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

Comparing Coro/Coro.pm (file contents):
Revision 1.128 by root, Wed Sep 19 21:39:15 2007 UTC vs.
Revision 1.248 by root, Mon Dec 15 15:03:31 2008 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), Coro provides a
		46	full shared address space, which makes communication between threads
		47	very easy. And threads are fast, too: disabling the Windows process
		48	emulation code in your perl and using Coro can easily result in a two to
		49	four times speed increase for your programs.
		50
		51	Coro achieves that by supporting multiple running interpreters that share
		52	data, which is especially useful to code pseudo-parallel processes and
		53	for event-based programming, such as multiple HTTP-GET requests running
		54	concurrently. See L<Coro::AnyEvent> to learn more on how to integrate Coro
		55	into an event-based environment.
		56
35	In this module, coroutines are defined as "callchain + lexical variables +	57	In this module, a thread is defined as "callchain + lexical variables +
36	@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,	58	@_ + $_ + $@ + $/ + 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	59	its own set of lexicals and its own set of perls most important global
38	variables.	60	variables (see L<Coro::State> for more configuration and background info).
		61
		62	See also the C<SEE ALSO> section at the end of this document - the Coro
		63	module family is quite large.
39		64
40	=cut	65	=cut
41		66
42	package Coro;	67	package Coro;
43		68
44	use strict;	69	use strict qw(vars subs);
45	no warnings "uninitialized";	70	no warnings "uninitialized";
46		71
		72	use Guard ();
		73
47	use Coro::State;	74	use Coro::State;
48		75
49	use base qw(Coro::State Exporter);	76	use base qw(Coro::State Exporter);
50		77
51	our $idle; # idle handler	78	our $idle; # idle handler
52	our $main; # main coroutine	79	our $main; # main coro
53	our $current; # current coroutine	80	our $current; # current coro
54		81
55	our $VERSION = '3.7';	82	our $VERSION = 5.13;
56		83
57	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);	84	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
58	our %EXPORT_TAGS = (	85	our %EXPORT_TAGS = (
59	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	86	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
60	);	87	);
61	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));	88	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
62		89
63	{	90	=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		91
97	=over 4	92	=over 4
98		93
99	=item $main	94	=item $Coro::main
100		95
101	This coroutine represents the main program.	96	This variable stores the Coro object that represents the main
		97	program. While you cna C<ready> it and do most other things you can do to
		98	coro, it is mainly useful to compare again C<$Coro::current>, to see
		99	whether you are running in the main program or not.
102		100
103	=cut	101	=cut
104		102
105	$main = new Coro;	103	# $main is now being initialised by Coro::State
106		104
107	=item $current (or as function: current)	105	=item $Coro::current
108		106
109	The current coroutine (the last coroutine switched to). The initial value	107	The Coro object representing the current coro (the last
		108	coro that the Coro scheduler switched to). The initial value is
110	is C<$main> (of course).	109	C<$Coro::main> (of course).
111		110
112	This variable is B<strictly> I<read-only>. It is provided for performance	111	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	112	value stored in it and use it as any other Coro object, but you must
114	C<Coro::current> function instead.	113	not otherwise modify the variable itself.
115		114
116	=cut	115	=cut
117		116
118	# maybe some other module used Coro::Specific before...
119	$main->{specific} = $current->{specific}
120	if $current;
121
122	_set_current $main;
123
124	sub current() { $current }	117	sub current() { $current } # [DEPRECATED]
125		118
126	=item $idle	119	=item $Coro::idle
127		120
		121	This variable is mainly useful to integrate Coro into event loops. It is
		122	usually better to rely on L<Coro::AnyEvent> or L<Coro::EV>, as this is
		123	pretty low-level functionality.
		124
		125	This variable stores either a Coro object or a callback.
		126
128	A callback that is called whenever the scheduler finds no ready coroutines	127	If it is a callback, the it is called whenever the scheduler finds no
129	to run. The default implementation prints "FATAL: deadlock detected" and	128	ready coros to run. The default implementation prints "FATAL:
130	exits, because the program has no other way to continue.	129	deadlock detected" and exits, because the program has no other way to
		130	continue.
131		131
		132	If it is a coro object, then this object will be readied (without
		133	invoking any ready hooks, however) when the scheduler finds no other ready
		134	coros to run.
		135
132	This hook is overwritten by modules such as C<Coro::Timer> and	136	This hook is overwritten by modules such as C<Coro::EV> and
133	C<Coro::Event> to wait on an external event that hopefully wake up a	137	C<Coro::AnyEvent> to wait on an external event that hopefully wake up a
134	coroutine so the scheduler can run it.	138	coro so the scheduler can run it.
		139
		140	Note that the callback I<must not>, under any circumstances, block
		141	the current coro. Normally, this is achieved by having an "idle
		142	coro" that calls the event loop and then blocks again, and then
		143	readying that coro in the idle handler, or by simply placing the idle
		144	coro in this variable.
		145
		146	See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this
		147	technique.
