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

Comparing Coro/Coro.pm (file contents):
Revision 1.244 by root, Sat Dec 13 22:08:13 2008 UTC vs.
Revision 1.268 by root, Thu Oct 1 23:16:27 2009 UTC

…		…
11	print "2\n";	11	print "2\n";
12	cede; # yield back to main	12	cede; # yield back to main
13	print "4\n";	13	print "4\n";
14	};	14	};
15	print "1\n";	15	print "1\n";
16	cede; # yield to coroutine	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;	21	use Coro::Semaphore;
…		…
29	=head1 DESCRIPTION	29	=head1 DESCRIPTION
30		30
31	For a tutorial-style introduction, please read the L<Coro::Intro>	31	For a tutorial-style introduction, please read the L<Coro::Intro>
32	manpage. This manpage mainly contains reference information.	32	manpage. This manpage mainly contains reference information.
33		33
34	This module collection manages continuations in general, most often	34	This module collection manages continuations in general, most often in
35	in the form of cooperative threads (also called coroutines in the	35	the form of cooperative threads (also called coros, or simply "coro"
36	documentation). They are similar to kernel threads but don't (in general)	36	in the documentation). They are similar to kernel threads but don't (in
37	run in parallel at the same time even on SMP machines. The specific flavor	37	general) run in parallel at the same time even on SMP machines. The
38	of thread offered by this module also guarantees you that it will not	38	specific flavor of thread offered by this module also guarantees you that
39	switch between threads unless necessary, at easily-identified points in	39	it will not switch between threads unless necessary, at easily-identified
40	your program, so locking and parallel access are rarely an issue, making	40	points in your program, so locking and parallel access are rarely an
41	thread programming much safer and easier than using other thread models.	41	issue, making thread programming much safer and easier than using other
		42	thread models.
42		43
43	Unlike the so-called "Perl threads" (which are not actually real threads	44	Unlike the so-called "Perl threads" (which are not actually real threads
44	but only the windows process emulation ported to unix), Coro provides a	45	but only the windows process emulation (see section of same name for more
		46	details) ported to unix, and as such act as processes), Coro provides
45	full shared address space, which makes communication between threads	47	a full shared address space, which makes communication between threads
46	very easy. And threads are fast, too: disabling the Windows process	48	very easy. And Coro's threads are fast, too: disabling the Windows
47	emulation code in your perl and using Coro can easily result in a two to	49	process emulation code in your perl and using Coro can easily result in
48	four times speed increase for your programs.	50	a two to four times speed increase for your programs. A parallel matrix
		51	multiplication benchmark runs over 300 times faster on a single core than
		52	perl's pseudo-threads on a quad core using all four cores.
49		53
50	Coro achieves that by supporting multiple running interpreters that share	54	Coro achieves that by supporting multiple running interpreters that share
51	data, which is especially useful to code pseudo-parallel processes and	55	data, which is especially useful to code pseudo-parallel processes and
52	for event-based programming, such as multiple HTTP-GET requests running	56	for event-based programming, such as multiple HTTP-GET requests running
53	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
54	into an event-based environment.	58	into an event-based environment.
55		59
56	In this module, a thread is defined as "callchain + lexical variables +	60	In this module, a thread is defined as "callchain + lexical variables +
57	@_ + $_ + $@ + $/ + C stack), that is, a thread has its own callchain,	61	some package variables + C stack), that is, a thread has its own callchain,
58	its own set of lexicals and its own set of perls most important global	62	its own set of lexicals and its own set of perls most important global
59	variables (see L<Coro::State> for more configuration and background info).	63	variables (see L<Coro::State> for more configuration and background info).
60		64
61	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
62	module family is quite large.	66	module family is quite large.
63		67
64	=cut	68	=cut
65		69
66	package Coro;	70	package Coro;
67		71
68	use strict qw(vars subs);	72	use common::sense;
69	no warnings "uninitialized";	73
		74	use Carp ();
		75
		76	use Guard ();
70		77
71	use Coro::State;	78	use Coro::State;
72		79
73	use base qw(Coro::State Exporter);	80	use base qw(Coro::State Exporter);
74		81
75	our $idle; # idle handler	82	our $idle; # idle handler
76	our $main; # main coroutine	83	our $main; # main coro
77	our $current; # current coroutine	84	our $current; # current coro
78		85
79	our $VERSION = 5.13;	86	our $VERSION = 5.17;
80		87
81	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);	88	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
82	our %EXPORT_TAGS = (	89	our %EXPORT_TAGS = (
83	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	90	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
84	);	91	);
…		…
88		95
89	=over 4	96	=over 4
90		97
91	=item $Coro::main	98	=item $Coro::main
92		99
93	This variable stores the coroutine object that represents the main	100	This variable stores the Coro object that represents the main
94	program. While you cna C<ready> it and do most other things you can do to	101	program. While you cna C<ready> it and do most other things you can do to
95	coroutines, it is mainly useful to compare again C<$Coro::current>, to see	102	coro, it is mainly useful to compare again C<$Coro::current>, to see
96	whether you are running in the main program or not.	103	whether you are running in the main program or not.
97		104
98	=cut	105	=cut
99		106
100	# $main is now being initialised by Coro::State	107	# $main is now being initialised by Coro::State
101		108
102	=item $Coro::current	109	=item $Coro::current
103		110
104	The coroutine object representing the current coroutine (the last	111	The Coro object representing the current coro (the last
105	coroutine that the Coro scheduler switched to). The initial value is	112	coro that the Coro scheduler switched to). The initial value is
106	C<$Coro::main> (of course).	113	C<$Coro::main> (of course).
107		114
108	This variable is B<strictly> I<read-only>. You can take copies of the	115	This variable is B<strictly> I<read-only>. You can take copies of the
109	value stored in it and use it as any other coroutine object, but you must	116	value stored in it and use it as any other Coro object, but you must
110	not otherwise modify the variable itself.	117	not otherwise modify the variable itself.
