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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 $VERSION = 5.162;
73 86
74our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); 87our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
75our %EXPORT_TAGS = ( 88our %EXPORT_TAGS = (
76 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], 89 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
77); 90);
78our @EXPORT_OK = (@{$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$idle = sub {
136 require Carp; 158 require Carp;
137 Carp::croak ("FATAL: deadlock detected"); 159 Carp::croak ("FATAL: deadlock detected");
138}; 160};
139 161
140sub _cancel {
141 my ($self) = @_;
142
143 # free coroutine data and mark as destructed
144 $self->_destroy
145 or return;
146
147 # call all destruction callbacks
148 $_->(@{$self->{_status}})
149 for @{ delete $self->{_on_destroy} || [] };
150}
151
152# this coroutine is necessary because a coroutine 162# this coro is necessary because a coro
153# cannot destroy itself. 163# cannot destroy itself.
154our @destroy; 164our @destroy;
155our $manager; 165our $manager;
156 166
157$manager = new Coro sub { 167$manager = new Coro sub {
158 while () { 168 while () {
159 (shift @destroy)->_cancel 169 Coro::State::cancel shift @destroy
160 while @destroy; 170 while @destroy;
161 171
162 &schedule; 172 &schedule;
163 } 173 }
164}; 174};
165$manager->{desc} = "[coro manager]"; 175$manager->{desc} = "[coro manager]";
166$manager->prio (PRIO_MAX); 176$manager->prio (PRIO_MAX);
167 177
168=back 178=back
169 179
170=head2 SIMPLE COROUTINE CREATION 180=head1 SIMPLE CORO CREATION
171 181
172=over 4 182=over 4
173 183
174=item async { ... } [@args...] 184=item async { ... } [@args...]
175 185
176Create a new coroutine and return it's coroutine object (usually 186Create a new coro and return its Coro object (usually
177unused). The coroutine will be put into the ready queue, so 187unused). The coro will be put into the ready queue, so
178it will start running automatically on the next scheduler run. 188it will start running automatically on the next scheduler run.
179 189
180The 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
181coroutine. When it returns argument returns the coroutine is automatically 191coro. When it returns argument returns the coro is automatically
182terminated. 192terminated.
183 193
184The remaining arguments are passed as arguments to the closure. 194The remaining arguments are passed as arguments to the closure.
185 195
186See the C<Coro::State::new> constructor for info about the coroutine 196See the C<Coro::State::new> constructor for info about the coro
187environment in which coroutines are executed. 197environment in which coro are executed.
188 198
189Calling 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
190the coroutine. Likewise, when the coroutine dies, the program will exit, 200the coro. Likewise, when the coro dies, the program will exit,
191just as it would in the main program. 201just as it would in the main program.
192 202
193If 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
194simply avoid dieing (by use of C<eval>). 204simply avoid dieing (by use of C<eval>).
195 205
196Example: Create a new coroutine that just prints its arguments. 206Example: Create a new coro that just prints its arguments.
197 207
198 async { 208 async {
199 print "@_\n"; 209 print "@_\n";
200 } 1,2,3,4; 210 } 1,2,3,4;
201 211
… …
207 $coro 217 $coro
208} 218}
209 219
210=item async_pool { ... } [@args...] 220=item async_pool { ... } [@args...]
211 221
212Similar 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
213terminate 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
214coroutine that might have executed other code already (which can be good 224coro that might have executed other code already (which can be good
215or bad :). 225or bad :).
216 226
217On 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
218destroying) 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
219coroutines in quick successsion, use C<async_pool>, not C<async>. 229coros in quick successsion, use C<async_pool>, not C<async>.
220 230
221The 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
222issued in case of an exception instead of terminating the program, as 232issued in case of an exception instead of terminating the program, as
223C<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>
224will 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,
225which somehow defeats the purpose of pooling (but is fine in the 235which somehow defeats the purpose of pooling (but is fine in the
226exceptional case). 236exceptional case).
227 237
228The 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
229disabled, the description will be reset and the default output filehandle 239disabled, the description will be reset and the default output filehandle
230gets restored, so you can change all these. Otherwise the coroutine will 240gets restored, so you can change all these. Otherwise the coro will
231be 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
232stuff 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
233simply done by using local as in: C<< local $/ >>. 243simply done by using local as in: C<< local $/ >>.
234 244
235The 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
236adjusted 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
237coros as required. 247coros as required.
