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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 = 5.17;
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
197=cut
198
199sub async(&@) {
200 my $coro = new Coro @_;
201 $coro->ready;
202 $coro
203}
204
205=item async_pool { ... } [@args...] 212=item async_pool { ... } [@args...]
206 213
207Similar to C<async>, but uses a coroutine pool, so you should not call 214Similar 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 215terminate 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 216coro that might have executed other code already (which can be good
210or bad :). 217or bad :).
211 218
212On the plus side, this function is about twice as fast as creating (and 219On 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 220destroying) a completely new coro, so if you need a lot of generic
214coroutines in quick successsion, use C<async_pool>, not C<async>. 221coros in quick successsion, use C<async_pool>, not C<async>.
215 222
216The code block is executed in an C<eval> context and a warning will be 223The 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 224issued 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> 225C<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, 226will not work in the expected way, unless you call terminate or cancel,
220which somehow defeats the purpose of pooling (but is fine in the 227which somehow defeats the purpose of pooling (but is fine in the
221exceptional case). 228exceptional case).
222 229
223The priority will be reset to C<0> after each run, tracing will be 230The priority will be reset to C<0> after each run, tracing will be
224disabled, the description will be reset and the default output filehandle 231disabled, the description will be reset and the default output filehandle
225gets restored, so you can change all these. Otherwise the coroutine will 232gets 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 233be 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 234stuff such as C<$/> you I<must needs> revert that change, which is most
228simply done by using local as in: C<< local $/ >>. 235simply done by using local as in: C<< local $/ >>.
229 236
230The idle pool size is limited to C<8> idle coroutines (this can be 237The 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 238adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle
232coros as required. 239coros as required.
233 240
234If you are concerned about pooled coroutines growing a lot because a 241If 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 242single 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 243{ 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 244addition to that, when the stacks used by a handler grows larger than 32kb
238(adjustable via $Coro::POOL_RSS) it will also be destroyed. 245(adjustable via $Coro::POOL_RSS) it will also be destroyed.
239 246
… …
256=back 263=back
257 264
258=head1 STATIC METHODS 265=head1 STATIC METHODS
259 266
260Static methods are actually functions that implicitly operate on the 267Static methods are actually functions that implicitly operate on the
261current coroutine. 268current coro.
262 269
263=over 4 270=over 4
264 271
265=item schedule 272=item schedule
266 273
267Calls the scheduler. The scheduler will find the next coroutine that is 274Calls the scheduler. The scheduler will find the next coro that is
268to be run from the ready queue and switches to it. The next coroutine 275to be run from the ready queue and switches to it. The next coro
269to be run is simply the one with the highest priority that is longest 276to be run is simply the one with the highest priority that is longest
270in its ready queue. If there is no coroutine ready, it will clal the 277in its ready queue. If there is no coro ready, it will clal the
271C<$Coro::idle> hook. 278C<$Coro::idle> hook.
272 279
273Please note that the current coroutine will I<not> be put into the ready 280Please 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 281queue, so calling this function usually means you will never be called
275again unless something else (e.g. an event handler) calls C<< ->ready >>, 282again unless something else (e.g. an event handler) calls C<< ->ready >>,
276thus waking you up. 283thus waking you up.
277 284
278This makes C<schedule> I<the> generic method to use to block the current 285This 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 286coro and wait for events: first you remember the current coro in
280a variable, then arrange for some callback of yours to call C<< ->ready 287a 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 288>> 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, 289yourself 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 290so you need to check whether the event indeed happened, e.g. by storing the
284status in a variable. 291status in a variable.
285 292
286See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks. 293See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks.
287 294
288=item cede 295=item cede
289 296
290"Cede" to other coroutines. This function puts the current coroutine into 297"Cede" to other coros. This function puts the current coro into
291the ready queue and calls C<schedule>, which has the effect of giving 298the ready queue and calls C<schedule>, which has the effect of giving
292up the current "timeslice" to other coroutines of the same or higher 299up the current "timeslice" to other coros of the same or higher
293priority. Once your coroutine gets its turn again it will automatically be 300priority. Once your coro gets its turn again it will automatically be
294resumed. 301resumed.
