| … | |
… | |
| 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 = '3.0'; |
55 | our $VERSION = '3.3'; |
| 47 | |
56 | |
| 48 | our @EXPORT = qw(async cede schedule terminate current unblock_sub); |
57 | our @EXPORT = qw(async cede schedule terminate current unblock_sub); |
| 49 | our %EXPORT_TAGS = ( |
58 | our %EXPORT_TAGS = ( |
| 50 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
59 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
| 51 | ); |
60 | ); |
| 52 | our @EXPORT_OK = @{$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 | |
| … | |
… | |
| 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 |
| 195 | } |
206 | } |
| 196 | |
207 | |
| 197 | =item schedule |
208 | =item schedule |
| 198 | |
209 | |
| 199 | Calls the scheduler. Please note that the current coroutine will not be put |
210 | Calls the scheduler. Please note that the current coroutine will not be put |
| … | |
… | |
| 224 | |
235 | |
| 225 | "Cede" to other coroutines. This function puts the current coroutine into the |
236 | "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 |
237 | 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. |
238 | current "timeslice" to other coroutines of the same or higher priority. |
| 228 | |
239 | |
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240 | =item Coro::cede_notself |
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241 | |
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242 | Works like cede, but is not exported by default and will cede to any |
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243 | coroutine, regardless of priority, once. |
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244 | |
| 229 | =item terminate [arg...] |
245 | =item terminate [arg...] |
| 230 | |
246 | |
| 231 | Terminates the current coroutine with the given status values (see L<cancel>). |
247 | Terminates the current coroutine with the given status values (see L<cancel>). |
| 232 | |
248 | |
| 233 | =cut |
249 | =cut |
| … | |
… | |
| 255 | |
271 | |
| 256 | Calling C<exit> in a coroutine will not work correctly, so do not do that. |
272 | Calling C<exit> in a coroutine will not work correctly, so do not do that. |
| 257 | |
273 | |
| 258 | =cut |
274 | =cut |
| 259 | |
275 | |
| 260 | sub _new_coro { |
276 | sub _run_coro { |
| 261 | terminate &{+shift}; |
277 | terminate &{+shift}; |
| 262 | } |
278 | } |
| 263 | |
279 | |
| 264 | sub new { |
280 | sub new { |
| 265 | my $class = shift; |
281 | my $class = shift; |
| 266 | |
282 | |
| 267 | $class->SUPER::new (\&_new_coro, @_) |
283 | $class->SUPER::new (\&_run_coro, @_) |
| 268 | } |
284 | } |
| 269 | |
285 | |
| 270 | =item $success = $coroutine->ready |
286 | =item $success = $coroutine->ready |
| 271 | |
287 | |
| 272 | Put the given coroutine into the ready queue (according to it's priority) |
288 | Put the given coroutine into the ready queue (according to it's priority) |
| … | |
… | |
| 278 | Return wether the coroutine is currently the ready queue or not, |
294 | Return wether the coroutine is currently the ready queue or not, |
| 279 | |
295 | |
| 280 | =item $coroutine->cancel (arg...) |
296 | =item $coroutine->cancel (arg...) |
| 281 | |
297 | |
| 282 | Terminates the given coroutine and makes it return the given arguments as |
298 | Terminates the given coroutine and makes it return the given arguments as |
| 283 | status (default: the empty list). |
299 | status (default: the empty list). Never returns if the coroutine is the |
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300 | current coroutine. |
| 284 | |
301 | |
| 285 | =cut |
302 | =cut |
| 286 | |
303 | |
| 287 | sub cancel { |
304 | sub cancel { |
| 288 | my $self = shift; |
305 | my $self = shift; |
| 289 | $self->{status} = [@_]; |
306 | $self->{status} = [@_]; |
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307 | |
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308 | if ($current == $self) { |
| 290 | push @destroy, $self; |
309 | push @destroy, $self; |
| 291 | $manager->ready; |
310 | $manager->ready; |
| 292 | &schedule if $current == $self; |
311 | &schedule while 1; |
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312 | } else { |
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313 | $self->_cancel; |
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314 | } |
| 293 | } |
315 | } |
| 294 | |
316 | |
| 295 | =item $coroutine->join |
317 | =item $coroutine->join |
| 296 | |
318 | |
| 297 | Wait until the coroutine terminates and return any values given to the |
319 | Wait until the coroutine terminates and return any values given to the |
| … | |
… | |
| 300 | |
322 | |
| 301 | =cut |
323 | =cut |
| 302 | |
324 | |
| 303 | sub join { |
325 | sub join { |
| 304 | my $self = shift; |
326 | my $self = shift; |
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327 | |
| 305 | unless ($self->{status}) { |
328 | unless ($self->{status}) { |
| 306 | push @{$self->{join}}, $current; |
329 | my $current = $current; |
| 307 | &schedule; |
330 | |
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331 | push @{$self->{destroy_cb}}, sub { |
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332 | $current->ready; |
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333 | undef $current; |
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334 | }; |
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335 | |
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336 | &schedule while $current; |
| 308 | } |
337 | } |
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338 | |
| 309 | wantarray ? @{$self->{status}} : $self->{status}[0]; |
339 | wantarray ? @{$self->{status}} : $self->{status}[0]; |
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340 | } |
