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2 | |
2 | |
3 | libev - a high performance full-featured event loop written in C |
3 | libev - a high performance full-featured event loop written in C |
4 | |
4 | |
5 | =head1 SYNOPSIS |
5 | =head1 SYNOPSIS |
6 | |
6 | |
7 | #include <ev.h> |
7 | #include <ev.h> |
8 | |
8 | |
9 | =head2 EXAMPLE PROGRAM |
9 | =head2 EXAMPLE PROGRAM |
10 | |
10 | |
11 | // a single header file is required |
11 | // a single header file is required |
12 | #include <ev.h> |
12 | #include <ev.h> |
13 | |
13 | |
14 | // every watcher type has its own typedef'd struct |
14 | // every watcher type has its own typedef'd struct |
15 | // with the name ev_<type> |
15 | // with the name ev_<type> |
16 | ev_io stdin_watcher; |
16 | ev_io stdin_watcher; |
17 | ev_timer timeout_watcher; |
17 | ev_timer timeout_watcher; |
18 | |
18 | |
19 | // all watcher callbacks have a similar signature |
19 | // all watcher callbacks have a similar signature |
20 | // this callback is called when data is readable on stdin |
20 | // this callback is called when data is readable on stdin |
21 | static void |
21 | static void |
22 | stdin_cb (EV_P_ struct ev_io *w, int revents) |
22 | stdin_cb (EV_P_ struct ev_io *w, int revents) |
23 | { |
23 | { |
24 | puts ("stdin ready"); |
24 | puts ("stdin ready"); |
25 | // for one-shot events, one must manually stop the watcher |
25 | // for one-shot events, one must manually stop the watcher |
26 | // with its corresponding stop function. |
26 | // with its corresponding stop function. |
27 | ev_io_stop (EV_A_ w); |
27 | ev_io_stop (EV_A_ w); |
28 | |
28 | |
29 | // this causes all nested ev_loop's to stop iterating |
29 | // this causes all nested ev_loop's to stop iterating |
30 | ev_unloop (EV_A_ EVUNLOOP_ALL); |
30 | ev_unloop (EV_A_ EVUNLOOP_ALL); |
31 | } |
31 | } |
32 | |
32 | |
33 | // another callback, this time for a time-out |
33 | // another callback, this time for a time-out |
34 | static void |
34 | static void |
35 | timeout_cb (EV_P_ struct ev_timer *w, int revents) |
35 | timeout_cb (EV_P_ struct ev_timer *w, int revents) |
36 | { |
36 | { |
37 | puts ("timeout"); |
37 | puts ("timeout"); |
38 | // this causes the innermost ev_loop to stop iterating |
38 | // this causes the innermost ev_loop to stop iterating |
39 | ev_unloop (EV_A_ EVUNLOOP_ONE); |
39 | ev_unloop (EV_A_ EVUNLOOP_ONE); |
40 | } |
40 | } |
41 | |
41 | |
42 | int |
42 | int |
43 | main (void) |
43 | main (void) |
44 | { |
44 | { |
45 | // use the default event loop unless you have special needs |
45 | // use the default event loop unless you have special needs |
46 | struct ev_loop *loop = ev_default_loop (0); |
46 | struct ev_loop *loop = ev_default_loop (0); |
47 | |
47 | |
48 | // initialise an io watcher, then start it |
48 | // initialise an io watcher, then start it |
49 | // this one will watch for stdin to become readable |
49 | // this one will watch for stdin to become readable |
50 | ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
50 | ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
51 | ev_io_start (loop, &stdin_watcher); |
51 | ev_io_start (loop, &stdin_watcher); |
52 | |
52 | |
53 | // initialise a timer watcher, then start it |
53 | // initialise a timer watcher, then start it |
54 | // simple non-repeating 5.5 second timeout |
54 | // simple non-repeating 5.5 second timeout |
55 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
55 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
56 | ev_timer_start (loop, &timeout_watcher); |
56 | ev_timer_start (loop, &timeout_watcher); |
57 | |
57 | |
58 | // now wait for events to arrive |
58 | // now wait for events to arrive |
59 | ev_loop (loop, 0); |
59 | ev_loop (loop, 0); |
60 | |
60 | |
61 | // unloop was called, so exit |
61 | // unloop was called, so exit |
62 | return 0; |
62 | return 0; |
63 | } |
63 | } |
64 | |
64 | |
65 | =head1 DESCRIPTION |
65 | =head1 DESCRIPTION |
66 | |
66 | |
67 | The newest version of this document is also available as an html-formatted |
67 | The newest version of this document is also available as an html-formatted |
68 | web page you might find easier to navigate when reading it for the first |
68 | web page you might find easier to navigate when reading it for the first |
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113 | Libev represents time as a single floating point number, representing the |
113 | Libev represents time as a single floating point number, representing the |
114 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
114 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
115 | the beginning of 1970, details are complicated, don't ask). This type is |
115 | the beginning of 1970, details are complicated, don't ask). This type is |
116 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
116 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
117 | to the C<double> type in C, and when you need to do any calculations on |
117 | to the C<double> type in C, and when you need to do any calculations on |
118 | it, you should treat it as some floatingpoint value. Unlike the name |
118 | it, you should treat it as some floating point value. Unlike the name |
119 | component C<stamp> might indicate, it is also used for time differences |
119 | component C<stamp> might indicate, it is also used for time differences |
120 | throughout libev. |
120 | throughout libev. |
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121 | |
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122 | =head1 ERROR HANDLING |
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123 | |
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124 | Libev knows three classes of errors: operating system errors, usage errors |
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125 | and internal errors (bugs). |
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126 | |
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127 | When libev catches an operating system error it cannot handle (for example |
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128 | a system call indicating a condition libev cannot fix), it calls the callback |
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129 | set via C<ev_set_syserr_cb>, which is supposed to fix the problem or |
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130 | abort. The default is to print a diagnostic message and to call C<abort |
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131 | ()>. |
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132 | |
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133 | When libev detects a usage error such as a negative timer interval, then |
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134 | it will print a diagnostic message and abort (via the C<assert> mechanism, |
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135 | so C<NDEBUG> will disable this checking): these are programming errors in |
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136 | the libev caller and need to be fixed there. |
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137 | |
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138 | Libev also has a few internal error-checking C<assert>ions, and also has |
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139 | extensive consistency checking code. These do not trigger under normal |
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140 | circumstances, as they indicate either a bug in libev or worse. |
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141 | |
121 | |
142 | |
122 | =head1 GLOBAL FUNCTIONS |
143 | =head1 GLOBAL FUNCTIONS |
123 | |
144 | |
124 | These functions can be called anytime, even before initialising the |
145 | These functions can be called anytime, even before initialising the |
125 | library in any way. |
146 | library in any way. |
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134 | |
155 | |
135 | =item ev_sleep (ev_tstamp interval) |
156 | =item ev_sleep (ev_tstamp interval) |
136 | |
157 | |
137 | Sleep for the given interval: The current thread will be blocked until |
158 | Sleep for the given interval: The current thread will be blocked until |
138 | either it is interrupted or the given time interval has passed. Basically |
159 | either it is interrupted or the given time interval has passed. Basically |
139 | this is a subsecond-resolution C<sleep ()>. |
160 | this is a sub-second-resolution C<sleep ()>. |
140 | |
161 | |
141 | =item int ev_version_major () |
162 | =item int ev_version_major () |
142 | |
163 | |
143 | =item int ev_version_minor () |
164 | =item int ev_version_minor () |
144 | |
165 | |
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157 | not a problem. |
178 | not a problem. |
158 | |
179 | |
159 | Example: Make sure we haven't accidentally been linked against the wrong |
180 | Example: Make sure we haven't accidentally been linked against the wrong |
160 | version. |
181 | version. |
161 | |
182 | |
162 | assert (("libev version mismatch", |
183 | assert (("libev version mismatch", |
163 | ev_version_major () == EV_VERSION_MAJOR |
184 | ev_version_major () == EV_VERSION_MAJOR |
164 | && ev_version_minor () >= EV_VERSION_MINOR)); |
185 | && ev_version_minor () >= EV_VERSION_MINOR)); |
165 | |
186 | |
166 | =item unsigned int ev_supported_backends () |
187 | =item unsigned int ev_supported_backends () |
167 | |
188 | |
168 | Return the set of all backends (i.e. their corresponding C<EV_BACKEND_*> |
189 | Return the set of all backends (i.e. their corresponding C<EV_BACKEND_*> |
169 | value) compiled into this binary of libev (independent of their |
190 | value) compiled into this binary of libev (independent of their |
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171 | a description of the set values. |
192 | a description of the set values. |
172 | |
193 | |
173 | Example: make sure we have the epoll method, because yeah this is cool and |
194 | Example: make sure we have the epoll method, because yeah this is cool and |
174 | a must have and can we have a torrent of it please!!!11 |
195 | a must have and can we have a torrent of it please!!!11 |
175 | |
196 | |
176 | assert (("sorry, no epoll, no sex", |
197 | assert (("sorry, no epoll, no sex", |
177 | ev_supported_backends () & EVBACKEND_EPOLL)); |
198 | ev_supported_backends () & EVBACKEND_EPOLL)); |
178 | |
199 | |
179 | =item unsigned int ev_recommended_backends () |
200 | =item unsigned int ev_recommended_backends () |
180 | |
201 | |
181 | Return the set of all backends compiled into this binary of libev and also |
202 | Return the set of all backends compiled into this binary of libev and also |
182 | recommended for this platform. This set is often smaller than the one |
203 | recommended for this platform. This set is often smaller than the one |
183 | returned by C<ev_supported_backends>, as for example kqueue is broken on |
204 | returned by C<ev_supported_backends>, as for example kqueue is broken on |
184 | most BSDs and will not be autodetected unless you explicitly request it |
205 | most BSDs and will not be auto-detected unless you explicitly request it |
185 | (assuming you know what you are doing). This is the set of backends that |
206 | (assuming you know what you are doing). This is the set of backends that |
186 | libev will probe for if you specify no backends explicitly. |
207 | libev will probe for if you specify no backends explicitly. |
187 | |
208 | |
188 | =item unsigned int ev_embeddable_backends () |
209 | =item unsigned int ev_embeddable_backends () |
189 | |
210 | |
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193 | C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for |
214 | C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for |
194 | recommended ones. |
215 | recommended ones. |
195 | |
216 | |
196 | See the description of C<ev_embed> watchers for more info. |
217 | See the description of C<ev_embed> watchers for more info. |
197 | |
218 | |
198 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
219 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT] |
199 | |
220 | |
200 | Sets the allocation function to use (the prototype is similar - the |
221 | Sets the allocation function to use (the prototype is similar - the |
201 | semantics are identical to the C<realloc> C89/SuS/POSIX function). It is |
222 | semantics are identical to the C<realloc> C89/SuS/POSIX function). It is |
202 | used to allocate and free memory (no surprises here). If it returns zero |
223 | used to allocate and free memory (no surprises here). If it returns zero |
203 | when memory needs to be allocated (C<size != 0>), the library might abort |
224 | when memory needs to be allocated (C<size != 0>), the library might abort |
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229 | } |
250 | } |
230 | |
251 | |
231 | ... |
252 | ... |
232 | ev_set_allocator (persistent_realloc); |
253 | ev_set_allocator (persistent_realloc); |
233 | |
254 | |
234 | =item ev_set_syserr_cb (void (*cb)(const char *msg)); |
255 | =item ev_set_syserr_cb (void (*cb)(const char *msg)); [NOT REENTRANT] |
235 | |
256 | |
236 | Set the callback function to call on a retryable syscall error (such |
257 | Set the callback function to call on a retryable system call error (such |
237 | as failed select, poll, epoll_wait). The message is a printable string |
258 | as failed select, poll, epoll_wait). The message is a printable string |
238 | indicating the system call or subsystem causing the problem. If this |
259 | indicating the system call or subsystem causing the problem. If this |
239 | callback is set, then libev will expect it to remedy the sitution, no |
260 | callback is set, then libev will expect it to remedy the situation, no |
240 | matter what, when it returns. That is, libev will generally retry the |
261 | matter what, when it returns. That is, libev will generally retry the |
241 | requested operation, or, if the condition doesn't go away, do bad stuff |
262 | requested operation, or, if the condition doesn't go away, do bad stuff |
242 | (such as abort). |
263 | (such as abort). |
243 | |
264 | |
244 | Example: This is basically the same thing that libev does internally, too. |
265 | Example: This is basically the same thing that libev does internally, too. |
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277 | from multiple threads, you have to lock (note also that this is unlikely, |
298 | from multiple threads, you have to lock (note also that this is unlikely, |
278 | as loops cannot bes hared easily between threads anyway). |
299 | as loops cannot bes hared easily between threads anyway). |
279 | |
300 | |
280 | The default loop is the only loop that can handle C<ev_signal> and |
301 | The default loop is the only loop that can handle C<ev_signal> and |
281 | C<ev_child> watchers, and to do this, it always registers a handler |
302 | C<ev_child> watchers, and to do this, it always registers a handler |
282 | for C<SIGCHLD>. If this is a problem for your app you can either |
303 | for C<SIGCHLD>. If this is a problem for your application you can either |
283 | create a dynamic loop with C<ev_loop_new> that doesn't do that, or you |
304 | create a dynamic loop with C<ev_loop_new> that doesn't do that, or you |
284 | can simply overwrite the C<SIGCHLD> signal handler I<after> calling |
305 | can simply overwrite the C<SIGCHLD> signal handler I<after> calling |
285 | C<ev_default_init>. |
306 | C<ev_default_init>. |
286 | |
307 | |
287 | The flags argument can be used to specify special behaviour or specific |
308 | The flags argument can be used to specify special behaviour or specific |
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296 | The default flags value. Use this if you have no clue (it's the right |
317 | The default flags value. Use this if you have no clue (it's the right |
297 | thing, believe me). |
318 | thing, believe me). |
298 | |
319 | |
299 | =item C<EVFLAG_NOENV> |
320 | =item C<EVFLAG_NOENV> |
300 | |
321 | |
301 | If this flag bit is ored into the flag value (or the program runs setuid |
322 | If this flag bit is or'ed into the flag value (or the program runs setuid |
302 | or setgid) then libev will I<not> look at the environment variable |
323 | or setgid) then libev will I<not> look at the environment variable |
303 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
324 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
304 | override the flags completely if it is found in the environment. This is |
325 | override the flags completely if it is found in the environment. This is |
305 | useful to try out specific backends to test their performance, or to work |
326 | useful to try out specific backends to test their performance, or to work |
306 | around bugs. |
327 | around bugs. |
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313 | |
334 | |
314 | This works by calling C<getpid ()> on every iteration of the loop, |
335 | This works by calling C<getpid ()> on every iteration of the loop, |
315 | and thus this might slow down your event loop if you do a lot of loop |
336 | and thus this might slow down your event loop if you do a lot of loop |
316 | iterations and little real work, but is usually not noticeable (on my |
337 | iterations and little real work, but is usually not noticeable (on my |
317 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence |
338 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence |
318 | without a syscall and thus I<very> fast, but my GNU/Linux system also has |
339 | without a system call and thus I<very> fast, but my GNU/Linux system also has |
319 | C<pthread_atfork> which is even faster). |
340 | C<pthread_atfork> which is even faster). |
320 | |
341 | |
321 | The big advantage of this flag is that you can forget about fork (and |
342 | The big advantage of this flag is that you can forget about fork (and |
322 | forget about forgetting to tell libev about forking) when you use this |
343 | forget about forgetting to tell libev about forking) when you use this |
323 | flag. |
344 | flag. |
324 | |
345 | |
325 | This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS> |
346 | This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS> |
326 | environment variable. |
347 | environment variable. |
327 | |
348 | |
328 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
349 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
329 | |
350 | |
330 | This is your standard select(2) backend. Not I<completely> standard, as |
351 | This is your standard select(2) backend. Not I<completely> standard, as |
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332 | but if that fails, expect a fairly low limit on the number of fds when |
353 | but if that fails, expect a fairly low limit on the number of fds when |
333 | using this backend. It doesn't scale too well (O(highest_fd)), but its |
354 | using this backend. It doesn't scale too well (O(highest_fd)), but its |
334 | usually the fastest backend for a low number of (low-numbered :) fds. |
355 | usually the fastest backend for a low number of (low-numbered :) fds. |
335 | |
356 | |
336 | To get good performance out of this backend you need a high amount of |
357 | To get good performance out of this backend you need a high amount of |
337 | parallelity (most of the file descriptors should be busy). If you are |
358 | parallelism (most of the file descriptors should be busy). If you are |
338 | writing a server, you should C<accept ()> in a loop to accept as many |
359 | writing a server, you should C<accept ()> in a loop to accept as many |
339 | connections as possible during one iteration. You might also want to have |
360 | connections as possible during one iteration. You might also want to have |
340 | a look at C<ev_set_io_collect_interval ()> to increase the amount of |
361 | a look at C<ev_set_io_collect_interval ()> to increase the amount of |
341 | readyness notifications you get per iteration. |
362 | readiness notifications you get per iteration. |
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363 | |
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364 | This backend maps C<EV_READ> to the C<readfds> set and C<EV_WRITE> to the |
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365 | C<writefds> set (and to work around Microsoft Windows bugs, also onto the |
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366 | C<exceptfds> set on that platform). |
342 | |
367 | |
343 | =item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows) |
368 | =item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows) |
344 | |
369 | |
345 | And this is your standard poll(2) backend. It's more complicated |
370 | And this is your standard poll(2) backend. It's more complicated |
346 | than select, but handles sparse fds better and has no artificial |
371 | than select, but handles sparse fds better and has no artificial |
347 | limit on the number of fds you can use (except it will slow down |
372 | limit on the number of fds you can use (except it will slow down |
348 | considerably with a lot of inactive fds). It scales similarly to select, |
373 | considerably with a lot of inactive fds). It scales similarly to select, |
349 | i.e. O(total_fds). See the entry for C<EVBACKEND_SELECT>, above, for |
374 | i.e. O(total_fds). See the entry for C<EVBACKEND_SELECT>, above, for |
350 | performance tips. |
375 | performance tips. |
351 | |
376 | |
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377 | This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and |
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378 | C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>. |
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379 | |
352 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
380 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
353 | |
381 | |
354 | For few fds, this backend is a bit little slower than poll and select, |
382 | For few fds, this backend is a bit little slower than poll and select, |
355 | but it scales phenomenally better. While poll and select usually scale |
383 | but it scales phenomenally better. While poll and select usually scale |
356 | like O(total_fds) where n is the total number of fds (or the highest fd), |
384 | like O(total_fds) where n is the total number of fds (or the highest fd), |
357 | epoll scales either O(1) or O(active_fds). The epoll design has a number |
385 | epoll scales either O(1) or O(active_fds). The epoll design has a number |
358 | of shortcomings, such as silently dropping events in some hard-to-detect |
386 | of shortcomings, such as silently dropping events in some hard-to-detect |
359 | cases and requiring a syscall per fd change, no fork support and bad |
387 | cases and requiring a system call per fd change, no fork support and bad |
360 | support for dup. |
388 | support for dup. |
361 | |
389 | |
362 | While stopping, setting and starting an I/O watcher in the same iteration |
390 | While stopping, setting and starting an I/O watcher in the same iteration |
363 | will result in some caching, there is still a syscall per such incident |
391 | will result in some caching, there is still a system call per such incident |
364 | (because the fd could point to a different file description now), so its |
392 | (because the fd could point to a different file description now), so its |
365 | best to avoid that. Also, C<dup ()>'ed file descriptors might not work |
393 | best to avoid that. Also, C<dup ()>'ed file descriptors might not work |
366 | very well if you register events for both fds. |
394 | very well if you register events for both fds. |
367 | |
395 | |
368 | Please note that epoll sometimes generates spurious notifications, so you |
396 | Please note that epoll sometimes generates spurious notifications, so you |
369 | need to use non-blocking I/O or other means to avoid blocking when no data |
397 | need to use non-blocking I/O or other means to avoid blocking when no data |
370 | (or space) is available. |
398 | (or space) is available. |
371 | |
399 | |
372 | Best performance from this backend is achieved by not unregistering all |
400 | Best performance from this backend is achieved by not unregistering all |
373 | watchers for a file descriptor until it has been closed, if possible, i.e. |
401 | watchers for a file descriptor until it has been closed, if possible, |
374 | keep at least one watcher active per fd at all times. |
402 | i.e. keep at least one watcher active per fd at all times. Stopping and |
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403 | starting a watcher (without re-setting it) also usually doesn't cause |
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404 | extra overhead. |
375 | |
405 | |
376 | While nominally embeddeble in other event loops, this feature is broken in |
406 | While nominally embeddable in other event loops, this feature is broken in |
377 | all kernel versions tested so far. |
407 | all kernel versions tested so far. |
378 | |
408 | |
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409 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
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410 | C<EVBACKEND_POLL>. |
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411 | |
379 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
412 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
380 | |
413 | |
381 | Kqueue deserves special mention, as at the time of this writing, it |
414 | Kqueue deserves special mention, as at the time of this writing, it was |
382 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
415 | broken on all BSDs except NetBSD (usually it doesn't work reliably with |
383 | with anything but sockets and pipes, except on Darwin, where of course |
416 | anything but sockets and pipes, except on Darwin, where of course it's |
384 | it's completely useless). For this reason it's not being "autodetected" |
417 | completely useless). For this reason it's not being "auto-detected" unless |
385 | unless you explicitly specify it explicitly in the flags (i.e. using |
418 | you explicitly specify it in the flags (i.e. using C<EVBACKEND_KQUEUE>) or |
386 | C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough) |
419 | libev was compiled on a known-to-be-good (-enough) system like NetBSD. |
387 | system like NetBSD. |
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388 | |
420 | |
389 | You still can embed kqueue into a normal poll or select backend and use it |
421 | You still can embed kqueue into a normal poll or select backend and use it |
390 | only for sockets (after having made sure that sockets work with kqueue on |
422 | only for sockets (after having made sure that sockets work with kqueue on |
391 | the target platform). See C<ev_embed> watchers for more info. |
423 | the target platform). See C<ev_embed> watchers for more info. |
392 | |
424 | |
393 | It scales in the same way as the epoll backend, but the interface to the |
425 | It scales in the same way as the epoll backend, but the interface to the |
394 | kernel is more efficient (which says nothing about its actual speed, of |
426 | kernel is more efficient (which says nothing about its actual speed, of |
395 | course). While stopping, setting and starting an I/O watcher does never |
427 | course). While stopping, setting and starting an I/O watcher does never |
396 | cause an extra syscall as with C<EVBACKEND_EPOLL>, it still adds up to |
428 | cause an extra system call as with C<EVBACKEND_EPOLL>, it still adds up to |
397 | two event changes per incident, support for C<fork ()> is very bad and it |
429 | two event changes per incident. Support for C<fork ()> is very bad and it |
398 | drops fds silently in similarly hard-to-detect cases. |
430 | drops fds silently in similarly hard-to-detect cases. |
399 | |
431 | |
400 | This backend usually performs well under most conditions. |
432 | This backend usually performs well under most conditions. |
401 | |
433 | |
402 | While nominally embeddable in other event loops, this doesn't work |
434 | While nominally embeddable in other event loops, this doesn't work |
403 | everywhere, so you might need to test for this. And since it is broken |
435 | everywhere, so you might need to test for this. And since it is broken |
404 | almost everywhere, you should only use it when you have a lot of sockets |
436 | almost everywhere, you should only use it when you have a lot of sockets |
405 | (for which it usually works), by embedding it into another event loop |
437 | (for which it usually works), by embedding it into another event loop |
406 | (e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>) and using it only for |
438 | (e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>) and, did I mention it, |
