[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 1.99 by root, Tue Dec 5 12:50:04 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
24	Threads but don't run in parallel.	24	to threads but don't run in parallel at the same time even on SMP
		25	machines. The specific flavor of coroutine use din this module also
		26	guarentees you that it will not switch between coroutines unless
		27	necessary, at easily-identified points in your program, so locking and
		28	parallel access are rarely an issue, making coroutine programming much
		29	safer than threads programming.
25		30
26	This module is still experimental, see the BUGS section below.	31	(Perl, however, does not natively support real threads but instead does a
		32	very slow and memory-intensive emulation of processes using threads. This
		33	is a performance win on Windows machines, and a loss everywhere else).
27		34
28	In this module, coroutines are defined as "callchain + lexical variables	35	In this module, coroutines are defined as "callchain + lexical variables +
29	+ @_ + $_ + $@ + $^W), that is, a coroutine has it's own callchain, it's	36	@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,
30	own set of lexicals and it's own set of perl's most important global	37	its own set of lexicals and its own set of perls most important global
31	variables.	38	variables.
32		39
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
49	=cut	40	=cut
50		41
51	package Coro;	42	package Coro;
52		43
		44	use strict;
		45	no warnings "uninitialized";
		46
53	use Coro::State;	47	use Coro::State;
54		48
55	use base Exporter;	49	use base qw(Coro::State Exporter);
56		50
57	$VERSION = 0.10;	51	our $idle; # idle handler
		52	our $main; # main coroutine
		53	our $current; # current coroutine
58		54
		55	our $VERSION = '3.11';
		56
59	@EXPORT = qw(async cede schedule terminate current);	57	our @EXPORT = qw(async cede schedule terminate current unblock_sub);
60	@EXPORT_OK = qw($current);	58	our %EXPORT_TAGS = (
		59	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
		60	);
		61	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
61		62
62	{	63	{
63	my @async;	64	my @async;
		65	my $init;
64		66
65	# this way of handling attributes simply is NOT scalable ;()	67	# this way of handling attributes simply is NOT scalable ;()
66	sub import {	68	sub import {
		69	no strict 'refs';
		70
67	Coro->export_to_level(1, @_);	71	Coro->export_to_level (1, @_);
		72
68	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};	73	my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
69	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {	74	*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
70	my ($package, $ref) = (shift, shift);	75	my ($package, $ref) = (shift, shift);
71	my @attrs;	76	my @attrs;
72	for (@_) {	77	for (@_) {
73	if ($_ eq "Coro") {	78	if ($_ eq "Coro") {
74	push @async, $ref;	79	push @async, $ref;
		80	unless ($init++) {
		81	eval q{
		82	sub INIT {
		83	&async(pop @async) while @async;
		84	}
		85	};
		86	}
75	} else {	87	} else {
76	push @attrs, $_;	88	push @attrs, $_;
77	}	89	}
78	}	90	}
79	return $old ? $old->($package, $ref, @attrs) : @attrs;	91	return $old ? $old->($package, $ref, @attrs) : @attrs;
80	};	92	};
81	}	93	}
82		94
83	sub INIT {
84	&async(pop @async) while @async;
85	}
86	}	95	}
		96
		97	=over 4
87		98
88	=item $main	99	=item $main
89		100
90	This coroutine represents the main program.	101	This coroutine represents the main program.
91		102
92	=cut	103	=cut
93		104
94	our $main = new Coro;	105	$main = new Coro;
95		106
96	=item $current (or as function: current)	107	=item $current (or as function: current)
97		108
98	The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).	109	The current coroutine (the last coroutine switched to). The initial value
		110	is C<$main> (of course).
		111
		112	This variable is B<strictly> I<read-only>. It is provided for performance
		113	reasons. If performance is not essentiel you are encouraged to use the
		114	C<Coro::current> function instead.
99		115
100	=cut	116	=cut
101		117
102	# maybe some other module used Coro::Specific before...	118	# maybe some other module used Coro::Specific before...
103	if ($current) {
104	$main->{specific} = $current->{specific};	119	$main->{specific} = $current->{specific}
105	}	120	if $current;
106		121
107	our $current = $main;	122	_set_current $main;
108		123
109	sub current() { $current }	124	sub current() { $current }
110		125
111	=item $idle	126	=item $idle
112		127
113	The coroutine to switch to when no other coroutine is running. The default	128	A callback that is called whenever the scheduler finds no ready coroutines
114	implementation prints "FATAL: deadlock detected" and exits.	129	to run. The default implementation prints "FATAL: deadlock detected" and
		130	exits, because the program has no other way to continue.