238 248
239If you are concerned about pooled coroutines growing a lot because a 249If you are concerned about pooled coros growing a lot because a
240single 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
241{ 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
242addition to that, when the stacks used by a handler grows larger than 16kb 252addition to that, when the stacks used by a handler grows larger than 32kb
243(adjustable via $Coro::POOL_RSS) it will also be destroyed. 253(adjustable via $Coro::POOL_RSS) it will also be destroyed.
244 254
245=cut 255=cut
246 256
247our $POOL_SIZE = 8; 257our $POOL_SIZE = 8;
248our $POOL_RSS = 16 * 1024; 258our $POOL_RSS = 32 * 1024;
249our @async_pool; 259our @async_pool;
250 260
251sub pool_handler { 261sub pool_handler {
252 while () { 262 while () {
253 eval { 263 eval {
… …
258 } 268 }
259} 269}
260 270
261=back 271=back
262 272
263=head2 STATIC METHODS 273=head1 STATIC METHODS
264 274
265Static methods are actually functions that operate on the current coroutine. 275Static methods are actually functions that implicitly operate on the
276current coro.
266 277
267=over 4 278=over 4
268 279
269=item schedule 280=item schedule
270 281
271Calls the scheduler. The scheduler will find the next coroutine that is 282Calls the scheduler. The scheduler will find the next coro that is
272to be run from the ready queue and switches to it. The next coroutine 283to be run from the ready queue and switches to it. The next coro
273to be run is simply the one with the highest priority that is longest 284to be run is simply the one with the highest priority that is longest
274in its ready queue. If there is no coroutine ready, it will clal the 285in its ready queue. If there is no coro ready, it will clal the
275C<$Coro::idle> hook. 286C<$Coro::idle> hook.
276 287
277Please 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
278queue, so calling this function usually means you will never be called 289queue, so calling this function usually means you will never be called
279again unless something else (e.g. an event handler) calls C<< ->ready >>, 290again unless something else (e.g. an event handler) calls C<< ->ready >>,
280thus waking you up. 291thus waking you up.
281 292
282This 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
283coroutine and wait for events: first you remember the current coroutine in 294coro and wait for events: first you remember the current coro in
284a 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
285>> 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
286yourself 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,
287so 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
288status in a variable. 299status in a variable.
289 300
290See 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.
291 302
292=item cede 303=item cede
293 304
294"Cede" to other coroutines. This function puts the current coroutine into 305"Cede" to other coros. This function puts the current coro into
295the 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
296up the current "timeslice" to other coroutines of the same or higher 307up the current "timeslice" to other coros of the same or higher
297priority. Once your coroutine gets its turn again it will automatically be 308priority. Once your coro gets its turn again it will automatically be
298resumed. 309resumed.
299 310
300This function is often called C<yield> in other languages. 311This function is often called C<yield> in other languages.
301 312
302=item Coro::cede_notself 313=item Coro::cede_notself
303 314
304Works 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>
305coroutine, regardless of priority. This is useful sometimes to ensure 316coro, regardless of priority. This is useful sometimes to ensure
306progress is made. 317progress is made.
307 318
308=item terminate [arg...] 319=item terminate [arg...]
309 320
310Terminates the current coroutine with the given status values (see L<cancel>). 321Terminates the current coro with the given status values (see L<cancel>).
322
323=item Coro::on_enter BLOCK, Coro::on_leave BLOCK
324
325These function install enter and leave winders in the current scope. The
326enter block will be executed when on_enter is called and whenever the
327current coro is re-entered by the scheduler, while the leave block is
328executed whenever the current coro is blocked by the scheduler, and
329also when the containing scope is exited (by whatever means, be it exit,
330die, last etc.).
331
332I<Neither invoking the scheduler, nor exceptions, are allowed within those
333BLOCKs>. That means: do not even think about calling C<die> without an
334eval, and do not even think of entering the scheduler in any way.
335
336Since both BLOCKs are tied to the current scope, they will automatically
337be removed when the current scope exits.
338
339These functions implement the same concept as C<dynamic-wind> in scheme
340does, and are useful when you want to localise some resource to a specific
341coro.
342
343They slow down thread switching considerably for coros that use them
344(about 40% for a BLOCK with a single assignment, so thread switching is
345still reasonably fast if the handlers are fast).
346
347These functions are best understood by an example: The following function
348will change the current timezone to "Antarctica/South_Pole", which
349requires a call to C<tzset>, but by using C<on_enter> and C<on_leave>,
350which remember/change the current timezone and restore the previous
351value, respectively, the timezone is only changed for the coro that
352installed those handlers.
