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Revision 1.102 by root, Fri Dec 29 11:37:49 2006 UTC vs.
Revision 1.180 by root, Fri Apr 25 04:28:50 2008 UTC

2 2
3Coro - coroutine process abstraction 3Coro - coroutine process abstraction
4 4
5=head1 SYNOPSIS 5=head1 SYNOPSIS
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 };
12 15 print "1\n";
13 # alternatively create an async coroutine like this: 16 cede; # yield to coroutine
14 17 print "3\n";
15 sub some_func : Coro { 18 cede; # and again
16 # some more async code 19
17 } 20 # use locking
18 21 my $lock = new Coro::Semaphore;
19 cede; 22 my $locked;
23
24 $lock->down;
25 $locked = 1;
26 $lock->up;
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 $VERSION = 4.6;
56 63
57our @EXPORT = qw(async cede schedule terminate current unblock_sub); 64our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
58our %EXPORT_TAGS = ( 65our %EXPORT_TAGS = (
59 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], 66 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
60); 67);
61our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready)); 68our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
62 69
63{
64 my @async;
65 my $init;
66
67 # this way of handling attributes simply is NOT scalable ;()
68 sub import {
69 no strict 'refs';
70
71 Coro->export_to_level (1, @_);
72
73 my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
74 *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
75 my ($package, $ref) = (shift, shift);
76 my @attrs;
77 for (@_) {
78 if ($_ eq "Coro") {
79 push @async, $ref;
80 unless ($init++) {
81 eval q{
82 sub INIT {
83 &async(pop @async) while @async;
84 }
85 };
86 }
87 } else {
88 push @attrs, $_;
89 }
90 }
91 return $old ? $old->($package, $ref, @attrs) : @attrs;
92 };
93 }
94
95}
96
97=over 4 70=over 4
98 71
99=item $main 72=item $main
100 73
101This coroutine represents the main program. 74This coroutine represents the main program.
108 81
109The current coroutine (the last coroutine switched to). The initial value 82The current coroutine (the last coroutine switched to). The initial value
110is C<$main> (of course). 83is C<$main> (of course).
111 84
112This variable is B<strictly> I<read-only>. It is provided for performance 85This variable is B<strictly> I<read-only>. It is provided for performance
113reasons. If performance is not essentiel you are encouraged to use the 86reasons. If performance is not essential you are encouraged to use the
114C<Coro::current> function instead. 87C<Coro::current> function instead.
115 88
116=cut 89=cut
117 90
91$main->{desc} = "[main::]";
92
118# maybe some other module used Coro::Specific before... 93# maybe some other module used Coro::Specific before...
119$main->{specific} = $current->{specific} 94$main->{_specific} = $current->{_specific}
120 if $current; 95 if $current;
121 96
122_set_current $main; 97_set_current $main;
123 98
124sub current() { $current } 99sub current() { $current }
132This hook is overwritten by modules such as C<Coro::Timer> and 107This hook is overwritten by modules such as C<Coro::Timer> and
133C<Coro::Event> to wait on an external event that hopefully wake up a 108C<Coro::Event> to wait on an external event that hopefully wake up a
134coroutine so the scheduler can run it. 109coroutine so the scheduler can run it.
135 110
136Please note that if your callback recursively invokes perl (e.g. for event 111Please note that if your callback recursively invokes perl (e.g. for event
137handlers), then it must be prepared to be called recursively. 112handlers), then it must be prepared to be called recursively itself.
138 113
139=cut 114=cut
140 115
141$idle = sub { 116$idle = sub {
142 require Carp; 117 require Carp;
143 Carp::croak ("FATAL: deadlock detected"); 118 Carp::croak ("FATAL: deadlock detected");
144}; 119};
145 120
121sub _cancel {
122 my ($self) = @_;
123
124 # free coroutine data and mark as destructed
125 $self->_destroy
126 or return;
127
128 # call all destruction callbacks
129 $_->(@{$self->{_status}})
130 for @{(delete $self->{_on_destroy}) || []};
131}
132
146# this coroutine is necessary because a coroutine 133# this coroutine is necessary because a coroutine
147# cannot destroy itself. 134# cannot destroy itself.
