… | |
… | |
4 | |
4 | |
5 | =head1 SYNOPSIS |
5 | =head1 SYNOPSIS |
6 | |
6 | |
7 | #include <ev.h> |
7 | #include <ev.h> |
8 | |
8 | |
|
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9 | =head1 EXAMPLE PROGRAM |
|
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10 | |
|
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11 | #include <ev.h> |
|
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12 | |
|
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13 | ev_io stdin_watcher; |
|
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14 | ev_timer timeout_watcher; |
|
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15 | |
|
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16 | /* called when data readable on stdin */ |
|
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17 | static void |
|
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18 | stdin_cb (EV_P_ struct ev_io *w, int revents) |
|
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19 | { |
|
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20 | /* puts ("stdin ready"); */ |
|
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21 | ev_io_stop (EV_A_ w); /* just a syntax example */ |
|
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22 | ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */ |
|
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23 | } |
|
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24 | |
|
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25 | static void |
|
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26 | timeout_cb (EV_P_ struct ev_timer *w, int revents) |
|
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27 | { |
|
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28 | /* puts ("timeout"); */ |
|
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29 | ev_unloop (EV_A_ EVUNLOOP_ONE); /* leave one loop call */ |
|
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30 | } |
|
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31 | |
|
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32 | int |
|
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33 | main (void) |
|
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34 | { |
|
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35 | struct ev_loop *loop = ev_default_loop (0); |
|
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36 | |
|
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37 | /* initialise an io watcher, then start it */ |
|
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38 | ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
|
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39 | ev_io_start (loop, &stdin_watcher); |
|
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40 | |
|
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41 | /* simple non-repeating 5.5 second timeout */ |
|
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42 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
|
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43 | ev_timer_start (loop, &timeout_watcher); |
|
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44 | |
|
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45 | /* loop till timeout or data ready */ |
|
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46 | ev_loop (loop, 0); |
|
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47 | |
|
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48 | return 0; |
|
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49 | } |
|
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50 | |
9 | =head1 DESCRIPTION |
51 | =head1 DESCRIPTION |
10 | |
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 | |
11 | 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 |
12 | 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 |
13 | these event sources and provide your program with events. |
59 | these event sources and provide your program with events. |
14 | |
60 | |
15 | 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 |
16 | (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 |
17 | communicate events via a callback mechanism. |
63 | communicate events via a callback mechanism. |
… | |
… | |
21 | 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 |
22 | watcher. |
68 | watcher. |
23 | |
69 | |
24 | =head1 FEATURES |
70 | =head1 FEATURES |
25 | |
71 | |
26 | 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 |
27 | kqueue mechanisms for file descriptor events, relative timers, absolute |
73 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
28 | timers with customised rescheduling, signal events, process status change |
74 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
29 | events (related to SIGCHLD), and event watchers dealing with the event |
75 | (for C<ev_stat>), relative timers (C<ev_timer>), absolute timers |
30 | 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 | |
|
|
83 | It also is quite fast (see this |
31 | 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 |
32 | it to libevent for example). |
85 | for example). |
33 | |
86 | |
34 | =head1 CONVENTIONS |
87 | =head1 CONVENTIONS |
35 | |
88 | |
36 | Libev is very configurable. In this manual the default configuration |
89 | Libev is very configurable. In this manual the default configuration will |
37 | will be described, which supports multiple event loops. For more info |
90 | be described, which supports multiple event loops. For more info about |
38 | about various configuration options please have a look at the file |
91 | various configuration options please have a look at B<EMBED> section in |
39 | F<README.embed> in the libev distribution. If libev was configured without |
92 | this manual. If libev was configured without support for multiple event |
40 | support for multiple event loops, then all functions taking an initial |
93 | loops, then all functions taking an initial argument of name C<loop> |
41 | 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. |
42 | will not have this argument. |
|
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43 | |
95 | |
44 | =head1 TIME REPRESENTATION |
96 | =head1 TIME REPRESENTATION |
45 | |
97 | |
46 | Libev represents time as a single floating point number, representing the |
98 | Libev represents time as a single floating point number, representing the |
47 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
99 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
48 | 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 |
49 | 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 |
50 | 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 |
51 | it, you should treat it as such. |
103 | it, you should treat it as some floatingpoint value. Unlike the name |
52 | |
104 | component C<stamp> might indicate, it is also used for time differences |
|
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105 | throughout libev. |
53 | |
106 | |
54 | =head1 GLOBAL FUNCTIONS |
107 | =head1 GLOBAL FUNCTIONS |
55 | |
108 | |
56 | These functions can be called anytime, even before initialising the |
109 | These functions can be called anytime, even before initialising the |
57 | library in any way. |
110 | library in any way. |
… | |
… | |
66 | |
119 | |
67 | =item int ev_version_major () |
120 | =item int ev_version_major () |
68 | |
121 | |
69 | =item int ev_version_minor () |
122 | =item int ev_version_minor () |
70 | |
123 | |
71 | You can find out the major and minor version numbers of the library |
124 | You can find out the major and minor ABI version numbers of the library |
72 | you linked against by calling the functions C<ev_version_major> and |
125 | you linked against by calling the functions C<ev_version_major> and |
73 | C<ev_version_minor>. If you want, you can compare against the global |
126 | C<ev_version_minor>. If you want, you can compare against the global |
74 | symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the |
127 | symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the |
75 | version of the library your program was compiled against. |
128 | version of the library your program was compiled against. |
76 | |
129 | |
|
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130 | These version numbers refer to the ABI version of the library, not the |
|
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131 | release version. |
|
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132 | |
77 | Usually, it's a good idea to terminate if the major versions mismatch, |
133 | Usually, it's a good idea to terminate if the major versions mismatch, |
78 | as this indicates an incompatible change. Minor versions are usually |
134 | as this indicates an incompatible change. Minor versions are usually |
79 | compatible to older versions, so a larger minor version alone is usually |
135 | compatible to older versions, so a larger minor version alone is usually |
80 | not a problem. |
136 | not a problem. |
81 | |
137 | |
82 | Example: make sure we haven't accidentally been linked against the wrong |
138 | Example: Make sure we haven't accidentally been linked against the wrong |
83 | version: |
139 | version. |
84 | |
140 | |
85 | assert (("libev version mismatch", |
141 | assert (("libev version mismatch", |
86 | ev_version_major () == EV_VERSION_MAJOR |
142 | ev_version_major () == EV_VERSION_MAJOR |
87 | && ev_version_minor () >= EV_VERSION_MINOR)); |
143 | && ev_version_minor () >= EV_VERSION_MINOR)); |
88 | |
144 | |
… | |
… | |
118 | |
174 | |
119 | See the description of C<ev_embed> watchers for more info. |
175 | See the description of C<ev_embed> watchers for more info. |
120 | |
176 | |
121 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
177 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
122 | |
178 | |
123 | Sets the allocation function to use (the prototype is similar to the |
179 | Sets the allocation function to use (the prototype is similar - the |
124 | realloc C function, the semantics are identical). It is used to allocate |
180 | semantics is identical - to the realloc C function). It is used to |
125 | and free memory (no surprises here). If it returns zero when memory |
181 | allocate and free memory (no surprises here). If it returns zero when |
126 | needs to be allocated, the library might abort or take some potentially |
182 | memory needs to be allocated, the library might abort or take some |
127 | destructive action. The default is your system realloc function. |
183 | potentially destructive action. The default is your system realloc |
|
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184 | function. |
128 | |
185 | |
129 | You could override this function in high-availability programs to, say, |
186 | You could override this function in high-availability programs to, say, |
130 | free some memory if it cannot allocate memory, to use a special allocator, |
187 | free some memory if it cannot allocate memory, to use a special allocator, |
131 | or even to sleep a while and retry until some memory is available. |
188 | or even to sleep a while and retry until some memory is available. |
132 | |
189 | |
133 | Example: replace the libev allocator with one that waits a bit and then |
190 | Example: Replace the libev allocator with one that waits a bit and then |
134 | retries: better than mine). |
191 | retries). |
135 | |
192 | |
136 | static void * |
193 | static void * |
137 | persistent_realloc (void *ptr, long size) |
194 | persistent_realloc (void *ptr, size_t size) |
138 | { |
195 | { |
139 | for (;;) |
196 | for (;;) |
140 | { |
197 | { |
141 | void *newptr = realloc (ptr, size); |
198 | void *newptr = realloc (ptr, size); |
142 | |
199 | |
… | |
… | |
158 | callback is set, then libev will expect it to remedy the sitution, no |
215 | callback is set, then libev will expect it to remedy the sitution, no |
159 | matter what, when it returns. That is, libev will generally retry the |
216 | matter what, when it returns. That is, libev will generally retry the |
160 | requested operation, or, if the condition doesn't go away, do bad stuff |
217 | requested operation, or, if the condition doesn't go away, do bad stuff |
161 | (such as abort). |
218 | (such as abort). |
162 | |
219 | |
163 | Example: do the same thing as libev does internally: |
220 | Example: This is basically the same thing that libev does internally, too. |
164 | |
221 | |
165 | static void |
222 | static void |
166 | fatal_error (const char *msg) |
223 | fatal_error (const char *msg) |
167 | { |
224 | { |
168 | perror (msg); |
225 | perror (msg); |
… | |
… | |
218 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
275 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
219 | override the flags completely if it is found in the environment. This is |
276 | override the flags completely if it is found in the environment. This is |
220 | useful to try out specific backends to test their performance, or to work |
277 | useful to try out specific backends to test their performance, or to work |
221 | around bugs. |
278 | around bugs. |
222 | |
279 | |
|
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280 | =item C<EVFLAG_FORKCHECK> |
|
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281 | |
|
|
282 | Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after |
|
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283 | a fork, you can also make libev check for a fork in each iteration by |
|
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284 | enabling this flag. |
|
|
285 | |
|
|
286 | This works by calling C<getpid ()> on every iteration of the loop, |
|
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287 | and thus this might slow down your event loop if you do a lot of loop |
|
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288 | iterations and little real work, but is usually not noticeable (on my |
|
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289 | Linux system for example, C<getpid> is actually a simple 5-insn sequence |
|
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290 | without a syscall and thus I<very> fast, but my Linux system also has |
|
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291 | C<pthread_atfork> which is even faster). |
|
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292 | |
|
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293 | The big advantage of this flag is that you can forget about fork (and |
|
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294 | forget about forgetting to tell libev about forking) when you use this |
|
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295 | flag. |
|
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296 | |
|
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297 | This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS> |
|
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298 | environment variable. |
|
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299 | |
223 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
300 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
224 | |
301 | |
225 | This is your standard select(2) backend. Not I<completely> standard, as |
302 | This is your standard select(2) backend. Not I<completely> standard, as |
226 | libev tries to roll its own fd_set with no limits on the number of fds, |
303 | libev tries to roll its own fd_set with no limits on the number of fds, |
227 | but if that fails, expect a fairly low limit on the number of fds when |
304 | but if that fails, expect a fairly low limit on the number of fds when |
… | |
… | |
236 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds). |