295 302
296This function is often called C<yield> in other languages. 303This function is often called C<yield> in other languages.
297 304
298=item Coro::cede_notself 305=item Coro::cede_notself
299 306
300Works like cede, but is not exported by default and will cede to I<any> 307Works like cede, but is not exported by default and will cede to I<any>
301coroutine, regardless of priority. This is useful sometimes to ensure 308coro, regardless of priority. This is useful sometimes to ensure
302progress is made. 309progress is made.
303 310
304=item terminate [arg...] 311=item terminate [arg...]
305 312
306Terminates the current coroutine with the given status values (see L<cancel>). 313Terminates the current coro with the given status values (see L<cancel>).
314
315=item Coro::on_enter BLOCK, Coro::on_leave BLOCK
316
317These function install enter and leave winders in the current scope. The
318enter block will be executed when on_enter is called and whenever the
319current coro is re-entered by the scheduler, while the leave block is
320executed whenever the current coro is blocked by the scheduler, and
321also when the containing scope is exited (by whatever means, be it exit,
322die, last etc.).
323
324I<Neither invoking the scheduler, nor exceptions, are allowed within those
325BLOCKs>. That means: do not even think about calling C<die> without an
326eval, and do not even think of entering the scheduler in any way.
327
328Since both BLOCKs are tied to the current scope, they will automatically
329be removed when the current scope exits.
330
331These functions implement the same concept as C<dynamic-wind> in scheme
332does, and are useful when you want to localise some resource to a specific
333coro.
334
335They slow down thread switching considerably for coros that use them
336(about 40% for a BLOCK with a single assignment, so thread switching is
337still reasonably fast if the handlers are fast).
338
339These functions are best understood by an example: The following function
340will change the current timezone to "Antarctica/South_Pole", which
341requires a call to C<tzset>, but by using C<on_enter> and C<on_leave>,
342which remember/change the current timezone and restore the previous
343value, respectively, the timezone is only changed for the coro that
344installed those handlers.
345
346 use POSIX qw(tzset);
347
348 async {
349 my $old_tz; # store outside TZ value here
350
351 Coro::on_enter {
352 $old_tz = $ENV{TZ}; # remember the old value
353
354 $ENV{TZ} = "Antarctica/South_Pole";
355 tzset; # enable new value
356 };
357
358 Coro::on_leave {
359 $ENV{TZ} = $old_tz;
360 tzset; # restore old value
361 };
362
363 # at this place, the timezone is Antarctica/South_Pole,
364 # without disturbing the TZ of any other coro.
365 };
366
367This can be used to localise about any resource (locale, uid, current
368working directory etc.) to a block, despite the existance of other
369coros.
370
371Another interesting example implements time-sliced multitasking using
372interval timers (this could obviously be optimised, but does the job):
373
374 # "timeslice" the given block
375 sub timeslice(&) {
376 use Time::HiRes ();
377
378 Coro::on_enter {
379 # on entering the thread, we set an VTALRM handler to cede
380 $SIG{VTALRM} = sub { cede };
381 # and then start the interval timer
382 Time::HiRes::setitimer &Time::HiRes::ITIMER_VIRTUAL, 0.01, 0.01;
383 };
384 Coro::on_leave {
385 # on leaving the thread, we stop the interval timer again
386 Time::HiRes::setitimer &Time::HiRes::ITIMER_VIRTUAL, 0, 0;
387 };
388
389 &{+shift};
390 }
391
392 # use like this:
393 timeslice {
394 # The following is an endless loop that would normally
395 # monopolise the process. Since it runs in a timesliced
396 # environment, it will regularly cede to other threads.
397 while () { }
398 };
399
307 400
308=item killall 401=item killall
309 402
310Kills/terminates/cancels all coroutines except the currently running 403Kills/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.
313 404
314Note that while this will try to free some of the main programs resources, 405Note that while this will try to free some of the main interpreter
406resources 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 407cannot 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. 408calls this function, there will be some one-time resource leak.
