… | |
… | |
8 | |
8 | |
9 | async { |
9 | async { |
10 | # some asynchronous thread of execution |
10 | # some asynchronous thread of execution |
11 | }; |
11 | }; |
12 | |
12 | |
13 | # alternatively create an async process like this: |
13 | # alternatively create an async coroutine like this: |
14 | |
14 | |
15 | sub some_func : Coro { |
15 | sub some_func : Coro { |
16 | # some more async code |
16 | # some more async code |
17 | } |
17 | } |
18 | |
18 | |
19 | cede; |
19 | cede; |
20 | |
20 | |
21 | =head1 DESCRIPTION |
21 | =head1 DESCRIPTION |
22 | |
22 | |
23 | This module collection manages coroutines. Coroutines are similar to |
23 | This module collection manages coroutines. Coroutines are similar |
24 | Threads but don't run in parallel. |
24 | to threads but don't run in parallel at the same time even on SMP |
|
|
25 | machines. The specific flavor of coroutine used in this module also |
|
|
26 | guarantees you that it will not switch between coroutines unless |
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27 | necessary, at easily-identified points in your program, so locking and |
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28 | parallel access are rarely an issue, making coroutine programming much |
|
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29 | safer than threads programming. |
25 | |
30 | |
26 | This module is still experimental, see the BUGS section below. |
31 | (Perl, however, does not natively support real threads but instead does a |
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32 | very slow and memory-intensive emulation of processes using threads. This |
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33 | is a performance win on Windows machines, and a loss everywhere else). |
27 | |
34 | |
28 | In this module, coroutines are defined as "callchain + lexical variables |
35 | In this module, coroutines are defined as "callchain + lexical variables + |
29 | + @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own |
36 | @_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain, |
30 | callchain, it's own set of lexicals and it's own set of perl's most |
37 | its own set of lexicals and its own set of perls most important global |
31 | important global variables. |
38 | variables. |
32 | |
39 | |
33 | =cut |
40 | =cut |
34 | |
41 | |
35 | package Coro; |
42 | package Coro; |
36 | |
43 | |
|
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44 | use strict; |
|
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45 | no warnings "uninitialized"; |
|
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46 | |
37 | use Coro::State; |
47 | use Coro::State; |
38 | |
48 | |
39 | use base Exporter; |
49 | use base qw(Coro::State Exporter); |
40 | |
50 | |
41 | $VERSION = 0.13; |
51 | our $idle; # idle handler |
|
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52 | our $main; # main coroutine |
|
|
53 | our $current; # current coroutine |
42 | |
54 | |
|
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55 | our $VERSION = '3.7'; |
|
|
56 | |
43 | @EXPORT = qw(async cede schedule terminate current); |
57 | our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); |
44 | @EXPORT_OK = qw($current); |
58 | our %EXPORT_TAGS = ( |
|
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59 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
|
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60 | ); |
|
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61 | our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready)); |
45 | |
62 | |
46 | { |
63 | { |
47 | my @async; |
64 | my @async; |
48 | my $init; |
65 | my $init; |
49 | |
66 | |
50 | # this way of handling attributes simply is NOT scalable ;() |
67 | # this way of handling attributes simply is NOT scalable ;() |
51 | sub import { |
68 | sub import { |
|
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69 | no strict 'refs'; |
|
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70 | |
52 | Coro->export_to_level(1, @_); |
71 | Coro->export_to_level (1, @_); |
|
|
72 | |
53 | my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE}; |
73 | my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE}; |
54 | *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub { |
74 | *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub { |
55 | my ($package, $ref) = (shift, shift); |
75 | my ($package, $ref) = (shift, shift); |
56 | my @attrs; |
76 | my @attrs; |
57 | for (@_) { |
77 | for (@_) { |
… | |
… | |
72 | }; |
92 | }; |
73 | } |
93 | } |
74 | |
94 | |
75 | } |
95 | } |
76 | |
96 | |
|
|
97 | =over 4 |
|
|
98 | |
77 | =item $main |
99 | =item $main |
78 | |
100 | |
79 | This coroutine represents the main program. |
101 | This coroutine represents the main program. |
80 | |
102 | |
81 | =cut |
103 | =cut |
82 | |
104 | |
83 | our $main = new Coro; |
105 | $main = new Coro; |
84 | |
106 | |
85 | =item $current (or as function: current) |
107 | =item $current (or as function: current) |
86 | |
108 | |
87 | The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course). |
