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

Comparing Coro/Coro.pm (file contents):
Revision 1.148 by root, Fri Oct 5 20:11:25 2007 UTC vs.
Revision 1.265 by root, Sat Aug 22 22:36:23 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 = '4.01';	85	our $VERSION = 5.17;
56		86
57	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);	87	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
58	our %EXPORT_TAGS = (	88	our %EXPORT_TAGS = (
59	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	89	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
60	);	90	);
61	our @EXPORT_OK = (@{$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
192	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
193	environment.	197	environment in which coro are executed.
194		198
195	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
196	the coroutine. Likewise, when the coroutine dies, the program will exit,	200	the coro. Likewise, when the coro dies, the program will exit,
197	just as it would in the main program.	201	just as it would in the main program.
198		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
199	# create a new coroutine that just prints its arguments	206	Example: Create a new coro that just prints its arguments.
		207
200	async {	208	async {
201	print "@_\n";	209	print "@_\n";
202	} 1,2,3,4;	210	} 1,2,3,4;
203		211
204	=cut
205
206	sub async(&@) {
207	my $coro = new Coro @_;
208	$coro->ready;
209	$coro
210	}
211
212	=item async_pool { ... } [@args...]	212	=item async_pool { ... } [@args...]
213		213
214	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
215	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
216	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 :).
217		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
218	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
219	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
220	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>
221	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,
222	which somehow defeats the purpose of pooling.	227	which somehow defeats the purpose of pooling (but is fine in the
		228	exceptional case).
223		229
224	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
225	disabled, the description will be reset and the default output filehandle	231	disabled, the description will be reset and the default output filehandle
226	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
227	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
228	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
229	done by using local as in C< local $/ >.	235	simply done by using local as in: C<< local $/ >>.
230		236
231	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
232	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
233	required.	239	coros as required.
234		240
235	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
236	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
237	{ 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
238	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
239	(adjustable with $Coro::POOL_RSS) it will also exit.	245	(adjustable via $Coro::POOL_RSS) it will also be destroyed.
240		246
241	=cut	247	=cut
242		248
243	our $POOL_SIZE = 8;	249	our $POOL_SIZE = 8;
244	our $POOL_RSS = 16 * 1024;	250	our $POOL_RSS = 32 * 1024;
245	our @async_pool;	251	our @async_pool;
246		252
247	sub pool_handler {	253	sub pool_handler {
248	my $cb;
249
250	while () {	254	while () {
251	eval {	255	eval {
252	while () {	256	&{&_pool_handler} while 1;
253	_pool_1 $cb;
254	&$cb;
255	_pool_2 $cb;
256	&schedule;
257	}
258	};	257	};
259		258
260	last if $@ eq "\3terminate\2\n";
261	warn $@ if $@;	259	warn $@ if $@;
262	}	260	}
263	}	261	}
264		262
265	sub async_pool(&@) {	263	=back
266	# this is also inlined into the unlock_scheduler
267	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
268		264
269	$coro->{_invoke} = [@_];	265	=head1 STATIC METHODS
270	$coro->ready;
271		266
272	$coro	267	Static methods are actually functions that implicitly operate on the
273	}	268	current coro.
		269
		270	=over 4
274		271
275	=item schedule	272	=item schedule
276		273
277	Calls the scheduler. Please note that the current coroutine will not be put	274	Calls the scheduler. The scheduler will find the next coro that is
		275	to be run from the ready queue and switches to it. The next coro
		276	to be run is simply the one with the highest priority that is longest
		277	in its ready queue. If there is no coro ready, it will clal the
		278	C<$Coro::idle> hook.
		279
		280	Please note that the current coro will I<not> be put into the ready
278	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
279	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 >>,
280	ready.	283	thus waking you up.
281		284
282	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.
283		292
284	{	293	See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks.
285	# remember current coroutine
286	my $current = $Coro::current;
287		294
288	# register a hypothetical event handler	295	=item cede
289	on_event_invoke sub {	296
290	# wake up sleeping coroutine	297	"Cede" to other coros. This function puts the current coro into
291	$current->ready;	298	the ready queue and calls C<schedule>, which has the effect of giving
292	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
293	};	356	};
294		357
295	# call schedule until event occurred.	358	Coro::on_leave {
296	# in case we are woken up for other reasons	359	$ENV{TZ} = $old_tz;
297	# (current still defined), loop.	360	tzset; # restore old value
298	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.
