… | |
… | |
14 | cede; # yield to coro |
14 | cede; # yield to coro |
15 | print "3\n"; |
15 | print "3\n"; |
16 | cede; # and again |
16 | cede; # and again |
17 | |
17 | |
18 | # use locking |
18 | # use locking |
19 | use Coro::Semaphore; |
|
|
20 | my $lock = new Coro::Semaphore; |
19 | my $lock = new Coro::Semaphore; |
21 | my $locked; |
20 | my $locked; |
22 | |
21 | |
23 | $lock->down; |
22 | $lock->down; |
24 | $locked = 1; |
23 | $locked = 1; |
… | |
… | |
67 | CORO THREAD LIFE CYCLE |
66 | CORO THREAD LIFE CYCLE |
68 | During the long and exciting (or not) life of a coro thread, it goes |
67 | During the long and exciting (or not) life of a coro thread, it goes |
69 | through a number of states: |
68 | through a number of states: |
70 | |
69 | |
71 | 1. Creation |
70 | 1. Creation |
72 | The first thing in the life of a coro thread is it's creation - |
71 | The first thing in the life of a coro thread is its creation - |
73 | obviously. The typical way to create a thread is to call the "async |
72 | obviously. The typical way to create a thread is to call the "async |
74 | BLOCK" function: |
73 | BLOCK" function: |
75 | |
74 | |
76 | async { |
75 | async { |
77 | # thread code goes here |
76 | # thread code goes here |
… | |
… | |
84 | } 1, 2, 3; |
83 | } 1, 2, 3; |
85 | |
84 | |
86 | This creates a new coro thread and puts it into the ready queue, |
85 | This creates a new coro thread and puts it into the ready queue, |
87 | meaning it will run as soon as the CPU is free for it. |
86 | meaning it will run as soon as the CPU is free for it. |
88 | |
87 | |
89 | "async" will return a coro object - you can store this for future |
88 | "async" will return a Coro object - you can store this for future |
90 | reference or ignore it, the thread itself will keep a reference to |
89 | reference or ignore it - a thread that is running, ready to run or |
91 | it's thread object - threads are alive on their own. |
90 | waiting for some event is alive on its own. |
92 | |
91 | |
93 | Another way to create a thread is to call the "new" constructor with |
92 | Another way to create a thread is to call the "new" constructor with |
94 | a code-reference: |
93 | a code-reference: |
95 | |
94 | |
96 | new Coro sub { |
95 | new Coro sub { |
… | |
… | |
123 | A lot can happen after the coro thread has started running. Quite |
122 | A lot can happen after the coro thread has started running. Quite |
124 | usually, it will not run to the end in one go (because you could use |
123 | usually, it will not run to the end in one go (because you could use |
125 | a function instead), but it will give up the CPU regularly because |
124 | a function instead), but it will give up the CPU regularly because |
126 | it waits for external events. |
125 | it waits for external events. |
127 | |
126 | |
128 | As long as a coro thread runs, it's coro object is available in the |
127 | As long as a coro thread runs, its Coro object is available in the |
129 | global variable $Coro::current. |
128 | global variable $Coro::current. |
130 | |
129 | |
131 | The low-level way to give up the CPU is to call the scheduler, which |
130 | The low-level way to give up the CPU is to call the scheduler, which |
132 | selects a new coro thread to run: |
131 | selects a new coro thread to run: |
133 | |
132 | |
… | |
… | |
187 | |
186 | |
188 | async { |
187 | async { |
189 | Coro::terminate "return value 1", "return value 2"; |
188 | Coro::terminate "return value 1", "return value 2"; |
190 | }; |
189 | }; |
191 | |
190 | |
192 | And yet another way is to "->cancel" the coro thread from another |
191 | Yet another way is to "->cancel" (or "->safe_cancel") the coro |
193 | thread: |
192 | thread from another thread: |
194 | |
193 | |
195 | my $coro = async { |
194 | my $coro = async { |
196 | exit 1; |
195 | exit 1; |
197 | }; |
196 | }; |
198 | |
197 | |
199 | $coro->cancel; # an also accept values for ->join to retrieve |
198 | $coro->cancel; # also accepts values for ->join to retrieve |
200 | |
199 | |
201 | Cancellation *can* be dangerous - it's a bit like calling "exit" |
200 | Cancellation *can* be dangerous - it's a bit like calling "exit" |
202 | without actually exiting, and might leave C libraries and XS modules |
201 | without actually exiting, and might leave C libraries and XS modules |
203 | in a weird state. Unlike other thread implementations, however, Coro |
202 | in a weird state. Unlike other thread implementations, however, Coro |
204 | is exceptionally safe with regards to cancellation, as perl will |
203 | is exceptionally safe with regards to cancellation, as perl will |
205 | always be in a consistent state. |
204 | always be in a consistent state, and for those cases where you want |
|
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205 | to do truly marvellous things with your coro while it is being |
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206 | cancelled - that is, make sure all cleanup code is executed from the |
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207 | thread being cancelled - there is even a "->safe_cancel" method. |
206 | |
208 | |
207 | So, cancelling a thread that runs in an XS event loop might not be |
209 | So, cancelling a thread that runs in an XS event loop might not be |
208 | the best idea, but any other combination that deals with perl only |
