[ViewVC] Diff of: cvs/cvsroot/Coro/Coro.pm

Comparing cvsroot/Coro/Coro.pm (file contents):
Revision 1.268 by root, Thu Oct 1 23:16:27 2009 UTC vs.
Revision 1.296 by root, Thu May 12 23:24:28 2011 UTC

…		…
40	points in your program, so locking and parallel access are rarely an	40	points in your program, so locking and parallel access are rarely an
41	issue, making thread programming much safer and easier than using other	41	issue, making thread programming much safer and easier than using other
42	thread models.	42	thread models.
43		43
44	Unlike the so-called "Perl threads" (which are not actually real threads	44	Unlike the so-called "Perl threads" (which are not actually real threads
45	but only the windows process emulation (see section of same name for more	45	but only the windows process emulation (see section of same name for
46	details) ported to unix, and as such act as processes), Coro provides	46	more details) ported to UNIX, and as such act as processes), Coro
47	a full shared address space, which makes communication between threads	47	provides a full shared address space, which makes communication between
48	very easy. And Coro's threads are fast, too: disabling the Windows	48	threads very easy. And coro threads are fast, too: disabling the Windows
49	process emulation code in your perl and using Coro can easily result in	49	process emulation code in your perl and using Coro can easily result in
50	a two to four times speed increase for your programs. A parallel matrix	50	a two to four times speed increase for your programs. A parallel matrix
51	multiplication benchmark runs over 300 times faster on a single core than	51	multiplication benchmark (very communication-intensive) runs over 300
52	perl's pseudo-threads on a quad core using all four cores.	52	times faster on a single core than perls pseudo-threads on a quad core
		53	using all four cores.
53		54
54	Coro achieves that by supporting multiple running interpreters that share	55	Coro achieves that by supporting multiple running interpreters that share
55	data, which is especially useful to code pseudo-parallel processes and	56	data, which is especially useful to code pseudo-parallel processes and
56	for event-based programming, such as multiple HTTP-GET requests running	57	for event-based programming, such as multiple HTTP-GET requests running
57	concurrently. See L<Coro::AnyEvent> to learn more on how to integrate Coro	58	concurrently. See L<Coro::AnyEvent> to learn more on how to integrate Coro
…		…
63	variables (see L<Coro::State> for more configuration and background info).	64	variables (see L<Coro::State> for more configuration and background info).
64		65
65	See also the C<SEE ALSO> section at the end of this document - the Coro	66	See also the C<SEE ALSO> section at the end of this document - the Coro
66	module family is quite large.	67	module family is quite large.
67		68
		69	=head1 CORO THREAD LIFE CYCLE
		70
		71	During the long and exciting (or not) life of a coro thread, it goes
		72	through a number of states:
		73
		74	=over 4
		75
		76	=item 1. Creation
		77
		78	The first thing in the life of a coro thread is it's creation -
		79	obviously. The typical way to create a thread is to call the C<async
		80	BLOCK> function:
		81
		82	async {
		83	# thread code goes here
		84	};
		85
		86	You can also pass arguments, which are put in C<@_>:
		87
		88	async {
		89	print $_[1]; # prints 2
		90	} 1, 2, 3;
		91
		92	This creates a new coro thread and puts it into the ready queue, meaning
		93	it will run as soon as the CPU is free for it.
		94
		95	C<async> will return a coro object - you can store this for future
		96	reference or ignore it, the thread itself will keep a reference to it's
		97	thread object - threads are alive on their own.
		98
		99	Another way to create a thread is to call the C<new> constructor with a
		100	code-reference:
		101
		102	new Coro sub {
		103	# thread code goes here
		104	}, @optional_arguments;
		105
		106	This is quite similar to calling C<async>, but the important difference is
		107	that the new thread is not put into the ready queue, so the thread will
		108	not run until somebody puts it there. C<async> is, therefore, identical to
		109	this sequence:
		110
		111	my $coro = new Coro sub {
		112	# thread code goes here
		113	};
		114	$coro->ready;
		115	return $coro;
		116
		117	=item 2. Startup
		118
		119	When a new coro thread is created, only a copy of the code reference
		120	and the arguments are stored, no extra memory for stacks and so on is
		121	allocated, keeping the coro thread in a low-memory state.
