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2 | |
2 | |
3 | libev - a high performance full-featured event loop written in C |
3 | libev - a high performance full-featured event loop written in C |
4 | |
4 | |
5 | =head1 SYNOPSIS |
5 | =head1 SYNOPSIS |
6 | |
6 | |
7 | /* this is the only header you need */ |
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8 | #include <ev.h> |
7 | #include <ev.h> |
9 | |
8 | |
10 | /* what follows is a fully working example program */ |
9 | =head2 EXAMPLE PROGRAM |
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10 | |
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11 | #include <ev.h> |
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12 | |
11 | ev_io stdin_watcher; |
13 | ev_io stdin_watcher; |
12 | ev_timer timeout_watcher; |
14 | ev_timer timeout_watcher; |
13 | |
15 | |
14 | /* called when data readable on stdin */ |
16 | /* called when data readable on stdin */ |
15 | static void |
17 | static void |
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46 | return 0; |
48 | return 0; |
47 | } |
49 | } |
48 | |
50 | |
49 | =head1 DESCRIPTION |
51 | =head1 DESCRIPTION |
50 | |
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 | |
51 | 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 |
52 | 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 |
53 | these event sources and provide your program with events. |
59 | these event sources and provide your program with events. |
54 | |
60 | |
55 | 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 |
56 | (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 |
57 | communicate events via a callback mechanism. |
63 | communicate events via a callback mechanism. |
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59 | 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 |
60 | watchers>, which are relatively small C structures you initialise with the |
66 | watchers>, which are relatively small C structures you initialise with the |
61 | 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 |
62 | watcher. |
68 | watcher. |
63 | |
69 | |
64 | =head1 FEATURES |
70 | =head2 FEATURES |
65 | |
71 | |
66 | Libev supports select, poll, the linux-specific epoll and the bsd-specific |
72 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
67 | kqueue mechanisms for file descriptor events, relative timers, absolute |
73 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
68 | timers with customised rescheduling, signal events, process status change |
74 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
69 | events (related to SIGCHLD), and event watchers dealing with the event |
75 | (for C<ev_stat>), relative timers (C<ev_timer>), absolute timers |
70 | loop mechanism itself (idle, prepare and check watchers). It also is quite |
76 | with customised rescheduling (C<ev_periodic>), synchronous signals |
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77 | (C<ev_signal>), process status change events (C<ev_child>), and event |
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78 | watchers dealing with the event loop mechanism itself (C<ev_idle>, |
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79 | C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as |
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80 | file watchers (C<ev_stat>) and even limited support for fork events |
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81 | (C<ev_fork>). |
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82 | |
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83 | It also is quite fast (see this |
71 | fast (see this L<benchmark|http://libev.schmorp.de/bench.html> comparing |
84 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
72 | it to libevent for example). |
85 | for example). |
73 | |
86 | |
74 | =head1 CONVENTIONS |
87 | =head2 CONVENTIONS |
75 | |
88 | |
76 | Libev is very configurable. In this manual the default configuration |
89 | Libev is very configurable. In this manual the default configuration will |
77 | will be described, which supports multiple event loops. For more info |
90 | be described, which supports multiple event loops. For more info about |
78 | about various configuration options please have a look at the file |
91 | various configuration options please have a look at B<EMBED> section in |
79 | F<README.embed> in the libev distribution. If libev was configured without |
92 | this manual. If libev was configured without support for multiple event |
80 | support for multiple event loops, then all functions taking an initial |
93 | loops, then all functions taking an initial argument of name C<loop> |
81 | argument of name C<loop> (which is always of type C<struct ev_loop *>) |
94 | (which is always of type C<struct ev_loop *>) will not have this argument. |
82 | will not have this argument. |
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83 | |
95 | |
84 | =head1 TIME REPRESENTATION |
96 | =head2 TIME REPRESENTATION |
85 | |
97 | |
86 | Libev represents time as a single floating point number, representing the |
98 | Libev represents time as a single floating point number, representing the |
87 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
99 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
88 | 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 |
89 | 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 |
90 | 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 |
91 | 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. |
92 | |
106 | |
93 | =head1 GLOBAL FUNCTIONS |
107 | =head1 GLOBAL FUNCTIONS |
94 | |
108 | |
95 | These functions can be called anytime, even before initialising the |
109 | These functions can be called anytime, even before initialising the |
96 | library in any way. |
110 | library in any way. |
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101 | |
115 | |
102 | 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 |
103 | 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 |
104 | you actually want to know. |
118 | you actually want to know. |
105 | |
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 | |
106 | =item int ev_version_major () |
126 | =item int ev_version_major () |
107 | |
127 | |
108 | =item int ev_version_minor () |
128 | =item int ev_version_minor () |
109 | |
129 | |
110 | 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 |
111 | 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 |
112 | 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 |
113 | 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 |
114 | version of the library your program was compiled against. |
134 | version of the library your program was compiled against. |
115 | |
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 | |
116 | 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, |
117 | as this indicates an incompatible change. Minor versions are usually |
140 | as this indicates an incompatible change. Minor versions are usually |
118 | 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 |
119 | not a problem. |
142 | not a problem. |
120 | |
143 | |
121 | 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 |
122 | version: |
145 | version. |
123 | |
146 | |
124 | assert (("libev version mismatch", |
147 | assert (("libev version mismatch", |
125 | ev_version_major () == EV_VERSION_MAJOR |
148 | ev_version_major () == EV_VERSION_MAJOR |
126 | && ev_version_minor () >= EV_VERSION_MINOR)); |
149 | && ev_version_minor () >= EV_VERSION_MINOR)); |
127 | |
150 | |
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155 | C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for |
178 | C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for |
156 | recommended ones. |
179 | recommended ones. |
157 | |
180 | |
158 | See the description of C<ev_embed> watchers for more info. |
181 | See the description of C<ev_embed> watchers for more info. |
159 | |
182 | |
160 | =item ev_set_allocator (void *(*cb)(void *ptr, size_t size)) |
183 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
161 | |
184 | |
162 | Sets the allocation function to use (the prototype and semantics are |
185 | Sets the allocation function to use (the prototype is similar - the |
163 | 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 |
164 | 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 |
165 | allocated, the library might abort or take some potentially destructive |
188 | memory needs to be allocated, the library might abort or take some |
166 | action. The default is your system realloc function. |
189 | potentially destructive action. The default is your system realloc |
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190 | function. |
167 | |
191 | |
168 | You could override this function in high-availability programs to, say, |
192 | You could override this function in high-availability programs to, say, |
169 | 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, |
170 | 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. |
171 | |
195 | |
172 | Example: replace the libev allocator with one that waits a bit and then |
196 | Example: Replace the libev allocator with one that waits a bit and then |
173 | retries: better than mine). |
197 | retries). |
174 | |
198 | |
175 | static void * |
199 | static void * |
176 | persistent_realloc (void *ptr, size_t size) |
200 | persistent_realloc (void *ptr, size_t size) |
177 | { |
201 | { |
178 | for (;;) |
202 | for (;;) |
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197 | callback is set, then libev will expect it to remedy the sitution, no |
221 | callback is set, then libev will expect it to remedy the sitution, no |
198 | matter what, when it returns. That is, libev will generally retry the |
222 | matter what, when it returns. That is, libev will generally retry the |
199 | requested operation, or, if the condition doesn't go away, do bad stuff |
223 | requested operation, or, if the condition doesn't go away, do bad stuff |
200 | (such as abort). |
224 | (such as abort). |
201 | |
225 | |
202 | Example: do the same thing as libev does internally: |
226 | Example: This is basically the same thing that libev does internally, too. |
203 | |
227 | |
204 | static void |
228 | static void |
205 | fatal_error (const char *msg) |
229 | fatal_error (const char *msg) |
206 | { |
230 | { |
207 | perror (msg); |
231 | perror (msg); |
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257 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
281 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
258 | 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 |
259 | 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 |
260 | around bugs. |
284 | around bugs. |
261 | |
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 | |
262 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
306 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
263 | |
307 | |
264 | 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 |
265 | 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, |
266 | 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 |
267 | 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 |
268 | 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. |
269 | |
320 | |
270 | =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) |
271 | |
322 | |
272 | 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 |
273 | 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 |
274 | 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 |
275 | 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. |
276 | |
329 | |
277 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
330 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
278 | |
331 | |
279 | 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, |
280 | but it scales phenomenally better. While poll and select usually scale like |
333 | but it scales phenomenally better. While poll and select usually scale |
281 | 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), |
282 | 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. |
283 | |
339 | |
284 | 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 |
285 | 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 |
286 | (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 |
287 | 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 |
288 | well if you register events for both fds. |
344 | very well if you register events for both fds. |
289 | |
345 | |
290 | Please note that epoll sometimes generates spurious notifications, so you |
346 | Please note that epoll sometimes generates spurious notifications, so you |
291 | 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 |
292 | (or space) is available. |
348 | (or space) is available. |
293 | |
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 | |
294 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
357 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
295 | |
358 | |
296 | 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 |
297 | 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 |
298 | 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 |
299 | completely useless). For this reason its not being "autodetected" |
362 | it's completely useless). For this reason it's not being "autodetected" |
300 | 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 |
301 | 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. |
302 | |
370 | |
303 | 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 |
304 | 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 |
305 | 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 |
306 | 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 |
307 | 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. |
308 | |
386 | |
309 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
387 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
310 | |
388 | |
311 | 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. |
312 | |
393 | |
313 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
394 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
314 | |
395 | |
315 | 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, |
316 | 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)). |
317 | |
398 | |
318 | 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 |
319 | 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 |
320 | 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. |
321 | |
407 | |
322 | =item C<EVBACKEND_ALL> |
408 | =item C<EVBACKEND_ALL> |
323 | |
409 | |
324 | 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 |
325 | 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 |
