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1=head1 NAME 1=head1 NAME
2 2
3Coro - real threads in perl 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;
… …
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 coroutines, that is, cooperative 34This module collection manages continuations in general, most often in
35threads. Coroutines are similar to kernel threads but don't (in general) 35the form of cooperative threads (also called coros, or simply "coro"
36in the documentation). They are similar to kernel threads but don't (in
36run 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
37of coroutine used in this module also guarantees you that it will not 38specific flavor of thread offered by this module also guarantees you that
38switch between coroutines unless necessary, at easily-identified points 39it will not switch between threads unless necessary, at easily-identified
39in your program, so locking and parallel access are rarely an issue, 40points in your program, so locking and parallel access are rarely an
40making coroutine programming much safer and easier than using other thread 41issue, making thread programming much safer and easier than using other
41models. 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 coroutines 46as processes), Coro provides a full shared address space, which makes
46very easy. And coroutines 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 coroutines is defined as "callchain + lexical variables 60In this module, a thread is defined as "callchain + lexical variables +
57+ @_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own 61some package variables + C stack), that is, a thread has its own callchain,
58callchain, 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
59global variables (see L<Coro::State> for more configuration and background 63variables (see L<Coro::State> for more configuration and background info).
60info).
61 64
62See 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
63module family is quite large. 66module family is quite large.
64 67
65=cut 68=cut
… …
67package Coro; 70package Coro;
68 71
69use strict qw(vars subs); 72use strict qw(vars subs);
70no warnings "uninitialized"; 73no warnings "uninitialized";
71 74
75use Guard ();
76
72use Coro::State; 77use Coro::State;
73 78
74use base qw(Coro::State Exporter); 79use base qw(Coro::State Exporter);
75 80
76our $idle; # idle handler 81our $idle; # idle handler
77our $main; # main coroutine 82our $main; # main coro
78our $current; # current coroutine 83our $current; # current coro
79 84
80our $VERSION = "5.0"; 85our $VERSION = 5.15;
81 86
82our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); 87our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
83our %EXPORT_TAGS = ( 88our %EXPORT_TAGS = (
84 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)],
85); 90);
… …
89 94
90=over 4 95=over 4
91 96
92=item $Coro::main 97=item $Coro::main
93 98
94This variable stores the coroutine object that represents the main 99This variable stores the Coro object that represents the main
95program. While you cna C<ready> it and do most other things you can do to 100program. While you cna C<ready> it and do most other things you can do to
96coroutines, it is mainly useful to compare again C<$Coro::current>, to see 101coro, it is mainly useful to compare again C<$Coro::current>, to see
97whether you are running in the main program or not. 102whether you are running in the main program or not.
98 103
99=cut 104=cut
100 105
101# $main is now being initialised by Coro::State 106# $main is now being initialised by Coro::State
102 107
103=item $Coro::current 108=item $Coro::current
104 109
105The coroutine object representing the current coroutine (the last 110The Coro object representing the current coro (the last
106coroutine that the Coro scheduler switched to). The initial value is 111coro that the Coro scheduler switched to). The initial value is
107C<$Coro::main> (of course). 112C<$Coro::main> (of course).
108 113
109This 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
110value 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
111not otherwise modify the variable itself. 116not otherwise modify the variable itself.
112 117
113=cut 118=cut
114 119
115sub current() { $current } # [DEPRECATED] 120sub current() { $current } # [DEPRECATED]
116 121
117=item $Coro::idle 122=item $Coro::idle
118 123
119This 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
120usually 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
121pretty low-level functionality. 126pretty low-level functionality.
122 127
123This 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
124finds no ready coroutines to run. The default implementation prints 131ready coros to run. The default implementation prints "FATAL:
125"FATAL: deadlock detected" and exits, because the program has no other way 132deadlock detected" and exits, because the program has no other way to
126to continue. 133continue.
127 134
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
128This hook is overwritten by modules such as C<Coro::Timer> and 139This hook is overwritten by modules such as C<Coro::EV> and
129C<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
130coroutine so the scheduler can run it. 141coro so the scheduler can run it.
