1 | =head1 NAME |
1 | =head1 NAME |
2 | |
2 | |
3 | Coro - create and manage coroutines |
3 | Coro - coroutine process abstraction |
4 | |
4 | |
5 | =head1 SYNOPSIS |
5 | =head1 SYNOPSIS |
6 | |
6 | |
7 | use Coro; |
7 | use Coro; |
8 | |
8 | |
9 | $new = new Coro sub { |
9 | async { |
10 | print "in coroutine, switching back\n"; |
10 | # some asynchronous thread of execution |
11 | $Coro::main->resume; |
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12 | print "in coroutine again, switching back\n"; |
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13 | $Coro::main->resume; |
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14 | }; |
11 | }; |
15 | |
12 | |
16 | print "in main, switching to coroutine\n"; |
13 | # alternatively create an async process like this: |
17 | $new->resume; |
14 | |
18 | print "back in main, switch to coroutine again\n"; |
15 | sub some_func : Coro { |
19 | $new->resume; |
16 | # some more async code |
20 | print "back in main\n"; |
17 | } |
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18 | |
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19 | cede; |
21 | |
20 | |
22 | =head1 DESCRIPTION |
21 | =head1 DESCRIPTION |
23 | |
22 | |
24 | This module implements coroutines. Coroutines, similar to continuations, |
23 | This module collection manages coroutines. Coroutines are similar to |
25 | allow you to run more than one "thread of execution" in parallel. Unlike |
24 | threads but don't run in parallel. |
26 | threads this, only voluntary switching is used so locking problems are |
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27 | greatly reduced. |
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28 | |
25 | |
29 | Although this is the "main" module of the Coro family it provides only |
26 | In this module, coroutines are defined as "callchain + lexical variables |
30 | low-level functionality. See L<Coro::Process> and related modules for a |
27 | + @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own |
31 | more useful process abstraction including scheduling. |
28 | callchain, it's own set of lexicals and it's own set of perl's most |
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29 | important global variables. |
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30 | |
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31 | =cut |
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32 | |
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33 | package Coro; |
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34 | |
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35 | no warnings qw(uninitialized); |
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36 | |
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37 | use Coro::State; |
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38 | |
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39 | use base Exporter; |
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40 | |
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41 | $VERSION = 0.53; |
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42 | |
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43 | @EXPORT = qw(async cede schedule terminate current); |
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44 | %EXPORT_TAGS = ( |
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45 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
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46 | ); |
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47 | @EXPORT_OK = @{$EXPORT_TAGS{prio}}; |
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48 | |
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49 | { |
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50 | my @async; |
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51 | my $init; |
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52 | |
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53 | # this way of handling attributes simply is NOT scalable ;() |
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54 | sub import { |
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55 | Coro->export_to_level(1, @_); |
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56 | my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE}; |
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57 | *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub { |
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58 | my ($package, $ref) = (shift, shift); |
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59 | my @attrs; |
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60 | for (@_) { |
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61 | if ($_ eq "Coro") { |
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62 | push @async, $ref; |
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63 | unless ($init++) { |
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64 | eval q{ |
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65 | sub INIT { |
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66 | &async(pop @async) while @async; |
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67 | } |
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68 | }; |
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69 | } |
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70 | } else { |
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71 | push @attrs, $_; |
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72 | } |
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73 | } |
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74 | return $old ? $old->($package, $ref, @attrs) : @attrs; |
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75 | }; |
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76 | } |
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77 | |
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78 | } |
32 | |
79 | |
33 | =over 4 |
80 | =over 4 |
34 | |
81 | |
35 | =cut |
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36 | |
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37 | package Coro; |
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38 | |
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39 | BEGIN { |
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40 | $VERSION = 0.03; |
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41 | |
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42 | require XSLoader; |
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43 | XSLoader::load Coro, $VERSION; |
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44 | } |
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45 | |
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46 | =item $main |
82 | =item $main |
47 | |
83 | |
48 | This coroutine represents the main program. |
84 | This coroutine represents the main program. |
49 | |
85 | |
50 | =item $current |
86 | =cut |
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87 | |
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88 | our $main = new Coro; |
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89 | |
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90 | =item $current (or as function: current) |
51 | |
91 | |
52 | The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course). |
92 | The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course). |
53 | |
93 | |
54 | =cut |
94 | =cut |
55 | |
95 | |
56 | $main = $current = _newprocess { |
96 | # maybe some other module used Coro::Specific before... |
57 | # never being called |
97 | if ($current) { |
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98 | $main->{specific} = $current->{specific}; |
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99 | } |
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100 | |
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101 | our $current = $main; |
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102 | |
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103 | sub current() { $current } |
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104 | |
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105 | =item $idle |
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106 | |
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107 | The coroutine to switch to when no other coroutine is running. The default |
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108 | implementation prints "FATAL: deadlock detected" and exits. |
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109 | |
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110 | =cut |
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111 | |
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112 | # should be done using priorities :( |
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113 | our $idle = new Coro sub { |
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114 | print STDERR "FATAL: deadlock detected\n"; |
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115 | exit(51); |
