1 | =head1 NAME |
1 | =head1 NAME |
2 | |
2 | |
3 | Coro - coroutine process abstraction |
3 | Coro - the only real threads in perl |
4 | |
4 | |
5 | =head1 SYNOPSIS |
5 | =head1 SYNOPSIS |
6 | |
6 | |
7 | use Coro; |
7 | use Coro; |
8 | |
8 | |
… | |
… | |
26 | $locked = 1; |
26 | $locked = 1; |
27 | $lock->up; |
27 | $lock->up; |
28 | |
28 | |
29 | =head1 DESCRIPTION |
29 | =head1 DESCRIPTION |
30 | |
30 | |
31 | This module collection manages coroutines. Coroutines are similar to |
31 | For a tutorial-style introduction, please read the L<Coro::Intro> |
32 | threads but don't (in general) run in parallel at the same time even |
32 | manpage. This manpage mainly contains reference information. |
33 | on SMP machines. The specific flavor of coroutine used in this module |
|
|
34 | also guarantees you that it will not switch between coroutines unless |
|
|
35 | necessary, at easily-identified points in your program, so locking and |
|
|
36 | parallel access are rarely an issue, making coroutine programming much |
|
|
37 | safer and easier than threads programming. |
|
|
38 | |
33 | |
39 | Unlike a normal perl program, however, coroutines allow you to have |
34 | This module collection manages continuations in general, most often |
40 | multiple running interpreters that share data, which is especially useful |
35 | in the form of cooperative threads (also called coroutines in the |
41 | to code pseudo-parallel processes and for event-based programming, such as |
36 | documentation). They are similar to kernel threads but don't (in general) |
42 | multiple HTTP-GET requests running concurrently. See L<Coro::AnyEvent> to |
37 | run in parallel at the same time even on SMP machines. The specific flavor |
43 | learn more. |
38 | of thread offered by this module also guarantees you that it will not |
|
|
39 | switch between threads unless necessary, at easily-identified points in |
|
|
40 | your program, so locking and parallel access are rarely an issue, making |
|
|
41 | thread programming much safer and easier than using other thread models. |
44 | |
42 | |
45 | Coroutines are also useful because Perl has no support for threads (the so |
43 | Unlike the so-called "Perl threads" (which are not actually real threads |
46 | called "threads" that perl offers are nothing more than the (bad) process |
44 | but only the windows process emulation ported to unix), Coro provides a |
47 | emulation coming from the Windows platform: On standard operating systems |
45 | full shared address space, which makes communication between threads |
48 | they serve no purpose whatsoever, except by making your programs slow and |
46 | very easy. And threads are fast, too: disabling the Windows process |
49 | making them use a lot of memory. Best disable them when building perl, or |
47 | emulation code in your perl and using Coro can easily result in a two to |
50 | aks your software vendor/distributor to do it for you). |
48 | four times speed increase for your programs. |
51 | |
49 | |
|
|
50 | Coro achieves that by supporting multiple running interpreters that share |
|
|
51 | data, which is especially useful to code pseudo-parallel processes and |
|
|
52 | for event-based programming, such as multiple HTTP-GET requests running |
|
|
53 | concurrently. See L<Coro::AnyEvent> to learn more on how to integrate Coro |
|
|
54 | into an event-based environment. |
|
|
55 | |
52 | In this module, coroutines are defined as "callchain + lexical variables + |
56 | In this module, a thread is defined as "callchain + lexical variables + |
53 | @_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain, |
57 | @_ + $_ + $@ + $/ + C stack), that is, a thread has its own callchain, |
54 | its own set of lexicals and its own set of perls most important global |
58 | its own set of lexicals and its own set of perls most important global |
55 | variables (see L<Coro::State> for more configuration). |
59 | variables (see L<Coro::State> for more configuration and background info). |
|
|
60 | |
|
|
61 | See also the C<SEE ALSO> section at the end of this document - the Coro |
|
|
62 | module family is quite large. |
56 | |
63 | |
57 | =cut |
64 | =cut |
58 | |
65 | |
59 | package Coro; |
66 | package Coro; |
60 | |
67 | |
… | |
