1 |
=head1 NAME |
2 |
|
3 |
Coro - coroutine process abstraction |
4 |
|
5 |
=head1 SYNOPSIS |
6 |
|
7 |
use Coro; |
8 |
|
9 |
async { |
10 |
# some asynchronous thread of execution |
11 |
}; |
12 |
|
13 |
# alternatively create an async process like this: |
14 |
|
15 |
sub some_func : Coro { |
16 |
# some more async code |
17 |
} |
18 |
|
19 |
cede; |
20 |
|
21 |
=head1 DESCRIPTION |
22 |
|
23 |
This module collection manages coroutines. Coroutines are similar to |
24 |
Threads but don't run in parallel. |
25 |
|
26 |
This module is still experimental, see the BUGS section below. |
27 |
|
28 |
In this module, coroutines are defined as "callchain + lexical variables |
29 |
+ @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own |
30 |
callchain, it's own set of lexicals and it's own set of perl's most |
31 |
important global variables. |
32 |
|
33 |
=cut |
34 |
|
35 |
package Coro; |
36 |
|
37 |
no warnings qw(uninitialized); |
38 |
|
39 |
use Coro::State; |
40 |
|
41 |
use base Exporter; |
42 |
|
43 |
$VERSION = 0.52; |
44 |
|
45 |
@EXPORT = qw(async cede schedule terminate current); |
46 |
%EXPORT_TAGS = ( |
47 |
prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
48 |
); |
49 |
@EXPORT_OK = @{$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 |
} |
81 |
|
82 |
=item $main |
83 |
|
84 |
This coroutine represents the main program. |
85 |
|
86 |
=cut |
87 |
|
88 |
our $main = new Coro; |
89 |
|
90 |
=item $current (or as function: current) |
91 |
|
92 |
The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course). |
93 |
|
94 |
=cut |
95 |
|
96 |
# maybe some other module used Coro::Specific before... |
97 |
if ($current) { |
98 |
$main->{specific} = $current->{specific}; |
99 |
} |
100 |
|
101 |
our $current = $main; |
102 |
|
103 |
sub current() { $current } |
104 |
|
105 |
=item $idle |
106 |
|
107 |
The coroutine to switch to when no other coroutine is running. The default |
108 |
implementation prints "FATAL: deadlock detected" and exits. |
109 |
|
110 |
=cut |
111 |
|
112 |
# should be done using priorities :( |
113 |
our $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. |
120 |
my @destroy; |
121 |
my $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 |
=head2 STATIC METHODS |
142 |
|
143 |
Static methods are actually functions that operate on the current process only. |
144 |
|
145 |
=over 4 |
146 |
|
147 |
=item async { ... } [@args...] |
148 |
|
149 |
Create a new asynchronous process and return it's process object |
150 |
(usually unused). When the sub returns the new process is automatically |
151 |
terminated. |
152 |
|
153 |
# create a new coroutine that just prints its arguments |
154 |
async { |
155 |
print "@_\n"; |
156 |
} 1,2,3,4; |
157 |
|
158 |
The coderef you submit MUST NOT be a closure that refers to variables |
159 |
in an outer scope. This does NOT work. Pass arguments into it instead. |
160 |
|
161 |
=cut |
162 |
|
163 |
sub async(&@) { |
164 |
my $pid = new Coro @_; |
165 |
$manager->ready; # this ensures that the stack is cloned from the manager |
166 |
$pid->ready; |
167 |
$pid; |
168 |
} |
169 |
|
170 |
=item schedule |
171 |
|
172 |
Calls the scheduler. Please note that the current process will not be put |
173 |
into the ready queue, so calling this function usually means you will |
174 |
never be called again. |
175 |
|
176 |
=cut |
177 |
|
178 |
=item cede |
179 |
|
180 |
"Cede" to other processes. This function puts the current process into the |
181 |
ready queue and calls C<schedule>, which has the effect of giving up the |
182 |
current "timeslice" to other coroutines of the same or higher priority. |
183 |
|
184 |
=cut |
185 |
|
186 |
=item terminate [arg...] |
187 |
|
188 |
Terminates the current process. |
189 |
|
190 |
Future versions of this function will allow result arguments. |
191 |
|
192 |
=cut |
193 |
|
194 |
sub terminate { |
195 |
$current->{status} = [@_]; |
196 |
$current->cancel; |
197 |
&schedule; |
198 |
die; # NORETURN |
199 |
} |
200 |
|
201 |
=back |
202 |
|
203 |
# dynamic methods |
204 |
|
205 |
=head2 PROCESS METHODS |
206 |
|
207 |
These are the methods you can call on process objects. |
