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Revision 1.101 by root, Fri Dec 29 08:36:34 2006 UTC vs.
Revision 1.178 by root, Thu Apr 17 22:33:10 2008 UTC

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 };
15 print "1\n";
16 cede; # yield to coroutine
17 print "3\n";
18 cede; # and again
12 19
13 # alternatively create an async coroutine like this: 20 # use locking
21 my $lock = new Coro::Semaphore;
22 my $locked;
14 23
15 sub some_func : Coro { 24 $lock->down;
16 # some more async code 25 $locked = 1;
17 } 26 $lock->up;
18
19 cede;
20 27
21=head1 DESCRIPTION 28=head1 DESCRIPTION
22 29
23This module collection manages coroutines. Coroutines are similar 30This module collection manages coroutines. Coroutines are similar
24to threads but don't run in parallel at the same time even on SMP 31to threads but don't run in parallel at the same time even on SMP
25machines. The specific flavor of coroutine use din this module also 32machines. The specific flavor of coroutine used in this module also
26guarentees you that it will not switch between coroutines unless 33guarantees you that it will not switch between coroutines unless
27necessary, at easily-identified points in your program, so locking and 34necessary, at easily-identified points in your program, so locking and
28parallel access are rarely an issue, making coroutine programming much 35parallel access are rarely an issue, making coroutine programming much
29safer than threads programming. 36safer than threads programming.
30 37
31(Perl, however, does not natively support real threads but instead does a 38(Perl, however, does not natively support real threads but instead does a
33is a performance win on Windows machines, and a loss everywhere else). 40is a performance win on Windows machines, and a loss everywhere else).
34 41
35In this module, coroutines are defined as "callchain + lexical variables + 42In this module, coroutines are defined as "callchain + lexical variables +
36@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain, 43@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,
37its own set of lexicals and its own set of perls most important global 44its own set of lexicals and its own set of perls most important global
38variables. 45variables (see L<Coro::State> for more configuration).
39 46
40=cut 47=cut
41 48
42package Coro; 49package Coro;
43 50
50 57
51our $idle; # idle handler 58our $idle; # idle handler
52our $main; # main coroutine 59our $main; # main coroutine
53our $current; # current coroutine 60our $current; # current coroutine
54 61
55our $VERSION = '3.3'; 62our $VERSION = '4.51';
56 63
57our @EXPORT = qw(async cede schedule terminate current unblock_sub); 64our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
58our %EXPORT_TAGS = ( 65our %EXPORT_TAGS = (
59 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], 66 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
60); 67);
61our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready)); 68our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
62 69
108 115
109The current coroutine (the last coroutine switched to). The initial value 116The current coroutine (the last coroutine switched to). The initial value
110is C<$main> (of course). 117is C<$main> (of course).
111 118
112This variable is B<strictly> I<read-only>. It is provided for performance 119This variable is B<strictly> I<read-only>. It is provided for performance
113reasons. If performance is not essentiel you are encouraged to use the 120reasons. If performance is not essential you are encouraged to use the
114C<Coro::current> function instead. 121C<Coro::current> function instead.
115 122
116=cut 123=cut
117 124
125$main->{desc} = "[main::]";
126
118# maybe some other module used Coro::Specific before... 127# maybe some other module used Coro::Specific before...
119$main->{specific} = $current->{specific} 128$main->{_specific} = $current->{_specific}
120 if $current; 129 if $current;
121 130
122_set_current $main; 131_set_current $main;
123 132
124sub current() { $current } 133sub current() { $current }
132This hook is overwritten by modules such as C<Coro::Timer> and 141This hook is overwritten by modules such as C<Coro::Timer> and
133C<Coro::Event> to wait on an external event that hopefully wake up a 142C<Coro::Event> to wait on an external event that hopefully wake up a
134coroutine so the scheduler can run it. 143coroutine so the scheduler can run it.
135 144
136Please note that if your callback recursively invokes perl (e.g. for event 145Please note that if your callback recursively invokes perl (e.g. for event
137handlers), then it must be prepared to be called recursively. 146handlers), then it must be prepared to be called recursively itself.
138 147
139=cut 148=cut
140 149
141$idle = sub { 150$idle = sub {
142 require Carp; 151 require Carp;
143 Carp::croak ("FATAL: deadlock detected"); 152 Carp::croak ("FATAL: deadlock detected");
144}; 153};
145 154
155sub _cancel {
156 my ($self) = @_;
157
158 # free coroutine data and mark as destructed
159 $self->_destroy
160 or return;
161
162 # call all destruction callbacks
163 $_->(@{$self->{_status}})
164 for @{(delete $self->{_on_destroy}) || []};
165}
166
146# this coroutine is necessary because a coroutine 167# this coroutine is necessary because a coroutine
147# cannot destroy itself. 168# cannot destroy itself.
