… | |
… | |
4 | |
4 | |
5 | =head1 SYNOPSIS |
5 | =head1 SYNOPSIS |
6 | |
6 | |
7 | #include <ev.h> |
7 | #include <ev.h> |
8 | |
8 | |
|
|
9 | =head2 EXAMPLE PROGRAM |
|
|
10 | |
|
|
11 | #include <ev.h> |
|
|
12 | |
|
|
13 | ev_io stdin_watcher; |
|
|
14 | ev_timer timeout_watcher; |
|
|
15 | |
|
|
16 | /* called when data readable on stdin */ |
|
|
17 | static void |
|
|
18 | stdin_cb (EV_P_ struct ev_io *w, int revents) |
|
|
19 | { |
|
|
20 | /* puts ("stdin ready"); */ |
|
|
21 | ev_io_stop (EV_A_ w); /* just a syntax example */ |
|
|
22 | ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */ |
|
|
23 | } |
|
|
24 | |
|
|
25 | static void |
|
|
26 | timeout_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
27 | { |
|
|
28 | /* puts ("timeout"); */ |
|
|
29 | ev_unloop (EV_A_ EVUNLOOP_ONE); /* leave one loop call */ |
|
|
30 | } |
|
|
31 | |
|
|
32 | int |
|
|
33 | main (void) |
|
|
34 | { |
|
|
35 | struct ev_loop *loop = ev_default_loop (0); |
|
|
36 | |
|
|
37 | /* initialise an io watcher, then start it */ |
|
|
38 | ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
|
|
39 | ev_io_start (loop, &stdin_watcher); |
|
|
40 | |
|
|
41 | /* simple non-repeating 5.5 second timeout */ |
|
|
42 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
|
|
43 | ev_timer_start (loop, &timeout_watcher); |
|
|
44 | |
|
|
45 | /* loop till timeout or data ready */ |
|
|
46 | ev_loop (loop, 0); |
|
|
47 | |
|
|
48 | return 0; |
|
|
49 | } |
|
|
50 | |
9 | =head1 DESCRIPTION |
51 | =head1 DESCRIPTION |
10 | |
52 | |
|
|
53 | The newest version of this document is also available as a html-formatted |
|
|
54 | web page you might find easier to navigate when reading it for the first |
|
|
55 | time: L<http://cvs.schmorp.de/libev/ev.html>. |
|
|
56 | |
11 | Libev is an event loop: you register interest in certain events (such as a |
57 | Libev is an event loop: you register interest in certain events (such as a |
12 | file descriptor being readable or a timeout occuring), and it will manage |
58 | file descriptor being readable or a timeout occurring), and it will manage |
13 | these event sources and provide your program with events. |
59 | these event sources and provide your program with events. |
14 | |
60 | |
15 | To do this, it must take more or less complete control over your process |
61 | To do this, it must take more or less complete control over your process |
16 | (or thread) by executing the I<event loop> handler, and will then |
62 | (or thread) by executing the I<event loop> handler, and will then |
17 | communicate events via a callback mechanism. |
63 | communicate events via a callback mechanism. |
… | |
… | |
19 | You register interest in certain events by registering so-called I<event |
65 | You register interest in certain events by registering so-called I<event |
20 | watchers>, which are relatively small C structures you initialise with the |
66 | watchers>, which are relatively small C structures you initialise with the |
21 | details of the event, and then hand it over to libev by I<starting> the |
67 | details of the event, and then hand it over to libev by I<starting> the |
22 | watcher. |
68 | watcher. |
23 | |
69 | |
24 | =head1 FEATURES |
70 | =head2 FEATURES |
25 | |
71 | |
26 | Libev supports select, poll, the linux-specific epoll and the bsd-specific |
72 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
27 | kqueue mechanisms for file descriptor events, relative timers, absolute |
73 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
28 | timers with customised rescheduling, signal events, process status change |
74 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
29 | events (related to SIGCHLD), and event watchers dealing with the event |
75 | (for C<ev_stat>), relative timers (C<ev_timer>), absolute timers |
30 | loop mechanism itself (idle, prepare and check watchers). It also is quite |
76 | with customised rescheduling (C<ev_periodic>), synchronous signals |
|
|
77 | (C<ev_signal>), process status change events (C<ev_child>), and event |
|
|
78 | watchers dealing with the event loop mechanism itself (C<ev_idle>, |
|
|
79 | C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as |
|
|
80 | file watchers (C<ev_stat>) and even limited support for fork events |
|
|
81 | (C<ev_fork>). |
|
|
82 | |
|
|
83 | It also is quite fast (see this |
31 | fast (see this L<benchmark|http://libev.schmorp.de/bench.html> comparing |
84 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
32 | it to libevent for example). |
85 | for example). |
33 | |
86 | |
34 | =head1 CONVENTIONS |
87 | =head2 CONVENTIONS |
35 | |
88 | |
36 | Libev is very configurable. In this manual the default configuration |
89 | Libev is very configurable. In this manual the default configuration will |
37 | will be described, which supports multiple event loops. For more info |
90 | be described, which supports multiple event loops. For more info about |
38 | about various configuration options please have a look at the file |
91 | various configuration options please have a look at B<EMBED> section in |
39 | F<README.embed> in the libev distribution. If libev was configured without |
92 | this manual. If libev was configured without support for multiple event |
40 | support for multiple event loops, then all functions taking an initial |
93 | loops, then all functions taking an initial argument of name C<loop> |
41 | argument of name C<loop> (which is always of type C<struct ev_loop *>) |
94 | (which is always of type C<struct ev_loop *>) will not have this argument. |
42 | will not have this argument. |
|
|
43 | |
95 | |
44 | =head1 TIME AND OTHER GLOBAL FUNCTIONS |
96 | =head2 TIME REPRESENTATION |
45 | |
97 | |
46 | Libev represents time as a single floating point number, representing the |
98 | Libev represents time as a single floating point number, representing the |
47 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
99 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
48 | the beginning of 1970, details are complicated, don't ask). This type is |
100 | the beginning of 1970, details are complicated, don't ask). This type is |
49 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
101 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
50 | to the double type in C. |
102 | to the C<double> type in C, and when you need to do any calculations on |
|
|
103 | it, you should treat it as some floatingpoint value. Unlike the name |
|
|
104 | component C<stamp> might indicate, it is also used for time differences |
|
|
105 | throughout libev. |
|
|
106 | |
|
|
107 | =head1 GLOBAL FUNCTIONS |
|
|
108 | |
|
|
109 | These functions can be called anytime, even before initialising the |
|
|
110 | library in any way. |
51 | |
111 | |
52 | =over 4 |
112 | =over 4 |
53 | |
113 | |
54 | =item ev_tstamp ev_time () |
114 | =item ev_tstamp ev_time () |
55 | |
115 | |
56 | Returns the current time as libev would use it. |
116 | Returns the current time as libev would use it. Please note that the |
|
|
117 | C<ev_now> function is usually faster and also often returns the timestamp |
|
|
118 | you actually want to know. |
|
|
119 | |
|
|
120 | =item ev_sleep (ev_tstamp interval) |
|
|
121 | |
|
|
122 | Sleep for the given interval: The current thread will be blocked until |
|
|
123 | either it is interrupted or the given time interval has passed. Basically |
|
|
124 | this is a subsecond-resolution C<sleep ()>. |
57 | |
125 | |
58 | =item int ev_version_major () |
126 | =item int ev_version_major () |
59 | |
127 | |
60 | =item int ev_version_minor () |
128 | =item int ev_version_minor () |
61 | |
129 | |
62 | You can find out the major and minor version numbers of the library |
130 | You can find out the major and minor ABI version numbers of the library |
63 | you linked against by calling the functions C<ev_version_major> and |
131 | you linked against by calling the functions C<ev_version_major> and |
64 | C<ev_version_minor>. If you want, you can compare against the global |
132 | C<ev_version_minor>. If you want, you can compare against the global |
65 | symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the |
133 | symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the |
66 | version of the library your program was compiled against. |
134 | version of the library your program was compiled against. |
67 | |
135 | |
|
|
136 | These version numbers refer to the ABI version of the library, not the |
|
|
137 | release version. |
|
|
138 | |
68 | Usually, it's a good idea to terminate if the major versions mismatch, |
139 | Usually, it's a good idea to terminate if the major versions mismatch, |
69 | as this indicates an incompatible change. Minor versions are usually |
140 | as this indicates an incompatible change. Minor versions are usually |
70 | compatible to older versions, so a larger minor version alone is usually |
141 | compatible to older versions, so a larger minor version alone is usually |
71 | not a problem. |
142 | not a problem. |
72 | |
143 | |
|
|
144 | Example: Make sure we haven't accidentally been linked against the wrong |
|
|
145 | version. |
|
|
146 | |
|
|
147 | assert (("libev version mismatch", |
|
|
148 | ev_version_major () == EV_VERSION_MAJOR |
|
|
149 | && ev_version_minor () >= EV_VERSION_MINOR)); |
|
|
150 | |
|
|
151 | =item unsigned int ev_supported_backends () |
|
|
152 | |
|
|
153 | Return the set of all backends (i.e. their corresponding C<EV_BACKEND_*> |
|
|
154 | value) compiled into this binary of libev (independent of their |
|
|
155 | availability on the system you are running on). See C<ev_default_loop> for |
|
|
156 | a description of the set values. |
|
|
157 | |
|
|
158 | Example: make sure we have the epoll method, because yeah this is cool and |
|
|
159 | a must have and can we have a torrent of it please!!!11 |
|
|
160 | |
|
|
161 | assert (("sorry, no epoll, no sex", |
|
|
162 | ev_supported_backends () & EVBACKEND_EPOLL)); |
|
|
163 | |
|
|
164 | =item unsigned int ev_recommended_backends () |
|
|
165 | |
|
|
166 | Return the set of all backends compiled into this binary of libev and also |
|
|
167 | recommended for this platform. This set is often smaller than the one |
|
|
168 | returned by C<ev_supported_backends>, as for example kqueue is broken on |
|
|
169 | most BSDs and will not be autodetected unless you explicitly request it |
|
|
170 | (assuming you know what you are doing). This is the set of backends that |
|
|
171 | libev will probe for if you specify no backends explicitly. |
|
|
172 | |
|
|
173 | =item unsigned int ev_embeddable_backends () |
|
|
174 | |
|
|
175 | Returns the set of backends that are embeddable in other event loops. This |
|
|
176 | is the theoretical, all-platform, value. To find which backends |
|
|
177 | might be supported on the current system, you would need to look at |
|
|
178 | C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for |
|
|
179 | recommended ones. |
|
|
180 | |
|
|
181 | See the description of C<ev_embed> watchers for more info. |
|
|
182 | |
73 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
183 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
74 | |
184 | |
75 | Sets the allocation function to use (the prototype is similar to the |
185 | Sets the allocation function to use (the prototype is similar - the |
76 | realloc C function, the semantics are identical). It is used to allocate |
186 | semantics is identical - to the realloc C function). It is used to |
77 | and free memory (no surprises here). If it returns zero when memory |
187 | allocate and free memory (no surprises here). If it returns zero when |
78 | needs to be allocated, the library might abort or take some potentially |
188 | memory needs to be allocated, the library might abort or take some |
79 | destructive action. The default is your system realloc function. |
189 | potentially destructive action. The default is your system realloc |
|
|
190 | function. |
80 | |
191 | |
81 | You could override this function in high-availability programs to, say, |
192 | You could override this function in high-availability programs to, say, |
82 | free some memory if it cannot allocate memory, to use a special allocator, |
193 | free some memory if it cannot allocate memory, to use a special allocator, |
83 | or even to sleep a while and retry until some memory is available. |
194 | or even to sleep a while and retry until some memory is available. |
|
|
195 | |
|
|
196 | Example: Replace the libev allocator with one that waits a bit and then |
|
|
197 | retries). |
|
|
198 | |
|
|
199 | static void * |
|
|
200 | persistent_realloc (void *ptr, size_t size) |
|
|
201 | { |
|
|
202 | for (;;) |
|
|
203 | { |
|
|
204 | void *newptr = realloc (ptr, size); |
|
|
205 | |
|
|
206 | if (newptr) |
|
|
207 | return newptr; |
|
|
208 | |
|
|
209 | sleep (60); |
|
|
210 | } |
|
|
211 | } |
|
|
212 | |
|
|
213 | ... |
|
|
214 | ev_set_allocator (persistent_realloc); |
84 | |
215 | |
85 | =item ev_set_syserr_cb (void (*cb)(const char *msg)); |
216 | =item ev_set_syserr_cb (void (*cb)(const char *msg)); |
86 | |
217 | |
87 | Set the callback function to call on a retryable syscall error (such |
218 | Set the callback function to call on a retryable syscall error (such |
88 | as failed select, poll, epoll_wait). The message is a printable string |
219 | as failed select, poll, epoll_wait). The message is a printable string |
… | |
… | |
90 | callback is set, then libev will expect it to remedy the sitution, no |
221 | callback is set, then libev will expect it to remedy the sitution, no |
91 | matter what, when it returns. That is, libev will generally retry the |
222 | matter what, when it returns. That is, libev will generally retry the |
92 | requested operation, or, if the condition doesn't go away, do bad stuff |
223 | requested operation, or, if the condition doesn't go away, do bad stuff |
93 | (such as abort). |
224 | (such as abort). |
94 | |
225 | |
|
|
226 | Example: This is basically the same thing that libev does internally, too. |
|
|
227 | |
|
|
228 | static void |
|
|
229 | fatal_error (const char *msg) |
|
|
230 | { |
|
|
231 | perror (msg); |
|
|
232 | abort (); |
|
|
233 | } |
|
|
234 | |
|
|
235 | ... |
|
|
236 | ev_set_syserr_cb (fatal_error); |
|
|
237 | |
95 | =back |
238 | =back |
96 | |
239 | |
97 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
240 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
98 | |
241 | |
99 | An event loop is described by a C<struct ev_loop *>. The library knows two |
242 | An event loop is described by a C<struct ev_loop *>. The library knows two |
100 | types of such loops, the I<default> loop, which supports signals and child |
243 | types of such loops, the I<default> loop, which supports signals and child |
101 | events, and dynamically created loops which do not. |
244 | events, and dynamically created loops which do not. |
102 | |
245 | |
103 | If you use threads, a common model is to run the default event loop |
246 | If you use threads, a common model is to run the default event loop |
104 | in your main thread (or in a separate thrad) and for each thread you |
247 | in your main thread (or in a separate thread) and for each thread you |
105 | create, you also create another event loop. Libev itself does no locking |
248 | create, you also create another event loop. Libev itself does no locking |
106 | whatsoever, so if you mix calls to the same event loop in different |
249 | whatsoever, so if you mix calls to the same event loop in different |
107 | threads, make sure you lock (this is usually a bad idea, though, even if |
250 | threads, make sure you lock (this is usually a bad idea, though, even if |
108 | done correctly, because it's hideous and inefficient). |
251 | done correctly, because it's hideous and inefficient). |
109 | |
252 | |
… | |
… | |
112 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
255 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
113 | |
256 | |
114 | This will initialise the default event loop if it hasn't been initialised |
257 | This will initialise the default event loop if it hasn't been initialised |
115 | yet and return it. If the default loop could not be initialised, returns |
258 | yet and return it. If the default loop could not be initialised, returns |
116 | false. If it already was initialised it simply returns it (and ignores the |
259 | false. If it already was initialised it simply returns it (and ignores the |
117 | flags). |
260 | flags. If that is troubling you, check C<ev_backend ()> afterwards). |
118 | |
261 | |
119 | If you don't know what event loop to use, use the one returned from this |
262 | If you don't know what event loop to use, use the one returned from this |
120 | function. |
263 | function. |
121 | |
264 | |
|
|
265 | The default loop is the only loop that can handle C<ev_signal> and |
|
|
266 | C<ev_child> watchers, and to do this, it always registers a handler |
|
|
267 | for C<SIGCHLD>. If this is a problem for your app you can either |
|
|
268 | create a dynamic loop with C<ev_loop_new> that doesn't do that, or you |
|
|
269 | can simply overwrite the C<SIGCHLD> signal handler I<after> calling |
|
|
270 | C<ev_default_init>. |
|
|
271 | |
122 | The flags argument can be used to specify special behaviour or specific |
272 | The flags argument can be used to specify special behaviour or specific |
123 | backends to use, and is usually specified as 0 (or EVFLAG_AUTO). |
273 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
124 | |
274 | |
125 | It supports the following flags: |
275 | The following flags are supported: |
126 | |
276 | |
127 | =over 4 |
277 | =over 4 |
128 | |
278 | |
129 | =item C<EVFLAG_AUTO> |
279 | =item C<EVFLAG_AUTO> |
130 | |
280 | |
… | |
… | |
138 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
288 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
139 | override the flags completely if it is found in the environment. This is |
289 | override the flags completely if it is found in the environment. This is |
140 | useful to try out specific backends to test their performance, or to work |
290 | useful to try out specific backends to test their performance, or to work |
141 | around bugs. |
291 | around bugs. |
142 | |
292 | |
|
|
293 | =item C<EVFLAG_FORKCHECK> |
|
|
294 | |
|
|
295 | Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after |
|
|
296 | a fork, you can also make libev check for a fork in each iteration by |
|
|
297 | enabling this flag. |
|
|
298 | |
|
|
299 | This works by calling C<getpid ()> on every iteration of the loop, |
|
|
300 | and thus this might slow down your event loop if you do a lot of loop |
|
|
301 | iterations and little real work, but is usually not noticeable (on my |
|
|
302 | Linux system for example, C<getpid> is actually a simple 5-insn sequence |
|
|
303 | without a syscall and thus I<very> fast, but my Linux system also has |
|
|
304 | C<pthread_atfork> which is even faster). |
|
|
305 | |
|
|
306 | The big advantage of this flag is that you can forget about fork (and |
|
|
307 | forget about forgetting to tell libev about forking) when you use this |
|
|
308 | flag. |
|
|
309 | |
|
|
310 | This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS> |
|
|
311 | environment variable. |
|
|
312 | |
143 | =item C<EVMETHOD_SELECT> (portable select backend) |
313 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
144 | |
314 | |
|
|
315 | This is your standard select(2) backend. Not I<completely> standard, as |
|
|
316 | libev tries to roll its own fd_set with no limits on the number of fds, |
|
|
317 | but if that fails, expect a fairly low limit on the number of fds when |
|
|
318 | using this backend. It doesn't scale too well (O(highest_fd)), but its |
|
|
319 | usually the fastest backend for a low number of (low-numbered :) fds. |
|
|
320 | |
|
|
321 | To get good performance out of this backend you need a high amount of |
|
|
322 | parallelity (most of the file descriptors should be busy). If you are |
|
|
323 | writing a server, you should C<accept ()> in a loop to accept as many |
|
|
324 | connections as possible during one iteration. You might also want to have |
|
|
325 | a look at C<ev_set_io_collect_interval ()> to increase the amount of |
|
|
326 | readyness notifications you get per iteration. |
|
|
327 | |
145 | =item C<EVMETHOD_POLL> (poll backend, available everywhere except on windows) |
328 | =item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows) |
146 | |
329 | |
147 | =item C<EVMETHOD_EPOLL> (linux only) |
330 | And this is your standard poll(2) backend. It's more complicated |
|
|
331 | than select, but handles sparse fds better and has no artificial |
|
|
332 | limit on the number of fds you can use (except it will slow down |
|
|
333 | considerably with a lot of inactive fds). It scales similarly to select, |
