… | |
… | |
8 | |
8 | |
9 | async { |
9 | async { |
10 | # some asynchronous thread of execution |
10 | # some asynchronous thread of execution |
11 | }; |
11 | }; |
12 | |
12 | |
13 | # alternatively create an async process like this: |
13 | # alternatively create an async coroutine like this: |
14 | |
14 | |
15 | sub some_func : Coro { |
15 | sub some_func : Coro { |
16 | # some more async code |
16 | # some more async code |
17 | } |
17 | } |
18 | |
18 | |
19 | cede; |
19 | cede; |
20 | |
20 | |
21 | =head1 DESCRIPTION |
21 | =head1 DESCRIPTION |
22 | |
22 | |
23 | This module collection manages coroutines. Coroutines are similar to |
23 | This module collection manages coroutines. Coroutines are similar |
24 | threads but don't run in parallel. |
24 | to threads but don't run in parallel at the same time even on SMP |
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25 | machines. The specific flavor of coroutine use din this module also |
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26 | guarentees you that it will not switch between coroutines unless |
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27 | necessary, at easily-identified points in your program, so locking and |
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28 | parallel access are rarely an issue, making coroutine programming much |
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29 | safer than threads programming. |
25 | |
30 | |
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31 | (Perl, however, does not natively support real threads but instead does a |
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32 | very slow and memory-intensive emulation of processes using threads. This |
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33 | is a performance win on Windows machines, and a loss everywhere else). |
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34 | |
26 | In this module, coroutines are defined as "callchain + lexical variables |
35 | In this module, coroutines are defined as "callchain + lexical variables + |
27 | + @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own |
36 | @_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain, |
28 | callchain, it's own set of lexicals and it's own set of perl's most |
37 | its own set of lexicals and its own set of perls most important global |
29 | important global variables. |
38 | variables. |
30 | |
39 | |
31 | =cut |
40 | =cut |
32 | |
41 | |
33 | package Coro; |
42 | package Coro; |
34 | |
43 | |
… | |
… | |
41 | |
50 | |
42 | our $idle; # idle handler |
51 | our $idle; # idle handler |
43 | our $main; # main coroutine |
52 | our $main; # main coroutine |
44 | our $current; # current coroutine |
53 | our $current; # current coroutine |
45 | |
54 | |
46 | our $VERSION = '2.5'; |
55 | our $VERSION = '3.2'; |
47 | |
56 | |
48 | our @EXPORT = qw(async cede schedule terminate current); |
57 | our @EXPORT = qw(async cede schedule terminate current unblock_sub); |
49 | our %EXPORT_TAGS = ( |
58 | our %EXPORT_TAGS = ( |
50 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
59 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
51 | ); |
60 | ); |
52 | our @EXPORT_OK = @{$EXPORT_TAGS{prio}}; |
61 | our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready)); |
53 | |
62 | |
54 | { |
63 | { |
55 | my @async; |
64 | my @async; |
56 | my $init; |
65 | my $init; |
57 | |
66 | |
58 | # this way of handling attributes simply is NOT scalable ;() |
67 | # this way of handling attributes simply is NOT scalable ;() |
59 | sub import { |
68 | sub import { |
60 | no strict 'refs'; |
69 | no strict 'refs'; |
61 | |
70 | |
62 | Coro->export_to_level(1, @_); |
71 | Coro->export_to_level (1, @_); |
63 | |
72 | |
64 | my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE}; |
73 | my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE}; |
65 | *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub { |
74 | *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub { |
66 | my ($package, $ref) = (shift, shift); |
75 | my ($package, $ref) = (shift, shift); |
67 | my @attrs; |
76 | my @attrs; |
… | |
… | |
105 | C<Coro::current> function instead. |
114 | C<Coro::current> function instead. |
106 | |
115 | |
107 | =cut |
116 | =cut |
108 | |
117 | |
109 | # maybe some other module used Coro::Specific before... |
118 | # maybe some other module used Coro::Specific before... |
110 | if ($current) { |
|
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111 | $main->{specific} = $current->{specific}; |
119 | $main->{specific} = $current->{specific} |
112 | } |
120 | if $current; |
113 | |
