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Revision 1.100 by root, Tue Dec 12 13:56:45 2006 UTC vs.
Revision 1.175 by root, Sun Apr 6 19:23:50 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 = '3.2'; 62our $VERSION = '4.49';
56 63
57our @EXPORT = qw(async cede schedule terminate current unblock_sub); 64our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
58our %EXPORT_TAGS = ( 65our %EXPORT_TAGS = (
59 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], 66 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
60); 67);
61our @EXPORT_OK = (@{$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 $coro->{status} ||= [];
159 $_->ready for @{delete $coro->{join} || []};
160 176
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; 177 &schedule;
168 } 178 }
169}; 179};
180$manager->desc ("[coro manager]");
181$manager->prio (PRIO_MAX);
170 182
171# static methods. not really. 183# static methods. not really.
172 184
173=back 185=back
174 186
182 194
183Create a new asynchronous coroutine and return it's coroutine object 195Create a new asynchronous coroutine and return it's coroutine object
184(usually unused). When the sub returns the new coroutine is automatically 196(usually unused). When the sub returns the new coroutine is automatically
185terminated. 197terminated.
186 198
187Calling C<exit> in a coroutine will not work correctly, so do not do that. 199See the C<Coro::State::new> constructor for info about the coroutine
200environment in which coroutines run.
188 201
189When the coroutine dies, the program will exit, just as in the main 202Calling C<exit> in a coroutine will do the same as calling exit outside
190program. 203the coroutine. Likewise, when the coroutine dies, the program will exit,
204just as it would in the main program.
191 205
192 # create a new coroutine that just prints its arguments 206 # create a new coroutine that just prints its arguments
193 async { 207 async {
194 print "@_\n"; 208 print "@_\n";
195 } 1,2,3,4; 209 } 1,2,3,4;
196 210
197=cut 211=cut
198 212
199sub async(&@) { 213sub async(&@) {
200 my $pid = new Coro @_; 214 my $coro = new Coro @_;
201 $pid->ready; 215 $coro->ready;
202 $pid 216 $coro
217}
218
219=item async_pool { ... } [@args...]
220
221Similar to C<async>, but uses a coroutine pool, so you should not call
222terminate or join (although you are allowed to), and you get a coroutine
223that might have executed other code already (which can be good or bad :).
224
225Also, the block is executed in an C<eval> context and a warning will be
226issued in case of an exception instead of terminating the program, as
227C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
228will not work in the expected way, unless you call terminate or cancel,
229which somehow defeats the purpose of pooling.
230
231The priority will be reset to C<0> after each job, tracing will be
232disabled, the description will be reset and the default output filehandle
233gets restored, so you can change alkl these. Otherwise the coroutine will
234be re-used "as-is": most notably if you change other per-coroutine global
235stuff such as C<$/> you need to revert that change, which is most simply
236done by using local as in C< local $/ >.
237
238The pool size is limited to 8 idle coroutines (this can be adjusted by
239changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
240required.
241
242If you are concerned about pooled coroutines growing a lot because a
243single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
244{ terminate }> once per second or so to slowly replenish the pool. In
245addition to that, when the stacks used by a handler grows larger than 16kb
246(adjustable with $Coro::POOL_RSS) it will also exit.
247
248=cut
249
250our $POOL_SIZE = 8;
251our $POOL_RSS = 16 * 1024;
252our @async_pool;
253
254sub pool_handler {
255 my $cb;
256
257 while () {
258 eval {
259 while () {
260 _pool_1 $cb;
261 &$cb;
262 _pool_2 $cb;
263 &schedule;
264 }
265 };
266
267 last if $@ eq "\3async_pool terminate\2\n";
268 warn $@ if $@;
269 }
270}
271
272sub async_pool(&@) {
273 # this is also inlined into the unlock_scheduler
274 my $coro = (pop @async_pool) || new Coro \&pool_handler;
275
276 $coro->{_invoke} = [@_];
277 $coro->ready;
278
279 $coro
203} 280}
204 281
205=item schedule 282=item schedule
206 283
207Calls the scheduler. Please note that the current coroutine will not be put 284Calls the scheduler. Please note that the current coroutine will not be put
220 # wake up sleeping coroutine 297 # wake up sleeping coroutine
221 $current->ready; 298 $current->ready;
222 undef $current; 299 undef $current;
223 }; 300 };
224 301
225 # call schedule until event occured. 302 # call schedule until event occurred.
