… | |
… | |
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 use din this module also |
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26 | guarentees 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 | @_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain, |
28 | callchain, it's own set of lexicals and it's own set of perl's most |
37 | its own set of lexicals and its own set of perls most important global |
29 | important global variables. |
38 | variables. |
30 | |
39 | |
31 | =cut |
40 | =cut |
32 | |
41 | |
33 | package Coro; |
42 | package Coro; |
34 | |
43 | |
35 | BEGIN { eval { require warnings } && warnings->unimport ("uninitialized") } |
44 | use strict; |
|
|
45 | no warnings "uninitialized"; |
36 | |
46 | |
37 | use Coro::State; |
47 | use Coro::State; |
38 | |
48 | |
39 | use vars qw($idle $main $current); |
49 | use base qw(Coro::State Exporter); |
40 | |
50 | |
41 | use base Exporter; |
51 | our $idle; # idle handler |
|
|
52 | our $main; # main coroutine |
|
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53 | our $current; # current coroutine |
42 | |
54 | |
43 | $VERSION = 1.1; |
55 | our $VERSION = '3.56'; |
44 | |
56 | |
45 | @EXPORT = qw(async cede schedule terminate current); |
57 | our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); |
46 | %EXPORT_TAGS = ( |
58 | our %EXPORT_TAGS = ( |
47 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
59 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
48 | ); |
60 | ); |
49 | @EXPORT_OK = @{$EXPORT_TAGS{prio}}; |
61 | our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready)); |
50 | |
62 | |
51 | { |
63 | { |
52 | my @async; |
64 | my @async; |
53 | my $init; |
65 | my $init; |
54 | |
66 | |
55 | # this way of handling attributes simply is NOT scalable ;() |
67 | # this way of handling attributes simply is NOT scalable ;() |
56 | sub import { |
68 | sub import { |
|
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69 | no strict 'refs'; |
|
|
70 | |
57 | Coro->export_to_level(1, @_); |
71 | Coro->export_to_level (1, @_); |
|
|
72 | |
58 | my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE}; |
73 | my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE}; |
59 | *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub { |
74 | *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub { |
60 | my ($package, $ref) = (shift, shift); |
75 | my ($package, $ref) = (shift, shift); |
61 | my @attrs; |
76 | my @attrs; |
62 | for (@_) { |
77 | for (@_) { |
… | |
… | |
89 | |
104 | |
90 | $main = new Coro; |
105 | $main = new Coro; |
91 | |
106 | |
92 | =item $current (or as function: current) |
107 | =item $current (or as function: current) |
93 | |
108 | |
94 | The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course). |
109 | The current coroutine (the last coroutine switched to). The initial value |
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110 | is C<$main> (of course). |
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111 | |
|
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112 | This variable is B<strictly> I<read-only>. It is provided for performance |
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113 | reasons. If performance is not essentiel you are encouraged to use the |
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114 | C<Coro::current> function instead. |
95 | |
115 | |
96 | =cut |
116 | =cut |
97 | |
117 | |
98 | # maybe some other module used Coro::Specific before... |
118 | # maybe some other module used Coro::Specific before... |
99 | if ($current) { |
|
|
100 | $main->{specific} = $current->{specific}; |
119 | $main->{specific} = $current->{specific} |
101 | } |
120 | if $current; |
102 | |
121 | |
103 | $current = $main; |
122 | _set_current $main; |
104 | |
123 | |
105 | sub current() { $current } |
124 | sub current() { $current } |
106 | |
125 | |
107 | =item $idle |
126 | =item $idle |
108 | |
127 | |
109 | The coroutine to switch to when no other coroutine is running. The default |
128 | A callback that is called whenever the scheduler finds no ready coroutines |
110 | implementation prints "FATAL: deadlock detected" and exits. |
129 | to run. The default implementation prints "FATAL: deadlock detected" and |
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130 | exits, because the program has no other way to continue. |
111 | |
131 | |
112 | =cut |
132 | This hook is overwritten by modules such as C<Coro::Timer> and |
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133 | C<Coro::Event> to wait on an external event that hopefully wake up a |
