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

Comparing Coro/Coro.pm (file contents):
Revision 1.178 by root, Thu Apr 17 22:33:10 2008 UTC vs.
Revision 1.229 by root, Thu Nov 20 06:32:55 2008 UTC

…		…
2		2
3	Coro - coroutine process abstraction	3	Coro - coroutine process abstraction
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";	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 coroutine
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	This module collection manages coroutines. Coroutines are similar to
31	to threads but don't run in parallel at the same time even on SMP	32	threads but don't (in general) run in parallel at the same time even
32	machines. The specific flavor of coroutine used in this module also	33	on SMP machines. The specific flavor of coroutine used in this module
33	guarantees you that it will not switch between coroutines unless	34	also guarantees you that it will not switch between coroutines unless
34	necessary, at easily-identified points in your program, so locking and	35	necessary, at easily-identified points in your program, so locking and
35	parallel access are rarely an issue, making coroutine programming much	36	parallel access are rarely an issue, making coroutine programming much
36	safer than threads programming.	37	safer and easier than threads programming.
37		38
38	(Perl, however, does not natively support real threads but instead does a	39	Unlike a normal perl program, however, coroutines allow you to have
39	very slow and memory-intensive emulation of processes using threads. This	40	multiple running interpreters that share data, which is especially useful
40	is a performance win on Windows machines, and a loss everywhere else).	41	to code pseudo-parallel processes and for event-based programming, such as
		42	multiple HTTP-GET requests running concurrently. See L<Coro::AnyEvent> to
		43	learn more.
		44
		45	Coroutines are also useful because Perl has no support for threads (the so
		46	called "threads" that perl offers are nothing more than the (bad) process
		47	emulation coming from the Windows platform: On standard operating systems
		48	they serve no purpose whatsoever, except by making your programs slow and
		49	making them use a lot of memory. Best disable them when building perl, or
		50	aks your software vendor/distributor to do it for you).
41		51
42	In this module, coroutines are defined as "callchain + lexical variables +	52	In this module, coroutines are defined as "callchain + lexical variables +
43	@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,	53	@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,
44	its own set of lexicals and its own set of perls most important global	54	its own set of lexicals and its own set of perls most important global
45	variables (see L<Coro::State> for more configuration).	55	variables (see L<Coro::State> for more configuration).
46		56
47	=cut	57	=cut
48		58
49	package Coro;	59	package Coro;
50		60
51	use strict;	61	use strict qw(vars subs);
52	no warnings "uninitialized";	62	no warnings "uninitialized";
53		63
54	use Coro::State;	64	use Coro::State;
55		65
56	use base qw(Coro::State Exporter);	66	use base qw(Coro::State Exporter);
57		67
58	our $idle; # idle handler	68	our $idle; # idle handler
59	our $main; # main coroutine	69	our $main; # main coroutine
60	our $current; # current coroutine	70	our $current; # current coroutine
61		71
62	our $VERSION = '4.51';	72	our $VERSION = 5.0;
63		73
64	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);	74	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
65	our %EXPORT_TAGS = (	75	our %EXPORT_TAGS = (
66	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	76	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
67	);	77	);
68	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));	78	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
69		79
70	{
71	my @async;
72	my $init;
73
74	# this way of handling attributes simply is NOT scalable ;()
75	sub import {
76	no strict 'refs';
77
78	Coro->export_to_level (1, @_);
79
80	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
81	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
82	my ($package, $ref) = (shift, shift);
83	my @attrs;
84	for (@_) {
85	if ($_ eq "Coro") {
86	push @async, $ref;
87	unless ($init++) {
88	eval q{
89	sub INIT {
90	&async(pop @async) while @async;
91	}
92	};
93	}
94	} else {
95	push @attrs, $_;
96	}
97	}
98	return $old ? $old->($package, $ref, @attrs) : @attrs;
99	};
100	}
101
102	}
103
104	=over 4	80	=over 4
105		81
106	=item $main	82	=item $Coro::main
107		83
108	This coroutine represents the main program.	84	This variable stores the coroutine object that represents the main
		85	program. While you cna C<ready> it and do most other things you can do to
		86	coroutines, it is mainly useful to compare again C<$Coro::current>, to see
		87	whether you are running in the main program or not.
109		88
110	=cut	89	=cut
111		90
112	$main = new Coro;	91	# $main is now being initialised by Coro::State
113		92
114	=item $current (or as function: current)	93	=item $Coro::current
115		94
116	The current coroutine (the last coroutine switched to). The initial value	95	The coroutine object representing the current coroutine (the last
		96	coroutine that the Coro scheduler switched to). The initial value is
117	is C<$main> (of course).	97	C<$Coro::main> (of course).
