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

Comparing Coro/Coro.pm (file contents):
Revision 1.292 by root, Sat Apr 30 05:17:42 2011 UTC vs.
Revision 1.349 by root, Tue Aug 14 16:51:37 2018 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	Yet another way is to C<< ->cancel >> (or C<< ->safe_cancel >>) the coro
202	thread:	201	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	$coro->cancel; # also accepts values for ->join to retrieve
209		208
210	Cancellation I<can> be dangerous - it's a bit like calling C<exit> without	209	Cancellation I<can> be dangerous - it's a bit like calling C<exit> without
211	actually exiting, and might leave C libraries and XS modules in a weird	210	actually exiting, and might leave C libraries and XS modules in a weird
212	state. Unlike other thread implementations, however, Coro is exceptionally	211	state. Unlike other thread implementations, however, Coro is exceptionally
213	safe with regards to cancellation, as perl will always be in a consistent	212	safe with regards to cancellation, as perl will always be in a consistent
214	state.	213	state, and for those cases where you want to do truly marvellous things
		214	with your coro while it is being cancelled - that is, make sure all
		215	cleanup code is executed from the thread being cancelled - there is even a
		216	C<< ->safe_cancel >> method.
215		217
216	So, cancelling a thread that runs in an XS event loop might not be the	218	So, cancelling a thread that runs in an XS event loop might not be the
217	best idea, but any other combination that deals with perl only (cancelling	219	best idea, but any other combination that deals with perl only (cancelling
218	when a thread is in a C<tie> method or an C<AUTOLOAD> for example) is	220	when a thread is in a C<tie> method or an C<AUTOLOAD> for example) is
219	safe.	221	safe.
220		222
		223	Last not least, a coro thread object that isn't referenced is C<<
		224	->cancel >>'ed automatically - just like other objects in Perl. This
		225	is not such a common case, however - a running thread is referencedy by
		226	C<$Coro::current>, a thread ready to run is referenced by the ready queue,
		227	a thread waiting on a lock or semaphore is referenced by being in some
		228	wait list and so on. But a thread that isn't in any of those queues gets
		229	cancelled:
		230
		231	async {
		232	schedule; # cede to other coros, don't go into the ready queue
		233	};
		234
		235	cede;
		236	# now the async above is destroyed, as it is not referenced by anything.
		237
		238	A slightly embellished example might make it clearer:
		239
		240	async {
		241	my $guard = Guard::guard { print "destroyed\n" };
		242	schedule while 1;
		243	};
		244
		245	cede;
		246
		247	Superficially one might not expect any output - since the C<async>
		248	implements an endless loop, the C<$guard> will not be cleaned up. However,
		249	since the thread object returned by C<async> is not stored anywhere, the
		250	thread is initially referenced because it is in the ready queue, when it
		251	runs it is referenced by C<$Coro::current>, but when it calls C<schedule>,
		252	it gets C<cancel>ed causing the guard object to be destroyed (see the next
		253	section), and printing it's message.
		254
		255	If this seems a bit drastic, remember that this only happens when nothing
		256	references the thread anymore, which means there is no way to further
		257	execute it, ever. The only options at this point are leaking the thread,
		258	or cleaning it up, which brings us to...
		259
221	=item 5. Cleanup	260	=item 5. Cleanup
222		261
223	Threads will allocate various resources. Most but not all will be returned	262	Threads will allocate various resources. Most but not all will be returned
224	when a thread terminates, during clean-up.	263	when a thread terminates, during clean-up.
225		264
…		…
243		282
244	my $sem = new Coro::Semaphore;	283	my $sem = new Coro::Semaphore;
245		284
246	async {	285	async {
247	my $lock_guard = $sem->guard;	286	my $lock_guard = $sem->guard;
248	# if we reutrn, or die or get cancelled, here,	287	# if we return, or die or get cancelled, here,
249	# then the semaphore will be "up"ed.	288	# then the semaphore will be "up"ed.
