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Revision 1.30 by root, Sat Aug 11 19:59:19 2001 UTC vs.
Revision 1.89 by root, Mon Nov 27 02:01:33 2006 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 + C stack), that is, a coroutine has it's own 27+ @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own
30callchain, it's own set of lexicals and it's own set of perl's most 28callchain, it's own set of lexicals and it's own set of perl's most
31important global variables. 29important global variables.
32 30
33=cut 31=cut
34 32
35package Coro; 33package Coro;
36 34
35use strict;
36no warnings "uninitialized";
37
37use Coro::State; 38use Coro::State;
38 39
39use base Exporter; 40use base qw(Coro::State Exporter);
40 41
41$VERSION = 0.45; 42our $idle; # idle handler
43our $main; # main coroutine
44our $current; # current coroutine
42 45
46our $VERSION = '3.0';
47
43@EXPORT = qw(async cede schedule terminate current); 48our @EXPORT = qw(async cede schedule terminate current);
44@EXPORT_OK = qw($current); 49our %EXPORT_TAGS = (
50 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
51);
52our @EXPORT_OK = @{$EXPORT_TAGS{prio}};
45 53
46{ 54{
47 my @async; 55 my @async;
48 my $init; 56 my $init;
49 57
50 # this way of handling attributes simply is NOT scalable ;() 58 # this way of handling attributes simply is NOT scalable ;()
51 sub import { 59 sub import {
60 no strict 'refs';
61
52 Coro->export_to_level(1, @_); 62 Coro->export_to_level(1, @_);
63
53 my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE}; 64 my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
54 *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub { 65 *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
55 my ($package, $ref) = (shift, shift); 66 my ($package, $ref) = (shift, shift);
56 my @attrs; 67 my @attrs;
57 for (@_) { 68 for (@_) {
… …
72 }; 83 };
73 } 84 }
74 85
75} 86}
76 87
88=over 4
89
77=item $main 90=item $main
78 91
79This coroutine represents the main program. 92This coroutine represents the main program.
80 93
81=cut 94=cut
82 95
83our $main = new Coro; 96$main = new Coro;
84 97
85=item $current (or as function: current) 98=item $current (or as function: current)
86 99
87The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course). 100The current coroutine (the last coroutine switched to). The initial value
101is C<$main> (of course).
102
103This variable is B<strictly> I<read-only>. It is provided for performance
104reasons. If performance is not essentiel you are encouraged to use the
105C<Coro::current> function instead.
88 106
89=cut 107=cut
90 108
91# maybe some other module used Coro::Specific before... 109# maybe some other module used Coro::Specific before...
92if ($current) { 110if ($current) {
93 $main->{specific} = $current->{specific}; 111 $main->{specific} = $current->{specific};
94} 112}
95 113
96our $current = $main; 114$current = $main;
97 115
98sub current() { $current } 116sub current() { $current }
99 117
100=item $idle 118=item $idle
101 119
102The coroutine to switch to when no other coroutine is running. The default 120A callback that is called whenever the scheduler finds no ready coroutines
103implementation prints "FATAL: deadlock detected" and exits. 121to run. The default implementation prints "FATAL: deadlock detected" and
122exits.
104 123
105=cut 124This hook is overwritten by modules such as C<Coro::Timer> and
125C<Coro::Event> to wait on an external event that hopefully wakes up some
126coroutine.
106 127
107# should be done using priorities :( 128=cut
108our $idle = new Coro sub { 129
130$idle = sub {
109 print STDERR "FATAL: deadlock detected\n"; 131 print STDERR "FATAL: deadlock detected\n";
110 exit(51); 132 exit (51);
111}; 133};
112 134
113# this coroutine is necessary because a coroutine 135# this coroutine is necessary because a coroutine
114# cannot destroy itself. 136# cannot destroy itself.
