1 | =head1 NAME |
1 | =head1 NAME |
2 | |
2 | |
3 | Coro - coroutine process abstraction |
3 | Coro - the only real threads in perl |
4 | |
4 | |
5 | =head1 SYNOPSIS |
5 | =head1 SYNOPSIS |
6 | |
6 | |
7 | use Coro; |
7 | use Coro; |
8 | |
8 | |
9 | async { |
9 | async { |
10 | # some asynchronous thread of execution |
10 | # some asynchronous thread of execution |
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11 | print "2\n"; |
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12 | cede; # yield back to main |
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13 | print "4\n"; |
11 | }; |
14 | }; |
12 | |
15 | print "1\n"; |
13 | # alternatively create an async process like this: |
16 | cede; # yield to coroutine |
14 | |
17 | print "3\n"; |
15 | sub some_func : Coro { |
18 | cede; # and again |
16 | # some more async code |
19 | |
17 | } |
20 | # use locking |
18 | |
21 | use Coro::Semaphore; |
19 | yield; |
22 | my $lock = new Coro::Semaphore; |
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23 | my $locked; |
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24 | |
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25 | $lock->down; |
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26 | $locked = 1; |
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27 | $lock->up; |
20 | |
28 | |
21 | =head1 DESCRIPTION |
29 | =head1 DESCRIPTION |
22 | |
30 | |
23 | This module collection manages coroutines. Coroutines are similar to |
31 | For a tutorial-style introduction, please read the L<Coro::Intro> |
24 | Threads but don't run in parallel. |
32 | manpage. This manpage mainly contains reference information. |
25 | |
33 | |
26 | This module is still experimental, see the BUGS section below. |
34 | This module collection manages continuations in general, most often |
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35 | in the form of cooperative threads (also called coroutines in the |
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36 | documentation). They are similar to kernel threads but don't (in general) |
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37 | run in parallel at the same time even on SMP machines. The specific flavor |
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38 | of thread offered by this module also guarantees you that it will not |
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39 | switch between threads unless necessary, at easily-identified points in |
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40 | your program, so locking and parallel access are rarely an issue, making |
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41 | thread programming much safer and easier than using other thread models. |
27 | |
42 | |
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43 | Unlike the so-called "Perl threads" (which are not actually real threads |
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44 | but only the windows process emulation ported to unix), Coro provides a |
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45 | full shared address space, which makes communication between threads |
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46 | very easy. And threads are fast, too: disabling the Windows process |
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47 | emulation code in your perl and using Coro can easily result in a two to |
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48 | four times speed increase for your programs. |
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49 | |
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50 | Coro achieves that by supporting multiple running interpreters that share |
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51 | data, which is especially useful to code pseudo-parallel processes and |
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52 | for event-based programming, such as multiple HTTP-GET requests running |
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53 | concurrently. See L<Coro::AnyEvent> to learn more on how to integrate Coro |
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54 | into an event-based environment. |
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55 | |
28 | In this module, coroutines are defined as "callchain + lexical variables |
56 | In this module, a thread is defined as "callchain + lexical variables + |
29 | + @_ + $_ + $@ + $^W), that is, a coroutine has it's own callchain, it's |
57 | @_ + $_ + $@ + $/ + C stack), that is, a thread has its own callchain, |
30 | own set of lexicals and it's own set of perl's most important global |
58 | its own set of lexicals and its own set of perls most important global |
31 | variables. |
59 | variables (see L<Coro::State> for more configuration and background info). |
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60 | |
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61 | See also the C<SEE ALSO> section at the end of this document - the Coro |
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62 | module family is quite large. |
32 | |
63 | |
33 | =cut |
64 | =cut |
34 | |
65 | |
35 | package Coro; |
66 | package Coro; |
36 | |
67 | |
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68 | use strict qw(vars subs); |
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69 | no warnings "uninitialized"; |
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70 | |
