… | |
… | |
862 | |
862 | |
863 | This call will simply invoke all pending watchers while resetting their |
863 | This call will simply invoke all pending watchers while resetting their |
864 | pending state. Normally, C<ev_loop> does this automatically when required, |
864 | pending state. Normally, C<ev_loop> does this automatically when required, |
865 | but when overriding the invoke callback this call comes handy. |
865 | but when overriding the invoke callback this call comes handy. |
866 | |
866 | |
|
|
867 | =item int ev_pending_count (loop) |
|
|
868 | |
|
|
869 | Returns the number of pending watchers - zero indicates that no watchers |
|
|
870 | are pending. |
|
|
871 | |
867 | =item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P)) |
872 | =item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P)) |
868 | |
873 | |
869 | This overrides the invoke pending functionality of the loop: Instead of |
874 | This overrides the invoke pending functionality of the loop: Instead of |
870 | invoking all pending watchers when there are any, C<ev_loop> will call |
875 | invoking all pending watchers when there are any, C<ev_loop> will call |
871 | this callback instead. This is useful, for example, when you want to |
876 | this callback instead. This is useful, for example, when you want to |
… | |
… | |
1750 | |
1755 | |
1751 | If the event loop is suspended for a long time, you can also force an |
1756 | If the event loop is suspended for a long time, you can also force an |
1752 | update of the time returned by C<ev_now ()> by calling C<ev_now_update |
1757 | update of the time returned by C<ev_now ()> by calling C<ev_now_update |
1753 | ()>. |
1758 | ()>. |
1754 | |
1759 | |
|
|
1760 | =head3 The special problems of suspended animation |
|
|
1761 | |
|
|
1762 | When you leave the server world it is quite customary to hit machines that |
|
|
1763 | can suspend/hibernate - what happens to the clocks during such a suspend? |
|
|
1764 | |
|
|
1765 | Some quick tests made with a Linux 2.6.28 indicate that a suspend freezes |
|
|
1766 | all processes, while the clocks (C<times>, C<CLOCK_MONOTONIC>) continue |
|
|
1767 | to run until the system is suspended, but they will not advance while the |
|
|
1768 | system is suspended. That means, on resume, it will be as if the program |
|
|
1769 | was frozen for a few seconds, but the suspend time will not be counted |
|
|
1770 | towards C<ev_timer> when a monotonic clock source is used. The real time |
|
|
1771 | clock advanced as expected, but if it is used as sole clocksource, then a |
|
|
1772 | long suspend would be detected as a time jump by libev, and timers would |
|
|
1773 | be adjusted accordingly. |
|
|
1774 | |
|
|
1775 | I would not be surprised to see different behaviour in different between |
|
|
1776 | operating systems, OS versions or even different hardware. |
|
|
1777 | |
|
|
1778 | The other form of suspend (job control, or sending a SIGSTOP) will see a |
|
|
1779 | time jump in the monotonic clocks and the realtime clock. If the program |
|
|
1780 | is suspended for a very long time, and monotonic clock sources are in use, |
|
|
1781 | then you can expect C<ev_timer>s to expire as the full suspension time |
|
|
1782 | will be counted towards the timers. When no monotonic clock source is in |
|
|
1783 | use, then libev will again assume a timejump and adjust accordingly. |
|
|
1784 | |
|
|
1785 | It might be beneficial for this latter case to call C<ev_suspend> |
|
|
1786 | and C<ev_resume> in code that handles C<SIGTSTP>, to at least get |
|
|
1787 | deterministic behaviour in this case (you can do nothing against |
|
|
1788 | C<SIGSTOP>). |
|
|
1789 | |
1755 | =head3 Watcher-Specific Functions and Data Members |
