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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 $VERSION = '3.7'; |
56 | |
56 | |
57 | our @EXPORT = qw(async cede schedule terminate current unblock_sub); |
57 | our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); |
58 | our %EXPORT_TAGS = ( |
58 | our %EXPORT_TAGS = ( |
59 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
59 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
60 | ); |
60 | ); |
61 | our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready)); |
61 | our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready)); |
62 | |
62 | |
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108 | |
108 | |
109 | The current coroutine (the last coroutine switched to). The initial value |
109 | The current coroutine (the last coroutine switched to). The initial value |
110 | is C<$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; |
199 | |
200 | |
200 | =cut |
201 | =cut |
201 | |
202 | |
202 | sub async(&@) { |
203 | sub async(&@) { |
203 | my $pid = new Coro @_; |
204 | my $coro = new Coro @_; |
204 | $pid->ready; |
205 | $coro->ready; |
205 | $pid |
206 | $coro |
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207 | } |
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208 | |
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209 | =item async_pool { ... } [@args...] |
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210 | |
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211 | Similar to C<async>, but uses a coroutine pool, so you should not call |
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212 | terminate or join (although you are allowed to), and you get a coroutine |
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213 | that might have executed other code already (which can be good or bad :). |
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214 | |
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215 | Also, the block is executed in an C<eval> context and a warning will be |
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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. |
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220 | |
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221 | The priority will be reset to C<0> after each job, otherwise the coroutine |
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222 | will be re-used "as-is". |
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223 | |
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224 | The pool size is limited to 8 idle coroutines (this can be adjusted by |
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225 | changing $Coro::POOL_SIZE), and there can be as many non-idle coros as |
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226 | required. |
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227 | |
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228 | If you are concerned about pooled coroutines growing a lot because a |
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229 | single C<async_pool> used a lot of stackspace you can e.g. C<async_pool |
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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::MAX_POOL_RSS) it will also exit. |
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233 | |
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234 | =cut |
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235 | |
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236 | our $POOL_SIZE = 8; |
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237 | our $MAX_POOL_RSS = 16 * 1024; |
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238 | our @pool; |
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239 | |
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240 | sub pool_handler { |
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241 | while () { |
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242 | $current->{desc} = "[async_pool]"; |
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243 | |
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244 | eval { |
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245 | my ($cb, @arg) = @{ delete $current->{_invoke} or return }; |
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246 | $cb->(@arg); |
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247 | }; |
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248 | warn $@ if $@; |
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249 | |
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250 | last if @pool >= $POOL_SIZE || $current->rss >= $MAX_POOL_RSS; |
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251 | |
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252 | push @pool, $current; |
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253 | $current->{desc} = "[async_pool idle]"; |
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254 | $current->save (Coro::State::SAVE_DEF); |
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255 | $current->prio (0); |
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256 | schedule; |
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257 | } |
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258 | } |
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259 | |
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260 | sub async_pool(&@) { |
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261 | # this is also inlined into the unlock_scheduler |