111		118
112	=cut	119	=cut
113		120
114	sub current() { $current } # [DEPRECATED]	121	sub current() { $current } # [DEPRECATED]
…		…
117		124
118	This variable is mainly useful to integrate Coro into event loops. It is	125	This variable is mainly useful to integrate Coro into event loops. It is
119	usually better to rely on L<Coro::AnyEvent> or L<Coro::EV>, as this is	126	usually better to rely on L<Coro::AnyEvent> or L<Coro::EV>, as this is
120	pretty low-level functionality.	127	pretty low-level functionality.
121		128
122	This variable stores either a coroutine or a callback.	129	This variable stores either a Coro object or a callback.
123		130
124	If it is a callback, the it is called whenever the scheduler finds no	131	If it is a callback, the it is called whenever the scheduler finds no
125	ready coroutines to run. The default implementation prints "FATAL:	132	ready coros to run. The default implementation prints "FATAL:
126	deadlock detected" and exits, because the program has no other way to	133	deadlock detected" and exits, because the program has no other way to
127	continue.	134	continue.
128		135
129	If it is a coroutine object, then this object will be readied (without	136	If it is a coro object, then this object will be readied (without
130	invoking any ready hooks, however) when the scheduler finds no other ready	137	invoking any ready hooks, however) when the scheduler finds no other ready
131	coroutines to run.	138	coros to run.
132		139
133	This hook is overwritten by modules such as C<Coro::EV> and	140	This hook is overwritten by modules such as C<Coro::EV> and
134	C<Coro::AnyEvent> to wait on an external event that hopefully wake up a	141	C<Coro::AnyEvent> to wait on an external event that hopefully wake up a
135	coroutine so the scheduler can run it.	142	coro so the scheduler can run it.
136		143
137	Note that the callback I<must not>, under any circumstances, block	144	Note that the callback I<must not>, under any circumstances, block
138	the current coroutine. Normally, this is achieved by having an "idle	145	the current coro. Normally, this is achieved by having an "idle
139	coroutine" that calls the event loop and then blocks again, and then	146	coro" that calls the event loop and then blocks again, and then
140	readying that coroutine in the idle handler, or by simply placing the idle	147	readying that coro in the idle handler, or by simply placing the idle
141	coroutine in this variable.	148	coro in this variable.
142		149
143	See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this	150	See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this
144	technique.	151	technique.
145		152
146	Please note that if your callback recursively invokes perl (e.g. for event	153	Please note that if your callback recursively invokes perl (e.g. for event
147	handlers), then it must be prepared to be called recursively itself.	154	handlers), then it must be prepared to be called recursively itself.
148		155
149	=cut	156	=cut
150		157
151	$idle = sub {	158	$idle = sub {
152	require Carp;	159	warn "oi\n";#d#
153	Carp::croak ("FATAL: deadlock detected");	160	Carp::confess ("FATAL: deadlock detected");
154	};	161	};
155		162
156	# this coroutine is necessary because a coroutine	163	# this coro is necessary because a coro
157	# cannot destroy itself.	164	# cannot destroy itself.
158	our @destroy;	165	our @destroy;
159	our $manager;	166	our $manager;
160		167
161	$manager = new Coro sub {	168	$manager = new Coro sub {
162	while () {	169	while () {
163	Coro::_cancel shift @destroy	170	Coro::State::cancel shift @destroy
164	while @destroy;	171	while @destroy;
165		172
166	&schedule;	173	&schedule;
167	}	174	}
168	};	175	};
169	$manager->{desc} = "[coro manager]";	176	$manager->{desc} = "[coro manager]";
170	$manager->prio (PRIO_MAX);	177	$manager->prio (PRIO_MAX);
171		178
172	=back	179	=back
173		180
174	=head1 SIMPLE COROUTINE CREATION	181	=head1 SIMPLE CORO CREATION
175		182
176	=over 4	183	=over 4
177		184
178	=item async { ... } [@args...]	185	=item async { ... } [@args...]
179		186
180	Create a new coroutine and return its coroutine object (usually	187	Create a new coro and return its Coro object (usually
181	unused). The coroutine will be put into the ready queue, so	188	unused). The coro will be put into the ready queue, so
182	it will start running automatically on the next scheduler run.	189	it will start running automatically on the next scheduler run.
183		190
184	The first argument is a codeblock/closure that should be executed in the	191	The first argument is a codeblock/closure that should be executed in the
185	coroutine. When it returns argument returns the coroutine is automatically	192	coro. When it returns argument returns the coro is automatically
186	terminated.	193	terminated.
187		194
188	The remaining arguments are passed as arguments to the closure.	195	The remaining arguments are passed as arguments to the closure.
189		196
190	See the C<Coro::State::new> constructor for info about the coroutine	197	See the C<Coro::State::new> constructor for info about the coro
191	environment in which coroutines are executed.	198	environment in which coro are executed.
192		199
193	Calling C<exit> in a coroutine will do the same as calling exit outside	200	Calling C<exit> in a coro will do the same as calling exit outside
194	the coroutine. Likewise, when the coroutine dies, the program will exit,	201	the coro. Likewise, when the coro dies, the program will exit,
195	just as it would in the main program.	202	just as it would in the main program.
196		203
197	If you do not want that, you can provide a default C<die> handler, or	204	If you do not want that, you can provide a default C<die> handler, or
198	simply avoid dieing (by use of C<eval>).	205	simply avoid dieing (by use of C<eval>).
199		206
200	Example: Create a new coroutine that just prints its arguments.	207	Example: Create a new coro that just prints its arguments.
201		208
202	async {	209	async {
203	print "@_\n";	210	print "@_\n";
204	} 1,2,3,4;	211	} 1,2,3,4;
205		212
206	=cut
207
208	sub async(&@) {
209	my $coro = new Coro @_;
210	$coro->ready;
211	$coro
212	}
213
214	=item async_pool { ... } [@args...]	213	=item async_pool { ... } [@args...]
