… | |
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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 used in this module also |
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26 | guarantees 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 = '3.01'; |
55 | our $VERSION = '3.8'; |
47 | |
56 | |
48 | our @EXPORT = qw(async cede schedule terminate current unblock_sub); |
57 | our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); |
49 | our %EXPORT_TAGS = ( |
58 | our %EXPORT_TAGS = ( |
50 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
59 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
51 | ); |
60 | ); |
52 | our @EXPORT_OK = @{$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 $init; |
57 | |
66 | |
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99 | |
108 | |
100 | The current coroutine (the last coroutine switched to). The initial value |
109 | The current coroutine (the last coroutine switched to). The initial value |
101 | is C<$main> (of course). |
110 | is C<$main> (of course). |
102 | |
111 | |
103 | 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 |
104 | 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 |
105 | C<Coro::current> function instead. |
114 | C<Coro::current> function instead. |
106 | |
115 | |
107 | =cut |
116 | =cut |
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117 | |
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118 | $main->{desc} = "[main::]"; |
108 | |
119 | |
109 | # maybe some other module used Coro::Specific before... |
120 | # maybe some other module used Coro::Specific before... |
110 | $main->{specific} = $current->{specific} |
121 | $main->{specific} = $current->{specific} |
111 | if $current; |
122 | if $current; |
112 | |
123 | |
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132 | $idle = sub { |
143 | $idle = sub { |
133 | require Carp; |
144 | require Carp; |
134 | Carp::croak ("FATAL: deadlock detected"); |
145 | Carp::croak ("FATAL: deadlock detected"); |
135 | }; |
146 | }; |
136 | |
147 | |
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148 | sub _cancel { |
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149 | my ($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 $self->{destroy_cb}) || []}; |
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158 | } |
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159 | |
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160 | sub _do_trace_sub { |
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161 | &{$current->{_trace_sub_cb}} |
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162 | } |
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163 | |
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164 | sub _do_trace_line { |
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165 | &{$current->{_trace_line_cb}} |
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166 | } |
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167 | |
137 | # this coroutine is necessary because a coroutine |
168 | # this coroutine is necessary because a coroutine |
138 | # cannot destroy itself. |
169 | # cannot destroy itself. |
139 | my @destroy; |
170 | my @destroy; |
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171 | my $manager; |
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172 | |
140 | my $manager; $manager = new Coro sub { |
173 | $manager = new Coro sub { |
141 | while () { |
174 | while () { |
142 | # by overwriting the state object with the manager we destroy it |
175 | (shift @destroy)->_cancel |
143 | # while still being able to schedule this coroutine (in case it has |
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144 | # been readied multiple times. this is harmless since the manager |
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145 | # can be called as many times as neccessary and will always |
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146 | # remove itself from the runqueue |
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147 | while (@destroy) { |
176 | while @destroy; |
148 | my $coro = pop @destroy; |
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149 | $coro->{status} ||= []; |
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150 | $_->ready for @{delete $coro->{join} || []}; |
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151 | |
177 | |
152 | # the next line destroys the coro state, but keeps the |
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153 | # coroutine itself intact (we basically make it a zombie |
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154 | # coroutine that always runs the manager thread, so it's possible |
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155 | # to transfer() to this coroutine). |
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156 | $coro->_clone_state_from ($manager); |
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157 | } |
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158 | &schedule; |
178 | &schedule; |
159 | } |
179 | } |
160 | }; |
180 | }; |
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181 | $manager->desc ("[coro manager]"); |
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182 | $manager->prio (PRIO_MAX); |
161 | |
183 | |
162 | # static methods. not really. |
184 | # static methods. not really. |
163 | |
185 | |
164 | =back |
186 | =back |
165 | |
187 | |
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… | |
173 | |
195 | |
174 | Create a new asynchronous coroutine and return it's coroutine object |
196 | Create a new asynchronous coroutine and return it's coroutine object |
175 | (usually unused). When the sub returns the new coroutine is automatically |