		122
		123	Only when it actually starts executing will all the resources be finally
		124	allocated.
		125
		126	The optional arguments specified at coro creation are available in C<@_>,
		127	similar to function calls.
		128
		129	=item 3. Running / Blocking
		130
		131	A lot can happen after the coro thread has started running. Quite usually,
		132	it will not run to the end in one go (because you could use a function
		133	instead), but it will give up the CPU regularly because it waits for
		134	external events.
		135
		136	As long as a coro thread runs, it's coro object is available in the global
		137	variable C<$Coro::current>.
		138
		139	The low-level way to give up the CPU is to call the scheduler, which
		140	selects a new coro thread to run:
		141
		142	Coro::schedule;
		143
		144	Since running threads are not in the ready queue, calling the scheduler
		145	without doing anything else will block the coro thread forever - you need
		146	to arrange either for the coro to put woken up (readied) by some other
		147	event or some other thread, or you can put it into the ready queue before
		148	scheduling:
		149
		150	# this is exactly what Coro::cede does
		151	$Coro::current->ready;
		152	Coro::schedule;
		153
		154	All the higher-level synchronisation methods (Coro::Semaphore,
		155	Coro::rouse_*...) are actually implemented via C<< ->ready >> and C<<
		156	Coro::schedule >>.
		157
		158	While the coro thread is running it also might get assigned a C-level
		159	thread, or the C-level thread might be unassigned from it, as the Coro
		160	runtime wishes. A C-level thread needs to be assigned when your perl
		161	thread calls into some C-level function and that function in turn calls
		162	perl and perl then wants to switch coroutines. This happens most often
		163	when you run an event loop and block in the callback, or when perl
		164	itself calls some function such as C<AUTOLOAD> or methods via the C<tie>
		165	mechanism.
		166
		167	=item 4. Termination
		168
		169	Many threads actually terminate after some time. There are a number of
		170	ways to terminate a coro thread, the simplest is returning from the
		171	top-level code reference:
		172
		173	async {
		174	# after returning from here, the coro thread is terminated
		175	};
		176
		177	async {
		178	return if 0.5 < rand; # terminate a little earlier, maybe
		179	print "got a chance to print this\n";
		180	# or here
		181	};
		182
		183	Any values returned from the coroutine can be recovered using C<< ->join
		184	>>:
		185
		186	my $coro = async {
		187	"hello, world\n" # return a string
		188	};
		189
		190	my $hello_world = $coro->join;
		191
		192	print $hello_world;
		193
		194	Another way to terminate is to call C<< Coro::terminate >>, which at any
		195	subroutine call nesting level:
		196
		197	async {
		198	Coro::terminate "return value 1", "return value 2";
		199	};
		200
		201	And yet another way is to C<< ->cancel >> (or C<< ->safe_cancel >>) the
		202	coro thread from another thread:
		203
		204	my $coro = async {
		205	exit 1;
		206	};
		207
		208	$coro->cancel; # also accepts values for ->join to retrieve
		209
		210	Cancellation I<can> be dangerous - it's a bit like calling C<exit> without
		211	actually exiting, and might leave C libraries and XS modules in a weird
		212	state. Unlike other thread implementations, however, Coro is exceptionally
		213	safe with regards to cancellation, as perl will always be in a consistent
		214	state, and for those cases where you want to do truly marvellous things
		215	with your coro while it is being cancelled - that is, make sure all
		216	cleanup code is executed from the thread being cancelled - there is even a
		217	C<< ->safe_cancel >> method.
		218
		219	So, cancelling a thread that runs in an XS event loop might not be the
		220	best idea, but any other combination that deals with perl only (cancelling
		221	when a thread is in a C<tie> method or an C<AUTOLOAD> for example) is
		222	safe.
		223
		224	=item 5. Cleanup
		225
		226	Threads will allocate various resources. Most but not all will be returned
		227	when a thread terminates, during clean-up.
		228
		229	Cleanup is quite similar to throwing an uncaught exception: perl will
		230	work it's way up through all subroutine calls and blocks. On it's way, it
		231	will release all C<my> variables, undo all C<local>'s and free any other
		232	resources truly local to the thread.