… | |
67 | |
74 | |
68 | our $idle; # idle handler |
75 | our $idle; # idle handler |
69 | our $main; # main coroutine |
76 | our $main; # main coroutine |
70 | our $current; # current coroutine |
77 | our $current; # current coroutine |
71 | |
78 | |
72 | our $VERSION = 5.0; |
79 | our $VERSION = 5.13; |
73 | |
80 | |
74 | our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); |
81 | our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); |
75 | our %EXPORT_TAGS = ( |
82 | our %EXPORT_TAGS = ( |
76 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
83 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
77 | ); |
84 | ); |
78 | our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready)); |
85 | our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready)); |
79 | |
86 | |
|
|
87 | =head1 GLOBAL VARIABLES |
|
|
88 | |
80 | =over 4 |
89 | =over 4 |
81 | |
90 | |
82 | =item $Coro::main |
91 | =item $Coro::main |
83 | |
92 | |
84 | This variable stores the coroutine object that represents the main |
93 | This variable stores the coroutine object that represents the main |
… | |
… | |
105 | sub current() { $current } # [DEPRECATED] |
114 | sub current() { $current } # [DEPRECATED] |
106 | |
115 | |
107 | =item $Coro::idle |
116 | =item $Coro::idle |
108 | |
117 | |
109 | This variable is mainly useful to integrate Coro into event loops. It is |
118 | This variable is mainly useful to integrate Coro into event loops. It is |
110 | usually better to rely on L<Coro::AnyEvent> or LC<Coro::EV>, as this is |
119 | usually better to rely on L<Coro::AnyEvent> or L<Coro::EV>, as this is |
111 | pretty low-level functionality. |
120 | pretty low-level functionality. |
112 | |
121 | |
113 | This variable stores a callback that is called whenever the scheduler |
122 | This variable stores either a coroutine or a callback. |
|
|
123 | |
|
|
124 | If it is a callback, the it is called whenever the scheduler finds no |
114 | finds no ready coroutines to run. The default implementation prints |
125 | ready coroutines to run. The default implementation prints "FATAL: |
115 | "FATAL: deadlock detected" and exits, because the program has no other way |
126 | deadlock detected" and exits, because the program has no other way to |
116 | to continue. |
127 | continue. |
117 | |
128 | |
|
|
129 | If it is a coroutine object, then this object will be readied (without |
|
|
130 | invoking any ready hooks, however) when the scheduler finds no other ready |
|
|
131 | coroutines to run. |
|
|
132 | |
118 | This hook is overwritten by modules such as C<Coro::Timer> and |
133 | This hook is overwritten by modules such as C<Coro::EV> and |
119 | C<Coro::AnyEvent> to wait on an external event that hopefully wake up a |
134 | C<Coro::AnyEvent> to wait on an external event that hopefully wake up a |
120 | coroutine so the scheduler can run it. |
135 | coroutine so the scheduler can run it. |
121 | |
136 | |
122 | Note that the callback I<must not>, under any circumstances, block |
137 | Note that the callback I<must not>, under any circumstances, block |
123 | the current coroutine. Normally, this is achieved by having an "idle |
138 | the current coroutine. Normally, this is achieved by having an "idle |
124 | coroutine" that calls the event loop and then blocks again, and then |
139 | coroutine" that calls the event loop and then blocks again, and then |
125 | readying that coroutine in the idle handler. |
140 | readying that coroutine in the idle handler, or by simply placing the idle |
|
|
141 | coroutine in this variable. |
126 | |
142 | |
127 | See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this |
143 | See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this |
128 | technique. |
144 | technique. |
129 | |
145 | |
130 | Please note that if your callback recursively invokes perl (e.g. for event |
146 | Please note that if your callback recursively invokes perl (e.g. for event |
… | |
… | |
135 | $idle = sub { |
151 | $idle = sub { |
136 | require Carp; |
152 | require Carp; |
137 | Carp::croak ("FATAL: deadlock detected"); |
153 | Carp::croak ("FATAL: deadlock detected"); |
138 | }; |
154 | }; |
139 | |
155 | |
140 | sub _cancel { |
|
|
141 | my ($self) = @_; |
|
|
142 | |
|
|
