… | |
… | |
11 | print "2\n"; |
11 | print "2\n"; |
12 | cede; # yield back to main |
12 | cede; # yield back to main |
13 | print "4\n"; |
13 | print "4\n"; |
14 | }; |
14 | }; |
15 | print "1\n"; |
15 | print "1\n"; |
16 | cede; # yield to coroutine |
16 | cede; # yield to coro |
17 | print "3\n"; |
17 | print "3\n"; |
18 | cede; # and again |
18 | cede; # and again |
19 | |
19 | |
20 | # use locking |
20 | # use locking |
21 | use Coro::Semaphore; |
21 | use Coro::Semaphore; |
… | |
… | |
29 | =head1 DESCRIPTION |
29 | =head1 DESCRIPTION |
30 | |
30 | |
31 | For a tutorial-style introduction, please read the L<Coro::Intro> |
31 | For a tutorial-style introduction, please read the L<Coro::Intro> |
32 | manpage. This manpage mainly contains reference information. |
32 | manpage. This manpage mainly contains reference information. |
33 | |
33 | |
34 | This module collection manages continuations in general, most often |
34 | This module collection manages continuations in general, most often in |
35 | in the form of cooperative threads (also called coroutines in the |
35 | the form of cooperative threads (also called coros, or simply "coro" |
36 | documentation). They are similar to kernel threads but don't (in general) |
36 | in the documentation). They are similar to kernel threads but don't (in |
37 | run in parallel at the same time even on SMP machines. The specific flavor |
37 | general) run in parallel at the same time even on SMP machines. The |
38 | of thread offered by this module also guarantees you that it will not |
38 | specific flavor of thread offered by this module also guarantees you that |
39 | switch between threads unless necessary, at easily-identified points in |
39 | it will not switch between threads unless necessary, at easily-identified |
40 | your program, so locking and parallel access are rarely an issue, making |
40 | points in your program, so locking and parallel access are rarely an |
41 | thread programming much safer and easier than using other thread models. |
41 | issue, making thread programming much safer and easier than using other |
|
|
42 | thread models. |
42 | |
43 | |
43 | Unlike the so-called "Perl threads" (which are not actually real threads |
44 | Unlike the so-called "Perl threads" (which are not actually real threads |
44 | but only the windows process emulation ported to unix), Coro provides a |
45 | but only the windows process emulation (see section of same name for |
|
|
46 | more details) ported to UNIX, and as such act as processes), Coro |
45 | full shared address space, which makes communication between threads |
47 | provides a full shared address space, which makes communication between |
46 | very easy. And threads are fast, too: disabling the Windows process |
48 | threads very easy. And coro threads are fast, too: disabling the Windows |
47 | emulation code in your perl and using Coro can easily result in a two to |
49 | process emulation code in your perl and using Coro can easily result in |
48 | four times speed increase for your programs. |
50 | a two to four times speed increase for your programs. A parallel matrix |
|
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51 | multiplication benchmark (very communication-intensive) runs over 300 |
|
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52 | times faster on a single core than perls pseudo-threads on a quad core |
|
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53 | using all four cores. |
49 | |
54 | |
50 | Coro achieves that by supporting multiple running interpreters that share |
55 | Coro achieves that by supporting multiple running interpreters that share |
51 | data, which is especially useful to code pseudo-parallel processes and |
56 | data, which is especially useful to code pseudo-parallel processes and |
52 | for event-based programming, such as multiple HTTP-GET requests running |
57 | for event-based programming, such as multiple HTTP-GET requests running |
53 | concurrently. See L<Coro::AnyEvent> to learn more on how to integrate Coro |
58 | concurrently. See L<Coro::AnyEvent> to learn more on how to integrate Coro |
54 | into an event-based environment. |
59 | into an event-based environment. |
55 | |
60 | |
56 | In this module, a thread is defined as "callchain + lexical variables + |
61 | In this module, a thread is defined as "callchain + lexical variables + |
57 | @_ + $_ + $@ + $/ + C stack), that is, a thread has its own callchain, |
62 | some package variables + C stack), that is, a thread has its own callchain, |
58 | its own set of lexicals and its own set of perls most important global |
63 | its own set of lexicals and its own set of perls most important global |
59 | variables (see L<Coro::State> for more configuration and background info). |
64 | variables (see L<Coro::State> for more configuration and background info). |
60 | |
65 | |
61 | See also the C<SEE ALSO> section at the end of this document - the Coro |
66 | See also the C<SEE ALSO> section at the end of this document - the Coro |
62 | module family is quite large. |
67 | module family is quite large. |
63 | |
68 | |
|
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69 | =head1 CORO THREAD LIFE CYCLE |
|
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70 | |
|
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71 | During the long and exciting (or not) life of a coro thread, it goes |
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72 | through a number of states: |
|
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73 | |
|
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74 | =over 4 |
|
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75 | |
|
|
76 | =item 1. Creation |
|
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77 | |
|
|
78 | The first thing in the life of a coro thread is it's creation - |
|
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79 | obviously. The typical way to create a thread is to call the C<async |
|
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80 | BLOCK> function: |
|
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81 | |
|
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82 | async { |
|
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83 | # thread code goes here |
|
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84 | }; |
|
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85 | |
|
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86 | You can also pass arguments, which are put in C<@_>: |
|
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87 | |
|
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88 | async { |
|
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89 | print $_[1]; # prints 2 |
|
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90 | } 1, 2, 3; |
|
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91 | |
|
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92 | This creates a new coro thread and puts it into the ready queue, meaning |
|
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93 | it will run as soon as the CPU is free for it. |
|
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94 | |
|
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95 | C<async> will return a coro object - you can store this for future |
|
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96 | reference or ignore it, the thread itself will keep a reference to it's |
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97 | thread object - threads are alive on their own. |
|
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98 | |
|
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99 | Another way to create a thread is to call the C<new> constructor with a |
|
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100 | code-reference: |
|
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101 | |
|
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102 | new Coro sub { |
|
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103 | # thread code goes here |
|
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104 | }, @optional_arguments; |
|
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105 | |
|
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106 | This is quite similar to calling C<async>, but the important difference is |
|
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107 | that the new thread is not put into the ready queue, so the thread will |
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108 | not run until somebody puts it there. C<async> is, therefore, identical to |
|
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109 | this sequence: |
|
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110 | |
|
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111 | my $coro = new Coro sub { |
|
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112 | # thread code goes here |
|
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113 | }; |
|
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114 | $coro->ready; |
|
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115 | return $coro; |
|
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116 | |
|
|
117 | =item 2. Startup |
|
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118 | |
|
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119 | When a new coro thread is created, only a copy of the code reference |
|
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120 | and the arguments are stored, no extra memory for stacks and so on is |
|
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121 | allocated, keeping the coro thread in a low-memory state. |
|
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122 | |
|
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123 | Only when it actually starts executing will all the resources be finally |
|
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124 | allocated. |