250	};	289	};
251		290
252	The C<Guard::guard> function comes in handy for any custom cleanup you	291	The C<Guard::guard> function comes in handy for any custom cleanup you
253	might want to do:	292	might want to do (but you cannot switch to other coroutines from those
		293	code blocks):
254		294
255	async {	295	async {
256	my $window = new Gtk2::Window "toplevel";	296	my $window = new Gtk2::Window "toplevel";
257	# The window will not be cleaned up automatically, even when $window	297	# The window will not be cleaned up automatically, even when $window
258	# gets freed, so use a guard to ensure it's destruction	298	# gets freed, so use a guard to ensure it's destruction
…		…
271	# if we return or die here, the description will be restored	311	# if we return or die here, the description will be restored
272	}	312	}
273		313
274	=item 6. Viva La Zombie Muerte	314	=item 6. Viva La Zombie Muerte
275		315
276	Even after a thread has terminated and cleaned up it's resources, the coro	316	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	317	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		318
282	The means the coro object gets freed automatically when the thread has	319	When there are no other references, it will simply be cleaned up and
283	terminated and cleaned up and there arenot other references.	320	freed.
284		321
285	If there are, the coro object will stay around, and you can call C<<	322	If there areany references, the Coro object will stay around, and you
286	->join >> as many times as you wish to retrieve the result values:	323	can call C<< ->join >> as many times as you wish to retrieve the result
		324	values:
287		325
288	async {	326	async {
289	print "hi\n";	327	print "hi\n";
290	1	328	1
291	};	329	};
…		…
328		366
329	our $idle; # idle handler	367	our $idle; # idle handler
330	our $main; # main coro	368	our $main; # main coro
331	our $current; # current coro	369	our $current; # current coro
332		370
333	our $VERSION = 5.372;	371	our $VERSION = 6.52;
334		372
335	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub rouse_cb rouse_wait);	373	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub rouse_cb rouse_wait);
336	our %EXPORT_TAGS = (	374	our %EXPORT_TAGS = (
337	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	375	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
338	);	376	);
…		…
343	=over 4	381	=over 4
344		382
345	=item $Coro::main	383	=item $Coro::main
346		384
347	This variable stores the Coro object that represents the main	385	This variable stores the Coro object that represents the main
348	program. While you cna C<ready> it and do most other things you can do to	386	program. While you can C<ready> it and do most other things you can do to
349	coro, it is mainly useful to compare again C<$Coro::current>, to see	387	coro, it is mainly useful to compare again C<$Coro::current>, to see
350	whether you are running in the main program or not.	388	whether you are running in the main program or not.
351		389
352	=cut	390	=cut
353		391
…		…
460	C<async> does. As the coro is being reused, stuff like C<on_destroy>	498	C<async> does. As the coro is being reused, stuff like C<on_destroy>
461	will not work in the expected way, unless you call terminate or cancel,	499	will not work in the expected way, unless you call terminate or cancel,
462	which somehow defeats the purpose of pooling (but is fine in the	500	which somehow defeats the purpose of pooling (but is fine in the
463	exceptional case).	501	exceptional case).
464		502
465	The priority will be reset to C<0> after each run, tracing will be	503	The priority will be reset to C<0> after each run, all C<swap_sv> calls
466	disabled, the description will be reset and the default output filehandle	504	will be undone, tracing will be disabled, the description will be reset
467	gets restored, so you can change all these. Otherwise the coro will	505	and the default output filehandle gets restored, so you can change all
468	be re-used "as-is": most notably if you change other per-coro global	506	these. Otherwise the coro will be re-used "as-is": most notably if you
469	stuff such as C<$/> you I<must needs> revert that change, which is most	507	change other per-coro global stuff such as C<$/> you I<must needs> revert
470	simply done by using local as in: C<< local $/ >>.	508	that change, which is most simply done by using local as in: C<< local $/
		509	>>.
471		510
472	The idle pool size is limited to C<8> idle coros (this can be	511	The idle pool size is limited to C<8> idle coros (this can be
473	adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle	512	adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle
474	coros as required.	513	coros as required.
475		514
…		…
599	# at this place, the timezone is Antarctica/South_Pole,	638	# at this place, the timezone is Antarctica/South_Pole,
600	# without disturbing the TZ of any other coro.	639	# without disturbing the TZ of any other coro.
601	};	640	};
602		641
603	This can be used to localise about any resource (locale, uid, current	642	This can be used to localise about any resource (locale, uid, current
604	working directory etc.) to a block, despite the existance of other	643	working directory etc.) to a block, despite the existence of other
605	coros.	644	coros.
