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

Comparing Coro/Coro.pm (file contents):
Revision 1.246 by root, Mon Dec 15 00:30:40 2008 UTC vs.
Revision 1.271 by root, Fri Oct 2 19:55:59 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 ();
70		75
71	use Guard ();	76	use Guard ();
72		77
73	use Coro::State;	78	use Coro::State;
74		79
75	use base qw(Coro::State Exporter);	80	use base qw(Coro::State Exporter);
76		81
77	our $idle; # idle handler	82	our $idle; # idle handler
78	our $main; # main coroutine	83	our $main; # main coro
79	our $current; # current coroutine	84	our $current; # current coro
80		85
81	our $VERSION = 5.13;	86	our $VERSION = 5.2;
82		87
83	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);	88	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub rouse_cb rouse_wait);
84	our %EXPORT_TAGS = (	89	our %EXPORT_TAGS = (
85	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	90	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
86	);	91	);
87	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));	92	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
88		93
…		…
90		95
91	=over 4	96	=over 4
92		97
93	=item $Coro::main	98	=item $Coro::main
94		99
95	This variable stores the coroutine object that represents the main	100	This variable stores the Coro object that represents the main
96	program. While you cna C<ready> it and do most other things you can do to	101	program. While you cna C<ready> it and do most other things you can do to
97	coroutines, it is mainly useful to compare again C<$Coro::current>, to see	102	coro, it is mainly useful to compare again C<$Coro::current>, to see
98	whether you are running in the main program or not.	103	whether you are running in the main program or not.
99		104
100	=cut	105	=cut
101		106
102	# $main is now being initialised by Coro::State	107	# $main is now being initialised by Coro::State
103		108
104	=item $Coro::current	109	=item $Coro::current
105		110
106	The coroutine object representing the current coroutine (the last	111	The Coro object representing the current coro (the last
107	coroutine that the Coro scheduler switched to). The initial value is	112	coro that the Coro scheduler switched to). The initial value is
108	C<$Coro::main> (of course).	113	C<$Coro::main> (of course).
109		114
110	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
111	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
112	not otherwise modify the variable itself.	117	not otherwise modify the variable itself.
113		118
114	=cut	119	=cut
115		120
116	sub current() { $current } # [DEPRECATED]	121	sub current() { $current } # [DEPRECATED]
…		…
119		124
120	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
121	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
122	pretty low-level functionality.	127	pretty low-level functionality.
123		128
124	This variable stores either a coroutine or a callback.	129	This variable stores a Coro object that is put into the ready queue when
		130	there are no other ready threads (without invoking any ready hooks).
125		131
126	If it is a callback, the it is called whenever the scheduler finds no	132	The default implementation dies with "FATAL: deadlock detected.", followed
127	ready coroutines to run. The default implementation prints "FATAL:	133	by a thread listing, because the program has no other way to continue.
128	deadlock detected" and exits, because the program has no other way to
129	continue.
130
131	If it is a coroutine object, then this object will be readied (without
132	invoking any ready hooks, however) when the scheduler finds no other ready
133	coroutines to run.
134		134
135	This hook is overwritten by modules such as C<Coro::EV> and	135	This hook is overwritten by modules such as C<Coro::EV> and
136	C<Coro::AnyEvent> to wait on an external event that hopefully wake up a	136	C<Coro::AnyEvent> to wait on an external event that hopefully wake up a
137	coroutine so the scheduler can run it.	137	coro so the scheduler can run it.
138		138
139	Note that the callback I<must not>, under any circumstances, block
140	the current coroutine. Normally, this is achieved by having an "idle
141	coroutine" that calls the event loop and then blocks again, and then
142	readying that coroutine in the idle handler, or by simply placing the idle
143	coroutine in this variable.
144
145	See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this	139	See L<Coro::EV> or L<Coro::AnyEvent> for examples of using this technique.
146	technique.
147		140
148	Please note that if your callback recursively invokes perl (e.g. for event
149	handlers), then it must be prepared to be called recursively itself.
150
151	=cut	141	=cut
152		142
153	$idle = sub {	143	$idle = new Coro sub {
154	require Carp;	144	require Coro::Debug;
155	Carp::croak ("FATAL: deadlock detected");	145	die "FATAL: deadlock detected.\n"
		146	. Coro::Debug::ps_listing ();
156	};	147	};
157		148
158	# this coroutine is necessary because a coroutine	149	# this coro is necessary because a coro
159	# cannot destroy itself.	150	# cannot destroy itself.
160	our @destroy;	151	our @destroy;
161	our $manager;	152	our $manager;
162		153
163	$manager = new Coro sub {	154	$manager = new Coro sub {
164	while () {	155	while () {
165	Coro::_cancel shift @destroy	156	Coro::State::cancel shift @destroy
166	while @destroy;	157	while @destroy;
167		158
168	&schedule;	159	&schedule;
169	}	160	}
170	};	161	};
171	$manager->{desc} = "[coro manager]";	162	$manager->{desc} = "[coro manager]";
172	$manager->prio (PRIO_MAX);	163	$manager->prio (PRIO_MAX);
173		164
174	=back	165	=back
175		166
176	=head1 SIMPLE COROUTINE CREATION	167	=head1 SIMPLE CORO CREATION
177		168
178	=over 4	169	=over 4
179		170
180	=item async { ... } [@args...]	171	=item async { ... } [@args...]
