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1=head1 NAME 1=head1 NAME
2 2
3Coro - the real perl threads 3Coro - the only real threads in perl
4 4
5=head1 SYNOPSIS 5=head1 SYNOPSIS
6 6
7 use Coro; 7 use Coro;
8 8
… …
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;
… …
26 $locked = 1; 26 $locked = 1;
27 $lock->up; 27 $lock->up;
28 28
29=head1 DESCRIPTION 29=head1 DESCRIPTION
30 30
31This module collection manages coroutines, that is, cooperative 31For a tutorial-style introduction, please read the L<Coro::Intro>
32threads. Coroutines are similar to kernel threads but don't (in general) 32manpage. This manpage mainly contains reference information.
33
34This module collection manages continuations in general, most often in
35the form of cooperative threads (also called coros, or simply "coro"
36in the documentation). They are similar to kernel threads but don't (in
33run 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
34of coroutine used in this module also guarantees you that it will not 38specific flavor of thread offered by this module also guarantees you that
35switch between coroutines unless necessary, at easily-identified points 39it will not switch between threads unless necessary, at easily-identified
36in your program, so locking and parallel access are rarely an issue, 40points in your program, so locking and parallel access are rarely an
37making coroutine programming much safer and easier than using other thread 41issue, making thread programming much safer and easier than using other
38models. 42thread models.
39 43
40Unlike the so-called "Perl threads" (which are not actually real threads 44Unlike the so-called "Perl threads" (which are not actually real threads
41but only the windows process emulation ported to unix), Coro provides a 45but only the windows process emulation ported to unix, and as such act
42full shared address space, which makes communication between coroutines 46as processes), Coro provides a full shared address space, which makes
43very easy. And coroutines are fast, too: disabling the Windows process 47communication between threads very easy. And Coro's threads are fast,
44emulation 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
45four 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.
46 53
47Coro achieves that by supporting multiple running interpreters that share 54Coro achieves that by supporting multiple running interpreters that share
48data, which is especially useful to code pseudo-parallel processes and 55data, which is especially useful to code pseudo-parallel processes and
49for event-based programming, such as multiple HTTP-GET requests running 56for event-based programming, such as multiple HTTP-GET requests running
50concurrently. 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
51into an event-based environment. 58into an event-based environment.
52 59
53In this module, a coroutines is defined as "callchain + lexical variables 60In this module, a thread is defined as "callchain + lexical variables +
54+ @_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own 61some package variables + C stack), that is, a thread has its own callchain,
55callchain, its own set of lexicals and its own set of perls most important 62its own set of lexicals and its own set of perls most important global
56global variables (see L<Coro::State> for more configuration and background 63variables (see L<Coro::State> for more configuration and background info).
57info).
58 64
59See 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
60module family is quite large. 66module family is quite large.
61 67
62=cut 68=cut
… …
64package Coro; 70package Coro;
65 71
66use strict qw(vars subs); 72use strict qw(vars subs);
67no warnings "uninitialized"; 73no warnings "uninitialized";
68 74
75use Guard ();
76
69use Coro::State; 77use Coro::State;
70 78
71use base qw(Coro::State Exporter); 79use base qw(Coro::State Exporter);
72 80
73our $idle; # idle handler 81our $idle; # idle handler
74our $main; # main coroutine 82our $main; # main coro
75our $current; # current coroutine 83our $current; # current coro
76 84
77our $VERSION = "5.0"; 85our $VERSION = 5.162;
78 86
79our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); 87our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
80our %EXPORT_TAGS = ( 88our %EXPORT_TAGS = (
81 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)],
82); 90);
… …
86 94
87=over 4 95=over 4
88 96
89=item $Coro::main 97=item $Coro::main
90 98
91This variable stores the coroutine object that represents the main 99This variable stores the Coro object that represents the main
92program. While you cna C<ready> it and do most other things you can do to 100program. While you cna C<ready> it and do most other things you can do to
93coroutines, it is mainly useful to compare again C<$Coro::current>, to see 101coro, it is mainly useful to compare again C<$Coro::current>, to see
94whether you are running in the main program or not. 102whether you are running in the main program or not.
