1 | =head1 NAME |
1 | =head1 NAME |
2 | |
2 | |
3 | Coro - coroutine process abstraction |
3 | Coro - the real perl threads |
4 | |
4 | |
5 | =head1 SYNOPSIS |
5 | =head1 SYNOPSIS |
6 | |
6 | |
7 | use Coro; |
7 | use Coro; |
8 | |
8 | |
… | |
… | |
26 | $locked = 1; |
26 | $locked = 1; |
27 | $lock->up; |
27 | $lock->up; |
28 | |
28 | |
29 | =head1 DESCRIPTION |
29 | =head1 DESCRIPTION |
30 | |
30 | |
31 | This module collection manages coroutines. Coroutines are similar to |
31 | This module collection manages coroutines, that is, cooperative |
32 | threads but don't (in general) run in parallel at the same time even |
32 | threads. Coroutines are similar to kernel threads but don't (in general) |
33 | on SMP machines. The specific flavor of coroutine used in this module |
33 | run in parallel at the same time even on SMP machines. The specific flavor |
34 | also guarantees you that it will not switch between coroutines unless |
34 | of coroutine used in this module also guarantees you that it will not |
35 | necessary, at easily-identified points in your program, so locking and |
35 | switch between coroutines unless necessary, at easily-identified points |
36 | parallel access are rarely an issue, making coroutine programming much |
36 | in your program, so locking and parallel access are rarely an issue, |
37 | safer and easier than threads programming. |
37 | making coroutine programming much safer and easier than using other thread |
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38 | models. |
38 | |
39 | |
39 | Unlike a normal perl program, however, coroutines allow you to have |
40 | Unlike the so-called "Perl threads" (which are not actually real threads |
40 | multiple running interpreters that share data, which is especially useful |
41 | but only the windows process emulation ported to unix), Coro provides a |
41 | to code pseudo-parallel processes and for event-based programming, such as |
42 | full shared address space, which makes communication between coroutines |
42 | multiple HTTP-GET requests running concurrently. See L<Coro::AnyEvent> to |
43 | very easy. And coroutines are fast, too: disabling the Windows process |
43 | learn more. |
44 | emulation code in your perl and using Coro can easily result in a two to |
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45 | four times speed increase for your programs. |
44 | |
46 | |
45 | Coroutines are also useful because Perl has no support for threads (the so |
47 | Coro achieves that by supporting multiple running interpreters that share |
46 | called "threads" that perl offers are nothing more than the (bad) process |
48 | data, which is especially useful to code pseudo-parallel processes and |
47 | emulation coming from the Windows platform: On standard operating systems |
49 | for event-based programming, such as multiple HTTP-GET requests running |
48 | they serve no purpose whatsoever, except by making your programs slow and |
50 | concurrently. See L<Coro::AnyEvent> to learn more on how to integrate Coro |
49 | making them use a lot of memory. Best disable them when building perl, or |
51 | into an event-based environment. |
50 | aks your software vendor/distributor to do it for you). |
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51 | |
52 | |
52 | In this module, coroutines are defined as "callchain + lexical variables + |
53 | In this module, a coroutines is defined as "callchain + lexical variables |
53 | @_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain, |
54 | + @_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own |
54 | its own set of lexicals and its own set of perls most important global |
55 | callchain, its own set of lexicals and its own set of perls most important |
55 | variables (see L<Coro::State> for more configuration). |
56 | global variables (see L<Coro::State> for more configuration and background |
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57 | info). |
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58 | |
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59 | See also the C<SEE ALSO> section at the end of this document - the Coro |
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60 | module family is quite large. |
56 | |
61 | |
57 | =cut |
62 | =cut |
58 | |
63 | |
59 | package Coro; |
64 | package Coro; |
60 | |
65 | |
61 | use strict; |
66 | use strict qw(vars subs); |
62 | no warnings "uninitialized"; |
67 | no warnings "uninitialized"; |
63 | |
68 | |
64 | use Coro::State; |
69 | use Coro::State; |
65 | |
70 | |
66 | use base qw(Coro::State Exporter); |
