… | |
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20 | |
20 | |
21 | =head1 DESCRIPTION |
21 | =head1 DESCRIPTION |
22 | |
22 | |
23 | This module collection manages coroutines. Coroutines are similar |
23 | This module collection manages coroutines. Coroutines are similar |
24 | to threads but don't run in parallel at the same time even on SMP |
24 | to threads but don't run in parallel at the same time even on SMP |
25 | machines. The specific flavor of coroutine use din this module also |
25 | machines. The specific flavor of coroutine used in this module also |
26 | guarentees you that it will not switch between coroutines unless |
26 | guarantees you that it will not switch between coroutines unless |
27 | necessary, at easily-identified points in your program, so locking and |
27 | necessary, at easily-identified points in your program, so locking and |
28 | parallel access are rarely an issue, making coroutine programming much |
28 | parallel access are rarely an issue, making coroutine programming much |
29 | safer than threads programming. |
29 | safer than threads programming. |
30 | |
30 | |
31 | (Perl, however, does not natively support real threads but instead does a |
31 | (Perl, however, does not natively support real threads but instead does a |
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50 | |
50 | |
51 | our $idle; # idle handler |
51 | our $idle; # idle handler |
52 | our $main; # main coroutine |
52 | our $main; # main coroutine |
53 | our $current; # current coroutine |
53 | our $current; # current coroutine |
54 | |
54 | |
55 | our $VERSION = '3.3'; |
55 | our $VERSION = '3.7'; |
56 | |
56 | |
57 | our @EXPORT = qw(async cede schedule terminate current unblock_sub); |
57 | our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); |
58 | our %EXPORT_TAGS = ( |
58 | our %EXPORT_TAGS = ( |
59 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
59 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
60 | ); |
60 | ); |
61 | our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready)); |
61 | our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready)); |
62 | |
62 | |
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108 | |
108 | |
109 | The current coroutine (the last coroutine switched to). The initial value |
109 | The current coroutine (the last coroutine switched to). The initial value |
110 | is C<$main> (of course). |
110 | is C<$main> (of course). |
111 | |
111 | |
112 | This variable is B<strictly> I<read-only>. It is provided for performance |
112 | This variable is B<strictly> I<read-only>. It is provided for performance |
113 | reasons. If performance is not essentiel you are encouraged to use the |
113 | reasons. If performance is not essential you are encouraged to use the |
114 | C<Coro::current> function instead. |
114 | C<Coro::current> function instead. |
115 | |
115 | |
116 | =cut |
116 | =cut |
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117 | |
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118 | $main->{desc} = "[main::]"; |
117 | |
119 | |
118 | # maybe some other module used Coro::Specific before... |
120 | # maybe some other module used Coro::Specific before... |
119 | $main->{specific} = $current->{specific} |
121 | $main->{specific} = $current->{specific} |
120 | if $current; |
122 | if $current; |
121 | |
123 | |
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141 | $idle = sub { |
143 | $idle = sub { |
142 | require Carp; |
144 | require Carp; |
143 | Carp::croak ("FATAL: deadlock detected"); |
145 | Carp::croak ("FATAL: deadlock detected"); |
144 | }; |
146 | }; |
145 | |
147 | |
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148 | sub _cancel { |
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149 | my ($self) = @_; |
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150 | |
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151 | # free coroutine data and mark as destructed |
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152 | $self->_destroy |
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153 | or return; |
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154 | |
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155 | # call all destruction callbacks |
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156 | $_->(@{$self->{status}}) |
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157 | for @{(delete $self->{destroy_cb}) || []}; |
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158 | } |
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159 | |
146 | # this coroutine is necessary because a coroutine |
160 | # this coroutine is necessary because a coroutine |
147 | # cannot destroy itself. |
161 | # cannot destroy itself. |
148 | my @destroy; |
162 | my @destroy; |
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163 | my $manager; |
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164 | |
149 | my $manager; $manager = new Coro sub { |
165 | $manager = new Coro sub { |
150 | while () { |
166 | while () { |
151 | # by overwriting the state object with the manager we destroy it |
167 | (shift @destroy)->_cancel |
152 | # while still being able to schedule this coroutine (in case it has |
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153 | # been readied multiple times. this is harmless since the manager |
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154 | # can be called as many times as neccessary and will always |
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155 | # remove itself from the runqueue |
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156 | while (@destroy) { |
168 | while @destroy; |
157 | my $coro = pop @destroy; |
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158 | |
169 | |
159 | $coro->{status} ||= []; |
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160 | |
