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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 = 5.13; 85our $VERSION = 5.14;
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 thread switching considerably for coros that use them
344(about 40% for a BLOCK with a single assignment, so thread switching is
345still reasonably fast if the handlers are fast).
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 changed 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.
378
379Another interesting example implements time-sliced multitasking using
380interval timers (this could obviously be optimised, but does the job):
381
382 # "timeslice" the given block
383 sub timeslice(&) {
384 use Time::HiRes ();
385
386 Coro::on_enter {
387 # on entering the thread, we set an VTALRM handler to cede
388 $SIG{VTALRM} = sub { cede };
389 # and then start the interval timer
390 Time::HiRes::setitimer &Time::HiRes::ITIMER_VIRTUAL, 0.01, 0.01;
391 };
392 Coro::on_leave {
393 # on leaving the thread, we stop the interval timer again
394 Time::HiRes::setitimer &Time::HiRes::ITIMER_VIRTUAL, 0, 0;
395 };
396
397 &{+shift};
398 }
399
400 # use like this:
401 timeslice {
402 # The following is an endless loop that would normally
403 # monopolise the process. Since it runs in a timesliced
404 # environment, it will regularly cede to other threads.
405 while () { }
406 };
407
316 408
317=item killall 409=item killall
318 410
319Kills/terminates/cancels all coroutines except the currently running 411Kills/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.
322 412
323Note that while this will try to free some of the main programs resources, 413Note that while this will try to free some of the main interpreter
414resources 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 415cannot 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. 416calls this function, there will be some one-time resource leak.
326 417
327=cut 418=cut
328 419
329sub killall { 420sub killall {
330 for (Coro::State::list) { 421 for (Coro::State::list) {
… …
333 } 424 }
334} 425}
335 426
336=back 427=back
337 428
338=head1 COROUTINE OBJECT METHODS 429=head1 CORO OBJECT METHODS
339 430
340These are the methods you can call on coroutine objects (or to create 431These are the methods you can call on coro objects (or to create
341them). 432them).
342 433
343=over 4 434=over 4
344 435
345=item new Coro \&sub [, @args...] 436=item new Coro \&sub [, @args...]
346 437
347Create a new coroutine and return it. When the sub returns, the coroutine 438Create a new coro and return it. When the sub returns, the coro
348automatically terminates as if C<terminate> with the returned values were 439automatically terminates as if C<terminate> with the returned values were
349called. To make the coroutine run you must first put it into the ready 440called. To make the coro run you must first put it into the ready
350queue by calling the ready method. 441queue by calling the ready method.
351 442
352See C<async> and C<Coro::State::new> for additional info about the 443See C<async> and C<Coro::State::new> for additional info about the
353coroutine environment. 444coro environment.
354 445
355=cut 446=cut
356 447
357sub _coro_run { 448sub _coro_run {
358 terminate &{+shift}; 449 terminate &{+shift};
359} 450}
360 451
361=item $success = $coroutine->ready 452=item $success = $coro->ready
362 453
363Put the given coroutine into the end of its ready queue (there is one 454Put 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 455queue for each priority) and return true. If the coro is already in
365the ready queue, do nothing and return false. 456the ready queue, do nothing and return false.
366 457
367This ensures that the scheduler will resume this coroutine automatically 458This ensures that the scheduler will resume this coro automatically
368once all the coroutines of higher priority and all coroutines of the same 459once all the coro of higher priority and all coro of the same
369priority that were put into the ready queue earlier have been resumed. 460priority that were put into the ready queue earlier have been resumed.
370 461
462=item $coro->suspend
463
464Suspends the specified coro. A suspended coro works just like any other
465coro, except that the scheduler will not select a suspended coro for
466execution.
467
468Suspending a coro can be useful when you want to keep the coro from
469running, but you don't want to destroy it, or when you want to temporarily
470freeze a coro (e.g. for debugging) to resume it later.
471
472A scenario for the former would be to suspend all (other) coros after a
473fork and keep them alive, so their destructors aren't called, but new
474coros can be created.
475
476=item $coro->resume
477
478If the specified coro was suspended, it will be resumed. Note that when
479the coro was in the ready queue when it was suspended, it might have been
480unreadied by the scheduler, so an activation might have been lost.
