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

Comparing Coro/Coro.pm (file contents):
Revision 1.144 by root, Wed Oct 3 01:48:05 2007 UTC vs.
Revision 1.258 by root, Fri Jun 26 14:25:45 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
9	async {	9	async {
10	# some asynchronous thread of execution	10	# some asynchronous thread of execution
		11	print "2\n";
		12	cede; # yield back to main
		13	print "4\n";
11	};	14	};
12		15	print "1\n";
13	# alternatively create an async coroutine like this:	16	cede; # yield to coro
14		17	print "3\n";
15	sub some_func : Coro {	18	cede; # and again
16	# some more async code	19
17	}	20	# use locking
18		21	use Coro::Semaphore;
19	cede;	22	my $lock = new Coro::Semaphore;
		23	my $locked;
		24
		25	$lock->down;
		26	$locked = 1;
		27	$lock->up;
20		28
21	=head1 DESCRIPTION	29	=head1 DESCRIPTION
22		30
23	This module collection manages coroutines. Coroutines are similar	31	For a tutorial-style introduction, please read the L<Coro::Intro>
24	to threads but don't run in parallel at the same time even on SMP	32	manpage. This manpage mainly contains reference information.
25	machines. The specific flavor of coroutine used in this module also
26	guarantees you that it will not switch between coroutines unless
27	necessary, at easily-identified points in your program, so locking and
28	parallel access are rarely an issue, making coroutine programming much
29	safer than threads programming.
30		33
31	(Perl, however, does not natively support real threads but instead does a	34	This module collection manages continuations in general, most often in
32	very slow and memory-intensive emulation of processes using threads. This	35	the form of cooperative threads (also called coros, or simply "coro"
33	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.
34		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
35	In this module, coroutines are defined as "callchain + lexical variables +	60	In this module, a thread is defined as "callchain + lexical variables +
36	@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,	61	some package variables + C stack), that is, a thread has its own callchain,
37	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
38	variables.	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.
39		67
40	=cut	68	=cut
41		69
42	package Coro;	70	package Coro;
43		71
44	use strict;	72	use strict qw(vars subs);
45	no warnings "uninitialized";	73	no warnings "uninitialized";
46		74
		75	use Guard ();
		76
47	use Coro::State;	77	use Coro::State;
48		78
49	use base qw(Coro::State Exporter);	79	use base qw(Coro::State Exporter);
50		80
51	our $idle; # idle handler	81	our $idle; # idle handler
52	our $main; # main coroutine	82	our $main; # main coro
53	our $current; # current coroutine	83	our $current; # current coro
54		84
55	our $VERSION = '4.0';	85	our $VERSION = 5.14;
56		86
57	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);	87	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
58	our %EXPORT_TAGS = (	88	our %EXPORT_TAGS = (
59	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	89	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
60	);	90	);
61	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));	91	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
62		92
63	{	93	=head1 GLOBAL VARIABLES
64	my @async;
65	my $init;
66
67	# this way of handling attributes simply is NOT scalable ;()
68	sub import {
69	no strict 'refs';
70
71	Coro->export_to_level (1, @_);
72
73	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
74	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
75	my ($package, $ref) = (shift, shift);
76	my @attrs;
77	for (@_) {
78	if ($_ eq "Coro") {
79	push @async, $ref;
80	unless ($init++) {
81	eval q{
82	sub INIT {
83	&async(pop @async) while @async;
84	}
85	};
86	}
87	} else {
88	push @attrs, $_;
89	}
90	}
91	return $old ? $old->($package, $ref, @attrs) : @attrs;
92	};
93	}
94
95	}
96		94
97	=over 4	95	=over 4
98		96
99	=item $main	97	=item $Coro::main
100		98
101	This coroutine represents the main program.	99	This variable stores the Coro object that represents the main
		100	program. While you cna C<ready> it and do most other things you can do to
		101	coro, it is mainly useful to compare again C<$Coro::current>, to see
		102	whether you are running in the main program or not.
102		103
103	=cut	104	=cut
104		105
105	$main = new Coro;	106	# $main is now being initialised by Coro::State
106		107
107	=item $current (or as function: current)	108	=item $Coro::current
108		109
109	The current coroutine (the last coroutine switched to). The initial value	110	The Coro object representing the current coro (the last
		111	coro that the Coro scheduler switched to). The initial value is
110	is C<$main> (of course).	112	C<$Coro::main> (of course).
111		113
112	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
113	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
114	C<Coro::current> function instead.	116	not otherwise modify the variable itself.
115		117
116	=cut	118	=cut
117		119
118	$main->{desc} = "[main::]";
119
120	# maybe some other module used Coro::Specific before...
121	$main->{_specific} = $current->{_specific}
122	if $current;
123
124	_set_current $main;
125
126	sub current() { $current }	120	sub current() { $current } # [DEPRECATED]
127		121
128	=item $idle	122	=item $Coro::idle
129		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
130	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
131	to run. The default implementation prints "FATAL: deadlock detected" and	131	ready coros to run. The default implementation prints "FATAL:
132	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.
133		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
134	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
135	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
136	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.
137		151
138	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
139	handlers), then it must be prepared to be called recursively.	153	handlers), then it must be prepared to be called recursively itself.
