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Revision 1.105 by root, Fri Jan 5 16:55:01 2007 UTC vs.
Revision 1.140 by root, Thu Sep 27 16:25:10 2007 UTC

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20 20
21=head1 DESCRIPTION 21=head1 DESCRIPTION
22 22
23This module collection manages coroutines. Coroutines are similar 23This module collection manages coroutines. Coroutines are similar
24to threads but don't run in parallel at the same time even on SMP 24to 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 25machines. The specific flavor of coroutine used in this module also
26guarentees you that it will not switch between coroutines unless 26guarantees you that it will not switch between coroutines unless
27necessary, at easily-identified points in your program, so locking and 27necessary, at easily-identified points in your program, so locking and
28parallel access are rarely an issue, making coroutine programming much 28parallel access are rarely an issue, making coroutine programming much
29safer than threads programming. 29safer than threads programming.
30 30
31(Perl, however, does not natively support real threads but instead does a 31(Perl, however, does not natively support real threads but instead does a
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50 50
51our $idle; # idle handler 51our $idle; # idle handler
52our $main; # main coroutine 52our $main; # main coroutine
53our $current; # current coroutine 53our $current; # current coroutine
54 54
55our $VERSION = '3.3'; 55our $VERSION = '3.8';
56 56
57our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); 57our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
58our %EXPORT_TAGS = ( 58our %EXPORT_TAGS = (
59 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], 59 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
60); 60);
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108 108
109The current coroutine (the last coroutine switched to). The initial value 109The current coroutine (the last coroutine switched to). The initial value
110is C<$main> (of course). 110is C<$main> (of course).
111 111
112This variable is B<strictly> I<read-only>. It is provided for performance 112This variable is B<strictly> I<read-only>. It is provided for performance
113reasons. If performance is not essentiel you are encouraged to use the 113reasons. If performance is not essential you are encouraged to use the
114C<Coro::current> function instead. 114C<Coro::current> function instead.
115 115
116=cut 116=cut
117
118$main->{desc} = "[main::]";
117 119
118# maybe some other module used Coro::Specific before... 120# maybe some other module used Coro::Specific before...
119$main->{specific} = $current->{specific} 121$main->{specific} = $current->{specific}
120 if $current; 122 if $current;
121 123
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166 while @destroy; 168 while @destroy;
167 169
168 &schedule; 170 &schedule;
169 } 171 }
170}; 172};
171 173$manager->desc ("[coro manager]");
172$manager->prio (PRIO_MAX); 174$manager->prio (PRIO_MAX);
173 175
174# static methods. not really. 176# static methods. not really.
175 177
176=back 178=back
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185 187
186Create a new asynchronous coroutine and return it's coroutine object 188Create a new asynchronous coroutine and return it's coroutine object
187(usually unused). When the sub returns the new coroutine is automatically 189(usually unused). When the sub returns the new coroutine is automatically
188terminated. 190terminated.
189 191
190Calling C<exit> in a coroutine will not work correctly, so do not do that. 192Calling C<exit> in a coroutine will do the same as calling exit outside
191 193the coroutine. Likewise, when the coroutine dies, the program will exit,
192When the coroutine dies, the program will exit, just as in the main 194just as it would in the main program.
193program.
194 195
195 # create a new coroutine that just prints its arguments 196 # create a new coroutine that just prints its arguments
196 async { 197 async {
197 print "@_\n"; 198 print "@_\n";
198 } 1,2,3,4; 199 } 1,2,3,4;
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210Similar to C<async>, but uses a coroutine pool, so you should not call 211Similar to C<async>, but uses a coroutine pool, so you should not call
211terminate or join (although you are allowed to), and you get a coroutine 212terminate or join (although you are allowed to), and you get a coroutine
212that might have executed other code already (which can be good or bad :). 213that might have executed other code already (which can be good or bad :).
213 214
214Also, the block is executed in an C<eval> context and a warning will be 215Also, the block is executed in an C<eval> context and a warning will be
215issued in case of an exception instead of terminating the program, as C<async> does. 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.
216 220
217The priority will be reset to C<0> after each job, otherwise the coroutine 221The priority will be reset to C<0> after each job, otherwise the coroutine
218will be re-used "as-is". 222will be re-used "as-is".