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134 | coroutine so the scheduler can run it. |
113 | |
135 | |
114 | # should be done using priorities :( |
136 | Please note that if your callback recursively invokes perl (e.g. for event |
115 | $idle = new Coro sub { |
137 | handlers), then it must be prepared to be called recursively. |
116 | print STDERR "FATAL: deadlock detected\n"; |
138 | |
117 | exit(51); |
139 | =cut |
|
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140 | |
|
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141 | $idle = sub { |
|
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142 | require Carp; |
|
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143 | Carp::croak ("FATAL: deadlock detected"); |
118 | }; |
144 | }; |
|
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145 | |
|
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146 | sub _cancel { |
|
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147 | my ($self) = @_; |
|
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148 | |
|
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149 | # free coroutine data and mark as destructed |
|
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150 | $self->_destroy |
|
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151 | or return; |
|
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152 | |
|
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153 | # call all destruction callbacks |
|
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154 | $_->(@{$self->{status}}) |
|
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155 | for @{(delete $self->{destroy_cb}) || []}; |
|
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156 | } |
119 | |
157 | |
120 | # this coroutine is necessary because a coroutine |
158 | # this coroutine is necessary because a coroutine |
121 | # cannot destroy itself. |
159 | # cannot destroy itself. |
122 | my @destroy; |
160 | my @destroy; |
123 | my $manager; |
161 | my $manager; |
|
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162 | |
124 | $manager = new Coro sub { |
163 | $manager = new Coro sub { |
125 | while () { |
164 | while () { |
126 | # by overwriting the state object with the manager we destroy it |
165 | (shift @destroy)->_cancel |
127 | # while still being able to schedule this coroutine (in case it has |
|
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128 | # been readied multiple times. this is harmless since the manager |
|
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129 | # can be called as many times as neccessary and will always |
|
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130 | # remove itself from the runqueue |
|
|
131 | while (@destroy) { |
166 | while @destroy; |
132 | my $coro = pop @destroy; |
|
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133 | $coro->{status} ||= []; |
|
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134 | $_->ready for @{delete $coro->{join} || []}; |
|
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135 | |
167 | |
136 | # the next line destroys the _coro_state, but keeps the |
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137 | # process itself intact (we basically make it a zombie |
|
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138 | # process that always runs the manager thread, so it's possible |
|
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139 | # to transfer() to this process). |
|
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140 | $coro->{_coro_state} = $manager->{_coro_state}; |
|
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141 | } |
|
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142 | &schedule; |
168 | &schedule; |
143 | } |
169 | } |
144 | }; |
170 | }; |
145 | |
171 | |
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172 | $manager->prio (PRIO_MAX); |
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173 | |
146 | # static methods. not really. |
174 | # static methods. not really. |
147 | |
175 | |
148 | =back |
176 | =back |
149 | |
177 | |
150 | =head2 STATIC METHODS |
178 | =head2 STATIC METHODS |
151 | |
179 | |
152 | Static methods are actually functions that operate on the current process only. |
180 | Static methods are actually functions that operate on the current coroutine only. |
153 | |
181 | |
154 | =over 4 |
182 | =over 4 |
155 | |
183 | |
156 | =item async { ... } [@args...] |
184 | =item async { ... } [@args...] |
157 | |
185 | |
158 | Create a new asynchronous process and return it's process object |
