dealing with the event loop mechanism itself (C<ev_idle>, |
74 | C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as |
79 | C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as |
75 | file watchers (C<ev_stat>) and even limited support for fork events |
80 | file watchers (C<ev_stat>) and even limited support for fork events |
76 | (C<ev_fork>). |
81 | (C<ev_fork>). |
77 | |
82 | |
78 | It also is quite fast (see this |
83 | It also is quite fast (see this |
79 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
84 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
80 | for example). |
85 | for example). |
81 | |
86 | |
82 | =head1 CONVENTIONS |
87 | =head2 CONVENTIONS |
83 | |
88 | |
84 | Libev is very configurable. In this manual the default configuration will |
89 | Libev is very configurable. In this manual the default configuration will |
85 | be described, which supports multiple event loops. For more info about |
90 | be described, which supports multiple event loops. For more info about |
86 | various configuration options please have a look at B<EMBED> section in |
91 | various configuration options please have a look at B<EMBED> section in |
87 | this manual. If libev was configured without support for multiple event |
92 | this manual. If libev was configured without support for multiple event |
88 | loops, then all functions taking an initial argument of name C<loop> |
93 | loops, then all functions taking an initial argument of name C<loop> |
89 | (which is always of type C<struct ev_loop *>) will not have this argument. |
94 | (which is always of type C<struct ev_loop *>) will not have this argument. |
90 | |
95 | |
91 | =head1 TIME REPRESENTATION |
96 | =head2 TIME REPRESENTATION |
92 | |
97 | |
93 | Libev represents time as a single floating point number, representing the |
98 | Libev represents time as a single floating point number, representing the |
94 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
99 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
95 | the beginning of 1970, details are complicated, don't ask). This type is |
100 | the beginning of 1970, details are complicated, don't ask). This type is |
96 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
101 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
97 | to the C<double> type in C, and when you need to do any calculations on |
102 | to the C<double> type in C, and when you need to do any calculations on |
98 | it, you should treat it as such. |
103 | it, you should treat it as some floatingpoint value. Unlike the name |
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104 | component C<stamp> might indicate, it is also used for time differences |
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105 | throughout libev. |
99 | |
106 | |
100 | =head1 GLOBAL FUNCTIONS |
107 | =head1 GLOBAL FUNCTIONS |
101 | |
108 | |
102 | These functions can be called anytime, even before initialising the |
109 | These functions can be called anytime, even before initialising the |
103 | library in any way. |
110 | library in any way. |
… | |
… | |
108 | |
115 | |
109 | Returns the current time as libev would use it. Please note that the |
116 | Returns the current time as libev would use it. Please note that the |
110 | C<ev_now> function is usually faster and also often returns the timestamp |
117 | C<ev_now> function is usually faster and also often returns the timestamp |
111 | you actually want to know. |
118 | you actually want to know. |
112 | |
119 | |
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120 | =item ev_sleep (ev_tstamp interval) |
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121 | |
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122 | Sleep for the given interval: The current thread will be blocked until |
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123 | either it is interrupted or the given time interval has passed. Basically |
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124 | this is a subsecond-resolution C<sleep ()>. |
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125 | |
113 | =item int ev_version_major () |
126 | =item int ev_version_major () |
114 | |
127 | |
115 | =item int ev_version_minor () |
128 | =item int ev_version_minor () |
116 | |
129 | |
117 | You can find out the major and minor version numbers of the library |
130 | You can find out the major and minor ABI version numbers of the library |
118 | you linked against by calling the functions C<ev_version_major> and |
131 | you linked against by calling the functions C<ev_version_major> and |
119 | C<ev_version_minor>. If you want, you can compare against the global |
132 | C<ev_version_minor>. If you want, you can compare against the global |
120 | symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the |
133 | symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the |
121 | version of the library your program was compiled against. |
134 | version of the library your program was compiled against. |
122 | |
135 | |
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136 | These version numbers refer to the ABI version of the library, not the |
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137 | release version. |
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138 | |
123 | Usually, it's a good idea to terminate if the major versions mismatch, |
139 | Usually, it's a good idea to terminate if the major versions mismatch, |
124 | as this indicates an incompatible change. Minor versions are usually |
140 | as this indicates an incompatible change. Minor versions are usually |
125 | compatible to older versions, so a larger minor version alone is usually |
141 | compatible to older versions, so a larger minor version alone is usually |
126 | not a problem. |
142 | not a problem. |
127 | |
143 | |
128 | Example: Make sure we haven't accidentally been linked against the wrong |
144 | Example: Make sure we haven't accidentally been linked against the wrong |
129 | version. |
145 | version. |
… | |
… | |
162 | C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for |
178 | C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for |
163 | recommended ones. |
179 | recommended ones. |
164 | |
180 | |
165 | See the description of C<ev_embed> watchers for more info. |
181 | See the description of C<ev_embed> watchers for more info. |
166 | |
182 | |
167 | =item ev_set_allocator (void *(*cb)(void *ptr, size_t size)) |
183 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
168 | |
184 | |
169 | Sets the allocation function to use (the prototype and semantics are |
185 | Sets the allocation function to use (the prototype is similar - the |
170 | identical to the realloc C function). It is used to allocate and free |
186 | semantics is identical - to the realloc C function). It is used to |
171 | memory (no surprises here). If it returns zero when memory needs to be |
187 | allocate and free memory (no surprises here). If it returns zero when |
172 | allocated, the library might abort or take some potentially destructive |
188 | memory needs to be allocated, the library might abort or take some |
173 | action. The default is your system realloc function. |
189 | potentially destructive action. The default is your system realloc |
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190 | function. |
174 | |
191 | |
175 | You could override this function in high-availability programs to, say, |
192 | You could override this function in high-availability programs to, say, |
176 | free some memory if it cannot allocate memory, to use a special allocator, |
193 | free some memory if it cannot allocate memory, to use a special allocator, |
177 | or even to sleep a while and retry until some memory is available. |
194 | or even to sleep a while and retry until some memory is available. |
178 | |
195 | |
… | |
… | |
264 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
281 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
265 | override the flags completely if it is found in the environment. This is |
282 | override the flags completely if it is found in the environment. This is |
266 | useful to try out specific backends to test their performance, or to work |
283 | useful to try out specific backends to test their performance, or to work |
267 | around bugs. |
284 | around bugs. |
268 | |
285 | |
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286 | =item C<EVFLAG_FORKCHECK> |
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287 | |
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288 | Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after |
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289 | a fork, you can also make libev check for a fork in each iteration by |
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290 | enabling this flag. |
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291 | |
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292 | This works by calling C<getpid ()> on every iteration of the loop, |
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293 | and thus this might slow down your event loop if you do a lot of loop |
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294 | iterations and little real work, but is usually not noticeable (on my |
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295 | Linux system for example, C<getpid> is actually a simple 5-insn sequence |
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296 | without a syscall and thus I<very> fast, but my Linux system also has |
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297 | C<pthread_atfork> which is even faster). |
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298 | |
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299 | The big advantage of this flag is that you can forget about fork (and |
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300 | forget about forgetting to tell libev about forking) when you use this |
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301 | flag. |
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302 | |
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303 | This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS> |
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304 | environment variable. |
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305 | |
269 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
306 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
270 | |
307 | |
271 | This is your standard select(2) backend. Not I<completely> standard, as |
308 | This is your standard select(2) backend. Not I<completely> standard, as |
272 | libev tries to roll its own fd_set with no limits on the number of fds, |
309 | libev tries to roll its own fd_set with no limits on the number of fds, |
273 | but if that fails, expect a fairly low limit on the number of fds when |
310 | but if that fails, expect a fairly low limit on the number of fds when |
274 | using this backend. It doesn't scale too well (O(highest_fd)), but its usually |
311 | using this backend. It doesn't scale too well (O(highest_fd)), but its |
275 | the fastest backend for a low number of fds. |
312 | usually the fastest backend for a low number of (low-numbered :) fds. |
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313 | |
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314 | To get good performance out of this backend you need a high amount of |
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315 | parallelity (most of the file descriptors should be busy). If you are |
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316 | writing a server, you should C<accept ()> in a loop to accept as many |
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317 | connections as possible during one iteration. You might also want to have |
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318 | a look at C<ev_set_io_collect_interval ()> to increase the amount of |
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319 | readyness notifications you get per iteration. |
276 | |
320 | |
277 | =item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows) |
321 | =item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows) |
278 | |
322 | |
279 | And this is your standard poll(2) backend. It's more complicated than |
323 | And this is your standard poll(2) backend. It's more complicated |
280 | select, but handles sparse fds better and has no artificial limit on the |
324 | than select, but handles sparse fds better and has no artificial |
281 | number of fds you can use (except it will slow down considerably with a |
325 | limit on the number of fds you can use (except it will slow down |
282 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds). |
326 | considerably with a lot of inactive fds). It scales similarly to select, |
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327 | i.e. O(total_fds). See the entry for C<EVBACKEND_SELECT>, above, for |
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328 | performance tips. |
283 | |
329 | |
284 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
330 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
285 | |
331 | |
286 | For few fds, this backend is a bit little slower than poll and select, |
332 | For few fds, this backend is a bit little slower than poll and select, |
287 | but it scales phenomenally better. While poll and select usually scale like |
