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Revision 1.6 by root, Tue Jul 10 21:19:47 2001 UTC vs.
Revision 1.53 by root, Tue May 27 01:15:26 2003 UTC

1=head1 NAME 1=head1 NAME
2 2
3Coro - create and manage simple 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 $new->transfer($main);
12 print "in coroutine again, switching back\n";
13 $new->transfer($main);
14 }; 11 };
15 12
16 $main = new Coro; 13 # alternatively create an async process like this:
17 14
18 print "in main, switching to coroutine\n"; 15 sub some_func : Coro {
19 $main->transfer($new); 16 # some more async code
20 print "back in main, switch to coroutine again\n"; 17 }
21 $main->transfer($new); 18
22 print "back in main\n"; 19 cede;
23 20
24=head1 DESCRIPTION 21=head1 DESCRIPTION
25 22
26This module implements coroutines. Coroutines, similar to continuations, 23This module collection manages coroutines. Coroutines are similar to
27allow you to run more than one "thread of execution" in parallel. Unlike 24threads but don't run in parallel.
28threads this, only voluntary switching is used so locking problems are
29greatly reduced.
30 25
31Although this is the "main" module of the Coro family it provides only 26In this module, coroutines are defined as "callchain + lexical variables
32low-level functionality. See L<Coro::Process> and related modules for a 27+ @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own
33more useful process abstraction including scheduling. 28callchain, it's own set of lexicals and it's own set of perl's most
29important global variables.
30
31=cut
32
33package Coro;
34
35no warnings qw(uninitialized);
36
37use Coro::State;
38
39use base Exporter;
40
41$VERSION = 0.7;
42
43@EXPORT = qw(async cede schedule terminate 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}};
48
49{
50 my @async;
51 my $init;
52
53 # this way of handling attributes simply is NOT scalable ;()
54 sub import {
55 Coro->export_to_level(1, @_);
56 my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
57 *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
58 my ($package, $ref) = (shift, shift);
59 my @attrs;
60 for (@_) {
61 if ($_ eq "Coro") {
62 push @async, $ref;
63 unless ($init++) {
64 eval q{
65 sub INIT {
66 &async(pop @async) while @async;
67 }
68 };
69 }
70 } else {
71 push @attrs, $_;
72 }
73 }
74 return $old ? $old->($package, $ref, @attrs) : @attrs;
75 };
76 }
77
78}
34 79
35=over 4 80=over 4
36 81
37=cut 82=item $main
38 83
39package Coro; 84This coroutine represents the main program.
40 85
41BEGIN {
42 $VERSION = 0.03;
43
44 require XSLoader;
45 XSLoader::load Coro, $VERSION;
46}
47
48=item $coro = new [$coderef [, @args]]
49
50Create a new coroutine and return it. The first C<transfer> call to this
51coroutine will start execution at the given coderef. If, the subroutine
52returns it will be executed again.
53
54If the coderef is omitted this function will create a new "empty"
55coroutine, i.e. a coroutine that cannot be transfered to but can be used
56to save the current coroutine in.
57
58=cut 86=cut
87
88our $main = new Coro;
89
90=item $current (or as function: current)
91
92The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).
93
94=cut
95
96# maybe some other module used Coro::Specific before...
97if ($current) {
98 $main->{specific} = $current->{specific};
99}
100
101our $current = $main;
102
103sub current() { $current }
104
105=item $idle
106
107The coroutine to switch to when no other coroutine is running. The default
108implementation prints "FATAL: deadlock detected" and exits.
109
110=cut
111
112# should be done using priorities :(
113our $idle = new Coro sub {
114 print STDERR "FATAL: deadlock detected\n";
115 exit(51);
116};
117
118# this coroutine is necessary because a coroutine
119# cannot destroy itself.
120my @destroy;
121my $manager;
122$manager = new Coro sub {
123 while() {
124 # by overwriting the state object with the manager we destroy it
125 # while still being able to schedule this coroutine (in case it has
126 # been readied multiple times. this is harmless since the manager
127 # can be called as many times as neccessary and will always
128 # remove itself from the runqueue
129 while (@destroy) {
130 my $coro = pop @destroy;
131 $coro->{status} ||= [];
132 $_->ready for @{delete $coro->{join} || []};
133 $coro->{_coro_state} = $manager->{_coro_state};
134 }
135 &schedule;
136 }
137};
138
139# static methods. not really.
140
141=back
142
143=head2 STATIC METHODS
144
145Static methods are actually functions that operate on the current process only.
146
147=over 4
148
149=item async { ... } [@args...]
150
151Create a new asynchronous process and return it's process object
152(usually unused). When the sub returns the new process is automatically
153terminated.
154
155 # create a new coroutine that just prints its arguments
156 async {
157 print "@_\n";
158 } 1,2,3,4;
159
160The coderef you submit MUST NOT be a closure that refers to variables
161in an outer scope. This does NOT work. Pass arguments into it instead.
162
163=cut
164
165sub async(&@) {
166 my $pid = new Coro @_;
167 $manager->ready; # this ensures that the stack is cloned from the manager
168 $pid->ready;
169 $pid;
170}
171
172=item schedule
173
174Calls the scheduler. Please note that the current process will not be put
175into the ready queue, so calling this function usually means you will
176never be called again.
177
178=cut
179
180=item cede
181
182"Cede" to other processes. This function puts the current process into the
183ready queue and calls C<schedule>, which has the effect of giving up the
184current "timeslice" to other coroutines of the same or higher priority.