135		148
136	Please note that if your callback recursively invokes perl (e.g. for event	149	Please note that if your callback recursively invokes perl (e.g. for event
137	handlers), then it must be prepared to be called recursively.	150	handlers), then it must be prepared to be called recursively itself.
138		151
139	=cut	152	=cut
140		153
141	$idle = sub {	154	$idle = sub {
142	require Carp;	155	require Carp;
143	Carp::croak ("FATAL: deadlock detected");	156	Carp::croak ("FATAL: deadlock detected");
144	};	157	};
145		158
146	sub _cancel {
147	my ($self) = @_;
148
149	# free coroutine data and mark as destructed
150	$self->_destroy
151	or return;
152
153	# call all destruction callbacks
154	$_->(@{$self->{status}})
155	for @{(delete $self->{destroy_cb}) \|\| []};
156	}
157
158	# this coroutine is necessary because a coroutine	159	# this coro is necessary because a coro
159	# cannot destroy itself.	160	# cannot destroy itself.
160	my @destroy;	161	our @destroy;
161	my $manager;	162	our $manager;
162		163
163	$manager = new Coro sub {	164	$manager = new Coro sub {
164	while () {	165	while () {
165	(shift @destroy)->_cancel	166	Coro::State::cancel shift @destroy
166	while @destroy;	167	while @destroy;
167		168
168	&schedule;	169	&schedule;
169	}	170	}
170	};	171	};
171		172	$manager->{desc} = "[coro manager]";
172	$manager->prio (PRIO_MAX);	173	$manager->prio (PRIO_MAX);
173		174
174	# static methods. not really.
175
176	=back	175	=back
177		176
178	=head2 STATIC METHODS	177	=head1 SIMPLE CORO CREATION
179
180	Static methods are actually functions that operate on the current coroutine only.
181		178
182	=over 4	179	=over 4
183		180
184	=item async { ... } [@args...]	181	=item async { ... } [@args...]
185		182
186	Create a new asynchronous coroutine and return it's coroutine object	183	Create a new coro and return its Coro object (usually
187	(usually unused). When the sub returns the new coroutine is automatically	184	unused). The coro will be put into the ready queue, so
		185	it will start running automatically on the next scheduler run.
		186
		187	The first argument is a codeblock/closure that should be executed in the
		188	coro. When it returns argument returns the coro is automatically
188	terminated.	189	terminated.
189		190
		191	The remaining arguments are passed as arguments to the closure.
		192
		193	See the C<Coro::State::new> constructor for info about the coro
		194	environment in which coro are executed.
		195
190	Calling C<exit> in a coroutine will do the same as calling exit outside	196	Calling C<exit> in a coro will do the same as calling exit outside
191	the coroutine. Likewise, when the coroutine dies, the program will exit,	197	the coro. Likewise, when the coro dies, the program will exit,
192	just as it would in the main program.	198	just as it would in the main program.
193		199
		200	If you do not want that, you can provide a default C<die> handler, or
		201	simply avoid dieing (by use of C<eval>).
		202
194	# create a new coroutine that just prints its arguments	203	Example: Create a new coro that just prints its arguments.
		204
195	async {	205	async {
196	print "@_\n";	206	print "@_\n";
197	} 1,2,3,4;	207	} 1,2,3,4;
198		208
199	=cut	209	=cut
204	$coro	214	$coro
205	}	215	}
206		216
207	=item async_pool { ... } [@args...]	217	=item async_pool { ... } [@args...]
208		218
209	Similar to C<async>, but uses a coroutine pool, so you should not call	219	Similar to C<async>, but uses a coro pool, so you should not call
210	terminate or join (although you are allowed to), and you get a coroutine	220	terminate or join on it (although you are allowed to), and you get a
211	that might have executed other code already (which can be good or bad :).	221	coro that might have executed other code already (which can be good
		222	or bad :).
212		223
		224	On the plus side, this function is about twice as fast as creating (and
		225	destroying) a completely new coro, so if you need a lot of generic
		226	coros in quick successsion, use C<async_pool>, not C<async>.
		227
213	Also, the block is executed in an C<eval> context and a warning will be	228	The code block is executed in an C<eval> context and a warning will be
214	issued in case of an exception instead of terminating the program, as	229	issued in case of an exception instead of terminating the program, as
215	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>	230	C<async> does. As the coro is being reused, stuff like C<on_destroy>
216	will not work in the expected way, unless you call terminate or cancel,	231	will not work in the expected way, unless you call terminate or cancel,
217	which somehow defeats the purpose of pooling.	232	which somehow defeats the purpose of pooling (but is fine in the
		233	exceptional case).
218		234
219	The priority will be reset to C<0> after each job, otherwise the coroutine	235	The priority will be reset to C<0> after each run, tracing will be
220	will be re-used "as-is".	236	disabled, the description will be reset and the default output filehandle
		237	gets restored, so you can change all these. Otherwise the coro will
		238	be re-used "as-is": most notably if you change other per-coro global
		239	stuff such as C<$/> you I<must needs> revert that change, which is most
		240	simply done by using local as in: C<< local $/ >>.
