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11 print "2\n"; 11 print "2\n";
12 cede; # yield back to main 12 cede; # yield back to main
13 print "4\n"; 13 print "4\n";
14 }; 14 };
15 print "1\n"; 15 print "1\n";
16 cede; # yield to coroutine 16 cede; # yield to coro
17 print "3\n"; 17 print "3\n";
18 cede; # and again 18 cede; # and again
19 19
20 # use locking 20 # use locking
21 use Coro::Semaphore; 21 use Coro::Semaphore;
29=head1 DESCRIPTION 29=head1 DESCRIPTION
30 30
31For a tutorial-style introduction, please read the L<Coro::Intro> 31For a tutorial-style introduction, please read the L<Coro::Intro>
32manpage. This manpage mainly contains reference information. 32manpage. This manpage mainly contains reference information.
33 33
34This module collection manages continuations in general, most often 34This module collection manages continuations in general, most often in
35in the form of cooperative threads (also called coroutines in the 35the form of cooperative threads (also called coros, or simply "coro"
36documentation). They are similar to kernel threads but don't (in general) 36in the documentation). They are similar to kernel threads but don't (in
37run in parallel at the same time even on SMP machines. The specific flavor 37general) run in parallel at the same time even on SMP machines. The
38of thread offered by this module also guarantees you that it will not 38specific flavor of thread offered by this module also guarantees you that
39switch between threads unless necessary, at easily-identified points in 39it will not switch between threads unless necessary, at easily-identified
40your program, so locking and parallel access are rarely an issue, making 40points in your program, so locking and parallel access are rarely an
41thread programming much safer and easier than using other thread models. 41issue, making thread programming much safer and easier than using other
42thread models.
42 43
43Unlike the so-called "Perl threads" (which are not actually real threads 44Unlike the so-called "Perl threads" (which are not actually real threads
44but only the windows process emulation ported to unix), Coro provides a 45but only the windows process emulation ported to unix), Coro provides a
45full shared address space, which makes communication between threads 46full shared address space, which makes communication between threads
46very easy. And threads are fast, too: disabling the Windows process 47very easy. And threads are fast, too: disabling the Windows process
66package Coro; 67package Coro;
67 68
68use strict qw(vars subs); 69use strict qw(vars subs);
69no warnings "uninitialized"; 70no warnings "uninitialized";
70 71
72use Guard ();
73
71use Coro::State; 74use Coro::State;
72 75
73use base qw(Coro::State Exporter); 76use base qw(Coro::State Exporter);
74 77
75our $idle; # idle handler 78our $idle; # idle handler
76our $main; # main coroutine 79our $main; # main coro
77our $current; # current coroutine 80our $current; # current coro
78 81
79our $VERSION = 5.13; 82our $VERSION = 5.13;
80 83
81our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); 84our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
82our %EXPORT_TAGS = ( 85our %EXPORT_TAGS = (
88 91
89=over 4 92=over 4
90 93
91=item $Coro::main 94=item $Coro::main
92 95
93This variable stores the coroutine object that represents the main 96This variable stores the Coro object that represents the main
94program. While you cna C<ready> it and do most other things you can do to 97program. While you cna C<ready> it and do most other things you can do to
95coroutines, it is mainly useful to compare again C<$Coro::current>, to see 98coro, it is mainly useful to compare again C<$Coro::current>, to see
96whether you are running in the main program or not. 99whether you are running in the main program or not.
97 100
98=cut 101=cut
99 102
100# $main is now being initialised by Coro::State 103# $main is now being initialised by Coro::State
101 104
102=item $Coro::current 105=item $Coro::current
103 106
104The coroutine object representing the current coroutine (the last 107The Coro object representing the current coro (the last
105coroutine that the Coro scheduler switched to). The initial value is 108coro that the Coro scheduler switched to). The initial value is
106C<$Coro::main> (of course). 109C<$Coro::main> (of course).
107 110
108This variable is B<strictly> I<read-only>. You can take copies of the 111This variable is B<strictly> I<read-only>. You can take copies of the
109value stored in it and use it as any other coroutine object, but you must 112value stored in it and use it as any other Coro object, but you must
110not otherwise modify the variable itself. 113not otherwise modify the variable itself.
111 114
112=cut 115=cut
113 116
114sub current() { $current } # [DEPRECATED] 117sub current() { $current } # [DEPRECATED]
117 120
118This variable is mainly useful to integrate Coro into event loops. It is 121This variable is mainly useful to integrate Coro into event loops. It is
119usually better to rely on L<Coro::AnyEvent> or L<Coro::EV>, as this is 122usually better to rely on L<Coro::AnyEvent> or L<Coro::EV>, as this is
120pretty low-level functionality. 123pretty low-level functionality.
