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Revision 1.105 by root, Fri Jan 5 16:55:01 2007 UTC vs.
Revision 1.129 by root, Wed Sep 19 22:33:08 2007 UTC

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20 20
21=head1 DESCRIPTION 21=head1 DESCRIPTION
22 22
23This module collection manages coroutines. Coroutines are similar 23This module collection manages coroutines. Coroutines are similar
24to threads but don't run in parallel at the same time even on SMP 24to threads but don't run in parallel at the same time even on SMP
25machines. The specific flavor of coroutine use din this module also 25machines. The specific flavor of coroutine used in this module also
26guarentees you that it will not switch between coroutines unless 26guarantees you that it will not switch between coroutines unless
27necessary, at easily-identified points in your program, so locking and 27necessary, at easily-identified points in your program, so locking and
28parallel access are rarely an issue, making coroutine programming much 28parallel access are rarely an issue, making coroutine programming much
29safer than threads programming. 29safer than threads programming.
30 30
31(Perl, however, does not natively support real threads but instead does a 31(Perl, however, does not natively support real threads but instead does a
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50 50
51our $idle; # idle handler 51our $idle; # idle handler
52our $main; # main coroutine 52our $main; # main coroutine
53our $current; # current coroutine 53our $current; # current coroutine
54 54
55our $VERSION = '3.3'; 55our $VERSION = '3.7';
56 56
57our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); 57our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
58our %EXPORT_TAGS = ( 58our %EXPORT_TAGS = (
59 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], 59 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
60); 60);
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108 108
109The current coroutine (the last coroutine switched to). The initial value 109The current coroutine (the last coroutine switched to). The initial value
110is C<$main> (of course). 110is C<$main> (of course).
111 111
112This variable is B<strictly> I<read-only>. It is provided for performance 112This variable is B<strictly> I<read-only>. It is provided for performance
113reasons. If performance is not essentiel you are encouraged to use the 113reasons. If performance is not essential you are encouraged to use the
114C<Coro::current> function instead. 114C<Coro::current> function instead.
115 115
116=cut 116=cut
117 117
118# maybe some other module used Coro::Specific before... 118# maybe some other module used Coro::Specific before...
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159# cannot destroy itself. 159# cannot destroy itself.
160my @destroy; 160my @destroy;
161my $manager; 161my $manager;
162 162
163$manager = new Coro sub { 163$manager = new Coro sub {
164 $current->desc ("[coro manager]");
165
164 while () { 166 while () {
165 (shift @destroy)->_cancel 167 (shift @destroy)->_cancel
166 while @destroy; 168 while @destroy;
167 169
168 &schedule; 170 &schedule;
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185 187
186Create a new asynchronous coroutine and return it's coroutine object 188Create a new asynchronous coroutine and return it's coroutine object
187(usually unused). When the sub returns the new coroutine is automatically 189(usually unused). When the sub returns the new coroutine is automatically
188terminated. 190terminated.
189 191
190Calling C<exit> in a coroutine will not work correctly, so do not do that. 192Calling C<exit> in a coroutine will do the same as calling exit outside
191 193the coroutine. Likewise, when the coroutine dies, the program will exit,
192When the coroutine dies, the program will exit, just as in the main 194just as it would in the main program.
193program.
194 195
195 # create a new coroutine that just prints its arguments 196 # create a new coroutine that just prints its arguments
196 async { 197 async {
197 print "@_\n"; 198 print "@_\n";
198 } 1,2,3,4; 199 } 1,2,3,4;
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210Similar to C<async>, but uses a coroutine pool, so you should not call 211Similar to C<async>, but uses a coroutine pool, so you should not call
211terminate or join (although you are allowed to), and you get a coroutine 212terminate or join (although you are allowed to), and you get a coroutine
212that might have executed other code already (which can be good or bad :). 213that might have executed other code already (which can be good or bad :).
213 214
214Also, the block is executed in an C<eval> context and a warning will be 215Also, the block is executed in an C<eval> context and a warning will be
215issued in case of an exception instead of terminating the program, as C<async> does. 216issued in case of an exception instead of terminating the program, as
217C<async> does. As the coroutine is being reused, stuff like C<on_destroy>
218will not work in the expected way, unless you call terminate or cancel,
219which somehow defeats the purpose of pooling.