606		645
607	Another interesting example implements time-sliced multitasking using	646	Another interesting example implements time-sliced multitasking using
608	interval timers (this could obviously be optimised, but does the job):	647	interval timers (this could obviously be optimised, but does the job):
609		648
…		…
614	Coro::on_enter {	653	Coro::on_enter {
615	# on entering the thread, we set an VTALRM handler to cede	654	# on entering the thread, we set an VTALRM handler to cede
616	$SIG{VTALRM} = sub { cede };	655	$SIG{VTALRM} = sub { cede };
617	# and then start the interval timer	656	# and then start the interval timer
618	Time::HiRes::setitimer &Time::HiRes::ITIMER_VIRTUAL, 0.01, 0.01;	657	Time::HiRes::setitimer &Time::HiRes::ITIMER_VIRTUAL, 0.01, 0.01;
619	};	658	};
620	Coro::on_leave {	659	Coro::on_leave {
621	# on leaving the thread, we stop the interval timer again	660	# on leaving the thread, we stop the interval timer again
622	Time::HiRes::setitimer &Time::HiRes::ITIMER_VIRTUAL, 0, 0;	661	Time::HiRes::setitimer &Time::HiRes::ITIMER_VIRTUAL, 0, 0;
623	};	662	};
624		663
625	&{+shift};	664	&{+shift};
626	}	665	}
627		666
628	# use like this:	667	# use like this:
629	timeslice {	668	timeslice {
630	# The following is an endless loop that would normally	669	# The following is an endless loop that would normally
631	# monopolise the process. Since it runs in a timesliced	670	# monopolise the process. Since it runs in a timesliced
632	# environment, it will regularly cede to other threads.	671	# environment, it will regularly cede to other threads.
633	while () { }	672	while () { }
634	};	673	};
635		674
636		675
637	=item killall	676	=item killall
638		677
639	Kills/terminates/cancels all coros except the currently running one.	678	Kills/terminates/cancels all coros except the currently running one.
…		…
710	To avoid this, it is best to put a suspended coro into the ready queue	749	To avoid this, it is best to put a suspended coro into the ready queue
711	unconditionally, as every synchronisation mechanism must protect itself	750	unconditionally, as every synchronisation mechanism must protect itself
712	against spurious wakeups, and the one in the Coro family certainly do	751	against spurious wakeups, and the one in the Coro family certainly do
713	that.	752	that.
714		753
		754	=item $state->is_new
		755
		756	Returns true iff this Coro object is "new", i.e. has never been run
		757	yet. Those states basically consist of only the code reference to call and
		758	the arguments, but consumes very little other resources. New states will
		759	automatically get assigned a perl interpreter when they are transferred to.
		760
		761	=item $state->is_zombie
		762
		763	Returns true iff the Coro object has been cancelled, i.e.
		764	it's resources freed because they were C<cancel>'ed, C<terminate>'d,
		765	C<safe_cancel>'ed or simply went out of scope.
		766
		767	The name "zombie" stems from UNIX culture, where a process that has
		768	exited and only stores and exit status and no other resources is called a
		769	"zombie".
		770
715	=item $is_ready = $coro->is_ready	771	=item $is_ready = $coro->is_ready
716		772
717	Returns true iff the Coro object is in the ready queue. Unless the Coro	773	Returns true iff the Coro object is in the ready queue. Unless the Coro
718	object gets destroyed, it will eventually be scheduled by the scheduler.	774	object gets destroyed, it will eventually be scheduled by the scheduler.
719		775
…		…
726	=item $is_suspended = $coro->is_suspended	782	=item $is_suspended = $coro->is_suspended
727		783
728	Returns true iff this Coro object has been suspended. Suspended Coros will	784	Returns true iff this Coro object has been suspended. Suspended Coros will
729	not ever be scheduled.	785	not ever be scheduled.
730		786
731	=item $coro->cancel (arg...)	787	=item $coro->cancel ($arg...)
732		788
733	Terminates the given Coro object and makes it return the given arguments as	789	Terminate the given Coro thread and make it return the given arguments as
734	status (default: an empty list). Never returns if the Coro is the	790	status (default: an empty list). Never returns if the Coro is the
735	current Coro.	791	current Coro.
