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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 to 30This module collection manages coroutines. Coroutines are similar
24threads but don't run in parallel. 31to threads but don't run in parallel at the same time even on SMP
32machines. The specific flavor of coroutine used in this module also
33guarantees you that it will not switch between coroutines unless
34necessary, at easily-identified points in your program, so locking and
35parallel access are rarely an issue, making coroutine programming much
36safer than threads programming.
25 37
38(Perl, however, does not natively support real threads but instead does a
39very slow and memory-intensive emulation of processes using threads. This
40is a performance win on Windows machines, and a loss everywhere else).
41
26In this module, coroutines are defined as "callchain + lexical variables 42In this module, coroutines are defined as "callchain + lexical variables +
27+ @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own 43@_ + $_ + $@ + $/ + 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 44its own set of lexicals and its own set of perls most important global
29important global variables. 45variables (see L<Coro::State> for more configuration).
30 46
31=cut 47=cut
32 48
33package Coro; 49package Coro;
34 50
41 57
42our $idle; # idle handler 58our $idle; # idle handler
43our $main; # main coroutine 59our $main; # main coroutine
44our $current; # current coroutine 60our $current; # current coroutine
45 61
46our $VERSION = '3.01'; 62our $VERSION = '4.1';
47 63
48our @EXPORT = qw(async cede schedule terminate current unblock_sub); 64our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
49our %EXPORT_TAGS = ( 65our %EXPORT_TAGS = (
50 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], 66 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
51); 67);
52our @EXPORT_OK = @{$EXPORT_TAGS{prio}}; 68our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
53 69
54{ 70{
55 my @async; 71 my @async;
56 my $init; 72 my $init;
57 73
99 115
100The current coroutine (the last coroutine switched to). The initial value 116The current coroutine (the last coroutine switched to). The initial value
101is C<$main> (of course). 117is C<$main> (of course).
102 118
103This variable is B<strictly> I<read-only>. It is provided for performance 119This variable is B<strictly> I<read-only>. It is provided for performance
104reasons. If performance is not essentiel you are encouraged to use the 120reasons. If performance is not essential you are encouraged to use the
105C<Coro::current> function instead. 121C<Coro::current> function instead.
106 122
107=cut 123=cut
108 124
125$main->{desc} = "[main::]";
126
109# maybe some other module used Coro::Specific before... 127# maybe some other module used Coro::Specific before...
110$main->{specific} = $current->{specific} 128$main->{_specific} = $current->{_specific}
111 if $current; 129 if $current;
112 130
113_set_current $main; 131_set_current $main;
114 132
115sub current() { $current } 133sub current() { $current }
123This hook is overwritten by modules such as C<Coro::Timer> and 141This hook is overwritten by modules such as C<Coro::Timer> and
124C<Coro::Event> to wait on an external event that hopefully wake up a 142C<Coro::Event> to wait on an external event that hopefully wake up a
125coroutine so the scheduler can run it. 143coroutine so the scheduler can run it.
126 144
127Please note that if your callback recursively invokes perl (e.g. for event 145Please note that if your callback recursively invokes perl (e.g. for event
128handlers), then it must be prepared to be called recursively. 146handlers), then it must be prepared to be called recursively itself.
129 147
130=cut 148=cut
131 149
132$idle = sub { 150$idle = sub {
133 require Carp; 151 require Carp;
134 Carp::croak ("FATAL: deadlock detected"); 152 Carp::croak ("FATAL: deadlock detected");
135}; 153};
136 154
155sub _cancel {
156 my ($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
137# this coroutine is necessary because a coroutine 167# this coroutine is necessary because a coroutine
138# cannot destroy itself. 168# cannot destroy itself.
139my @destroy; 169my @destroy;
170my $manager;
171
140my $manager; $manager = new Coro sub { 172$manager = new Coro sub {
141 while () { 173 while () {
142 # by overwriting the state object with the manager we destroy it 174 (shift @destroy)->_cancel
143 # while still being able to schedule this coroutine (in case it has
144 # been readied multiple times. this is harmless since the manager
145 # can be called as many times as neccessary and will always
146 # remove itself from the runqueue
147 while (@destroy) { 175 while @destroy;
148 my $coro = pop @destroy;
149 $coro->{status} ||= [];
150 $_->ready for @{delete $coro->{join} || []};
151 176
152 # the next line destroys the coro state, but keeps the
153 # coroutine itself intact (we basically make it a zombie
154 # coroutine that always runs the manager thread, so it's possible
155 # to transfer() to this coroutine).
156 $coro->_clone_state_from ($manager);
157 }
158 &schedule; 177 &schedule;
159 } 178 }
160}; 179};
180$manager->desc ("[coro manager]");
181$manager->prio (PRIO_MAX);
161 182
162# static methods. not really. 183# static methods. not really.
163 184
164=back 185=back
165 186
173 194
174Create a new asynchronous coroutine and return it's coroutine object 195Create a new asynchronous coroutine and return it's coroutine object
175(usually unused). When the sub returns the new coroutine is automatically 196(usually unused). When the sub returns the new coroutine is automatically
176terminated. 197terminated.
