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

Comparing Coro/Coro.pm (file contents):
Revision 1.92 by root, Fri Dec 1 03:47:55 2006 UTC vs.
Revision 1.282 by root, Sun Dec 26 16:23:51 2010 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 to	31	For a tutorial-style introduction, please read the L<Coro::Intro>
24	threads but don't run in parallel.	32	manpage. This manpage mainly contains reference information.
25		33
		34	This module collection manages continuations in general, most often in
		35	the form of cooperative threads (also called coros, or simply "coro"
		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.
		43
		44	Unlike the so-called "Perl threads" (which are not actually real threads
		45	but only the windows process emulation (see section of same name for more
		46	details) ported to unix, and as such act as processes), Coro provides
		47	a full shared address space, which makes communication between threads
		48	very easy. And Coro's threads are fast, too: disabling the Windows
		49	process emulation code in your perl and using Coro can easily result in
		50	a two to four times speed increase for your programs. A parallel matrix
		51	multiplication benchmark runs over 300 times faster on a single core than
		52	perl's pseudo-threads on a quad core using 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
26	In this module, coroutines are defined as "callchain + lexical variables	60	In this module, a thread is defined as "callchain + lexical variables +
27	+ @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own	61	some package variables + C stack), that is, a thread has its own callchain,
28	callchain, it's own set of lexicals and it's own set of perl's most	62	its own set of lexicals and its own set of perls most important global
29	important global 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.
30		67
31	=cut	68	=cut
32		69
33	package Coro;	70	package Coro;
34		71
35	use strict;	72	use common::sense;
36	no warnings "uninitialized";	73
		74	use Carp ();
		75
		76	use Guard ();
37		77
38	use Coro::State;	78	use Coro::State;
39		79
40	use base qw(Coro::State Exporter);	80	use base qw(Coro::State Exporter);
41		81
42	our $idle; # idle handler	82	our $idle; # idle handler
43	our $main; # main coroutine	83	our $main; # main coro
44	our $current; # current coroutine	84	our $current; # current coro
45		85
46	our $VERSION = '3.0';	86	our $VERSION = 5.25;
47		87
48	our @EXPORT = qw(async cede schedule terminate current unblock_sub);	88	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub rouse_cb rouse_wait);
49	our %EXPORT_TAGS = (	89	our %EXPORT_TAGS = (
50	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	90	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
51	);	91	);
52	our @EXPORT_OK = @{$EXPORT_TAGS{prio}};	92	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
53		93
54	{	94	=head1 GLOBAL VARIABLES
55	my @async;
56	my $init;
57
58	# this way of handling attributes simply is NOT scalable ;()
59	sub import {
60	no strict 'refs';
61
62	Coro->export_to_level(1, @_);
63
64	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
65	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
66	my ($package, $ref) = (shift, shift);
67	my @attrs;
68	for (@_) {
69	if ($_ eq "Coro") {
70	push @async, $ref;
71	unless ($init++) {
72	eval q{
73	sub INIT {
74	&async(pop @async) while @async;
75	}
76	};
77	}
78	} else {
79	push @attrs, $_;
80	}
81	}
82	return $old ? $old->($package, $ref, @attrs) : @attrs;
83	};
84	}
85
86	}
87		95
88	=over 4	96	=over 4
89		97
90	=item $main	98	=item $Coro::main
91		99
92	This coroutine represents the main program.	100	This variable stores the Coro object that represents the main
		101	program. While you cna C<ready> it and do most other things you can do to
		102	coro, it is mainly useful to compare again C<$Coro::current>, to see
		103	whether you are running in the main program or not.
93		104
94	=cut	105	=cut
95		106
96	$main = new Coro;	107	# $main is now being initialised by Coro::State
97		108
98	=item $current (or as function: current)	109	=item $Coro::current
99		110
100	The current coroutine (the last coroutine switched to). The initial value	111	The Coro object representing the current coro (the last
		112	coro that the Coro scheduler switched to). The initial value is
101	is C<$main> (of course).	113	C<$Coro::main> (of course).
102		114
103	This variable is B<strictly> I<read-only>. It is provided for performance	115	This variable is B<strictly> I<read-only>. You can take copies of the
104	reasons. If performance is not essentiel you are encouraged to use the	116	value stored in it and use it as any other Coro object, but you must
105	C<Coro::current> function instead.	117	not otherwise modify the variable itself.
106		118
107	=cut	119	=cut
108		120
109	# maybe some other module used Coro::Specific before...
110	if ($current) {
111	$main->{specific} = $current->{specific};
112	}
113
114	$current = $main;
115
116	sub current() { $current }	121	sub current() { $current } # [DEPRECATED]
117		122
118	=item $idle	123	=item $Coro::idle
119		124
120	A callback that is called whenever the scheduler finds no ready coroutines	125	This variable is mainly useful to integrate Coro into event loops. It is
		126	usually better to rely on L<Coro::AnyEvent> or L<Coro::EV>, as this is
		127	pretty low-level functionality.
		128
		129	This variable stores a Coro object that is put into the ready queue when
		130	there are no other ready threads (without invoking any ready hooks).
		131
121	to run. The default implementation prints "FATAL: deadlock detected" and	132	The default implementation dies with "FATAL: deadlock detected.", followed
122	exits, because the program has no other way to continue.	133	by a thread listing, because the program has no other way to continue.
