… | |
… | |
6 | |
6 | |
7 | use Coro; |
7 | use Coro; |
8 | |
8 | |
9 | async { |
9 | async { |
10 | # some asynchronous thread of execution |
10 | # some asynchronous thread of execution |
|
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11 | print "2\n"; |
|
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12 | cede; # yield back to main |
|
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13 | print "4\n"; |
11 | }; |
14 | }; |
|
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15 | print "1\n"; |
|
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16 | cede; # yield to coroutine |
|
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17 | print "3\n"; |
|
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18 | cede; # and again |
12 | |
19 | |
13 | # alternatively create an async process like this: |
20 | # use locking |
|
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21 | my $lock = new Coro::Semaphore; |
|
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22 | my $locked; |
14 | |
23 | |
15 | sub some_func : Coro { |
24 | $lock->down; |
16 | # some more async code |
25 | $locked = 1; |
17 | } |
26 | $lock->up; |
18 | |
|
|
19 | yield; |
|
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20 | |
27 | |
21 | =head1 DESCRIPTION |
28 | =head1 DESCRIPTION |
22 | |
29 | |
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30 | This module collection manages coroutines. Coroutines are similar |
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31 | to threads but don't run in parallel at the same time even on SMP |
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32 | machines. The specific flavor of coroutine used in this module also |
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33 | guarantees you that it will not switch between coroutines unless |
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34 | necessary, at easily-identified points in your program, so locking and |
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35 | parallel access are rarely an issue, making coroutine programming much |
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36 | safer than threads programming. |
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37 | |
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38 | (Perl, however, does not natively support real threads but instead does a |
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39 | very slow and memory-intensive emulation of processes using threads. This |
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40 | is a performance win on Windows machines, and a loss everywhere else). |
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41 | |
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42 | In this module, coroutines are defined as "callchain + lexical variables + |
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43 | @_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain, |
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44 | its own set of lexicals and its own set of perls most important global |
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45 | variables (see L<Coro::State> for more configuration). |
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46 | |
23 | =cut |
47 | =cut |
24 | |
48 | |
25 | package Coro; |
49 | package Coro; |
26 | |
50 | |
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51 | use strict; |
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52 | no warnings "uninitialized"; |
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53 | |
27 | use Coro::State; |
54 | use Coro::State; |
28 | |
55 | |
29 | use base Exporter; |
56 | use base qw(Coro::State Exporter); |
30 | |
57 | |
31 | $VERSION = 0.04; |
58 | our $idle; # idle handler |
|
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59 | our $main; # main coroutine |
|
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60 | our $current; # current coroutine |
32 | |
61 | |
33 | @EXPORT = qw(async yield schedule); |
62 | our $VERSION = '4.51'; |
34 | @EXPORT_OK = qw($current); |
63 | |
|
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64 | our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); |
|
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65 | our %EXPORT_TAGS = ( |
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66 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
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67 | ); |
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68 | our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready)); |
35 | |
69 | |
36 | { |
70 | { |
37 | use subs 'async'; |
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38 | |
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39 | my @async; |
71 | my @async; |
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72 | my $init; |
40 | |
73 | |
41 | # this way of handling attributes simply is NOT scalable ;() |
