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

Comparing Coro/Coro.pm (file contents):
Revision 1.20 by root, Sat Jul 21 18:21:45 2001 UTC vs.
Revision 1.104 by root, Thu Jan 4 23:49:27 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	yield;	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 use din this module also
		26	guarentees 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), that is, a coroutine has it's own callchain, it's	36	@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,
30	own set of lexicals and it's own set of perl's most important global	37	its own set of lexicals and its own set of perls most important global
31	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 = 0.10;	51	our $idle; # idle handler
		52	our $main; # main coroutine
		53	our $current; # current coroutine
42		54
		55	our $VERSION = '3.3';
		56
43	@EXPORT = qw(async yield schedule terminate current);	57	our @EXPORT = qw(async cede schedule terminate current unblock_sub);
44	@EXPORT_OK = qw($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;
		65	my $init;
48		66
49	# this way of handling attributes simply is NOT scalable ;()	67	# this way of handling attributes simply is NOT scalable ;()
50	sub import {	68	sub import {
		69	no strict 'refs';
		70
51	Coro->export_to_level(1, @_);	71	Coro->export_to_level (1, @_);
		72
52	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};	73	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
53	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {	74	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
54	my ($package, $ref) = (shift, shift);	75	my ($package, $ref) = (shift, shift);
55	my @attrs;	76	my @attrs;
56	for (@_) {	77	for (@_) {
57	if ($_ eq "Coro") {	78	if ($_ eq "Coro") {
58	push @async, $ref;	79	push @async, $ref;
		80	unless ($init++) {
		81	eval q{
		82	sub INIT {
		83	&async(pop @async) while @async;
		84	}
		85	};
		86	}
59	} else {	87	} else {
60	push @attrs, $_;	88	push @attrs, $_;
61	}	89	}
62	}	90	}
63	return $old ? $old->($package, $ref, @attrs) : @attrs;	91	return $old ? $old->($package, $ref, @attrs) : @attrs;
64	};	92	};
65	}	93	}
66		94
67	sub INIT {
68	&async(pop @async) while @async;
69	}
70	}	95	}
		96
		97	=over 4
71		98
72	=item $main	99	=item $main
73		100
74	This coroutine represents the main program.	101	This coroutine represents the main program.
75		102
76	=cut	103	=cut
77		104
78	our $main = new Coro;	105	$main = new Coro;
79		106
80	=item $current (or as function: current)	107	=item $current (or as function: current)
81		108
82	The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).	109	The current coroutine (the last coroutine switched to). The initial value
		110	is C<$main> (of course).
		111
		112	This variable is B<strictly> I<read-only>. It is provided for performance
		113	reasons. If performance is not essentiel you are encouraged to use the
		114	C<Coro::current> function instead.
83		115
84	=cut	116	=cut
85		117
86	# maybe some other module used Coro::Specific before...	118	# maybe some other module used Coro::Specific before...
87	if ($current) {
88	$main->{specific} = $current->{specific};	119	$main->{specific} = $current->{specific}
89	}	120	if $current;
90		121
91	our $current = $main;	122	_set_current $main;
92		123
93	sub current() { $current }	124	sub current() { $current }
94		125
95	=item $idle	126	=item $idle
96		127
97	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
98	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.
99		131
100	=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.
101		135
102	# should be done using priorities :(	136	Please note that if your callback recursively invokes perl (e.g. for event
103	our $idle = new Coro sub {	137	handlers), then it must be prepared to be called recursively.
104	print STDERR "FATAL: deadlock detected\n";	138
105	exit(51);	139	=cut
		140
		141	$idle = sub {
		142	require Carp;
		143	Carp::croak ("FATAL: deadlock detected");
106	};	144	};
107		145
108	# we really need priorities...	146	sub _cancel {
109	my @ready; # the ready queue. hehe, rather broken ;)	147	my ($self) = @_;
		148
		149	# free coroutine data and mark as destructed
		150	$self->_destroy
		151	or return;
		152
		153	# call all destruction callbacks
		154	$_->(@{$self->{status}})
		155	for @{(delete $self->{destroy_cb}) \|\| []};
		156	}
		157
		158	# this coroutine is necessary because a coroutine
		159	# cannot destroy itself.
		160	my @destroy;
		161	my $manager;
		162
		163	$manager = new Coro sub {
		164	while () {
		165	(shift @destroy)->_cancel
		166	while @destroy;
		167
		168	&schedule;
		169	}
		170	};
		171
		172	$manager->prio (PRIO_MAX);
110		173
111	# static methods. not really.	174	# static methods. not really.
112		175
		176	=back
		177
113	=head2 STATIC METHODS	178	=head2 STATIC METHODS
114		179
115	Static methods are actually functions that operate on the current process only.	180	Static methods are actually functions that operate on the current coroutine only.