210 | the best idea, but any other combination that deals with perl only |
209 | (cancelling when a thread is in a "tie" method or an "AUTOLOAD" for |
211 | (cancelling when a thread is in a "tie" method or an "AUTOLOAD" for |
210 | example) is safe. |
212 | example) is safe. |
211 | |
213 | |
|
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214 | Last not least, a coro thread object that isn't referenced is |
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215 | "->cancel"'ed automatically - just like other objects in Perl. This |
|
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216 | is not such a common case, however - a running thread is referencedy |
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217 | by $Coro::current, a thread ready to run is referenced by the ready |
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218 | queue, a thread waiting on a lock or semaphore is referenced by |
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219 | being in some wait list and so on. But a thread that isn't in any of |
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220 | those queues gets cancelled: |
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221 | |
|
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222 | async { |
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223 | schedule; # cede to other coros, don't go into the ready queue |
|
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224 | }; |
|
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225 | |
|
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226 | cede; |
|
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227 | # now the async above is destroyed, as it is not referenced by anything. |
|
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228 | |
|
|
229 | A slightly embellished example might make it clearer: |
|
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230 | |
|
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231 | async { |
|
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232 | my $guard = Guard::guard { print "destroyed\n" }; |
|
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233 | schedule while 1; |
|
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234 | }; |
|
|
235 | |
|
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236 | cede; |
|
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237 | |
|
|
238 | Superficially one might not expect any output - since the "async" |
|
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239 | implements an endless loop, the $guard will not be cleaned up. |
|
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240 | However, since the thread object returned by "async" is not stored |
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241 | anywhere, the thread is initially referenced because it is in the |
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242 | ready queue, when it runs it is referenced by $Coro::current, but |
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243 | when it calls "schedule", it gets "cancel"ed causing the guard |
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244 | object to be destroyed (see the next section), and printing its |
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245 | message. |
|
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246 | |
|
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247 | If this seems a bit drastic, remember that this only happens when |
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248 | nothing references the thread anymore, which means there is no way |
|
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249 | to further execute it, ever. The only options at this point are |
|
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250 | leaking the thread, or cleaning it up, which brings us to... |
|
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251 | |
212 | 5. Cleanup |
252 | 5. Cleanup |
213 | Threads will allocate various resources. Most but not all will be |
253 | Threads will allocate various resources. Most but not all will be |
214 | returned when a thread terminates, during clean-up. |
254 | returned when a thread terminates, during clean-up. |
215 | |
255 | |
216 | Cleanup is quite similar to throwing an uncaught exception: perl |
256 | Cleanup is quite similar to throwing an uncaught exception: perl |
217 | will work it's way up through all subroutine calls and blocks. On |
257 | will work its way up through all subroutine calls and blocks. On its |
218 | it's way, it will release all "my" variables, undo all "local"'s and |
258 | way, it will release all "my" variables, undo all "local"'s and free |
219 | free any other resources truly local to the thread. |
259 | any other resources truly local to the thread. |
220 | |
260 | |
221 | So, a common way to free resources is to keep them referenced only |
261 | So, a common way to free resources is to keep them referenced only |
222 | by my variables: |
262 | by my variables: |
223 | |
263 | |
224 | async { |
264 | async { |
… | |
… | |
233 | |
273 | |
234 | my $sem = new Coro::Semaphore; |
274 | my $sem = new Coro::Semaphore; |
235 | |
275 | |
236 | async { |
276 | async { |
237 | my $lock_guard = $sem->guard; |
277 | my $lock_guard = $sem->guard; |
238 | # if we reutrn, or die or get cancelled, here, |
