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

Comparing Coro/Coro.pm (file contents):
Revision 1.89 by root, Mon Nov 27 02:01:33 2006 UTC vs.
Revision 1.186 by root, Sun May 25 01:32:36 2008 UTC

…		…
2		2
3	Coro - coroutine process abstraction	3	Coro - coroutine process abstraction
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use Coro;	7	use Coro;
8		8
9	async {	9	async {
10	# some asynchronous thread of execution	10	# some asynchronous thread of execution
		11	print "2\n";
		12	cede; # yield back to main
		13	print "4\n";
11	};	14	};
12		15	print "1\n";
13	# alternatively create an async process like this:	16	cede; # yield to coroutine
14		17	print "3\n";
15	sub some_func : Coro {	18	cede; # and again
16	# some more async code	19
17	}	20	# use locking
18		21	my $lock = new Coro::Semaphore;
19	cede;	22	my $locked;
		23
		24	$lock->down;
		25	$locked = 1;
		26	$lock->up;
20		27
21	=head1 DESCRIPTION	28	=head1 DESCRIPTION
22		29
23	This module collection manages coroutines. Coroutines are similar to	30	This module collection manages coroutines. Coroutines are similar to
24	threads but don't run in parallel.	31	threads but don't (in general) run in parallel at the same time even
		32	on SMP machines. The specific flavor of coroutine used in this module
		33	also guarantees you that it will not switch between coroutines unless
		34	necessary, at easily-identified points in your program, so locking and
		35	parallel access are rarely an issue, making coroutine programming much
		36	safer and easier than threads programming.
25		37
		38	Unlike a normal perl program, however, coroutines allow you to have
		39	multiple running interpreters that share data, which is especially useful
		40	to code pseudo-parallel processes and for event-based programming, such as
		41	multiple HTTP-GET requests running concurrently. See L<Coro::AnyEvent> to
		42	learn more.
		43
		44	Coroutines are also useful because Perl has no support for threads (the so
		45	called "threads" that perl offers are nothing more than the (bad) process
		46	emulation coming from the Windows platform: On standard operating systems
		47	they serve no purpose whatsoever, except by making your programs slow and
		48	making them use a lot of memory. Best disable them when building perl, or
		49	aks your software vendor/distributor to do it for you).
		50
26	In this module, coroutines are defined as "callchain + lexical variables	51	In this module, coroutines are defined as "callchain + lexical variables +
27	+ @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own	52	@_ + $_ + $@ + $/ + 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	53	its own set of lexicals and its own set of perls most important global
29	important global variables.	54	variables (see L<Coro::State> for more configuration).
30		55
31	=cut	56	=cut
32		57
33	package Coro;	58	package Coro;
34		59
…		…
41		66
42	our $idle; # idle handler	67	our $idle; # idle handler
43	our $main; # main coroutine	68	our $main; # main coroutine
44	our $current; # current coroutine	69	our $current; # current coroutine
45		70
46	our $VERSION = '3.0';	71	our $VERSION = '4.72';
47		72
48	our @EXPORT = qw(async cede schedule terminate current);	73	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
49	our %EXPORT_TAGS = (	74	our %EXPORT_TAGS = (
50	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	75	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
51	);	76	);
52	our @EXPORT_OK = @{$EXPORT_TAGS{prio}};	77	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
53
54	{
55	my @async;
56	my $init;
57
58	# this way of handling attributes simply is NOT scalable ;()
59	sub import {
60	no strict 'refs';
61
62	Coro->export_to_level(1, @_);
63
64	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
65	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
66	my ($package, $ref) = (shift, shift);
67	my @attrs;
68	for (@_) {
69	if ($_ eq "Coro") {
70	push @async, $ref;
71	unless ($init++) {
72	eval q{
73	sub INIT {
74	&async(pop @async) while @async;
75	}
76	};
77	}
78	} else {
79	push @attrs, $_;
80	}
81	}
82	return $old ? $old->($package, $ref, @attrs) : @attrs;
83	};
84	}
85
86	}
87		78
88	=over 4	79	=over 4
89		80
90	=item $main	81	=item $Coro::main
91		82
92	This coroutine represents the main program.	83	This variable stores the coroutine object that represents the main
		84	program. While you cna C<ready> it and do most other things you can do to
		85	coroutines, it is mainly useful to compare again C<$Coro::current>, to see
		86	wether you are running in the main program or not.
