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 | |
9 | async { |
9 | async { |
10 | # some asynchronous thread of execution |
10 | # some asynchronous thread of execution |
|
|
11 | print "2\n"; |
|
|
12 | cede; # yield back to main |
|
|
13 | print "4\n"; |
11 | }; |
14 | }; |
12 | |
15 | print "1\n"; |
13 | # alternatively create an async process like this: |
16 | cede; # yield to coroutine |
14 | |
17 | print "3\n"; |
15 | sub some_func : Coro { |
18 | cede; # and again |
16 | # some more async code |
19 | |
17 | } |
20 | # use locking |
18 | |
21 | use Coro::Semaphore; |
19 | yield; |
22 | my $lock = new Coro::Semaphore; |
|
|
23 | my $locked; |
|
|
24 | |
|
|
25 | $lock->down; |
|
|
26 | $locked = 1; |
|
|
27 | $lock->up; |
20 | |
28 | |
21 | =head1 DESCRIPTION |
29 | =head1 DESCRIPTION |
22 | |
30 | |
|
|
31 | For a tutorial-style introduction, please read the L<Coro::Intro> |
|
|
32 | manpage. This manpage mainly contains reference information. |
|
|
33 | |
|
|
34 | This module collection manages continuations in general, most often |
|
|
35 | in the form of cooperative threads (also called coroutines in the |
|
|
36 | documentation). They are similar to kernel threads but don't (in general) |
|
|
37 | run in parallel at the same time even on SMP machines. The specific flavor |
|
|
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. |
|
|
42 | |
|
|
43 | Unlike the so-called "Perl threads" (which are not actually real threads |
|
|
44 | but only the windows process emulation ported to unix), Coro provides a |
|
|
45 | full shared address space, which makes communication between threads |
|
|
46 | very easy. And threads are fast, too: disabling the Windows process |
|
|
47 | emulation code in your perl and using Coro can easily result in a two to |
|
|
48 | four times speed increase for your programs. |
|
|
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 | |
|
|
56 | In this module, a thread is defined as "callchain + lexical variables + |
|
|
57 | @_ + $_ + $@ + $/ + C stack), that is, a thread has its own callchain, |
|
|
58 | its own set of lexicals and its own set of perls most important global |
|
|
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. |
|
|
63 | |
23 | =cut |
64 | =cut |
24 | |
65 | |
25 | package Coro; |
66 | package Coro; |
26 | |
67 | |
|
|
68 | use strict qw(vars subs); |
|
|
69 | no warnings "uninitialized"; |
|
|
70 | |
27 | use Coro::State; |
71 | use Coro::State; |
28 | |
72 | |
29 | use base Exporter; |
73 | use base qw(Coro::State Exporter); |
30 | |
74 | |
31 | $VERSION = 0.04; |
75 | our $idle; # idle handler |
|
|
76 | our $main; # main coroutine |
|
|
77 | our $current; # current coroutine |
32 | |
78 | |
33 | @EXPORT = qw(async yield schedule); |
79 | our $VERSION = 5.13; |
34 | @EXPORT_OK = qw($current); |
|
|
35 | |
80 | |
36 | { |
81 | our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); |
37 | use subs 'async'; |
82 | our %EXPORT_TAGS = ( |
|
|
83 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
|
|
84 | ); |
|
|
85 | our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready)); |
38 | |
86 | |
39 | my @async; |
87 | =head1 GLOBAL VARIABLES |
40 | |
88 | |
41 | # this way of handling attributes simply is NOT scalable ;() |
89 | =over 4 |
42 | sub import { |
90 | |
43 | Coro->export_to_level(1, @_); |
91 | =item $Coro::main |
44 | my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE}; |
92 | |
45 | *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub { |
93 | This variable stores the coroutine object that represents the main |
46 | my ($package, $ref) = (shift, shift); |
94 | program. While you cna C<ready> it and do most other things you can do to |
47 | my @attrs; |
95 | coroutines, it is mainly useful to compare again C<$Coro::current>, to see |
48 | for (@_) { |
96 | whether you are running in the main program or not. |
49 | if ($_ eq "Coro") { |
97 | |
50 | push @async, $ref; |
98 | =cut |
51 | } else { |
99 | |
52 | push @attrs, @_; |
100 | # $main is now being initialised by Coro::State |
53 | } |
101 | |
54 | } |
102 | =item $Coro::current |
55 | return $old ? $old->($package, $name, @attrs) : @attrs; |
103 | |
|
|
104 | The coroutine object representing the current coroutine (the last |
|
|
105 | coroutine that the Coro scheduler switched to). The initial value is |
|
|
106 | C<$Coro::main> (of course). |
|
|
107 | |
|
|
108 | This variable is B<strictly> I<read-only>. You can take copies of the |