109 | The current coroutine (the last coroutine switched to). The initial value |
|
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110 | is C<$main> (of course). |
88 | |
111 | |
|
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112 | This variable is B<strictly> I<read-only>. It is provided for performance |
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113 | reasons. If performance is not essential you are encouraged to use the |
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114 | C<Coro::current> function instead. |
|
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115 | |
89 | =cut |
116 | =cut |
|
|
117 | |
|
|
118 | $main->{desc} = "[main::]"; |
90 | |
119 | |
91 | # maybe some other module used Coro::Specific before... |
120 | # maybe some other module used Coro::Specific before... |
92 | if ($current) { |
|
|
93 | $main->{specific} = $current->{specific}; |
121 | $main->{specific} = $current->{specific} |
94 | } |
122 | if $current; |
95 | |
123 | |
96 | our $current = $main; |
124 | _set_current $main; |
97 | |
125 | |
98 | sub current() { $current } |
126 | sub current() { $current } |
99 | |
127 | |
100 | =item $idle |
128 | =item $idle |
101 | |
129 | |
102 | The coroutine to switch to when no other coroutine is running. The default |
130 | A callback that is called whenever the scheduler finds no ready coroutines |
103 | implementation prints "FATAL: deadlock detected" and exits. |
131 | to run. The default implementation prints "FATAL: deadlock detected" and |
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132 | exits, because the program has no other way to continue. |
104 | |
133 | |
105 | =cut |
134 | This hook is overwritten by modules such as C<Coro::Timer> and |
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135 | C<Coro::Event> to wait on an external event that hopefully wake up a |
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136 | coroutine so the scheduler can run it. |
106 | |
137 | |
107 | # should be done using priorities :( |
138 | Please note that if your callback recursively invokes perl (e.g. for event |
108 | our $idle = new Coro sub { |
139 | handlers), then it must be prepared to be called recursively. |
109 | print STDERR "FATAL: deadlock detected\n"; |
140 | |
110 | exit(51); |
141 | =cut |
|
|
142 | |
|
|
143 | $idle = sub { |
|
|
144 | require Carp; |
|
|
145 | Carp::croak ("FATAL: deadlock detected"); |
111 | }; |
146 | }; |
|
|
147 | |
|
|
148 | sub _cancel { |
|
|
149 | my ($self) = @_; |
|
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150 | |
|
|
151 | # free coroutine data and mark as destructed |
|
|
152 | $self->_destroy |
|
|
153 | or return; |
|
|
154 | |
|
|
155 | # call all destruction callbacks |
|
|
156 | $_->(@{$self->{status}}) |
|
|
157 | for @{(delete $self->{destroy_cb}) || []}; |
|
|
158 | } |
112 | |
159 | |
113 | # this coroutine is necessary because a coroutine |
160 | # this coroutine is necessary because a coroutine |
114 | # cannot destroy itself. |
161 | # cannot destroy itself. |
115 | my @destroy; |
162 | my @destroy; |
|
|
163 | my $manager; |
|
|
164 | |
116 | my $manager = new Coro sub { |
165 | $manager = new Coro sub { |
117 | while() { |
166 | while () { |
118 | delete ((pop @destroy)->{_coro_state}) while @destroy; |
167 | (shift @destroy)->_cancel |
|
|
168 | while @destroy; |
|
|
169 | |
119 | &schedule; |
170 | &schedule; |
120 | } |
171 | } |
121 | }; |
172 | }; |
122 | |
173 | $manager->desc ("[coro manager]"); |
123 | # we really need priorities... |
174 | $manager->prio (PRIO_MAX); |
124 | my @ready; # the ready queue. hehe, rather broken ;) |
|
|
125 | |
175 | |
126 | # static methods. not really. |
176 | # static methods. not really. |
127 | |
177 | |
|
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178 | =back |
|
|
179 | |
128 | =head2 STATIC METHODS |
180 | =head2 STATIC METHODS |
129 | |
181 | |
130 | Static methods are actually functions that operate on the current process only. |
182 | Static methods are actually functions that operate on the current coroutine only. |
131 | |
183 | |
132 | =over 4 |
184 | =over 4 |
133 | |
185 | |
134 | =item async { ... } [@args...] |
186 | =item async { ... } [@args...] |
135 | |
187 | |
136 | Create a new asynchronous process and return it's process object |
188 | Create a new asynchronous coroutine and return it's coroutine object |
137 | (usually unused). When the sub returns the new process is automatically |
189 | (usually unused). When the sub returns the new coroutine is automatically |
138 | terminated. |
190 | terminated. |
|
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191 | |
|
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192 | Calling C<exit> in a coroutine will do the same as calling exit outside |
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193 | the coroutine. Likewise, when the coroutine dies, the program will exit, |
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194 | just as it would in the main program. |
139 | |
195 | |
140 | # create a new coroutine that just prints its arguments |