95 103
96=cut 104=cut
97 105
98# $main is now being initialised by Coro::State 106# $main is now being initialised by Coro::State
99 107
100=item $Coro::current 108=item $Coro::current
101 109
102The coroutine object representing the current coroutine (the last 110The Coro object representing the current coro (the last
103coroutine that the Coro scheduler switched to). The initial value is 111coro that the Coro scheduler switched to). The initial value is
104C<$Coro::main> (of course). 112C<$Coro::main> (of course).
105 113
106This 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
107value 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
108not otherwise modify the variable itself. 116not otherwise modify the variable itself.
109 117
110=cut 118=cut
111 119
112sub current() { $current } # [DEPRECATED] 120sub current() { $current } # [DEPRECATED]
113 121
114=item $Coro::idle 122=item $Coro::idle
115 123
116This 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
117usually better to rely on L<Coro::AnyEvent> or LC<Coro::EV>, as this is 125usually better to rely on L<Coro::AnyEvent> or L<Coro::EV>, as this is
118pretty low-level functionality. 126pretty low-level functionality.
119 127
120This variable stores a callback that is called whenever the scheduler 128This variable stores either a Coro object or a callback.
129
130If it is a callback, the it is called whenever the scheduler finds no
121finds no ready coroutines to run. The default implementation prints 131ready coros to run. The default implementation prints "FATAL:
122"FATAL: deadlock detected" and exits, because the program has no other way 132deadlock detected" and exits, because the program has no other way to
123to continue. 133continue.
124 134
135If it is a coro object, then this object will be readied (without
136invoking any ready hooks, however) when the scheduler finds no other ready
137coros to run.
138
125This hook is overwritten by modules such as C<Coro::Timer> and 139This hook is overwritten by modules such as C<Coro::EV> and
126C<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
127coroutine so the scheduler can run it. 141coro so the scheduler can run it.
128 142
129Note that the callback I<must not>, under any circumstances, block 143Note that the callback I<must not>, under any circumstances, block
130the current coroutine. Normally, this is achieved by having an "idle 144the current coro. Normally, this is achieved by having an "idle
131coroutine" that calls the event loop and then blocks again, and then 145coro" that calls the event loop and then blocks again, and then
132readying that coroutine in the idle handler. 146readying that coro in the idle handler, or by simply placing the idle
147coro in this variable.
133 148
134See 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
135technique. 150technique.
136 151
137Please 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
… …
142$idle = sub { 157$idle = sub {
143 require Carp; 158 require Carp;
144 Carp::croak ("FATAL: deadlock detected"); 159 Carp::croak ("FATAL: deadlock detected");
145}; 160};
146 161
147# this coroutine is necessary because a coroutine 162# this coro is necessary because a coro
148# cannot destroy itself. 163# cannot destroy itself.
149our @destroy; 164our @destroy;
150our $manager; 165our $manager;
151 166
152$manager = new Coro sub { 167$manager = new Coro sub {
153 while () { 168 while () {
154 Coro::_cancel shift @destroy 169 Coro::State::cancel shift @destroy
155 while @destroy; 170 while @destroy;
156 171
157 &schedule; 172 &schedule;
158 } 173 }
159}; 174};
160$manager->{desc} = "[coro manager]"; 175$manager->{desc} = "[coro manager]";
161$manager->prio (PRIO_MAX); 176$manager->prio (PRIO_MAX);
162 177
163=back 178=back
164 179
165=head1 SIMPLE COROUTINE CREATION 180=head1 SIMPLE CORO CREATION
166 181
167=over 4 182=over 4
168 183
169=item async { ... } [@args...] 184=item async { ... } [@args...]
170 185
171Create a new coroutine and return it's coroutine object (usually 186Create a new coro and return its Coro object (usually
172unused). The coroutine will be put into the ready queue, so 187unused). The coro will be put into the ready queue, so
173it will start running automatically on the next scheduler run. 188it will start running automatically on the next scheduler run.
