1 | =head1 NAME |
1 | =head1 NAME |
2 | |
2 | |
3 | Coro - create and manage simple 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 | $new->transfer($main); |
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12 | print "in coroutine again, switching back\n"; |
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13 | $new->transfer($main); |
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14 | }; |
11 | }; |
15 | |
12 | |
16 | $main = new Coro; |
13 | # alternatively create an async process like this: |
17 | |
14 | |
18 | print "in main, switching to coroutine\n"; |
15 | sub some_func : Coro { |
19 | $main->transfer($new); |
16 | # some more async code |
20 | print "back in main, switch to coroutine again\n"; |
17 | } |
21 | $main->transfer($new); |
18 | |
22 | print "back in main\n"; |
19 | cede; |
23 | |
20 | |
24 | =head1 DESCRIPTION |
21 | =head1 DESCRIPTION |
25 | |
22 | |
26 | This module implements coroutines. Coroutines, similar to continuations, |
23 | This module collection manages coroutines. Coroutines are similar to |
27 | allow you to run more than one "thread of execution" in parallel. Unlike |
24 | Threads but don't run in parallel. |
28 | threads this, only voluntary switching is used so locking problems are |
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29 | greatly reduced. |
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30 | |
25 | |
31 | Although this is the "main" module of the Coro family it provides only |
26 | This module is still experimental, see the BUGS section below. |
32 | low-level functionality. See L<Coro::Process> and related modules for a |
27 | |
33 | more useful process abstraction including scheduling. |
28 | In this module, coroutines are defined as "callchain + lexical variables |
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29 | + @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own |
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30 | callchain, it's own set of lexicals and it's own set of perl's most |
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31 | important global variables. |
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32 | |
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33 | =cut |
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34 | |
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35 | package Coro; |
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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 | $VERSION = 0.45; |
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42 | |
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43 | @EXPORT = qw(async cede schedule terminate current); |
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44 | %EXPORT_TAGS = ( |
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45 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
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46 | ); |
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47 | @EXPORT_OK = @{$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 | } |
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79 | |
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80 | =item $main |
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81 | |
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82 | This coroutine represents the main program. |
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83 | |
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84 | =cut |
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85 | |
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86 | our $main = new Coro; |
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87 | |
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88 | =item $current (or as function: current) |
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89 | |
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90 | The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course). |
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91 | |
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92 | =cut |
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93 | |
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94 | # maybe some other module used Coro::Specific before... |
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95 | if ($current) { |
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96 | $main->{specific} = $current->{specific}; |
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97 | } |
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98 | |
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99 | our $current = $main; |
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100 | |
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101 | sub current() { $current } |
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102 | |
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103 | =item $idle |
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104 | |
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105 | The coroutine to switch to when no other coroutine is running. The default |
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106 | implementation prints "FATAL: deadlock detected" and exits. |
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107 | |
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108 | =cut |
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109 | |
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110 | # should be done using priorities :( |
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111 | our $idle = new Coro sub { |
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112 | print STDERR "FATAL: deadlock detected\n"; |
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113 | exit(51); |
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114 | }; |
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115 | |
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116 | # this coroutine is necessary because a coroutine |
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117 | # cannot destroy itself. |
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118 | my @destroy; |
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119 | my $manager = new Coro sub { |
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120 | while() { |
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121 | delete ((pop @destroy)->{_coro_state}) while @destroy; |
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122 | &schedule; |
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123 | } |
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124 | }; |
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125 | |
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126 | # static methods. not really. |
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127 | |
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128 | =head2 STATIC METHODS |
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129 | |
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130 | Static methods are actually functions that operate on the current process only. |
34 | |
131 | |
35 | =over 4 |
132 | =over 4 |
36 | |
133 | |
37 | =cut |
134 | =item async { ... } [@args...] |
38 | |
135 | |
39 | package Coro; |
136 | Create a new asynchronous process and return it's process object |
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137 | (usually unused). When the sub returns the new process is automatically |