121 | |
114 | $current = $main; |
122 | _set_current $main; |
115 | |
123 | |
116 | sub current() { $current } |
124 | sub current() { $current } |
117 | |
125 | |
118 | =item $idle |
126 | =item $idle |
119 | |
127 | |
120 | A callback that is called whenever the scheduler finds no ready coroutines |
128 | A callback that is called whenever the scheduler finds no ready coroutines |
121 | to run. The default implementation prints "FATAL: deadlock detected" and |
129 | to run. The default implementation prints "FATAL: deadlock detected" and |
122 | exits. |
130 | exits, because the program has no other way to continue. |
123 | |
131 | |
124 | This hook is overwritten by modules such as C<Coro::Timer> and |
132 | This hook is overwritten by modules such as C<Coro::Timer> and |
125 | C<Coro::Event> to wait on an external event that hopefully wakes up some |
133 | C<Coro::Event> to wait on an external event that hopefully wake up a |
126 | coroutine. |
134 | coroutine so the scheduler can run it. |
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135 | |
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136 | Please note that if your callback recursively invokes perl (e.g. for event |
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137 | handlers), then it must be prepared to be called recursively. |
127 | |
138 | |
128 | =cut |
139 | =cut |
129 | |
140 | |
130 | $idle = sub { |
141 | $idle = sub { |
131 | print STDERR "FATAL: deadlock detected\n"; |
142 | require Carp; |
132 | exit (51); |
143 | Carp::croak ("FATAL: deadlock detected"); |
133 | }; |
144 | }; |
134 | |
145 | |
135 | # this coroutine is necessary because a coroutine |
146 | # this coroutine is necessary because a coroutine |
136 | # cannot destroy itself. |
147 | # cannot destroy itself. |
137 | my @destroy; |
148 | my @destroy; |
138 | my $manager; |
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139 | $manager = new Coro sub { |
149 | my $manager; $manager = new Coro sub { |
140 | while () { |
150 | while () { |
141 | # by overwriting the state object with the manager we destroy it |
151 | # by overwriting the state object with the manager we destroy it |
142 | # while still being able to schedule this coroutine (in case it has |
152 | # while still being able to schedule this coroutine (in case it has |
143 | # been readied multiple times. this is harmless since the manager |
153 | # been readied multiple times. this is harmless since the manager |
144 | # can be called as many times as neccessary and will always |
154 | # can be called as many times as neccessary and will always |
… | |
… | |
147 | my $coro = pop @destroy; |
157 | my $coro = pop @destroy; |
148 | $coro->{status} ||= []; |
158 | $coro->{status} ||= []; |
149 | $_->ready for @{delete $coro->{join} || []}; |
159 | $_->ready for @{delete $coro->{join} || []}; |
150 | |
160 | |
151 | # the next line destroys the coro state, but keeps the |
161 | # the next line destroys the coro state, but keeps the |
152 | # process itself intact (we basically make it a zombie |
162 | # coroutine itself intact (we basically make it a zombie |
153 | # process that always runs the manager thread, so it's possible |
163 | # coroutine that always runs the manager thread, so it's possible |
154 | # to transfer() to this process). |
164 | # to transfer() to this coroutine). |
155 | $coro->_clone_state_from ($manager); |
165 | $coro->_clone_state_from ($manager); |
156 | } |
166 | } |
157 | &schedule; |
167 | &schedule; |
158 | } |
168 | } |
159 | }; |
169 | }; |
… | |
… | |
162 | |
172 | |
163 | =back |
173 | =back |
164 | |
174 | |
165 | =head2 STATIC METHODS |
175 | =head2 STATIC METHODS |
166 | |
176 | |
167 | Static methods are actually functions that operate on the current process only. |
177 | Static methods are actually functions that operate on the current coroutine only. |
168 | |
178 | |
169 | =over 4 |
179 | =over 4 |
170 | |
180 | |
171 | =item async { ... } [@args...] |
181 | =item async { ... } [@args...] |
172 | |
182 | |
173 | Create a new asynchronous process and return it's process object |
183 | Create a new asynchronous coroutine and return it's coroutine object |
174 | (usually unused). When the sub returns the new process is automatically |
184 | (usually unused). When the sub returns the new coroutine is automatically |
175 | terminated. |
185 | terminated. |
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186 | |
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187 | Calling C<exit> in a coroutine will not work correctly, so do not do that. |
176 | |
188 | |
