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

Comparing Coro/Coro.pm (file contents):
Revision 1.29 by root, Sat Aug 11 00:37:31 2001 UTC vs.
Revision 1.129 by root, Wed Sep 19 22:33:08 2007 UTC

…		…
8		8
9	async {	9	async {
10	# some asynchronous thread of execution	10	# some asynchronous thread of execution
11	};	11	};
12		12
13	# alternatively create an async process like this:	13	# alternatively create an async coroutine like this:
14		14
15	sub some_func : Coro {	15	sub some_func : Coro {
16	# some more async code	16	# some more async code
17	}	17	}
18		18
19	cede;	19	cede;
20		20
21	=head1 DESCRIPTION	21	=head1 DESCRIPTION
22		22
23	This module collection manages coroutines. Coroutines are similar to	23	This module collection manages coroutines. Coroutines are similar
24	Threads but don't run in parallel.	24	to threads but don't run in parallel at the same time even on SMP
		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.
25		30
26	This module is still experimental, see the BUGS section below.	31	(Perl, however, does not natively support real threads but instead does a
		32	very slow and memory-intensive emulation of processes using threads. This
		33	is a performance win on Windows machines, and a loss everywhere else).
27		34
28	In this module, coroutines are defined as "callchain + lexical variables	35	In this module, coroutines are defined as "callchain + lexical variables +
29	+ @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own	36	@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,
30	callchain, it's own set of lexicals and it's own set of perl's most	37	its own set of lexicals and its own set of perls most important global
31	important global variables.	38	variables.
32		39
33	=cut	40	=cut
34		41
35	package Coro;	42	package Coro;
36		43
		44	use strict;
		45	no warnings "uninitialized";
		46
37	use Coro::State;	47	use Coro::State;
38		48
39	use base Exporter;	49	use base qw(Coro::State Exporter);
40		50
41	$VERSION = 0.45;	51	our $idle; # idle handler
		52	our $main; # main coroutine
		53	our $current; # current coroutine
42		54
		55	our $VERSION = '3.7';
		56
43	@EXPORT = qw(async cede schedule terminate current);	57	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
44	@EXPORT_OK = qw($current);	58	our %EXPORT_TAGS = (
		59	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
		60	);
		61	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
45		62
46	{	63	{
47	my @async;	64	my @async;
48	my $init;	65	my $init;
49		66
50	# this way of handling attributes simply is NOT scalable ;()	67	# this way of handling attributes simply is NOT scalable ;()
51	sub import {	68	sub import {
		69	no strict 'refs';
		70
52	Coro->export_to_level(1, @_);	71	Coro->export_to_level (1, @_);
		72
53	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};	73	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
54	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {	74	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
55	my ($package, $ref) = (shift, shift);	75	my ($package, $ref) = (shift, shift);
56	my @attrs;	76	my @attrs;
57	for (@_) {	77	for (@_) {
…		…
72	};	92	};
73	}	93	}
74		94
75	}	95	}
76		96
		97	=over 4
		98
77	=item $main	99	=item $main
78		100
79	This coroutine represents the main program.	101	This coroutine represents the main program.
80		102
81	=cut	103	=cut
82		104
83	our $main = new Coro;	105	$main = new Coro;
84		106
85	=item $current (or as function: current)	107	=item $current (or as function: current)
86		108
87	The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).	109	The current coroutine (the last coroutine switched to). The initial value
		110	is C<$main> (of course).
		111
		112	This variable is B<strictly> I<read-only>. It is provided for performance
		113	reasons. If performance is not essential you are encouraged to use the
		114	C<Coro::current> function instead.
88		115
89	=cut	116	=cut
90		117
91	# maybe some other module used Coro::Specific before...	118	# maybe some other module used Coro::Specific before...
92	if ($current) {
93	$main->{specific} = $current->{specific};	119	$main->{specific} = $current->{specific}
94	}	120	if $current;
95		121
96	our $current = $main;	122	_set_current $main;
97		123
98	sub current() { $current }	124	sub current() { $current }
99		125
100	=item $idle	126	=item $idle
101		127
102	The coroutine to switch to when no other coroutine is running. The default	128	A callback that is called whenever the scheduler finds no ready coroutines
103	implementation prints "FATAL: deadlock detected" and exits.	129	to run. The default implementation prints "FATAL: deadlock detected" and
		130	exits, because the program has no other way to continue.
104		131
105	=cut	132	This hook is overwritten by modules such as C<Coro::Timer> and
		133	C<Coro::Event> to wait on an external event that hopefully wake up a
		134	coroutine so the scheduler can run it.
