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

Comparing cvsroot/Coro/Coro.pm (file contents):
Revision 1.32 by root, Sun Sep 2 01:03:53 2001 UTC vs.
Revision 1.129 by root, Wed Sep 19 22:33:08 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 {
164 $current->desc ("[coro manager]");
165
120 while() { 166 while () {
121 delete ((pop @destroy)->{_coro_state}) while @destroy; 167 (shift @destroy)->_cancel
168 while @destroy;
169
122 &schedule; 170 &schedule;
123 } 171 }
124}; 172};
125 173
174$manager->prio (PRIO_MAX);
175
126# static methods. not really. 176# static methods. not really.
127 177
178=back
179
128=head2 STATIC METHODS 180=head2 STATIC METHODS
129 181
130Static methods are actually functions that operate on the current process only. 182Static methods are actually functions that operate on the current coroutine only.
131 183
132=over 4 184=over 4
133 185
134=item async { ... } [@args...] 186=item async { ... } [@args...]
135 187
136Create a new asynchronous process and return it's process object 188Create a new asynchronous coroutine and return it's coroutine object
137(usually unused). When the sub returns the new process is automatically 189(usually unused). When the sub returns the new coroutine is automatically
138terminated. 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.
139 195
140 # create a new coroutine that just prints its arguments 196 # create a new coroutine that just prints its arguments
141 async { 197 async {
142 print "@_\n"; 198 print "@_\n";
143 } 1,2,3,4; 199 } 1,2,3,4;
144 200
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 201=cut
149 202
150sub async(&@) { 203sub async(&@) {
151 my $pid = new Coro @_; 204 my $coro = new Coro @_;
152 $manager->ready; # this ensures that the stack is cloned from the manager
153 $pid->ready; 205 $coro->ready;
154 $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 {
230terminate }> once per second or so to slowly replenish the pool.
231
232=cut
233
234our $POOL_SIZE = 8;
235our @pool;
236
237sub pool_handler {
238 while () {
239 $current->{desc} = "[async_pool]";
240
241 eval {
242 my ($cb, @arg) = @{ delete $current->{_invoke} or return };
243 $cb->(@arg);
244 };
245 warn $@ if $@;
246
247 last if @pool >= $POOL_SIZE;
248
249 push @pool, $current;
250 $current->{desc} = "[async_pool idle]";
251 $current->save (Coro::State::SAVE_DEF);
252 $current->prio (0);
253 schedule;
254 }
255}
256
257sub async_pool(&@) {
258 # this is also inlined into the unlock_scheduler
259 my $coro = (pop @pool) || new Coro \&pool_handler;;
260
261 $coro->{_invoke} = [@_];
262 $coro->ready;
263
264 $coro
155} 265}
156 266
157=item schedule 267=item schedule
158 268
159Calls the scheduler. Please note that the current process will not be put 269Calls the scheduler. Please note that the current coroutine will not be put
160into the ready queue, so calling this function usually means you will 270into the ready queue, so calling this function usually means you will
161never be called again. 271never be called again unless something else (e.g. an event handler) calls
272ready.
162 273
163=cut 274The canonical way to wait on external events is this:
275
276 {
277 # remember current coroutine
278 my $current = $Coro::current;
279
280 # register a hypothetical event handler
281 on_event_invoke sub {
282 # wake up sleeping coroutine
283 $current->ready;
284 undef $current;
285 };
286
287 # call schedule until event occurred.
288 # in case we are woken up for other reasons
289 # (current still defined), loop.
290 Coro::schedule while $current;
291 }
164 292
165=item cede 293=item cede
166 294
167"Cede" to other processes. This function puts the current process into the 295"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 296ready queue and calls C<schedule>, which has the effect of giving up the
169current "timeslice" to other coroutines of the same or higher priority. 297current "timeslice" to other coroutines of the same or higher priority.
170 298
171=cut 299Returns true if at least one coroutine switch has happened.
172 300
301=item Coro::cede_notself
302
303Works like cede, but is not exported by default and will cede to any
304coroutine, regardless of priority, once.
305
306Returns true if at least one coroutine switch has happened.
307
173=item terminate 308=item terminate [arg...]
174 309
175Terminates the current process. 310Terminates the current coroutine with the given status values (see L<cancel>).
176
177Future versions of this function will allow result arguments.
178 311
179=cut 312=cut
180 313
181sub terminate { 314sub terminate {
182 $current->cancel; 315 $current->cancel (@_);
183 &schedule;
184 die; # NORETURN
185} 316}
186 317
187=back 318=back
188 319
189# dynamic methods 320# dynamic methods
190 321
191=head2 PROCESS METHODS 322=head2 COROUTINE METHODS
192 323
193These are the methods you can call on process objects. 324These are the methods you can call on coroutine objects.
