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

Comparing Coro/Coro.pm (file contents):
Revision 1.282 by root, Sun Dec 26 16:23:51 2010 UTC vs.
Revision 1.358 by root, Wed Jul 21 06:37:08 2021 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 its 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 its 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 >>, the
		194	thread-equivalent of C<exit>, which works at any subroutine call nesting
		195	level:
		196
		197	async {
		198	Coro::terminate "return value 1", "return value 2";
		199	};
		200
		201	Yet another way is to C<< ->cancel >> (or C<< ->safe_cancel >>) the coro
		202	thread from another thread:
		203
		204	my $coro = async {
		205	exit 1;
		206	};
		207
		208	$coro->cancel; # also accepts values for ->join to retrieve
		209
		210	Cancellation I<can> be dangerous - it's a bit like calling C<exit> without
		211	actually exiting, and might leave C libraries and XS modules in a weird
		212	state. Unlike other thread implementations, however, Coro is exceptionally
		213	safe with regards to cancellation, as perl will always be in a consistent
		214	state, and for those cases where you want to do truly marvellous things
		215	with your coro while it is being cancelled - that is, make sure all
		216	cleanup code is executed from the thread being cancelled - there is even a
		217	C<< ->safe_cancel >> method.
		218
		219	So, cancelling a thread that runs in an XS event loop might not be the
		220	best idea, but any other combination that deals with perl only (cancelling
		221	when a thread is in a C<tie> method or an C<AUTOLOAD> for example) is
		222	safe.
		223
		224	Last not least, a coro thread object that isn't referenced is C<<
		225	->cancel >>'ed automatically - just like other objects in Perl. This
		226	is not such a common case, however - a running thread is referencedy by
		227	C<$Coro::current>, a thread ready to run is referenced by the ready queue,
		228	a thread waiting on a lock or semaphore is referenced by being in some
		229	wait list and so on. But a thread that isn't in any of those queues gets
		230	cancelled:
		231
		232	async {
		233	schedule; # cede to other coros, don't go into the ready queue
		234	};
		235
		236	cede;
		237	# now the async above is destroyed, as it is not referenced by anything.
		238
		239	A slightly embellished example might make it clearer:
		240
		241	async {
		242	my $guard = Guard::guard { print "destroyed\n" };
		243	schedule while 1;
		244	};
		245
		246	cede;
		247
		248	Superficially one might not expect any output - since the C<async>
		249	implements an endless loop, the C<$guard> will not be cleaned up. However,
		250	since the thread object returned by C<async> is not stored anywhere, the
		251	thread is initially referenced because it is in the ready queue, when it
		252	runs it is referenced by C<$Coro::current>, but when it calls C<schedule>,
		253	it gets C<cancel>ed causing the guard object to be destroyed (see the next
		254	section), and printing its message.
		255
		256	If this seems a bit drastic, remember that this only happens when nothing
		257	references the thread anymore, which means there is no way to further
		258	execute it, ever. The only options at this point are leaking the thread,
		259	or cleaning it up, which brings us to...
		260
		261	=item 5. Cleanup
		262
		263	Threads will allocate various resources. Most but not all will be returned
		264	when a thread terminates, during clean-up.
		265
		266	Cleanup is quite similar to throwing an uncaught exception: perl will
		267	work its way up through all subroutine calls and blocks. On its way, it
		268	will release all C<my> variables, undo all C<local>'s and free any other
		269	resources truly local to the thread.
		270
		271	So, a common way to free resources is to keep them referenced only by my
		272	variables:
		273
		274	async {
		275	my $big_cache = new Cache ...;
		276	};
		277
		278	If there are no other references, then the C<$big_cache> object will be
		279	freed when the thread terminates, regardless of how it does so.
		280
		281	What it does C<NOT> do is unlock any Coro::Semaphores or similar
		282	resources, but that's where the C<guard> methods come in handy:
		283
		284	my $sem = new Coro::Semaphore;
		285
		286	async {
		287	my $lock_guard = $sem->guard;
		288	# if we return, or die or get cancelled, here,
		289	# then the semaphore will be "up"ed.
