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

Comparing Coro/Coro.pm (file contents):
Revision 1.52 by root, Tue May 27 00:26:34 2003 UTC vs.
Revision 1.142 by root, Tue Oct 2 23:16:24 2007 UTC

8 8
9 async { 9 async {
10 # some asynchronous thread of execution 10 # some asynchronous thread of execution
11 }; 11 };
12 12
13 # alternatively create an async process like this: 13 # alternatively create an async coroutine like this:
14 14
15 sub some_func : Coro { 15 sub some_func : Coro {
16 # some more async code 16 # some more async code
17 } 17 }
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@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,
28callchain, it's own set of lexicals and it's own set of perl's most 37its own set of lexicals and its own set of perls most important global
29important global variables. 38variables.
30 39
31=cut 40=cut
32 41
33package Coro; 42package Coro;
34 43
44use strict;
35no warnings qw(uninitialized); 45no warnings "uninitialized";
36 46
37use Coro::State; 47use Coro::State;
38 48
39use base Exporter; 49use base qw(Coro::State Exporter);
40 50
41$VERSION = 0.652; 51our $idle; # idle handler
52our $main; # main coroutine
53our $current; # current coroutine
42 54
55our $VERSION = '3.8';
56
43@EXPORT = qw(async cede schedule terminate current); 57our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
44%EXPORT_TAGS = ( 58our %EXPORT_TAGS = (
45 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], 59 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
46); 60);
47@EXPORT_OK = @{$EXPORT_TAGS{prio}}; 61our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
48 62
49{ 63{
50 my @async; 64 my @async;
51 my $init; 65 my $init;
52 66
53 # this way of handling attributes simply is NOT scalable ;() 67 # this way of handling attributes simply is NOT scalable ;()
54 sub import { 68 sub import {
69 no strict 'refs';
70
55 Coro->export_to_level(1, @_); 71 Coro->export_to_level (1, @_);
72
56 my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE}; 73 my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
57 *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub { 74 *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
58 my ($package, $ref) = (shift, shift); 75 my ($package, $ref) = (shift, shift);
59 my @attrs; 76 my @attrs;
60 for (@_) { 77 for (@_) {
83 100
84This coroutine represents the main program. 101This coroutine represents the main program.
85 102
86=cut 103=cut
87 104
88our $main = new Coro; 105$main = new Coro;
89 106
90=item $current (or as function: current) 107=item $current (or as function: current)
91 108
92The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course). 109The current coroutine (the last coroutine switched to). The initial value
110is C<$main> (of course).
93 111
112This variable is B<strictly> I<read-only>. It is provided for performance
113reasons. If performance is not essential you are encouraged to use the
114C<Coro::current> function instead.
115
94=cut 116=cut
117
118$main->{desc} = "[main::]";
95 119
96# maybe some other module used Coro::Specific before... 120# maybe some other module used Coro::Specific before...
97if ($current) {
98 $main->{specific} = $current->{specific}; 121$main->{_specific} = $current->{_specific}
99} 122 if $current;
100 123
101our $current = $main; 124_set_current $main;
102 125
103sub current() { $current } 126sub current() { $current }
104 127
105=item $idle 128=item $idle
106 129
107The coroutine to switch to when no other coroutine is running. The default 130A callback that is called whenever the scheduler finds no ready coroutines
108implementation prints "FATAL: deadlock detected" and exits. 131to run. The default implementation prints "FATAL: deadlock detected" and
132exits, because the program has no other way to continue.
109 133
110=cut 134This hook is overwritten by modules such as C<Coro::Timer> and
135C<Coro::Event> to wait on an external event that hopefully wake up a
136coroutine so the scheduler can run it.
111 137
112# should be done using priorities :( 138Please note that if your callback recursively invokes perl (e.g. for event
113our $idle = new Coro sub { 139handlers), then it must be prepared to be called recursively.
114 print STDERR "FATAL: deadlock detected\n"; 140
115 exit(51); 141=cut
142
143$idle = sub {
144 require Carp;
145 Carp::croak ("FATAL: deadlock detected");
116}; 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}
117 159
118# this coroutine is necessary because a coroutine 160# this coroutine is necessary because a coroutine
119# cannot destroy itself. 161# cannot destroy itself.