37 | use Coro::State; |
71 | use Coro::State; |
38 | |
72 | |
39 | use base Exporter; |
73 | use base qw(Coro::State Exporter); |
40 | |
74 | |
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75 | our $idle; # idle handler |
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76 | our $main; # main coroutine |
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77 | our $current; # current coroutine |
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78 | |
41 | $VERSION = 0.10; |
79 | our $VERSION = 5.12; |
42 | |
80 | |
43 | @EXPORT = qw(async yield schedule terminate current); |
81 | our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); |
44 | @EXPORT_OK = qw($current); |
82 | our %EXPORT_TAGS = ( |
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83 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
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84 | ); |
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85 | our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready)); |
45 | |
86 | |
46 | { |
87 | =head1 GLOBAL VARIABLES |
47 | my @async; |
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48 | |
88 | |
49 | # this way of handling attributes simply is NOT scalable ;() |
89 | =over 4 |
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 | |
90 | |
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 |
91 | =item $Coro::main |
73 | |
92 | |
74 | This coroutine represents the main program. |
93 | This variable stores the coroutine object that represents the main |
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94 | program. While you cna C<ready> it and do most other things you can do to |
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95 | coroutines, it is mainly useful to compare again C<$Coro::current>, to see |
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96 | whether you are running in the main program or not. |
75 | |
97 | |
76 | =cut |
98 | =cut |
77 | |
99 | |
78 | our $main = new Coro; |
100 | # $main is now being initialised by Coro::State |
79 | |
101 | |
80 | =item $current (or as function: current) |
102 | =item $Coro::current |
81 | |
103 | |
82 | The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course). |
104 | The coroutine object representing the current coroutine (the last |
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105 | coroutine that the Coro scheduler switched to). The initial value is |
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106 | C<$Coro::main> (of course). |
83 | |
107 | |
84 | =cut |
108 | This variable is B<strictly> I<read-only>. You can take copies of the |
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109 | value stored in it and use it as any other coroutine object, but you must |
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110 | not otherwise modify the variable itself. |
85 | |
111 | |
86 | # maybe some other module used Coro::Specific before... |
112 | =cut |
87 | if ($current) { |
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88 | $main->{specific} = $current->{specific}; |
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89 | } |
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90 | |
113 | |
91 | our $current = $main; |
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92 | |
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93 | sub current() { $current } |
114 | sub current() { $current } # [DEPRECATED] |
94 | |
115 | |
95 | =item $idle |
116 | =item $Coro::idle |
96 | |
117 | |
97 | The coroutine to switch to when no other coroutine is running. The default |
118 | This variable is mainly useful to integrate Coro into event loops. It is |
98 | implementation prints "FATAL: deadlock detected" and exits. |
119 | usually better to rely on L<Coro::AnyEvent> or L<Coro::EV>, as this is |
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120 | pretty low-level functionality. |
99 | |
121 | |
100 | =cut |
122 | This variable stores either a coroutine or a callback. |
101 | |
123 | |
102 | # should be done using priorities :( |
124 | If it is a callback, the it is called whenever the scheduler finds no |
103 | our $idle = new Coro sub { |
125 | ready coroutines to run. The default implementation prints "FATAL: |
104 | print STDERR "FATAL: deadlock detected\n"; |
126 | deadlock detected" and exits, because the program has no other way to |
105 | exit(51); |
127 | continue. |
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128 | |
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129 | If it is a coroutine object, then this object will be readied (without |
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130 | invoking any ready hooks, however) when the scheduler finds no other ready |
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131 | coroutines to run. |
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132 | |
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133 | This hook is overwritten by modules such as C<Coro::EV> and |
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134 | C<Coro::AnyEvent> to wait on an external event that hopefully wake up a |
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135 | coroutine so the scheduler can run it. |
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136 | |
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137 | Note that the callback I<must not>, under any circumstances, block |
