ViewVC Help
View File | Revision Log | Show Annotations | Download File
/cvs/Coro/Coro.pm
(Generate patch)

Comparing Coro/Coro.pm (file contents):
Revision 1.92 by root, Fri Dec 1 03:47:55 2006 UTC vs.
Revision 1.150 by root, Sat Oct 6 01:11:01 2007 UTC

18 18
19 cede; 19 cede;
20 20
21=head1 DESCRIPTION 21=head1 DESCRIPTION
22 22
23This module collection manages coroutines. Coroutines are similar to 23This module collection manages coroutines. Coroutines are similar
24threads but don't run in parallel. 24to threads but don't run in parallel at the same time even on SMP
25machines. The specific flavor of coroutine used in this module also
26guarantees you that it will not switch between coroutines unless
27necessary, at easily-identified points in your program, so locking and
28parallel access are rarely an issue, making coroutine programming much
29safer than threads programming.
25 30
31(Perl, however, does not natively support real threads but instead does a
32very slow and memory-intensive emulation of processes using threads. This
33is a performance win on Windows machines, and a loss everywhere else).
34
26In this module, coroutines are defined as "callchain + lexical variables 35In this module, coroutines are defined as "callchain + lexical variables +
27+ @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own 36@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,
28callchain, it's own set of lexicals and it's own set of perl's most 37its own set of lexicals and its own set of perls most important global
29important global variables. 38variables.
30 39
31=cut 40=cut
32 41
33package Coro; 42package Coro;
34 43
41 50
42our $idle; # idle handler 51our $idle; # idle handler
43our $main; # main coroutine 52our $main; # main coroutine
44our $current; # current coroutine 53our $current; # current coroutine
45 54
46our $VERSION = '3.0'; 55our $VERSION = '4.02';
47 56
48our @EXPORT = qw(async cede schedule terminate current unblock_sub); 57our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
49our %EXPORT_TAGS = ( 58our %EXPORT_TAGS = (
50 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], 59 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
51); 60);
52our @EXPORT_OK = @{$EXPORT_TAGS{prio}}; 61our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
53 62
54{ 63{
55 my @async; 64 my @async;
56 my $init; 65 my $init;
57 66
58 # this way of handling attributes simply is NOT scalable ;() 67 # this way of handling attributes simply is NOT scalable ;()
59 sub import { 68 sub import {
60 no strict 'refs'; 69 no strict 'refs';
61 70
62 Coro->export_to_level(1, @_); 71 Coro->export_to_level (1, @_);
63 72
64 my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE}; 73 my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
65 *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub { 74 *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
66 my ($package, $ref) = (shift, shift); 75 my ($package, $ref) = (shift, shift);
67 my @attrs; 76 my @attrs;
99 108
100The current coroutine (the last coroutine switched to). The initial value 109The current coroutine (the last coroutine switched to). The initial value
101is C<$main> (of course). 110is C<$main> (of course).
102 111
103This variable is B<strictly> I<read-only>. It is provided for performance 112This variable is B<strictly> I<read-only>. It is provided for performance
104reasons. If performance is not essentiel you are encouraged to use the 113reasons. If performance is not essential you are encouraged to use the
105C<Coro::current> function instead. 114C<Coro::current> function instead.
106 115
107=cut 116=cut
108 117
118$main->{desc} = "[main::]";
119
109# maybe some other module used Coro::Specific before... 120# maybe some other module used Coro::Specific before...
110if ($current) {
111 $main->{specific} = $current->{specific}; 121$main->{_specific} = $current->{_specific}
112} 122 if $current;
113 123
114$current = $main; 124_set_current $main;
115 125
116sub current() { $current } 126sub current() { $current }
117 127
118=item $idle 128=item $idle
119 129
129handlers), then it must be prepared to be called recursively. 139handlers), then it must be prepared to be called recursively.