74 | # this way of handling attributes simply is NOT scalable ;() |
42 | sub import { |
75 | sub import { |
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76 | no strict 'refs'; |
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77 | |
43 | Coro->export_to_level(1, @_); |
78 | Coro->export_to_level (1, @_); |
|
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79 | |
44 | my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE}; |
80 | my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE}; |
45 | *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub { |
81 | *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub { |
46 | my ($package, $ref) = (shift, shift); |
82 | my ($package, $ref) = (shift, shift); |
47 | my @attrs; |
83 | my @attrs; |
48 | for (@_) { |
84 | for (@_) { |
49 | if ($_ eq "Coro") { |
85 | if ($_ eq "Coro") { |
50 | push @async, $ref; |
86 | push @async, $ref; |
|
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87 | unless ($init++) { |
|
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88 | eval q{ |
|
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89 | sub INIT { |
|
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90 | &async(pop @async) while @async; |
|
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91 | } |
|
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92 | }; |
|
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93 | } |
51 | } else { |
94 | } else { |
52 | push @attrs, @_; |
95 | push @attrs, $_; |
53 | } |
96 | } |
54 | } |
97 | } |
55 | return $old ? $old->($package, $name, @attrs) : @attrs; |
98 | return $old ? $old->($package, $ref, @attrs) : @attrs; |
56 | }; |
99 | }; |
57 | } |
100 | } |
58 | |
101 | |
59 | sub INIT { |
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60 | async pop @async while @async; |
|
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61 | } |
|
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62 | } |
102 | } |
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103 | |
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104 | =over 4 |
63 | |
105 | |
64 | =item $main |
106 | =item $main |
65 | |
107 | |
66 | This coroutine represents the main program. |
108 | This coroutine represents the main program. |
67 | |
109 | |
68 | =cut |
110 | =cut |
69 | |
111 | |
70 | our $main = new Coro; |
112 | $main = new Coro; |
71 | |
113 | |
72 | =item $current |
114 | =item $current (or as function: current) |
73 | |
115 | |
74 | The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course). |
116 | The current coroutine (the last coroutine switched to). The initial value |
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117 | is C<$main> (of course). |
75 | |
118 | |
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119 | This variable is B<strictly> I<read-only>. It is provided for performance |
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120 | reasons. If performance is not essential you are encouraged to use the |
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121 | C<Coro::current> function instead. |
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122 | |
76 | =cut |
123 | =cut |
|
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124 | |
|
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125 | $main->{desc} = "[main::]"; |
77 | |
126 | |
78 | # maybe some other module used Coro::Specific before... |
127 | # maybe some other module used Coro::Specific before... |
79 | if ($current) { |
|
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80 | $main->{specific} = $current->{specific}; |
128 | $main->{_specific} = $current->{_specific} |
81 | } |
129 | if $current; |
82 | |
130 | |
83 | our $current = $main; |
131 | _set_current $main; |
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132 | |
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133 | sub current() { $current } |
84 | |
134 | |
85 | =item $idle |
135 | =item $idle |
86 | |
136 | |
87 | The coroutine to switch to when no other coroutine is running. The default |
137 | A callback that is called whenever the scheduler finds no ready coroutines |
88 | implementation prints "FATAL: deadlock detected" and exits. |
138 | to run. The default implementation prints "FATAL: deadlock detected" and |
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139 | exits, because the program has no other way to continue. |
89 | |
140 | |
90 | =cut |
141 | This hook is overwritten by modules such as C<Coro::Timer> and |
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142 | C<Coro::Event> to wait on an external event that hopefully wake up a |
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143 | coroutine so the scheduler can run it. |
91 | |
144 | |
92 | # should be done using priorities :( |
145 | Please note that if your callback recursively invokes perl (e.g. for event |
93 | our $idle = new Coro sub { |
