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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), Coro provides a
42full shared address space, which makes communication between coroutines 46full shared address space, which makes communication between threads
43very easy. And coroutines are fast, too: disabling the Windows process 47very easy. And threads are fast, too: disabling the Windows process
44emulation code in your perl and using Coro can easily result in a two to 48emulation code in your perl and using Coro can easily result in a two to
45four times speed increase for your programs. 49four times speed increase for your programs.
46 50
47Coro achieves that by supporting multiple running interpreters that share 51Coro achieves that by supporting multiple running interpreters that share
48data, which is especially useful to code pseudo-parallel processes and 52data, which is especially useful to code pseudo-parallel processes and
49for event-based programming, such as multiple HTTP-GET requests running 53for event-based programming, such as multiple HTTP-GET requests running
50concurrently. See L<Coro::AnyEvent> to learn more on how to integrate Coro 54concurrently. See L<Coro::AnyEvent> to learn more on how to integrate Coro
51into an event-based environment. 55into an event-based environment.
52 56
53In this module, a coroutines is defined as "callchain + lexical variables 57In this module, a thread is defined as "callchain + lexical variables +
54+ @_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own 58@_ + $_ + $@ + $/ + C stack), that is, a thread has its own callchain,
55callchain, its own set of lexicals and its own set of perls most important 59its own set of lexicals and its own set of perls most important global
56global variables (see L<Coro::State> for more configuration and background 60variables (see L<Coro::State> for more configuration and background info).
57info).
58 61
59See also the C<SEE ALSO> section at the end of this document - the Coro 62See also the C<SEE ALSO> section at the end of this document - the Coro
60module family is quite large. 63module family is quite large.
61 64
62=cut 65=cut
64package Coro; 67package Coro;
65 68
66use strict qw(vars subs); 69use strict qw(vars subs);
67no warnings "uninitialized"; 70no warnings "uninitialized";
68 71
72use Guard ();
73
69use Coro::State; 74use Coro::State;
70 75
71use base qw(Coro::State Exporter); 76use base qw(Coro::State Exporter);
72 77
73our $idle; # idle handler 78our $idle; # idle handler
74our $main; # main coroutine 79our $main; # main coro
75our $current; # current coroutine 80our $current; # current coro
76 81
77our $VERSION = "5.0"; 82our $VERSION = 5.13;
78 83
79our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); 84our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
80our %EXPORT_TAGS = ( 85our %EXPORT_TAGS = (
81 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], 86 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
82); 87);
86 91
87=over 4 92=over 4
88 93
89=item $Coro::main 94=item $Coro::main
90 95
91This variable stores the coroutine object that represents the main 96This variable stores the Coro object that represents the main
92program. While you cna C<ready> it and do most other things you can do to 97program. While you cna C<ready> it and do most other things you can do to
93coroutines, it is mainly useful to compare again C<$Coro::current>, to see 98coro, it is mainly useful to compare again C<$Coro::current>, to see
94whether you are running in the main program or not. 99whether you are running in the main program or not.
95 100
96=cut 101=cut
97 102
98# $main is now being initialised by Coro::State 103# $main is now being initialised by Coro::State
99 104
100=item $Coro::current 105=item $Coro::current
101 106
102The coroutine object representing the current coroutine (the last 107The Coro object representing the current coro (the last
103coroutine that the Coro scheduler switched to). The initial value is 108coro that the Coro scheduler switched to). The initial value is
104C<$Coro::main> (of course). 109C<$Coro::main> (of course).
105 110
106This variable is B<strictly> I<read-only>. You can take copies of the 111This 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 112value stored in it and use it as any other Coro object, but you must
108not otherwise modify the variable itself. 113not otherwise modify the variable itself.
109 114
110=cut 115=cut
111 116
112sub current() { $current } # [DEPRECATED] 117sub current() { $current } # [DEPRECATED]
113 118
114=item $Coro::idle 119=item $Coro::idle
115 120
116This variable is mainly useful to integrate Coro into event loops. It is 121This 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 122usually better to rely on L<Coro::AnyEvent> or L<Coro::EV>, as this is
118pretty low-level functionality. 123pretty low-level functionality.
119 124
120This variable stores a callback that is called whenever the scheduler 125This variable stores either a Coro object or a callback.