|
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125 | |
|
|
126 | The optional arguments specified at coro creation are available in C<@_>, |
|
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127 | similar to function calls. |
|
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128 | |
|
|
129 | =item 3. Running / Blocking |
|
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130 | |
|
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131 | A lot can happen after the coro thread has started running. Quite usually, |
|
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132 | it will not run to the end in one go (because you could use a function |
|
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133 | instead), but it will give up the CPU regularly because it waits for |
|
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134 | external events. |
|
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135 | |
|
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136 | As long as a coro thread runs, it's coro object is available in the global |
|
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137 | variable C<$Coro::current>. |
|
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138 | |
|
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139 | The low-level way to give up the CPU is to call the scheduler, which |
|
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140 | selects a new coro thread to run: |
|
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141 | |
|
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142 | Coro::schedule; |
|
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143 | |
|
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144 | Since running threads are not in the ready queue, calling the scheduler |
|
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145 | without doing anything else will block the coro thread forever - you need |
|
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146 | to arrange either for the coro to put woken up (readied) by some other |
|
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147 | event or some other thread, or you can put it into the ready queue before |
|
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148 | scheduling: |
|
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149 | |
|
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150 | # this is exactly what Coro::cede does |
|
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151 | $Coro::current->ready; |
|
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152 | Coro::schedule; |
|
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153 | |
|
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154 | All the higher-level synchronisation methods (Coro::Semaphore, |
|
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155 | Coro::rouse_*...) are actually implemented via C<< ->ready >> and C<< |
|
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156 | Coro::schedule >>. |
|
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157 | |
|
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158 | While the coro thread is running it also might get assigned a C-level |
|
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159 | thread, or the C-level thread might be unassigned from it, as the Coro |
|
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160 | runtime wishes. A C-level thread needs to be assigned when your perl |
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161 | thread calls into some C-level function and that function in turn calls |
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162 | perl and perl then wants to switch coroutines. This happens most often |
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163 | when you run an event loop and block in the callback, or when perl |
|
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164 | itself calls some function such as C<AUTOLOAD> or methods via the C<tie> |
|
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165 | mechanism. |
|
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166 | |
|
|
167 | =item 4. Termination |
|
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168 | |
|
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169 | Many threads actually terminate after some time. There are a number of |
|
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170 | ways to terminate a coro thread, the simplest is returning from the |
|
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171 | top-level code reference: |
|
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172 | |
|
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173 | async { |
|
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174 | # after returning from here, the coro thread is terminated |
|
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175 | }; |
|
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176 | |
|
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177 | async { |
|
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178 | return if 0.5 < rand; # terminate a little earlier, maybe |
|
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179 | print "got a chance to print this\n"; |
|
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180 | # or here |
|
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181 | }; |
|
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182 | |
|
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183 | Any values returned from the coroutine can be recovered using C<< ->join |
|
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184 | >>: |
|
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185 | |
|
|
186 | my $coro = async { |
|
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187 | "hello, world\n" # return a string |
|
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188 | }; |
|
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189 | |
|
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190 | my $hello_world = $coro->join; |
|
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191 | |
|
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192 | print $hello_world; |
|
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193 | |
|
|
194 | Another way to terminate is to call C<< Coro::terminate >>, which at any |
|
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195 | subroutine call nesting level: |
|
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196 | |
|
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197 | async { |
|
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198 | Coro::terminate "return value 1", "return value 2"; |
|
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199 | }; |
|
|
200 | |
|
|
201 | And yet another way is to C<< ->cancel >> the coro thread from another |
|
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202 | thread: |
|
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203 | |
|
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204 | my $coro = async { |
|
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205 | exit 1; |
|
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206 | }; |
|
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207 | |
|
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208 | $coro->cancel; # an also accept values for ->join to retrieve |
|
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209 | |
|
|
210 | Cancellation I<can> be dangerous - it's a bit like calling C<exit> without |
|
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211 | actually exiting, and might leave C libraries and XS modules in a weird |
|
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212 | state. Unlike other thread implementations, however, Coro is exceptionally |
|
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213 | safe with regards to cancellation, as perl will always be in a consistent |
|
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214 | state. |
|
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215 | |
|
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216 | So, cancelling a thread that runs in an XS event loop might not be the |
|
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217 | best idea, but any other combination that deals with perl only (cancelling |
|
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218 | when a thread is in a C<tie> method or an C<AUTOLOAD> for example) is |
|
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219 | safe. |
|
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220 | |
|
|
221 | =item 5. Cleanup |
|
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222 | |
|
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223 | Threads will allocate various resources. Most but not all will be returned |
|
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224 | when a thread terminates, during clean-up. |
|
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225 | |
|
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226 | Cleanup is quite similar to throwing an uncaught exception: perl will |
|
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227 | work it's way up through all subroutine calls and blocks. On it's way, it |
|
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228 | will release all C<my> variables, undo all C<local>'s and free any other |
|
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229 | resources truly local to the thread. |
|
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230 | |
|
|
231 | So, a common way to free resources is to keep them referenced only by my |
|
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232 | variables: |
|
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233 | |
|
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234 | async { |
