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

Comparing Coro/Coro.pm (file contents):
Revision 1.21 by root, Sun Jul 22 03:24:10 2001 UTC vs.
Revision 1.137 by root, Wed Sep 26 19:26:48 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 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), 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	=cut	40	=cut
40		41
41	package Coro;	42	package Coro;
42		43
		44	use strict;
		45	no warnings "uninitialized";
		46
43	use Coro::State;	47	use Coro::State;
44		48
45	use base Exporter;	49	use base qw(Coro::State Exporter);
46		50
47	$VERSION = 0.10;	51	our $idle; # idle handler
		52	our $main; # main coroutine
		53	our $current; # current coroutine
48		54
		55	our $VERSION = '3.7';
		56
49	@EXPORT = qw(async yield schedule terminate current);	57	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
50	@EXPORT_OK = qw($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));
51		62
52	{	63	{
53	my @async;	64	my @async;
		65	my $init;
54		66
55	# this way of handling attributes simply is NOT scalable ;()	67	# this way of handling attributes simply is NOT scalable ;()
56	sub import {	68	sub import {
		69	no strict 'refs';
		70
57	Coro->export_to_level(1, @_);	71	Coro->export_to_level (1, @_);
		72
58	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};	73	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
59	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {	74	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
60	my ($package, $ref) = (shift, shift);	75	my ($package, $ref) = (shift, shift);
61	my @attrs;	76	my @attrs;
62	for (@_) {	77	for (@_) {
63	if ($_ eq "Coro") {	78	if ($_ eq "Coro") {
64	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	}
65	} else {	87	} else {
66	push @attrs, $_;	88	push @attrs, $_;
67	}	89	}
68	}	90	}
69	return $old ? $old->($package, $ref, @attrs) : @attrs;	91	return $old ? $old->($package, $ref, @attrs) : @attrs;
70	};	92	};
71	}	93	}
72		94
73	sub INIT {
74	&async(pop @async) while @async;
75	}
76	}	95	}
		96
		97	=over 4
77		98
78	=item $main	99	=item $main
79		100
80	This coroutine represents the main program.	101	This coroutine represents the main program.
81		102
82	=cut	103	=cut
83		104
84	our $main = new Coro;	105	$main = new Coro;
85		106
86	=item $current (or as function: current)	107	=item $current (or as function: current)
87		108
88	The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).	109	The current coroutine (the last coroutine switched to). The initial value
		110	is C<$main> (of course).
89		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.
		115
90	=cut	116	=cut
		117
		118	$main->{desc} = "[main::]";
91		119
92	# maybe some other module used Coro::Specific before...	120	# maybe some other module used Coro::Specific before...
93	if ($current) {
94	$main->{specific} = $current->{specific};	121	$main->{specific} = $current->{specific}
95	}	122	if $current;
96		123
97	our $current = $main;	124	_set_current $main;
98		125
99	sub current() { $current }	126	sub current() { $current }
100		127
101	=item $idle	128	=item $idle
102		129
103	The coroutine to switch to when no other coroutine is running. The default	130	A callback that is called whenever the scheduler finds no ready coroutines
104	implementation prints "FATAL: deadlock detected" and exits.	131	to run. The default implementation prints "FATAL: deadlock detected" and
		132	exits, because the program has no other way to continue.
105		133
106	=cut	134	This hook is overwritten by modules such as C<Coro::Timer> and
		135	C<Coro::Event> to wait on an external event that hopefully wake up a
		136	coroutine so the scheduler can run it.
107		137
108	# should be done using priorities :(	138	Please note that if your callback recursively invokes perl (e.g. for event
109	our $idle = new Coro sub {	139	handlers), then it must be prepared to be called recursively.
110	print STDERR "FATAL: deadlock detected\n";	140
111	exit(51);	141	=cut
		142
		143	$idle = sub {
		144	require Carp;
		145	Carp::croak ("FATAL: deadlock detected");
112	};	146	};
113		147
114	# we really need priorities...	148	sub _cancel {
115	my @ready; # the ready queue. hehe, rather broken ;)	149	my ($self) = @_;
		150
		151	# free coroutine data and mark as destructed
		152	$self->_destroy
		153	or return;
		154
		155	# call all destruction callbacks
		156	$_->(@{$self->{status}})
		157	for @{(delete $self->{destroy_cb}) \|\| []};
		158	}
		159
		160	sub _do_trace {
		161	$current->{_trace_cb}->();
		162	}
		163
		164	# this coroutine is necessary because a coroutine
		165	# cannot destroy itself.