|
|
334 | i.e. O(total_fds). See the entry for C<EVBACKEND_SELECT>, above, for |
|
|
335 | performance tips. |
148 | |
336 | |
149 | =item C<EVMETHOD_KQUEUE> (some bsds only) |
337 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
150 | |
338 | |
151 | =item C<EVMETHOD_DEVPOLL> (solaris 8 only) |
339 | For few fds, this backend is a bit little slower than poll and select, |
|
|
340 | but it scales phenomenally better. While poll and select usually scale |
|
|
341 | like O(total_fds) where n is the total number of fds (or the highest fd), |
|
|
342 | epoll scales either O(1) or O(active_fds). The epoll design has a number |
|
|
343 | of shortcomings, such as silently dropping events in some hard-to-detect |
|
|
344 | cases and rewiring a syscall per fd change, no fork support and bad |
|
|
345 | support for dup. |
152 | |
346 | |
153 | =item C<EVMETHOD_PORT> (solaris 10 only) |
347 | While stopping, setting and starting an I/O watcher in the same iteration |
|
|
348 | will result in some caching, there is still a syscall per such incident |
|
|
349 | (because the fd could point to a different file description now), so its |
|
|
350 | best to avoid that. Also, C<dup ()>'ed file descriptors might not work |
|
|
351 | very well if you register events for both fds. |
|
|
352 | |
|
|
353 | Please note that epoll sometimes generates spurious notifications, so you |
|
|
354 | need to use non-blocking I/O or other means to avoid blocking when no data |
|
|
355 | (or space) is available. |
|
|
356 | |
|
|
357 | Best performance from this backend is achieved by not unregistering all |
|
|
358 | watchers for a file descriptor until it has been closed, if possible, i.e. |
|
|
359 | keep at least one watcher active per fd at all times. |
|
|
360 | |
|
|
361 | While nominally embeddeble in other event loops, this feature is broken in |
|
|
362 | all kernel versions tested so far. |
|
|
363 | |
|
|
364 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
|
|
365 | |
|
|
366 | Kqueue deserves special mention, as at the time of this writing, it |
|
|
367 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
|
|
368 | with anything but sockets and pipes, except on Darwin, where of course |
|
|
369 | it's completely useless). For this reason it's not being "autodetected" |
|
|
370 | unless you explicitly specify it explicitly in the flags (i.e. using |
|
|
371 | C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough) |
|
|
372 | system like NetBSD. |
|
|
373 | |
|
|
374 | You still can embed kqueue into a normal poll or select backend and use it |
|
|
375 | only for sockets (after having made sure that sockets work with kqueue on |
|
|
376 | the target platform). See C<ev_embed> watchers for more info. |
|
|
377 | |
|
|
378 | It scales in the same way as the epoll backend, but the interface to the |
|
|
379 | kernel is more efficient (which says nothing about its actual speed, of |
|
|
380 | course). While stopping, setting and starting an I/O watcher does never |
|
|
381 | cause an extra syscall as with C<EVBACKEND_EPOLL>, it still adds up to |
|
|
382 | two event changes per incident, support for C<fork ()> is very bad and it |
|
|
383 | drops fds silently in similarly hard-to-detect cases. |
|
|
384 | |
|
|
385 | This backend usually performs well under most conditions. |
|
|
386 | |
|
|
387 | While nominally embeddable in other event loops, this doesn't work |
|
|
388 | everywhere, so you might need to test for this. And since it is broken |
|
|
389 | almost everywhere, you should only use it when you have a lot of sockets |
|
|
390 | (for which it usually works), by embedding it into another event loop |
|
|
391 | (e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>) and using it only for |
|
|
392 | sockets. |
|
|
393 | |
|
|
394 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
|
|
395 | |
|
|
396 | This is not implemented yet (and might never be, unless you send me an |
|
|
397 | implementation). According to reports, C</dev/poll> only supports sockets |
|
|
398 | and is not embeddable, which would limit the usefulness of this backend |
|
|
399 | immensely. |
|
|
400 | |
|
|
401 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
|
|
402 | |
|
|
403 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
|
|
404 | it's really slow, but it still scales very well (O(active_fds)). |
|
|
405 | |
|
|
406 | Please note that solaris event ports can deliver a lot of spurious |
|
|
407 | notifications, so you need to use non-blocking I/O or other means to avoid |
|
|
408 | blocking when no data (or space) is available. |
|
|
409 | |
|
|
410 | While this backend scales well, it requires one system call per active |
|
|
411 | file descriptor per loop iteration. For small and medium numbers of file |
|
|
412 | descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend |
|
|
413 | might perform better. |
|
|
414 | |
|
|
415 | On the positive side, ignoring the spurious readyness notifications, this |
|
|
416 | backend actually performed to specification in all tests and is fully |
|
|
417 | embeddable, which is a rare feat among the OS-specific backends. |
|
|
418 | |
|
|
419 | =item C<EVBACKEND_ALL> |
|
|
420 | |
|
|
421 | Try all backends (even potentially broken ones that wouldn't be tried |
|
|
422 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
|
|
423 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
|
|
424 | |
|
|
425 | It is definitely not recommended to use this flag. |
|
|
426 | |
|
|
427 | =back |
154 | |
428 | |
155 | If one or more of these are ored into the flags value, then only these |
429 | If one or more of these are ored into the flags value, then only these |
156 | backends will be tried (in the reverse order as given here). If one are |
430 | backends will be tried (in the reverse order as listed here). If none are |
157 | specified, any backend will do. |
431 | specified, all backends in C<ev_recommended_backends ()> will be tried. |
158 | |
432 | |
159 | =back |
433 | The most typical usage is like this: |
|
|
434 | |
|
|
435 | if (!ev_default_loop (0)) |
|
|
436 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
|
|
437 | |
|
|
438 | Restrict libev to the select and poll backends, and do not allow |
|
|
439 | environment settings to be taken into account: |
|
|
440 | |
|
|
441 | ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
|
|
442 | |
|
|
443 | Use whatever libev has to offer, but make sure that kqueue is used if |
|
|
444 | available (warning, breaks stuff, best use only with your own private |
|
|
445 | event loop and only if you know the OS supports your types of fds): |
|
|
446 | |
|
|
447 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
160 | |
448 | |
161 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
449 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
162 | |
450 | |
163 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
451 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
164 | always distinct from the default loop. Unlike the default loop, it cannot |
452 | always distinct from the default loop. Unlike the default loop, it cannot |
165 | handle signal and child watchers, and attempts to do so will be greeted by |
453 | handle signal and child watchers, and attempts to do so will be greeted by |
166 | undefined behaviour (or a failed assertion if assertions are enabled). |
454 | undefined behaviour (or a failed assertion if assertions are enabled). |
167 | |
455 | |
|
|
456 | Example: Try to create a event loop that uses epoll and nothing else. |
|
|
457 | |
|
|
458 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
|
|
459 | if (!epoller) |
|
|
460 | fatal ("no epoll found here, maybe it hides under your chair"); |
|
|
461 | |
168 | =item ev_default_destroy () |
462 | =item ev_default_destroy () |
169 | |
463 | |
170 | Destroys the default loop again (frees all memory and kernel state |
464 | Destroys the default loop again (frees all memory and kernel state |
171 | etc.). This stops all registered event watchers (by not touching them in |
465 | etc.). None of the active event watchers will be stopped in the normal |
172 | any way whatsoever, although you cannot rely on this :). |
466 | sense, so e.g. C<ev_is_active> might still return true. It is your |
|
|
467 | responsibility to either stop all watchers cleanly yoursef I<before> |
|
|
468 | calling this function, or cope with the fact afterwards (which is usually |
|
|
469 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
|
|
470 | for example). |
|
|
471 | |
|
|
472 | Note that certain global state, such as signal state, will not be freed by |
|
|
473 | this function, and related watchers (such as signal and child watchers) |
|
|
474 | would need to be stopped manually. |
|
|
475 | |
|
|
476 | In general it is not advisable to call this function except in the |
|
|
477 | rare occasion where you really need to free e.g. the signal handling |
|
|
478 | pipe fds. If you need dynamically allocated loops it is better to use |
|
|
479 | C<ev_loop_new> and C<ev_loop_destroy>). |
173 | |
480 | |
174 | =item ev_loop_destroy (loop) |
481 | =item ev_loop_destroy (loop) |
175 | |
482 | |
176 | Like C<ev_default_destroy>, but destroys an event loop created by an |
483 | Like C<ev_default_destroy>, but destroys an event loop created by an |
177 | earlier call to C<ev_loop_new>. |
484 | earlier call to C<ev_loop_new>. |
178 | |
485 | |
179 | =item ev_default_fork () |
486 | =item ev_default_fork () |
180 | |
487 | |
|
|
488 | This function sets a flag that causes subsequent C<ev_loop> iterations |
181 | This function reinitialises the kernel state for backends that have |
489 | to reinitialise the kernel state for backends that have one. Despite the |
182 | one. Despite the name, you can call it anytime, but it makes most sense |
490 | name, you can call it anytime, but it makes most sense after forking, in |
183 | after forking, in either the parent or child process (or both, but that |
491 | the child process (or both child and parent, but that again makes little |
184 | again makes little sense). |
492 | sense). You I<must> call it in the child before using any of the libev |
|
|
493 | functions, and it will only take effect at the next C<ev_loop> iteration. |
185 | |
494 | |
186 | You I<must> call this function after forking if and only if you want to |
495 | On the other hand, you only need to call this function in the child |
187 | use the event library in both processes. If you just fork+exec, you don't |
496 | process if and only if you want to use the event library in the child. If |
188 | have to call it. |
497 | you just fork+exec, you don't have to call it at all. |
189 | |
498 | |
190 | The function itself is quite fast and it's usually not a problem to call |
499 | The function itself is quite fast and it's usually not a problem to call |
191 | it just in case after a fork. To make this easy, the function will fit in |
500 | it just in case after a fork. To make this easy, the function will fit in |
192 | quite nicely into a call to C<pthread_atfork>: |
501 | quite nicely into a call to C<pthread_atfork>: |
193 | |
502 | |
… | |
… | |
197 | |
506 | |
198 | Like C<ev_default_fork>, but acts on an event loop created by |
507 | Like C<ev_default_fork>, but acts on an event loop created by |
199 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
508 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
200 | after fork, and how you do this is entirely your own problem. |
509 | after fork, and how you do this is entirely your own problem. |
201 | |
510 | |
|
|
511 | =item unsigned int ev_loop_count (loop) |
|
|
512 | |
|
|
513 | Returns the count of loop iterations for the loop, which is identical to |
|
|
514 | the number of times libev did poll for new events. It starts at C<0> and |
|
|
515 | happily wraps around with enough iterations. |
|
|
516 | |
|
|
517 | This value can sometimes be useful as a generation counter of sorts (it |
|
|
518 | "ticks" the number of loop iterations), as it roughly corresponds with |
|
|
519 | C<ev_prepare> and C<ev_check> calls. |
|
|
520 | |
202 | =item unsigned int ev_method (loop) |
521 | =item unsigned int ev_backend (loop) |
203 | |
522 | |
204 | Returns one of the C<EVMETHOD_*> flags indicating the event backend in |
523 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
205 | use. |
524 | use. |
206 | |
525 | |
207 | =item ev_tstamp ev_now (loop) |
526 | =item ev_tstamp ev_now (loop) |
208 | |
527 | |
209 | Returns the current "event loop time", which is the time the event loop |
528 | Returns the current "event loop time", which is the time the event loop |
210 | got events and started processing them. This timestamp does not change |
529 | received events and started processing them. This timestamp does not |
211 | as long as callbacks are being processed, and this is also the base time |
530 | change as long as callbacks are being processed, and this is also the base |
212 | used for relative timers. You can treat it as the timestamp of the event |
531 | time used for relative timers. You can treat it as the timestamp of the |
213 | occuring (or more correctly, the mainloop finding out about it). |
532 | event occurring (or more correctly, libev finding out about it). |
214 | |
533 | |
215 | =item ev_loop (loop, int flags) |
534 | =item ev_loop (loop, int flags) |
216 | |
535 | |
217 | Finally, this is it, the event handler. This function usually is called |
536 | Finally, this is it, the event handler. This function usually is called |
218 | after you initialised all your watchers and you want to start handling |
537 | after you initialised all your watchers and you want to start handling |
219 | events. |
538 | events. |
220 | |
539 | |
221 | If the flags argument is specified as 0, it will not return until either |
540 | If the flags argument is specified as C<0>, it will not return until |
222 | no event watchers are active anymore or C<ev_unloop> was called. |
541 | either no event watchers are active anymore or C<ev_unloop> was called. |
|
|
542 | |
|
|
543 | Please note that an explicit C<ev_unloop> is usually better than |
|
|
544 | relying on all watchers to be stopped when deciding when a program has |
|
|
545 | finished (especially in interactive programs), but having a program that |
|
|
546 | automatically loops as long as it has to and no longer by virtue of |
|
|
547 | relying on its watchers stopping correctly is a thing of beauty. |
223 | |
548 | |
224 | A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle |
549 | A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle |
225 | those events and any outstanding ones, but will not block your process in |
550 | those events and any outstanding ones, but will not block your process in |
226 | case there are no events and will return after one iteration of the loop. |
551 | case there are no events and will return after one iteration of the loop. |
227 | |
552 | |
228 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
553 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
229 | neccessary) and will handle those and any outstanding ones. It will block |
554 | neccessary) and will handle those and any outstanding ones. It will block |
230 | your process until at least one new event arrives, and will return after |
555 | your process until at least one new event arrives, and will return after |
231 | one iteration of the loop. |
556 | one iteration of the loop. This is useful if you are waiting for some |
|
|
557 | external event in conjunction with something not expressible using other |
|
|
558 | libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is |
|
|
559 | usually a better approach for this kind of thing. |
232 | |
560 | |
233 | This flags value could be used to implement alternative looping |
561 | Here are the gory details of what C<ev_loop> does: |
234 | constructs, but the C<prepare> and C<check> watchers provide a better and |
562 | |
235 | more generic mechanism. |
563 | - Before the first iteration, call any pending watchers. |
|
|
564 | * If EVFLAG_FORKCHECK was used, check for a fork. |
|
|
565 | - If a fork was detected, queue and call all fork watchers. |
|
|
566 | - Queue and call all prepare watchers. |
|
|
567 | - If we have been forked, recreate the kernel state. |
|
|
568 | - Update the kernel state with all outstanding changes. |
|
|
569 | - Update the "event loop time". |
|
|
570 | - Calculate for how long to sleep or block, if at all |
|
|
571 | (active idle watchers, EVLOOP_NONBLOCK or not having |
|
|
572 | any active watchers at all will result in not sleeping). |
|
|
573 | - Sleep if the I/O and timer collect interval say so. |
|
|
574 | - Block the process, waiting for any events. |
|
|
575 | - Queue all outstanding I/O (fd) events. |
|
|
576 | - Update the "event loop time" and do time jump handling. |
|
|
577 | - Queue all outstanding timers. |
|
|
578 | - Queue all outstanding periodics. |
|
|
579 | - If no events are pending now, queue all idle watchers. |
|
|
580 | - Queue all check watchers. |
|
|
581 | - Call all queued watchers in reverse order (i.e. check watchers first). |
|
|
582 | Signals and child watchers are implemented as I/O watchers, and will |
|
|
583 | be handled here by queueing them when their watcher gets executed. |
|
|
584 | - If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
|
|
585 | were used, or there are no active watchers, return, otherwise |
|
|
586 | continue with step *. |
|
|
587 | |
|
|
588 | Example: Queue some jobs and then loop until no events are outstanding |
|
|
589 | anymore. |
|
|
590 | |
|
|
591 | ... queue jobs here, make sure they register event watchers as long |
|
|
592 | ... as they still have work to do (even an idle watcher will do..) |
|
|
593 | ev_loop (my_loop, 0); |
|
|
594 | ... jobs done. yeah! |
236 | |
595 | |
237 | =item ev_unloop (loop, how) |
596 | =item ev_unloop (loop, how) |
238 | |
597 | |
239 | Can be used to make a call to C<ev_loop> return early (but only after it |
598 | Can be used to make a call to C<ev_loop> return early (but only after it |
240 | has processed all outstanding events). The C<how> argument must be either |
599 | has processed all outstanding events). The C<how> argument must be either |
241 | C<EVUNLOOP_ONCE>, which will make the innermost C<ev_loop> call return, or |
600 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
242 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
601 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
|
|
602 | |
|
|
603 | This "unloop state" will be cleared when entering C<ev_loop> again. |
243 | |
604 | |
244 | =item ev_ref (loop) |
605 | =item ev_ref (loop) |
245 | |
606 | |
246 | =item ev_unref (loop) |
607 | =item ev_unref (loop) |
247 | |
608 | |
… | |
… | |
252 | returning, ev_unref() after starting, and ev_ref() before stopping it. For |
613 | returning, ev_unref() after starting, and ev_ref() before stopping it. For |
253 | example, libev itself uses this for its internal signal pipe: It is not |
614 | example, libev itself uses this for its internal signal pipe: It is not |
254 | visible to the libev user and should not keep C<ev_loop> from exiting if |
615 | visible to the libev user and should not keep C<ev_loop> from exiting if |
255 | no event watchers registered by it are active. It is also an excellent |
616 | no event watchers registered by it are active. It is also an excellent |
256 | way to do this for generic recurring timers or from within third-party |
617 | way to do this for generic recurring timers or from within third-party |
257 | libraries. Just remember to I<unref after start> and I<ref before stop>. |
618 | libraries. Just remember to I<unref after start> and I<ref before stop> |
|
|
619 | (but only if the watcher wasn't active before, or was active before, |
|
|
620 | respectively). |
|
|
621 | |
|
|
622 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
|
|
623 | running when nothing else is active. |
|
|
624 | |
|
|
625 | struct ev_signal exitsig; |
|
|
626 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
|
|
627 | ev_signal_start (loop, &exitsig); |
|
|
628 | evf_unref (loop); |
|
|
629 | |
|
|
630 | Example: For some weird reason, unregister the above signal handler again. |
|
|
631 | |
|
|
632 | ev_ref (loop); |
|
|
633 | ev_signal_stop (loop, &exitsig); |
|
|
634 | |
|
|
635 | =item ev_set_io_collect_interval (loop, ev_tstamp interval) |
|
|
636 | |
|
|
637 | =item ev_set_timeout_collect_interval (loop, ev_tstamp interval) |
|
|
638 | |
|
|
639 | These advanced functions influence the time that libev will spend waiting |
|
|
640 | for events. Both are by default C<0>, meaning that libev will try to |
|
|
641 | invoke timer/periodic callbacks and I/O callbacks with minimum latency. |
|
|
642 | |
|
|
643 | Setting these to a higher value (the C<interval> I<must> be >= C<0>) |