219 223
220The pool size is limited to 8 idle coroutines (this can be adjusted by 224The pool size is limited to 8 idle coroutines (this can be adjusted by
221changing $Coro::POOL_SIZE), and there can be as many non-idle coros as 225changing $Coro::POOL_SIZE), and there can be as many non-idle coros as
222required. 226required.
223 227
224If you are concerned about pooled coroutines growing a lot because a 228If you are concerned about pooled coroutines growing a lot because a
225single C<async_pool> used a lot of stackspace you can e.g. C<async_pool { 229single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
226terminate }> once per second or so to slowly replenish the 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.
227 233
228=cut 234=cut
229 235
230our $POOL_SIZE = 8; 236our $POOL_SIZE = 8;
237our $POOL_RSS = 16 * 1024;
231our @pool; 238our @async_pool;
232 239
233sub pool_handler { 240sub pool_handler {
241 my $cb;
242
234 while () { 243 while () {
235 my ($cb, @arg) = @{ delete $current->{_invoke} };
236
237 eval { 244 eval {
238 $cb->(@arg); 245 while () {
246 _pool_1 $cb;
247 &$cb;
248 _pool_2 $cb;
249 &schedule;
250 }
239 }; 251 };
252
253 last if $@ eq "\3terminate\2\n";
240 warn $@ if $@; 254 warn $@ if $@;
241 255 }
242 last if @pool >= $POOL_SIZE; 256}
243 push @pool, $current;
244
245 $current->prio (0);
246 schedule;
247 }
248}
249 257
250sub async_pool(&@) { 258sub async_pool(&@) {
251 # this is also inlined into the unlock_scheduler 259 # this is also inlined into the unlock_scheduler
252 my $coro = (pop @pool or new Coro \&pool_handler); 260 my $coro = (pop @async_pool) || new Coro \&pool_handler;
253 261
254 $coro->{_invoke} = [@_]; 262 $coro->{_invoke} = [@_];
255 $coro->ready; 263 $coro->ready;
256 264
257 $coro 265 $coro
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275 # wake up sleeping coroutine 283 # wake up sleeping coroutine
276 $current->ready; 284 $current->ready;
277 undef $current; 285 undef $current;
278 }; 286 };
279 287
280 # call schedule until event occured. 288 # call schedule until event occurred.
281 # in case we are woken up for other reasons 289 # in case we are woken up for other reasons
282 # (current still defined), loop. 290 # (current still defined), loop.
283 Coro::schedule while $current; 291 Coro::schedule while $current;
284 } 292 }
285 293
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287 295
288"Cede" to other coroutines. This function puts the current coroutine into the 296"Cede" to other coroutines. This function puts the current coroutine into the
289ready 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
290current "timeslice" to other coroutines of the same or higher priority. 298current "timeslice" to other coroutines of the same or higher priority.
291 299
300Returns true if at least one coroutine switch has happened.
301
292=item Coro::cede_notself 302=item Coro::cede_notself
293 303
294Works like cede, but is not exported by default and will cede to any 304Works like cede, but is not exported by default and will cede to any
295coroutine, regardless of priority, once. 305coroutine, regardless of priority, once.
306
307Returns true if at least one coroutine switch has happened.
296 308
297=item terminate [arg...] 309=item terminate [arg...]
298 310
299Terminates the current coroutine with the given status values (see L<cancel>). 311Terminates the current coroutine with the given status values (see L<cancel>).
300 312
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319Create a new coroutine and return it. When the sub returns the coroutine 331Create a new coroutine and return it. When the sub returns the coroutine
320automatically terminates as if C<terminate> with the returned values were 332automatically terminates as if C<terminate> with the returned values were
321called. To make the coroutine run you must first put it into the ready queue 333called. To make the coroutine run you must first put it into the ready queue
322by calling the ready method. 334by calling the ready method.
323 335
324Calling C<exit> in a coroutine will not work correctly, so do not do that. 336See C<async> for additional discussion.
325 337
326=cut 338=cut
327 339
328sub _run_coro { 340sub _run_coro {
329 terminate &{+shift}; 341 terminate &{+shift};
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452=over 4 464=over 4
453 465
454=item Coro::nready 466=item Coro::nready
455 467
456Returns the number of coroutines that are currently in the ready state, 468Returns the number of coroutines that are currently in the ready state,
457i.e. that can be swicthed to. The value C<0> means that the only runnable 469i.e. that can be switched to. The value C<0> means that the only runnable
458coroutine is the currently running one, so C<cede> would have no effect, 470coroutine is the currently running one, so C<cede> would have no effect,
459and C<schedule> would cause a deadlock unless there is an idle handler 471and C<schedule> would cause a deadlock unless there is an idle handler
460that wakes up some coroutines. 472that wakes up some coroutines.