177 | When the coroutine dies, the program will exit, just as in the main |
189 | When the coroutine dies, the program will exit, just as in the main |
178 | program. |
190 | program. |
179 | |
191 | |
180 | # create a new coroutine that just prints its arguments |
192 | # create a new coroutine that just prints its arguments |
… | |
… | |
190 | $pid |
202 | $pid |
191 | } |
203 | } |
192 | |
204 | |
193 | =item schedule |
205 | =item schedule |
194 | |
206 | |
195 | Calls the scheduler. Please note that the current process will not be put |
207 | Calls the scheduler. Please note that the current coroutine will not be put |
196 | into the ready queue, so calling this function usually means you will |
208 | into the ready queue, so calling this function usually means you will |
197 | never be called again. |
209 | never be called again unless something else (e.g. an event handler) calls |
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210 | ready. |
198 | |
211 | |
199 | =cut |
212 | The canonical way to wait on external events is this: |
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213 | |
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214 | { |
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215 | # remember current coroutine |
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216 | my $current = $Coro::current; |
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217 | |
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218 | # register a hypothetical event handler |
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219 | on_event_invoke sub { |
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220 | # wake up sleeping coroutine |
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221 | $current->ready; |
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222 | undef $current; |
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223 | }; |
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224 | |
|
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225 | # call schedule until event occured. |
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226 | # in case we are woken up for other reasons |
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227 | # (current still defined), loop. |
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228 | Coro::schedule while $current; |
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229 | } |
200 | |
230 | |
201 | =item cede |
231 | =item cede |
202 | |
232 | |
203 | "Cede" to other processes. This function puts the current process into the |
233 | "Cede" to other coroutines. This function puts the current coroutine into the |
204 | ready queue and calls C<schedule>, which has the effect of giving up the |
234 | ready queue and calls C<schedule>, which has the effect of giving up the |
205 | current "timeslice" to other coroutines of the same or higher priority. |
235 | current "timeslice" to other coroutines of the same or higher priority. |
206 | |
236 | |
207 | =cut |
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208 | |
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209 | =item terminate [arg...] |
237 | =item terminate [arg...] |
210 | |
238 | |
211 | Terminates the current process with the given status values (see L<cancel>). |
239 | Terminates the current coroutine with the given status values (see L<cancel>). |
212 | |
240 | |
213 | =cut |
241 | =cut |
214 | |
242 | |
215 | sub terminate { |
243 | sub terminate { |
216 | $current->cancel (@_); |
244 | $current->cancel (@_); |
… | |
… | |
218 | |
246 | |
219 | =back |
247 | =back |
220 | |
248 | |
221 | # dynamic methods |
249 | # dynamic methods |
222 | |
250 | |
223 | =head2 PROCESS METHODS |
251 | =head2 COROUTINE METHODS |
224 | |
252 | |
225 | These are the methods you can call on process objects. |
253 | These are the methods you can call on coroutine objects. |
226 | |
254 | |
227 | =over 4 |
255 | =over 4 |
228 | |
256 | |
229 | =item new Coro \&sub [, @args...] |
257 | =item new Coro \&sub [, @args...] |
230 | |
258 | |
231 | Create a new process and return it. When the sub returns the process |
259 | Create a new coroutine and return it. When the sub returns the coroutine |
232 | automatically terminates as if C<terminate> with the returned values were |
260 | automatically terminates as if C<terminate> with the returned values were |
233 | called. To make the process run you must first put it into the ready queue |
261 | called. To make the coroutine run you must first put it into the ready queue |
234 | by calling the ready method. |
262 | by calling the ready method. |
235 | |
263 | |
236 | =cut |