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138 | the current coroutine. Normally, this is achieved by having an "idle |
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139 | coroutine" that calls the event loop and then blocks again, and then |
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140 | readying that coroutine in the idle handler, or by simply placing the idle |
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141 | coroutine in this variable. |
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142 | |
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143 | See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this |
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144 | technique. |
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145 | |
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146 | Please note that if your callback recursively invokes perl (e.g. for event |
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147 | handlers), then it must be prepared to be called recursively itself. |
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148 | |
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149 | =cut |
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150 | |
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151 | $idle = sub { |
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152 | require Carp; |
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153 | Carp::croak ("FATAL: deadlock detected"); |
106 | }; |
154 | }; |
107 | |
155 | |
108 | # we really need priorities... |
156 | # this coroutine is necessary because a coroutine |
109 | my @ready; # the ready queue. hehe, rather broken ;) |
157 | # cannot destroy itself. |
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158 | our @destroy; |
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159 | our $manager; |
110 | |
160 | |
111 | # static methods. not really. |
161 | $manager = new Coro sub { |
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162 | while () { |
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163 | Coro::_cancel shift @destroy |
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164 | while @destroy; |
112 | |
165 | |
113 | =head2 STATIC METHODS |
166 | &schedule; |
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167 | } |
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168 | }; |
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169 | $manager->{desc} = "[coro manager]"; |
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170 | $manager->prio (PRIO_MAX); |
114 | |
171 | |
115 | Static methods are actually functions that operate on the current process only. |
172 | =back |
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173 | |
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174 | =head1 SIMPLE COROUTINE CREATION |
116 | |
175 | |
117 | =over 4 |
176 | =over 4 |
118 | |
177 | |
119 | =item async { ... } [@args...] |
178 | =item async { ... } [@args...] |
120 | |
179 | |
121 | Create a new asynchronous process and return it's process object |
180 | Create a new coroutine and return its coroutine object (usually |
122 | (usually unused). When the sub returns the new process is automatically |
181 | unused). The coroutine will be put into the ready queue, so |
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182 | it will start running automatically on the next scheduler run. |
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183 | |
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184 | The first argument is a codeblock/closure that should be executed in the |
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185 | coroutine. When it returns argument returns the coroutine is automatically |
123 | terminated. |
186 | terminated. |
124 | |
187 | |
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188 | The remaining arguments are passed as arguments to the closure. |
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189 | |
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190 | See the C<Coro::State::new> constructor for info about the coroutine |
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191 | environment in which coroutines are executed. |
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192 | |
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193 | Calling C<exit> in a coroutine will do the same as calling exit outside |
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194 | the coroutine. Likewise, when the coroutine dies, the program will exit, |
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195 | just as it would in the main program. |
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196 | |
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197 | If you do not want that, you can provide a default C<die> handler, or |
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198 | simply avoid dieing (by use of C<eval>). |
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199 | |
125 | # create a new coroutine that just prints its arguments |
200 | Example: Create a new coroutine that just prints its arguments. |
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201 | |
126 | async { |
202 | async { |
127 | print "@_\n"; |
203 | print "@_\n"; |
128 | } 1,2,3,4; |
204 | } 1,2,3,4; |
129 | |
205 | |
130 | The coderef you submit MUST NOT be a closure that refers to variables |
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131 | in an outer scope. This does NOT work. Pass arguments into it instead. |