313 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds). |
237 | |
314 | |
238 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
315 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
239 | |
316 | |
240 | For few fds, this backend is a bit little slower than poll and select, |
317 | For few fds, this backend is a bit little slower than poll and select, |
241 | but it scales phenomenally better. While poll and select usually scale like |
318 | but it scales phenomenally better. While poll and select usually scale |
242 | O(total_fds) where n is the total number of fds (or the highest fd), epoll scales |
319 | like O(total_fds) where n is the total number of fds (or the highest fd), |
243 | either O(1) or O(active_fds). |
320 | epoll scales either O(1) or O(active_fds). The epoll design has a number |
|
|
321 | of shortcomings, such as silently dropping events in some hard-to-detect |
|
|
322 | cases and rewuiring a syscall per fd change, no fork support and bad |
|
|
323 | support for dup: |
244 | |
324 | |
245 | While stopping and starting an I/O watcher in the same iteration will |
325 | While stopping, setting and starting an I/O watcher in the same iteration |
246 | result in some caching, there is still a syscall per such incident |
326 | will result in some caching, there is still a syscall per such incident |
247 | (because the fd could point to a different file description now), so its |
327 | (because the fd could point to a different file description now), so its |
248 | best to avoid that. Also, dup()ed file descriptors might not work very |
328 | best to avoid that. Also, C<dup ()>'ed file descriptors might not work |
249 | well if you register events for both fds. |
329 | very well if you register events for both fds. |
250 | |
330 | |
251 | Please note that epoll sometimes generates spurious notifications, so you |
331 | Please note that epoll sometimes generates spurious notifications, so you |
252 | need to use non-blocking I/O or other means to avoid blocking when no data |
332 | need to use non-blocking I/O or other means to avoid blocking when no data |
253 | (or space) is available. |
333 | (or space) is available. |
254 | |
334 | |
255 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
335 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
256 | |
336 | |
257 | Kqueue deserves special mention, as at the time of this writing, it |
337 | Kqueue deserves special mention, as at the time of this writing, it |
258 | was broken on all BSDs except NetBSD (usually it doesn't work with |
338 | was broken on I<all> BSDs (usually it doesn't work with anything but |
259 | anything but sockets and pipes, except on Darwin, where of course its |
339 | sockets and pipes, except on Darwin, where of course it's completely |
|
|
340 | useless. On NetBSD, it seems to work for all the FD types I tested, so it |
260 | completely useless). For this reason its not being "autodetected" |
341 | is used by default there). For this reason it's not being "autodetected" |
261 | unless you explicitly specify it explicitly in the flags (i.e. using |
342 | unless you explicitly specify it explicitly in the flags (i.e. using |
262 | C<EVBACKEND_KQUEUE>). |
343 | C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough) |
|
|
344 | system like NetBSD. |
263 | |
345 | |
264 | It scales in the same way as the epoll backend, but the interface to the |
346 | It scales in the same way as the epoll backend, but the interface to the |
265 | kernel is more efficient (which says nothing about its actual speed, of |
347 | kernel is more efficient (which says nothing about its actual speed, |
266 | course). While starting and stopping an I/O watcher does not cause an |
348 | of course). While stopping, setting and starting an I/O watcher does |
267 | extra syscall as with epoll, it still adds up to four event changes per |
349 | never cause an extra syscall as with epoll, it still adds up to two event |
268 | incident, so its best to avoid that. |
350 | changes per incident, support for C<fork ()> is very bad and it drops fds |
|
|
351 | silently in similarly hard-to-detetc cases. |
269 | |
352 | |
270 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
353 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
271 | |
354 | |
272 | This is not implemented yet (and might never be). |
355 | This is not implemented yet (and might never be). |
273 | |
356 | |
274 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
357 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
275 | |
358 | |
276 | This uses the Solaris 10 port mechanism. As with everything on Solaris, |
359 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
277 | it's really slow, but it still scales very well (O(active_fds)). |
360 | it's really slow, but it still scales very well (O(active_fds)). |
278 | |
361 | |
279 | Please note that solaris ports can result in a lot of spurious |
362 | Please note that solaris event ports can deliver a lot of spurious |
280 | notifications, so you need to use non-blocking I/O or other means to avoid |
363 | notifications, so you need to use non-blocking I/O or other means to avoid |
281 | blocking when no data (or space) is available. |
364 | blocking when no data (or space) is available. |
282 | |
365 | |
283 | =item C<EVBACKEND_ALL> |
366 | =item C<EVBACKEND_ALL> |
284 | |
367 | |
… | |
… | |
314 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
397 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
315 | always distinct from the default loop. Unlike the default loop, it cannot |
398 | always distinct from the default loop. Unlike the default loop, it cannot |
316 | handle signal and child watchers, and attempts to do so will be greeted by |
399 | handle signal and child watchers, and attempts to do so will be greeted by |
317 | undefined behaviour (or a failed assertion if assertions are enabled). |
400 | undefined behaviour (or a failed assertion if assertions are enabled). |
318 | |
401 | |
319 | Example: try to create a event loop that uses epoll and nothing else. |
402 | Example: Try to create a event loop that uses epoll and nothing else. |
320 | |
403 | |
321 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
404 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
322 | if (!epoller) |
405 | if (!epoller) |
323 | fatal ("no epoll found here, maybe it hides under your chair"); |
406 | fatal ("no epoll found here, maybe it hides under your chair"); |
324 | |
407 | |
… | |
… | |
327 | Destroys the default loop again (frees all memory and kernel state |
410 | Destroys the default loop again (frees all memory and kernel state |
328 | etc.). None of the active event watchers will be stopped in the normal |
411 | etc.). None of the active event watchers will be stopped in the normal |
329 | sense, so e.g. C<ev_is_active> might still return true. It is your |
412 | sense, so e.g. C<ev_is_active> might still return true. It is your |
330 | responsibility to either stop all watchers cleanly yoursef I<before> |
413 | responsibility to either stop all watchers cleanly yoursef I<before> |
331 | calling this function, or cope with the fact afterwards (which is usually |
414 | calling this function, or cope with the fact afterwards (which is usually |
332 | the easiest thing, youc na just ignore the watchers and/or C<free ()> them |
415 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
333 | for example). |
416 | for example). |
|
|
417 | |
|
|
418 | Note that certain global state, such as signal state, will not be freed by |
|
|
419 | this function, and related watchers (such as signal and child watchers) |
|
|
420 | would need to be stopped manually. |
|
|
421 | |
|
|
422 | In general it is not advisable to call this function except in the |
|
|
423 | rare occasion where you really need to free e.g. the signal handling |
|
|
424 | pipe fds. If you need dynamically allocated loops it is better to use |
|
|
425 | C<ev_loop_new> and C<ev_loop_destroy>). |
334 | |
426 | |
335 | =item ev_loop_destroy (loop) |
427 | =item ev_loop_destroy (loop) |
336 | |
428 | |
337 | Like C<ev_default_destroy>, but destroys an event loop created by an |
429 | Like C<ev_default_destroy>, but destroys an event loop created by an |
338 | earlier call to C<ev_loop_new>. |
430 | earlier call to C<ev_loop_new>. |
… | |
… | |
362 | |
454 | |
363 | Like C<ev_default_fork>, but acts on an event loop created by |
455 | Like C<ev_default_fork>, but acts on an event loop created by |
364 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
456 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
365 | after fork, and how you do this is entirely your own problem. |
457 | after fork, and how you do this is entirely your own problem. |
366 | |
458 | |
|
|
459 | =item unsigned int ev_loop_count (loop) |
|
|
460 | |
|
|
461 | Returns the count of loop iterations for the loop, which is identical to |
|
|
462 | the number of times libev did poll for new events. It starts at C<0> and |
|
|
463 | happily wraps around with enough iterations. |
|
|
464 | |
|
|
465 | This value can sometimes be useful as a generation counter of sorts (it |
|
|
466 | "ticks" the number of loop iterations), as it roughly corresponds with |
|
|
467 | C<ev_prepare> and C<ev_check> calls. |
|
|
468 | |
367 | =item unsigned int ev_backend (loop) |
469 | =item unsigned int ev_backend (loop) |
368 | |
470 | |
369 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
471 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
370 | use. |
472 | use. |
371 | |
473 | |
… | |
… | |
373 | |
475 | |
374 | Returns the current "event loop time", which is the time the event loop |
476 | Returns the current "event loop time", which is the time the event loop |
375 | received events and started processing them. This timestamp does not |
477 | received events and started processing them. This timestamp does not |
376 | change as long as callbacks are being processed, and this is also the base |
478 | change as long as callbacks are being processed, and this is also the base |
377 | time used for relative timers. You can treat it as the timestamp of the |
479 | time used for relative timers. You can treat it as the timestamp of the |
378 | event occuring (or more correctly, libev finding out about it). |
480 | event occurring (or more correctly, libev finding out about it). |
379 | |
481 | |
380 | =item ev_loop (loop, int flags) |
482 | =item ev_loop (loop, int flags) |
381 | |
483 | |
382 | Finally, this is it, the event handler. This function usually is called |
484 | Finally, this is it, the event handler. This function usually is called |
383 | after you initialised all your watchers and you want to start handling |
485 | after you initialised all your watchers and you want to start handling |
… | |
… | |
404 | libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is |
506 | libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is |
405 | usually a better approach for this kind of thing. |
507 | usually a better approach for this kind of thing. |
406 | |
508 | |
407 | Here are the gory details of what C<ev_loop> does: |
509 | Here are the gory details of what C<ev_loop> does: |
408 | |
510 | |
|
|
511 | - Before the first iteration, call any pending watchers. |
409 | * If there are no active watchers (reference count is zero), return. |
512 | * If there are no active watchers (reference count is zero), return. |
410 | - Queue prepare watchers and then call all outstanding watchers. |
513 | - Queue all prepare watchers and then call all outstanding watchers. |
411 | - If we have been forked, recreate the kernel state. |
514 | - If we have been forked, recreate the kernel state. |
412 | - Update the kernel state with all outstanding changes. |
515 | - Update the kernel state with all outstanding changes. |
413 | - Update the "event loop time". |
516 | - Update the "event loop time". |
414 | - Calculate for how long to block. |
517 | - Calculate for how long to block. |
415 | - Block the process, waiting for any events. |
518 | - Block the process, waiting for any events. |
… | |
… | |
423 | Signals and child watchers are implemented as I/O watchers, and will |
526 | Signals and child watchers are implemented as I/O watchers, and will |
424 | be handled here by queueing them when their watcher gets executed. |
527 | be handled here by queueing them when their watcher gets executed. |
425 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
528 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
426 | were used, return, otherwise continue with step *. |
529 | were used, return, otherwise continue with step *. |
427 | |
530 | |
428 | Example: queue some jobs and then loop until no events are outsanding |
531 | Example: Queue some jobs and then loop until no events are outsanding |
429 | anymore. |
532 | anymore. |
430 | |
533 | |
431 | ... queue jobs here, make sure they register event watchers as long |
534 | ... queue jobs here, make sure they register event watchers as long |
432 | ... as they still have work to do (even an idle watcher will do..) |
535 | ... as they still have work to do (even an idle watcher will do..) |
433 | ev_loop (my_loop, 0); |
536 | ev_loop (my_loop, 0); |
… | |
… | |
453 | visible to the libev user and should not keep C<ev_loop> from exiting if |
556 | visible to the libev user and should not keep C<ev_loop> from exiting if |
454 | no event watchers registered by it are active. It is also an excellent |
557 | no event watchers registered by it are active. It is also an excellent |
455 | way to do this for generic recurring timers or from within third-party |
558 | way to do this for generic recurring timers or from within third-party |
456 | libraries. Just remember to I<unref after start> and I<ref before stop>. |
559 | libraries. Just remember to I<unref after start> and I<ref before stop>. |
457 | |
560 | |
458 | Example: create a signal watcher, but keep it from keeping C<ev_loop> |
561 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
459 | running when nothing else is active. |
562 | running when nothing else is active. |
460 | |
563 | |
461 | struct dv_signal exitsig; |
564 | struct ev_signal exitsig; |
462 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
565 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
463 | ev_signal_start (myloop, &exitsig); |
566 | ev_signal_start (loop, &exitsig); |
464 | evf_unref (myloop); |
567 | evf_unref (loop); |
465 | |
568 | |
466 | Example: for some weird reason, unregister the above signal handler again. |
569 | Example: For some weird reason, unregister the above signal handler again. |
467 | |
570 | |
468 | ev_ref (myloop); |
571 | ev_ref (loop); |
469 | ev_signal_stop (myloop, &exitsig); |
572 | ev_signal_stop (loop, &exitsig); |
470 | |
573 | |
471 | =back |
574 | =back |
|
|
575 | |
472 | |
576 | |
473 | =head1 ANATOMY OF A WATCHER |
577 | =head1 ANATOMY OF A WATCHER |
474 | |
578 | |
475 | A watcher is a structure that you create and register to record your |
579 | A watcher is a structure that you create and register to record your |
476 | interest in some event. For instance, if you want to wait for STDIN to |
580 | interest in some event. For instance, if you want to wait for STDIN to |
… | |
… | |
543 | The signal specified in the C<ev_signal> watcher has been received by a thread. |
647 | The signal specified in the C<ev_signal> watcher has been received by a thread. |
544 | |
648 | |
545 | =item C<EV_CHILD> |
649 | =item C<EV_CHILD> |
546 | |
650 | |
547 | The pid specified in the C<ev_child> watcher has received a status change. |
651 | The pid specified in the C<ev_child> watcher has received a status change. |
|
|
652 | |
