ViewVC Help
View File | Revision Log | Show Annotations | Download File
/cvs/Coro/Coro.pm
(Generate patch)

Comparing Coro/Coro.pm (file contents):
Revision 1.58 by pcg, Fri Feb 13 23:17:41 2004 UTC vs.
Revision 1.137 by root, Wed Sep 26 19:26:48 2007 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
23This module collection manages coroutines. Coroutines are similar to 23This module collection manages coroutines. Coroutines are similar
24threads but don't run in parallel. 24to threads but don't run in parallel at the same time even on SMP
25machines. The specific flavor of coroutine used in this module also
26guarantees you that it will not switch between coroutines unless
27necessary, at easily-identified points in your program, so locking and
28parallel access are rarely an issue, making coroutine programming much
29safer than threads programming.
25 30
31(Perl, however, does not natively support real threads but instead does a
32very slow and memory-intensive emulation of processes using threads. This
33is a performance win on Windows machines, and a loss everywhere else).
34
26In this module, coroutines are defined as "callchain + lexical variables 35In this module, coroutines are defined as "callchain + lexical variables +
27+ @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own 36@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,
28callchain, it's own set of lexicals and it's own set of perl's most 37its own set of lexicals and its own set of perls most important global
29important global variables. 38variables.
30 39
31=cut 40=cut
32 41
33package Coro; 42package Coro;
34 43
35BEGIN { eval { require warnings } && warnings->unimport ("uninitialized") } 44use strict;
45no warnings "uninitialized";
36 46
37use Coro::State; 47use Coro::State;
38 48
39use vars qw($idle $main $current); 49use base qw(Coro::State Exporter);
40 50
41use base Exporter; 51our $idle; # idle handler
52our $main; # main coroutine
53our $current; # current coroutine
42 54
43$VERSION = 0.95; 55our $VERSION = '3.7';
44 56
45@EXPORT = qw(async cede schedule terminate current); 57our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
46%EXPORT_TAGS = ( 58our %EXPORT_TAGS = (
47 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], 59 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
48); 60);
49@EXPORT_OK = @{$EXPORT_TAGS{prio}}; 61our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
50 62
51{ 63{
52 my @async; 64 my @async;
53 my $init; 65 my $init;
54 66
55 # this way of handling attributes simply is NOT scalable ;() 67 # this way of handling attributes simply is NOT scalable ;()
56 sub import { 68 sub import {
69 no strict 'refs';
70
57 Coro->export_to_level(1, @_); 71 Coro->export_to_level (1, @_);
72
58 my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE}; 73 my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
59 *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub { 74 *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
60 my ($package, $ref) = (shift, shift); 75 my ($package, $ref) = (shift, shift);
61 my @attrs; 76 my @attrs;
62 for (@_) { 77 for (@_) {
89 104
90$main = new Coro; 105$main = new Coro;
91 106
92=item $current (or as function: current) 107=item $current (or as function: current)
93 108
94The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course). 109The current coroutine (the last coroutine switched to). The initial value
110is C<$main> (of course).
95 111
112This variable is B<strictly> I<read-only>. It is provided for performance
113reasons. If performance is not essential you are encouraged to use the
114C<Coro::current> function instead.
115
96=cut 116=cut
117
118$main->{desc} = "[main::]";
97 119
98# maybe some other module used Coro::Specific before... 120# maybe some other module used Coro::Specific before...
99if ($current) {
100 $main->{specific} = $current->{specific}; 121$main->{specific} = $current->{specific}
101} 122 if $current;
102 123
103$current = $main; 124_set_current $main;
104 125
105sub current() { $current } 126sub current() { $current }
106 127
107=item $idle 128=item $idle
108 129
109The coroutine to switch to when no other coroutine is running. The default 130A callback that is called whenever the scheduler finds no ready coroutines
110implementation prints "FATAL: deadlock detected" and exits. 131to run. The default implementation prints "FATAL: deadlock detected" and
132exits, because the program has no other way to continue.
111 133
112=cut 134This hook is overwritten by modules such as C<Coro::Timer> and
135C<Coro::Event> to wait on an external event that hopefully wake up a
136coroutine so the scheduler can run it.
113 137
114# should be done using priorities :( 138Please note that if your callback recursively invokes perl (e.g. for event
115$idle = new Coro sub { 139handlers), then it must be prepared to be called recursively.
