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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, and as such act
45full shared address space, which makes communication between threads 46as processes), Coro provides a full shared address space, which makes
46very easy. And threads are fast, too: disabling the Windows process 47communication between threads very easy. And Coro's threads are fast,
47emulation code in your perl and using Coro can easily result in a two to 48too: disabling the Windows process emulation code in your perl and using
48four times speed increase for your programs. 49Coro can easily result in a two to four times speed increase for your
50programs. A parallel matrix multiplication benchmark runs over 300 times
51faster on a single core than perl's pseudo-threads on a quad core using
52all four cores.
49 53
50Coro achieves that by supporting multiple running interpreters that share 54Coro achieves that by supporting multiple running interpreters that share
51data, which is especially useful to code pseudo-parallel processes and 55data, which is especially useful to code pseudo-parallel processes and
52for event-based programming, such as multiple HTTP-GET requests running 56for event-based programming, such as multiple HTTP-GET requests running
53concurrently. See L<Coro::AnyEvent> to learn more on how to integrate Coro 57concurrently. See L<Coro::AnyEvent> to learn more on how to integrate Coro
54into an event-based environment. 58into an event-based environment.
55 59
56In this module, a thread is defined as "callchain + lexical variables + 60In this module, a thread is defined as "callchain + lexical variables +
57@_ + $_ + $@ + $/ + C stack), that is, a thread has its own callchain, 61some package variables + C stack), that is, a thread has its own callchain,
58its own set of lexicals and its own set of perls most important global 62its own set of lexicals and its own set of perls most important global
59variables (see L<Coro::State> for more configuration and background info). 63variables (see L<Coro::State> for more configuration and background info).
60 64
61See also the C<SEE ALSO> section at the end of this document - the Coro 65See also the C<SEE ALSO> section at the end of this document - the Coro
62module family is quite large. 66module family is quite large.
66package Coro; 70package Coro;
67 71
68use strict qw(vars subs); 72use strict qw(vars subs);
69no warnings "uninitialized"; 73no warnings "uninitialized";
70 74
75use Guard ();
76
71use Coro::State; 77use Coro::State;
72 78
73use base qw(Coro::State Exporter); 79use base qw(Coro::State Exporter);
74 80
75our $idle; # idle handler 81our $idle; # idle handler
76our $main; # main coroutine 82our $main; # main coro
77our $current; # current coroutine 83our $current; # current coro
78 84
79our $VERSION = 5.12; 85our $VERSION = 5.131;
80 86
81our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); 87our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
82our %EXPORT_TAGS = ( 88our %EXPORT_TAGS = (
83 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], 89 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
84); 90);
88 94
89=over 4 95=over 4
90 96
91=item $Coro::main 97=item $Coro::main
92 98
93This variable stores the coroutine object that represents the main 99This variable stores the Coro object that represents the main
94program. While you cna C<ready> it and do most other things you can do to 100program. While you cna C<ready> it and do most other things you can do to
95coroutines, it is mainly useful to compare again C<$Coro::current>, to see 101coro, it is mainly useful to compare again C<$Coro::current>, to see
96whether you are running in the main program or not. 102whether you are running in the main program or not.
97 103
98=cut 104=cut
99 105
100# $main is now being initialised by Coro::State 106# $main is now being initialised by Coro::State
101 107
102=item $Coro::current 108=item $Coro::current
103 109
104The coroutine object representing the current coroutine (the last 110The Coro object representing the current coro (the last
105coroutine that the Coro scheduler switched to). The initial value is 111coro that the Coro scheduler switched to). The initial value is
106C<$Coro::main> (of course). 112C<$Coro::main> (of course).
107 113
108This variable is B<strictly> I<read-only>. You can take copies of the 114This 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 115value stored in it and use it as any other Coro object, but you must
110not otherwise modify the variable itself. 116not otherwise modify the variable itself.
111 117
112=cut 118=cut
113 119
114sub current() { $current } # [DEPRECATED] 120sub current() { $current } # [DEPRECATED]
117 123
118This variable is mainly useful to integrate Coro into event loops. It is 124This 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 125usually better to rely on L<Coro::AnyEvent> or L<Coro::EV>, as this is
120pretty low-level functionality. 126pretty low-level functionality.
121 127
122This variable stores either a coroutine or a callback. 128This variable stores either a Coro object or a callback.
123 129
124If it is a callback, the it is called whenever the scheduler finds no 130If it is a callback, the it is called whenever the scheduler finds no
125ready coroutines to run. The default implementation prints "FATAL: 131ready coros to run. The default implementation prints "FATAL:
126deadlock detected" and exits, because the program has no other way to 132deadlock detected" and exits, because the program has no other way to
127continue. 133continue.