130 140
131=cut 141=cut
132 142
133$idle = sub { 143$idle = sub {
134 print STDERR "FATAL: deadlock detected\n"; 144 require Carp;
135 exit (51); 145 Carp::croak ("FATAL: deadlock detected");
136}; 146};
147
148sub _cancel {
149 my ($self) = @_;
150
151 # free coroutine data and mark as destructed
152 $self->_destroy
153 or return;
154
155 # call all destruction callbacks
156 $_->(@{$self->{_status}})
157 for @{(delete $self->{_on_destroy}) || []};
158}
137 159
138# this coroutine is necessary because a coroutine 160# this coroutine is necessary because a coroutine
139# cannot destroy itself. 161# cannot destroy itself.
140my @destroy; 162my @destroy;
163my $manager;
164
141my $manager; $manager = new Coro sub { 165$manager = new Coro sub {
142 while () { 166 while () {
143 # by overwriting the state object with the manager we destroy it 167 (shift @destroy)->_cancel
144 # while still being able to schedule this coroutine (in case it has
145 # been readied multiple times. this is harmless since the manager
146 # can be called as many times as neccessary and will always
147 # remove itself from the runqueue
148 while (@destroy) { 168 while @destroy;
149 my $coro = pop @destroy;
150 $coro->{status} ||= [];
151 $_->ready for @{delete $coro->{join} || []};
152 169
153 # the next line destroys the coro state, but keeps the
154 # coroutine itself intact (we basically make it a zombie
155 # coroutine that always runs the manager thread, so it's possible
156 # to transfer() to this coroutine).
157 $coro->_clone_state_from ($manager);
158 }
159 &schedule; 170 &schedule;
160 } 171 }
161}; 172};
173$manager->desc ("[coro manager]");
174$manager->prio (PRIO_MAX);
162 175
163# static methods. not really. 176# static methods. not really.
164 177
165=back 178=back
166 179
174 187
175Create a new asynchronous coroutine and return it's coroutine object 188Create a new asynchronous coroutine and return it's coroutine object
176(usually unused). When the sub returns the new coroutine is automatically 189(usually unused). When the sub returns the new coroutine is automatically
177terminated. 190terminated.
178 191
179Calling 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.
180 194
181When 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
182program. 196the coroutine. Likewise, when the coroutine dies, the program will exit,
197just as it would in the main program.
183 198
184 # create a new coroutine that just prints its arguments 199 # create a new coroutine that just prints its arguments
185 async { 200 async {
186 print "@_\n"; 201 print "@_\n";
187 } 1,2,3,4; 202 } 1,2,3,4;
188 203
189=cut 204=cut
190 205
191sub async(&@) { 206sub async(&@) {
192 my $pid = new Coro @_; 207 my $coro = new Coro @_;
193 $pid->ready; 208 $coro->ready;
194 $pid 209 $coro
210}
211
212=item async_pool { ... } [@args...]
213
214Similar to C<async>, but uses a coroutine pool, so you should not call
215terminate or join (although you are allowed to), and you get a coroutine
216that might have executed other code already (which can be good or bad :).
217
218Also, the block is executed in an C<eval> context and a warning will be
219issued in case of an exception instead of terminating the program, as
220C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
221will not work in the expected way, unless you call terminate or cancel,
222which somehow defeats the purpose of pooling.
223
224The priority will be reset to C<0> after each job, tracing will be
225disabled, the description will be reset and the default output filehandle
226gets restored, so you can change alkl these. Otherwise the coroutine will
227be re-used "as-is": most notably if you change other per-coroutine global
228stuff such as C<$/> you need to revert that change, which is most simply
229done by using local as in C< local $/ >.
230
231The pool size is limited to 8 idle coroutines (this can be adjusted by
232changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
233required.
234
235If you are concerned about pooled coroutines growing a lot because a
236single C<async_pool> used a lot of stackspace you can e.g. C<async_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.
