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

Comparing Coro/Coro.pm (file contents):
Revision 1.11 by root, Sun Jul 15 03:24:18 2001 UTC vs.
Revision 1.179 by root, Sat Apr 19 19:06:02 2008 UTC

…		…
2		2
3	Coro - coroutine process abstraction	3	Coro - coroutine process abstraction
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use Coro;	7	use Coro;
8		8
9	async {	9	async {
10	# some asynchronous thread of execution	10	# some asynchronous thread of execution
		11	print "2\n";
		12	cede; # yield back to main
		13	print "4\n";
11	};	14	};
12		15	print "1\n";
13	# alternatively create an async process like this:	16	cede; # yield to coroutine
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	my $lock = new Coro::Semaphore;
19	yield;	22	my $locked;
		23
		24	$lock->down;
		25	$locked = 1;
		26	$lock->up;
20		27
21	=head1 DESCRIPTION	28	=head1 DESCRIPTION
22		29
		30	This module collection manages coroutines. Coroutines are similar
		31	to threads but don't run in parallel at the same time even on SMP
		32	machines. The specific flavor of coroutine used in this module also
		33	guarantees you that it will not switch between coroutines unless
		34	necessary, at easily-identified points in your program, so locking and
		35	parallel access are rarely an issue, making coroutine programming much
		36	safer than threads programming.
		37
		38	(Perl, however, does not natively support real threads but instead does a
		39	very slow and memory-intensive emulation of processes using threads. This
		40	is a performance win on Windows machines, and a loss everywhere else).
		41
		42	In this module, coroutines are defined as "callchain + lexical variables +
		43	@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,
		44	its own set of lexicals and its own set of perls most important global
		45	variables (see L<Coro::State> for more configuration).
		46
23	=cut	47	=cut
24		48
25	package Coro;	49	package Coro;
26		50
		51	use strict;
		52	no warnings "uninitialized";
		53
27	use Coro::State;	54	use Coro::State;
28		55
29	use base Exporter;	56	use base qw(Coro::State Exporter);
30		57
31	$VERSION = 0.04;	58	our $idle; # idle handler
		59	our $main; # main coroutine
		60	our $current; # current coroutine
32		61
33	@EXPORT = qw(async yield schedule);	62	our $VERSION = '4.51';
34	@EXPORT_OK = qw($current);
35		63
36	{	64	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
37	use subs 'async';	65	our %EXPORT_TAGS = (
		66	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
		67	);
		68	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
38		69
39	my @async;	70	=over 4
40		71
41	# this way of handling attributes simply is NOT scalable ;()	72	=item $main
42	sub import {	73
43	Coro->export_to_level(1, @_);	74	This coroutine represents the main program.
44	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};	75
45	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {	76	=cut
46	my ($package, $ref) = (shift, shift);	77
47	my @attrs;	78	$main = new Coro;
48	for (@_) {	79
49	if ($_ eq "Coro") {	80	=item $current (or as function: current)
50	push @async, $ref;	81
51	} else {	82	The current coroutine (the last coroutine switched to). The initial value
52	push @attrs, @_;	83	is C<$main> (of course).
		84
		85	This variable is B<strictly> I<read-only>. It is provided for performance
		86	reasons. If performance is not essential you are encouraged to use the
		87	C<Coro::current> function instead.
		88
		89	=cut
		90
		91	$main->{desc} = "[main::]";
		92
		93	# maybe some other module used Coro::Specific before...
		94	$main->{_specific} = $current->{_specific}
		95	if $current;
		96
		97	_set_current $main;
		98
		99	sub current() { $current }
		100
		101	=item $idle
		102
		103	A callback that is called whenever the scheduler finds no ready coroutines
		104	to run. The default implementation prints "FATAL: deadlock detected" and
		105	exits, because the program has no other way to continue.
		106
		107	This hook is overwritten by modules such as C<Coro::Timer> and
		108	C<Coro::Event> to wait on an external event that hopefully wake up a
		109	coroutine so the scheduler can run it.
		110
		111	Please note that if your callback recursively invokes perl (e.g. for event
		112	handlers), then it must be prepared to be called recursively itself.
		113
		114	=cut
		115
		116	$idle = sub {
		117	require Carp;
		118	Carp::croak ("FATAL: deadlock detected");
		119	};
		120
		121	sub _cancel {
		122	my ($self) = @_;
		123
		124	# free coroutine data and mark as destructed
		125	$self->_destroy
		126	or return;
		127
		128	# call all destruction callbacks
		129	$_->(@{$self->{_status}})
		130	for @{(delete $self->{_on_destroy}) \|\| []};
		131	}
		132
		133	# this coroutine is necessary because a coroutine
		134	# cannot destroy itself.
