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

Comparing Coro/Coro.pm (file contents):
Revision 1.22 by root, Mon Jul 23 02:14:19 2001 UTC vs.
Revision 1.92 by root, Fri Dec 1 03:47:55 2006 UTC

…		…
8		8
9	async {	9	async {
10	# some asynchronous thread of execution	10	# some asynchronous thread of execution
11	};	11	};
12		12
13	# alternatively create an async process like this:	13	# alternatively create an async coroutine like this:
14		14
15	sub some_func : Coro {	15	sub some_func : Coro {
16	# some more async code	16	# some more async code
17	}	17	}
18		18
19	cede;	19	cede;
20		20
21	=head1 DESCRIPTION	21	=head1 DESCRIPTION
22		22
23	This module collection manages coroutines. Coroutines are similar to	23	This module collection manages coroutines. Coroutines are similar to
24	Threads but don't run in parallel.	24	threads but don't run in parallel.
25
26	This module is still experimental, see the BUGS section below.
27		25
28	In this module, coroutines are defined as "callchain + lexical variables	26	In this module, coroutines are defined as "callchain + lexical variables
29	+ @_ + $_ + $@ + $^W), that is, a coroutine has it's own callchain, it's	27	+ @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own
30	own set of lexicals and it's own set of perl's most important global	28	callchain, it's own set of lexicals and it's own set of perl's most
31	variables.	29	important global variables.
32
33	WARNING: When using this module, make sure that, at program end, no
34	coroutines are still running OR just call exit before falling off the
35	end. The reason for this is that some coroutine of yours might have called
36	into a C function, and falling off the end of main:: results in returning
37	to that C function instead if to the main C interpreter.
38
39	WARNING: Unless you really know what you are doing, do NOT do context
40	switches inside callbacks from the XS level. The reason for this is
41	similar to the reason above: A callback calls a perl function, this
42	perl function does a context switch, some other callback is called, the
43	original function returns from it - to what? To the wrong XS function,
44	with totally different return values. Unfortunately, this includes
45	callbacks done by perl itself (tie'd variables!).
46
47	The only workaround for this is to do coroutines on C level.
48		30
49	=cut	31	=cut
50		32
51	package Coro;	33	package Coro;
52		34
		35	use strict;
		36	no warnings "uninitialized";
		37
53	use Coro::State;	38	use Coro::State;
54		39
55	use base Exporter;	40	use base qw(Coro::State Exporter);
56		41
57	$VERSION = 0.10;	42	our $idle; # idle handler
		43	our $main; # main coroutine
		44	our $current; # current coroutine
58		45
		46	our $VERSION = '3.0';
		47
59	@EXPORT = qw(async cede schedule terminate current);	48	our @EXPORT = qw(async cede schedule terminate current unblock_sub);
60	@EXPORT_OK = qw($current);	49	our %EXPORT_TAGS = (
		50	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
		51	);
		52	our @EXPORT_OK = @{$EXPORT_TAGS{prio}};
61		53
62	{	54	{
63	my @async;	55	my @async;
		56	my $init;
64		57
65	# this way of handling attributes simply is NOT scalable ;()	58	# this way of handling attributes simply is NOT scalable ;()
66	sub import {	59	sub import {
		60	no strict 'refs';
		61
67	Coro->export_to_level(1, @_);	62	Coro->export_to_level(1, @_);
		63
68	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};	64	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
69	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {	65	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
70	my ($package, $ref) = (shift, shift);	66	my ($package, $ref) = (shift, shift);
71	my @attrs;	67	my @attrs;
72	for (@_) {	68	for (@_) {
73	if ($_ eq "Coro") {	69	if ($_ eq "Coro") {
74	push @async, $ref;	70	push @async, $ref;
		71	unless ($init++) {
		72	eval q{
		73	sub INIT {
		74	&async(pop @async) while @async;
		75	}
		76	};
		77	}
75	} else {	78	} else {
76	push @attrs, $_;	79	push @attrs, $_;
77	}	80	}
78	}	81	}
79	return $old ? $old->($package, $ref, @attrs) : @attrs;	82	return $old ? $old->($package, $ref, @attrs) : @attrs;
80	};	83	};
81	}	84	}
82		85
83	sub INIT {
84	&async(pop @async) while @async;