128 134
129If it is a coroutine object, then this object will be readied (without 135If it is a coro object, then this object will be readied (without
130invoking any ready hooks, however) when the scheduler finds no other ready 136invoking any ready hooks, however) when the scheduler finds no other ready
131coroutines to run. 137coros to run.
132 138
133This hook is overwritten by modules such as C<Coro::EV> and 139This 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 140C<Coro::AnyEvent> to wait on an external event that hopefully wake up a
135coroutine so the scheduler can run it. 141coro so the scheduler can run it.
136 142
137Note that the callback I<must not>, under any circumstances, block 143Note that the callback I<must not>, under any circumstances, block
138the current coroutine. Normally, this is achieved by having an "idle 144the current coro. Normally, this is achieved by having an "idle
139coroutine" that calls the event loop and then blocks again, and then 145coro" that calls the event loop and then blocks again, and then
140readying that coroutine in the idle handler, or by simply placing the idle 146readying that coro in the idle handler, or by simply placing the idle
141coroutine in this variable. 147coro in this variable.
142 148
143See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this 149See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this
144technique. 150technique.
145 151
146Please note that if your callback recursively invokes perl (e.g. for event 152Please note that if your callback recursively invokes perl (e.g. for event
151$idle = sub { 157$idle = sub {
152 require Carp; 158 require Carp;
153 Carp::croak ("FATAL: deadlock detected"); 159 Carp::croak ("FATAL: deadlock detected");
154}; 160};
155 161
156# this coroutine is necessary because a coroutine 162# this coro is necessary because a coro
157# cannot destroy itself. 163# cannot destroy itself.
158our @destroy; 164our @destroy;
159our $manager; 165our $manager;
160 166
161$manager = new Coro sub { 167$manager = new Coro sub {
162 while () { 168 while () {
163 Coro::_cancel shift @destroy 169 Coro::State::cancel shift @destroy
164 while @destroy; 170 while @destroy;
165 171
166 &schedule; 172 &schedule;
167 } 173 }
168}; 174};
169$manager->{desc} = "[coro manager]"; 175$manager->{desc} = "[coro manager]";
170$manager->prio (PRIO_MAX); 176$manager->prio (PRIO_MAX);
171 177
172=back 178=back
173 179
174=head1 SIMPLE COROUTINE CREATION 180=head1 SIMPLE CORO CREATION
175 181
176=over 4 182=over 4
177 183
178=item async { ... } [@args...] 184=item async { ... } [@args...]
179 185
180Create a new coroutine and return its coroutine object (usually 186Create a new coro and return its Coro object (usually
181unused). The coroutine will be put into the ready queue, so 187unused). The coro will be put into the ready queue, so
182it will start running automatically on the next scheduler run. 188it will start running automatically on the next scheduler run.
183 189
184The first argument is a codeblock/closure that should be executed in the 190The first argument is a codeblock/closure that should be executed in the
185coroutine. When it returns argument returns the coroutine is automatically 191coro. When it returns argument returns the coro is automatically
186terminated. 192terminated.
187 193
188The remaining arguments are passed as arguments to the closure. 194The remaining arguments are passed as arguments to the closure.
189 195
190See the C<Coro::State::new> constructor for info about the coroutine 196See the C<Coro::State::new> constructor for info about the coro
191environment in which coroutines are executed. 197environment in which coro are executed.
192 198
193Calling C<exit> in a coroutine will do the same as calling exit outside 199Calling C<exit> in a coro will do the same as calling exit outside
194the coroutine. Likewise, when the coroutine dies, the program will exit, 200the coro. Likewise, when the coro dies, the program will exit,
195just as it would in the main program. 201just as it would in the main program.
196 202
197If you do not want that, you can provide a default C<die> handler, or 203If you do not want that, you can provide a default C<die> handler, or
198simply avoid dieing (by use of C<eval>). 204simply avoid dieing (by use of C<eval>).
199 205
200Example: Create a new coroutine that just prints its arguments. 206Example: Create a new coro that just prints its arguments.
201 207
202 async { 208 async {
203 print "@_\n"; 209 print "@_\n";
204 } 1,2,3,4; 210 } 1,2,3,4;
205 211
211 $coro 217 $coro
212} 218}
213 219
214=item async_pool { ... } [@args...] 220=item async_pool { ... } [@args...]
215 221
216Similar to C<async>, but uses a coroutine pool, so you should not call 222Similar 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 223terminate 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 224coro that might have executed other code already (which can be good
219or bad :). 225or bad :).
220 226
221On the plus side, this function is about twice as fast as creating (and 227On 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 228destroying) a completely new coro, so if you need a lot of generic
223coroutines in quick successsion, use C<async_pool>, not C<async>. 229coros in quick successsion, use C<async_pool>, not C<async>.