481
482To avoid this, it is best to put a suspended coro into the ready queue
483unconditionally, as every synchronisation mechanism must protect itself
484against spurious wakeups, and the one in the Coro family certainly do
485that.
486
371=item $is_ready = $coroutine->is_ready 487=item $is_ready = $coro->is_ready
372 488
373Return whether the coroutine is currently the ready queue or not, 489Returns true iff the Coro object is in the ready queue. Unless the Coro
490object gets destroyed, it will eventually be scheduled by the scheduler.
374 491
492=item $is_running = $coro->is_running
493
494Returns true iff the Coro object is currently running. Only one Coro object
495can ever be in the running state (but it currently is possible to have
496multiple running Coro::States).
497
498=item $is_suspended = $coro->is_suspended
499
500Returns true iff this Coro object has been suspended. Suspended Coros will
501not ever be scheduled.
502
375=item $coroutine->cancel (arg...) 503=item $coro->cancel (arg...)
376 504
377Terminates the given coroutine and makes it return the given arguments as 505Terminates the given Coro and makes it return the given arguments as
378status (default: the empty list). Never returns if the coroutine is the 506status (default: the empty list). Never returns if the Coro is the
379current coroutine. 507current Coro.
380 508
381=cut 509=cut
382 510
383sub cancel { 511sub cancel {
384 my $self = shift; 512 my $self = shift;
385 513
386 if ($current == $self) { 514 if ($current == $self) {
387 terminate @_; 515 terminate @_;
388 } else { 516 } else {
389 $self->{_status} = [@_]; 517 $self->{_status} = [@_];
390 $self->_cancel; 518 Coro::State::cancel $self;
391 } 519 }
392} 520}
393 521
394=item $coroutine->schedule_to 522=item $coro->schedule_to
395 523
396Puts the current coroutine to sleep (like C<Coro::schedule>), but instead 524Puts the current coro to sleep (like C<Coro::schedule>), but instead
397of continuing with the next coro from the ready queue, always switch to 525of continuing with the next coro from the ready queue, always switch to
398the given coroutine object (regardless of priority etc.). The readyness 526the given coro object (regardless of priority etc.). The readyness
399state of that coroutine isn't changed. 527state of that coro isn't changed.
400 528
401This is an advanced method for special cases - I'd love to hear about any 529This is an advanced method for special cases - I'd love to hear about any
402uses for this one. 530uses for this one.
403 531
404=item $coroutine->cede_to 532=item $coro->cede_to
405 533
406Like C<schedule_to>, but puts the current coroutine into the ready 534Like C<schedule_to>, but puts the current coro into the ready
407queue. This has the effect of temporarily switching to the given 535queue. This has the effect of temporarily switching to the given
408coroutine, and continuing some time later. 536coro, and continuing some time later.
409 537
410This is an advanced method for special cases - I'd love to hear about any 538This is an advanced method for special cases - I'd love to hear about any
411uses for this one. 539uses for this one.
412 540
413=item $coroutine->throw ([$scalar]) 541=item $coro->throw ([$scalar])
414 542
415If C<$throw> is specified and defined, it will be thrown as an exception 543If C<$throw> is specified and defined, it will be thrown as an exception
416inside the coroutine at the next convenient point in time. Otherwise 544inside the coro at the next convenient point in time. Otherwise
417clears the exception object. 545clears the exception object.
418 546
419Coro will check for the exception each time a schedule-like-function 547Coro will check for the exception each time a schedule-like-function
420returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down 548returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down
421>>, C<< Coro::Handle->readable >> and so on. Most of these functions 549>>, C<< Coro::Handle->readable >> and so on. Most of these functions
… …
423 551
424The exception object will be thrown "as is" with the specified scalar in 552The exception object will be thrown "as is" with the specified scalar in
425C<$@>, i.e. if it is a string, no line number or newline will be appended 553C<$@>, i.e. if it is a string, no line number or newline will be appended
426(unlike with C<die>). 554(unlike with C<die>).
427 555
428This can be used as a softer means than C<cancel> to ask a coroutine to 556This 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 557end 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 558termination, and if the exception isn't caught it might well end the whole
431program. 559program.
432 560
433You might also think of C<throw> as being the moral equivalent of 561You 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). 562C<kill>ing a coro with a signal (in this case, a scalar).
