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Comparing Coro/Coro.pm (file contents):
Revision 1.91 by root, Fri Dec 1 02:17:37 2006 UTC vs.
Revision 1.101 by root, Fri Dec 29 08:36:34 2006 UTC

8 8
9 async { 9 async {
10 # some asynchronous thread of execution 10 # some asynchronous thread of execution
11 }; 11 };
12 12
13 # alternatively create an async process like this: 13 # alternatively create an async coroutine like this:
14 14
15 sub some_func : Coro { 15 sub some_func : Coro {
16 # some more async code 16 # some more async code
17 } 17 }
18 18
19 cede; 19 cede;
20 20
21=head1 DESCRIPTION 21=head1 DESCRIPTION
22 22
23This module collection manages coroutines. Coroutines are similar to 23This module collection manages coroutines. Coroutines are similar
24threads but don't run in parallel. 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
26guarentees you that it will not switch between coroutines unless
27necessary, at easily-identified points in your program, so locking and
28parallel access are rarely an issue, making coroutine programming much
29safer than threads programming.
25 30
31(Perl, however, does not natively support real threads but instead does a
32very slow and memory-intensive emulation of processes using threads. This
33is a performance win on Windows machines, and a loss everywhere else).
34
26In this module, coroutines are defined as "callchain + lexical variables 35In this module, coroutines are defined as "callchain + lexical variables +
27+ @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own 36@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,
28callchain, it's own set of lexicals and it's own set of perl's most 37its own set of lexicals and its own set of perls most important global
29important global variables. 38variables.
30 39
31=cut 40=cut
32 41
33package Coro; 42package Coro;
34 43
41 50
42our $idle; # idle handler 51our $idle; # idle handler
43our $main; # main coroutine 52our $main; # main coroutine
44our $current; # current coroutine 53our $current; # current coroutine
45 54
46our $VERSION = '3.0'; 55our $VERSION = '3.3';
47 56
48our @EXPORT = qw(async cede schedule terminate current); 57our @EXPORT = qw(async cede schedule terminate current unblock_sub);
49our %EXPORT_TAGS = ( 58our %EXPORT_TAGS = (
50 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], 59 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
51); 60);
52our @EXPORT_OK = @{$EXPORT_TAGS{prio}}; 61our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
53 62
54{ 63{
55 my @async; 64 my @async;
56 my $init; 65 my $init;
57 66
58 # this way of handling attributes simply is NOT scalable ;() 67 # this way of handling attributes simply is NOT scalable ;()
59 sub import { 68 sub import {
60 no strict 'refs'; 69 no strict 'refs';
61 70
62 Coro->export_to_level(1, @_); 71 Coro->export_to_level (1, @_);
63 72
64 my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE}; 73 my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
65 *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub { 74 *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
66 my ($package, $ref) = (shift, shift); 75 my ($package, $ref) = (shift, shift);
67 my @attrs; 76 my @attrs;
105C<Coro::current> function instead. 114C<Coro::current> function instead.
106 115
107=cut 116=cut
108 117
109# maybe some other module used Coro::Specific before... 118# maybe some other module used Coro::Specific before...
110if ($current) {
111 $main->{specific} = $current->{specific}; 119$main->{specific} = $current->{specific}
112} 120 if $current;
113 121
114$current = $main; 122_set_current $main;
115 123
116sub current() { $current } 124sub current() { $current }
117 125
118=item $idle 126=item $idle
119 127
129handlers), then it must be prepared to be called recursively. 137handlers), then it must be prepared to be called recursively.
130 138
131=cut 139=cut
132 140
133$idle = sub { 141$idle = sub {
134 print STDERR "FATAL: deadlock detected\n"; 142 require Carp;
135 exit (51); 143 Carp::croak ("FATAL: deadlock detected");
136}; 144};
137 145
138# this coroutine is necessary because a coroutine 146# this coroutine is necessary because a coroutine
139# cannot destroy itself. 147# cannot destroy itself.