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161 | $_->ready for @{(delete $coro->{join} ) || []}; |
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162 | $_->(@{$coro->{status}}) for @{(delete $coro->{destroy_cb}) || []}; |
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163 | |
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164 | # the next line destroys the coro state, but keeps the |
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165 | # coroutine itself intact (we basically make it a zombie |
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166 | # coroutine that always runs the manager thread, so it's possible |
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167 | # to transfer() to this coroutine). |
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168 | $coro->_clone_state_from ($manager); |
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169 | } |
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170 | &schedule; |
170 | &schedule; |
171 | } |
171 | } |
172 | }; |
172 | }; |
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173 | $manager->desc ("[coro manager]"); |
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174 | $manager->prio (PRIO_MAX); |
173 | |
175 | |
174 | # static methods. not really. |
176 | # static methods. not really. |
175 | |
177 | |
176 | =back |
178 | =back |
177 | |
179 | |
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185 | |
187 | |
186 | Create a new asynchronous coroutine and return it's coroutine object |
188 | Create a new asynchronous coroutine and return it's coroutine object |
187 | (usually unused). When the sub returns the new coroutine is automatically |
189 | (usually unused). When the sub returns the new coroutine is automatically |
188 | terminated. |
190 | terminated. |
189 | |
191 | |
190 | Calling C<exit> in a coroutine will not work correctly, so do not do that. |
192 | Calling C<exit> in a coroutine will do the same as calling exit outside |
191 | |
193 | the coroutine. Likewise, when the coroutine dies, the program will exit, |
192 | When the coroutine dies, the program will exit, just as in the main |
194 | just as it would in the main program. |
193 | program. |
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194 | |
195 | |
195 | # create a new coroutine that just prints its arguments |
196 | # create a new coroutine that just prints its arguments |
196 | async { |
197 | async { |
197 | print "@_\n"; |
198 | print "@_\n"; |
198 | } 1,2,3,4; |
199 | } 1,2,3,4; |
199 | |
200 | |
200 | =cut |
201 | =cut |
201 | |
202 | |
202 | sub async(&@) { |
203 | sub async(&@) { |
203 | my $pid = new Coro @_; |
204 | my $coro = new Coro @_; |
204 | $pid->ready; |
205 | $coro->ready; |
205 | $pid |
206 | $coro |
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207 | } |
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208 | |
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209 | =item async_pool { ... } [@args...] |
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210 | |
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211 | Similar to C<async>, but uses a coroutine pool, so you should not call |
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212 | terminate or join (although you are allowed to), and you get a coroutine |
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213 | that might have executed other code already (which can be good or bad :). |
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214 | |
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215 | Also, the block is executed in an C<eval> context and a warning will be |
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216 | issued in case of an exception instead of terminating the program, as |
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217 | C<async> does. As the coroutine is being reused, stuff like C<on_destroy> |
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218 | will not work in the expected way, unless you call terminate or cancel, |
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219 | which somehow defeats the purpose of pooling. |
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220 | |
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221 | The priority will be reset to C<0> after each job, otherwise the coroutine |
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222 | will be re-used "as-is". |
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223 | |
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224 | The pool size is limited to 8 idle coroutines (this can be adjusted by |
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225 | changing $Coro::POOL_SIZE), and there can be as many non-idle coros as |
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226 | required. |
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227 | |
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228 | If you are concerned about pooled coroutines growing a lot because a |
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229 | single C<async_pool> used a lot of stackspace you can e.g. C<async_pool |
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230 | { terminate }> once per second or so to slowly replenish the pool. In |
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231 | addition to that, when the stacks used by a handler grows larger than 16kb |
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232 | (adjustable with $Coro::POOL_RSS) it will also exit. |
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233 | |
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234 | =cut |
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235 | |
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236 | our $POOL_SIZE = 8; |
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237 | our $POOL_RSS = 16 * 1024; |