148my @destroy; 169my @destroy;
170my $manager;
171
149my $manager; $manager = new Coro sub { 172$manager = new Coro sub {
150 while () { 173 while () {
151 # by overwriting the state object with the manager we destroy it 174 (shift @destroy)->_cancel
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) { 175 while @destroy;
157 my $coro = pop @destroy;
158 176
159 $coro->{status} ||= [];
160
161 $_->ready for @{(delete $coro->{join} ) || []};
162 $_->(@{$coro->{status}}) for @{(delete $coro->{destroy_cb}) || []};
163
164 # the next line destroys the coro state, but keeps the
165 # coroutine itself intact (we basically make it a zombie
166 # coroutine that always runs the manager thread, so it's possible
167 # to transfer() to this coroutine).
168 $coro->_clone_state_from ($manager);
169 }
170 &schedule; 177 &schedule;
171 } 178 }
172}; 179};
173 180$manager->desc ("[coro manager]");
174# static methods. not really. 181$manager->prio (PRIO_MAX);
175 182
176=back 183=back
177 184
178=head2 STATIC METHODS 185=head2 STATIC METHODS
179 186
185 192
186Create a new asynchronous coroutine and return it's coroutine object 193Create a new asynchronous coroutine and return it's coroutine object
187(usually unused). When the sub returns the new coroutine is automatically 194(usually unused). When the sub returns the new coroutine is automatically
188terminated. 195terminated.
189 196
190Calling C<exit> in a coroutine will not work correctly, so do not do that. 197See the C<Coro::State::new> constructor for info about the coroutine
198environment in which coroutines run.
191 199
192When the coroutine dies, the program will exit, just as in the main 200Calling C<exit> in a coroutine will do the same as calling exit outside
193program. 201the coroutine. Likewise, when the coroutine dies, the program will exit,
202just as it would in the main program.
194 203
195 # create a new coroutine that just prints its arguments 204 # create a new coroutine that just prints its arguments
196 async { 205 async {
197 print "@_\n"; 206 print "@_\n";
198 } 1,2,3,4; 207 } 1,2,3,4;
199 208
200=cut 209=cut
201 210
202sub async(&@) { 211sub async(&@) {
203 my $pid = new Coro @_; 212 my $coro = new Coro @_;
204 $pid->ready; 213 $coro->ready;
205 $pid 214 $coro
215}
216
217=item async_pool { ... } [@args...]
218
219Similar to C<async>, but uses a coroutine pool, so you should not call
220terminate or join (although you are allowed to), and you get a coroutine
221that might have executed other code already (which can be good or bad :).
222
223Also, the block is executed in an C<eval> context and a warning will be
224issued in case of an exception instead of terminating the program, as
225C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
226will not work in the expected way, unless you call terminate or cancel,
227which somehow defeats the purpose of pooling.
228
229The priority will be reset to C<0> after each job, tracing will be
230disabled, the description will be reset and the default output filehandle
231gets restored, so you can change alkl these. Otherwise the coroutine will
232be re-used "as-is": most notably if you change other per-coroutine global
233stuff such as C<$/> you need to revert that change, which is most simply
234done by using local as in C< local $/ >.
235
236The pool size is limited to 8 idle coroutines (this can be adjusted by
237changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
238required.
239
240If you are concerned about pooled coroutines growing a lot because a
241single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
242{ terminate }> once per second or so to slowly replenish the pool. In
243addition to that, when the stacks used by a handler grows larger than 16kb
244(adjustable with $Coro::POOL_RSS) it will also exit.
245
246=cut
247
248our $POOL_SIZE = 8;
249our $POOL_RSS = 16 * 1024;
250our @async_pool;
251
252sub pool_handler {
253 my $cb;
254
255 while () {
256 eval {
257 while () {
258 _pool_1 $cb;
259 &$cb;
260 _pool_2 $cb;
261 &schedule;
262 }
263 };
264
265 last if $@ eq "\3async_pool terminate\2\n";
266 warn $@ if $@;
267 }
268}
269
270sub async_pool(&@) {
271 # this is also inlined into the unlock_scheduler
272 my $coro = (pop @async_pool) || new Coro \&pool_handler;
273
274 $coro->{_invoke} = [@_];
275 $coro->ready;
276
277 $coro
206} 278}
207 279
208=item schedule 280=item schedule
209 281
210Calls the scheduler. Please note that the current coroutine will not be put 282Calls the scheduler. Please note that the current coroutine will not be put
223 # wake up sleeping coroutine 295 # wake up sleeping coroutine
224 $current->ready; 296 $current->ready;
225 undef $current; 297 undef $current;
226 }; 298 };
227 299
228 # call schedule until event occured. 300 # call schedule until event occurred.