215		214
216	Similar to C<async>, but uses a coroutine pool, so you should not call	215	Similar to C<async>, but uses a coro pool, so you should not call
217	terminate or join on it (although you are allowed to), and you get a	216	terminate or join on it (although you are allowed to), and you get a
218	coroutine that might have executed other code already (which can be good	217	coro that might have executed other code already (which can be good
219	or bad :).	218	or bad :).
220		219
221	On the plus side, this function is about twice as fast as creating (and	220	On the plus side, this function is about twice as fast as creating (and
222	destroying) a completely new coroutine, so if you need a lot of generic	221	destroying) a completely new coro, so if you need a lot of generic
223	coroutines in quick successsion, use C<async_pool>, not C<async>.	222	coros in quick successsion, use C<async_pool>, not C<async>.
224		223
225	The code block is executed in an C<eval> context and a warning will be	224	The code block is executed in an C<eval> context and a warning will be
226	issued in case of an exception instead of terminating the program, as	225	issued in case of an exception instead of terminating the program, as
227	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>	226	C<async> does. As the coro is being reused, stuff like C<on_destroy>
228	will not work in the expected way, unless you call terminate or cancel,	227	will not work in the expected way, unless you call terminate or cancel,
229	which somehow defeats the purpose of pooling (but is fine in the	228	which somehow defeats the purpose of pooling (but is fine in the
230	exceptional case).	229	exceptional case).
231		230
232	The priority will be reset to C<0> after each run, tracing will be	231	The priority will be reset to C<0> after each run, tracing will be
233	disabled, the description will be reset and the default output filehandle	232	disabled, the description will be reset and the default output filehandle
234	gets restored, so you can change all these. Otherwise the coroutine will	233	gets restored, so you can change all these. Otherwise the coro will
235	be re-used "as-is": most notably if you change other per-coroutine global	234	be re-used "as-is": most notably if you change other per-coro global
236	stuff such as C<$/> you I<must needs> revert that change, which is most	235	stuff such as C<$/> you I<must needs> revert that change, which is most
237	simply done by using local as in: C<< local $/ >>.	236	simply done by using local as in: C<< local $/ >>.
238		237
239	The idle pool size is limited to C<8> idle coroutines (this can be	238	The idle pool size is limited to C<8> idle coros (this can be
240	adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle	239	adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle
241	coros as required.	240	coros as required.
242		241
243	If you are concerned about pooled coroutines growing a lot because a	242	If you are concerned about pooled coros growing a lot because a
244	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool	243	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
245	{ terminate }> once per second or so to slowly replenish the pool. In	244	{ terminate }> once per second or so to slowly replenish the pool. In
246	addition to that, when the stacks used by a handler grows larger than 32kb	245	addition to that, when the stacks used by a handler grows larger than 32kb
247	(adjustable via $Coro::POOL_RSS) it will also be destroyed.	246	(adjustable via $Coro::POOL_RSS) it will also be destroyed.
248		247
…		…
265	=back	264	=back
266		265
267	=head1 STATIC METHODS	266	=head1 STATIC METHODS
268		267
269	Static methods are actually functions that implicitly operate on the	268	Static methods are actually functions that implicitly operate on the
270	current coroutine.	269	current coro.
271		270
272	=over 4	271	=over 4
273		272
274	=item schedule	273	=item schedule
275		274
276	Calls the scheduler. The scheduler will find the next coroutine that is	275	Calls the scheduler. The scheduler will find the next coro that is
277	to be run from the ready queue and switches to it. The next coroutine	276	to be run from the ready queue and switches to it. The next coro
278	to be run is simply the one with the highest priority that is longest	277	to be run is simply the one with the highest priority that is longest
279	in its ready queue. If there is no coroutine ready, it will clal the	278	in its ready queue. If there is no coro ready, it will clal the
280	C<$Coro::idle> hook.	279	C<$Coro::idle> hook.
281		280
282	Please note that the current coroutine will I<not> be put into the ready	281	Please note that the current coro will I<not> be put into the ready
283	queue, so calling this function usually means you will never be called	282	queue, so calling this function usually means you will never be called
284	again unless something else (e.g. an event handler) calls C<< ->ready >>,	283	again unless something else (e.g. an event handler) calls C<< ->ready >>,
285	thus waking you up.	284	thus waking you up.
286		285
287	This makes C<schedule> I<the> generic method to use to block the current	286	This makes C<schedule> I<the> generic method to use to block the current
288	coroutine and wait for events: first you remember the current coroutine in	287	coro and wait for events: first you remember the current coro in
289	a variable, then arrange for some callback of yours to call C<< ->ready	288	a variable, then arrange for some callback of yours to call C<< ->ready
290	>> on that once some event happens, and last you call C<schedule> to put	289	>> on that once some event happens, and last you call C<schedule> to put
291	yourself to sleep. Note that a lot of things can wake your coroutine up,	290	yourself to sleep. Note that a lot of things can wake your coro up,
292	so you need to check whether the event indeed happened, e.g. by storing the	291	so you need to check whether the event indeed happened, e.g. by storing the
293	status in a variable.	292	status in a variable.
294		293
295	See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks.	294	See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks.
296		295
297	=item cede	296	=item cede
298		297
299	"Cede" to other coroutines. This function puts the current coroutine into	298	"Cede" to other coros. This function puts the current coro into
300	the ready queue and calls C<schedule>, which has the effect of giving	299	the ready queue and calls C<schedule>, which has the effect of giving
301	up the current "timeslice" to other coroutines of the same or higher	300	up the current "timeslice" to other coros of the same or higher
302	priority. Once your coroutine gets its turn again it will automatically be	301	priority. Once your coro gets its turn again it will automatically be
303	resumed.	302	resumed.
304		303
305	This function is often called C<yield> in other languages.	304	This function is often called C<yield> in other languages.
