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Revision 1.22 by root, Mon Jul 23 02:14:19 2001 UTC vs.
Revision 1.42 by root, Tue Nov 6 20:37:20 2001 UTC

… …
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 to
24Threads but don't run in parallel. 24threads but don't run in parallel.
25
26This module is still experimental, see the BUGS section below.
27 25
28In this module, coroutines are defined as "callchain + lexical variables 26In this module, coroutines are defined as "callchain + lexical variables
29+ @_ + $_ + $@ + $^W), that is, a coroutine has it's own callchain, it's 27+ @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own
30own set of lexicals and it's own set of perl's most important global 28callchain, it's own set of lexicals and it's own set of perl's most
31variables. 29important global variables.
32
33WARNING: When using this module, make sure that, at program end, no
34coroutines are still running OR just call exit before falling off the
35end. The reason for this is that some coroutine of yours might have called
36into a C function, and falling off the end of main:: results in returning
37to that C function instead if to the main C interpreter.
38
39WARNING: Unless you really know what you are doing, do NOT do context
40switches inside callbacks from the XS level. The reason for this is
41similar to the reason above: A callback calls a perl function, this
42perl function does a context switch, some other callback is called, the
43original function returns from it - to what? To the wrong XS function,
44with totally different return values. Unfortunately, this includes
45callbacks done by perl itself (tie'd variables!).
46
47The only workaround for this is to do coroutines on C level.
48 30
49=cut 31=cut
50 32
51package Coro; 33package Coro;
52 34
35no warnings qw(uninitialized);
36
53use Coro::State; 37use Coro::State;
54 38
55use base Exporter; 39use base Exporter;
56 40
57$VERSION = 0.10; 41$VERSION = 0.52;
58 42
59@EXPORT = qw(async cede schedule terminate current); 43@EXPORT = qw(async cede schedule terminate current);
60@EXPORT_OK = qw($current); 44%EXPORT_TAGS = (
45 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
46);
47@EXPORT_OK = @{$EXPORT_TAGS{prio}};
61 48
62{ 49{
63 my @async; 50 my @async;
51 my $init;
64 52
65 # this way of handling attributes simply is NOT scalable ;() 53 # this way of handling attributes simply is NOT scalable ;()
66 sub import { 54 sub import {
67 Coro->export_to_level(1, @_); 55 Coro->export_to_level(1, @_);
68 my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE}; 56 my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
… …
70 my ($package, $ref) = (shift, shift); 58 my ($package, $ref) = (shift, shift);
71 my @attrs; 59 my @attrs;
72 for (@_) { 60 for (@_) {
73 if ($_ eq "Coro") { 61 if ($_ eq "Coro") {
74 push @async, $ref; 62 push @async, $ref;
63 unless ($init++) {
64 eval q{
65 sub INIT {
66 &async(pop @async) while @async;
67 }
68 };
69 }
75 } else { 70 } else {
76 push @attrs, $_; 71 push @attrs, $_;
77 } 72 }
78 } 73 }
79 return $old ? $old->($package, $ref, @attrs) : @attrs; 74 return $old ? $old->($package, $ref, @attrs) : @attrs;
80 }; 75 };
81 } 76 }
82 77
83 sub INIT {
84 &async(pop @async) while @async;
85 }
86} 78}
87 79
88=item $main 80=item $main
89 81
90This coroutine represents the main program. 82This coroutine represents the main program.
… …
119our $idle = new Coro sub { 111our $idle = new Coro sub {
120 print STDERR "FATAL: deadlock detected\n"; 112 print STDERR "FATAL: deadlock detected\n";
121 exit(51); 113 exit(51);
122}; 114};
123 115
124# we really need priorities... 116# this coroutine is necessary because a coroutine
125my @ready; # the ready queue. hehe, rather broken ;) 117# cannot destroy itself.
118my @destroy;
119my $manager;
120$manager = new Coro sub {
121 while() {
122 # by overwriting the state object with the manager we destroy it
123 # while still being able to schedule this coroutine (in case it has
124 # been readied multiple times. this is harmless since the manager
125 # can be called as many times as neccessary and will always
126 # remove itself from the runqueue
127 while (@destroy) {
128 my $coro = pop @destroy;
129 $coro->{status} ||= [];
130 $_->ready for @{delete $coro->{join} || []};
131 $coro->{_coro_state} = $manager->{_coro_state};
132 }
133 &schedule;
134 }
135};
126 136
127# static methods. not really. 137# static methods. not really.
128 138
129=head2 STATIC METHODS 139=head2 STATIC METHODS
130 140
… …
148 158
149=cut 159=cut
150 160
151sub async(&@) { 161sub async(&@) {
152 my $pid = new Coro @_; 162 my $pid = new Coro @_;
163 $manager->ready; # this ensures that the stack is cloned from the manager
153 $pid->ready; 164 $pid->ready;
154 $pid; 165 $pid;
155} 166}
156 167
157=item schedule 168=item schedule
… …
160into the ready queue, so calling this function usually means you will 171into the ready queue, so calling this function usually means you will
161never be called again. 172never be called again.
162 173
163=cut 174=cut
164 175
165my $prev;
166
167sub schedule {
168 # should be done using priorities :(
169 ($prev, $current) = ($current, shift @ready || $idle);
170 Coro::State::transfer($prev, $current);
171}
172
173=item cede 176=item cede
174 177
175"Cede" to other processes. This function puts the current process into the 178"Cede" to other processes. This function puts the current process into the
176ready queue and calls C<schedule>, which has the effect of giving up the 179ready queue and calls C<schedule>, which has the effect of giving up the
177current "timeslice" to other coroutines of the same or higher priority. 180current "timeslice" to other coroutines of the same or higher priority.
