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

Comparing Coro/Coro.pm (file contents):
Revision 1.275 by root, Wed Mar 31 17:41:07 2010 UTC vs.
Revision 1.301 by root, Sun Jul 3 10:51:40 2011 UTC

…		…
16	cede; # yield to coro	16	cede; # yield to coro
17	print "3\n";	17	print "3\n";
18	cede; # and again	18	cede; # and again
19		19
20	# use locking	20	# use locking
21	use Coro::Semaphore;
22	my $lock = new Coro::Semaphore;	21	my $lock = new Coro::Semaphore;
23	my $locked;	22	my $locked;
24		23
25	$lock->down;	24	$lock->down;
26	$locked = 1;	25	$locked = 1;
…		…
40	points in your program, so locking and parallel access are rarely an	39	points in your program, so locking and parallel access are rarely an
41	issue, making thread programming much safer and easier than using other	40	issue, making thread programming much safer and easier than using other
42	thread models.	41	thread models.
43		42
44	Unlike the so-called "Perl threads" (which are not actually real threads	43	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	44	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	45	more details) ported to UNIX, and as such act as processes), Coro
47	a full shared address space, which makes communication between threads	46	provides a full shared address space, which makes communication between
48	very easy. And Coro's threads are fast, too: disabling the Windows	47	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	48	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	49	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	50	multiplication benchmark (very communication-intensive) runs over 300
52	perl's pseudo-threads on a quad core using all four cores.	51	times faster on a single core than perls pseudo-threads on a quad core
		52	using all four cores.
53		53
54	Coro achieves that by supporting multiple running interpreters that share	54	Coro achieves that by supporting multiple running interpreters that share
55	data, which is especially useful to code pseudo-parallel processes and	55	data, which is especially useful to code pseudo-parallel processes and
56	for event-based programming, such as multiple HTTP-GET requests running	56	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	57	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).	63	variables (see L<Coro::State> for more configuration and background info).
64		64
65	See also the C<SEE ALSO> section at the end of this document - the Coro	65	See also the C<SEE ALSO> section at the end of this document - the Coro
66	module family is quite large.	66	module family is quite large.
67		67
		68	=head1 CORO THREAD LIFE CYCLE
		69
		70	During the long and exciting (or not) life of a coro thread, it goes
		71	through a number of states:
		72
		73	=over 4
		74
		75	=item 1. Creation
		76
		77	The first thing in the life of a coro thread is it's creation -
		78	obviously. The typical way to create a thread is to call the C<async
		79	BLOCK> function:
		80
		81	async {
		82	# thread code goes here
		83	};
		84
		85	You can also pass arguments, which are put in C<@_>:
		86
		87	async {
		88	print $_[1]; # prints 2
		89	} 1, 2, 3;
		90
		91	This creates a new coro thread and puts it into the ready queue, meaning
		92	it will run as soon as the CPU is free for it.
		93
		94	C<async> will return a Coro object - you can store this for future
		95	reference or ignore it - a thread that is running, ready to run or waiting
		96	for some event is alive on it's own.
		97
		98	Another way to create a thread is to call the C<new> constructor with a
		99	code-reference:
		100
		101	new Coro sub {
		102	# thread code goes here
		103	}, @optional_arguments;
		104
		105	This is quite similar to calling C<async>, but the important difference is
		106	that the new thread is not put into the ready queue, so the thread will
		107	not run until somebody puts it there. C<async> is, therefore, identical to
		108	this sequence:
		109
		110	my $coro = new Coro sub {
		111	# thread code goes here
		112	};
		113	$coro->ready;
		114	return $coro;
		115
		116	=item 2. Startup
		117
		118	When a new coro thread is created, only a copy of the code reference
		119	and the arguments are stored, no extra memory for stacks and so on is
		120	allocated, keeping the coro thread in a low-memory state.
		121
		122	Only when it actually starts executing will all the resources be finally
		123	allocated.
