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

Comparing Coro/Coro.pm (file contents):
Revision 1.22 by root, Mon Jul 23 02:14:19 2001 UTC vs.
Revision 1.102 by root, Fri Dec 29 11:37:49 2006 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 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	WARNING: When using this module, make sure that, at program end, no
34	coroutines are still running OR just call exit before falling off the
35	end. The reason for this is that some coroutine of yours might have called
36	into a C function, and falling off the end of main:: results in returning
37	to that C function instead if to the main C interpreter.
38
39	WARNING: Unless you really know what you are doing, do NOT do context
40	switches inside callbacks from the XS level. The reason for this is
41	similar to the reason above: A callback calls a perl function, this
42	perl function does a context switch, some other callback is called, the
43	original function returns from it - to what? To the wrong XS function,
44	with totally different return values. Unfortunately, this includes
45	callbacks done by perl itself (tie'd variables!).
46
47	The only workaround for this is to do coroutines on C level.
48
49	=cut	40	=cut
50		41
51	package Coro;	42	package Coro;
52		43
		44	use strict;
		45	no warnings "uninitialized";
		46
53	use Coro::State;	47	use Coro::State;
54		48
55	use base Exporter;	49	use base qw(Coro::State Exporter);
56		50
57	$VERSION = 0.10;	51	our $idle; # idle handler
		52	our $main; # main coroutine
		53	our $current; # current coroutine
58		54
		55	our $VERSION = '3.3';
		56
59	@EXPORT = qw(async cede schedule terminate current);	57	our @EXPORT = qw(async cede schedule terminate current unblock_sub);
60	@EXPORT_OK = qw($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));
61		62
62	{	63	{
63	my @async;	64	my @async;
		65	my $init;
64		66
65	# this way of handling attributes simply is NOT scalable ;()	67	# this way of handling attributes simply is NOT scalable ;()
66	sub import {	68	sub import {
		69	no strict 'refs';
		70
67	Coro->export_to_level(1, @_);	71	Coro->export_to_level (1, @_);
		72
68	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};	73	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
69	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {	74	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
70	my ($package, $ref) = (shift, shift);	75	my ($package, $ref) = (shift, shift);
71	my @attrs;	76	my @attrs;
72	for (@_) {	77	for (@_) {
73	if ($_ eq "Coro") {	78	if ($_ eq "Coro") {
74	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	}
75	} else {	87	} else {
76	push @attrs, $_;	88	push @attrs, $_;
77	}	89	}
78	}	90	}
79	return $old ? $old->($package, $ref, @attrs) : @attrs;	91	return $old ? $old->($package, $ref, @attrs) : @attrs;
80	};	92	};
81	}	93	}
82		94
83	sub INIT {
84	&async(pop @async) while @async;
85	}
86	}	95	}
		96
		97	=over 4
87		98
88	=item $main	99	=item $main
89		100
90	This coroutine represents the main program.	101	This coroutine represents the main program.
91		102
92	=cut	103	=cut
93		104
94	our $main = new Coro;	105	$main = new Coro;
95		106
96	=item $current (or as function: current)	107	=item $current (or as function: current)
97		108
98	The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).	109	The current coroutine (the last coroutine switched to). The initial value
		110	is C<$main> (of course).
		111
		112	This variable is B<strictly> I<read-only>. It is provided for performance
		113	reasons. If performance is not essentiel you are encouraged to use the
		114	C<Coro::current> function instead.
99		115
100	=cut	116	=cut
101		117
102	# maybe some other module used Coro::Specific before...	118	# maybe some other module used Coro::Specific before...
103	if ($current) {
104	$main->{specific} = $current->{specific};	119	$main->{specific} = $current->{specific}
105	}	120	if $current;
106		121
107	our $current = $main;	122	_set_current $main;
108		123
109	sub current() { $current }	124	sub current() { $current }
110		125
111	=item $idle	126	=item $idle
112		127
113	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
114	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.
115		131
116	=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.
117		135
118	# should be done using priorities :(	136	Please note that if your callback recursively invokes perl (e.g. for event
119	our $idle = new Coro sub {	137	handlers), then it must be prepared to be called recursively.
