… | |
… | |
2 | |
2 | |
3 | Coro - coroutine process abstraction |
3 | Coro - coroutine process abstraction |
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 | This module collection manages coroutines. Coroutines are similar to |
|
|
32 | threads but don't (in general) run in parallel at the same time even |
|
|
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 | |
|
|
39 | Unlike a normal perl program, however, coroutines allow you to have |
|
|
40 | multiple running interpreters that share data, which is especially useful |
|
|
41 | to code pseudo-parallel processes and for event-based programming, such as |
|
|
42 | multiple HTTP-GET requests running concurrently. See L<Coro::AnyEvent> to |
|
|
43 | learn more. |
|
|
44 | |
|
|
45 | Coroutines are also useful because Perl has no support for threads (the so |
|
|
46 | called "threads" that perl offers are nothing more than the (bad) process |
|
|
47 | emulation coming from the Windows platform: On standard operating systems |
|
|
48 | they serve no purpose whatsoever, except by making your programs slow and |
|
|
49 | making them use a lot of memory. Best disable them when building perl, or |
|
|
50 | aks your software vendor/distributor to do it for you). |
|
|
51 | |
|
|
52 | In this module, coroutines are defined as "callchain + lexical variables + |
|
|
53 | @_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain, |
|
|
54 | its own set of lexicals and its own set of perls most important global |
|
|
55 | variables (see L<Coro::State> for more configuration). |
|
|
56 | |
23 | =cut |
57 | =cut |
24 | |
58 | |
25 | package Coro; |
59 | package Coro; |
26 | |
60 | |
|
|
61 | use strict qw(vars subs); |
|
|
62 | no warnings "uninitialized"; |
|
|
63 | |
27 | use Coro::State; |
64 | use Coro::State; |
28 | |
65 | |
29 | use base Exporter; |
66 | use base qw(Coro::State Exporter); |
30 | |
67 | |
|
|
68 | our $idle; # idle handler |
|
|
69 | our $main; # main coroutine |
|
|
70 | our $current; # current coroutine |
|
|
71 | |
31 | $VERSION = 0.04; |
72 | our $VERSION = 5.0; |
32 | |
73 | |
33 | @EXPORT = qw(async yield schedule); |
74 | our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); |
34 | @EXPORT_OK = qw($current); |
75 | our %EXPORT_TAGS = ( |
|
|
76 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
|
|
77 | ); |
|
|
78 | our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready)); |
35 | |
79 | |
36 | { |
80 | =over 4 |
37 | use subs 'async'; |
|
|
38 | |
81 | |
39 | my @async; |
82 | =item $Coro::main |
40 | |
83 | |
41 | # this way of handling attributes simply is NOT scalable ;() |
84 | This variable stores the coroutine object that represents the main |
42 | sub import { |
85 | program. While you cna C<ready> it and do most other things you can do to |
43 | Coro->export_to_level(1, @_); |
86 | coroutines, it is mainly useful to compare again C<$Coro::current>, to see |
44 | my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE}; |
87 | whether you are running in the main program or not. |
45 | *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub { |
88 | |
46 | my ($package, $ref) = (shift, shift); |
89 | =cut |
47 | my @attrs; |
90 | |
48 | for (@_) { |
91 | # $main is now being initialised by Coro::State |
49 | if ($_ eq "Coro") { |
92 | |
50 | push @async, $ref; |
93 | =item $Coro::current |
51 | } else { |
94 | |
52 | push @attrs, @_; |
95 | The coroutine object representing the current coroutine (the last |
|
|
96 | coroutine that the Coro scheduler switched to). The initial value is |
|
|
97 | C<$Coro::main> (of course). |
|
|
98 | |
|
|
99 | This variable is B<strictly> I<read-only>. You can take copies of the |
|
|
100 | value stored in it and use it as any other coroutine object, but you must |
|
|
101 | not otherwise modify the variable itself. |
|
|
102 | |
|
|
103 | =cut |
|
|
104 | |
|
|
105 | sub current() { $current } # [DEPRECATED] |