123		134
124	This hook is overwritten by modules such as C<Coro::Timer> and	135	This hook is overwritten by modules such as C<Coro::EV> and
125	C<Coro::Event> to wait on an external event that hopefully wake up a	136	C<Coro::AnyEvent> to wait on an external event that hopefully wake up a
126	coroutine so the scheduler can run it.	137	coro so the scheduler can run it.
127		138
128	Please note that if your callback recursively invokes perl (e.g. for event	139	See L<Coro::EV> or L<Coro::AnyEvent> for examples of using this technique.
129	handlers), then it must be prepared to be called recursively.
130		140
131	=cut	141	=cut
132		142
133	$idle = sub {	143	# \|\|= because other modules could have provided their own by now
		144	$idle \|\|= new Coro sub {
		145	require Coro::Debug;
134	print STDERR "FATAL: deadlock detected\n";	146	die "FATAL: deadlock detected.\n"
135	exit (51);	147	. Coro::Debug::ps_listing ();
136	};	148	};
137		149
138	# this coroutine is necessary because a coroutine	150	# this coro is necessary because a coro
139	# cannot destroy itself.	151	# cannot destroy itself.
140	my @destroy;	152	our @destroy;
		153	our $manager;
		154
141	my $manager; $manager = new Coro sub {	155	$manager = new Coro sub {
142	while () {	156	while () {
143	# by overwriting the state object with the manager we destroy it	157	Coro::State::cancel shift @destroy
144	# while still being able to schedule this coroutine (in case it has
145	# been readied multiple times. this is harmless since the manager
146	# can be called as many times as neccessary and will always
147	# remove itself from the runqueue
148	while (@destroy) {	158	while @destroy;
149	my $coro = pop @destroy;
150	$coro->{status} \|\|= [];
151	$_->ready for @{delete $coro->{join} \|\| []};
152		159
153	# the next line destroys the coro state, but keeps the
154	# coroutine itself intact (we basically make it a zombie
155	# coroutine that always runs the manager thread, so it's possible
156	# to transfer() to this coroutine).
157	$coro->_clone_state_from ($manager);
158	}
159	&schedule;	160	&schedule;
160	}	161	}
161	};	162	};
162		163	$manager->{desc} = "[coro manager]";
163	# static methods. not really.	164	$manager->prio (PRIO_MAX);
164		165
165	=back	166	=back
166		167
167	=head2 STATIC METHODS	168	=head1 SIMPLE CORO CREATION
168
169	Static methods are actually functions that operate on the current coroutine only.
170		169
171	=over 4	170	=over 4
172		171
173	=item async { ... } [@args...]	172	=item async { ... } [@args...]
174		173
175	Create a new asynchronous coroutine and return it's coroutine object	174	Create a new coro and return its Coro object (usually
176	(usually unused). When the sub returns the new coroutine is automatically	175	unused). The coro will be put into the ready queue, so
		176	it will start running automatically on the next scheduler run.
		177
		178	The first argument is a codeblock/closure that should be executed in the
		179	coro. When it returns argument returns the coro is automatically
177	terminated.	180	terminated.
178		181
179	Calling C<exit> in a coroutine will not work correctly, so do not do that.	182	The remaining arguments are passed as arguments to the closure.
180		183
181	When the coroutine dies, the program will exit, just as in the main	184	See the C<Coro::State::new> constructor for info about the coro
182	program.	185	environment in which coro are executed.
183		186
		187	Calling C<exit> in a coro will do the same as calling exit outside
		188	the coro. Likewise, when the coro dies, the program will exit,
		189	just as it would in the main program.
		190
		191	If you do not want that, you can provide a default C<die> handler, or
		192	simply avoid dieing (by use of C<eval>).
		193
184	# create a new coroutine that just prints its arguments	194	Example: Create a new coro that just prints its arguments.
		195
185	async {	196	async {
186	print "@_\n";	197	print "@_\n";
187	} 1,2,3,4;	198	} 1,2,3,4;
188		199
189	=cut	200	=item async_pool { ... } [@args...]
190		201
191	sub async(&@) {	202	Similar to C<async>, but uses a coro pool, so you should not call
192	my $pid = new Coro @_;	203	terminate or join on it (although you are allowed to), and you get a
193	$pid->ready;	204	coro that might have executed other code already (which can be good
194	$pid	205	or bad :).
		206
		207	On the plus side, this function is about twice as fast as creating (and
		208	destroying) a completely new coro, so if you need a lot of generic
		209	coros in quick successsion, use C<async_pool>, not C<async>.
		210
		211	The code block is executed in an C<eval> context and a warning will be
		212	issued in case of an exception instead of terminating the program, as
		213	C<async> does. As the coro is being reused, stuff like C<on_destroy>
		214	will not work in the expected way, unless you call terminate or cancel,
		215	which somehow defeats the purpose of pooling (but is fine in the
		216	exceptional case).
		217
		218	The priority will be reset to C<0> after each run, tracing will be
		219	disabled, the description will be reset and the default output filehandle
		220	gets restored, so you can change all these. Otherwise the coro will
		221	be re-used "as-is": most notably if you change other per-coro global
		222	stuff such as C<$/> you I<must needs> revert that change, which is most
		223	simply done by using local as in: C<< local $/ >>.
		224
		225	The idle pool size is limited to C<8> idle coros (this can be
		226	adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle
		227	coros as required.
		228
		229	If you are concerned about pooled coros growing a lot because a
		230	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
		231	{ terminate }> once per second or so to slowly replenish the pool. In
		232	addition to that, when the stacks used by a handler grows larger than 32kb
		233	(adjustable via $Coro::POOL_RSS) it will also be destroyed.