736		792
737	The arguments are not copied, but instead will be referenced directly	793	This is a rather brutal way to free a coro, with some limitations - if
738	(e.g. if you pass C<$var> and after the call change that variable, then	794	the thread is inside a C callback that doesn't expect to be canceled,
739	you might change the return values passed to e.g. C<join>, so don't do	795	bad things can happen, or if the cancelled thread insists on running
740	that).	796	complicated cleanup handlers that rely on its thread context, things will
		797	not work.
		798
		799	Any cleanup code being run (e.g. from C<guard> blocks, destructors and so
		800	on) will be run without a thread context, and is not allowed to switch
		801	to other threads. A common mistake is to call C<< ->cancel >> from a
		802	destructor called by die'ing inside the thread to be cancelled for
		803	example.
		804
		805	On the plus side, C<< ->cancel >> will always clean up the thread, no
		806	matter what. If your cleanup code is complex or you want to avoid
		807	cancelling a C-thread that doesn't know how to clean up itself, it can be
		808	better to C<< ->throw >> an exception, or use C<< ->safe_cancel >>.
		809
		810	The arguments to C<< ->cancel >> are not copied, but instead will
		811	be referenced directly (e.g. if you pass C<$var> and after the call
		812	change that variable, then you might change the return values passed to
		813	e.g. C<join>, so don't do that).
741		814
742	The resources of the Coro are usually freed (or destructed) before this	815	The resources of the Coro are usually freed (or destructed) before this
743	call returns, but this can be delayed for an indefinite amount of time, as	816	call returns, but this can be delayed for an indefinite amount of time, as
744	in some cases the manager thread has to run first to actually destruct the	817	in some cases the manager thread has to run first to actually destruct the
745	Coro object.	818	Coro object.
746		819
		820	=item $coro->safe_cancel ($arg...)
		821
		822	Works mostly like C<< ->cancel >>, but is inherently "safer", and
		823	consequently, can fail with an exception in cases the thread is not in a
		824	cancellable state. Essentially, C<< ->safe_cancel >> is a C<< ->cancel >>
		825	with extra checks before canceling.
		826
		827	It works a bit like throwing an exception that cannot be caught -
		828	specifically, it will clean up the thread from within itself, so all
		829	cleanup handlers (e.g. C<guard> blocks) are run with full thread
		830	context and can block if they wish. The downside is that there is no
		831	guarantee that the thread can be cancelled when you call this method, and
		832	therefore, it might fail. It is also considerably slower than C<cancel> or
		833	C<terminate>.
		834
		835	A thread is in a safe-cancellable state if it either has never been run
		836	yet, has already been canceled/terminated or otherwise destroyed, or has
		837	no C context attached and is inside an SLF function.
		838
		839	The first two states are trivial - a thread that hasnot started or has
		840	already finished is safe to cancel.
		841
		842	The last state basically means that the thread isn't currently inside a
		843	perl callback called from some C function (usually via some XS modules)
		844	and isn't currently executing inside some C function itself (via Coro's XS
		845	API).
		846
		847	This call returns true when it could cancel the thread, or croaks with an
		848	error otherwise (i.e. it either returns true or doesn't return at all).
		849
		850	Why the weird interface? Well, there are two common models on how and
		851	when to cancel things. In the first, you have the expectation that your
		852	coro thread can be cancelled when you want to cancel it - if the thread
		853	isn't cancellable, this would be a bug somewhere, so C<< ->safe_cancel >>
		854	croaks to notify of the bug.
		855
		856	In the second model you sometimes want to ask nicely to cancel a thread,
		857	but if it's not a good time, well, then don't cancel. This can be done
		858	relatively easy like this:
		859
		860	if (! eval { $coro->safe_cancel }) {
		861	warn "unable to cancel thread: $@";
		862	}
		863
		864	However, what you never should do is first try to cancel "safely" and
		865	if that fails, cancel the "hard" way with C<< ->cancel >>. That makes
		866	no sense: either you rely on being able to execute cleanup code in your
		867	thread context, or you don't. If you do, then C<< ->safe_cancel >> is the
		868	only way, and if you don't, then C<< ->cancel >> is always faster and more
		869	direct.
		870
747	=item $coro->schedule_to	871	=item $coro->schedule_to
748		872
749	Puts the current coro to sleep (like C<Coro::schedule>), but instead	873	Puts the current coro to sleep (like C<Coro::schedule>), but instead
750	of continuing with the next coro from the ready queue, always switch to	874	of continuing with the next coro from the ready queue, always switch to
751	the given coro object (regardless of priority etc.). The readyness	875	the given coro object (regardless of priority etc.). The readyness
…		…
769	inside the coro at the next convenient point in time. Otherwise	893	inside the coro at the next convenient point in time. Otherwise
770	clears the exception object.	894	clears the exception object.
