… | |
… | |
260 | flags. If that is troubling you, check C<ev_backend ()> afterwards). |
260 | flags. If that is troubling you, check C<ev_backend ()> afterwards). |
261 | |
261 | |
262 | 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 |
263 | function. |
263 | function. |
264 | |
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 | |
265 | 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 |
266 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
273 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
267 | |
274 | |
268 | The following flags are supported: |
275 | The following flags are supported: |
269 | |
276 | |
… | |
… | |
476 | 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 |
477 | earlier call to C<ev_loop_new>. |
484 | earlier call to C<ev_loop_new>. |
478 | |
485 | |
479 | =item ev_default_fork () |
486 | =item ev_default_fork () |
480 | |
487 | |
|
|
488 | This function sets a flag that causes subsequent C<ev_loop> iterations |
481 | This function reinitialises the kernel state for backends that have |
489 | to reinitialise the kernel state for backends that have one. Despite the |
482 | 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 |
483 | 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 |
484 | 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. |
485 | |
494 | |
486 | You I<must> call this function in the child process after forking if and |
495 | On the other hand, you only need to call this function in the child |
487 | only if you want to use the event library in both processes. If you just |
496 | process if and only if you want to use the event library in the child. If |
488 | fork+exec, you don't have to call it. |
497 | you just fork+exec, you don't have to call it at all. |
489 | |
498 | |
490 | 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 |
491 | 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 |
492 | quite nicely into a call to C<pthread_atfork>: |
501 | quite nicely into a call to C<pthread_atfork>: |
493 | |
502 | |
494 | pthread_atfork (0, 0, ev_default_fork); |
503 | pthread_atfork (0, 0, ev_default_fork); |
495 | |
|
|
496 | At the moment, C<EVBACKEND_SELECT> and C<EVBACKEND_POLL> are safe to use |
|
|
497 | without calling this function, so if you force one of those backends you |
|
|
498 | do not need to care. |
|
|
499 | |
504 | |
500 | =item ev_loop_fork (loop) |
505 | =item ev_loop_fork (loop) |
501 | |
506 | |
502 | 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 |
503 | 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 |
… | |
… | |
769 | =item C<EV_FORK> |
774 | =item C<EV_FORK> |
770 | |
775 | |
771 | The event loop has been resumed in the child process after fork (see |
776 | The event loop has been resumed in the child process after fork (see |
772 | C<ev_fork>). |
777 | C<ev_fork>). |
773 | |
778 | |
|
|
779 | =item C<EV_ASYNC> |
|
|
780 | |
|
|
781 | The given async watcher has been asynchronously notified (see C<ev_async>). |
|
|
782 | |
774 | =item C<EV_ERROR> |
783 | =item C<EV_ERROR> |
775 | |
784 | |
776 | 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 |
777 | happen because the watcher could not be properly started because libev |
786 | happen because the watcher could not be properly started because libev |
778 | 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 |
… | |
… | |
1433 | |
1442 | |
1434 | =head3 Watcher-Specific Functions and Data Members |
1443 | =head3 Watcher-Specific Functions and Data Members |
1435 | |
1444 | |
1436 | =over 4 |
1445 | =over 4 |
1437 | |
1446 | |