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262 | my $coro = (pop @pool) || new Coro \&pool_handler;; |
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263 | |
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264 | $coro->{_invoke} = [@_]; |
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265 | $coro->ready; |
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266 | |
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267 | $coro |
206 | } |
268 | } |
207 | |
269 | |
208 | =item schedule |
270 | =item schedule |
209 | |
271 | |
210 | Calls the scheduler. Please note that the current coroutine will not be put |
272 | Calls the scheduler. Please note that the current coroutine will not be put |
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223 | # wake up sleeping coroutine |
285 | # wake up sleeping coroutine |
224 | $current->ready; |
286 | $current->ready; |
225 | undef $current; |
287 | undef $current; |
226 | }; |
288 | }; |
227 | |
289 | |
228 | # call schedule until event occured. |
290 | # call schedule until event occurred. |
229 | # in case we are woken up for other reasons |
291 | # in case we are woken up for other reasons |
230 | # (current still defined), loop. |
292 | # (current still defined), loop. |
231 | Coro::schedule while $current; |
293 | Coro::schedule while $current; |
232 | } |
294 | } |
233 | |
295 | |
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235 | |
297 | |
236 | "Cede" to other coroutines. This function puts the current coroutine into the |
298 | "Cede" to other coroutines. This function puts the current coroutine into the |
237 | ready queue and calls C<schedule>, which has the effect of giving up the |
299 | ready queue and calls C<schedule>, which has the effect of giving up the |
238 | current "timeslice" to other coroutines of the same or higher priority. |
300 | current "timeslice" to other coroutines of the same or higher priority. |
239 | |
301 | |
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302 | Returns true if at least one coroutine switch has happened. |
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303 | |
240 | =item Coro::cede_notself |
304 | =item Coro::cede_notself |
241 | |
305 | |
242 | Works like cede, but is not exported by default and will cede to any |
306 | Works like cede, but is not exported by default and will cede to any |
243 | coroutine, regardless of priority, once. |
307 | coroutine, regardless of priority, once. |
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308 | |
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309 | Returns true if at least one coroutine switch has happened. |
244 | |
310 | |
245 | =item terminate [arg...] |
311 | =item terminate [arg...] |
246 | |
312 | |
247 | Terminates the current coroutine with the given status values (see L<cancel>). |
313 | Terminates the current coroutine with the given status values (see L<cancel>). |
248 | |
314 | |
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267 | Create a new coroutine and return it. When the sub returns the coroutine |
333 | Create a new coroutine and return it. When the sub returns the coroutine |
268 | automatically terminates as if C<terminate> with the returned values were |
334 | automatically terminates as if C<terminate> with the returned values were |
269 | called. To make the coroutine run you must first put it into the ready queue |
335 | called. To make the coroutine run you must first put it into the ready queue |
270 | by calling the ready method. |
336 | by calling the ready method. |
271 | |
337 | |
272 | Calling C<exit> in a coroutine will not work correctly, so do not do that. |
338 | See C<async> for additional discussion. |
273 | |
339 | |
274 | =cut |
340 | =cut |
275 | |
341 | |
276 | sub _run_coro { |
342 | sub _run_coro { |
277 | terminate &{+shift}; |
343 | terminate &{+shift}; |
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400 | =over 4 |
466 | =over 4 |
401 | |
467 | |
402 | =item Coro::nready |
468 | =item Coro::nready |
403 | |
469 | |
404 | Returns the number of coroutines that are currently in the ready state, |
470 | Returns the number of coroutines that are currently in the ready state, |
405 | i.e. that can be swicthed to. The value C<0> means that the only runnable |
471 | i.e. that can be switched to. The value C<0> means that the only runnable |
406 | coroutine is the currently running one, so C<cede> would have no effect, |
472 | coroutine is the currently running one, so C<cede> would have no effect, |
407 | and C<schedule> would cause a deadlock unless there is an idle handler |
473 | and C<schedule> would cause a deadlock unless there is an idle handler |
408 | that wakes up some coroutines. |
474 | that wakes up some coroutines. |
409 | |
475 | |
410 | =item my $guard = Coro::guard { ... } |
476 | =item my $guard = Coro::guard { ... } |
411 | |
477 | |
412 | This creates and returns a guard object. Nothing happens until the objetc |
478 | This creates and returns a guard object. Nothing happens until the object |
413 | gets destroyed, in which case the codeblock given as argument will be |
479 | gets destroyed, in which case the codeblock given as argument will be |
414 | executed. This is useful to free locks or other resources in case of a |
480 | executed. This is useful to free locks or other resources in case of a |
415 | runtime error or when the coroutine gets canceled, as in both cases the |
481 | runtime error or when the coroutine gets canceled, as in both cases the |
416 | guard block will be executed. The guard object supports only one method, |