216 220
217The priority will be reset to C<0> after each job, otherwise the coroutine 221The priority will be reset to C<0> after each job, otherwise the coroutine
218will be re-used "as-is". 222will be re-used "as-is".
219 223
220The pool size is limited to 8 idle coroutines (this can be adjusted by 224The pool size is limited to 8 idle coroutines (this can be adjusted by
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230our $POOL_SIZE = 8; 234our $POOL_SIZE = 8;
231our @pool; 235our @pool;
232 236
233sub pool_handler { 237sub pool_handler {
234 while () { 238 while () {
235 my ($cb, @arg) = @{ delete $current->{_invoke} }; 239 $current->{desc} = "[async_pool]";
236 240
237 eval { 241 eval {
242 my ($cb, @arg) = @{ delete $current->{_invoke} or return };
238 $cb->(@arg); 243 $cb->(@arg);
239 }; 244 };
240 warn $@ if $@; 245 warn $@ if $@;
241 246
242 last if @pool >= $POOL_SIZE; 247 last if @pool >= $POOL_SIZE;
248
243 push @pool, $current; 249 push @pool, $current;
244 250 $current->{desc} = "[async_pool idle]";
251 $current->save (Coro::State::SAVE_DEF);
245 $current->prio (0); 252 $current->prio (0);
246 schedule; 253 schedule;
247 } 254 }
248} 255}
249 256
250sub async_pool(&@) { 257sub async_pool(&@) {
251 # this is also inlined into the unlock_scheduler 258 # this is also inlined into the unlock_scheduler
252 my $coro = (pop @pool or new Coro \&pool_handler); 259 my $coro = (pop @pool) || new Coro \&pool_handler;;
253 260
254 $coro->{_invoke} = [@_]; 261 $coro->{_invoke} = [@_];
255 $coro->ready; 262 $coro->ready;
256 263
257 $coro 264 $coro
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275 # wake up sleeping coroutine 282 # wake up sleeping coroutine
276 $current->ready; 283 $current->ready;
277 undef $current; 284 undef $current;
278 }; 285 };
279 286
280 # call schedule until event occured. 287 # call schedule until event occurred.
281 # in case we are woken up for other reasons 288 # in case we are woken up for other reasons
282 # (current still defined), loop. 289 # (current still defined), loop.
283 Coro::schedule while $current; 290 Coro::schedule while $current;
284 } 291 }
285 292
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287 294
288"Cede" to other coroutines. This function puts the current coroutine into the 295"Cede" to other coroutines. This function puts the current coroutine into the
289ready queue and calls C<schedule>, which has the effect of giving up the 296ready queue and calls C<schedule>, which has the effect of giving up the
290current "timeslice" to other coroutines of the same or higher priority. 297current "timeslice" to other coroutines of the same or higher priority.
291 298
299Returns true if at least one coroutine switch has happened.
300
292=item Coro::cede_notself 301=item Coro::cede_notself
293 302
294Works like cede, but is not exported by default and will cede to any 303Works like cede, but is not exported by default and will cede to any
295coroutine, regardless of priority, once. 304coroutine, regardless of priority, once.
305
306Returns true if at least one coroutine switch has happened.
296 307
297=item terminate [arg...] 308=item terminate [arg...]
298 309
299Terminates the current coroutine with the given status values (see L<cancel>). 310Terminates the current coroutine with the given status values (see L<cancel>).
300 311
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319Create a new coroutine and return it. When the sub returns the coroutine 330Create a new coroutine and return it. When the sub returns the coroutine
320automatically terminates as if C<terminate> with the returned values were 331automatically terminates as if C<terminate> with the returned values were
321called. To make the coroutine run you must first put it into the ready queue 332called. To make the coroutine run you must first put it into the ready queue
322by calling the ready method. 333by calling the ready method.
323 334
324Calling C<exit> in a coroutine will not work correctly, so do not do that. 335See C<async> for additional discussion.
