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

Comparing Coro/Coro.pm (file contents):
Revision 1.66 by root, Thu Mar 3 17:20:31 2005 UTC vs.
Revision 1.249 by root, Mon Dec 15 15:21:25 2008 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	Coro - coroutine process abstraction	3	Coro - the only real threads in perl
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 coro
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	use Coro::Semaphore;
19	cede;	22	my $lock = new Coro::Semaphore;
		23	my $locked;
		24
		25	$lock->down;
		26	$locked = 1;
		27	$lock->up;
20		28
21	=head1 DESCRIPTION	29	=head1 DESCRIPTION
22		30
23	This module collection manages coroutines. Coroutines are similar to	31	For a tutorial-style introduction, please read the L<Coro::Intro>
24	threads but don't run in parallel.	32	manpage. This manpage mainly contains reference information.
25		33
		34	This module collection manages continuations in general, most often in
		35	the form of cooperative threads (also called coros, or simply "coro"
		36	in the documentation). They are similar to kernel threads but don't (in
		37	general) run in parallel at the same time even on SMP machines. The
		38	specific flavor of thread offered by this module also guarantees you that
		39	it will not switch between threads unless necessary, at easily-identified
		40	points in your program, so locking and parallel access are rarely an
		41	issue, making thread programming much safer and easier than using other
		42	thread models.
		43
		44	Unlike the so-called "Perl threads" (which are not actually real threads
		45	but only the windows process emulation ported to unix, and as such act
		46	as processes), Coro provides a full shared address space, which makes
		47	communication between threads very easy. And Coro's threads are fast,
		48	too: disabling the Windows process emulation code in your perl and using
		49	Coro can easily result in a two to four times speed increase for your
		50	programs. A parallel matrix multiplication benchmark runs over 300 times
		51	faster on a single core than perl's pseudo-threads on a quad core using
		52	all four cores.
		53
		54	Coro achieves that by supporting multiple running interpreters that share
		55	data, which is especially useful to code pseudo-parallel processes and
		56	for event-based programming, such as multiple HTTP-GET requests running
		57	concurrently. See L<Coro::AnyEvent> to learn more on how to integrate Coro
		58	into an event-based environment.
		59
26	In this module, coroutines are defined as "callchain + lexical variables	60	In this module, a thread is defined as "callchain + lexical variables +
27	+ @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own	61	some package variables + C stack), that is, a thread has its own callchain,
28	callchain, it's own set of lexicals and it's own set of perl's most	62	its own set of lexicals and its own set of perls most important global
29	important global variables.	63	variables (see L<Coro::State> for more configuration and background info).
		64
		65	See also the C<SEE ALSO> section at the end of this document - the Coro
		66	module family is quite large.
30		67
31	=cut	68	=cut
32		69
33	package Coro;	70	package Coro;
34		71
35	BEGIN { eval { require warnings } && warnings->unimport ("uninitialized") }	72	use strict qw(vars subs);
		73	no warnings "uninitialized";
		74
		75	use Guard ();
36		76
37	use Coro::State;	77	use Coro::State;
38		78
39	use vars qw($idle $main $current);	79	use base qw(Coro::State Exporter);
40		80
41	use base Exporter;	81	our $idle; # idle handler
		82	our $main; # main coro
		83	our $current; # current coro
42		84
43	$VERSION = 1.11;	85	our $VERSION = 5.13;
44		86
45	@EXPORT = qw(async cede schedule terminate current);	87	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
46	%EXPORT_TAGS = (	88	our %EXPORT_TAGS = (
47	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	89	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
48	);	90	);
49	@EXPORT_OK = @{$EXPORT_TAGS{prio}};	91	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
50		92
51	{	93	=head1 GLOBAL VARIABLES
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		94
82	=over 4	95	=over 4
83		96
84	=item $main	97	=item $Coro::main
85		98
86	This coroutine represents the main program.	99	This variable stores the Coro object that represents the main
		100	program. While you cna C<ready> it and do most other things you can do to
		101	coro, it is mainly useful to compare again C<$Coro::current>, to see
		102	whether you are running in the main program or not.