121 124
122This variable stores either a coroutine or a callback. 125This variable stores either a Coro object or a callback.
123 126
124If it is a callback, the it is called whenever the scheduler finds no 127If it is a callback, the it is called whenever the scheduler finds no
125ready coroutines to run. The default implementation prints "FATAL: 128ready coros to run. The default implementation prints "FATAL:
126deadlock detected" and exits, because the program has no other way to 129deadlock detected" and exits, because the program has no other way to
127continue. 130continue.
128 131
129If it is a coroutine object, then this object will be readied (without 132If it is a coro object, then this object will be readied (without
130invoking any ready hooks, however) when the scheduler finds no other ready 133invoking any ready hooks, however) when the scheduler finds no other ready
131coroutines to run. 134coros to run.
132 135
133This hook is overwritten by modules such as C<Coro::EV> and 136This hook is overwritten by modules such as C<Coro::EV> and
134C<Coro::AnyEvent> to wait on an external event that hopefully wake up a 137C<Coro::AnyEvent> to wait on an external event that hopefully wake up a
135coroutine so the scheduler can run it. 138coro so the scheduler can run it.
136 139
137Note that the callback I<must not>, under any circumstances, block 140Note that the callback I<must not>, under any circumstances, block
138the current coroutine. Normally, this is achieved by having an "idle 141the current coro. Normally, this is achieved by having an "idle
139coroutine" that calls the event loop and then blocks again, and then 142coro" that calls the event loop and then blocks again, and then
140readying that coroutine in the idle handler, or by simply placing the idle 143readying that coro in the idle handler, or by simply placing the idle
141coroutine in this variable. 144coro in this variable.
142 145
143See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this 146See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this
144technique. 147technique.
145 148
146Please note that if your callback recursively invokes perl (e.g. for event 149Please note that if your callback recursively invokes perl (e.g. for event
151$idle = sub { 154$idle = sub {
152 require Carp; 155 require Carp;
153 Carp::croak ("FATAL: deadlock detected"); 156 Carp::croak ("FATAL: deadlock detected");
154}; 157};
155 158
156# this coroutine is necessary because a coroutine 159# this coro is necessary because a coro
157# cannot destroy itself. 160# cannot destroy itself.
158our @destroy; 161our @destroy;
159our $manager; 162our $manager;
160 163
161$manager = new Coro sub { 164$manager = new Coro sub {
162 while () { 165 while () {
163 Coro::_cancel shift @destroy 166 Coro::State::cancel shift @destroy
164 while @destroy; 167 while @destroy;
165 168
166 &schedule; 169 &schedule;
167 } 170 }
168}; 171};
169$manager->{desc} = "[coro manager]"; 172$manager->{desc} = "[coro manager]";
170$manager->prio (PRIO_MAX); 173$manager->prio (PRIO_MAX);
171 174
172=back 175=back
173 176
174=head1 SIMPLE COROUTINE CREATION 177=head1 SIMPLE CORO CREATION
175 178
176=over 4 179=over 4
177 180
178=item async { ... } [@args...] 181=item async { ... } [@args...]
179 182
180Create a new coroutine and return its coroutine object (usually 183Create a new coro and return its Coro object (usually
181unused). The coroutine will be put into the ready queue, so 184unused). The coro will be put into the ready queue, so
182it will start running automatically on the next scheduler run. 185it will start running automatically on the next scheduler run.
183 186
184The first argument is a codeblock/closure that should be executed in the 187The first argument is a codeblock/closure that should be executed in the
185coroutine. When it returns argument returns the coroutine is automatically 188coro. When it returns argument returns the coro is automatically
186terminated. 189terminated.
187 190
188The remaining arguments are passed as arguments to the closure. 191The remaining arguments are passed as arguments to the closure.
189 192
190See the C<Coro::State::new> constructor for info about the coroutine 193See the C<Coro::State::new> constructor for info about the coro
191environment in which coroutines are executed. 194environment in which coro are executed.
192 195
193Calling C<exit> in a coroutine will do the same as calling exit outside 196Calling C<exit> in a coro will do the same as calling exit outside
194the coroutine. Likewise, when the coroutine dies, the program will exit, 197the coro. Likewise, when the coro dies, the program will exit,
195just as it would in the main program. 198just as it would in the main program.
196 199
197If you do not want that, you can provide a default C<die> handler, or 200If you do not want that, you can provide a default C<die> handler, or
198simply avoid dieing (by use of C<eval>). 201simply avoid dieing (by use of C<eval>).
199 202
200Example: Create a new coroutine that just prints its arguments. 203Example: Create a new coro that just prints its arguments.
201 204
202 async { 205 async {
203 print "@_\n"; 206 print "@_\n";
204 } 1,2,3,4; 207 } 1,2,3,4;
205 208
211 $coro 214 $coro
212} 215}
213 216
214=item async_pool { ... } [@args...] 217=item async_pool { ... } [@args...]