326 | 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. |
327 | |
415 | |
328 | =back |
416 | =back |
329 | |
417 | |
330 | 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 |
331 | 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 |
… | |
… | |
353 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
441 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
354 | always distinct from the default loop. Unlike the default loop, it cannot |
442 | always distinct from the default loop. Unlike the default loop, it cannot |
355 | handle signal and child watchers, and attempts to do so will be greeted by |
443 | handle signal and child watchers, and attempts to do so will be greeted by |
356 | undefined behaviour (or a failed assertion if assertions are enabled). |
444 | undefined behaviour (or a failed assertion if assertions are enabled). |
357 | |
445 | |
358 | Example: try to create a event loop that uses epoll and nothing else. |
446 | Example: Try to create a event loop that uses epoll and nothing else. |
359 | |
447 | |
360 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
448 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
361 | if (!epoller) |
449 | if (!epoller) |
362 | fatal ("no epoll found here, maybe it hides under your chair"); |
450 | fatal ("no epoll found here, maybe it hides under your chair"); |
363 | |
451 | |
… | |
… | |
366 | Destroys the default loop again (frees all memory and kernel state |
454 | Destroys the default loop again (frees all memory and kernel state |
367 | 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 |
368 | 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 |
369 | responsibility to either stop all watchers cleanly yoursef I<before> |
457 | responsibility to either stop all watchers cleanly yoursef I<before> |
370 | 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 |
371 | 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 |
372 | for example). |
460 | for example). |
|
|
461 | |
|
|
462 | Note that certain global state, such as signal state, will not be freed by |
|
|
463 | this function, and related watchers (such as signal and child watchers) |
|
|
464 | would need to be stopped manually. |
|
|
465 | |
|
|
466 | In general it is not advisable to call this function except in the |
|
|
467 | rare occasion where you really need to free e.g. the signal handling |
|
|
468 | pipe fds. If you need dynamically allocated loops it is better to use |
|
|
469 | C<ev_loop_new> and C<ev_loop_destroy>). |
373 | |
470 | |
374 | =item ev_loop_destroy (loop) |
471 | =item ev_loop_destroy (loop) |
375 | |
472 | |
376 | 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 |
377 | earlier call to C<ev_loop_new>. |
474 | earlier call to C<ev_loop_new>. |
… | |
… | |
401 | |
498 | |
402 | 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 |
403 | 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 |
404 | 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. |
405 | |
502 | |
|
|
503 | =item unsigned int ev_loop_count (loop) |
|
|
504 | |
|
|
505 | Returns the count of loop iterations for the loop, which is identical to |
|
|
506 | the number of times libev did poll for new events. It starts at C<0> and |
|
|
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 | |
406 | =item unsigned int ev_backend (loop) |
513 | =item unsigned int ev_backend (loop) |
407 | |
514 | |
408 | 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 |
409 | use. |
516 | use. |
410 | |
517 | |
… | |
… | |
412 | |
519 | |
413 | 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 |
414 | received events and started processing them. This timestamp does not |
521 | received events and started processing them. This timestamp does not |
415 | 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 |
416 | 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 |
417 | event occuring (or more correctly, libev finding out about it). |
524 | event occurring (or more correctly, libev finding out about it). |
418 | |
525 | |
419 | =item ev_loop (loop, int flags) |
526 | =item ev_loop (loop, int flags) |
420 | |
527 | |
421 | 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 |
422 | 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 |
… | |
… | |
443 | 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 |
444 | usually a better approach for this kind of thing. |
551 | usually a better approach for this kind of thing. |
445 | |
552 | |
446 | Here are the gory details of what C<ev_loop> does: |
553 | Here are the gory details of what C<ev_loop> does: |
447 | |
554 | |
448 | * If there are no active watchers (reference count is zero), return. |
555 | - Before the first iteration, call any pending watchers. |
449 | - Queue prepare watchers and then call all outstanding watchers. |
556 | * If EVFLAG_FORKCHECK was used, check for a fork. |
|
|
557 | - If a fork was detected, queue and call all fork watchers. |
|
|
558 | - Queue and call all prepare watchers. |
450 | - If we have been forked, recreate the kernel state. |
559 | - If we have been forked, recreate the kernel state. |
451 | - Update the kernel state with all outstanding changes. |
560 | - Update the kernel state with all outstanding changes. |
452 | - Update the "event loop time". |
561 | - Update the "event loop time". |
453 | - Calculate for how long to block. |
562 | - Calculate for how long to sleep or block, if at all |
|
|
563 | (active idle watchers, EVLOOP_NONBLOCK or not having |
|
|
564 | any active watchers at all will result in not sleeping). |
|
|
565 | - Sleep if the I/O and timer collect interval say so. |
454 | - Block the process, waiting for any events. |
566 | - Block the process, waiting for any events. |
455 | - Queue all outstanding I/O (fd) events. |
567 | - Queue all outstanding I/O (fd) events. |
456 | - Update the "event loop time" and do time jump handling. |
568 | - Update the "event loop time" and do time jump handling. |
457 | - Queue all outstanding timers. |
569 | - Queue all outstanding timers. |
458 | - Queue all outstanding periodics. |
570 | - Queue all outstanding periodics. |
459 | - If no events are pending now, queue all idle watchers. |
571 | - If no events are pending now, queue all idle watchers. |
460 | - Queue all check watchers. |
572 | - Queue all check watchers. |
461 | - Call all queued watchers in reverse order (i.e. check watchers first). |
573 | - Call all queued watchers in reverse order (i.e. check watchers first). |
462 | Signals and child watchers are implemented as I/O watchers, and will |
574 | Signals and child watchers are implemented as I/O watchers, and will |
463 | be handled here by queueing them when their watcher gets executed. |
575 | be handled here by queueing them when their watcher gets executed. |
464 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
576 | - If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
465 | were used, return, otherwise continue with step *. |
577 | were used, or there are no active watchers, return, otherwise |
|
|
578 | continue with step *. |
466 | |
579 | |
467 | Example: queue some jobs and then loop until no events are outsanding |
580 | Example: Queue some jobs and then loop until no events are outstanding |
468 | anymore. |
581 | anymore. |
469 | |
582 | |
470 | ... queue jobs here, make sure they register event watchers as long |
583 | ... queue jobs here, make sure they register event watchers as long |
471 | ... as they still have work to do (even an idle watcher will do..) |
584 | ... as they still have work to do (even an idle watcher will do..) |
472 | ev_loop (my_loop, 0); |
585 | ev_loop (my_loop, 0); |
… | |
… | |
492 | visible to the libev user and should not keep C<ev_loop> from exiting if |
605 | visible to the libev user and should not keep C<ev_loop> from exiting if |
493 | no event watchers registered by it are active. It is also an excellent |
606 | no event watchers registered by it are active. It is also an excellent |
494 | way to do this for generic recurring timers or from within third-party |
607 | way to do this for generic recurring timers or from within third-party |
495 | libraries. Just remember to I<unref after start> and I<ref before stop>. |
608 | libraries. Just remember to I<unref after start> and I<ref before stop>. |
496 | |
609 | |
497 | Example: create a signal watcher, but keep it from keeping C<ev_loop> |
610 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
498 | running when nothing else is active. |
611 | running when nothing else is active. |
499 | |
612 | |
500 | struct dv_signal exitsig; |
613 | struct ev_signal exitsig; |
501 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
614 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
502 | ev_signal_start (myloop, &exitsig); |
615 | ev_signal_start (loop, &exitsig); |
503 | evf_unref (myloop); |
616 | evf_unref (loop); |
504 | |
617 | |
505 | Example: for some weird reason, unregister the above signal handler again. |
618 | Example: For some weird reason, unregister the above signal handler again. |
506 | |
619 | |
507 | ev_ref (myloop); |
620 | ev_ref (loop); |
508 | ev_signal_stop (myloop, &exitsig); |
621 | ev_signal_stop (loop, &exitsig); |
|
|
622 | |
|
|
623 | =item ev_set_io_collect_interval (loop, ev_tstamp interval) |
|
|
624 | |
|
|
625 | =item ev_set_timeout_collect_interval (loop, ev_tstamp interval) |
|
|
626 | |
|
|
627 | These advanced functions influence the time that libev will spend waiting |
|
|
628 | for events. Both are by default C<0>, meaning that libev will try to |
|
|
629 | invoke timer/periodic callbacks and I/O callbacks with minimum latency. |
|
|
630 | |
|
|
631 | Setting these to a higher value (the C<interval> I<must> be >= C<0>) |
|
|
632 | allows libev to delay invocation of I/O and timer/periodic callbacks to |
|
|
633 | increase efficiency of loop iterations. |
|
|
634 | |
|
|
635 | The background is that sometimes your program runs just fast enough to |
|
|
636 | handle one (or very few) event(s) per loop iteration. While this makes |
|
|
637 | the program responsive, it also wastes a lot of CPU time to poll for new |
|
|
638 | events, especially with backends like C<select ()> which have a high |
|
|
639 | overhead for the actual polling but can deliver many events at once. |
|
|
640 | |
|
|
641 | By setting a higher I<io collect interval> you allow libev to spend more |
|
|
642 | time collecting I/O events, so you can handle more events per iteration, |
|
|
643 | at the cost of increasing latency. Timeouts (both C<ev_periodic> and |
|
|
644 | C<ev_timer>) will be not affected. Setting this to a non-null value will |
|
|
645 | introduce an additional C<ev_sleep ()> call into most loop iterations. |
|
|
646 | |
|
|
647 | Likewise, by setting a higher I<timeout collect interval> you allow libev |
|
|
648 | to spend more time collecting timeouts, at the expense of increased |
|
|
649 | latency (the watcher callback will be called later). C<ev_io> watchers |
|
|
650 | will not be affected. Setting this to a non-null value will not introduce |
|
|
651 | any overhead in libev. |
|
|
652 | |
|
|
653 | Many (busy) programs can usually benefit by setting the io collect |
|
|
654 | interval to a value near C<0.1> or so, which is often enough for |
|
|
655 | interactive servers (of course not for games), likewise for timeouts. It |
|
|
656 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
|
|
657 | as this approsaches the timing granularity of most systems. |
509 | |
658 | |
510 | =back |
659 | =back |
511 | |
660 | |
512 | |
661 | |
513 | =head1 ANATOMY OF A WATCHER |
662 | =head1 ANATOMY OF A WATCHER |
… | |
… | |
693 | =item bool ev_is_pending (ev_TYPE *watcher) |
842 | =item bool ev_is_pending (ev_TYPE *watcher) |
694 | |
843 | |
695 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
844 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
696 | events but its callback has not yet been invoked). As long as a watcher |
845 | events but its callback has not yet been invoked). As long as a watcher |
697 | is pending (but not active) you must not call an init function on it (but |
846 | is pending (but not active) you must not call an init function on it (but |
698 | C<ev_TYPE_set> is safe) and you must make sure the watcher is available to |
847 | C<ev_TYPE_set> is safe), you must not change its priority, and you must |
699 | libev (e.g. you cnanot C<free ()> it). |
848 | make sure the watcher is available to libev (e.g. you cannot C<free ()> |
|
|
849 | it). |
700 | |
850 | |
701 | =item callback = ev_cb (ev_TYPE *watcher) |
851 | =item callback ev_cb (ev_TYPE *watcher) |
702 | |
852 | |
703 | Returns the callback currently set on the watcher. |
853 | Returns the callback currently set on the watcher. |
704 | |
854 | |
705 | =item ev_cb_set (ev_TYPE *watcher, callback) |
855 | =item ev_cb_set (ev_TYPE *watcher, callback) |
706 | |
856 | |
707 | Change the callback. You can change the callback at virtually any time |
857 | Change the callback. You can change the callback at virtually any time |
708 | (modulo threads). |
858 | (modulo threads). |
|
|
859 | |
|
|
860 | =item ev_set_priority (ev_TYPE *watcher, priority) |
|
|
861 | |
|
|
862 | =item int ev_priority (ev_TYPE *watcher) |
|
|
863 | |
|
|
864 | Set and query the priority of the watcher. The priority is a small |
|
|
865 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
|
|
866 | (default: C<-2>). Pending watchers with higher priority will be invoked |
|
|
867 | before watchers with lower priority, but priority will not keep watchers |
|
|
868 | from being executed (except for C<ev_idle> watchers). |
|
|
869 | |
|
|
870 | This means that priorities are I<only> used for ordering callback |
|
|
871 | invocation after new events have been received. This is useful, for |
|
|
872 | example, to reduce latency after idling, or more often, to bind two |
|
|
873 | watchers on the same event and make sure one is called first. |
|
|
874 | |
|
|
875 | If you need to suppress invocation when higher priority events are pending |
|
|
876 | you need to look at C<ev_idle> watchers, which provide this functionality. |
|
|
877 | |
|
|
878 | You I<must not> change the priority of a watcher as long as it is active or |
|
|
879 | pending. |
|
|
880 | |
|
|
881 | The default priority used by watchers when no priority has been set is |
|
|
882 | always C<0>, which is supposed to not be too high and not be too low :). |
|
|
883 | |
|
|
884 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
|
|
885 | fine, as long as you do not mind that the priority value you query might |
|
|
886 | or might not have been adjusted to be within valid range. |
