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

Comparing Coro/Coro.pm (file contents):
Revision 1.32 by root, Sun Sep 2 01:03:53 2001 UTC vs.
Revision 1.128 by root, Wed Sep 19 21:39:15 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
26This module is still experimental, see the BUGS section below. 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).
27 34
28In this module, coroutines are defined as "callchain + lexical variables 35In this module, coroutines are defined as "callchain + lexical variables +
29+ @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own 36@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,
30callchain, it's own set of lexicals and it's own set of perl's most 37its own set of lexicals and its own set of perls most important global
31important global variables. 38variables.
32 39
33=cut 40=cut
34 41
35package Coro; 42package Coro;
36 43
44use strict;
45no warnings "uninitialized";
46
37use Coro::State; 47use Coro::State;
38 48
39use base Exporter; 49use base qw(Coro::State Exporter);
40 50
41$VERSION = 0.49; 51our $idle; # idle handler
52our $main; # main coroutine
53our $current; # current coroutine
42 54
55our $VERSION = '3.7';
56
43@EXPORT = qw(async cede schedule terminate current); 57our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
44%EXPORT_TAGS = ( 58our %EXPORT_TAGS = (
45 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], 59 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
46); 60);
47@EXPORT_OK = @{$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 (@_) {
75 }; 92 };
76 } 93 }
77 94
78} 95}
79 96
97=over 4
98
80=item $main 99=item $main
81 100
82This coroutine represents the main program. 101This coroutine represents the main program.
83 102
84=cut 103=cut
85 104
86our $main = new Coro; 105$main = new Coro;
87 106
88=item $current (or as function: current) 107=item $current (or as function: current)
89 108
90The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course). 109The current coroutine (the last coroutine switched to). The initial value
110is C<$main> (of course).
111
112This variable is B<strictly> I<read-only>. It is provided for performance
113reasons. If performance is not essential you are encouraged to use the
114C<Coro::current> function instead.
91 115
92=cut 116=cut
93 117
94# maybe some other module used Coro::Specific before... 118# maybe some other module used Coro::Specific before...
95if ($current) {
96 $main->{specific} = $current->{specific}; 119$main->{specific} = $current->{specific}
97} 120 if $current;
98 121
99our $current = $main; 122_set_current $main;
100 123
101sub current() { $current } 124sub current() { $current }
102 125
103=item $idle 126=item $idle
104 127
105The coroutine to switch to when no other coroutine is running. The default 128A callback that is called whenever the scheduler finds no ready coroutines
106implementation prints "FATAL: deadlock detected" and exits. 129to run. The default implementation prints "FATAL: deadlock detected" and
130exits, because the program has no other way to continue.
107 131
108=cut 132This 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
134coroutine so the scheduler can run it.
109 135
110# should be done using priorities :( 136Please note that if your callback recursively invokes perl (e.g. for event
111our $idle = new Coro sub { 137handlers), then it must be prepared to be called recursively.
112 print STDERR "FATAL: deadlock detected\n"; 138
113 exit(51); 139=cut
140
141$idle = sub {
142 require Carp;
143 Carp::croak ("FATAL: deadlock detected");
114}; 144};
145
146sub _cancel {
147 my ($self) = @_;
148
149 # free coroutine data and mark as destructed
150 $self->_destroy
151 or return;
152
153 # call all destruction callbacks
154 $_->(@{$self->{status}})
155 for @{(delete $self->{destroy_cb}) || []};
156}
115 157
116# this coroutine is necessary because a coroutine 158# this coroutine is necessary because a coroutine
117# cannot destroy itself. 159# cannot destroy itself.
118my @destroy; 160my @destroy;
161my $manager;
162
119my $manager = new Coro sub { 163$manager = new Coro sub {
120 while() { 164 while () {
121 delete ((pop @destroy)->{_coro_state}) while @destroy; 165 (shift @destroy)->_cancel
166 while @destroy;
167
122 &schedule; 168 &schedule;
123 } 169 }
124}; 170};
125 171
172$manager->prio (PRIO_MAX);
173
126# static methods. not really. 174# static methods. not really.