		290	};
		291
		292	The C<Guard::guard> function comes in handy for any custom cleanup you
		293	might want to do (but you cannot switch to other coroutines from those
		294	code blocks):
		295
		296	async {
		297	my $window = new Gtk2::Window "toplevel";
		298	# The window will not be cleaned up automatically, even when $window
		299	# gets freed, so use a guard to ensure its destruction
		300	# in case of an error:
		301	my $window_guard = Guard::guard { $window->destroy };
		302
		303	# we are safe here
		304	};
		305
		306	Last not least, C<local> can often be handy, too, e.g. when temporarily
		307	replacing the coro thread description:
		308
		309	sub myfunction {
		310	local $Coro::current->{desc} = "inside myfunction(@_)";
		311
		312	# if we return or die here, the description will be restored
		313	}
		314
		315	=item 6. Viva La Zombie Muerte
		316
		317	Even after a thread has terminated and cleaned up its resources, the Coro
		318	object still is there and stores the return values of the thread.
		319
		320	When there are no other references, it will simply be cleaned up and
		321	freed.
		322
		323	If there areany references, the Coro object will stay around, and you
		324	can call C<< ->join >> as many times as you wish to retrieve the result
		325	values:
		326
		327	async {
		328	print "hi\n";
		329	1
		330	};
		331
		332	# run the async above, and free everything before returning
		333	# from Coro::cede:
		334	Coro::cede;
		335
		336	{
		337	my $coro = async {
		338	print "hi\n";
		339	1
		340	};
		341
		342	# run the async above, and clean up, but do not free the coro
		343	# object:
		344	Coro::cede;
		345
		346	# optionally retrieve the result values
		347	my @results = $coro->join;
		348
		349	# now $coro goes out of scope, and presumably gets freed
		350	};
		351
		352	=back
		353
68	=cut	354	=cut
69		355
70	package Coro;	356	package Coro;
71		357
72	use common::sense;	358	use common::sense;
…		…
81		367
82	our $idle; # idle handler	368	our $idle; # idle handler
83	our $main; # main coro	369	our $main; # main coro
84	our $current; # current coro	370	our $current; # current coro
85		371
86	our $VERSION = 5.25;	372	our $VERSION = 6.57;
87		373
88	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub rouse_cb rouse_wait);	374	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub rouse_cb rouse_wait);
89	our %EXPORT_TAGS = (	375	our %EXPORT_TAGS = (
90	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	376	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
91	);	377	);
…		…
96	=over 4	382	=over 4
97		383
98	=item $Coro::main	384	=item $Coro::main
99		385
100	This variable stores the Coro object that represents the main	386	This variable stores the Coro object that represents the main
101	program. While you cna C<ready> it and do most other things you can do to	387	program. While you can C<ready> it and do most other things you can do to
102	coro, it is mainly useful to compare again C<$Coro::current>, to see	388	coro, it is mainly useful to compare again C<$Coro::current>, to see
103	whether you are running in the main program or not.	389	whether you are running in the main program or not.
104		390
105	=cut	391	=cut
106		392
…		…
131		417
132	The default implementation dies with "FATAL: deadlock detected.", followed	418	The default implementation dies with "FATAL: deadlock detected.", followed
133	by a thread listing, because the program has no other way to continue.	419	by a thread listing, because the program has no other way to continue.
134		420
135	This hook is overwritten by modules such as C<Coro::EV> and	421	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	422	C<Coro::AnyEvent> to wait on an external event that hopefully wakes up a
137	coro so the scheduler can run it.	423	coro so the scheduler can run it.
138		424
139	See L<Coro::EV> or L<Coro::AnyEvent> for examples of using this technique.	425	See L<Coro::EV> or L<Coro::AnyEvent> for examples of using this technique.
140		426
141	=cut	427	=cut
…		…
152	our @destroy;	438	our @destroy;
153	our $manager;	439	our $manager;
154		440
155	$manager = new Coro sub {	441	$manager = new Coro sub {
156	while () {	442	while () {
157	Coro::State::cancel shift @destroy	443	_destroy shift @destroy
158	while @destroy;	444	while @destroy;
159		445
160	&schedule;	446	&schedule;
161	}	447	}
162	};	448	};
…		…
213	C<async> does. As the coro is being reused, stuff like C<on_destroy>	499	C<async> does. As the coro is being reused, stuff like C<on_destroy>
214	will not work in the expected way, unless you call terminate or cancel,	500	will not work in the expected way, unless you call terminate or cancel,
215	which somehow defeats the purpose of pooling (but is fine in the	501	which somehow defeats the purpose of pooling (but is fine in the
216	exceptional case).	502	exceptional case).