353
354 use POSIX qw(tzset);
355
356 async {
357 my $old_tz; # store outside TZ value here
358
359 Coro::on_enter {
360 $old_tz = $ENV{TZ}; # remember the old value
361
362 $ENV{TZ} = "Antarctica/South_Pole";
363 tzset; # enable new value
364 };
365
366 Coro::on_leave {
367 $ENV{TZ} = $old_tz;
368 tzset; # restore old value
369 };
370
371 # at this place, the timezone is Antarctica/South_Pole,
372 # without disturbing the TZ of any other coro.
373 };
374
375This can be used to localise about any resource (locale, uid, current
376working directory etc.) to a block, despite the existance of other
377coros.
378
379Another interesting example implements time-sliced multitasking using
380interval timers (this could obviously be optimised, but does the job):
381
382 # "timeslice" the given block
383 sub timeslice(&) {
384 use Time::HiRes ();
385
386 Coro::on_enter {
387 # on entering the thread, we set an VTALRM handler to cede
388 $SIG{VTALRM} = sub { cede };
389 # and then start the interval timer
390 Time::HiRes::setitimer &Time::HiRes::ITIMER_VIRTUAL, 0.01, 0.01;
391 };
392 Coro::on_leave {
393 # on leaving the thread, we stop the interval timer again
394 Time::HiRes::setitimer &Time::HiRes::ITIMER_VIRTUAL, 0, 0;
395 };
396
397 &{+shift};
398 }
399
400 # use like this:
401 timeslice {
402 # The following is an endless loop that would normally
403 # monopolise the process. Since it runs in a timesliced
404 # environment, it will regularly cede to other threads.
405 while () { }
406 };
407
311 408
312=item killall 409=item killall
313 410
314Kills/terminates/cancels all coroutines except the currently running 411Kills/terminates/cancels all coros except the currently running one.
315one. This is useful after a fork, either in the child or the parent, as
316usually only one of them should inherit the running coroutines.
317 412
318Note that while this will try to free some of the main programs resources, 413Note that while this will try to free some of the main interpreter
414resources if the calling coro isn't the main coro, but one
319you cannot free all of them, so if a coroutine that is not the main 415cannot free all of them, so if a coro that is not the main coro
320program calls this function, there will be some one-time resource leak. 416calls this function, there will be some one-time resource leak.
321 417
322=cut 418=cut
323
324sub terminate {
325 $current->{_status} = [@_];
326 push @destroy, $current;
327 $manager->ready;
328 do { &schedule } while 1;
329}
330 419
331sub killall { 420sub killall {
332 for (Coro::State::list) { 421 for (Coro::State::list) {
333 $_->cancel 422 $_->cancel
334 if $_ != $current && UNIVERSAL::isa $_, "Coro"; 423 if $_ != $current && UNIVERSAL::isa $_, "Coro";
335 } 424 }
336} 425}
337 426
338=back 427=back
339 428
340=head2 COROUTINE METHODS 429=head1 CORO OBJECT METHODS
341 430
342These are the methods you can call on coroutine objects (or to create 431These are the methods you can call on coro objects (or to create
343them). 432them).
344 433
345=over 4 434=over 4
346 435
347=item new Coro \&sub [, @args...] 436=item new Coro \&sub [, @args...]
348 437
349Create a new coroutine and return it. When the sub returns, the coroutine 438Create a new coro and return it. When the sub returns, the coro
350automatically terminates as if C<terminate> with the returned values were 439automatically terminates as if C<terminate> with the returned values were
351called. To make the coroutine run you must first put it into the ready 440called. To make the coro run you must first put it into the ready
352queue by calling the ready method. 441queue by calling the ready method.
353 442
354See C<async> and C<Coro::State::new> for additional info about the 443See C<async> and C<Coro::State::new> for additional info about the
355coroutine environment. 444coro environment.
356 445
357=cut 446=cut
358 447
359sub _terminate { 448sub _coro_run {
360 terminate &{+shift}; 449 terminate &{+shift};
361} 450}
362 451
363=item $success = $coroutine->ready 452=item $success = $coro->ready
364 453
365Put the given coroutine into the end of its ready queue (there is one 454Put the given coro into the end of its ready queue (there is one
366queue for each priority) and return true. If the coroutine is already in 455queue for each priority) and return true. If the coro is already in
367the ready queue, do nothing and return false. 456the ready queue, do nothing and return false.