127 175
176=back
177
128=head2 STATIC METHODS 178=head2 STATIC METHODS
129 179
130Static methods are actually functions that operate on the current process only. 180Static methods are actually functions that operate on the current coroutine only.
131 181
132=over 4 182=over 4
133 183
134=item async { ... } [@args...] 184=item async { ... } [@args...]
135 185
136Create a new asynchronous process and return it's process object 186Create a new asynchronous coroutine and return it's coroutine object
137(usually unused). When the sub returns the new process is automatically 187(usually unused). When the sub returns the new coroutine is automatically
138terminated. 188terminated.
189
190Calling C<exit> in a coroutine will do the same as calling exit outside
191the coroutine. Likewise, when the coroutine dies, the program will exit,
192just as it would in the main program.
139 193
140 # create a new coroutine that just prints its arguments 194 # create a new coroutine that just prints its arguments
141 async { 195 async {
142 print "@_\n"; 196 print "@_\n";
143 } 1,2,3,4; 197 } 1,2,3,4;
144 198
145The coderef you submit MUST NOT be a closure that refers to variables
146in an outer scope. This does NOT work. Pass arguments into it instead.
147
148=cut 199=cut
149 200
150sub async(&@) { 201sub async(&@) {
151 my $pid = new Coro @_; 202 my $coro = new Coro @_;
152 $manager->ready; # this ensures that the stack is cloned from the manager
153 $pid->ready; 203 $coro->ready;
154 $pid; 204 $coro
205}
206
207=item async_pool { ... } [@args...]
208
209Similar to C<async>, but uses a coroutine pool, so you should not call
210terminate or join (although you are allowed to), and you get a coroutine
211that might have executed other code already (which can be good or bad :).
212
213Also, the block is executed in an C<eval> context and a warning will be
214issued in case of an exception instead of terminating the program, as
215C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
216will not work in the expected way, unless you call terminate or cancel,
217which somehow defeats the purpose of pooling.
218
219The priority will be reset to C<0> after each job, otherwise the coroutine
220will be re-used "as-is".
221
222The pool size is limited to 8 idle coroutines (this can be adjusted by
223changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
224required.
225
226If you are concerned about pooled coroutines growing a lot because a
227single C<async_pool> used a lot of stackspace you can e.g. C<async_pool {
228terminate }> once per second or so to slowly replenish the pool.
229
230=cut
231
232our $POOL_SIZE = 8;
233our @pool;
234
235sub pool_handler {
236 while () {
237 eval {
238 my ($cb, @arg) = @{ delete $current->{_invoke} or return };
239 $cb->(@arg);
240 };
241 warn $@ if $@;
242
243 last if @pool >= $POOL_SIZE;
244 push @pool, $current;
245
246 $current->save (Coro::State::SAVE_DEF);
247 $current->prio (0);
248 schedule;
249 }
250}
251
252sub async_pool(&@) {
253 # this is also inlined into the unlock_scheduler
254 my $coro = (pop @pool) || do {
255 my $coro = new Coro \&pool_handler;
256 $coro->{desc} = "async_pool";
257 $coro
258 };
259
260 $coro->{_invoke} = [@_];
261 $coro->ready;
262
263 $coro
155} 264}
156 265
157=item schedule 266=item schedule
158 267
159Calls the scheduler. Please note that the current process will not be put 268Calls the scheduler. Please note that the current coroutine will not be put
160into the ready queue, so calling this function usually means you will 269into the ready queue, so calling this function usually means you will
161never be called again. 270never be called again unless something else (e.g. an event handler) calls
271ready.
162 272
163=cut 273The canonical way to wait on external events is this:
274
275 {
276 # remember current coroutine
277 my $current = $Coro::current;
278
279 # register a hypothetical event handler
280 on_event_invoke sub {
281 # wake up sleeping coroutine
282 $current->ready;
283 undef $current;
284 };
285
286 # call schedule until event occurred.