		124
		125	The optional arguments specified at coro creation are available in C<@_>,
		126	similar to function calls.
		127
		128	=item 3. Running / Blocking
		129
		130	A lot can happen after the coro thread has started running. Quite usually,
		131	it will not run to the end in one go (because you could use a function
		132	instead), but it will give up the CPU regularly because it waits for
		133	external events.
		134
		135	As long as a coro thread runs, its Coro object is available in the global
		136	variable C<$Coro::current>.
		137
		138	The low-level way to give up the CPU is to call the scheduler, which
		139	selects a new coro thread to run:
		140
		141	Coro::schedule;
		142
		143	Since running threads are not in the ready queue, calling the scheduler
		144	without doing anything else will block the coro thread forever - you need
		145	to arrange either for the coro to put woken up (readied) by some other
		146	event or some other thread, or you can put it into the ready queue before
		147	scheduling:
		148
		149	# this is exactly what Coro::cede does
		150	$Coro::current->ready;
		151	Coro::schedule;
		152
		153	All the higher-level synchronisation methods (Coro::Semaphore,
		154	Coro::rouse_*...) are actually implemented via C<< ->ready >> and C<<
		155	Coro::schedule >>.
		156
		157	While the coro thread is running it also might get assigned a C-level
		158	thread, or the C-level thread might be unassigned from it, as the Coro
		159	runtime wishes. A C-level thread needs to be assigned when your perl
		160	thread calls into some C-level function and that function in turn calls
		161	perl and perl then wants to switch coroutines. This happens most often
		162	when you run an event loop and block in the callback, or when perl
		163	itself calls some function such as C<AUTOLOAD> or methods via the C<tie>
		164	mechanism.
		165
		166	=item 4. Termination
		167
		168	Many threads actually terminate after some time. There are a number of
		169	ways to terminate a coro thread, the simplest is returning from the
		170	top-level code reference:
		171
		172	async {
		173	# after returning from here, the coro thread is terminated
		174	};
		175
		176	async {
		177	return if 0.5 < rand; # terminate a little earlier, maybe
		178	print "got a chance to print this\n";
		179	# or here
		180	};
		181
		182	Any values returned from the coroutine can be recovered using C<< ->join
		183	>>:
		184
		185	my $coro = async {
		186	"hello, world\n" # return a string
		187	};
		188
		189	my $hello_world = $coro->join;
		190
		191	print $hello_world;
		192
		193	Another way to terminate is to call C<< Coro::terminate >>, which at any
		194	subroutine call nesting level:
		195
		196	async {
		197	Coro::terminate "return value 1", "return value 2";
		198	};
		199
		200	And yet another way is to C<< ->cancel >> (or C<< ->safe_cancel >>) the
		201	coro thread from another thread:
		202
		203	my $coro = async {
		204	exit 1;
		205	};
		206
		207	$coro->cancel; # also accepts values for ->join to retrieve
		208
		209	Cancellation I<can> be dangerous - it's a bit like calling C<exit> without
		210	actually exiting, and might leave C libraries and XS modules in a weird
		211	state. Unlike other thread implementations, however, Coro is exceptionally
		212	safe with regards to cancellation, as perl will always be in a consistent
		213	state, and for those cases where you want to do truly marvellous things
		214	with your coro while it is being cancelled - that is, make sure all
		215	cleanup code is executed from the thread being cancelled - there is even a
		216	C<< ->safe_cancel >> method.
		217
		218	So, cancelling a thread that runs in an XS event loop might not be the
		219	best idea, but any other combination that deals with perl only (cancelling
		220	when a thread is in a C<tie> method or an C<AUTOLOAD> for example) is
		221	safe.