71 | use base qw(Coro::State Exporter); |
67 | |
72 | |
68 | our $idle; # idle handler |
73 | our $idle; # idle handler |
69 | our $main; # main coroutine |
74 | our $main; # main coroutine |
70 | our $current; # current coroutine |
75 | our $current; # current coroutine |
71 | |
76 | |
72 | our $VERSION = 4.802; |
77 | our $VERSION = "5.0"; |
73 | |
78 | |
74 | our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); |
79 | our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); |
75 | our %EXPORT_TAGS = ( |
80 | our %EXPORT_TAGS = ( |
76 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
81 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
77 | ); |
82 | ); |
78 | our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready)); |
83 | our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready)); |
79 | |
84 | |
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85 | =head1 GLOBAL VARIABLES |
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86 | |
80 | =over 4 |
87 | =over 4 |
81 | |
88 | |
82 | =item $Coro::main |
89 | =item $Coro::main |
83 | |
90 | |
84 | This variable stores the coroutine object that represents the main |
91 | This variable stores the coroutine object that represents the main |
… | |
… | |
86 | coroutines, it is mainly useful to compare again C<$Coro::current>, to see |
93 | coroutines, it is mainly useful to compare again C<$Coro::current>, to see |
87 | whether you are running in the main program or not. |
94 | whether you are running in the main program or not. |
88 | |
95 | |
89 | =cut |
96 | =cut |
90 | |
97 | |
91 | $main = new Coro; |
98 | # $main is now being initialised by Coro::State |
92 | |
99 | |
93 | =item $Coro::current |
100 | =item $Coro::current |
94 | |
101 | |
95 | The coroutine object representing the current coroutine (the last |
102 | The coroutine object representing the current coroutine (the last |
96 | coroutine that the Coro scheduler switched to). The initial value is |
103 | coroutine that the Coro scheduler switched to). The initial value is |
97 | C<$main> (of course). |
104 | C<$Coro::main> (of course). |
98 | |
105 | |
99 | This variable is B<strictly> I<read-only>. You can take copies of the |
106 | This variable is B<strictly> I<read-only>. You can take copies of the |
100 | value stored in it and use it as any other coroutine object, but you must |
107 | value stored in it and use it as any other coroutine object, but you must |
101 | not otherwise modify the variable itself. |
108 | not otherwise modify the variable itself. |
102 | |
109 | |
103 | =cut |
110 | =cut |
104 | |
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105 | $main->{desc} = "[main::]"; |
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106 | |
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107 | # maybe some other module used Coro::Specific before... |
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108 | $main->{_specific} = $current->{_specific} |
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109 | if $current; |
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110 | |
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111 | _set_current $main; |
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112 | |
111 | |
113 | sub current() { $current } # [DEPRECATED] |
112 | sub current() { $current } # [DEPRECATED] |
114 | |
113 | |
115 | =item $Coro::idle |
114 | =item $Coro::idle |
116 | |
115 | |
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143 | $idle = sub { |
142 | $idle = sub { |
144 | require Carp; |
143 | require Carp; |
145 | Carp::croak ("FATAL: deadlock detected"); |
144 | Carp::croak ("FATAL: deadlock detected"); |
146 | }; |
145 | }; |
147 | |
146 | |
148 | sub _cancel { |
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149 | my ($self) = @_; |
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150 | |
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151 | # free coroutine data and mark as destructed |
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152 | $self->_destroy |
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153 | or return; |
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154 | |
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155 | # call all destruction callbacks |
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156 | $_->(@{$self->{_status}}) |
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157 | for @{(delete $self->{_on_destroy}) || []}; |
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158 | } |