226 # in case we are woken up for other reasons 303 # in case we are woken up for other reasons
227 # (current still defined), loop. 304 # (current still defined), loop.
228 Coro::schedule while $current; 305 Coro::schedule while $current;
229 } 306 }
230 307
232 309
233"Cede" to other coroutines. This function puts the current coroutine into the 310"Cede" to other coroutines. This function puts the current coroutine into the
234ready queue and calls C<schedule>, which has the effect of giving up the 311ready queue and calls C<schedule>, which has the effect of giving up the
235current "timeslice" to other coroutines of the same or higher priority. 312current "timeslice" to other coroutines of the same or higher priority.
236 313
314=item Coro::cede_notself
315
316Works like cede, but is not exported by default and will cede to any
317coroutine, regardless of priority, once.
318
237=item terminate [arg...] 319=item terminate [arg...]
238 320
239Terminates the current coroutine with the given status values (see L<cancel>). 321Terminates the current coroutine with the given status values (see L<cancel>).
322
323=item killall
324
325Kills/terminates/cancels all coroutines except the currently running
326one. This is useful after a fork, either in the child or the parent, as
327usually only one of them should inherit the running coroutines.
240 328
241=cut 329=cut
242 330
243sub terminate { 331sub terminate {
244 $current->cancel (@_); 332 $current->cancel (@_);
333}
334
335sub killall {
336 for (Coro::State::list) {
337 $_->cancel
338 if $_ != $current && UNIVERSAL::isa $_, "Coro";
339 }
245} 340}
246 341
247=back 342=back
248 343
249# dynamic methods 344# dynamic methods
259Create a new coroutine and return it. When the sub returns the coroutine 354Create a new coroutine and return it. When the sub returns the coroutine
260automatically terminates as if C<terminate> with the returned values were 355automatically terminates as if C<terminate> with the returned values were
261called. To make the coroutine run you must first put it into the ready queue 356called. To make the coroutine run you must first put it into the ready queue
262by calling the ready method. 357by calling the ready method.
263 358
264Calling C<exit> in a coroutine will not work correctly, so do not do that. 359See C<async> and C<Coro::State::new> for additional info about the
360coroutine environment.
265 361
266=cut 362=cut
267 363
268sub _run_coro { 364sub _run_coro {
269 terminate &{+shift}; 365 terminate &{+shift};
286Return wether the coroutine is currently the ready queue or not, 382Return wether the coroutine is currently the ready queue or not,
287 383
288=item $coroutine->cancel (arg...) 384=item $coroutine->cancel (arg...)
289 385
290Terminates the given coroutine and makes it return the given arguments as 386Terminates the given coroutine and makes it return the given arguments as
291status (default: the empty list). 387status (default: the empty list). Never returns if the coroutine is the
388current coroutine.
292 389
293=cut 390=cut
294 391
295sub cancel { 392sub cancel {
296 my $self = shift; 393 my $self = shift;
297 $self->{status} = [@_]; 394 $self->{_status} = [@_];
395
396 if ($current == $self) {
298 push @destroy, $self; 397 push @destroy, $self;
299 $manager->ready; 398 $manager->ready;
300 &schedule if $current == $self; 399 &schedule while 1;
400 } else {
401 $self->_cancel;
402 }
301} 403}
302 404
303=item $coroutine->join 405=item $coroutine->join
304 406
305Wait until the coroutine terminates and return any values given to the 407Wait until the coroutine terminates and return any values given to the
306C<terminate> or C<cancel> functions. C<join> can be called multiple times 408C<terminate> or C<cancel> functions. C<join> can be called concurrently
307from multiple coroutine. 409from multiple coroutines.
308 410
309=cut 411=cut
310 412
311sub join { 413sub join {
312 my $self = shift; 414 my $self = shift;
415
313 unless ($self->{status}) { 416 unless ($self->{_status}) {
314 push @{$self->{join}}, $current; 417 my $current = $current;
315 &schedule; 418
419 push @{$self->{_on_destroy}}, sub {
420 $current->ready;
421 undef $current;
422 };
423
424 &schedule while $current;
316 } 425 }
426
317 wantarray ? @{$self->{status}} : $self->{status}[0]; 427 wantarray ? @{$self->{_status}} : $self->{_status}[0];
428}
429
430=item $coroutine->on_destroy (\&cb)
431
432Registers a callback that is called when this coroutine gets destroyed,
433but before it is joined. The callback gets passed the terminate arguments,
434if any.