|
|
106 | |
|
|
107 | =item $Coro::idle |
|
|
108 | |
|
|
109 | 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 |
|
|
111 | pretty low-level functionality. |
|
|
112 | |
|
|
113 | This variable stores a callback that is called whenever the scheduler |
|
|
114 | finds no ready coroutines to run. The default implementation prints |
|
|
115 | "FATAL: deadlock detected" and exits, because the program has no other way |
|
|
116 | to continue. |
|
|
117 | |
|
|
118 | This hook is overwritten by modules such as C<Coro::Timer> and |
|
|
119 | C<Coro::AnyEvent> to wait on an external event that hopefully wake up a |
|
|
120 | coroutine so the scheduler can run it. |
|
|
121 | |
|
|
122 | Note that the callback I<must not>, under any circumstances, block |
|
|
123 | the current coroutine. Normally, this is achieved by having an "idle |
|
|
124 | coroutine" that calls the event loop and then blocks again, and then |
|
|
125 | readying that coroutine in the idle handler. |
|
|
126 | |
|
|
127 | See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this |
|
|
128 | technique. |
|
|
129 | |
|
|
130 | Please note that if your callback recursively invokes perl (e.g. for event |
|
|
131 | handlers), then it must be prepared to be called recursively itself. |
|
|
132 | |
|
|
133 | =cut |
|
|
134 | |
|
|
135 | $idle = sub { |
|
|
136 | require Carp; |
|
|
137 | Carp::croak ("FATAL: deadlock detected"); |
|
|
138 | }; |
|
|
139 | |
|
|
140 | sub _cancel { |
|
|
141 | my ($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 |
|
|
153 | # cannot destroy itself. |
|
|
154 | my @destroy; |
|
|
155 | my $manager; |
|
|
156 | |
|
|
157 | $manager = new Coro sub { |
|
|
158 | while () { |
|
|
159 | (shift @destroy)->_cancel |
|
|
160 | while @destroy; |
|
|
161 | |
|
|
162 | &schedule; |
|
|
163 | } |
|
|
164 | }; |
|
|
165 | $manager->{desc} = "[coro manager]"; |
|
|
166 | $manager->prio (PRIO_MAX); |
|
|
167 | |
|
|
168 | =back |
|
|
169 | |
|
|
170 | =head2 SIMPLE COROUTINE CREATION |
|
|
171 | |
|
|
172 | =over 4 |
|
|
173 | |
|
|
174 | =item async { ... } [@args...] |
|
|
175 | |
|
|
176 | Create a new coroutine and return it's coroutine object (usually |
|
|
177 | unused). The coroutine will be put into the ready queue, so |
|
|
178 | it will start running automatically on the next scheduler run. |
|
|
179 | |
|
|
180 | The first argument is a codeblock/closure that should be executed in the |
|
|
181 | coroutine. When it returns argument returns the coroutine is automatically |
|
|
182 | terminated. |
|
|
183 | |
|
|
184 | The remaining arguments are passed as arguments to the closure. |
|
|
185 | |
|
|
186 | See the C<Coro::State::new> constructor for info about the coroutine |
|
|
187 | environment in which coroutines are executed. |
|
|
188 | |
|
|
189 | Calling C<exit> in a coroutine will do the same as calling exit outside |
|
|
190 | the coroutine. Likewise, when the coroutine dies, the program will exit, |
|
|
191 | just as it would in the main program. |
|
|
192 | |
|
|
193 | If you do not want that, you can provide a default C<die> handler, or |
|
|
194 | simply avoid dieing (by use of C<eval>). |
|
|
195 | |
|
|
196 | Example: Create a new coroutine that just prints its arguments. |
|
|
197 | |
|
|
198 | async { |
|
|
199 | print "@_\n"; |
|
|
200 | } 1,2,3,4; |
|
|
201 | |
|
|
202 | =cut |
|
|
203 | |
|
|
204 | sub async(&@) { |
|
|
205 | my $coro = new Coro @_; |
|
|
206 | $coro->ready; |
|
|
207 | $coro |
|
|
208 | } |
|
|
209 | |
|
|
210 | =item async_pool { ... } [@args...] |
|
|
211 | |
|
|
212 | Similar to C<async>, but uses a coroutine pool, so you should not call |
|
|
213 | terminate or join on it (although you are allowed to), and you get a |
|
|
214 | coroutine that might have executed other code already (which can be good |
|
|
215 | or bad :). |
|
|
216 | |
|
|
217 | On the plus side, this function is faster than creating (and destroying) |