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159 | |
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160 | # this coroutine is necessary because a coroutine |
147 | # this coroutine is necessary because a coroutine |
161 | # cannot destroy itself. |
148 | # cannot destroy itself. |
162 | my @destroy; |
149 | our @destroy; |
163 | my $manager; |
150 | our $manager; |
164 | |
151 | |
165 | $manager = new Coro sub { |
152 | $manager = new Coro sub { |
166 | while () { |
153 | while () { |
167 | (shift @destroy)->_cancel |
154 | Coro::_cancel shift @destroy |
168 | while @destroy; |
155 | while @destroy; |
169 | |
156 | |
170 | &schedule; |
157 | &schedule; |
171 | } |
158 | } |
172 | }; |
159 | }; |
173 | $manager->desc ("[coro manager]"); |
160 | $manager->{desc} = "[coro manager]"; |
174 | $manager->prio (PRIO_MAX); |
161 | $manager->prio (PRIO_MAX); |
175 | |
162 | |
176 | =back |
163 | =back |
177 | |
164 | |
178 | =head2 SIMPLE COROUTINE CREATION |
165 | =head1 SIMPLE COROUTINE CREATION |
179 | |
166 | |
180 | =over 4 |
167 | =over 4 |
181 | |
168 | |
182 | =item async { ... } [@args...] |
169 | =item async { ... } [@args...] |
183 | |
170 | |
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220 | Similar to C<async>, but uses a coroutine pool, so you should not call |
207 | Similar to C<async>, but uses a coroutine pool, so you should not call |
221 | terminate or join on it (although you are allowed to), and you get a |
208 | terminate or join on it (although you are allowed to), and you get a |
222 | coroutine that might have executed other code already (which can be good |
209 | coroutine that might have executed other code already (which can be good |
223 | or bad :). |
210 | or bad :). |
224 | |
211 | |
225 | On the plus side, this function is faster than creating (and destroying) |
212 | On the plus side, this function is about twice as fast as creating (and |
226 | a completly new coroutine, so if you need a lot of generic coroutines in |
213 | destroying) a completely new coroutine, so if you need a lot of generic |
227 | quick successsion, use C<async_pool>, not C<async>. |
214 | coroutines in quick successsion, use C<async_pool>, not C<async>. |
228 | |
215 | |
229 | The code block is executed in an C<eval> context and a warning will be |
216 | The code block is executed in an C<eval> context and a warning will be |
230 | issued in case of an exception instead of terminating the program, as |
217 | issued in case of an exception instead of terminating the program, as |
231 | C<async> does. As the coroutine is being reused, stuff like C<on_destroy> |
218 | C<async> does. As the coroutine is being reused, stuff like C<on_destroy> |
232 | will not work in the expected way, unless you call terminate or cancel, |
219 | will not work in the expected way, unless you call terminate or cancel, |
… | |
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245 | coros as required. |
232 | coros as required. |
246 | |
233 | |
247 | If you are concerned about pooled coroutines growing a lot because a |
234 | If you are concerned about pooled coroutines growing a lot because a |
248 | single C<async_pool> used a lot of stackspace you can e.g. C<async_pool |
235 | single C<async_pool> used a lot of stackspace you can e.g. C<async_pool |
249 | { terminate }> once per second or so to slowly replenish the pool. In |
236 | { terminate }> once per second or so to slowly replenish the pool. In |
250 | addition to that, when the stacks used by a handler grows larger than 16kb |
237 | addition to that, when the stacks used by a handler grows larger than 32kb |
251 | (adjustable via $Coro::POOL_RSS) it will also be destroyed. |
238 | (adjustable via $Coro::POOL_RSS) it will also be destroyed. |
252 | |
239 | |
253 | =cut |
240 | =cut |
254 | |
241 | |
255 | our $POOL_SIZE = 8; |
242 | our $POOL_SIZE = 8; |
256 | our $POOL_RSS = 16 * 1024; |
243 | our $POOL_RSS = 32 * 1024; |
257 | our @async_pool; |
244 | our @async_pool; |
258 | |
245 | |
259 | sub pool_handler { |
246 | sub pool_handler { |
260 | my $cb; |
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261 | |
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262 | while () { |
247 | while () { |
263 | eval { |
248 | eval { |
264 | while () { |
249 | &{&_pool_handler} while 1; |
265 | _pool_1 $cb; |
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266 | &$cb; |
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267 | _pool_2 $cb; |
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268 | &schedule; |
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269 | } |