|
|
653 | =item C<EV_STAT> |
|
|
654 | |
|
|
655 | The path specified in the C<ev_stat> watcher changed its attributes somehow. |
548 | |
656 | |
549 | =item C<EV_IDLE> |
657 | =item C<EV_IDLE> |
550 | |
658 | |
551 | The C<ev_idle> watcher has determined that you have nothing better to do. |
659 | The C<ev_idle> watcher has determined that you have nothing better to do. |
552 | |
660 | |
… | |
… | |
560 | received events. Callbacks of both watcher types can start and stop as |
668 | received events. Callbacks of both watcher types can start and stop as |
561 | many watchers as they want, and all of them will be taken into account |
669 | many watchers as they want, and all of them will be taken into account |
562 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
670 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
563 | C<ev_loop> from blocking). |
671 | C<ev_loop> from blocking). |
564 | |
672 | |
|
|
673 | =item C<EV_EMBED> |
|
|
674 | |
|
|
675 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
|
|
676 | |
|
|
677 | =item C<EV_FORK> |
|
|
678 | |
|
|
679 | The event loop has been resumed in the child process after fork (see |
|
|
680 | C<ev_fork>). |
|
|
681 | |
565 | =item C<EV_ERROR> |
682 | =item C<EV_ERROR> |
566 | |
683 | |
567 | An unspecified error has occured, the watcher has been stopped. This might |
684 | An unspecified error has occured, the watcher has been stopped. This might |
568 | happen because the watcher could not be properly started because libev |
685 | happen because the watcher could not be properly started because libev |
569 | ran out of memory, a file descriptor was found to be closed or any other |
686 | ran out of memory, a file descriptor was found to be closed or any other |
… | |
… | |
576 | with the error from read() or write(). This will not work in multithreaded |
693 | with the error from read() or write(). This will not work in multithreaded |
577 | programs, though, so beware. |
694 | programs, though, so beware. |
578 | |
695 | |
579 | =back |
696 | =back |
580 | |
697 | |
581 | =head2 SUMMARY OF GENERIC WATCHER FUNCTIONS |
698 | =head2 GENERIC WATCHER FUNCTIONS |
582 | |
699 | |
583 | In the following description, C<TYPE> stands for the watcher type, |
700 | In the following description, C<TYPE> stands for the watcher type, |
584 | e.g. C<timer> for C<ev_timer> watchers and C<io> for C<ev_io> watchers. |
701 | e.g. C<timer> for C<ev_timer> watchers and C<io> for C<ev_io> watchers. |
585 | |
702 | |
586 | =over 4 |
703 | =over 4 |
… | |
… | |
595 | which rolls both calls into one. |
712 | which rolls both calls into one. |
596 | |
713 | |
597 | You can reinitialise a watcher at any time as long as it has been stopped |
714 | You can reinitialise a watcher at any time as long as it has been stopped |
598 | (or never started) and there are no pending events outstanding. |
715 | (or never started) and there are no pending events outstanding. |
599 | |
716 | |
600 | The callbakc is always of type C<void (*)(ev_loop *loop, ev_TYPE *watcher, |
717 | The callback is always of type C<void (*)(ev_loop *loop, ev_TYPE *watcher, |
601 | int revents)>. |
718 | int revents)>. |
602 | |
719 | |
603 | =item C<ev_TYPE_set> (ev_TYPE *, [args]) |
720 | =item C<ev_TYPE_set> (ev_TYPE *, [args]) |
604 | |
721 | |
605 | This macro initialises the type-specific parts of a watcher. You need to |
722 | This macro initialises the type-specific parts of a watcher. You need to |
… | |
… | |
640 | =item bool ev_is_pending (ev_TYPE *watcher) |
757 | =item bool ev_is_pending (ev_TYPE *watcher) |
641 | |
758 | |
642 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
759 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
643 | events but its callback has not yet been invoked). As long as a watcher |
760 | events but its callback has not yet been invoked). As long as a watcher |
644 | is pending (but not active) you must not call an init function on it (but |
761 | is pending (but not active) you must not call an init function on it (but |
645 | C<ev_TYPE_set> is safe) and you must make sure the watcher is available to |
762 | C<ev_TYPE_set> is safe), you must not change its priority, and you must |
646 | libev (e.g. you cnanot C<free ()> it). |
763 | make sure the watcher is available to libev (e.g. you cannot C<free ()> |
|
|
764 | it). |
647 | |
765 | |
648 | =item callback = ev_cb (ev_TYPE *watcher) |
766 | =item callback ev_cb (ev_TYPE *watcher) |
649 | |
767 | |
650 | Returns the callback currently set on the watcher. |
768 | Returns the callback currently set on the watcher. |
651 | |
769 | |
652 | =item ev_cb_set (ev_TYPE *watcher, callback) |
770 | =item ev_cb_set (ev_TYPE *watcher, callback) |
653 | |
771 | |
654 | Change the callback. You can change the callback at virtually any time |
772 | Change the callback. You can change the callback at virtually any time |
655 | (modulo threads). |
773 | (modulo threads). |
|
|
774 | |
|
|
775 | =item ev_set_priority (ev_TYPE *watcher, priority) |
|
|
776 | |
|
|
777 | =item int ev_priority (ev_TYPE *watcher) |
|
|
778 | |
|
|
779 | Set and query the priority of the watcher. The priority is a small |
|
|
780 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
|
|
781 | (default: C<-2>). Pending watchers with higher priority will be invoked |
|
|
782 | before watchers with lower priority, but priority will not keep watchers |
|
|
783 | from being executed (except for C<ev_idle> watchers). |
|
|
784 | |
|
|
785 | This means that priorities are I<only> used for ordering callback |
|
|
786 | invocation after new events have been received. This is useful, for |
|
|
787 | example, to reduce latency after idling, or more often, to bind two |
|
|
788 | watchers on the same event and make sure one is called first. |
|
|
789 | |
|
|
790 | If you need to suppress invocation when higher priority events are pending |
|
|
791 | you need to look at C<ev_idle> watchers, which provide this functionality. |
|
|
792 | |
|
|
793 | You I<must not> change the priority of a watcher as long as it is active or |
|
|
794 | pending. |
|
|
795 | |
|
|
796 | The default priority used by watchers when no priority has been set is |
|
|
797 | always C<0>, which is supposed to not be too high and not be too low :). |
|
|
798 | |
|
|
799 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
|
|
800 | fine, as long as you do not mind that the priority value you query might |
|
|
801 | or might not have been adjusted to be within valid range. |
|
|
802 | |
|
|
803 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
|
|
804 | |
|
|
805 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
|
|
806 | C<loop> nor C<revents> need to be valid as long as the watcher callback |
|
|
807 | can deal with that fact. |
|
|
808 | |
|
|
809 | =item int ev_clear_pending (loop, ev_TYPE *watcher) |
|
|
810 | |
|
|
811 | If the watcher is pending, this function returns clears its pending status |
|
|
812 | and returns its C<revents> bitset (as if its callback was invoked). If the |
|
|
813 | watcher isn't pending it does nothing and returns C<0>. |
656 | |
814 | |
657 | =back |
815 | =back |
658 | |
816 | |
659 | |
817 | |
660 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
818 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
… | |
… | |
681 | { |
839 | { |
682 | struct my_io *w = (struct my_io *)w_; |
840 | struct my_io *w = (struct my_io *)w_; |
683 | ... |
841 | ... |
684 | } |
842 | } |
685 | |
843 | |
686 | More interesting and less C-conformant ways of catsing your callback type |
844 | More interesting and less C-conformant ways of casting your callback type |
687 | have been omitted.... |
845 | instead have been omitted. |
|
|
846 | |
|
|
847 | Another common scenario is having some data structure with multiple |
|
|
848 | watchers: |
|
|
849 | |
|
|
850 | struct my_biggy |
|
|
851 | { |
|
|
852 | int some_data; |
|
|
853 | ev_timer t1; |
|
|
854 | ev_timer t2; |
|
|
855 | } |
|
|
856 | |
|
|
857 | In this case getting the pointer to C<my_biggy> is a bit more complicated, |
|
|
858 | you need to use C<offsetof>: |
|
|
859 | |
|
|
860 | #include <stddef.h> |
|
|
861 | |
|
|
862 | static void |
|
|
863 | t1_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
864 | { |
|
|
865 | struct my_biggy big = (struct my_biggy * |
|
|
866 | (((char *)w) - offsetof (struct my_biggy, t1)); |
|
|
867 | } |
|
|
868 | |
|
|
869 | static void |
|
|
870 | t2_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
871 | { |
|
|
872 | struct my_biggy big = (struct my_biggy * |
|
|
873 | (((char *)w) - offsetof (struct my_biggy, t2)); |
|
|
874 | } |
688 | |
875 | |
689 | |
876 | |
690 | =head1 WATCHER TYPES |
877 | =head1 WATCHER TYPES |
691 | |
878 | |
692 | This section describes each watcher in detail, but will not repeat |
879 | This section describes each watcher in detail, but will not repeat |
693 | information given in the last section. |
880 | information given in the last section. Any initialisation/set macros, |
|
|
881 | functions and members specific to the watcher type are explained. |
694 | |
882 | |
|
|
883 | Members are additionally marked with either I<[read-only]>, meaning that, |
|
|
884 | while the watcher is active, you can look at the member and expect some |
|
|
885 | sensible content, but you must not modify it (you can modify it while the |
|
|
886 | watcher is stopped to your hearts content), or I<[read-write]>, which |
|
|
887 | means you can expect it to have some sensible content while the watcher |
|
|
888 | is active, but you can also modify it. Modifying it may not do something |
|
|
889 | sensible or take immediate effect (or do anything at all), but libev will |
|
|
890 | not crash or malfunction in any way. |
695 | |
891 | |
|
|
892 | |
696 | =head2 C<ev_io> - is this file descriptor readable or writable |
893 | =head2 C<ev_io> - is this file descriptor readable or writable? |
697 | |
894 | |
698 | I/O watchers check whether a file descriptor is readable or writable |
895 | I/O watchers check whether a file descriptor is readable or writable |
699 | in each iteration of the event loop (This behaviour is called |
896 | in each iteration of the event loop, or, more precisely, when reading |
700 | level-triggering because you keep receiving events as long as the |
897 | would not block the process and writing would at least be able to write |
701 | condition persists. Remember you can stop the watcher if you don't want to |
898 | some data. This behaviour is called level-triggering because you keep |
702 | act on the event and neither want to receive future events). |
899 | receiving events as long as the condition persists. Remember you can stop |
|
|
900 | the watcher if you don't want to act on the event and neither want to |
|
|
901 | receive future events. |
703 | |
902 | |
704 | In general you can register as many read and/or write event watchers per |
903 | In general you can register as many read and/or write event watchers per |
705 | fd as you want (as long as you don't confuse yourself). Setting all file |
904 | fd as you want (as long as you don't confuse yourself). Setting all file |
706 | descriptors to non-blocking mode is also usually a good idea (but not |
905 | descriptors to non-blocking mode is also usually a good idea (but not |
707 | required if you know what you are doing). |
906 | required if you know what you are doing). |
708 | |
907 | |
709 | You have to be careful with dup'ed file descriptors, though. Some backends |
908 | You have to be careful with dup'ed file descriptors, though. Some backends |
710 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
909 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
711 | descriptors correctly if you register interest in two or more fds pointing |
910 | descriptors correctly if you register interest in two or more fds pointing |
712 | to the same underlying file/socket etc. description (that is, they share |
911 | to the same underlying file/socket/etc. description (that is, they share |
713 | the same underlying "file open"). |
912 | the same underlying "file open"). |
714 | |
913 | |
715 | If you must do this, then force the use of a known-to-be-good backend |
914 | If you must do this, then force the use of a known-to-be-good backend |
716 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
915 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
717 | C<EVBACKEND_POLL>). |
916 | C<EVBACKEND_POLL>). |
718 | |
917 | |
|
|
918 | Another thing you have to watch out for is that it is quite easy to |
|
|
919 | receive "spurious" readyness notifications, that is your callback might |
|
|
920 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
|
|
921 | because there is no data. Not only are some backends known to create a |
|
|
922 | lot of those (for example solaris ports), it is very easy to get into |
|
|
923 | this situation even with a relatively standard program structure. Thus |
|
|
924 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
|
|
925 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
|
|
926 | |
|
|
927 | If you cannot run the fd in non-blocking mode (for example you should not |
|
|
928 | play around with an Xlib connection), then you have to seperately re-test |
|
|
929 | whether a file descriptor is really ready with a known-to-be good interface |
|
|
930 | such as poll (fortunately in our Xlib example, Xlib already does this on |
|
|
931 | its own, so its quite safe to use). |
|
|
932 | |
|
|
933 | =head3 The special problem of disappearing file descriptors |
|
|
934 | |
|
|
935 | Some backends (e.g. kqueue, epoll) need to be told about closing a file |
|
|
936 | descriptor (either by calling C<close> explicitly or by any other means, |
|
|
937 | such as C<dup>). The reason is that you register interest in some file |
|
|
938 | descriptor, but when it goes away, the operating system will silently drop |
|
|
939 | this interest. If another file descriptor with the same number then is |
|
|
940 | registered with libev, there is no efficient way to see that this is, in |
|
|
941 | fact, a different file descriptor. |
|
|
942 | |
|
|
943 | To avoid having to explicitly tell libev about such cases, libev follows |
|
|
944 | the following policy: Each time C<ev_io_set> is being called, libev |
|
|
945 | will assume that this is potentially a new file descriptor, otherwise |
|
|
946 | it is assumed that the file descriptor stays the same. That means that |
|
|
947 | you I<have> to call C<ev_io_set> (or C<ev_io_init>) when you change the |
|
|
948 | descriptor even if the file descriptor number itself did not change. |
|
|
949 | |
|
|
950 | This is how one would do it normally anyway, the important point is that |
|
|
951 | the libev application should not optimise around libev but should leave |
|
|
952 | optimisations to libev. |
|
|
953 | |
|
|
954 | =head3 The special problem of dup'ed file descriptors |
|
|
955 | |
|
|
956 | Some backends (e.g. epoll), cannot register events for file descriptors, |
|
|
957 | but only events for the underlying file descriptions. That menas when you |
|
|
958 | have C<dup ()>'ed file descriptors and register events for them, only one |
|
|
959 | file descriptor might actually receive events. |
|
|
960 | |
|
|
961 | There is no workaorund possible except not registering events |
|
|
962 | for potentially C<dup ()>'ed file descriptors or to resort to |
|
|
963 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
|
|
964 | |
|
|
965 | =head3 The special problem of fork |
|
|
966 | |
|
|
967 | Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit |
|
|
968 | useless behaviour. Libev fully supports fork, but needs to be told about |
|
|
969 | it in the child. |