140		154
141	=cut	155	=cut
142		156
143	$idle = sub {	157	$idle = sub {
144	require Carp;	158	require Carp;
145	Carp::croak ("FATAL: deadlock detected");	159	Carp::croak ("FATAL: deadlock detected");
146	};	160	};
147		161
148	sub _cancel {
149	my ($self) = @_;
150
151	# free coroutine data and mark as destructed
152	$self->_destroy
153	or return;
154
155	# call all destruction callbacks
156	$_->(@{$self->{_status}})
157	for @{(delete $self->{_on_destroy}) \|\| []};
158	}
159
160	# this coroutine is necessary because a coroutine	162	# this coro is necessary because a coro
161	# cannot destroy itself.	163	# cannot destroy itself.
162	my @destroy;	164	our @destroy;
163	my $manager;	165	our $manager;
164		166
165	$manager = new Coro sub {	167	$manager = new Coro sub {
166	while () {	168	while () {
167	(shift @destroy)->_cancel	169	Coro::State::cancel shift @destroy
168	while @destroy;	170	while @destroy;
169		171
170	&schedule;	172	&schedule;
171	}	173	}
172	};	174	};
173	$manager->desc ("[coro manager]");	175	$manager->{desc} = "[coro manager]";
174	$manager->prio (PRIO_MAX);	176	$manager->prio (PRIO_MAX);
175		177
176	# static methods. not really.
177
178	=back	178	=back
179		179
180	=head2 STATIC METHODS	180	=head1 SIMPLE CORO CREATION
181
182	Static methods are actually functions that operate on the current coroutine only.
183		181
184	=over 4	182	=over 4
185		183
186	=item async { ... } [@args...]	184	=item async { ... } [@args...]
187		185
188	Create a new asynchronous coroutine and return it's coroutine object	186	Create a new coro and return its Coro object (usually
189	(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
190	terminated.	192	terminated.
191		193
		194	The remaining arguments are passed as arguments to the closure.
		195
		196	See the C<Coro::State::new> constructor for info about the coro
		197	environment in which coro are executed.
		198
192	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
193	the coroutine. Likewise, when the coroutine dies, the program will exit,	200	the coro. Likewise, when the coro dies, the program will exit,
194	just as it would in the main program.	201	just as it would in the main program.
195		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
196	# create a new coroutine that just prints its arguments	206	Example: Create a new coro that just prints its arguments.
		207
197	async {	208	async {
198	print "@_\n";	209	print "@_\n";
199	} 1,2,3,4;	210	} 1,2,3,4;
200		211
201	=cut	212	=cut
206	$coro	217	$coro
207	}	218	}
208		219
209	=item async_pool { ... } [@args...]	220	=item async_pool { ... } [@args...]
210		221
211	Similar to C<async>, but uses a coroutine pool, so you should not call	222	Similar to C<async>, but uses a coro pool, so you should not call
212	terminate or join (although you are allowed to), and you get a coroutine	223	terminate or join on it (although you are allowed to), and you get a
213	that might have executed other code already (which can be good or bad :).	224	coro that might have executed other code already (which can be good
		225	or bad :).
214		226
		227	On the plus side, this function is about twice as fast as creating (and
		228	destroying) a completely new coro, so if you need a lot of generic
		229	coros in quick successsion, use C<async_pool>, not C<async>.
		230
215	Also, the block is executed in an C<eval> context and a warning will be	231	The code block is executed in an C<eval> context and a warning will be
216	issued in case of an exception instead of terminating the program, as	232	issued in case of an exception instead of terminating the program, as
217	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>	233	C<async> does. As the coro is being reused, stuff like C<on_destroy>
218	will not work in the expected way, unless you call terminate or cancel,	234	will not work in the expected way, unless you call terminate or cancel,
219	which somehow defeats the purpose of pooling.	235	which somehow defeats the purpose of pooling (but is fine in the
		236	exceptional case).
220		237
221	The priority will be reset to C<0> after each job, otherwise the coroutine	238	The priority will be reset to C<0> after each run, tracing will be
222	will be re-used "as-is".	239	disabled, the description will be reset and the default output filehandle
		240	gets restored, so you can change all these. Otherwise the coro will
		241	be re-used "as-is": most notably if you change other per-coro global
		242	stuff such as C<$/> you I<must needs> revert that change, which is most
		243	simply done by using local as in: C<< local $/ >>.
223		244
224	The pool size is limited to 8 idle coroutines (this can be adjusted by	245	The idle pool size is limited to C<8> idle coros (this can be
225	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as	246	adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle
226	required.	247	coros as required.
227		248
228	If you are concerned about pooled coroutines growing a lot because a	249	If you are concerned about pooled coros growing a lot because a
229	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool	250	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
230	{ terminate }> once per second or so to slowly replenish the pool. In	251	{ terminate }> once per second or so to slowly replenish the pool. In
231	addition to that, when the stacks used by a handler grows larger than 16kb	252	addition to that, when the stacks used by a handler grows larger than 32kb
232	(adjustable with $Coro::POOL_RSS) it will also exit.	253	(adjustable via $Coro::POOL_RSS) it will also be destroyed.