196 | # create a new coroutine that just prints its arguments |
141 | async { |
197 | async { |
142 | print "@_\n"; |
198 | print "@_\n"; |
143 | } 1,2,3,4; |
199 | } 1,2,3,4; |
144 | |
200 | |
145 | The coderef you submit MUST NOT be a closure that refers to variables |
|
|
146 | in an outer scope. This does NOT work. Pass arguments into it instead. |
|
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147 | |
|
|
148 | =cut |
201 | =cut |
149 | |
202 | |
150 | sub async(&@) { |
203 | sub async(&@) { |
151 | my $pid = new Coro @_; |
204 | my $coro = new Coro @_; |
152 | $manager->ready; # this ensures that the stack is cloned from the manager |
|
|
153 | $pid->ready; |
205 | $coro->ready; |
154 | $pid; |
206 | $coro |
|
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207 | } |
|
|
208 | |
|
|
209 | =item async_pool { ... } [@args...] |
|
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210 | |
|
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211 | Similar to C<async>, but uses a coroutine pool, so you should not call |
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212 | terminate or join (although you are allowed to), and you get a coroutine |
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213 | that might have executed other code already (which can be good or bad :). |
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214 | |
|
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215 | Also, the block is executed in an C<eval> context and a warning will be |
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216 | issued in case of an exception instead of terminating the program, as |
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217 | C<async> does. As the coroutine is being reused, stuff like C<on_destroy> |
|
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218 | will not work in the expected way, unless you call terminate or cancel, |
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219 | which somehow defeats the purpose of pooling. |
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220 | |
|
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221 | The priority will be reset to C<0> after each job, otherwise the coroutine |
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222 | will be re-used "as-is". |
|
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223 | |
|
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224 | The pool size is limited to 8 idle coroutines (this can be adjusted by |
|
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225 | changing $Coro::POOL_SIZE), and there can be as many non-idle coros as |
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226 | required. |
|
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227 | |
|
|
228 | If you are concerned about pooled coroutines growing a lot because a |
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229 | single C<async_pool> used a lot of stackspace you can e.g. C<async_pool |
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230 | { terminate }> once per second or so to slowly replenish the pool. In |
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231 | addition to that, when the stacks used by a handler grows larger than 16kb |
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232 | (adjustable with $Coro::POOL_RSS) it will also exit. |
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233 | |
|
|
234 | =cut |
|
|
235 | |
|
|
236 | our $POOL_SIZE = 8; |
|
|
237 | our $POOL_RSS = 16 * 1024; |
|
|
238 | our @async_pool; |
|
|
239 | |
|
|
240 | sub pool_handler { |
|
|
241 | my $cb; |
|
|
242 | |
|
|
243 | while () { |
|
|
244 | eval { |
|
|
245 | while () { |
|
|
246 | $cb = &_pool_1 |
|
|
247 | or return; |
|
|
248 | |
|
|
249 | &$cb; |
|
|
250 | |
|
|
251 | return if &_pool_2; |
|
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252 | |
|
|
253 | undef $cb; |
|
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254 | schedule; |
|
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255 | } |
|
|
256 | }; |
|
|
257 | |
|
|
258 | warn $@ if $@; |
|
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259 | } |
|
|
260 | } |
|
|
261 | |
|
|
262 | sub async_pool(&@) { |
|
|
263 | # this is also inlined into the unlock_scheduler |
|
|
264 | my $coro = (pop @async_pool) || new Coro \&pool_handler;; |
|
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265 | |
|
|
266 | $coro->{_invoke} = [@_]; |
|
|
267 | $coro->ready; |
|
|
268 | |
|
|
269 | $coro |
155 | } |
270 | } |
156 | |
271 | |
157 | =item schedule |
272 | =item schedule |
158 | |
273 | |
159 | Calls the scheduler. Please note that the current process will not be put |
274 | Calls the scheduler. Please note that the current coroutine will not be put |
160 | into the ready queue, so calling this function usually means you will |
275 | into the ready queue, so calling this function usually means you will |
161 | never be called again. |
276 | never be called again unless something else (e.g. an event handler) calls |
|
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277 | ready. |