|
|
887 | |
|
|
888 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
|
|
889 | |
|
|
890 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
|
|
891 | C<loop> nor C<revents> need to be valid as long as the watcher callback |
|
|
892 | can deal with that fact. |
|
|
893 | |
|
|
894 | =item int ev_clear_pending (loop, ev_TYPE *watcher) |
|
|
895 | |
|
|
896 | If the watcher is pending, this function returns clears its pending status |
|
|
897 | and returns its C<revents> bitset (as if its callback was invoked). If the |
|
|
898 | watcher isn't pending it does nothing and returns C<0>. |
709 | |
899 | |
710 | =back |
900 | =back |
711 | |
901 | |
712 | |
902 | |
713 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
903 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
… | |
… | |
734 | { |
924 | { |
735 | struct my_io *w = (struct my_io *)w_; |
925 | struct my_io *w = (struct my_io *)w_; |
736 | ... |
926 | ... |
737 | } |
927 | } |
738 | |
928 | |
739 | More interesting and less C-conformant ways of catsing your callback type |
929 | More interesting and less C-conformant ways of casting your callback type |
740 | have been omitted.... |
930 | instead have been omitted. |
|
|
931 | |
|
|
932 | Another common scenario is having some data structure with multiple |
|
|
933 | watchers: |
|
|
934 | |
|
|
935 | struct my_biggy |
|
|
936 | { |
|
|
937 | int some_data; |
|
|
938 | ev_timer t1; |
|
|
939 | ev_timer t2; |
|
|
940 | } |
|
|
941 | |
|
|
942 | In this case getting the pointer to C<my_biggy> is a bit more complicated, |
|
|
943 | you need to use C<offsetof>: |
|
|
944 | |
|
|
945 | #include <stddef.h> |
|
|
946 | |
|
|
947 | static void |
|
|
948 | t1_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
949 | { |
|
|
950 | struct my_biggy big = (struct my_biggy * |
|
|
951 | (((char *)w) - offsetof (struct my_biggy, t1)); |
|
|
952 | } |
|
|
953 | |
|
|
954 | static void |
|
|
955 | t2_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
956 | { |
|
|
957 | struct my_biggy big = (struct my_biggy * |
|
|
958 | (((char *)w) - offsetof (struct my_biggy, t2)); |
|
|
959 | } |
741 | |
960 | |
742 | |
961 | |
743 | =head1 WATCHER TYPES |
962 | =head1 WATCHER TYPES |
744 | |
963 | |
745 | This section describes each watcher in detail, but will not repeat |
964 | This section describes each watcher in detail, but will not repeat |
… | |
… | |
769 | In general you can register as many read and/or write event watchers per |
988 | In general you can register as many read and/or write event watchers per |
770 | fd as you want (as long as you don't confuse yourself). Setting all file |
989 | fd as you want (as long as you don't confuse yourself). Setting all file |
771 | descriptors to non-blocking mode is also usually a good idea (but not |
990 | descriptors to non-blocking mode is also usually a good idea (but not |
772 | required if you know what you are doing). |
991 | required if you know what you are doing). |
773 | |
992 | |
774 | You have to be careful with dup'ed file descriptors, though. Some backends |
|
|
775 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
|
|
776 | descriptors correctly if you register interest in two or more fds pointing |
|
|
777 | to the same underlying file/socket/etc. description (that is, they share |
|
|
778 | the same underlying "file open"). |
|
|
779 | |
|
|
780 | If you must do this, then force the use of a known-to-be-good backend |
993 | If you must do this, then force the use of a known-to-be-good backend |
781 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
994 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
782 | C<EVBACKEND_POLL>). |
995 | C<EVBACKEND_POLL>). |
783 | |
996 | |
784 | Another thing you have to watch out for is that it is quite easy to |
997 | Another thing you have to watch out for is that it is quite easy to |
… | |
… | |
790 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
1003 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
791 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
1004 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
792 | |
1005 | |
793 | If you cannot run the fd in non-blocking mode (for example you should not |
1006 | If you cannot run the fd in non-blocking mode (for example you should not |
794 | play around with an Xlib connection), then you have to seperately re-test |
1007 | play around with an Xlib connection), then you have to seperately re-test |
795 | wether a file descriptor is really ready with a known-to-be good interface |
1008 | whether a file descriptor is really ready with a known-to-be good interface |
796 | such as poll (fortunately in our Xlib example, Xlib already does this on |
1009 | such as poll (fortunately in our Xlib example, Xlib already does this on |
797 | its own, so its quite safe to use). |
1010 | its own, so its quite safe to use). |
|
|
1011 | |
|
|
1012 | =head3 The special problem of disappearing file descriptors |
|
|
1013 | |
|
|
1014 | Some backends (e.g. kqueue, epoll) need to be told about closing a file |
|
|
1015 | descriptor (either by calling C<close> explicitly or by any other means, |
|
|
1016 | such as C<dup>). The reason is that you register interest in some file |
|
|
1017 | descriptor, but when it goes away, the operating system will silently drop |
|
|
1018 | this interest. If another file descriptor with the same number then is |
|
|
1019 | registered with libev, there is no efficient way to see that this is, in |
|
|
1020 | fact, a different file descriptor. |
|
|
1021 | |
|
|
1022 | To avoid having to explicitly tell libev about such cases, libev follows |
|
|
1023 | the following policy: Each time C<ev_io_set> is being called, libev |
|
|
1024 | will assume that this is potentially a new file descriptor, otherwise |
|
|
1025 | it is assumed that the file descriptor stays the same. That means that |
|
|
1026 | you I<have> to call C<ev_io_set> (or C<ev_io_init>) when you change the |
|
|
1027 | descriptor even if the file descriptor number itself did not change. |
|
|
1028 | |
|
|
1029 | This is how one would do it normally anyway, the important point is that |
|
|
1030 | the libev application should not optimise around libev but should leave |
|
|
1031 | optimisations to libev. |
|
|
1032 | |
|
|
1033 | =head3 The special problem of dup'ed file descriptors |
|
|
1034 | |
|
|
1035 | Some backends (e.g. epoll), cannot register events for file descriptors, |
|
|
1036 | but only events for the underlying file descriptions. That means when you |
|
|
1037 | have C<dup ()>'ed file descriptors or weirder constellations, and register |
|
|
1038 | events for them, only one file descriptor might actually receive events. |
|
|
1039 | |
|
|
1040 | There is no workaround possible except not registering events |
|
|
1041 | for potentially C<dup ()>'ed file descriptors, or to resort to |
|
|
1042 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
|
|
1043 | |
|
|
1044 | =head3 The special problem of fork |
|
|
1045 | |
|
|
1046 | Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit |
|
|
1047 | useless behaviour. Libev fully supports fork, but needs to be told about |
|
|
1048 | it in the child. |
|
|
1049 | |
|
|
1050 | To support fork in your programs, you either have to call |
|
|
1051 | C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child, |
|
|
1052 | enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or |
|
|
1053 | C<EVBACKEND_POLL>. |
|
|
1054 | |
|
|
1055 | |
|
|
1056 | =head3 Watcher-Specific Functions |
798 | |
1057 | |
799 | =over 4 |
1058 | =over 4 |
800 | |
1059 | |
801 | =item ev_io_init (ev_io *, callback, int fd, int events) |
1060 | =item ev_io_init (ev_io *, callback, int fd, int events) |
802 | |
1061 | |
… | |
… | |
814 | |
1073 | |
815 | The events being watched. |
1074 | The events being watched. |
816 | |
1075 | |
817 | =back |
1076 | =back |
818 | |
1077 | |
|
|
1078 | =head3 Examples |
|
|
1079 | |
819 | Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well |
1080 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
820 | readable, but only once. Since it is likely line-buffered, you could |
1081 | readable, but only once. Since it is likely line-buffered, you could |
821 | attempt to read a whole line in the callback: |
1082 | attempt to read a whole line in the callback. |
822 | |
1083 | |
823 | static void |
1084 | static void |
824 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1085 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
825 | { |
1086 | { |
826 | ev_io_stop (loop, w); |
1087 | ev_io_stop (loop, w); |
… | |
… | |
856 | |
1117 | |
857 | The callback is guarenteed to be invoked only when its timeout has passed, |
1118 | The callback is guarenteed to be invoked only when its timeout has passed, |
858 | but if multiple timers become ready during the same loop iteration then |
1119 | but if multiple timers become ready during the same loop iteration then |
859 | order of execution is undefined. |
1120 | order of execution is undefined. |
860 | |
1121 | |
|
|
1122 | =head3 Watcher-Specific Functions and Data Members |
|
|
1123 | |
861 | =over 4 |
1124 | =over 4 |
862 | |
1125 | |
863 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
1126 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
864 | |
1127 | |
865 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
1128 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
… | |
… | |
878 | =item ev_timer_again (loop) |
1141 | =item ev_timer_again (loop) |
879 | |
1142 | |
880 | This will act as if the timer timed out and restart it again if it is |
1143 | This will act as if the timer timed out and restart it again if it is |
881 | repeating. The exact semantics are: |
1144 | repeating. The exact semantics are: |
882 | |
1145 | |
|
|
1146 | If the timer is pending, its pending status is cleared. |
|
|
1147 | |
883 | If the timer is started but nonrepeating, stop it. |
1148 | If the timer is started but nonrepeating, stop it (as if it timed out). |
884 | |
1149 | |
885 | If the timer is repeating, either start it if necessary (with the repeat |
1150 | If the timer is repeating, either start it if necessary (with the |
886 | value), or reset the running timer to the repeat value. |
1151 | C<repeat> value), or reset the running timer to the C<repeat> value. |
887 | |
1152 | |
888 | This sounds a bit complicated, but here is a useful and typical |
1153 | This sounds a bit complicated, but here is a useful and typical |
889 | example: Imagine you have a tcp connection and you want a so-called |
1154 | example: Imagine you have a tcp connection and you want a so-called idle |
890 | idle timeout, that is, you want to be called when there have been, |
1155 | timeout, that is, you want to be called when there have been, say, 60 |
891 | say, 60 seconds of inactivity on the socket. The easiest way to do |
1156 | seconds of inactivity on the socket. The easiest way to do this is to |
892 | this is to configure an C<ev_timer> with C<after>=C<repeat>=C<60> and calling |
1157 | configure an C<ev_timer> with a C<repeat> value of C<60> and then call |
893 | C<ev_timer_again> each time you successfully read or write some data. If |
1158 | C<ev_timer_again> each time you successfully read or write some data. If |
894 | you go into an idle state where you do not expect data to travel on the |
1159 | you go into an idle state where you do not expect data to travel on the |
895 | socket, you can stop the timer, and again will automatically restart it if |
1160 | socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will |
896 | need be. |
1161 | automatically restart it if need be. |
897 | |
1162 | |
898 | You can also ignore the C<after> value and C<ev_timer_start> altogether |
1163 | That means you can ignore the C<after> value and C<ev_timer_start> |
899 | and only ever use the C<repeat> value: |
1164 | altogether and only ever use the C<repeat> value and C<ev_timer_again>: |
900 | |
1165 | |
901 | ev_timer_init (timer, callback, 0., 5.); |
1166 | ev_timer_init (timer, callback, 0., 5.); |
902 | ev_timer_again (loop, timer); |
1167 | ev_timer_again (loop, timer); |
903 | ... |
1168 | ... |
904 | timer->again = 17.; |
1169 | timer->again = 17.; |
905 | ev_timer_again (loop, timer); |
1170 | ev_timer_again (loop, timer); |
906 | ... |
1171 | ... |
907 | timer->again = 10.; |
1172 | timer->again = 10.; |
908 | ev_timer_again (loop, timer); |
1173 | ev_timer_again (loop, timer); |
909 | |
1174 | |
910 | This is more efficient then stopping/starting the timer eahc time you want |
1175 | This is more slightly efficient then stopping/starting the timer each time |
911 | to modify its timeout value. |
1176 | you want to modify its timeout value. |
912 | |
1177 | |
913 | =item ev_tstamp repeat [read-write] |
1178 | =item ev_tstamp repeat [read-write] |
914 | |
1179 | |
915 | The current C<repeat> value. Will be used each time the watcher times out |
1180 | The current C<repeat> value. Will be used each time the watcher times out |
916 | or C<ev_timer_again> is called and determines the next timeout (if any), |
1181 | or C<ev_timer_again> is called and determines the next timeout (if any), |
917 | which is also when any modifications are taken into account. |
1182 | which is also when any modifications are taken into account. |
918 | |
1183 | |
919 | =back |
1184 | =back |
920 | |
1185 | |
|
|
1186 | =head3 Examples |
|
|
1187 | |
921 | Example: create a timer that fires after 60 seconds. |
1188 | Example: Create a timer that fires after 60 seconds. |
922 | |
1189 | |
923 | static void |
1190 | static void |
924 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1191 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
925 | { |
1192 | { |
926 | .. one minute over, w is actually stopped right here |
1193 | .. one minute over, w is actually stopped right here |
… | |
… | |
928 | |
1195 | |
929 | struct ev_timer mytimer; |
1196 | struct ev_timer mytimer; |
930 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
1197 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
931 | ev_timer_start (loop, &mytimer); |
1198 | ev_timer_start (loop, &mytimer); |
932 | |
1199 | |
933 | Example: create a timeout timer that times out after 10 seconds of |
1200 | Example: Create a timeout timer that times out after 10 seconds of |
934 | inactivity. |
1201 | inactivity. |
935 | |
1202 | |
936 | static void |
1203 | static void |
937 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1204 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
938 | { |
1205 | { |
… | |
… | |
958 | but on wallclock time (absolute time). You can tell a periodic watcher |