|
|
644 | allows libev to delay invocation of I/O and timer/periodic callbacks to |
|
|
645 | increase efficiency of loop iterations. |
|
|
646 | |
|
|
647 | The background is that sometimes your program runs just fast enough to |
|
|
648 | handle one (or very few) event(s) per loop iteration. While this makes |
|
|
649 | the program responsive, it also wastes a lot of CPU time to poll for new |
|
|
650 | events, especially with backends like C<select ()> which have a high |
|
|
651 | overhead for the actual polling but can deliver many events at once. |
|
|
652 | |
|
|
653 | By setting a higher I<io collect interval> you allow libev to spend more |
|
|
654 | time collecting I/O events, so you can handle more events per iteration, |
|
|
655 | at the cost of increasing latency. Timeouts (both C<ev_periodic> and |
|
|
656 | C<ev_timer>) will be not affected. Setting this to a non-null value will |
|
|
657 | introduce an additional C<ev_sleep ()> call into most loop iterations. |
|
|
658 | |
|
|
659 | Likewise, by setting a higher I<timeout collect interval> you allow libev |
|
|
660 | to spend more time collecting timeouts, at the expense of increased |
|
|
661 | latency (the watcher callback will be called later). C<ev_io> watchers |
|
|
662 | will not be affected. Setting this to a non-null value will not introduce |
|
|
663 | any overhead in libev. |
|
|
664 | |
|
|
665 | Many (busy) programs can usually benefit by setting the io collect |
|
|
666 | interval to a value near C<0.1> or so, which is often enough for |
|
|
667 | interactive servers (of course not for games), likewise for timeouts. It |
|
|
668 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
|
|
669 | as this approsaches the timing granularity of most systems. |
258 | |
670 | |
259 | =back |
671 | =back |
|
|
672 | |
260 | |
673 | |
261 | =head1 ANATOMY OF A WATCHER |
674 | =head1 ANATOMY OF A WATCHER |
262 | |
675 | |
263 | A watcher is a structure that you create and register to record your |
676 | A watcher is a structure that you create and register to record your |
264 | interest in some event. For instance, if you want to wait for STDIN to |
677 | interest in some event. For instance, if you want to wait for STDIN to |
… | |
… | |
297 | *) >>), and you can stop watching for events at any time by calling the |
710 | *) >>), and you can stop watching for events at any time by calling the |
298 | corresponding stop function (C<< ev_<type>_stop (loop, watcher *) >>. |
711 | corresponding stop function (C<< ev_<type>_stop (loop, watcher *) >>. |
299 | |
712 | |
300 | As long as your watcher is active (has been started but not stopped) you |
713 | As long as your watcher is active (has been started but not stopped) you |
301 | must not touch the values stored in it. Most specifically you must never |
714 | must not touch the values stored in it. Most specifically you must never |
302 | reinitialise it or call its set method. |
715 | reinitialise it or call its C<set> macro. |
303 | |
|
|
304 | You can check whether an event is active by calling the C<ev_is_active |
|
|
305 | (watcher *)> macro. To see whether an event is outstanding (but the |
|
|
306 | callback for it has not been called yet) you can use the C<ev_is_pending |
|
|
307 | (watcher *)> macro. |
|
|
308 | |
716 | |
309 | Each and every callback receives the event loop pointer as first, the |
717 | Each and every callback receives the event loop pointer as first, the |
310 | registered watcher structure as second, and a bitset of received events as |
718 | registered watcher structure as second, and a bitset of received events as |
311 | third argument. |
719 | third argument. |
312 | |
720 | |
… | |
… | |
336 | The signal specified in the C<ev_signal> watcher has been received by a thread. |
744 | The signal specified in the C<ev_signal> watcher has been received by a thread. |
337 | |
745 | |
338 | =item C<EV_CHILD> |
746 | =item C<EV_CHILD> |
339 | |
747 | |
340 | The pid specified in the C<ev_child> watcher has received a status change. |
748 | The pid specified in the C<ev_child> watcher has received a status change. |
|
|
749 | |
|
|
750 | =item C<EV_STAT> |
|
|
751 | |
|
|
752 | The path specified in the C<ev_stat> watcher changed its attributes somehow. |
341 | |
753 | |
342 | =item C<EV_IDLE> |
754 | =item C<EV_IDLE> |
343 | |
755 | |
344 | The C<ev_idle> watcher has determined that you have nothing better to do. |
756 | The C<ev_idle> watcher has determined that you have nothing better to do. |
345 | |
757 | |
… | |
… | |
353 | received events. Callbacks of both watcher types can start and stop as |
765 | received events. Callbacks of both watcher types can start and stop as |
354 | many watchers as they want, and all of them will be taken into account |
766 | many watchers as they want, and all of them will be taken into account |
355 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
767 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
356 | C<ev_loop> from blocking). |
768 | C<ev_loop> from blocking). |
357 | |
769 | |
|
|
770 | =item C<EV_EMBED> |
|
|
771 | |
|
|
772 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
|
|
773 | |
|
|
774 | =item C<EV_FORK> |
|
|
775 | |
|
|
776 | The event loop has been resumed in the child process after fork (see |
|
|
777 | C<ev_fork>). |
|
|
778 | |
|
|
779 | =item C<EV_ASYNC> |
|
|
780 | |
|
|
781 | The given async watcher has been asynchronously notified (see C<ev_async>). |
|
|
782 | |
358 | =item C<EV_ERROR> |
783 | =item C<EV_ERROR> |
359 | |
784 | |
360 | An unspecified error has occured, the watcher has been stopped. This might |
785 | An unspecified error has occured, the watcher has been stopped. This might |
361 | happen because the watcher could not be properly started because libev |
786 | happen because the watcher could not be properly started because libev |
362 | ran out of memory, a file descriptor was found to be closed or any other |
787 | ran out of memory, a file descriptor was found to be closed or any other |
… | |
… | |
368 | your callbacks is well-written it can just attempt the operation and cope |
793 | your callbacks is well-written it can just attempt the operation and cope |
369 | with the error from read() or write(). This will not work in multithreaded |
794 | with the error from read() or write(). This will not work in multithreaded |
370 | programs, though, so beware. |
795 | programs, though, so beware. |
371 | |
796 | |
372 | =back |
797 | =back |
|
|
798 | |
|
|
799 | =head2 GENERIC WATCHER FUNCTIONS |
|
|
800 | |
|
|
801 | In the following description, C<TYPE> stands for the watcher type, |
|
|
802 | e.g. C<timer> for C<ev_timer> watchers and C<io> for C<ev_io> watchers. |
|
|
803 | |
|
|
804 | =over 4 |
|
|
805 | |
|
|
806 | =item C<ev_init> (ev_TYPE *watcher, callback) |
|
|
807 | |
|
|
808 | This macro initialises the generic portion of a watcher. The contents |
|
|
809 | of the watcher object can be arbitrary (so C<malloc> will do). Only |
|
|
810 | the generic parts of the watcher are initialised, you I<need> to call |
|
|
811 | the type-specific C<ev_TYPE_set> macro afterwards to initialise the |
|
|
812 | type-specific parts. For each type there is also a C<ev_TYPE_init> macro |
|
|
813 | which rolls both calls into one. |
|
|
814 | |
|
|
815 | You can reinitialise a watcher at any time as long as it has been stopped |
|
|
816 | (or never started) and there are no pending events outstanding. |
|
|
817 | |
|
|
818 | The callback is always of type C<void (*)(ev_loop *loop, ev_TYPE *watcher, |
|
|
819 | int revents)>. |
|
|
820 | |
|
|
821 | =item C<ev_TYPE_set> (ev_TYPE *, [args]) |
|
|
822 | |
|
|
823 | This macro initialises the type-specific parts of a watcher. You need to |
|
|
824 | call C<ev_init> at least once before you call this macro, but you can |
|
|
825 | call C<ev_TYPE_set> any number of times. You must not, however, call this |
|
|
826 | macro on a watcher that is active (it can be pending, however, which is a |
|
|
827 | difference to the C<ev_init> macro). |
|
|
828 | |
|
|
829 | Although some watcher types do not have type-specific arguments |
|
|
830 | (e.g. C<ev_prepare>) you still need to call its C<set> macro. |
|
|
831 | |
|
|
832 | =item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args]) |
|
|
833 | |
|
|
834 | This convinience macro rolls both C<ev_init> and C<ev_TYPE_set> macro |
|
|
835 | calls into a single call. This is the most convinient method to initialise |
|
|
836 | a watcher. The same limitations apply, of course. |
|
|
837 | |
|
|
838 | =item C<ev_TYPE_start> (loop *, ev_TYPE *watcher) |
|
|
839 | |
|
|
840 | Starts (activates) the given watcher. Only active watchers will receive |
|
|
841 | events. If the watcher is already active nothing will happen. |
|
|
842 | |
|
|
843 | =item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher) |
|
|
844 | |
|
|
845 | Stops the given watcher again (if active) and clears the pending |
|
|
846 | status. It is possible that stopped watchers are pending (for example, |
|
|
847 | non-repeating timers are being stopped when they become pending), but |
|
|
848 | C<ev_TYPE_stop> ensures that the watcher is neither active nor pending. If |
|
|
849 | you want to free or reuse the memory used by the watcher it is therefore a |
|
|
850 | good idea to always call its C<ev_TYPE_stop> function. |
|
|
851 | |
|
|
852 | =item bool ev_is_active (ev_TYPE *watcher) |
|
|
853 | |
|
|
854 | Returns a true value iff the watcher is active (i.e. it has been started |
|
|
855 | and not yet been stopped). As long as a watcher is active you must not modify |
|
|
856 | it. |
|
|
857 | |
|
|
858 | =item bool ev_is_pending (ev_TYPE *watcher) |
|
|
859 | |
|
|
860 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
|
|
861 | events but its callback has not yet been invoked). As long as a watcher |
|
|
862 | is pending (but not active) you must not call an init function on it (but |
|
|
863 | C<ev_TYPE_set> is safe), you must not change its priority, and you must |
|
|
864 | make sure the watcher is available to libev (e.g. you cannot C<free ()> |
|
|
865 | it). |
|
|
866 | |
|
|
867 | =item callback ev_cb (ev_TYPE *watcher) |
|
|
868 | |
|
|
869 | Returns the callback currently set on the watcher. |
|
|
870 | |
|
|
871 | =item ev_cb_set (ev_TYPE *watcher, callback) |
|
|
872 | |
|
|
873 | Change the callback. You can change the callback at virtually any time |
|
|
874 | (modulo threads). |
|
|
875 | |
|
|
876 | =item ev_set_priority (ev_TYPE *watcher, priority) |
|
|
877 | |
|
|
878 | =item int ev_priority (ev_TYPE *watcher) |
|
|
879 | |
|
|
880 | Set and query the priority of the watcher. The priority is a small |
|
|
881 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
|
|
882 | (default: C<-2>). Pending watchers with higher priority will be invoked |
|
|
883 | before watchers with lower priority, but priority will not keep watchers |
|
|
884 | from being executed (except for C<ev_idle> watchers). |
|
|
885 | |
|
|
886 | This means that priorities are I<only> used for ordering callback |
|
|
887 | invocation after new events have been received. This is useful, for |
|
|
888 | example, to reduce latency after idling, or more often, to bind two |
|
|
889 | watchers on the same event and make sure one is called first. |
|
|
890 | |
|
|
891 | If you need to suppress invocation when higher priority events are pending |
|
|
892 | you need to look at C<ev_idle> watchers, which provide this functionality. |
|
|
893 | |
|
|
894 | You I<must not> change the priority of a watcher as long as it is active or |
|
|
895 | pending. |
|
|
896 | |
|
|
897 | The default priority used by watchers when no priority has been set is |
|
|
898 | always C<0>, which is supposed to not be too high and not be too low :). |
|
|
899 | |
|
|
900 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
|
|
901 | fine, as long as you do not mind that the priority value you query might |
|
|
902 | or might not have been adjusted to be within valid range. |
|
|
903 | |
|
|
904 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
|
|
905 | |
|
|
906 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
|
|
907 | C<loop> nor C<revents> need to be valid as long as the watcher callback |
|
|
908 | can deal with that fact. |
|
|
909 | |
|
|
910 | =item int ev_clear_pending (loop, ev_TYPE *watcher) |
|
|
911 | |
|
|
912 | If the watcher is pending, this function returns clears its pending status |
|
|
913 | and returns its C<revents> bitset (as if its callback was invoked). If the |
|
|
914 | watcher isn't pending it does nothing and returns C<0>. |
|
|
915 | |
|
|
916 | =back |
|
|
917 | |
373 | |
918 | |
374 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
919 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
375 | |
920 | |
376 | Each watcher has, by default, a member C<void *data> that you can change |
921 | Each watcher has, by default, a member C<void *data> that you can change |
377 | and read at any time, libev will completely ignore it. This can be used |
922 | and read at any time, libev will completely ignore it. This can be used |
… | |
… | |
395 | { |
940 | { |
396 | struct my_io *w = (struct my_io *)w_; |
941 | struct my_io *w = (struct my_io *)w_; |
397 | ... |
942 | ... |
398 | } |
943 | } |
399 | |
944 | |
400 | More interesting and less C-conformant ways of catsing your callback type |
945 | More interesting and less C-conformant ways of casting your callback type |
401 | have been omitted.... |
946 | instead have been omitted. |
|
|
947 | |
|
|
948 | Another common scenario is having some data structure with multiple |
|
|
949 | watchers: |
|
|
950 | |
|
|
951 | struct my_biggy |
|
|
952 | { |
|
|
953 | int some_data; |
|
|
954 | ev_timer t1; |
|
|
955 | ev_timer t2; |
|
|
956 | } |
|
|
957 | |
|
|
958 | In this case getting the pointer to C<my_biggy> is a bit more complicated, |
|
|
959 | you need to use C<offsetof>: |
|
|
960 | |
|
|
961 | #include <stddef.h> |
|
|
962 | |
|
|
963 | static void |
|
|
964 | t1_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
965 | { |
|
|
966 | struct my_biggy big = (struct my_biggy * |
|
|
967 | (((char *)w) - offsetof (struct my_biggy, t1)); |
|
|
968 | } |
|
|
969 | |
|
|
970 | static void |
|
|
971 | t2_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
972 | { |
|
|
973 | struct my_biggy big = (struct my_biggy * |
|
|
974 | (((char *)w) - offsetof (struct my_biggy, t2)); |
|
|
975 | } |
402 | |
976 | |
403 | |
977 | |
404 | =head1 WATCHER TYPES |
978 | =head1 WATCHER TYPES |
405 | |
979 | |
406 | This section describes each watcher in detail, but will not repeat |
980 | This section describes each watcher in detail, but will not repeat |
407 | information given in the last section. |
981 | information given in the last section. Any initialisation/set macros, |
|
|
982 | functions and members specific to the watcher type are explained. |
408 | |
983 | |
|
|
984 | Members are additionally marked with either I<[read-only]>, meaning that, |
|
|
985 | while the watcher is active, you can look at the member and expect some |
|
|
986 | sensible content, but you must not modify it (you can modify it while the |
|
|
987 | watcher is stopped to your hearts content), or I<[read-write]>, which |
|
|
988 | means you can expect it to have some sensible content while the watcher |
|
|
989 | is active, but you can also modify it. Modifying it may not do something |
|
|
990 | sensible or take immediate effect (or do anything at all), but libev will |
|
|
991 | not crash or malfunction in any way. |
|
|
992 | |
|
|
993 | |
409 | =head2 C<ev_io> - is this file descriptor readable or writable |
994 | =head2 C<ev_io> - is this file descriptor readable or writable? |
410 | |
995 | |
411 | I/O watchers check whether a file descriptor is readable or writable |
996 | I/O watchers check whether a file descriptor is readable or writable |
412 | in each iteration of the event loop (This behaviour is called |
997 | in each iteration of the event loop, or, more precisely, when reading |
413 | level-triggering because you keep receiving events as long as the |
998 | would not block the process and writing would at least be able to write |
414 | condition persists. Remember you can stop the watcher if you don't want to |
999 | some data. This behaviour is called level-triggering because you keep |
415 | act on the event and neither want to receive future events). |
1000 | receiving events as long as the condition persists. Remember you can stop |
|
|
1001 | the watcher if you don't want to act on the event and neither want to |
|
|
1002 | receive future events. |
416 | |
1003 | |
417 | In general you can register as many read and/or write event watchers oer |
1004 | In general you can register as many read and/or write event watchers per |
418 | fd as you want (as long as you don't confuse yourself). Setting all file |
1005 | fd as you want (as long as you don't confuse yourself). Setting all file |
419 | descriptors to non-blocking mode is also usually a good idea (but not |
1006 | descriptors to non-blocking mode is also usually a good idea (but not |
420 | required if you know what you are doing). |
1007 | required if you know what you are doing). |
421 | |
1008 | |
422 | You have to be careful with dup'ed file descriptors, though. Some backends |
|
|
423 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
|
|
424 | descriptors correctly if you register interest in two or more fds pointing |
|
|
425 | to the same file/socket etc. description. |
|
|
426 | |
|
|
427 | If you must do this, then force the use of a known-to-be-good backend |
1009 | If you must do this, then force the use of a known-to-be-good backend |
428 | (at the time of this writing, this includes only EVMETHOD_SELECT and |
1010 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
429 | EVMETHOD_POLL). |
1011 | C<EVBACKEND_POLL>). |
|
|
1012 | |
|
|
1013 | Another thing you have to watch out for is that it is quite easy to |
|
|
1014 | receive "spurious" readyness notifications, that is your callback might |
|
|
1015 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
|
|
1016 | because there is no data. Not only are some backends known to create a |
|
|
1017 | lot of those (for example solaris ports), it is very easy to get into |
|
|
1018 | this situation even with a relatively standard program structure. Thus |
|
|
1019 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
|
|
1020 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
|
|
1021 | |
|
|
1022 | If you cannot run the fd in non-blocking mode (for example you should not |
|
|
1023 | play around with an Xlib connection), then you have to seperately re-test |
|
|
1024 | whether a file descriptor is really ready with a known-to-be good interface |
|
|
1025 | such as poll (fortunately in our Xlib example, Xlib already does this on |
|
|
1026 | its own, so its quite safe to use). |
|
|
1027 | |
|
|
1028 | =head3 The special problem of disappearing file descriptors |
|
|
1029 | |
|
|
1030 | Some backends (e.g. kqueue, epoll) need to be told about closing a file |
|
|
1031 | descriptor (either by calling C<close> explicitly or by any other means, |
|
|
1032 | such as C<dup>). The reason is that you register interest in some file |
|
|
1033 | descriptor, but when it goes away, the operating system will silently drop |
|
|
1034 | this interest. If another file descriptor with the same number then is |
|
|
1035 | registered with libev, there is no efficient way to see that this is, in |
|
|
1036 | fact, a different file descriptor. |
|
|
1037 | |
|
|
1038 | To avoid having to explicitly tell libev about such cases, libev follows |
|
|
1039 | the following policy: Each time C<ev_io_set> is being called, libev |
|
|
1040 | will assume that this is potentially a new file descriptor, otherwise |
|
|
1041 | it is assumed that the file descriptor stays the same. That means that |
|
|
1042 | you I<have> to call C<ev_io_set> (or C<ev_io_init>) when you change the |
|
|
1043 | descriptor even if the file descriptor number itself did not change. |
|
|
1044 | |
|
|
1045 | This is how one would do it normally anyway, the important point is that |
|
|
1046 | the libev application should not optimise around libev but should leave |
|
|
1047 | optimisations to libev. |
|
|
1048 | |
|
|
1049 | =head3 The special problem of dup'ed file descriptors |
|
|
1050 | |
|
|
1051 | Some backends (e.g. epoll), cannot register events for file descriptors, |
|
|
1052 | but only events for the underlying file descriptions. That means when you |
|
|
1053 | have C<dup ()>'ed file descriptors or weirder constellations, and register |
|
|
1054 | events for them, only one file descriptor might actually receive events. |
|
|
1055 | |
|
|
1056 | There is no workaround possible except not registering events |