|
|
218 | a completly new coroutine, so if you need a lot of generic coroutines in |
|
|
219 | quick successsion, use C<async_pool>, not C<async>. |
|
|
220 | |
|
|
221 | The code block is executed in an C<eval> context and a warning will be |
|
|
222 | issued in case of an exception instead of terminating the program, as |
|
|
223 | C<async> does. As the coroutine is being reused, stuff like C<on_destroy> |
|
|
224 | will not work in the expected way, unless you call terminate or cancel, |
|
|
225 | which somehow defeats the purpose of pooling (but is fine in the |
|
|
226 | exceptional case). |
|
|
227 | |
|
|
228 | The priority will be reset to C<0> after each run, tracing will be |
|
|
229 | disabled, the description will be reset and the default output filehandle |
|
|
230 | gets restored, so you can change all these. Otherwise the coroutine will |
|
|
231 | be re-used "as-is": most notably if you change other per-coroutine global |
|
|
232 | stuff such as C<$/> you I<must needs> revert that change, which is most |
|
|
233 | simply done by using local as in: C<< local $/ >>. |
|
|
234 | |
|
|
235 | The idle pool size is limited to C<8> idle coroutines (this can be |
|
|
236 | adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle |
|
|
237 | coros as required. |
|
|
238 | |
|
|
239 | 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 |
|
|
241 | { 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 |
|
|
243 | (adjustable via $Coro::POOL_RSS) it will also be destroyed. |
|
|
244 | |
|
|
245 | =cut |
|
|
246 | |
|
|
247 | our $POOL_SIZE = 8; |
|
|
248 | our $POOL_RSS = 16 * 1024; |
|
|
249 | our @async_pool; |
|
|
250 | |
|
|
251 | sub pool_handler { |
|
|
252 | my $cb; |
|
|
253 | |
|
|
254 | while () { |
|
|
255 | eval { |
|
|
256 | while () { |
|
|
257 | _pool_1 $cb; |
53 | } |
258 | &$cb; |
|
|
259 | _pool_2 $cb; |
|
|
260 | &schedule; |
54 | } |
261 | } |
55 | return $old ? $old->($package, $name, @attrs) : @attrs; |
|
|
56 | }; |
262 | }; |
57 | } |
|
|
58 | |
263 | |
59 | sub INIT { |
264 | if ($@) { |
60 | async pop @async while @async; |
265 | last if $@ eq "\3async_pool terminate\2\n"; |
|
|
266 | warn $@; |
|
|
267 | } |
61 | } |
268 | } |
62 | } |
269 | } |
63 | |
270 | |
64 | =item $main |
271 | sub async_pool(&@) { |
|
|
272 | # this is also inlined into the unblock_scheduler |
|
|
273 | my $coro = (pop @async_pool) || new Coro \&pool_handler; |
65 | |
274 | |
66 | This coroutine represents the main program. |
275 | $coro->{_invoke} = [@_]; |
|
|
276 | $coro->ready; |
67 | |
277 | |
68 | =cut |
278 | $coro |
69 | |
|
|
70 | our $main = new Coro; |
|
|
71 | |
|
|
72 | =item $current |
|
|
73 | |
|
|
74 | The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course). |
|
|
75 | |
|
|
76 | =cut |
|
|
77 | |
|
|
78 | # maybe some other module used Coro::Specific before... |
|
|
79 | if ($current) { |
|
|
80 | $main->{specific} = $current->{specific}; |
|
|
81 | } |
279 | } |
82 | |
280 | |
83 | our $current = $main; |
281 | =back |
84 | |
|
|
85 | =item $idle |
|
|
86 | |
|
|
87 | The coroutine to switch to when no other coroutine is running. The default |
|
|
88 | implementation prints "FATAL: deadlock detected" and exits. |
|
|
89 | |
|
|
90 | =cut |
|
|
91 | |
|
|
92 | # should be done using priorities :( |
|
|
93 | our $idle = new Coro sub { |
|
|
94 | print STDERR "FATAL: deadlock detected\n"; |
|
|
95 | exit(51); |
|
|
96 | }; |
|
|
97 | |
|
|
98 | # we really need priorities... |
|
|
99 | my @ready = (); # the ready queue. hehe, rather broken ;) |
|
|
100 | |
|
|
101 | # static methods. not really. |
|
|
102 | |
282 | |
103 | =head2 STATIC METHODS |
283 | =head2 STATIC METHODS |
104 | |
284 | |
105 | Static methods are actually functions that operate on the current process only. |
285 | Static methods are actually functions that operate on the current coroutine. |
106 | |
286 | |
107 | =over 4 |
287 | =over 4 |