278 | # if we return, or die or get cancelled, here, |
239 | # then the semaphore will be "up"ed. |
279 | # then the semaphore will be "up"ed. |
240 | }; |
280 | }; |
241 | |
281 | |
242 | The "Guard::guard" function comes in handy for any custom cleanup |
282 | The "Guard::guard" function comes in handy for any custom cleanup |
243 | you might want to do: |
283 | you might want to do (but you cannot switch to other coroutines from |
|
|
284 | those code blocks): |
244 | |
285 | |
245 | async { |
286 | async { |
246 | my $window = new Gtk2::Window "toplevel"; |
287 | my $window = new Gtk2::Window "toplevel"; |
247 | # The window will not be cleaned up automatically, even when $window |
288 | # The window will not be cleaned up automatically, even when $window |
248 | # gets freed, so use a guard to ensure it's destruction |
289 | # gets freed, so use a guard to ensure its destruction |
249 | # in case of an error: |
290 | # in case of an error: |
250 | my $window_guard = Guard::guard { $window->destroy }; |
291 | my $window_guard = Guard::guard { $window->destroy }; |
251 | |
292 | |
252 | # we are safe here |
293 | # we are safe here |
253 | }; |
294 | }; |
… | |
… | |
260 | |
301 | |
261 | # if we return or die here, the description will be restored |
302 | # if we return or die here, the description will be restored |
262 | } |
303 | } |
263 | |
304 | |
264 | 6. Viva La Zombie Muerte |
305 | 6. Viva La Zombie Muerte |
265 | Even after a thread has terminated and cleaned up it's resources, |
306 | Even after a thread has terminated and cleaned up its resources, the |
266 | the coro object still is there and stores the return values of the |
307 | Coro object still is there and stores the return values of the |
267 | thread. Only in this state will the coro object be "reference |
308 | thread. |
268 | counted" in the normal perl sense: the thread code keeps a reference |
|
|
269 | to it when it is active, but not after it has terminated. |
|
|
270 | |
309 | |
271 | The means the coro object gets freed automatically when the thread |
310 | When there are no other references, it will simply be cleaned up and |
272 | has terminated and cleaned up and there arenot other references. |
311 | freed. |
273 | |
312 | |
274 | If there are, the coro object will stay around, and you can call |
313 | If there areany references, the Coro object will stay around, and |
275 | "->join" as many times as you wish to retrieve the result values: |
314 | you can call "->join" as many times as you wish to retrieve the |
|
|
315 | result values: |
276 | |
316 | |
277 | async { |
317 | async { |
278 | print "hi\n"; |
318 | print "hi\n"; |
279 | 1 |
319 | 1 |
280 | }; |
320 | }; |
… | |
… | |
300 | }; |
340 | }; |
301 | |
341 | |
302 | GLOBAL VARIABLES |
342 | GLOBAL VARIABLES |
303 | $Coro::main |
343 | $Coro::main |
304 | This variable stores the Coro object that represents the main |
344 | This variable stores the Coro object that represents the main |
305 | program. While you cna "ready" it and do most other things you can |
345 | program. While you can "ready" it and do most other things you can |
306 | do to coro, it is mainly useful to compare again $Coro::current, to |
346 | do to coro, it is mainly useful to compare again $Coro::current, to |
307 | see whether you are running in the main program or not. |
347 | see whether you are running in the main program or not. |
308 | |
348 | |
309 | $Coro::current |
349 | $Coro::current |
310 | The Coro object representing the current coro (the last coro that |
350 | The Coro object representing the current coro (the last coro that |
… | |
… | |
377 | program, as "async" does. As the coro is being reused, stuff like |
417 | program, as "async" does. As the coro is being reused, stuff like |
378 | "on_destroy" will not work in the expected way, unless you call |
418 | "on_destroy" will not work in the expected way, unless you call |
379 | terminate or cancel, which somehow defeats the purpose of pooling |
419 | terminate or cancel, which somehow defeats the purpose of pooling |
380 | (but is fine in the exceptional case). |
420 | (but is fine in the exceptional case). |
381 | |
421 | |
382 | The priority will be reset to 0 after each run, tracing will be |
422 | The priority will be reset to 0 after each run, all "swap_sv" calls |
383 | disabled, the description will be reset and the default output |
423 | will be undone, tracing will be disabled, the description will be |
384 | filehandle gets restored, so you can change all these. Otherwise the |
424 | reset and the default output filehandle gets restored, so you can |
385 | coro will be re-used "as-is": most notably if you change other |
425 | change all these. Otherwise the coro will be re-used "as-is": most |
386 | per-coro global stuff such as $/ you *must needs* revert that |
426 | notably if you change other per-coro global stuff such as $/ you |
387 | change, which is most simply done by using local as in: "local $/". |
427 | *must needs* revert that change, which is most simply done by using |
|
|
428 | local as in: "local $/". |
388 | |
429 | |
389 | The idle pool size is limited to 8 idle coros (this can be adjusted |
430 | The idle pool size is limited to 8 idle coros (this can be adjusted |
390 | by changing $Coro::POOL_SIZE), but there can be as many non-idle |
431 | by changing $Coro::POOL_SIZE), but there can be as many non-idle |