217		503
218	The priority will be reset to C<0> after each run, tracing will be	504	The priority will be reset to C<0> after each run, all C<swap_sv> calls
219	disabled, the description will be reset and the default output filehandle	505	will be undone, tracing will be disabled, the description will be reset
220	gets restored, so you can change all these. Otherwise the coro will	506	and the default output filehandle gets restored, so you can change all
221	be re-used "as-is": most notably if you change other per-coro global	507	these. Otherwise the coro will be re-used "as-is": most notably if you
222	stuff such as C<$/> you I<must needs> revert that change, which is most	508	change other per-coro global stuff such as C<$/> you I<must needs> revert
223	simply done by using local as in: C<< local $/ >>.	509	that change, which is most simply done by using local as in: C<< local $/
		510	>>.
224		511
225	The idle pool size is limited to C<8> idle coros (this can be	512	The idle pool size is limited to C<8> idle coros (this can be
226	adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle	513	adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle
227	coros as required.	514	coros as required.
228		515
…		…
296	coro, regardless of priority. This is useful sometimes to ensure	583	coro, regardless of priority. This is useful sometimes to ensure
297	progress is made.	584	progress is made.
298		585
299	=item terminate [arg...]	586	=item terminate [arg...]
300		587
301	Terminates the current coro with the given status values (see L<cancel>).	588	Terminates the current coro with the given status values (see
		589	L<cancel>). The values will not be copied, but referenced directly.
302		590
303	=item Coro::on_enter BLOCK, Coro::on_leave BLOCK	591	=item Coro::on_enter BLOCK, Coro::on_leave BLOCK
304		592
305	These function install enter and leave winders in the current scope. The	593	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	594	enter block will be executed when on_enter is called and whenever the
…		…
351	# at this place, the timezone is Antarctica/South_Pole,	639	# at this place, the timezone is Antarctica/South_Pole,
352	# without disturbing the TZ of any other coro.	640	# without disturbing the TZ of any other coro.
353	};	641	};
354		642
355	This can be used to localise about any resource (locale, uid, current	643	This can be used to localise about any resource (locale, uid, current
356	working directory etc.) to a block, despite the existance of other	644	working directory etc.) to a block, despite the existence of other
357	coros.	645	coros.
358		646
359	Another interesting example implements time-sliced multitasking using	647	Another interesting example implements time-sliced multitasking using
360	interval timers (this could obviously be optimised, but does the job):	648	interval timers (this could obviously be optimised, but does the job):
361		649
…		…
366	Coro::on_enter {	654	Coro::on_enter {
367	# on entering the thread, we set an VTALRM handler to cede	655	# on entering the thread, we set an VTALRM handler to cede
368	$SIG{VTALRM} = sub { cede };	656	$SIG{VTALRM} = sub { cede };
369	# and then start the interval timer	657	# and then start the interval timer
370	Time::HiRes::setitimer &Time::HiRes::ITIMER_VIRTUAL, 0.01, 0.01;	658	Time::HiRes::setitimer &Time::HiRes::ITIMER_VIRTUAL, 0.01, 0.01;
371	};	659	};
372	Coro::on_leave {	660	Coro::on_leave {
373	# on leaving the thread, we stop the interval timer again	661	# on leaving the thread, we stop the interval timer again
374	Time::HiRes::setitimer &Time::HiRes::ITIMER_VIRTUAL, 0, 0;	662	Time::HiRes::setitimer &Time::HiRes::ITIMER_VIRTUAL, 0, 0;
375	};	663	};
376		664
377	&{+shift};	665	&{+shift};
378	}	666	}
379		667
380	# use like this:	668	# use like this:
381	timeslice {	669	timeslice {
382	# The following is an endless loop that would normally	670	# The following is an endless loop that would normally
383	# monopolise the process. Since it runs in a timesliced	671	# monopolise the process. Since it runs in a timesliced
384	# environment, it will regularly cede to other threads.	672	# environment, it will regularly cede to other threads.
385	while () { }	673	while () { }
386	};	674	};
387		675
388		676
389	=item killall	677	=item killall
390		678
391	Kills/terminates/cancels all coros except the currently running one.	679	Kills/terminates/cancels all coros except the currently running one.
…		…
462	To avoid this, it is best to put a suspended coro into the ready queue	750	To avoid this, it is best to put a suspended coro into the ready queue
463	unconditionally, as every synchronisation mechanism must protect itself	751	unconditionally, as every synchronisation mechanism must protect itself
464	against spurious wakeups, and the one in the Coro family certainly do	752	against spurious wakeups, and the one in the Coro family certainly do
465	that.	753	that.