126
127If it is a callback, the it is called whenever the scheduler finds no
121finds no ready coroutines to run. The default implementation prints 128ready coros to run. The default implementation prints "FATAL:
122"FATAL: deadlock detected" and exits, because the program has no other way 129deadlock detected" and exits, because the program has no other way to
123to continue. 130continue.
124 131
132If it is a coro object, then this object will be readied (without
133invoking any ready hooks, however) when the scheduler finds no other ready
134coros to run.
135
125This hook is overwritten by modules such as C<Coro::Timer> and 136This 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 137C<Coro::AnyEvent> to wait on an external event that hopefully wake up a
127coroutine so the scheduler can run it. 138coro so the scheduler can run it.
128 139
129Note that the callback I<must not>, under any circumstances, block 140Note that the callback I<must not>, under any circumstances, block
130the current coroutine. Normally, this is achieved by having an "idle 141the current coro. Normally, this is achieved by having an "idle
131coroutine" that calls the event loop and then blocks again, and then 142coro" that calls the event loop and then blocks again, and then
132readying that coroutine in the idle handler. 143readying that coro in the idle handler, or by simply placing the idle
144coro in this variable.
133 145
134See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this 146See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this
135technique. 147technique.
136 148
137Please note that if your callback recursively invokes perl (e.g. for event 149Please note that if your callback recursively invokes perl (e.g. for event
142$idle = sub { 154$idle = sub {
143 require Carp; 155 require Carp;
144 Carp::croak ("FATAL: deadlock detected"); 156 Carp::croak ("FATAL: deadlock detected");
145}; 157};
146 158
147# this coroutine is necessary because a coroutine 159# this coro is necessary because a coro
148# cannot destroy itself. 160# cannot destroy itself.
149our @destroy; 161our @destroy;
150our $manager; 162our $manager;
151 163
152$manager = new Coro sub { 164$manager = new Coro sub {
153 while () { 165 while () {
154 Coro::_cancel shift @destroy 166 Coro::State::cancel shift @destroy
155 while @destroy; 167 while @destroy;
156 168
157 &schedule; 169 &schedule;
158 } 170 }
159}; 171};
160$manager->{desc} = "[coro manager]"; 172$manager->{desc} = "[coro manager]";
161$manager->prio (PRIO_MAX); 173$manager->prio (PRIO_MAX);
162 174
163=back 175=back
164 176
165=head1 SIMPLE COROUTINE CREATION 177=head1 SIMPLE CORO CREATION
166 178
167=over 4 179=over 4
168 180
169=item async { ... } [@args...] 181=item async { ... } [@args...]
170 182
171Create a new coroutine and return it's coroutine object (usually 183Create a new coro and return its Coro object (usually
172unused). The coroutine will be put into the ready queue, so 184unused). The coro will be put into the ready queue, so
173it will start running automatically on the next scheduler run. 185it will start running automatically on the next scheduler run.
174 186
175The first argument is a codeblock/closure that should be executed in the 187The first argument is a codeblock/closure that should be executed in the
176coroutine. When it returns argument returns the coroutine is automatically 188coro. When it returns argument returns the coro is automatically
177terminated. 189terminated.
178 190
179The remaining arguments are passed as arguments to the closure. 191The remaining arguments are passed as arguments to the closure.
180 192
181See the C<Coro::State::new> constructor for info about the coroutine 193See the C<Coro::State::new> constructor for info about the coro
182environment in which coroutines are executed. 194environment in which coro are executed.
183 195
184Calling C<exit> in a coroutine will do the same as calling exit outside 196Calling C<exit> in a coro will do the same as calling exit outside
185the coroutine. Likewise, when the coroutine dies, the program will exit, 197the coro. Likewise, when the coro dies, the program will exit,
186just as it would in the main program. 198just as it would in the main program.
187 199
188If you do not want that, you can provide a default C<die> handler, or 200If you do not want that, you can provide a default C<die> handler, or
189simply avoid dieing (by use of C<eval>). 201simply avoid dieing (by use of C<eval>).
190 202
191Example: Create a new coroutine that just prints its arguments. 203Example: Create a new coro that just prints its arguments.
192 204
193 async { 205 async {
194 print "@_\n"; 206 print "@_\n";
195 } 1,2,3,4; 207 } 1,2,3,4;
196 208
202 $coro 214 $coro
203} 215}
204 216
205=item async_pool { ... } [@args...] 217=item async_pool { ... } [@args...]
206 218
207Similar to C<async>, but uses a coroutine pool, so you should not call 219Similar 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 220terminate 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 221coro that might have executed other code already (which can be good
210or bad :). 222or bad :).