		234
		235	=cut
		236
		237	our $POOL_SIZE = 8;
		238	our $POOL_RSS = 32 * 1024;
		239	our @async_pool;
		240
		241	sub pool_handler {
		242	while () {
		243	eval {
		244	&{&_pool_handler} while 1;
		245	};
		246
		247	warn $@ if $@;
		248	}
195	}	249	}
196		250
		251	=back
		252
		253	=head1 STATIC METHODS
		254
		255	Static methods are actually functions that implicitly operate on the
		256	current coro.
		257
		258	=over 4
		259
197	=item schedule	260	=item schedule
198		261
199	Calls the scheduler. Please note that the current coroutine will not be put	262	Calls the scheduler. The scheduler will find the next coro that is
		263	to be run from the ready queue and switches to it. The next coro
		264	to be run is simply the one with the highest priority that is longest
		265	in its ready queue. If there is no coro ready, it will call the
		266	C<$Coro::idle> hook.
		267
		268	Please note that the current coro will I<not> be put into the ready
200	into the ready queue, so calling this function usually means you will	269	queue, so calling this function usually means you will never be called
201	never be called again unless something else (e.g. an event handler) calls	270	again unless something else (e.g. an event handler) calls C<< ->ready >>,
202	ready.	271	thus waking you up.
203		272
204	The canonical way to wait on external events is this:	273	This makes C<schedule> I<the> generic method to use to block the current
		274	coro and wait for events: first you remember the current coro in
		275	a variable, then arrange for some callback of yours to call C<< ->ready
		276	>> on that once some event happens, and last you call C<schedule> to put
		277	yourself to sleep. Note that a lot of things can wake your coro up,
		278	so you need to check whether the event indeed happened, e.g. by storing the
		279	status in a variable.
205		280
		281	See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks.
		282
		283	=item cede
		284
		285	"Cede" to other coros. This function puts the current coro into
		286	the ready queue and calls C<schedule>, which has the effect of giving
		287	up the current "timeslice" to other coros of the same or higher
		288	priority. Once your coro gets its turn again it will automatically be
		289	resumed.
		290
		291	This function is often called C<yield> in other languages.
		292
		293	=item Coro::cede_notself
		294
		295	Works like cede, but is not exported by default and will cede to I<any>
		296	coro, regardless of priority. This is useful sometimes to ensure
		297	progress is made.
		298
		299	=item terminate [arg...]
		300
		301	Terminates the current coro with the given status values (see L<cancel>).
		302
		303	=item Coro::on_enter BLOCK, Coro::on_leave BLOCK
		304
		305	These function install enter and leave winders in the current scope. The
		306	enter block will be executed when on_enter is called and whenever the
		307	current coro is re-entered by the scheduler, while the leave block is
		308	executed whenever the current coro is blocked by the scheduler, and
		309	also when the containing scope is exited (by whatever means, be it exit,
		310	die, last etc.).
		311
		312	I<Neither invoking the scheduler, nor exceptions, are allowed within those
		313	BLOCKs>. That means: do not even think about calling C<die> without an
		314	eval, and do not even think of entering the scheduler in any way.
		315
		316	Since both BLOCKs are tied to the current scope, they will automatically
		317	be removed when the current scope exits.
		318
		319	These functions implement the same concept as C<dynamic-wind> in scheme
		320	does, and are useful when you want to localise some resource to a specific
		321	coro.
		322
		323	They slow down thread switching considerably for coros that use them
		324	(about 40% for a BLOCK with a single assignment, so thread switching is
		325	still reasonably fast if the handlers are fast).
		326
		327	These functions are best understood by an example: The following function
		328	will change the current timezone to "Antarctica/South_Pole", which
		329	requires a call to C<tzset>, but by using C<on_enter> and C<on_leave>,
		330	which remember/change the current timezone and restore the previous
		331	value, respectively, the timezone is only changed for the coro that
		332	installed those handlers.
		333
		334	use POSIX qw(tzset);
		335
		336	async {
		337	my $old_tz; # store outside TZ value here
		338
		339	Coro::on_enter {
		340	$old_tz = $ENV{TZ}; # remember the old value
		341
		342	$ENV{TZ} = "Antarctica/South_Pole";
		343	tzset; # enable new value
		344	};
		345
		346	Coro::on_leave {
		347	$ENV{TZ} = $old_tz;
		348	tzset; # restore old value
		349	};
		350
		351	# at this place, the timezone is Antarctica/South_Pole,
		352	# without disturbing the TZ of any other coro.
		353	};
		354
		355	This can be used to localise about any resource (locale, uid, current
		356	working directory etc.) to a block, despite the existance of other
		357	coros.
		358
		359	Another interesting example implements time-sliced multitasking using
		360	interval timers (this could obviously be optimised, but does the job):
		361
		362	# "timeslice" the given block
		363	sub timeslice(&) {
		364	use Time::HiRes ();
		365
		366	Coro::on_enter {
		367	# on entering the thread, we set an VTALRM handler to cede
		368	$SIG{VTALRM} = sub { cede };
		369	# and then start the interval timer
		370	Time::HiRes::setitimer &Time::HiRes::ITIMER_VIRTUAL, 0.01, 0.01;
		371	};
		372	Coro::on_leave {
		373	# on leaving the thread, we stop the interval timer again
		374	Time::HiRes::setitimer &Time::HiRes::ITIMER_VIRTUAL, 0, 0;
		375	};
		376
		377	&{+shift};
		378	}
		379
		380	# use like this:
		381	timeslice {
		382	# The following is an endless loop that would normally
		383	# monopolise the process. Since it runs in a timesliced
		384	# environment, it will regularly cede to other threads.
