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Revision 1.105 by root, Fri Jan 5 16:55:01 2007 UTC vs.
Revision 1.148 by root, Fri Oct 5 20:11:25 2007 UTC

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20 20
21=head1 DESCRIPTION 21=head1 DESCRIPTION
22 22
23This module collection manages coroutines. Coroutines are similar 23This module collection manages coroutines. Coroutines are similar
24to threads but don't run in parallel at the same time even on SMP 24to 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 25machines. The specific flavor of coroutine used in this module also
26guarentees you that it will not switch between coroutines unless 26guarantees you that it will not switch between coroutines unless
27necessary, at easily-identified points in your program, so locking and 27necessary, at easily-identified points in your program, so locking and
28parallel access are rarely an issue, making coroutine programming much 28parallel access are rarely an issue, making coroutine programming much
29safer than threads programming. 29safer than threads programming.
30 30
31(Perl, however, does not natively support real threads but instead does a 31(Perl, however, does not natively support real threads but instead does a
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50 50
51our $idle; # idle handler 51our $idle; # idle handler
52our $main; # main coroutine 52our $main; # main coroutine
53our $current; # current coroutine 53our $current; # current coroutine
54 54
55our $VERSION = '3.3'; 55our $VERSION = '4.01';
56 56
57our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); 57our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
58our %EXPORT_TAGS = ( 58our %EXPORT_TAGS = (
59 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], 59 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
60); 60);
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108 108
109The current coroutine (the last coroutine switched to). The initial value 109The current coroutine (the last coroutine switched to). The initial value
110is C<$main> (of course). 110is C<$main> (of course).
111 111
112This variable is B<strictly> I<read-only>. It is provided for performance 112This variable is B<strictly> I<read-only>. It is provided for performance
113reasons. If performance is not essentiel you are encouraged to use the 113reasons. If performance is not essential you are encouraged to use the
114C<Coro::current> function instead. 114C<Coro::current> function instead.
115 115
116=cut 116=cut
117 117
118$main->{desc} = "[main::]";
119
118# maybe some other module used Coro::Specific before... 120# maybe some other module used Coro::Specific before...
119$main->{specific} = $current->{specific} 121$main->{_specific} = $current->{_specific}
120 if $current; 122 if $current;
121 123
122_set_current $main; 124_set_current $main;
123 125
124sub current() { $current } 126sub current() { $current }
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149 # free coroutine data and mark as destructed 151 # free coroutine data and mark as destructed
150 $self->_destroy 152 $self->_destroy
151 or return; 153 or return;
152 154
153 # call all destruction callbacks 155 # call all destruction callbacks
154 $_->(@{$self->{status}}) 156 $_->(@{$self->{_status}})
155 for @{(delete $self->{destroy_cb}) || []}; 157 for @{(delete $self->{_on_destroy}) || []};
156} 158}
157 159
158# this coroutine is necessary because a coroutine 160# this coroutine is necessary because a coroutine
159# cannot destroy itself. 161# cannot destroy itself.
160my @destroy; 162my @destroy;
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166 while @destroy; 168 while @destroy;
167 169
168 &schedule; 170 &schedule;
169 } 171 }
170}; 172};
171 173$manager->desc ("[coro manager]");
172$manager->prio (PRIO_MAX); 174$manager->prio (PRIO_MAX);
173 175
174# static methods. not really. 176# static methods. not really.
175 177
176=back 178=back
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185 187
186Create a new asynchronous coroutine and return it's coroutine object 188Create a new asynchronous coroutine and return it's coroutine object
187(usually unused). When the sub returns the new coroutine is automatically 189(usually unused). When the sub returns the new coroutine is automatically
188terminated. 190terminated.
189 191
190Calling C<exit> in a coroutine will not work correctly, so do not do that. 192See the C<Coro::State::new> constructor for info about the coroutine
193environment.
191 194
192When the coroutine dies, the program will exit, just as in the main 195Calling C<exit> in a coroutine will do the same as calling exit outside
193program. 196the coroutine. Likewise, when the coroutine dies, the program will exit,
197just as it would in the main program.
194 198
195 # create a new coroutine that just prints its arguments 199 # create a new coroutine that just prints its arguments
196 async { 200 async {
197 print "@_\n"; 201 print "@_\n";
198 } 1,2,3,4; 202 } 1,2,3,4;
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210Similar to C<async>, but uses a coroutine pool, so you should not call 214Similar to C<async>, but uses a coroutine pool, so you should not call
211terminate or join (although you are allowed to), and you get a coroutine 215terminate or join (although you are allowed to), and you get a coroutine
212that might have executed other code already (which can be good or bad :). 216that might have executed other code already (which can be good or bad :).