317 409
318=cut 410=cut
319 411
320sub killall { 412sub killall {
321 for (Coro::State::list) { 413 for (Coro::State::list) {
… …
324 } 416 }
325} 417}
326 418
327=back 419=back
328 420
329=head1 COROUTINE OBJECT METHODS 421=head1 CORO OBJECT METHODS
330 422
331These are the methods you can call on coroutine objects (or to create 423These are the methods you can call on coro objects (or to create
332them). 424them).
333 425
334=over 4 426=over 4
335 427
336=item new Coro \&sub [, @args...] 428=item new Coro \&sub [, @args...]
337 429
338Create a new coroutine and return it. When the sub returns, the coroutine 430Create a new coro and return it. When the sub returns, the coro
339automatically terminates as if C<terminate> with the returned values were 431automatically terminates as if C<terminate> with the returned values were
340called. To make the coroutine run you must first put it into the ready 432called. To make the coro run you must first put it into the ready
341queue by calling the ready method. 433queue by calling the ready method.
342 434
343See C<async> and C<Coro::State::new> for additional info about the 435See C<async> and C<Coro::State::new> for additional info about the
344coroutine environment. 436coro environment.
345 437
346=cut 438=cut
347 439
348sub _terminate { 440sub _coro_run {
349 terminate &{+shift}; 441 terminate &{+shift};
350} 442}
351 443
352=item $success = $coroutine->ready 444=item $success = $coro->ready
353 445
354Put the given coroutine into the end of its ready queue (there is one 446Put 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 447queue for each priority) and return true. If the coro is already in
356the ready queue, do nothing and return false. 448the ready queue, do nothing and return false.
357 449
358This ensures that the scheduler will resume this coroutine automatically 450This ensures that the scheduler will resume this coro automatically
359once all the coroutines of higher priority and all coroutines of the same 451once all the coro of higher priority and all coro of the same
360priority that were put into the ready queue earlier have been resumed. 452priority that were put into the ready queue earlier have been resumed.
361 453
454=item $coro->suspend
455
456Suspends the specified coro. A suspended coro works just like any other
457coro, except that the scheduler will not select a suspended coro for
458execution.
459
460Suspending a coro can be useful when you want to keep the coro from
461running, but you don't want to destroy it, or when you want to temporarily
462freeze a coro (e.g. for debugging) to resume it later.
463
464A scenario for the former would be to suspend all (other) coros after a
465fork and keep them alive, so their destructors aren't called, but new
466coros can be created.
467
468=item $coro->resume
469
470If the specified coro was suspended, it will be resumed. Note that when
471the coro was in the ready queue when it was suspended, it might have been
472unreadied by the scheduler, so an activation might have been lost.
473
474To avoid this, it is best to put a suspended coro into the ready queue
475unconditionally, as every synchronisation mechanism must protect itself
476against spurious wakeups, and the one in the Coro family certainly do
477that.
478
362=item $is_ready = $coroutine->is_ready 479=item $is_ready = $coro->is_ready
363 480
364Return whether the coroutine is currently the ready queue or not, 481Returns true iff the Coro object is in the ready queue. Unless the Coro
482object gets destroyed, it will eventually be scheduled by the scheduler.
365 483
484=item $is_running = $coro->is_running
485
486Returns true iff the Coro object is currently running. Only one Coro object
487can ever be in the running state (but it currently is possible to have
488multiple running Coro::States).
489
490=item $is_suspended = $coro->is_suspended
491
492Returns true iff this Coro object has been suspended. Suspended Coros will
493not ever be scheduled.
494
366=item $coroutine->cancel (arg...) 495=item $coro->cancel (arg...)
367 496
368Terminates the given coroutine and makes it return the given arguments as 497Terminates the given Coro and makes it return the given arguments as
369status (default: the empty list). Never returns if the coroutine is the 498status (default: the empty list). Never returns if the Coro is the
370current coroutine. 499current Coro.