325 336
326=cut 337=cut
327 338
328sub _run_coro { 339sub _run_coro {
329 terminate &{+shift}; 340 terminate &{+shift};
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452=over 4 463=over 4
453 464
454=item Coro::nready 465=item Coro::nready
455 466
456Returns the number of coroutines that are currently in the ready state, 467Returns the number of coroutines that are currently in the ready state,
457i.e. that can be swicthed to. The value C<0> means that the only runnable 468i.e. that can be switched to. The value C<0> means that the only runnable
458coroutine is the currently running one, so C<cede> would have no effect, 469coroutine is the currently running one, so C<cede> would have no effect,
459and C<schedule> would cause a deadlock unless there is an idle handler 470and C<schedule> would cause a deadlock unless there is an idle handler
460that wakes up some coroutines. 471that wakes up some coroutines.
461 472
462=item my $guard = Coro::guard { ... } 473=item my $guard = Coro::guard { ... }
463 474
464This creates and returns a guard object. Nothing happens until the objetc 475This creates and returns a guard object. Nothing happens until the object
465gets destroyed, in which case the codeblock given as argument will be 476gets destroyed, in which case the codeblock given as argument will be
466executed. This is useful to free locks or other resources in case of a 477executed. This is useful to free locks or other resources in case of a
467runtime error or when the coroutine gets canceled, as in both cases the 478runtime error or when the coroutine gets canceled, as in both cases the
468guard block will be executed. The guard object supports only one method, 479guard block will be executed. The guard object supports only one method,
469C<< ->cancel >>, which will keep the codeblock from being executed. 480C<< ->cancel >>, which will keep the codeblock from being executed.
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498This utility function takes a BLOCK or code reference and "unblocks" it, 509This utility function takes a BLOCK or code reference and "unblocks" it,
499returning the new coderef. This means that the new coderef will return 510returning the new coderef. This means that the new coderef will return
500immediately without blocking, returning nothing, while the original code 511immediately without blocking, returning nothing, while the original code
501ref will be called (with parameters) from within its own coroutine. 512ref will be called (with parameters) from within its own coroutine.
502 513
503The reason this fucntion exists is that many event libraries (such as the 514The reason this function exists is that many event libraries (such as the
504venerable L<Event|Event> module) are not coroutine-safe (a weaker form 515venerable L<Event|Event> module) are not coroutine-safe (a weaker form
505of thread-safety). This means you must not block within event callbacks, 516of thread-safety). This means you must not block within event callbacks,
506otherwise you might suffer from crashes or worse. 517otherwise you might suffer from crashes or worse.
507 518
508This function allows your callbacks to block by executing them in another 519This function allows your callbacks to block by executing them in another
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520# we create a special coro because we want to cede, 531# we create a special coro because we want to cede,
521# to reduce pressure on the coro pool (because most callbacks 532# to reduce pressure on the coro pool (because most callbacks
522# return immediately and can be reused) and because we cannot cede 533# return immediately and can be reused) and because we cannot cede
523# inside an event callback. 534# inside an event callback.
524our $unblock_scheduler = async { 535our $unblock_scheduler = async {
536 $current->desc ("[unblock_sub scheduler]");
525 while () { 537 while () {
526 while (my $cb = pop @unblock_queue) { 538 while (my $cb = pop @unblock_queue) {
527 # this is an inlined copy of async_pool 539 # this is an inlined copy of async_pool
528 my $coro = (pop @pool or new Coro \&pool_handler); 540 my $coro = (pop @pool or new Coro \&pool_handler);
529 541
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554 566
555 - you must make very sure that no coro is still active on global 567 - you must make very sure that no coro is still active on global
556 destruction. very bad things might happen otherwise (usually segfaults). 568 destruction. very bad things might happen otherwise (usually segfaults).
557 569
558 - this module is not thread-safe. You should only ever use this module 570 - this module is not thread-safe. You should only ever use this module
559 from the same thread (this requirement might be losened in the future 571 from the same thread (this requirement might be loosened in the future
560 to allow per-thread schedulers, but Coro::State does not yet allow 572 to allow per-thread schedulers, but Coro::State does not yet allow
561 this). 573 this).
562 574
563=head1 SEE ALSO 575=head1 SEE ALSO
564 576

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