106		135
107	# should be done using priorities :(	136	Please note that if your callback recursively invokes perl (e.g. for event
108	our $idle = new Coro sub {	137	handlers), then it must be prepared to be called recursively.
109	print STDERR "FATAL: deadlock detected\n";	138
110	exit(51);	139	=cut
		140
		141	$idle = sub {
		142	require Carp;
		143	Carp::croak ("FATAL: deadlock detected");
111	};	144	};
		145
		146	sub _cancel {
		147	my ($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	}
112		157
113	# this coroutine is necessary because a coroutine	158	# this coroutine is necessary because a coroutine
114	# cannot destroy itself.	159	# cannot destroy itself.
115	my @destroy;	160	my @destroy;
		161	my $manager;
		162
116	my $manager = new Coro sub {	163	$manager = new Coro sub {
		164	$current->desc ("[coro manager]");
		165
117	while() {	166	while () {
118	delete ((pop @destroy)->{_coro_state}) while @destroy;	167	(shift @destroy)->_cancel
		168	while @destroy;
		169
119	&schedule;	170	&schedule;
120	}	171	}
121	};	172	};
122		173
123	# we really need priorities...	174	$manager->prio (PRIO_MAX);
124	my @ready; # the ready queue. hehe, rather broken ;)
125		175
126	# static methods. not really.	176	# static methods. not really.
127		177
		178	=back
		179
128	=head2 STATIC METHODS	180	=head2 STATIC METHODS
129		181
130	Static methods are actually functions that operate on the current process only.	182	Static methods are actually functions that operate on the current coroutine only.
131		183
132	=over 4	184	=over 4
133		185
134	=item async { ... } [@args...]	186	=item async { ... } [@args...]
135		187
136	Create a new asynchronous process and return it's process object	188	Create a new asynchronous coroutine and return it's coroutine object
137	(usually unused). When the sub returns the new process is automatically	189	(usually unused). When the sub returns the new coroutine is automatically
138	terminated.	190	terminated.
		191
		192	Calling C<exit> in a coroutine will do the same as calling exit outside
		193	the coroutine. Likewise, when the coroutine dies, the program will exit,
		194	just as it would in the main program.
139		195
140	# create a new coroutine that just prints its arguments	196	# create a new coroutine that just prints its arguments
141	async {	197	async {
142	print "@_\n";	198	print "@_\n";
143	} 1,2,3,4;	199	} 1,2,3,4;
144		200
145	The coderef you submit MUST NOT be a closure that refers to variables
146	in an outer scope. This does NOT work. Pass arguments into it instead.
147
148	=cut	201	=cut
149		202
150	sub async(&@) {	203	sub async(&@) {
151	my $pid = new Coro @_;	204	my $coro = new Coro @_;
152	$manager->ready; # this ensures that the stack is cloned from the manager
153	$pid->ready;	205	$coro->ready;
154	$pid;	206	$coro
		207	}
		208
		209	=item async_pool { ... } [@args...]
		210
		211	Similar to C<async>, but uses a coroutine pool, so you should not call
		212	terminate or join (although you are allowed to), and you get a coroutine
		213	that might have executed other code already (which can be good or bad :).
		214
		215	Also, the block is executed in an C<eval> context and a warning will be
		216	issued in case of an exception instead of terminating the program, as
		217	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
		218	will not work in the expected way, unless you call terminate or cancel,
		219	which somehow defeats the purpose of pooling.
		220
		221	The priority will be reset to C<0> after each job, otherwise the coroutine
		222	will be re-used "as-is".
		223
		224	The pool size is limited to 8 idle coroutines (this can be adjusted by
		225	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
		226	required.
		227
		228	If you are concerned about pooled coroutines growing a lot because a
		229	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool {
		230	terminate }> once per second or so to slowly replenish the pool.
