… | |
… | |
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 |
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25 | machines. The specific flavor of coroutine used in this module also |
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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 | |
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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). |
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34 | |
26 | In this module, coroutines are defined as "callchain + lexical variables |
35 | In this module, coroutines are defined as "callchain + lexical variables + |
27 | + @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own |
36 | @_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain, |
28 | 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 |
29 | important global variables. |
38 | variables. |
30 | |
39 | |
31 | =cut |
40 | =cut |
32 | |
41 | |
33 | package Coro; |
42 | package Coro; |
34 | |
43 | |
… | |
… | |
41 | |
50 | |
42 | our $idle; # idle handler |
51 | our $idle; # idle handler |
43 | our $main; # main coroutine |
52 | our $main; # main coroutine |
44 | our $current; # current coroutine |
53 | our $current; # current coroutine |
45 | |
54 | |
46 | our $VERSION = '2.5'; |
55 | our $VERSION = '3.8'; |
47 | |
56 | |
48 | our @EXPORT = qw(async cede schedule terminate current); |
57 | our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); |
49 | our %EXPORT_TAGS = ( |
58 | our %EXPORT_TAGS = ( |
50 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
59 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
51 | ); |
60 | ); |
52 | our @EXPORT_OK = @{$EXPORT_TAGS{prio}}; |
61 | our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready)); |
53 | |
62 | |
54 | { |
63 | { |
55 | my @async; |
64 | my @async; |
56 | my $init; |
65 | my $init; |
57 | |
66 | |
58 | # this way of handling attributes simply is NOT scalable ;() |
67 | # this way of handling attributes simply is NOT scalable ;() |
59 | sub import { |
68 | sub import { |
60 | no strict 'refs'; |
69 | no strict 'refs'; |
61 | |
70 | |
62 | Coro->export_to_level(1, @_); |
71 | Coro->export_to_level (1, @_); |
63 | |
72 | |
64 | my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE}; |
73 | my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE}; |
65 | *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub { |
74 | *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub { |
66 | my ($package, $ref) = (shift, shift); |
75 | my ($package, $ref) = (shift, shift); |
67 | my @attrs; |
76 | my @attrs; |
… | |
… | |
99 | |
108 | |
100 | The current coroutine (the last coroutine switched to). The initial value |
109 | The current coroutine (the last coroutine switched to). The initial value |
101 | is C<$main> (of course). |
110 | is C<$main> (of course). |
102 | |
111 | |
103 | This variable is B<strictly> I<read-only>. It is provided for performance |
112 | This variable is B<strictly> I<read-only>. It is provided for performance |
104 | reasons. If performance is not essentiel you are encouraged to use the |
113 | reasons. If performance is not essential you are encouraged to use the |
105 | C<Coro::current> function instead. |
114 | C<Coro::current> function instead. |
106 | |
115 | |
107 | =cut |
116 | =cut |
108 | |
117 | |
|
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118 | $main->{desc} = "[main::]"; |
|
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119 | |
109 | # maybe some other module used Coro::Specific before... |
120 | # maybe some other module used Coro::Specific before... |
110 | if ($current) { |
|
|
111 | $main->{specific} = $current->{specific}; |
121 | $main->{specific} = $current->{specific} |
112 | } |
122 | if $current; |
113 | |
123 | |
114 | $current = $main; |
124 | _set_current $main; |
115 | |
125 | |
116 | sub current() { $current } |
126 | sub current() { $current } |
117 | |
127 | |
118 | =item $idle |
128 | =item $idle |
119 | |
129 | |
120 | A callback that is called whenever the scheduler finds no ready coroutines |
130 | A callback that is called whenever the scheduler finds no ready coroutines |
121 | to run. The default implementation prints "FATAL: deadlock detected" and |
131 | to run. The default implementation prints "FATAL: deadlock detected" and |
122 | exits. |
132 | exits, because the program has no other way to continue. |
123 | |
133 | |
124 | This hook is overwritten by modules such as C<Coro::Timer> and |
134 | This hook is overwritten by modules such as C<Coro::Timer> and |
125 | C<Coro::Event> to wait on an external event that hopefully wakes up some |
135 | C<Coro::Event> to wait on an external event that hopefully wake up a |
126 | coroutine. |
136 | coroutine so the scheduler can run it. |
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137 | |
|
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138 | Please note that if your callback recursively invokes perl (e.g. for event |