229 # in case we are woken up for other reasons 301 # in case we are woken up for other reasons
230 # (current still defined), loop. 302 # (current still defined), loop.
231 Coro::schedule while $current; 303 Coro::schedule while $current;
232 } 304 }
233 305
235 307
236"Cede" to other coroutines. This function puts the current coroutine into the 308"Cede" to other coroutines. This function puts the current coroutine into the
237ready queue and calls C<schedule>, which has the effect of giving up the 309ready queue and calls C<schedule>, which has the effect of giving up the
238current "timeslice" to other coroutines of the same or higher priority. 310current "timeslice" to other coroutines of the same or higher priority.
239 311
312=item Coro::cede_notself
313
314Works like cede, but is not exported by default and will cede to any
315coroutine, regardless of priority, once.
316
240=item terminate [arg...] 317=item terminate [arg...]
241 318
242Terminates the current coroutine with the given status values (see L<cancel>). 319Terminates the current coroutine with the given status values (see L<cancel>).
320
321=item killall
322
323Kills/terminates/cancels all coroutines except the currently running
324one. This is useful after a fork, either in the child or the parent, as
325usually only one of them should inherit the running coroutines.
243 326
244=cut 327=cut
245 328
246sub terminate { 329sub terminate {
247 $current->cancel (@_); 330 $current->cancel (@_);
248} 331}
249 332
333sub killall {
334 for (Coro::State::list) {
335 $_->cancel
336 if $_ != $current && UNIVERSAL::isa $_, "Coro";
337 }
338}
339
250=back 340=back
251
252# dynamic methods
253 341
254=head2 COROUTINE METHODS 342=head2 COROUTINE METHODS
255 343
256These are the methods you can call on coroutine objects. 344These are the methods you can call on coroutine objects.
257 345
262Create a new coroutine and return it. When the sub returns the coroutine 350Create a new coroutine and return it. When the sub returns the coroutine
263automatically terminates as if C<terminate> with the returned values were 351automatically terminates as if C<terminate> with the returned values were
264called. To make the coroutine run you must first put it into the ready queue 352called. To make the coroutine run you must first put it into the ready queue
265by calling the ready method. 353by calling the ready method.
266 354
267Calling C<exit> in a coroutine will not work correctly, so do not do that. 355See C<async> and C<Coro::State::new> for additional info about the
356coroutine environment.
268 357
269=cut 358=cut
270 359
271sub _run_coro { 360sub _run_coro {
272 terminate &{+shift}; 361 terminate &{+shift};
289Return wether the coroutine is currently the ready queue or not, 378Return wether the coroutine is currently the ready queue or not,
290 379
291=item $coroutine->cancel (arg...) 380=item $coroutine->cancel (arg...)
292 381
293Terminates the given coroutine and makes it return the given arguments as 382Terminates the given coroutine and makes it return the given arguments as
294status (default: the empty list). 383status (default: the empty list). Never returns if the coroutine is the
384current coroutine.
295 385
296=cut 386=cut
297 387
298sub cancel { 388sub cancel {
299 my $self = shift; 389 my $self = shift;
300 $self->{status} = [@_]; 390 $self->{_status} = [@_];
391
392 if ($current == $self) {
301 push @destroy, $self; 393 push @destroy, $self;
302 $manager->ready; 394 $manager->ready;
303 &schedule if $current == $self; 395 &schedule while 1;
396 } else {
397 $self->_cancel;
398 }
304} 399}
305 400
306=item $coroutine->join 401=item $coroutine->join
307 402
308Wait until the coroutine terminates and return any values given to the 403Wait until the coroutine terminates and return any values given to the
309C<terminate> or C<cancel> functions. C<join> can be called multiple times 404C<terminate> or C<cancel> functions. C<join> can be called concurrently
310from multiple coroutine. 405from multiple coroutines.