306		305
307	=item Coro::cede_notself	306	=item Coro::cede_notself
308		307
309	Works like cede, but is not exported by default and will cede to I<any>	308	Works like cede, but is not exported by default and will cede to I<any>
310	coroutine, regardless of priority. This is useful sometimes to ensure	309	coro, regardless of priority. This is useful sometimes to ensure
311	progress is made.	310	progress is made.
312		311
313	=item terminate [arg...]	312	=item terminate [arg...]
314		313
315	Terminates the current coroutine with the given status values (see L<cancel>).	314	Terminates the current coro with the given status values (see L<cancel>).
		315
		316	=item Coro::on_enter BLOCK, Coro::on_leave BLOCK
		317
		318	These function install enter and leave winders in the current scope. The
		319	enter block will be executed when on_enter is called and whenever the
		320	current coro is re-entered by the scheduler, while the leave block is
		321	executed whenever the current coro is blocked by the scheduler, and
		322	also when the containing scope is exited (by whatever means, be it exit,
		323	die, last etc.).
		324
		325	I<Neither invoking the scheduler, nor exceptions, are allowed within those
		326	BLOCKs>. That means: do not even think about calling C<die> without an
		327	eval, and do not even think of entering the scheduler in any way.
		328
		329	Since both BLOCKs are tied to the current scope, they will automatically
		330	be removed when the current scope exits.
		331
		332	These functions implement the same concept as C<dynamic-wind> in scheme
		333	does, and are useful when you want to localise some resource to a specific
		334	coro.
		335
		336	They slow down thread switching considerably for coros that use them
		337	(about 40% for a BLOCK with a single assignment, so thread switching is
		338	still reasonably fast if the handlers are fast).
		339
		340	These functions are best understood by an example: The following function
		341	will change the current timezone to "Antarctica/South_Pole", which
		342	requires a call to C<tzset>, but by using C<on_enter> and C<on_leave>,
		343	which remember/change the current timezone and restore the previous
		344	value, respectively, the timezone is only changed for the coro that
		345	installed those handlers.
		346
		347	use POSIX qw(tzset);
		348
		349	async {
		350	my $old_tz; # store outside TZ value here
		351
		352	Coro::on_enter {
		353	$old_tz = $ENV{TZ}; # remember the old value
		354
		355	$ENV{TZ} = "Antarctica/South_Pole";
		356	tzset; # enable new value
		357	};
		358
		359	Coro::on_leave {
		360	$ENV{TZ} = $old_tz;
		361	tzset; # restore old value
		362	};
		363
		364	# at this place, the timezone is Antarctica/South_Pole,
		365	# without disturbing the TZ of any other coro.
		366	};
		367
		368	This can be used to localise about any resource (locale, uid, current
		369	working directory etc.) to a block, despite the existance of other
		370	coros.
		371
		372	Another interesting example implements time-sliced multitasking using
		373	interval timers (this could obviously be optimised, but does the job):
		374
		375	# "timeslice" the given block
		376	sub timeslice(&) {
		377	use Time::HiRes ();
		378
		379	Coro::on_enter {
		380	# on entering the thread, we set an VTALRM handler to cede
		381	$SIG{VTALRM} = sub { cede };
		382	# and then start the interval timer
		383	Time::HiRes::setitimer &Time::HiRes::ITIMER_VIRTUAL, 0.01, 0.01;
		384	};
		385	Coro::on_leave {
		386	# on leaving the thread, we stop the interval timer again
		387	Time::HiRes::setitimer &Time::HiRes::ITIMER_VIRTUAL, 0, 0;
		388	};
		389
		390	&{+shift};
		391	}
		392
		393	# use like this:
		394	timeslice {
		395	# The following is an endless loop that would normally
		396	# monopolise the process. Since it runs in a timesliced
		397	# environment, it will regularly cede to other threads.
		398	while () { }
		399	};
		400
316		401
317	=item killall	402	=item killall
318		403
319	Kills/terminates/cancels all coroutines except the currently running	404	Kills/terminates/cancels all coros except the currently running one.
320	one. This is useful after a fork, either in the child or the parent, as
321	usually only one of them should inherit the running coroutines.
322		405
323	Note that while this will try to free some of the main programs resources,	406	Note that while this will try to free some of the main interpreter
		407	resources if the calling coro isn't the main coro, but one
324	you cannot free all of them, so if a coroutine that is not the main	408	cannot free all of them, so if a coro that is not the main coro
325	program calls this function, there will be some one-time resource leak.	409	calls this function, there will be some one-time resource leak.
326		410
327	=cut	411	=cut
328		412
329	sub killall {	413	sub killall {
330	for (Coro::State::list) {	414	for (Coro::State::list) {
…		…
333	}	417	}
334	}	418	}
335		419
336	=back	420	=back
337		421
338	=head1 COROUTINE OBJECT METHODS	422	=head1 CORO OBJECT METHODS
339		423
340	These are the methods you can call on coroutine objects (or to create	424	These are the methods you can call on coro objects (or to create
341	them).	425	them).
342		426
343	=over 4	427	=over 4
344		428
345	=item new Coro \&sub [, @args...]	429	=item new Coro \&sub [, @args...]
346		430
347	Create a new coroutine and return it. When the sub returns, the coroutine	431	Create a new coro and return it. When the sub returns, the coro
348	automatically terminates as if C<terminate> with the returned values were	432	automatically terminates as if C<terminate> with the returned values were
349	called. To make the coroutine run you must first put it into the ready	433	called. To make the coro run you must first put it into the ready
350	queue by calling the ready method.	434	queue by calling the ready method.
351		435
352	See C<async> and C<Coro::State::new> for additional info about the	436	See C<async> and C<Coro::State::new> for additional info about the
353	coroutine environment.	437	coro environment.