|
|
235 | my $big_cache = new Cache ...; |
|
|
236 | }; |
|
|
237 | |
|
|
238 | If there are no other references, then the C<$big_cache> object will be |
|
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239 | freed when the thread terminates, regardless of how it does so. |
|
|
240 | |
|
|
241 | What it does C<NOT> do is unlock any Coro::Semaphores or similar |
|
|
242 | resources, but that's where the C<guard> methods come in handy: |
|
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243 | |
|
|
244 | my $sem = new Coro::Semaphore; |
|
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245 | |
|
|
246 | async { |
|
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247 | my $lock_guard = $sem->guard; |
|
|
248 | # if we reutrn, or die or get cancelled, here, |
|
|
249 | # then the semaphore will be "up"ed. |
|
|
250 | }; |
|
|
251 | |
|
|
252 | The C<Guard::guard> function comes in handy for any custom cleanup you |
|
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253 | might want to do: |
|
|
254 | |
|
|
255 | async { |
|
|
256 | my $window = new Gtk2::Window "toplevel"; |
|
|
257 | # The window will not be cleaned up automatically, even when $window |
|
|
258 | # gets freed, so use a guard to ensure it's destruction |
|
|
259 | # in case of an error: |
|
|
260 | my $window_guard = Guard::guard { $window->destroy }; |
|
|
261 | |
|
|
262 | # we are safe here |
|
|
263 | }; |
|
|
264 | |
|
|
265 | Last not least, C<local> can often be handy, too, e.g. when temporarily |
|
|
266 | replacing the coro thread description: |
|
|
267 | |
|
|
268 | sub myfunction { |
|
|
269 | local $Coro::current->{desc} = "inside myfunction(@_)"; |
|
|
270 | |
|
|
271 | # if we return or die here, the description will be restored |
|
|
272 | } |
|
|
273 | |
|
|
274 | =item 6. Viva La Zombie Muerte |
|
|
275 | |
|
|
276 | Even after a thread has terminated and cleaned up it's resources, the coro |
|
|
277 | object still is there and stores the return values of the thread. Only in |
|
|
278 | this state will the coro object be "reference counted" in the normal perl |
|
|
279 | sense: the thread code keeps a reference to it when it is active, but not |
|
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280 | after it has terminated. |
|
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281 | |
|
|
282 | The means the coro object gets freed automatically when the thread has |
|
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283 | terminated and cleaned up and there arenot other references. |
|
|
284 | |
|
|
285 | If there are, the coro object will stay around, and you can call C<< |
|
|
286 | ->join >> as many times as you wish to retrieve the result values: |
|
|
287 | |
|
|
288 | async { |
|
|
289 | print "hi\n"; |
|
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290 | 1 |
|
|
291 | }; |
|
|
292 | |
|
|
293 | # run the async above, and free everything before returning |
|
|
294 | # from Coro::cede: |
|
|
295 | Coro::cede; |
|
|
296 | |
|
|
297 | { |
|
|
298 | my $coro = async { |
|
|
299 | print "hi\n"; |
|
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300 | 1 |
|
|
301 | }; |
|
|
302 | |
|
|
303 | # run the async above, and clean up, but do not free the coro |
|
|
304 | # object: |
|
|
305 | Coro::cede; |
|
|
306 | |
|
|
307 | # optionally retrieve the result values |
|
|
308 | my @results = $coro->join; |
|
|
309 | |
|
|
310 | # now $coro goes out of scope, and presumably gets freed |
|
|
311 | }; |
|
|
312 | |
|
|
313 | =back |
|
|
314 | |
64 | =cut |
315 | =cut |
65 | |
316 | |
66 | package Coro; |
317 | package Coro; |
67 | |
318 | |
68 | use strict qw(vars subs); |
319 | use common::sense; |
69 | no warnings "uninitialized"; |
320 | |
|
|
321 | use Carp (); |
|
|
322 | |
|
|
323 | use Guard (); |
70 | |
324 | |
71 | use Coro::State; |
325 | use Coro::State; |
72 | |
326 | |
73 | use base qw(Coro::State Exporter); |
327 | use base qw(Coro::State Exporter); |
74 | |
328 | |
75 | our $idle; # idle handler |
329 | our $idle; # idle handler |
76 | our $main; # main coroutine |
330 | our $main; # main coro |
77 | our $current; # current coroutine |
331 | our $current; # current coro |
78 | |
332 | |
79 | our $VERSION = 5.13; |
333 | our $VERSION = 5.371; |
80 | |
334 | |
81 | our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); |
335 | our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub rouse_cb rouse_wait); |
82 | our %EXPORT_TAGS = ( |
336 | our %EXPORT_TAGS = ( |
83 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
337 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
84 | ); |
338 | ); |
85 | our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready)); |
339 | our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready)); |
86 | |
340 | |
… | |
… | |
88 | |
342 | |
89 | =over 4 |
343 | =over 4 |
90 | |
344 | |
91 | =item $Coro::main |
345 | =item $Coro::main |
92 | |
346 | |
93 | This variable stores the coroutine object that represents the main |
347 | This variable stores the Coro object that represents the main |
94 | program. While you cna C<ready> it and do most other things you can do to |
348 | program. While you cna C<ready> it and do most other things you can do to |
95 | coroutines, it is mainly useful to compare again C<$Coro::current>, to see |
349 | coro, it is mainly useful to compare again C<$Coro::current>, to see |
96 | whether you are running in the main program or not. |
350 | whether you are running in the main program or not. |
97 | |
351 | |
98 | =cut |
352 | =cut |
99 | |
353 | |
100 | # $main is now being initialised by Coro::State |
354 | # $main is now being initialised by Coro::State |
101 | |
355 | |
102 | =item $Coro::current |
356 | =item $Coro::current |
103 | |
357 | |
104 | The coroutine object representing the current coroutine (the last |
358 | The Coro object representing the current coro (the last |
105 | coroutine that the Coro scheduler switched to). The initial value is |
359 | coro that the Coro scheduler switched to). The initial value is |
106 | C<$Coro::main> (of course). |
360 | C<$Coro::main> (of course). |
107 | |
361 | |
108 | This variable is B<strictly> I<read-only>. You can take copies of the |
362 | This variable is B<strictly> I<read-only>. You can take copies of the |
109 | value stored in it and use it as any other coroutine object, but you must |
363 | value stored in it and use it as any other Coro object, but you must |
110 | not otherwise modify the variable itself. |
364 | not otherwise modify the variable itself. |
111 | |
365 | |
112 | =cut |
366 | =cut |
113 | |
367 | |
114 | sub current() { $current } # [DEPRECATED] |
368 | sub current() { $current } # [DEPRECATED] |
… | |
… | |
117 | |
371 | |
118 | This variable is mainly useful to integrate Coro into event loops. It is |
372 | This variable is mainly useful to integrate Coro into event loops. It is |
119 | usually better to rely on L<Coro::AnyEvent> or L<Coro::EV>, as this is |
373 | usually better to rely on L<Coro::AnyEvent> or L<Coro::EV>, as this is |
120 | pretty low-level functionality. |
374 | pretty low-level functionality. |
121 | |
375 | |
122 | This variable stores either a coroutine or a callback. |
376 | This variable stores a Coro object that is put into the ready queue when |
|
|
377 | there are no other ready threads (without invoking any ready hooks). |
123 | |
378 | |
124 | If it is a callback, the it is called whenever the scheduler finds no |
379 | The default implementation dies with "FATAL: deadlock detected.", followed |
125 | ready coroutines to run. The default implementation prints "FATAL: |
380 | by a thread listing, because the program has no other way to continue. |
126 | deadlock detected" and exits, because the program has no other way to |
|
|
127 | continue. |
|
|
128 | |
|
|
129 | If it is a coroutine object, then this object will be readied (without |
|
|
130 | invoking any ready hooks, however) when the scheduler finds no other ready |
|
|
131 | coroutines to run. |
|
|
132 | |
381 | |
133 | This hook is overwritten by modules such as C<Coro::EV> and |
382 | This hook is overwritten by modules such as C<Coro::EV> and |
134 | C<Coro::AnyEvent> to wait on an external event that hopefully wake up a |
383 | C<Coro::AnyEvent> to wait on an external event that hopefully wakes up a |
135 | coroutine so the scheduler can run it. |
384 | coro so the scheduler can run it. |
136 | |
385 | |
137 | Note that the callback I<must not>, under any circumstances, block |
|
|
138 | the current coroutine. Normally, this is achieved by having an "idle |
|
|
139 | coroutine" that calls the event loop and then blocks again, and then |
|
|
140 | readying that coroutine in the idle handler, or by simply placing the idle |
|
|
141 | coroutine in this variable. |
|
|
142 | |
|
|
143 | See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this |
386 | See L<Coro::EV> or L<Coro::AnyEvent> for examples of using this technique. |
144 | technique. |
|
|
145 | |
387 | |
146 | Please note that if your callback recursively invokes perl (e.g. for event |
|
|
147 | handlers), then it must be prepared to be called recursively itself. |
|
|
148 | |
|
|
149 | =cut |
388 | =cut |
150 | |
389 | |
151 | $idle = sub { |
390 | # ||= because other modules could have provided their own by now |
152 | require Carp; |
391 | $idle ||= new Coro sub { |
153 | Carp::croak ("FATAL: deadlock detected"); |
392 | require Coro::Debug; |
|
|
393 | die "FATAL: deadlock detected.\n" |
|
|
394 | . Coro::Debug::ps_listing (); |
154 | }; |
395 | }; |
155 | |
396 | |
156 | # this coroutine is necessary because a coroutine |
397 | # this coro is necessary because a coro |
157 | # cannot destroy itself. |
398 | # cannot destroy itself. |
158 | our @destroy; |
399 | our @destroy; |
159 | our $manager; |
400 | our $manager; |
160 | |
401 | |
161 | $manager = new Coro sub { |
402 | $manager = new Coro sub { |
162 | while () { |