181		172
182	Create a new coroutine and return its coroutine object (usually	173	Create a new coro and return its Coro object (usually
183	unused). The coroutine will be put into the ready queue, so	174	unused). The coro will be put into the ready queue, so
184	it will start running automatically on the next scheduler run.	175	it will start running automatically on the next scheduler run.
185		176
186	The first argument is a codeblock/closure that should be executed in the	177	The first argument is a codeblock/closure that should be executed in the
187	coroutine. When it returns argument returns the coroutine is automatically	178	coro. When it returns argument returns the coro is automatically
188	terminated.	179	terminated.
189		180
190	The remaining arguments are passed as arguments to the closure.	181	The remaining arguments are passed as arguments to the closure.
191		182
192	See the C<Coro::State::new> constructor for info about the coroutine	183	See the C<Coro::State::new> constructor for info about the coro
193	environment in which coroutines are executed.	184	environment in which coro are executed.
194		185
195	Calling C<exit> in a coroutine will do the same as calling exit outside	186	Calling C<exit> in a coro will do the same as calling exit outside
196	the coroutine. Likewise, when the coroutine dies, the program will exit,	187	the coro. Likewise, when the coro dies, the program will exit,
197	just as it would in the main program.	188	just as it would in the main program.
198		189
199	If you do not want that, you can provide a default C<die> handler, or	190	If you do not want that, you can provide a default C<die> handler, or
200	simply avoid dieing (by use of C<eval>).	191	simply avoid dieing (by use of C<eval>).
201		192
202	Example: Create a new coroutine that just prints its arguments.	193	Example: Create a new coro that just prints its arguments.
203		194
204	async {	195	async {
205	print "@_\n";	196	print "@_\n";
206	} 1,2,3,4;	197	} 1,2,3,4;
207		198
208	=cut
209
210	sub async(&@) {
211	my $coro = new Coro @_;
212	$coro->ready;
213	$coro
214	}
215
216	=item async_pool { ... } [@args...]	199	=item async_pool { ... } [@args...]
217		200
218	Similar to C<async>, but uses a coroutine pool, so you should not call	201	Similar to C<async>, but uses a coro pool, so you should not call
219	terminate or join on it (although you are allowed to), and you get a	202	terminate or join on it (although you are allowed to), and you get a
220	coroutine that might have executed other code already (which can be good	203	coro that might have executed other code already (which can be good
221	or bad :).	204	or bad :).
222		205
223	On the plus side, this function is about twice as fast as creating (and	206	On the plus side, this function is about twice as fast as creating (and
224	destroying) a completely new coroutine, so if you need a lot of generic	207	destroying) a completely new coro, so if you need a lot of generic
225	coroutines in quick successsion, use C<async_pool>, not C<async>.	208	coros in quick successsion, use C<async_pool>, not C<async>.
226		209
227	The code block is executed in an C<eval> context and a warning will be	210	The code block is executed in an C<eval> context and a warning will be
228	issued in case of an exception instead of terminating the program, as	211	issued in case of an exception instead of terminating the program, as
229	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>	212	C<async> does. As the coro is being reused, stuff like C<on_destroy>
230	will not work in the expected way, unless you call terminate or cancel,	213	will not work in the expected way, unless you call terminate or cancel,
231	which somehow defeats the purpose of pooling (but is fine in the	214	which somehow defeats the purpose of pooling (but is fine in the
232	exceptional case).	215	exceptional case).
233		216
234	The priority will be reset to C<0> after each run, tracing will be	217	The priority will be reset to C<0> after each run, tracing will be
235	disabled, the description will be reset and the default output filehandle	218	disabled, the description will be reset and the default output filehandle
236	gets restored, so you can change all these. Otherwise the coroutine will	219	gets restored, so you can change all these. Otherwise the coro will
237	be re-used "as-is": most notably if you change other per-coroutine global	220	be re-used "as-is": most notably if you change other per-coro global
238	stuff such as C<$/> you I<must needs> revert that change, which is most	221	stuff such as C<$/> you I<must needs> revert that change, which is most
239	simply done by using local as in: C<< local $/ >>.	222	simply done by using local as in: C<< local $/ >>.
240		223
241	The idle pool size is limited to C<8> idle coroutines (this can be	224	The idle pool size is limited to C<8> idle coros (this can be
242	adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle	225	adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle
243	coros as required.	226	coros as required.
244		227
245	If you are concerned about pooled coroutines growing a lot because a	228	If you are concerned about pooled coros growing a lot because a
246	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool	229	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
247	{ terminate }> once per second or so to slowly replenish the pool. In	230	{ terminate }> once per second or so to slowly replenish the pool. In
248	addition to that, when the stacks used by a handler grows larger than 32kb	231	addition to that, when the stacks used by a handler grows larger than 32kb
249	(adjustable via $Coro::POOL_RSS) it will also be destroyed.	232	(adjustable via $Coro::POOL_RSS) it will also be destroyed.
250		233
…		…
267	=back	250	=back
268		251
269	=head1 STATIC METHODS	252	=head1 STATIC METHODS
270		253
271	Static methods are actually functions that implicitly operate on the	254	Static methods are actually functions that implicitly operate on the
272	current coroutine.	255	current coro.
