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Revision 1.101 by root, Fri Dec 29 08:36:34 2006 UTC vs.
Revision 1.152 by root, Sun Oct 7 13:53:37 2007 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 $VERSION = '4.1';
56 63
57our @EXPORT = qw(async cede schedule terminate current unblock_sub); 64our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
58our %EXPORT_TAGS = ( 65our %EXPORT_TAGS = (
59 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], 66 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
60); 67);
61our @EXPORT_OK = (@{$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};
180$manager->desc ("[coro manager]");
181$manager->prio (PRIO_MAX);
173 182
174# static methods. not really. 183# static methods. not really.
175 184
176=back 185=back
177 186
185 194
186Create a new asynchronous coroutine and return it's coroutine object 195Create a new asynchronous coroutine and return it's coroutine object
187(usually unused). When the sub returns the new coroutine is automatically 196(usually unused). When the sub returns the new coroutine is automatically
188terminated. 197terminated.
189 198
190Calling 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.
191 201
192When 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
193program. 203the coroutine. Likewise, when the coroutine dies, the program will exit,
204just as it would in the main program.
194 205
195 # create a new coroutine that just prints its arguments 206 # create a new coroutine that just prints its arguments
196 async { 207 async {
197 print "@_\n"; 208 print "@_\n";
198 } 1,2,3,4; 209 } 1,2,3,4;
199 210
200=cut 211=cut
201 212
202sub async(&@) { 213sub async(&@) {
203 my $pid = new Coro @_; 214 my $coro = new Coro @_;
204 $pid->ready; 215 $coro->ready;
205 $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
206} 280}
207 281
208=item schedule 282=item schedule
209 283
210Calls 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
223 # wake up sleeping coroutine 297 # wake up sleeping coroutine
224 $current->ready; 298 $current->ready;
225 undef $current; 299 undef $current;
226 }; 300 };
227 301
228 # call schedule until event occured. 302 # call schedule until event occurred.
229 # in case we are woken up for other reasons 303 # in case we are woken up for other reasons
230 # (current still defined), loop. 304 # (current still defined), loop.
231 Coro::schedule while $current; 305 Coro::schedule while $current;
232 } 306 }
233 307
235 309
236"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
237ready 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
238current "timeslice" to other coroutines of the same or higher priority. 312current "timeslice" to other coroutines of the same or higher priority.
239 313
314Returns true if at least one coroutine switch has happened.
315
316=item Coro::cede_notself
317
318Works like cede, but is not exported by default and will cede to any
319coroutine, regardless of priority, once.
320
321Returns true if at least one coroutine switch has happened.
322
240=item terminate [arg...] 323=item terminate [arg...]
241 324
242Terminates the current coroutine with the given status values (see L<cancel>). 325Terminates the current coroutine with the given status values (see L<cancel>).
326
327=item killall
328
329Kills/terminates/cancels all coroutines except the currently running
330one. This is useful after a fork, either in the child or the parent, as
331usually only one of them should inherit the running coroutines.
243 332
244=cut 333=cut
245 334
246sub terminate { 335sub terminate {
247 $current->cancel (@_); 336 $current->cancel (@_);
337}
338
339sub killall {
340 for (Coro::State::list) {
341 $_->cancel
342 if $_ != $current && UNIVERSAL::isa $_, "Coro";
343 }
248} 344}
249 345
250=back 346=back
251 347
252# dynamic methods 348# dynamic methods
262Create a new coroutine and return it. When the sub returns the coroutine 358Create a new coroutine and return it. When the sub returns the coroutine
263automatically terminates as if C<terminate> with the returned values were 359automatically 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 360called. To make the coroutine run you must first put it into the ready queue
265by calling the ready method. 361by calling the ready method.
266 362
267Calling C<exit> in a coroutine will not work correctly, so do not do that. 363See C<async> and C<Coro::State::new> for additional info about the
364coroutine environment.
268 365
269=cut 366=cut
270 367
271sub _run_coro { 368sub _run_coro {
272 terminate &{+shift}; 369 terminate &{+shift};
289Return wether the coroutine is currently the ready queue or not, 386Return wether the coroutine is currently the ready queue or not,
290 387
291=item $coroutine->cancel (arg...) 388=item $coroutine->cancel (arg...)
292 389
293Terminates the given coroutine and makes it return the given arguments as 390Terminates the given coroutine and makes it return the given arguments as
294status (default: the empty list). 391status (default: the empty list). Never returns if the coroutine is the
392current coroutine.