		222
		223	Lastly, a coro thread object that isn't referenced is C<< ->cancel >>'ed
		224	automatically - just like other objects in Perl. This is not such a common
		225	case, however - a running thread is referencedy b C<$Coro::current>, a
		226	thread ready to run is referenced by the ready queue, a thread waiting
		227	on a lock or semaphore is referenced by being in some wait list and so
		228	on. But a thread that isn't in any of those queues gets cancelled:
		229
		230	async {
		231	schedule; # cede to other coros, don't go into the ready queue
		232	};
		233
		234	cede;
		235	# now the async above is destroyed, as it is not referenced by anything.
		236
		237	=item 5. Cleanup
		238
		239	Threads will allocate various resources. Most but not all will be returned
		240	when a thread terminates, during clean-up.
		241
		242	Cleanup is quite similar to throwing an uncaught exception: perl will
		243	work it's way up through all subroutine calls and blocks. On it's way, it
		244	will release all C<my> variables, undo all C<local>'s and free any other
		245	resources truly local to the thread.
		246
		247	So, a common way to free resources is to keep them referenced only by my
		248	variables:
		249
		250	async {
		251	my $big_cache = new Cache ...;
		252	};
		253
		254	If there are no other references, then the C<$big_cache> object will be
		255	freed when the thread terminates, regardless of how it does so.
		256
		257	What it does C<NOT> do is unlock any Coro::Semaphores or similar
		258	resources, but that's where the C<guard> methods come in handy:
		259
		260	my $sem = new Coro::Semaphore;
		261
		262	async {
		263	my $lock_guard = $sem->guard;
		264	# if we reutrn, or die or get cancelled, here,
		265	# then the semaphore will be "up"ed.
		266	};
		267
		268	The C<Guard::guard> function comes in handy for any custom cleanup you
		269	might want to do (but you cannot switch to other coroutines form those
		270	code blocks):
		271
		272	async {
		273	my $window = new Gtk2::Window "toplevel";
		274	# The window will not be cleaned up automatically, even when $window
		275	# gets freed, so use a guard to ensure it's destruction
		276	# in case of an error:
		277	my $window_guard = Guard::guard { $window->destroy };
		278
		279	# we are safe here
		280	};
		281
		282	Last not least, C<local> can often be handy, too, e.g. when temporarily
		283	replacing the coro thread description:
		284
		285	sub myfunction {
		286	local $Coro::current->{desc} = "inside myfunction(@_)";
		287
		288	# if we return or die here, the description will be restored
		289	}
		290
		291	=item 6. Viva La Zombie Muerte
		292
		293	Even after a thread has terminated and cleaned up its resources, the Coro
		294	object still is there and stores the return values of the thread.
		295
		296	The means the Coro object gets freed automatically when the thread has
		297	terminated and cleaned up and there arenot other references.
		298
		299	If there are, the Coro object will stay around, and you can call C<<
		300	->join >> as many times as you wish to retrieve the result values:
		301
		302	async {
		303	print "hi\n";
		304	1
		305	};
		306
		307	# run the async above, and free everything before returning
		308	# from Coro::cede:
		309	Coro::cede;
		310
		311	{
		312	my $coro = async {
		313	print "hi\n";
		314	1
		315	};
		316
		317	# run the async above, and clean up, but do not free the coro
		318	# object:
		319	Coro::cede;
		320
		321	# optionally retrieve the result values
		322	my @results = $coro->join;
		323
		324	# now $coro goes out of scope, and presumably gets freed
		325	};
		326
		327	=back
		328
68	=cut	329	=cut
69		330
70	package Coro;	331	package Coro;
71		332
72	use common::sense;	333	use common::sense;
…		…
81		342
82	our $idle; # idle handler	343	our $idle; # idle handler
83	our $main; # main coro	344	our $main; # main coro
84	our $current; # current coro	345	our $current; # current coro
85		346
86	our $VERSION = 5.21;	347	our $VERSION = 6.01;
87		348
88	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub rouse_cb rouse_wait);	349	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub rouse_cb rouse_wait);
89	our %EXPORT_TAGS = (	350	our %EXPORT_TAGS = (
90	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	351	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
91	);	352	);
…		…
131		392
132	The default implementation dies with "FATAL: deadlock detected.", followed	393	The default implementation dies with "FATAL: deadlock detected.", followed
133	by a thread listing, because the program has no other way to continue.	394	by a thread listing, because the program has no other way to continue.