|
|
109 | value stored in it and use it as any other coroutine object, but you must |
|
|
110 | not otherwise modify the variable itself. |
|
|
111 | |
|
|
112 | =cut |
|
|
113 | |
|
|
114 | sub current() { $current } # [DEPRECATED] |
|
|
115 | |
|
|
116 | =item $Coro::idle |
|
|
117 | |
|
|
118 | This variable is mainly useful to integrate Coro into event loops. It is |
|
|
119 | usually better to rely on L<Coro::AnyEvent> or L<Coro::EV>, as this is |
|
|
120 | pretty low-level functionality. |
|
|
121 | |
|
|
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 |
|
|
125 | ready coroutines to run. The default implementation prints "FATAL: |
|
|
126 | deadlock detected" and exits, because the program has no other way to |
|
|
127 | continue. |
|
|
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 | |
|
|
133 | This hook is overwritten by modules such as C<Coro::EV> and |
|
|
134 | C<Coro::AnyEvent> to wait on an external event that hopefully wake up a |
|
|
135 | coroutine so the scheduler can run it. |
|
|
136 | |
|
|
137 | Note that the callback I<must not>, under any circumstances, block |
|
|
138 | the current coroutine. Normally, this is achieved by having an "idle |
|
|
139 | coroutine" that calls the event loop and then blocks again, and then |
|
|
140 | readying that coroutine in the idle handler, or by simply placing the idle |
|
|
141 | coroutine in this variable. |
|
|
142 | |
|
|
143 | See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this |
|
|
144 | technique. |
|
|
145 | |
|
|
146 | Please note that if your callback recursively invokes perl (e.g. for event |
|
|
147 | handlers), then it must be prepared to be called recursively itself. |
|
|
148 | |
|
|
149 | =cut |
|
|
150 | |
|
|
151 | $idle = sub { |
|
|
152 | require Carp; |
|
|
153 | Carp::croak ("FATAL: deadlock detected"); |
|
|
154 | }; |
|
|
155 | |
|
|
156 | # this coroutine is necessary because a coroutine |
|
|
157 | # cannot destroy itself. |
|
|
158 | our @destroy; |
|
|
159 | our $manager; |
|
|
160 | |
|
|
161 | $manager = new Coro sub { |
|
|
162 | while () { |
|
|
163 | Coro::_cancel shift @destroy |
|
|
164 | while @destroy; |
|
|
165 | |
|
|
166 | &schedule; |
|
|
167 | } |
|
|
168 | }; |
|
|
169 | $manager->{desc} = "[coro manager]"; |
|
|
170 | $manager->prio (PRIO_MAX); |
|
|
171 | |
|
|
172 | =back |
|
|
173 | |
|
|
174 | =head1 SIMPLE COROUTINE CREATION |
|
|
175 | |
|
|
176 | =over 4 |
|
|
177 | |
|
|
178 | =item async { ... } [@args...] |
|
|
179 | |
|
|
180 | Create a new coroutine and return its coroutine object (usually |
|
|
181 | unused). The coroutine will be put into the ready queue, so |
|
|
182 | it will start running automatically on the next scheduler run. |
|
|
183 | |
|
|
184 | The first argument is a codeblock/closure that should be executed in the |
|
|
185 | coroutine. When it returns argument returns the coroutine is automatically |
|
|
186 | terminated. |
|
|
187 | |
|
|
188 | The remaining arguments are passed as arguments to the closure. |
|
|
189 | |
|
|
190 | See the C<Coro::State::new> constructor for info about the coroutine |
|
|
191 | environment in which coroutines are executed. |
|
|
192 | |
|
|
193 | Calling C<exit> in a coroutine will do the same as calling exit outside |
|
|
194 | the coroutine. Likewise, when the coroutine dies, the program will exit, |
|
|
195 | just as it would in the main program. |
|
|
196 | |
|
|
197 | If you do not want that, you can provide a default C<die> handler, or |
|
|
198 | simply avoid dieing (by use of C<eval>). |
|
|
199 | |
|
|
200 | Example: Create a new coroutine that just prints its arguments. |
|
|
201 | |
|
|
202 | async { |
|
|
203 | print "@_\n"; |
|
|
204 | } 1,2,3,4; |
|
|
205 | |
|
|
206 | =cut |
|
|
207 | |
|
|
208 | sub async(&@) { |
|
|
209 | my $coro = new Coro @_; |
|
|
210 | $coro->ready; |
|
|
211 | $coro |
|
|
212 | } |
|
|
213 | |
|
|
214 | =item async_pool { ... } [@args...] |
|
|
215 | |
|
|
216 | Similar to C<async>, but uses a coroutine pool, so you should not call |
|
|
217 | terminate or join on it (although you are allowed to), and you get a |
|
|
218 | coroutine that might have executed other code already (which can be good |
|
|
219 | or bad :). |
|
|
220 | |
|
|
221 | On the plus side, this function is about twice as fast as creating (and |
|
|
222 | destroying) a completely new coroutine, so if you need a lot of generic |
|
|
