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

Comparing Coro/Coro.pm (file contents):
Revision 1.88 by root, Sun Nov 26 02:54:55 2006 UTC vs.
Revision 1.139 by root, Thu Sep 27 15:52:30 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
		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).
		34
26	In this module, coroutines are defined as "callchain + lexical variables	35	In this module, coroutines are defined as "callchain + lexical variables +
27	+ @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own	36	@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,
28	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
29	important global variables.	38	variables.
30		39
31	=cut	40	=cut
32		41
33	package Coro;	42	package Coro;
34		43
…		…
41		50
42	our $idle; # idle handler	51	our $idle; # idle handler
43	our $main; # main coroutine	52	our $main; # main coroutine
44	our $current; # current coroutine	53	our $current; # current coroutine
45		54
46	our $VERSION = '3.0';	55	our $VERSION = '3.8';
47		56
48	our @EXPORT = qw(async cede schedule terminate current);	57	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
49	our %EXPORT_TAGS = (	58	our %EXPORT_TAGS = (
50	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	59	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
51	);	60	);
52	our @EXPORT_OK = @{$EXPORT_TAGS{prio}};	61	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
53		62
54	{	63	{
55	my @async;	64	my @async;
56	my $init;	65	my $init;
57		66
58	# this way of handling attributes simply is NOT scalable ;()	67	# this way of handling attributes simply is NOT scalable ;()
59	sub import {	68	sub import {
60	no strict 'refs';	69	no strict 'refs';
61		70
62	Coro->export_to_level(1, @_);	71	Coro->export_to_level (1, @_);
63		72
64	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};	73	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
65	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {	74	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
66	my ($package, $ref) = (shift, shift);	75	my ($package, $ref) = (shift, shift);
67	my @attrs;	76	my @attrs;
…		…
99		108
100	The current coroutine (the last coroutine switched to). The initial value	109	The current coroutine (the last coroutine switched to). The initial value
101	is C<$main> (of course).	110	is C<$main> (of course).
102		111
103	This variable is B<strictly> I<read-only>. It is provided for performance	112	This variable is B<strictly> I<read-only>. It is provided for performance
104	reasons. If performance is not essentiel you are encouraged to use the	113	reasons. If performance is not essential you are encouraged to use the
105	C<Coro::current> function instead.	114	C<Coro::current> function instead.
106		115
107	=cut	116	=cut
108		117
		118	$main->{desc} = "[main::]";
		119
109	# maybe some other module used Coro::Specific before...	120	# maybe some other module used Coro::Specific before...
110	if ($current) {
111	$main->{specific} = $current->{specific};	121	$main->{specific} = $current->{specific}
112	}	122	if $current;
113		123
114	$current = $main;	124	_set_current $main;
115		125
116	sub current() { $current }	126	sub current() { $current }
117		127
118	=item $idle	128	=item $idle
119		129
120	A callback that is called whenever the scheduler finds no ready coroutines	130	A callback that is called whenever the scheduler finds no ready coroutines
121	to run. The default implementation prints "FATAL: deadlock detected" and	131	to run. The default implementation prints "FATAL: deadlock detected" and
122	exits.	132	exits, because the program has no other way to continue.
123		133
124	This hook is overwritten by modules such as C<Coro::Timer> and	134	This hook is overwritten by modules such as C<Coro::Timer> and
125	C<Coro::Event> to wait on an external event that hopefully wakes up some	135	C<Coro::Event> to wait on an external event that hopefully wake up a
126	coroutine.	136	coroutine so the scheduler can run it.
		137
		138	Please note that if your callback recursively invokes perl (e.g. for event
		139	handlers), then it must be prepared to be called recursively.
127		140
128	=cut	141	=cut
129		142
130	$idle = sub {	143	$idle = sub {
131	print STDERR "FATAL: deadlock detected\n";	144	require Carp;
132	exit (51);	145	Carp::croak ("FATAL: deadlock detected");
133	};	146	};
		147
		148	sub _cancel {
		149	my ($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 $self->{destroy_cb}) \|\| []};
		158	}
		159
		160	sub _do_trace_sub {
		161	&{$current->{_trace_sub_cb}}
		162	}
		163
		164	sub _do_trace_line {
		165	&{$current->{_trace_line_cb}}
		166	}
134		167
135	# this coroutine is necessary because a coroutine	168	# this coroutine is necessary because a coroutine
136	# cannot destroy itself.	169	# cannot destroy itself.