115		131
116	=cut	132	This hook is overwritten by modules such as C<Coro::Timer> and
		133	C<Coro::Event> to wait on an external event that hopefully wake up a
		134	coroutine so the scheduler can run it.
117		135
118	# should be done using priorities :(	136	Please note that if your callback recursively invokes perl (e.g. for event
119	our $idle = new Coro sub {	137	handlers), then it must be prepared to be called recursively.
120	print STDERR "FATAL: deadlock detected\n";	138
121	exit(51);	139	=cut
		140
		141	$idle = sub {
		142	require Carp;
		143	Carp::croak ("FATAL: deadlock detected");
122	};	144	};
123		145
124	# we really need priorities...	146	# this coroutine is necessary because a coroutine
125	my @ready; # the ready queue. hehe, rather broken ;)	147	# cannot destroy itself.
		148	my @destroy;
		149	my $manager; $manager = new Coro sub {
		150	while () {
		151	# by overwriting the state object with the manager we destroy it
		152	# while still being able to schedule this coroutine (in case it has
		153	# been readied multiple times. this is harmless since the manager
		154	# can be called as many times as neccessary and will always
		155	# remove itself from the runqueue
		156	while (@destroy) {
		157	my $coro = pop @destroy;
		158	$coro->{status} \|\|= [];
		159	$_->ready for @{delete $coro->{join} \|\| []};
		160
		161	# the next line destroys the coro state, but keeps the
		162	# coroutine itself intact (we basically make it a zombie
		163	# coroutine that always runs the manager thread, so it's possible
		164	# to transfer() to this coroutine).
		165	$coro->_clone_state_from ($manager);
		166	}
		167	&schedule;
		168	}
		169	};
126		170
127	# static methods. not really.	171	# static methods. not really.
128		172
		173	=back
		174
129	=head2 STATIC METHODS	175	=head2 STATIC METHODS
130		176
131	Static methods are actually functions that operate on the current process only.	177	Static methods are actually functions that operate on the current coroutine only.
132		178
133	=over 4	179	=over 4
134		180
135	=item async { ... } [@args...]	181	=item async { ... } [@args...]
136		182
137	Create a new asynchronous process and return it's process object	183	Create a new asynchronous coroutine and return it's coroutine object
138	(usually unused). When the sub returns the new process is automatically	184	(usually unused). When the sub returns the new coroutine is automatically
139	terminated.	185	terminated.
		186
		187	Calling C<exit> in a coroutine will not work correctly, so do not do that.
		188
		189	When the coroutine dies, the program will exit, just as in the main
		190	program.
140		191
141	# create a new coroutine that just prints its arguments	192	# create a new coroutine that just prints its arguments
142	async {	193	async {
143	print "@_\n";	194	print "@_\n";
144	} 1,2,3,4;	195	} 1,2,3,4;
145		196
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	197	=cut
150		198
151	sub async(&@) {	199	sub async(&@) {
152	my $pid = new Coro @_;	200	my $pid = new Coro @_;
153	$pid->ready;	201	$pid->ready;
154	$pid;	202	$pid
155	}	203	}
156		204
157	=item schedule	205	=item schedule
158		206
159	Calls the scheduler. Please note that the current process will not be put	207	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	208	into the ready queue, so calling this function usually means you will
161	never be called again.	209	never be called again unless something else (e.g. an event handler) calls
		210	ready.
162		211
163	=cut	212	The canonical way to wait on external events is this:
164		213
165	my $prev;	214	{
		215	# remember current coroutine
		216	my $current = $Coro::current;
166		217
167	sub schedule {	218	# register a hypothetical event handler
168	# should be done using priorities :(	219	on_event_invoke sub {
169	($prev, $current) = ($current, shift @ready \|\| $idle);	220	# wake up sleeping coroutine
170	Coro::State::transfer($prev, $current);	221	$current->ready;
171	}	222	undef $current;
		223	};
		224
		225	# call schedule until event occured.
		226	# in case we are woken up for other reasons
		227	# (current still defined), loop.