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341 | |
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342 | =item $coroutine->on_destroy (\&cb) |
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343 | |
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344 | Registers a callback that is called when this coroutine gets destroyed, |
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345 | but before it is joined. The callback gets passed the terminate arguments, |
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346 | if any. |
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347 | |
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348 | =cut |
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349 | |
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350 | sub on_destroy { |
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351 | my ($self, $cb) = @_; |
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352 | |
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353 | push @{ $self->{destroy_cb} }, $cb; |
| 310 | } |
354 | } |
| 311 | |
355 | |
| 312 | =item $oldprio = $coroutine->prio ($newprio) |
356 | =item $oldprio = $coroutine->prio ($newprio) |
| 313 | |
357 | |
| 314 | Sets (or gets, if the argument is missing) the priority of the |
358 | Sets (or gets, if the argument is missing) the priority of the |
| … | |
… | |
| 349 | $old; |
393 | $old; |
| 350 | } |
394 | } |
| 351 | |
395 | |
| 352 | =back |
396 | =back |
| 353 | |
397 | |
| 354 | =head2 UTILITY FUNCTIONS |
398 | =head2 GLOBAL FUNCTIONS |
| 355 | |
399 | |
| 356 | =over 4 |
400 | =over 4 |
|
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401 | |
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402 | =item Coro::nready |
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403 | |
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404 | Returns the number of coroutines that are currently in the ready state, |
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405 | i.e. that can be swicthed to. The value C<0> means that the only runnable |
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406 | coroutine is the currently running one, so C<cede> would have no effect, |
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407 | and C<schedule> would cause a deadlock unless there is an idle handler |
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408 | that wakes up some coroutines. |
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409 | |
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410 | =item my $guard = Coro::guard { ... } |
|
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411 | |
|
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412 | This creates and returns a guard object. Nothing happens until the objetc |
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413 | gets destroyed, in which case the codeblock given as argument will be |
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414 | executed. This is useful to free locks or other resources in case of a |
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415 | runtime error or when the coroutine gets canceled, as in both cases the |
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416 | guard block will be executed. The guard object supports only one method, |
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417 | C<< ->cancel >>, which will keep the codeblock from being executed. |
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418 | |
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419 | Example: set some flag and clear it again when the coroutine gets canceled |
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420 | or the function returns: |
|
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421 | |
|
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422 | sub do_something { |
|
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423 | my $guard = Coro::guard { $busy = 0 }; |
|
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424 | $busy = 1; |
|
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425 | |
|
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426 | # do something that requires $busy to be true |
|
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427 | } |
|
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428 | |
|
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429 | =cut |
|
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430 | |
|
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431 | sub guard(&) { |
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432 | bless \(my $cb = $_[0]), "Coro::guard" |
|
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433 | } |
|
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434 | |
|
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435 | sub Coro::guard::cancel { |
|
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436 | ${$_[0]} = sub { }; |
|
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437 | } |
|
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438 | |
|
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439 | sub Coro::guard::DESTROY { |
|
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440 | ${$_[0]}->(); |
|
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441 | } |
|
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442 | |
| 357 | |
443 | |
| 358 | =item unblock_sub { ... } |
444 | =item unblock_sub { ... } |
| 359 | |
445 | |
| 360 | This utility function takes a BLOCK or code reference and "unblocks" it, |
446 | 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 |
447 | returning the new coderef. This means that the new coderef will return |
