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

Comparing Coro/Coro.pm (file contents):
Revision 1.287 by root, Sat Feb 19 06:51:22 2011 UTC vs.
Revision 1.311 by root, Fri Nov 30 08:12:37 2012 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	$locked = 1;
…		…
90	} 1, 2, 3;	89	} 1, 2, 3;
91		90
92	This creates a new coro thread and puts it into the ready queue, meaning	91	This creates a new coro thread and puts it into the ready queue, meaning
93	it will run as soon as the CPU is free for it.	92	it will run as soon as the CPU is free for it.
94		93
95	C<async> will return a coro object - you can store this for future	94	C<async> will return a Coro object - you can store this for future
96	reference or ignore it, the thread itself will keep a reference to it's	95	reference or ignore it - a thread that is running, ready to run or waiting
97	thread object - threads are alive on their own.	96	for some event is alive on it's own.
98		97
99	Another way to create a thread is to call the C<new> constructor with a	98	Another way to create a thread is to call the C<new> constructor with a
100	code-reference:	99	code-reference:
101		100
102	new Coro sub {	101	new Coro sub {
…		…
131	A lot can happen after the coro thread has started running. Quite usually,	130	A lot can happen after the coro thread has started running. Quite usually,
132	it will not run to the end in one go (because you could use a function	131	it will not run to the end in one go (because you could use a function
133	instead), but it will give up the CPU regularly because it waits for	132	instead), but it will give up the CPU regularly because it waits for
134	external events.	133	external events.
135		134
136	As long as a coro thread runs, it's coro object is available in the global	135	As long as a coro thread runs, its Coro object is available in the global
137	variable C<$Coro::current>.	136	variable C<$Coro::current>.
138		137
139	The low-level way to give up the CPU is to call the scheduler, which	138	The low-level way to give up the CPU is to call the scheduler, which
140	selects a new coro thread to run:	139	selects a new coro thread to run:
141		140
…		…
196		195
197	async {	196	async {
198	Coro::terminate "return value 1", "return value 2";	197	Coro::terminate "return value 1", "return value 2";
199	};	198	};
200		199
201	And yet another way is to C<< ->cancel >> the coro thread from another	200	And yet another way is to C<< ->cancel >> (or C<< ->safe_cancel >>) the
202	thread:	201	coro thread from another thread:
203		202
204	my $coro = async {	203	my $coro = async {
205	exit 1;	204	exit 1;
206	};	205	};
207		206
208	$coro->cancel; # an also accept values for ->join to retrieve	207	$coro->cancel; # also accepts values for ->join to retrieve
209		208
210	Cancellation I<can> be dangerous - it's a bit like calling C<exit> without	209	Cancellation I<can> be dangerous - it's a bit like calling C<exit> without
211	actually exiting, and might leave C libraries and XS modules in a weird	210	actually exiting, and might leave C libraries and XS modules in a weird
212	state. Unlike other thread implementations, however, Coro is exceptionally	211	state. Unlike other thread implementations, however, Coro is exceptionally
213	safe with regards to cancellation, as perl will always be in a consistent	212	safe with regards to cancellation, as perl will always be in a consistent
214	state.	213	state, and for those cases where you want to do truly marvellous things
		214	with your coro while it is being cancelled - that is, make sure all
		215	cleanup code is executed from the thread being cancelled - there is even a
		216	C<< ->safe_cancel >> method.
215		217
216	So, cancelling a thread that runs in an XS event loop might not be the	218	So, cancelling a thread that runs in an XS event loop might not be the
217	best idea, but any other combination that deals with perl only (cancelling	219	best idea, but any other combination that deals with perl only (cancelling
218	when a thread is in a C<tie> method or an C<AUTOLOAD> for example) is	220	when a thread is in a C<tie> method or an C<AUTOLOAD> for example) is
219	safe.	221	safe.