273		256
274	=over 4	257	=over 4
275		258
276	=item schedule	259	=item schedule
277		260
278	Calls the scheduler. The scheduler will find the next coroutine that is	261	Calls the scheduler. The scheduler will find the next coro that is
279	to be run from the ready queue and switches to it. The next coroutine	262	to be run from the ready queue and switches to it. The next coro
280	to be run is simply the one with the highest priority that is longest	263	to be run is simply the one with the highest priority that is longest
281	in its ready queue. If there is no coroutine ready, it will clal the	264	in its ready queue. If there is no coro ready, it will call the
282	C<$Coro::idle> hook.	265	C<$Coro::idle> hook.
283		266
284	Please note that the current coroutine will I<not> be put into the ready	267	Please note that the current coro will I<not> be put into the ready
285	queue, so calling this function usually means you will never be called	268	queue, so calling this function usually means you will never be called
286	again unless something else (e.g. an event handler) calls C<< ->ready >>,	269	again unless something else (e.g. an event handler) calls C<< ->ready >>,
287	thus waking you up.	270	thus waking you up.
288		271
289	This makes C<schedule> I<the> generic method to use to block the current	272	This makes C<schedule> I<the> generic method to use to block the current
290	coroutine and wait for events: first you remember the current coroutine in	273	coro and wait for events: first you remember the current coro in
291	a variable, then arrange for some callback of yours to call C<< ->ready	274	a variable, then arrange for some callback of yours to call C<< ->ready
292	>> on that once some event happens, and last you call C<schedule> to put	275	>> on that once some event happens, and last you call C<schedule> to put
293	yourself to sleep. Note that a lot of things can wake your coroutine up,	276	yourself to sleep. Note that a lot of things can wake your coro up,
294	so you need to check whether the event indeed happened, e.g. by storing the	277	so you need to check whether the event indeed happened, e.g. by storing the
295	status in a variable.	278	status in a variable.
296		279
297	See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks.	280	See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks.
298		281
299	=item cede	282	=item cede
300		283
301	"Cede" to other coroutines. This function puts the current coroutine into	284	"Cede" to other coros. This function puts the current coro into
302	the ready queue and calls C<schedule>, which has the effect of giving	285	the ready queue and calls C<schedule>, which has the effect of giving
303	up the current "timeslice" to other coroutines of the same or higher	286	up the current "timeslice" to other coros of the same or higher
304	priority. Once your coroutine gets its turn again it will automatically be	287	priority. Once your coro gets its turn again it will automatically be
305	resumed.	288	resumed.
306		289
307	This function is often called C<yield> in other languages.	290	This function is often called C<yield> in other languages.
308		291
309	=item Coro::cede_notself	292	=item Coro::cede_notself
310		293
311	Works like cede, but is not exported by default and will cede to I<any>	294	Works like cede, but is not exported by default and will cede to I<any>
312	coroutine, regardless of priority. This is useful sometimes to ensure	295	coro, regardless of priority. This is useful sometimes to ensure
313	progress is made.	296	progress is made.
314		297
315	=item terminate [arg...]	298	=item terminate [arg...]
316		299
317	Terminates the current coroutine with the given status values (see L<cancel>).	300	Terminates the current coro with the given status values (see L<cancel>).
		301
		302	=item Coro::on_enter BLOCK, Coro::on_leave BLOCK
		303
		304	These function install enter and leave winders in the current scope. The
		305	enter block will be executed when on_enter is called and whenever the
		306	current coro is re-entered by the scheduler, while the leave block is
		307	executed whenever the current coro is blocked by the scheduler, and
		308	also when the containing scope is exited (by whatever means, be it exit,
		309	die, last etc.).
		310
		311	I<Neither invoking the scheduler, nor exceptions, are allowed within those
		312	BLOCKs>. That means: do not even think about calling C<die> without an
		313	eval, and do not even think of entering the scheduler in any way.
		314
		315	Since both BLOCKs are tied to the current scope, they will automatically
		316	be removed when the current scope exits.
		317
		318	These functions implement the same concept as C<dynamic-wind> in scheme
		319	does, and are useful when you want to localise some resource to a specific
		320	coro.
		321
		322	They slow down thread switching considerably for coros that use them
		323	(about 40% for a BLOCK with a single assignment, so thread switching is
		324	still reasonably fast if the handlers are fast).
		325
		326	These functions are best understood by an example: The following function
		327	will change the current timezone to "Antarctica/South_Pole", which
		328	requires a call to C<tzset>, but by using C<on_enter> and C<on_leave>,
		329	which remember/change the current timezone and restore the previous
		330	value, respectively, the timezone is only changed for the coro that
		331	installed those handlers.
		332
		333	use POSIX qw(tzset);
		334
		335	async {
		336	my $old_tz; # store outside TZ value here
		337
		338	Coro::on_enter {
		339	$old_tz = $ENV{TZ}; # remember the old value
		340
		341	$ENV{TZ} = "Antarctica/South_Pole";
		342	tzset; # enable new value
		343	};
		344
		345	Coro::on_leave {
		346	$ENV{TZ} = $old_tz;
		347	tzset; # restore old value
		348	};
		349
		350	# at this place, the timezone is Antarctica/South_Pole,
		351	# without disturbing the TZ of any other coro.
		352	};
		353
		354	This can be used to localise about any resource (locale, uid, current
		355	working directory etc.) to a block, despite the existance of other
		356	coros.