143 | # free coroutine data and mark as destructed |
|
|
144 | $self->_destroy |
|
|
145 | or return; |
|
|
146 | |
|
|
147 | # call all destruction callbacks |
|
|
148 | $_->(@{$self->{_status}}) |
|
|
149 | for @{ delete $self->{_on_destroy} || [] }; |
|
|
150 | } |
|
|
151 | |
|
|
152 | # this coroutine is necessary because a coroutine |
156 | # this coroutine is necessary because a coroutine |
153 | # cannot destroy itself. |
157 | # cannot destroy itself. |
154 | my @destroy; |
158 | our @destroy; |
155 | my $manager; |
159 | our $manager; |
156 | |
160 | |
157 | $manager = new Coro sub { |
161 | $manager = new Coro sub { |
158 | while () { |
162 | while () { |
159 | (shift @destroy)->_cancel |
163 | Coro::_cancel shift @destroy |
160 | while @destroy; |
164 | while @destroy; |
161 | |
165 | |
162 | &schedule; |
166 | &schedule; |
163 | } |
167 | } |
164 | }; |
168 | }; |
165 | $manager->{desc} = "[coro manager]"; |
169 | $manager->{desc} = "[coro manager]"; |
166 | $manager->prio (PRIO_MAX); |
170 | $manager->prio (PRIO_MAX); |
167 | |
171 | |
168 | =back |
172 | =back |
169 | |
173 | |
170 | =head2 SIMPLE COROUTINE CREATION |
174 | =head1 SIMPLE COROUTINE CREATION |
171 | |
175 | |
172 | =over 4 |
176 | =over 4 |
173 | |
177 | |
174 | =item async { ... } [@args...] |
178 | =item async { ... } [@args...] |
175 | |
179 | |
176 | Create a new coroutine and return it's coroutine object (usually |
180 | Create a new coroutine and return its coroutine object (usually |
177 | unused). The coroutine will be put into the ready queue, so |
181 | unused). The coroutine will be put into the ready queue, so |
178 | it will start running automatically on the next scheduler run. |
182 | it will start running automatically on the next scheduler run. |
179 | |
183 | |
180 | The first argument is a codeblock/closure that should be executed in the |
184 | The first argument is a codeblock/closure that should be executed in the |
181 | coroutine. When it returns argument returns the coroutine is automatically |
185 | coroutine. When it returns argument returns the coroutine is automatically |
… | |
… | |
212 | Similar to C<async>, but uses a coroutine pool, so you should not call |
216 | Similar to C<async>, but uses a coroutine pool, so you should not call |
213 | terminate or join on it (although you are allowed to), and you get a |
217 | terminate or join on it (although you are allowed to), and you get a |
214 | coroutine that might have executed other code already (which can be good |
218 | coroutine that might have executed other code already (which can be good |
215 | or bad :). |
219 | or bad :). |
216 | |
220 | |
217 | On the plus side, this function is faster than creating (and destroying) |
221 | On the plus side, this function is about twice as fast as creating (and |
218 | a completly new coroutine, so if you need a lot of generic coroutines in |
222 | destroying) a completely new coroutine, so if you need a lot of generic |
219 | quick successsion, use C<async_pool>, not C<async>. |
223 | coroutines in quick successsion, use C<async_pool>, not C<async>. |
220 | |
224 | |
221 | The code block is executed in an C<eval> context and a warning will be |
225 | The code block is executed in an C<eval> context and a warning will be |
222 | issued in case of an exception instead of terminating the program, as |
226 | issued in case of an exception instead of terminating the program, as |
223 | C<async> does. As the coroutine is being reused, stuff like C<on_destroy> |
227 | C<async> does. As the coroutine is being reused, stuff like C<on_destroy> |
224 | will not work in the expected way, unless you call terminate or cancel, |
228 | will not work in the expected way, unless you call terminate or cancel, |
… | |
… | |
237 | coros as required. |
241 | coros as required. |
238 | |
242 | |
239 | If you are concerned about pooled coroutines growing a lot because a |
243 | If you are concerned about pooled coroutines growing a lot because a |
240 | single C<async_pool> used a lot of stackspace you can e.g. C<async_pool |
244 | single C<async_pool> used a lot of stackspace you can e.g. C<async_pool |
241 | { terminate }> once per second or so to slowly replenish the pool. In |