116 print STDERR "FATAL: deadlock detected\n"; 140
117 exit(51); 141=cut
142
143$idle = sub {
144 require Carp;
145 Carp::croak ("FATAL: deadlock detected");
118}; 146};
147
148sub _cancel {
149 my ($self) = @_;
150
151 # free coroutine data and mark as destructed
152 $self->_destroy
153 or return;
154
155 # call all destruction callbacks
156 $_->(@{$self->{status}})
157 for @{(delete $self->{destroy_cb}) || []};
158}
159
160sub _do_trace {
161 $current->{_trace_cb}->();
162}
119 163
120# this coroutine is necessary because a coroutine 164# this coroutine is necessary because a coroutine
121# cannot destroy itself. 165# cannot destroy itself.
122my @destroy; 166my @destroy;
123my $manager; 167my $manager;
168
124$manager = new Coro sub { 169$manager = new Coro sub {
125 while () { 170 while () {
126 # by overwriting the state object with the manager we destroy it 171 (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) { 172 while @destroy;
132 my $coro = pop @destroy; 173
133 $coro->{status} ||= [];
134 $_->ready for @{delete $coro->{join} || []};
135 $coro->{_coro_state} = $manager->{_coro_state};
136 }
137 &schedule; 174 &schedule;
138 } 175 }
139}; 176};
177$manager->desc ("[coro manager]");
178$manager->prio (PRIO_MAX);
140 179
141# static methods. not really. 180# static methods. not really.
142 181
143=back 182=back
144 183
145=head2 STATIC METHODS 184=head2 STATIC METHODS
146 185
147Static methods are actually functions that operate on the current process only. 186Static methods are actually functions that operate on the current coroutine only.
148 187
149=over 4 188=over 4
150 189
151=item async { ... } [@args...] 190=item async { ... } [@args...]
152 191
153Create a new asynchronous process and return it's process object 192Create a new asynchronous coroutine and return it's coroutine object
154(usually unused). When the sub returns the new process is automatically 193(usually unused). When the sub returns the new coroutine is automatically
155terminated. 194terminated.
195
196Calling C<exit> in a coroutine will do the same as calling exit outside
197the coroutine. Likewise, when the coroutine dies, the program will exit,
198just as it would in the main program.
156 199
157 # create a new coroutine that just prints its arguments 200 # create a new coroutine that just prints its arguments
158 async { 201 async {
159 print "@_\n"; 202 print "@_\n";
160 } 1,2,3,4; 203 } 1,2,3,4;
161 204
162=cut 205=cut
163 206
164sub async(&@) { 207sub async(&@) {
165 my $pid = new Coro @_; 208 my $coro = new Coro @_;
166 $manager->ready; # this ensures that the stack is cloned from the manager
167 $pid->ready; 209 $coro->ready;
168 $pid; 210 $coro
211}
212
213=item async_pool { ... } [@args...]
214
215Similar to C<async>, but uses a coroutine pool, so you should not call
216terminate or join (although you are allowed to), and you get a coroutine
217that might have executed other code already (which can be good or bad :).
218
219Also, the block is executed in an C<eval> context and a warning will be
220issued in case of an exception instead of terminating the program, as
221C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
222will not work in the expected way, unless you call terminate or cancel,
223which somehow defeats the purpose of pooling.
224
225The priority will be reset to C<0> after each job, otherwise the coroutine
226will be re-used "as-is".
227
228The pool size is limited to 8 idle coroutines (this can be adjusted by
229changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
230required.
231
232If you are concerned about pooled coroutines growing a lot because a
233single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
234{ terminate }> once per second or so to slowly replenish the pool. In
235addition to that, when the stacks used by a handler grows larger than 16kb
236(adjustable with $Coro::POOL_RSS) it will also exit.
237
238=cut
239
240our $POOL_SIZE = 8;
241our $POOL_RSS = 16 * 1024;
242our @async_pool;
243
244sub pool_handler {
245 my $cb;
246
247 while () {
248 eval {
249 while () {
250 _pool_1 $cb;
251 &$cb;
252 _pool_2 $cb;
253 &schedule;
254 }
255 };
256
257 last if $@ eq "\3terminate\2\n";
258 warn $@ if $@;
259 }
260}
261
262sub async_pool(&@) {
263 # this is also inlined into the unlock_scheduler
264 my $coro = (pop @async_pool) || new Coro \&pool_handler;
265
266 $coro->{_invoke} = [@_];
267 $coro->ready;
268
269 $coro
169} 270}
170 271
171=item schedule 272=item schedule
172 273
173Calls the scheduler. Please note that the current process will not be put 274Calls the scheduler. Please note that the current coroutine will not be put
174into the ready queue, so calling this function usually means you will 275into the ready queue, so calling this function usually means you will
175never be called again. 276never be called again unless something else (e.g. an event handler) calls
277ready.