120	print STDERR "FATAL: deadlock detected\n";	138
121	exit(51);	139	=cut
		140
		141	$idle = sub {
		142	require Carp;
		143	Carp::croak ("FATAL: deadlock detected");
122	};	144	};
123		145
124	# we really need priorities...	146	# this coroutine is necessary because a coroutine
125	my @ready; # the ready queue. hehe, rather broken ;)	147	# cannot destroy itself.
		148	my @destroy;
		149	my $manager; $manager = new Coro sub {
		150	while () {
		151	# by overwriting the state object with the manager we destroy it
		152	# while still being able to schedule this coroutine (in case it has
		153	# been readied multiple times. this is harmless since the manager
		154	# can be called as many times as neccessary and will always
		155	# remove itself from the runqueue
		156	while (@destroy) {
		157	my $coro = pop @destroy;
		158
		159	$coro->{status} \|\|= [];
		160
		161	$_->ready for @{(delete $coro->{join} ) \|\| []};
		162	$_->(@{$coro->{status}}) for @{(delete $coro->{destroy_cb}) \|\| []};
		163
		164	# the next line destroys the coro state, but keeps the
		165	# coroutine itself intact (we basically make it a zombie
		166	# coroutine that always runs the manager thread, so it's possible
		167	# to transfer() to this coroutine).
		168	$coro->_clone_state_from ($manager);
		169	}
		170	&schedule;
		171	}
		172	};
126		173
127	# static methods. not really.	174	# static methods. not really.
128		175
		176	=back
		177
129	=head2 STATIC METHODS	178	=head2 STATIC METHODS
130		179
131	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.
132		181
133	=over 4	182	=over 4
134		183
135	=item async { ... } [@args...]	184	=item async { ... } [@args...]
136		185
137	Create a new asynchronous process and return it's process object	186	Create a new asynchronous coroutine and return it's coroutine object
138	(usually unused). When the sub returns the new process is automatically	187	(usually unused). When the sub returns the new coroutine is automatically
139	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.
140		194
141	# create a new coroutine that just prints its arguments	195	# create a new coroutine that just prints its arguments
142	async {	196	async {
143	print "@_\n";	197	print "@_\n";
144	} 1,2,3,4;	198	} 1,2,3,4;
145		199
146	The coderef you submit MUST NOT be a closure that refers to variables
147	in an outer scope. This does NOT work. Pass arguments into it instead.
148
149	=cut	200	=cut
150		201
151	sub async(&@) {	202	sub async(&@) {
152	my $pid = new Coro @_;	203	my $pid = new Coro @_;
153	$pid->ready;	204	$pid->ready;
154	$pid;	205	$pid
155	}	206	}
156		207
157	=item schedule	208	=item schedule
158		209
159	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
160	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
161	never be called again.	212	never be called again unless something else (e.g. an event handler) calls
		213	ready.
162		214
163	=cut	215	The canonical way to wait on external events is this:
164		216
165	my $prev;	217	{
		218	# remember current coroutine
		219	my $current = $Coro::current;
166		220
167	sub schedule {	221	# register a hypothetical event handler
168	# should be done using priorities :(	222	on_event_invoke sub {
169	($prev, $current) = ($current, shift @ready \|\| $idle);	223	# wake up sleeping coroutine
170	Coro::State::transfer($prev, $current);	224	$current->ready;
171	}	225	undef $current;
		226	};
		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	}
172		233
173	=item cede	234	=item cede
174		235
175	"Cede" to other processes. This function puts the current process into the	236	"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	237	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.	238	current "timeslice" to other coroutines of the same or higher priority.
178		239
179	=cut	240	=item Coro::cede_notself
180		241
181	sub cede {	242	Works like cede, but is not exported by default and will cede to any
182	$current->ready;	243	coroutine, regardless of priority, once.
183	&schedule;
184	}
185		244
186	=item terminate	245	=item terminate [arg...]