		233
		234	So, a common way to free resources is to keep them referenced only by my
		235	variables:
		236
		237	async {
		238	my $big_cache = new Cache ...;
		239	};
		240
		241	If there are no other references, then the C<$big_cache> object will be
		242	freed when the thread terminates, regardless of how it does so.
		243
		244	What it does C<NOT> do is unlock any Coro::Semaphores or similar
		245	resources, but that's where the C<guard> methods come in handy:
		246
		247	my $sem = new Coro::Semaphore;
		248
		249	async {
		250	my $lock_guard = $sem->guard;
		251	# if we reutrn, or die or get cancelled, here,
		252	# then the semaphore will be "up"ed.
		253	};
		254
		255	The C<Guard::guard> function comes in handy for any custom cleanup you
		256	might want to do:
		257
		258	async {
		259	my $window = new Gtk2::Window "toplevel";
		260	# The window will not be cleaned up automatically, even when $window
		261	# gets freed, so use a guard to ensure it's destruction
		262	# in case of an error:
		263	my $window_guard = Guard::guard { $window->destroy };
		264
		265	# we are safe here
		266	};
		267
		268	Last not least, C<local> can often be handy, too, e.g. when temporarily
		269	replacing the coro thread description:
		270
		271	sub myfunction {
		272	local $Coro::current->{desc} = "inside myfunction(@_)";
		273
		274	# if we return or die here, the description will be restored
		275	}
		276
		277	=item 6. Viva La Zombie Muerte
		278
		279	Even after a thread has terminated and cleaned up it's resources, the coro
		280	object still is there and stores the return values of the thread. Only in
		281	this state will the coro object be "reference counted" in the normal perl
		282	sense: the thread code keeps a reference to it when it is active, but not
		283	after it has terminated.
		284
		285	The means the coro object gets freed automatically when the thread has
		286	terminated and cleaned up and there arenot other references.
		287
		288	If there are, the coro object will stay around, and you can call C<<
		289	->join >> as many times as you wish to retrieve the result values:
		290
		291	async {
		292	print "hi\n";
		293	1
		294	};
		295
		296	# run the async above, and free everything before returning
		297	# from Coro::cede:
		298	Coro::cede;
		299
		300	{
		301	my $coro = async {
		302	print "hi\n";
		303	1
		304	};
		305
		306	# run the async above, and clean up, but do not free the coro
		307	# object:
		308	Coro::cede;
		309
		310	# optionally retrieve the result values
		311	my @results = $coro->join;
		312
		313	# now $coro goes out of scope, and presumably gets freed
		314	};
		315
		316	=back
		317
68	=cut	318	=cut
69		319
70	package Coro;	320	package Coro;
71		321
72	use common::sense;	322	use common::sense;
…		…
81		331
82	our $idle; # idle handler	332	our $idle; # idle handler
83	our $main; # main coro	333	our $main; # main coro
84	our $current; # current coro	334	our $current; # current coro
85		335
86	our $VERSION = 5.17;	336	our $VERSION = 5.372;
87		337
88	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);	338	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub rouse_cb rouse_wait);
89	our %EXPORT_TAGS = (	339	our %EXPORT_TAGS = (
90	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	340	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
91	);	341	);
92	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));	342	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
93		343
…		…
124		374
125	This variable is mainly useful to integrate Coro into event loops. It is	375	This variable is mainly useful to integrate Coro into event loops. It is
126	usually better to rely on L<Coro::AnyEvent> or L<Coro::EV>, as this is	376	usually better to rely on L<Coro::AnyEvent> or L<Coro::EV>, as this is
127	pretty low-level functionality.	377	pretty low-level functionality.
128		378
129	This variable stores either a Coro object or a callback.	379	This variable stores a Coro object that is put into the ready queue when
		380	there are no other ready threads (without invoking any ready hooks).
130		381
131	If it is a callback, the it is called whenever the scheduler finds no	382	The default implementation dies with "FATAL: deadlock detected.", followed
132	ready coros to run. The default implementation prints "FATAL:	383	by a thread listing, because the program has no other way to continue.
133	deadlock detected" and exits, because the program has no other way to
134	continue.
135
136	If it is a coro object, then this object will be readied (without
137	invoking any ready hooks, however) when the scheduler finds no other ready
138	coros to run.
