… | |
… | |
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) |
… | |
… | |
3998 | protecting the loop data, respectively. |
4033 | protecting the loop data, respectively. |
3999 | |
4034 | |
4000 | static void |
4035 | static void |
4001 | l_release (EV_P) |
4036 | l_release (EV_P) |
4002 | { |
4037 | { |
4003 | udat *u = ev_userdata (EV_A); |
4038 | userdata *u = ev_userdata (EV_A); |
4004 | pthread_mutex_unlock (&u->lock); |
4039 | pthread_mutex_unlock (&u->lock); |
4005 | } |
4040 | } |
4006 | |
4041 | |
4007 | static void |
4042 | static void |
4008 | l_acquire (EV_P) |
4043 | l_acquire (EV_P) |
4009 | { |
4044 | { |
4010 | udat *u = ev_userdata (EV_A); |
4045 | userdata *u = ev_userdata (EV_A); |
4011 | pthread_mutex_lock (&u->lock); |
4046 | pthread_mutex_lock (&u->lock); |
4012 | } |
4047 | } |
4013 | |
4048 | |
4014 | The event loop thread first acquires the mutex, and then jumps straight |
4049 | The event loop thread first acquires the mutex, and then jumps straight |
4015 | into C<ev_loop>: |
4050 | into C<ev_loop>: |
… | |
… | |
4028 | } |
4063 | } |
4029 | |
4064 | |
4030 | Instead of invoking all pending watchers, the C<l_invoke> callback will |
4065 | Instead of invoking all pending watchers, the C<l_invoke> callback will |
4031 | signal the main thread via some unspecified mechanism (signals? pipe |
4066 | signal the main thread via some unspecified mechanism (signals? pipe |
4032 | writes? C<Async::Interrupt>?) and then waits until all pending watchers |
4067 | writes? C<Async::Interrupt>?) and then waits until all pending watchers |
4033 | have been called: |
4068 | have been called (in a while loop because a) spurious wakeups are possible |
|
|
4069 | and b) skipping inter-thread-communication when there are no pending |
|
|
4070 | watchers is very beneficial): |
4034 | |
4071 | |
4035 | static void |
4072 | static void |
4036 | l_invoke (EV_P) |
4073 | l_invoke (EV_P) |
4037 | { |
4074 | { |
4038 | udat *u = ev_userdata (EV_A); |
4075 | userdata *u = ev_userdata (EV_A); |
4039 | |
4076 | |
|
|
4077 | while (ev_pending_count (EV_A)) |
|
|
4078 | { |
4040 | wake_up_other_thread_in_some_magic_or_not_so_magic_way (); |
4079 | wake_up_other_thread_in_some_magic_or_not_so_magic_way (); |
4041 | |
|
|
4042 | pthread_cond_wait (&u->invoke_cv, &u->lock); |
4080 | pthread_cond_wait (&u->invoke_cv, &u->lock); |
|
|
4081 | } |
4043 | } |
4082 | } |
4044 | |
4083 | |
4045 | Now, whenever the main thread gets told to invoke pending watchers, it |
4084 | 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 |
4085 | will grab the lock, call C<ev_invoke_pending> and then signal the loop |
4047 | thread to continue: |
4086 | thread to continue: |
4048 | |
4087 | |
4049 | static void |
4088 | static void |
4050 | real_invoke_pending (EV_P) |
4089 | real_invoke_pending (EV_P) |
4051 | { |
4090 | { |
4052 | udat *u = ev_userdata (EV_A); |
4091 | userdata *u = ev_userdata (EV_A); |
4053 | |
4092 | |
4054 | pthread_mutex_lock (&u->lock); |
4093 | pthread_mutex_lock (&u->lock); |
4055 | ev_invoke_pending (EV_A); |
4094 | ev_invoke_pending (EV_A); |
4056 | pthread_cond_signal (&u->invoke_cv); |
4095 | pthread_cond_signal (&u->invoke_cv); |
4057 | pthread_mutex_unlock (&u->lock); |
4096 | pthread_mutex_unlock (&u->lock); |
… | |
… | |
4059 | |
4098 | |
4060 | Whenever you want to start/stop a watcher or do other modifications to an |
4099 | Whenever you want to start/stop a watcher or do other modifications to an |
4061 | event loop, you will now have to lock: |
4100 | event loop, you will now have to lock: |
4062 | |
4101 | |
4063 | ev_timer timeout_watcher; |
4102 | ev_timer timeout_watcher; |
4064 | udat *u = ev_userdata (EV_A); |
4103 | userdata *u = ev_userdata (EV_A); |
4065 | |
4104 | |
4066 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
4105 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
4067 | |
4106 | |
4068 | pthread_mutex_lock (&u->lock); |
4107 | pthread_mutex_lock (&u->lock); |
4069 | ev_timer_start (EV_A_ &timeout_watcher); |
4108 | ev_timer_start (EV_A_ &timeout_watcher); |
… | |
… | |
4078 | =head3 COROUTINES |
4117 | =head3 COROUTINES |
4079 | |
4118 | |
4080 | Libev is very accommodating to coroutines ("cooperative threads"): |
4119 | Libev is very accommodating to coroutines ("cooperative threads"): |
4081 | libev fully supports nesting calls to its functions from different |
4120 | 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 |
4121 | 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 |
4122 | different coroutines, and switch freely between both coroutines running |
4084 | loop, as long as you don't confuse yourself). The only exception is that |
4123 | 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. |
4124 | that you must not do this from C<ev_periodic> reschedule callbacks. |
4086 | |
4125 | |
4087 | Care has been taken to ensure that libev does not keep local state inside |
4126 | 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 |
4127 | C<ev_loop>, and other calls do not usually allow for coroutine switches as |
4089 | they do not call any callbacks. |
4128 | they do not call any callbacks. |
4090 | |
4129 | |