85	}
86	}	86	}
		87
		88	=over 4
87		89
88	=item $main	90	=item $main
89		91
90	This coroutine represents the main program.	92	This coroutine represents the main program.
91		93
92	=cut	94	=cut
93		95
94	our $main = new Coro;	96	$main = new Coro;
95		97
96	=item $current (or as function: current)	98	=item $current (or as function: current)
97		99
98	The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).	100	The current coroutine (the last coroutine switched to). The initial value
		101	is C<$main> (of course).
		102
		103	This variable is B<strictly> I<read-only>. It is provided for performance
		104	reasons. If performance is not essentiel you are encouraged to use the
		105	C<Coro::current> function instead.
99		106
100	=cut	107	=cut
101		108
102	# maybe some other module used Coro::Specific before...	109	# maybe some other module used Coro::Specific before...
103	if ($current) {	110	if ($current) {
104	$main->{specific} = $current->{specific};	111	$main->{specific} = $current->{specific};
105	}	112	}
106		113
107	our $current = $main;	114	$current = $main;
108		115
109	sub current() { $current }	116	sub current() { $current }
110		117
111	=item $idle	118	=item $idle
112		119
113	The coroutine to switch to when no other coroutine is running. The default	120	A callback that is called whenever the scheduler finds no ready coroutines
114	implementation prints "FATAL: deadlock detected" and exits.	121	to run. The default implementation prints "FATAL: deadlock detected" and
		122	exits, because the program has no other way to continue.
115		123
116	=cut	124	This hook is overwritten by modules such as C<Coro::Timer> and
		125	C<Coro::Event> to wait on an external event that hopefully wake up a
		126	coroutine so the scheduler can run it.
117		127
118	# should be done using priorities :(	128	Please note that if your callback recursively invokes perl (e.g. for event
119	our $idle = new Coro sub {	129	handlers), then it must be prepared to be called recursively.
		130
		131	=cut
		132
		133	$idle = sub {
120	print STDERR "FATAL: deadlock detected\n";	134	print STDERR "FATAL: deadlock detected\n";
121	exit(51);	135	exit (51);
122	};	136	};
123		137
124	# we really need priorities...	138	# this coroutine is necessary because a coroutine
125	my @ready; # the ready queue. hehe, rather broken ;)	139	# cannot destroy itself.
		140	my @destroy;
		141	my $manager; $manager = new Coro sub {
		142	while () {
		143	# by overwriting the state object with the manager we destroy it
		144	# while still being able to schedule this coroutine (in case it has
		145	# been readied multiple times. this is harmless since the manager
		146	# can be called as many times as neccessary and will always
		147	# remove itself from the runqueue
		148	while (@destroy) {
		149	my $coro = pop @destroy;
		150	$coro->{status} \|\|= [];
		151	$_->ready for @{delete $coro->{join} \|\| []};
		152
		153	# the next line destroys the coro state, but keeps the
		154	# coroutine itself intact (we basically make it a zombie
		155	# coroutine that always runs the manager thread, so it's possible
		156	# to transfer() to this coroutine).
		157	$coro->_clone_state_from ($manager);
		158	}
		159	&schedule;
		160	}
		161	};
126		162
127	# static methods. not really.	163	# static methods. not really.
128		164
		165	=back
		166
129	=head2 STATIC METHODS	167	=head2 STATIC METHODS
130		168
131	Static methods are actually functions that operate on the current process only.	169	Static methods are actually functions that operate on the current coroutine only.
132		170
133	=over 4	171	=over 4
134		172
135	=item async { ... } [@args...]	173	=item async { ... } [@args...]