		385	while () { }
		386	};
		387
		388
		389	=item killall
		390
		391	Kills/terminates/cancels all coros except the currently running one.
		392
		393	Note that while this will try to free some of the main interpreter
		394	resources if the calling coro isn't the main coro, but one
		395	cannot free all of them, so if a coro that is not the main coro
		396	calls this function, there will be some one-time resource leak.
		397
		398	=cut
		399
		400	sub killall {
		401	for (Coro::State::list) {
		402	$_->cancel
		403	if $_ != $current && UNIVERSAL::isa $_, "Coro";
206	{	404	}
207	# remember current coroutine	405	}
		406
		407	=back
		408
		409	=head1 CORO OBJECT METHODS
		410
		411	These are the methods you can call on coro objects (or to create
		412	them).
		413
		414	=over 4
		415
		416	=item new Coro \&sub [, @args...]
		417
		418	Create a new coro and return it. When the sub returns, the coro
		419	automatically terminates as if C<terminate> with the returned values were
		420	called. To make the coro run you must first put it into the ready
		421	queue by calling the ready method.
		422
		423	See C<async> and C<Coro::State::new> for additional info about the
		424	coro environment.
		425
		426	=cut
		427
		428	sub _coro_run {
		429	terminate &{+shift};
		430	}
		431
		432	=item $success = $coro->ready
		433
		434	Put the given coro into the end of its ready queue (there is one
		435	queue for each priority) and return true. If the coro is already in
		436	the ready queue, do nothing and return false.
		437
		438	This ensures that the scheduler will resume this coro automatically
		439	once all the coro of higher priority and all coro of the same
		440	priority that were put into the ready queue earlier have been resumed.
		441
		442	=item $coro->suspend
		443
		444	Suspends the specified coro. A suspended coro works just like any other
		445	coro, except that the scheduler will not select a suspended coro for
		446	execution.
		447
		448	Suspending a coro can be useful when you want to keep the coro from
		449	running, but you don't want to destroy it, or when you want to temporarily
		450	freeze a coro (e.g. for debugging) to resume it later.
		451
		452	A scenario for the former would be to suspend all (other) coros after a
		453	fork and keep them alive, so their destructors aren't called, but new
		454	coros can be created.
		455
		456	=item $coro->resume
		457
		458	If the specified coro was suspended, it will be resumed. Note that when
		459	the coro was in the ready queue when it was suspended, it might have been
		460	unreadied by the scheduler, so an activation might have been lost.
		461
		462	To avoid this, it is best to put a suspended coro into the ready queue
		463	unconditionally, as every synchronisation mechanism must protect itself
		464	against spurious wakeups, and the one in the Coro family certainly do
		465	that.
		466
		467	=item $is_ready = $coro->is_ready
		468
		469	Returns true iff the Coro object is in the ready queue. Unless the Coro
		470	object gets destroyed, it will eventually be scheduled by the scheduler.
		471
		472	=item $is_running = $coro->is_running
		473
		474	Returns true iff the Coro object is currently running. Only one Coro object
		475	can ever be in the running state (but it currently is possible to have
		476	multiple running Coro::States).
		477
		478	=item $is_suspended = $coro->is_suspended
		479
		480	Returns true iff this Coro object has been suspended. Suspended Coros will
		481	not ever be scheduled.
		482
		483	=item $coro->cancel (arg...)
		484
		485	Terminates the given Coro and makes it return the given arguments as
		486	status (default: the empty list). Never returns if the Coro is the
		487	current Coro.
		488
		489	=cut
		490
		491	sub cancel {
		492	my $self = shift;
		493
		494	if ($current == $self) {
		495	terminate @_;
		496	} else {
		497	$self->{_status} = [@_];
		498	Coro::State::cancel $self;
		499	}
		500	}
		501
		502	=item $coro->schedule_to
		503
		504	Puts the current coro to sleep (like C<Coro::schedule>), but instead
		505	of continuing with the next coro from the ready queue, always switch to
		506	the given coro object (regardless of priority etc.). The readyness
		507	state of that coro isn't changed.
		508
		509	This is an advanced method for special cases - I'd love to hear about any
		510	uses for this one.
		511
		512	=item $coro->cede_to
		513
		514	Like C<schedule_to>, but puts the current coro into the ready
		515	queue. This has the effect of temporarily switching to the given
		516	coro, and continuing some time later.
		517
		518	This is an advanced method for special cases - I'd love to hear about any
		519	uses for this one.
		520
		521	=item $coro->throw ([$scalar])
		522
		523	If C<$throw> is specified and defined, it will be thrown as an exception
		524	inside the coro at the next convenient point in time. Otherwise
		525	clears the exception object.
		526
		527	Coro will check for the exception each time a schedule-like-function
		528	returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down
		529	>>, C<< Coro::Handle->readable >> and so on. Most of these functions
		530	detect this case and return early in case an exception is pending.
		531
		532	The exception object will be thrown "as is" with the specified scalar in
		533	C<$@>, i.e. if it is a string, no line number or newline will be appended
		534	(unlike with C<die>).