354		438
355	=cut	439	=cut
356		440
357	sub _coro_run {	441	sub _coro_run {
358	terminate &{+shift};	442	terminate &{+shift};
359	}	443	}
360		444
361	=item $success = $coroutine->ready	445	=item $success = $coro->ready
362		446
363	Put the given coroutine into the end of its ready queue (there is one	447	Put the given coro into the end of its ready queue (there is one
364	queue for each priority) and return true. If the coroutine is already in	448	queue for each priority) and return true. If the coro is already in
365	the ready queue, do nothing and return false.	449	the ready queue, do nothing and return false.
366		450
367	This ensures that the scheduler will resume this coroutine automatically	451	This ensures that the scheduler will resume this coro automatically
368	once all the coroutines of higher priority and all coroutines of the same	452	once all the coro of higher priority and all coro of the same
369	priority that were put into the ready queue earlier have been resumed.	453	priority that were put into the ready queue earlier have been resumed.
370		454
		455	=item $coro->suspend
		456
		457	Suspends the specified coro. A suspended coro works just like any other
		458	coro, except that the scheduler will not select a suspended coro for
		459	execution.
		460
		461	Suspending a coro can be useful when you want to keep the coro from
		462	running, but you don't want to destroy it, or when you want to temporarily
		463	freeze a coro (e.g. for debugging) to resume it later.
		464
		465	A scenario for the former would be to suspend all (other) coros after a
		466	fork and keep them alive, so their destructors aren't called, but new
		467	coros can be created.
		468
		469	=item $coro->resume
		470
		471	If the specified coro was suspended, it will be resumed. Note that when
		472	the coro was in the ready queue when it was suspended, it might have been
		473	unreadied by the scheduler, so an activation might have been lost.
		474
		475	To avoid this, it is best to put a suspended coro into the ready queue
		476	unconditionally, as every synchronisation mechanism must protect itself
		477	against spurious wakeups, and the one in the Coro family certainly do
		478	that.
		479
371	=item $is_ready = $coroutine->is_ready	480	=item $is_ready = $coro->is_ready
372		481
373	Return whether the coroutine is currently the ready queue or not,	482	Returns true iff the Coro object is in the ready queue. Unless the Coro
		483	object gets destroyed, it will eventually be scheduled by the scheduler.
374		484
		485	=item $is_running = $coro->is_running
		486
		487	Returns true iff the Coro object is currently running. Only one Coro object
		488	can ever be in the running state (but it currently is possible to have
		489	multiple running Coro::States).
		490
		491	=item $is_suspended = $coro->is_suspended
		492
		493	Returns true iff this Coro object has been suspended. Suspended Coros will
		494	not ever be scheduled.
		495
375	=item $coroutine->cancel (arg...)	496	=item $coro->cancel (arg...)
376		497
377	Terminates the given coroutine and makes it return the given arguments as	498	Terminates the given Coro and makes it return the given arguments as
378	status (default: the empty list). Never returns if the coroutine is the	499	status (default: the empty list). Never returns if the Coro is the
379	current coroutine.	500	current Coro.
380		501
381	=cut	502	=cut
382		503
383	sub cancel {	504	sub cancel {
384	my $self = shift;	505	my $self = shift;
385		506
386	if ($current == $self) {	507	if ($current == $self) {
387	terminate @_;	508	terminate @_;
388	} else {	509	} else {
389	$self->{_status} = [@_];	510	$self->{_status} = [@_];
390	$self->_cancel;	511	Coro::State::cancel $self;
391	}	512	}
392	}	513	}
393		514
394	=item $coroutine->schedule_to	515	=item $coro->schedule_to
395		516
396	Puts the current coroutine to sleep (like C<Coro::schedule>), but instead	517	Puts the current coro to sleep (like C<Coro::schedule>), but instead
397	of continuing with the next coro from the ready queue, always switch to	518	of continuing with the next coro from the ready queue, always switch to
398	the given coroutine object (regardless of priority etc.). The readyness	519	the given coro object (regardless of priority etc.). The readyness
399	state of that coroutine isn't changed.	520	state of that coro isn't changed.
400		521
401	This is an advanced method for special cases - I'd love to hear about any	522	This is an advanced method for special cases - I'd love to hear about any
402	uses for this one.	523	uses for this one.
403		524
404	=item $coroutine->cede_to	525	=item $coro->cede_to
405		526
406	Like C<schedule_to>, but puts the current coroutine into the ready	527	Like C<schedule_to>, but puts the current coro into the ready
407	queue. This has the effect of temporarily switching to the given	528	queue. This has the effect of temporarily switching to the given
408	coroutine, and continuing some time later.	529	coro, and continuing some time later.
409		530
410	This is an advanced method for special cases - I'd love to hear about any	531	This is an advanced method for special cases - I'd love to hear about any
411	uses for this one.	532	uses for this one.
412		533
413	=item $coroutine->throw ([$scalar])	534	=item $coro->throw ([$scalar])
414		535
415	If C<$throw> is specified and defined, it will be thrown as an exception	536	If C<$throw> is specified and defined, it will be thrown as an exception
416	inside the coroutine at the next convenient point in time. Otherwise	537	inside the coro at the next convenient point in time. Otherwise
417	clears the exception object.	538	clears the exception object.
418		539
419	Coro will check for the exception each time a schedule-like-function	540	Coro will check for the exception each time a schedule-like-function
420	returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down	541	returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down
421	>>, C<< Coro::Handle->readable >> and so on. Most of these functions	542	>>, C<< Coro::Handle->readable >> and so on. Most of these functions
…		…
423		544
424	The exception object will be thrown "as is" with the specified scalar in	545	The exception object will be thrown "as is" with the specified scalar in
425	C<$@>, i.e. if it is a string, no line number or newline will be appended	546	C<$@>, i.e. if it is a string, no line number or newline will be appended
426	(unlike with C<die>).	547	(unlike with C<die>).
