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20 | |
20 | |
21 | =head1 DESCRIPTION |
21 | =head1 DESCRIPTION |
22 | |
22 | |
23 | This module collection manages coroutines. Coroutines are similar |
23 | This module collection manages coroutines. Coroutines are similar |
24 | to threads but don't run in parallel at the same time even on SMP |
24 | to threads but don't run in parallel at the same time even on SMP |
25 | machines. The specific flavor of coroutine use din this module also |
25 | machines. The specific flavor of coroutine used in this module also |
26 | guarentees you that it will not switch between coroutines unless |
26 | guarantees you that it will not switch between coroutines unless |
27 | necessary, at easily-identified points in your program, so locking and |
27 | necessary, at easily-identified points in your program, so locking and |
28 | parallel access are rarely an issue, making coroutine programming much |
28 | parallel access are rarely an issue, making coroutine programming much |
29 | safer than threads programming. |
29 | safer 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 | |
51 | our $idle; # idle handler |
51 | our $idle; # idle handler |
52 | our $main; # main coroutine |
52 | our $main; # main coroutine |
53 | our $current; # current coroutine |
53 | our $current; # current coroutine |
54 | |
54 | |
55 | our $VERSION = '3.3'; |
55 | our $VERSION = '3.8'; |
56 | |
56 | |
57 | our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); |
57 | our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); |
58 | our %EXPORT_TAGS = ( |
58 | our %EXPORT_TAGS = ( |
59 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
59 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
60 | ); |
60 | ); |
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108 | |
108 | |
109 | The current coroutine (the last coroutine switched to). The initial value |
109 | The current coroutine (the last coroutine switched to). The initial value |
110 | is C<$main> (of course). |
110 | is C<$main> (of course). |
111 | |
111 | |
112 | This variable is B<strictly> I<read-only>. It is provided for performance |
112 | This variable is B<strictly> I<read-only>. It is provided for performance |
113 | reasons. If performance is not essentiel you are encouraged to use the |
113 | reasons. If performance is not essential you are encouraged to use the |
114 | C<Coro::current> function instead. |
114 | C<Coro::current> function instead. |
115 | |
115 | |
116 | =cut |
116 | =cut |
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117 | |
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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 | |
186 | Create a new asynchronous coroutine and return it's coroutine object |
188 | Create 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 |
188 | terminated. |
190 | terminated. |
189 | |
191 | |
190 | Calling C<exit> in a coroutine will not work correctly, so do not do that. |
192 | Calling C<exit> in a coroutine will do the same as calling exit outside |
191 | |
193 | the coroutine. Likewise, when the coroutine dies, the program will exit, |
192 | When the coroutine dies, the program will exit, just as in the main |
194 | just as it would in the main program. |
193 | program. |
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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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210 | Similar to C<async>, but uses a coroutine pool, so you should not call |
211 | Similar to C<async>, but uses a coroutine pool, so you should not call |
211 | terminate or join (although you are allowed to), and you get a coroutine |
212 | terminate or join (although you are allowed to), and you get a coroutine |
212 | that might have executed other code already (which can be good or bad :). |
213 | that might have executed other code already (which can be good or bad :). |
213 | |
214 | |
214 | Also, the block is executed in an C<eval> context and a warning will be |
215 | Also, the block is executed in an C<eval> context and a warning will be |
215 | issued in case of an exception instead of terminating the program, as C<async> does. |
216 | issued in case of an exception instead of terminating the program, as |
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217 | C<async> does. As the coroutine is being reused, stuff like C<on_destroy> |
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218 | will not work in the expected way, unless you call terminate or cancel, |
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219 | which somehow defeats the purpose of pooling. |
216 | |
220 | |
217 | The priority will be reset to C<0> after each job, otherwise the coroutine |
221 | The priority will be reset to C<0> after each job, otherwise the coroutine |
218 | will be re-used "as-is". |
222 | will be re-used "as-is". |
219 | |
223 | |
220 | The pool size is limited to 8 idle coroutines (this can be adjusted by |
224 | The pool size is limited to 8 idle coroutines (this can be adjusted by |
221 | changing $Coro::POOL_SIZE), and there can be as many non-idle coros as |
225 | changing $Coro::POOL_SIZE), and there can be as many non-idle coros as |
222 | required. |
226 | required. |
223 | |
227 | |
224 | If you are concerned about pooled coroutines growing a lot because a |
228 | If you are concerned about pooled coroutines growing a lot because a |
225 | single C<async_pool> used a lot of stackspace you can e.g. C<async_pool { |
229 | single C<async_pool> used a lot of stackspace you can e.g. C<async_pool |
226 | terminate }> once per second or so to slowly replenish the pool. |
230 | { terminate }> once per second or so to slowly replenish the pool. In |
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231 | addition to that, when the stacks used by a handler grows larger than 16kb |
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232 | (adjustable with $Coro::POOL_RSS) it will also exit. |
227 | |
233 | |
228 | =cut |
234 | =cut |
229 | |
235 | |
230 | our $POOL_SIZE = 8; |
236 | our $POOL_SIZE = 8; |
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237 | our $POOL_RSS = 16 * 1024; |
231 | our @pool; |
238 | our @async_pool; |
232 | |
239 | |
233 | sub pool_handler { |
240 | sub pool_handler { |
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241 | my $cb; |
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242 | |
234 | while () { |
243 | while () { |
235 | my ($cb, @arg) = @{ delete $current->{_invoke} }; |
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236 | |
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237 | eval { |
244 | eval { |
238 | $cb->(@arg); |
245 | while () { |
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246 | _pool_1 $cb; |
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247 | &$cb; |