240
241=cut
242
243our $POOL_SIZE = 8;
244our $POOL_RSS = 16 * 1024;
245our @async_pool;
246
247sub pool_handler {
248 my $cb;
249
250 while () {
251 eval {
252 while () {
253 _pool_1 $cb;
254 &$cb;
255 _pool_2 $cb;
256 &schedule;
257 }
258 };
259
260 last if $@ eq "\3terminate\2\n";
261 warn $@ if $@;
262 }
263}
264
265sub async_pool(&@) {
266 # this is also inlined into the unlock_scheduler
267 my $coro = (pop @async_pool) || new Coro \&pool_handler;
268
269 $coro->{_invoke} = [@_];
270 $coro->ready;
271
272 $coro
195} 273}
196 274
197=item schedule 275=item schedule
198 276
199Calls the scheduler. Please note that the current coroutine will not be put 277Calls the scheduler. Please note that the current coroutine will not be put
212 # wake up sleeping coroutine 290 # wake up sleeping coroutine
213 $current->ready; 291 $current->ready;
214 undef $current; 292 undef $current;
215 }; 293 };
216 294
217 # call schedule until event occured. 295 # call schedule until event occurred.
218 # in case we are woken up for other reasons 296 # in case we are woken up for other reasons
219 # (current still defined), loop. 297 # (current still defined), loop.
220 Coro::schedule while $current; 298 Coro::schedule while $current;
221 } 299 }
222 300
224 302
225"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
226ready 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
227current "timeslice" to other coroutines of the same or higher priority. 305current "timeslice" to other coroutines of the same or higher priority.
228 306
307Returns true if at least one coroutine switch has happened.
308
309=item Coro::cede_notself
310
311Works like cede, but is not exported by default and will cede to any
312coroutine, regardless of priority, once.
313
314Returns true if at least one coroutine switch has happened.
315
229=item terminate [arg...] 316=item terminate [arg...]
230 317
231Terminates 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.
232 325
233=cut 326=cut
234 327
235sub terminate { 328sub terminate {
236 $current->cancel (@_); 329 $current->cancel (@_);
330}
331
332sub killall {
333 for (Coro::State::list) {
334 $_->cancel
335 if $_ != $current && UNIVERSAL::isa $_, "Coro";
336 }
237} 337}
238 338
239=back 339=back
240 340
241# dynamic methods 341# dynamic methods
251Create 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
252automatically terminates as if C<terminate> with the returned values were 352automatically terminates as if C<terminate> with the returned values were
253called. 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
254by calling the ready method. 354by calling the ready method.
255 355
256Calling 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.
257 358
258=cut 359=cut
259 360
260sub _new_coro { 361sub _run_coro {
261 terminate &{+shift}; 362 terminate &{+shift};
262} 363}
263 364
264sub new { 365sub new {
265 my $class = shift; 366 my $class = shift;
266 367
267 $class->SUPER::new (\&_new_coro, @_) 368 $class->SUPER::new (\&_run_coro, @_)
268} 369}
269 370
270=item $success = $coroutine->ready 371=item $success = $coroutine->ready
271 372
272Put the given coroutine into the ready queue (according to it's priority) 373Put the given coroutine into the ready queue (according to it's priority)
278Return wether the coroutine is currently the ready queue or not, 379Return wether the coroutine is currently the ready queue or not,
279 380
280=item $coroutine->cancel (arg...) 381=item $coroutine->cancel (arg...)
281 382
282Terminates the given coroutine and makes it return the given arguments as 383Terminates the given coroutine and makes it return the given arguments as
283status (default: the empty list). 384status (default: the empty list). Never returns if the coroutine is the
385current coroutine.
284 386
285=cut 387=cut
286 388
287sub cancel { 389sub cancel {
288 my $self = shift; 390 my $self = shift;
289 $self->{status} = [@_]; 391 $self->{_status} = [@_];
392
393 if ($current == $self) {
290 push @destroy, $self; 394 push @destroy, $self;
291 $manager->ready; 395 $manager->ready;
292 &schedule if $current == $self; 396 &schedule while 1;
397 } else {
398 $self->_cancel;
399 }
293} 400}
294 401
295=item $coroutine->join 402=item $coroutine->join
296 403
297Wait until the coroutine terminates and return any values given to the 404Wait until the coroutine terminates and return any values given to the
298C<terminate> or C<cancel> functions. C<join> can be called multiple times 405C<terminate> or C<cancel> functions. C<join> can be called concurrently
299from multiple coroutine. 406from multiple coroutines.