1790 | =head3 Watcher-Specific Functions and Data Members |
1756 | |
1791 | |
1757 | =over 4 |
1792 | =over 4 |
1758 | |
1793 | |
1759 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
1794 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
… | |
… | |
1784 | If the timer is repeating, either start it if necessary (with the |
1819 | If the timer is repeating, either start it if necessary (with the |
1785 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1820 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1786 | |
1821 | |
1787 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
1822 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
1788 | usage example. |
1823 | usage example. |
|
|
1824 | |
|
|
1825 | =item ev_timer_remaining (loop, ev_timer *) |
|
|
1826 | |
|
|
1827 | Returns the remaining time until a timer fires. If the timer is active, |
|
|
1828 | then this time is relative to the current event loop time, otherwise it's |
|
|
1829 | the timeout value currently configured. |
|
|
1830 | |
|
|
1831 | That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns |
|
|
1832 | C<5>. When the timer is started and one second passes, C<ev_timer_remain> |
|
|
1833 | will return C<4>. When the timer expires and is restarted, it will return |
|
|
1834 | roughly C<7> (likely slightly less as callback invocation takes some time, |
|
|
1835 | too), and so on. |
1789 | |
1836 | |
1790 | =item ev_tstamp repeat [read-write] |
1837 | =item ev_tstamp repeat [read-write] |
1791 | |
1838 | |
1792 | The current C<repeat> value. Will be used each time the watcher times out |
1839 | The current C<repeat> value. Will be used each time the watcher times out |
1793 | or C<ev_timer_again> is called, and determines the next timeout (if any), |
1840 | or C<ev_timer_again> is called, and determines the next timeout (if any), |
… | |
… | |
3998 | protecting the loop data, respectively. |
4045 | protecting the loop data, respectively. |
3999 | |
4046 | |
4000 | static void |
4047 | static void |
4001 | l_release (EV_P) |
4048 | l_release (EV_P) |
4002 | { |
4049 | { |
4003 | udat *u = ev_userdata (EV_A); |
4050 | userdata *u = ev_userdata (EV_A); |
4004 | pthread_mutex_unlock (&u->lock); |
4051 | pthread_mutex_unlock (&u->lock); |
4005 | } |
4052 | } |
4006 | |
4053 | |
4007 | static void |
4054 | static void |
4008 | l_acquire (EV_P) |
4055 | l_acquire (EV_P) |
4009 | { |
4056 | { |
4010 | udat *u = ev_userdata (EV_A); |
4057 | userdata *u = ev_userdata (EV_A); |
4011 | pthread_mutex_lock (&u->lock); |
4058 | pthread_mutex_lock (&u->lock); |
4012 | } |
4059 | } |
4013 | |
4060 | |
4014 | The event loop thread first acquires the mutex, and then jumps straight |
4061 | The event loop thread first acquires the mutex, and then jumps straight |
4015 | into C<ev_loop>: |
4062 | into C<ev_loop>: |
… | |
… | |
4028 | } |
4075 | } |
4029 | |
4076 | |
4030 | Instead of invoking all pending watchers, the C<l_invoke> callback will |
4077 | Instead of invoking all pending watchers, the C<l_invoke> callback will |
4031 | signal the main thread via some unspecified mechanism (signals? pipe |
4078 | signal the main thread via some unspecified mechanism (signals? pipe |
4032 | writes? C<Async::Interrupt>?) and then waits until all pending watchers |
4079 | writes? C<Async::Interrupt>?) and then waits until all pending watchers |
4033 | have been called: |
4080 | have been called (in a while loop because a) spurious wakeups are possible |
|
|
4081 | and b) skipping inter-thread-communication when there are no pending |
|
|
4082 | watchers is very beneficial): |
4034 | |
4083 | |
4035 | static void |
4084 | static void |
4036 | l_invoke (EV_P) |
4085 | l_invoke (EV_P) |