|
|
1057 | for potentially C<dup ()>'ed file descriptors, or to resort to |
|
|
1058 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
|
|
1059 | |
|
|
1060 | =head3 The special problem of fork |
|
|
1061 | |
|
|
1062 | Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit |
|
|
1063 | useless behaviour. Libev fully supports fork, but needs to be told about |
|
|
1064 | it in the child. |
|
|
1065 | |
|
|
1066 | To support fork in your programs, you either have to call |
|
|
1067 | C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child, |
|
|
1068 | enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or |
|
|
1069 | C<EVBACKEND_POLL>. |
|
|
1070 | |
|
|
1071 | |
|
|
1072 | =head3 Watcher-Specific Functions |
430 | |
1073 | |
431 | =over 4 |
1074 | =over 4 |
432 | |
1075 | |
433 | =item ev_io_init (ev_io *, callback, int fd, int events) |
1076 | =item ev_io_init (ev_io *, callback, int fd, int events) |
434 | |
1077 | |
435 | =item ev_io_set (ev_io *, int fd, int events) |
1078 | =item ev_io_set (ev_io *, int fd, int events) |
436 | |
1079 | |
437 | Configures an C<ev_io> watcher. The fd is the file descriptor to rceeive |
1080 | Configures an C<ev_io> watcher. The C<fd> is the file descriptor to |
438 | events for and events is either C<EV_READ>, C<EV_WRITE> or C<EV_READ | |
1081 | rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or |
439 | EV_WRITE> to receive the given events. |
1082 | C<EV_READ | EV_WRITE> to receive the given events. |
|
|
1083 | |
|
|
1084 | =item int fd [read-only] |
|
|
1085 | |
|
|
1086 | The file descriptor being watched. |
|
|
1087 | |
|
|
1088 | =item int events [read-only] |
|
|
1089 | |
|
|
1090 | The events being watched. |
440 | |
1091 | |
441 | =back |
1092 | =back |
442 | |
1093 | |
|
|
1094 | =head3 Examples |
|
|
1095 | |
|
|
1096 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
|
|
1097 | readable, but only once. Since it is likely line-buffered, you could |
|
|
1098 | attempt to read a whole line in the callback. |
|
|
1099 | |
|
|
1100 | static void |
|
|
1101 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
|
|
1102 | { |
|
|
1103 | ev_io_stop (loop, w); |
|
|
1104 | .. read from stdin here (or from w->fd) and haqndle any I/O errors |
|
|
1105 | } |
|
|
1106 | |
|
|
1107 | ... |
|
|
1108 | struct ev_loop *loop = ev_default_init (0); |
|
|
1109 | struct ev_io stdin_readable; |
|
|
1110 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
|
|
1111 | ev_io_start (loop, &stdin_readable); |
|
|
1112 | ev_loop (loop, 0); |
|
|
1113 | |
|
|
1114 | |
443 | =head2 C<ev_timer> - relative and optionally recurring timeouts |
1115 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
444 | |
1116 | |
445 | Timer watchers are simple relative timers that generate an event after a |
1117 | Timer watchers are simple relative timers that generate an event after a |
446 | given time, and optionally repeating in regular intervals after that. |
1118 | given time, and optionally repeating in regular intervals after that. |
447 | |
1119 | |
448 | The timers are based on real time, that is, if you register an event that |
1120 | The timers are based on real time, that is, if you register an event that |
449 | times out after an hour and youreset your system clock to last years |
1121 | times out after an hour and you reset your system clock to last years |
450 | time, it will still time out after (roughly) and hour. "Roughly" because |
1122 | time, it will still time out after (roughly) and hour. "Roughly" because |
451 | detecting time jumps is hard, and soem inaccuracies are unavoidable (the |
1123 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
452 | monotonic clock option helps a lot here). |
1124 | monotonic clock option helps a lot here). |
453 | |
1125 | |
454 | The relative timeouts are calculated relative to the C<ev_now ()> |
1126 | The relative timeouts are calculated relative to the C<ev_now ()> |
455 | time. This is usually the right thing as this timestamp refers to the time |
1127 | time. This is usually the right thing as this timestamp refers to the time |
456 | of the event triggering whatever timeout you are modifying/starting. If |
1128 | of the event triggering whatever timeout you are modifying/starting. If |
457 | you suspect event processing to be delayed and you *need* to base the timeout |
1129 | you suspect event processing to be delayed and you I<need> to base the timeout |
458 | ion the current time, use something like this to adjust for this: |
1130 | on the current time, use something like this to adjust for this: |
459 | |
1131 | |
460 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
1132 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
|
|
1133 | |
|
|
1134 | The callback is guarenteed to be invoked only when its timeout has passed, |
|
|
1135 | but if multiple timers become ready during the same loop iteration then |
|
|
1136 | order of execution is undefined. |
|
|
1137 | |
|
|
1138 | =head3 Watcher-Specific Functions and Data Members |
461 | |
1139 | |
462 | =over 4 |
1140 | =over 4 |
463 | |
1141 | |
464 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
1142 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
465 | |
1143 | |
… | |
… | |
471 | later, again, and again, until stopped manually. |
1149 | later, again, and again, until stopped manually. |
472 | |
1150 | |
473 | The timer itself will do a best-effort at avoiding drift, that is, if you |
1151 | The timer itself will do a best-effort at avoiding drift, that is, if you |
474 | configure a timer to trigger every 10 seconds, then it will trigger at |
1152 | configure a timer to trigger every 10 seconds, then it will trigger at |
475 | exactly 10 second intervals. If, however, your program cannot keep up with |
1153 | exactly 10 second intervals. If, however, your program cannot keep up with |
476 | the timer (ecause it takes longer than those 10 seconds to do stuff) the |
1154 | the timer (because it takes longer than those 10 seconds to do stuff) the |
477 | timer will not fire more than once per event loop iteration. |
1155 | timer will not fire more than once per event loop iteration. |
478 | |
1156 | |
479 | =item ev_timer_again (loop) |
1157 | =item ev_timer_again (loop) |
480 | |
1158 | |
481 | This will act as if the timer timed out and restart it again if it is |
1159 | This will act as if the timer timed out and restart it again if it is |
482 | repeating. The exact semantics are: |
1160 | repeating. The exact semantics are: |
483 | |
1161 | |
|
|
1162 | If the timer is pending, its pending status is cleared. |
|
|
1163 | |
484 | If the timer is started but nonrepeating, stop it. |
1164 | If the timer is started but nonrepeating, stop it (as if it timed out). |
485 | |
1165 | |
486 | If the timer is repeating, either start it if necessary (with the repeat |
1166 | If the timer is repeating, either start it if necessary (with the |
487 | value), or reset the running timer to the repeat value. |
1167 | C<repeat> value), or reset the running timer to the C<repeat> value. |
488 | |
1168 | |
489 | This sounds a bit complicated, but here is a useful and typical |
1169 | This sounds a bit complicated, but here is a useful and typical |
490 | example: Imagine you have a tcp connection and you want a so-called idle |
1170 | example: Imagine you have a tcp connection and you want a so-called idle |
491 | timeout, that is, you want to be called when there have been, say, 60 |
1171 | timeout, that is, you want to be called when there have been, say, 60 |
492 | seconds of inactivity on the socket. The easiest way to do this is to |
1172 | seconds of inactivity on the socket. The easiest way to do this is to |
493 | configure an C<ev_timer> with after=repeat=60 and calling ev_timer_again each |
1173 | configure an C<ev_timer> with a C<repeat> value of C<60> and then call |
494 | time you successfully read or write some data. If you go into an idle |
1174 | C<ev_timer_again> each time you successfully read or write some data. If |
495 | state where you do not expect data to travel on the socket, you can stop |
1175 | you go into an idle state where you do not expect data to travel on the |
496 | the timer, and again will automatically restart it if need be. |
1176 | socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will |
|
|
1177 | automatically restart it if need be. |
|
|
1178 | |
|
|
1179 | That means you can ignore the C<after> value and C<ev_timer_start> |
|
|
1180 | altogether and only ever use the C<repeat> value and C<ev_timer_again>: |
|
|
1181 | |
|
|
1182 | ev_timer_init (timer, callback, 0., 5.); |
|
|
1183 | ev_timer_again (loop, timer); |
|
|
1184 | ... |
|
|
1185 | timer->again = 17.; |
|
|
1186 | ev_timer_again (loop, timer); |
|
|
1187 | ... |
|
|
1188 | timer->again = 10.; |
|
|
1189 | ev_timer_again (loop, timer); |
|
|
1190 | |
|
|
1191 | This is more slightly efficient then stopping/starting the timer each time |
|
|
1192 | you want to modify its timeout value. |
|
|
1193 | |
|
|
1194 | =item ev_tstamp repeat [read-write] |
|
|
1195 | |
|
|
1196 | The current C<repeat> value. Will be used each time the watcher times out |
|
|
1197 | or C<ev_timer_again> is called and determines the next timeout (if any), |
|
|
1198 | which is also when any modifications are taken into account. |
497 | |
1199 | |
498 | =back |
1200 | =back |
499 | |
1201 | |
|
|
1202 | =head3 Examples |
|
|
1203 | |
|
|
1204 | Example: Create a timer that fires after 60 seconds. |
|
|
1205 | |
|
|
1206 | static void |
|
|
1207 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
|
|
1208 | { |
|
|
1209 | .. one minute over, w is actually stopped right here |
|
|
1210 | } |
|
|
1211 | |
|
|
1212 | struct ev_timer mytimer; |
|
|
1213 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
|
|
1214 | ev_timer_start (loop, &mytimer); |
|
|
1215 | |
|
|
1216 | Example: Create a timeout timer that times out after 10 seconds of |
|
|
1217 | inactivity. |
|
|
1218 | |
|
|
1219 | static void |
|
|
1220 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
|
|
1221 | { |
|
|
1222 | .. ten seconds without any activity |
|
|
1223 | } |
|
|
1224 | |
|
|
1225 | struct ev_timer mytimer; |
|
|
1226 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
|
|
1227 | ev_timer_again (&mytimer); /* start timer */ |
|
|
1228 | ev_loop (loop, 0); |
|
|
1229 | |
|
|
1230 | // and in some piece of code that gets executed on any "activity": |
|
|
1231 | // reset the timeout to start ticking again at 10 seconds |
|
|
1232 | ev_timer_again (&mytimer); |
|
|
1233 | |
|
|
1234 | |
500 | =head2 C<ev_periodic> - to cron or not to cron |
1235 | =head2 C<ev_periodic> - to cron or not to cron? |
501 | |
1236 | |
502 | Periodic watchers are also timers of a kind, but they are very versatile |
1237 | Periodic watchers are also timers of a kind, but they are very versatile |
503 | (and unfortunately a bit complex). |
1238 | (and unfortunately a bit complex). |
504 | |
1239 | |
505 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
1240 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
506 | but on wallclock time (absolute time). You can tell a periodic watcher |
1241 | but on wallclock time (absolute time). You can tell a periodic watcher |
507 | to trigger "at" some specific point in time. For example, if you tell a |
1242 | to trigger "at" some specific point in time. For example, if you tell a |
508 | periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now () |
1243 | periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now () |
509 | + 10.>) and then reset your system clock to the last year, then it will |
1244 | + 10.>) and then reset your system clock to the last year, then it will |
510 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
1245 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
511 | roughly 10 seconds later and of course not if you reset your system time |
1246 | roughly 10 seconds later). |
512 | again). |
|
|
513 | |
1247 | |
514 | They can also be used to implement vastly more complex timers, such as |
1248 | They can also be used to implement vastly more complex timers, such as |
515 | triggering an event on eahc midnight, local time. |
1249 | triggering an event on each midnight, local time or other, complicated, |
|
|
1250 | rules. |
|
|
1251 | |
|
|
1252 | As with timers, the callback is guarenteed to be invoked only when the |
|
|
1253 | time (C<at>) has been passed, but if multiple periodic timers become ready |
|
|
1254 | during the same loop iteration then order of execution is undefined. |
|
|
1255 | |
|
|
1256 | =head3 Watcher-Specific Functions and Data Members |
516 | |
1257 | |
517 | =over 4 |
1258 | =over 4 |
518 | |
1259 | |
519 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
1260 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
520 | |
1261 | |
521 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
1262 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
522 | |
1263 | |
523 | Lots of arguments, lets sort it out... There are basically three modes of |
1264 | Lots of arguments, lets sort it out... There are basically three modes of |
524 | operation, and we will explain them from simplest to complex: |
1265 | operation, and we will explain them from simplest to complex: |
525 | |
1266 | |
526 | |
|
|
527 | =over 4 |
1267 | =over 4 |
528 | |
1268 | |
529 | =item * absolute timer (interval = reschedule_cb = 0) |
1269 | =item * absolute timer (at = time, interval = reschedule_cb = 0) |
530 | |
1270 | |
531 | In this configuration the watcher triggers an event at the wallclock time |
1271 | In this configuration the watcher triggers an event at the wallclock time |
532 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
1272 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
533 | that is, if it is to be run at January 1st 2011 then it will run when the |
1273 | that is, if it is to be run at January 1st 2011 then it will run when the |
534 | system time reaches or surpasses this time. |
1274 | system time reaches or surpasses this time. |
535 | |
1275 | |
536 | =item * non-repeating interval timer (interval > 0, reschedule_cb = 0) |
1276 | =item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
537 | |
1277 | |
538 | In this mode the watcher will always be scheduled to time out at the next |
1278 | In this mode the watcher will always be scheduled to time out at the next |
539 | C<at + N * interval> time (for some integer N) and then repeat, regardless |
1279 | C<at + N * interval> time (for some integer N, which can also be negative) |
540 | of any time jumps. |
1280 | and then repeat, regardless of any time jumps. |
541 | |
1281 | |
542 | This can be used to create timers that do not drift with respect to system |
1282 | This can be used to create timers that do not drift with respect to system |
543 | time: |
1283 | time: |
544 | |
1284 | |
545 | ev_periodic_set (&periodic, 0., 3600., 0); |
1285 | ev_periodic_set (&periodic, 0., 3600., 0); |
… | |
… | |
551 | |
1291 | |
552 | Another way to think about it (for the mathematically inclined) is that |
1292 | Another way to think about it (for the mathematically inclined) is that |
553 | C<ev_periodic> will try to run the callback in this mode at the next possible |
1293 | C<ev_periodic> will try to run the callback in this mode at the next possible |
554 | time where C<time = at (mod interval)>, regardless of any time jumps. |
1294 | time where C<time = at (mod interval)>, regardless of any time jumps. |
555 | |
1295 | |
|
|
1296 | For numerical stability it is preferable that the C<at> value is near |
|
|
1297 | C<ev_now ()> (the current time), but there is no range requirement for |
|
|
1298 | this value. |
|
|
1299 | |
556 | =item * manual reschedule mode (reschedule_cb = callback) |
1300 | =item * manual reschedule mode (at and interval ignored, reschedule_cb = callback) |
557 | |
1301 | |
558 | In this mode the values for C<interval> and C<at> are both being |
1302 | In this mode the values for C<interval> and C<at> are both being |
559 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1303 | ignored. Instead, each time the periodic watcher gets scheduled, the |
560 | reschedule callback will be called with the watcher as first, and the |
1304 | reschedule callback will be called with the watcher as first, and the |
561 | current time as second argument. |
1305 | current time as second argument. |
562 | |
1306 | |
563 | NOTE: I<This callback MUST NOT stop or destroy the periodic or any other |
1307 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
564 | periodic watcher, ever, or make any event loop modifications>. If you need |
1308 | ever, or make any event loop modifications>. If you need to stop it, |
565 | to stop it, return C<now + 1e30> (or so, fudge fudge) and stop it afterwards. |
1309 | return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by |
566 | |
1310 | starting an C<ev_prepare> watcher, which is legal). |
567 | Also, I<< this callback must always return a time that is later than the |
|
|
568 | passed C<now> value >>. Not even C<now> itself will be ok. |
|
|
569 | |
1311 | |
570 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1312 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
571 | ev_tstamp now)>, e.g.: |
1313 | ev_tstamp now)>, e.g.: |
572 | |
1314 | |
573 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
1315 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
… | |
… | |
578 | It must return the next time to trigger, based on the passed time value |
1320 | It must return the next time to trigger, based on the passed time value |
579 | (that is, the lowest time value larger than to the second argument). It |
1321 | (that is, the lowest time value larger than to the second argument). It |
580 | will usually be called just before the callback will be triggered, but |
1322 | will usually be called just before the callback will be triggered, but |
581 | might be called at other times, too. |
1323 | might be called at other times, too. |
582 | |
1324 | |
|
|
1325 | NOTE: I<< This callback must always return a time that is later than the |
|
|
1326 | passed C<now> value >>. Not even C<now> itself will do, it I<must> be larger. |
|
|
1327 | |
583 | This can be used to create very complex timers, such as a timer that |
1328 | This can be used to create very complex timers, such as a timer that |
584 | triggers on each midnight, local time. To do this, you would calculate the |
1329 | triggers on each midnight, local time. To do this, you would calculate the |
585 | next midnight after C<now> and return the timestamp value for this. How you do this |
1330 | next midnight after C<now> and return the timestamp value for this. How |
586 | is, again, up to you (but it is not trivial). |
1331 | you do this is, again, up to you (but it is not trivial, which is the main |
|
|
1332 | reason I omitted it as an example). |
587 | |
1333 | |
588 | =back |
1334 | =back |
589 | |
1335 | |
590 | =item ev_periodic_again (loop, ev_periodic *) |
1336 | =item ev_periodic_again (loop, ev_periodic *) |
591 | |
1337 | |
592 | Simply stops and restarts the periodic watcher again. This is only useful |
1338 | Simply stops and restarts the periodic watcher again. This is only useful |
593 | when you changed some parameters or the reschedule callback would return |
1339 | when you changed some parameters or the reschedule callback would return |
594 | a different time than the last time it was called (e.g. in a crond like |
1340 | a different time than the last time it was called (e.g. in a crond like |
595 | program when the crontabs have changed). |
1341 | program when the crontabs have changed). |
596 | |
1342 | |
|
|
1343 | =item ev_tstamp offset [read-write] |
|
|
1344 | |
|
|
1345 | When repeating, this contains the offset value, otherwise this is the |
|
|
1346 | absolute point in time (the C<at> value passed to C<ev_periodic_set>). |
|
|
1347 | |
|
|
1348 | Can be modified any time, but changes only take effect when the periodic |
|
|
1349 | timer fires or C<ev_periodic_again> is being called. |
|
|
1350 | |
|
|
1351 | =item ev_tstamp interval [read-write] |
|
|
1352 | |
|
|
1353 | The current interval value. Can be modified any time, but changes only |
|
|
1354 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
|
|
1355 | called. |
|
|
1356 | |
|
|
1357 | =item ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write] |
|
|
1358 | |
|
|
1359 | The current reschedule callback, or C<0>, if this functionality is |
|
|
1360 | switched off. Can be changed any time, but changes only take effect when |
|
|
1361 | the periodic timer fires or C<ev_periodic_again> is being called. |
|
|
1362 | |
|
|
1363 | =item ev_tstamp at [read-only] |
|
|
1364 | |
|
|
1365 | When active, contains the absolute time that the watcher is supposed to |