221		241
222	The pool size is limited to 8 idle coroutines (this can be adjusted by	242	The idle pool size is limited to C<8> idle coros (this can be
223	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as	243	adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle
224	required.	244	coros as required.
225		245
226	If you are concerned about pooled coroutines growing a lot because a	246	If you are concerned about pooled coros growing a lot because a
227	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool {	247	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
228	terminate }> once per second or so to slowly replenish the pool.	248	{ terminate }> once per second or so to slowly replenish the pool. In
		249	addition to that, when the stacks used by a handler grows larger than 32kb
		250	(adjustable via $Coro::POOL_RSS) it will also be destroyed.
229		251
230	=cut	252	=cut
231		253
232	our $POOL_SIZE = 8;	254	our $POOL_SIZE = 8;
		255	our $POOL_RSS = 32 * 1024;
233	our @pool;	256	our @async_pool;
234		257
235	sub pool_handler {	258	sub pool_handler {
236	while () {	259	while () {
237	eval {	260	eval {
238	my ($cb, @arg) = @{ delete $current->{_invoke} or return };	261	&{&_pool_handler} while 1;
239	$cb->(@arg);
240	};	262	};
		263
241	warn $@ if $@;	264	warn $@ if $@;
242
243	last if @pool >= $POOL_SIZE;
244	push @pool, $current;
245
246	$current->save (Coro::State::SAVE_DEF);
247	$current->prio (0);
248	schedule;
249	}	265	}
250	}	266	}
251		267
252	sub async_pool(&@) {	268	=back
253	# this is also inlined into the unlock_scheduler	269
254	my $coro = (pop @pool) \|\| do {	270	=head1 STATIC METHODS
255	my $coro = new Coro \&pool_handler;	271
256	$coro->{desc} = "async_pool";	272	Static methods are actually functions that implicitly operate on the
257	$coro	273	current coro.
		274
		275	=over 4
		276
		277	=item schedule
		278
		279	Calls the scheduler. The scheduler will find the next coro that is
		280	to be run from the ready queue and switches to it. The next coro
		281	to be run is simply the one with the highest priority that is longest
		282	in its ready queue. If there is no coro ready, it will clal the
		283	C<$Coro::idle> hook.
		284
		285	Please note that the current coro will I<not> be put into the ready
		286	queue, so calling this function usually means you will never be called
		287	again unless something else (e.g. an event handler) calls C<< ->ready >>,
		288	thus waking you up.
		289
		290	This makes C<schedule> I<the> generic method to use to block the current
		291	coro and wait for events: first you remember the current coro in
		292	a variable, then arrange for some callback of yours to call C<< ->ready
		293	>> on that once some event happens, and last you call C<schedule> to put
		294	yourself to sleep. Note that a lot of things can wake your coro up,
		295	so you need to check whether the event indeed happened, e.g. by storing the
		296	status in a variable.
		297
		298	See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks.
		299
		300	=item cede
		301
		302	"Cede" to other coros. This function puts the current coro into
		303	the ready queue and calls C<schedule>, which has the effect of giving
		304	up the current "timeslice" to other coros of the same or higher
		305	priority. Once your coro gets its turn again it will automatically be
		306	resumed.
		307
		308	This function is often called C<yield> in other languages.
		309
		310	=item Coro::cede_notself
		311
		312	Works like cede, but is not exported by default and will cede to I<any>
		313	coro, regardless of priority. This is useful sometimes to ensure
		314	progress is made.
		315
		316	=item terminate [arg...]
		317
		318	Terminates the current coro with the given status values (see L<cancel>).
		319
		320	=item Coro::on_enter BLOCK, Coro::on_leave BLOCK
		321
		322	These function install enter and leave winders in the current scope. The
		323	enter block will be executed when on_enter is called and whenever the
		324	current coro is re-entered by the scheduler, while the leave block is
		325	executed whenever the current coro is blocked by the scheduler, and
		326	also when the containing scope is exited (by whatever means, be it exit,
		327	die, last etc.).
		328
		329	I<Neither invoking the scheduler, nor exceptions, are allowed within those
		330	BLOCKs>. That means: do not even think about calling C<die> without an
		331	eval, and do not even think of entering the scheduler in any way.
		332
		333	Since both BLOCKs are tied to the current scope, they will automatically
		334	be removed when the current scope exits.
		335
		336	These functions implement the same concept as C<dynamic-wind> in scheme
		337	does, and are useful when you want to localise some resource to a specific
		338	coro.
		339
		340	They slow down coro switching considerably for coros that use
		341	them (But coro switching is still reasonably fast if the handlers are
		342	fast).
		343
		344	These functions are best understood by an example: The following function
		345	will change the current timezone to "Antarctica/South_Pole", which
		346	requires a call to C<tzset>, but by using C<on_enter> and C<on_leave>,
		347	which remember/change the current timezone and restore the previous
		348	value, respectively, the timezone is only changes for the coro that
		349	installed those handlers.