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139 | handlers), then it must be prepared to be called recursively. |
127 | |
140 | |
128 | =cut |
141 | =cut |
129 | |
142 | |
130 | $idle = sub { |
143 | $idle = sub { |
131 | print STDERR "FATAL: deadlock detected\n"; |
144 | require Carp; |
132 | exit (51); |
145 | Carp::croak ("FATAL: deadlock detected"); |
133 | }; |
146 | }; |
|
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147 | |
|
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148 | sub _cancel { |
|
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149 | my ($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->{destroy_cb}) || []}; |
|
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158 | } |
|
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159 | |
|
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160 | sub _do_trace { |
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161 | $current->{_trace_cb}->(); |
|
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162 | } |
134 | |
163 | |
135 | # this coroutine is necessary because a coroutine |
164 | # this coroutine is necessary because a coroutine |
136 | # cannot destroy itself. |
165 | # cannot destroy itself. |
137 | my @destroy; |
166 | my @destroy; |
138 | my $manager; |
167 | my $manager; |
|
|
168 | |
139 | $manager = new Coro sub { |
169 | $manager = new Coro sub { |
140 | while () { |
170 | while () { |
141 | # by overwriting the state object with the manager we destroy it |
171 | (shift @destroy)->_cancel |
142 | # while still being able to schedule this coroutine (in case it has |
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143 | # been readied multiple times. this is harmless since the manager |
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144 | # can be called as many times as neccessary and will always |
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145 | # remove itself from the runqueue |
|
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146 | while (@destroy) { |
172 | while @destroy; |
147 | my $coro = pop @destroy; |
|
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148 | $coro->{status} ||= []; |
|
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149 | $_->ready for @{delete $coro->{join} || []}; |
|
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150 | |
173 | |
151 | # the next line destroys the coro state, but keeps the |
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152 | # process itself intact (we basically make it a zombie |
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153 | # process that always runs the manager thread, so it's possible |
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154 | # to transfer() to this process). |
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155 | $coro->_clone_state_from ($manager); |
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156 | } |
|
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157 | &schedule; |
174 | &schedule; |
158 | } |
175 | } |
159 | }; |
176 | }; |
|
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177 | $manager->desc ("[coro manager]"); |
|
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178 | $manager->prio (PRIO_MAX); |
160 | |
179 | |
161 | # static methods. not really. |
180 | # static methods. not really. |
162 | |
181 | |
163 | =back |
182 | =back |
164 | |
183 | |
165 | =head2 STATIC METHODS |
184 | =head2 STATIC METHODS |
166 | |
185 | |
167 | Static methods are actually functions that operate on the current process only. |
186 | Static methods are actually functions that operate on the current coroutine only. |
168 | |
187 | |
169 | =over 4 |
188 | =over 4 |
170 | |
189 | |
171 | =item async { ... } [@args...] |
190 | =item async { ... } [@args...] |
172 | |
191 | |
173 | Create a new asynchronous process and return it's process object |
192 | Create a new asynchronous coroutine and return it's coroutine object |
174 | (usually unused). When the sub returns the new process is automatically |
193 | (usually unused). When the sub returns the new coroutine is automatically |
175 | terminated. |
194 | terminated. |
176 | |
195 | |
177 | When the coroutine dies, the program will exit, just as in the main |
196 | Calling C<exit> in a coroutine will do the same as calling exit outside |
178 | program. |
197 | the coroutine. Likewise, when the coroutine dies, the program will exit, |
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198 | just as it would in the main program. |
179 | |
199 | |
180 | # create a new coroutine that just prints its arguments |
200 | # create a new coroutine that just prints its arguments |
181 | async { |
201 | async { |
182 | print "@_\n"; |
202 | print "@_\n"; |
183 | } 1,2,3,4; |
203 | } 1,2,3,4; |
184 | |
204 | |
185 | =cut |
205 | =cut |
186 | |
206 | |
187 | sub async(&@) { |
207 | sub async(&@) { |
188 | my $pid = new Coro @_; |
208 | my $coro = new Coro @_; |
189 | $pid->ready; |
209 | $coro->ready; |
190 | $pid |
210 | $coro |
|
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211 | } |
|