223 | coroutines in quick successsion, use C<async_pool>, not C<async>. |
|
|
224 | |
|
|
225 | The code block is executed in an C<eval> context and a warning will be |
|
|
226 | issued in case of an exception instead of terminating the program, as |
|
|
227 | C<async> does. As the coroutine is being reused, stuff like C<on_destroy> |
|
|
228 | will not work in the expected way, unless you call terminate or cancel, |
|
|
229 | which somehow defeats the purpose of pooling (but is fine in the |
|
|
230 | exceptional case). |
|
|
231 | |
|
|
232 | The priority will be reset to C<0> after each run, tracing will be |
|
|
233 | disabled, the description will be reset and the default output filehandle |
|
|
234 | gets restored, so you can change all these. Otherwise the coroutine will |
|
|
235 | be re-used "as-is": most notably if you change other per-coroutine global |
|
|
236 | stuff such as C<$/> you I<must needs> revert that change, which is most |
|
|
237 | simply done by using local as in: C<< local $/ >>. |
|
|
238 | |
|
|
239 | The idle pool size is limited to C<8> idle coroutines (this can be |
|
|
240 | adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle |
|
|
241 | coros as required. |
|
|
242 | |
|
|
243 | If you are concerned about pooled coroutines growing a lot because a |
|
|
244 | single C<async_pool> used a lot of stackspace you can e.g. C<async_pool |
|
|
245 | { terminate }> once per second or so to slowly replenish the pool. In |
|
|
246 | addition to that, when the stacks used by a handler grows larger than 32kb |
|
|
247 | (adjustable via $Coro::POOL_RSS) it will also be destroyed. |
|
|
248 | |
|
|
249 | =cut |
|
|
250 | |
|
|
251 | our $POOL_SIZE = 8; |
|
|
252 | our $POOL_RSS = 32 * 1024; |
|
|
253 | our @async_pool; |
|
|
254 | |
|
|
255 | sub pool_handler { |
|
|
256 | while () { |
|
|
257 | eval { |
|
|
258 | &{&_pool_handler} while 1; |
56 | }; |
259 | }; |
57 | } |
|
|
58 | |
260 | |
59 | sub INIT { |
261 | warn $@ if $@; |
60 | async pop @async while @async; |
|
|
61 | } |
262 | } |
62 | } |
263 | } |
63 | |
264 | |
64 | =item $main |
265 | =back |
65 | |
266 | |
66 | This coroutine represents the main program. |
267 | =head1 STATIC METHODS |
67 | |
268 | |
68 | =cut |
269 | Static methods are actually functions that implicitly operate on the |
|
|
270 | current coroutine. |
69 | |
271 | |
70 | our $main = new Coro; |
272 | =over 4 |
71 | |
273 | |
72 | =item $current |
274 | =item schedule |
73 | |
275 | |
74 | The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course). |
276 | Calls the scheduler. The scheduler will find the next coroutine that is |
|
|
277 | to be run from the ready queue and switches to it. The next coroutine |
|
|
278 | to be run is simply the one with the highest priority that is longest |
|
|
279 | in its ready queue. If there is no coroutine ready, it will clal the |
|
|
280 | C<$Coro::idle> hook. |
75 | |
281 | |
76 | =cut |
282 | Please note that the current coroutine will I<not> be put into the ready |
|
|
283 | queue, so calling this function usually means you will never be called |
|
|
284 | again unless something else (e.g. an event handler) calls C<< ->ready >>, |
|
|
285 | thus waking you up. |
77 | |
286 | |
78 | # maybe some other module used Coro::Specific before... |
287 | This makes C<schedule> I<the> generic method to use to block the current |
79 | if ($current) { |
288 | coroutine and wait for events: first you remember the current coroutine in |
80 | $main->{specific} = $current->{specific}; |
289 | a variable, then arrange for some callback of yours to call C<< ->ready |
81 | } |
290 | >> on that once some event happens, and last you call C<schedule> to put |
|
|
291 | yourself to sleep. Note that a lot of things can wake your coroutine up, |
|
|
292 | so you need to check whether the event indeed happened, e.g. by storing the |
|
|
293 | status in a variable. |
82 | |
294 | |
83 | our $current = $main; |
295 | See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks. |
84 | |
296 | |
85 | =item $idle |
297 | =item cede |
86 | |
298 | |
87 | The coroutine to switch to when no other coroutine is running. The default |
299 | "Cede" to other coroutines. This function puts the current coroutine into |
88 | implementation prints "FATAL: deadlock detected" and exits. |
300 | the ready queue and calls C<schedule>, which has the effect of giving |
|
|
301 | up the current "timeslice" to other coroutines of the same or higher |