176 278
177=cut 279The canonical way to wait on external events is this:
280
281 {
282 # remember current coroutine
283 my $current = $Coro::current;
284
285 # register a hypothetical event handler
286 on_event_invoke sub {
287 # wake up sleeping coroutine
288 $current->ready;
289 undef $current;
290 };
291
292 # call schedule until event occurred.
293 # in case we are woken up for other reasons
294 # (current still defined), loop.
295 Coro::schedule while $current;
296 }
178 297
179=item cede 298=item cede
180 299
181"Cede" to other processes. This function puts the current process into the 300"Cede" to other coroutines. This function puts the current coroutine into the
182ready queue and calls C<schedule>, which has the effect of giving up the 301ready queue and calls C<schedule>, which has the effect of giving up the
183current "timeslice" to other coroutines of the same or higher priority. 302current "timeslice" to other coroutines of the same or higher priority.
184 303
185=cut 304Returns true if at least one coroutine switch has happened.
305
306=item Coro::cede_notself
307
308Works like cede, but is not exported by default and will cede to any
309coroutine, regardless of priority, once.
310
311Returns true if at least one coroutine switch has happened.
186 312
187=item terminate [arg...] 313=item terminate [arg...]
188 314
189Terminates the current process. 315Terminates the current coroutine with the given status values (see L<cancel>).
190
191Future versions of this function will allow result arguments.
192 316
193=cut 317=cut
194 318
195sub terminate { 319sub terminate {
196 $current->{status} = [@_];
197 $current->cancel; 320 $current->cancel (@_);
198 &schedule;
199 die; # NORETURN
200} 321}
201 322
202=back 323=back
203 324
204# dynamic methods 325# dynamic methods
205 326
206=head2 PROCESS METHODS 327=head2 COROUTINE METHODS
207 328
208These are the methods you can call on process objects. 329These are the methods you can call on coroutine objects.
209 330
210=over 4 331=over 4
211 332
212=item new Coro \&sub [, @args...] 333=item new Coro \&sub [, @args...]
213 334
214Create a new process and return it. When the sub returns the process 335Create a new coroutine and return it. When the sub returns the coroutine
215automatically terminates as if C<terminate> with the returned values were 336automatically terminates as if C<terminate> with the returned values were
216called. To make the process run you must first put it into the ready queue 337called. To make the coroutine run you must first put it into the ready queue
217by calling the ready method. 338by calling the ready method.
218 339
219=cut 340See C<async> for additional discussion.
220 341
342=cut
343
221sub _newcoro { 344sub _run_coro {
222 terminate &{+shift}; 345 terminate &{+shift};
223} 346}
224 347
225sub new { 348sub new {
226 my $class = shift; 349 my $class = shift;
227 bless {
228 _coro_state => (new Coro::State $_[0] && \&_newcoro, @_),
229 }, $class;
230}
231 350
232=item $process->ready 351 $class->SUPER::new (\&_run_coro, @_)
352}
233 353
234Put the given process into the ready queue. 354=item $success = $coroutine->ready
235 355
236=cut 356Put the given coroutine into the ready queue (according to it's priority)
357and return true. If the coroutine is already in the ready queue, do nothing
358and return false.
237 359
238=item $process->cancel 360=item $is_ready = $coroutine->is_ready
239 361
240Like C<terminate>, but terminates the specified process instead. 362Return wether the coroutine is currently the ready queue or not,
363
364=item $coroutine->cancel (arg...)
365
366Terminates the given coroutine and makes it return the given arguments as
367status (default: the empty list). Never returns if the coroutine is the
368current coroutine.