178 181
179=cut 182=cut
180 183
181sub cede { 184=item terminate [arg...]
185
186Terminates the current process.
187
188Future versions of this function will allow result arguments.
189
190=cut
191
192sub terminate {
193 $current->{status} = [@_];
182 $current->ready; 194 $current->cancel;
183 &schedule; 195 &schedule;
184} 196 die; # NORETURN
185
186=item terminate
187
188Terminates the current process.
189
190Future versions of this function will allow result arguments.
191
192=cut
193
194sub terminate {
195 my $self = $current;
196 $self->{_results} = [@_];
197 $current = shift @ready || $idle;
198 Coro::State::transfer(delete $self->{_coro_state}, $current);
199 # cannot return
200 die;
201} 197}
202 198
203=back 199=back
204 200
205# dynamic methods 201# dynamic methods
… …
211=over 4 207=over 4
212 208
213=item new Coro \&sub [, @args...] 209=item new Coro \&sub [, @args...]
214 210
215Create a new process and return it. When the sub returns the process 211Create a new process and return it. When the sub returns the process
216automatically terminates. To start the process you must first put it into 212automatically terminates as if C<terminate> with the returned values were
213called. To make the process run you must first put it into the ready queue
217the ready queue by calling the ready method. 214by calling the ready method.
218
219The coderef you submit MUST NOT be a closure that refers to variables
220in an outer scope. This does NOT work. Pass arguments into it instead.
221 215
222=cut 216=cut
223 217
224sub _newcoro { 218sub _newcoro {
225 terminate &{+shift}; 219 terminate &{+shift};
… …
232 }, $class; 226 }, $class;
233} 227}
234 228
235=item $process->ready 229=item $process->ready
236 230
237Put the current process into the ready queue. 231Put the given process into the ready queue.
238 232
239=cut 233=cut
240 234
241sub ready { 235=item $process->cancel
236
237Like C<terminate>, but terminates the specified process instead.
238
239=cut
240
241sub cancel {
242 push @ready, $_[0]; 242 push @destroy, $_[0];
243 $manager->ready;
244 &schedule if $current == $_[0];
245}
246
247=item $process->join
248
249Wait until the coroutine terminates and return any values given to the
250C<terminate> function. C<join> can be called multiple times from multiple
251processes.
252
253=cut
254
255sub join {
256 my $self = shift;
257 unless ($self->{status}) {
258 push @{$self->{join}}, $current;
259 &schedule;
260 }
261 wantarray ? @{$self->{status}} : $self->{status}[0];
262}
263
264=item $oldprio = $process->prio($newprio)
265
266Sets (or gets, if the argument is missing) the priority of the
267process. Higher priority processes get run before lower priority
268processes. Priorities are smalled signed integer (currently -4 .. +3),
269that you can refer to using PRIO_xxx constants (use the import tag :prio
270to get then):
271
272 PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
273 3 > 1 > 0 > -1 > -3 > -4
274
275 # set priority to HIGH
276 current->prio(PRIO_HIGH);
277
278The idle coroutine ($Coro::idle) always has a lower priority than any
279existing coroutine.
280
281Changing the priority of the current process will take effect immediately,
282but changing the priority of processes in the ready queue (but not
283running) will only take effect after the next schedule (of that
284process). This is a bug that will be fixed in some future version.
285
286=cut
287
288sub prio {
289 my $old = $_[0]{prio};
290 $_[0]{prio} = $_[1] if @_ > 1;
291 $old;
292}
293
294=item $newprio = $process->nice($change)
295
296Similar to C<prio>, but subtract the given value from the priority (i.e.
297higher values mean lower priority, just as in unix).
298
299=cut
300
301sub nice {
302 $_[0]{prio} -= $_[1];
303}
304
305=item $olddesc = $process->desc($newdesc)
306
307Sets (or gets in case the argument is missing) the description for this
308process. This is just a free-form string you can associate with a process.
309
310=cut
311
312sub desc {
313 my $old = $_[0]{desc};
314 $_[0]{desc} = $_[1] if @_ > 1;
315 $old;
243} 316}
244 317
245=back 318=back
246 319
247=cut 320=cut
248 321
2491; 3221;
250 323
251=head1 BUGS/LIMITATIONS 324=head1 BUGS/LIMITATIONS
252 325
253 - could be faster, especially when the core would introduce special 326 - you must make very sure that no coro is still active on global destruction.
254 support for coroutines (like it does for threads). 327 very bad things might happen otherwise (usually segfaults).
255 - there is still a memleak on coroutine termination that I could not
256 identify. Could be as small as a single SV.
257 - this module is not well-tested.
258 - if variables or arguments "disappear" (become undef) or become
259 corrupted please contact the author so he cen iron out the
260 remaining bugs.
261 - this module is not thread-safe. You must only ever use this module from 328 - this module is not thread-safe. You should only ever use this module from
262 the same thread (this requirement might be loosened in the future to 329 the same thread (this requirement might be loosened in the future to
263 allow per-thread schedulers, but Coro::State does not yet allow this). 330 allow per-thread schedulers, but Coro::State does not yet allow this).
264 331
265=head1 SEE ALSO 332=head1 SEE ALSO
266 333
267L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>, 334L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,
268L<Coro::Signal>, L<Coro::State>, L<Coro::Event>. 335L<Coro::Signal>, L<Coro::State>, L<Coro::Event>, L<Coro::RWLock>,
336L<Coro::Handle>, L<Coro::Socket>.
269 337
270=head1 AUTHOR 338=head1 AUTHOR
271 339
272 Marc Lehmann <pcg@goof.com> 340 Marc Lehmann <pcg@goof.com>
273 http://www.goof.com/pcg/marc/ 341 http://www.goof.com/pcg/marc/

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