1225 | but on wallclock time (absolute time). You can tell a periodic watcher |
959 | to trigger "at" some specific point in time. For example, if you tell a |
1226 | to trigger "at" some specific point in time. For example, if you tell a |
960 | periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now () |
1227 | periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now () |
961 | + 10.>) and then reset your system clock to the last year, then it will |
1228 | + 10.>) and then reset your system clock to the last year, then it will |
962 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
1229 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
963 | roughly 10 seconds later and of course not if you reset your system time |
1230 | roughly 10 seconds later). |
964 | again). |
|
|
965 | |
1231 | |
966 | They can also be used to implement vastly more complex timers, such as |
1232 | They can also be used to implement vastly more complex timers, such as |
967 | triggering an event on eahc midnight, local time. |
1233 | triggering an event on each midnight, local time or other, complicated, |
|
|
1234 | rules. |
968 | |
1235 | |
969 | As with timers, the callback is guarenteed to be invoked only when the |
1236 | As with timers, the callback is guarenteed to be invoked only when the |
970 | time (C<at>) has been passed, but if multiple periodic timers become ready |
1237 | time (C<at>) has been passed, but if multiple periodic timers become ready |
971 | during the same loop iteration then order of execution is undefined. |
1238 | during the same loop iteration then order of execution is undefined. |
972 | |
1239 | |
|
|
1240 | =head3 Watcher-Specific Functions and Data Members |
|
|
1241 | |
973 | =over 4 |
1242 | =over 4 |
974 | |
1243 | |
975 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
1244 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
976 | |
1245 | |
977 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
1246 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
… | |
… | |
979 | Lots of arguments, lets sort it out... There are basically three modes of |
1248 | Lots of arguments, lets sort it out... There are basically three modes of |
980 | operation, and we will explain them from simplest to complex: |
1249 | operation, and we will explain them from simplest to complex: |
981 | |
1250 | |
982 | =over 4 |
1251 | =over 4 |
983 | |
1252 | |
984 | =item * absolute timer (interval = reschedule_cb = 0) |
1253 | =item * absolute timer (at = time, interval = reschedule_cb = 0) |
985 | |
1254 | |
986 | In this configuration the watcher triggers an event at the wallclock time |
1255 | In this configuration the watcher triggers an event at the wallclock time |
987 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
1256 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
988 | that is, if it is to be run at January 1st 2011 then it will run when the |
1257 | that is, if it is to be run at January 1st 2011 then it will run when the |
989 | system time reaches or surpasses this time. |
1258 | system time reaches or surpasses this time. |
990 | |
1259 | |
991 | =item * non-repeating interval timer (interval > 0, reschedule_cb = 0) |
1260 | =item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
992 | |
1261 | |
993 | In this mode the watcher will always be scheduled to time out at the next |
1262 | In this mode the watcher will always be scheduled to time out at the next |
994 | C<at + N * interval> time (for some integer N) and then repeat, regardless |
1263 | C<at + N * interval> time (for some integer N, which can also be negative) |
995 | of any time jumps. |
1264 | and then repeat, regardless of any time jumps. |
996 | |
1265 | |
997 | This can be used to create timers that do not drift with respect to system |
1266 | This can be used to create timers that do not drift with respect to system |
998 | time: |
1267 | time: |
999 | |
1268 | |
1000 | ev_periodic_set (&periodic, 0., 3600., 0); |
1269 | ev_periodic_set (&periodic, 0., 3600., 0); |
… | |
… | |
1006 | |
1275 | |
1007 | Another way to think about it (for the mathematically inclined) is that |
1276 | Another way to think about it (for the mathematically inclined) is that |
1008 | C<ev_periodic> will try to run the callback in this mode at the next possible |
1277 | C<ev_periodic> will try to run the callback in this mode at the next possible |
1009 | time where C<time = at (mod interval)>, regardless of any time jumps. |
1278 | time where C<time = at (mod interval)>, regardless of any time jumps. |
1010 | |
1279 | |
|
|
1280 | For numerical stability it is preferable that the C<at> value is near |
|
|
1281 | C<ev_now ()> (the current time), but there is no range requirement for |
|
|
1282 | this value. |
|
|
1283 | |
1011 | =item * manual reschedule mode (reschedule_cb = callback) |
1284 | =item * manual reschedule mode (at and interval ignored, reschedule_cb = callback) |
1012 | |
1285 | |
1013 | In this mode the values for C<interval> and C<at> are both being |
1286 | In this mode the values for C<interval> and C<at> are both being |
1014 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1287 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1015 | reschedule callback will be called with the watcher as first, and the |
1288 | reschedule callback will be called with the watcher as first, and the |
1016 | current time as second argument. |
1289 | current time as second argument. |
1017 | |
1290 | |
1018 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
1291 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
1019 | ever, or make any event loop modifications>. If you need to stop it, |
1292 | ever, or make any event loop modifications>. If you need to stop it, |
1020 | return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by |
1293 | return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by |
1021 | starting a prepare watcher). |
1294 | starting an C<ev_prepare> watcher, which is legal). |
1022 | |
1295 | |
1023 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1296 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1024 | ev_tstamp now)>, e.g.: |
1297 | ev_tstamp now)>, e.g.: |
1025 | |
1298 | |
1026 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
1299 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
… | |
… | |
1049 | Simply stops and restarts the periodic watcher again. This is only useful |
1322 | Simply stops and restarts the periodic watcher again. This is only useful |
1050 | when you changed some parameters or the reschedule callback would return |
1323 | when you changed some parameters or the reschedule callback would return |
1051 | a different time than the last time it was called (e.g. in a crond like |
1324 | a different time than the last time it was called (e.g. in a crond like |
1052 | program when the crontabs have changed). |
1325 | program when the crontabs have changed). |
1053 | |
1326 | |
|
|
1327 | =item ev_tstamp offset [read-write] |
|
|
1328 | |
|
|
1329 | When repeating, this contains the offset value, otherwise this is the |
|
|
1330 | absolute point in time (the C<at> value passed to C<ev_periodic_set>). |
|
|
1331 | |
|
|
1332 | Can be modified any time, but changes only take effect when the periodic |
|
|
1333 | timer fires or C<ev_periodic_again> is being called. |
|
|
1334 | |
1054 | =item ev_tstamp interval [read-write] |
1335 | =item ev_tstamp interval [read-write] |
1055 | |
1336 | |
1056 | The current interval value. Can be modified any time, but changes only |
1337 | The current interval value. Can be modified any time, but changes only |
1057 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
1338 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
1058 | called. |
1339 | called. |
… | |
… | |
1061 | |
1342 | |
1062 | The current reschedule callback, or C<0>, if this functionality is |
1343 | The current reschedule callback, or C<0>, if this functionality is |
1063 | switched off. Can be changed any time, but changes only take effect when |
1344 | switched off. Can be changed any time, but changes only take effect when |
1064 | the periodic timer fires or C<ev_periodic_again> is being called. |
1345 | the periodic timer fires or C<ev_periodic_again> is being called. |
1065 | |
1346 | |
|
|
1347 | =item ev_tstamp at [read-only] |
|
|
1348 | |
|
|
1349 | When active, contains the absolute time that the watcher is supposed to |
|
|
1350 | trigger next. |
|
|
1351 | |
1066 | =back |
1352 | =back |
1067 | |
1353 | |
|
|
1354 | =head3 Examples |
|
|
1355 | |
1068 | Example: call a callback every hour, or, more precisely, whenever the |
1356 | Example: Call a callback every hour, or, more precisely, whenever the |
1069 | system clock is divisible by 3600. The callback invocation times have |
1357 | system clock is divisible by 3600. The callback invocation times have |
1070 | potentially a lot of jittering, but good long-term stability. |
1358 | potentially a lot of jittering, but good long-term stability. |
1071 | |
1359 | |
1072 | static void |
1360 | static void |
1073 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1361 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
… | |
… | |
1077 | |
1365 | |
1078 | struct ev_periodic hourly_tick; |
1366 | struct ev_periodic hourly_tick; |
1079 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1367 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1080 | ev_periodic_start (loop, &hourly_tick); |
1368 | ev_periodic_start (loop, &hourly_tick); |
1081 | |
1369 | |
1082 | Example: the same as above, but use a reschedule callback to do it: |
1370 | Example: The same as above, but use a reschedule callback to do it: |
1083 | |
1371 | |
1084 | #include <math.h> |
1372 | #include <math.h> |
1085 | |
1373 | |
1086 | static ev_tstamp |
1374 | static ev_tstamp |
1087 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
1375 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
… | |
… | |
1089 | return fmod (now, 3600.) + 3600.; |
1377 | return fmod (now, 3600.) + 3600.; |
1090 | } |
1378 | } |
1091 | |
1379 | |
1092 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1380 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1093 | |
1381 | |
1094 | Example: call a callback every hour, starting now: |
1382 | Example: Call a callback every hour, starting now: |
1095 | |
1383 | |
1096 | struct ev_periodic hourly_tick; |
1384 | struct ev_periodic hourly_tick; |
1097 | ev_periodic_init (&hourly_tick, clock_cb, |
1385 | ev_periodic_init (&hourly_tick, clock_cb, |
1098 | fmod (ev_now (loop), 3600.), 3600., 0); |
1386 | fmod (ev_now (loop), 3600.), 3600., 0); |
1099 | ev_periodic_start (loop, &hourly_tick); |
1387 | ev_periodic_start (loop, &hourly_tick); |
… | |
… | |
1111 | with the kernel (thus it coexists with your own signal handlers as long |
1399 | with the kernel (thus it coexists with your own signal handlers as long |
1112 | as you don't register any with libev). Similarly, when the last signal |
1400 | as you don't register any with libev). Similarly, when the last signal |
1113 | watcher for a signal is stopped libev will reset the signal handler to |
1401 | watcher for a signal is stopped libev will reset the signal handler to |
1114 | SIG_DFL (regardless of what it was set to before). |
1402 | SIG_DFL (regardless of what it was set to before). |
1115 | |
1403 | |
|
|
1404 | =head3 Watcher-Specific Functions and Data Members |
|
|
1405 | |
1116 | =over 4 |
1406 | =over 4 |
1117 | |
1407 | |
1118 | =item ev_signal_init (ev_signal *, callback, int signum) |
1408 | =item ev_signal_init (ev_signal *, callback, int signum) |
1119 | |
1409 | |
1120 | =item ev_signal_set (ev_signal *, int signum) |
1410 | =item ev_signal_set (ev_signal *, int signum) |
… | |
… | |
1131 | |
1421 | |
1132 | =head2 C<ev_child> - watch out for process status changes |
1422 | =head2 C<ev_child> - watch out for process status changes |
1133 | |
1423 | |
1134 | Child watchers trigger when your process receives a SIGCHLD in response to |
1424 | Child watchers trigger when your process receives a SIGCHLD in response to |
1135 | some child status changes (most typically when a child of yours dies). |
1425 | some child status changes (most typically when a child of yours dies). |
|
|
1426 | |
|
|
1427 | =head3 Watcher-Specific Functions and Data Members |
1136 | |
1428 | |
1137 | =over 4 |
1429 | =over 4 |
1138 | |
1430 | |
1139 | =item ev_child_init (ev_child *, callback, int pid) |
1431 | =item ev_child_init (ev_child *, callback, int pid) |
1140 | |
1432 | |
… | |
… | |
1160 | The process exit/trace status caused by C<rpid> (see your systems |
1452 | The process exit/trace status caused by C<rpid> (see your systems |
1161 | C<waitpid> and C<sys/wait.h> documentation for details). |
1453 | C<waitpid> and C<sys/wait.h> documentation for details). |
1162 | |
1454 | |
1163 | =back |
1455 | =back |
1164 | |
1456 | |
|
|
1457 | =head3 Examples |
|
|
1458 | |
1165 | Example: try to exit cleanly on SIGINT and SIGTERM. |
1459 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
1166 | |
1460 | |
1167 | static void |
1461 | static void |
1168 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1462 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1169 | { |
1463 | { |
1170 | ev_unloop (loop, EVUNLOOP_ALL); |
1464 | ev_unloop (loop, EVUNLOOP_ALL); |
… | |
… | |
1185 | not exist" is a status change like any other. The condition "path does |
1479 | not exist" is a status change like any other. The condition "path does |
1186 | not exist" is signified by the C<st_nlink> field being zero (which is |
1480 | not exist" is signified by the C<st_nlink> field being zero (which is |
1187 | otherwise always forced to be at least one) and all the other fields of |
1481 | otherwise always forced to be at least one) and all the other fields of |
1188 | the stat buffer having unspecified contents. |
1482 | the stat buffer having unspecified contents. |
1189 | |
1483 | |
|
|
1484 | The path I<should> be absolute and I<must not> end in a slash. If it is |
|
|
1485 | relative and your working directory changes, the behaviour is undefined. |
|
|
1486 | |
1190 | Since there is no standard to do this, the portable implementation simply |
1487 | Since there is no standard to do this, the portable implementation simply |
1191 | calls C<stat (2)> regulalry on the path to see if it changed somehow. You |
1488 | calls C<stat (2)> regularly on the path to see if it changed somehow. You |
1192 | can specify a recommended polling interval for this case. If you specify |
1489 | can specify a recommended polling interval for this case. If you specify |