333 | but it scales phenomenally better. While poll and select usually scale |
288 | O(total_fds) where n is the total number of fds (or the highest fd), epoll scales |
334 | like O(total_fds) where n is the total number of fds (or the highest fd), |
289 | either O(1) or O(active_fds). |
335 | epoll scales either O(1) or O(active_fds). The epoll design has a number |
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336 | of shortcomings, such as silently dropping events in some hard-to-detect |
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337 | cases and rewiring a syscall per fd change, no fork support and bad |
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338 | support for dup. |
290 | |
339 | |
291 | While stopping and starting an I/O watcher in the same iteration will |
340 | While stopping, setting and starting an I/O watcher in the same iteration |
292 | result in some caching, there is still a syscall per such incident |
341 | will result in some caching, there is still a syscall per such incident |
293 | (because the fd could point to a different file description now), so its |
342 | (because the fd could point to a different file description now), so its |
294 | best to avoid that. Also, dup()ed file descriptors might not work very |
343 | best to avoid that. Also, C<dup ()>'ed file descriptors might not work |
295 | well if you register events for both fds. |
344 | very well if you register events for both fds. |
296 | |
345 | |
297 | Please note that epoll sometimes generates spurious notifications, so you |
346 | Please note that epoll sometimes generates spurious notifications, so you |
298 | need to use non-blocking I/O or other means to avoid blocking when no data |
347 | need to use non-blocking I/O or other means to avoid blocking when no data |
299 | (or space) is available. |
348 | (or space) is available. |
300 | |
349 | |
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350 | Best performance from this backend is achieved by not unregistering all |
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351 | watchers for a file descriptor until it has been closed, if possible, i.e. |
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352 | keep at least one watcher active per fd at all times. |
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353 | |
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354 | While nominally embeddeble in other event loops, this feature is broken in |
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355 | all kernel versions tested so far. |
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356 | |
301 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
357 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
302 | |
358 | |
303 | Kqueue deserves special mention, as at the time of this writing, it |
359 | Kqueue deserves special mention, as at the time of this writing, it |
304 | was broken on all BSDs except NetBSD (usually it doesn't work with |
360 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
305 | anything but sockets and pipes, except on Darwin, where of course its |
361 | with anything but sockets and pipes, except on Darwin, where of course |
306 | completely useless). For this reason its not being "autodetected" |
362 | it's completely useless). For this reason it's not being "autodetected" |
307 | unless you explicitly specify it explicitly in the flags (i.e. using |
363 | unless you explicitly specify it explicitly in the flags (i.e. using |
308 | C<EVBACKEND_KQUEUE>). |
364 | C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough) |
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365 | system like NetBSD. |
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366 | |
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367 | You still can embed kqueue into a normal poll or select backend and use it |
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368 | only for sockets (after having made sure that sockets work with kqueue on |
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369 | the target platform). See C<ev_embed> watchers for more info. |
309 | |
370 | |
310 | It scales in the same way as the epoll backend, but the interface to the |
371 | It scales in the same way as the epoll backend, but the interface to the |
311 | kernel is more efficient (which says nothing about its actual speed, of |
372 | kernel is more efficient (which says nothing about its actual speed, of |
312 | course). While starting and stopping an I/O watcher does not cause an |
373 | course). While stopping, setting and starting an I/O watcher does never |
313 | extra syscall as with epoll, it still adds up to four event changes per |
374 | cause an extra syscall as with C<EVBACKEND_EPOLL>, it still adds up to |
314 | incident, so its best to avoid that. |
375 | two event changes per incident, support for C<fork ()> is very bad and it |
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376 | drops fds silently in similarly hard-to-detect cases. |
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377 | |
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378 | This backend usually performs well under most conditions. |
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379 | |
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380 | While nominally embeddable in other event loops, this doesn't work |
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381 | everywhere, so you might need to test for this. And since it is broken |
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382 | almost everywhere, you should only use it when you have a lot of sockets |
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383 | (for which it usually works), by embedding it into another event loop |
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384 | (e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>) and using it only for |
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385 | sockets. |
315 | |
386 | |
316 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
387 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
317 | |
388 | |
318 | This is not implemented yet (and might never be). |
389 | This is not implemented yet (and might never be, unless you send me an |
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390 | implementation). According to reports, C</dev/poll> only supports sockets |
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391 | and is not embeddable, which would limit the usefulness of this backend |
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392 | immensely. |
319 | |
393 | |
320 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
394 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
321 | |
395 | |
322 | This uses the Solaris 10 port mechanism. As with everything on Solaris, |
396 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
323 | it's really slow, but it still scales very well (O(active_fds)). |
397 | it's really slow, but it still scales very well (O(active_fds)). |
324 | |
398 | |
325 | Please note that solaris ports can result in a lot of spurious |
399 | Please note that solaris event ports can deliver a lot of spurious |
326 | notifications, so you need to use non-blocking I/O or other means to avoid |
400 | notifications, so you need to use non-blocking I/O or other means to avoid |
327 | blocking when no data (or space) is available. |
401 | blocking when no data (or space) is available. |
|
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402 | |
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403 | While this backend scales well, it requires one system call per active |
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404 | file descriptor per loop iteration. For small and medium numbers of file |
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405 | descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend |
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406 | might perform better. |
328 | |
407 | |
329 | =item C<EVBACKEND_ALL> |
408 | =item C<EVBACKEND_ALL> |
330 | |
409 | |
331 | Try all backends (even potentially broken ones that wouldn't be tried |
410 | Try all backends (even potentially broken ones that wouldn't be tried |
332 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
411 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
333 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
412 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
|
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413 | |
|
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414 | It is definitely not recommended to use this flag. |
334 | |
415 | |
335 | =back |
416 | =back |
336 | |
417 | |
337 | If one or more of these are ored into the flags value, then only these |
418 | If one or more of these are ored into the flags value, then only these |
338 | backends will be tried (in the reverse order as given here). If none are |
419 | backends will be tried (in the reverse order as given here). If none are |
… | |
… | |
373 | Destroys the default loop again (frees all memory and kernel state |
454 | Destroys the default loop again (frees all memory and kernel state |
374 | etc.). None of the active event watchers will be stopped in the normal |
455 | etc.). None of the active event watchers will be stopped in the normal |
375 | sense, so e.g. C<ev_is_active> might still return true. It is your |
456 | sense, so e.g. C<ev_is_active> might still return true. It is your |
376 | responsibility to either stop all watchers cleanly yoursef I<before> |
457 | responsibility to either stop all watchers cleanly yoursef I<before> |
377 | calling this function, or cope with the fact afterwards (which is usually |
458 | calling this function, or cope with the fact afterwards (which is usually |
378 | the easiest thing, youc na just ignore the watchers and/or C<free ()> them |
459 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
379 | for example). |
460 | for example). |
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461 | |
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462 | Note that certain global state, such as signal state, will not be freed by |
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463 | this function, and related watchers (such as signal and child watchers) |
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464 | would need to be stopped manually. |
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465 | |
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466 | In general it is not advisable to call this function except in the |
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467 | rare occasion where you really need to free e.g. the signal handling |
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468 | pipe fds. If you need dynamically allocated loops it is better to use |
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469 | C<ev_loop_new> and C<ev_loop_destroy>). |
380 | |
470 | |
381 | =item ev_loop_destroy (loop) |
471 | =item ev_loop_destroy (loop) |
382 | |
472 | |
383 | Like C<ev_default_destroy>, but destroys an event loop created by an |
473 | Like C<ev_default_destroy>, but destroys an event loop created by an |
384 | earlier call to C<ev_loop_new>. |
474 | earlier call to C<ev_loop_new>. |
… | |
… | |
408 | |
498 | |
409 | Like C<ev_default_fork>, but acts on an event loop created by |
499 | Like C<ev_default_fork>, but acts on an event loop created by |
410 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
500 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
411 | after fork, and how you do this is entirely your own problem. |
501 | after fork, and how you do this is entirely your own problem. |
412 | |
502 | |
|
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503 | =item unsigned int ev_loop_count (loop) |
|
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504 | |
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505 | Returns the count of loop iterations for the loop, which is identical to |
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506 | the number of times libev did poll for new events. It starts at C<0> and |
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|
507 | happily wraps around with enough iterations. |
|
|
508 | |
|
|
509 | This value can sometimes be useful as a generation counter of sorts (it |
|
|
510 | "ticks" the number of loop iterations), as it roughly corresponds with |
|
|
511 | C<ev_prepare> and C<ev_check> calls. |
|
|
512 | |
413 | =item unsigned int ev_backend (loop) |
513 | =item unsigned int ev_backend (loop) |
414 | |
514 | |
415 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
515 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
416 | use. |
516 | use. |
417 | |
517 | |
… | |
… | |
419 | |
519 | |
420 | Returns the current "event loop time", which is the time the event loop |
520 | Returns the current "event loop time", which is the time the event loop |
421 | received events and started processing them. This timestamp does not |
521 | received events and started processing them. This timestamp does not |
422 | change as long as callbacks are being processed, and this is also the base |
522 | change as long as callbacks are being processed, and this is also the base |
423 | time used for relative timers. You can treat it as the timestamp of the |
523 | time used for relative timers. You can treat it as the timestamp of the |
