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

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Revision 1.180 by root, Fri Apr 25 04:28:50 2008 UTC vs.
Revision 1.264 by root, Thu Aug 13 02:35:41 2009 UTC

…		…
1	=head1 NAME	1	=head1 NAME
2		2
3	Coro - coroutine process abstraction	3	Coro - the only real threads in perl
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use Coro;	7	use Coro;
8		8
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	my $lock = new Coro::Semaphore;	22	my $lock = new Coro::Semaphore;
22	my $locked;	23	my $locked;
23		24
24	$lock->down;	25	$lock->down;
25	$locked = 1;	26	$locked = 1;
26	$lock->up;	27	$lock->up;
27		28
28	=head1 DESCRIPTION	29	=head1 DESCRIPTION
29		30
30	This module collection manages coroutines. Coroutines are similar	31	For a tutorial-style introduction, please read the L<Coro::Intro>
31	to threads but don't run in parallel at the same time even on SMP	32	manpage. This manpage mainly contains reference information.
32	machines. The specific flavor of coroutine used in this module also
33	guarantees you that it will not switch between coroutines unless
34	necessary, at easily-identified points in your program, so locking and
35	parallel access are rarely an issue, making coroutine programming much
36	safer than threads programming.
37		33
38	(Perl, however, does not natively support real threads but instead does a	34	This module collection manages continuations in general, most often in
39	very slow and memory-intensive emulation of processes using threads. This	35	the form of cooperative threads (also called coros, or simply "coro"
40	is a performance win on Windows machines, and a loss everywhere else).	36	in the documentation). They are similar to kernel threads but don't (in
		37	general) run in parallel at the same time even on SMP machines. The
		38	specific flavor of thread offered by this module also guarantees you that
		39	it will not switch between threads unless necessary, at easily-identified
		40	points in your program, so locking and parallel access are rarely an
		41	issue, making thread programming much safer and easier than using other
		42	thread models.
41		43
		44	Unlike the so-called "Perl threads" (which are not actually real threads
		45	but only the windows process emulation ported to unix, and as such act
		46	as processes), Coro provides a full shared address space, which makes
		47	communication between threads very easy. And Coro's threads are fast,
		48	too: disabling the Windows process emulation code in your perl and using
		49	Coro can easily result in a two to four times speed increase for your
		50	programs. A parallel matrix multiplication benchmark runs over 300 times
		51	faster on a single core than perl's pseudo-threads on a quad core using
		52	all four cores.
		53
		54	Coro achieves that by supporting multiple running interpreters that share
		55	data, which is especially useful to code pseudo-parallel processes and
		56	for event-based programming, such as multiple HTTP-GET requests running
		57	concurrently. See L<Coro::AnyEvent> to learn more on how to integrate Coro
		58	into an event-based environment.
		59
42	In this module, coroutines are defined as "callchain + lexical variables +	60	In this module, a thread is defined as "callchain + lexical variables +
43	@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,	61	some package variables + C stack), that is, a thread has its own callchain,
44	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
45	variables (see L<Coro::State> for more configuration).	63	variables (see L<Coro::State> for more configuration and background info).
		64
		65	See also the C<SEE ALSO> section at the end of this document - the Coro
		66	module family is quite large.
46		67
47	=cut	68	=cut
48		69
49	package Coro;	70	package Coro;
50		71
51	use strict;	72	use strict qw(vars subs);
52	no warnings "uninitialized";	73	no warnings "uninitialized";
53		74
		75	use Guard ();
		76
54	use Coro::State;	77	use Coro::State;
55		78
56	use base qw(Coro::State Exporter);	79	use base qw(Coro::State Exporter);
57		80
58	our $idle; # idle handler	81	our $idle; # idle handler
59	our $main; # main coroutine	82	our $main; # main coro
60	our $current; # current coroutine	83	our $current; # current coro
61		84
62	our $VERSION = 4.6;	85	our $VERSION = 5.162;
63		86
64	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);	87	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
65	our %EXPORT_TAGS = (	88	our %EXPORT_TAGS = (
66	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	89	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
67	);	90	);
68	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));	91	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
69		92
		93	=head1 GLOBAL VARIABLES
		94
70	=over 4	95	=over 4
71		96
72	=item $main	97	=item $Coro::main
73		98
74	This coroutine represents the main program.	99	This variable stores the Coro object that represents the main
		100	program. While you cna C<ready> it and do most other things you can do to
		101	coro, it is mainly useful to compare again C<$Coro::current>, to see
		102	whether you are running in the main program or not.
75		103
76	=cut	104	=cut
77		105
78	$main = new Coro;	106	# $main is now being initialised by Coro::State
79		107
80	=item $current (or as function: current)	108	=item $Coro::current
81		109
82	The current coroutine (the last coroutine switched to). The initial value	110	The Coro object representing the current coro (the last
		111	coro that the Coro scheduler switched to). The initial value is
83	is C<$main> (of course).	112	C<$Coro::main> (of course).
84		113
85	This variable is B<strictly> I<read-only>. It is provided for performance	114	This variable is B<strictly> I<read-only>. You can take copies of the
86	reasons. If performance is not essential you are encouraged to use the	115	value stored in it and use it as any other Coro object, but you must
87	C<Coro::current> function instead.	116	not otherwise modify the variable itself.
88		117
89	=cut	118	=cut
90		119
91	$main->{desc} = "[main::]";
92
93	# maybe some other module used Coro::Specific before...
94	$main->{_specific} = $current->{_specific}
95	if $current;
96
97	_set_current $main;
98
99	sub current() { $current }	120	sub current() { $current } # [DEPRECATED]
100		121
101	=item $idle	122	=item $Coro::idle
102		123
		124	This variable is mainly useful to integrate Coro into event loops. It is
		125	usually better to rely on L<Coro::AnyEvent> or L<Coro::EV>, as this is
		126	pretty low-level functionality.