		350
		351	use POSIX qw(tzset);
		352
		353	async {
		354	my $old_tz; # store outside TZ value here
		355
		356	Coro::on_enter {
		357	$old_tz = $ENV{TZ}; # remember the old value
		358
		359	$ENV{TZ} = "Antarctica/South_Pole";
		360	tzset; # enable new value
		361	};
		362
		363	Coro::on_leave {
		364	$ENV{TZ} = $old_tz;
		365	tzset; # restore old value
		366	};
		367
		368	# at this place, the timezone is Antarctica/South_Pole,
		369	# without disturbing the TZ of any other coro.
258	};	370	};
259		371
260	$coro->{_invoke} = [@_];	372	This can be used to localise about any resource (locale, uid, current
261	$coro->ready;	373	working directory etc.) to a block, despite the existance of other
		374	coros.
262		375
263	$coro	376	=item killall
264	}
265		377
266	=item schedule	378	Kills/terminates/cancels all coros except the currently running one.
267		379
268	Calls the scheduler. Please note that the current coroutine will not be put	380	Note that while this will try to free some of the main interpreter
269	into the ready queue, so calling this function usually means you will	381	resources if the calling coro isn't the main coro, but one
270	never be called again unless something else (e.g. an event handler) calls	382	cannot free all of them, so if a coro that is not the main coro
271	ready.	383	calls this function, there will be some one-time resource leak.
272		384
273	The canonical way to wait on external events is this:	385	=cut
274		386
		387	sub killall {
		388	for (Coro::State::list) {
		389	$_->cancel
		390	if $_ != $current && UNIVERSAL::isa $_, "Coro";
275	{	391	}
276	# remember current coroutine	392	}
		393
		394	=back
		395
		396	=head1 CORO OBJECT METHODS
		397
		398	These are the methods you can call on coro objects (or to create
		399	them).
		400
		401	=over 4
		402
		403	=item new Coro \&sub [, @args...]
		404
		405	Create a new coro and return it. When the sub returns, the coro
		406	automatically terminates as if C<terminate> with the returned values were
		407	called. To make the coro run you must first put it into the ready
		408	queue by calling the ready method.
		409
		410	See C<async> and C<Coro::State::new> for additional info about the
		411	coro environment.
		412
		413	=cut
		414
		415	sub _coro_run {
		416	terminate &{+shift};
		417	}
		418
		419	=item $success = $coro->ready
		420
		421	Put the given coro into the end of its ready queue (there is one
		422	queue for each priority) and return true. If the coro is already in
		423	the ready queue, do nothing and return false.
		424
		425	This ensures that the scheduler will resume this coro automatically
		426	once all the coro of higher priority and all coro of the same
		427	priority that were put into the ready queue earlier have been resumed.
		428
		429	=item $is_ready = $coro->is_ready
		430
		431	Returns true iff the Coro object is in the ready queue. Unless the Coro
		432	object gets destroyed, it will eventually be scheduled by the scheduler.
		433
		434	=item $is_running = $coro->is_running
		435
		436	Returns true iff the Coro object is currently running. Only one Coro object
		437	can ever be in the running state (but it currently is possible to have
		438	multiple running Coro::States).
		439
		440	=item $is_suspended = $coro->is_suspended
		441
		442	Returns true iff this Coro object has been suspended. Suspended Coros will
		443	not ever be scheduled.
		444
		445	=item $coro->cancel (arg...)
		446
		447	Terminates the given Coro and makes it return the given arguments as
		448	status (default: the empty list). Never returns if the Coro is the
		449	current Coro.
		450
		451	=cut
		452
		453	sub cancel {
		454	my $self = shift;
		455
		456	if ($current == $self) {
		457	terminate @_;
		458	} else {
		459	$self->{_status} = [@_];
		460	Coro::State::cancel $self;
		461	}
		462	}
		463
		464	=item $coro->schedule_to
		465
		466	Puts the current coro to sleep (like C<Coro::schedule>), but instead
		467	of continuing with the next coro from the ready queue, always switch to
		468	the given coro object (regardless of priority etc.). The readyness
		469	state of that coro isn't changed.
		470
		471	This is an advanced method for special cases - I'd love to hear about any
		472	uses for this one.
		473
		474	=item $coro->cede_to
		475
		476	Like C<schedule_to>, but puts the current coro into the ready
		477	queue. This has the effect of temporarily switching to the given
		478	coro, and continuing some time later.
		479
		480	This is an advanced method for special cases - I'd love to hear about any
		481	uses for this one.
		482
		483	=item $coro->throw ([$scalar])
		484
		485	If C<$throw> is specified and defined, it will be thrown as an exception
		486	inside the coro at the next convenient point in time. Otherwise
		487	clears the exception object.
		488
		489	Coro will check for the exception each time a schedule-like-function
		490	returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down
		491	>>, C<< Coro::Handle->readable >> and so on. Most of these functions
		492	detect this case and return early in case an exception is pending.