197 | (usually unused). When the sub returns the new coroutine is automatically |
176 | terminated. |
198 | terminated. |
177 | |
199 | |
178 | Calling C<exit> in a coroutine will not work correctly, so do not do that. |
200 | Calling C<exit> in a coroutine will do the same as calling exit outside |
179 | |
201 | the coroutine. Likewise, when the coroutine dies, the program will exit, |
180 | When the coroutine dies, the program will exit, just as in the main |
202 | just as it would in the main program. |
181 | program. |
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182 | |
203 | |
183 | # create a new coroutine that just prints its arguments |
204 | # create a new coroutine that just prints its arguments |
184 | async { |
205 | async { |
185 | print "@_\n"; |
206 | print "@_\n"; |
186 | } 1,2,3,4; |
207 | } 1,2,3,4; |
187 | |
208 | |
188 | =cut |
209 | =cut |
189 | |
210 | |
190 | sub async(&@) { |
211 | sub async(&@) { |
191 | my $pid = new Coro @_; |
212 | my $coro = new Coro @_; |
192 | $pid->ready; |
213 | $coro->ready; |
193 | $pid |
214 | $coro |
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215 | } |
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216 | |
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217 | =item async_pool { ... } [@args...] |
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218 | |
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219 | Similar to C<async>, but uses a coroutine pool, so you should not call |
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220 | terminate or join (although you are allowed to), and you get a coroutine |
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221 | that might have executed other code already (which can be good or bad :). |
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222 | |
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223 | Also, the block is executed in an C<eval> context and a warning will be |
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224 | issued in case of an exception instead of terminating the program, as |
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225 | C<async> does. As the coroutine is being reused, stuff like C<on_destroy> |
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226 | will not work in the expected way, unless you call terminate or cancel, |
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227 | which somehow defeats the purpose of pooling. |
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228 | |
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229 | The priority will be reset to C<0> after each job, otherwise the coroutine |
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230 | will be re-used "as-is". |
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231 | |
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232 | The pool size is limited to 8 idle coroutines (this can be adjusted by |
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233 | changing $Coro::POOL_SIZE), and there can be as many non-idle coros as |
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234 | required. |
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235 | |
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236 | If you are concerned about pooled coroutines growing a lot because a |
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237 | single C<async_pool> used a lot of stackspace you can e.g. C<async_pool |
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238 | { terminate }> once per second or so to slowly replenish the pool. In |
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239 | addition to that, when the stacks used by a handler grows larger than 16kb |
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240 | (adjustable with $Coro::POOL_RSS) it will also exit. |
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241 | |
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242 | =cut |
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243 | |
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244 | our $POOL_SIZE = 8; |
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245 | our $POOL_RSS = 16 * 1024; |
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246 | our @async_pool; |
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247 | |
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248 | sub pool_handler { |
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249 | my $cb; |
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250 | |
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251 | while () { |
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252 | eval { |
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253 | while () { |
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254 | _pool_1 $cb; |
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255 | &$cb; |
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256 | _pool_2 $cb; |
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257 | &schedule; |
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258 | } |
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259 | }; |
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260 | |
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261 | last if $@ eq "\3terminate\2\n"; |
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262 | warn $@ if $@; |
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263 | } |
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264 | } |
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265 | |
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266 | sub async_pool(&@) { |
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267 | # this is also inlined into the unlock_scheduler |