131 142
132Note that the callback I<must not>, under any circumstances, block 143Note that the callback I<must not>, under any circumstances, block
133the current coroutine. Normally, this is achieved by having an "idle 144the current coro. Normally, this is achieved by having an "idle
134coroutine" that calls the event loop and then blocks again, and then 145coro" that calls the event loop and then blocks again, and then
135readying that coroutine in the idle handler. 146readying that coro in the idle handler, or by simply placing the idle
147coro in this variable.
136 148
137See 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
138technique. 150technique.
139 151
140Please 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
… …
145$idle = sub { 157$idle = sub {
146 require Carp; 158 require Carp;
147 Carp::croak ("FATAL: deadlock detected"); 159 Carp::croak ("FATAL: deadlock detected");
148}; 160};
149 161
150# this coroutine is necessary because a coroutine 162# this coro is necessary because a coro
151# cannot destroy itself. 163# cannot destroy itself.
152our @destroy; 164our @destroy;
153our $manager; 165our $manager;
154 166
155$manager = new Coro sub { 167$manager = new Coro sub {
156 while () { 168 while () {
157 Coro::_cancel shift @destroy 169 Coro::State::cancel shift @destroy
158 while @destroy; 170 while @destroy;
159 171
160 &schedule; 172 &schedule;
161 } 173 }
162}; 174};
163$manager->{desc} = "[coro manager]"; 175$manager->{desc} = "[coro manager]";
164$manager->prio (PRIO_MAX); 176$manager->prio (PRIO_MAX);
165 177
166=back 178=back
167 179
168=head1 SIMPLE COROUTINE CREATION 180=head1 SIMPLE CORO CREATION
169 181
170=over 4 182=over 4
171 183
172=item async { ... } [@args...] 184=item async { ... } [@args...]
173 185
174Create a new coroutine and return it's coroutine object (usually 186Create a new coro and return its Coro object (usually
175unused). The coroutine will be put into the ready queue, so 187unused). The coro will be put into the ready queue, so
176it will start running automatically on the next scheduler run. 188it will start running automatically on the next scheduler run.
177 189
178The 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
179coroutine. When it returns argument returns the coroutine is automatically 191coro. When it returns argument returns the coro is automatically
180terminated. 192terminated.
181 193
182The remaining arguments are passed as arguments to the closure. 194The remaining arguments are passed as arguments to the closure.
183 195
184See the C<Coro::State::new> constructor for info about the coroutine 196See the C<Coro::State::new> constructor for info about the coro
185environment in which coroutines are executed. 197environment in which coro are executed.
186 198
187Calling 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
188the coroutine. Likewise, when the coroutine dies, the program will exit, 200the coro. Likewise, when the coro dies, the program will exit,
189just as it would in the main program. 201just as it would in the main program.
190 202
191If 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
192simply avoid dieing (by use of C<eval>). 204simply avoid dieing (by use of C<eval>).
193 205
194Example: Create a new coroutine that just prints its arguments. 206Example: Create a new coro that just prints its arguments.
195 207
196 async { 208 async {
197 print "@_\n"; 209 print "@_\n";
198 } 1,2,3,4; 210 } 1,2,3,4;
199 211
… …
205 $coro 217 $coro
206} 218}
207 219
208=item async_pool { ... } [@args...] 220=item async_pool { ... } [@args...]
209 221
210Similar 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
211terminate 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
212coroutine that might have executed other code already (which can be good 224coro that might have executed other code already (which can be good
213or bad :). 225or bad :).
214 226
215On 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
216destroying) 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
217coroutines in quick successsion, use C<async_pool>, not C<async>. 229coros in quick successsion, use C<async_pool>, not C<async>.
218 230
219The 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
220issued in case of an exception instead of terminating the program, as 232issued in case of an exception instead of terminating the program, as
221C<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>
222will 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,
223which somehow defeats the purpose of pooling (but is fine in the 235which somehow defeats the purpose of pooling (but is fine in the
224exceptional case). 236exceptional case).
225 237
226The 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
227disabled, the description will be reset and the default output filehandle 239disabled, the description will be reset and the default output filehandle
228gets restored, so you can change all these. Otherwise the coroutine will 240gets restored, so you can change all these. Otherwise the coro will
229be 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
230stuff 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
231simply done by using local as in: C<< local $/ >>. 243simply done by using local as in: C<< local $/ >>.