		231
		232	=cut
		233
		234	our $POOL_SIZE = 8;
		235	our @pool;
		236
		237	sub pool_handler {
		238	while () {
		239	$current->{desc} = "[async_pool]";
		240
		241	eval {
		242	my ($cb, @arg) = @{ delete $current->{_invoke} or return };
		243	$cb->(@arg);
		244	};
		245	warn $@ if $@;
		246
		247	last if @pool >= $POOL_SIZE;
		248
		249	push @pool, $current;
		250	$current->{desc} = "[async_pool idle]";
		251	$current->save (Coro::State::SAVE_DEF);
		252	$current->prio (0);
		253	schedule;
		254	}
		255	}
		256
		257	sub async_pool(&@) {
		258	# this is also inlined into the unlock_scheduler
		259	my $coro = (pop @pool) \|\| new Coro \&pool_handler;;
		260
		261	$coro->{_invoke} = [@_];
		262	$coro->ready;
		263
		264	$coro
155	}	265	}
156		266
157	=item schedule	267	=item schedule
158		268
159	Calls the scheduler. Please note that the current process will not be put	269	Calls the scheduler. Please note that the current coroutine will not be put
160	into the ready queue, so calling this function usually means you will	270	into the ready queue, so calling this function usually means you will
161	never be called again.	271	never be called again unless something else (e.g. an event handler) calls
		272	ready.
162		273
163	=cut	274	The canonical way to wait on external events is this:
164		275
165	my $prev;	276	{
		277	# remember current coroutine
		278	my $current = $Coro::current;
166		279
167	sub schedule {	280	# register a hypothetical event handler
168	# should be done using priorities :(	281	on_event_invoke sub {
169	($prev, $current) = ($current, shift @ready \|\| $idle);	282	# wake up sleeping coroutine
170	Coro::State::transfer($prev, $current);	283	$current->ready;
171	}	284	undef $current;
		285	};
		286
		287	# call schedule until event occurred.
		288	# in case we are woken up for other reasons
		289	# (current still defined), loop.
		290	Coro::schedule while $current;
		291	}
172		292
173	=item cede	293	=item cede
174		294
175	"Cede" to other processes. This function puts the current process into the	295	"Cede" to other coroutines. This function puts the current coroutine into the
176	ready queue and calls C<schedule>, which has the effect of giving up the	296	ready queue and calls C<schedule>, which has the effect of giving up the
177	current "timeslice" to other coroutines of the same or higher priority.	297	current "timeslice" to other coroutines of the same or higher priority.
178		298
179	=cut	299	Returns true if at least one coroutine switch has happened.
180		300
181	sub cede {	301	=item Coro::cede_notself
182	$current->ready;
183	&schedule;
184	}
185		302
		303	Works like cede, but is not exported by default and will cede to any
		304	coroutine, regardless of priority, once.
		305
		306	Returns true if at least one coroutine switch has happened.
		307
186	=item terminate	308	=item terminate [arg...]
187		309
188	Terminates the current process.	310	Terminates the current coroutine with the given status values (see L<cancel>).
189
190	Future versions of this function will allow result arguments.
191		311
192	=cut	312	=cut
193		313
194	sub terminate {	314	sub terminate {
195	$current->cancel;	315	$current->cancel (@_);
196	&schedule;
197	die; # NORETURN
198	}	316	}
199		317
200	=back	318	=back
201		319
202	# dynamic methods	320	# dynamic methods
203		321
204	=head2 PROCESS METHODS	322	=head2 COROUTINE METHODS
205		323
206	These are the methods you can call on process objects.	324	These are the methods you can call on coroutine objects.
207		325
208	=over 4	326	=over 4
209		327
210	=item new Coro \&sub [, @args...]	328	=item new Coro \&sub [, @args...]
211		329
212	Create a new process and return it. When the sub returns the process	330	Create a new coroutine and return it. When the sub returns the coroutine
213	automatically terminates. To start the process you must first put it into	331	automatically terminates as if C<terminate> with the returned values were
		332	called. To make the coroutine run you must first put it into the ready queue
214	the ready queue by calling the ready method.	333	by calling the ready method.
215		334
216	The coderef you submit MUST NOT be a closure that refers to variables	335	See C<async> for additional discussion.
217	in an outer scope. This does NOT work. Pass arguments into it instead.
218		336
219	=cut	337	=cut
220		338
221	sub _newcoro {	339	sub _run_coro {
222	terminate &{+shift};	340	terminate &{+shift};
223	}	341	}
224		342
225	sub new {	343	sub new {
226	my $class = shift;	344	my $class = shift;
227	bless {
228	_coro_state => (new Coro::State $_[0] && \&_newcoro, @_),
229	}, $class;
230	}
231		345
232	=item $process->ready	346	$class->SUPER::new (\&_run_coro, @_)
233
234	Put the current process into the ready queue.
235
236	=cut
237
238	sub ready {
239	push @ready, $_[0];
240	}	347	}
241		348
242	=item $process->cancel	349	=item $success = $coroutine->ready
243		350
244	Like C<terminate>, but terminates the specified process instead.	351	Put the given coroutine into the ready queue (according to it's priority)
		352	and return true. If the coroutine is already in the ready queue, do nothing
		353	and return false.
