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

Comparing libev/ev.pod (file contents):
Revision 1.254 by root, Tue Jul 14 19:02:43 2009 UTC vs.
Revision 1.260 by root, Sun Jul 19 21:18:03 2009 UTC

…		…
362	flag.	362	flag.
363		363
364	This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS>	364	This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS>
365	environment variable.	365	environment variable.
366		366
		367	=item C<EVFLAG_NOINOTIFY>
		368
		369	When this flag is specified, then libev will not attempt to use the
		370	I<inotify> API for it's C<ev_stat> watchers. Apart from debugging and
		371	testing, this flag can be useful to conserve inotify file descriptors, as
		372	otherwise each loop using C<ev_stat> watchers consumes one inotify handle.
		373
		374	=item C<EVFLAG_NOSIGNALFD>
		375
		376	When this flag is specified, then libev will not attempt to use the
		377	I<signalfd> API for it's C<ev_signal> (and C<ev_child>) watchers. This is
		378	probably only useful to work around any bugs in libev. Consequently, this
		379	flag might go away once the signalfd functionality is considered stable,
		380	so it's useful mostly in environment variables and not in program code.
		381
367	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	382	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
368		383
369	This is your standard select(2) backend. Not I<completely> standard, as	384	This is your standard select(2) backend. Not I<completely> standard, as
370	libev tries to roll its own fd_set with no limits on the number of fds,	385	libev tries to roll its own fd_set with no limits on the number of fds,
371	but if that fails, expect a fairly low limit on the number of fds when	386	but if that fails, expect a fairly low limit on the number of fds when
…		…
518		533
519	It is definitely not recommended to use this flag.	534	It is definitely not recommended to use this flag.
520		535
521	=back	536	=back
522		537
523	If one or more of these are or'ed into the flags value, then only these	538	If one or more of the backend flags are or'ed into the flags value,
524	backends will be tried (in the reverse order as listed here). If none are	539	then only these backends will be tried (in the reverse order as listed
525	specified, all backends in C<ev_recommended_backends ()> will be tried.	540	here). If none are specified, all backends in C<ev_recommended_backends
		541	()> will be tried.
526		542
527	Example: This is the most typical usage.	543	Example: This is the most typical usage.
528		544
529	if (!ev_default_loop (0))	545	if (!ev_default_loop (0))
530	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");	546	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
…		…
862		878
863	This call will simply invoke all pending watchers while resetting their	879	This call will simply invoke all pending watchers while resetting their
864	pending state. Normally, C<ev_loop> does this automatically when required,	880	pending state. Normally, C<ev_loop> does this automatically when required,
865	but when overriding the invoke callback this call comes handy.	881	but when overriding the invoke callback this call comes handy.
866		882
		883	=item int ev_pending_count (loop)
		884
		885	Returns the number of pending watchers - zero indicates that no watchers
		886	are pending.
		887
867	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))	888	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))
868		889
869	This overrides the invoke pending functionality of the loop: Instead of	890	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	891	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	892	this callback instead. This is useful, for example, when you want to
…		…
1750		1771
1751	If the event loop is suspended for a long time, you can also force an	1772	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	1773	update of the time returned by C<ev_now ()> by calling C<ev_now_update
1753	()>.	1774	()>.
1754		1775
		1776	=head3 The special problems of suspended animation
		1777
		1778	When you leave the server world it is quite customary to hit machines that
		1779	can suspend/hibernate - what happens to the clocks during such a suspend?
		1780
		1781	Some quick tests made with a Linux 2.6.28 indicate that a suspend freezes
		1782	all processes, while the clocks (C<times>, C<CLOCK_MONOTONIC>) continue
		1783	to run until the system is suspended, but they will not advance while the
		1784	system is suspended. That means, on resume, it will be as if the program
		1785	was frozen for a few seconds, but the suspend time will not be counted
		1786	towards C<ev_timer> when a monotonic clock source is used. The real time
		1787	clock advanced as expected, but if it is used as sole clocksource, then a
		1788	long suspend would be detected as a time jump by libev, and timers would
		1789	be adjusted accordingly.
		1790
		1791	I would not be surprised to see different behaviour in different between
		1792	operating systems, OS versions or even different hardware.