287 # in case we are woken up for other reasons
288 # (current still defined), loop.
289 Coro::schedule while $current;
290 }
164 291
165=item cede 292=item cede
166 293
167"Cede" to other processes. This function puts the current process into the 294"Cede" to other coroutines. This function puts the current coroutine into the
168ready queue and calls C<schedule>, which has the effect of giving up the 295ready queue and calls C<schedule>, which has the effect of giving up the
169current "timeslice" to other coroutines of the same or higher priority. 296current "timeslice" to other coroutines of the same or higher priority.
170 297
171=cut 298Returns true if at least one coroutine switch has happened.
172 299
300=item Coro::cede_notself
301
302Works like cede, but is not exported by default and will cede to any
303coroutine, regardless of priority, once.
304
305Returns true if at least one coroutine switch has happened.
306
173=item terminate 307=item terminate [arg...]
174 308
175Terminates the current process. 309Terminates the current coroutine with the given status values (see L<cancel>).
176
177Future versions of this function will allow result arguments.
178 310
179=cut 311=cut
180 312
181sub terminate { 313sub terminate {
182 $current->cancel; 314 $current->cancel (@_);
183 &schedule;
184 die; # NORETURN
185} 315}
186 316
187=back 317=back
188 318
189# dynamic methods 319# dynamic methods
190 320
191=head2 PROCESS METHODS 321=head2 COROUTINE METHODS
192 322
193These are the methods you can call on process objects. 323These are the methods you can call on coroutine objects.
194 324
195=over 4 325=over 4
196 326
197=item new Coro \&sub [, @args...] 327=item new Coro \&sub [, @args...]
198 328
199Create a new process and return it. When the sub returns the process 329Create a new coroutine and return it. When the sub returns the coroutine
200automatically terminates. To start the process you must first put it into 330automatically terminates as if C<terminate> with the returned values were
331called. To make the coroutine run you must first put it into the ready queue
201the ready queue by calling the ready method. 332by calling the ready method.
202 333
203The coderef you submit MUST NOT be a closure that refers to variables 334See C<async> for additional discussion.
204in an outer scope. This does NOT work. Pass arguments into it instead.
205 335
206=cut 336=cut
207 337
208sub _newcoro { 338sub _run_coro {
209 terminate &{+shift}; 339 terminate &{+shift};
210} 340}
211 341
212sub new { 342sub new {
213 my $class = shift; 343 my $class = shift;
214 bless {
215 _coro_state => (new Coro::State $_[0] && \&_newcoro, @_),
216 }, $class;
217}
218 344
219=item $process->ready 345 $class->SUPER::new (\&_run_coro, @_)
346}
220 347
221Put the current process into the ready queue. 348=item $success = $coroutine->ready
222 349
223=cut 350Put the given coroutine into the ready queue (according to it's priority)
351and return true. If the coroutine is already in the ready queue, do nothing
352and return false.
224 353
225=item $process->cancel 354=item $is_ready = $coroutine->is_ready
226 355
227Like C<terminate>, but terminates the specified process instead. 356Return wether the coroutine is currently the ready queue or not,
357
358=item $coroutine->cancel (arg...)
359
360Terminates the given coroutine and makes it return the given arguments as
361status (default: the empty list). Never returns if the coroutine is the
362current coroutine.
228 363
229=cut 364=cut
230 365
231sub cancel { 366sub cancel {
367 my $self = shift;
368 $self->{status} = [@_];
369
370 if ($current == $self) {
232 push @destroy, $_[0]; 371 push @destroy, $self;
233 $manager->ready; 372 $manager->ready;
373 &schedule while 1;
374 } else {
375 $self->_cancel;
376 }
234} 377}
235 378
379=item $coroutine->join
380
381Wait until the coroutine terminates and return any values given to the
382C<terminate> or C<cancel> functions. C<join> can be called multiple times
383from multiple coroutine.