232 244
233The 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
234adjusted 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
235coros as required. 247coros as required.
236 248
237If you are concerned about pooled coroutines growing a lot because a 249If you are concerned about pooled coros growing a lot because a
238single 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
239{ 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
240addition 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
241(adjustable via $Coro::POOL_RSS) it will also be destroyed. 253(adjustable via $Coro::POOL_RSS) it will also be destroyed.
242 254
… …
259=back 271=back
260 272
261=head1 STATIC METHODS 273=head1 STATIC METHODS
262 274
263Static methods are actually functions that implicitly operate on the 275Static methods are actually functions that implicitly operate on the
264current coroutine. 276current coro.
265 277
266=over 4 278=over 4
267 279
268=item schedule 280=item schedule
269 281
270Calls the scheduler. The scheduler will find the next coroutine that is 282Calls the scheduler. The scheduler will find the next coro that is
271to be run from the ready queue and switches to it. The next coroutine 283to be run from the ready queue and switches to it. The next coro
272to be run is simply the one with the highest priority that is longest 284to be run is simply the one with the highest priority that is longest
273in its ready queue. If there is no coroutine ready, it will clal the 285in its ready queue. If there is no coro ready, it will clal the
274C<$Coro::idle> hook. 286C<$Coro::idle> hook.
275 287
276Please 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
277queue, so calling this function usually means you will never be called 289queue, so calling this function usually means you will never be called
278again unless something else (e.g. an event handler) calls C<< ->ready >>, 290again unless something else (e.g. an event handler) calls C<< ->ready >>,
279thus waking you up. 291thus waking you up.
280 292
281This 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
282coroutine and wait for events: first you remember the current coroutine in 294coro and wait for events: first you remember the current coro in
283a 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
284>> 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
285yourself 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,
286so 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
287status in a variable. 299status in a variable.
288 300
289See 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.
290 302
291=item cede 303=item cede
292 304
293"Cede" to other coroutines. This function puts the current coroutine into 305"Cede" to other coros. This function puts the current coro into
294the 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
295up the current "timeslice" to other coroutines of the same or higher 307up the current "timeslice" to other coros of the same or higher
296priority. Once your coroutine gets its turn again it will automatically be 308priority. Once your coro gets its turn again it will automatically be
297resumed. 309resumed.
298 310
299This function is often called C<yield> in other languages. 311This function is often called C<yield> in other languages.
300 312
301=item Coro::cede_notself 313=item Coro::cede_notself
302 314
303Works 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>
304coroutine, regardless of priority. This is useful sometimes to ensure 316coro, regardless of priority. This is useful sometimes to ensure
305progress is made. 317progress is made.
306 318
307=item terminate [arg...] 319=item terminate [arg...]
308 320
309Terminates 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
310 408
311=item killall 409=item killall
312 410
313Kills/terminates/cancels all coroutines except the currently running 411Kills/terminates/cancels all coros except the currently running one.
314one. This is useful after a fork, either in the child or the parent, as
315usually only one of them should inherit the running coroutines.
316 412
317Note 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
318you 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
319program calls this function, there will be some one-time resource leak. 416calls this function, there will be some one-time resource leak.
320 417
321=cut 418=cut
322 419
323sub killall { 420sub killall {
324 for (Coro::State::list) { 421 for (Coro::State::list) {
… …
327 } 424 }
328} 425}
329 426
330=back 427=back
331 428
332=head1 COROUTINE OBJECT METHODS 429=head1 CORO OBJECT METHODS
333 430
334These 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
335them). 432them).
336 433
337=over 4 434=over 4
338 435
339=item new Coro \&sub [, @args...] 436=item new Coro \&sub [, @args...]
340 437
341Create 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
342automatically terminates as if C<terminate> with the returned values were 439automatically terminates as if C<terminate> with the returned values were
343called. 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
344queue by calling the ready method. 441queue by calling the ready method.
345 442
346See 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
347coroutine environment. 444coro environment.
348 445
349=cut 446=cut
350 447
351sub _terminate { 448sub _coro_run {
352 terminate &{+shift}; 449 terminate &{+shift};
353} 450}
354 451
355=item $success = $coroutine->ready 452=item $success = $coro->ready
356 453
357Put 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
358queue 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
359the ready queue, do nothing and return false. 456the ready queue, do nothing and return false.