186 | Create a new asynchronous coroutine and return it's coroutine object |
159 | (usually unused). When the sub returns the new process is automatically |
187 | (usually unused). When the sub returns the new coroutine is automatically |
160 | terminated. |
188 | terminated. |
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189 | |
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190 | Calling C<exit> in a coroutine will try to do the same as calling exit |
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191 | outside the coroutine, but this is experimental. It is best not to rely on |
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192 | exit doing any cleanups or even not crashing. |
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193 | |
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194 | When the coroutine dies, the program will exit, just as in the main |
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195 | program. |
161 | |
196 | |
162 | # create a new coroutine that just prints its arguments |
197 | # create a new coroutine that just prints its arguments |
163 | async { |
198 | async { |
164 | print "@_\n"; |
199 | print "@_\n"; |
165 | } 1,2,3,4; |
200 | } 1,2,3,4; |
166 | |
201 | |
167 | =cut |
202 | =cut |
168 | |
203 | |
169 | sub async(&@) { |
204 | sub async(&@) { |
170 | my $pid = new Coro @_; |
205 | my $coro = new Coro @_; |
171 | $manager->ready; # this ensures that the stack is cloned from the manager |
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172 | $pid->ready; |
206 | $coro->ready; |
173 | $pid; |
207 | $coro |
|
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208 | } |
|
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209 | |
|
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210 | =item async_pool { ... } [@args...] |
|
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211 | |
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212 | Similar to C<async>, but uses a coroutine pool, so you should not call |
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213 | terminate or join (although you are allowed to), and you get a coroutine |
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214 | that might have executed other code already (which can be good or bad :). |
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215 | |
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216 | Also, the block is executed in an C<eval> context and a warning will be |
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217 | issued in case of an exception instead of terminating the program, as |
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218 | C<async> does. As the coroutine is being reused, stuff like C<on_destroy> |
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219 | will not work in the expected way, unless you call terminate or cancel, |
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220 | which somehow defeats the purpose of pooling. |
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221 | |
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222 | The priority will be reset to C<0> after each job, otherwise the coroutine |
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223 | will be re-used "as-is". |
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224 | |
|
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225 | The pool size is limited to 8 idle coroutines (this can be adjusted by |
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226 | changing $Coro::POOL_SIZE), and there can be as many non-idle coros as |
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227 | required. |
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228 | |
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229 | If you are concerned about pooled coroutines growing a lot because a |
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230 | single C<async_pool> used a lot of stackspace you can e.g. C<async_pool { |
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231 | terminate }> once per second or so to slowly replenish the pool. |
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232 | |
|
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233 | =cut |
|
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234 | |
|
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235 | our $POOL_SIZE = 8; |
|
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236 | our @pool; |
|
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237 | |
|
