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Revision 1.114 by root, Wed Jan 24 16:22:08 2007 UTC vs.
Revision 1.179 by root, Sat Apr 19 19:06:02 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 = '3.5'; 62our $VERSION = '4.51';
56 63
57our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); 64our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
58our %EXPORT_TAGS = ( 65our %EXPORT_TAGS = (
59 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], 66 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
60); 67);
61our @EXPORT_OK = (@{$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;
149 # free coroutine data and mark as destructed 124 # free coroutine data and mark as destructed
150 $self->_destroy 125 $self->_destroy
151 or return; 126 or return;
152 127
153 # call all destruction callbacks 128 # call all destruction callbacks
154 $_->(@{$self->{status}}) 129 $_->(@{$self->{_status}})
155 for @{(delete $self->{destroy_cb}) || []}; 130 for @{(delete $self->{_on_destroy}) || []};
156} 131}
157 132
158# this coroutine is necessary because a coroutine 133# this coroutine is necessary because a coroutine
159# cannot destroy itself. 134# cannot destroy itself.
160my @destroy; 135my @destroy;
166 while @destroy; 141 while @destroy;
167 142
168 &schedule; 143 &schedule;
169 } 144 }
170}; 145};
171 146$manager->desc ("[coro manager]");
172$manager->prio (PRIO_MAX); 147$manager->prio (PRIO_MAX);
173
174# static methods. not really.
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;
215issued in case of an exception instead of terminating the program, as 190issued in case of an exception instead of terminating the program, as
216C<async> does. As the coroutine is being reused, stuff like C<on_destroy> 191C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
217will not work in the expected way, unless you call terminate or cancel, 192will not work in the expected way, unless you call terminate or cancel,
218which somehow defeats the purpose of pooling. 193which somehow defeats the purpose of pooling.
219 194
220The priority will be reset to C<0> after each job, otherwise the coroutine 195The priority will be reset to C<0> after each job, tracing will be
221will be re-used "as-is". 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 $/ >.
222 201
223The pool size is limited to 8 idle coroutines (this can be adjusted by 202The pool size is limited to 8 idle coroutines (this can be adjusted by
224changing $Coro::POOL_SIZE), and there can be as many non-idle coros as 203changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
225required. 204required.
226 205
227If you are concerned about pooled coroutines growing a lot because a 206If you are concerned about pooled coroutines growing a lot because a
228single C<async_pool> used a lot of stackspace you can e.g. C<async_pool { 207single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
229terminate }> once per second or so to slowly replenish the 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.
230 211
231=cut 212=cut
232 213
233our $POOL_SIZE = 8; 214our $POOL_SIZE = 8;
215our $POOL_RSS = 16 * 1024;
234our @pool; 216our @async_pool;
235 217
236sub pool_handler { 218sub pool_handler {
219 my $cb;
220
237 while () { 221 while () {
238 eval { 222 eval {
239 my ($cb, @arg) = @{ delete $current->{_invoke} or return }; 223 while () {
240 $cb->(@arg); 224 _pool_1 $cb;
225 &$cb;
226 _pool_2 $cb;
227 &schedule;
228 }
241 }; 229 };
230
231 last if $@ eq "\3async_pool terminate\2\n";
242 warn $@ if $@; 232 warn $@ if $@;
243
244 last if @pool >= $POOL_SIZE;
245 push @pool, $current;
246
247 $current->prio (0);
248 schedule;
249 } 233 }
250} 234}
251 235
252sub async_pool(&@) { 236sub async_pool(&@) {
253 # this is also inlined into the unlock_scheduler 237 # this is also inlined into the unlock_scheduler
254 my $coro = (pop @pool or new Coro \&pool_handler); 238 my $coro = (pop @async_pool) || new Coro \&pool_handler;
255 239
256 $coro->{_invoke} = [@_]; 240 $coro->{_invoke} = [@_];
257 $coro->ready; 241 $coro->ready;
258 242
259 $coro 243 $coro
277 # wake up sleeping coroutine 261 # wake up sleeping coroutine
278 $current->ready; 262 $current->ready;
279 undef $current; 263 undef $current;
280 }; 264 };
281 265
282 # call schedule until event occured. 266 # call schedule until event occurred.
283 # in case we are woken up for other reasons 267 # in case we are woken up for other reasons
284 # (current still defined), loop. 268 # (current still defined), loop.
285 Coro::schedule while $current; 269 Coro::schedule while $current;
286 } 270 }
287 271
289 273
290"Cede" to other coroutines. This function puts the current coroutine into the 274"Cede" to other coroutines. This function puts the current coroutine into the
291ready queue and calls C<schedule>, which has the effect of giving up the 275ready queue and calls C<schedule>, which has the effect of giving up the
292current "timeslice" to other coroutines of the same or higher priority. 276current "timeslice" to other coroutines of the same or higher priority.