371 500
372=cut 501=cut
373 502
374sub cancel { 503sub cancel {
375 my $self = shift; 504 my $self = shift;
376 505
377 if ($current == $self) { 506 if ($current == $self) {
378 terminate @_; 507 terminate @_;
379 } else { 508 } else {
380 $self->{_status} = [@_]; 509 $self->{_status} = [@_];
381 $self->_cancel; 510 Coro::State::cancel $self;
382 } 511 }
383} 512}
384 513
385=item $coroutine->schedule_to 514=item $coro->schedule_to
386 515
387Puts the current coroutine to sleep (like C<Coro::schedule>), but instead 516Puts the current coro to sleep (like C<Coro::schedule>), but instead
388of continuing with the next coro from the ready queue, always switch to 517of continuing with the next coro from the ready queue, always switch to
389the given coroutine object (regardless of priority etc.). The readyness 518the given coro object (regardless of priority etc.). The readyness
390state of that coroutine isn't changed. 519state of that coro isn't changed.
391 520
392This is an advanced method for special cases - I'd love to hear about any 521This is an advanced method for special cases - I'd love to hear about any
393uses for this one. 522uses for this one.
394 523
395=item $coroutine->cede_to 524=item $coro->cede_to
396 525
397Like C<schedule_to>, but puts the current coroutine into the ready 526Like C<schedule_to>, but puts the current coro into the ready
398queue. This has the effect of temporarily switching to the given 527queue. This has the effect of temporarily switching to the given
399coroutine, and continuing some time later. 528coro, and continuing some time later.
400 529
401This is an advanced method for special cases - I'd love to hear about any 530This is an advanced method for special cases - I'd love to hear about any
402uses for this one. 531uses for this one.
403 532
404=item $coroutine->throw ([$scalar]) 533=item $coro->throw ([$scalar])
405 534
406If C<$throw> is specified and defined, it will be thrown as an exception 535If C<$throw> is specified and defined, it will be thrown as an exception
407inside the coroutine at the next convenient point in time. Otherwise 536inside the coro at the next convenient point in time. Otherwise
408clears the exception object. 537clears the exception object.
409 538
410Coro will check for the exception each time a schedule-like-function 539Coro will check for the exception each time a schedule-like-function
411returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down 540returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down
412>>, C<< Coro::Handle->readable >> and so on. Most of these functions 541>>, C<< Coro::Handle->readable >> and so on. Most of these functions
… …
414 543
415The exception object will be thrown "as is" with the specified scalar in 544The exception object will be thrown "as is" with the specified scalar in
416C<$@>, i.e. if it is a string, no line number or newline will be appended 545C<$@>, i.e. if it is a string, no line number or newline will be appended
417(unlike with C<die>). 546(unlike with C<die>).
418 547
419This can be used as a softer means than C<cancel> to ask a coroutine to 548This 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 549end 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 550termination, and if the exception isn't caught it might well end the whole
422program. 551program.
423 552
424You might also think of C<throw> as being the moral equivalent of 553You 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). 554C<kill>ing a coro with a signal (in this case, a scalar).
426 555
427=item $coroutine->join 556=item $coro->join
428 557
429Wait until the coroutine terminates and return any values given to the 558Wait until the coro terminates and return any values given to the
430C<terminate> or C<cancel> functions. C<join> can be called concurrently 559C<terminate> or C<cancel> functions. C<join> can be called concurrently
431from multiple coroutines, and all will be resumed and given the status 560from multiple coro, and all will be resumed and given the status
432return once the C<$coroutine> terminates. 561return once the C<$coro> terminates.
433 562
434=cut 563=cut
435 564
436sub join { 565sub join {
437 my $self = shift; 566 my $self = shift;
… …
448 } 577 }
449 578
450 wantarray ? @{$self->{_status}} : $self->{_status}[0]; 579 wantarray ? @{$self->{_status}} : $self->{_status}[0];
451} 580}
452 581
453=item $coroutine->on_destroy (\&cb) 582=item $coro->on_destroy (\&cb)
454 583
455Registers a callback that is called when this coroutine gets destroyed, 584Registers a callback that is called when this coro gets destroyed,
456but before it is joined. The callback gets passed the terminate arguments, 585but before it is joined. The callback gets passed the terminate arguments,
457if any, and I<must not> die, under any circumstances. 586if any, and I<must not> die, under any circumstances.