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238 | our @async_pool; |
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239 | |
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240 | sub pool_handler { |
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241 | my $cb; |
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242 | |
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243 | while () { |
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244 | eval { |
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245 | while () { |
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246 | # &{&_pool_1 or &terminate}; # crashes, would be ~5% faster |
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247 | $cb = &_pool_1 |
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248 | or &terminate; |
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249 | &$cb; |
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250 | undef $cb; |
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251 | &terminate if &_pool_2; |
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252 | &schedule; |
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253 | } |
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254 | }; |
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255 | |
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256 | warn $@ if $@; |
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257 | } |
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258 | } |
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259 | |
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260 | sub async_pool(&@) { |
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261 | # this is also inlined into the unlock_scheduler |
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262 | my $coro = (pop @async_pool) || new Coro \&pool_handler; |
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263 | |
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264 | $coro->{_invoke} = [@_]; |
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265 | $coro->ready; |
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266 | |
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267 | $coro |
206 | } |
268 | } |
207 | |
269 | |
208 | =item schedule |
270 | =item schedule |
209 | |
271 | |
210 | Calls the scheduler. Please note that the current coroutine will not be put |
272 | Calls the scheduler. Please note that the current coroutine will not be put |
… | |
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223 | # wake up sleeping coroutine |
285 | # wake up sleeping coroutine |
224 | $current->ready; |
286 | $current->ready; |
225 | undef $current; |
287 | undef $current; |
226 | }; |
288 | }; |
227 | |
289 | |
228 | # call schedule until event occured. |
290 | # call schedule until event occurred. |
229 | # in case we are woken up for other reasons |
291 | # in case we are woken up for other reasons |
230 | # (current still defined), loop. |
292 | # (current still defined), loop. |
231 | Coro::schedule while $current; |
293 | Coro::schedule while $current; |
232 | } |
294 | } |
233 | |
295 | |
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235 | |
297 | |
236 | "Cede" to other coroutines. This function puts the current coroutine into the |
298 | "Cede" to other coroutines. This function puts the current coroutine into the |
237 | ready queue and calls C<schedule>, which has the effect of giving up the |
299 | ready queue and calls C<schedule>, which has the effect of giving up the |
238 | current "timeslice" to other coroutines of the same or higher priority. |
300 | current "timeslice" to other coroutines of the same or higher priority. |
239 | |
301 | |
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302 | Returns true if at least one coroutine switch has happened. |
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303 | |
240 | =item Coro::cede_notself |
304 | =item Coro::cede_notself |
241 | |
305 | |
242 | Works like cede, but is not exported by default and will cede to any |
306 | Works like cede, but is not exported by default and will cede to any |
243 | coroutine, regardless of priority, once. |
307 | coroutine, regardless of priority, once. |
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308 | |
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309 | Returns true if at least one coroutine switch has happened. |
244 | |
310 | |
245 | =item terminate [arg...] |
311 | =item terminate [arg...] |
246 | |
312 | |
247 | Terminates the current coroutine with the given status values (see L<cancel>). |
313 | Terminates the current coroutine with the given status values (see L<cancel>). |
248 | |
314 | |
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267 | Create a new coroutine and return it. When the sub returns the coroutine |
333 | Create a new coroutine and return it. When the sub returns the coroutine |
268 | automatically terminates as if C<terminate> with the returned values were |
334 | automatically terminates as if C<terminate> with the returned values were |
269 | called. To make the coroutine run you must first put it into the ready queue |
335 | called. To make the coroutine run you must first put it into the ready queue |
270 | by calling the ready method. |
336 | by calling the ready method. |
271 | |
337 | |
272 | Calling C<exit> in a coroutine will not work correctly, so do not do that. |
338 | See C<async> for additional discussion. |
273 | |
339 | |
274 | =cut |
340 | =cut |
275 | |
341 | |
276 | sub _run_coro { |
342 | sub _run_coro { |
277 | terminate &{+shift}; |
343 | terminate &{+shift}; |
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294 | Return wether the coroutine is currently the ready queue or not, |
360 | Return wether the coroutine is currently the ready queue or not, |
295 | |
361 | |
296 | =item $coroutine->cancel (arg...) |