368 457
369This ensures that the scheduler will resume this coroutine automatically 458This ensures that the scheduler will resume this coro automatically
370once all the coroutines of higher priority and all coroutines of the same 459once all the coro of higher priority and all coro of the same
371priority that were put into the ready queue earlier have been resumed. 460priority that were put into the ready queue earlier have been resumed.
372 461
462=item $coro->suspend
463
464Suspends the specified coro. A suspended coro works just like any other
465coro, except that the scheduler will not select a suspended coro for
466execution.
467
468Suspending a coro can be useful when you want to keep the coro from
469running, but you don't want to destroy it, or when you want to temporarily
470freeze a coro (e.g. for debugging) to resume it later.
471
472A scenario for the former would be to suspend all (other) coros after a
473fork and keep them alive, so their destructors aren't called, but new
474coros can be created.
475
476=item $coro->resume
477
478If the specified coro was suspended, it will be resumed. Note that when
479the coro was in the ready queue when it was suspended, it might have been
480unreadied by the scheduler, so an activation might have been lost.
481
482To avoid this, it is best to put a suspended coro into the ready queue
483unconditionally, as every synchronisation mechanism must protect itself
484against spurious wakeups, and the one in the Coro family certainly do
485that.
486
373=item $is_ready = $coroutine->is_ready 487=item $is_ready = $coro->is_ready
374 488
375Return whether the coroutine is currently the ready queue or not, 489Returns true iff the Coro object is in the ready queue. Unless the Coro
490object gets destroyed, it will eventually be scheduled by the scheduler.
376 491
492=item $is_running = $coro->is_running
493
494Returns true iff the Coro object is currently running. Only one Coro object
495can ever be in the running state (but it currently is possible to have
496multiple running Coro::States).
497
498=item $is_suspended = $coro->is_suspended
499
500Returns true iff this Coro object has been suspended. Suspended Coros will
501not ever be scheduled.
502
377=item $coroutine->cancel (arg...) 503=item $coro->cancel (arg...)
378 504
379Terminates the given coroutine and makes it return the given arguments as 505Terminates the given Coro and makes it return the given arguments as
380status (default: the empty list). Never returns if the coroutine is the 506status (default: the empty list). Never returns if the Coro is the
381current coroutine. 507current Coro.
382 508
383=cut 509=cut
384 510
385sub cancel { 511sub cancel {
386 my $self = shift; 512 my $self = shift;
387 513
388 if ($current == $self) { 514 if ($current == $self) {
389 terminate @_; 515 terminate @_;
390 } else { 516 } else {
391 $self->{_status} = [@_]; 517 $self->{_status} = [@_];
392 $self->_cancel; 518 Coro::State::cancel $self;
393 } 519 }
394} 520}
395 521
396=item $coroutine->schedule_to 522=item $coro->schedule_to
397 523
398Puts the current coroutine to sleep (like C<Coro::schedule>), but instead 524Puts the current coro to sleep (like C<Coro::schedule>), but instead
399of continuing with the next coro from the ready queue, always switch to 525of continuing with the next coro from the ready queue, always switch to
400the given coroutine object (regardless of priority etc.). The readyness 526the given coro object (regardless of priority etc.). The readyness
401state of that coroutine isn't changed. 527state of that coro isn't changed.
402 528
403This is an advanced method for special cases - I'd love to hear about any 529This is an advanced method for special cases - I'd love to hear about any
404uses for this one. 530uses for this one.
405 531
406=item $coroutine->cede_to 532=item $coro->cede_to
407 533
408Like C<schedule_to>, but puts the current coroutine into the ready 534Like C<schedule_to>, but puts the current coro into the ready
409queue. This has the effect of temporarily switching to the given 535queue. This has the effect of temporarily switching to the given
410coroutine, and continuing some time later. 536coro, and continuing some time later.
411 537
412This is an advanced method for special cases - I'd love to hear about any 538This is an advanced method for special cases - I'd love to hear about any
413uses for this one. 539uses for this one.
414 540
415=item $coroutine->throw ([$scalar]) 541=item $coro->throw ([$scalar])
416 542
417If C<$throw> is specified and defined, it will be thrown as an exception 543If C<$throw> is specified and defined, it will be thrown as an exception
418inside the coroutine at the next convenient point in time. Otherwise 544inside the coro at the next convenient point in time. Otherwise
419clears the exception object. 545clears the exception object.