137	my @destroy;	170	my @destroy;
		171	my $manager;
		172
138	my $manager; $manager = new Coro sub {	173	$manager = new Coro sub {
139	while () {	174	while () {
140	# by overwriting the state object with the manager we destroy it	175	(shift @destroy)->_cancel
141	# while still being able to schedule this coroutine (in case it has
142	# been readied multiple times. this is harmless since the manager
143	# can be called as many times as neccessary and will always
144	# remove itself from the runqueue
145	while (@destroy) {	176	while @destroy;
146	my $coro = pop @destroy;
147	$coro->{status} \|\|= [];
148	$_->ready for @{delete $coro->{join} \|\| []};
149		177
150	# the next line destroys the coro state, but keeps the
151	# process itself intact (we basically make it a zombie
152	# process that always runs the manager thread, so it's possible
153	# to transfer() to this process).
154	$coro->_clone_state_from ($manager);
155	}
156	&schedule;	178	&schedule;
157	}	179	}
158	};	180	};
		181	$manager->desc ("[coro manager]");
		182	$manager->prio (PRIO_MAX);
159		183
160	# static methods. not really.	184	# static methods. not really.
161		185
162	=back	186	=back
163		187
164	=head2 STATIC METHODS	188	=head2 STATIC METHODS
165		189
166	Static methods are actually functions that operate on the current process only.	190	Static methods are actually functions that operate on the current coroutine only.
167		191
168	=over 4	192	=over 4
169		193
170	=item async { ... } [@args...]	194	=item async { ... } [@args...]
171		195
172	Create a new asynchronous process and return it's process object	196	Create a new asynchronous coroutine and return it's coroutine object
173	(usually unused). When the sub returns the new process is automatically	197	(usually unused). When the sub returns the new coroutine is automatically
174	terminated.	198	terminated.
175		199
176	When the coroutine dies, the program will exit, just as in the main	200	Calling C<exit> in a coroutine will do the same as calling exit outside
177	program.	201	the coroutine. Likewise, when the coroutine dies, the program will exit,
		202	just as it would in the main program.
178		203
179	# create a new coroutine that just prints its arguments	204	# create a new coroutine that just prints its arguments
180	async {	205	async {
181	print "@_\n";	206	print "@_\n";
182	} 1,2,3,4;	207	} 1,2,3,4;
183		208
184	=cut	209	=cut
185		210
186	sub async(&@) {	211	sub async(&@) {
187	my $pid = new Coro @_;	212	my $coro = new Coro @_;
188	$pid->ready;	213	$coro->ready;
189	$pid	214	$coro
		215	}
		216
		217	=item async_pool { ... } [@args...]
		218
		219	Similar to C<async>, but uses a coroutine pool, so you should not call
		220	terminate or join (although you are allowed to), and you get a coroutine
		221	that might have executed other code already (which can be good or bad :).
		222
		223	Also, the block is executed in an C<eval> context and a warning will be
		224	issued in case of an exception instead of terminating the program, as
		225	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
		226	will not work in the expected way, unless you call terminate or cancel,
		227	which somehow defeats the purpose of pooling.
		228
		229	The priority will be reset to C<0> after each job, otherwise the coroutine
		230	will be re-used "as-is".
		231
		232	The pool size is limited to 8 idle coroutines (this can be adjusted by
		233	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
		234	required.
		235
		236	If you are concerned about pooled coroutines growing a lot because a
		237	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
		238	{ terminate }> once per second or so to slowly replenish the pool. In
		239	addition to that, when the stacks used by a handler grows larger than 16kb
		240	(adjustable with $Coro::POOL_RSS) it will also exit.
		241
		242	=cut
		243
		244	our $POOL_SIZE = 8;
		245	our $POOL_RSS = 16 * 1024;
		246	our @async_pool;
		247
		248	sub pool_handler {
		249	my $cb;
		250
		251	while () {
		252	eval {
		253	while () {
		254	_pool_1 $cb;
		255	&$cb;
		256	_pool_2 $cb;
		257	&schedule;
		258	}
		259	};
		260
		261	last if $@ eq "\3terminate\2\n";
		262	warn $@ if $@;
		263	}
		264	}
		265
		266	sub async_pool(&@) {
		267	# this is also inlined into the unlock_scheduler
		268	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		269
		270	$coro->{_invoke} = [@_];
		271	$coro->ready;
		272
		273	$coro
190	}	274	}
191		275
192	=item schedule	276	=item schedule
193		277
194	Calls the scheduler. Please note that the current process will not be put	278	Calls the scheduler. Please note that the current coroutine will not be put
195	into the ready queue, so calling this function usually means you will	279	into the ready queue, so calling this function usually means you will
196	never be called again.	280	never be called again unless something else (e.g. an event handler) calls
		281	ready.