		493
		494	The exception object will be thrown "as is" with the specified scalar in
		495	C<$@>, i.e. if it is a string, no line number or newline will be appended
		496	(unlike with C<die>).
		497
		498	This can be used as a softer means than C<cancel> to ask a coro to
		499	end itself, although there is no guarantee that the exception will lead to
		500	termination, and if the exception isn't caught it might well end the whole
		501	program.
		502
		503	You might also think of C<throw> as being the moral equivalent of
		504	C<kill>ing a coro with a signal (in this case, a scalar).
		505
		506	=item $coro->join
		507
		508	Wait until the coro terminates and return any values given to the
		509	C<terminate> or C<cancel> functions. C<join> can be called concurrently
		510	from multiple coro, and all will be resumed and given the status
		511	return once the C<$coro> terminates.
		512
		513	=cut
		514
		515	sub join {
		516	my $self = shift;
		517
		518	unless ($self->{_status}) {
277	my $current = $Coro::current;	519	my $current = $current;
278		520
279	# register a hypothetical event handler	521	push @{$self->{_on_destroy}}, sub {
280	on_event_invoke sub {
281	# wake up sleeping coroutine
282	$current->ready;	522	$current->ready;
283	undef $current;	523	undef $current;
284	};	524	};
285		525
286	# call schedule until event occurred.
287	# in case we are woken up for other reasons
288	# (current still defined), loop.
289	Coro::schedule while $current;
290	}
291
292	=item cede
293
294	"Cede" to other coroutines. This function puts the current coroutine into the
295	ready queue and calls C<schedule>, which has the effect of giving up the
296	current "timeslice" to other coroutines of the same or higher priority.
297
298	Returns true if at least one coroutine switch has happened.
299
300	=item Coro::cede_notself
301
302	Works like cede, but is not exported by default and will cede to any
303	coroutine, regardless of priority, once.
304
305	Returns true if at least one coroutine switch has happened.
306
307	=item terminate [arg...]
308
309	Terminates the current coroutine with the given status values (see L<cancel>).
310
311	=cut
312
313	sub terminate {
314	$current->cancel (@_);
315	}
316
317	=back
318
319	# dynamic methods
320
321	=head2 COROUTINE METHODS
322
323	These are the methods you can call on coroutine objects.
324
325	=over 4
326
327	=item new Coro \&sub [, @args...]
328
329	Create a new coroutine and return it. When the sub returns the coroutine
330	automatically terminates as if C<terminate> with the returned values were
331	called. To make the coroutine run you must first put it into the ready queue
332	by calling the ready method.
333
334	See C<async> for additional discussion.
335
336	=cut
337
338	sub _run_coro {
339	terminate &{+shift};
340	}
341
342	sub new {
343	my $class = shift;
344
345	$class->SUPER::new (\&_run_coro, @_)
346	}
347
348	=item $success = $coroutine->ready
349
350	Put the given coroutine into the ready queue (according to it's priority)
351	and return true. If the coroutine is already in the ready queue, do nothing
352	and return false.
353
354	=item $is_ready = $coroutine->is_ready
355
356	Return wether the coroutine is currently the ready queue or not,
357
358	=item $coroutine->cancel (arg...)
359
360	Terminates the given coroutine and makes it return the given arguments as
361	status (default: the empty list). Never returns if the coroutine is the
362	current coroutine.
363
364	=cut
365
366	sub cancel {
367	my $self = shift;
368	$self->{status} = [@_];
369
370	if ($current == $self) {
371	push @destroy, $self;
372	$manager->ready;
373	&schedule while 1;
374	} else {
375	$self->_cancel;
376	}
377	}
378
379	=item $coroutine->join
380
381	Wait until the coroutine terminates and return any values given to the
382	C<terminate> or C<cancel> functions. C<join> can be called multiple times
383	from multiple coroutine.
384
385	=cut
386
387	sub join {
388	my $self = shift;
389
390	unless ($self->{status}) {
391	my $current = $current;
392
393	push @{$self->{destroy_cb}}, sub {
394	$current->ready;
395	undef $current;
396	};
397
398	&schedule while $current;	526	&schedule while $current;
399	}	527	}
400		528
401	wantarray ? @{$self->{status}} : $self->{status}[0];	529	wantarray ? @{$self->{_status}} : $self->{_status}[0];
402	}	530	}
403		531
404	=item $coroutine->on_destroy (\&cb)	532	=item $coro->on_destroy (\&cb)
405		533
406	Registers a callback that is called when this coroutine gets destroyed,	534	Registers a callback that is called when this coro gets destroyed,
407	but before it is joined. The callback gets passed the terminate arguments,	535	but before it is joined. The callback gets passed the terminate arguments,
408	if any.	536	if any, and I<must not> die, under any circumstances.