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248 | _pool_2 $cb; |
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249 | &schedule; |
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250 | } |
239 | }; |
251 | }; |
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252 | |
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253 | last if $@ eq "\3terminate\2\n"; |
240 | warn $@ if $@; |
254 | warn $@ if $@; |
241 | |
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242 | last if @pool >= $POOL_SIZE; |
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243 | push @pool, $current; |
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244 | |
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245 | $current->prio (0); |
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246 | schedule; |
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247 | } |
255 | } |
248 | } |
256 | } |
249 | |
257 | |
250 | sub async_pool(&@) { |
258 | sub 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 |
289 | ready queue and calls C<schedule>, which has the effect of giving up the |
297 | ready queue and calls C<schedule>, which has the effect of giving up the |
290 | current "timeslice" to other coroutines of the same or higher priority. |
298 | current "timeslice" to other coroutines of the same or higher priority. |
291 | |
299 | |
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300 | Returns true if at least one coroutine switch has happened. |
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301 | |
292 | =item Coro::cede_notself |
302 | =item Coro::cede_notself |
293 | |
303 | |
294 | Works like cede, but is not exported by default and will cede to any |
304 | Works like cede, but is not exported by default and will cede to any |
295 | coroutine, regardless of priority, once. |
305 | coroutine, regardless of priority, once. |
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306 | |
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307 | Returns true if at least one coroutine switch has happened. |
296 | |
308 | |
297 | =item terminate [arg...] |
309 | =item terminate [arg...] |
298 | |
310 | |
299 | Terminates the current coroutine with the given status values (see L<cancel>). |
311 | Terminates the current coroutine with the given status values (see L<cancel>). |
300 | |
312 | |
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319 | Create a new coroutine and return it. When the sub returns the coroutine |
331 | Create a new coroutine and return it. When the sub returns the coroutine |
320 | automatically terminates as if C<terminate> with the returned values were |
332 | automatically terminates as if C<terminate> with the returned values were |
321 | called. To make the coroutine run you must first put it into the ready queue |
333 | called. To make the coroutine run you must first put it into the ready queue |
322 | by calling the ready method. |
334 | by calling the ready method. |
323 | |
335 | |
324 | Calling C<exit> in a coroutine will not work correctly, so do not do that. |
336 | See C<async> for additional discussion. |
325 | |
337 | |
326 | =cut |
338 | =cut |
327 | |
339 | |
328 | sub _run_coro { |
340 | sub _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 | |
456 | Returns the number of coroutines that are currently in the ready state, |
468 | Returns the number of coroutines that are currently in the ready state, |
457 | i.e. that can be swicthed to. The value C<0> means that the only runnable |
469 | i.e. that can be switched to. The value C<0> means that the only runnable |
458 | coroutine is the currently running one, so C<cede> would have no effect, |
470 | coroutine is the currently running one, so C<cede> would have no effect, |
459 | and C<schedule> would cause a deadlock unless there is an idle handler |
471 | and C<schedule> would cause a deadlock unless there is an idle handler |
460 | that wakes up some coroutines. |
472 | that wakes up some coroutines. |
461 | |
473 | |
462 | =item my $guard = Coro::guard { ... } |
474 | =item my $guard = Coro::guard { ... } |
463 | |
475 | |
464 | This creates and returns a guard object. Nothing happens until the objetc |
476 | This creates and returns a guard object. Nothing happens until the object |
465 | gets destroyed, in which case the codeblock given as argument will be |
477 | gets destroyed, in which case the codeblock given as argument will be |
466 | executed. This is useful to free locks or other resources in case of a |
478 | executed. This is useful to free locks or other resources in case of a |
467 | runtime error or when the coroutine gets canceled, as in both cases the |
479 | runtime error or when the coroutine gets canceled, as in both cases the |
468 | guard block will be executed. The guard object supports only one method, |
480 | guard block will be executed. The guard object supports only one method, |
469 | C<< ->cancel >>, which will keep the codeblock from being executed. |
481 | C<< ->cancel >>, which will keep the codeblock from being executed. |
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498 | This utility function takes a BLOCK or code reference and "unblocks" it, |
510 | This utility function takes a BLOCK or code reference and "unblocks" it, |
499 | returning the new coderef. This means that the new coderef will return |
511 | returning the new coderef. This means that the new coderef will return |
500 | immediately without blocking, returning nothing, while the original code |
512 | immediately without blocking, returning nothing, while the original code |
501 | ref will be called (with parameters) from within its own coroutine. |
513 | ref will be called (with parameters) from within its own coroutine. |
502 | |
514 | |
503 | The reason this fucntion exists is that many event libraries (such as the |
515 | The reason this function exists is that many event libraries (such as the |
504 | venerable L<Event|Event> module) are not coroutine-safe (a weaker form |
516 | venerable L<Event|Event> module) are not coroutine-safe (a weaker form |
505 | of thread-safety). This means you must not block within event callbacks, |
517 | of thread-safety). This means you must not block within event callbacks, |
506 | otherwise you might suffer from crashes or worse. |
518 | otherwise you might suffer from crashes or worse. |
507 | |
519 | |
508 | This function allows your callbacks to block by executing them in another |
520 | This 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. |
524 | our $unblock_scheduler = async { |
536 | our $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 | }; |
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549 | $unblock_scheduler->desc ("[unblock_sub scheduler]"); |
537 | |
550 | |
538 | sub unblock_sub(&) { |
551 | sub 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 | |