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 + 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 | $VERSION = 0.12; |
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42 | |
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43 | @EXPORT = qw(async cede schedule terminate current); |
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44 | @EXPORT_OK = qw($current); |
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45 | |
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46 | { |
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47 | my @async; |
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48 | |
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49 | # this way of handling attributes simply is NOT scalable ;() |
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50 | sub import { |
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51 | Coro->export_to_level(1, @_); |
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52 | my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE}; |
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53 | *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub { |
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54 | my ($package, $ref) = (shift, shift); |
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55 | my @attrs; |
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56 | for (@_) { |
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57 | if ($_ eq "Coro") { |
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58 | push @async, $ref; |
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59 | } else { |
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60 | push @attrs, $_; |
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61 | } |
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62 | } |
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63 | return $old ? $old->($package, $ref, @attrs) : @attrs; |
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64 | }; |
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65 | } |
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66 | |
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67 | sub INIT { |
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68 | &async(pop @async) while @async; |
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69 | } |
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70 | } |
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71 | |
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72 | =item $main |
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73 | |
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74 | This coroutine represents the main program. |
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75 | |
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76 | =cut |
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77 | |
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78 | our $main = new Coro; |
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79 | |
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80 | =item $current (or as function: current) |
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81 | |
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82 | The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course). |
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83 | |
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84 | =cut |
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85 | |
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86 | # maybe some other module used Coro::Specific before... |
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87 | if ($current) { |
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88 | $main->{specific} = $current->{specific}; |
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89 | } |
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90 | |
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91 | our $current = $main; |
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92 | |
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93 | sub current() { $current } |
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94 | |
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95 | =item $idle |
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96 | |
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97 | The coroutine to switch to when no other coroutine is running. The default |
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98 | implementation prints "FATAL: deadlock detected" and exits. |
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99 | |
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100 | =cut |
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101 | |
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102 | # should be done using priorities :( |
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103 | our $idle = new Coro sub { |
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104 | print STDERR "FATAL: deadlock detected\n"; |
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105 | exit(51); |
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106 | }; |
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107 | |
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108 | # this coroutine is necessary because a coroutine |
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109 | # cannot destroy itself. |
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110 | my @destroy; |
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111 | my $manager = new Coro sub { |
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112 | while() { |
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113 | delete ((pop @destroy)->{_coro_state}) while @destroy; |
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114 | &schedule; |
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115 | } |
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116 | }; |
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117 | |
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118 | # we really need priorities... |
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119 | my @ready; # the ready queue. hehe, rather broken ;) |
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120 | |
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121 | # static methods. not really. |
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122 | |
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123 | =head2 STATIC METHODS |
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124 | |
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125 | Static methods are actually functions that operate on the current process only. |
32 | |
126 | |
33 | =over 4 |
127 | =over 4 |
34 | |
128 | |
35 | =cut |
129 | =item async { ... } [@args...] |
36 | |
130 | |
37 | package Coro; |
131 | Create a new asynchronous process and return it's process object |
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132 | (usually unused). When the sub returns the new process is automatically |
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133 | terminated. |
38 | |
134 | |
39 | BEGIN { |
135 | # create a new coroutine that just prints its arguments |
40 | $VERSION = 0.03; |
136 | async { |
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137 | print "@_\n"; |
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138 | } 1,2,3,4; |
41 | |
139 | |
42 | require XSLoader; |
140 | The coderef you submit MUST NOT be a closure that refers to variables |
43 | XSLoader::load Coro, $VERSION; |
141 | in an outer scope. This does NOT work. Pass arguments into it instead. |
44 | } |
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45 | |
142 | |
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 |
143 | =cut |
55 | |
144 | |
56 | $main = $current = _newprocess { |