118		98
119	This variable is B<strictly> I<read-only>. It is provided for performance	99	This variable is B<strictly> I<read-only>. You can take copies of the
120	reasons. If performance is not essential you are encouraged to use the	100	value stored in it and use it as any other coroutine object, but you must
121	C<Coro::current> function instead.	101	not otherwise modify the variable itself.
122		102
123	=cut	103	=cut
124		104
125	$main->{desc} = "[main::]";
126
127	# maybe some other module used Coro::Specific before...
128	$main->{_specific} = $current->{_specific}
129	if $current;
130
131	_set_current $main;
132
133	sub current() { $current }	105	sub current() { $current } # [DEPRECATED]
134		106
135	=item $idle	107	=item $Coro::idle
136		108
137	A callback that is called whenever the scheduler finds no ready coroutines	109	This variable is mainly useful to integrate Coro into event loops. It is
138	to run. The default implementation prints "FATAL: deadlock detected" and	110	usually better to rely on L<Coro::AnyEvent> or LC<Coro::EV>, as this is
139	exits, because the program has no other way to continue.	111	pretty low-level functionality.
		112
		113	This variable stores a callback that is called whenever the scheduler
		114	finds no ready coroutines to run. The default implementation prints
		115	"FATAL: deadlock detected" and exits, because the program has no other way
		116	to continue.
140		117
141	This hook is overwritten by modules such as C<Coro::Timer> and	118	This hook is overwritten by modules such as C<Coro::Timer> and
142	C<Coro::Event> to wait on an external event that hopefully wake up a	119	C<Coro::AnyEvent> to wait on an external event that hopefully wake up a
143	coroutine so the scheduler can run it.	120	coroutine so the scheduler can run it.
		121
		122	Note that the callback I<must not>, under any circumstances, block
		123	the current coroutine. Normally, this is achieved by having an "idle
		124	coroutine" that calls the event loop and then blocks again, and then
		125	readying that coroutine in the idle handler.
		126
		127	See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this
		128	technique.
144		129
145	Please note that if your callback recursively invokes perl (e.g. for event	130	Please note that if your callback recursively invokes perl (e.g. for event
146	handlers), then it must be prepared to be called recursively itself.	131	handlers), then it must be prepared to be called recursively itself.
147		132
148	=cut	133	=cut
…		…
159	$self->_destroy	144	$self->_destroy
160	or return;	145	or return;
161		146
162	# call all destruction callbacks	147	# call all destruction callbacks
163	$_->(@{$self->{_status}})	148	$_->(@{$self->{_status}})
164	for @{(delete $self->{_on_destroy}) \|\| []};	149	for @{ delete $self->{_on_destroy} \|\| [] };
165	}	150	}
166		151
167	# this coroutine is necessary because a coroutine	152	# this coroutine is necessary because a coroutine
168	# cannot destroy itself.	153	# cannot destroy itself.
169	my @destroy;	154	our @destroy;
170	my $manager;	155	our $manager;
171		156
172	$manager = new Coro sub {	157	$manager = new Coro sub {
173	while () {	158	while () {
174	(shift @destroy)->_cancel	159	(shift @destroy)->_cancel
175	while @destroy;	160	while @destroy;
176		161
177	&schedule;	162	&schedule;
178	}	163	}
179	};	164	};
180	$manager->desc ("[coro manager]");	165	$manager->{desc} = "[coro manager]";
181	$manager->prio (PRIO_MAX);	166	$manager->prio (PRIO_MAX);
182		167
183	=back	168	=back
184		169
185	=head2 STATIC METHODS	170	=head2 SIMPLE COROUTINE CREATION
186
187	Static methods are actually functions that operate on the current coroutine only.
188		171
189	=over 4	172	=over 4
190		173
191	=item async { ... } [@args...]	174	=item async { ... } [@args...]
192		175
193	Create a new asynchronous coroutine and return it's coroutine object	176	Create a new coroutine and return it's coroutine object (usually
194	(usually unused). When the sub returns the new coroutine is automatically	177	unused). The coroutine will be put into the ready queue, so
		178	it will start running automatically on the next scheduler run.
		179
		180	The first argument is a codeblock/closure that should be executed in the
		181	coroutine. When it returns argument returns the coroutine is automatically
195	terminated.	182	terminated.
196		183
		184	The remaining arguments are passed as arguments to the closure.
		185
197	See the C<Coro::State::new> constructor for info about the coroutine	186	See the C<Coro::State::new> constructor for info about the coroutine
198	environment in which coroutines run.	187	environment in which coroutines are executed.