139		384
140	This hook is overwritten by modules such as C<Coro::EV> and	385	This hook is overwritten by modules such as C<Coro::EV> and
141	C<Coro::AnyEvent> to wait on an external event that hopefully wake up a	386	C<Coro::AnyEvent> to wait on an external event that hopefully wakes up a
142	coro so the scheduler can run it.	387	coro so the scheduler can run it.
143		388
144	Note that the callback I<must not>, under any circumstances, block
145	the current coro. Normally, this is achieved by having an "idle
146	coro" that calls the event loop and then blocks again, and then
147	readying that coro in the idle handler, or by simply placing the idle
148	coro in this variable.
149
150	See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this	389	See L<Coro::EV> or L<Coro::AnyEvent> for examples of using this technique.
151	technique.
152		390
153	Please note that if your callback recursively invokes perl (e.g. for event
154	handlers), then it must be prepared to be called recursively itself.
155
156	=cut	391	=cut
157		392
158	$idle = sub {	393	# \|\|= because other modules could have provided their own by now
159	warn "oi\n";#d#	394	$idle \|\|= new Coro sub {
160	Carp::confess ("FATAL: deadlock detected");	395	require Coro::Debug;
		396	die "FATAL: deadlock detected.\n"
		397	. Coro::Debug::ps_listing ();
161	};	398	};
162		399
163	# this coro is necessary because a coro	400	# this coro is necessary because a coro
164	# cannot destroy itself.	401	# cannot destroy itself.
165	our @destroy;	402	our @destroy;
166	our $manager;	403	our $manager;
167		404
168	$manager = new Coro sub {	405	$manager = new Coro sub {
169	while () {	406	while () {
170	Coro::State::cancel shift @destroy	407	_destroy shift @destroy
171	while @destroy;	408	while @destroy;
172		409
173	&schedule;	410	&schedule;
174	}	411	}
175	};	412	};
…		…
273	=item schedule	510	=item schedule
274		511
275	Calls the scheduler. The scheduler will find the next coro that is	512	Calls the scheduler. The scheduler will find the next coro that is
276	to be run from the ready queue and switches to it. The next coro	513	to be run from the ready queue and switches to it. The next coro
277	to be run is simply the one with the highest priority that is longest	514	to be run is simply the one with the highest priority that is longest
278	in its ready queue. If there is no coro ready, it will clal the	515	in its ready queue. If there is no coro ready, it will call the
279	C<$Coro::idle> hook.	516	C<$Coro::idle> hook.
280		517
281	Please note that the current coro will I<not> be put into the ready	518	Please note that the current coro will I<not> be put into the ready
282	queue, so calling this function usually means you will never be called	519	queue, so calling this function usually means you will never be called
283	again unless something else (e.g. an event handler) calls C<< ->ready >>,	520	again unless something else (e.g. an event handler) calls C<< ->ready >>,
…		…
309	coro, regardless of priority. This is useful sometimes to ensure	546	coro, regardless of priority. This is useful sometimes to ensure
310	progress is made.	547	progress is made.
311		548
312	=item terminate [arg...]	549	=item terminate [arg...]
313		550
314	Terminates the current coro with the given status values (see L<cancel>).	551	Terminates the current coro with the given status values (see
		552	L<cancel>). The values will not be copied, but referenced directly.
315		553
316	=item Coro::on_enter BLOCK, Coro::on_leave BLOCK	554	=item Coro::on_enter BLOCK, Coro::on_leave BLOCK
317		555
318	These function install enter and leave winders in the current scope. The	556	These function install enter and leave winders in the current scope. The
319	enter block will be executed when on_enter is called and whenever the	557	enter block will be executed when on_enter is called and whenever the
…		…
493	Returns true iff this Coro object has been suspended. Suspended Coros will	731	Returns true iff this Coro object has been suspended. Suspended Coros will
494	not ever be scheduled.	732	not ever be scheduled.
495		733
496	=item $coro->cancel (arg...)	734	=item $coro->cancel (arg...)
497		735
498	Terminates the given Coro and makes it return the given arguments as	736	Terminates the given Coro thread and makes it return the given arguments as
499	status (default: the empty list). Never returns if the Coro is the	737	status (default: an empty list). Never returns if the Coro is the
500	current Coro.	738	current Coro.