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268 | my $coro = (pop @async_pool) || new Coro \&pool_handler; |
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269 | |
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270 | $coro->{_invoke} = [@_]; |
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271 | $coro->ready; |
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272 | |
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273 | $coro |
194 | } |
274 | } |
195 | |
275 | |
196 | =item schedule |
276 | =item schedule |
197 | |
277 | |
198 | Calls the scheduler. Please note that the current coroutine will not be put |
278 | Calls the scheduler. Please note that the current coroutine will not be put |
… | |
… | |
211 | # wake up sleeping coroutine |
291 | # wake up sleeping coroutine |
212 | $current->ready; |
292 | $current->ready; |
213 | undef $current; |
293 | undef $current; |
214 | }; |
294 | }; |
215 | |
295 | |
216 | # call schedule until event occured. |
296 | # call schedule until event occurred. |
217 | # in case we are woken up for other reasons |
297 | # in case we are woken up for other reasons |
218 | # (current still defined), loop. |
298 | # (current still defined), loop. |
219 | Coro::schedule while $current; |
299 | Coro::schedule while $current; |
220 | } |
300 | } |
221 | |
301 | |
222 | =item cede |
302 | =item cede |
223 | |
303 | |
224 | "Cede" to other coroutines. This function puts the current coroutine into the |
304 | "Cede" to other coroutines. This function puts the current coroutine into the |
225 | ready queue and calls C<schedule>, which has the effect of giving up the |
305 | ready queue and calls C<schedule>, which has the effect of giving up the |
226 | current "timeslice" to other coroutines of the same or higher priority. |
306 | current "timeslice" to other coroutines of the same or higher priority. |
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307 | |
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308 | Returns true if at least one coroutine switch has happened. |
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309 | |
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310 | =item Coro::cede_notself |
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311 | |
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312 | Works like cede, but is not exported by default and will cede to any |
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313 | coroutine, regardless of priority, once. |
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314 | |
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315 | Returns true if at least one coroutine switch has happened. |
227 | |
316 | |
228 | =item terminate [arg...] |
317 | =item terminate [arg...] |
229 | |
318 | |
230 | Terminates the current coroutine with the given status values (see L<cancel>). |
319 | Terminates the current coroutine with the given status values (see L<cancel>). |
231 | |
320 | |
… | |
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250 | Create a new coroutine and return it. When the sub returns the coroutine |
339 | Create a new coroutine and return it. When the sub returns the coroutine |
251 | automatically terminates as if C<terminate> with the returned values were |
340 | automatically terminates as if C<terminate> with the returned values were |
252 | called. To make the coroutine run you must first put it into the ready queue |
341 | called. To make the coroutine run you must first put it into the ready queue |
253 | by calling the ready method. |
342 | by calling the ready method. |
254 | |
343 | |
255 | Calling C<exit> in a coroutine will not work correctly, so do not do that. |
344 | See C<async> for additional discussion. |
256 | |
345 | |
257 | =cut |
346 | =cut |
258 | |
347 | |
259 | sub _run_coro { |
348 | sub _run_coro { |
260 | terminate &{+shift}; |
349 | terminate &{+shift}; |
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277 | Return wether the coroutine is currently the ready queue or not, |
366 | Return wether the coroutine is currently the ready queue or not, |
278 | |
367 | |
279 | =item $coroutine->cancel (arg...) |
368 | =item $coroutine->cancel (arg...) |
280 | |
369 | |
281 | Terminates the given coroutine and makes it return the given arguments as |
370 | Terminates the given coroutine and makes it return the given arguments as |
282 | status (default: the empty list). |
371 | status (default: the empty list). Never returns if the coroutine is the |
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372 | current coroutine. |
283 | |
373 | |
284 | =cut |
374 | =cut |
285 | |
375 | |
286 | sub cancel { |
376 | sub cancel { |
287 | my $self = shift; |
377 | my $self = shift; |
288 | $self->{status} = [@_]; |
378 | $self->{status} = [@_]; |
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379 | |
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380 | if ($current == $self) { |
289 | push @destroy, $self; |
381 | push @destroy, $self; |
290 | $manager->ready; |
382 | $manager->ready; |
291 | &schedule if $current == $self; |
383 | &schedule while 1; |
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384 | } else { |
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385 | $self->_cancel; |
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386 | } |
292 | } |
387 | } |
293 | |
388 | |
294 | =item $coroutine->join |
389 | =item $coroutine->join |
295 | |
390 | |
296 | Wait until the coroutine terminates and return any values given to the |
391 | Wait until the coroutine terminates and return any values given to the |
… | |
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299 | |
394 | |
300 | =cut |
395 | =cut |
301 | |
396 | |
302 | sub join { |
397 | sub join { |