224 230
225The code block is executed in an C<eval> context and a warning will be 231The 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 232issued 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> 233C<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, 234will not work in the expected way, unless you call terminate or cancel,
229which somehow defeats the purpose of pooling (but is fine in the 235which somehow defeats the purpose of pooling (but is fine in the
230exceptional case). 236exceptional case).
231 237
232The priority will be reset to C<0> after each run, tracing will be 238The priority will be reset to C<0> after each run, tracing will be
233disabled, the description will be reset and the default output filehandle 239disabled, the description will be reset and the default output filehandle
234gets restored, so you can change all these. Otherwise the coroutine will 240gets 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 241be 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 242stuff such as C<$/> you I<must needs> revert that change, which is most
237simply done by using local as in: C<< local $/ >>. 243simply done by using local as in: C<< local $/ >>.
238 244
239The idle pool size is limited to C<8> idle coroutines (this can be 245The 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 246adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle
241coros as required. 247coros as required.
242 248
243If you are concerned about pooled coroutines growing a lot because a 249If 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 250single 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 251{ 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 252addition to that, when the stacks used by a handler grows larger than 32kb
247(adjustable via $Coro::POOL_RSS) it will also be destroyed. 253(adjustable via $Coro::POOL_RSS) it will also be destroyed.
248 254
265=back 271=back
266 272
267=head1 STATIC METHODS 273=head1 STATIC METHODS
268 274
269Static methods are actually functions that implicitly operate on the 275Static methods are actually functions that implicitly operate on the
270current coroutine. 276current coro.
271 277
272=over 4 278=over 4
273 279
274=item schedule 280=item schedule
275 281
276Calls the scheduler. The scheduler will find the next coroutine that is 282Calls the scheduler. The scheduler will find the next coro that is
277to be run from the ready queue and switches to it. The next coroutine 283to be run from the ready queue and switches to it. The next coro
278to be run is simply the one with the highest priority that is longest 284to be run is simply the one with the highest priority that is longest
279in its ready queue. If there is no coroutine ready, it will clal the 285in its ready queue. If there is no coro ready, it will clal the
280C<$Coro::idle> hook. 286C<$Coro::idle> hook.
281 287
282Please note that the current coroutine will I<not> be put into the ready 288Please 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 289queue, so calling this function usually means you will never be called
284again unless something else (e.g. an event handler) calls C<< ->ready >>, 290again unless something else (e.g. an event handler) calls C<< ->ready >>,
285thus waking you up. 291thus waking you up.
286 292
287This makes C<schedule> I<the> generic method to use to block the current 293This 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 294coro and wait for events: first you remember the current coro in
289a variable, then arrange for some callback of yours to call C<< ->ready 295a 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 296>> 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, 297yourself 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 298so you need to check whether the event indeed happened, e.g. by storing the
293status in a variable. 299status in a variable.
294 300
295See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks. 301See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks.
296 302
297=item cede 303=item cede
298 304
299"Cede" to other coroutines. This function puts the current coroutine into 305"Cede" to other coros. This function puts the current coro into
300the ready queue and calls C<schedule>, which has the effect of giving 306the ready queue and calls C<schedule>, which has the effect of giving
301up the current "timeslice" to other coroutines of the same or higher 307up the current "timeslice" to other coros of the same or higher
302priority. Once your coroutine gets its turn again it will automatically be 308priority. Once your coro gets its turn again it will automatically be
303resumed. 309resumed.
304 310
305This function is often called C<yield> in other languages. 311This function is often called C<yield> in other languages.
306 312
307=item Coro::cede_notself 313=item Coro::cede_notself
308 314
309Works like cede, but is not exported by default and will cede to I<any> 315Works like cede, but is not exported by default and will cede to I<any>
310coroutine, regardless of priority. This is useful sometimes to ensure 316coro, regardless of priority. This is useful sometimes to ensure
311progress is made. 317progress is made.
312 318
313=item terminate [arg...] 319=item terminate [arg...]
314 320
315Terminates the current coroutine with the given status values (see L<cancel>). 321Terminates the current coro with the given status values (see L<cancel>).
322
323=item Coro::on_enter BLOCK, Coro::on_leave BLOCK
324
325These function install enter and leave winders in the current scope. The
326enter block will be executed when on_enter is called and whenever the
327current coro is re-entered by the scheduler, while the leave block is
328executed whenever the current coro is blocked by the scheduler, and
329also when the containing scope is exited (by whatever means, be it exit,
330die, last etc.).
331
332I<Neither invoking the scheduler, nor exceptions, are allowed within those
333BLOCKs>. That means: do not even think about calling C<die> without an
334eval, and do not even think of entering the scheduler in any way.