407 | sockets. |
439 | using it only for sockets. |
|
|
440 | |
|
|
441 | This backend maps C<EV_READ> into an C<EVFILT_READ> kevent with |
|
|
442 | C<NOTE_EOF>, and C<EV_WRITE> into an C<EVFILT_WRITE> kevent with |
|
|
443 | C<NOTE_EOF>. |
408 | |
444 | |
409 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
445 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
410 | |
446 | |
411 | This is not implemented yet (and might never be, unless you send me an |
447 | This is not implemented yet (and might never be, unless you send me an |
412 | implementation). According to reports, C</dev/poll> only supports sockets |
448 | implementation). According to reports, C</dev/poll> only supports sockets |
… | |
… | |
416 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
452 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
417 | |
453 | |
418 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
454 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
419 | it's really slow, but it still scales very well (O(active_fds)). |
455 | it's really slow, but it still scales very well (O(active_fds)). |
420 | |
456 | |
421 | Please note that solaris event ports can deliver a lot of spurious |
457 | Please note that Solaris event ports can deliver a lot of spurious |
422 | notifications, so you need to use non-blocking I/O or other means to avoid |
458 | notifications, so you need to use non-blocking I/O or other means to avoid |
423 | blocking when no data (or space) is available. |
459 | blocking when no data (or space) is available. |
424 | |
460 | |
425 | While this backend scales well, it requires one system call per active |
461 | While this backend scales well, it requires one system call per active |
426 | file descriptor per loop iteration. For small and medium numbers of file |
462 | file descriptor per loop iteration. For small and medium numbers of file |
427 | descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend |
463 | descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend |
428 | might perform better. |
464 | might perform better. |
429 | |
465 | |
430 | On the positive side, ignoring the spurious readyness notifications, this |
466 | On the positive side, with the exception of the spurious readiness |
431 | backend actually performed to specification in all tests and is fully |
467 | notifications, this backend actually performed fully to specification |
432 | embeddable, which is a rare feat among the OS-specific backends. |
468 | in all tests and is fully embeddable, which is a rare feat among the |
|
|
469 | OS-specific backends. |
|
|
470 | |
|
|
471 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
|
|
472 | C<EVBACKEND_POLL>. |
433 | |
473 | |
434 | =item C<EVBACKEND_ALL> |
474 | =item C<EVBACKEND_ALL> |
435 | |
475 | |
436 | Try all backends (even potentially broken ones that wouldn't be tried |
476 | Try all backends (even potentially broken ones that wouldn't be tried |
437 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
477 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
… | |
… | |
439 | |
479 | |
440 | It is definitely not recommended to use this flag. |
480 | It is definitely not recommended to use this flag. |
441 | |
481 | |
442 | =back |
482 | =back |
443 | |
483 | |
444 | If one or more of these are ored into the flags value, then only these |
484 | If one or more of these are or'ed into the flags value, then only these |
445 | backends will be tried (in the reverse order as listed here). If none are |
485 | backends will be tried (in the reverse order as listed here). If none are |
446 | specified, all backends in C<ev_recommended_backends ()> will be tried. |
486 | specified, all backends in C<ev_recommended_backends ()> will be tried. |
447 | |
487 | |
448 | The most typical usage is like this: |
488 | Example: This is the most typical usage. |
449 | |
489 | |
450 | if (!ev_default_loop (0)) |
490 | if (!ev_default_loop (0)) |
451 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
491 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
452 | |
492 | |
453 | Restrict libev to the select and poll backends, and do not allow |
493 | Example: Restrict libev to the select and poll backends, and do not allow |
454 | environment settings to be taken into account: |
494 | environment settings to be taken into account: |
455 | |
495 | |
456 | ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
496 | ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
457 | |
497 | |
458 | Use whatever libev has to offer, but make sure that kqueue is used if |
498 | Example: Use whatever libev has to offer, but make sure that kqueue is |
459 | available (warning, breaks stuff, best use only with your own private |
499 | used if available (warning, breaks stuff, best use only with your own |
460 | event loop and only if you know the OS supports your types of fds): |
500 | private event loop and only if you know the OS supports your types of |
|
|
501 | fds): |
461 | |
502 | |
462 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
503 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
463 | |
504 | |
464 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
505 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
465 | |
506 | |
466 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
507 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
467 | always distinct from the default loop. Unlike the default loop, it cannot |
508 | always distinct from the default loop. Unlike the default loop, it cannot |
… | |
… | |
472 | libev with threads is indeed to create one loop per thread, and using the |
513 | libev with threads is indeed to create one loop per thread, and using the |
473 | default loop in the "main" or "initial" thread. |
514 | default loop in the "main" or "initial" thread. |
474 | |
515 | |
475 | Example: Try to create a event loop that uses epoll and nothing else. |
516 | Example: Try to create a event loop that uses epoll and nothing else. |
476 | |
517 | |
477 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
518 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
478 | if (!epoller) |
519 | if (!epoller) |
479 | fatal ("no epoll found here, maybe it hides under your chair"); |
520 | fatal ("no epoll found here, maybe it hides under your chair"); |
480 | |
521 | |
481 | =item ev_default_destroy () |
522 | =item ev_default_destroy () |
482 | |
523 | |
483 | Destroys the default loop again (frees all memory and kernel state |
524 | Destroys the default loop again (frees all memory and kernel state |
484 | etc.). None of the active event watchers will be stopped in the normal |
525 | etc.). None of the active event watchers will be stopped in the normal |
485 | sense, so e.g. C<ev_is_active> might still return true. It is your |
526 | sense, so e.g. C<ev_is_active> might still return true. It is your |
486 | responsibility to either stop all watchers cleanly yoursef I<before> |
527 | responsibility to either stop all watchers cleanly yourself I<before> |
487 | calling this function, or cope with the fact afterwards (which is usually |
528 | calling this function, or cope with the fact afterwards (which is usually |
488 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
529 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
489 | for example). |
530 | for example). |
490 | |
531 | |
491 | Note that certain global state, such as signal state, will not be freed by |
532 | Note that certain global state, such as signal state, will not be freed by |
… | |
… | |
523 | |
564 | |
524 | =item ev_loop_fork (loop) |
565 | =item ev_loop_fork (loop) |
525 | |
566 | |
526 | Like C<ev_default_fork>, but acts on an event loop created by |
567 | Like C<ev_default_fork>, but acts on an event loop created by |
527 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
568 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
528 | after fork, and how you do this is entirely your own problem. |
569 | after fork that you want to re-use in the child, and how you do this is |
|
|
570 | entirely your own problem. |
529 | |
571 | |
530 | =item int ev_is_default_loop (loop) |
572 | =item int ev_is_default_loop (loop) |
531 | |
573 | |
532 | Returns true when the given loop actually is the default loop, false otherwise. |
574 | Returns true when the given loop is, in fact, the default loop, and false |
|
|
575 | otherwise. |
533 | |
576 | |
534 | =item unsigned int ev_loop_count (loop) |
577 | =item unsigned int ev_loop_count (loop) |
535 | |
578 | |
536 | Returns the count of loop iterations for the loop, which is identical to |
579 | Returns the count of loop iterations for the loop, which is identical to |
537 | the number of times libev did poll for new events. It starts at C<0> and |
580 | the number of times libev did poll for new events. It starts at C<0> and |
… | |
… | |
552 | received events and started processing them. This timestamp does not |
595 | received events and started processing them. This timestamp does not |
553 | change as long as callbacks are being processed, and this is also the base |
596 | change as long as callbacks are being processed, and this is also the base |
554 | time used for relative timers. You can treat it as the timestamp of the |
597 | time used for relative timers. You can treat it as the timestamp of the |
555 | event occurring (or more correctly, libev finding out about it). |
598 | event occurring (or more correctly, libev finding out about it). |
556 | |
599 | |
|
|
600 | =item ev_now_update (loop) |
|
|
601 | |
|
|
602 | Establishes the current time by querying the kernel, updating the time |
|
|
603 | returned by C<ev_now ()> in the progress. This is a costly operation and |
|
|
604 | is usually done automatically within C<ev_loop ()>. |
|
|
605 | |
|
|
606 | This function is rarely useful, but when some event callback runs for a |
|
|
607 | very long time without entering the event loop, updating libev's idea of |
|
|
608 | the current time is a good idea. |
|
|
609 | |
|
|
610 | See also "The special problem of time updates" in the C<ev_timer> section. |
|
|
611 | |
557 | =item ev_loop (loop, int flags) |
612 | =item ev_loop (loop, int flags) |
558 | |
613 | |
559 | Finally, this is it, the event handler. This function usually is called |
614 | Finally, this is it, the event handler. This function usually is called |
560 | after you initialised all your watchers and you want to start handling |
615 | after you initialised all your watchers and you want to start handling |
561 | events. |
616 | events. |
… | |
… | |
563 | If the flags argument is specified as C<0>, it will not return until |
618 | If the flags argument is specified as C<0>, it will not return until |
564 | either no event watchers are active anymore or C<ev_unloop> was called. |
619 | either no event watchers are active anymore or C<ev_unloop> was called. |
565 | |
620 | |
566 | Please note that an explicit C<ev_unloop> is usually better than |
621 | Please note that an explicit C<ev_unloop> is usually better than |
567 | relying on all watchers to be stopped when deciding when a program has |
622 | relying on all watchers to be stopped when deciding when a program has |
568 | finished (especially in interactive programs), but having a program that |
623 | finished (especially in interactive programs), but having a program |
569 | automatically loops as long as it has to and no longer by virtue of |
624 | that automatically loops as long as it has to and no longer by virtue |
570 | relying on its watchers stopping correctly is a thing of beauty. |
625 | of relying on its watchers stopping correctly, that is truly a thing of |
|
|
626 | beauty. |
571 | |
627 | |
572 | A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle |
628 | A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle |
573 | those events and any outstanding ones, but will not block your process in |
629 | those events and any already outstanding ones, but will not block your |
574 | case there are no events and will return after one iteration of the loop. |
630 | process in case there are no events and will return after one iteration of |
|
|
631 | the loop. |
575 | |
632 | |
576 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
633 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
577 | neccessary) and will handle those and any outstanding ones. It will block |
634 | necessary) and will handle those and any already outstanding ones. It |
578 | your process until at least one new event arrives, and will return after |
635 | will block your process until at least one new event arrives (which could |
579 | one iteration of the loop. This is useful if you are waiting for some |
636 | be an event internal to libev itself, so there is no guarentee that a |
580 | external event in conjunction with something not expressible using other |
637 | user-registered callback will be called), and will return after one |
|
|
638 | iteration of the loop. |
|
|
639 | |
|
|
640 | This is useful if you are waiting for some external event in conjunction |
|
|
641 | with something not expressible using other libev watchers (i.e. "roll your |
581 | libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is |
642 | own C<ev_loop>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is |
582 | usually a better approach for this kind of thing. |
643 | usually a better approach for this kind of thing. |
583 | |
644 | |
584 | Here are the gory details of what C<ev_loop> does: |
645 | Here are the gory details of what C<ev_loop> does: |
585 | |
646 | |
586 | - Before the first iteration, call any pending watchers. |
647 | - Before the first iteration, call any pending watchers. |
587 | * If EVFLAG_FORKCHECK was used, check for a fork. |
648 | * If EVFLAG_FORKCHECK was used, check for a fork. |
588 | - If a fork was detected, queue and call all fork watchers. |
649 | - If a fork was detected (by any means), queue and call all fork watchers. |
589 | - Queue and call all prepare watchers. |
650 | - Queue and call all prepare watchers. |
590 | - If we have been forked, recreate the kernel state. |
651 | - If we have been forked, detach and recreate the kernel state |
|
|
652 | as to not disturb the other process. |
591 | - Update the kernel state with all outstanding changes. |
653 | - Update the kernel state with all outstanding changes. |
592 | - Update the "event loop time". |
654 | - Update the "event loop time" (ev_now ()). |
593 | - Calculate for how long to sleep or block, if at all |
655 | - Calculate for how long to sleep or block, if at all |
594 | (active idle watchers, EVLOOP_NONBLOCK or not having |
656 | (active idle watchers, EVLOOP_NONBLOCK or not having |
595 | any active watchers at all will result in not sleeping). |
657 | any active watchers at all will result in not sleeping). |
596 | - Sleep if the I/O and timer collect interval say so. |
658 | - Sleep if the I/O and timer collect interval say so. |
597 | - Block the process, waiting for any events. |
659 | - Block the process, waiting for any events. |
598 | - Queue all outstanding I/O (fd) events. |
660 | - Queue all outstanding I/O (fd) events. |
599 | - Update the "event loop time" and do time jump handling. |
661 | - Update the "event loop time" (ev_now ()), and do time jump adjustments. |
600 | - Queue all outstanding timers. |
662 | - Queue all expired timers. |
601 | - Queue all outstanding periodics. |
663 | - Queue all expired periodics. |
602 | - If no events are pending now, queue all idle watchers. |
664 | - Unless any events are pending now, queue all idle watchers. |
603 | - Queue all check watchers. |
665 | - Queue all check watchers. |
604 | - Call all queued watchers in reverse order (i.e. check watchers first). |
666 | - Call all queued watchers in reverse order (i.e. check watchers first). |
605 | Signals and child watchers are implemented as I/O watchers, and will |
667 | Signals and child watchers are implemented as I/O watchers, and will |
606 | be handled here by queueing them when their watcher gets executed. |
668 | be handled here by queueing them when their watcher gets executed. |
607 | - If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
669 | - If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
… | |
… | |
612 | anymore. |
674 | anymore. |
613 | |
675 | |
614 | ... queue jobs here, make sure they register event watchers as long |
676 | ... queue jobs here, make sure they register event watchers as long |
615 | ... as they still have work to do (even an idle watcher will do..) |
677 | ... as they still have work to do (even an idle watcher will do..) |
616 | ev_loop (my_loop, 0); |
678 | ev_loop (my_loop, 0); |
617 | ... jobs done. yeah! |
679 | ... jobs done or somebody called unloop. yeah! |
618 | |
680 | |
619 | =item ev_unloop (loop, how) |
681 | =item ev_unloop (loop, how) |
620 | |
682 | |
621 | Can be used to make a call to C<ev_loop> return early (but only after it |
683 | Can be used to make a call to C<ev_loop> return early (but only after it |
622 | has processed all outstanding events). The C<how> argument must be either |
684 | has processed all outstanding events). The C<how> argument must be either |
623 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
685 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
624 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
686 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
625 | |
687 | |
626 | This "unloop state" will be cleared when entering C<ev_loop> again. |
688 | This "unloop state" will be cleared when entering C<ev_loop> again. |
627 | |
689 | |
|
|
690 | It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls. |
|
|
691 | |
628 | =item ev_ref (loop) |
692 | =item ev_ref (loop) |
629 | |
693 | |
630 | =item ev_unref (loop) |
694 | =item ev_unref (loop) |
631 | |
695 | |
632 | Ref/unref can be used to add or remove a reference count on the event |
696 | Ref/unref can be used to add or remove a reference count on the event |
633 | loop: Every watcher keeps one reference, and as long as the reference |
697 | loop: Every watcher keeps one reference, and as long as the reference |
634 | count is nonzero, C<ev_loop> will not return on its own. If you have |
698 | count is nonzero, C<ev_loop> will not return on its own. |
|
|
699 | |
635 | a watcher you never unregister that should not keep C<ev_loop> from |
700 | If you have a watcher you never unregister that should not keep C<ev_loop> |
636 | returning, ev_unref() after starting, and ev_ref() before stopping it. For |
701 | from returning, call ev_unref() after starting, and ev_ref() before |
|
|
702 | stopping it. |
|
|
703 | |
637 | example, libev itself uses this for its internal signal pipe: It is not |
704 | As an example, libev itself uses this for its internal signal pipe: It is |
638 | visible to the libev user and should not keep C<ev_loop> from exiting if |
705 | not visible to the libev user and should not keep C<ev_loop> from exiting |
639 | no event watchers registered by it are active. It is also an excellent |
706 | if no event watchers registered by it are active. It is also an excellent |
640 | way to do this for generic recurring timers or from within third-party |
707 | way to do this for generic recurring timers or from within third-party |
641 | libraries. Just remember to I<unref after start> and I<ref before stop> |
708 | libraries. Just remember to I<unref after start> and I<ref before stop> |
642 | (but only if the watcher wasn't active before, or was active before, |
709 | (but only if the watcher wasn't active before, or was active before, |
643 | respectively). |
710 | respectively). |
644 | |
711 | |
645 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
712 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
646 | running when nothing else is active. |
713 | running when nothing else is active. |
647 | |
714 | |
648 | struct ev_signal exitsig; |
715 | struct ev_signal exitsig; |
649 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
716 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
650 | ev_signal_start (loop, &exitsig); |
717 | ev_signal_start (loop, &exitsig); |
651 | evf_unref (loop); |
718 | evf_unref (loop); |
652 | |
719 | |
653 | Example: For some weird reason, unregister the above signal handler again. |
720 | Example: For some weird reason, unregister the above signal handler again. |
654 | |
721 | |
655 | ev_ref (loop); |
722 | ev_ref (loop); |
656 | ev_signal_stop (loop, &exitsig); |
723 | ev_signal_stop (loop, &exitsig); |
657 | |
724 | |
658 | =item ev_set_io_collect_interval (loop, ev_tstamp interval) |
725 | =item ev_set_io_collect_interval (loop, ev_tstamp interval) |
659 | |
726 | |
660 | =item ev_set_timeout_collect_interval (loop, ev_tstamp interval) |
727 | =item ev_set_timeout_collect_interval (loop, ev_tstamp interval) |
661 | |
728 | |
662 | These advanced functions influence the time that libev will spend waiting |
729 | These advanced functions influence the time that libev will spend waiting |
663 | for events. Both are by default C<0>, meaning that libev will try to |
730 | for events. Both time intervals are by default C<0>, meaning that libev |
664 | invoke timer/periodic callbacks and I/O callbacks with minimum latency. |
731 | will try to invoke timer/periodic callbacks and I/O callbacks with minimum |
|
|
732 | latency. |
665 | |
733 | |
666 | Setting these to a higher value (the C<interval> I<must> be >= C<0>) |
734 | Setting these to a higher value (the C<interval> I<must> be >= C<0>) |
667 | allows libev to delay invocation of I/O and timer/periodic callbacks to |
735 | allows libev to delay invocation of I/O and timer/periodic callbacks |
668 | increase efficiency of loop iterations. |
736 | to increase efficiency of loop iterations (or to increase power-saving |
|
|
737 | opportunities). |
669 | |
738 | |
670 | The background is that sometimes your program runs just fast enough to |
739 | The idea is that sometimes your program runs just fast enough to handle |
671 | handle one (or very few) event(s) per loop iteration. While this makes |
740 | one (or very few) event(s) per loop iteration. While this makes the |
672 | the program responsive, it also wastes a lot of CPU time to poll for new |
741 | program responsive, it also wastes a lot of CPU time to poll for new |
673 | events, especially with backends like C<select ()> which have a high |
742 | events, especially with backends like C<select ()> which have a high |
674 | overhead for the actual polling but can deliver many events at once. |
743 | overhead for the actual polling but can deliver many events at once. |
675 | |
744 | |
676 | By setting a higher I<io collect interval> you allow libev to spend more |
745 | By setting a higher I<io collect interval> you allow libev to spend more |
677 | time collecting I/O events, so you can handle more events per iteration, |
746 | time collecting I/O events, so you can handle more events per iteration, |
… | |
… | |
679 | C<ev_timer>) will be not affected. Setting this to a non-null value will |
748 | C<ev_timer>) will be not affected. Setting this to a non-null value will |
680 | introduce an additional C<ev_sleep ()> call into most loop iterations. |
749 | introduce an additional C<ev_sleep ()> call into most loop iterations. |
681 | |
750 | |
682 | Likewise, by setting a higher I<timeout collect interval> you allow libev |
751 | Likewise, by setting a higher I<timeout collect interval> you allow libev |
683 | to spend more time collecting timeouts, at the expense of increased |
752 | to spend more time collecting timeouts, at the expense of increased |
684 | latency (the watcher callback will be called later). C<ev_io> watchers |
753 | latency/jitter/inexactness (the watcher callback will be called |
685 | will not be affected. Setting this to a non-null value will not introduce |
754 | later). C<ev_io> watchers will not be affected. Setting this to a non-null |
686 | any overhead in libev. |
755 | value will not introduce any overhead in libev. |
687 | |
756 | |
688 | Many (busy) programs can usually benefit by setting the io collect |
757 | Many (busy) programs can usually benefit by setting the I/O collect |
689 | interval to a value near C<0.1> or so, which is often enough for |
758 | interval to a value near C<0.1> or so, which is often enough for |
690 | interactive servers (of course not for games), likewise for timeouts. It |
759 | interactive servers (of course not for games), likewise for timeouts. It |
691 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
760 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
692 | as this approsaches the timing granularity of most systems. |
761 | as this approaches the timing granularity of most systems. |
|
|
762 | |
|
|
763 | Setting the I<timeout collect interval> can improve the opportunity for |
|
|
764 | saving power, as the program will "bundle" timer callback invocations that |
|
|
765 | are "near" in time together, by delaying some, thus reducing the number of |
|
|
766 | times the process sleeps and wakes up again. Another useful technique to |
|
|
767 | reduce iterations/wake-ups is to use C<ev_periodic> watchers and make sure |
|
|
768 | they fire on, say, one-second boundaries only. |
|
|
769 | |
|
|
770 | =item ev_loop_verify (loop) |
|
|
771 | |
|
|
772 | This function only does something when C<EV_VERIFY> support has been |
|
|
773 | compiled in. which is the default for non-minimal builds. It tries to go |
|
|
774 | through all internal structures and checks them for validity. If anything |
|
|
775 | is found to be inconsistent, it will print an error message to standard |
|
|
776 | error and call C<abort ()>. |
|
|
777 | |
|
|
778 | This can be used to catch bugs inside libev itself: under normal |
|
|
779 | circumstances, this function will never abort as of course libev keeps its |
|
|
780 | data structures consistent. |
693 | |
781 | |
694 | =back |
782 | =back |
695 | |
783 | |
696 | |
784 | |
697 | =head1 ANATOMY OF A WATCHER |
785 | =head1 ANATOMY OF A WATCHER |
698 | |
786 | |
699 | A watcher is a structure that you create and register to record your |
787 | A watcher is a structure that you create and register to record your |
700 | interest in some event. For instance, if you want to wait for STDIN to |
788 | interest in some event. For instance, if you want to wait for STDIN to |
701 | become readable, you would create an C<ev_io> watcher for that: |
789 | become readable, you would create an C<ev_io> watcher for that: |
702 | |
790 | |
703 | static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
791 | static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
704 | { |
792 | { |
705 | ev_io_stop (w); |
793 | ev_io_stop (w); |
706 | ev_unloop (loop, EVUNLOOP_ALL); |
794 | ev_unloop (loop, EVUNLOOP_ALL); |
707 | } |
795 | } |
708 | |
796 | |
709 | struct ev_loop *loop = ev_default_loop (0); |
797 | struct ev_loop *loop = ev_default_loop (0); |
710 | struct ev_io stdin_watcher; |
798 | struct ev_io stdin_watcher; |
711 | ev_init (&stdin_watcher, my_cb); |
799 | ev_init (&stdin_watcher, my_cb); |
712 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
800 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
713 | ev_io_start (loop, &stdin_watcher); |
801 | ev_io_start (loop, &stdin_watcher); |
714 | ev_loop (loop, 0); |
802 | ev_loop (loop, 0); |
715 | |
803 | |
716 | As you can see, you are responsible for allocating the memory for your |
804 | As you can see, you are responsible for allocating the memory for your |
717 | watcher structures (and it is usually a bad idea to do this on the stack, |
805 | watcher structures (and it is usually a bad idea to do this on the stack, |
718 | although this can sometimes be quite valid). |
806 | although this can sometimes be quite valid). |
719 | |
807 | |
720 | Each watcher structure must be initialised by a call to C<ev_init |
808 | Each watcher structure must be initialised by a call to C<ev_init |
721 | (watcher *, callback)>, which expects a callback to be provided. This |
809 | (watcher *, callback)>, which expects a callback to be provided. This |
722 | callback gets invoked each time the event occurs (or, in the case of io |
810 | callback gets invoked each time the event occurs (or, in the case of I/O |
723 | watchers, each time the event loop detects that the file descriptor given |
811 | watchers, each time the event loop detects that the file descriptor given |
724 | is readable and/or writable). |
812 | is readable and/or writable). |
725 | |
813 | |
726 | Each watcher type has its own C<< ev_<type>_set (watcher *, ...) >> macro |
814 | Each watcher type has its own C<< ev_<type>_set (watcher *, ...) >> macro |
727 | with arguments specific to this watcher type. There is also a macro |