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132 | |
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133 | =cut |
206 | =cut |
134 | |
207 | |
135 | sub async(&@) { |
208 | sub async(&@) { |
136 | my $pid = new Coro @_; |
209 | my $coro = new Coro @_; |
137 | $pid->ready; |
210 | $coro->ready; |
138 | $pid; |
211 | $coro |
139 | } |
212 | } |
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213 | |
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214 | =item async_pool { ... } [@args...] |
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215 | |
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216 | Similar to C<async>, but uses a coroutine pool, so you should not call |
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217 | terminate or join on it (although you are allowed to), and you get a |
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218 | coroutine that might have executed other code already (which can be good |
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219 | or bad :). |
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220 | |
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221 | On the plus side, this function is about twice as fast as creating (and |
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222 | destroying) a completely new coroutine, so if you need a lot of generic |
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223 | coroutines in quick successsion, use C<async_pool>, not C<async>. |
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224 | |
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225 | The code block is executed in an C<eval> context and a warning will be |
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226 | issued in case of an exception instead of terminating the program, as |
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227 | C<async> does. As the coroutine is being reused, stuff like C<on_destroy> |
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228 | will not work in the expected way, unless you call terminate or cancel, |
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229 | which somehow defeats the purpose of pooling (but is fine in the |
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230 | exceptional case). |
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231 | |
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232 | The priority will be reset to C<0> after each run, tracing will be |
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233 | disabled, the description will be reset and the default output filehandle |
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234 | gets restored, so you can change all these. Otherwise the coroutine will |
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235 | be re-used "as-is": most notably if you change other per-coroutine global |
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236 | stuff such as C<$/> you I<must needs> revert that change, which is most |
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237 | simply done by using local as in: C<< local $/ >>. |
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238 | |
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239 | The idle pool size is limited to C<8> idle coroutines (this can be |
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240 | adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle |
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241 | coros as required. |
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242 | |
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243 | If you are concerned about pooled coroutines growing a lot because a |
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244 | single C<async_pool> used a lot of stackspace you can e.g. C<async_pool |
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245 | { terminate }> once per second or so to slowly replenish the pool. In |
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246 | addition to that, when the stacks used by a handler grows larger than 32kb |
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247 | (adjustable via $Coro::POOL_RSS) it will also be destroyed. |
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248 | |
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249 | =cut |
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250 | |
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251 | our $POOL_SIZE = 8; |
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252 | our $POOL_RSS = 32 * 1024; |
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253 | our @async_pool; |
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254 | |
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255 | sub pool_handler { |
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256 | while () { |
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257 | eval { |
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258 | &{&_pool_handler} while 1; |
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259 | }; |
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260 | |
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261 | warn $@ if $@; |
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262 | } |
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263 | } |
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264 | |