391 | coros as required. |
432 | coros as required. |
392 | |
433 | |
… | |
… | |
438 | *any* coro, regardless of priority. This is useful sometimes to |
479 | *any* coro, regardless of priority. This is useful sometimes to |
439 | ensure progress is made. |
480 | ensure progress is made. |
440 | |
481 | |
441 | terminate [arg...] |
482 | terminate [arg...] |
442 | Terminates the current coro with the given status values (see |
483 | Terminates the current coro with the given status values (see |
443 | cancel). |
484 | cancel). The values will not be copied, but referenced directly. |
444 | |
485 | |
445 | Coro::on_enter BLOCK, Coro::on_leave BLOCK |
486 | Coro::on_enter BLOCK, Coro::on_leave BLOCK |
446 | These function install enter and leave winders in the current scope. |
487 | These function install enter and leave winders in the current scope. |
447 | The enter block will be executed when on_enter is called and |
488 | The enter block will be executed when on_enter is called and |
448 | whenever the current coro is re-entered by the scheduler, while the |
489 | whenever the current coro is re-entered by the scheduler, while the |
… | |
… | |
493 | # at this place, the timezone is Antarctica/South_Pole, |
534 | # at this place, the timezone is Antarctica/South_Pole, |
494 | # without disturbing the TZ of any other coro. |
535 | # without disturbing the TZ of any other coro. |
495 | }; |
536 | }; |
496 | |
537 | |
497 | This can be used to localise about any resource (locale, uid, |
538 | This can be used to localise about any resource (locale, uid, |
498 | current working directory etc.) to a block, despite the existance of |
539 | current working directory etc.) to a block, despite the existence of |
499 | other coros. |
540 | other coros. |
500 | |
541 | |
501 | Another interesting example implements time-sliced multitasking |
542 | Another interesting example implements time-sliced multitasking |
502 | using interval timers (this could obviously be optimised, but does |
543 | using interval timers (this could obviously be optimised, but does |
503 | the job): |
544 | the job): |
… | |
… | |
509 | Coro::on_enter { |
550 | Coro::on_enter { |
510 | # on entering the thread, we set an VTALRM handler to cede |
551 | # on entering the thread, we set an VTALRM handler to cede |
511 | $SIG{VTALRM} = sub { cede }; |
552 | $SIG{VTALRM} = sub { cede }; |
512 | # and then start the interval timer |
553 | # and then start the interval timer |
513 | Time::HiRes::setitimer &Time::HiRes::ITIMER_VIRTUAL, 0.01, 0.01; |
554 | Time::HiRes::setitimer &Time::HiRes::ITIMER_VIRTUAL, 0.01, 0.01; |
514 | }; |
555 | }; |
515 | Coro::on_leave { |
556 | Coro::on_leave { |
516 | # on leaving the thread, we stop the interval timer again |
557 | # on leaving the thread, we stop the interval timer again |
517 | Time::HiRes::setitimer &Time::HiRes::ITIMER_VIRTUAL, 0, 0; |
558 | Time::HiRes::setitimer &Time::HiRes::ITIMER_VIRTUAL, 0, 0; |
518 | }; |
559 | }; |
519 | |
560 | |
520 | &{+shift}; |
561 | &{+shift}; |
521 | } |
562 | } |
522 | |
563 | |
523 | # use like this: |
564 | # use like this: |
524 | timeslice { |
565 | timeslice { |
525 | # The following is an endless loop that would normally |
566 | # The following is an endless loop that would normally |
526 | # monopolise the process. Since it runs in a timesliced |
567 | # monopolise the process. Since it runs in a timesliced |
… | |
… | |
580 | To avoid this, it is best to put a suspended coro into the ready |
621 | To avoid this, it is best to put a suspended coro into the ready |
581 | queue unconditionally, as every synchronisation mechanism must |
622 | queue unconditionally, as every synchronisation mechanism must |
582 | protect itself against spurious wakeups, and the one in the Coro |
623 | protect itself against spurious wakeups, and the one in the Coro |
583 | family certainly do that. |
624 | family certainly do that. |
584 | |
625 | |
|
|
626 | $state->is_new |
|
|
627 | Returns true iff this Coro object is "new", i.e. has never been run |
|
|
628 | yet. Those states basically consist of only the code reference to |
|
|
629 | call and the arguments, but consumes very little other resources. |
|
|
630 | New states will automatically get assigned a perl interpreter when |
|
|
631 | they are transferred to. |
|
|
632 | |
|
|
633 | $state->is_zombie |
|
|
634 | Returns true iff the Coro object has been cancelled, i.e. its |
|
|
635 | resources freed because they were "cancel"'ed, "terminate"'d, |
|
|
636 | "safe_cancel"'ed or simply went out of scope. |
|
|
637 | |
|
|
638 | The name "zombie" stems from UNIX culture, where a process that has |
|
|
639 | exited and only stores and exit status and no other resources is |
|
|
640 | called a "zombie". |
|
|
641 | |
585 | $is_ready = $coro->is_ready |
642 | $is_ready = $coro->is_ready |
586 | Returns true iff the Coro object is in the ready queue. Unless the |
643 | Returns true iff the Coro object is in the ready queue. Unless the |
587 | Coro object gets destroyed, it will eventually be scheduled by the |
644 | Coro object gets destroyed, it will eventually be scheduled by the |
588 | scheduler. |
645 | scheduler. |
589 | |
646 | |
… | |
… | |
594 | |
651 | |
595 | $is_suspended = $coro->is_suspended |
652 | $is_suspended = $coro->is_suspended |
596 | Returns true iff this Coro object has been suspended. Suspended |