148my @destroy; 135my @destroy;
136my $manager;
137
149my $manager; $manager = new Coro sub { 138$manager = new Coro sub {
150 while () { 139 while () {
151 # by overwriting the state object with the manager we destroy it 140 (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) { 141 while @destroy;
157 my $coro = pop @destroy;
158 142
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; 143 &schedule;
171 } 144 }
172}; 145};
173 146$manager->desc ("[coro manager]");
174# static methods. not really. 147$manager->prio (PRIO_MAX);
175 148
176=back 149=back
177 150
178=head2 STATIC METHODS 151=head2 STATIC METHODS
179 152
185 158
186Create a new asynchronous coroutine and return it's coroutine object 159Create a new asynchronous coroutine and return it's coroutine object
187(usually unused). When the sub returns the new coroutine is automatically 160(usually unused). When the sub returns the new coroutine is automatically
188terminated. 161terminated.
189 162
190Calling C<exit> in a coroutine will not work correctly, so do not do that. 163See the C<Coro::State::new> constructor for info about the coroutine
164environment in which coroutines run.
191 165
192When the coroutine dies, the program will exit, just as in the main 166Calling C<exit> in a coroutine will do the same as calling exit outside
193program. 167the coroutine. Likewise, when the coroutine dies, the program will exit,
168just as it would in the main program.
194 169
195 # create a new coroutine that just prints its arguments 170 # create a new coroutine that just prints its arguments
196 async { 171 async {
197 print "@_\n"; 172 print "@_\n";
198 } 1,2,3,4; 173 } 1,2,3,4;
199 174
200=cut 175=cut
201 176
202sub async(&@) { 177sub async(&@) {
203 my $pid = new Coro @_; 178 my $coro = new Coro @_;
204 $pid->ready; 179 $coro->ready;
205 $pid 180 $coro
181}
182
183=item async_pool { ... } [@args...]
184
185Similar to C<async>, but uses a coroutine pool, so you should not call
186terminate or join (although you are allowed to), and you get a coroutine
187that might have executed other code already (which can be good or bad :).
188
189Also, the block is executed in an C<eval> context and a warning will be
190issued in case of an exception instead of terminating the program, as
191C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
192will not work in the expected way, unless you call terminate or cancel,
193which somehow defeats the purpose of pooling.
194
195The priority will be reset to C<0> after each job, tracing will be
196disabled, the description will be reset and the default output filehandle
197gets restored, so you can change alkl these. Otherwise the coroutine will
198be re-used "as-is": most notably if you change other per-coroutine global
199stuff such as C<$/> you need to revert that change, which is most simply
200done by using local as in C< local $/ >.
201
202The pool size is limited to 8 idle coroutines (this can be adjusted by
203changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
204required.
205
206If you are concerned about pooled coroutines growing a lot because a
207single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
208{ terminate }> once per second or so to slowly replenish the pool. In
209addition to that, when the stacks used by a handler grows larger than 16kb
210(adjustable with $Coro::POOL_RSS) it will also exit.
211
212=cut
213
214our $POOL_SIZE = 8;
215our $POOL_RSS = 16 * 1024;
216our @async_pool;
217
218sub pool_handler {
219 my $cb;
220
221 while () {
222 eval {
223 while () {
224 _pool_1 $cb;
225 &$cb;
226 _pool_2 $cb;
227 &schedule;
228 }
229 };
230
231 last if $@ eq "\3async_pool terminate\2\n";
232 warn $@ if $@;
233 }
234}
235
236sub async_pool(&@) {
237 # this is also inlined into the unlock_scheduler
238 my $coro = (pop @async_pool) || new Coro \&pool_handler;
239
240 $coro->{_invoke} = [@_];
241 $coro->ready;
242
243 $coro
206} 244}
207 245
208=item schedule 246=item schedule
209 247
210Calls the scheduler. Please note that the current coroutine will not be put 248Calls the scheduler. Please note that the current coroutine will not be put
223 # wake up sleeping coroutine 261 # wake up sleeping coroutine
224 $current->ready; 262 $current->ready;
225 undef $current; 263 undef $current;
226 }; 264 };
227 265
228 # call schedule until event occured. 266 # call schedule until event occurred.