|
|
302 | priority. Once your coroutine gets its turn again it will automatically be |
|
|
303 | resumed. |
89 | |
304 | |
90 | =cut |
305 | This function is often called C<yield> in other languages. |
91 | |
306 | |
92 | # should be done using priorities :( |
307 | =item Coro::cede_notself |
|
|
308 | |
|
|
309 | Works like cede, but is not exported by default and will cede to I<any> |
|
|
310 | coroutine, regardless of priority. This is useful sometimes to ensure |
|
|
311 | progress is made. |
|
|
312 | |
|
|
313 | =item terminate [arg...] |
|
|
314 | |
|
|
315 | Terminates the current coroutine with the given status values (see L<cancel>). |
|
|
316 | |
|
|
317 | =item killall |
|
|
318 | |
|
|
319 | Kills/terminates/cancels all coroutines except the currently running |
|
|
320 | one. This is useful after a fork, either in the child or the parent, as |
|
|
321 | usually only one of them should inherit the running coroutines. |
|
|
322 | |
|
|
323 | Note that while this will try to free some of the main programs resources, |
|
|
324 | you cannot free all of them, so if a coroutine that is not the main |
|
|
325 | program calls this function, there will be some one-time resource leak. |
|
|
326 | |
|
|
327 | =cut |
|
|
328 | |
|
|
329 | sub killall { |
|
|
330 | for (Coro::State::list) { |
|
|
331 | $_->cancel |
|
|
332 | if $_ != $current && UNIVERSAL::isa $_, "Coro"; |
|
|
333 | } |
|
|
334 | } |
|
|
335 | |
|
|
336 | =back |
|
|
337 | |
|
|
338 | =head1 COROUTINE OBJECT METHODS |
|
|
339 | |
|
|
340 | These are the methods you can call on coroutine objects (or to create |
|
|
341 | them). |
|
|
342 | |
|
|
343 | =over 4 |
|
|
344 | |
|
|
345 | =item new Coro \&sub [, @args...] |
|
|
346 | |
|
|
347 | Create a new coroutine and return it. When the sub returns, the coroutine |
|
|
348 | automatically terminates as if C<terminate> with the returned values were |
|
|
349 | called. To make the coroutine run you must first put it into the ready |
|
|
350 | queue by calling the ready method. |
|
|
351 | |
|
|
352 | See C<async> and C<Coro::State::new> for additional info about the |
|
|
353 | coroutine environment. |
|
|
354 | |
|
|
355 | =cut |
|
|
356 | |
|
|
357 | sub _coro_run { |
|
|
358 | terminate &{+shift}; |
|
|
359 | } |
|
|
360 | |
|
|
361 | =item $success = $coroutine->ready |
|
|
362 | |
|
|
363 | Put the given coroutine into the end of its ready queue (there is one |
|
|
364 | queue for each priority) and return true. If the coroutine is already in |
|
|
365 | the ready queue, do nothing and return false. |
|
|
366 | |
|
|
367 | This ensures that the scheduler will resume this coroutine automatically |
|
|
368 | once all the coroutines of higher priority and all coroutines of the same |
|
|
369 | priority that were put into the ready queue earlier have been resumed. |
|
|
370 | |
|
|
371 | =item $is_ready = $coroutine->is_ready |
|
|
372 | |
|
|
373 | Return whether the coroutine is currently the ready queue or not, |
|
|
374 | |
|
|
375 | =item $coroutine->cancel (arg...) |
|
|
376 | |
|
|
377 | Terminates the given coroutine and makes it return the given arguments as |
|
|
378 | status (default: the empty list). Never returns if the coroutine is the |
|
|
379 | current coroutine. |
|
|
380 | |
|
|
381 | =cut |
|
|
382 | |
|
|
383 | sub cancel { |
|
|
384 | my $self = shift; |
|
|
385 | |
|
|
386 | if ($current == $self) { |
|
|
387 | terminate @_; |
|
|
388 | } else { |
|
|
389 | $self->{_status} = [@_]; |
|
|
390 | $self->_cancel; |
|
|
391 | } |
|
|
392 | } |
|
|
393 | |
|
|
394 | =item $coroutine->schedule_to |
|
|
395 | |
|
|
396 | Puts the current coroutine to sleep (like C<Coro::schedule>), but instead |
|
|
397 | of continuing with the next coro from the ready queue, always switch to |
|
|
398 | the given coroutine object (regardless of priority etc.). The readyness |
|
|
399 | state of that coroutine isn't changed. |
|
|
400 | |
|
|
401 | This is an advanced method for special cases - I'd love to hear about any |
|
|
402 | uses for this one. |
|
|
403 | |
|
|
404 | =item $coroutine->cede_to |
|
|
405 | |
|
|
406 | Like C<schedule_to>, but puts the current coroutine into the ready |
|
|
407 | queue. This has the effect of temporarily switching to the given |
|
|
408 | coroutine, and continuing some time later. |
|
|
409 | |
|
|
410 | This is an advanced method for special cases - I'd love to hear about any |
|
|