427		548
428	This can be used as a softer means than C<cancel> to ask a coroutine to	549	This can be used as a softer means than C<cancel> to ask a coro to
429	end itself, although there is no guarantee that the exception will lead to	550	end itself, although there is no guarantee that the exception will lead to
430	termination, and if the exception isn't caught it might well end the whole	551	termination, and if the exception isn't caught it might well end the whole
431	program.	552	program.
432		553
433	You might also think of C<throw> as being the moral equivalent of	554	You might also think of C<throw> as being the moral equivalent of
434	C<kill>ing a coroutine with a signal (in this case, a scalar).	555	C<kill>ing a coro with a signal (in this case, a scalar).
435		556
436	=item $coroutine->join	557	=item $coro->join
437		558
438	Wait until the coroutine terminates and return any values given to the	559	Wait until the coro terminates and return any values given to the
439	C<terminate> or C<cancel> functions. C<join> can be called concurrently	560	C<terminate> or C<cancel> functions. C<join> can be called concurrently
440	from multiple coroutines, and all will be resumed and given the status	561	from multiple coro, and all will be resumed and given the status
441	return once the C<$coroutine> terminates.	562	return once the C<$coro> terminates.
442		563
443	=cut	564	=cut
444		565
445	sub join {	566	sub join {
446	my $self = shift;	567	my $self = shift;
…		…
457	}	578	}
458		579
459	wantarray ? @{$self->{_status}} : $self->{_status}[0];	580	wantarray ? @{$self->{_status}} : $self->{_status}[0];
460	}	581	}
461		582
462	=item $coroutine->on_destroy (\&cb)	583	=item $coro->on_destroy (\&cb)
463		584
464	Registers a callback that is called when this coroutine gets destroyed,	585	Registers a callback that is called when this coro gets destroyed,
465	but before it is joined. The callback gets passed the terminate arguments,	586	but before it is joined. The callback gets passed the terminate arguments,
466	if any, and I<must not> die, under any circumstances.	587	if any, and I<must not> die, under any circumstances.
467		588
468	=cut	589	=cut
469		590
…		…
471	my ($self, $cb) = @_;	592	my ($self, $cb) = @_;
472		593
473	push @{ $self->{_on_destroy} }, $cb;	594	push @{ $self->{_on_destroy} }, $cb;
474	}	595	}
475		596
476	=item $oldprio = $coroutine->prio ($newprio)	597	=item $oldprio = $coro->prio ($newprio)
477		598
478	Sets (or gets, if the argument is missing) the priority of the	599	Sets (or gets, if the argument is missing) the priority of the
479	coroutine. Higher priority coroutines get run before lower priority	600	coro. Higher priority coro get run before lower priority
480	coroutines. Priorities are small signed integers (currently -4 .. +3),	601	coro. Priorities are small signed integers (currently -4 .. +3),
481	that you can refer to using PRIO_xxx constants (use the import tag :prio	602	that you can refer to using PRIO_xxx constants (use the import tag :prio
482	to get then):	603	to get then):
483		604
484	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN	605	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
485	3 > 1 > 0 > -1 > -3 > -4	606	3 > 1 > 0 > -1 > -3 > -4
486		607
487	# set priority to HIGH	608	# set priority to HIGH
488	current->prio(PRIO_HIGH);	609	current->prio (PRIO_HIGH);
489		610
490	The idle coroutine ($Coro::idle) always has a lower priority than any	611	The idle coro ($Coro::idle) always has a lower priority than any
491	existing coroutine.	612	existing coro.
492		613
493	Changing the priority of the current coroutine will take effect immediately,	614	Changing the priority of the current coro will take effect immediately,
494	but changing the priority of coroutines in the ready queue (but not	615	but changing the priority of coro in the ready queue (but not
495	running) will only take effect after the next schedule (of that	616	running) will only take effect after the next schedule (of that
496	coroutine). This is a bug that will be fixed in some future version.	617	coro). This is a bug that will be fixed in some future version.
497		618
498	=item $newprio = $coroutine->nice ($change)	619	=item $newprio = $coro->nice ($change)
499		620
500	Similar to C<prio>, but subtract the given value from the priority (i.e.	621	Similar to C<prio>, but subtract the given value from the priority (i.e.
501	higher values mean lower priority, just as in unix).	622	higher values mean lower priority, just as in unix).
502		623
503	=item $olddesc = $coroutine->desc ($newdesc)	624	=item $olddesc = $coro->desc ($newdesc)
504		625
505	Sets (or gets in case the argument is missing) the description for this	626	Sets (or gets in case the argument is missing) the description for this
506	coroutine. This is just a free-form string you can associate with a	627	coro. This is just a free-form string you can associate with a
507	coroutine.	628	coro.
508		629
509	This method simply sets the C<< $coroutine->{desc} >> member to the given	630	This method simply sets the C<< $coro->{desc} >> member to the given
510	string. You can modify this member directly if you wish.	631	string. You can modify this member directly if you wish.
511		632
512	=cut	633	=cut
513		634
514	sub desc {	635	sub desc {
…		…
528		649
529	=over 4	650	=over 4
530		651
531	=item Coro::nready	652	=item Coro::nready
532		653
533	Returns the number of coroutines that are currently in the ready state,	654	Returns the number of coro that are currently in the ready state,
534	i.e. that can be switched to by calling C<schedule> directory or	655	i.e. that can be switched to by calling C<schedule> directory or
535	indirectly. The value C<0> means that the only runnable coroutine is the	656	indirectly. The value C<0> means that the only runnable coro is the
536	currently running one, so C<cede> would have no effect, and C<schedule>	657	currently running one, so C<cede> would have no effect, and C<schedule>
537	would cause a deadlock unless there is an idle handler that wakes up some	658	would cause a deadlock unless there is an idle handler that wakes up some
538	coroutines.	659	coro.