		1793
		1794	The other form of suspend (job control, or sending a SIGSTOP) will see a
		1795	time jump in the monotonic clocks and the realtime clock. If the program
		1796	is suspended for a very long time, and monotonic clock sources are in use,
		1797	then you can expect C<ev_timer>s to expire as the full suspension time
		1798	will be counted towards the timers. When no monotonic clock source is in
		1799	use, then libev will again assume a timejump and adjust accordingly.
		1800
		1801	It might be beneficial for this latter case to call C<ev_suspend>
		1802	and C<ev_resume> in code that handles C<SIGTSTP>, to at least get
		1803	deterministic behaviour in this case (you can do nothing against
		1804	C<SIGSTOP>).
		1805
1755	=head3 Watcher-Specific Functions and Data Members	1806	=head3 Watcher-Specific Functions and Data Members
1756		1807
1757	=over 4	1808	=over 4
1758		1809
1759	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	1810	=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	1835	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.	1836	C<repeat> value), or reset the running timer to the C<repeat> value.
1786		1837
1787	This sounds a bit complicated, see L<Be smart about timeouts>, above, for a	1838	This sounds a bit complicated, see L<Be smart about timeouts>, above, for a
1788	usage example.	1839	usage example.
		1840
		1841	=item ev_timer_remaining (loop, ev_timer *)
		1842
		1843	Returns the remaining time until a timer fires. If the timer is active,
		1844	then this time is relative to the current event loop time, otherwise it's
		1845	the timeout value currently configured.
		1846
		1847	That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns
		1848	C<5>. When the timer is started and one second passes, C<ev_timer_remain>
		1849	will return C<4>. When the timer expires and is restarted, it will return
		1850	roughly C<7> (likely slightly less as callback invocation takes some time,
		1851	too), and so on.
1789		1852
1790	=item ev_tstamp repeat [read-write]	1853	=item ev_tstamp repeat [read-write]
1791		1854
1792	The current C<repeat> value. Will be used each time the watcher times out	1855	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),	1856	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	2092	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	2093	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	2094	will try it's best to deliver signals synchronously, i.e. as part of the
2032	normal event processing, like any other event.	2095	normal event processing, like any other event.
2033		2096
2034	If you want signals asynchronously, just use C<sigaction> as you would	2097	If you want signals to be delivered truly asynchronously, just use
2035	do without libev and forget about sharing the signal. You can even use	2098	C<sigaction> as you would do without libev and forget about sharing
2036	C<ev_async> from a signal handler to synchronously wake up an event loop.	2099	the signal. You can even use C<ev_async> from a signal handler to
		2100	synchronously wake up an event loop.
2037		2101
2038	You can configure as many watchers as you like per signal. Only when the	2102	You can configure as many watchers as you like for the same signal, but
		2103	only within the same loop, i.e. you can watch for C<SIGINT> in your
		2104	default loop and for C<SIGIO> in another loop, but you cannot watch for
		2105	C<SIGINT> in both the default loop and another loop at the same time. At
		2106	the moment, C<SIGCHLD> is permanently tied to the default loop.
		2107
2039	first watcher gets started will libev actually register a signal handler	2108	When the first watcher gets started will libev actually register something
2040	with the kernel (thus it coexists with your own signal handlers as long as	2109	with the kernel (thus it coexists with your own signal handlers as long as
2041	you don't register any with libev for the same signal). Similarly, when	2110	you don't register any with libev for the same signal).
2042	the last signal watcher for a signal is stopped, libev will reset the	2111
2043	signal handler to SIG_DFL (regardless of what it was set to before).	2112	Both the signal mask state (C<sigprocmask>) and the signal handler state
		2113	(C<sigaction>) are unspecified after starting a signal watcher (and after
		2114	sotpping it again), that is, libev might or might not block the signal,
		2115	and might or might not set or restore the installed signal handler.
2044		2116
2045	If possible and supported, libev will install its handlers with	2117	If possible and supported, libev will install its handlers with
2046	C<SA_RESTART> behaviour enabled, so system calls should not be unduly	2118	C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should
2047	interrupted. If you have a problem with system calls getting interrupted by	2119	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	2120	interrupted by signals you can block all signals in an C<ev_check> watcher
2049	them in an C<ev_prepare> watcher.	2121	and unblock them in an C<ev_prepare> watcher.
