… | |
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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 | |
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… | |
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 = '3.0'; |
55 | our $VERSION = '3.3'; |
47 | |
56 | |
48 | our @EXPORT = qw(async cede schedule terminate current unblock_sub); |
57 | our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); |
49 | our %EXPORT_TAGS = ( |
58 | our %EXPORT_TAGS = ( |
50 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
59 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
51 | ); |
60 | ); |
52 | our @EXPORT_OK = @{$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, $ref) = (shift, shift); |
67 | my @attrs; |
76 | my @attrs; |
… | |
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105 | C<Coro::current> function instead. |
114 | C<Coro::current> function instead. |
106 | |
115 | |
107 | =cut |
116 | =cut |
108 | |
117 | |
109 | # maybe some other module used Coro::Specific before... |
118 | # maybe some other module used Coro::Specific before... |
110 | if ($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 | |
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129 | handlers), then it must be prepared to be called recursively. |
137 | handlers), then it must be prepared to be called recursively. |
130 | |
138 | |
131 | =cut |
139 | =cut |
132 | |
140 | |
133 | $idle = sub { |
141 | $idle = sub { |
134 | print STDERR "FATAL: deadlock detected\n"; |
142 | require Carp; |
135 | exit (51); |
143 | Carp::croak ("FATAL: deadlock detected"); |
136 | }; |
144 | }; |
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145 | |
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146 | sub _cancel { |
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147 | my ($self) = @_; |
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148 | |
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149 | # free coroutine data and mark as destructed |
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150 | $self->_destroy |
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151 | or return; |
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152 | |
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153 | # call all destruction callbacks |
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154 | $_->(@{$self->{status}}) |
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155 | for @{(delete $self->{destroy_cb}) || []}; |
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156 | } |
137 | |
157 | |
138 | # this coroutine is necessary because a coroutine |
158 | # this coroutine is necessary because a coroutine |
139 | # cannot destroy itself. |
159 | # cannot destroy itself. |
140 | my @destroy; |
160 | my @destroy; |
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161 | my $manager; |
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162 | |
141 | my $manager; $manager = new Coro sub { |
163 | $manager = new Coro sub { |
142 | while () { |
164 | while () { |
143 | # by overwriting the state object with the manager we destroy it |
165 | (shift @destroy)->_cancel |
144 | # while still being able to schedule this coroutine (in case it has |
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145 | # been readied multiple times. this is harmless since the manager |
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146 | # can be called as many times as neccessary and will always |
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147 | # remove itself from the runqueue |
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148 | while (@destroy) { |
166 | while @destroy; |
149 | my $coro = pop @destroy; |
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150 | $coro->{status} ||= []; |
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151 | $_->ready for @{delete $coro->{join} || []}; |
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152 | |
167 | |
153 | # the next line destroys the coro state, but keeps the |
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154 | # coroutine itself intact (we basically make it a zombie |
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155 | # coroutine that always runs the manager thread, so it's possible |
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156 | # to transfer() to this coroutine). |
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157 | $coro->_clone_state_from ($manager); |
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158 | } |
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159 | &schedule; |
168 | &schedule; |
160 | } |
169 | } |
161 | }; |
170 | }; |
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171 | |
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172 | $manager->prio (PRIO_MAX); |
162 | |
173 | |
163 | # static methods. not really. |
174 | # static methods. not really. |
164 | |
175 | |
165 | =back |
176 | =back |
166 | |
177 | |
… | |
… | |
187 | } 1,2,3,4; |
198 | } 1,2,3,4; |
188 | |
199 | |
189 | =cut |
200 | =cut |
190 | |
201 | |
191 | sub async(&@) { |
202 | sub async(&@) { |
192 | my $pid = new Coro @_; |
203 | my $coro = new Coro @_; |
193 | $pid->ready; |
204 | $coro->ready; |
194 | $pid |
205 | $coro |
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206 | } |
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207 | |
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208 | =item async_pool { ... } [@args...] |
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209 | |
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210 | Similar to C<async>, but uses a coroutine pool, so you should not call |
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211 | terminate or join (although you are allowed to), and you get a coroutine |
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212 | that might have executed other code already (which can be good or bad :). |
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213 | |