501		739
502	=cut	740	This is a rather brutal way to free a coro, with some limitations - if
		741	the thread is inside a C callback that doesn't expect to be canceled,
		742	bad things can happen, or if the cancelled thread insists on running
		743	complicated cleanup handlers that rely on it'S thread context, things will
		744	not work.
503		745
504	sub cancel {	746	Any cleanup code being run (e.g. from C<guard> blocks) will be run without
505	my $self = shift;	747	a thread context, and is not allowed to switch to other threads. On the
		748	plus side, C<< ->cancel >> will always clean up the thread, no matter
		749	what. If your cleanup code is complex or you want to avoid cancelling a
		750	C-thread that doesn't know how to clean up itself, it can be better to C<<
		751	->throw >> an exception, or use C<< ->safe_cancel >>.
506		752
507	if ($current == $self) {	753	The arguments to C<< ->cancel >> are not copied, but instead will
508	terminate @_;	754	be referenced directly (e.g. if you pass C<$var> and after the call
509	} else {	755	change that variable, then you might change the return values passed to
510	$self->{_status} = [@_];	756	e.g. C<join>, so don't do that).
511	Coro::State::cancel $self;	757
		758	The resources of the Coro are usually freed (or destructed) before this
		759	call returns, but this can be delayed for an indefinite amount of time, as
		760	in some cases the manager thread has to run first to actually destruct the
		761	Coro object.
		762
		763	=item $coro->safe_cancel ($arg...)
		764
		765	Works mostly like C<< ->cancel >>, but is inherently "safer", and
		766	consequently, can fail with an exception in cases the thread is not in a
		767	cancellable state.
		768
		769	This method works a bit like throwing an exception that cannot be caught
		770	- specifically, it will clean up the thread from within itself, so
		771	all cleanup handlers (e.g. C<guard> blocks) are run with full thread
		772	context and can block if they wish. The downside is that there is no
		773	guarantee that the thread can be cancelled when you call this method, and
		774	therefore, it might fail. It is also considerably slower than C<cancel> or
		775	C<terminate>.
		776
		777	A thread is in a safe-cancellable state if it either hasn't been run yet,
		778	or it has no C context attached and is inside an SLF function.
		779
		780	The latter two basically mean that the thread isn't currently inside a
		781	perl callback called from some C function (usually via some XS modules)
		782	and isn't currently executing inside some C function itself (via Coro's XS
		783	API).
		784
		785	This call returns true when it could cancel the thread, or croaks with an
		786	error otherwise (i.e. it either returns true or doesn't return at all).
		787
		788	Why the weird interface? Well, there are two common models on how and
		789	when to cancel things. In the first, you have the expectation that your
		790	coro thread can be cancelled when you want to cancel it - if the thread
		791	isn't cancellable, this would be a bug somewhere, so C<< ->safe_cancel >>
		792	croaks to notify of the bug.
		793
		794	In the second model you sometimes want to ask nicely to cancel a thread,
		795	but if it's not a good time, well, then don't cancel. This can be done
		796	relatively easy like this:
		797
		798	if (! eval { $coro->safe_cancel }) {
		799	warn "unable to cancel thread: $@";
512	}	800	}
513	}	801
		802	However, what you never should do is first try to cancel "safely" and
		803	if that fails, cancel the "hard" way with C<< ->cancel >>. That makes
		804	no sense: either you rely on being able to execute cleanup code in your
		805	thread context, or you don't. If you do, then C<< ->safe_cancel >> is the
		806	only way, and if you don't, then C<< ->cancel >> is always faster and more
		807	direct.
514		808
515	=item $coro->schedule_to	809	=item $coro->schedule_to
516		810
517	Puts the current coro to sleep (like C<Coro::schedule>), but instead	811	Puts the current coro to sleep (like C<Coro::schedule>), but instead
518	of continuing with the next coro from the ready queue, always switch to	812	of continuing with the next coro from the ready queue, always switch to
…		…
537	inside the coro at the next convenient point in time. Otherwise	831	inside the coro at the next convenient point in time. Otherwise
538	clears the exception object.	832	clears the exception object.
539		833
540	Coro will check for the exception each time a schedule-like-function	834	Coro will check for the exception each time a schedule-like-function
541	returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down	835	returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down
542	>>, C<< Coro::Handle->readable >> and so on. Most of these functions	836	>>, C<< Coro::Handle->readable >> and so on. Most of those functions (all
543	detect this case and return early in case an exception is pending.	837	that are part of Coro itself) detect this case and return early in case an
		838	exception is pending.