108 | |
288 | |
109 | =item async { ... }; |
|
|
110 | |
|
|
111 | Create a new asynchronous process and return it's process object |
|
|
112 | (usually unused). When the sub returns the new process is automatically |
|
|
113 | terminated. |
|
|
114 | |
|
|
115 | =cut |
|
|
116 | |
|
|
117 | sub async(&) { |
|
|
118 | my $pid = new Coro $_[0]; |
|
|
119 | $pid->ready; |
|
|
120 | $pid; |
|
|
121 | } |
|
|
122 | |
|
|
123 | =item schedule |
289 | =item schedule |
124 | |
290 | |
125 | Calls the scheduler. Please note that the current process will not be put |
291 | Calls the scheduler. The scheduler will find the next coroutine that is |
|
|
292 | to be run from the ready queue and switches to it. The next coroutine |
|
|
293 | to be run is simply the one with the highest priority that is longest |
|
|
294 | in its ready queue. If there is no coroutine ready, it will clal the |
|
|
295 | C<$Coro::idle> hook. |
|
|
296 | |
|
|
297 | Please note that the current coroutine will I<not> be put into the ready |
126 | into the ready queue, so calling this function usually means you will |
298 | queue, so calling this function usually means you will never be called |
127 | never be called again. |
299 | again unless something else (e.g. an event handler) calls C<< ->ready >>, |
|
|
300 | thus waking you up. |
128 | |
301 | |
129 | =cut |
302 | This makes C<schedule> I<the> generic method to use to block the current |
|
|
303 | coroutine and wait for events: first you remember the current coroutine in |
|
|
304 | a variable, then arrange for some callback of yours to call C<< ->ready |
|
|
305 | >> 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, |
|
|
307 | so you need to check whether the event indeed happened, e.g. by storing the |
|
|
308 | status in a variable. |
130 | |
309 | |
131 | my $prev; |
310 | The canonical way to wait on external events is this: |
132 | |
311 | |
133 | sub schedule { |
312 | { |
134 | # should be done using priorities :( |
313 | # remember current coroutine |
135 | ($prev, $current) = ($current, shift @ready || $idle); |
314 | my $current = $Coro::current; |
136 | Coro::State::transfer($prev, $current); |
|
|
137 | } |
|
|
138 | |
315 | |
139 | =item yield |
316 | # register a hypothetical event handler |
140 | |
317 | on_event_invoke sub { |
141 | Yield to other processes. This function puts the current process into the |
318 | # wake up sleeping coroutine |
142 | ready queue and calls C<schedule>. |
|
|
143 | |
|
|
144 | =cut |
|
|
145 | |
|
|
146 | sub yield { |
|
|
147 | $current->ready; |
319 | $current->ready; |
148 | &schedule; |
320 | undef $current; |
149 | } |
321 | }; |
150 | |
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 | |
|
|
329 | =item cede |
|
|
330 | |
|
|
331 | "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 |
|
|
333 | up the current "timeslice" to other coroutines of the same or higher |
|
|
334 | priority. Once your coroutine gets its turn again it will automatically be |
|
|
335 | resumed. |
|
|
336 | |
|
|
337 | This function is often called C<yield> in other languages. |
|
|
338 | |
|
|
339 | =item Coro::cede_notself |
|
|
340 | |
|
|
341 | Works like cede, but is not exported by default and will cede to I<any> |
|
|
342 | coroutine, regardless of priority. This is useful sometimes to ensure |
|
|
343 | progress is made. |
|
|
344 | |
151 | =item terminate |
345 | =item terminate [arg...] |
152 | |
346 | |
153 | Terminates the current process. |
347 | Terminates the current coroutine with the given status values (see L<cancel>). |
|
|
348 | |
|
|
349 | =item killall |
|
|
350 | |
|
|
351 | 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 |
|
|
353 | usually only one of them should inherit the running coroutines. |
|
|
354 | |
|
|
355 | 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 |
|
|
357 | program calls this function, there will be some one-time resource leak. |