424 | event occuring (or more correctly, libev finding out about it). |
524 | event occurring (or more correctly, libev finding out about it). |
425 | |
525 | |
426 | =item ev_loop (loop, int flags) |
526 | =item ev_loop (loop, int flags) |
427 | |
527 | |
428 | Finally, this is it, the event handler. This function usually is called |
528 | Finally, this is it, the event handler. This function usually is called |
429 | after you initialised all your watchers and you want to start handling |
529 | after you initialised all your watchers and you want to start handling |
… | |
… | |
450 | libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is |
550 | libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is |
451 | usually a better approach for this kind of thing. |
551 | usually a better approach for this kind of thing. |
452 | |
552 | |
453 | Here are the gory details of what C<ev_loop> does: |
553 | Here are the gory details of what C<ev_loop> does: |
454 | |
554 | |
|
|
555 | - Before the first iteration, call any pending watchers. |
455 | * If there are no active watchers (reference count is zero), return. |
556 | * If there are no active watchers (reference count is zero), return. |
456 | - Queue prepare watchers and then call all outstanding watchers. |
557 | - Queue all prepare watchers and then call all outstanding watchers. |
457 | - If we have been forked, recreate the kernel state. |
558 | - If we have been forked, recreate the kernel state. |
458 | - Update the kernel state with all outstanding changes. |
559 | - Update the kernel state with all outstanding changes. |
459 | - Update the "event loop time". |
560 | - Update the "event loop time". |
460 | - Calculate for how long to block. |
561 | - Calculate for how long to block. |
461 | - Block the process, waiting for any events. |
562 | - Block the process, waiting for any events. |
… | |
… | |
512 | Example: For some weird reason, unregister the above signal handler again. |
613 | Example: For some weird reason, unregister the above signal handler again. |
513 | |
614 | |
514 | ev_ref (loop); |
615 | ev_ref (loop); |
515 | ev_signal_stop (loop, &exitsig); |
616 | ev_signal_stop (loop, &exitsig); |
516 | |
617 | |
|
|
618 | =item ev_set_io_collect_interval (loop, ev_tstamp interval) |
|
|
619 | |
|
|
620 | =item ev_set_timeout_collect_interval (loop, ev_tstamp interval) |
|
|
621 | |
|
|
622 | These advanced functions influence the time that libev will spend waiting |
|
|
623 | for events. Both are by default C<0>, meaning that libev will try to |
|
|
624 | invoke timer/periodic callbacks and I/O callbacks with minimum latency. |
|
|
625 | |
|
|
626 | Setting these to a higher value (the C<interval> I<must> be >= C<0>) |
|
|
627 | allows libev to delay invocation of I/O and timer/periodic callbacks to |
|
|
628 | increase efficiency of loop iterations. |
|
|
629 | |
|
|
630 | The background is that sometimes your program runs just fast enough to |
|
|
631 | handle one (or very few) event(s) per loop iteration. While this makes |
|
|
632 | the program responsive, it also wastes a lot of CPU time to poll for new |
|
|
633 | events, especially with backends like C<select ()> which have a high |
|
|
634 | overhead for the actual polling but can deliver many events at once. |
|
|
635 | |
|
|
636 | By setting a higher I<io collect interval> you allow libev to spend more |
|
|
637 | time collecting I/O events, so you can handle more events per iteration, |
|
|
638 | at the cost of increasing latency. Timeouts (both C<ev_periodic> and |
|
|
639 | C<ev_timer>) will be not affected. Setting this to a non-null value will |
|
|
640 | introduce an additional C<ev_sleep ()> call into most loop iterations. |
|
|
641 | |
|
|
642 | Likewise, by setting a higher I<timeout collect interval> you allow libev |
|
|
643 | to spend more time collecting timeouts, at the expense of increased |
|
|
644 | latency (the watcher callback will be called later). C<ev_io> watchers |
|
|
645 | will not be affected. Setting this to a non-null value will not introduce |
|
|
646 | any overhead in libev. |
|
|
647 | |
|
|
648 | Many (busy) programs can usually benefit by setting the io collect |
|
|
649 | interval to a value near C<0.1> or so, which is often enough for |
|
|
650 | interactive servers (of course not for games), likewise for timeouts. It |
|
|
651 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
|
|
652 | as this approsaches the timing granularity of most systems. |
|
|
653 | |
517 | =back |
654 | =back |
518 | |
655 | |
519 | |
656 | |
520 | =head1 ANATOMY OF A WATCHER |
657 | =head1 ANATOMY OF A WATCHER |
521 | |
658 | |
… | |
… | |
700 | =item bool ev_is_pending (ev_TYPE *watcher) |
837 | =item bool ev_is_pending (ev_TYPE *watcher) |
701 | |
838 | |
702 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
839 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
703 | events but its callback has not yet been invoked). As long as a watcher |
840 | events but its callback has not yet been invoked). As long as a watcher |
704 | is pending (but not active) you must not call an init function on it (but |
841 | is pending (but not active) you must not call an init function on it (but |
705 | C<ev_TYPE_set> is safe) and you must make sure the watcher is available to |
842 | C<ev_TYPE_set> is safe), you must not change its priority, and you must |
706 | libev (e.g. you cnanot C<free ()> it). |
843 | make sure the watcher is available to libev (e.g. you cannot C<free ()> |
|
|
844 | it). |
707 | |
845 | |
708 | =item callback = ev_cb (ev_TYPE *watcher) |
846 | =item callback ev_cb (ev_TYPE *watcher) |
709 | |
847 | |
710 | Returns the callback currently set on the watcher. |
848 | Returns the callback currently set on the watcher. |
711 | |
849 | |
712 | =item ev_cb_set (ev_TYPE *watcher, callback) |
850 | =item ev_cb_set (ev_TYPE *watcher, callback) |
713 | |
851 | |
714 | Change the callback. You can change the callback at virtually any time |
852 | Change the callback. You can change the callback at virtually any time |
715 | (modulo threads). |
853 | (modulo threads). |
|
|
854 | |
|
|
855 | =item ev_set_priority (ev_TYPE *watcher, priority) |
|
|
856 | |
|
|
857 | =item int ev_priority (ev_TYPE *watcher) |
|
|
858 | |
|
|
859 | Set and query the priority of the watcher. The priority is a small |
|
|
860 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
|
|
861 | (default: C<-2>). Pending watchers with higher priority will be invoked |
|
|
862 | before watchers with lower priority, but priority will not keep watchers |
|
|
863 | from being executed (except for C<ev_idle> watchers). |
|
|
864 | |
|
|
865 | This means that priorities are I<only> used for ordering callback |
|
|
866 | invocation after new events have been received. This is useful, for |
|
|
867 | example, to reduce latency after idling, or more often, to bind two |
|
|
868 | watchers on the same event and make sure one is called first. |
|
|
869 | |
|
|
870 | If you need to suppress invocation when higher priority events are pending |
|
|
871 | you need to look at C<ev_idle> watchers, which provide this functionality. |
|
|
872 | |
|
|
873 | You I<must not> change the priority of a watcher as long as it is active or |
|
|
874 | pending. |
|
|
875 | |
|
|
876 | The default priority used by watchers when no priority has been set is |
|
|
877 | always C<0>, which is supposed to not be too high and not be too low :). |
|
|
878 | |
|
|
879 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
|
|
880 | fine, as long as you do not mind that the priority value you query might |
|
|
881 | or might not have been adjusted to be within valid range. |
|
|
882 | |
|
|
883 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
|
|
884 | |
|
|
885 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
|
|
886 | C<loop> nor C<revents> need to be valid as long as the watcher callback |
|
|
887 | can deal with that fact. |
|
|
888 | |
|
|
889 | =item int ev_clear_pending (loop, ev_TYPE *watcher) |
|
|
890 | |
|
|
891 | If the watcher is pending, this function returns clears its pending status |
|
|
892 | and returns its C<revents> bitset (as if its callback was invoked). If the |
|
|
893 | watcher isn't pending it does nothing and returns C<0>. |
716 | |
894 | |
717 | =back |
895 | =back |
718 | |
896 | |
719 | |
897 | |
720 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
898 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
… | |
… | |
741 | { |
919 | { |
742 | struct my_io *w = (struct my_io *)w_; |
920 | struct my_io *w = (struct my_io *)w_; |
743 | ... |
921 | ... |
744 | } |
922 | } |
745 | |
923 | |
746 | More interesting and less C-conformant ways of catsing your callback type |
924 | More interesting and less C-conformant ways of casting your callback type |
747 | have been omitted.... |
925 | instead have been omitted. |
|
|
926 | |
|
|
927 | Another common scenario is having some data structure with multiple |
|
|
928 | watchers: |
|
|
929 | |
|
|
930 | struct my_biggy |
|
|
931 | { |
|
|
932 | int some_data; |
|
|
933 | ev_timer t1; |
|
|
934 | ev_timer t2; |
|
|
935 | } |
|
|
936 | |
|
|
937 | In this case getting the pointer to C<my_biggy> is a bit more complicated, |
|
|
938 | you need to use C<offsetof>: |
|
|
939 | |
|
|
940 | #include <stddef.h> |
|
|
941 | |
|
|
942 | static void |
|
|
943 | t1_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
944 | { |
|
|
945 | struct my_biggy big = (struct my_biggy * |
|
|
946 | (((char *)w) - offsetof (struct my_biggy, t1)); |
|
|
947 | } |
|
|
948 | |
|
|
949 | static void |
|
|
950 | t2_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
951 | { |
|
|
952 | struct my_biggy big = (struct my_biggy * |
|
|
953 | (((char *)w) - offsetof (struct my_biggy, t2)); |
|
|
954 | } |
748 | |
955 | |
749 | |
956 | |
750 | =head1 WATCHER TYPES |
957 | =head1 WATCHER TYPES |
751 | |
958 | |
752 | This section describes each watcher in detail, but will not repeat |
959 | This section describes each watcher in detail, but will not repeat |
… | |
… | |
776 | In general you can register as many read and/or write event watchers per |
983 | In general you can register as many read and/or write event watchers per |
777 | fd as you want (as long as you don't confuse yourself). Setting all file |
984 | fd as you want (as long as you don't confuse yourself). Setting all file |
778 | descriptors to non-blocking mode is also usually a good idea (but not |
985 | descriptors to non-blocking mode is also usually a good idea (but not |
779 | required if you know what you are doing). |
986 | required if you know what you are doing). |
780 | |
987 | |
781 | You have to be careful with dup'ed file descriptors, though. Some backends |
|
|
782 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
|
|
783 | descriptors correctly if you register interest in two or more fds pointing |
|
|
784 | to the same underlying file/socket/etc. description (that is, they share |
|
|
785 | the same underlying "file open"). |
|
|
786 | |
|
|
787 | If you must do this, then force the use of a known-to-be-good backend |
988 | If you must do this, then force the use of a known-to-be-good backend |
788 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
989 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
789 | C<EVBACKEND_POLL>). |
990 | C<EVBACKEND_POLL>). |
790 | |
991 | |
791 | Another thing you have to watch out for is that it is quite easy to |
992 | Another thing you have to watch out for is that it is quite easy to |
… | |
… | |
797 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
998 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
798 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
999 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
799 | |
1000 | |
800 | If you cannot run the fd in non-blocking mode (for example you should not |
1001 | If you cannot run the fd in non-blocking mode (for example you should not |
801 | play around with an Xlib connection), then you have to seperately re-test |
1002 | play around with an Xlib connection), then you have to seperately re-test |
802 | wether a file descriptor is really ready with a known-to-be good interface |
1003 | whether a file descriptor is really ready with a known-to-be good interface |
803 | such as poll (fortunately in our Xlib example, Xlib already does this on |
1004 | such as poll (fortunately in our Xlib example, Xlib already does this on |
804 | its own, so its quite safe to use). |
1005 | its own, so its quite safe to use). |
|
|
1006 | |
|
|
1007 | =head3 The special problem of disappearing file descriptors |
|
|
1008 | |
|
|
1009 | Some backends (e.g. kqueue, epoll) need to be told about closing a file |
|
|
1010 | descriptor (either by calling C<close> explicitly or by any other means, |
|
|
1011 | such as C<dup>). The reason is that you register interest in some file |
|
|
1012 | descriptor, but when it goes away, the operating system will silently drop |
|
|
1013 | this interest. If another file descriptor with the same number then is |
|
|
1014 | registered with libev, there is no efficient way to see that this is, in |
|
|
1015 | fact, a different file descriptor. |
|
|
1016 | |
|
|
1017 | To avoid having to explicitly tell libev about such cases, libev follows |
|
|
1018 | the following policy: Each time C<ev_io_set> is being called, libev |
|
|
1019 | will assume that this is potentially a new file descriptor, otherwise |