653 | Returns true iff this Coro object has been suspended. Suspended |
597 | Coros will not ever be scheduled. |
654 | Coros will not ever be scheduled. |
598 | |
655 | |
599 | $coro->cancel (arg...) |
656 | $coro->cancel ($arg...) |
600 | Terminates the given Coro and makes it return the given arguments as |
657 | Terminate the given Coro thread and make it return the given |
601 | status (default: the empty list). Never returns if the Coro is the |
658 | arguments as status (default: an empty list). Never returns if the |
602 | current Coro. |
659 | Coro is the current Coro. |
|
|
660 | |
|
|
661 | This is a rather brutal way to free a coro, with some limitations - |
|
|
662 | if the thread is inside a C callback that doesn't expect to be |
|
|
663 | canceled, bad things can happen, or if the cancelled thread insists |
|
|
664 | on running complicated cleanup handlers that rely on its thread |
|
|
665 | context, things will not work. |
|
|
666 | |
|
|
667 | Any cleanup code being run (e.g. from "guard" blocks, destructors |
|
|
668 | and so on) will be run without a thread context, and is not allowed |
|
|
669 | to switch to other threads. A common mistake is to call "->cancel" |
|
|
670 | from a destructor called by die'ing inside the thread to be |
|
|
671 | cancelled for example. |
|
|
672 | |
|
|
673 | On the plus side, "->cancel" will always clean up the thread, no |
|
|
674 | matter what. If your cleanup code is complex or you want to avoid |
|
|
675 | cancelling a C-thread that doesn't know how to clean up itself, it |
|
|
676 | can be better to "->throw" an exception, or use "->safe_cancel". |
|
|
677 | |
|
|
678 | The arguments to "->cancel" are not copied, but instead will be |
|
|
679 | referenced directly (e.g. if you pass $var and after the call change |
|
|
680 | that variable, then you might change the return values passed to |
|
|
681 | e.g. "join", so don't do that). |
|
|
682 | |
|
|
683 | The resources of the Coro are usually freed (or destructed) before |
|
|
684 | this call returns, but this can be delayed for an indefinite amount |
|
|
685 | of time, as in some cases the manager thread has to run first to |
|
|
686 | actually destruct the Coro object. |
|
|
687 | |
|
|
688 | $coro->safe_cancel ($arg...) |
|
|
689 | Works mostly like "->cancel", but is inherently "safer", and |
|
|
690 | consequently, can fail with an exception in cases the thread is not |
|
|
691 | in a cancellable state. Essentially, "->safe_cancel" is a "->cancel" |
|
|
692 | with extra checks before canceling. |
|
|
693 | |
|
|
694 | It works a bit like throwing an exception that cannot be caught - |
|
|
695 | specifically, it will clean up the thread from within itself, so all |
|
|
696 | cleanup handlers (e.g. "guard" blocks) are run with full thread |
|
|
697 | context and can block if they wish. The downside is that there is no |
|
|
698 | guarantee that the thread can be cancelled when you call this |
|
|
699 | method, and therefore, it might fail. It is also considerably slower |
|
|
700 | than "cancel" or "terminate". |
|
|
701 | |
|
|
702 | A thread is in a safe-cancellable state if it either has never been |
|
|
703 | run yet, has already been canceled/terminated or otherwise |
|
|
704 | destroyed, or has no C context attached and is inside an SLF |
|
|
705 | function. |
|
|
706 | |
|
|
707 | The first two states are trivial - a thread that hasnot started or |
|
|
708 | has already finished is safe to cancel. |
|
|
709 | |
|
|
710 | The last state basically means that the thread isn't currently |
|
|
711 | inside a perl callback called from some C function (usually via some |
|
|
712 | XS modules) and isn't currently executing inside some C function |
|
|
713 | itself (via Coro's XS API). |
|
|
714 | |
|
|
715 | This call returns true when it could cancel the thread, or croaks |
|
|
716 | with an error otherwise (i.e. it either returns true or doesn't |
|
|
717 | return at all). |
|
|
718 | |
|
|
719 | Why the weird interface? Well, there are two common models on how |
|
|
720 | and when to cancel things. In the first, you have the expectation |
|
|
721 | that your coro thread can be cancelled when you want to cancel it - |
|
|
722 | if the thread isn't cancellable, this would be a bug somewhere, so |
|
|
723 | "->safe_cancel" croaks to notify of the bug. |
|
|
724 | |
|
|
725 | In the second model you sometimes want to ask nicely to cancel a |
|
|
726 | thread, but if it's not a good time, well, then don't cancel. This |
|
|
727 | can be done relatively easy like this: |
|
|
728 | |
|
|
729 | if (! eval { $coro->safe_cancel }) { |
|
|
730 | warn "unable to cancel thread: $@"; |
|
|
731 | } |
|
|
732 | |
|
|
733 | However, what you never should do is first try to cancel "safely" |
|
|
734 | and if that fails, cancel the "hard" way with "->cancel". That makes |
|
|
735 | no sense: either you rely on being able to execute cleanup code in |
|
|
736 | your thread context, or you don't. If you do, then "->safe_cancel" |
|
|
737 | is the only way, and if you don't, then "->cancel" is always faster |
|
|
738 | and more direct. |
603 | |
739 | |
604 | $coro->schedule_to |
740 | $coro->schedule_to |
605 | Puts the current coro to sleep (like "Coro::schedule"), but instead |
741 | Puts the current coro to sleep (like "Coro::schedule"), but instead |
606 | of continuing with the next coro from the ready queue, always switch |