		357
		358	Another interesting example implements time-sliced multitasking using
		359	interval timers (this could obviously be optimised, but does the job):
		360
		361	# "timeslice" the given block
		362	sub timeslice(&) {
		363	use Time::HiRes ();
		364
		365	Coro::on_enter {
		366	# on entering the thread, we set an VTALRM handler to cede
		367	$SIG{VTALRM} = sub { cede };
		368	# and then start the interval timer
		369	Time::HiRes::setitimer &Time::HiRes::ITIMER_VIRTUAL, 0.01, 0.01;
		370	};
		371	Coro::on_leave {
		372	# on leaving the thread, we stop the interval timer again
		373	Time::HiRes::setitimer &Time::HiRes::ITIMER_VIRTUAL, 0, 0;
		374	};
		375
		376	&{+shift};
		377	}
		378
		379	# use like this:
		380	timeslice {
		381	# The following is an endless loop that would normally
		382	# monopolise the process. Since it runs in a timesliced
		383	# environment, it will regularly cede to other threads.
		384	while () { }
		385	};
		386
318		387
319	=item killall	388	=item killall
320		389
321	Kills/terminates/cancels all coroutines except the currently running	390	Kills/terminates/cancels all coros except the currently running one.
322	one. This can be useful after a fork, either in the child or the parent,
323	as usually only one of them should inherit the running coroutines.
324		391
325	Note that in the implementation, destructors run as normal, making this
326	function not so useful after a fork. Future versions of this function
327	might try to free resources without running any code.
328
329	Note that while this will try to free some of the main programs resources,	392	Note that while this will try to free some of the main interpreter
		393	resources if the calling coro isn't the main coro, but one
330	you cannot free all of them, so if a coroutine that is not the main	394	cannot free all of them, so if a coro that is not the main coro
331	program calls this function, there will be some one-time resource leak.	395	calls this function, there will be some one-time resource leak.
332		396
333	=cut	397	=cut
334		398
335	sub killall {	399	sub killall {
336	for (Coro::State::list) {	400	for (Coro::State::list) {
…		…
339	}	403	}
340	}	404	}
341		405
342	=back	406	=back
343		407
344	=head1 COROUTINE OBJECT METHODS	408	=head1 CORO OBJECT METHODS
345		409
346	These are the methods you can call on coroutine objects (or to create	410	These are the methods you can call on coro objects (or to create
347	them).	411	them).
348		412
349	=over 4	413	=over 4
350		414
351	=item new Coro \&sub [, @args...]	415	=item new Coro \&sub [, @args...]
352		416
353	Create a new coroutine and return it. When the sub returns, the coroutine	417	Create a new coro and return it. When the sub returns, the coro
354	automatically terminates as if C<terminate> with the returned values were	418	automatically terminates as if C<terminate> with the returned values were
355	called. To make the coroutine run you must first put it into the ready	419	called. To make the coro run you must first put it into the ready
356	queue by calling the ready method.	420	queue by calling the ready method.
357		421
358	See C<async> and C<Coro::State::new> for additional info about the	422	See C<async> and C<Coro::State::new> for additional info about the
359	coroutine environment.	423	coro environment.
360		424
361	=cut	425	=cut
362		426
363	sub _coro_run {	427	sub _coro_run {
364	terminate &{+shift};	428	terminate &{+shift};
365	}	429	}
366		430
367	=item $success = $coroutine->ready	431	=item $success = $coro->ready
368		432
369	Put the given coroutine into the end of its ready queue (there is one	433	Put the given coro into the end of its ready queue (there is one
370	queue for each priority) and return true. If the coroutine is already in	434	queue for each priority) and return true. If the coro is already in
371	the ready queue, do nothing and return false.	435	the ready queue, do nothing and return false.
372		436
373	This ensures that the scheduler will resume this coroutine automatically	437	This ensures that the scheduler will resume this coro automatically
374	once all the coroutines of higher priority and all coroutines of the same	438	once all the coro of higher priority and all coro of the same
375	priority that were put into the ready queue earlier have been resumed.	439	priority that were put into the ready queue earlier have been resumed.
376		440
		441	=item $coro->suspend
		442
		443	Suspends the specified coro. A suspended coro works just like any other
		444	coro, except that the scheduler will not select a suspended coro for
		445	execution.
		446
		447	Suspending a coro can be useful when you want to keep the coro from
		448	running, but you don't want to destroy it, or when you want to temporarily
		449	freeze a coro (e.g. for debugging) to resume it later.
		450
		451	A scenario for the former would be to suspend all (other) coros after a
		452	fork and keep them alive, so their destructors aren't called, but new
		453	coros can be created.
		454
		455	=item $coro->resume
		456
		457	If the specified coro was suspended, it will be resumed. Note that when
		458	the coro was in the ready queue when it was suspended, it might have been
		459	unreadied by the scheduler, so an activation might have been lost.
		460
		461	To avoid this, it is best to put a suspended coro into the ready queue
		462	unconditionally, as every synchronisation mechanism must protect itself
		463	against spurious wakeups, and the one in the Coro family certainly do
		464	that.
		465
377	=item $is_ready = $coroutine->is_ready	466	=item $is_ready = $coro->is_ready
378		467
379	Return whether the coroutine is currently the ready queue or not,	468	Returns true iff the Coro object is in the ready queue. Unless the Coro
		469	object gets destroyed, it will eventually be scheduled by the scheduler.
380		470
		471	=item $is_running = $coro->is_running
		472
		473	Returns true iff the Coro object is currently running. Only one Coro object
		474	can ever be in the running state (but it currently is possible to have
		475	multiple running Coro::States).