335
336Since both BLOCKs are tied to the current scope, they will automatically
337be removed when the current scope exits.
338
339These functions implement the same concept as C<dynamic-wind> in scheme
340does, and are useful when you want to localise some resource to a specific
341coro.
342
343They slow down coro switching considerably for coros that use
344them (But coro switching is still reasonably fast if the handlers are
345fast).
346
347These functions are best understood by an example: The following function
348will change the current timezone to "Antarctica/South_Pole", which
349requires a call to C<tzset>, but by using C<on_enter> and C<on_leave>,
350which remember/change the current timezone and restore the previous
351value, respectively, the timezone is only changes for the coro that
352installed those handlers.
353
354 use POSIX qw(tzset);
355
356 async {
357 my $old_tz; # store outside TZ value here
358
359 Coro::on_enter {
360 $old_tz = $ENV{TZ}; # remember the old value
361
362 $ENV{TZ} = "Antarctica/South_Pole";
363 tzset; # enable new value
364 };
365
366 Coro::on_leave {
367 $ENV{TZ} = $old_tz;
368 tzset; # restore old value
369 };
370
371 # at this place, the timezone is Antarctica/South_Pole,
372 # without disturbing the TZ of any other coro.
373 };
374
375This can be used to localise about any resource (locale, uid, current
376working directory etc.) to a block, despite the existance of other
377coros.
316 378
317=item killall 379=item killall
318 380
319Kills/terminates/cancels all coroutines except the currently running 381Kills/terminates/cancels all coros except the currently running one.
320one. This is useful after a fork, either in the child or the parent, as
321usually only one of them should inherit the running coroutines.
322 382
323Note that while this will try to free some of the main programs resources, 383Note that while this will try to free some of the main interpreter
384resources if the calling coro isn't the main coro, but one
324you cannot free all of them, so if a coroutine that is not the main 385cannot free all of them, so if a coro that is not the main coro
325program calls this function, there will be some one-time resource leak. 386calls this function, there will be some one-time resource leak.
326 387
327=cut 388=cut
328 389
329sub killall { 390sub killall {
330 for (Coro::State::list) { 391 for (Coro::State::list) {
333 } 394 }
334} 395}
335 396
336=back 397=back
337 398
338=head1 COROUTINE OBJECT METHODS 399=head1 CORO OBJECT METHODS
339 400
340These are the methods you can call on coroutine objects (or to create 401These are the methods you can call on coro objects (or to create
341them). 402them).
342 403
343=over 4 404=over 4
344 405
345=item new Coro \&sub [, @args...] 406=item new Coro \&sub [, @args...]
346 407
347Create a new coroutine and return it. When the sub returns, the coroutine 408Create a new coro and return it. When the sub returns, the coro
348automatically terminates as if C<terminate> with the returned values were 409automatically terminates as if C<terminate> with the returned values were
349called. To make the coroutine run you must first put it into the ready 410called. To make the coro run you must first put it into the ready
350queue by calling the ready method. 411queue by calling the ready method.
351 412
352See C<async> and C<Coro::State::new> for additional info about the 413See C<async> and C<Coro::State::new> for additional info about the
353coroutine environment. 414coro environment.
354 415
355=cut 416=cut
356 417
357sub _coro_run { 418sub _coro_run {
358 terminate &{+shift}; 419 terminate &{+shift};
359} 420}
360 421
361=item $success = $coroutine->ready 422=item $success = $coro->ready
362 423
363Put the given coroutine into the end of its ready queue (there is one 424Put the given coro into the end of its ready queue (there is one
364queue for each priority) and return true. If the coroutine is already in 425queue for each priority) and return true. If the coro is already in
365the ready queue, do nothing and return false. 426the ready queue, do nothing and return false.
366 427
367This ensures that the scheduler will resume this coroutine automatically 428This ensures that the scheduler will resume this coro automatically
368once all the coroutines of higher priority and all coroutines of the same 429once all the coro of higher priority and all coro of the same
369priority that were put into the ready queue earlier have been resumed. 430priority that were put into the ready queue earlier have been resumed.
370 431
432=item $coro->suspend
433
434Suspends the specified coro. A suspended coro works just like any other
435coro, except that the scheduler will not select a suspended coro for
436execution.
437
438Suspending a coro can be useful when you want to keep the coro from
439running, but you don't want to destroy it, or when you want to temporarily
440freeze a coro (e.g. for debugging) to resume it later.
441
442A scenario for the former would be to suspend all (other) coros after a
443fork and keep them alive, so their destructors aren't called, but new
444coros can be created.