435 563
436=item $coroutine->join 564=item $coro->join
437 565
438Wait until the coroutine terminates and return any values given to the 566Wait until the coro terminates and return any values given to the
439C<terminate> or C<cancel> functions. C<join> can be called concurrently 567C<terminate> or C<cancel> functions. C<join> can be called concurrently
440from multiple coroutines, and all will be resumed and given the status 568from multiple coro, and all will be resumed and given the status
441return once the C<$coroutine> terminates. 569return once the C<$coro> terminates.
442 570
443=cut 571=cut
444 572
445sub join { 573sub join {
446 my $self = shift; 574 my $self = shift;
… …
457 } 585 }
458 586
459 wantarray ? @{$self->{_status}} : $self->{_status}[0]; 587 wantarray ? @{$self->{_status}} : $self->{_status}[0];
460} 588}
461 589
462=item $coroutine->on_destroy (\&cb) 590=item $coro->on_destroy (\&cb)
463 591
464Registers a callback that is called when this coroutine gets destroyed, 592Registers a callback that is called when this coro gets destroyed,
465but before it is joined. The callback gets passed the terminate arguments, 593but before it is joined. The callback gets passed the terminate arguments,
466if any, and I<must not> die, under any circumstances. 594if any, and I<must not> die, under any circumstances.
467 595
468=cut 596=cut
469 597
… …
471 my ($self, $cb) = @_; 599 my ($self, $cb) = @_;
472 600
473 push @{ $self->{_on_destroy} }, $cb; 601 push @{ $self->{_on_destroy} }, $cb;
474} 602}
475 603
476=item $oldprio = $coroutine->prio ($newprio) 604=item $oldprio = $coro->prio ($newprio)
477 605
478Sets (or gets, if the argument is missing) the priority of the 606Sets (or gets, if the argument is missing) the priority of the
479coroutine. Higher priority coroutines get run before lower priority 607coro. Higher priority coro get run before lower priority
480coroutines. Priorities are small signed integers (currently -4 .. +3), 608coro. Priorities are small signed integers (currently -4 .. +3),
481that you can refer to using PRIO_xxx constants (use the import tag :prio 609that you can refer to using PRIO_xxx constants (use the import tag :prio
482to get then): 610to get then):
483 611
484 PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN 612 PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
485 3 > 1 > 0 > -1 > -3 > -4 613 3 > 1 > 0 > -1 > -3 > -4
486 614
487 # set priority to HIGH 615 # set priority to HIGH
488 current->prio(PRIO_HIGH); 616 current->prio (PRIO_HIGH);
489 617
490The idle coroutine ($Coro::idle) always has a lower priority than any 618The idle coro ($Coro::idle) always has a lower priority than any
491existing coroutine. 619existing coro.
492 620
493Changing the priority of the current coroutine will take effect immediately, 621Changing the priority of the current coro will take effect immediately,
494but changing the priority of coroutines in the ready queue (but not 622but changing the priority of coro in the ready queue (but not
495running) will only take effect after the next schedule (of that 623running) will only take effect after the next schedule (of that
496coroutine). This is a bug that will be fixed in some future version. 624coro). This is a bug that will be fixed in some future version.
497 625
498=item $newprio = $coroutine->nice ($change) 626=item $newprio = $coro->nice ($change)
499 627
500Similar to C<prio>, but subtract the given value from the priority (i.e. 628Similar to C<prio>, but subtract the given value from the priority (i.e.
501higher values mean lower priority, just as in unix). 629higher values mean lower priority, just as in unix).
502 630
503=item $olddesc = $coroutine->desc ($newdesc) 631=item $olddesc = $coro->desc ($newdesc)
504 632
505Sets (or gets in case the argument is missing) the description for this 633Sets (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 634coro. This is just a free-form string you can associate with a
507coroutine. 635coro.
508 636
509This method simply sets the C<< $coroutine->{desc} >> member to the given 637This method simply sets the C<< $coro->{desc} >> member to the given
510string. You can modify this member directly if you wish. 638string. You can modify this member directly if you wish.