233		254
234	=cut	255	=cut
235		256
236	our $POOL_SIZE = 8;	257	our $POOL_SIZE = 8;
237	our $POOL_RSS = 16 * 1024;	258	our $POOL_RSS = 32 * 1024;
238	our @async_pool;	259	our @async_pool;
239		260
240	sub pool_handler {	261	sub pool_handler {
241	my $cb;
242
243	while () {	262	while () {
244	eval {	263	eval {
245	while () {	264	&{&_pool_handler} while 1;
246	_pool_1 $cb;
247	&$cb;
248	_pool_2 $cb;
249	&schedule;
250	}
251	};	265	};
252		266
253	last if $@ eq "\3terminate\2\n";
254	warn $@ if $@;	267	warn $@ if $@;
255	}	268	}
256	}	269	}
257		270
258	sub async_pool(&@) {	271	=back
259	# this is also inlined into the unlock_scheduler
260	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
261		272
262	$coro->{_invoke} = [@_];	273	=head1 STATIC METHODS
263	$coro->ready;
264		274
265	$coro	275	Static methods are actually functions that implicitly operate on the
266	}	276	current coro.
		277
		278	=over 4
267		279
268	=item schedule	280	=item schedule
269		281
270	Calls the scheduler. Please note that the current coroutine will not be put	282	Calls the scheduler. The scheduler will find the next coro that is
		283	to be run from the ready queue and switches to it. The next coro
		284	to be run is simply the one with the highest priority that is longest
		285	in its ready queue. If there is no coro ready, it will clal the
		286	C<$Coro::idle> hook.
		287
		288	Please note that the current coro will I<not> be put into the ready
271	into the ready queue, so calling this function usually means you will	289	queue, so calling this function usually means you will never be called
272	never be called again unless something else (e.g. an event handler) calls	290	again unless something else (e.g. an event handler) calls C<< ->ready >>,
273	ready.	291	thus waking you up.
274		292
275	The canonical way to wait on external events is this:	293	This makes C<schedule> I<the> generic method to use to block the current
		294	coro and wait for events: first you remember the current coro in
		295	a variable, then arrange for some callback of yours to call C<< ->ready
		296	>> on that once some event happens, and last you call C<schedule> to put
		297	yourself to sleep. Note that a lot of things can wake your coro up,
		298	so you need to check whether the event indeed happened, e.g. by storing the
		299	status in a variable.
276		300
277	{	301	See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks.
278	# remember current coroutine
279	my $current = $Coro::current;
280		302
281	# register a hypothetical event handler	303	=item cede
282	on_event_invoke sub {	304
283	# wake up sleeping coroutine	305	"Cede" to other coros. This function puts the current coro into
284	$current->ready;	306	the ready queue and calls C<schedule>, which has the effect of giving
285	undef $current;	307	up the current "timeslice" to other coros of the same or higher
		308	priority. Once your coro gets its turn again it will automatically be
		309	resumed.
		310
		311	This function is often called C<yield> in other languages.
		312
		313	=item Coro::cede_notself
		314
		315	Works like cede, but is not exported by default and will cede to I<any>
		316	coro, regardless of priority. This is useful sometimes to ensure
		317	progress is made.
		318
		319	=item terminate [arg...]
		320
		321	Terminates the current coro with the given status values (see L<cancel>).
		322
		323	=item Coro::on_enter BLOCK, Coro::on_leave BLOCK
		324
		325	These function install enter and leave winders in the current scope. The
		326	enter block will be executed when on_enter is called and whenever the
		327	current coro is re-entered by the scheduler, while the leave block is
		328	executed whenever the current coro is blocked by the scheduler, and
		329	also when the containing scope is exited (by whatever means, be it exit,
		330	die, last etc.).
		331
		332	I<Neither invoking the scheduler, nor exceptions, are allowed within those
		333	BLOCKs>. That means: do not even think about calling C<die> without an
		334	eval, and do not even think of entering the scheduler in any way.
		335
		336	Since both BLOCKs are tied to the current scope, they will automatically
		337	be removed when the current scope exits.
		338
		339	These functions implement the same concept as C<dynamic-wind> in scheme
		340	does, and are useful when you want to localise some resource to a specific
		341	coro.
		342
		343	They slow down thread switching considerably for coros that use them
		344	(about 40% for a BLOCK with a single assignment, so thread switching is
		345	still reasonably fast if the handlers are fast).
		346
		347	These functions are best understood by an example: The following function
		348	will change the current timezone to "Antarctica/South_Pole", which
		349	requires a call to C<tzset>, but by using C<on_enter> and C<on_leave>,
		350	which remember/change the current timezone and restore the previous
		351	value, respectively, the timezone is only changed for the coro that
		352	installed those handlers.
		353
		354	use POSIX qw(tzset);
		355
		356	async {
		357	my $old_tz; # store outside TZ value here
		358
		359	Coro::on_enter {
		360	$old_tz = $ENV{TZ}; # remember the old value
		361
		362	$ENV{TZ} = "Antarctica/South_Pole";
		363	tzset; # enable new value
286	};	364	};
287		365
288	# call schedule until event occurred.	366	Coro::on_leave {
289	# in case we are woken up for other reasons	367	$ENV{TZ} = $old_tz;
290	# (current still defined), loop.	368	tzset; # restore old value
291	Coro::schedule while $current;	369	};
		370
		371	# at this place, the timezone is Antarctica/South_Pole,
		372	# without disturbing the TZ of any other coro.