140my @destroy; 148my @destroy;
145 # been readied multiple times. this is harmless since the manager 153 # been readied multiple times. this is harmless since the manager
146 # can be called as many times as neccessary and will always 154 # can be called as many times as neccessary and will always
147 # remove itself from the runqueue 155 # remove itself from the runqueue
148 while (@destroy) { 156 while (@destroy) {
149 my $coro = pop @destroy; 157 my $coro = pop @destroy;
158
150 $coro->{status} ||= []; 159 $coro->{status} ||= [];
160
151 $_->ready for @{delete $coro->{join} || []}; 161 $_->ready for @{(delete $coro->{join} ) || []};
162 $_->(@{$coro->{status}}) for @{(delete $coro->{destroy_cb}) || []};
152 163
153 # the next line destroys the coro state, but keeps the 164 # the next line destroys the coro state, but keeps the
154 # process itself intact (we basically make it a zombie 165 # coroutine itself intact (we basically make it a zombie
155 # process that always runs the manager thread, so it's possible 166 # coroutine that always runs the manager thread, so it's possible
156 # to transfer() to this process). 167 # to transfer() to this coroutine).
157 $coro->_clone_state_from ($manager); 168 $coro->_clone_state_from ($manager);
158 } 169 }
159 &schedule; 170 &schedule;
160 } 171 }
161}; 172};
164 175
165=back 176=back
166 177
167=head2 STATIC METHODS 178=head2 STATIC METHODS
168 179
169Static methods are actually functions that operate on the current process only. 180Static methods are actually functions that operate on the current coroutine only.
170 181
171=over 4 182=over 4
172 183
173=item async { ... } [@args...] 184=item async { ... } [@args...]
174 185
175Create a new asynchronous process and return it's process object 186Create a new asynchronous coroutine and return it's coroutine object
176(usually unused). When the sub returns the new process is automatically 187(usually unused). When the sub returns the new coroutine is automatically
177terminated. 188terminated.
178 189
179Calling C<exit> in a coroutine will not work correctly, so do not do that. 190Calling C<exit> in a coroutine will not work correctly, so do not do that.
180 191
181When the coroutine dies, the program will exit, just as in the main 192When the coroutine dies, the program will exit, just as in the main
194 $pid 205 $pid
195} 206}
196 207
197=item schedule 208=item schedule
198 209
199Calls the scheduler. Please note that the current process will not be put 210Calls the scheduler. Please note that the current coroutine will not be put
200into the ready queue, so calling this function usually means you will 211into the ready queue, so calling this function usually means you will
201never be called again unless something else (e.g. an event handler) calls 212never be called again unless something else (e.g. an event handler) calls
202ready. 213ready.
203 214
204The canonical way to wait on external events is this: 215The canonical way to wait on external events is this:
205 216
206 { 217 {
207 # remember current process 218 # remember current coroutine
208 my $current = $Coro::current; 219 my $current = $Coro::current;
209 220
210 # register a hypothetical event handler 221 # register a hypothetical event handler
211 on_event_invoke sub { 222 on_event_invoke sub {
212 # wake up sleeping coroutine 223 # wake up sleeping coroutine
218 # in case we are woken up for other reasons 229 # in case we are woken up for other reasons
219 # (current still defined), loop. 230 # (current still defined), loop.
220 Coro::schedule while $current; 231 Coro::schedule while $current;
221 } 232 }
222 233
223=cut
224
225=item cede 234=item cede
226 235
227"Cede" to other processes. This function puts the current process into the 236"Cede" to other coroutines. This function puts the current coroutine into the
228ready queue and calls C<schedule>, which has the effect of giving up the 237ready queue and calls C<schedule>, which has the effect of giving up the
229current "timeslice" to other coroutines of the same or higher priority. 238current "timeslice" to other coroutines of the same or higher priority.
230 239
231=cut
232
233=item terminate [arg...] 240=item terminate [arg...]
234 241
235Terminates the current process with the given status values (see L<cancel>). 242Terminates the current coroutine with the given status values (see L<cancel>).
236 243
237=cut 244=cut
238 245
239sub terminate { 246sub terminate {
240 $current->cancel (@_); 247 $current->cancel (@_);
242 249
243=back 250=back
244 251
245# dynamic methods 252# dynamic methods
246 253
247=head2 PROCESS METHODS 254=head2 COROUTINE METHODS
248 255
249These are the methods you can call on process objects. 256These are the methods you can call on coroutine objects.