154 | |
358 | |
155 | =cut |
359 | =cut |
156 | |
360 | |
157 | sub terminate { |
361 | sub terminate { |
158 | &schedule; |
362 | $current->cancel (@_); |
|
|
363 | } |
|
|
364 | |
|
|
365 | sub killall { |
|
|
366 | for (Coro::State::list) { |
|
|
367 | $_->cancel |
|
|
368 | if $_ != $current && UNIVERSAL::isa $_, "Coro"; |
|
|
369 | } |
159 | } |
370 | } |
160 | |
371 | |
161 | =back |
372 | =back |
162 | |
373 | |
163 | # dynamic methods |
|
|
164 | |
|
|
165 | =head2 PROCESS METHODS |
374 | =head2 COROUTINE METHODS |
166 | |
375 | |
167 | These are the methods you can call on process objects. |
376 | These are the methods you can call on coroutine objects (or to create |
|
|
377 | them). |
168 | |
378 | |
169 | =over 4 |
379 | =over 4 |
170 | |
380 | |
171 | =item new Coro \⊂ |
381 | =item new Coro \&sub [, @args...] |
172 | |
382 | |
173 | Create a new process and return it. When the sub returns the process |
383 | Create a new coroutine and return it. When the sub returns, the coroutine |
174 | automatically terminates. To start the process you must first put it into |
384 | automatically terminates as if C<terminate> with the returned values were |
|
|
385 | called. To make the coroutine run you must first put it into the ready |
175 | the ready queue by calling the ready method. |
386 | queue by calling the ready method. |
176 | |
387 | |
|
|
388 | See C<async> and C<Coro::State::new> for additional info about the |
|
|
389 | coroutine environment. |
|
|
390 | |
177 | =cut |
391 | =cut |
|
|
392 | |
|
|
393 | sub _run_coro { |
|
|
394 | terminate &{+shift}; |
|
|
395 | } |
178 | |
396 | |
179 | sub new { |
397 | sub new { |
180 | my $class = shift; |
398 | my $class = shift; |
|
|
399 | |
|
|
400 | $class->SUPER::new (\&_run_coro, @_) |
|
|
401 | } |
|
|
402 | |
|
|
403 | =item $success = $coroutine->ready |
|
|
404 | |
|
|
405 | Put the given coroutine into the end of its ready queue (there is one |
|
|
406 | queue for each priority) and return true. If the coroutine is already in |
|
|
407 | the ready queue, do nothing and return false. |
|
|
408 | |
|
|
409 | This ensures that the scheduler will resume this coroutine automatically |
|
|
410 | once all the coroutines of higher priority and all coroutines of the same |
|
|
411 | priority that were put into the ready queue earlier have been resumed. |
|
|
412 | |
|
|
413 | =item $is_ready = $coroutine->is_ready |
|
|
414 | |
|
|
415 | Return whether the coroutine is currently the ready queue or not, |
|
|
416 | |
|
|
417 | =item $coroutine->cancel (arg...) |
|
|
418 | |
|
|
419 | Terminates the given coroutine and makes it return the given arguments as |
|
|
420 | status (default: the empty list). Never returns if the coroutine is the |
|
|
421 | current coroutine. |
|
|
422 | |
|
|
423 | =cut |
|
|
424 | |
|
|
425 | sub cancel { |
|
|
426 | my $self = shift; |
|
|
427 | $self->{_status} = [@_]; |
|
|
428 | |
|
|
429 | if ($current == $self) { |
|
|
430 | push @destroy, $self; |
|
|
431 | $manager->ready; |
|
|
432 | &schedule while 1; |
|
|
433 | } else { |
|
|
434 | $self->_cancel; |
|
|
435 | } |
|
|
436 | } |
|
|
437 | |
|
|
438 | =item $coroutine->throw ([$scalar]) |
|
|
439 | |
|
|
440 | If C<$throw> is specified and defined, it will be thrown as an exception |
|
|
441 | inside the coroutine at the next convenient point in time. Otherwise |
|
|
442 | clears the exception object. |
|
|
443 | |
|
|
444 | Coro will check for the exception each time a schedule-like-function |
|
|
445 | returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down |
|
|
446 | >>, C<< Coro::Handle->readable >> and so on. Most of these functions |
|
|
447 | detect this case and return early in case an exception is pending. |
|
|
448 | |
|
|
449 | The exception object will be thrown "as is" with the specified scalar in |
|
|
450 | C<$@>, i.e. if it is a string, no line number or newline will be appended |