177 198
178Calling 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.
179 201
180When 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
181program. 203the coroutine. Likewise, when the coroutine dies, the program will exit,
204just as it would in the main program.
182 205
183 # create a new coroutine that just prints its arguments 206 # create a new coroutine that just prints its arguments
184 async { 207 async {
185 print "@_\n"; 208 print "@_\n";
186 } 1,2,3,4; 209 } 1,2,3,4;
187 210
188=cut 211=cut
189 212
190sub async(&@) { 213sub async(&@) {
191 my $pid = new Coro @_; 214 my $coro = new Coro @_;
192 $pid->ready; 215 $coro->ready;
193 $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
194} 280}
195 281
196=item schedule 282=item schedule
197 283
198Calls 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
211 # wake up sleeping coroutine 297 # wake up sleeping coroutine
212 $current->ready; 298 $current->ready;
213 undef $current; 299 undef $current;
214 }; 300 };
215 301
216 # call schedule until event occured. 302 # call schedule until event occurred.
217 # in case we are woken up for other reasons 303 # in case we are woken up for other reasons
218 # (current still defined), loop. 304 # (current still defined), loop.
219 Coro::schedule while $current; 305 Coro::schedule while $current;
220 } 306 }
221 307
223 309
224"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
225ready 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
226current "timeslice" to other coroutines of the same or higher priority. 312current "timeslice" to other coroutines of the same or higher priority.
227 313
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
228=item terminate [arg...] 323=item terminate [arg...]
229 324
230Terminates 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.
231 332
232=cut 333=cut
233 334
234sub terminate { 335sub terminate {
235 $current->cancel (@_); 336 $current->cancel (@_);
337}
338
339sub killall {
340 for (Coro::State::list) {
341 $_->cancel
342 if $_ != $current && UNIVERSAL::isa $_, "Coro";
343 }
236} 344}
237 345
238=back 346=back
239 347
240# dynamic methods 348# dynamic methods
250Create 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
251automatically terminates as if C<terminate> with the returned values were 359automatically terminates as if C<terminate> with the returned values were
252called. 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
253by calling the ready method. 361by calling the ready method.
254 362
255Calling 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.
256 365
257=cut 366=cut
258 367
259sub _run_coro { 368sub _run_coro {
260 terminate &{+shift}; 369 terminate &{+shift};
277Return wether the coroutine is currently the ready queue or not, 386Return wether the coroutine is currently the ready queue or not,
278 387
279=item $coroutine->cancel (arg...) 388=item $coroutine->cancel (arg...)
280 389
281Terminates the given coroutine and makes it return the given arguments as 390Terminates the given coroutine and makes it return the given arguments as
282status (default: the empty list). 391status (default: the empty list). Never returns if the coroutine is the
392current coroutine.
283 393
284=cut 394=cut
285 395
286sub cancel { 396sub cancel {
287 my $self = shift; 397 my $self = shift;
288 $self->{status} = [@_]; 398 $self->{_status} = [@_];
399
400 if ($current == $self) {
289 push @destroy, $self; 401 push @destroy, $self;
290 $manager->ready; 402 $manager->ready;
291 &schedule if $current == $self; 403 &schedule while 1;
404 } else {
405 $self->_cancel;
406 }
292} 407}
293 408
294=item $coroutine->join 409=item $coroutine->join
295 410
296Wait until the coroutine terminates and return any values given to the 411Wait until the coroutine terminates and return any values given to the
297C<terminate> or C<cancel> functions. C<join> can be called multiple times 412C<terminate> or C<cancel> functions. C<join> can be called concurrently
298from multiple coroutine. 413from multiple coroutines.
299 414
300=cut 415=cut
301 416
302sub join { 417sub join {
303 my $self = shift; 418 my $self = shift;
419
304 unless ($self->{status}) { 420 unless ($self->{_status}) {
305 push @{$self->{join}}, $current; 421 my $current = $current;
306 &schedule; 422
423 push @{$self->{_on_destroy}}, sub {
424 $current->ready;
425 undef $current;
426 };
427
428 &schedule while $current;
307 } 429 }
430
308 wantarray ? @{$self->{status}} : $self->{status}[0]; 431 wantarray ? @{$self->{_status}} : $self->{_status}[0];
432}
433
434=item $coroutine->on_destroy (\&cb)
435
436Registers a callback that is called when this coroutine gets destroyed,
437but before it is joined. The callback gets passed the terminate arguments,
438if any.
439
440=cut
441
442sub on_destroy {
443 my ($self, $cb) = @_;
444
445 push @{ $self->{_on_destroy} }, $cb;
309} 446}
310 447
311=item $oldprio = $coroutine->prio ($newprio) 448=item $oldprio = $coroutine->prio ($newprio)
312 449
313Sets (or gets, if the argument is missing) the priority of the 450Sets (or gets, if the argument is missing) the priority of the
338=item $olddesc = $coroutine->desc ($newdesc) 475=item $olddesc = $coroutine->desc ($newdesc)
339 476
340Sets (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
341coroutine. 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.