|
|
1020 | it is assumed that the file descriptor stays the same. That means that |
|
|
1021 | you I<have> to call C<ev_io_set> (or C<ev_io_init>) when you change the |
|
|
1022 | descriptor even if the file descriptor number itself did not change. |
|
|
1023 | |
|
|
1024 | This is how one would do it normally anyway, the important point is that |
|
|
1025 | the libev application should not optimise around libev but should leave |
|
|
1026 | optimisations to libev. |
|
|
1027 | |
|
|
1028 | =head3 The special problem of dup'ed file descriptors |
|
|
1029 | |
|
|
1030 | Some backends (e.g. epoll), cannot register events for file descriptors, |
|
|
1031 | but only events for the underlying file descriptions. That means when you |
|
|
1032 | have C<dup ()>'ed file descriptors or weirder constellations, and register |
|
|
1033 | events for them, only one file descriptor might actually receive events. |
|
|
1034 | |
|
|
1035 | There is no workaround possible except not registering events |
|
|
1036 | for potentially C<dup ()>'ed file descriptors, or to resort to |
|
|
1037 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
|
|
1038 | |
|
|
1039 | =head3 The special problem of fork |
|
|
1040 | |
|
|
1041 | Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit |
|
|
1042 | useless behaviour. Libev fully supports fork, but needs to be told about |
|
|
1043 | it in the child. |
|
|
1044 | |
|
|
1045 | To support fork in your programs, you either have to call |
|
|
1046 | C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child, |
|
|
1047 | enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or |
|
|
1048 | C<EVBACKEND_POLL>. |
|
|
1049 | |
|
|
1050 | |
|
|
1051 | =head3 Watcher-Specific Functions |
805 | |
1052 | |
806 | =over 4 |
1053 | =over 4 |
807 | |
1054 | |
808 | =item ev_io_init (ev_io *, callback, int fd, int events) |
1055 | =item ev_io_init (ev_io *, callback, int fd, int events) |
809 | |
1056 | |
… | |
… | |
863 | |
1110 | |
864 | The callback is guarenteed to be invoked only when its timeout has passed, |
1111 | The callback is guarenteed to be invoked only when its timeout has passed, |
865 | but if multiple timers become ready during the same loop iteration then |
1112 | but if multiple timers become ready during the same loop iteration then |
866 | order of execution is undefined. |
1113 | order of execution is undefined. |
867 | |
1114 | |
|
|
1115 | =head3 Watcher-Specific Functions and Data Members |
|
|
1116 | |
868 | =over 4 |
1117 | =over 4 |
869 | |
1118 | |
870 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
1119 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
871 | |
1120 | |
872 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
1121 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
… | |
… | |
885 | =item ev_timer_again (loop) |
1134 | =item ev_timer_again (loop) |
886 | |
1135 | |
887 | This will act as if the timer timed out and restart it again if it is |
1136 | This will act as if the timer timed out and restart it again if it is |
888 | repeating. The exact semantics are: |
1137 | repeating. The exact semantics are: |
889 | |
1138 | |
|
|
1139 | If the timer is pending, its pending status is cleared. |
|
|
1140 | |
890 | If the timer is started but nonrepeating, stop it. |
1141 | If the timer is started but nonrepeating, stop it (as if it timed out). |
891 | |
1142 | |
892 | If the timer is repeating, either start it if necessary (with the repeat |
1143 | If the timer is repeating, either start it if necessary (with the |
893 | value), or reset the running timer to the repeat value. |
1144 | C<repeat> value), or reset the running timer to the C<repeat> value. |
894 | |
1145 | |
895 | This sounds a bit complicated, but here is a useful and typical |
1146 | This sounds a bit complicated, but here is a useful and typical |
896 | example: Imagine you have a tcp connection and you want a so-called |
1147 | example: Imagine you have a tcp connection and you want a so-called idle |
897 | idle timeout, that is, you want to be called when there have been, |
1148 | timeout, that is, you want to be called when there have been, say, 60 |
898 | say, 60 seconds of inactivity on the socket. The easiest way to do |
1149 | seconds of inactivity on the socket. The easiest way to do this is to |
899 | this is to configure an C<ev_timer> with C<after>=C<repeat>=C<60> and calling |
1150 | configure an C<ev_timer> with a C<repeat> value of C<60> and then call |
900 | C<ev_timer_again> each time you successfully read or write some data. If |
1151 | C<ev_timer_again> each time you successfully read or write some data. If |
901 | you go into an idle state where you do not expect data to travel on the |
1152 | you go into an idle state where you do not expect data to travel on the |
902 | socket, you can stop the timer, and again will automatically restart it if |
1153 | socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will |
903 | need be. |
1154 | automatically restart it if need be. |
904 | |
1155 | |
905 | You can also ignore the C<after> value and C<ev_timer_start> altogether |
1156 | That means you can ignore the C<after> value and C<ev_timer_start> |
906 | and only ever use the C<repeat> value: |
1157 | altogether and only ever use the C<repeat> value and C<ev_timer_again>: |
907 | |
1158 | |
908 | ev_timer_init (timer, callback, 0., 5.); |
1159 | ev_timer_init (timer, callback, 0., 5.); |
909 | ev_timer_again (loop, timer); |
1160 | ev_timer_again (loop, timer); |
910 | ... |
1161 | ... |
911 | timer->again = 17.; |
1162 | timer->again = 17.; |
912 | ev_timer_again (loop, timer); |
1163 | ev_timer_again (loop, timer); |
913 | ... |
1164 | ... |
914 | timer->again = 10.; |
1165 | timer->again = 10.; |
915 | ev_timer_again (loop, timer); |
1166 | ev_timer_again (loop, timer); |
916 | |
1167 | |
917 | This is more efficient then stopping/starting the timer eahc time you want |
1168 | This is more slightly efficient then stopping/starting the timer each time |
918 | to modify its timeout value. |
1169 | you want to modify its timeout value. |
919 | |
1170 | |
920 | =item ev_tstamp repeat [read-write] |
1171 | =item ev_tstamp repeat [read-write] |
921 | |
1172 | |
922 | The current C<repeat> value. Will be used each time the watcher times out |
1173 | The current C<repeat> value. Will be used each time the watcher times out |
923 | or C<ev_timer_again> is called and determines the next timeout (if any), |
1174 | or C<ev_timer_again> is called and determines the next timeout (if any), |
… | |
… | |
965 | but on wallclock time (absolute time). You can tell a periodic watcher |
1216 | but on wallclock time (absolute time). You can tell a periodic watcher |
966 | to trigger "at" some specific point in time. For example, if you tell a |
1217 | to trigger "at" some specific point in time. For example, if you tell a |
967 | periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now () |
1218 | periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now () |
968 | + 10.>) and then reset your system clock to the last year, then it will |
1219 | + 10.>) and then reset your system clock to the last year, then it will |
969 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
1220 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
970 | roughly 10 seconds later and of course not if you reset your system time |
1221 | roughly 10 seconds later). |
971 | again). |
|
|
972 | |
1222 | |
973 | They can also be used to implement vastly more complex timers, such as |
1223 | They can also be used to implement vastly more complex timers, such as |
974 | triggering an event on eahc midnight, local time. |
1224 | triggering an event on each midnight, local time or other, complicated, |
|
|
1225 | rules. |
975 | |
1226 | |
976 | As with timers, the callback is guarenteed to be invoked only when the |
1227 | As with timers, the callback is guarenteed to be invoked only when the |
977 | time (C<at>) has been passed, but if multiple periodic timers become ready |
1228 | time (C<at>) has been passed, but if multiple periodic timers become ready |
978 | during the same loop iteration then order of execution is undefined. |
1229 | during the same loop iteration then order of execution is undefined. |
979 | |
1230 | |
|
|
1231 | =head3 Watcher-Specific Functions and Data Members |
|
|
1232 | |
980 | =over 4 |
1233 | =over 4 |
981 | |
1234 | |
982 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
1235 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
983 | |
1236 | |
984 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
1237 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
… | |
… | |
986 | Lots of arguments, lets sort it out... There are basically three modes of |
1239 | Lots of arguments, lets sort it out... There are basically three modes of |
987 | operation, and we will explain them from simplest to complex: |
1240 | operation, and we will explain them from simplest to complex: |
988 | |
1241 | |
989 | =over 4 |
1242 | =over 4 |
990 | |
1243 | |
991 | =item * absolute timer (interval = reschedule_cb = 0) |
1244 | =item * absolute timer (at = time, interval = reschedule_cb = 0) |
992 | |
1245 | |
993 | In this configuration the watcher triggers an event at the wallclock time |
1246 | In this configuration the watcher triggers an event at the wallclock time |
994 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
1247 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
995 | that is, if it is to be run at January 1st 2011 then it will run when the |
1248 | that is, if it is to be run at January 1st 2011 then it will run when the |
996 | system time reaches or surpasses this time. |
1249 | system time reaches or surpasses this time. |
997 | |
1250 | |
998 | =item * non-repeating interval timer (interval > 0, reschedule_cb = 0) |
1251 | =item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
999 | |
1252 | |
1000 | In this mode the watcher will always be scheduled to time out at the next |
1253 | In this mode the watcher will always be scheduled to time out at the next |
1001 | C<at + N * interval> time (for some integer N) and then repeat, regardless |
1254 | C<at + N * interval> time (for some integer N, which can also be negative) |
1002 | of any time jumps. |
1255 | and then repeat, regardless of any time jumps. |
1003 | |
1256 | |
1004 | This can be used to create timers that do not drift with respect to system |
1257 | This can be used to create timers that do not drift with respect to system |
1005 | time: |
1258 | time: |
1006 | |
1259 | |
1007 | ev_periodic_set (&periodic, 0., 3600., 0); |
1260 | ev_periodic_set (&periodic, 0., 3600., 0); |
… | |
… | |
1013 | |
1266 | |
1014 | Another way to think about it (for the mathematically inclined) is that |
1267 | Another way to think about it (for the mathematically inclined) is that |
1015 | C<ev_periodic> will try to run the callback in this mode at the next possible |
1268 | C<ev_periodic> will try to run the callback in this mode at the next possible |
1016 | time where C<time = at (mod interval)>, regardless of any time jumps. |
1269 | time where C<time = at (mod interval)>, regardless of any time jumps. |
1017 | |
1270 | |
|
|
1271 | For numerical stability it is preferable that the C<at> value is near |
|
|
1272 | C<ev_now ()> (the current time), but there is no range requirement for |
|
|
1273 | this value. |
|
|
1274 | |
1018 | =item * manual reschedule mode (reschedule_cb = callback) |
1275 | =item * manual reschedule mode (at and interval ignored, reschedule_cb = callback) |
1019 | |
1276 | |
1020 | In this mode the values for C<interval> and C<at> are both being |
1277 | In this mode the values for C<interval> and C<at> are both being |
1021 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1278 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1022 | reschedule callback will be called with the watcher as first, and the |
1279 | reschedule callback will be called with the watcher as first, and the |
1023 | current time as second argument. |
1280 | current time as second argument. |
1024 | |
1281 | |
1025 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
1282 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
1026 | ever, or make any event loop modifications>. If you need to stop it, |
1283 | ever, or make any event loop modifications>. If you need to stop it, |
1027 | return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by |
1284 | return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by |
1028 | starting a prepare watcher). |
1285 | starting an C<ev_prepare> watcher, which is legal). |
1029 | |
1286 | |
1030 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1287 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1031 | ev_tstamp now)>, e.g.: |
1288 | ev_tstamp now)>, e.g.: |
1032 | |
1289 | |
1033 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
1290 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
… | |
… | |
1056 | Simply stops and restarts the periodic watcher again. This is only useful |
1313 | Simply stops and restarts the periodic watcher again. This is only useful |
1057 | when you changed some parameters or the reschedule callback would return |
1314 | when you changed some parameters or the reschedule callback would return |
1058 | a different time than the last time it was called (e.g. in a crond like |
1315 | a different time than the last time it was called (e.g. in a crond like |
