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Revision 1.3 by root, Tue Jul 3 04:02:31 2001 UTC vs.
Revision 1.65 by root, Tue Feb 22 19:51:58 2005 UTC

1=head1 NAME 1=head1 NAME
2 2
3Coro - create and manage coroutines 3Coro - coroutine process abstraction
4 4
5=head1 SYNOPSIS 5=head1 SYNOPSIS
6 6
7 use Coro; 7 use Coro;
8 8
9 $new = new Coro sub { 9 async {
10 print "in coroutine, switching back\n"; 10 # some asynchronous thread of execution
11 $Coro::main->resume;
12 print "in coroutine again, switching back\n";
13 $Coro::main->resume;
14 }; 11 };
15 12
16 print "in main, switching to coroutine\n"; 13 # alternatively create an async process like this:
17 $new->resume; 14
18 print "back in main, switch to coroutine again\n"; 15 sub some_func : Coro {
19 $new->resume; 16 # some more async code
20 print "back in main\n"; 17 }
18
19 cede;
21 20
22=head1 DESCRIPTION 21=head1 DESCRIPTION
23 22
24This module implements coroutines. Coroutines, similar to continuations, 23This module collection manages coroutines. Coroutines are similar to
25allow you to run more than one "thread of execution" in parallel. Unlike 24threads but don't run in parallel.
26threads this, only voluntary switching is used so locking problems are
27greatly reduced.
28 25
29Although this is the "main" module of the Coro family it provides only 26In this module, coroutines are defined as "callchain + lexical variables
30low-level functionality. See L<Coro::Process> and related modules for a 27+ @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own
31more useful process abstraction including scheduling. 28callchain, it's own set of lexicals and it's own set of perl's most
29important global variables.
30
31=cut
32
33package Coro;
34
35BEGIN { eval { require warnings } && warnings->unimport ("uninitialized") }
36
37use Coro::State;
38
39use vars qw($idle $main $current);
40
41use base Exporter;
42
43$VERSION = 1.1;
44
45@EXPORT = qw(async cede schedule terminate current);
46%EXPORT_TAGS = (
47 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
48);
49@EXPORT_OK = @{$EXPORT_TAGS{prio}};
50
51{
52 my @async;
53 my $init;
54
55 # this way of handling attributes simply is NOT scalable ;()
56 sub import {
57 Coro->export_to_level(1, @_);
58 my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
59 *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
60 my ($package, $ref) = (shift, shift);
61 my @attrs;
62 for (@_) {
63 if ($_ eq "Coro") {
64 push @async, $ref;
65 unless ($init++) {
66 eval q{
67 sub INIT {
68 &async(pop @async) while @async;
69 }
70 };
71 }
72 } else {
73 push @attrs, $_;
74 }
75 }
76 return $old ? $old->($package, $ref, @attrs) : @attrs;
77 };
78 }
79
80}
32 81
33=over 4 82=over 4
34 83
35=cut
36
37package Coro;
38
39BEGIN {
40 $VERSION = 0.01;
41
42 require XSLoader;
43 XSLoader::load Coro, $VERSION;
44}
45
46=item $main 84=item $main
47 85
48This coroutine represents the main program. 86This coroutine represents the main program.
49 87
50=item $current 88=cut
89
90$main = new Coro;
91
92=item $current (or as function: current)
51 93
52The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course). 94The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).
53 95
54=cut 96=cut
55 97
56$main = $current = _newprocess { 98# maybe some other module used Coro::Specific before...
57 # never being called 99if ($current) {
100 $main->{specific} = $current->{specific};
101}
102
103$current = $main;
104
105sub current() { $current }
106
107=item $idle
108
109The coroutine to switch to when no other coroutine is running. The default
110implementation prints "FATAL: deadlock detected" and exits.
111
112=cut
113
114# should be done using priorities :(
115$idle = new Coro sub {
116 print STDERR "FATAL: deadlock detected\n";
117 exit(51);
58}; 118};
59 119
60=item $error, $error_msg, $error_coro 120# this coroutine is necessary because a coroutine
121# cannot destroy itself.
122my @destroy;
123my $manager;
124$manager = new Coro sub {
125 while () {
126 # by overwriting the state object with the manager we destroy it
127 # while still being able to schedule this coroutine (in case it has
128 # been readied multiple times. this is harmless since the manager
129 # can be called as many times as neccessary and will always
130 # remove itself from the runqueue
131 while (@destroy) {
132 my $coro = pop @destroy;
133 $coro->{status} ||= [];
134 $_->ready for @{delete $coro->{join} || []};
61 135
62This coroutine will be called on fatal errors. C<$error_msg> and 136 # the next line destroys the _coro_state, but keeps the
63C<$error_coro> return the error message and the error-causing coroutine, 137 # process itself intact (we basically make it a zombie
64respectively. 138 # process that always runs the manager thread, so it's possible
65 139 # to transfer() to this process).
66=cut 140 $coro->{_coro_state} = $manager->{_coro_state};
67 141 }
68$error_msg = 142 &schedule;
69$error_coro = undef; 143 }
70
71$error = _newprocess {
72 print STDERR "FATAL: $error_msg\nprogram aborted\n";
73 exit 250;
74}; 144};
75 145
76=item $coro = new $coderef [, @args] 146# static methods. not really.
77 147
78Create a new coroutine and return it. The first C<resume> call to this 148=back
79coroutine will start execution at the given coderef. If it returns it
80should return a coroutine to switch to. If, after returning, the coroutine
81is C<resume>d again it starts execution again at the givne coderef.
82 149
150=head2 STATIC METHODS
151
152Static methods are actually functions that operate on the current process only.
153
154=over 4
155
156=item async { ... } [@args...]