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212 | |
|
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213 | =item async_pool { ... } [@args...] |
|
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214 | |
|
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215 | Similar to C<async>, but uses a coroutine pool, so you should not call |
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216 | terminate or join (although you are allowed to), and you get a coroutine |
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217 | that might have executed other code already (which can be good or bad :). |
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218 | |
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219 | Also, the block is executed in an C<eval> context and a warning will be |
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220 | issued in case of an exception instead of terminating the program, as |
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221 | C<async> does. As the coroutine is being reused, stuff like C<on_destroy> |
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222 | will not work in the expected way, unless you call terminate or cancel, |
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223 | which somehow defeats the purpose of pooling. |
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224 | |
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225 | The priority will be reset to C<0> after each job, otherwise the coroutine |
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226 | will be re-used "as-is". |
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227 | |
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228 | The pool size is limited to 8 idle coroutines (this can be adjusted by |
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229 | changing $Coro::POOL_SIZE), and there can be as many non-idle coros as |
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230 | required. |
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231 | |
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232 | If you are concerned about pooled coroutines growing a lot because a |
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233 | single C<async_pool> used a lot of stackspace you can e.g. C<async_pool |
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234 | { terminate }> once per second or so to slowly replenish the pool. In |
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235 | addition to that, when the stacks used by a handler grows larger than 16kb |
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236 | (adjustable with $Coro::POOL_RSS) it will also exit. |
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237 | |
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238 | =cut |
|
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239 | |
|
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240 | our $POOL_SIZE = 8; |
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241 | our $POOL_RSS = 16 * 1024; |
|
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242 | our @async_pool; |
|
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243 | |
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244 | sub pool_handler { |
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245 | my $cb; |
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246 | |
|
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247 | while () { |
|
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248 | eval { |
|
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249 | while () { |
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250 | _pool_1 $cb; |
|
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251 | &$cb; |
|
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252 | _pool_2 $cb; |
|
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253 | &schedule; |
|
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254 | } |
|
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255 | }; |
|
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256 | |
|
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257 | last if $@ eq "\3terminate\2\n"; |
|
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258 | warn $@ if $@; |
|
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259 | } |
|
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260 | } |
|
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261 | |
|
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262 | sub async_pool(&@) { |
|
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263 | # this is also inlined into the unlock_scheduler |
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264 | my $coro = (pop @async_pool) || new Coro \&pool_handler; |
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265 | |
|
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266 | $coro->{_invoke} = [@_]; |
|
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267 | $coro->ready; |
|
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268 | |