197		282
198	=cut	283	The canonical way to wait on external events is this:
		284
		285	{
		286	# remember current coroutine
		287	my $current = $Coro::current;
		288
		289	# register a hypothetical event handler
		290	on_event_invoke sub {
		291	# wake up sleeping coroutine
		292	$current->ready;
		293	undef $current;
		294	};
		295
		296	# call schedule until event occurred.
		297	# in case we are woken up for other reasons
		298	# (current still defined), loop.
		299	Coro::schedule while $current;
		300	}
199		301
200	=item cede	302	=item cede
201		303
202	"Cede" to other processes. This function puts the current process into the	304	"Cede" to other coroutines. This function puts the current coroutine into the
203	ready queue and calls C<schedule>, which has the effect of giving up the	305	ready queue and calls C<schedule>, which has the effect of giving up the
204	current "timeslice" to other coroutines of the same or higher priority.	306	current "timeslice" to other coroutines of the same or higher priority.
205		307
206	=cut	308	Returns true if at least one coroutine switch has happened.
		309
		310	=item Coro::cede_notself
		311
		312	Works like cede, but is not exported by default and will cede to any
		313	coroutine, regardless of priority, once.
		314
		315	Returns true if at least one coroutine switch has happened.
207		316
208	=item terminate [arg...]	317	=item terminate [arg...]
209		318
210	Terminates the current process with the given status values (see L<cancel>).	319	Terminates the current coroutine with the given status values (see L<cancel>).
211		320
212	=cut	321	=cut
213		322
214	sub terminate {	323	sub terminate {
215	$current->cancel (@_);	324	$current->cancel (@_);
…		…
217		326
218	=back	327	=back
219		328
220	# dynamic methods	329	# dynamic methods
221		330
222	=head2 PROCESS METHODS	331	=head2 COROUTINE METHODS
223		332
224	These are the methods you can call on process objects.	333	These are the methods you can call on coroutine objects.
225		334
226	=over 4	335	=over 4
227		336
228	=item new Coro \&sub [, @args...]	337	=item new Coro \&sub [, @args...]
229		338
230	Create a new process and return it. When the sub returns the process	339	Create a new coroutine and return it. When the sub returns the coroutine
231	automatically terminates as if C<terminate> with the returned values were	340	automatically terminates as if C<terminate> with the returned values were
232	called. To make the process run you must first put it into the ready queue	341	called. To make the coroutine run you must first put it into the ready queue
233	by calling the ready method.	342	by calling the ready method.
234		343
235	=cut	344	See C<async> for additional discussion.
236		345
		346	=cut
		347
237	sub _new_coro {	348	sub _run_coro {
238	terminate &{+shift};	349	terminate &{+shift};
239	}	350	}
240		351
241	sub new {	352	sub new {
242	my $class = shift;	353	my $class = shift;
243		354
244	$class->SUPER::new (\&_new_coro, @_)	355	$class->SUPER::new (\&_run_coro, @_)
245	}	356	}
246		357
247	=item $process->ready	358	=item $success = $coroutine->ready
248		359
249	Put the given process into the ready queue.	360	Put the given coroutine into the ready queue (according to it's priority)
		361	and return true. If the coroutine is already in the ready queue, do nothing
		362	and return false.
250		363
251	=cut	364	=item $is_ready = $coroutine->is_ready
252		365
		366	Return wether the coroutine is currently the ready queue or not,
		367
253	=item $process->cancel (arg...)	368	=item $coroutine->cancel (arg...)
254		369
255	Terminates the given process and makes it return the given arguments as	370	Terminates the given coroutine and makes it return the given arguments as
256	status (default: the empty list).	371	status (default: the empty list). Never returns if the coroutine is the
		372	current coroutine.
