… | |
… | |
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 | yield; |
19 | cede; |
20 | |
20 | |
21 | =head1 DESCRIPTION |
21 | =head1 DESCRIPTION |
22 | |
22 | |
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23 | This module collection manages coroutines. Coroutines are similar |
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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. |
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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 | |
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35 | In this module, coroutines are defined as "callchain + lexical variables + |
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36 | @_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain, |
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37 | its own set of lexicals and its own set of perls most important global |
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38 | variables. |
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39 | |
23 | =cut |
40 | =cut |
24 | |
41 | |
25 | package Coro; |
42 | package Coro; |
26 | |
43 | |
|
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44 | use strict; |
|
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45 | no warnings "uninitialized"; |
|
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46 | |
27 | use Coro::State; |
47 | use Coro::State; |
28 | |
48 | |
29 | use base Exporter; |
49 | use base qw(Coro::State Exporter); |
30 | |
50 | |
31 | $VERSION = 0.04; |
51 | our $idle; # idle handler |
|
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52 | our $main; # main coroutine |
|
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53 | our $current; # current coroutine |
32 | |
54 | |
33 | @EXPORT = qw(async yield schedule); |
55 | our $VERSION = '3.1'; |
34 | @EXPORT_OK = qw($current); |
56 | |
|
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57 | our @EXPORT = qw(async cede schedule terminate current unblock_sub); |
|
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58 | our %EXPORT_TAGS = ( |
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59 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
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60 | ); |
|
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61 | our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready)); |
35 | |
62 | |
36 | { |
63 | { |
37 | use subs 'async'; |
|
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38 | |
|
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39 | my @async; |
64 | my @async; |
|
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65 | my $init; |
40 | |
66 | |
41 | # this way of handling attributes simply is NOT scalable ;() |
67 | # this way of handling attributes simply is NOT scalable ;() |
42 | sub import { |
68 | sub import { |
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69 | no strict 'refs'; |
|
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70 | |
43 | Coro->export_to_level(1, @_); |
71 | Coro->export_to_level (1, @_); |
|
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72 | |
44 | my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE}; |
73 | my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE}; |
45 | *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub { |
74 | *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub { |
46 | my ($package, $ref) = (shift, shift); |
75 | my ($package, $ref) = (shift, shift); |
47 | my @attrs; |
76 | my @attrs; |
48 | for (@_) { |
77 | for (@_) { |
49 | if ($_ eq "Coro") { |
78 | if ($_ eq "Coro") { |
50 | push @async, $ref; |
79 | push @async, $ref; |
|
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80 | unless ($init++) { |
|
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81 | eval q{ |
|
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82 | sub INIT { |
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83 | &async(pop @async) while @async; |
|
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84 | } |
|
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85 | }; |
|
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86 | } |
51 | } else { |
87 | } else { |
52 | push @attrs, @_; |
88 | push @attrs, $_; |
53 | } |
89 | } |
54 | } |
90 | } |
55 | return $old ? $old->($package, $name, @attrs) : @attrs; |
91 | return $old ? $old->($package, $ref, @attrs) : @attrs; |
56 | }; |
92 | }; |
57 | } |
93 | } |
58 | |
94 | |
59 | sub INIT { |
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60 | async pop @async while @async; |
|
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61 | } |
|
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62 | } |
95 | } |
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96 | |
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97 | =over 4 |
63 | |
98 | |
64 | =item $main |
99 | =item $main |
65 | |
100 | |
66 | This coroutine represents the main program. |
101 | This coroutine represents the main program. |
67 | |
102 | |
68 | =cut |
103 | =cut |
69 | |
104 | |
70 | our $main = new Coro; |
105 | $main = new Coro; |
71 | |
106 | |
72 | =item $current |
107 | =item $current (or as function: current) |
73 | |
108 | |
74 | The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course). |
109 | The current coroutine (the last coroutine switched to). The initial value |