295 393
296=cut 394=cut
297 395
298sub cancel { 396sub cancel {
299 my $self = shift; 397 my $self = shift;
300 $self->{status} = [@_]; 398 $self->{_status} = [@_];
399
400 if ($current == $self) {
301 push @destroy, $self; 401 push @destroy, $self;
302 $manager->ready; 402 $manager->ready;
303 &schedule if $current == $self; 403 &schedule while 1;
404 } else {
405 $self->_cancel;
406 }
304} 407}
305 408
306=item $coroutine->join 409=item $coroutine->join
307 410
308Wait until the coroutine terminates and return any values given to the 411Wait until the coroutine terminates and return any values given to the
309C<terminate> or C<cancel> functions. C<join> can be called multiple times 412C<terminate> or C<cancel> functions. C<join> can be called concurrently
310from multiple coroutine. 413from multiple coroutines.
311 414
312=cut 415=cut
313 416
314sub join { 417sub join {
315 my $self = shift; 418 my $self = shift;
419
316 unless ($self->{status}) { 420 unless ($self->{_status}) {
317 push @{$self->{join}}, $current; 421 my $current = $current;
318 &schedule; 422
423 push @{$self->{_on_destroy}}, sub {
424 $current->ready;
425 undef $current;
426 };
427
428 &schedule while $current;
319 } 429 }
430
320 wantarray ? @{$self->{status}} : $self->{status}[0]; 431 wantarray ? @{$self->{_status}} : $self->{_status}[0];
321} 432}
322 433
323=item $coroutine->on_destroy (\&cb) 434=item $coroutine->on_destroy (\&cb)
324 435
325Registers a callback that is called when this coroutine gets destroyed, 436Registers a callback that is called when this coroutine gets destroyed,
329=cut 440=cut
330 441
331sub on_destroy { 442sub on_destroy {
332 my ($self, $cb) = @_; 443 my ($self, $cb) = @_;
333 444
334 push @{ $self->{destroy_cb} }, $cb; 445 push @{ $self->{_on_destroy} }, $cb;
335} 446}
336 447
337=item $oldprio = $coroutine->prio ($newprio) 448=item $oldprio = $coroutine->prio ($newprio)
338 449
339Sets (or gets, if the argument is missing) the priority of the 450Sets (or gets, if the argument is missing) the priority of the
364=item $olddesc = $coroutine->desc ($newdesc) 475=item $olddesc = $coroutine->desc ($newdesc)
365 476
366Sets (or gets in case the argument is missing) the description for this 477Sets (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. 478coroutine. This is just a free-form string you can associate with a coroutine.
368 479
480This method simply sets the C<< $coroutine->{desc} >> member to the given string. You
481can modify this member directly if you wish.
482
483=item $coroutine->throw ([$scalar])
484
485If C<$throw> is specified and defined, it will be thrown as an exception
486inside the coroutine at the next convinient point in time (usually after
487it gains control at the next schedule/transfer/cede). Otherwise clears the
488exception object.
489
490The exception object will be thrown "as is" with the specified scalar in
491C<$@>, i.e. if it is a string, no line number or newline will be appended
492(unlike with C<die>).
493
494This can be used as a softer means than C<cancel> to ask a coroutine to
495end itself, although there is no guarentee that the exception will lead to
496termination, and if the exception isn't caught it might well end the whole
497program.
498
369=cut 499=cut
370 500
371sub desc { 501sub desc {
372 my $old = $_[0]{desc}; 502 my $old = $_[0]{desc};
373 $_[0]{desc} = $_[1] if @_ > 1; 503 $_[0]{desc} = $_[1] if @_ > 1;
381=over 4 511=over 4
382 512
383=item Coro::nready 513=item Coro::nready
384 514
385Returns the number of coroutines that are currently in the ready state, 515Returns 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 516i.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, 517coroutine 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 518and C<schedule> would cause a deadlock unless there is an idle handler
389that wakes up some coroutines. 519that wakes up some coroutines.
520
521=item my $guard = Coro::guard { ... }
522
523This creates and returns a guard object. Nothing happens until the object
524gets destroyed, in which case the codeblock given as argument will be
525executed. This is useful to free locks or other resources in case of a
526runtime error or when the coroutine gets canceled, as in both cases the
527guard block will be executed. The guard object supports only one method,
528C<< ->cancel >>, which will keep the codeblock from being executed.