		535
		536	This can be used as a softer means than C<cancel> to ask a coro to
		537	end itself, although there is no guarantee that the exception will lead to
		538	termination, and if the exception isn't caught it might well end the whole
		539	program.
		540
		541	You might also think of C<throw> as being the moral equivalent of
		542	C<kill>ing a coro with a signal (in this case, a scalar).
		543
		544	=item $coro->join
		545
		546	Wait until the coro terminates and return any values given to the
		547	C<terminate> or C<cancel> functions. C<join> can be called concurrently
		548	from multiple coro, and all will be resumed and given the status
		549	return once the C<$coro> terminates.
		550
		551	=cut
		552
		553	sub join {
		554	my $self = shift;
		555
		556	unless ($self->{_status}) {
208	my $current = $Coro::current;	557	my $current = $current;
209		558
210	# register a hypothetical event handler	559	push @{$self->{_on_destroy}}, sub {
211	on_event_invoke sub {
212	# wake up sleeping coroutine
213	$current->ready;	560	$current->ready;
214	undef $current;	561	undef $current;
215	};	562	};
216		563
217	# call schedule until event occured.
218	# in case we are woken up for other reasons
219	# (current still defined), loop.
220	Coro::schedule while $current;	564	&schedule while $current;
221	}	565	}
222		566
223	=item cede	567	wantarray ? @{$self->{_status}} : $self->{_status}[0];
224
225	"Cede" to other coroutines. This function puts the current coroutine into the
226	ready queue and calls C<schedule>, which has the effect of giving up the
227	current "timeslice" to other coroutines of the same or higher priority.
228
229	=item terminate [arg...]
230
231	Terminates the current coroutine with the given status values (see L<cancel>).
232
233	=cut
234
235	sub terminate {
236	$current->cancel (@_);
237	}	568	}
238		569
239	=back	570	=item $coro->on_destroy (\&cb)
240		571
241	# dynamic methods	572	Registers a callback that is called when this coro gets destroyed,
		573	but before it is joined. The callback gets passed the terminate arguments,
		574	if any, and I<must not> die, under any circumstances.
242		575
243	=head2 COROUTINE METHODS
244
245	These are the methods you can call on coroutine objects.
246
247	=over 4
248
249	=item new Coro \&sub [, @args...]
250
251	Create a new coroutine and return it. When the sub returns the coroutine
252	automatically terminates as if C<terminate> with the returned values were
253	called. To make the coroutine run you must first put it into the ready queue
254	by calling the ready method.
255
256	Calling C<exit> in a coroutine will not work correctly, so do not do that.
257
258	=cut	576	=cut
259		577
260	sub _new_coro {	578	sub on_destroy {
261	terminate &{+shift};	579	my ($self, $cb) = @_;
		580
		581	push @{ $self->{_on_destroy} }, $cb;
262	}	582	}
263		583
264	sub new {
265	my $class = shift;
266
267	$class->SUPER::new (\&_new_coro, @_)
268	}
269
270	=item $success = $coroutine->ready
271
272	Put the given coroutine into the ready queue (according to it's priority)
273	and return true. If the coroutine is already in the ready queue, do nothing
274	and return false.
275
276	=item $is_ready = $coroutine->is_ready
277
278	Return wether the coroutine is currently the ready queue or not,
279
280	=item $coroutine->cancel (arg...)
281
282	Terminates the given coroutine and makes it return the given arguments as
283	status (default: the empty list).
284
285	=cut
286
287	sub cancel {
288	my $self = shift;
289	$self->{status} = [@_];
290	push @destroy, $self;
291	$manager->ready;
292	&schedule if $current == $self;
293	}
294
295	=item $coroutine->join
296
297	Wait until the coroutine terminates and return any values given to the
298	C<terminate> or C<cancel> functions. C<join> can be called multiple times
299	from multiple coroutine.
300
301	=cut
302
303	sub join {
304	my $self = shift;
305	unless ($self->{status}) {
306	push @{$self->{join}}, $current;
307	&schedule;
308	}
309	wantarray ? @{$self->{status}} : $self->{status}[0];
310	}
311
312	=item $oldprio = $coroutine->prio ($newprio)	584	=item $oldprio = $coro->prio ($newprio)
313		585
314	Sets (or gets, if the argument is missing) the priority of the	586	Sets (or gets, if the argument is missing) the priority of the
315	coroutine. Higher priority coroutines get run before lower priority	587	coro. Higher priority coro get run before lower priority
316	coroutines. Priorities are small signed integers (currently -4 .. +3),	588	coro. Priorities are small signed integers (currently -4 .. +3),
317	that you can refer to using PRIO_xxx constants (use the import tag :prio	589	that you can refer to using PRIO_xxx constants (use the import tag :prio
318	to get then):	590	to get then):
319		591
320	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN	592	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
321	3 > 1 > 0 > -1 > -3 > -4	593	3 > 1 > 0 > -1 > -3 > -4
322		594
323	# set priority to HIGH	595	# set priority to HIGH
324	current->prio(PRIO_HIGH);	596	current->prio (PRIO_HIGH);
325		597
326	The idle coroutine ($Coro::idle) always has a lower priority than any	598	The idle coro ($Coro::idle) always has a lower priority than any
327	existing coroutine.	599	existing coro.
