ViewVC Help
View File | Revision Log | Show Annotations | Download File
/cvs/Coro/Coro.pm
(Generate patch)

Comparing Coro/Coro.pm (file contents):
Revision 1.233 by root, Fri Nov 21 06:02:07 2008 UTC vs.
Revision 1.254 by root, Tue Jun 16 17:19:08 2009 UTC

1=head1 NAME 1=head1 NAME
2 2
3Coro - coroutine process abstraction 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. Coroutines are similar to 31For a tutorial-style introduction, please read the L<Coro::Intro>
32threads but don't (in general) run in parallel at the same time even 32manpage. This manpage mainly contains reference information.
33on SMP machines. The specific flavor of coroutine used in this module
34also guarantees you that it will not switch between coroutines unless
35necessary, at easily-identified points in your program, so locking and
36parallel access are rarely an issue, making coroutine programming much
37safer and easier than threads programming.
38 33
39Unlike a normal perl program, however, coroutines allow you to have 34This module collection manages continuations in general, most often in
40multiple running interpreters that share data, which is especially useful 35the form of cooperative threads (also called coros, or simply "coro"
41to code pseudo-parallel processes and for event-based programming, such as 36in the documentation). They are similar to kernel threads but don't (in
42multiple HTTP-GET requests running concurrently. See L<Coro::AnyEvent> to 37general) run in parallel at the same time even on SMP machines. The
43learn more. 38specific flavor of thread offered by this module also guarantees you that
39it will not switch between threads unless necessary, at easily-identified
40points in your program, so locking and parallel access are rarely an
41issue, making thread programming much safer and easier than using other
42thread models.
44 43
45Coroutines are also useful because Perl has no support for threads (the so 44Unlike the so-called "Perl threads" (which are not actually real threads
46called "threads" that perl offers are nothing more than the (bad) process 45but only the windows process emulation ported to unix, and as such act
47emulation coming from the Windows platform: On standard operating systems 46as processes), Coro provides a full shared address space, which makes
48they serve no purpose whatsoever, except by making your programs slow and 47communication between threads very easy. And Coro's threads are fast,
49making them use a lot of memory. Best disable them when building perl, or 48too: disabling the Windows process emulation code in your perl and using
50aks your software vendor/distributor to do it for you). 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.
51 53
54Coro achieves that by supporting multiple running interpreters that share
55data, which is especially useful to code pseudo-parallel processes and
56for event-based programming, such as multiple HTTP-GET requests running
57concurrently. See L<Coro::AnyEvent> to learn more on how to integrate Coro
58into an event-based environment.
59
52In this module, coroutines are defined as "callchain + lexical variables + 60In this module, a thread is defined as "callchain + lexical variables +
53@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain, 61some package variables + C stack), that is, a thread has its own callchain,
54its own set of lexicals and its own set of perls most important global 62its own set of lexicals and its own set of perls most important global
55variables (see L<Coro::State> for more configuration). 63variables (see L<Coro::State> for more configuration and background info).
64
65See also the C<SEE ALSO> section at the end of this document - the Coro
66module family is quite large.
56 67
57=cut 68=cut
58 69
59package Coro; 70package Coro;
60 71
61use strict qw(vars subs); 72use strict qw(vars subs);
62no warnings "uninitialized"; 73no warnings "uninitialized";
63 74
75use Guard ();
76
64use Coro::State; 77use Coro::State;
65 78
66use base qw(Coro::State Exporter); 79use base qw(Coro::State Exporter);
67 80
68our $idle; # idle handler 81our $idle; # idle handler
69our $main; # main coroutine 82our $main; # main coro
70our $current; # current coroutine 83our $current; # current coro
71 84
72our $VERSION = "5.0"; 85our $VERSION = 5.132;
73 86
74our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); 87our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
75our %EXPORT_TAGS = ( 88our %EXPORT_TAGS = (
76 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], 89 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
77); 90);
78our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready)); 91our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
79 92
93=head1 GLOBAL VARIABLES
94
80=over 4 95=over 4
81 96
82=item $Coro::main 97=item $Coro::main
83 98
84This variable stores the coroutine object that represents the main 99This variable stores the Coro object that represents the main
85program. While you cna C<ready> it and do most other things you can do to 100program. While you cna C<ready> it and do most other things you can do to
86coroutines, it is mainly useful to compare again C<$Coro::current>, to see 101coro, it is mainly useful to compare again C<$Coro::current>, to see
87whether you are running in the main program or not. 102whether you are running in the main program or not.