303 | my $self = shift; |
398 | my $self = shift; |
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399 | |
304 | unless ($self->{status}) { |
400 | unless ($self->{status}) { |
305 | push @{$self->{join}}, $current; |
401 | my $current = $current; |
306 | &schedule; |
402 | |
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403 | push @{$self->{destroy_cb}}, sub { |
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404 | $current->ready; |
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405 | undef $current; |
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406 | }; |
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407 | |
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408 | &schedule while $current; |
307 | } |
409 | } |
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410 | |
308 | wantarray ? @{$self->{status}} : $self->{status}[0]; |
411 | wantarray ? @{$self->{status}} : $self->{status}[0]; |
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412 | } |
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413 | |
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414 | =item $coroutine->on_destroy (\&cb) |
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415 | |
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416 | Registers a callback that is called when this coroutine gets destroyed, |
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417 | but before it is joined. The callback gets passed the terminate arguments, |
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418 | if any. |
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419 | |
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420 | =cut |
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421 | |
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422 | sub on_destroy { |
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423 | my ($self, $cb) = @_; |
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424 | |
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425 | push @{ $self->{destroy_cb} }, $cb; |
309 | } |
426 | } |
310 | |
427 | |
311 | =item $oldprio = $coroutine->prio ($newprio) |
428 | =item $oldprio = $coroutine->prio ($newprio) |
312 | |
429 | |
313 | Sets (or gets, if the argument is missing) the priority of the |
430 | Sets (or gets, if the argument is missing) the priority of the |
… | |
… | |
348 | $old; |
465 | $old; |
349 | } |
466 | } |
350 | |
467 | |
351 | =back |
468 | =back |
352 | |
469 | |
353 | =head2 UTILITY FUNCTIONS |
470 | =head2 GLOBAL FUNCTIONS |
354 | |
471 | |
355 | =over 4 |
472 | =over 4 |
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473 | |
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474 | =item Coro::nready |
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475 | |
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476 | Returns the number of coroutines that are currently in the ready state, |
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477 | i.e. that can be switched to. The value C<0> means that the only runnable |
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478 | coroutine is the currently running one, so C<cede> would have no effect, |
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479 | and C<schedule> would cause a deadlock unless there is an idle handler |
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480 | that wakes up some coroutines. |
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481 | |
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482 | =item my $guard = Coro::guard { ... } |
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483 | |
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484 | This creates and returns a guard object. Nothing happens until the object |
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485 | gets destroyed, in which case the codeblock given as argument will be |
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486 | executed. This is useful to free locks or other resources in case of a |
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487 | runtime error or when the coroutine gets canceled, as in both cases the |
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488 | guard block will be executed. The guard object supports only one method, |
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489 | C<< ->cancel >>, which will keep the codeblock from being executed. |
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490 | |
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491 | Example: set some flag and clear it again when the coroutine gets canceled |
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492 | or the function returns: |
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493 | |
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494 | sub do_something { |
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495 | my $guard = Coro::guard { $busy = 0 }; |
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496 | $busy = 1; |
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497 | |
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498 | # do something that requires $busy to be true |
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499 | } |
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500 | |
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501 | =cut |
|
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502 | |
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503 | sub guard(&) { |
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504 | bless \(my $cb = $_[0]), "Coro::guard" |
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505 | } |
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506 | |