229 # in case we are woken up for other reasons 267 # in case we are woken up for other reasons
230 # (current still defined), loop. 268 # (current still defined), loop.
231 Coro::schedule while $current; 269 Coro::schedule while $current;
232 } 270 }
233 271
244 282
245=item terminate [arg...] 283=item terminate [arg...]
246 284
247Terminates the current coroutine with the given status values (see L<cancel>). 285Terminates the current coroutine with the given status values (see L<cancel>).
248 286
287=item killall
288
289Kills/terminates/cancels all coroutines except the currently running
290one. This is useful after a fork, either in the child or the parent, as
291usually only one of them should inherit the running coroutines.
292
249=cut 293=cut
250 294
251sub terminate { 295sub terminate {
252 $current->cancel (@_); 296 $current->cancel (@_);
253} 297}
254 298
299sub killall {
300 for (Coro::State::list) {
301 $_->cancel
302 if $_ != $current && UNIVERSAL::isa $_, "Coro";
303 }
304}
305
255=back 306=back
256
257# dynamic methods
258 307
259=head2 COROUTINE METHODS 308=head2 COROUTINE METHODS
260 309
261These are the methods you can call on coroutine objects. 310These are the methods you can call on coroutine objects.
262 311
267Create a new coroutine and return it. When the sub returns the coroutine 316Create a new coroutine and return it. When the sub returns the coroutine
268automatically terminates as if C<terminate> with the returned values were 317automatically terminates as if C<terminate> with the returned values were
269called. To make the coroutine run you must first put it into the ready queue 318called. To make the coroutine run you must first put it into the ready queue
270by calling the ready method. 319by calling the ready method.
271 320
272Calling C<exit> in a coroutine will not work correctly, so do not do that. 321See C<async> and C<Coro::State::new> for additional info about the
322coroutine environment.
273 323
274=cut 324=cut
275 325
276sub _run_coro { 326sub _run_coro {
277 terminate &{+shift}; 327 terminate &{+shift};
294Return wether the coroutine is currently the ready queue or not, 344Return wether the coroutine is currently the ready queue or not,
295 345
296=item $coroutine->cancel (arg...) 346=item $coroutine->cancel (arg...)
297 347
298Terminates the given coroutine and makes it return the given arguments as 348Terminates the given coroutine and makes it return the given arguments as
299status (default: the empty list). 349status (default: the empty list). Never returns if the coroutine is the
350current coroutine.
300 351
301=cut 352=cut
302 353
303sub cancel { 354sub cancel {
304 my $self = shift; 355 my $self = shift;
305 $self->{status} = [@_]; 356 $self->{_status} = [@_];
357
358 if ($current == $self) {
306 push @destroy, $self; 359 push @destroy, $self;
307 $manager->ready; 360 $manager->ready;
308 &schedule if $current == $self; 361 &schedule while 1;
362 } else {
363 $self->_cancel;
364 }
309} 365}
310 366
311=item $coroutine->join 367=item $coroutine->join
312 368
313Wait until the coroutine terminates and return any values given to the 369Wait until the coroutine terminates and return any values given to the
314C<terminate> or C<cancel> functions. C<join> can be called multiple times 370C<terminate> or C<cancel> functions. C<join> can be called concurrently
315from multiple coroutine. 371from multiple coroutines.