215 218
216Similar to C<async>, but uses a coroutine pool, so you should not call 219Similar to C<async>, but uses a coro pool, so you should not call
217terminate or join on it (although you are allowed to), and you get a 220terminate or join on it (although you are allowed to), and you get a
218coroutine that might have executed other code already (which can be good 221coro that might have executed other code already (which can be good
219or bad :). 222or bad :).
220 223
221On the plus side, this function is about twice as fast as creating (and 224On the plus side, this function is about twice as fast as creating (and
222destroying) a completely new coroutine, so if you need a lot of generic 225destroying) a completely new coro, so if you need a lot of generic
223coroutines in quick successsion, use C<async_pool>, not C<async>. 226coros in quick successsion, use C<async_pool>, not C<async>.
224 227
225The code block is executed in an C<eval> context and a warning will be 228The code block is executed in an C<eval> context and a warning will be
226issued in case of an exception instead of terminating the program, as 229issued in case of an exception instead of terminating the program, as
227C<async> does. As the coroutine is being reused, stuff like C<on_destroy> 230C<async> does. As the coro is being reused, stuff like C<on_destroy>
228will not work in the expected way, unless you call terminate or cancel, 231will not work in the expected way, unless you call terminate or cancel,
229which somehow defeats the purpose of pooling (but is fine in the 232which somehow defeats the purpose of pooling (but is fine in the
230exceptional case). 233exceptional case).
231 234
232The priority will be reset to C<0> after each run, tracing will be 235The priority will be reset to C<0> after each run, tracing will be
233disabled, the description will be reset and the default output filehandle 236disabled, the description will be reset and the default output filehandle
234gets restored, so you can change all these. Otherwise the coroutine will 237gets restored, so you can change all these. Otherwise the coro will
235be re-used "as-is": most notably if you change other per-coroutine global 238be re-used "as-is": most notably if you change other per-coro global
236stuff such as C<$/> you I<must needs> revert that change, which is most 239stuff such as C<$/> you I<must needs> revert that change, which is most
237simply done by using local as in: C<< local $/ >>. 240simply done by using local as in: C<< local $/ >>.
238 241
239The idle pool size is limited to C<8> idle coroutines (this can be 242The idle pool size is limited to C<8> idle coros (this can be
240adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle 243adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle
241coros as required. 244coros as required.
242 245
243If you are concerned about pooled coroutines growing a lot because a 246If you are concerned about pooled coros growing a lot because a
244single C<async_pool> used a lot of stackspace you can e.g. C<async_pool 247single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
245{ terminate }> once per second or so to slowly replenish the pool. In 248{ terminate }> once per second or so to slowly replenish the pool. In
246addition to that, when the stacks used by a handler grows larger than 32kb 249addition to that, when the stacks used by a handler grows larger than 32kb
247(adjustable via $Coro::POOL_RSS) it will also be destroyed. 250(adjustable via $Coro::POOL_RSS) it will also be destroyed.
248 251
265=back 268=back
266 269
267=head1 STATIC METHODS 270=head1 STATIC METHODS
268 271
269Static methods are actually functions that implicitly operate on the 272Static methods are actually functions that implicitly operate on the
270current coroutine. 273current coro.
271 274
272=over 4 275=over 4
273 276
274=item schedule 277=item schedule
275 278
276Calls the scheduler. The scheduler will find the next coroutine that is 279Calls the scheduler. The scheduler will find the next coro that is
277to be run from the ready queue and switches to it. The next coroutine 280to be run from the ready queue and switches to it. The next coro
278to be run is simply the one with the highest priority that is longest 281to be run is simply the one with the highest priority that is longest
279in its ready queue. If there is no coroutine ready, it will clal the 282in its ready queue. If there is no coro ready, it will clal the
280C<$Coro::idle> hook. 283C<$Coro::idle> hook.
281 284
282Please note that the current coroutine will I<not> be put into the ready 285Please note that the current coro will I<not> be put into the ready
283queue, so calling this function usually means you will never be called 286queue, so calling this function usually means you will never be called
284again unless something else (e.g. an event handler) calls C<< ->ready >>, 287again unless something else (e.g. an event handler) calls C<< ->ready >>,
285thus waking you up. 288thus waking you up.
286 289
287This makes C<schedule> I<the> generic method to use to block the current 290This makes C<schedule> I<the> generic method to use to block the current
288coroutine and wait for events: first you remember the current coroutine in 291coro and wait for events: first you remember the current coro in
289a variable, then arrange for some callback of yours to call C<< ->ready 292a variable, then arrange for some callback of yours to call C<< ->ready
290>> on that once some event happens, and last you call C<schedule> to put 293>> on that once some event happens, and last you call C<schedule> to put
291yourself to sleep. Note that a lot of things can wake your coroutine up, 294yourself to sleep. Note that a lot of things can wake your coro up,
292so you need to check whether the event indeed happened, e.g. by storing the 295so you need to check whether the event indeed happened, e.g. by storing the
293status in a variable. 296status in a variable.