		135	my @destroy;
		136	my $manager;
		137
		138	$manager = new Coro sub {
		139	while () {
		140	(shift @destroy)->_cancel
		141	while @destroy;
		142
		143	&schedule;
		144	}
		145	};
		146	$manager->desc ("[coro manager]");
		147	$manager->prio (PRIO_MAX);
		148
		149	=back
		150
		151	=head2 STATIC METHODS
		152
		153	Static methods are actually functions that operate on the current coroutine only.
		154
		155	=over 4
		156
		157	=item async { ... } [@args...]
		158
		159	Create a new asynchronous coroutine and return it's coroutine object
		160	(usually unused). When the sub returns the new coroutine is automatically
		161	terminated.
		162
		163	See the C<Coro::State::new> constructor for info about the coroutine
		164	environment in which coroutines run.
		165
		166	Calling C<exit> in a coroutine will do the same as calling exit outside
		167	the coroutine. Likewise, when the coroutine dies, the program will exit,
		168	just as it would in the main program.
		169
		170	# create a new coroutine that just prints its arguments
		171	async {
		172	print "@_\n";
		173	} 1,2,3,4;
		174
		175	=cut
		176
		177	sub async(&@) {
		178	my $coro = new Coro @_;
		179	$coro->ready;
		180	$coro
		181	}
		182
		183	=item async_pool { ... } [@args...]
		184
		185	Similar to C<async>, but uses a coroutine pool, so you should not call
		186	terminate or join (although you are allowed to), and you get a coroutine
		187	that might have executed other code already (which can be good or bad :).
		188
		189	Also, the block is executed in an C<eval> context and a warning will be
		190	issued in case of an exception instead of terminating the program, as
		191	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
		192	will not work in the expected way, unless you call terminate or cancel,
		193	which somehow defeats the purpose of pooling.
		194
		195	The priority will be reset to C<0> after each job, tracing will be
		196	disabled, the description will be reset and the default output filehandle
		197	gets restored, so you can change alkl these. Otherwise the coroutine will
		198	be re-used "as-is": most notably if you change other per-coroutine global
		199	stuff such as C<$/> you need to revert that change, which is most simply
		200	done by using local as in C< local $/ >.
		201
		202	The pool size is limited to 8 idle coroutines (this can be adjusted by
		203	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
		204	required.
		205
		206	If you are concerned about pooled coroutines growing a lot because a
		207	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
		208	{ terminate }> once per second or so to slowly replenish the pool. In
		209	addition to that, when the stacks used by a handler grows larger than 16kb
		210	(adjustable with $Coro::POOL_RSS) it will also exit.
		211
		212	=cut
		213
		214	our $POOL_SIZE = 8;
		215	our $POOL_RSS = 16 * 1024;
		216	our @async_pool;
		217
		218	sub pool_handler {
		219	my $cb;
		220
		221	while () {
		222	eval {
		223	while () {
		224	_pool_1 $cb;
53	}	225	&$cb;
		226	_pool_2 $cb;
		227	&schedule;
54	}	228	}
55	return $old ? $old->($package, $name, @attrs) : @attrs;
56	};	229	};
		230
		231	last if $@ eq "\3async_pool terminate\2\n";
		232	warn $@ if $@;
		233	}
		234	}
		235
		236	sub async_pool(&@) {
		237	# this is also inlined into the unlock_scheduler
		238	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		239
		240	$coro->{_invoke} = [@_];
		241	$coro->ready;
		242
		243	$coro
		244	}
		245
		246	=item schedule
		247
		248	Calls the scheduler. Please note that the current coroutine will not be put
		249	into the ready queue, so calling this function usually means you will
		250	never be called again unless something else (e.g. an event handler) calls
		251	ready.
		252
		253	The canonical way to wait on external events is this:
		254
57	}	255	{
		256	# remember current coroutine
		257	my $current = $Coro::current;
58		258
59	sub INIT {	259	# register a hypothetical event handler
60	async pop @async while @async;	260	on_event_invoke sub {
61	}	261	# wake up sleeping coroutine
62	}	262	$current->ready;
		263	undef $current;
		264	};
63		265
64	=item $main	266	# call schedule until event occurred.
		267	# in case we are woken up for other reasons
		268	# (current still defined), loop.
		269	Coro::schedule while $current;
		270	}
65		271
66	This coroutine represents the main program.
67
68	=cut
69
70	our $main = new Coro;
71
72	=item $current
73
74	The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).
75
76	=cut
77
78	# maybe some other module used Coro::Specific before...