257		373
258	=cut	374	=cut
259		375
260	sub cancel {	376	sub cancel {
261	my $self = shift;	377	my $self = shift;
262	$self->{status} = [@_];	378	$self->{status} = [@_];
		379
		380	if ($current == $self) {
263	push @destroy, $self;	381	push @destroy, $self;
264	$manager->ready;	382	$manager->ready;
265	&schedule if $current == $self;	383	&schedule while 1;
		384	} else {
		385	$self->_cancel;
		386	}
266	}	387	}
267		388
268	=item $process->join	389	=item $coroutine->join
269		390
270	Wait until the coroutine terminates and return any values given to the	391	Wait until the coroutine terminates and return any values given to the
271	C<terminate> or C<cancel> functions. C<join> can be called multiple times	392	C<terminate> or C<cancel> functions. C<join> can be called multiple times
272	from multiple processes.	393	from multiple coroutine.
273		394
274	=cut	395	=cut
275		396
276	sub join {	397	sub join {
277	my $self = shift;	398	my $self = shift;
		399
278	unless ($self->{status}) {	400	unless ($self->{status}) {
279	push @{$self->{join}}, $current;	401	my $current = $current;
280	&schedule;	402
		403	push @{$self->{destroy_cb}}, sub {
		404	$current->ready;
		405	undef $current;
		406	};
		407
		408	&schedule while $current;
281	}	409	}
		410
282	wantarray ? @{$self->{status}} : $self->{status}[0];	411	wantarray ? @{$self->{status}} : $self->{status}[0];
283	}	412	}
284		413
		414	=item $coroutine->on_destroy (\&cb)
		415
		416	Registers a callback that is called when this coroutine gets destroyed,
		417	but before it is joined. The callback gets passed the terminate arguments,
		418	if any.
		419
		420	=cut
		421
		422	sub on_destroy {
		423	my ($self, $cb) = @_;
		424
		425	push @{ $self->{destroy_cb} }, $cb;
		426	}
		427
285	=item $oldprio = $process->prio ($newprio)	428	=item $oldprio = $coroutine->prio ($newprio)
286		429
287	Sets (or gets, if the argument is missing) the priority of the	430	Sets (or gets, if the argument is missing) the priority of the
288	process. Higher priority processes get run before lower priority	431	coroutine. Higher priority coroutines get run before lower priority
289	processes. Priorities are small signed integers (currently -4 .. +3),	432	coroutines. Priorities are small signed integers (currently -4 .. +3),
290	that you can refer to using PRIO_xxx constants (use the import tag :prio	433	that you can refer to using PRIO_xxx constants (use the import tag :prio
291	to get then):	434	to get then):
292		435
293	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN	436	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
294	3 > 1 > 0 > -1 > -3 > -4	437	3 > 1 > 0 > -1 > -3 > -4
…		…
297	current->prio(PRIO_HIGH);	440	current->prio(PRIO_HIGH);
298		441
299	The idle coroutine ($Coro::idle) always has a lower priority than any	442	The idle coroutine ($Coro::idle) always has a lower priority than any
300	existing coroutine.	443	existing coroutine.
301		444
302	Changing the priority of the current process will take effect immediately,	445	Changing the priority of the current coroutine will take effect immediately,
303	but changing the priority of processes in the ready queue (but not	446	but changing the priority of coroutines in the ready queue (but not
304	running) will only take effect after the next schedule (of that	447	running) will only take effect after the next schedule (of that
305	process). This is a bug that will be fixed in some future version.	448	coroutine). This is a bug that will be fixed in some future version.
306		449
307	=item $newprio = $process->nice ($change)	450	=item $newprio = $coroutine->nice ($change)
308		451
309	Similar to C<prio>, but subtract the given value from the priority (i.e.	452	Similar to C<prio>, but subtract the given value from the priority (i.e.
310	higher values mean lower priority, just as in unix).	453	higher values mean lower priority, just as in unix).
311		454
312	=item $olddesc = $process->desc ($newdesc)	455	=item $olddesc = $coroutine->desc ($newdesc)
313		456
314	Sets (or gets in case the argument is missing) the description for this	457	Sets (or gets in case the argument is missing) the description for this
315	process. This is just a free-form string you can associate with a process.	458	coroutine. This is just a free-form string you can associate with a coroutine.
316		459
317	=cut	460	=cut
318		461
319	sub desc {	462	sub desc {
320	my $old = $_[0]{desc};	463	my $old = $_[0]{desc};
…		…
322	$old;	465	$old;
323	}	466	}
324		467
325	=back	468	=back
326		469
		470	=head2 GLOBAL FUNCTIONS
		471
		472	=over 4
		473
		474	=item Coro::nready
		475
		476	Returns the number of coroutines that are currently in the ready state,
		477	i.e. that can be switched to. The value C<0> means that the only runnable
		478	coroutine is the currently running one, so C<cede> would have no effect,
		479	and C<schedule> would cause a deadlock unless there is an idle handler
		480	that wakes up some coroutines.