294 297
295See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks. 298See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks.
296 299
297=item cede 300=item cede
298 301
299"Cede" to other coroutines. This function puts the current coroutine into 302"Cede" to other coros. This function puts the current coro into
300the ready queue and calls C<schedule>, which has the effect of giving 303the ready queue and calls C<schedule>, which has the effect of giving
301up the current "timeslice" to other coroutines of the same or higher 304up the current "timeslice" to other coros of the same or higher
302priority. Once your coroutine gets its turn again it will automatically be 305priority. Once your coro gets its turn again it will automatically be
303resumed. 306resumed.
304 307
305This function is often called C<yield> in other languages. 308This function is often called C<yield> in other languages.
306 309
307=item Coro::cede_notself 310=item Coro::cede_notself
308 311
309Works like cede, but is not exported by default and will cede to I<any> 312Works like cede, but is not exported by default and will cede to I<any>
310coroutine, regardless of priority. This is useful sometimes to ensure 313coro, regardless of priority. This is useful sometimes to ensure
311progress is made. 314progress is made.
312 315
313=item terminate [arg...] 316=item terminate [arg...]
314 317
315Terminates the current coroutine with the given status values (see L<cancel>). 318Terminates the current coro with the given status values (see L<cancel>).
319
320=item Coro::on_enter BLOCK, Coro::on_leave BLOCK
321
322These function install enter and leave winders in the current scope. The
323enter block will be executed when on_enter is called and whenever the
324current coro is re-entered by the scheduler, while the leave block is
325executed whenever the current coro is blocked by the scheduler, and
326also when the containing scope is exited (by whatever means, be it exit,
327die, last etc.).
328
329I<Neither invoking the scheduler, nor exceptions, are allowed within those
330BLOCKs>. That means: do not even think about calling C<die> without an
331eval, and do not even think of entering the scheduler in any way.
332
333Since both BLOCKs are tied to the current scope, they will automatically
334be removed when the current scope exits.
335
336These functions implement the same concept as C<dynamic-wind> in scheme
337does, and are useful when you want to localise some resource to a specific
338coro.
339
340They slow down coro switching considerably for coros that use
341them (But coro switching is still reasonably fast if the handlers are
342fast).
343
344These functions are best understood by an example: The following function
345will change the current timezone to "Antarctica/South_Pole", which
346requires a call to C<tzset>, but by using C<on_enter> and C<on_leave>,
347which remember/change the current timezone and restore the previous
348value, respectively, the timezone is only changes for the coro that
349installed those handlers.
350
351 use POSIX qw(tzset);
352
353 async {
354 my $old_tz; # store outside TZ value here
355
356 Coro::on_enter {
357 $old_tz = $ENV{TZ}; # remember the old value
358
359 $ENV{TZ} = "Antarctica/South_Pole";
360 tzset; # enable new value
361 };
362
363 Coro::on_leave {
364 $ENV{TZ} = $old_tz;
365 tzset; # restore old value
366 };
367
368 # at this place, the timezone is Antarctica/South_Pole,
369 # without disturbing the TZ of any other coro.
370 };
371
372This can be used to localise about any resource (locale, uid, current
373working directory etc.) to a block, despite the existance of other
374coros.
316 375
317=item killall 376=item killall
318 377
319Kills/terminates/cancels all coroutines except the currently running 378Kills/terminates/cancels all coros except the currently running one.
320one. This can be useful after a fork, either in the child or the parent,
321as usually only one of them should inherit the running coroutines.
322 379
323Note that in the implementation, destructors run as normal, making this
324function not so useful after a fork. Future versions of this function
325might try to free resources without running any code.
326
327Note that while this will try to free some of the main programs resources, 380Note that while this will try to free some of the main interpreter
381resources if the calling coro isn't the main coro, but one
328you cannot free all of them, so if a coroutine that is not the main 382cannot free all of them, so if a coro that is not the main coro
329program calls this function, there will be some one-time resource leak. 383calls this function, there will be some one-time resource leak.
330 384
331=cut 385=cut
332 386
333sub killall { 387sub killall {
334 for (Coro::State::list) { 388 for (Coro::State::list) {
337 } 391 }
338} 392}
339 393
340=back 394=back
341 395
342=head1 COROUTINE OBJECT METHODS 396=head1 CORO OBJECT METHODS
343 397
344These are the methods you can call on coroutine objects (or to create 398These are the methods you can call on coro objects (or to create
345them). 399them).