815 | with arguments specific to this watcher type. There is also a macro |
… | |
… | |
803 | |
891 | |
804 | The given async watcher has been asynchronously notified (see C<ev_async>). |
892 | The given async watcher has been asynchronously notified (see C<ev_async>). |
805 | |
893 | |
806 | =item C<EV_ERROR> |
894 | =item C<EV_ERROR> |
807 | |
895 | |
808 | An unspecified error has occured, the watcher has been stopped. This might |
896 | An unspecified error has occurred, the watcher has been stopped. This might |
809 | happen because the watcher could not be properly started because libev |
897 | happen because the watcher could not be properly started because libev |
810 | ran out of memory, a file descriptor was found to be closed or any other |
898 | ran out of memory, a file descriptor was found to be closed or any other |
|
|
899 | problem. Libev considers these application bugs. |
|
|
900 | |
811 | problem. You best act on it by reporting the problem and somehow coping |
901 | You best act on it by reporting the problem and somehow coping with the |
812 | with the watcher being stopped. |
902 | watcher being stopped. Note that well-written programs should not receive |
|
|
903 | an error ever, so when your watcher receives it, this usually indicates a |
|
|
904 | bug in your program. |
813 | |
905 | |
814 | Libev will usually signal a few "dummy" events together with an error, |
906 | Libev will usually signal a few "dummy" events together with an error, for |
815 | for example it might indicate that a fd is readable or writable, and if |
907 | example it might indicate that a fd is readable or writable, and if your |
816 | your callbacks is well-written it can just attempt the operation and cope |
908 | callbacks is well-written it can just attempt the operation and cope with |
817 | with the error from read() or write(). This will not work in multithreaded |
909 | the error from read() or write(). This will not work in multi-threaded |
818 | programs, though, so beware. |
910 | programs, though, as the fd could already be closed and reused for another |
|
|
911 | thing, so beware. |
819 | |
912 | |
820 | =back |
913 | =back |
821 | |
914 | |
822 | =head2 GENERIC WATCHER FUNCTIONS |
915 | =head2 GENERIC WATCHER FUNCTIONS |
823 | |
916 | |
… | |
… | |
839 | (or never started) and there are no pending events outstanding. |
932 | (or never started) and there are no pending events outstanding. |
840 | |
933 | |
841 | The callback is always of type C<void (*)(ev_loop *loop, ev_TYPE *watcher, |
934 | The callback is always of type C<void (*)(ev_loop *loop, ev_TYPE *watcher, |
842 | int revents)>. |
935 | int revents)>. |
843 | |
936 | |
|
|
937 | Example: Initialise an C<ev_io> watcher in two steps. |
|
|
938 | |
|
|
939 | ev_io w; |
|
|
940 | ev_init (&w, my_cb); |
|
|
941 | ev_io_set (&w, STDIN_FILENO, EV_READ); |
|
|
942 | |
844 | =item C<ev_TYPE_set> (ev_TYPE *, [args]) |
943 | =item C<ev_TYPE_set> (ev_TYPE *, [args]) |
845 | |
944 | |
846 | This macro initialises the type-specific parts of a watcher. You need to |
945 | This macro initialises the type-specific parts of a watcher. You need to |
847 | call C<ev_init> at least once before you call this macro, but you can |
946 | call C<ev_init> at least once before you call this macro, but you can |
848 | call C<ev_TYPE_set> any number of times. You must not, however, call this |
947 | call C<ev_TYPE_set> any number of times. You must not, however, call this |
… | |
… | |
850 | difference to the C<ev_init> macro). |
949 | difference to the C<ev_init> macro). |
851 | |
950 | |
852 | Although some watcher types do not have type-specific arguments |
951 | Although some watcher types do not have type-specific arguments |
853 | (e.g. C<ev_prepare>) you still need to call its C<set> macro. |
952 | (e.g. C<ev_prepare>) you still need to call its C<set> macro. |
854 | |
953 | |
|
|
954 | See C<ev_init>, above, for an example. |
|
|
955 | |
855 | =item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args]) |
956 | =item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args]) |
856 | |
957 | |
857 | This convinience macro rolls both C<ev_init> and C<ev_TYPE_set> macro |
958 | This convenience macro rolls both C<ev_init> and C<ev_TYPE_set> macro |
858 | calls into a single call. This is the most convinient method to initialise |
959 | calls into a single call. This is the most convenient method to initialise |
859 | a watcher. The same limitations apply, of course. |
960 | a watcher. The same limitations apply, of course. |
|
|
961 | |
|
|
962 | Example: Initialise and set an C<ev_io> watcher in one step. |
|
|
963 | |
|
|
964 | ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
860 | |
965 | |
861 | =item C<ev_TYPE_start> (loop *, ev_TYPE *watcher) |
966 | =item C<ev_TYPE_start> (loop *, ev_TYPE *watcher) |
862 | |
967 | |
863 | Starts (activates) the given watcher. Only active watchers will receive |
968 | Starts (activates) the given watcher. Only active watchers will receive |
864 | events. If the watcher is already active nothing will happen. |
969 | events. If the watcher is already active nothing will happen. |
865 | |
970 | |
|
|
971 | Example: Start the C<ev_io> watcher that is being abused as example in this |
|
|
972 | whole section. |
|
|
973 | |
|
|
974 | ev_io_start (EV_DEFAULT_UC, &w); |
|
|
975 | |
866 | =item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher) |
976 | =item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher) |
867 | |
977 | |
868 | Stops the given watcher again (if active) and clears the pending |
978 | Stops the given watcher if active, and clears the pending status (whether |
|
|
979 | the watcher was active or not). |
|
|
980 | |
869 | status. It is possible that stopped watchers are pending (for example, |
981 | It is possible that stopped watchers are pending - for example, |
870 | non-repeating timers are being stopped when they become pending), but |
982 | non-repeating timers are being stopped when they become pending - but |
871 | C<ev_TYPE_stop> ensures that the watcher is neither active nor pending. If |
983 | calling C<ev_TYPE_stop> ensures that the watcher is neither active nor |
872 | you want to free or reuse the memory used by the watcher it is therefore a |
984 | pending. If you want to free or reuse the memory used by the watcher it is |
873 | good idea to always call its C<ev_TYPE_stop> function. |
985 | therefore a good idea to always call its C<ev_TYPE_stop> function. |
874 | |
986 | |
875 | =item bool ev_is_active (ev_TYPE *watcher) |
987 | =item bool ev_is_active (ev_TYPE *watcher) |
876 | |
988 | |
877 | Returns a true value iff the watcher is active (i.e. it has been started |
989 | Returns a true value iff the watcher is active (i.e. it has been started |
878 | and not yet been stopped). As long as a watcher is active you must not modify |
990 | and not yet been stopped). As long as a watcher is active you must not modify |
… | |
… | |
926 | |
1038 | |
927 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
1039 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
928 | |
1040 | |
929 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
1041 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
930 | C<loop> nor C<revents> need to be valid as long as the watcher callback |
1042 | C<loop> nor C<revents> need to be valid as long as the watcher callback |
931 | can deal with that fact. |
1043 | can deal with that fact, as both are simply passed through to the |
|
|
1044 | callback. |
932 | |
1045 | |
933 | =item int ev_clear_pending (loop, ev_TYPE *watcher) |
1046 | =item int ev_clear_pending (loop, ev_TYPE *watcher) |
934 | |
1047 | |
935 | If the watcher is pending, this function returns clears its pending status |
1048 | If the watcher is pending, this function clears its pending status and |
936 | and returns its C<revents> bitset (as if its callback was invoked). If the |
1049 | returns its C<revents> bitset (as if its callback was invoked). If the |
937 | watcher isn't pending it does nothing and returns C<0>. |
1050 | watcher isn't pending it does nothing and returns C<0>. |
938 | |
1051 | |
|
|
1052 | Sometimes it can be useful to "poll" a watcher instead of waiting for its |
|
|
1053 | callback to be invoked, which can be accomplished with this function. |
|
|
1054 | |
939 | =back |
1055 | =back |
940 | |
1056 | |
941 | |
1057 | |
942 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
1058 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
943 | |
1059 | |
944 | Each watcher has, by default, a member C<void *data> that you can change |
1060 | Each watcher has, by default, a member C<void *data> that you can change |
945 | and read at any time, libev will completely ignore it. This can be used |
1061 | and read at any time: libev will completely ignore it. This can be used |
946 | to associate arbitrary data with your watcher. If you need more data and |
1062 | to associate arbitrary data with your watcher. If you need more data and |
947 | don't want to allocate memory and store a pointer to it in that data |
1063 | don't want to allocate memory and store a pointer to it in that data |
948 | member, you can also "subclass" the watcher type and provide your own |
1064 | member, you can also "subclass" the watcher type and provide your own |
949 | data: |
1065 | data: |
950 | |
1066 | |
951 | struct my_io |
1067 | struct my_io |
952 | { |
1068 | { |
953 | struct ev_io io; |
1069 | struct ev_io io; |
954 | int otherfd; |
1070 | int otherfd; |
955 | void *somedata; |
1071 | void *somedata; |
956 | struct whatever *mostinteresting; |
1072 | struct whatever *mostinteresting; |
957 | } |
1073 | }; |
|
|
1074 | |
|
|
1075 | ... |
|
|
1076 | struct my_io w; |
|
|
1077 | ev_io_init (&w.io, my_cb, fd, EV_READ); |
958 | |
1078 | |
959 | And since your callback will be called with a pointer to the watcher, you |
1079 | And since your callback will be called with a pointer to the watcher, you |
960 | can cast it back to your own type: |
1080 | can cast it back to your own type: |
961 | |
1081 | |
962 | static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents) |
1082 | static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents) |
963 | { |
1083 | { |
964 | struct my_io *w = (struct my_io *)w_; |
1084 | struct my_io *w = (struct my_io *)w_; |
965 | ... |
1085 | ... |
966 | } |
1086 | } |
967 | |
1087 | |
968 | More interesting and less C-conformant ways of casting your callback type |
1088 | More interesting and less C-conformant ways of casting your callback type |
969 | instead have been omitted. |
1089 | instead have been omitted. |
970 | |
1090 | |
971 | Another common scenario is having some data structure with multiple |
1091 | Another common scenario is to use some data structure with multiple |
972 | watchers: |
1092 | embedded watchers: |
973 | |
1093 | |
974 | struct my_biggy |
1094 | struct my_biggy |
975 | { |
1095 | { |
976 | int some_data; |
1096 | int some_data; |
977 | ev_timer t1; |
1097 | ev_timer t1; |
978 | ev_timer t2; |
1098 | ev_timer t2; |
979 | } |
1099 | } |
980 | |
1100 | |
981 | In this case getting the pointer to C<my_biggy> is a bit more complicated, |
1101 | In this case getting the pointer to C<my_biggy> is a bit more |
982 | you need to use C<offsetof>: |
1102 | complicated: Either you store the address of your C<my_biggy> struct |
|
|
1103 | in the C<data> member of the watcher (for woozies), or you need to use |
|
|
1104 | some pointer arithmetic using C<offsetof> inside your watchers (for real |
|
|
1105 | programmers): |
983 | |
1106 | |
984 | #include <stddef.h> |
1107 | #include <stddef.h> |
985 | |
1108 | |
986 | static void |
1109 | static void |
987 | t1_cb (EV_P_ struct ev_timer *w, int revents) |
1110 | t1_cb (EV_P_ struct ev_timer *w, int revents) |
988 | { |
1111 | { |
989 | struct my_biggy big = (struct my_biggy * |
1112 | struct my_biggy big = (struct my_biggy * |
990 | (((char *)w) - offsetof (struct my_biggy, t1)); |
1113 | (((char *)w) - offsetof (struct my_biggy, t1)); |
991 | } |
1114 | } |
992 | |
1115 | |
993 | static void |
1116 | static void |
994 | t2_cb (EV_P_ struct ev_timer *w, int revents) |
1117 | t2_cb (EV_P_ struct ev_timer *w, int revents) |
995 | { |
1118 | { |
996 | struct my_biggy big = (struct my_biggy * |
1119 | struct my_biggy big = (struct my_biggy * |
997 | (((char *)w) - offsetof (struct my_biggy, t2)); |
1120 | (((char *)w) - offsetof (struct my_biggy, t2)); |
998 | } |
1121 | } |
999 | |
1122 | |
1000 | |
1123 | |
1001 | =head1 WATCHER TYPES |
1124 | =head1 WATCHER TYPES |
1002 | |
1125 | |
1003 | This section describes each watcher in detail, but will not repeat |
1126 | This section describes each watcher in detail, but will not repeat |
… | |
… | |
1027 | In general you can register as many read and/or write event watchers per |
1150 | In general you can register as many read and/or write event watchers per |
1028 | fd as you want (as long as you don't confuse yourself). Setting all file |
1151 | fd as you want (as long as you don't confuse yourself). Setting all file |
1029 | descriptors to non-blocking mode is also usually a good idea (but not |
1152 | descriptors to non-blocking mode is also usually a good idea (but not |
1030 | required if you know what you are doing). |
1153 | required if you know what you are doing). |
1031 | |
1154 | |
1032 | If you must do this, then force the use of a known-to-be-good backend |
1155 | If you cannot use non-blocking mode, then force the use of a |
1033 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
1156 | known-to-be-good backend (at the time of this writing, this includes only |
1034 | C<EVBACKEND_POLL>). |
1157 | C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). |
1035 | |
1158 | |
1036 | Another thing you have to watch out for is that it is quite easy to |
1159 | Another thing you have to watch out for is that it is quite easy to |
1037 | receive "spurious" readyness notifications, that is your callback might |
1160 | receive "spurious" readiness notifications, that is your callback might |
1038 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1161 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1039 | because there is no data. Not only are some backends known to create a |
1162 | because there is no data. Not only are some backends known to create a |
1040 | lot of those (for example solaris ports), it is very easy to get into |
1163 | lot of those (for example Solaris ports), it is very easy to get into |
1041 | this situation even with a relatively standard program structure. Thus |
1164 | this situation even with a relatively standard program structure. Thus |
1042 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
1165 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
1043 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
1166 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
1044 | |
1167 | |
1045 | If you cannot run the fd in non-blocking mode (for example you should not |
1168 | If you cannot run the fd in non-blocking mode (for example you should |
1046 | play around with an Xlib connection), then you have to seperately re-test |
1169 | not play around with an Xlib connection), then you have to separately |
1047 | whether a file descriptor is really ready with a known-to-be good interface |
1170 | re-test whether a file descriptor is really ready with a known-to-be good |
1048 | such as poll (fortunately in our Xlib example, Xlib already does this on |
1171 | interface such as poll (fortunately in our Xlib example, Xlib already |
1049 | its own, so its quite safe to use). |
1172 | does this on its own, so its quite safe to use). Some people additionally |
|
|
1173 | use C<SIGALRM> and an interval timer, just to be sure you won't block |
|
|
1174 | indefinitely. |
|
|
1175 | |
|
|
1176 | But really, best use non-blocking mode. |
1050 | |
1177 | |
1051 | =head3 The special problem of disappearing file descriptors |
1178 | =head3 The special problem of disappearing file descriptors |
1052 | |
1179 | |
1053 | Some backends (e.g. kqueue, epoll) need to be told about closing a file |
1180 | Some backends (e.g. kqueue, epoll) need to be told about closing a file |
1054 | descriptor (either by calling C<close> explicitly or by any other means, |
1181 | descriptor (either due to calling C<close> explicitly or any other means, |
1055 | such as C<dup>). The reason is that you register interest in some file |
1182 | such as C<dup2>). The reason is that you register interest in some file |
1056 | descriptor, but when it goes away, the operating system will silently drop |
1183 | descriptor, but when it goes away, the operating system will silently drop |
1057 | this interest. If another file descriptor with the same number then is |
1184 | this interest. If another file descriptor with the same number then is |
1058 | registered with libev, there is no efficient way to see that this is, in |
1185 | registered with libev, there is no efficient way to see that this is, in |
1059 | fact, a different file descriptor. |
1186 | fact, a different file descriptor. |
1060 | |
1187 | |
… | |
… | |
1091 | enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or |
1218 | enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or |
1092 | C<EVBACKEND_POLL>. |
1219 | C<EVBACKEND_POLL>. |
1093 | |
1220 | |
1094 | =head3 The special problem of SIGPIPE |
1221 | =head3 The special problem of SIGPIPE |
1095 | |
1222 | |
1096 | While not really specific to libev, it is easy to forget about SIGPIPE: |
1223 | While not really specific to libev, it is easy to forget about C<SIGPIPE>: |
1097 | when reading from a pipe whose other end has been closed, your program |
1224 | when writing to a pipe whose other end has been closed, your program gets |
1098 | gets send a SIGPIPE, which, by default, aborts your program. For most |
1225 | sent a SIGPIPE, which, by default, aborts your program. For most programs |
1099 | programs this is sensible behaviour, for daemons, this is usually |
1226 | this is sensible behaviour, for daemons, this is usually undesirable. |
1100 | undesirable. |
|
|
1101 | |
1227 | |
1102 | So when you encounter spurious, unexplained daemon exits, make sure you |
1228 | So when you encounter spurious, unexplained daemon exits, make sure you |
1103 | ignore SIGPIPE (and maybe make sure you log the exit status of your daemon |
1229 | ignore SIGPIPE (and maybe make sure you log the exit status of your daemon |
1104 | somewhere, as that would have given you a big clue). |
1230 | somewhere, as that would have given you a big clue). |
1105 | |
1231 | |
… | |
… | |
1111 | =item ev_io_init (ev_io *, callback, int fd, int events) |
1237 | =item ev_io_init (ev_io *, callback, int fd, int events) |
1112 | |
1238 | |
1113 | =item ev_io_set (ev_io *, int fd, int events) |
1239 | =item ev_io_set (ev_io *, int fd, int events) |
1114 | |
1240 | |
1115 | Configures an C<ev_io> watcher. The C<fd> is the file descriptor to |
1241 | Configures an C<ev_io> watcher. The C<fd> is the file descriptor to |
1116 | rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or |
1242 | receive events for and C<events> is either C<EV_READ>, C<EV_WRITE> or |
1117 | C<EV_READ | EV_WRITE> to receive the given events. |
1243 | C<EV_READ | EV_WRITE>, to express the desire to receive the given events. |
1118 | |
1244 | |
1119 | =item int fd [read-only] |
1245 | =item int fd [read-only] |
1120 | |
1246 | |
1121 | The file descriptor being watched. |
1247 | The file descriptor being watched. |
1122 | |
1248 | |
… | |
… | |
1130 | |
1256 | |
1131 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
1257 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
1132 | readable, but only once. Since it is likely line-buffered, you could |
1258 | readable, but only once. Since it is likely line-buffered, you could |
1133 | attempt to read a whole line in the callback. |
1259 | attempt to read a whole line in the callback. |
1134 | |
1260 | |
1135 | static void |
1261 | static void |
1136 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1262 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1137 | { |
1263 | { |
1138 | ev_io_stop (loop, w); |
1264 | ev_io_stop (loop, w); |
1139 | .. read from stdin here (or from w->fd) and haqndle any I/O errors |
1265 | .. read from stdin here (or from w->fd) and handle any I/O errors |
1140 | } |
1266 | } |
1141 | |
1267 | |
1142 | ... |
1268 | ... |
1143 | struct ev_loop *loop = ev_default_init (0); |
1269 | struct ev_loop *loop = ev_default_init (0); |
1144 | struct ev_io stdin_readable; |
1270 | struct ev_io stdin_readable; |
1145 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1271 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1146 | ev_io_start (loop, &stdin_readable); |
1272 | ev_io_start (loop, &stdin_readable); |
1147 | ev_loop (loop, 0); |
1273 | ev_loop (loop, 0); |
1148 | |
1274 | |
1149 | |
1275 | |
1150 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
1276 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
1151 | |
1277 | |
1152 | Timer watchers are simple relative timers that generate an event after a |
1278 | Timer watchers are simple relative timers that generate an event after a |
1153 | given time, and optionally repeating in regular intervals after that. |
1279 | given time, and optionally repeating in regular intervals after that. |
1154 | |
1280 | |
1155 | The timers are based on real time, that is, if you register an event that |
1281 | The timers are based on real time, that is, if you register an event that |
1156 | times out after an hour and you reset your system clock to last years |
1282 | times out after an hour and you reset your system clock to January last |
1157 | time, it will still time out after (roughly) and hour. "Roughly" because |
1283 | year, it will still time out after (roughly) one hour. "Roughly" because |
1158 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1284 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1159 | monotonic clock option helps a lot here). |
1285 | monotonic clock option helps a lot here). |
|
|
1286 | |
|
|
1287 | The callback is guaranteed to be invoked only I<after> its timeout has |
|
|
1288 | passed, but if multiple timers become ready during the same loop iteration |
|
|
1289 | then order of execution is undefined. |
|
|
1290 | |
|
|
1291 | =head3 The special problem of time updates |
|
|
1292 | |
|
|
1293 | Establishing the current time is a costly operation (it usually takes at |
|
|
1294 | least two system calls): EV therefore updates its idea of the current |
|
|
1295 | time only before and after C<ev_loop> collects new events, which causes a |
|
|
1296 | growing difference between C<ev_now ()> and C<ev_time ()> when handling |
|
|
1297 | lots of events in one iteration. |
1160 | |
1298 | |
1161 | The relative timeouts are calculated relative to the C<ev_now ()> |
1299 | The relative timeouts are calculated relative to the C<ev_now ()> |
1162 | time. This is usually the right thing as this timestamp refers to the time |
1300 | time. This is usually the right thing as this timestamp refers to the time |
1163 | of the event triggering whatever timeout you are modifying/starting. If |
1301 | of the event triggering whatever timeout you are modifying/starting. If |
1164 | you suspect event processing to be delayed and you I<need> to base the timeout |
1302 | you suspect event processing to be delayed and you I<need> to base the |
1165 | on the current time, use something like this to adjust for this: |
1303 | timeout on the current time, use something like this to adjust for this: |
1166 | |
1304 | |
1167 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
1305 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
1168 | |
1306 | |
1169 | The callback is guarenteed to be invoked only when its timeout has passed, |
1307 | If the event loop is suspended for a long time, you can also force an |
1170 | but if multiple timers become ready during the same loop iteration then |
1308 | update of the time returned by C<ev_now ()> by calling C<ev_now_update |
1171 | order of execution is undefined. |
1309 | ()>. |
1172 | |
1310 | |
1173 | =head3 Watcher-Specific Functions and Data Members |
1311 | =head3 Watcher-Specific Functions and Data Members |
1174 | |
1312 | |
1175 | =over 4 |
1313 | =over 4 |
1176 | |
1314 | |
1177 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
1315 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
1178 | |
1316 | |
1179 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
1317 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
1180 | |
1318 | |
1181 | Configure the timer to trigger after C<after> seconds. If C<repeat> is |
1319 | Configure the timer to trigger after C<after> seconds. If C<repeat> |
1182 | C<0.>, then it will automatically be stopped. If it is positive, then the |
1320 | is C<0.>, then it will automatically be stopped once the timeout is |
1183 | timer will automatically be configured to trigger again C<repeat> seconds |
1321 | reached. If it is positive, then the timer will automatically be |
1184 | later, again, and again, until stopped manually. |
1322 | configured to trigger again C<repeat> seconds later, again, and again, |
|
|
1323 | until stopped manually. |
1185 | |
1324 | |
1186 | The timer itself will do a best-effort at avoiding drift, that is, if you |
1325 | The timer itself will do a best-effort at avoiding drift, that is, if |
1187 | configure a timer to trigger every 10 seconds, then it will trigger at |
1326 | you configure a timer to trigger every 10 seconds, then it will normally |
1188 | exactly 10 second intervals. If, however, your program cannot keep up with |
1327 | trigger at exactly 10 second intervals. If, however, your program cannot |
1189 | the timer (because it takes longer than those 10 seconds to do stuff) the |
1328 | keep up with the timer (because it takes longer than those 10 seconds to |
1190 | timer will not fire more than once per event loop iteration. |
1329 | do stuff) the timer will not fire more than once per event loop iteration. |
1191 | |
1330 | |
1192 | =item ev_timer_again (loop, ev_timer *) |
1331 | =item ev_timer_again (loop, ev_timer *) |
1193 | |
1332 | |
1194 | This will act as if the timer timed out and restart it again if it is |
1333 | This will act as if the timer timed out and restart it again if it is |
1195 | repeating. The exact semantics are: |
1334 | repeating. The exact semantics are: |
1196 | |
1335 | |
1197 | If the timer is pending, its pending status is cleared. |
1336 | If the timer is pending, its pending status is cleared. |
1198 | |
1337 | |
1199 | If the timer is started but nonrepeating, stop it (as if it timed out). |
1338 | If the timer is started but non-repeating, stop it (as if it timed out). |
1200 | |
1339 | |
1201 | If the timer is repeating, either start it if necessary (with the |
1340 | If the timer is repeating, either start it if necessary (with the |
1202 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1341 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1203 | |
1342 | |
1204 | This sounds a bit complicated, but here is a useful and typical |
1343 | This sounds a bit complicated, but here is a useful and typical |
1205 | example: Imagine you have a tcp connection and you want a so-called idle |
1344 | example: Imagine you have a TCP connection and you want a so-called idle |
1206 | timeout, that is, you want to be called when there have been, say, 60 |
1345 | timeout, that is, you want to be called when there have been, say, 60 |
1207 | seconds of inactivity on the socket. The easiest way to do this is to |
1346 | seconds of inactivity on the socket. The easiest way to do this is to |
1208 | configure an C<ev_timer> with a C<repeat> value of C<60> and then call |
1347 | configure an C<ev_timer> with a C<repeat> value of C<60> and then call |
1209 | C<ev_timer_again> each time you successfully read or write some data. If |
1348 | C<ev_timer_again> each time you successfully read or write some data. If |
1210 | you go into an idle state where you do not expect data to travel on the |
1349 | you go into an idle state where you do not expect data to travel on the |
… | |
… | |
1224 | ev_timer_again (loop, timer); |
1363 | ev_timer_again (loop, timer); |
1225 | |
1364 | |
1226 | This is more slightly efficient then stopping/starting the timer each time |
1365 | This is more slightly efficient then stopping/starting the timer each time |
1227 | you want to modify its timeout value. |
1366 | you want to modify its timeout value. |
1228 | |
1367 | |
|
|
1368 | Note, however, that it is often even more efficient to remember the |
|
|
1369 | time of the last activity and let the timer time-out naturally. In the |
|
|
1370 | callback, you then check whether the time-out is real, or, if there was |