544		839
545	The exception object will be thrown "as is" with the specified scalar in	840	The exception object will be thrown "as is" with the specified scalar in
546	C<$@>, i.e. if it is a string, no line number or newline will be appended	841	C<$@>, i.e. if it is a string, no line number or newline will be appended
547	(unlike with C<die>).	842	(unlike with C<die>).
548		843
549	This can be used as a softer means than C<cancel> to ask a coro to	844	This can be used as a softer means than either C<cancel> or C<safe_cancel
550	end itself, although there is no guarantee that the exception will lead to	845	>to ask a coro to end itself, although there is no guarantee that the
551	termination, and if the exception isn't caught it might well end the whole	846	exception will lead to termination, and if the exception isn't caught it
552	program.	847	might well end the whole program.
553		848
554	You might also think of C<throw> as being the moral equivalent of	849	You might also think of C<throw> as being the moral equivalent of
555	C<kill>ing a coro with a signal (in this case, a scalar).	850	C<kill>ing a coro with a signal (in this case, a scalar).
556		851
557	=item $coro->join	852	=item $coro->join
558		853
559	Wait until the coro terminates and return any values given to the	854	Wait until the coro terminates and return any values given to the
560	C<terminate> or C<cancel> functions. C<join> can be called concurrently	855	C<terminate> or C<cancel> functions. C<join> can be called concurrently
561	from multiple coro, and all will be resumed and given the status	856	from multiple threads, and all will be resumed and given the status
562	return once the C<$coro> terminates.	857	return once the C<$coro> terminates.
563		858
564	=cut	859	=cut
565		860
566	sub join {	861	sub xjoin {
567	my $self = shift;	862	my $self = shift;
568		863
569	unless ($self->{_status}) {	864	unless ($self->{_status}) {
570	my $current = $current;	865	my $current = $current;
571		866
…		…
575	};	870	};
576		871
577	&schedule while $current;	872	&schedule while $current;
578	}	873	}
579		874
580	wantarray ? @{$self->{_status}} : $self->{_status}[0];	875	wantarray ? @{$self->{_status}} : $self->{_status}[0]
581	}	876	}
582		877
583	=item $coro->on_destroy (\&cb)	878	=item $coro->on_destroy (\&cb)
584		879
585	Registers a callback that is called when this coro gets destroyed,	880	Registers a callback that is called when this coro thread gets destroyed,
586	but before it is joined. The callback gets passed the terminate arguments,	881	that is, after it's resources have been freed but before it is joined. The
		882	callback gets passed the terminate/cancel arguments, if any, and I<must
587	if any, and I<must not> die, under any circumstances.	883	not> die, under any circumstances.
588		884
589	=cut	885	There can be any number of C<on_destroy> callbacks per coro, and there is
		886	no way currently to remove a callback once added.
590		887
		888	=cut
		889
591	sub on_destroy {	890	sub xon_destroy {
592	my ($self, $cb) = @_;	891	my ($self, $cb) = @_;
593		892
594	push @{ $self->{_on_destroy} }, $cb;	893	push @{ $self->{_on_destroy} }, $cb;
595	}	894	}
596		895
597	=item $oldprio = $coro->prio ($newprio)	896	=item $oldprio = $coro->prio ($newprio)
598		897
599	Sets (or gets, if the argument is missing) the priority of the	898	Sets (or gets, if the argument is missing) the priority of the
600	coro. Higher priority coro get run before lower priority	899	coro thread. Higher priority coro get run before lower priority
601	coro. Priorities are small signed integers (currently -4 .. +3),	900	coros. Priorities are small signed integers (currently -4 .. +3),
602	that you can refer to using PRIO_xxx constants (use the import tag :prio	901	that you can refer to using PRIO_xxx constants (use the import tag :prio
603	to get then):	902	to get then):
604		903
605	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN	904	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
606	3 > 1 > 0 > -1 > -3 > -4	905	3 > 1 > 0 > -1 > -3 > -4
607		906
608	# set priority to HIGH	907	# set priority to HIGH
609	current->prio (PRIO_HIGH);	908	current->prio (PRIO_HIGH);
610		909
611	The idle coro ($Coro::idle) always has a lower priority than any	910	The idle coro thread ($Coro::idle) always has a lower priority than any
612	existing coro.	911	existing coro.