174 189
175The 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
176coroutine. When it returns argument returns the coroutine is automatically 191coro. When it returns argument returns the coro is automatically
177terminated. 192terminated.
178 193
179The remaining arguments are passed as arguments to the closure. 194The remaining arguments are passed as arguments to the closure.
180 195
181See the C<Coro::State::new> constructor for info about the coroutine 196See the C<Coro::State::new> constructor for info about the coro
182environment in which coroutines are executed. 197environment in which coro are executed.
183 198
184Calling 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
185the coroutine. Likewise, when the coroutine dies, the program will exit, 200the coro. Likewise, when the coro dies, the program will exit,
186just as it would in the main program. 201just as it would in the main program.
187 202
188If 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
189simply avoid dieing (by use of C<eval>). 204simply avoid dieing (by use of C<eval>).
190 205
191Example: Create a new coroutine that just prints its arguments. 206Example: Create a new coro that just prints its arguments.
192 207
193 async { 208 async {
194 print "@_\n"; 209 print "@_\n";
195 } 1,2,3,4; 210 } 1,2,3,4;
196 211
… …
202 $coro 217 $coro
203} 218}
204 219
205=item async_pool { ... } [@args...] 220=item async_pool { ... } [@args...]
206 221
207Similar 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
208terminate 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
209coroutine that might have executed other code already (which can be good 224coro that might have executed other code already (which can be good
210or bad :). 225or bad :).
211 226
212On 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
213destroying) 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
214coroutines in quick successsion, use C<async_pool>, not C<async>. 229coros in quick successsion, use C<async_pool>, not C<async>.
215 230
216The 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
217issued in case of an exception instead of terminating the program, as 232issued in case of an exception instead of terminating the program, as
218C<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>
219will 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,
220which somehow defeats the purpose of pooling (but is fine in the 235which somehow defeats the purpose of pooling (but is fine in the
221exceptional case). 236exceptional case).
222 237
223The 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
224disabled, the description will be reset and the default output filehandle 239disabled, the description will be reset and the default output filehandle
225gets restored, so you can change all these. Otherwise the coroutine will 240gets restored, so you can change all these. Otherwise the coro will
226be 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
227stuff 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
228simply done by using local as in: C<< local $/ >>. 243simply done by using local as in: C<< local $/ >>.
229 244
230The 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
231adjusted 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
232coros as required. 247coros as required.
233 248
234If you are concerned about pooled coroutines growing a lot because a 249If you are concerned about pooled coros growing a lot because a
235single 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
236{ 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
237addition 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
238(adjustable via $Coro::POOL_RSS) it will also be destroyed. 253(adjustable via $Coro::POOL_RSS) it will also be destroyed.
239 254
… …
256=back 271=back
257 272
258=head1 STATIC METHODS 273=head1 STATIC METHODS
259 274
260Static methods are actually functions that implicitly operate on the 275Static methods are actually functions that implicitly operate on the
261current coroutine. 276current coro.
262 277
263=over 4 278=over 4
264 279
265=item schedule 280=item schedule
266 281
267Calls the scheduler. The scheduler will find the next coroutine that is 282Calls the scheduler. The scheduler will find the next coro that is
268to be run from the ready queue and switches to it. The next coroutine 283to be run from the ready queue and switches to it. The next coro
269to be run is simply the one with the highest priority that is longest 284to be run is simply the one with the highest priority that is longest
270in its ready queue. If there is no coroutine ready, it will clal the 285in its ready queue. If there is no coro ready, it will clal the
271C<$Coro::idle> hook. 286C<$Coro::idle> hook.
272 287
273Please 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
274queue, so calling this function usually means you will never be called 289queue, so calling this function usually means you will never be called
275again unless something else (e.g. an event handler) calls C<< ->ready >>, 290again unless something else (e.g. an event handler) calls C<< ->ready >>,
276thus waking you up. 291thus waking you up.