199		188
200	Calling C<exit> in a coroutine will do the same as calling exit outside	189	Calling C<exit> in a coroutine will do the same as calling exit outside
201	the coroutine. Likewise, when the coroutine dies, the program will exit,	190	the coroutine. Likewise, when the coroutine dies, the program will exit,
202	just as it would in the main program.	191	just as it would in the main program.
203		192
		193	If you do not want that, you can provide a default C<die> handler, or
		194	simply avoid dieing (by use of C<eval>).
		195
204	# create a new coroutine that just prints its arguments	196	Example: Create a new coroutine that just prints its arguments.
		197
205	async {	198	async {
206	print "@_\n";	199	print "@_\n";
207	} 1,2,3,4;	200	} 1,2,3,4;
208		201
209	=cut	202	=cut
…		…
215	}	208	}
216		209
217	=item async_pool { ... } [@args...]	210	=item async_pool { ... } [@args...]
218		211
219	Similar to C<async>, but uses a coroutine pool, so you should not call	212	Similar to C<async>, but uses a coroutine pool, so you should not call
220	terminate or join (although you are allowed to), and you get a coroutine	213	terminate or join on it (although you are allowed to), and you get a
221	that might have executed other code already (which can be good or bad :).	214	coroutine that might have executed other code already (which can be good
		215	or bad :).
222		216
		217	On the plus side, this function is about twice as fast as creating (and
		218	destroying) a completely new coroutine, so if you need a lot of generic
		219	coroutines in quick successsion, use C<async_pool>, not C<async>.
		220
223	Also, the block is executed in an C<eval> context and a warning will be	221	The code block is executed in an C<eval> context and a warning will be
224	issued in case of an exception instead of terminating the program, as	222	issued in case of an exception instead of terminating the program, as
225	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>	223	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
226	will not work in the expected way, unless you call terminate or cancel,	224	will not work in the expected way, unless you call terminate or cancel,
227	which somehow defeats the purpose of pooling.	225	which somehow defeats the purpose of pooling (but is fine in the
		226	exceptional case).
228		227
229	The priority will be reset to C<0> after each job, tracing will be	228	The priority will be reset to C<0> after each run, tracing will be
230	disabled, the description will be reset and the default output filehandle	229	disabled, the description will be reset and the default output filehandle
231	gets restored, so you can change alkl these. Otherwise the coroutine will	230	gets restored, so you can change all these. Otherwise the coroutine will
232	be re-used "as-is": most notably if you change other per-coroutine global	231	be re-used "as-is": most notably if you change other per-coroutine global
233	stuff such as C<$/> you need to revert that change, which is most simply	232	stuff such as C<$/> you I<must needs> revert that change, which is most
234	done by using local as in C< local $/ >.	233	simply done by using local as in: C<< local $/ >>.
235		234
236	The pool size is limited to 8 idle coroutines (this can be adjusted by	235	The idle pool size is limited to C<8> idle coroutines (this can be
237	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as	236	adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle
238	required.	237	coros as required.
239		238
240	If you are concerned about pooled coroutines growing a lot because a	239	If you are concerned about pooled coroutines growing a lot because a
241	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool	240	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
242	{ terminate }> once per second or so to slowly replenish the pool. In	241	{ terminate }> once per second or so to slowly replenish the pool. In
243	addition to that, when the stacks used by a handler grows larger than 16kb	242	addition to that, when the stacks used by a handler grows larger than 16kb
244	(adjustable with $Coro::POOL_RSS) it will also exit.	243	(adjustable via $Coro::POOL_RSS) it will also be destroyed.
245		244
246	=cut	245	=cut
247		246
248	our $POOL_SIZE = 8;	247	our $POOL_SIZE = 8;
249	our $POOL_RSS = 16 * 1024;	248	our $POOL_RSS = 16 * 1024;
250	our @async_pool;	249	our @async_pool;
251		250
252	sub pool_handler {	251	sub pool_handler {
253	my $cb;
254
255	while () {	252	while () {
256	eval {	253	eval {
257	while () {	254	&{&_pool_handler} while 1;
258	_pool_1 $cb;
259	&$cb;
260	_pool_2 $cb;
261	&schedule;
262	}
263	};	255	};
264		256
265	last if $@ eq "\3async_pool terminate\2\n";
266	warn $@ if $@;	257	warn $@ if $@;
267	}	258	}
268	}	259	}
269		260
270	sub async_pool(&@) {	261	=back
271	# this is also inlined into the unlock_scheduler
272	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
273		262
274	$coro->{_invoke} = [@_];	263	=head2 STATIC METHODS
275	$coro->ready;
276		264
277	$coro	265	Static methods are actually functions that operate on the current coroutine.
