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

Comparing cvsroot/Coro/Coro.pm (file contents):
Revision 1.22 by root, Mon Jul 23 02:14:19 2001 UTC vs.
Revision 1.101 by root, Fri Dec 29 08:36:34 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
180
181	sub cede {
182	$current->ready;
183	&schedule;
184	}
185
186	=item terminate	240	=item terminate [arg...]
187		241
188	Terminates the current process.	242	Terminates the current coroutine with the given status values (see L<cancel>).
189
190	Future versions of this function will allow result arguments.
191		243
192	=cut	244	=cut
193		245
194	sub terminate {	246	sub terminate {
195	my $self = $current;	247	$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	}	248	}
202		249
203	=back	250	=back
204		251
205	# dynamic methods	252	# dynamic methods
206		253
207	=head2 PROCESS METHODS	254	=head2 COROUTINE METHODS
208		255
209	These are the methods you can call on process objects.	256	These are the methods you can call on coroutine objects.
210		257
211	=over 4	258	=over 4
212		259
213	=item new Coro \&sub [, @args...]	260	=item new Coro \&sub [, @args...]
214		261
215	Create a new process and return it. When the sub returns the process	262	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	263	automatically terminates as if C<terminate> with the returned values were
		264	called. To make the coroutine run you must first put it into the ready queue
217	the ready queue by calling the ready method.	265	by calling the ready method.
218		266
219	The coderef you submit MUST NOT be a closure that refers to variables	267	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		268
222	=cut	269	=cut
223		270
224	sub _newcoro {	271	sub _run_coro {
225	terminate &{+shift};	272	terminate &{+shift};
226	}	273	}
227		274
228	sub new {	275	sub new {
229	my $class = shift;	276	my $class = shift;
230	bless {
231	_coro_state => (new Coro::State $_[0] && \&_newcoro, @_),
232	}, $class;
233	}
234		277
235	=item $process->ready	278	$class->SUPER::new (\&_run_coro, @_)
		279	}
236		280
237	Put the current process into the ready queue.	281	=item $success = $coroutine->ready
238		282
239	=cut	283	Put the given coroutine into the ready queue (according to it's priority)
		284	and return true. If the coroutine is already in the ready queue, do nothing
		285	and return false.
240		286
241	sub ready {	287	=item $is_ready = $coroutine->is_ready
242	push @ready, $_[0];	288
		289	Return wether the coroutine is currently the ready queue or not,
		290
		291	=item $coroutine->cancel (arg...)
		292
		293	Terminates the given coroutine and makes it return the given arguments as
		294	status (default: the empty list).
		295
		296	=cut
		297
		298	sub cancel {
		299	my $self = shift;
		300	$self->{status} = [@_];
		301	push @destroy, $self;
		302	$manager->ready;
		303	&schedule if $current == $self;
		304	}
		305
		306	=item $coroutine->join
		307
		308	Wait until the coroutine terminates and return any values given to the
		309	C<terminate> or C<cancel> functions. C<join> can be called multiple times
		310	from multiple coroutine.
		311
		312	=cut
		313
		314	sub join {
		315	my $self = shift;
		316	unless ($self->{status}) {
		317	push @{$self->{join}}, $current;
		318	&schedule;
		319	}
		320	wantarray ? @{$self->{status}} : $self->{status}[0];
		321	}
		322
		323	=item $coroutine->on_destroy (\&cb)
		324
		325	Registers a callback that is called when this coroutine gets destroyed,
		326	but before it is joined. The callback gets passed the terminate arguments,
		327	if any.
		328
		329	=cut
		330
		331	sub on_destroy {
		332	my ($self, $cb) = @_;
		333
		334	push @{ $self->{destroy_cb} }, $cb;
		335	}
		336
		337	=item $oldprio = $coroutine->prio ($newprio)
		338
		339	Sets (or gets, if the argument is missing) the priority of the
		340	coroutine. Higher priority coroutines get run before lower priority
		341	coroutines. Priorities are small signed integers (currently -4 .. +3),
		342	that you can refer to using PRIO_xxx constants (use the import tag :prio
		343	to get then):
		344
		345	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
		346	3 > 1 > 0 > -1 > -3 > -4
		347
		348	# set priority to HIGH
		349	current->prio(PRIO_HIGH);
		350
		351	The idle coroutine ($Coro::idle) always has a lower priority than any
		352	existing coroutine.
		353
		354	Changing the priority of the current coroutine will take effect immediately,
		355	but changing the priority of coroutines in the ready queue (but not
		356	running) will only take effect after the next schedule (of that
		357	coroutine). This is a bug that will be fixed in some future version.