409		537
410	=cut	538	=cut
411		539
412	sub on_destroy {	540	sub on_destroy {
413	my ($self, $cb) = @_;	541	my ($self, $cb) = @_;
414		542
415	push @{ $self->{destroy_cb} }, $cb;	543	push @{ $self->{_on_destroy} }, $cb;
416	}	544	}
417		545
418	=item $oldprio = $coroutine->prio ($newprio)	546	=item $oldprio = $coro->prio ($newprio)
419		547
420	Sets (or gets, if the argument is missing) the priority of the	548	Sets (or gets, if the argument is missing) the priority of the
421	coroutine. Higher priority coroutines get run before lower priority	549	coro. Higher priority coro get run before lower priority
422	coroutines. Priorities are small signed integers (currently -4 .. +3),	550	coro. Priorities are small signed integers (currently -4 .. +3),
423	that you can refer to using PRIO_xxx constants (use the import tag :prio	551	that you can refer to using PRIO_xxx constants (use the import tag :prio
424	to get then):	552	to get then):
425		553
426	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN	554	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
427	3 > 1 > 0 > -1 > -3 > -4	555	3 > 1 > 0 > -1 > -3 > -4
428		556
429	# set priority to HIGH	557	# set priority to HIGH
430	current->prio(PRIO_HIGH);	558	current->prio (PRIO_HIGH);
431		559
432	The idle coroutine ($Coro::idle) always has a lower priority than any	560	The idle coro ($Coro::idle) always has a lower priority than any
433	existing coroutine.	561	existing coro.
434		562
435	Changing the priority of the current coroutine will take effect immediately,	563	Changing the priority of the current coro will take effect immediately,
436	but changing the priority of coroutines in the ready queue (but not	564	but changing the priority of coro in the ready queue (but not
437	running) will only take effect after the next schedule (of that	565	running) will only take effect after the next schedule (of that
438	coroutine). This is a bug that will be fixed in some future version.	566	coro). This is a bug that will be fixed in some future version.
439		567
440	=item $newprio = $coroutine->nice ($change)	568	=item $newprio = $coro->nice ($change)
441		569
442	Similar to C<prio>, but subtract the given value from the priority (i.e.	570	Similar to C<prio>, but subtract the given value from the priority (i.e.
443	higher values mean lower priority, just as in unix).	571	higher values mean lower priority, just as in unix).
444		572
445	=item $olddesc = $coroutine->desc ($newdesc)	573	=item $olddesc = $coro->desc ($newdesc)
446		574
447	Sets (or gets in case the argument is missing) the description for this	575	Sets (or gets in case the argument is missing) the description for this
448	coroutine. This is just a free-form string you can associate with a coroutine.	576	coro. This is just a free-form string you can associate with a
		577	coro.
		578
		579	This method simply sets the C<< $coro->{desc} >> member to the given
		580	string. You can modify this member directly if you wish.
449		581
450	=cut	582	=cut
451		583
452	sub desc {	584	sub desc {
453	my $old = $_[0]{desc};	585	my $old = $_[0]{desc};
454	$_[0]{desc} = $_[1] if @_ > 1;	586	$_[0]{desc} = $_[1] if @_ > 1;
455	$old;	587	$old;
456	}	588	}
457		589
		590	sub transfer {
		591	require Carp;
		592	Carp::croak ("You must not call ->transfer on Coro objects. Use Coro::State objects or the ->schedule_to method. Caught");
		593	}
		594
458	=back	595	=back
459		596
460	=head2 GLOBAL FUNCTIONS	597	=head1 GLOBAL FUNCTIONS
461		598
462	=over 4	599	=over 4
463		600
464	=item Coro::nready	601	=item Coro::nready
465		602
466	Returns the number of coroutines that are currently in the ready state,	603	Returns the number of coro that are currently in the ready state,
467	i.e. that can be switched to. The value C<0> means that the only runnable	604	i.e. that can be switched to by calling C<schedule> directory or
		605	indirectly. The value C<0> means that the only runnable coro is the
468	coroutine is the currently running one, so C<cede> would have no effect,	606	currently running one, so C<cede> would have no effect, and C<schedule>
469	and C<schedule> would cause a deadlock unless there is an idle handler	607	would cause a deadlock unless there is an idle handler that wakes up some
470	that wakes up some coroutines.	608	coro.
471		609
472	=item my $guard = Coro::guard { ... }	610	=item my $guard = Coro::guard { ... }
473		611
474	This creates and returns a guard object. Nothing happens until the object	612	This function still exists, but is deprecated. Please use the
475	gets destroyed, in which case the codeblock given as argument will be	613	C<Guard::guard> function instead.