511 639
512=cut 640=cut
513 641
514sub desc { 642sub desc {
… …
528 656
529=over 4 657=over 4
530 658
531=item Coro::nready 659=item Coro::nready
532 660
533Returns the number of coroutines that are currently in the ready state, 661Returns the number of coro that are currently in the ready state,
534i.e. that can be switched to by calling C<schedule> directory or 662i.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 663indirectly. 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> 664currently 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 665would cause a deadlock unless there is an idle handler that wakes up some
538coroutines. 666coro.
539 667
540=item my $guard = Coro::guard { ... } 668=item my $guard = Coro::guard { ... }
541 669
542This function still exists, but is deprecated. Please use the 670This function still exists, but is deprecated. Please use the
543C<Guard::guard> function instead. 671C<Guard::guard> function instead.
… …
550 678
551This utility function takes a BLOCK or code reference and "unblocks" it, 679This utility function takes a BLOCK or code reference and "unblocks" it,
552returning a new coderef. Unblocking means that calling the new coderef 680returning a new coderef. Unblocking means that calling the new coderef
553will return immediately without blocking, returning nothing, while the 681will return immediately without blocking, returning nothing, while the
554original code ref will be called (with parameters) from within another 682original code ref will be called (with parameters) from within another
555coroutine. 683coro.
556 684
557The reason this function exists is that many event libraries (such as the 685The reason this function exists is that many event libraries (such as the
558venerable L<Event|Event> module) are not coroutine-safe (a weaker form 686venerable L<Event|Event> module) are not thread-safe (a weaker form
559of reentrancy). This means you must not block within event callbacks, 687of reentrancy). This means you must not block within event callbacks,
560otherwise you might suffer from crashes or worse. The only event library 688otherwise you might suffer from crashes or worse. The only event library
561currently known that is safe to use without C<unblock_sub> is L<EV>. 689currently known that is safe to use without C<unblock_sub> is L<EV>.
562 690
563This function allows your callbacks to block by executing them in another 691This function allows your callbacks to block by executing them in another
564coroutine where it is safe to block. One example where blocking is handy 692coro where it is safe to block. One example where blocking is handy
565is when you use the L<Coro::AIO|Coro::AIO> functions to save results to 693is when you use the L<Coro::AIO|Coro::AIO> functions to save results to
566disk, for example. 694disk, for example.
567 695
568In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when 696In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
569creating event callbacks that want to block. 697creating event callbacks that want to block.
570 698
571If your handler does not plan to block (e.g. simply sends a message to 699If your handler does not plan to block (e.g. simply sends a message to
572another coroutine, or puts some other coroutine into the ready queue), 700another coro, or puts some other coro into the ready queue), there is
573there is no reason to use C<unblock_sub>. 701no reason to use C<unblock_sub>.
574 702
575Note that you also need to use C<unblock_sub> for any other callbacks that 703Note that you also need to use C<unblock_sub> for any other callbacks that
576are indirectly executed by any C-based event loop. For example, when you 704are indirectly executed by any C-based event loop. For example, when you
577use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it 705use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it
578provides callbacks that are the result of some event callback, then you 706provides callbacks that are the result of some event callback, then you
… …
612 740
613=item $cb = Coro::rouse_cb 741=item $cb = Coro::rouse_cb
614 742
615Create and return a "rouse callback". That's a code reference that, 743Create and return a "rouse callback". That's a code reference that,
616when called, will remember a copy of its arguments and notify the owner 744when called, will remember a copy of its arguments and notify the owner
617coroutine of the callback. 745coro of the callback.
618 746
619See the next function. 747See the next function.
620 748
621=item @args = Coro::rouse_wait [$cb] 749=item @args = Coro::rouse_wait [$cb]
622 750
623Wait for the specified rouse callback (or the last one that was created in 751Wait for the specified rouse callback (or the last one that was created in
624this coroutine). 752this coro).
625 753
626As soon as the callback is invoked (or when the callback was invoked 754As soon as the callback is invoked (or when the callback was invoked
627before C<rouse_wait>), it will return the arguments originally passed to 755before C<rouse_wait>), it will return the arguments originally passed to
628the rouse callback. 756the rouse callback.
629 757
… …
635 763
6361; 7641;
637 765
638=head1 HOW TO WAIT FOR A CALLBACK 766=head1 HOW TO WAIT FOR A CALLBACK
639 767
640It is very common for a coroutine to wait for some callback to be 768It is very common for a coro to wait for some callback to be
641called. This occurs naturally when you use coroutines in an otherwise 769called. This occurs naturally when you use coro in an otherwise
642event-based program, or when you use event-based libraries. 770event-based program, or when you use event-based libraries.