213 217
214Also, the block is executed in an C<eval> context and a warning will be 218Also, the block is executed in an C<eval> context and a warning will be
215issued in case of an exception instead of terminating the program, as C<async> does. 219issued in case of an exception instead of terminating the program, as
220C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
221will not work in the expected way, unless you call terminate or cancel,
222which somehow defeats the purpose of pooling.
216 223
217The priority will be reset to C<0> after each job, otherwise the coroutine 224The priority will be reset to C<0> after each job, tracing will be
218will be re-used "as-is". 225disabled, the description will be reset and the default output filehandle
226gets restored, so you can change alkl these. Otherwise the coroutine will
227be re-used "as-is": most notably if you change other per-coroutine global
228stuff such as C<$/> you need to revert that change, which is most simply
229done by using local as in C< local $/ >.
219 230
220The pool size is limited to 8 idle coroutines (this can be adjusted by 231The pool size is limited to 8 idle coroutines (this can be adjusted by
221changing $Coro::POOL_SIZE), and there can be as many non-idle coros as 232changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
222required. 233required.
223 234
224If you are concerned about pooled coroutines growing a lot because a 235If you are concerned about pooled coroutines growing a lot because a
225single C<async_pool> used a lot of stackspace you can e.g. C<async_pool { 236single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
226terminate }> once per second or so to slowly replenish the pool. 237{ terminate }> once per second or so to slowly replenish the pool. In
238addition to that, when the stacks used by a handler grows larger than 16kb
239(adjustable with $Coro::POOL_RSS) it will also exit.
227 240
228=cut 241=cut
229 242
230our $POOL_SIZE = 8; 243our $POOL_SIZE = 8;
244our $POOL_RSS = 16 * 1024;
231our @pool; 245our @async_pool;
232 246
233sub pool_handler { 247sub pool_handler {
248 my $cb;
249
234 while () { 250 while () {
235 my ($cb, @arg) = @{ delete $current->{_invoke} };
236
237 eval { 251 eval {
238 $cb->(@arg); 252 while () {
253 _pool_1 $cb;
254 &$cb;
255 _pool_2 $cb;
256 &schedule;
257 }
239 }; 258 };
259
260 last if $@ eq "\3terminate\2\n";
240 warn $@ if $@; 261 warn $@ if $@;
241 262 }
242 last if @pool >= $POOL_SIZE; 263}
243 push @pool, $current;
244
245 $current->prio (0);
246 schedule;
247 }
248}
249 264
250sub async_pool(&@) { 265sub async_pool(&@) {
251 # this is also inlined into the unlock_scheduler 266 # this is also inlined into the unlock_scheduler
252 my $coro = (pop @pool or new Coro \&pool_handler); 267 my $coro = (pop @async_pool) || new Coro \&pool_handler;
253 268
254 $coro->{_invoke} = [@_]; 269 $coro->{_invoke} = [@_];
255 $coro->ready; 270 $coro->ready;
256 271
257 $coro 272 $coro
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275 # wake up sleeping coroutine 290 # wake up sleeping coroutine
276 $current->ready; 291 $current->ready;
277 undef $current; 292 undef $current;
278 }; 293 };
279 294
280 # call schedule until event occured. 295 # call schedule until event occurred.
281 # in case we are woken up for other reasons 296 # in case we are woken up for other reasons
282 # (current still defined), loop. 297 # (current still defined), loop.
283 Coro::schedule while $current; 298 Coro::schedule while $current;
284 } 299 }
285 300
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287 302
288"Cede" to other coroutines. This function puts the current coroutine into the 303"Cede" to other coroutines. This function puts the current coroutine into the
289ready queue and calls C<schedule>, which has the effect of giving up the 304ready queue and calls C<schedule>, which has the effect of giving up the
290current "timeslice" to other coroutines of the same or higher priority. 305current "timeslice" to other coroutines of the same or higher priority.
291 306
307Returns true if at least one coroutine switch has happened.
308
292=item Coro::cede_notself 309=item Coro::cede_notself
293 310
294Works like cede, but is not exported by default and will cede to any 311Works like cede, but is not exported by default and will cede to any
295coroutine, regardless of priority, once. 312coroutine, regardless of priority, once.
296 313
314Returns true if at least one coroutine switch has happened.
315
297=item terminate [arg...] 316=item terminate [arg...]
298 317
299Terminates the current coroutine with the given status values (see L<cancel>). 318Terminates the current coroutine with the given status values (see L<cancel>).
319
320=item killall
321
322Kills/terminates/cancels all coroutines except the currently running
323one. This is useful after a fork, either in the child or the parent, as
324usually only one of them should inherit the running coroutines.