742 | of continuing with the next coro from the ready queue, always switch |
607 | to the given coro object (regardless of priority etc.). The |
743 | to the given coro object (regardless of priority etc.). The |
… | |
… | |
624 | Otherwise clears the exception object. |
760 | Otherwise clears the exception object. |
625 | |
761 | |
626 | Coro will check for the exception each time a schedule-like-function |
762 | Coro will check for the exception each time a schedule-like-function |
627 | returns, i.e. after each "schedule", "cede", |
763 | returns, i.e. after each "schedule", "cede", |
628 | "Coro::Semaphore->down", "Coro::Handle->readable" and so on. Most of |
764 | "Coro::Semaphore->down", "Coro::Handle->readable" and so on. Most of |
629 | these functions detect this case and return early in case an |
765 | those functions (all that are part of Coro itself) detect this case |
630 | exception is pending. |
766 | and return early in case an exception is pending. |
631 | |
767 | |
632 | The exception object will be thrown "as is" with the specified |
768 | The exception object will be thrown "as is" with the specified |
633 | scalar in $@, i.e. if it is a string, no line number or newline will |
769 | scalar in $@, i.e. if it is a string, no line number or newline will |
634 | be appended (unlike with "die"). |
770 | be appended (unlike with "die"). |
635 | |
771 | |
636 | This can be used as a softer means than "cancel" to ask a coro to |
772 | This can be used as a softer means than either "cancel" or |
637 | end itself, although there is no guarantee that the exception will |
773 | "safe_cancel "to ask a coro to end itself, although there is no |
638 | lead to termination, and if the exception isn't caught it might well |
774 | guarantee that the exception will lead to termination, and if the |
639 | end the whole program. |
775 | exception isn't caught it might well end the whole program. |
640 | |
776 | |
641 | You might also think of "throw" as being the moral equivalent of |
777 | You might also think of "throw" as being the moral equivalent of |
642 | "kill"ing a coro with a signal (in this case, a scalar). |
778 | "kill"ing a coro with a signal (in this case, a scalar). |
643 | |
779 | |
644 | $coro->join |
780 | $coro->join |
645 | Wait until the coro terminates and return any values given to the |
781 | Wait until the coro terminates and return any values given to the |
646 | "terminate" or "cancel" functions. "join" can be called concurrently |
782 | "terminate" or "cancel" functions. "join" can be called concurrently |
647 | from multiple coro, and all will be resumed and given the status |
783 | from multiple threads, and all will be resumed and given the status |
648 | return once the $coro terminates. |
784 | return once the $coro terminates. |
649 | |
785 | |
650 | $coro->on_destroy (\&cb) |
786 | $coro->on_destroy (\&cb) |
651 | Registers a callback that is called when this coro thread gets |
787 | Registers a callback that is called when this coro thread gets |
652 | destroyed, but before it is joined. The callback gets passed the |
788 | destroyed, that is, after its resources have been freed but before |
|
|
789 | it is joined. The callback gets passed the terminate/cancel |
653 | terminate arguments, if any, and *must not* die, under any |
790 | arguments, if any, and *must not* die, under any circumstances. |
654 | circumstances. |
|
|
655 | |
791 | |
656 | There can be any number of "on_destroy" callbacks per coro. |
792 | There can be any number of "on_destroy" callbacks per coro, and |
|
|
793 | there is currently no way to remove a callback once added. |
657 | |
794 | |
658 | $oldprio = $coro->prio ($newprio) |
795 | $oldprio = $coro->prio ($newprio) |
659 | Sets (or gets, if the argument is missing) the priority of the coro |
796 | Sets (or gets, if the argument is missing) the priority of the coro |
660 | thread. Higher priority coro get run before lower priority coros. |
797 | thread. Higher priority coro get run before lower priority coros. |
661 | Priorities are small signed integers (currently -4 .. +3), that you |
798 | Priorities are small signed integers (currently -4 .. +3), that you |
… | |
… | |
687 | with a coro. |
824 | with a coro. |
688 | |
825 | |
689 | This method simply sets the "$coro->{desc}" member to the given |
826 | This method simply sets the "$coro->{desc}" member to the given |
690 | string. You can modify this member directly if you wish, and in |
827 | string. You can modify this member directly if you wish, and in |
691 | fact, this is often preferred to indicate major processing states |
828 | fact, this is often preferred to indicate major processing states |
692 | that cna then be seen for example in a Coro::Debug session: |
829 | that can then be seen for example in a Coro::Debug session: |
693 | |
830 | |
694 | sub my_long_function { |
831 | sub my_long_function { |
695 | local $Coro::current->{desc} = "now in my_long_function"; |
832 | local $Coro::current->{desc} = "now in my_long_function"; |
696 | ... |
833 | ... |
697 | $Coro::current->{desc} = "my_long_function: phase 1"; |
834 | $Coro::current->{desc} = "my_long_function: phase 1"; |
… | |
… | |
726 | otherwise you might suffer from crashes or worse. The only event |
863 | otherwise you might suffer from crashes or worse. The only event |