87		103
88	=cut	104	=cut
89		105
90	$main = new Coro;	106	# $main is now being initialised by Coro::State
91		107
92	=item $current (or as function: current)	108	=item $Coro::current
93		109
94	The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).	110	The Coro object representing the current coro (the last
		111	coro that the Coro scheduler switched to). The initial value is
		112	C<$Coro::main> (of course).
95		113
96	=cut	114	This variable is B<strictly> I<read-only>. You can take copies of the
		115	value stored in it and use it as any other Coro object, but you must
		116	not otherwise modify the variable itself.
97		117
98	# maybe some other module used Coro::Specific before...	118	=cut
99	if ($current) {
100	$main->{specific} = $current->{specific};
101	}
102		119
103	$current = $main;
104
105	sub current() { $current }	120	sub current() { $current } # [DEPRECATED]
106		121
107	=item $idle	122	=item $Coro::idle
108		123
109	The coroutine to switch to when no other coroutine is running. The default	124	This variable is mainly useful to integrate Coro into event loops. It is
110	implementation prints "FATAL: deadlock detected" and exits.	125	usually better to rely on L<Coro::AnyEvent> or L<Coro::EV>, as this is
		126	pretty low-level functionality.
111		127
112	=cut	128	This variable stores either a Coro object or a callback.
113		129
114	# should be done using priorities :(	130	If it is a callback, the it is called whenever the scheduler finds no
115	$idle = new Coro sub {	131	ready coros to run. The default implementation prints "FATAL:
116	print STDERR "FATAL: deadlock detected\n";	132	deadlock detected" and exits, because the program has no other way to
117	exit(51);	133	continue.
		134
		135	If it is a coro object, then this object will be readied (without
		136	invoking any ready hooks, however) when the scheduler finds no other ready
		137	coros to run.
		138
		139	This hook is overwritten by modules such as C<Coro::EV> and
		140	C<Coro::AnyEvent> to wait on an external event that hopefully wake up a
		141	coro so the scheduler can run it.
		142
		143	Note that the callback I<must not>, under any circumstances, block
		144	the current coro. Normally, this is achieved by having an "idle
		145	coro" that calls the event loop and then blocks again, and then
		146	readying that coro in the idle handler, or by simply placing the idle
		147	coro in this variable.
		148
		149	See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this
		150	technique.
		151
		152	Please note that if your callback recursively invokes perl (e.g. for event
		153	handlers), then it must be prepared to be called recursively itself.
		154
		155	=cut
		156
		157	$idle = sub {
		158	require Carp;
		159	Carp::croak ("FATAL: deadlock detected");
118	};	160	};
119		161
120	# this coroutine is necessary because a coroutine	162	# this coro is necessary because a coro
121	# cannot destroy itself.	163	# cannot destroy itself.
122	my @destroy;	164	our @destroy;
123	my $manager;	165	our $manager;
		166
124	$manager = new Coro sub {	167	$manager = new Coro sub {
125	while () {	168	while () {
126	# by overwriting the state object with the manager we destroy it	169	Coro::State::cancel shift @destroy
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) {	170	while @destroy;
132	my $coro = pop @destroy;
133	$coro->{status} \|\|= [];
134	$_->ready for @{delete $coro->{join} \|\| []};
135		171
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;	172	&schedule;
143	}	173	}
144	};	174	};
145		175	$manager->{desc} = "[coro manager]";
146	# static methods. not really.	176	$manager->prio (PRIO_MAX);
147		177
148	=back	178	=back
149		179
150	=head2 STATIC METHODS	180	=head1 SIMPLE CORO CREATION
151
152	Static methods are actually functions that operate on the current process only.
153		181
154	=over 4	182	=over 4
155		183
156	=item async { ... } [@args...]	184	=item async { ... } [@args...]
157		185
158	Create a new asynchronous process and return it's process object	186	Create a new coro and return its Coro object (usually
159	(usually unused). When the sub returns the new process is automatically	187	unused). The coro will be put into the ready queue, so
		188	it will start running automatically on the next scheduler run.
		189
		190	The first argument is a codeblock/closure that should be executed in the
		191	coro. When it returns argument returns the coro is automatically
160	terminated.	192	terminated.
161		193
		194	The remaining arguments are passed as arguments to the closure.
		195
		196	See the C<Coro::State::new> constructor for info about the coro
		197	environment in which coro are executed.
		198
		199	Calling C<exit> in a coro will do the same as calling exit outside
		200	the coro. Likewise, when the coro dies, the program will exit,
		201	just as it would in the main program.
