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Revision 1.6 by root, Tue Jul 10 21:19:47 2001 UTC vs.
Revision 1.79 by root, Fri Nov 3 00:56:02 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 Exporter::;
41
42our $idle; # idle coroutine
43our $main; # main coroutine
44our $current; # current coroutine
45
46our $VERSION = '2.1';
47
48our @EXPORT = qw(async cede schedule terminate current);
49our %EXPORT_TAGS = (
50 prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
51);
52our @EXPORT_OK = @{$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 $current (or as function: current)
99
100The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).
101
102=cut
103
104# maybe some other module used Coro::Specific before...
105if ($current) {
106 $main->{specific} = $current->{specific};
107}
108
109$current = $main;
110
111sub current() { $current }
112
113=item $idle
114
115The coroutine to switch to when no other coroutine is running. The default
116implementation prints "FATAL: deadlock detected" and exits.
117
118=cut
119
120# should be done using priorities :(
121$idle = new Coro sub {
122 print STDERR "FATAL: deadlock detected\n";
123 exit(51);
124};
125
126# this coroutine is necessary because a coroutine
127# cannot destroy itself.
128my @destroy;
129my $manager;
130$manager = new Coro sub {
131 while () {
132 # by overwriting the state object with the manager we destroy it
133 # while still being able to schedule this coroutine (in case it has
134 # been readied multiple times. this is harmless since the manager
135 # can be called as many times as neccessary and will always
136 # remove itself from the runqueue
137 while (@destroy) {
138 my $coro = pop @destroy;
139 $coro->{status} ||= [];
140 $_->ready for @{delete $coro->{join} || []};
141
142 # the next line destroys the _coro_state, but keeps the
143 # process itself intact (we basically make it a zombie
144 # process that always runs the manager thread, so it's possible
145 # to transfer() to this process).
146 $coro->{_coro_state} = $manager->{_coro_state};
147 }
148 &schedule;
149 }
150};
151
152# static methods. not really.
153
154=back
155
156=head2 STATIC METHODS
157
158Static methods are actually functions that operate on the current process only.
159
160=over 4
161
162=item async { ... } [@args...]
163
164Create a new asynchronous process and return it's process object
165(usually unused). When the sub returns the new process is automatically
166terminated.
167
168When the coroutine dies, the program will exit, just as in the main
169program.
170
171 # create a new coroutine that just prints its arguments
172 async {
173 print "@_\n";
174 } 1,2,3,4;
175
176=cut
177
178sub async(&@) {
179 my $pid = new Coro @_;
180 $manager->ready; # this ensures that the stack is cloned from the manager
181 $pid->ready;
182 $pid;
183}
184
185=item schedule
186
187Calls the scheduler. Please note that the current process will not be put
188into the ready queue, so calling this function usually means you will
189never be called again.
190
191=cut
192
193=item cede
194
195"Cede" to other processes. This function puts the current process into the
196ready queue and calls C<schedule>, which has the effect of giving up the
197current "timeslice" to other coroutines of the same or higher priority.
198
199=cut
200
201=item terminate [arg...]
202
203Terminates the current process with the given status values (see L<cancel>).
204
205=cut
206
207sub terminate {
208 $current->cancel (@_);
209}
210
211=back
212
213# dynamic methods
214
215=head2 PROCESS METHODS
216
217These are the methods you can call on process objects.
218
219=over 4
220
221=item new Coro \&sub [, @args...]
222
223Create a new process and return it. When the sub returns the process
224automatically terminates as if C<terminate> with the returned values were
225called. To make the process run you must first put it into the ready queue
226by calling the ready method.
227
228=cut
229
230sub _newcoro {
231 terminate &{+shift};
232}
59 233
60sub new { 234sub new {
61 my $class = $_[0]; 235 my $class = shift;
62 my $proc = $_[1] || sub { die "tried to transfer to an empty coroutine" }; 236 bless {
63 bless _newprocess { 237 _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; 238 }, $class;
73} 239}
74 240
75=item $prev->transfer($next) 241=item $process->ready
76 242
77Save the state of the current subroutine in $prev and switch to the 243Put the given process into the ready queue.