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238 | sub pool_handler { |
|
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239 | while () { |
|
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240 | eval { |
|
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241 | my ($cb, @arg) = @{ delete $current->{_invoke} or return }; |
|
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242 | $cb->(@arg); |
|
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243 | }; |
|
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244 | warn $@ if $@; |
|
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245 | |
|
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246 | last if @pool >= $POOL_SIZE; |
|
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247 | push @pool, $current; |
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248 | |
|
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249 | $current->save (Coro::State::SAVE_DEF); |
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250 | $current->prio (0); |
|
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251 | schedule; |
|
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252 | } |
|
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253 | } |
|
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254 | |
|
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255 | sub async_pool(&@) { |
|
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256 | # this is also inlined into the unlock_scheduler |
|
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257 | my $coro = (pop @pool or new Coro \&pool_handler); |
|
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258 | |
|
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259 | $coro->{_invoke} = [@_]; |
|
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260 | $coro->ready; |
|
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261 | |
|
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262 | $coro |
174 | } |
263 | } |
175 | |
264 | |
176 | =item schedule |
265 | =item schedule |
177 | |
266 | |
178 | Calls the scheduler. Please note that the current process will not be put |
267 | Calls the scheduler. Please note that the current coroutine will not be put |
179 | into the ready queue, so calling this function usually means you will |
268 | into the ready queue, so calling this function usually means you will |
180 | never be called again. |
269 | never be called again unless something else (e.g. an event handler) calls |
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270 | ready. |
181 | |
271 | |
182 | =cut |
272 | The canonical way to wait on external events is this: |
|
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273 | |
|
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274 | { |
|
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275 | # remember current coroutine |
|
|
276 | my $current = $Coro::current; |
|
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277 | |
|
|
278 | # register a hypothetical event handler |
|
|
279 | on_event_invoke sub { |
|
|
280 | # wake up sleeping coroutine |
|
|
281 | $current->ready; |
|
|
282 | undef $current; |
|
|
283 | }; |
|
|
284 | |
|
|
285 | # call schedule until event occured. |
|
|
286 | # in case we are woken up for other reasons |
|
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287 | # (current still defined), loop. |
|
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288 | Coro::schedule while $current; |
|
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289 | } |
183 | |
290 | |
184 | =item cede |
291 | =item cede |
185 | |
292 | |
186 | "Cede" to other processes. This function puts the current process into the |
293 | "Cede" to other coroutines. This function puts the current coroutine into the |
187 | ready queue and calls C<schedule>, which has the effect of giving up the |
294 | ready queue and calls C<schedule>, which has the effect of giving up the |
188 | current "timeslice" to other coroutines of the same or higher priority. |
295 | current "timeslice" to other coroutines of the same or higher priority. |
189 | |
296 | |
190 | =cut |
297 | Returns true if at least one coroutine switch has happened. |
|
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298 | |
|
|
299 | =item Coro::cede_notself |
|
|
300 | |
|
|
301 | Works like cede, but is not exported by default and will cede to any |
|
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302 | coroutine, regardless of priority, once. |
|
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303 | |
|
|