328		600
329	Changing the priority of the current coroutine will take effect immediately,	601	Changing the priority of the current coro will take effect immediately,
330	but changing the priority of coroutines in the ready queue (but not	602	but changing the priority of coro in the ready queue (but not
331	running) will only take effect after the next schedule (of that	603	running) will only take effect after the next schedule (of that
332	coroutine). This is a bug that will be fixed in some future version.	604	coro). This is a bug that will be fixed in some future version.
333		605
334	=item $newprio = $coroutine->nice ($change)	606	=item $newprio = $coro->nice ($change)
335		607
336	Similar to C<prio>, but subtract the given value from the priority (i.e.	608	Similar to C<prio>, but subtract the given value from the priority (i.e.
337	higher values mean lower priority, just as in unix).	609	higher values mean lower priority, just as in unix).
338		610
339	=item $olddesc = $coroutine->desc ($newdesc)	611	=item $olddesc = $coro->desc ($newdesc)
340		612
341	Sets (or gets in case the argument is missing) the description for this	613	Sets (or gets in case the argument is missing) the description for this
342	coroutine. This is just a free-form string you can associate with a coroutine.	614	coro. This is just a free-form string you can associate with a
		615	coro.
		616
		617	This method simply sets the C<< $coro->{desc} >> member to the given
		618	string. You can modify this member directly if you wish, and in fact, this
		619	is often preferred to indicate major processing states that cna then be
		620	seen for example in a L<Coro::Debug> session:
		621
		622	sub my_long_function {
		623	local $Coro::current->{desc} = "now in my_long_function";
		624	...
		625	$Coro::current->{desc} = "my_long_function: phase 1";
		626	...
		627	$Coro::current->{desc} = "my_long_function: phase 2";
		628	...
		629	}
343		630
344	=cut	631	=cut
345		632
346	sub desc {	633	sub desc {
347	my $old = $_[0]{desc};	634	my $old = $_[0]{desc};
348	$_[0]{desc} = $_[1] if @_ > 1;	635	$_[0]{desc} = $_[1] if @_ > 1;
349	$old;	636	$old;
350	}	637	}
351		638
		639	sub transfer {
		640	require Carp;
		641	Carp::croak ("You must not call ->transfer on Coro objects. Use Coro::State objects or the ->schedule_to method. Caught");
		642	}
		643
352	=back	644	=back
353		645
354	=head2 UTILITY FUNCTIONS	646	=head1 GLOBAL FUNCTIONS
355		647
356	=over 4	648	=over 4
357		649
		650	=item Coro::nready
		651
		652	Returns the number of coro that are currently in the ready state,
		653	i.e. that can be switched to by calling C<schedule> directory or
		654	indirectly. The value C<0> means that the only runnable coro is the
		655	currently running one, so C<cede> would have no effect, and C<schedule>
		656	would cause a deadlock unless there is an idle handler that wakes up some
		657	coro.
		658
		659	=item my $guard = Coro::guard { ... }
		660
		661	This function still exists, but is deprecated. Please use the
		662	C<Guard::guard> function instead.
		663
		664	=cut
		665
		666	BEGIN { *guard = \&Guard::guard }
		667
358	=item unblock_sub { ... }	668	=item unblock_sub { ... }
359		669
360	This utility function takes a BLOCK or code reference and "unblocks" it,	670	This utility function takes a BLOCK or code reference and "unblocks" it,
361	returning the new coderef. This means that the new coderef will return	671	returning a new coderef. Unblocking means that calling the new coderef
362	immediately without blocking, returning nothing, while the original code	672	will return immediately without blocking, returning nothing, while the
363	ref will be called (with parameters) from within its own coroutine.	673	original code ref will be called (with parameters) from within another
		674	coro.
364		675
365	The reason this fucntion exists is that many event libraries (such as the	676	The reason this function exists is that many event libraries (such as
366	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form	677	the venerable L<Event\|Event> module) are not thread-safe (a weaker form
367	of thread-safety). This means you must not block within event callbacks,	678	of reentrancy). This means you must not block within event callbacks,
368	otherwise you might suffer from crashes or worse.	679	otherwise you might suffer from crashes or worse. The only event library
		680	currently known that is safe to use without C<unblock_sub> is L<EV> (but
		681	you might still run into deadlocks if all event loops are blocked).
		682
		683	Coro will try to catch you when you block in the event loop
		684	("FATAL:$Coro::IDLE blocked itself"), but this is just best effort and
		685	only works when you do not run your own event loop.
369		686
370	This function allows your callbacks to block by executing them in another	687	This function allows your callbacks to block by executing them in another
371	coroutine where it is safe to block. One example where blocking is handy	688	coro where it is safe to block. One example where blocking is handy
372	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to	689	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
373	disk.	690	disk, for example.
374		691
375	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when	692	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
376	creating event callbacks that want to block.	693	creating event callbacks that want to block.
377		694
378	=cut	695	If your handler does not plan to block (e.g. simply sends a message to
		696	another coro, or puts some other coro into the ready queue), there is
		697	no reason to use C<unblock_sub>.
379		698
380	our @unblock_pool;	699	Note that you also need to use C<unblock_sub> for any other callbacks that
		700	are indirectly executed by any C-based event loop. For example, when you
		701	use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it
		702	provides callbacks that are the result of some event callback, then you
		703	must not block either, or use C<unblock_sub>.