466		754
		755	=item $state->is_new
		756
		757	Returns true iff this Coro object is "new", i.e. has never been run
		758	yet. Those states basically consist of only the code reference to call and
		759	the arguments, but consumes very little other resources. New states will
		760	automatically get assigned a perl interpreter when they are transferred to.
		761
		762	=item $state->is_zombie
		763
		764	Returns true iff the Coro object has been cancelled, i.e.
		765	its resources freed because they were C<cancel>'ed, C<terminate>'d,
		766	C<safe_cancel>'ed or simply went out of scope.
		767
		768	The name "zombie" stems from UNIX culture, where a process that has
		769	exited and only stores and exit status and no other resources is called a
		770	"zombie".
		771
467	=item $is_ready = $coro->is_ready	772	=item $is_ready = $coro->is_ready
468		773
469	Returns true iff the Coro object is in the ready queue. Unless the Coro	774	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.	775	object gets destroyed, it will eventually be scheduled by the scheduler.
471		776
…		…
478	=item $is_suspended = $coro->is_suspended	783	=item $is_suspended = $coro->is_suspended
479		784
480	Returns true iff this Coro object has been suspended. Suspended Coros will	785	Returns true iff this Coro object has been suspended. Suspended Coros will
481	not ever be scheduled.	786	not ever be scheduled.
482		787
483	=item $coro->cancel (arg...)	788	=item $coro->cancel ($arg...)
484		789
485	Terminates the given Coro and makes it return the given arguments as	790	Terminate the given Coro thread and make it return the given arguments as
486	status (default: the empty list). Never returns if the Coro is the	791	status (default: an empty list). Never returns if the Coro is the
487	current Coro.	792	current Coro.
488		793
489	=cut	794	This is a rather brutal way to free a coro, with some limitations - if
		795	the thread is inside a C callback that doesn't expect to be canceled,
		796	bad things can happen, or if the cancelled thread insists on running
		797	complicated cleanup handlers that rely on its thread context, things will
		798	not work.
490		799
491	sub cancel {	800	Any cleanup code being run (e.g. from C<guard> blocks, destructors and so
492	my $self = shift;	801	on) will be run without a thread context, and is not allowed to switch
		802	to other threads. A common mistake is to call C<< ->cancel >> from a
		803	destructor called by die'ing inside the thread to be cancelled for
		804	example.
493		805
494	if ($current == $self) {	806	On the plus side, C<< ->cancel >> will always clean up the thread, no
495	terminate @_;	807	matter what. If your cleanup code is complex or you want to avoid
496	} else {	808	cancelling a C-thread that doesn't know how to clean up itself, it can be
497	$self->{_status} = [@_];	809	better to C<< ->throw >> an exception, or use C<< ->safe_cancel >>.
498	Coro::State::cancel $self;	810
		811	The arguments to C<< ->cancel >> are not copied, but instead will
		812	be referenced directly (e.g. if you pass C<$var> and after the call
		813	change that variable, then you might change the return values passed to
		814	e.g. C<join>, so don't do that).
		815
		816	The resources of the Coro are usually freed (or destructed) before this
		817	call returns, but this can be delayed for an indefinite amount of time, as
		818	in some cases the manager thread has to run first to actually destruct the
		819	Coro object.
		820
		821	=item $coro->safe_cancel ($arg...)
		822
		823	Works mostly like C<< ->cancel >>, but is inherently "safer", and
		824	consequently, can fail with an exception in cases the thread is not in a
		825	cancellable state. Essentially, C<< ->safe_cancel >> is a C<< ->cancel >>
		826	with extra checks before canceling.
		827
		828	It works a bit like throwing an exception that cannot be caught -
		829	specifically, it will clean up the thread from within itself, so all
		830	cleanup handlers (e.g. C<guard> blocks) are run with full thread
		831	context and can block if they wish. The downside is that there is no
		832	guarantee that the thread can be cancelled when you call this method, and
		833	therefore, it might fail. It is also considerably slower than C<cancel> or
		834	C<terminate>.
		835
		836	A thread is in a safe-cancellable state if it either has never been run
		837	yet, has already been canceled/terminated or otherwise destroyed, or has
		838	no C context attached and is inside an SLF function.