|
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269 | $coro |
191 | } |
270 | } |
192 | |
271 | |
193 | =item schedule |
272 | =item schedule |
194 | |
273 | |
195 | 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 |
196 | 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 |
197 | never be called again. |
276 | never be called again unless something else (e.g. an event handler) calls |
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277 | ready. |
198 | |
278 | |
199 | =cut |
279 | The canonical way to wait on external events is this: |
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280 | |
|
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281 | { |
|
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282 | # remember current coroutine |
|
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283 | my $current = $Coro::current; |
|
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284 | |
|
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285 | # register a hypothetical event handler |
|
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286 | on_event_invoke sub { |
|
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287 | # wake up sleeping coroutine |
|
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288 | $current->ready; |
|
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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. |
|
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295 | Coro::schedule while $current; |
|
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296 | } |
200 | |
297 | |
201 | =item cede |
298 | =item cede |
202 | |
299 | |
203 | "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 |
204 | 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 |
205 | current "timeslice" to other coroutines of the same or higher priority. |
302 | current "timeslice" to other coroutines of the same or higher priority. |
206 | |
303 | |
207 | =cut |
304 | Returns true if at least one coroutine switch has happened. |
|
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305 | |
|
|
306 | =item Coro::cede_notself |
|
|
307 | |
|
|
308 | Works like cede, but is not exported by default and will cede to any |
|
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309 | coroutine, regardless of priority, once. |
|
|
310 | |
|
|
311 | Returns true if at least one coroutine switch has happened. |
208 | |
312 | |
209 | =item terminate [arg...] |
313 | =item terminate [arg...] |
210 | |
314 | |
211 | Terminates the current process with the given status values (see L<cancel>). |
315 | Terminates the current coroutine with the given status values (see L<cancel>). |
212 | |
316 | |
213 | =cut |
317 | =cut |
214 | |
318 | |
215 | sub terminate { |
319 | sub terminate { |
216 | $current->cancel (@_); |
320 | $current->cancel (@_); |
… | |
… | |
218 | |
322 | |
219 | =back |
323 | =back |
220 | |
324 | |
221 | # dynamic methods |
325 | # dynamic methods |
222 | |
326 | |
223 | =head2 PROCESS METHODS |
327 | =head2 COROUTINE METHODS |
224 | |
328 | |
225 | These are the methods you can call on process objects. |
329 | These are the methods you can call on coroutine objects. |
226 | |
330 | |
227 | =over 4 |
331 | =over 4 |
228 | |
332 | |
229 | =item new Coro \&sub [, @args...] |
333 | =item new Coro \&sub [, @args...] |
230 | |
334 | |
231 | 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 |
232 | automatically terminates as if C<terminate> with the returned values were |
336 | automatically terminates as if C<terminate> with the returned values were |
233 | called. To make the process run you must first put it into the ready queue |
337 | called. To make the coroutine run you must first put it into the ready queue |
234 | by calling the ready method. |
338 | by calling the ready method. |
235 | |
339 | |
236 | =cut |
340 | See C<async> for additional discussion. |
237 | |
341 | |
|
|
342 | =cut |
|
|
343 | |
238 | sub _new_coro { |
344 | sub _run_coro { |
239 | $current->_clear_idle_sp; # set the idle sp on the following cede |
|
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240 | _set_cede_self; # ensures that cede cede's us first |
|
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241 | cede; |
|
|
242 | terminate &{+shift}; |
345 | terminate &{+shift}; |
243 | } |
346 | } |
244 | |
347 | |
245 | sub new { |
348 | sub new { |
246 | my $class = shift; |
349 | my $class = shift; |
247 | |
350 | |
248 | $class->SUPER::new (\&_new_coro, @_) |
351 | $class->SUPER::new (\&_run_coro, @_) |
249 | } |
352 | } |
250 | |
353 | |
251 | =item $process->ready |
354 | =item $success = $coroutine->ready |
252 | |
355 | |
253 | Put the given process into the ready queue. |
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. |
254 | |
359 | |
255 | =cut |
360 | =item $is_ready = $coroutine->is_ready |
256 | |
361 | |
|
|
362 | Return wether the coroutine is currently the ready queue or not, |
|
|
363 | |
257 | =item $process->cancel (arg...) |
364 | =item $coroutine->cancel (arg...) |