278	}	266
		267	=over 4
279		268
280	=item schedule	269	=item schedule
281		270
282	Calls the scheduler. Please note that the current coroutine will not be put	271	Calls the scheduler. The scheduler will find the next coroutine that is
		272	to be run from the ready queue and switches to it. The next coroutine
		273	to be run is simply the one with the highest priority that is longest
		274	in its ready queue. If there is no coroutine ready, it will clal the
		275	C<$Coro::idle> hook.
		276
		277	Please note that the current coroutine will I<not> be put into the ready
283	into the ready queue, so calling this function usually means you will	278	queue, so calling this function usually means you will never be called
284	never be called again unless something else (e.g. an event handler) calls	279	again unless something else (e.g. an event handler) calls C<< ->ready >>,
285	ready.	280	thus waking you up.
286		281
287	The canonical way to wait on external events is this:	282	This makes C<schedule> I<the> generic method to use to block the current
		283	coroutine and wait for events: first you remember the current coroutine in
		284	a variable, then arrange for some callback of yours to call C<< ->ready
		285	>> on that once some event happens, and last you call C<schedule> to put
		286	yourself to sleep. Note that a lot of things can wake your coroutine up,
		287	so you need to check whether the event indeed happened, e.g. by storing the
		288	status in a variable.
288		289
289	{	290	See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks.
290	# remember current coroutine
291	my $current = $Coro::current;
292
293	# register a hypothetical event handler
294	on_event_invoke sub {
295	# wake up sleeping coroutine
296	$current->ready;
297	undef $current;
298	};
299
300	# call schedule until event occurred.
301	# in case we are woken up for other reasons
302	# (current still defined), loop.
303	Coro::schedule while $current;
304	}
305		291
306	=item cede	292	=item cede
307		293
308	"Cede" to other coroutines. This function puts the current coroutine into the	294	"Cede" to other coroutines. This function puts the current coroutine into
309	ready queue and calls C<schedule>, which has the effect of giving up the	295	the ready queue and calls C<schedule>, which has the effect of giving
310	current "timeslice" to other coroutines of the same or higher priority.	296	up the current "timeslice" to other coroutines of the same or higher
		297	priority. Once your coroutine gets its turn again it will automatically be
		298	resumed.
		299
		300	This function is often called C<yield> in other languages.
311		301
312	=item Coro::cede_notself	302	=item Coro::cede_notself
313		303
314	Works like cede, but is not exported by default and will cede to any	304	Works like cede, but is not exported by default and will cede to I<any>
315	coroutine, regardless of priority, once.	305	coroutine, regardless of priority. This is useful sometimes to ensure
		306	progress is made.
316		307
317	=item terminate [arg...]	308	=item terminate [arg...]
318		309
319	Terminates the current coroutine with the given status values (see L<cancel>).	310	Terminates the current coroutine with the given status values (see L<cancel>).
320		311
…		…
322		313
323	Kills/terminates/cancels all coroutines except the currently running	314	Kills/terminates/cancels all coroutines except the currently running
324	one. This is useful after a fork, either in the child or the parent, as	315	one. This is useful after a fork, either in the child or the parent, as
325	usually only one of them should inherit the running coroutines.	316	usually only one of them should inherit the running coroutines.
326		317
		318	Note that while this will try to free some of the main programs resources,
		319	you cannot free all of them, so if a coroutine that is not the main
		320	program calls this function, there will be some one-time resource leak.
		321
327	=cut	322	=cut
328		323
329	sub terminate {	324	sub terminate {
330	$current->cancel (@_);	325	$current->{_status} = [@_];
		326	push @destroy, $current;
		327	$manager->ready;
		328	do { &schedule } while 1;
331	}	329	}
332		330
333	sub killall {	331	sub killall {
334	for (Coro::State::list) {	332	for (Coro::State::list) {
335	$_->cancel	333	$_->cancel
…		…
339		337
340	=back	338	=back
341		339
342	=head2 COROUTINE METHODS	340	=head2 COROUTINE METHODS
343		341
344	These are the methods you can call on coroutine objects.	342	These are the methods you can call on coroutine objects (or to create
		343	them).
345		344
346	=over 4	345	=over 4
347		346
348	=item new Coro \&sub [, @args...]	347	=item new Coro \&sub [, @args...]