136		174
137	Create a new asynchronous process and return it's process object	175	Create a new asynchronous coroutine and return it's coroutine object
138	(usually unused). When the sub returns the new process is automatically	176	(usually unused). When the sub returns the new coroutine is automatically
139	terminated.	177	terminated.
		178
		179	Calling C<exit> in a coroutine will not work correctly, so do not do that.
		180
		181	When the coroutine dies, the program will exit, just as in the main
		182	program.
140		183
141	# create a new coroutine that just prints its arguments	184	# create a new coroutine that just prints its arguments
142	async {	185	async {
143	print "@_\n";	186	print "@_\n";
144	} 1,2,3,4;	187	} 1,2,3,4;
145		188
146	The coderef you submit MUST NOT be a closure that refers to variables
147	in an outer scope. This does NOT work. Pass arguments into it instead.
148
149	=cut	189	=cut
150		190
151	sub async(&@) {	191	sub async(&@) {
152	my $pid = new Coro @_;	192	my $pid = new Coro @_;
153	$pid->ready;	193	$pid->ready;
154	$pid;	194	$pid
155	}	195	}
156		196
157	=item schedule	197	=item schedule
158		198
159	Calls the scheduler. Please note that the current process will not be put	199	Calls the scheduler. Please note that the current coroutine will not be put
160	into the ready queue, so calling this function usually means you will	200	into the ready queue, so calling this function usually means you will
161	never be called again.	201	never be called again unless something else (e.g. an event handler) calls
		202	ready.
162		203
163	=cut	204	The canonical way to wait on external events is this:
164		205
165	my $prev;	206	{
		207	# remember current coroutine
		208	my $current = $Coro::current;
166		209
167	sub schedule {	210	# register a hypothetical event handler
168	# should be done using priorities :(	211	on_event_invoke sub {
169	($prev, $current) = ($current, shift @ready \|\| $idle);	212	# wake up sleeping coroutine
170	Coro::State::transfer($prev, $current);	213	$current->ready;
171	}	214	undef $current;
		215	};
		216
		217	# call schedule until event occured.
		218	# in case we are woken up for other reasons
		219	# (current still defined), loop.
		220	Coro::schedule while $current;
		221	}
172		222
173	=item cede	223	=item cede
174		224
175	"Cede" to other processes. This function puts the current process into the	225	"Cede" to other coroutines. This function puts the current coroutine into the
176	ready queue and calls C<schedule>, which has the effect of giving up the	226	ready queue and calls C<schedule>, which has the effect of giving up the
177	current "timeslice" to other coroutines of the same or higher priority.	227	current "timeslice" to other coroutines of the same or higher priority.
178		228
179	=cut
180
181	sub cede {
182	$current->ready;
183	&schedule;
184	}
185
186	=item terminate	229	=item terminate [arg...]
187		230
188	Terminates the current process.	231	Terminates the current coroutine with the given status values (see L<cancel>).
189
190	Future versions of this function will allow result arguments.
191		232
192	=cut	233	=cut
193		234
194	sub terminate {	235	sub terminate {
195	my $self = $current;	236	$current->cancel (@_);
196	$self->{_results} = [@_];
197	$current = shift @ready \|\| $idle;
198	Coro::State::transfer(delete $self->{_coro_state}, $current);
199	# cannot return
200	die;
201	}	237	}
202		238
203	=back	239	=back
204		240
205	# dynamic methods	241	# dynamic methods
206		242
207	=head2 PROCESS METHODS	243	=head2 COROUTINE METHODS
208		244
209	These are the methods you can call on process objects.	245	These are the methods you can call on coroutine objects.
210		246
211	=over 4	247	=over 4
212		248
213	=item new Coro \&sub [, @args...]	249	=item new Coro \&sub [, @args...]