241 369
242=cut 370=cut
243 371
244sub cancel { 372sub cancel {
373 my $self = shift;
374 $self->{status} = [@_];
375
376 if ($current == $self) {
245 push @destroy, $_[0]; 377 push @destroy, $self;
246 $manager->ready; 378 $manager->ready;
247 &schedule if $current == $_[0]; 379 &schedule while 1;
380 } else {
381 $self->_cancel;
382 }
248} 383}
249 384
250=item $process->join 385=item $coroutine->join
251 386
252Wait until the coroutine terminates and return any values given to the 387Wait until the coroutine terminates and return any values given to the
253C<terminate> function. C<join> can be called multiple times from multiple 388C<terminate> or C<cancel> functions. C<join> can be called multiple times
254processes. 389from multiple coroutine.
255 390
256=cut 391=cut
257 392
258sub join { 393sub join {
259 my $self = shift; 394 my $self = shift;
395
260 unless ($self->{status}) { 396 unless ($self->{status}) {
261 push @{$self->{join}}, $current; 397 my $current = $current;
262 &schedule; 398
399 push @{$self->{destroy_cb}}, sub {
400 $current->ready;
401 undef $current;
402 };
403
404 &schedule while $current;
263 } 405 }
406
264 wantarray ? @{$self->{status}} : $self->{status}[0]; 407 wantarray ? @{$self->{status}} : $self->{status}[0];
265} 408}
266 409
410=item $coroutine->on_destroy (\&cb)
411
412Registers a callback that is called when this coroutine gets destroyed,
413but before it is joined. The callback gets passed the terminate arguments,
414if any.
415
416=cut
417
418sub on_destroy {
419 my ($self, $cb) = @_;
420
421 push @{ $self->{destroy_cb} }, $cb;
422}
423
267=item $oldprio = $process->prio($newprio) 424=item $oldprio = $coroutine->prio ($newprio)
268 425
269Sets (or gets, if the argument is missing) the priority of the 426Sets (or gets, if the argument is missing) the priority of the
270process. Higher priority processes get run before lower priority 427coroutine. Higher priority coroutines get run before lower priority
271processes. Priorities are small signed integers (currently -4 .. +3), 428coroutines. Priorities are small signed integers (currently -4 .. +3),
272that you can refer to using PRIO_xxx constants (use the import tag :prio 429that you can refer to using PRIO_xxx constants (use the import tag :prio
273to get then): 430to get then):
274 431
275 PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN 432 PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
276 3 > 1 > 0 > -1 > -3 > -4 433 3 > 1 > 0 > -1 > -3 > -4
279 current->prio(PRIO_HIGH); 436 current->prio(PRIO_HIGH);
280 437
281The idle coroutine ($Coro::idle) always has a lower priority than any 438The idle coroutine ($Coro::idle) always has a lower priority than any
282existing coroutine. 439existing coroutine.
283 440
284Changing the priority of the current process will take effect immediately, 441Changing the priority of the current coroutine will take effect immediately,
285but changing the priority of processes in the ready queue (but not 442but changing the priority of coroutines in the ready queue (but not
286running) will only take effect after the next schedule (of that 443running) will only take effect after the next schedule (of that
287process). This is a bug that will be fixed in some future version. 444coroutine). This is a bug that will be fixed in some future version.
288 445
289=cut
290
291sub prio {
292 my $old = $_[0]{prio};
293 $_[0]{prio} = $_[1] if @_ > 1;
294 $old;
295}
296
297=item $newprio = $process->nice($change) 446=item $newprio = $coroutine->nice ($change)
298 447
299Similar to C<prio>, but subtract the given value from the priority (i.e. 448Similar to C<prio>, but subtract the given value from the priority (i.e.
300higher values mean lower priority, just as in unix). 449higher values mean lower priority, just as in unix).
301 450
302=cut
303
304sub nice {
305 $_[0]{prio} -= $_[1];
306}
307
308=item $olddesc = $process->desc($newdesc) 451=item $olddesc = $coroutine->desc ($newdesc)
309 452
310Sets (or gets in case the argument is missing) the description for this 453Sets (or gets in case the argument is missing) the description for this
311process. This is just a free-form string you can associate with a process. 454coroutine. This is just a free-form string you can associate with a coroutine.
312 455
313=cut 456=cut
314 457
315sub desc { 458sub desc {
316 my $old = $_[0]{desc}; 459 my $old = $_[0]{desc};
318 $old; 461 $old;
319} 462}
320 463
321=back 464=back
322 465
466=head2 GLOBAL FUNCTIONS
467
468=over 4
469
470=item Coro::nready
471
472Returns the number of coroutines that are currently in the ready state,
473i.e. that can be switched to. The value C<0> means that the only runnable
474coroutine is the currently running one, so C<cede> would have no effect,
475and C<schedule> would cause a deadlock unless there is an idle handler
476that wakes up some coroutines.