360 457
361This ensures that the scheduler will resume this coroutine automatically 458This ensures that the scheduler will resume this coro automatically
362once 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
363priority that were put into the ready queue earlier have been resumed. 460priority that were put into the ready queue earlier have been resumed.
364 461
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
365=item $is_ready = $coroutine->is_ready 487=item $is_ready = $coro->is_ready
366 488
367Return 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.
368 491
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
369=item $coroutine->cancel (arg...) 503=item $coro->cancel (arg...)
370 504
371Terminates the given coroutine and makes it return the given arguments as 505Terminates the given Coro and makes it return the given arguments as
372status (default: the empty list). Never returns if the coroutine is the 506status (default: the empty list). Never returns if the Coro is the
373current coroutine. 507current Coro.
374 508
375=cut 509=cut
376 510
377sub cancel { 511sub cancel {
378 my $self = shift; 512 my $self = shift;
379 513
380 if ($current == $self) { 514 if ($current == $self) {
381 terminate @_; 515 terminate @_;
382 } else { 516 } else {
383 $self->{_status} = [@_]; 517 $self->{_status} = [@_];
384 $self->_cancel; 518 Coro::State::cancel $self;
385 } 519 }
386} 520}
387 521
388=item $coroutine->schedule_to 522=item $coro->schedule_to
389 523
390Puts the current coroutine to sleep (like C<Coro::schedule>), but instead 524Puts the current coro to sleep (like C<Coro::schedule>), but instead
391of 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
392the given coroutine object (regardless of priority etc.). The readyness 526the given coro object (regardless of priority etc.). The readyness
393state of that coroutine isn't changed. 527state of that coro isn't changed.
394 528
395This 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
396uses for this one. 530uses for this one.
397 531
398=item $coroutine->cede_to 532=item $coro->cede_to
399 533
400Like C<schedule_to>, but puts the current coroutine into the ready 534Like C<schedule_to>, but puts the current coro into the ready
401queue. This has the effect of temporarily switching to the given 535queue. This has the effect of temporarily switching to the given
402coroutine, and continuing some time later. 536coro, and continuing some time later.
403 537
404This 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
405uses for this one. 539uses for this one.
406 540
407=item $coroutine->throw ([$scalar]) 541=item $coro->throw ([$scalar])
408 542
409If 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
410inside the coroutine at the next convenient point in time. Otherwise 544inside the coro at the next convenient point in time. Otherwise
411clears the exception object. 545clears the exception object.
412 546
413Coro will check for the exception each time a schedule-like-function 547Coro will check for the exception each time a schedule-like-function
414returns, 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
415>>, C<< Coro::Handle->readable >> and so on. Most of these functions 549>>, C<< Coro::Handle->readable >> and so on. Most of these functions
… …
417 551
418The 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
419C<$@>, i.e. if it is a string, no line number or newline will be appended 553C<$@>, i.e. if it is a string, no line number or newline will be appended
420(unlike with C<die>). 554(unlike with C<die>).
421 555
422This 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
423end 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
424termination, 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
425program. 559program.
426 560
427You 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
428C<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).
429 563
430=item $coroutine->join 564=item $coro->join
431 565
432Wait until the coroutine terminates and return any values given to the 566Wait until the coro terminates and return any values given to the
433C<terminate> or C<cancel> functions. C<join> can be called concurrently 567C<terminate> or C<cancel> functions. C<join> can be called concurrently
434from multiple coroutines, and all will be resumed and given the status 568from multiple coro, and all will be resumed and given the status
435return once the C<$coroutine> terminates. 569return once the C<$coro> terminates.
436 570
437=cut 571=cut
438 572
439sub join { 573sub join {
440 my $self = shift; 574 my $self = shift;
… …
451 } 585 }
452 586
453 wantarray ? @{$self->{_status}} : $self->{_status}[0]; 587 wantarray ? @{$self->{_status}} : $self->{_status}[0];
454} 588}
455 589
456=item $coroutine->on_destroy (\&cb) 590=item $coro->on_destroy (\&cb)
457 591
458Registers a callback that is called when this coroutine gets destroyed, 592Registers a callback that is called when this coro gets destroyed,
459but before it is joined. The callback gets passed the terminate arguments, 593but before it is joined. The callback gets passed the terminate arguments,
460if any, and I<must not> die, under any circumstances. 594if any, and I<must not> die, under any circumstances.