88 103
89=cut 104=cut
90 105
91# $main is now being initialised by Coro::State 106# $main is now being initialised by Coro::State
92 107
93=item $Coro::current 108=item $Coro::current
94 109
95The coroutine object representing the current coroutine (the last 110The Coro object representing the current coro (the last
96coroutine that the Coro scheduler switched to). The initial value is 111coro that the Coro scheduler switched to). The initial value is
97C<$Coro::main> (of course). 112C<$Coro::main> (of course).
98 113
99This 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
100value 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
101not otherwise modify the variable itself. 116not otherwise modify the variable itself.
102 117
103=cut 118=cut
104 119
105sub current() { $current } # [DEPRECATED] 120sub current() { $current } # [DEPRECATED]
106 121
107=item $Coro::idle 122=item $Coro::idle
108 123
109This 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
110usually 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
111pretty low-level functionality. 126pretty low-level functionality.
112 127
113This 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
114finds no ready coroutines to run. The default implementation prints 131ready coros to run. The default implementation prints "FATAL:
115"FATAL: deadlock detected" and exits, because the program has no other way 132deadlock detected" and exits, because the program has no other way to
116to continue. 133continue.
117 134
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
118This hook is overwritten by modules such as C<Coro::Timer> and 139This hook is overwritten by modules such as C<Coro::EV> and
119C<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
120coroutine so the scheduler can run it. 141coro so the scheduler can run it.
121 142
122Note that the callback I<must not>, under any circumstances, block 143Note that the callback I<must not>, under any circumstances, block
123the current coroutine. Normally, this is achieved by having an "idle 144the current coro. Normally, this is achieved by having an "idle
124coroutine" that calls the event loop and then blocks again, and then 145coro" that calls the event loop and then blocks again, and then
125readying that coroutine in the idle handler. 146readying that coro in the idle handler, or by simply placing the idle
147coro in this variable.
126 148
127See 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
128technique. 150technique.
129 151
130Please 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
… …
135$idle = sub { 157$idle = sub {
136 require Carp; 158 require Carp;
137 Carp::croak ("FATAL: deadlock detected"); 159 Carp::croak ("FATAL: deadlock detected");
138}; 160};
139 161
140# this coroutine is necessary because a coroutine 162# this coro is necessary because a coro
141# cannot destroy itself. 163# cannot destroy itself.
142our @destroy; 164our @destroy;
143our $manager; 165our $manager;
144 166
145$manager = new Coro sub { 167$manager = new Coro sub {
146 while () { 168 while () {
147 Coro::_cancel shift @destroy 169 Coro::State::cancel shift @destroy
148 while @destroy; 170 while @destroy;
149 171
150 &schedule; 172 &schedule;
151 } 173 }
152}; 174};
153$manager->{desc} = "[coro manager]"; 175$manager->{desc} = "[coro manager]";
154$manager->prio (PRIO_MAX); 176$manager->prio (PRIO_MAX);
155 177
156=back 178=back
157 179
158=head2 SIMPLE COROUTINE CREATION 180=head1 SIMPLE CORO CREATION
159 181
160=over 4 182=over 4
161 183
162=item async { ... } [@args...] 184=item async { ... } [@args...]
163 185
164Create a new coroutine and return it's coroutine object (usually 186Create a new coro and return its Coro object (usually
165unused). The coroutine will be put into the ready queue, so 187unused). The coro will be put into the ready queue, so
166it will start running automatically on the next scheduler run. 188it will start running automatically on the next scheduler run.
167 189
168The 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
169coroutine. When it returns argument returns the coroutine is automatically 191coro. When it returns argument returns the coro is automatically
170terminated. 192terminated.
171 193
172The remaining arguments are passed as arguments to the closure. 194The remaining arguments are passed as arguments to the closure.
173 195
174See the C<Coro::State::new> constructor for info about the coroutine 196See the C<Coro::State::new> constructor for info about the coro
175environment in which coroutines are executed. 197environment in which coro are executed.
176 198
177Calling 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
178the coroutine. Likewise, when the coroutine dies, the program will exit, 200the coro. Likewise, when the coro dies, the program will exit,
179just as it would in the main program. 201just as it would in the main program.
180 202
181If 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
182simply avoid dieing (by use of C<eval>). 204simply avoid dieing (by use of C<eval>).
183 205
184Example: Create a new coroutine that just prints its arguments. 206Example: Create a new coro that just prints its arguments.
185 207
186 async { 208 async {
187 print "@_\n"; 209 print "@_\n";
188 } 1,2,3,4; 210 } 1,2,3,4;
189 211
… …
195 $coro 217 $coro
196} 218}
197 219
198=item async_pool { ... } [@args...] 220=item async_pool { ... } [@args...]