93		87
94	=cut	88	=cut
95		89
96	$main = new Coro;	90	$main = new Coro;
97		91
98	=item $current (or as function: current)	92	=item $Coro::current
99		93
100	The current coroutine (the last coroutine switched to). The initial value	94	The coroutine object representing the current coroutine (the last
		95	coroutine that the Coro scheduler switched to). The initial value is
101	is C<$main> (of course).	96	C<$main> (of course).
102		97
103	This variable is B<strictly> I<read-only>. It is provided for performance	98	This variable is B<strictly> I<read-only>. You can take copies of the
104	reasons. If performance is not essentiel you are encouraged to use the	99	value stored in it and use it as any other coroutine object, but you must
105	C<Coro::current> function instead.	100	not otherwise modify the variable itself.
106		101
107	=cut	102	=cut
		103
		104	$main->{desc} = "[main::]";
108		105
109	# maybe some other module used Coro::Specific before...	106	# maybe some other module used Coro::Specific before...
110	if ($current) {
111	$main->{specific} = $current->{specific};	107	$main->{_specific} = $current->{_specific}
112	}	108	if $current;
113		109
114	$current = $main;	110	_set_current $main;
115		111
116	sub current() { $current }	112	sub current() { $current } # [DEPRECATED]
117		113
118	=item $idle	114	=item $Coro::idle
119		115
120	A callback that is called whenever the scheduler finds no ready coroutines	116	This variable is mainly useful to integrate Coro into event loops. It is
121	to run. The default implementation prints "FATAL: deadlock detected" and	117	usually better to rely on L<Coro::AnyEvent> or LC<Coro::EV>, as this is
122	exits.	118	pretty low-level functionality.
		119
		120	This variable stores a callback that is called whenever the scheduler
		121	finds no ready coroutines to run. The default implementation prints
		122	"FATAL: deadlock detected" and exits, because the program has no other way
		123	to continue.
123		124
124	This hook is overwritten by modules such as C<Coro::Timer> and	125	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	126	C<Coro::AnyEvent> to wait on an external event that hopefully wake up a
126	coroutine.	127	coroutine so the scheduler can run it.
		128
		129	Note that the callback I<must not>, under any circumstances, block
		130	the current coroutine. Normally, this is achieved by having an "idle
		131	coroutine" that calls the event loop and then blocks again, and then
		132	readying that coroutine in the idle handler.
		133
		134	See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this
		135	technique.
		136
		137	Please note that if your callback recursively invokes perl (e.g. for event
		138	handlers), then it must be prepared to be called recursively itself.
127		139
128	=cut	140	=cut
129		141
130	$idle = sub {	142	$idle = sub {
131	print STDERR "FATAL: deadlock detected\n";	143	require Carp;
132	exit (51);	144	Carp::croak ("FATAL: deadlock detected");
133	};	145	};
		146
		147	sub _cancel {
		148	my ($self) = @_;
		149
		150	# free coroutine data and mark as destructed
		151	$self->_destroy
		152	or return;
		153
		154	# call all destruction callbacks
		155	$_->(@{$self->{_status}})
		156	for @{(delete $self->{_on_destroy}) \|\| []};
		157	}
134		158
135	# this coroutine is necessary because a coroutine	159	# this coroutine is necessary because a coroutine
136	# cannot destroy itself.	160	# cannot destroy itself.
137	my @destroy;	161	my @destroy;
		162	my $manager;
		163
138	my $manager; $manager = new Coro sub {	164	$manager = new Coro sub {
139	while () {	165	while () {
140	# by overwriting the state object with the manager we destroy it	166	(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) {	167	while @destroy;
146	my $coro = pop @destroy;
147	$coro->{status} \|\|= [];
148	$_->ready for @{delete $coro->{join} \|\| []};
149		168
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;	169	&schedule;
157	}	170	}
158	};	171	};
159		172	$manager->desc ("[coro manager]");
160	# static methods. not really.	173	$manager->prio (PRIO_MAX);
161		174
162	=back	175	=back
163		176
164	=head2 STATIC METHODS	177	=head2 SIMPLE COROUTINE CREATION
165
166	Static methods are actually functions that operate on the current process only.
167		178
168	=over 4	179	=over 4
169		180
170	=item async { ... } [@args...]	181	=item async { ... } [@args...]