116		181
117	=over 4	182	=over 4
118		183
119	=item async { ... } [@args...]	184	=item async { ... } [@args...]
120		185
121	Create a new asynchronous process and return it's process object	186	Create a new asynchronous coroutine and return it's coroutine object
122	(usually unused). When the sub returns the new process is automatically	187	(usually unused). When the sub returns the new coroutine is automatically
123	terminated.	188	terminated.
		189
		190	Calling C<exit> in a coroutine will not work correctly, so do not do that.
		191
		192	When the coroutine dies, the program will exit, just as in the main
		193	program.
124		194
125	# create a new coroutine that just prints its arguments	195	# create a new coroutine that just prints its arguments
126	async {	196	async {
127	print "@_\n";	197	print "@_\n";
128	} 1,2,3,4;	198	} 1,2,3,4;
129		199
130	The coderef you submit MUST NOT be a closure that refers to variables
131	in an outer scope. This does NOT work. Pass arguments into it instead.
132
133	=cut	200	=cut
134		201
135	sub async(&@) {	202	sub async(&@) {
136	my $pid = new Coro @_;	203	my $coro = new Coro @_;
137	$pid->ready;	204	$coro->ready;
138	$pid;	205	$coro
139	}	206	}
140		207
141	=item schedule	208	=item schedule
142		209
143	Calls the scheduler. Please note that the current process will not be put	210	Calls the scheduler. Please note that the current coroutine will not be put
144	into the ready queue, so calling this function usually means you will	211	into the ready queue, so calling this function usually means you will
145	never be called again.	212	never be called again unless something else (e.g. an event handler) calls
		213	ready.
146		214
147	=cut	215	The canonical way to wait on external events is this:
148		216
149	my $prev;	217	{
		218	# remember current coroutine
		219	my $current = $Coro::current;
150		220
151	sub schedule {	221	# register a hypothetical event handler
152	# should be done using priorities :(	222	on_event_invoke sub {
153	($prev, $current) = ($current, shift @ready \|\| $idle);	223	# wake up sleeping coroutine
154	Coro::State::transfer($prev, $current);
155	}
156
157	=item yield
158
159	Yield to other processes. This function puts the current process into the
160	ready queue and calls C<schedule>.
161
162	=cut
163
164	sub yield {
165	$current->ready;	224	$current->ready;
166	&schedule;	225	undef $current;
167	}	226	};
168		227
		228	# call schedule until event occured.
		229	# in case we are woken up for other reasons
		230	# (current still defined), loop.
		231	Coro::schedule while $current;
		232	}
		233
		234	=item cede
		235
		236	"Cede" to other coroutines. This function puts the current coroutine into the
		237	ready queue and calls C<schedule>, which has the effect of giving up the
		238	current "timeslice" to other coroutines of the same or higher priority.
		239
		240	=item Coro::cede_notself
		241
		242	Works like cede, but is not exported by default and will cede to any
		243	coroutine, regardless of priority, once.
		244
169	=item terminate	245	=item terminate [arg...]
170		246
171	Terminates the current process.	247	Terminates the current coroutine with the given status values (see L<cancel>).
172
173	Future versions of this function will allow result arguments.
174		248
175	=cut	249	=cut
176		250
177	sub terminate {	251	sub terminate {
178	$current->{_results} = [@_];	252	$current->cancel (@_);
179	&schedule;
180	}	253	}
181		254
182	=back	255	=back
183		256
184	# dynamic methods	257	# dynamic methods
185		258
186	=head2 PROCESS METHODS	259	=head2 COROUTINE METHODS
187		260
188	These are the methods you can call on process objects.	261	These are the methods you can call on coroutine objects.
189		262
190	=over 4	263	=over 4
191		264
192	=item new Coro \&sub [, @args...]	265	=item new Coro \&sub [, @args...]
193		266
194	Create a new process and return it. When the sub returns the process	267	Create a new coroutine and return it. When the sub returns the coroutine
195	automatically terminates. To start the process you must first put it into	268	automatically terminates as if C<terminate> with the returned values were
		269	called. To make the coroutine run you must first put it into the ready queue
196	the ready queue by calling the ready method.	270	by calling the ready method.
197		271
198	The coderef you submit MUST NOT be a closure that refers to variables	272	Calling C<exit> in a coroutine will not work correctly, so do not do that.
199	in an outer scope. This does NOT work. Pass arguments into it instead.