435
436=cut
437
438sub on_destroy {
439 my ($self, $cb) = @_;
440
441 push @{ $self->{_on_destroy} }, $cb;
318} 442}
319 443
320=item $oldprio = $coroutine->prio ($newprio) 444=item $oldprio = $coroutine->prio ($newprio)
321 445
322Sets (or gets, if the argument is missing) the priority of the 446Sets (or gets, if the argument is missing) the priority of the
347=item $olddesc = $coroutine->desc ($newdesc) 471=item $olddesc = $coroutine->desc ($newdesc)
348 472
349Sets (or gets in case the argument is missing) the description for this 473Sets (or gets in case the argument is missing) the description for this
350coroutine. This is just a free-form string you can associate with a coroutine. 474coroutine. This is just a free-form string you can associate with a coroutine.
351 475
476This method simply sets the C<< $coroutine->{desc} >> member to the given string. You
477can modify this member directly if you wish.
478
479=item $coroutine->throw ([$scalar])
480
481If C<$throw> is specified and defined, it will be thrown as an exception
482inside the coroutine at the next convinient point in time (usually after
483it gains control at the next schedule/transfer/cede). Otherwise clears the
484exception object.
485
486The exception object will be thrown "as is" with the specified scalar in
487C<$@>, i.e. if it is a string, no line number or newline will be appended
488(unlike with C<die>).
489
490This can be used as a softer means than C<cancel> to ask a coroutine to
491end itself, although there is no guarentee that the exception will lead to
492termination, and if the exception isn't caught it might well end the whole
493program.
494
352=cut 495=cut
353 496
354sub desc { 497sub desc {
355 my $old = $_[0]{desc}; 498 my $old = $_[0]{desc};
356 $_[0]{desc} = $_[1] if @_ > 1; 499 $_[0]{desc} = $_[1] if @_ > 1;
364=over 4 507=over 4
365 508
366=item Coro::nready 509=item Coro::nready
367 510
368Returns the number of coroutines that are currently in the ready state, 511Returns the number of coroutines that are currently in the ready state,
369i.e. that can be swicthed to. The value C<0> means that the only runnable 512i.e. that can be switched to. The value C<0> means that the only runnable
370coroutine is the currently running one, so C<cede> would have no effect, 513coroutine is the currently running one, so C<cede> would have no effect,
371and C<schedule> would cause a deadlock unless there is an idle handler 514and C<schedule> would cause a deadlock unless there is an idle handler
372that wakes up some coroutines. 515that wakes up some coroutines.
516
517=item my $guard = Coro::guard { ... }
518
519This creates and returns a guard object. Nothing happens until the object
520gets destroyed, in which case the codeblock given as argument will be
521executed. This is useful to free locks or other resources in case of a
522runtime error or when the coroutine gets canceled, as in both cases the
523guard block will be executed. The guard object supports only one method,
524C<< ->cancel >>, which will keep the codeblock from being executed.
525
526Example: set some flag and clear it again when the coroutine gets canceled
527or the function returns:
528
529 sub do_something {
530 my $guard = Coro::guard { $busy = 0 };
531 $busy = 1;
532
533 # do something that requires $busy to be true
534 }
535
536=cut
537
538sub guard(&) {
539 bless \(my $cb = $_[0]), "Coro::guard"
540}
541
542sub Coro::guard::cancel {
543 ${$_[0]} = sub { };
544}
545
546sub Coro::guard::DESTROY {
547 ${$_[0]}->();
548}
549
373 550
374=item unblock_sub { ... } 551=item unblock_sub { ... }
375 552
376This utility function takes a BLOCK or code reference and "unblocks" it, 553This utility function takes a BLOCK or code reference and "unblocks" it,
377returning the new coderef. This means that the new coderef will return 554returning the new coderef. This means that the new coderef will return
378immediately without blocking, returning nothing, while the original code 555immediately without blocking, returning nothing, while the original code
379ref will be called (with parameters) from within its own coroutine. 556ref will be called (with parameters) from within its own coroutine.