300 407
301=cut 408=cut
302 409
303sub join { 410sub join {
304 my $self = shift; 411 my $self = shift;
412
305 unless ($self->{status}) { 413 unless ($self->{_status}) {
306 push @{$self->{join}}, $current; 414 my $current = $current;
307 &schedule; 415
416 push @{$self->{_on_destroy}}, sub {
417 $current->ready;
418 undef $current;
419 };
420
421 &schedule while $current;
308 } 422 }
423
309 wantarray ? @{$self->{status}} : $self->{status}[0]; 424 wantarray ? @{$self->{_status}} : $self->{_status}[0];
425}
426
427=item $coroutine->on_destroy (\&cb)
428
429Registers a callback that is called when this coroutine gets destroyed,
430but before it is joined. The callback gets passed the terminate arguments,
431if any.
432
433=cut
434
435sub on_destroy {
436 my ($self, $cb) = @_;
437
438 push @{ $self->{_on_destroy} }, $cb;
310} 439}
311 440
312=item $oldprio = $coroutine->prio ($newprio) 441=item $oldprio = $coroutine->prio ($newprio)
313 442
314Sets (or gets, if the argument is missing) the priority of the 443Sets (or gets, if the argument is missing) the priority of the
339=item $olddesc = $coroutine->desc ($newdesc) 468=item $olddesc = $coroutine->desc ($newdesc)
340 469
341Sets (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
342coroutine. 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.
343 472
473This method simply sets the C<< $coroutine->{desc} >> member to the given string. You
474can modify this member directly if you wish.
475
476=item $coroutine->throw ([$scalar])
477
478If C<$throw> is specified and defined, it will be thrown as an exception
479inside the coroutine at the next convinient point in time (usually after
480it gains control at the next schedule/transfer/cede). Otherwise clears the
481exception object.
482
483The exception object will be thrown "as is" with the specified scalar in
484C<$@>, i.e. if it is a string, no line number or newline will be appended
485(unlike with C<die>).
486
487This can be used as a softer means than C<cancel> to ask a coroutine to
488end itself, although there is no guarentee that the exception will lead to
489termination, and if the exception isn't caught it might well end the whole
490program.
491
344=cut 492=cut
345 493
346sub desc { 494sub desc {
347 my $old = $_[0]{desc}; 495 my $old = $_[0]{desc};
348 $_[0]{desc} = $_[1] if @_ > 1; 496 $_[0]{desc} = $_[1] if @_ > 1;
349 $old; 497 $old;
350} 498}
351 499
352=back 500=back
353 501
354=head2 UTILITY FUNCTIONS 502=head2 GLOBAL FUNCTIONS
355 503
356=over 4 504=over 4
505
506=item Coro::nready
507
508Returns the number of coroutines that are currently in the ready state,
509i.e. that can be switched to. The value C<0> means that the only runnable
510coroutine is the currently running one, so C<cede> would have no effect,
511and C<schedule> would cause a deadlock unless there is an idle handler
512that wakes up some coroutines.
513
514=item my $guard = Coro::guard { ... }
515
516This creates and returns a guard object. Nothing happens until the object
517gets destroyed, in which case the codeblock given as argument will be
518executed. This is useful to free locks or other resources in case of a
519runtime error or when the coroutine gets canceled, as in both cases the
520guard block will be executed. The guard object supports only one method,
521C<< ->cancel >>, which will keep the codeblock from being executed.
522
523Example: set some flag and clear it again when the coroutine gets canceled
524or the function returns:
525
526 sub do_something {
527 my $guard = Coro::guard { $busy = 0 };
528 $busy = 1;
529
530 # do something that requires $busy to be true
531 }
532
533=cut
534
535sub guard(&) {
536 bless \(my $cb = $_[0]), "Coro::guard"
537}
538
539sub Coro::guard::cancel {
540 ${$_[0]} = sub { };
541}
542
543sub Coro::guard::DESTROY {
544 ${$_[0]}->();
545}
546
357 547
358=item unblock_sub { ... } 548=item unblock_sub { ... }
359 549
360This utility function takes a BLOCK or code reference and "unblocks" it, 550This utility function takes a BLOCK or code reference and "unblocks" it,
361returning the new coderef. This means that the new coderef will return 551returning the new coderef. This means that the new coderef will return
362immediately without blocking, returning nothing, while the original code 552immediately without blocking, returning nothing, while the original code
363ref will be called (with parameters) from within its own coroutine. 553ref will be called (with parameters) from within its own coroutine.