476	executed. This is useful to free locks or other resources in case of a
477	runtime error or when the coroutine gets canceled, as in both cases the
478	guard block will be executed. The guard object supports only one method,
479	C<< ->cancel >>, which will keep the codeblock from being executed.
480		614
481	Example: set some flag and clear it again when the coroutine gets canceled
482	or the function returns:
483
484	sub do_something {
485	my $guard = Coro::guard { $busy = 0 };
486	$busy = 1;
487
488	# do something that requires $busy to be true
489	}
490
491	=cut	615	=cut
492		616
493	sub guard(&) {	617	BEGIN { *guard = \&Guard::guard }
494	bless \(my $cb = $_[0]), "Coro::guard"
495	}
496
497	sub Coro::guard::cancel {
498	${$_[0]} = sub { };
499	}
500
501	sub Coro::guard::DESTROY {
502	${$_[0]}->();
503	}
504
505		618
506	=item unblock_sub { ... }	619	=item unblock_sub { ... }
507		620
508	This utility function takes a BLOCK or code reference and "unblocks" it,	621	This utility function takes a BLOCK or code reference and "unblocks" it,
509	returning the new coderef. This means that the new coderef will return	622	returning a new coderef. Unblocking means that calling the new coderef
510	immediately without blocking, returning nothing, while the original code	623	will return immediately without blocking, returning nothing, while the
511	ref will be called (with parameters) from within its own coroutine.	624	original code ref will be called (with parameters) from within another
		625	coro.
512		626
513	The reason this function exists is that many event libraries (such as the	627	The reason this function exists is that many event libraries (such as the
514	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form	628	venerable L<Event\|Event> module) are not thread-safe (a weaker form
515	of thread-safety). This means you must not block within event callbacks,	629	of reentrancy). This means you must not block within event callbacks,
516	otherwise you might suffer from crashes or worse.	630	otherwise you might suffer from crashes or worse. The only event library
		631	currently known that is safe to use without C<unblock_sub> is L<EV>.
517		632
518	This function allows your callbacks to block by executing them in another	633	This function allows your callbacks to block by executing them in another
519	coroutine where it is safe to block. One example where blocking is handy	634	coro where it is safe to block. One example where blocking is handy
520	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to	635	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
521	disk.	636	disk, for example.
522		637
523	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when	638	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
524	creating event callbacks that want to block.	639	creating event callbacks that want to block.
		640
		641	If your handler does not plan to block (e.g. simply sends a message to
		642	another coro, or puts some other coro into the ready queue), there is
		643	no reason to use C<unblock_sub>.
		644
		645	Note that you also need to use C<unblock_sub> for any other callbacks that
		646	are indirectly executed by any C-based event loop. For example, when you
		647	use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it
		648	provides callbacks that are the result of some event callback, then you
		649	must not block either, or use C<unblock_sub>.
525		650
526	=cut	651	=cut
527		652
528	our @unblock_queue;	653	our @unblock_queue;
529		654
530	# we create a special coro because we want to cede,	655	# we create a special coro because we want to cede,
531	# to reduce pressure on the coro pool (because most callbacks	656	# to reduce pressure on the coro pool (because most callbacks
532	# return immediately and can be reused) and because we cannot cede	657	# return immediately and can be reused) and because we cannot cede
533	# inside an event callback.	658	# inside an event callback.
534	our $unblock_scheduler = async {	659	our $unblock_scheduler = new Coro sub {
535	while () {	660	while () {
536	while (my $cb = pop @unblock_queue) {	661	while (my $cb = pop @unblock_queue) {
537	# this is an inlined copy of async_pool	662	&async_pool (@$cb);
538	my $coro = (pop @pool or new Coro \&pool_handler);
539		663
540	$coro->{_invoke} = $cb;
541	$coro->ready;
542	cede; # for short-lived callbacks, this reduces pressure on the coro pool	664	# for short-lived callbacks, this reduces pressure on the coro pool
		665	# as the chance is very high that the async_poll coro will be back
		666	# in the idle state when cede returns
		667	cede;
543	}	668	}
544	schedule; # sleep well	669	schedule; # sleep well
545	}	670	}
546	};	671	};
		672	$unblock_scheduler->{desc} = "[unblock_sub scheduler]";
547		673
548	sub unblock_sub(&) {	674	sub unblock_sub(&) {
549	my $cb = shift;	675	my $cb = shift;
550		676
551	sub {	677	sub {
552	unshift @unblock_queue, [$cb, @_];	678	unshift @unblock_queue, [$cb, @_];
553	$unblock_scheduler->ready;	679	$unblock_scheduler->ready;
554	}	680	}
555	}	681	}
556		682
		683	=item $cb = Coro::rouse_cb
		684
		685	Create and return a "rouse callback". That's a code reference that,
		686	when called, will remember a copy of its arguments and notify the owner
		687	coro of the callback.
		688
		689	See the next function.
		690
		691	=item @args = Coro::rouse_wait [$cb]
		692
		693	Wait for the specified rouse callback (or the last one that was created in
		694	this coro).
		695
		696	As soon as the callback is invoked (or when the callback was invoked
		697	before C<rouse_wait>), it will return the arguments originally passed to
		698	the rouse callback.
		699
		700	See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example.
		701
557	=back	702	=back
558		703
559	=cut	704	=cut
560		705
561	1;	706	1;
562		707
		708	=head1 HOW TO WAIT FOR A CALLBACK
		709
		710	It is very common for a coro to wait for some callback to be
		711	called. This occurs naturally when you use coro in an otherwise
		712	event-based program, or when you use event-based libraries.