145 | sub async(&@) { |
57 | # never being called |
146 | my $pid = new Coro @_; |
58 | }; |
147 | $manager->ready; # this ensures that the stack is cloned from the manager |
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148 | $pid->ready; |
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149 | $pid; |
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150 | } |
59 | |
151 | |
60 | =item $error, $error_msg, $error_coro |
152 | =item schedule |
61 | |
153 | |
62 | This coroutine will be called on fatal errors. C<$error_msg> and |
154 | 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, |
155 | into the ready queue, so calling this function usually means you will |
64 | respectively. |
156 | never be called again. |
65 | |
157 | |
66 | =cut |
158 | =cut |
67 | |
159 | |
68 | $error_msg = |
160 | my $prev; |
69 | $error_coro = undef; |
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70 | |
161 | |
71 | $error = _newprocess { |
162 | sub schedule { |
72 | print STDERR "FATAL: $error_msg\nprogram aborted\n"; |
163 | # should be done using priorities :( |
73 | exit 250; |
164 | ($prev, $current) = ($current, shift @ready || $idle); |
74 | }; |
165 | Coro::State::transfer($prev, $current); |
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166 | } |
75 | |
167 | |
76 | =item $coro = new $coderef [, @args] |
168 | =item cede |
77 | |
169 | |
78 | Create a new coroutine and return it. The first C<resume> call to this |
170 | "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 |
171 | 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 |
172 | 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 | |
173 | |
83 | =cut |
174 | =cut |
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175 | |
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176 | sub cede { |
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177 | $current->ready; |
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178 | &schedule; |
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179 | } |
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180 | |
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181 | =item terminate |
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182 | |
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183 | Terminates the current process. |
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184 | |
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185 | Future versions of this function will allow result arguments. |
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186 | |
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187 | =cut |
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188 | |
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189 | sub terminate { |
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190 | push @destroy, $current; |
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191 | $manager->ready; |
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192 | &schedule; |
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193 | # NORETURN |
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194 | } |
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195 | |
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196 | =back |
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197 | |
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198 | # dynamic methods |
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199 | |
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200 | =head2 PROCESS METHODS |
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201 | |
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202 | These are the methods you can call on process objects. |
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203 | |
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204 | =over 4 |
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205 | |
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206 | =item new Coro \&sub [, @args...] |
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207 | |
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208 | Create a new process and return it. When the sub returns the process |
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209 | automatically terminates. To start the process you must first put it into |
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210 | the ready queue by calling the ready method. |
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211 | |
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212 | The coderef you submit MUST NOT be a closure that refers to variables |
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213 | in an outer scope. This does NOT work. Pass arguments into it instead. |
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214 | |
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215 | =cut |
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216 | |
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217 | sub _newcoro { |
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218 | terminate &{+shift}; |
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219 | } |
84 | |
220 | |
85 | sub new { |
221 | sub new { |
86 | my $class = $_[0]; |
222 | my $class = shift; |
87 | my $proc = $_[1]; |
223 | bless { |
88 | bless _newprocess { |
224 | _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; |
225 | }, $class; |
97 | } |
226 | } |
98 | |
227 | |
99 | =item $coro->resume |
228 | =item $process->ready |
100 | |
229 | |
101 | Resume execution at the given coroutine. |
230 | Put the current process into the ready queue. |
102 | |
231 | |
103 | =cut |
232 | =cut |
104 | |
233 | |
105 | my $prev; |
234 | sub ready { |
106 | |
235 | 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 | } |
236 | } |
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237 | |
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238 | =back |
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239 | |
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240 | =cut |
114 | |
241 | |
115 | 1; |
242 | 1; |
116 | |
243 | |
117 | =back |
244 | =head1 BUGS/LIMITATIONS |
118 | |
245 | |
119 | =head1 BUGS |
246 | - could be faster, especially when the core would introduce special |
120 | |
247 | support for coroutines (like it does for threads). |
121 | This module has not yet been extensively tested. |
248 | - there is still a memleak on coroutine termination that I could not |
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249 | identify. Could be as small as a single SV. |
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250 | - this module is not well-tested. |
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251 | - if variables or arguments "disappear" (become undef) or become |
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252 | corrupted please contact the author so he cen iron out the |
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253 | remaining bugs. |
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254 | - this module is not thread-safe. You must only ever use this module from |
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255 | the same thread (this requirement might be loosened in the future to |
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256 | allow per-thread schedulers, but Coro::State does not yet allow this). |
122 | |
257 | |
123 | =head1 SEE ALSO |
258 | =head1 SEE ALSO |
124 | |
259 | |
125 | L<Coro::Process>, L<Coro::Signal>. |
260 | L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>, |
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261 | L<Coro::Signal>, L<Coro::State>, L<Coro::Event>. |
126 | |
262 | |
127 | =head1 AUTHOR |
263 | =head1 AUTHOR |
128 | |
264 | |
129 | Marc Lehmann <pcg@goof.com> |
265 | Marc Lehmann <pcg@goof.com> |
130 | http://www.goof.com/pcg/marc/ |
266 | http://www.goof.com/pcg/marc/ |