264 | Calling C<exit> in a coroutine will not work correctly, so do not do that. |
237 | |
265 | |
|
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266 | =cut |
|
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267 | |
238 | sub _new_coro { |
268 | sub _run_coro { |
239 | $current->_clear_idle_sp; # set the idle sp on the following cede |
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240 | _set_cede_self; # ensures that cede cede's us first |
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241 | cede; |
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242 | terminate &{+shift}; |
269 | terminate &{+shift}; |
243 | } |
270 | } |
244 | |
271 | |
245 | sub new { |
272 | sub new { |
246 | my $class = shift; |
273 | my $class = shift; |
247 | |
274 | |
248 | $class->SUPER::new (\&_new_coro, @_) |
275 | $class->SUPER::new (\&_run_coro, @_) |
249 | } |
276 | } |
250 | |
277 | |
251 | =item $process->ready |
278 | =item $success = $coroutine->ready |
252 | |
279 | |
253 | Put the given process into the ready queue. |
280 | Put the given coroutine into the ready queue (according to it's priority) |
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281 | and return true. If the coroutine is already in the ready queue, do nothing |
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282 | and return false. |
254 | |
283 | |
255 | =cut |
284 | =item $is_ready = $coroutine->is_ready |
256 | |
285 | |
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286 | Return wether the coroutine is currently the ready queue or not, |
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287 | |
257 | =item $process->cancel (arg...) |
288 | =item $coroutine->cancel (arg...) |
258 | |
289 | |
259 | Terminates the given process and makes it return the given arguments as |
290 | Terminates the given coroutine and makes it return the given arguments as |
260 | status (default: the empty list). |
291 | status (default: the empty list). |
261 | |
292 | |
262 | =cut |
293 | =cut |
263 | |
294 | |
264 | sub cancel { |
295 | sub cancel { |
… | |
… | |
267 | push @destroy, $self; |
298 | push @destroy, $self; |
268 | $manager->ready; |
299 | $manager->ready; |
269 | &schedule if $current == $self; |
300 | &schedule if $current == $self; |
270 | } |
301 | } |
271 | |
302 | |
272 | =item $process->join |
303 | =item $coroutine->join |
273 | |
304 | |
274 | Wait until the coroutine terminates and return any values given to the |
305 | Wait until the coroutine terminates and return any values given to the |
275 | C<terminate> or C<cancel> functions. C<join> can be called multiple times |
306 | C<terminate> or C<cancel> functions. C<join> can be called multiple times |
276 | from multiple processes. |
307 | from multiple coroutine. |
277 | |
308 | |
278 | =cut |
309 | =cut |
279 | |
310 | |
280 | sub join { |
311 | sub join { |
281 | my $self = shift; |
312 | my $self = shift; |
… | |
… | |
284 | &schedule; |
315 | &schedule; |
285 | } |
316 | } |
286 | wantarray ? @{$self->{status}} : $self->{status}[0]; |
317 | wantarray ? @{$self->{status}} : $self->{status}[0]; |
287 | } |
318 | } |
288 | |
319 | |
289 | =item $oldprio = $process->prio ($newprio) |
320 | =item $oldprio = $coroutine->prio ($newprio) |
290 | |
321 | |
291 | Sets (or gets, if the argument is missing) the priority of the |
322 | Sets (or gets, if the argument is missing) the priority of the |
292 | process. Higher priority processes get run before lower priority |
323 | coroutine. Higher priority coroutines get run before lower priority |
293 | processes. Priorities are small signed integers (currently -4 .. +3), |
324 | coroutines. Priorities are small signed integers (currently -4 .. +3), |
294 | that you can refer to using PRIO_xxx constants (use the import tag :prio |
325 | that you can refer to using PRIO_xxx constants (use the import tag :prio |
295 | to get then): |
326 | to get then): |
296 | |
327 | |
297 | PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN |
328 | PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN |
298 | 3 > 1 > 0 > -1 > -3 > -4 |
329 | 3 > 1 > 0 > -1 > -3 > -4 |
… | |
… | |
301 | current->prio(PRIO_HIGH); |
332 | current->prio(PRIO_HIGH); |
302 | |
333 | |
303 | The idle coroutine ($Coro::idle) always has a lower priority than any |
334 | The idle coroutine ($Coro::idle) always has a lower priority than any |
304 | existing coroutine. |
335 | existing coroutine. |
305 | |
336 | |
306 | Changing the priority of the current process will take effect immediately, |
337 | Changing the priority of the current coroutine will take effect immediately, |