		127
		128	This variable stores either a Coro object or a callback.
		129
103	A callback that is called whenever the scheduler finds no ready coroutines	130	If it is a callback, the it is called whenever the scheduler finds no
104	to run. The default implementation prints "FATAL: deadlock detected" and	131	ready coros to run. The default implementation prints "FATAL:
105	exits, because the program has no other way to continue.	132	deadlock detected" and exits, because the program has no other way to
		133	continue.
106		134
		135	If it is a coro object, then this object will be readied (without
		136	invoking any ready hooks, however) when the scheduler finds no other ready
		137	coros to run.
		138
107	This hook is overwritten by modules such as C<Coro::Timer> and	139	This hook is overwritten by modules such as C<Coro::EV> and
108	C<Coro::Event> to wait on an external event that hopefully wake up a	140	C<Coro::AnyEvent> to wait on an external event that hopefully wake up a
109	coroutine so the scheduler can run it.	141	coro so the scheduler can run it.
		142
		143	Note that the callback I<must not>, under any circumstances, block
		144	the current coro. Normally, this is achieved by having an "idle
		145	coro" that calls the event loop and then blocks again, and then
		146	readying that coro in the idle handler, or by simply placing the idle
		147	coro in this variable.
		148
		149	See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this
		150	technique.
110		151
111	Please note that if your callback recursively invokes perl (e.g. for event	152	Please note that if your callback recursively invokes perl (e.g. for event
112	handlers), then it must be prepared to be called recursively itself.	153	handlers), then it must be prepared to be called recursively itself.
113		154
114	=cut	155	=cut
…		…
116	$idle = sub {	157	$idle = sub {
117	require Carp;	158	require Carp;
118	Carp::croak ("FATAL: deadlock detected");	159	Carp::croak ("FATAL: deadlock detected");
119	};	160	};
120		161
121	sub _cancel {
122	my ($self) = @_;
123
124	# free coroutine data and mark as destructed
125	$self->_destroy
126	or return;
127
128	# call all destruction callbacks
129	$_->(@{$self->{_status}})
130	for @{(delete $self->{_on_destroy}) \|\| []};
131	}
132
133	# this coroutine is necessary because a coroutine	162	# this coro is necessary because a coro
134	# cannot destroy itself.	163	# cannot destroy itself.
135	my @destroy;	164	our @destroy;
136	my $manager;	165	our $manager;
137		166
138	$manager = new Coro sub {	167	$manager = new Coro sub {
139	while () {	168	while () {
140	(shift @destroy)->_cancel	169	Coro::State::cancel shift @destroy
141	while @destroy;	170	while @destroy;
142		171
143	&schedule;	172	&schedule;
144	}	173	}
145	};	174	};
146	$manager->desc ("[coro manager]");	175	$manager->{desc} = "[coro manager]";
147	$manager->prio (PRIO_MAX);	176	$manager->prio (PRIO_MAX);
148		177
149	=back	178	=back
150		179
151	=head2 STATIC METHODS	180	=head1 SIMPLE CORO CREATION
152
153	Static methods are actually functions that operate on the current coroutine only.
154		181
155	=over 4	182	=over 4
156		183
157	=item async { ... } [@args...]	184	=item async { ... } [@args...]
158		185
159	Create a new asynchronous coroutine and return it's coroutine object	186	Create a new coro and return its Coro object (usually
160	(usually unused). When the sub returns the new coroutine is automatically	187	unused). The coro will be put into the ready queue, so
		188	it will start running automatically on the next scheduler run.
		189
		190	The first argument is a codeblock/closure that should be executed in the
		191	coro. When it returns argument returns the coro is automatically
161	terminated.	192	terminated.
162		193
		194	The remaining arguments are passed as arguments to the closure.
		195
163	See the C<Coro::State::new> constructor for info about the coroutine	196	See the C<Coro::State::new> constructor for info about the coro
164	environment in which coroutines run.	197	environment in which coro are executed.
165		198
166	Calling C<exit> in a coroutine will do the same as calling exit outside	199	Calling C<exit> in a coro will do the same as calling exit outside
167	the coroutine. Likewise, when the coroutine dies, the program will exit,	200	the coro. Likewise, when the coro dies, the program will exit,
168	just as it would in the main program.	201	just as it would in the main program.
169		202
		203	If you do not want that, you can provide a default C<die> handler, or
		204	simply avoid dieing (by use of C<eval>).
		205
170	# create a new coroutine that just prints its arguments	206	Example: Create a new coro that just prints its arguments.
		207
171	async {	208	async {
172	print "@_\n";	209	print "@_\n";
173	} 1,2,3,4;	210	} 1,2,3,4;
174		211
175	=cut
176
177	sub async(&@) {
178	my $coro = new Coro @_;
179	$coro->ready;
180	$coro
181	}
182
183	=item async_pool { ... } [@args...]	212	=item async_pool { ... } [@args...]
184		213
185	Similar to C<async>, but uses a coroutine pool, so you should not call	214	Similar to C<async>, but uses a coro pool, so you should not call
186	terminate or join (although you are allowed to), and you get a coroutine	215	terminate or join on it (although you are allowed to), and you get a
187	that might have executed other code already (which can be good or bad :).	216	coro that might have executed other code already (which can be good
		217	or bad :).
188		218
		219	On the plus side, this function is about twice as fast as creating (and
		220	destroying) a completely new coro, so if you need a lot of generic
		221	coros in quick successsion, use C<async_pool>, not C<async>.