613		912
614	Changing the priority of the current coro will take effect immediately,	913	Changing the priority of the current coro will take effect immediately,
615	but changing the priority of coro in the ready queue (but not	914	but changing the priority of a coro in the ready queue (but not running)
616	running) will only take effect after the next schedule (of that	915	will only take effect after the next schedule (of that coro). This is a
617	coro). This is a bug that will be fixed in some future version.	916	bug that will be fixed in some future version.
618		917
619	=item $newprio = $coro->nice ($change)	918	=item $newprio = $coro->nice ($change)
620		919
621	Similar to C<prio>, but subtract the given value from the priority (i.e.	920	Similar to C<prio>, but subtract the given value from the priority (i.e.
622	higher values mean lower priority, just as in unix).	921	higher values mean lower priority, just as in UNIX's nice command).
623		922
624	=item $olddesc = $coro->desc ($newdesc)	923	=item $olddesc = $coro->desc ($newdesc)
625		924
626	Sets (or gets in case the argument is missing) the description for this	925	Sets (or gets in case the argument is missing) the description for this
627	coro. This is just a free-form string you can associate with a	926	coro thread. This is just a free-form string you can associate with a
628	coro.	927	coro.
629		928
630	This method simply sets the C<< $coro->{desc} >> member to the given	929	This method simply sets the C<< $coro->{desc} >> member to the given
631	string. You can modify this member directly if you wish.	930	string. You can modify this member directly if you wish, and in fact, this
		931	is often preferred to indicate major processing states that cna then be
		932	seen for example in a L<Coro::Debug> session:
		933
		934	sub my_long_function {
		935	local $Coro::current->{desc} = "now in my_long_function";
		936	...
		937	$Coro::current->{desc} = "my_long_function: phase 1";
		938	...
		939	$Coro::current->{desc} = "my_long_function: phase 2";
		940	...
		941	}
632		942
633	=cut	943	=cut
634		944
635	sub desc {	945	sub desc {
636	my $old = $_[0]{desc};	946	my $old = $_[0]{desc};
…		…
673	returning a new coderef. Unblocking means that calling the new coderef	983	returning a new coderef. Unblocking means that calling the new coderef
674	will return immediately without blocking, returning nothing, while the	984	will return immediately without blocking, returning nothing, while the
675	original code ref will be called (with parameters) from within another	985	original code ref will be called (with parameters) from within another
676	coro.	986	coro.
677		987
678	The reason this function exists is that many event libraries (such as the	988	The reason this function exists is that many event libraries (such as
679	venerable L<Event\|Event> module) are not thread-safe (a weaker form	989	the venerable L<Event\|Event> module) are not thread-safe (a weaker form
680	of reentrancy). This means you must not block within event callbacks,	990	of reentrancy). This means you must not block within event callbacks,
681	otherwise you might suffer from crashes or worse. The only event library	991	otherwise you might suffer from crashes or worse. The only event library
682	currently known that is safe to use without C<unblock_sub> is L<EV>.	992	currently known that is safe to use without C<unblock_sub> is L<EV> (but
		993	you might still run into deadlocks if all event loops are blocked).
		994
		995	Coro will try to catch you when you block in the event loop
		996	("FATAL:$Coro::IDLE blocked itself"), but this is just best effort and
		997	only works when you do not run your own event loop.
683		998
684	This function allows your callbacks to block by executing them in another	999	This function allows your callbacks to block by executing them in another
685	coro where it is safe to block. One example where blocking is handy	1000	coro where it is safe to block. One example where blocking is handy
686	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to	1001	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
687	disk, for example.	1002	disk, for example.
…		…
729	unshift @unblock_queue, [$cb, @_];	1044	unshift @unblock_queue, [$cb, @_];
730	$unblock_scheduler->ready;	1045	$unblock_scheduler->ready;
731	}	1046	}
732	}	1047	}
733		1048
734	=item $cb = Coro::rouse_cb	1049	=item $cb = rouse_cb
735		1050
736	Create and return a "rouse callback". That's a code reference that,	1051	Create and return a "rouse callback". That's a code reference that,
737	when called, will remember a copy of its arguments and notify the owner	1052	when called, will remember a copy of its arguments and notify the owner
738	coro of the callback.	1053	coro of the callback.