1193 | a polling interval of C<0> (highly recommended!) then a I<suitable, |
1490 | a polling interval of C<0> (highly recommended!) then a I<suitable, |
1194 | unspecified default> value will be used (which you can expect to be around |
1491 | unspecified default> value will be used (which you can expect to be around |
1195 | five seconds, although this might change dynamically). Libev will also |
1492 | five seconds, although this might change dynamically). Libev will also |
1196 | impose a minimum interval which is currently around C<0.1>, but thats |
1493 | impose a minimum interval which is currently around C<0.1>, but thats |
… | |
… | |
1198 | |
1495 | |
1199 | This watcher type is not meant for massive numbers of stat watchers, |
1496 | This watcher type is not meant for massive numbers of stat watchers, |
1200 | as even with OS-supported change notifications, this can be |
1497 | as even with OS-supported change notifications, this can be |
1201 | resource-intensive. |
1498 | resource-intensive. |
1202 | |
1499 | |
1203 | At the time of this writing, no specific OS backends are implemented, but |
1500 | At the time of this writing, only the Linux inotify interface is |
1204 | if demand increases, at least a kqueue and inotify backend will be added. |
1501 | implemented (implementing kqueue support is left as an exercise for the |
|
|
1502 | reader). Inotify will be used to give hints only and should not change the |
|
|
1503 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
|
|
1504 | to fall back to regular polling again even with inotify, but changes are |
|
|
1505 | usually detected immediately, and if the file exists there will be no |
|
|
1506 | polling. |
|
|
1507 | |
|
|
1508 | =head3 Inotify |
|
|
1509 | |
|
|
1510 | When C<inotify (7)> support has been compiled into libev (generally only |
|
|
1511 | available on Linux) and present at runtime, it will be used to speed up |
|
|
1512 | change detection where possible. The inotify descriptor will be created lazily |
|
|
1513 | when the first C<ev_stat> watcher is being started. |
|
|
1514 | |
|
|
1515 | Inotify presense does not change the semantics of C<ev_stat> watchers |
|
|
1516 | except that changes might be detected earlier, and in some cases, to avoid |
|
|
1517 | making regular C<stat> calls. Even in the presense of inotify support |
|
|
1518 | there are many cases where libev has to resort to regular C<stat> polling. |
|
|
1519 | |
|
|
1520 | (There is no support for kqueue, as apparently it cannot be used to |
|
|
1521 | implement this functionality, due to the requirement of having a file |
|
|
1522 | descriptor open on the object at all times). |
|
|
1523 | |
|
|
1524 | =head3 The special problem of stat time resolution |
|
|
1525 | |
|
|
1526 | The C<stat ()> syscall only supports full-second resolution portably, and |
|
|
1527 | even on systems where the resolution is higher, many filesystems still |
|
|
1528 | only support whole seconds. |
|
|
1529 | |
|
|
1530 | That means that, if the time is the only thing that changes, you might |
|
|
1531 | miss updates: on the first update, C<ev_stat> detects a change and calls |
|
|
1532 | your callback, which does something. When there is another update within |
|
|
1533 | the same second, C<ev_stat> will be unable to detect it. |
|
|
1534 | |
|
|
1535 | The solution to this is to delay acting on a change for a second (or till |
|
|
1536 | the next second boundary), using a roughly one-second delay C<ev_timer> |
|
|
1537 | (C<ev_timer_set (w, 0., 1.01); ev_timer_again (loop, w)>). The C<.01> |
|
|
1538 | is added to work around small timing inconsistencies of some operating |
|
|
1539 | systems. |
|
|
1540 | |
|
|
1541 | =head3 Watcher-Specific Functions and Data Members |
1205 | |
1542 | |
1206 | =over 4 |
1543 | =over 4 |
1207 | |
1544 | |
1208 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1545 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1209 | |
1546 | |
… | |
… | |
1245 | =item const char *path [read-only] |
1582 | =item const char *path [read-only] |
1246 | |
1583 | |
1247 | The filesystem path that is being watched. |
1584 | The filesystem path that is being watched. |
1248 | |
1585 | |
1249 | =back |
1586 | =back |
|
|
1587 | |
|
|
1588 | =head3 Examples |
1250 | |
1589 | |
1251 | Example: Watch C</etc/passwd> for attribute changes. |
1590 | Example: Watch C</etc/passwd> for attribute changes. |
1252 | |
1591 | |
1253 | static void |
1592 | static void |
1254 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
1593 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
… | |
… | |
1267 | } |
1606 | } |
1268 | |
1607 | |
1269 | ... |
1608 | ... |
1270 | ev_stat passwd; |
1609 | ev_stat passwd; |
1271 | |
1610 | |
1272 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd"); |
1611 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.); |
1273 | ev_stat_start (loop, &passwd); |
1612 | ev_stat_start (loop, &passwd); |
1274 | |
1613 | |
|
|
1614 | Example: Like above, but additionally use a one-second delay so we do not |
|
|
1615 | miss updates (however, frequent updates will delay processing, too, so |
|
|
1616 | one might do the work both on C<ev_stat> callback invocation I<and> on |
|
|
1617 | C<ev_timer> callback invocation). |
|
|
1618 | |
|
|
1619 | static ev_stat passwd; |
|
|
1620 | static ev_timer timer; |
|
|
1621 | |
|
|
1622 | static void |
|
|
1623 | timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1624 | { |
|
|
1625 | ev_timer_stop (EV_A_ w); |
|
|
1626 | |
|
|
1627 | /* now it's one second after the most recent passwd change */ |
|
|
1628 | } |
|
|
1629 | |
|
|
1630 | static void |
|
|
1631 | stat_cb (EV_P_ ev_stat *w, int revents) |
|
|
1632 | { |
|
|
1633 | /* reset the one-second timer */ |
|
|
1634 | ev_timer_again (EV_A_ &timer); |
|
|
1635 | } |
|
|
1636 | |
|
|
1637 | ... |
|
|
1638 | ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); |
|
|
1639 | ev_stat_start (loop, &passwd); |
|
|
1640 | ev_timer_init (&timer, timer_cb, 0., 1.01); |
|
|
1641 | |
1275 | |
1642 | |
1276 | =head2 C<ev_idle> - when you've got nothing better to do... |
1643 | =head2 C<ev_idle> - when you've got nothing better to do... |
1277 | |
1644 | |
1278 | Idle watchers trigger events when there are no other events are pending |
1645 | Idle watchers trigger events when no other events of the same or higher |
1279 | (prepare, check and other idle watchers do not count). That is, as long |
1646 | priority are pending (prepare, check and other idle watchers do not |
1280 | as your process is busy handling sockets or timeouts (or even signals, |
1647 | count). |
1281 | imagine) it will not be triggered. But when your process is idle all idle |
1648 | |
1282 | watchers are being called again and again, once per event loop iteration - |
1649 | That is, as long as your process is busy handling sockets or timeouts |
|
|
1650 | (or even signals, imagine) of the same or higher priority it will not be |
|
|
1651 | triggered. But when your process is idle (or only lower-priority watchers |
|
|
1652 | are pending), the idle watchers are being called once per event loop |
1283 | until stopped, that is, or your process receives more events and becomes |
1653 | iteration - until stopped, that is, or your process receives more events |
1284 | busy. |
1654 | and becomes busy again with higher priority stuff. |
1285 | |
1655 | |
1286 | The most noteworthy effect is that as long as any idle watchers are |
1656 | The most noteworthy effect is that as long as any idle watchers are |
1287 | active, the process will not block when waiting for new events. |
1657 | active, the process will not block when waiting for new events. |
1288 | |
1658 | |
1289 | Apart from keeping your process non-blocking (which is a useful |
1659 | Apart from keeping your process non-blocking (which is a useful |
1290 | effect on its own sometimes), idle watchers are a good place to do |
1660 | effect on its own sometimes), idle watchers are a good place to do |
1291 | "pseudo-background processing", or delay processing stuff to after the |
1661 | "pseudo-background processing", or delay processing stuff to after the |
1292 | event loop has handled all outstanding events. |
1662 | event loop has handled all outstanding events. |
1293 | |
1663 | |
|
|
1664 | =head3 Watcher-Specific Functions and Data Members |
|
|
1665 | |
1294 | =over 4 |
1666 | =over 4 |
1295 | |
1667 | |
1296 | =item ev_idle_init (ev_signal *, callback) |
1668 | =item ev_idle_init (ev_signal *, callback) |
1297 | |
1669 | |
1298 | Initialises and configures the idle watcher - it has no parameters of any |
1670 | Initialises and configures the idle watcher - it has no parameters of any |
1299 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1671 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1300 | believe me. |
1672 | believe me. |
1301 | |
1673 | |
1302 | =back |
1674 | =back |
1303 | |
1675 | |
|
|
1676 | =head3 Examples |
|
|
1677 | |
1304 | Example: dynamically allocate an C<ev_idle>, start it, and in the |
1678 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1305 | callback, free it. Alos, use no error checking, as usual. |
1679 | callback, free it. Also, use no error checking, as usual. |
1306 | |
1680 | |
1307 | static void |
1681 | static void |
1308 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1682 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1309 | { |
1683 | { |
1310 | free (w); |
1684 | free (w); |
… | |
… | |
1355 | with priority higher than or equal to the event loop and one coroutine |
1729 | with priority higher than or equal to the event loop and one coroutine |
1356 | of lower priority, but only once, using idle watchers to keep the event |
1730 | of lower priority, but only once, using idle watchers to keep the event |
1357 | loop from blocking if lower-priority coroutines are active, thus mapping |
1731 | loop from blocking if lower-priority coroutines are active, thus mapping |
1358 | low-priority coroutines to idle/background tasks). |
1732 | low-priority coroutines to idle/background tasks). |
1359 | |
1733 | |
|
|
1734 | It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>) |
|
|
1735 | priority, to ensure that they are being run before any other watchers |
|
|
1736 | after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers, |
|
|
1737 | too) should not activate ("feed") events into libev. While libev fully |
|
|
1738 | supports this, they will be called before other C<ev_check> watchers |
|
|
1739 | did their job. As C<ev_check> watchers are often used to embed other |
|
|
1740 | (non-libev) event loops those other event loops might be in an unusable |
|
|
1741 | state until their C<ev_check> watcher ran (always remind yourself to |
|
|
1742 | coexist peacefully with others). |
|
|
1743 | |
|
|
1744 | =head3 Watcher-Specific Functions and Data Members |
|
|
1745 | |
1360 | =over 4 |
1746 | =over 4 |
1361 | |
1747 | |
1362 | =item ev_prepare_init (ev_prepare *, callback) |
1748 | =item ev_prepare_init (ev_prepare *, callback) |
1363 | |
1749 | |
1364 | =item ev_check_init (ev_check *, callback) |
1750 | =item ev_check_init (ev_check *, callback) |
… | |
… | |
1367 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1753 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1368 | macros, but using them is utterly, utterly and completely pointless. |
1754 | macros, but using them is utterly, utterly and completely pointless. |
1369 | |
1755 | |
1370 | =back |
1756 | =back |
1371 | |
1757 | |
1372 | Example: To include a library such as adns, you would add IO watchers |
1758 | =head3 Examples |
1373 | and a timeout watcher in a prepare handler, as required by libadns, and |
1759 | |
|
|
1760 | There are a number of principal ways to embed other event loops or modules |
|
|
1761 | into libev. Here are some ideas on how to include libadns into libev |
|
|
1762 | (there is a Perl module named C<EV::ADNS> that does this, which you could |
|
|
1763 | use for an actually working example. Another Perl module named C<EV::Glib> |
|
|
1764 | embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV |
|
|
1765 | into the Glib event loop). |
|
|
1766 | |
|
|
1767 | Method 1: Add IO watchers and a timeout watcher in a prepare handler, |
1374 | in a check watcher, destroy them and call into libadns. What follows is |
1768 | and in a check watcher, destroy them and call into libadns. What follows |
1375 | pseudo-code only of course: |
1769 | is pseudo-code only of course. This requires you to either use a low |
|
|
1770 | priority for the check watcher or use C<ev_clear_pending> explicitly, as |
|
|
1771 | the callbacks for the IO/timeout watchers might not have been called yet. |
1376 | |
1772 | |
1377 | static ev_io iow [nfd]; |
1773 | static ev_io iow [nfd]; |
1378 | static ev_timer tw; |
1774 | static ev_timer tw; |
1379 | |
1775 | |
1380 | static void |
1776 | static void |
1381 | io_cb (ev_loop *loop, ev_io *w, int revents) |
1777 | io_cb (ev_loop *loop, ev_io *w, int revents) |
1382 | { |
1778 | { |
1383 | // set the relevant poll flags |
|
|
1384 | // could also call adns_processreadable etc. here |
|
|
1385 | struct pollfd *fd = (struct pollfd *)w->data; |
|
|
1386 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1387 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1388 | } |
1779 | } |
1389 | |
1780 | |
1390 | // create io watchers for each fd and a timer before blocking |
1781 | // create io watchers for each fd and a timer before blocking |
1391 | static void |
1782 | static void |
1392 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1783 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1393 | { |
1784 | { |
1394 | int timeout = 3600000;truct pollfd fds [nfd]; |
1785 | int timeout = 3600000; |
|
|
1786 | struct pollfd fds [nfd]; |
1395 | // actual code will need to loop here and realloc etc. |
1787 | // actual code will need to loop here and realloc etc. |
1396 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1788 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1397 | |
1789 | |
1398 | /* the callback is illegal, but won't be called as we stop during check */ |
1790 | /* the callback is illegal, but won't be called as we stop during check */ |
1399 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1791 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1400 | ev_timer_start (loop, &tw); |
1792 | ev_timer_start (loop, &tw); |
1401 | |
1793 | |
1402 | // create on ev_io per pollfd |
1794 | // create one ev_io per pollfd |
1403 | for (int i = 0; i < nfd; ++i) |
1795 | for (int i = 0; i < nfd; ++i) |
1404 | { |
1796 | { |
1405 | ev_io_init (iow + i, io_cb, fds [i].fd, |