1438 | =item ev_child_init (ev_child *, callback, int pid) |
1447 | =item ev_child_init (ev_child *, callback, int pid, int trace) |
1439 | |
1448 | |
1440 | =item ev_child_set (ev_child *, int pid) |
1449 | =item ev_child_set (ev_child *, int pid, int trace) |
1441 | |
1450 | |
1442 | 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 |
1443 | 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 |
1444 | 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 |
1445 | 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 |
1446 | 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 |
1447 | 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). |
1448 | |
1459 | |
1449 | =item int pid [read-only] |
1460 | =item int pid [read-only] |
1450 | |
1461 | |
1451 | The process id this watcher watches out for, or C<0>, meaning any process id. |
1462 | The process id this watcher watches out for, or C<0>, meaning any process id. |
1452 | |
1463 | |
… | |
… | |
1688 | static void |
1699 | static void |
1689 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1700 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1690 | { |
1701 | { |
1691 | free (w); |
1702 | free (w); |
1692 | // now do something you wanted to do when the program has |
1703 | // now do something you wanted to do when the program has |
1693 | // no longer asnything immediate to do. |
1704 | // no longer anything immediate to do. |
1694 | } |
1705 | } |
1695 | |
1706 | |
1696 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1707 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1697 | ev_idle_init (idle_watcher, idle_cb); |
1708 | ev_idle_init (idle_watcher, idle_cb); |
1698 | ev_idle_start (loop, idle_cb); |
1709 | ev_idle_start (loop, idle_cb); |
… | |
… | |
2039 | believe me. |
2050 | believe me. |
2040 | |
2051 | |
2041 | =back |
2052 | =back |
2042 | |
2053 | |
2043 | |
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. And here is how you would implement locking: |
|
|
2084 | |
|
|
2085 | =over 4 |
|
|
2086 | |
|
|
2087 | =item queueing from a signal handler context |
|
|
2088 | |
|
|
2089 | To implement race-free queueing, you simply add to the queue in the signal |
|
|
2090 | handler but you block the signal handler in the watcher callback. Here is an example that does that for |
|
|
2091 | some fictitiuous SIGUSR1 handler: |
|
|
2092 | |
|
|
2093 | static ev_async mysig; |
|
|
2094 | |
|
|
2095 | static void |
|
|
2096 | sigusr1_handler (void) |
|
|
2097 | { |
|
|
2098 | sometype data; |
|
|
2099 | |
|
|
2100 | // no locking etc. |
|
|
2101 | queue_put (data); |
|
|
2102 | ev_async_send (DEFAULT_ &mysig); |
|
|
2103 | } |
|
|
2104 | |
|
|
2105 | static void |
|
|
2106 | mysig_cb (EV_P_ ev_async *w, int revents) |
|
|
2107 | { |
|
|
2108 | sometype data; |
|
|
2109 | sigset_t block, prev; |
|
|
2110 | |
|
|
2111 | sigemptyset (&block); |
|
|
2112 | sigaddset (&block, SIGUSR1); |
|
|
2113 | sigprocmask (SIG_BLOCK, &block, &prev); |
|
|
2114 | |
|
|
2115 | while (queue_get (&data)) |
|
|
2116 | process (data); |
|
|
2117 | |
|
|
2118 | if (sigismember (&prev, SIGUSR1) |
|
|
2119 | sigprocmask (SIG_UNBLOCK, &block, 0); |
|
|
2120 | } |
|
|
2121 | |
|
|
2122 | (Note: pthreads in theory requires you to use C<pthread_setmask> |
|
|
2123 | instead of C<sigprocmask> when you use threads, but libev doesn't do it |
|
|
2124 | either...). |
|
|
2125 | |
|
|
2126 | =item queueing from a thread context |
|
|
2127 | |
|
|
2128 | The strategy for threads is different, as you cannot (easily) block |
|
|
2129 | threads but you can easily preempt them, so to queue safely you need to |