292	}	373	};
293		374
294	=item cede	375	This can be used to localise about any resource (locale, uid, current
		376	working directory etc.) to a block, despite the existance of other
		377	coros.
295		378
296	"Cede" to other coroutines. This function puts the current coroutine into the	379	Another interesting example implements time-sliced multitasking using
297	ready queue and calls C<schedule>, which has the effect of giving up the	380	interval timers (this could obviously be optimised, but does the job):
298	current "timeslice" to other coroutines of the same or higher priority.
299		381
300	Returns true if at least one coroutine switch has happened.	382	# "timeslice" the given block
		383	sub timeslice(&) {
		384	use Time::HiRes ();
301		385
302	=item Coro::cede_notself	386	Coro::on_enter {
		387	# on entering the thread, we set an VTALRM handler to cede
		388	$SIG{VTALRM} = sub { cede };
		389	# and then start the interval timer
		390	Time::HiRes::setitimer &Time::HiRes::ITIMER_VIRTUAL, 0.01, 0.01;
		391	};
		392	Coro::on_leave {
		393	# on leaving the thread, we stop the interval timer again
		394	Time::HiRes::setitimer &Time::HiRes::ITIMER_VIRTUAL, 0, 0;
		395	};
303		396
304	Works like cede, but is not exported by default and will cede to any	397	&{+shift};
305	coroutine, regardless of priority, once.	398	}
306		399
307	Returns true if at least one coroutine switch has happened.	400	# use like this:
		401	timeslice {
		402	# The following is an endless loop that would normally
		403	# monopolise the process. Since it runs in a timesliced
		404	# environment, it will regularly cede to other threads.
		405	while () { }
		406	};
308		407
309	=item terminate [arg...]
310
311	Terminates the current coroutine with the given status values (see L<cancel>).
312		408
313	=item killall	409	=item killall
314		410
315	Kills/terminates/cancels all coroutines except the currently running	411	Kills/terminates/cancels all coros except the currently running one.
316	one. This is useful after a fork, either in the child or the parent, as
317	usually only one of them should inherit the running coroutines.
318		412
319	=cut	413	Note that while this will try to free some of the main interpreter
		414	resources if the calling coro isn't the main coro, but one
		415	cannot free all of them, so if a coro that is not the main coro
		416	calls this function, there will be some one-time resource leak.
320		417
321	sub terminate {	418	=cut
322	$current->cancel (@_);
323	}
324		419
325	sub killall {	420	sub killall {
326	for (Coro::State::list) {	421	for (Coro::State::list) {
327	$_->cancel	422	$_->cancel
328	if $_ != $current && UNIVERSAL::isa $_, "Coro";	423	if $_ != $current && UNIVERSAL::isa $_, "Coro";
329	}	424	}
330	}	425	}
331		426
332	=back	427	=back
333		428
334	# dynamic methods
335
336	=head2 COROUTINE METHODS	429	=head1 CORO OBJECT METHODS
337		430
338	These are the methods you can call on coroutine objects.	431	These are the methods you can call on coro objects (or to create
		432	them).
339		433
340	=over 4	434	=over 4
341		435
342	=item new Coro \&sub [, @args...]	436	=item new Coro \&sub [, @args...]
343		437
344	Create a new coroutine and return it. When the sub returns the coroutine	438	Create a new coro and return it. When the sub returns, the coro
345	automatically terminates as if C<terminate> with the returned values were	439	automatically terminates as if C<terminate> with the returned values were
346	called. To make the coroutine run you must first put it into the ready queue	440	called. To make the coro run you must first put it into the ready
347	by calling the ready method.	441	queue by calling the ready method.
348		442
349	See C<async> for additional discussion.	443	See C<async> and C<Coro::State::new> for additional info about the
		444	coro environment.
350		445
351	=cut	446	=cut
352		447
353	sub _run_coro {	448	sub _coro_run {
354	terminate &{+shift};	449	terminate &{+shift};
355	}	450	}
356		451
357	sub new {
358	my $class = shift;
359
360	$class->SUPER::new (\&_run_coro, @_)
361	}
362
363	=item $success = $coroutine->ready	452	=item $success = $coro->ready
364		453
365	Put the given coroutine into the ready queue (according to it's priority)	454	Put the given coro into the end of its ready queue (there is one
366	and return true. If the coroutine is already in the ready queue, do nothing	455	queue for each priority) and return true. If the coro is already in
367	and return false.	456	the ready queue, do nothing and return false.
368		457
		458	This ensures that the scheduler will resume this coro automatically
		459	once all the coro of higher priority and all coro of the same
		460	priority that were put into the ready queue earlier have been resumed.
		461
		462	=item $coro->suspend
		463
		464	Suspends the specified coro. A suspended coro works just like any other
		465	coro, except that the scheduler will not select a suspended coro for
		466	execution.