403 | while () { |
163 | Coro::_cancel shift @destroy |
404 | Coro::State::cancel shift @destroy |
164 | while @destroy; |
405 | while @destroy; |
165 | |
406 | |
166 | &schedule; |
407 | &schedule; |
167 | } |
408 | } |
168 | }; |
409 | }; |
169 | $manager->{desc} = "[coro manager]"; |
410 | $manager->{desc} = "[coro manager]"; |
170 | $manager->prio (PRIO_MAX); |
411 | $manager->prio (PRIO_MAX); |
171 | |
412 | |
172 | =back |
413 | =back |
173 | |
414 | |
174 | =head1 SIMPLE COROUTINE CREATION |
415 | =head1 SIMPLE CORO CREATION |
175 | |
416 | |
176 | =over 4 |
417 | =over 4 |
177 | |
418 | |
178 | =item async { ... } [@args...] |
419 | =item async { ... } [@args...] |
179 | |
420 | |
180 | Create a new coroutine and return its coroutine object (usually |
421 | Create a new coro and return its Coro object (usually |
181 | unused). The coroutine will be put into the ready queue, so |
422 | unused). The coro will be put into the ready queue, so |
182 | it will start running automatically on the next scheduler run. |
423 | it will start running automatically on the next scheduler run. |
183 | |
424 | |
184 | The first argument is a codeblock/closure that should be executed in the |
425 | The first argument is a codeblock/closure that should be executed in the |
185 | coroutine. When it returns argument returns the coroutine is automatically |
426 | coro. When it returns argument returns the coro is automatically |
186 | terminated. |
427 | terminated. |
187 | |
428 | |
188 | The remaining arguments are passed as arguments to the closure. |
429 | The remaining arguments are passed as arguments to the closure. |
189 | |
430 | |
190 | See the C<Coro::State::new> constructor for info about the coroutine |
431 | See the C<Coro::State::new> constructor for info about the coro |
191 | environment in which coroutines are executed. |
432 | environment in which coro are executed. |
192 | |
433 | |
193 | Calling C<exit> in a coroutine will do the same as calling exit outside |
434 | Calling C<exit> in a coro will do the same as calling exit outside |
194 | the coroutine. Likewise, when the coroutine dies, the program will exit, |
435 | the coro. Likewise, when the coro dies, the program will exit, |
195 | just as it would in the main program. |
436 | just as it would in the main program. |
196 | |
437 | |
197 | If you do not want that, you can provide a default C<die> handler, or |
438 | If you do not want that, you can provide a default C<die> handler, or |
198 | simply avoid dieing (by use of C<eval>). |
439 | simply avoid dieing (by use of C<eval>). |
199 | |
440 | |
200 | Example: Create a new coroutine that just prints its arguments. |
441 | Example: Create a new coro that just prints its arguments. |
201 | |
442 | |
202 | async { |
443 | async { |
203 | print "@_\n"; |
444 | print "@_\n"; |
204 | } 1,2,3,4; |
445 | } 1,2,3,4; |
205 | |
446 | |
206 | =cut |
|
|
207 | |
|
|
208 | sub async(&@) { |
|
|
209 | my $coro = new Coro @_; |
|
|
210 | $coro->ready; |
|
|
211 | $coro |
|
|
212 | } |
|
|
213 | |
|
|
214 | =item async_pool { ... } [@args...] |
447 | =item async_pool { ... } [@args...] |
215 | |
448 | |
216 | Similar to C<async>, but uses a coroutine pool, so you should not call |
449 | Similar to C<async>, but uses a coro pool, so you should not call |
217 | terminate or join on it (although you are allowed to), and you get a |
450 | terminate or join on it (although you are allowed to), and you get a |
218 | coroutine that might have executed other code already (which can be good |
451 | coro that might have executed other code already (which can be good |
219 | or bad :). |
452 | or bad :). |
220 | |
453 | |
221 | On the plus side, this function is about twice as fast as creating (and |
454 | On the plus side, this function is about twice as fast as creating (and |
222 | destroying) a completely new coroutine, so if you need a lot of generic |
455 | destroying) a completely new coro, so if you need a lot of generic |
223 | coroutines in quick successsion, use C<async_pool>, not C<async>. |
456 | coros in quick successsion, use C<async_pool>, not C<async>. |
224 | |
457 | |
225 | The code block is executed in an C<eval> context and a warning will be |
458 | The code block is executed in an C<eval> context and a warning will be |
226 | issued in case of an exception instead of terminating the program, as |
459 | issued in case of an exception instead of terminating the program, as |
227 | C<async> does. As the coroutine is being reused, stuff like C<on_destroy> |
460 | C<async> does. As the coro is being reused, stuff like C<on_destroy> |
228 | will not work in the expected way, unless you call terminate or cancel, |
461 | will not work in the expected way, unless you call terminate or cancel, |
229 | which somehow defeats the purpose of pooling (but is fine in the |
462 | which somehow defeats the purpose of pooling (but is fine in the |
230 | exceptional case). |
463 | exceptional case). |
231 | |
464 | |
232 | The priority will be reset to C<0> after each run, tracing will be |
465 | The priority will be reset to C<0> after each run, tracing will be |
233 | disabled, the description will be reset and the default output filehandle |
466 | disabled, the description will be reset and the default output filehandle |
234 | gets restored, so you can change all these. Otherwise the coroutine will |
467 | gets restored, so you can change all these. Otherwise the coro will |
235 | be re-used "as-is": most notably if you change other per-coroutine global |
468 | be re-used "as-is": most notably if you change other per-coro global |
236 | stuff such as C<$/> you I<must needs> revert that change, which is most |
469 | stuff such as C<$/> you I<must needs> revert that change, which is most |
237 | simply done by using local as in: C<< local $/ >>. |
470 | simply done by using local as in: C<< local $/ >>. |
238 | |
471 | |
239 | The idle pool size is limited to C<8> idle coroutines (this can be |
472 | The idle pool size is limited to C<8> idle coros (this can be |
240 | adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle |
473 | adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle |
241 | coros as required. |
474 | coros as required. |
242 | |
475 | |
243 | If you are concerned about pooled coroutines growing a lot because a |
476 | If you are concerned about pooled coros growing a lot because a |
244 | single C<async_pool> used a lot of stackspace you can e.g. C<async_pool |
477 | single C<async_pool> used a lot of stackspace you can e.g. C<async_pool |
245 | { terminate }> once per second or so to slowly replenish the pool. In |
478 | { terminate }> once per second or so to slowly replenish the pool. In |
246 | addition to that, when the stacks used by a handler grows larger than 32kb |
479 | addition to that, when the stacks used by a handler grows larger than 32kb |
247 | (adjustable via $Coro::POOL_RSS) it will also be destroyed. |
480 | (adjustable via $Coro::POOL_RSS) it will also be destroyed. |
248 | |
481 | |
… | |
… | |
265 | =back |
498 | =back |
266 | |
499 | |
267 | =head1 STATIC METHODS |
500 | =head1 STATIC METHODS |
268 | |
501 | |
269 | Static methods are actually functions that implicitly operate on the |
502 | Static methods are actually functions that implicitly operate on the |
270 | current coroutine. |
503 | current coro. |
271 | |
504 | |
272 | =over 4 |
505 | =over 4 |
273 | |
506 | |
274 | =item schedule |
507 | =item schedule |
275 | |
508 | |
276 | Calls the scheduler. The scheduler will find the next coroutine that is |
509 | Calls the scheduler. The scheduler will find the next coro that is |
277 | to be run from the ready queue and switches to it. The next coroutine |
510 | to be run from the ready queue and switches to it. The next coro |
278 | to be run is simply the one with the highest priority that is longest |
511 | to be run is simply the one with the highest priority that is longest |
279 | in its ready queue. If there is no coroutine ready, it will clal the |
512 | in its ready queue. If there is no coro ready, it will call the |
280 | C<$Coro::idle> hook. |
513 | C<$Coro::idle> hook. |
281 | |
514 | |
282 | Please note that the current coroutine will I<not> be put into the ready |
515 | Please note that the current coro will I<not> be put into the ready |
283 | queue, so calling this function usually means you will never be called |
516 | queue, so calling this function usually means you will never be called |
284 | again unless something else (e.g. an event handler) calls C<< ->ready >>, |
517 | again unless something else (e.g. an event handler) calls C<< ->ready >>, |
285 | thus waking you up. |
518 | thus waking you up. |
286 | |
519 | |
287 | This makes C<schedule> I<the> generic method to use to block the current |
520 | This makes C<schedule> I<the> generic method to use to block the current |
288 | coroutine and wait for events: first you remember the current coroutine in |
521 | coro and wait for events: first you remember the current coro in |
289 | a variable, then arrange for some callback of yours to call C<< ->ready |
522 | a variable, then arrange for some callback of yours to call C<< ->ready |
290 | >> on that once some event happens, and last you call C<schedule> to put |
523 | >> on that once some event happens, and last you call C<schedule> to put |
291 | yourself to sleep. Note that a lot of things can wake your coroutine up, |
524 | yourself to sleep. Note that a lot of things can wake your coro up, |
292 | so you need to check whether the event indeed happened, e.g. by storing the |
525 | so you need to check whether the event indeed happened, e.g. by storing the |
293 | status in a variable. |
526 | status in a variable. |
294 | |
527 | |
295 | See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks. |
528 | See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks. |
296 | |
529 | |
297 | =item cede |