420 546
421Coro will check for the exception each time a schedule-like-function 547Coro will check for the exception each time a schedule-like-function
422returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down 548returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down
423>>, C<< Coro::Handle->readable >> and so on. Most of these functions 549>>, C<< Coro::Handle->readable >> and so on. Most of these functions
… …
425 551
426The exception object will be thrown "as is" with the specified scalar in 552The exception object will be thrown "as is" with the specified scalar in
427C<$@>, i.e. if it is a string, no line number or newline will be appended 553C<$@>, i.e. if it is a string, no line number or newline will be appended
428(unlike with C<die>). 554(unlike with C<die>).
429 555
430This can be used as a softer means than C<cancel> to ask a coroutine to 556This can be used as a softer means than C<cancel> to ask a coro to
431end itself, although there is no guarantee that the exception will lead to 557end itself, although there is no guarantee that the exception will lead to
432termination, and if the exception isn't caught it might well end the whole 558termination, and if the exception isn't caught it might well end the whole
433program. 559program.
434 560
435You might also think of C<throw> as being the moral equivalent of 561You might also think of C<throw> as being the moral equivalent of
436C<kill>ing a coroutine with a signal (in this case, a scalar). 562C<kill>ing a coro with a signal (in this case, a scalar).
437 563
438=item $coroutine->join 564=item $coro->join
439 565
440Wait until the coroutine terminates and return any values given to the 566Wait until the coro terminates and return any values given to the
441C<terminate> or C<cancel> functions. C<join> can be called concurrently 567C<terminate> or C<cancel> functions. C<join> can be called concurrently
442from multiple coroutines, and all will be resumed and given the status 568from multiple coro, and all will be resumed and given the status
443return once the C<$coroutine> terminates. 569return once the C<$coro> terminates.
444 570
445=cut 571=cut
446 572
447sub join { 573sub join {
448 my $self = shift; 574 my $self = shift;
… …
459 } 585 }
460 586
461 wantarray ? @{$self->{_status}} : $self->{_status}[0]; 587 wantarray ? @{$self->{_status}} : $self->{_status}[0];
462} 588}
463 589
464=item $coroutine->on_destroy (\&cb) 590=item $coro->on_destroy (\&cb)
465 591
466Registers a callback that is called when this coroutine gets destroyed, 592Registers a callback that is called when this coro gets destroyed,
467but before it is joined. The callback gets passed the terminate arguments, 593but before it is joined. The callback gets passed the terminate arguments,
468if any, and I<must not> die, under any circumstances. 594if any, and I<must not> die, under any circumstances.
469 595
470=cut 596=cut
471 597
… …
473 my ($self, $cb) = @_; 599 my ($self, $cb) = @_;
474 600
475 push @{ $self->{_on_destroy} }, $cb; 601 push @{ $self->{_on_destroy} }, $cb;
476} 602}
477 603
478=item $oldprio = $coroutine->prio ($newprio) 604=item $oldprio = $coro->prio ($newprio)
479 605
480Sets (or gets, if the argument is missing) the priority of the 606Sets (or gets, if the argument is missing) the priority of the
481coroutine. Higher priority coroutines get run before lower priority 607coro. Higher priority coro get run before lower priority
482coroutines. Priorities are small signed integers (currently -4 .. +3), 608coro. Priorities are small signed integers (currently -4 .. +3),
483that you can refer to using PRIO_xxx constants (use the import tag :prio 609that you can refer to using PRIO_xxx constants (use the import tag :prio
484to get then): 610to get then):
485 611
486 PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN 612 PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
487 3 > 1 > 0 > -1 > -3 > -4 613 3 > 1 > 0 > -1 > -3 > -4
488 614
489 # set priority to HIGH 615 # set priority to HIGH
490 current->prio(PRIO_HIGH); 616 current->prio (PRIO_HIGH);
491 617
492The idle coroutine ($Coro::idle) always has a lower priority than any 618The idle coro ($Coro::idle) always has a lower priority than any
493existing coroutine. 619existing coro.
494 620
495Changing the priority of the current coroutine will take effect immediately, 621Changing the priority of the current coro will take effect immediately,
496but changing the priority of coroutines in the ready queue (but not 622but changing the priority of coro in the ready queue (but not
497running) will only take effect after the next schedule (of that 623running) will only take effect after the next schedule (of that
498coroutine). This is a bug that will be fixed in some future version. 624coro). This is a bug that will be fixed in some future version.