245 | { terminate }> once per second or so to slowly replenish the pool. In |
242 | addition to that, when the stacks used by a handler grows larger than 16kb |
246 | addition to that, when the stacks used by a handler grows larger than 32kb |
243 | (adjustable via $Coro::POOL_RSS) it will also be destroyed. |
247 | (adjustable via $Coro::POOL_RSS) it will also be destroyed. |
244 | |
248 | |
245 | =cut |
249 | =cut |
246 | |
250 | |
247 | our $POOL_SIZE = 8; |
251 | our $POOL_SIZE = 8; |
248 | our $POOL_RSS = 16 * 1024; |
252 | our $POOL_RSS = 32 * 1024; |
249 | our @async_pool; |
253 | our @async_pool; |
250 | |
254 | |
251 | sub pool_handler { |
255 | sub pool_handler { |
252 | my $cb; |
|
|
253 | |
|
|
254 | while () { |
256 | while () { |
255 | eval { |
257 | eval { |
256 | while () { |
258 | &{&_pool_handler} while 1; |
257 | _pool_1 $cb; |
|
|
258 | &$cb; |
|
|
259 | _pool_2 $cb; |
|
|
260 | &schedule; |
|
|
261 | } |
|
|
262 | }; |
259 | }; |
263 | |
260 | |
264 | if ($@) { |
|
|
265 | last if $@ eq "\3async_pool terminate\2\n"; |
|
|
266 | warn $@; |
261 | warn $@ if $@; |
267 | } |
|
|
268 | } |
262 | } |
269 | } |
|
|
270 | |
|
|
271 | sub async_pool(&@) { |
|
|
272 | # this is also inlined into the unblock_scheduler |
|
|
273 | my $coro = (pop @async_pool) || new Coro \&pool_handler; |
|
|
274 | |
|
|
275 | $coro->{_invoke} = [@_]; |
|
|
276 | $coro->ready; |
|
|
277 | |
|
|
278 | $coro |
|
|
279 | } |
263 | } |
280 | |
264 | |
281 | =back |
265 | =back |
282 | |
266 | |
283 | =head2 STATIC METHODS |
267 | =head1 STATIC METHODS |
284 | |
268 | |
285 | Static methods are actually functions that operate on the current coroutine. |
269 | Static methods are actually functions that implicitly operate on the |
|
|
270 | current coroutine. |
286 | |
271 | |
287 | =over 4 |
272 | =over 4 |
288 | |
273 | |
289 | =item schedule |
274 | =item schedule |
290 | |
275 | |
… | |
… | |
305 | >> on that once some event happens, and last you call C<schedule> to put |
290 | >> on that once some event happens, and last you call C<schedule> to put |
306 | yourself to sleep. Note that a lot of things can wake your coroutine up, |
291 | yourself to sleep. Note that a lot of things can wake your coroutine up, |
307 | so you need to check whether the event indeed happened, e.g. by storing the |
292 | so you need to check whether the event indeed happened, e.g. by storing the |
308 | status in a variable. |
293 | status in a variable. |
309 | |
294 | |
310 | The canonical way to wait on external events is this: |
295 | See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks. |
311 | |
|
|
312 | { |
|
|
313 | # remember current coroutine |
|
|
314 | my $current = $Coro::current; |
|
|
315 | |
|
|
316 | # register a hypothetical event handler |
|
|
317 | on_event_invoke sub { |
|
|
318 | # wake up sleeping coroutine |
|
|
319 | $current->ready; |
|
|
320 | undef $current; |
|
|
321 | }; |
|
|
322 | |
|
|
323 | # call schedule until event occurred. |
|
|
324 | # in case we are woken up for other reasons |
|
|
325 | # (current still defined), loop. |
|
|
326 | Coro::schedule while $current; |
|
|
327 | } |
|
|
328 | |
296 | |
329 | =item cede |
297 | =item cede |
330 | |
298 | |
331 | "Cede" to other coroutines. This function puts the current coroutine into |
299 | "Cede" to other coroutines. This function puts the current coroutine into |
332 | the ready queue and calls C<schedule>, which has the effect of giving |
300 | the ready queue and calls C<schedule>, which has the effect of giving |
… | |
… | |
347 | Terminates the current coroutine with the given status values (see L<cancel>). |
315 | Terminates the current coroutine with the given status values (see L<cancel>). |
348 | |
316 | |
349 | =item killall |
317 | =item killall |
350 | |
318 | |
351 | Kills/terminates/cancels all coroutines except the currently running |
319 | Kills/terminates/cancels all coroutines except the currently running |
352 | one. This is useful after a fork, either in the child or the parent, as |
320 | one. This can be useful after a fork, either in the child or the parent, |
353 | usually only one of them should inherit the running coroutines. |
321 | as usually only one of them should inherit the running coroutines. |
|
|
322 | |
|
|