211 223
212On the plus side, this function is about twice as fast as creating (and 224On 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 225destroying) a completely new coro, so if you need a lot of generic
214coroutines in quick successsion, use C<async_pool>, not C<async>. 226coros in quick successsion, use C<async_pool>, not C<async>.
215 227
216The code block is executed in an C<eval> context and a warning will be 228The 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 229issued 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> 230C<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, 231will not work in the expected way, unless you call terminate or cancel,
220which somehow defeats the purpose of pooling (but is fine in the 232which somehow defeats the purpose of pooling (but is fine in the
221exceptional case). 233exceptional case).
222 234
223The priority will be reset to C<0> after each run, tracing will be 235The priority will be reset to C<0> after each run, tracing will be
224disabled, the description will be reset and the default output filehandle 236disabled, the description will be reset and the default output filehandle
225gets restored, so you can change all these. Otherwise the coroutine will 237gets 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 238be 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 239stuff such as C<$/> you I<must needs> revert that change, which is most
228simply done by using local as in: C<< local $/ >>. 240simply done by using local as in: C<< local $/ >>.
229 241
230The idle pool size is limited to C<8> idle coroutines (this can be 242The 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 243adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle
232coros as required. 244coros as required.
233 245
234If you are concerned about pooled coroutines growing a lot because a 246If 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 247single 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 248{ 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 249addition to that, when the stacks used by a handler grows larger than 32kb
238(adjustable via $Coro::POOL_RSS) it will also be destroyed. 250(adjustable via $Coro::POOL_RSS) it will also be destroyed.
239 251
256=back 268=back
257 269
258=head1 STATIC METHODS 270=head1 STATIC METHODS
259 271
260Static methods are actually functions that implicitly operate on the 272Static methods are actually functions that implicitly operate on the
261current coroutine. 273current coro.
262 274
263=over 4 275=over 4
264 276
265=item schedule 277=item schedule
266 278
267Calls the scheduler. The scheduler will find the next coroutine that is 279Calls the scheduler. The scheduler will find the next coro that is
268to be run from the ready queue and switches to it. The next coroutine 280to be run from the ready queue and switches to it. The next coro
269to be run is simply the one with the highest priority that is longest 281to be run is simply the one with the highest priority that is longest
270in its ready queue. If there is no coroutine ready, it will clal the 282in its ready queue. If there is no coro ready, it will clal the
271C<$Coro::idle> hook. 283C<$Coro::idle> hook.
272 284
273Please note that the current coroutine will I<not> be put into the ready 285Please 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 286queue, so calling this function usually means you will never be called
275again unless something else (e.g. an event handler) calls C<< ->ready >>, 287again unless something else (e.g. an event handler) calls C<< ->ready >>,
276thus waking you up. 288thus waking you up.
277 289
278This makes C<schedule> I<the> generic method to use to block the current 290This 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 291coro and wait for events: first you remember the current coro in
280a variable, then arrange for some callback of yours to call C<< ->ready 292a 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 293>> 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, 294yourself 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 295so you need to check whether the event indeed happened, e.g. by storing the
284status in a variable. 296status in a variable.
285 297
286See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks. 298See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks.
287 299
288=item cede 300=item cede
289 301
290"Cede" to other coroutines. This function puts the current coroutine into 302"Cede" to other coros. This function puts the current coro into
291the ready queue and calls C<schedule>, which has the effect of giving 303the ready queue and calls C<schedule>, which has the effect of giving
292up the current "timeslice" to other coroutines of the same or higher 304up the current "timeslice" to other coros of the same or higher
293priority. Once your coroutine gets its turn again it will automatically be 305priority. Once your coro gets its turn again it will automatically be
294resumed. 306resumed.
295 307
296This function is often called C<yield> in other languages. 308This function is often called C<yield> in other languages.
297 309
298=item Coro::cede_notself 310=item Coro::cede_notself
299 311
300Works like cede, but is not exported by default and will cede to I<any> 312Works like cede, but is not exported by default and will cede to I<any>
301coroutine, regardless of priority. This is useful sometimes to ensure 313coro, regardless of priority. This is useful sometimes to ensure
302progress is made. 314progress is made.
303 315
304=item terminate [arg...] 316=item terminate [arg...]
305 317
306Terminates the current coroutine with the given status values (see L<cancel>). 318Terminates the current coro with the given status values (see L<cancel>).