530 | =item cede |
298 | |
531 | |
299 | "Cede" to other coroutines. This function puts the current coroutine into |
532 | "Cede" to other coros. This function puts the current coro into |
300 | the ready queue and calls C<schedule>, which has the effect of giving |
533 | the ready queue and calls C<schedule>, which has the effect of giving |
301 | up the current "timeslice" to other coroutines of the same or higher |
534 | up the current "timeslice" to other coros of the same or higher |
302 | priority. Once your coroutine gets its turn again it will automatically be |
535 | priority. Once your coro gets its turn again it will automatically be |
303 | resumed. |
536 | resumed. |
304 | |
537 | |
305 | This function is often called C<yield> in other languages. |
538 | This function is often called C<yield> in other languages. |
306 | |
539 | |
307 | =item Coro::cede_notself |
540 | =item Coro::cede_notself |
308 | |
541 | |
309 | Works like cede, but is not exported by default and will cede to I<any> |
542 | Works like cede, but is not exported by default and will cede to I<any> |
310 | coroutine, regardless of priority. This is useful sometimes to ensure |
543 | coro, regardless of priority. This is useful sometimes to ensure |
311 | progress is made. |
544 | progress is made. |
312 | |
545 | |
313 | =item terminate [arg...] |
546 | =item terminate [arg...] |
314 | |
547 | |
315 | Terminates the current coroutine with the given status values (see L<cancel>). |
548 | Terminates the current coro with the given status values (see L<cancel>). |
|
|
549 | |
|
|
550 | =item Coro::on_enter BLOCK, Coro::on_leave BLOCK |
|
|
551 | |
|
|
552 | These function install enter and leave winders in the current scope. The |
|
|
553 | enter block will be executed when on_enter is called and whenever the |
|
|
554 | current coro is re-entered by the scheduler, while the leave block is |
|
|
555 | executed whenever the current coro is blocked by the scheduler, and |
|
|
556 | also when the containing scope is exited (by whatever means, be it exit, |
|
|
557 | die, last etc.). |
|
|
558 | |
|
|
559 | I<Neither invoking the scheduler, nor exceptions, are allowed within those |
|
|
560 | BLOCKs>. That means: do not even think about calling C<die> without an |
|
|
561 | eval, and do not even think of entering the scheduler in any way. |
|
|
562 | |
|
|
563 | Since both BLOCKs are tied to the current scope, they will automatically |
|
|
564 | be removed when the current scope exits. |
|
|
565 | |
|
|
566 | These functions implement the same concept as C<dynamic-wind> in scheme |
|
|
567 | does, and are useful when you want to localise some resource to a specific |
|
|
568 | coro. |
|
|
569 | |
|
|
570 | They slow down thread switching considerably for coros that use them |
|
|
571 | (about 40% for a BLOCK with a single assignment, so thread switching is |
|
|
572 | still reasonably fast if the handlers are fast). |
|
|
573 | |
|
|
574 | These functions are best understood by an example: The following function |
|
|
575 | will change the current timezone to "Antarctica/South_Pole", which |
|
|
576 | requires a call to C<tzset>, but by using C<on_enter> and C<on_leave>, |
|
|
577 | which remember/change the current timezone and restore the previous |
|
|
578 | value, respectively, the timezone is only changed for the coro that |
|
|
579 | installed those handlers. |
|
|
580 | |
|
|
581 | use POSIX qw(tzset); |
|
|
582 | |
|
|
583 | async { |
|
|
584 | my $old_tz; # store outside TZ value here |
|
|
585 | |
|
|
586 | Coro::on_enter { |
|
|
587 | $old_tz = $ENV{TZ}; # remember the old value |
|
|
588 | |
|
|
589 | $ENV{TZ} = "Antarctica/South_Pole"; |
|
|
590 | tzset; # enable new value |
|
|
591 | }; |
|
|
592 | |
|
|
593 | Coro::on_leave { |
|
|
594 | $ENV{TZ} = $old_tz; |
|
|
595 | tzset; # restore old value |
|
|
596 | }; |
|
|
597 | |
|
|
598 | # at this place, the timezone is Antarctica/South_Pole, |
|
|
599 | # without disturbing the TZ of any other coro. |
|
|
600 | }; |
|
|
601 | |
|
|
602 | This can be used to localise about any resource (locale, uid, current |
|
|
603 | working directory etc.) to a block, despite the existance of other |
|
|
604 | coros. |
|
|
605 | |
|
|
606 | Another interesting example implements time-sliced multitasking using |
|
|
607 | interval timers (this could obviously be optimised, but does the job): |
|
|
608 | |
|
|
609 | # "timeslice" the given block |
|
|
610 | sub timeslice(&) { |
|
|
611 | use Time::HiRes (); |
|
|
612 | |
|
|
613 | Coro::on_enter { |
|
|
614 | # on entering the thread, we set an VTALRM handler to cede |
|
|
615 | $SIG{VTALRM} = sub { cede }; |
|
|
616 | # and then start the interval timer |
|
|
617 | Time::HiRes::setitimer &Time::HiRes::ITIMER_VIRTUAL, 0.01, 0.01; |
|
|
618 | }; |
|
|
619 | Coro::on_leave { |
|
|
620 | # on leaving the thread, we stop the interval timer again |
|
|
621 | Time::HiRes::setitimer &Time::HiRes::ITIMER_VIRTUAL, 0, 0; |
|
|
622 | }; |
|
|
623 | |
|
|
624 | &{+shift}; |
|
|
625 | } |
|
|
626 | |
|
|
627 | # use like this: |
|
|
628 | timeslice { |
|
|
629 | # The following is an endless loop that would normally |
|
|
630 | # monopolise the process. Since it runs in a timesliced |
|
|
631 | # environment, it will regularly cede to other threads. |
|
|
632 | while () { } |
|
|
633 | }; |
|
|
634 | |
316 | |
635 | |
317 | =item killall |
636 | =item killall |
318 | |
637 | |
319 | Kills/terminates/cancels all coroutines except the currently running |
638 | Kills/terminates/cancels all coros except the currently running one. |
320 | one. This can be useful after a fork, either in the child or the parent, |
|
|
321 | as usually only one of them should inherit the running coroutines. |
|
|
322 | |
639 | |
323 | Note that in the implementation, destructors run as normal, making this |
|
|
324 | function not so useful after a fork. Future versions of this function |
|
|
325 | might try to free resources without running any code. |
|
|
326 | |
|
|
327 | Note that while this will try to free some of the main programs resources, |
640 | Note that while this will try to free some of the main interpreter |
|
|
641 | resources if the calling coro isn't the main coro, but one |
328 | you cannot free all of them, so if a coroutine that is not the main |
642 | cannot free all of them, so if a coro that is not the main coro |
329 | program calls this function, there will be some one-time resource leak. |
643 | calls this function, there will be some one-time resource leak. |
330 | |
644 | |
331 | =cut |
645 | =cut |
332 | |
646 | |
333 | sub killall { |
647 | sub killall { |
334 | for (Coro::State::list) { |
648 | for (Coro::State::list) { |
… | |
… | |
337 | } |
651 | } |
338 | } |
652 | } |
339 | |
653 | |
340 | =back |
654 | =back |
341 | |
655 | |
342 | =head1 COROUTINE OBJECT METHODS |
656 | =head1 CORO OBJECT METHODS |
343 | |
657 | |
344 | These are the methods you can call on coroutine objects (or to create |
658 | These are the methods you can call on coro objects (or to create |
345 | them). |
659 | them). |
346 | |
660 | |
347 | =over 4 |
661 | =over 4 |
348 | |
662 | |
349 | =item new Coro \&sub [, @args...] |
663 | =item new Coro \&sub [, @args...] |
350 | |
664 | |
351 | Create a new coroutine and return it. When the sub returns, the coroutine |
665 | Create a new coro and return it. When the sub returns, the coro |
352 | automatically terminates as if C<terminate> with the returned values were |
666 | automatically terminates as if C<terminate> with the returned values were |
353 | called. To make the coroutine run you must first put it into the ready |
667 | called. To make the coro run you must first put it into the ready |
354 | queue by calling the ready method. |
668 | queue by calling the ready method. |
355 | |
669 | |
356 | See C<async> and C<Coro::State::new> for additional info about the |
670 | See C<async> and C<Coro::State::new> for additional info about the |
357 | coroutine environment. |
671 | coro environment. |
358 | |
672 | |
359 | =cut |
673 | =cut |
360 | |
674 | |
361 | sub _coro_run { |
675 | sub _coro_run { |
362 | terminate &{+shift}; |
676 | terminate &{+shift}; |
363 | } |
677 | } |
364 | |
678 | |
365 | =item $success = $coroutine->ready |
679 | =item $success = $coro->ready |
366 | |
680 | |
367 | Put the given coroutine into the end of its ready queue (there is one |
681 | Put the given coro into the end of its ready queue (there is one |
368 | queue for each priority) and return true. If the coroutine is already in |
682 | queue for each priority) and return true. If the coro is already in |
369 | the ready queue, do nothing and return false. |
683 | the ready queue, do nothing and return false. |
370 | |
684 | |
371 | This ensures that the scheduler will resume this coroutine automatically |
685 | This ensures that the scheduler will resume this coro automatically |
372 | once all the coroutines of higher priority and all coroutines of the same |
686 | once all the coro of higher priority and all coro of the same |
373 | priority that were put into the ready queue earlier have been resumed. |
687 | priority that were put into the ready queue earlier have been resumed. |
374 | |
688 | |
|
|
689 | =item $coro->suspend |
|
|
690 | |
|
|
691 | Suspends the specified coro. A suspended coro works just like any other |
|
|
692 | coro, except that the scheduler will not select a suspended coro for |
|
|
693 | execution. |
|
|
694 | |
|
|
695 | Suspending a coro can be useful when you want to keep the coro from |
|
|
696 | running, but you don't want to destroy it, or when you want to temporarily |
|
|
697 | freeze a coro (e.g. for debugging) to resume it later. |
|
|
698 | |
|
|
699 | A scenario for the former would be to suspend all (other) coros after a |
|
|
700 | fork and keep them alive, so their destructors aren't called, but new |
|
|
701 | coros can be created. |
|
|
702 | |
|