200		273
201	=cut	274	=cut
202		275
203	sub _newcoro {	276	sub _run_coro {
204	terminate &{+shift};	277	terminate &{+shift};
205	}	278	}
206		279
207	sub new {	280	sub new {
208	my $class = shift;	281	my $class = shift;
209	bless {
210	_coro_state => (new Coro::State $_[0] && \&_newcoro, @_),
211	}, $class;
212	}
213		282
214	=item $process->ready	283	$class->SUPER::new (\&_run_coro, @_)
		284	}
215		285
216	Put the current process into the ready queue.	286	=item $success = $coroutine->ready
217		287
218	=cut	288	Put the given coroutine into the ready queue (according to it's priority)
		289	and return true. If the coroutine is already in the ready queue, do nothing
		290	and return false.
219		291
220	sub ready {	292	=item $is_ready = $coroutine->is_ready
221	push @ready, $_[0];	293
		294	Return wether the coroutine is currently the ready queue or not,
		295
		296	=item $coroutine->cancel (arg...)
		297
		298	Terminates the given coroutine and makes it return the given arguments as
		299	status (default: the empty list). Never returns if the coroutine is the
		300	current coroutine.
		301
		302	=cut
		303
		304	sub cancel {
		305	my $self = shift;
		306	$self->{status} = [@_];
		307
		308	if ($current == $self) {
		309	push @destroy, $self;
		310	$manager->ready;
		311	&schedule while 1;
		312	} else {
		313	$self->_cancel;
		314	}
		315	}
		316
		317	=item $coroutine->join
		318
		319	Wait until the coroutine terminates and return any values given to the
		320	C<terminate> or C<cancel> functions. C<join> can be called multiple times
		321	from multiple coroutine.
		322
		323	=cut
		324
		325	sub join {
		326	my $self = shift;
		327
		328	unless ($self->{status}) {
		329	my $current = $current;
		330
		331	push @{$self->{destroy_cb}}, sub {
		332	$current->ready;
		333	undef $current;
		334	};
		335
		336	&schedule while $current;
		337	}
		338
		339	wantarray ? @{$self->{status}} : $self->{status}[0];
		340	}
		341
		342	=item $coroutine->on_destroy (\&cb)
		343
		344	Registers a callback that is called when this coroutine gets destroyed,
		345	but before it is joined. The callback gets passed the terminate arguments,
		346	if any.
		347
		348	=cut
		349
		350	sub on_destroy {
		351	my ($self, $cb) = @_;
		352
		353	push @{ $self->{destroy_cb} }, $cb;
		354	}
		355
		356	=item $oldprio = $coroutine->prio ($newprio)
		357
		358	Sets (or gets, if the argument is missing) the priority of the
		359	coroutine. Higher priority coroutines get run before lower priority
		360	coroutines. Priorities are small signed integers (currently -4 .. +3),
		361	that you can refer to using PRIO_xxx constants (use the import tag :prio
		362	to get then):
		363
		364	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
		365	3 > 1 > 0 > -1 > -3 > -4
		366
		367	# set priority to HIGH
		368	current->prio(PRIO_HIGH);
		369
		370	The idle coroutine ($Coro::idle) always has a lower priority than any
		371	existing coroutine.
		372
		373	Changing the priority of the current coroutine will take effect immediately,
		374	but changing the priority of coroutines in the ready queue (but not
		375	running) will only take effect after the next schedule (of that
		376	coroutine). This is a bug that will be fixed in some future version.
		377
		378	=item $newprio = $coroutine->nice ($change)
		379
		380	Similar to C<prio>, but subtract the given value from the priority (i.e.
		381	higher values mean lower priority, just as in unix).
		382
		383	=item $olddesc = $coroutine->desc ($newdesc)
		384
		385	Sets (or gets in case the argument is missing) the description for this
		386	coroutine. This is just a free-form string you can associate with a coroutine.
		387
		388	=cut
		389
		390	sub desc {
		391	my $old = $_[0]{desc};
		392	$_[0]{desc} = $_[1] if @_ > 1;
		393	$old;
222	}	394	}
223		395
224	=back	396	=back
225		397
		398	=head2 GLOBAL FUNCTIONS
		399
		400	=over 4
		401
		402	=item Coro::nready
		403
		404	Returns the number of coroutines that are currently in the ready state,
		405	i.e. that can be swicthed to. The value C<0> means that the only runnable
		406	coroutine is the currently running one, so C<cede> would have no effect,
		407	and C<schedule> would cause a deadlock unless there is an idle handler
		408	that wakes up some coroutines.