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265 | =back |
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266 | |
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267 | =head1 STATIC METHODS |
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268 | |
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269 | Static methods are actually functions that implicitly operate on the |
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270 | current coroutine. |
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271 | |
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272 | =over 4 |
140 | |
273 | |
141 | =item schedule |
274 | =item schedule |
142 | |
275 | |
143 | Calls the scheduler. Please note that the current process will not be put |
276 | Calls the scheduler. The scheduler will find the next coroutine that is |
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277 | to be run from the ready queue and switches to it. The next coroutine |
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278 | to be run is simply the one with the highest priority that is longest |
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279 | in its ready queue. If there is no coroutine ready, it will clal the |
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280 | C<$Coro::idle> hook. |
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281 | |
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282 | Please note that the current coroutine will I<not> be put into the ready |
144 | into the ready queue, so calling this function usually means you will |
283 | queue, so calling this function usually means you will never be called |
145 | never be called again. |
284 | again unless something else (e.g. an event handler) calls C<< ->ready >>, |
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285 | thus waking you up. |
146 | |
286 | |
147 | =cut |
287 | This makes C<schedule> I<the> generic method to use to block the current |
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288 | coroutine and wait for events: first you remember the current coroutine in |
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289 | a variable, then arrange for some callback of yours to call C<< ->ready |
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290 | >> on that once some event happens, and last you call C<schedule> to put |
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291 | yourself to sleep. Note that a lot of things can wake your coroutine up, |
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292 | so you need to check whether the event indeed happened, e.g. by storing the |
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293 | status in a variable. |
148 | |
294 | |
149 | my $prev; |
295 | See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks. |
150 | |
296 | |
151 | sub schedule { |
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152 | # should be done using priorities :( |
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153 | ($prev, $current) = ($current, shift @ready || $idle); |
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154 | Coro::State::transfer($prev, $current); |
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155 | } |
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156 | |
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157 | =item yield |
297 | =item cede |
158 | |
298 | |
159 | Yield to other processes. This function puts the current process into the |
299 | "Cede" to other coroutines. This function puts the current coroutine into |
160 | ready queue and calls C<schedule>. |
300 | the ready queue and calls C<schedule>, which has the effect of giving |
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301 | up the current "timeslice" to other coroutines of the same or higher |
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302 | priority. Once your coroutine gets its turn again it will automatically be |
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303 | resumed. |
161 | |
304 | |
162 | =cut |
305 | This function is often called C<yield> in other languages. |
163 | |
306 | |
164 | sub yield { |
307 | =item Coro::cede_notself |
165 | $current->ready; |
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166 | &schedule; |
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167 | } |
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168 | |
308 | |
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309 | Works like cede, but is not exported by default and will cede to I<any> |
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310 | coroutine, regardless of priority. This is useful sometimes to ensure |
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311 | progress is made. |
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312 | |
169 | =item terminate |
313 | =item terminate [arg...] |
170 | |
314 | |
171 | Terminates the current process. |
315 | Terminates the current coroutine with the given status values (see L<cancel>). |
172 | |
316 | |
173 | Future versions of this function will allow result arguments. |
317 | =item killall |
174 | |
318 | |
175 | =cut |
319 | Kills/terminates/cancels all coroutines except the currently running |
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320 | one. This is useful after a fork, either in the child or the parent, as |
