… | |
… | |
118 | Libev is very configurable. In this manual the default (and most common) |
118 | Libev is very configurable. In this manual the default (and most common) |
119 | configuration will be described, which supports multiple event loops. For |
119 | configuration will be described, which supports multiple event loops. For |
120 | more info about various configuration options please have a look at |
120 | more info about various configuration options please have a look at |
121 | B<EMBED> section in this manual. If libev was configured without support |
121 | B<EMBED> section in this manual. If libev was configured without support |
122 | for multiple event loops, then all functions taking an initial argument of |
122 | for multiple event loops, then all functions taking an initial argument of |
123 | name C<loop> (which is always of type C<ev_loop *>) will not have |
123 | name C<loop> (which is always of type C<struct ev_loop *>) will not have |
124 | this argument. |
124 | this argument. |
125 | |
125 | |
126 | =head2 TIME REPRESENTATION |
126 | =head2 TIME REPRESENTATION |
127 | |
127 | |
128 | Libev represents time as a single floating point number, representing |
128 | Libev represents time as a single floating point number, representing |
… | |
… | |
370 | When this flag is specified, then libev will not attempt to use the |
370 | When this flag is specified, then libev will not attempt to use the |
371 | I<inotify> API for it's C<ev_stat> watchers. Apart from debugging and |
371 | I<inotify> API for it's C<ev_stat> watchers. Apart from debugging and |
372 | testing, this flag can be useful to conserve inotify file descriptors, as |
372 | testing, this flag can be useful to conserve inotify file descriptors, as |
373 | otherwise each loop using C<ev_stat> watchers consumes one inotify handle. |
373 | otherwise each loop using C<ev_stat> watchers consumes one inotify handle. |
374 | |
374 | |
375 | =item C<EVFLAG_NOSIGNALFD> |
375 | =item C<EVFLAG_NOSIGFD> |
376 | |
376 | |
377 | When this flag is specified, then libev will not attempt to use the |
377 | When this flag is specified, then libev will not attempt to use the |
378 | I<signalfd> API for it's C<ev_signal> (and C<ev_child>) watchers. This is |
378 | I<signalfd> API for it's C<ev_signal> (and C<ev_child>) watchers. This is |
379 | probably only useful to work around any bugs in libev. Consequently, this |
379 | probably only useful to work around any bugs in libev. Consequently, this |
380 | flag might go away once the signalfd functionality is considered stable, |
380 | flag might go away once the signalfd functionality is considered stable, |
… | |
… | |
410 | |
410 | |
411 | This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and |
411 | This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and |
412 | C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>. |
412 | C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>. |
413 | |
413 | |
414 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
414 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
|
|
415 | |
|
|
416 | Use the linux-specific epoll(7) interface (for both pre- and post-2.6.9 |
|
|
417 | kernels). |
415 | |
418 | |
416 | For few fds, this backend is a bit little slower than poll and select, |
419 | For few fds, this backend is a bit little slower than poll and select, |
417 | but it scales phenomenally better. While poll and select usually scale |
420 | but it scales phenomenally better. While poll and select usually scale |
418 | like O(total_fds) where n is the total number of fds (or the highest fd), |
421 | like O(total_fds) where n is the total number of fds (or the highest fd), |
419 | epoll scales either O(1) or O(active_fds). |
422 | epoll scales either O(1) or O(active_fds). |
… | |
… | |
590 | as signal and child watchers) would need to be stopped manually. |