445
446=item $coro->resume
447
448If the specified coro was suspended, it will be resumed. Note that when
449the coro was in the ready queue when it was suspended, it might have been
450unreadied by the scheduler, so an activation might have been lost.
451
452To avoid this, it is best to put a suspended coro into the ready queue
453unconditionally, as every synchronisation mechanism must protect itself
454against spurious wakeups, and the one in the Coro family certainly do
455that.
456
371=item $is_ready = $coroutine->is_ready 457=item $is_ready = $coro->is_ready
372 458
373Return whether the coroutine is currently the ready queue or not, 459Returns true iff the Coro object is in the ready queue. Unless the Coro
460object gets destroyed, it will eventually be scheduled by the scheduler.
374 461
462=item $is_running = $coro->is_running
463
464Returns true iff the Coro object is currently running. Only one Coro object
465can ever be in the running state (but it currently is possible to have
466multiple running Coro::States).
467
468=item $is_suspended = $coro->is_suspended
469
470Returns true iff this Coro object has been suspended. Suspended Coros will
471not ever be scheduled.
472
375=item $coroutine->cancel (arg...) 473=item $coro->cancel (arg...)
376 474
377Terminates the given coroutine and makes it return the given arguments as 475Terminates the given Coro and makes it return the given arguments as
378status (default: the empty list). Never returns if the coroutine is the 476status (default: the empty list). Never returns if the Coro is the
379current coroutine. 477current Coro.
380 478
381=cut 479=cut
382 480
383sub cancel { 481sub cancel {
384 my $self = shift; 482 my $self = shift;
385 483
386 if ($current == $self) { 484 if ($current == $self) {
387 terminate @_; 485 terminate @_;
388 } else { 486 } else {
389 $self->{_status} = [@_]; 487 $self->{_status} = [@_];
390 $self->_cancel; 488 Coro::State::cancel $self;
391 } 489 }
392} 490}
393 491
394=item $coroutine->schedule_to 492=item $coro->schedule_to
395 493
396Puts the current coroutine to sleep (like C<Coro::schedule>), but instead 494Puts the current coro to sleep (like C<Coro::schedule>), but instead
397of continuing with the next coro from the ready queue, always switch to 495of continuing with the next coro from the ready queue, always switch to
398the given coroutine object (regardless of priority etc.). The readyness 496the given coro object (regardless of priority etc.). The readyness
399state of that coroutine isn't changed. 497state of that coro isn't changed.
400 498
401This is an advanced method for special cases - I'd love to hear about any 499This is an advanced method for special cases - I'd love to hear about any
402uses for this one. 500uses for this one.
403 501
404=item $coroutine->cede_to 502=item $coro->cede_to
405 503
406Like C<schedule_to>, but puts the current coroutine into the ready 504Like C<schedule_to>, but puts the current coro into the ready
407queue. This has the effect of temporarily switching to the given 505queue. This has the effect of temporarily switching to the given
408coroutine, and continuing some time later. 506coro, and continuing some time later.
409 507
410This is an advanced method for special cases - I'd love to hear about any 508This is an advanced method for special cases - I'd love to hear about any
411uses for this one. 509uses for this one.
412 510
413=item $coroutine->throw ([$scalar]) 511=item $coro->throw ([$scalar])
414 512
415If C<$throw> is specified and defined, it will be thrown as an exception 513If C<$throw> is specified and defined, it will be thrown as an exception
416inside the coroutine at the next convenient point in time. Otherwise 514inside the coro at the next convenient point in time. Otherwise
417clears the exception object. 515clears the exception object.
418 516
419Coro will check for the exception each time a schedule-like-function 517Coro will check for the exception each time a schedule-like-function
420returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down 518returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down
421>>, C<< Coro::Handle->readable >> and so on. Most of these functions 519>>, C<< Coro::Handle->readable >> and so on. Most of these functions
423 521
424The exception object will be thrown "as is" with the specified scalar in 522The exception object will be thrown "as is" with the specified scalar in
425C<$@>, i.e. if it is a string, no line number or newline will be appended 523C<$@>, i.e. if it is a string, no line number or newline will be appended
426(unlike with C<die>). 524(unlike with C<die>).
427 525
428This can be used as a softer means than C<cancel> to ask a coroutine to 526This can be used as a softer means than C<cancel> to ask a coro to
429end itself, although there is no guarantee that the exception will lead to 527end itself, although there is no guarantee that the exception will lead to
430termination, and if the exception isn't caught it might well end the whole 528termination, and if the exception isn't caught it might well end the whole
431program. 529program.
432 530
433You might also think of C<throw> as being the moral equivalent of 531You might also think of C<throw> as being the moral equivalent of
434C<kill>ing a coroutine with a signal (in this case, a scalar). 532C<kill>ing a coro with a signal (in this case, a scalar).