|
|
970 | |
|
|
971 | To support fork in your programs, you either have to call |
|
|
972 | C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child, |
|
|
973 | enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or |
|
|
974 | C<EVBACKEND_POLL>. |
|
|
975 | |
|
|
976 | |
|
|
977 | =head3 Watcher-Specific Functions |
|
|
978 | |
719 | =over 4 |
979 | =over 4 |
720 | |
980 | |
721 | =item ev_io_init (ev_io *, callback, int fd, int events) |
981 | =item ev_io_init (ev_io *, callback, int fd, int events) |
722 | |
982 | |
723 | =item ev_io_set (ev_io *, int fd, int events) |
983 | =item ev_io_set (ev_io *, int fd, int events) |
724 | |
984 | |
725 | Configures an C<ev_io> watcher. The fd is the file descriptor to rceeive |
985 | Configures an C<ev_io> watcher. The C<fd> is the file descriptor to |
726 | events for and events is either C<EV_READ>, C<EV_WRITE> or C<EV_READ | |
986 | rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or |
727 | EV_WRITE> to receive the given events. |
987 | C<EV_READ | EV_WRITE> to receive the given events. |
728 | |
988 | |
729 | Please note that most of the more scalable backend mechanisms (for example |
989 | =item int fd [read-only] |
730 | epoll and solaris ports) can result in spurious readyness notifications |
990 | |
731 | for file descriptors, so you practically need to use non-blocking I/O (and |
991 | The file descriptor being watched. |
732 | treat callback invocation as hint only), or retest separately with a safe |
992 | |
733 | interface before doing I/O (XLib can do this), or force the use of either |
993 | =item int events [read-only] |
734 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>, which don't suffer from this |
994 | |
735 | problem. Also note that it is quite easy to have your callback invoked |
995 | The events being watched. |
736 | when the readyness condition is no longer valid even when employing |
|
|
737 | typical ways of handling events, so its a good idea to use non-blocking |
|
|
738 | I/O unconditionally. |
|
|
739 | |
996 | |
740 | =back |
997 | =back |
741 | |
998 | |
742 | Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well |
999 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
743 | readable, but only once. Since it is likely line-buffered, you could |
1000 | readable, but only once. Since it is likely line-buffered, you could |
744 | attempt to read a whole line in the callback: |
1001 | attempt to read a whole line in the callback. |
745 | |
1002 | |
746 | static void |
1003 | static void |
747 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1004 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
748 | { |
1005 | { |
749 | ev_io_stop (loop, w); |
1006 | ev_io_stop (loop, w); |
… | |
… | |
756 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1013 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
757 | ev_io_start (loop, &stdin_readable); |
1014 | ev_io_start (loop, &stdin_readable); |
758 | ev_loop (loop, 0); |
1015 | ev_loop (loop, 0); |
759 | |
1016 | |
760 | |
1017 | |
761 | =head2 C<ev_timer> - relative and optionally recurring timeouts |
1018 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
762 | |
1019 | |
763 | Timer watchers are simple relative timers that generate an event after a |
1020 | Timer watchers are simple relative timers that generate an event after a |
764 | given time, and optionally repeating in regular intervals after that. |
1021 | given time, and optionally repeating in regular intervals after that. |
765 | |
1022 | |
766 | The timers are based on real time, that is, if you register an event that |
1023 | The timers are based on real time, that is, if you register an event that |
… | |
… | |
779 | |
1036 | |
780 | The callback is guarenteed to be invoked only when its timeout has passed, |
1037 | The callback is guarenteed to be invoked only when its timeout has passed, |
781 | but if multiple timers become ready during the same loop iteration then |
1038 | but if multiple timers become ready during the same loop iteration then |
782 | order of execution is undefined. |
1039 | order of execution is undefined. |
783 | |
1040 | |
|
|
1041 | =head3 Watcher-Specific Functions and Data Members |
|
|
1042 | |
784 | =over 4 |
1043 | =over 4 |
785 | |
1044 | |
786 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
1045 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
787 | |
1046 | |
788 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
1047 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
… | |
… | |
801 | =item ev_timer_again (loop) |
1060 | =item ev_timer_again (loop) |
802 | |
1061 | |
803 | This will act as if the timer timed out and restart it again if it is |
1062 | This will act as if the timer timed out and restart it again if it is |
804 | repeating. The exact semantics are: |
1063 | repeating. The exact semantics are: |
805 | |
1064 | |
|
|
1065 | If the timer is pending, its pending status is cleared. |
|
|
1066 | |
806 | If the timer is started but nonrepeating, stop it. |
1067 | If the timer is started but nonrepeating, stop it (as if it timed out). |
807 | |
1068 | |
808 | If the timer is repeating, either start it if necessary (with the repeat |
1069 | If the timer is repeating, either start it if necessary (with the |
809 | value), or reset the running timer to the repeat value. |
1070 | C<repeat> value), or reset the running timer to the C<repeat> value. |
810 | |
1071 | |
811 | This sounds a bit complicated, but here is a useful and typical |
1072 | This sounds a bit complicated, but here is a useful and typical |
812 | example: Imagine you have a tcp connection and you want a so-called idle |
1073 | example: Imagine you have a tcp connection and you want a so-called idle |
813 | timeout, that is, you want to be called when there have been, say, 60 |
1074 | timeout, that is, you want to be called when there have been, say, 60 |
814 | seconds of inactivity on the socket. The easiest way to do this is to |
1075 | seconds of inactivity on the socket. The easiest way to do this is to |
815 | configure an C<ev_timer> with after=repeat=60 and calling ev_timer_again each |
1076 | configure an C<ev_timer> with a C<repeat> value of C<60> and then call |
816 | time you successfully read or write some data. If you go into an idle |
1077 | C<ev_timer_again> each time you successfully read or write some data. If |
817 | state where you do not expect data to travel on the socket, you can stop |
1078 | you go into an idle state where you do not expect data to travel on the |
818 | the timer, and again will automatically restart it if need be. |
1079 | socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will |
|
|
1080 | automatically restart it if need be. |
|
|
1081 | |
|
|
1082 | That means you can ignore the C<after> value and C<ev_timer_start> |
|
|
1083 | altogether and only ever use the C<repeat> value and C<ev_timer_again>: |
|
|
1084 | |
|
|
1085 | ev_timer_init (timer, callback, 0., 5.); |
|
|
1086 | ev_timer_again (loop, timer); |
|
|
1087 | ... |
|
|
1088 | timer->again = 17.; |
|
|
1089 | ev_timer_again (loop, timer); |
|
|
1090 | ... |
|
|
1091 | timer->again = 10.; |
|
|
1092 | ev_timer_again (loop, timer); |
|
|
1093 | |
|
|
1094 | This is more slightly efficient then stopping/starting the timer each time |
|
|
1095 | you want to modify its timeout value. |
|
|
1096 | |
|
|
1097 | =item ev_tstamp repeat [read-write] |
|
|
1098 | |
|
|
1099 | The current C<repeat> value. Will be used each time the watcher times out |
|
|
1100 | or C<ev_timer_again> is called and determines the next timeout (if any), |
|
|
1101 | which is also when any modifications are taken into account. |
819 | |
1102 | |
820 | =back |
1103 | =back |
821 | |
1104 | |
822 | Example: create a timer that fires after 60 seconds. |
1105 | Example: Create a timer that fires after 60 seconds. |
823 | |
1106 | |
824 | static void |
1107 | static void |
825 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1108 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
826 | { |
1109 | { |
827 | .. one minute over, w is actually stopped right here |
1110 | .. one minute over, w is actually stopped right here |
… | |
… | |
829 | |
1112 | |
830 | struct ev_timer mytimer; |
1113 | struct ev_timer mytimer; |
831 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
1114 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
832 | ev_timer_start (loop, &mytimer); |
1115 | ev_timer_start (loop, &mytimer); |
833 | |
1116 | |
834 | Example: create a timeout timer that times out after 10 seconds of |
1117 | Example: Create a timeout timer that times out after 10 seconds of |
835 | inactivity. |
1118 | inactivity. |
836 | |
1119 | |
837 | static void |
1120 | static void |
838 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1121 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
839 | { |
1122 | { |
… | |
… | |
848 | // and in some piece of code that gets executed on any "activity": |
1131 | // and in some piece of code that gets executed on any "activity": |
849 | // reset the timeout to start ticking again at 10 seconds |
1132 | // reset the timeout to start ticking again at 10 seconds |
850 | ev_timer_again (&mytimer); |
1133 | ev_timer_again (&mytimer); |
851 | |
1134 | |
852 | |
1135 | |
853 | =head2 C<ev_periodic> - to cron or not to cron |
1136 | =head2 C<ev_periodic> - to cron or not to cron? |
854 | |
1137 | |
855 | Periodic watchers are also timers of a kind, but they are very versatile |
1138 | Periodic watchers are also timers of a kind, but they are very versatile |
856 | (and unfortunately a bit complex). |
1139 | (and unfortunately a bit complex). |
857 | |
1140 | |
858 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
1141 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
859 | but on wallclock time (absolute time). You can tell a periodic watcher |
1142 | but on wallclock time (absolute time). You can tell a periodic watcher |
860 | to trigger "at" some specific point in time. For example, if you tell a |
1143 | to trigger "at" some specific point in time. For example, if you tell a |
861 | periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now () |
1144 | periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now () |
862 | + 10.>) and then reset your system clock to the last year, then it will |
1145 | + 10.>) and then reset your system clock to the last year, then it will |
863 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
1146 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
864 | roughly 10 seconds later and of course not if you reset your system time |
1147 | roughly 10 seconds later). |
865 | again). |
|
|
866 | |
1148 | |
867 | They can also be used to implement vastly more complex timers, such as |
1149 | They can also be used to implement vastly more complex timers, such as |
868 | triggering an event on eahc midnight, local time. |
1150 | triggering an event on each midnight, local time or other, complicated, |
|
|
1151 | rules. |
869 | |
1152 | |
870 | As with timers, the callback is guarenteed to be invoked only when the |
1153 | As with timers, the callback is guarenteed to be invoked only when the |
871 | time (C<at>) has been passed, but if multiple periodic timers become ready |
1154 | time (C<at>) has been passed, but if multiple periodic timers become ready |
872 | during the same loop iteration then order of execution is undefined. |
1155 | during the same loop iteration then order of execution is undefined. |
873 | |
1156 | |
|
|
1157 | =head3 Watcher-Specific Functions and Data Members |
|
|
1158 | |
874 | =over 4 |
1159 | =over 4 |
875 | |
1160 | |
876 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
1161 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
877 | |
1162 | |
878 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
1163 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
… | |
… | |
880 | Lots of arguments, lets sort it out... There are basically three modes of |
1165 | Lots of arguments, lets sort it out... There are basically three modes of |
881 | operation, and we will explain them from simplest to complex: |
1166 | operation, and we will explain them from simplest to complex: |
882 | |
1167 | |
883 | =over 4 |
1168 | =over 4 |
884 | |
1169 | |
885 | =item * absolute timer (interval = reschedule_cb = 0) |
1170 | =item * absolute timer (at = time, interval = reschedule_cb = 0) |
886 | |
1171 | |
887 | In this configuration the watcher triggers an event at the wallclock time |
1172 | In this configuration the watcher triggers an event at the wallclock time |
888 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
1173 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
889 | that is, if it is to be run at January 1st 2011 then it will run when the |
1174 | that is, if it is to be run at January 1st 2011 then it will run when the |
890 | system time reaches or surpasses this time. |
1175 | system time reaches or surpasses this time. |
891 | |
1176 | |
892 | =item * non-repeating interval timer (interval > 0, reschedule_cb = 0) |
1177 | =item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
893 | |
1178 | |
894 | In this mode the watcher will always be scheduled to time out at the next |
1179 | In this mode the watcher will always be scheduled to time out at the next |
895 | C<at + N * interval> time (for some integer N) and then repeat, regardless |
1180 | C<at + N * interval> time (for some integer N, which can also be negative) |
896 | of any time jumps. |
1181 | and then repeat, regardless of any time jumps. |
897 | |
1182 | |
898 | This can be used to create timers that do not drift with respect to system |
1183 | This can be used to create timers that do not drift with respect to system |
899 | time: |
1184 | time: |
900 | |
1185 | |
901 | ev_periodic_set (&periodic, 0., 3600., 0); |
1186 | ev_periodic_set (&periodic, 0., 3600., 0); |
… | |
… | |
907 | |
1192 | |
908 | Another way to think about it (for the mathematically inclined) is that |
1193 | Another way to think about it (for the mathematically inclined) is that |
909 | C<ev_periodic> will try to run the callback in this mode at the next possible |
1194 | C<ev_periodic> will try to run the callback in this mode at the next possible |
910 | time where C<time = at (mod interval)>, regardless of any time jumps. |
1195 | time where C<time = at (mod interval)>, regardless of any time jumps. |
911 | |
1196 | |
|
|
1197 | For numerical stability it is preferable that the C<at> value is near |
|
|
1198 | C<ev_now ()> (the current time), but there is no range requirement for |
|
|
1199 | this value. |
|
|
1200 | |
912 | =item * manual reschedule mode (reschedule_cb = callback) |
1201 | =item * manual reschedule mode (at and interval ignored, reschedule_cb = callback) |
913 | |
1202 | |
914 | In this mode the values for C<interval> and C<at> are both being |
1203 | In this mode the values for C<interval> and C<at> are both being |
915 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1204 | ignored. Instead, each time the periodic watcher gets scheduled, the |
916 | reschedule callback will be called with the watcher as first, and the |
1205 | reschedule callback will be called with the watcher as first, and the |
917 | current time as second argument. |
1206 | current time as second argument. |
918 | |
1207 | |
919 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
1208 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
920 | ever, or make any event loop modifications>. If you need to stop it, |
1209 | ever, or make any event loop modifications>. If you need to stop it, |
921 | return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by |