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270 | }; |
250 | }; |
271 | |
251 | |
272 | if ($@) { |
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273 | last if $@ eq "\3async_pool terminate\2\n"; |
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274 | warn $@; |
252 | warn $@ if $@; |
275 | } |
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276 | } |
253 | } |
277 | } |
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278 | |
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279 | sub async_pool(&@) { |
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280 | # this is also inlined into the unlock_scheduler |
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281 | my $coro = (pop @async_pool) || new Coro \&pool_handler; |
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282 | |
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283 | $coro->{_invoke} = [@_]; |
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284 | $coro->ready; |
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285 | |
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286 | $coro |
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287 | } |
254 | } |
288 | |
255 | |
289 | =back |
256 | =back |
290 | |
257 | |
291 | =head2 STATIC METHODS |
258 | =head1 STATIC METHODS |
292 | |
259 | |
293 | Static methods are actually functions that operate on the current coroutine. |
260 | Static methods are actually functions that implicitly operate on the |
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261 | current coroutine. |
294 | |
262 | |
295 | =over 4 |
263 | =over 4 |
296 | |
264 | |
297 | =item schedule |
265 | =item schedule |
298 | |
266 | |
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313 | >> on that once some event happens, and last you call C<schedule> to put |
281 | >> on that once some event happens, and last you call C<schedule> to put |
314 | yourself to sleep. Note that a lot of things can wake your coroutine up, |
282 | yourself to sleep. Note that a lot of things can wake your coroutine up, |
315 | so you need to check whether the event indeed happened, e.g. by storing the |
283 | so you need to check whether the event indeed happened, e.g. by storing the |
316 | status in a variable. |
284 | status in a variable. |
317 | |
285 | |
318 | The canonical way to wait on external events is this: |
286 | See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks. |
319 | |
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320 | { |
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321 | # remember current coroutine |
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322 | my $current = $Coro::current; |
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323 | |
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324 | # register a hypothetical event handler |
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325 | on_event_invoke sub { |
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326 | # wake up sleeping coroutine |
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327 | $current->ready; |
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328 | undef $current; |
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329 | }; |
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330 | |
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331 | # call schedule until event occurred. |
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332 | # in case we are woken up for other reasons |
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333 | # (current still defined), loop. |
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334 | Coro::schedule while $current; |
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335 | } |
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336 | |
287 | |
337 | =item cede |
288 | =item cede |
338 | |
289 | |
339 | "Cede" to other coroutines. This function puts the current coroutine into |
290 | "Cede" to other coroutines. This function puts the current coroutine into |
340 | the ready queue and calls C<schedule>, which has the effect of giving |
291 | the ready queue and calls C<schedule>, which has the effect of giving |
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364 | you cannot free all of them, so if a coroutine that is not the main |
315 | you cannot free all of them, so if a coroutine that is not the main |
365 | program calls this function, there will be some one-time resource leak. |
316 | program calls this function, there will be some one-time resource leak. |