771		895
772	Coro will check for the exception each time a schedule-like-function	896	Coro will check for the exception each time a schedule-like-function
773	returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down	897	returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down
774	>>, C<< Coro::Handle->readable >> and so on. Most of these functions	898	>>, C<< Coro::Handle->readable >> and so on. Most of those functions (all
775	detect this case and return early in case an exception is pending.	899	that are part of Coro itself) detect this case and return early in case an
		900	exception is pending.
776		901
777	The exception object will be thrown "as is" with the specified scalar in	902	The exception object will be thrown "as is" with the specified scalar in
778	C<$@>, i.e. if it is a string, no line number or newline will be appended	903	C<$@>, i.e. if it is a string, no line number or newline will be appended
779	(unlike with C<die>).	904	(unlike with C<die>).
780		905
781	This can be used as a softer means than C<cancel> to ask a coro to	906	This can be used as a softer means than either C<cancel> or C<safe_cancel
782	end itself, although there is no guarantee that the exception will lead to	907	>to ask a coro to end itself, although there is no guarantee that the
783	termination, and if the exception isn't caught it might well end the whole	908	exception will lead to termination, and if the exception isn't caught it
784	program.	909	might well end the whole program.
785		910
786	You might also think of C<throw> as being the moral equivalent of	911	You might also think of C<throw> as being the moral equivalent of
787	C<kill>ing a coro with a signal (in this case, a scalar).	912	C<kill>ing a coro with a signal (in this case, a scalar).
788		913
789	=item $coro->join	914	=item $coro->join
…		…
791	Wait until the coro terminates and return any values given to the	916	Wait until the coro terminates and return any values given to the
792	C<terminate> or C<cancel> functions. C<join> can be called concurrently	917	C<terminate> or C<cancel> functions. C<join> can be called concurrently
793	from multiple threads, and all will be resumed and given the status	918	from multiple threads, and all will be resumed and given the status
794	return once the C<$coro> terminates.	919	return once the C<$coro> terminates.
795		920
796	=cut
797
798	sub join {
799	my $self = shift;
800
801	unless ($self->{_status}) {
802	my $current = $current;
803
804	push @{$self->{_on_destroy}}, sub {
805	$current->ready;
806	undef $current;
807	};
808
809	&schedule while $current;
810	}
811
812	wantarray ? @{$self->{_status}} : $self->{_status}[0];
813	}
814
815	=item $coro->on_destroy (\&cb)	921	=item $coro->on_destroy (\&cb)
816		922
817	Registers a callback that is called when this coro thread gets destroyed,	923	Registers a callback that is called when this coro thread gets destroyed,
818	but before it is joined. The callback gets passed the terminate arguments,	924	that is, after it's resources have been freed but before it is joined. The
		925	callback gets passed the terminate/cancel arguments, if any, and I<must
819	if any, and I<must not> die, under any circumstances.	926	not> die, under any circumstances.
820		927
821	There can be any number of C<on_destroy> callbacks per coro.	928	There can be any number of C<on_destroy> callbacks per coro, and there is
822		929	currently no way to remove a callback once added.
823	=cut
824
825	sub on_destroy {
826	my ($self, $cb) = @_;
827
828	push @{ $self->{_on_destroy} }, $cb;
829	}
830		930
831	=item $oldprio = $coro->prio ($newprio)	931	=item $oldprio = $coro->prio ($newprio)
832		932
833	Sets (or gets, if the argument is missing) the priority of the	933	Sets (or gets, if the argument is missing) the priority of the
834	coro thread. Higher priority coro get run before lower priority	934	coro thread. Higher priority coro get run before lower priority
…		…
861	coro thread. This is just a free-form string you can associate with a	961	coro thread. This is just a free-form string you can associate with a
862	coro.	962	coro.