258 | |
365 | |
259 | Terminates the given process and makes it return the given arguments as |
366 | Terminates the given coroutine and makes it return the given arguments as |
260 | status (default: the empty list). |
367 | status (default: the empty list). Never returns if the coroutine is the |
|
|
368 | current coroutine. |
261 | |
369 | |
262 | =cut |
370 | =cut |
263 | |
371 | |
264 | sub cancel { |
372 | sub cancel { |
265 | my $self = shift; |
373 | my $self = shift; |
266 | $self->{status} = [@_]; |
374 | $self->{status} = [@_]; |
|
|
375 | |
|
|
376 | if ($current == $self) { |
267 | push @destroy, $self; |
377 | push @destroy, $self; |
268 | $manager->ready; |
378 | $manager->ready; |
269 | &schedule if $current == $self; |
379 | &schedule while 1; |
|
|
380 | } else { |
|
|
381 | $self->_cancel; |
|
|
382 | } |
270 | } |
383 | } |
271 | |
384 | |
272 | =item $process->join |
385 | =item $coroutine->join |
273 | |
386 | |
274 | Wait until the coroutine terminates and return any values given to the |
387 | Wait until the coroutine terminates and return any values given to the |
275 | C<terminate> or C<cancel> functions. C<join> can be called multiple times |
388 | C<terminate> or C<cancel> functions. C<join> can be called multiple times |
276 | from multiple processes. |
389 | from multiple coroutine. |
277 | |
390 | |
278 | =cut |
391 | =cut |
279 | |
392 | |
280 | sub join { |
393 | sub join { |
281 | my $self = shift; |
394 | my $self = shift; |
|
|
395 | |
282 | unless ($self->{status}) { |
396 | unless ($self->{status}) { |
283 | push @{$self->{join}}, $current; |
397 | my $current = $current; |
284 | &schedule; |
398 | |
|
|
399 | push @{$self->{destroy_cb}}, sub { |
|
|
400 | $current->ready; |
|
|
401 | undef $current; |
|
|
402 | }; |
|
|
403 | |
|
|
404 | &schedule while $current; |
285 | } |
405 | } |
|
|
406 | |
286 | wantarray ? @{$self->{status}} : $self->{status}[0]; |
407 | wantarray ? @{$self->{status}} : $self->{status}[0]; |
287 | } |
408 | } |
288 | |
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 | |
289 | =item $oldprio = $process->prio ($newprio) |
424 | =item $oldprio = $coroutine->prio ($newprio) |
290 | |
425 | |
291 | Sets (or gets, if the argument is missing) the priority of the |
426 | Sets (or gets, if the argument is missing) the priority of the |
292 | process. Higher priority processes get run before lower priority |
427 | coroutine. Higher priority coroutines get run before lower priority |
293 | processes. Priorities are small signed integers (currently -4 .. +3), |
428 | coroutines. Priorities are small signed integers (currently -4 .. +3), |
294 | that you can refer to using PRIO_xxx constants (use the import tag :prio |
429 | that you can refer to using PRIO_xxx constants (use the import tag :prio |
295 | to get then): |
430 | to get then): |
296 | |
431 | |
297 | PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN |
432 | PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN |
298 | 3 > 1 > 0 > -1 > -3 > -4 |
433 | 3 > 1 > 0 > -1 > -3 > -4 |
… | |
… | |
301 | current->prio(PRIO_HIGH); |
436 | current->prio(PRIO_HIGH); |
302 | |
437 | |
303 | The idle coroutine ($Coro::idle) always has a lower priority than any |
438 | The idle coroutine ($Coro::idle) always has a lower priority than any |
304 | existing coroutine. |
439 | existing coroutine. |
305 | |
440 | |
306 | Changing the priority of the current process will take effect immediately, |
441 | Changing the priority of the current coroutine will take effect immediately, |
307 | but changing the priority of processes in the ready queue (but not |
442 | but changing the priority of coroutines in the ready queue (but not |
308 | running) will only take effect after the next schedule (of that |
443 | running) will only take effect after the next schedule (of that |
309 | process). This is a bug that will be fixed in some future version. |
444 | coroutine). This is a bug that will be fixed in some future version. |
310 | |
445 | |
311 | =item $newprio = $process->nice ($change) |
446 | =item $newprio = $coroutine->nice ($change) |
312 | |
447 | |
313 | Similar to C<prio>, but subtract the given value from the priority (i.e. |
448 | Similar to C<prio>, but subtract the given value from the priority (i.e. |
314 | higher values mean lower priority, just as in unix). |
449 | higher values mean lower priority, just as in unix). |
315 | |
450 | |
316 | =item $olddesc = $process->desc ($newdesc) |
451 | =item $olddesc = $coroutine->desc ($newdesc) |
317 | |
452 | |
318 | Sets (or gets in case the argument is missing) the description for this |
453 | Sets (or gets in case the argument is missing) the description for this |
319 | process. This is just a free-form string you can associate with a process. |
454 | coroutine. This is just a free-form string you can associate with a coroutine. |
320 | |
455 | |
321 | =cut |
456 | =cut |
322 | |
457 | |
323 | sub desc { |
458 | sub desc { |
324 | my $old = $_[0]{desc}; |
459 | my $old = $_[0]{desc}; |
… | |
… | |