1210 | return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by |
922 | starting a prepare watcher). |
1211 | starting an C<ev_prepare> watcher, which is legal). |
923 | |
1212 | |
924 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1213 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
925 | ev_tstamp now)>, e.g.: |
1214 | ev_tstamp now)>, e.g.: |
926 | |
1215 | |
927 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
1216 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
… | |
… | |
950 | Simply stops and restarts the periodic watcher again. This is only useful |
1239 | Simply stops and restarts the periodic watcher again. This is only useful |
951 | when you changed some parameters or the reschedule callback would return |
1240 | when you changed some parameters or the reschedule callback would return |
952 | a different time than the last time it was called (e.g. in a crond like |
1241 | a different time than the last time it was called (e.g. in a crond like |
953 | program when the crontabs have changed). |
1242 | program when the crontabs have changed). |
954 | |
1243 | |
|
|
1244 | =item ev_tstamp offset [read-write] |
|
|
1245 | |
|
|
1246 | When repeating, this contains the offset value, otherwise this is the |
|
|
1247 | absolute point in time (the C<at> value passed to C<ev_periodic_set>). |
|
|
1248 | |
|
|
1249 | Can be modified any time, but changes only take effect when the periodic |
|
|
1250 | timer fires or C<ev_periodic_again> is being called. |
|
|
1251 | |
|
|
1252 | =item ev_tstamp interval [read-write] |
|
|
1253 | |
|
|
1254 | The current interval value. Can be modified any time, but changes only |
|
|
1255 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
|
|
1256 | called. |
|
|
1257 | |
|
|
1258 | =item ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write] |
|
|
1259 | |
|
|
1260 | The current reschedule callback, or C<0>, if this functionality is |
|
|
1261 | switched off. Can be changed any time, but changes only take effect when |
|
|
1262 | the periodic timer fires or C<ev_periodic_again> is being called. |
|
|
1263 | |
|
|
1264 | =item ev_tstamp at [read-only] |
|
|
1265 | |
|
|
1266 | When active, contains the absolute time that the watcher is supposed to |
|
|
1267 | trigger next. |
|
|
1268 | |
955 | =back |
1269 | =back |
956 | |
1270 | |
957 | Example: call a callback every hour, or, more precisely, whenever the |
1271 | Example: Call a callback every hour, or, more precisely, whenever the |
958 | system clock is divisible by 3600. The callback invocation times have |
1272 | system clock is divisible by 3600. The callback invocation times have |
959 | potentially a lot of jittering, but good long-term stability. |
1273 | potentially a lot of jittering, but good long-term stability. |
960 | |
1274 | |
961 | static void |
1275 | static void |
962 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1276 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
… | |
… | |
966 | |
1280 | |
967 | struct ev_periodic hourly_tick; |
1281 | struct ev_periodic hourly_tick; |
968 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1282 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
969 | ev_periodic_start (loop, &hourly_tick); |
1283 | ev_periodic_start (loop, &hourly_tick); |
970 | |
1284 | |
971 | Example: the same as above, but use a reschedule callback to do it: |
1285 | Example: The same as above, but use a reschedule callback to do it: |
972 | |
1286 | |
973 | #include <math.h> |
1287 | #include <math.h> |
974 | |
1288 | |
975 | static ev_tstamp |
1289 | static ev_tstamp |
976 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
1290 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
… | |
… | |
978 | return fmod (now, 3600.) + 3600.; |
1292 | return fmod (now, 3600.) + 3600.; |
979 | } |
1293 | } |
980 | |
1294 | |
981 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1295 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
982 | |
1296 | |
983 | Example: call a callback every hour, starting now: |
1297 | Example: Call a callback every hour, starting now: |
984 | |
1298 | |
985 | struct ev_periodic hourly_tick; |
1299 | struct ev_periodic hourly_tick; |
986 | ev_periodic_init (&hourly_tick, clock_cb, |
1300 | ev_periodic_init (&hourly_tick, clock_cb, |
987 | fmod (ev_now (loop), 3600.), 3600., 0); |
1301 | fmod (ev_now (loop), 3600.), 3600., 0); |
988 | ev_periodic_start (loop, &hourly_tick); |
1302 | ev_periodic_start (loop, &hourly_tick); |
989 | |
1303 | |
990 | |
1304 | |
991 | =head2 C<ev_signal> - signal me when a signal gets signalled |
1305 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
992 | |
1306 | |
993 | Signal watchers will trigger an event when the process receives a specific |
1307 | Signal watchers will trigger an event when the process receives a specific |
994 | signal one or more times. Even though signals are very asynchronous, libev |
1308 | signal one or more times. Even though signals are very asynchronous, libev |
995 | will try it's best to deliver signals synchronously, i.e. as part of the |
1309 | will try it's best to deliver signals synchronously, i.e. as part of the |
996 | normal event processing, like any other event. |
1310 | normal event processing, like any other event. |
… | |
… | |
1000 | with the kernel (thus it coexists with your own signal handlers as long |
1314 | with the kernel (thus it coexists with your own signal handlers as long |
1001 | as you don't register any with libev). Similarly, when the last signal |
1315 | as you don't register any with libev). Similarly, when the last signal |
1002 | watcher for a signal is stopped libev will reset the signal handler to |
1316 | watcher for a signal is stopped libev will reset the signal handler to |
1003 | SIG_DFL (regardless of what it was set to before). |
1317 | SIG_DFL (regardless of what it was set to before). |
1004 | |
1318 | |
|
|
1319 | =head3 Watcher-Specific Functions and Data Members |
|
|
1320 | |
1005 | =over 4 |
1321 | =over 4 |
1006 | |
1322 | |
1007 | =item ev_signal_init (ev_signal *, callback, int signum) |
1323 | =item ev_signal_init (ev_signal *, callback, int signum) |
1008 | |
1324 | |
1009 | =item ev_signal_set (ev_signal *, int signum) |
1325 | =item ev_signal_set (ev_signal *, int signum) |
1010 | |
1326 | |
1011 | Configures the watcher to trigger on the given signal number (usually one |
1327 | Configures the watcher to trigger on the given signal number (usually one |
1012 | of the C<SIGxxx> constants). |
1328 | of the C<SIGxxx> constants). |
1013 | |
1329 | |
|
|
1330 | =item int signum [read-only] |
|
|
1331 | |
|
|
1332 | The signal the watcher watches out for. |
|
|
1333 | |
1014 | =back |
1334 | =back |
1015 | |
1335 | |
1016 | |
1336 | |
1017 | =head2 C<ev_child> - wait for pid status changes |
1337 | =head2 C<ev_child> - watch out for process status changes |
1018 | |
1338 | |
1019 | Child watchers trigger when your process receives a SIGCHLD in response to |
1339 | Child watchers trigger when your process receives a SIGCHLD in response to |
1020 | some child status changes (most typically when a child of yours dies). |
1340 | some child status changes (most typically when a child of yours dies). |
|
|
1341 | |
|
|
1342 | =head3 Watcher-Specific Functions and Data Members |
1021 | |
1343 | |
1022 | =over 4 |
1344 | =over 4 |
1023 | |
1345 | |
1024 | =item ev_child_init (ev_child *, callback, int pid) |
1346 | =item ev_child_init (ev_child *, callback, int pid) |
1025 | |
1347 | |
… | |
… | |
1030 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
1352 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
1031 | the status word (use the macros from C<sys/wait.h> and see your systems |
1353 | the status word (use the macros from C<sys/wait.h> and see your systems |
1032 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
1354 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
1033 | process causing the status change. |
1355 | process causing the status change. |
1034 | |
1356 | |
|
|
1357 | =item int pid [read-only] |
|
|
1358 | |
|
|
1359 | The process id this watcher watches out for, or C<0>, meaning any process id. |
|
|
1360 | |
|
|
1361 | =item int rpid [read-write] |
|
|
1362 | |
|
|
1363 | The process id that detected a status change. |
|
|
1364 | |
|
|
1365 | =item int rstatus [read-write] |
|
|
1366 | |
|
|
1367 | The process exit/trace status caused by C<rpid> (see your systems |
|
|
1368 | C<waitpid> and C<sys/wait.h> documentation for details). |
|
|
1369 | |
1035 | =back |
1370 | =back |
1036 | |
1371 | |
1037 | Example: try to exit cleanly on SIGINT and SIGTERM. |
1372 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
1038 | |
1373 | |
1039 | static void |
1374 | static void |
1040 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1375 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1041 | { |
1376 | { |
1042 | ev_unloop (loop, EVUNLOOP_ALL); |
1377 | ev_unloop (loop, EVUNLOOP_ALL); |
… | |
… | |
1045 | struct ev_signal signal_watcher; |
1380 | struct ev_signal signal_watcher; |
1046 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1381 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1047 | ev_signal_start (loop, &sigint_cb); |
1382 | ev_signal_start (loop, &sigint_cb); |
1048 | |
1383 | |
1049 | |
1384 | |
|
|
1385 | =head2 C<ev_stat> - did the file attributes just change? |
|
|
1386 | |
|
|
1387 | This watches a filesystem path for attribute changes. That is, it calls |
|
|
1388 | C<stat> regularly (or when the OS says it changed) and sees if it changed |
|
|
1389 | compared to the last time, invoking the callback if it did. |
|
|
1390 | |
|
|
1391 | The path does not need to exist: changing from "path exists" to "path does |
|
|
1392 | not exist" is a status change like any other. The condition "path does |
|
|
1393 | not exist" is signified by the C<st_nlink> field being zero (which is |
|
|
1394 | otherwise always forced to be at least one) and all the other fields of |
|
|
1395 | the stat buffer having unspecified contents. |
|
|
1396 | |
|
|
1397 | The path I<should> be absolute and I<must not> end in a slash. If it is |
|
|
1398 | relative and your working directory changes, the behaviour is undefined. |
|
|
1399 | |
|
|
1400 | Since there is no standard to do this, the portable implementation simply |
|
|
1401 | calls C<stat (2)> regularly on the path to see if it changed somehow. You |
|
|
1402 | can specify a recommended polling interval for this case. If you specify |
|
|
1403 | a polling interval of C<0> (highly recommended!) then a I<suitable, |
|
|
1404 | unspecified default> value will be used (which you can expect to be around |
|
|
1405 | five seconds, although this might change dynamically). Libev will also |
|
|
1406 | impose a minimum interval which is currently around C<0.1>, but thats |
|
|
1407 | usually overkill. |
|
|
1408 | |
|
|
1409 | This watcher type is not meant for massive numbers of stat watchers, |
|
|
1410 | as even with OS-supported change notifications, this can be |
|
|
1411 | resource-intensive. |
|
|
1412 | |
|
|
1413 | At the time of this writing, only the Linux inotify interface is |
|
|
1414 | implemented (implementing kqueue support is left as an exercise for the |
|
|
1415 | reader). Inotify will be used to give hints only and should not change the |
|
|
1416 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
|
|
1417 | to fall back to regular polling again even with inotify, but changes are |
|
|
1418 | usually detected immediately, and if the file exists there will be no |
|
|
1419 | polling. |
|
|
1420 | |
|
|
1421 | =head3 Watcher-Specific Functions and Data Members |
|
|
1422 | |
|
|
1423 | =over 4 |
|
|
1424 | |
|
|
1425 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
|
|
1426 | |
|
|
1427 | =item ev_stat_set (ev_stat *, const char *path, ev_tstamp interval) |
|
|
1428 | |
|
|
1429 | Configures the watcher to wait for status changes of the given |
|
|
1430 | C<path>. The C<interval> is a hint on how quickly a change is expected to |
|
|
1431 | be detected and should normally be specified as C<0> to let libev choose |
|
|
1432 | a suitable value. The memory pointed to by C<path> must point to the same |
|
|
1433 | path for as long as the watcher is active. |
|
|
1434 | |
|
|
1435 | The callback will be receive C<EV_STAT> when a change was detected, |
|
|
1436 | relative to the attributes at the time the watcher was started (or the |
|
|
1437 | last change was detected). |
|
|
1438 | |
|
|
1439 | =item ev_stat_stat (ev_stat *) |
|
|
1440 | |
|
|
1441 | Updates the stat buffer immediately with new values. If you change the |
|
|
1442 | watched path in your callback, you could call this fucntion to avoid |
|
|
1443 | detecting this change (while introducing a race condition). Can also be |
|
|
1444 | useful simply to find out the new values. |
|
|
1445 | |
|
|
1446 | =item ev_statdata attr [read-only] |
|
|
1447 | |
|
|
1448 | The most-recently detected attributes of the file. Although the type is of |
|
|
1449 | C<ev_statdata>, this is usually the (or one of the) C<struct stat> types |
|
|
1450 | suitable for your system. If the C<st_nlink> member is C<0>, then there |
|
|
1451 | was some error while C<stat>ing the file. |
|
|
1452 | |
|
|
1453 | =item ev_statdata prev [read-only] |
|
|
1454 | |
|
|
1455 | The previous attributes of the file. The callback gets invoked whenever |
|
|
1456 | C<prev> != C<attr>. |
|
|
1457 | |
|
|
1458 | =item ev_tstamp interval [read-only] |
|
|
1459 | |
|
|
1460 | The specified interval. |
|
|
1461 | |
|
|
1462 | =item const char *path [read-only] |
|
|
1463 | |
|
|
1464 | The filesystem path that is being watched. |
|
|
1465 | |
|
|
1466 | =back |
|
|
1467 | |
|
|
1468 | Example: Watch C</etc/passwd> for attribute changes. |
|
|
1469 | |
|
|
1470 | static void |
|
|
1471 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
|
|
1472 | { |
|
|
1473 | /* /etc/passwd changed in some way */ |
|
|
1474 | if (w->attr.st_nlink) |
|
|
1475 | { |
|
|
1476 | printf ("passwd current size %ld\n", (long)w->attr.st_size); |
|
|
1477 | printf ("passwd current atime %ld\n", (long)w->attr.st_mtime); |
|
|
1478 | printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime); |
|
|
1479 | } |
|
|
1480 | else |
|
|
1481 | /* you shalt not abuse printf for puts */ |
|
|
1482 | puts ("wow, /etc/passwd is not there, expect problems. " |
|
|
1483 | "if this is windows, they already arrived\n"); |
|
|
1484 | } |
|
|
1485 | |
|
|
1486 | ... |
|
|
1487 | ev_stat passwd; |
|
|
1488 | |
|
|
1489 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd"); |
|
|
1490 | ev_stat_start (loop, &passwd); |
|
|
1491 | |
|
|
1492 | |
1050 | =head2 C<ev_idle> - when you've got nothing better to do |
1493 | =head2 C<ev_idle> - when you've got nothing better to do... |
1051 | |
1494 | |
1052 | Idle watchers trigger events when there are no other events are pending |
1495 | Idle watchers trigger events when no other events of the same or higher |
1053 | (prepare, check and other idle watchers do not count). That is, as long |
1496 | priority are pending (prepare, check and other idle watchers do not |
1054 | as your process is busy handling sockets or timeouts (or even signals, |
1497 | count). |
1055 | imagine) it will not be triggered. But when your process is idle all idle |
1498 | |
1056 | watchers are being called again and again, once per event loop iteration - |
1499 | That is, as long as your process is busy handling sockets or timeouts |
|
|
1500 | (or even signals, imagine) of the same or higher priority it will not be |
|
|
1501 | triggered. But when your process is idle (or only lower-priority watchers |
|
|