199 221
200Similar 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
201terminate 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
202coroutine that might have executed other code already (which can be good 224coro that might have executed other code already (which can be good
203or bad :). 225or bad :).
204 226
205On 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
206destroying) 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
207coroutines in quick successsion, use C<async_pool>, not C<async>. 229coros in quick successsion, use C<async_pool>, not C<async>.
208 230
209The 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
210issued in case of an exception instead of terminating the program, as 232issued in case of an exception instead of terminating the program, as
211C<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>
212will 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,
213which somehow defeats the purpose of pooling (but is fine in the 235which somehow defeats the purpose of pooling (but is fine in the
214exceptional case). 236exceptional case).
215 237
216The 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
217disabled, the description will be reset and the default output filehandle 239disabled, the description will be reset and the default output filehandle
218gets restored, so you can change all these. Otherwise the coroutine will 240gets restored, so you can change all these. Otherwise the coro will
219be 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
220stuff 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
221simply done by using local as in: C<< local $/ >>. 243simply done by using local as in: C<< local $/ >>.
222 244
223The 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
224adjusted 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
225coros as required. 247coros as required.
226 248
227If you are concerned about pooled coroutines growing a lot because a 249If you are concerned about pooled coros growing a lot because a
228single 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
229{ 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
230addition 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
231(adjustable via $Coro::POOL_RSS) it will also be destroyed. 253(adjustable via $Coro::POOL_RSS) it will also be destroyed.
232 254
… …
246 } 268 }
247} 269}
248 270
249=back 271=back
250 272
251=head2 STATIC METHODS 273=head1 STATIC METHODS
252 274
253Static methods are actually functions that operate on the current coroutine. 275Static methods are actually functions that implicitly operate on the
276current coro.
254 277
255=over 4 278=over 4
256 279
257=item schedule 280=item schedule
258 281
259Calls the scheduler. The scheduler will find the next coroutine that is 282Calls the scheduler. The scheduler will find the next coro that is
260to be run from the ready queue and switches to it. The next coroutine 283to be run from the ready queue and switches to it. The next coro
261to be run is simply the one with the highest priority that is longest 284to be run is simply the one with the highest priority that is longest
262in its ready queue. If there is no coroutine ready, it will clal the 285in its ready queue. If there is no coro ready, it will clal the
263C<$Coro::idle> hook. 286C<$Coro::idle> hook.
264 287
265Please 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
266queue, so calling this function usually means you will never be called 289queue, so calling this function usually means you will never be called
267again unless something else (e.g. an event handler) calls C<< ->ready >>, 290again unless something else (e.g. an event handler) calls C<< ->ready >>,
268thus waking you up. 291thus waking you up.
269 292
270This 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
271coroutine and wait for events: first you remember the current coroutine in 294coro and wait for events: first you remember the current coro in
272a 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
273>> 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
274yourself 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,
275so 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
276status in a variable. 299status in a variable.
277 300
278See 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.
279 302
280=item cede 303=item cede
281 304
282"Cede" to other coroutines. This function puts the current coroutine into 305"Cede" to other coros. This function puts the current coro into
283the 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
284up the current "timeslice" to other coroutines of the same or higher 307up the current "timeslice" to other coros of the same or higher
285priority. Once your coroutine gets its turn again it will automatically be 308priority. Once your coro gets its turn again it will automatically be
286resumed. 309resumed.
287 310
288This function is often called C<yield> in other languages. 311This function is often called C<yield> in other languages.
289 312
290=item Coro::cede_notself 313=item Coro::cede_notself
291 314
292Works 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>
293coroutine, regardless of priority. This is useful sometimes to ensure 316coro, regardless of priority. This is useful sometimes to ensure
294progress is made. 317progress is made.
295 318
296=item terminate [arg...] 319=item terminate [arg...]
297 320
298Terminates 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.
299 378
300=item killall 379=item killall
301 380
302Kills/terminates/cancels all coroutines except the currently running 381Kills/terminates/cancels all coros except the currently running one.
303one. This is useful after a fork, either in the child or the parent, as
304usually only one of them should inherit the running coroutines.
305 382
306Note that while this will try to free some of the main programs resources, 383Note that while this will try to free some of the main interpreter
384resources if the calling coro isn't the main coro, but one
307you cannot free all of them, so if a coroutine that is not the main 385cannot free all of them, so if a coro that is not the main coro
308program calls this function, there will be some one-time resource leak. 386calls this function, there will be some one-time resource leak.
309 387
310=cut 388=cut
311 389
312sub killall { 390sub killall {
313 for (Coro::State::list) { 391 for (Coro::State::list) {
… …
316 } 394 }
317} 395}
318 396
319=back 397=back
320 398
321=head2 COROUTINE METHODS 399=head1 CORO OBJECT METHODS
322 400
323These are the methods you can call on coroutine objects (or to create 401These are the methods you can call on coro objects (or to create
324them). 402them).