208 |
|
209 |
=over 4 |
210 |
|
211 |
=item new Coro \&sub [, @args...] |
212 |
|
213 |
Create a new process and return it. When the sub returns the process |
214 |
automatically terminates as if C<terminate> with the returned values were |
215 |
called. To make the process run you must first put it into the ready queue |
216 |
by calling the ready method. |
217 |
|
218 |
=cut |
219 |
|
220 |
sub _newcoro { |
221 |
terminate &{+shift}; |
222 |
} |
223 |
|
224 |
sub new { |
225 |
my $class = shift; |
226 |
bless { |
227 |
_coro_state => (new Coro::State $_[0] && \&_newcoro, @_), |
228 |
}, $class; |
229 |
} |
230 |
|
231 |
=item $process->ready |
232 |
|
233 |
Put the given process into the ready queue. |
234 |
|
235 |
=cut |
236 |
|
237 |
=item $process->cancel |
238 |
|
239 |
Like C<terminate>, but terminates the specified process instead. |
240 |
|
241 |
=cut |
242 |
|
243 |
sub cancel { |
244 |
push @destroy, $_[0]; |
245 |
$manager->ready; |
246 |
&schedule if $current == $_[0]; |
247 |
} |
248 |
|
249 |
=item $process->join |
250 |
|
251 |
Wait until the coroutine terminates and return any values given to the |
252 |
C<terminate> function. C<join> can be called multiple times from multiple |
253 |
processes. |
254 |
|
255 |
=cut |
256 |
|
257 |
sub join { |
258 |
my $self = shift; |
259 |
unless ($self->{status}) { |
260 |
push @{$self->{join}}, $current; |
261 |
&schedule; |
262 |
} |
263 |
wantarray ? @{$self->{status}} : $self->{status}[0]; |
264 |
} |
265 |
|
266 |
=item $oldprio = $process->prio($newprio) |
267 |
|
268 |
Sets (or gets, if the argument is missing) the priority of the |
269 |
process. Higher priority processes get run before lower priority |
270 |
processes. Priorities are smalled signed integer (currently -4 .. +3), |
271 |
that you can refer to using PRIO_xxx constants (use the import tag :prio |
272 |
to get then): |
273 |
|
274 |
PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN |
275 |
3 > 1 > 0 > -1 > -3 > -4 |
276 |
|
277 |
# set priority to HIGH |
278 |
current->prio(PRIO_HIGH); |
279 |
|
280 |
The idle coroutine ($Coro::idle) always has a lower priority than any |
281 |
existing coroutine. |
282 |
|
283 |
Changing the priority of the current process will take effect immediately, |
284 |
but changing the priority of processes in the ready queue (but not |
285 |
running) will only take effect after the next schedule (of that |
286 |
process). This is a bug that will be fixed in some future version. |
287 |
|
288 |
=cut |
289 |
|
290 |
sub prio { |
291 |
my $old = $_[0]{prio}; |
292 |
$_[0]{prio} = $_[1] if @_ > 1; |
293 |
$old; |
294 |
} |
295 |
|
296 |
=item $newprio = $process->nice($change) |
297 |
|
298 |
Similar to C<prio>, but subtract the given value from the priority (i.e. |
299 |
higher values mean lower priority, just as in unix). |
300 |
|
301 |
=cut |
302 |
|
303 |
sub nice { |
304 |
$_[0]{prio} -= $_[1]; |
305 |
} |
306 |
|
307 |
=item $olddesc = $process->desc($newdesc) |
308 |
|
309 |
Sets (or gets in case the argument is missing) the description for this |
310 |
process. This is just a free-form string you can associate with a process. |
311 |
|
312 |
=cut |
313 |
|
314 |
sub desc { |
315 |
my $old = $_[0]{desc}; |
316 |
$_[0]{desc} = $_[1] if @_ > 1; |
317 |
$old; |
318 |
} |
319 |
|
320 |
=back |
321 |
|
322 |
=cut |
323 |
|
324 |
1; |
325 |
|
326 |
=head1 BUGS/LIMITATIONS |
327 |
|
328 |
- you must make very sure that no coro is still active on global destruction. |
329 |
very bad things might happen otherwise (usually segfaults). |
330 |
- this module is not thread-safe. You must only ever use this module from |
331 |
the same thread (this requirement might be loosened in the future to |
332 |
allow per-thread schedulers, but Coro::State does not yet allow this). |
333 |
|
334 |
=head1 SEE ALSO |
335 |
|
336 |
L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>, |
337 |
L<Coro::Signal>, L<Coro::State>, L<Coro::Event>, L<Coro::RWLock>, |
338 |
L<Coro::Handle>, L<Coro::Socket>. |
339 |
|
340 |
=head1 AUTHOR |
341 |
|
342 |
Marc Lehmann <pcg@goof.com> |
343 |
http://www.goof.com/pcg/marc/ |
344 |
|
345 |
=cut |
346 |
|