		166	my @destroy;
		167	my $manager;
		168
		169	$manager = new Coro sub {
		170	while () {
		171	(shift @destroy)->_cancel
		172	while @destroy;
		173
		174	&schedule;
		175	}
		176	};
		177	$manager->desc ("[coro manager]");
		178	$manager->prio (PRIO_MAX);
116		179
117	# static methods. not really.	180	# static methods. not really.
118		181
		182	=back
		183
119	=head2 STATIC METHODS	184	=head2 STATIC METHODS
120		185
121	Static methods are actually functions that operate on the current process only.	186	Static methods are actually functions that operate on the current coroutine only.
122		187
123	=over 4	188	=over 4
124		189
125	=item async { ... } [@args...]	190	=item async { ... } [@args...]
126		191
127	Create a new asynchronous process and return it's process object	192	Create a new asynchronous coroutine and return it's coroutine object
128	(usually unused). When the sub returns the new process is automatically	193	(usually unused). When the sub returns the new coroutine is automatically
129	terminated.	194	terminated.
		195
		196	Calling C<exit> in a coroutine will do the same as calling exit outside
		197	the coroutine. Likewise, when the coroutine dies, the program will exit,
		198	just as it would in the main program.
130		199
131	# create a new coroutine that just prints its arguments	200	# create a new coroutine that just prints its arguments
132	async {	201	async {
133	print "@_\n";	202	print "@_\n";
134	} 1,2,3,4;	203	} 1,2,3,4;
135		204
136	The coderef you submit MUST NOT be a closure that refers to variables
137	in an outer scope. This does NOT work. Pass arguments into it instead.
138
139	=cut	205	=cut
140		206
141	sub async(&@) {	207	sub async(&@) {
142	my $pid = new Coro @_;	208	my $coro = new Coro @_;
143	$pid->ready;	209	$coro->ready;
144	$pid;	210	$coro
		211	}
		212
		213	=item async_pool { ... } [@args...]
		214
		215	Similar to C<async>, but uses a coroutine pool, so you should not call
		216	terminate or join (although you are allowed to), and you get a coroutine
		217	that might have executed other code already (which can be good or bad :).
		218
		219	Also, the block is executed in an C<eval> context and a warning will be
		220	issued in case of an exception instead of terminating the program, as
		221	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
		222	will not work in the expected way, unless you call terminate or cancel,
		223	which somehow defeats the purpose of pooling.
		224
		225	The priority will be reset to C<0> after each job, otherwise the coroutine
		226	will be re-used "as-is".
		227
		228	The pool size is limited to 8 idle coroutines (this can be adjusted by
		229	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
		230	required.
		231
		232	If you are concerned about pooled coroutines growing a lot because a
		233	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
		234	{ terminate }> once per second or so to slowly replenish the pool. In
		235	addition to that, when the stacks used by a handler grows larger than 16kb
		236	(adjustable with $Coro::POOL_RSS) it will also exit.
		237
		238	=cut
		239
		240	our $POOL_SIZE = 8;
		241	our $POOL_RSS = 16 * 1024;
		242	our @async_pool;
		243
		244	sub pool_handler {
		245	my $cb;
		246
		247	while () {
		248	eval {
		249	while () {
		250	_pool_1 $cb;
		251	&$cb;
		252	_pool_2 $cb;
		253	&schedule;
		254	}
		255	};
		256
		257	last if $@ eq "\3terminate\2\n";
		258	warn $@ if $@;
		259	}
		260	}
		261
		262	sub async_pool(&@) {
		263	# this is also inlined into the unlock_scheduler
		264	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		265
		266	$coro->{_invoke} = [@_];
		267	$coro->ready;
		268
		269	$coro
145	}	270	}
146		271
147	=item schedule	272	=item schedule
148		273
149	Calls the scheduler. Please note that the current process will not be put	274	Calls the scheduler. Please note that the current coroutine will not be put
150	into the ready queue, so calling this function usually means you will	275	into the ready queue, so calling this function usually means you will
151	never be called again.	276	never be called again unless something else (e.g. an event handler) calls
		277	ready.