		467
		468	Suspending a coro can be useful when you want to keep the coro from
		469	running, but you don't want to destroy it, or when you want to temporarily
		470	freeze a coro (e.g. for debugging) to resume it later.
		471
		472	A scenario for the former would be to suspend all (other) coros after a
		473	fork and keep them alive, so their destructors aren't called, but new
		474	coros can be created.
		475
		476	=item $coro->resume
		477
		478	If the specified coro was suspended, it will be resumed. Note that when
		479	the coro was in the ready queue when it was suspended, it might have been
		480	unreadied by the scheduler, so an activation might have been lost.
		481
		482	To avoid this, it is best to put a suspended coro into the ready queue
		483	unconditionally, as every synchronisation mechanism must protect itself
		484	against spurious wakeups, and the one in the Coro family certainly do
		485	that.
		486
369	=item $is_ready = $coroutine->is_ready	487	=item $is_ready = $coro->is_ready
370		488
371	Return wether the coroutine is currently the ready queue or not,	489	Returns true iff the Coro object is in the ready queue. Unless the Coro
		490	object gets destroyed, it will eventually be scheduled by the scheduler.
372		491
		492	=item $is_running = $coro->is_running
		493
		494	Returns true iff the Coro object is currently running. Only one Coro object
		495	can ever be in the running state (but it currently is possible to have
		496	multiple running Coro::States).
		497
		498	=item $is_suspended = $coro->is_suspended
		499
		500	Returns true iff this Coro object has been suspended. Suspended Coros will
		501	not ever be scheduled.
		502
373	=item $coroutine->cancel (arg...)	503	=item $coro->cancel (arg...)
374		504
375	Terminates the given coroutine and makes it return the given arguments as	505	Terminates the given Coro and makes it return the given arguments as
376	status (default: the empty list). Never returns if the coroutine is the	506	status (default: the empty list). Never returns if the Coro is the
377	current coroutine.	507	current Coro.
378		508
379	=cut	509	=cut
380		510
381	sub cancel {	511	sub cancel {
382	my $self = shift;	512	my $self = shift;
383	$self->{_status} = [@_];
384		513
385	if ($current == $self) {	514	if ($current == $self) {
386	push @destroy, $self;	515	terminate @_;
387	$manager->ready;
388	&schedule while 1;
389	} else {	516	} else {
390	$self->_cancel;	517	$self->{_status} = [@_];
		518	Coro::State::cancel $self;
391	}	519	}
392	}	520	}
393		521
		522	=item $coro->schedule_to
		523
		524	Puts the current coro to sleep (like C<Coro::schedule>), but instead
		525	of continuing with the next coro from the ready queue, always switch to
		526	the given coro object (regardless of priority etc.). The readyness
		527	state of that coro isn't changed.
		528
		529	This is an advanced method for special cases - I'd love to hear about any
		530	uses for this one.
		531
		532	=item $coro->cede_to
		533
		534	Like C<schedule_to>, but puts the current coro into the ready
		535	queue. This has the effect of temporarily switching to the given
		536	coro, and continuing some time later.
		537
		538	This is an advanced method for special cases - I'd love to hear about any
		539	uses for this one.
		540
		541	=item $coro->throw ([$scalar])
		542
		543	If C<$throw> is specified and defined, it will be thrown as an exception
		544	inside the coro at the next convenient point in time. Otherwise
		545	clears the exception object.
		546
		547	Coro will check for the exception each time a schedule-like-function
		548	returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down
		549	>>, C<< Coro::Handle->readable >> and so on. Most of these functions
		550	detect this case and return early in case an exception is pending.
		551
		552	The exception object will be thrown "as is" with the specified scalar in
		553	C<$@>, i.e. if it is a string, no line number or newline will be appended
		554	(unlike with C<die>).
		555
		556	This can be used as a softer means than C<cancel> to ask a coro to
		557	end itself, although there is no guarantee that the exception will lead to
		558	termination, and if the exception isn't caught it might well end the whole
		559	program.
		560
		561	You might also think of C<throw> as being the moral equivalent of
		562	C<kill>ing a coro with a signal (in this case, a scalar).
		563
394	=item $coroutine->join	564	=item $coro->join
395		565
396	Wait until the coroutine terminates and return any values given to the	566	Wait until the coro terminates and return any values given to the
397	C<terminate> or C<cancel> functions. C<join> can be called concurrently	567	C<terminate> or C<cancel> functions. C<join> can be called concurrently
398	from multiple coroutines.	568	from multiple coro, and all will be resumed and given the status
		569	return once the C<$coro> terminates.
399		570
400	=cut	571	=cut
401		572
402	sub join {	573	sub join {
403	my $self = shift;	574	my $self = shift;
…		…
414	}	585	}
415		586
416	wantarray ? @{$self->{_status}} : $self->{_status}[0];	587	wantarray ? @{$self->{_status}} : $self->{_status}[0];
417	}	588	}
418		589
419	=item $coroutine->on_destroy (\&cb)	590	=item $coro->on_destroy (\&cb)
420		591
421	Registers a callback that is called when this coroutine gets destroyed,	592	Registers a callback that is called when this coro gets destroyed,
422	but before it is joined. The callback gets passed the terminate arguments,	593	but before it is joined. The callback gets passed the terminate arguments,
423	if any.	594	if any, and I<must not> die, under any circumstances.
