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Revision 1.102 by root, Fri Dec 29 11:37:49 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
244 316
245=item terminate [arg...] 317=item terminate [arg...]
246 318
247Terminates the current coroutine with the given status values (see L<cancel>). 319Terminates the current coroutine with the given status values (see L<cancel>).
248 320
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.
326
249=cut 327=cut
250 328
251sub terminate { 329sub terminate {
252 $current->cancel (@_); 330 $current->cancel (@_);
253} 331}
254 332
333sub killall {
334 for (Coro::State::list) {
335 $_->cancel
336 if $_ != $current && UNIVERSAL::isa $_, "Coro";
337 }
338}
339
255=back 340=back
256
257# dynamic methods
258 341
259=head2 COROUTINE METHODS 342=head2 COROUTINE METHODS
260 343
261These are the methods you can call on coroutine objects. 344These are the methods you can call on coroutine objects.
262 345
267Create 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
268automatically terminates as if C<terminate> with the returned values were 351automatically terminates as if C<terminate> with the returned values were
269called. 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
270by calling the ready method. 353by calling the ready method.
271 354
272Calling 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.
273 357
274=cut 358=cut
275 359
276sub _run_coro { 360sub _run_coro {
277 terminate &{+shift}; 361 terminate &{+shift};
294Return wether the coroutine is currently the ready queue or not, 378Return wether the coroutine is currently the ready queue or not,
295 379
296=item $coroutine->cancel (arg...) 380=item $coroutine->cancel (arg...)
297 381
298Terminates the given coroutine and makes it return the given arguments as 382Terminates the given coroutine and makes it return the given arguments as
299status (default: the empty list). 383status (default: the empty list). Never returns if the coroutine is the
384current coroutine.
300 385
301=cut 386=cut
302 387
303sub cancel { 388sub cancel {
304 my $self = shift; 389 my $self = shift;
305 $self->{status} = [@_]; 390 $self->{_status} = [@_];
391
392 if ($current == $self) {
306 push @destroy, $self; 393 push @destroy, $self;
307 $manager->ready; 394 $manager->ready;
308 &schedule if $current == $self; 395 &schedule while 1;
396 } else {
397 $self->_cancel;
398 }
309} 399}
310 400
311=item $coroutine->join 401=item $coroutine->join
312 402
313Wait until the coroutine terminates and return any values given to the 403Wait until the coroutine terminates and return any values given to the
314C<terminate> or C<cancel> functions. C<join> can be called multiple times 404C<terminate> or C<cancel> functions. C<join> can be called concurrently
315from multiple coroutine. 405from multiple coroutines.
316 406
317=cut 407=cut
318 408
319sub join { 409sub join {
320 my $self = shift; 410 my $self = shift;
411
321 unless ($self->{status}) { 412 unless ($self->{_status}) {
322 push @{$self->{join}}, $current; 413 my $current = $current;
323 &schedule; 414
415 push @{$self->{_on_destroy}}, sub {
416 $current->ready;
417 undef $current;
418 };
419
420 &schedule while $current;
324 } 421 }
422
325 wantarray ? @{$self->{status}} : $self->{status}[0]; 423 wantarray ? @{$self->{_status}} : $self->{_status}[0];
326} 424}
327 425
328=item $coroutine->on_destroy (\&cb) 426=item $coroutine->on_destroy (\&cb)
329 427
330Registers a callback that is called when this coroutine gets destroyed, 428Registers a callback that is called when this coroutine gets destroyed,
334=cut 432=cut
335 433
336sub on_destroy { 434sub on_destroy {
337 my ($self, $cb) = @_; 435 my ($self, $cb) = @_;
338 436
339 push @{ $self->{destroy_cb} }, $cb; 437 push @{ $self->{_on_destroy} }, $cb;
340} 438}
341 439
342=item $oldprio = $coroutine->prio ($newprio) 440=item $oldprio = $coroutine->prio ($newprio)
343 441
344Sets (or gets, if the argument is missing) the priority of the 442Sets (or gets, if the argument is missing) the priority of the
369=item $olddesc = $coroutine->desc ($newdesc) 467=item $olddesc = $coroutine->desc ($newdesc)
370 468
371Sets (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
372coroutine. 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.