146 | handlers), then it must be prepared to be called recursively itself. |
94 | print STDERR "FATAL: deadlock detected\n"; |
147 | |
95 | exit(51); |
148 | =cut |
|
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149 | |
|
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150 | $idle = sub { |
|
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151 | require Carp; |
|
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152 | Carp::croak ("FATAL: deadlock detected"); |
96 | }; |
153 | }; |
97 | |
154 | |
98 | # we really need priorities... |
155 | sub _cancel { |
99 | my @ready = (); # the ready queue. hehe, rather broken ;) |
156 | my ($self) = @_; |
|
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157 | |
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158 | # free coroutine data and mark as destructed |
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159 | $self->_destroy |
|
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160 | or return; |
|
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161 | |
|
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162 | # call all destruction callbacks |
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163 | $_->(@{$self->{_status}}) |
|
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164 | for @{(delete $self->{_on_destroy}) || []}; |
|
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165 | } |
|
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166 | |
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167 | # this coroutine is necessary because a coroutine |
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168 | # cannot destroy itself. |
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169 | my @destroy; |
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170 | my $manager; |
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171 | |
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172 | $manager = new Coro sub { |
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173 | while () { |
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174 | (shift @destroy)->_cancel |
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175 | while @destroy; |
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176 | |
|
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177 | &schedule; |
|
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178 | } |
|
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179 | }; |
|
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180 | $manager->desc ("[coro manager]"); |
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181 | $manager->prio (PRIO_MAX); |
100 | |
182 | |
101 | # static methods. not really. |
183 | # static methods. not really. |
102 | |
184 | |
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185 | =back |
|
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186 | |
103 | =head2 STATIC METHODS |
187 | =head2 STATIC METHODS |
104 | |
188 | |
105 | Static methods are actually functions that operate on the current process only. |
189 | Static methods are actually functions that operate on the current coroutine only. |
106 | |
190 | |
107 | =over 4 |
191 | =over 4 |
108 | |
192 | |
109 | =item async { ... }; |
193 | =item async { ... } [@args...] |
110 | |
194 | |
111 | Create a new asynchronous process and return it's process object |
195 | Create a new asynchronous coroutine and return it's coroutine object |
112 | (usually unused). When the sub returns the new process is automatically |
196 | (usually unused). When the sub returns the new coroutine is automatically |
113 | terminated. |
197 | terminated. |
114 | |
198 | |
115 | =cut |
199 | See the C<Coro::State::new> constructor for info about the coroutine |
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200 | environment in which coroutines run. |
116 | |
201 | |
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202 | Calling C<exit> in a coroutine will do the same as calling exit outside |
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203 | the coroutine. Likewise, when the coroutine dies, the program will exit, |
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204 | just as it would in the main program. |
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205 | |
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206 | # create a new coroutine that just prints its arguments |
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207 | async { |
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208 | print "@_\n"; |
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209 | } 1,2,3,4; |
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210 | |
|
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211 | =cut |
|
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212 | |
117 | sub async(&) { |
213 | sub async(&@) { |
118 | my $pid = new Coro $_[0]; |
214 | my $coro = new Coro @_; |
119 | $pid->ready; |
215 | $coro->ready; |
120 | $pid; |