79	if ($current) {
80	$main->{specific} = $current->{specific};
81	}
82
83	our $current = $main;
84
85	=item $idle	272	=item cede
86		273
87	The coroutine to switch to when no other coroutine is running. The default	274	"Cede" to other coroutines. This function puts the current coroutine into the
88	implementation prints "FATAL: deadlock detected" and exits.	275	ready queue and calls C<schedule>, which has the effect of giving up the
		276	current "timeslice" to other coroutines of the same or higher priority.
89		277
90	=cut	278	=item Coro::cede_notself
91		279
92	# should be done using priorities :(	280	Works like cede, but is not exported by default and will cede to any
93	our $idle = new Coro sub {	281	coroutine, regardless of priority, once.
94	print STDERR "FATAL: deadlock detected\n";
95	exit(51);
96	};
97		282
98	# we really need priorities...	283	=item terminate [arg...]
99	my @ready = (); # the ready queue. hehe, rather broken ;)
100		284
101	# static methods. not really.	285	Terminates the current coroutine with the given status values (see L<cancel>).
102		286
		287	=item killall
		288
		289	Kills/terminates/cancels all coroutines except the currently running
		290	one. This is useful after a fork, either in the child or the parent, as
		291	usually only one of them should inherit the running coroutines.
		292
		293	=cut
		294
		295	sub terminate {
		296	$current->cancel (@_);
		297	}
		298
		299	sub killall {
		300	for (Coro::State::list) {
		301	$_->cancel
		302	if $_ != $current && UNIVERSAL::isa $_, "Coro";
		303	}
		304	}
		305
		306	=back
		307
103	=head2 STATIC METHODS	308	=head2 COROUTINE METHODS
104		309
105	Static methods are actually functions that operate on the current process only.	310	These are the methods you can call on coroutine objects.
106		311
107	=over 4	312	=over 4
108		313
109	=item async { ... };	314	=item new Coro \&sub [, @args...]
110		315
111	Create a new asynchronous process and return it's process object
112	(usually unused). When the sub returns the new process is automatically
113	terminated.
114
115	=cut
116
117	sub async(&) {
118	my $pid = new Coro $_[0];
119	$pid->ready;
120	$pid;
121	}
122
123	=item schedule
124
125	Calls the scheduler. Please note that the current process will not be put
126	into the ready queue, so calling this function usually means you will
127	never be called again.
128
129	=cut
130
131	my $prev;
132
133	sub schedule {
134	# should be done using priorities :(
135	($prev, $current) = ($current, shift @ready \|\| $idle);
136	Coro::State::transfer($prev, $current);
137	}
138
139	=item yield
140
141	Yield to other processes. This function puts the current process into the
142	ready queue and calls C<schedule>.
143
144	=cut
145
146	sub yield {
147	$current->ready;
148	&schedule;
149	}
150
151	=item terminate
152
153	Terminates the current process.
154
155	=cut
156
157	sub terminate {
158	&schedule;
159	}
160
161	=back
162
163	# dynamic methods
164
165	=head2 PROCESS METHODS
166
167	These are the methods you can call on process objects.
168
169	=over 4
170
171	=item new Coro \⊂
172
173	Create a new process and return it. When the sub returns the process	316	Create a new coroutine and return it. When the sub returns the coroutine
174	automatically terminates. To start the process you must first put it into	317	automatically terminates as if C<terminate> with the returned values were
		318	called. To make the coroutine run you must first put it into the ready queue
175	the ready queue by calling the ready method.	319	by calling the ready method.
176		320
		321	See C<async> and C<Coro::State::new> for additional info about the
		322	coroutine environment.
		323
177	=cut	324	=cut
		325
		326	sub _run_coro {
		327	terminate &{+shift};
		328	}
178		329
179	sub new {	330	sub new {
180	my $class = shift;	331	my $class = shift;
		332
		333	$class->SUPER::new (\&_run_coro, @_)
		334	}
		335
		336	=item $success = $coroutine->ready
		337
		338	Put the given coroutine into the ready queue (according to it's priority)
		339	and return true. If the coroutine is already in the ready queue, do nothing
		340	and return false.
		341
		342	=item $is_ready = $coroutine->is_ready
		343
		344	Return wether the coroutine is currently the ready queue or not,
		345
		346	=item $coroutine->cancel (arg...)
		347
		348	Terminates the given coroutine and makes it return the given arguments as
		349	status (default: the empty list). Never returns if the coroutine is the
		350	current coroutine.