120my @destroy; 162my @destroy;
121my $manager; 163my $manager;
164
122$manager = new Coro sub { 165$manager = new Coro sub {
123 while() { 166 while () {
124 # by overwriting the state object with the manager we destroy it 167 (shift @destroy)->_cancel
125 # while still being able to schedule this coroutine (in case it has
126 # been readied multiple times. this is harmless since the manager
127 # can be called as many times as neccessary and will always
128 # remove itself from the runqueue
129 while (@destroy) { 168 while @destroy;
130 my $coro = pop @destroy; 169
131 $coro->{status} ||= [];
132 $_->ready for @{delete $coro->{join} || []};
133 $coro->{_coro_state} = $manager->{_coro_state};
134 }
135 &schedule; 170 &schedule;
136 } 171 }
137}; 172};
173$manager->desc ("[coro manager]");
174$manager->prio (PRIO_MAX);
138 175
139# static methods. not really. 176# static methods. not really.
140 177
141=back 178=back
142 179
143=head2 STATIC METHODS 180=head2 STATIC METHODS
144 181
145Static methods are actually functions that operate on the current process only. 182Static methods are actually functions that operate on the current coroutine only.
146 183
147=over 4 184=over 4
148 185
149=item async { ... } [@args...] 186=item async { ... } [@args...]
150 187
151Create a new asynchronous process and return it's process object 188Create a new asynchronous coroutine and return it's coroutine object
152(usually unused). When the sub returns the new process is automatically 189(usually unused). When the sub returns the new coroutine is automatically
153terminated. 190terminated.
191
192Calling C<exit> in a coroutine will do the same as calling exit outside
193the coroutine. Likewise, when the coroutine dies, the program will exit,
194just as it would in the main program.
154 195
155 # create a new coroutine that just prints its arguments 196 # create a new coroutine that just prints its arguments
156 async { 197 async {
157 print "@_\n"; 198 print "@_\n";
158 } 1,2,3,4; 199 } 1,2,3,4;
159 200
160The coderef you submit MUST NOT be a closure that refers to variables
161in an outer scope. This does NOT work. Pass arguments into it instead.
162
163=cut 201=cut
164 202
165sub async(&@) { 203sub async(&@) {
166 my $pid = new Coro @_; 204 my $coro = new Coro @_;
167 $manager->ready; # this ensures that the stack is cloned from the manager
168 $pid->ready; 205 $coro->ready;
169 $pid; 206 $coro
207}
208
209=item async_pool { ... } [@args...]
210
211Similar to C<async>, but uses a coroutine pool, so you should not call
212terminate or join (although you are allowed to), and you get a coroutine
213that might have executed other code already (which can be good or bad :).
214
215Also, the block is executed in an C<eval> context and a warning will be
216issued in case of an exception instead of terminating the program, as
217C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
218will not work in the expected way, unless you call terminate or cancel,
219which somehow defeats the purpose of pooling.
220
221The priority will be reset to C<0> after each job, otherwise the coroutine
222will be re-used "as-is".
223
224The pool size is limited to 8 idle coroutines (this can be adjusted by
225changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
226required.
227
228If you are concerned about pooled coroutines growing a lot because a
229single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
230{ terminate }> once per second or so to slowly replenish the pool. In
231addition to that, when the stacks used by a handler grows larger than 16kb
232(adjustable with $Coro::POOL_RSS) it will also exit.
233
234=cut
235
236our $POOL_SIZE = 8;
237our $POOL_RSS = 16 * 1024;
238our @async_pool;
239
240sub pool_handler {
241 my $cb;
242
243 while () {
244 eval {
245 while () {
246 _pool_1 $cb;
247 &$cb;
248 _pool_2 $cb;
249 &schedule;
250 }
251 };
252
253 last if $@ eq "\3terminate\2\n";
254 warn $@ if $@;
255 }
256}
257
258sub async_pool(&@) {
259 # this is also inlined into the unlock_scheduler
260 my $coro = (pop @async_pool) || new Coro \&pool_handler;
261
262 $coro->{_invoke} = [@_];
263 $coro->ready;
264
265 $coro
170} 266}
171 267
172=item schedule 268=item schedule
173 269
174Calls the scheduler. Please note that the current process will not be put 270Calls the scheduler. Please note that the current coroutine will not be put
175into the ready queue, so calling this function usually means you will 271into the ready queue, so calling this function usually means you will
176never be called again. 272never be called again unless something else (e.g. an event handler) calls
273ready.