739		1054
740	See the next function.	1055	See the next function.
741		1056
742	=item @args = Coro::rouse_wait [$cb]	1057	=item @args = rouse_wait [$cb]
743		1058
744	Wait for the specified rouse callback (or the last one that was created in	1059	Wait for the specified rouse callback (or the last one that was created in
745	this coro).	1060	this coro).
746		1061
747	As soon as the callback is invoked (or when the callback was invoked	1062	As soon as the callback is invoked (or when the callback was invoked
…		…
753	See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example.	1068	See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example.
754		1069
755	=back	1070	=back
756		1071
757	=cut	1072	=cut
		1073
		1074	for my $module (qw(Channel RWLock Semaphore SemaphoreSet Signal Specific)) {
		1075	my $old = defined &{"Coro::$module\::new"} && \&{"Coro::$module\::new"};
		1076
		1077	*{"Coro::$module\::new"} = sub {
		1078	require "Coro/$module.pm";
		1079
		1080	# some modules have their new predefined in State.xs, some don't
		1081	*{"Coro::$module\::new"} = $old
		1082	if $old;
		1083
		1084	goto &{"Coro::$module\::new"};
		1085	};
		1086	}
758		1087
759	1;	1088	1;
760		1089
761	=head1 HOW TO WAIT FOR A CALLBACK	1090	=head1 HOW TO WAIT FOR A CALLBACK
762		1091
…		…
842	future to allow per-thread schedulers, but Coro::State does not yet allow	1171	future to allow per-thread schedulers, but Coro::State does not yet allow
843	this). I recommend disabling thread support and using processes, as having	1172	this). I recommend disabling thread support and using processes, as having
844	the windows process emulation enabled under unix roughly halves perl	1173	the windows process emulation enabled under unix roughly halves perl
845	performance, even when not used.	1174	performance, even when not used.
846		1175
		1176	Attempts to use threads created in another emulated process will crash
		1177	("cleanly", with a null pointer exception).
		1178
847	=item coro switching is not signal safe	1179	=item coro switching is not signal safe
848		1180
849	You must not switch to another coro from within a signal handler	1181	You must not switch to another coro from within a signal handler (only
850	(only relevant with %SIG - most event libraries provide safe signals).	1182	relevant with %SIG - most event libraries provide safe signals), I<unless>
		1183	you are sure you are not interrupting a Coro function.
851		1184
852	That means you I<MUST NOT> call any function that might "block" the	1185	That means you I<MUST NOT> call any function that might "block" the
853	current coro - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or	1186	current coro - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or
854	anything that calls those. Everything else, including calling C<ready>,	1187	anything that calls those. Everything else, including calling C<ready>,
855	works.	1188	works.
…		…
865	ithreads (for example, that memory or files would be shared), showing his	1198	ithreads (for example, that memory or files would be shared), showing his
866	lack of understanding of this area - if it is hard to understand for Chip,	1199	lack of understanding of this area - if it is hard to understand for Chip,
867	it is probably not obvious to everybody).	1200	it is probably not obvious to everybody).
868		1201
869	What follows is an ultra-condensed version of my talk about threads in	1202	What follows is an ultra-condensed version of my talk about threads in
870	scripting languages given onthe perl workshop 2009:	1203	scripting languages given on the perl workshop 2009:
871		1204
872	The so-called "ithreads" were originally implemented for two reasons:	1205	The so-called "ithreads" were originally implemented for two reasons:
873	first, to (badly) emulate unix processes on native win32 perls, and	1206	first, to (badly) emulate unix processes on native win32 perls, and
874	secondly, to replace the older, real thread model ("5.005-threads").	1207	secondly, to replace the older, real thread model ("5.005-threads").
875		1208

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Comparing cvsroot/Coro/Coro.pm (file contents): Revision 1.268 by root, Thu Oct 1 23:16:27 2009 UTC vs. Revision 1.296 by root, Thu May 12 23:24:28 2011 UTC

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Revision 1.296 by root, Thu May 12 23:24:28 2011 UTC