435 533
436=item $coroutine->join 534=item $coro->join
437 535
438Wait until the coroutine terminates and return any values given to the 536Wait until the coro terminates and return any values given to the
439C<terminate> or C<cancel> functions. C<join> can be called concurrently 537C<terminate> or C<cancel> functions. C<join> can be called concurrently
440from multiple coroutines, and all will be resumed and given the status 538from multiple coro, and all will be resumed and given the status
441return once the C<$coroutine> terminates. 539return once the C<$coro> terminates.
442 540
443=cut 541=cut
444 542
445sub join { 543sub join {
446 my $self = shift; 544 my $self = shift;
457 } 555 }
458 556
459 wantarray ? @{$self->{_status}} : $self->{_status}[0]; 557 wantarray ? @{$self->{_status}} : $self->{_status}[0];
460} 558}
461 559
462=item $coroutine->on_destroy (\&cb) 560=item $coro->on_destroy (\&cb)
463 561
464Registers a callback that is called when this coroutine gets destroyed, 562Registers a callback that is called when this coro gets destroyed,
465but before it is joined. The callback gets passed the terminate arguments, 563but before it is joined. The callback gets passed the terminate arguments,
466if any, and I<must not> die, under any circumstances. 564if any, and I<must not> die, under any circumstances.
467 565
468=cut 566=cut
469 567
471 my ($self, $cb) = @_; 569 my ($self, $cb) = @_;
472 570
473 push @{ $self->{_on_destroy} }, $cb; 571 push @{ $self->{_on_destroy} }, $cb;
474} 572}
475 573
476=item $oldprio = $coroutine->prio ($newprio) 574=item $oldprio = $coro->prio ($newprio)
477 575
478Sets (or gets, if the argument is missing) the priority of the 576Sets (or gets, if the argument is missing) the priority of the
479coroutine. Higher priority coroutines get run before lower priority 577coro. Higher priority coro get run before lower priority
480coroutines. Priorities are small signed integers (currently -4 .. +3), 578coro. Priorities are small signed integers (currently -4 .. +3),
481that you can refer to using PRIO_xxx constants (use the import tag :prio 579that you can refer to using PRIO_xxx constants (use the import tag :prio
482to get then): 580to get then):
483 581
484 PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN 582 PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
485 3 > 1 > 0 > -1 > -3 > -4 583 3 > 1 > 0 > -1 > -3 > -4
486 584
487 # set priority to HIGH 585 # set priority to HIGH
488 current->prio(PRIO_HIGH); 586 current->prio (PRIO_HIGH);
489 587
490The idle coroutine ($Coro::idle) always has a lower priority than any 588The idle coro ($Coro::idle) always has a lower priority than any
491existing coroutine. 589existing coro.
492 590
493Changing the priority of the current coroutine will take effect immediately, 591Changing the priority of the current coro will take effect immediately,
494but changing the priority of coroutines in the ready queue (but not 592but changing the priority of coro in the ready queue (but not
495running) will only take effect after the next schedule (of that 593running) will only take effect after the next schedule (of that
496coroutine). This is a bug that will be fixed in some future version. 594coro). This is a bug that will be fixed in some future version.
497 595
498=item $newprio = $coroutine->nice ($change) 596=item $newprio = $coro->nice ($change)
499 597
500Similar to C<prio>, but subtract the given value from the priority (i.e. 598Similar to C<prio>, but subtract the given value from the priority (i.e.
501higher values mean lower priority, just as in unix). 599higher values mean lower priority, just as in unix).
502 600
503=item $olddesc = $coroutine->desc ($newdesc) 601=item $olddesc = $coro->desc ($newdesc)
504 602
505Sets (or gets in case the argument is missing) the description for this 603Sets (or gets in case the argument is missing) the description for this
506coroutine. This is just a free-form string you can associate with a 604coro. This is just a free-form string you can associate with a
507coroutine. 605coro.
508 606
509This method simply sets the C<< $coroutine->{desc} >> member to the given 607This method simply sets the C<< $coro->{desc} >> member to the given
510string. You can modify this member directly if you wish. 608string. You can modify this member directly if you wish.
511 609
512=cut 610=cut
513 611
514sub desc { 612sub desc {
528 626
529=over 4 627=over 4
530 628
531=item Coro::nready 629=item Coro::nready
532 630
533Returns the number of coroutines that are currently in the ready state, 631Returns the number of coro that are currently in the ready state,
534i.e. that can be switched to by calling C<schedule> directory or 632i.e. that can be switched to by calling C<schedule> directory or
535indirectly. The value C<0> means that the only runnable coroutine is the 633indirectly. The value C<0> means that the only runnable coro is the
536currently running one, so C<cede> would have no effect, and C<schedule> 634currently running one, so C<cede> would have no effect, and C<schedule>
537would cause a deadlock unless there is an idle handler that wakes up some 635would cause a deadlock unless there is an idle handler that wakes up some
538coroutines. 636coro.