		704
		705	=cut
		706
381	our @unblock_queue;	707	our @unblock_queue;
382	our $UNBLOCK_POOL_SIZE = 2;
383		708
384	sub unblock_handler_ {	709	# we create a special coro because we want to cede,
385	while () {	710	# to reduce pressure on the coro pool (because most callbacks
386	my ($cb, @arg) = @{ delete $Coro::current->{arg} };	711	# return immediately and can be reused) and because we cannot cede
387	$cb->(@arg);	712	# inside an event callback.
388
389	last if @unblock_pool >= $UNBLOCK_POOL_SIZE;
390	push @unblock_pool, $Coro::current;
391	schedule;
392	}
393	}
394
395	our $unblock_scheduler = async {	713	our $unblock_scheduler = new Coro sub {
396	while () {	714	while () {
397	while (my $cb = pop @unblock_queue) {	715	while (my $cb = pop @unblock_queue) {
398	my $handler = (pop @unblock_pool or new Coro \&unblock_handler_);	716	&async_pool (@$cb);
399	$handler->{arg} = $cb;	717
400	$handler->ready;	718	# for short-lived callbacks, this reduces pressure on the coro pool
		719	# as the chance is very high that the async_poll coro will be back
		720	# in the idle state when cede returns
401	cede;	721	cede;
402	}	722	}
403		723	schedule; # sleep well
404	schedule;
405	}	724	}
406	};	725	};
		726	$unblock_scheduler->{desc} = "[unblock_sub scheduler]";
407		727
408	sub unblock_sub(&) {	728	sub unblock_sub(&) {
409	my $cb = shift;	729	my $cb = shift;
410		730
411	sub {	731	sub {
412	push @unblock_queue, [$cb, @_];	732	unshift @unblock_queue, [$cb, @_];
413	$unblock_scheduler->ready;	733	$unblock_scheduler->ready;
414	}	734	}
415	}	735	}
416		736
		737	=item $cb = rouse_cb
		738
		739	Create and return a "rouse callback". That's a code reference that,
		740	when called, will remember a copy of its arguments and notify the owner
		741	coro of the callback.
		742
		743	See the next function.
		744
		745	=item @args = rouse_wait [$cb]
		746
		747	Wait for the specified rouse callback (or the last one that was created in
		748	this coro).
		749
		750	As soon as the callback is invoked (or when the callback was invoked
		751	before C<rouse_wait>), it will return the arguments originally passed to
		752	the rouse callback. In scalar context, that means you get the I<last>
		753	argument, just as if C<rouse_wait> had a C<return ($a1, $a2, $a3...)>
		754	statement at the end.
		755
		756	See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example.
		757
417	=back	758	=back
418		759
419	=cut	760	=cut
420		761
421	1;	762	1;
422		763
		764	=head1 HOW TO WAIT FOR A CALLBACK
		765
		766	It is very common for a coro to wait for some callback to be
		767	called. This occurs naturally when you use coro in an otherwise
		768	event-based program, or when you use event-based libraries.
		769
		770	These typically register a callback for some event, and call that callback
		771	when the event occured. In a coro, however, you typically want to
		772	just wait for the event, simplyifying things.
		773
		774	For example C<< AnyEvent->child >> registers a callback to be called when
		775	a specific child has exited:
		776
		777	my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... });
		778
		779	But from within a coro, you often just want to write this:
		780
		781	my $status = wait_for_child $pid;
		782
		783	Coro offers two functions specifically designed to make this easy,
		784	C<Coro::rouse_cb> and C<Coro::rouse_wait>.
		785
		786	The first function, C<rouse_cb>, generates and returns a callback that,
		787	when invoked, will save its arguments and notify the coro that
		788	created the callback.
		789
		790	The second function, C<rouse_wait>, waits for the callback to be called
		791	(by calling C<schedule> to go to sleep) and returns the arguments
		792	originally passed to the callback.
		793
		794	Using these functions, it becomes easy to write the C<wait_for_child>
		795	function mentioned above:
		796
		797	sub wait_for_child($) {
		798	my ($pid) = @_;
		799
		800	my $watcher = AnyEvent->child (pid => $pid, cb => Coro::rouse_cb);
		801
		802	my ($rpid, $rstatus) = Coro::rouse_wait;
		803	$rstatus
		804	}
		805
		806	In the case where C<rouse_cb> and C<rouse_wait> are not flexible enough,
		807	you can roll your own, using C<schedule>:
		808
		809	sub wait_for_child($) {
		810	my ($pid) = @_;
		811
		812	# store the current coro in $current,
		813	# and provide result variables for the closure passed to ->child
		814	my $current = $Coro::current;
		815	my ($done, $rstatus);
		816
		817	# pass a closure to ->child
		818	my $watcher = AnyEvent->child (pid => $pid, cb => sub {
		819	$rstatus = $_[1]; # remember rstatus
		820	$done = 1; # mark $rstatus as valud
		821	});
		822
		823	# wait until the closure has been called
		824	schedule while !$done;
		825
		826	$rstatus
		827	}
		828
		829
423	=head1 BUGS/LIMITATIONS	830	=head1 BUGS/LIMITATIONS
424		831
425	- you must make very sure that no coro is still active on global	832	=over 4
426	destruction. very bad things might happen otherwise (usually segfaults).
427		833
		834	=item fork with pthread backend
		835
		836	When Coro is compiled using the pthread backend (which isn't recommended
		837	but required on many BSDs as their libcs are completely broken), then
		838	coro will not survive a fork. There is no known workaround except to
		839	fix your libc and use a saner backend.