727 | library currently known that is safe to use without "unblock_sub" is |
864 | library currently known that is safe to use without "unblock_sub" is |
728 | EV (but you might still run into deadlocks if all event loops are |
865 | EV (but you might still run into deadlocks if all event loops are |
729 | blocked). |
866 | blocked). |
730 | |
867 | |
731 | Coro will try to catch you when you block in the event loop |
868 | Coro will try to catch you when you block in the event loop ("FATAL: |
732 | ("FATAL:$Coro::IDLE blocked itself"), but this is just best effort |
869 | $Coro::idle blocked itself"), but this is just best effort and only |
733 | and only works when you do not run your own event loop. |
870 | works when you do not run your own event loop. |
734 | |
871 | |
735 | This function allows your callbacks to block by executing them in |
872 | This function allows your callbacks to block by executing them in |
736 | another coro where it is safe to block. One example where blocking |
873 | another coro where it is safe to block. One example where blocking |
737 | is handy is when you use the Coro::AIO functions to save results to |
874 | is handy is when you use the Coro::AIO functions to save results to |
738 | disk, for example. |
875 | disk, for example. |
… | |
… | |
754 | $cb = rouse_cb |
891 | $cb = rouse_cb |
755 | Create and return a "rouse callback". That's a code reference that, |
892 | Create and return a "rouse callback". That's a code reference that, |
756 | when called, will remember a copy of its arguments and notify the |
893 | when called, will remember a copy of its arguments and notify the |
757 | owner coro of the callback. |
894 | owner coro of the callback. |
758 | |
895 | |
|
|
896 | Only the first invocation will store agruments and signal any waiter |
|
|
897 | - further calls will effectively be ignored, but it is ok to try. |
|
|
898 | |
759 | See the next function. |
899 | Also see the next function. |
760 | |
900 | |
761 | @args = rouse_wait [$cb] |
901 | @args = rouse_wait [$cb] |
762 | Wait for the specified rouse callback (or the last one that was |
902 | Wait for the specified rouse callback to be invoked (or if the |
763 | created in this coro). |
903 | argument is missing, use the most recently created callback in the |
|
|
904 | current coro). |
764 | |
905 | |
765 | As soon as the callback is invoked (or when the callback was invoked |
906 | As soon as the callback is invoked (or when the callback was invoked |
766 | before "rouse_wait"), it will return the arguments originally passed |
907 | before "rouse_wait"), it will return the arguments originally passed |
767 | to the rouse callback. In scalar context, that means you get the |
908 | to the rouse callback. In scalar context, that means you get the |
768 | *last* argument, just as if "rouse_wait" had a "return ($a1, $a2, |
909 | *last* argument, just as if "rouse_wait" had a "return ($a1, $a2, |
769 | $a3...)" statement at the end. |
910 | $a3...)" statement at the end. |
770 | |
911 | |
|
|
912 | You are only allowed to wait once for a given rouse callback. |
|
|
913 | |
771 | See the section HOW TO WAIT FOR A CALLBACK for an actual usage |
914 | See the section HOW TO WAIT FOR A CALLBACK for an actual usage |
772 | example. |
915 | example. |
|
|
916 | |
|
|
917 | As of Coro 6.57, you can reliably wait for a rouse callback in a |
|
|
918 | different thread than from where it was created. |
773 | |
919 | |
774 | HOW TO WAIT FOR A CALLBACK |
920 | HOW TO WAIT FOR A CALLBACK |
775 | It is very common for a coro to wait for some callback to be called. |
921 | It is very common for a coro to wait for some callback to be called. |
776 | This occurs naturally when you use coro in an otherwise event-based |
922 | This occurs naturally when you use coro in an otherwise event-based |
777 | program, or when you use event-based libraries. |
923 | program, or when you use event-based libraries. |
778 | |
924 | |
779 | These typically register a callback for some event, and call that |
925 | These typically register a callback for some event, and call that |
780 | callback when the event occured. In a coro, however, you typically want |
926 | callback when the event occurred. In a coro, however, you typically want |
781 | to just wait for the event, simplyifying things. |
927 | to just wait for the event, simplyifying things. |
782 | |
928 | |
783 | For example "AnyEvent->child" registers a callback to be called when a |
929 | For example "AnyEvent->child" registers a callback to be called when a |
784 | specific child has exited: |
930 | specific child has exited: |
785 | |
931 | |
… | |
… | |
788 | But from within a coro, you often just want to write this: |
934 | But from within a coro, you often just want to write this: |
789 | |
935 | |
790 | my $status = wait_for_child $pid; |
936 | my $status = wait_for_child $pid; |
791 | |
937 | |
792 | Coro offers two functions specifically designed to make this easy, |
938 | Coro offers two functions specifically designed to make this easy, |
793 | "Coro::rouse_cb" and "Coro::rouse_wait". |
939 | "rouse_cb" and "rouse_wait". |
794 | |
940 | |
795 | The first function, "rouse_cb", generates and returns a callback that, |
941 | The first function, "rouse_cb", generates and returns a callback that, |
796 | when invoked, will save its arguments and notify the coro that created |