411 | uses for this one. |
|
|
412 | |
|
|
413 | =item $coroutine->throw ([$scalar]) |
|
|
414 | |
|
|
415 | If C<$throw> is specified and defined, it will be thrown as an exception |
|
|
416 | inside the coroutine at the next convenient point in time. Otherwise |
|
|
417 | clears the exception object. |
|
|
418 | |
|
|
419 | Coro will check for the exception each time a schedule-like-function |
|
|
420 | returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down |
|
|
421 | >>, C<< Coro::Handle->readable >> and so on. Most of these functions |
|
|
422 | detect this case and return early in case an exception is pending. |
|
|
423 | |
|
|
424 | The exception object will be thrown "as is" with the specified scalar in |
|
|
425 | C<$@>, i.e. if it is a string, no line number or newline will be appended |
|
|
426 | (unlike with C<die>). |
|
|
427 | |
|
|
428 | This can be used as a softer means than C<cancel> to ask a coroutine to |
|
|
429 | end itself, although there is no guarantee that the exception will lead to |
|
|
430 | termination, and if the exception isn't caught it might well end the whole |
|
|
431 | program. |
|
|
432 | |
|
|
433 | You might also think of C<throw> as being the moral equivalent of |
|
|
434 | C<kill>ing a coroutine with a signal (in this case, a scalar). |
|
|
435 | |
|
|
436 | =item $coroutine->join |
|
|
437 | |
|
|
438 | Wait until the coroutine terminates and return any values given to the |
|
|
439 | C<terminate> or C<cancel> functions. C<join> can be called concurrently |
|
|
440 | from multiple coroutines, and all will be resumed and given the status |
|
|
441 | return once the C<$coroutine> terminates. |
|
|
442 | |
|
|
443 | =cut |
|
|
444 | |
|
|
445 | sub join { |
|
|
446 | my $self = shift; |
|
|
447 | |
|
|
448 | unless ($self->{_status}) { |
|
|
449 | my $current = $current; |
|
|
450 | |
|
|
451 | push @{$self->{_on_destroy}}, sub { |
|
|
452 | $current->ready; |
|
|
453 | undef $current; |
|
|
454 | }; |
|
|
455 | |
|
|
456 | &schedule while $current; |
|
|
457 | } |
|
|
458 | |
|
|
459 | wantarray ? @{$self->{_status}} : $self->{_status}[0]; |
|
|
460 | } |
|
|
461 | |
|
|
462 | =item $coroutine->on_destroy (\&cb) |
|
|
463 | |
|
|
464 | Registers a callback that is called when this coroutine gets destroyed, |
|
|
465 | but before it is joined. The callback gets passed the terminate arguments, |
|
|
466 | if any, and I<must not> die, under any circumstances. |
|
|
467 | |
|
|
468 | =cut |
|
|
469 | |
|
|
470 | sub on_destroy { |
|
|
471 | my ($self, $cb) = @_; |
|
|
472 | |
|
|
473 | push @{ $self->{_on_destroy} }, $cb; |
|
|
474 | } |
|
|
475 | |
|
|
476 | =item $oldprio = $coroutine->prio ($newprio) |
|
|
477 | |
|
|
478 | Sets (or gets, if the argument is missing) the priority of the |
|
|
479 | coroutine. Higher priority coroutines get run before lower priority |
|
|
480 | coroutines. Priorities are small signed integers (currently -4 .. +3), |
|
|
481 | that you can refer to using PRIO_xxx constants (use the import tag :prio |
|
|
482 | to get then): |
|
|
483 | |
|
|
484 | PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN |
|
|
485 | 3 > 1 > 0 > -1 > -3 > -4 |
|
|
486 | |
|
|
487 | # set priority to HIGH |
|
|
488 | current->prio(PRIO_HIGH); |
|
|
489 | |
|
|
490 | The idle coroutine ($Coro::idle) always has a lower priority than any |
|
|
491 | existing coroutine. |
|
|
492 | |
|
|
493 | Changing the priority of the current coroutine will take effect immediately, |
|
|
494 | but changing the priority of coroutines in the ready queue (but not |
|
|
495 | running) will only take effect after the next schedule (of that |
|
|
496 | coroutine). This is a bug that will be fixed in some future version. |
|
|
497 | |
|
|
498 | =item $newprio = $coroutine->nice ($change) |
|
|
499 | |
|
|
500 | Similar to C<prio>, but subtract the given value from the priority (i.e. |
|
|
501 | higher values mean lower priority, just as in unix). |
|
|
502 | |
|
|
503 | =item $olddesc = $coroutine->desc ($newdesc) |
|
|
504 | |
|
|
505 | Sets (or gets in case the argument is missing) the description for this |
|
|
506 | coroutine. This is just a free-form string you can associate with a |
|
|
507 | coroutine. |
|
|
508 | |
|
|
509 | This method simply sets the C<< $coroutine->{desc} >> member to the given |
|
|
510 | string. You can modify this member directly if you wish. |
|
|
511 | |
|
|
512 | =cut |
|
|
513 | |
|
|