593 | as signal and child watchers) would need to be stopped manually. |
591 | |
594 | |
592 | In general it is not advisable to call this function except in the |
595 | In general it is not advisable to call this function except in the |
593 | rare occasion where you really need to free e.g. the signal handling |
596 | rare occasion where you really need to free e.g. the signal handling |
594 | pipe fds. If you need dynamically allocated loops it is better to use |
597 | pipe fds. If you need dynamically allocated loops it is better to use |
595 | C<ev_loop_new> and C<ev_loop_destroy>). |
598 | C<ev_loop_new> and C<ev_loop_destroy>. |
596 | |
599 | |
597 | =item ev_loop_destroy (loop) |
600 | =item ev_loop_destroy (loop) |
598 | |
601 | |
599 | Like C<ev_default_destroy>, but destroys an event loop created by an |
602 | Like C<ev_default_destroy>, but destroys an event loop created by an |
600 | earlier call to C<ev_loop_new>. |
603 | earlier call to C<ev_loop_new>. |
… | |
… | |
704 | event loop time (see C<ev_now_update>). |
707 | event loop time (see C<ev_now_update>). |
705 | |
708 | |
706 | =item ev_loop (loop, int flags) |
709 | =item ev_loop (loop, int flags) |
707 | |
710 | |
708 | Finally, this is it, the event handler. This function usually is called |
711 | Finally, this is it, the event handler. This function usually is called |
709 | after you initialised all your watchers and you want to start handling |
712 | after you have initialised all your watchers and you want to start |
710 | events. |
713 | handling events. |
711 | |
714 | |
712 | If the flags argument is specified as C<0>, it will not return until |
715 | If the flags argument is specified as C<0>, it will not return until |
713 | either no event watchers are active anymore or C<ev_unloop> was called. |
716 | either no event watchers are active anymore or C<ev_unloop> was called. |
714 | |
717 | |
715 | Please note that an explicit C<ev_unloop> is usually better than |
718 | Please note that an explicit C<ev_unloop> is usually better than |
… | |
… | |
916 | |
919 | |
917 | While event loop modifications are allowed between invocations of |
920 | While event loop modifications are allowed between invocations of |
918 | C<release> and C<acquire> (that's their only purpose after all), no |
921 | C<release> and C<acquire> (that's their only purpose after all), no |
919 | modifications done will affect the event loop, i.e. adding watchers will |
922 | modifications done will affect the event loop, i.e. adding watchers will |
920 | have no effect on the set of file descriptors being watched, or the time |
923 | have no effect on the set of file descriptors being watched, or the time |
921 | waited. USe an C<ev_async> watcher to wake up C<ev_loop> when you want it |
924 | waited. Use an C<ev_async> watcher to wake up C<ev_loop> when you want it |
922 | to take note of any changes you made. |
925 | to take note of any changes you made. |
923 | |
926 | |
924 | In theory, threads executing C<ev_loop> will be async-cancel safe between |
927 | In theory, threads executing C<ev_loop> will be async-cancel safe between |
925 | invocations of C<release> and C<acquire>. |
928 | invocations of C<release> and C<acquire>. |
926 | |
929 | |
… | |
… | |
1123 | |
1126 | |
1124 | ev_io w; |
1127 | ev_io w; |
1125 | ev_init (&w, my_cb); |
1128 | ev_init (&w, my_cb); |
1126 | ev_io_set (&w, STDIN_FILENO, EV_READ); |
1129 | ev_io_set (&w, STDIN_FILENO, EV_READ); |
1127 | |
1130 | |
1128 | =item C<ev_TYPE_set> (ev_TYPE *, [args]) |
1131 | =item C<ev_TYPE_set> (ev_TYPE *watcher, [args]) |
1129 | |
1132 | |
1130 | This macro initialises the type-specific parts of a watcher. You need to |
1133 | This macro initialises the type-specific parts of a watcher. You need to |
1131 | call C<ev_init> at least once before you call this macro, but you can |
1134 | call C<ev_init> at least once before you call this macro, but you can |