|
|
451 | (unlike with C<die>). |
|
|
452 | |
|
|
453 | This can be used as a softer means than C<cancel> to ask a coroutine to |
|
|
454 | end itself, although there is no guarantee that the exception will lead to |
|
|
455 | termination, and if the exception isn't caught it might well end the whole |
|
|
456 | program. |
|
|
457 | |
|
|
458 | You might also think of C<throw> as being the moral equivalent of |
|
|
459 | C<kill>ing a coroutine with a signal (in this case, a scalar). |
|
|
460 | |
|
|
461 | =item $coroutine->join |
|
|
462 | |
|
|
463 | Wait until the coroutine terminates and return any values given to the |
|
|
464 | C<terminate> or C<cancel> functions. C<join> can be called concurrently |
|
|
465 | from multiple coroutines, and all will be resumed and given the status |
|
|
466 | return once the C<$coroutine> terminates. |
|
|
467 | |
|
|
468 | =cut |
|
|
469 | |
|
|
470 | sub join { |
|
|
471 | my $self = shift; |
|
|
472 | |
|
|
473 | unless ($self->{_status}) { |
|
|
474 | my $current = $current; |
|
|
475 | |
|
|
476 | push @{$self->{_on_destroy}}, sub { |
|
|
477 | $current->ready; |
|
|
478 | undef $current; |
|
|
479 | }; |
|
|
480 | |
|
|
481 | &schedule while $current; |
|
|
482 | } |
|
|
483 | |
|
|
484 | wantarray ? @{$self->{_status}} : $self->{_status}[0]; |
|
|
485 | } |
|
|
486 | |
|
|
487 | =item $coroutine->on_destroy (\&cb) |
|
|
488 | |
|
|
489 | Registers a callback that is called when this coroutine gets destroyed, |
|
|
490 | but before it is joined. The callback gets passed the terminate arguments, |
|
|
491 | if any, and I<must not> die, under any circumstances. |
|
|
492 | |
|
|
493 | =cut |
|
|
494 | |
|
|
495 | sub on_destroy { |
|
|
496 | my ($self, $cb) = @_; |
|
|
497 | |
|
|
498 | push @{ $self->{_on_destroy} }, $cb; |
|
|
499 | } |
|
|
500 | |
|
|
501 | =item $oldprio = $coroutine->prio ($newprio) |
|
|
502 | |
|
|
503 | Sets (or gets, if the argument is missing) the priority of the |
|
|
504 | coroutine. Higher priority coroutines get run before lower priority |
|
|
505 | coroutines. Priorities are small signed integers (currently -4 .. +3), |
|
|
506 | that you can refer to using PRIO_xxx constants (use the import tag :prio |
|
|
507 | to get then): |
|
|
508 | |
|
|
509 | PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN |
|
|
510 | 3 > 1 > 0 > -1 > -3 > -4 |
|
|
511 | |
|
|
512 | # set priority to HIGH |
|
|
513 | current->prio(PRIO_HIGH); |
|
|
514 | |
|
|
515 | The idle coroutine ($Coro::idle) always has a lower priority than any |
|
|
516 | existing coroutine. |
|
|
517 | |
|
|
518 | Changing the priority of the current coroutine will take effect immediately, |
|
|
519 | but changing the priority of coroutines in the ready queue (but not |
|
|
520 | running) will only take effect after the next schedule (of that |
|
|
521 | coroutine). This is a bug that will be fixed in some future version. |
|
|
522 | |
|
|
523 | =item $newprio = $coroutine->nice ($change) |
|
|
524 | |
|
|
525 | Similar to C<prio>, but subtract the given value from the priority (i.e. |
|
|
526 | higher values mean lower priority, just as in unix). |
|
|
527 | |
|
|
528 | =item $olddesc = $coroutine->desc ($newdesc) |
|
|
529 | |
|
|
530 | Sets (or gets in case the argument is missing) the description for this |
|
|
531 | coroutine. This is just a free-form string you can associate with a |
|
|
532 | coroutine. |
|
|
533 | |
|
|
534 | This method simply sets the C<< $coroutine->{desc} >> member to the given |
|
|
535 | string. You can modify this member directly if you wish. |
|
|
536 | |
|
|
537 | =cut |
|
|
538 | |
|
|
539 | sub desc { |
181 | my $proc = $_[0]; |
540 | my $old = $_[0]{desc}; |
182 | bless { |
541 | $_[0]{desc} = $_[1] if @_ > 1; |
183 | _coro_state => new Coro::State ($proc ? sub { &$proc; &terminate } : $proc), |
542 | $old; |
184 | }, $class; |
|
|
185 | } |
|
|
186 | |
|
|
187 | =item $process->ready |