1059 | program when the crontabs have changed). |
1316 | program when the crontabs have changed). |
1060 | |
1317 | |
|
|
1318 | =item ev_tstamp offset [read-write] |
|
|
1319 | |
|
|
1320 | When repeating, this contains the offset value, otherwise this is the |
|
|
1321 | absolute point in time (the C<at> value passed to C<ev_periodic_set>). |
|
|
1322 | |
|
|
1323 | Can be modified any time, but changes only take effect when the periodic |
|
|
1324 | timer fires or C<ev_periodic_again> is being called. |
|
|
1325 | |
1061 | =item ev_tstamp interval [read-write] |
1326 | =item ev_tstamp interval [read-write] |
1062 | |
1327 | |
1063 | The current interval value. Can be modified any time, but changes only |
1328 | The current interval value. Can be modified any time, but changes only |
1064 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
1329 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
1065 | called. |
1330 | called. |
… | |
… | |
1067 | =item ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write] |
1332 | =item ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write] |
1068 | |
1333 | |
1069 | The current reschedule callback, or C<0>, if this functionality is |
1334 | The current reschedule callback, or C<0>, if this functionality is |
1070 | switched off. Can be changed any time, but changes only take effect when |
1335 | switched off. Can be changed any time, but changes only take effect when |
1071 | the periodic timer fires or C<ev_periodic_again> is being called. |
1336 | the periodic timer fires or C<ev_periodic_again> is being called. |
|
|
1337 | |
|
|
1338 | =item ev_tstamp at [read-only] |
|
|
1339 | |
|
|
1340 | When active, contains the absolute time that the watcher is supposed to |
|
|
1341 | trigger next. |
1072 | |
1342 | |
1073 | =back |
1343 | =back |
1074 | |
1344 | |
1075 | Example: Call a callback every hour, or, more precisely, whenever the |
1345 | Example: Call a callback every hour, or, more precisely, whenever the |
1076 | system clock is divisible by 3600. The callback invocation times have |
1346 | system clock is divisible by 3600. The callback invocation times have |
… | |
… | |
1118 | with the kernel (thus it coexists with your own signal handlers as long |
1388 | with the kernel (thus it coexists with your own signal handlers as long |
1119 | as you don't register any with libev). Similarly, when the last signal |
1389 | as you don't register any with libev). Similarly, when the last signal |
1120 | watcher for a signal is stopped libev will reset the signal handler to |
1390 | watcher for a signal is stopped libev will reset the signal handler to |
1121 | SIG_DFL (regardless of what it was set to before). |
1391 | SIG_DFL (regardless of what it was set to before). |
1122 | |
1392 | |
|
|
1393 | =head3 Watcher-Specific Functions and Data Members |
|
|
1394 | |
1123 | =over 4 |
1395 | =over 4 |
1124 | |
1396 | |
1125 | =item ev_signal_init (ev_signal *, callback, int signum) |
1397 | =item ev_signal_init (ev_signal *, callback, int signum) |
1126 | |
1398 | |
1127 | =item ev_signal_set (ev_signal *, int signum) |
1399 | =item ev_signal_set (ev_signal *, int signum) |
… | |
… | |
1138 | |
1410 | |
1139 | =head2 C<ev_child> - watch out for process status changes |
1411 | =head2 C<ev_child> - watch out for process status changes |
1140 | |
1412 | |
1141 | Child watchers trigger when your process receives a SIGCHLD in response to |
1413 | Child watchers trigger when your process receives a SIGCHLD in response to |
1142 | some child status changes (most typically when a child of yours dies). |
1414 | some child status changes (most typically when a child of yours dies). |
|
|
1415 | |
|
|
1416 | =head3 Watcher-Specific Functions and Data Members |
1143 | |
1417 | |
1144 | =over 4 |
1418 | =over 4 |
1145 | |
1419 | |
1146 | =item ev_child_init (ev_child *, callback, int pid) |
1420 | =item ev_child_init (ev_child *, callback, int pid) |
1147 | |
1421 | |
… | |
… | |
1192 | not exist" is a status change like any other. The condition "path does |
1466 | not exist" is a status change like any other. The condition "path does |
1193 | not exist" is signified by the C<st_nlink> field being zero (which is |
1467 | not exist" is signified by the C<st_nlink> field being zero (which is |
1194 | otherwise always forced to be at least one) and all the other fields of |
1468 | otherwise always forced to be at least one) and all the other fields of |
1195 | the stat buffer having unspecified contents. |
1469 | the stat buffer having unspecified contents. |
1196 | |
1470 | |
|
|
1471 | The path I<should> be absolute and I<must not> end in a slash. If it is |
|
|
1472 | relative and your working directory changes, the behaviour is undefined. |
|
|
1473 | |
1197 | Since there is no standard to do this, the portable implementation simply |
1474 | Since there is no standard to do this, the portable implementation simply |
1198 | calls C<stat (2)> regulalry on the path to see if it changed somehow. You |
1475 | calls C<stat (2)> regularly on the path to see if it changed somehow. You |
1199 | can specify a recommended polling interval for this case. If you specify |
1476 | can specify a recommended polling interval for this case. If you specify |
1200 | a polling interval of C<0> (highly recommended!) then a I<suitable, |
1477 | a polling interval of C<0> (highly recommended!) then a I<suitable, |
1201 | unspecified default> value will be used (which you can expect to be around |
1478 | unspecified default> value will be used (which you can expect to be around |
1202 | five seconds, although this might change dynamically). Libev will also |
1479 | five seconds, although this might change dynamically). Libev will also |
1203 | impose a minimum interval which is currently around C<0.1>, but thats |
1480 | impose a minimum interval which is currently around C<0.1>, but thats |
… | |
… | |
1205 | |
1482 | |
1206 | This watcher type is not meant for massive numbers of stat watchers, |
1483 | This watcher type is not meant for massive numbers of stat watchers, |
1207 | as even with OS-supported change notifications, this can be |
1484 | as even with OS-supported change notifications, this can be |
1208 | resource-intensive. |
1485 | resource-intensive. |
1209 | |
1486 | |
1210 | At the time of this writing, no specific OS backends are implemented, but |
1487 | At the time of this writing, only the Linux inotify interface is |
1211 | if demand increases, at least a kqueue and inotify backend will be added. |
1488 | implemented (implementing kqueue support is left as an exercise for the |
|
|
1489 | reader). Inotify will be used to give hints only and should not change the |
|
|
1490 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
|
|
1491 | to fall back to regular polling again even with inotify, but changes are |
|
|
1492 | usually detected immediately, and if the file exists there will be no |
|
|
1493 | polling. |
|
|
1494 | |
|
|
1495 | =head3 Inotify |
|
|
1496 | |
|
|
1497 | When C<inotify (7)> support has been compiled into libev (generally only |
|
|
1498 | available on Linux) and present at runtime, it will be used to speed up |
|
|
1499 | change detection where possible. The inotify descriptor will be created lazily |
|
|
1500 | when the first C<ev_stat> watcher is being started. |
|
|
1501 | |
|
|
1502 | Inotify presense does not change the semantics of C<ev_stat> watchers |
|
|
1503 | except that changes might be detected earlier, and in some cases, to avoid |
|
|
1504 | making regular C<stat> calls. Even in the presense of inotify support |
|
|
1505 | there are many cases where libev has to resort to regular C<stat> polling. |
|
|
1506 | |
|
|
1507 | (There is no support for kqueue, as apparently it cannot be used to |
|
|
1508 | implement this functionality, due to the requirement of having a file |
|
|
1509 | descriptor open on the object at all times). |
|
|
1510 | |
|
|
1511 | =head3 The special problem of stat time resolution |
|
|
1512 | |
|
|
1513 | The C<stat ()> syscall only supports full-second resolution portably, and |
|
|
1514 | even on systems where the resolution is higher, many filesystems still |
|
|
1515 | only support whole seconds. |
|
|
1516 | |
|
|
1517 | That means that, if the time is the only thing that changes, you might |
|
|
1518 | miss updates: on the first update, C<ev_stat> detects a change and calls |
|
|
1519 | your callback, which does something. When there is another update within |
|
|
1520 | the same second, C<ev_stat> will be unable to detect it. |
|
|
1521 | |
|
|
1522 | The solution to this is to delay acting on a change for a second (or till |
|
|
1523 | the next second boundary), using a roughly one-second delay C<ev_timer> |
|
|
1524 | (C<ev_timer_set (w, 0., 1.01); ev_timer_again (loop, w)>). The C<.01> |
|
|
1525 | is added to work around small timing inconsistencies of some operating |
|
|
1526 | systems. |
|
|
1527 | |
|
|
1528 | =head3 Watcher-Specific Functions and Data Members |
1212 | |
1529 | |
1213 | =over 4 |
1530 | =over 4 |
1214 | |
1531 | |
1215 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1532 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1216 | |
1533 | |
… | |
… | |
1252 | =item const char *path [read-only] |
1569 | =item const char *path [read-only] |
1253 | |
1570 | |
1254 | The filesystem path that is being watched. |
1571 | The filesystem path that is being watched. |
1255 | |
1572 | |
1256 | =back |
1573 | =back |
|
|
1574 | |
|
|
1575 | =head3 Examples |
1257 | |
1576 | |
1258 | Example: Watch C</etc/passwd> for attribute changes. |
1577 | Example: Watch C</etc/passwd> for attribute changes. |
1259 | |
1578 | |
1260 | static void |
1579 | static void |
1261 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
1580 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
… | |
… | |
1274 | } |
1593 | } |
1275 | |
1594 | |
1276 | ... |
1595 | ... |
1277 | ev_stat passwd; |
1596 | ev_stat passwd; |
1278 | |
1597 | |
1279 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd"); |
1598 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.); |
1280 | ev_stat_start (loop, &passwd); |
1599 | ev_stat_start (loop, &passwd); |
1281 | |
1600 | |
|
|
1601 | Example: Like above, but additionally use a one-second delay so we do not |
|
|
1602 | miss updates (however, frequent updates will delay processing, too, so |
|
|
1603 | one might do the work both on C<ev_stat> callback invocation I<and> on |
|
|
1604 | C<ev_timer> callback invocation). |
|
|
1605 | |
|
|
1606 | static ev_stat passwd; |
|
|
1607 | static ev_timer timer; |
|
|
1608 | |
|
|
1609 | static void |
|
|
1610 | timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1611 | { |
|
|
1612 | ev_timer_stop (EV_A_ w); |
|
|
1613 | |
|
|
1614 | /* now it's one second after the most recent passwd change */ |
|
|
1615 | } |
|
|
1616 | |
|
|
1617 | static void |
|
|
1618 | stat_cb (EV_P_ ev_stat *w, int revents) |
|
|
1619 | { |
|
|
1620 | /* reset the one-second timer */ |
|
|
1621 | ev_timer_again (EV_A_ &timer); |
|
|
1622 | } |
|
|
1623 | |
|
|
1624 | ... |
|
|
1625 | ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); |
|
|
1626 | ev_stat_start (loop, &passwd); |
|
|
1627 | ev_timer_init (&timer, timer_cb, 0., 1.01); |
|
|
1628 | |
1282 | |
1629 | |
1283 | =head2 C<ev_idle> - when you've got nothing better to do... |
1630 | =head2 C<ev_idle> - when you've got nothing better to do... |
1284 | |
1631 | |
1285 | Idle watchers trigger events when there are no other events are pending |
1632 | Idle watchers trigger events when no other events of the same or higher |
1286 | (prepare, check and other idle watchers do not count). That is, as long |
1633 | priority are pending (prepare, check and other idle watchers do not |
1287 | as your process is busy handling sockets or timeouts (or even signals, |
1634 | count). |
1288 | imagine) it will not be triggered. But when your process is idle all idle |
1635 | |
1289 | watchers are being called again and again, once per event loop iteration - |
1636 | That is, as long as your process is busy handling sockets or timeouts |
|
|
1637 | (or even signals, imagine) of the same or higher priority it will not be |
|
|
1638 | triggered. But when your process is idle (or only lower-priority watchers |
|
|
1639 | are pending), the idle watchers are being called once per event loop |
1290 | until stopped, that is, or your process receives more events and becomes |
1640 | iteration - until stopped, that is, or your process receives more events |
1291 | busy. |
1641 | and becomes busy again with higher priority stuff. |
1292 | |
1642 | |
1293 | The most noteworthy effect is that as long as any idle watchers are |
1643 | The most noteworthy effect is that as long as any idle watchers are |
1294 | active, the process will not block when waiting for new events. |
1644 | active, the process will not block when waiting for new events. |
1295 | |
1645 | |
1296 | Apart from keeping your process non-blocking (which is a useful |
1646 | Apart from keeping your process non-blocking (which is a useful |
1297 | effect on its own sometimes), idle watchers are a good place to do |
1647 | effect on its own sometimes), idle watchers are a good place to do |
1298 | "pseudo-background processing", or delay processing stuff to after the |
1648 | "pseudo-background processing", or delay processing stuff to after the |
1299 | event loop has handled all outstanding events. |