424		595
425	=cut	596	=cut
426		597
427	sub on_destroy {	598	sub on_destroy {
428	my ($self, $cb) = @_;	599	my ($self, $cb) = @_;
429		600
430	push @{ $self->{_on_destroy} }, $cb;	601	push @{ $self->{_on_destroy} }, $cb;
431	}	602	}
432		603
433	=item $oldprio = $coroutine->prio ($newprio)	604	=item $oldprio = $coro->prio ($newprio)
434		605
435	Sets (or gets, if the argument is missing) the priority of the	606	Sets (or gets, if the argument is missing) the priority of the
436	coroutine. Higher priority coroutines get run before lower priority	607	coro. Higher priority coro get run before lower priority
437	coroutines. Priorities are small signed integers (currently -4 .. +3),	608	coro. Priorities are small signed integers (currently -4 .. +3),
438	that you can refer to using PRIO_xxx constants (use the import tag :prio	609	that you can refer to using PRIO_xxx constants (use the import tag :prio
439	to get then):	610	to get then):
440		611
441	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN	612	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
442	3 > 1 > 0 > -1 > -3 > -4	613	3 > 1 > 0 > -1 > -3 > -4
443		614
444	# set priority to HIGH	615	# set priority to HIGH
445	current->prio(PRIO_HIGH);	616	current->prio (PRIO_HIGH);
446		617
447	The idle coroutine ($Coro::idle) always has a lower priority than any	618	The idle coro ($Coro::idle) always has a lower priority than any
448	existing coroutine.	619	existing coro.
449		620
450	Changing the priority of the current coroutine will take effect immediately,	621	Changing the priority of the current coro will take effect immediately,
451	but changing the priority of coroutines in the ready queue (but not	622	but changing the priority of coro in the ready queue (but not
452	running) will only take effect after the next schedule (of that	623	running) will only take effect after the next schedule (of that
453	coroutine). This is a bug that will be fixed in some future version.	624	coro). This is a bug that will be fixed in some future version.
454		625
455	=item $newprio = $coroutine->nice ($change)	626	=item $newprio = $coro->nice ($change)
456		627
457	Similar to C<prio>, but subtract the given value from the priority (i.e.	628	Similar to C<prio>, but subtract the given value from the priority (i.e.
458	higher values mean lower priority, just as in unix).	629	higher values mean lower priority, just as in unix).
459		630
460	=item $olddesc = $coroutine->desc ($newdesc)	631	=item $olddesc = $coro->desc ($newdesc)
461		632
462	Sets (or gets in case the argument is missing) the description for this	633	Sets (or gets in case the argument is missing) the description for this
463	coroutine. This is just a free-form string you can associate with a coroutine.	634	coro. This is just a free-form string you can associate with a
		635	coro.
464		636
465	This method simply sets the C<< $coroutine->{desc} >> member to the given string. You	637	This method simply sets the C<< $coro->{desc} >> member to the given
466	can modify this member directly if you wish.	638	string. You can modify this member directly if you wish.
467		639
468	=cut	640	=cut
469		641
470	sub desc {	642	sub desc {
471	my $old = $_[0]{desc};	643	my $old = $_[0]{desc};
472	$_[0]{desc} = $_[1] if @_ > 1;	644	$_[0]{desc} = $_[1] if @_ > 1;
473	$old;	645	$old;
474	}	646	}
475		647
		648	sub transfer {
		649	require Carp;
		650	Carp::croak ("You must not call ->transfer on Coro objects. Use Coro::State objects or the ->schedule_to method. Caught");
		651	}
		652
476	=back	653	=back
477		654
478	=head2 GLOBAL FUNCTIONS	655	=head1 GLOBAL FUNCTIONS
479		656
480	=over 4	657	=over 4
481		658
482	=item Coro::nready	659	=item Coro::nready
483		660
484	Returns the number of coroutines that are currently in the ready state,	661	Returns the number of coro that are currently in the ready state,
485	i.e. that can be switched to. The value C<0> means that the only runnable	662	i.e. that can be switched to by calling C<schedule> directory or
		663	indirectly. The value C<0> means that the only runnable coro is the
486	coroutine is the currently running one, so C<cede> would have no effect,	664	currently running one, so C<cede> would have no effect, and C<schedule>
487	and C<schedule> would cause a deadlock unless there is an idle handler	665	would cause a deadlock unless there is an idle handler that wakes up some
488	that wakes up some coroutines.	666	coro.
489		667
490	=item my $guard = Coro::guard { ... }	668	=item my $guard = Coro::guard { ... }
491		669
492	This creates and returns a guard object. Nothing happens until the object	670	This function still exists, but is deprecated. Please use the
493	gets destroyed, in which case the codeblock given as argument will be	671	C<Guard::guard> function instead.