863		963
864	This method simply sets the C<< $coro->{desc} >> member to the given	964	This method simply sets the C<< $coro->{desc} >> member to the given
865	string. You can modify this member directly if you wish, and in fact, this	965	string. You can modify this member directly if you wish, and in fact, this
866	is often preferred to indicate major processing states that cna then be	966	is often preferred to indicate major processing states that can then be
867	seen for example in a L<Coro::Debug> session:	967	seen for example in a L<Coro::Debug> session:
868		968
869	sub my_long_function {	969	sub my_long_function {
870	local $Coro::current->{desc} = "now in my_long_function";	970	local $Coro::current->{desc} = "now in my_long_function";
871	...	971	...
…		…
926	otherwise you might suffer from crashes or worse. The only event library	1026	otherwise you might suffer from crashes or worse. The only event library
927	currently known that is safe to use without C<unblock_sub> is L<EV> (but	1027	currently known that is safe to use without C<unblock_sub> is L<EV> (but
928	you might still run into deadlocks if all event loops are blocked).	1028	you might still run into deadlocks if all event loops are blocked).
929		1029
930	Coro will try to catch you when you block in the event loop	1030	Coro will try to catch you when you block in the event loop
931	("FATAL:$Coro::IDLE blocked itself"), but this is just best effort and	1031	("FATAL: $Coro::idle blocked itself"), but this is just best effort and
932	only works when you do not run your own event loop.	1032	only works when you do not run your own event loop.
933		1033
934	This function allows your callbacks to block by executing them in another	1034	This function allows your callbacks to block by executing them in another
935	coro where it is safe to block. One example where blocking is handy	1035	coro where it is safe to block. One example where blocking is handy
936	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to	1036	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
…		…
1027	It is very common for a coro to wait for some callback to be	1127	It is very common for a coro to wait for some callback to be
1028	called. This occurs naturally when you use coro in an otherwise	1128	called. This occurs naturally when you use coro in an otherwise
1029	event-based program, or when you use event-based libraries.	1129	event-based program, or when you use event-based libraries.
1030		1130
1031	These typically register a callback for some event, and call that callback	1131	These typically register a callback for some event, and call that callback
1032	when the event occured. In a coro, however, you typically want to	1132	when the event occurred. In a coro, however, you typically want to
1033	just wait for the event, simplyifying things.	1133	just wait for the event, simplyifying things.
1034		1134
1035	For example C<< AnyEvent->child >> registers a callback to be called when	1135	For example C<< AnyEvent->child >> registers a callback to be called when
1036	a specific child has exited:	1136	a specific child has exited:
1037		1137
…		…
1040	But from within a coro, you often just want to write this:	1140	But from within a coro, you often just want to write this:
1041		1141
1042	my $status = wait_for_child $pid;	1142	my $status = wait_for_child $pid;
1043		1143
1044	Coro offers two functions specifically designed to make this easy,	1144	Coro offers two functions specifically designed to make this easy,
1045	C<Coro::rouse_cb> and C<Coro::rouse_wait>.	1145	C<rouse_cb> and C<rouse_wait>.
1046		1146
1047	The first function, C<rouse_cb>, generates and returns a callback that,	1147	The first function, C<rouse_cb>, generates and returns a callback that,
1048	when invoked, will save its arguments and notify the coro that	1148	when invoked, will save its arguments and notify the coro that
1049	created the callback.	1149	created the callback.