461 595
462=cut 596=cut
463 597
… …
465 my ($self, $cb) = @_; 599 my ($self, $cb) = @_;
466 600
467 push @{ $self->{_on_destroy} }, $cb; 601 push @{ $self->{_on_destroy} }, $cb;
468} 602}
469 603
470=item $oldprio = $coroutine->prio ($newprio) 604=item $oldprio = $coro->prio ($newprio)
471 605
472Sets (or gets, if the argument is missing) the priority of the 606Sets (or gets, if the argument is missing) the priority of the
473coroutine. Higher priority coroutines get run before lower priority 607coro. Higher priority coro get run before lower priority
474coroutines. Priorities are small signed integers (currently -4 .. +3), 608coro. Priorities are small signed integers (currently -4 .. +3),
475that 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
476to get then): 610to get then):
477 611
478 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
479 3 > 1 > 0 > -1 > -3 > -4 613 3 > 1 > 0 > -1 > -3 > -4
480 614
481 # set priority to HIGH 615 # set priority to HIGH
482 current->prio(PRIO_HIGH); 616 current->prio (PRIO_HIGH);
483 617
484The idle coroutine ($Coro::idle) always has a lower priority than any 618The idle coro ($Coro::idle) always has a lower priority than any
485existing coroutine. 619existing coro.
486 620
487Changing the priority of the current coroutine will take effect immediately, 621Changing the priority of the current coro will take effect immediately,
488but changing the priority of coroutines in the ready queue (but not 622but changing the priority of coro in the ready queue (but not
489running) will only take effect after the next schedule (of that 623running) will only take effect after the next schedule (of that
490coroutine). 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.
491 625
492=item $newprio = $coroutine->nice ($change) 626=item $newprio = $coro->nice ($change)
493 627
494Similar 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.
495higher values mean lower priority, just as in unix). 629higher values mean lower priority, just as in unix).
496 630
497=item $olddesc = $coroutine->desc ($newdesc) 631=item $olddesc = $coro->desc ($newdesc)
498 632
499Sets (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
500coroutine. 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
501coroutine. 635coro.
502 636
503This method simply sets the C<< $coroutine->{desc} >> member to the given 637This method simply sets the C<< $coro->{desc} >> member to the given
504string. You can modify this member directly if you wish. 638string. You can modify this member directly if you wish.
505 639
506=cut 640=cut
507 641
508sub desc { 642sub desc {
… …
522 656
523=over 4 657=over 4
524 658
525=item Coro::nready 659=item Coro::nready
526 660
527Returns the number of coroutines that are currently in the ready state, 661Returns the number of coro that are currently in the ready state,
528i.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
529indirectly. 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
530currently 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>
531would 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
532coroutines. 666coro.
533 667
534=item my $guard = Coro::guard { ... } 668=item my $guard = Coro::guard { ... }
535 669
536This creates and returns a guard object. Nothing happens until the object 670This function still exists, but is deprecated. Please use the
537gets destroyed, in which case the codeblock given as argument will be 671C<Guard::guard> function instead.
538executed. This is useful to free locks or other resources in case of a
539runtime error or when the coroutine gets canceled, as in both cases the
540guard block will be executed. The guard object supports only one method,
541C<< ->cancel >>, which will keep the codeblock from being executed.
542 672
543Example: set some flag and clear it again when the coroutine gets canceled
544or the function returns:
545
546 sub do_something {
547 my $guard = Coro::guard { $busy = 0 };
548 $busy = 1;
549
550 # do something that requires $busy to be true
551 }
552
553=cut 673=cut
554 674
555sub guard(&) { 675BEGIN { *guard = \&Guard::guard }
556 bless \(my $cb = $_[0]), "Coro::guard"
557}
558
559sub Coro::guard::cancel {
560 ${$_[0]} = sub { };
561}
562
563sub Coro::guard::DESTROY {
564 ${$_[0]}->();
565}
566
567 676
568=item unblock_sub { ... } 677=item unblock_sub { ... }
569 678
570This utility function takes a BLOCK or code reference and "unblocks" it, 679This utility function takes a BLOCK or code reference and "unblocks" it,
571returning a new coderef. Unblocking means that calling the new coderef 680returning a new coderef. Unblocking means that calling the new coderef
572will return immediately without blocking, returning nothing, while the 681will return immediately without blocking, returning nothing, while the
573original code ref will be called (with parameters) from within another 682original code ref will be called (with parameters) from within another
574coroutine. 683coro.