|
703 | =item $coro->resume |
|
|
704 | |
|
|
705 | If the specified coro was suspended, it will be resumed. Note that when |
|
|
706 | the coro was in the ready queue when it was suspended, it might have been |
|
|
707 | unreadied by the scheduler, so an activation might have been lost. |
|
|
708 | |
|
|
709 | To avoid this, it is best to put a suspended coro into the ready queue |
|
|
710 | unconditionally, as every synchronisation mechanism must protect itself |
|
|
711 | against spurious wakeups, and the one in the Coro family certainly do |
|
|
712 | that. |
|
|
713 | |
375 | =item $is_ready = $coroutine->is_ready |
714 | =item $is_ready = $coro->is_ready |
376 | |
715 | |
377 | Return whether the coroutine is currently the ready queue or not, |
716 | Returns true iff the Coro object is in the ready queue. Unless the Coro |
|
|
717 | object gets destroyed, it will eventually be scheduled by the scheduler. |
378 | |
718 | |
|
|
719 | =item $is_running = $coro->is_running |
|
|
720 | |
|
|
721 | Returns true iff the Coro object is currently running. Only one Coro object |
|
|
722 | can ever be in the running state (but it currently is possible to have |
|
|
723 | multiple running Coro::States). |
|
|
724 | |
|
|
725 | =item $is_suspended = $coro->is_suspended |
|
|
726 | |
|
|
727 | Returns true iff this Coro object has been suspended. Suspended Coros will |
|
|
728 | not ever be scheduled. |
|
|
729 | |
379 | =item $coroutine->cancel (arg...) |
730 | =item $coro->cancel (arg...) |
380 | |
731 | |
381 | Terminates the given coroutine and makes it return the given arguments as |
732 | Terminates the given Coro and makes it return the given arguments as |
382 | status (default: the empty list). Never returns if the coroutine is the |
733 | status (default: the empty list). Never returns if the Coro is the |
383 | current coroutine. |
734 | current Coro. |
384 | |
735 | |
385 | =cut |
736 | =cut |
386 | |
737 | |
387 | sub cancel { |
738 | sub cancel { |
388 | my $self = shift; |
739 | my $self = shift; |
389 | |
740 | |
390 | if ($current == $self) { |
741 | if ($current == $self) { |
391 | terminate @_; |
742 | terminate @_; |
392 | } else { |
743 | } else { |
393 | $self->{_status} = [@_]; |
744 | $self->{_status} = [@_]; |
394 | $self->_cancel; |
745 | Coro::State::cancel $self; |
395 | } |
746 | } |
396 | } |
747 | } |
397 | |
748 | |
398 | =item $coroutine->schedule_to |
749 | =item $coro->schedule_to |
399 | |
750 | |
400 | Puts the current coroutine to sleep (like C<Coro::schedule>), but instead |
751 | Puts the current coro to sleep (like C<Coro::schedule>), but instead |
401 | of continuing with the next coro from the ready queue, always switch to |
752 | of continuing with the next coro from the ready queue, always switch to |
402 | the given coroutine object (regardless of priority etc.). The readyness |
753 | the given coro object (regardless of priority etc.). The readyness |
403 | state of that coroutine isn't changed. |
754 | state of that coro isn't changed. |
404 | |
755 | |
405 | This is an advanced method for special cases - I'd love to hear about any |
756 | This is an advanced method for special cases - I'd love to hear about any |
406 | uses for this one. |
757 | uses for this one. |
407 | |
758 | |
408 | =item $coroutine->cede_to |
759 | =item $coro->cede_to |
409 | |
760 | |
410 | Like C<schedule_to>, but puts the current coroutine into the ready |
761 | Like C<schedule_to>, but puts the current coro into the ready |
411 | queue. This has the effect of temporarily switching to the given |
762 | queue. This has the effect of temporarily switching to the given |
412 | coroutine, and continuing some time later. |
763 | coro, and continuing some time later. |
413 | |
764 | |
414 | This is an advanced method for special cases - I'd love to hear about any |
765 | This is an advanced method for special cases - I'd love to hear about any |
415 | uses for this one. |
766 | uses for this one. |
416 | |
767 | |
417 | =item $coroutine->throw ([$scalar]) |
768 | =item $coro->throw ([$scalar]) |
418 | |
769 | |
419 | If C<$throw> is specified and defined, it will be thrown as an exception |
770 | If C<$throw> is specified and defined, it will be thrown as an exception |
420 | inside the coroutine at the next convenient point in time. Otherwise |
771 | inside the coro at the next convenient point in time. Otherwise |
421 | clears the exception object. |
772 | clears the exception object. |
422 | |
773 | |
423 | Coro will check for the exception each time a schedule-like-function |
774 | Coro will check for the exception each time a schedule-like-function |
424 | returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down |
775 | returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down |
425 | >>, C<< Coro::Handle->readable >> and so on. Most of these functions |
776 | >>, C<< Coro::Handle->readable >> and so on. Most of these functions |
… | |
… | |
427 | |
778 | |
428 | The exception object will be thrown "as is" with the specified scalar in |
779 | The exception object will be thrown "as is" with the specified scalar in |
429 | C<$@>, i.e. if it is a string, no line number or newline will be appended |
780 | C<$@>, i.e. if it is a string, no line number or newline will be appended |
430 | (unlike with C<die>). |
781 | (unlike with C<die>). |
431 | |
782 | |
432 | This can be used as a softer means than C<cancel> to ask a coroutine to |
783 | This can be used as a softer means than C<cancel> to ask a coro to |
433 | end itself, although there is no guarantee that the exception will lead to |
784 | end itself, although there is no guarantee that the exception will lead to |
434 | termination, and if the exception isn't caught it might well end the whole |
785 | termination, and if the exception isn't caught it might well end the whole |
435 | program. |
786 | program. |
436 | |
787 | |
437 | You might also think of C<throw> as being the moral equivalent of |
788 | You might also think of C<throw> as being the moral equivalent of |
438 | C<kill>ing a coroutine with a signal (in this case, a scalar). |
789 | C<kill>ing a coro with a signal (in this case, a scalar). |
439 | |
790 | |
440 | =item $coroutine->join |
791 | =item $coro->join |
441 | |
792 | |
442 | Wait until the coroutine terminates and return any values given to the |
793 | Wait until the coro terminates and return any values given to the |
443 | C<terminate> or C<cancel> functions. C<join> can be called concurrently |
794 | C<terminate> or C<cancel> functions. C<join> can be called concurrently |
444 | from multiple coroutines, and all will be resumed and given the status |
795 | from multiple coro, and all will be resumed and given the status |
445 | return once the C<$coroutine> terminates. |
796 | return once the C<$coro> terminates. |
446 | |
797 | |
447 | =cut |
798 | =cut |
448 | |
799 | |
449 | sub join { |
800 | sub join { |
450 | my $self = shift; |
801 | my $self = shift; |
… | |
… | |
461 | } |
812 | } |
462 | |
813 | |
463 | wantarray ? @{$self->{_status}} : $self->{_status}[0]; |
814 | wantarray ? @{$self->{_status}} : $self->{_status}[0]; |
464 | } |
815 | } |
465 | |
816 | |
466 | =item $coroutine->on_destroy (\&cb) |
817 | =item $coro->on_destroy (\&cb) |
467 | |
818 | |
468 | Registers a callback that is called when this coroutine gets destroyed, |
819 | Registers a callback that is called when this coro thread gets destroyed, |
469 | but before it is joined. The callback gets passed the terminate arguments, |
820 | but before it is joined. The callback gets passed the terminate arguments, |
470 | if any, and I<must not> die, under any circumstances. |
821 | if any, and I<must not> die, under any circumstances. |
471 | |
822 | |
|
|
823 | There can be any number of C<on_destroy> callbacks per coro. |
|
|
824 | |
472 | =cut |
825 | =cut |
473 | |
826 | |
474 | sub on_destroy { |
827 | sub on_destroy { |
475 | my ($self, $cb) = @_; |
828 | my ($self, $cb) = @_; |
476 | |
829 | |
477 | push @{ $self->{_on_destroy} }, $cb; |
830 | push @{ $self->{_on_destroy} }, $cb; |
478 | } |
831 | } |
479 | |
832 | |
480 | =item $oldprio = $coroutine->prio ($newprio) |
833 | =item $oldprio = $coro->prio ($newprio) |
481 | |
834 | |
482 | Sets (or gets, if the argument is missing) the priority of the |
835 | Sets (or gets, if the argument is missing) the priority of the |
483 | coroutine. Higher priority coroutines get run before lower priority |
836 | coro thread. Higher priority coro get run before lower priority |
484 | coroutines. Priorities are small signed integers (currently -4 .. +3), |
837 | coros. Priorities are small signed integers (currently -4 .. +3), |
485 | that you can refer to using PRIO_xxx constants (use the import tag :prio |
838 | that you can refer to using PRIO_xxx constants (use the import tag :prio |
486 | to get then): |
839 | to get then): |
487 | |
840 | |
488 | PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN |
841 | PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN |
489 | 3 > 1 > 0 > -1 > -3 > -4 |
842 | 3 > 1 > 0 > -1 > -3 > -4 |
490 | |
843 | |
491 | # set priority to HIGH |
844 | # set priority to HIGH |
492 | current->prio(PRIO_HIGH); |
845 | current->prio (PRIO_HIGH); |
493 | |
846 | |
494 | The idle coroutine ($Coro::idle) always has a lower priority than any |
847 | The idle coro thread ($Coro::idle) always has a lower priority than any |
495 | existing coroutine. |
848 | existing coro. |
496 | |
849 | |
497 | Changing the priority of the current coroutine will take effect immediately, |
850 | Changing the priority of the current coro will take effect immediately, |
498 | but changing the priority of coroutines in the ready queue (but not |
851 | but changing the priority of a coro in the ready queue (but not running) |
499 | running) will only take effect after the next schedule (of that |
852 | will only take effect after the next schedule (of that coro). This is a |