349		348
350	Create a new coroutine and return it. When the sub returns the coroutine	349	Create a new coroutine and return it. When the sub returns, the coroutine
351	automatically terminates as if C<terminate> with the returned values were	350	automatically terminates as if C<terminate> with the returned values were
352	called. To make the coroutine run you must first put it into the ready queue	351	called. To make the coroutine run you must first put it into the ready
353	by calling the ready method.	352	queue by calling the ready method.
354		353
355	See C<async> and C<Coro::State::new> for additional info about the	354	See C<async> and C<Coro::State::new> for additional info about the
356	coroutine environment.	355	coroutine environment.
357		356
358	=cut	357	=cut
359		358
360	sub _run_coro {	359	sub _terminate {
361	terminate &{+shift};	360	terminate &{+shift};
362	}	361	}
363		362
364	sub new {
365	my $class = shift;
366
367	$class->SUPER::new (\&_run_coro, @_)
368	}
369
370	=item $success = $coroutine->ready	363	=item $success = $coroutine->ready
371		364
372	Put the given coroutine into the ready queue (according to it's priority)	365	Put the given coroutine into the end of its ready queue (there is one
373	and return true. If the coroutine is already in the ready queue, do nothing	366	queue for each priority) and return true. If the coroutine is already in
374	and return false.	367	the ready queue, do nothing and return false.
		368
		369	This ensures that the scheduler will resume this coroutine automatically
		370	once all the coroutines of higher priority and all coroutines of the same
		371	priority that were put into the ready queue earlier have been resumed.
375		372
376	=item $is_ready = $coroutine->is_ready	373	=item $is_ready = $coroutine->is_ready
377		374
378	Return wether the coroutine is currently the ready queue or not,	375	Return whether the coroutine is currently the ready queue or not,
379		376
380	=item $coroutine->cancel (arg...)	377	=item $coroutine->cancel (arg...)
381		378
382	Terminates the given coroutine and makes it return the given arguments as	379	Terminates the given coroutine and makes it return the given arguments as
383	status (default: the empty list). Never returns if the coroutine is the	380	status (default: the empty list). Never returns if the coroutine is the
…		…
385		382
386	=cut	383	=cut
387		384
388	sub cancel {	385	sub cancel {
389	my $self = shift;	386	my $self = shift;
390	$self->{_status} = [@_];
391		387
392	if ($current == $self) {	388	if ($current == $self) {
393	push @destroy, $self;	389	terminate @_;
394	$manager->ready;
395	&schedule while 1;
396	} else {	390	} else {
		391	$self->{_status} = [@_];
397	$self->_cancel;	392	$self->_cancel;
398	}	393	}
399	}	394	}
		395
		396	=item $coroutine->schedule_to
		397
		398	Puts the current coroutine to sleep (like C<Coro::schedule>), but instead
		399	of continuing with the next coro from the ready queue, always switch to
		400	the given coroutine object (regardless of priority etc.). The readyness
		401	state of that coroutine isn't changed.
		402
		403	This is an advanced method for special cases - I'd love to hear about any
		404	uses for this one.
		405
		406	=item $coroutine->cede_to
		407
		408	Like C<schedule_to>, but puts the current coroutine into the ready
		409	queue. This has the effect of temporarily switching to the given
		410	coroutine, and continuing some time later.
		411
		412	This is an advanced method for special cases - I'd love to hear about any
		413	uses for this one.
		414
		415	=item $coroutine->throw ([$scalar])
		416
		417	If C<$throw> is specified and defined, it will be thrown as an exception
		418	inside the coroutine at the next convenient point in time. Otherwise
		419	clears the exception object.
		420
		421	Coro will check for the exception each time a schedule-like-function
		422	returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down
		423	>>, C<< Coro::Handle->readable >> and so on. Most of these functions
		424	detect this case and return early in case an exception is pending.
		425
		426	The exception object will be thrown "as is" with the specified scalar in
		427	C<$@>, i.e. if it is a string, no line number or newline will be appended
		428	(unlike with C<die>).
		429
		430	This can be used as a softer means than C<cancel> to ask a coroutine to
		431	end itself, although there is no guarantee that the exception will lead to
		432	termination, and if the exception isn't caught it might well end the whole
		433	program.
		434
		435	You might also think of C<throw> as being the moral equivalent of
		436	C<kill>ing a coroutine with a signal (in this case, a scalar).
400		437
401	=item $coroutine->join	438	=item $coroutine->join
402		439
403	Wait until the coroutine terminates and return any values given to the	440	Wait until the coroutine terminates and return any values given to the
404	C<terminate> or C<cancel> functions. C<join> can be called concurrently	441	C<terminate> or C<cancel> functions. C<join> can be called concurrently
405	from multiple coroutines.	442	from multiple coroutines, and all will be resumed and given the status
		443	return once the C<$coroutine> terminates.