539 637
540=item my $guard = Coro::guard { ... } 638=item my $guard = Coro::guard { ... }
541 639
542This creates and returns a guard object. Nothing happens until the object 640This function still exists, but is deprecated. Please use the
543gets destroyed, in which case the codeblock given as argument will be 641C<Guard::guard> function instead.
544executed. This is useful to free locks or other resources in case of a
545runtime error or when the coroutine gets canceled, as in both cases the
546guard block will be executed. The guard object supports only one method,
547C<< ->cancel >>, which will keep the codeblock from being executed.
548 642
549Example: set some flag and clear it again when the coroutine gets canceled
550or the function returns:
551
552 sub do_something {
553 my $guard = Coro::guard { $busy = 0 };
554 $busy = 1;
555
556 # do something that requires $busy to be true
557 }
558
559=cut 643=cut
560 644
561sub guard(&) { 645BEGIN { *guard = \&Guard::guard }
562 bless \(my $cb = $_[0]), "Coro::guard"
563}
564
565sub Coro::guard::cancel {
566 ${$_[0]} = sub { };
567}
568
569sub Coro::guard::DESTROY {
570 ${$_[0]}->();
571}
572
573 646
574=item unblock_sub { ... } 647=item unblock_sub { ... }
575 648
576This utility function takes a BLOCK or code reference and "unblocks" it, 649This utility function takes a BLOCK or code reference and "unblocks" it,
577returning a new coderef. Unblocking means that calling the new coderef 650returning a new coderef. Unblocking means that calling the new coderef
578will return immediately without blocking, returning nothing, while the 651will return immediately without blocking, returning nothing, while the
579original code ref will be called (with parameters) from within another 652original code ref will be called (with parameters) from within another
580coroutine. 653coro.
581 654
582The reason this function exists is that many event libraries (such as the 655The reason this function exists is that many event libraries (such as the
583venerable L<Event|Event> module) are not coroutine-safe (a weaker form 656venerable L<Event|Event> module) are not thread-safe (a weaker form
584of reentrancy). This means you must not block within event callbacks, 657of reentrancy). This means you must not block within event callbacks,
585otherwise you might suffer from crashes or worse. The only event library 658otherwise you might suffer from crashes or worse. The only event library
586currently known that is safe to use without C<unblock_sub> is L<EV>. 659currently known that is safe to use without C<unblock_sub> is L<EV>.
587 660
588This function allows your callbacks to block by executing them in another 661This function allows your callbacks to block by executing them in another
589coroutine where it is safe to block. One example where blocking is handy 662coro where it is safe to block. One example where blocking is handy
590is when you use the L<Coro::AIO|Coro::AIO> functions to save results to 663is when you use the L<Coro::AIO|Coro::AIO> functions to save results to
591disk, for example. 664disk, for example.
592 665
593In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when 666In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
594creating event callbacks that want to block. 667creating event callbacks that want to block.
595 668
596If your handler does not plan to block (e.g. simply sends a message to 669If your handler does not plan to block (e.g. simply sends a message to
597another coroutine, or puts some other coroutine into the ready queue), 670another coro, or puts some other coro into the ready queue), there is
598there is no reason to use C<unblock_sub>. 671no reason to use C<unblock_sub>.
599 672
600Note that you also need to use C<unblock_sub> for any other callbacks that 673Note that you also need to use C<unblock_sub> for any other callbacks that
601are indirectly executed by any C-based event loop. For example, when you 674are indirectly executed by any C-based event loop. For example, when you
602use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it 675use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it
603provides callbacks that are the result of some event callback, then you 676provides callbacks that are the result of some event callback, then you
637 710
638=item $cb = Coro::rouse_cb 711=item $cb = Coro::rouse_cb
639 712
640Create and return a "rouse callback". That's a code reference that, 713Create and return a "rouse callback". That's a code reference that,
641when called, will remember a copy of its arguments and notify the owner 714when called, will remember a copy of its arguments and notify the owner
642coroutine of the callback. 715coro of the callback.
643 716
644See the next function. 717See the next function.
645 718
646=item @args = Coro::rouse_wait [$cb] 719=item @args = Coro::rouse_wait [$cb]
647 720
648Wait for the specified rouse callback (or the last one that was created in 721Wait for the specified rouse callback (or the last one that was created in
649this coroutine). 722this coro).