1797 | ev_io_init (iow + i, io_cb, fds [i].fd, |
1406 | ((fds [i].events & POLLIN ? EV_READ : 0) |
1798 | ((fds [i].events & POLLIN ? EV_READ : 0) |
1407 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1799 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1408 | |
1800 | |
1409 | fds [i].revents = 0; |
1801 | fds [i].revents = 0; |
1410 | iow [i].data = fds + i; |
|
|
1411 | ev_io_start (loop, iow + i); |
1802 | ev_io_start (loop, iow + i); |
1412 | } |
1803 | } |
1413 | } |
1804 | } |
1414 | |
1805 | |
1415 | // stop all watchers after blocking |
1806 | // stop all watchers after blocking |
… | |
… | |
1417 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
1808 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
1418 | { |
1809 | { |
1419 | ev_timer_stop (loop, &tw); |
1810 | ev_timer_stop (loop, &tw); |
1420 | |
1811 | |
1421 | for (int i = 0; i < nfd; ++i) |
1812 | for (int i = 0; i < nfd; ++i) |
|
|
1813 | { |
|
|
1814 | // set the relevant poll flags |
|
|
1815 | // could also call adns_processreadable etc. here |
|
|
1816 | struct pollfd *fd = fds + i; |
|
|
1817 | int revents = ev_clear_pending (iow + i); |
|
|
1818 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1819 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1820 | |
|
|
1821 | // now stop the watcher |
1422 | ev_io_stop (loop, iow + i); |
1822 | ev_io_stop (loop, iow + i); |
|
|
1823 | } |
1423 | |
1824 | |
1424 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
1825 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
1826 | } |
|
|
1827 | |
|
|
1828 | Method 2: This would be just like method 1, but you run C<adns_afterpoll> |
|
|
1829 | in the prepare watcher and would dispose of the check watcher. |
|
|
1830 | |
|
|
1831 | Method 3: If the module to be embedded supports explicit event |
|
|
1832 | notification (adns does), you can also make use of the actual watcher |
|
|
1833 | callbacks, and only destroy/create the watchers in the prepare watcher. |
|
|
1834 | |
|
|
1835 | static void |
|
|
1836 | timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1837 | { |
|
|
1838 | adns_state ads = (adns_state)w->data; |
|
|
1839 | update_now (EV_A); |
|
|
1840 | |
|
|
1841 | adns_processtimeouts (ads, &tv_now); |
|
|
1842 | } |
|
|
1843 | |
|
|
1844 | static void |
|
|
1845 | io_cb (EV_P_ ev_io *w, int revents) |
|
|
1846 | { |
|
|
1847 | adns_state ads = (adns_state)w->data; |
|
|
1848 | update_now (EV_A); |
|
|
1849 | |
|
|
1850 | if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now); |
|
|
1851 | if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now); |
|
|
1852 | } |
|
|
1853 | |
|
|
1854 | // do not ever call adns_afterpoll |
|
|
1855 | |
|
|
1856 | Method 4: Do not use a prepare or check watcher because the module you |
|
|
1857 | want to embed is too inflexible to support it. Instead, youc na override |
|
|
1858 | their poll function. The drawback with this solution is that the main |
|
|
1859 | loop is now no longer controllable by EV. The C<Glib::EV> module does |
|
|
1860 | this. |
|
|
1861 | |
|
|
1862 | static gint |
|
|
1863 | event_poll_func (GPollFD *fds, guint nfds, gint timeout) |
|
|
1864 | { |
|
|
1865 | int got_events = 0; |
|
|
1866 | |
|
|
1867 | for (n = 0; n < nfds; ++n) |
|
|
1868 | // create/start io watcher that sets the relevant bits in fds[n] and increment got_events |
|
|
1869 | |
|
|
1870 | if (timeout >= 0) |
|
|
1871 | // create/start timer |
|
|
1872 | |
|
|
1873 | // poll |
|
|
1874 | ev_loop (EV_A_ 0); |
|
|
1875 | |
|
|
1876 | // stop timer again |
|
|
1877 | if (timeout >= 0) |
|
|
1878 | ev_timer_stop (EV_A_ &to); |
|
|
1879 | |
|
|
1880 | // stop io watchers again - their callbacks should have set |
|
|
1881 | for (n = 0; n < nfds; ++n) |
|
|
1882 | ev_io_stop (EV_A_ iow [n]); |
|
|
1883 | |
|
|
1884 | return got_events; |
1425 | } |
1885 | } |
1426 | |
1886 | |
1427 | |
1887 | |
1428 | =head2 C<ev_embed> - when one backend isn't enough... |
1888 | =head2 C<ev_embed> - when one backend isn't enough... |
1429 | |
1889 | |
… | |
… | |
1472 | portable one. |
1932 | portable one. |
1473 | |
1933 | |
1474 | So when you want to use this feature you will always have to be prepared |
1934 | So when you want to use this feature you will always have to be prepared |
1475 | that you cannot get an embeddable loop. The recommended way to get around |
1935 | that you cannot get an embeddable loop. The recommended way to get around |
1476 | this is to have a separate variables for your embeddable loop, try to |
1936 | this is to have a separate variables for your embeddable loop, try to |
1477 | create it, and if that fails, use the normal loop for everything: |
1937 | create it, and if that fails, use the normal loop for everything. |
|
|
1938 | |
|
|
1939 | =head3 Watcher-Specific Functions and Data Members |
|
|
1940 | |
|
|
1941 | =over 4 |
|
|
1942 | |
|
|
1943 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
1944 | |
|
|
1945 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
1946 | |
|
|
1947 | Configures the watcher to embed the given loop, which must be |
|
|
1948 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
|
|
1949 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
1950 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
1951 | if you do not want thta, you need to temporarily stop the embed watcher). |
|
|
1952 | |
|
|
1953 | =item ev_embed_sweep (loop, ev_embed *) |
|
|
1954 | |
|
|
1955 | Make a single, non-blocking sweep over the embedded loop. This works |
|
|
1956 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
|
|
1957 | apropriate way for embedded loops. |
|
|
1958 | |
|
|
1959 | =item struct ev_loop *other [read-only] |
|
|
1960 | |
|
|
1961 | The embedded event loop. |
|
|
1962 | |
|
|
1963 | =back |
|
|
1964 | |
|
|
1965 | =head3 Examples |
|
|
1966 | |
|
|
1967 | Example: Try to get an embeddable event loop and embed it into the default |
|
|
1968 | event loop. If that is not possible, use the default loop. The default |
|
|
1969 | loop is stored in C<loop_hi>, while the mebeddable loop is stored in |
|
|
1970 | C<loop_lo> (which is C<loop_hi> in the acse no embeddable loop can be |
|
|
1971 | used). |
1478 | |
1972 | |
1479 | struct ev_loop *loop_hi = ev_default_init (0); |
1973 | struct ev_loop *loop_hi = ev_default_init (0); |
1480 | struct ev_loop *loop_lo = 0; |
1974 | struct ev_loop *loop_lo = 0; |
1481 | struct ev_embed embed; |
1975 | struct ev_embed embed; |
1482 | |
1976 | |
… | |
… | |
1493 | ev_embed_start (loop_hi, &embed); |
1987 | ev_embed_start (loop_hi, &embed); |
1494 | } |
1988 | } |
1495 | else |
1989 | else |
1496 | loop_lo = loop_hi; |
1990 | loop_lo = loop_hi; |
1497 | |
1991 | |
1498 | =over 4 |
1992 | Example: Check if kqueue is available but not recommended and create |
|
|
1993 | a kqueue backend for use with sockets (which usually work with any |
|
|
1994 | kqueue implementation). Store the kqueue/socket-only event loop in |
|
|
1995 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
1499 | |
1996 | |
1500 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
1997 | struct ev_loop *loop = ev_default_init (0); |
|
|
1998 | struct ev_loop *loop_socket = 0; |
|
|
1999 | struct ev_embed embed; |
|
|
2000 | |
|
|
2001 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
|
|
2002 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
|
|
2003 | { |
|
|
2004 | ev_embed_init (&embed, 0, loop_socket); |
|
|
2005 | ev_embed_start (loop, &embed); |
|
|
2006 | } |
1501 | |
2007 | |
1502 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
2008 | if (!loop_socket) |
|
|
2009 | loop_socket = loop; |
1503 | |
2010 | |
1504 | Configures the watcher to embed the given loop, which must be |
2011 | // now use loop_socket for all sockets, and loop for everything else |
1505 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
|
|
1506 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
1507 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
1508 | if you do not want thta, you need to temporarily stop the embed watcher). |
|
|
1509 | |
|
|
1510 | =item ev_embed_sweep (loop, ev_embed *) |
|
|
1511 | |
|
|
1512 | Make a single, non-blocking sweep over the embedded loop. This works |
|
|
1513 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
|
|
1514 | apropriate way for embedded loops. |
|
|
1515 | |
|
|
1516 | =item struct ev_loop *loop [read-only] |
|
|
1517 | |
|
|
1518 | The embedded event loop. |
|
|
1519 | |
|
|
1520 | =back |
|
|
1521 | |
2012 | |
1522 | |
2013 | |
1523 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
2014 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
1524 | |
2015 | |
1525 | Fork watchers are called when a C<fork ()> was detected (usually because |
2016 | Fork watchers are called when a C<fork ()> was detected (usually because |
… | |
… | |
1528 | event loop blocks next and before C<ev_check> watchers are being called, |
2019 | event loop blocks next and before C<ev_check> watchers are being called, |
1529 | and only in the child after the fork. If whoever good citizen calling |
2020 | and only in the child after the fork. If whoever good citizen calling |
1530 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
2021 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
1531 | handlers will be invoked, too, of course. |
2022 | handlers will be invoked, too, of course. |
1532 | |
2023 | |
|
|
2024 | =head3 Watcher-Specific Functions and Data Members |
|
|
2025 | |
1533 | =over 4 |
2026 | =over 4 |
1534 | |
2027 | |
1535 | =item ev_fork_init (ev_signal *, callback) |
2028 | =item ev_fork_init (ev_signal *, callback) |
1536 | |
2029 | |
1537 | Initialises and configures the fork watcher - it has no parameters of any |
2030 | Initialises and configures the fork watcher - it has no parameters of any |
… | |
… | |
1633 | |
2126 | |
1634 | To use it, |
2127 | To use it, |
1635 | |
2128 | |
1636 | #include <ev++.h> |
2129 | #include <ev++.h> |
1637 | |
2130 | |
1638 | (it is not installed by default). This automatically includes F<ev.h> |
2131 | This automatically includes F<ev.h> and puts all of its definitions (many |
1639 | and puts all of its definitions (many of them macros) into the global |
2132 | of them macros) into the global namespace. All C++ specific things are |
1640 | namespace. All C++ specific things are put into the C<ev> namespace. |
2133 | put into the C<ev> namespace. It should support all the same embedding |
|
|
2134 | options as F<ev.h>, most notably C<EV_MULTIPLICITY>. |
1641 | |
2135 | |
1642 | It should support all the same embedding options as F<ev.h>, most notably |
2136 | Care has been taken to keep the overhead low. The only data member the C++ |
1643 | C<EV_MULTIPLICITY>. |
2137 | classes add (compared to plain C-style watchers) is the event loop pointer |
|
|
2138 | that the watcher is associated with (or no additional members at all if |
|
|
2139 | you disable C<EV_MULTIPLICITY> when embedding libev). |
|
|
2140 | |
|
|
2141 | Currently, functions, and static and non-static member functions can be |
|
|
2142 | used as callbacks. Other types should be easy to add as long as they only |
|
|
2143 | need one additional pointer for context. If you need support for other |
|
|
2144 | types of functors please contact the author (preferably after implementing |
|
|
2145 | it). |
1644 | |
2146 | |
1645 | Here is a list of things available in the C<ev> namespace: |
2147 | Here is a list of things available in the C<ev> namespace: |
1646 | |
2148 | |
1647 | =over 4 |
2149 | =over 4 |
1648 | |
2150 | |
… | |
… | |
1664 | |
2166 | |
1665 | All of those classes have these methods: |
2167 | All of those classes have these methods: |
1666 | |
2168 | |
1667 | =over 4 |
2169 | =over 4 |
1668 | |
2170 | |
1669 | =item ev::TYPE::TYPE (object *, object::method *) |
2171 | =item ev::TYPE::TYPE () |
1670 | |
2172 | |
1671 | =item ev::TYPE::TYPE (object *, object::method *, struct ev_loop *) |
2173 | =item ev::TYPE::TYPE (struct ev_loop *) |
1672 | |
2174 | |
1673 | =item ev::TYPE::~TYPE |
2175 | =item ev::TYPE::~TYPE |
1674 | |
2176 | |
1675 | The constructor takes a pointer to an object and a method pointer to |
2177 | The constructor (optionally) takes an event loop to associate the watcher |
1676 | the event handler callback to call in this class. The constructor calls |
2178 | with. If it is omitted, it will use C<EV_DEFAULT>. |
1677 | C<ev_init> for you, which means you have to call the C<set> method |
2179 | |
1678 | before starting it. If you do not specify a loop then the constructor |
2180 | The constructor calls C<ev_init> for you, which means you have to call the |
1679 | automatically associates the default loop with this watcher. |
2181 | C<set> method before starting it. |
|
|
2182 | |
|
|
2183 | It will not set a callback, however: You have to call the templated C<set> |
|
|
2184 | method to set a callback before you can start the watcher. |
|
|
2185 | |
|
|
2186 | (The reason why you have to use a method is a limitation in C++ which does |
|
|
2187 | not allow explicit template arguments for constructors). |
1680 | |
2188 | |
1681 | The destructor automatically stops the watcher if it is active. |
2189 | The destructor automatically stops the watcher if it is active. |
|
|
2190 | |
|
|
2191 | =item w->set<class, &class::method> (object *) |
|
|
2192 | |
|
|
2193 | This method sets the callback method to call. The method has to have a |
|
|
2194 | signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as |
|
|
2195 | first argument and the C<revents> as second. The object must be given as |
|
|
2196 | parameter and is stored in the C<data> member of the watcher. |
|
|
2197 | |
|
|
2198 | This method synthesizes efficient thunking code to call your method from |
|
|
2199 | the C callback that libev requires. If your compiler can inline your |
|
|
2200 | callback (i.e. it is visible to it at the place of the C<set> call and |
|
|
2201 | your compiler is good :), then the method will be fully inlined into the |
|
|
2202 | thunking function, making it as fast as a direct C callback. |
|
|
2203 | |
|
|
2204 | Example: simple class declaration and watcher initialisation |
|
|
2205 | |
|
|
2206 | struct myclass |
|
|
2207 | { |
|
|
2208 | void io_cb (ev::io &w, int revents) { } |
|
|
2209 | } |
|
|
2210 | |
|
|
2211 | myclass obj; |
|
|
2212 | ev::io iow; |
|
|
2213 | iow.set <myclass, &myclass::io_cb> (&obj); |
|
|
2214 | |
|
|
2215 | =item w->set<function> (void *data = 0) |
|
|
2216 | |
|
|
2217 | Also sets a callback, but uses a static method or plain function as |
|
|
2218 | callback. The optional C<data> argument will be stored in the watcher's |