346 400
347=over 4 401=over 4
348 402
349=item new Coro \&sub [, @args...] 403=item new Coro \&sub [, @args...]
350 404
351Create a new coroutine and return it. When the sub returns, the coroutine 405Create a new coro and return it. When the sub returns, the coro
352automatically terminates as if C<terminate> with the returned values were 406automatically terminates as if C<terminate> with the returned values were
353called. To make the coroutine run you must first put it into the ready 407called. To make the coro run you must first put it into the ready
354queue by calling the ready method. 408queue by calling the ready method.
355 409
356See C<async> and C<Coro::State::new> for additional info about the 410See C<async> and C<Coro::State::new> for additional info about the
357coroutine environment. 411coro environment.
358 412
359=cut 413=cut
360 414
361sub _coro_run { 415sub _coro_run {
362 terminate &{+shift}; 416 terminate &{+shift};
363} 417}
364 418
365=item $success = $coroutine->ready 419=item $success = $coro->ready
366 420
367Put the given coroutine into the end of its ready queue (there is one 421Put the given coro into the end of its ready queue (there is one
368queue for each priority) and return true. If the coroutine is already in 422queue for each priority) and return true. If the coro is already in
369the ready queue, do nothing and return false. 423the ready queue, do nothing and return false.
370 424
371This ensures that the scheduler will resume this coroutine automatically 425This ensures that the scheduler will resume this coro automatically
372once all the coroutines of higher priority and all coroutines of the same 426once all the coro of higher priority and all coro of the same
373priority that were put into the ready queue earlier have been resumed. 427priority that were put into the ready queue earlier have been resumed.
374 428
375=item $is_ready = $coroutine->is_ready 429=item $is_ready = $coro->is_ready
376 430
377Return whether the coroutine is currently the ready queue or not, 431Returns true iff the Coro object is in the ready queue. Unless the Coro
432object gets destroyed, it will eventually be scheduled by the scheduler.
378 433
434=item $is_running = $coro->is_running
435
436Returns true iff the Coro object is currently running. Only one Coro object
437can ever be in the running state (but it currently is possible to have
438multiple running Coro::States).
439
440=item $is_suspended = $coro->is_suspended
441
442Returns true iff this Coro object has been suspended. Suspended Coros will
443not ever be scheduled.
444
379=item $coroutine->cancel (arg...) 445=item $coro->cancel (arg...)
380 446
381Terminates the given coroutine and makes it return the given arguments as 447Terminates the given Coro and makes it return the given arguments as
382status (default: the empty list). Never returns if the coroutine is the 448status (default: the empty list). Never returns if the Coro is the
383current coroutine. 449current Coro.
384 450
385=cut 451=cut
386 452
387sub cancel { 453sub cancel {
388 my $self = shift; 454 my $self = shift;
389 455
390 if ($current == $self) { 456 if ($current == $self) {
391 terminate @_; 457 terminate @_;
392 } else { 458 } else {
393 $self->{_status} = [@_]; 459 $self->{_status} = [@_];
394 $self->_cancel; 460 Coro::State::cancel $self;
395 } 461 }
396} 462}
397 463
398=item $coroutine->schedule_to 464=item $coro->schedule_to
399 465
400Puts the current coroutine to sleep (like C<Coro::schedule>), but instead 466Puts the current coro to sleep (like C<Coro::schedule>), but instead
401of continuing with the next coro from the ready queue, always switch to 467of continuing with the next coro from the ready queue, always switch to
402the given coroutine object (regardless of priority etc.). The readyness 468the given coro object (regardless of priority etc.). The readyness
403state of that coroutine isn't changed. 469state of that coro isn't changed.
404 470
405This is an advanced method for special cases - I'd love to hear about any 471This is an advanced method for special cases - I'd love to hear about any
406uses for this one. 472uses for this one.
407 473
408=item $coroutine->cede_to 474=item $coro->cede_to
409 475
410Like C<schedule_to>, but puts the current coroutine into the ready 476Like C<schedule_to>, but puts the current coro into the ready
411queue. This has the effect of temporarily switching to the given 477queue. This has the effect of temporarily switching to the given
412coroutine, and continuing some time later. 478coro, and continuing some time later.
413 479
414This is an advanced method for special cases - I'd love to hear about any 480This is an advanced method for special cases - I'd love to hear about any
415uses for this one. 481uses for this one.
416 482
417=item $coroutine->throw ([$scalar]) 483=item $coro->throw ([$scalar])
418 484
419If C<$throw> is specified and defined, it will be thrown as an exception 485If C<$throw> is specified and defined, it will be thrown as an exception
420inside the coroutine at the next convenient point in time. Otherwise 486inside the coro at the next convenient point in time. Otherwise
421clears the exception object. 487clears the exception object.