|
|
1371 | some activity, you reschedule the watcher to time-out in "last_activity + |
|
|
1372 | timeout - ev_now ()" seconds. |
|
|
1373 | |
1229 | =item ev_tstamp repeat [read-write] |
1374 | =item ev_tstamp repeat [read-write] |
1230 | |
1375 | |
1231 | The current C<repeat> value. Will be used each time the watcher times out |
1376 | The current C<repeat> value. Will be used each time the watcher times out |
1232 | or C<ev_timer_again> is called and determines the next timeout (if any), |
1377 | or C<ev_timer_again> is called, and determines the next timeout (if any), |
1233 | which is also when any modifications are taken into account. |
1378 | which is also when any modifications are taken into account. |
1234 | |
1379 | |
1235 | =back |
1380 | =back |
1236 | |
1381 | |
1237 | =head3 Examples |
1382 | =head3 Examples |
1238 | |
1383 | |
1239 | Example: Create a timer that fires after 60 seconds. |
1384 | Example: Create a timer that fires after 60 seconds. |
1240 | |
1385 | |
1241 | static void |
1386 | static void |
1242 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1387 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1243 | { |
1388 | { |
1244 | .. one minute over, w is actually stopped right here |
1389 | .. one minute over, w is actually stopped right here |
1245 | } |
1390 | } |
1246 | |
1391 | |
1247 | struct ev_timer mytimer; |
1392 | struct ev_timer mytimer; |
1248 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
1393 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
1249 | ev_timer_start (loop, &mytimer); |
1394 | ev_timer_start (loop, &mytimer); |
1250 | |
1395 | |
1251 | Example: Create a timeout timer that times out after 10 seconds of |
1396 | Example: Create a timeout timer that times out after 10 seconds of |
1252 | inactivity. |
1397 | inactivity. |
1253 | |
1398 | |
1254 | static void |
1399 | static void |
1255 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1400 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1256 | { |
1401 | { |
1257 | .. ten seconds without any activity |
1402 | .. ten seconds without any activity |
1258 | } |
1403 | } |
1259 | |
1404 | |
1260 | struct ev_timer mytimer; |
1405 | struct ev_timer mytimer; |
1261 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1406 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1262 | ev_timer_again (&mytimer); /* start timer */ |
1407 | ev_timer_again (&mytimer); /* start timer */ |
1263 | ev_loop (loop, 0); |
1408 | ev_loop (loop, 0); |
1264 | |
1409 | |
1265 | // and in some piece of code that gets executed on any "activity": |
1410 | // and in some piece of code that gets executed on any "activity": |
1266 | // reset the timeout to start ticking again at 10 seconds |
1411 | // reset the timeout to start ticking again at 10 seconds |
1267 | ev_timer_again (&mytimer); |
1412 | ev_timer_again (&mytimer); |
1268 | |
1413 | |
1269 | |
1414 | |
1270 | =head2 C<ev_periodic> - to cron or not to cron? |
1415 | =head2 C<ev_periodic> - to cron or not to cron? |
1271 | |
1416 | |
1272 | Periodic watchers are also timers of a kind, but they are very versatile |
1417 | Periodic watchers are also timers of a kind, but they are very versatile |
1273 | (and unfortunately a bit complex). |
1418 | (and unfortunately a bit complex). |
1274 | |
1419 | |
1275 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
1420 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
1276 | but on wallclock time (absolute time). You can tell a periodic watcher |
1421 | but on wall clock time (absolute time). You can tell a periodic watcher |
1277 | to trigger "at" some specific point in time. For example, if you tell a |
1422 | to trigger after some specific point in time. For example, if you tell a |
1278 | periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now () |
1423 | periodic watcher to trigger in 10 seconds (by specifying e.g. C<ev_now () |
1279 | + 10.>) and then reset your system clock to the last year, then it will |
1424 | + 10.>, that is, an absolute time not a delay) and then reset your system |
|
|
1425 | clock to January of the previous year, then it will take more than year |
1280 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
1426 | to trigger the event (unlike an C<ev_timer>, which would still trigger |
1281 | roughly 10 seconds later). |
1427 | roughly 10 seconds later as it uses a relative timeout). |
1282 | |
1428 | |
1283 | They can also be used to implement vastly more complex timers, such as |
1429 | C<ev_periodic>s can also be used to implement vastly more complex timers, |
1284 | triggering an event on each midnight, local time or other, complicated, |
1430 | such as triggering an event on each "midnight, local time", or other |
1285 | rules. |
1431 | complicated rules. |
1286 | |
1432 | |
1287 | As with timers, the callback is guarenteed to be invoked only when the |
1433 | As with timers, the callback is guaranteed to be invoked only when the |
1288 | time (C<at>) has been passed, but if multiple periodic timers become ready |
1434 | time (C<at>) has passed, but if multiple periodic timers become ready |
1289 | during the same loop iteration then order of execution is undefined. |
1435 | during the same loop iteration, then order of execution is undefined. |
1290 | |
1436 | |
1291 | =head3 Watcher-Specific Functions and Data Members |
1437 | =head3 Watcher-Specific Functions and Data Members |
1292 | |
1438 | |
1293 | =over 4 |
1439 | =over 4 |
1294 | |
1440 | |
1295 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
1441 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
1296 | |
1442 | |
1297 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
1443 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
1298 | |
1444 | |
1299 | Lots of arguments, lets sort it out... There are basically three modes of |
1445 | Lots of arguments, lets sort it out... There are basically three modes of |
1300 | operation, and we will explain them from simplest to complex: |
1446 | operation, and we will explain them from simplest to most complex: |
1301 | |
1447 | |
1302 | =over 4 |
1448 | =over 4 |
1303 | |
1449 | |
1304 | =item * absolute timer (at = time, interval = reschedule_cb = 0) |
1450 | =item * absolute timer (at = time, interval = reschedule_cb = 0) |
1305 | |
1451 | |
1306 | In this configuration the watcher triggers an event at the wallclock time |
1452 | In this configuration the watcher triggers an event after the wall clock |
1307 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
1453 | time C<at> has passed. It will not repeat and will not adjust when a time |
1308 | that is, if it is to be run at January 1st 2011 then it will run when the |
1454 | jump occurs, that is, if it is to be run at January 1st 2011 then it will |
1309 | system time reaches or surpasses this time. |
1455 | only run when the system clock reaches or surpasses this time. |
1310 | |
1456 | |
1311 | =item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
1457 | =item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
1312 | |
1458 | |
1313 | In this mode the watcher will always be scheduled to time out at the next |
1459 | In this mode the watcher will always be scheduled to time out at the next |
1314 | C<at + N * interval> time (for some integer N, which can also be negative) |
1460 | C<at + N * interval> time (for some integer N, which can also be negative) |
1315 | and then repeat, regardless of any time jumps. |
1461 | and then repeat, regardless of any time jumps. |
1316 | |
1462 | |
1317 | This can be used to create timers that do not drift with respect to system |
1463 | This can be used to create timers that do not drift with respect to the |
1318 | time: |
1464 | system clock, for example, here is a C<ev_periodic> that triggers each |
|
|
1465 | hour, on the hour: |
1319 | |
1466 | |
1320 | ev_periodic_set (&periodic, 0., 3600., 0); |
1467 | ev_periodic_set (&periodic, 0., 3600., 0); |
1321 | |
1468 | |
1322 | This doesn't mean there will always be 3600 seconds in between triggers, |
1469 | This doesn't mean there will always be 3600 seconds in between triggers, |
1323 | but only that the the callback will be called when the system time shows a |
1470 | but only that the callback will be called when the system time shows a |
1324 | full hour (UTC), or more correctly, when the system time is evenly divisible |
1471 | full hour (UTC), or more correctly, when the system time is evenly divisible |
1325 | by 3600. |
1472 | by 3600. |
1326 | |
1473 | |
1327 | Another way to think about it (for the mathematically inclined) is that |
1474 | Another way to think about it (for the mathematically inclined) is that |
1328 | C<ev_periodic> will try to run the callback in this mode at the next possible |
1475 | C<ev_periodic> will try to run the callback in this mode at the next possible |
1329 | time where C<time = at (mod interval)>, regardless of any time jumps. |
1476 | time where C<time = at (mod interval)>, regardless of any time jumps. |
1330 | |
1477 | |
1331 | For numerical stability it is preferable that the C<at> value is near |
1478 | For numerical stability it is preferable that the C<at> value is near |
1332 | C<ev_now ()> (the current time), but there is no range requirement for |
1479 | C<ev_now ()> (the current time), but there is no range requirement for |
1333 | this value. |
1480 | this value, and in fact is often specified as zero. |
|
|
1481 | |
|
|
1482 | Note also that there is an upper limit to how often a timer can fire (CPU |
|
|
1483 | speed for example), so if C<interval> is very small then timing stability |
|
|
1484 | will of course deteriorate. Libev itself tries to be exact to be about one |
|
|
1485 | millisecond (if the OS supports it and the machine is fast enough). |
1334 | |
1486 | |
1335 | =item * manual reschedule mode (at and interval ignored, reschedule_cb = callback) |
1487 | =item * manual reschedule mode (at and interval ignored, reschedule_cb = callback) |
1336 | |
1488 | |
1337 | In this mode the values for C<interval> and C<at> are both being |
1489 | In this mode the values for C<interval> and C<at> are both being |
1338 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1490 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1339 | reschedule callback will be called with the watcher as first, and the |
1491 | reschedule callback will be called with the watcher as first, and the |
1340 | current time as second argument. |
1492 | current time as second argument. |
1341 | |
1493 | |
1342 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
1494 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
1343 | ever, or make any event loop modifications>. If you need to stop it, |
1495 | ever, or make ANY event loop modifications whatsoever>. |
1344 | return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by |
|
|
1345 | starting an C<ev_prepare> watcher, which is legal). |
|
|
1346 | |
1496 | |
|
|
1497 | If you need to stop it, return C<now + 1e30> (or so, fudge fudge) and stop |
|
|
1498 | it afterwards (e.g. by starting an C<ev_prepare> watcher, which is the |
|
|
1499 | only event loop modification you are allowed to do). |
|
|
1500 | |
1347 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1501 | The callback prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic |
1348 | ev_tstamp now)>, e.g.: |
1502 | *w, ev_tstamp now)>, e.g.: |
1349 | |
1503 | |
1350 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
1504 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
1351 | { |
1505 | { |
1352 | return now + 60.; |
1506 | return now + 60.; |
1353 | } |
1507 | } |
… | |
… | |
1355 | It must return the next time to trigger, based on the passed time value |
1509 | It must return the next time to trigger, based on the passed time value |
1356 | (that is, the lowest time value larger than to the second argument). It |
1510 | (that is, the lowest time value larger than to the second argument). It |
1357 | will usually be called just before the callback will be triggered, but |
1511 | will usually be called just before the callback will be triggered, but |
1358 | might be called at other times, too. |
1512 | might be called at other times, too. |
1359 | |
1513 | |
1360 | NOTE: I<< This callback must always return a time that is later than the |
1514 | NOTE: I<< This callback must always return a time that is higher than or |
1361 | passed C<now> value >>. Not even C<now> itself will do, it I<must> be larger. |
1515 | equal to the passed C<now> value >>. |
1362 | |
1516 | |
1363 | This can be used to create very complex timers, such as a timer that |
1517 | This can be used to create very complex timers, such as a timer that |
1364 | triggers on each midnight, local time. To do this, you would calculate the |
1518 | triggers on "next midnight, local time". To do this, you would calculate the |
1365 | next midnight after C<now> and return the timestamp value for this. How |
1519 | next midnight after C<now> and return the timestamp value for this. How |
1366 | you do this is, again, up to you (but it is not trivial, which is the main |
1520 | you do this is, again, up to you (but it is not trivial, which is the main |
1367 | reason I omitted it as an example). |
1521 | reason I omitted it as an example). |
1368 | |
1522 | |
1369 | =back |
1523 | =back |
… | |
… | |
1403 | =back |
1557 | =back |
1404 | |
1558 | |
1405 | =head3 Examples |
1559 | =head3 Examples |
1406 | |
1560 | |
1407 | Example: Call a callback every hour, or, more precisely, whenever the |
1561 | Example: Call a callback every hour, or, more precisely, whenever the |
1408 | system clock is divisible by 3600. The callback invocation times have |
1562 | system time is divisible by 3600. The callback invocation times have |
1409 | potentially a lot of jittering, but good long-term stability. |
1563 | potentially a lot of jitter, but good long-term stability. |
1410 | |
1564 | |
1411 | static void |
1565 | static void |
1412 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1566 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1413 | { |
1567 | { |
1414 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
1568 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
1415 | } |
1569 | } |
1416 | |
1570 | |
1417 | struct ev_periodic hourly_tick; |
1571 | struct ev_periodic hourly_tick; |
1418 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1572 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1419 | ev_periodic_start (loop, &hourly_tick); |
1573 | ev_periodic_start (loop, &hourly_tick); |
1420 | |
1574 | |
1421 | Example: The same as above, but use a reschedule callback to do it: |
1575 | Example: The same as above, but use a reschedule callback to do it: |
1422 | |
1576 | |
1423 | #include <math.h> |
1577 | #include <math.h> |
1424 | |
1578 | |
1425 | static ev_tstamp |
1579 | static ev_tstamp |
1426 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
1580 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
1427 | { |
1581 | { |
1428 | return fmod (now, 3600.) + 3600.; |
1582 | return now + (3600. - fmod (now, 3600.)); |
1429 | } |
1583 | } |
1430 | |
1584 | |
1431 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1585 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1432 | |
1586 | |
1433 | Example: Call a callback every hour, starting now: |
1587 | Example: Call a callback every hour, starting now: |
1434 | |
1588 | |
1435 | struct ev_periodic hourly_tick; |
1589 | struct ev_periodic hourly_tick; |
1436 | ev_periodic_init (&hourly_tick, clock_cb, |
1590 | ev_periodic_init (&hourly_tick, clock_cb, |
1437 | fmod (ev_now (loop), 3600.), 3600., 0); |
1591 | fmod (ev_now (loop), 3600.), 3600., 0); |
1438 | ev_periodic_start (loop, &hourly_tick); |
1592 | ev_periodic_start (loop, &hourly_tick); |
1439 | |
1593 | |
1440 | |
1594 | |
1441 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
1595 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
1442 | |
1596 | |
1443 | Signal watchers will trigger an event when the process receives a specific |
1597 | Signal watchers will trigger an event when the process receives a specific |
1444 | signal one or more times. Even though signals are very asynchronous, libev |
1598 | signal one or more times. Even though signals are very asynchronous, libev |
1445 | will try it's best to deliver signals synchronously, i.e. as part of the |
1599 | will try it's best to deliver signals synchronously, i.e. as part of the |
1446 | normal event processing, like any other event. |
1600 | normal event processing, like any other event. |
1447 | |
1601 | |
|
|
1602 | If you want signals asynchronously, just use C<sigaction> as you would |
|
|
1603 | do without libev and forget about sharing the signal. You can even use |
|
|
1604 | C<ev_async> from a signal handler to synchronously wake up an event loop. |
|
|
1605 | |
1448 | You can configure as many watchers as you like per signal. Only when the |
1606 | You can configure as many watchers as you like per signal. Only when the |
1449 | first watcher gets started will libev actually register a signal watcher |
1607 | first watcher gets started will libev actually register a signal handler |
1450 | with the kernel (thus it coexists with your own signal handlers as long |
1608 | with the kernel (thus it coexists with your own signal handlers as long as |
1451 | as you don't register any with libev). Similarly, when the last signal |
1609 | you don't register any with libev for the same signal). Similarly, when |
1452 | watcher for a signal is stopped libev will reset the signal handler to |
1610 | the last signal watcher for a signal is stopped, libev will reset the |
1453 | SIG_DFL (regardless of what it was set to before). |
1611 | signal handler to SIG_DFL (regardless of what it was set to before). |
1454 | |
1612 | |
1455 | If possible and supported, libev will install its handlers with |
1613 | If possible and supported, libev will install its handlers with |
1456 | C<SA_RESTART> behaviour enabled, so syscalls should not be unduly |
1614 | C<SA_RESTART> behaviour enabled, so system calls should not be unduly |
1457 | interrupted. If you have a problem with syscalls getting interrupted by |
1615 | interrupted. If you have a problem with system calls getting interrupted by |
1458 | signals you can block all signals in an C<ev_check> watcher and unblock |
1616 | signals you can block all signals in an C<ev_check> watcher and unblock |
1459 | them in an C<ev_prepare> watcher. |
1617 | them in an C<ev_prepare> watcher. |
1460 | |
1618 | |
1461 | =head3 Watcher-Specific Functions and Data Members |
1619 | =head3 Watcher-Specific Functions and Data Members |
1462 | |
1620 | |
… | |
… | |
1475 | |
1633 | |
1476 | =back |
1634 | =back |
1477 | |
1635 | |
1478 | =head3 Examples |
1636 | =head3 Examples |
1479 | |
1637 | |
1480 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
1638 | Example: Try to exit cleanly on SIGINT. |
1481 | |
1639 | |
1482 | static void |
1640 | static void |
1483 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1641 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1484 | { |
1642 | { |
1485 | ev_unloop (loop, EVUNLOOP_ALL); |
1643 | ev_unloop (loop, EVUNLOOP_ALL); |
1486 | } |
1644 | } |
1487 | |
1645 | |
1488 | struct ev_signal signal_watcher; |
1646 | struct ev_signal signal_watcher; |
1489 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1647 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1490 | ev_signal_start (loop, &sigint_cb); |
1648 | ev_signal_start (loop, &signal_watcher); |
1491 | |
1649 | |
1492 | |
1650 | |
1493 | =head2 C<ev_child> - watch out for process status changes |
1651 | =head2 C<ev_child> - watch out for process status changes |
1494 | |
1652 | |
1495 | Child watchers trigger when your process receives a SIGCHLD in response to |
1653 | Child watchers trigger when your process receives a SIGCHLD in response to |
1496 | some child status changes (most typically when a child of yours dies). It |
1654 | some child status changes (most typically when a child of yours dies or |
1497 | is permissible to install a child watcher I<after> the child has been |
1655 | exits). It is permissible to install a child watcher I<after> the child |
1498 | forked (which implies it might have already exited), as long as the event |
1656 | has been forked (which implies it might have already exited), as long |
1499 | loop isn't entered (or is continued from a watcher). |
1657 | as the event loop isn't entered (or is continued from a watcher), i.e., |
|
|
1658 | forking and then immediately registering a watcher for the child is fine, |
|
|
1659 | but forking and registering a watcher a few event loop iterations later is |
|
|
1660 | not. |
1500 | |
1661 | |
1501 | Only the default event loop is capable of handling signals, and therefore |
1662 | Only the default event loop is capable of handling signals, and therefore |
1502 | you can only rgeister child watchers in the default event loop. |
1663 | you can only register child watchers in the default event loop. |
1503 | |
1664 | |
1504 | =head3 Process Interaction |
1665 | =head3 Process Interaction |
1505 | |
1666 | |
1506 | Libev grabs C<SIGCHLD> as soon as the default event loop is |
1667 | Libev grabs C<SIGCHLD> as soon as the default event loop is |
1507 | initialised. This is necessary to guarantee proper behaviour even if |
1668 | initialised. This is necessary to guarantee proper behaviour even if |
1508 | the first child watcher is started after the child exits. The occurance |
1669 | the first child watcher is started after the child exits. The occurrence |
1509 | of C<SIGCHLD> is recorded asynchronously, but child reaping is done |
1670 | of C<SIGCHLD> is recorded asynchronously, but child reaping is done |
1510 | synchronously as part of the event loop processing. Libev always reaps all |
1671 | synchronously as part of the event loop processing. Libev always reaps all |
1511 | children, even ones not watched. |
1672 | children, even ones not watched. |
1512 | |
1673 | |
1513 | =head3 Overriding the Built-In Processing |
1674 | =head3 Overriding the Built-In Processing |
… | |
… | |
1517 | handler, you can override it easily by installing your own handler for |
1678 | handler, you can override it easily by installing your own handler for |
1518 | C<SIGCHLD> after initialising the default loop, and making sure the |
1679 | C<SIGCHLD> after initialising the default loop, and making sure the |
1519 | default loop never gets destroyed. You are encouraged, however, to use an |
1680 | default loop never gets destroyed. You are encouraged, however, to use an |
1520 | event-based approach to child reaping and thus use libev's support for |
1681 | event-based approach to child reaping and thus use libev's support for |
1521 | that, so other libev users can use C<ev_child> watchers freely. |
1682 | that, so other libev users can use C<ev_child> watchers freely. |
|
|
1683 | |
|
|
1684 | =head3 Stopping the Child Watcher |
|
|
1685 | |
|
|
1686 | Currently, the child watcher never gets stopped, even when the |
|
|
1687 | child terminates, so normally one needs to stop the watcher in the |
|
|
1688 | callback. Future versions of libev might stop the watcher automatically |
|
|
1689 | when a child exit is detected. |
1522 | |
1690 | |
1523 | =head3 Watcher-Specific Functions and Data Members |
1691 | =head3 Watcher-Specific Functions and Data Members |
1524 | |
1692 | |
1525 | =over 4 |
1693 | =over 4 |
1526 | |
1694 | |
… | |
… | |
1555 | =head3 Examples |
1723 | =head3 Examples |
1556 | |
1724 | |
1557 | Example: C<fork()> a new process and install a child handler to wait for |
1725 | Example: C<fork()> a new process and install a child handler to wait for |
1558 | its completion. |
1726 | its completion. |
1559 | |
1727 | |
1560 | ev_child cw; |
1728 | ev_child cw; |
1561 | |
1729 | |
1562 | static void |
1730 | static void |
1563 | child_cb (EV_P_ struct ev_child *w, int revents) |
1731 | child_cb (EV_P_ struct ev_child *w, int revents) |
1564 | { |
1732 | { |
1565 | ev_child_stop (EV_A_ w); |
1733 | ev_child_stop (EV_A_ w); |
1566 | printf ("process %d exited with status %x\n", w->rpid, w->rstatus); |
1734 | printf ("process %d exited with status %x\n", w->rpid, w->rstatus); |
1567 | } |
1735 | } |
1568 | |
1736 | |
1569 | pid_t pid = fork (); |
1737 | pid_t pid = fork (); |
1570 | |
1738 | |
1571 | if (pid < 0) |
1739 | if (pid < 0) |
1572 | // error |
1740 | // error |
1573 | else if (pid == 0) |
1741 | else if (pid == 0) |
1574 | { |
1742 | { |
1575 | // the forked child executes here |
1743 | // the forked child executes here |
1576 | exit (1); |
1744 | exit (1); |
1577 | } |
1745 | } |
1578 | else |
1746 | else |
1579 | { |
1747 | { |
1580 | ev_child_init (&cw, child_cb, pid, 0); |
1748 | ev_child_init (&cw, child_cb, pid, 0); |
1581 | ev_child_start (EV_DEFAULT_ &cw); |
1749 | ev_child_start (EV_DEFAULT_ &cw); |
1582 | } |
1750 | } |
1583 | |
1751 | |
1584 | |
1752 | |
1585 | =head2 C<ev_stat> - did the file attributes just change? |
1753 | =head2 C<ev_stat> - did the file attributes just change? |
1586 | |
1754 | |
1587 | This watches a filesystem path for attribute changes. That is, it calls |
1755 | This watches a file system path for attribute changes. That is, it calls |
1588 | C<stat> regularly (or when the OS says it changed) and sees if it changed |
1756 | C<stat> regularly (or when the OS says it changed) and sees if it changed |
1589 | compared to the last time, invoking the callback if it did. |
1757 | compared to the last time, invoking the callback if it did. |
1590 | |
1758 | |
1591 | The path does not need to exist: changing from "path exists" to "path does |
1759 | The path does not need to exist: changing from "path exists" to "path does |
1592 | not exist" is a status change like any other. The condition "path does |
1760 | not exist" is a status change like any other. The condition "path does |
… | |
… | |
1595 | the stat buffer having unspecified contents. |
1763 | the stat buffer having unspecified contents. |
1596 | |
1764 | |
1597 | The path I<should> be absolute and I<must not> end in a slash. If it is |
1765 | The path I<should> be absolute and I<must not> end in a slash. If it is |
1598 | relative and your working directory changes, the behaviour is undefined. |
1766 | relative and your working directory changes, the behaviour is undefined. |
1599 | |
1767 | |
1600 | Since there is no standard to do this, the portable implementation simply |
1768 | Since there is no standard kernel interface to do this, the portable |
1601 | calls C<stat (2)> regularly on the path to see if it changed somehow. You |
1769 | implementation simply calls C<stat (2)> regularly on the path to see if |
1602 | can specify a recommended polling interval for this case. If you specify |
1770 | it changed somehow. You can specify a recommended polling interval for |
1603 | a polling interval of C<0> (highly recommended!) then a I<suitable, |
1771 | this case. If you specify a polling interval of C<0> (highly recommended!) |
1604 | unspecified default> value will be used (which you can expect to be around |
1772 | then a I<suitable, unspecified default> value will be used (which |
1605 | five seconds, although this might change dynamically). Libev will also |
1773 | you can expect to be around five seconds, although this might change |
1606 | impose a minimum interval which is currently around C<0.1>, but thats |
1774 | dynamically). Libev will also impose a minimum interval which is currently |
1607 | usually overkill. |
1775 | around C<0.1>, but thats usually overkill. |
1608 | |
1776 | |
1609 | This watcher type is not meant for massive numbers of stat watchers, |
1777 | This watcher type is not meant for massive numbers of stat watchers, |
1610 | as even with OS-supported change notifications, this can be |
1778 | as even with OS-supported change notifications, this can be |
1611 | resource-intensive. |
1779 | resource-intensive. |
1612 | |
1780 | |
1613 | At the time of this writing, only the Linux inotify interface is |
1781 | At the time of this writing, the only OS-specific interface implemented |
1614 | implemented (implementing kqueue support is left as an exercise for the |
1782 | is the Linux inotify interface (implementing kqueue support is left as |
1615 | reader, note, however, that the author sees no way of implementing ev_stat |
1783 | an exercise for the reader. Note, however, that the author sees no way |
1616 | semantics with kqueue). Inotify will be used to give hints only and should |
1784 | of implementing C<ev_stat> semantics with kqueue). |
1617 | not change the semantics of C<ev_stat> watchers, which means that libev |
|
|
1618 | sometimes needs to fall back to regular polling again even with inotify, |
|
|