		358
		359	=item $newprio = $coroutine->nice ($change)
		360
		361	Similar to C<prio>, but subtract the given value from the priority (i.e.
		362	higher values mean lower priority, just as in unix).
		363
		364	=item $olddesc = $coroutine->desc ($newdesc)
		365
		366	Sets (or gets in case the argument is missing) the description for this
		367	coroutine. This is just a free-form string you can associate with a coroutine.
		368
		369	=cut
		370
		371	sub desc {
		372	my $old = $_[0]{desc};
		373	$_[0]{desc} = $_[1] if @_ > 1;
		374	$old;
243	}	375	}
244		376
245	=back	377	=back
246		378
		379	=head2 GLOBAL FUNCTIONS
		380
		381	=over 4
		382
		383	=item Coro::nready
		384
		385	Returns the number of coroutines that are currently in the ready state,
		386	i.e. that can be swicthed to. The value C<0> means that the only runnable
		387	coroutine is the currently running one, so C<cede> would have no effect,
		388	and C<schedule> would cause a deadlock unless there is an idle handler
		389	that wakes up some coroutines.
		390
		391	=item unblock_sub { ... }
		392
		393	This utility function takes a BLOCK or code reference and "unblocks" it,
		394	returning the new coderef. This means that the new coderef will return
		395	immediately without blocking, returning nothing, while the original code
		396	ref will be called (with parameters) from within its own coroutine.
		397
		398	The reason this fucntion exists is that many event libraries (such as the
		399	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		400	of thread-safety). This means you must not block within event callbacks,
		401	otherwise you might suffer from crashes or worse.
		402
		403	This function allows your callbacks to block by executing them in another
		404	coroutine where it is safe to block. One example where blocking is handy
		405	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		406	disk.
		407
		408	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		409	creating event callbacks that want to block.
		410
		411	=cut
		412
		413	our @unblock_pool;
		414	our @unblock_queue;
		415	our $UNBLOCK_POOL_SIZE = 2;
		416
		417	sub unblock_handler_ {
		418	while () {
		419	my ($cb, @arg) = @{ delete $Coro::current->{arg} };
		420	$cb->(@arg);
		421
		422	last if @unblock_pool >= $UNBLOCK_POOL_SIZE;
		423	push @unblock_pool, $Coro::current;
		424	schedule;
		425	}
		426	}
		427
		428	our $unblock_scheduler = async {
		429	while () {
		430	while (my $cb = pop @unblock_queue) {
		431	my $handler = (pop @unblock_pool or new Coro \&unblock_handler_);
		432	$handler->{arg} = $cb;
		433	$handler->ready;
		434	cede;
		435	}
		436
		437	schedule;
		438	}
		439	};
		440
		441	sub unblock_sub(&) {
		442	my $cb = shift;
		443
		444	sub {
		445	push @unblock_queue, [$cb, @_];
		446	$unblock_scheduler->ready;
		447	}
		448	}
		449
		450	=back
		451
247	=cut	452	=cut
248		453
249	1;	454	1;
250		455
251	=head1 BUGS/LIMITATIONS	456	=head1 BUGS/LIMITATIONS
252		457
253	- could be faster, especially when the core would introduce special	458	- you must make very sure that no coro is still active on global
254	support for coroutines (like it does for threads).	459	destruction. very bad things might happen otherwise (usually segfaults).
255	- there is still a memleak on coroutine termination that I could not	460
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	461	- 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	462	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).	463	to allow per-thread schedulers, but Coro::State does not yet allow
		464	this).
264		465
265	=head1 SEE ALSO	466	=head1 SEE ALSO
266		467
267	L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,	468	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.
268	L<Coro::Signal>, L<Coro::State>, L<Coro::Event>.	469
		470	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
		471
		472	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.
		473
		474	Embedding: L<Coro:MakeMaker>
269		475
270	=head1 AUTHOR	476	=head1 AUTHOR
271		477
272	Marc Lehmann <pcg@goof.com>	478	Marc Lehmann <schmorp@schmorp.de>
273	http://www.goof.com/pcg/marc/	479	http://home.schmorp.de/
274		480
275	=cut	481	=cut
276		482

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Comparing cvsroot/Coro/Coro.pm (file contents): Revision 1.22 by root, Mon Jul 23 02:14:19 2001 UTC vs. Revision 1.101 by root, Fri Dec 29 08:36:34 2006 UTC

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Comparing cvsroot/Coro/Coro.pm (file contents):
Revision 1.22 by root, Mon Jul 23 02:14:19 2001 UTC vs.
Revision 1.101 by root, Fri Dec 29 08:36:34 2006 UTC