… | |
… | |
47 | |
47 | |
48 | return 0; |
48 | return 0; |
49 | } |
49 | } |
50 | |
50 | |
51 | =head1 DESCRIPTION |
51 | =head1 DESCRIPTION |
|
|
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>. |
52 | |
56 | |
53 | 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 |
54 | file descriptor being readable or a timeout occuring), and it will manage |
58 | file descriptor being readable or a timeout occuring), and it will manage |
55 | these event sources and provide your program with events. |
59 | these event sources and provide your program with events. |
56 | |
60 | |
… | |
… | |
266 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
270 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
267 | override the flags completely if it is found in the environment. This is |
271 | override the flags completely if it is found in the environment. This is |
268 | useful to try out specific backends to test their performance, or to work |
272 | useful to try out specific backends to test their performance, or to work |
269 | around bugs. |
273 | around bugs. |
270 | |
274 | |
|
|
275 | =item C<EVFLAG_FORKCHECK> |
|
|
276 | |
|
|
277 | Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after |
|
|
278 | a fork, you can also make libev check for a fork in each iteration by |
|
|
279 | enabling this flag. |
|
|
280 | |
|
|
281 | This works by calling C<getpid ()> on every iteration of the loop, |
|
|
282 | and thus this might slow down your event loop if you do a lot of loop |
|
|
283 | iterations and little real work, but is usually not noticeable (on my |
|
|
284 | Linux system for example, C<getpid> is actually a simple 5-insn sequence |
|
|
285 | without a syscall and thus I<very> fast, but my Linux system also has |
|
|
286 | C<pthread_atfork> which is even faster). |
|
|
287 | |
|
|
288 | The big advantage of this flag is that you can forget about fork (and |
|
|
289 | forget about forgetting to tell libev about forking) when you use this |
|
|
290 | flag. |
|
|
291 | |
|
|
292 | This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS> |
|
|
293 | environment variable. |
|
|
294 | |
271 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
295 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
272 | |
296 | |
273 | This is your standard select(2) backend. Not I<completely> standard, as |
297 | This is your standard select(2) backend. Not I<completely> standard, as |
274 | libev tries to roll its own fd_set with no limits on the number of fds, |
298 | libev tries to roll its own fd_set with no limits on the number of fds, |
275 | but if that fails, expect a fairly low limit on the number of fds when |
299 | but if that fails, expect a fairly low limit on the number of fds when |
… | |
… | |
409 | =item ev_loop_fork (loop) |
433 | =item ev_loop_fork (loop) |
410 | |
434 | |
411 | Like C<ev_default_fork>, but acts on an event loop created by |
435 | Like C<ev_default_fork>, but acts on an event loop created by |
412 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
436 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
413 | after fork, and how you do this is entirely your own problem. |
437 | after fork, and how you do this is entirely your own problem. |
|
|
438 | |
|
|
439 | =item unsigned int ev_loop_count (loop) |
|
|
440 | |
|
|
441 | Returns the count of loop iterations for the loop, which is identical to |
|
|
442 | the number of times libev did poll for new events. It starts at C<0> and |
|
|
443 | happily wraps around with enough iterations. |
|
|
444 | |
|
|
445 | This value can sometimes be useful as a generation counter of sorts (it |
|
|
446 | "ticks" the number of loop iterations), as it roughly corresponds with |
|
|
447 | C<ev_prepare> and C<ev_check> calls. |
414 | |
448 | |
415 | =item unsigned int ev_backend (loop) |
449 | =item unsigned int ev_backend (loop) |
416 | |
450 | |
417 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
451 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
418 | use. |
452 | use. |
… | |
… | |
714 | =item ev_cb_set (ev_TYPE *watcher, callback) |
748 | =item ev_cb_set (ev_TYPE *watcher, callback) |
715 | |
749 | |
716 | Change the callback. You can change the callback at virtually any time |
750 | Change the callback. You can change the callback at virtually any time |
717 | (modulo threads). |
751 | (modulo threads). |
718 | |
752 | |
|
|
753 | =item ev_set_priority (ev_TYPE *watcher, priority) |
|
|
754 | |
|
|
755 | =item int ev_priority (ev_TYPE *watcher) |
|
|
756 | |
|
|
757 | Set and query the priority of the watcher. The priority is a small |
|
|
758 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
|
|
759 | (default: C<-2>). Pending watchers with higher priority will be invoked |
|
|
760 | before watchers with lower priority, but priority will not keep watchers |
|
|
761 | from being executed (except for C<ev_idle> watchers). |
|
|
762 | |
|
|