293 277
294Returns true if at least one coroutine switch has happened.
295
296=item Coro::cede_notself 278=item Coro::cede_notself
297 279
298Works like cede, but is not exported by default and will cede to any 280Works like cede, but is not exported by default and will cede to any
299coroutine, regardless of priority, once. 281coroutine, regardless of priority, once.
300 282
301Returns true if at least one coroutine switch has happened.
302
303=item terminate [arg...] 283=item terminate [arg...]
304 284
305Terminates the current coroutine with the given status values (see L<cancel>). 285Terminates the current coroutine with the given status values (see L<cancel>).
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.
306 292
307=cut 293=cut
308 294
309sub terminate { 295sub terminate {
310 $current->cancel (@_); 296 $current->cancel (@_);
311} 297}
312 298
299sub killall {
300 for (Coro::State::list) {
301 $_->cancel
302 if $_ != $current && UNIVERSAL::isa $_, "Coro";
303 }
304}
305
313=back 306=back
314
315# dynamic methods
316 307
317=head2 COROUTINE METHODS 308=head2 COROUTINE METHODS
318 309
319These are the methods you can call on coroutine objects. 310These are the methods you can call on coroutine objects.
320 311
325Create 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
326automatically terminates as if C<terminate> with the returned values were 317automatically terminates as if C<terminate> with the returned values were
327called. 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
328by calling the ready method. 319by calling the ready method.
329 320
330Calling 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.
331 323
332=cut 324=cut
333 325
334sub _run_coro { 326sub _run_coro {
335 terminate &{+shift}; 327 terminate &{+shift};
359 351
360=cut 352=cut
361 353
362sub cancel { 354sub cancel {
363 my $self = shift; 355 my $self = shift;
364 $self->{status} = [@_]; 356 $self->{_status} = [@_];
365 357
366 if ($current == $self) { 358 if ($current == $self) {
367 push @destroy, $self; 359 push @destroy, $self;
368 $manager->ready; 360 $manager->ready;
369 &schedule while 1; 361 &schedule while 1;
373} 365}
374 366
375=item $coroutine->join 367=item $coroutine->join
376 368
377Wait until the coroutine terminates and return any values given to the 369Wait until the coroutine terminates and return any values given to the
378C<terminate> or C<cancel> functions. C<join> can be called multiple times 370C<terminate> or C<cancel> functions. C<join> can be called concurrently
379from multiple coroutine. 371from multiple coroutines.
380 372
381=cut 373=cut
382 374
383sub join { 375sub join {
384 my $self = shift; 376 my $self = shift;
385 377
386 unless ($self->{status}) { 378 unless ($self->{_status}) {
387 my $current = $current; 379 my $current = $current;
388 380
389 push @{$self->{destroy_cb}}, sub { 381 push @{$self->{_on_destroy}}, sub {
390 $current->ready; 382 $current->ready;
391 undef $current; 383 undef $current;
392 }; 384 };
393 385
394 &schedule while $current; 386 &schedule while $current;
395 } 387 }
396 388
397 wantarray ? @{$self->{status}} : $self->{status}[0]; 389 wantarray ? @{$self->{_status}} : $self->{_status}[0];
398} 390}
399 391
400=item $coroutine->on_destroy (\&cb) 392=item $coroutine->on_destroy (\&cb)
401 393
402Registers a callback that is called when this coroutine gets destroyed, 394Registers a callback that is called when this coroutine gets destroyed,
406=cut 398=cut
407 399
408sub on_destroy { 400sub on_destroy {
409 my ($self, $cb) = @_; 401 my ($self, $cb) = @_;
410 402
411 push @{ $self->{destroy_cb} }, $cb; 403 push @{ $self->{_on_destroy} }, $cb;
412} 404}
413 405
414=item $oldprio = $coroutine->prio ($newprio) 406=item $oldprio = $coroutine->prio ($newprio)
415 407
416Sets (or gets, if the argument is missing) the priority of the 408Sets (or gets, if the argument is missing) the priority of the
441=item $olddesc = $coroutine->desc ($newdesc) 433=item $olddesc = $coroutine->desc ($newdesc)
442 434
443Sets (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
444coroutine. 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.