325 403
326=over 4 404=over 4
327 405
328=item new Coro \&sub [, @args...] 406=item new Coro \&sub [, @args...]
329 407
330Create a new coroutine and return it. When the sub returns, the coroutine 408Create a new coro and return it. When the sub returns, the coro
331automatically terminates as if C<terminate> with the returned values were 409automatically terminates as if C<terminate> with the returned values were
332called. To make the coroutine run you must first put it into the ready 410called. To make the coro run you must first put it into the ready
333queue by calling the ready method. 411queue by calling the ready method.
334 412
335See C<async> and C<Coro::State::new> for additional info about the 413See C<async> and C<Coro::State::new> for additional info about the
336coroutine environment. 414coro environment.
337 415
338=cut 416=cut
339 417
340sub _terminate { 418sub _coro_run {
341 terminate &{+shift}; 419 terminate &{+shift};
342} 420}
343 421
344=item $success = $coroutine->ready 422=item $success = $coro->ready
345 423
346Put the given coroutine into the end of its ready queue (there is one 424Put the given coro into the end of its ready queue (there is one
347queue for each priority) and return true. If the coroutine is already in 425queue for each priority) and return true. If the coro is already in
348the ready queue, do nothing and return false. 426the ready queue, do nothing and return false.
349 427
350This ensures that the scheduler will resume this coroutine automatically 428This ensures that the scheduler will resume this coro automatically
351once all the coroutines of higher priority and all coroutines of the same 429once all the coro of higher priority and all coro of the same
352priority that were put into the ready queue earlier have been resumed. 430priority that were put into the ready queue earlier have been resumed.
353 431
432=item $coro->suspend
433
434Suspends the specified coro. A suspended coro works just like any other
435coro, except that the scheduler will not select a suspended coro for
436execution.
437
438Suspending a coro can be useful when you want to keep the coro from
439running, but you don't want to destroy it, or when you want to temporarily
440freeze a coro (e.g. for debugging) to resume it later.
441
442A scenario for the former would be to suspend all (other) coros after a
443fork and keep them alive, so their destructors aren't called, but new
444coros can be created.
445
446=item $coro->resume
447
448If the specified coro was suspended, it will be resumed. Note that when
449the coro was in the ready queue when it was suspended, it might have been
450unreadied by the scheduler, so an activation might have been lost.
451
452To avoid this, it is best to put a suspended coro into the ready queue
453unconditionally, as every synchronisation mechanism must protect itself
454against spurious wakeups, and the one in the Coro family certainly do
455that.
456
354=item $is_ready = $coroutine->is_ready 457=item $is_ready = $coro->is_ready
355 458
356Return whether the coroutine is currently the ready queue or not, 459Returns true iff the Coro object is in the ready queue. Unless the Coro
460object gets destroyed, it will eventually be scheduled by the scheduler.
357 461
462=item $is_running = $coro->is_running
463
464Returns true iff the Coro object is currently running. Only one Coro object
465can ever be in the running state (but it currently is possible to have
466multiple running Coro::States).
467
468=item $is_suspended = $coro->is_suspended
469
470Returns true iff this Coro object has been suspended. Suspended Coros will
471not ever be scheduled.
472
358=item $coroutine->cancel (arg...) 473=item $coro->cancel (arg...)
359 474
360Terminates the given coroutine and makes it return the given arguments as 475Terminates the given Coro and makes it return the given arguments as
361status (default: the empty list). Never returns if the coroutine is the 476status (default: the empty list). Never returns if the Coro is the
362current coroutine. 477current Coro.
363 478
364=cut 479=cut
365 480
366sub cancel { 481sub cancel {
367 my $self = shift; 482 my $self = shift;
368 483
369 if ($current == $self) { 484 if ($current == $self) {
370 terminate @_; 485 terminate @_;
371 } else { 486 } else {
372 $self->{_status} = [@_]; 487 $self->{_status} = [@_];
373 $self->_cancel; 488 Coro::State::cancel $self;
374 } 489 }
375} 490}
376 491
377=item $coroutine->schedule_to 492=item $coro->schedule_to
378 493
379Puts the current coroutine to sleep (like C<Coro::schedule>), but instead 494Puts the current coro to sleep (like C<Coro::schedule>), but instead
380of continuing with the next coro from the ready queue, always switch to 495of continuing with the next coro from the ready queue, always switch to
381the given coroutine object (regardless of priority etc.). The readyness 496the given coro object (regardless of priority etc.). The readyness
382state of that coroutine isn't changed. 497state of that coro isn't changed.