134		395
135	This hook is overwritten by modules such as C<Coro::EV> and	396	This hook is overwritten by modules such as C<Coro::EV> and
136	C<Coro::AnyEvent> to wait on an external event that hopefully wake up a	397	C<Coro::AnyEvent> to wait on an external event that hopefully wakes up a
137	coro so the scheduler can run it.	398	coro so the scheduler can run it.
138		399
139	See L<Coro::EV> or L<Coro::AnyEvent> for examples of using this technique.	400	See L<Coro::EV> or L<Coro::AnyEvent> for examples of using this technique.
140		401
141	=cut	402	=cut
…		…
152	our @destroy;	413	our @destroy;
153	our $manager;	414	our $manager;
154		415
155	$manager = new Coro sub {	416	$manager = new Coro sub {
156	while () {	417	while () {
157	Coro::State::cancel shift @destroy	418	_destroy shift @destroy
158	while @destroy;	419	while @destroy;
159		420
160	&schedule;	421	&schedule;
161	}	422	}
162	};	423	};
…		…
296	coro, regardless of priority. This is useful sometimes to ensure	557	coro, regardless of priority. This is useful sometimes to ensure
297	progress is made.	558	progress is made.
298		559
299	=item terminate [arg...]	560	=item terminate [arg...]
300		561
301	Terminates the current coro with the given status values (see L<cancel>).	562	Terminates the current coro with the given status values (see
		563	L<cancel>). The values will not be copied, but referenced directly.
302		564
303	=item Coro::on_enter BLOCK, Coro::on_leave BLOCK	565	=item Coro::on_enter BLOCK, Coro::on_leave BLOCK
304		566
305	These function install enter and leave winders in the current scope. The	567	These function install enter and leave winders in the current scope. The
306	enter block will be executed when on_enter is called and whenever the	568	enter block will be executed when on_enter is called and whenever the
…		…
462	To avoid this, it is best to put a suspended coro into the ready queue	724	To avoid this, it is best to put a suspended coro into the ready queue
463	unconditionally, as every synchronisation mechanism must protect itself	725	unconditionally, as every synchronisation mechanism must protect itself
464	against spurious wakeups, and the one in the Coro family certainly do	726	against spurious wakeups, and the one in the Coro family certainly do
465	that.	727	that.
466		728
		729	=item $state->is_new
		730
		731	Returns true iff this Coro object is "new", i.e. has never been run
		732	yet. Those states basically consist of only the code reference to call and
		733	the arguments, but consumes very little other resources. New states will
		734	automatically get assigned a perl interpreter when they are transfered to.
		735
		736	=item $state->is_zombie
		737
		738	Returns true iff the Coro object has been cancelled, i.e.
		739	it's resources freed because they were C<cancel>'ed, C<terminate>'d,
		740	C<safe_cancel>'ed or simply went out of scope.
		741
		742	The name "zombie" stems from UNIX culture, where a process that has
		743	exited and only stores and exit status and no other resources is called a
		744	"zombie".
		745
467	=item $is_ready = $coro->is_ready	746	=item $is_ready = $coro->is_ready
468		747
469	Returns true iff the Coro object is in the ready queue. Unless the Coro	748	Returns true iff the Coro object is in the ready queue. Unless the Coro
470	object gets destroyed, it will eventually be scheduled by the scheduler.	749	object gets destroyed, it will eventually be scheduled by the scheduler.
471		750
…		…
480	Returns true iff this Coro object has been suspended. Suspended Coros will	759	Returns true iff this Coro object has been suspended. Suspended Coros will
481	not ever be scheduled.	760	not ever be scheduled.