		481
		482	=item my $guard = Coro::guard { ... }
		483
		484	This creates and returns a guard object. Nothing happens until the object
		485	gets destroyed, in which case the codeblock given as argument will be
		486	executed. This is useful to free locks or other resources in case of a
		487	runtime error or when the coroutine gets canceled, as in both cases the
		488	guard block will be executed. The guard object supports only one method,
		489	C<< ->cancel >>, which will keep the codeblock from being executed.
		490
		491	Example: set some flag and clear it again when the coroutine gets canceled
		492	or the function returns:
		493
		494	sub do_something {
		495	my $guard = Coro::guard { $busy = 0 };
		496	$busy = 1;
		497
		498	# do something that requires $busy to be true
		499	}
		500
		501	=cut
		502
		503	sub guard(&) {
		504	bless \(my $cb = $_[0]), "Coro::guard"
		505	}
		506
		507	sub Coro::guard::cancel {
		508	${$_[0]} = sub { };
		509	}
		510
		511	sub Coro::guard::DESTROY {
		512	${$_[0]}->();
		513	}
		514
		515
		516	=item unblock_sub { ... }
		517
		518	This utility function takes a BLOCK or code reference and "unblocks" it,
		519	returning the new coderef. This means that the new coderef will return
		520	immediately without blocking, returning nothing, while the original code
		521	ref will be called (with parameters) from within its own coroutine.
		522
		523	The reason this function exists is that many event libraries (such as the
		524	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		525	of thread-safety). This means you must not block within event callbacks,
		526	otherwise you might suffer from crashes or worse.
		527
		528	This function allows your callbacks to block by executing them in another
		529	coroutine where it is safe to block. One example where blocking is handy
		530	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		531	disk.
		532
		533	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		534	creating event callbacks that want to block.
		535
		536	=cut
		537
		538	our @unblock_queue;
		539
		540	# we create a special coro because we want to cede,
		541	# to reduce pressure on the coro pool (because most callbacks
		542	# return immediately and can be reused) and because we cannot cede
		543	# inside an event callback.
		544	our $unblock_scheduler = new Coro sub {
		545	while () {
		546	while (my $cb = pop @unblock_queue) {
		547	# this is an inlined copy of async_pool
		548	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		549
		550	$coro->{_invoke} = $cb;
		551	$coro->ready;
		552	cede; # for short-lived callbacks, this reduces pressure on the coro pool
		553	}
		554	schedule; # sleep well
		555	}
		556	};
		557	$unblock_scheduler->desc ("[unblock_sub scheduler]");
		558
		559	sub unblock_sub(&) {
		560	my $cb = shift;
		561
		562	sub {
		563	unshift @unblock_queue, [$cb, @_];
		564	$unblock_scheduler->ready;
		565	}
		566	}
		567
		568	=back
		569
327	=cut	570	=cut
328		571
329	1;	572	1;
330		573
331	=head1 BUGS/LIMITATIONS	574	=head1 BUGS/LIMITATIONS
332		575
333	- you must make very sure that no coro is still active on global	576	- you must make very sure that no coro is still active on global
334	destruction. very bad things might happen otherwise (usually segfaults).	577	destruction. very bad things might happen otherwise (usually segfaults).
335		578
336	- this module is not thread-safe. You should only ever use this module	579	- this module is not thread-safe. You should only ever use this module
337	from the same thread (this requirement might be losened in the future	580	from the same thread (this requirement might be loosened in the future
338	to allow per-thread schedulers, but Coro::State does not yet allow	581	to allow per-thread schedulers, but Coro::State does not yet allow
339	this).	582	this).
340		583
341	=head1 SEE ALSO	584	=head1 SEE ALSO
342		585

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Comparing Coro/Coro.pm (file contents): Revision 1.88 by root, Sun Nov 26 02:54:55 2006 UTC vs. Revision 1.139 by root, Thu Sep 27 15:52:30 2007 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.88 by root, Sun Nov 26 02:54:55 2006 UTC vs.
Revision 1.139 by root, Thu Sep 27 15:52:30 2007 UTC