[ViewVC] Diff of: cvs/libev/ev.pod

Comparing libev/ev.pod (file contents):
Revision 1.255 by root, Tue Jul 14 19:11:31 2009 UTC vs.
Revision 1.259 by root, Sun Jul 19 01:36:34 2009 UTC

…		…
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),
…		…
2029	Signal watchers will trigger an event when the process receives a specific	2076	Signal watchers will trigger an event when the process receives a specific
2030	signal one or more times. Even though signals are very asynchronous, libev	2077	signal one or more times. Even though signals are very asynchronous, libev
2031	will try it's best to deliver signals synchronously, i.e. as part of the	2078	will try it's best to deliver signals synchronously, i.e. as part of the
2032	normal event processing, like any other event.	2079	normal event processing, like any other event.
2033		2080
		2081	Note that only the default loop supports registering signal watchers
		2082	currently.
		2083
2034	If you want signals asynchronously, just use C<sigaction> as you would	2084	If you want signals asynchronously, just use C<sigaction> as you would
2035	do without libev and forget about sharing the signal. You can even use	2085	do without libev and forget about sharing the signal. You can even use
2036	C<ev_async> from a signal handler to synchronously wake up an event loop.	2086	C<ev_async> from a signal handler to synchronously wake up an event loop.
2037		2087
2038	You can configure as many watchers as you like per signal. Only when the	2088	You can configure as many watchers as you like per signal. Only when the
2039	first watcher gets started will libev actually register a signal handler	2089	first watcher gets started will libev actually register something with
2040	with the kernel (thus it coexists with your own signal handlers as long as	2090	the kernel (thus it coexists with your own signal handlers as long as you
2041	you don't register any with libev for the same signal). Similarly, when	2091	don't register any with libev for the same signal).
2042	the last signal watcher for a signal is stopped, libev will reset the	2092
2043	signal handler to SIG_DFL (regardless of what it was set to before).	2093	Both the signal mask state (C<sigprocmask>) and the signal handler state
		2094	(C<sigaction>) are unspecified after starting a signal watcher (and after
		2095	sotpping it again), that is, libev might or might not block the signal,
		2096	and might or might not set or restore the installed signal handler.
2044		2097
2045	If possible and supported, libev will install its handlers with	2098	If possible and supported, libev will install its handlers with
2046	C<SA_RESTART> behaviour enabled, so system calls should not be unduly	2099	C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should
2047	interrupted. If you have a problem with system calls getting interrupted by	2100	not be unduly interrupted. If you have a problem with system calls getting
2048	signals you can block all signals in an C<ev_check> watcher and unblock	2101	interrupted by signals you can block all signals in an C<ev_check> watcher
2049	them in an C<ev_prepare> watcher.	2102	and unblock them in an C<ev_prepare> watcher.
2050		2103
2051	=head3 Watcher-Specific Functions and Data Members	2104	=head3 Watcher-Specific Functions and Data Members
2052		2105
2053	=over 4	2106	=over 4
2054		2107
…		…
2099	libev)	2152	libev)
2100		2153
2101	=head3 Process Interaction	2154	=head3 Process Interaction
2102		2155
2103	Libev grabs C<SIGCHLD> as soon as the default event loop is	2156	Libev grabs C<SIGCHLD> as soon as the default event loop is
2104	initialised. This is necessary to guarantee proper behaviour even if	2157	initialised. This is necessary to guarantee proper behaviour even if the
2105	the first child watcher is started after the child exits. The occurrence	2158	first child watcher is started after the child exits. The occurrence
2106	of C<SIGCHLD> is recorded asynchronously, but child reaping is done	2159	of C<SIGCHLD> is recorded asynchronously, but child reaping is done
2107	synchronously as part of the event loop processing. Libev always reaps all	2160	synchronously as part of the event loop processing. Libev always reaps all
2108	children, even ones not watched.	2161	children, even ones not watched.
2109		2162
2110	=head3 Overriding the Built-In Processing	2163	=head3 Overriding the Built-In Processing
…		…
2120	=head3 Stopping the Child Watcher	2173	=head3 Stopping the Child Watcher
2121		2174
2122	Currently, the child watcher never gets stopped, even when the	2175	Currently, the child watcher never gets stopped, even when the
2123	child terminates, so normally one needs to stop the watcher in the	2176	child terminates, so normally one needs to stop the watcher in the
2124	callback. Future versions of libev might stop the watcher automatically	2177	callback. Future versions of libev might stop the watcher automatically
2125	when a child exit is detected.	2178	when a child exit is detected (calling C<ev_child_stop> twice is not a
		2179	problem).
2126		2180
2127	=head3 Watcher-Specific Functions and Data Members	2181	=head3 Watcher-Specific Functions and Data Members
2128		2182
2129	=over 4	2183	=over 4
2130		2184
…		…
4028	}	4082	}
4029		4083
4030	Instead of invoking all pending watchers, the C<l_invoke> callback will	4084	Instead of invoking all pending watchers, the C<l_invoke> callback will
4031	signal the main thread via some unspecified mechanism (signals? pipe	4085	signal the main thread via some unspecified mechanism (signals? pipe
4032	writes? C<Async::Interrupt>?) and then waits until all pending watchers	4086	writes? C<Async::Interrupt>?) and then waits until all pending watchers
4033	have been called:	4087	have been called (in a while loop because a) spurious wakeups are possible
		4088	and b) skipping inter-thread-communication when there are no pending
		4089	watchers is very beneficial):
4034		4090
4035	static void	4091	static void
4036	l_invoke (EV_P)	4092	l_invoke (EV_P)
4037	{	4093	{
4038	userdata *u = ev_userdata (EV_A);	4094	userdata *u = ev_userdata (EV_A);
4039		4095
		4096	while (ev_pending_count (EV_A))
		4097	{
4040	wake_up_other_thread_in_some_magic_or_not_so_magic_way ();	4098	wake_up_other_thread_in_some_magic_or_not_so_magic_way ();
4041
4042	pthread_cond_wait (&u->invoke_cv, &u->lock);	4099	pthread_cond_wait (&u->invoke_cv, &u->lock);
		4100	}
4043	}	4101	}
4044		4102
4045	Now, whenever the main thread gets told to invoke pending watchers, it	4103	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	4104	will grab the lock, call C<ev_invoke_pending> and then signal the loop
4047	thread to continue:	4105	thread to continue:

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Comparing libev/ev.pod (file contents): Revision 1.255 by root, Tue Jul 14 19:11:31 2009 UTC vs. Revision 1.259 by root, Sun Jul 19 01:36:34 2009 UTC

Diff Legend

Comparing libev/ev.pod (file contents):
Revision 1.255 by root, Tue Jul 14 19:11:31 2009 UTC vs.
Revision 1.259 by root, Sun Jul 19 01:36:34 2009 UTC