406		444
407	=cut	445	=cut
408		446
409	sub join {	447	sub join {
410	my $self = shift;	448	my $self = shift;
…		…
425		463
426	=item $coroutine->on_destroy (\&cb)	464	=item $coroutine->on_destroy (\&cb)
427		465
428	Registers a callback that is called when this coroutine gets destroyed,	466	Registers a callback that is called when this coroutine gets destroyed,
429	but before it is joined. The callback gets passed the terminate arguments,	467	but before it is joined. The callback gets passed the terminate arguments,
430	if any.	468	if any, and I<must not> die, under any circumstances.
431		469
432	=cut	470	=cut
433		471
434	sub on_destroy {	472	sub on_destroy {
435	my ($self, $cb) = @_;	473	my ($self, $cb) = @_;
…		…
465	higher values mean lower priority, just as in unix).	503	higher values mean lower priority, just as in unix).
466		504
467	=item $olddesc = $coroutine->desc ($newdesc)	505	=item $olddesc = $coroutine->desc ($newdesc)
468		506
469	Sets (or gets in case the argument is missing) the description for this	507	Sets (or gets in case the argument is missing) the description for this
470	coroutine. This is just a free-form string you can associate with a coroutine.	508	coroutine. This is just a free-form string you can associate with a
		509	coroutine.
471		510
472	This method simply sets the C<< $coroutine->{desc} >> member to the given string. You	511	This method simply sets the C<< $coroutine->{desc} >> member to the given
473	can modify this member directly if you wish.	512	string. You can modify this member directly if you wish.
474
475	=item $coroutine->throw ([$scalar])
476
477	If C<$throw> is specified and defined, it will be thrown as an exception
478	inside the coroutine at the next convinient point in time (usually after
479	it gains control at the next schedule/transfer/cede). Otherwise clears the
480	exception object.
481
482	The exception object will be thrown "as is" with the specified scalar in
483	C<$@>, i.e. if it is a string, no line number or newline will be appended
484	(unlike with C<die>).
485
486	This can be used as a softer means than C<cancel> to ask a coroutine to
487	end itself, although there is no guarentee that the exception will lead to
488	termination, and if the exception isn't caught it might well end the whole
489	program.
490		513
491	=cut	514	=cut
492		515
493	sub desc {	516	sub desc {
494	my $old = $_[0]{desc};	517	my $old = $_[0]{desc};
…		…
503	=over 4	526	=over 4
504		527
505	=item Coro::nready	528	=item Coro::nready
506		529
507	Returns the number of coroutines that are currently in the ready state,	530	Returns the number of coroutines that are currently in the ready state,
508	i.e. that can be switched to. The value C<0> means that the only runnable	531	i.e. that can be switched to by calling C<schedule> directory or
		532	indirectly. The value C<0> means that the only runnable coroutine is the
509	coroutine is the currently running one, so C<cede> would have no effect,	533	currently running one, so C<cede> would have no effect, and C<schedule>
510	and C<schedule> would cause a deadlock unless there is an idle handler	534	would cause a deadlock unless there is an idle handler that wakes up some
511	that wakes up some coroutines.	535	coroutines.
512		536
513	=item my $guard = Coro::guard { ... }	537	=item my $guard = Coro::guard { ... }
514		538
515	This creates and returns a guard object. Nothing happens until the object	539	This creates and returns a guard object. Nothing happens until the object
516	gets destroyed, in which case the codeblock given as argument will be	540	gets destroyed, in which case the codeblock given as argument will be
…		…
545		569
546		570
547	=item unblock_sub { ... }	571	=item unblock_sub { ... }
548		572
549	This utility function takes a BLOCK or code reference and "unblocks" it,	573	This utility function takes a BLOCK or code reference and "unblocks" it,
550	returning the new coderef. This means that the new coderef will return	574	returning a new coderef. Unblocking means that calling the new coderef
551	immediately without blocking, returning nothing, while the original code	575	will return immediately without blocking, returning nothing, while the
552	ref will be called (with parameters) from within its own coroutine.	576	original code ref will be called (with parameters) from within another
		577	coroutine.
