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Comparing libev/ev.pod (file contents):
Revision 1.127 by root, Fri Feb 1 13:47:08 2008 UTC vs.
Revision 1.133 by root, Sun Feb 24 06:50:16 2008 UTC

505=item ev_loop_fork (loop) 505=item ev_loop_fork (loop)
506 506
507Like C<ev_default_fork>, but acts on an event loop created by 507Like C<ev_default_fork>, but acts on an event loop created by
508C<ev_loop_new>. Yes, you have to call this on every allocated event loop 508C<ev_loop_new>. Yes, you have to call this on every allocated event loop
509after fork, and how you do this is entirely your own problem. 509after fork, and how you do this is entirely your own problem.
510
511=item int ev_is_default_loop (loop)
512
513Returns true when the given loop actually is the default loop, false otherwise.
510 514
511=item unsigned int ev_loop_count (loop) 515=item unsigned int ev_loop_count (loop)
512 516
513Returns the count of loop iterations for the loop, which is identical to 517Returns the count of loop iterations for the loop, which is identical to
514the number of times libev did poll for new events. It starts at C<0> and 518the number of times libev did poll for new events. It starts at C<0> and
1152configure a timer to trigger every 10 seconds, then it will trigger at 1156configure a timer to trigger every 10 seconds, then it will trigger at
1153exactly 10 second intervals. If, however, your program cannot keep up with 1157exactly 10 second intervals. If, however, your program cannot keep up with
1154the timer (because it takes longer than those 10 seconds to do stuff) the 1158the timer (because it takes longer than those 10 seconds to do stuff) the
1155timer will not fire more than once per event loop iteration. 1159timer will not fire more than once per event loop iteration.
1156 1160
1157=item ev_timer_again (loop) 1161=item ev_timer_again (loop, ev_timer *)
1158 1162
1159This will act as if the timer timed out and restart it again if it is 1163This will act as if the timer timed out and restart it again if it is
1160repeating. The exact semantics are: 1164repeating. The exact semantics are:
1161 1165
1162If the timer is pending, its pending status is cleared. 1166If the timer is pending, its pending status is cleared.
1271In this configuration the watcher triggers an event at the wallclock time 1275In this configuration the watcher triggers an event at the wallclock time
1272C<at> and doesn't repeat. It will not adjust when a time jump occurs, 1276C<at> and doesn't repeat. It will not adjust when a time jump occurs,
1273that is, if it is to be run at January 1st 2011 then it will run when the 1277that is, if it is to be run at January 1st 2011 then it will run when the
1274system time reaches or surpasses this time. 1278system time reaches or surpasses this time.
1275 1279
1276=item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) 1280=item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
1277 1281
1278In this mode the watcher will always be scheduled to time out at the next 1282In this mode the watcher will always be scheduled to time out at the next
1279C<at + N * interval> time (for some integer N, which can also be negative) 1283C<at + N * interval> time (for some integer N, which can also be negative)
1280and then repeat, regardless of any time jumps. 1284and then repeat, regardless of any time jumps.
1281 1285
1431=item int signum [read-only] 1435=item int signum [read-only]
1432 1436
1433The signal the watcher watches out for. 1437The signal the watcher watches out for.
1434 1438
1435=back 1439=back
1440
1441=head3 Examples
1442
1443Example: Try to exit cleanly on SIGINT and SIGTERM.
1444
1445 static void
1446 sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1447 {
1448 ev_unloop (loop, EVUNLOOP_ALL);
1449 }
1450
1451 struct ev_signal signal_watcher;
1452 ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1453 ev_signal_start (loop, &sigint_cb);
1436 1454
1437 1455
1438=head2 C<ev_child> - watch out for process status changes 1456=head2 C<ev_child> - watch out for process status changes
1439 1457
1440Child watchers trigger when your process receives a SIGCHLD in response to 1458Child watchers trigger when your process receives a SIGCHLD in response to
1470The process exit/trace status caused by C<rpid> (see your systems 1488The process exit/trace status caused by C<rpid> (see your systems
1471C<waitpid> and C<sys/wait.h> documentation for details). 1489C<waitpid> and C<sys/wait.h> documentation for details).
1472 1490
1473=back 1491=back
1474 1492
1475=head3 Examples
1476
1477Example: 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 1493
1490=head2 C<ev_stat> - did the file attributes just change? 1494=head2 C<ev_stat> - did the file attributes just change?
1491 1495
1492This watches a filesystem path for attribute changes. That is, it calls 1496This watches a filesystem path for attribute changes. That is, it calls
1493C<stat> regularly (or when the OS says it changed) and sees if it changed 1497C<stat> regularly (or when the OS says it changed) and sees if it changed
1572 1576
1573The callback will be receive C<EV_STAT> when a change was detected, 1577The callback will be receive C<EV_STAT> when a change was detected,
1574relative to the attributes at the time the watcher was started (or the 1578relative to the attributes at the time the watcher was started (or the
1575last change was detected). 1579last change was detected).