1050		1150
…		…
1056	function mentioned above:	1156	function mentioned above:
1057		1157
1058	sub wait_for_child($) {	1158	sub wait_for_child($) {
1059	my ($pid) = @_;	1159	my ($pid) = @_;
1060		1160
1061	my $watcher = AnyEvent->child (pid => $pid, cb => Coro::rouse_cb);	1161	my $watcher = AnyEvent->child (pid => $pid, cb => rouse_cb);
1062		1162
1063	my ($rpid, $rstatus) = Coro::rouse_wait;	1163	my ($rpid, $rstatus) = rouse_wait;
1064	$rstatus	1164	$rstatus
1065	}	1165	}
1066		1166
1067	In the case where C<rouse_cb> and C<rouse_wait> are not flexible enough,	1167	In the case where C<rouse_cb> and C<rouse_wait> are not flexible enough,
1068	you can roll your own, using C<schedule>:	1168	you can roll your own, using C<schedule> and C<ready>:
1069		1169
1070	sub wait_for_child($) {	1170	sub wait_for_child($) {
1071	my ($pid) = @_;	1171	my ($pid) = @_;
1072		1172
1073	# store the current coro in $current,	1173	# store the current coro in $current,
…		…
1076	my ($done, $rstatus);	1176	my ($done, $rstatus);
1077		1177
1078	# pass a closure to ->child	1178	# pass a closure to ->child
1079	my $watcher = AnyEvent->child (pid => $pid, cb => sub {	1179	my $watcher = AnyEvent->child (pid => $pid, cb => sub {
1080	$rstatus = $_[1]; # remember rstatus	1180	$rstatus = $_[1]; # remember rstatus
1081	$done = 1; # mark $rstatus as valud	1181	$done = 1; # mark $rstatus as valid
		1182	$current->ready; # wake up the waiting thread
1082	});	1183	});
1083		1184
1084	# wait until the closure has been called	1185	# wait until the closure has been called
1085	schedule while !$done;	1186	schedule while !$done;
1086		1187
…		…
1105	module from the first thread (this requirement might be removed in the	1206	module from the first thread (this requirement might be removed in the
1106	future to allow per-thread schedulers, but Coro::State does not yet allow	1207	future to allow per-thread schedulers, but Coro::State does not yet allow
1107	this). I recommend disabling thread support and using processes, as having	1208	this). I recommend disabling thread support and using processes, as having
1108	the windows process emulation enabled under unix roughly halves perl	1209	the windows process emulation enabled under unix roughly halves perl
1109	performance, even when not used.	1210	performance, even when not used.
		1211
		1212	Attempts to use threads created in another emulated process will crash
		1213	("cleanly", with a null pointer exception).
1110		1214
1111	=item coro switching is not signal safe	1215	=item coro switching is not signal safe
1112		1216
1113	You must not switch to another coro from within a signal handler (only	1217	You must not switch to another coro from within a signal handler (only
1114	relevant with %SIG - most event libraries provide safe signals), I<unless>	1218	relevant with %SIG - most event libraries provide safe signals), I<unless>
…		…
1162	processes. What makes it so bad is that on non-windows platforms, you can	1266	processes. What makes it so bad is that on non-windows platforms, you can
1163	actually take advantage of custom hardware for this purpose (as evidenced	1267	actually take advantage of custom hardware for this purpose (as evidenced
1164	by the forks module, which gives you the (i-) threads API, just much	1268	by the forks module, which gives you the (i-) threads API, just much
1165	faster).	1269	faster).
1166		1270
1167	Sharing data is in the i-threads model is done by transfering data	1271	Sharing data is in the i-threads model is done by transferring data
1168	structures between threads using copying semantics, which is very slow -	1272	structures between threads using copying semantics, which is very slow -
1169	shared data simply does not exist. Benchmarks using i-threads which are	1273	shared data simply does not exist. Benchmarks using i-threads which are
1170	communication-intensive show extremely bad behaviour with i-threads (in	1274	communication-intensive show extremely bad behaviour with i-threads (in
1171	fact, so bad that Coro, which cannot take direct advantage of multiple	1275	fact, so bad that Coro, which cannot take direct advantage of multiple
1172	CPUs, is often orders of magnitude faster because it shares data using	1276	CPUs, is often orders of magnitude faster because it shares data using
…		…
1202		1306
1203	XS API: L<Coro::MakeMaker>.	1307	XS API: L<Coro::MakeMaker>.
1204		1308
1205	Low level Configuration, Thread Environment, Continuations: L<Coro::State>.	1309	Low level Configuration, Thread Environment, Continuations: L<Coro::State>.
1206		1310
1207	=head1 AUTHOR	1311	=head1 AUTHOR/SUPPORT/CONTACT
1208		1312
1209	Marc Lehmann <schmorp@schmorp.de>	1313	Marc A. Lehmann <schmorp@schmorp.de>
1210	http://home.schmorp.de/	1314	http://software.schmorp.de/pkg/Coro.html
1211		1315
1212	=cut	1316	=cut
1213		1317

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing Coro/Coro.pm (file contents): Revision 1.292 by root, Sat Apr 30 05:17:42 2011 UTC vs. Revision 1.349 by root, Tue Aug 14 16:51:37 2018 UTC

Diff Legend

Comparing Coro/Coro.pm (file contents):
Revision 1.292 by root, Sat Apr 30 05:17:42 2011 UTC vs.
Revision 1.349 by root, Tue Aug 14 16:51:37 2018 UTC