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110 | is C<$main> (of course). |
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111 | |
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112 | This variable is B<strictly> I<read-only>. It is provided for performance |
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113 | reasons. If performance is not essentiel you are encouraged to use the |
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114 | C<Coro::current> function instead. |
75 | |
115 | |
76 | =cut |
116 | =cut |
77 | |
117 | |
78 | # maybe some other module used Coro::Specific before... |
118 | # maybe some other module used Coro::Specific before... |
79 | if ($current) { |
|
|
80 | $main->{specific} = $current->{specific}; |
119 | $main->{specific} = $current->{specific} |
81 | } |
120 | if $current; |
82 | |
121 | |
83 | our $current = $main; |
122 | _set_current $main; |
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123 | |
|
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124 | sub current() { $current } |
84 | |
125 | |
85 | =item $idle |
126 | =item $idle |
86 | |
127 | |
87 | 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 |
88 | 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. |
89 | |
131 | |
90 | =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. |
91 | |
135 | |
92 | # should be done using priorities :( |
136 | Please note that if your callback recursively invokes perl (e.g. for event |
93 | our $idle = new Coro sub { |
137 | handlers), then it must be prepared to be called recursively. |
94 | print STDERR "FATAL: deadlock detected\n"; |
138 | |
95 | 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"); |
96 | }; |
144 | }; |
97 | |
145 | |
98 | # we really need priorities... |
146 | # this coroutine is necessary because a coroutine |
99 | my @ready = (); # the ready queue. hehe, rather broken ;) |
147 | # cannot destroy itself. |
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148 | my @destroy; |
|
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149 | my $manager; $manager = new Coro sub { |
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150 | while () { |
|
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151 | # by overwriting the state object with the manager we destroy it |
|
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152 | # while still being able to schedule this coroutine (in case it has |
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153 | # been readied multiple times. this is harmless since the manager |
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154 | # can be called as many times as neccessary and will always |
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155 | # remove itself from the runqueue |
|
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156 | while (@destroy) { |
|
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157 | my $coro = pop @destroy; |
|
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158 | $coro->{status} ||= []; |
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159 | $_->ready for @{delete $coro->{join} || []}; |
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160 | |
|
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161 | # the next line destroys the coro state, but keeps the |
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162 | # coroutine itself intact (we basically make it a zombie |
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163 | # coroutine that always runs the manager thread, so it's possible |
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164 | # to transfer() to this coroutine). |
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165 | $coro->_clone_state_from ($manager); |
|
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166 | } |
|
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167 | &schedule; |
|
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168 | } |
|
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169 | }; |
100 | |
170 | |
101 | # static methods. not really. |
171 | # static methods. not really. |
102 | |
172 | |
|
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173 | =back |
|
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174 | |
103 | =head2 STATIC METHODS |
175 | =head2 STATIC METHODS |
104 | |
176 | |
105 | Static methods are actually functions that operate on the current process only. |
177 | Static methods are actually functions that operate on the current coroutine only. |
106 | |
178 | |
107 | =over 4 |
179 | =over 4 |
108 | |
180 | |
109 | =item async { ... }; |
181 | =item async { ... } [@args...] |
110 | |
182 | |
111 | Create a new asynchronous process and return it's process object |
183 | Create a new asynchronous coroutine and return it's coroutine object |
112 | (usually unused). When the sub returns the new process is automatically |
184 | (usually unused). When the sub returns the new coroutine is automatically |
113 | terminated. |
185 | terminated. |
114 | |
186 | |
115 | =cut |
187 | Calling C<exit> in a coroutine will not work correctly, so do not do that. |
116 | |
188 | |
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189 | When the coroutine dies, the program will exit, just as in the main |
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190 | program. |