316 372
317=cut 373=cut
318 374
319sub join { 375sub join {
320 my $self = shift; 376 my $self = shift;
377
321 unless ($self->{status}) { 378 unless ($self->{_status}) {
322 push @{$self->{join}}, $current; 379 my $current = $current;
323 &schedule; 380
381 push @{$self->{_on_destroy}}, sub {
382 $current->ready;
383 undef $current;
384 };
385
386 &schedule while $current;
324 } 387 }
388
325 wantarray ? @{$self->{status}} : $self->{status}[0]; 389 wantarray ? @{$self->{_status}} : $self->{_status}[0];
326} 390}
327 391
328=item $coroutine->on_destroy (\&cb) 392=item $coroutine->on_destroy (\&cb)
329 393
330Registers a callback that is called when this coroutine gets destroyed, 394Registers a callback that is called when this coroutine gets destroyed,
334=cut 398=cut
335 399
336sub on_destroy { 400sub on_destroy {
337 my ($self, $cb) = @_; 401 my ($self, $cb) = @_;
338 402
339 push @{ $self->{destroy_cb} }, $cb; 403 push @{ $self->{_on_destroy} }, $cb;
340} 404}
341 405
342=item $oldprio = $coroutine->prio ($newprio) 406=item $oldprio = $coroutine->prio ($newprio)
343 407
344Sets (or gets, if the argument is missing) the priority of the 408Sets (or gets, if the argument is missing) the priority of the
369=item $olddesc = $coroutine->desc ($newdesc) 433=item $olddesc = $coroutine->desc ($newdesc)
370 434
371Sets (or gets in case the argument is missing) the description for this 435Sets (or gets in case the argument is missing) the description for this
372coroutine. This is just a free-form string you can associate with a coroutine. 436coroutine. This is just a free-form string you can associate with a coroutine.
373 437
438This method simply sets the C<< $coroutine->{desc} >> member to the given string. You
439can modify this member directly if you wish.
440
441=item $coroutine->throw ([$scalar])
442
443If C<$throw> is specified and defined, it will be thrown as an exception
444inside the coroutine at the next convinient point in time (usually after
445it gains control at the next schedule/transfer/cede). Otherwise clears the
446exception object.
447
448The exception object will be thrown "as is" with the specified scalar in
449C<$@>, i.e. if it is a string, no line number or newline will be appended
450(unlike with C<die>).
451
452This can be used as a softer means than C<cancel> to ask a coroutine to
453end itself, although there is no guarentee that the exception will lead to
454termination, and if the exception isn't caught it might well end the whole
455program.
456
374=cut 457=cut
375 458
376sub desc { 459sub desc {
377 my $old = $_[0]{desc}; 460 my $old = $_[0]{desc};
378 $_[0]{desc} = $_[1] if @_ > 1; 461 $_[0]{desc} = $_[1] if @_ > 1;
386=over 4 469=over 4
387 470
388=item Coro::nready 471=item Coro::nready
389 472
390Returns the number of coroutines that are currently in the ready state, 473Returns the number of coroutines that are currently in the ready state,
391i.e. that can be swicthed to. The value C<0> means that the only runnable 474i.e. that can be switched to. The value C<0> means that the only runnable
392coroutine is the currently running one, so C<cede> would have no effect, 475coroutine is the currently running one, so C<cede> would have no effect,
393and C<schedule> would cause a deadlock unless there is an idle handler 476and C<schedule> would cause a deadlock unless there is an idle handler
394that wakes up some coroutines. 477that wakes up some coroutines.
478
479=item my $guard = Coro::guard { ... }
480
481This creates and returns a guard object. Nothing happens until the object
482gets destroyed, in which case the codeblock given as argument will be
483executed. This is useful to free locks or other resources in case of a
484runtime error or when the coroutine gets canceled, as in both cases the
485guard block will be executed. The guard object supports only one method,
486C<< ->cancel >>, which will keep the codeblock from being executed.
487
488Example: set some flag and clear it again when the coroutine gets canceled
489or the function returns:
490
491 sub do_something {
492 my $guard = Coro::guard { $busy = 0 };
493 $busy = 1;
494
495 # do something that requires $busy to be true
496 }
497
498=cut
499
500sub guard(&) {
501 bless \(my $cb = $_[0]), "Coro::guard"
502}
503
504sub Coro::guard::cancel {
505 ${$_[0]} = sub { };
506}
507
508sub Coro::guard::DESTROY {
509 ${$_[0]}->();
510}
511
395 512
396=item unblock_sub { ... } 513=item unblock_sub { ... }
397 514
398This utility function takes a BLOCK or code reference and "unblocks" it, 515This utility function takes a BLOCK or code reference and "unblocks" it,
399returning the new coderef. This means that the new coderef will return 516returning the new coderef. This means that the new coderef will return
400immediately without blocking, returning nothing, while the original code 517immediately without blocking, returning nothing, while the original code
401ref will be called (with parameters) from within its own coroutine. 518ref will be called (with parameters) from within its own coroutine.