364 554
365The reason this fucntion exists is that many event libraries (such as the 555The reason this function exists is that many event libraries (such as the
366venerable L<Event|Event> module) are not coroutine-safe (a weaker form 556venerable L<Event|Event> module) are not coroutine-safe (a weaker form
367of thread-safety). This means you must not block within event callbacks, 557of thread-safety). This means you must not block within event callbacks,
368otherwise you might suffer from crashes or worse. 558otherwise you might suffer from crashes or worse.
369 559
370This function allows your callbacks to block by executing them in another 560This function allows your callbacks to block by executing them in another
375In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when 565In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
376creating event callbacks that want to block. 566creating event callbacks that want to block.
377 567
378=cut 568=cut
379 569
380our @unblock_pool;
381our @unblock_queue; 570our @unblock_queue;
382our $UNBLOCK_POOL_SIZE = 2;
383 571
384sub unblock_handler_ { 572# we create a special coro because we want to cede,
385 while () { 573# to reduce pressure on the coro pool (because most callbacks
386 my ($cb, @arg) = @{ delete $Coro::current->{arg} }; 574# return immediately and can be reused) and because we cannot cede
387 $cb->(@arg); 575# inside an event callback.
388
389 last if @unblock_pool >= $UNBLOCK_POOL_SIZE;
390 push @unblock_pool, $Coro::current;
391 schedule;
392 }
393}
394
395our $unblock_scheduler = async { 576our $unblock_scheduler = new Coro sub {
396 while () { 577 while () {
397 while (my $cb = pop @unblock_queue) { 578 while (my $cb = pop @unblock_queue) {
398 my $handler = (pop @unblock_pool or new Coro \&unblock_handler_); 579 # this is an inlined copy of async_pool
399 $handler->{arg} = $cb; 580 my $coro = (pop @async_pool) || new Coro \&pool_handler;
581
582 $coro->{_invoke} = $cb;
400 $handler->ready; 583 $coro->ready;
401 cede; 584 cede; # for short-lived callbacks, this reduces pressure on the coro pool
402 } 585 }
403 586 schedule; # sleep well
404 schedule;
405 } 587 }
406}; 588};
589$unblock_scheduler->desc ("[unblock_sub scheduler]");
407 590
408sub unblock_sub(&) { 591sub unblock_sub(&) {
409 my $cb = shift; 592 my $cb = shift;
410 593
411 sub { 594 sub {
412 push @unblock_queue, [$cb, @_]; 595 unshift @unblock_queue, [$cb, @_];
413 $unblock_scheduler->ready; 596 $unblock_scheduler->ready;
414 } 597 }
415} 598}
416 599
417=back 600=back
424 607
425 - you must make very sure that no coro is still active on global 608 - you must make very sure that no coro is still active on global
426 destruction. very bad things might happen otherwise (usually segfaults). 609 destruction. very bad things might happen otherwise (usually segfaults).
427 610
428 - this module is not thread-safe. You should only ever use this module 611 - this module is not thread-safe. You should only ever use this module
429 from the same thread (this requirement might be losened in the future 612 from the same thread (this requirement might be loosened in the future
430 to allow per-thread schedulers, but Coro::State does not yet allow 613 to allow per-thread schedulers, but Coro::State does not yet allow
431 this). 614 this).
432 615
433=head1 SEE ALSO 616=head1 SEE ALSO
434 617
435Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>. 618Support/Utility: L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.
436 619
437Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>. 620Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
438 621
439Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>. 622Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.
440 623

Diff Legend

Removed lines
+ Added lines
< Changed lines
> Changed lines