		713
		714	These typically register a callback for some event, and call that callback
		715	when the event occured. In a coro, however, you typically want to
		716	just wait for the event, simplyifying things.
		717
		718	For example C<< AnyEvent->child >> registers a callback to be called when
		719	a specific child has exited:
		720
		721	my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... });
		722
		723	But from within a coro, you often just want to write this:
		724
		725	my $status = wait_for_child $pid;
		726
		727	Coro offers two functions specifically designed to make this easy,
		728	C<Coro::rouse_cb> and C<Coro::rouse_wait>.
		729
		730	The first function, C<rouse_cb>, generates and returns a callback that,
		731	when invoked, will save its arguments and notify the coro that
		732	created the callback.
		733
		734	The second function, C<rouse_wait>, waits for the callback to be called
		735	(by calling C<schedule> to go to sleep) and returns the arguments
		736	originally passed to the callback.
		737
		738	Using these functions, it becomes easy to write the C<wait_for_child>
		739	function mentioned above:
		740
		741	sub wait_for_child($) {
		742	my ($pid) = @_;
		743
		744	my $watcher = AnyEvent->child (pid => $pid, cb => Coro::rouse_cb);
		745
		746	my ($rpid, $rstatus) = Coro::rouse_wait;
		747	$rstatus
		748	}
		749
		750	In the case where C<rouse_cb> and C<rouse_wait> are not flexible enough,
		751	you can roll your own, using C<schedule>:
		752
		753	sub wait_for_child($) {
		754	my ($pid) = @_;
		755
		756	# store the current coro in $current,
		757	# and provide result variables for the closure passed to ->child
		758	my $current = $Coro::current;
		759	my ($done, $rstatus);
		760
		761	# pass a closure to ->child
		762	my $watcher = AnyEvent->child (pid => $pid, cb => sub {
		763	$rstatus = $_[1]; # remember rstatus
		764	$done = 1; # mark $rstatus as valud
		765	});
		766
		767	# wait until the closure has been called
		768	schedule while !$done;
		769
		770	$rstatus
		771	}
		772
		773
563	=head1 BUGS/LIMITATIONS	774	=head1 BUGS/LIMITATIONS
564		775
565	- you must make very sure that no coro is still active on global	776	=over 4
566	destruction. very bad things might happen otherwise (usually segfaults).
567		777
		778	=item fork with pthread backend
		779
		780	When Coro is compiled using the pthread backend (which isn't recommended
		781	but required on many BSDs as their libcs are completely broken), then
		782	coro will not survive a fork. There is no known workaround except to
		783	fix your libc and use a saner backend.
		784
		785	=item perl process emulation ("threads")
		786
568	- this module is not thread-safe. You should only ever use this module	787	This module is not perl-pseudo-thread-safe. You should only ever use this
569	from the same thread (this requirement might be loosened in the future	788	module from the first thread (this requirement might be removed in the
570	to allow per-thread schedulers, but Coro::State does not yet allow	789	future to allow per-thread schedulers, but Coro::State does not yet allow
571	this).	790	this). I recommend disabling thread support and using processes, as having
		791	the windows process emulation enabled under unix roughly halves perl
		792	performance, even when not used.
		793
		794	=item coro switching is not signal safe
		795
		796	You must not switch to another coro from within a signal handler
		797	(only relevant with %SIG - most event libraries provide safe signals).
		798
		799	That means you I<MUST NOT> call any function that might "block" the
		800	current coro - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or
		801	anything that calls those. Everything else, including calling C<ready>,
		802	works.
		803
		804	=back
		805
572		806
573	=head1 SEE ALSO	807	=head1 SEE ALSO
574		808
		809	Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
		810
		811	Debugging: L<Coro::Debug>.
		812
575	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.	813	Support/Utility: L<Coro::Specific>, L<Coro::Util>.
576		814
577	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.	815	Locking and IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>,
		816	L<Coro::SemaphoreSet>, L<Coro::RWLock>.
578		817
579	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.	818	I/O and Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>.
580		819
581	Embedding: L<Coro:MakeMaker>	820	Compatibility with other modules: L<Coro::LWP> (but see also L<AnyEvent::HTTP> for
		821	a better-working alternative), L<Coro::BDB>, L<Coro::Storable>,
		822	L<Coro::Select>.
		823
		824	XS API: L<Coro::MakeMaker>.
		825
		826	Low level Configuration, Thread Environment, Continuations: L<Coro::State>.
582		827
583	=head1 AUTHOR	828	=head1 AUTHOR
584		829
585	Marc Lehmann <schmorp@schmorp.de>	830	Marc Lehmann <schmorp@schmorp.de>
586	http://home.schmorp.de/	831	http://home.schmorp.de/

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Comparing Coro/Coro.pm (file contents): Revision 1.128 by root, Wed Sep 19 21:39:15 2007 UTC vs. Revision 1.248 by root, Mon Dec 15 15:03:31 2008 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.128 by root, Wed Sep 19 21:39:15 2007 UTC vs.
Revision 1.248 by root, Mon Dec 15 15:03:31 2008 UTC