482		761
483	=item $coro->cancel (arg...)	762	=item $coro->cancel (arg...)
484		763
485	Terminates the given Coro and makes it return the given arguments as	764	Terminates the given Coro thread and makes it return the given arguments as
486	status (default: the empty list). Never returns if the Coro is the	765	status (default: an empty list). Never returns if the Coro is the
487	current Coro.	766	current Coro.
488		767
489	=cut	768	This is a rather brutal way to free a coro, with some limitations - if
		769	the thread is inside a C callback that doesn't expect to be canceled,
		770	bad things can happen, or if the cancelled thread insists on running
		771	complicated cleanup handlers that rely on its thread context, things will
		772	not work.
490		773
491	sub cancel {	774	Any cleanup code being run (e.g. from C<guard> blocks) will be run without
492	my $self = shift;	775	a thread context, and is not allowed to switch to other threads. On the
		776	plus side, C<< ->cancel >> will always clean up the thread, no matter
		777	what. If your cleanup code is complex or you want to avoid cancelling a
		778	C-thread that doesn't know how to clean up itself, it can be better to C<<
		779	->throw >> an exception, or use C<< ->safe_cancel >>.
493		780
494	if ($current == $self) {	781	The arguments to C<< ->cancel >> are not copied, but instead will
495	terminate @_;	782	be referenced directly (e.g. if you pass C<$var> and after the call
496	} else {	783	change that variable, then you might change the return values passed to
497	$self->{_status} = [@_];	784	e.g. C<join>, so don't do that).
498	Coro::State::cancel $self;	785
		786	The resources of the Coro are usually freed (or destructed) before this
		787	call returns, but this can be delayed for an indefinite amount of time, as
		788	in some cases the manager thread has to run first to actually destruct the
		789	Coro object.
		790
		791	=item $coro->safe_cancel ($arg...)
		792
		793	Works mostly like C<< ->cancel >>, but is inherently "safer", and
		794	consequently, can fail with an exception in cases the thread is not in a
		795	cancellable state.
		796
		797	This method works a bit like throwing an exception that cannot be caught
		798	- specifically, it will clean up the thread from within itself, so
		799	all cleanup handlers (e.g. C<guard> blocks) are run with full thread
		800	context and can block if they wish. The downside is that there is no
		801	guarantee that the thread can be cancelled when you call this method, and
		802	therefore, it might fail. It is also considerably slower than C<cancel> or
		803	C<terminate>.
		804
		805	A thread is in a safe-cancellable state if it either hasn't been run yet,
		806	or it has no C context attached and is inside an SLF function.
		807
		808	The latter two basically mean that the thread isn't currently inside a
		809	perl callback called from some C function (usually via some XS modules)
		810	and isn't currently executing inside some C function itself (via Coro's XS
		811	API).
		812
		813	This call returns true when it could cancel the thread, or croaks with an
		814	error otherwise (i.e. it either returns true or doesn't return at all).
		815
		816	Why the weird interface? Well, there are two common models on how and
		817	when to cancel things. In the first, you have the expectation that your
		818	coro thread can be cancelled when you want to cancel it - if the thread
		819	isn't cancellable, this would be a bug somewhere, so C<< ->safe_cancel >>
		820	croaks to notify of the bug.
		821
		822	In the second model you sometimes want to ask nicely to cancel a thread,
		823	but if it's not a good time, well, then don't cancel. This can be done
		824	relatively easy like this:
		825
		826	if (! eval { $coro->safe_cancel }) {
		827	warn "unable to cancel thread: $@";
499	}	828	}
500	}	829
		830	However, what you never should do is first try to cancel "safely" and
		831	if that fails, cancel the "hard" way with C<< ->cancel >>. That makes
		832	no sense: either you rely on being able to execute cleanup code in your
		833	thread context, or you don't. If you do, then C<< ->safe_cancel >> is the
		834	only way, and if you don't, then C<< ->cancel >> is always faster and more
		835	direct.