299	}	365	};
300		366
301	=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.
302		370
303	"Cede" to other coroutines. This function puts the current coroutine into the	371	Another interesting example implements time-sliced multitasking using
304	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):
305	current "timeslice" to other coroutines of the same or higher priority.
306		373
307	Returns true if at least one coroutine switch has happened.	374	# "timeslice" the given block
		375	sub timeslice(&) {
		376	use Time::HiRes ();
308		377
309	=item Coro::cede_notself	378	Coro::on_enter {
		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	};
310		388
311	Works like cede, but is not exported by default and will cede to any	389	&{+shift};
312	coroutine, regardless of priority, once.	390	}
313		391
314	Returns true if at least one coroutine switch has happened.	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	};
315		399
316	=item terminate [arg...]
317
318	Terminates the current coroutine with the given status values (see L<cancel>).
319		400
320	=item killall	401	=item killall
321		402
322	Kills/terminates/cancels all coroutines except the currently running	403	Kills/terminates/cancels all coros except the currently running one.
323	one. This is useful after a fork, either in the child or the parent, as
324	usually only one of them should inherit the running coroutines.
325		404
326	=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.
327		409
328	sub terminate {	410	=cut
329	$current->cancel (@_);
330	}
331		411
332	sub killall {	412	sub killall {
333	for (Coro::State::list) {	413	for (Coro::State::list) {
334	$_->cancel	414	$_->cancel
335	if $_ != $current && UNIVERSAL::isa $_, "Coro";	415	if $_ != $current && UNIVERSAL::isa $_, "Coro";
336	}	416	}
337	}	417	}
338		418
339	=back	419	=back
340		420
341	# dynamic methods
342
343	=head2 COROUTINE METHODS	421	=head1 CORO OBJECT METHODS
344		422
345	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).
346		425
347	=over 4	426	=over 4
348		427
349	=item new Coro \&sub [, @args...]	428	=item new Coro \&sub [, @args...]
350		429
351	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
352	automatically terminates as if C<terminate> with the returned values were	431	automatically terminates as if C<terminate> with the returned values were
353	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
354	by calling the ready method.	433	queue by calling the ready method.
355		434
356	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
357	coroutine environment.	436	coro environment.
358		437
359	=cut	438	=cut
360		439
361	sub _run_coro {	440	sub _coro_run {
362	terminate &{+shift};	441	terminate &{+shift};
363	}	442	}
364		443
365	sub new {
366	my $class = shift;
367
368	$class->SUPER::new (\&_run_coro, @_)
369	}
370
371	=item $success = $coroutine->ready	444	=item $success = $coro->ready
372		445
373	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
374	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
375	and return false.	448	the ready queue, do nothing and return false.
376		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
377	=item $is_ready = $coroutine->is_ready	479	=item $is_ready = $coro->is_ready
378		480
379	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.
380		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
381	=item $coroutine->cancel (arg...)	495	=item $coro->cancel (arg...)
382		496
383	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
384	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
385	current coroutine.	499	current Coro.
386		500
387	=cut	501	=cut
388		502
389	sub cancel {	503	sub cancel {
390	my $self = shift;	504	my $self = shift;
391	$self->{_status} = [@_];
392		505
393	if ($current == $self) {	506	if ($current == $self) {
394	push @destroy, $self;	507	terminate @_;
395	$manager->ready;
396	&schedule while 1;
397	} else {	508	} else {
398	$self->_cancel;	509	$self->{_status} = [@_];
		510	Coro::State::cancel $self;
399	}	511	}
400	}	512	}
401		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
402	=item $coroutine->join	556	=item $coro->join
403		557
404	Wait until the coroutine terminates and return any values given to the	558	Wait until the coro terminates and return any values given to the
405	C<terminate> or C<cancel> functions. C<join> can be called concurrently	559	C<terminate> or C<cancel> functions. C<join> can be called concurrently
406	from multiple coroutines.	560	from multiple coro, and all will be resumed and given the status
		561	return once the C<$coro> terminates.