		202
		203	If you do not want that, you can provide a default C<die> handler, or
		204	simply avoid dieing (by use of C<eval>).
		205
162	# create a new coroutine that just prints its arguments	206	Example: Create a new coro that just prints its arguments.
		207
163	async {	208	async {
164	print "@_\n";	209	print "@_\n";
165	} 1,2,3,4;	210	} 1,2,3,4;
166		211
167	=cut	212	=cut
168		213
169	sub async(&@) {	214	sub async(&@) {
170	my $pid = new Coro @_;	215	my $coro = new Coro @_;
171	$manager->ready; # this ensures that the stack is cloned from the manager
172	$pid->ready;	216	$coro->ready;
173	$pid;	217	$coro
174	}	218	}
		219
		220	=item async_pool { ... } [@args...]
		221
		222	Similar to C<async>, but uses a coro pool, so you should not call
		223	terminate or join on it (although you are allowed to), and you get a
		224	coro that might have executed other code already (which can be good
		225	or bad :).
		226
		227	On the plus side, this function is about twice as fast as creating (and
		228	destroying) a completely new coro, so if you need a lot of generic
		229	coros in quick successsion, use C<async_pool>, not C<async>.
		230
		231	The code block is executed in an C<eval> context and a warning will be
		232	issued in case of an exception instead of terminating the program, as
		233	C<async> does. As the coro is being reused, stuff like C<on_destroy>
		234	will not work in the expected way, unless you call terminate or cancel,
		235	which somehow defeats the purpose of pooling (but is fine in the
		236	exceptional case).
		237
		238	The priority will be reset to C<0> after each run, tracing will be
		239	disabled, the description will be reset and the default output filehandle
		240	gets restored, so you can change all these. Otherwise the coro will
		241	be re-used "as-is": most notably if you change other per-coro global
		242	stuff such as C<$/> you I<must needs> revert that change, which is most
		243	simply done by using local as in: C<< local $/ >>.
		244
		245	The idle pool size is limited to C<8> idle coros (this can be
		246	adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle
		247	coros as required.
		248
		249	If you are concerned about pooled coros growing a lot because a
		250	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
		251	{ terminate }> once per second or so to slowly replenish the pool. In
		252	addition to that, when the stacks used by a handler grows larger than 32kb
		253	(adjustable via $Coro::POOL_RSS) it will also be destroyed.
		254
		255	=cut
		256
		257	our $POOL_SIZE = 8;
		258	our $POOL_RSS = 32 * 1024;
		259	our @async_pool;
		260
		261	sub pool_handler {
		262	while () {
		263	eval {
		264	&{&_pool_handler} while 1;
		265	};
		266
		267	warn $@ if $@;
		268	}
		269	}
		270
		271	=back
		272
		273	=head1 STATIC METHODS
		274
		275	Static methods are actually functions that implicitly operate on the
		276	current coro.
		277
		278	=over 4
175		279
176	=item schedule	280	=item schedule
177		281
178	Calls the scheduler. Please note that the current process will not be put	282	Calls the scheduler. The scheduler will find the next coro that is
		283	to be run from the ready queue and switches to it. The next coro
		284	to be run is simply the one with the highest priority that is longest
		285	in its ready queue. If there is no coro ready, it will clal the
		286	C<$Coro::idle> hook.
		287
		288	Please note that the current coro will I<not> be put into the ready
179	into the ready queue, so calling this function usually means you will	289	queue, so calling this function usually means you will never be called
180	never be called again.	290	again unless something else (e.g. an event handler) calls C<< ->ready >>,
		291	thus waking you up.
181		292
182	=cut	293	This makes C<schedule> I<the> generic method to use to block the current
		294	coro and wait for events: first you remember the current coro in
		295	a variable, then arrange for some callback of yours to call C<< ->ready
		296	>> on that once some event happens, and last you call C<schedule> to put
		297	yourself to sleep. Note that a lot of things can wake your coro up,
		298	so you need to check whether the event indeed happened, e.g. by storing the
		299	status in a variable.
		300
		301	See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks.
183		302
184	=item cede	303	=item cede
185		304
186	"Cede" to other processes. This function puts the current process into the	305	"Cede" to other coros. This function puts the current coro into
187	ready queue and calls C<schedule>, which has the effect of giving up the	306	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.	307	up the current "timeslice" to other coros of the same or higher
		308	priority. Once your coro gets its turn again it will automatically be
		309	resumed.