763 | This means that priorities are I<only> used for ordering callback |
|
|
764 | invocation after new events have been received. This is useful, for |
|
|
765 | example, to reduce latency after idling, or more often, to bind two |
|
|
766 | watchers on the same event and make sure one is called first. |
|
|
767 | |
|
|
768 | If you need to suppress invocation when higher priority events are pending |
|
|
769 | you need to look at C<ev_idle> watchers, which provide this functionality. |
|
|
770 | |
|
|
771 | The default priority used by watchers when no priority has been set is |
|
|
772 | always C<0>, which is supposed to not be too high and not be too low :). |
|
|
773 | |
|
|
774 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
|
|
775 | fine, as long as you do not mind that the priority value you query might |
|
|
776 | or might not have been adjusted to be within valid range. |
|
|
777 | |
719 | =back |
778 | =back |
720 | |
779 | |
721 | |
780 | |
722 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
781 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
723 | |
782 | |
… | |
… | |
828 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
887 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
829 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
888 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
830 | |
889 | |
831 | If you cannot run the fd in non-blocking mode (for example you should not |
890 | If you cannot run the fd in non-blocking mode (for example you should not |
832 | play around with an Xlib connection), then you have to seperately re-test |
891 | play around with an Xlib connection), then you have to seperately re-test |
833 | wether a file descriptor is really ready with a known-to-be good interface |
892 | whether a file descriptor is really ready with a known-to-be good interface |
834 | such as poll (fortunately in our Xlib example, Xlib already does this on |
893 | such as poll (fortunately in our Xlib example, Xlib already does this on |
835 | its own, so its quite safe to use). |
894 | its own, so its quite safe to use). |
836 | |
895 | |
837 | =over 4 |
896 | =over 4 |
838 | |
897 | |
… | |
… | |
1321 | ev_stat_start (loop, &passwd); |
1380 | ev_stat_start (loop, &passwd); |
1322 | |
1381 | |
1323 | |
1382 | |
1324 | =head2 C<ev_idle> - when you've got nothing better to do... |
1383 | =head2 C<ev_idle> - when you've got nothing better to do... |
1325 | |
1384 | |
1326 | Idle watchers trigger events when there are no other events are pending |
1385 | Idle watchers trigger events when no other events of the same or higher |
1327 | (prepare, check and other idle watchers do not count). That is, as long |
1386 | priority are pending (prepare, check and other idle watchers do not |
1328 | as your process is busy handling sockets or timeouts (or even signals, |
1387 | count). |
1329 | imagine) it will not be triggered. But when your process is idle all idle |
1388 | |
1330 | watchers are being called again and again, once per event loop iteration - |
1389 | That is, as long as your process is busy handling sockets or timeouts |
|
|
1390 | (or even signals, imagine) of the same or higher priority it will not be |
|
|
1391 | triggered. But when your process is idle (or only lower-priority watchers |
|
|
1392 | are pending), the idle watchers are being called once per event loop |
1331 | until stopped, that is, or your process receives more events and becomes |
1393 | iteration - until stopped, that is, or your process receives more events |
1332 | busy. |
1394 | and becomes busy again with higher priority stuff. |
1333 | |
1395 | |
1334 | The most noteworthy effect is that as long as any idle watchers are |
1396 | The most noteworthy effect is that as long as any idle watchers are |
1335 | active, the process will not block when waiting for new events. |
1397 | active, the process will not block when waiting for new events. |
1336 | |
1398 | |
1337 | Apart from keeping your process non-blocking (which is a useful |
1399 | Apart from keeping your process non-blocking (which is a useful |
… | |
… | |
1437 | |
1499 | |
1438 | // create io watchers for each fd and a timer before blocking |
1500 | // create io watchers for each fd and a timer before blocking |
1439 | static void |
1501 | static void |
1440 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1502 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1441 | { |
1503 | { |
1442 | int timeout = 3600000;truct pollfd fds [nfd]; |
1504 | int timeout = 3600000; |
|
|
1505 | struct pollfd fds [nfd]; |
1443 | // actual code will need to loop here and realloc etc. |
1506 | // actual code will need to loop here and realloc etc. |
1444 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1507 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1445 | |
1508 | |
1446 | /* the callback is illegal, but won't be called as we stop during check */ |
1509 | /* the callback is illegal, but won't be called as we stop during check */ |