482 | guard block will be executed. The guard object supports only one method, |
417 | C<< ->cancel >>, which will keep the codeblock from being executed. |
483 | C<< ->cancel >>, which will keep the codeblock from being executed. |
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446 | This utility function takes a BLOCK or code reference and "unblocks" it, |
512 | This utility function takes a BLOCK or code reference and "unblocks" it, |
447 | returning the new coderef. This means that the new coderef will return |
513 | returning the new coderef. This means that the new coderef will return |
448 | immediately without blocking, returning nothing, while the original code |
514 | immediately without blocking, returning nothing, while the original code |
449 | ref will be called (with parameters) from within its own coroutine. |
515 | ref will be called (with parameters) from within its own coroutine. |
450 | |
516 | |
451 | The reason this fucntion exists is that many event libraries (such as the |
517 | The reason this function exists is that many event libraries (such as the |
452 | venerable L<Event|Event> module) are not coroutine-safe (a weaker form |
518 | venerable L<Event|Event> module) are not coroutine-safe (a weaker form |
453 | of thread-safety). This means you must not block within event callbacks, |
519 | of thread-safety). This means you must not block within event callbacks, |
454 | otherwise you might suffer from crashes or worse. |
520 | otherwise you might suffer from crashes or worse. |
455 | |
521 | |
456 | This function allows your callbacks to block by executing them in another |
522 | This function allows your callbacks to block by executing them in another |
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461 | In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when |
527 | In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when |
462 | creating event callbacks that want to block. |
528 | creating event callbacks that want to block. |
463 | |
529 | |
464 | =cut |
530 | =cut |
465 | |
531 | |
466 | our @unblock_pool; |
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467 | our @unblock_queue; |
532 | our @unblock_queue; |
468 | our $UNBLOCK_POOL_SIZE = 2; |
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469 | |
533 | |
470 | sub unblock_handler_ { |
534 | # we create a special coro because we want to cede, |
471 | while () { |
535 | # to reduce pressure on the coro pool (because most callbacks |
472 | my ($cb, @arg) = @{ delete $Coro::current->{arg} }; |
536 | # return immediately and can be reused) and because we cannot cede |
473 | $cb->(@arg); |
537 | # inside an event callback. |
474 | |
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475 | last if @unblock_pool >= $UNBLOCK_POOL_SIZE; |
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476 | push @unblock_pool, $Coro::current; |
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477 | schedule; |
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478 | } |
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479 | } |
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480 | |
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481 | our $unblock_scheduler = async { |
538 | our $unblock_scheduler = new Coro sub { |
482 | while () { |
539 | while () { |
483 | while (my $cb = pop @unblock_queue) { |
540 | while (my $cb = pop @unblock_queue) { |
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541 | # this is an inlined copy of async_pool |
484 | my $handler = (pop @unblock_pool or new Coro \&unblock_handler_); |
542 | my $coro = (pop @pool or new Coro \&pool_handler); |
485 | $handler->{arg} = $cb; |
543 | |
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544 | $coro->{_invoke} = $cb; |
486 | $handler->ready; |
545 | $coro->ready; |
487 | cede; |
546 | cede; # for short-lived callbacks, this reduces pressure on the coro pool |
488 | } |
547 | } |
489 | |
548 | schedule; # sleep well |
490 | schedule; |
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491 | } |
549 | } |
492 | }; |
550 | }; |
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551 | $unblock_scheduler->desc ("[unblock_sub scheduler]"); |
493 | |
552 | |
494 | sub unblock_sub(&) { |
553 | sub unblock_sub(&) { |
495 | my $cb = shift; |
554 | my $cb = shift; |
496 | |
555 | |
497 | sub { |
556 | sub { |
498 | push @unblock_queue, [$cb, @_]; |
557 | unshift @unblock_queue, [$cb, @_]; |
499 | $unblock_scheduler->ready; |
558 | $unblock_scheduler->ready; |
500 | } |
559 | } |
501 | } |
560 | } |
502 | |
561 | |
503 | =back |
562 | =back |
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510 | |
569 | |
511 | - you must make very sure that no coro is still active on global |
570 | - you must make very sure that no coro is still active on global |
512 | destruction. very bad things might happen otherwise (usually segfaults). |
571 | destruction. very bad things might happen otherwise (usually segfaults). |
513 | |
572 | |
514 | - this module is not thread-safe. You should only ever use this module |
573 | - this module is not thread-safe. You should only ever use this module |
515 | from the same thread (this requirement might be losened in the future |
574 | from the same thread (this requirement might be loosened in the future |
516 | to allow per-thread schedulers, but Coro::State does not yet allow |
575 | to allow per-thread schedulers, but Coro::State does not yet allow |
517 | this). |
576 | this). |
518 | |
577 | |
519 | =head1 SEE ALSO |
578 | =head1 SEE ALSO |
520 | |
579 | |