304 | Returns true if at least one coroutine switch has happened. |
191 | |
305 | |
192 | =item terminate [arg...] |
306 | =item terminate [arg...] |
193 | |
307 | |
194 | Terminates the current process with the given status values (see L<cancel>). |
308 | Terminates the current coroutine with the given status values (see L<cancel>). |
195 | |
309 | |
196 | =cut |
310 | =cut |
197 | |
311 | |
198 | sub terminate { |
312 | sub terminate { |
199 | $current->cancel (@_); |
313 | $current->cancel (@_); |
… | |
… | |
201 | |
315 | |
202 | =back |
316 | =back |
203 | |
317 | |
204 | # dynamic methods |
318 | # dynamic methods |
205 | |
319 | |
206 | =head2 PROCESS METHODS |
320 | =head2 COROUTINE METHODS |
207 | |
321 | |
208 | These are the methods you can call on process objects. |
322 | These are the methods you can call on coroutine objects. |
209 | |
323 | |
210 | =over 4 |
324 | =over 4 |
211 | |
325 | |
212 | =item new Coro \&sub [, @args...] |
326 | =item new Coro \&sub [, @args...] |
213 | |
327 | |
214 | Create a new process and return it. When the sub returns the process |
328 | Create a new coroutine and return it. When the sub returns the coroutine |
215 | automatically terminates as if C<terminate> with the returned values were |
329 | automatically terminates as if C<terminate> with the returned values were |
216 | called. To make the process run you must first put it into the ready queue |
330 | called. To make the coroutine run you must first put it into the ready queue |
217 | by calling the ready method. |
331 | by calling the ready method. |
218 | |
332 | |
219 | =cut |
333 | See C<async> for additional discussion. |
220 | |
334 | |
|
|
335 | =cut |
|
|
336 | |
221 | sub _newcoro { |
337 | sub _run_coro { |
222 | terminate &{+shift}; |
338 | terminate &{+shift}; |
223 | } |
339 | } |
224 | |
340 | |
225 | sub new { |
341 | sub new { |
226 | my $class = shift; |
342 | my $class = shift; |
227 | bless { |
|
|
228 | _coro_state => (new Coro::State $_[0] && \&_newcoro, @_), |
|
|
229 | }, $class; |
|
|
230 | } |
|
|
231 | |
343 | |
232 | =item $process->ready |
344 | $class->SUPER::new (\&_run_coro, @_) |
|
|
345 | } |
233 | |
346 | |
234 | Put the given process into the ready queue. |
347 | =item $success = $coroutine->ready |
235 | |
348 | |
236 | =cut |
349 | Put the given coroutine into the ready queue (according to it's priority) |
|
|
350 | and return true. If the coroutine is already in the ready queue, do nothing |
|
|
351 | and return false. |
237 | |
352 | |
|
|
353 | =item $is_ready = $coroutine->is_ready |
|
|
354 | |
|
|
355 | Return wether the coroutine is currently the ready queue or not, |
|
|
356 | |
238 | =item $process->cancel (arg...) |
357 | =item $coroutine->cancel (arg...) |
239 | |
358 | |
240 | Temrinates the given process and makes it return the given arguments as |
359 | Terminates the given coroutine and makes it return the given arguments as |
241 | status (default: the empty list). |
360 | status (default: the empty list). Never returns if the coroutine is the |
|
|
361 | current coroutine. |
242 | |
362 | |
243 | =cut |
363 | =cut |
244 | |
364 | |
245 | sub cancel { |
365 | sub cancel { |
246 | my $self = shift; |
366 | my $self = shift; |
247 | $self->{status} = [@_]; |
367 | $self->{status} = [@_]; |
|
|
368 | |
|
|
369 | if ($current == $self) { |
248 | push @destroy, $self; |
370 | push @destroy, $self; |
249 | $manager->ready; |
371 | $manager->ready; |
250 | &schedule if $current == $self; |
372 | &schedule while 1; |
|
|
373 | } else { |
|
|
374 | $self->_cancel; |
|
|
375 | } |
251 | } |
376 | } |
252 | |
377 | |
253 | =item $process->join |
378 | =item $coroutine->join |
254 | |
379 | |
255 | Wait until the coroutine terminates and return any values given to the |
380 | Wait until the coroutine terminates and return any values given to the |
256 | C<terminate> or C<cancel> functions. C<join> can be called multiple times |
381 | C<terminate> or C<cancel> functions. C<join> can be called multiple times |
257 | from multiple processes. |
382 | from multiple coroutine. |
258 | |
383 | |
259 | =cut |
384 | =cut |
260 | |
385 | |
261 | sub join { |
386 | sub join { |
262 | my $self = shift; |
387 | my $self = shift; |
|
|
388 | |
263 | unless ($self->{status}) { |
389 | unless ($self->{status}) { |
264 | push @{$self->{join}}, $current; |
390 | my $current = $current; |
265 | &schedule; |
391 | |
|
|
392 | push @{$self->{destroy_cb}}, sub { |
|
|
393 | $current->ready; |
|
|
394 | undef $current; |
|
|
395 | }; |
|
|
396 | |
|
|
397 | &schedule while $current; |