422 488
423Coro will check for the exception each time a schedule-like-function 489Coro will check for the exception each time a schedule-like-function
424returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down 490returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down
425>>, C<< Coro::Handle->readable >> and so on. Most of these functions 491>>, C<< Coro::Handle->readable >> and so on. Most of these functions
427 493
428The exception object will be thrown "as is" with the specified scalar in 494The exception object will be thrown "as is" with the specified scalar in
429C<$@>, i.e. if it is a string, no line number or newline will be appended 495C<$@>, i.e. if it is a string, no line number or newline will be appended
430(unlike with C<die>). 496(unlike with C<die>).
431 497
432This can be used as a softer means than C<cancel> to ask a coroutine to 498This can be used as a softer means than C<cancel> to ask a coro to
433end itself, although there is no guarantee that the exception will lead to 499end itself, although there is no guarantee that the exception will lead to
434termination, and if the exception isn't caught it might well end the whole 500termination, and if the exception isn't caught it might well end the whole
435program. 501program.
436 502
437You might also think of C<throw> as being the moral equivalent of 503You might also think of C<throw> as being the moral equivalent of
438C<kill>ing a coroutine with a signal (in this case, a scalar). 504C<kill>ing a coro with a signal (in this case, a scalar).
439 505
440=item $coroutine->join 506=item $coro->join
441 507
442Wait until the coroutine terminates and return any values given to the 508Wait until the coro terminates and return any values given to the
443C<terminate> or C<cancel> functions. C<join> can be called concurrently 509C<terminate> or C<cancel> functions. C<join> can be called concurrently
444from multiple coroutines, and all will be resumed and given the status 510from multiple coro, and all will be resumed and given the status
445return once the C<$coroutine> terminates. 511return once the C<$coro> terminates.
446 512
447=cut 513=cut
448 514
449sub join { 515sub join {
450 my $self = shift; 516 my $self = shift;
461 } 527 }
462 528
463 wantarray ? @{$self->{_status}} : $self->{_status}[0]; 529 wantarray ? @{$self->{_status}} : $self->{_status}[0];
464} 530}
465 531
466=item $coroutine->on_destroy (\&cb) 532=item $coro->on_destroy (\&cb)
467 533
468Registers a callback that is called when this coroutine gets destroyed, 534Registers a callback that is called when this coro gets destroyed,
469but before it is joined. The callback gets passed the terminate arguments, 535but before it is joined. The callback gets passed the terminate arguments,
470if any, and I<must not> die, under any circumstances. 536if any, and I<must not> die, under any circumstances.
471 537
472=cut 538=cut
473 539
475 my ($self, $cb) = @_; 541 my ($self, $cb) = @_;
476 542
477 push @{ $self->{_on_destroy} }, $cb; 543 push @{ $self->{_on_destroy} }, $cb;
478} 544}
479 545
480=item $oldprio = $coroutine->prio ($newprio) 546=item $oldprio = $coro->prio ($newprio)
481 547
482Sets (or gets, if the argument is missing) the priority of the 548Sets (or gets, if the argument is missing) the priority of the
483coroutine. Higher priority coroutines get run before lower priority 549coro. Higher priority coro get run before lower priority
484coroutines. Priorities are small signed integers (currently -4 .. +3), 550coro. Priorities are small signed integers (currently -4 .. +3),
485that you can refer to using PRIO_xxx constants (use the import tag :prio 551that you can refer to using PRIO_xxx constants (use the import tag :prio
486to get then): 552to get then):
487 553
488 PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN 554 PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
489 3 > 1 > 0 > -1 > -3 > -4 555 3 > 1 > 0 > -1 > -3 > -4
490 556
491 # set priority to HIGH 557 # set priority to HIGH
492 current->prio(PRIO_HIGH); 558 current->prio (PRIO_HIGH);
493 559
494The idle coroutine ($Coro::idle) always has a lower priority than any 560The idle coro ($Coro::idle) always has a lower priority than any
495existing coroutine. 561existing coro.
496 562
497Changing the priority of the current coroutine will take effect immediately, 563Changing the priority of the current coro will take effect immediately,
498but changing the priority of coroutines in the ready queue (but not 564but changing the priority of coro in the ready queue (but not
499running) will only take effect after the next schedule (of that 565running) will only take effect after the next schedule (of that
500coroutine). This is a bug that will be fixed in some future version. 566coro). This is a bug that will be fixed in some future version.
501 567
502=item $newprio = $coroutine->nice ($change) 568=item $newprio = $coro->nice ($change)
503 569
504Similar to C<prio>, but subtract the given value from the priority (i.e. 570Similar to C<prio>, but subtract the given value from the priority (i.e.
505higher values mean lower priority, just as in unix). 571higher values mean lower priority, just as in unix).