500 | coroutine). This is a bug that will be fixed in some future version. |
853 | bug that will be fixed in some future version. |
501 | |
854 | |
502 | =item $newprio = $coroutine->nice ($change) |
855 | =item $newprio = $coro->nice ($change) |
503 | |
856 | |
504 | Similar to C<prio>, but subtract the given value from the priority (i.e. |
857 | Similar to C<prio>, but subtract the given value from the priority (i.e. |
505 | higher values mean lower priority, just as in unix). |
858 | higher values mean lower priority, just as in UNIX's nice command). |
506 | |
859 | |
507 | =item $olddesc = $coroutine->desc ($newdesc) |
860 | =item $olddesc = $coro->desc ($newdesc) |
508 | |
861 | |
509 | Sets (or gets in case the argument is missing) the description for this |
862 | Sets (or gets in case the argument is missing) the description for this |
510 | coroutine. This is just a free-form string you can associate with a |
863 | coro thread. This is just a free-form string you can associate with a |
511 | coroutine. |
864 | coro. |
512 | |
865 | |
513 | This method simply sets the C<< $coroutine->{desc} >> member to the given |
866 | This method simply sets the C<< $coro->{desc} >> member to the given |
514 | string. You can modify this member directly if you wish. |
867 | string. You can modify this member directly if you wish, and in fact, this |
|
|
868 | is often preferred to indicate major processing states that cna then be |
|
|
869 | seen for example in a L<Coro::Debug> session: |
|
|
870 | |
|
|
871 | sub my_long_function { |
|
|
872 | local $Coro::current->{desc} = "now in my_long_function"; |
|
|
873 | ... |
|
|
874 | $Coro::current->{desc} = "my_long_function: phase 1"; |
|
|
875 | ... |
|
|
876 | $Coro::current->{desc} = "my_long_function: phase 2"; |
|
|
877 | ... |
|
|
878 | } |
515 | |
879 | |
516 | =cut |
880 | =cut |
517 | |
881 | |
518 | sub desc { |
882 | sub desc { |
519 | my $old = $_[0]{desc}; |
883 | my $old = $_[0]{desc}; |
… | |
… | |
532 | |
896 | |
533 | =over 4 |
897 | =over 4 |
534 | |
898 | |
535 | =item Coro::nready |
899 | =item Coro::nready |
536 | |
900 | |
537 | Returns the number of coroutines that are currently in the ready state, |
901 | Returns the number of coro that are currently in the ready state, |
538 | i.e. that can be switched to by calling C<schedule> directory or |
902 | i.e. that can be switched to by calling C<schedule> directory or |
539 | indirectly. The value C<0> means that the only runnable coroutine is the |
903 | indirectly. The value C<0> means that the only runnable coro is the |
540 | currently running one, so C<cede> would have no effect, and C<schedule> |
904 | currently running one, so C<cede> would have no effect, and C<schedule> |
541 | would cause a deadlock unless there is an idle handler that wakes up some |
905 | would cause a deadlock unless there is an idle handler that wakes up some |
542 | coroutines. |
906 | coro. |
543 | |
907 | |
544 | =item my $guard = Coro::guard { ... } |
908 | =item my $guard = Coro::guard { ... } |
545 | |
909 | |
546 | This function still exists, but is deprecated. Please use the |
910 | This function still exists, but is deprecated. Please use the |
547 | C<Guard::guard> function instead. |
911 | C<Guard::guard> function instead. |
… | |
… | |
554 | |
918 | |
555 | This utility function takes a BLOCK or code reference and "unblocks" it, |
919 | This utility function takes a BLOCK or code reference and "unblocks" it, |
556 | returning a new coderef. Unblocking means that calling the new coderef |
920 | returning a new coderef. Unblocking means that calling the new coderef |
557 | will return immediately without blocking, returning nothing, while the |
921 | will return immediately without blocking, returning nothing, while the |
558 | original code ref will be called (with parameters) from within another |
922 | original code ref will be called (with parameters) from within another |
559 | coroutine. |
923 | coro. |
560 | |
924 | |
561 | The reason this function exists is that many event libraries (such as the |
925 | The reason this function exists is that many event libraries (such as |
562 | venerable L<Event|Event> module) are not coroutine-safe (a weaker form |
926 | the venerable L<Event|Event> module) are not thread-safe (a weaker form |
563 | of reentrancy). This means you must not block within event callbacks, |
927 | of reentrancy). This means you must not block within event callbacks, |
564 | otherwise you might suffer from crashes or worse. The only event library |
928 | otherwise you might suffer from crashes or worse. The only event library |
565 | currently known that is safe to use without C<unblock_sub> is L<EV>. |
929 | currently known that is safe to use without C<unblock_sub> is L<EV> (but |
|
|
930 | you might still run into deadlocks if all event loops are blocked). |
|
|
931 | |
|
|
932 | Coro will try to catch you when you block in the event loop |
|
|
933 | ("FATAL:$Coro::IDLE blocked itself"), but this is just best effort and |
|
|
934 | only works when you do not run your own event loop. |
566 | |
935 | |
567 | This function allows your callbacks to block by executing them in another |
936 | This function allows your callbacks to block by executing them in another |
568 | coroutine where it is safe to block. One example where blocking is handy |
937 | coro where it is safe to block. One example where blocking is handy |
569 | is when you use the L<Coro::AIO|Coro::AIO> functions to save results to |
938 | is when you use the L<Coro::AIO|Coro::AIO> functions to save results to |
570 | disk, for example. |
939 | disk, for example. |
571 | |
940 | |
572 | In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when |
941 | In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when |
573 | creating event callbacks that want to block. |
942 | creating event callbacks that want to block. |
574 | |
943 | |
575 | If your handler does not plan to block (e.g. simply sends a message to |
944 | If your handler does not plan to block (e.g. simply sends a message to |
576 | another coroutine, or puts some other coroutine into the ready queue), |
945 | another coro, or puts some other coro into the ready queue), there is |
577 | there is no reason to use C<unblock_sub>. |
946 | no reason to use C<unblock_sub>. |
578 | |
947 | |
579 | Note that you also need to use C<unblock_sub> for any other callbacks that |
948 | Note that you also need to use C<unblock_sub> for any other callbacks that |
580 | are indirectly executed by any C-based event loop. For example, when you |
949 | are indirectly executed by any C-based event loop. For example, when you |
581 | use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it |
950 | use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it |
582 | provides callbacks that are the result of some event callback, then you |
951 | provides callbacks that are the result of some event callback, then you |
… | |
… | |
612 | unshift @unblock_queue, [$cb, @_]; |
981 | unshift @unblock_queue, [$cb, @_]; |
613 | $unblock_scheduler->ready; |
982 | $unblock_scheduler->ready; |
614 | } |
983 | } |
615 | } |
984 | } |
616 | |
985 | |
617 | =item $cb = Coro::rouse_cb |
986 | =item $cb = rouse_cb |
618 | |
987 | |
619 | Create and return a "rouse callback". That's a code reference that, |
988 | Create and return a "rouse callback". That's a code reference that, |
620 | when called, will remember a copy of its arguments and notify the owner |
989 | when called, will remember a copy of its arguments and notify the owner |
621 | coroutine of the callback. |
990 | coro of the callback. |
622 | |
991 | |
623 | See the next function. |
992 | See the next function. |
624 | |
993 | |
625 | =item @args = Coro::rouse_wait [$cb] |
994 | =item @args = rouse_wait [$cb] |
626 | |
995 | |
627 | Wait for the specified rouse callback (or the last one that was created in |
996 | Wait for the specified rouse callback (or the last one that was created in |
628 | this coroutine). |
997 | this coro). |
629 | |
998 | |
630 | As soon as the callback is invoked (or when the callback was invoked |
999 | As soon as the callback is invoked (or when the callback was invoked |
631 | before C<rouse_wait>), it will return the arguments originally passed to |
1000 | before C<rouse_wait>), it will return the arguments originally passed to |
632 | the rouse callback. |
1001 | the rouse callback. In scalar context, that means you get the I<last> |
|
|
1002 | argument, just as if C<rouse_wait> had a C<return ($a1, $a2, $a3...)> |
|
|
1003 | statement at the end. |
633 | |
1004 | |
634 | See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example. |
1005 | See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example. |
635 | |
1006 | |
636 | =back |
1007 | =back |
637 | |
1008 | |
638 | =cut |
1009 | =cut |
639 | |
1010 | |
|
|
1011 | for my $module (qw(Channel RWLock Semaphore SemaphoreSet Signal Specific)) { |
|
|
1012 | my $old = defined &{"Coro::$module\::new"} && \&{"Coro::$module\::new"}; |
|
|
1013 | |
|
|
1014 | *{"Coro::$module\::new"} = sub { |
|
|
1015 | require "Coro/$module.pm"; |
|
|
1016 | |
|
|
1017 | # some modules have their new predefined in State.xs, some don't |
|
|
1018 | *{"Coro::$module\::new"} = $old |
|
|
1019 | if $old; |
|
|
1020 | |
|
|
1021 | goto &{"Coro::$module\::new"}; |
|
|
1022 | }; |
|
|
1023 | } |
|
|
1024 | |
640 | 1; |
1025 | 1; |
641 | |
1026 | |
642 | =head1 HOW TO WAIT FOR A CALLBACK |
1027 | =head1 HOW TO WAIT FOR A CALLBACK |
643 | |
1028 | |
644 | It is very common for a coroutine to wait for some callback to be |
1029 | It is very common for a coro to wait for some callback to be |
645 | called. This occurs naturally when you use coroutines in an otherwise |
1030 | called. This occurs naturally when you use coro in an otherwise |
646 | event-based program, or when you use event-based libraries. |