216 | $coro |
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217 | } |
|
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218 | |
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219 | =item async_pool { ... } [@args...] |
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220 | |
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221 | Similar to C<async>, but uses a coroutine pool, so you should not call |
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222 | terminate or join (although you are allowed to), and you get a coroutine |
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223 | that might have executed other code already (which can be good or bad :). |
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224 | |
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225 | Also, the block is executed in an C<eval> context and a warning will be |
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226 | issued in case of an exception instead of terminating the program, as |
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227 | C<async> does. As the coroutine is being reused, stuff like C<on_destroy> |
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228 | will not work in the expected way, unless you call terminate or cancel, |
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229 | which somehow defeats the purpose of pooling. |
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230 | |
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231 | The priority will be reset to C<0> after each job, tracing will be |
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232 | disabled, the description will be reset and the default output filehandle |
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233 | gets restored, so you can change alkl these. Otherwise the coroutine will |
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234 | be re-used "as-is": most notably if you change other per-coroutine global |
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235 | stuff such as C<$/> you need to revert that change, which is most simply |
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236 | done by using local as in C< local $/ >. |
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237 | |
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238 | The pool size is limited to 8 idle coroutines (this can be adjusted by |
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239 | changing $Coro::POOL_SIZE), and there can be as many non-idle coros as |
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240 | required. |
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241 | |
|
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242 | If you are concerned about pooled coroutines growing a lot because a |
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243 | single C<async_pool> used a lot of stackspace you can e.g. C<async_pool |
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244 | { terminate }> once per second or so to slowly replenish the pool. In |
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245 | addition to that, when the stacks used by a handler grows larger than 16kb |
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246 | (adjustable with $Coro::POOL_RSS) it will also exit. |
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247 | |
|
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248 | =cut |
|
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249 | |
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250 | our $POOL_SIZE = 8; |
|
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251 | our $POOL_RSS = 16 * 1024; |
|
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252 | our @async_pool; |
|
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253 | |
|
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254 | sub pool_handler { |
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255 | my $cb; |
|
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256 | |
|
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257 | while () { |
|
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258 | eval { |
|
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259 | while () { |
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260 | _pool_1 $cb; |
|
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261 | &$cb; |
|
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262 | _pool_2 $cb; |
|
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263 | &schedule; |
|
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264 | } |
|
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265 | }; |
|
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266 | |
|
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267 | last if $@ eq "\3async_pool terminate\2\n"; |
|
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268 | warn $@ if $@; |
|
