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

Comparing Coro/Coro.pm (file contents):
Revision 1.65 by root, Tue Feb 22 19:51:58 2005 UTC vs.
Revision 1.181 by root, Fri May 9 22:04:37 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, such as multiple HTTP-GET requests
		41	running concurrently.
		42
		43	Coroutines are also useful because Perl has no support for threads (the so
		44	called "threads" that perl offers are nothing more than the (bad) process
		45	emulation coming from the Windows platform: On standard operating systems
		46	they serve no purpose whatsoever, except by making your programs slow and
		47	making them use a lot of memory. Best disable them when building perl, or
		48	aks your software vendor/distributor to do it for you).
		49
26	In this module, coroutines are defined as "callchain + lexical variables	50	In this module, coroutines are defined as "callchain + lexical variables +
27	+ @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own	51	@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,
28	callchain, it's own set of lexicals and it's own set of perl's most	52	its own set of lexicals and its own set of perls most important global
29	important global variables.	53	variables (see L<Coro::State> for more configuration).
30		54
31	=cut	55	=cut
32		56
33	package Coro;	57	package Coro;
34		58
35	BEGIN { eval { require warnings } && warnings->unimport ("uninitialized") }	59	use strict;
		60	no warnings "uninitialized";
36		61
37	use Coro::State;	62	use Coro::State;
38		63
39	use vars qw($idle $main $current);	64	use base qw(Coro::State Exporter);
40		65
41	use base Exporter;	66	our $idle; # idle handler
		67	our $main; # main coroutine
		68	our $current; # current coroutine
42		69
43	$VERSION = 1.1;	70	our $VERSION = 4.6;
44		71
45	@EXPORT = qw(async cede schedule terminate current);	72	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
46	%EXPORT_TAGS = (	73	our %EXPORT_TAGS = (
47	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	74	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
48	);	75	);
49	@EXPORT_OK = @{$EXPORT_TAGS{prio}};	76	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
50
51	{
52	my @async;
53	my $init;
54
55	# this way of handling attributes simply is NOT scalable ;()
56	sub import {
57	Coro->export_to_level(1, @_);
58	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
59	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
60	my ($package, $ref) = (shift, shift);
61	my @attrs;
62	for (@_) {
63	if ($_ eq "Coro") {
64	push @async, $ref;
65	unless ($init++) {
66	eval q{
67	sub INIT {
68	&async(pop @async) while @async;
69	}
70	};
71	}
72	} else {
73	push @attrs, $_;
74	}
75	}
76	return $old ? $old->($package, $ref, @attrs) : @attrs;
77	};
78	}
79
80	}
81		77
82	=over 4	78	=over 4
83		79
84	=item $main	80	=item $Coro::main
85		81
86	This coroutine represents the main program.	82	This variable stores the coroutine object that represents the main
		83	program. While you cna C<ready> it and do most other things you can do to
		84	coroutines, it is mainly useful to compare again C<$Coro::current>, to see
		85	wether you are running in the main program or not.
87		86
88	=cut	87	=cut
89		88
90	$main = new Coro;	89	$main = new Coro;
91		90
92	=item $current (or as function: current)	91	=item $Coro::current
93		92
94	The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).	93	The coroutine object representing the current coroutine (the last
		94	coroutine that the Coro scheduler switched to). The initial value is
		95	C<$main> (of course).
95		96
		97	This variable is B<strictly> I<read-only>. You can take copies of the
		98	value stored in it and use it as any other coroutine object, but you must
		99	not otherwise modify the variable itself.
		100
96	=cut	101	=cut
		102
		103	$main->{desc} = "[main::]";
97		104
98	# maybe some other module used Coro::Specific before...	105	# maybe some other module used Coro::Specific before...
99	if ($current) {
100	$main->{specific} = $current->{specific};	106	$main->{_specific} = $current->{_specific}
101	}	107	if $current;
102		108
103	$current = $main;	109	_set_current $main;
104		110
105	sub current() { $current }	111	sub current() { $current } # [DEPRECATED]
106		112
107	=item $idle	113	=item $Coro::idle
108		114
109	The coroutine to switch to when no other coroutine is running. The default	115	This variable is mainly useful to integrate Coro into event loops. It is
110	implementation prints "FATAL: deadlock detected" and exits.	116	usually better to rely on L<Coro::AnyEvent> or LC<Coro::EV>, as this is
		117	pretty low-level functionality.