		476
		477	=item $is_suspended = $coro->is_suspended
		478
		479	Returns true iff this Coro object has been suspended. Suspended Coros will
		480	not ever be scheduled.
		481
381	=item $coroutine->cancel (arg...)	482	=item $coro->cancel (arg...)
382		483
383	Terminates the given coroutine and makes it return the given arguments as	484	Terminates the given Coro and makes it return the given arguments as
384	status (default: the empty list). Never returns if the coroutine is the	485	status (default: the empty list). Never returns if the Coro is the
385	current coroutine.	486	current Coro.
386		487
387	=cut	488	=cut
388		489
389	sub cancel {	490	sub cancel {
390	my $self = shift;	491	my $self = shift;
391		492
392	if ($current == $self) {	493	if ($current == $self) {
393	terminate @_;	494	terminate @_;
394	} else {	495	} else {
395	$self->{_status} = [@_];	496	$self->{_status} = [@_];
396	$self->_cancel;	497	Coro::State::cancel $self;
397	}	498	}
398	}	499	}
399		500
400	=item $coroutine->schedule_to	501	=item $coro->schedule_to
401		502
402	Puts the current coroutine to sleep (like C<Coro::schedule>), but instead	503	Puts the current coro to sleep (like C<Coro::schedule>), but instead
403	of continuing with the next coro from the ready queue, always switch to	504	of continuing with the next coro from the ready queue, always switch to
404	the given coroutine object (regardless of priority etc.). The readyness	505	the given coro object (regardless of priority etc.). The readyness
405	state of that coroutine isn't changed.	506	state of that coro isn't changed.
406		507
407	This is an advanced method for special cases - I'd love to hear about any	508	This is an advanced method for special cases - I'd love to hear about any
408	uses for this one.	509	uses for this one.
409		510
410	=item $coroutine->cede_to	511	=item $coro->cede_to
411		512
412	Like C<schedule_to>, but puts the current coroutine into the ready	513	Like C<schedule_to>, but puts the current coro into the ready
413	queue. This has the effect of temporarily switching to the given	514	queue. This has the effect of temporarily switching to the given
414	coroutine, and continuing some time later.	515	coro, and continuing some time later.
415		516
416	This is an advanced method for special cases - I'd love to hear about any	517	This is an advanced method for special cases - I'd love to hear about any
417	uses for this one.	518	uses for this one.
418		519
419	=item $coroutine->throw ([$scalar])	520	=item $coro->throw ([$scalar])
420		521
421	If C<$throw> is specified and defined, it will be thrown as an exception	522	If C<$throw> is specified and defined, it will be thrown as an exception
422	inside the coroutine at the next convenient point in time. Otherwise	523	inside the coro at the next convenient point in time. Otherwise
423	clears the exception object.	524	clears the exception object.
424		525
425	Coro will check for the exception each time a schedule-like-function	526	Coro will check for the exception each time a schedule-like-function
426	returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down	527	returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down
427	>>, C<< Coro::Handle->readable >> and so on. Most of these functions	528	>>, C<< Coro::Handle->readable >> and so on. Most of these functions
…		…
429		530
430	The exception object will be thrown "as is" with the specified scalar in	531	The exception object will be thrown "as is" with the specified scalar in
431	C<$@>, i.e. if it is a string, no line number or newline will be appended	532	C<$@>, i.e. if it is a string, no line number or newline will be appended
432	(unlike with C<die>).	533	(unlike with C<die>).
433		534
434	This can be used as a softer means than C<cancel> to ask a coroutine to	535	This can be used as a softer means than C<cancel> to ask a coro to
435	end itself, although there is no guarantee that the exception will lead to	536	end itself, although there is no guarantee that the exception will lead to
436	termination, and if the exception isn't caught it might well end the whole	537	termination, and if the exception isn't caught it might well end the whole
437	program.	538	program.
438		539
439	You might also think of C<throw> as being the moral equivalent of	540	You might also think of C<throw> as being the moral equivalent of
440	C<kill>ing a coroutine with a signal (in this case, a scalar).	541	C<kill>ing a coro with a signal (in this case, a scalar).
441		542
442	=item $coroutine->join	543	=item $coro->join
443		544
444	Wait until the coroutine terminates and return any values given to the	545	Wait until the coro terminates and return any values given to the
445	C<terminate> or C<cancel> functions. C<join> can be called concurrently	546	C<terminate> or C<cancel> functions. C<join> can be called concurrently
446	from multiple coroutines, and all will be resumed and given the status	547	from multiple coro, and all will be resumed and given the status
447	return once the C<$coroutine> terminates.	548	return once the C<$coro> terminates.
448		549
449	=cut	550	=cut
450		551
451	sub join {	552	sub join {
452	my $self = shift;	553	my $self = shift;
…		…
463	}	564	}
464		565
465	wantarray ? @{$self->{_status}} : $self->{_status}[0];	566	wantarray ? @{$self->{_status}} : $self->{_status}[0];
466	}	567	}
467		568
468	=item $coroutine->on_destroy (\&cb)	569	=item $coro->on_destroy (\&cb)
469		570
470	Registers a callback that is called when this coroutine gets destroyed,	571	Registers a callback that is called when this coro gets destroyed,
471	but before it is joined. The callback gets passed the terminate arguments,	572	but before it is joined. The callback gets passed the terminate arguments,
472	if any, and I<must not> die, under any circumstances.	573	if any, and I<must not> die, under any circumstances.