362 | =item $coroutine->cancel (arg...) |
297 | |
363 | |
298 | Terminates the given coroutine and makes it return the given arguments as |
364 | Terminates the given coroutine and makes it return the given arguments as |
299 | status (default: the empty list). |
365 | status (default: the empty list). Never returns if the coroutine is the |
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366 | current coroutine. |
300 | |
367 | |
301 | =cut |
368 | =cut |
302 | |
369 | |
303 | sub cancel { |
370 | sub cancel { |
304 | my $self = shift; |
371 | my $self = shift; |
305 | $self->{status} = [@_]; |
372 | $self->{status} = [@_]; |
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373 | |
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374 | if ($current == $self) { |
306 | push @destroy, $self; |
375 | push @destroy, $self; |
307 | $manager->ready; |
376 | $manager->ready; |
308 | &schedule if $current == $self; |
377 | &schedule while 1; |
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378 | } else { |
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379 | $self->_cancel; |
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380 | } |
309 | } |
381 | } |
310 | |
382 | |
311 | =item $coroutine->join |
383 | =item $coroutine->join |
312 | |
384 | |
313 | Wait until the coroutine terminates and return any values given to the |
385 | Wait until the coroutine terminates and return any values given to the |
… | |
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316 | |
388 | |
317 | =cut |
389 | =cut |
318 | |
390 | |
319 | sub join { |
391 | sub join { |
320 | my $self = shift; |
392 | my $self = shift; |
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393 | |
321 | unless ($self->{status}) { |
394 | unless ($self->{status}) { |
322 | push @{$self->{join}}, $current; |
395 | my $current = $current; |
323 | &schedule; |
396 | |
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397 | push @{$self->{destroy_cb}}, sub { |
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398 | $current->ready; |
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399 | undef $current; |
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400 | }; |
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401 | |
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402 | &schedule while $current; |
324 | } |
403 | } |
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404 | |
325 | wantarray ? @{$self->{status}} : $self->{status}[0]; |
405 | wantarray ? @{$self->{status}} : $self->{status}[0]; |
326 | } |
406 | } |
327 | |
407 | |
328 | =item $coroutine->on_destroy (\&cb) |
408 | =item $coroutine->on_destroy (\&cb) |
329 | |
409 | |
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386 | =over 4 |
466 | =over 4 |
387 | |
467 | |
388 | =item Coro::nready |
468 | =item Coro::nready |
389 | |
469 | |
390 | Returns the number of coroutines that are currently in the ready state, |
470 | Returns the number of coroutines that are currently in the ready state, |
391 | i.e. that can be swicthed to. The value C<0> means that the only runnable |
471 | i.e. that can be switched to. The value C<0> means that the only runnable |
392 | coroutine is the currently running one, so C<cede> would have no effect, |
472 | coroutine is the currently running one, so C<cede> would have no effect, |
393 | and C<schedule> would cause a deadlock unless there is an idle handler |
473 | and C<schedule> would cause a deadlock unless there is an idle handler |
394 | that wakes up some coroutines. |
474 | that wakes up some coroutines. |
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475 | |
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476 | =item my $guard = Coro::guard { ... } |
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477 | |
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478 | This creates and returns a guard object. Nothing happens until the object |
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479 | gets destroyed, in which case the codeblock given as argument will be |
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480 | executed. This is useful to free locks or other resources in case of a |
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481 | runtime error or when the coroutine gets canceled, as in both cases the |
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482 | guard block will be executed. The guard object supports only one method, |
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483 | C<< ->cancel >>, which will keep the codeblock from being executed. |
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484 | |
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485 | Example: set some flag and clear it again when the coroutine gets canceled |
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486 | or the function returns: |
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487 | |
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488 | sub do_something { |
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489 | my $guard = Coro::guard { $busy = 0 }; |
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490 | $busy = 1; |
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491 | |
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492 | # do something that requires $busy to be true |
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493 | } |
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494 | |
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495 | =cut |
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496 | |
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497 | sub guard(&) { |
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498 | bless \(my $cb = $_[0]), "Coro::guard" |
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499 | } |
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500 | |