1502 | are pending), the idle watchers are being called once per event loop |
1057 | until stopped, that is, or your process receives more events and becomes |
1503 | iteration - until stopped, that is, or your process receives more events |
1058 | busy. |
1504 | and becomes busy again with higher priority stuff. |
1059 | |
1505 | |
1060 | The most noteworthy effect is that as long as any idle watchers are |
1506 | The most noteworthy effect is that as long as any idle watchers are |
1061 | active, the process will not block when waiting for new events. |
1507 | active, the process will not block when waiting for new events. |
1062 | |
1508 | |
1063 | Apart from keeping your process non-blocking (which is a useful |
1509 | Apart from keeping your process non-blocking (which is a useful |
1064 | effect on its own sometimes), idle watchers are a good place to do |
1510 | effect on its own sometimes), idle watchers are a good place to do |
1065 | "pseudo-background processing", or delay processing stuff to after the |
1511 | "pseudo-background processing", or delay processing stuff to after the |
1066 | event loop has handled all outstanding events. |
1512 | event loop has handled all outstanding events. |
1067 | |
1513 | |
|
|
1514 | =head3 Watcher-Specific Functions and Data Members |
|
|
1515 | |
1068 | =over 4 |
1516 | =over 4 |
1069 | |
1517 | |
1070 | =item ev_idle_init (ev_signal *, callback) |
1518 | =item ev_idle_init (ev_signal *, callback) |
1071 | |
1519 | |
1072 | Initialises and configures the idle watcher - it has no parameters of any |
1520 | Initialises and configures the idle watcher - it has no parameters of any |
1073 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1521 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1074 | believe me. |
1522 | believe me. |
1075 | |
1523 | |
1076 | =back |
1524 | =back |
1077 | |
1525 | |
1078 | Example: dynamically allocate an C<ev_idle>, start it, and in the |
1526 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1079 | callback, free it. Alos, use no error checking, as usual. |
1527 | callback, free it. Also, use no error checking, as usual. |
1080 | |
1528 | |
1081 | static void |
1529 | static void |
1082 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1530 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1083 | { |
1531 | { |
1084 | free (w); |
1532 | free (w); |
… | |
… | |
1089 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1537 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1090 | ev_idle_init (idle_watcher, idle_cb); |
1538 | ev_idle_init (idle_watcher, idle_cb); |
1091 | ev_idle_start (loop, idle_cb); |
1539 | ev_idle_start (loop, idle_cb); |
1092 | |
1540 | |
1093 | |
1541 | |
1094 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop |
1542 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
1095 | |
1543 | |
1096 | Prepare and check watchers are usually (but not always) used in tandem: |
1544 | Prepare and check watchers are usually (but not always) used in tandem: |
1097 | prepare watchers get invoked before the process blocks and check watchers |
1545 | prepare watchers get invoked before the process blocks and check watchers |
1098 | afterwards. |
1546 | afterwards. |
1099 | |
1547 | |
|
|
1548 | You I<must not> call C<ev_loop> or similar functions that enter |
|
|
1549 | the current event loop from either C<ev_prepare> or C<ev_check> |
|
|
1550 | watchers. Other loops than the current one are fine, however. The |
|
|
1551 | rationale behind this is that you do not need to check for recursion in |
|
|
1552 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
|
|
1553 | C<ev_check> so if you have one watcher of each kind they will always be |
|
|
1554 | called in pairs bracketing the blocking call. |
|
|
1555 | |
1100 | Their main purpose is to integrate other event mechanisms into libev and |
1556 | Their main purpose is to integrate other event mechanisms into libev and |
1101 | their use is somewhat advanced. This could be used, for example, to track |
1557 | their use is somewhat advanced. This could be used, for example, to track |
1102 | variable changes, implement your own watchers, integrate net-snmp or a |
1558 | variable changes, implement your own watchers, integrate net-snmp or a |
1103 | coroutine library and lots more. |
1559 | coroutine library and lots more. They are also occasionally useful if |
|
|
1560 | you cache some data and want to flush it before blocking (for example, |
|
|
1561 | in X programs you might want to do an C<XFlush ()> in an C<ev_prepare> |
|
|
1562 | watcher). |
1104 | |
1563 | |
1105 | This is done by examining in each prepare call which file descriptors need |
1564 | This is done by examining in each prepare call which file descriptors need |
1106 | to be watched by the other library, registering C<ev_io> watchers for |
1565 | to be watched by the other library, registering C<ev_io> watchers for |
1107 | them and starting an C<ev_timer> watcher for any timeouts (many libraries |
1566 | them and starting an C<ev_timer> watcher for any timeouts (many libraries |
1108 | provide just this functionality). Then, in the check watcher you check for |
1567 | provide just this functionality). Then, in the check watcher you check for |
… | |
… | |
1118 | with priority higher than or equal to the event loop and one coroutine |
1577 | with priority higher than or equal to the event loop and one coroutine |
1119 | of lower priority, but only once, using idle watchers to keep the event |
1578 | of lower priority, but only once, using idle watchers to keep the event |
1120 | loop from blocking if lower-priority coroutines are active, thus mapping |
1579 | loop from blocking if lower-priority coroutines are active, thus mapping |
1121 | low-priority coroutines to idle/background tasks). |
1580 | low-priority coroutines to idle/background tasks). |
1122 | |
1581 | |
|
|
1582 | It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>) |
|
|
1583 | priority, to ensure that they are being run before any other watchers |
|
|
1584 | after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers, |
|
|
1585 | too) should not activate ("feed") events into libev. While libev fully |
|
|
1586 | supports this, they will be called before other C<ev_check> watchers did |
|
|
1587 | their job. As C<ev_check> watchers are often used to embed other event |
|
|
1588 | loops those other event loops might be in an unusable state until their |
|
|
1589 | C<ev_check> watcher ran (always remind yourself to coexist peacefully with |
|
|
1590 | others). |
|
|
1591 | |
|
|
1592 | =head3 Watcher-Specific Functions and Data Members |
|
|
1593 | |
1123 | =over 4 |
1594 | =over 4 |
1124 | |
1595 | |
1125 | =item ev_prepare_init (ev_prepare *, callback) |
1596 | =item ev_prepare_init (ev_prepare *, callback) |
1126 | |
1597 | |
1127 | =item ev_check_init (ev_check *, callback) |
1598 | =item ev_check_init (ev_check *, callback) |
… | |
… | |
1130 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1601 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1131 | macros, but using them is utterly, utterly and completely pointless. |
1602 | macros, but using them is utterly, utterly and completely pointless. |
1132 | |
1603 | |
1133 | =back |
1604 | =back |
1134 | |
1605 | |
1135 | Example: *TODO*. |
1606 | There are a number of principal ways to embed other event loops or modules |
|
|
1607 | into libev. Here are some ideas on how to include libadns into libev |
|
|
1608 | (there is a Perl module named C<EV::ADNS> that does this, which you could |
|
|
1609 | use for an actually working example. Another Perl module named C<EV::Glib> |
|
|
1610 | embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV |
|
|
1611 | into the Glib event loop). |
1136 | |
1612 | |
|
|
1613 | Method 1: Add IO watchers and a timeout watcher in a prepare handler, |
|
|
1614 | and in a check watcher, destroy them and call into libadns. What follows |
|
|
1615 | is pseudo-code only of course. This requires you to either use a low |
|
|
1616 | priority for the check watcher or use C<ev_clear_pending> explicitly, as |
|
|
1617 | the callbacks for the IO/timeout watchers might not have been called yet. |
1137 | |
1618 | |
|
|
1619 | static ev_io iow [nfd]; |
|
|
1620 | static ev_timer tw; |
|
|
1621 | |
|
|
1622 | static void |
|
|
1623 | io_cb (ev_loop *loop, ev_io *w, int revents) |
|
|
1624 | { |
|
|
1625 | } |
|
|
1626 | |
|
|
1627 | // create io watchers for each fd and a timer before blocking |
|
|
1628 | static void |
|
|
1629 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
|
|
1630 | { |
|
|
1631 | int timeout = 3600000; |
|
|
1632 | struct pollfd fds [nfd]; |
|
|
1633 | // actual code will need to loop here and realloc etc. |
|
|
1634 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
|
|
1635 | |
|
|
1636 | /* the callback is illegal, but won't be called as we stop during check */ |
|
|
1637 | ev_timer_init (&tw, 0, timeout * 1e-3); |
|
|
1638 | ev_timer_start (loop, &tw); |
|
|
1639 | |
|
|
1640 | // create one ev_io per pollfd |
|
|
1641 | for (int i = 0; i < nfd; ++i) |
|
|
1642 | { |
|
|
1643 | ev_io_init (iow + i, io_cb, fds [i].fd, |
|
|
1644 | ((fds [i].events & POLLIN ? EV_READ : 0) |
|
|
1645 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
|
|
1646 | |
|
|
1647 | fds [i].revents = 0; |
|
|
1648 | ev_io_start (loop, iow + i); |
|
|
1649 | } |
|
|
1650 | } |
|
|
1651 | |
|
|
1652 | // stop all watchers after blocking |
|
|
1653 | static void |
|
|
1654 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
|
|
1655 | { |
|
|
1656 | ev_timer_stop (loop, &tw); |
|
|
1657 | |
|
|
1658 | for (int i = 0; i < nfd; ++i) |
|
|
1659 | { |
|
|
1660 | // set the relevant poll flags |
|
|
1661 | // could also call adns_processreadable etc. here |
|
|
1662 | struct pollfd *fd = fds + i; |
|
|
1663 | int revents = ev_clear_pending (iow + i); |
|
|
1664 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1665 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1666 | |
|
|
1667 | // now stop the watcher |
|
|
1668 | ev_io_stop (loop, iow + i); |
|
|
1669 | } |
|
|
1670 | |
|
|
1671 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
1672 | } |
|
|
1673 | |
|
|
1674 | Method 2: This would be just like method 1, but you run C<adns_afterpoll> |
|
|
1675 | in the prepare watcher and would dispose of the check watcher. |
|
|
1676 | |
|
|
1677 | Method 3: If the module to be embedded supports explicit event |
|
|
1678 | notification (adns does), you can also make use of the actual watcher |
|
|
1679 | callbacks, and only destroy/create the watchers in the prepare watcher. |
|
|
1680 | |
|
|
1681 | static void |
|
|
1682 | timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1683 | { |
|
|
1684 | adns_state ads = (adns_state)w->data; |
|
|
1685 | update_now (EV_A); |
|
|
1686 | |
|
|
1687 | adns_processtimeouts (ads, &tv_now); |
|
|
1688 | } |
|
|
1689 | |
|
|
1690 | static void |
|
|
1691 | io_cb (EV_P_ ev_io *w, int revents) |
|
|
1692 | { |
|
|
1693 | adns_state ads = (adns_state)w->data; |
|
|
1694 | update_now (EV_A); |
|
|
1695 | |
|
|
1696 | if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now); |
|
|
1697 | if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now); |
|
|
1698 | } |
|
|
1699 | |
|
|
1700 | // do not ever call adns_afterpoll |
|
|
1701 | |
|
|
1702 | Method 4: Do not use a prepare or check watcher because the module you |
|
|
1703 | want to embed is too inflexible to support it. Instead, youc na override |
|
|
1704 | their poll function. The drawback with this solution is that the main |
|
|
1705 | loop is now no longer controllable by EV. The C<Glib::EV> module does |
|
|
1706 | this. |
|
|
1707 | |
|
|
1708 | static gint |
|
|
1709 | event_poll_func (GPollFD *fds, guint nfds, gint timeout) |
|
|
1710 | { |
|
|
1711 | int got_events = 0; |
|
|
1712 | |
|
|
1713 | for (n = 0; n < nfds; ++n) |
|
|
1714 | // create/start io watcher that sets the relevant bits in fds[n] and increment got_events |
|
|
1715 | |
|
|
1716 | if (timeout >= 0) |
|
|
1717 | // create/start timer |
|
|
1718 | |
|
|
1719 | // poll |
|
|
1720 | ev_loop (EV_A_ 0); |
|
|
1721 | |
|
|
1722 | // stop timer again |
|
|
1723 | if (timeout >= 0) |
|
|
1724 | ev_timer_stop (EV_A_ &to); |
|
|
1725 | |
|
|
1726 | // stop io watchers again - their callbacks should have set |
|
|
1727 | for (n = 0; n < nfds; ++n) |
|
|
1728 | ev_io_stop (EV_A_ iow [n]); |
|
|
1729 | |
|
|
1730 | return got_events; |
|
|
1731 | } |
|
|
1732 | |
|
|
1733 | |
1138 | =head2 C<ev_embed> - when one backend isn't enough |
1734 | =head2 C<ev_embed> - when one backend isn't enough... |
1139 | |
1735 | |
1140 | This is a rather advanced watcher type that lets you embed one event loop |
1736 | This is a rather advanced watcher type that lets you embed one event loop |
1141 | into another (currently only C<ev_io> events are supported in the embedded |
1737 | into another (currently only C<ev_io> events are supported in the embedded |
1142 | loop, other types of watchers might be handled in a delayed or incorrect |
1738 | loop, other types of watchers might be handled in a delayed or incorrect |
1143 | fashion and must not be used). |
1739 | fashion and must not be used). (See portability notes, below). |
1144 | |
1740 | |
1145 | There are primarily two reasons you would want that: work around bugs and |
1741 | There are primarily two reasons you would want that: work around bugs and |
1146 | prioritise I/O. |
1742 | prioritise I/O. |
1147 | |
1743 | |
1148 | As an example for a bug workaround, the kqueue backend might only support |
1744 | As an example for a bug workaround, the kqueue backend might only support |
… | |
… | |
1203 | ev_embed_start (loop_hi, &embed); |
1799 | ev_embed_start (loop_hi, &embed); |
1204 | } |
1800 | } |
1205 | else |
1801 | else |
1206 | loop_lo = loop_hi; |
1802 | loop_lo = loop_hi; |
1207 | |
1803 | |
|
|
1804 | =head2 Portability notes |
|
|
1805 | |
|
|
1806 | Kqueue is nominally embeddable, but this is broken on all BSDs that I |
|
|
1807 | tried, in various ways. Usually the embedded event loop will simply never |
|
|
1808 | receive events, sometimes it will only trigger a few times, sometimes in a |
|
|
1809 | loop. Epoll is also nominally embeddable, but many Linux kernel versions |
|
|
1810 | will always eport the epoll fd as ready, even when no events are pending. |
|
|
1811 | |
|
|
1812 | While libev allows embedding these backends (they are contained in |
|
|
1813 | C<ev_embeddable_backends ()>), take extreme care that it will actually |
|
|
1814 | work. |
|
|
1815 | |
|
|
1816 | When in doubt, create a dynamic event loop forced to use sockets (this |
|
|
1817 | usually works) and possibly another thread and a pipe or so to report to |
|
|
1818 | your main event loop. |
|
|
1819 | |
|
|
1820 | =head3 Watcher-Specific Functions and Data Members |
|
|
1821 | |
1208 | =over 4 |
1822 | =over 4 |
1209 | |
1823 | |
1210 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
1824 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
1211 | |
1825 | |
1212 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
1826 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
… | |
… | |
1221 | |
1835 | |
1222 | Make a single, non-blocking sweep over the embedded loop. This works |
1836 | Make a single, non-blocking sweep over the embedded loop. This works |
1223 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
1837 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
1224 | apropriate way for embedded loops. |
1838 | apropriate way for embedded loops. |
1225 | |
1839 | |
|
|
1840 | =item struct ev_loop *other [read-only] |
|
|
1841 | |
|
|
1842 | The embedded event loop. |
|
|