220		222
		223	Lastly, a coro thread object that isn't referenced is C<< ->cancel >>'ed
		224	automatically - just like other objects in Perl. This is not such a common
		225	case, however - a running thread is referencedy b C<$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
221	=item 5. Cleanup	237	=item 5. Cleanup
222		238
223	Threads will allocate various resources. Most but not all will be returned	239	Threads will allocate various resources. Most but not all will be returned
224	when a thread terminates, during clean-up.	240	when a thread terminates, during clean-up.
225		241
…		…
248	# if we reutrn, or die or get cancelled, here,	264	# if we reutrn, or die or get cancelled, here,
249	# then the semaphore will be "up"ed.	265	# then the semaphore will be "up"ed.
250	};	266	};
251		267
252	The C<Guard::guard> function comes in handy for any custom cleanup you	268	The C<Guard::guard> function comes in handy for any custom cleanup you
253	might want to do:	269	might want to do (but you cannot switch to other coroutines form those
		270	code blocks):
254		271
255	async {	272	async {
256	my $window = new Gtk2::Window "toplevel";	273	my $window = new Gtk2::Window "toplevel";
257	# The window will not be cleaned up automatically, even when $window	274	# The window will not be cleaned up automatically, even when $window
258	# gets freed, so use a guard to ensure it's destruction	275	# gets freed, so use a guard to ensure it's destruction
…		…
271	# if we return or die here, the description will be restored	288	# if we return or die here, the description will be restored
272	}	289	}
273		290
274	=item 6. Viva La Zombie Muerte	291	=item 6. Viva La Zombie Muerte
275		292
276	Even after a thread has terminated and cleaned up it's resources, the coro	293	Even after a thread has terminated and cleaned up its resources, the Coro
277	object still is there and stores the return values of the thread. Only in	294	object still is there and stores the return values of the thread.
278	this state will the coro object be "reference counted" in the normal perl
279	sense: the thread code keeps a reference to it when it is active, but not
280	after it has terminated.
281		295
282	The means the coro object gets freed automatically when the thread has	296	The means the Coro object gets freed automatically when the thread has
283	terminated and cleaned up and there arenot other references.	297	terminated and cleaned up and there arenot other references.
284		298
285	If there are, the coro object will stay around, and you can call C<<	299	If there are, the Coro object will stay around, and you can call C<<
286	->join >> as many times as you wish to retrieve the result values:	300	->join >> as many times as you wish to retrieve the result values:
287		301
288	async {	302	async {
289	print "hi\n";	303	print "hi\n";
290	1	304	1
…		…
328		342
329	our $idle; # idle handler	343	our $idle; # idle handler
330	our $main; # main coro	344	our $main; # main coro
331	our $current; # current coro	345	our $current; # current coro
332		346
333	our $VERSION = 5.37;	347	our $VERSION = "6.10";
334		348
335	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);
336	our %EXPORT_TAGS = (	350	our %EXPORT_TAGS = (
337	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)],
338	);	352	);
…		…
399	our @destroy;	413	our @destroy;
400	our $manager;	414	our $manager;
401		415
402	$manager = new Coro sub {	416	$manager = new Coro sub {
403	while () {	417	while () {
404	Coro::State::cancel shift @destroy	418	_destroy shift @destroy
405	while @destroy;	419	while @destroy;
406		420
407	&schedule;	421	&schedule;
408	}	422	}
409	};	423	};
…		…
543	coro, regardless of priority. This is useful sometimes to ensure	557	coro, regardless of priority. This is useful sometimes to ensure
544	progress is made.	558	progress is made.
545		559
546	=item terminate [arg...]	560	=item terminate [arg...]
547		561
548	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.
549		564
550	=item Coro::on_enter BLOCK, Coro::on_leave BLOCK	565	=item Coro::on_enter BLOCK, Coro::on_leave BLOCK
551		566
552	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
553	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
…		…
709	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
710	unconditionally, as every synchronisation mechanism must protect itself	725	unconditionally, as every synchronisation mechanism must protect itself
711	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
712	that.	727	that.