		222
189	Also, the block is executed in an C<eval> context and a warning will be	223	The code block is executed in an C<eval> context and a warning will be
190	issued in case of an exception instead of terminating the program, as	224	issued in case of an exception instead of terminating the program, as
191	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>	225	C<async> does. As the coro is being reused, stuff like C<on_destroy>
192	will not work in the expected way, unless you call terminate or cancel,	226	will not work in the expected way, unless you call terminate or cancel,
193	which somehow defeats the purpose of pooling.	227	which somehow defeats the purpose of pooling (but is fine in the
		228	exceptional case).
194		229
195	The priority will be reset to C<0> after each job, tracing will be	230	The priority will be reset to C<0> after each run, tracing will be
196	disabled, the description will be reset and the default output filehandle	231	disabled, the description will be reset and the default output filehandle
197	gets restored, so you can change alkl these. Otherwise the coroutine will	232	gets restored, so you can change all these. Otherwise the coro will
198	be re-used "as-is": most notably if you change other per-coroutine global	233	be re-used "as-is": most notably if you change other per-coro global
199	stuff such as C<$/> you need to revert that change, which is most simply	234	stuff such as C<$/> you I<must needs> revert that change, which is most
200	done by using local as in C< local $/ >.	235	simply done by using local as in: C<< local $/ >>.
201		236
202	The pool size is limited to 8 idle coroutines (this can be adjusted by	237	The idle pool size is limited to C<8> idle coros (this can be
203	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as	238	adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle
204	required.	239	coros as required.
205		240
206	If you are concerned about pooled coroutines growing a lot because a	241	If you are concerned about pooled coros growing a lot because a
207	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool	242	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
208	{ terminate }> once per second or so to slowly replenish the pool. In	243	{ terminate }> once per second or so to slowly replenish the pool. In
209	addition to that, when the stacks used by a handler grows larger than 16kb	244	addition to that, when the stacks used by a handler grows larger than 32kb
210	(adjustable with $Coro::POOL_RSS) it will also exit.	245	(adjustable via $Coro::POOL_RSS) it will also be destroyed.
211		246
212	=cut	247	=cut
213		248
214	our $POOL_SIZE = 8;	249	our $POOL_SIZE = 8;
215	our $POOL_RSS = 16 * 1024;	250	our $POOL_RSS = 32 * 1024;
216	our @async_pool;	251	our @async_pool;
217		252
218	sub pool_handler {	253	sub pool_handler {
219	my $cb;
220
221	while () {	254	while () {
222	eval {	255	eval {
223	while () {	256	&{&_pool_handler} while 1;
224	_pool_1 $cb;
225	&$cb;
226	_pool_2 $cb;
227	&schedule;
228	}
229	};	257	};
230		258
231	last if $@ eq "\3async_pool terminate\2\n";
232	warn $@ if $@;	259	warn $@ if $@;
233	}	260	}
234	}	261	}
235		262
236	sub async_pool(&@) {	263	=back
237	# this is also inlined into the unlock_scheduler
238	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
239		264
240	$coro->{_invoke} = [@_];	265	=head1 STATIC METHODS
241	$coro->ready;
242		266
243	$coro	267	Static methods are actually functions that implicitly operate on the
244	}	268	current coro.
		269
		270	=over 4
245		271
246	=item schedule	272	=item schedule
247		273
248	Calls the scheduler. Please note that the current coroutine will not be put	274	Calls the scheduler. The scheduler will find the next coro that is
		275	to be run from the ready queue and switches to it. The next coro
		276	to be run is simply the one with the highest priority that is longest
		277	in its ready queue. If there is no coro ready, it will clal the
		278	C<$Coro::idle> hook.
		279
		280	Please note that the current coro will I<not> be put into the ready
249	into the ready queue, so calling this function usually means you will	281	queue, so calling this function usually means you will never be called
250	never be called again unless something else (e.g. an event handler) calls	282	again unless something else (e.g. an event handler) calls C<< ->ready >>,
251	ready.	283	thus waking you up.
252		284
253	The canonical way to wait on external events is this:	285	This makes C<schedule> I<the> generic method to use to block the current
		286	coro and wait for events: first you remember the current coro in
		287	a variable, then arrange for some callback of yours to call C<< ->ready
		288	>> on that once some event happens, and last you call C<schedule> to put
		289	yourself to sleep. Note that a lot of things can wake your coro up,
		290	so you need to check whether the event indeed happened, e.g. by storing the
		291	status in a variable.
254		292
255	{	293	See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks.
256	# remember current coroutine
257	my $current = $Coro::current;
258		294
259	# register a hypothetical event handler	295	=item cede
260	on_event_invoke sub {	296
261	# wake up sleeping coroutine	297	"Cede" to other coros. This function puts the current coro into
262	$current->ready;	298	the ready queue and calls C<schedule>, which has the effect of giving
263	undef $current;	299	up the current "timeslice" to other coros of the same or higher
		300	priority. Once your coro gets its turn again it will automatically be
		301	resumed.
		302
		303	This function is often called C<yield> in other languages.
		304
		305	=item Coro::cede_notself
		306
		307	Works like cede, but is not exported by default and will cede to I<any>
		308	coro, regardless of priority. This is useful sometimes to ensure
		309	progress is made.
		310
		311	=item terminate [arg...]
		312
		313	Terminates the current coro with the given status values (see L<cancel>).
		314
		315	=item Coro::on_enter BLOCK, Coro::on_leave BLOCK
		316
		317	These function install enter and leave winders in the current scope. The
		318	enter block will be executed when on_enter is called and whenever the
		319	current coro is re-entered by the scheduler, while the leave block is
		320	executed whenever the current coro is blocked by the scheduler, and
		321	also when the containing scope is exited (by whatever means, be it exit,
		322	die, last etc.).