461 473
462=item my $guard = Coro::guard { ... } 474=item my $guard = Coro::guard { ... }
463 475
464This creates and returns a guard object. Nothing happens until the objetc 476This creates and returns a guard object. Nothing happens until the object
465gets destroyed, in which case the codeblock given as argument will be 477gets destroyed, in which case the codeblock given as argument will be
466executed. This is useful to free locks or other resources in case of a 478executed. This is useful to free locks or other resources in case of a
467runtime error or when the coroutine gets canceled, as in both cases the 479runtime error or when the coroutine gets canceled, as in both cases the
468guard block will be executed. The guard object supports only one method, 480guard block will be executed. The guard object supports only one method,
469C<< ->cancel >>, which will keep the codeblock from being executed. 481C<< ->cancel >>, which will keep the codeblock from being executed.
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498This utility function takes a BLOCK or code reference and "unblocks" it, 510This utility function takes a BLOCK or code reference and "unblocks" it,
499returning the new coderef. This means that the new coderef will return 511returning the new coderef. This means that the new coderef will return
500immediately without blocking, returning nothing, while the original code 512immediately without blocking, returning nothing, while the original code
501ref will be called (with parameters) from within its own coroutine. 513ref will be called (with parameters) from within its own coroutine.
502 514
503The reason this fucntion exists is that many event libraries (such as the 515The reason this function exists is that many event libraries (such as the
504venerable L<Event|Event> module) are not coroutine-safe (a weaker form 516venerable L<Event|Event> module) are not coroutine-safe (a weaker form
505of thread-safety). This means you must not block within event callbacks, 517of thread-safety). This means you must not block within event callbacks,
506otherwise you might suffer from crashes or worse. 518otherwise you might suffer from crashes or worse.
507 519
508This function allows your callbacks to block by executing them in another 520This function allows your callbacks to block by executing them in another
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519 531
520# we create a special coro because we want to cede, 532# we create a special coro because we want to cede,
521# to reduce pressure on the coro pool (because most callbacks 533# to reduce pressure on the coro pool (because most callbacks
522# return immediately and can be reused) and because we cannot cede 534# return immediately and can be reused) and because we cannot cede
523# inside an event callback. 535# inside an event callback.
524our $unblock_scheduler = async { 536our $unblock_scheduler = new Coro sub {
525 while () { 537 while () {
526 while (my $cb = pop @unblock_queue) { 538 while (my $cb = pop @unblock_queue) {
527 # this is an inlined copy of async_pool 539 # this is an inlined copy of async_pool
528 my $coro = (pop @pool or new Coro \&pool_handler); 540 my $coro = (pop @async_pool) || new Coro \&pool_handler;
529 541
530 $coro->{_invoke} = $cb; 542 $coro->{_invoke} = $cb;
531 $coro->ready; 543 $coro->ready;
532 cede; # for short-lived callbacks, this reduces pressure on the coro pool 544 cede; # for short-lived callbacks, this reduces pressure on the coro pool
533 } 545 }
534 schedule; # sleep well 546 schedule; # sleep well
535 } 547 }
536}; 548};
549$unblock_scheduler->desc ("[unblock_sub scheduler]");
537 550
538sub unblock_sub(&) { 551sub unblock_sub(&) {
539 my $cb = shift; 552 my $cb = shift;
540 553
541 sub { 554 sub {
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554 567
555 - you must make very sure that no coro is still active on global 568 - you must make very sure that no coro is still active on global
556 destruction. very bad things might happen otherwise (usually segfaults). 569 destruction. very bad things might happen otherwise (usually segfaults).
557 570
558 - this module is not thread-safe. You should only ever use this module 571 - this module is not thread-safe. You should only ever use this module
559 from the same thread (this requirement might be losened in the future 572 from the same thread (this requirement might be loosened in the future
560 to allow per-thread schedulers, but Coro::State does not yet allow 573 to allow per-thread schedulers, but Coro::State does not yet allow
561 this). 574 this).
562 575
563=head1 SEE ALSO 576=head1 SEE ALSO
564 577

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