300 325
301=cut 326=cut
302 327
303sub terminate { 328sub terminate {
304 $current->cancel (@_); 329 $current->cancel (@_);
330}
331
332sub killall {
333 for (Coro::State::list) {
334 $_->cancel
335 if $_ != $current && UNIVERSAL::isa $_, "Coro";
336 }
305} 337}
306 338
307=back 339=back
308 340
309# dynamic methods 341# dynamic methods
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319Create a new coroutine and return it. When the sub returns the coroutine 351Create a new coroutine and return it. When the sub returns the coroutine
320automatically terminates as if C<terminate> with the returned values were 352automatically terminates as if C<terminate> with the returned values were
321called. To make the coroutine run you must first put it into the ready queue 353called. To make the coroutine run you must first put it into the ready queue
322by calling the ready method. 354by calling the ready method.
323 355
324Calling C<exit> in a coroutine will not work correctly, so do not do that. 356See C<async> and C<Coro::State::new> for additional info about the
357coroutine environment.
325 358
326=cut 359=cut
327 360
328sub _run_coro { 361sub _run_coro {
329 terminate &{+shift}; 362 terminate &{+shift};
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353 386
354=cut 387=cut
355 388
356sub cancel { 389sub cancel {
357 my $self = shift; 390 my $self = shift;
358 $self->{status} = [@_]; 391 $self->{_status} = [@_];
359 392
360 if ($current == $self) { 393 if ($current == $self) {
361 push @destroy, $self; 394 push @destroy, $self;
362 $manager->ready; 395 $manager->ready;
363 &schedule while 1; 396 &schedule while 1;
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367} 400}
368 401
369=item $coroutine->join 402=item $coroutine->join
370 403
371Wait until the coroutine terminates and return any values given to the 404Wait until the coroutine terminates and return any values given to the
372C<terminate> or C<cancel> functions. C<join> can be called multiple times 405C<terminate> or C<cancel> functions. C<join> can be called concurrently
373from multiple coroutine. 406from multiple coroutines.
374 407
375=cut 408=cut
376 409
377sub join { 410sub join {
378 my $self = shift; 411 my $self = shift;
379 412
380 unless ($self->{status}) { 413 unless ($self->{_status}) {
381 my $current = $current; 414 my $current = $current;
382 415
383 push @{$self->{destroy_cb}}, sub { 416 push @{$self->{_on_destroy}}, sub {
384 $current->ready; 417 $current->ready;
385 undef $current; 418 undef $current;
386 }; 419 };
387 420
388 &schedule while $current; 421 &schedule while $current;
389 } 422 }
390 423
391 wantarray ? @{$self->{status}} : $self->{status}[0]; 424 wantarray ? @{$self->{_status}} : $self->{_status}[0];
392} 425}
393 426
394=item $coroutine->on_destroy (\&cb) 427=item $coroutine->on_destroy (\&cb)
395 428
396Registers a callback that is called when this coroutine gets destroyed, 429Registers a callback that is called when this coroutine gets destroyed,
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400=cut 433=cut
401 434
402sub on_destroy { 435sub on_destroy {
403 my ($self, $cb) = @_; 436 my ($self, $cb) = @_;
404 437
405 push @{ $self->{destroy_cb} }, $cb; 438 push @{ $self->{_on_destroy} }, $cb;
406} 439}
407 440
408=item $oldprio = $coroutine->prio ($newprio) 441=item $oldprio = $coroutine->prio ($newprio)
409 442
410Sets (or gets, if the argument is missing) the priority of the 443Sets (or gets, if the argument is missing) the priority of the
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435=item $olddesc = $coroutine->desc ($newdesc) 468=item $olddesc = $coroutine->desc ($newdesc)
436 469
437Sets (or gets in case the argument is missing) the description for this 470Sets (or gets in case the argument is missing) the description for this
438coroutine. This is just a free-form string you can associate with a coroutine. 471coroutine. This is just a free-form string you can associate with a coroutine.
439 472
473This method simply sets the C<< $coroutine->{desc} >> member to the given string. You
474can modify this member directly if you wish.
475
440=cut 476=cut
441 477
442sub desc { 478sub desc {
443 my $old = $_[0]{desc}; 479 my $old = $_[0]{desc};
444 $_[0]{desc} = $_[1] if @_ > 1; 480 $_[0]{desc} = $_[1] if @_ > 1;
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452=over 4 488=over 4
453 489
454=item Coro::nready 490=item Coro::nready
455 491
456Returns the number of coroutines that are currently in the ready state, 492Returns the number of coroutines that are currently in the ready state,
457i.e. that can be swicthed to. The value C<0> means that the only runnable 493i.e. that can be switched to. The value C<0> means that the only runnable
458coroutine is the currently running one, so C<cede> would have no effect, 494coroutine is the currently running one, so C<cede> would have no effect,
459and C<schedule> would cause a deadlock unless there is an idle handler 495and C<schedule> would cause a deadlock unless there is an idle handler
460that wakes up some coroutines. 496that wakes up some coroutines.