1619 | but changes are usually detected immediately, and if the file exists there |
|
|
1620 | will be no polling. |
|
|
1621 | |
1785 | |
1622 | =head3 ABI Issues (Largefile Support) |
1786 | =head3 ABI Issues (Largefile Support) |
1623 | |
1787 | |
1624 | Libev by default (unless the user overrides this) uses the default |
1788 | Libev by default (unless the user overrides this) uses the default |
1625 | compilation environment, which means that on systems with optionally |
1789 | compilation environment, which means that on systems with large file |
1626 | disabled large file support, you get the 32 bit version of the stat |
1790 | support disabled by default, you get the 32 bit version of the stat |
1627 | structure. When using the library from programs that change the ABI to |
1791 | structure. When using the library from programs that change the ABI to |
1628 | use 64 bit file offsets the programs will fail. In that case you have to |
1792 | use 64 bit file offsets the programs will fail. In that case you have to |
1629 | compile libev with the same flags to get binary compatibility. This is |
1793 | compile libev with the same flags to get binary compatibility. This is |
1630 | obviously the case with any flags that change the ABI, but the problem is |
1794 | obviously the case with any flags that change the ABI, but the problem is |
1631 | most noticably with ev_stat and largefile support. |
1795 | most noticeably disabled with ev_stat and large file support. |
1632 | |
1796 | |
1633 | =head3 Inotify |
1797 | The solution for this is to lobby your distribution maker to make large |
|
|
1798 | file interfaces available by default (as e.g. FreeBSD does) and not |
|
|
1799 | optional. Libev cannot simply switch on large file support because it has |
|
|
1800 | to exchange stat structures with application programs compiled using the |
|
|
1801 | default compilation environment. |
1634 | |
1802 | |
|
|
1803 | =head3 Inotify and Kqueue |
|
|
1804 | |
1635 | When C<inotify (7)> support has been compiled into libev (generally only |
1805 | When C<inotify (7)> support has been compiled into libev (generally |
|
|
1806 | only available with Linux 2.6.25 or above due to bugs in earlier |
1636 | available on Linux) and present at runtime, it will be used to speed up |
1807 | implementations) and present at runtime, it will be used to speed up |
1637 | change detection where possible. The inotify descriptor will be created lazily |
1808 | change detection where possible. The inotify descriptor will be created |
1638 | when the first C<ev_stat> watcher is being started. |
1809 | lazily when the first C<ev_stat> watcher is being started. |
1639 | |
1810 | |
1640 | Inotify presence does not change the semantics of C<ev_stat> watchers |
1811 | Inotify presence does not change the semantics of C<ev_stat> watchers |
1641 | except that changes might be detected earlier, and in some cases, to avoid |
1812 | except that changes might be detected earlier, and in some cases, to avoid |
1642 | making regular C<stat> calls. Even in the presence of inotify support |
1813 | making regular C<stat> calls. Even in the presence of inotify support |
1643 | there are many cases where libev has to resort to regular C<stat> polling. |
1814 | there are many cases where libev has to resort to regular C<stat> polling, |
|
|
1815 | but as long as the path exists, libev usually gets away without polling. |
1644 | |
1816 | |
1645 | (There is no support for kqueue, as apparently it cannot be used to |
1817 | There is no support for kqueue, as apparently it cannot be used to |
1646 | implement this functionality, due to the requirement of having a file |
1818 | implement this functionality, due to the requirement of having a file |
1647 | descriptor open on the object at all times). |
1819 | descriptor open on the object at all times, and detecting renames, unlinks |
|
|
1820 | etc. is difficult. |
1648 | |
1821 | |
1649 | =head3 The special problem of stat time resolution |
1822 | =head3 The special problem of stat time resolution |
1650 | |
1823 | |
1651 | The C<stat ()> syscall only supports full-second resolution portably, and |
1824 | The C<stat ()> system call only supports full-second resolution portably, and |
1652 | even on systems where the resolution is higher, many filesystems still |
1825 | even on systems where the resolution is higher, most file systems still |
1653 | only support whole seconds. |
1826 | only support whole seconds. |
1654 | |
1827 | |
1655 | That means that, if the time is the only thing that changes, you can |
1828 | That means that, if the time is the only thing that changes, you can |
1656 | easily miss updates: on the first update, C<ev_stat> detects a change and |
1829 | easily miss updates: on the first update, C<ev_stat> detects a change and |
1657 | calls your callback, which does something. When there is another update |
1830 | calls your callback, which does something. When there is another update |
1658 | within the same second, C<ev_stat> will be unable to detect it as the stat |
1831 | within the same second, C<ev_stat> will be unable to detect unless the |
1659 | data does not change. |
1832 | stat data does change in other ways (e.g. file size). |
1660 | |
1833 | |
1661 | The solution to this is to delay acting on a change for slightly more |
1834 | The solution to this is to delay acting on a change for slightly more |
1662 | than second (or till slightly after the next full second boundary), using |
1835 | than a second (or till slightly after the next full second boundary), using |
1663 | a roughly one-second-delay C<ev_timer> (e.g. C<ev_timer_set (w, 0., 1.02); |
1836 | a roughly one-second-delay C<ev_timer> (e.g. C<ev_timer_set (w, 0., 1.02); |
1664 | ev_timer_again (loop, w)>). |
1837 | ev_timer_again (loop, w)>). |
1665 | |
1838 | |
1666 | The C<.02> offset is added to work around small timing inconsistencies |
1839 | The C<.02> offset is added to work around small timing inconsistencies |
1667 | of some operating systems (where the second counter of the current time |
1840 | of some operating systems (where the second counter of the current time |
… | |
… | |
1684 | C<path>. The C<interval> is a hint on how quickly a change is expected to |
1857 | C<path>. The C<interval> is a hint on how quickly a change is expected to |
1685 | be detected and should normally be specified as C<0> to let libev choose |
1858 | be detected and should normally be specified as C<0> to let libev choose |
1686 | a suitable value. The memory pointed to by C<path> must point to the same |
1859 | a suitable value. The memory pointed to by C<path> must point to the same |
1687 | path for as long as the watcher is active. |
1860 | path for as long as the watcher is active. |
1688 | |
1861 | |
1689 | The callback will receive C<EV_STAT> when a change was detected, relative |
1862 | The callback will receive an C<EV_STAT> event when a change was detected, |
1690 | to the attributes at the time the watcher was started (or the last change |
1863 | relative to the attributes at the time the watcher was started (or the |
1691 | was detected). |
1864 | last change was detected). |
1692 | |
1865 | |
1693 | =item ev_stat_stat (loop, ev_stat *) |
1866 | =item ev_stat_stat (loop, ev_stat *) |
1694 | |
1867 | |
1695 | Updates the stat buffer immediately with new values. If you change the |
1868 | Updates the stat buffer immediately with new values. If you change the |
1696 | watched path in your callback, you could call this function to avoid |
1869 | watched path in your callback, you could call this function to avoid |
… | |
… | |
1717 | |
1890 | |
1718 | The specified interval. |
1891 | The specified interval. |
1719 | |
1892 | |
1720 | =item const char *path [read-only] |
1893 | =item const char *path [read-only] |
1721 | |
1894 | |
1722 | The filesystem path that is being watched. |
1895 | The file system path that is being watched. |
1723 | |
1896 | |
1724 | =back |
1897 | =back |
1725 | |
1898 | |
1726 | =head3 Examples |
1899 | =head3 Examples |
1727 | |
1900 | |
1728 | Example: Watch C</etc/passwd> for attribute changes. |
1901 | Example: Watch C</etc/passwd> for attribute changes. |
1729 | |
1902 | |
1730 | static void |
1903 | static void |
1731 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
1904 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
1732 | { |
1905 | { |
1733 | /* /etc/passwd changed in some way */ |
1906 | /* /etc/passwd changed in some way */ |
1734 | if (w->attr.st_nlink) |
1907 | if (w->attr.st_nlink) |
1735 | { |
1908 | { |
1736 | printf ("passwd current size %ld\n", (long)w->attr.st_size); |
1909 | printf ("passwd current size %ld\n", (long)w->attr.st_size); |
1737 | printf ("passwd current atime %ld\n", (long)w->attr.st_mtime); |
1910 | printf ("passwd current atime %ld\n", (long)w->attr.st_mtime); |
1738 | printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime); |
1911 | printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime); |
1739 | } |
1912 | } |
1740 | else |
1913 | else |
1741 | /* you shalt not abuse printf for puts */ |
1914 | /* you shalt not abuse printf for puts */ |
1742 | puts ("wow, /etc/passwd is not there, expect problems. " |
1915 | puts ("wow, /etc/passwd is not there, expect problems. " |
1743 | "if this is windows, they already arrived\n"); |
1916 | "if this is windows, they already arrived\n"); |
1744 | } |
1917 | } |
1745 | |
1918 | |
1746 | ... |
1919 | ... |
1747 | ev_stat passwd; |
1920 | ev_stat passwd; |
1748 | |
1921 | |
1749 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.); |
1922 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.); |
1750 | ev_stat_start (loop, &passwd); |
1923 | ev_stat_start (loop, &passwd); |
1751 | |
1924 | |
1752 | Example: Like above, but additionally use a one-second delay so we do not |
1925 | Example: Like above, but additionally use a one-second delay so we do not |
1753 | miss updates (however, frequent updates will delay processing, too, so |
1926 | miss updates (however, frequent updates will delay processing, too, so |
1754 | one might do the work both on C<ev_stat> callback invocation I<and> on |
1927 | one might do the work both on C<ev_stat> callback invocation I<and> on |
1755 | C<ev_timer> callback invocation). |
1928 | C<ev_timer> callback invocation). |
1756 | |
1929 | |
1757 | static ev_stat passwd; |
1930 | static ev_stat passwd; |
1758 | static ev_timer timer; |
1931 | static ev_timer timer; |
1759 | |
1932 | |
1760 | static void |
1933 | static void |
1761 | timer_cb (EV_P_ ev_timer *w, int revents) |
1934 | timer_cb (EV_P_ ev_timer *w, int revents) |
1762 | { |
1935 | { |
1763 | ev_timer_stop (EV_A_ w); |
1936 | ev_timer_stop (EV_A_ w); |
1764 | |
1937 | |
1765 | /* now it's one second after the most recent passwd change */ |
1938 | /* now it's one second after the most recent passwd change */ |
1766 | } |
1939 | } |
1767 | |
1940 | |
1768 | static void |
1941 | static void |
1769 | stat_cb (EV_P_ ev_stat *w, int revents) |
1942 | stat_cb (EV_P_ ev_stat *w, int revents) |
1770 | { |
1943 | { |
1771 | /* reset the one-second timer */ |
1944 | /* reset the one-second timer */ |
1772 | ev_timer_again (EV_A_ &timer); |
1945 | ev_timer_again (EV_A_ &timer); |
1773 | } |
1946 | } |
1774 | |
1947 | |
1775 | ... |
1948 | ... |
1776 | ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); |
1949 | ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); |
1777 | ev_stat_start (loop, &passwd); |
1950 | ev_stat_start (loop, &passwd); |
1778 | ev_timer_init (&timer, timer_cb, 0., 1.02); |
1951 | ev_timer_init (&timer, timer_cb, 0., 1.02); |
1779 | |
1952 | |
1780 | |
1953 | |
1781 | =head2 C<ev_idle> - when you've got nothing better to do... |
1954 | =head2 C<ev_idle> - when you've got nothing better to do... |
1782 | |
1955 | |
1783 | Idle watchers trigger events when no other events of the same or higher |
1956 | Idle watchers trigger events when no other events of the same or higher |
1784 | priority are pending (prepare, check and other idle watchers do not |
1957 | priority are pending (prepare, check and other idle watchers do not count |
1785 | count). |
1958 | as receiving "events"). |
1786 | |
1959 | |
1787 | That is, as long as your process is busy handling sockets or timeouts |
1960 | That is, as long as your process is busy handling sockets or timeouts |
1788 | (or even signals, imagine) of the same or higher priority it will not be |
1961 | (or even signals, imagine) of the same or higher priority it will not be |
1789 | triggered. But when your process is idle (or only lower-priority watchers |
1962 | triggered. But when your process is idle (or only lower-priority watchers |
1790 | are pending), the idle watchers are being called once per event loop |
1963 | are pending), the idle watchers are being called once per event loop |
… | |
… | |
1814 | =head3 Examples |
1987 | =head3 Examples |
1815 | |
1988 | |
1816 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1989 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1817 | callback, free it. Also, use no error checking, as usual. |
1990 | callback, free it. Also, use no error checking, as usual. |
1818 | |
1991 | |
1819 | static void |
1992 | static void |
1820 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1993 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1821 | { |
1994 | { |
1822 | free (w); |
1995 | free (w); |
1823 | // now do something you wanted to do when the program has |
1996 | // now do something you wanted to do when the program has |
1824 | // no longer anything immediate to do. |
1997 | // no longer anything immediate to do. |
1825 | } |
1998 | } |
1826 | |
1999 | |
1827 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
2000 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1828 | ev_idle_init (idle_watcher, idle_cb); |
2001 | ev_idle_init (idle_watcher, idle_cb); |
1829 | ev_idle_start (loop, idle_cb); |
2002 | ev_idle_start (loop, idle_cb); |
1830 | |
2003 | |
1831 | |
2004 | |
1832 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
2005 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
1833 | |
2006 | |
1834 | Prepare and check watchers are usually (but not always) used in tandem: |
2007 | Prepare and check watchers are usually (but not always) used in pairs: |
1835 | prepare watchers get invoked before the process blocks and check watchers |
2008 | prepare watchers get invoked before the process blocks and check watchers |
1836 | afterwards. |
2009 | afterwards. |
1837 | |
2010 | |
1838 | You I<must not> call C<ev_loop> or similar functions that enter |
2011 | You I<must not> call C<ev_loop> or similar functions that enter |
1839 | the current event loop from either C<ev_prepare> or C<ev_check> |
2012 | the current event loop from either C<ev_prepare> or C<ev_check> |
… | |
… | |
1842 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
2015 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
1843 | C<ev_check> so if you have one watcher of each kind they will always be |
2016 | C<ev_check> so if you have one watcher of each kind they will always be |
1844 | called in pairs bracketing the blocking call. |
2017 | called in pairs bracketing the blocking call. |
1845 | |
2018 | |
1846 | Their main purpose is to integrate other event mechanisms into libev and |
2019 | Their main purpose is to integrate other event mechanisms into libev and |
1847 | their use is somewhat advanced. This could be used, for example, to track |
2020 | their use is somewhat advanced. They could be used, for example, to track |
1848 | variable changes, implement your own watchers, integrate net-snmp or a |
2021 | variable changes, implement your own watchers, integrate net-snmp or a |
1849 | coroutine library and lots more. They are also occasionally useful if |
2022 | coroutine library and lots more. They are also occasionally useful if |
1850 | you cache some data and want to flush it before blocking (for example, |
2023 | you cache some data and want to flush it before blocking (for example, |
1851 | in X programs you might want to do an C<XFlush ()> in an C<ev_prepare> |
2024 | in X programs you might want to do an C<XFlush ()> in an C<ev_prepare> |
1852 | watcher). |
2025 | watcher). |
1853 | |
2026 | |
1854 | This is done by examining in each prepare call which file descriptors need |
2027 | This is done by examining in each prepare call which file descriptors |
1855 | to be watched by the other library, registering C<ev_io> watchers for |
2028 | need to be watched by the other library, registering C<ev_io> watchers |
1856 | them and starting an C<ev_timer> watcher for any timeouts (many libraries |
2029 | for them and starting an C<ev_timer> watcher for any timeouts (many |
1857 | provide just this functionality). Then, in the check watcher you check for |
2030 | libraries provide exactly this functionality). Then, in the check watcher, |
1858 | any events that occured (by checking the pending status of all watchers |
2031 | you check for any events that occurred (by checking the pending status |
1859 | and stopping them) and call back into the library. The I/O and timer |
2032 | of all watchers and stopping them) and call back into the library. The |
1860 | callbacks will never actually be called (but must be valid nevertheless, |
2033 | I/O and timer callbacks will never actually be called (but must be valid |
1861 | because you never know, you know?). |
2034 | nevertheless, because you never know, you know?). |
1862 | |
2035 | |
1863 | As another example, the Perl Coro module uses these hooks to integrate |
2036 | As another example, the Perl Coro module uses these hooks to integrate |
1864 | coroutines into libev programs, by yielding to other active coroutines |
2037 | coroutines into libev programs, by yielding to other active coroutines |
1865 | during each prepare and only letting the process block if no coroutines |
2038 | during each prepare and only letting the process block if no coroutines |
1866 | are ready to run (it's actually more complicated: it only runs coroutines |
2039 | are ready to run (it's actually more complicated: it only runs coroutines |
… | |
… | |
1869 | loop from blocking if lower-priority coroutines are active, thus mapping |
2042 | loop from blocking if lower-priority coroutines are active, thus mapping |
1870 | low-priority coroutines to idle/background tasks). |
2043 | low-priority coroutines to idle/background tasks). |
1871 | |
2044 | |
1872 | It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>) |
2045 | It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>) |
1873 | priority, to ensure that they are being run before any other watchers |
2046 | priority, to ensure that they are being run before any other watchers |
|
|
2047 | after the poll (this doesn't matter for C<ev_prepare> watchers). |
|
|
2048 | |
1874 | after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers, |
2049 | Also, C<ev_check> watchers (and C<ev_prepare> watchers, too) should not |
1875 | too) should not activate ("feed") events into libev. While libev fully |
2050 | activate ("feed") events into libev. While libev fully supports this, they |
1876 | supports this, they might get executed before other C<ev_check> watchers |
2051 | might get executed before other C<ev_check> watchers did their job. As |
1877 | did their job. As C<ev_check> watchers are often used to embed other |
2052 | C<ev_check> watchers are often used to embed other (non-libev) event |
1878 | (non-libev) event loops those other event loops might be in an unusable |
2053 | loops those other event loops might be in an unusable state until their |
1879 | state until their C<ev_check> watcher ran (always remind yourself to |
2054 | C<ev_check> watcher ran (always remind yourself to coexist peacefully with |
1880 | coexist peacefully with others). |
2055 | others). |
1881 | |
2056 | |
1882 | =head3 Watcher-Specific Functions and Data Members |
2057 | =head3 Watcher-Specific Functions and Data Members |
1883 | |
2058 | |
1884 | =over 4 |
2059 | =over 4 |
1885 | |
2060 | |
… | |
… | |
1887 | |
2062 | |
1888 | =item ev_check_init (ev_check *, callback) |
2063 | =item ev_check_init (ev_check *, callback) |
1889 | |
2064 | |
1890 | Initialises and configures the prepare or check watcher - they have no |
2065 | Initialises and configures the prepare or check watcher - they have no |
1891 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
2066 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1892 | macros, but using them is utterly, utterly and completely pointless. |
2067 | macros, but using them is utterly, utterly, utterly and completely |
|
|
2068 | pointless. |
1893 | |
2069 | |
1894 | =back |
2070 | =back |
1895 | |
2071 | |
1896 | =head3 Examples |
2072 | =head3 Examples |
1897 | |
2073 | |
… | |
… | |
1906 | and in a check watcher, destroy them and call into libadns. What follows |
2082 | and in a check watcher, destroy them and call into libadns. What follows |
1907 | is pseudo-code only of course. This requires you to either use a low |
2083 | is pseudo-code only of course. This requires you to either use a low |
1908 | priority for the check watcher or use C<ev_clear_pending> explicitly, as |
2084 | priority for the check watcher or use C<ev_clear_pending> explicitly, as |
1909 | the callbacks for the IO/timeout watchers might not have been called yet. |
2085 | the callbacks for the IO/timeout watchers might not have been called yet. |
1910 | |
2086 | |
1911 | static ev_io iow [nfd]; |
2087 | static ev_io iow [nfd]; |
1912 | static ev_timer tw; |
2088 | static ev_timer tw; |
1913 | |
2089 | |
1914 | static void |
2090 | static void |
1915 | io_cb (ev_loop *loop, ev_io *w, int revents) |
2091 | io_cb (ev_loop *loop, ev_io *w, int revents) |
1916 | { |
2092 | { |
1917 | } |
2093 | } |
1918 | |
2094 | |
1919 | // create io watchers for each fd and a timer before blocking |
2095 | // create io watchers for each fd and a timer before blocking |
1920 | static void |
2096 | static void |
1921 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
2097 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1922 | { |
2098 | { |
1923 | int timeout = 3600000; |
2099 | int timeout = 3600000; |
1924 | struct pollfd fds [nfd]; |
2100 | struct pollfd fds [nfd]; |
1925 | // actual code will need to loop here and realloc etc. |
2101 | // actual code will need to loop here and realloc etc. |
1926 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
2102 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1927 | |
2103 | |
1928 | /* the callback is illegal, but won't be called as we stop during check */ |
2104 | /* the callback is illegal, but won't be called as we stop during check */ |
1929 | ev_timer_init (&tw, 0, timeout * 1e-3); |
2105 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1930 | ev_timer_start (loop, &tw); |
2106 | ev_timer_start (loop, &tw); |
1931 | |
2107 | |
1932 | // create one ev_io per pollfd |
2108 | // create one ev_io per pollfd |
1933 | for (int i = 0; i < nfd; ++i) |
2109 | for (int i = 0; i < nfd; ++i) |
1934 | { |
2110 | { |
1935 | ev_io_init (iow + i, io_cb, fds [i].fd, |
2111 | ev_io_init (iow + i, io_cb, fds [i].fd, |
1936 | ((fds [i].events & POLLIN ? EV_READ : 0) |
2112 | ((fds [i].events & POLLIN ? EV_READ : 0) |
1937 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
2113 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1938 | |
2114 | |
1939 | fds [i].revents = 0; |
2115 | fds [i].revents = 0; |
1940 | ev_io_start (loop, iow + i); |
2116 | ev_io_start (loop, iow + i); |
1941 | } |
2117 | } |
1942 | } |
2118 | } |
1943 | |
2119 | |
1944 | // stop all watchers after blocking |
2120 | // stop all watchers after blocking |
1945 | static void |
2121 | static void |
1946 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
2122 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
1947 | { |
2123 | { |
1948 | ev_timer_stop (loop, &tw); |
2124 | ev_timer_stop (loop, &tw); |
1949 | |
2125 | |
1950 | for (int i = 0; i < nfd; ++i) |
2126 | for (int i = 0; i < nfd; ++i) |
1951 | { |
2127 | { |
1952 | // set the relevant poll flags |
2128 | // set the relevant poll flags |
1953 | // could also call adns_processreadable etc. here |
2129 | // could also call adns_processreadable etc. here |
1954 | struct pollfd *fd = fds + i; |
2130 | struct pollfd *fd = fds + i; |
1955 | int revents = ev_clear_pending (iow + i); |
2131 | int revents = ev_clear_pending (iow + i); |
1956 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
2132 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
1957 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
2133 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
1958 | |
2134 | |
1959 | // now stop the watcher |
2135 | // now stop the watcher |
1960 | ev_io_stop (loop, iow + i); |
2136 | ev_io_stop (loop, iow + i); |
1961 | } |
2137 | } |
1962 | |
2138 | |
1963 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
2139 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
1964 | } |
2140 | } |
1965 | |
2141 | |
1966 | Method 2: This would be just like method 1, but you run C<adns_afterpoll> |
2142 | Method 2: This would be just like method 1, but you run C<adns_afterpoll> |
1967 | in the prepare watcher and would dispose of the check watcher. |
2143 | in the prepare watcher and would dispose of the check watcher. |
1968 | |
2144 | |
1969 | Method 3: If the module to be embedded supports explicit event |
2145 | Method 3: If the module to be embedded supports explicit event |
1970 | notification (adns does), you can also make use of the actual watcher |
2146 | notification (libadns does), you can also make use of the actual watcher |
1971 | callbacks, and only destroy/create the watchers in the prepare watcher. |
2147 | callbacks, and only destroy/create the watchers in the prepare watcher. |
1972 | |
2148 | |
1973 | static void |
2149 | static void |
1974 | timer_cb (EV_P_ ev_timer *w, int revents) |
2150 | timer_cb (EV_P_ ev_timer *w, int revents) |
1975 | { |
2151 | { |
1976 | adns_state ads = (adns_state)w->data; |
2152 | adns_state ads = (adns_state)w->data; |
1977 | update_now (EV_A); |
2153 | update_now (EV_A); |
1978 | |
2154 | |
1979 | adns_processtimeouts (ads, &tv_now); |
2155 | adns_processtimeouts (ads, &tv_now); |
1980 | } |
2156 | } |
1981 | |
2157 | |
1982 | static void |
2158 | static void |
1983 | io_cb (EV_P_ ev_io *w, int revents) |
2159 | io_cb (EV_P_ ev_io *w, int revents) |
1984 | { |
2160 | { |
1985 | adns_state ads = (adns_state)w->data; |
2161 | adns_state ads = (adns_state)w->data; |
1986 | update_now (EV_A); |
2162 | update_now (EV_A); |
1987 | |
2163 | |
1988 | if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now); |
2164 | if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now); |
1989 | if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now); |
2165 | if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now); |
1990 | } |
2166 | } |
1991 | |
2167 | |
1992 | // do not ever call adns_afterpoll |
2168 | // do not ever call adns_afterpoll |
1993 | |
2169 | |
1994 | Method 4: Do not use a prepare or check watcher because the module you |
2170 | Method 4: Do not use a prepare or check watcher because the module you |
1995 | want to embed is too inflexible to support it. Instead, youc na override |
2171 | want to embed is not flexible enough to support it. Instead, you can |
1996 | their poll function. The drawback with this solution is that the main |
2172 | override their poll function. The drawback with this solution is that the |
1997 | loop is now no longer controllable by EV. The C<Glib::EV> module does |
2173 | main loop is now no longer controllable by EV. The C<Glib::EV> module uses |
1998 | this. |
2174 | this approach, effectively embedding EV as a client into the horrible |
|
|
2175 | libglib event loop. |
1999 | |
2176 | |
2000 | static gint |
2177 | static gint |
2001 | event_poll_func (GPollFD *fds, guint nfds, gint timeout) |
2178 | event_poll_func (GPollFD *fds, guint nfds, gint timeout) |
2002 | { |
2179 | { |
2003 | int got_events = 0; |
2180 | int got_events = 0; |
2004 | |
2181 | |
2005 | for (n = 0; n < nfds; ++n) |
2182 | for (n = 0; n < nfds; ++n) |
2006 | // create/start io watcher that sets the relevant bits in fds[n] and increment got_events |
2183 | // create/start io watcher that sets the relevant bits in fds[n] and increment got_events |
2007 | |
2184 | |
2008 | if (timeout >= 0) |
2185 | if (timeout >= 0) |
2009 | // create/start timer |
2186 | // create/start timer |
2010 | |
2187 | |
2011 | // poll |
2188 | // poll |
2012 | ev_loop (EV_A_ 0); |
2189 | ev_loop (EV_A_ 0); |
2013 | |
2190 | |
2014 | // stop timer again |
2191 | // stop timer again |
2015 | if (timeout >= 0) |
2192 | if (timeout >= 0) |
2016 | ev_timer_stop (EV_A_ &to); |
2193 | ev_timer_stop (EV_A_ &to); |