458 587
459=cut 588=cut
460 589
… …
462 my ($self, $cb) = @_; 591 my ($self, $cb) = @_;
463 592
464 push @{ $self->{_on_destroy} }, $cb; 593 push @{ $self->{_on_destroy} }, $cb;
465} 594}
466 595
467=item $oldprio = $coroutine->prio ($newprio) 596=item $oldprio = $coro->prio ($newprio)
468 597
469Sets (or gets, if the argument is missing) the priority of the 598Sets (or gets, if the argument is missing) the priority of the
470coroutine. Higher priority coroutines get run before lower priority 599coro. Higher priority coro get run before lower priority
471coroutines. Priorities are small signed integers (currently -4 .. +3), 600coro. Priorities are small signed integers (currently -4 .. +3),
472that you can refer to using PRIO_xxx constants (use the import tag :prio 601that you can refer to using PRIO_xxx constants (use the import tag :prio
473to get then): 602to get then):
474 603
475 PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN 604 PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
476 3 > 1 > 0 > -1 > -3 > -4 605 3 > 1 > 0 > -1 > -3 > -4
477 606
478 # set priority to HIGH 607 # set priority to HIGH
479 current->prio(PRIO_HIGH); 608 current->prio (PRIO_HIGH);
480 609
481The idle coroutine ($Coro::idle) always has a lower priority than any 610The idle coro ($Coro::idle) always has a lower priority than any
482existing coroutine. 611existing coro.
483 612
484Changing the priority of the current coroutine will take effect immediately, 613Changing the priority of the current coro will take effect immediately,
485but changing the priority of coroutines in the ready queue (but not 614but changing the priority of coro in the ready queue (but not
486running) will only take effect after the next schedule (of that 615running) will only take effect after the next schedule (of that
487coroutine). This is a bug that will be fixed in some future version. 616coro). This is a bug that will be fixed in some future version.
488 617
489=item $newprio = $coroutine->nice ($change) 618=item $newprio = $coro->nice ($change)
490 619
491Similar to C<prio>, but subtract the given value from the priority (i.e. 620Similar to C<prio>, but subtract the given value from the priority (i.e.
492higher values mean lower priority, just as in unix). 621higher values mean lower priority, just as in unix).
493 622
494=item $olddesc = $coroutine->desc ($newdesc) 623=item $olddesc = $coro->desc ($newdesc)
495 624
496Sets (or gets in case the argument is missing) the description for this 625Sets (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 626coro. This is just a free-form string you can associate with a
498coroutine. 627coro.
499 628
500This method simply sets the C<< $coroutine->{desc} >> member to the given 629This method simply sets the C<< $coro->{desc} >> member to the given
501string. You can modify this member directly if you wish. 630string. You can modify this member directly if you wish.
502 631
503=cut 632=cut
504 633
505sub desc { 634sub desc {
… …
519 648
520=over 4 649=over 4
521 650
522=item Coro::nready 651=item Coro::nready
523 652
524Returns the number of coroutines that are currently in the ready state, 653Returns the number of coro that are currently in the ready state,
525i.e. that can be switched to by calling C<schedule> directory or 654i.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 655indirectly. 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> 656currently 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 657would cause a deadlock unless there is an idle handler that wakes up some
529coroutines. 658coro.
530 659
531=item my $guard = Coro::guard { ... } 660=item my $guard = Coro::guard { ... }
532 661
533This creates and returns a guard object. Nothing happens until the object 662This function still exists, but is deprecated. Please use the
534gets destroyed, in which case the codeblock given as argument will be 663C<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.
539 664
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 665=cut
551 666
552sub guard(&) { 667BEGIN { *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
564 668
565=item unblock_sub { ... } 669=item unblock_sub { ... }
566 670
567This utility function takes a BLOCK or code reference and "unblocks" it, 671This utility function takes a BLOCK or code reference and "unblocks" it,
568returning a new coderef. Unblocking means that calling the new coderef 672returning a new coderef. Unblocking means that calling the new coderef
569will return immediately without blocking, returning nothing, while the 673will return immediately without blocking, returning nothing, while the
570original code ref will be called (with parameters) from within another 674original code ref will be called (with parameters) from within another
571coroutine. 675coro.