171		182
172	Create a new asynchronous process and return it's process object	183	Create a new coroutine and return it's coroutine object (usually
173	(usually unused). When the sub returns the new process is automatically	184	unused). The coroutine will be put into the ready queue, so
		185	it will start running automatically on the next scheduler run.
		186
		187	The first argument is a codeblock/closure that should be executed in the
		188	coroutine. When it returns argument returns the coroutine is automatically
174	terminated.	189	terminated.
175		190
176	Calling C<exit> in a coroutine will not work correctly, so do not do that.	191	The remaining arguments are passed as arguments to the closure.
177		192
178	When the coroutine dies, the program will exit, just as in the main	193	See the C<Coro::State::new> constructor for info about the coroutine
179	program.	194	environment in which coroutines are executed.
180		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.
		199
		200	If you do not want that, you can provide a default C<die> handler, or
		201	simply avoid dieing (by use of C<eval>).
		202
181	# create a new coroutine that just prints its arguments	203	Example: Create a new coroutine that just prints its arguments.
		204
182	async {	205	async {
183	print "@_\n";	206	print "@_\n";
184	} 1,2,3,4;	207	} 1,2,3,4;
185		208
186	=cut	209	=cut
187		210
188	sub async(&@) {	211	sub async(&@) {
189	my $pid = new Coro @_;	212	my $coro = new Coro @_;
190	$pid->ready;	213	$coro->ready;
191	$pid	214	$coro
192	}	215	}
		216
		217	=item async_pool { ... } [@args...]
		218
		219	Similar to C<async>, but uses a coroutine pool, so you should not call
		220	terminate or join on it (although you are allowed to), and you get a
		221	coroutine that might have executed other code already (which can be good
		222	or bad :).
		223
		224	On the plus side, this function is faster than creating (and destroying)
		225	a completely new coroutine, so if you need a lot of generic coroutines in
		226	quick successsion, use C<async_pool>, not C<async>.
		227
		228	The code block is executed in an C<eval> context and a warning will be
		229	issued in case of an exception instead of terminating the program, as
		230	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
		231	will not work in the expected way, unless you call terminate or cancel,
		232	which somehow defeats the purpose of pooling (but is fine in the
		233	exceptional case).
		234
		235	The priority will be reset to C<0> after each run, tracing will be
		236	disabled, the description will be reset and the default output filehandle
		237	gets restored, so you can change all these. Otherwise the coroutine will
		238	be re-used "as-is": most notably if you change other per-coroutine global
		239	stuff such as C<$/> you I<must needs> to revert that change, which is most
		240	simply done by using local as in: C< local $/ >.
		241
		242	The pool size is limited to C<8> idle coroutines (this can be adjusted by
		243	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
		244	required.
		245
		246	If you are concerned about pooled coroutines growing a lot because a
		247	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
		248	{ terminate }> once per second or so to slowly replenish the pool. In
		249	addition to that, when the stacks used by a handler grows larger than 16kb
		250	(adjustable via $Coro::POOL_RSS) it will also be destroyed.
		251
		252	=cut
		253
		254	our $POOL_SIZE = 8;
		255	our $POOL_RSS = 16 * 1024;
		256	our @async_pool;
		257
		258	sub pool_handler {
		259	my $cb;
		260
		261	while () {
		262	eval {
		263	while () {
		264	_pool_1 $cb;
		265	&$cb;
		266	_pool_2 $cb;
		267	&schedule;
		268	}
		269	};
		270
		271	last if $@ eq "\3async_pool terminate\2\n";
		272	warn $@ if $@;
		273	}
		274	}
		275
		276	sub async_pool(&@) {
		277	# this is also inlined into the unlock_scheduler
		278	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		279
		280	$coro->{_invoke} = [@_];
		281	$coro->ready;
		282
		283	$coro
		284	}
		285
		286	=back
		287
		288	=head2 STATIC METHODS
		289
		290	Static methods are actually functions that operate on the current coroutine.
		291
		292	=over 4
193		293
194	=item schedule	294	=item schedule
195		295
196	Calls the scheduler. Please note that the current process will not be put	296	Calls the scheduler. The scheduler will find the next coroutine that is
		297	to be run from the ready queue and switches to it. The next coroutine
		298	to be run is simply the one with the highest priority that is longest
		299	in its ready queue. If there is no coroutine ready, it will clal the
		300	C<$Coro::idle> hook.
		301
		302	Please note that the current coroutine will I<not> be put into the ready
197	into the ready queue, so calling this function usually means you will	303	queue, so calling this function usually means you will never be called
198	never be called again.	304	again unless something else (e.g. an event handler) calls C<< ->ready >>,
		305	thus waking you up.