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501 | sub Coro::guard::cancel { |
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502 | ${$_[0]} = sub { }; |
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503 | } |
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504 | |
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505 | sub Coro::guard::DESTROY { |
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506 | ${$_[0]}->(); |
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507 | } |
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508 | |
395 | |
509 | |
396 | =item unblock_sub { ... } |
510 | =item unblock_sub { ... } |
397 | |
511 | |
398 | This utility function takes a BLOCK or code reference and "unblocks" it, |
512 | This utility function takes a BLOCK or code reference and "unblocks" it, |
399 | returning the new coderef. This means that the new coderef will return |
513 | returning the new coderef. This means that the new coderef will return |
400 | immediately without blocking, returning nothing, while the original code |
514 | immediately without blocking, returning nothing, while the original code |
401 | ref will be called (with parameters) from within its own coroutine. |
515 | ref will be called (with parameters) from within its own coroutine. |
402 | |
516 | |
403 | The reason this fucntion exists is that many event libraries (such as the |
517 | The reason this function exists is that many event libraries (such as the |
404 | venerable L<Event|Event> module) are not coroutine-safe (a weaker form |
518 | venerable L<Event|Event> module) are not coroutine-safe (a weaker form |
405 | of thread-safety). This means you must not block within event callbacks, |
519 | of thread-safety). This means you must not block within event callbacks, |
406 | otherwise you might suffer from crashes or worse. |
520 | otherwise you might suffer from crashes or worse. |
407 | |
521 | |
408 | This function allows your callbacks to block by executing them in another |
522 | This function allows your callbacks to block by executing them in another |
… | |
… | |
413 | In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when |
527 | In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when |
414 | creating event callbacks that want to block. |
528 | creating event callbacks that want to block. |
415 | |
529 | |
416 | =cut |
530 | =cut |
417 | |
531 | |
418 | our @unblock_pool; |
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419 | our @unblock_queue; |
532 | our @unblock_queue; |
420 | our $UNBLOCK_POOL_SIZE = 2; |
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421 | |
533 | |
422 | sub unblock_handler_ { |
534 | # we create a special coro because we want to cede, |
423 | while () { |
535 | # to reduce pressure on the coro pool (because most callbacks |
424 | my ($cb, @arg) = @{ delete $Coro::current->{arg} }; |
536 | # return immediately and can be reused) and because we cannot cede |
425 | $cb->(@arg); |
537 | # inside an event callback. |
426 | |
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427 | last if @unblock_pool >= $UNBLOCK_POOL_SIZE; |
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428 | push @unblock_pool, $Coro::current; |
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429 | schedule; |
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430 | } |
|
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431 | } |
|
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432 | |
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433 | our $unblock_scheduler = async { |
538 | our $unblock_scheduler = new Coro sub { |
434 | while () { |
539 | while () { |
435 | while (my $cb = pop @unblock_queue) { |
540 | while (my $cb = pop @unblock_queue) { |
436 | my $handler = (pop @unblock_pool or new Coro \&unblock_handler_); |
541 | # this is an inlined copy of async_pool |
437 | $handler->{arg} = $cb; |
542 | my $coro = (pop @async_pool) || new Coro \&pool_handler; |
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543 | |
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544 | $coro->{_invoke} = $cb; |
438 | $handler->ready; |
545 | $coro->ready; |
439 | cede; |
546 | cede; # for short-lived callbacks, this reduces pressure on the coro pool |
440 | } |
547 | } |
441 | |
548 | schedule; # sleep well |
442 | schedule; |
|
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443 | } |
549 | } |
444 | }; |
550 | }; |
|
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551 | $unblock_scheduler->desc ("[unblock_sub scheduler]"); |
445 | |
552 | |
446 | sub unblock_sub(&) { |
553 | sub unblock_sub(&) { |
447 | my $cb = shift; |
554 | my $cb = shift; |
448 | |
555 | |
449 | sub { |
556 | sub { |
450 | push @unblock_queue, [$cb, @_]; |
557 | unshift @unblock_queue, [$cb, @_]; |
451 | $unblock_scheduler->ready; |
558 | $unblock_scheduler->ready; |
452 | } |
559 | } |
453 | } |
560 | } |
454 | |
561 | |
455 | =back |
562 | =back |
… | |
… | |
462 | |
569 | |
463 | - you must make very sure that no coro is still active on global |
570 | - you must make very sure that no coro is still active on global |
464 | destruction. very bad things might happen otherwise (usually segfaults). |
571 | destruction. very bad things might happen otherwise (usually segfaults). |
465 | |
572 | |
466 | - this module is not thread-safe. You should only ever use this module |
573 | - this module is not thread-safe. You should only ever use this module |
467 | from the same thread (this requirement might be losened in the future |
574 | from the same thread (this requirement might be loosened in the future |
468 | to allow per-thread schedulers, but Coro::State does not yet allow |
575 | to allow per-thread schedulers, but Coro::State does not yet allow |
469 | this). |
576 | this). |
470 | |
577 | |
471 | =head1 SEE ALSO |
578 | =head1 SEE ALSO |
472 | |
579 | |