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Revision 1.6 by root, Tue Jul 10 21:19:47 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 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+ @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own
33more useful process abstraction including scheduling. 28callchain, it's own set of lexicals and it's own set of perl's most
29important global variables.
30
31=cut
32
33package Coro;
34
35BEGIN { eval { require warnings } && warnings->unimport ("uninitialized") }
36
37use Coro::State;
38
39use vars qw($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}
34 81
35=over 4 82=over 4
36 83
37=cut 84=item $main
38 85
39package Coro; 86This coroutine represents the main program.
40 87
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 88=cut
89
90$main = new Coro;
91
92=item $current (or as function: current)
93
94The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course).
95
96=cut
97
98# maybe some other module used Coro::Specific before...
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);
118};
119
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} || []};
135
136 # the next line destroys the _coro_state, but keeps the
137 # process itself intact (we basically make it a zombie
138 # process that always runs the manager thread, so it's possible
139 # to transfer() to this process).
140 $coro->{_coro_state} = $manager->{_coro_state};
141 }
142 &schedule;
143 }
144};
145
146# static methods. not really.
147
148=back
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
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}
59 224
60sub new { 225sub new {
61 my $class = $_[0]; 226 my $class = shift;
62 my $proc = $_[1] || sub { die "tried to transfer to an empty coroutine" }; 227 bless {
63 bless _newprocess { 228 _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; 229 }, $class;
73} 230}
74 231
75=item $prev->transfer($next) 232=item $process->ready
76 233
77Save the state of the current subroutine in $prev and switch to the 234Put the given process into the ready queue.
78coroutine saved in $next.
79 235
80=cut 236=cut
81 237
82# I call the _transfer function from a perl function 238=item $process->cancel (arg...)
83# because that way perl saves all important things on
84# the stack.
85sub transfer {
86 _transfer($_[0], $_[1]);
87}
88 239
89=item $error, $error_msg, $error_coro 240Temrinates the given process and makes it return the given arguments as
241status (default: the empty list).
90 242
91This coroutine will be called on fatal errors. C<$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 my $self = shift;
247 $self->{status} = [@_];
248 push @destroy, $self;
249 $manager->ready;
250 &schedule if $current == $self;
251}
99 252
100$error = _newprocess { 253=item $process->join
101 print STDERR "FATAL: $error_msg\nprogram aborted\n"; 254
102 exit 50; 255Wait until the coroutine terminates and return any values given to the
103}; 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
104 327
1051; 3281;
106 329
107=back 330=head1 BUGS/LIMITATIONS
108 331
109=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).
110 334
111This 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).
112 339
113=head1 SEE ALSO 340=head1 SEE ALSO
114 341
115L<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>.
116 345
117=head1 AUTHOR 346=head1 AUTHOR
118 347
119 Marc Lehmann <pcg@goof.com> 348 Marc Lehmann <pcg@goof.com>
120 http://www.goof.com/pcg/marc/ 349 http://home.schmorp.de/
121 350
122=cut 351=cut
123 352

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