473		574
474	=cut	575	=cut
475		576
…		…
477	my ($self, $cb) = @_;	578	my ($self, $cb) = @_;
478		579
479	push @{ $self->{_on_destroy} }, $cb;	580	push @{ $self->{_on_destroy} }, $cb;
480	}	581	}
481		582
482	=item $oldprio = $coroutine->prio ($newprio)	583	=item $oldprio = $coro->prio ($newprio)
483		584
484	Sets (or gets, if the argument is missing) the priority of the	585	Sets (or gets, if the argument is missing) the priority of the
485	coroutine. Higher priority coroutines get run before lower priority	586	coro. Higher priority coro get run before lower priority
486	coroutines. Priorities are small signed integers (currently -4 .. +3),	587	coro. Priorities are small signed integers (currently -4 .. +3),
487	that you can refer to using PRIO_xxx constants (use the import tag :prio	588	that you can refer to using PRIO_xxx constants (use the import tag :prio
488	to get then):	589	to get then):
489		590
490	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN	591	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
491	3 > 1 > 0 > -1 > -3 > -4	592	3 > 1 > 0 > -1 > -3 > -4
492		593
493	# set priority to HIGH	594	# set priority to HIGH
494	current->prio(PRIO_HIGH);	595	current->prio (PRIO_HIGH);
495		596
496	The idle coroutine ($Coro::idle) always has a lower priority than any	597	The idle coro ($Coro::idle) always has a lower priority than any
497	existing coroutine.	598	existing coro.
498		599
499	Changing the priority of the current coroutine will take effect immediately,	600	Changing the priority of the current coro will take effect immediately,
500	but changing the priority of coroutines in the ready queue (but not	601	but changing the priority of coro in the ready queue (but not
501	running) will only take effect after the next schedule (of that	602	running) will only take effect after the next schedule (of that
502	coroutine). This is a bug that will be fixed in some future version.	603	coro). This is a bug that will be fixed in some future version.
503		604
504	=item $newprio = $coroutine->nice ($change)	605	=item $newprio = $coro->nice ($change)
505		606
506	Similar to C<prio>, but subtract the given value from the priority (i.e.	607	Similar to C<prio>, but subtract the given value from the priority (i.e.
507	higher values mean lower priority, just as in unix).	608	higher values mean lower priority, just as in unix).
508		609
509	=item $olddesc = $coroutine->desc ($newdesc)	610	=item $olddesc = $coro->desc ($newdesc)
510		611
511	Sets (or gets in case the argument is missing) the description for this	612	Sets (or gets in case the argument is missing) the description for this
512	coroutine. This is just a free-form string you can associate with a	613	coro. This is just a free-form string you can associate with a
513	coroutine.	614	coro.
514		615
515	This method simply sets the C<< $coroutine->{desc} >> member to the given	616	This method simply sets the C<< $coro->{desc} >> member to the given
516	string. You can modify this member directly if you wish.	617	string. You can modify this member directly if you wish.
517		618
518	=cut	619	=cut
519		620
520	sub desc {	621	sub desc {
…		…
534		635
535	=over 4	636	=over 4
536		637
537	=item Coro::nready	638	=item Coro::nready
538		639
539	Returns the number of coroutines that are currently in the ready state,	640	Returns the number of coro that are currently in the ready state,
540	i.e. that can be switched to by calling C<schedule> directory or	641	i.e. that can be switched to by calling C<schedule> directory or
541	indirectly. The value C<0> means that the only runnable coroutine is the	642	indirectly. The value C<0> means that the only runnable coro is the
542	currently running one, so C<cede> would have no effect, and C<schedule>	643	currently running one, so C<cede> would have no effect, and C<schedule>
543	would cause a deadlock unless there is an idle handler that wakes up some	644	would cause a deadlock unless there is an idle handler that wakes up some
544	coroutines.	645	coro.
545		646
546	=item my $guard = Coro::guard { ... }	647	=item my $guard = Coro::guard { ... }
547		648
548	This function still exists, but is deprecated. Please use the	649	This function still exists, but is deprecated. Please use the
549	C<Guard::guard> function instead.	650	C<Guard::guard> function instead.
…		…
556		657
557	This utility function takes a BLOCK or code reference and "unblocks" it,	658	This utility function takes a BLOCK or code reference and "unblocks" it,
558	returning a new coderef. Unblocking means that calling the new coderef	659	returning a new coderef. Unblocking means that calling the new coderef
559	will return immediately without blocking, returning nothing, while the	660	will return immediately without blocking, returning nothing, while the
560	original code ref will be called (with parameters) from within another	661	original code ref will be called (with parameters) from within another
561	coroutine.	662	coro.
562		663
563	The reason this function exists is that many event libraries (such as the	664	The reason this function exists is that many event libraries (such as the
564	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form	665	venerable L<Event\|Event> module) are not thread-safe (a weaker form
565	of reentrancy). This means you must not block within event callbacks,	666	of reentrancy). This means you must not block within event callbacks,
566	otherwise you might suffer from crashes or worse. The only event library	667	otherwise you might suffer from crashes or worse. The only event library
567	currently known that is safe to use without C<unblock_sub> is L<EV>.	668	currently known that is safe to use without C<unblock_sub> is L<EV>.