		228	Coro::schedule while $current;
		229	}
172		230
173	=item cede	231	=item cede
174		232
175	"Cede" to other processes. This function puts the current process into the	233	"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	234	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.	235	current "timeslice" to other coroutines of the same or higher priority.
178		236
179	=cut
180
181	sub cede {
182	$current->ready;
183	&schedule;
184	}
185
186	=item terminate	237	=item terminate [arg...]
187		238
188	Terminates the current process.	239	Terminates the current coroutine with the given status values (see L<cancel>).
189
190	Future versions of this function will allow result arguments.
191		240
192	=cut	241	=cut
193		242
194	sub terminate {	243	sub terminate {
195	my $self = $current;	244	$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	}	245	}
202		246
203	=back	247	=back
204		248
205	# dynamic methods	249	# dynamic methods
206		250
207	=head2 PROCESS METHODS	251	=head2 COROUTINE METHODS
208		252
209	These are the methods you can call on process objects.	253	These are the methods you can call on coroutine objects.
210		254
211	=over 4	255	=over 4
212		256
213	=item new Coro \&sub [, @args...]	257	=item new Coro \&sub [, @args...]
214		258
215	Create a new process and return it. When the sub returns the process	259	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	260	automatically terminates as if C<terminate> with the returned values were
		261	called. To make the coroutine run you must first put it into the ready queue
217	the ready queue by calling the ready method.	262	by calling the ready method.
218		263
219	The coderef you submit MUST NOT be a closure that refers to variables	264	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		265
222	=cut	266	=cut
223		267
224	sub _newcoro {	268	sub _run_coro {
225	terminate &{+shift};	269	terminate &{+shift};
226	}	270	}
227		271
228	sub new {	272	sub new {
229	my $class = shift;	273	my $class = shift;
230	bless {
231	_coro_state => (new Coro::State $_[0] && \&_newcoro, @_),
232	}, $class;
233	}
234		274
235	=item $process->ready	275	$class->SUPER::new (\&_run_coro, @_)
		276	}
236		277
237	Put the current process into the ready queue.	278	=item $success = $coroutine->ready
238		279
239	=cut	280	Put the given coroutine into the ready queue (according to it's priority)
		281	and return true. If the coroutine is already in the ready queue, do nothing
		282	and return false.
240		283
241	sub ready {	284	=item $is_ready = $coroutine->is_ready
242	push @ready, $_[0];	285
		286	Return wether the coroutine is currently the ready queue or not,
		287
		288	=item $coroutine->cancel (arg...)
		289
		290	Terminates the given coroutine and makes it return the given arguments as
		291	status (default: the empty list).
		292
		293	=cut
		294
		295	sub cancel {
		296	my $self = shift;
		297	$self->{status} = [@_];
		298	push @destroy, $self;
		299	$manager->ready;
		300	&schedule if $current == $self;
		301	}
		302
		303	=item $coroutine->join
		304
		305	Wait until the coroutine terminates and return any values given to the
		306	C<terminate> or C<cancel> functions. C<join> can be called multiple times
		307	from multiple coroutine.
		308
		309	=cut
		310
		311	sub join {
		312	my $self = shift;
		313	unless ($self->{status}) {
		314	push @{$self->{join}}, $current;
		315	&schedule;
		316	}
		317	wantarray ? @{$self->{status}} : $self->{status}[0];
		318	}
		319
		320	=item $oldprio = $coroutine->prio ($newprio)
		321
		322	Sets (or gets, if the argument is missing) the priority of the
		323	coroutine. Higher priority coroutines get run before lower priority
		324	coroutines. Priorities are small signed integers (currently -4 .. +3),
		325	that you can refer to using PRIO_xxx constants (use the import tag :prio
		326	to get then):
		327
		328	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
		329	3 > 1 > 0 > -1 > -3 > -4
		330
		331	# set priority to HIGH
		332	current->prio(PRIO_HIGH);
		333
		334	The idle coroutine ($Coro::idle) always has a lower priority than any
		335	existing coroutine.
		336
		337	Changing the priority of the current coroutine will take effect immediately,
		338	but changing the priority of coroutines in the ready queue (but not
		339	running) will only take effect after the next schedule (of that
		340	coroutine). This is a bug that will be fixed in some future version.