|
|
2130 | emply a traditional mutex lock, such as in this pthread example: |
|
|
2131 | |
|
|
2132 | static ev_async mysig; |
|
|
2133 | static pthread_mutex_t mymutex = PTHREAD_MUTEX_INITIALIZER; |
|
|
2134 | |
|
|
2135 | static void |
|
|
2136 | otherthread (void) |
|
|
2137 | { |
|
|
2138 | // only need to lock the actual queueing operation |
|
|
2139 | pthread_mutex_lock (&mymutex); |
|
|
2140 | queue_put (data); |
|
|
2141 | pthread_mutex_unlock (&mymutex); |
|
|
2142 | |
|
|
2143 | ev_async_send (DEFAULT_ &mysig); |
|
|
2144 | } |
|
|
2145 | |
|
|
2146 | static void |
|
|
2147 | mysig_cb (EV_P_ ev_async *w, int revents) |
|
|
2148 | { |
|
|
2149 | pthread_mutex_lock (&mymutex); |
|
|
2150 | |
|
|
2151 | while (queue_get (&data)) |
|
|
2152 | process (data); |
|
|
2153 | |
|
|
2154 | pthread_mutex_unlock (&mymutex); |
|
|
2155 | } |
|
|
2156 | |
|
|
2157 | =back |
|
|
2158 | |
|
|
2159 | |
|
|
2160 | =head3 Watcher-Specific Functions and Data Members |
|
|
2161 | |
|
|
2162 | =over 4 |
|
|
2163 | |
|
|
2164 | =item ev_async_init (ev_async *, callback) |
|
|
2165 | |
|
|
2166 | Initialises and configures the async watcher - it has no parameters of any |
|
|
2167 | kind. There is a C<ev_asynd_set> macro, but using it is utterly pointless, |
|
|
2168 | believe me. |
|
|
2169 | |
|
|
2170 | =item ev_async_send (loop, ev_async *) |
|
|
2171 | |
|
|
2172 | Sends/signals/activates the given C<ev_async> watcher, that is, feeds |
|
|
2173 | an C<EV_ASYNC> event on the watcher into the event loop. Unlike |
|
|
2174 | C<ev_feed_event>, this call is safe to do in other threads, signal or |
|
|
2175 | similar contexts (see the dicusssion of C<EV_ATOMIC_T> in the embedding |
|
|
2176 | section below on what exactly this means). |
|
|
2177 | |
|
|
2178 | This call incurs the overhead of a syscall only once per loop iteration, |
|
|
2179 | so while the overhead might be noticable, it doesn't apply to repeated |
|
|
2180 | calls to C<ev_async_send>. |
|
|
2181 | |
|
|
2182 | =back |
|
|
2183 | |
|
|
2184 | |
2044 | =head1 OTHER FUNCTIONS |
2185 | =head1 OTHER FUNCTIONS |
2045 | |
2186 | |
2046 | There are some other functions of possible interest. Described. Here. Now. |
2187 | There are some other functions of possible interest. Described. Here. Now. |
2047 | |
2188 | |
2048 | =over 4 |
2189 | =over 4 |
… | |
… | |
2275 | Example: Define a class with an IO and idle watcher, start one of them in |
2416 | Example: Define a class with an IO and idle watcher, start one of them in |
2276 | the constructor. |
2417 | the constructor. |
2277 | |
2418 | |
2278 | class myclass |
2419 | class myclass |
2279 | { |
2420 | { |
2280 | ev_io io; void io_cb (ev::io &w, int revents); |
2421 | ev::io io; void io_cb (ev::io &w, int revents); |
2281 | ev_idle idle void idle_cb (ev::idle &w, int revents); |
2422 | ev:idle idle void idle_cb (ev::idle &w, int revents); |
2282 | |
2423 | |
2283 | myclass (); |
2424 | myclass (int fd) |
2284 | } |
|
|
2285 | |
|
|
2286 | myclass::myclass (int fd) |
|
|
2287 | { |
2425 | { |
2288 | io .set <myclass, &myclass::io_cb > (this); |
2426 | io .set <myclass, &myclass::io_cb > (this); |
2289 | idle.set <myclass, &myclass::idle_cb> (this); |
2427 | idle.set <myclass, &myclass::idle_cb> (this); |
2290 | |
2428 | |
2291 | io.start (fd, ev::READ); |
2429 | io.start (fd, ev::READ); |
|
|
2430 | } |
2292 | } |
2431 | }; |
2293 | |
2432 | |
2294 | |
2433 | |
2295 | =head1 MACRO MAGIC |
2434 | =head1 MACRO MAGIC |
2296 | |
2435 | |
2297 | Libev can be compiled with a variety of options, the most fundamantal |