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191 | |
|
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192 | # create a new coroutine that just prints its arguments |
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193 | async { |
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194 | print "@_\n"; |
|
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195 | } 1,2,3,4; |
|
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196 | |
|
|
197 | =cut |
|
|
198 | |
117 | sub async(&) { |
199 | sub async(&@) { |
118 | (new Coro $_[0])->ready; |
200 | my $pid = new Coro @_; |
|
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201 | $pid->ready; |
|
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202 | $pid |
119 | } |
203 | } |
120 | |
204 | |
121 | =item schedule |
205 | =item schedule |
122 | |
206 | |
123 | Calls the scheduler. Please note that the current process will not be put |
207 | Calls the scheduler. Please note that the current coroutine will not be put |
124 | into the ready queue, so calling this function usually means you will |
208 | into the ready queue, so calling this function usually means you will |
125 | never be called again. |
209 | never be called again unless something else (e.g. an event handler) calls |
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210 | ready. |
126 | |
211 | |
127 | =cut |
212 | The canonical way to wait on external events is this: |
128 | |
213 | |
129 | my $prev; |
214 | { |
|
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215 | # remember current coroutine |
|
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216 | my $current = $Coro::current; |
130 | |
217 | |
131 | sub schedule { |
218 | # register a hypothetical event handler |
132 | # should be done using priorities :( |
219 | on_event_invoke sub { |
133 | ($prev, $current) = ($current, shift @ready || $idle); |
220 | # wake up sleeping coroutine |
134 | Coro::State::transfer($prev, $current); |
|
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135 | } |
|
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136 | |
|
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137 | =item yield |
|
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138 | |
|
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139 | Yield to other processes. This function puts the current process into the |
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140 | ready queue and calls C<schedule>. |
|
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141 | |
|
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142 | =cut |
|
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143 | |
|
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144 | sub yield { |
|
|
145 | $current->ready; |
221 | $current->ready; |
146 | &schedule; |
222 | undef $current; |
147 | } |
223 | }; |
148 | |
224 | |
|
|
225 | # call schedule until event occured. |
|
|
226 | # in case we are woken up for other reasons |
|
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227 | # (current still defined), loop. |
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228 | Coro::schedule while $current; |
|
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229 | } |
|
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230 | |
|
|
231 | =item cede |
|
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232 | |
|
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233 | "Cede" to other coroutines. This function puts the current coroutine into the |
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234 | ready queue and calls C<schedule>, which has the effect of giving up the |
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235 | current "timeslice" to other coroutines of the same or higher priority. |
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236 | |
149 | =item terminate |
237 | =item terminate [arg...] |
150 | |
238 | |
151 | Terminates the current process. |
239 | Terminates the current coroutine with the given status values (see L<cancel>). |
152 | |
240 | |
153 | =cut |
241 | =cut |
154 | |
242 | |
155 | sub terminate { |
243 | sub terminate { |
156 | &schedule; |
244 | $current->cancel (@_); |
157 | } |
245 | } |
158 | |
246 | |
159 | =back |
247 | =back |
160 | |
248 | |
161 | # dynamic methods |
249 | # dynamic methods |
162 | |
250 | |
163 | =head2 PROCESS METHODS |
251 | =head2 COROUTINE METHODS |
164 | |
252 | |
165 | These are the methods you can call on process objects. |
253 | These are the methods you can call on coroutine objects. |
166 | |
254 | |
167 | =over 4 |
255 | =over 4 |
168 | |
256 | |
169 | =item new Coro \⊂ |
257 | =item new Coro \&sub [, @args...] |
170 | |
258 | |
171 | Create a new process and return it. When the sub returns the process |
259 | Create a new coroutine and return it. When the sub returns the coroutine |
172 | automatically terminates. To start the process you must first put it into |
260 | automatically terminates as if C<terminate> with the returned values were |
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261 | called. To make the coroutine run you must first put it into the ready queue |
173 | the ready queue by calling the ready method. |
262 | by calling the ready method. |
174 | |
263 | |
|
|
264 | Calling C<exit> in a coroutine will not work correctly, so do not do that. |