499 625
500=item $newprio = $coroutine->nice ($change) 626=item $newprio = $coro->nice ($change)
501 627
502Similar to C<prio>, but subtract the given value from the priority (i.e. 628Similar to C<prio>, but subtract the given value from the priority (i.e.
503higher values mean lower priority, just as in unix). 629higher values mean lower priority, just as in unix).
504 630
505=item $olddesc = $coroutine->desc ($newdesc) 631=item $olddesc = $coro->desc ($newdesc)
506 632
507Sets (or gets in case the argument is missing) the description for this 633Sets (or gets in case the argument is missing) the description for this
508coroutine. This is just a free-form string you can associate with a 634coro. This is just a free-form string you can associate with a
509coroutine. 635coro.
510 636
511This method simply sets the C<< $coroutine->{desc} >> member to the given 637This method simply sets the C<< $coro->{desc} >> member to the given
512string. You can modify this member directly if you wish. 638string. You can modify this member directly if you wish.
513 639
514=cut 640=cut
515 641
516sub desc { 642sub desc {
517 my $old = $_[0]{desc}; 643 my $old = $_[0]{desc};
518 $_[0]{desc} = $_[1] if @_ > 1; 644 $_[0]{desc} = $_[1] if @_ > 1;
519 $old; 645 $old;
520} 646}
521 647
648sub transfer {
649 require Carp;
650 Carp::croak ("You must not call ->transfer on Coro objects. Use Coro::State objects or the ->schedule_to method. Caught");
651}
652
522=back 653=back
523 654
524=head2 GLOBAL FUNCTIONS 655=head1 GLOBAL FUNCTIONS
525 656
526=over 4 657=over 4
527 658
528=item Coro::nready 659=item Coro::nready
529 660
530Returns the number of coroutines that are currently in the ready state, 661Returns the number of coro that are currently in the ready state,
531i.e. that can be switched to by calling C<schedule> directory or 662i.e. that can be switched to by calling C<schedule> directory or
532indirectly. The value C<0> means that the only runnable coroutine is the 663indirectly. The value C<0> means that the only runnable coro is the
533currently running one, so C<cede> would have no effect, and C<schedule> 664currently running one, so C<cede> would have no effect, and C<schedule>
534would cause a deadlock unless there is an idle handler that wakes up some 665would cause a deadlock unless there is an idle handler that wakes up some
535coroutines. 666coro.
536 667
537=item my $guard = Coro::guard { ... } 668=item my $guard = Coro::guard { ... }
538 669
539This creates and returns a guard object. Nothing happens until the object 670This function still exists, but is deprecated. Please use the
540gets destroyed, in which case the codeblock given as argument will be 671C<Guard::guard> function instead.
541executed. This is useful to free locks or other resources in case of a
542runtime error or when the coroutine gets canceled, as in both cases the
543guard block will be executed. The guard object supports only one method,
544C<< ->cancel >>, which will keep the codeblock from being executed.
545 672
546Example: set some flag and clear it again when the coroutine gets canceled
547or the function returns:
548
549 sub do_something {
550 my $guard = Coro::guard { $busy = 0 };
551 $busy = 1;
552
553 # do something that requires $busy to be true
554 }
555
556=cut 673=cut
557 674
558sub guard(&) { 675BEGIN { *guard = \&Guard::guard }
559 bless \(my $cb = $_[0]), "Coro::guard"
560}
561
562sub Coro::guard::cancel {
563 ${$_[0]} = sub { };
564}
565
566sub Coro::guard::DESTROY {
567 ${$_[0]}->();
568}
569
570 676
571=item unblock_sub { ... } 677=item unblock_sub { ... }
572 678
573This utility function takes a BLOCK or code reference and "unblocks" it, 679This utility function takes a BLOCK or code reference and "unblocks" it,
574returning a new coderef. Unblocking means that calling the new coderef 680returning a new coderef. Unblocking means that calling the new coderef
575will return immediately without blocking, returning nothing, while the 681will return immediately without blocking, returning nothing, while the
576original code ref will be called (with parameters) from within another 682original code ref will be called (with parameters) from within another
577coroutine. 683coro.