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507 | sub Coro::guard::cancel { |
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508 | ${$_[0]} = sub { }; |
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509 | } |
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510 | |
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511 | sub Coro::guard::DESTROY { |
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512 | ${$_[0]}->(); |
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513 | } |
|
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514 | |
356 | |
515 | |
357 | =item unblock_sub { ... } |
516 | =item unblock_sub { ... } |
358 | |
517 | |
359 | This utility function takes a BLOCK or code reference and "unblocks" it, |
518 | This utility function takes a BLOCK or code reference and "unblocks" it, |
360 | returning the new coderef. This means that the new coderef will return |
519 | returning the new coderef. This means that the new coderef will return |
361 | immediately without blocking, returning nothing, while the original code |
520 | immediately without blocking, returning nothing, while the original code |
362 | ref will be called (with parameters) from within its own coroutine. |
521 | ref will be called (with parameters) from within its own coroutine. |
363 | |
522 | |
364 | The reason this fucntion exists is that many event libraries (such as the |
523 | The reason this function exists is that many event libraries (such as the |
365 | venerable L<Event|Event> module) are not coroutine-safe (a weaker form |
524 | venerable L<Event|Event> module) are not coroutine-safe (a weaker form |
366 | of thread-safety). This means you must not block within event callbacks, |
525 | of thread-safety). This means you must not block within event callbacks, |
367 | otherwise you might suffer from crashes or worse. |
526 | otherwise you might suffer from crashes or worse. |
368 | |
527 | |
369 | This function allows your callbacks to block by executing them in another |
528 | This function allows your callbacks to block by executing them in another |
… | |
… | |
374 | In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when |
533 | In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when |
375 | creating event callbacks that want to block. |
534 | creating event callbacks that want to block. |
376 | |
535 | |
377 | =cut |
536 | =cut |
378 | |
537 | |
379 | our @unblock_pool; |
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380 | our @unblock_queue; |
538 | our @unblock_queue; |
381 | our $UNBLOCK_POOL_SIZE = 2; |
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382 | |
539 | |
383 | sub unblock_handler_ { |
540 | # we create a special coro because we want to cede, |
384 | while () { |
541 | # to reduce pressure on the coro pool (because most callbacks |
385 | my ($cb, @arg) = @{ delete $Coro::current->{arg} }; |
542 | # return immediately and can be reused) and because we cannot cede |
386 | $cb->(@arg); |
543 | # inside an event callback. |
387 | |
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388 | last if @unblock_pool >= $UNBLOCK_POOL_SIZE; |
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389 | push @unblock_pool, $Coro::current; |
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390 | schedule; |
|
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391 | } |
|
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392 | } |
|
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393 | |
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394 | our $unblock_scheduler = async { |
544 | our $unblock_scheduler = new Coro sub { |
395 | while () { |
545 | while () { |
396 | while (my $cb = pop @unblock_queue) { |
546 | while (my $cb = pop @unblock_queue) { |
397 | my $handler = (pop @unblock_pool or new Coro \&unblock_handler_); |
547 | # this is an inlined copy of async_pool |
398 | $handler->{arg} = $cb; |
548 | my $coro = (pop @async_pool) || new Coro \&pool_handler; |
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|
549 | |
|
|
550 | $coro->{_invoke} = $cb; |
399 | $handler->ready; |
551 | $coro->ready; |
400 | cede; |
552 | cede; # for short-lived callbacks, this reduces pressure on the coro pool |
401 | } |
553 | } |
402 | |
554 | schedule; # sleep well |
403 | schedule; |
|
|
404 | } |
555 | } |
405 | }; |
556 | }; |
|
|
557 | $unblock_scheduler->desc ("[unblock_sub scheduler]"); |
406 | |
558 | |
407 | sub unblock_sub(&) { |
559 | sub unblock_sub(&) { |
408 | my $cb = shift; |
560 | my $cb = shift; |
409 | |
561 | |
410 | sub { |
562 | sub { |
411 | push @unblock_queue, [$cb, @_]; |
563 | unshift @unblock_queue, [$cb, @_]; |
412 | $unblock_scheduler->ready; |
564 | $unblock_scheduler->ready; |
413 | } |
565 | } |
414 | } |
566 | } |
415 | |
567 | |
416 | =back |
568 | =back |
… | |
… | |
423 | |
575 | |
424 | - you must make very sure that no coro is still active on global |
576 | - you must make very sure that no coro is still active on global |
425 | destruction. very bad things might happen otherwise (usually segfaults). |
577 | destruction. very bad things might happen otherwise (usually segfaults). |
426 | |
578 | |
427 | - this module is not thread-safe. You should only ever use this module |
579 | - this module is not thread-safe. You should only ever use this module |
428 | from the same thread (this requirement might be losened in the future |
580 | from the same thread (this requirement might be loosened in the future |
429 | to allow per-thread schedulers, but Coro::State does not yet allow |
581 | to allow per-thread schedulers, but Coro::State does not yet allow |
430 | this). |
582 | this). |
431 | |
583 | |
432 | =head1 SEE ALSO |
584 | =head1 SEE ALSO |
433 | |
585 | |