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138 | terminated. |
40 | |
139 | |
41 | BEGIN { |
140 | # create a new coroutine that just prints its arguments |
42 | $VERSION = 0.03; |
141 | async { |
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142 | print "@_\n"; |
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143 | } 1,2,3,4; |
43 | |
144 | |
44 | require XSLoader; |
145 | The coderef you submit MUST NOT be a closure that refers to variables |
45 | XSLoader::load Coro, $VERSION; |
146 | in an outer scope. This does NOT work. Pass arguments into it instead. |
46 | } |
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47 | |
147 | |
48 | =item $coro = new [$coderef [, @args]] |
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49 | |
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50 | Create a new coroutine and return it. The first C<transfer> call to this |
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51 | coroutine will start execution at the given coderef. If, the subroutine |
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52 | returns it will be executed again. |
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53 | |
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54 | If the coderef is omitted this function will create a new "empty" |
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55 | coroutine, i.e. a coroutine that cannot be transfered to but can be used |
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56 | to save the current coroutine in. |
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57 | |
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58 | =cut |
148 | =cut |
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149 | |
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150 | sub async(&@) { |
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151 | my $pid = new Coro @_; |
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152 | $manager->ready; # this ensures that the stack is cloned from the manager |
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153 | $pid->ready; |
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154 | $pid; |
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155 | } |
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156 | |
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157 | =item schedule |
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158 | |
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159 | Calls the scheduler. Please note that the current process will not be put |
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160 | into the ready queue, so calling this function usually means you will |
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161 | never be called again. |
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162 | |
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163 | =cut |
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164 | |
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165 | =item cede |
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166 | |
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167 | "Cede" to other processes. This function puts the current process into the |
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168 | ready queue and calls C<schedule>, which has the effect of giving up the |
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169 | current "timeslice" to other coroutines of the same or higher priority. |
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170 | |
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171 | =cut |
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172 | |
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173 | =item terminate |
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174 | |
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175 | Terminates the current process. |
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176 | |
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177 | Future versions of this function will allow result arguments. |
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178 | |
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179 | =cut |
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180 | |
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181 | sub terminate { |
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182 | $current->cancel; |
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183 | &schedule; |
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184 | die; # NORETURN |
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185 | } |
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186 | |
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187 | =back |
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188 | |
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189 | # dynamic methods |
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190 | |
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191 | =head2 PROCESS METHODS |
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192 | |
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193 | These are the methods you can call on process objects. |
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194 | |
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195 | =over 4 |
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196 | |
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197 | =item new Coro \&sub [, @args...] |
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198 | |
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199 | Create a new process and return it. When the sub returns the process |
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200 | automatically terminates. To start the process you must first put it into |
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201 | the ready queue by calling the ready method. |
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202 | |
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203 | The coderef you submit MUST NOT be a closure that refers to variables |
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204 | in an outer scope. This does NOT work. Pass arguments into it instead. |
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205 | |
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206 | =cut |
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207 | |
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208 | sub _newcoro { |
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209 | terminate &{+shift}; |
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210 | } |
59 | |
211 | |
60 | sub new { |
212 | sub new { |
61 | my $class = $_[0]; |
213 | my $class = shift; |
62 | my $proc = $_[1] || sub { die "tried to transfer to an empty coroutine" }; |
214 | bless { |
63 | bless _newprocess { |
215 | _coro_state => (new Coro::State $_[0] && \&_newcoro, @_), |
64 | do { |
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65 | eval { &$proc }; |
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66 | if ($@) { |
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67 | $error_msg = $@; |
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68 | $error_coro = _newprocess { }; |
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69 | &transfer($error_coro, $error); |
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70 | } |