|
|
265 | |
175 | =cut |
266 | =cut |
|
|
267 | |
|
|
268 | sub _run_coro { |
|
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269 | terminate &{+shift}; |
|
|
270 | } |
176 | |
271 | |
177 | sub new { |
272 | sub new { |
178 | my $class = shift; |
273 | my $class = shift; |
|
|
274 | |
|
|
275 | $class->SUPER::new (\&_run_coro, @_) |
|
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276 | } |
|
|
277 | |
|
|
278 | =item $success = $coroutine->ready |
|
|
279 | |
|
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280 | Put the given coroutine into the ready queue (according to it's priority) |
|
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281 | and return true. If the coroutine is already in the ready queue, do nothing |
|
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282 | and return false. |
|
|
283 | |
|
|
284 | =item $is_ready = $coroutine->is_ready |
|
|
285 | |
|
|
286 | Return wether the coroutine is currently the ready queue or not, |
|
|
287 | |
|
|
288 | =item $coroutine->cancel (arg...) |
|
|
289 | |
|
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290 | Terminates the given coroutine and makes it return the given arguments as |
|
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291 | status (default: the empty list). |
|
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292 | |
|
|
293 | =cut |
|
|
294 | |
|
|
295 | sub cancel { |
|
|
296 | my $self = shift; |
|
|
297 | $self->{status} = [@_]; |
|
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298 | push @destroy, $self; |
|
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299 | $manager->ready; |
|
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300 | &schedule if $current == $self; |
|
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301 | } |
|
|
302 | |
|
|
303 | =item $coroutine->join |
|
|
304 | |
|
|
305 | Wait until the coroutine terminates and return any values given to the |
|
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306 | C<terminate> or C<cancel> functions. C<join> can be called multiple times |
|
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307 | from multiple coroutine. |
|
|
308 | |
|
|
309 | =cut |
|
|
310 | |
|
|
311 | sub join { |
|
|
312 | my $self = shift; |
|
|
313 | unless ($self->{status}) { |
|
|
314 | push @{$self->{join}}, $current; |
|
|
315 | &schedule; |
|
|
316 | } |
|
|
317 | wantarray ? @{$self->{status}} : $self->{status}[0]; |
|
|
318 | } |
|
|
319 | |
|
|
320 | =item $oldprio = $coroutine->prio ($newprio) |
|
|
321 | |
|
|
322 | Sets (or gets, if the argument is missing) the priority of the |
|
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323 | coroutine. Higher priority coroutines get run before lower priority |
|
|
324 | coroutines. Priorities are small signed integers (currently -4 .. +3), |
|
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325 | that you can refer to using PRIO_xxx constants (use the import tag :prio |
|
|
326 | to get then): |
|
|
327 | |
|
|
328 | PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN |
|
|
329 | 3 > 1 > 0 > -1 > -3 > -4 |
|
|
330 | |
|
|
331 | # set priority to HIGH |
|
|
332 | current->prio(PRIO_HIGH); |
|
|
333 | |
|
|
334 | The idle coroutine ($Coro::idle) always has a lower priority than any |
|
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335 | existing coroutine. |
|
|
336 | |
|
|
337 | Changing the priority of the current coroutine will take effect immediately, |
|
|
338 | but changing the priority of coroutines in the ready queue (but not |
|
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339 | running) will only take effect after the next schedule (of that |
|
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340 | coroutine). This is a bug that will be fixed in some future version. |
|
|
341 | |
|
|
342 | =item $newprio = $coroutine->nice ($change) |
|
|
343 | |
|
|
344 | Similar to C<prio>, but subtract the given value from the priority (i.e. |
|
|
345 | higher values mean lower priority, just as in unix). |
|
|
346 | |
|
|
347 | =item $olddesc = $coroutine->desc ($newdesc) |
|
|
348 | |
|
|
349 | Sets (or gets in case the argument is missing) the description for this |
|
|
350 | coroutine. This is just a free-form string you can associate with a coroutine. |
|
|
351 | |
|
|
352 | =cut |
|
|
353 | |
|
|
354 | sub desc { |
179 | my $proc = $_[0]; |
355 | my $old = $_[0]{desc}; |
180 | bless { |
356 | $_[0]{desc} = $_[1] if @_ > 1; |
181 | _coro_state => new Coro::State ($proc ? sub { &$proc; &terminate } : $proc), |
357 | $old; |
182 | }, $class; |
|
|
183 | } |
|
|
184 | |
|
|
185 | =item $process->ready |
|
|
186 | |
|
|
187 | Put the current process into the ready queue. |
|
|
188 | |
|
|
189 | =cut |
|
|
190 | |
|
|
191 | sub ready { |
|
|
192 | push @ready, $_[0]; |
|
|
193 | } |
358 | } |
194 | |
359 | |
195 | =back |
360 | =back |
196 | |
361 | |
|
|
362 | =head2 GLOBAL FUNCTIONS |
|
|
363 | |
|
|
364 | =over 4 |
|
|
365 | |
|
|
366 | =item Coro::nready |
|
|
367 | |
|
|
368 | Returns the number of coroutines that are currently in the ready state, |
|
|
369 | i.e. that can be swicthed to. The value C<0> means that the only runnable |
|
|
370 | coroutine is the currently running one, so C<cede> would have no effect, |
|
|
371 | and C<schedule> would cause a deadlock unless there is an idle handler |