111		118
112	=cut	119	This variable stores a callback that is called whenever the scheduler
		120	finds no ready coroutines to run. The default implementation prints
		121	"FATAL: deadlock detected" and exits, because the program has no other way
		122	to continue.
113		123
114	# should be done using priorities :(	124	This hook is overwritten by modules such as C<Coro::Timer> and
115	$idle = new Coro sub {	125	C<Coro::AnyEvent> to wait on an external event that hopefully wake up a
116	print STDERR "FATAL: deadlock detected\n";	126	coroutine so the scheduler can run it.
117	exit(51);	127
		128	Note that the callback I<must not>, under any circumstances, block
		129	the current coroutine. Normally, this is achieved by having an "idle
		130	coroutine" that calls the event loop and then blocks again, and then
		131	readying that coroutine in the idle handler.
		132
		133	See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this
		134	technique.
		135
		136	Please note that if your callback recursively invokes perl (e.g. for event
		137	handlers), then it must be prepared to be called recursively itself.
		138
		139	=cut
		140
		141	$idle = sub {
		142	require Carp;
		143	Carp::croak ("FATAL: deadlock detected");
118	};	144	};
		145
		146	sub _cancel {
		147	my ($self) = @_;
		148
		149	# free coroutine data and mark as destructed
		150	$self->_destroy
		151	or return;
		152
		153	# call all destruction callbacks
		154	$_->(@{$self->{_status}})
		155	for @{(delete $self->{_on_destroy}) \|\| []};
		156	}
119		157
120	# this coroutine is necessary because a coroutine	158	# this coroutine is necessary because a coroutine
121	# cannot destroy itself.	159	# cannot destroy itself.
122	my @destroy;	160	my @destroy;
123	my $manager;	161	my $manager;
		162
124	$manager = new Coro sub {	163	$manager = new Coro sub {
125	while () {	164	while () {
126	# by overwriting the state object with the manager we destroy it	165	(shift @destroy)->_cancel
127	# while still being able to schedule this coroutine (in case it has
128	# been readied multiple times. this is harmless since the manager
129	# can be called as many times as neccessary and will always
130	# remove itself from the runqueue
131	while (@destroy) {	166	while @destroy;
132	my $coro = pop @destroy;
133	$coro->{status} \|\|= [];
134	$_->ready for @{delete $coro->{join} \|\| []};
135		167
136	# the next line destroys the _coro_state, but keeps the
137	# process itself intact (we basically make it a zombie
138	# process that always runs the manager thread, so it's possible
139	# to transfer() to this process).
140	$coro->{_coro_state} = $manager->{_coro_state};
141	}
142	&schedule;	168	&schedule;
143	}	169	}
144	};	170	};
145		171	$manager->desc ("[coro manager]");
146	# static methods. not really.	172	$manager->prio (PRIO_MAX);
147		173
148	=back	174	=back
149		175
150	=head2 STATIC METHODS	176	=head2 SIMPLE COROUTINE CREATION
151
152	Static methods are actually functions that operate on the current process only.
153		177
154	=over 4	178	=over 4
155		179
156	=item async { ... } [@args...]	180	=item async { ... } [@args...]
157		181
158	Create a new asynchronous process and return it's process object	182	Create a new coroutine and return it's coroutine object (usually
159	(usually unused). When the sub returns the new process is automatically	183	unused). The coroutine will be put into the ready queue, so
		184	it will start running automatically on the next scheduler run.
		185
		186	The first argument is a codeblock/closure that should be executed in the
		187	coroutine. When it returns argument returns the coroutine is automatically
160	terminated.	188	terminated.
161		189
		190	The remaining arguments are passed as arguments to the closure.
		191
		192	See the C<Coro::State::new> constructor for info about the coroutine
		193	environment in which coroutines are executed.