1132 | call C<ev_TYPE_set> any number of times. You must not, however, call this |
1135 | call C<ev_TYPE_set> any number of times. You must not, however, call this |
1133 | macro on a watcher that is active (it can be pending, however, which is a |
1136 | macro on a watcher that is active (it can be pending, however, which is a |
… | |
… | |
1146 | |
1149 | |
1147 | Example: Initialise and set an C<ev_io> watcher in one step. |
1150 | Example: Initialise and set an C<ev_io> watcher in one step. |
1148 | |
1151 | |
1149 | ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
1152 | ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
1150 | |
1153 | |
1151 | =item C<ev_TYPE_start> (loop *, ev_TYPE *watcher) |
1154 | =item C<ev_TYPE_start> (loop, ev_TYPE *watcher) |
1152 | |
1155 | |
1153 | Starts (activates) the given watcher. Only active watchers will receive |
1156 | Starts (activates) the given watcher. Only active watchers will receive |
1154 | events. If the watcher is already active nothing will happen. |
1157 | events. If the watcher is already active nothing will happen. |
1155 | |
1158 | |
1156 | Example: Start the C<ev_io> watcher that is being abused as example in this |
1159 | Example: Start the C<ev_io> watcher that is being abused as example in this |
1157 | whole section. |
1160 | whole section. |
1158 | |
1161 | |
1159 | ev_io_start (EV_DEFAULT_UC, &w); |
1162 | ev_io_start (EV_DEFAULT_UC, &w); |
1160 | |
1163 | |
1161 | =item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher) |
1164 | =item C<ev_TYPE_stop> (loop, ev_TYPE *watcher) |
1162 | |
1165 | |
1163 | Stops the given watcher if active, and clears the pending status (whether |
1166 | Stops the given watcher if active, and clears the pending status (whether |
1164 | the watcher was active or not). |
1167 | the watcher was active or not). |
1165 | |
1168 | |
1166 | It is possible that stopped watchers are pending - for example, |
1169 | It is possible that stopped watchers are pending - for example, |
… | |
… | |
1191 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1194 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1192 | |
1195 | |
1193 | Change the callback. You can change the callback at virtually any time |
1196 | Change the callback. You can change the callback at virtually any time |
1194 | (modulo threads). |
1197 | (modulo threads). |
1195 | |
1198 | |
1196 | =item ev_set_priority (ev_TYPE *watcher, priority) |
1199 | =item ev_set_priority (ev_TYPE *watcher, int priority) |
1197 | |
1200 | |
1198 | =item int ev_priority (ev_TYPE *watcher) |
1201 | =item int ev_priority (ev_TYPE *watcher) |
1199 | |
1202 | |
1200 | Set and query the priority of the watcher. The priority is a small |
1203 | Set and query the priority of the watcher. The priority is a small |
1201 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
1204 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
… | |
… | |
1232 | returns its C<revents> bitset (as if its callback was invoked). If the |
1235 | returns its C<revents> bitset (as if its callback was invoked). If the |
1233 | watcher isn't pending it does nothing and returns C<0>. |
1236 | watcher isn't pending it does nothing and returns C<0>. |
1234 | |
1237 | |
1235 | Sometimes it can be useful to "poll" a watcher instead of waiting for its |
1238 | Sometimes it can be useful to "poll" a watcher instead of waiting for its |
1236 | callback to be invoked, which can be accomplished with this function. |
1239 | callback to be invoked, which can be accomplished with this function. |
|
|
1240 | |
|
|
1241 | =item ev_feed_event (loop, ev_TYPE *watcher, int revents) |
|
|
1242 | |
|
|
1243 | Feeds the given event set into the event loop, as if the specified event |
|
|
1244 | had happened for the specified watcher (which must be a pointer to an |
|
|
1245 | initialised but not necessarily started event watcher). Obviously you must |
|
|