494	executed. This is useful to free locks or other resources in case of a
495	runtime error or when the coroutine gets canceled, as in both cases the
496	guard block will be executed. The guard object supports only one method,
497	C<< ->cancel >>, which will keep the codeblock from being executed.
498		672
499	Example: set some flag and clear it again when the coroutine gets canceled
500	or the function returns:
501
502	sub do_something {
503	my $guard = Coro::guard { $busy = 0 };
504	$busy = 1;
505
506	# do something that requires $busy to be true
507	}
508
509	=cut	673	=cut
510		674
511	sub guard(&) {	675	BEGIN { *guard = \&Guard::guard }
512	bless \(my $cb = $_[0]), "Coro::guard"
513	}
514
515	sub Coro::guard::cancel {
516	${$_[0]} = sub { };
517	}
518
519	sub Coro::guard::DESTROY {
520	${$_[0]}->();
521	}
522
523		676
524	=item unblock_sub { ... }	677	=item unblock_sub { ... }
525		678
526	This utility function takes a BLOCK or code reference and "unblocks" it,	679	This utility function takes a BLOCK or code reference and "unblocks" it,
527	returning the new coderef. This means that the new coderef will return	680	returning a new coderef. Unblocking means that calling the new coderef
528	immediately without blocking, returning nothing, while the original code	681	will return immediately without blocking, returning nothing, while the
529	ref will be called (with parameters) from within its own coroutine.	682	original code ref will be called (with parameters) from within another
		683	coro.
530		684
531	The reason this function exists is that many event libraries (such as the	685	The reason this function exists is that many event libraries (such as the
532	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form	686	venerable L<Event\|Event> module) are not thread-safe (a weaker form
533	of thread-safety). This means you must not block within event callbacks,	687	of reentrancy). This means you must not block within event callbacks,
534	otherwise you might suffer from crashes or worse.	688	otherwise you might suffer from crashes or worse. The only event library
		689	currently known that is safe to use without C<unblock_sub> is L<EV>.
535		690
536	This function allows your callbacks to block by executing them in another	691	This function allows your callbacks to block by executing them in another
537	coroutine where it is safe to block. One example where blocking is handy	692	coro where it is safe to block. One example where blocking is handy
538	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to	693	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
539	disk.	694	disk, for example.
540		695
541	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when	696	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
542	creating event callbacks that want to block.	697	creating event callbacks that want to block.
		698
		699	If your handler does not plan to block (e.g. simply sends a message to
		700	another coro, or puts some other coro into the ready queue), there is
		701	no reason to use C<unblock_sub>.
		702
		703	Note that you also need to use C<unblock_sub> for any other callbacks that
		704	are indirectly executed by any C-based event loop. For example, when you
		705	use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it
		706	provides callbacks that are the result of some event callback, then you
		707	must not block either, or use C<unblock_sub>.
543		708
544	=cut	709	=cut
545		710
546	our @unblock_queue;	711	our @unblock_queue;
547		712
…		…
550	# return immediately and can be reused) and because we cannot cede	715	# return immediately and can be reused) and because we cannot cede
551	# inside an event callback.	716	# inside an event callback.
552	our $unblock_scheduler = new Coro sub {	717	our $unblock_scheduler = new Coro sub {
553	while () {	718	while () {
554	while (my $cb = pop @unblock_queue) {	719	while (my $cb = pop @unblock_queue) {
555	# this is an inlined copy of async_pool	720	&async_pool (@$cb);
556	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
557		721
558	$coro->{_invoke} = $cb;
559	$coro->ready;
560	cede; # for short-lived callbacks, this reduces pressure on the coro pool	722	# for short-lived callbacks, this reduces pressure on the coro pool
		723	# as the chance is very high that the async_poll coro will be back
		724	# in the idle state when cede returns
		725	cede;
561	}	726	}
562	schedule; # sleep well	727	schedule; # sleep well
563	}	728	}
564	};	729	};
565	$unblock_scheduler->desc ("[unblock_sub scheduler]");	730	$unblock_scheduler->{desc} = "[unblock_sub scheduler]";
566		731
567	sub unblock_sub(&) {	732	sub unblock_sub(&) {
568	my $cb = shift;	733	my $cb = shift;
569		734
570	sub {	735	sub {
571	unshift @unblock_queue, [$cb, @_];	736	unshift @unblock_queue, [$cb, @_];
572	$unblock_scheduler->ready;	737	$unblock_scheduler->ready;
573	}	738	}
574	}	739	}
575		740
		741	=item $cb = Coro::rouse_cb
		742
		743	Create and return a "rouse callback". That's a code reference that,
		744	when called, will remember a copy of its arguments and notify the owner
		745	coro of the callback.
		746
		747	See the next function.
		748
		749	=item @args = Coro::rouse_wait [$cb]
		750
		751	Wait for the specified rouse callback (or the last one that was created in
		752	this coro).
		753
		754	As soon as the callback is invoked (or when the callback was invoked
		755	before C<rouse_wait>), it will return the arguments originally passed to
		756	the rouse callback. In scalar context, that means you get the I<last>
		757	argument, just as if C<rouse_wait> had a C<return ($a1, $a2, $a3...)>
		758	statement at the end.
		759
		760	See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example.
		761
576	=back	762	=back
577		763
578	=cut	764	=cut
579		765
580	1;	766	1;
581		767
		768	=head1 HOW TO WAIT FOR A CALLBACK
		769
		770	It is very common for a coro to wait for some callback to be
		771	called. This occurs naturally when you use coro in an otherwise
		772	event-based program, or when you use event-based libraries.