407		562
408	=cut	563	=cut
409		564
410	sub join {	565	sub join {
411	my $self = shift;	566	my $self = shift;
422	}	577	}
423		578
424	wantarray ? @{$self->{_status}} : $self->{_status}[0];	579	wantarray ? @{$self->{_status}} : $self->{_status}[0];
425	}	580	}
426		581
427	=item $coroutine->on_destroy (\&cb)	582	=item $coro->on_destroy (\&cb)
428		583
429	Registers a callback that is called when this coroutine gets destroyed,	584	Registers a callback that is called when this coro gets destroyed,
430	but before it is joined. The callback gets passed the terminate arguments,	585	but before it is joined. The callback gets passed the terminate arguments,
431	if any.	586	if any, and I<must not> die, under any circumstances.
432		587
433	=cut	588	=cut
434		589
435	sub on_destroy {	590	sub on_destroy {
436	my ($self, $cb) = @_;	591	my ($self, $cb) = @_;
437		592
438	push @{ $self->{_on_destroy} }, $cb;	593	push @{ $self->{_on_destroy} }, $cb;
439	}	594	}
440		595
441	=item $oldprio = $coroutine->prio ($newprio)	596	=item $oldprio = $coro->prio ($newprio)
442		597
443	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
444	coroutine. Higher priority coroutines get run before lower priority	599	coro. Higher priority coro get run before lower priority
445	coroutines. Priorities are small signed integers (currently -4 .. +3),	600	coro. Priorities are small signed integers (currently -4 .. +3),
446	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
447	to get then):	602	to get then):
448		603
449	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
450	3 > 1 > 0 > -1 > -3 > -4	605	3 > 1 > 0 > -1 > -3 > -4
451		606
452	# set priority to HIGH	607	# set priority to HIGH
453	current->prio(PRIO_HIGH);	608	current->prio (PRIO_HIGH);
454		609
455	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
456	existing coroutine.	611	existing coro.
457		612
458	Changing the priority of the current coroutine will take effect immediately,	613	Changing the priority of the current coro will take effect immediately,
459	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
460	running) will only take effect after the next schedule (of that	615	running) will only take effect after the next schedule (of that
461	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.
462		617
463	=item $newprio = $coroutine->nice ($change)	618	=item $newprio = $coro->nice ($change)
464		619
465	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.
466	higher values mean lower priority, just as in unix).	621	higher values mean lower priority, just as in unix).
467		622
468	=item $olddesc = $coroutine->desc ($newdesc)	623	=item $olddesc = $coro->desc ($newdesc)
469		624
470	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
471	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.
472		628
473	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
474	can modify this member directly if you wish.	630	string. You can modify this member directly if you wish.
475		631
476	=cut	632	=cut
477		633
478	sub desc {	634	sub desc {
479	my $old = $_[0]{desc};	635	my $old = $_[0]{desc};
480	$_[0]{desc} = $_[1] if @_ > 1;	636	$_[0]{desc} = $_[1] if @_ > 1;
481	$old;	637	$old;
482	}	638	}
483		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
484	=back	645	=back
485		646
486	=head2 GLOBAL FUNCTIONS	647	=head1 GLOBAL FUNCTIONS
487		648
488	=over 4	649	=over 4
489		650
490	=item Coro::nready	651	=item Coro::nready
491		652
492	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,
493	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
494	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>
495	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
496	that wakes up some coroutines.	658	coro.
497		659
498	=item my $guard = Coro::guard { ... }	660	=item my $guard = Coro::guard { ... }
499		661
500	This creates and returns a guard object. Nothing happens until the object	662	This function still exists, but is deprecated. Please use the
501	gets destroyed, in which case the codeblock given as argument will be	663	C<Guard::guard> function instead.