187		246
188	Terminates the current process.	247	Terminates the current coroutine with the given status values (see L<cancel>).
189
190	Future versions of this function will allow result arguments.
191		248
192	=cut	249	=cut
193		250
194	sub terminate {	251	sub terminate {
195	my $self = $current;	252	$current->cancel (@_);
196	$self->{_results} = [@_];
197	$current = shift @ready \|\| $idle;
198	Coro::State::transfer(delete $self->{_coro_state}, $current);
199	# cannot return
200	die;
201	}	253	}
202		254
203	=back	255	=back
204		256
205	# dynamic methods	257	# dynamic methods
206		258
207	=head2 PROCESS METHODS	259	=head2 COROUTINE METHODS
208		260
209	These are the methods you can call on process objects.	261	These are the methods you can call on coroutine objects.
210		262
211	=over 4	263	=over 4
212		264
213	=item new Coro \&sub [, @args...]	265	=item new Coro \&sub [, @args...]
214		266
215	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
216	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
217	the ready queue by calling the ready method.	270	by calling the ready method.
218		271
219	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.
220	in an outer scope. This does NOT work. Pass arguments into it instead.
221		273
222	=cut	274	=cut
223		275
224	sub _newcoro {	276	sub _run_coro {
225	terminate &{+shift};	277	terminate &{+shift};
226	}	278	}
227		279
228	sub new {	280	sub new {
229	my $class = shift;	281	my $class = shift;
230	bless {
231	_coro_state => (new Coro::State $_[0] && \&_newcoro, @_),
232	}, $class;
233	}
234		282
235	=item $process->ready	283	$class->SUPER::new (\&_run_coro, @_)
		284	}
236		285
237	Put the current process into the ready queue.	286	=item $success = $coroutine->ready
238		287
239	=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.
240		291
241	sub ready {	292	=item $is_ready = $coroutine->is_ready
242	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).
		300
		301	=cut
		302
		303	sub cancel {
		304	my $self = shift;
		305	$self->{status} = [@_];
		306	push @destroy, $self;
		307	$manager->ready;
		308	&schedule if $current == $self;
		309	}
		310
		311	=item $coroutine->join
		312
		313	Wait until the coroutine terminates and return any values given to the
		314	C<terminate> or C<cancel> functions. C<join> can be called multiple times
		315	from multiple coroutine.
		316
		317	=cut
		318
		319	sub join {
		320	my $self = shift;
		321	unless ($self->{status}) {
		322	push @{$self->{join}}, $current;
		323	&schedule;
		324	}
		325	wantarray ? @{$self->{status}} : $self->{status}[0];
		326	}
		327
		328	=item $coroutine->on_destroy (\&cb)
		329
		330	Registers a callback that is called when this coroutine gets destroyed,
		331	but before it is joined. The callback gets passed the terminate arguments,
		332	if any.
		333
		334	=cut
		335
		336	sub on_destroy {
		337	my ($self, $cb) = @_;
		338
		339	push @{ $self->{destroy_cb} }, $cb;
		340	}
		341
		342	=item $oldprio = $coroutine->prio ($newprio)
		343
		344	Sets (or gets, if the argument is missing) the priority of the
		345	coroutine. Higher priority coroutines get run before lower priority
		346	coroutines. Priorities are small signed integers (currently -4 .. +3),
		347	that you can refer to using PRIO_xxx constants (use the import tag :prio
		348	to get then):
		349
		350	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
		351	3 > 1 > 0 > -1 > -3 > -4
		352
		353	# set priority to HIGH
		354	current->prio(PRIO_HIGH);
		355
		356	The idle coroutine ($Coro::idle) always has a lower priority than any
		357	existing coroutine.
		358
		359	Changing the priority of the current coroutine will take effect immediately,
		360	but changing the priority of coroutines in the ready queue (but not
		361	running) will only take effect after the next schedule (of that
		362	coroutine). This is a bug that will be fixed in some future version.
		363
		364	=item $newprio = $coroutine->nice ($change)
		365
		366	Similar to C<prio>, but subtract the given value from the priority (i.e.
		367	higher values mean lower priority, just as in unix).
		368
		369	=item $olddesc = $coroutine->desc ($newdesc)
		370
		371	Sets (or gets in case the argument is missing) the description for this
		372	coroutine. This is just a free-form string you can associate with a coroutine.