4037 | { |
4086 | { |
4038 | udat *u = ev_userdata (EV_A); |
4087 | userdata *u = ev_userdata (EV_A); |
4039 | |
4088 | |
|
|
4089 | while (ev_pending_count (EV_A)) |
|
|
4090 | { |
4040 | wake_up_other_thread_in_some_magic_or_not_so_magic_way (); |
4091 | wake_up_other_thread_in_some_magic_or_not_so_magic_way (); |
4041 | |
|
|
4042 | pthread_cond_wait (&u->invoke_cv, &u->lock); |
4092 | pthread_cond_wait (&u->invoke_cv, &u->lock); |
|
|
4093 | } |
4043 | } |
4094 | } |
4044 | |
4095 | |
4045 | Now, whenever the main thread gets told to invoke pending watchers, it |
4096 | Now, whenever the main thread gets told to invoke pending watchers, it |
4046 | will grab the lock, call C<ev_invoke_pending> and then signal the loop |
4097 | will grab the lock, call C<ev_invoke_pending> and then signal the loop |
4047 | thread to continue: |
4098 | thread to continue: |
4048 | |
4099 | |
4049 | static void |
4100 | static void |
4050 | real_invoke_pending (EV_P) |
4101 | real_invoke_pending (EV_P) |
4051 | { |
4102 | { |
4052 | udat *u = ev_userdata (EV_A); |
4103 | userdata *u = ev_userdata (EV_A); |
4053 | |
4104 | |
4054 | pthread_mutex_lock (&u->lock); |
4105 | pthread_mutex_lock (&u->lock); |
4055 | ev_invoke_pending (EV_A); |
4106 | ev_invoke_pending (EV_A); |
4056 | pthread_cond_signal (&u->invoke_cv); |
4107 | pthread_cond_signal (&u->invoke_cv); |
4057 | pthread_mutex_unlock (&u->lock); |
4108 | pthread_mutex_unlock (&u->lock); |
… | |
… | |
4059 | |
4110 | |
4060 | Whenever you want to start/stop a watcher or do other modifications to an |
4111 | Whenever you want to start/stop a watcher or do other modifications to an |
4061 | event loop, you will now have to lock: |
4112 | event loop, you will now have to lock: |
4062 | |
4113 | |
4063 | ev_timer timeout_watcher; |
4114 | ev_timer timeout_watcher; |
4064 | udat *u = ev_userdata (EV_A); |
4115 | userdata *u = ev_userdata (EV_A); |
4065 | |
4116 | |
4066 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
4117 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
4067 | |
4118 | |
4068 | pthread_mutex_lock (&u->lock); |
4119 | pthread_mutex_lock (&u->lock); |
4069 | ev_timer_start (EV_A_ &timeout_watcher); |
4120 | ev_timer_start (EV_A_ &timeout_watcher); |
… | |
… | |
4078 | =head3 COROUTINES |
4129 | =head3 COROUTINES |
4079 | |
4130 | |
4080 | Libev is very accommodating to coroutines ("cooperative threads"): |
4131 | Libev is very accommodating to coroutines ("cooperative threads"): |
4081 | libev fully supports nesting calls to its functions from different |
4132 | libev fully supports nesting calls to its functions from different |
4082 | coroutines (e.g. you can call C<ev_loop> on the same loop from two |
4133 | coroutines (e.g. you can call C<ev_loop> on the same loop from two |
4083 | different coroutines, and switch freely between both coroutines running the |
4134 | different coroutines, and switch freely between both coroutines running |
4084 | loop, as long as you don't confuse yourself). The only exception is that |
4135 | the loop, as long as you don't confuse yourself). The only exception is |
4085 | you must not do this from C<ev_periodic> reschedule callbacks. |
4136 | that you must not do this from C<ev_periodic> reschedule callbacks. |
4086 | |
4137 | |
4087 | Care has been taken to ensure that libev does not keep local state inside |
4138 | Care has been taken to ensure that libev does not keep local state inside |
4088 | C<ev_loop>, and other calls do not usually allow for coroutine switches as |
4139 | C<ev_loop>, and other calls do not usually allow for coroutine switches as |
4089 | they do not call any callbacks. |
4140 | they do not call any callbacks. |
4090 | |
4141 | |