|
|
1366 | trigger next. |
|
|
1367 | |
597 | =back |
1368 | =back |
598 | |
1369 | |
|
|
1370 | =head3 Examples |
|
|
1371 | |
|
|
1372 | Example: Call a callback every hour, or, more precisely, whenever the |
|
|
1373 | system clock is divisible by 3600. The callback invocation times have |
|
|
1374 | potentially a lot of jittering, but good long-term stability. |
|
|
1375 | |
|
|
1376 | static void |
|
|
1377 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
|
|
1378 | { |
|
|
1379 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
|
|
1380 | } |
|
|
1381 | |
|
|
1382 | struct ev_periodic hourly_tick; |
|
|
1383 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
|
|
1384 | ev_periodic_start (loop, &hourly_tick); |
|
|
1385 | |
|
|
1386 | Example: The same as above, but use a reschedule callback to do it: |
|
|
1387 | |
|
|
1388 | #include <math.h> |
|
|
1389 | |
|
|
1390 | static ev_tstamp |
|
|
1391 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
|
|
1392 | { |
|
|
1393 | return fmod (now, 3600.) + 3600.; |
|
|
1394 | } |
|
|
1395 | |
|
|
1396 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
|
|
1397 | |
|
|
1398 | Example: Call a callback every hour, starting now: |
|
|
1399 | |
|
|
1400 | struct ev_periodic hourly_tick; |
|
|
1401 | ev_periodic_init (&hourly_tick, clock_cb, |
|
|
1402 | fmod (ev_now (loop), 3600.), 3600., 0); |
|
|
1403 | ev_periodic_start (loop, &hourly_tick); |
|
|
1404 | |
|
|
1405 | |
599 | =head2 C<ev_signal> - signal me when a signal gets signalled |
1406 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
600 | |
1407 | |
601 | Signal watchers will trigger an event when the process receives a specific |
1408 | Signal watchers will trigger an event when the process receives a specific |
602 | signal one or more times. Even though signals are very asynchronous, libev |
1409 | signal one or more times. Even though signals are very asynchronous, libev |
603 | will try it's best to deliver signals synchronously, i.e. as part of the |
1410 | will try it's best to deliver signals synchronously, i.e. as part of the |
604 | normal event processing, like any other event. |
1411 | normal event processing, like any other event. |
… | |
… | |
608 | with the kernel (thus it coexists with your own signal handlers as long |
1415 | with the kernel (thus it coexists with your own signal handlers as long |
609 | as you don't register any with libev). Similarly, when the last signal |
1416 | as you don't register any with libev). Similarly, when the last signal |
610 | watcher for a signal is stopped libev will reset the signal handler to |
1417 | watcher for a signal is stopped libev will reset the signal handler to |
611 | SIG_DFL (regardless of what it was set to before). |
1418 | SIG_DFL (regardless of what it was set to before). |
612 | |
1419 | |
|
|
1420 | =head3 Watcher-Specific Functions and Data Members |
|
|
1421 | |
613 | =over 4 |
1422 | =over 4 |
614 | |
1423 | |
615 | =item ev_signal_init (ev_signal *, callback, int signum) |
1424 | =item ev_signal_init (ev_signal *, callback, int signum) |
616 | |
1425 | |
617 | =item ev_signal_set (ev_signal *, int signum) |
1426 | =item ev_signal_set (ev_signal *, int signum) |
618 | |
1427 | |
619 | Configures the watcher to trigger on the given signal number (usually one |
1428 | Configures the watcher to trigger on the given signal number (usually one |
620 | of the C<SIGxxx> constants). |
1429 | of the C<SIGxxx> constants). |
621 | |
1430 | |
|
|
1431 | =item int signum [read-only] |
|
|
1432 | |
|
|
1433 | The signal the watcher watches out for. |
|
|
1434 | |
622 | =back |
1435 | =back |
623 | |
1436 | |
|
|
1437 | |
624 | =head2 C<ev_child> - wait for pid status changes |
1438 | =head2 C<ev_child> - watch out for process status changes |
625 | |
1439 | |
626 | Child watchers trigger when your process receives a SIGCHLD in response to |
1440 | Child watchers trigger when your process receives a SIGCHLD in response to |
627 | some child status changes (most typically when a child of yours dies). |
1441 | some child status changes (most typically when a child of yours dies). |
628 | |
1442 | |
|
|
1443 | =head3 Watcher-Specific Functions and Data Members |
|
|
1444 | |
629 | =over 4 |
1445 | =over 4 |
630 | |
1446 | |
631 | =item ev_child_init (ev_child *, callback, int pid) |
1447 | =item ev_child_init (ev_child *, callback, int pid, int trace) |
632 | |
1448 | |
633 | =item ev_child_set (ev_child *, int pid) |
1449 | =item ev_child_set (ev_child *, int pid, int trace) |
634 | |
1450 | |
635 | Configures the watcher to wait for status changes of process C<pid> (or |
1451 | Configures the watcher to wait for status changes of process C<pid> (or |
636 | I<any> process if C<pid> is specified as C<0>). The callback can look |
1452 | I<any> process if C<pid> is specified as C<0>). The callback can look |
637 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
1453 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
638 | the status word (use the macros from C<sys/wait.h> and see your systems |
1454 | the status word (use the macros from C<sys/wait.h> and see your systems |
639 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
1455 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
640 | process causing the status change. |
1456 | process causing the status change. C<trace> must be either C<0> (only |
|
|
1457 | activate the watcher when the process terminates) or C<1> (additionally |
|
|
1458 | activate the watcher when the process is stopped or continued). |
|
|
1459 | |
|
|
1460 | =item int pid [read-only] |
|
|
1461 | |
|
|
1462 | The process id this watcher watches out for, or C<0>, meaning any process id. |
|
|
1463 | |
|
|
1464 | =item int rpid [read-write] |
|
|
1465 | |
|
|
1466 | The process id that detected a status change. |
|
|
1467 | |
|
|
1468 | =item int rstatus [read-write] |
|
|
1469 | |
|
|
1470 | The process exit/trace status caused by C<rpid> (see your systems |
|
|
1471 | C<waitpid> and C<sys/wait.h> documentation for details). |
641 | |
1472 | |
642 | =back |
1473 | =back |
643 | |
1474 | |
|
|
1475 | =head3 Examples |
|
|
1476 | |
|
|
1477 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
|
|
1478 | |
|
|
1479 | static void |
|
|
1480 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
|
|
1481 | { |
|
|
1482 | ev_unloop (loop, EVUNLOOP_ALL); |
|
|
1483 | } |
|
|
1484 | |
|
|
1485 | struct ev_signal signal_watcher; |
|
|
1486 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
|
|
1487 | ev_signal_start (loop, &sigint_cb); |
|
|
1488 | |
|
|
1489 | |
|
|
1490 | =head2 C<ev_stat> - did the file attributes just change? |
|
|
1491 | |
|
|
1492 | This watches a filesystem path for attribute changes. That is, it calls |
|
|
1493 | C<stat> regularly (or when the OS says it changed) and sees if it changed |
|
|
1494 | compared to the last time, invoking the callback if it did. |
|
|
1495 | |
|
|
1496 | The path does not need to exist: changing from "path exists" to "path does |
|
|
1497 | not exist" is a status change like any other. The condition "path does |
|
|
1498 | not exist" is signified by the C<st_nlink> field being zero (which is |
|
|
1499 | otherwise always forced to be at least one) and all the other fields of |
|
|
1500 | the stat buffer having unspecified contents. |
|
|
1501 | |
|
|
1502 | The path I<should> be absolute and I<must not> end in a slash. If it is |
|
|
1503 | relative and your working directory changes, the behaviour is undefined. |
|
|
1504 | |
|
|
1505 | Since there is no standard to do this, the portable implementation simply |
|
|
1506 | calls C<stat (2)> regularly on the path to see if it changed somehow. You |
|
|
1507 | can specify a recommended polling interval for this case. If you specify |
|
|
1508 | a polling interval of C<0> (highly recommended!) then a I<suitable, |
|
|
1509 | unspecified default> value will be used (which you can expect to be around |
|
|
1510 | five seconds, although this might change dynamically). Libev will also |
|
|
1511 | impose a minimum interval which is currently around C<0.1>, but thats |
|
|
1512 | usually overkill. |
|
|
1513 | |
|
|
1514 | This watcher type is not meant for massive numbers of stat watchers, |
|
|
1515 | as even with OS-supported change notifications, this can be |
|
|
1516 | resource-intensive. |
|
|
1517 | |
|
|
1518 | At the time of this writing, only the Linux inotify interface is |
|
|
1519 | implemented (implementing kqueue support is left as an exercise for the |
|
|
1520 | reader). Inotify will be used to give hints only and should not change the |
|
|
1521 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
|
|
1522 | to fall back to regular polling again even with inotify, but changes are |
|
|
1523 | usually detected immediately, and if the file exists there will be no |
|
|
1524 | polling. |
|
|
1525 | |
|
|
1526 | =head3 Inotify |
|
|
1527 | |
|
|
1528 | When C<inotify (7)> support has been compiled into libev (generally only |
|
|
1529 | available on Linux) and present at runtime, it will be used to speed up |
|
|
1530 | change detection where possible. The inotify descriptor will be created lazily |
|
|
1531 | when the first C<ev_stat> watcher is being started. |
|
|
1532 | |
|
|
1533 | Inotify presense does not change the semantics of C<ev_stat> watchers |
|
|
1534 | except that changes might be detected earlier, and in some cases, to avoid |
|
|
1535 | making regular C<stat> calls. Even in the presense of inotify support |
|
|
1536 | there are many cases where libev has to resort to regular C<stat> polling. |
|
|
1537 | |
|
|
1538 | (There is no support for kqueue, as apparently it cannot be used to |
|
|
1539 | implement this functionality, due to the requirement of having a file |
|
|
1540 | descriptor open on the object at all times). |
|
|
1541 | |
|
|
1542 | =head3 The special problem of stat time resolution |
|
|
1543 | |
|
|
1544 | The C<stat ()> syscall only supports full-second resolution portably, and |
|
|
1545 | even on systems where the resolution is higher, many filesystems still |
|
|
1546 | only support whole seconds. |
|
|
1547 | |
|
|
1548 | That means that, if the time is the only thing that changes, you might |
|
|
1549 | miss updates: on the first update, C<ev_stat> detects a change and calls |
|
|
1550 | your callback, which does something. When there is another update within |
|
|
1551 | the same second, C<ev_stat> will be unable to detect it. |
|
|
1552 | |
|
|
1553 | The solution to this is to delay acting on a change for a second (or till |
|
|
1554 | the next second boundary), using a roughly one-second delay C<ev_timer> |
|
|
1555 | (C<ev_timer_set (w, 0., 1.01); ev_timer_again (loop, w)>). The C<.01> |
|
|
1556 | is added to work around small timing inconsistencies of some operating |
|
|
1557 | systems. |
|
|
1558 | |
|
|
1559 | =head3 Watcher-Specific Functions and Data Members |
|
|
1560 | |
|
|
1561 | =over 4 |
|
|
1562 | |
|
|
1563 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
|
|
1564 | |
|
|
1565 | =item ev_stat_set (ev_stat *, const char *path, ev_tstamp interval) |
|
|
1566 | |
|
|
1567 | Configures the watcher to wait for status changes of the given |
|
|
1568 | C<path>. The C<interval> is a hint on how quickly a change is expected to |
|
|
1569 | be detected and should normally be specified as C<0> to let libev choose |
|
|
1570 | a suitable value. The memory pointed to by C<path> must point to the same |
|
|
1571 | path for as long as the watcher is active. |
|
|
1572 | |
|
|
1573 | The callback will be receive C<EV_STAT> when a change was detected, |
|
|
1574 | relative to the attributes at the time the watcher was started (or the |
|
|
1575 | last change was detected). |
|
|
1576 | |
|
|
1577 | =item ev_stat_stat (ev_stat *) |
|
|
1578 | |
|
|
1579 | Updates the stat buffer immediately with new values. If you change the |
|
|
1580 | watched path in your callback, you could call this fucntion to avoid |
|
|
1581 | detecting this change (while introducing a race condition). Can also be |
|
|
1582 | useful simply to find out the new values. |
|
|
1583 | |
|
|
1584 | =item ev_statdata attr [read-only] |
|
|
1585 | |
|
|
1586 | The most-recently detected attributes of the file. Although the type is of |
|
|
1587 | C<ev_statdata>, this is usually the (or one of the) C<struct stat> types |
|
|
1588 | suitable for your system. If the C<st_nlink> member is C<0>, then there |
|
|
1589 | was some error while C<stat>ing the file. |
|
|
1590 | |
|
|
1591 | =item ev_statdata prev [read-only] |
|
|
1592 | |
|
|
1593 | The previous attributes of the file. The callback gets invoked whenever |
|
|
1594 | C<prev> != C<attr>. |
|
|
1595 | |
|
|
1596 | =item ev_tstamp interval [read-only] |
|
|
1597 | |
|
|
1598 | The specified interval. |
|
|
1599 | |
|
|
1600 | =item const char *path [read-only] |
|
|
1601 | |
|
|
1602 | The filesystem path that is being watched. |
|
|
1603 | |
|
|
1604 | =back |
|
|
1605 | |
|
|
1606 | =head3 Examples |
|
|
1607 | |
|
|
1608 | Example: Watch C</etc/passwd> for attribute changes. |
|
|
1609 | |
|
|
1610 | static void |
|
|
1611 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
|
|
1612 | { |
|
|
1613 | /* /etc/passwd changed in some way */ |
|
|
1614 | if (w->attr.st_nlink) |
|
|
1615 | { |
|
|
1616 | printf ("passwd current size %ld\n", (long)w->attr.st_size); |
|
|
1617 | printf ("passwd current atime %ld\n", (long)w->attr.st_mtime); |
|
|
1618 | printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime); |
|
|
1619 | } |
|
|
1620 | else |
|
|
1621 | /* you shalt not abuse printf for puts */ |
|
|
1622 | puts ("wow, /etc/passwd is not there, expect problems. " |
|
|
1623 | "if this is windows, they already arrived\n"); |
|
|
1624 | } |
|
|
1625 | |
|
|
1626 | ... |
|
|
1627 | ev_stat passwd; |
|
|
1628 | |
|
|
1629 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.); |
|
|
1630 | ev_stat_start (loop, &passwd); |
|
|
1631 | |
|
|
1632 | Example: Like above, but additionally use a one-second delay so we do not |
|
|
1633 | miss updates (however, frequent updates will delay processing, too, so |
|
|
1634 | one might do the work both on C<ev_stat> callback invocation I<and> on |
|
|
1635 | C<ev_timer> callback invocation). |
|
|
1636 | |
|
|
1637 | static ev_stat passwd; |
|
|
1638 | static ev_timer timer; |
|
|
1639 | |
|
|
1640 | static void |
|
|
1641 | timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1642 | { |
|
|
1643 | ev_timer_stop (EV_A_ w); |
|
|
1644 | |
|
|
1645 | /* now it's one second after the most recent passwd change */ |
|
|
1646 | } |
|
|
1647 | |
|
|
1648 | static void |
|
|
1649 | stat_cb (EV_P_ ev_stat *w, int revents) |
|
|
1650 | { |
|
|
1651 | /* reset the one-second timer */ |
|
|
1652 | ev_timer_again (EV_A_ &timer); |
|
|
1653 | } |
|
|
1654 | |
|
|
1655 | ... |
|
|
1656 | ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); |
|
|
1657 | ev_stat_start (loop, &passwd); |
|
|
1658 | ev_timer_init (&timer, timer_cb, 0., 1.01); |
|
|
1659 | |
|
|
1660 | |
644 | =head2 C<ev_idle> - when you've got nothing better to do |
1661 | =head2 C<ev_idle> - when you've got nothing better to do... |
645 | |
1662 | |
646 | Idle watchers trigger events when there are no other events are pending |
1663 | Idle watchers trigger events when no other events of the same or higher |
647 | (prepare, check and other idle watchers do not count). That is, as long |
1664 | priority are pending (prepare, check and other idle watchers do not |
648 | as your process is busy handling sockets or timeouts (or even signals, |
1665 | count). |
649 | imagine) it will not be triggered. But when your process is idle all idle |
1666 | |
650 | watchers are being called again and again, once per event loop iteration - |
1667 | That is, as long as your process is busy handling sockets or timeouts |
|
|
1668 | (or even signals, imagine) of the same or higher priority it will not be |
|
|
1669 | triggered. But when your process is idle (or only lower-priority watchers |
|
|
1670 | are pending), the idle watchers are being called once per event loop |
651 | until stopped, that is, or your process receives more events and becomes |
1671 | iteration - until stopped, that is, or your process receives more events |
652 | busy. |
1672 | and becomes busy again with higher priority stuff. |
653 | |
1673 | |
654 | The most noteworthy effect is that as long as any idle watchers are |
1674 | The most noteworthy effect is that as long as any idle watchers are |
655 | active, the process will not block when waiting for new events. |
1675 | active, the process will not block when waiting for new events. |
656 | |
1676 | |
657 | Apart from keeping your process non-blocking (which is a useful |
1677 | Apart from keeping your process non-blocking (which is a useful |
658 | effect on its own sometimes), idle watchers are a good place to do |
1678 | effect on its own sometimes), idle watchers are a good place to do |
659 | "pseudo-background processing", or delay processing stuff to after the |
1679 | "pseudo-background processing", or delay processing stuff to after the |
660 | event loop has handled all outstanding events. |
1680 | event loop has handled all outstanding events. |
661 | |
1681 | |
|
|
1682 | =head3 Watcher-Specific Functions and Data Members |
|
|
1683 | |
662 | =over 4 |
1684 | =over 4 |
663 | |
1685 | |
664 | =item ev_idle_init (ev_signal *, callback) |
1686 | =item ev_idle_init (ev_signal *, callback) |
665 | |
1687 | |
666 | Initialises and configures the idle watcher - it has no parameters of any |
1688 | Initialises and configures the idle watcher - it has no parameters of any |
667 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1689 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
668 | believe me. |
1690 | believe me. |
669 | |
1691 | |
670 | =back |
1692 | =back |
671 | |
1693 | |
672 | =head2 prepare and check - your hooks into the event loop |
1694 | =head3 Examples |
|
|
1695 | |
|
|
1696 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
|
|
1697 | callback, free it. Also, use no error checking, as usual. |
|
|
1698 | |
|
|
1699 | static void |
|
|
1700 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
|
|
1701 | { |
|
|
1702 | free (w); |
|
|
1703 | // now do something you wanted to do when the program has |
|
|
1704 | // no longer anything immediate to do. |
|
|
1705 | } |
|
|
1706 | |
|
|
1707 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
|
|
1708 | ev_idle_init (idle_watcher, idle_cb); |
|
|
1709 | ev_idle_start (loop, idle_cb); |
|
|
1710 | |
|
|
1711 | |
|
|
1712 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
673 | |
1713 | |
674 | Prepare and check watchers are usually (but not always) used in tandem: |
1714 | Prepare and check watchers are usually (but not always) used in tandem: |
675 | Prepare watchers get invoked before the process blocks and check watchers |
1715 | prepare watchers get invoked before the process blocks and check watchers |
676 | afterwards. |
1716 | afterwards. |
677 | |
1717 | |
|
|
1718 | You I<must not> call C<ev_loop> or similar functions that enter |
|
|
1719 | the current event loop from either C<ev_prepare> or C<ev_check> |
|
|
1720 | watchers. Other loops than the current one are fine, however. The |
|
|
1721 | rationale behind this is that you do not need to check for recursion in |
|
|
1722 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
|
|
1723 | C<ev_check> so if you have one watcher of each kind they will always be |
|
|
1724 | called in pairs bracketing the blocking call. |
|
|
1725 | |
678 | Their main purpose is to integrate other event mechanisms into libev. This |
1726 | Their main purpose is to integrate other event mechanisms into libev and |
679 | could be used, for example, to track variable changes, implement your own |
1727 | their use is somewhat advanced. This could be used, for example, to track |
680 | watchers, integrate net-snmp or a coroutine library and lots more. |
1728 | variable changes, implement your own watchers, integrate net-snmp or a |
|
|
1729 | coroutine library and lots more. They are also occasionally useful if |
|
|
1730 | you cache some data and want to flush it before blocking (for example, |
|
|
1731 | in X programs you might want to do an C<XFlush ()> in an C<ev_prepare> |
|
|
1732 | watcher). |
681 | |
1733 | |
682 | This is done by examining in each prepare call which file descriptors need |
1734 | This is done by examining in each prepare call which file descriptors need |
683 | to be watched by the other library, registering C<ev_io> watchers for |
1735 | to be watched by the other library, registering C<ev_io> watchers for |
684 | them and starting an C<ev_timer> watcher for any timeouts (many libraries |
1736 | them and starting an C<ev_timer> watcher for any timeouts (many libraries |