		351
		352	=cut
		353
		354	sub cancel {
		355	my $self = shift;
		356	$self->{_status} = [@_];
		357
		358	if ($current == $self) {
		359	push @destroy, $self;
		360	$manager->ready;
		361	&schedule while 1;
		362	} else {
		363	$self->_cancel;
		364	}
		365	}
		366
		367	=item $coroutine->join
		368
		369	Wait until the coroutine terminates and return any values given to the
		370	C<terminate> or C<cancel> functions. C<join> can be called concurrently
		371	from multiple coroutines.
		372
		373	=cut
		374
		375	sub join {
		376	my $self = shift;
		377
		378	unless ($self->{_status}) {
		379	my $current = $current;
		380
		381	push @{$self->{_on_destroy}}, sub {
		382	$current->ready;
		383	undef $current;
		384	};
		385
		386	&schedule while $current;
		387	}
		388
		389	wantarray ? @{$self->{_status}} : $self->{_status}[0];
		390	}
		391
		392	=item $coroutine->on_destroy (\&cb)
		393
		394	Registers a callback that is called when this coroutine gets destroyed,
		395	but before it is joined. The callback gets passed the terminate arguments,
		396	if any.
		397
		398	=cut
		399
		400	sub on_destroy {
		401	my ($self, $cb) = @_;
		402
		403	push @{ $self->{_on_destroy} }, $cb;
		404	}
		405
		406	=item $oldprio = $coroutine->prio ($newprio)
		407
		408	Sets (or gets, if the argument is missing) the priority of the
		409	coroutine. Higher priority coroutines get run before lower priority
		410	coroutines. Priorities are small signed integers (currently -4 .. +3),
		411	that you can refer to using PRIO_xxx constants (use the import tag :prio
		412	to get then):
		413
		414	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
		415	3 > 1 > 0 > -1 > -3 > -4
		416
		417	# set priority to HIGH
		418	current->prio(PRIO_HIGH);
		419
		420	The idle coroutine ($Coro::idle) always has a lower priority than any
		421	existing coroutine.
		422
		423	Changing the priority of the current coroutine will take effect immediately,
		424	but changing the priority of coroutines in the ready queue (but not
		425	running) will only take effect after the next schedule (of that
		426	coroutine). This is a bug that will be fixed in some future version.
		427
		428	=item $newprio = $coroutine->nice ($change)
		429
		430	Similar to C<prio>, but subtract the given value from the priority (i.e.
		431	higher values mean lower priority, just as in unix).
		432
		433	=item $olddesc = $coroutine->desc ($newdesc)
		434
		435	Sets (or gets in case the argument is missing) the description for this
		436	coroutine. This is just a free-form string you can associate with a coroutine.
		437
		438	This method simply sets the C<< $coroutine->{desc} >> member to the given string. You
		439	can modify this member directly if you wish.
		440
		441	=item $coroutine->throw ([$scalar])
		442
		443	If C<$throw> is specified and defined, it will be thrown as an exception
		444	inside the coroutine at the next convinient point in time (usually after
		445	it gains control at the next schedule/transfer/cede). Otherwise clears the
		446	exception object.
		447
		448	The exception object will be thrown "as is" with the specified scalar in
		449	C<$@>, i.e. if it is a string, no line number or newline will be appended
		450	(unlike with C<die>).
		451
		452	This can be used as a softer means than C<cancel> to ask a coroutine to
		453	end itself, although there is no guarentee that the exception will lead to
		454	termination, and if the exception isn't caught it might well end the whole
		455	program.
		456
		457	=cut
		458
		459	sub desc {
181	my $proc = $_[0];	460	my $old = $_[0]{desc};
182	bless {	461	$_[0]{desc} = $_[1] if @_ > 1;
183	_coro_state => new Coro::State ($proc ? sub { &$proc; &terminate } : $proc),	462	$old;
184	}, $class;
185	}
186
187	=item $process->ready
188
189	Put the current process into the ready queue.
190
191	=cut
192
193	sub ready {
194	push @ready, $_[0];
195	}	463	}
196		464
197	=back	465	=back
198		466
		467	=head2 GLOBAL FUNCTIONS
		468
		469	=over 4
		470
		471	=item Coro::nready
		472
		473	Returns the number of coroutines that are currently in the ready state,
		474	i.e. that can be switched to. The value C<0> means that the only runnable
		475	coroutine is the currently running one, so C<cede> would have no effect,
		476	and C<schedule> would cause a deadlock unless there is an idle handler
		477	that wakes up some coroutines.