383 498
384This is an advanced method for special cases - I'd love to hear about any 499This is an advanced method for special cases - I'd love to hear about any
385uses for this one. 500uses for this one.
386 501
387=item $coroutine->cede_to 502=item $coro->cede_to
388 503
389Like C<schedule_to>, but puts the current coroutine into the ready 504Like C<schedule_to>, but puts the current coro into the ready
390queue. This has the effect of temporarily switching to the given 505queue. This has the effect of temporarily switching to the given
391coroutine, and continuing some time later. 506coro, and continuing some time later.
392 507
393This is an advanced method for special cases - I'd love to hear about any 508This is an advanced method for special cases - I'd love to hear about any
394uses for this one. 509uses for this one.
395 510
396=item $coroutine->throw ([$scalar]) 511=item $coro->throw ([$scalar])
397 512
398If C<$throw> is specified and defined, it will be thrown as an exception 513If C<$throw> is specified and defined, it will be thrown as an exception
399inside the coroutine at the next convenient point in time. Otherwise 514inside the coro at the next convenient point in time. Otherwise
400clears the exception object. 515clears the exception object.
401 516
402Coro will check for the exception each time a schedule-like-function 517Coro will check for the exception each time a schedule-like-function
403returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down 518returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down
404>>, C<< Coro::Handle->readable >> and so on. Most of these functions 519>>, C<< Coro::Handle->readable >> and so on. Most of these functions
… …
406 521
407The exception object will be thrown "as is" with the specified scalar in 522The exception object will be thrown "as is" with the specified scalar in
408C<$@>, i.e. if it is a string, no line number or newline will be appended 523C<$@>, i.e. if it is a string, no line number or newline will be appended
409(unlike with C<die>). 524(unlike with C<die>).
410 525
411This can be used as a softer means than C<cancel> to ask a coroutine to 526This can be used as a softer means than C<cancel> to ask a coro to
412end itself, although there is no guarantee that the exception will lead to 527end itself, although there is no guarantee that the exception will lead to
413termination, and if the exception isn't caught it might well end the whole 528termination, and if the exception isn't caught it might well end the whole
414program. 529program.
415 530
416You might also think of C<throw> as being the moral equivalent of 531You might also think of C<throw> as being the moral equivalent of
417C<kill>ing a coroutine with a signal (in this case, a scalar). 532C<kill>ing a coro with a signal (in this case, a scalar).
418 533
419=item $coroutine->join 534=item $coro->join
420 535
421Wait until the coroutine terminates and return any values given to the 536Wait until the coro terminates and return any values given to the
422C<terminate> or C<cancel> functions. C<join> can be called concurrently 537C<terminate> or C<cancel> functions. C<join> can be called concurrently
423from multiple coroutines, and all will be resumed and given the status 538from multiple coro, and all will be resumed and given the status
424return once the C<$coroutine> terminates. 539return once the C<$coro> terminates.
425 540
426=cut 541=cut
427 542
428sub join { 543sub join {
429 my $self = shift; 544 my $self = shift;
… …
440 } 555 }
441 556
442 wantarray ? @{$self->{_status}} : $self->{_status}[0]; 557 wantarray ? @{$self->{_status}} : $self->{_status}[0];
443} 558}
444 559
445=item $coroutine->on_destroy (\&cb) 560=item $coro->on_destroy (\&cb)
446 561
447Registers a callback that is called when this coroutine gets destroyed, 562Registers a callback that is called when this coro gets destroyed,
448but before it is joined. The callback gets passed the terminate arguments, 563but before it is joined. The callback gets passed the terminate arguments,
449if any, and I<must not> die, under any circumstances. 564if any, and I<must not> die, under any circumstances.
450 565
451=cut 566=cut
452 567
… …
454 my ($self, $cb) = @_; 569 my ($self, $cb) = @_;
455 570
456 push @{ $self->{_on_destroy} }, $cb; 571 push @{ $self->{_on_destroy} }, $cb;
457} 572}
458 573
459=item $oldprio = $coroutine->prio ($newprio) 574=item $oldprio = $coro->prio ($newprio)
460 575
461Sets (or gets, if the argument is missing) the priority of the 576Sets (or gets, if the argument is missing) the priority of the
462coroutine. Higher priority coroutines get run before lower priority 577coro. Higher priority coro get run before lower priority
463coroutines. Priorities are small signed integers (currently -4 .. +3), 578coro. Priorities are small signed integers (currently -4 .. +3),
464that you can refer to using PRIO_xxx constants (use the import tag :prio 579that you can refer to using PRIO_xxx constants (use the import tag :prio
465to get then): 580to get then):
466 581
467 PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN 582 PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
468 3 > 1 > 0 > -1 > -3 > -4 583 3 > 1 > 0 > -1 > -3 > -4
469 584
470 # set priority to HIGH 585 # set priority to HIGH
471 current->prio(PRIO_HIGH); 586 current->prio (PRIO_HIGH);
472 587
473The idle coroutine ($Coro::idle) always has a lower priority than any 588The idle coro ($Coro::idle) always has a lower priority than any
474existing coroutine. 589existing coro.