277 292
278This 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
279coroutine and wait for events: first you remember the current coroutine in 294coro and wait for events: first you remember the current coro in
280a 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
281>> 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
282yourself 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,
283so 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
284status in a variable. 299status in a variable.
285 300
286See 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.
287 302
288=item cede 303=item cede
289 304
290"Cede" to other coroutines. This function puts the current coroutine into 305"Cede" to other coros. This function puts the current coro into
291the 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
292up the current "timeslice" to other coroutines of the same or higher 307up the current "timeslice" to other coros of the same or higher
293priority. Once your coroutine gets its turn again it will automatically be 308priority. Once your coro gets its turn again it will automatically be
294resumed. 309resumed.
295 310
296This function is often called C<yield> in other languages. 311This function is often called C<yield> in other languages.
297 312
298=item Coro::cede_notself 313=item Coro::cede_notself
299 314
300Works 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>
301coroutine, regardless of priority. This is useful sometimes to ensure 316coro, regardless of priority. This is useful sometimes to ensure
302progress is made. 317progress is made.
303 318
304=item terminate [arg...] 319=item terminate [arg...]
305 320
306Terminates 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
307 408
308=item killall 409=item killall
309 410
310Kills/terminates/cancels all coroutines except the currently running 411Kills/terminates/cancels all coros except the currently running one.
311one. This is useful after a fork, either in the child or the parent, as
312usually only one of them should inherit the running coroutines.
313 412
314Note 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
315you 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
316program calls this function, there will be some one-time resource leak. 416calls this function, there will be some one-time resource leak.
317 417
318=cut 418=cut
319 419
320sub killall { 420sub killall {
321 for (Coro::State::list) { 421 for (Coro::State::list) {
… …
324 } 424 }
325} 425}
326 426
327=back 427=back
328 428
329=head1 COROUTINE OBJECT METHODS 429=head1 CORO OBJECT METHODS
330 430
331These 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
332them). 432them).
333 433
334=over 4 434=over 4
335 435
336=item new Coro \&sub [, @args...] 436=item new Coro \&sub [, @args...]
337 437
338Create 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
339automatically terminates as if C<terminate> with the returned values were 439automatically terminates as if C<terminate> with the returned values were
340called. 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
341queue by calling the ready method. 441queue by calling the ready method.
342 442
343See 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
344coroutine environment. 444coro environment.
345 445
346=cut 446=cut
347 447
348sub _terminate { 448sub _coro_run {
349 terminate &{+shift}; 449 terminate &{+shift};
350} 450}
351 451
352=item $success = $coroutine->ready 452=item $success = $coro->ready
353 453
354Put 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
355queue 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
356the ready queue, do nothing and return false. 456the ready queue, do nothing and return false.
357 457
358This ensures that the scheduler will resume this coroutine automatically 458This ensures that the scheduler will resume this coro automatically
359once 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
360priority that were put into the ready queue earlier have been resumed. 460priority that were put into the ready queue earlier have been resumed.
361 461
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
362=item $is_ready = $coroutine->is_ready 487=item $is_ready = $coro->is_ready
363 488
364Return 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.
365 491
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
366=item $coroutine->cancel (arg...) 503=item $coro->cancel (arg...)
367 504
368Terminates the given coroutine and makes it return the given arguments as 505Terminates the given Coro and makes it return the given arguments as
369status (default: the empty list). Never returns if the coroutine is the 506status (default: the empty list). Never returns if the Coro is the
370current coroutine. 507current Coro.
371 508
372=cut 509=cut
373 510
374sub cancel { 511sub cancel {
375 my $self = shift; 512 my $self = shift;
376 513
377 if ($current == $self) { 514 if ($current == $self) {
378 terminate @_; 515 terminate @_;
379 } else { 516 } else {
380 $self->{_status} = [@_]; 517 $self->{_status} = [@_];
381 $self->_cancel; 518 Coro::State::cancel $self;
382 } 519 }
383} 520}
384 521
385=item $coroutine->schedule_to 522=item $coro->schedule_to
386 523
387Puts the current coroutine to sleep (like C<Coro::schedule>), but instead 524Puts the current coro to sleep (like C<Coro::schedule>), but instead
388of 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
389the given coroutine object (regardless of priority etc.). The readyness 526the given coro object (regardless of priority etc.). The readyness
390state of that coroutine isn't changed. 527state of that coro isn't changed.