514 | sub desc { |
|
|
515 | my $old = $_[0]{desc}; |
|
|
516 | $_[0]{desc} = $_[1] if @_ > 1; |
|
|
517 | $old; |
|
|
518 | } |
|
|
519 | |
|
|
520 | sub transfer { |
|
|
521 | require Carp; |
|
|
522 | Carp::croak ("You must not call ->transfer on Coro objects. Use Coro::State objects or the ->schedule_to method. Caught"); |
|
|
523 | } |
|
|
524 | |
|
|
525 | =back |
|
|
526 | |
|
|
527 | =head1 GLOBAL FUNCTIONS |
|
|
528 | |
|
|
529 | =over 4 |
|
|
530 | |
|
|
531 | =item Coro::nready |
|
|
532 | |
|
|
533 | Returns the number of coroutines that are currently in the ready state, |
|
|
534 | i.e. that can be switched to by calling C<schedule> directory or |
|
|
535 | indirectly. The value C<0> means that the only runnable coroutine is the |
|
|
536 | currently running one, so C<cede> would have no effect, and C<schedule> |
|
|
537 | would cause a deadlock unless there is an idle handler that wakes up some |
|
|
538 | coroutines. |
|
|
539 | |
|
|
540 | =item my $guard = Coro::guard { ... } |
|
|
541 | |
|
|
542 | This function still exists, but is deprecated. Please use the |
|
|
543 | C<Guard::guard> function instead. |
|
|
544 | |
|
|
545 | =cut |
|
|
546 | |
|
|
547 | BEGIN { *guard = \&Guard::guard } |
|
|
548 | |
|
|
549 | =item unblock_sub { ... } |
|
|
550 | |
|
|
551 | This utility function takes a BLOCK or code reference and "unblocks" it, |
|
|
552 | returning a new coderef. Unblocking means that calling the new coderef |
|
|
553 | will return immediately without blocking, returning nothing, while the |
|
|
554 | original code ref will be called (with parameters) from within another |
|
|
555 | coroutine. |
|
|
556 | |
|
|
557 | The reason this function exists is that many event libraries (such as the |
|
|
558 | venerable L<Event|Event> module) are not coroutine-safe (a weaker form |
|
|
559 | of reentrancy). This means you must not block within event callbacks, |
|
|
560 | otherwise you might suffer from crashes or worse. The only event library |
|
|
561 | currently known that is safe to use without C<unblock_sub> is L<EV>. |
|
|
562 | |
|
|
563 | This function allows your callbacks to block by executing them in another |
|
|
564 | coroutine where it is safe to block. One example where blocking is handy |
|
|
565 | is when you use the L<Coro::AIO|Coro::AIO> functions to save results to |
|
|
566 | disk, for example. |
|
|
567 | |
|
|
568 | In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when |
|
|
569 | creating event callbacks that want to block. |
|
|
570 | |
|
|
571 | If your handler does not plan to block (e.g. simply sends a message to |
|
|
572 | another coroutine, or puts some other coroutine into the ready queue), |
|
|
573 | there is no reason to use C<unblock_sub>. |
|
|
574 | |
|
|
575 | Note that you also need to use C<unblock_sub> for any other callbacks that |
|
|
576 | are indirectly executed by any C-based event loop. For example, when you |
|
|
577 | use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it |
|
|
578 | provides callbacks that are the result of some event callback, then you |
|
|
579 | must not block either, or use C<unblock_sub>. |
|
|
580 | |
|
|
581 | =cut |
|
|
582 | |
|
|
583 | our @unblock_queue; |
|
|
584 | |
|
|
585 | # we create a special coro because we want to cede, |
|
|
586 | # to reduce pressure on the coro pool (because most callbacks |
|
|
587 | # return immediately and can be reused) and because we cannot cede |
|
|
588 | # inside an event callback. |
93 | our $idle = new Coro sub { |
589 | our $unblock_scheduler = new Coro sub { |
94 | print STDERR "FATAL: deadlock detected\n"; |
590 | while () { |
95 | exit(51); |
591 | while (my $cb = pop @unblock_queue) { |
|
|
592 | &async_pool (@$cb); |
|
|
593 | |
|
|
594 | # for short-lived callbacks, this reduces pressure on the coro pool |
|
|
595 | # as the chance is very high that the async_poll coro will be back |
|
|
596 | # in the idle state when cede returns |
|
|
597 | cede; |
|
|
598 | } |
|
|
599 | schedule; # sleep well |
|
|
600 | } |
96 | }; |
601 | }; |
|
|
602 | $unblock_scheduler->{desc} = "[unblock_sub scheduler]"; |
97 | |
603 | |
98 | # we really need priorities... |
604 | sub unblock_sub(&) { |
99 | my @ready = (); # the ready queue. hehe, rather broken ;) |
605 | my $cb = shift; |
100 | |
606 | |
101 | # static methods. not really. |
607 | sub { |
|
|
608 | unshift @unblock_queue, [$cb, @_]; |
|
|
609 | $unblock_scheduler->ready; |
|
|