1843 | |
|
|
1844 | =back |
|
|
1845 | |
|
|
1846 | |
|
|
1847 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
|
|
1848 | |
|
|
1849 | Fork watchers are called when a C<fork ()> was detected (usually because |
|
|
1850 | whoever is a good citizen cared to tell libev about it by calling |
|
|
1851 | C<ev_default_fork> or C<ev_loop_fork>). The invocation is done before the |
|
|
1852 | event loop blocks next and before C<ev_check> watchers are being called, |
|
|
1853 | and only in the child after the fork. If whoever good citizen calling |
|
|
1854 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
|
|
1855 | handlers will be invoked, too, of course. |
|
|
1856 | |
|
|
1857 | =head3 Watcher-Specific Functions and Data Members |
|
|
1858 | |
|
|
1859 | =over 4 |
|
|
1860 | |
|
|
1861 | =item ev_fork_init (ev_signal *, callback) |
|
|
1862 | |
|
|
1863 | Initialises and configures the fork watcher - it has no parameters of any |
|
|
1864 | kind. There is a C<ev_fork_set> macro, but using it is utterly pointless, |
|
|
1865 | believe me. |
|
|
1866 | |
1226 | =back |
1867 | =back |
1227 | |
1868 | |
1228 | |
1869 | |
1229 | =head1 OTHER FUNCTIONS |
1870 | =head1 OTHER FUNCTIONS |
1230 | |
1871 | |
… | |
… | |
1318 | |
1959 | |
1319 | To use it, |
1960 | To use it, |
1320 | |
1961 | |
1321 | #include <ev++.h> |
1962 | #include <ev++.h> |
1322 | |
1963 | |
1323 | (it is not installed by default). This automatically includes F<ev.h> |
1964 | This automatically includes F<ev.h> and puts all of its definitions (many |
1324 | and puts all of its definitions (many of them macros) into the global |
1965 | of them macros) into the global namespace. All C++ specific things are |
1325 | namespace. All C++ specific things are put into the C<ev> namespace. |
1966 | put into the C<ev> namespace. It should support all the same embedding |
|
|
1967 | options as F<ev.h>, most notably C<EV_MULTIPLICITY>. |
1326 | |
1968 | |
1327 | It should support all the same embedding options as F<ev.h>, most notably |
1969 | Care has been taken to keep the overhead low. The only data member the C++ |
1328 | C<EV_MULTIPLICITY>. |
1970 | classes add (compared to plain C-style watchers) is the event loop pointer |
|
|
1971 | that the watcher is associated with (or no additional members at all if |
|
|
1972 | you disable C<EV_MULTIPLICITY> when embedding libev). |
|
|
1973 | |
|
|
1974 | Currently, functions, and static and non-static member functions can be |
|
|
1975 | used as callbacks. Other types should be easy to add as long as they only |
|
|
1976 | need one additional pointer for context. If you need support for other |
|
|
1977 | types of functors please contact the author (preferably after implementing |
|
|
1978 | it). |
1329 | |
1979 | |
1330 | Here is a list of things available in the C<ev> namespace: |
1980 | Here is a list of things available in the C<ev> namespace: |
1331 | |
1981 | |
1332 | =over 4 |
1982 | =over 4 |
1333 | |
1983 | |
… | |
… | |
1349 | |
1999 | |
1350 | All of those classes have these methods: |
2000 | All of those classes have these methods: |
1351 | |
2001 | |
1352 | =over 4 |
2002 | =over 4 |
1353 | |
2003 | |
1354 | =item ev::TYPE::TYPE (object *, object::method *) |
2004 | =item ev::TYPE::TYPE () |
1355 | |
2005 | |
1356 | =item ev::TYPE::TYPE (object *, object::method *, struct ev_loop *) |
2006 | =item ev::TYPE::TYPE (struct ev_loop *) |
1357 | |
2007 | |
1358 | =item ev::TYPE::~TYPE |
2008 | =item ev::TYPE::~TYPE |
1359 | |
2009 | |
1360 | The constructor takes a pointer to an object and a method pointer to |
2010 | The constructor (optionally) takes an event loop to associate the watcher |
1361 | the event handler callback to call in this class. The constructor calls |
2011 | with. If it is omitted, it will use C<EV_DEFAULT>. |
1362 | C<ev_init> for you, which means you have to call the C<set> method |
2012 | |
1363 | before starting it. If you do not specify a loop then the constructor |
2013 | The constructor calls C<ev_init> for you, which means you have to call the |
1364 | automatically associates the default loop with this watcher. |
2014 | C<set> method before starting it. |
|
|
2015 | |
|
|
2016 | It will not set a callback, however: You have to call the templated C<set> |
|
|
2017 | method to set a callback before you can start the watcher. |
|
|
2018 | |
|
|
2019 | (The reason why you have to use a method is a limitation in C++ which does |
|
|
2020 | not allow explicit template arguments for constructors). |
1365 | |
2021 | |
1366 | The destructor automatically stops the watcher if it is active. |
2022 | The destructor automatically stops the watcher if it is active. |
|
|
2023 | |
|
|
2024 | =item w->set<class, &class::method> (object *) |
|
|
2025 | |
|
|
2026 | This method sets the callback method to call. The method has to have a |
|
|
2027 | signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as |
|
|
2028 | first argument and the C<revents> as second. The object must be given as |
|
|
2029 | parameter and is stored in the C<data> member of the watcher. |
|
|
2030 | |
|
|
2031 | This method synthesizes efficient thunking code to call your method from |
|
|
2032 | the C callback that libev requires. If your compiler can inline your |
|
|
2033 | callback (i.e. it is visible to it at the place of the C<set> call and |
|
|
2034 | your compiler is good :), then the method will be fully inlined into the |
|
|
2035 | thunking function, making it as fast as a direct C callback. |
|
|
2036 | |
|
|
2037 | Example: simple class declaration and watcher initialisation |
|
|
2038 | |
|
|
2039 | struct myclass |
|
|
2040 | { |
|
|
2041 | void io_cb (ev::io &w, int revents) { } |
|
|
2042 | } |
|
|
2043 | |
|
|
2044 | myclass obj; |
|
|
2045 | ev::io iow; |
|
|
2046 | iow.set <myclass, &myclass::io_cb> (&obj); |
|
|
2047 | |
|
|
2048 | =item w->set<function> (void *data = 0) |
|
|
2049 | |
|
|
2050 | Also sets a callback, but uses a static method or plain function as |
|
|
2051 | callback. The optional C<data> argument will be stored in the watcher's |
|
|
2052 | C<data> member and is free for you to use. |
|
|
2053 | |
|
|
2054 | The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>. |
|
|
2055 | |
|
|
2056 | See the method-C<set> above for more details. |
|
|
2057 | |
|
|
2058 | Example: |
|
|
2059 | |
|
|
2060 | static void io_cb (ev::io &w, int revents) { } |
|
|
2061 | iow.set <io_cb> (); |
1367 | |
2062 | |
1368 | =item w->set (struct ev_loop *) |
2063 | =item w->set (struct ev_loop *) |
1369 | |
2064 | |
1370 | Associates a different C<struct ev_loop> with this watcher. You can only |
2065 | Associates a different C<struct ev_loop> with this watcher. You can only |
1371 | do this when the watcher is inactive (and not pending either). |
2066 | do this when the watcher is inactive (and not pending either). |
1372 | |
2067 | |
1373 | =item w->set ([args]) |
2068 | =item w->set ([args]) |
1374 | |
2069 | |
1375 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
2070 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
1376 | called at least once. Unlike the C counterpart, an active watcher gets |
2071 | called at least once. Unlike the C counterpart, an active watcher gets |
1377 | automatically stopped and restarted. |
2072 | automatically stopped and restarted when reconfiguring it with this |
|
|
2073 | method. |
1378 | |
2074 | |
1379 | =item w->start () |
2075 | =item w->start () |
1380 | |
2076 | |
1381 | Starts the watcher. Note that there is no C<loop> argument as the |
2077 | Starts the watcher. Note that there is no C<loop> argument, as the |
1382 | constructor already takes the loop. |
2078 | constructor already stores the event loop. |
1383 | |
2079 | |
1384 | =item w->stop () |
2080 | =item w->stop () |
1385 | |
2081 | |
1386 | Stops the watcher if it is active. Again, no C<loop> argument. |
2082 | Stops the watcher if it is active. Again, no C<loop> argument. |
1387 | |
2083 | |
1388 | =item w->again () C<ev::timer>, C<ev::periodic> only |
2084 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
1389 | |
2085 | |
1390 | For C<ev::timer> and C<ev::periodic>, this invokes the corresponding |
2086 | For C<ev::timer> and C<ev::periodic>, this invokes the corresponding |
1391 | C<ev_TYPE_again> function. |
2087 | C<ev_TYPE_again> function. |
1392 | |
2088 | |
1393 | =item w->sweep () C<ev::embed> only |
2089 | =item w->sweep () (C<ev::embed> only) |
1394 | |
2090 | |
1395 | Invokes C<ev_embed_sweep>. |
2091 | Invokes C<ev_embed_sweep>. |
|
|
2092 | |
|
|
2093 | =item w->update () (C<ev::stat> only) |
|
|
2094 | |
|
|
2095 | Invokes C<ev_stat_stat>. |
1396 | |
2096 | |
1397 | =back |
2097 | =back |
1398 | |
2098 | |
1399 | =back |
2099 | =back |
1400 | |
2100 | |
… | |
… | |
1408 | |
2108 | |
1409 | myclass (); |
2109 | myclass (); |
1410 | } |
2110 | } |
1411 | |
2111 | |
1412 | myclass::myclass (int fd) |
2112 | myclass::myclass (int fd) |
1413 | : io (this, &myclass::io_cb), |
|
|
1414 | idle (this, &myclass::idle_cb) |
|
|
1415 | { |
2113 | { |
|
|
2114 | io .set <myclass, &myclass::io_cb > (this); |
|
|
2115 | idle.set <myclass, &myclass::idle_cb> (this); |
|
|
2116 | |
1416 | io.start (fd, ev::READ); |
2117 | io.start (fd, ev::READ); |
1417 | } |
2118 | } |
|
|
2119 | |
|
|
2120 | |
|
|
2121 | =head1 MACRO MAGIC |
|
|
2122 | |
|
|
2123 | Libev can be compiled with a variety of options, the most fundamantal |
|
|
2124 | of which is C<EV_MULTIPLICITY>. This option determines whether (most) |
|
|
2125 | functions and callbacks have an initial C<struct ev_loop *> argument. |
|
|
2126 | |
|
|
2127 | To make it easier to write programs that cope with either variant, the |
|
|
2128 | following macros are defined: |
|
|
2129 | |
|
|
2130 | =over 4 |
|
|
2131 | |
|
|
2132 | =item C<EV_A>, C<EV_A_> |
|
|
2133 | |
|
|
2134 | This provides the loop I<argument> for functions, if one is required ("ev |
|
|
2135 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
|
|
2136 | C<EV_A_> is used when other arguments are following. Example: |
|
|
2137 | |
|
|
2138 | ev_unref (EV_A); |
|
|
2139 | ev_timer_add (EV_A_ watcher); |
|
|
2140 | ev_loop (EV_A_ 0); |
|
|
2141 | |
|
|
2142 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
|
|
2143 | which is often provided by the following macro. |
|
|
2144 | |
|
|
2145 | =item C<EV_P>, C<EV_P_> |
|
|
2146 | |
|
|
2147 | This provides the loop I<parameter> for functions, if one is required ("ev |
|
|
2148 | loop parameter"). The C<EV_P> form is used when this is the sole parameter, |
|
|
2149 | C<EV_P_> is used when other parameters are following. Example: |
|
|
2150 | |
|
|
2151 | // this is how ev_unref is being declared |
|
|
2152 | static void ev_unref (EV_P); |
|
|
2153 | |
|
|
2154 | // this is how you can declare your typical callback |
|
|
2155 | static void cb (EV_P_ ev_timer *w, int revents) |
|
|
2156 | |
|
|
2157 | It declares a parameter C<loop> of type C<struct ev_loop *>, quite |
|
|
2158 | suitable for use with C<EV_A>. |
|
|
2159 | |
|
|
2160 | =item C<EV_DEFAULT>, C<EV_DEFAULT_> |
|
|
2161 | |
|
|
2162 | Similar to the other two macros, this gives you the value of the default |
|
|
2163 | loop, if multiple loops are supported ("ev loop default"). |
|
|
2164 | |
|
|
2165 | =back |
|
|
2166 | |
|
|
2167 | Example: Declare and initialise a check watcher, utilising the above |
|
|
2168 | macros so it will work regardless of whether multiple loops are supported |
|
|
2169 | or not. |
|
|
2170 | |
|
|
2171 | static void |
|
|
2172 | check_cb (EV_P_ ev_timer *w, int revents) |
|
|
2173 | { |
|
|
2174 | ev_check_stop (EV_A_ w); |
|
|
2175 | } |
|
|
2176 | |
|
|
2177 | ev_check check; |
|
|
2178 | ev_check_init (&check, check_cb); |
|
|
2179 | ev_check_start (EV_DEFAULT_ &check); |
|
|
2180 | ev_loop (EV_DEFAULT_ 0); |
1418 | |
2181 | |
1419 | =head1 EMBEDDING |
2182 | =head1 EMBEDDING |
1420 | |
2183 | |
1421 | Libev can (and often is) directly embedded into host |
2184 | Libev can (and often is) directly embedded into host |
1422 | applications. Examples of applications that embed it include the Deliantra |
2185 | applications. Examples of applications that embed it include the Deliantra |
1423 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
2186 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
1424 | and rxvt-unicode. |
2187 | and rxvt-unicode. |
1425 | |
2188 | |
1426 | The goal is to enable you to just copy the neecssary files into your |
2189 | The goal is to enable you to just copy the necessary files into your |
1427 | source directory without having to change even a single line in them, so |
2190 | source directory without having to change even a single line in them, so |
1428 | you can easily upgrade by simply copying (or having a checked-out copy of |
2191 | you can easily upgrade by simply copying (or having a checked-out copy of |
1429 | libev somewhere in your source tree). |
2192 | libev somewhere in your source tree). |
1430 | |
2193 | |
1431 | =head2 FILESETS |
2194 | =head2 FILESETS |
… | |
… | |
1462 | ev_vars.h |
2225 | ev_vars.h |
1463 | ev_wrap.h |
2226 | ev_wrap.h |
1464 | |
2227 | |
1465 | ev_win32.c required on win32 platforms only |
2228 | ev_win32.c required on win32 platforms only |
1466 | |
2229 | |
1467 | ev_select.c only when select backend is enabled (which is is by default) |
2230 | ev_select.c only when select backend is enabled (which is enabled by default) |
1468 | ev_poll.c only when poll backend is enabled (disabled by default) |
2231 | ev_poll.c only when poll backend is enabled (disabled by default) |
1469 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
2232 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
1470 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
2233 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
1471 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
2234 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
1472 | |
2235 | |
1473 | F<ev.c> includes the backend files directly when enabled, so you only need |
2236 | F<ev.c> includes the backend files directly when enabled, so you only need |
1474 | to compile a single file. |
2237 | to compile this single file. |
1475 | |
2238 | |
1476 | =head3 LIBEVENT COMPATIBILITY API |
2239 | =head3 LIBEVENT COMPATIBILITY API |
1477 | |
2240 | |
1478 | To include the libevent compatibility API, also include: |
2241 | To include the libevent compatibility API, also include: |
1479 | |
2242 | |
… | |
… | |
1492 | |
2255 | |
1493 | =head3 AUTOCONF SUPPORT |
2256 | =head3 AUTOCONF SUPPORT |
1494 | |
2257 | |
1495 | Instead of using C<EV_STANDALONE=1> and providing your config in |
2258 | Instead of using C<EV_STANDALONE=1> and providing your config in |
1496 | whatever way you want, you can also C<m4_include([libev.m4])> in your |
2259 | whatever way you want, you can also C<m4_include([libev.m4])> in your |
1497 | F<configure.ac> and leave C<EV_STANDALONE> off. F<ev.c> will then include |
2260 | F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then |
1498 | F<config.h> and configure itself accordingly. |
2261 | include F<config.h> and configure itself accordingly. |
1499 | |
2262 | |
1500 | For this of course you need the m4 file: |
2263 | For this of course you need the m4 file: |
1501 | |
2264 | |
1502 | libev.m4 |
2265 | libev.m4 |
1503 | |
2266 | |
… | |
… | |
1521 | |
2284 | |
1522 | If defined to be C<1>, libev will try to detect the availability of the |
2285 | If defined to be C<1>, libev will try to detect the availability of the |
1523 | monotonic clock option at both compiletime and runtime. Otherwise no use |
2286 | monotonic clock option at both compiletime and runtime. Otherwise no use |