2017 | |
2194 | |
2018 | // stop io watchers again - their callbacks should have set |
2195 | // stop io watchers again - their callbacks should have set |
2019 | for (n = 0; n < nfds; ++n) |
2196 | for (n = 0; n < nfds; ++n) |
2020 | ev_io_stop (EV_A_ iow [n]); |
2197 | ev_io_stop (EV_A_ iow [n]); |
2021 | |
2198 | |
2022 | return got_events; |
2199 | return got_events; |
2023 | } |
2200 | } |
2024 | |
2201 | |
2025 | |
2202 | |
2026 | =head2 C<ev_embed> - when one backend isn't enough... |
2203 | =head2 C<ev_embed> - when one backend isn't enough... |
2027 | |
2204 | |
2028 | This is a rather advanced watcher type that lets you embed one event loop |
2205 | This is a rather advanced watcher type that lets you embed one event loop |
… | |
… | |
2034 | prioritise I/O. |
2211 | prioritise I/O. |
2035 | |
2212 | |
2036 | As an example for a bug workaround, the kqueue backend might only support |
2213 | As an example for a bug workaround, the kqueue backend might only support |
2037 | sockets on some platform, so it is unusable as generic backend, but you |
2214 | sockets on some platform, so it is unusable as generic backend, but you |
2038 | still want to make use of it because you have many sockets and it scales |
2215 | still want to make use of it because you have many sockets and it scales |
2039 | so nicely. In this case, you would create a kqueue-based loop and embed it |
2216 | so nicely. In this case, you would create a kqueue-based loop and embed |
2040 | into your default loop (which might use e.g. poll). Overall operation will |
2217 | it into your default loop (which might use e.g. poll). Overall operation |
2041 | be a bit slower because first libev has to poll and then call kevent, but |
2218 | will be a bit slower because first libev has to call C<poll> and then |
2042 | at least you can use both at what they are best. |
2219 | C<kevent>, but at least you can use both mechanisms for what they are |
|
|
2220 | best: C<kqueue> for scalable sockets and C<poll> if you want it to work :) |
2043 | |
2221 | |
2044 | As for prioritising I/O: rarely you have the case where some fds have |
2222 | As for prioritising I/O: under rare circumstances you have the case where |
2045 | to be watched and handled very quickly (with low latency), and even |
2223 | some fds have to be watched and handled very quickly (with low latency), |
2046 | priorities and idle watchers might have too much overhead. In this case |
2224 | and even priorities and idle watchers might have too much overhead. In |
2047 | you would put all the high priority stuff in one loop and all the rest in |
2225 | this case you would put all the high priority stuff in one loop and all |
2048 | a second one, and embed the second one in the first. |
2226 | the rest in a second one, and embed the second one in the first. |
2049 | |
2227 | |
2050 | As long as the watcher is active, the callback will be invoked every time |
2228 | As long as the watcher is active, the callback will be invoked every time |
2051 | there might be events pending in the embedded loop. The callback must then |
2229 | there might be events pending in the embedded loop. The callback must then |
2052 | call C<ev_embed_sweep (mainloop, watcher)> to make a single sweep and invoke |
2230 | call C<ev_embed_sweep (mainloop, watcher)> to make a single sweep and invoke |
2053 | their callbacks (you could also start an idle watcher to give the embedded |
2231 | their callbacks (you could also start an idle watcher to give the embedded |
… | |
… | |
2061 | interested in that. |
2239 | interested in that. |
2062 | |
2240 | |
2063 | Also, there have not currently been made special provisions for forking: |
2241 | Also, there have not currently been made special provisions for forking: |
2064 | when you fork, you not only have to call C<ev_loop_fork> on both loops, |
2242 | when you fork, you not only have to call C<ev_loop_fork> on both loops, |
2065 | but you will also have to stop and restart any C<ev_embed> watchers |
2243 | but you will also have to stop and restart any C<ev_embed> watchers |
2066 | yourself. |
2244 | yourself - but you can use a fork watcher to handle this automatically, |
|
|
2245 | and future versions of libev might do just that. |
2067 | |
2246 | |
2068 | Unfortunately, not all backends are embeddable, only the ones returned by |
2247 | Unfortunately, not all backends are embeddable: only the ones returned by |
2069 | C<ev_embeddable_backends> are, which, unfortunately, does not include any |
2248 | C<ev_embeddable_backends> are, which, unfortunately, does not include any |
2070 | portable one. |
2249 | portable one. |
2071 | |
2250 | |
2072 | So when you want to use this feature you will always have to be prepared |
2251 | So when you want to use this feature you will always have to be prepared |
2073 | that you cannot get an embeddable loop. The recommended way to get around |
2252 | that you cannot get an embeddable loop. The recommended way to get around |
2074 | this is to have a separate variables for your embeddable loop, try to |
2253 | this is to have a separate variables for your embeddable loop, try to |
2075 | create it, and if that fails, use the normal loop for everything. |
2254 | create it, and if that fails, use the normal loop for everything. |
2076 | |
2255 | |
|
|
2256 | =head3 C<ev_embed> and fork |
|
|
2257 | |
|
|
2258 | While the C<ev_embed> watcher is running, forks in the embedding loop will |
|
|
2259 | automatically be applied to the embedded loop as well, so no special |
|
|
2260 | fork handling is required in that case. When the watcher is not running, |
|
|
2261 | however, it is still the task of the libev user to call C<ev_loop_fork ()> |
|
|
2262 | as applicable. |
|
|
2263 | |
2077 | =head3 Watcher-Specific Functions and Data Members |
2264 | =head3 Watcher-Specific Functions and Data Members |
2078 | |
2265 | |
2079 | =over 4 |
2266 | =over 4 |
2080 | |
2267 | |
2081 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
2268 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
… | |
… | |
2084 | |
2271 | |
2085 | Configures the watcher to embed the given loop, which must be |
2272 | Configures the watcher to embed the given loop, which must be |
2086 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
2273 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
2087 | invoked automatically, otherwise it is the responsibility of the callback |
2274 | invoked automatically, otherwise it is the responsibility of the callback |
2088 | to invoke it (it will continue to be called until the sweep has been done, |
2275 | to invoke it (it will continue to be called until the sweep has been done, |
2089 | if you do not want thta, you need to temporarily stop the embed watcher). |
2276 | if you do not want that, you need to temporarily stop the embed watcher). |
2090 | |
2277 | |
2091 | =item ev_embed_sweep (loop, ev_embed *) |
2278 | =item ev_embed_sweep (loop, ev_embed *) |
2092 | |
2279 | |
2093 | Make a single, non-blocking sweep over the embedded loop. This works |
2280 | Make a single, non-blocking sweep over the embedded loop. This works |
2094 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
2281 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
2095 | apropriate way for embedded loops. |
2282 | appropriate way for embedded loops. |
2096 | |
2283 | |
2097 | =item struct ev_loop *other [read-only] |
2284 | =item struct ev_loop *other [read-only] |
2098 | |
2285 | |
2099 | The embedded event loop. |
2286 | The embedded event loop. |
2100 | |
2287 | |
… | |
… | |
2102 | |
2289 | |
2103 | =head3 Examples |
2290 | =head3 Examples |
2104 | |
2291 | |
2105 | Example: Try to get an embeddable event loop and embed it into the default |
2292 | Example: Try to get an embeddable event loop and embed it into the default |
2106 | event loop. If that is not possible, use the default loop. The default |
2293 | event loop. If that is not possible, use the default loop. The default |
2107 | loop is stored in C<loop_hi>, while the mebeddable loop is stored in |
2294 | loop is stored in C<loop_hi>, while the embeddable loop is stored in |
2108 | C<loop_lo> (which is C<loop_hi> in the acse no embeddable loop can be |
2295 | C<loop_lo> (which is C<loop_hi> in the case no embeddable loop can be |
2109 | used). |
2296 | used). |
2110 | |
2297 | |
2111 | struct ev_loop *loop_hi = ev_default_init (0); |
2298 | struct ev_loop *loop_hi = ev_default_init (0); |
2112 | struct ev_loop *loop_lo = 0; |
2299 | struct ev_loop *loop_lo = 0; |
2113 | struct ev_embed embed; |
2300 | struct ev_embed embed; |
2114 | |
2301 | |
2115 | // see if there is a chance of getting one that works |
2302 | // see if there is a chance of getting one that works |
2116 | // (remember that a flags value of 0 means autodetection) |
2303 | // (remember that a flags value of 0 means autodetection) |
2117 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
2304 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
2118 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
2305 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
2119 | : 0; |
2306 | : 0; |
2120 | |
2307 | |
2121 | // if we got one, then embed it, otherwise default to loop_hi |
2308 | // if we got one, then embed it, otherwise default to loop_hi |
2122 | if (loop_lo) |
2309 | if (loop_lo) |
2123 | { |
2310 | { |
2124 | ev_embed_init (&embed, 0, loop_lo); |
2311 | ev_embed_init (&embed, 0, loop_lo); |
2125 | ev_embed_start (loop_hi, &embed); |
2312 | ev_embed_start (loop_hi, &embed); |
2126 | } |
2313 | } |
2127 | else |
2314 | else |
2128 | loop_lo = loop_hi; |
2315 | loop_lo = loop_hi; |
2129 | |
2316 | |
2130 | Example: Check if kqueue is available but not recommended and create |
2317 | Example: Check if kqueue is available but not recommended and create |
2131 | a kqueue backend for use with sockets (which usually work with any |
2318 | a kqueue backend for use with sockets (which usually work with any |
2132 | kqueue implementation). Store the kqueue/socket-only event loop in |
2319 | kqueue implementation). Store the kqueue/socket-only event loop in |
2133 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
2320 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
2134 | |
2321 | |
2135 | struct ev_loop *loop = ev_default_init (0); |
2322 | struct ev_loop *loop = ev_default_init (0); |
2136 | struct ev_loop *loop_socket = 0; |
2323 | struct ev_loop *loop_socket = 0; |
2137 | struct ev_embed embed; |
2324 | struct ev_embed embed; |
2138 | |
2325 | |
2139 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
2326 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
2140 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
2327 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
2141 | { |
2328 | { |
2142 | ev_embed_init (&embed, 0, loop_socket); |
2329 | ev_embed_init (&embed, 0, loop_socket); |
2143 | ev_embed_start (loop, &embed); |
2330 | ev_embed_start (loop, &embed); |
2144 | } |
2331 | } |
2145 | |
2332 | |
2146 | if (!loop_socket) |
2333 | if (!loop_socket) |
2147 | loop_socket = loop; |
2334 | loop_socket = loop; |
2148 | |
2335 | |
2149 | // now use loop_socket for all sockets, and loop for everything else |
2336 | // now use loop_socket for all sockets, and loop for everything else |
2150 | |
2337 | |
2151 | |
2338 | |
2152 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
2339 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
2153 | |
2340 | |
2154 | Fork watchers are called when a C<fork ()> was detected (usually because |
2341 | Fork watchers are called when a C<fork ()> was detected (usually because |
… | |
… | |
2198 | is that the author does not know of a simple (or any) algorithm for a |
2385 | is that the author does not know of a simple (or any) algorithm for a |
2199 | multiple-writer-single-reader queue that works in all cases and doesn't |
2386 | multiple-writer-single-reader queue that works in all cases and doesn't |
2200 | need elaborate support such as pthreads. |
2387 | need elaborate support such as pthreads. |
2201 | |
2388 | |
2202 | That means that if you want to queue data, you have to provide your own |
2389 | That means that if you want to queue data, you have to provide your own |
2203 | queue. But at least I can tell you would implement locking around your |
2390 | queue. But at least I can tell you how to implement locking around your |
2204 | queue: |
2391 | queue: |
2205 | |
2392 | |
2206 | =over 4 |
2393 | =over 4 |
2207 | |
2394 | |
2208 | =item queueing from a signal handler context |
2395 | =item queueing from a signal handler context |
2209 | |
2396 | |
2210 | To implement race-free queueing, you simply add to the queue in the signal |
2397 | To implement race-free queueing, you simply add to the queue in the signal |
2211 | handler but you block the signal handler in the watcher callback. Here is an example that does that for |
2398 | handler but you block the signal handler in the watcher callback. Here is |
2212 | some fictitiuous SIGUSR1 handler: |
2399 | an example that does that for some fictitious SIGUSR1 handler: |
2213 | |
2400 | |
2214 | static ev_async mysig; |
2401 | static ev_async mysig; |
2215 | |
2402 | |
2216 | static void |
2403 | static void |
2217 | sigusr1_handler (void) |
2404 | sigusr1_handler (void) |
… | |
… | |
2284 | |
2471 | |
2285 | =item ev_async_init (ev_async *, callback) |
2472 | =item ev_async_init (ev_async *, callback) |
2286 | |
2473 | |
2287 | Initialises and configures the async watcher - it has no parameters of any |
2474 | Initialises and configures the async watcher - it has no parameters of any |
2288 | kind. There is a C<ev_asynd_set> macro, but using it is utterly pointless, |
2475 | kind. There is a C<ev_asynd_set> macro, but using it is utterly pointless, |
2289 | believe me. |
2476 | trust me. |
2290 | |
2477 | |
2291 | =item ev_async_send (loop, ev_async *) |
2478 | =item ev_async_send (loop, ev_async *) |
2292 | |
2479 | |
2293 | Sends/signals/activates the given C<ev_async> watcher, that is, feeds |
2480 | Sends/signals/activates the given C<ev_async> watcher, that is, feeds |
2294 | an C<EV_ASYNC> event on the watcher into the event loop. Unlike |
2481 | an C<EV_ASYNC> event on the watcher into the event loop. Unlike |
2295 | C<ev_feed_event>, this call is safe to do in other threads, signal or |
2482 | C<ev_feed_event>, this call is safe to do from other threads, signal or |
2296 | similar contexts (see the dicusssion of C<EV_ATOMIC_T> in the embedding |
2483 | similar contexts (see the discussion of C<EV_ATOMIC_T> in the embedding |
2297 | section below on what exactly this means). |
2484 | section below on what exactly this means). |
2298 | |
2485 | |
2299 | This call incurs the overhead of a syscall only once per loop iteration, |
2486 | This call incurs the overhead of a system call only once per loop iteration, |
2300 | so while the overhead might be noticable, it doesn't apply to repeated |
2487 | so while the overhead might be noticeable, it doesn't apply to repeated |
2301 | calls to C<ev_async_send>. |
2488 | calls to C<ev_async_send>. |
2302 | |
2489 | |
2303 | =item bool = ev_async_pending (ev_async *) |
2490 | =item bool = ev_async_pending (ev_async *) |
2304 | |
2491 | |
2305 | Returns a non-zero value when C<ev_async_send> has been called on the |
2492 | Returns a non-zero value when C<ev_async_send> has been called on the |
… | |
… | |
2307 | event loop. |
2494 | event loop. |
2308 | |
2495 | |
2309 | C<ev_async_send> sets a flag in the watcher and wakes up the loop. When |
2496 | C<ev_async_send> sets a flag in the watcher and wakes up the loop. When |
2310 | the loop iterates next and checks for the watcher to have become active, |
2497 | the loop iterates next and checks for the watcher to have become active, |
2311 | it will reset the flag again. C<ev_async_pending> can be used to very |
2498 | it will reset the flag again. C<ev_async_pending> can be used to very |
2312 | quickly check wether invoking the loop might be a good idea. |
2499 | quickly check whether invoking the loop might be a good idea. |
2313 | |
2500 | |
2314 | Not that this does I<not> check wether the watcher itself is pending, only |
2501 | Not that this does I<not> check whether the watcher itself is pending, only |
2315 | wether it has been requested to make this watcher pending. |
2502 | whether it has been requested to make this watcher pending. |
2316 | |
2503 | |
2317 | =back |
2504 | =back |
2318 | |
2505 | |
2319 | |
2506 | |
2320 | =head1 OTHER FUNCTIONS |
2507 | =head1 OTHER FUNCTIONS |
… | |
… | |
2324 | =over 4 |
2511 | =over 4 |
2325 | |
2512 | |
2326 | =item ev_once (loop, int fd, int events, ev_tstamp timeout, callback) |
2513 | =item ev_once (loop, int fd, int events, ev_tstamp timeout, callback) |
2327 | |
2514 | |
2328 | This function combines a simple timer and an I/O watcher, calls your |
2515 | This function combines a simple timer and an I/O watcher, calls your |
2329 | callback on whichever event happens first and automatically stop both |
2516 | callback on whichever event happens first and automatically stops both |
2330 | watchers. This is useful if you want to wait for a single event on an fd |
2517 | watchers. This is useful if you want to wait for a single event on an fd |
2331 | or timeout without having to allocate/configure/start/stop/free one or |
2518 | or timeout without having to allocate/configure/start/stop/free one or |
2332 | more watchers yourself. |
2519 | more watchers yourself. |
2333 | |
2520 | |
2334 | If C<fd> is less than 0, then no I/O watcher will be started and events |
2521 | If C<fd> is less than 0, then no I/O watcher will be started and the |
2335 | is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and |
2522 | C<events> argument is being ignored. Otherwise, an C<ev_io> watcher for |
2336 | C<events> set will be craeted and started. |
2523 | the given C<fd> and C<events> set will be created and started. |
2337 | |
2524 | |
2338 | If C<timeout> is less than 0, then no timeout watcher will be |
2525 | If C<timeout> is less than 0, then no timeout watcher will be |
2339 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
2526 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
2340 | repeat = 0) will be started. While C<0> is a valid timeout, it is of |
2527 | repeat = 0) will be started. C<0> is a valid timeout. |
2341 | dubious value. |
|
|
2342 | |
2528 | |
2343 | The callback has the type C<void (*cb)(int revents, void *arg)> and gets |
2529 | The callback has the type C<void (*cb)(int revents, void *arg)> and gets |
2344 | passed an C<revents> set like normal event callbacks (a combination of |
2530 | passed an C<revents> set like normal event callbacks (a combination of |
2345 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg> |
2531 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg> |
2346 | value passed to C<ev_once>: |
2532 | value passed to C<ev_once>. Note that it is possible to receive I<both> |
|
|
2533 | a timeout and an io event at the same time - you probably should give io |
|
|
2534 | events precedence. |
2347 | |
2535 | |
|
|
2536 | Example: wait up to ten seconds for data to appear on STDIN_FILENO. |
|
|
2537 | |
2348 | static void stdin_ready (int revents, void *arg) |
2538 | static void stdin_ready (int revents, void *arg) |
2349 | { |
2539 | { |
2350 | if (revents & EV_TIMEOUT) |
|
|
2351 | /* doh, nothing entered */; |
|
|
2352 | else if (revents & EV_READ) |
2540 | if (revents & EV_READ) |
2353 | /* stdin might have data for us, joy! */; |
2541 | /* stdin might have data for us, joy! */; |
|
|
2542 | else if (revents & EV_TIMEOUT) |
|
|
2543 | /* doh, nothing entered */; |
2354 | } |
2544 | } |
2355 | |
2545 | |
2356 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
2546 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
2357 | |
2547 | |
2358 | =item ev_feed_event (ev_loop *, watcher *, int revents) |
2548 | =item ev_feed_event (ev_loop *, watcher *, int revents) |
2359 | |
2549 | |
2360 | Feeds the given event set into the event loop, as if the specified event |
2550 | Feeds the given event set into the event loop, as if the specified event |
2361 | had happened for the specified watcher (which must be a pointer to an |
2551 | had happened for the specified watcher (which must be a pointer to an |
… | |
… | |
2366 | Feed an event on the given fd, as if a file descriptor backend detected |
2556 | Feed an event on the given fd, as if a file descriptor backend detected |
2367 | the given events it. |
2557 | the given events it. |
2368 | |
2558 | |
2369 | =item ev_feed_signal_event (ev_loop *loop, int signum) |
2559 | =item ev_feed_signal_event (ev_loop *loop, int signum) |
2370 | |
2560 | |
2371 | Feed an event as if the given signal occured (C<loop> must be the default |
2561 | Feed an event as if the given signal occurred (C<loop> must be the default |
2372 | loop!). |
2562 | loop!). |
2373 | |
2563 | |
2374 | =back |
2564 | =back |
2375 | |
2565 | |
2376 | |
2566 | |
… | |
… | |
2405 | =back |
2595 | =back |
2406 | |
2596 | |
2407 | =head1 C++ SUPPORT |
2597 | =head1 C++ SUPPORT |
2408 | |
2598 | |
2409 | Libev comes with some simplistic wrapper classes for C++ that mainly allow |
2599 | Libev comes with some simplistic wrapper classes for C++ that mainly allow |
2410 | you to use some convinience methods to start/stop watchers and also change |
2600 | you to use some convenience methods to start/stop watchers and also change |
2411 | the callback model to a model using method callbacks on objects. |
2601 | the callback model to a model using method callbacks on objects. |
2412 | |
2602 | |
2413 | To use it, |
2603 | To use it, |
2414 | |
2604 | |
2415 | #include <ev++.h> |
2605 | #include <ev++.h> |
2416 | |
2606 | |
2417 | This automatically includes F<ev.h> and puts all of its definitions (many |
2607 | This automatically includes F<ev.h> and puts all of its definitions (many |
2418 | of them macros) into the global namespace. All C++ specific things are |
2608 | of them macros) into the global namespace. All C++ specific things are |
2419 | put into the C<ev> namespace. It should support all the same embedding |
2609 | put into the C<ev> namespace. It should support all the same embedding |
2420 | options as F<ev.h>, most notably C<EV_MULTIPLICITY>. |
2610 | options as F<ev.h>, most notably C<EV_MULTIPLICITY>. |
… | |
… | |
2487 | your compiler is good :), then the method will be fully inlined into the |
2677 | your compiler is good :), then the method will be fully inlined into the |
2488 | thunking function, making it as fast as a direct C callback. |
2678 | thunking function, making it as fast as a direct C callback. |
2489 | |
2679 | |
2490 | Example: simple class declaration and watcher initialisation |
2680 | Example: simple class declaration and watcher initialisation |
2491 | |
2681 | |
2492 | struct myclass |
2682 | struct myclass |
2493 | { |
2683 | { |
2494 | void io_cb (ev::io &w, int revents) { } |
2684 | void io_cb (ev::io &w, int revents) { } |
2495 | } |
2685 | } |
2496 | |
2686 | |
2497 | myclass obj; |
2687 | myclass obj; |
2498 | ev::io iow; |
2688 | ev::io iow; |
2499 | iow.set <myclass, &myclass::io_cb> (&obj); |
2689 | iow.set <myclass, &myclass::io_cb> (&obj); |
2500 | |
2690 | |
2501 | =item w->set<function> (void *data = 0) |
2691 | =item w->set<function> (void *data = 0) |
2502 | |
2692 | |
2503 | Also sets a callback, but uses a static method or plain function as |
2693 | Also sets a callback, but uses a static method or plain function as |
2504 | callback. The optional C<data> argument will be stored in the watcher's |
2694 | callback. The optional C<data> argument will be stored in the watcher's |
… | |
… | |
2506 | |
2696 | |
2507 | The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>. |
2697 | The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>. |
2508 | |
2698 | |
2509 | See the method-C<set> above for more details. |
2699 | See the method-C<set> above for more details. |
2510 | |
2700 | |
2511 | Example: |
2701 | Example: Use a plain function as callback. |
2512 | |
2702 | |
2513 | static void io_cb (ev::io &w, int revents) { } |
2703 | static void io_cb (ev::io &w, int revents) { } |
2514 | iow.set <io_cb> (); |
2704 | iow.set <io_cb> (); |
2515 | |
2705 | |
2516 | =item w->set (struct ev_loop *) |
2706 | =item w->set (struct ev_loop *) |
2517 | |
2707 | |
2518 | Associates a different C<struct ev_loop> with this watcher. You can only |
2708 | Associates a different C<struct ev_loop> with this watcher. You can only |
2519 | do this when the watcher is inactive (and not pending either). |
2709 | do this when the watcher is inactive (and not pending either). |
2520 | |
2710 | |
2521 | =item w->set ([args]) |
2711 | =item w->set ([arguments]) |
2522 | |
2712 | |
2523 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
2713 | Basically the same as C<ev_TYPE_set>, with the same arguments. Must be |
2524 | called at least once. Unlike the C counterpart, an active watcher gets |
2714 | called at least once. Unlike the C counterpart, an active watcher gets |
2525 | automatically stopped and restarted when reconfiguring it with this |
2715 | automatically stopped and restarted when reconfiguring it with this |
2526 | method. |
2716 | method. |
2527 | |
2717 | |
2528 | =item w->start () |
2718 | =item w->start () |
… | |
… | |
2552 | =back |
2742 | =back |
2553 | |
2743 | |
2554 | Example: Define a class with an IO and idle watcher, start one of them in |
2744 | Example: Define a class with an IO and idle watcher, start one of them in |
2555 | the constructor. |
2745 | the constructor. |
2556 | |
2746 | |
2557 | class myclass |
2747 | class myclass |
2558 | { |
2748 | { |
2559 | ev::io io; void io_cb (ev::io &w, int revents); |
2749 | ev::io io ; void io_cb (ev::io &w, int revents); |
2560 | ev:idle idle void idle_cb (ev::idle &w, int revents); |
2750 | ev::idle idle; void idle_cb (ev::idle &w, int revents); |
2561 | |
2751 | |
2562 | myclass (int fd) |
2752 | myclass (int fd) |
2563 | { |
2753 | { |
2564 | io .set <myclass, &myclass::io_cb > (this); |
2754 | io .set <myclass, &myclass::io_cb > (this); |
2565 | idle.set <myclass, &myclass::idle_cb> (this); |
2755 | idle.set <myclass, &myclass::idle_cb> (this); |
2566 | |
2756 | |
2567 | io.start (fd, ev::READ); |
2757 | io.start (fd, ev::READ); |
2568 | } |
2758 | } |
2569 | }; |
2759 | }; |
2570 | |
2760 | |
2571 | |
2761 | |
2572 | =head1 OTHER LANGUAGE BINDINGS |
2762 | =head1 OTHER LANGUAGE BINDINGS |
2573 | |
2763 | |
2574 | Libev does not offer other language bindings itself, but bindings for a |
2764 | Libev does not offer other language bindings itself, but bindings for a |
2575 | numbe rof languages exist in the form of third-party packages. If you know |
2765 | number of languages exist in the form of third-party packages. If you know |
2576 | any interesting language binding in addition to the ones listed here, drop |
2766 | any interesting language binding in addition to the ones listed here, drop |
2577 | me a note. |
2767 | me a note. |
2578 | |
2768 | |
2579 | =over 4 |
2769 | =over 4 |
2580 | |
2770 | |
2581 | =item Perl |
2771 | =item Perl |
2582 | |
2772 | |
2583 | The EV module implements the full libev API and is actually used to test |
2773 | The EV module implements the full libev API and is actually used to test |
2584 | libev. EV is developed together with libev. Apart from the EV core module, |
2774 | libev. EV is developed together with libev. Apart from the EV core module, |
2585 | there are additional modules that implement libev-compatible interfaces |
2775 | there are additional modules that implement libev-compatible interfaces |
2586 | to C<libadns> (C<EV::ADNS>), C<Net::SNMP> (C<Net::SNMP::EV>) and the |
2776 | to C<libadns> (C<EV::ADNS>, but C<AnyEvent::DNS> is preferred nowadays), |
2587 | C<libglib> event core (C<Glib::EV> and C<EV::Glib>). |
2777 | C<Net::SNMP> (C<Net::SNMP::EV>) and the C<libglib> event core (C<Glib::EV> |
|
|
2778 | and C<EV::Glib>). |
2588 | |
2779 | |
2589 | It can be found and installed via CPAN, its homepage is found at |
2780 | It can be found and installed via CPAN, its homepage is at |
2590 | L<http://software.schmorp.de/pkg/EV>. |
2781 | L<http://software.schmorp.de/pkg/EV>. |
2591 | |
2782 | |
|
|
2783 | =item Python |
|
|
2784 | |
|
|
2785 | Python bindings can be found at L<http://code.google.com/p/pyev/>. It |
|
|
2786 | seems to be quite complete and well-documented. Note, however, that the |
|
|
2787 | patch they require for libev is outright dangerous as it breaks the ABI |
|
|
2788 | for everybody else, and therefore, should never be applied in an installed |
|
|
2789 | libev (if python requires an incompatible ABI then it needs to embed |
|
|
2790 | libev). |
|
|
2791 | |
2592 | =item Ruby |
2792 | =item Ruby |