384
385=cut
386
387sub join {
388 my $self = shift;
389
390 unless ($self->{status}) {
391 my $current = $current;
392
393 push @{$self->{destroy_cb}}, sub {
394 $current->ready;
395 undef $current;
396 };
397
398 &schedule while $current;
399 }
400
401 wantarray ? @{$self->{status}} : $self->{status}[0];
402}
403
404=item $coroutine->on_destroy (\&cb)
405
406Registers a callback that is called when this coroutine gets destroyed,
407but before it is joined. The callback gets passed the terminate arguments,
408if any.
409
410=cut
411
412sub on_destroy {
413 my ($self, $cb) = @_;
414
415 push @{ $self->{destroy_cb} }, $cb;
416}
417
236=item $oldprio = $process->prio($newprio) 418=item $oldprio = $coroutine->prio ($newprio)
237 419
238Sets the priority of the process. Higher priority processes get run before 420Sets (or gets, if the argument is missing) the priority of the
239lower priority processes. Priorities are smalled signed integer (currently 421coroutine. Higher priority coroutines get run before lower priority
422coroutines. Priorities are small signed integers (currently -4 .. +3),
240-4 .. +3), that you can refer to using PRIO_xxx constants (use the import 423that you can refer to using PRIO_xxx constants (use the import tag :prio
241tag :prio to get then): 424to get then):
242 425
243 PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN 426 PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
244 3 > 1 > 0 > -1 > -3 > -4 427 3 > 1 > 0 > -1 > -3 > -4
245 428
246 # set priority to HIGH 429 # set priority to HIGH
247 current->prio(PRIO_HIGH); 430 current->prio(PRIO_HIGH);
248 431
249The idle coroutine ($Coro::idle) always has a lower priority than any 432The idle coroutine ($Coro::idle) always has a lower priority than any
250existing coroutine. 433existing coroutine.
251 434
252Changing the priority of the current process will take effect immediately, 435Changing the priority of the current coroutine will take effect immediately,
253but changing the priority of processes in the ready queue (but not 436but changing the priority of coroutines in the ready queue (but not
254running) will only take effect after the next schedule (of that 437running) will only take effect after the next schedule (of that
255process). This is a bug that will be fixed in some future version. 438coroutine). This is a bug that will be fixed in some future version.
256 439
257=cut
258
259sub prio {
260 my $old = $_[0]{prio};
261 $_[0]{prio} = $_[1] if @_ > 1;
262 $old;
263}
264
265=item $newprio = $process->nice($change) 440=item $newprio = $coroutine->nice ($change)
266 441
267Similar to C<prio>, but subtract the given value from the priority (i.e. 442Similar to C<prio>, but subtract the given value from the priority (i.e.
268higher values mean lower priority, just as in unix). 443higher values mean lower priority, just as in unix).
269 444
270=cut 445=item $olddesc = $coroutine->desc ($newdesc)
271 446
272sub nice { 447Sets (or gets in case the argument is missing) the description for this
273 $_[0]{prio} -= $_[1]; 448coroutine. This is just a free-form string you can associate with a coroutine.
449
450=cut
451
452sub desc {
453 my $old = $_[0]{desc};
454 $_[0]{desc} = $_[1] if @_ > 1;
455 $old;
274} 456}
275 457
276=back 458=back
277 459
460=head2 GLOBAL FUNCTIONS
461
462=over 4
463
464=item Coro::nready
465
466Returns the number of coroutines that are currently in the ready state,
467i.e. that can be switched to. The value C<0> means that the only runnable
468coroutine is the currently running one, so C<cede> would have no effect,
469and C<schedule> would cause a deadlock unless there is an idle handler
470that wakes up some coroutines.
471
472=item my $guard = Coro::guard { ... }
473
474This creates and returns a guard object. Nothing happens until the object
475gets destroyed, in which case the codeblock given as argument will be
476executed. This is useful to free locks or other resources in case of a
477runtime error or when the coroutine gets canceled, as in both cases the
478guard block will be executed. The guard object supports only one method,
479C<< ->cancel >>, which will keep the codeblock from being executed.