		840
		841	=item perl process emulation ("threads")
		842
428	- this module is not thread-safe. You should only ever use this module	843	This module is not perl-pseudo-thread-safe. You should only ever use this
429	from the same thread (this requirement might be losened in the future	844	module from the first thread (this requirement might be removed in the
430	to allow per-thread schedulers, but Coro::State does not yet allow	845	future to allow per-thread schedulers, but Coro::State does not yet allow
431	this).	846	this). I recommend disabling thread support and using processes, as having
		847	the windows process emulation enabled under unix roughly halves perl
		848	performance, even when not used.
		849
		850	=item coro switching is not signal safe
		851
		852	You must not switch to another coro from within a signal handler (only
		853	relevant with %SIG - most event libraries provide safe signals), I<unless>
		854	you are sure you are not interrupting a Coro function.
		855
		856	That means you I<MUST NOT> call any function that might "block" the
		857	current coro - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or
		858	anything that calls those. Everything else, including calling C<ready>,
		859	works.
		860
		861	=back
		862
		863
		864	=head1 WINDOWS PROCESS EMULATION
		865
		866	A great many people seem to be confused about ithreads (for example, Chip
		867	Salzenberg called me unintelligent, incapable, stupid and gullible,
		868	while in the same mail making rather confused statements about perl
		869	ithreads (for example, that memory or files would be shared), showing his
		870	lack of understanding of this area - if it is hard to understand for Chip,
		871	it is probably not obvious to everybody).
		872
		873	What follows is an ultra-condensed version of my talk about threads in
		874	scripting languages given on the perl workshop 2009:
		875
		876	The so-called "ithreads" were originally implemented for two reasons:
		877	first, to (badly) emulate unix processes on native win32 perls, and
		878	secondly, to replace the older, real thread model ("5.005-threads").
		879
		880	It does that by using threads instead of OS processes. The difference
		881	between processes and threads is that threads share memory (and other
		882	state, such as files) between threads within a single process, while
		883	processes do not share anything (at least not semantically). That
		884	means that modifications done by one thread are seen by others, while
		885	modifications by one process are not seen by other processes.
		886
		887	The "ithreads" work exactly like that: when creating a new ithreads
		888	process, all state is copied (memory is copied physically, files and code
		889	is copied logically). Afterwards, it isolates all modifications. On UNIX,
		890	the same behaviour can be achieved by using operating system processes,
		891	except that UNIX typically uses hardware built into the system to do this
		892	efficiently, while the windows process emulation emulates this hardware in
		893	software (rather efficiently, but of course it is still much slower than
		894	dedicated hardware).
		895
		896	As mentioned before, loading code, modifying code, modifying data
		897	structures and so on is only visible in the ithreads process doing the
		898	modification, not in other ithread processes within the same OS process.
		899
		900	This is why "ithreads" do not implement threads for perl at all, only
		901	processes. What makes it so bad is that on non-windows platforms, you can
		902	actually take advantage of custom hardware for this purpose (as evidenced
		903	by the forks module, which gives you the (i-) threads API, just much
		904	faster).
		905
		906	Sharing data is in the i-threads model is done by transfering data
		907	structures between threads using copying semantics, which is very slow -
		908	shared data simply does not exist. Benchmarks using i-threads which are
		909	communication-intensive show extremely bad behaviour with i-threads (in
		910	fact, so bad that Coro, which cannot take direct advantage of multiple
		911	CPUs, is often orders of magnitude faster because it shares data using
		912	real threads, refer to my talk for details).
		913
		914	As summary, i-threads use threads to implement processes, while
		915	the compatible forks module uses processes to emulate, uhm,
		916	processes. I-threads slow down every perl program when enabled, and
		917	outside of windows, serve no (or little) practical purpose, but
		918	disadvantages every single-threaded Perl program.
		919
		920	This is the reason that I try to avoid the name "ithreads", as it is
		921	misleading as it implies that it implements some kind of thread model for
		922	perl, and prefer the name "windows process emulation", which describes the
		923	actual use and behaviour of it much better.
432		924
433	=head1 SEE ALSO	925	=head1 SEE ALSO
434		926
		927	Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
		928
		929	Debugging: L<Coro::Debug>.
		930
435	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.	931	Support/Utility: L<Coro::Specific>, L<Coro::Util>.
436		932
437	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.	933	Locking and IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>,
		934	L<Coro::SemaphoreSet>, L<Coro::RWLock>.
438		935
439	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.	936	I/O and Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>.
440		937
441	Embedding: L<Coro:MakeMaker>	938	Compatibility with other modules: L<Coro::LWP> (but see also L<AnyEvent::HTTP> for
		939	a better-working alternative), L<Coro::BDB>, L<Coro::Storable>,
		940	L<Coro::Select>.
		941
		942	XS API: L<Coro::MakeMaker>.
		943
		944	Low level Configuration, Thread Environment, Continuations: L<Coro::State>.
442		945
443	=head1 AUTHOR	946	=head1 AUTHOR
444		947
445	Marc Lehmann <schmorp@schmorp.de>	948	Marc Lehmann <schmorp@schmorp.de>
446	http://home.schmorp.de/	949	http://home.schmorp.de/

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Comparing Coro/Coro.pm (file contents): Revision 1.92 by root, Fri Dec 1 03:47:55 2006 UTC vs. Revision 1.282 by root, Sun Dec 26 16:23:51 2010 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.92 by root, Fri Dec 1 03:47:55 2006 UTC vs.
Revision 1.282 by root, Sun Dec 26 16:23:51 2010 UTC