157
158Create a new asynchronous process and return it's process object
159(usually unused). When the sub returns the new process is automatically
160terminated.
161
162 # create a new coroutine that just prints its arguments
163 async {
164 print "@_\n";
165 } 1,2,3,4;
166
83=cut 167=cut
168
169sub async(&@) {
170 my $pid = new Coro @_;
171 $manager->ready; # this ensures that the stack is cloned from the manager
172 $pid->ready;
173 $pid;
174}
175
176=item schedule
177
178Calls the scheduler. Please note that the current process will not be put
179into the ready queue, so calling this function usually means you will
180never be called again.
181
182=cut
183
184=item cede
185
186"Cede" to other processes. This function puts the current process into the
187ready queue and calls C<schedule>, which has the effect of giving up the
188current "timeslice" to other coroutines of the same or higher priority.
189
190=cut
191
192=item terminate [arg...]
193
194Terminates the current process with the given status values (see L<cancel>).
195
196=cut
197
198sub terminate {
199 $current->cancel (@_);
200}
201
202=back
203
204# dynamic methods
205
206=head2 PROCESS METHODS
207
208These are the methods you can call on process objects.
209
210=over 4
211
212=item new Coro \&sub [, @args...]
213
214Create a new process and return it. When the sub returns the process
215automatically terminates as if C<terminate> with the returned values were
216called. To make the process run you must first put it into the ready queue
217by calling the ready method.
218
219=cut
220
221sub _newcoro {
222 terminate &{+shift};
223}
84 224
85sub new { 225sub new {
86 my $class = $_[0]; 226 my $class = shift;
87 my $proc = $_[1]; 227 bless {
88 bless _newprocess { 228 _coro_state => (new Coro::State $_[0] && \&_newcoro, @_),
89 do {
90 eval { &$proc->resume };
91 if ($@) {
92 ($error_msg, $error_coro) = ($@, $current);
93 $error->resume;
94 }
95 } while ();
96 }, $class; 229 }, $class;
97} 230}
98 231
99=item $coro->resume 232=item $process->ready
100 233
101Resume execution at the given coroutine. 234Put the given process into the ready queue.
102 235
103=cut 236=cut
104 237
105my $prev; 238=item $process->cancel (arg...)
106 239
107sub resume { 240Temrinates the given process and makes it return the given arguments as
108 $prev = $current; $current = $_[0]; 241status (default: the empty list).
109 _transfer($prev, $current); 242
243=cut
244
245sub cancel {
246 my $self = shift;
247 $self->{status} = [@_];
248 push @destroy, $self;
249 $manager->ready;
250 &schedule if $current == $self;
110} 251}
252
253=item $process->join
254
255Wait until the coroutine terminates and return any values given to the
256C<terminate> or C<cancel> functions. C<join> can be called multiple times
257from multiple processes.
258
259=cut
260
261sub join {
262 my $self = shift;
263 unless ($self->{status}) {
264 push @{$self->{join}}, $current;
265 &schedule;
266 }
267 wantarray ? @{$self->{status}} : $self->{status}[0];
268}
269
270=item $oldprio = $process->prio($newprio)
271
272Sets (or gets, if the argument is missing) the priority of the
273process. Higher priority processes get run before lower priority
274processes. Priorities are small signed integers (currently -4 .. +3),
275that you can refer to using PRIO_xxx constants (use the import tag :prio
276to get then):
277
278 PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
279 3 > 1 > 0 > -1 > -3 > -4
280
281 # set priority to HIGH
282 current->prio(PRIO_HIGH);
283
284The idle coroutine ($Coro::idle) always has a lower priority than any
285existing coroutine.
286
287Changing the priority of the current process will take effect immediately,
288but changing the priority of processes in the ready queue (but not
289running) will only take effect after the next schedule (of that
290process). This is a bug that will be fixed in some future version.
291
292=cut
293
294sub prio {
295 my $old = $_[0]{prio};
296 $_[0]{prio} = $_[1] if @_ > 1;
297 $old;
298}
299
300=item $newprio = $process->nice($change)
301
302Similar to C<prio>, but subtract the given value from the priority (i.e.
303higher values mean lower priority, just as in unix).
304
305=cut
306
307sub nice {
308 $_[0]{prio} -= $_[1];
309}
310
311=item $olddesc = $process->desc($newdesc)
312
313Sets (or gets in case the argument is missing) the description for this
314process. This is just a free-form string you can associate with a process.
315
316=cut
317
318sub desc {
319 my $old = $_[0]{desc};
320 $_[0]{desc} = $_[1] if @_ > 1;
321 $old;
322}
323
324=back
325
326=cut
111 327
1121; 3281;
113 329
114=back 330=head1 BUGS/LIMITATIONS
115 331
116=head1 BUGS 332 - you must make very sure that no coro is still active on global
333 destruction. very bad things might happen otherwise (usually segfaults).
117 334
118This module has not yet been extensively tested. 335 - this module is not thread-safe. You should only ever use this module
336 from the same thread (this requirement might be losened in the future
337 to allow per-thread schedulers, but Coro::State does not yet allow
338 this).
119 339
120=head1 SEE ALSO 340=head1 SEE ALSO
121 341
122L<Coro::Process>, L<Coro::Signal>. 342L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,
343L<Coro::Signal>, L<Coro::State>, L<Coro::Timer>, L<Coro::Event>,
344L<Coro::Handle>, L<Coro::RWLock>, L<Coro::Socket>.
123 345
124=head1 AUTHOR 346=head1 AUTHOR
125 347
126 Marc Lehmann <pcg@goof.com> 348 Marc Lehmann <pcg@goof.com>
127 http://www.goof.com/pcg/marc/ 349 http://home.schmorp.de/
128 350
129=cut 351=cut
130 352

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