58 | }; |
116 | }; |
59 | |
117 | |
60 | =item $error, $error_msg, $error_coro |
118 | # this coroutine is necessary because a coroutine |
61 | |
119 | # cannot destroy itself. |
62 | This coroutine will be called on fatal errors. C<$error_msg> and |
120 | my @destroy; |
63 | C<$error_coro> return the error message and the error-causing coroutine, |
121 | my $manager; |
64 | respectively. |
122 | $manager = new Coro sub { |
65 | |
123 | while() { |
66 | =cut |
124 | # by overwriting the state object with the manager we destroy it |
67 | |
125 | # while still being able to schedule this coroutine (in case it has |
68 | $error_msg = |
126 | # been readied multiple times. this is harmless since the manager |
69 | $error_coro = undef; |
127 | # can be called as many times as neccessary and will always |
70 | |
128 | # remove itself from the runqueue |
71 | $error = _newprocess { |
129 | while (@destroy) { |
72 | print STDERR "FATAL: $error_msg\nprogram aborted\n"; |
130 | my $coro = pop @destroy; |
73 | exit 250; |
131 | $coro->{status} ||= []; |
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132 | $_->ready for @{delete $coro->{join} || []}; |
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133 | $coro->{_coro_state} = $manager->{_coro_state}; |
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134 | } |
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135 | &schedule; |
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136 | } |
74 | }; |
137 | }; |
75 | |
138 | |
76 | =item $coro = new $coderef [, @args] |
139 | # static methods. not really. |
77 | |
140 | |
78 | Create a new coroutine and return it. The first C<resume> call to this |
141 | =back |
79 | coroutine will start execution at the given coderef. If it returns it |
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80 | should return a coroutine to switch to. If, after returning, the coroutine |
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81 | is C<resume>d again it starts execution again at the givne coderef. |
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82 | |
142 | |
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143 | =head2 STATIC METHODS |
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144 | |
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145 | Static methods are actually functions that operate on the current process only. |
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146 | |
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147 | =over 4 |
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148 | |
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149 | =item async { ... } [@args...] |
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150 | |
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151 | Create a new asynchronous process and return it's process object |
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152 | (usually unused). When the sub returns the new process is automatically |
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153 | terminated. |
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154 | |
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155 | # create a new coroutine that just prints its arguments |
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156 | async { |
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157 | print "@_\n"; |
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158 | } 1,2,3,4; |
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159 | |
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160 | The coderef you submit MUST NOT be a closure that refers to variables |
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161 | in an outer scope. This does NOT work. Pass arguments into it instead. |
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162 | |
83 | =cut |
163 | =cut |
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164 | |
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165 | sub async(&@) { |
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166 | my $pid = new Coro @_; |
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167 | $manager->ready; # this ensures that the stack is cloned from the manager |
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168 | $pid->ready; |
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169 | $pid; |
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170 | } |
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171 | |
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172 | =item schedule |
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173 | |
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174 | Calls the scheduler. Please note that the current process will not be put |
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175 | into the ready queue, so calling this function usually means you will |
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176 | never be called again. |
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177 | |
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178 | =cut |
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179 | |
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180 | =item cede |
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181 | |
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182 | "Cede" to other processes. This function puts the current process into the |
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183 | ready queue and calls C<schedule>, which has the effect of giving up the |
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184 | current "timeslice" to other coroutines of the same or higher priority. |
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185 | |
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186 | =cut |
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187 | |
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188 | =item terminate [arg...] |
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189 | |
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190 | Terminates the current process. |
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191 | |
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192 | Future versions of this function will allow result arguments. |
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193 | |
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194 | =cut |
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195 | |
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196 | sub terminate { |
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197 | $current->{status} = [@_]; |
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198 | $current->cancel; |
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199 | &schedule; |
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200 | die; # NORETURN |
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201 | } |
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202 | |
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203 | =back |
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204 | |
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205 | # dynamic methods |
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206 | |
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207 | =head2 PROCESS METHODS |
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208 | |
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209 | These are the methods you can call on process objects. |
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210 | |
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211 | =over 4 |
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212 | |
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213 | =item new Coro \&sub [, @args...] |
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214 | |
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215 | Create a new process and return it. When the sub returns the process |
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216 | automatically terminates as if C<terminate> with the returned values were |
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217 | called. To make the process run you must first put it into the ready queue |
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218 | by calling the ready method. |
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219 | |
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220 | =cut |
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221 | |
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222 | sub _newcoro { |
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223 | terminate &{+shift}; |
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224 | } |
84 | |
225 | |
85 | sub new { |
226 | sub new { |
86 | my $class = $_[0]; |
227 | my $class = shift; |
87 | my $proc = $_[1]; |
228 | bless { |
88 | bless _newprocess { |
229 | _coro_state => (new Coro::State $_[0] && \&_newcoro, @_), |
89 | do { |