		839
		840	The first two states are trivial - a thread that hasnot started or has
		841	already finished is safe to cancel.
		842
		843	The last state basically means that the thread isn't currently inside a
		844	perl callback called from some C function (usually via some XS modules)
		845	and isn't currently executing inside some C function itself (via Coro's XS
		846	API).
		847
		848	This call returns true when it could cancel the thread, or croaks with an
		849	error otherwise (i.e. it either returns true or doesn't return at all).
		850
		851	Why the weird interface? Well, there are two common models on how and
		852	when to cancel things. In the first, you have the expectation that your
		853	coro thread can be cancelled when you want to cancel it - if the thread
		854	isn't cancellable, this would be a bug somewhere, so C<< ->safe_cancel >>
		855	croaks to notify of the bug.
		856
		857	In the second model you sometimes want to ask nicely to cancel a thread,
		858	but if it's not a good time, well, then don't cancel. This can be done
		859	relatively easy like this:
		860
		861	if (! eval { $coro->safe_cancel }) {
		862	warn "unable to cancel thread: $@";
499	}	863	}
500	}	864
		865	However, what you never should do is first try to cancel "safely" and
		866	if that fails, cancel the "hard" way with C<< ->cancel >>. That makes
		867	no sense: either you rely on being able to execute cleanup code in your
		868	thread context, or you don't. If you do, then C<< ->safe_cancel >> is the
		869	only way, and if you don't, then C<< ->cancel >> is always faster and more
		870	direct.
501		871
502	=item $coro->schedule_to	872	=item $coro->schedule_to
503		873
504	Puts the current coro to sleep (like C<Coro::schedule>), but instead	874	Puts the current coro to sleep (like C<Coro::schedule>), but instead
505	of continuing with the next coro from the ready queue, always switch to	875	of continuing with the next coro from the ready queue, always switch to
…		…
524	inside the coro at the next convenient point in time. Otherwise	894	inside the coro at the next convenient point in time. Otherwise
525	clears the exception object.	895	clears the exception object.
526		896
527	Coro will check for the exception each time a schedule-like-function	897	Coro will check for the exception each time a schedule-like-function
528	returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down	898	returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down
529	>>, C<< Coro::Handle->readable >> and so on. Most of these functions	899	>>, C<< Coro::Handle->readable >> and so on. Most of those functions (all
530	detect this case and return early in case an exception is pending.	900	that are part of Coro itself) detect this case and return early in case an
		901	exception is pending.
531		902
532	The exception object will be thrown "as is" with the specified scalar in	903	The exception object will be thrown "as is" with the specified scalar in
533	C<$@>, i.e. if it is a string, no line number or newline will be appended	904	C<$@>, i.e. if it is a string, no line number or newline will be appended
534	(unlike with C<die>).	905	(unlike with C<die>).
535		906
536	This can be used as a softer means than C<cancel> to ask a coro to	907	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	908	>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	909	exception will lead to termination, and if the exception isn't caught it
539	program.	910	might well end the whole program.
540		911
541	You might also think of C<throw> as being the moral equivalent of	912	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).	913	C<kill>ing a coro with a signal (in this case, a scalar).
543		914
544	=item $coro->join	915	=item $coro->join
545		916
546	Wait until the coro terminates and return any values given to the	917	Wait until the coro terminates and return any values given to the
547	C<terminate> or C<cancel> functions. C<join> can be called concurrently	918	C<terminate> or C<cancel> functions. C<join> can be called concurrently
548	from multiple coro, and all will be resumed and given the status	919	from multiple threads, and all will be resumed and given the status
549	return once the C<$coro> terminates.	920	return once the C<$coro> terminates.
550		921
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)	922	=item $coro->on_destroy (\&cb)
571		923
572	Registers a callback that is called when this coro gets destroyed,	924	Registers a callback that is called when this coro thread gets destroyed,
573	but before it is joined. The callback gets passed the terminate arguments,	925	that is, after its resources have been freed but before it is joined. The
		926	callback gets passed the terminate/cancel arguments, if any, and I<must
574	if any, and I<must not> die, under any circumstances.	927	not> die, under any circumstances.
575		928
576	=cut	929	There can be any number of C<on_destroy> callbacks per coro, and there is
577		930	currently no way to remove a callback once added.