115my @destroy; 137my @destroy;
116my $manager = new Coro sub { 138my $manager; $manager = new Coro sub {
117 while() { 139 while () {
118 delete ((pop @destroy)->{_coro_state}) while @destroy; 140 # by overwriting the state object with the manager we destroy it
141 # while still being able to schedule this coroutine (in case it has
142 # been readied multiple times. this is harmless since the manager
143 # can be called as many times as neccessary and will always
144 # remove itself from the runqueue
145 while (@destroy) {
146 my $coro = pop @destroy;
147 $coro->{status} ||= [];
148 $_->ready for @{delete $coro->{join} || []};
149
150 # the next line destroys the coro state, but keeps the
151 # process itself intact (we basically make it a zombie
152 # process that always runs the manager thread, so it's possible
153 # to transfer() to this process).
154 $coro->_clone_state_from ($manager);
155 }
119 &schedule; 156 &schedule;
120 } 157 }
121}; 158};
122 159
123# static methods. not really. 160# static methods. not really.
124 161
162=back
163
125=head2 STATIC METHODS 164=head2 STATIC METHODS
126 165
127Static methods are actually functions that operate on the current process only. 166Static methods are actually functions that operate on the current process only.
128 167
129=over 4 168=over 4
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131=item async { ... } [@args...] 170=item async { ... } [@args...]
132 171
133Create a new asynchronous process and return it's process object 172Create a new asynchronous process and return it's process object
134(usually unused). When the sub returns the new process is automatically 173(usually unused). When the sub returns the new process is automatically
135terminated. 174terminated.
175
176Calling C<exit> in a coroutine will not work correctly, so do not do that.
177
178When the coroutine dies, the program will exit, just as in the main
179program.
136 180
137 # create a new coroutine that just prints its arguments 181 # create a new coroutine that just prints its arguments
138 async { 182 async {
139 print "@_\n"; 183 print "@_\n";
140 } 1,2,3,4; 184 } 1,2,3,4;
141 185
142The coderef you submit MUST NOT be a closure that refers to variables
143in an outer scope. This does NOT work. Pass arguments into it instead.
144
145=cut 186=cut
146 187
147sub async(&@) { 188sub async(&@) {
148 my $pid = new Coro @_; 189 my $pid = new Coro @_;
149 $manager->ready; # this ensures that the stack is cloned from the manager
150 $pid->ready; 190 $pid->ready;
151 $pid; 191 $pid
152} 192}
153 193
154=item schedule 194=item schedule
155 195
156Calls the scheduler. Please note that the current process will not be put 196Calls the scheduler. Please note that the current process will not be put
… …
165ready queue and calls C<schedule>, which has the effect of giving up the 205ready queue and calls C<schedule>, which has the effect of giving up the
166current "timeslice" to other coroutines of the same or higher priority. 206current "timeslice" to other coroutines of the same or higher priority.
167 207
168=cut 208=cut
169 209
170=item terminate 210=item terminate [arg...]
171 211
172Terminates the current process. 212Terminates the current process with the given status values (see L<cancel>).
173
174Future versions of this function will allow result arguments.
175 213
176=cut 214=cut
177 215
178sub terminate { 216sub terminate {
179 $current->cancel; 217 $current->cancel (@_);
180 &schedule;
181 die; # NORETURN
182} 218}
183 219
184=back 220=back
185 221
186# dynamic methods 222# dynamic methods
… …
192=over 4 228=over 4
193 229
194=item new Coro \&sub [, @args...] 230=item new Coro \&sub [, @args...]
195 231
196Create a new process and return it. When the sub returns the process 232Create a new process and return it. When the sub returns the process
197automatically terminates. To start the process you must first put it into 233automatically terminates as if C<terminate> with the returned values were
234called. To make the process run you must first put it into the ready queue
198the ready queue by calling the ready method. 235by calling the ready method.
199 236
200The coderef you submit MUST NOT be a closure that refers to variables 237Calling C<exit> in a coroutine will not work correctly, so do not do that.
201in an outer scope. This does NOT work. Pass arguments into it instead.
202 238
203=cut 239=cut
204 240
205sub _newcoro { 241sub _new_coro {
206 terminate &{+shift}; 242 terminate &{+shift};
207} 243}
208 244
209sub new { 245sub new {
210 my $class = shift; 246 my $class = shift;
211 bless { 247
212 _coro_state => (new Coro::State $_[0] && \&_newcoro, @_), 248 $class->SUPER::new (\&_new_coro, @_)
213 }, $class;
214} 249}
215 250
216=item $process->ready 251=item $process->ready
217 252
218Put the current process into the ready queue. 253Put the given process into the ready queue.