1246 | not free the watcher as long as it has pending events. |
|
|
1247 | |
|
|
1248 | Stopping the watcher, letting libev invoke it, or calling |
|
|
1249 | C<ev_clear_pending> will clear the pending event, even if the watcher was |
|
|
1250 | not started in the first place. |
|
|
1251 | |
|
|
1252 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
|
|
1253 | functions that do not need a watcher. |
1237 | |
1254 | |
1238 | =back |
1255 | =back |
1239 | |
1256 | |
1240 | |
1257 | |
1241 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
1258 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
… | |
… | |
2108 | |
2125 | |
2109 | When the first watcher gets started will libev actually register something |
2126 | When the first watcher gets started will libev actually register something |
2110 | with the kernel (thus it coexists with your own signal handlers as long as |
2127 | with the kernel (thus it coexists with your own signal handlers as long as |
2111 | you don't register any with libev for the same signal). |
2128 | you don't register any with libev for the same signal). |
2112 | |
2129 | |
2113 | Both the signal mask state (C<sigprocmask>) and the signal handler state |
|
|
2114 | (C<sigaction>) are unspecified after starting a signal watcher (and after |
|
|
2115 | sotpping it again), that is, libev might or might not block the signal, |
|
|
2116 | and might or might not set or restore the installed signal handler. |
|
|
2117 | |
|
|
2118 | If possible and supported, libev will install its handlers with |
2130 | If possible and supported, libev will install its handlers with |
2119 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2131 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2120 | not be unduly interrupted. If you have a problem with system calls getting |
2132 | not be unduly interrupted. If you have a problem with system calls getting |
2121 | interrupted by signals you can block all signals in an C<ev_check> watcher |
2133 | interrupted by signals you can block all signals in an C<ev_check> watcher |
2122 | and unblock them in an C<ev_prepare> watcher. |
2134 | and unblock them in an C<ev_prepare> watcher. |
|
|
2135 | |
|
|
2136 | =head3 The special problem of inheritance over execve |
|
|
2137 | |
|
|
2138 | Both the signal mask (C<sigprocmask>) and the signal disposition |
|
|
2139 | (C<sigaction>) are unspecified after starting a signal watcher (and after |
|
|
2140 | stopping it again), that is, libev might or might not block the signal, |
|
|
2141 | and might or might not set or restore the installed signal handler. |
|
|
2142 | |
|
|
2143 | While this does not matter for the signal disposition (libev never |
|
|
2144 | sets signals to C<SIG_IGN>, so handlers will be reset to C<SIG_DFL> on |
|
|
2145 | C<execve>), this matters for the signal mask: many programs do not expect |
|
|
2146 | certain signals to be blocked. |
|
|
2147 | |
|
|
2148 | This means that before calling C<exec> (from the child) you should reset |
|
|
2149 | the signal mask to whatever "default" you expect (all clear is a good |
|
|
2150 | choice usually). |
|
|
2151 | |
|
|
2152 | The simplest way to ensure that the signal mask is reset in the child is |
|
|
2153 | to install a fork handler with C<pthread_atfork> that resets it. That will |
|
|
2154 | catch fork calls done by libraries (such as the libc) as well. |
|
|
2155 | |
|
|
2156 | In current versions of libev, you can also ensure that the signal mask is |
|
|
2157 | not blocking any signals (except temporarily, so thread users watch out) |
|
|
2158 | by specifying the C<EVFLAG_NOSIGFD> when creating the event loop. This |
|
|
2159 | is not guaranteed for future versions, however. |
2123 | |
2160 | |
2124 | =head3 Watcher-Specific Functions and Data Members |
2161 | =head3 Watcher-Specific Functions and Data Members |
2125 | |
2162 | |
2126 | =over 4 |
2163 | =over 4 |
2127 | |
2164 | |