199		306
200	=cut	307	This makes C<schedule> I<the> generic method to use to block the current
		308	coroutine and wait for events: first you remember the current coroutine in
		309	a variable, then arrange for some callback of yours to call C<< ->ready
		310	>> on that once some event happens, and last you call C<schedule> to put
		311	yourself to sleep. Note that a lot of things can wake your coroutine up,
		312	so you need to check wether the event indeed happened, e.g. by storing the
		313	status in a variable.
		314
		315	The canonical way to wait on external events is this:
		316
		317	{
		318	# remember current coroutine
		319	my $current = $Coro::current;
		320
		321	# register a hypothetical event handler
		322	on_event_invoke sub {
		323	# wake up sleeping coroutine
		324	$current->ready;
		325	undef $current;
		326	};
		327
		328	# call schedule until event occurred.
		329	# in case we are woken up for other reasons
		330	# (current still defined), loop.
		331	Coro::schedule while $current;
		332	}
201		333
202	=item cede	334	=item cede
203		335
204	"Cede" to other processes. This function puts the current process into the	336	"Cede" to other coroutines. This function puts the current coroutine into
205	ready queue and calls C<schedule>, which has the effect of giving up the	337	the ready queue and calls C<schedule>, which has the effect of giving
206	current "timeslice" to other coroutines of the same or higher priority.	338	up the current "timeslice" to other coroutines of the same or higher
		339	priority. Once your coroutine gets its turn again it will automatically be
		340	resumed.
207		341
208	=cut	342	This function is often called C<yield> in other languages.
		343
		344	=item Coro::cede_notself
		345
		346	Works like cede, but is not exported by default and will cede to I<any>
		347	coroutine, regardless of priority. This is useful sometimes to ensure
		348	progress is made.
209		349
210	=item terminate [arg...]	350	=item terminate [arg...]
211		351
212	Terminates the current process with the given status values (see L<cancel>).	352	Terminates the current coroutine with the given status values (see L<cancel>).
		353
		354	=item killall
		355
		356	Kills/terminates/cancels all coroutines except the currently running
		357	one. This is useful after a fork, either in the child or the parent, as
		358	usually only one of them should inherit the running coroutines.
		359
		360	Note that while this will try to free some of the main programs resources,
		361	you cnanot free all of them, so if a coroutine that is not the main
		362	program calls this function, there will be some one-time resource leak.
213		363
214	=cut	364	=cut
215		365
216	sub terminate {	366	sub terminate {
217	$current->cancel (@_);	367	$current->cancel (@_);
218	}	368	}
219		369
		370	sub killall {
		371	for (Coro::State::list) {
		372	$_->cancel
		373	if $_ != $current && UNIVERSAL::isa $_, "Coro";
		374	}
		375	}
		376
220	=back	377	=back
221		378
222	# dynamic methods
223
224	=head2 PROCESS METHODS	379	=head2 COROUTINE METHODS
225		380
226	These are the methods you can call on process objects.	381	These are the methods you can call on coroutine objects (or to create
		382	them).
227		383
228	=over 4	384	=over 4
229		385
230	=item new Coro \&sub [, @args...]	386	=item new Coro \&sub [, @args...]
231		387
232	Create a new process and return it. When the sub returns the process	388	Create a new coroutine and return it. When the sub returns, the coroutine
233	automatically terminates as if C<terminate> with the returned values were	389	automatically terminates as if C<terminate> with the returned values were
234	called. To make the process run you must first put it into the ready queue	390	called. To make the coroutine run you must first put it into the ready
235	by calling the ready method.	391	queue by calling the ready method.
236		392
237	Calling C<exit> in a coroutine will not work correctly, so do not do that.	393	See C<async> and C<Coro::State::new> for additional info about the
		394	coroutine environment.