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269 | } |
|
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270 | } |
|
|
271 | |
|
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272 | sub async_pool(&@) { |
|
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273 | # this is also inlined into the unlock_scheduler |
|
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274 | my $coro = (pop @async_pool) || new Coro \&pool_handler; |
|
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275 | |
|
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276 | $coro->{_invoke} = [@_]; |
|
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277 | $coro->ready; |
|
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278 | |
|
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279 | $coro |
121 | } |
280 | } |
122 | |
281 | |
123 | =item schedule |
282 | =item schedule |
124 | |
283 | |
125 | Calls the scheduler. Please note that the current process will not be put |
284 | Calls the scheduler. Please note that the current coroutine will not be put |
126 | into the ready queue, so calling this function usually means you will |
285 | into the ready queue, so calling this function usually means you will |
127 | never be called again. |
286 | never be called again unless something else (e.g. an event handler) calls |
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287 | ready. |
128 | |
288 | |
129 | =cut |
289 | The canonical way to wait on external events is this: |
130 | |
290 | |
131 | my $prev; |
291 | { |
|
|
292 | # remember current coroutine |
|
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293 | my $current = $Coro::current; |
132 | |
294 | |
133 | sub schedule { |
295 | # register a hypothetical event handler |
134 | # should be done using priorities :( |
296 | on_event_invoke sub { |
135 | ($prev, $current) = ($current, shift @ready || $idle); |
297 | # wake up sleeping coroutine |
136 | Coro::State::transfer($prev, $current); |
|
|
137 | } |
|
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138 | |
|
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139 | =item yield |
|
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140 | |
|
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141 | Yield to other processes. This function puts the current process into the |
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142 | ready queue and calls C<schedule>. |
|
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143 | |
|
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144 | =cut |
|
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145 | |
|
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146 | sub yield { |
|
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147 | $current->ready; |
298 | $current->ready; |
148 | &schedule; |
299 | undef $current; |
149 | } |
300 | }; |
150 | |
301 | |
|
|
302 | # call schedule until event occurred. |
|
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303 | # in case we are woken up for other reasons |
|
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304 | # (current still defined), loop. |
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305 | Coro::schedule while $current; |
|
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306 | } |
|
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307 | |
|
|
308 | =item cede |
|
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309 | |
|
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310 | "Cede" to other coroutines. This function puts the current coroutine into the |
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311 | ready queue and calls C<schedule>, which has the effect of giving up the |
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312 | current "timeslice" to other coroutines of the same or higher priority. |
|
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313 | |
|
|
314 | =item Coro::cede_notself |
|
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315 | |
|
|
316 | Works like cede, but is not exported by default and will cede to any |
|
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317 | coroutine, regardless of priority, once. |
|
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318 | |
151 | =item terminate |
319 | =item terminate [arg...] |
152 | |
320 | |
153 | Terminates the current process. |
321 | Terminates the current coroutine with the given status values (see L<cancel>). |
|
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322 | |
|
|
323 | =item killall |
|
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324 | |
|
|
325 | Kills/terminates/cancels all coroutines except the currently running |
|
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326 | one. This is useful after a fork, either in the child or the parent, as |
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327 | usually only one of them should inherit the running coroutines. |
