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 | This module is still experimental, see the BUGS section below. |
30 | low-level functionality. See L<Coro::Process> and related modules for a |
27 | |
31 | more useful process abstraction including scheduling. |
28 | In this module, coroutines are defined as "callchain + lexical variables |
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29 | + @_ + $_ + $@ + $^W), that is, a coroutine has it's own callchain, it's |
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30 | own set of lexicals and it's own set of perl's most important global |
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31 | variables. |
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32 | |
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33 | WARNING: When using this module, make sure that, at program end, no |
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34 | coroutines are still running OR just call exit before falling off the |
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35 | end. The reason for this is that some coroutine of yours might have called |
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36 | into a C function, and falling off the end of main:: results in returning |
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37 | to that C function instead if to the main C interpreter. |
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38 | |
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39 | WARNING: Unless you really know what you are doing, do NOT do context |
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40 | switches inside callbacks from the XS level. The reason for this is |
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41 | similar to the reason above: A callback calls a perl function, this |
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42 | perl function does a context switch, some other callback is called, the |
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43 | original function returns from it - to what? To the wrong XS function, |
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44 | with totally different return values. Unfortunately, this includes |
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45 | callbacks done by perl itself (tie'd variables!). |
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46 | |
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47 | The only workaround for this is to do coroutines on C level. |
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48 | |
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49 | =cut |
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50 | |
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51 | package Coro; |
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52 | |
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53 | use Coro::State; |
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54 | |
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55 | use base Exporter; |
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56 | |
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57 | $VERSION = 0.10; |
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58 | |
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59 | @EXPORT = qw(async cede schedule terminate current); |
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60 | @EXPORT_OK = qw($current); |
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61 | |
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62 | { |
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63 | my @async; |
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64 | |
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65 | # this way of handling attributes simply is NOT scalable ;() |
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66 | sub import { |
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67 | Coro->export_to_level(1, @_); |
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68 | my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE}; |
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69 | *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub { |
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70 | my ($package, $ref) = (shift, shift); |
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71 | my @attrs; |
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72 | for (@_) { |
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73 | if ($_ eq "Coro") { |
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74 | push @async, $ref; |
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75 | } else { |
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76 | push @attrs, $_; |
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77 | } |
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78 | } |
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79 | return $old ? $old->($package, $ref, @attrs) : @attrs; |
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80 | }; |
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81 | } |
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82 | |
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83 | sub INIT { |
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84 | &async(pop @async) while @async; |
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85 | } |
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86 | } |
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87 | |
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88 | =item $main |
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89 | |
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90 | This coroutine represents the main program. |
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91 | |
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92 | =cut |
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93 | |
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94 | our $main = new Coro; |
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95 | |
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96 | =item $current (or as function: current) |
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97 | |
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98 | The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course). |
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99 | |
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100 | =cut |
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101 | |
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102 | # maybe some other module used Coro::Specific before... |
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103 | if ($current) { |
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104 | $main->{specific} = $current->{specific}; |
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105 | } |
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106 | |
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107 | our $current = $main; |
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108 | |
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109 | sub current() { $current } |
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110 | |
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111 | =item $idle |
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112 | |
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113 | The coroutine to switch to when no other coroutine is running. The default |
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114 | implementation prints "FATAL: deadlock detected" and exits. |
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115 | |
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116 | =cut |
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117 | |
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118 | # should be done using priorities :( |
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119 | our $idle = new Coro sub { |
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120 | print STDERR "FATAL: deadlock detected\n"; |
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121 | exit(51); |
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122 | }; |
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123 | |
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124 | # we really need priorities... |
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125 | my @ready; # the ready queue. hehe, rather broken ;) |
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126 | |
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127 | # static methods. not really. |
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128 | |
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129 | =head2 STATIC METHODS |
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130 | |
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131 | Static methods are actually functions that operate on the current process only. |
32 | |
132 | |
33 | =over 4 |
133 | =over 4 |
34 | |
134 | |
35 | =cut |
135 | =item async { ... } [@args...] |
36 | |
136 | |
37 | package Coro; |
137 | Create a new asynchronous process and return it's process object |