162 | |
278 | |
163 | =cut |
279 | The canonical way to wait on external events is this: |
164 | |
280 | |
165 | my $prev; |
281 | { |
|
|
282 | # remember current coroutine |
|
|
283 | my $current = $Coro::current; |
166 | |
284 | |
167 | sub schedule { |
285 | # register a hypothetical event handler |
168 | # should be done using priorities :( |
286 | on_event_invoke sub { |
169 | ($prev, $current) = ($current, shift @ready || $idle); |
287 | # wake up sleeping coroutine |
170 | Coro::State::transfer($prev, $current); |
288 | $current->ready; |
171 | } |
289 | undef $current; |
|
|
290 | }; |
|
|
291 | |
|
|
292 | # call schedule until event occurred. |
|
|
293 | # in case we are woken up for other reasons |
|
|
294 | # (current still defined), loop. |
|
|
295 | Coro::schedule while $current; |
|
|
296 | } |
172 | |
297 | |
173 | =item cede |
298 | =item cede |
174 | |
299 | |
175 | "Cede" to other processes. This function puts the current process into the |
300 | "Cede" to other coroutines. This function puts the current coroutine into the |
176 | ready queue and calls C<schedule>, which has the effect of giving up the |
301 | ready queue and calls C<schedule>, which has the effect of giving up the |
177 | current "timeslice" to other coroutines of the same or higher priority. |
302 | current "timeslice" to other coroutines of the same or higher priority. |
178 | |
303 | |
179 | =cut |
304 | Returns true if at least one coroutine switch has happened. |
180 | |
305 | |
181 | sub cede { |
306 | =item Coro::cede_notself |
182 | $current->ready; |
|
|
183 | &schedule; |
|
|
184 | } |
|
|
185 | |
307 | |
|
|
308 | Works like cede, but is not exported by default and will cede to any |
|
|
309 | coroutine, regardless of priority, once. |
|
|
310 | |
|
|
311 | Returns true if at least one coroutine switch has happened. |
|
|
312 | |
186 | =item terminate |
313 | =item terminate [arg...] |
187 | |
314 | |
188 | Terminates the current process. |
315 | Terminates the current coroutine with the given status values (see L<cancel>). |
189 | |
|
|
190 | Future versions of this function will allow result arguments. |
|
|
191 | |
316 | |
192 | =cut |
317 | =cut |
193 | |
318 | |
194 | sub terminate { |
319 | sub terminate { |
195 | $current->cancel; |
320 | $current->cancel (@_); |
196 | &schedule; |
|
|
197 | die; # NORETURN |
|
|
198 | } |
321 | } |
199 | |
322 | |
200 | =back |
323 | =back |
201 | |
324 | |
202 | # dynamic methods |
325 | # dynamic methods |
203 | |
326 | |
204 | =head2 PROCESS METHODS |
327 | =head2 COROUTINE METHODS |
205 | |
328 | |
206 | These are the methods you can call on process objects. |
329 | These are the methods you can call on coroutine objects. |
207 | |
330 | |
208 | =over 4 |
331 | =over 4 |
209 | |
332 | |
210 | =item new Coro \&sub [, @args...] |
333 | =item new Coro \&sub [, @args...] |
211 | |
334 | |
212 | Create a new process and return it. When the sub returns the process |
335 | Create a new coroutine and return it. When the sub returns the coroutine |
213 | automatically terminates. To start the process you must first put it into |
336 | automatically terminates as if C<terminate> with the returned values were |
|
|
337 | called. To make the coroutine run you must first put it into the ready queue |
214 | the ready queue by calling the ready method. |
338 | by calling the ready method. |
215 | |
339 | |
216 | The coderef you submit MUST NOT be a closure that refers to variables |
340 | See C<async> for additional discussion. |
217 | in an outer scope. This does NOT work. Pass arguments into it instead. |
|
|
218 | |
341 | |
219 | =cut |
342 | =cut |
220 | |
343 | |
221 | sub _newcoro { |
344 | sub _run_coro { |
222 | terminate &{+shift}; |
345 | terminate &{+shift}; |
223 | } |
346 | } |
224 | |
347 | |
225 | sub new { |
348 | sub new { |
226 | my $class = shift; |
349 | my $class = shift; |
227 | bless { |
|
|
228 | _coro_state => (new Coro::State $_[0] && \&_newcoro, @_), |
|
|
229 | }, $class; |
|
|
230 | } |
|
|
231 | |
350 | |
232 | =item $process->ready |
351 | $class->SUPER::new (\&_run_coro, @_) |
233 | |
|
|
234 | Put the current process into the ready queue. |
|
|
235 | |
|
|
236 | =cut |
|
|
237 | |
|
|
238 | sub ready { |
|
|
239 | push @ready, $_[0]; |
|
|
240 | } |
352 | } |
241 | |
353 | |
242 | =item $process->cancel |
354 | =item $success = $coroutine->ready |
243 | |
355 | |
244 | Like C<terminate>, but terminates the specified process instead. |
356 | Put the given coroutine into the ready queue (according to it's priority) |
|
|
357 | and return true. If the coroutine is already in the ready queue, do nothing |
|
|
358 | and return false. |
|
|
359 | |
|
|
360 | =item $is_ready = $coroutine->is_ready |
|
|
361 | |
|
|
362 | Return wether the coroutine is currently the ready queue or not, |
|
|
363 | |
|
|
364 | =item $coroutine->cancel (arg...) |
|
|
365 | |
|
|
366 | Terminates the given coroutine and makes it return the given arguments as |
|
|
367 | status (default: the empty list). Never returns if the coroutine is the |