685 | provide just this functionality). Then, in the check watcher you check for |
1737 | provide just this functionality). Then, in the check watcher you check for |
686 | any events that occured (by checking the pending status of all watchers |
1738 | any events that occured (by checking the pending status of all watchers |
687 | and stopping them) and call back into the library. The I/O and timer |
1739 | and stopping them) and call back into the library. The I/O and timer |
688 | callbacks will never actually be called (but must be valid neverthelles, |
1740 | callbacks will never actually be called (but must be valid nevertheless, |
689 | because you never know, you know?). |
1741 | because you never know, you know?). |
690 | |
1742 | |
691 | As another example, the Perl Coro module uses these hooks to integrate |
1743 | As another example, the Perl Coro module uses these hooks to integrate |
692 | coroutines into libev programs, by yielding to other active coroutines |
1744 | coroutines into libev programs, by yielding to other active coroutines |
693 | during each prepare and only letting the process block if no coroutines |
1745 | during each prepare and only letting the process block if no coroutines |
694 | are ready to run (its actually more complicated, it only runs coroutines |
1746 | are ready to run (it's actually more complicated: it only runs coroutines |
695 | with priority higher than the event loop and one lower priority once, |
1747 | with priority higher than or equal to the event loop and one coroutine |
696 | using idle watchers to keep the event loop from blocking if lower-priority |
1748 | of lower priority, but only once, using idle watchers to keep the event |
697 | coroutines exist, thus mapping low-priority coroutines to idle/background |
1749 | loop from blocking if lower-priority coroutines are active, thus mapping |
698 | tasks). |
1750 | low-priority coroutines to idle/background tasks). |
|
|
1751 | |
|
|
1752 | It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>) |
|
|
1753 | priority, to ensure that they are being run before any other watchers |
|
|
1754 | after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers, |
|
|
1755 | too) should not activate ("feed") events into libev. While libev fully |
|
|
1756 | supports this, they will be called before other C<ev_check> watchers |
|
|
1757 | did their job. As C<ev_check> watchers are often used to embed other |
|
|
1758 | (non-libev) event loops those other event loops might be in an unusable |
|
|
1759 | state until their C<ev_check> watcher ran (always remind yourself to |
|
|
1760 | coexist peacefully with others). |
|
|
1761 | |
|
|
1762 | =head3 Watcher-Specific Functions and Data Members |
699 | |
1763 | |
700 | =over 4 |
1764 | =over 4 |
701 | |
1765 | |
702 | =item ev_prepare_init (ev_prepare *, callback) |
1766 | =item ev_prepare_init (ev_prepare *, callback) |
703 | |
1767 | |
… | |
… | |
707 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1771 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
708 | macros, but using them is utterly, utterly and completely pointless. |
1772 | macros, but using them is utterly, utterly and completely pointless. |
709 | |
1773 | |
710 | =back |
1774 | =back |
711 | |
1775 | |
|
|
1776 | =head3 Examples |
|
|
1777 | |
|
|
1778 | There are a number of principal ways to embed other event loops or modules |
|
|
1779 | into libev. Here are some ideas on how to include libadns into libev |
|
|
1780 | (there is a Perl module named C<EV::ADNS> that does this, which you could |
|
|
1781 | use for an actually working example. Another Perl module named C<EV::Glib> |
|
|
1782 | embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV |
|
|
1783 | into the Glib event loop). |
|
|
1784 | |
|
|
1785 | Method 1: Add IO watchers and a timeout watcher in a prepare handler, |
|
|
1786 | and in a check watcher, destroy them and call into libadns. What follows |
|
|
1787 | is pseudo-code only of course. This requires you to either use a low |
|
|
1788 | priority for the check watcher or use C<ev_clear_pending> explicitly, as |
|
|
1789 | the callbacks for the IO/timeout watchers might not have been called yet. |
|
|
1790 | |
|
|
1791 | static ev_io iow [nfd]; |
|
|
1792 | static ev_timer tw; |
|
|
1793 | |
|
|
1794 | static void |
|
|
1795 | io_cb (ev_loop *loop, ev_io *w, int revents) |
|
|
1796 | { |
|
|
1797 | } |
|
|
1798 | |
|
|
1799 | // create io watchers for each fd and a timer before blocking |
|
|
1800 | static void |
|
|
1801 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
|
|
1802 | { |
|
|
1803 | int timeout = 3600000; |
|
|
1804 | struct pollfd fds [nfd]; |
|
|
1805 | // actual code will need to loop here and realloc etc. |
|
|
1806 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
|
|
1807 | |
|
|
1808 | /* the callback is illegal, but won't be called as we stop during check */ |
|
|
1809 | ev_timer_init (&tw, 0, timeout * 1e-3); |
|
|
1810 | ev_timer_start (loop, &tw); |
|
|
1811 | |
|
|
1812 | // create one ev_io per pollfd |
|
|
1813 | for (int i = 0; i < nfd; ++i) |
|
|
1814 | { |
|
|
1815 | ev_io_init (iow + i, io_cb, fds [i].fd, |
|
|
1816 | ((fds [i].events & POLLIN ? EV_READ : 0) |
|
|
1817 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
|
|
1818 | |
|
|
1819 | fds [i].revents = 0; |
|
|
1820 | ev_io_start (loop, iow + i); |
|
|
1821 | } |
|
|
1822 | } |
|
|
1823 | |
|
|
1824 | // stop all watchers after blocking |
|
|
1825 | static void |
|
|
1826 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
|
|
1827 | { |
|
|
1828 | ev_timer_stop (loop, &tw); |
|
|
1829 | |
|
|
1830 | for (int i = 0; i < nfd; ++i) |
|
|
1831 | { |
|
|
1832 | // set the relevant poll flags |
|
|
1833 | // could also call adns_processreadable etc. here |
|
|
1834 | struct pollfd *fd = fds + i; |
|
|
1835 | int revents = ev_clear_pending (iow + i); |
|
|
1836 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1837 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1838 | |
|
|
1839 | // now stop the watcher |
|
|
1840 | ev_io_stop (loop, iow + i); |
|
|
1841 | } |
|
|
1842 | |
|
|
1843 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
1844 | } |
|
|
1845 | |
|
|
1846 | Method 2: This would be just like method 1, but you run C<adns_afterpoll> |
|
|
1847 | in the prepare watcher and would dispose of the check watcher. |
|
|
1848 | |
|
|
1849 | Method 3: If the module to be embedded supports explicit event |
|
|
1850 | notification (adns does), you can also make use of the actual watcher |
|
|
1851 | callbacks, and only destroy/create the watchers in the prepare watcher. |
|
|
1852 | |
|
|
1853 | static void |
|
|
1854 | timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1855 | { |
|
|
1856 | adns_state ads = (adns_state)w->data; |
|
|
1857 | update_now (EV_A); |
|
|
1858 | |
|
|
1859 | adns_processtimeouts (ads, &tv_now); |
|
|
1860 | } |
|
|
1861 | |
|
|
1862 | static void |
|
|
1863 | io_cb (EV_P_ ev_io *w, int revents) |
|
|
1864 | { |
|
|
1865 | adns_state ads = (adns_state)w->data; |
|
|
1866 | update_now (EV_A); |
|
|
1867 | |
|
|
1868 | if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now); |
|
|
1869 | if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now); |
|
|
1870 | } |
|
|
1871 | |
|
|
1872 | // do not ever call adns_afterpoll |
|
|
1873 | |
|
|
1874 | Method 4: Do not use a prepare or check watcher because the module you |
|
|
1875 | want to embed is too inflexible to support it. Instead, youc na override |
|
|
1876 | their poll function. The drawback with this solution is that the main |
|
|
1877 | loop is now no longer controllable by EV. The C<Glib::EV> module does |
|
|
1878 | this. |
|
|
1879 | |
|
|
1880 | static gint |
|
|
1881 | event_poll_func (GPollFD *fds, guint nfds, gint timeout) |
|
|
1882 | { |
|
|
1883 | int got_events = 0; |
|
|
1884 | |
|
|
1885 | for (n = 0; n < nfds; ++n) |
|
|
1886 | // create/start io watcher that sets the relevant bits in fds[n] and increment got_events |
|
|
1887 | |
|
|
1888 | if (timeout >= 0) |
|
|
1889 | // create/start timer |
|
|
1890 | |
|
|
1891 | // poll |
|
|
1892 | ev_loop (EV_A_ 0); |
|
|
1893 | |
|
|
1894 | // stop timer again |
|
|
1895 | if (timeout >= 0) |
|
|
1896 | ev_timer_stop (EV_A_ &to); |
|
|
1897 | |
|
|
1898 | // stop io watchers again - their callbacks should have set |
|
|
1899 | for (n = 0; n < nfds; ++n) |
|
|
1900 | ev_io_stop (EV_A_ iow [n]); |
|
|
1901 | |
|
|
1902 | return got_events; |
|
|
1903 | } |
|
|
1904 | |
|
|
1905 | |
|
|
1906 | =head2 C<ev_embed> - when one backend isn't enough... |
|
|
1907 | |
|
|
1908 | This is a rather advanced watcher type that lets you embed one event loop |
|
|
1909 | into another (currently only C<ev_io> events are supported in the embedded |
|
|
1910 | loop, other types of watchers might be handled in a delayed or incorrect |
|
|
1911 | fashion and must not be used). |
|
|
1912 | |
|
|
1913 | There are primarily two reasons you would want that: work around bugs and |
|
|
1914 | prioritise I/O. |
|
|
1915 | |
|
|
1916 | As an example for a bug workaround, the kqueue backend might only support |
|
|
1917 | sockets on some platform, so it is unusable as generic backend, but you |
|
|
1918 | still want to make use of it because you have many sockets and it scales |
|
|
1919 | so nicely. In this case, you would create a kqueue-based loop and embed it |
|
|
1920 | into your default loop (which might use e.g. poll). Overall operation will |
|
|
1921 | be a bit slower because first libev has to poll and then call kevent, but |
|
|
1922 | at least you can use both at what they are best. |
|
|
1923 | |
|
|
1924 | As for prioritising I/O: rarely you have the case where some fds have |
|
|
1925 | to be watched and handled very quickly (with low latency), and even |
|
|
1926 | priorities and idle watchers might have too much overhead. In this case |
|
|
1927 | you would put all the high priority stuff in one loop and all the rest in |
|
|
1928 | a second one, and embed the second one in the first. |
|
|
1929 | |
|
|
1930 | As long as the watcher is active, the callback will be invoked every time |
|
|
1931 | there might be events pending in the embedded loop. The callback must then |
|
|
1932 | call C<ev_embed_sweep (mainloop, watcher)> to make a single sweep and invoke |
|
|
1933 | their callbacks (you could also start an idle watcher to give the embedded |
|
|
1934 | loop strictly lower priority for example). You can also set the callback |
|
|
1935 | to C<0>, in which case the embed watcher will automatically execute the |
|
|
1936 | embedded loop sweep. |
|
|
1937 | |
|
|
1938 | As long as the watcher is started it will automatically handle events. The |
|
|
1939 | callback will be invoked whenever some events have been handled. You can |
|
|
1940 | set the callback to C<0> to avoid having to specify one if you are not |
|
|
1941 | interested in that. |
|
|
1942 | |
|
|
1943 | Also, there have not currently been made special provisions for forking: |
|
|
1944 | when you fork, you not only have to call C<ev_loop_fork> on both loops, |
|
|
1945 | but you will also have to stop and restart any C<ev_embed> watchers |
|
|
1946 | yourself. |
|
|
1947 | |
|
|
1948 | Unfortunately, not all backends are embeddable, only the ones returned by |
|
|
1949 | C<ev_embeddable_backends> are, which, unfortunately, does not include any |
|
|
1950 | portable one. |
|
|
1951 | |
|
|
1952 | So when you want to use this feature you will always have to be prepared |
|
|
1953 | that you cannot get an embeddable loop. The recommended way to get around |
|
|
1954 | this is to have a separate variables for your embeddable loop, try to |
|
|
1955 | create it, and if that fails, use the normal loop for everything. |
|
|
1956 | |
|
|
1957 | =head3 Watcher-Specific Functions and Data Members |
|
|
1958 | |
|
|
1959 | =over 4 |
|
|
1960 | |
|
|
1961 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
1962 | |
|
|
1963 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
1964 | |
|
|
1965 | Configures the watcher to embed the given loop, which must be |
|
|
1966 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
|
|
1967 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
1968 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
1969 | if you do not want thta, you need to temporarily stop the embed watcher). |
|
|
1970 | |
|
|
1971 | =item ev_embed_sweep (loop, ev_embed *) |
|
|
1972 | |
|
|
1973 | Make a single, non-blocking sweep over the embedded loop. This works |
|
|
1974 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
|
|
1975 | apropriate way for embedded loops. |
|
|
1976 | |
|
|
1977 | =item struct ev_loop *other [read-only] |
|
|
1978 | |
|
|
1979 | The embedded event loop. |
|
|
1980 | |
|
|
1981 | =back |
|
|
1982 | |
|
|
1983 | =head3 Examples |
|
|
1984 | |
|
|
1985 | Example: Try to get an embeddable event loop and embed it into the default |
|
|
1986 | event loop. If that is not possible, use the default loop. The default |
|
|
1987 | loop is stored in C<loop_hi>, while the mebeddable loop is stored in |
|
|
1988 | C<loop_lo> (which is C<loop_hi> in the acse no embeddable loop can be |
|
|
1989 | used). |
|
|
1990 | |
|
|
1991 | struct ev_loop *loop_hi = ev_default_init (0); |
|
|
1992 | struct ev_loop *loop_lo = 0; |
|
|
1993 | struct ev_embed embed; |
|
|
1994 | |
|
|
1995 | // see if there is a chance of getting one that works |
|
|
1996 | // (remember that a flags value of 0 means autodetection) |
|
|
1997 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
|
|
1998 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
|
|
1999 | : 0; |
|
|
2000 | |
|
|
2001 | // if we got one, then embed it, otherwise default to loop_hi |
|
|
2002 | if (loop_lo) |
|
|
2003 | { |
|
|
2004 | ev_embed_init (&embed, 0, loop_lo); |
|
|
2005 | ev_embed_start (loop_hi, &embed); |
|
|
2006 | } |
|
|
2007 | else |
|
|
2008 | loop_lo = loop_hi; |
|
|
2009 | |
|
|
2010 | Example: Check if kqueue is available but not recommended and create |
|
|
2011 | a kqueue backend for use with sockets (which usually work with any |
|
|
2012 | kqueue implementation). Store the kqueue/socket-only event loop in |
|
|
2013 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
|
|
2014 | |
|
|
2015 | struct ev_loop *loop = ev_default_init (0); |
|
|
2016 | struct ev_loop *loop_socket = 0; |
|
|
2017 | struct ev_embed embed; |
|
|
2018 | |
|
|
2019 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
|
|
2020 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
|
|
2021 | { |
|
|
2022 | ev_embed_init (&embed, 0, loop_socket); |
|
|
2023 | ev_embed_start (loop, &embed); |
|
|
2024 | } |
|
|
2025 | |
|
|
2026 | if (!loop_socket) |
|
|
2027 | loop_socket = loop; |
|
|
2028 | |
|
|
2029 | // now use loop_socket for all sockets, and loop for everything else |
|
|
2030 | |
|
|
2031 | |
|
|
2032 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
|
|
2033 | |
|
|
2034 | Fork watchers are called when a C<fork ()> was detected (usually because |
|
|
2035 | whoever is a good citizen cared to tell libev about it by calling |
|
|
2036 | C<ev_default_fork> or C<ev_loop_fork>). The invocation is done before the |
|
|
2037 | event loop blocks next and before C<ev_check> watchers are being called, |
|
|
2038 | and only in the child after the fork. If whoever good citizen calling |
|
|
2039 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
|
|
2040 | handlers will be invoked, too, of course. |
|
|
2041 | |
|
|
2042 | =head3 Watcher-Specific Functions and Data Members |
|
|
2043 | |
|
|
2044 | =over 4 |
|
|
2045 | |
|
|
2046 | =item ev_fork_init (ev_signal *, callback) |
|
|
2047 | |
|
|
2048 | Initialises and configures the fork watcher - it has no parameters of any |
|
|
2049 | kind. There is a C<ev_fork_set> macro, but using it is utterly pointless, |
|
|
2050 | believe me. |
|
|
2051 | |
|
|
2052 | =back |
|
|
2053 | |
|
|
2054 | |
|
|
2055 | =head2 C<ev_async> - how to wake up another event loop |
|
|
2056 | |
|
|
2057 | In general, you cannot use an C<ev_loop> from multiple threads or other |
|
|
2058 | asynchronous sources such as signal handlers (as opposed to multiple event |
|
|
2059 | loops - those are of course safe to use in different threads). |
|
|
2060 | |
|
|
2061 | Sometimes, however, you need to wake up another event loop you do not |
|
|
2062 | control, for example because it belongs to another thread. This is what |
|
|
2063 | C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you |
|
|
2064 | can signal it by calling C<ev_async_send>, which is thread- and signal |
|
|
2065 | safe. |
|
|
2066 | |
|
|
2067 | This functionality is very similar to C<ev_signal> watchers, as signals, |
|
|
2068 | too, are asynchronous in nature, and signals, too, will be compressed |
|
|
2069 | (i.e. the number of callback invocations may be less than the number of |
|
|
2070 | C<ev_async_sent> calls). |
|
|
2071 | |
|
|
2072 | Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not |
|
|
2073 | just the default loop. |
|
|
2074 | |
|
|
2075 | =head3 Queueing |
|
|
2076 | |
|
|
2077 | C<ev_async> does not support queueing of data in any way. The reason |
|
|
2078 | is that the author does not know of a simple (or any) algorithm for a |
|
|
2079 | multiple-writer-single-reader queue that works in all cases and doesn't |
|
|
2080 | need elaborate support such as pthreads. |
|
|
2081 | |
|
|
2082 | That means that if you want to queue data, you have to provide your own |
|
|
2083 | queue. But at least I can tell you would implement locking around your |
|
|
2084 | queue: |
|
|
2085 | |
|
|
2086 | =over 4 |
|
|
2087 | |
|
|
2088 | =item queueing from a signal handler context |
|
|
2089 | |
|
|
2090 | To implement race-free queueing, you simply add to the queue in the signal |
|
|
2091 | handler but you block the signal handler in the watcher callback. Here is an example that does that for |
|
|
2092 | some fictitiuous SIGUSR1 handler: |
|
|
2093 | |
|
|
2094 | static ev_async mysig; |
|
|
2095 | |
|
|
2096 | static void |
|
|
2097 | sigusr1_handler (void) |
|
|
2098 | { |
|
|
2099 | sometype data; |
|
|
2100 | |
|
|
2101 | // no locking etc. |
|
|
2102 | queue_put (data); |
|
|
2103 | ev_async_send (DEFAULT_ &mysig); |
|
|
2104 | } |
|
|
2105 | |
|
|
2106 | static void |
|
|
2107 | mysig_cb (EV_P_ ev_async *w, int revents) |
|
|
2108 | { |
|
|
2109 | sometype data; |
|
|
2110 | sigset_t block, prev; |
|
|
2111 | |
|
|
2112 | sigemptyset (&block); |
|
|
2113 | sigaddset (&block, SIGUSR1); |
|
|
2114 | sigprocmask (SIG_BLOCK, &block, &prev); |
|
|
2115 | |
|
|
2116 | while (queue_get (&data)) |
|
|
2117 | process (data); |
|
|
2118 | |
|
|
2119 | if (sigismember (&prev, SIGUSR1) |
|
|
2120 | sigprocmask (SIG_UNBLOCK, &block, 0); |
|
|
2121 | } |
|
|
2122 | |
|
|
2123 | (Note: pthreads in theory requires you to use C<pthread_setmask> |
|
|
2124 | instead of C<sigprocmask> when you use threads, but libev doesn't do it |
|
|
2125 | either...). |
|
|
2126 | |
|
|
2127 | =item queueing from a thread context |
|
|
2128 | |
|
|
2129 | The strategy for threads is different, as you cannot (easily) block |
|
|
2130 | threads but you can easily preempt them, so to queue safely you need to |
|
|
2131 | employ a traditional mutex lock, such as in this pthread example: |
|
|
2132 | |
|
|
2133 | static ev_async mysig; |
|
|
2134 | static pthread_mutex_t mymutex = PTHREAD_MUTEX_INITIALIZER; |
|
|
2135 | |
|
|
2136 | static void |
|
|
2137 | otherthread (void) |
|
|
2138 | { |
|
|
2139 | // only need to lock the actual queueing operation |
|
|
2140 | pthread_mutex_lock (&mymutex); |
|
|
2141 | queue_put (data); |
|
|
2142 | pthread_mutex_unlock (&mymutex); |
|
|
2143 | |
|
|
2144 | ev_async_send (DEFAULT_ &mysig); |
|
|
2145 | } |
|
|
2146 | |
|
|
2147 | static void |
|
|
2148 | mysig_cb (EV_P_ ev_async *w, int revents) |
|
|
2149 | { |
|
|
2150 | pthread_mutex_lock (&mymutex); |
|
|
2151 | |
|
|
2152 | while (queue_get (&data)) |
|
|
2153 | process (data); |
|
|
2154 | |
|
|
2155 | pthread_mutex_unlock (&mymutex); |
|
|
2156 | } |
|
|
2157 | |
|
|
2158 | =back |
|
|
2159 | |
|
|
2160 | |
|
|
2161 | =head3 Watcher-Specific Functions and Data Members |
|
|
2162 | |
|
|
2163 | =over 4 |
|
|
2164 | |
|
|
2165 | =item ev_async_init (ev_async *, callback) |
|
|
2166 | |
|
|
2167 | Initialises and configures the async watcher - it has no parameters of any |
|
|
2168 | kind. There is a C<ev_asynd_set> macro, but using it is utterly pointless, |
|
|
2169 | believe me. |
|
|
2170 | |
|
|
2171 | =item ev_async_send (loop, ev_async *) |
|
|
2172 | |
|
|
2173 | Sends/signals/activates the given C<ev_async> watcher, that is, feeds |
|
|
2174 | an C<EV_ASYNC> event on the watcher into the event loop. Unlike |
|
|
2175 | C<ev_feed_event>, this call is safe to do in other threads, signal or |
|
|
2176 | similar contexts (see the dicusssion of C<EV_ATOMIC_T> in the embedding |