578	sub on_destroy {
579	my ($self, $cb) = @_;
580
581	push @{ $self->{_on_destroy} }, $cb;
582	}
583		931
584	=item $oldprio = $coro->prio ($newprio)	932	=item $oldprio = $coro->prio ($newprio)
585		933
586	Sets (or gets, if the argument is missing) the priority of the	934	Sets (or gets, if the argument is missing) the priority of the
587	coro. Higher priority coro get run before lower priority	935	coro thread. Higher priority coro get run before lower priority
588	coro. Priorities are small signed integers (currently -4 .. +3),	936	coros. Priorities are small signed integers (currently -4 .. +3),
589	that you can refer to using PRIO_xxx constants (use the import tag :prio	937	that you can refer to using PRIO_xxx constants (use the import tag :prio
590	to get then):	938	to get then):
591		939
592	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN	940	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
593	3 > 1 > 0 > -1 > -3 > -4	941	3 > 1 > 0 > -1 > -3 > -4
594		942
595	# set priority to HIGH	943	# set priority to HIGH
596	current->prio (PRIO_HIGH);	944	current->prio (PRIO_HIGH);
597		945
598	The idle coro ($Coro::idle) always has a lower priority than any	946	The idle coro thread ($Coro::idle) always has a lower priority than any
599	existing coro.	947	existing coro.
600		948
601	Changing the priority of the current coro will take effect immediately,	949	Changing the priority of the current coro will take effect immediately,
602	but changing the priority of coro in the ready queue (but not	950	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	951	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.	952	bug that will be fixed in some future version.
605		953
606	=item $newprio = $coro->nice ($change)	954	=item $newprio = $coro->nice ($change)
607		955
608	Similar to C<prio>, but subtract the given value from the priority (i.e.	956	Similar to C<prio>, but subtract the given value from the priority (i.e.
609	higher values mean lower priority, just as in unix).	957	higher values mean lower priority, just as in UNIX's nice command).
610		958
611	=item $olddesc = $coro->desc ($newdesc)	959	=item $olddesc = $coro->desc ($newdesc)
612		960
613	Sets (or gets in case the argument is missing) the description for this	961	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	962	coro thread. This is just a free-form string you can associate with a
615	coro.	963	coro.
616		964
617	This method simply sets the C<< $coro->{desc} >> member to the given	965	This method simply sets the C<< $coro->{desc} >> member to the given
618	string. You can modify this member directly if you wish, and in fact, this	966	string. You can modify this member directly if you wish, and in fact, this
619	is often preferred to indicate major processing states that cna then be	967	is often preferred to indicate major processing states that can then be
620	seen for example in a L<Coro::Debug> session:	968	seen for example in a L<Coro::Debug> session:
621		969
622	sub my_long_function {	970	sub my_long_function {
623	local $Coro::current->{desc} = "now in my_long_function";	971	local $Coro::current->{desc} = "now in my_long_function";
624	...	972	...
…		…
679	otherwise you might suffer from crashes or worse. The only event library	1027	otherwise you might suffer from crashes or worse. The only event library
680	currently known that is safe to use without C<unblock_sub> is L<EV> (but	1028	currently known that is safe to use without C<unblock_sub> is L<EV> (but
681	you might still run into deadlocks if all event loops are blocked).	1029	you might still run into deadlocks if all event loops are blocked).
682		1030
683	Coro will try to catch you when you block in the event loop	1031	Coro will try to catch you when you block in the event loop
684	("FATAL:$Coro::IDLE blocked itself"), but this is just best effort and	1032	("FATAL: $Coro::idle blocked itself"), but this is just best effort and
685	only works when you do not run your own event loop.	1033	only works when you do not run your own event loop.
686		1034
687	This function allows your callbacks to block by executing them in another	1035	This function allows your callbacks to block by executing them in another
688	coro where it is safe to block. One example where blocking is handy	1036	coro where it is safe to block. One example where blocking is handy
689	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to	1037	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
…		…
738		1086
739	Create and return a "rouse callback". That's a code reference that,	1087	Create and return a "rouse callback". That's a code reference that,
740	when called, will remember a copy of its arguments and notify the owner	1088	when called, will remember a copy of its arguments and notify the owner
741	coro of the callback.	1089	coro of the callback.
742		1090
		1091	Only the first invocation will store agruments and signal any waiter -
		1092	further calls will effectively be ignored, but it is ok to try.
		1093
743	See the next function.	1094	Also see the next function.
744		1095
745	=item @args = rouse_wait [$cb]	1096	=item @args = rouse_wait [$cb]
746		1097
747	Wait for the specified rouse callback (or the last one that was created in	1098	Wait for the specified rouse callback to be invoked (or if the argument is
748	this coro).	1099	missing, use the most recently created callback in the current coro).