650 723
651As soon as the callback is invoked (or when the callback was invoked 724As soon as the callback is invoked (or when the callback was invoked
652before C<rouse_wait>), it will return the arguments originally passed to 725before C<rouse_wait>), it will return the arguments originally passed to
653the rouse callback. 726the rouse callback.
654 727
660 733
6611; 7341;
662 735
663=head1 HOW TO WAIT FOR A CALLBACK 736=head1 HOW TO WAIT FOR A CALLBACK
664 737
665It is very common for a coroutine to wait for some callback to be 738It is very common for a coro to wait for some callback to be
666called. This occurs naturally when you use coroutines in an otherwise 739called. This occurs naturally when you use coro in an otherwise
667event-based program, or when you use event-based libraries. 740event-based program, or when you use event-based libraries.
668 741
669These typically register a callback for some event, and call that callback 742These typically register a callback for some event, and call that callback
670when the event occured. In a coroutine, however, you typically want to 743when the event occured. In a coro, however, you typically want to
671just wait for the event, simplyifying things. 744just wait for the event, simplyifying things.
672 745
673For example C<< AnyEvent->child >> registers a callback to be called when 746For example C<< AnyEvent->child >> registers a callback to be called when
674a specific child has exited: 747a specific child has exited:
675 748
676 my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... }); 749 my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... });
677 750
678But from withina coroutine, you often just want to write this: 751But from within a coro, you often just want to write this:
679 752
680 my $status = wait_for_child $pid; 753 my $status = wait_for_child $pid;
681 754
682Coro offers two functions specifically designed to make this easy, 755Coro offers two functions specifically designed to make this easy,
683C<Coro::rouse_cb> and C<Coro::rouse_wait>. 756C<Coro::rouse_cb> and C<Coro::rouse_wait>.
684 757
685The first function, C<rouse_cb>, generates and returns a callback that, 758The first function, C<rouse_cb>, generates and returns a callback that,
686when invoked, will save its arguments and notify the coroutine that 759when invoked, will save its arguments and notify the coro that
687created the callback. 760created the callback.
688 761
689The second function, C<rouse_wait>, waits for the callback to be called 762The second function, C<rouse_wait>, waits for the callback to be called
690(by calling C<schedule> to go to sleep) and returns the arguments 763(by calling C<schedule> to go to sleep) and returns the arguments
691originally passed to the callback. 764originally passed to the callback.
706you can roll your own, using C<schedule>: 779you can roll your own, using C<schedule>:
707 780
708 sub wait_for_child($) { 781 sub wait_for_child($) {
709 my ($pid) = @_; 782 my ($pid) = @_;
710 783
711 # store the current coroutine in $current, 784 # store the current coro in $current,
712 # and provide result variables for the closure passed to ->child 785 # and provide result variables for the closure passed to ->child
713 my $current = $Coro::current; 786 my $current = $Coro::current;
714 my ($done, $rstatus); 787 my ($done, $rstatus);
715 788
716 # pass a closure to ->child 789 # pass a closure to ->child
732 805
733=item fork with pthread backend 806=item fork with pthread backend
734 807
735When Coro is compiled using the pthread backend (which isn't recommended 808When Coro is compiled using the pthread backend (which isn't recommended
736but required on many BSDs as their libcs are completely broken), then 809but required on many BSDs as their libcs are completely broken), then
737coroutines will not survive a fork. There is no known workaround except to 810coro will not survive a fork. There is no known workaround except to
738fix your libc and use a saner backend. 811fix your libc and use a saner backend.
739 812
740=item perl process emulation ("threads") 813=item perl process emulation ("threads")
741 814
742This module is not perl-pseudo-thread-safe. You should only ever use this 815This module is not perl-pseudo-thread-safe. You should only ever use this
744future to allow per-thread schedulers, but Coro::State does not yet allow 817future to allow per-thread schedulers, but Coro::State does not yet allow
745this). I recommend disabling thread support and using processes, as having 818this). I recommend disabling thread support and using processes, as having
746the windows process emulation enabled under unix roughly halves perl 819the windows process emulation enabled under unix roughly halves perl
747performance, even when not used. 820performance, even when not used.
748 821
749=item coroutine switching not signal safe 822=item coro switching is not signal safe
750 823
751You must not switch to another coroutine from within a signal handler 824You must not switch to another coro from within a signal handler
752(only relevant with %SIG - most event libraries provide safe signals). 825(only relevant with %SIG - most event libraries provide safe signals).
753 826
754That means you I<MUST NOT> call any function that might "block" the 827That means you I<MUST NOT> call any function that might "block" the
755current coroutine - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or 828current coro - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or
756anything that calls those. Everything else, including calling C<ready>, 829anything that calls those. Everything else, including calling C<ready>,
757works. 830works.
758 831
759=back 832=back
760 833

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