2593 | |
2793 | |
2594 | Tony Arcieri has written a ruby extension that offers access to a subset |
2794 | Tony Arcieri has written a ruby extension that offers access to a subset |
2595 | of the libev API and adds filehandle abstractions, asynchronous DNS and |
2795 | of the libev API and adds file handle abstractions, asynchronous DNS and |
2596 | more on top of it. It can be found via gem servers. Its homepage is at |
2796 | more on top of it. It can be found via gem servers. Its homepage is at |
2597 | L<http://rev.rubyforge.org/>. |
2797 | L<http://rev.rubyforge.org/>. |
2598 | |
2798 | |
2599 | =item D |
2799 | =item D |
2600 | |
2800 | |
2601 | Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to |
2801 | Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to |
2602 | be found at L<http://git.llucax.com.ar/?p=software/ev.d.git;a=summary>. |
2802 | be found at L<http://proj.llucax.com.ar/wiki/evd>. |
2603 | |
2803 | |
2604 | =back |
2804 | =back |
2605 | |
2805 | |
2606 | |
2806 | |
2607 | =head1 MACRO MAGIC |
2807 | =head1 MACRO MAGIC |
2608 | |
2808 | |
2609 | Libev can be compiled with a variety of options, the most fundamantal |
2809 | Libev can be compiled with a variety of options, the most fundamental |
2610 | of which is C<EV_MULTIPLICITY>. This option determines whether (most) |
2810 | of which is C<EV_MULTIPLICITY>. This option determines whether (most) |
2611 | functions and callbacks have an initial C<struct ev_loop *> argument. |
2811 | functions and callbacks have an initial C<struct ev_loop *> argument. |
2612 | |
2812 | |
2613 | To make it easier to write programs that cope with either variant, the |
2813 | To make it easier to write programs that cope with either variant, the |
2614 | following macros are defined: |
2814 | following macros are defined: |
… | |
… | |
2619 | |
2819 | |
2620 | This provides the loop I<argument> for functions, if one is required ("ev |
2820 | This provides the loop I<argument> for functions, if one is required ("ev |
2621 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
2821 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
2622 | C<EV_A_> is used when other arguments are following. Example: |
2822 | C<EV_A_> is used when other arguments are following. Example: |
2623 | |
2823 | |
2624 | ev_unref (EV_A); |
2824 | ev_unref (EV_A); |
2625 | ev_timer_add (EV_A_ watcher); |
2825 | ev_timer_add (EV_A_ watcher); |
2626 | ev_loop (EV_A_ 0); |
2826 | ev_loop (EV_A_ 0); |
2627 | |
2827 | |
2628 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
2828 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
2629 | which is often provided by the following macro. |
2829 | which is often provided by the following macro. |
2630 | |
2830 | |
2631 | =item C<EV_P>, C<EV_P_> |
2831 | =item C<EV_P>, C<EV_P_> |
2632 | |
2832 | |
2633 | This provides the loop I<parameter> for functions, if one is required ("ev |
2833 | This provides the loop I<parameter> for functions, if one is required ("ev |
2634 | loop parameter"). The C<EV_P> form is used when this is the sole parameter, |
2834 | loop parameter"). The C<EV_P> form is used when this is the sole parameter, |
2635 | C<EV_P_> is used when other parameters are following. Example: |
2835 | C<EV_P_> is used when other parameters are following. Example: |
2636 | |
2836 | |
2637 | // this is how ev_unref is being declared |
2837 | // this is how ev_unref is being declared |
2638 | static void ev_unref (EV_P); |
2838 | static void ev_unref (EV_P); |
2639 | |
2839 | |
2640 | // this is how you can declare your typical callback |
2840 | // this is how you can declare your typical callback |
2641 | static void cb (EV_P_ ev_timer *w, int revents) |
2841 | static void cb (EV_P_ ev_timer *w, int revents) |
2642 | |
2842 | |
2643 | It declares a parameter C<loop> of type C<struct ev_loop *>, quite |
2843 | It declares a parameter C<loop> of type C<struct ev_loop *>, quite |
2644 | suitable for use with C<EV_A>. |
2844 | suitable for use with C<EV_A>. |
2645 | |
2845 | |
2646 | =item C<EV_DEFAULT>, C<EV_DEFAULT_> |
2846 | =item C<EV_DEFAULT>, C<EV_DEFAULT_> |
… | |
… | |
2662 | |
2862 | |
2663 | Example: Declare and initialise a check watcher, utilising the above |
2863 | Example: Declare and initialise a check watcher, utilising the above |
2664 | macros so it will work regardless of whether multiple loops are supported |
2864 | macros so it will work regardless of whether multiple loops are supported |
2665 | or not. |
2865 | or not. |
2666 | |
2866 | |
2667 | static void |
2867 | static void |
2668 | check_cb (EV_P_ ev_timer *w, int revents) |
2868 | check_cb (EV_P_ ev_timer *w, int revents) |
2669 | { |
2869 | { |
2670 | ev_check_stop (EV_A_ w); |
2870 | ev_check_stop (EV_A_ w); |
2671 | } |
2871 | } |
2672 | |
2872 | |
2673 | ev_check check; |
2873 | ev_check check; |
2674 | ev_check_init (&check, check_cb); |
2874 | ev_check_init (&check, check_cb); |
2675 | ev_check_start (EV_DEFAULT_ &check); |
2875 | ev_check_start (EV_DEFAULT_ &check); |
2676 | ev_loop (EV_DEFAULT_ 0); |
2876 | ev_loop (EV_DEFAULT_ 0); |
2677 | |
2877 | |
2678 | =head1 EMBEDDING |
2878 | =head1 EMBEDDING |
2679 | |
2879 | |
2680 | Libev can (and often is) directly embedded into host |
2880 | Libev can (and often is) directly embedded into host |
2681 | applications. Examples of applications that embed it include the Deliantra |
2881 | applications. Examples of applications that embed it include the Deliantra |
… | |
… | |
2688 | libev somewhere in your source tree). |
2888 | libev somewhere in your source tree). |
2689 | |
2889 | |
2690 | =head2 FILESETS |
2890 | =head2 FILESETS |
2691 | |
2891 | |
2692 | Depending on what features you need you need to include one or more sets of files |
2892 | Depending on what features you need you need to include one or more sets of files |
2693 | in your app. |
2893 | in your application. |
2694 | |
2894 | |
2695 | =head3 CORE EVENT LOOP |
2895 | =head3 CORE EVENT LOOP |
2696 | |
2896 | |
2697 | To include only the libev core (all the C<ev_*> functions), with manual |
2897 | To include only the libev core (all the C<ev_*> functions), with manual |
2698 | configuration (no autoconf): |
2898 | configuration (no autoconf): |
2699 | |
2899 | |
2700 | #define EV_STANDALONE 1 |
2900 | #define EV_STANDALONE 1 |
2701 | #include "ev.c" |
2901 | #include "ev.c" |
2702 | |
2902 | |
2703 | This will automatically include F<ev.h>, too, and should be done in a |
2903 | This will automatically include F<ev.h>, too, and should be done in a |
2704 | single C source file only to provide the function implementations. To use |
2904 | single C source file only to provide the function implementations. To use |
2705 | it, do the same for F<ev.h> in all files wishing to use this API (best |
2905 | it, do the same for F<ev.h> in all files wishing to use this API (best |
2706 | done by writing a wrapper around F<ev.h> that you can include instead and |
2906 | done by writing a wrapper around F<ev.h> that you can include instead and |
2707 | where you can put other configuration options): |
2907 | where you can put other configuration options): |
2708 | |
2908 | |
2709 | #define EV_STANDALONE 1 |
2909 | #define EV_STANDALONE 1 |
2710 | #include "ev.h" |
2910 | #include "ev.h" |
2711 | |
2911 | |
2712 | Both header files and implementation files can be compiled with a C++ |
2912 | Both header files and implementation files can be compiled with a C++ |
2713 | compiler (at least, thats a stated goal, and breakage will be treated |
2913 | compiler (at least, thats a stated goal, and breakage will be treated |
2714 | as a bug). |
2914 | as a bug). |
2715 | |
2915 | |
2716 | You need the following files in your source tree, or in a directory |
2916 | You need the following files in your source tree, or in a directory |
2717 | in your include path (e.g. in libev/ when using -Ilibev): |
2917 | in your include path (e.g. in libev/ when using -Ilibev): |
2718 | |
2918 | |
2719 | ev.h |
2919 | ev.h |
2720 | ev.c |
2920 | ev.c |
2721 | ev_vars.h |
2921 | ev_vars.h |
2722 | ev_wrap.h |
2922 | ev_wrap.h |
2723 | |
2923 | |
2724 | ev_win32.c required on win32 platforms only |
2924 | ev_win32.c required on win32 platforms only |
2725 | |
2925 | |
2726 | ev_select.c only when select backend is enabled (which is enabled by default) |
2926 | ev_select.c only when select backend is enabled (which is enabled by default) |
2727 | ev_poll.c only when poll backend is enabled (disabled by default) |
2927 | ev_poll.c only when poll backend is enabled (disabled by default) |
2728 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
2928 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
2729 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
2929 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
2730 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
2930 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
2731 | |
2931 | |
2732 | F<ev.c> includes the backend files directly when enabled, so you only need |
2932 | F<ev.c> includes the backend files directly when enabled, so you only need |
2733 | to compile this single file. |
2933 | to compile this single file. |
2734 | |
2934 | |
2735 | =head3 LIBEVENT COMPATIBILITY API |
2935 | =head3 LIBEVENT COMPATIBILITY API |
2736 | |
2936 | |
2737 | To include the libevent compatibility API, also include: |
2937 | To include the libevent compatibility API, also include: |
2738 | |
2938 | |
2739 | #include "event.c" |
2939 | #include "event.c" |
2740 | |
2940 | |
2741 | in the file including F<ev.c>, and: |
2941 | in the file including F<ev.c>, and: |
2742 | |
2942 | |
2743 | #include "event.h" |
2943 | #include "event.h" |
2744 | |
2944 | |
2745 | in the files that want to use the libevent API. This also includes F<ev.h>. |
2945 | in the files that want to use the libevent API. This also includes F<ev.h>. |
2746 | |
2946 | |
2747 | You need the following additional files for this: |
2947 | You need the following additional files for this: |
2748 | |
2948 | |
2749 | event.h |
2949 | event.h |
2750 | event.c |
2950 | event.c |
2751 | |
2951 | |
2752 | =head3 AUTOCONF SUPPORT |
2952 | =head3 AUTOCONF SUPPORT |
2753 | |
2953 | |
2754 | Instead of using C<EV_STANDALONE=1> and providing your config in |
2954 | Instead of using C<EV_STANDALONE=1> and providing your configuration in |
2755 | whatever way you want, you can also C<m4_include([libev.m4])> in your |
2955 | whatever way you want, you can also C<m4_include([libev.m4])> in your |
2756 | F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then |
2956 | F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then |
2757 | include F<config.h> and configure itself accordingly. |
2957 | include F<config.h> and configure itself accordingly. |
2758 | |
2958 | |
2759 | For this of course you need the m4 file: |
2959 | For this of course you need the m4 file: |
2760 | |
2960 | |
2761 | libev.m4 |
2961 | libev.m4 |
2762 | |
2962 | |
2763 | =head2 PREPROCESSOR SYMBOLS/MACROS |
2963 | =head2 PREPROCESSOR SYMBOLS/MACROS |
2764 | |
2964 | |
2765 | Libev can be configured via a variety of preprocessor symbols you have to |
2965 | Libev can be configured via a variety of preprocessor symbols you have to |
2766 | define before including any of its files. The default in the absense of |
2966 | define before including any of its files. The default in the absence of |
2767 | autoconf is noted for every option. |
2967 | autoconf is documented for every option. |
2768 | |
2968 | |
2769 | =over 4 |
2969 | =over 4 |
2770 | |
2970 | |
2771 | =item EV_STANDALONE |
2971 | =item EV_STANDALONE |
2772 | |
2972 | |
… | |
… | |
2777 | F<event.h> that are not directly supported by the libev core alone. |
2977 | F<event.h> that are not directly supported by the libev core alone. |
2778 | |
2978 | |
2779 | =item EV_USE_MONOTONIC |
2979 | =item EV_USE_MONOTONIC |
2780 | |
2980 | |
2781 | If defined to be C<1>, libev will try to detect the availability of the |
2981 | If defined to be C<1>, libev will try to detect the availability of the |
2782 | monotonic clock option at both compiletime and runtime. Otherwise no use |
2982 | monotonic clock option at both compile time and runtime. Otherwise no use |
2783 | of the monotonic clock option will be attempted. If you enable this, you |
2983 | of the monotonic clock option will be attempted. If you enable this, you |
2784 | usually have to link against librt or something similar. Enabling it when |
2984 | usually have to link against librt or something similar. Enabling it when |
2785 | the functionality isn't available is safe, though, although you have |
2985 | the functionality isn't available is safe, though, although you have |
2786 | to make sure you link against any libraries where the C<clock_gettime> |
2986 | to make sure you link against any libraries where the C<clock_gettime> |
2787 | function is hiding in (often F<-lrt>). |
2987 | function is hiding in (often F<-lrt>). |
2788 | |
2988 | |
2789 | =item EV_USE_REALTIME |
2989 | =item EV_USE_REALTIME |
2790 | |
2990 | |
2791 | If defined to be C<1>, libev will try to detect the availability of the |
2991 | If defined to be C<1>, libev will try to detect the availability of the |
2792 | realtime clock option at compiletime (and assume its availability at |
2992 | real-time clock option at compile time (and assume its availability at |
2793 | runtime if successful). Otherwise no use of the realtime clock option will |
2993 | runtime if successful). Otherwise no use of the real-time clock option will |
2794 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
2994 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
2795 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See the |
2995 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See the |
2796 | note about libraries in the description of C<EV_USE_MONOTONIC>, though. |
2996 | note about libraries in the description of C<EV_USE_MONOTONIC>, though. |
2797 | |
2997 | |
2798 | =item EV_USE_NANOSLEEP |
2998 | =item EV_USE_NANOSLEEP |
… | |
… | |
2809 | 2.7 or newer, otherwise disabled. |
3009 | 2.7 or newer, otherwise disabled. |
2810 | |
3010 | |
2811 | =item EV_USE_SELECT |
3011 | =item EV_USE_SELECT |
2812 | |
3012 | |
2813 | If undefined or defined to be C<1>, libev will compile in support for the |
3013 | If undefined or defined to be C<1>, libev will compile in support for the |
2814 | C<select>(2) backend. No attempt at autodetection will be done: if no |
3014 | C<select>(2) backend. No attempt at auto-detection will be done: if no |
2815 | other method takes over, select will be it. Otherwise the select backend |
3015 | other method takes over, select will be it. Otherwise the select backend |
2816 | will not be compiled in. |
3016 | will not be compiled in. |
2817 | |
3017 | |
2818 | =item EV_SELECT_USE_FD_SET |
3018 | =item EV_SELECT_USE_FD_SET |
2819 | |
3019 | |
2820 | If defined to C<1>, then the select backend will use the system C<fd_set> |
3020 | If defined to C<1>, then the select backend will use the system C<fd_set> |
2821 | structure. This is useful if libev doesn't compile due to a missing |
3021 | structure. This is useful if libev doesn't compile due to a missing |
2822 | C<NFDBITS> or C<fd_mask> definition or it misguesses the bitset layout on |
3022 | C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout on |
2823 | exotic systems. This usually limits the range of file descriptors to some |
3023 | exotic systems. This usually limits the range of file descriptors to some |
2824 | low limit such as 1024 or might have other limitations (winsocket only |
3024 | low limit such as 1024 or might have other limitations (winsocket only |
2825 | allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might |
3025 | allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might |
2826 | influence the size of the C<fd_set> used. |
3026 | influence the size of the C<fd_set> used. |
2827 | |
3027 | |
… | |
… | |
2876 | otherwise another method will be used as fallback. This is the preferred |
3076 | otherwise another method will be used as fallback. This is the preferred |
2877 | backend for Solaris 10 systems. |
3077 | backend for Solaris 10 systems. |
2878 | |
3078 | |
2879 | =item EV_USE_DEVPOLL |
3079 | =item EV_USE_DEVPOLL |
2880 | |
3080 | |
2881 | reserved for future expansion, works like the USE symbols above. |
3081 | Reserved for future expansion, works like the USE symbols above. |
2882 | |
3082 | |
2883 | =item EV_USE_INOTIFY |
3083 | =item EV_USE_INOTIFY |
2884 | |
3084 | |
2885 | If defined to be C<1>, libev will compile in support for the Linux inotify |
3085 | If defined to be C<1>, libev will compile in support for the Linux inotify |
2886 | interface to speed up C<ev_stat> watchers. Its actual availability will |
3086 | interface to speed up C<ev_stat> watchers. Its actual availability will |
… | |
… | |
2893 | access is atomic with respect to other threads or signal contexts. No such |
3093 | access is atomic with respect to other threads or signal contexts. No such |
2894 | type is easily found in the C language, so you can provide your own type |
3094 | type is easily found in the C language, so you can provide your own type |
2895 | that you know is safe for your purposes. It is used both for signal handler "locking" |
3095 | that you know is safe for your purposes. It is used both for signal handler "locking" |
2896 | as well as for signal and thread safety in C<ev_async> watchers. |
3096 | as well as for signal and thread safety in C<ev_async> watchers. |
2897 | |
3097 | |
2898 | In the absense of this define, libev will use C<sig_atomic_t volatile> |
3098 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
2899 | (from F<signal.h>), which is usually good enough on most platforms. |
3099 | (from F<signal.h>), which is usually good enough on most platforms. |
2900 | |
3100 | |
2901 | =item EV_H |
3101 | =item EV_H |
2902 | |
3102 | |
2903 | The name of the F<ev.h> header file used to include it. The default if |
3103 | The name of the F<ev.h> header file used to include it. The default if |
… | |
… | |
2942 | When doing priority-based operations, libev usually has to linearly search |
3142 | When doing priority-based operations, libev usually has to linearly search |
2943 | all the priorities, so having many of them (hundreds) uses a lot of space |
3143 | all the priorities, so having many of them (hundreds) uses a lot of space |
2944 | and time, so using the defaults of five priorities (-2 .. +2) is usually |
3144 | and time, so using the defaults of five priorities (-2 .. +2) is usually |
2945 | fine. |
3145 | fine. |
2946 | |
3146 | |
2947 | If your embedding app does not need any priorities, defining these both to |
3147 | If your embedding application does not need any priorities, defining these |
2948 | C<0> will save some memory and cpu. |
3148 | both to C<0> will save some memory and CPU. |
2949 | |
3149 | |
2950 | =item EV_PERIODIC_ENABLE |
3150 | =item EV_PERIODIC_ENABLE |
2951 | |
3151 | |
2952 | If undefined or defined to be C<1>, then periodic timers are supported. If |
3152 | If undefined or defined to be C<1>, then periodic timers are supported. If |
2953 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
3153 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
… | |
… | |
2960 | code. |
3160 | code. |
2961 | |
3161 | |
2962 | =item EV_EMBED_ENABLE |
3162 | =item EV_EMBED_ENABLE |
2963 | |
3163 | |
2964 | If undefined or defined to be C<1>, then embed watchers are supported. If |
3164 | If undefined or defined to be C<1>, then embed watchers are supported. If |
2965 | defined to be C<0>, then they are not. |
3165 | defined to be C<0>, then they are not. Embed watchers rely on most other |
|
|
3166 | watcher types, which therefore must not be disabled. |
2966 | |
3167 | |
2967 | =item EV_STAT_ENABLE |
3168 | =item EV_STAT_ENABLE |
2968 | |
3169 | |
2969 | If undefined or defined to be C<1>, then stat watchers are supported. If |
3170 | If undefined or defined to be C<1>, then stat watchers are supported. If |
2970 | defined to be C<0>, then they are not. |
3171 | defined to be C<0>, then they are not. |
… | |
… | |
2981 | |
3182 | |
2982 | =item EV_MINIMAL |
3183 | =item EV_MINIMAL |
2983 | |
3184 | |
2984 | If you need to shave off some kilobytes of code at the expense of some |
3185 | If you need to shave off some kilobytes of code at the expense of some |
2985 | speed, define this symbol to C<1>. Currently this is used to override some |
3186 | speed, define this symbol to C<1>. Currently this is used to override some |
2986 | inlining decisions, saves roughly 30% codesize of amd64. It also selects a |
3187 | inlining decisions, saves roughly 30% code size on amd64. It also selects a |
2987 | much smaller 2-heap for timer management over the default 4-heap. |
3188 | much smaller 2-heap for timer management over the default 4-heap. |
2988 | |
3189 | |
2989 | =item EV_PID_HASHSIZE |
3190 | =item EV_PID_HASHSIZE |
2990 | |
3191 | |
2991 | C<ev_child> watchers use a small hash table to distribute workload by |
3192 | C<ev_child> watchers use a small hash table to distribute workload by |
… | |
… | |
3002 | two). |
3203 | two). |
3003 | |
3204 | |
3004 | =item EV_USE_4HEAP |
3205 | =item EV_USE_4HEAP |
3005 | |
3206 | |
3006 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3207 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3007 | timer and periodics heap, libev uses a 4-heap when this symbol is defined |
3208 | timer and periodics heaps, libev uses a 4-heap when this symbol is defined |
3008 | to C<1>. The 4-heap uses more complicated (longer) code but has a |
3209 | to C<1>. The 4-heap uses more complicated (longer) code but has noticeably |
3009 | noticable after performance with many (thousands) of watchers. |
3210 | faster performance with many (thousands) of watchers. |
3010 | |
3211 | |
3011 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
3212 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
3012 | (disabled). |
3213 | (disabled). |
3013 | |
3214 | |
3014 | =item EV_HEAP_CACHE_AT |
3215 | =item EV_HEAP_CACHE_AT |
3015 | |
3216 | |
3016 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3217 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3017 | timer and periodics heap, libev can cache the timestamp (I<at>) within |
3218 | timer and periodics heaps, libev can cache the timestamp (I<at>) within |
3018 | the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>), |
3219 | the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>), |
3019 | which uses 8-12 bytes more per watcher and a few hundred bytes more code, |
3220 | which uses 8-12 bytes more per watcher and a few hundred bytes more code, |
3020 | but avoids random read accesses on heap changes. This noticably improves |
3221 | but avoids random read accesses on heap changes. This improves performance |
3021 | performance noticably with with many (hundreds) of watchers. |
3222 | noticeably with many (hundreds) of watchers. |
3022 | |
3223 | |
3023 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
3224 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
3024 | (disabled). |
3225 | (disabled). |
|
|
3226 | |
|
|
3227 | =item EV_VERIFY |
|
|
3228 | |
|
|
3229 | Controls how much internal verification (see C<ev_loop_verify ()>) will |
|
|
3230 | be done: If set to C<0>, no internal verification code will be compiled |
|
|
3231 | in. If set to C<1>, then verification code will be compiled in, but not |
|
|
3232 | called. If set to C<2>, then the internal verification code will be |
|
|
3233 | called once per loop, which can slow down libev. If set to C<3>, then the |
|
|
3234 | verification code will be called very frequently, which will slow down |
|
|
3235 | libev considerably. |
|
|
3236 | |
|
|
3237 | The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be |
|
|
3238 | C<0>. |
3025 | |
3239 | |
3026 | =item EV_COMMON |
3240 | =item EV_COMMON |
3027 | |
3241 | |
3028 | By default, all watchers have a C<void *data> member. By redefining |
3242 | By default, all watchers have a C<void *data> member. By redefining |
3029 | this macro to a something else you can include more and other types of |
3243 | this macro to a something else you can include more and other types of |
3030 | members. You have to define it each time you include one of the files, |
3244 | members. You have to define it each time you include one of the files, |
3031 | though, and it must be identical each time. |
3245 | though, and it must be identical each time. |
3032 | |
3246 | |
3033 | For example, the perl EV module uses something like this: |
3247 | For example, the perl EV module uses something like this: |
3034 | |
3248 | |
3035 | #define EV_COMMON \ |
3249 | #define EV_COMMON \ |
3036 | SV *self; /* contains this struct */ \ |
3250 | SV *self; /* contains this struct */ \ |
3037 | SV *cb_sv, *fh /* note no trailing ";" */ |
3251 | SV *cb_sv, *fh /* note no trailing ";" */ |
3038 | |
3252 | |
3039 | =item EV_CB_DECLARE (type) |
3253 | =item EV_CB_DECLARE (type) |
3040 | |
3254 | |
3041 | =item EV_CB_INVOKE (watcher, revents) |
3255 | =item EV_CB_INVOKE (watcher, revents) |
3042 | |
3256 | |
… | |
… | |
3047 | definition and a statement, respectively. See the F<ev.h> header file for |
3261 | definition and a statement, respectively. See the F<ev.h> header file for |
3048 | their default definitions. One possible use for overriding these is to |
3262 | their default definitions. One possible use for overriding these is to |
3049 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
3263 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
3050 | method calls instead of plain function calls in C++. |
3264 | method calls instead of plain function calls in C++. |
3051 | |
3265 | |
|
|
3266 | =back |
|
|
3267 | |
3052 | =head2 EXPORTED API SYMBOLS |
3268 | =head2 EXPORTED API SYMBOLS |
3053 | |
3269 | |
3054 | If you need to re-export the API (e.g. via a dll) and you need a list of |
3270 | If you need to re-export the API (e.g. via a DLL) and you need a list of |
3055 | exported symbols, you can use the provided F<Symbol.*> files which list |
3271 | exported symbols, you can use the provided F<Symbol.*> files which list |
3056 | all public symbols, one per line: |
3272 | all public symbols, one per line: |
3057 | |
3273 | |
3058 | Symbols.ev for libev proper |
3274 | Symbols.ev for libev proper |
3059 | Symbols.event for the libevent emulation |
3275 | Symbols.event for the libevent emulation |
3060 | |
3276 | |
3061 | This can also be used to rename all public symbols to avoid clashes with |
3277 | This can also be used to rename all public symbols to avoid clashes with |
3062 | multiple versions of libev linked together (which is obviously bad in |
3278 | multiple versions of libev linked together (which is obviously bad in |
3063 | itself, but sometimes it is inconvinient to avoid this). |
3279 | itself, but sometimes it is inconvenient to avoid this). |
3064 | |
3280 | |
3065 | A sed command like this will create wrapper C<#define>'s that you need to |
3281 | A sed command like this will create wrapper C<#define>'s that you need to |
3066 | include before including F<ev.h>: |
3282 | include before including F<ev.h>: |
3067 | |
3283 | |
3068 | <Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h |
3284 | <Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h |
… | |
… | |
3085 | file. |
3301 | file. |
3086 | |
3302 | |
3087 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
3303 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
3088 | that everybody includes and which overrides some configure choices: |
3304 | that everybody includes and which overrides some configure choices: |
3089 | |
3305 | |
3090 | #define EV_MINIMAL 1 |
3306 | #define EV_MINIMAL 1 |
3091 | #define EV_USE_POLL 0 |
3307 | #define EV_USE_POLL 0 |
3092 | #define EV_MULTIPLICITY 0 |
3308 | #define EV_MULTIPLICITY 0 |
3093 | #define EV_PERIODIC_ENABLE 0 |
3309 | #define EV_PERIODIC_ENABLE 0 |
3094 | #define EV_STAT_ENABLE 0 |
3310 | #define EV_STAT_ENABLE 0 |
3095 | #define EV_FORK_ENABLE 0 |
3311 | #define EV_FORK_ENABLE 0 |
3096 | #define EV_CONFIG_H <config.h> |
3312 | #define EV_CONFIG_H <config.h> |
3097 | #define EV_MINPRI 0 |
3313 | #define EV_MINPRI 0 |
3098 | #define EV_MAXPRI 0 |
3314 | #define EV_MAXPRI 0 |
3099 | |
3315 | |
3100 | #include "ev++.h" |
3316 | #include "ev++.h" |
3101 | |
3317 | |
3102 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
3318 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
3103 | |
3319 | |
3104 | #include "ev_cpp.h" |
3320 | #include "ev_cpp.h" |
3105 | #include "ev.c" |
3321 | #include "ev.c" |
3106 | |
3322 | |
|
|
3323 | =head1 INTERACTION WITH OTHER PROGRAMS OR LIBRARIES |
3107 | |
3324 | |
3108 | =head1 THREADS AND COROUTINES |
3325 | =head2 THREADS AND COROUTINES |