391 528
392This 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
393uses for this one. 530uses for this one.
394 531
395=item $coroutine->cede_to 532=item $coro->cede_to
396 533
397Like C<schedule_to>, but puts the current coroutine into the ready 534Like C<schedule_to>, but puts the current coro into the ready
398queue. This has the effect of temporarily switching to the given 535queue. This has the effect of temporarily switching to the given
399coroutine, and continuing some time later. 536coro, and continuing some time later.
400 537
401This 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
402uses for this one. 539uses for this one.
403 540
404=item $coroutine->throw ([$scalar]) 541=item $coro->throw ([$scalar])
405 542
406If 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
407inside the coroutine at the next convenient point in time. Otherwise 544inside the coro at the next convenient point in time. Otherwise
408clears the exception object. 545clears the exception object.
409 546
410Coro will check for the exception each time a schedule-like-function 547Coro will check for the exception each time a schedule-like-function
411returns, 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
412>>, C<< Coro::Handle->readable >> and so on. Most of these functions 549>>, C<< Coro::Handle->readable >> and so on. Most of these functions
… …
414 551
415The 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
416C<$@>, i.e. if it is a string, no line number or newline will be appended 553C<$@>, i.e. if it is a string, no line number or newline will be appended
417(unlike with C<die>). 554(unlike with C<die>).
418 555
419This 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
420end 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
421termination, 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
422program. 559program.
423 560
424You 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
425C<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).
426 563
427=item $coroutine->join 564=item $coro->join
428 565
429Wait until the coroutine terminates and return any values given to the 566Wait until the coro terminates and return any values given to the
430C<terminate> or C<cancel> functions. C<join> can be called concurrently 567C<terminate> or C<cancel> functions. C<join> can be called concurrently
431from multiple coroutines, and all will be resumed and given the status 568from multiple coro, and all will be resumed and given the status
432return once the C<$coroutine> terminates. 569return once the C<$coro> terminates.
433 570
434=cut 571=cut
435 572
436sub join { 573sub join {
437 my $self = shift; 574 my $self = shift;
… …
448 } 585 }
449 586
450 wantarray ? @{$self->{_status}} : $self->{_status}[0]; 587 wantarray ? @{$self->{_status}} : $self->{_status}[0];
451} 588}
452 589
453=item $coroutine->on_destroy (\&cb) 590=item $coro->on_destroy (\&cb)
454 591
455Registers a callback that is called when this coroutine gets destroyed, 592Registers a callback that is called when this coro gets destroyed,
456but before it is joined. The callback gets passed the terminate arguments, 593but before it is joined. The callback gets passed the terminate arguments,
457if any, and I<must not> die, under any circumstances. 594if any, and I<must not> die, under any circumstances.
458 595
459=cut 596=cut
460 597
… …
462 my ($self, $cb) = @_; 599 my ($self, $cb) = @_;
463 600
464 push @{ $self->{_on_destroy} }, $cb; 601 push @{ $self->{_on_destroy} }, $cb;
465} 602}
466 603
467=item $oldprio = $coroutine->prio ($newprio) 604=item $oldprio = $coro->prio ($newprio)
468 605
469Sets (or gets, if the argument is missing) the priority of the 606Sets (or gets, if the argument is missing) the priority of the
470coroutine. Higher priority coroutines get run before lower priority 607coro. Higher priority coro get run before lower priority
471coroutines. Priorities are small signed integers (currently -4 .. +3), 608coro. Priorities are small signed integers (currently -4 .. +3),
472that 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
473to get then): 610to get then):
474 611
475 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
476 3 > 1 > 0 > -1 > -3 > -4 613 3 > 1 > 0 > -1 > -3 > -4
477 614
478 # set priority to HIGH 615 # set priority to HIGH
479 current->prio(PRIO_HIGH); 616 current->prio (PRIO_HIGH);
480 617
481The idle coroutine ($Coro::idle) always has a lower priority than any 618The idle coro ($Coro::idle) always has a lower priority than any
482existing coroutine. 619existing coro.