575 684
576The 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
577venerable L<Event|Event> module) are not coroutine-safe (a weaker form 686venerable L<Event|Event> module) are not thread-safe (a weaker form
578of thread-safety). This means you must not block within event callbacks, 687of reentrancy). This means you must not block within event callbacks,
579otherwise you might suffer from crashes or worse. The only event library 688otherwise you might suffer from crashes or worse. The only event library
580currently 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>.
581 690
582This function allows your callbacks to block by executing them in another 691This function allows your callbacks to block by executing them in another
583coroutine 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
584is 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
585disk, for example. 694disk, for example.
586 695
587In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when 696In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
588creating event callbacks that want to block. 697creating event callbacks that want to block.
589 698
590If 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
591another coroutine, or puts some other coroutine into the ready queue), 700another coro, or puts some other coro into the ready queue), there is
592there is no reason to use C<unblock_sub>. 701no reason to use C<unblock_sub>.
593 702
594Note 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
595are 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
596use 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
597provides callbacks that are the result of some event callback, then you 706provides callbacks that are the result of some event callback, then you
… …
629 } 738 }
630} 739}
631 740
632=item $cb = Coro::rouse_cb 741=item $cb = Coro::rouse_cb
633 742
634Create and return a "rouse callback". That's a code reference that, when 743Create and return a "rouse callback". That's a code reference that,
635called, will save its arguments and notify the owner coroutine of the 744when called, will remember a copy of its arguments and notify the owner
636callback. 745coro of the callback.
637 746
638See the next function. 747See the next function.
639 748
640=item @args = Coro::rouse_wait [$cb] 749=item @args = Coro::rouse_wait [$cb]
641 750
642Wait for the specified rouse callback (or the last one tht was created in 751Wait for the specified rouse callback (or the last one that was created in
643this coroutine). 752this coro).
644 753
645As soon as the callback is invoked (or when the calback was invoked before 754As soon as the callback is invoked (or when the callback was invoked
646C<rouse_wait>), it will return a copy of the arguments originally passed 755before C<rouse_wait>), it will return the arguments originally passed to
647to the rouse callback. 756the rouse callback. In scalar context, that means you get the I<last>
757argument, just as if C<rouse_wait> had a C<return ($a1, $a2, $a3...)>
758statement at the end.
648 759
649See 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.
650 761
651=back 762=back
652 763
… …
654 765
6551; 7661;
656 767
657=head1 HOW TO WAIT FOR A CALLBACK 768=head1 HOW TO WAIT FOR A CALLBACK
658 769
659It 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
660called. This occurs naturally when you use coroutines in an otherwise 771called. This occurs naturally when you use coro in an otherwise
661event-based program, or when you use event-based libraries. 772event-based program, or when you use event-based libraries.
662 773
663These typically register a callback for some event, and call that callback 774These typically register a callback for some event, and call that callback
664when the event occured. In a coroutine, however, you typically want to 775when the event occured. In a coro, however, you typically want to
665just wait for the event, simplyifying things. 776just wait for the event, simplyifying things.
666 777
667For example C<< AnyEvent->child >> registers a callback to be called when 778For example C<< AnyEvent->child >> registers a callback to be called when
668a specific child has exited: 779a specific child has exited:
669 780
670 my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... }); 781 my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... });
671 782
672But from withina coroutine, you often just want to write this: 783But from within a coro, you often just want to write this:
673 784
674 my $status = wait_for_child $pid; 785 my $status = wait_for_child $pid;
675 786
676Coro offers two functions specifically designed to make this easy, 787Coro offers two functions specifically designed to make this easy,
677C<Coro::rouse_cb> and C<Coro::rouse_wait>. 788C<Coro::rouse_cb> and C<Coro::rouse_wait>.