219 254
220=cut 255=cut
221 256
222=item $process->cancel 257=item $process->cancel (arg...)
223 258
224Like C<terminate>, but terminates the specified process instead. 259Terminates the given process and makes it return the given arguments as
260status (default: the empty list).
225 261
226=cut 262=cut
227 263
228sub cancel { 264sub cancel {
265 my $self = shift;
266 $self->{status} = [@_];
229 push @destroy, $_[0]; 267 push @destroy, $self;
230 $manager->ready; 268 $manager->ready;
269 &schedule if $current == $self;
270}
271
272=item $process->join
273
274Wait until the coroutine terminates and return any values given to the
275C<terminate> or C<cancel> functions. C<join> can be called multiple times
276from multiple processes.
277
278=cut
279
280sub join {
281 my $self = shift;
282 unless ($self->{status}) {
283 push @{$self->{join}}, $current;
284 &schedule;
285 }
286 wantarray ? @{$self->{status}} : $self->{status}[0];
287}
288
289=item $oldprio = $process->prio ($newprio)
290
291Sets (or gets, if the argument is missing) the priority of the
292process. Higher priority processes get run before lower priority
293processes. Priorities are small signed integers (currently -4 .. +3),
294that you can refer to using PRIO_xxx constants (use the import tag :prio
295to get then):
296
297 PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
298 3 > 1 > 0 > -1 > -3 > -4
299
300 # set priority to HIGH
301 current->prio(PRIO_HIGH);
302
303The idle coroutine ($Coro::idle) always has a lower priority than any
304existing coroutine.
305
306Changing the priority of the current process will take effect immediately,
307but changing the priority of processes in the ready queue (but not
308running) will only take effect after the next schedule (of that
309process). This is a bug that will be fixed in some future version.
310
311=item $newprio = $process->nice ($change)
312
313Similar to C<prio>, but subtract the given value from the priority (i.e.
314higher values mean lower priority, just as in unix).
315
316=item $olddesc = $process->desc ($newdesc)
317
318Sets (or gets in case the argument is missing) the description for this
319process. This is just a free-form string you can associate with a process.
320
321=cut
322
323sub desc {
324 my $old = $_[0]{desc};
325 $_[0]{desc} = $_[1] if @_ > 1;
326 $old;
231} 327}
232 328
233=back 329=back
234 330
235=cut 331=cut
236 332
2371; 3331;
238 334
239=head1 BUGS/LIMITATIONS 335=head1 BUGS/LIMITATIONS
240 336
241 - could be faster, especially when the core would introduce special 337 - you must make very sure that no coro is still active on global
242 support for coroutines (like it does for threads). 338 destruction. very bad things might happen otherwise (usually segfaults).
243 - there is still a memleak on coroutine termination that I could not 339
244 identify. Could be as small as a single SV.
245 - this module is not well-tested.
246 - if variables or arguments "disappear" (become undef) or become
247 corrupted please contact the author so he cen iron out the
248 remaining bugs.
249 - this module is not thread-safe. You must only ever use this module from 340 - this module is not thread-safe. You should only ever use this module
250 the same thread (this requirement might be loosened in the future to 341 from the same thread (this requirement might be losened in the future
251 allow per-thread schedulers, but Coro::State does not yet allow this). 342 to allow per-thread schedulers, but Coro::State does not yet allow
343 this).
252 344
253=head1 SEE ALSO 345=head1 SEE ALSO
254 346
255L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>, 347Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.
256L<Coro::Signal>, L<Coro::State>, L<Coro::Event>, L<Coro::RWLock>, 348
257L<Coro::Handle>, L<Coro::Socket>. 349Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
350
351Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.
352
353Embedding: L<Coro:MakeMaker>
258 354
259=head1 AUTHOR 355=head1 AUTHOR
260 356
261 Marc Lehmann <pcg@goof.com> 357 Marc Lehmann <schmorp@schmorp.de>
262 http://www.goof.com/pcg/marc/ 358 http://home.schmorp.de/
263 359
264=cut 360=cut
265 361

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