154 | |
328 | |
155 | =cut |
329 | =cut |
156 | |
330 | |
157 | sub terminate { |
331 | sub terminate { |
158 | &schedule; |
332 | $current->cancel (@_); |
|
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333 | } |
|
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334 | |
|
|
335 | sub killall { |
|
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336 | for (Coro::State::list) { |
|
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337 | $_->cancel |
|
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338 | if $_ != $current && UNIVERSAL::isa $_, "Coro"; |
|
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339 | } |
159 | } |
340 | } |
160 | |
341 | |
161 | =back |
342 | =back |
162 | |
343 | |
163 | # dynamic methods |
344 | # dynamic methods |
164 | |
345 | |
165 | =head2 PROCESS METHODS |
346 | =head2 COROUTINE METHODS |
166 | |
347 | |
167 | These are the methods you can call on process objects. |
348 | These are the methods you can call on coroutine objects. |
168 | |
349 | |
169 | =over 4 |
350 | =over 4 |
170 | |
351 | |
171 | =item new Coro \⊂ |
352 | =item new Coro \&sub [, @args...] |
172 | |
353 | |
173 | Create a new process and return it. When the sub returns the process |
354 | Create a new coroutine and return it. When the sub returns the coroutine |
174 | automatically terminates. To start the process you must first put it into |
355 | automatically terminates as if C<terminate> with the returned values were |
|
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356 | called. To make the coroutine run you must first put it into the ready queue |
175 | the ready queue by calling the ready method. |
357 | by calling the ready method. |
176 | |
358 | |
|
|
359 | See C<async> and C<Coro::State::new> for additional info about the |
|
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360 | coroutine environment. |
|
|
361 | |
177 | =cut |
362 | =cut |
|
|
363 | |
|
|
364 | sub _run_coro { |
|
|
365 | terminate &{+shift}; |
|
|
366 | } |
178 | |
367 | |
179 | sub new { |
368 | sub new { |
180 | my $class = shift; |
369 | my $class = shift; |
|
|
370 | |
|
|
371 | $class->SUPER::new (\&_run_coro, @_) |
|
|
372 | } |
|
|
373 | |
|
|
374 | =item $success = $coroutine->ready |
|
|
375 | |
|
|
376 | Put the given coroutine into the ready queue (according to it's priority) |
|
|
377 | and return true. If the coroutine is already in the ready queue, do nothing |
|
|
378 | and return false. |
|
|
379 | |
|
|
380 | =item $is_ready = $coroutine->is_ready |
|
|
381 | |
|
|
382 | Return wether the coroutine is currently the ready queue or not, |
|
|
383 | |
|
|
384 | =item $coroutine->cancel (arg...) |
|
|
385 | |
|
|
386 | Terminates the given coroutine and makes it return the given arguments as |
|
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387 | status (default: the empty list). Never returns if the coroutine is the |
|
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388 | current coroutine. |
|
|
389 | |
|
|
390 | =cut |
|
|
391 | |
|
|
392 | sub cancel { |
|
|
393 | my $self = shift; |
|
|
394 | $self->{_status} = [@_]; |
|
|
395 | |
|
|
396 | if ($current == $self) { |
|
|
397 | push @destroy, $self; |
|
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398 | $manager->ready; |
|
|
399 | &schedule while 1; |
|
|
400 | } else { |
|
|
401 | $self->_cancel; |
|
|
402 | } |
|
|
403 | } |
|
|
404 | |
|
|
405 | =item $coroutine->join |
|
|
406 | |
|
|
407 | Wait until the coroutine terminates and return any values given to the |
|
|
408 | C<terminate> or C<cancel> functions. C<join> can be called concurrently |
|
|
409 | from multiple coroutines. |
|
|
410 | |
|
|
411 | =cut |
|
|
412 | |
|
|
413 | sub join { |
|
|
414 | my $self = shift; |
|
|
415 | |
|
|
416 | unless ($self->{_status}) { |
|
|
417 | my $current = $current; |
|
|
418 | |
|
|
419 | push @{$self->{_on_destroy}}, sub { |
|
|
420 | $current->ready; |
|
|
421 | undef $current; |
|
|
422 | }; |
|
|
423 | |
|
|
424 | &schedule while $current; |
|
|
425 | } |
|
|
426 | |
|
|
427 | wantarray ? @{$self->{_status}} : $self->{_status}[0]; |
|
|
428 | } |
|
|
429 | |
|
|
430 | =item $coroutine->on_destroy (\&cb) |
|
|
431 | |
|
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432 | Registers a callback that is called when this coroutine gets destroyed, |
|
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433 | but before it is joined. The callback gets passed the terminate arguments, |
|
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434 | if any. |
|
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435 | |
|
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436 | =cut |
|
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437 | |
|
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438 | sub on_destroy { |
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439 | my ($self, $cb) = @_; |
|
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440 | |