402 519
403The reason this fucntion exists is that many event libraries (such as the 520The reason this function exists is that many event libraries (such as the
404venerable L<Event|Event> module) are not coroutine-safe (a weaker form 521venerable L<Event|Event> module) are not coroutine-safe (a weaker form
405of thread-safety). This means you must not block within event callbacks, 522of thread-safety). This means you must not block within event callbacks,
406otherwise you might suffer from crashes or worse. 523otherwise you might suffer from crashes or worse.
407 524
408This function allows your callbacks to block by executing them in another 525This function allows your callbacks to block by executing them in another
413In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when 530In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
414creating event callbacks that want to block. 531creating event callbacks that want to block.
415 532
416=cut 533=cut
417 534
418our @unblock_pool;
419our @unblock_queue; 535our @unblock_queue;
420our $UNBLOCK_POOL_SIZE = 2;
421 536
422sub unblock_handler_ { 537# we create a special coro because we want to cede,
423 while () { 538# to reduce pressure on the coro pool (because most callbacks
424 my ($cb, @arg) = @{ delete $Coro::current->{arg} }; 539# return immediately and can be reused) and because we cannot cede
425 $cb->(@arg); 540# inside an event callback.
426
427 last if @unblock_pool >= $UNBLOCK_POOL_SIZE;
428 push @unblock_pool, $Coro::current;
429 schedule;
430 }
431}
432
433our $unblock_scheduler = async { 541our $unblock_scheduler = new Coro sub {
434 while () { 542 while () {
435 while (my $cb = pop @unblock_queue) { 543 while (my $cb = pop @unblock_queue) {
436 my $handler = (pop @unblock_pool or new Coro \&unblock_handler_); 544 # this is an inlined copy of async_pool
437 $handler->{arg} = $cb; 545 my $coro = (pop @async_pool) || new Coro \&pool_handler;
546
547 $coro->{_invoke} = $cb;
438 $handler->ready; 548 $coro->ready;
439 cede; 549 cede; # for short-lived callbacks, this reduces pressure on the coro pool
440 } 550 }
441 551 schedule; # sleep well
442 schedule;
443 } 552 }
444}; 553};
554$unblock_scheduler->desc ("[unblock_sub scheduler]");
445 555
446sub unblock_sub(&) { 556sub unblock_sub(&) {
447 my $cb = shift; 557 my $cb = shift;
448 558
449 sub { 559 sub {
450 push @unblock_queue, [$cb, @_]; 560 unshift @unblock_queue, [$cb, @_];
451 $unblock_scheduler->ready; 561 $unblock_scheduler->ready;
452 } 562 }
453} 563}
454 564
455=back 565=back
462 572
463 - you must make very sure that no coro is still active on global 573 - you must make very sure that no coro is still active on global
464 destruction. very bad things might happen otherwise (usually segfaults). 574 destruction. very bad things might happen otherwise (usually segfaults).
465 575
466 - this module is not thread-safe. You should only ever use this module 576 - this module is not thread-safe. You should only ever use this module
467 from the same thread (this requirement might be losened in the future 577 from the same thread (this requirement might be loosened in the future
468 to allow per-thread schedulers, but Coro::State does not yet allow 578 to allow per-thread schedulers, but Coro::State does not yet allow
469 this). 579 this).
470 580
471=head1 SEE ALSO 581=head1 SEE ALSO
472 582
583Lower level Configuration, Coroutine Environment: L<Coro::State>.
584
585Debugging: L<Coro::Debug>.
586
473Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>. 587Support/Utility: L<Coro::Specific>, L<Coro::Util>.
474 588
475Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>. 589Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
476 590
477Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>. 591Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>.
478 592
593Compatibility: L<Coro::LWP>, L<Coro::Storable>, L<Coro::Select>.
594
479Embedding: L<Coro:MakeMaker> 595Embedding: L<Coro::MakeMaker>.
480 596
481=head1 AUTHOR 597=head1 AUTHOR
482 598
483 Marc Lehmann <schmorp@schmorp.de> 599 Marc Lehmann <schmorp@schmorp.de>
484 http://home.schmorp.de/ 600 http://home.schmorp.de/

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