|
|
188 | |
|
|
189 | Put the current process into the ready queue. |
|
|
190 | |
|
|
191 | =cut |
|
|
192 | |
|
|
193 | sub ready { |
|
|
194 | push @ready, $_[0]; |
|
|
195 | } |
543 | } |
196 | |
544 | |
197 | =back |
545 | =back |
198 | |
546 | |
|
|
547 | =head2 GLOBAL FUNCTIONS |
|
|
548 | |
|
|
549 | =over 4 |
|
|
550 | |
|
|
551 | =item Coro::nready |
|
|
552 | |
|
|
553 | Returns the number of coroutines that are currently in the ready state, |
|
|
554 | i.e. that can be switched to by calling C<schedule> directory or |
|
|
555 | indirectly. The value C<0> means that the only runnable coroutine is the |
|
|
556 | currently running one, so C<cede> would have no effect, and C<schedule> |
|
|
557 | would cause a deadlock unless there is an idle handler that wakes up some |
|
|
558 | coroutines. |
|
|
559 | |
|
|
560 | =item my $guard = Coro::guard { ... } |
|
|
561 | |
|
|
562 | This creates and returns a guard object. Nothing happens until the object |
|
|
563 | gets destroyed, in which case the codeblock given as argument will be |
|
|
564 | executed. This is useful to free locks or other resources in case of a |
|
|
565 | runtime error or when the coroutine gets canceled, as in both cases the |
|
|
566 | guard block will be executed. The guard object supports only one method, |
|
|
567 | C<< ->cancel >>, which will keep the codeblock from being executed. |
|
|
568 | |
|
|
569 | Example: set some flag and clear it again when the coroutine gets canceled |
|
|
570 | or the function returns: |
|
|
571 | |
|
|
572 | sub do_something { |
|
|
573 | my $guard = Coro::guard { $busy = 0 }; |
|
|
574 | $busy = 1; |
|
|
575 | |
|
|
576 | # do something that requires $busy to be true |
|
|
577 | } |
|
|
578 | |
|
|
579 | =cut |
|
|
580 | |
|
|
581 | sub guard(&) { |
|
|
582 | bless \(my $cb = $_[0]), "Coro::guard" |
|
|
583 | } |
|
|
584 | |
|
|
585 | sub Coro::guard::cancel { |
|
|
586 | ${$_[0]} = sub { }; |
|
|
587 | } |
|
|
588 | |
|
|
589 | sub Coro::guard::DESTROY { |
|
|
590 | ${$_[0]}->(); |
|
|
591 | } |
|
|
592 | |
|
|
593 | |
|
|
594 | =item unblock_sub { ... } |
|
|
595 | |
|
|
596 | This utility function takes a BLOCK or code reference and "unblocks" it, |
|
|
597 | returning a new coderef. Unblocking means that calling the new coderef |
|
|
598 | will return immediately without blocking, returning nothing, while the |
|
|
599 | original code ref will be called (with parameters) from within another |
|
|
600 | coroutine. |
|
|
601 | |
|
|
602 | The reason this function exists is that many event libraries (such as the |
|
|
603 | venerable L<Event|Event> module) are not coroutine-safe (a weaker form |
|
|
604 | of thread-safety). This means you must not block within event callbacks, |
|
|
605 | otherwise you might suffer from crashes or worse. The only event library |
|
|
606 | currently known that is safe to use without C<unblock_sub> is L<EV>. |
|
|
607 | |
|
|
608 | This function allows your callbacks to block by executing them in another |
|
|
609 | coroutine where it is safe to block. One example where blocking is handy |
|
|
610 | is when you use the L<Coro::AIO|Coro::AIO> functions to save results to |
|
|
611 | disk, for example. |
|
|
612 | |
|
|
613 | In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when |
|
|
614 | creating event callbacks that want to block. |
|
|
615 | |
|
|
616 | If your handler does not plan to block (e.g. simply sends a message to |
|
|
617 | another coroutine, or puts some other coroutine into the ready queue), |
|
|
618 | there is no reason to use C<unblock_sub>. |
|
|
619 | |
|
|
620 | Note that you also need to use C<unblock_sub> for any other callbacks that |
|
|
621 | are indirectly executed by any C-based event loop. For example, when you |
|
|
622 | use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it |
|
|
623 | provides callbacks that are the result of some event callback, then you |