1031 | event-based program, or when you use event-based libraries. |
647 | |
1032 | |
648 | These typically register a callback for some event, and call that callback |
1033 | These typically register a callback for some event, and call that callback |
649 | when the event occured. In a coroutine, however, you typically want to |
1034 | when the event occured. In a coro, however, you typically want to |
650 | just wait for the event, simplyifying things. |
1035 | just wait for the event, simplyifying things. |
651 | |
1036 | |
652 | For example C<< AnyEvent->child >> registers a callback to be called when |
1037 | For example C<< AnyEvent->child >> registers a callback to be called when |
653 | a specific child has exited: |
1038 | a specific child has exited: |
654 | |
1039 | |
655 | my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... }); |
1040 | my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... }); |
656 | |
1041 | |
657 | But from withina coroutine, you often just want to write this: |
1042 | But from within a coro, you often just want to write this: |
658 | |
1043 | |
659 | my $status = wait_for_child $pid; |
1044 | my $status = wait_for_child $pid; |
660 | |
1045 | |
661 | Coro offers two functions specifically designed to make this easy, |
1046 | Coro offers two functions specifically designed to make this easy, |
662 | C<Coro::rouse_cb> and C<Coro::rouse_wait>. |
1047 | C<Coro::rouse_cb> and C<Coro::rouse_wait>. |
663 | |
1048 | |
664 | The first function, C<rouse_cb>, generates and returns a callback that, |
1049 | The first function, C<rouse_cb>, generates and returns a callback that, |
665 | when invoked, will save its arguments and notify the coroutine that |
1050 | when invoked, will save its arguments and notify the coro that |
666 | created the callback. |
1051 | created the callback. |
667 | |
1052 | |
668 | The second function, C<rouse_wait>, waits for the callback to be called |
1053 | The second function, C<rouse_wait>, waits for the callback to be called |
669 | (by calling C<schedule> to go to sleep) and returns the arguments |
1054 | (by calling C<schedule> to go to sleep) and returns the arguments |
670 | originally passed to the callback. |
1055 | originally passed to the callback. |
… | |
… | |
685 | you can roll your own, using C<schedule>: |
1070 | you can roll your own, using C<schedule>: |
686 | |
1071 | |
687 | sub wait_for_child($) { |
1072 | sub wait_for_child($) { |
688 | my ($pid) = @_; |
1073 | my ($pid) = @_; |
689 | |
1074 | |
690 | # store the current coroutine in $current, |
1075 | # store the current coro in $current, |
691 | # and provide result variables for the closure passed to ->child |
1076 | # and provide result variables for the closure passed to ->child |
692 | my $current = $Coro::current; |
1077 | my $current = $Coro::current; |
693 | my ($done, $rstatus); |
1078 | my ($done, $rstatus); |
694 | |
1079 | |
695 | # pass a closure to ->child |
1080 | # pass a closure to ->child |
… | |
… | |
711 | |
1096 | |
712 | =item fork with pthread backend |
1097 | =item fork with pthread backend |
713 | |
1098 | |
714 | When Coro is compiled using the pthread backend (which isn't recommended |
1099 | When Coro is compiled using the pthread backend (which isn't recommended |
715 | but required on many BSDs as their libcs are completely broken), then |
1100 | but required on many BSDs as their libcs are completely broken), then |
716 | coroutines will not survive a fork. There is no known workaround except to |
1101 | coro will not survive a fork. There is no known workaround except to |
717 | fix your libc and use a saner backend. |
1102 | fix your libc and use a saner backend. |
718 | |
1103 | |
719 | =item perl process emulation ("threads") |
1104 | =item perl process emulation ("threads") |
720 | |
1105 | |
721 | This module is not perl-pseudo-thread-safe. You should only ever use this |
1106 | This module is not perl-pseudo-thread-safe. You should only ever use this |
… | |
… | |
723 | future to allow per-thread schedulers, but Coro::State does not yet allow |
1108 | future to allow per-thread schedulers, but Coro::State does not yet allow |
724 | this). I recommend disabling thread support and using processes, as having |
1109 | this). I recommend disabling thread support and using processes, as having |
725 | the windows process emulation enabled under unix roughly halves perl |
1110 | the windows process emulation enabled under unix roughly halves perl |
726 | performance, even when not used. |
1111 | performance, even when not used. |
727 | |
1112 | |
728 | =item coroutine switching not signal safe |
1113 | =item coro switching is not signal safe |
729 | |
1114 | |
730 | You must not switch to another coroutine from within a signal handler |
1115 | You must not switch to another coro from within a signal handler (only |
731 | (only relevant with %SIG - most event libraries provide safe signals). |
1116 | relevant with %SIG - most event libraries provide safe signals), I<unless> |
|
|
1117 | you are sure you are not interrupting a Coro function. |
732 | |
1118 | |
733 | That means you I<MUST NOT> call any function that might "block" the |
1119 | That means you I<MUST NOT> call any function that might "block" the |
734 | current coroutine - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or |
1120 | current coro - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or |
735 | anything that calls those. Everything else, including calling C<ready>, |
1121 | anything that calls those. Everything else, including calling C<ready>, |
736 | works. |
1122 | works. |
737 | |
1123 | |
738 | =back |
1124 | =back |
739 | |
1125 | |
|
|
1126 | |
|
|
1127 | =head1 WINDOWS PROCESS EMULATION |
|
|
1128 | |
|
|
1129 | A great many people seem to be confused about ithreads (for example, Chip |
|
|
1130 | Salzenberg called me unintelligent, incapable, stupid and gullible, |
|
|
1131 | while in the same mail making rather confused statements about perl |
|
|
1132 | ithreads (for example, that memory or files would be shared), showing his |
|
|
1133 | lack of understanding of this area - if it is hard to understand for Chip, |
|
|
1134 | it is probably not obvious to everybody). |
|
|
1135 | |
|
|
1136 | What follows is an ultra-condensed version of my talk about threads in |
|
|
1137 | scripting languages given on the perl workshop 2009: |
|
|
1138 | |
|
|
1139 | The so-called "ithreads" were originally implemented for two reasons: |
|
|
1140 | first, to (badly) emulate unix processes on native win32 perls, and |
|
|
1141 | secondly, to replace the older, real thread model ("5.005-threads"). |
|
|
1142 | |
|
|
1143 | It does that by using threads instead of OS processes. The difference |
|
|
1144 | between processes and threads is that threads share memory (and other |
|
|
1145 | state, such as files) between threads within a single process, while |
|
|
1146 | processes do not share anything (at least not semantically). That |
|
|
1147 | means that modifications done by one thread are seen by others, while |
|
|
1148 | modifications by one process are not seen by other processes. |
|
|
1149 | |
|
|
1150 | The "ithreads" work exactly like that: when creating a new ithreads |
|
|
1151 | process, all state is copied (memory is copied physically, files and code |
|
|
1152 | is copied logically). Afterwards, it isolates all modifications. On UNIX, |
|
|
1153 | the same behaviour can be achieved by using operating system processes, |
|
|
1154 | except that UNIX typically uses hardware built into the system to do this |
|
|
1155 | efficiently, while the windows process emulation emulates this hardware in |
|
|
1156 | software (rather efficiently, but of course it is still much slower than |
|
|
1157 | dedicated hardware). |
|
|
1158 | |
|
|
1159 | As mentioned before, loading code, modifying code, modifying data |
|
|
1160 | structures and so on is only visible in the ithreads process doing the |
|
|
1161 | modification, not in other ithread processes within the same OS process. |
|
|
1162 | |
|
|
1163 | This is why "ithreads" do not implement threads for perl at all, only |
|
|
1164 | processes. What makes it so bad is that on non-windows platforms, you can |
|
|
1165 | actually take advantage of custom hardware for this purpose (as evidenced |
|
|
1166 | by the forks module, which gives you the (i-) threads API, just much |
|
|
1167 | faster). |
|
|
1168 | |
|
|
1169 | Sharing data is in the i-threads model is done by transfering data |
|
|
1170 | structures between threads using copying semantics, which is very slow - |
|
|
1171 | shared data simply does not exist. Benchmarks using i-threads which are |
|
|
1172 | communication-intensive show extremely bad behaviour with i-threads (in |
|
|
1173 | fact, so bad that Coro, which cannot take direct advantage of multiple |
|
|
1174 | CPUs, is often orders of magnitude faster because it shares data using |
|
|
1175 | real threads, refer to my talk for details). |
|
|
1176 | |
|
|
1177 | As summary, i-threads *use* threads to implement processes, while |
|
|
1178 | the compatible forks module *uses* processes to emulate, uhm, |
|
|
1179 | processes. I-threads slow down every perl program when enabled, and |
|
|
1180 | outside of windows, serve no (or little) practical purpose, but |
|
|
1181 | disadvantages every single-threaded Perl program. |
|
|
1182 | |
|
|
1183 | This is the reason that I try to avoid the name "ithreads", as it is |
|
|
1184 | misleading as it implies that it implements some kind of thread model for |
|
|
1185 | perl, and prefer the name "windows process emulation", which describes the |
|
|
1186 | actual use and behaviour of it much better. |
740 | |
1187 | |
741 | =head1 SEE ALSO |
1188 | =head1 SEE ALSO |
742 | |
1189 | |
743 | Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>. |
1190 | Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>. |
744 | |
1191 | |