177 274
178=cut 275The canonical way to wait on external events is this:
276
277 {
278 # remember current coroutine
279 my $current = $Coro::current;
280
281 # register a hypothetical event handler
282 on_event_invoke sub {
283 # wake up sleeping coroutine
284 $current->ready;
285 undef $current;
286 };
287
288 # call schedule until event occurred.
289 # in case we are woken up for other reasons
290 # (current still defined), loop.
291 Coro::schedule while $current;
292 }
179 293
180=item cede 294=item cede
181 295
182"Cede" to other processes. This function puts the current process into the 296"Cede" to other coroutines. This function puts the current coroutine into the
183ready queue and calls C<schedule>, which has the effect of giving up the 297ready queue and calls C<schedule>, which has the effect of giving up the
184current "timeslice" to other coroutines of the same or higher priority. 298current "timeslice" to other coroutines of the same or higher priority.
185 299
186=cut 300Returns true if at least one coroutine switch has happened.
301
302=item Coro::cede_notself
303
304Works like cede, but is not exported by default and will cede to any
305coroutine, regardless of priority, once.
306
307Returns true if at least one coroutine switch has happened.
187 308
188=item terminate [arg...] 309=item terminate [arg...]
189 310
190Terminates the current process. 311Terminates the current coroutine with the given status values (see L<cancel>).
191 312
192Future versions of this function will allow result arguments. 313=item killall
314
315Kills/terminates/cancels all coroutines except the currently running
316one. This is useful after a fork, either in the child or the parent, as
317usually only one of them should inherit the running coroutines.
193 318
194=cut 319=cut
195 320
196sub terminate { 321sub terminate {
197 $current->{status} = [@_];
198 $current->cancel; 322 $current->cancel (@_);
199 &schedule; 323}
200 die; # NORETURN 324
325sub killall {
326 for (Coro::State::list) {
327 $_->cancel
328 if $_ != $current && UNIVERSAL::isa $_, "Coro";
329 }
201} 330}
202 331
203=back 332=back
204 333
205# dynamic methods 334# dynamic methods
206 335
207=head2 PROCESS METHODS 336=head2 COROUTINE METHODS
208 337
209These are the methods you can call on process objects. 338These are the methods you can call on coroutine objects.
210 339
211=over 4 340=over 4
212 341
213=item new Coro \&sub [, @args...] 342=item new Coro \&sub [, @args...]
214 343
215Create a new process and return it. When the sub returns the process 344Create a new coroutine and return it. When the sub returns the coroutine
216automatically terminates as if C<terminate> with the returned values were 345automatically terminates as if C<terminate> with the returned values were
217called. To make the process run you must first put it into the ready queue 346called. To make the coroutine run you must first put it into the ready queue
218by calling the ready method. 347by calling the ready method.
219 348
220=cut 349See C<async> for additional discussion.
221 350
351=cut
352
222sub _newcoro { 353sub _run_coro {
223 terminate &{+shift}; 354 terminate &{+shift};
224} 355}
225 356
226sub new { 357sub new {
227 my $class = shift; 358 my $class = shift;
228 bless {
229 _coro_state => (new Coro::State $_[0] && \&_newcoro, @_),
230 }, $class;
231}
232 359
233=item $process->ready 360 $class->SUPER::new (\&_run_coro, @_)
361}
234 362
235Put the given process into the ready queue. 363=item $success = $coroutine->ready
236 364
237=cut 365Put the given coroutine into the ready queue (according to it's priority)
366and return true. If the coroutine is already in the ready queue, do nothing
367and return false.
238 368
239=item $process->cancel 369=item $is_ready = $coroutine->is_ready
240 370
241Like C<terminate>, but terminates the specified process instead. 371Return wether the coroutine is currently the ready queue or not,
372
373=item $coroutine->cancel (arg...)
374
375Terminates the given coroutine and makes it return the given arguments as
376status (default: the empty list). Never returns if the coroutine is the
377current coroutine.
242 378
243=cut 379=cut
244 380
245sub cancel { 381sub cancel {
382 my $self = shift;
383 $self->{_status} = [@_];
384
385 if ($current == $self) {
246 push @destroy, $_[0]; 386 push @destroy, $self;
247 $manager->ready; 387 $manager->ready;
248 &schedule if $current == $_[0]; 388 &schedule while 1;
389 } else {
390 $self->_cancel;
391 }
249} 392}
250 393
251=item $process->join 394=item $coroutine->join
252 395
253Wait until the coroutine terminates and return any values given to the 396Wait until the coroutine terminates and return any values given to the
254C<terminate> function. C<join> can be called multiple times from multiple 397C<terminate> or C<cancel> functions. C<join> can be called multiple times
255processes. 398from multiple coroutine.