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321 | usually only one of them should inherit the running coroutines. |
176 | |
322 | |
177 | sub terminate { |
323 | Note that while this will try to free some of the main programs resources, |
178 | $current->{_results} = [@_]; |
324 | you cannot free all of them, so if a coroutine that is not the main |
179 | &schedule; |
325 | program calls this function, there will be some one-time resource leak. |
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326 | |
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327 | =cut |
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328 | |
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329 | sub killall { |
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330 | for (Coro::State::list) { |
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331 | $_->cancel |
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332 | if $_ != $current && UNIVERSAL::isa $_, "Coro"; |
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333 | } |
180 | } |
334 | } |
181 | |
335 | |
182 | =back |
336 | =back |
183 | |
337 | |
184 | # dynamic methods |
338 | =head1 COROUTINE OBJECT METHODS |
185 | |
339 | |
186 | =head2 PROCESS METHODS |
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187 | |
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188 | These are the methods you can call on process objects. |
340 | These are the methods you can call on coroutine objects (or to create |
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341 | them). |
189 | |
342 | |
190 | =over 4 |
343 | =over 4 |
191 | |
344 | |
192 | =item new Coro \&sub [, @args...] |
345 | =item new Coro \&sub [, @args...] |
193 | |
346 | |
194 | Create a new process and return it. When the sub returns the process |
347 | Create a new coroutine and return it. When the sub returns, the coroutine |
195 | automatically terminates. To start the process you must first put it into |
348 | automatically terminates as if C<terminate> with the returned values were |
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349 | called. To make the coroutine run you must first put it into the ready |
196 | the ready queue by calling the ready method. |
350 | queue by calling the ready method. |
197 | |
351 | |
198 | The coderef you submit MUST NOT be a closure that refers to variables |
352 | See C<async> and C<Coro::State::new> for additional info about the |
199 | in an outer scope. This does NOT work. Pass arguments into it instead. |
353 | coroutine environment. |
200 | |
354 | |
201 | =cut |
355 | =cut |
202 | |
356 | |
203 | sub _newcoro { |
357 | sub _coro_run { |
204 | terminate &{+shift}; |
358 | terminate &{+shift}; |
205 | } |
359 | } |
206 | |
360 | |
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361 | =item $success = $coroutine->ready |
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362 | |
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363 | Put the given coroutine into the end of its ready queue (there is one |
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364 | queue for each priority) and return true. If the coroutine is already in |
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365 | the ready queue, do nothing and return false. |
|
|
366 | |
|
|
367 | This ensures that the scheduler will resume this coroutine automatically |
|
|
368 | once all the coroutines of higher priority and all coroutines of the same |
|
|
369 | priority that were put into the ready queue earlier have been resumed. |
|
|
370 | |
|
|
371 | =item $is_ready = $coroutine->is_ready |
|
|
372 | |
|
|
373 | Return whether the coroutine is currently the ready queue or not, |
|
|
374 | |
|
|
375 | =item $coroutine->cancel (arg...) |
|
|
376 | |
|
|
377 | Terminates the given coroutine and makes it return the given arguments as |
|
|
378 | status (default: the empty list). Never returns if the coroutine is the |
|
|
379 | current coroutine. |
|
|
380 | |
|
|
381 | =cut |
|
|
382 | |
207 | sub new { |
383 | sub cancel { |
208 | my $class = shift; |
384 | my $self = shift; |
209 | bless { |
|
|
210 | _coro_state => (new Coro::State $_[0] && \&_newcoro, @_), |
|
|
211 | }, $class; |
|
|
212 | } |
|
|
213 | |
385 | |
214 | =item $process->ready |
386 | if ($current == $self) { |
|
|
387 | terminate @_; |
|
|
388 | } else { |
|
|
389 | $self->{_status} = [@_]; |
|
|
390 | $self->_cancel; |
|
|
391 | } |
|
|
392 | } |
215 | |
393 | |
216 | Put the current process into the ready queue. |
394 | =item $coroutine->schedule_to |
217 | |
395 | |
218 | =cut |
396 | Puts the current coroutine to sleep (like C<Coro::schedule>), but instead |
|
|
397 | of continuing with the next coro from the ready queue, always switch to |
|
|
398 | the given coroutine object (regardless of priority etc.). The readyness |
|
|
399 | state of that coroutine isn't changed. |
219 | |
400 | |
220 | sub ready { |
401 | This is an advanced method for special cases - I'd love to hear about any |
221 | push @ready, $_[0]; |
402 | uses for this one. |
|
|
403 | |
|
|
404 | =item $coroutine->cede_to |
|
|
405 | |
|
|
406 | Like C<schedule_to>, but puts the current coroutine into the ready |
|
|
407 | queue. This has the effect of temporarily switching to the given |
|
|
408 | coroutine, and continuing some time later. |
|
|
409 | |
|
|
410 | This is an advanced method for special cases - I'd love to hear about any |
|
|
411 | uses for this one. |
|
|
412 | |
|
|
413 | =item $coroutine->throw ([$scalar]) |