1649 | event loop has handled all outstanding events. |
|
|
1650 | |
|
|
1651 | =head3 Watcher-Specific Functions and Data Members |
1300 | |
1652 | |
1301 | =over 4 |
1653 | =over 4 |
1302 | |
1654 | |
1303 | =item ev_idle_init (ev_signal *, callback) |
1655 | =item ev_idle_init (ev_signal *, callback) |
1304 | |
1656 | |
… | |
… | |
1362 | with priority higher than or equal to the event loop and one coroutine |
1714 | with priority higher than or equal to the event loop and one coroutine |
1363 | of lower priority, but only once, using idle watchers to keep the event |
1715 | of lower priority, but only once, using idle watchers to keep the event |
1364 | loop from blocking if lower-priority coroutines are active, thus mapping |
1716 | loop from blocking if lower-priority coroutines are active, thus mapping |
1365 | low-priority coroutines to idle/background tasks). |
1717 | low-priority coroutines to idle/background tasks). |
1366 | |
1718 | |
|
|
1719 | It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>) |
|
|
1720 | priority, to ensure that they are being run before any other watchers |
|
|
1721 | after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers, |
|
|
1722 | too) should not activate ("feed") events into libev. While libev fully |
|
|
1723 | supports this, they will be called before other C<ev_check> watchers |
|
|
1724 | did their job. As C<ev_check> watchers are often used to embed other |
|
|
1725 | (non-libev) event loops those other event loops might be in an unusable |
|
|
1726 | state until their C<ev_check> watcher ran (always remind yourself to |
|
|
1727 | coexist peacefully with others). |
|
|
1728 | |
|
|
1729 | =head3 Watcher-Specific Functions and Data Members |
|
|
1730 | |
1367 | =over 4 |
1731 | =over 4 |
1368 | |
1732 | |
1369 | =item ev_prepare_init (ev_prepare *, callback) |
1733 | =item ev_prepare_init (ev_prepare *, callback) |
1370 | |
1734 | |
1371 | =item ev_check_init (ev_check *, callback) |
1735 | =item ev_check_init (ev_check *, callback) |
… | |
… | |
1374 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1738 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1375 | macros, but using them is utterly, utterly and completely pointless. |
1739 | macros, but using them is utterly, utterly and completely pointless. |
1376 | |
1740 | |
1377 | =back |
1741 | =back |
1378 | |
1742 | |
1379 | Example: To include a library such as adns, you would add IO watchers |
1743 | There are a number of principal ways to embed other event loops or modules |
1380 | and a timeout watcher in a prepare handler, as required by libadns, and |
1744 | into libev. Here are some ideas on how to include libadns into libev |
|
|
1745 | (there is a Perl module named C<EV::ADNS> that does this, which you could |
|
|
1746 | use for an actually working example. Another Perl module named C<EV::Glib> |
|
|
1747 | embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV |
|
|
1748 | into the Glib event loop). |
|
|
1749 | |
|
|
1750 | Method 1: Add IO watchers and a timeout watcher in a prepare handler, |
1381 | in a check watcher, destroy them and call into libadns. What follows is |
1751 | and in a check watcher, destroy them and call into libadns. What follows |
1382 | pseudo-code only of course: |
1752 | is pseudo-code only of course. This requires you to either use a low |
|
|
1753 | priority for the check watcher or use C<ev_clear_pending> explicitly, as |
|
|
1754 | the callbacks for the IO/timeout watchers might not have been called yet. |
1383 | |
1755 | |
1384 | static ev_io iow [nfd]; |
1756 | static ev_io iow [nfd]; |
1385 | static ev_timer tw; |
1757 | static ev_timer tw; |
1386 | |
1758 | |
1387 | static void |
1759 | static void |
1388 | io_cb (ev_loop *loop, ev_io *w, int revents) |
1760 | io_cb (ev_loop *loop, ev_io *w, int revents) |
1389 | { |
1761 | { |
1390 | // set the relevant poll flags |
|
|
1391 | // could also call adns_processreadable etc. here |
|
|
1392 | struct pollfd *fd = (struct pollfd *)w->data; |
|
|
1393 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1394 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1395 | } |
1762 | } |
1396 | |
1763 | |
1397 | // create io watchers for each fd and a timer before blocking |
1764 | // create io watchers for each fd and a timer before blocking |
1398 | static void |
1765 | static void |
1399 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1766 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1400 | { |
1767 | { |
1401 | int timeout = 3600000;truct pollfd fds [nfd]; |
1768 | int timeout = 3600000; |
|
|
1769 | struct pollfd fds [nfd]; |
1402 | // actual code will need to loop here and realloc etc. |
1770 | // actual code will need to loop here and realloc etc. |
1403 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1771 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1404 | |
1772 | |
1405 | /* the callback is illegal, but won't be called as we stop during check */ |
1773 | /* the callback is illegal, but won't be called as we stop during check */ |
1406 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1774 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1407 | ev_timer_start (loop, &tw); |
1775 | ev_timer_start (loop, &tw); |
1408 | |
1776 | |
1409 | // create on ev_io per pollfd |
1777 | // create one ev_io per pollfd |
1410 | for (int i = 0; i < nfd; ++i) |
1778 | for (int i = 0; i < nfd; ++i) |
1411 | { |
1779 | { |
1412 | ev_io_init (iow + i, io_cb, fds [i].fd, |
1780 | ev_io_init (iow + i, io_cb, fds [i].fd, |
1413 | ((fds [i].events & POLLIN ? EV_READ : 0) |
1781 | ((fds [i].events & POLLIN ? EV_READ : 0) |
1414 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1782 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1415 | |
1783 | |
1416 | fds [i].revents = 0; |
1784 | fds [i].revents = 0; |
1417 | iow [i].data = fds + i; |
|
|
1418 | ev_io_start (loop, iow + i); |
1785 | ev_io_start (loop, iow + i); |
1419 | } |
1786 | } |
1420 | } |
1787 | } |
1421 | |
1788 | |
1422 | // stop all watchers after blocking |
1789 | // stop all watchers after blocking |
… | |
… | |
1424 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
1791 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
1425 | { |
1792 | { |
1426 | ev_timer_stop (loop, &tw); |
1793 | ev_timer_stop (loop, &tw); |
1427 | |
1794 | |
1428 | for (int i = 0; i < nfd; ++i) |
1795 | for (int i = 0; i < nfd; ++i) |
|
|
1796 | { |
|
|
1797 | // set the relevant poll flags |
|
|
1798 | // could also call adns_processreadable etc. here |
|
|
1799 | struct pollfd *fd = fds + i; |
|
|
1800 | int revents = ev_clear_pending (iow + i); |
|
|
1801 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1802 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1803 | |
|
|
1804 | // now stop the watcher |
1429 | ev_io_stop (loop, iow + i); |
1805 | ev_io_stop (loop, iow + i); |
|
|
1806 | } |
1430 | |
1807 | |
1431 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
1808 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
1809 | } |
|
|
1810 | |
|
|
1811 | Method 2: This would be just like method 1, but you run C<adns_afterpoll> |
|
|
1812 | in the prepare watcher and would dispose of the check watcher. |
|
|
1813 | |
|
|
1814 | Method 3: If the module to be embedded supports explicit event |
|
|
1815 | notification (adns does), you can also make use of the actual watcher |
|
|
1816 | callbacks, and only destroy/create the watchers in the prepare watcher. |
|
|
1817 | |
|
|
1818 | static void |
|
|
1819 | timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1820 | { |
|
|
1821 | adns_state ads = (adns_state)w->data; |
|
|
1822 | update_now (EV_A); |
|
|
1823 | |
|
|
1824 | adns_processtimeouts (ads, &tv_now); |
|
|
1825 | } |
|
|
1826 | |
|
|
1827 | static void |
|
|
1828 | io_cb (EV_P_ ev_io *w, int revents) |
|
|
1829 | { |
|
|
1830 | adns_state ads = (adns_state)w->data; |
|
|
1831 | update_now (EV_A); |
|
|
1832 | |
|
|
1833 | if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now); |
|
|
1834 | if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now); |
|
|
1835 | } |
|
|
1836 | |
|
|
1837 | // do not ever call adns_afterpoll |
|
|
1838 | |
|
|
1839 | Method 4: Do not use a prepare or check watcher because the module you |
|
|
1840 | want to embed is too inflexible to support it. Instead, youc na override |
|
|
1841 | their poll function. The drawback with this solution is that the main |
|
|
1842 | loop is now no longer controllable by EV. The C<Glib::EV> module does |
|
|
1843 | this. |
|
|
1844 | |
|
|
1845 | static gint |
|
|
1846 | event_poll_func (GPollFD *fds, guint nfds, gint timeout) |
|
|
1847 | { |
|
|
1848 | int got_events = 0; |
|
|
1849 | |
|
|
1850 | for (n = 0; n < nfds; ++n) |
|
|
1851 | // create/start io watcher that sets the relevant bits in fds[n] and increment got_events |
|
|
1852 | |
|
|
1853 | if (timeout >= 0) |
|
|
1854 | // create/start timer |
|
|
1855 | |
|
|
1856 | // poll |
|
|
1857 | ev_loop (EV_A_ 0); |
|
|
1858 | |
|
|
1859 | // stop timer again |
|
|
1860 | if (timeout >= 0) |
|
|
1861 | ev_timer_stop (EV_A_ &to); |
|
|
1862 | |
|
|
1863 | // stop io watchers again - their callbacks should have set |
|
|
1864 | for (n = 0; n < nfds; ++n) |
|
|
1865 | ev_io_stop (EV_A_ iow [n]); |
|
|
1866 | |
|
|
1867 | return got_events; |
1432 | } |
1868 | } |
1433 | |
1869 | |
1434 | |
1870 | |
1435 | =head2 C<ev_embed> - when one backend isn't enough... |
1871 | =head2 C<ev_embed> - when one backend isn't enough... |
1436 | |
1872 | |
… | |
… | |
1500 | ev_embed_start (loop_hi, &embed); |
1936 | ev_embed_start (loop_hi, &embed); |
1501 | } |
1937 | } |
1502 | else |
1938 | else |
1503 | loop_lo = loop_hi; |
1939 | loop_lo = loop_hi; |
1504 | |
1940 | |
|
|
1941 | =head3 Watcher-Specific Functions and Data Members |
|
|
1942 | |
1505 | =over 4 |
1943 | =over 4 |
1506 | |
1944 | |
1507 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
1945 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
1508 | |
1946 | |
1509 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
1947 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
… | |
… | |
1518 | |
1956 | |
1519 | Make a single, non-blocking sweep over the embedded loop. This works |
1957 | Make a single, non-blocking sweep over the embedded loop. This works |
1520 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
1958 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
1521 | apropriate way for embedded loops. |
1959 | apropriate way for embedded loops. |
1522 | |
1960 | |
1523 | =item struct ev_loop *loop [read-only] |
1961 | =item struct ev_loop *other [read-only] |
1524 | |
1962 | |
1525 | The embedded event loop. |
1963 | The embedded event loop. |
1526 | |
1964 | |
1527 | =back |
1965 | =back |
1528 | |
1966 | |
… | |
… | |
1535 | event loop blocks next and before C<ev_check> watchers are being called, |
1973 | event loop blocks next and before C<ev_check> watchers are being called, |
1536 | and only in the child after the fork. If whoever good citizen calling |
1974 | and only in the child after the fork. If whoever good citizen calling |
1537 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
1975 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
1538 | handlers will be invoked, too, of course. |
1976 | handlers will be invoked, too, of course. |
1539 | |
1977 | |
|
|
1978 | =head3 Watcher-Specific Functions and Data Members |
|
|
1979 | |
1540 | =over 4 |
1980 | =over 4 |
1541 | |
1981 | |
1542 | =item ev_fork_init (ev_signal *, callback) |
1982 | =item ev_fork_init (ev_signal *, callback) |
1543 | |
1983 | |
1544 | Initialises and configures the fork watcher - it has no parameters of any |
1984 | Initialises and configures the fork watcher - it has no parameters of any |
… | |
… | |
1640 | |
2080 | |
1641 | To use it, |
2081 | To use it, |
1642 | |
2082 | |
1643 | #include <ev++.h> |
2083 | #include <ev++.h> |
1644 | |
2084 | |
1645 | (it is not installed by default). This automatically includes F<ev.h> |
2085 | This automatically includes F<ev.h> and puts all of its definitions (many |
1646 | and puts all of its definitions (many of them macros) into the global |
2086 | of them macros) into the global namespace. All C++ specific things are |
1647 | namespace. All C++ specific things are put into the C<ev> namespace. |
2087 | put into the C<ev> namespace. It should support all the same embedding |
|
|
2088 | options as F<ev.h>, most notably C<EV_MULTIPLICITY>. |
1648 | |
2089 | |
1649 | It should support all the same embedding options as F<ev.h>, most notably |
2090 | Care has been taken to keep the overhead low. The only data member the C++ |
1650 | C<EV_MULTIPLICITY>. |
2091 | classes add (compared to plain C-style watchers) is the event loop pointer |
|
|
2092 | that the watcher is associated with (or no additional members at all if |
|
|
2093 | you disable C<EV_MULTIPLICITY> when embedding libev). |
|
|
2094 | |
|
|
2095 | Currently, functions, and static and non-static member functions can be |
|
|
2096 | used as callbacks. Other types should be easy to add as long as they only |
|
|
2097 | need one additional pointer for context. If you need support for other |
|
|
2098 | types of functors please contact the author (preferably after implementing |
|
|
2099 | it). |
1651 | |
2100 | |
1652 | Here is a list of things available in the C<ev> namespace: |
2101 | Here is a list of things available in the C<ev> namespace: |
1653 | |
2102 | |
1654 | =over 4 |
2103 | =over 4 |
1655 | |