189		310
190	=cut	311	This function is often called C<yield> in other languages.
		312
		313	=item Coro::cede_notself
		314
		315	Works like cede, but is not exported by default and will cede to I<any>
		316	coro, regardless of priority. This is useful sometimes to ensure
		317	progress is made.
191		318
192	=item terminate [arg...]	319	=item terminate [arg...]
193		320
194	Terminates the current process with the given status values (see L<cancel>).	321	Terminates the current coro with the given status values (see L<cancel>).
195		322
196	=cut	323	=item Coro::on_enter BLOCK, Coro::on_leave BLOCK
197		324
198	sub terminate {	325	These function install enter and leave winders in the current scope. The
199	$current->cancel (@_);	326	enter block will be executed when on_enter is called and whenever the
		327	current coro is re-entered by the scheduler, while the leave block is
		328	executed whenever the current coro is blocked by the scheduler, and
		329	also when the containing scope is exited (by whatever means, be it exit,
		330	die, last etc.).
		331
		332	I<Neither invoking the scheduler, nor exceptions, are allowed within those
		333	BLOCKs>. That means: do not even think about calling C<die> without an
		334	eval, and do not even think of entering the scheduler in any way.
		335
		336	Since both BLOCKs are tied to the current scope, they will automatically
		337	be removed when the current scope exits.
		338
		339	These functions implement the same concept as C<dynamic-wind> in scheme
		340	does, and are useful when you want to localise some resource to a specific
		341	coro.
		342
		343	They slow down coro switching considerably for coros that use
		344	them (But coro switching is still reasonably fast if the handlers are
		345	fast).
		346
		347	These functions are best understood by an example: The following function
		348	will change the current timezone to "Antarctica/South_Pole", which
		349	requires a call to C<tzset>, but by using C<on_enter> and C<on_leave>,
		350	which remember/change the current timezone and restore the previous
		351	value, respectively, the timezone is only changes for the coro that
		352	installed those handlers.
		353
		354	use POSIX qw(tzset);
		355
		356	async {
		357	my $old_tz; # store outside TZ value here
		358
		359	Coro::on_enter {
		360	$old_tz = $ENV{TZ}; # remember the old value
		361
		362	$ENV{TZ} = "Antarctica/South_Pole";
		363	tzset; # enable new value
		364	};
		365
		366	Coro::on_leave {
		367	$ENV{TZ} = $old_tz;
		368	tzset; # restore old value
		369	};
		370
		371	# at this place, the timezone is Antarctica/South_Pole,
		372	# without disturbing the TZ of any other coro.
		373	};
		374
		375	This can be used to localise about any resource (locale, uid, current
		376	working directory etc.) to a block, despite the existance of other
		377	coros.
		378
		379	=item killall
		380
		381	Kills/terminates/cancels all coros except the currently running one.
		382
		383	Note that while this will try to free some of the main interpreter
		384	resources if the calling coro isn't the main coro, but one
		385	cannot free all of them, so if a coro that is not the main coro
		386	calls this function, there will be some one-time resource leak.
		387
		388	=cut
		389
		390	sub killall {
		391	for (Coro::State::list) {
		392	$_->cancel
		393	if $_ != $current && UNIVERSAL::isa $_, "Coro";
		394	}
200	}	395	}
201		396
202	=back	397	=back
203		398
204	# dynamic methods	399	=head1 CORO OBJECT METHODS
205		400
206	=head2 PROCESS METHODS
207
208	These are the methods you can call on process objects.	401	These are the methods you can call on coro objects (or to create
		402	them).
209		403
210	=over 4	404	=over 4
211		405
212	=item new Coro \&sub [, @args...]	406	=item new Coro \&sub [, @args...]
213		407
214	Create a new process and return it. When the sub returns the process	408	Create a new coro and return it. When the sub returns, the coro
215	automatically terminates as if C<terminate> with the returned values were	409	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	410	called. To make the coro run you must first put it into the ready
217	by calling the ready method.	411	queue by calling the ready method.
218		412
219	=cut	413	See C<async> and C<Coro::State::new> for additional info about the
		414	coro environment.