326 | $old; |
461 | $old; |
327 | } |
462 | } |
328 | |
463 | |
329 | =back |
464 | =back |
330 | |
465 | |
|
|
466 | =head2 GLOBAL FUNCTIONS |
|
|
467 | |
|
|
468 | =over 4 |
|
|
469 | |
|
|
470 | =item Coro::nready |
|
|
471 | |
|
|
472 | Returns the number of coroutines that are currently in the ready state, |
|
|
473 | i.e. that can be switched to. The value C<0> means that the only runnable |
|
|
474 | coroutine is the currently running one, so C<cede> would have no effect, |
|
|
475 | and C<schedule> would cause a deadlock unless there is an idle handler |
|
|
476 | that wakes up some coroutines. |
|
|
477 | |
|
|
478 | =item my $guard = Coro::guard { ... } |
|
|
479 | |
|
|
480 | This creates and returns a guard object. Nothing happens until the object |
|
|
481 | gets destroyed, in which case the codeblock given as argument will be |
|
|
482 | executed. This is useful to free locks or other resources in case of a |
|
|
483 | runtime error or when the coroutine gets canceled, as in both cases the |
|
|
484 | guard block will be executed. The guard object supports only one method, |
|
|
485 | C<< ->cancel >>, which will keep the codeblock from being executed. |
|
|
486 | |
|
|
487 | Example: set some flag and clear it again when the coroutine gets canceled |
|
|
488 | or the function returns: |
|
|
489 | |
|
|
490 | sub do_something { |
|
|
491 | my $guard = Coro::guard { $busy = 0 }; |
|
|
492 | $busy = 1; |
|
|
493 | |
|
|
494 | # do something that requires $busy to be true |
|
|
495 | } |
|
|
496 | |
|
|
497 | =cut |
|
|
498 | |
|
|
499 | sub guard(&) { |
|
|
500 | bless \(my $cb = $_[0]), "Coro::guard" |
|
|
501 | } |
|
|
502 | |
|
|
503 | sub Coro::guard::cancel { |
|
|
504 | ${$_[0]} = sub { }; |
|
|
505 | } |
|
|
506 | |
|
|
507 | sub Coro::guard::DESTROY { |
|
|
508 | ${$_[0]}->(); |
|
|
509 | } |
|
|
510 | |
|
|
511 | |
|
|
512 | =item unblock_sub { ... } |
|
|
513 | |
|
|
514 | This utility function takes a BLOCK or code reference and "unblocks" it, |
|
|
515 | returning the new coderef. This means that the new coderef will return |
|
|
516 | immediately without blocking, returning nothing, while the original code |
|
|
517 | ref will be called (with parameters) from within its own coroutine. |
|
|
518 | |
|
|
519 | The reason this function exists is that many event libraries (such as the |
|
|
520 | venerable L<Event|Event> module) are not coroutine-safe (a weaker form |
|
|
521 | of thread-safety). This means you must not block within event callbacks, |
|
|
522 | otherwise you might suffer from crashes or worse. |
|
|
523 | |
|
|
524 | This function allows your callbacks to block by executing them in another |
|
|
525 | coroutine where it is safe to block. One example where blocking is handy |
|
|
526 | is when you use the L<Coro::AIO|Coro::AIO> functions to save results to |
|
|
527 | disk. |
|
|
528 | |
|
|
529 | In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when |
|
|
530 | creating event callbacks that want to block. |
|
|
531 | |
|
|
532 | =cut |
|
|
533 | |
|
|
534 | our @unblock_queue; |
|
|
535 | |
|
|
536 | # we create a special coro because we want to cede, |
|
|
537 | # to reduce pressure on the coro pool (because most callbacks |
|
|
538 | # return immediately and can be reused) and because we cannot cede |
|
|
539 | # inside an event callback. |
|
|
540 | our $unblock_scheduler = new Coro sub { |
|
|
541 | while () { |
|
|
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; |
|
|
547 | $coro->ready; |
|
|
548 | cede; # for short-lived callbacks, this reduces pressure on the coro pool |
|
|
549 | } |
|
|
550 | schedule; # sleep well |
|
|
551 | } |
|
|
552 | }; |
|
|
553 | $unblock_scheduler->desc ("[unblock_sub scheduler]"); |
|
|
554 | |
|
|
555 | sub unblock_sub(&) { |
|
|
556 | my $cb = shift; |
|
|
557 | |
|
|
558 | sub { |
|
|
559 | unshift @unblock_queue, [$cb, @_]; |
|
|
560 | $unblock_scheduler->ready; |
|
|
561 | } |
|
|
562 | } |
|
|
563 | |
|
|
564 | =back |
|
|
565 | |
331 | =cut |
566 | =cut |
332 | |
567 | |
333 | 1; |
568 | 1; |
334 | |
569 | |
335 | =head1 BUGS/LIMITATIONS |
570 | =head1 BUGS/LIMITATIONS |
336 | |
571 | |
337 | - you must make very sure that no coro is still active on global |
572 | - you must make very sure that no coro is still active on global |
338 | destruction. very bad things might happen otherwise (usually segfaults). |
573 | destruction. very bad things might happen otherwise (usually segfaults). |
339 | |
574 | |
340 | - this module is not thread-safe. You should only ever use this module |
575 | - this module is not thread-safe. You should only ever use this module |
341 | from the same thread (this requirement might be losened in the future |
576 | from the same thread (this requirement might be loosened in the future |
342 | to allow per-thread schedulers, but Coro::State does not yet allow |
577 | to allow per-thread schedulers, but Coro::State does not yet allow |
343 | this). |
578 | this). |
344 | |
579 | |
345 | =head1 SEE ALSO |
580 | =head1 SEE ALSO |
346 | |
581 | |