477
478=item my $guard = Coro::guard { ... }
479
480This creates and returns a guard object. Nothing happens until the object
481gets destroyed, in which case the codeblock given as argument will be
482executed. This is useful to free locks or other resources in case of a
483runtime error or when the coroutine gets canceled, as in both cases the
484guard block will be executed. The guard object supports only one method,
485C<< ->cancel >>, which will keep the codeblock from being executed.
486
487Example: set some flag and clear it again when the coroutine gets canceled
488or the function returns:
489
490 sub do_something {
491 my $guard = Coro::guard { $busy = 0 };
492 $busy = 1;
493
494 # do something that requires $busy to be true
495 }
496
497=cut
498
499sub guard(&) {
500 bless \(my $cb = $_[0]), "Coro::guard"
501}
502
503sub Coro::guard::cancel {
504 ${$_[0]} = sub { };
505}
506
507sub Coro::guard::DESTROY {
508 ${$_[0]}->();
509}
510
511
512=item unblock_sub { ... }
513
514This utility function takes a BLOCK or code reference and "unblocks" it,
515returning the new coderef. This means that the new coderef will return
516immediately without blocking, returning nothing, while the original code
517ref will be called (with parameters) from within its own coroutine.
518
519The reason this function exists is that many event libraries (such as the
520venerable L<Event|Event> module) are not coroutine-safe (a weaker form
521of thread-safety). This means you must not block within event callbacks,
522otherwise you might suffer from crashes or worse.
523
524This function allows your callbacks to block by executing them in another
525coroutine where it is safe to block. One example where blocking is handy
526is when you use the L<Coro::AIO|Coro::AIO> functions to save results to
527disk.
528
529In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
530creating event callbacks that want to block.
531
532=cut
533
534our @unblock_queue;
535
536# we create a special coro because we want to cede,
537# to reduce pressure on the coro pool (because most callbacks
538# return immediately and can be reused) and because we cannot cede
539# inside an event callback.
540our $unblock_scheduler = new Coro sub {
541 while () {
542 while (my $cb = pop @unblock_queue) {
543 # this is an inlined copy of async_pool
544 my $coro = (pop @async_pool) || new Coro \&pool_handler;
545
546 $coro->{_invoke} = $cb;
547 $coro->ready;
548 cede; # for short-lived callbacks, this reduces pressure on the coro pool
549 }
550 schedule; # sleep well
551 }
552};
553$unblock_scheduler->desc ("[unblock_sub scheduler]");
554
555sub unblock_sub(&) {
556 my $cb = shift;
557
558 sub {
559 unshift @unblock_queue, [$cb, @_];
560 $unblock_scheduler->ready;
561 }
562}
563
564=back
565
323=cut 566=cut
324 567
3251; 5681;
326 569
327=head1 BUGS/LIMITATIONS 570=head1 BUGS/LIMITATIONS
328 571
329 - you must make very sure that no coro is still active on global 572 - you must make very sure that no coro is still active on global
330 destruction. very bad things might happen otherwise (usually segfaults). 573 destruction. very bad things might happen otherwise (usually segfaults).
331 574
332 - this module is not thread-safe. You should only ever use this module 575 - this module is not thread-safe. You should only ever use this module
333 from the same thread (this requirement might be losened in the future 576 from the same thread (this requirement might be loosened in the future
334 to allow per-thread schedulers, but Coro::State does not yet allow 577 to allow per-thread schedulers, but Coro::State does not yet allow
335 this). 578 this).
336 579
337=head1 SEE ALSO 580=head1 SEE ALSO
338 581
339L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>, 582Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.
340L<Coro::Signal>, L<Coro::State>, L<Coro::Timer>, L<Coro::Event>, 583
341L<Coro::L<Coro::RWLock>, Handle>, L<Coro::Socket>. 584Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
585
586Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.
587
588Embedding: L<Coro:MakeMaker>
342 589
343=head1 AUTHOR 590=head1 AUTHOR
344 591
345 Marc Lehmann <pcg@goof.com> 592 Marc Lehmann <schmorp@schmorp.de>
346 http://www.goof.com/pcg/marc/ 593 http://home.schmorp.de/
347 594
348=cut 595=cut
349 596

Diff Legend

Removed lines
+ Added lines
< Changed lines
> Changed lines