311 406
312=cut 407=cut
313 408
314sub join { 409sub join {
315 my $self = shift; 410 my $self = shift;
411
316 unless ($self->{status}) { 412 unless ($self->{_status}) {
317 push @{$self->{join}}, $current; 413 my $current = $current;
318 &schedule; 414
415 push @{$self->{_on_destroy}}, sub {
416 $current->ready;
417 undef $current;
418 };
419
420 &schedule while $current;
319 } 421 }
422
320 wantarray ? @{$self->{status}} : $self->{status}[0]; 423 wantarray ? @{$self->{_status}} : $self->{_status}[0];
321} 424}
322 425
323=item $coroutine->on_destroy (\&cb) 426=item $coroutine->on_destroy (\&cb)
324 427
325Registers a callback that is called when this coroutine gets destroyed, 428Registers a callback that is called when this coroutine gets destroyed,
329=cut 432=cut
330 433
331sub on_destroy { 434sub on_destroy {
332 my ($self, $cb) = @_; 435 my ($self, $cb) = @_;
333 436
334 push @{ $self->{destroy_cb} }, $cb; 437 push @{ $self->{_on_destroy} }, $cb;
335} 438}
336 439
337=item $oldprio = $coroutine->prio ($newprio) 440=item $oldprio = $coroutine->prio ($newprio)
338 441
339Sets (or gets, if the argument is missing) the priority of the 442Sets (or gets, if the argument is missing) the priority of the
364=item $olddesc = $coroutine->desc ($newdesc) 467=item $olddesc = $coroutine->desc ($newdesc)
365 468
366Sets (or gets in case the argument is missing) the description for this 469Sets (or gets in case the argument is missing) the description for this
367coroutine. This is just a free-form string you can associate with a coroutine. 470coroutine. This is just a free-form string you can associate with a coroutine.
368 471
472This method simply sets the C<< $coroutine->{desc} >> member to the given string. You
473can modify this member directly if you wish.
474
475=item $coroutine->throw ([$scalar])
476
477If C<$throw> is specified and defined, it will be thrown as an exception
478inside the coroutine at the next convinient point in time (usually after
479it gains control at the next schedule/transfer/cede). Otherwise clears the
480exception object.
481
482The exception object will be thrown "as is" with the specified scalar in
483C<$@>, i.e. if it is a string, no line number or newline will be appended
484(unlike with C<die>).
485
486This can be used as a softer means than C<cancel> to ask a coroutine to
487end itself, although there is no guarentee that the exception will lead to
488termination, and if the exception isn't caught it might well end the whole
489program.
490
369=cut 491=cut
370 492
371sub desc { 493sub desc {
372 my $old = $_[0]{desc}; 494 my $old = $_[0]{desc};
373 $_[0]{desc} = $_[1] if @_ > 1; 495 $_[0]{desc} = $_[1] if @_ > 1;
381=over 4 503=over 4
382 504
383=item Coro::nready 505=item Coro::nready
384 506
385Returns the number of coroutines that are currently in the ready state, 507Returns the number of coroutines that are currently in the ready state,
386i.e. that can be swicthed to. The value C<0> means that the only runnable 508i.e. that can be switched to. The value C<0> means that the only runnable
387coroutine is the currently running one, so C<cede> would have no effect, 509coroutine is the currently running one, so C<cede> would have no effect,
388and C<schedule> would cause a deadlock unless there is an idle handler 510and C<schedule> would cause a deadlock unless there is an idle handler
389that wakes up some coroutines. 511that wakes up some coroutines.
512
513=item my $guard = Coro::guard { ... }
514
515This creates and returns a guard object. Nothing happens until the object
516gets destroyed, in which case the codeblock given as argument will be
517executed. This is useful to free locks or other resources in case of a
518runtime error or when the coroutine gets canceled, as in both cases the
519guard block will be executed. The guard object supports only one method,
520C<< ->cancel >>, which will keep the codeblock from being executed.
521
522Example: set some flag and clear it again when the coroutine gets canceled
523or the function returns:
524
525 sub do_something {
526 my $guard = Coro::guard { $busy = 0 };
527 $busy = 1;
528
529 # do something that requires $busy to be true
530 }
531
532=cut
533
534sub guard(&) {
535 bless \(my $cb = $_[0]), "Coro::guard"
536}
537
538sub Coro::guard::cancel {
539 ${$_[0]} = sub { };
540}
541
542sub Coro::guard::DESTROY {
543 ${$_[0]}->();
544}
545
390 546
391=item unblock_sub { ... } 547=item unblock_sub { ... }
392 548
393This utility function takes a BLOCK or code reference and "unblocks" it, 549This utility function takes a BLOCK or code reference and "unblocks" it,
394returning the new coderef. This means that the new coderef will return 550returning the new coderef. This means that the new coderef will return
395immediately without blocking, returning nothing, while the original code 551immediately without blocking, returning nothing, while the original code
396ref will be called (with parameters) from within its own coroutine. 552ref will be called (with parameters) from within its own coroutine.