319
320=item Coro::on_enter BLOCK, Coro::on_leave BLOCK
321
322These function install enter and leave winders in the current scope. The
323enter block will be executed when on_enter is called and whenever the
324current coro is re-entered by the scheduler, while the leave block is
325executed whenever the current coro is blocked by the scheduler, and
326also when the containing scope is exited (by whatever means, be it exit,
327die, last etc.).
328
329I<Neither invoking the scheduler, nor exceptions, are allowed within those
330BLOCKs>. That means: do not even think about calling C<die> without an
331eval, and do not even think of entering the scheduler in any way.
332
333Since both BLOCKs are tied to the current scope, they will automatically
334be removed when the current scope exits.
335
336These functions implement the same concept as C<dynamic-wind> in scheme
337does, and are useful when you want to localise some resource to a specific
338coro.
339
340They slow down coro switching considerably for coros that use
341them (But coro switching is still reasonably fast if the handlers are
342fast).
343
344These functions are best understood by an example: The following function
345will change the current timezone to "Antarctica/South_Pole", which
346requires a call to C<tzset>, but by using C<on_enter> and C<on_leave>,
347which remember/change the current timezone and restore the previous
348value, respectively, the timezone is only changes for the coro that
349installed those handlers.
350
351 use POSIX qw(tzset);
352
353 async {
354 my $old_tz; # store outside TZ value here
355
356 Coro::on_enter {
357 $old_tz = $ENV{TZ}; # remember the old value
358
359 $ENV{TZ} = "Antarctica/South_Pole";
360 tzset; # enable new value
361 };
362
363 Coro::on_leave {
364 $ENV{TZ} = $old_tz;
365 tzset; # restore old value
366 };
367
368 # at this place, the timezone is Antarctica/South_Pole,
369 # without disturbing the TZ of any other coro.
370 };
371
372This can be used to localise about any resource (locale, uid, current
373working directory etc.) to a block, despite the existance of other
374coros.
307 375
308=item killall 376=item killall
309 377
310Kills/terminates/cancels all coroutines except the currently running 378Kills/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.
313 379
314Note that while this will try to free some of the main programs resources, 380Note that while this will try to free some of the main interpreter
381resources 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 382cannot 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. 383calls this function, there will be some one-time resource leak.
317 384
318=cut 385=cut
319 386
320sub killall { 387sub killall {
321 for (Coro::State::list) { 388 for (Coro::State::list) {
324 } 391 }
325} 392}
326 393
327=back 394=back
328 395
329=head1 COROUTINE OBJECT METHODS 396=head1 CORO OBJECT METHODS
330 397
331These are the methods you can call on coroutine objects (or to create 398These are the methods you can call on coro objects (or to create
332them). 399them).
333 400
334=over 4 401=over 4
335 402
336=item new Coro \&sub [, @args...] 403=item new Coro \&sub [, @args...]
337 404
338Create a new coroutine and return it. When the sub returns, the coroutine 405Create a new coro and return it. When the sub returns, the coro
339automatically terminates as if C<terminate> with the returned values were 406automatically terminates as if C<terminate> with the returned values were
340called. To make the coroutine run you must first put it into the ready 407called. To make the coro run you must first put it into the ready
341queue by calling the ready method. 408queue by calling the ready method.
342 409
343See C<async> and C<Coro::State::new> for additional info about the 410See C<async> and C<Coro::State::new> for additional info about the
344coroutine environment. 411coro environment.
345 412
346=cut 413=cut
347 414
348sub _terminate { 415sub _coro_run {
349 terminate &{+shift}; 416 terminate &{+shift};
350} 417}
351 418
352=item $success = $coroutine->ready 419=item $success = $coro->ready
353 420
354Put the given coroutine into the end of its ready queue (there is one 421Put 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 422queue for each priority) and return true. If the coro is already in
356the ready queue, do nothing and return false. 423the ready queue, do nothing and return false.
357 424
358This ensures that the scheduler will resume this coroutine automatically 425This ensures that the scheduler will resume this coro automatically
359once all the coroutines of higher priority and all coroutines of the same 426once all the coro of higher priority and all coro of the same
360priority that were put into the ready queue earlier have been resumed. 427priority that were put into the ready queue earlier have been resumed.