610 | } |
|
|
611 | } |
102 | |
612 | |
103 | =head2 STATIC METHODS |
613 | =item $cb = Coro::rouse_cb |
104 | |
614 | |
105 | Static methods are actually functions that operate on the current process only. |
615 | Create and return a "rouse callback". That's a code reference that, |
|
|
616 | when called, will remember a copy of its arguments and notify the owner |
|
|
617 | coroutine of the callback. |
|
|
618 | |
|
|
619 | See the next function. |
|
|
620 | |
|
|
621 | =item @args = Coro::rouse_wait [$cb] |
|
|
622 | |
|
|
623 | Wait for the specified rouse callback (or the last one that was created in |
|
|
624 | this coroutine). |
|
|
625 | |
|
|
626 | As soon as the callback is invoked (or when the callback was invoked |
|
|
627 | before C<rouse_wait>), it will return the arguments originally passed to |
|
|
628 | the rouse callback. |
|
|
629 | |
|
|
630 | See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example. |
|
|
631 | |
|
|
632 | =back |
|
|
633 | |
|
|
634 | =cut |
|
|
635 | |
|
|
636 | 1; |
|
|
637 | |
|
|
638 | =head1 HOW TO WAIT FOR A CALLBACK |
|
|
639 | |
|
|
640 | It is very common for a coroutine to wait for some callback to be |
|
|
641 | called. This occurs naturally when you use coroutines in an otherwise |
|
|
642 | event-based program, or when you use event-based libraries. |
|
|
643 | |
|
|
644 | These typically register a callback for some event, and call that callback |
|
|
645 | when the event occured. In a coroutine, however, you typically want to |
|
|
646 | just wait for the event, simplyifying things. |
|
|
647 | |
|
|
648 | For example C<< AnyEvent->child >> registers a callback to be called when |
|
|
649 | a specific child has exited: |
|
|
650 | |
|
|
651 | my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... }); |
|
|
652 | |
|
|
653 | But from withina coroutine, you often just want to write this: |
|
|
654 | |
|
|
655 | my $status = wait_for_child $pid; |
|
|
656 | |
|
|
657 | Coro offers two functions specifically designed to make this easy, |
|
|
658 | C<Coro::rouse_cb> and C<Coro::rouse_wait>. |
|
|
659 | |
|
|
660 | The first function, C<rouse_cb>, generates and returns a callback that, |
|
|
661 | when invoked, will save its arguments and notify the coroutine that |
|
|
662 | created the callback. |
|
|
663 | |
|
|
664 | The second function, C<rouse_wait>, waits for the callback to be called |
|
|
665 | (by calling C<schedule> to go to sleep) and returns the arguments |
|
|
666 | originally passed to the callback. |
|
|
667 | |
|
|
668 | Using these functions, it becomes easy to write the C<wait_for_child> |
|
|
669 | function mentioned above: |
|
|
670 | |
|
|
671 | sub wait_for_child($) { |
|
|
672 | my ($pid) = @_; |
|
|
673 | |
|
|
674 | my $watcher = AnyEvent->child (pid => $pid, cb => Coro::rouse_cb); |
|
|
675 | |
|
|
676 | my ($rpid, $rstatus) = Coro::rouse_wait; |
|
|
677 | $rstatus |
|
|
678 | } |
|
|
679 | |
|
|
680 | In the case where C<rouse_cb> and C<rouse_wait> are not flexible enough, |
|
|
681 | you can roll your own, using C<schedule>: |
|
|
682 | |
|
|
683 | sub wait_for_child($) { |
|
|
684 | my ($pid) = @_; |
|
|
685 | |
|
|
686 | # store the current coroutine in $current, |
|
|
687 | # and provide result variables for the closure passed to ->child |
|
|
688 | my $current = $Coro::current; |
|
|
689 | my ($done, $rstatus); |
|
|
690 | |
|
|
691 | # pass a closure to ->child |
|
|
692 | my $watcher = AnyEvent->child (pid => $pid, cb => sub { |
|
|
693 | $rstatus = $_[1]; # remember rstatus |
|
|
694 | $done = 1; # mark $rstatus as valud |
|
|
695 | }); |
|
|
696 | |
|
|
697 | # wait until the closure has been called |
|
|
698 | schedule while !$done; |
|
|
699 | |
|
|
700 | $rstatus |
|
|
701 | } |
|
|
702 | |
|
|
703 | |
|
|
704 | =head1 BUGS/LIMITATIONS |
106 | |
705 | |
107 | =over 4 |
706 | =over 4 |
108 | |
707 | |
109 | =item async { ... }; |
708 | =item fork with pthread backend |
110 | |
709 | |
111 | Create a new asynchronous process and return it's process object |
710 | When Coro is compiled using the pthread backend (which isn't recommended |
112 | (usually unused). When the sub returns the new process is automatically |
711 | but required on many BSDs as their libcs are completely broken), then |
113 | terminated. |
712 | coroutines will not survive a fork. There is no known workaround except to |
|
|
713 | fix your libc and use a saner backend. |
114 | |
714 | |
115 | =cut |