220		415
		416	=cut
		417
221	sub _newcoro {	418	sub _coro_run {
222	terminate &{+shift};	419	terminate &{+shift};
223	}	420	}
224		421
225	sub new {	422	=item $success = $coro->ready
226	my $class = shift;
227	bless {
228	_coro_state => (new Coro::State $_[0] && \&_newcoro, @_),
229	}, $class;
230	}
231		423
232	=item $process->ready	424	Put the given coro into the end of its ready queue (there is one
		425	queue for each priority) and return true. If the coro is already in
		426	the ready queue, do nothing and return false.
233		427
234	Put the given process into the ready queue.	428	This ensures that the scheduler will resume this coro automatically
		429	once all the coro of higher priority and all coro of the same
		430	priority that were put into the ready queue earlier have been resumed.
235		431
236	=cut	432	=item $is_ready = $coro->is_ready
237		433
		434	Returns true iff the Coro object is in the ready queue. Unless the Coro
		435	object gets destroyed, it will eventually be scheduled by the scheduler.
		436
		437	=item $is_running = $coro->is_running
		438
		439	Returns true iff the Coro object is currently running. Only one Coro object
		440	can ever be in the running state (but it currently is possible to have
		441	multiple running Coro::States).
		442
		443	=item $is_suspended = $coro->is_suspended
		444
		445	Returns true iff this Coro object has been suspended. Suspended Coros will
		446	not ever be scheduled.
		447
238	=item $process->cancel (arg...)	448	=item $coro->cancel (arg...)
239		449
240	Temrinates the given process and makes it return the given arguments as	450	Terminates the given Coro and makes it return the given arguments as
241	status (default: the empty list).	451	status (default: the empty list). Never returns if the Coro is the
		452	current Coro.
242		453
243	=cut	454	=cut
244		455
245	sub cancel {	456	sub cancel {
246	my $self = shift;	457	my $self = shift;
		458
		459	if ($current == $self) {
		460	terminate @_;
		461	} else {
247	$self->{status} = [@_];	462	$self->{_status} = [@_];
248	push @destroy, $self;	463	Coro::State::cancel $self;
249	$manager->ready;	464	}
250	&schedule if $current == $self;
251	}	465	}
252		466
		467	=item $coro->schedule_to
		468
		469	Puts the current coro to sleep (like C<Coro::schedule>), but instead
		470	of continuing with the next coro from the ready queue, always switch to
		471	the given coro object (regardless of priority etc.). The readyness
		472	state of that coro isn't changed.
		473
		474	This is an advanced method for special cases - I'd love to hear about any
		475	uses for this one.
		476
		477	=item $coro->cede_to
		478
		479	Like C<schedule_to>, but puts the current coro into the ready
		480	queue. This has the effect of temporarily switching to the given
		481	coro, and continuing some time later.
		482
		483	This is an advanced method for special cases - I'd love to hear about any
		484	uses for this one.
		485
		486	=item $coro->throw ([$scalar])
		487
		488	If C<$throw> is specified and defined, it will be thrown as an exception
		489	inside the coro at the next convenient point in time. Otherwise
		490	clears the exception object.
		491
		492	Coro will check for the exception each time a schedule-like-function
		493	returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down
		494	>>, C<< Coro::Handle->readable >> and so on. Most of these functions
		495	detect this case and return early in case an exception is pending.
		496
		497	The exception object will be thrown "as is" with the specified scalar in
		498	C<$@>, i.e. if it is a string, no line number or newline will be appended
		499	(unlike with C<die>).
		500
		501	This can be used as a softer means than C<cancel> to ask a coro to
		502	end itself, although there is no guarantee that the exception will lead to
		503	termination, and if the exception isn't caught it might well end the whole
		504	program.
		505
		506	You might also think of C<throw> as being the moral equivalent of
		507	C<kill>ing a coro with a signal (in this case, a scalar).
		508
253	=item $process->join	509	=item $coro->join
254		510
255	Wait until the coroutine terminates and return any values given to the	511	Wait until the coro terminates and return any values given to the
256	C<terminate> or C<cancel> functions. C<join> can be called multiple times	512	C<terminate> or C<cancel> functions. C<join> can be called concurrently
257	from multiple processes.	513	from multiple coro, and all will be resumed and given the status
		514	return once the C<$coro> terminates.