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71 | } while (1); |
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72 | }, $class; |
216 | }, $class; |
73 | } |
217 | } |
74 | |
218 | |
75 | =item $prev->transfer($next) |
219 | =item $process->ready |
76 | |
220 | |
77 | Save the state of the current subroutine in $prev and switch to the |
221 | Put the current process into the ready queue. |
78 | coroutine saved in $next. |
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79 | |
222 | |
80 | =cut |
223 | =cut |
81 | |
224 | |
82 | # I call the _transfer function from a perl function |
225 | =item $process->cancel |
83 | # because that way perl saves all important things on |
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84 | # the stack. |
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85 | sub transfer { |
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86 | _transfer($_[0], $_[1]); |
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87 | } |
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88 | |
226 | |
89 | =item $error, $error_msg, $error_coro |
227 | Like C<terminate>, but terminates the specified process instead. |
90 | |
228 | |
91 | This coroutine will be called on fatal errors. C<$error_msg> and |
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92 | C<$error_coro> return the error message and the error-causing coroutine |
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93 | (NOT an object) respectively. This API might change. |
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94 | |
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95 | =cut |
229 | =cut |
96 | |
230 | |
97 | $error_msg = |
231 | sub cancel { |
98 | $error_coro = undef; |
232 | push @destroy, $_[0]; |
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233 | $manager->ready; |
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234 | } |
99 | |
235 | |
100 | $error = _newprocess { |
236 | =item $oldprio = $process->prio($newprio) |
101 | print STDERR "FATAL: $error_msg\nprogram aborted\n"; |
237 | |
102 | exit 50; |
238 | Sets the priority of the process. Higher priority processes get run before |
103 | }; |
239 | lower priority processes. Priorities are smalled signed integer (currently |
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240 | -4 .. +3), that you can refer to using PRIO_xxx constants (use the import |
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241 | tag :prio to get then): |
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242 | |
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243 | PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN |
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244 | 3 > 1 > 0 > -1 > -3 > -4 |
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245 | |
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246 | # set priority to HIGH |
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247 | current->prio(PRIO_HIGH); |
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248 | |
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249 | The idle coroutine ($Coro::idle) always has a lower priority than any |
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250 | existing coroutine. |
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251 | |
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252 | Changing the priority of the current process will take effect immediately, |
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253 | but changing the priority of processes in the ready queue (but not |
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254 | running) will only take effect after the next schedule (of that |
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255 | process). This is a bug that will be fixed in some future version. |
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256 | |
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257 | =cut |
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258 | |
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259 | sub prio { |
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260 | my $old = $_[0]{prio}; |
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261 | $_[0]{prio} = $_[1] if @_ > 1; |
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262 | $old; |
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263 | } |
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264 | |
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265 | =item $newprio = $process->nice($change) |
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266 | |
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267 | Similar to C<prio>, but subtract the given value from the priority (i.e. |
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268 | higher values mean lower priority, just as in unix). |
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269 | |
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270 | =cut |
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271 | |
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272 | sub nice { |
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273 | $_[0]{prio} -= $_[1]; |
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274 | } |
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275 | |
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276 | =back |
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277 | |
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278 | =cut |
104 | |
279 | |
105 | 1; |
280 | 1; |
106 | |
281 | |
107 | =back |
282 | =head1 BUGS/LIMITATIONS |
108 | |
283 | |
109 | =head1 BUGS |
284 | - could be faster, especially when the core would introduce special |
110 | |
285 | support for coroutines (like it does for threads). |
111 | This module has not yet been extensively tested. |
286 | - there is still a memleak on coroutine termination that I could not |
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287 | identify. Could be as small as a single SV. |
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288 | - this module is not well-tested. |
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289 | - if variables or arguments "disappear" (become undef) or become |
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290 | corrupted please contact the author so he cen iron out the |
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291 | remaining bugs. |
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292 | - this module is not thread-safe. You must only ever use this module from |
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293 | the same thread (this requirement might be loosened in the future to |
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294 | allow per-thread schedulers, but Coro::State does not yet allow this). |
112 | |
295 | |
113 | =head1 SEE ALSO |
296 | =head1 SEE ALSO |
114 | |
297 | |
115 | L<Coro::Process>, L<Coro::Signal>. |
298 | L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>, |
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299 | L<Coro::Signal>, L<Coro::State>, L<Coro::Event>, L<Coro::RWLock>, |
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300 | L<Coro::Handle>, L<Coro::Socket>. |
116 | |
301 | |
117 | =head1 AUTHOR |
302 | =head1 AUTHOR |
118 | |
303 | |
119 | Marc Lehmann <pcg@goof.com> |
304 | Marc Lehmann <pcg@goof.com> |
120 | http://www.goof.com/pcg/marc/ |
305 | http://www.goof.com/pcg/marc/ |