445 437
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
446=cut 457=cut
447 458
448sub desc { 459sub desc {
449 my $old = $_[0]{desc}; 460 my $old = $_[0]{desc};
450 $_[0]{desc} = $_[1] if @_ > 1; 461 $_[0]{desc} = $_[1] if @_ > 1;
458=over 4 469=over 4
459 470
460=item Coro::nready 471=item Coro::nready
461 472
462Returns the number of coroutines that are currently in the ready state, 473Returns the number of coroutines that are currently in the ready state,
463i.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
464coroutine 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,
465and 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
466that wakes up some coroutines. 477that wakes up some coroutines.
467 478
468=item my $guard = Coro::guard { ... } 479=item my $guard = Coro::guard { ... }
469 480
470This creates and returns a guard object. Nothing happens until the objetc 481This creates and returns a guard object. Nothing happens until the object
471gets destroyed, in which case the codeblock given as argument will be 482gets destroyed, in which case the codeblock given as argument will be
472executed. This is useful to free locks or other resources in case of a 483executed. This is useful to free locks or other resources in case of a
473runtime error or when the coroutine gets canceled, as in both cases the 484runtime error or when the coroutine gets canceled, as in both cases the
474guard block will be executed. The guard object supports only one method, 485guard block will be executed. The guard object supports only one method,
475C<< ->cancel >>, which will keep the codeblock from being executed. 486C<< ->cancel >>, which will keep the codeblock from being executed.
504This utility function takes a BLOCK or code reference and "unblocks" it, 515This utility function takes a BLOCK or code reference and "unblocks" it,
505returning the new coderef. This means that the new coderef will return 516returning the new coderef. This means that the new coderef will return
506immediately without blocking, returning nothing, while the original code 517immediately without blocking, returning nothing, while the original code
507ref will be called (with parameters) from within its own coroutine. 518ref will be called (with parameters) from within its own coroutine.
508 519
509The 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
510venerable L<Event|Event> module) are not coroutine-safe (a weaker form 521venerable L<Event|Event> module) are not coroutine-safe (a weaker form
511of thread-safety). This means you must not block within event callbacks, 522of thread-safety). This means you must not block within event callbacks,
512otherwise you might suffer from crashes or worse. 523otherwise you might suffer from crashes or worse.
513 524
514This function allows your callbacks to block by executing them in another 525This function allows your callbacks to block by executing them in another
525 536
526# we create a special coro because we want to cede, 537# we create a special coro because we want to cede,
527# to reduce pressure on the coro pool (because most callbacks 538# to reduce pressure on the coro pool (because most callbacks
528# return immediately and can be reused) and because we cannot cede 539# return immediately and can be reused) and because we cannot cede
529# inside an event callback. 540# inside an event callback.
530our $unblock_scheduler = async { 541our $unblock_scheduler = new Coro sub {
531 while () { 542 while () {
532 while (my $cb = pop @unblock_queue) { 543 while (my $cb = pop @unblock_queue) {
533 # this is an inlined copy of async_pool 544 # this is an inlined copy of async_pool
534 my $coro = (pop @pool or new Coro \&pool_handler); 545 my $coro = (pop @async_pool) || new Coro \&pool_handler;
535 546
536 $coro->{_invoke} = $cb; 547 $coro->{_invoke} = $cb;
537 $coro->ready; 548 $coro->ready;
538 cede; # for short-lived callbacks, this reduces pressure on the coro pool 549 cede; # for short-lived callbacks, this reduces pressure on the coro pool
539 } 550 }
540 schedule; # sleep well 551 schedule; # sleep well
541 } 552 }
542}; 553};
554$unblock_scheduler->desc ("[unblock_sub scheduler]");
543 555
544sub unblock_sub(&) { 556sub unblock_sub(&) {
545 my $cb = shift; 557 my $cb = shift;
546 558
547 sub { 559 sub {
560 572
561 - 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
562 destruction. very bad things might happen otherwise (usually segfaults). 574 destruction. very bad things might happen otherwise (usually segfaults).
563 575
564 - 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
565 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
566 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
567 this). 579 this).
568 580
569=head1 SEE ALSO 581=head1 SEE ALSO
570 582
583Lower level Configuration, Coroutine Environment: L<Coro::State>.
584
585Debugging: L<Coro::Debug>.
586
571Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>. 587Support/Utility: L<Coro::Specific>, L<Coro::Util>.
572 588
573Locking/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>.
574 590
575Event/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>.
576 592
593Compatibility: L<Coro::LWP>, L<Coro::Storable>, L<Coro::Select>.
594
577Embedding: L<Coro:MakeMaker> 595Embedding: L<Coro::MakeMaker>.
578 596
579=head1 AUTHOR 597=head1 AUTHOR
580 598
581 Marc Lehmann <schmorp@schmorp.de> 599 Marc Lehmann <schmorp@schmorp.de>
582 http://home.schmorp.de/ 600 http://home.schmorp.de/

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