|
|
414 | |
|
|
415 | If C<$throw> is specified and defined, it will be thrown as an exception |
|
|
416 | inside the coroutine at the next convenient point in time. Otherwise |
|
|
417 | clears the exception object. |
|
|
418 | |
|
|
419 | Coro will check for the exception each time a schedule-like-function |
|
|
420 | returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down |
|
|
421 | >>, C<< Coro::Handle->readable >> and so on. Most of these functions |
|
|
422 | detect this case and return early in case an exception is pending. |
|
|
423 | |
|
|
424 | The exception object will be thrown "as is" with the specified scalar in |
|
|
425 | C<$@>, i.e. if it is a string, no line number or newline will be appended |
|
|
426 | (unlike with C<die>). |
|
|
427 | |
|
|
428 | This can be used as a softer means than C<cancel> to ask a coroutine to |
|
|
429 | end itself, although there is no guarantee that the exception will lead to |
|
|
430 | termination, and if the exception isn't caught it might well end the whole |
|
|
431 | program. |
|
|
432 | |
|
|
433 | You might also think of C<throw> as being the moral equivalent of |
|
|
434 | C<kill>ing a coroutine with a signal (in this case, a scalar). |
|
|
435 | |
|
|
436 | =item $coroutine->join |
|
|
437 | |
|
|
438 | Wait until the coroutine terminates and return any values given to the |
|
|
439 | C<terminate> or C<cancel> functions. C<join> can be called concurrently |
|
|
440 | from multiple coroutines, and all will be resumed and given the status |
|
|
441 | return once the C<$coroutine> terminates. |
|
|
442 | |
|
|
443 | =cut |
|
|
444 | |
|
|
445 | sub join { |
|
|
446 | my $self = shift; |
|
|
447 | |
|
|
448 | unless ($self->{_status}) { |
|
|
449 | my $current = $current; |
|
|
450 | |
|
|
451 | push @{$self->{_on_destroy}}, sub { |
|
|
452 | $current->ready; |
|
|
453 | undef $current; |
|
|
454 | }; |
|
|
455 | |
|
|
456 | &schedule while $current; |
|
|
457 | } |
|
|
458 | |
|
|
459 | wantarray ? @{$self->{_status}} : $self->{_status}[0]; |
|
|
460 | } |
|
|
461 | |
|
|
462 | =item $coroutine->on_destroy (\&cb) |
|
|
463 | |
|
|
464 | Registers a callback that is called when this coroutine gets destroyed, |
|
|
465 | but before it is joined. The callback gets passed the terminate arguments, |
|
|
466 | if any, and I<must not> die, under any circumstances. |
|
|
467 | |
|
|
468 | =cut |
|
|
469 | |
|
|
470 | sub on_destroy { |
|
|
471 | my ($self, $cb) = @_; |
|
|
472 | |
|
|
473 | push @{ $self->{_on_destroy} }, $cb; |
|
|
474 | } |
|
|
475 | |
|
|
476 | =item $oldprio = $coroutine->prio ($newprio) |
|
|
477 | |
|
|
478 | Sets (or gets, if the argument is missing) the priority of the |
|
|
479 | coroutine. Higher priority coroutines get run before lower priority |
|
|
480 | coroutines. Priorities are small signed integers (currently -4 .. +3), |
|
|
481 | that you can refer to using PRIO_xxx constants (use the import tag :prio |
|
|
482 | to get then): |
|
|
483 | |
|
|
484 | PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN |
|
|
485 | 3 > 1 > 0 > -1 > -3 > -4 |
|
|
486 | |
|
|
487 | # set priority to HIGH |
|
|
488 | current->prio(PRIO_HIGH); |
|
|
489 | |
|
|
490 | The idle coroutine ($Coro::idle) always has a lower priority than any |
|
|
491 | existing coroutine. |
|
|
492 | |
|
|
493 | Changing the priority of the current coroutine will take effect immediately, |
|
|
494 | but changing the priority of coroutines in the ready queue (but not |
|
|
495 | running) will only take effect after the next schedule (of that |
|
|
496 | coroutine). This is a bug that will be fixed in some future version. |
|
|
497 | |
|
|
498 | =item $newprio = $coroutine->nice ($change) |
|
|
499 | |
|
|
500 | Similar to C<prio>, but subtract the given value from the priority (i.e. |
|
|
501 | higher values mean lower priority, just as in unix). |
|
|
502 | |
|
|
503 | =item $olddesc = $coroutine->desc ($newdesc) |
|
|
504 | |
|
|
505 | Sets (or gets in case the argument is missing) the description for this |
|
|
506 | coroutine. This is just a free-form string you can associate with a |
|
|
507 | coroutine. |
|
|
508 | |
|
|
509 | This method simply sets the C<< $coroutine->{desc} >> member to the given |
|
|
510 | string. You can modify this member directly if you wish. |
|
|
511 | |
|
|
512 | =cut |
|
|
513 | |
|
|
514 | sub desc { |
|
|
515 | my $old = $_[0]{desc}; |
|
|
516 | $_[0]{desc} = $_[1] if @_ > 1; |
|
|
517 | $old; |
|
|
518 | } |
|
|
519 | |
|
|
520 | sub transfer { |
|
|
521 | require Carp; |
|
|
522 | Carp::croak ("You must not call ->transfer on Coro objects. Use Coro::State objects or the ->schedule_to method. Caught"); |
222 | } |
523 | } |
223 | |
524 | |
224 | =back |
525 | =back |
225 | |
526 | |
|
|
527 | =head1 GLOBAL FUNCTIONS |
|
|
528 | |
|
|
529 | =over 4 |
|
|
530 | |
|
|
531 | =item Coro::nready |
|
|
532 | |
|
|
533 | Returns the number of coroutines that are currently in the ready state, |
|
|
534 | i.e. that can be switched to by calling C<schedule> directory or |
|
|
535 | indirectly. The value C<0> means that the only runnable coroutine is the |
|
|
536 | currently running one, so C<cede> would have no effect, and C<schedule> |
|
|
537 | would cause a deadlock unless there is an idle handler that wakes up some |
|
|
538 | coroutines. |
|
|
539 | |
|
|
540 | =item my $guard = Coro::guard { ... } |
|
|
541 | |
|
|
542 | This creates and returns a guard object. Nothing happens until the object |