553		578
554	The reason this function exists is that many event libraries (such as the	579	The reason this function exists is that many event libraries (such as the
555	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form	580	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
556	of thread-safety). This means you must not block within event callbacks,	581	of thread-safety). This means you must not block within event callbacks,
557	otherwise you might suffer from crashes or worse.	582	otherwise you might suffer from crashes or worse. The only event library
		583	currently known that is safe to use without C<unblock_sub> is L<EV>.
558		584
559	This function allows your callbacks to block by executing them in another	585	This function allows your callbacks to block by executing them in another
560	coroutine where it is safe to block. One example where blocking is handy	586	coroutine where it is safe to block. One example where blocking is handy
561	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to	587	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
562	disk.	588	disk, for example.
563		589
564	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when	590	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
565	creating event callbacks that want to block.	591	creating event callbacks that want to block.
		592
		593	If your handler does not plan to block (e.g. simply sends a message to
		594	another coroutine, or puts some other coroutine into the ready queue),
		595	there is no reason to use C<unblock_sub>.
		596
		597	Note that you also need to use C<unblock_sub> for any other callbacks that
		598	are indirectly executed by any C-based event loop. For example, when you
		599	use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it
		600	provides callbacks that are the result of some event callback, then you
		601	must not block either, or use C<unblock_sub>.
566		602
567	=cut	603	=cut
568		604
569	our @unblock_queue;	605	our @unblock_queue;
570		606
…		…
573	# return immediately and can be reused) and because we cannot cede	609	# return immediately and can be reused) and because we cannot cede
574	# inside an event callback.	610	# inside an event callback.
575	our $unblock_scheduler = new Coro sub {	611	our $unblock_scheduler = new Coro sub {
576	while () {	612	while () {
577	while (my $cb = pop @unblock_queue) {	613	while (my $cb = pop @unblock_queue) {
578	# this is an inlined copy of async_pool	614	&async_pool (@$cb);
579	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
580		615
581	$coro->{_invoke} = $cb;
582	$coro->ready;
583	cede; # for short-lived callbacks, this reduces pressure on the coro pool	616	# for short-lived callbacks, this reduces pressure on the coro pool
		617	# as the chance is very high that the async_poll coro will be back
		618	# in the idle state when cede returns
		619	cede;
584	}	620	}
585	schedule; # sleep well	621	schedule; # sleep well
586	}	622	}
587	};	623	};
588	$unblock_scheduler->desc ("[unblock_sub scheduler]");	624	$unblock_scheduler->{desc} = "[unblock_sub scheduler]";
589		625
590	sub unblock_sub(&) {	626	sub unblock_sub(&) {
591	my $cb = shift;	627	my $cb = shift;
592		628
593	sub {	629	sub {
594	unshift @unblock_queue, [$cb, @_];	630	unshift @unblock_queue, [$cb, @_];
595	$unblock_scheduler->ready;	631	$unblock_scheduler->ready;
596	}	632	}
597	}	633	}
598		634
		635	=item $cb = Coro::rouse_cb
		636
		637	Create and return a "rouse callback". That's a code reference that, when
		638	called, will save its arguments and notify the owner coroutine of the
		639	callback.
		640
		641	See the next function.
		642
		643	=item @args = Coro::rouse_wait [$cb]
		644
		645	Wait for the specified rouse callback (or the last one tht was created in
		646	this coroutine).
		647
		648	As soon as the callback is invoked (or when the calback was invoked before
		649	C<rouse_wait>), it will return a copy of the arguments originally passed
		650	to the rouse callback.
		651
		652	See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example.
		653
599	=back	654	=back
600		655
601	=cut	656	=cut
602		657
603	1;	658	1;
604		659
		660	=head1 HOW TO WAIT FOR A CALLBACK
		661
		662	It is very common for a coroutine to wait for some callback to be
		663	called. This occurs naturally when you use coroutines in an otherwise
		664	event-based program, or when you use event-based libraries.
		665
		666	These typically register a callback for some event, and call that callback
		667	when the event occured. In a coroutine, however, you typically want to
		668	just wait for the event, simplyifying things.
		669
		670	For example C<< AnyEvent->child >> registers a callback to be called when
		671	a specific child has exited:
		672
		673	my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... });
		674
		675	But from withina coroutine, you often just want to write this:
		676
		677	my $status = wait_for_child $pid;
		678
		679	Coro offers two functions specifically designed to make this easy,
		680	C<Coro::rouse_cb> and C<Coro::rouse_wait>.
		681
		682	The first function, C<rouse_cb>, generates and returns a callback that,
		683	when invoked, will save it's arguments and notify the coroutine that
		684	created the callback.