		373
		374	=cut
		375
		376	sub desc {
		377	my $old = $_[0]{desc};
		378	$_[0]{desc} = $_[1] if @_ > 1;
		379	$old;
243	}	380	}
244		381
245	=back	382	=back
246		383
		384	=head2 GLOBAL FUNCTIONS
		385
		386	=over 4
		387
		388	=item Coro::nready
		389
		390	Returns the number of coroutines that are currently in the ready state,
		391	i.e. that can be swicthed to. The value C<0> means that the only runnable
		392	coroutine is the currently running one, so C<cede> would have no effect,
		393	and C<schedule> would cause a deadlock unless there is an idle handler
		394	that wakes up some coroutines.
		395
		396	=item unblock_sub { ... }
		397
		398	This utility function takes a BLOCK or code reference and "unblocks" it,
		399	returning the new coderef. This means that the new coderef will return
		400	immediately without blocking, returning nothing, while the original code
		401	ref will be called (with parameters) from within its own coroutine.
		402
		403	The reason this fucntion exists is that many event libraries (such as the
		404	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		405	of thread-safety). This means you must not block within event callbacks,
		406	otherwise you might suffer from crashes or worse.
		407
		408	This function allows your callbacks to block by executing them in another
		409	coroutine where it is safe to block. One example where blocking is handy
		410	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		411	disk.
		412
		413	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		414	creating event callbacks that want to block.
		415
		416	=cut
		417
		418	our @unblock_pool;
		419	our @unblock_queue;
		420	our $UNBLOCK_POOL_SIZE = 2;
		421
		422	sub unblock_handler_ {
		423	while () {
		424	my ($cb, @arg) = @{ delete $Coro::current->{arg} };
		425	$cb->(@arg);
		426
		427	last if @unblock_pool >= $UNBLOCK_POOL_SIZE;
		428	push @unblock_pool, $Coro::current;
		429	schedule;
		430	}
		431	}
		432
		433	our $unblock_scheduler = async {
		434	while () {
		435	while (my $cb = pop @unblock_queue) {
		436	my $handler = (pop @unblock_pool or new Coro \&unblock_handler_);
		437	$handler->{arg} = $cb;
		438	$handler->ready;
		439	cede;
		440	}
		441
		442	schedule;
		443	}
		444	};
		445
		446	sub unblock_sub(&) {
		447	my $cb = shift;
		448
		449	sub {
		450	push @unblock_queue, [$cb, @_];
		451	$unblock_scheduler->ready;
		452	}
		453	}
		454
		455	=back
		456
247	=cut	457	=cut
248		458
249	1;	459	1;
250		460
251	=head1 BUGS/LIMITATIONS	461	=head1 BUGS/LIMITATIONS
252		462
253	- could be faster, especially when the core would introduce special	463	- you must make very sure that no coro is still active on global
254	support for coroutines (like it does for threads).	464	destruction. very bad things might happen otherwise (usually segfaults).
255	- there is still a memleak on coroutine termination that I could not	465
256	identify. Could be as small as a single SV.
257	- this module is not well-tested.
258	- if variables or arguments "disappear" (become undef) or become
259	corrupted please contact the author so he cen iron out the
260	remaining bugs.
261	- this module is not thread-safe. You must only ever use this module from	466	- this module is not thread-safe. You should only ever use this module
262	the same thread (this requirement might be loosened in the future to	467	from the same thread (this requirement might be losened in the future
263	allow per-thread schedulers, but Coro::State does not yet allow this).	468	to allow per-thread schedulers, but Coro::State does not yet allow
		469	this).
264		470
265	=head1 SEE ALSO	471	=head1 SEE ALSO
266		472
267	L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,	473	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.
268	L<Coro::Signal>, L<Coro::State>, L<Coro::Event>.	474
		475	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
		476
		477	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.
		478
		479	Embedding: L<Coro:MakeMaker>
269		480
270	=head1 AUTHOR	481	=head1 AUTHOR
271		482
272	Marc Lehmann <pcg@goof.com>	483	Marc Lehmann <schmorp@schmorp.de>
273	http://www.goof.com/pcg/marc/	484	http://home.schmorp.de/
274		485
275	=cut	486	=cut
276		487

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Comparing Coro/Coro.pm (file contents): Revision 1.22 by root, Mon Jul 23 02:14:19 2001 UTC vs. Revision 1.102 by root, Fri Dec 29 11:37:49 2006 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.22 by root, Mon Jul 23 02:14:19 2001 UTC vs.
Revision 1.102 by root, Fri Dec 29 11:37:49 2006 UTC