258		515
259	=cut	516	=cut
260		517
261	sub join {	518	sub join {
262	my $self = shift;	519	my $self = shift;
		520
263	unless ($self->{status}) {	521	unless ($self->{_status}) {
264	push @{$self->{join}}, $current;	522	my $current = $current;
265	&schedule;	523
		524	push @{$self->{_on_destroy}}, sub {
		525	$current->ready;
		526	undef $current;
		527	};
		528
		529	&schedule while $current;
266	}	530	}
		531
267	wantarray ? @{$self->{status}} : $self->{status}[0];	532	wantarray ? @{$self->{_status}} : $self->{_status}[0];
268	}	533	}
269		534
		535	=item $coro->on_destroy (\&cb)
		536
		537	Registers a callback that is called when this coro gets destroyed,
		538	but before it is joined. The callback gets passed the terminate arguments,
		539	if any, and I<must not> die, under any circumstances.
		540
		541	=cut
		542
		543	sub on_destroy {
		544	my ($self, $cb) = @_;
		545
		546	push @{ $self->{_on_destroy} }, $cb;
		547	}
		548
270	=item $oldprio = $process->prio($newprio)	549	=item $oldprio = $coro->prio ($newprio)
271		550
272	Sets (or gets, if the argument is missing) the priority of the	551	Sets (or gets, if the argument is missing) the priority of the
273	process. Higher priority processes get run before lower priority	552	coro. Higher priority coro get run before lower priority
274	processes. Priorities are small signed integers (currently -4 .. +3),	553	coro. Priorities are small signed integers (currently -4 .. +3),
275	that you can refer to using PRIO_xxx constants (use the import tag :prio	554	that you can refer to using PRIO_xxx constants (use the import tag :prio
276	to get then):	555	to get then):
277		556
278	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN	557	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
279	3 > 1 > 0 > -1 > -3 > -4	558	3 > 1 > 0 > -1 > -3 > -4
280		559
281	# set priority to HIGH	560	# set priority to HIGH
282	current->prio(PRIO_HIGH);	561	current->prio (PRIO_HIGH);
283		562
284	The idle coroutine ($Coro::idle) always has a lower priority than any	563	The idle coro ($Coro::idle) always has a lower priority than any
285	existing coroutine.	564	existing coro.
286		565
287	Changing the priority of the current process will take effect immediately,	566	Changing the priority of the current coro will take effect immediately,
288	but changing the priority of processes in the ready queue (but not	567	but changing the priority of coro in the ready queue (but not
289	running) will only take effect after the next schedule (of that	568	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.	569	coro). This is a bug that will be fixed in some future version.
291		570
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)	571	=item $newprio = $coro->nice ($change)
301		572
302	Similar to C<prio>, but subtract the given value from the priority (i.e.	573	Similar to C<prio>, but subtract the given value from the priority (i.e.
303	higher values mean lower priority, just as in unix).	574	higher values mean lower priority, just as in unix).
304		575
305	=cut
306
307	sub nice {
308	$_[0]{prio} -= $_[1];
309	}
310
311	=item $olddesc = $process->desc($newdesc)	576	=item $olddesc = $coro->desc ($newdesc)
312		577
313	Sets (or gets in case the argument is missing) the description for this	578	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.	579	coro. This is just a free-form string you can associate with a
		580	coro.
		581
		582	This method simply sets the C<< $coro->{desc} >> member to the given
		583	string. You can modify this member directly if you wish.
315		584
316	=cut	585	=cut
317		586
318	sub desc {	587	sub desc {
319	my $old = $_[0]{desc};	588	my $old = $_[0]{desc};
320	$_[0]{desc} = $_[1] if @_ > 1;	589	$_[0]{desc} = $_[1] if @_ > 1;
321	$old;	590	$old;
322	}	591	}
323		592
		593	sub transfer {
		594	require Carp;
		595	Carp::croak ("You must not call ->transfer on Coro objects. Use Coro::State objects or the ->schedule_to method. Caught");
		596	}
		597
324	=back	598	=back
325		599
		600	=head1 GLOBAL FUNCTIONS
		601
		602	=over 4
		603
		604	=item Coro::nready
		605
		606	Returns the number of coro that are currently in the ready state,
		607	i.e. that can be switched to by calling C<schedule> directory or
		608	indirectly. The value C<0> means that the only runnable coro is the
		609	currently running one, so C<cede> would have no effect, and C<schedule>
		610	would cause a deadlock unless there is an idle handler that wakes up some
		611	coro.