361 428
362=item $is_ready = $coroutine->is_ready 429=item $is_ready = $coro->is_ready
363 430
364Return whether the coroutine is currently the ready queue or not, 431Returns true iff the Coro object is in the ready queue. Unless the Coro
432object gets destroyed, it will eventually be scheduled by the scheduler.
365 433
434=item $is_running = $coro->is_running
435
436Returns true iff the Coro object is currently running. Only one Coro object
437can ever be in the running state (but it currently is possible to have
438multiple running Coro::States).
439
440=item $is_suspended = $coro->is_suspended
441
442Returns true iff this Coro object has been suspended. Suspended Coros will
443not ever be scheduled.
444
366=item $coroutine->cancel (arg...) 445=item $coro->cancel (arg...)
367 446
368Terminates the given coroutine and makes it return the given arguments as 447Terminates the given Coro and makes it return the given arguments as
369status (default: the empty list). Never returns if the coroutine is the 448status (default: the empty list). Never returns if the Coro is the
370current coroutine. 449current Coro.
371 450
372=cut 451=cut
373 452
374sub cancel { 453sub cancel {
375 my $self = shift; 454 my $self = shift;
376 455
377 if ($current == $self) { 456 if ($current == $self) {
378 terminate @_; 457 terminate @_;
379 } else { 458 } else {
380 $self->{_status} = [@_]; 459 $self->{_status} = [@_];
381 $self->_cancel; 460 Coro::State::cancel $self;
382 } 461 }
383} 462}
384 463
385=item $coroutine->schedule_to 464=item $coro->schedule_to
386 465
387Puts the current coroutine to sleep (like C<Coro::schedule>), but instead 466Puts the current coro to sleep (like C<Coro::schedule>), but instead
388of continuing with the next coro from the ready queue, always switch to 467of continuing with the next coro from the ready queue, always switch to
389the given coroutine object (regardless of priority etc.). The readyness 468the given coro object (regardless of priority etc.). The readyness
390state of that coroutine isn't changed. 469state of that coro isn't changed.
391 470
392This is an advanced method for special cases - I'd love to hear about any 471This is an advanced method for special cases - I'd love to hear about any
393uses for this one. 472uses for this one.
394 473
395=item $coroutine->cede_to 474=item $coro->cede_to
396 475
397Like C<schedule_to>, but puts the current coroutine into the ready 476Like C<schedule_to>, but puts the current coro into the ready
398queue. This has the effect of temporarily switching to the given 477queue. This has the effect of temporarily switching to the given
399coroutine, and continuing some time later. 478coro, and continuing some time later.
400 479
401This is an advanced method for special cases - I'd love to hear about any 480This is an advanced method for special cases - I'd love to hear about any
402uses for this one. 481uses for this one.
403 482
404=item $coroutine->throw ([$scalar]) 483=item $coro->throw ([$scalar])
405 484
406If C<$throw> is specified and defined, it will be thrown as an exception 485If C<$throw> is specified and defined, it will be thrown as an exception
407inside the coroutine at the next convenient point in time. Otherwise 486inside the coro at the next convenient point in time. Otherwise
408clears the exception object. 487clears the exception object.
409 488
410Coro will check for the exception each time a schedule-like-function 489Coro will check for the exception each time a schedule-like-function
411returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down 490returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down
412>>, C<< Coro::Handle->readable >> and so on. Most of these functions 491>>, C<< Coro::Handle->readable >> and so on. Most of these functions
414 493
415The exception object will be thrown "as is" with the specified scalar in 494The exception object will be thrown "as is" with the specified scalar in
416C<$@>, i.e. if it is a string, no line number or newline will be appended 495C<$@>, i.e. if it is a string, no line number or newline will be appended
417(unlike with C<die>). 496(unlike with C<die>).
418 497
419This can be used as a softer means than C<cancel> to ask a coroutine to 498This 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 499end 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 500termination, and if the exception isn't caught it might well end the whole
422program. 501program.
423 502
424You might also think of C<throw> as being the moral equivalent of 503You 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). 504C<kill>ing a coro with a signal (in this case, a scalar).
426 505
427=item $coroutine->join 506=item $coro->join
428 507
429Wait until the coroutine terminates and return any values given to the 508Wait until the coro terminates and return any values given to the
430C<terminate> or C<cancel> functions. C<join> can be called concurrently 509C<terminate> or C<cancel> functions. C<join> can be called concurrently
431from multiple coroutines, and all will be resumed and given the status 510from multiple coro, and all will be resumed and given the status
432return once the C<$coroutine> terminates. 511return once the C<$coro> terminates.