		685
		686	The second function, C<rouse_wait>, waits for the callback to be called
		687	(by calling C<schedule> to go to sleep) and returns the arguments
		688	originally passed to the callback.
		689
		690	Using these functions, it becomes easy to write the C<wait_for_child>
		691	function mentioned above:
		692
		693	sub wait_for_child($) {
		694	my ($pid) = @_;
		695
		696	my $watcher = AnyEvent->child (pid => $pid, cb => Coro::rouse_cb);
		697
		698	my ($rpid, $rstatus) = Coro::rouse_wait;
		699	$rstatus
		700	}
		701
		702	In the case where C<rouse_cb> and C<rouse_wait> are not flexible enough,
		703	you can roll your own, using C<schedule>:
		704
		705	sub wait_for_child($) {
		706	my ($pid) = @_;
		707
		708	# store the current coroutine in $current,
		709	# and provide result variables for the closure passed to ->child
		710	my $current = $Coro::current;
		711	my ($done, $rstatus);
		712
		713	# pass a closure to ->child
		714	my $watcher = AnyEvent->child (pid => $pid, cb => sub {
		715	$rstatus = $_[1]; # remember rstatus
		716	$done = 1; # mark $rstatus as valud
		717	});
		718
		719	# wait until the closure has been called
		720	schedule while !$done;
		721
		722	$rstatus
		723	}
		724
		725
605	=head1 BUGS/LIMITATIONS	726	=head1 BUGS/LIMITATIONS
606		727
607	- you must make very sure that no coro is still active on global	728	=over 4
608	destruction. very bad things might happen otherwise (usually segfaults).
609		729
		730	=item fork with pthread backend
		731
		732	When Coro is compiled using the pthread backend (which isn't recommended
		733	but required on many BSDs as their libcs are completely broken), then
		734	coroutines will not survive a fork. There is no known workaround except to
		735	fix your libc and use a saner backend.
		736
		737	=item perl process emulation ("threads")
		738
610	- this module is not thread-safe. You should only ever use this module	739	This module is not perl-pseudo-thread-safe. You should only ever use this
611	from the same thread (this requirement might be loosened in the future	740	module from the same thread (this requirement might be removed in the
612	to allow per-thread schedulers, but Coro::State does not yet allow	741	future to allow per-thread schedulers, but Coro::State does not yet allow
613	this).	742	this). I recommend disabling thread support and using processes, as having
		743	the windows process emulation enabled under unix roughly halves perl
		744	performance, even when not used.
		745
		746	=item coroutine switching not signal safe
		747
		748	You must not switch to another coroutine from within a signal handler
		749	(only relevant with %SIG - most event libraries provide safe signals).
		750
		751	That means you I<MUST NOT> call any function that might "block" the
		752	current coroutine - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or
		753	anything that calls those. Everything else, including calling C<ready>,
		754	works.
		755
		756	=back
		757
614		758
615	=head1 SEE ALSO	759	=head1 SEE ALSO
616		760
617	Lower level Configuration, Coroutine Environment: L<Coro::State>.	761	Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
618		762
619	Debugging: L<Coro::Debug>.	763	Debugging: L<Coro::Debug>.
620		764
621	Support/Utility: L<Coro::Specific>, L<Coro::Util>.	765	Support/Utility: L<Coro::Specific>, L<Coro::Util>.
622		766
623	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.	767	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
624		768
625	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>.	769	IO/Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>.
626		770
627	Compatibility: L<Coro::LWP>, L<Coro::Storable>, L<Coro::Select>.	771	Compatibility: L<Coro::LWP>, L<Coro::BDB>, L<Coro::Storable>, L<Coro::Select>.
628		772
629	Embedding: L<Coro::MakeMaker>.	773	XS API: L<Coro::MakeMaker>.
		774
		775	Low level Configuration, Coroutine Environment: L<Coro::State>.
630		776
631	=head1 AUTHOR	777	=head1 AUTHOR
632		778
633	Marc Lehmann <schmorp@schmorp.de>	779	Marc Lehmann <schmorp@schmorp.de>
634	http://home.schmorp.de/	780	http://home.schmorp.de/

Diff Legend

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

Comparing Coro/Coro.pm (file contents): Revision 1.178 by root, Thu Apr 17 22:33:10 2008 UTC vs. Revision 1.229 by root, Thu Nov 20 06:32:55 2008 UTC

Diff Legend

Comparing Coro/Coro.pm (file contents):
Revision 1.178 by root, Thu Apr 17 22:33:10 2008 UTC vs.
Revision 1.229 by root, Thu Nov 20 06:32:55 2008 UTC