397 553
398The reason this fucntion exists is that many event libraries (such as the 554The reason this function exists is that many event libraries (such as the
399venerable L<Event|Event> module) are not coroutine-safe (a weaker form 555venerable L<Event|Event> module) are not coroutine-safe (a weaker form
400of thread-safety). This means you must not block within event callbacks, 556of thread-safety). This means you must not block within event callbacks,
401otherwise you might suffer from crashes or worse. 557otherwise you might suffer from crashes or worse.
402 558
403This function allows your callbacks to block by executing them in another 559This function allows your callbacks to block by executing them in another
408In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when 564In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
409creating event callbacks that want to block. 565creating event callbacks that want to block.
410 566
411=cut 567=cut
412 568
413our @unblock_pool;
414our @unblock_queue; 569our @unblock_queue;
415our $UNBLOCK_POOL_SIZE = 2;
416 570
417sub unblock_handler_ { 571# we create a special coro because we want to cede,
418 while () { 572# to reduce pressure on the coro pool (because most callbacks
419 my ($cb, @arg) = @{ delete $Coro::current->{arg} }; 573# return immediately and can be reused) and because we cannot cede
420 $cb->(@arg); 574# inside an event callback.
421
422 last if @unblock_pool >= $UNBLOCK_POOL_SIZE;
423 push @unblock_pool, $Coro::current;
424 schedule;
425 }
426}
427
428our $unblock_scheduler = async { 575our $unblock_scheduler = new Coro sub {
429 while () { 576 while () {
430 while (my $cb = pop @unblock_queue) { 577 while (my $cb = pop @unblock_queue) {
431 my $handler = (pop @unblock_pool or new Coro \&unblock_handler_); 578 # this is an inlined copy of async_pool
432 $handler->{arg} = $cb; 579 my $coro = (pop @async_pool) || new Coro \&pool_handler;
580
581 $coro->{_invoke} = $cb;
433 $handler->ready; 582 $coro->ready;
434 cede; 583 cede; # for short-lived callbacks, this reduces pressure on the coro pool
435 } 584 }
436 585 schedule; # sleep well
437 schedule;
438 } 586 }
439}; 587};
588$unblock_scheduler->desc ("[unblock_sub scheduler]");
440 589
441sub unblock_sub(&) { 590sub unblock_sub(&) {
442 my $cb = shift; 591 my $cb = shift;
443 592
444 sub { 593 sub {
445 push @unblock_queue, [$cb, @_]; 594 unshift @unblock_queue, [$cb, @_];
446 $unblock_scheduler->ready; 595 $unblock_scheduler->ready;
447 } 596 }
448} 597}
449 598
450=back 599=back
457 606
458 - you must make very sure that no coro is still active on global 607 - you must make very sure that no coro is still active on global
459 destruction. very bad things might happen otherwise (usually segfaults). 608 destruction. very bad things might happen otherwise (usually segfaults).
460 609
461 - this module is not thread-safe. You should only ever use this module 610 - this module is not thread-safe. You should only ever use this module
462 from the same thread (this requirement might be losened in the future 611 from the same thread (this requirement might be loosened in the future
463 to allow per-thread schedulers, but Coro::State does not yet allow 612 to allow per-thread schedulers, but Coro::State does not yet allow
464 this). 613 this).
465 614
466=head1 SEE ALSO 615=head1 SEE ALSO
467 616
617Lower level Configuration, Coroutine Environment: L<Coro::State>.
618
619Debugging: L<Coro::Debug>.
620
468Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>. 621Support/Utility: L<Coro::Specific>, L<Coro::Util>.
469 622
470Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>. 623Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
471 624
472Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>. 625Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>.
473 626
627Compatibility: L<Coro::LWP>, L<Coro::Storable>, L<Coro::Select>.
628
474Embedding: L<Coro:MakeMaker> 629Embedding: L<Coro::MakeMaker>.
475 630
476=head1 AUTHOR 631=head1 AUTHOR
477 632
478 Marc Lehmann <schmorp@schmorp.de> 633 Marc Lehmann <schmorp@schmorp.de>
479 http://home.schmorp.de/ 634 http://home.schmorp.de/

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