715 | =item perl process emulation ("threads") |
116 | |
716 | |
117 | sub async(&) { |
717 | This module is not perl-pseudo-thread-safe. You should only ever use this |
118 | (new Coro $_[0])->ready; |
718 | module from the first thread (this requirement might be removed in the |
119 | } |
719 | future to allow per-thread schedulers, but Coro::State does not yet allow |
|
|
720 | this). I recommend disabling thread support and using processes, as having |
|
|
721 | the windows process emulation enabled under unix roughly halves perl |
|
|
722 | performance, even when not used. |
120 | |
723 | |
121 | =item schedule |
724 | =item coroutine switching not signal safe |
122 | |
725 | |
123 | Calls the scheduler. Please note that the current process will not be put |
726 | You must not switch to another coroutine from within a signal handler |
124 | into the ready queue, so calling this function usually means you will |
727 | (only relevant with %SIG - most event libraries provide safe signals). |
125 | never be called again. |
|
|
126 | |
728 | |
127 | =cut |
729 | That means you I<MUST NOT> call any function that might "block" the |
128 | |
730 | current coroutine - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or |
129 | my $prev; |
731 | anything that calls those. Everything else, including calling C<ready>, |
130 | |
732 | works. |
131 | sub schedule { |
|
|
132 | # should be done using priorities :( |
|
|
133 | ($prev, $current) = ($current, shift @ready || $idle); |
|
|
134 | Coro::State::transfer($prev, $current); |
|
|
135 | } |
|
|
136 | |
|
|
137 | =item yield |
|
|
138 | |
|
|
139 | Yield to other processes. This function puts the current process into the |
|
|
140 | ready queue and calls C<schedule>. |
|
|
141 | |
|
|
142 | =cut |
|
|
143 | |
|
|
144 | sub yield { |
|
|
145 | $current->ready; |
|
|
146 | &schedule; |
|
|
147 | } |
|
|
148 | |
|
|
149 | =item terminate |
|
|
150 | |
|
|
151 | Terminates the current process. |
|
|
152 | |
|
|
153 | =cut |
|
|
154 | |
|
|
155 | sub terminate { |
|
|
156 | &schedule; |
|
|
157 | } |
|
|
158 | |
733 | |
159 | =back |
734 | =back |
160 | |
735 | |
161 | # dynamic methods |
|
|
162 | |
|
|
163 | =head2 PROCESS METHODS |
|
|
164 | |
|
|
165 | These are the methods you can call on process objects. |
|
|
166 | |
|
|
167 | =over 4 |
|
|
168 | |
|
|
169 | =item new Coro \⊂ |
|
|
170 | |
|
|
171 | Create a new process and return it. When the sub returns the process |
|
|
172 | automatically terminates. To start the process you must first put it into |
|
|
173 | the ready queue by calling the ready method. |
|
|
174 | |
|
|
175 | =cut |
|
|
176 | |
|
|
177 | sub new { |
|
|
178 | my $class = shift; |
|
|
179 | my $proc = $_[0]; |
|
|
180 | bless { |
|
|
181 | _coro_state => new Coro::State ($proc ? sub { &$proc; &terminate } : $proc), |
|
|
182 | }, $class; |
|
|
183 | } |
|
|
184 | |
|
|
185 | =item $process->ready |
|
|
186 | |
|
|
187 | Put the current process into the ready queue. |
|
|
188 | |
|
|
189 | =cut |
|
|
190 | |
|
|
191 | sub ready { |
|
|
192 | push @ready, $_[0]; |
|
|
193 | } |
|
|
194 | |
|
|
195 | =back |
|
|
196 | |
|
|
197 | =cut |
|
|
198 | |
|
|
199 | 1; |
|
|
200 | |
736 | |
201 | =head1 SEE ALSO |
737 | =head1 SEE ALSO |
202 | |
738 | |
203 | L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>, |
739 | Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>. |
204 | L<Coro::Signal>, L<Coro::State>. |
740 | |
|
|
741 | Debugging: L<Coro::Debug>. |
|
|
742 | |
|
|
743 | Support/Utility: L<Coro::Specific>, L<Coro::Util>. |
|
|
744 | |
|
|
745 | Locking and IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, |
|
|
746 | L<Coro::SemaphoreSet>, L<Coro::RWLock>. |
|
|
747 | |
|
|
748 | I/O and Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>. |
|
|
749 | |
|
|
750 | Compatibility with other modules: L<Coro::LWP> (but see also L<AnyEvent::HTTP> for |
|
|
751 | a better-working alternative), L<Coro::BDB>, L<Coro::Storable>, |
|
|
752 | L<Coro::Select>. |
|
|
753 | |
|
|
754 | XS API: L<Coro::MakeMaker>. |
|
|
755 | |
|
|
756 | Low level Configuration, Thread Environment, Continuations: L<Coro::State>. |
205 | |
757 | |
206 | =head1 AUTHOR |
758 | =head1 AUTHOR |
207 | |
759 | |
208 | Marc Lehmann <pcg@goof.com> |
760 | Marc Lehmann <schmorp@schmorp.de> |
209 | http://www.goof.com/pcg/marc/ |
761 | http://home.schmorp.de/ |
210 | |
762 | |
211 | =cut |
763 | =cut |
212 | |
764 | |