		194
		195	Calling C<exit> in a coroutine will do the same as calling exit outside
		196	the coroutine. Likewise, when the coroutine dies, the program will exit,
		197	just as it would in the main program.
		198
		199	If you do not want that, you can provide a default C<die> handler, or
		200	simply avoid dieing (by use of C<eval>).
		201
162	# create a new coroutine that just prints its arguments	202	Example: Create a new coroutine that just prints its arguments.
		203
163	async {	204	async {
164	print "@_\n";	205	print "@_\n";
165	} 1,2,3,4;	206	} 1,2,3,4;
166		207
167	=cut	208	=cut
168		209
169	sub async(&@) {	210	sub async(&@) {
170	my $pid = new Coro @_;	211	my $coro = new Coro @_;
171	$manager->ready; # this ensures that the stack is cloned from the manager
172	$pid->ready;	212	$coro->ready;
173	$pid;	213	$coro
174	}	214	}
		215
		216	=item async_pool { ... } [@args...]
		217
		218	Similar to C<async>, but uses a coroutine pool, so you should not call
		219	terminate or join on it (although you are allowed to), and you get a
		220	coroutine that might have executed other code already (which can be good
		221	or bad :).
		222
		223	On the plus side, this function is faster than creating (and destroying)
		224	a completely new coroutine, so if you need a lot of generic coroutines in
		225	quick successsion, use C<async_pool>, not C<async>.
		226
		227	The code block is executed in an C<eval> context and a warning will be
		228	issued in case of an exception instead of terminating the program, as
		229	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
		230	will not work in the expected way, unless you call terminate or cancel,
		231	which somehow defeats the purpose of pooling (but is fine in the
		232	exceptional case).
		233
		234	The priority will be reset to C<0> after each run, tracing will be
		235	disabled, the description will be reset and the default output filehandle
		236	gets restored, so you can change all these. Otherwise the coroutine will
		237	be re-used "as-is": most notably if you change other per-coroutine global
		238	stuff such as C<$/> you I<must needs> to revert that change, which is most
		239	simply done by using local as in: C< local $/ >.
		240
		241	The pool size is limited to C<8> idle coroutines (this can be adjusted by
		242	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
		243	required.
		244
		245	If you are concerned about pooled coroutines growing a lot because a
		246	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
		247	{ terminate }> once per second or so to slowly replenish the pool. In
		248	addition to that, when the stacks used by a handler grows larger than 16kb
		249	(adjustable via $Coro::POOL_RSS) it will also be destroyed.
		250
		251	=cut
		252
		253	our $POOL_SIZE = 8;
		254	our $POOL_RSS = 16 * 1024;
		255	our @async_pool;
		256
		257	sub pool_handler {
		258	my $cb;
		259
		260	while () {
		261	eval {
		262	while () {
		263	_pool_1 $cb;
		264	&$cb;
		265	_pool_2 $cb;
		266	&schedule;
		267	}
		268	};
		269
		270	last if $@ eq "\3async_pool terminate\2\n";
		271	warn $@ if $@;
		272	}
		273	}
		274
		275	sub async_pool(&@) {
		276	# this is also inlined into the unlock_scheduler
		277	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		278
		279	$coro->{_invoke} = [@_];
		280	$coro->ready;
		281
		282	$coro
		283	}
		284
		285	=back
		286
		287	=head2 STATIC METHODS
		288
		289	Static methods are actually functions that operate on the current coroutine.
		290
		291	=over 4
175		292
176	=item schedule	293	=item schedule
177		294
178	Calls the scheduler. Please note that the current process will not be put	295	Calls the scheduler. The scheduler will find the next coroutine that is
		296	to be run from the ready queue and switches to it. The next coroutine
		297	to be run is simply the one with the highest priority that is longest
		298	in its ready queue. If there is no coroutine ready, it will clal the
		299	C<$Coro::idle> hook.
		300
		301	Please note that the current coroutine will I<not> be put into the ready
179	into the ready queue, so calling this function usually means you will	302	queue, so calling this function usually means you will never be called
180	never be called again.	303	again unless something else (e.g. an event handler) calls C<< ->ready >>,
		304	thus waking you up.