713		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
714	=item $is_ready = $coro->is_ready	746	=item $is_ready = $coro->is_ready
715		747
716	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
717	object gets destroyed, it will eventually be scheduled by the scheduler.	749	object gets destroyed, it will eventually be scheduled by the scheduler.
718		750
…		…
727	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
728	not ever be scheduled.	760	not ever be scheduled.
729		761
730	=item $coro->cancel (arg...)	762	=item $coro->cancel (arg...)
731		763
732	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
733	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
734	current Coro.	766	current Coro.
735		767
736	=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.
737		773
738	sub cancel {	774	Any cleanup code being run (e.g. from C<guard> blocks) will be run without
739	my $self = shift;	775	a thread context, and is not allowed to switch to other threads. On the
		776	plus side, C<< ->cancel >> will always clean up the thread, no matter
		777	what. If your cleanup code is complex or you want to avoid cancelling a
		778	C-thread that doesn't know how to clean up itself, it can be better to C<<
		779	->throw >> an exception, or use C<< ->safe_cancel >>.
740		780
741	if ($current == $self) {	781	The arguments to C<< ->cancel >> are not copied, but instead will
742	terminate @_;	782	be referenced directly (e.g. if you pass C<$var> and after the call
743	} else {	783	change that variable, then you might change the return values passed to
744	$self->{_status} = [@_];	784	e.g. C<join>, so don't do that).
745	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: $@";
746	}	828	}
747	}	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.
748		836
749	=item $coro->schedule_to	837	=item $coro->schedule_to
750		838
751	Puts the current coro to sleep (like C<Coro::schedule>), but instead	839	Puts the current coro to sleep (like C<Coro::schedule>), but instead
752	of continuing with the next coro from the ready queue, always switch to	840	of continuing with the next coro from the ready queue, always switch to
…		…
771	inside the coro at the next convenient point in time. Otherwise	859	inside the coro at the next convenient point in time. Otherwise
772	clears the exception object.	860	clears the exception object.
773		861
774	Coro will check for the exception each time a schedule-like-function	862	Coro will check for the exception each time a schedule-like-function
775	returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down	863	returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down
776	>>, C<< Coro::Handle->readable >> and so on. Most of these functions	864	>>, C<< Coro::Handle->readable >> and so on. Most of those functions (all
777	detect this case and return early in case an exception is pending.	865	that are part of Coro itself) detect this case and return early in case an
		866	exception is pending.
778		867
779	The exception object will be thrown "as is" with the specified scalar in	868	The exception object will be thrown "as is" with the specified scalar in
780	C<$@>, 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
781	(unlike with C<die>).	870	(unlike with C<die>).
782		871
783	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
784	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
785	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
786	program.	875	might well end the whole program.
787		876
788	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
789	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).
790		879
791	=item $coro->join	880	=item $coro->join
792		881
793	Wait until the coro terminates and return any values given to the	882	Wait until the coro terminates and return any values given to the
794	C<terminate> or C<cancel> functions. C<join> can be called concurrently	883	C<terminate> or C<cancel> functions. C<join> can be called concurrently
795	from multiple coro, and all will be resumed and given the status	884	from multiple threads, and all will be resumed and given the status
796	return once the C<$coro> terminates.	885	return once the C<$coro> terminates.
797		886
798	=cut
799
800	sub join {
801	my $self = shift;
802
803	unless ($self->{_status}) {
804	my $current = $current;
805
806	push @{$self->{_on_destroy}}, sub {
807	$current->ready;
808	undef $current;
809	};
810
811	&schedule while $current;
812	}
813
814	wantarray ? @{$self->{_status}} : $self->{_status}[0];
815	}
816
817	=item $coro->on_destroy (\&cb)	887	=item $coro->on_destroy (\&cb)
818		888
819	Registers a callback that is called when this coro thread gets destroyed,	889	Registers a callback that is called when this coro thread gets destroyed,
820	but before it is joined. The callback gets passed the terminate arguments,	890	that is, after it's resources have been freed but before it is joined. The
		891	callback gets passed the terminate/cancel arguments, if any, and I<must
821	if any, and I<must not> die, under any circumstances.	892	not> die, under any circumstances.