2050		2122
2051	=head3 Watcher-Specific Functions and Data Members	2123	=head3 Watcher-Specific Functions and Data Members
2052		2124
2053	=over 4	2125	=over 4
2054		2126
…		…
2099	libev)	2171	libev)
2100		2172
2101	=head3 Process Interaction	2173	=head3 Process Interaction
2102		2174
2103	Libev grabs C<SIGCHLD> as soon as the default event loop is	2175	Libev grabs C<SIGCHLD> as soon as the default event loop is
2104	initialised. This is necessary to guarantee proper behaviour even if	2176	initialised. This is necessary to guarantee proper behaviour even if the
2105	the first child watcher is started after the child exits. The occurrence	2177	first child watcher is started after the child exits. The occurrence
2106	of C<SIGCHLD> is recorded asynchronously, but child reaping is done	2178	of C<SIGCHLD> is recorded asynchronously, but child reaping is done
2107	synchronously as part of the event loop processing. Libev always reaps all	2179	synchronously as part of the event loop processing. Libev always reaps all
2108	children, even ones not watched.	2180	children, even ones not watched.
2109		2181
2110	=head3 Overriding the Built-In Processing	2182	=head3 Overriding the Built-In Processing
…		…
2120	=head3 Stopping the Child Watcher	2192	=head3 Stopping the Child Watcher
2121		2193
2122	Currently, the child watcher never gets stopped, even when the	2194	Currently, the child watcher never gets stopped, even when the
2123	child terminates, so normally one needs to stop the watcher in the	2195	child terminates, so normally one needs to stop the watcher in the
2124	callback. Future versions of libev might stop the watcher automatically	2196	callback. Future versions of libev might stop the watcher automatically
2125	when a child exit is detected.	2197	when a child exit is detected (calling C<ev_child_stop> twice is not a
		2198	problem).
2126		2199
2127	=head3 Watcher-Specific Functions and Data Members	2200	=head3 Watcher-Specific Functions and Data Members
2128		2201
2129	=over 4	2202	=over 4
2130		2203
…		…
3745	Defining C<EV_MINIMAL> to C<2> will additionally reduce the core API to	3818	Defining C<EV_MINIMAL> to C<2> will additionally reduce the core API to
3746	provide a bare-bones event library. See C<ev.h> for details on what parts	3819	provide a bare-bones event library. See C<ev.h> for details on what parts
3747	of the API are still available, and do not complain if this subset changes	3820	of the API are still available, and do not complain if this subset changes
3748	over time.	3821	over time.
3749		3822
		3823	=item EV_NSIG
		3824
		3825	The highest supported signal number, +1 (or, the number of
		3826	signals): Normally, libev tries to deduce the maximum number of signals
		3827	automatically, but sometimes this fails, in which case it can be
		3828	specified. Also, using a lower number than detected (C<32> should be
		3829	good for about any system in existance) can save some memory, as libev
		3830	statically allocates some 12-24 bytes per signal number.
		3831
3750	=item EV_PID_HASHSIZE	3832	=item EV_PID_HASHSIZE
3751		3833
3752	C<ev_child> watchers use a small hash table to distribute workload by	3834	C<ev_child> watchers use a small hash table to distribute workload by
3753	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more	3835	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more
3754	than enough. If you need to manage thousands of children you might want to	3836	than enough. If you need to manage thousands of children you might want to
…		…
3998	protecting the loop data, respectively.	4080	protecting the loop data, respectively.
