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Comparing Coro/Coro.pm (file contents):
Revision 1.6 by root, Tue Jul 10 21:19:47 2001 UTC vs.
Revision 1.83 by root, Fri Nov 24 15:34:33 2006 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
35use strict;
36no warnings "uninitialized";
37
38use Coro::State;
39
40use base qw(Coro::State Exporter);
41
42our $idle; # idle handler
43our $main; # main coroutine
44our $current; # current coroutine
45
46our $VERSION = '2.5';
47
48our @EXPORT = qw(async cede schedule terminate current);
49our %EXPORT_TAGS = (
50 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
51);
52our @EXPORT_OK = @{$EXPORT_TAGS{prio}};
53
54{
55 my @async;
56 my $init;
57
58 # this way of handling attributes simply is NOT scalable ;()
59 sub import {
60 no strict 'refs';
61
62 Coro->export_to_level(1, @_);
63
64 my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE};
65 *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub {
66 my ($package, $ref) = (shift, shift);
67 my @attrs;
68 for (@_) {
69 if ($_ eq "Coro") {
70 push @async, $ref;
71 unless ($init++) {
72 eval q{
73 sub INIT {
74 &async(pop @async) while @async;
75 }
76 };
77 }
78 } else {
79 push @attrs, $_;
80 }
81 }
82 return $old ? $old->($package, $ref, @attrs) : @attrs;
83 };
84 }
85
86}
34 87
35=over 4 88=over 4
36 89
37=cut 90=item $main
38 91
39package Coro; 92This coroutine represents the main program.
40 93
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 94=cut
95
96$main = new Coro;
97
98=item $current (or as function: current)
99
100The current coroutine (the last coroutine switched to). The initial value
101is C<$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.
106
107=cut
108
109# maybe some other module used Coro::Specific before...
110if ($current) {
111 $main->{specific} = $current->{specific};
112}
113
114$current = $main;
115
116sub current() { $current }
117
118=item $idle
119
120A callback that is called whenever the scheduler finds no ready coroutines
121to run. The default implementation prints "FATAL: deadlock detected" and
122exits.
123
124This hook is overwritten by modules such as C<Coro::Timer> and
125C<Coro::Event> to wait on an external event that hopefully wakes up some
126coroutine.
127
128=cut
129
130$idle = sub {
131 print STDERR "FATAL: deadlock detected\n";
132 exit (51);
133};
134
135# this coroutine is necessary because a coroutine
136# cannot destroy itself.
137my @destroy;
138my $manager;
139$manager = new Coro sub {
140 while () {
141 # by overwriting the state object with the manager we destroy it
142 # while still being able to schedule this coroutine (in case it has
143 # been readied multiple times. this is harmless since the manager
144 # can be called as many times as neccessary and will always
145 # remove itself from the runqueue
146 while (@destroy) {
147 my $coro = pop @destroy;
148 $coro->{status} ||= [];
149 $_->ready for @{delete $coro->{join} || []};
150
151 # the next line destroys the coro state, but keeps the
152 # process itself intact (we basically make it a zombie
153 # process that always runs the manager thread, so it's possible
154 # to transfer() to this process).
155 $coro->_clone_state_from ($manager);
156 }
157 &schedule;
158 }
159};
160
161# static methods. not really.
162
163=back
164
165=head2 STATIC METHODS
166
167Static methods are actually functions that operate on the current process only.
168
169=over 4
170
171=item async { ... } [@args...]
172
173Create a new asynchronous process and return it's process object
174(usually unused). When the sub returns the new process is automatically
175terminated.
176
177When the coroutine dies, the program will exit, just as in the main
178program.
179
180 # create a new coroutine that just prints its arguments
181 async {
182 print "@_\n";
183 } 1,2,3,4;
184
185=cut
186
187sub async(&@) {
188 my $pid = new Coro @_;
189 $manager->ready; # this ensures that the stack is cloned from the manager
190 $pid->ready;
191 $pid;
192}
193
194=item schedule
195
196Calls the scheduler. Please note that the current process will not be put
197into the ready queue, so calling this function usually means you will
198never be called again.
199
200=cut
201
202=item cede
203
204"Cede" to other processes. This function puts the current process into the
205ready queue and calls C<schedule>, which has the effect of giving up the
206current "timeslice" to other coroutines of the same or higher priority.
207
208=cut
209
210=item terminate [arg...]
211
212Terminates the current process with the given status values (see L<cancel>).
213
214=cut
215
216sub terminate {
217 $current->cancel (@_);
218}
219
220=back
221
222# dynamic methods
223
224=head2 PROCESS METHODS
225
226These are the methods you can call on process objects.
227
228=over 4
229
230=item new Coro \&sub [, @args...]