238		395
239	=cut	396	=cut
240		397
241	sub _new_coro {	398	sub _run_coro {
242	terminate &{+shift};	399	terminate &{+shift};
243	}	400	}
244		401
245	sub new {	402	sub new {
246	my $class = shift;	403	my $class = shift;
247		404
248	$class->SUPER::new (\&_new_coro, @_)	405	$class->SUPER::new (\&_run_coro, @_)
249	}	406	}
250		407
251	=item $process->ready	408	=item $success = $coroutine->ready
252		409
253	Put the given process into the ready queue.	410	Put the given coroutine into the end of its ready queue (there is one
		411	queue for each priority) and return true. If the coroutine is already in
		412	the ready queue, do nothing and return false.
254		413
255	=cut	414	This ensures that the scheduler will resume this coroutine automatically
		415	once all the coroutines of higher priority and all coroutines of the same
		416	priority that were put into the ready queue earlier have been resumed.
256		417
		418	=item $is_ready = $coroutine->is_ready
		419
		420	Return wether the coroutine is currently the ready queue or not,
		421
257	=item $process->cancel (arg...)	422	=item $coroutine->cancel (arg...)
258		423
259	Terminates the given process and makes it return the given arguments as	424	Terminates the given coroutine and makes it return the given arguments as
260	status (default: the empty list).	425	status (default: the empty list). Never returns if the coroutine is the
		426	current coroutine.
261		427
262	=cut	428	=cut
263		429
264	sub cancel {	430	sub cancel {
265	my $self = shift;	431	my $self = shift;
266	$self->{status} = [@_];	432	$self->{_status} = [@_];
		433
		434	if ($current == $self) {
267	push @destroy, $self;	435	push @destroy, $self;
268	$manager->ready;	436	$manager->ready;
269	&schedule if $current == $self;	437	&schedule while 1;
		438	} else {
		439	$self->_cancel;
		440	}
270	}	441	}
271		442
272	=item $process->join	443	=item $coroutine->join
273		444
274	Wait until the coroutine terminates and return any values given to the	445	Wait until the coroutine terminates and return any values given to the
275	C<terminate> or C<cancel> functions. C<join> can be called multiple times	446	C<terminate> or C<cancel> functions. C<join> can be called concurrently
276	from multiple processes.	447	from multiple coroutines, and all will be resumed and given the status
		448	return once the C<$coroutine> terminates.
277		449
278	=cut	450	=cut
279		451
280	sub join {	452	sub join {
281	my $self = shift;	453	my $self = shift;
		454
282	unless ($self->{status}) {	455	unless ($self->{_status}) {
283	push @{$self->{join}}, $current;	456	my $current = $current;
284	&schedule;	457
		458	push @{$self->{_on_destroy}}, sub {
		459	$current->ready;
		460	undef $current;
		461	};
		462
		463	&schedule while $current;
285	}	464	}
		465
286	wantarray ? @{$self->{status}} : $self->{status}[0];	466	wantarray ? @{$self->{_status}} : $self->{_status}[0];
287	}	467	}
288		468
		469	=item $coroutine->on_destroy (\&cb)
		470
		471	Registers a callback that is called when this coroutine gets destroyed,
		472	but before it is joined. The callback gets passed the terminate arguments,
		473	if any, and I<must not> die, under any circumstances.
		474
		475	=cut
		476
		477	sub on_destroy {
		478	my ($self, $cb) = @_;
		479
		480	push @{ $self->{_on_destroy} }, $cb;
		481	}
		482
289	=item $oldprio = $process->prio ($newprio)	483	=item $oldprio = $coroutine->prio ($newprio)
290		484
291	Sets (or gets, if the argument is missing) the priority of the	485	Sets (or gets, if the argument is missing) the priority of the
292	process. Higher priority processes get run before lower priority	486	coroutine. Higher priority coroutines get run before lower priority
293	processes. Priorities are small signed integers (currently -4 .. +3),	487	coroutines. Priorities are small signed integers (currently -4 .. +3),
294	that you can refer to using PRIO_xxx constants (use the import tag :prio	488	that you can refer to using PRIO_xxx constants (use the import tag :prio
295	to get then):	489	to get then):
296		490
297	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN	491	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
298	3 > 1 > 0 > -1 > -3 > -4	492	3 > 1 > 0 > -1 > -3 > -4
…		…
301	current->prio(PRIO_HIGH);	495	current->prio(PRIO_HIGH);
302		496
303	The idle coroutine ($Coro::idle) always has a lower priority than any	497	The idle coroutine ($Coro::idle) always has a lower priority than any
304	existing coroutine.	498	existing coroutine.