366 | |
317 | |
367 | =cut |
318 | =cut |
368 | |
319 | |
369 | sub terminate { |
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370 | $current->cancel (@_); |
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371 | } |
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372 | |
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373 | sub killall { |
320 | sub killall { |
374 | for (Coro::State::list) { |
321 | for (Coro::State::list) { |
375 | $_->cancel |
322 | $_->cancel |
376 | if $_ != $current && UNIVERSAL::isa $_, "Coro"; |
323 | if $_ != $current && UNIVERSAL::isa $_, "Coro"; |
377 | } |
324 | } |
378 | } |
325 | } |
379 | |
326 | |
380 | =back |
327 | =back |
381 | |
328 | |
382 | =head2 COROUTINE METHODS |
329 | =head1 COROUTINE OBJECT METHODS |
383 | |
330 | |
384 | These are the methods you can call on coroutine objects (or to create |
331 | These are the methods you can call on coroutine objects (or to create |
385 | them). |
332 | them). |
386 | |
333 | |
387 | =over 4 |
334 | =over 4 |
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396 | See C<async> and C<Coro::State::new> for additional info about the |
343 | See C<async> and C<Coro::State::new> for additional info about the |
397 | coroutine environment. |
344 | coroutine environment. |
398 | |
345 | |
399 | =cut |
346 | =cut |
400 | |
347 | |
401 | sub _run_coro { |
348 | sub _terminate { |
402 | terminate &{+shift}; |
349 | terminate &{+shift}; |
403 | } |
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404 | |
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405 | sub new { |
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406 | my $class = shift; |
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407 | |
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408 | $class->SUPER::new (\&_run_coro, @_) |
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409 | } |
350 | } |
410 | |
351 | |
411 | =item $success = $coroutine->ready |
352 | =item $success = $coroutine->ready |
412 | |
353 | |
413 | Put the given coroutine into the end of its ready queue (there is one |
354 | Put the given coroutine into the end of its ready queue (there is one |
… | |
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430 | |
371 | |
431 | =cut |
372 | =cut |
432 | |
373 | |
433 | sub cancel { |
374 | sub cancel { |
434 | my $self = shift; |
375 | my $self = shift; |
435 | $self->{_status} = [@_]; |
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436 | |
376 | |
437 | if ($current == $self) { |
377 | if ($current == $self) { |
438 | push @destroy, $self; |
378 | terminate @_; |
439 | $manager->ready; |
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440 | &schedule while 1; |
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441 | } else { |
379 | } else { |
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380 | $self->{_status} = [@_]; |
442 | $self->_cancel; |
381 | $self->_cancel; |
443 | } |
382 | } |
444 | } |
383 | } |
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384 | |
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385 | =item $coroutine->schedule_to |
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386 | |
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387 | Puts the current coroutine to sleep (like C<Coro::schedule>), but instead |
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388 | of continuing with the next coro from the ready queue, always switch to |
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389 | the given coroutine object (regardless of priority etc.). The readyness |
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390 | state of that coroutine isn't changed. |
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391 | |
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392 | This is an advanced method for special cases - I'd love to hear about any |
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393 | uses for this one. |
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394 | |
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395 | =item $coroutine->cede_to |
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396 | |
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397 | Like C<schedule_to>, but puts the current coroutine into the ready |
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398 | queue. This has the effect of temporarily switching to the given |
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399 | coroutine, and continuing some time later. |