		354
		355	=item $is_ready = $coroutine->is_ready
		356
		357	Return wether the coroutine is currently the ready queue or not,
		358
		359	=item $coroutine->cancel (arg...)
		360
		361	Terminates the given coroutine and makes it return the given arguments as
		362	status (default: the empty list). Never returns if the coroutine is the
		363	current coroutine.
245		364
246	=cut	365	=cut
247		366
248	sub cancel {	367	sub cancel {
		368	my $self = shift;
		369	$self->{status} = [@_];
		370
		371	if ($current == $self) {
249	push @destroy, $_[0];	372	push @destroy, $self;
250	$manager->ready;	373	$manager->ready;
		374	&schedule while 1;
		375	} else {
		376	$self->_cancel;
		377	}
		378	}
		379
		380	=item $coroutine->join
		381
		382	Wait until the coroutine terminates and return any values given to the
		383	C<terminate> or C<cancel> functions. C<join> can be called multiple times
		384	from multiple coroutine.
		385
		386	=cut
		387
		388	sub join {
		389	my $self = shift;
		390
		391	unless ($self->{status}) {
		392	my $current = $current;
		393
		394	push @{$self->{destroy_cb}}, sub {
		395	$current->ready;
		396	undef $current;
		397	};
		398
		399	&schedule while $current;
		400	}
		401
		402	wantarray ? @{$self->{status}} : $self->{status}[0];
		403	}
		404
		405	=item $coroutine->on_destroy (\&cb)
		406
		407	Registers a callback that is called when this coroutine gets destroyed,
		408	but before it is joined. The callback gets passed the terminate arguments,
		409	if any.
		410
		411	=cut
		412
		413	sub on_destroy {
		414	my ($self, $cb) = @_;
		415
		416	push @{ $self->{destroy_cb} }, $cb;
		417	}
		418
		419	=item $oldprio = $coroutine->prio ($newprio)
		420
		421	Sets (or gets, if the argument is missing) the priority of the
		422	coroutine. Higher priority coroutines get run before lower priority
		423	coroutines. Priorities are small signed integers (currently -4 .. +3),
		424	that you can refer to using PRIO_xxx constants (use the import tag :prio
		425	to get then):
		426
		427	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
		428	3 > 1 > 0 > -1 > -3 > -4
		429
		430	# set priority to HIGH
		431	current->prio(PRIO_HIGH);
		432
		433	The idle coroutine ($Coro::idle) always has a lower priority than any
		434	existing coroutine.
		435
		436	Changing the priority of the current coroutine will take effect immediately,
		437	but changing the priority of coroutines in the ready queue (but not
		438	running) will only take effect after the next schedule (of that
		439	coroutine). This is a bug that will be fixed in some future version.
		440
		441	=item $newprio = $coroutine->nice ($change)
		442
		443	Similar to C<prio>, but subtract the given value from the priority (i.e.
		444	higher values mean lower priority, just as in unix).
		445
		446	=item $olddesc = $coroutine->desc ($newdesc)
		447
		448	Sets (or gets in case the argument is missing) the description for this
		449	coroutine. This is just a free-form string you can associate with a coroutine.
		450
		451	=cut
		452
		453	sub desc {
		454	my $old = $_[0]{desc};
		455	$_[0]{desc} = $_[1] if @_ > 1;
		456	$old;
251	}	457	}
252		458
253	=back	459	=back
254		460
		461	=head2 GLOBAL FUNCTIONS
		462
		463	=over 4
		464
		465	=item Coro::nready
		466
		467	Returns the number of coroutines that are currently in the ready state,
		468	i.e. that can be switched to. The value C<0> means that the only runnable
		469	coroutine is the currently running one, so C<cede> would have no effect,
		470	and C<schedule> would cause a deadlock unless there is an idle handler
		471	that wakes up some coroutines.