749		1100
750	As soon as the callback is invoked (or when the callback was invoked	1101	As soon as the callback is invoked (or when the callback was invoked
751	before C<rouse_wait>), it will return the arguments originally passed to	1102	before C<rouse_wait>), it will return the arguments originally passed to
752	the rouse callback. In scalar context, that means you get the I<last>	1103	the rouse callback. In scalar context, that means you get the I<last>
753	argument, just as if C<rouse_wait> had a C<return ($a1, $a2, $a3...)>	1104	argument, just as if C<rouse_wait> had a C<return ($a1, $a2, $a3...)>
754	statement at the end.	1105	statement at the end.
755		1106
		1107	You are only allowed to wait once for a given rouse callback.
		1108
756	See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example.	1109	See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example.
757		1110
		1111	As of Coro 6.57, you can reliably wait for a rouse callback in a different
		1112	thread than from where it was created.
		1113
758	=back	1114	=back
759		1115
760	=cut	1116	=cut
		1117
		1118	for my $module (qw(Channel RWLock Semaphore SemaphoreSet Signal Specific)) {
		1119	my $old = defined &{"Coro::$module\::new"} && \&{"Coro::$module\::new"};
		1120
		1121	*{"Coro::$module\::new"} = sub {
		1122	require "Coro/$module.pm";
		1123
		1124	# some modules have their new predefined in State.xs, some don't
		1125	*{"Coro::$module\::new"} = $old
		1126	if $old;
		1127
		1128	goto &{"Coro::$module\::new"}
		1129	};
		1130	}
761		1131
762	1;	1132	1;
763		1133
764	=head1 HOW TO WAIT FOR A CALLBACK	1134	=head1 HOW TO WAIT FOR A CALLBACK
765		1135
766	It is very common for a coro to wait for some callback to be	1136	It is very common for a coro to wait for some callback to be
767	called. This occurs naturally when you use coro in an otherwise	1137	called. This occurs naturally when you use coro in an otherwise
768	event-based program, or when you use event-based libraries.	1138	event-based program, or when you use event-based libraries.
769		1139
770	These typically register a callback for some event, and call that callback	1140	These typically register a callback for some event, and call that callback
771	when the event occured. In a coro, however, you typically want to	1141	when the event occurred. In a coro, however, you typically want to
772	just wait for the event, simplyifying things.	1142	just wait for the event, simplyifying things.
773		1143
774	For example C<< AnyEvent->child >> registers a callback to be called when	1144	For example C<< AnyEvent->child >> registers a callback to be called when
775	a specific child has exited:	1145	a specific child has exited:
776		1146
…		…
779	But from within a coro, you often just want to write this:	1149	But from within a coro, you often just want to write this:
780		1150
781	my $status = wait_for_child $pid;	1151	my $status = wait_for_child $pid;
782		1152
783	Coro offers two functions specifically designed to make this easy,	1153	Coro offers two functions specifically designed to make this easy,
784	C<Coro::rouse_cb> and C<Coro::rouse_wait>.	1154	C<rouse_cb> and C<rouse_wait>.
785		1155
786	The first function, C<rouse_cb>, generates and returns a callback that,	1156	The first function, C<rouse_cb>, generates and returns a callback that,
787	when invoked, will save its arguments and notify the coro that	1157	when invoked, will save its arguments and notify the coro that
788	created the callback.	1158	created the callback.