323 | Note that in the implementation, destructors run as normal, making this |
|
|
324 | function not so useful after a fork. Future versions of this function |
|
|
325 | might try to free resources without running any code. |
354 | |
326 | |
355 | Note that while this will try to free some of the main programs resources, |
327 | Note that while this will try to free some of the main programs resources, |
356 | you cannot free all of them, so if a coroutine that is not the main |
328 | you cannot free all of them, so if a coroutine that is not the main |
357 | program calls this function, there will be some one-time resource leak. |
329 | program calls this function, there will be some one-time resource leak. |
358 | |
330 | |
359 | =cut |
331 | =cut |
360 | |
|
|
361 | sub terminate { |
|
|
362 | $current->cancel (@_); |
|
|
363 | } |
|
|
364 | |
332 | |
365 | sub killall { |
333 | sub killall { |
366 | for (Coro::State::list) { |
334 | for (Coro::State::list) { |
367 | $_->cancel |
335 | $_->cancel |
368 | if $_ != $current && UNIVERSAL::isa $_, "Coro"; |
336 | if $_ != $current && UNIVERSAL::isa $_, "Coro"; |
369 | } |
337 | } |
370 | } |
338 | } |
371 | |
339 | |
372 | =back |
340 | =back |
373 | |
341 | |
374 | =head2 COROUTINE METHODS |
342 | =head1 COROUTINE OBJECT METHODS |
375 | |
343 | |
376 | These are the methods you can call on coroutine objects (or to create |
344 | These are the methods you can call on coroutine objects (or to create |
377 | them). |
345 | them). |
378 | |
346 | |
379 | =over 4 |
347 | =over 4 |
… | |
… | |
388 | See C<async> and C<Coro::State::new> for additional info about the |
356 | See C<async> and C<Coro::State::new> for additional info about the |
389 | coroutine environment. |
357 | coroutine environment. |
390 | |
358 | |
391 | =cut |
359 | =cut |
392 | |
360 | |
393 | sub _run_coro { |
361 | sub _coro_run { |
394 | terminate &{+shift}; |
362 | terminate &{+shift}; |
395 | } |
|
|
396 | |
|
|
397 | sub new { |
|
|
398 | my $class = shift; |
|
|
399 | |
|
|
400 | $class->SUPER::new (\&_run_coro, @_) |
|
|
401 | } |
363 | } |
402 | |
364 | |
403 | =item $success = $coroutine->ready |
365 | =item $success = $coroutine->ready |
404 | |
366 | |
405 | Put the given coroutine into the end of its ready queue (there is one |
367 | Put the given coroutine into the end of its ready queue (there is one |
… | |
… | |
422 | |
384 | |
423 | =cut |
385 | =cut |
424 | |
386 | |
425 | sub cancel { |
387 | sub cancel { |
426 | my $self = shift; |
388 | my $self = shift; |
427 | $self->{_status} = [@_]; |
|
|
428 | |
389 | |
429 | if ($current == $self) { |
390 | if ($current == $self) { |
430 | push @destroy, $self; |
391 | terminate @_; |
431 | $manager->ready; |
|
|
432 | &schedule while 1; |
|
|
433 | } else { |
392 | } else { |
|
|
393 | $self->{_status} = [@_]; |
434 | $self->_cancel; |
394 | $self->_cancel; |
435 | } |
395 | } |
436 | } |
396 | } |
437 | |
397 | |
|
|
398 | =item $coroutine->schedule_to |
|
|
399 | |
|
|
400 | Puts the current coroutine to sleep (like C<Coro::schedule>), but instead |
|
|
401 | of continuing with the next coro from the ready queue, always switch to |
|
|
402 | the given coroutine object (regardless of priority etc.). The readyness |
|
|
403 | state of that coroutine isn't changed. |
|
|
404 | |
|
|
405 | This is an advanced method for special cases - I'd love to hear about any |
|
|
406 | uses for this one. |
|
|
407 | |
|
|
408 | =item $coroutine->cede_to |
|
|
409 | |
|
|
410 | Like C<schedule_to>, but puts the current coroutine into the ready |
|
|
411 | queue. This has the effect of temporarily switching to the given |
|
|
412 | coroutine, and continuing some time later. |
|
|
413 | |
|
|
414 | This is an advanced method for special cases - I'd love to hear about any |
|
|
415 | uses for this one. |
|
|
416 | |
438 | =item $coroutine->throw ([$scalar]) |
417 | =item $coroutine->throw ([$scalar]) |
439 | |
418 | |
440 | If C<$throw> is specified and defined, it will be thrown as an exception |
419 | If C<$throw> is specified and defined, it will be thrown as an exception |
441 | inside the coroutine at the next convenient point in time (usually after |
420 | inside the coroutine at the next convenient point in time. Otherwise |