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400 | |
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401 | This is an advanced method for special cases - I'd love to hear about any |
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402 | uses for this one. |
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403 | |
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404 | =item $coroutine->throw ([$scalar]) |
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405 | |
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406 | If C<$throw> is specified and defined, it will be thrown as an exception |
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407 | inside the coroutine at the next convenient point in time. Otherwise |
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408 | clears the exception object. |
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409 | |
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410 | Coro will check for the exception each time a schedule-like-function |
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411 | returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down |
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412 | >>, C<< Coro::Handle->readable >> and so on. Most of these functions |
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413 | detect this case and return early in case an exception is pending. |
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414 | |
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415 | The exception object will be thrown "as is" with the specified scalar in |
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416 | C<$@>, i.e. if it is a string, no line number or newline will be appended |
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417 | (unlike with C<die>). |
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418 | |
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419 | This can be used as a softer means than C<cancel> to ask a coroutine to |
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420 | end itself, although there is no guarantee that the exception will lead to |
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421 | termination, and if the exception isn't caught it might well end the whole |
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422 | program. |
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423 | |
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424 | You might also think of C<throw> as being the moral equivalent of |
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425 | C<kill>ing a coroutine with a signal (in this case, a scalar). |
445 | |
426 | |
446 | =item $coroutine->join |
427 | =item $coroutine->join |
447 | |
428 | |
448 | Wait until the coroutine terminates and return any values given to the |
429 | Wait until the coroutine terminates and return any values given to the |
449 | C<terminate> or C<cancel> functions. C<join> can be called concurrently |
430 | C<terminate> or C<cancel> functions. C<join> can be called concurrently |
… | |
… | |
511 | higher values mean lower priority, just as in unix). |
492 | higher values mean lower priority, just as in unix). |
512 | |
493 | |
513 | =item $olddesc = $coroutine->desc ($newdesc) |
494 | =item $olddesc = $coroutine->desc ($newdesc) |
514 | |
495 | |
515 | Sets (or gets in case the argument is missing) the description for this |
496 | Sets (or gets in case the argument is missing) the description for this |
516 | coroutine. This is just a free-form string you can associate with a coroutine. |
497 | coroutine. This is just a free-form string you can associate with a |
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498 | coroutine. |
517 | |
499 | |
518 | This method simply sets the C<< $coroutine->{desc} >> member to the given string. You |
500 | This method simply sets the C<< $coroutine->{desc} >> member to the given |
519 | can modify this member directly if you wish. |
501 | string. You can modify this member directly if you wish. |
520 | |
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521 | =item $coroutine->throw ([$scalar]) |
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522 | |
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523 | If C<$throw> is specified and defined, it will be thrown as an exception |
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524 | inside the coroutine at the next convinient point in time (usually after |
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525 | it gains control at the next schedule/transfer/cede). Otherwise clears the |