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214 | Also, the block is executed in an C<eval> context and a warning will be |
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215 | issued in case of an exception instead of terminating the program, as C<async> does. |
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216 | |
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217 | The priority will be reset to C<0> after each job, otherwise the coroutine |
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218 | will be re-used "as-is". |
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219 | |
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220 | The pool size is limited to 8 idle coroutines (this can be adjusted by |
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221 | changing $Coro::POOL_SIZE), and there can be as many non-idle coros as |
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222 | required. |
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223 | |
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224 | If you are concerned about pooled coroutines growing a lot because a |
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225 | single C<async_pool> used a lot of stackspace you can e.g. C<async_pool { |
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226 | terminate }> once per second or so to slowly replenish the pool. |
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227 | |
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228 | =cut |
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229 | |
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230 | our $POOL_SIZE = 8; |
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231 | our @pool; |
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232 | |
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233 | sub pool_handler { |
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234 | while () { |
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235 | my ($cb, @arg) = @{ delete $current->{_invoke} }; |
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236 | |
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237 | eval { |
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238 | $cb->(@arg); |
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239 | }; |
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240 | warn $@ if $@; |
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241 | |
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242 | last if @pool >= $POOL_SIZE; |
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243 | push @pool, $current; |
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244 | |
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245 | $current->prio (0); |
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246 | schedule; |
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247 | } |
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248 | } |
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249 | |
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250 | sub async_pool(&@) { |
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251 | # this is also inlined into the unlock_scheduler |
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252 | my $coro = (pop @pool or new Coro \&pool_handler); |
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253 | |
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254 | $coro->{_invoke} = [@_]; |
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255 | $coro->ready; |
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256 | |
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257 | $coro |
195 | } |
258 | } |
196 | |
259 | |
197 | =item schedule |
260 | =item schedule |
198 | |
261 | |
199 | Calls the scheduler. Please note that the current coroutine will not be put |
262 | Calls the scheduler. Please note that the current coroutine will not be put |
… | |
… | |
224 | |
287 | |
225 | "Cede" to other coroutines. This function puts the current coroutine into the |
288 | "Cede" to other coroutines. This function puts the current coroutine into the |
226 | ready queue and calls C<schedule>, which has the effect of giving up the |
289 | ready queue and calls C<schedule>, which has the effect of giving up the |
227 | current "timeslice" to other coroutines of the same or higher priority. |
290 | current "timeslice" to other coroutines of the same or higher priority. |
228 | |
291 | |
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292 | Returns true if at least one coroutine switch has happened. |
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293 | |
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294 | =item Coro::cede_notself |
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295 | |
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296 | Works like cede, but is not exported by default and will cede to any |
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297 | coroutine, regardless of priority, once. |
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298 | |
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299 | Returns true if at least one coroutine switch has happened. |
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300 | |
229 | =item terminate [arg...] |
301 | =item terminate [arg...] |
230 | |
302 | |
231 | Terminates the current coroutine with the given status values (see L<cancel>). |
303 | Terminates the current coroutine with the given status values (see L<cancel>). |
232 | |
304 | |
233 | =cut |
305 | =cut |
… | |
… | |
255 | |
327 | |
256 | Calling C<exit> in a coroutine will not work correctly, so do not do that. |
328 | Calling C<exit> in a coroutine will not work correctly, so do not do that. |
257 | |
329 | |
258 | =cut |
330 | =cut |
259 | |
331 | |
260 | sub _new_coro { |
332 | sub _run_coro { |
261 | terminate &{+shift}; |