572 676
573The reason this function exists is that many event libraries (such as the 677The reason this function exists is that many event libraries (such as the
574venerable L<Event|Event> module) are not coroutine-safe (a weaker form 678venerable L<Event|Event> module) are not thread-safe (a weaker form
575of thread-safety). This means you must not block within event callbacks, 679of reentrancy). This means you must not block within event callbacks,
576otherwise you might suffer from crashes or worse. The only event library 680otherwise 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>. 681currently known that is safe to use without C<unblock_sub> is L<EV>.
578 682
579This function allows your callbacks to block by executing them in another 683This function allows your callbacks to block by executing them in another
580coroutine where it is safe to block. One example where blocking is handy 684coro 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 685is when you use the L<Coro::AIO|Coro::AIO> functions to save results to
582disk, for example. 686disk, for example.
583 687
584In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when 688In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
585creating event callbacks that want to block. 689creating event callbacks that want to block.
586 690
587If your handler does not plan to block (e.g. simply sends a message to 691If 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), 692another coro, or puts some other coro into the ready queue), there is
589there is no reason to use C<unblock_sub>. 693no reason to use C<unblock_sub>.
590 694
591Note that you also need to use C<unblock_sub> for any other callbacks that 695Note 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 696are 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 697use 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 698provides callbacks that are the result of some event callback, then you
… …
626 } 730 }
627} 731}
628 732
629=item $cb = Coro::rouse_cb 733=item $cb = Coro::rouse_cb
630 734
631Create and return a "rouse callback". That's a code reference that, when 735Create and return a "rouse callback". That's a code reference that,
632called, will save its arguments and notify the owner coroutine of the 736when called, will remember a copy of its arguments and notify the owner
633callback. 737coro of the callback.
634 738
635See the next function. 739See the next function.
636 740
637=item @args = Coro::rouse_wait [$cb] 741=item @args = Coro::rouse_wait [$cb]
638 742
639Wait for the specified rouse callback (or the last one tht was created in 743Wait for the specified rouse callback (or the last one that was created in
640this coroutine). 744this coro).
641 745
642As soon as the callback is invoked (or when the calback was invoked before 746As soon as the callback is invoked (or when the callback was invoked
643C<rouse_wait>), it will return a copy of the arguments originally passed 747before C<rouse_wait>), it will return the arguments originally passed to
644to the rouse callback. 748the rouse callback. In scalar context, that means you get the I<last>
749argument, just as if C<rouse_wait> had a C<return ($a1, $a2, $a3...)>
750statement at the end.
645 751
646See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example. 752See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example.
647 753
648=back 754=back
649 755
… …
651 757
6521; 7581;
653 759
654=head1 HOW TO WAIT FOR A CALLBACK 760=head1 HOW TO WAIT FOR A CALLBACK
655 761
656It is very common for a coroutine to wait for some callback to be 762It is very common for a coro to wait for some callback to be
657called. This occurs naturally when you use coroutines in an otherwise 763called. This occurs naturally when you use coro in an otherwise
658event-based program, or when you use event-based libraries. 764event-based program, or when you use event-based libraries.
659 765
660These typically register a callback for some event, and call that callback 766These typically register a callback for some event, and call that callback
661when the event occured. In a coroutine, however, you typically want to 767when the event occured. In a coro, however, you typically want to
662just wait for the event, simplyifying things. 768just wait for the event, simplyifying things.
663 769
664For example C<< AnyEvent->child >> registers a callback to be called when 770For example C<< AnyEvent->child >> registers a callback to be called when
665a specific child has exited: 771a specific child has exited:
666 772
667 my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... }); 773 my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... });
668 774
669But from withina coroutine, you often just want to write this: 775But from within a coro, you often just want to write this:
670 776
671 my $status = wait_for_child $pid; 777 my $status = wait_for_child $pid;
672 778
673Coro offers two functions specifically designed to make this easy, 779Coro offers two functions specifically designed to make this easy,
674C<Coro::rouse_cb> and C<Coro::rouse_wait>. 780C<Coro::rouse_cb> and C<Coro::rouse_wait>.
675 781
676The first function, C<rouse_cb>, generates and returns a callback that, 782The first function, C<rouse_cb>, generates and returns a callback that,
677when invoked, will save it's arguments and notify the coroutine that 783when invoked, will save its arguments and notify the coro that
678created the callback. 784created the callback.