152		278
153	=cut	279	The canonical way to wait on external events is this:
154		280
155	my $prev;	281	{
		282	# remember current coroutine
		283	my $current = $Coro::current;
156		284
157	sub schedule {	285	# register a hypothetical event handler
158	# should be done using priorities :(	286	on_event_invoke sub {
159	($prev, $current) = ($current, shift @ready \|\| $idle);	287	# wake up sleeping coroutine
160	Coro::State::transfer($prev, $current);
161	}
162
163	=item yield
164
165	Yield to other processes. This function puts the current process into the
166	ready queue and calls C<schedule>.
167
168	=cut
169
170	sub yield {
171	$current->ready;	288	$current->ready;
172	&schedule;	289	undef $current;
173	}	290	};
174		291
		292	# call schedule until event occurred.
		293	# in case we are woken up for other reasons
		294	# (current still defined), loop.
		295	Coro::schedule while $current;
		296	}
		297
		298	=item cede
		299
		300	"Cede" to other coroutines. This function puts the current coroutine into the
		301	ready queue and calls C<schedule>, which has the effect of giving up the
		302	current "timeslice" to other coroutines of the same or higher priority.
		303
		304	Returns true if at least one coroutine switch has happened.
		305
		306	=item Coro::cede_notself
		307
		308	Works like cede, but is not exported by default and will cede to any
		309	coroutine, regardless of priority, once.
		310
		311	Returns true if at least one coroutine switch has happened.
		312
175	=item terminate	313	=item terminate [arg...]
176		314
177	Terminates the current process.	315	Terminates the current coroutine with the given status values (see L<cancel>).
178
179	Future versions of this function will allow result arguments.
180		316
181	=cut	317	=cut
182		318
183	sub terminate {	319	sub terminate {
184	$current->{_results} = [@_];	320	$current->cancel (@_);
185	delete $current->{_coro_state};
186	&schedule;
187	}	321	}
188		322
189	=back	323	=back
190		324
191	# dynamic methods	325	# dynamic methods
192		326
193	=head2 PROCESS METHODS	327	=head2 COROUTINE METHODS
194		328
195	These are the methods you can call on process objects.	329	These are the methods you can call on coroutine objects.
196		330
197	=over 4	331	=over 4
198		332
199	=item new Coro \&sub [, @args...]	333	=item new Coro \&sub [, @args...]
200		334
201	Create a new process and return it. When the sub returns the process	335	Create a new coroutine and return it. When the sub returns the coroutine
202	automatically terminates. To start the process you must first put it into	336	automatically terminates as if C<terminate> with the returned values were
		337	called. To make the coroutine run you must first put it into the ready queue
203	the ready queue by calling the ready method.	338	by calling the ready method.
204		339
205	The coderef you submit MUST NOT be a closure that refers to variables	340	See C<async> for additional discussion.
206	in an outer scope. This does NOT work. Pass arguments into it instead.
207		341
208	=cut	342	=cut
209		343
210	sub _newcoro {	344	sub _run_coro {
211	terminate &{+shift};	345	terminate &{+shift};
212	}	346	}
213		347
214	sub new {	348	sub new {
215	my $class = shift;	349	my $class = shift;
216	bless {
217	_coro_state => (new Coro::State $_[0] && \&_newcoro, @_),
218	}, $class;
219	}
220		350
221	=item $process->ready	351	$class->SUPER::new (\&_run_coro, @_)
		352	}
222		353
223	Put the current process into the ready queue.	354	=item $success = $coroutine->ready
224		355
225	=cut	356	Put the given coroutine into the ready queue (according to it's priority)
		357	and return true. If the coroutine is already in the ready queue, do nothing
		358	and return false.
226		359
227	sub ready {	360	=item $is_ready = $coroutine->is_ready
228	push @ready, $_[0];	361
		362	Return wether the coroutine is currently the ready queue or not,
		363
		364	=item $coroutine->cancel (arg...)