256 399
257=cut 400=cut
258 401
259sub join { 402sub join {
260 my $self = shift; 403 my $self = shift;
404
261 unless ($self->{status}) { 405 unless ($self->{_status}) {
262 push @{$self->{join}}, $current; 406 my $current = $current;
263 &schedule; 407
408 push @{$self->{_on_destroy}}, sub {
409 $current->ready;
410 undef $current;
411 };
412
413 &schedule while $current;
264 } 414 }
415
265 wantarray ? @{$self->{status}} : $self->{status}[0]; 416 wantarray ? @{$self->{_status}} : $self->{_status}[0];
266} 417}
267 418
419=item $coroutine->on_destroy (\&cb)
420
421Registers a callback that is called when this coroutine gets destroyed,
422but before it is joined. The callback gets passed the terminate arguments,
423if any.
424
425=cut
426
427sub on_destroy {
428 my ($self, $cb) = @_;
429
430 push @{ $self->{_on_destroy} }, $cb;
431}
432
268=item $oldprio = $process->prio($newprio) 433=item $oldprio = $coroutine->prio ($newprio)
269 434
270Sets (or gets, if the argument is missing) the priority of the 435Sets (or gets, if the argument is missing) the priority of the
271process. Higher priority processes get run before lower priority 436coroutine. Higher priority coroutines get run before lower priority
272processes. Priorities are small signed integers (currently -4 .. +3), 437coroutines. Priorities are small signed integers (currently -4 .. +3),
273that you can refer to using PRIO_xxx constants (use the import tag :prio 438that you can refer to using PRIO_xxx constants (use the import tag :prio
274to get then): 439to get then):
275 440
276 PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN 441 PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
277 3 > 1 > 0 > -1 > -3 > -4 442 3 > 1 > 0 > -1 > -3 > -4
280 current->prio(PRIO_HIGH); 445 current->prio(PRIO_HIGH);
281 446
282The idle coroutine ($Coro::idle) always has a lower priority than any 447The idle coroutine ($Coro::idle) always has a lower priority than any
283existing coroutine. 448existing coroutine.
284 449
285Changing the priority of the current process will take effect immediately, 450Changing the priority of the current coroutine will take effect immediately,
286but changing the priority of processes in the ready queue (but not 451but changing the priority of coroutines in the ready queue (but not
287running) will only take effect after the next schedule (of that 452running) will only take effect after the next schedule (of that
288process). This is a bug that will be fixed in some future version. 453coroutine). This is a bug that will be fixed in some future version.
289 454
290=cut
291
292sub prio {
293 my $old = $_[0]{prio};
294 $_[0]{prio} = $_[1] if @_ > 1;
295 $old;
296}
297
298=item $newprio = $process->nice($change) 455=item $newprio = $coroutine->nice ($change)
299 456
300Similar to C<prio>, but subtract the given value from the priority (i.e. 457Similar to C<prio>, but subtract the given value from the priority (i.e.
301higher values mean lower priority, just as in unix). 458higher values mean lower priority, just as in unix).
302 459
303=cut
304
305sub nice {
306 $_[0]{prio} -= $_[1];
307}
308
309=item $olddesc = $process->desc($newdesc) 460=item $olddesc = $coroutine->desc ($newdesc)
310 461
311Sets (or gets in case the argument is missing) the description for this 462Sets (or gets in case the argument is missing) the description for this
312process. This is just a free-form string you can associate with a process. 463coroutine. This is just a free-form string you can associate with a coroutine.
464
465This method simply sets the C<< $coroutine->{desc} >> member to the given string. You
466can modify this member directly if you wish.
313 467
314=cut 468=cut
315 469
316sub desc { 470sub desc {
317 my $old = $_[0]{desc}; 471 my $old = $_[0]{desc};
319 $old; 473 $old;
320} 474}
321 475
322=back 476=back
323 477
478=head2 GLOBAL FUNCTIONS
479
480=over 4
481
482=item Coro::nready
483
484Returns the number of coroutines that are currently in the ready state,
485i.e. that can be switched to. The value C<0> means that the only runnable
486coroutine is the currently running one, so C<cede> would have no effect,
487and C<schedule> would cause a deadlock unless there is an idle handler
488that wakes up some coroutines.