578 684
579The reason this function exists is that many event libraries (such as the 685The reason this function exists is that many event libraries (such as the
580venerable L<Event|Event> module) are not coroutine-safe (a weaker form 686venerable L<Event|Event> module) are not thread-safe (a weaker form
581of thread-safety). This means you must not block within event callbacks, 687of reentrancy). This means you must not block within event callbacks,
582otherwise you might suffer from crashes or worse. The only event library 688otherwise you might suffer from crashes or worse. The only event library
583currently known that is safe to use without C<unblock_sub> is L<EV>. 689currently known that is safe to use without C<unblock_sub> is L<EV>.
584 690
585This function allows your callbacks to block by executing them in another 691This function allows your callbacks to block by executing them in another
586coroutine where it is safe to block. One example where blocking is handy 692coro where it is safe to block. One example where blocking is handy
587is when you use the L<Coro::AIO|Coro::AIO> functions to save results to 693is when you use the L<Coro::AIO|Coro::AIO> functions to save results to
588disk, for example. 694disk, for example.
589 695
590In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when 696In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
591creating event callbacks that want to block. 697creating event callbacks that want to block.
592 698
593If your handler does not plan to block (e.g. simply sends a message to 699If your handler does not plan to block (e.g. simply sends a message to
594another coroutine, or puts some other coroutine into the ready queue), 700another coro, or puts some other coro into the ready queue), there is
595there is no reason to use C<unblock_sub>. 701no reason to use C<unblock_sub>.
596 702
597Note that you also need to use C<unblock_sub> for any other callbacks that 703Note that you also need to use C<unblock_sub> for any other callbacks that
598are indirectly executed by any C-based event loop. For example, when you 704are indirectly executed by any C-based event loop. For example, when you
599use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it 705use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it
600provides callbacks that are the result of some event callback, then you 706provides callbacks that are the result of some event callback, then you
… …
632 } 738 }
633} 739}
634 740
635=item $cb = Coro::rouse_cb 741=item $cb = Coro::rouse_cb
636 742
637Create and return a "rouse callback". That's a code reference that, when 743Create and return a "rouse callback". That's a code reference that,
638called, will save its arguments and notify the owner coroutine of the 744when called, will remember a copy of its arguments and notify the owner
639callback. 745coro of the callback.
640 746
641See the next function. 747See the next function.
642 748
643=item @args = Coro::rouse_wait [$cb] 749=item @args = Coro::rouse_wait [$cb]
644 750
645Wait for the specified rouse callback (or the last one tht was created in 751Wait for the specified rouse callback (or the last one that was created in
646this coroutine). 752this coro).
647 753
648As soon as the callback is invoked (or when the calback was invoked before 754As soon as the callback is invoked (or when the callback was invoked
649C<rouse_wait>), it will return a copy of the arguments originally passed 755before C<rouse_wait>), it will return the arguments originally passed to
650to the rouse callback. 756the rouse callback. In scalar context, that means you get the I<last>
757argument, just as if C<rouse_wait> had a C<return ($a1, $a2, $a3...)>
758statement at the end.
651 759
652See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example. 760See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example.
653 761
654=back 762=back
655 763
… …
657 765
6581; 7661;
659 767
660=head1 HOW TO WAIT FOR A CALLBACK 768=head1 HOW TO WAIT FOR A CALLBACK
661 769
662It is very common for a coroutine to wait for some callback to be 770It is very common for a coro to wait for some callback to be
663called. This occurs naturally when you use coroutines in an otherwise 771called. This occurs naturally when you use coro in an otherwise
664event-based program, or when you use event-based libraries. 772event-based program, or when you use event-based libraries.
665 773
666These typically register a callback for some event, and call that callback 774These typically register a callback for some event, and call that callback
667when the event occured. In a coroutine, however, you typically want to 775when the event occured. In a coro, however, you typically want to
668just wait for the event, simplyifying things. 776just wait for the event, simplyifying things.
669 777
670For example C<< AnyEvent->child >> registers a callback to be called when 778For example C<< AnyEvent->child >> registers a callback to be called when
671a specific child has exited: 779a specific child has exited:
672 780
673 my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... }); 781 my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... });
674 782
675But from withina coroutine, you often just want to write this: 783But from within a coro, you often just want to write this:
676 784
677 my $status = wait_for_child $pid; 785 my $status = wait_for_child $pid;
678 786
679Coro offers two functions specifically designed to make this easy, 787Coro offers two functions specifically designed to make this easy,
680C<Coro::rouse_cb> and C<Coro::rouse_wait>. 788C<Coro::rouse_cb> and C<Coro::rouse_wait>.