181		305
182	=cut	306	This makes C<schedule> I<the> generic method to use to block the current
		307	coroutine and wait for events: first you remember the current coroutine in
		308	a variable, then arrange for some callback of yours to call C<< ->ready
		309	>> on that once some event happens, and last you call C<schedule> to put
		310	yourself to sleep. Note that a lot of things can wake your coroutine up,
		311	so you need to check wether the event indeed happened, e.g. by storing the
		312	status in a variable.
		313
		314	The canonical way to wait on external events is this:
		315
		316	{
		317	# remember current coroutine
		318	my $current = $Coro::current;
		319
		320	# register a hypothetical event handler
		321	on_event_invoke sub {
		322	# wake up sleeping coroutine
		323	$current->ready;
		324	undef $current;
		325	};
		326
		327	# call schedule until event occurred.
		328	# in case we are woken up for other reasons
		329	# (current still defined), loop.
		330	Coro::schedule while $current;
		331	}
183		332
184	=item cede	333	=item cede
185		334
186	"Cede" to other processes. This function puts the current process into the	335	"Cede" to other coroutines. This function puts the current coroutine into
187	ready queue and calls C<schedule>, which has the effect of giving up the	336	the ready queue and calls C<schedule>, which has the effect of giving
188	current "timeslice" to other coroutines of the same or higher priority.	337	up the current "timeslice" to other coroutines of the same or higher
		338	priority. Once your coroutine gets its turn again it will automatically be
		339	resumed.
189		340
190	=cut	341	This function is often called C<yield> in other languages.
		342
		343	=item Coro::cede_notself
		344
		345	Works like cede, but is not exported by default and will cede to I<any>
		346	coroutine, regardless of priority. This is useful sometimes to ensure
		347	progress is made.
191		348
192	=item terminate [arg...]	349	=item terminate [arg...]
193		350
194	Terminates the current process with the given status values (see L<cancel>).	351	Terminates the current coroutine with the given status values (see L<cancel>).
		352
		353	=item killall
		354
		355	Kills/terminates/cancels all coroutines except the currently running
		356	one. This is useful after a fork, either in the child or the parent, as
		357	usually only one of them should inherit the running coroutines.
		358
		359	Note that while this will try to free some of the main programs resources,
		360	you cnanot free all of them, so if a coroutine that is not the main
		361	program calls this function, there will be some one-time resource leak.
195		362
196	=cut	363	=cut
197		364
198	sub terminate {	365	sub terminate {
199	$current->cancel (@_);	366	$current->cancel (@_);
200	}	367	}
201		368
		369	sub killall {
		370	for (Coro::State::list) {
		371	$_->cancel
		372	if $_ != $current && UNIVERSAL::isa $_, "Coro";
		373	}
		374	}
		375
202	=back	376	=back
203		377
204	# dynamic methods
205
206	=head2 PROCESS METHODS	378	=head2 COROUTINE METHODS
207		379
208	These are the methods you can call on process objects.	380	These are the methods you can call on coroutine objects (or to create
		381	them).
209		382
210	=over 4	383	=over 4
211		384
212	=item new Coro \&sub [, @args...]	385	=item new Coro \&sub [, @args...]
213		386
214	Create a new process and return it. When the sub returns the process	387	Create a new coroutine and return it. When the sub returns, the coroutine
215	automatically terminates as if C<terminate> with the returned values were	388	automatically terminates as if C<terminate> with the returned values were
216	called. To make the process run you must first put it into the ready queue	389	called. To make the coroutine run you must first put it into the ready
217	by calling the ready method.	390	queue by calling the ready method.
218		391
219	=cut	392	See C<async> and C<Coro::State::new> for additional info about the
		393	coroutine environment.
220		394
		395	=cut
		396
221	sub _newcoro {	397	sub _run_coro {
222	terminate &{+shift};	398	terminate &{+shift};
223	}	399	}
224		400
225	sub new {	401	sub new {
226	my $class = shift;	402	my $class = shift;
227	bless {
228	_coro_state => (new Coro::State $_[0] && \&_newcoro, @_),
229	}, $class;
230	}
231		403
232	=item $process->ready	404	$class->SUPER::new (\&_run_coro, @_)
		405	}
233		406
234	Put the given process into the ready queue.	407	=item $success = $coroutine->ready
235		408
236	=cut	409	Put the given coroutine into the end of its ready queue (there is one
		410	queue for each priority) and return true. If the coroutine is already in
		411	the ready queue, do nothing and return false.