		323
		324	I<Neither invoking the scheduler, nor exceptions, are allowed within those
		325	BLOCKs>. That means: do not even think about calling C<die> without an
		326	eval, and do not even think of entering the scheduler in any way.
		327
		328	Since both BLOCKs are tied to the current scope, they will automatically
		329	be removed when the current scope exits.
		330
		331	These functions implement the same concept as C<dynamic-wind> in scheme
		332	does, and are useful when you want to localise some resource to a specific
		333	coro.
		334
		335	They slow down thread switching considerably for coros that use them
		336	(about 40% for a BLOCK with a single assignment, so thread switching is
		337	still reasonably fast if the handlers are fast).
		338
		339	These functions are best understood by an example: The following function
		340	will change the current timezone to "Antarctica/South_Pole", which
		341	requires a call to C<tzset>, but by using C<on_enter> and C<on_leave>,
		342	which remember/change the current timezone and restore the previous
		343	value, respectively, the timezone is only changed for the coro that
		344	installed those handlers.
		345
		346	use POSIX qw(tzset);
		347
		348	async {
		349	my $old_tz; # store outside TZ value here
		350
		351	Coro::on_enter {
		352	$old_tz = $ENV{TZ}; # remember the old value
		353
		354	$ENV{TZ} = "Antarctica/South_Pole";
		355	tzset; # enable new value
264	};	356	};
265		357
266	# call schedule until event occurred.	358	Coro::on_leave {
267	# in case we are woken up for other reasons	359	$ENV{TZ} = $old_tz;
268	# (current still defined), loop.	360	tzset; # restore old value
269	Coro::schedule while $current;	361	};
		362
		363	# at this place, the timezone is Antarctica/South_Pole,
		364	# without disturbing the TZ of any other coro.
270	}	365	};
271		366
272	=item cede	367	This can be used to localise about any resource (locale, uid, current
		368	working directory etc.) to a block, despite the existance of other
		369	coros.
273		370
274	"Cede" to other coroutines. This function puts the current coroutine into the	371	Another interesting example implements time-sliced multitasking using
275	ready queue and calls C<schedule>, which has the effect of giving up the	372	interval timers (this could obviously be optimised, but does the job):
276	current "timeslice" to other coroutines of the same or higher priority.
277		373
278	=item Coro::cede_notself	374	# "timeslice" the given block
		375	sub timeslice(&) {
		376	use Time::HiRes ();
279		377
280	Works like cede, but is not exported by default and will cede to any	378	Coro::on_enter {
281	coroutine, regardless of priority, once.	379	# on entering the thread, we set an VTALRM handler to cede
		380	$SIG{VTALRM} = sub { cede };
		381	# and then start the interval timer
		382	Time::HiRes::setitimer &Time::HiRes::ITIMER_VIRTUAL, 0.01, 0.01;
		383	};
		384	Coro::on_leave {
		385	# on leaving the thread, we stop the interval timer again
		386	Time::HiRes::setitimer &Time::HiRes::ITIMER_VIRTUAL, 0, 0;
		387	};
282		388
283	=item terminate [arg...]	389	&{+shift};
		390	}
284		391
285	Terminates the current coroutine with the given status values (see L<cancel>).	392	# use like this:
		393	timeslice {
		394	# The following is an endless loop that would normally
		395	# monopolise the process. Since it runs in a timesliced
		396	# environment, it will regularly cede to other threads.
		397	while () { }
		398	};
		399
286		400
287	=item killall	401	=item killall
288		402
289	Kills/terminates/cancels all coroutines except the currently running	403	Kills/terminates/cancels all coros except the currently running one.
290	one. This is useful after a fork, either in the child or the parent, as
291	usually only one of them should inherit the running coroutines.
292		404
293	=cut	405	Note that while this will try to free some of the main interpreter
		406	resources if the calling coro isn't the main coro, but one
		407	cannot free all of them, so if a coro that is not the main coro
		408	calls this function, there will be some one-time resource leak.
294		409
295	sub terminate {	410	=cut
296	$current->cancel (@_);
297	}
298		411
299	sub killall {	412	sub killall {
300	for (Coro::State::list) {	413	for (Coro::State::list) {
301	$_->cancel	414	$_->cancel
302	if $_ != $current && UNIVERSAL::isa $_, "Coro";	415	if $_ != $current && UNIVERSAL::isa $_, "Coro";
303	}	416	}
304	}	417	}
305		418
306	=back	419	=back
307		420
308	=head2 COROUTINE METHODS	421	=head1 CORO OBJECT METHODS
309		422
310	These are the methods you can call on coroutine objects.	423	These are the methods you can call on coro objects (or to create
		424	them).
311		425
312	=over 4	426	=over 4
313		427
314	=item new Coro \&sub [, @args...]	428	=item new Coro \&sub [, @args...]
315		429
316	Create a new coroutine and return it. When the sub returns the coroutine	430	Create a new coro and return it. When the sub returns, the coro
317	automatically terminates as if C<terminate> with the returned values were	431	automatically terminates as if C<terminate> with the returned values were
318	called. To make the coroutine run you must first put it into the ready queue	432	called. To make the coro run you must first put it into the ready
319	by calling the ready method.	433	queue by calling the ready method.
320		434
321	See C<async> and C<Coro::State::new> for additional info about the	435	See C<async> and C<Coro::State::new> for additional info about the
322	coroutine environment.	436	coro environment.