333 | terminate &{+shift}; |
262 | } |
334 | } |
263 | |
335 | |
264 | sub new { |
336 | sub new { |
265 | my $class = shift; |
337 | my $class = shift; |
266 | |
338 | |
267 | $class->SUPER::new (\&_new_coro, @_) |
339 | $class->SUPER::new (\&_run_coro, @_) |
268 | } |
340 | } |
269 | |
341 | |
270 | =item $success = $coroutine->ready |
342 | =item $success = $coroutine->ready |
271 | |
343 | |
272 | Put the given coroutine into the ready queue (according to it's priority) |
344 | Put the given coroutine into the ready queue (according to it's priority) |
… | |
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278 | Return wether the coroutine is currently the ready queue or not, |
350 | Return wether the coroutine is currently the ready queue or not, |
279 | |
351 | |
280 | =item $coroutine->cancel (arg...) |
352 | =item $coroutine->cancel (arg...) |
281 | |
353 | |
282 | Terminates the given coroutine and makes it return the given arguments as |
354 | Terminates the given coroutine and makes it return the given arguments as |
283 | status (default: the empty list). |
355 | status (default: the empty list). Never returns if the coroutine is the |
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356 | current coroutine. |
284 | |
357 | |
285 | =cut |
358 | =cut |
286 | |
359 | |
287 | sub cancel { |
360 | sub cancel { |
288 | my $self = shift; |
361 | my $self = shift; |
289 | $self->{status} = [@_]; |
362 | $self->{status} = [@_]; |
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363 | |
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364 | if ($current == $self) { |
290 | push @destroy, $self; |
365 | push @destroy, $self; |
291 | $manager->ready; |
366 | $manager->ready; |
292 | &schedule if $current == $self; |
367 | &schedule while 1; |
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368 | } else { |
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369 | $self->_cancel; |
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370 | } |
293 | } |
371 | } |
294 | |
372 | |
295 | =item $coroutine->join |
373 | =item $coroutine->join |
296 | |
374 | |
297 | Wait until the coroutine terminates and return any values given to the |
375 | Wait until the coroutine terminates and return any values given to the |
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300 | |
378 | |
301 | =cut |
379 | =cut |
302 | |
380 | |
303 | sub join { |
381 | sub join { |
304 | my $self = shift; |
382 | my $self = shift; |
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383 | |
305 | unless ($self->{status}) { |
384 | unless ($self->{status}) { |
306 | push @{$self->{join}}, $current; |
385 | my $current = $current; |
307 | &schedule; |
386 | |
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387 | push @{$self->{destroy_cb}}, sub { |
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388 | $current->ready; |
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389 | undef $current; |
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390 | }; |
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391 | |
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392 | &schedule while $current; |
308 | } |
393 | } |
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394 | |
309 | wantarray ? @{$self->{status}} : $self->{status}[0]; |
395 | wantarray ? @{$self->{status}} : $self->{status}[0]; |
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396 | } |
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397 | |
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398 | =item $coroutine->on_destroy (\&cb) |
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399 | |
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400 | Registers a callback that is called when this coroutine gets destroyed, |
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401 | but before it is joined. The callback gets passed the terminate arguments, |
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402 | if any. |
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403 | |
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404 | =cut |
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405 | |
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406 | sub on_destroy { |
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407 | my ($self, $cb) = @_; |
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408 | |
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409 | push @{ $self->{destroy_cb} }, $cb; |
310 | } |
410 | } |
311 | |
411 | |
312 | =item $oldprio = $coroutine->prio ($newprio) |
412 | =item $oldprio = $coroutine->prio ($newprio) |
313 | |
413 | |
314 | Sets (or gets, if the argument is missing) the priority of the |
414 | Sets (or gets, if the argument is missing) the priority of the |
… | |
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349 | $old; |
449 | $old; |
350 | } |
450 | } |
351 | |
451 | |
352 | =back |
452 | =back |
353 | |
453 | |
354 | =head2 UTILITY FUNCTIONS |
454 | =head2 GLOBAL FUNCTIONS |
355 | |
455 | |
356 | =over 4 |
456 | =over 4 |
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457 | |
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458 | =item Coro::nready |
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459 | |
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460 | Returns the number of coroutines that are currently in the ready state, |
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461 | i.e. that can be swicthed to. The value C<0> means that the only runnable |
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462 | coroutine is the currently running one, so C<cede> would have no effect, |
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463 | and C<schedule> would cause a deadlock unless there is an idle handler |
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464 | that wakes up some coroutines. |
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465 | |