237		412
		413	This ensures that the scheduler will resume this coroutine automatically
		414	once all the coroutines of higher priority and all coroutines of the same
		415	priority that were put into the ready queue earlier have been resumed.
		416
		417	=item $is_ready = $coroutine->is_ready
		418
		419	Return wether the coroutine is currently the ready queue or not,
		420
238	=item $process->cancel (arg...)	421	=item $coroutine->cancel (arg...)
239		422
240	Temrinates the given process and makes it return the given arguments as	423	Terminates the given coroutine and makes it return the given arguments as
241	status (default: the empty list).	424	status (default: the empty list). Never returns if the coroutine is the
		425	current coroutine.
242		426
243	=cut	427	=cut
244		428
245	sub cancel {	429	sub cancel {
246	my $self = shift;	430	my $self = shift;
247	$self->{status} = [@_];	431	$self->{_status} = [@_];
		432
		433	if ($current == $self) {
248	push @destroy, $self;	434	push @destroy, $self;
249	$manager->ready;	435	$manager->ready;
250	&schedule if $current == $self;	436	&schedule while 1;
		437	} else {
		438	$self->_cancel;
		439	}
251	}	440	}
252		441
253	=item $process->join	442	=item $coroutine->join
254		443
255	Wait until the coroutine terminates and return any values given to the	444	Wait until the coroutine terminates and return any values given to the
256	C<terminate> or C<cancel> functions. C<join> can be called multiple times	445	C<terminate> or C<cancel> functions. C<join> can be called concurrently
257	from multiple processes.	446	from multiple coroutines, and all will be resumed and given the status
		447	return once the C<$coroutine> terminates.
258		448
259	=cut	449	=cut
260		450
261	sub join {	451	sub join {
262	my $self = shift;	452	my $self = shift;
		453
263	unless ($self->{status}) {	454	unless ($self->{_status}) {
264	push @{$self->{join}}, $current;	455	my $current = $current;
265	&schedule;	456
		457	push @{$self->{_on_destroy}}, sub {
		458	$current->ready;
		459	undef $current;
		460	};
		461
		462	&schedule while $current;
266	}	463	}
		464
267	wantarray ? @{$self->{status}} : $self->{status}[0];	465	wantarray ? @{$self->{_status}} : $self->{_status}[0];
268	}	466	}
269		467
		468	=item $coroutine->on_destroy (\&cb)
		469
		470	Registers a callback that is called when this coroutine gets destroyed,
		471	but before it is joined. The callback gets passed the terminate arguments,
		472	if any, and I<must not> die, under any circumstances.
		473
		474	=cut
		475
		476	sub on_destroy {
		477	my ($self, $cb) = @_;
		478
		479	push @{ $self->{_on_destroy} }, $cb;
		480	}
		481
270	=item $oldprio = $process->prio($newprio)	482	=item $oldprio = $coroutine->prio ($newprio)
271		483
272	Sets (or gets, if the argument is missing) the priority of the	484	Sets (or gets, if the argument is missing) the priority of the
273	process. Higher priority processes get run before lower priority	485	coroutine. Higher priority coroutines get run before lower priority
274	processes. Priorities are small signed integers (currently -4 .. +3),	486	coroutines. Priorities are small signed integers (currently -4 .. +3),
275	that you can refer to using PRIO_xxx constants (use the import tag :prio	487	that you can refer to using PRIO_xxx constants (use the import tag :prio
276	to get then):	488	to get then):
277		489
278	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN	490	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
279	3 > 1 > 0 > -1 > -3 > -4	491	3 > 1 > 0 > -1 > -3 > -4
…		…
282	current->prio(PRIO_HIGH);	494	current->prio(PRIO_HIGH);
283		495
284	The idle coroutine ($Coro::idle) always has a lower priority than any	496	The idle coroutine ($Coro::idle) always has a lower priority than any
285	existing coroutine.	497	existing coroutine.