442 | it gains control at the next schedule/transfer/cede). Otherwise clears the |
|
|
443 | exception object. |
421 | clears the exception object. |
|
|
422 | |
|
|
423 | Coro will check for the exception each time a schedule-like-function |
|
|
424 | returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down |
|
|
425 | >>, C<< Coro::Handle->readable >> and so on. Most of these functions |
|
|
426 | detect this case and return early in case an exception is pending. |
444 | |
427 | |
445 | The exception object will be thrown "as is" with the specified scalar in |
428 | The exception object will be thrown "as is" with the specified scalar in |
446 | C<$@>, i.e. if it is a string, no line number or newline will be appended |
429 | C<$@>, i.e. if it is a string, no line number or newline will be appended |
447 | (unlike with C<die>). |
430 | (unlike with C<die>). |
448 | |
431 | |
… | |
… | |
536 | my $old = $_[0]{desc}; |
519 | my $old = $_[0]{desc}; |
537 | $_[0]{desc} = $_[1] if @_ > 1; |
520 | $_[0]{desc} = $_[1] if @_ > 1; |
538 | $old; |
521 | $old; |
539 | } |
522 | } |
540 | |
523 | |
|
|
524 | sub transfer { |
|
|
525 | require Carp; |
|
|
526 | Carp::croak ("You must not call ->transfer on Coro objects. Use Coro::State objects or the ->schedule_to method. Caught"); |
|
|
527 | } |
|
|
528 | |
541 | =back |
529 | =back |
542 | |
530 | |
543 | =head2 GLOBAL FUNCTIONS |
531 | =head1 GLOBAL FUNCTIONS |
544 | |
532 | |
545 | =over 4 |
533 | =over 4 |
546 | |
534 | |
547 | =item Coro::nready |
535 | =item Coro::nready |
548 | |
536 | |
… | |
… | |
553 | would cause a deadlock unless there is an idle handler that wakes up some |
541 | would cause a deadlock unless there is an idle handler that wakes up some |
554 | coroutines. |
542 | coroutines. |
555 | |
543 | |
556 | =item my $guard = Coro::guard { ... } |
544 | =item my $guard = Coro::guard { ... } |
557 | |
545 | |
558 | This creates and returns a guard object. Nothing happens until the object |
546 | This function still exists, but is deprecated. Please use the |
559 | gets destroyed, in which case the codeblock given as argument will be |
547 | C<Guard::guard> function instead. |
560 | executed. This is useful to free locks or other resources in case of a |
|
|
561 | runtime error or when the coroutine gets canceled, as in both cases the |
|
|
562 | guard block will be executed. The guard object supports only one method, |
|
|
563 | C<< ->cancel >>, which will keep the codeblock from being executed. |
|
|
564 | |
548 | |
565 | Example: set some flag and clear it again when the coroutine gets canceled |
|
|
566 | or the function returns: |
|
|
567 | |
|
|
568 | sub do_something { |
|
|
569 | my $guard = Coro::guard { $busy = 0 }; |
|
|
570 | $busy = 1; |
|
|
571 | |
|
|
572 | # do something that requires $busy to be true |
|
|
573 | } |
|
|
574 | |
|
|
575 | =cut |
549 | =cut |
576 | |
550 | |
577 | sub guard(&) { |
551 | BEGIN { *guard = \&Guard::guard } |
578 | bless \(my $cb = $_[0]), "Coro::guard" |
|
|
579 | } |
|
|
580 | |
|
|
581 | sub Coro::guard::cancel { |
|
|
582 | ${$_[0]} = sub { }; |
|
|
583 | } |
|
|
584 | |
|
|
585 | sub Coro::guard::DESTROY { |
|
|
586 | ${$_[0]}->(); |
|
|
587 | } |
|
|
588 | |
|
|
589 | |
552 | |
590 | =item unblock_sub { ... } |
553 | =item unblock_sub { ... } |
591 | |
554 | |
592 | This utility function takes a BLOCK or code reference and "unblocks" it, |
555 | This utility function takes a BLOCK or code reference and "unblocks" it, |
593 | returning a new coderef. Unblocking means that calling the new coderef |
556 | returning a new coderef. Unblocking means that calling the new coderef |
… | |
… | |
595 | original code ref will be called (with parameters) from within another |
558 | original code ref will be called (with parameters) from within another |
596 | coroutine. |
559 | coroutine. |
597 | |
560 | |
598 | The reason this function exists is that many event libraries (such as the |
561 | The reason this function exists is that many event libraries (such as the |
599 | venerable L<Event|Event> module) are not coroutine-safe (a weaker form |
562 | venerable L<Event|Event> module) are not coroutine-safe (a weaker form |
600 | of thread-safety). This means you must not block within event callbacks, |