2436 | Libev can be compiled with a variety of options, the most fundamantal |
… | |
… | |
2553 | |
2692 | |
2554 | If defined to be C<1>, libev will compile in support for the Linux inotify |
2693 | If defined to be C<1>, libev will compile in support for the Linux inotify |
2555 | interface to speed up C<ev_stat> watchers. Its actual availability will |
2694 | interface to speed up C<ev_stat> watchers. Its actual availability will |
2556 | be detected at runtime. |
2695 | be detected at runtime. |
2557 | |
2696 | |
|
|
2697 | =item EV_ATOMIC_T |
|
|
2698 | |
|
|
2699 | Libev requires an integer type (suitable for storing C<0> or C<1>) whose |
|
|
2700 | access is atomic with respect to other threads or signal contexts. No such type |
|
|
2701 | is easily found using, so you cna provide your own type that you know is safe. |
|
|
2702 | |
|
|
2703 | In the absense of this define, libev will use C<sig_atomic_t volatile> |
|
|
2704 | from F<signal.h>, which is usually good enough on most platforms. |
|
|
2705 | |
2558 | =item EV_H |
2706 | =item EV_H |
2559 | |
2707 | |
2560 | The name of the F<ev.h> header file used to include it. The default if |
2708 | The name of the F<ev.h> header file used to include it. The default if |
2561 | undefined is C<"ev.h"> in F<event.h> and F<ev.c>. This can be used to |
2709 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
2562 | virtually rename the F<ev.h> header file in case of conflicts. |
2710 | used to virtually rename the F<ev.h> header file in case of conflicts. |
2563 | |
2711 | |
2564 | =item EV_CONFIG_H |
2712 | =item EV_CONFIG_H |
2565 | |
2713 | |
2566 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
2714 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
2567 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
2715 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
2568 | C<EV_H>, above. |
2716 | C<EV_H>, above. |
2569 | |
2717 | |
2570 | =item EV_EVENT_H |
2718 | =item EV_EVENT_H |
2571 | |
2719 | |
2572 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
2720 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
2573 | of how the F<event.h> header can be found, the dfeault is C<"event.h">. |
2721 | of how the F<event.h> header can be found, the default is C<"event.h">. |
2574 | |
2722 | |
2575 | =item EV_PROTOTYPES |
2723 | =item EV_PROTOTYPES |
2576 | |
2724 | |
2577 | If defined to be C<0>, then F<ev.h> will not define any function |
2725 | If defined to be C<0>, then F<ev.h> will not define any function |
2578 | prototypes, but still define all the structs and other symbols. This is |
2726 | prototypes, but still define all the structs and other symbols. This is |
… | |
… | |
2627 | defined to be C<0>, then they are not. |
2775 | defined to be C<0>, then they are not. |
2628 | |
2776 | |
2629 | =item EV_FORK_ENABLE |
2777 | =item EV_FORK_ENABLE |
2630 | |
2778 | |
2631 | If undefined or defined to be C<1>, then fork watchers are supported. If |
2779 | If undefined or defined to be C<1>, then fork watchers are supported. If |
|
|
2780 | defined to be C<0>, then they are not. |
|
|
2781 | |
|
|
2782 | =item EV_ASYNC_ENABLE |
|
|
2783 | |
|
|
2784 | If undefined or defined to be C<1>, then async watchers are supported. If |
2632 | defined to be C<0>, then they are not. |
2785 | defined to be C<0>, then they are not. |
2633 | |
2786 | |
2634 | =item EV_MINIMAL |
2787 | =item EV_MINIMAL |
2635 | |
2788 | |
2636 | If you need to shave off some kilobytes of code at the expense of some |
2789 | If you need to shave off some kilobytes of code at the expense of some |