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526 | exception object. |
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527 | |
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528 | The exception object will be thrown "as is" with the specified scalar in |
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529 | C<$@>, i.e. if it is a string, no line number or newline will be appended |
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530 | (unlike with C<die>). |
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531 | |
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532 | This can be used as a softer means than C<cancel> to ask a coroutine to |
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533 | end itself, although there is no guarentee that the exception will lead to |
|
|
534 | termination, and if the exception isn't caught it might well end the whole |
|
|
535 | program. |
|
|
536 | |
502 | |
537 | =cut |
503 | =cut |
538 | |
504 | |
539 | sub desc { |
505 | sub desc { |
540 | my $old = $_[0]{desc}; |
506 | my $old = $_[0]{desc}; |
541 | $_[0]{desc} = $_[1] if @_ > 1; |
507 | $_[0]{desc} = $_[1] if @_ > 1; |
542 | $old; |
508 | $old; |
543 | } |
509 | } |
544 | |
510 | |
|
|
511 | sub transfer { |
|
|
512 | require Carp; |
|
|
513 | Carp::croak ("You must not call ->transfer on Coro objects. Use Coro::State objects or the ->schedule_to method. Caught"); |
|
|
514 | } |
|
|
515 | |
545 | =back |
516 | =back |
546 | |
517 | |
547 | =head2 GLOBAL FUNCTIONS |
518 | =head1 GLOBAL FUNCTIONS |
548 | |
519 | |
549 | =over 4 |
520 | =over 4 |
550 | |
521 | |
551 | =item Coro::nready |
522 | =item Coro::nready |
552 | |
523 | |
… | |
… | |
632 | # return immediately and can be reused) and because we cannot cede |
603 | # return immediately and can be reused) and because we cannot cede |
633 | # inside an event callback. |
604 | # inside an event callback. |
634 | our $unblock_scheduler = new Coro sub { |
605 | our $unblock_scheduler = new Coro sub { |
635 | while () { |
606 | while () { |
636 | while (my $cb = pop @unblock_queue) { |
607 | while (my $cb = pop @unblock_queue) { |
637 | # this is an inlined copy of async_pool |
608 | &async_pool (@$cb); |
638 | my $coro = (pop @async_pool) || new Coro \&pool_handler; |
|
|
639 | |
609 | |
640 | $coro->{_invoke} = $cb; |
|
|
641 | $coro->ready; |
|
|
642 | cede; # for short-lived callbacks, this reduces pressure on the coro pool |
610 | # for short-lived callbacks, this reduces pressure on the coro pool |
|
|
611 | # as the chance is very high that the async_poll coro will be back |
|
|
612 | # in the idle state when cede returns |
|
|
613 | cede; |
643 | } |
614 | } |
644 | schedule; # sleep well |
615 | schedule; # sleep well |
645 | } |
616 | } |
646 | }; |
617 | }; |
647 | $unblock_scheduler->desc ("[unblock_sub scheduler]"); |
618 | $unblock_scheduler->{desc} = "[unblock_sub scheduler]"; |
648 | |
619 | |
649 | sub unblock_sub(&) { |
620 | sub unblock_sub(&) { |
650 | my $cb = shift; |
621 | my $cb = shift; |
651 | |
622 | |
652 | sub { |
623 | sub { |
653 | unshift @unblock_queue, [$cb, @_]; |
624 | unshift @unblock_queue, [$cb, @_]; |
654 | $unblock_scheduler->ready; |
625 | $unblock_scheduler->ready; |
655 | } |
626 | } |
656 | } |
627 | } |
657 | |
628 | |
|
|
629 | =item $cb = Coro::rouse_cb |
|
|
630 | |
|
|
631 | Create and return a "rouse callback". That's a code reference that, when |
|
|
632 | called, will save its arguments and notify the owner coroutine of the |
|
|
633 | callback. |
|
|
634 | |
|
|
635 | See the next function. |
|
|
636 | |
|
|
637 | =item @args = Coro::rouse_wait [$cb] |
|
|
638 | |
|
|
639 | Wait for the specified rouse callback (or the last one tht was created in |
|
|
640 | this coroutine). |
|
|
641 | |
|
|
642 | As soon as the callback is invoked (or when the calback was invoked before |
|
|
643 | C<rouse_wait>), it will return a copy of the arguments originally passed |
|
|
644 | to the rouse callback. |
|
|
645 | |
|
|
646 | See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example. |
|
|
647 | |
658 | =back |
648 | =back |
659 | |
649 | |
660 | =cut |
650 | =cut |
661 | |
651 | |
662 | 1; |
652 | 1; |
663 | |
653 | |
|
|
654 | =head1 HOW TO WAIT FOR A CALLBACK |
|
|
655 | |
|
|
656 | It is very common for a coroutine to wait for some callback to be |
|
|
657 | called. This occurs naturally when you use coroutines in an otherwise |
|
|
658 | event-based program, or when you use event-based libraries. |
|
|
659 | |
|