		472
		473	=item my $guard = Coro::guard { ... }
		474
		475	This creates and returns a guard object. Nothing happens until the object
		476	gets destroyed, in which case the codeblock given as argument will be
		477	executed. This is useful to free locks or other resources in case of a
		478	runtime error or when the coroutine gets canceled, as in both cases the
		479	guard block will be executed. The guard object supports only one method,
		480	C<< ->cancel >>, which will keep the codeblock from being executed.
		481
		482	Example: set some flag and clear it again when the coroutine gets canceled
		483	or the function returns:
		484
		485	sub do_something {
		486	my $guard = Coro::guard { $busy = 0 };
		487	$busy = 1;
		488
		489	# do something that requires $busy to be true
		490	}
		491
		492	=cut
		493
		494	sub guard(&) {
		495	bless \(my $cb = $_[0]), "Coro::guard"
		496	}
		497
		498	sub Coro::guard::cancel {
		499	${$_[0]} = sub { };
		500	}
		501
		502	sub Coro::guard::DESTROY {
		503	${$_[0]}->();
		504	}
		505
		506
		507	=item unblock_sub { ... }
		508
		509	This utility function takes a BLOCK or code reference and "unblocks" it,
		510	returning the new coderef. This means that the new coderef will return
		511	immediately without blocking, returning nothing, while the original code
		512	ref will be called (with parameters) from within its own coroutine.
		513
		514	The reason this function exists is that many event libraries (such as the
		515	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		516	of thread-safety). This means you must not block within event callbacks,
		517	otherwise you might suffer from crashes or worse.
		518
		519	This function allows your callbacks to block by executing them in another
		520	coroutine where it is safe to block. One example where blocking is handy
		521	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		522	disk.
		523
		524	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		525	creating event callbacks that want to block.
		526
		527	=cut
		528
		529	our @unblock_queue;
		530
		531	# we create a special coro because we want to cede,
		532	# to reduce pressure on the coro pool (because most callbacks
		533	# return immediately and can be reused) and because we cannot cede
		534	# inside an event callback.
		535	our $unblock_scheduler = async {
		536	$current->desc ("[unblock_sub scheduler]");
		537	while () {
		538	while (my $cb = pop @unblock_queue) {
		539	# this is an inlined copy of async_pool
		540	my $coro = (pop @pool or new Coro \&pool_handler);
		541
		542	$coro->{_invoke} = $cb;
		543	$coro->ready;
		544	cede; # for short-lived callbacks, this reduces pressure on the coro pool
		545	}
		546	schedule; # sleep well
		547	}
		548	};
		549
		550	sub unblock_sub(&) {
		551	my $cb = shift;
		552
		553	sub {
		554	unshift @unblock_queue, [$cb, @_];
		555	$unblock_scheduler->ready;
		556	}
		557	}
		558
		559	=back
		560
255	=cut	561	=cut
256		562
257	1;	563	1;
258		564
259	=head1 BUGS/LIMITATIONS	565	=head1 BUGS/LIMITATIONS
260		566
261	- could be faster, especially when the core would introduce special	567	- you must make very sure that no coro is still active on global
262	support for coroutines (like it does for threads).	568	destruction. very bad things might happen otherwise (usually segfaults).
263	- there is still a memleak on coroutine termination that I could not	569
264	identify. Could be as small as a single SV.
265	- this module is not well-tested.
266	- if variables or arguments "disappear" (become undef) or become
267	corrupted please contact the author so he cen iron out the
268	remaining bugs.
269	- this module is not thread-safe. You must only ever use this module from	570	- this module is not thread-safe. You should only ever use this module
270	the same thread (this requirement might be loosened in the future to	571	from the same thread (this requirement might be loosened in the future
271	allow per-thread schedulers, but Coro::State does not yet allow this).	572	to allow per-thread schedulers, but Coro::State does not yet allow
		573	this).
272		574
273	=head1 SEE ALSO	575	=head1 SEE ALSO
274		576
275	L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,	577	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.
276	L<Coro::Signal>, L<Coro::State>, L<Coro::Event>, L<Coro::RWLock>,	578
277	L<Coro::Handle>, L<Coro::Socket>.	579	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
		580
		581	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.
		582
		583	Embedding: L<Coro:MakeMaker>
278		584
279	=head1 AUTHOR	585	=head1 AUTHOR
280		586
281	Marc Lehmann <pcg@goof.com>	587	Marc Lehmann <schmorp@schmorp.de>
282	http://www.goof.com/pcg/marc/	588	http://home.schmorp.de/
283		589
284	=cut	590	=cut
285		591

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Comparing Coro/Coro.pm (file contents): Revision 1.29 by root, Sat Aug 11 00:37:31 2001 UTC vs. Revision 1.129 by root, Wed Sep 19 22:33:08 2007 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.29 by root, Sat Aug 11 00:37:31 2001 UTC vs.
Revision 1.129 by root, Wed Sep 19 22:33:08 2007 UTC