475 590
476Changing the priority of the current coroutine will take effect immediately, 591Changing the priority of the current coro will take effect immediately,
477but changing the priority of coroutines in the ready queue (but not 592but changing the priority of coro in the ready queue (but not
478running) will only take effect after the next schedule (of that 593running) will only take effect after the next schedule (of that
479coroutine). This is a bug that will be fixed in some future version. 594coro). This is a bug that will be fixed in some future version.
480 595
481=item $newprio = $coroutine->nice ($change) 596=item $newprio = $coro->nice ($change)
482 597
483Similar to C<prio>, but subtract the given value from the priority (i.e. 598Similar to C<prio>, but subtract the given value from the priority (i.e.
484higher values mean lower priority, just as in unix). 599higher values mean lower priority, just as in unix).
485 600
486=item $olddesc = $coroutine->desc ($newdesc) 601=item $olddesc = $coro->desc ($newdesc)
487 602
488Sets (or gets in case the argument is missing) the description for this 603Sets (or gets in case the argument is missing) the description for this
489coroutine. This is just a free-form string you can associate with a 604coro. This is just a free-form string you can associate with a
490coroutine. 605coro.
491 606
492This method simply sets the C<< $coroutine->{desc} >> member to the given 607This method simply sets the C<< $coro->{desc} >> member to the given
493string. You can modify this member directly if you wish. 608string. You can modify this member directly if you wish.
494 609
495=cut 610=cut
496 611
497sub desc { 612sub desc {
… …
505 Carp::croak ("You must not call ->transfer on Coro objects. Use Coro::State objects or the ->schedule_to method. Caught"); 620 Carp::croak ("You must not call ->transfer on Coro objects. Use Coro::State objects or the ->schedule_to method. Caught");
506} 621}
507 622
508=back 623=back
509 624
510=head2 GLOBAL FUNCTIONS 625=head1 GLOBAL FUNCTIONS
511 626
512=over 4 627=over 4
513 628
514=item Coro::nready 629=item Coro::nready
515 630
516Returns the number of coroutines that are currently in the ready state, 631Returns the number of coro that are currently in the ready state,
517i.e. that can be switched to by calling C<schedule> directory or 632i.e. that can be switched to by calling C<schedule> directory or
518indirectly. The value C<0> means that the only runnable coroutine is the 633indirectly. The value C<0> means that the only runnable coro is the
519currently running one, so C<cede> would have no effect, and C<schedule> 634currently running one, so C<cede> would have no effect, and C<schedule>
520would cause a deadlock unless there is an idle handler that wakes up some 635would cause a deadlock unless there is an idle handler that wakes up some
521coroutines. 636coro.
522 637
523=item my $guard = Coro::guard { ... } 638=item my $guard = Coro::guard { ... }
524 639
525This creates and returns a guard object. Nothing happens until the object 640This function still exists, but is deprecated. Please use the
526gets destroyed, in which case the codeblock given as argument will be 641C<Guard::guard> function instead.
527executed. This is useful to free locks or other resources in case of a
528runtime error or when the coroutine gets canceled, as in both cases the
529guard block will be executed. The guard object supports only one method,
530C<< ->cancel >>, which will keep the codeblock from being executed.
531 642
532Example: set some flag and clear it again when the coroutine gets canceled
533or the function returns:
534
535 sub do_something {
536 my $guard = Coro::guard { $busy = 0 };
537 $busy = 1;
538
539 # do something that requires $busy to be true
540 }
541
542=cut 643=cut
543 644
544sub guard(&) { 645BEGIN { *guard = \&Guard::guard }
545 bless \(my $cb = $_[0]), "Coro::guard"
546}
547
548sub Coro::guard::cancel {
549 ${$_[0]} = sub { };
550}
551
552sub Coro::guard::DESTROY {
553 ${$_[0]}->();
554}
555
556 646
557=item unblock_sub { ... } 647=item unblock_sub { ... }
558 648
559This utility function takes a BLOCK or code reference and "unblocks" it, 649This utility function takes a BLOCK or code reference and "unblocks" it,
560returning a new coderef. Unblocking means that calling the new coderef 650returning a new coderef. Unblocking means that calling the new coderef
561will return immediately without blocking, returning nothing, while the 651will return immediately without blocking, returning nothing, while the
562original code ref will be called (with parameters) from within another 652original code ref will be called (with parameters) from within another
563coroutine. 653coro.