501		836
502	=item $coro->schedule_to	837	=item $coro->schedule_to
503		838
504	Puts the current coro to sleep (like C<Coro::schedule>), but instead	839	Puts the current coro to sleep (like C<Coro::schedule>), but instead
505	of continuing with the next coro from the ready queue, always switch to	840	of continuing with the next coro from the ready queue, always switch to
…		…
524	inside the coro at the next convenient point in time. Otherwise	859	inside the coro at the next convenient point in time. Otherwise
525	clears the exception object.	860	clears the exception object.
526		861
527	Coro will check for the exception each time a schedule-like-function	862	Coro will check for the exception each time a schedule-like-function
528	returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down	863	returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down
529	>>, C<< Coro::Handle->readable >> and so on. Most of these functions	864	>>, C<< Coro::Handle->readable >> and so on. Most of those functions (all
530	detect this case and return early in case an exception is pending.	865	that are part of Coro itself) detect this case and return early in case an
		866	exception is pending.
531		867
532	The exception object will be thrown "as is" with the specified scalar in	868	The exception object will be thrown "as is" with the specified scalar in
533	C<$@>, i.e. if it is a string, no line number or newline will be appended	869	C<$@>, i.e. if it is a string, no line number or newline will be appended
534	(unlike with C<die>).	870	(unlike with C<die>).
535		871
536	This can be used as a softer means than C<cancel> to ask a coro to	872	This can be used as a softer means than either C<cancel> or C<safe_cancel
537	end itself, although there is no guarantee that the exception will lead to	873	>to ask a coro to end itself, although there is no guarantee that the
538	termination, and if the exception isn't caught it might well end the whole	874	exception will lead to termination, and if the exception isn't caught it
539	program.	875	might well end the whole program.
540		876
541	You might also think of C<throw> as being the moral equivalent of	877	You might also think of C<throw> as being the moral equivalent of
542	C<kill>ing a coro with a signal (in this case, a scalar).	878	C<kill>ing a coro with a signal (in this case, a scalar).
543		879
544	=item $coro->join	880	=item $coro->join
545		881
546	Wait until the coro terminates and return any values given to the	882	Wait until the coro terminates and return any values given to the
547	C<terminate> or C<cancel> functions. C<join> can be called concurrently	883	C<terminate> or C<cancel> functions. C<join> can be called concurrently
548	from multiple coro, and all will be resumed and given the status	884	from multiple threads, and all will be resumed and given the status
549	return once the C<$coro> terminates.	885	return once the C<$coro> terminates.
550		886
551	=cut
552
553	sub join {
554	my $self = shift;
555
556	unless ($self->{_status}) {
557	my $current = $current;
558
559	push @{$self->{_on_destroy}}, sub {
560	$current->ready;
561	undef $current;
562	};
563
564	&schedule while $current;
565	}
566
567	wantarray ? @{$self->{_status}} : $self->{_status}[0];
568	}
569
570	=item $coro->on_destroy (\&cb)	887	=item $coro->on_destroy (\&cb)
571		888
572	Registers a callback that is called when this coro gets destroyed,	889	Registers a callback that is called when this coro thread gets destroyed,
573	but before it is joined. The callback gets passed the terminate arguments,	890	that is, after it's resources have been freed but before it is joined. The
		891	callback gets passed the terminate/cancel arguments, if any, and I<must
574	if any, and I<must not> die, under any circumstances.	892	not> die, under any circumstances.
575		893
576	=cut	894	There can be any number of C<on_destroy> callbacks per coro, and there is
577		895	no way currently to remove a callback once added.