		773
		774	These typically register a callback for some event, and call that callback
		775	when the event occured. In a coro, however, you typically want to
		776	just wait for the event, simplyifying things.
		777
		778	For example C<< AnyEvent->child >> registers a callback to be called when
		779	a specific child has exited:
		780
		781	my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... });
		782
		783	But from within a coro, you often just want to write this:
		784
		785	my $status = wait_for_child $pid;
		786
		787	Coro offers two functions specifically designed to make this easy,
		788	C<Coro::rouse_cb> and C<Coro::rouse_wait>.
		789
		790	The first function, C<rouse_cb>, generates and returns a callback that,
		791	when invoked, will save its arguments and notify the coro that
		792	created the callback.
		793
		794	The second function, C<rouse_wait>, waits for the callback to be called
		795	(by calling C<schedule> to go to sleep) and returns the arguments
		796	originally passed to the callback.
		797
		798	Using these functions, it becomes easy to write the C<wait_for_child>
		799	function mentioned above:
		800
		801	sub wait_for_child($) {
		802	my ($pid) = @_;
		803
		804	my $watcher = AnyEvent->child (pid => $pid, cb => Coro::rouse_cb);
		805
		806	my ($rpid, $rstatus) = Coro::rouse_wait;
		807	$rstatus
		808	}
		809
		810	In the case where C<rouse_cb> and C<rouse_wait> are not flexible enough,
		811	you can roll your own, using C<schedule>:
		812
		813	sub wait_for_child($) {
		814	my ($pid) = @_;
		815
		816	# store the current coro in $current,
		817	# and provide result variables for the closure passed to ->child
		818	my $current = $Coro::current;
		819	my ($done, $rstatus);
		820
		821	# pass a closure to ->child
		822	my $watcher = AnyEvent->child (pid => $pid, cb => sub {
		823	$rstatus = $_[1]; # remember rstatus
		824	$done = 1; # mark $rstatus as valud
		825	});
		826
		827	# wait until the closure has been called
		828	schedule while !$done;
		829
		830	$rstatus
		831	}
		832
		833
582	=head1 BUGS/LIMITATIONS	834	=head1 BUGS/LIMITATIONS
583		835
584	- you must make very sure that no coro is still active on global	836	=over 4
585	destruction. very bad things might happen otherwise (usually segfaults).
586		837
		838	=item fork with pthread backend
		839
		840	When Coro is compiled using the pthread backend (which isn't recommended
		841	but required on many BSDs as their libcs are completely broken), then
		842	coro will not survive a fork. There is no known workaround except to
		843	fix your libc and use a saner backend.
		844
		845	=item perl process emulation ("threads")
		846
587	- this module is not thread-safe. You should only ever use this module	847	This module is not perl-pseudo-thread-safe. You should only ever use this
588	from the same thread (this requirement might be loosened in the future	848	module from the first thread (this requirement might be removed in the
589	to allow per-thread schedulers, but Coro::State does not yet allow	849	future to allow per-thread schedulers, but Coro::State does not yet allow
590	this).	850	this). I recommend disabling thread support and using processes, as having
		851	the windows process emulation enabled under unix roughly halves perl
		852	performance, even when not used.
		853
		854	=item coro switching is not signal safe
		855
		856	You must not switch to another coro from within a signal handler
		857	(only relevant with %SIG - most event libraries provide safe signals).
		858
		859	That means you I<MUST NOT> call any function that might "block" the
		860	current coro - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or
		861	anything that calls those. Everything else, including calling C<ready>,
		862	works.
		863
		864	=back
		865
591		866
592	=head1 SEE ALSO	867	=head1 SEE ALSO
593		868
		869	Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
		870
		871	Debugging: L<Coro::Debug>.
		872
594	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.	873	Support/Utility: L<Coro::Specific>, L<Coro::Util>.
595		874
596	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.	875	Locking and IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>,
		876	L<Coro::SemaphoreSet>, L<Coro::RWLock>.
597		877
598	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.	878	I/O and Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>.
599		879
600	Embedding: L<Coro:MakeMaker>	880	Compatibility with other modules: L<Coro::LWP> (but see also L<AnyEvent::HTTP> for
		881	a better-working alternative), L<Coro::BDB>, L<Coro::Storable>,
		882	L<Coro::Select>.
		883
		884	XS API: L<Coro::MakeMaker>.
		885
		886	Low level Configuration, Thread Environment, Continuations: L<Coro::State>.
601		887
602	=head1 AUTHOR	888	=head1 AUTHOR
603		889
604	Marc Lehmann <schmorp@schmorp.de>	890	Marc Lehmann <schmorp@schmorp.de>
605	http://home.schmorp.de/	891	http://home.schmorp.de/

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Comparing Coro/Coro.pm (file contents): Revision 1.144 by root, Wed Oct 3 01:48:05 2007 UTC vs. Revision 1.258 by root, Fri Jun 26 14:25:45 2009 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.144 by root, Wed Oct 3 01:48:05 2007 UTC vs.
Revision 1.258 by root, Fri Jun 26 14:25:45 2009 UTC