373 471
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
374=cut 491=cut
375 492
376sub desc { 493sub desc {
377 my $old = $_[0]{desc}; 494 my $old = $_[0]{desc};
378 $_[0]{desc} = $_[1] if @_ > 1; 495 $_[0]{desc} = $_[1] if @_ > 1;
386=over 4 503=over 4
387 504
388=item Coro::nready 505=item Coro::nready
389 506
390Returns the number of coroutines that are currently in the ready state, 507Returns the number of coroutines that are currently in the ready state,
391i.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
392coroutine 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,
393and 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
394that 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
395 546
396=item unblock_sub { ... } 547=item unblock_sub { ... }
397 548
398This utility function takes a BLOCK or code reference and "unblocks" it, 549This utility function takes a BLOCK or code reference and "unblocks" it,
399returning the new coderef. This means that the new coderef will return 550returning the new coderef. This means that the new coderef will return
400immediately without blocking, returning nothing, while the original code 551immediately without blocking, returning nothing, while the original code
401ref will be called (with parameters) from within its own coroutine. 552ref will be called (with parameters) from within its own coroutine.
402 553
403The 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
404venerable L<Event|Event> module) are not coroutine-safe (a weaker form 555venerable L<Event|Event> module) are not coroutine-safe (a weaker form
405of thread-safety). This means you must not block within event callbacks, 556of thread-safety). This means you must not block within event callbacks,
406otherwise you might suffer from crashes or worse. 557otherwise you might suffer from crashes or worse.
407 558
408This function allows your callbacks to block by executing them in another 559This function allows your callbacks to block by executing them in another
413In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when 564In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
414creating event callbacks that want to block. 565creating event callbacks that want to block.
415 566
416=cut 567=cut
417 568
418our @unblock_pool;
419our @unblock_queue; 569our @unblock_queue;
420our $UNBLOCK_POOL_SIZE = 2;
421 570
422sub unblock_handler_ { 571# we create a special coro because we want to cede,
423 while () { 572# to reduce pressure on the coro pool (because most callbacks
424 my ($cb, @arg) = @{ delete $Coro::current->{arg} }; 573# return immediately and can be reused) and because we cannot cede
425 $cb->(@arg); 574# inside an event callback.
426
427 last if @unblock_pool >= $UNBLOCK_POOL_SIZE;
428 push @unblock_pool, $Coro::current;
429 schedule;
430 }
431}
432
433our $unblock_scheduler = async { 575our $unblock_scheduler = new Coro sub {
434 while () { 576 while () {
435 while (my $cb = pop @unblock_queue) { 577 while (my $cb = pop @unblock_queue) {
436 my $handler = (pop @unblock_pool or new Coro \&unblock_handler_); 578 # this is an inlined copy of async_pool
437 $handler->{arg} = $cb; 579 my $coro = (pop @async_pool) || new Coro \&pool_handler;
580
581 $coro->{_invoke} = $cb;
438 $handler->ready; 582 $coro->ready;
439 cede; 583 cede; # for short-lived callbacks, this reduces pressure on the coro pool
440 } 584 }
441 585 schedule; # sleep well
442 schedule;
443 } 586 }
444}; 587};
588$unblock_scheduler->desc ("[unblock_sub scheduler]");
445 589
446sub unblock_sub(&) { 590sub unblock_sub(&) {
447 my $cb = shift; 591 my $cb = shift;
448 592
449 sub { 593 sub {
450 push @unblock_queue, [$cb, @_]; 594 unshift @unblock_queue, [$cb, @_];
451 $unblock_scheduler->ready; 595 $unblock_scheduler->ready;
452 } 596 }
453} 597}
454 598
455=back 599=back
462 606
463 - 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
464 destruction. very bad things might happen otherwise (usually segfaults). 608 destruction. very bad things might happen otherwise (usually segfaults).
465 609
466 - 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
467 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
468 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
469 this). 613 this).
470 614
471=head1 SEE ALSO 615=head1 SEE ALSO
472 616
617Lower level Configuration, Coroutine Environment: L<Coro::State>.
618
619Debugging: L<Coro::Debug>.
620
473Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>. 621Support/Utility: L<Coro::Specific>, L<Coro::Util>.
474 622
475Locking/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>.
476 624
477Event/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>.
478 626
627Compatibility: L<Coro::LWP>, L<Coro::Storable>, L<Coro::Select>.
628
479Embedding: L<Coro:MakeMaker> 629Embedding: L<Coro::MakeMaker>.
480 630
481=head1 AUTHOR 631=head1 AUTHOR
482 632
483 Marc Lehmann <schmorp@schmorp.de> 633 Marc Lehmann <schmorp@schmorp.de>
484 http://home.schmorp.de/ 634 http://home.schmorp.de/

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