|
|
368 | current coroutine. |
245 | |
369 | |
246 | =cut |
370 | =cut |
247 | |
371 | |
248 | sub cancel { |
372 | sub cancel { |
|
|
373 | my $self = shift; |
|
|
374 | $self->{status} = [@_]; |
|
|
375 | |
|
|
376 | if ($current == $self) { |
249 | push @destroy, $_[0]; |
377 | push @destroy, $self; |
250 | $manager->ready; |
378 | $manager->ready; |
|
|
379 | &schedule while 1; |
|
|
380 | } else { |
|
|
381 | $self->_cancel; |
|
|
382 | } |
|
|
383 | } |
|
|
384 | |
|
|
385 | =item $coroutine->join |
|
|
386 | |
|
|
387 | Wait until the coroutine terminates and return any values given to the |
|
|
388 | C<terminate> or C<cancel> functions. C<join> can be called multiple times |
|
|
389 | from multiple coroutine. |
|
|
390 | |
|
|
391 | =cut |
|
|
392 | |
|
|
393 | sub join { |
|
|
394 | my $self = shift; |
|
|
395 | |
|
|
396 | unless ($self->{status}) { |
|
|
397 | my $current = $current; |
|
|
398 | |
|
|
399 | push @{$self->{destroy_cb}}, sub { |
|
|
400 | $current->ready; |
|
|
401 | undef $current; |
|
|
402 | }; |
|
|
403 | |
|
|
404 | &schedule while $current; |
|
|
405 | } |
|
|
406 | |
|
|
407 | wantarray ? @{$self->{status}} : $self->{status}[0]; |
|
|
408 | } |
|
|
409 | |
|
|
410 | =item $coroutine->on_destroy (\&cb) |
|
|
411 | |
|
|
412 | Registers a callback that is called when this coroutine gets destroyed, |
|
|
413 | but before it is joined. The callback gets passed the terminate arguments, |
|
|
414 | if any. |
|
|
415 | |
|
|
416 | =cut |
|
|
417 | |
|
|
418 | sub on_destroy { |
|
|
419 | my ($self, $cb) = @_; |
|
|
420 | |
|
|
421 | push @{ $self->{destroy_cb} }, $cb; |
|
|
422 | } |
|
|
423 | |
|
|
424 | =item $oldprio = $coroutine->prio ($newprio) |
|
|
425 | |
|
|
426 | Sets (or gets, if the argument is missing) the priority of the |
|
|
427 | coroutine. Higher priority coroutines get run before lower priority |
|
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428 | coroutines. Priorities are small signed integers (currently -4 .. +3), |
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429 | that you can refer to using PRIO_xxx constants (use the import tag :prio |
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430 | to get then): |
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431 | |
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432 | PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN |
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433 | 3 > 1 > 0 > -1 > -3 > -4 |
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434 | |
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435 | # set priority to HIGH |
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436 | current->prio(PRIO_HIGH); |
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437 | |
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438 | The idle coroutine ($Coro::idle) always has a lower priority than any |
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439 | existing coroutine. |
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440 | |
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441 | Changing the priority of the current coroutine will take effect immediately, |
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442 | but changing the priority of coroutines in the ready queue (but not |
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443 | running) will only take effect after the next schedule (of that |
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444 | coroutine). This is a bug that will be fixed in some future version. |
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445 | |
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446 | =item $newprio = $coroutine->nice ($change) |
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447 | |
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448 | Similar to C<prio>, but subtract the given value from the priority (i.e. |
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449 | higher values mean lower priority, just as in unix). |
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450 | |
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451 | =item $olddesc = $coroutine->desc ($newdesc) |
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452 | |
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453 | Sets (or gets in case the argument is missing) the description for this |
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454 | coroutine. This is just a free-form string you can associate with a coroutine. |
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455 | |
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456 | =cut |
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457 | |
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458 | sub desc { |
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459 | my $old = $_[0]{desc}; |
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460 | $_[0]{desc} = $_[1] if @_ > 1; |
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461 | $old; |
251 | } |
462 | } |
252 | |
463 | |
253 | =back |