483 620
484Changing the priority of the current coroutine will take effect immediately, 621Changing the priority of the current coro will take effect immediately,
485but changing the priority of coroutines in the ready queue (but not 622but changing the priority of coro in the ready queue (but not
486running) will only take effect after the next schedule (of that 623running) will only take effect after the next schedule (of that
487coroutine). 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.
488 625
489=item $newprio = $coroutine->nice ($change) 626=item $newprio = $coro->nice ($change)
490 627
491Similar 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.
492higher values mean lower priority, just as in unix). 629higher values mean lower priority, just as in unix).
493 630
494=item $olddesc = $coroutine->desc ($newdesc) 631=item $olddesc = $coro->desc ($newdesc)
495 632
496Sets (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
497coroutine. 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
498coroutine. 635coro.
499 636
500This method simply sets the C<< $coroutine->{desc} >> member to the given 637This method simply sets the C<< $coro->{desc} >> member to the given
501string. You can modify this member directly if you wish. 638string. You can modify this member directly if you wish.
502 639
503=cut 640=cut
504 641
505sub desc { 642sub desc {
… …
519 656
520=over 4 657=over 4
521 658
522=item Coro::nready 659=item Coro::nready
523 660
524Returns the number of coroutines that are currently in the ready state, 661Returns the number of coro that are currently in the ready state,
525i.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
526indirectly. 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
527currently 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>
528would 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
529coroutines. 666coro.
530 667
531=item my $guard = Coro::guard { ... } 668=item my $guard = Coro::guard { ... }
532 669
533This creates and returns a guard object. Nothing happens until the object 670This function still exists, but is deprecated. Please use the
534gets destroyed, in which case the codeblock given as argument will be 671C<Guard::guard> function instead.
535executed. This is useful to free locks or other resources in case of a
536runtime error or when the coroutine gets canceled, as in both cases the
537guard block will be executed. The guard object supports only one method,
538C<< ->cancel >>, which will keep the codeblock from being executed.
539 672
540Example: set some flag and clear it again when the coroutine gets canceled
541or the function returns:
542
543 sub do_something {
544 my $guard = Coro::guard { $busy = 0 };
545 $busy = 1;
546
547 # do something that requires $busy to be true
548 }
549
550=cut 673=cut
551 674
552sub guard(&) { 675BEGIN { *guard = \&Guard::guard }
553 bless \(my $cb = $_[0]), "Coro::guard"
554}
555
556sub Coro::guard::cancel {
557 ${$_[0]} = sub { };
558}
559
560sub Coro::guard::DESTROY {
561 ${$_[0]}->();
562}
563
564 676
565=item unblock_sub { ... } 677=item unblock_sub { ... }
566 678
567This utility function takes a BLOCK or code reference and "unblocks" it, 679This utility function takes a BLOCK or code reference and "unblocks" it,
568returning a new coderef. Unblocking means that calling the new coderef 680returning a new coderef. Unblocking means that calling the new coderef
569will return immediately without blocking, returning nothing, while the 681will return immediately without blocking, returning nothing, while the
570original code ref will be called (with parameters) from within another 682original code ref will be called (with parameters) from within another
571coroutine. 683coro.
572 684
573The 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
574venerable L<Event|Event> module) are not coroutine-safe (a weaker form 686venerable L<Event|Event> module) are not thread-safe (a weaker form
575of thread-safety). This means you must not block within event callbacks, 687of reentrancy). This means you must not block within event callbacks,
576otherwise you might suffer from crashes or worse. The only event library 688otherwise you might suffer from crashes or worse. The only event library
577currently 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>.