78coroutine saved in $next.
79 244
80=cut 245=cut
81 246
82# I call the _transfer function from a perl function 247=item $process->cancel (arg...)
83# because that way perl saves all important things on
84# the stack.
85sub transfer {
86 _transfer($_[0], $_[1]);
87}
88 248
89=item $error, $error_msg, $error_coro 249Terminates the given process and makes it return the given arguments as
250status (default: the empty list).
90 251
91This coroutine will be called on fatal errors. C<$error_msg> and
92C<$error_coro> return the error message and the error-causing coroutine
93(NOT an object) respectively. This API might change.
94
95=cut 252=cut
96 253
97$error_msg = 254sub cancel {
98$error_coro = undef; 255 my $self = shift;
256 $self->{status} = [@_];
257 push @destroy, $self;
258 $manager->ready;
259 &schedule if $current == $self;
260}
99 261
100$error = _newprocess { 262=item $process->join
101 print STDERR "FATAL: $error_msg\nprogram aborted\n"; 263
102 exit 50; 264Wait until the coroutine terminates and return any values given to the
103}; 265C<terminate> or C<cancel> functions. C<join> can be called multiple times
266from multiple processes.
267
268=cut
269
270sub join {
271 my $self = shift;
272 unless ($self->{status}) {
273 push @{$self->{join}}, $current;
274 &schedule;
275 }
276 wantarray ? @{$self->{status}} : $self->{status}[0];
277}
278
279=item $oldprio = $process->prio($newprio)
280
281Sets (or gets, if the argument is missing) the priority of the
282process. Higher priority processes get run before lower priority
283processes. Priorities are small signed integers (currently -4 .. +3),
284that you can refer to using PRIO_xxx constants (use the import tag :prio
285to get then):
286
287 PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
288 3 > 1 > 0 > -1 > -3 > -4
289
290 # set priority to HIGH
291 current->prio(PRIO_HIGH);
292
293The idle coroutine ($Coro::idle) always has a lower priority than any
294existing coroutine.
295
296Changing the priority of the current process will take effect immediately,
297but changing the priority of processes in the ready queue (but not
298running) will only take effect after the next schedule (of that
299process). This is a bug that will be fixed in some future version.
300
301=cut
302
303sub prio {
304 my $old = $_[0]{prio};
305 $_[0]{prio} = $_[1] if @_ > 1;
306 $old;
307}
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=cut
315
316sub nice {
317 $_[0]{prio} -= $_[1];
318}
319
320=item $olddesc = $process->desc($newdesc)
321
322Sets (or gets in case the argument is missing) the description for this
323process. This is just a free-form string you can associate with a process.
324
325=cut
326
327sub desc {
328 my $old = $_[0]{desc};
329 $_[0]{desc} = $_[1] if @_ > 1;
330 $old;
331}
332
333=back
334
335=cut
104 336
1051; 3371;
106 338
107=back 339=head1 BUGS/LIMITATIONS
108 340
109=head1 BUGS 341 - you must make very sure that no coro is still active on global
342 destruction. very bad things might happen otherwise (usually segfaults).
110 343
111This module has not yet been extensively tested. 344 - this module is not thread-safe. You should only ever use this module
345 from the same thread (this requirement might be losened in the future
346 to allow per-thread schedulers, but Coro::State does not yet allow
347 this).
112 348
113=head1 SEE ALSO 349=head1 SEE ALSO
114 350
115L<Coro::Process>, L<Coro::Signal>. 351Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>.
352
353Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.
354
355Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>.
356
357Embedding: L<Coro:MakeMaker>
116 358
117=head1 AUTHOR 359=head1 AUTHOR
118 360
119 Marc Lehmann <pcg@goof.com> 361 Marc Lehmann <schmorp@schmorp.de>
120 http://www.goof.com/pcg/marc/ 362 http://home.schmorp.de/
121 363
122=cut 364=cut
123 365

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