342 479
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
343=cut 499=cut
344 500
345sub desc { 501sub desc {
346 my $old = $_[0]{desc}; 502 my $old = $_[0]{desc};
347 $_[0]{desc} = $_[1] if @_ > 1; 503 $_[0]{desc} = $_[1] if @_ > 1;
348 $old; 504 $old;
349} 505}
350 506
351=back 507=back
352 508
353=head2 UTILITY FUNCTIONS 509=head2 GLOBAL FUNCTIONS
354 510
355=over 4 511=over 4
512
513=item Coro::nready
514
515Returns the number of coroutines that are currently in the ready state,
516i.e. that can be switched to. The value C<0> means that the only runnable
517coroutine is the currently running one, so C<cede> would have no effect,
518and C<schedule> would cause a deadlock unless there is an idle handler
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
356 554
357=item unblock_sub { ... } 555=item unblock_sub { ... }
358 556
359This utility function takes a BLOCK or code reference and "unblocks" it, 557This utility function takes a BLOCK or code reference and "unblocks" it,
360returning the new coderef. This means that the new coderef will return 558returning the new coderef. This means that the new coderef will return
361immediately without blocking, returning nothing, while the original code 559immediately without blocking, returning nothing, while the original code
362ref will be called (with parameters) from within its own coroutine. 560ref will be called (with parameters) from within its own coroutine.
363 561
364The 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
365venerable L<Event|Event> module) are not coroutine-safe (a weaker form 563venerable L<Event|Event> module) are not coroutine-safe (a weaker form
366of thread-safety). This means you must not block within event callbacks, 564of thread-safety). This means you must not block within event callbacks,
367otherwise you might suffer from crashes or worse. 565otherwise you might suffer from crashes or worse.
368 566
369This function allows your callbacks to block by executing them in another 567This function allows your callbacks to block by executing them in another
374In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when 572In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
375creating event callbacks that want to block. 573creating event callbacks that want to block.
376 574
377=cut 575=cut
378 576
379our @unblock_pool;
380our @unblock_queue; 577our @unblock_queue;
381our $UNBLOCK_POOL_SIZE = 2;
382 578
383sub unblock_handler_ { 579# we create a special coro because we want to cede,
384 while () { 580# to reduce pressure on the coro pool (because most callbacks
385 my ($cb, @arg) = @{ delete $Coro::current->{arg} }; 581# return immediately and can be reused) and because we cannot cede
386 $cb->(@arg); 582# inside an event callback.
387
388 last if @unblock_pool >= $UNBLOCK_POOL_SIZE;
389 push @unblock_pool, $Coro::current;
390 schedule;
391 }
392}
393
394our $unblock_scheduler = async { 583our $unblock_scheduler = new Coro sub {
395 while () { 584 while () {
396 while (my $cb = pop @unblock_queue) { 585 while (my $cb = pop @unblock_queue) {
397 my $handler = (pop @unblock_pool or new Coro \&unblock_handler_); 586 # this is an inlined copy of async_pool
398 $handler->{arg} = $cb; 587 my $coro = (pop @async_pool) || new Coro \&pool_handler;
588
589 $coro->{_invoke} = $cb;
399 $handler->ready; 590 $coro->ready;
400 cede; 591 cede; # for short-lived callbacks, this reduces pressure on the coro pool
401 } 592 }
402 593 schedule; # sleep well
403 schedule;
404 } 594 }
405}; 595};
596$unblock_scheduler->desc ("[unblock_sub scheduler]");
406 597
407sub unblock_sub(&) { 598sub unblock_sub(&) {
408 my $cb = shift; 599 my $cb = shift;
409 600
410 sub { 601 sub {
411 push @unblock_queue, [$cb, @_]; 602 unshift @unblock_queue, [$cb, @_];
412 $unblock_scheduler->ready; 603 $unblock_scheduler->ready;
413 } 604 }
414} 605}
415 606
416=back 607=back
423 614
424 - 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
425 destruction. very bad things might happen otherwise (usually segfaults). 616 destruction. very bad things might happen otherwise (usually segfaults).
426 617
427 - 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
428 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
429 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
430 this). 621 this).
431 622
432=head1 SEE ALSO 623=head1 SEE ALSO
433 624
625Lower level Configuration, Coroutine Environment: L<Coro::State>.
626
627Debugging: L<Coro::Debug>.
628
434Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>. 629Support/Utility: L<Coro::Specific>, L<Coro::Util>.
435 630
436Locking/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>.
437 632
438Event/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>.
439 634
635Compatibility: L<Coro::LWP>, L<Coro::Storable>, L<Coro::Select>.
636
440Embedding: L<Coro:MakeMaker> 637Embedding: L<Coro:MakeMaker>.
441 638
442=head1 AUTHOR 639=head1 AUTHOR
443 640
444 Marc Lehmann <schmorp@schmorp.de> 641 Marc Lehmann <schmorp@schmorp.de>
445 http://home.schmorp.de/ 642 http://home.schmorp.de/

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