568		669
569	This function allows your callbacks to block by executing them in another	670	This function allows your callbacks to block by executing them in another
570	coroutine where it is safe to block. One example where blocking is handy	671	coro where it is safe to block. One example where blocking is handy
571	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to	672	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
572	disk, for example.	673	disk, for example.
573		674
574	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when	675	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
575	creating event callbacks that want to block.	676	creating event callbacks that want to block.
576		677
577	If your handler does not plan to block (e.g. simply sends a message to	678	If your handler does not plan to block (e.g. simply sends a message to
578	another coroutine, or puts some other coroutine into the ready queue),	679	another coro, or puts some other coro into the ready queue), there is
579	there is no reason to use C<unblock_sub>.	680	no reason to use C<unblock_sub>.
580		681
581	Note that you also need to use C<unblock_sub> for any other callbacks that	682	Note that you also need to use C<unblock_sub> for any other callbacks that
582	are indirectly executed by any C-based event loop. For example, when you	683	are indirectly executed by any C-based event loop. For example, when you
583	use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it	684	use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it
584	provides callbacks that are the result of some event callback, then you	685	provides callbacks that are the result of some event callback, then you
…		…
614	unshift @unblock_queue, [$cb, @_];	715	unshift @unblock_queue, [$cb, @_];
615	$unblock_scheduler->ready;	716	$unblock_scheduler->ready;
616	}	717	}
617	}	718	}
618		719
619	=item $cb = Coro::rouse_cb	720	=item $cb = rouse_cb
620		721
621	Create and return a "rouse callback". That's a code reference that,	722	Create and return a "rouse callback". That's a code reference that,
622	when called, will remember a copy of its arguments and notify the owner	723	when called, will remember a copy of its arguments and notify the owner
623	coroutine of the callback.	724	coro of the callback.
624		725
625	See the next function.	726	See the next function.
626		727
627	=item @args = Coro::rouse_wait [$cb]	728	=item @args = rouse_wait [$cb]
628		729
629	Wait for the specified rouse callback (or the last one that was created in	730	Wait for the specified rouse callback (or the last one that was created in
630	this coroutine).	731	this coro).
631		732
632	As soon as the callback is invoked (or when the callback was invoked	733	As soon as the callback is invoked (or when the callback was invoked
633	before C<rouse_wait>), it will return the arguments originally passed to	734	before C<rouse_wait>), it will return the arguments originally passed to
634	the rouse callback.	735	the rouse callback. In scalar context, that means you get the I<last>
		736	argument, just as if C<rouse_wait> had a C<return ($a1, $a2, $a3...)>
		737	statement at the end.
635		738
636	See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example.	739	See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example.
637		740
638	=back	741	=back
639		742
…		…
641		744
642	1;	745	1;
643		746
644	=head1 HOW TO WAIT FOR A CALLBACK	747	=head1 HOW TO WAIT FOR A CALLBACK
645		748
646	It is very common for a coroutine to wait for some callback to be	749	It is very common for a coro to wait for some callback to be
647	called. This occurs naturally when you use coroutines in an otherwise	750	called. This occurs naturally when you use coro in an otherwise
648	event-based program, or when you use event-based libraries.	751	event-based program, or when you use event-based libraries.
649		752
650	These typically register a callback for some event, and call that callback	753	These typically register a callback for some event, and call that callback
651	when the event occured. In a coroutine, however, you typically want to	754	when the event occured. In a coro, however, you typically want to
652	just wait for the event, simplyifying things.	755	just wait for the event, simplyifying things.
653		756
654	For example C<< AnyEvent->child >> registers a callback to be called when	757	For example C<< AnyEvent->child >> registers a callback to be called when
655	a specific child has exited:	758	a specific child has exited:
656		759
657	my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... });	760	my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... });
658		761
659	But from withina coroutine, you often just want to write this:	762	But from within a coro, you often just want to write this:
660		763
661	my $status = wait_for_child $pid;	764	my $status = wait_for_child $pid;
662		765
663	Coro offers two functions specifically designed to make this easy,	766	Coro offers two functions specifically designed to make this easy,
664	C<Coro::rouse_cb> and C<Coro::rouse_wait>.	767	C<Coro::rouse_cb> and C<Coro::rouse_wait>.
665		768
666	The first function, C<rouse_cb>, generates and returns a callback that,	769	The first function, C<rouse_cb>, generates and returns a callback that,
667	when invoked, will save its arguments and notify the coroutine that	770	when invoked, will save its arguments and notify the coro that
668	created the callback.	771	created the callback.
669		772
670	The second function, C<rouse_wait>, waits for the callback to be called	773	The second function, C<rouse_wait>, waits for the callback to be called
671	(by calling C<schedule> to go to sleep) and returns the arguments	774	(by calling C<schedule> to go to sleep) and returns the arguments
672	originally passed to the callback.	775	originally passed to the callback.
…		…
687	you can roll your own, using C<schedule>:	790	you can roll your own, using C<schedule>:
688		791
689	sub wait_for_child($) {	792	sub wait_for_child($) {
690	my ($pid) = @_;	793	my ($pid) = @_;
691		794
692	# store the current coroutine in $current,	795	# store the current coro in $current,
693	# and provide result variables for the closure passed to ->child	796	# and provide result variables for the closure passed to ->child
694	my $current = $Coro::current;	797	my $current = $Coro::current;
695	my ($done, $rstatus);	798	my ($done, $rstatus);
696		799
697	# pass a closure to ->child	800	# pass a closure to ->child
…		…
713		816
714	=item fork with pthread backend	817	=item fork with pthread backend
715		818
716	When Coro is compiled using the pthread backend (which isn't recommended	819	When Coro is compiled using the pthread backend (which isn't recommended
717	but required on many BSDs as their libcs are completely broken), then	820	but required on many BSDs as their libcs are completely broken), then
718	coroutines will not survive a fork. There is no known workaround except to	821	coro will not survive a fork. There is no known workaround except to
719	fix your libc and use a saner backend.	822	fix your libc and use a saner backend.