185
186=cut
187
188=item terminate [arg...]
189
190Terminates the current process.
191
192Future versions of this function will allow result arguments.
193
194=cut
195
196sub terminate {
197 $current->{status} = [@_];
198 $current->cancel;
199 &schedule;
200 die; # NORETURN
201}
202
203=back
204
205# dynamic methods
206
207=head2 PROCESS METHODS
208
209These are the methods you can call on process objects.
210
211=over 4
212
213=item new Coro \&sub [, @args...]
214
215Create a new process and return it. When the sub returns the process
216automatically terminates as if C<terminate> with the returned values were
217called. To make the process run you must first put it into the ready queue
218by calling the ready method.
219
220=cut
221
222sub _newcoro {
223 terminate &{+shift};
224}
59 225
60sub new { 226sub new {
61 my $class = $_[0]; 227 my $class = shift;
62 my $proc = $_[1] || sub { die "tried to transfer to an empty coroutine" }; 228 bless {
63 bless _newprocess { 229 _coro_state => (new Coro::State $_[0] && \&_newcoro, @_),
64 do {
65 eval { &$proc };
66 if ($@) {
67 $error_msg = $@;
68 $error_coro = _newprocess { };
69 &transfer($error_coro, $error);
70 }
71 } while (1);
72 }, $class; 230 }, $class;
73} 231}
74 232
75=item $prev->transfer($next) 233=item $process->ready
76 234
77Save the state of the current subroutine in $prev and switch to the 235Put the given process into the ready queue.
78coroutine saved in $next.
79 236
80=cut 237=cut
81 238
82# I call the _transfer function from a perl function 239=item $process->cancel
83# because that way perl saves all important things on
84# the stack.
85sub transfer {
86 _transfer($_[0], $_[1]);
87}
88 240
89=item $error, $error_msg, $error_coro 241Like C<terminate>, but terminates the specified process instead.
90 242
91This coroutine will be called on fatal errors. C<$error_msg> and
92C<$error_coro> return the error message and the error-causing coroutine
93(NOT an object) respectively. This API might change.
94
95=cut 243=cut
96 244
97$error_msg = 245sub cancel {
98$error_coro = undef; 246 push @destroy, $_[0];
247 $manager->ready;
248 &schedule if $current == $_[0];
249}
99 250
100$error = _newprocess { 251=item $process->join
101 print STDERR "FATAL: $error_msg\nprogram aborted\n"; 252
102 exit 50; 253Wait until the coroutine terminates and return any values given to the
103}; 254C<terminate> function. C<join> can be called multiple times from multiple
255processes.
256
257=cut
258
259sub join {
260 my $self = shift;
261 unless ($self->{status}) {
262 push @{$self->{join}}, $current;
263 &schedule;
264 }
265 wantarray ? @{$self->{status}} : $self->{status}[0];
266}
267
268=item $oldprio = $process->prio($newprio)
269
270Sets (or gets, if the argument is missing) the priority of the
271process. Higher priority processes get run before lower priority
272processes. Priorities are small signed integers (currently -4 .. +3),
273that you can refer to using PRIO_xxx constants (use the import tag :prio
274to get then):
275
276 PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
277 3 > 1 > 0 > -1 > -3 > -4
278
279 # set priority to HIGH
280 current->prio(PRIO_HIGH);
281
282The idle coroutine ($Coro::idle) always has a lower priority than any
283existing coroutine.
284
285Changing the priority of the current process will take effect immediately,
286but changing the priority of processes in the ready queue (but not
287running) will only take effect after the next schedule (of that
288process). This is a bug that will be fixed in some future version.
289
290=cut
291
292sub prio {
293 my $old = $_[0]{prio};
294 $_[0]{prio} = $_[1] if @_ > 1;
295 $old;
296}
297
298=item $newprio = $process->nice($change)
299
300Similar to C<prio>, but subtract the given value from the priority (i.e.
301higher values mean lower priority, just as in unix).
302
303=cut
304
305sub nice {
306 $_[0]{prio} -= $_[1];
307}
308
309=item $olddesc = $process->desc($newdesc)
310
311Sets (or gets in case the argument is missing) the description for this
312process. This is just a free-form string you can associate with a process.
313
314=cut
315
316sub desc {
317 my $old = $_[0]{desc};
318 $_[0]{desc} = $_[1] if @_ > 1;
319 $old;
320}
321
322=back
323
324=cut
104 325
1051; 3261;
106 327
107=back 328=head1 BUGS/LIMITATIONS
108 329
109=head1 BUGS 330 - you must make very sure that no coro is still active on global
331 destruction. very bad things might happen otherwise (usually segfaults).
110 332
111This module has not yet been extensively tested. 333 - this module is not thread-safe. You should only ever use this module
334 from the same thread (this requirement might be losened in the future
335 to allow per-thread schedulers, but Coro::State does not yet allow
336 this).
112 337
113=head1 SEE ALSO 338=head1 SEE ALSO
114 339
115L<Coro::Process>, L<Coro::Signal>. 340L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>,
341L<Coro::Signal>, L<Coro::State>, L<Coro::Event>, L<Coro::RWLock>,
342L<Coro::Handle>, L<Coro::Socket>.
116 343
117=head1 AUTHOR 344=head1 AUTHOR
118 345
119 Marc Lehmann <pcg@goof.com> 346 Marc Lehmann <pcg@goof.com>
120 http://www.goof.com/pcg/marc/ 347 http://www.goof.com/pcg/marc/

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