3109 | |
3326 | |
3110 | =head2 THREADS |
3327 | =head3 THREADS |
3111 | |
3328 | |
3112 | Libev itself is completely threadsafe, but it uses no locking. This |
3329 | All libev functions are reentrant and thread-safe unless explicitly |
|
|
3330 | documented otherwise, but libev implements no locking itself. This means |
3113 | means that you can use as many loops as you want in parallel, as long as |
3331 | that you can use as many loops as you want in parallel, as long as there |
3114 | only one thread ever calls into one libev function with the same loop |
3332 | are no concurrent calls into any libev function with the same loop |
3115 | parameter. |
3333 | parameter (C<ev_default_*> calls have an implicit default loop parameter, |
|
|
3334 | of course): libev guarantees that different event loops share no data |
|
|
3335 | structures that need any locking. |
3116 | |
3336 | |
3117 | Or put differently: calls with different loop parameters can be done in |
3337 | Or to put it differently: calls with different loop parameters can be done |
3118 | parallel from multiple threads, calls with the same loop parameter must be |
3338 | concurrently from multiple threads, calls with the same loop parameter |
3119 | done serially (but can be done from different threads, as long as only one |
3339 | must be done serially (but can be done from different threads, as long as |
3120 | thread ever is inside a call at any point in time, e.g. by using a mutex |
3340 | only one thread ever is inside a call at any point in time, e.g. by using |
3121 | per loop). |
3341 | a mutex per loop). |
3122 | |
3342 | |
3123 | If you want to know which design is best for your problem, then I cannot |
3343 | Specifically to support threads (and signal handlers), libev implements |
|
|
3344 | so-called C<ev_async> watchers, which allow some limited form of |
|
|
3345 | concurrency on the same event loop, namely waking it up "from the |
|
|
3346 | outside". |
|
|
3347 | |
|
|
3348 | If you want to know which design (one loop, locking, or multiple loops |
|
|
3349 | without or something else still) is best for your problem, then I cannot |
3124 | help you but by giving some generic advice: |
3350 | help you, but here is some generic advice: |
3125 | |
3351 | |
3126 | =over 4 |
3352 | =over 4 |
3127 | |
3353 | |
3128 | =item * most applications have a main thread: use the default libev loop |
3354 | =item * most applications have a main thread: use the default libev loop |
3129 | in that thread, or create a seperate thread running only the default loop. |
3355 | in that thread, or create a separate thread running only the default loop. |
3130 | |
3356 | |
3131 | This helps integrating other libraries or software modules that use libev |
3357 | This helps integrating other libraries or software modules that use libev |
3132 | themselves and don't care/know about threading. |
3358 | themselves and don't care/know about threading. |
3133 | |
3359 | |
3134 | =item * one loop per thread is usually a good model. |
3360 | =item * one loop per thread is usually a good model. |
3135 | |
3361 | |
3136 | Doing this is almost never wrong, sometimes a better-performance model |
3362 | Doing this is almost never wrong, sometimes a better-performance model |
3137 | exists, but it is always a good start. |
3363 | exists, but it is always a good start. |
3138 | |
3364 | |
3139 | =item * other models exist, such as the leader/follower pattern, where one |
3365 | =item * other models exist, such as the leader/follower pattern, where one |
3140 | loop is handed through multiple threads in a kind of round-robbin fashion. |
3366 | loop is handed through multiple threads in a kind of round-robin fashion. |
3141 | |
3367 | |
3142 | Chosing a model is hard - look around, learn, know that usually you cna do |
3368 | Choosing a model is hard - look around, learn, know that usually you can do |
3143 | better than you currently do :-) |
3369 | better than you currently do :-) |
3144 | |
3370 | |
3145 | =item * often you need to talk to some other thread which blocks in the |
3371 | =item * often you need to talk to some other thread which blocks in the |
|
|
3372 | event loop. |
|
|
3373 | |
3146 | event loop - C<ev_async> watchers can be used to wake them up from other |
3374 | C<ev_async> watchers can be used to wake them up from other threads safely |
3147 | threads safely (or from signal contexts...). |
3375 | (or from signal contexts...). |
|
|
3376 | |
|
|
3377 | An example use would be to communicate signals or other events that only |
|
|
3378 | work in the default loop by registering the signal watcher with the |
|
|
3379 | default loop and triggering an C<ev_async> watcher from the default loop |
|
|
3380 | watcher callback into the event loop interested in the signal. |
3148 | |
3381 | |
3149 | =back |
3382 | =back |
3150 | |
3383 | |
3151 | =head2 COROUTINES |
3384 | =head3 COROUTINES |
3152 | |
3385 | |
3153 | Libev is much more accomodating to coroutines ("cooperative threads"): |
3386 | Libev is very accommodating to coroutines ("cooperative threads"): |
3154 | libev fully supports nesting calls to it's functions from different |
3387 | libev fully supports nesting calls to its functions from different |
3155 | coroutines (e.g. you can call C<ev_loop> on the same loop from two |
3388 | coroutines (e.g. you can call C<ev_loop> on the same loop from two |
3156 | different coroutines and switch freely between both coroutines running the |
3389 | different coroutines, and switch freely between both coroutines running the |
3157 | loop, as long as you don't confuse yourself). The only exception is that |
3390 | loop, as long as you don't confuse yourself). The only exception is that |
3158 | you must not do this from C<ev_periodic> reschedule callbacks. |
3391 | you must not do this from C<ev_periodic> reschedule callbacks. |
3159 | |
3392 | |
3160 | Care has been invested into making sure that libev does not keep local |
3393 | Care has been taken to ensure that libev does not keep local state inside |
3161 | state inside C<ev_loop>, and other calls do not usually allow coroutine |
3394 | C<ev_loop>, and other calls do not usually allow for coroutine switches as |
3162 | switches. |
3395 | they do not clal any callbacks. |
3163 | |
3396 | |
|
|
3397 | =head2 COMPILER WARNINGS |
3164 | |
3398 | |
3165 | =head1 COMPLEXITIES |
3399 | Depending on your compiler and compiler settings, you might get no or a |
|
|
3400 | lot of warnings when compiling libev code. Some people are apparently |
|
|
3401 | scared by this. |
3166 | |
3402 | |
3167 | In this section the complexities of (many of) the algorithms used inside |
3403 | However, these are unavoidable for many reasons. For one, each compiler |
3168 | libev will be explained. For complexity discussions about backends see the |
3404 | has different warnings, and each user has different tastes regarding |
3169 | documentation for C<ev_default_init>. |
3405 | warning options. "Warn-free" code therefore cannot be a goal except when |
|
|
3406 | targeting a specific compiler and compiler-version. |
3170 | |
3407 | |
3171 | All of the following are about amortised time: If an array needs to be |
3408 | Another reason is that some compiler warnings require elaborate |
3172 | extended, libev needs to realloc and move the whole array, but this |
3409 | workarounds, or other changes to the code that make it less clear and less |
3173 | happens asymptotically never with higher number of elements, so O(1) might |
3410 | maintainable. |
3174 | mean it might do a lengthy realloc operation in rare cases, but on average |
|
|
3175 | it is much faster and asymptotically approaches constant time. |
|
|
3176 | |
3411 | |
3177 | =over 4 |
3412 | And of course, some compiler warnings are just plain stupid, or simply |
|
|
3413 | wrong (because they don't actually warn about the condition their message |
|
|
3414 | seems to warn about). For example, certain older gcc versions had some |
|
|
3415 | warnings that resulted an extreme number of false positives. These have |
|
|
3416 | been fixed, but some people still insist on making code warn-free with |
|
|
3417 | such buggy versions. |
3178 | |
3418 | |
3179 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
3419 | While libev is written to generate as few warnings as possible, |
|
|
3420 | "warn-free" code is not a goal, and it is recommended not to build libev |
|
|
3421 | with any compiler warnings enabled unless you are prepared to cope with |
|
|
3422 | them (e.g. by ignoring them). Remember that warnings are just that: |
|
|
3423 | warnings, not errors, or proof of bugs. |
3180 | |
3424 | |
3181 | This means that, when you have a watcher that triggers in one hour and |
|
|
3182 | there are 100 watchers that would trigger before that then inserting will |
|
|
3183 | have to skip roughly seven (C<ld 100>) of these watchers. |
|
|
3184 | |
3425 | |
3185 | =item Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers) |
3426 | =head2 VALGRIND |
3186 | |
3427 | |
3187 | That means that changing a timer costs less than removing/adding them |
3428 | Valgrind has a special section here because it is a popular tool that is |
3188 | as only the relative motion in the event queue has to be paid for. |
3429 | highly useful. Unfortunately, valgrind reports are very hard to interpret. |
3189 | |
3430 | |
3190 | =item Starting io/check/prepare/idle/signal/child/fork/async watchers: O(1) |
3431 | If you think you found a bug (memory leak, uninitialised data access etc.) |
|
|
3432 | in libev, then check twice: If valgrind reports something like: |
3191 | |
3433 | |
3192 | These just add the watcher into an array or at the head of a list. |
3434 | ==2274== definitely lost: 0 bytes in 0 blocks. |
|
|
3435 | ==2274== possibly lost: 0 bytes in 0 blocks. |
|
|
3436 | ==2274== still reachable: 256 bytes in 1 blocks. |
3193 | |
3437 | |
3194 | =item Stopping check/prepare/idle/fork/async watchers: O(1) |
3438 | Then there is no memory leak, just as memory accounted to global variables |
|
|
3439 | is not a memleak - the memory is still being refernced, and didn't leak. |
3195 | |
3440 | |
3196 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
3441 | Similarly, under some circumstances, valgrind might report kernel bugs |
|
|
3442 | as if it were a bug in libev (e.g. in realloc or in the poll backend, |
|
|
3443 | although an acceptable workaround has been found here), or it might be |
|
|
3444 | confused. |
3197 | |
3445 | |
3198 | These watchers are stored in lists then need to be walked to find the |
3446 | Keep in mind that valgrind is a very good tool, but only a tool. Don't |
3199 | correct watcher to remove. The lists are usually short (you don't usually |
3447 | make it into some kind of religion. |
3200 | have many watchers waiting for the same fd or signal). |
|
|
3201 | |
3448 | |
3202 | =item Finding the next timer in each loop iteration: O(1) |
3449 | If you are unsure about something, feel free to contact the mailing list |
|
|
3450 | with the full valgrind report and an explanation on why you think this |
|
|
3451 | is a bug in libev (best check the archives, too :). However, don't be |
|
|
3452 | annoyed when you get a brisk "this is no bug" answer and take the chance |
|
|
3453 | of learning how to interpret valgrind properly. |
3203 | |
3454 | |
3204 | By virtue of using a binary or 4-heap, the next timer is always found at a |
3455 | If you need, for some reason, empty reports from valgrind for your project |
3205 | fixed position in the storage array. |
3456 | I suggest using suppression lists. |
3206 | |
3457 | |
3207 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
|
|
3208 | |
3458 | |
3209 | A change means an I/O watcher gets started or stopped, which requires |
3459 | =head1 PORTABILITY NOTES |
3210 | libev to recalculate its status (and possibly tell the kernel, depending |
|
|
3211 | on backend and wether C<ev_io_set> was used). |
|
|
3212 | |
3460 | |
3213 | =item Activating one watcher (putting it into the pending state): O(1) |
3461 | =head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS |
3214 | |
|
|
3215 | =item Priority handling: O(number_of_priorities) |
|
|
3216 | |
|
|
3217 | Priorities are implemented by allocating some space for each |
|
|
3218 | priority. When doing priority-based operations, libev usually has to |
|
|
3219 | linearly search all the priorities, but starting/stopping and activating |
|
|
3220 | watchers becomes O(1) w.r.t. priority handling. |
|
|
3221 | |
|
|
3222 | =item Sending an ev_async: O(1) |
|
|
3223 | |
|
|
3224 | =item Processing ev_async_send: O(number_of_async_watchers) |
|
|
3225 | |
|
|
3226 | =item Processing signals: O(max_signal_number) |
|
|
3227 | |
|
|
3228 | Sending involves a syscall I<iff> there were no other C<ev_async_send> |
|
|
3229 | calls in the current loop iteration. Checking for async and signal events |
|
|
3230 | involves iterating over all running async watchers or all signal numbers. |
|
|
3231 | |
|
|
3232 | =back |
|
|
3233 | |
|
|
3234 | |
|
|
3235 | =head1 Win32 platform limitations and workarounds |
|
|
3236 | |
3462 | |
3237 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
3463 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
3238 | requires, and its I/O model is fundamentally incompatible with the POSIX |
3464 | requires, and its I/O model is fundamentally incompatible with the POSIX |
3239 | model. Libev still offers limited functionality on this platform in |
3465 | model. Libev still offers limited functionality on this platform in |
3240 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
3466 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
… | |
… | |
3247 | way (note also that glib is the slowest event library known to man). |
3473 | way (note also that glib is the slowest event library known to man). |
3248 | |
3474 | |
3249 | There is no supported compilation method available on windows except |
3475 | There is no supported compilation method available on windows except |
3250 | embedding it into other applications. |
3476 | embedding it into other applications. |
3251 | |
3477 | |
|
|
3478 | Not a libev limitation but worth mentioning: windows apparently doesn't |
|
|
3479 | accept large writes: instead of resulting in a partial write, windows will |
|
|
3480 | either accept everything or return C<ENOBUFS> if the buffer is too large, |
|
|
3481 | so make sure you only write small amounts into your sockets (less than a |
|
|
3482 | megabyte seems safe, but this apparently depends on the amount of memory |
|
|
3483 | available). |
|
|
3484 | |
3252 | Due to the many, low, and arbitrary limits on the win32 platform and |
3485 | Due to the many, low, and arbitrary limits on the win32 platform and |
3253 | the abysmal performance of winsockets, using a large number of sockets |
3486 | the abysmal performance of winsockets, using a large number of sockets |
3254 | is not recommended (and not reasonable). If your program needs to use |
3487 | is not recommended (and not reasonable). If your program needs to use |
3255 | more than a hundred or so sockets, then likely it needs to use a totally |
3488 | more than a hundred or so sockets, then likely it needs to use a totally |
3256 | different implementation for windows, as libev offers the POSIX readyness |
3489 | different implementation for windows, as libev offers the POSIX readiness |
3257 | notification model, which cannot be implemented efficiently on windows |
3490 | notification model, which cannot be implemented efficiently on windows |
3258 | (microsoft monopoly games). |
3491 | (Microsoft monopoly games). |
|
|
3492 | |
|
|
3493 | A typical way to use libev under windows is to embed it (see the embedding |
|
|
3494 | section for details) and use the following F<evwrap.h> header file instead |
|
|
3495 | of F<ev.h>: |
|
|
3496 | |
|
|
3497 | #define EV_STANDALONE /* keeps ev from requiring config.h */ |
|
|
3498 | #define EV_SELECT_IS_WINSOCKET 1 /* configure libev for windows select */ |
|
|
3499 | |
|
|
3500 | #include "ev.h" |
|
|
3501 | |
|
|
3502 | And compile the following F<evwrap.c> file into your project (make sure |
|
|
3503 | you do I<not> compile the F<ev.c> or any other embedded source files!): |
|
|
3504 | |
|
|
3505 | #include "evwrap.h" |
|
|
3506 | #include "ev.c" |
3259 | |
3507 | |
3260 | =over 4 |
3508 | =over 4 |
3261 | |
3509 | |
3262 | =item The winsocket select function |
3510 | =item The winsocket select function |
3263 | |
3511 | |
3264 | The winsocket C<select> function doesn't follow POSIX in that it requires |
3512 | The winsocket C<select> function doesn't follow POSIX in that it |
3265 | socket I<handles> and not socket I<file descriptors>. This makes select |
3513 | requires socket I<handles> and not socket I<file descriptors> (it is |
3266 | very inefficient, and also requires a mapping from file descriptors |
3514 | also extremely buggy). This makes select very inefficient, and also |
3267 | to socket handles. See the discussion of the C<EV_SELECT_USE_FD_SET>, |
3515 | requires a mapping from file descriptors to socket handles (the Microsoft |
3268 | C<EV_SELECT_IS_WINSOCKET> and C<EV_FD_TO_WIN32_HANDLE> preprocessor |
3516 | C runtime provides the function C<_open_osfhandle> for this). See the |
3269 | symbols for more info. |
3517 | discussion of the C<EV_SELECT_USE_FD_SET>, C<EV_SELECT_IS_WINSOCKET> and |
|
|
3518 | C<EV_FD_TO_WIN32_HANDLE> preprocessor symbols for more info. |
3270 | |
3519 | |
3271 | The configuration for a "naked" win32 using the microsoft runtime |
3520 | The configuration for a "naked" win32 using the Microsoft runtime |
3272 | libraries and raw winsocket select is: |
3521 | libraries and raw winsocket select is: |
3273 | |
3522 | |
3274 | #define EV_USE_SELECT 1 |
3523 | #define EV_USE_SELECT 1 |
3275 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
3524 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
3276 | |
3525 | |
3277 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
3526 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
3278 | complexity in the O(n²) range when using win32. |
3527 | complexity in the O(n²) range when using win32. |
3279 | |
3528 | |
3280 | =item Limited number of file descriptors |
3529 | =item Limited number of file descriptors |
3281 | |
3530 | |
3282 | Windows has numerous arbitrary (and low) limits on things. |
3531 | Windows has numerous arbitrary (and low) limits on things. |
3283 | |
3532 | |
3284 | Early versions of winsocket's select only supported waiting for a maximum |
3533 | Early versions of winsocket's select only supported waiting for a maximum |
3285 | of C<64> handles (probably owning to the fact that all windows kernels |
3534 | of C<64> handles (probably owning to the fact that all windows kernels |
3286 | can only wait for C<64> things at the same time internally; microsoft |
3535 | can only wait for C<64> things at the same time internally; Microsoft |
3287 | recommends spawning a chain of threads and wait for 63 handles and the |
3536 | recommends spawning a chain of threads and wait for 63 handles and the |
3288 | previous thread in each. Great). |
3537 | previous thread in each. Great). |
3289 | |
3538 | |
3290 | Newer versions support more handles, but you need to define C<FD_SETSIZE> |
3539 | Newer versions support more handles, but you need to define C<FD_SETSIZE> |
3291 | to some high number (e.g. C<2048>) before compiling the winsocket select |
3540 | to some high number (e.g. C<2048>) before compiling the winsocket select |
3292 | call (which might be in libev or elsewhere, for example, perl does its own |
3541 | call (which might be in libev or elsewhere, for example, perl does its own |
3293 | select emulation on windows). |
3542 | select emulation on windows). |
3294 | |
3543 | |
3295 | Another limit is the number of file descriptors in the microsoft runtime |
3544 | Another limit is the number of file descriptors in the Microsoft runtime |
3296 | libraries, which by default is C<64> (there must be a hidden I<64> fetish |
3545 | libraries, which by default is C<64> (there must be a hidden I<64> fetish |
3297 | or something like this inside microsoft). You can increase this by calling |
3546 | or something like this inside Microsoft). You can increase this by calling |
3298 | C<_setmaxstdio>, which can increase this limit to C<2048> (another |
3547 | C<_setmaxstdio>, which can increase this limit to C<2048> (another |
3299 | arbitrary limit), but is broken in many versions of the microsoft runtime |
3548 | arbitrary limit), but is broken in many versions of the Microsoft runtime |
3300 | libraries. |
3549 | libraries. |
3301 | |
3550 | |
3302 | This might get you to about C<512> or C<2048> sockets (depending on |
3551 | This might get you to about C<512> or C<2048> sockets (depending on |
3303 | windows version and/or the phase of the moon). To get more, you need to |
3552 | windows version and/or the phase of the moon). To get more, you need to |
3304 | wrap all I/O functions and provide your own fd management, but the cost of |
3553 | wrap all I/O functions and provide your own fd management, but the cost of |
3305 | calling select (O(n²)) will likely make this unworkable. |
3554 | calling select (O(n²)) will likely make this unworkable. |
3306 | |
3555 | |
3307 | =back |
3556 | =back |
3308 | |
3557 | |
3309 | |
|
|
3310 | =head1 PORTABILITY REQUIREMENTS |
3558 | =head2 PORTABILITY REQUIREMENTS |
3311 | |
3559 | |
3312 | In addition to a working ISO-C implementation, libev relies on a few |
3560 | In addition to a working ISO-C implementation and of course the |
3313 | additional extensions: |
3561 | backend-specific APIs, libev relies on a few additional extensions: |
3314 | |
3562 | |
3315 | =over 4 |
3563 | =over 4 |
3316 | |
3564 | |
|
|
3565 | =item C<void (*)(ev_watcher_type *, int revents)> must have compatible |
|
|
3566 | calling conventions regardless of C<ev_watcher_type *>. |
|
|
3567 | |
|
|
3568 | Libev assumes not only that all watcher pointers have the same internal |
|
|
3569 | structure (guaranteed by POSIX but not by ISO C for example), but it also |
|
|
3570 | assumes that the same (machine) code can be used to call any watcher |
|
|
3571 | callback: The watcher callbacks have different type signatures, but libev |
|
|
3572 | calls them using an C<ev_watcher *> internally. |
|
|
3573 | |
3317 | =item C<sig_atomic_t volatile> must be thread-atomic as well |
3574 | =item C<sig_atomic_t volatile> must be thread-atomic as well |
3318 | |
3575 | |
3319 | The type C<sig_atomic_t volatile> (or whatever is defined as |
3576 | The type C<sig_atomic_t volatile> (or whatever is defined as |
3320 | C<EV_ATOMIC_T>) must be atomic w.r.t. accesses from different |
3577 | C<EV_ATOMIC_T>) must be atomic with respect to accesses from different |
3321 | threads. This is not part of the specification for C<sig_atomic_t>, but is |
3578 | threads. This is not part of the specification for C<sig_atomic_t>, but is |
3322 | believed to be sufficiently portable. |
3579 | believed to be sufficiently portable. |
3323 | |
3580 | |
3324 | =item C<sigprocmask> must work in a threaded environment |
3581 | =item C<sigprocmask> must work in a threaded environment |
3325 | |
3582 | |
… | |
… | |
3334 | except the initial one, and run the default loop in the initial thread as |
3591 | except the initial one, and run the default loop in the initial thread as |
3335 | well. |
3592 | well. |
3336 | |
3593 | |
3337 | =item C<long> must be large enough for common memory allocation sizes |
3594 | =item C<long> must be large enough for common memory allocation sizes |
3338 | |
3595 | |
3339 | To improve portability and simplify using libev, libev uses C<long> |
3596 | To improve portability and simplify its API, libev uses C<long> internally |
3340 | internally instead of C<size_t> when allocating its data structures. On |
3597 | instead of C<size_t> when allocating its data structures. On non-POSIX |
3341 | non-POSIX systems (Microsoft...) this might be unexpectedly low, but |
3598 | systems (Microsoft...) this might be unexpectedly low, but is still at |
3342 | is still at least 31 bits everywhere, which is enough for hundreds of |
3599 | least 31 bits everywhere, which is enough for hundreds of millions of |
3343 | millions of watchers. |
3600 | watchers. |
3344 | |
3601 | |
3345 | =item C<double> must hold a time value in seconds with enough accuracy |
3602 | =item C<double> must hold a time value in seconds with enough accuracy |
3346 | |
3603 | |
3347 | The type C<double> is used to represent timestamps. It is required to |
3604 | The type C<double> is used to represent timestamps. It is required to |
3348 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
3605 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
… | |
… | |
3352 | =back |
3609 | =back |
3353 | |
3610 | |
3354 | If you know of other additional requirements drop me a note. |
3611 | If you know of other additional requirements drop me a note. |
3355 | |
3612 | |
3356 | |
3613 | |
|
|
3614 | =head1 ALGORITHMIC COMPLEXITIES |
|
|
3615 | |
|
|
3616 | In this section the complexities of (many of) the algorithms used inside |
|
|
3617 | libev will be documented. For complexity discussions about backends see |
|
|
3618 | the documentation for C<ev_default_init>. |
|
|
3619 | |
|
|
3620 | All of the following are about amortised time: If an array needs to be |
|
|
3621 | extended, libev needs to realloc and move the whole array, but this |
|
|
3622 | happens asymptotically rarer with higher number of elements, so O(1) might |
|
|
3623 | mean that libev does a lengthy realloc operation in rare cases, but on |
|
|
3624 | average it is much faster and asymptotically approaches constant time. |
|
|
3625 | |
|
|
3626 | =over 4 |
|
|
3627 | |
|
|
3628 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
|
|
3629 | |
|
|
3630 | This means that, when you have a watcher that triggers in one hour and |
|
|
3631 | there are 100 watchers that would trigger before that, then inserting will |
|
|
3632 | have to skip roughly seven (C<ld 100>) of these watchers. |
|
|
3633 | |
|
|
3634 | =item Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers) |
|
|
3635 | |
|
|
3636 | That means that changing a timer costs less than removing/adding them, |
|
|
3637 | as only the relative motion in the event queue has to be paid for. |
|
|
3638 | |
|
|
3639 | =item Starting io/check/prepare/idle/signal/child/fork/async watchers: O(1) |
|
|
3640 | |
|
|
3641 | These just add the watcher into an array or at the head of a list. |
|
|
3642 | |
|
|
3643 | =item Stopping check/prepare/idle/fork/async watchers: O(1) |
|
|
3644 | |
|
|
3645 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
|
|
3646 | |
|
|
3647 | These watchers are stored in lists, so they need to be walked to find the |
|
|
3648 | correct watcher to remove. The lists are usually short (you don't usually |
|
|
3649 | have many watchers waiting for the same fd or signal: one is typical, two |
|
|
3650 | is rare). |
|
|
3651 | |
|
|
3652 | =item Finding the next timer in each loop iteration: O(1) |
|
|
3653 | |
|
|
3654 | By virtue of using a binary or 4-heap, the next timer is always found at a |
|
|
3655 | fixed position in the storage array. |
|
|
3656 | |
|
|
3657 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
|
|
3658 | |
|
|
3659 | A change means an I/O watcher gets started or stopped, which requires |
|
|
3660 | libev to recalculate its status (and possibly tell the kernel, depending |
|
|
3661 | on backend and whether C<ev_io_set> was used). |
|
|
3662 | |
|
|
3663 | =item Activating one watcher (putting it into the pending state): O(1) |
|
|
3664 | |
|
|
3665 | =item Priority handling: O(number_of_priorities) |
|
|
3666 | |
|
|
3667 | Priorities are implemented by allocating some space for each |
|
|
3668 | priority. When doing priority-based operations, libev usually has to |
|
|
3669 | linearly search all the priorities, but starting/stopping and activating |
|
|
3670 | watchers becomes O(1) with respect to priority handling. |
|
|
3671 | |
|
|
3672 | =item Sending an ev_async: O(1) |
|
|
3673 | |
|
|
3674 | =item Processing ev_async_send: O(number_of_async_watchers) |
|
|
3675 | |
|
|
3676 | =item Processing signals: O(max_signal_number) |
|
|
3677 | |
|
|
3678 | Sending involves a system call I<iff> there were no other C<ev_async_send> |
|
|
3679 | calls in the current loop iteration. Checking for async and signal events |
|
|
3680 | involves iterating over all running async watchers or all signal numbers. |
|
|
3681 | |
|
|
3682 | =back |
|
|
3683 | |
|
|
3684 | |
3357 | =head1 AUTHOR |
3685 | =head1 AUTHOR |
3358 | |
3686 | |
3359 | Marc Lehmann <libev@schmorp.de>. |
3687 | Marc Lehmann <libev@schmorp.de>. |
3360 | |
3688 | |