529
530Example: set some flag and clear it again when the coroutine gets canceled
531or the function returns:
532
533 sub do_something {
534 my $guard = Coro::guard { $busy = 0 };
535 $busy = 1;
536
537 # do something that requires $busy to be true
538 }
539
540=cut
541
542sub guard(&) {
543 bless \(my $cb = $_[0]), "Coro::guard"
544}
545
546sub Coro::guard::cancel {
547 ${$_[0]} = sub { };
548}
549
550sub Coro::guard::DESTROY {
551 ${$_[0]}->();
552}
553
390 554
391=item unblock_sub { ... } 555=item unblock_sub { ... }
392 556
393This utility function takes a BLOCK or code reference and "unblocks" it, 557This utility function takes a BLOCK or code reference and "unblocks" it,
394returning the new coderef. This means that the new coderef will return 558returning the new coderef. This means that the new coderef will return
395immediately without blocking, returning nothing, while the original code 559immediately without blocking, returning nothing, while the original code
396ref will be called (with parameters) from within its own coroutine. 560ref will be called (with parameters) from within its own coroutine.
397 561
398The reason this fucntion exists is that many event libraries (such as the 562The reason this function exists is that many event libraries (such as the
399venerable L<Event|Event> module) are not coroutine-safe (a weaker form 563venerable L<Event|Event> module) are not coroutine-safe (a weaker form
400of thread-safety). This means you must not block within event callbacks, 564of thread-safety). This means you must not block within event callbacks,
401otherwise you might suffer from crashes or worse. 565otherwise you might suffer from crashes or worse.
402 566
403This function allows your callbacks to block by executing them in another 567This function allows your callbacks to block by executing them in another
408In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when 572In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
409creating event callbacks that want to block. 573creating event callbacks that want to block.
410 574
411=cut 575=cut
412 576
413our @unblock_pool;
414our @unblock_queue; 577our @unblock_queue;
415our $UNBLOCK_POOL_SIZE = 2;
416 578
417sub unblock_handler_ { 579# we create a special coro because we want to cede,
418 while () { 580# to reduce pressure on the coro pool (because most callbacks
419 my ($cb, @arg) = @{ delete $Coro::current->{arg} }; 581# return immediately and can be reused) and because we cannot cede
420 $cb->(@arg); 582# 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 { 583our $unblock_scheduler = new Coro sub {
429 while () { 584 while () {
430 while (my $cb = pop @unblock_queue) { 585 while (my $cb = pop @unblock_queue) {
431 my $handler = (pop @unblock_pool or new Coro \&unblock_handler_); 586 # this is an inlined copy of async_pool
432 $handler->{arg} = $cb; 587 my $coro = (pop @async_pool) || new Coro \&pool_handler;
588
589 $coro->{_invoke} = $cb;
433 $handler->ready; 590 $coro->ready;
434 cede; 591 cede; # for short-lived callbacks, this reduces pressure on the coro pool
435 } 592 }
436 593 schedule; # sleep well
437 schedule;
438 } 594 }
439}; 595};
596$unblock_scheduler->desc ("[unblock_sub scheduler]");
440 597
441sub unblock_sub(&) { 598sub unblock_sub(&) {
442 my $cb = shift; 599 my $cb = shift;
443 600
444 sub { 601 sub {
445 push @unblock_queue, [$cb, @_]; 602 unshift @unblock_queue, [$cb, @_];
446 $unblock_scheduler->ready; 603 $unblock_scheduler->ready;
447 } 604 }
448} 605}
449 606
450=back 607=back
457 614
458 - you must make very sure that no coro is still active on global 615 - you must make very sure that no coro is still active on global
459 destruction. very bad things might happen otherwise (usually segfaults). 616 destruction. very bad things might happen otherwise (usually segfaults).
460 617
461 - this module is not thread-safe. You should only ever use this module 618 - 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 619 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 620 to allow per-thread schedulers, but Coro::State does not yet allow
464 this). 621 this).
465 622
466=head1 SEE ALSO 623=head1 SEE ALSO
467 624
625Lower level Configuration, Coroutine Environment: L<Coro::State>.
626
627Debugging: L<Coro::Debug>.
628
468Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>. 629Support/Utility: L<Coro::Specific>, L<Coro::Util>.
469 630
470Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>. 631Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
471 632
472Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>. 633Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>.
473 634
635Compatibility: L<Coro::LWP>, L<Coro::Storable>, L<Coro::Select>.
636
474Embedding: L<Coro:MakeMaker> 637Embedding: L<Coro:MakeMaker>.
475 638
476=head1 AUTHOR 639=head1 AUTHOR
477 640
478 Marc Lehmann <schmorp@schmorp.de> 641 Marc Lehmann <schmorp@schmorp.de>
479 http://home.schmorp.de/ 642 http://home.schmorp.de/

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