194 325
195=over 4 326=over 4
196 327
197=item new Coro \&sub [, @args...] 328=item new Coro \&sub [, @args...]
198 329
199Create a new process and return it. When the sub returns the process 330Create a new coroutine and return it. When the sub returns the coroutine
200automatically terminates. To start the process you must first put it into 331automatically terminates as if C<terminate> with the returned values were
332called. To make the coroutine run you must first put it into the ready queue
201the ready queue by calling the ready method. 333by calling the ready method.
202 334
203The coderef you submit MUST NOT be a closure that refers to variables 335See C<async> for additional discussion.
204in an outer scope. This does NOT work. Pass arguments into it instead.
205 336
206=cut 337=cut
207 338
208sub _newcoro { 339sub _run_coro {
209 terminate &{+shift}; 340 terminate &{+shift};
210} 341}
211 342
212sub new { 343sub new {
213 my $class = shift; 344 my $class = shift;
214 bless {
215 _coro_state => (new Coro::State $_[0] && \&_newcoro, @_),
216 }, $class;
217}
218 345
219=item $process->ready 346 $class->SUPER::new (\&_run_coro, @_)
347}
220 348
221Put the current process into the ready queue. 349=item $success = $coroutine->ready
222 350
223=cut 351Put the given coroutine into the ready queue (according to it's priority)
352and return true. If the coroutine is already in the ready queue, do nothing
353and return false.
224 354
225=item $process->cancel 355=item $is_ready = $coroutine->is_ready
226 356
227Like C<terminate>, but terminates the specified process instead. 357Return wether the coroutine is currently the ready queue or not,
358
359=item $coroutine->cancel (arg...)
360
361Terminates the given coroutine and makes it return the given arguments as
362status (default: the empty list). Never returns if the coroutine is the
363current coroutine.
228 364
229=cut 365=cut
230 366
231sub cancel { 367sub cancel {
368 my $self = shift;
369 $self->{status} = [@_];
370
371 if ($current == $self) {
232 push @destroy, $_[0]; 372 push @destroy, $self;
233 $manager->ready; 373 $manager->ready;
374 &schedule while 1;
375 } else {
376 $self->_cancel;
377 }
234} 378}
235 379
380=item $coroutine->join
381
382Wait until the coroutine terminates and return any values given to the
383C<terminate> or C<cancel> functions. C<join> can be called multiple times
384from multiple coroutine.
385
386=cut
387
388sub join {
389 my $self = shift;
390
391 unless ($self->{status}) {
392 my $current = $current;
393
394 push @{$self->{destroy_cb}}, sub {
395 $current->ready;
396 undef $current;
397 };
398
399 &schedule while $current;
400 }
401
402 wantarray ? @{$self->{status}} : $self->{status}[0];
403}
404
405=item $coroutine->on_destroy (\&cb)
406
407Registers a callback that is called when this coroutine gets destroyed,
408but before it is joined. The callback gets passed the terminate arguments,
409if any.
410
411=cut
412
413sub on_destroy {
414 my ($self, $cb) = @_;
415
416 push @{ $self->{destroy_cb} }, $cb;
417}
418
236=item $oldprio = $process->prio($newprio) 419=item $oldprio = $coroutine->prio ($newprio)
237 420
238Sets the priority of the process. Higher priority processes get run before 421Sets (or gets, if the argument is missing) the priority of the
239lower priority processes. Priorities are smalled signed integer (currently 422coroutine. Higher priority coroutines get run before lower priority
423coroutines. Priorities are small signed integers (currently -4 .. +3),
240-4 .. +3), that you can refer to using PRIO_xxx constants (use the import 424that you can refer to using PRIO_xxx constants (use the import tag :prio
241tag :prio to get then): 425to get then):
242 426
243 PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN 427 PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
244 3 > 1 > 0 > -1 > -3 > -4 428 3 > 1 > 0 > -1 > -3 > -4
245 429
246 # set priority to HIGH 430 # set priority to HIGH
247 current->prio(PRIO_HIGH); 431 current->prio(PRIO_HIGH);
248 432
249The idle coroutine ($Coro::idle) always has a lower priority than any 433The idle coroutine ($Coro::idle) always has a lower priority than any
250existing coroutine. 434existing coroutine.
251 435
252Changing the priority of the current process will take effect immediately, 436Changing the priority of the current coroutine will take effect immediately,
253but changing the priority of processes in the ready queue (but not 437but changing the priority of coroutines in the ready queue (but not
254running) will only take effect after the next schedule (of that 438running) will only take effect after the next schedule (of that
255process). This is a bug that will be fixed in some future version. 439coroutine). This is a bug that will be fixed in some future version.
256 440
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) 441=item $newprio = $coroutine->nice ($change)
266 442
267Similar to C<prio>, but subtract the given value from the priority (i.e. 443Similar to C<prio>, but subtract the given value from the priority (i.e.