789		1159
…		…
795	function mentioned above:	1165	function mentioned above:
796		1166
797	sub wait_for_child($) {	1167	sub wait_for_child($) {
798	my ($pid) = @_;	1168	my ($pid) = @_;
799		1169
800	my $watcher = AnyEvent->child (pid => $pid, cb => Coro::rouse_cb);	1170	my $watcher = AnyEvent->child (pid => $pid, cb => rouse_cb);
801		1171
802	my ($rpid, $rstatus) = Coro::rouse_wait;	1172	my ($rpid, $rstatus) = rouse_wait;
803	$rstatus	1173	$rstatus
804	}	1174	}
805		1175
806	In the case where C<rouse_cb> and C<rouse_wait> are not flexible enough,	1176	In the case where C<rouse_cb> and C<rouse_wait> are not flexible enough,
807	you can roll your own, using C<schedule>:	1177	you can roll your own, using C<schedule> and C<ready>:
808		1178
809	sub wait_for_child($) {	1179	sub wait_for_child($) {
810	my ($pid) = @_;	1180	my ($pid) = @_;
811		1181
812	# store the current coro in $current,	1182	# store the current coro in $current,
…		…
815	my ($done, $rstatus);	1185	my ($done, $rstatus);
816		1186
817	# pass a closure to ->child	1187	# pass a closure to ->child
818	my $watcher = AnyEvent->child (pid => $pid, cb => sub {	1188	my $watcher = AnyEvent->child (pid => $pid, cb => sub {
819	$rstatus = $_[1]; # remember rstatus	1189	$rstatus = $_[1]; # remember rstatus
820	$done = 1; # mark $rstatus as valud	1190	$done = 1; # mark $rstatus as valid
		1191	$current->ready; # wake up the waiting thread
821	});	1192	});
822		1193
823	# wait until the closure has been called	1194	# wait until the closure has been called
824	schedule while !$done;	1195	schedule while !$done;
825		1196
…		…
844	module from the first thread (this requirement might be removed in the	1215	module from the first thread (this requirement might be removed in the
845	future to allow per-thread schedulers, but Coro::State does not yet allow	1216	future to allow per-thread schedulers, but Coro::State does not yet allow
846	this). I recommend disabling thread support and using processes, as having	1217	this). I recommend disabling thread support and using processes, as having
847	the windows process emulation enabled under unix roughly halves perl	1218	the windows process emulation enabled under unix roughly halves perl
848	performance, even when not used.	1219	performance, even when not used.
		1220
		1221	Attempts to use threads created in another emulated process will crash
		1222	("cleanly", with a null pointer exception).
849		1223
850	=item coro switching is not signal safe	1224	=item coro switching is not signal safe
851		1225
852	You must not switch to another coro from within a signal handler (only	1226	You must not switch to another coro from within a signal handler (only
853	relevant with %SIG - most event libraries provide safe signals), I<unless>	1227	relevant with %SIG - most event libraries provide safe signals), I<unless>
…		…
901	processes. What makes it so bad is that on non-windows platforms, you can	1275	processes. What makes it so bad is that on non-windows platforms, you can
902	actually take advantage of custom hardware for this purpose (as evidenced	1276	actually take advantage of custom hardware for this purpose (as evidenced
903	by the forks module, which gives you the (i-) threads API, just much	1277	by the forks module, which gives you the (i-) threads API, just much
904	faster).	1278	faster).
905		1279
906	Sharing data is in the i-threads model is done by transfering data	1280	Sharing data is in the i-threads model is done by transferring data
907	structures between threads using copying semantics, which is very slow -	1281	structures between threads using copying semantics, which is very slow -
908	shared data simply does not exist. Benchmarks using i-threads which are	1282	shared data simply does not exist. Benchmarks using i-threads which are
909	communication-intensive show extremely bad behaviour with i-threads (in	1283	communication-intensive show extremely bad behaviour with i-threads (in
910	fact, so bad that Coro, which cannot take direct advantage of multiple	1284	fact, so bad that Coro, which cannot take direct advantage of multiple
911	CPUs, is often orders of magnitude faster because it shares data using	1285	CPUs, is often orders of magnitude faster because it shares data using
…		…
941		1315
942	XS API: L<Coro::MakeMaker>.	1316	XS API: L<Coro::MakeMaker>.
943		1317
944	Low level Configuration, Thread Environment, Continuations: L<Coro::State>.	1318	Low level Configuration, Thread Environment, Continuations: L<Coro::State>.
945		1319
946	=head1 AUTHOR	1320	=head1 AUTHOR/SUPPORT/CONTACT
947		1321
948	Marc Lehmann <schmorp@schmorp.de>	1322	Marc A. Lehmann <schmorp@schmorp.de>
949	http://home.schmorp.de/	1323	http://software.schmorp.de/pkg/Coro.html
950		1324
951	=cut	1325	=cut
952		1326

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Comparing Coro/Coro.pm (file contents): Revision 1.282 by root, Sun Dec 26 16:23:51 2010 UTC vs. Revision 1.358 by root, Wed Jul 21 06:37:08 2021 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.282 by root, Sun Dec 26 16:23:51 2010 UTC vs.
Revision 1.358 by root, Wed Jul 21 06:37:08 2021 UTC