		365
		366	Terminates the given coroutine and makes it return the given arguments as
		367	status (default: the empty list). Never returns if the coroutine is the
		368	current coroutine.
		369
		370	=cut
		371
		372	sub cancel {
		373	my $self = shift;
		374	$self->{status} = [@_];
		375
		376	if ($current == $self) {
		377	push @destroy, $self;
		378	$manager->ready;
		379	&schedule while 1;
		380	} else {
		381	$self->_cancel;
		382	}
		383	}
		384
		385	=item $coroutine->join
		386
		387	Wait until the coroutine terminates and return any values given to the
		388	C<terminate> or C<cancel> functions. C<join> can be called multiple times
		389	from multiple coroutine.
		390
		391	=cut
		392
		393	sub join {
		394	my $self = shift;
		395
		396	unless ($self->{status}) {
		397	my $current = $current;
		398
		399	push @{$self->{destroy_cb}}, sub {
		400	$current->ready;
		401	undef $current;
		402	};
		403
		404	&schedule while $current;
		405	}
		406
		407	wantarray ? @{$self->{status}} : $self->{status}[0];
		408	}
		409
		410	=item $coroutine->on_destroy (\&cb)
		411
		412	Registers a callback that is called when this coroutine gets destroyed,
		413	but before it is joined. The callback gets passed the terminate arguments,
		414	if any.
		415
		416	=cut
		417
		418	sub on_destroy {
		419	my ($self, $cb) = @_;
		420
		421	push @{ $self->{destroy_cb} }, $cb;
		422	}
		423
		424	=item $oldprio = $coroutine->prio ($newprio)
		425
		426	Sets (or gets, if the argument is missing) the priority of the
		427	coroutine. Higher priority coroutines get run before lower priority
		428	coroutines. Priorities are small signed integers (currently -4 .. +3),
		429	that you can refer to using PRIO_xxx constants (use the import tag :prio
		430	to get then):
		431
		432	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
		433	3 > 1 > 0 > -1 > -3 > -4
		434
		435	# set priority to HIGH
		436	current->prio(PRIO_HIGH);
		437
		438	The idle coroutine ($Coro::idle) always has a lower priority than any
		439	existing coroutine.
		440
		441	Changing the priority of the current coroutine will take effect immediately,
		442	but changing the priority of coroutines in the ready queue (but not
		443	running) will only take effect after the next schedule (of that
		444	coroutine). This is a bug that will be fixed in some future version.
		445
		446	=item $newprio = $coroutine->nice ($change)
		447
		448	Similar to C<prio>, but subtract the given value from the priority (i.e.
		449	higher values mean lower priority, just as in unix).
		450
		451	=item $olddesc = $coroutine->desc ($newdesc)
		452
		453	Sets (or gets in case the argument is missing) the description for this
		454	coroutine. This is just a free-form string you can associate with a coroutine.
		455
		456	=cut
		457
		458	sub desc {
		459	my $old = $_[0]{desc};
		460	$_[0]{desc} = $_[1] if @_ > 1;
		461	$old;
229	}	462	}
230		463
231	=back	464	=back
232		465
		466	=head2 GLOBAL FUNCTIONS
		467
		468	=over 4
		469
		470	=item Coro::nready
		471
		472	Returns the number of coroutines that are currently in the ready state,
		473	i.e. that can be switched to. The value C<0> means that the only runnable
		474	coroutine is the currently running one, so C<cede> would have no effect,
		475	and C<schedule> would cause a deadlock unless there is an idle handler
		476	that wakes up some coroutines.