461 497
462=item my $guard = Coro::guard { ... } 498=item my $guard = Coro::guard { ... }
463 499
464This creates and returns a guard object. Nothing happens until the objetc 500This creates and returns a guard object. Nothing happens until the object
465gets destroyed, in which case the codeblock given as argument will be 501gets destroyed, in which case the codeblock given as argument will be
466executed. This is useful to free locks or other resources in case of a 502executed. This is useful to free locks or other resources in case of a
467runtime error or when the coroutine gets canceled, as in both cases the 503runtime error or when the coroutine gets canceled, as in both cases the
468guard block will be executed. The guard object supports only one method, 504guard block will be executed. The guard object supports only one method,
469C<< ->cancel >>, which will keep the codeblock from being executed. 505C<< ->cancel >>, which will keep the codeblock from being executed.
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498This utility function takes a BLOCK or code reference and "unblocks" it, 534This utility function takes a BLOCK or code reference and "unblocks" it,
499returning the new coderef. This means that the new coderef will return 535returning the new coderef. This means that the new coderef will return
500immediately without blocking, returning nothing, while the original code 536immediately without blocking, returning nothing, while the original code
501ref will be called (with parameters) from within its own coroutine. 537ref will be called (with parameters) from within its own coroutine.
502 538
503The reason this fucntion exists is that many event libraries (such as the 539The reason this function exists is that many event libraries (such as the
504venerable L<Event|Event> module) are not coroutine-safe (a weaker form 540venerable L<Event|Event> module) are not coroutine-safe (a weaker form
505of thread-safety). This means you must not block within event callbacks, 541of thread-safety). This means you must not block within event callbacks,
506otherwise you might suffer from crashes or worse. 542otherwise you might suffer from crashes or worse.
507 543
508This function allows your callbacks to block by executing them in another 544This function allows your callbacks to block by executing them in another
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519 555
520# we create a special coro because we want to cede, 556# we create a special coro because we want to cede,
521# to reduce pressure on the coro pool (because most callbacks 557# to reduce pressure on the coro pool (because most callbacks
522# return immediately and can be reused) and because we cannot cede 558# return immediately and can be reused) and because we cannot cede
523# inside an event callback. 559# inside an event callback.
524our $unblock_scheduler = async { 560our $unblock_scheduler = new Coro sub {
525 while () { 561 while () {
526 while (my $cb = pop @unblock_queue) { 562 while (my $cb = pop @unblock_queue) {
527 # this is an inlined copy of async_pool 563 # this is an inlined copy of async_pool
528 my $coro = (pop @pool or new Coro \&pool_handler); 564 my $coro = (pop @async_pool) || new Coro \&pool_handler;
529 565
530 $coro->{_invoke} = $cb; 566 $coro->{_invoke} = $cb;
531 $coro->ready; 567 $coro->ready;
532 cede; # for short-lived callbacks, this reduces pressure on the coro pool 568 cede; # for short-lived callbacks, this reduces pressure on the coro pool
533 } 569 }
534 schedule; # sleep well 570 schedule; # sleep well
535 } 571 }
536}; 572};
573$unblock_scheduler->desc ("[unblock_sub scheduler]");
537 574
538sub unblock_sub(&) { 575sub unblock_sub(&) {
539 my $cb = shift; 576 my $cb = shift;
540 577
541 sub { 578 sub {
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554 591
555 - you must make very sure that no coro is still active on global 592 - you must make very sure that no coro is still active on global
556 destruction. very bad things might happen otherwise (usually segfaults). 593 destruction. very bad things might happen otherwise (usually segfaults).
557 594
558 - this module is not thread-safe. You should only ever use this module 595 - this module is not thread-safe. You should only ever use this module
559 from the same thread (this requirement might be losened in the future 596 from the same thread (this requirement might be loosened in the future
560 to allow per-thread schedulers, but Coro::State does not yet allow 597 to allow per-thread schedulers, but Coro::State does not yet allow
561 this). 598 this).
562 599
563=head1 SEE ALSO 600=head1 SEE ALSO
564 601
565Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>. 602Support/Utility: L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.
566 603
567Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>. 604Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
568 605
569Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>. 606Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.
570 607

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