563 | of reentrancy). This means you must not block within event callbacks, |
601 | otherwise you might suffer from crashes or worse. The only event library |
564 | otherwise you might suffer from crashes or worse. The only event library |
602 | currently known that is safe to use without C<unblock_sub> is L<EV>. |
565 | currently known that is safe to use without C<unblock_sub> is L<EV>. |
603 | |
566 | |
604 | This function allows your callbacks to block by executing them in another |
567 | This function allows your callbacks to block by executing them in another |
605 | coroutine where it is safe to block. One example where blocking is handy |
568 | coroutine where it is safe to block. One example where blocking is handy |
… | |
… | |
628 | # return immediately and can be reused) and because we cannot cede |
591 | # return immediately and can be reused) and because we cannot cede |
629 | # inside an event callback. |
592 | # inside an event callback. |
630 | our $unblock_scheduler = new Coro sub { |
593 | our $unblock_scheduler = new Coro sub { |
631 | while () { |
594 | while () { |
632 | while (my $cb = pop @unblock_queue) { |
595 | while (my $cb = pop @unblock_queue) { |
633 | # this is an inlined copy of async_pool |
596 | &async_pool (@$cb); |
634 | my $coro = (pop @async_pool) || new Coro \&pool_handler; |
|
|
635 | |
597 | |
636 | $coro->{_invoke} = $cb; |
|
|
637 | $coro->ready; |
|
|
638 | cede; # for short-lived callbacks, this reduces pressure on the coro pool |
598 | # for short-lived callbacks, this reduces pressure on the coro pool |
|
|
599 | # as the chance is very high that the async_poll coro will be back |
|
|
600 | # in the idle state when cede returns |
|
|
601 | cede; |
639 | } |
602 | } |
640 | schedule; # sleep well |
603 | schedule; # sleep well |
641 | } |
604 | } |
642 | }; |
605 | }; |
643 | $unblock_scheduler->{desc} = "[unblock_sub scheduler]"; |
606 | $unblock_scheduler->{desc} = "[unblock_sub scheduler]"; |
… | |
… | |
649 | unshift @unblock_queue, [$cb, @_]; |
612 | unshift @unblock_queue, [$cb, @_]; |
650 | $unblock_scheduler->ready; |
613 | $unblock_scheduler->ready; |
651 | } |
614 | } |
652 | } |
615 | } |
653 | |
616 | |
|
|
617 | =item $cb = Coro::rouse_cb |
|
|
618 | |
|
|
619 | Create and return a "rouse callback". That's a code reference that, |
|
|
620 | when called, will remember a copy of its arguments and notify the owner |
|
|
621 | coroutine of the callback. |
|
|
622 | |
|
|
623 | See the next function. |
|
|
624 | |
|
|
625 | =item @args = Coro::rouse_wait [$cb] |
|
|
626 | |
|
|
627 | Wait for the specified rouse callback (or the last one that was created in |
|
|
628 | this coroutine). |
|
|
629 | |
|
|
630 | As soon as the callback is invoked (or when the callback was invoked |
|
|
631 | before C<rouse_wait>), it will return the arguments originally passed to |
|
|
632 | the rouse callback. |
|
|
633 | |
|
|
634 | See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example. |
|
|
635 | |
654 | =back |
636 | =back |
655 | |
637 | |
656 | =cut |
638 | =cut |
657 | |
639 | |
658 | 1; |
640 | 1; |
|
|
641 | |
|
|
642 | =head1 HOW TO WAIT FOR A CALLBACK |
|
|
643 | |
|
|
644 | It is very common for a coroutine to wait for some callback to be |
|
|
645 | called. This occurs naturally when you use coroutines in an otherwise |
|
|
646 | event-based program, or when you use event-based libraries. |
|
|
647 | |
|
|
648 | These typically register a callback for some event, and call that callback |
|
|
649 | when the event occured. In a coroutine, however, you typically want to |
|
|
650 | just wait for the event, simplyifying things. |
|
|
651 | |
|
|
652 | For example C<< AnyEvent->child >> registers a callback to be called when |
|
|
653 | a specific child has exited: |
|
|
654 | |
|
|
655 | my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... }); |
|
|
656 | |
|
|
657 | But from withina coroutine, you often just want to write this: |
|
|
658 | |
|
|
659 | my $status = wait_for_child $pid; |
|
|
660 | |
|
|
661 | Coro offers two functions specifically designed to make this easy, |
|
|
662 | C<Coro::rouse_cb> and C<Coro::rouse_wait>. |
|
|
663 | |
|
|
664 | The first function, C<rouse_cb>, generates and returns a callback that, |