250 257
251=over 4 258=over 4
252 259
253=item new Coro \&sub [, @args...] 260=item new Coro \&sub [, @args...]
254 261
255Create a new process and return it. When the sub returns the process 262Create a new coroutine and return it. When the sub returns the coroutine
256automatically terminates as if C<terminate> with the returned values were 263automatically terminates as if C<terminate> with the returned values were
257called. To make the process run you must first put it into the ready queue 264called. To make the coroutine run you must first put it into the ready queue
258by calling the ready method. 265by calling the ready method.
259 266
260Calling C<exit> in a coroutine will not work correctly, so do not do that. 267Calling C<exit> in a coroutine will not work correctly, so do not do that.
261 268
262=cut 269=cut
263 270
264sub _new_coro { 271sub _run_coro {
265 terminate &{+shift}; 272 terminate &{+shift};
266} 273}
267 274
268sub new { 275sub new {
269 my $class = shift; 276 my $class = shift;
270 277
271 $class->SUPER::new (\&_new_coro, @_) 278 $class->SUPER::new (\&_run_coro, @_)
272} 279}
273 280
274=item $success = $process->ready 281=item $success = $coroutine->ready
275 282
276Put the given process into the ready queue (according to it's priority) 283Put the given coroutine into the ready queue (according to it's priority)
277and return true. If the process is already in the ready queue, do nothing 284and return true. If the coroutine is already in the ready queue, do nothing
278and return false. 285and return false.
279 286
280=item $is_ready = $process->is_ready 287=item $is_ready = $coroutine->is_ready
281 288
282Return wether the process is currently the ready queue or not, 289Return wether the coroutine is currently the ready queue or not,
283 290
284=item $process->cancel (arg...) 291=item $coroutine->cancel (arg...)
285 292
286Terminates the given process and makes it return the given arguments as 293Terminates the given coroutine and makes it return the given arguments as
287status (default: the empty list). 294status (default: the empty list).
288 295
289=cut 296=cut
290 297
291sub cancel { 298sub cancel {
294 push @destroy, $self; 301 push @destroy, $self;
295 $manager->ready; 302 $manager->ready;
296 &schedule if $current == $self; 303 &schedule if $current == $self;
297} 304}
298 305
299=item $process->join 306=item $coroutine->join
300 307
301Wait until the coroutine terminates and return any values given to the 308Wait until the coroutine terminates and return any values given to the
302C<terminate> or C<cancel> functions. C<join> can be called multiple times 309C<terminate> or C<cancel> functions. C<join> can be called multiple times
303from multiple processes. 310from multiple coroutine.
304 311
305=cut 312=cut
306 313
307sub join { 314sub join {
308 my $self = shift; 315 my $self = shift;
311 &schedule; 318 &schedule;
312 } 319 }
313 wantarray ? @{$self->{status}} : $self->{status}[0]; 320 wantarray ? @{$self->{status}} : $self->{status}[0];
314} 321}
315 322
323=item $coroutine->on_destroy (\&cb)
324
325Registers a callback that is called when this coroutine gets destroyed,
326but before it is joined. The callback gets passed the terminate arguments,
327if any.
328
329=cut
330
331sub on_destroy {
332 my ($self, $cb) = @_;
333
334 push @{ $self->{destroy_cb} }, $cb;
335}
336
316=item $oldprio = $process->prio ($newprio) 337=item $oldprio = $coroutine->prio ($newprio)
317 338
318Sets (or gets, if the argument is missing) the priority of the 339Sets (or gets, if the argument is missing) the priority of the
319process. Higher priority processes get run before lower priority 340coroutine. Higher priority coroutines get run before lower priority
320processes. Priorities are small signed integers (currently -4 .. +3), 341coroutines. Priorities are small signed integers (currently -4 .. +3),
321that you can refer to using PRIO_xxx constants (use the import tag :prio 342that you can refer to using PRIO_xxx constants (use the import tag :prio
322to get then): 343to get then):
323 344
324 PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN 345 PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
325 3 > 1 > 0 > -1 > -3 > -4 346 3 > 1 > 0 > -1 > -3 > -4
328 current->prio(PRIO_HIGH); 349 current->prio(PRIO_HIGH);
329 350
330The idle coroutine ($Coro::idle) always has a lower priority than any 351The idle coroutine ($Coro::idle) always has a lower priority than any
331existing coroutine. 352existing coroutine.