323		437
324	=cut	438	=cut
325		439
326	sub _run_coro {	440	sub _coro_run {
327	terminate &{+shift};	441	terminate &{+shift};
328	}	442	}
329		443
330	sub new {
331	my $class = shift;
332
333	$class->SUPER::new (\&_run_coro, @_)
334	}
335
336	=item $success = $coroutine->ready	444	=item $success = $coro->ready
337		445
338	Put the given coroutine into the ready queue (according to it's priority)	446	Put the given coro into the end of its ready queue (there is one
339	and return true. If the coroutine is already in the ready queue, do nothing	447	queue for each priority) and return true. If the coro is already in
340	and return false.	448	the ready queue, do nothing and return false.
341		449
		450	This ensures that the scheduler will resume this coro automatically
		451	once all the coro of higher priority and all coro of the same
		452	priority that were put into the ready queue earlier have been resumed.
		453
		454	=item $coro->suspend
		455
		456	Suspends the specified coro. A suspended coro works just like any other
		457	coro, except that the scheduler will not select a suspended coro for
		458	execution.
		459
		460	Suspending a coro can be useful when you want to keep the coro from
		461	running, but you don't want to destroy it, or when you want to temporarily
		462	freeze a coro (e.g. for debugging) to resume it later.
		463
		464	A scenario for the former would be to suspend all (other) coros after a
		465	fork and keep them alive, so their destructors aren't called, but new
		466	coros can be created.
		467
		468	=item $coro->resume
		469
		470	If the specified coro was suspended, it will be resumed. Note that when
		471	the coro was in the ready queue when it was suspended, it might have been
		472	unreadied by the scheduler, so an activation might have been lost.
		473
		474	To avoid this, it is best to put a suspended coro into the ready queue
		475	unconditionally, as every synchronisation mechanism must protect itself
		476	against spurious wakeups, and the one in the Coro family certainly do
		477	that.
		478
342	=item $is_ready = $coroutine->is_ready	479	=item $is_ready = $coro->is_ready
343		480
344	Return wether the coroutine is currently the ready queue or not,	481	Returns true iff the Coro object is in the ready queue. Unless the Coro
		482	object gets destroyed, it will eventually be scheduled by the scheduler.
345		483
		484	=item $is_running = $coro->is_running
		485
		486	Returns true iff the Coro object is currently running. Only one Coro object
		487	can ever be in the running state (but it currently is possible to have
		488	multiple running Coro::States).
		489
		490	=item $is_suspended = $coro->is_suspended
		491
		492	Returns true iff this Coro object has been suspended. Suspended Coros will
		493	not ever be scheduled.
		494
346	=item $coroutine->cancel (arg...)	495	=item $coro->cancel (arg...)
347		496
348	Terminates the given coroutine and makes it return the given arguments as	497	Terminates the given Coro and makes it return the given arguments as
349	status (default: the empty list). Never returns if the coroutine is the	498	status (default: the empty list). Never returns if the Coro is the
350	current coroutine.	499	current Coro.
351		500
352	=cut	501	=cut
353		502
354	sub cancel {	503	sub cancel {
355	my $self = shift;	504	my $self = shift;
356	$self->{_status} = [@_];
357		505
358	if ($current == $self) {	506	if ($current == $self) {
359	push @destroy, $self;	507	terminate @_;
360	$manager->ready;
361	&schedule while 1;
362	} else {	508	} else {
363	$self->_cancel;	509	$self->{_status} = [@_];
		510	Coro::State::cancel $self;
364	}	511	}
365	}	512	}
366		513
		514	=item $coro->schedule_to
		515
		516	Puts the current coro to sleep (like C<Coro::schedule>), but instead
		517	of continuing with the next coro from the ready queue, always switch to
		518	the given coro object (regardless of priority etc.). The readyness
		519	state of that coro isn't changed.
		520
		521	This is an advanced method for special cases - I'd love to hear about any
		522	uses for this one.
		523
		524	=item $coro->cede_to
		525
		526	Like C<schedule_to>, but puts the current coro into the ready
		527	queue. This has the effect of temporarily switching to the given
		528	coro, and continuing some time later.
		529
		530	This is an advanced method for special cases - I'd love to hear about any
		531	uses for this one.
		532
		533	=item $coro->throw ([$scalar])
		534
		535	If C<$throw> is specified and defined, it will be thrown as an exception
		536	inside the coro at the next convenient point in time. Otherwise
		537	clears the exception object.
		538
		539	Coro will check for the exception each time a schedule-like-function
		540	returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down
		541	>>, C<< Coro::Handle->readable >> and so on. Most of these functions
		542	detect this case and return early in case an exception is pending.
		543
		544	The exception object will be thrown "as is" with the specified scalar in
		545	C<$@>, i.e. if it is a string, no line number or newline will be appended
		546	(unlike with C<die>).
		547
		548	This can be used as a softer means than C<cancel> to ask a coro to
		549	end itself, although there is no guarantee that the exception will lead to
		550	termination, and if the exception isn't caught it might well end the whole
		551	program.
		552
		553	You might also think of C<throw> as being the moral equivalent of
		554	C<kill>ing a coro with a signal (in this case, a scalar).
		555
367	=item $coroutine->join	556	=item $coro->join
368		557
369	Wait until the coroutine terminates and return any values given to the	558	Wait until the coro terminates and return any values given to the
370	C<terminate> or C<cancel> functions. C<join> can be called concurrently	559	C<terminate> or C<cancel> functions. C<join> can be called concurrently
371	from multiple coroutines.	560	from multiple coro, and all will be resumed and given the status
		561	return once the C<$coro> terminates.