231
232Create a new process and return it. When the sub returns the process
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
235by calling the ready method.
236
237=cut
238
239sub _newcoro {
240 terminate &{+shift};
241}
59 242
60sub new { 243sub new {
61 my $class = $_[0]; 244 my $class = shift;
62 my $proc = $_[1] || sub { die "tried to transfer to an empty coroutine" };
63 bless _newprocess {
64 do {
65 eval { &$proc };
66 if ($@) {
67 $error_msg = $@;
68 $error_coro = _newprocess { };
69 &transfer($error_coro, $error);
70 }
71 } while (1);
72 }, $class;
73}
74 245
75=item $prev->transfer($next) 246 $class->SUPER::new (\&_newcoro, @_)
76
77Save the state of the current subroutine in $prev and switch to the
78coroutine saved in $next.
79
80=cut
81
82# I call the _transfer function from a perl function
83# because that way perl saves all important things on
84# the stack.
85sub transfer {
86 _transfer($_[0], $_[1]);
87} 247}
88 248
89=item $error, $error_msg, $error_coro 249=item $process->ready
90 250
91This coroutine will be called on fatal errors. C<$error_msg> and 251Put the given process into the ready queue.
92C<$error_coro> return the error message and the error-causing coroutine
93(NOT an object) respectively. This API might change.
94 252
95=cut 253=cut
96 254
97$error_msg = 255=item $process->cancel (arg...)
98$error_coro = undef;
99 256
100$error = _newprocess { 257Terminates the given process and makes it return the given arguments as
101 print STDERR "FATAL: $error_msg\nprogram aborted\n"; 258status (default: the empty list).
102 exit 50; 259
103}; 260=cut
261
262sub cancel {
263 my $self = shift;
264 $self->{status} = [@_];
265 push @destroy, $self;
266 $manager->ready;
267 &schedule if $current == $self;
268}
269
270=item $process->join
271
272Wait until the coroutine terminates and return any values given to the
273C<terminate> or C<cancel> functions. C<join> can be called multiple times
274from multiple processes.
275
276=cut
277
278sub join {
279 my $self = shift;
280 unless ($self->{status}) {
281 push @{$self->{join}}, $current;
282 &schedule;
283 }
284 wantarray ? @{$self->{status}} : $self->{status}[0];
285}
286
287=item $oldprio = $process->prio ($newprio)
288
289Sets (or gets, if the argument is missing) the priority of the
290process. Higher priority processes get run before lower priority
291processes. Priorities are small signed integers (currently -4 .. +3),
292that you can refer to using PRIO_xxx constants (use the import tag :prio
293to get then):
294
295 PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
296 3 > 1 > 0 > -1 > -3 > -4
297
298 # set priority to HIGH
299 current->prio(PRIO_HIGH);
300
301The idle coroutine ($Coro::idle) always has a lower priority than any
302existing coroutine.
303
304Changing the priority of the current process will take effect immediately,
305but changing the priority of processes in the ready queue (but not
306running) will only take effect after the next schedule (of that
307process). This is a bug that will be fixed in some future version.
308
309=item $newprio = $process->nice ($change)
310
311Similar to C<prio>, but subtract the given value from the priority (i.e.
312higher values mean lower priority, just as in unix).
313
314=item $olddesc = $process->desc ($newdesc)
315
316Sets (or gets in case the argument is missing) the description for this
317process. This is just a free-form string you can associate with a process.
318
319=cut
320
321sub desc {
322 my $old = $_[0]{desc};
323 $_[0]{desc} = $_[1] if @_ > 1;
324 $old;
325}
326
327=back
328
329=cut
104 330
1051; 3311;
106 332
107=back 333=head1 BUGS/LIMITATIONS
108 334
109=head1 BUGS 335 - you must make very sure that no coro is still active on global
336 destruction. very bad things might happen otherwise (usually segfaults).
110 337
111This module has not yet been extensively tested. 338 - this module is not thread-safe. You should only ever use this module
339 from the same thread (this requirement might be losened in the future
340 to allow per-thread schedulers, but Coro::State does not yet allow
341 this).
112 342
113=head1 SEE ALSO 343=head1 SEE ALSO
114 344
115L<Coro::Process>, L<Coro::Signal>. 345Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.
346
347Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
348
349Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.
350
351Embedding: L<Coro:MakeMaker>
116 352
117=head1 AUTHOR 353=head1 AUTHOR
118 354
119 Marc Lehmann <pcg@goof.com> 355 Marc Lehmann <schmorp@schmorp.de>
120 http://www.goof.com/pcg/marc/ 356 http://home.schmorp.de/
121 357
122=cut 358=cut
123 359

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