		478
		479	=item my $guard = Coro::guard { ... }
		480
		481	This creates and returns a guard object. Nothing happens until the object
		482	gets destroyed, in which case the codeblock given as argument will be
		483	executed. This is useful to free locks or other resources in case of a
		484	runtime error or when the coroutine gets canceled, as in both cases the
		485	guard block will be executed. The guard object supports only one method,
		486	C<< ->cancel >>, which will keep the codeblock from being executed.
		487
		488	Example: set some flag and clear it again when the coroutine gets canceled
		489	or the function returns:
		490
		491	sub do_something {
		492	my $guard = Coro::guard { $busy = 0 };
		493	$busy = 1;
		494
		495	# do something that requires $busy to be true
		496	}
		497
		498	=cut
		499
		500	sub guard(&) {
		501	bless \(my $cb = $_[0]), "Coro::guard"
		502	}
		503
		504	sub Coro::guard::cancel {
		505	${$_[0]} = sub { };
		506	}
		507
		508	sub Coro::guard::DESTROY {
		509	${$_[0]}->();
		510	}
		511
		512
		513	=item unblock_sub { ... }
		514
		515	This utility function takes a BLOCK or code reference and "unblocks" it,
		516	returning the new coderef. This means that the new coderef will return
		517	immediately without blocking, returning nothing, while the original code
		518	ref will be called (with parameters) from within its own coroutine.
		519
		520	The reason this function exists is that many event libraries (such as the
		521	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		522	of thread-safety). This means you must not block within event callbacks,
		523	otherwise you might suffer from crashes or worse.
		524
		525	This function allows your callbacks to block by executing them in another
		526	coroutine where it is safe to block. One example where blocking is handy
		527	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		528	disk.
		529
		530	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		531	creating event callbacks that want to block.
		532
		533	=cut
		534
		535	our @unblock_queue;
		536
		537	# we create a special coro because we want to cede,
		538	# to reduce pressure on the coro pool (because most callbacks
		539	# return immediately and can be reused) and because we cannot cede
		540	# inside an event callback.
		541	our $unblock_scheduler = new Coro sub {
		542	while () {
		543	while (my $cb = pop @unblock_queue) {
		544	# this is an inlined copy of async_pool
		545	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		546
		547	$coro->{_invoke} = $cb;
		548	$coro->ready;
		549	cede; # for short-lived callbacks, this reduces pressure on the coro pool
		550	}
		551	schedule; # sleep well
		552	}
		553	};
		554	$unblock_scheduler->desc ("[unblock_sub scheduler]");
		555
		556	sub unblock_sub(&) {
		557	my $cb = shift;
		558
		559	sub {
		560	unshift @unblock_queue, [$cb, @_];
		561	$unblock_scheduler->ready;
		562	}
		563	}
		564
		565	=back
		566
199	=cut	567	=cut
200		568
201	1;	569	1;
202		570
		571	=head1 BUGS/LIMITATIONS
		572
		573	- you must make very sure that no coro is still active on global
		574	destruction. very bad things might happen otherwise (usually segfaults).
		575
		576	- this module is not thread-safe. You should only ever use this module
		577	from the same thread (this requirement might be loosened in the future
		578	to allow per-thread schedulers, but Coro::State does not yet allow
		579	this).
		580
203	=head1 SEE ALSO	581	=head1 SEE ALSO
204		582
205	L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,	583	Lower level Configuration, Coroutine Environment: L<Coro::State>.
206	L<Coro::Signal>, L<Coro::State>, L<Coro::Event>.	584
		585	Debugging: L<Coro::Debug>.
		586
		587	Support/Utility: L<Coro::Specific>, L<Coro::Util>.
		588
		589	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
		590
		591	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>.
		592
		593	Compatibility: L<Coro::LWP>, L<Coro::Storable>, L<Coro::Select>.
		594
		595	Embedding: L<Coro::MakeMaker>.
207		596
208	=head1 AUTHOR	597	=head1 AUTHOR
209		598
210	Marc Lehmann <pcg@goof.com>	599	Marc Lehmann <schmorp@schmorp.de>
211	http://www.goof.com/pcg/marc/	600	http://home.schmorp.de/
212		601
213	=cut	602	=cut
214		603

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Comparing Coro/Coro.pm (file contents): Revision 1.11 by root, Sun Jul 15 03:24:18 2001 UTC vs. Revision 1.179 by root, Sat Apr 19 19:06:02 2008 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.11 by root, Sun Jul 15 03:24:18 2001 UTC vs.
Revision 1.179 by root, Sat Apr 19 19:06:02 2008 UTC