942 | when invoked, will save its arguments and notify the coro that created |
797 | the callback. |
943 | the callback. |
798 | |
944 | |
… | |
… | |
804 | function mentioned above: |
950 | function mentioned above: |
805 | |
951 | |
806 | sub wait_for_child($) { |
952 | sub wait_for_child($) { |
807 | my ($pid) = @_; |
953 | my ($pid) = @_; |
808 | |
954 | |
809 | my $watcher = AnyEvent->child (pid => $pid, cb => Coro::rouse_cb); |
955 | my $watcher = AnyEvent->child (pid => $pid, cb => rouse_cb); |
810 | |
956 | |
811 | my ($rpid, $rstatus) = Coro::rouse_wait; |
957 | my ($rpid, $rstatus) = rouse_wait; |
812 | $rstatus |
958 | $rstatus |
813 | } |
959 | } |
814 | |
960 | |
815 | In the case where "rouse_cb" and "rouse_wait" are not flexible enough, |
961 | In the case where "rouse_cb" and "rouse_wait" are not flexible enough, |
816 | you can roll your own, using "schedule": |
962 | you can roll your own, using "schedule" and "ready": |
817 | |
963 | |
818 | sub wait_for_child($) { |
964 | sub wait_for_child($) { |
819 | my ($pid) = @_; |
965 | my ($pid) = @_; |
820 | |
966 | |
821 | # store the current coro in $current, |
967 | # store the current coro in $current, |
… | |
… | |
824 | my ($done, $rstatus); |
970 | my ($done, $rstatus); |
825 | |
971 | |
826 | # pass a closure to ->child |
972 | # pass a closure to ->child |
827 | my $watcher = AnyEvent->child (pid => $pid, cb => sub { |
973 | my $watcher = AnyEvent->child (pid => $pid, cb => sub { |
828 | $rstatus = $_[1]; # remember rstatus |
974 | $rstatus = $_[1]; # remember rstatus |
829 | $done = 1; # mark $rstatus as valud |
975 | $done = 1; # mark $rstatus as valid |
|
|
976 | $current->ready; # wake up the waiting thread |
830 | }); |
977 | }); |
831 | |
978 | |
832 | # wait until the closure has been called |
979 | # wait until the closure has been called |
833 | schedule while !$done; |
980 | schedule while !$done; |
834 | |
981 | |
… | |
… | |
847 | this module from the first thread (this requirement might be removed |
994 | this module from the first thread (this requirement might be removed |
848 | in the future to allow per-thread schedulers, but Coro::State does |
995 | in the future to allow per-thread schedulers, but Coro::State does |
849 | not yet allow this). I recommend disabling thread support and using |
996 | not yet allow this). I recommend disabling thread support and using |
850 | processes, as having the windows process emulation enabled under |
997 | processes, as having the windows process emulation enabled under |
851 | unix roughly halves perl performance, even when not used. |
998 | unix roughly halves perl performance, even when not used. |
|
|
999 | |
|
|
1000 | Attempts to use threads created in another emulated process will |
|
|
1001 | crash ("cleanly", with a null pointer exception). |
852 | |
1002 | |
853 | coro switching is not signal safe |
1003 | coro switching is not signal safe |
854 | You must not switch to another coro from within a signal handler |
1004 | You must not switch to another coro from within a signal handler |
855 | (only relevant with %SIG - most event libraries provide safe |
1005 | (only relevant with %SIG - most event libraries provide safe |
856 | signals), *unless* you are sure you are not interrupting a Coro |
1006 | signals), *unless* you are sure you are not interrupting a Coro |
… | |
… | |
900 | processes. What makes it so bad is that on non-windows platforms, you |
1050 | processes. What makes it so bad is that on non-windows platforms, you |
901 | can actually take advantage of custom hardware for this purpose (as |
1051 | can actually take advantage of custom hardware for this purpose (as |
902 | evidenced by the forks module, which gives you the (i-) threads API, |
1052 | evidenced by the forks module, which gives you the (i-) threads API, |
903 | just much faster). |
1053 | just much faster). |
904 | |
1054 | |
905 | Sharing data is in the i-threads model is done by transfering data |
1055 | Sharing data is in the i-threads model is done by transferring data |
906 | structures between threads using copying semantics, which is very slow - |
1056 | structures between threads using copying semantics, which is very slow - |
907 | shared data simply does not exist. Benchmarks using i-threads which are |
1057 | shared data simply does not exist. Benchmarks using i-threads which are |
908 | communication-intensive show extremely bad behaviour with i-threads (in |
1058 | communication-intensive show extremely bad behaviour with i-threads (in |
909 | fact, so bad that Coro, which cannot take direct advantage of multiple |
1059 | fact, so bad that Coro, which cannot take direct advantage of multiple |
910 | CPUs, is often orders of magnitude faster because it shares data using |
1060 | CPUs, is often orders of magnitude faster because it shares data using |
… | |
… | |
939 | |
1089 | |
940 | XS API: Coro::MakeMaker. |
1090 | XS API: Coro::MakeMaker. |
941 | |
1091 | |
942 | Low level Configuration, Thread Environment, Continuations: Coro::State. |
1092 | Low level Configuration, Thread Environment, Continuations: Coro::State. |
943 | |
1093 | |
944 | AUTHOR |
1094 | AUTHOR/SUPPORT/CONTACT |
945 | Marc Lehmann <schmorp@schmorp.de> |
1095 | Marc A. Lehmann <schmorp@schmorp.de> |
946 | http://home.schmorp.de/ |
1096 | http://software.schmorp.de/pkg/Coro.html |
947 | |
1097 | |