332 353
333Changing the priority of the current process will take effect immediately, 354Changing the priority of the current coroutine will take effect immediately,
334but changing the priority of processes in the ready queue (but not 355but changing the priority of coroutines in the ready queue (but not
335running) will only take effect after the next schedule (of that 356running) will only take effect after the next schedule (of that
336process). This is a bug that will be fixed in some future version. 357coroutine). This is a bug that will be fixed in some future version.
337 358
338=item $newprio = $process->nice ($change) 359=item $newprio = $coroutine->nice ($change)
339 360
340Similar to C<prio>, but subtract the given value from the priority (i.e. 361Similar to C<prio>, but subtract the given value from the priority (i.e.
341higher values mean lower priority, just as in unix). 362higher values mean lower priority, just as in unix).
342 363
343=item $olddesc = $process->desc ($newdesc) 364=item $olddesc = $coroutine->desc ($newdesc)
344 365
345Sets (or gets in case the argument is missing) the description for this 366Sets (or gets in case the argument is missing) the description for this
346process. This is just a free-form string you can associate with a process. 367coroutine. This is just a free-form string you can associate with a coroutine.
347 368
348=cut 369=cut
349 370
350sub desc { 371sub desc {
351 my $old = $_[0]{desc}; 372 my $old = $_[0]{desc};
353 $old; 374 $old;
354} 375}
355 376
356=back 377=back
357 378
379=head2 GLOBAL FUNCTIONS
380
381=over 4
382
383=item Coro::nready
384
385Returns the number of coroutines that are currently in the ready state,
386i.e. that can be swicthed to. The value C<0> means that the only runnable
387coroutine is the currently running one, so C<cede> would have no effect,
388and C<schedule> would cause a deadlock unless there is an idle handler
389that wakes up some coroutines.
390
391=item unblock_sub { ... }
392
393This utility function takes a BLOCK or code reference and "unblocks" it,
394returning the new coderef. This means that the new coderef will return
395immediately without blocking, returning nothing, while the original code
396ref will be called (with parameters) from within its own coroutine.
397
398The reason this fucntion exists is that many event libraries (such as the
399venerable L<Event|Event> module) are not coroutine-safe (a weaker form
400of thread-safety). This means you must not block within event callbacks,
401otherwise you might suffer from crashes or worse.
402
403This function allows your callbacks to block by executing them in another
404coroutine where it is safe to block. One example where blocking is handy
405is when you use the L<Coro::AIO|Coro::AIO> functions to save results to
406disk.
407
408In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
409creating event callbacks that want to block.
410
411=cut
412
413our @unblock_pool;
414our @unblock_queue;
415our $UNBLOCK_POOL_SIZE = 2;
416
417sub unblock_handler_ {
418 while () {
419 my ($cb, @arg) = @{ delete $Coro::current->{arg} };
420 $cb->(@arg);
421
422 last if @unblock_pool >= $UNBLOCK_POOL_SIZE;
423 push @unblock_pool, $Coro::current;
424 schedule;
425 }
426}
427
428our $unblock_scheduler = async {
429 while () {
430 while (my $cb = pop @unblock_queue) {
431 my $handler = (pop @unblock_pool or new Coro \&unblock_handler_);
432 $handler->{arg} = $cb;
433 $handler->ready;
434 cede;
435 }
436
437 schedule;
438 }
439};
440
441sub unblock_sub(&) {
442 my $cb = shift;
443
444 sub {
445 push @unblock_queue, [$cb, @_];
446 $unblock_scheduler->ready;
447 }
448}
449
450=back
451
358=cut 452=cut
359 453
3601; 4541;
361 455
362=head1 BUGS/LIMITATIONS 456=head1 BUGS/LIMITATIONS

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