307 | but changing the priority of processes in the ready queue (but not |
338 | but changing the priority of coroutines in the ready queue (but not |
308 | running) will only take effect after the next schedule (of that |
339 | running) will only take effect after the next schedule (of that |
309 | process). This is a bug that will be fixed in some future version. |
340 | coroutine). This is a bug that will be fixed in some future version. |
310 | |
341 | |
311 | =item $newprio = $process->nice ($change) |
342 | =item $newprio = $coroutine->nice ($change) |
312 | |
343 | |
313 | Similar to C<prio>, but subtract the given value from the priority (i.e. |
344 | Similar to C<prio>, but subtract the given value from the priority (i.e. |
314 | higher values mean lower priority, just as in unix). |
345 | higher values mean lower priority, just as in unix). |
315 | |
346 | |
316 | =item $olddesc = $process->desc ($newdesc) |
347 | =item $olddesc = $coroutine->desc ($newdesc) |
317 | |
348 | |
318 | Sets (or gets in case the argument is missing) the description for this |
349 | Sets (or gets in case the argument is missing) the description for this |
319 | process. This is just a free-form string you can associate with a process. |
350 | coroutine. This is just a free-form string you can associate with a coroutine. |
320 | |
351 | |
321 | =cut |
352 | =cut |
322 | |
353 | |
323 | sub desc { |
354 | sub desc { |
324 | my $old = $_[0]{desc}; |
355 | my $old = $_[0]{desc}; |
… | |
… | |
326 | $old; |
357 | $old; |
327 | } |
358 | } |
328 | |
359 | |
329 | =back |
360 | =back |
330 | |
361 | |
|
|
362 | =head2 GLOBAL FUNCTIONS |
|
|
363 | |
|
|
364 | =over 4 |
|
|
365 | |
|
|
366 | =item Coro::nready |
|
|
367 | |
|
|
368 | Returns the number of coroutines that are currently in the ready state, |
|
|
369 | i.e. that can be swicthed to. The value C<0> means that the only runnable |
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370 | coroutine is the currently running one, so C<cede> would have no effect, |
|
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371 | and C<schedule> would cause a deadlock unless there is an idle handler |
|
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372 | that wakes up some coroutines. |
|
|
373 | |
|
|
374 | =item unblock_sub { ... } |
|
|
375 | |
|
|
376 | This utility function takes a BLOCK or code reference and "unblocks" it, |
|
|
377 | returning the new coderef. This means that the new coderef will return |
|
|
378 | immediately without blocking, returning nothing, while the original code |
|
|
379 | ref will be called (with parameters) from within its own coroutine. |
|
|
380 | |
|
|
381 | The reason this fucntion exists is that many event libraries (such as the |
|
|
382 | venerable L<Event|Event> module) are not coroutine-safe (a weaker form |
|
|
383 | of thread-safety). This means you must not block within event callbacks, |
|
|
384 | otherwise you might suffer from crashes or worse. |
|
|
385 | |
|
|
386 | This function allows your callbacks to block by executing them in another |
|
|
387 | coroutine where it is safe to block. One example where blocking is handy |
|
|
388 | is when you use the L<Coro::AIO|Coro::AIO> functions to save results to |
|
|
389 | disk. |
|
|
390 | |
|
|
391 | In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when |
|
|
392 | creating event callbacks that want to block. |
|
|
393 | |
|
|
394 | =cut |
|
|
395 | |
|
|
396 | our @unblock_pool; |
|
|
397 | our @unblock_queue; |
|
|
398 | our $UNBLOCK_POOL_SIZE = 2; |
|
|
399 | |
|
|
400 | sub unblock_handler_ { |
|
|
401 | while () { |
|
|
402 | my ($cb, @arg) = @{ delete $Coro::current->{arg} }; |
|
|
403 | $cb->(@arg); |
|
|
404 | |
|
|
405 | last if @unblock_pool >= $UNBLOCK_POOL_SIZE; |
|
|
406 | push @unblock_pool, $Coro::current; |
|
|
407 | schedule; |
|
|
408 | } |
|
|
409 | } |
|
|
410 | |
|
|
411 | our $unblock_scheduler = async { |
|
|
412 | while () { |
|
|
413 | while (my $cb = pop @unblock_queue) { |
|
|
414 | my $handler = (pop @unblock_pool or new Coro \&unblock_handler_); |
|
|
415 | $handler->{arg} = $cb; |
|
|
416 | $handler->ready; |
|
|
417 | cede; |
|
|
418 | } |
|
|
419 | |
|
|
420 | schedule; |
|
|
421 | } |
|
|
422 | }; |
|
|
423 | |
|
|
424 | sub unblock_sub(&) { |
|
|
425 | my $cb = shift; |
|
|
426 | |
|
|
427 | sub { |
|
|
428 | push @unblock_queue, [$cb, @_]; |
|
|
429 | $unblock_scheduler->ready; |
|
|
430 | } |
|
|
431 | } |
|
|
432 | |
|
|
433 | =back |
|
|
434 | |
331 | =cut |
435 | =cut |
332 | |
436 | |
333 | 1; |
437 | 1; |
334 | |
438 | |
335 | =head1 BUGS/LIMITATIONS |
439 | =head1 BUGS/LIMITATIONS |