		341
		342	=item $newprio = $coroutine->nice ($change)
		343
		344	Similar to C<prio>, but subtract the given value from the priority (i.e.
		345	higher values mean lower priority, just as in unix).
		346
		347	=item $olddesc = $coroutine->desc ($newdesc)
		348
		349	Sets (or gets in case the argument is missing) the description for this
		350	coroutine. This is just a free-form string you can associate with a coroutine.
		351
		352	=cut
		353
		354	sub desc {
		355	my $old = $_[0]{desc};
		356	$_[0]{desc} = $_[1] if @_ > 1;
		357	$old;
243	}	358	}
244		359
245	=back	360	=back
246		361
		362	=head2 GLOBAL FUNCTIONS
		363
		364	=over 4
		365
		366	=item Coro::nready
		367
		368	Returns the number of coroutines that are currently in the ready state,
		369	i.e. that can be swicthed to. The value C<0> means that the only runnable
		370	coroutine is the currently running one, so C<cede> would have no effect,
		371	and C<schedule> would cause a deadlock unless there is an idle handler
		372	that wakes up some coroutines.
		373
		374	=item unblock_sub { ... }
		375
		376	This utility function takes a BLOCK or code reference and "unblocks" it,
		377	returning the new coderef. This means that the new coderef will return
		378	immediately without blocking, returning nothing, while the original code
		379	ref will be called (with parameters) from within its own coroutine.
		380
		381	The reason this fucntion exists is that many event libraries (such as the
		382	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form
		383	of thread-safety). This means you must not block within event callbacks,
		384	otherwise you might suffer from crashes or worse.
		385
		386	This function allows your callbacks to block by executing them in another
		387	coroutine where it is safe to block. One example where blocking is handy
		388	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
		389	disk.
		390
		391	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
		392	creating event callbacks that want to block.
		393
		394	=cut
		395
		396	our @unblock_pool;
		397	our @unblock_queue;
		398	our $UNBLOCK_POOL_SIZE = 2;
		399
		400	sub unblock_handler_ {
		401	while () {
		402	my ($cb, @arg) = @{ delete $Coro::current->{arg} };
		403	$cb->(@arg);
		404
		405	last if @unblock_pool >= $UNBLOCK_POOL_SIZE;
		406	push @unblock_pool, $Coro::current;
		407	schedule;
		408	}
		409	}
		410
		411	our $unblock_scheduler = async {
		412	while () {
		413	while (my $cb = pop @unblock_queue) {
		414	my $handler = (pop @unblock_pool or new Coro \&unblock_handler_);
		415	$handler->{arg} = $cb;
		416	$handler->ready;
		417	cede;
		418	}
		419
		420	schedule;
		421	}
		422	};
		423
		424	sub unblock_sub(&) {
		425	my $cb = shift;
		426
		427	sub {
		428	push @unblock_queue, [$cb, @_];
		429	$unblock_scheduler->ready;
		430	}
		431	}
		432
		433	=back
		434
247	=cut	435	=cut
248		436
249	1;	437	1;
250		438
251	=head1 BUGS/LIMITATIONS	439	=head1 BUGS/LIMITATIONS
252		440
253	- could be faster, especially when the core would introduce special	441	- you must make very sure that no coro is still active on global
254	support for coroutines (like it does for threads).	442	destruction. very bad things might happen otherwise (usually segfaults).
255	- there is still a memleak on coroutine termination that I could not	443
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	444	- 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	445	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).	446	to allow per-thread schedulers, but Coro::State does not yet allow
		447	this).
264		448
265	=head1 SEE ALSO	449	=head1 SEE ALSO
266		450
267	L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,	451	Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.
268	L<Coro::Signal>, L<Coro::State>, L<Coro::Event>.	452
		453	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
		454
		455	Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.
		456
		457	Embedding: L<Coro:MakeMaker>
269		458
270	=head1 AUTHOR	459	=head1 AUTHOR
271		460
272	Marc Lehmann <pcg@goof.com>	461	Marc Lehmann <schmorp@schmorp.de>
273	http://www.goof.com/pcg/marc/	462	http://home.schmorp.de/
274		463
275	=cut	464	=cut
276		465

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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 1.99 by root, Tue Dec 5 12:50:04 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 1.99 by root, Tue Dec 5 12:50:04 2006 UTC