372		562
373	=cut	563	=cut
374		564
375	sub join {	565	sub join {
376	my $self = shift;	566	my $self = shift;
…		…
387	}	577	}
388		578
389	wantarray ? @{$self->{_status}} : $self->{_status}[0];	579	wantarray ? @{$self->{_status}} : $self->{_status}[0];
390	}	580	}
391		581
392	=item $coroutine->on_destroy (\&cb)	582	=item $coro->on_destroy (\&cb)
393		583
394	Registers a callback that is called when this coroutine gets destroyed,	584	Registers a callback that is called when this coro gets destroyed,
395	but before it is joined. The callback gets passed the terminate arguments,	585	but before it is joined. The callback gets passed the terminate arguments,
396	if any.	586	if any, and I<must not> die, under any circumstances.
397		587
398	=cut	588	=cut
399		589
400	sub on_destroy {	590	sub on_destroy {
401	my ($self, $cb) = @_;	591	my ($self, $cb) = @_;
402		592
403	push @{ $self->{_on_destroy} }, $cb;	593	push @{ $self->{_on_destroy} }, $cb;
404	}	594	}
405		595
406	=item $oldprio = $coroutine->prio ($newprio)	596	=item $oldprio = $coro->prio ($newprio)
407		597
408	Sets (or gets, if the argument is missing) the priority of the	598	Sets (or gets, if the argument is missing) the priority of the
409	coroutine. Higher priority coroutines get run before lower priority	599	coro. Higher priority coro get run before lower priority
410	coroutines. Priorities are small signed integers (currently -4 .. +3),	600	coro. Priorities are small signed integers (currently -4 .. +3),
411	that you can refer to using PRIO_xxx constants (use the import tag :prio	601	that you can refer to using PRIO_xxx constants (use the import tag :prio
412	to get then):	602	to get then):
413		603
414	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN	604	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
415	3 > 1 > 0 > -1 > -3 > -4	605	3 > 1 > 0 > -1 > -3 > -4
416		606
417	# set priority to HIGH	607	# set priority to HIGH
418	current->prio(PRIO_HIGH);	608	current->prio (PRIO_HIGH);
419		609
420	The idle coroutine ($Coro::idle) always has a lower priority than any	610	The idle coro ($Coro::idle) always has a lower priority than any
421	existing coroutine.	611	existing coro.
422		612
423	Changing the priority of the current coroutine will take effect immediately,	613	Changing the priority of the current coro will take effect immediately,
424	but changing the priority of coroutines in the ready queue (but not	614	but changing the priority of coro in the ready queue (but not
425	running) will only take effect after the next schedule (of that	615	running) will only take effect after the next schedule (of that
426	coroutine). This is a bug that will be fixed in some future version.	616	coro). This is a bug that will be fixed in some future version.
427		617
428	=item $newprio = $coroutine->nice ($change)	618	=item $newprio = $coro->nice ($change)
429		619
430	Similar to C<prio>, but subtract the given value from the priority (i.e.	620	Similar to C<prio>, but subtract the given value from the priority (i.e.
431	higher values mean lower priority, just as in unix).	621	higher values mean lower priority, just as in unix).
432		622
433	=item $olddesc = $coroutine->desc ($newdesc)	623	=item $olddesc = $coro->desc ($newdesc)
434		624
435	Sets (or gets in case the argument is missing) the description for this	625	Sets (or gets in case the argument is missing) the description for this
436	coroutine. This is just a free-form string you can associate with a coroutine.	626	coro. This is just a free-form string you can associate with a
		627	coro.
437		628
438	This method simply sets the C<< $coroutine->{desc} >> member to the given string. You	629	This method simply sets the C<< $coro->{desc} >> member to the given
439	can modify this member directly if you wish.	630	string. You can modify this member directly if you wish.
440
441	=item $coroutine->throw ([$scalar])
442
443	If C<$throw> is specified and defined, it will be thrown as an exception
444	inside the coroutine at the next convinient point in time (usually after
445	it gains control at the next schedule/transfer/cede). Otherwise clears the
446	exception object.
447
448	The exception object will be thrown "as is" with the specified scalar in
449	C<$@>, i.e. if it is a string, no line number or newline will be appended
450	(unlike with C<die>).
451
452	This can be used as a softer means than C<cancel> to ask a coroutine to
453	end itself, although there is no guarentee that the exception will lead to
454	termination, and if the exception isn't caught it might well end the whole
455	program.
456		631
457	=cut	632	=cut
458		633
459	sub desc {	634	sub desc {
460	my $old = $_[0]{desc};	635	my $old = $_[0]{desc};
461	$_[0]{desc} = $_[1] if @_ > 1;	636	$_[0]{desc} = $_[1] if @_ > 1;
462	$old;	637	$old;
463	}	638	}
464		639
		640	sub transfer {
		641	require Carp;
		642	Carp::croak ("You must not call ->transfer on Coro objects. Use Coro::State objects or the ->schedule_to method. Caught");
		643	}
		644
465	=back	645	=back
466		646
467	=head2 GLOBAL FUNCTIONS	647	=head1 GLOBAL FUNCTIONS
468		648
469	=over 4	649	=over 4
470		650
471	=item Coro::nready	651	=item Coro::nready
472		652
473	Returns the number of coroutines that are currently in the ready state,	653	Returns the number of coro that are currently in the ready state,
474	i.e. that can be switched to. The value C<0> means that the only runnable	654	i.e. that can be switched to by calling C<schedule> directory or
		655	indirectly. The value C<0> means that the only runnable coro is the
475	coroutine is the currently running one, so C<cede> would have no effect,	656	currently running one, so C<cede> would have no effect, and C<schedule>
476	and C<schedule> would cause a deadlock unless there is an idle handler	657	would cause a deadlock unless there is an idle handler that wakes up some
477	that wakes up some coroutines.	658	coro.