822		893
823	There can be any number of C<on_destroy> callbacks per coro.	894	There can be any number of C<on_destroy> callbacks per coro, and there is
824		895	no way currently to remove a callback once added.
825	=cut
826
827	sub on_destroy {
828	my ($self, $cb) = @_;
829
830	push @{ $self->{_on_destroy} }, $cb;
831	}
832		896
833	=item $oldprio = $coro->prio ($newprio)	897	=item $oldprio = $coro->prio ($newprio)
834		898
835	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
836	coro thread. Higher priority coro get run before lower priority	900	coro thread. Higher priority coro get run before lower priority
…		…
1065	my ($rpid, $rstatus) = Coro::rouse_wait;	1129	my ($rpid, $rstatus) = Coro::rouse_wait;
1066	$rstatus	1130	$rstatus
1067	}	1131	}
1068		1132
1069	In the case where C<rouse_cb> and C<rouse_wait> are not flexible enough,	1133	In the case where C<rouse_cb> and C<rouse_wait> are not flexible enough,
1070	you can roll your own, using C<schedule>:	1134	you can roll your own, using C<schedule> and C<ready>:
1071		1135
1072	sub wait_for_child($) {	1136	sub wait_for_child($) {
1073	my ($pid) = @_;	1137	my ($pid) = @_;
1074		1138
1075	# store the current coro in $current,	1139	# store the current coro in $current,
…		…
1078	my ($done, $rstatus);	1142	my ($done, $rstatus);
1079		1143
1080	# pass a closure to ->child	1144	# pass a closure to ->child
1081	my $watcher = AnyEvent->child (pid => $pid, cb => sub {	1145	my $watcher = AnyEvent->child (pid => $pid, cb => sub {
1082	$rstatus = $_[1]; # remember rstatus	1146	$rstatus = $_[1]; # remember rstatus
1083	$done = 1; # mark $rstatus as valud	1147	$done = 1; # mark $rstatus as valid
		1148	$current->ready; # wake up the waiting thread
1084	});	1149	});
1085		1150
1086	# wait until the closure has been called	1151	# wait until the closure has been called
1087	schedule while !$done;	1152	schedule while !$done;
1088		1153
…		…
1107	module from the first thread (this requirement might be removed in the	1172	module from the first thread (this requirement might be removed in the
1108	future to allow per-thread schedulers, but Coro::State does not yet allow	1173	future to allow per-thread schedulers, but Coro::State does not yet allow
1109	this). I recommend disabling thread support and using processes, as having	1174	this). I recommend disabling thread support and using processes, as having
1110	the windows process emulation enabled under unix roughly halves perl	1175	the windows process emulation enabled under unix roughly halves perl
1111	performance, even when not used.	1176	performance, even when not used.
		1177
		1178	Attempts to use threads created in another emulated process will crash
		1179	("cleanly", with a null pointer exception).
1112		1180
1113	=item coro switching is not signal safe	1181	=item coro switching is not signal safe
1114		1182
1115	You must not switch to another coro from within a signal handler (only	1183	You must not switch to another coro from within a signal handler (only
1116	relevant with %SIG - most event libraries provide safe signals), I<unless>	1184	relevant with %SIG - most event libraries provide safe signals), I<unless>

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Comparing Coro/Coro.pm (file contents): Revision 1.287 by root, Sat Feb 19 06:51:22 2011 UTC vs. Revision 1.311 by root, Fri Nov 30 08:12:37 2012 UTC

Diff Legend

Comparing Coro/Coro.pm (file contents):
Revision 1.287 by root, Sat Feb 19 06:51:22 2011 UTC vs.
Revision 1.311 by root, Fri Nov 30 08:12:37 2012 UTC