433 512
434=cut 513=cut
435 514
436sub join { 515sub join {
437 my $self = shift; 516 my $self = shift;
448 } 527 }
449 528
450 wantarray ? @{$self->{_status}} : $self->{_status}[0]; 529 wantarray ? @{$self->{_status}} : $self->{_status}[0];
451} 530}
452 531
453=item $coroutine->on_destroy (\&cb) 532=item $coro->on_destroy (\&cb)
454 533
455Registers a callback that is called when this coroutine gets destroyed, 534Registers a callback that is called when this coro gets destroyed,
456but before it is joined. The callback gets passed the terminate arguments, 535but before it is joined. The callback gets passed the terminate arguments,
457if any, and I<must not> die, under any circumstances. 536if any, and I<must not> die, under any circumstances.
458 537
459=cut 538=cut
460 539
462 my ($self, $cb) = @_; 541 my ($self, $cb) = @_;
463 542
464 push @{ $self->{_on_destroy} }, $cb; 543 push @{ $self->{_on_destroy} }, $cb;
465} 544}
466 545
467=item $oldprio = $coroutine->prio ($newprio) 546=item $oldprio = $coro->prio ($newprio)
468 547
469Sets (or gets, if the argument is missing) the priority of the 548Sets (or gets, if the argument is missing) the priority of the
470coroutine. Higher priority coroutines get run before lower priority 549coro. Higher priority coro get run before lower priority
471coroutines. Priorities are small signed integers (currently -4 .. +3), 550coro. Priorities are small signed integers (currently -4 .. +3),
472that you can refer to using PRIO_xxx constants (use the import tag :prio 551that you can refer to using PRIO_xxx constants (use the import tag :prio
473to get then): 552to get then):
474 553
475 PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN 554 PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
476 3 > 1 > 0 > -1 > -3 > -4 555 3 > 1 > 0 > -1 > -3 > -4
477 556
478 # set priority to HIGH 557 # set priority to HIGH
479 current->prio(PRIO_HIGH); 558 current->prio (PRIO_HIGH);
480 559
481The idle coroutine ($Coro::idle) always has a lower priority than any 560The idle coro ($Coro::idle) always has a lower priority than any
482existing coroutine. 561existing coro.
483 562
484Changing the priority of the current coroutine will take effect immediately, 563Changing the priority of the current coro will take effect immediately,
485but changing the priority of coroutines in the ready queue (but not 564but changing the priority of coro in the ready queue (but not
486running) will only take effect after the next schedule (of that 565running) will only take effect after the next schedule (of that
487coroutine). This is a bug that will be fixed in some future version. 566coro). This is a bug that will be fixed in some future version.
488 567
489=item $newprio = $coroutine->nice ($change) 568=item $newprio = $coro->nice ($change)
490 569
491Similar to C<prio>, but subtract the given value from the priority (i.e. 570Similar to C<prio>, but subtract the given value from the priority (i.e.
492higher values mean lower priority, just as in unix). 571higher values mean lower priority, just as in unix).
493 572
494=item $olddesc = $coroutine->desc ($newdesc) 573=item $olddesc = $coro->desc ($newdesc)
495 574
496Sets (or gets in case the argument is missing) the description for this 575Sets (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 576coro. This is just a free-form string you can associate with a
498coroutine. 577coro.
499 578
500This method simply sets the C<< $coroutine->{desc} >> member to the given 579This method simply sets the C<< $coro->{desc} >> member to the given
501string. You can modify this member directly if you wish. 580string. You can modify this member directly if you wish.
502 581
503=cut 582=cut
504 583
505sub desc { 584sub desc {
519 598
520=over 4 599=over 4
521 600
522=item Coro::nready 601=item Coro::nready
523 602
524Returns the number of coroutines that are currently in the ready state, 603Returns the number of coro that are currently in the ready state,
525i.e. that can be switched to by calling C<schedule> directory or 604i.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 605indirectly. 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> 606currently 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 607would cause a deadlock unless there is an idle handler that wakes up some
529coroutines. 608coro.
530 609
531=item my $guard = Coro::guard { ... } 610=item my $guard = Coro::guard { ... }
532 611
533This creates and returns a guard object. Nothing happens until the object 612This function still exists, but is deprecated. Please use the
534gets destroyed, in which case the codeblock given as argument will be 613C<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.