268higher values mean lower priority, just as in unix). 444higher values mean lower priority, just as in unix).
269 445
270=cut 446=item $olddesc = $coroutine->desc ($newdesc)
271 447
272sub nice { 448Sets (or gets in case the argument is missing) the description for this
273 $_[0]{prio} -= $_[1]; 449coroutine. This is just a free-form string you can associate with a coroutine.
450
451=cut
452
453sub desc {
454 my $old = $_[0]{desc};
455 $_[0]{desc} = $_[1] if @_ > 1;
456 $old;
274} 457}
275 458
276=back 459=back
277 460
461=head2 GLOBAL FUNCTIONS
462
463=over 4
464
465=item Coro::nready
466
467Returns the number of coroutines that are currently in the ready state,
468i.e. that can be switched to. The value C<0> means that the only runnable
469coroutine is the currently running one, so C<cede> would have no effect,
470and C<schedule> would cause a deadlock unless there is an idle handler
471that wakes up some coroutines.
472
473=item my $guard = Coro::guard { ... }
474
475This creates and returns a guard object. Nothing happens until the object
476gets destroyed, in which case the codeblock given as argument will be
477executed. This is useful to free locks or other resources in case of a
478runtime error or when the coroutine gets canceled, as in both cases the
479guard block will be executed. The guard object supports only one method,
480C<< ->cancel >>, which will keep the codeblock from being executed.
481
482Example: set some flag and clear it again when the coroutine gets canceled
483or the function returns:
484
485 sub do_something {
486 my $guard = Coro::guard { $busy = 0 };
487 $busy = 1;
488
489 # do something that requires $busy to be true
490 }
491
492=cut
493
494sub guard(&) {
495 bless \(my $cb = $_[0]), "Coro::guard"
496}
497
498sub Coro::guard::cancel {
499 ${$_[0]} = sub { };
500}
501
502sub Coro::guard::DESTROY {
503 ${$_[0]}->();
504}
505
506
507=item unblock_sub { ... }
508
509This utility function takes a BLOCK or code reference and "unblocks" it,
510returning the new coderef. This means that the new coderef will return
511immediately without blocking, returning nothing, while the original code
512ref will be called (with parameters) from within its own coroutine.
513
514The reason this function exists is that many event libraries (such as the
515venerable L<Event|Event> module) are not coroutine-safe (a weaker form
516of thread-safety). This means you must not block within event callbacks,
517otherwise you might suffer from crashes or worse.
518
519This function allows your callbacks to block by executing them in another
520coroutine where it is safe to block. One example where blocking is handy
521is when you use the L<Coro::AIO|Coro::AIO> functions to save results to
522disk.
523
524In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
525creating event callbacks that want to block.
526
527=cut
528
529our @unblock_queue;
530
531# we create a special coro because we want to cede,
532# to reduce pressure on the coro pool (because most callbacks
533# return immediately and can be reused) and because we cannot cede
534# inside an event callback.
535our $unblock_scheduler = async {
536 $current->desc ("[unblock_sub scheduler]");
537 while () {
538 while (my $cb = pop @unblock_queue) {
539 # this is an inlined copy of async_pool
540 my $coro = (pop @pool or new Coro \&pool_handler);
541
542 $coro->{_invoke} = $cb;
543 $coro->ready;
544 cede; # for short-lived callbacks, this reduces pressure on the coro pool
545 }
546 schedule; # sleep well
547 }
548};
549
550sub unblock_sub(&) {
551 my $cb = shift;
552
553 sub {
554 unshift @unblock_queue, [$cb, @_];
555 $unblock_scheduler->ready;
556 }
557}
558
559=back
560
278=cut 561=cut
279 562
2801; 5631;
281 564
282=head1 BUGS/LIMITATIONS 565=head1 BUGS/LIMITATIONS
283 566
284 - could be faster, especially when the core would introduce special 567 - you must make very sure that no coro is still active on global
285 support for coroutines (like it does for threads). 568 destruction. very bad things might happen otherwise (usually segfaults).
286 - there is still a memleak on coroutine termination that I could not 569
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 570 - 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 571 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). 572 to allow per-thread schedulers, but Coro::State does not yet allow
573 this).
295 574
296=head1 SEE ALSO 575=head1 SEE ALSO
297 576
298L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>, 577Support/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>, 578
300L<Coro::Handle>, L<Coro::Socket>. 579Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
580
581Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.
582
583Embedding: L<Coro:MakeMaker>
301 584
302=head1 AUTHOR 585=head1 AUTHOR
303 586
304 Marc Lehmann <pcg@goof.com> 587 Marc Lehmann <schmorp@schmorp.de>
305 http://www.goof.com/pcg/marc/ 588 http://home.schmorp.de/
306 589
307=cut 590=cut
308 591

Diff Legend

Removed lines
+ Added lines
< Changed lines
> Changed lines