478		659
479	=item my $guard = Coro::guard { ... }	660	=item my $guard = Coro::guard { ... }
480		661
481	This creates and returns a guard object. Nothing happens until the object	662	This function still exists, but is deprecated. Please use the
482	gets destroyed, in which case the codeblock given as argument will be	663	C<Guard::guard> function instead.
483	executed. This is useful to free locks or other resources in case of a
484	runtime error or when the coroutine gets canceled, as in both cases the
485	guard block will be executed. The guard object supports only one method,
486	C<< ->cancel >>, which will keep the codeblock from being executed.
487		664
488	Example: set some flag and clear it again when the coroutine gets canceled
489	or the function returns:
490
491	sub do_something {
492	my $guard = Coro::guard { $busy = 0 };
493	$busy = 1;
494
495	# do something that requires $busy to be true
496	}
497
498	=cut	665	=cut
499		666
500	sub guard(&) {	667	BEGIN { *guard = \&Guard::guard }
501	bless \(my $cb = $_[0]), "Coro::guard"
502	}
503
504	sub Coro::guard::cancel {
505	${$_[0]} = sub { };
506	}
507
508	sub Coro::guard::DESTROY {
509	${$_[0]}->();
510	}
511
512		668
513	=item unblock_sub { ... }	669	=item unblock_sub { ... }
514		670
515	This utility function takes a BLOCK or code reference and "unblocks" it,	671	This utility function takes a BLOCK or code reference and "unblocks" it,
516	returning the new coderef. This means that the new coderef will return	672	returning a new coderef. Unblocking means that calling the new coderef
517	immediately without blocking, returning nothing, while the original code	673	will return immediately without blocking, returning nothing, while the
518	ref will be called (with parameters) from within its own coroutine.	674	original code ref will be called (with parameters) from within another
		675	coro.
519		676
520	The reason this function exists is that many event libraries (such as the	677	The reason this function exists is that many event libraries (such as the
521	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form	678	venerable L<Event\|Event> module) are not thread-safe (a weaker form
522	of thread-safety). This means you must not block within event callbacks,	679	of reentrancy). This means you must not block within event callbacks,
523	otherwise you might suffer from crashes or worse.	680	otherwise you might suffer from crashes or worse. The only event library
		681	currently known that is safe to use without C<unblock_sub> is L<EV>.
524		682
525	This function allows your callbacks to block by executing them in another	683	This function allows your callbacks to block by executing them in another
526	coroutine where it is safe to block. One example where blocking is handy	684	coro where it is safe to block. One example where blocking is handy
527	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to	685	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
528	disk.	686	disk, for example.
529		687
530	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when	688	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
531	creating event callbacks that want to block.	689	creating event callbacks that want to block.
		690
		691	If your handler does not plan to block (e.g. simply sends a message to
		692	another coro, or puts some other coro into the ready queue), there is
		693	no reason to use C<unblock_sub>.
		694
		695	Note that you also need to use C<unblock_sub> for any other callbacks that
		696	are indirectly executed by any C-based event loop. For example, when you
		697	use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it
		698	provides callbacks that are the result of some event callback, then you
		699	must not block either, or use C<unblock_sub>.
532		700
533	=cut	701	=cut
534		702
535	our @unblock_queue;	703	our @unblock_queue;
536		704
…		…
539	# return immediately and can be reused) and because we cannot cede	707	# return immediately and can be reused) and because we cannot cede
540	# inside an event callback.	708	# inside an event callback.
541	our $unblock_scheduler = new Coro sub {	709	our $unblock_scheduler = new Coro sub {
542	while () {	710	while () {
543	while (my $cb = pop @unblock_queue) {	711	while (my $cb = pop @unblock_queue) {
544	# this is an inlined copy of async_pool	712	&async_pool (@$cb);
545	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
546		713
547	$coro->{_invoke} = $cb;
548	$coro->ready;
549	cede; # for short-lived callbacks, this reduces pressure on the coro pool	714	# for short-lived callbacks, this reduces pressure on the coro pool
		715	# as the chance is very high that the async_poll coro will be back
		716	# in the idle state when cede returns
		717	cede;
550	}	718	}
551	schedule; # sleep well	719	schedule; # sleep well
552	}	720	}
553	};	721	};
554	$unblock_scheduler->desc ("[unblock_sub scheduler]");	722	$unblock_scheduler->{desc} = "[unblock_sub scheduler]";
555		723
556	sub unblock_sub(&) {	724	sub unblock_sub(&) {
557	my $cb = shift;	725	my $cb = shift;
558		726
559	sub {	727	sub {
560	unshift @unblock_queue, [$cb, @_];	728	unshift @unblock_queue, [$cb, @_];
561	$unblock_scheduler->ready;	729	$unblock_scheduler->ready;
562	}	730	}
563	}	731	}
564		732
		733	=item $cb = Coro::rouse_cb
		734
		735	Create and return a "rouse callback". That's a code reference that,
		736	when called, will remember a copy of its arguments and notify the owner
		737	coro of the callback.
		738
		739	See the next function.
		740
		741	=item @args = Coro::rouse_wait [$cb]
		742
		743	Wait for the specified rouse callback (or the last one that was created in
		744	this coro).
		745
		746	As soon as the callback is invoked (or when the callback was invoked
		747	before C<rouse_wait>), it will return the arguments originally passed to
		748	the rouse callback. In scalar context, that means you get the I<last>
		749	argument, just as if C<rouse_wait> had a C<return ($a1, $a2, $a3...)>
		750	statement at the end.