539 614
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 615=cut
551 616
552sub guard(&) { 617BEGIN { *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
564 618
565=item unblock_sub { ... } 619=item unblock_sub { ... }
566 620
567This utility function takes a BLOCK or code reference and "unblocks" it, 621This utility function takes a BLOCK or code reference and "unblocks" it,
568returning a new coderef. Unblocking means that calling the new coderef 622returning a new coderef. Unblocking means that calling the new coderef
569will return immediately without blocking, returning nothing, while the 623will return immediately without blocking, returning nothing, while the
570original code ref will be called (with parameters) from within another 624original code ref will be called (with parameters) from within another
571coroutine. 625coro.
572 626
573The reason this function exists is that many event libraries (such as the 627The reason this function exists is that many event libraries (such as the
574venerable L<Event|Event> module) are not coroutine-safe (a weaker form 628venerable L<Event|Event> module) are not thread-safe (a weaker form
575of thread-safety). This means you must not block within event callbacks, 629of reentrancy). This means you must not block within event callbacks,
576otherwise you might suffer from crashes or worse. The only event library 630otherwise 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>. 631currently known that is safe to use without C<unblock_sub> is L<EV>.
578 632
579This function allows your callbacks to block by executing them in another 633This function allows your callbacks to block by executing them in another
580coroutine where it is safe to block. One example where blocking is handy 634coro 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 635is when you use the L<Coro::AIO|Coro::AIO> functions to save results to
582disk, for example. 636disk, for example.
583 637
584In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when 638In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
585creating event callbacks that want to block. 639creating event callbacks that want to block.
586 640
587If your handler does not plan to block (e.g. simply sends a message to 641If 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), 642another coro, or puts some other coro into the ready queue), there is
589there is no reason to use C<unblock_sub>. 643no reason to use C<unblock_sub>.
590 644
591Note that you also need to use C<unblock_sub> for any other callbacks that 645Note 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 646are 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 647use 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 648provides callbacks that are the result of some event callback, then you
626 } 680 }
627} 681}
628 682
629=item $cb = Coro::rouse_cb 683=item $cb = Coro::rouse_cb
630 684
631Create and return a "rouse callback". That's a code reference that, when 685Create and return a "rouse callback". That's a code reference that,
632called, will save its arguments and notify the owner coroutine of the 686when called, will remember a copy of its arguments and notify the owner
633callback. 687coro of the callback.
634 688
635See the next function. 689See the next function.
636 690
637=item @args = Coro::rouse_wait [$cb] 691=item @args = Coro::rouse_wait [$cb]
638 692
639Wait for the specified rouse callback (or the last one tht was created in 693Wait for the specified rouse callback (or the last one that was created in
640this coroutine). 694this coro).
641 695
642As soon as the callback is invoked (or when the calback was invoked before 696As 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 697before C<rouse_wait>), it will return the arguments originally passed to
644to the rouse callback. 698the rouse callback.
645 699
646See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example. 700See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example.
647 701
648=back 702=back
649 703
651 705
6521; 7061;
653 707
654=head1 HOW TO WAIT FOR A CALLBACK 708=head1 HOW TO WAIT FOR A CALLBACK
655 709
656It is very common for a coroutine to wait for some callback to be 710It is very common for a coro to wait for some callback to be
657called. This occurs naturally when you use coroutines in an otherwise 711called. This occurs naturally when you use coro in an otherwise
658event-based program, or when you use event-based libraries. 712event-based program, or when you use event-based libraries.
659 713
660These typically register a callback for some event, and call that callback 714These typically register a callback for some event, and call that callback
661when the event occured. In a coroutine, however, you typically want to 715when the event occured. In a coro, however, you typically want to
662just wait for the event, simplyifying things. 716just wait for the event, simplyifying things.
663 717
664For example C<< AnyEvent->child >> registers a callback to be called when 718For example C<< AnyEvent->child >> registers a callback to be called when
665a specific child has exited: 719a specific child has exited:
666 720
667 my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... }); 721 my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... });
668 722
669But from withina coroutine, you often just want to write this: 723But from within a coro, you often just want to write this:
670 724
671 my $status = wait_for_child $pid; 725 my $status = wait_for_child $pid;
672 726
673Coro offers two functions specifically designed to make this easy, 727Coro offers two functions specifically designed to make this easy,
674C<Coro::rouse_cb> and C<Coro::rouse_wait>. 728C<Coro::rouse_cb> and C<Coro::rouse_wait>.