305		499
306	Changing the priority of the current process will take effect immediately,	500	Changing the priority of the current coroutine will take effect immediately,
307	but changing the priority of processes in the ready queue (but not	501	but changing the priority of coroutines in the ready queue (but not
308	running) will only take effect after the next schedule (of that	502	running) will only take effect after the next schedule (of that
309	process). This is a bug that will be fixed in some future version.	503	coroutine). This is a bug that will be fixed in some future version.
310		504
311	=item $newprio = $process->nice ($change)	505	=item $newprio = $coroutine->nice ($change)
312		506
313	Similar to C<prio>, but subtract the given value from the priority (i.e.	507	Similar to C<prio>, but subtract the given value from the priority (i.e.
314	higher values mean lower priority, just as in unix).	508	higher values mean lower priority, just as in unix).
315		509
316	=item $olddesc = $process->desc ($newdesc)	510	=item $olddesc = $coroutine->desc ($newdesc)
317		511
318	Sets (or gets in case the argument is missing) the description for this	512	Sets (or gets in case the argument is missing) the description for this
319	process. This is just a free-form string you can associate with a process.	513	coroutine. This is just a free-form string you can associate with a coroutine.
		514
		515	This method simply sets the C<< $coroutine->{desc} >> member to the given string. You
		516	can modify this member directly if you wish.
		517
		518	=item $coroutine->throw ([$scalar])
		519
		520	If C<$throw> is specified and defined, it will be thrown as an exception
		521	inside the coroutine at the next convinient point in time (usually after
		522	it gains control at the next schedule/transfer/cede). Otherwise clears the
		523	exception object.
		524
		525	The exception object will be thrown "as is" with the specified scalar in
		526	C<$@>, i.e. if it is a string, no line number or newline will be appended
		527	(unlike with C<die>).
		528
		529	This can be used as a softer means than C<cancel> to ask a coroutine to
		530	end itself, although there is no guarentee that the exception will lead to
		531	termination, and if the exception isn't caught it might well end the whole
		532	program.
320		533
321	=cut	534	=cut
322		535
323	sub desc {	536	sub desc {
324	my $old = $_[0]{desc};	537	my $old = $_[0]{desc};
…		…
326	$old;	539	$old;
327	}	540	}
328		541
329	=back	542	=back
330		543
		544	=head2 GLOBAL FUNCTIONS
		545
		546	=over 4
		547
		548	=item Coro::nready
		549
		550	Returns the number of coroutines that are currently in the ready state,
		551	i.e. that can be switched to by calling C<schedule> directory or
		552	indirectly. The value C<0> means that the only runnable coroutine is the
		553	currently running one, so C<cede> would have no effect, and C<schedule>
		554	would cause a deadlock unless there is an idle handler that wakes up some
		555	coroutines.
		556
		557	=item my $guard = Coro::guard { ... }
		558
		559	This creates and returns a guard object. Nothing happens until the object
		560	gets destroyed, in which case the codeblock given as argument will be
		561	executed. This is useful to free locks or other resources in case of a
		562	runtime error or when the coroutine gets canceled, as in both cases the
		563	guard block will be executed. The guard object supports only one method,
		564	C<< ->cancel >>, which will keep the codeblock from being executed.
		565
		566	Example: set some flag and clear it again when the coroutine gets canceled
		567	or the function returns:
		568
		569	sub do_something {
		570	my $guard = Coro::guard { $busy = 0 };
		571	$busy = 1;
		572
		573	# do something that requires $busy to be true
		574	}
		575
		576	=cut
		577
		578	sub guard(&) {
		579	bless \(my $cb = $_[0]), "Coro::guard"
		580	}
		581
		582	sub Coro::guard::cancel {
		583	${$_[0]} = sub { };
		584	}
		585
		586	sub Coro::guard::DESTROY {
		587	${$_[0]}->();
		588	}
		589
		590
		591	=item unblock_sub { ... }
		592
		593	This utility function takes a BLOCK or code reference and "unblocks" it,
		594	returning a new coderef. Unblocking means that calling the new coderef
		595	will return immediately without blocking, returning nothing, while the
		596	original code ref will be called (with parameters) from within another
		597	coroutine.