3999		4081
4000	static void	4082	static void
4001	l_release (EV_P)	4083	l_release (EV_P)
4002	{	4084	{
4003	udat *u = ev_userdata (EV_A);	4085	userdata *u = ev_userdata (EV_A);
4004	pthread_mutex_unlock (&u->lock);	4086	pthread_mutex_unlock (&u->lock);
4005	}	4087	}
4006		4088
4007	static void	4089	static void
4008	l_acquire (EV_P)	4090	l_acquire (EV_P)
4009	{	4091	{
4010	udat *u = ev_userdata (EV_A);	4092	userdata *u = ev_userdata (EV_A);
4011	pthread_mutex_lock (&u->lock);	4093	pthread_mutex_lock (&u->lock);
4012	}	4094	}
4013		4095
4014	The event loop thread first acquires the mutex, and then jumps straight	4096	The event loop thread first acquires the mutex, and then jumps straight
4015	into C<ev_loop>:	4097	into C<ev_loop>:
…		…
4028	}	4110	}
4029		4111
4030	Instead of invoking all pending watchers, the C<l_invoke> callback will	4112	Instead of invoking all pending watchers, the C<l_invoke> callback will
4031	signal the main thread via some unspecified mechanism (signals? pipe	4113	signal the main thread via some unspecified mechanism (signals? pipe
4032	writes? C<Async::Interrupt>?) and then waits until all pending watchers	4114	writes? C<Async::Interrupt>?) and then waits until all pending watchers
4033	have been called:	4115	have been called (in a while loop because a) spurious wakeups are possible
		4116	and b) skipping inter-thread-communication when there are no pending
		4117	watchers is very beneficial):
4034		4118
4035	static void	4119	static void
4036	l_invoke (EV_P)	4120	l_invoke (EV_P)
4037	{	4121	{
4038	udat *u = ev_userdata (EV_A);	4122	userdata *u = ev_userdata (EV_A);
4039		4123
		4124	while (ev_pending_count (EV_A))
		4125	{
4040	wake_up_other_thread_in_some_magic_or_not_so_magic_way ();	4126	wake_up_other_thread_in_some_magic_or_not_so_magic_way ();
4041
4042	pthread_cond_wait (&u->invoke_cv, &u->lock);	4127	pthread_cond_wait (&u->invoke_cv, &u->lock);
		4128	}
4043	}	4129	}
4044		4130
4045	Now, whenever the main thread gets told to invoke pending watchers, it	4131	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	4132	will grab the lock, call C<ev_invoke_pending> and then signal the loop
4047	thread to continue:	4133	thread to continue:
4048		4134
4049	static void	4135	static void
4050	real_invoke_pending (EV_P)	4136	real_invoke_pending (EV_P)
4051	{	4137	{
4052	udat *u = ev_userdata (EV_A);	4138	userdata *u = ev_userdata (EV_A);
4053		4139
4054	pthread_mutex_lock (&u->lock);	4140	pthread_mutex_lock (&u->lock);
4055	ev_invoke_pending (EV_A);	4141	ev_invoke_pending (EV_A);
4056	pthread_cond_signal (&u->invoke_cv);	4142	pthread_cond_signal (&u->invoke_cv);
4057	pthread_mutex_unlock (&u->lock);	4143	pthread_mutex_unlock (&u->lock);
…		…
4059		4145
4060	Whenever you want to start/stop a watcher or do other modifications to an	4146	Whenever you want to start/stop a watcher or do other modifications to an
4061	event loop, you will now have to lock:	4147	event loop, you will now have to lock:
4062		4148
4063	ev_timer timeout_watcher;	4149	ev_timer timeout_watcher;
4064	udat *u = ev_userdata (EV_A);	4150	userdata *u = ev_userdata (EV_A);
4065		4151
4066	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);	4152	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
4067		4153
4068	pthread_mutex_lock (&u->lock);	4154	pthread_mutex_lock (&u->lock);
4069	ev_timer_start (EV_A_ &timeout_watcher);	4155	ev_timer_start (EV_A_ &timeout_watcher);
…		…
4078	=head3 COROUTINES	4164	=head3 COROUTINES
4079		4165
4080	Libev is very accommodating to coroutines ("cooperative threads"):	4166	Libev is very accommodating to coroutines ("cooperative threads"):
4081	libev fully supports nesting calls to its functions from different	4167	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	4168	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	4169	different coroutines, and switch freely between both coroutines running
4084	loop, as long as you don't confuse yourself). The only exception is that	4170	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.	4171	that you must not do this from C<ev_periodic> reschedule callbacks.
4086		4172
4087	Care has been taken to ensure that libev does not keep local state inside	4173	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	4174	C<ev_loop>, and other calls do not usually allow for coroutine switches as
4089	they do not call any callbacks.	4175	they do not call any callbacks.
4090		4176

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Comparing libev/ev.pod (file contents): Revision 1.254 by root, Tue Jul 14 19:02:43 2009 UTC vs. Revision 1.260 by root, Sun Jul 19 21:18:03 2009 UTC

Diff Legend

Comparing libev/ev.pod (file contents):
Revision 1.254 by root, Tue Jul 14 19:02:43 2009 UTC vs.
Revision 1.260 by root, Sun Jul 19 21:18:03 2009 UTC