506 572
507=item $olddesc = $coroutine->desc ($newdesc) 573=item $olddesc = $coro->desc ($newdesc)
508 574
509Sets (or gets in case the argument is missing) the description for this 575Sets (or gets in case the argument is missing) the description for this
510coroutine. This is just a free-form string you can associate with a 576coro. This is just a free-form string you can associate with a
511coroutine. 577coro.
512 578
513This method simply sets the C<< $coroutine->{desc} >> member to the given 579This method simply sets the C<< $coro->{desc} >> member to the given
514string. You can modify this member directly if you wish. 580string. You can modify this member directly if you wish.
515 581
516=cut 582=cut
517 583
518sub desc { 584sub desc {
532 598
533=over 4 599=over 4
534 600
535=item Coro::nready 601=item Coro::nready
536 602
537Returns the number of coroutines that are currently in the ready state, 603Returns the number of coro that are currently in the ready state,
538i.e. that can be switched to by calling C<schedule> directory or 604i.e. that can be switched to by calling C<schedule> directory or
539indirectly. The value C<0> means that the only runnable coroutine is the 605indirectly. The value C<0> means that the only runnable coro is the
540currently running one, so C<cede> would have no effect, and C<schedule> 606currently running one, so C<cede> would have no effect, and C<schedule>
541would cause a deadlock unless there is an idle handler that wakes up some 607would cause a deadlock unless there is an idle handler that wakes up some
542coroutines. 608coro.
543 609
544=item my $guard = Coro::guard { ... } 610=item my $guard = Coro::guard { ... }
545 611
546This function still exists, but is deprecated. Please use the 612This function still exists, but is deprecated. Please use the
547C<Guard::guard> function instead. 613C<Guard::guard> function instead.
554 620
555This utility function takes a BLOCK or code reference and "unblocks" it, 621This utility function takes a BLOCK or code reference and "unblocks" it,
556returning a new coderef. Unblocking means that calling the new coderef 622returning a new coderef. Unblocking means that calling the new coderef
557will return immediately without blocking, returning nothing, while the 623will return immediately without blocking, returning nothing, while the
558original code ref will be called (with parameters) from within another 624original code ref will be called (with parameters) from within another
559coroutine. 625coro.
560 626
561The reason this function exists is that many event libraries (such as the 627The reason this function exists is that many event libraries (such as the
562venerable L<Event|Event> module) are not coroutine-safe (a weaker form 628venerable L<Event|Event> module) are not thread-safe (a weaker form
563of reentrancy). This means you must not block within event callbacks, 629of reentrancy). This means you must not block within event callbacks,
564otherwise you might suffer from crashes or worse. The only event library 630otherwise you might suffer from crashes or worse. The only event library
565currently known that is safe to use without C<unblock_sub> is L<EV>. 631currently known that is safe to use without C<unblock_sub> is L<EV>.
566 632
567This function allows your callbacks to block by executing them in another 633This function allows your callbacks to block by executing them in another
568coroutine where it is safe to block. One example where blocking is handy 634coro where it is safe to block. One example where blocking is handy
569is when you use the L<Coro::AIO|Coro::AIO> functions to save results to 635is when you use the L<Coro::AIO|Coro::AIO> functions to save results to
570disk, for example. 636disk, for example.
571 637
572In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when 638In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
573creating event callbacks that want to block. 639creating event callbacks that want to block.
574 640
575If your handler does not plan to block (e.g. simply sends a message to 641If your handler does not plan to block (e.g. simply sends a message to
576another coroutine, or puts some other coroutine into the ready queue), 642another coro, or puts some other coro into the ready queue), there is
577there is no reason to use C<unblock_sub>. 643no reason to use C<unblock_sub>.
578 644
579Note that you also need to use C<unblock_sub> for any other callbacks that 645Note that you also need to use C<unblock_sub> for any other callbacks that
580are indirectly executed by any C-based event loop. For example, when you 646are indirectly executed by any C-based event loop. For example, when you
581use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it 647use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it
582provides callbacks that are the result of some event callback, then you 648provides callbacks that are the result of some event callback, then you
616 682
617=item $cb = Coro::rouse_cb 683=item $cb = Coro::rouse_cb
618 684
619Create and return a "rouse callback". That's a code reference that, 685Create and return a "rouse callback". That's a code reference that,
620when called, will remember a copy of its arguments and notify the owner 686when called, will remember a copy of its arguments and notify the owner
621coroutine of the callback. 687coro of the callback.
622 688
623See the next function. 689See the next function.
624 690
625=item @args = Coro::rouse_wait [$cb] 691=item @args = Coro::rouse_wait [$cb]
626 692
627Wait for the specified rouse callback (or the last one that was created in 693Wait for the specified rouse callback (or the last one that was created in
628this coroutine). 694this coro).