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138 | (usually unused). When the sub returns the new process is automatically |
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139 | terminated. |
38 | |
140 | |
39 | BEGIN { |
141 | # create a new coroutine that just prints its arguments |
40 | $VERSION = 0.03; |
142 | async { |
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143 | print "@_\n"; |
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144 | } 1,2,3,4; |
41 | |
145 | |
42 | require XSLoader; |
146 | The coderef you submit MUST NOT be a closure that refers to variables |
43 | XSLoader::load Coro, $VERSION; |
147 | in an outer scope. This does NOT work. Pass arguments into it instead. |
44 | } |
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45 | |
148 | |
46 | =item $main |
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47 | |
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48 | This coroutine represents the main program. |
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49 | |
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50 | =item $current |
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51 | |
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52 | The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course). |
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53 | |
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54 | =cut |
149 | =cut |
55 | |
150 | |
56 | $main = $current = _newprocess { |
151 | sub async(&@) { |
57 | # never being called |
152 | my $pid = new Coro @_; |
58 | }; |
153 | $pid->ready; |
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154 | $pid; |
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155 | } |
59 | |
156 | |
60 | =item $error, $error_msg, $error_coro |
157 | =item schedule |
61 | |
158 | |
62 | This coroutine will be called on fatal errors. C<$error_msg> and |
159 | Calls the scheduler. Please note that the current process will not be put |
63 | C<$error_coro> return the error message and the error-causing coroutine, |
160 | into the ready queue, so calling this function usually means you will |
64 | respectively. |
161 | never be called again. |
65 | |
162 | |
66 | =cut |
163 | =cut |
67 | |
164 | |
68 | $error_msg = |
165 | my $prev; |
69 | $error_coro = undef; |
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70 | |
166 | |
71 | $error = _newprocess { |
167 | sub schedule { |
72 | print STDERR "FATAL: $error_msg\nprogram aborted\n"; |
168 | # should be done using priorities :( |
73 | exit 250; |
169 | ($prev, $current) = ($current, shift @ready || $idle); |
74 | }; |
170 | Coro::State::transfer($prev, $current); |
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171 | } |
75 | |
172 | |
76 | =item $coro = new $coderef [, @args] |
173 | =item cede |
77 | |
174 | |
78 | Create a new coroutine and return it. The first C<resume> call to this |
175 | "Cede" to other processes. This function puts the current process into the |
79 | coroutine will start execution at the given coderef. If it returns it |
176 | ready queue and calls C<schedule>, which has the effect of giving up the |
80 | should return a coroutine to switch to. If, after returning, the coroutine |
177 | current "timeslice" to other coroutines of the same or higher priority. |
81 | is C<resume>d again it starts execution again at the givne coderef. |
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82 | |
178 | |
83 | =cut |
179 | =cut |
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180 | |
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181 | sub cede { |
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182 | $current->ready; |
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183 | &schedule; |
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184 | } |
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185 | |
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186 | =item terminate |
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187 | |
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188 | Terminates the current process. |
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189 | |
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190 | Future versions of this function will allow result arguments. |
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191 | |
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192 | =cut |
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193 | |
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194 | sub terminate { |
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195 | my $self = $current; |
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196 | $self->{_results} = [@_]; |
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197 | $current = shift @ready || $idle; |
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198 | Coro::State::transfer(delete $self->{_coro_state}, $current); |
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199 | # cannot return |
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200 | die; |
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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. To start the process you must first put it into |
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217 | the ready queue by calling the ready method. |
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218 | |
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219 | The coderef you submit MUST NOT be a closure that refers to variables |
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220 | in an outer scope. This does NOT work. Pass arguments into it instead. |
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221 | |
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222 | =cut |
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223 | |
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224 | sub _newcoro { |
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225 | terminate &{+shift}; |
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226 | } |
84 | |
227 | |
85 | sub new { |
228 | sub new { |
86 | my $class = $_[0]; |
229 | my $class = shift; |
87 | my $proc = $_[1]; |
230 | bless { |
88 | bless _newprocess { |
231 | _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; |
232 | }, $class; |
97 | } |
233 | } |
98 | |
234 | |
99 | =item $coro->resume |
235 | =item $process->ready |
100 | |
236 | |
101 | Resume execution at the given coroutine. |
237 | Put the current process into the ready queue. |
102 | |
238 | |
103 | =cut |
239 | =cut |
104 | |
240 | |
105 | my $prev; |
241 | sub ready { |
106 | |
242 | push @ready, $_[0]; |
107 | # I call the _transfer function from a pelr function |
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108 | # because that way perl saves all important things on |
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109 | # the stack. |
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110 | sub resume { |
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111 | $prev = $current; $current = $_[0]; |
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112 | _transfer($prev, $current); |
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113 | } |
243 | } |
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244 | |
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245 | =back |
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246 | |
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247 | =cut |
114 | |
248 | |
115 | 1; |
249 | 1; |
116 | |
250 | |
117 | =back |
251 | =head1 BUGS/LIMITATIONS |
118 | |
252 | |
119 | =head1 BUGS |
253 | - could be faster, especially when the core would introduce special |
120 | |
254 | support for coroutines (like it does for threads). |
121 | This module has not yet been extensively tested. |
255 | - there is still a memleak on coroutine termination that I could not |
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256 | identify. Could be as small as a single SV. |
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257 | - this module is not well-tested. |
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258 | - if variables or arguments "disappear" (become undef) or become |
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259 | corrupted please contact the author so he cen iron out the |
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260 | remaining bugs. |
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261 | - this module is not thread-safe. You must only ever use this module from |
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262 | the same thread (this requirement might be loosened in the future to |
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263 | allow per-thread schedulers, but Coro::State does not yet allow this). |
122 | |
264 | |
123 | =head1 SEE ALSO |
265 | =head1 SEE ALSO |
124 | |
266 | |
125 | L<Coro::Process>, L<Coro::Signal>. |
267 | L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>, |
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268 | L<Coro::Signal>, L<Coro::State>, L<Coro::Event>. |
126 | |
269 | |
127 | =head1 AUTHOR |
270 | =head1 AUTHOR |
128 | |
271 | |
129 | Marc Lehmann <pcg@goof.com> |
272 | Marc Lehmann <pcg@goof.com> |
130 | http://www.goof.com/pcg/marc/ |
273 | http://www.goof.com/pcg/marc/ |