678 789
679The first function, C<rouse_cb>, generates and returns a callback that, 790The first function, C<rouse_cb>, generates and returns a callback that,
680when invoked, will save it's arguments and notify the coroutine that 791when invoked, will save its arguments and notify the coro that
681created the callback. 792created the callback.
682 793
683The second function, C<rouse_wait>, waits for the callback to be called 794The second function, C<rouse_wait>, waits for the callback to be called
684(by calling C<schedule> to go to sleep) and returns the arguments 795(by calling C<schedule> to go to sleep) and returns the arguments
685originally passed to the callback. 796originally passed to the callback.
… …
700you can roll your own, using C<schedule>: 811you can roll your own, using C<schedule>:
701 812
702 sub wait_for_child($) { 813 sub wait_for_child($) {
703 my ($pid) = @_; 814 my ($pid) = @_;
704 815
705 # store the current coroutine in $current, 816 # store the current coro in $current,
706 # and provide result variables for the closure passed to ->child 817 # and provide result variables for the closure passed to ->child
707 my $current = $Coro::current; 818 my $current = $Coro::current;
708 my ($done, $rstatus); 819 my ($done, $rstatus);
709 820
710 # pass a closure to ->child 821 # pass a closure to ->child
… …
726 837
727=item fork with pthread backend 838=item fork with pthread backend
728 839
729When Coro is compiled using the pthread backend (which isn't recommended 840When Coro is compiled using the pthread backend (which isn't recommended
730but required on many BSDs as their libcs are completely broken), then 841but required on many BSDs as their libcs are completely broken), then
731coroutines 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
732fix your libc and use a saner backend. 843fix your libc and use a saner backend.
733 844
734=item perl process emulation ("threads") 845=item perl process emulation ("threads")
735 846
736This 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
737module from the same thread (this requirement might be removed in the 848module from the first thread (this requirement might be removed in the
738future 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
739this). I recommend disabling thread support and using processes, as having 850this). I recommend disabling thread support and using processes, as having
740the windows process emulation enabled under unix roughly halves perl 851the windows process emulation enabled under unix roughly halves perl
741performance, even when not used. 852performance, even when not used.
742 853
743=item coroutine switching not signal safe 854=item coro switching is not signal safe
744 855
745You must not switch to another coroutine from within a signal handler 856You must not switch to another coro from within a signal handler
746(only relevant with %SIG - most event libraries provide safe signals). 857(only relevant with %SIG - most event libraries provide safe signals).
747 858
748That 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
749current coroutine - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or 860current coro - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or
750anything that calls those. Everything else, including calling C<ready>, 861anything that calls those. Everything else, including calling C<ready>,
751works. 862works.
752 863
753=back 864=back
754 865
… …
759 870
760Debugging: L<Coro::Debug>. 871Debugging: L<Coro::Debug>.
761 872
762Support/Utility: L<Coro::Specific>, L<Coro::Util>. 873Support/Utility: L<Coro::Specific>, L<Coro::Util>.
763 874
764Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, 875Locking and IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>,
765L<Coro::SemaphoreSet>, L<Coro::RWLock>. 876L<Coro::SemaphoreSet>, L<Coro::RWLock>.
766 877
767IO/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>.
768 879
769Compatibility: L<Coro::LWP> (but see also L<AnyEvent::HTTP> for 880Compatibility with other modules: L<Coro::LWP> (but see also L<AnyEvent::HTTP> for
770a better-working alternative), L<Coro::BDB>, L<Coro::Storable>, 881a better-working alternative), L<Coro::BDB>, L<Coro::Storable>,
771L<Coro::Select>. 882L<Coro::Select>.
772 883
773XS API: L<Coro::MakeMaker>. 884XS API: L<Coro::MakeMaker>.
774 885
775Low level Configuration, Coroutine Environment: L<Coro::State>. 886Low level Configuration, Thread Environment, Continuations: L<Coro::State>.
776 887
777=head1 AUTHOR 888=head1 AUTHOR
778 889
779 Marc Lehmann <schmorp@schmorp.de> 890 Marc Lehmann <schmorp@schmorp.de>
780 http://home.schmorp.de/ 891 http://home.schmorp.de/

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