578 690
579This function allows your callbacks to block by executing them in another 691This function allows your callbacks to block by executing them in another
580coroutine 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
581is 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
582disk, for example. 694disk, for example.
583 695
584In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when 696In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
585creating event callbacks that want to block. 697creating event callbacks that want to block.
586 698
587If 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
588another coroutine, or puts some other coroutine into the ready queue), 700another coro, or puts some other coro into the ready queue), there is
589there is no reason to use C<unblock_sub>. 701no reason to use C<unblock_sub>.
590 702
591Note 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
592are 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
593use 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
594provides callbacks that are the result of some event callback, then you 706provides callbacks that are the result of some event callback, then you
… …
626 } 738 }
627} 739}
628 740
629=item $cb = Coro::rouse_cb 741=item $cb = Coro::rouse_cb
630 742
631Create and return a "rouse callback". That's a code reference that, when 743Create and return a "rouse callback". That's a code reference that,
632called, will save its arguments and notify the owner coroutine of the 744when called, will remember a copy of its arguments and notify the owner
633callback. 745coro of the callback.
634 746
635See the next function. 747See the next function.
636 748
637=item @args = Coro::rouse_wait [$cb] 749=item @args = Coro::rouse_wait [$cb]
638 750
639Wait for the specified rouse callback (or the last one tht was created in 751Wait for the specified rouse callback (or the last one that was created in
640this coroutine). 752this coro).
641 753
642As soon as the callback is invoked (or when the calback was invoked before 754As soon as the callback is invoked (or when the callback was invoked
643C<rouse_wait>), it will return a copy of the arguments originally passed 755before C<rouse_wait>), it will return the arguments originally passed to
644to the rouse callback. 756the rouse callback. In scalar context, that means you get the I<last>
757argument, just as if C<rouse_wait> had a C<return ($a1, $a2, $a3...)>
758statement at the end.
645 759
646See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example. 760See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example.
647 761
648=back 762=back
649 763
… …
651 765
6521; 7661;
653 767
654=head1 HOW TO WAIT FOR A CALLBACK 768=head1 HOW TO WAIT FOR A CALLBACK
655 769
656It is very common for a coroutine to wait for some callback to be 770It is very common for a coro to wait for some callback to be
657called. This occurs naturally when you use coroutines in an otherwise 771called. This occurs naturally when you use coro in an otherwise
658event-based program, or when you use event-based libraries. 772event-based program, or when you use event-based libraries.
659 773
660These typically register a callback for some event, and call that callback 774These typically register a callback for some event, and call that callback
661when the event occured. In a coroutine, however, you typically want to 775when the event occured. In a coro, however, you typically want to
662just wait for the event, simplyifying things. 776just wait for the event, simplyifying things.
663 777
664For example C<< AnyEvent->child >> registers a callback to be called when 778For example C<< AnyEvent->child >> registers a callback to be called when
665a specific child has exited: 779a specific child has exited:
666 780
667 my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... }); 781 my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... });
668 782
669But from withina coroutine, you often just want to write this: 783But from within a coro, you often just want to write this:
670 784
671 my $status = wait_for_child $pid; 785 my $status = wait_for_child $pid;
672 786
673Coro offers two functions specifically designed to make this easy, 787Coro offers two functions specifically designed to make this easy,
674C<Coro::rouse_cb> and C<Coro::rouse_wait>. 788C<Coro::rouse_cb> and C<Coro::rouse_wait>.
675 789
676The first function, C<rouse_cb>, generates and returns a callback that, 790The first function, C<rouse_cb>, generates and returns a callback that,
677when invoked, will save it's arguments and notify the coroutine that 791when invoked, will save its arguments and notify the coro that
678created the callback. 792created the callback.
679 793
680The second function, C<rouse_wait>, waits for the callback to be called 794The second function, C<rouse_wait>, waits for the callback to be called
681(by calling C<schedule> to go to sleep) and returns the arguments 795(by calling C<schedule> to go to sleep) and returns the arguments
682originally passed to the callback. 796originally passed to the callback.