629 695
630As soon as the callback is invoked (or when the callback was invoked 696As soon as the callback is invoked (or when the callback was invoked
631before C<rouse_wait>), it will return the arguments originally passed to 697before C<rouse_wait>), it will return the arguments originally passed to
632the rouse callback. 698the rouse callback.
633 699
639 705
6401; 7061;
641 707
642=head1 HOW TO WAIT FOR A CALLBACK 708=head1 HOW TO WAIT FOR A CALLBACK
643 709
644It is very common for a coroutine to wait for some callback to be 710It is very common for a coro to wait for some callback to be
645called. This occurs naturally when you use coroutines in an otherwise 711called. This occurs naturally when you use coro in an otherwise
646event-based program, or when you use event-based libraries. 712event-based program, or when you use event-based libraries.
647 713
648These typically register a callback for some event, and call that callback 714These typically register a callback for some event, and call that callback
649when the event occured. In a coroutine, however, you typically want to 715when the event occured. In a coro, however, you typically want to
650just wait for the event, simplyifying things. 716just wait for the event, simplyifying things.
651 717
652For example C<< AnyEvent->child >> registers a callback to be called when 718For example C<< AnyEvent->child >> registers a callback to be called when
653a specific child has exited: 719a specific child has exited:
654 720
655 my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... }); 721 my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... });
656 722
657But from withina coroutine, you often just want to write this: 723But from within a coro, you often just want to write this:
658 724
659 my $status = wait_for_child $pid; 725 my $status = wait_for_child $pid;
660 726
661Coro offers two functions specifically designed to make this easy, 727Coro offers two functions specifically designed to make this easy,
662C<Coro::rouse_cb> and C<Coro::rouse_wait>. 728C<Coro::rouse_cb> and C<Coro::rouse_wait>.
663 729
664The first function, C<rouse_cb>, generates and returns a callback that, 730The first function, C<rouse_cb>, generates and returns a callback that,
665when invoked, will save its arguments and notify the coroutine that 731when invoked, will save its arguments and notify the coro that
666created the callback. 732created the callback.
667 733
668The second function, C<rouse_wait>, waits for the callback to be called 734The second function, C<rouse_wait>, waits for the callback to be called
669(by calling C<schedule> to go to sleep) and returns the arguments 735(by calling C<schedule> to go to sleep) and returns the arguments
670originally passed to the callback. 736originally passed to the callback.
685you can roll your own, using C<schedule>: 751you can roll your own, using C<schedule>:
686 752
687 sub wait_for_child($) { 753 sub wait_for_child($) {
688 my ($pid) = @_; 754 my ($pid) = @_;
689 755
690 # store the current coroutine in $current, 756 # store the current coro in $current,
691 # and provide result variables for the closure passed to ->child 757 # and provide result variables for the closure passed to ->child
692 my $current = $Coro::current; 758 my $current = $Coro::current;
693 my ($done, $rstatus); 759 my ($done, $rstatus);
694 760
695 # pass a closure to ->child 761 # pass a closure to ->child
711 777
712=item fork with pthread backend 778=item fork with pthread backend
713 779
714When Coro is compiled using the pthread backend (which isn't recommended 780When Coro is compiled using the pthread backend (which isn't recommended
715but required on many BSDs as their libcs are completely broken), then 781but required on many BSDs as their libcs are completely broken), then
716coroutines will not survive a fork. There is no known workaround except to 782coro will not survive a fork. There is no known workaround except to
717fix your libc and use a saner backend. 783fix your libc and use a saner backend.
718 784
719=item perl process emulation ("threads") 785=item perl process emulation ("threads")
720 786
721This module is not perl-pseudo-thread-safe. You should only ever use this 787This module is not perl-pseudo-thread-safe. You should only ever use this
723future to allow per-thread schedulers, but Coro::State does not yet allow 789future to allow per-thread schedulers, but Coro::State does not yet allow
724this). I recommend disabling thread support and using processes, as having 790this). I recommend disabling thread support and using processes, as having
725the windows process emulation enabled under unix roughly halves perl 791the windows process emulation enabled under unix roughly halves perl
726performance, even when not used. 792performance, even when not used.
727 793
728=item coroutine switching not signal safe 794=item coro switching is not signal safe
729 795
730You must not switch to another coroutine from within a signal handler 796You must not switch to another coro from within a signal handler
731(only relevant with %SIG - most event libraries provide safe signals). 797(only relevant with %SIG - most event libraries provide safe signals).
732 798
733That means you I<MUST NOT> call any function that might "block" the 799That means you I<MUST NOT> call any function that might "block" the
734current coroutine - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or 800current coro - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or
735anything that calls those. Everything else, including calling C<ready>, 801anything that calls those. Everything else, including calling C<ready>,
736works. 802works.
737 803
738=back 804=back
739 805

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