|
|
2177 | section below on what exactly this means). |
|
|
2178 | |
|
|
2179 | This call incurs the overhead of a syscall only once per loop iteration, |
|
|
2180 | so while the overhead might be noticable, it doesn't apply to repeated |
|
|
2181 | calls to C<ev_async_send>. |
|
|
2182 | |
|
|
2183 | =back |
|
|
2184 | |
|
|
2185 | |
712 | =head1 OTHER FUNCTIONS |
2186 | =head1 OTHER FUNCTIONS |
713 | |
2187 | |
714 | There are some other functions of possible interest. Described. Here. Now. |
2188 | There are some other functions of possible interest. Described. Here. Now. |
715 | |
2189 | |
716 | =over 4 |
2190 | =over 4 |
… | |
… | |
718 | =item ev_once (loop, int fd, int events, ev_tstamp timeout, callback) |
2192 | =item ev_once (loop, int fd, int events, ev_tstamp timeout, callback) |
719 | |
2193 | |
720 | This function combines a simple timer and an I/O watcher, calls your |
2194 | This function combines a simple timer and an I/O watcher, calls your |
721 | callback on whichever event happens first and automatically stop both |
2195 | callback on whichever event happens first and automatically stop both |
722 | watchers. This is useful if you want to wait for a single event on an fd |
2196 | watchers. This is useful if you want to wait for a single event on an fd |
723 | or timeout without havign to allocate/configure/start/stop/free one or |
2197 | or timeout without having to allocate/configure/start/stop/free one or |
724 | more watchers yourself. |
2198 | more watchers yourself. |
725 | |
2199 | |
726 | If C<fd> is less than 0, then no I/O watcher will be started and events |
2200 | If C<fd> is less than 0, then no I/O watcher will be started and events |
727 | is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and |
2201 | is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and |
728 | C<events> set will be craeted and started. |
2202 | C<events> set will be craeted and started. |
… | |
… | |
731 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
2205 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
732 | repeat = 0) will be started. While C<0> is a valid timeout, it is of |
2206 | repeat = 0) will be started. While C<0> is a valid timeout, it is of |
733 | dubious value. |
2207 | dubious value. |
734 | |
2208 | |
735 | The callback has the type C<void (*cb)(int revents, void *arg)> and gets |
2209 | The callback has the type C<void (*cb)(int revents, void *arg)> and gets |
736 | passed an events set like normal event callbacks (with a combination of |
2210 | passed an C<revents> set like normal event callbacks (a combination of |
737 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg> |
2211 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg> |
738 | value passed to C<ev_once>: |
2212 | value passed to C<ev_once>: |
739 | |
2213 | |
740 | static void stdin_ready (int revents, void *arg) |
2214 | static void stdin_ready (int revents, void *arg) |
741 | { |
2215 | { |
… | |
… | |
745 | /* stdin might have data for us, joy! */; |
2219 | /* stdin might have data for us, joy! */; |
746 | } |
2220 | } |
747 | |
2221 | |
748 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
2222 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
749 | |
2223 | |
750 | =item ev_feed_event (loop, watcher, int events) |
2224 | =item ev_feed_event (ev_loop *, watcher *, int revents) |
751 | |
2225 | |
752 | Feeds the given event set into the event loop, as if the specified event |
2226 | Feeds the given event set into the event loop, as if the specified event |
753 | had happened for the specified watcher (which must be a pointer to an |
2227 | had happened for the specified watcher (which must be a pointer to an |
754 | initialised but not necessarily started event watcher). |
2228 | initialised but not necessarily started event watcher). |
755 | |
2229 | |
756 | =item ev_feed_fd_event (loop, int fd, int revents) |
2230 | =item ev_feed_fd_event (ev_loop *, int fd, int revents) |
757 | |
2231 | |
758 | Feed an event on the given fd, as if a file descriptor backend detected |
2232 | Feed an event on the given fd, as if a file descriptor backend detected |
759 | the given events it. |
2233 | the given events it. |
760 | |
2234 | |
761 | =item ev_feed_signal_event (loop, int signum) |
2235 | =item ev_feed_signal_event (ev_loop *loop, int signum) |
762 | |
2236 | |
763 | Feed an event as if the given signal occured (loop must be the default loop!). |
2237 | Feed an event as if the given signal occured (C<loop> must be the default |
|
|
2238 | loop!). |
764 | |
2239 | |
765 | =back |
2240 | =back |
766 | |
2241 | |
|
|
2242 | |
|
|
2243 | =head1 LIBEVENT EMULATION |
|
|
2244 | |
|
|
2245 | Libev offers a compatibility emulation layer for libevent. It cannot |
|
|
2246 | emulate the internals of libevent, so here are some usage hints: |
|
|
2247 | |
|
|
2248 | =over 4 |
|
|
2249 | |
|
|
2250 | =item * Use it by including <event.h>, as usual. |
|
|
2251 | |
|
|
2252 | =item * The following members are fully supported: ev_base, ev_callback, |
|
|
2253 | ev_arg, ev_fd, ev_res, ev_events. |
|
|
2254 | |
|
|
2255 | =item * Avoid using ev_flags and the EVLIST_*-macros, while it is |
|
|
2256 | maintained by libev, it does not work exactly the same way as in libevent (consider |
|
|
2257 | it a private API). |
|
|
2258 | |
|
|
2259 | =item * Priorities are not currently supported. Initialising priorities |
|
|
2260 | will fail and all watchers will have the same priority, even though there |
|
|
2261 | is an ev_pri field. |
|
|
2262 | |
|
|
2263 | =item * Other members are not supported. |
|
|
2264 | |
|
|
2265 | =item * The libev emulation is I<not> ABI compatible to libevent, you need |
|
|
2266 | to use the libev header file and library. |
|
|
2267 | |
|
|
2268 | =back |
|
|
2269 | |
|
|
2270 | =head1 C++ SUPPORT |
|
|
2271 | |
|
|
2272 | Libev comes with some simplistic wrapper classes for C++ that mainly allow |
|
|
2273 | you to use some convinience methods to start/stop watchers and also change |
|
|
2274 | the callback model to a model using method callbacks on objects. |
|
|
2275 | |
|
|
2276 | To use it, |
|
|
2277 | |
|
|
2278 | #include <ev++.h> |
|
|
2279 | |
|
|
2280 | This automatically includes F<ev.h> and puts all of its definitions (many |
|
|
2281 | of them macros) into the global namespace. All C++ specific things are |
|
|
2282 | put into the C<ev> namespace. It should support all the same embedding |
|
|
2283 | options as F<ev.h>, most notably C<EV_MULTIPLICITY>. |
|
|
2284 | |
|
|
2285 | Care has been taken to keep the overhead low. The only data member the C++ |
|
|
2286 | classes add (compared to plain C-style watchers) is the event loop pointer |
|
|
2287 | that the watcher is associated with (or no additional members at all if |
|
|
2288 | you disable C<EV_MULTIPLICITY> when embedding libev). |
|
|
2289 | |
|
|
2290 | Currently, functions, and static and non-static member functions can be |
|
|
2291 | used as callbacks. Other types should be easy to add as long as they only |
|
|
2292 | need one additional pointer for context. If you need support for other |
|
|
2293 | types of functors please contact the author (preferably after implementing |
|
|
2294 | it). |
|
|
2295 | |
|
|
2296 | Here is a list of things available in the C<ev> namespace: |
|
|
2297 | |
|
|
2298 | =over 4 |
|
|
2299 | |
|
|
2300 | =item C<ev::READ>, C<ev::WRITE> etc. |
|
|
2301 | |
|
|
2302 | These are just enum values with the same values as the C<EV_READ> etc. |
|
|
2303 | macros from F<ev.h>. |
|
|
2304 | |
|
|
2305 | =item C<ev::tstamp>, C<ev::now> |
|
|
2306 | |
|
|
2307 | Aliases to the same types/functions as with the C<ev_> prefix. |
|
|
2308 | |
|
|
2309 | =item C<ev::io>, C<ev::timer>, C<ev::periodic>, C<ev::idle>, C<ev::sig> etc. |
|
|
2310 | |
|
|
2311 | For each C<ev_TYPE> watcher in F<ev.h> there is a corresponding class of |
|
|
2312 | the same name in the C<ev> namespace, with the exception of C<ev_signal> |
|
|
2313 | which is called C<ev::sig> to avoid clashes with the C<signal> macro |
|
|
2314 | defines by many implementations. |
|
|
2315 | |
|
|
2316 | All of those classes have these methods: |
|
|
2317 | |
|
|
2318 | =over 4 |
|
|
2319 | |
|
|
2320 | =item ev::TYPE::TYPE () |
|
|
2321 | |
|
|
2322 | =item ev::TYPE::TYPE (struct ev_loop *) |
|
|
2323 | |
|
|
2324 | =item ev::TYPE::~TYPE |
|
|
2325 | |
|
|
2326 | The constructor (optionally) takes an event loop to associate the watcher |
|
|
2327 | with. If it is omitted, it will use C<EV_DEFAULT>. |
|
|
2328 | |
|
|
2329 | The constructor calls C<ev_init> for you, which means you have to call the |
|
|
2330 | C<set> method before starting it. |
|
|
2331 | |
|
|
2332 | It will not set a callback, however: You have to call the templated C<set> |
|
|
2333 | method to set a callback before you can start the watcher. |
|
|
2334 | |
|
|
2335 | (The reason why you have to use a method is a limitation in C++ which does |
|
|
2336 | not allow explicit template arguments for constructors). |
|
|
2337 | |
|
|
2338 | The destructor automatically stops the watcher if it is active. |
|
|
2339 | |
|
|
2340 | =item w->set<class, &class::method> (object *) |
|
|
2341 | |
|
|
2342 | This method sets the callback method to call. The method has to have a |
|
|
2343 | signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as |
|
|
2344 | first argument and the C<revents> as second. The object must be given as |
|
|
2345 | parameter and is stored in the C<data> member of the watcher. |
|
|
2346 | |
|
|
2347 | This method synthesizes efficient thunking code to call your method from |
|
|
2348 | the C callback that libev requires. If your compiler can inline your |
|
|
2349 | callback (i.e. it is visible to it at the place of the C<set> call and |
|
|
2350 | your compiler is good :), then the method will be fully inlined into the |
|
|
2351 | thunking function, making it as fast as a direct C callback. |
|
|
2352 | |
|
|
2353 | Example: simple class declaration and watcher initialisation |
|
|
2354 | |
|
|
2355 | struct myclass |
|
|
2356 | { |
|
|
2357 | void io_cb (ev::io &w, int revents) { } |
|
|
2358 | } |
|
|
2359 | |
|
|
2360 | myclass obj; |
|
|
2361 | ev::io iow; |
|
|
2362 | iow.set <myclass, &myclass::io_cb> (&obj); |
|
|
2363 | |
|
|
2364 | =item w->set<function> (void *data = 0) |
|
|
2365 | |
|
|
2366 | Also sets a callback, but uses a static method or plain function as |
|
|
2367 | callback. The optional C<data> argument will be stored in the watcher's |
|
|
2368 | C<data> member and is free for you to use. |
|
|
2369 | |
|
|
2370 | The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>. |
|
|
2371 | |
|
|
2372 | See the method-C<set> above for more details. |
|
|
2373 | |
|
|
2374 | Example: |
|
|
2375 | |
|
|
2376 | static void io_cb (ev::io &w, int revents) { } |
|
|
2377 | iow.set <io_cb> (); |
|
|
2378 | |
|
|
2379 | =item w->set (struct ev_loop *) |
|
|
2380 | |
|
|
2381 | Associates a different C<struct ev_loop> with this watcher. You can only |
|
|
2382 | do this when the watcher is inactive (and not pending either). |
|
|
2383 | |
|
|
2384 | =item w->set ([args]) |
|
|
2385 | |
|
|
2386 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
|
|
2387 | called at least once. Unlike the C counterpart, an active watcher gets |
|
|
2388 | automatically stopped and restarted when reconfiguring it with this |
|
|
2389 | method. |
|
|
2390 | |
|
|
2391 | =item w->start () |
|
|
2392 | |
|
|
2393 | Starts the watcher. Note that there is no C<loop> argument, as the |
|
|
2394 | constructor already stores the event loop. |
|
|
2395 | |
|
|
2396 | =item w->stop () |
|
|
2397 | |
|
|
2398 | Stops the watcher if it is active. Again, no C<loop> argument. |
|
|
2399 | |
|
|
2400 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
|
|
2401 | |
|
|
2402 | For C<ev::timer> and C<ev::periodic>, this invokes the corresponding |
|
|
2403 | C<ev_TYPE_again> function. |
|
|
2404 | |
|
|
2405 | =item w->sweep () (C<ev::embed> only) |
|
|
2406 | |
|
|
2407 | Invokes C<ev_embed_sweep>. |
|
|
2408 | |
|
|
2409 | =item w->update () (C<ev::stat> only) |
|
|
2410 | |
|
|
2411 | Invokes C<ev_stat_stat>. |
|
|
2412 | |
|
|
2413 | =back |
|
|
2414 | |
|
|
2415 | =back |
|
|
2416 | |
|
|
2417 | Example: Define a class with an IO and idle watcher, start one of them in |
|
|
2418 | the constructor. |
|
|
2419 | |
|
|
2420 | class myclass |
|
|
2421 | { |
|
|
2422 | ev::io io; void io_cb (ev::io &w, int revents); |
|
|
2423 | ev:idle idle void idle_cb (ev::idle &w, int revents); |
|
|
2424 | |
|
|
2425 | myclass (int fd) |
|
|
2426 | { |
|
|
2427 | io .set <myclass, &myclass::io_cb > (this); |
|
|
2428 | idle.set <myclass, &myclass::idle_cb> (this); |
|
|
2429 | |
|
|
2430 | io.start (fd, ev::READ); |
|
|
2431 | } |
|
|
2432 | }; |
|
|
2433 | |
|
|
2434 | |
|
|
2435 | =head1 MACRO MAGIC |
|
|
2436 | |
|
|
2437 | Libev can be compiled with a variety of options, the most fundamantal |
|
|
2438 | of which is C<EV_MULTIPLICITY>. This option determines whether (most) |
|
|
2439 | functions and callbacks have an initial C<struct ev_loop *> argument. |
|
|
2440 | |
|
|
2441 | To make it easier to write programs that cope with either variant, the |
|
|
2442 | following macros are defined: |
|
|
2443 | |
|
|
2444 | =over 4 |
|
|
2445 | |
|
|
2446 | =item C<EV_A>, C<EV_A_> |
|
|
2447 | |
|
|
2448 | This provides the loop I<argument> for functions, if one is required ("ev |
|
|
2449 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
|
|
2450 | C<EV_A_> is used when other arguments are following. Example: |
|
|
2451 | |
|
|
2452 | ev_unref (EV_A); |
|
|
2453 | ev_timer_add (EV_A_ watcher); |
|
|
2454 | ev_loop (EV_A_ 0); |
|
|
2455 | |
|
|
2456 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
|
|
2457 | which is often provided by the following macro. |
|
|
2458 | |
|
|
2459 | =item C<EV_P>, C<EV_P_> |
|
|
2460 | |
|
|
2461 | This provides the loop I<parameter> for functions, if one is required ("ev |
|
|
2462 | loop parameter"). The C<EV_P> form is used when this is the sole parameter, |
|
|
2463 | C<EV_P_> is used when other parameters are following. Example: |
|
|
2464 | |
|
|
2465 | // this is how ev_unref is being declared |
|
|
2466 | static void ev_unref (EV_P); |
|
|
2467 | |
|
|
2468 | // this is how you can declare your typical callback |
|
|
2469 | static void cb (EV_P_ ev_timer *w, int revents) |
|
|
2470 | |
|
|
2471 | It declares a parameter C<loop> of type C<struct ev_loop *>, quite |
|
|
2472 | suitable for use with C<EV_A>. |
|
|
2473 | |
|
|
2474 | =item C<EV_DEFAULT>, C<EV_DEFAULT_> |
|
|
2475 | |
|
|
2476 | Similar to the other two macros, this gives you the value of the default |
|
|
2477 | loop, if multiple loops are supported ("ev loop default"). |
|
|
2478 | |
|
|
2479 | =back |
|
|
2480 | |
|
|
2481 | Example: Declare and initialise a check watcher, utilising the above |
|
|
2482 | macros so it will work regardless of whether multiple loops are supported |
|
|
2483 | or not. |
|
|
2484 | |
|
|
2485 | static void |
|
|
2486 | check_cb (EV_P_ ev_timer *w, int revents) |
|
|
2487 | { |
|
|
2488 | ev_check_stop (EV_A_ w); |
|
|
2489 | } |
|
|
2490 | |
|
|
2491 | ev_check check; |
|
|
2492 | ev_check_init (&check, check_cb); |
|
|
2493 | ev_check_start (EV_DEFAULT_ &check); |
|
|
2494 | ev_loop (EV_DEFAULT_ 0); |
|
|
2495 | |
|
|
2496 | =head1 EMBEDDING |
|
|
2497 | |
|
|
2498 | Libev can (and often is) directly embedded into host |
|
|
2499 | applications. Examples of applications that embed it include the Deliantra |
|
|
2500 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
|
|
2501 | and rxvt-unicode. |
|
|
2502 | |
|
|
2503 | The goal is to enable you to just copy the necessary files into your |
|
|
2504 | source directory without having to change even a single line in them, so |
|
|
2505 | you can easily upgrade by simply copying (or having a checked-out copy of |
|
|
2506 | libev somewhere in your source tree). |
|
|
2507 | |
|
|
2508 | =head2 FILESETS |
|
|
2509 | |
|
|
2510 | Depending on what features you need you need to include one or more sets of files |
|
|
2511 | in your app. |
|
|
2512 | |
|
|
2513 | =head3 CORE EVENT LOOP |
|
|
2514 | |
|
|
2515 | To include only the libev core (all the C<ev_*> functions), with manual |
|
|
2516 | configuration (no autoconf): |
|
|
2517 | |
|
|
2518 | #define EV_STANDALONE 1 |
|
|
2519 | #include "ev.c" |
|
|
2520 | |
|
|
2521 | This will automatically include F<ev.h>, too, and should be done in a |
|
|
2522 | single C source file only to provide the function implementations. To use |
|
|
2523 | it, do the same for F<ev.h> in all files wishing to use this API (best |
|
|
2524 | done by writing a wrapper around F<ev.h> that you can include instead and |
|
|
2525 | where you can put other configuration options): |
|
|
2526 | |
|
|
2527 | #define EV_STANDALONE 1 |
|
|
2528 | #include "ev.h" |
|
|
2529 | |
|
|
2530 | Both header files and implementation files can be compiled with a C++ |
|
|
2531 | compiler (at least, thats a stated goal, and breakage will be treated |
|
|
2532 | as a bug). |
|
|
2533 | |
|
|
2534 | You need the following files in your source tree, or in a directory |
|
|
2535 | in your include path (e.g. in libev/ when using -Ilibev): |
|
|
2536 | |
|
|
2537 | ev.h |
|
|
2538 | ev.c |
|
|
2539 | ev_vars.h |
|
|
2540 | ev_wrap.h |
|
|
2541 | |
|
|
2542 | ev_win32.c required on win32 platforms only |
|
|
2543 | |
|
|
2544 | ev_select.c only when select backend is enabled (which is enabled by default) |
|
|
2545 | ev_poll.c only when poll backend is enabled (disabled by default) |
|
|
2546 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
|
|
2547 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
|
|
2548 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
|
|
2549 | |
|
|
2550 | F<ev.c> includes the backend files directly when enabled, so you only need |
|
|
2551 | to compile this single file. |
|
|
2552 | |
|
|
2553 | =head3 LIBEVENT COMPATIBILITY API |
|
|
2554 | |
|
|
2555 | To include the libevent compatibility API, also include: |
|
|
2556 | |
|
|
2557 | #include "event.c" |
|
|
2558 | |
|
|
2559 | in the file including F<ev.c>, and: |
|
|
2560 | |
|
|
2561 | #include "event.h" |
|
|
2562 | |
|
|
2563 | in the files that want to use the libevent API. This also includes F<ev.h>. |
|
|
2564 | |
|
|
2565 | You need the following additional files for this: |
|
|
2566 | |
|
|
2567 | event.h |
|
|
2568 | event.c |
|
|
2569 | |
|
|
2570 | =head3 AUTOCONF SUPPORT |
|
|
2571 | |
|
|
2572 | Instead of using C<EV_STANDALONE=1> and providing your config in |
|
|
2573 | whatever way you want, you can also C<m4_include([libev.m4])> in your |
|
|
2574 | F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then |
|
|
2575 | include F<config.h> and configure itself accordingly. |
|
|
2576 | |
|
|
2577 | For this of course you need the m4 file: |
|
|
2578 | |
|
|
2579 | libev.m4 |
|
|
2580 | |
|
|
2581 | =head2 PREPROCESSOR SYMBOLS/MACROS |
|
|
2582 | |
|
|
2583 | Libev can be configured via a variety of preprocessor symbols you have to define |
|
|
2584 | before including any of its files. The default is not to build for multiplicity |
|
|
2585 | and only include the select backend. |
|
|
2586 | |
|
|
2587 | =over 4 |
|
|
2588 | |
|
|
2589 | =item EV_STANDALONE |
|
|
2590 | |
|
|
2591 | Must always be C<1> if you do not use autoconf configuration, which |
|
|
2592 | keeps libev from including F<config.h>, and it also defines dummy |
|
|
2593 | implementations for some libevent functions (such as logging, which is not |
|
|
2594 | supported). It will also not define any of the structs usually found in |
|
|
2595 | F<event.h> that are not directly supported by the libev core alone. |
|
|
2596 | |
|
|
2597 | =item EV_USE_MONOTONIC |
|
|
2598 | |
|
|
2599 | If defined to be C<1>, libev will try to detect the availability of the |
|
|
2600 | monotonic clock option at both compiletime and runtime. Otherwise no use |
|
|
2601 | of the monotonic clock option will be attempted. If you enable this, you |
|
|
2602 | usually have to link against librt or something similar. Enabling it when |
|
|
2603 | the functionality isn't available is safe, though, although you have |
|
|
2604 | to make sure you link against any libraries where the C<clock_gettime> |
|
|
2605 | function is hiding in (often F<-lrt>). |
|
|
2606 | |
|
|
2607 | =item EV_USE_REALTIME |
|
|
2608 | |
|
|
2609 | If defined to be C<1>, libev will try to detect the availability of the |
|
|
2610 | realtime clock option at compiletime (and assume its availability at |
|
|
2611 | runtime if successful). Otherwise no use of the realtime clock option will |
|
|
2612 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
|
|
2613 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See the |
|
|