266 | } |
398 | } |
|
|
399 | |
267 | wantarray ? @{$self->{status}} : $self->{status}[0]; |
400 | wantarray ? @{$self->{status}} : $self->{status}[0]; |
268 | } |
401 | } |
269 | |
402 | |
|
|
403 | =item $coroutine->on_destroy (\&cb) |
|
|
404 | |
|
|
405 | Registers a callback that is called when this coroutine gets destroyed, |
|
|
406 | but before it is joined. The callback gets passed the terminate arguments, |
|
|
407 | if any. |
|
|
408 | |
|
|
409 | =cut |
|
|
410 | |
|
|
411 | sub on_destroy { |
|
|
412 | my ($self, $cb) = @_; |
|
|
413 | |
|
|
414 | push @{ $self->{destroy_cb} }, $cb; |
|
|
415 | } |
|
|
416 | |
270 | =item $oldprio = $process->prio($newprio) |
417 | =item $oldprio = $coroutine->prio ($newprio) |
271 | |
418 | |
272 | Sets (or gets, if the argument is missing) the priority of the |
419 | Sets (or gets, if the argument is missing) the priority of the |
273 | process. Higher priority processes get run before lower priority |
420 | coroutine. Higher priority coroutines get run before lower priority |
274 | processes. Priorities are small signed integers (currently -4 .. +3), |
421 | coroutines. Priorities are small signed integers (currently -4 .. +3), |
275 | that you can refer to using PRIO_xxx constants (use the import tag :prio |
422 | that you can refer to using PRIO_xxx constants (use the import tag :prio |
276 | to get then): |
423 | to get then): |
277 | |
424 | |
278 | PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN |
425 | PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN |
279 | 3 > 1 > 0 > -1 > -3 > -4 |
426 | 3 > 1 > 0 > -1 > -3 > -4 |
… | |
… | |
282 | current->prio(PRIO_HIGH); |
429 | current->prio(PRIO_HIGH); |
283 | |
430 | |
284 | The idle coroutine ($Coro::idle) always has a lower priority than any |
431 | The idle coroutine ($Coro::idle) always has a lower priority than any |
285 | existing coroutine. |
432 | existing coroutine. |
286 | |
433 | |
287 | Changing the priority of the current process will take effect immediately, |
434 | Changing the priority of the current coroutine will take effect immediately, |
288 | but changing the priority of processes in the ready queue (but not |
435 | but changing the priority of coroutines in the ready queue (but not |
289 | running) will only take effect after the next schedule (of that |
436 | running) will only take effect after the next schedule (of that |
290 | process). This is a bug that will be fixed in some future version. |
437 | coroutine). This is a bug that will be fixed in some future version. |
291 | |
438 | |
292 | =cut |
|
|
293 | |
|
|
294 | sub prio { |
|
|
295 | my $old = $_[0]{prio}; |
|
|
296 | $_[0]{prio} = $_[1] if @_ > 1; |
|
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297 | $old; |
|
|
298 | } |
|
|
299 | |
|
|
300 | =item $newprio = $process->nice($change) |
439 | =item $newprio = $coroutine->nice ($change) |
301 | |
440 | |
302 | Similar to C<prio>, but subtract the given value from the priority (i.e. |
441 | Similar to C<prio>, but subtract the given value from the priority (i.e. |
303 | higher values mean lower priority, just as in unix). |
442 | higher values mean lower priority, just as in unix). |
304 | |
443 | |
305 | =cut |
|
|
306 | |
|
|
307 | sub nice { |
|
|
308 | $_[0]{prio} -= $_[1]; |
|
|
309 | } |
|
|
310 | |
|
|
311 | =item $olddesc = $process->desc($newdesc) |
444 | =item $olddesc = $coroutine->desc ($newdesc) |
312 | |
445 | |
313 | Sets (or gets in case the argument is missing) the description for this |
446 | Sets (or gets in case the argument is missing) the description for this |
314 | process. This is just a free-form string you can associate with a process. |
447 | coroutine. This is just a free-form string you can associate with a coroutine. |
315 | |
448 | |
316 | =cut |
449 | =cut |
317 | |
450 | |
318 | sub desc { |
451 | sub desc { |
319 | my $old = $_[0]{desc}; |
452 | my $old = $_[0]{desc}; |
… | |
… | |
321 | $old; |
454 | $old; |
322 | } |
455 | } |
323 | |
456 | |
324 | =back |
457 | =back |
325 | |
458 | |
|
|
459 | =head2 GLOBAL FUNCTIONS |
|
|
460 | |
|
|
461 | =over 4 |
|
|
462 | |
|
|
463 | =item Coro::nready |
|
|
464 | |
|
|
465 | Returns the number of coroutines that are currently in the ready state, |
|
|
466 | i.e. that can be swicthed to. The value C<0> means that the only runnable |
|
|
467 | coroutine is the currently running one, so C<cede> would have no effect, |
|
|
468 | and C<schedule> would cause a deadlock unless there is an idle handler |
|
|
469 | that wakes up some coroutines. |
|
|
470 | |
|
|