|
|
372 | that wakes up some coroutines. |
|
|
373 | |
|
|
374 | =item unblock_sub { ... } |
|
|
375 | |
|
|
376 | This utility function takes a BLOCK or code reference and "unblocks" it, |
|
|
377 | returning the new coderef. This means that the new coderef will return |
|
|
378 | immediately without blocking, returning nothing, while the original code |
|
|
379 | ref will be called (with parameters) from within its own coroutine. |
|
|
380 | |
|
|
381 | The reason this fucntion exists is that many event libraries (such as the |
|
|
382 | venerable L<Event|Event> module) are not coroutine-safe (a weaker form |
|
|
383 | of thread-safety). This means you must not block within event callbacks, |
|
|
384 | otherwise you might suffer from crashes or worse. |
|
|
385 | |
|
|
386 | This function allows your callbacks to block by executing them in another |
|
|
387 | coroutine where it is safe to block. One example where blocking is handy |
|
|
388 | is when you use the L<Coro::AIO|Coro::AIO> functions to save results to |
|
|
389 | disk. |
|
|
390 | |
|
|
391 | In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when |
|
|
392 | creating event callbacks that want to block. |
|
|
393 | |
|
|
394 | =cut |
|
|
395 | |
|
|
396 | our @unblock_pool; |
|
|
397 | our @unblock_queue; |
|
|
398 | our $UNBLOCK_POOL_SIZE = 2; |
|
|
399 | |
|
|
400 | sub unblock_handler_ { |
|
|
401 | while () { |
|
|
402 | my ($cb, @arg) = @{ delete $Coro::current->{arg} }; |
|
|
403 | $cb->(@arg); |
|
|
404 | |
|
|
405 | last if @unblock_pool >= $UNBLOCK_POOL_SIZE; |
|
|
406 | push @unblock_pool, $Coro::current; |
|
|
407 | schedule; |
|
|
408 | } |
|
|
409 | } |
|
|
410 | |
|
|
411 | our $unblock_scheduler = async { |
|
|
412 | while () { |
|
|
413 | while (my $cb = pop @unblock_queue) { |
|
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414 | my $handler = (pop @unblock_pool or new Coro \&unblock_handler_); |
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415 | $handler->{arg} = $cb; |
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416 | $handler->ready; |
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417 | cede; |
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418 | } |
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419 | |
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420 | schedule; |
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421 | } |
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422 | }; |
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423 | |
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424 | sub unblock_sub(&) { |
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425 | my $cb = shift; |
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426 | |
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427 | sub { |
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428 | push @unblock_queue, [$cb, @_]; |
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429 | $unblock_scheduler->ready; |
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430 | } |
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431 | } |
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432 | |
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433 | =back |
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434 | |
197 | =cut |
435 | =cut |
198 | |
436 | |
199 | 1; |
437 | 1; |
200 | |
438 | |
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439 | =head1 BUGS/LIMITATIONS |
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440 | |
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441 | - you must make very sure that no coro is still active on global |
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442 | destruction. very bad things might happen otherwise (usually segfaults). |
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443 | |
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444 | - this module is not thread-safe. You should only ever use this module |
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445 | from the same thread (this requirement might be losened in the future |
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446 | to allow per-thread schedulers, but Coro::State does not yet allow |
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447 | this). |
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448 | |
201 | =head1 SEE ALSO |
449 | =head1 SEE ALSO |
202 | |
450 | |
203 | L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>, |
451 | Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>. |
204 | L<Coro::Signal>, L<Coro::State>. |
452 | |
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453 | Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>. |
|
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454 | |
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455 | Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>. |
|
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456 | |
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457 | Embedding: L<Coro:MakeMaker> |
205 | |
458 | |
206 | =head1 AUTHOR |
459 | =head1 AUTHOR |
207 | |
460 | |
208 | Marc Lehmann <pcg@goof.com> |
461 | Marc Lehmann <schmorp@schmorp.de> |
209 | http://www.goof.com/pcg/marc/ |
462 | http://home.schmorp.de/ |
210 | |
463 | |
211 | =cut |
464 | =cut |
212 | |
465 | |