|
660 | These typically register a callback for some event, and call that callback |
|
|
661 | when the event occured. In a coroutine, however, you typically want to |
|
|
662 | just wait for the event, simplyifying things. |
|
|
663 | |
|
|
664 | For example C<< AnyEvent->child >> registers a callback to be called when |
|
|
665 | a specific child has exited: |
|
|
666 | |
|
|
667 | my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... }); |
|
|
668 | |
|
|
669 | But from withina coroutine, you often just want to write this: |
|
|
670 | |
|
|
671 | my $status = wait_for_child $pid; |
|
|
672 | |
|
|
673 | Coro offers two functions specifically designed to make this easy, |
|
|
674 | C<Coro::rouse_cb> and C<Coro::rouse_wait>. |
|
|
675 | |
|
|
676 | The first function, C<rouse_cb>, generates and returns a callback that, |
|
|
677 | when invoked, will save it's arguments and notify the coroutine that |
|
|
678 | created the callback. |
|
|
679 | |
|
|
680 | The second function, C<rouse_wait>, waits for the callback to be called |
|
|
681 | (by calling C<schedule> to go to sleep) and returns the arguments |
|
|
682 | originally passed to the callback. |
|
|
683 | |
|
|
684 | Using these functions, it becomes easy to write the C<wait_for_child> |
|
|
685 | function mentioned above: |
|
|
686 | |
|
|
687 | sub wait_for_child($) { |
|
|
688 | my ($pid) = @_; |
|
|
689 | |
|
|
690 | my $watcher = AnyEvent->child (pid => $pid, cb => Coro::rouse_cb); |
|
|
691 | |
|
|
692 | my ($rpid, $rstatus) = Coro::rouse_wait; |
|
|
693 | $rstatus |
|
|
694 | } |
|
|
695 | |
|
|
696 | In the case where C<rouse_cb> and C<rouse_wait> are not flexible enough, |
|
|
697 | you can roll your own, using C<schedule>: |
|
|
698 | |
|
|
699 | sub wait_for_child($) { |
|
|
700 | my ($pid) = @_; |
|
|
701 | |
|
|
702 | # store the current coroutine in $current, |
|
|
703 | # and provide result variables for the closure passed to ->child |
|
|
704 | my $current = $Coro::current; |
|
|
705 | my ($done, $rstatus); |
|
|
706 | |
|
|
707 | # pass a closure to ->child |
|
|
708 | my $watcher = AnyEvent->child (pid => $pid, cb => sub { |
|
|
709 | $rstatus = $_[1]; # remember rstatus |
|
|
710 | $done = 1; # mark $rstatus as valud |
|
|
711 | }); |
|
|
712 | |
|
|
713 | # wait until the closure has been called |
|
|
714 | schedule while !$done; |
|
|
715 | |
|
|
716 | $rstatus |
|
|
717 | } |
|
|
718 | |
|
|
719 | |
664 | =head1 BUGS/LIMITATIONS |
720 | =head1 BUGS/LIMITATIONS |
|
|
721 | |
|
|
722 | =over 4 |
|
|
723 | |
|
|
724 | =item fork with pthread backend |
|
|
725 | |
|
|
726 | When Coro is compiled using the pthread backend (which isn't recommended |
|
|
727 | but required on many BSDs as their libcs are completely broken), then |
|
|
728 | coroutines will not survive a fork. There is no known workaround except to |
|
|
729 | fix your libc and use a saner backend. |
|
|
730 | |
|
|
731 | =item perl process emulation ("threads") |
665 | |
732 | |
666 | This module is not perl-pseudo-thread-safe. You should only ever use this |
733 | This module is not perl-pseudo-thread-safe. You should only ever use this |
667 | module from the same thread (this requirement might be removed in the |
734 | module from the same thread (this requirement might be removed in the |
668 | future to allow per-thread schedulers, but Coro::State does not yet allow |
735 | future to allow per-thread schedulers, but Coro::State does not yet allow |
669 | this). I recommend disabling thread support and using processes, as this |
736 | this). I recommend disabling thread support and using processes, as having |
670 | is much faster and uses less memory. |
737 | the windows process emulation enabled under unix roughly halves perl |
|
|
738 | performance, even when not used. |
|
|
739 | |
|
|
740 | =item coroutine switching not signal safe |
|
|
741 | |
|
|
742 | You must not switch to another coroutine from within a signal handler |
|
|
743 | (only relevant with %SIG - most event libraries provide safe signals). |
|
|
744 | |
|
|
745 | That means you I<MUST NOT> call any function that might "block" the |
|
|
746 | current coroutine - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or |
|
|
747 | anything that calls those. Everything else, including calling C<ready>, |
|
|
748 | works. |
|
|
749 | |
|
|
750 | =back |
|
|
751 | |
671 | |
752 | |
672 | =head1 SEE ALSO |
753 | =head1 SEE ALSO |
673 | |
754 | |
674 | Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>. |
755 | Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>. |
675 | |
756 | |