489
490=item my $guard = Coro::guard { ... }
491
492This creates and returns a guard object. Nothing happens until the object
493gets destroyed, in which case the codeblock given as argument will be
494executed. This is useful to free locks or other resources in case of a
495runtime error or when the coroutine gets canceled, as in both cases the
496guard block will be executed. The guard object supports only one method,
497C<< ->cancel >>, which will keep the codeblock from being executed.
498
499Example: set some flag and clear it again when the coroutine gets canceled
500or the function returns:
501
502 sub do_something {
503 my $guard = Coro::guard { $busy = 0 };
504 $busy = 1;
505
506 # do something that requires $busy to be true
507 }
508
509=cut
510
511sub guard(&) {
512 bless \(my $cb = $_[0]), "Coro::guard"
513}
514
515sub Coro::guard::cancel {
516 ${$_[0]} = sub { };
517}
518
519sub Coro::guard::DESTROY {
520 ${$_[0]}->();
521}
522
523
524=item unblock_sub { ... }
525
526This utility function takes a BLOCK or code reference and "unblocks" it,
527returning the new coderef. This means that the new coderef will return
528immediately without blocking, returning nothing, while the original code
529ref will be called (with parameters) from within its own coroutine.
530
531The reason this function exists is that many event libraries (such as the
532venerable L<Event|Event> module) are not coroutine-safe (a weaker form
533of thread-safety). This means you must not block within event callbacks,
534otherwise you might suffer from crashes or worse.
535
536This function allows your callbacks to block by executing them in another
537coroutine where it is safe to block. One example where blocking is handy
538is when you use the L<Coro::AIO|Coro::AIO> functions to save results to
539disk.
540
541In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
542creating event callbacks that want to block.
543
544=cut
545
546our @unblock_queue;
547
548# we create a special coro because we want to cede,
549# to reduce pressure on the coro pool (because most callbacks
550# return immediately and can be reused) and because we cannot cede
551# inside an event callback.
552our $unblock_scheduler = new Coro sub {
553 while () {
554 while (my $cb = pop @unblock_queue) {
555 # this is an inlined copy of async_pool
556 my $coro = (pop @async_pool) || new Coro \&pool_handler;
557
558 $coro->{_invoke} = $cb;
559 $coro->ready;
560 cede; # for short-lived callbacks, this reduces pressure on the coro pool
561 }
562 schedule; # sleep well
563 }
564};
565$unblock_scheduler->desc ("[unblock_sub scheduler]");
566
567sub unblock_sub(&) {
568 my $cb = shift;
569
570 sub {
571 unshift @unblock_queue, [$cb, @_];
572 $unblock_scheduler->ready;
573 }
574}
575
576=back
577
324=cut 578=cut
325 579
3261; 5801;
327 581
328=head1 BUGS/LIMITATIONS 582=head1 BUGS/LIMITATIONS
329 583
330 - you must make very sure that no coro is still active on global 584 - you must make very sure that no coro is still active on global
331 destruction. very bad things might happen otherwise (usually segfaults 585 destruction. very bad things might happen otherwise (usually segfaults).
332 or "panic: top_env").
333 586
334 - this module is not thread-safe. You should only ever use this module 587 - this module is not thread-safe. You should only ever use this module
335 from the same thread (this requirement might be losened in the future 588 from the same thread (this requirement might be loosened in the future
336 to allow per-thread schedulers, but Coro::State does not yet allow 589 to allow per-thread schedulers, but Coro::State does not yet allow
337 this). 590 this).
338 591
339=head1 SEE ALSO 592=head1 SEE ALSO
340 593
341L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>, 594Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.
342L<Coro::Signal>, L<Coro::State>, L<Coro::Event>, L<Coro::RWLock>, 595
343L<Coro::Handle>, L<Coro::Socket>. 596Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
597
598Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.
599
600Embedding: L<Coro:MakeMaker>
344 601
345=head1 AUTHOR 602=head1 AUTHOR
346 603
347 Marc Lehmann <pcg@goof.com> 604 Marc Lehmann <schmorp@schmorp.de>
348 http://www.goof.com/pcg/marc/ 605 http://home.schmorp.de/
349 606
350=cut 607=cut
351 608

Diff Legend

Removed lines
+ Added lines
< Changed lines
> Changed lines