464 | =back |
254 | |
465 | |
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466 | =head2 GLOBAL FUNCTIONS |
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467 | |
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468 | =over 4 |
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469 | |
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470 | =item Coro::nready |
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471 | |
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472 | Returns the number of coroutines that are currently in the ready state, |
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473 | i.e. that can be switched to. The value C<0> means that the only runnable |
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474 | coroutine is the currently running one, so C<cede> would have no effect, |
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475 | and C<schedule> would cause a deadlock unless there is an idle handler |
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476 | that wakes up some coroutines. |
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477 | |
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478 | =item my $guard = Coro::guard { ... } |
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479 | |
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480 | This creates and returns a guard object. Nothing happens until the object |
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481 | gets destroyed, in which case the codeblock given as argument will be |
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482 | executed. This is useful to free locks or other resources in case of a |
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483 | runtime error or when the coroutine gets canceled, as in both cases the |
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484 | guard block will be executed. The guard object supports only one method, |
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485 | C<< ->cancel >>, which will keep the codeblock from being executed. |
|
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486 | |
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487 | Example: set some flag and clear it again when the coroutine gets canceled |
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488 | or the function returns: |
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489 | |
|
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490 | sub do_something { |
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491 | my $guard = Coro::guard { $busy = 0 }; |
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492 | $busy = 1; |
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493 | |
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494 | # do something that requires $busy to be true |
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495 | } |
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496 | |
|
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497 | =cut |
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498 | |
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499 | sub guard(&) { |
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500 | bless \(my $cb = $_[0]), "Coro::guard" |
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501 | } |
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502 | |
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503 | sub Coro::guard::cancel { |
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504 | ${$_[0]} = sub { }; |
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505 | } |
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506 | |
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507 | sub Coro::guard::DESTROY { |
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508 | ${$_[0]}->(); |
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509 | } |
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510 | |
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511 | |
|
|
512 | =item unblock_sub { ... } |
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513 | |
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514 | This utility function takes a BLOCK or code reference and "unblocks" it, |
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515 | returning the new coderef. This means that the new coderef will return |
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516 | immediately without blocking, returning nothing, while the original code |
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517 | ref will be called (with parameters) from within its own coroutine. |
|
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518 | |
|
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519 | The reason this function exists is that many event libraries (such as the |
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520 | venerable L<Event|Event> module) are not coroutine-safe (a weaker form |
|
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521 | of thread-safety). This means you must not block within event callbacks, |