286		498
287	Changing the priority of the current process will take effect immediately,	499	Changing the priority of the current coroutine will take effect immediately,
288	but changing the priority of processes in the ready queue (but not	500	but changing the priority of coroutines in the ready queue (but not
289	running) will only take effect after the next schedule (of that	501	running) will only take effect after the next schedule (of that
290	process). This is a bug that will be fixed in some future version.	502	coroutine). This is a bug that will be fixed in some future version.
291		503
292	=cut
293
294	sub prio {
295	my $old = $_[0]{prio};
296	$_[0]{prio} = $_[1] if @_ > 1;
297	$old;
298	}
299
300	=item $newprio = $process->nice($change)	504	=item $newprio = $coroutine->nice ($change)
301		505
302	Similar to C<prio>, but subtract the given value from the priority (i.e.	506	Similar to C<prio>, but subtract the given value from the priority (i.e.
303	higher values mean lower priority, just as in unix).	507	higher values mean lower priority, just as in unix).
304		508
305	=cut
306
307	sub nice {
308	$_[0]{prio} -= $_[1];
309	}
310
311	=item $olddesc = $process->desc($newdesc)	509	=item $olddesc = $coroutine->desc ($newdesc)
312		510
313	Sets (or gets in case the argument is missing) the description for this	511	Sets (or gets in case the argument is missing) the description for this
314	process. This is just a free-form string you can associate with a process.	512	coroutine. This is just a free-form string you can associate with a coroutine.
		513
		514	This method simply sets the C<< $coroutine->{desc} >> member to the given string. You
		515	can modify this member directly if you wish.
		516
		517	=item $coroutine->throw ([$scalar])
		518
		519	If C<$throw> is specified and defined, it will be thrown as an exception
		520	inside the coroutine at the next convinient point in time (usually after
		521	it gains control at the next schedule/transfer/cede). Otherwise clears the
		522	exception object.
		523
		524	The exception object will be thrown "as is" with the specified scalar in
		525	C<$@>, i.e. if it is a string, no line number or newline will be appended
		526	(unlike with C<die>).
		527
		528	This can be used as a softer means than C<cancel> to ask a coroutine to
		529	end itself, although there is no guarentee that the exception will lead to
		530	termination, and if the exception isn't caught it might well end the whole
		531	program.
315		532
316	=cut	533	=cut
317		534
318	sub desc {	535	sub desc {
319	my $old = $_[0]{desc};	536	my $old = $_[0]{desc};
…		…
321	$old;	538	$old;
322	}	539	}
323		540
324	=back	541	=back
325		542
		543	=head2 GLOBAL FUNCTIONS
		544
		545	=over 4
		546
		547	=item Coro::nready
		548
		549	Returns the number of coroutines that are currently in the ready state,
		550	i.e. that can be switched to by calling C<schedule> directory or
		551	indirectly. The value C<0> means that the only runnable coroutine is the
		552	currently running one, so C<cede> would have no effect, and C<schedule>
		553	would cause a deadlock unless there is an idle handler that wakes up some
		554	coroutines.
		555
		556	=item my $guard = Coro::guard { ... }
		557
		558	This creates and returns a guard object. Nothing happens until the object
		559	gets destroyed, in which case the codeblock given as argument will be
		560	executed. This is useful to free locks or other resources in case of a
		561	runtime error or when the coroutine gets canceled, as in both cases the
		562	guard block will be executed. The guard object supports only one method,
		563	C<< ->cancel >>, which will keep the codeblock from being executed.
		564
		565	Example: set some flag and clear it again when the coroutine gets canceled
		566	or the function returns:
		567
		568	sub do_something {
		569	my $guard = Coro::guard { $busy = 0 };
		570	$busy = 1;
		571
		572	# do something that requires $busy to be true
		573	}
		574
		575	=cut
		576
		577	sub guard(&) {
		578	bless \(my $cb = $_[0]), "Coro::guard"
		579	}
		580
		581	sub Coro::guard::cancel {
		582	${$_[0]} = sub { };
		583	}
		584
		585	sub Coro::guard::DESTROY {
		586	${$_[0]}->();
		587	}
		588
		589
		590	=item unblock_sub { ... }
		591
		592	This utility function takes a BLOCK or code reference and "unblocks" it,
		593	returning a new coderef. Unblocking means that calling the new coderef
		594	will return immediately without blocking, returning nothing, while the
		595	original code ref will be called (with parameters) from within another
		596	coroutine.