578	sub on_destroy {
579	my ($self, $cb) = @_;
580
581	push @{ $self->{_on_destroy} }, $cb;
582	}
583		896
584	=item $oldprio = $coro->prio ($newprio)	897	=item $oldprio = $coro->prio ($newprio)
585		898
586	Sets (or gets, if the argument is missing) the priority of the	899	Sets (or gets, if the argument is missing) the priority of the
587	coro. Higher priority coro get run before lower priority	900	coro thread. Higher priority coro get run before lower priority
588	coro. Priorities are small signed integers (currently -4 .. +3),	901	coros. Priorities are small signed integers (currently -4 .. +3),
589	that you can refer to using PRIO_xxx constants (use the import tag :prio	902	that you can refer to using PRIO_xxx constants (use the import tag :prio
590	to get then):	903	to get then):
591		904
592	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN	905	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
593	3 > 1 > 0 > -1 > -3 > -4	906	3 > 1 > 0 > -1 > -3 > -4
594		907
595	# set priority to HIGH	908	# set priority to HIGH
596	current->prio (PRIO_HIGH);	909	current->prio (PRIO_HIGH);
597		910
598	The idle coro ($Coro::idle) always has a lower priority than any	911	The idle coro thread ($Coro::idle) always has a lower priority than any
599	existing coro.	912	existing coro.
600		913
601	Changing the priority of the current coro will take effect immediately,	914	Changing the priority of the current coro will take effect immediately,
602	but changing the priority of coro in the ready queue (but not	915	but changing the priority of a coro in the ready queue (but not running)
603	running) will only take effect after the next schedule (of that	916	will only take effect after the next schedule (of that coro). This is a
604	coro). This is a bug that will be fixed in some future version.	917	bug that will be fixed in some future version.
605		918
606	=item $newprio = $coro->nice ($change)	919	=item $newprio = $coro->nice ($change)
607		920
608	Similar to C<prio>, but subtract the given value from the priority (i.e.	921	Similar to C<prio>, but subtract the given value from the priority (i.e.
609	higher values mean lower priority, just as in unix).	922	higher values mean lower priority, just as in UNIX's nice command).
610		923
611	=item $olddesc = $coro->desc ($newdesc)	924	=item $olddesc = $coro->desc ($newdesc)
612		925
613	Sets (or gets in case the argument is missing) the description for this	926	Sets (or gets in case the argument is missing) the description for this
614	coro. This is just a free-form string you can associate with a	927	coro thread. This is just a free-form string you can associate with a
615	coro.	928	coro.
616		929
617	This method simply sets the C<< $coro->{desc} >> member to the given	930	This method simply sets the C<< $coro->{desc} >> member to the given
618	string. You can modify this member directly if you wish.	931	string. You can modify this member directly if you wish, and in fact, this
		932	is often preferred to indicate major processing states that cna then be
		933	seen for example in a L<Coro::Debug> session:
		934
		935	sub my_long_function {
		936	local $Coro::current->{desc} = "now in my_long_function";
		937	...
		938	$Coro::current->{desc} = "my_long_function: phase 1";
		939	...
		940	$Coro::current->{desc} = "my_long_function: phase 2";
		941	...
		942	}
619		943
620	=cut	944	=cut
621		945
622	sub desc {	946	sub desc {
623	my $old = $_[0]{desc};	947	my $old = $_[0]{desc};
…		…
660	returning a new coderef. Unblocking means that calling the new coderef	984	returning a new coderef. Unblocking means that calling the new coderef
661	will return immediately without blocking, returning nothing, while the	985	will return immediately without blocking, returning nothing, while the
662	original code ref will be called (with parameters) from within another	986	original code ref will be called (with parameters) from within another
663	coro.	987	coro.
664		988
665	The reason this function exists is that many event libraries (such as the	989	The reason this function exists is that many event libraries (such as
666	venerable L<Event\|Event> module) are not thread-safe (a weaker form	990	the venerable L<Event\|Event> module) are not thread-safe (a weaker form
667	of reentrancy). This means you must not block within event callbacks,	991	of reentrancy). This means you must not block within event callbacks,
668	otherwise you might suffer from crashes or worse. The only event library	992	otherwise you might suffer from crashes or worse. The only event library
669	currently known that is safe to use without C<unblock_sub> is L<EV>.	993	currently known that is safe to use without C<unblock_sub> is L<EV> (but
		994	you might still run into deadlocks if all event loops are blocked).