380 557
381The reason this fucntion exists is that many event libraries (such as the 558The reason this function exists is that many event libraries (such as the
382venerable L<Event|Event> module) are not coroutine-safe (a weaker form 559venerable L<Event|Event> module) are not coroutine-safe (a weaker form
383of thread-safety). This means you must not block within event callbacks, 560of thread-safety). This means you must not block within event callbacks,
384otherwise you might suffer from crashes or worse. 561otherwise you might suffer from crashes or worse.
385 562
386This function allows your callbacks to block by executing them in another 563This function allows your callbacks to block by executing them in another
391In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when 568In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
392creating event callbacks that want to block. 569creating event callbacks that want to block.
393 570
394=cut 571=cut
395 572
396our @unblock_pool;
397our @unblock_queue; 573our @unblock_queue;
398our $UNBLOCK_POOL_SIZE = 2;
399 574
400sub unblock_handler_ { 575# we create a special coro because we want to cede,
401 while () { 576# to reduce pressure on the coro pool (because most callbacks
402 my ($cb, @arg) = @{ delete $Coro::current->{arg} }; 577# return immediately and can be reused) and because we cannot cede
403 $cb->(@arg); 578# inside an event callback.
404
405 last if @unblock_pool >= $UNBLOCK_POOL_SIZE;
406 push @unblock_pool, $Coro::current;
407 schedule;
408 }
409}
410
411our $unblock_scheduler = async { 579our $unblock_scheduler = new Coro sub {
412 while () { 580 while () {
413 while (my $cb = pop @unblock_queue) { 581 while (my $cb = pop @unblock_queue) {
414 my $handler = (pop @unblock_pool or new Coro \&unblock_handler_); 582 # this is an inlined copy of async_pool
415 $handler->{arg} = $cb; 583 my $coro = (pop @async_pool) || new Coro \&pool_handler;
584
585 $coro->{_invoke} = $cb;
416 $handler->ready; 586 $coro->ready;
417 cede; 587 cede; # for short-lived callbacks, this reduces pressure on the coro pool
418 } 588 }
419 589 schedule; # sleep well
420 schedule;
421 } 590 }
422}; 591};
592$unblock_scheduler->desc ("[unblock_sub scheduler]");
423 593
424sub unblock_sub(&) { 594sub unblock_sub(&) {
425 my $cb = shift; 595 my $cb = shift;
426 596
427 sub { 597 sub {
428 push @unblock_queue, [$cb, @_]; 598 unshift @unblock_queue, [$cb, @_];
429 $unblock_scheduler->ready; 599 $unblock_scheduler->ready;
430 } 600 }
431} 601}
432 602
433=back 603=back
440 610
441 - you must make very sure that no coro is still active on global 611 - you must make very sure that no coro is still active on global
442 destruction. very bad things might happen otherwise (usually segfaults). 612 destruction. very bad things might happen otherwise (usually segfaults).
443 613
444 - this module is not thread-safe. You should only ever use this module 614 - this module is not thread-safe. You should only ever use this module
445 from the same thread (this requirement might be losened in the future 615 from the same thread (this requirement might be loosened in the future
446 to allow per-thread schedulers, but Coro::State does not yet allow 616 to allow per-thread schedulers, but Coro::State does not yet allow
447 this). 617 this).
448 618
449=head1 SEE ALSO 619=head1 SEE ALSO
450 620
621Lower level Configuration, Coroutine Environment: L<Coro::State>.
622
623Debugging: L<Coro::Debug>.
624
451Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>. 625Support/Utility: L<Coro::Specific>, L<Coro::Util>.
452 626
453Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>. 627Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
454 628
455Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>. 629Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>.
456 630
631Compatibility: L<Coro::LWP>, L<Coro::Storable>, L<Coro::Select>.
632
457Embedding: L<Coro:MakeMaker> 633Embedding: L<Coro::MakeMaker>.
458 634
459=head1 AUTHOR 635=head1 AUTHOR
460 636
461 Marc Lehmann <schmorp@schmorp.de> 637 Marc Lehmann <schmorp@schmorp.de>
462 http://home.schmorp.de/ 638 http://home.schmorp.de/

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