564 654
565The reason this function exists is that many event libraries (such as the 655The reason this function exists is that many event libraries (such as the
566venerable L<Event|Event> module) are not coroutine-safe (a weaker form 656venerable L<Event|Event> module) are not thread-safe (a weaker form
567of thread-safety). This means you must not block within event callbacks, 657of reentrancy). This means you must not block within event callbacks,
568otherwise you might suffer from crashes or worse. The only event library 658otherwise you might suffer from crashes or worse. The only event library
569currently known that is safe to use without C<unblock_sub> is L<EV>. 659currently known that is safe to use without C<unblock_sub> is L<EV>.
570 660
571This function allows your callbacks to block by executing them in another 661This function allows your callbacks to block by executing them in another
572coroutine where it is safe to block. One example where blocking is handy 662coro where it is safe to block. One example where blocking is handy
573is when you use the L<Coro::AIO|Coro::AIO> functions to save results to 663is when you use the L<Coro::AIO|Coro::AIO> functions to save results to
574disk, for example. 664disk, for example.
575 665
576In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when 666In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
577creating event callbacks that want to block. 667creating event callbacks that want to block.
578 668
579If your handler does not plan to block (e.g. simply sends a message to 669If your handler does not plan to block (e.g. simply sends a message to
580another coroutine, or puts some other coroutine into the ready queue), 670another coro, or puts some other coro into the ready queue), there is
581there is no reason to use C<unblock_sub>. 671no reason to use C<unblock_sub>.
582 672
583Note that you also need to use C<unblock_sub> for any other callbacks that 673Note that you also need to use C<unblock_sub> for any other callbacks that
584are indirectly executed by any C-based event loop. For example, when you 674are indirectly executed by any C-based event loop. For example, when you
585use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it 675use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it
586provides callbacks that are the result of some event callback, then you 676provides callbacks that are the result of some event callback, then you
… …
618 } 708 }
619} 709}
620 710
621=item $cb = Coro::rouse_cb 711=item $cb = Coro::rouse_cb
622 712
623Create and return a "rouse callback". That's a code reference that, when 713Create and return a "rouse callback". That's a code reference that,
624called, will save its arguments and notify the owner coroutine of the 714when called, will remember a copy of its arguments and notify the owner
625callback. 715coro of the callback.
626 716
627See the next function. 717See the next function.
628 718
629=item @args = Coro::rouse_wait [$cb] 719=item @args = Coro::rouse_wait [$cb]
630 720
631Wait for the specified rouse callback (or the last one tht was created in 721Wait for the specified rouse callback (or the last one that was created in
632this coroutine). 722this coro).
633 723
634As soon as the callback is invoked (or when the calback was invoked before 724As soon as the callback is invoked (or when the callback was invoked
635C<rouse_wait>), it will return a copy of the arguments originally passed 725before C<rouse_wait>), it will return the arguments originally passed to
636to the rouse callback. 726the rouse callback.
637 727
638See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example. 728See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example.
639 729
640=back 730=back
641 731
… …
643 733
6441; 7341;
645 735
646=head1 HOW TO WAIT FOR A CALLBACK 736=head1 HOW TO WAIT FOR A CALLBACK
647 737
648It is very common for a coroutine to wait for some callback to be 738It is very common for a coro to wait for some callback to be
649called. This occurs naturally when you use coroutines in an otherwise 739called. This occurs naturally when you use coro in an otherwise
650event-based program, or when you use event-based libraries. 740event-based program, or when you use event-based libraries.
651 741
652These typically register a callback for some event, and call that callback 742These typically register a callback for some event, and call that callback
653when the event occured. In a coroutine, however, you typically want to 743when the event occured. In a coro, however, you typically want to
654just wait for the event, simplyifying things. 744just wait for the event, simplyifying things.
655 745
656For example C<< AnyEvent->child >> registers a callback to be called when 746For example C<< AnyEvent->child >> registers a callback to be called when
657a specific child has exited: 747a specific child has exited:
658 748
659 my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... }); 749 my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... });
660 750
661But from withina coroutine, you often just want to write this: 751But from within a coro, you often just want to write this:
662 752
663 my $status = wait_for_child $pid; 753 my $status = wait_for_child $pid;
664 754
665Coro offers two functions specifically designed to make this easy, 755Coro offers two functions specifically designed to make this easy,
666C<Coro::rouse_cb> and C<Coro::rouse_wait>. 756C<Coro::rouse_cb> and C<Coro::rouse_wait>.