|
|
665 | when invoked, will save its arguments and notify the coroutine that |
|
|
666 | created the callback. |
|
|
667 | |
|
|
668 | The second function, C<rouse_wait>, waits for the callback to be called |
|
|
669 | (by calling C<schedule> to go to sleep) and returns the arguments |
|
|
670 | originally passed to the callback. |
|
|
671 | |
|
|
672 | Using these functions, it becomes easy to write the C<wait_for_child> |
|
|
673 | function mentioned above: |
|
|
674 | |
|
|
675 | sub wait_for_child($) { |
|
|
676 | my ($pid) = @_; |
|
|
677 | |
|
|
678 | my $watcher = AnyEvent->child (pid => $pid, cb => Coro::rouse_cb); |
|
|
679 | |
|
|
680 | my ($rpid, $rstatus) = Coro::rouse_wait; |
|
|
681 | $rstatus |
|
|
682 | } |
|
|
683 | |
|
|
684 | In the case where C<rouse_cb> and C<rouse_wait> are not flexible enough, |
|
|
685 | you can roll your own, using C<schedule>: |
|
|
686 | |
|
|
687 | sub wait_for_child($) { |
|
|
688 | my ($pid) = @_; |
|
|
689 | |
|
|
690 | # store the current coroutine in $current, |
|
|
691 | # and provide result variables for the closure passed to ->child |
|
|
692 | my $current = $Coro::current; |
|
|
693 | my ($done, $rstatus); |
|
|
694 | |
|
|
695 | # pass a closure to ->child |
|
|
696 | my $watcher = AnyEvent->child (pid => $pid, cb => sub { |
|
|
697 | $rstatus = $_[1]; # remember rstatus |
|
|
698 | $done = 1; # mark $rstatus as valud |
|
|
699 | }); |
|
|
700 | |
|
|
701 | # wait until the closure has been called |
|
|
702 | schedule while !$done; |
|
|
703 | |
|
|
704 | $rstatus |
|
|
705 | } |
|
|
706 | |
659 | |
707 | |
660 | =head1 BUGS/LIMITATIONS |
708 | =head1 BUGS/LIMITATIONS |
661 | |
709 | |
662 | =over 4 |
710 | =over 4 |
663 | |
711 | |
… | |
… | |
669 | fix your libc and use a saner backend. |
717 | fix your libc and use a saner backend. |
670 | |
718 | |
671 | =item perl process emulation ("threads") |
719 | =item perl process emulation ("threads") |
672 | |
720 | |
673 | This module is not perl-pseudo-thread-safe. You should only ever use this |
721 | This module is not perl-pseudo-thread-safe. You should only ever use this |
674 | module from the same thread (this requirement might be removed in the |
722 | module from the first thread (this requirement might be removed in the |
675 | future to allow per-thread schedulers, but Coro::State does not yet allow |
723 | future to allow per-thread schedulers, but Coro::State does not yet allow |
676 | this). I recommend disabling thread support and using processes, as having |
724 | this). I recommend disabling thread support and using processes, as having |
677 | the windows process emulation enabled under unix roughly halves perl |
725 | the windows process emulation enabled under unix roughly halves perl |
678 | performance, even when not used. |
726 | performance, even when not used. |
679 | |
727 | |
… | |
… | |
696 | |
744 | |
697 | Debugging: L<Coro::Debug>. |
745 | Debugging: L<Coro::Debug>. |
698 | |
746 | |
699 | Support/Utility: L<Coro::Specific>, L<Coro::Util>. |
747 | Support/Utility: L<Coro::Specific>, L<Coro::Util>. |
700 | |
748 | |
701 | Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>. |
749 | Locking and IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, |
|
|
750 | L<Coro::SemaphoreSet>, L<Coro::RWLock>. |
702 | |
751 | |
703 | IO/Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>. |
752 | I/O and Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>. |
704 | |
753 | |
705 | Compatibility: L<Coro::LWP>, L<Coro::BDB>, L<Coro::Storable>, L<Coro::Select>. |
754 | Compatibility with other modules: L<Coro::LWP> (but see also L<AnyEvent::HTTP> for |
|
|
755 | a better-working alternative), L<Coro::BDB>, L<Coro::Storable>, |
|
|
756 | L<Coro::Select>. |
706 | |
757 | |
707 | XS API: L<Coro::MakeMaker>. |
758 | XS API: L<Coro::MakeMaker>. |
708 | |
759 | |
709 | Low level Configuration, Coroutine Environment: L<Coro::State>. |
760 | Low level Configuration, Thread Environment, Continuations: L<Coro::State>. |
710 | |
761 | |
711 | =head1 AUTHOR |
762 | =head1 AUTHOR |
712 | |
763 | |
713 | Marc Lehmann <schmorp@schmorp.de> |
764 | Marc Lehmann <schmorp@schmorp.de> |
714 | http://home.schmorp.de/ |
765 | http://home.schmorp.de/ |