|
|
2219 | C<data> member and is free for you to use. |
|
|
2220 | |
|
|
2221 | The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>. |
|
|
2222 | |
|
|
2223 | See the method-C<set> above for more details. |
|
|
2224 | |
|
|
2225 | Example: |
|
|
2226 | |
|
|
2227 | static void io_cb (ev::io &w, int revents) { } |
|
|
2228 | iow.set <io_cb> (); |
1682 | |
2229 | |
1683 | =item w->set (struct ev_loop *) |
2230 | =item w->set (struct ev_loop *) |
1684 | |
2231 | |
1685 | Associates a different C<struct ev_loop> with this watcher. You can only |
2232 | Associates a different C<struct ev_loop> with this watcher. You can only |
1686 | do this when the watcher is inactive (and not pending either). |
2233 | do this when the watcher is inactive (and not pending either). |
1687 | |
2234 | |
1688 | =item w->set ([args]) |
2235 | =item w->set ([args]) |
1689 | |
2236 | |
1690 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
2237 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
1691 | called at least once. Unlike the C counterpart, an active watcher gets |
2238 | called at least once. Unlike the C counterpart, an active watcher gets |
1692 | automatically stopped and restarted. |
2239 | automatically stopped and restarted when reconfiguring it with this |
|
|
2240 | method. |
1693 | |
2241 | |
1694 | =item w->start () |
2242 | =item w->start () |
1695 | |
2243 | |
1696 | Starts the watcher. Note that there is no C<loop> argument as the |
2244 | Starts the watcher. Note that there is no C<loop> argument, as the |
1697 | constructor already takes the loop. |
2245 | constructor already stores the event loop. |
1698 | |
2246 | |
1699 | =item w->stop () |
2247 | =item w->stop () |
1700 | |
2248 | |
1701 | Stops the watcher if it is active. Again, no C<loop> argument. |
2249 | Stops the watcher if it is active. Again, no C<loop> argument. |
1702 | |
2250 | |
1703 | =item w->again () C<ev::timer>, C<ev::periodic> only |
2251 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
1704 | |
2252 | |
1705 | For C<ev::timer> and C<ev::periodic>, this invokes the corresponding |
2253 | For C<ev::timer> and C<ev::periodic>, this invokes the corresponding |
1706 | C<ev_TYPE_again> function. |
2254 | C<ev_TYPE_again> function. |
1707 | |
2255 | |
1708 | =item w->sweep () C<ev::embed> only |
2256 | =item w->sweep () (C<ev::embed> only) |
1709 | |
2257 | |
1710 | Invokes C<ev_embed_sweep>. |
2258 | Invokes C<ev_embed_sweep>. |
1711 | |
2259 | |
1712 | =item w->update () C<ev::stat> only |
2260 | =item w->update () (C<ev::stat> only) |
1713 | |
2261 | |
1714 | Invokes C<ev_stat_stat>. |
2262 | Invokes C<ev_stat_stat>. |
1715 | |
2263 | |
1716 | =back |
2264 | =back |
1717 | |
2265 | |
… | |
… | |
1727 | |
2275 | |
1728 | myclass (); |
2276 | myclass (); |
1729 | } |
2277 | } |
1730 | |
2278 | |
1731 | myclass::myclass (int fd) |
2279 | myclass::myclass (int fd) |
1732 | : io (this, &myclass::io_cb), |
|
|
1733 | idle (this, &myclass::idle_cb) |
|
|
1734 | { |
2280 | { |
|
|
2281 | io .set <myclass, &myclass::io_cb > (this); |
|
|
2282 | idle.set <myclass, &myclass::idle_cb> (this); |
|
|
2283 | |
1735 | io.start (fd, ev::READ); |
2284 | io.start (fd, ev::READ); |
1736 | } |
2285 | } |
1737 | |
2286 | |
1738 | |
2287 | |
1739 | =head1 MACRO MAGIC |
2288 | =head1 MACRO MAGIC |
1740 | |
2289 | |
1741 | Libev can be compiled with a variety of options, the most fundemantal is |
2290 | Libev can be compiled with a variety of options, the most fundamantal |
1742 | C<EV_MULTIPLICITY>. This option determines wether (most) functions and |
2291 | of which is C<EV_MULTIPLICITY>. This option determines whether (most) |
1743 | callbacks have an initial C<struct ev_loop *> argument. |
2292 | functions and callbacks have an initial C<struct ev_loop *> argument. |
1744 | |
2293 | |
1745 | To make it easier to write programs that cope with either variant, the |
2294 | To make it easier to write programs that cope with either variant, the |
1746 | following macros are defined: |
2295 | following macros are defined: |
1747 | |
2296 | |
1748 | =over 4 |
2297 | =over 4 |
… | |
… | |
1780 | Similar to the other two macros, this gives you the value of the default |
2329 | Similar to the other two macros, this gives you the value of the default |
1781 | loop, if multiple loops are supported ("ev loop default"). |
2330 | loop, if multiple loops are supported ("ev loop default"). |
1782 | |
2331 | |
1783 | =back |
2332 | =back |
1784 | |
2333 | |
1785 | Example: Declare and initialise a check watcher, working regardless of |
2334 | Example: Declare and initialise a check watcher, utilising the above |
1786 | wether multiple loops are supported or not. |
2335 | macros so it will work regardless of whether multiple loops are supported |
|
|
2336 | or not. |
1787 | |
2337 | |
1788 | static void |
2338 | static void |
1789 | check_cb (EV_P_ ev_timer *w, int revents) |
2339 | check_cb (EV_P_ ev_timer *w, int revents) |
1790 | { |
2340 | { |
1791 | ev_check_stop (EV_A_ w); |
2341 | ev_check_stop (EV_A_ w); |
… | |
… | |
1794 | ev_check check; |
2344 | ev_check check; |
1795 | ev_check_init (&check, check_cb); |
2345 | ev_check_init (&check, check_cb); |
1796 | ev_check_start (EV_DEFAULT_ &check); |
2346 | ev_check_start (EV_DEFAULT_ &check); |
1797 | ev_loop (EV_DEFAULT_ 0); |
2347 | ev_loop (EV_DEFAULT_ 0); |
1798 | |
2348 | |
1799 | |
|
|
1800 | =head1 EMBEDDING |
2349 | =head1 EMBEDDING |
1801 | |
2350 | |
1802 | Libev can (and often is) directly embedded into host |
2351 | Libev can (and often is) directly embedded into host |
1803 | applications. Examples of applications that embed it include the Deliantra |
2352 | applications. Examples of applications that embed it include the Deliantra |
1804 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
2353 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
1805 | and rxvt-unicode. |
2354 | and rxvt-unicode. |
1806 | |
2355 | |
1807 | The goal is to enable you to just copy the neecssary files into your |
2356 | The goal is to enable you to just copy the necessary files into your |
1808 | source directory without having to change even a single line in them, so |
2357 | source directory without having to change even a single line in them, so |
1809 | you can easily upgrade by simply copying (or having a checked-out copy of |
2358 | you can easily upgrade by simply copying (or having a checked-out copy of |
1810 | libev somewhere in your source tree). |
2359 | libev somewhere in your source tree). |
1811 | |
2360 | |
1812 | =head2 FILESETS |
2361 | =head2 FILESETS |
… | |
… | |
1843 | ev_vars.h |
2392 | ev_vars.h |
1844 | ev_wrap.h |
2393 | ev_wrap.h |
1845 | |
2394 | |
1846 | ev_win32.c required on win32 platforms only |
2395 | ev_win32.c required on win32 platforms only |
1847 | |
2396 | |
1848 | ev_select.c only when select backend is enabled (which is by default) |
2397 | ev_select.c only when select backend is enabled (which is enabled by default) |
1849 | ev_poll.c only when poll backend is enabled (disabled by default) |
2398 | ev_poll.c only when poll backend is enabled (disabled by default) |
1850 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
2399 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
1851 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
2400 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
1852 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
2401 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
1853 | |
2402 | |
… | |
… | |
1902 | |
2451 | |
1903 | If defined to be C<1>, libev will try to detect the availability of the |
2452 | If defined to be C<1>, libev will try to detect the availability of the |
1904 | monotonic clock option at both compiletime and runtime. Otherwise no use |
2453 | monotonic clock option at both compiletime and runtime. Otherwise no use |
1905 | of the monotonic clock option will be attempted. If you enable this, you |
2454 | of the monotonic clock option will be attempted. If you enable this, you |
1906 | usually have to link against librt or something similar. Enabling it when |
2455 | usually have to link against librt or something similar. Enabling it when |
1907 | the functionality isn't available is safe, though, althoguh you have |
2456 | the functionality isn't available is safe, though, although you have |
1908 | to make sure you link against any libraries where the C<clock_gettime> |
2457 | to make sure you link against any libraries where the C<clock_gettime> |
1909 | function is hiding in (often F<-lrt>). |
2458 | function is hiding in (often F<-lrt>). |
1910 | |
2459 | |
1911 | =item EV_USE_REALTIME |
2460 | =item EV_USE_REALTIME |
1912 | |
2461 | |
1913 | If defined to be C<1>, libev will try to detect the availability of the |
2462 | If defined to be C<1>, libev will try to detect the availability of the |
1914 | realtime clock option at compiletime (and assume its availability at |
2463 | realtime clock option at compiletime (and assume its availability at |
1915 | runtime if successful). Otherwise no use of the realtime clock option will |
2464 | runtime if successful). Otherwise no use of the realtime clock option will |
1916 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
2465 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
1917 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries |
2466 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See the |
1918 | in the description of C<EV_USE_MONOTONIC>, though. |
2467 | note about libraries in the description of C<EV_USE_MONOTONIC>, though. |
|
|
2468 | |
|
|
2469 | =item EV_USE_NANOSLEEP |
|
|
2470 | |
|
|
2471 | If defined to be C<1>, libev will assume that C<nanosleep ()> is available |
|
|
2472 | and will use it for delays. Otherwise it will use C<select ()>. |
1919 | |
2473 | |
1920 | =item EV_USE_SELECT |
2474 | =item EV_USE_SELECT |
1921 | |
2475 | |
1922 | If undefined or defined to be C<1>, libev will compile in support for the |
2476 | If undefined or defined to be C<1>, libev will compile in support for the |
1923 | C<select>(2) backend. No attempt at autodetection will be done: if no |
2477 | C<select>(2) backend. No attempt at autodetection will be done: if no |
… | |
… | |
1941 | wants osf handles on win32 (this is the case when the select to |
2495 | wants osf handles on win32 (this is the case when the select to |
1942 | be used is the winsock select). This means that it will call |
2496 | be used is the winsock select). This means that it will call |
1943 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
2497 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
1944 | it is assumed that all these functions actually work on fds, even |
2498 | it is assumed that all these functions actually work on fds, even |
1945 | on win32. Should not be defined on non-win32 platforms. |
2499 | on win32. Should not be defined on non-win32 platforms. |
|
|
2500 | |
|
|
2501 | =item EV_FD_TO_WIN32_HANDLE |
|
|
2502 | |
|
|
2503 | If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map |
|
|
2504 | file descriptors to socket handles. When not defining this symbol (the |
|
|
2505 | default), then libev will call C<_get_osfhandle>, which is usually |
|
|
2506 | correct. In some cases, programs use their own file descriptor management, |
|
|
2507 | in which case they can provide this function to map fds to socket handles. |
1946 | |
2508 | |
1947 | =item EV_USE_POLL |
2509 | =item EV_USE_POLL |
1948 | |
2510 | |
1949 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
2511 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
1950 | backend. Otherwise it will be enabled on non-win32 platforms. It |
2512 | backend. Otherwise it will be enabled on non-win32 platforms. It |
… | |
… | |
1978 | |
2540 | |
1979 | =item EV_USE_DEVPOLL |
2541 | =item EV_USE_DEVPOLL |
1980 | |
2542 | |
1981 | reserved for future expansion, works like the USE symbols above. |
2543 | reserved for future expansion, works like the USE symbols above. |
1982 | |
2544 | |
|
|
2545 | =item EV_USE_INOTIFY |
|
|
2546 | |
|
|
2547 | If defined to be C<1>, libev will compile in support for the Linux inotify |
|
|
2548 | interface to speed up C<ev_stat> watchers. Its actual availability will |
|
|
2549 | be detected at runtime. |
|
|
2550 | |
1983 | =item EV_H |
2551 | =item EV_H |
1984 | |
2552 | |
1985 | The name of the F<ev.h> header file used to include it. The default if |
2553 | The name of the F<ev.h> header file used to include it. The default if |
1986 | undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This |
2554 | undefined is C<"ev.h"> in F<event.h> and F<ev.c>. This can be used to |
1987 | can be used to virtually rename the F<ev.h> header file in case of conflicts. |
2555 | virtually rename the F<ev.h> header file in case of conflicts. |
1988 | |
2556 | |
1989 | =item EV_CONFIG_H |
2557 | =item EV_CONFIG_H |
1990 | |
2558 | |
1991 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
2559 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
1992 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
2560 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
1993 | C<EV_H>, above. |
2561 | C<EV_H>, above. |
1994 | |
2562 | |
1995 | =item EV_EVENT_H |
2563 | =item EV_EVENT_H |
1996 | |
2564 | |
1997 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
2565 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
1998 | of how the F<event.h> header can be found. |
2566 | of how the F<event.h> header can be found, the dfeault is C<"event.h">. |
1999 | |
2567 | |
2000 | =item EV_PROTOTYPES |
2568 | =item EV_PROTOTYPES |
2001 | |
2569 | |
2002 | If defined to be C<0>, then F<ev.h> will not define any function |
2570 | If defined to be C<0>, then F<ev.h> will not define any function |
2003 | prototypes, but still define all the structs and other symbols. This is |
2571 | prototypes, but still define all the structs and other symbols. This is |
… | |
… | |
2010 | will have the C<struct ev_loop *> as first argument, and you can create |
2578 | will have the C<struct ev_loop *> as first argument, and you can create |
2011 | additional independent event loops. Otherwise there will be no support |
2579 | additional independent event loops. Otherwise there will be no support |
2012 | for multiple event loops and there is no first event loop pointer |
2580 | for multiple event loops and there is no first event loop pointer |
2013 | argument. Instead, all functions act on the single default loop. |
2581 | argument. Instead, all functions act on the single default loop. |
2014 | |
2582 | |
|
|
2583 | =item EV_MINPRI |
|
|
2584 | |
|
|
2585 | =item EV_MAXPRI |