681 789
682The first function, C<rouse_cb>, generates and returns a callback that, 790The first function, C<rouse_cb>, generates and returns a callback that,
683when invoked, will save it's arguments and notify the coroutine that 791when invoked, will save its arguments and notify the coro that
684created the callback. 792created the callback.
685 793
686The second function, C<rouse_wait>, waits for the callback to be called 794The second function, C<rouse_wait>, waits for the callback to be called
687(by calling C<schedule> to go to sleep) and returns the arguments 795(by calling C<schedule> to go to sleep) and returns the arguments
688originally passed to the callback. 796originally passed to the callback.
… …
703you can roll your own, using C<schedule>: 811you can roll your own, using C<schedule>:
704 812
705 sub wait_for_child($) { 813 sub wait_for_child($) {
706 my ($pid) = @_; 814 my ($pid) = @_;
707 815
708 # store the current coroutine in $current, 816 # store the current coro in $current,
709 # and provide result variables for the closure passed to ->child 817 # and provide result variables for the closure passed to ->child
710 my $current = $Coro::current; 818 my $current = $Coro::current;
711 my ($done, $rstatus); 819 my ($done, $rstatus);
712 820
713 # pass a closure to ->child 821 # pass a closure to ->child
… …
729 837
730=item fork with pthread backend 838=item fork with pthread backend
731 839
732When Coro is compiled using the pthread backend (which isn't recommended 840When Coro is compiled using the pthread backend (which isn't recommended
733but required on many BSDs as their libcs are completely broken), then 841but required on many BSDs as their libcs are completely broken), then
734coroutines will not survive a fork. There is no known workaround except to 842coro will not survive a fork. There is no known workaround except to
735fix your libc and use a saner backend. 843fix your libc and use a saner backend.
736 844
737=item perl process emulation ("threads") 845=item perl process emulation ("threads")
738 846
739This module is not perl-pseudo-thread-safe. You should only ever use this 847This module is not perl-pseudo-thread-safe. You should only ever use this
740module from the same thread (this requirement might be removed in the 848module from the first thread (this requirement might be removed in the
741future to allow per-thread schedulers, but Coro::State does not yet allow 849future to allow per-thread schedulers, but Coro::State does not yet allow
742this). I recommend disabling thread support and using processes, as having 850this). I recommend disabling thread support and using processes, as having
743the windows process emulation enabled under unix roughly halves perl 851the windows process emulation enabled under unix roughly halves perl
744performance, even when not used. 852performance, even when not used.
745 853
746=item coroutine switching not signal safe 854=item coro switching is not signal safe
747 855
748You must not switch to another coroutine from within a signal handler 856You must not switch to another coro from within a signal handler
749(only relevant with %SIG - most event libraries provide safe signals). 857(only relevant with %SIG - most event libraries provide safe signals).
750 858
751That means you I<MUST NOT> call any function that might "block" the 859That means you I<MUST NOT> call any function that might "block" the
752current coroutine - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or 860current coro - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or
753anything that calls those. Everything else, including calling C<ready>, 861anything that calls those. Everything else, including calling C<ready>,
754works. 862works.
755 863
756=back 864=back
757 865
… …
762 870
763Debugging: L<Coro::Debug>. 871Debugging: L<Coro::Debug>.
764 872
765Support/Utility: L<Coro::Specific>, L<Coro::Util>. 873Support/Utility: L<Coro::Specific>, L<Coro::Util>.
766 874
767Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>. 875Locking and IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>,
876L<Coro::SemaphoreSet>, L<Coro::RWLock>.
768 877
769IO/Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>. 878I/O and Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>.
770 879
771Compatibility: L<Coro::LWP>, L<Coro::BDB>, L<Coro::Storable>, L<Coro::Select>. 880Compatibility with other modules: L<Coro::LWP> (but see also L<AnyEvent::HTTP> for
881a better-working alternative), L<Coro::BDB>, L<Coro::Storable>,
882L<Coro::Select>.
772 883
773XS API: L<Coro::MakeMaker>. 884XS API: L<Coro::MakeMaker>.
774 885
775Low level Configuration, Coroutine Environment: L<Coro::State>. 886Low level Configuration, Thread Environment, Continuations: L<Coro::State>.
776 887
777=head1 AUTHOR 888=head1 AUTHOR
778 889
779 Marc Lehmann <schmorp@schmorp.de> 890 Marc Lehmann <schmorp@schmorp.de>
780 http://home.schmorp.de/ 891 http://home.schmorp.de/

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