480
481Example: set some flag and clear it again when the coroutine gets canceled
482or the function returns:
483
484 sub do_something {
485 my $guard = Coro::guard { $busy = 0 };
486 $busy = 1;
487
488 # do something that requires $busy to be true
489 }
490
491=cut
492
493sub guard(&) {
494 bless \(my $cb = $_[0]), "Coro::guard"
495}
496
497sub Coro::guard::cancel {
498 ${$_[0]} = sub { };
499}
500
501sub Coro::guard::DESTROY {
502 ${$_[0]}->();
503}
504
505
506=item unblock_sub { ... }
507
508This utility function takes a BLOCK or code reference and "unblocks" it,
509returning the new coderef. This means that the new coderef will return
510immediately without blocking, returning nothing, while the original code
511ref will be called (with parameters) from within its own coroutine.
512
513The reason this function exists is that many event libraries (such as the
514venerable L<Event|Event> module) are not coroutine-safe (a weaker form
515of thread-safety). This means you must not block within event callbacks,
516otherwise you might suffer from crashes or worse.
517
518This function allows your callbacks to block by executing them in another
519coroutine where it is safe to block. One example where blocking is handy
520is when you use the L<Coro::AIO|Coro::AIO> functions to save results to
521disk.
522
523In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
524creating event callbacks that want to block.
525
526=cut
527
528our @unblock_queue;
529
530# we create a special coro because we want to cede,
531# to reduce pressure on the coro pool (because most callbacks
532# return immediately and can be reused) and because we cannot cede
533# inside an event callback.
534our $unblock_scheduler = async {
535 while () {
536 while (my $cb = pop @unblock_queue) {
537 # this is an inlined copy of async_pool
538 my $coro = (pop @pool or new Coro \&pool_handler);
539
540 $coro->{_invoke} = $cb;
541 $coro->ready;
542 cede; # for short-lived callbacks, this reduces pressure on the coro pool
543 }
544 schedule; # sleep well
545 }
546};
547
548sub unblock_sub(&) {
549 my $cb = shift;
550
551 sub {
552 unshift @unblock_queue, [$cb, @_];
553 $unblock_scheduler->ready;
554 }
555}
556
557=back
558
278=cut 559=cut
279 560
2801; 5611;
281 562
282=head1 BUGS/LIMITATIONS 563=head1 BUGS/LIMITATIONS
283 564
284 - could be faster, especially when the core would introduce special 565 - you must make very sure that no coro is still active on global
285 support for coroutines (like it does for threads). 566 destruction. very bad things might happen otherwise (usually segfaults).
286 - there is still a memleak on coroutine termination that I could not 567
287 identify. Could be as small as a single SV.
288 - this module is not well-tested.
289 - if variables or arguments "disappear" (become undef) or become
290 corrupted please contact the author so he cen iron out the
291 remaining bugs.
292 - this module is not thread-safe. You must only ever use this module from 568 - this module is not thread-safe. You should only ever use this module
293 the same thread (this requirement might be loosened in the future to 569 from the same thread (this requirement might be loosened in the future
294 allow per-thread schedulers, but Coro::State does not yet allow this). 570 to allow per-thread schedulers, but Coro::State does not yet allow
571 this).
295 572
296=head1 SEE ALSO 573=head1 SEE ALSO
297 574
298L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>, 575Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.
299L<Coro::Signal>, L<Coro::State>, L<Coro::Event>, L<Coro::RWLock>, 576
300L<Coro::Handle>, L<Coro::Socket>. 577Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
578
579Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.
580
581Embedding: L<Coro:MakeMaker>
301 582
302=head1 AUTHOR 583=head1 AUTHOR
303 584
304 Marc Lehmann <pcg@goof.com> 585 Marc Lehmann <schmorp@schmorp.de>
305 http://www.goof.com/pcg/marc/ 586 http://home.schmorp.de/
306 587
307=cut 588=cut
308 589

Diff Legend

Removed lines
+ Added lines
< Changed lines
> Changed lines