		477
		478	=item my $guard = Coro::guard { ... }
		479
		480	This creates and returns a guard object. Nothing happens until the object
		481	gets destroyed, in which case the codeblock given as argument will be
		482	executed. This is useful to free locks or other resources in case of a
		483	runtime error or when the coroutine gets canceled, as in both cases the
		484	guard block will be executed. The guard object supports only one method,
		485	C<< ->cancel >>, which will keep the codeblock from being executed.
		486
		487	Example: set some flag and clear it again when the coroutine gets canceled
		488	or the function returns:
		489
		490	sub do_something {
		491	my $guard = Coro::guard { $busy = 0 };
		492	$busy = 1;
		493
		494	# do something that requires $busy to be true
		495	}
		496
		497	=cut
		498
		499	sub guard(&) {
		500	bless \(my $cb = $_[0]), "Coro::guard"
		501	}
		502
		503	sub Coro::guard::cancel {
		504	${$_[0]} = sub { };
		505	}
		506
		507	sub Coro::guard::DESTROY {
		508	${$_[0]}->();
		509	}
		510
		511
		512	=item unblock_sub { ... }
		513
		514	This utility function takes a BLOCK or code reference and "unblocks" it,
		515	returning the new coderef. This means that the new coderef will return
		516	immediately without blocking, returning nothing, while the original code
		517	ref will be called (with parameters) from within its own coroutine.
		518
		519	The reason this function exists is that many event libraries (such as the
		520	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		521	of thread-safety). This means you must not block within event callbacks,
		522	otherwise you might suffer from crashes or worse.
		523
		524	This function allows your callbacks to block by executing them in another
		525	coroutine where it is safe to block. One example where blocking is handy
		526	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		527	disk.
		528
		529	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		530	creating event callbacks that want to block.
		531
		532	=cut
		533
		534	our @unblock_queue;
		535
		536	# we create a special coro because we want to cede,
		537	# to reduce pressure on the coro pool (because most callbacks
		538	# return immediately and can be reused) and because we cannot cede
		539	# inside an event callback.
		540	our $unblock_scheduler = new Coro sub {
		541	while () {
		542	while (my $cb = pop @unblock_queue) {
		543	# this is an inlined copy of async_pool
		544	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		545
		546	$coro->{_invoke} = $cb;
		547	$coro->ready;
		548	cede; # for short-lived callbacks, this reduces pressure on the coro pool
		549	}
		550	schedule; # sleep well
		551	}
		552	};
		553	$unblock_scheduler->desc ("[unblock_sub scheduler]");
		554
		555	sub unblock_sub(&) {
		556	my $cb = shift;
		557
		558	sub {
		559	unshift @unblock_queue, [$cb, @_];
		560	$unblock_scheduler->ready;
		561	}
		562	}
		563
		564	=back
		565
233	=cut	566	=cut
234		567
235	1;	568	1;
236		569
237	=head1 BUGS/LIMITATIONS	570	=head1 BUGS/LIMITATIONS
238		571
239	- could be faster, especially when the core would introduce special	572	- you must make very sure that no coro is still active on global
240	support for coroutines (like it does for threads).	573	destruction. very bad things might happen otherwise (usually segfaults).
241	- there is still a memleak on coroutine termination that I could not	574
242	identify. Could be as small as a single SV.
243	- this module is not well-tested.
244	- if variables or arguments "disappear" (become undef) or become
245	corrupted please contact the author so he cen iron out the
246	remaining bugs.
247	- this module is not thread-safe. You must only ever use this module from	575	- this module is not thread-safe. You should only ever use this module
248	the same thread (this requirement might be loosened in the future to	576	from the same thread (this requirement might be loosened in the future
249	allow per-thread schedulers, but Coro::State does not yet allow this).	577	to allow per-thread schedulers, but Coro::State does not yet allow
		578	this).
250		579
251	=head1 SEE ALSO	580	=head1 SEE ALSO
252		581
253	L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,	582	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.
254	L<Coro::Signal>, L<Coro::State>, L<Coro::Event>.	583
		584	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
		585
		586	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.
		587
		588	Embedding: L<Coro:MakeMaker>
255		589
256	=head1 AUTHOR	590	=head1 AUTHOR
257		591
258	Marc Lehmann <pcg@goof.com>	592	Marc Lehmann <schmorp@schmorp.de>
259	http://www.goof.com/pcg/marc/	593	http://home.schmorp.de/
260		594
261	=cut	595	=cut
262		596

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing Coro/Coro.pm (file contents): Revision 1.21 by root, Sun Jul 22 03:24:10 2001 UTC vs. Revision 1.137 by root, Wed Sep 26 19:26:48 2007 UTC

Diff Legend

Comparing Coro/Coro.pm (file contents):
Revision 1.21 by root, Sun Jul 22 03:24:10 2001 UTC vs.
Revision 1.137 by root, Wed Sep 26 19:26:48 2007 UTC