2104 | |
… | |
… | |
1671 | |
2120 | |
1672 | All of those classes have these methods: |
2121 | All of those classes have these methods: |
1673 | |
2122 | |
1674 | =over 4 |
2123 | =over 4 |
1675 | |
2124 | |
1676 | =item ev::TYPE::TYPE (object *, object::method *) |
2125 | =item ev::TYPE::TYPE () |
1677 | |
2126 | |
1678 | =item ev::TYPE::TYPE (object *, object::method *, struct ev_loop *) |
2127 | =item ev::TYPE::TYPE (struct ev_loop *) |
1679 | |
2128 | |
1680 | =item ev::TYPE::~TYPE |
2129 | =item ev::TYPE::~TYPE |
1681 | |
2130 | |
1682 | The constructor takes a pointer to an object and a method pointer to |
2131 | The constructor (optionally) takes an event loop to associate the watcher |
1683 | the event handler callback to call in this class. The constructor calls |
2132 | with. If it is omitted, it will use C<EV_DEFAULT>. |
1684 | C<ev_init> for you, which means you have to call the C<set> method |
2133 | |
1685 | before starting it. If you do not specify a loop then the constructor |
2134 | The constructor calls C<ev_init> for you, which means you have to call the |
1686 | automatically associates the default loop with this watcher. |
2135 | C<set> method before starting it. |
|
|
2136 | |
|
|
2137 | It will not set a callback, however: You have to call the templated C<set> |
|
|
2138 | method to set a callback before you can start the watcher. |
|
|
2139 | |
|
|
2140 | (The reason why you have to use a method is a limitation in C++ which does |
|
|
2141 | not allow explicit template arguments for constructors). |
1687 | |
2142 | |
1688 | The destructor automatically stops the watcher if it is active. |
2143 | The destructor automatically stops the watcher if it is active. |
|
|
2144 | |
|
|
2145 | =item w->set<class, &class::method> (object *) |
|
|
2146 | |
|
|
2147 | This method sets the callback method to call. The method has to have a |
|
|
2148 | signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as |
|
|
2149 | first argument and the C<revents> as second. The object must be given as |
|
|
2150 | parameter and is stored in the C<data> member of the watcher. |
|
|
2151 | |
|
|
2152 | This method synthesizes efficient thunking code to call your method from |
|
|
2153 | the C callback that libev requires. If your compiler can inline your |
|
|
2154 | callback (i.e. it is visible to it at the place of the C<set> call and |
|
|
2155 | your compiler is good :), then the method will be fully inlined into the |
|
|
2156 | thunking function, making it as fast as a direct C callback. |
|
|
2157 | |
|
|
2158 | Example: simple class declaration and watcher initialisation |
|
|
2159 | |
|
|
2160 | struct myclass |
|
|
2161 | { |
|
|
2162 | void io_cb (ev::io &w, int revents) { } |
|
|
2163 | } |
|
|
2164 | |
|
|
2165 | myclass obj; |
|
|
2166 | ev::io iow; |
|
|
2167 | iow.set <myclass, &myclass::io_cb> (&obj); |
|
|
2168 | |
|
|
2169 | =item w->set<function> (void *data = 0) |
|
|
2170 | |
|
|
2171 | Also sets a callback, but uses a static method or plain function as |
|
|
2172 | callback. The optional C<data> argument will be stored in the watcher's |
|
|
2173 | C<data> member and is free for you to use. |
|
|
2174 | |
|
|
2175 | The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>. |
|
|
2176 | |
|
|
2177 | See the method-C<set> above for more details. |
|
|
2178 | |
|
|
2179 | Example: |
|
|
2180 | |
|
|
2181 | static void io_cb (ev::io &w, int revents) { } |
|
|
2182 | iow.set <io_cb> (); |
1689 | |
2183 | |
1690 | =item w->set (struct ev_loop *) |
2184 | =item w->set (struct ev_loop *) |
1691 | |
2185 | |
1692 | Associates a different C<struct ev_loop> with this watcher. You can only |
2186 | Associates a different C<struct ev_loop> with this watcher. You can only |
1693 | do this when the watcher is inactive (and not pending either). |
2187 | do this when the watcher is inactive (and not pending either). |
1694 | |
2188 | |
1695 | =item w->set ([args]) |
2189 | =item w->set ([args]) |
1696 | |
2190 | |
1697 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
2191 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
1698 | called at least once. Unlike the C counterpart, an active watcher gets |
2192 | called at least once. Unlike the C counterpart, an active watcher gets |
1699 | automatically stopped and restarted. |
2193 | automatically stopped and restarted when reconfiguring it with this |
|
|
2194 | method. |
1700 | |
2195 | |
1701 | =item w->start () |
2196 | =item w->start () |
1702 | |
2197 | |
1703 | Starts the watcher. Note that there is no C<loop> argument as the |
2198 | Starts the watcher. Note that there is no C<loop> argument, as the |
1704 | constructor already takes the loop. |
2199 | constructor already stores the event loop. |
1705 | |
2200 | |
1706 | =item w->stop () |
2201 | =item w->stop () |
1707 | |
2202 | |
1708 | Stops the watcher if it is active. Again, no C<loop> argument. |
2203 | Stops the watcher if it is active. Again, no C<loop> argument. |
1709 | |
2204 | |
1710 | =item w->again () C<ev::timer>, C<ev::periodic> only |
2205 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
1711 | |
2206 | |
1712 | For C<ev::timer> and C<ev::periodic>, this invokes the corresponding |
2207 | For C<ev::timer> and C<ev::periodic>, this invokes the corresponding |
1713 | C<ev_TYPE_again> function. |
2208 | C<ev_TYPE_again> function. |
1714 | |
2209 | |
1715 | =item w->sweep () C<ev::embed> only |
2210 | =item w->sweep () (C<ev::embed> only) |
1716 | |
2211 | |
1717 | Invokes C<ev_embed_sweep>. |
2212 | Invokes C<ev_embed_sweep>. |
1718 | |
2213 | |
1719 | =item w->update () C<ev::stat> only |
2214 | =item w->update () (C<ev::stat> only) |
1720 | |
2215 | |
1721 | Invokes C<ev_stat_stat>. |
2216 | Invokes C<ev_stat_stat>. |
1722 | |
2217 | |
1723 | =back |
2218 | =back |
1724 | |
2219 | |
… | |
… | |
1734 | |
2229 | |
1735 | myclass (); |
2230 | myclass (); |
1736 | } |
2231 | } |
1737 | |
2232 | |
1738 | myclass::myclass (int fd) |
2233 | myclass::myclass (int fd) |
1739 | : io (this, &myclass::io_cb), |
|
|
1740 | idle (this, &myclass::idle_cb) |
|
|
1741 | { |
2234 | { |
|
|
2235 | io .set <myclass, &myclass::io_cb > (this); |
|
|
2236 | idle.set <myclass, &myclass::idle_cb> (this); |
|
|
2237 | |
1742 | io.start (fd, ev::READ); |
2238 | io.start (fd, ev::READ); |
1743 | } |
2239 | } |
1744 | |
2240 | |
1745 | |
2241 | |
1746 | =head1 MACRO MAGIC |
2242 | =head1 MACRO MAGIC |
1747 | |
2243 | |
1748 | Libev can be compiled with a variety of options, the most fundemantal is |
2244 | Libev can be compiled with a variety of options, the most fundamantal |
1749 | C<EV_MULTIPLICITY>. This option determines wether (most) functions and |
2245 | of which is C<EV_MULTIPLICITY>. This option determines whether (most) |
1750 | callbacks have an initial C<struct ev_loop *> argument. |
2246 | functions and callbacks have an initial C<struct ev_loop *> argument. |
1751 | |
2247 | |
1752 | To make it easier to write programs that cope with either variant, the |
2248 | To make it easier to write programs that cope with either variant, the |
1753 | following macros are defined: |
2249 | following macros are defined: |
1754 | |
2250 | |
1755 | =over 4 |
2251 | =over 4 |
… | |
… | |
1787 | Similar to the other two macros, this gives you the value of the default |
2283 | Similar to the other two macros, this gives you the value of the default |
1788 | loop, if multiple loops are supported ("ev loop default"). |
2284 | loop, if multiple loops are supported ("ev loop default"). |
1789 | |
2285 | |
1790 | =back |
2286 | =back |
1791 | |
2287 | |
1792 | Example: Declare and initialise a check watcher, working regardless of |
2288 | Example: Declare and initialise a check watcher, utilising the above |
1793 | wether multiple loops are supported or not. |
2289 | macros so it will work regardless of whether multiple loops are supported |
|
|
2290 | or not. |
1794 | |
2291 | |
1795 | static void |
2292 | static void |
1796 | check_cb (EV_P_ ev_timer *w, int revents) |
2293 | check_cb (EV_P_ ev_timer *w, int revents) |
1797 | { |
2294 | { |
1798 | ev_check_stop (EV_A_ w); |
2295 | ev_check_stop (EV_A_ w); |
… | |
… | |
1801 | ev_check check; |
2298 | ev_check check; |
1802 | ev_check_init (&check, check_cb); |
2299 | ev_check_init (&check, check_cb); |
1803 | ev_check_start (EV_DEFAULT_ &check); |
2300 | ev_check_start (EV_DEFAULT_ &check); |
1804 | ev_loop (EV_DEFAULT_ 0); |
2301 | ev_loop (EV_DEFAULT_ 0); |
1805 | |
2302 | |
1806 | |
|
|
1807 | =head1 EMBEDDING |
2303 | =head1 EMBEDDING |
1808 | |
2304 | |
1809 | Libev can (and often is) directly embedded into host |
2305 | Libev can (and often is) directly embedded into host |
1810 | applications. Examples of applications that embed it include the Deliantra |
2306 | applications. Examples of applications that embed it include the Deliantra |
1811 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
2307 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
1812 | and rxvt-unicode. |
2308 | and rxvt-unicode. |
1813 | |
2309 | |
1814 | The goal is to enable you to just copy the neecssary files into your |
2310 | The goal is to enable you to just copy the necessary files into your |
1815 | source directory without having to change even a single line in them, so |
2311 | source directory without having to change even a single line in them, so |
1816 | you can easily upgrade by simply copying (or having a checked-out copy of |
2312 | you can easily upgrade by simply copying (or having a checked-out copy of |
1817 | libev somewhere in your source tree). |
2313 | libev somewhere in your source tree). |
1818 | |
2314 | |
1819 | =head2 FILESETS |
2315 | =head2 FILESETS |
… | |
… | |
1850 | ev_vars.h |
2346 | ev_vars.h |
1851 | ev_wrap.h |
2347 | ev_wrap.h |
1852 | |
2348 | |
1853 | ev_win32.c required on win32 platforms only |
2349 | ev_win32.c required on win32 platforms only |
1854 | |
2350 | |
1855 | ev_select.c only when select backend is enabled (which is by default) |
2351 | ev_select.c only when select backend is enabled (which is enabled by default) |
1856 | ev_poll.c only when poll backend is enabled (disabled by default) |
2352 | ev_poll.c only when poll backend is enabled (disabled by default) |
1857 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
2353 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
1858 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
2354 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
1859 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
2355 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
1860 | |
2356 | |
… | |
… | |
1909 | |
2405 | |
1910 | If defined to be C<1>, libev will try to detect the availability of the |
2406 | If defined to be C<1>, libev will try to detect the availability of the |
1911 | monotonic clock option at both compiletime and runtime. Otherwise no use |
2407 | monotonic clock option at both compiletime and runtime. Otherwise no use |
1912 | of the monotonic clock option will be attempted. If you enable this, you |
2408 | of the monotonic clock option will be attempted. If you enable this, you |
1913 | usually have to link against librt or something similar. Enabling it when |
2409 | usually have to link against librt or something similar. Enabling it when |
1914 | the functionality isn't available is safe, though, althoguh you have |
2410 | the functionality isn't available is safe, though, although you have |
1915 | to make sure you link against any libraries where the C<clock_gettime> |
2411 | to make sure you link against any libraries where the C<clock_gettime> |
1916 | function is hiding in (often F<-lrt>). |
2412 | function is hiding in (often F<-lrt>). |
1917 | |
2413 | |
1918 | =item EV_USE_REALTIME |
2414 | =item EV_USE_REALTIME |
1919 | |
2415 | |
1920 | If defined to be C<1>, libev will try to detect the availability of the |
2416 | If defined to be C<1>, libev will try to detect the availability of the |
1921 | realtime clock option at compiletime (and assume its availability at |
2417 | realtime clock option at compiletime (and assume its availability at |
1922 | runtime if successful). Otherwise no use of the realtime clock option will |
2418 | runtime if successful). Otherwise no use of the realtime clock option will |
1923 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
2419 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
1924 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries |
2420 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See the |
1925 | in the description of C<EV_USE_MONOTONIC>, though. |
2421 | note about libraries in the description of C<EV_USE_MONOTONIC>, though. |
|
|
2422 | |
|
|
2423 | =item EV_USE_NANOSLEEP |
|
|
2424 | |
|
|
2425 | If defined to be C<1>, libev will assume that C<nanosleep ()> is available |
|
|
2426 | and will use it for delays. Otherwise it will use C<select ()>. |
1926 | |
2427 | |
1927 | =item EV_USE_SELECT |
2428 | =item EV_USE_SELECT |
1928 | |
2429 | |
1929 | If undefined or defined to be C<1>, libev will compile in support for the |
2430 | If undefined or defined to be C<1>, libev will compile in support for the |
1930 | C<select>(2) backend. No attempt at autodetection will be done: if no |
2431 | C<select>(2) backend. No attempt at autodetection will be done: if no |
… | |
… | |
1985 | |
2486 | |
1986 | =item EV_USE_DEVPOLL |
2487 | =item EV_USE_DEVPOLL |
1987 | |
2488 | |
1988 | reserved for future expansion, works like the USE symbols above. |