1447 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1510 | ev_timer_init (&tw, 0, timeout * 1e-3); |
… | |
… | |
1785 | |
1848 | |
1786 | |
1849 | |
1787 | =head1 MACRO MAGIC |
1850 | =head1 MACRO MAGIC |
1788 | |
1851 | |
1789 | Libev can be compiled with a variety of options, the most fundemantal is |
1852 | Libev can be compiled with a variety of options, the most fundemantal is |
1790 | C<EV_MULTIPLICITY>. This option determines wether (most) functions and |
1853 | C<EV_MULTIPLICITY>. This option determines whether (most) functions and |
1791 | callbacks have an initial C<struct ev_loop *> argument. |
1854 | callbacks have an initial C<struct ev_loop *> argument. |
1792 | |
1855 | |
1793 | To make it easier to write programs that cope with either variant, the |
1856 | To make it easier to write programs that cope with either variant, the |
1794 | following macros are defined: |
1857 | following macros are defined: |
1795 | |
1858 | |
… | |
… | |
1828 | Similar to the other two macros, this gives you the value of the default |
1891 | Similar to the other two macros, this gives you the value of the default |
1829 | loop, if multiple loops are supported ("ev loop default"). |
1892 | loop, if multiple loops are supported ("ev loop default"). |
1830 | |
1893 | |
1831 | =back |
1894 | =back |
1832 | |
1895 | |
1833 | Example: Declare and initialise a check watcher, working regardless of |
1896 | Example: Declare and initialise a check watcher, utilising the above |
1834 | wether multiple loops are supported or not. |
1897 | macros so it will work regardless of whether multiple loops are supported |
|
|
1898 | or not. |
1835 | |
1899 | |
1836 | static void |
1900 | static void |
1837 | check_cb (EV_P_ ev_timer *w, int revents) |
1901 | check_cb (EV_P_ ev_timer *w, int revents) |
1838 | { |
1902 | { |
1839 | ev_check_stop (EV_A_ w); |
1903 | ev_check_stop (EV_A_ w); |
… | |
… | |
1842 | ev_check check; |
1906 | ev_check check; |
1843 | ev_check_init (&check, check_cb); |
1907 | ev_check_init (&check, check_cb); |
1844 | ev_check_start (EV_DEFAULT_ &check); |
1908 | ev_check_start (EV_DEFAULT_ &check); |
1845 | ev_loop (EV_DEFAULT_ 0); |
1909 | ev_loop (EV_DEFAULT_ 0); |
1846 | |
1910 | |
1847 | |
|
|
1848 | =head1 EMBEDDING |
1911 | =head1 EMBEDDING |
1849 | |
1912 | |
1850 | Libev can (and often is) directly embedded into host |
1913 | Libev can (and often is) directly embedded into host |
1851 | applications. Examples of applications that embed it include the Deliantra |
1914 | applications. Examples of applications that embed it include the Deliantra |
1852 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
1915 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
… | |
… | |
1891 | ev_vars.h |
1954 | ev_vars.h |
1892 | ev_wrap.h |
1955 | ev_wrap.h |
1893 | |
1956 | |
1894 | ev_win32.c required on win32 platforms only |
1957 | ev_win32.c required on win32 platforms only |
1895 | |
1958 | |
1896 | ev_select.c only when select backend is enabled (which is by default) |
1959 | ev_select.c only when select backend is enabled (which is enabled by default) |
1897 | ev_poll.c only when poll backend is enabled (disabled by default) |
1960 | ev_poll.c only when poll backend is enabled (disabled by default) |
1898 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
1961 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
1899 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
1962 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
1900 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
1963 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
1901 | |
1964 | |
… | |
… | |
2064 | will have the C<struct ev_loop *> as first argument, and you can create |
2127 | will have the C<struct ev_loop *> as first argument, and you can create |
2065 | additional independent event loops. Otherwise there will be no support |
2128 | additional independent event loops. Otherwise there will be no support |
2066 | for multiple event loops and there is no first event loop pointer |
2129 | for multiple event loops and there is no first event loop pointer |
2067 | argument. Instead, all functions act on the single default loop. |
2130 | argument. Instead, all functions act on the single default loop. |
2068 | |
2131 | |
|
|
2132 | =item EV_MINPRI |
|
|
2133 | |
|
|
2134 | =item EV_MAXPRI |
|
|
2135 | |
|
|
2136 | The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to |
|
|
2137 | C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can |
|
|
2138 | provide for more priorities by overriding those symbols (usually defined |
|
|
2139 | to be C<-2> and C<2>, respectively). |
|
|
2140 | |
|
|
2141 | When doing priority-based operations, libev usually has to linearly search |
|
|
2142 | all the priorities, so having many of them (hundreds) uses a lot of space |
|
|
2143 | and time, so using the defaults of five priorities (-2 .. +2) is usually |