675 729
676The first function, C<rouse_cb>, generates and returns a callback that, 730The first function, C<rouse_cb>, generates and returns a callback that,
677when invoked, will save it's arguments and notify the coroutine that 731when invoked, will save its arguments and notify the coro that
678created the callback. 732created the callback.
679 733
680The second function, C<rouse_wait>, waits for the callback to be called 734The second function, C<rouse_wait>, waits for the callback to be called
681(by calling C<schedule> to go to sleep) and returns the arguments 735(by calling C<schedule> to go to sleep) and returns the arguments
682originally passed to the callback. 736originally passed to the callback.
697you can roll your own, using C<schedule>: 751you can roll your own, using C<schedule>:
698 752
699 sub wait_for_child($) { 753 sub wait_for_child($) {
700 my ($pid) = @_; 754 my ($pid) = @_;
701 755
702 # store the current coroutine in $current, 756 # store the current coro in $current,
703 # and provide result variables for the closure passed to ->child 757 # and provide result variables for the closure passed to ->child
704 my $current = $Coro::current; 758 my $current = $Coro::current;
705 my ($done, $rstatus); 759 my ($done, $rstatus);
706 760
707 # pass a closure to ->child 761 # pass a closure to ->child
723 777
724=item fork with pthread backend 778=item fork with pthread backend
725 779
726When Coro is compiled using the pthread backend (which isn't recommended 780When Coro is compiled using the pthread backend (which isn't recommended
727but required on many BSDs as their libcs are completely broken), then 781but required on many BSDs as their libcs are completely broken), then
728coroutines will not survive a fork. There is no known workaround except to 782coro will not survive a fork. There is no known workaround except to
729fix your libc and use a saner backend. 783fix your libc and use a saner backend.
730 784
731=item perl process emulation ("threads") 785=item perl process emulation ("threads")
732 786
733This module is not perl-pseudo-thread-safe. You should only ever use this 787This 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 788module from the first thread (this requirement might be removed in the
735future to allow per-thread schedulers, but Coro::State does not yet allow 789future to allow per-thread schedulers, but Coro::State does not yet allow
736this). I recommend disabling thread support and using processes, as having 790this). I recommend disabling thread support and using processes, as having
737the windows process emulation enabled under unix roughly halves perl 791the windows process emulation enabled under unix roughly halves perl
738performance, even when not used. 792performance, even when not used.
739 793
740=item coroutine switching not signal safe 794=item coro switching is not signal safe
741 795
742You must not switch to another coroutine from within a signal handler 796You must not switch to another coro from within a signal handler
743(only relevant with %SIG - most event libraries provide safe signals). 797(only relevant with %SIG - most event libraries provide safe signals).
744 798
745That means you I<MUST NOT> call any function that might "block" the 799That means you I<MUST NOT> call any function that might "block" the
746current coroutine - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or 800current coro - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or
747anything that calls those. Everything else, including calling C<ready>, 801anything that calls those. Everything else, including calling C<ready>,
748works. 802works.
749 803
750=back 804=back
751 805
756 810
757Debugging: L<Coro::Debug>. 811Debugging: L<Coro::Debug>.
758 812
759Support/Utility: L<Coro::Specific>, L<Coro::Util>. 813Support/Utility: L<Coro::Specific>, L<Coro::Util>.
760 814
761Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>. 815Locking and IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>,
816L<Coro::SemaphoreSet>, L<Coro::RWLock>.
762 817
763IO/Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>. 818I/O and Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>.
764 819
765Compatibility: L<Coro::LWP>, L<Coro::BDB>, L<Coro::Storable>, L<Coro::Select>. 820Compatibility with other modules: L<Coro::LWP> (but see also L<AnyEvent::HTTP> for
821a better-working alternative), L<Coro::BDB>, L<Coro::Storable>,
822L<Coro::Select>.
766 823
767XS API: L<Coro::MakeMaker>. 824XS API: L<Coro::MakeMaker>.
768 825
769Low level Configuration, Coroutine Environment: L<Coro::State>. 826Low level Configuration, Thread Environment, Continuations: L<Coro::State>.
770 827
771=head1 AUTHOR 828=head1 AUTHOR
772 829
773 Marc Lehmann <schmorp@schmorp.de> 830 Marc Lehmann <schmorp@schmorp.de>
774 http://home.schmorp.de/ 831 http://home.schmorp.de/

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