667 757
668The first function, C<rouse_cb>, generates and returns a callback that, 758The first function, C<rouse_cb>, generates and returns a callback that,
669when invoked, will save it's arguments and notify the coroutine that 759when invoked, will save its arguments and notify the coro that
670created the callback. 760created the callback.
671 761
672The second function, C<rouse_wait>, waits for the callback to be called 762The second function, C<rouse_wait>, waits for the callback to be called
673(by calling C<schedule> to go to sleep) and returns the arguments 763(by calling C<schedule> to go to sleep) and returns the arguments
674originally passed to the callback. 764originally passed to the callback.
… …
689you can roll your own, using C<schedule>: 779you can roll your own, using C<schedule>:
690 780
691 sub wait_for_child($) { 781 sub wait_for_child($) {
692 my ($pid) = @_; 782 my ($pid) = @_;
693 783
694 # store the current coroutine in $current, 784 # store the current coro in $current,
695 # and provide result variables for the closure passed to ->child 785 # and provide result variables for the closure passed to ->child
696 my $current = $Coro::current; 786 my $current = $Coro::current;
697 my ($done, $rstatus); 787 my ($done, $rstatus);
698 788
699 # pass a closure to ->child 789 # pass a closure to ->child
… …
715 805
716=item fork with pthread backend 806=item fork with pthread backend
717 807
718When Coro is compiled using the pthread backend (which isn't recommended 808When Coro is compiled using the pthread backend (which isn't recommended
719but required on many BSDs as their libcs are completely broken), then 809but required on many BSDs as their libcs are completely broken), then
720coroutines will not survive a fork. There is no known workaround except to 810coro will not survive a fork. There is no known workaround except to
721fix your libc and use a saner backend. 811fix your libc and use a saner backend.
722 812
723=item perl process emulation ("threads") 813=item perl process emulation ("threads")
724 814
725This module is not perl-pseudo-thread-safe. You should only ever use this 815This module is not perl-pseudo-thread-safe. You should only ever use this
726module from the same thread (this requirement might be removed in the 816module from the first thread (this requirement might be removed in the
727future to allow per-thread schedulers, but Coro::State does not yet allow 817future to allow per-thread schedulers, but Coro::State does not yet allow
728this). I recommend disabling thread support and using processes, as having 818this). I recommend disabling thread support and using processes, as having
729the windows process emulation enabled under unix roughly halves perl 819the windows process emulation enabled under unix roughly halves perl
730performance, even when not used. 820performance, even when not used.
731 821
732=item coroutine switching not signal safe 822=item coro switching is not signal safe
733 823
734You must not switch to another coroutine from within a signal handler 824You must not switch to another coro from within a signal handler
735(only relevant with %SIG - most event libraries provide safe signals). 825(only relevant with %SIG - most event libraries provide safe signals).
736 826
737That means you I<MUST NOT> call any function that might "block" the 827That means you I<MUST NOT> call any function that might "block" the
738current coroutine - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or 828current coro - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or
739anything that calls those. Everything else, including calling C<ready>, 829anything that calls those. Everything else, including calling C<ready>,
740works. 830works.
741 831
742=back 832=back
743 833
… …
748 838
749Debugging: L<Coro::Debug>. 839Debugging: L<Coro::Debug>.
750 840
751Support/Utility: L<Coro::Specific>, L<Coro::Util>. 841Support/Utility: L<Coro::Specific>, L<Coro::Util>.
752 842
753Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>. 843Locking and IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>,
844L<Coro::SemaphoreSet>, L<Coro::RWLock>.
754 845
755IO/Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>. 846I/O and Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>.
756 847
757Compatibility: L<Coro::LWP>, L<Coro::BDB>, L<Coro::Storable>, L<Coro::Select>. 848Compatibility with other modules: L<Coro::LWP> (but see also L<AnyEvent::HTTP> for
849a better-working alternative), L<Coro::BDB>, L<Coro::Storable>,
850L<Coro::Select>.
758 851
759XS API: L<Coro::MakeMaker>. 852XS API: L<Coro::MakeMaker>.
760 853
761Low level Configuration, Coroutine Environment: L<Coro::State>. 854Low level Configuration, Thread Environment, Continuations: L<Coro::State>.
762 855
763=head1 AUTHOR 856=head1 AUTHOR
764 857
765 Marc Lehmann <schmorp@schmorp.de> 858 Marc Lehmann <schmorp@schmorp.de>
766 http://home.schmorp.de/ 859 http://home.schmorp.de/

Diff Legend

– Removed lines
+ Added lines
< Changed lines
> Changed lines