… | |
… | |
2944 | =head3 Queueing |
2981 | =head3 Queueing |
2945 | |
2982 | |
2946 | C<ev_async> does not support queueing of data in any way. The reason |
2983 | C<ev_async> does not support queueing of data in any way. The reason |
2947 | is that the author does not know of a simple (or any) algorithm for a |
2984 | is that the author does not know of a simple (or any) algorithm for a |
2948 | multiple-writer-single-reader queue that works in all cases and doesn't |
2985 | multiple-writer-single-reader queue that works in all cases and doesn't |
2949 | need elaborate support such as pthreads. |
2986 | need elaborate support such as pthreads or unportable memory access |
|
|
2987 | semantics. |
2950 | |
2988 | |
2951 | That means that if you want to queue data, you have to provide your own |
2989 | That means that if you want to queue data, you have to provide your own |
2952 | queue. But at least I can tell you how to implement locking around your |
2990 | queue. But at least I can tell you how to implement locking around your |
2953 | queue: |
2991 | queue: |
2954 | |
2992 | |
… | |
… | |
3112 | /* doh, nothing entered */; |
3150 | /* doh, nothing entered */; |
3113 | } |
3151 | } |
3114 | |
3152 | |
3115 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3153 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3116 | |
3154 | |
3117 | =item ev_feed_event (struct ev_loop *, watcher *, int revents) |
|
|
3118 | |
|
|
3119 | Feeds the given event set into the event loop, as if the specified event |
|
|
3120 | had happened for the specified watcher (which must be a pointer to an |
|
|
3121 | initialised but not necessarily started event watcher). |
|
|
3122 | |
|
|
3123 | =item ev_feed_fd_event (struct ev_loop *, int fd, int revents) |
3155 | =item ev_feed_fd_event (loop, int fd, int revents) |
3124 | |
3156 | |
3125 | Feed an event on the given fd, as if a file descriptor backend detected |
3157 | Feed an event on the given fd, as if a file descriptor backend detected |
3126 | the given events it. |
3158 | the given events it. |
3127 | |
3159 | |
3128 | =item ev_feed_signal_event (struct ev_loop *loop, int signum) |
3160 | =item ev_feed_signal_event (loop, int signum) |
3129 | |
3161 | |
3130 | Feed an event as if the given signal occurred (C<loop> must be the default |
3162 | Feed an event as if the given signal occurred (C<loop> must be the default |
3131 | loop!). |
3163 | loop!). |
3132 | |
3164 | |
3133 | =back |
3165 | =back |
… | |
… | |
3213 | |
3245 | |
3214 | =over 4 |
3246 | =over 4 |
3215 | |
3247 | |
3216 | =item ev::TYPE::TYPE () |
3248 | =item ev::TYPE::TYPE () |
3217 | |
3249 | |
3218 | =item ev::TYPE::TYPE (struct ev_loop *) |
3250 | =item ev::TYPE::TYPE (loop) |
3219 | |
3251 | |
3220 | =item ev::TYPE::~TYPE |
3252 | =item ev::TYPE::~TYPE |
3221 | |
3253 | |
3222 | The constructor (optionally) takes an event loop to associate the watcher |
3254 | The constructor (optionally) takes an event loop to associate the watcher |
3223 | with. If it is omitted, it will use C<EV_DEFAULT>. |
3255 | with. If it is omitted, it will use C<EV_DEFAULT>. |
… | |
… | |
3300 | Example: Use a plain function as callback. |
3332 | Example: Use a plain function as callback. |
3301 | |
3333 | |
3302 | static void io_cb (ev::io &w, int revents) { } |
3334 | static void io_cb (ev::io &w, int revents) { } |
3303 | iow.set <io_cb> (); |
3335 | iow.set <io_cb> (); |
3304 | |
3336 | |
3305 | =item w->set (struct ev_loop *) |
3337 | =item w->set (loop) |
3306 | |
3338 | |
3307 | Associates a different C<struct ev_loop> with this watcher. You can only |
3339 | Associates a different C<struct ev_loop> with this watcher. You can only |
3308 | do this when the watcher is inactive (and not pending either). |
3340 | do this when the watcher is inactive (and not pending either). |
3309 | |
3341 | |
3310 | =item w->set ([arguments]) |
3342 | =item w->set ([arguments]) |