214		250
215	Create a new process and return it. When the sub returns the process	251	Create a new coroutine and return it. When the sub returns the coroutine
216	automatically terminates. To start the process you must first put it into	252	automatically terminates as if C<terminate> with the returned values were
		253	called. To make the coroutine run you must first put it into the ready queue
217	the ready queue by calling the ready method.	254	by calling the ready method.
218		255
219	The coderef you submit MUST NOT be a closure that refers to variables	256	Calling C<exit> in a coroutine will not work correctly, so do not do that.
220	in an outer scope. This does NOT work. Pass arguments into it instead.
221		257
222	=cut	258	=cut
223		259
224	sub _newcoro {	260	sub _new_coro {
225	terminate &{+shift};	261	terminate &{+shift};
226	}	262	}
227		263
228	sub new {	264	sub new {
229	my $class = shift;	265	my $class = shift;
230	bless {
231	_coro_state => (new Coro::State $_[0] && \&_newcoro, @_),
232	}, $class;
233	}
234		266
235	=item $process->ready	267	$class->SUPER::new (\&_new_coro, @_)
		268	}
236		269
237	Put the current process into the ready queue.	270	=item $success = $coroutine->ready
238		271
239	=cut	272	Put the given coroutine into the ready queue (according to it's priority)
		273	and return true. If the coroutine is already in the ready queue, do nothing
		274	and return false.
240		275
241	sub ready {	276	=item $is_ready = $coroutine->is_ready
242	push @ready, $_[0];	277
		278	Return wether the coroutine is currently the ready queue or not,
		279
		280	=item $coroutine->cancel (arg...)
		281
		282	Terminates the given coroutine and makes it return the given arguments as
		283	status (default: the empty list).
		284
		285	=cut
		286
		287	sub cancel {
		288	my $self = shift;
		289	$self->{status} = [@_];
		290	push @destroy, $self;
		291	$manager->ready;
		292	&schedule if $current == $self;
		293	}
		294
		295	=item $coroutine->join
		296
		297	Wait until the coroutine terminates and return any values given to the
		298	C<terminate> or C<cancel> functions. C<join> can be called multiple times
		299	from multiple coroutine.
		300
		301	=cut
		302
		303	sub join {
		304	my $self = shift;
		305	unless ($self->{status}) {
		306	push @{$self->{join}}, $current;
		307	&schedule;
		308	}
		309	wantarray ? @{$self->{status}} : $self->{status}[0];
		310	}
		311
		312	=item $oldprio = $coroutine->prio ($newprio)
		313
		314	Sets (or gets, if the argument is missing) the priority of the
		315	coroutine. Higher priority coroutines get run before lower priority
		316	coroutines. Priorities are small signed integers (currently -4 .. +3),
		317	that you can refer to using PRIO_xxx constants (use the import tag :prio
		318	to get then):
		319
		320	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
		321	3 > 1 > 0 > -1 > -3 > -4
		322
		323	# set priority to HIGH
		324	current->prio(PRIO_HIGH);
		325
		326	The idle coroutine ($Coro::idle) always has a lower priority than any
		327	existing coroutine.
		328
		329	Changing the priority of the current coroutine will take effect immediately,
		330	but changing the priority of coroutines in the ready queue (but not
		331	running) will only take effect after the next schedule (of that
		332	coroutine). This is a bug that will be fixed in some future version.
		333
		334	=item $newprio = $coroutine->nice ($change)
		335
		336	Similar to C<prio>, but subtract the given value from the priority (i.e.
		337	higher values mean lower priority, just as in unix).
		338
		339	=item $olddesc = $coroutine->desc ($newdesc)
		340
		341	Sets (or gets in case the argument is missing) the description for this
		342	coroutine. This is just a free-form string you can associate with a coroutine.