471 | =item my $guard = Coro::guard { ... } |
|
|
472 | |
|
|
473 | This creates and returns a guard object. Nothing happens until the object |
|
|
474 | gets destroyed, in which case the codeblock given as argument will be |
|
|
475 | executed. This is useful to free locks or other resources in case of a |
|
|
476 | runtime error or when the coroutine gets canceled, as in both cases the |
|
|
477 | guard block will be executed. The guard object supports only one method, |
|
|
478 | C<< ->cancel >>, which will keep the codeblock from being executed. |
|
|
479 | |
|
|
480 | Example: set some flag and clear it again when the coroutine gets canceled |
|
|
481 | or the function returns: |
|
|
482 | |
|
|
483 | sub do_something { |
|
|
484 | my $guard = Coro::guard { $busy = 0 }; |
|
|
485 | $busy = 1; |
|
|
486 | |
|
|
487 | # do something that requires $busy to be true |
|
|
488 | } |
|
|
489 | |
|
|
490 | =cut |
|
|
491 | |
|
|
492 | sub guard(&) { |
|
|
493 | bless \(my $cb = $_[0]), "Coro::guard" |
|
|
494 | } |
|
|
495 | |
|
|
496 | sub Coro::guard::cancel { |
|
|
497 | ${$_[0]} = sub { }; |
|
|
498 | } |
|
|
499 | |
|
|
500 | sub Coro::guard::DESTROY { |
|
|
501 | ${$_[0]}->(); |
|
|
502 | } |
|
|
503 | |
|
|
504 | |
|
|
505 | =item unblock_sub { ... } |
|
|
506 | |
|
|
507 | This utility function takes a BLOCK or code reference and "unblocks" it, |
|
|
508 | returning the new coderef. This means that the new coderef will return |
|
|
509 | immediately without blocking, returning nothing, while the original code |
|
|
510 | ref will be called (with parameters) from within its own coroutine. |
|
|
511 | |
|
|
512 | The reason this fucntion exists is that many event libraries (such as the |
|
|
513 | venerable L<Event|Event> module) are not coroutine-safe (a weaker form |
|
|
514 | of thread-safety). This means you must not block within event callbacks, |
|
|
515 | otherwise you might suffer from crashes or worse. |
|
|
516 | |
|
|
517 | This function allows your callbacks to block by executing them in another |
|
|
518 | coroutine where it is safe to block. One example where blocking is handy |
|
|
519 | is when you use the L<Coro::AIO|Coro::AIO> functions to save results to |
|
|
520 | disk. |
|
|
521 | |
|
|
522 | In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when |
|
|
523 | creating event callbacks that want to block. |
|
|
524 | |
|
|
525 | =cut |
|
|
526 | |
|
|
527 | our @unblock_queue; |
|
|
528 | |
|
|
529 | # we create a special coro because we want to cede, |
|
|
530 | # to reduce pressure on the coro pool (because most callbacks |
|
|
531 | # return immediately and can be reused) and because we cannot cede |
|
|
532 | # inside an event callback. |
|
|
533 | our $unblock_scheduler = async { |
|
|
534 | while () { |
|
|
535 | while (my $cb = pop @unblock_queue) { |
|
|
536 | # this is an inlined copy of async_pool |
|
|
537 | my $coro = (pop @pool or new Coro \&pool_handler); |
|
|
538 | |
|
|
539 | $coro->{_invoke} = $cb; |
|
|
540 | $coro->ready; |
|
|
541 | cede; # for short-lived callbacks, this reduces pressure on the coro pool |
|
|
542 | } |
|
|
543 | schedule; # sleep well |
|
|
544 | } |
|
|
545 | }; |
|
|
546 | |
|
|
547 | sub unblock_sub(&) { |
|
|
548 | my $cb = shift; |
|
|
549 | |
|
|
550 | sub { |
|
|
551 | unshift @unblock_queue, [$cb, @_]; |
|
|
552 | $unblock_scheduler->ready; |
|
|
553 | } |
|
|
554 | } |
|
|
555 | |
|
|
556 | =back |
|
|
557 | |
326 | =cut |
558 | =cut |
327 | |
559 | |
328 | 1; |
560 | 1; |
329 | |
561 | |
330 | =head1 BUGS/LIMITATIONS |
562 | =head1 BUGS/LIMITATIONS |
… | |
… | |
337 | to allow per-thread schedulers, but Coro::State does not yet allow |
569 | to allow per-thread schedulers, but Coro::State does not yet allow |
338 | this). |
570 | this). |
339 | |
571 | |
340 | =head1 SEE ALSO |
572 | =head1 SEE ALSO |
341 | |
573 | |
342 | L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>, |
574 | Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>. |
343 | L<Coro::Signal>, L<Coro::State>, L<Coro::Timer>, L<Coro::Event>, |
575 | |
344 | L<Coro::Handle>, L<Coro::RWLock>, L<Coro::Socket>. |
576 | Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>. |
|
|
577 | |
|
|
578 | Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>. |
|
|
579 | |
|
|
580 | Embedding: L<Coro:MakeMaker> |
345 | |
581 | |
346 | =head1 AUTHOR |
582 | =head1 AUTHOR |
347 | |
583 | |
348 | Marc Lehmann <pcg@goof.com> |
584 | Marc Lehmann <schmorp@schmorp.de> |
349 | http://home.schmorp.de/ |
585 | http://home.schmorp.de/ |
350 | |
586 | |
351 | =cut |
587 | =cut |
352 | |
588 | |