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466 | =item my $guard = Coro::guard { ... } |
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467 | |
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468 | This creates and returns a guard object. Nothing happens until the objetc |
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469 | gets destroyed, in which case the codeblock given as argument will be |
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470 | executed. This is useful to free locks or other resources in case of a |
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471 | runtime error or when the coroutine gets canceled, as in both cases the |
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472 | guard block will be executed. The guard object supports only one method, |
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473 | C<< ->cancel >>, which will keep the codeblock from being executed. |
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474 | |
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475 | Example: set some flag and clear it again when the coroutine gets canceled |
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476 | or the function returns: |
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477 | |
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478 | sub do_something { |
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479 | my $guard = Coro::guard { $busy = 0 }; |
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480 | $busy = 1; |
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481 | |
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482 | # do something that requires $busy to be true |
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483 | } |
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484 | |
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485 | =cut |
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486 | |
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487 | sub guard(&) { |
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488 | bless \(my $cb = $_[0]), "Coro::guard" |
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489 | } |
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490 | |
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491 | sub Coro::guard::cancel { |
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492 | ${$_[0]} = sub { }; |
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493 | } |
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494 | |
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495 | sub Coro::guard::DESTROY { |
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496 | ${$_[0]}->(); |
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497 | } |
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498 | |
357 | |
499 | |
358 | =item unblock_sub { ... } |
500 | =item unblock_sub { ... } |
359 | |
501 | |
360 | This utility function takes a BLOCK or code reference and "unblocks" it, |
502 | This utility function takes a BLOCK or code reference and "unblocks" it, |
361 | returning the new coderef. This means that the new coderef will return |
503 | returning the new coderef. This means that the new coderef will return |
… | |
… | |
375 | In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when |
517 | In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when |
376 | creating event callbacks that want to block. |
518 | creating event callbacks that want to block. |
377 | |
519 | |
378 | =cut |
520 | =cut |
379 | |
521 | |
380 | our @unblock_pool; |
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381 | our @unblock_queue; |
522 | our @unblock_queue; |
382 | our $UNBLOCK_POOL_SIZE = 2; |
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383 | |
523 | |
384 | sub unblock_handler_ { |
524 | # we create a special coro because we want to cede, |
385 | while () { |
525 | # to reduce pressure on the coro pool (because most callbacks |
386 | my ($cb, @arg) = @{ delete $Coro::current->{arg} }; |
526 | # return immediately and can be reused) and because we cannot cede |
387 | $cb->(@arg); |
527 | # inside an event callback. |
388 | |
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389 | last if @unblock_pool >= $UNBLOCK_POOL_SIZE; |
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390 | push @unblock_pool, $Coro::current; |
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391 | schedule; |
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392 | } |
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393 | } |
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394 | |
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395 | our $unblock_scheduler = async { |
528 | our $unblock_scheduler = async { |
396 | while () { |
529 | while () { |
397 | while (my $cb = pop @unblock_queue) { |
530 | while (my $cb = pop @unblock_queue) { |
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531 | # this is an inlined copy of async_pool |
398 | my $handler = (pop @unblock_pool or new Coro \&unblock_handler_); |
532 | my $coro = (pop @pool or new Coro \&pool_handler); |
399 | $handler->{arg} = $cb; |
533 | |
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534 | $coro->{_invoke} = $cb; |
400 | $handler->ready; |
535 | $coro->ready; |
401 | cede; |
536 | cede; # for short-lived callbacks, this reduces pressure on the coro pool |
402 | } |
537 | } |
403 | |
538 | schedule; # sleep well |
404 | schedule; |
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405 | } |
539 | } |
406 | }; |
540 | }; |
407 | |
541 | |
408 | sub unblock_sub(&) { |
542 | sub unblock_sub(&) { |
409 | my $cb = shift; |
543 | my $cb = shift; |
410 | |
544 | |
411 | sub { |
545 | sub { |
412 | push @unblock_queue, [$cb, @_]; |
546 | unshift @unblock_queue, [$cb, @_]; |
413 | $unblock_scheduler->ready; |
547 | $unblock_scheduler->ready; |
414 | } |
548 | } |
415 | } |
549 | } |
416 | |
550 | |
417 | =back |
551 | =back |