		409
		410	=item my $guard = Coro::guard { ... }
		411
		412	This creates and returns a guard object. Nothing happens until the objetc
		413	gets destroyed, in which case the codeblock given as argument will be
		414	executed. This is useful to free locks or other resources in case of a
		415	runtime error or when the coroutine gets canceled, as in both cases the
		416	guard block will be executed. The guard object supports only one method,
		417	C<< ->cancel >>, which will keep the codeblock from being executed.
		418
		419	Example: set some flag and clear it again when the coroutine gets canceled
		420	or the function returns:
		421
		422	sub do_something {
		423	my $guard = Coro::guard { $busy = 0 };
		424	$busy = 1;
		425
		426	# do something that requires $busy to be true
		427	}
		428
		429	=cut
		430
		431	sub guard(&) {
		432	bless \(my $cb = $_[0]), "Coro::guard"
		433	}
		434
		435	sub Coro::guard::cancel {
		436	${$_[0]} = sub { };
		437	}
		438
		439	sub Coro::guard::DESTROY {
		440	${$_[0]}->();
		441	}
		442
		443
		444	=item unblock_sub { ... }
		445
		446	This utility function takes a BLOCK or code reference and "unblocks" it,
		447	returning the new coderef. This means that the new coderef will return
		448	immediately without blocking, returning nothing, while the original code
		449	ref will be called (with parameters) from within its own coroutine.
		450
		451	The reason this fucntion exists is that many event libraries (such as the
		452	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		453	of thread-safety). This means you must not block within event callbacks,
		454	otherwise you might suffer from crashes or worse.
		455
		456	This function allows your callbacks to block by executing them in another
		457	coroutine where it is safe to block. One example where blocking is handy
		458	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		459	disk.
		460
		461	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		462	creating event callbacks that want to block.
		463
		464	=cut
		465
		466	our @unblock_pool;
		467	our @unblock_queue;
		468	our $UNBLOCK_POOL_SIZE = 2;
		469
		470	sub unblock_handler_ {
		471	while () {
		472	my ($cb, @arg) = @{ delete $Coro::current->{arg} };
		473	$cb->(@arg);
		474
		475	last if @unblock_pool >= $UNBLOCK_POOL_SIZE;
		476	push @unblock_pool, $Coro::current;
		477	schedule;
		478	}
		479	}
		480
		481	our $unblock_scheduler = async {
		482	while () {
		483	while (my $cb = pop @unblock_queue) {
		484	my $handler = (pop @unblock_pool or new Coro \&unblock_handler_);
		485	$handler->{arg} = $cb;
		486	$handler->ready;
		487	cede;
		488	}
		489
		490	schedule;
		491	}
		492	};
		493
		494	sub unblock_sub(&) {
		495	my $cb = shift;
		496
		497	sub {
		498	push @unblock_queue, [$cb, @_];
		499	$unblock_scheduler->ready;
		500	}
		501	}
		502
		503	=back
		504
226	=cut	505	=cut
227		506
228	1;	507	1;
229		508
230	=head1 BUGS/LIMITATIONS	509	=head1 BUGS/LIMITATIONS
231		510
232	- could be faster, especially when the core would introduce special	511	- you must make very sure that no coro is still active on global
233	support for coroutines (like it does for threads).	512	destruction. very bad things might happen otherwise (usually segfaults).
234	- there is still a memleak on coroutine termination that I could not	513
235	identify. Could be as small as a single SV.
236	- this module is not well-tested.
237	- if variables or arguments "disappear" (become undef) or become
238	corrupted please contact the author so he cen iron out the
239	remaining bugs.
240	- this module is not thread-safe. You must only ever use this module from	514	- this module is not thread-safe. You should only ever use this module
241	the same thread (this requirement might be loosened in the future to	515	from the same thread (this requirement might be losened in the future
242	allow per-thread schedulers, but Coro::State does not yet allow this).	516	to allow per-thread schedulers, but Coro::State does not yet allow
		517	this).
243		518
244	=head1 SEE ALSO	519	=head1 SEE ALSO
245		520
246	L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,	521	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.
247	L<Coro::Signal>, L<Coro::State>, L<Coro::Event>.	522
		523	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
		524
		525	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.
		526
		527	Embedding: L<Coro:MakeMaker>
248		528
249	=head1 AUTHOR	529	=head1 AUTHOR
250		530
251	Marc Lehmann <pcg@goof.com>	531	Marc Lehmann <schmorp@schmorp.de>
252	http://www.goof.com/pcg/marc/	532	http://home.schmorp.de/
253		533
254	=cut	534	=cut
255		535

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Comparing Coro/Coro.pm (file contents): Revision 1.20 by root, Sat Jul 21 18:21:45 2001 UTC vs. Revision 1.104 by root, Thu Jan 4 23:49:27 2007 UTC

Diff Legend

Comparing Coro/Coro.pm (file contents):
Revision 1.20 by root, Sat Jul 21 18:21:45 2001 UTC vs.
Revision 1.104 by root, Thu Jan 4 23:49:27 2007 UTC