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90 | eval { &$proc->resume }; |
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91 | if ($@) { |
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92 | ($error_msg, $error_coro) = ($@, $current); |
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93 | $error->resume; |
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94 | } |
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95 | } while (1); |
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96 | }, $class; |
230 | }, $class; |
97 | } |
231 | } |
98 | |
232 | |
99 | =item $coro->resume |
233 | =item $process->ready |
100 | |
234 | |
101 | Resume execution at the given coroutine. |
235 | Put the given process into the ready queue. |
102 | |
236 | |
103 | =cut |
237 | =cut |
104 | |
238 | |
105 | my $prev; |
239 | =item $process->cancel |
106 | |
240 | |
107 | # I call the _transfer function from a pelr function |
241 | Like C<terminate>, but terminates the specified process instead. |
108 | # because that way perl saves all important things on |
242 | |
109 | # the stack. |
243 | =cut |
110 | sub resume { |
244 | |
111 | $prev = $current; $current = $_[0]; |
245 | sub cancel { |
112 | _transfer($prev, $current); |
246 | push @destroy, $_[0]; |
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247 | $manager->ready; |
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248 | &schedule if $current == $_[0]; |
113 | } |
249 | } |
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250 | |
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251 | =item $process->join |
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252 | |
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253 | Wait until the coroutine terminates and return any values given to the |
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254 | C<terminate> function. C<join> can be called multiple times from multiple |
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255 | processes. |
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256 | |
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257 | =cut |
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258 | |
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259 | sub join { |
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260 | my $self = shift; |
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261 | unless ($self->{status}) { |
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262 | push @{$self->{join}}, $current; |
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263 | &schedule; |
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264 | } |
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265 | wantarray ? @{$self->{status}} : $self->{status}[0]; |
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266 | } |
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267 | |
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268 | =item $oldprio = $process->prio($newprio) |
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269 | |
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270 | Sets (or gets, if the argument is missing) the priority of the |
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271 | process. Higher priority processes get run before lower priority |
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272 | processes. Priorities are smalled signed integer (currently -4 .. +3), |
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273 | that you can refer to using PRIO_xxx constants (use the import tag :prio |
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274 | to get then): |
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275 | |
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276 | PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN |
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277 | 3 > 1 > 0 > -1 > -3 > -4 |
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278 | |
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279 | # set priority to HIGH |
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280 | current->prio(PRIO_HIGH); |
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281 | |
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282 | The idle coroutine ($Coro::idle) always has a lower priority than any |
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283 | existing coroutine. |
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284 | |
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285 | Changing the priority of the current process will take effect immediately, |
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286 | but changing the priority of processes in the ready queue (but not |
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287 | running) will only take effect after the next schedule (of that |
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288 | process). This is a bug that will be fixed in some future version. |
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289 | |
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290 | =cut |
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291 | |
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292 | sub prio { |
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293 | my $old = $_[0]{prio}; |
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294 | $_[0]{prio} = $_[1] if @_ > 1; |
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295 | $old; |
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296 | } |
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297 | |
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298 | =item $newprio = $process->nice($change) |
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299 | |
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300 | Similar to C<prio>, but subtract the given value from the priority (i.e. |
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301 | higher values mean lower priority, just as in unix). |
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302 | |
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303 | =cut |
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304 | |
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305 | sub nice { |
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306 | $_[0]{prio} -= $_[1]; |
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307 | } |
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308 | |
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309 | =item $olddesc = $process->desc($newdesc) |
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310 | |
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311 | Sets (or gets in case the argument is missing) the description for this |
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312 | process. This is just a free-form string you can associate with a process. |
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313 | |
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314 | =cut |
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315 | |
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316 | sub desc { |
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317 | my $old = $_[0]{desc}; |
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318 | $_[0]{desc} = $_[1] if @_ > 1; |
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319 | $old; |
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320 | } |
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321 | |
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322 | =back |
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323 | |
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324 | =cut |
114 | |
325 | |
115 | 1; |
326 | 1; |
116 | |
327 | |
117 | =back |
328 | =head1 BUGS/LIMITATIONS |
118 | |
329 | |
119 | =head1 BUGS |
330 | - you must make very sure that no coro is still active on global destruction. |
120 | |
331 | very bad things might happen otherwise (usually segfaults). |
121 | This module has not yet been extensively tested. |
332 | - this module is not thread-safe. You should only ever use this module from |
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333 | the same thread (this requirement might be loosened in the future to |
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334 | allow per-thread schedulers, but Coro::State does not yet allow this). |
122 | |
335 | |
123 | =head1 SEE ALSO |
336 | =head1 SEE ALSO |
124 | |
337 | |
125 | L<Coro::Process>, L<Coro::Signal>. |
338 | L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>, |
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339 | L<Coro::Signal>, L<Coro::State>, L<Coro::Event>, L<Coro::RWLock>, |
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340 | L<Coro::Handle>, L<Coro::Socket>. |
126 | |
341 | |
127 | =head1 AUTHOR |
342 | =head1 AUTHOR |
128 | |
343 | |
129 | Marc Lehmann <pcg@goof.com> |
344 | Marc Lehmann <pcg@goof.com> |
130 | http://www.goof.com/pcg/marc/ |
345 | http://www.goof.com/pcg/marc/ |