643 771
644These typically register a callback for some event, and call that callback 772These typically register a callback for some event, and call that callback
645when the event occured. In a coroutine, however, you typically want to 773when the event occured. In a coro, however, you typically want to
646just wait for the event, simplyifying things. 774just wait for the event, simplyifying things.
647 775
648For example C<< AnyEvent->child >> registers a callback to be called when 776For example C<< AnyEvent->child >> registers a callback to be called when
649a specific child has exited: 777a specific child has exited:
650 778
651 my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... }); 779 my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... });
652 780
653But from withina coroutine, you often just want to write this: 781But from within a coro, you often just want to write this:
654 782
655 my $status = wait_for_child $pid; 783 my $status = wait_for_child $pid;
656 784
657Coro offers two functions specifically designed to make this easy, 785Coro offers two functions specifically designed to make this easy,
658C<Coro::rouse_cb> and C<Coro::rouse_wait>. 786C<Coro::rouse_cb> and C<Coro::rouse_wait>.
659 787
660The first function, C<rouse_cb>, generates and returns a callback that, 788The first function, C<rouse_cb>, generates and returns a callback that,
661when invoked, will save its arguments and notify the coroutine that 789when invoked, will save its arguments and notify the coro that
662created the callback. 790created the callback.
663 791
664The second function, C<rouse_wait>, waits for the callback to be called 792The second function, C<rouse_wait>, waits for the callback to be called
665(by calling C<schedule> to go to sleep) and returns the arguments 793(by calling C<schedule> to go to sleep) and returns the arguments
666originally passed to the callback. 794originally passed to the callback.
… …
681you can roll your own, using C<schedule>: 809you can roll your own, using C<schedule>:
682 810
683 sub wait_for_child($) { 811 sub wait_for_child($) {
684 my ($pid) = @_; 812 my ($pid) = @_;
685 813
686 # store the current coroutine in $current, 814 # store the current coro in $current,
687 # and provide result variables for the closure passed to ->child 815 # and provide result variables for the closure passed to ->child
688 my $current = $Coro::current; 816 my $current = $Coro::current;
689 my ($done, $rstatus); 817 my ($done, $rstatus);
690 818
691 # pass a closure to ->child 819 # pass a closure to ->child
… …
707 835
708=item fork with pthread backend 836=item fork with pthread backend
709 837
710When Coro is compiled using the pthread backend (which isn't recommended 838When Coro is compiled using the pthread backend (which isn't recommended
711but required on many BSDs as their libcs are completely broken), then 839but required on many BSDs as their libcs are completely broken), then
712coroutines will not survive a fork. There is no known workaround except to 840coro will not survive a fork. There is no known workaround except to
713fix your libc and use a saner backend. 841fix your libc and use a saner backend.
714 842
715=item perl process emulation ("threads") 843=item perl process emulation ("threads")
716 844
717This module is not perl-pseudo-thread-safe. You should only ever use this 845This module is not perl-pseudo-thread-safe. You should only ever use this
… …
719future to allow per-thread schedulers, but Coro::State does not yet allow 847future to allow per-thread schedulers, but Coro::State does not yet allow
720this). I recommend disabling thread support and using processes, as having 848this). I recommend disabling thread support and using processes, as having
721the windows process emulation enabled under unix roughly halves perl 849the windows process emulation enabled under unix roughly halves perl
722performance, even when not used. 850performance, even when not used.
723 851
724=item coroutine switching not signal safe 852=item coro switching is not signal safe
725 853
726You must not switch to another coroutine from within a signal handler 854You must not switch to another coro from within a signal handler
727(only relevant with %SIG - most event libraries provide safe signals). 855(only relevant with %SIG - most event libraries provide safe signals).
728 856
729That means you I<MUST NOT> call any function that might "block" the 857That means you I<MUST NOT> call any function that might "block" the
730current coroutine - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or 858current coro - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or
731anything that calls those. Everything else, including calling C<ready>, 859anything that calls those. Everything else, including calling C<ready>,
732works. 860works.
733 861
734=back 862=back
735 863

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