|
|
2586 | |
|
|
2587 | The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to |
|
|
2588 | C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can |
|
|
2589 | provide for more priorities by overriding those symbols (usually defined |
|
|
2590 | to be C<-2> and C<2>, respectively). |
|
|
2591 | |
|
|
2592 | When doing priority-based operations, libev usually has to linearly search |
|
|
2593 | all the priorities, so having many of them (hundreds) uses a lot of space |
|
|
2594 | and time, so using the defaults of five priorities (-2 .. +2) is usually |
|
|
2595 | fine. |
|
|
2596 | |
|
|
2597 | If your embedding app does not need any priorities, defining these both to |
|
|
2598 | C<0> will save some memory and cpu. |
|
|
2599 | |
2015 | =item EV_PERIODIC_ENABLE |
2600 | =item EV_PERIODIC_ENABLE |
2016 | |
2601 | |
2017 | If undefined or defined to be C<1>, then periodic timers are supported. If |
2602 | If undefined or defined to be C<1>, then periodic timers are supported. If |
2018 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
2603 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
2019 | code. |
2604 | code. |
2020 | |
2605 | |
|
|
2606 | =item EV_IDLE_ENABLE |
|
|
2607 | |
|
|
2608 | If undefined or defined to be C<1>, then idle watchers are supported. If |
|
|
2609 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
2610 | code. |
|
|
2611 | |
2021 | =item EV_EMBED_ENABLE |
2612 | =item EV_EMBED_ENABLE |
2022 | |
2613 | |
2023 | If undefined or defined to be C<1>, then embed watchers are supported. If |
2614 | If undefined or defined to be C<1>, then embed watchers are supported. If |
2024 | defined to be C<0>, then they are not. |
2615 | defined to be C<0>, then they are not. |
2025 | |
2616 | |
… | |
… | |
2042 | =item EV_PID_HASHSIZE |
2633 | =item EV_PID_HASHSIZE |
2043 | |
2634 | |
2044 | C<ev_child> watchers use a small hash table to distribute workload by |
2635 | C<ev_child> watchers use a small hash table to distribute workload by |
2045 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
2636 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
2046 | than enough. If you need to manage thousands of children you might want to |
2637 | than enough. If you need to manage thousands of children you might want to |
2047 | increase this value. |
2638 | increase this value (I<must> be a power of two). |
|
|
2639 | |
|
|
2640 | =item EV_INOTIFY_HASHSIZE |
|
|
2641 | |
|
|
2642 | C<ev_stat> watchers use a small hash table to distribute workload by |
|
|
2643 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
|
|
2644 | usually more than enough. If you need to manage thousands of C<ev_stat> |
|
|
2645 | watchers you might want to increase this value (I<must> be a power of |
|
|
2646 | two). |
2048 | |
2647 | |
2049 | =item EV_COMMON |
2648 | =item EV_COMMON |
2050 | |
2649 | |
2051 | By default, all watchers have a C<void *data> member. By redefining |
2650 | By default, all watchers have a C<void *data> member. By redefining |
2052 | this macro to a something else you can include more and other types of |
2651 | this macro to a something else you can include more and other types of |
… | |
… | |
2065 | |
2664 | |
2066 | =item ev_set_cb (ev, cb) |
2665 | =item ev_set_cb (ev, cb) |
2067 | |
2666 | |
2068 | Can be used to change the callback member declaration in each watcher, |
2667 | Can be used to change the callback member declaration in each watcher, |
2069 | and the way callbacks are invoked and set. Must expand to a struct member |
2668 | and the way callbacks are invoked and set. Must expand to a struct member |
2070 | definition and a statement, respectively. See the F<ev.v> header file for |
2669 | definition and a statement, respectively. See the F<ev.h> header file for |
2071 | their default definitions. One possible use for overriding these is to |
2670 | their default definitions. One possible use for overriding these is to |
2072 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
2671 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
2073 | method calls instead of plain function calls in C++. |
2672 | method calls instead of plain function calls in C++. |
|
|
2673 | |
|
|
2674 | =head2 EXPORTED API SYMBOLS |
|
|
2675 | |
|
|
2676 | If you need to re-export the API (e.g. via a dll) and you need a list of |
|
|
2677 | exported symbols, you can use the provided F<Symbol.*> files which list |
|
|
2678 | all public symbols, one per line: |
|
|
2679 | |
|
|
2680 | Symbols.ev for libev proper |
|
|
2681 | Symbols.event for the libevent emulation |
|
|
2682 | |
|
|
2683 | This can also be used to rename all public symbols to avoid clashes with |
|
|
2684 | multiple versions of libev linked together (which is obviously bad in |
|
|
2685 | itself, but sometimes it is inconvinient to avoid this). |
|
|
2686 | |
|
|
2687 | A sed command like this will create wrapper C<#define>'s that you need to |
|
|
2688 | include before including F<ev.h>: |
|
|
2689 | |
|
|
2690 | <Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h |
|
|
2691 | |
|
|
2692 | This would create a file F<wrap.h> which essentially looks like this: |
|
|
2693 | |
|
|
2694 | #define ev_backend myprefix_ev_backend |
|
|
2695 | #define ev_check_start myprefix_ev_check_start |
|
|
2696 | #define ev_check_stop myprefix_ev_check_stop |
|
|
2697 | ... |
2074 | |
2698 | |
2075 | =head2 EXAMPLES |
2699 | =head2 EXAMPLES |
2076 | |
2700 | |
2077 | For a real-world example of a program the includes libev |
2701 | For a real-world example of a program the includes libev |
2078 | verbatim, you can have a look at the EV perl module |
2702 | verbatim, you can have a look at the EV perl module |
… | |
… | |
2081 | interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file |
2705 | interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file |
2082 | will be compiled. It is pretty complex because it provides its own header |
2706 | will be compiled. It is pretty complex because it provides its own header |
2083 | file. |
2707 | file. |
2084 | |
2708 | |
2085 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
2709 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
2086 | that everybody includes and which overrides some autoconf choices: |
2710 | that everybody includes and which overrides some configure choices: |
2087 | |
2711 | |
|
|
2712 | #define EV_MINIMAL 1 |
2088 | #define EV_USE_POLL 0 |
2713 | #define EV_USE_POLL 0 |
2089 | #define EV_MULTIPLICITY 0 |
2714 | #define EV_MULTIPLICITY 0 |
2090 | #define EV_PERIODICS 0 |
2715 | #define EV_PERIODIC_ENABLE 0 |
|
|
2716 | #define EV_STAT_ENABLE 0 |
|
|
2717 | #define EV_FORK_ENABLE 0 |
2091 | #define EV_CONFIG_H <config.h> |
2718 | #define EV_CONFIG_H <config.h> |
|
|
2719 | #define EV_MINPRI 0 |
|
|
2720 | #define EV_MAXPRI 0 |
2092 | |
2721 | |
2093 | #include "ev++.h" |
2722 | #include "ev++.h" |
2094 | |
2723 | |
2095 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
2724 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
2096 | |
2725 | |
… | |
… | |
2102 | |
2731 | |
2103 | In this section the complexities of (many of) the algorithms used inside |
2732 | In this section the complexities of (many of) the algorithms used inside |
2104 | libev will be explained. For complexity discussions about backends see the |
2733 | libev will be explained. For complexity discussions about backends see the |
2105 | documentation for C<ev_default_init>. |
2734 | documentation for C<ev_default_init>. |
2106 | |
2735 | |
|
|
2736 | All of the following are about amortised time: If an array needs to be |
|
|
2737 | extended, libev needs to realloc and move the whole array, but this |
|
|
2738 | happens asymptotically never with higher number of elements, so O(1) might |
|
|
2739 | mean it might do a lengthy realloc operation in rare cases, but on average |
|
|
2740 | it is much faster and asymptotically approaches constant time. |
|
|
2741 | |
2107 | =over 4 |
2742 | =over 4 |
2108 | |
2743 | |
2109 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2744 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2110 | |
2745 | |
|
|
2746 | This means that, when you have a watcher that triggers in one hour and |
|
|
2747 | there are 100 watchers that would trigger before that then inserting will |
|
|
2748 | have to skip roughly seven (C<ld 100>) of these watchers. |
|
|
2749 | |
2111 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
2750 | =item Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers) |
|
|
2751 | |
|
|
2752 | That means that changing a timer costs less than removing/adding them |
|
|
2753 | as only the relative motion in the event queue has to be paid for. |
2112 | |
2754 | |
2113 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2755 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2114 | |
2756 | |
|
|
2757 | These just add the watcher into an array or at the head of a list. |
|
|
2758 | |
2115 | =item Stopping check/prepare/idle watchers: O(1) |
2759 | =item Stopping check/prepare/idle watchers: O(1) |
2116 | |
2760 | |
2117 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16)) |
2761 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2118 | |
2762 | |
|
|
2763 | These watchers are stored in lists then need to be walked to find the |
|
|
2764 | correct watcher to remove. The lists are usually short (you don't usually |
|
|
2765 | have many watchers waiting for the same fd or signal). |
|
|
2766 | |
2119 | =item Finding the next timer per loop iteration: O(1) |
2767 | =item Finding the next timer in each loop iteration: O(1) |
|
|
2768 | |
|
|
2769 | By virtue of using a binary heap, the next timer is always found at the |
|
|
2770 | beginning of the storage array. |
2120 | |
2771 | |
2121 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2772 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2122 | |
2773 | |
2123 | =item Activating one watcher: O(1) |
2774 | A change means an I/O watcher gets started or stopped, which requires |
|
|
2775 | libev to recalculate its status (and possibly tell the kernel, depending |
|
|
2776 | on backend and wether C<ev_io_set> was used). |
|
|
2777 | |
|
|
2778 | =item Activating one watcher (putting it into the pending state): O(1) |
|
|
2779 | |
|
|
2780 | =item Priority handling: O(number_of_priorities) |
|
|
2781 | |
|
|
2782 | Priorities are implemented by allocating some space for each |
|
|
2783 | priority. When doing priority-based operations, libev usually has to |
|
|
2784 | linearly search all the priorities, but starting/stopping and activating |
|
|
2785 | watchers becomes O(1) w.r.t. prioritiy handling. |
2124 | |
2786 | |
2125 | =back |
2787 | =back |
2126 | |
2788 | |
2127 | |
2789 | |
|
|
2790 | =head1 Win32 platform limitations and workarounds |
|
|
2791 | |
|
|
2792 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
|
|
2793 | requires, and its I/O model is fundamentally incompatible with the POSIX |
|
|
2794 | model. Libev still offers limited functionality on this platform in |
|
|
2795 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
|
|
2796 | descriptors. This only applies when using Win32 natively, not when using |
|
|
2797 | e.g. cygwin. |
|
|
2798 | |
|
|
2799 | There is no supported compilation method available on windows except |
|
|
2800 | embedding it into other applications. |
|
|
2801 | |
|
|
2802 | Due to the many, low, and arbitrary limits on the win32 platform and the |
|
|
2803 | abysmal performance of winsockets, using a large number of sockets is not |
|
|
2804 | recommended (and not reasonable). If your program needs to use more than |
|
|
2805 | a hundred or so sockets, then likely it needs to use a totally different |
|
|
2806 | implementation for windows, as libev offers the POSIX model, which cannot |
|
|
2807 | be implemented efficiently on windows (microsoft monopoly games). |
|
|
2808 | |
|
|
2809 | =over 4 |
|
|
2810 | |
|
|
2811 | =item The winsocket select function |
|
|
2812 | |
|
|
2813 | The winsocket C<select> function doesn't follow POSIX in that it requires |
|
|
2814 | socket I<handles> and not socket I<file descriptors>. This makes select |
|
|
2815 | very inefficient, and also requires a mapping from file descriptors |
|
|
2816 | to socket handles. See the discussion of the C<EV_SELECT_USE_FD_SET>, |
|
|
2817 | C<EV_SELECT_IS_WINSOCKET> and C<EV_FD_TO_WIN32_HANDLE> preprocessor |
|
|
2818 | symbols for more info. |
|
|
2819 | |
|
|
2820 | The configuration for a "naked" win32 using the microsoft runtime |
|
|
2821 | libraries and raw winsocket select is: |
|
|
2822 | |
|
|
2823 | #define EV_USE_SELECT 1 |
|
|
2824 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
|
|
2825 | |
|
|
2826 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
|
|
2827 | complexity in the O(n²) range when using win32. |
|
|
2828 | |
|
|
2829 | =item Limited number of file descriptors |
|
|
2830 | |
|
|
2831 | Windows has numerous arbitrary (and low) limits on things. Early versions |
|
|
2832 | of winsocket's select only supported waiting for a max. of C<64> handles |
|
|
2833 | (probably owning to the fact that all windows kernels can only wait for |
|
|
2834 | C<64> things at the same time internally; microsoft recommends spawning a |
|
|
2835 | chain of threads and wait for 63 handles and the previous thread in each). |
|
|
2836 | |
|
|
2837 | Newer versions support more handles, but you need to define C<FD_SETSIZE> |
|
|
2838 | to some high number (e.g. C<2048>) before compiling the winsocket select |
|
|
2839 | call (which might be in libev or elsewhere, for example, perl does its own |
|
|
2840 | select emulation on windows). |
|
|
2841 | |
|
|
2842 | Another limit is the number of file descriptors in the microsoft runtime |
|
|
2843 | libraries, which by default is C<64> (there must be a hidden I<64> fetish |
|
|
2844 | or something like this inside microsoft). You can increase this by calling |
|
|
2845 | C<_setmaxstdio>, which can increase this limit to C<2048> (another |
|
|
2846 | arbitrary limit), but is broken in many versions of the microsoft runtime |
|
|
2847 | libraries. |
|
|
2848 | |
|
|
2849 | This might get you to about C<512> or C<2048> sockets (depending on |
|
|
2850 | windows version and/or the phase of the moon). To get more, you need to |
|
|
2851 | wrap all I/O functions and provide your own fd management, but the cost of |
|
|
2852 | calling select (O(n²)) will likely make this unworkable. |
|
|
2853 | |
|
|
2854 | =back |
|
|
2855 | |
|
|
2856 | |
2128 | =head1 AUTHOR |
2857 | =head1 AUTHOR |
2129 | |
2858 | |
2130 | Marc Lehmann <libev@schmorp.de>. |
2859 | Marc Lehmann <libev@schmorp.de>. |
2131 | |
2860 | |