1576 1580
1577=item ev_stat_stat (ev_stat *) 1581=item ev_stat_stat (loop, ev_stat *)
1578 1582
1579Updates the stat buffer immediately with new values. If you change the 1583Updates the stat buffer immediately with new values. If you change the
1580watched path in your callback, you could call this fucntion to avoid 1584watched path in your callback, you could call this fucntion to avoid
1581detecting this change (while introducing a race condition). Can also be 1585detecting this change (while introducing a race condition). Can also be
1582useful simply to find out the new values. 1586useful simply to find out the new values.
2078is that the author does not know of a simple (or any) algorithm for a 2082is that the author does not know of a simple (or any) algorithm for a
2079multiple-writer-single-reader queue that works in all cases and doesn't 2083multiple-writer-single-reader queue that works in all cases and doesn't
2080need elaborate support such as pthreads. 2084need elaborate support such as pthreads.
2081 2085
2082That means that if you want to queue data, you have to provide your own 2086That means that if you want to queue data, you have to provide your own
2083queue. And here is how you would implement locking: 2087queue. But at least I can tell you would implement locking around your
2088queue:
2084 2089
2085=over 4 2090=over 4
2086 2091
2087=item queueing from a signal handler context 2092=item queueing from a signal handler context
2088 2093
2097 { 2102 {
2098 sometype data; 2103 sometype data;
2099 2104
2100 // no locking etc. 2105 // no locking etc.
2101 queue_put (data); 2106 queue_put (data);
2102 ev_async_send (DEFAULT_ &mysig); 2107 ev_async_send (EV_DEFAULT_ &mysig);
2103 } 2108 }
2104 2109
2105 static void 2110 static void
2106 mysig_cb (EV_P_ ev_async *w, int revents) 2111 mysig_cb (EV_P_ ev_async *w, int revents)
2107 { 2112 {
2125 2130
2126=item queueing from a thread context 2131=item queueing from a thread context
2127 2132
2128The strategy for threads is different, as you cannot (easily) block 2133The strategy for threads is different, as you cannot (easily) block
2129threads but you can easily preempt them, so to queue safely you need to 2134threads but you can easily preempt them, so to queue safely you need to
2130emply a traditional mutex lock, such as in this pthread example: 2135employ a traditional mutex lock, such as in this pthread example:
2131 2136
2132 static ev_async mysig; 2137 static ev_async mysig;
2133 static pthread_mutex_t mymutex = PTHREAD_MUTEX_INITIALIZER; 2138 static pthread_mutex_t mymutex = PTHREAD_MUTEX_INITIALIZER;
2134 2139
2135 static void 2140 static void
2138 // only need to lock the actual queueing operation 2143 // only need to lock the actual queueing operation
2139 pthread_mutex_lock (&mymutex); 2144 pthread_mutex_lock (&mymutex);
2140 queue_put (data); 2145 queue_put (data);
2141 pthread_mutex_unlock (&mymutex); 2146 pthread_mutex_unlock (&mymutex);
2142 2147
2143 ev_async_send (DEFAULT_ &mysig); 2148 ev_async_send (EV_DEFAULT_ &mysig);
2144 } 2149 }
2145 2150
2146 static void 2151 static void
2147 mysig_cb (EV_P_ ev_async *w, int revents) 2152 mysig_cb (EV_P_ ev_async *w, int revents)
2148 { 2153 {
2912=item Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers) 2917=item Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers)
2913 2918
2914That means that changing a timer costs less than removing/adding them 2919That means that changing a timer costs less than removing/adding them
2915as only the relative motion in the event queue has to be paid for. 2920as only the relative motion in the event queue has to be paid for.
2916 2921
2917=item Starting io/check/prepare/idle/signal/child watchers: O(1) 2922=item Starting io/check/prepare/idle/signal/child/fork/async watchers: O(1)
2918 2923
2919These just add the watcher into an array or at the head of a list. 2924These just add the watcher into an array or at the head of a list.
2920 2925
2921=item Stopping check/prepare/idle watchers: O(1) 2926=item Stopping check/prepare/idle/fork/async watchers: O(1)
2922 2927
2923=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) 2928=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
2924 2929
2925These watchers are stored in lists then need to be walked to find the 2930These watchers are stored in lists then need to be walked to find the
2926correct watcher to remove. The lists are usually short (you don't usually 2931correct watcher to remove. The lists are usually short (you don't usually
2942=item Priority handling: O(number_of_priorities) 2947=item Priority handling: O(number_of_priorities)
2943 2948
2944Priorities are implemented by allocating some space for each 2949Priorities are implemented by allocating some space for each
2945priority. When doing priority-based operations, libev usually has to 2950priority. When doing priority-based operations, libev usually has to
2946linearly search all the priorities, but starting/stopping and activating 2951linearly search all the priorities, but starting/stopping and activating
2947watchers becomes O(1) w.r.t. prioritiy handling. 2952watchers becomes O(1) w.r.t. priority handling.
2953
2954=item Sending an ev_async: O(1)
2955
2956=item Processing ev_async_send: O(number_of_async_watchers)
2957
2958=item Processing signals: O(max_signal_number)
2959
2960Sending involves a syscall I<iff> there were no other C<ev_async_send>
2961calls in the current loop iteration. Checking for async and signal events
2962involves iterating over all running async watchers or all signal numbers.
2948 2963
2949=back 2964=back
2950 2965
2951 2966
2952=head1 Win32 platform limitations and workarounds 2967=head1 Win32 platform limitations and workarounds

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