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522 | otherwise you might suffer from crashes or worse. |
|
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523 | |
|
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524 | This function allows your callbacks to block by executing them in another |
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525 | coroutine where it is safe to block. One example where blocking is handy |
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526 | is when you use the L<Coro::AIO|Coro::AIO> functions to save results to |
|
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527 | disk. |
|
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528 | |
|
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529 | In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when |
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530 | creating event callbacks that want to block. |
|
|
531 | |
|
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532 | =cut |
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533 | |
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|
534 | our @unblock_queue; |
|
|
535 | |
|
|
536 | # we create a special coro because we want to cede, |
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537 | # to reduce pressure on the coro pool (because most callbacks |
|
|
538 | # return immediately and can be reused) and because we cannot cede |
|
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539 | # inside an event callback. |
|
|
540 | our $unblock_scheduler = new Coro sub { |
|
|
541 | while () { |
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542 | while (my $cb = pop @unblock_queue) { |
|
|
543 | # this is an inlined copy of async_pool |
|
|
544 | my $coro = (pop @async_pool) || new Coro \&pool_handler; |
|
|
545 | |
|
|
546 | $coro->{_invoke} = $cb; |
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547 | $coro->ready; |
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548 | cede; # for short-lived callbacks, this reduces pressure on the coro pool |
|
|
549 | } |
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550 | schedule; # sleep well |
|
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551 | } |
|
|
552 | }; |
|
|
553 | $unblock_scheduler->desc ("[unblock_sub scheduler]"); |
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554 | |
|
|
555 | sub unblock_sub(&) { |
|
|
556 | my $cb = shift; |
|
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557 | |
|
|
558 | sub { |
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559 | unshift @unblock_queue, [$cb, @_]; |
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|
560 | $unblock_scheduler->ready; |
|
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561 | } |
|
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562 | } |
|
|
563 | |
|
|
564 | =back |
|
|
565 | |
255 | =cut |
566 | =cut |
256 | |
567 | |
257 | 1; |
568 | 1; |
258 | |
569 | |
259 | =head1 BUGS/LIMITATIONS |
570 | =head1 BUGS/LIMITATIONS |
260 | |
571 | |
261 | - could be faster, especially when the core would introduce special |
572 | - you must make very sure that no coro is still active on global |
262 | support for coroutines (like it does for threads). |
573 | destruction. very bad things might happen otherwise (usually segfaults). |
263 | - there is still a memleak on coroutine termination that I could not |
574 | |
264 | identify. Could be as small as a single SV. |
|
|
265 | - this module is not well-tested. |
|
|
266 | - if variables or arguments "disappear" (become undef) or become |
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|
267 | corrupted please contact the author so he cen iron out the |
|
|
268 | remaining bugs. |
|
|
269 | - this module is not thread-safe. You must only ever use this module from |
575 | - this module is not thread-safe. You should only ever use this module |
270 | the same thread (this requirement might be loosened in the future to |
576 | from the same thread (this requirement might be loosened in the future |
271 | allow per-thread schedulers, but Coro::State does not yet allow this). |
577 | to allow per-thread schedulers, but Coro::State does not yet allow |
|
|
578 | this). |
272 | |
579 | |
273 | =head1 SEE ALSO |
580 | =head1 SEE ALSO |
274 | |
581 | |
275 | L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>, |
582 | Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>. |
276 | L<Coro::Signal>, L<Coro::State>, L<Coro::Event>, L<Coro::RWLock>, |
583 | |
277 | L<Coro::Handle>, L<Coro::Socket>. |
584 | Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>. |
|
|
585 | |
|
|
586 | Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>. |
|
|
587 | |
|
|
588 | Embedding: L<Coro:MakeMaker> |
278 | |
589 | |
279 | =head1 AUTHOR |
590 | =head1 AUTHOR |
280 | |
591 | |
281 | Marc Lehmann <pcg@goof.com> |
592 | Marc Lehmann <schmorp@schmorp.de> |
282 | http://www.goof.com/pcg/marc/ |
593 | http://home.schmorp.de/ |
283 | |
594 | |
284 | =cut |
595 | =cut |
285 | |
596 | |