		612
		613	=item my $guard = Coro::guard { ... }
		614
		615	This function still exists, but is deprecated. Please use the
		616	C<Guard::guard> function instead.
		617
		618	=cut
		619
		620	BEGIN { *guard = \&Guard::guard }
		621
		622	=item unblock_sub { ... }
		623
		624	This utility function takes a BLOCK or code reference and "unblocks" it,
		625	returning a new coderef. Unblocking means that calling the new coderef
		626	will return immediately without blocking, returning nothing, while the
		627	original code ref will be called (with parameters) from within another
		628	coro.
		629
		630	The reason this function exists is that many event libraries (such as the
		631	venerable L<Event\|Event> module) are not thread-safe (a weaker form
		632	of reentrancy). This means you must not block within event callbacks,
		633	otherwise you might suffer from crashes or worse. The only event library
		634	currently known that is safe to use without C<unblock_sub> is L<EV>.
		635
		636	This function allows your callbacks to block by executing them in another
		637	coro where it is safe to block. One example where blocking is handy
		638	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		639	disk, for example.
		640
		641	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		642	creating event callbacks that want to block.
		643
		644	If your handler does not plan to block (e.g. simply sends a message to
		645	another coro, or puts some other coro into the ready queue), there is
		646	no reason to use C<unblock_sub>.
		647
		648	Note that you also need to use C<unblock_sub> for any other callbacks that
		649	are indirectly executed by any C-based event loop. For example, when you
		650	use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it
		651	provides callbacks that are the result of some event callback, then you
		652	must not block either, or use C<unblock_sub>.
		653
		654	=cut
		655
		656	our @unblock_queue;
		657
		658	# we create a special coro because we want to cede,
		659	# to reduce pressure on the coro pool (because most callbacks
		660	# return immediately and can be reused) and because we cannot cede
		661	# inside an event callback.
		662	our $unblock_scheduler = new Coro sub {
		663	while () {
		664	while (my $cb = pop @unblock_queue) {
		665	&async_pool (@$cb);
		666
		667	# for short-lived callbacks, this reduces pressure on the coro pool
		668	# as the chance is very high that the async_poll coro will be back
		669	# in the idle state when cede returns
		670	cede;
		671	}
		672	schedule; # sleep well
		673	}
		674	};
		675	$unblock_scheduler->{desc} = "[unblock_sub scheduler]";
		676
		677	sub unblock_sub(&) {
		678	my $cb = shift;
		679
		680	sub {
		681	unshift @unblock_queue, [$cb, @_];
		682	$unblock_scheduler->ready;
		683	}
		684	}
		685
		686	=item $cb = Coro::rouse_cb
		687
		688	Create and return a "rouse callback". That's a code reference that,
		689	when called, will remember a copy of its arguments and notify the owner
		690	coro of the callback.
		691
		692	See the next function.
		693
		694	=item @args = Coro::rouse_wait [$cb]
		695
		696	Wait for the specified rouse callback (or the last one that was created in
		697	this coro).
		698
		699	As soon as the callback is invoked (or when the callback was invoked
		700	before C<rouse_wait>), it will return the arguments originally passed to
		701	the rouse callback.
		702
		703	See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example.
		704
		705	=back
		706
326	=cut	707	=cut
327		708
328	1;	709	1;
329		710
		711	=head1 HOW TO WAIT FOR A CALLBACK
		712
		713	It is very common for a coro to wait for some callback to be
		714	called. This occurs naturally when you use coro in an otherwise
		715	event-based program, or when you use event-based libraries.
		716
		717	These typically register a callback for some event, and call that callback
		718	when the event occured. In a coro, however, you typically want to
		719	just wait for the event, simplyifying things.
		720
		721	For example C<< AnyEvent->child >> registers a callback to be called when
		722	a specific child has exited:
		723
		724	my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... });
		725
		726	But from within a coro, you often just want to write this:
		727
		728	my $status = wait_for_child $pid;
		729
		730	Coro offers two functions specifically designed to make this easy,
		731	C<Coro::rouse_cb> and C<Coro::rouse_wait>.
		732
		733	The first function, C<rouse_cb>, generates and returns a callback that,
		734	when invoked, will save its arguments and notify the coro that
		735	created the callback.