|
|
2144 | fine. |
|
|
2145 | |
|
|
2146 | If your embedding app does not need any priorities, defining these both to |
|
|
2147 | C<0> will save some memory and cpu. |
|
|
2148 | |
2069 | =item EV_PERIODIC_ENABLE |
2149 | =item EV_PERIODIC_ENABLE |
2070 | |
2150 | |
2071 | If undefined or defined to be C<1>, then periodic timers are supported. If |
2151 | If undefined or defined to be C<1>, then periodic timers are supported. If |
|
|
2152 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
2153 | code. |
|
|
2154 | |
|
|
2155 | =item EV_IDLE_ENABLE |
|
|
2156 | |
|
|
2157 | If undefined or defined to be C<1>, then idle watchers are supported. If |
2072 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
2158 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
2073 | code. |
2159 | code. |
2074 | |
2160 | |
2075 | =item EV_EMBED_ENABLE |
2161 | =item EV_EMBED_ENABLE |
2076 | |
2162 | |
… | |
… | |
2143 | interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file |
2229 | interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file |
2144 | will be compiled. It is pretty complex because it provides its own header |
2230 | will be compiled. It is pretty complex because it provides its own header |
2145 | file. |
2231 | file. |
2146 | |
2232 | |
2147 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
2233 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
2148 | that everybody includes and which overrides some autoconf choices: |
2234 | that everybody includes and which overrides some configure choices: |
2149 | |
2235 | |
|
|
2236 | #define EV_MINIMAL 1 |
2150 | #define EV_USE_POLL 0 |
2237 | #define EV_USE_POLL 0 |
2151 | #define EV_MULTIPLICITY 0 |
2238 | #define EV_MULTIPLICITY 0 |
2152 | #define EV_PERIODICS 0 |
2239 | #define EV_PERIODIC_ENABLE 0 |
|
|
2240 | #define EV_STAT_ENABLE 0 |
|
|
2241 | #define EV_FORK_ENABLE 0 |
2153 | #define EV_CONFIG_H <config.h> |
2242 | #define EV_CONFIG_H <config.h> |
|
|
2243 | #define EV_MINPRI 0 |
|
|
2244 | #define EV_MAXPRI 0 |
2154 | |
2245 | |
2155 | #include "ev++.h" |
2246 | #include "ev++.h" |
2156 | |
2247 | |
2157 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
2248 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
2158 | |
2249 | |
… | |
… | |
2168 | |
2259 | |
2169 | =over 4 |
2260 | =over 4 |
2170 | |
2261 | |
2171 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2262 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2172 | |
2263 | |
|
|
2264 | This means that, when you have a watcher that triggers in one hour and |
|
|
2265 | there are 100 watchers that would trigger before that then inserting will |
|
|
2266 | have to skip those 100 watchers. |
|
|
2267 | |
2173 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
2268 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
2174 | |
2269 | |
|
|
2270 | That means that for changing a timer costs less than removing/adding them |
|
|
2271 | as only the relative motion in the event queue has to be paid for. |
|
|
2272 | |
2175 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2273 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2176 | |
2274 | |
|
|
2275 | These just add the watcher into an array or at the head of a list. If |
|
|
2276 | the array needs to be extended libev needs to realloc and move the whole |
|
|
2277 | array, but this happen asymptotically less and less with more watchers, |
|
|
2278 | thus amortised O(1). |
|
|
2279 | |
2177 | =item Stopping check/prepare/idle watchers: O(1) |
2280 | =item Stopping check/prepare/idle watchers: O(1) |
2178 | |
2281 | |
2179 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2282 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2180 | |
2283 | |
|
|
2284 | These watchers are stored in lists then need to be walked to find the |
|
|
2285 | correct watcher to remove. The lists are usually short (you don't usually |
|
|
2286 | have many watchers waiting for the same fd or signal). |
|
|
2287 | |
2181 | =item Finding the next timer per loop iteration: O(1) |
2288 | =item Finding the next timer per loop iteration: O(1) |
2182 | |
2289 | |
2183 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2290 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2184 | |
2291 | |
|
|
2292 | A change means an I/O watcher gets started or stopped, which requires |
|
|
2293 | libev to recalculate its status (and possibly tell the kernel). |
|
|
2294 | |
2185 | =item Activating one watcher: O(1) |
2295 | =item Activating one watcher: O(1) |
2186 | |
2296 | |
|
|
2297 | =item Priority handling: O(number_of_priorities) |
|
|
2298 | |
|
|
2299 | Priorities are implemented by allocating some space for each |
|
|
2300 | priority. When doing priority-based operations, libev usually has to |
|
|
2301 | linearly search all the priorities. |
|
|
2302 | |
2187 | =back |
2303 | =back |
2188 | |
2304 | |
2189 | |
2305 | |
2190 | =head1 AUTHOR |
2306 | =head1 AUTHOR |
2191 | |
2307 | |