720		823
721	=item perl process emulation ("threads")	824	=item perl process emulation ("threads")
722		825
723	This module is not perl-pseudo-thread-safe. You should only ever use this	826	This module is not perl-pseudo-thread-safe. You should only ever use this
…		…
725	future to allow per-thread schedulers, but Coro::State does not yet allow	828	future to allow per-thread schedulers, but Coro::State does not yet allow
726	this). I recommend disabling thread support and using processes, as having	829	this). I recommend disabling thread support and using processes, as having
727	the windows process emulation enabled under unix roughly halves perl	830	the windows process emulation enabled under unix roughly halves perl
728	performance, even when not used.	831	performance, even when not used.
729		832
730	=item coroutine switching not signal safe	833	=item coro switching is not signal safe
731		834
732	You must not switch to another coroutine from within a signal handler	835	You must not switch to another coro from within a signal handler
733	(only relevant with %SIG - most event libraries provide safe signals).	836	(only relevant with %SIG - most event libraries provide safe signals).
734		837
735	That means you I<MUST NOT> call any function that might "block" the	838	That means you I<MUST NOT> call any function that might "block" the
736	current coroutine - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or	839	current coro - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or
737	anything that calls those. Everything else, including calling C<ready>,	840	anything that calls those. Everything else, including calling C<ready>,
738	works.	841	works.
739		842
740	=back	843	=back
741		844
		845
		846	=head1 WINDOWS PROCESS EMULATION
		847
		848	A great many people seem to be confused about ithreads (for example, Chip
		849	Salzenberg called me unintelligent, incapable, stupid and gullible,
		850	while in the same mail making rather confused statements about perl
		851	ithreads (for example, that memory or files would be shared), showing his
		852	lack of understanding of this area - if it is hard to understand for Chip,
		853	it is probably not obvious to everybody).
		854
		855	What follows is an ultra-condensed version of my talk about threads in
		856	scripting languages given onthe perl workshop 2009:
		857
		858	The so-called "ithreads" were originally implemented for two reasons:
		859	first, to (badly) emulate unix processes on native win32 perls, and
		860	secondly, to replace the older, real thread model ("5.005-threads").
		861
		862	It does that by using threads instead of OS processes. The difference
		863	between processes and threads is that threads share memory (and other
		864	state, such as files) between threads within a single process, while
		865	processes do not share anything (at least not semantically). That
		866	means that modifications done by one thread are seen by others, while
		867	modifications by one process are not seen by other processes.
		868
		869	The "ithreads" work exactly like that: when creating a new ithreads
		870	process, all state is copied (memory is copied physically, files and code
		871	is copied logically). Afterwards, it isolates all modifications. On UNIX,
		872	the same behaviour can be achieved by using operating system processes,
		873	except that UNIX typically uses hardware built into the system to do this
		874	efficiently, while the windows process emulation emulates this hardware in
		875	software (rather efficiently, but of course it is still much slower than
		876	dedicated hardware).
		877
		878	As mentioned before, loading code, modifying code, modifying data
		879	structures and so on is only visible in the ithreads process doing the
		880	modification, not in other ithread processes within the same OS process.
		881
		882	This is why "ithreads" do not implement threads for perl at all, only
		883	processes. What makes it so bad is that on non-windows platforms, you can
		884	actually take advantage of custom hardware for this purpose (as evidenced
		885	by the forks module, which gives you the (i-) threads API, just much
		886	faster).
		887
		888	Sharing data is in the i-threads model is done by transfering data
		889	structures between threads using copying semantics, which is very slow -
		890	shared data simply does not exist. Benchmarks using i-threads which are
		891	communication-intensive show extremely bad behaviour with i-threads (in
		892	fact, so bad that Coro, which cannot take direct advantage of multiple
		893	CPUs, is often orders of magnitude faster because it shares data using
		894	real threads, refer to my talk for details).
		895
		896	As summary, i-threads use threads to implement processes, while
		897	the compatible forks module uses processes to emulate, uhm,
		898	processes. I-threads slow down every perl program when enabled, and
		899	outside of windows, serve no (or little) practical purpose, but
		900	disadvantages every single-threaded Perl program.
		901
		902	This is the reason that I try to avoid the name "ithreads", as it is
		903	misleading as it implies that it implements some kind of thread model for
		904	perl, and prefer the name "windows process emulation", which describes the
		905	actual use and behaviour of it much better.
742		906
743	=head1 SEE ALSO	907	=head1 SEE ALSO
744		908
745	Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.	909	Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
746		910

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Comparing Coro/Coro.pm (file contents): Revision 1.246 by root, Mon Dec 15 00:30:40 2008 UTC vs. Revision 1.271 by root, Fri Oct 2 19:55:59 2009 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.246 by root, Mon Dec 15 00:30:40 2008 UTC vs.
Revision 1.271 by root, Fri Oct 2 19:55:59 2009 UTC