|
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441 | push @{ $self->{_on_destroy} }, $cb; |
|
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442 | } |
|
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443 | |
|
|
444 | =item $oldprio = $coroutine->prio ($newprio) |
|
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445 | |
|
|
446 | Sets (or gets, if the argument is missing) the priority of the |
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447 | coroutine. Higher priority coroutines get run before lower priority |
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448 | coroutines. Priorities are small signed integers (currently -4 .. +3), |
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449 | that you can refer to using PRIO_xxx constants (use the import tag :prio |
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450 | to get then): |
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451 | |
|
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452 | PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN |
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453 | 3 > 1 > 0 > -1 > -3 > -4 |
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454 | |
|
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455 | # set priority to HIGH |
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456 | current->prio(PRIO_HIGH); |
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457 | |
|
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458 | The idle coroutine ($Coro::idle) always has a lower priority than any |
|
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459 | existing coroutine. |
|
|
460 | |
|
|
461 | Changing the priority of the current coroutine will take effect immediately, |
|
|
462 | but changing the priority of coroutines in the ready queue (but not |
|
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463 | running) will only take effect after the next schedule (of that |
|
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464 | coroutine). This is a bug that will be fixed in some future version. |
|
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465 | |
|
|
466 | =item $newprio = $coroutine->nice ($change) |
|
|
467 | |
|
|
468 | Similar to C<prio>, but subtract the given value from the priority (i.e. |
|
|
469 | higher values mean lower priority, just as in unix). |
|
|
470 | |
|
|
471 | =item $olddesc = $coroutine->desc ($newdesc) |
|
|
472 | |
|
|
473 | Sets (or gets in case the argument is missing) the description for this |
|
|
474 | coroutine. This is just a free-form string you can associate with a coroutine. |
|
|
475 | |
|
|
476 | This method simply sets the C<< $coroutine->{desc} >> member to the given string. You |
|
|
477 | can modify this member directly if you wish. |
|
|
478 | |
|
|
479 | =item $coroutine->throw ([$scalar]) |
|
|
480 | |
|
|
481 | If C<$throw> is specified and defined, it will be thrown as an exception |
|
|
482 | inside the coroutine at the next convinient point in time (usually after |
|
|
483 | it gains control at the next schedule/transfer/cede). Otherwise clears the |
|
|
484 | exception object. |
|
|
485 | |
|
|
486 | The exception object will be thrown "as is" with the specified scalar in |
|
|
487 | C<$@>, i.e. if it is a string, no line number or newline will be appended |
|
|
488 | (unlike with C<die>). |
|
|
489 | |
|
|
490 | This can be used as a softer means than C<cancel> to ask a coroutine to |
|
|
491 | end itself, although there is no guarentee that the exception will lead to |
|
|
492 | termination, and if the exception isn't caught it might well end the whole |
|
|
493 | program. |
|
|
494 | |
|
|
495 | =cut |
|
|
496 | |
|
|
497 | sub desc { |
181 | my $proc = $_[0]; |
498 | my $old = $_[0]{desc}; |
182 | bless { |
499 | $_[0]{desc} = $_[1] if @_ > 1; |
183 | _coro_state => new Coro::State ($proc ? sub { &$proc; &terminate } : $proc), |
500 | $old; |
184 | }, $class; |
|
|
185 | } |
|
|
186 | |
|
|
187 | =item $process->ready |
|
|
188 | |
|
|
189 | Put the current process into the ready queue. |
|
|
190 | |
|
|
191 | =cut |
|
|
192 | |
|
|
193 | sub ready { |
|
|
194 | push @ready, $_[0]; |
|
|
195 | } |
501 | } |
196 | |
502 | |
197 | =back |
503 | =back |
198 | |
504 | |
|
|
505 | =head2 GLOBAL FUNCTIONS |
|
|
506 | |
|
|
507 | =over 4 |
|
|
508 | |
|
|
509 | =item Coro::nready |
|
|
510 | |
|
|
511 | Returns the number of coroutines that are currently in the ready state, |
|
|
512 | i.e. that can be switched to. The value C<0> means that the only runnable |
|
|
513 | coroutine is the currently running one, so C<cede> would have no effect, |
|
|
514 | and C<schedule> would cause a deadlock unless there is an idle handler |
|
|
515 | that wakes up some coroutines. |
|
|
516 | |
|
|
517 | =item my $guard = Coro::guard { ... } |
|
|
518 | |
|
|
519 | This creates and returns a guard object. Nothing happens until the object |