… …
697you can roll your own, using C<schedule>: 811you can roll your own, using C<schedule>:
698 812
699 sub wait_for_child($) { 813 sub wait_for_child($) {
700 my ($pid) = @_; 814 my ($pid) = @_;
701 815
702 # store the current coroutine in $current, 816 # store the current coro in $current,
703 # and provide result variables for the closure passed to ->child 817 # and provide result variables for the closure passed to ->child
704 my $current = $Coro::current; 818 my $current = $Coro::current;
705 my ($done, $rstatus); 819 my ($done, $rstatus);
706 820
707 # pass a closure to ->child 821 # pass a closure to ->child
… …
723 837
724=item fork with pthread backend 838=item fork with pthread backend
725 839
726When Coro is compiled using the pthread backend (which isn't recommended 840When Coro is compiled using the pthread backend (which isn't recommended
727but required on many BSDs as their libcs are completely broken), then 841but required on many BSDs as their libcs are completely broken), then
728coroutines will not survive a fork. There is no known workaround except to 842coro will not survive a fork. There is no known workaround except to
729fix your libc and use a saner backend. 843fix your libc and use a saner backend.
730 844
731=item perl process emulation ("threads") 845=item perl process emulation ("threads")
732 846
733This module is not perl-pseudo-thread-safe. You should only ever use this 847This module is not perl-pseudo-thread-safe. You should only ever use this
734module from the same thread (this requirement might be removed in the 848module from the first thread (this requirement might be removed in the
735future to allow per-thread schedulers, but Coro::State does not yet allow 849future to allow per-thread schedulers, but Coro::State does not yet allow
736this). I recommend disabling thread support and using processes, as having 850this). I recommend disabling thread support and using processes, as having
737the windows process emulation enabled under unix roughly halves perl 851the windows process emulation enabled under unix roughly halves perl
738performance, even when not used. 852performance, even when not used.
739 853
740=item coroutine switching not signal safe 854=item coro switching is not signal safe
741 855
742You must not switch to another coroutine from within a signal handler 856You must not switch to another coro from within a signal handler
743(only relevant with %SIG - most event libraries provide safe signals). 857(only relevant with %SIG - most event libraries provide safe signals).
744 858
745That means you I<MUST NOT> call any function that might "block" the 859That means you I<MUST NOT> call any function that might "block" the
746current coroutine - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or 860current coro - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or
747anything that calls those. Everything else, including calling C<ready>, 861anything that calls those. Everything else, including calling C<ready>,
748works. 862works.
749 863
750=back 864=back
751 865
… …
756 870
757Debugging: L<Coro::Debug>. 871Debugging: L<Coro::Debug>.
758 872
759Support/Utility: L<Coro::Specific>, L<Coro::Util>. 873Support/Utility: L<Coro::Specific>, L<Coro::Util>.
760 874
761Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>. 875Locking and IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>,
876L<Coro::SemaphoreSet>, L<Coro::RWLock>.
762 877
763IO/Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>. 878I/O and Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>.
764 879
765Compatibility: L<Coro::LWP>, L<Coro::BDB>, L<Coro::Storable>, L<Coro::Select>. 880Compatibility with other modules: L<Coro::LWP> (but see also L<AnyEvent::HTTP> for
881a better-working alternative), L<Coro::BDB>, L<Coro::Storable>,
882L<Coro::Select>.
766 883
767XS API: L<Coro::MakeMaker>. 884XS API: L<Coro::MakeMaker>.
768 885
769Low level Configuration, Coroutine Environment: L<Coro::State>. 886Low level Configuration, Thread Environment, Continuations: L<Coro::State>.
770 887
771=head1 AUTHOR 888=head1 AUTHOR
772 889
773 Marc Lehmann <schmorp@schmorp.de> 890 Marc Lehmann <schmorp@schmorp.de>
774 http://home.schmorp.de/ 891 http://home.schmorp.de/

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