539		660
540	=item my $guard = Coro::guard { ... }	661	=item my $guard = Coro::guard { ... }
541		662
542	This function still exists, but is deprecated. Please use the	663	This function still exists, but is deprecated. Please use the
543	C<Guard::guard> function instead.	664	C<Guard::guard> function instead.
…		…
550		671
551	This utility function takes a BLOCK or code reference and "unblocks" it,	672	This utility function takes a BLOCK or code reference and "unblocks" it,
552	returning a new coderef. Unblocking means that calling the new coderef	673	returning a new coderef. Unblocking means that calling the new coderef
553	will return immediately without blocking, returning nothing, while the	674	will return immediately without blocking, returning nothing, while the
554	original code ref will be called (with parameters) from within another	675	original code ref will be called (with parameters) from within another
555	coroutine.	676	coro.
556		677
557	The reason this function exists is that many event libraries (such as the	678	The reason this function exists is that many event libraries (such as the
558	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form	679	venerable L<Event\|Event> module) are not thread-safe (a weaker form
559	of reentrancy). This means you must not block within event callbacks,	680	of reentrancy). This means you must not block within event callbacks,
560	otherwise you might suffer from crashes or worse. The only event library	681	otherwise you might suffer from crashes or worse. The only event library
561	currently known that is safe to use without C<unblock_sub> is L<EV>.	682	currently known that is safe to use without C<unblock_sub> is L<EV>.
562		683
563	This function allows your callbacks to block by executing them in another	684	This function allows your callbacks to block by executing them in another
564	coroutine where it is safe to block. One example where blocking is handy	685	coro where it is safe to block. One example where blocking is handy
565	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to	686	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
566	disk, for example.	687	disk, for example.
567		688
568	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when	689	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
569	creating event callbacks that want to block.	690	creating event callbacks that want to block.
570		691
571	If your handler does not plan to block (e.g. simply sends a message to	692	If your handler does not plan to block (e.g. simply sends a message to
572	another coroutine, or puts some other coroutine into the ready queue),	693	another coro, or puts some other coro into the ready queue), there is
573	there is no reason to use C<unblock_sub>.	694	no reason to use C<unblock_sub>.
574		695
575	Note that you also need to use C<unblock_sub> for any other callbacks that	696	Note that you also need to use C<unblock_sub> for any other callbacks that
576	are indirectly executed by any C-based event loop. For example, when you	697	are indirectly executed by any C-based event loop. For example, when you
577	use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it	698	use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it
578	provides callbacks that are the result of some event callback, then you	699	provides callbacks that are the result of some event callback, then you
…		…
612		733
613	=item $cb = Coro::rouse_cb	734	=item $cb = Coro::rouse_cb
614		735
615	Create and return a "rouse callback". That's a code reference that,	736	Create and return a "rouse callback". That's a code reference that,
616	when called, will remember a copy of its arguments and notify the owner	737	when called, will remember a copy of its arguments and notify the owner
617	coroutine of the callback.	738	coro of the callback.
618		739
619	See the next function.	740	See the next function.
620		741
621	=item @args = Coro::rouse_wait [$cb]	742	=item @args = Coro::rouse_wait [$cb]
622		743
623	Wait for the specified rouse callback (or the last one that was created in	744	Wait for the specified rouse callback (or the last one that was created in
624	this coroutine).	745	this coro).
625		746
626	As soon as the callback is invoked (or when the callback was invoked	747	As soon as the callback is invoked (or when the callback was invoked
627	before C<rouse_wait>), it will return the arguments originally passed to	748	before C<rouse_wait>), it will return the arguments originally passed to
628	the rouse callback.	749	the rouse callback. In scalar context, that means you get the I<last>
		750	argument, just as if C<rouse_wait> had a C<return ($a1, $a2, $a3...)>
		751	statement at the end.
629		752
630	See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example.	753	See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example.
631		754
632	=back	755	=back
633		756
…		…
635		758
636	1;	759	1;
637		760
638	=head1 HOW TO WAIT FOR A CALLBACK	761	=head1 HOW TO WAIT FOR A CALLBACK
639		762
640	It is very common for a coroutine to wait for some callback to be	763	It is very common for a coro to wait for some callback to be
641	called. This occurs naturally when you use coroutines in an otherwise	764	called. This occurs naturally when you use coro in an otherwise
642	event-based program, or when you use event-based libraries.	765	event-based program, or when you use event-based libraries.
643		766
644	These typically register a callback for some event, and call that callback	767	These typically register a callback for some event, and call that callback
645	when the event occured. In a coroutine, however, you typically want to	768	when the event occured. In a coro, however, you typically want to
646	just wait for the event, simplyifying things.	769	just wait for the event, simplyifying things.
647		770
648	For example C<< AnyEvent->child >> registers a callback to be called when	771	For example C<< AnyEvent->child >> registers a callback to be called when
649	a specific child has exited:	772	a specific child has exited:
650		773
651	my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... });	774	my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... });
652		775
653	But from withina coroutine, you often just want to write this:	776	But from within a coro, you often just want to write this:
654		777
655	my $status = wait_for_child $pid;	778	my $status = wait_for_child $pid;
656		779
657	Coro offers two functions specifically designed to make this easy,	780	Coro offers two functions specifically designed to make this easy,
658	C<Coro::rouse_cb> and C<Coro::rouse_wait>.	781	C<Coro::rouse_cb> and C<Coro::rouse_wait>.
659		782
660	The first function, C<rouse_cb>, generates and returns a callback that,	783	The first function, C<rouse_cb>, generates and returns a callback that,
661	when invoked, will save its arguments and notify the coroutine that	784	when invoked, will save its arguments and notify the coro that
662	created the callback.	785	created the callback.
663		786
664	The second function, C<rouse_wait>, waits for the callback to be called	787	The second function, C<rouse_wait>, waits for the callback to be called
665	(by calling C<schedule> to go to sleep) and returns the arguments	788	(by calling C<schedule> to go to sleep) and returns the arguments
666	originally passed to the callback.	789	originally passed to the callback.