		343
		344	=cut
		345
		346	sub desc {
		347	my $old = $_[0]{desc};
		348	$_[0]{desc} = $_[1] if @_ > 1;
		349	$old;
243	}	350	}
244		351
245	=back	352	=back
246		353
		354	=head2 UTILITY FUNCTIONS
		355
		356	=over 4
		357
		358	=item unblock_sub { ... }
		359
		360	This utility function takes a BLOCK or code reference and "unblocks" it,
		361	returning the new coderef. This means that the new coderef will return
		362	immediately without blocking, returning nothing, while the original code
		363	ref will be called (with parameters) from within its own coroutine.
		364
		365	The reason this fucntion exists is that many event libraries (such as the
		366	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		367	of thread-safety). This means you must not block within event callbacks,
		368	otherwise you might suffer from crashes or worse.
		369
		370	This function allows your callbacks to block by executing them in another
		371	coroutine where it is safe to block. One example where blocking is handy
		372	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		373	disk.
		374
		375	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		376	creating event callbacks that want to block.
		377
		378	=cut
		379
		380	our @unblock_pool;
		381	our @unblock_queue;
		382	our $UNBLOCK_POOL_SIZE = 2;
		383
		384	sub unblock_handler_ {
		385	while () {
		386	my ($cb, @arg) = @{ delete $Coro::current->{arg} };
		387	$cb->(@arg);
		388
		389	last if @unblock_pool >= $UNBLOCK_POOL_SIZE;
		390	push @unblock_pool, $Coro::current;
		391	schedule;
		392	}
		393	}
		394
		395	our $unblock_scheduler = async {
		396	while () {
		397	while (my $cb = pop @unblock_queue) {
		398	my $handler = (pop @unblock_pool or new Coro \&unblock_handler_);
		399	$handler->{arg} = $cb;
		400	$handler->ready;
		401	cede;
		402	}
		403
		404	schedule;
		405	}
		406	};
		407
		408	sub unblock_sub(&) {
		409	my $cb = shift;
		410
		411	sub {
		412	push @unblock_queue, [$cb, @_];
		413	$unblock_scheduler->ready;
		414	}
		415	}
		416
		417	=back
		418
247	=cut	419	=cut
248		420
249	1;	421	1;
250		422
251	=head1 BUGS/LIMITATIONS	423	=head1 BUGS/LIMITATIONS
252		424
253	- could be faster, especially when the core would introduce special	425	- you must make very sure that no coro is still active on global
254	support for coroutines (like it does for threads).	426	destruction. very bad things might happen otherwise (usually segfaults).
255	- there is still a memleak on coroutine termination that I could not	427
256	identify. Could be as small as a single SV.
257	- this module is not well-tested.
258	- if variables or arguments "disappear" (become undef) or become
259	corrupted please contact the author so he cen iron out the
260	remaining bugs.
261	- this module is not thread-safe. You must only ever use this module from	428	- this module is not thread-safe. You should only ever use this module
262	the same thread (this requirement might be loosened in the future to	429	from the same thread (this requirement might be losened in the future
263	allow per-thread schedulers, but Coro::State does not yet allow this).	430	to allow per-thread schedulers, but Coro::State does not yet allow
		431	this).
264		432
265	=head1 SEE ALSO	433	=head1 SEE ALSO
266		434
267	L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,	435	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.
268	L<Coro::Signal>, L<Coro::State>, L<Coro::Event>.	436
		437	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
		438
		439	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.
		440
		441	Embedding: L<Coro:MakeMaker>
269		442
270	=head1 AUTHOR	443	=head1 AUTHOR
271		444
272	Marc Lehmann <pcg@goof.com>	445	Marc Lehmann <schmorp@schmorp.de>
273	http://www.goof.com/pcg/marc/	446	http://home.schmorp.de/
274		447
275	=cut	448	=cut
276		449

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Comparing Coro/Coro.pm (file contents): Revision 1.22 by root, Mon Jul 23 02:14:19 2001 UTC vs. Revision 1.92 by root, Fri Dec 1 03:47:55 2006 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.22 by root, Mon Jul 23 02:14:19 2001 UTC vs.
Revision 1.92 by root, Fri Dec 1 03:47:55 2006 UTC