		751
		752	See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example.
		753
565	=back	754	=back
566		755
567	=cut	756	=cut
568		757
569	1;	758	1;
570		759
		760	=head1 HOW TO WAIT FOR A CALLBACK
		761
		762	It is very common for a coro to wait for some callback to be
		763	called. This occurs naturally when you use coro in an otherwise
		764	event-based program, or when you use event-based libraries.
		765
		766	These typically register a callback for some event, and call that callback
		767	when the event occured. In a coro, however, you typically want to
		768	just wait for the event, simplyifying things.
		769
		770	For example C<< AnyEvent->child >> registers a callback to be called when
		771	a specific child has exited:
		772
		773	my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... });
		774
		775	But from within a coro, you often just want to write this:
		776
		777	my $status = wait_for_child $pid;
		778
		779	Coro offers two functions specifically designed to make this easy,
		780	C<Coro::rouse_cb> and C<Coro::rouse_wait>.
		781
		782	The first function, C<rouse_cb>, generates and returns a callback that,
		783	when invoked, will save its arguments and notify the coro that
		784	created the callback.
		785
		786	The second function, C<rouse_wait>, waits for the callback to be called
		787	(by calling C<schedule> to go to sleep) and returns the arguments
		788	originally passed to the callback.
		789
		790	Using these functions, it becomes easy to write the C<wait_for_child>
		791	function mentioned above:
		792
		793	sub wait_for_child($) {
		794	my ($pid) = @_;
		795
		796	my $watcher = AnyEvent->child (pid => $pid, cb => Coro::rouse_cb);
		797
		798	my ($rpid, $rstatus) = Coro::rouse_wait;
		799	$rstatus
		800	}
		801
		802	In the case where C<rouse_cb> and C<rouse_wait> are not flexible enough,
		803	you can roll your own, using C<schedule>:
		804
		805	sub wait_for_child($) {
		806	my ($pid) = @_;
		807
		808	# store the current coro in $current,
		809	# and provide result variables for the closure passed to ->child
		810	my $current = $Coro::current;
		811	my ($done, $rstatus);
		812
		813	# pass a closure to ->child
		814	my $watcher = AnyEvent->child (pid => $pid, cb => sub {
		815	$rstatus = $_[1]; # remember rstatus
		816	$done = 1; # mark $rstatus as valud
		817	});
		818
		819	# wait until the closure has been called
		820	schedule while !$done;
		821
		822	$rstatus
		823	}
		824
		825
571	=head1 BUGS/LIMITATIONS	826	=head1 BUGS/LIMITATIONS
572		827
573	- you must make very sure that no coro is still active on global	828	=over 4
574	destruction. very bad things might happen otherwise (usually segfaults).
575		829
		830	=item fork with pthread backend
		831
		832	When Coro is compiled using the pthread backend (which isn't recommended
		833	but required on many BSDs as their libcs are completely broken), then
		834	coro will not survive a fork. There is no known workaround except to
		835	fix your libc and use a saner backend.
		836
		837	=item perl process emulation ("threads")
		838
576	- this module is not thread-safe. You should only ever use this module	839	This module is not perl-pseudo-thread-safe. You should only ever use this
577	from the same thread (this requirement might be loosened in the future	840	module from the first thread (this requirement might be removed in the
578	to allow per-thread schedulers, but Coro::State does not yet allow	841	future to allow per-thread schedulers, but Coro::State does not yet allow
579	this).	842	this). I recommend disabling thread support and using processes, as having
		843	the windows process emulation enabled under unix roughly halves perl
		844	performance, even when not used.
		845
		846	=item coro switching is not signal safe
		847
		848	You must not switch to another coro from within a signal handler
		849	(only relevant with %SIG - most event libraries provide safe signals).
		850
		851	That means you I<MUST NOT> call any function that might "block" the
		852	current coro - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or
		853	anything that calls those. Everything else, including calling C<ready>,
		854	works.
		855
		856	=back
		857
580		858
581	=head1 SEE ALSO	859	=head1 SEE ALSO
582		860
583	Lower level Configuration, Coroutine Environment: L<Coro::State>.	861	Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
584		862
585	Debugging: L<Coro::Debug>.	863	Debugging: L<Coro::Debug>.
586		864
587	Support/Utility: L<Coro::Specific>, L<Coro::Util>.	865	Support/Utility: L<Coro::Specific>, L<Coro::Util>.
588		866
589	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.	867	Locking and IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>,
		868	L<Coro::SemaphoreSet>, L<Coro::RWLock>.
590		869
591	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>.	870	I/O and Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>.
592		871
593	Compatibility: L<Coro::LWP>, L<Coro::Storable>, L<Coro::Select>.	872	Compatibility with other modules: L<Coro::LWP> (but see also L<AnyEvent::HTTP> for
		873	a better-working alternative), L<Coro::BDB>, L<Coro::Storable>,
		874	L<Coro::Select>.
594		875
595	Embedding: L<Coro::MakeMaker>.	876	XS API: L<Coro::MakeMaker>.
		877
		878	Low level Configuration, Thread Environment, Continuations: L<Coro::State>.
596		879
597	=head1 AUTHOR	880	=head1 AUTHOR
598		881
599	Marc Lehmann <schmorp@schmorp.de>	882	Marc Lehmann <schmorp@schmorp.de>
600	http://home.schmorp.de/	883	http://home.schmorp.de/

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Comparing cvsroot/Coro/Coro.pm (file contents): Revision 1.180 by root, Fri Apr 25 04:28:50 2008 UTC vs. Revision 1.264 by root, Thu Aug 13 02:35:41 2009 UTC

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Comparing cvsroot/Coro/Coro.pm (file contents):
Revision 1.180 by root, Fri Apr 25 04:28:50 2008 UTC vs.
Revision 1.264 by root, Thu Aug 13 02:35:41 2009 UTC