1524 | of the monotonic clock option will be attempted. If you enable this, you |
2287 | of the monotonic clock option will be attempted. If you enable this, you |
1525 | usually have to link against librt or something similar. Enabling it when |
2288 | usually have to link against librt or something similar. Enabling it when |
1526 | the functionality isn't available is safe, though, althoguh you have |
2289 | the functionality isn't available is safe, though, although you have |
1527 | to make sure you link against any libraries where the C<clock_gettime> |
2290 | to make sure you link against any libraries where the C<clock_gettime> |
1528 | function is hiding in (often F<-lrt>). |
2291 | function is hiding in (often F<-lrt>). |
1529 | |
2292 | |
1530 | =item EV_USE_REALTIME |
2293 | =item EV_USE_REALTIME |
1531 | |
2294 | |
1532 | If defined to be C<1>, libev will try to detect the availability of the |
2295 | If defined to be C<1>, libev will try to detect the availability of the |
1533 | realtime clock option at compiletime (and assume its availability at |
2296 | realtime clock option at compiletime (and assume its availability at |
1534 | runtime if successful). Otherwise no use of the realtime clock option will |
2297 | runtime if successful). Otherwise no use of the realtime clock option will |
1535 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
2298 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
1536 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries |
2299 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See the |
1537 | in the description of C<EV_USE_MONOTONIC>, though. |
2300 | note about libraries in the description of C<EV_USE_MONOTONIC>, though. |
1538 | |
2301 | |
1539 | =item EV_USE_SELECT |
2302 | =item EV_USE_SELECT |
1540 | |
2303 | |
1541 | If undefined or defined to be C<1>, libev will compile in support for the |
2304 | If undefined or defined to be C<1>, libev will compile in support for the |
1542 | C<select>(2) backend. No attempt at autodetection will be done: if no |
2305 | C<select>(2) backend. No attempt at autodetection will be done: if no |
… | |
… | |
1583 | otherwise another method will be used as fallback. This is the preferred |
2346 | otherwise another method will be used as fallback. This is the preferred |
1584 | backend for BSD and BSD-like systems, although on most BSDs kqueue only |
2347 | backend for BSD and BSD-like systems, although on most BSDs kqueue only |
1585 | supports some types of fds correctly (the only platform we found that |
2348 | supports some types of fds correctly (the only platform we found that |
1586 | supports ptys for example was NetBSD), so kqueue might be compiled in, but |
2349 | supports ptys for example was NetBSD), so kqueue might be compiled in, but |
1587 | not be used unless explicitly requested. The best way to use it is to find |
2350 | not be used unless explicitly requested. The best way to use it is to find |
1588 | out wether kqueue supports your type of fd properly and use an embedded |
2351 | out whether kqueue supports your type of fd properly and use an embedded |
1589 | kqueue loop. |
2352 | kqueue loop. |
1590 | |
2353 | |
1591 | =item EV_USE_PORT |
2354 | =item EV_USE_PORT |
1592 | |
2355 | |
1593 | If defined to be C<1>, libev will compile in support for the Solaris |
2356 | If defined to be C<1>, libev will compile in support for the Solaris |
… | |
… | |
1596 | backend for Solaris 10 systems. |
2359 | backend for Solaris 10 systems. |
1597 | |
2360 | |
1598 | =item EV_USE_DEVPOLL |
2361 | =item EV_USE_DEVPOLL |
1599 | |
2362 | |
1600 | reserved for future expansion, works like the USE symbols above. |
2363 | reserved for future expansion, works like the USE symbols above. |
|
|
2364 | |
|
|
2365 | =item EV_USE_INOTIFY |
|
|
2366 | |
|
|
2367 | If defined to be C<1>, libev will compile in support for the Linux inotify |
|
|
2368 | interface to speed up C<ev_stat> watchers. Its actual availability will |
|
|
2369 | be detected at runtime. |
1601 | |
2370 | |
1602 | =item EV_H |
2371 | =item EV_H |
1603 | |
2372 | |
1604 | The name of the F<ev.h> header file used to include it. The default if |
2373 | The name of the F<ev.h> header file used to include it. The default if |
1605 | undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This |
2374 | undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This |
… | |
… | |
1629 | will have the C<struct ev_loop *> as first argument, and you can create |
2398 | will have the C<struct ev_loop *> as first argument, and you can create |
1630 | additional independent event loops. Otherwise there will be no support |
2399 | additional independent event loops. Otherwise there will be no support |
1631 | for multiple event loops and there is no first event loop pointer |
2400 | for multiple event loops and there is no first event loop pointer |
1632 | argument. Instead, all functions act on the single default loop. |
2401 | argument. Instead, all functions act on the single default loop. |
1633 | |
2402 | |
|
|
2403 | =item EV_MINPRI |
|
|
2404 | |
|
|
2405 | =item EV_MAXPRI |
|
|
2406 | |
|
|
2407 | The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to |
|
|
2408 | C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can |
|
|
2409 | provide for more priorities by overriding those symbols (usually defined |
|
|
2410 | to be C<-2> and C<2>, respectively). |
|
|
2411 | |
|
|
2412 | When doing priority-based operations, libev usually has to linearly search |
|
|
2413 | all the priorities, so having many of them (hundreds) uses a lot of space |
|
|
2414 | and time, so using the defaults of five priorities (-2 .. +2) is usually |
|
|
2415 | fine. |
|
|
2416 | |
|
|
2417 | If your embedding app does not need any priorities, defining these both to |
|
|
2418 | C<0> will save some memory and cpu. |
|
|
2419 | |
1634 | =item EV_PERIODICS |
2420 | =item EV_PERIODIC_ENABLE |
1635 | |
2421 | |
1636 | If undefined or defined to be C<1>, then periodic timers are supported, |
2422 | If undefined or defined to be C<1>, then periodic timers are supported. If |
1637 | otherwise not. This saves a few kb of code. |
2423 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
2424 | code. |
|
|
2425 | |
|
|
2426 | =item EV_IDLE_ENABLE |
|
|
2427 | |
|
|
2428 | If undefined or defined to be C<1>, then idle watchers are supported. If |
|
|
2429 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
2430 | code. |
|
|
2431 | |
|
|
2432 | =item EV_EMBED_ENABLE |
|
|
2433 | |
|
|
2434 | If undefined or defined to be C<1>, then embed watchers are supported. If |
|
|
2435 | defined to be C<0>, then they are not. |
|
|
2436 | |
|
|
2437 | =item EV_STAT_ENABLE |
|
|
2438 | |
|
|
2439 | If undefined or defined to be C<1>, then stat watchers are supported. If |
|
|
2440 | defined to be C<0>, then they are not. |
|
|
2441 | |
|
|
2442 | =item EV_FORK_ENABLE |
|
|
2443 | |
|
|
2444 | If undefined or defined to be C<1>, then fork watchers are supported. If |
|
|
2445 | defined to be C<0>, then they are not. |
|
|
2446 | |
|
|
2447 | =item EV_MINIMAL |
|
|
2448 | |
|
|
2449 | If you need to shave off some kilobytes of code at the expense of some |
|
|
2450 | speed, define this symbol to C<1>. Currently only used for gcc to override |
|
|
2451 | some inlining decisions, saves roughly 30% codesize of amd64. |
|
|
2452 | |
|
|
2453 | =item EV_PID_HASHSIZE |
|
|
2454 | |
|
|
2455 | C<ev_child> watchers use a small hash table to distribute workload by |
|
|
2456 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
|
|
2457 | than enough. If you need to manage thousands of children you might want to |
|
|
2458 | increase this value (I<must> be a power of two). |
|
|
2459 | |
|
|
2460 | =item EV_INOTIFY_HASHSIZE |
|
|
2461 | |
|
|
2462 | C<ev_staz> watchers use a small hash table to distribute workload by |
|
|
2463 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
|
|
2464 | usually more than enough. If you need to manage thousands of C<ev_stat> |
|
|
2465 | watchers you might want to increase this value (I<must> be a power of |
|
|
2466 | two). |
1638 | |
2467 | |
1639 | =item EV_COMMON |
2468 | =item EV_COMMON |
1640 | |
2469 | |
1641 | By default, all watchers have a C<void *data> member. By redefining |
2470 | By default, all watchers have a C<void *data> member. By redefining |
1642 | this macro to a something else you can include more and other types of |
2471 | this macro to a something else you can include more and other types of |
… | |
… | |
1647 | |
2476 | |
1648 | #define EV_COMMON \ |
2477 | #define EV_COMMON \ |
1649 | SV *self; /* contains this struct */ \ |
2478 | SV *self; /* contains this struct */ \ |
1650 | SV *cb_sv, *fh /* note no trailing ";" */ |
2479 | SV *cb_sv, *fh /* note no trailing ";" */ |
1651 | |
2480 | |
1652 | =item EV_CB_DECLARE(type) |
2481 | =item EV_CB_DECLARE (type) |
1653 | |
2482 | |
1654 | =item EV_CB_INVOKE(watcher,revents) |
2483 | =item EV_CB_INVOKE (watcher, revents) |
1655 | |
2484 | |
1656 | =item ev_set_cb(ev,cb) |
2485 | =item ev_set_cb (ev, cb) |
1657 | |
2486 | |
1658 | Can be used to change the callback member declaration in each watcher, |
2487 | Can be used to change the callback member declaration in each watcher, |
1659 | and the way callbacks are invoked and set. Must expand to a struct member |
2488 | and the way callbacks are invoked and set. Must expand to a struct member |
1660 | definition and a statement, respectively. See the F<ev.v> header file for |
2489 | definition and a statement, respectively. See the F<ev.h> header file for |
1661 | their default definitions. One possible use for overriding these is to |
2490 | their default definitions. One possible use for overriding these is to |
1662 | avoid the ev_loop pointer as first argument in all cases, or to use method |
2491 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
1663 | calls instead of plain function calls in C++. |
2492 | method calls instead of plain function calls in C++. |
|
|
2493 | |
|
|
2494 | =head2 EXPORTED API SYMBOLS |
|
|
2495 | |
|
|
2496 | If you need to re-export the API (e.g. via a dll) and you need a list of |
|
|
2497 | exported symbols, you can use the provided F<Symbol.*> files which list |
|
|
2498 | all public symbols, one per line: |
|
|
2499 | |
|
|
2500 | Symbols.ev for libev proper |
|
|
2501 | Symbols.event for the libevent emulation |
|
|
2502 | |
|
|
2503 | This can also be used to rename all public symbols to avoid clashes with |
|
|
2504 | multiple versions of libev linked together (which is obviously bad in |
|
|
2505 | itself, but sometimes it is inconvinient to avoid this). |
|
|
2506 | |
|
|
2507 | A sed command like this will create wrapper C<#define>'s that you need to |
|
|
2508 | include before including F<ev.h>: |
|
|
2509 | |
|
|
2510 | <Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h |
|
|
2511 | |
|
|
2512 | This would create a file F<wrap.h> which essentially looks like this: |
|
|
2513 | |
|
|
2514 | #define ev_backend myprefix_ev_backend |
|
|
2515 | #define ev_check_start myprefix_ev_check_start |
|
|
2516 | #define ev_check_stop myprefix_ev_check_stop |
|
|
2517 | ... |
1664 | |
2518 | |
1665 | =head2 EXAMPLES |
2519 | =head2 EXAMPLES |
1666 | |
2520 | |
1667 | For a real-world example of a program the includes libev |
2521 | For a real-world example of a program the includes libev |
1668 | verbatim, you can have a look at the EV perl module |
2522 | verbatim, you can have a look at the EV perl module |
… | |
… | |
1671 | interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file |
2525 | interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file |
1672 | will be compiled. It is pretty complex because it provides its own header |
2526 | will be compiled. It is pretty complex because it provides its own header |
1673 | file. |
2527 | file. |
1674 | |
2528 | |
1675 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
2529 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
1676 | that everybody includes and which overrides some autoconf choices: |
2530 | that everybody includes and which overrides some configure choices: |
1677 | |
2531 | |
|
|
2532 | #define EV_MINIMAL 1 |
1678 | #define EV_USE_POLL 0 |
2533 | #define EV_USE_POLL 0 |
1679 | #define EV_MULTIPLICITY 0 |
2534 | #define EV_MULTIPLICITY 0 |
1680 | #define EV_PERIODICS 0 |
2535 | #define EV_PERIODIC_ENABLE 0 |
|
|
2536 | #define EV_STAT_ENABLE 0 |
|
|
2537 | #define EV_FORK_ENABLE 0 |
1681 | #define EV_CONFIG_H <config.h> |
2538 | #define EV_CONFIG_H <config.h> |
|
|
2539 | #define EV_MINPRI 0 |
|
|
2540 | #define EV_MAXPRI 0 |
1682 | |
2541 | |
1683 | #include "ev++.h" |
2542 | #include "ev++.h" |
1684 | |
2543 | |
1685 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
2544 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
1686 | |
2545 | |
1687 | #include "ev_cpp.h" |
2546 | #include "ev_cpp.h" |
1688 | #include "ev.c" |
2547 | #include "ev.c" |
1689 | |
2548 | |
|
|
2549 | |
|
|
2550 | =head1 COMPLEXITIES |
|
|
2551 | |
|
|
2552 | In this section the complexities of (many of) the algorithms used inside |
|
|
2553 | libev will be explained. For complexity discussions about backends see the |
|
|
2554 | documentation for C<ev_default_init>. |
|
|
2555 | |
|
|
2556 | All of the following are about amortised time: If an array needs to be |
|
|
2557 | extended, libev needs to realloc and move the whole array, but this |
|
|
2558 | happens asymptotically never with higher number of elements, so O(1) might |
|
|
2559 | mean it might do a lengthy realloc operation in rare cases, but on average |
|
|
2560 | it is much faster and asymptotically approaches constant time. |
|
|
2561 | |
|
|
2562 | =over 4 |
|
|
2563 | |
|
|
2564 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
|
|
2565 | |
|
|
2566 | This means that, when you have a watcher that triggers in one hour and |
|
|
2567 | there are 100 watchers that would trigger before that then inserting will |
|
|
2568 | have to skip those 100 watchers. |
|
|
2569 | |
|
|
2570 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
|
|
2571 | |
|
|
2572 | That means that for changing a timer costs less than removing/adding them |
|
|
2573 | as only the relative motion in the event queue has to be paid for. |
|
|
2574 | |
|
|
2575 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
|
|
2576 | |
|
|
2577 | These just add the watcher into an array or at the head of a list. |
|
|
2578 | =item Stopping check/prepare/idle watchers: O(1) |
|
|
2579 | |
|
|
2580 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
|
|
2581 | |
|
|
2582 | These watchers are stored in lists then need to be walked to find the |
|
|
2583 | correct watcher to remove. The lists are usually short (you don't usually |
|
|
2584 | have many watchers waiting for the same fd or signal). |
|
|
2585 | |
|
|
2586 | =item Finding the next timer per loop iteration: O(1) |
|
|
2587 | |
|
|
2588 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
|
|
2589 | |
|
|
2590 | A change means an I/O watcher gets started or stopped, which requires |
|
|
2591 | libev to recalculate its status (and possibly tell the kernel). |
|
|
2592 | |
|
|
2593 | =item Activating one watcher: O(1) |
|
|
2594 | |
|
|
2595 | =item Priority handling: O(number_of_priorities) |
|
|
2596 | |
|
|
2597 | Priorities are implemented by allocating some space for each |
|
|
2598 | priority. When doing priority-based operations, libev usually has to |
|
|
2599 | linearly search all the priorities. |
|
|
2600 | |
|
|
2601 | =back |
|
|
2602 | |
|
|
2603 | |
1690 | =head1 AUTHOR |
2604 | =head1 AUTHOR |
1691 | |
2605 | |
1692 | Marc Lehmann <libev@schmorp.de>. |
2606 | Marc Lehmann <libev@schmorp.de>. |
1693 | |
2607 | |