670		995
671	Coro will try to catch you when you block in the event loop	996	Coro will try to catch you when you block in the event loop
672	("FATAL:$Coro::IDLE blocked itself"), but this is just best effort and	997	("FATAL:$Coro::IDLE blocked itself"), but this is just best effort and
673	only works when you do not run your own event loop.	998	only works when you do not run your own event loop.
674		999
…		…
745		1070
746	=back	1071	=back
747		1072
748	=cut	1073	=cut
749		1074
		1075	for my $module (qw(Channel RWLock Semaphore SemaphoreSet Signal Specific)) {
		1076	my $old = defined &{"Coro::$module\::new"} && \&{"Coro::$module\::new"};
		1077
		1078	*{"Coro::$module\::new"} = sub {
		1079	require "Coro/$module.pm";
		1080
		1081	# some modules have their new predefined in State.xs, some don't
		1082	*{"Coro::$module\::new"} = $old
		1083	if $old;
		1084
		1085	goto &{"Coro::$module\::new"};
		1086	};
		1087	}
		1088
750	1;	1089	1;
751		1090
752	=head1 HOW TO WAIT FOR A CALLBACK	1091	=head1 HOW TO WAIT FOR A CALLBACK
753		1092
754	It is very common for a coro to wait for some callback to be	1093	It is very common for a coro to wait for some callback to be
…		…
833	future to allow per-thread schedulers, but Coro::State does not yet allow	1172	future to allow per-thread schedulers, but Coro::State does not yet allow
834	this). I recommend disabling thread support and using processes, as having	1173	this). I recommend disabling thread support and using processes, as having
835	the windows process emulation enabled under unix roughly halves perl	1174	the windows process emulation enabled under unix roughly halves perl
836	performance, even when not used.	1175	performance, even when not used.
837		1176
		1177	Attempts to use threads created in another emulated process will crash
		1178	("cleanly", with a null pointer exception).
		1179
838	=item coro switching is not signal safe	1180	=item coro switching is not signal safe
839		1181
840	You must not switch to another coro from within a signal handler (only	1182	You must not switch to another coro from within a signal handler (only
841	relevant with %SIG - most event libraries provide safe signals), I<unless>	1183	relevant with %SIG - most event libraries provide safe signals), I<unless>
842	you are sure you are not interrupting a Coro function.	1184	you are sure you are not interrupting a Coro function.
…		…
857	ithreads (for example, that memory or files would be shared), showing his	1199	ithreads (for example, that memory or files would be shared), showing his
858	lack of understanding of this area - if it is hard to understand for Chip,	1200	lack of understanding of this area - if it is hard to understand for Chip,
859	it is probably not obvious to everybody).	1201	it is probably not obvious to everybody).
860		1202
861	What follows is an ultra-condensed version of my talk about threads in	1203	What follows is an ultra-condensed version of my talk about threads in
862	scripting languages given onthe perl workshop 2009:	1204	scripting languages given on the perl workshop 2009:
863		1205
864	The so-called "ithreads" were originally implemented for two reasons:	1206	The so-called "ithreads" were originally implemented for two reasons:
865	first, to (badly) emulate unix processes on native win32 perls, and	1207	first, to (badly) emulate unix processes on native win32 perls, and
866	secondly, to replace the older, real thread model ("5.005-threads").	1208	secondly, to replace the older, real thread model ("5.005-threads").
867		1209

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Comparing Coro/Coro.pm (file contents): Revision 1.275 by root, Wed Mar 31 17:41:07 2010 UTC vs. Revision 1.301 by root, Sun Jul 3 10:51:40 2011 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.275 by root, Wed Mar 31 17:41:07 2010 UTC vs.
Revision 1.301 by root, Sun Jul 3 10:51:40 2011 UTC