		598
		599	The reason this function exists is that many event libraries (such as the
		600	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		601	of thread-safety). This means you must not block within event callbacks,
		602	otherwise you might suffer from crashes or worse. The only event library
		603	currently known that is safe to use without C<unblock_sub> is L<EV>.
		604
		605	This function allows your callbacks to block by executing them in another
		606	coroutine where it is safe to block. One example where blocking is handy
		607	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		608	disk, for example.
		609
		610	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		611	creating event callbacks that want to block.
		612
		613	If your handler does not plan to block (e.g. simply sends a message to
		614	another coroutine, or puts some other coroutine into the ready queue),
		615	there is no reason to use C<unblock_sub>.
		616
		617	Note that you also need to use C<unblock_sub> for any other callbacks that
		618	are indirectly executed by any C-based event loop. For example, when you
		619	use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it
		620	provides callbacks that are the result of some event callback, then you
		621	must not block either, or use C<unblock_sub>.
		622
		623	=cut
		624
		625	our @unblock_queue;
		626
		627	# we create a special coro because we want to cede,
		628	# to reduce pressure on the coro pool (because most callbacks
		629	# return immediately and can be reused) and because we cannot cede
		630	# inside an event callback.
		631	our $unblock_scheduler = new Coro sub {
		632	while () {
		633	while (my $cb = pop @unblock_queue) {
		634	# this is an inlined copy of async_pool
		635	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		636
		637	$coro->{_invoke} = $cb;
		638	$coro->ready;
		639	cede; # for short-lived callbacks, this reduces pressure on the coro pool
		640	}
		641	schedule; # sleep well
		642	}
		643	};
		644	$unblock_scheduler->desc ("[unblock_sub scheduler]");
		645
		646	sub unblock_sub(&) {
		647	my $cb = shift;
		648
		649	sub {
		650	unshift @unblock_queue, [$cb, @_];
		651	$unblock_scheduler->ready;
		652	}
		653	}
		654
		655	=back
		656
331	=cut	657	=cut
332		658
333	1;	659	1;
334		660
335	=head1 BUGS/LIMITATIONS	661	=head1 BUGS/LIMITATIONS
336		662
337	- you must make very sure that no coro is still active on global
338	destruction. very bad things might happen otherwise (usually segfaults).
339
340	- this module is not thread-safe. You should only ever use this module	663	This module is not perl-pseudo-thread-safe. You should only ever use this
341	from the same thread (this requirement might be losened in the future	664	module from the same thread (this requirement might be removed in the
342	to allow per-thread schedulers, but Coro::State does not yet allow	665	future to allow per-thread schedulers, but Coro::State does not yet allow
343	this).	666	this). I recommend disabling thread support and using processes, as this
		667	is much faster and uses less memory.
344		668
345	=head1 SEE ALSO	669	=head1 SEE ALSO
346		670
		671	Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
		672
		673	Debugging: L<Coro::Debug>.
		674
347	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.	675	Support/Utility: L<Coro::Specific>, L<Coro::Util>.
348		676
349	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.	677	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
350		678
351	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.	679	IO/Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>.
352		680
353	Embedding: L<Coro:MakeMaker>	681	Compatibility: L<Coro::LWP>, L<Coro::BDB>, L<Coro::Storable>, L<Coro::Select>.
		682
		683	XS API: L<Coro::MakeMaker>.
		684
		685	Low level Configuration, Coroutine Environment: L<Coro::State>.
354		686
355	=head1 AUTHOR	687	=head1 AUTHOR
356		688
357	Marc Lehmann <schmorp@schmorp.de>	689	Marc Lehmann <schmorp@schmorp.de>
358	http://home.schmorp.de/	690	http://home.schmorp.de/

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Comparing Coro/Coro.pm (file contents): Revision 1.89 by root, Mon Nov 27 02:01:33 2006 UTC vs. Revision 1.186 by root, Sun May 25 01:32:36 2008 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.89 by root, Mon Nov 27 02:01:33 2006 UTC vs.
Revision 1.186 by root, Sun May 25 01:32:36 2008 UTC