2489 | reserved for future expansion, works like the USE symbols above. |
1989 | |
2490 | |
|
|
2491 | =item EV_USE_INOTIFY |
|
|
2492 | |
|
|
2493 | If defined to be C<1>, libev will compile in support for the Linux inotify |
|
|
2494 | interface to speed up C<ev_stat> watchers. Its actual availability will |
|
|
2495 | be detected at runtime. |
|
|
2496 | |
1990 | =item EV_H |
2497 | =item EV_H |
1991 | |
2498 | |
1992 | The name of the F<ev.h> header file used to include it. The default if |
2499 | The name of the F<ev.h> header file used to include it. The default if |
1993 | undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This |
2500 | undefined is C<"ev.h"> in F<event.h> and F<ev.c>. This can be used to |
1994 | can be used to virtually rename the F<ev.h> header file in case of conflicts. |
2501 | virtually rename the F<ev.h> header file in case of conflicts. |
1995 | |
2502 | |
1996 | =item EV_CONFIG_H |
2503 | =item EV_CONFIG_H |
1997 | |
2504 | |
1998 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
2505 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
1999 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
2506 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
2000 | C<EV_H>, above. |
2507 | C<EV_H>, above. |
2001 | |
2508 | |
2002 | =item EV_EVENT_H |
2509 | =item EV_EVENT_H |
2003 | |
2510 | |
2004 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
2511 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
2005 | of how the F<event.h> header can be found. |
2512 | of how the F<event.h> header can be found, the dfeault is C<"event.h">. |
2006 | |
2513 | |
2007 | =item EV_PROTOTYPES |
2514 | =item EV_PROTOTYPES |
2008 | |
2515 | |
2009 | If defined to be C<0>, then F<ev.h> will not define any function |
2516 | If defined to be C<0>, then F<ev.h> will not define any function |
2010 | prototypes, but still define all the structs and other symbols. This is |
2517 | prototypes, but still define all the structs and other symbols. This is |
… | |
… | |
2017 | will have the C<struct ev_loop *> as first argument, and you can create |
2524 | will have the C<struct ev_loop *> as first argument, and you can create |
2018 | additional independent event loops. Otherwise there will be no support |
2525 | additional independent event loops. Otherwise there will be no support |
2019 | for multiple event loops and there is no first event loop pointer |
2526 | for multiple event loops and there is no first event loop pointer |
2020 | argument. Instead, all functions act on the single default loop. |
2527 | argument. Instead, all functions act on the single default loop. |
2021 | |
2528 | |
|
|
2529 | =item EV_MINPRI |
|
|
2530 | |
|
|
2531 | =item EV_MAXPRI |
|
|
2532 | |
|
|
2533 | The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to |
|
|
2534 | C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can |
|
|
2535 | provide for more priorities by overriding those symbols (usually defined |
|
|
2536 | to be C<-2> and C<2>, respectively). |
|
|
2537 | |
|
|
2538 | When doing priority-based operations, libev usually has to linearly search |
|
|
2539 | all the priorities, so having many of them (hundreds) uses a lot of space |
|
|
2540 | and time, so using the defaults of five priorities (-2 .. +2) is usually |
|
|
2541 | fine. |
|
|
2542 | |
|
|
2543 | If your embedding app does not need any priorities, defining these both to |
|
|
2544 | C<0> will save some memory and cpu. |
|
|
2545 | |
2022 | =item EV_PERIODIC_ENABLE |
2546 | =item EV_PERIODIC_ENABLE |
2023 | |
2547 | |
2024 | If undefined or defined to be C<1>, then periodic timers are supported. If |
2548 | If undefined or defined to be C<1>, then periodic timers are supported. If |
2025 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
2549 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
2026 | code. |
2550 | code. |
2027 | |
2551 | |
|
|
2552 | =item EV_IDLE_ENABLE |
|
|
2553 | |
|
|
2554 | If undefined or defined to be C<1>, then idle watchers are supported. If |
|
|
2555 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
2556 | code. |
|
|
2557 | |
2028 | =item EV_EMBED_ENABLE |
2558 | =item EV_EMBED_ENABLE |
2029 | |
2559 | |
2030 | If undefined or defined to be C<1>, then embed watchers are supported. If |
2560 | If undefined or defined to be C<1>, then embed watchers are supported. If |
2031 | defined to be C<0>, then they are not. |
2561 | defined to be C<0>, then they are not. |
2032 | |
2562 | |
… | |
… | |
2049 | =item EV_PID_HASHSIZE |
2579 | =item EV_PID_HASHSIZE |
2050 | |
2580 | |
2051 | C<ev_child> watchers use a small hash table to distribute workload by |
2581 | C<ev_child> watchers use a small hash table to distribute workload by |
2052 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
2582 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
2053 | than enough. If you need to manage thousands of children you might want to |
2583 | than enough. If you need to manage thousands of children you might want to |
2054 | increase this value. |
2584 | increase this value (I<must> be a power of two). |
|
|
2585 | |
|
|
2586 | =item EV_INOTIFY_HASHSIZE |
|
|
2587 | |
|
|
2588 | C<ev_stat> watchers use a small hash table to distribute workload by |
|
|
2589 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
|
|
2590 | usually more than enough. If you need to manage thousands of C<ev_stat> |
|
|
2591 | watchers you might want to increase this value (I<must> be a power of |
|
|
2592 | two). |
2055 | |
2593 | |
2056 | =item EV_COMMON |
2594 | =item EV_COMMON |
2057 | |
2595 | |
2058 | By default, all watchers have a C<void *data> member. By redefining |
2596 | By default, all watchers have a C<void *data> member. By redefining |
2059 | this macro to a something else you can include more and other types of |
2597 | this macro to a something else you can include more and other types of |
… | |
… | |
2072 | |
2610 | |
2073 | =item ev_set_cb (ev, cb) |
2611 | =item ev_set_cb (ev, cb) |
2074 | |
2612 | |
2075 | Can be used to change the callback member declaration in each watcher, |
2613 | Can be used to change the callback member declaration in each watcher, |
2076 | and the way callbacks are invoked and set. Must expand to a struct member |
2614 | and the way callbacks are invoked and set. Must expand to a struct member |
2077 | definition and a statement, respectively. See the F<ev.v> header file for |
2615 | definition and a statement, respectively. See the F<ev.h> header file for |
2078 | their default definitions. One possible use for overriding these is to |
2616 | their default definitions. One possible use for overriding these is to |
2079 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
2617 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
2080 | method calls instead of plain function calls in C++. |
2618 | method calls instead of plain function calls in C++. |
|
|
2619 | |
|
|
2620 | =head2 EXPORTED API SYMBOLS |
|
|
2621 | |
|
|
2622 | If you need to re-export the API (e.g. via a dll) and you need a list of |
|
|
2623 | exported symbols, you can use the provided F<Symbol.*> files which list |
|
|
2624 | all public symbols, one per line: |
|
|
2625 | |
|
|
2626 | Symbols.ev for libev proper |
|
|
2627 | Symbols.event for the libevent emulation |
|
|
2628 | |
|
|
2629 | This can also be used to rename all public symbols to avoid clashes with |
|
|
2630 | multiple versions of libev linked together (which is obviously bad in |
|
|
2631 | itself, but sometimes it is inconvinient to avoid this). |
|
|
2632 | |
|
|
2633 | A sed command like this will create wrapper C<#define>'s that you need to |
|
|
2634 | include before including F<ev.h>: |
|
|
2635 | |
|
|
2636 | <Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h |
|
|
2637 | |
|
|
2638 | This would create a file F<wrap.h> which essentially looks like this: |
|
|
2639 | |
|
|
2640 | #define ev_backend myprefix_ev_backend |
|
|
2641 | #define ev_check_start myprefix_ev_check_start |
|
|
2642 | #define ev_check_stop myprefix_ev_check_stop |
|
|
2643 | ... |
2081 | |
2644 | |
2082 | =head2 EXAMPLES |
2645 | =head2 EXAMPLES |
2083 | |
2646 | |
2084 | For a real-world example of a program the includes libev |
2647 | For a real-world example of a program the includes libev |
2085 | verbatim, you can have a look at the EV perl module |
2648 | verbatim, you can have a look at the EV perl module |
… | |
… | |
2088 | interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file |
2651 | interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file |
2089 | will be compiled. It is pretty complex because it provides its own header |
2652 | will be compiled. It is pretty complex because it provides its own header |
2090 | file. |
2653 | file. |
2091 | |
2654 | |
2092 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
2655 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
2093 | that everybody includes and which overrides some autoconf choices: |
2656 | that everybody includes and which overrides some configure choices: |
2094 | |
2657 | |
|
|
2658 | #define EV_MINIMAL 1 |
2095 | #define EV_USE_POLL 0 |
2659 | #define EV_USE_POLL 0 |
2096 | #define EV_MULTIPLICITY 0 |
2660 | #define EV_MULTIPLICITY 0 |
2097 | #define EV_PERIODICS 0 |
2661 | #define EV_PERIODIC_ENABLE 0 |
|
|
2662 | #define EV_STAT_ENABLE 0 |
|
|
2663 | #define EV_FORK_ENABLE 0 |
2098 | #define EV_CONFIG_H <config.h> |
2664 | #define EV_CONFIG_H <config.h> |
|
|
2665 | #define EV_MINPRI 0 |
|
|
2666 | #define EV_MAXPRI 0 |
2099 | |
2667 | |
2100 | #include "ev++.h" |
2668 | #include "ev++.h" |
2101 | |
2669 | |
2102 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
2670 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
2103 | |
2671 | |
… | |
… | |
2109 | |
2677 | |
2110 | In this section the complexities of (many of) the algorithms used inside |
2678 | In this section the complexities of (many of) the algorithms used inside |
2111 | libev will be explained. For complexity discussions about backends see the |
2679 | libev will be explained. For complexity discussions about backends see the |
2112 | documentation for C<ev_default_init>. |
2680 | documentation for C<ev_default_init>. |
2113 | |
2681 | |
|
|
2682 | All of the following are about amortised time: If an array needs to be |
|
|
2683 | extended, libev needs to realloc and move the whole array, but this |
|
|
2684 | happens asymptotically never with higher number of elements, so O(1) might |
|
|
2685 | mean it might do a lengthy realloc operation in rare cases, but on average |
|
|
2686 | it is much faster and asymptotically approaches constant time. |
|
|
2687 | |
2114 | =over 4 |
2688 | =over 4 |
2115 | |
2689 | |
2116 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2690 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2117 | |
2691 | |
|
|
2692 | This means that, when you have a watcher that triggers in one hour and |
|
|
2693 | there are 100 watchers that would trigger before that then inserting will |
|
|
2694 | have to skip roughly seven (C<ld 100>) of these watchers. |
|
|
2695 | |
2118 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
2696 | =item Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers) |
|
|
2697 | |
|
|
2698 | That means that changing a timer costs less than removing/adding them |
|
|
2699 | as only the relative motion in the event queue has to be paid for. |
2119 | |
2700 | |
2120 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2701 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2121 | |
2702 | |
|
|
2703 | These just add the watcher into an array or at the head of a list. |
|
|
2704 | |
2122 | =item Stopping check/prepare/idle watchers: O(1) |
2705 | =item Stopping check/prepare/idle watchers: O(1) |
2123 | |
2706 | |
2124 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16)) |
2707 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2125 | |
2708 | |
|
|
2709 | These watchers are stored in lists then need to be walked to find the |
|
|
2710 | correct watcher to remove. The lists are usually short (you don't usually |
|
|
2711 | have many watchers waiting for the same fd or signal). |
|
|
2712 | |
2126 | =item Finding the next timer per loop iteration: O(1) |
2713 | =item Finding the next timer in each loop iteration: O(1) |
|
|
2714 | |
|
|
2715 | By virtue of using a binary heap, the next timer is always found at the |
|
|
2716 | beginning of the storage array. |
2127 | |
2717 | |
2128 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2718 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2129 | |
2719 | |
2130 | =item Activating one watcher: O(1) |
2720 | A change means an I/O watcher gets started or stopped, which requires |
|
|
2721 | libev to recalculate its status (and possibly tell the kernel, depending |
|
|
2722 | on backend and wether C<ev_io_set> was used). |
|
|
2723 | |
|
|
2724 | =item Activating one watcher (putting it into the pending state): O(1) |
|
|
2725 | |
|
|
2726 | =item Priority handling: O(number_of_priorities) |
|
|
2727 | |
|
|
2728 | Priorities are implemented by allocating some space for each |
|
|
2729 | priority. When doing priority-based operations, libev usually has to |
|
|
2730 | linearly search all the priorities, but starting/stopping and activating |
|
|
2731 | watchers becomes O(1) w.r.t. prioritiy handling. |
2131 | |
2732 | |
2132 | =back |
2733 | =back |
2133 | |
2734 | |
2134 | |
2735 | |
2135 | =head1 AUTHOR |
2736 | =head1 AUTHOR |