679 785
680The second function, C<rouse_wait>, waits for the callback to be called 786The second function, C<rouse_wait>, waits for the callback to be called
681(by calling C<schedule> to go to sleep) and returns the arguments 787(by calling C<schedule> to go to sleep) and returns the arguments
682originally passed to the callback. 788originally passed to the callback.
… …
697you can roll your own, using C<schedule>: 803you can roll your own, using C<schedule>:
698 804
699 sub wait_for_child($) { 805 sub wait_for_child($) {
700 my ($pid) = @_; 806 my ($pid) = @_;
701 807
702 # store the current coroutine in $current, 808 # store the current coro in $current,
703 # and provide result variables for the closure passed to ->child 809 # and provide result variables for the closure passed to ->child
704 my $current = $Coro::current; 810 my $current = $Coro::current;
705 my ($done, $rstatus); 811 my ($done, $rstatus);
706 812
707 # pass a closure to ->child 813 # pass a closure to ->child
… …
723 829
724=item fork with pthread backend 830=item fork with pthread backend
725 831
726When Coro is compiled using the pthread backend (which isn't recommended 832When Coro is compiled using the pthread backend (which isn't recommended
727but required on many BSDs as their libcs are completely broken), then 833but required on many BSDs as their libcs are completely broken), then
728coroutines will not survive a fork. There is no known workaround except to 834coro will not survive a fork. There is no known workaround except to
729fix your libc and use a saner backend. 835fix your libc and use a saner backend.
730 836
731=item perl process emulation ("threads") 837=item perl process emulation ("threads")
732 838
733This module is not perl-pseudo-thread-safe. You should only ever use this 839This 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 840module from the first thread (this requirement might be removed in the
735future to allow per-thread schedulers, but Coro::State does not yet allow 841future to allow per-thread schedulers, but Coro::State does not yet allow
736this). I recommend disabling thread support and using processes, as having 842this). I recommend disabling thread support and using processes, as having
737the windows process emulation enabled under unix roughly halves perl 843the windows process emulation enabled under unix roughly halves perl
738performance, even when not used. 844performance, even when not used.
739 845
740=item coroutine switching not signal safe 846=item coro switching is not signal safe
741 847
742You must not switch to another coroutine from within a signal handler 848You must not switch to another coro from within a signal handler
743(only relevant with %SIG - most event libraries provide safe signals). 849(only relevant with %SIG - most event libraries provide safe signals).
744 850
745That means you I<MUST NOT> call any function that might "block" the 851That means you I<MUST NOT> call any function that might "block" the
746current coroutine - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or 852current coro - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or
747anything that calls those. Everything else, including calling C<ready>, 853anything that calls those. Everything else, including calling C<ready>,
748works. 854works.
749 855
750=back 856=back
751 857
… …
756 862
757Debugging: L<Coro::Debug>. 863Debugging: L<Coro::Debug>.
758 864
759Support/Utility: L<Coro::Specific>, L<Coro::Util>. 865Support/Utility: L<Coro::Specific>, L<Coro::Util>.
760 866
761Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>. 867Locking and IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>,
868L<Coro::SemaphoreSet>, L<Coro::RWLock>.
762 869
763IO/Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>. 870I/O and Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>.
764 871
765Compatibility: L<Coro::LWP>, L<Coro::BDB>, L<Coro::Storable>, L<Coro::Select>. 872Compatibility with other modules: L<Coro::LWP> (but see also L<AnyEvent::HTTP> for
873a better-working alternative), L<Coro::BDB>, L<Coro::Storable>,
874L<Coro::Select>.
766 875
767XS API: L<Coro::MakeMaker>. 876XS API: L<Coro::MakeMaker>.
768 877
769Low level Configuration, Coroutine Environment: L<Coro::State>. 878Low level Configuration, Thread Environment, Continuations: L<Coro::State>.
770 879
771=head1 AUTHOR 880=head1 AUTHOR
772 881
773 Marc Lehmann <schmorp@schmorp.de> 882 Marc Lehmann <schmorp@schmorp.de>
774 http://home.schmorp.de/ 883 http://home.schmorp.de/

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