|
|
520 | gets destroyed, in which case the codeblock given as argument will be |
|
|
521 | executed. This is useful to free locks or other resources in case of a |
|
|
522 | runtime error or when the coroutine gets canceled, as in both cases the |
|
|
523 | guard block will be executed. The guard object supports only one method, |
|
|
524 | C<< ->cancel >>, which will keep the codeblock from being executed. |
|
|
525 | |
|
|
526 | Example: set some flag and clear it again when the coroutine gets canceled |
|
|
527 | or the function returns: |
|
|
528 | |
|
|
529 | sub do_something { |
|
|
530 | my $guard = Coro::guard { $busy = 0 }; |
|
|
531 | $busy = 1; |
|
|
532 | |
|
|
533 | # do something that requires $busy to be true |
|
|
534 | } |
|
|
535 | |
|
|
536 | =cut |
|
|
537 | |
|
|
538 | sub guard(&) { |
|
|
539 | bless \(my $cb = $_[0]), "Coro::guard" |
|
|
540 | } |
|
|
541 | |
|
|
542 | sub Coro::guard::cancel { |
|
|
543 | ${$_[0]} = sub { }; |
|
|
544 | } |
|
|
545 | |
|
|
546 | sub Coro::guard::DESTROY { |
|
|
547 | ${$_[0]}->(); |
|
|
548 | } |
|
|
549 | |
|
|
550 | |
|
|
551 | =item unblock_sub { ... } |
|
|
552 | |
|
|
553 | This utility function takes a BLOCK or code reference and "unblocks" it, |
|
|
554 | returning the new coderef. This means that the new coderef will return |
|
|
555 | immediately without blocking, returning nothing, while the original code |
|
|
556 | ref will be called (with parameters) from within its own coroutine. |
|
|
557 | |
|
|
558 | The reason this function exists is that many event libraries (such as the |
|
|
559 | venerable L<Event|Event> module) are not coroutine-safe (a weaker form |
|
|
560 | of thread-safety). This means you must not block within event callbacks, |
|
|
561 | otherwise you might suffer from crashes or worse. |
|
|
562 | |
|
|
563 | This function allows your callbacks to block by executing them in another |
|
|
564 | coroutine where it is safe to block. One example where blocking is handy |
|
|
565 | is when you use the L<Coro::AIO|Coro::AIO> functions to save results to |
|
|
566 | disk. |
|
|
567 | |
|
|
568 | In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when |
|
|
569 | creating event callbacks that want to block. |
|
|
570 | |
|
|
571 | =cut |
|
|
572 | |
|
|
573 | our @unblock_queue; |
|
|
574 | |
|
|
575 | # we create a special coro because we want to cede, |
|
|
576 | # to reduce pressure on the coro pool (because most callbacks |
|
|
577 | # return immediately and can be reused) and because we cannot cede |
|
|
578 | # inside an event callback. |
|
|
579 | our $unblock_scheduler = new Coro sub { |
|
|
580 | while () { |
|
|
581 | while (my $cb = pop @unblock_queue) { |
|
|
582 | # this is an inlined copy of async_pool |
|
|
583 | my $coro = (pop @async_pool) || new Coro \&pool_handler; |
|
|
584 | |
|
|
585 | $coro->{_invoke} = $cb; |
|
|
586 | $coro->ready; |
|
|
587 | cede; # for short-lived callbacks, this reduces pressure on the coro pool |
|
|
588 | } |
|
|
589 | schedule; # sleep well |
|
|
590 | } |
|
|
591 | }; |
|
|
592 | $unblock_scheduler->desc ("[unblock_sub scheduler]"); |
|
|
593 | |
|
|
594 | sub unblock_sub(&) { |
|
|
595 | my $cb = shift; |
|
|
596 | |
|
|
597 | sub { |
|
|
598 | unshift @unblock_queue, [$cb, @_]; |
|
|
599 | $unblock_scheduler->ready; |
|
|
600 | } |
|
|
601 | } |
|
|
602 | |
|
|
603 | =back |
|
|
604 | |
199 | =cut |
605 | =cut |
200 | |
606 | |
201 | 1; |
607 | 1; |
202 | |
608 | |
|
|
609 | =head1 BUGS/LIMITATIONS |
|
|
610 | |
|
|
611 | - you must make very sure that no coro is still active on global |
|
|
612 | destruction. very bad things might happen otherwise (usually segfaults). |
|
|
613 | |
|
|
614 | - this module is not thread-safe. You should only ever use this module |
|
|
615 | from the same thread (this requirement might be loosened in the future |
|
|
616 | to allow per-thread schedulers, but Coro::State does not yet allow |
|
|
617 | this). |
|
|
618 | |
203 | =head1 SEE ALSO |
619 | =head1 SEE ALSO |
204 | |
620 | |
205 | L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>, |
621 | Lower level Configuration, Coroutine Environment: L<Coro::State>. |
206 | L<Coro::Signal>, L<Coro::State>, L<Coro::Event>. |
622 | |
|
|
623 | Debugging: L<Coro::Debug>. |
|
|
624 | |
|
|
625 | Support/Utility: L<Coro::Specific>, L<Coro::Util>. |
|
|
626 | |
|
|
627 | Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>. |
|
|
628 | |
|
|
629 | Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>. |
|
|
630 | |
|
|
631 | Compatibility: L<Coro::LWP>, L<Coro::Storable>, L<Coro::Select>. |
|
|
632 | |
|
|
633 | Embedding: L<Coro::MakeMaker>. |
207 | |
634 | |
208 | =head1 AUTHOR |
635 | =head1 AUTHOR |
209 | |
636 | |
210 | Marc Lehmann <pcg@goof.com> |
637 | Marc Lehmann <schmorp@schmorp.de> |
211 | http://www.goof.com/pcg/marc/ |
638 | http://home.schmorp.de/ |
212 | |
639 | |
213 | =cut |
640 | =cut |
214 | |
641 | |