502	executed. This is useful to free locks or other resources in case of a
503	runtime error or when the coroutine gets canceled, as in both cases the
504	guard block will be executed. The guard object supports only one method,
505	C<< ->cancel >>, which will keep the codeblock from being executed.
506		664
507	Example: set some flag and clear it again when the coroutine gets canceled
508	or the function returns:
509
510	sub do_something {
511	my $guard = Coro::guard { $busy = 0 };
512	$busy = 1;
513
514	# do something that requires $busy to be true
515	}
516
517	=cut	665	=cut
518		666
519	sub guard(&) {	667	BEGIN { *guard = \&Guard::guard }
520	bless \(my $cb = $_[0]), "Coro::guard"
521	}
522
523	sub Coro::guard::cancel {
524	${$_[0]} = sub { };
525	}
526
527	sub Coro::guard::DESTROY {
528	${$_[0]}->();
529	}
530
531		668
532	=item unblock_sub { ... }	669	=item unblock_sub { ... }
533		670
534	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,
535	returning the new coderef. This means that the new coderef will return	672	returning a new coderef. Unblocking means that calling the new coderef
536	immediately without blocking, returning nothing, while the original code	673	will return immediately without blocking, returning nothing, while the
537	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.
538		676
539	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
540	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
541	of thread-safety). This means you must not block within event callbacks,	679	of reentrancy). This means you must not block within event callbacks,
542	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>.
543		682
544	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
545	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
546	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
547	disk.	686	disk, for example.
548		687
549	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
550	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>.
551		700
552	=cut	701	=cut
553		702
554	our @unblock_queue;	703	our @unblock_queue;
555		704
…		…
558	# return immediately and can be reused) and because we cannot cede	707	# return immediately and can be reused) and because we cannot cede
559	# inside an event callback.	708	# inside an event callback.
560	our $unblock_scheduler = new Coro sub {	709	our $unblock_scheduler = new Coro sub {
561	while () {	710	while () {
562	while (my $cb = pop @unblock_queue) {	711	while (my $cb = pop @unblock_queue) {
563	# this is an inlined copy of async_pool	712	&async_pool (@$cb);
564	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
565		713
566	$coro->{_invoke} = $cb;
567	$coro->ready;
568	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;
569	}	718	}
570	schedule; # sleep well	719	schedule; # sleep well
571	}	720	}
572	};	721	};
573	$unblock_scheduler->desc ("[unblock_sub scheduler]");	722	$unblock_scheduler->{desc} = "[unblock_sub scheduler]";
574		723
575	sub unblock_sub(&) {	724	sub unblock_sub(&) {
576	my $cb = shift;	725	my $cb = shift;
577		726
578	sub {	727	sub {
579	unshift @unblock_queue, [$cb, @_];	728	unshift @unblock_queue, [$cb, @_];
580	$unblock_scheduler->ready;	729	$unblock_scheduler->ready;
581	}	730	}
582	}	731	}
583		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
584	=back	754	=back
585		755
586	=cut	756	=cut
587		757
588	1;	758	1;
589		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
590	=head1 BUGS/LIMITATIONS	826	=head1 BUGS/LIMITATIONS
591		827
592	- you must make very sure that no coro is still active on global	828	=over 4
593	destruction. very bad things might happen otherwise (usually segfaults).
594		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
595	- 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
596	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
597	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
598	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
599		858
600	=head1 SEE ALSO	859	=head1 SEE ALSO
601		860
		861	Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
		862
		863	Debugging: L<Coro::Debug>.
		864
602	Support/Utility: L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.	865	Support/Utility: L<Coro::Specific>, L<Coro::Util>.
603		866
604	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>.
605		869
606	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.	870	I/O and Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>.
607		871
608	Embedding: L<Coro:MakeMaker>	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>.
		875
		876	XS API: L<Coro::MakeMaker>.
		877
		878	Low level Configuration, Thread Environment, Continuations: L<Coro::State>.
609		879
610	=head1 AUTHOR	880	=head1 AUTHOR
611		881
612	Marc Lehmann <schmorp@schmorp.de>	882	Marc Lehmann <schmorp@schmorp.de>
613	http://home.schmorp.de/	883	http://home.schmorp.de/

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Comparing Coro/Coro.pm (file contents): Revision 1.148 by root, Fri Oct 5 20:11:25 2007 UTC vs. Revision 1.265 by root, Sat Aug 22 22:36:23 2009 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.148 by root, Fri Oct 5 20:11:25 2007 UTC vs.
Revision 1.265 by root, Sat Aug 22 22:36:23 2009 UTC