…		…
681	you can roll your own, using C<schedule>:	804	you can roll your own, using C<schedule>:
682		805
683	sub wait_for_child($) {	806	sub wait_for_child($) {
684	my ($pid) = @_;	807	my ($pid) = @_;
685		808
686	# store the current coroutine in $current,	809	# store the current coro in $current,
687	# and provide result variables for the closure passed to ->child	810	# and provide result variables for the closure passed to ->child
688	my $current = $Coro::current;	811	my $current = $Coro::current;
689	my ($done, $rstatus);	812	my ($done, $rstatus);
690		813
691	# pass a closure to ->child	814	# pass a closure to ->child
…		…
707		830
708	=item fork with pthread backend	831	=item fork with pthread backend
709		832
710	When Coro is compiled using the pthread backend (which isn't recommended	833	When Coro is compiled using the pthread backend (which isn't recommended
711	but required on many BSDs as their libcs are completely broken), then	834	but required on many BSDs as their libcs are completely broken), then
712	coroutines will not survive a fork. There is no known workaround except to	835	coro will not survive a fork. There is no known workaround except to
713	fix your libc and use a saner backend.	836	fix your libc and use a saner backend.
714		837
715	=item perl process emulation ("threads")	838	=item perl process emulation ("threads")
716		839
717	This module is not perl-pseudo-thread-safe. You should only ever use this	840	This module is not perl-pseudo-thread-safe. You should only ever use this
…		…
719	future to allow per-thread schedulers, but Coro::State does not yet allow	842	future to allow per-thread schedulers, but Coro::State does not yet allow
720	this). I recommend disabling thread support and using processes, as having	843	this). I recommend disabling thread support and using processes, as having
721	the windows process emulation enabled under unix roughly halves perl	844	the windows process emulation enabled under unix roughly halves perl
722	performance, even when not used.	845	performance, even when not used.
723		846
724	=item coroutine switching not signal safe	847	=item coro switching is not signal safe
725		848
726	You must not switch to another coroutine from within a signal handler	849	You must not switch to another coro from within a signal handler
727	(only relevant with %SIG - most event libraries provide safe signals).	850	(only relevant with %SIG - most event libraries provide safe signals).
728		851
729	That means you I<MUST NOT> call any function that might "block" the	852	That means you I<MUST NOT> call any function that might "block" the
730	current coroutine - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or	853	current coro - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or
731	anything that calls those. Everything else, including calling C<ready>,	854	anything that calls those. Everything else, including calling C<ready>,
732	works.	855	works.
733		856
734	=back	857	=back
735		858
		859
		860	=head1 WINDOWS PROCESS EMULATION
		861
		862	A great many people seem to be confused about ithreads (for example, Chip
		863	Salzenberg called me unintelligent, incapable, stupid and gullible,
		864	while in the same mail making rather confused statements about perl
		865	ithreads (for example, that memory or files would be shared), showing his
		866	lack of understanding of this area - if it is hard to understand for Chip,
		867	it is probably not obvious to everybody).
		868
		869	What follows is an ultra-condensed version of my talk about threads in
		870	scripting languages given onthe perl workshop 2009:
		871
		872	The so-called "ithreads" were originally implemented for two reasons:
		873	first, to (badly) emulate unix processes on native win32 perls, and
		874	secondly, to replace the older, real thread model ("5.005-threads").
		875
		876	It does that by using threads instead of OS processes. The difference
		877	between processes and threads is that threads share memory (and other
		878	state, such as files) between threads within a single process, while
		879	processes do not share anything (at least not semantically). That
		880	means that modifications done by one thread are seen by others, while
		881	modifications by one process are not seen by other processes.
		882
		883	The "ithreads" work exactly like that: when creating a new ithreads
		884	process, all state is copied (memory is copied physically, files and code
		885	is copied logically). Afterwards, it isolates all modifications. On UNIX,
		886	the same behaviour can be achieved by using operating system processes,
		887	except that UNIX typically uses hardware built into the system to do this
		888	efficiently, while the windows process emulation emulates this hardware in
		889	software (rather efficiently, but of course it is still much slower than
		890	dedicated hardware).
		891
		892	As mentioned before, loading code, modifying code, modifying data
		893	structures and so on is only visible in the ithreads process doing the
		894	modification, not in other ithread processes within the same OS process.
		895
		896	This is why "ithreads" do not implement threads for perl at all, only
		897	processes. What makes it so bad is that on non-windows platforms, you can
		898	actually take advantage of custom hardware for this purpose (as evidenced
		899	by the forks module, which gives you the (i-) threads API, just much
		900	faster).
		901
		902	Sharing data is in the i-threads model is done by transfering data
		903	structures between threads using copying semantics, which is very slow -
		904	shared data simply does not exist. Benchmarks using i-threads which are
		905	communication-intensive show extremely bad behaviour with i-threads (in
		906	fact, so bad that Coro, which cannot take direct advantage of multiple
		907	CPUs, is often orders of magnitude faster because it shares data using
		908	real threads, refer to my talk for details).
		909
		910	As summary, i-threads use threads to implement processes, while
		911	the compatible forks module uses processes to emulate, uhm,
		912	processes. I-threads slow down every perl program when enabled, and
		913	outside of windows, serve no (or little) practical purpose, but
		914	disadvantages every single-threaded Perl program.
		915
		916	This is the reason that I try to avoid the name "ithreads", as it is
		917	misleading as it implies that it implements some kind of thread model for
		918	perl, and prefer the name "windows process emulation", which describes the
		919	actual use and behaviour of it much better.
736		920
737	=head1 SEE ALSO	921	=head1 SEE ALSO
738		922
739	Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.	923	Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
740		924

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Comparing Coro/Coro.pm (file contents):
Revision 1.244 by root, Sat Dec 13 22:08:13 2008 UTC vs.
Revision 1.268 by root, Thu Oct 1 23:16:27 2009 UTC