		597
		598	The reason this function exists is that many event libraries (such as the
		599	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		600	of thread-safety). This means you must not block within event callbacks,
		601	otherwise you might suffer from crashes or worse. The only event library
		602	currently known that is safe to use without C<unblock_sub> is L<EV>.
		603
		604	This function allows your callbacks to block by executing them in another
		605	coroutine where it is safe to block. One example where blocking is handy
		606	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		607	disk, for example.
		608
		609	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		610	creating event callbacks that want to block.
		611
		612	If your handler does not plan to block (e.g. simply sends a message to
		613	another coroutine, or puts some other coroutine into the ready queue),
		614	there is no reason to use C<unblock_sub>.
		615
		616	=cut
		617
		618	our @unblock_queue;
		619
		620	# we create a special coro because we want to cede,
		621	# to reduce pressure on the coro pool (because most callbacks
		622	# return immediately and can be reused) and because we cannot cede
		623	# inside an event callback.
		624	our $unblock_scheduler = new Coro sub {
		625	while () {
		626	while (my $cb = pop @unblock_queue) {
		627	# this is an inlined copy of async_pool
		628	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
		629
		630	$coro->{_invoke} = $cb;
		631	$coro->ready;
		632	cede; # for short-lived callbacks, this reduces pressure on the coro pool
		633	}
		634	schedule; # sleep well
		635	}
		636	};
		637	$unblock_scheduler->desc ("[unblock_sub scheduler]");
		638
		639	sub unblock_sub(&) {
		640	my $cb = shift;
		641
		642	sub {
		643	unshift @unblock_queue, [$cb, @_];
		644	$unblock_scheduler->ready;
		645	}
		646	}
		647
		648	=back
		649
326	=cut	650	=cut
327		651
328	1;	652	1;
329		653
330	=head1 BUGS/LIMITATIONS	654	=head1 BUGS/LIMITATIONS
331		655
332	- you must make very sure that no coro is still active on global
333	destruction. very bad things might happen otherwise (usually segfaults).
334
335	- this module is not thread-safe. You should only ever use this module	656	This module is not perl-pseudo-thread-safe. You should only ever use this
336	from the same thread (this requirement might be losened in the future	657	module from the same thread (this requirement might be removed in the
337	to allow per-thread schedulers, but Coro::State does not yet allow	658	future to allow per-thread schedulers, but Coro::State does not yet allow
338	this).	659	this). I recommend disabling thread support and using processes, as this
		660	is much faster and uses less memory.
339		661
340	=head1 SEE ALSO	662	=head1 SEE ALSO
341		663
342	L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,	664	Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
343	L<Coro::Signal>, L<Coro::State>, L<Coro::Timer>, L<Coro::Event>,	665
344	L<Coro::Handle>, L<Coro::RWLock>, L<Coro::Socket>.	666	Debugging: L<Coro::Debug>.
		667
		668	Support/Utility: L<Coro::Specific>, L<Coro::Util>.
		669
		670	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
		671
		672	IO/Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>.
		673
		674	Compatibility: L<Coro::LWP>, L<Coro::BDB>, L<Coro::Storable>, L<Coro::Select>.
		675
		676	XS API: L<Coro::MakeMaker>.
		677
		678	Low level Configuration, Coroutine Environment: L<Coro::State>.
345		679
346	=head1 AUTHOR	680	=head1 AUTHOR
347		681
348	Marc Lehmann <pcg@goof.com>	682	Marc Lehmann <schmorp@schmorp.de>
349	http://home.schmorp.de/	683	http://home.schmorp.de/
350		684
351	=cut	685	=cut
352		686

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Revision 1.181 by root, Fri May 9 22:04:37 2008 UTC