		736
		737	The second function, C<rouse_wait>, waits for the callback to be called
		738	(by calling C<schedule> to go to sleep) and returns the arguments
		739	originally passed to the callback.
		740
		741	Using these functions, it becomes easy to write the C<wait_for_child>
		742	function mentioned above:
		743
		744	sub wait_for_child($) {
		745	my ($pid) = @_;
		746
		747	my $watcher = AnyEvent->child (pid => $pid, cb => Coro::rouse_cb);
		748
		749	my ($rpid, $rstatus) = Coro::rouse_wait;
		750	$rstatus
		751	}
		752
		753	In the case where C<rouse_cb> and C<rouse_wait> are not flexible enough,
		754	you can roll your own, using C<schedule>:
		755
		756	sub wait_for_child($) {
		757	my ($pid) = @_;
		758
		759	# store the current coro in $current,
		760	# and provide result variables for the closure passed to ->child
		761	my $current = $Coro::current;
		762	my ($done, $rstatus);
		763
		764	# pass a closure to ->child
		765	my $watcher = AnyEvent->child (pid => $pid, cb => sub {
		766	$rstatus = $_[1]; # remember rstatus
		767	$done = 1; # mark $rstatus as valud
		768	});
		769
		770	# wait until the closure has been called
		771	schedule while !$done;
		772
		773	$rstatus
		774	}
		775
		776
330	=head1 BUGS/LIMITATIONS	777	=head1 BUGS/LIMITATIONS
331		778
332	- you must make very sure that no coro is still active on global	779	=over 4
333	destruction. very bad things might happen otherwise (usually segfaults).
334		780
		781	=item fork with pthread backend
		782
		783	When Coro is compiled using the pthread backend (which isn't recommended
		784	but required on many BSDs as their libcs are completely broken), then
		785	coro will not survive a fork. There is no known workaround except to
		786	fix your libc and use a saner backend.
		787
		788	=item perl process emulation ("threads")
		789
335	- this module is not thread-safe. You should only ever use this module	790	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	791	module from the first thread (this requirement might be removed in the
337	to allow per-thread schedulers, but Coro::State does not yet allow	792	future to allow per-thread schedulers, but Coro::State does not yet allow
338	this).	793	this). I recommend disabling thread support and using processes, as having
		794	the windows process emulation enabled under unix roughly halves perl
		795	performance, even when not used.
		796
		797	=item coro switching is not signal safe
		798
		799	You must not switch to another coro from within a signal handler
		800	(only relevant with %SIG - most event libraries provide safe signals).
		801
		802	That means you I<MUST NOT> call any function that might "block" the
		803	current coro - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or
		804	anything that calls those. Everything else, including calling C<ready>,
		805	works.
		806
		807	=back
		808
339		809
340	=head1 SEE ALSO	810	=head1 SEE ALSO
341		811
342	L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,	812	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>,	813
344	L<Coro::Handle>, L<Coro::RWLock>, L<Coro::Socket>.	814	Debugging: L<Coro::Debug>.
		815
		816	Support/Utility: L<Coro::Specific>, L<Coro::Util>.
		817
		818	Locking and IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>,
		819	L<Coro::SemaphoreSet>, L<Coro::RWLock>.
		820
		821	I/O and Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>.
		822
		823	Compatibility with other modules: L<Coro::LWP> (but see also L<AnyEvent::HTTP> for
		824	a better-working alternative), L<Coro::BDB>, L<Coro::Storable>,
		825	L<Coro::Select>.
		826
		827	XS API: L<Coro::MakeMaker>.
		828
		829	Low level Configuration, Thread Environment, Continuations: L<Coro::State>.
345		830
346	=head1 AUTHOR	831	=head1 AUTHOR
347		832
348	Marc Lehmann <schmorp@schmorp.de>	833	Marc Lehmann <schmorp@schmorp.de>
349	http://home.schmorp.de/	834	http://home.schmorp.de/

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Comparing Coro/Coro.pm (file contents): Revision 1.66 by root, Thu Mar 3 17:20:31 2005 UTC vs. Revision 1.249 by root, Mon Dec 15 15:21:25 2008 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.66 by root, Thu Mar 3 17:20:31 2005 UTC vs.
Revision 1.249 by root, Mon Dec 15 15:21:25 2008 UTC