2614 | note about libraries in the description of C<EV_USE_MONOTONIC>, though. |
|
|
2615 | |
|
|
2616 | =item EV_USE_NANOSLEEP |
|
|
2617 | |
|
|
2618 | If defined to be C<1>, libev will assume that C<nanosleep ()> is available |
|
|
2619 | and will use it for delays. Otherwise it will use C<select ()>. |
|
|
2620 | |
|
|
2621 | =item EV_USE_SELECT |
|
|
2622 | |
|
|
2623 | If undefined or defined to be C<1>, libev will compile in support for the |
|
|
2624 | C<select>(2) backend. No attempt at autodetection will be done: if no |
|
|
2625 | other method takes over, select will be it. Otherwise the select backend |
|
|
2626 | will not be compiled in. |
|
|
2627 | |
|
|
2628 | =item EV_SELECT_USE_FD_SET |
|
|
2629 | |
|
|
2630 | If defined to C<1>, then the select backend will use the system C<fd_set> |
|
|
2631 | structure. This is useful if libev doesn't compile due to a missing |
|
|
2632 | C<NFDBITS> or C<fd_mask> definition or it misguesses the bitset layout on |
|
|
2633 | exotic systems. This usually limits the range of file descriptors to some |
|
|
2634 | low limit such as 1024 or might have other limitations (winsocket only |
|
|
2635 | allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might |
|
|
2636 | influence the size of the C<fd_set> used. |
|
|
2637 | |
|
|
2638 | =item EV_SELECT_IS_WINSOCKET |
|
|
2639 | |
|
|
2640 | When defined to C<1>, the select backend will assume that |
|
|
2641 | select/socket/connect etc. don't understand file descriptors but |
|
|
2642 | wants osf handles on win32 (this is the case when the select to |
|
|
2643 | be used is the winsock select). This means that it will call |
|
|
2644 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
|
|
2645 | it is assumed that all these functions actually work on fds, even |
|
|
2646 | on win32. Should not be defined on non-win32 platforms. |
|
|
2647 | |
|
|
2648 | =item EV_FD_TO_WIN32_HANDLE |
|
|
2649 | |
|
|
2650 | If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map |
|
|
2651 | file descriptors to socket handles. When not defining this symbol (the |
|
|
2652 | default), then libev will call C<_get_osfhandle>, which is usually |
|
|
2653 | correct. In some cases, programs use their own file descriptor management, |
|
|
2654 | in which case they can provide this function to map fds to socket handles. |
|
|
2655 | |
|
|
2656 | =item EV_USE_POLL |
|
|
2657 | |
|
|
2658 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
|
|
2659 | backend. Otherwise it will be enabled on non-win32 platforms. It |
|
|
2660 | takes precedence over select. |
|
|
2661 | |
|
|
2662 | =item EV_USE_EPOLL |
|
|
2663 | |
|
|
2664 | If defined to be C<1>, libev will compile in support for the Linux |
|
|
2665 | C<epoll>(7) backend. Its availability will be detected at runtime, |
|
|
2666 | otherwise another method will be used as fallback. This is the |
|
|
2667 | preferred backend for GNU/Linux systems. |
|
|
2668 | |
|
|
2669 | =item EV_USE_KQUEUE |
|
|
2670 | |
|
|
2671 | If defined to be C<1>, libev will compile in support for the BSD style |
|
|
2672 | C<kqueue>(2) backend. Its actual availability will be detected at runtime, |
|
|
2673 | otherwise another method will be used as fallback. This is the preferred |
|
|
2674 | backend for BSD and BSD-like systems, although on most BSDs kqueue only |
|
|
2675 | supports some types of fds correctly (the only platform we found that |
|
|
2676 | supports ptys for example was NetBSD), so kqueue might be compiled in, but |
|
|
2677 | not be used unless explicitly requested. The best way to use it is to find |
|
|
2678 | out whether kqueue supports your type of fd properly and use an embedded |
|
|
2679 | kqueue loop. |
|
|
2680 | |
|
|
2681 | =item EV_USE_PORT |
|
|
2682 | |
|
|
2683 | If defined to be C<1>, libev will compile in support for the Solaris |
|
|
2684 | 10 port style backend. Its availability will be detected at runtime, |
|
|
2685 | otherwise another method will be used as fallback. This is the preferred |
|
|
2686 | backend for Solaris 10 systems. |
|
|
2687 | |
|
|
2688 | =item EV_USE_DEVPOLL |
|
|
2689 | |
|
|
2690 | reserved for future expansion, works like the USE symbols above. |
|
|
2691 | |
|
|
2692 | =item EV_USE_INOTIFY |
|
|
2693 | |
|
|
2694 | If defined to be C<1>, libev will compile in support for the Linux inotify |
|
|
2695 | interface to speed up C<ev_stat> watchers. Its actual availability will |
|
|
2696 | be detected at runtime. |
|
|
2697 | |
|
|
2698 | =item EV_ATOMIC_T |
|
|
2699 | |
|
|
2700 | Libev requires an integer type (suitable for storing C<0> or C<1>) whose |
|
|
2701 | access is atomic with respect to other threads or signal contexts. No such |
|
|
2702 | type is easily found in the C language, so you can provide your own type |
|
|
2703 | that you know is safe for your purposes. It is used both for signal handler "locking" |
|
|
2704 | as well as for signal and thread safety in C<ev_async> watchers. |
|
|
2705 | |
|
|
2706 | In the absense of this define, libev will use C<sig_atomic_t volatile> |
|
|
2707 | (from F<signal.h>), which is usually good enough on most platforms. |
|
|
2708 | |
|
|
2709 | =item EV_H |
|
|
2710 | |
|
|
2711 | The name of the F<ev.h> header file used to include it. The default if |
|
|
2712 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
|
|
2713 | used to virtually rename the F<ev.h> header file in case of conflicts. |
|
|
2714 | |
|
|
2715 | =item EV_CONFIG_H |
|
|
2716 | |
|
|
2717 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
|
|
2718 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
|
|
2719 | C<EV_H>, above. |
|
|
2720 | |
|
|
2721 | =item EV_EVENT_H |
|
|
2722 | |
|
|
2723 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
|
|
2724 | of how the F<event.h> header can be found, the default is C<"event.h">. |
|
|
2725 | |
|
|
2726 | =item EV_PROTOTYPES |
|
|
2727 | |
|
|
2728 | If defined to be C<0>, then F<ev.h> will not define any function |
|
|
2729 | prototypes, but still define all the structs and other symbols. This is |
|
|
2730 | occasionally useful if you want to provide your own wrapper functions |
|
|
2731 | around libev functions. |
|
|
2732 | |
|
|
2733 | =item EV_MULTIPLICITY |
|
|
2734 | |
|
|
2735 | If undefined or defined to C<1>, then all event-loop-specific functions |
|
|
2736 | will have the C<struct ev_loop *> as first argument, and you can create |
|
|
2737 | additional independent event loops. Otherwise there will be no support |
|
|
2738 | for multiple event loops and there is no first event loop pointer |
|
|
2739 | argument. Instead, all functions act on the single default loop. |
|
|
2740 | |
|
|
2741 | =item EV_MINPRI |
|
|
2742 | |
|
|
2743 | =item EV_MAXPRI |
|
|
2744 | |
|
|
2745 | The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to |
|
|
2746 | C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can |
|
|
2747 | provide for more priorities by overriding those symbols (usually defined |
|
|
2748 | to be C<-2> and C<2>, respectively). |
|
|
2749 | |
|
|
2750 | When doing priority-based operations, libev usually has to linearly search |
|
|
2751 | all the priorities, so having many of them (hundreds) uses a lot of space |
|
|
2752 | and time, so using the defaults of five priorities (-2 .. +2) is usually |
|
|
2753 | fine. |
|
|
2754 | |
|
|
2755 | If your embedding app does not need any priorities, defining these both to |
|
|
2756 | C<0> will save some memory and cpu. |
|
|
2757 | |
|
|
2758 | =item EV_PERIODIC_ENABLE |
|
|
2759 | |
|
|
2760 | If undefined or defined to be C<1>, then periodic timers are supported. If |
|
|
2761 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
2762 | code. |
|
|
2763 | |
|
|
2764 | =item EV_IDLE_ENABLE |
|
|
2765 | |
|
|
2766 | If undefined or defined to be C<1>, then idle watchers are supported. If |
|
|
2767 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
2768 | code. |
|
|
2769 | |
|
|
2770 | =item EV_EMBED_ENABLE |
|
|
2771 | |
|
|
2772 | If undefined or defined to be C<1>, then embed watchers are supported. If |
|
|
2773 | defined to be C<0>, then they are not. |
|
|
2774 | |
|
|
2775 | =item EV_STAT_ENABLE |
|
|
2776 | |
|
|
2777 | If undefined or defined to be C<1>, then stat watchers are supported. If |
|
|
2778 | defined to be C<0>, then they are not. |
|
|
2779 | |
|
|
2780 | =item EV_FORK_ENABLE |
|
|
2781 | |
|
|
2782 | If undefined or defined to be C<1>, then fork watchers are supported. If |
|
|
2783 | defined to be C<0>, then they are not. |
|
|
2784 | |
|
|
2785 | =item EV_ASYNC_ENABLE |
|
|
2786 | |
|
|
2787 | If undefined or defined to be C<1>, then async watchers are supported. If |
|
|
2788 | defined to be C<0>, then they are not. |
|
|
2789 | |
|
|
2790 | =item EV_MINIMAL |
|
|
2791 | |
|
|
2792 | If you need to shave off some kilobytes of code at the expense of some |
|
|
2793 | speed, define this symbol to C<1>. Currently only used for gcc to override |
|
|
2794 | some inlining decisions, saves roughly 30% codesize of amd64. |
|
|
2795 | |
|
|
2796 | =item EV_PID_HASHSIZE |
|
|
2797 | |
|
|
2798 | C<ev_child> watchers use a small hash table to distribute workload by |
|
|
2799 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
|
|
2800 | than enough. If you need to manage thousands of children you might want to |
|
|
2801 | increase this value (I<must> be a power of two). |
|
|
2802 | |
|
|
2803 | =item EV_INOTIFY_HASHSIZE |
|
|
2804 | |
|
|
2805 | C<ev_stat> watchers use a small hash table to distribute workload by |
|
|
2806 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
|
|
2807 | usually more than enough. If you need to manage thousands of C<ev_stat> |
|
|
2808 | watchers you might want to increase this value (I<must> be a power of |
|
|
2809 | two). |
|
|
2810 | |
|
|
2811 | =item EV_COMMON |
|
|
2812 | |
|
|
2813 | By default, all watchers have a C<void *data> member. By redefining |
|
|
2814 | this macro to a something else you can include more and other types of |
|
|
2815 | members. You have to define it each time you include one of the files, |
|
|
2816 | though, and it must be identical each time. |
|
|
2817 | |
|
|
2818 | For example, the perl EV module uses something like this: |
|
|
2819 | |
|
|
2820 | #define EV_COMMON \ |
|
|
2821 | SV *self; /* contains this struct */ \ |
|
|
2822 | SV *cb_sv, *fh /* note no trailing ";" */ |
|
|
2823 | |
|
|
2824 | =item EV_CB_DECLARE (type) |
|
|
2825 | |
|
|
2826 | =item EV_CB_INVOKE (watcher, revents) |
|
|
2827 | |
|
|
2828 | =item ev_set_cb (ev, cb) |
|
|
2829 | |
|
|
2830 | Can be used to change the callback member declaration in each watcher, |
|
|
2831 | and the way callbacks are invoked and set. Must expand to a struct member |
|
|
2832 | definition and a statement, respectively. See the F<ev.h> header file for |
|
|
2833 | their default definitions. One possible use for overriding these is to |
|
|
2834 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
|
|
2835 | method calls instead of plain function calls in C++. |
|
|
2836 | |
|
|
2837 | =head2 EXPORTED API SYMBOLS |
|
|
2838 | |
|
|
2839 | If you need to re-export the API (e.g. via a dll) and you need a list of |
|
|
2840 | exported symbols, you can use the provided F<Symbol.*> files which list |
|
|
2841 | all public symbols, one per line: |
|
|
2842 | |
|
|
2843 | Symbols.ev for libev proper |
|
|
2844 | Symbols.event for the libevent emulation |
|
|
2845 | |
|
|
2846 | This can also be used to rename all public symbols to avoid clashes with |
|
|
2847 | multiple versions of libev linked together (which is obviously bad in |
|
|
2848 | itself, but sometimes it is inconvinient to avoid this). |
|
|
2849 | |
|
|
2850 | A sed command like this will create wrapper C<#define>'s that you need to |
|
|
2851 | include before including F<ev.h>: |
|
|
2852 | |
|
|
2853 | <Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h |
|
|
2854 | |
|
|
2855 | This would create a file F<wrap.h> which essentially looks like this: |
|
|
2856 | |
|
|
2857 | #define ev_backend myprefix_ev_backend |
|
|
2858 | #define ev_check_start myprefix_ev_check_start |
|
|
2859 | #define ev_check_stop myprefix_ev_check_stop |
|
|
2860 | ... |
|
|
2861 | |
|
|
2862 | =head2 EXAMPLES |
|
|
2863 | |
|
|
2864 | For a real-world example of a program the includes libev |
|
|
2865 | verbatim, you can have a look at the EV perl module |
|
|
2866 | (L<http://software.schmorp.de/pkg/EV.html>). It has the libev files in |
|
|
2867 | the F<libev/> subdirectory and includes them in the F<EV/EVAPI.h> (public |
|
|
2868 | interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file |
|
|
2869 | will be compiled. It is pretty complex because it provides its own header |
|
|
2870 | file. |
|
|
2871 | |
|
|
2872 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
|
|
2873 | that everybody includes and which overrides some configure choices: |
|
|
2874 | |
|
|
2875 | #define EV_MINIMAL 1 |
|
|
2876 | #define EV_USE_POLL 0 |
|
|
2877 | #define EV_MULTIPLICITY 0 |
|
|
2878 | #define EV_PERIODIC_ENABLE 0 |
|
|
2879 | #define EV_STAT_ENABLE 0 |
|
|
2880 | #define EV_FORK_ENABLE 0 |
|
|
2881 | #define EV_CONFIG_H <config.h> |
|
|
2882 | #define EV_MINPRI 0 |
|
|
2883 | #define EV_MAXPRI 0 |
|
|
2884 | |
|
|
2885 | #include "ev++.h" |
|
|
2886 | |
|
|
2887 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
|
|
2888 | |
|
|
2889 | #include "ev_cpp.h" |
|
|
2890 | #include "ev.c" |
|
|
2891 | |
|
|
2892 | |
|
|
2893 | =head1 COMPLEXITIES |
|
|
2894 | |
|
|
2895 | In this section the complexities of (many of) the algorithms used inside |
|
|
2896 | libev will be explained. For complexity discussions about backends see the |
|
|
2897 | documentation for C<ev_default_init>. |
|
|
2898 | |
|
|
2899 | All of the following are about amortised time: If an array needs to be |
|
|
2900 | extended, libev needs to realloc and move the whole array, but this |
|
|
2901 | happens asymptotically never with higher number of elements, so O(1) might |
|
|
2902 | mean it might do a lengthy realloc operation in rare cases, but on average |
|
|
2903 | it is much faster and asymptotically approaches constant time. |
|
|
2904 | |
|
|
2905 | =over 4 |
|
|
2906 | |
|
|
2907 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
|
|
2908 | |
|
|
2909 | This means that, when you have a watcher that triggers in one hour and |
|
|
2910 | there are 100 watchers that would trigger before that then inserting will |
|
|
2911 | have to skip roughly seven (C<ld 100>) of these watchers. |
|
|
2912 | |
|
|
2913 | =item Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers) |
|
|
2914 | |
|
|
2915 | That means that changing a timer costs less than removing/adding them |
|
|
2916 | as only the relative motion in the event queue has to be paid for. |
|
|
2917 | |
|
|
2918 | =item Starting io/check/prepare/idle/signal/child/fork/async watchers: O(1) |
|
|
2919 | |
|
|
2920 | These just add the watcher into an array or at the head of a list. |
|
|
2921 | |
|
|
2922 | =item Stopping check/prepare/idle/fork/async watchers: O(1) |
|
|
2923 | |
|
|
2924 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
|
|
2925 | |
|
|
2926 | These watchers are stored in lists then need to be walked to find the |
|
|
2927 | correct watcher to remove. The lists are usually short (you don't usually |
|
|
2928 | have many watchers waiting for the same fd or signal). |
|
|
2929 | |
|
|
2930 | =item Finding the next timer in each loop iteration: O(1) |
|
|
2931 | |
|
|
2932 | By virtue of using a binary heap, the next timer is always found at the |
|
|
2933 | beginning of the storage array. |
|
|
2934 | |
|
|
2935 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
|
|
2936 | |
|
|
2937 | A change means an I/O watcher gets started or stopped, which requires |
|
|
2938 | libev to recalculate its status (and possibly tell the kernel, depending |
|
|
2939 | on backend and wether C<ev_io_set> was used). |
|
|
2940 | |
|
|
2941 | =item Activating one watcher (putting it into the pending state): O(1) |
|
|
2942 | |
|
|
2943 | =item Priority handling: O(number_of_priorities) |
|
|
2944 | |
|
|
2945 | Priorities are implemented by allocating some space for each |
|
|
2946 | priority. When doing priority-based operations, libev usually has to |
|
|
2947 | linearly search all the priorities, but starting/stopping and activating |
|
|
2948 | watchers becomes O(1) w.r.t. priority handling. |
|
|
2949 | |
|
|
2950 | =item Sending an ev_async: O(1) |
|
|
2951 | |
|
|
2952 | =item Processing ev_async_send: O(number_of_async_watchers) |
|
|
2953 | |
|
|
2954 | =item Processing signals: O(max_signal_number) |
|
|
2955 | |
|
|
2956 | Sending involves a syscall I<iff> there were no other C<ev_async_send> |
|
|
2957 | calls in the current loop iteration. Checking for async and signal events |
|
|
2958 | involves iterating over all running async watchers or all signal numbers. |
|
|
2959 | |
|
|
2960 | =back |
|
|
2961 | |
|
|
2962 | |
|
|
2963 | =head1 Win32 platform limitations and workarounds |
|
|
2964 | |
|
|
2965 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
|
|
2966 | requires, and its I/O model is fundamentally incompatible with the POSIX |
|
|
2967 | model. Libev still offers limited functionality on this platform in |
|
|
2968 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
|
|
2969 | descriptors. This only applies when using Win32 natively, not when using |
|
|
2970 | e.g. cygwin. |
|
|
2971 | |
|
|
2972 | There is no supported compilation method available on windows except |
|
|
2973 | embedding it into other applications. |
|
|
2974 | |
|
|
2975 | Due to the many, low, and arbitrary limits on the win32 platform and the |
|
|
2976 | abysmal performance of winsockets, using a large number of sockets is not |
|
|
2977 | recommended (and not reasonable). If your program needs to use more than |
|
|
2978 | a hundred or so sockets, then likely it needs to use a totally different |
|
|
2979 | implementation for windows, as libev offers the POSIX model, which cannot |
|
|
2980 | be implemented efficiently on windows (microsoft monopoly games). |
|
|
2981 | |
|
|
2982 | =over 4 |
|
|
2983 | |
|
|
2984 | =item The winsocket select function |
|
|
2985 | |
|
|
2986 | The winsocket C<select> function doesn't follow POSIX in that it requires |
|
|
2987 | socket I<handles> and not socket I<file descriptors>. This makes select |
|
|
2988 | very inefficient, and also requires a mapping from file descriptors |
|
|
2989 | to socket handles. See the discussion of the C<EV_SELECT_USE_FD_SET>, |
|
|
2990 | C<EV_SELECT_IS_WINSOCKET> and C<EV_FD_TO_WIN32_HANDLE> preprocessor |
|
|
2991 | symbols for more info. |
|
|
2992 | |
|
|
2993 | The configuration for a "naked" win32 using the microsoft runtime |
|
|
2994 | libraries and raw winsocket select is: |
|
|
2995 | |
|
|
2996 | #define EV_USE_SELECT 1 |
|
|
2997 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
|
|
2998 | |
|
|
2999 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
|
|
3000 | complexity in the O(n²) range when using win32. |
|
|
3001 | |
|
|
3002 | =item Limited number of file descriptors |
|
|
3003 | |
|
|
3004 | Windows has numerous arbitrary (and low) limits on things. Early versions |
|
|
3005 | of winsocket's select only supported waiting for a max. of C<64> handles |
|
|
3006 | (probably owning to the fact that all windows kernels can only wait for |
|
|
3007 | C<64> things at the same time internally; microsoft recommends spawning a |
|
|
3008 | chain of threads and wait for 63 handles and the previous thread in each). |
|
|
3009 | |
|
|
3010 | Newer versions support more handles, but you need to define C<FD_SETSIZE> |
|
|
3011 | to some high number (e.g. C<2048>) before compiling the winsocket select |
|
|
3012 | call (which might be in libev or elsewhere, for example, perl does its own |
|
|
3013 | select emulation on windows). |
|
|
3014 | |
|
|
3015 | Another limit is the number of file descriptors in the microsoft runtime |
|
|
3016 | libraries, which by default is C<64> (there must be a hidden I<64> fetish |
|
|
3017 | or something like this inside microsoft). You can increase this by calling |
|
|
3018 | C<_setmaxstdio>, which can increase this limit to C<2048> (another |
|
|
3019 | arbitrary limit), but is broken in many versions of the microsoft runtime |
|
|
3020 | libraries. |
|
|
3021 | |
|
|
3022 | This might get you to about C<512> or C<2048> sockets (depending on |
|
|
3023 | windows version and/or the phase of the moon). To get more, you need to |
|
|
3024 | wrap all I/O functions and provide your own fd management, but the cost of |
|
|
3025 | calling select (O(n²)) will likely make this unworkable. |
|
|
3026 | |
|
|
3027 | =back |
|
|
3028 | |
|
|
3029 | |
767 | =head1 AUTHOR |
3030 | =head1 AUTHOR |
768 | |
3031 | |
769 | Marc Lehmann <libev@schmorp.de>. |
3032 | Marc Lehmann <libev@schmorp.de>. |
770 | |
3033 | |