|
|
624 | must not block either, or use C<unblock_sub>. |
|
|
625 | |
|
|
626 | =cut |
|
|
627 | |
|
|
628 | our @unblock_queue; |
|
|
629 | |
|
|
630 | # we create a special coro because we want to cede, |
|
|
631 | # to reduce pressure on the coro pool (because most callbacks |
|
|
632 | # return immediately and can be reused) and because we cannot cede |
|
|
633 | # inside an event callback. |
|
|
634 | our $unblock_scheduler = new Coro sub { |
|
|
635 | while () { |
|
|
636 | while (my $cb = pop @unblock_queue) { |
|
|
637 | # this is an inlined copy of async_pool |
|
|
638 | my $coro = (pop @async_pool) || new Coro \&pool_handler; |
|
|
639 | |
|
|
640 | $coro->{_invoke} = $cb; |
|
|
641 | $coro->ready; |
|
|
642 | cede; # for short-lived callbacks, this reduces pressure on the coro pool |
|
|
643 | } |
|
|
644 | schedule; # sleep well |
|
|
645 | } |
|
|
646 | }; |
|
|
647 | $unblock_scheduler->{desc} = "[unblock_sub scheduler]"; |
|
|
648 | |
|
|
649 | sub unblock_sub(&) { |
|
|
650 | my $cb = shift; |
|
|
651 | |
|
|
652 | sub { |
|
|
653 | unshift @unblock_queue, [$cb, @_]; |
|
|
654 | $unblock_scheduler->ready; |
|
|
655 | } |
|
|
656 | } |
|
|
657 | |
|
|
658 | =back |
|
|
659 | |
199 | =cut |
660 | =cut |
200 | |
661 | |
201 | 1; |
662 | 1; |
202 | |
663 | |
|
|
664 | =head1 BUGS/LIMITATIONS |
|
|
665 | |
|
|
666 | =over 4 |
|
|
667 | |
|
|
668 | =item fork with pthread backend |
|
|
669 | |
|
|
670 | When Coro is compiled using the pthread backend (which isn't recommended |
|
|
671 | but required on many BSDs as their libcs are completely broken), then |
|
|
672 | coroutines will not survive a fork. There is no known workaround except to |
|
|
673 | fix your libc and use a saner backend. |
|
|
674 | |
|
|
675 | =item perl process emulation ("threads") |
|
|
676 | |
|
|
677 | This module is not perl-pseudo-thread-safe. You should only ever use this |
|
|
678 | module from the same thread (this requirement might be removed in the |
|
|
679 | future to allow per-thread schedulers, but Coro::State does not yet allow |
|
|
680 | this). I recommend disabling thread support and using processes, as having |
|
|
681 | the windows process emulation enabled under unix roughly halves perl |
|
|
682 | performance, even when not used. |
|
|
683 | |
|
|
684 | =item coroutine switching not signal safe |
|
|
685 | |
|
|
686 | You must not switch to another coroutine from within a signal handler |
|
|
687 | (only relevant with %SIG - most event libraries provide safe signals). |
|
|
688 | |
|
|
689 | That means you I<MUST NOT> call any function that might "block" the |
|
|
690 | current coroutine - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or |
|
|
691 | anything that calls those. Everything else, including calling C<ready>, |
|
|
692 | works. |
|
|
693 | |
|
|
694 | =back |
|
|
695 | |
|
|
696 | |
203 | =head1 SEE ALSO |
697 | =head1 SEE ALSO |
204 | |
698 | |
205 | L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>, |
699 | Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>. |
206 | L<Coro::Signal>, L<Coro::State>, L<Coro::Event>. |
700 | |
|
|
701 | Debugging: L<Coro::Debug>. |
|
|
702 | |
|
|
703 | Support/Utility: L<Coro::Specific>, L<Coro::Util>. |
|
|
704 | |
|
|
705 | Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>. |
|
|
706 | |
|
|
707 | IO/Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>. |
|
|
708 | |
|
|
709 | Compatibility: L<Coro::LWP>, L<Coro::BDB>, L<Coro::Storable>, L<Coro::Select>. |
|
|
710 | |
|
|
711 | XS API: L<Coro::MakeMaker>. |
|
|
712 | |
|
|
713 | Low level Configuration, Coroutine Environment: L<Coro::State>. |
207 | |
714 | |
208 | =head1 AUTHOR |
715 | =head1 AUTHOR |
209 | |
716 | |
210 | Marc Lehmann <pcg@goof.com> |
717 | Marc Lehmann <schmorp@schmorp.de> |
211 | http://www.goof.com/pcg/marc/ |
718 | http://home.schmorp.de/ |
212 | |
719 | |
213 | =cut |
720 | =cut |
214 | |
721 | |