|
|
543 | gets destroyed, in which case the codeblock given as argument will be |
|
|
544 | executed. This is useful to free locks or other resources in case of a |
|
|
545 | runtime error or when the coroutine gets canceled, as in both cases the |
|
|
546 | guard block will be executed. The guard object supports only one method, |
|
|
547 | C<< ->cancel >>, which will keep the codeblock from being executed. |
|
|
548 | |
|
|
549 | Example: set some flag and clear it again when the coroutine gets canceled |
|
|
550 | or the function returns: |
|
|
551 | |
|
|
552 | sub do_something { |
|
|
553 | my $guard = Coro::guard { $busy = 0 }; |
|
|
554 | $busy = 1; |
|
|
555 | |
|
|
556 | # do something that requires $busy to be true |
|
|
557 | } |
|
|
558 | |
|
|
559 | =cut |
|
|
560 | |
|
|
561 | sub guard(&) { |
|
|
562 | bless \(my $cb = $_[0]), "Coro::guard" |
|
|
563 | } |
|
|
564 | |
|
|
565 | sub Coro::guard::cancel { |
|
|
566 | ${$_[0]} = sub { }; |
|
|
567 | } |
|
|
568 | |
|
|
569 | sub Coro::guard::DESTROY { |
|
|
570 | ${$_[0]}->(); |
|
|
571 | } |
|
|
572 | |
|
|
573 | |
|
|
574 | =item unblock_sub { ... } |
|
|
575 | |
|
|
576 | This utility function takes a BLOCK or code reference and "unblocks" it, |
|
|
577 | returning a new coderef. Unblocking means that calling the new coderef |
|
|
578 | will return immediately without blocking, returning nothing, while the |
|
|
579 | original code ref will be called (with parameters) from within another |
|
|
580 | coroutine. |
|
|
581 | |
|
|
582 | The reason this function exists is that many event libraries (such as the |
|
|
583 | venerable L<Event|Event> module) are not coroutine-safe (a weaker form |
|
|
584 | of reentrancy). This means you must not block within event callbacks, |
|
|
585 | otherwise you might suffer from crashes or worse. The only event library |
|
|
586 | currently known that is safe to use without C<unblock_sub> is L<EV>. |
|
|
587 | |
|
|
588 | This function allows your callbacks to block by executing them in another |
|
|
589 | coroutine where it is safe to block. One example where blocking is handy |
|
|
590 | is when you use the L<Coro::AIO|Coro::AIO> functions to save results to |
|
|
591 | disk, for example. |
|
|
592 | |
|
|
593 | In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when |
|
|
594 | creating event callbacks that want to block. |
|
|
595 | |
|
|
596 | If your handler does not plan to block (e.g. simply sends a message to |
|
|
597 | another coroutine, or puts some other coroutine into the ready queue), |
|
|
598 | there is no reason to use C<unblock_sub>. |
|
|
599 | |
|
|
600 | Note that you also need to use C<unblock_sub> for any other callbacks that |
|
|
601 | are indirectly executed by any C-based event loop. For example, when you |
|
|
602 | use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it |
|
|
603 | provides callbacks that are the result of some event callback, then you |
|
|
604 | must not block either, or use C<unblock_sub>. |
|
|
605 | |
|
|
606 | =cut |
|
|
607 | |
|
|
608 | our @unblock_queue; |
|
|
609 | |
|
|
610 | # we create a special coro because we want to cede, |
|
|
611 | # to reduce pressure on the coro pool (because most callbacks |
|
|
612 | # return immediately and can be reused) and because we cannot cede |
|
|
613 | # inside an event callback. |
|
|
614 | our $unblock_scheduler = new Coro sub { |
|
|
615 | while () { |
|
|
616 | while (my $cb = pop @unblock_queue) { |
|
|
617 | &async_pool (@$cb); |
|
|
618 | |
|
|
619 | # for short-lived callbacks, this reduces pressure on the coro pool |
|
|
620 | # as the chance is very high that the async_poll coro will be back |
|
|
621 | # in the idle state when cede returns |
|
|
622 | cede; |
|
|
623 | } |
|
|
624 | schedule; # sleep well |
|
|
625 | } |
|
|
626 | }; |
|
|
627 | $unblock_scheduler->{desc} = "[unblock_sub scheduler]"; |
|
|
628 | |
|
|
629 | sub unblock_sub(&) { |
|
|
630 | my $cb = shift; |
|
|
631 | |
|
|
632 | sub { |
|
|
633 | unshift @unblock_queue, [$cb, @_]; |
|
|
634 | $unblock_scheduler->ready; |
|
|
635 | } |
|
|
636 | } |
|
|
637 | |
|
|
638 | =item $cb = Coro::rouse_cb |
|
|
639 | |
|
|
640 | Create and return a "rouse callback". That's a code reference that, |
|
|
641 | when called, will remember a copy of its arguments and notify the owner |
|
|
642 | coroutine of the callback. |
|
|
643 | |
|
|
644 | See the next function. |
|
|
645 | |
|
|
646 | =item @args = Coro::rouse_wait [$cb] |
|
|
647 | |
|
|
648 | Wait for the specified rouse callback (or the last one that was created in |
|
|
649 | this coroutine). |
|
|
650 | |
|
|
651 | As soon as the callback is invoked (or when the callback was invoked |
|
|
652 | before C<rouse_wait>), it will return the arguments originally passed to |
|
|
653 | the rouse callback. |
|
|
654 | |
|
|
655 | See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example. |
|
|
656 | |
|
|
657 | =back |
|
|
658 | |
226 | =cut |
659 | =cut |
227 | |
660 | |
228 | 1; |
661 | 1; |
229 | |
662 | |
|
|
663 | =head1 HOW TO WAIT FOR A CALLBACK |
|
|
664 | |
|
|
665 | It is very common for a coroutine to wait for some callback to be |
|
|
666 | called. This occurs naturally when you use coroutines in an otherwise |
|
|
667 | event-based program, or when you use event-based libraries. |
|
|
668 | |
|
|
669 | These typically register a callback for some event, and call that callback |
|
|
670 | when the event occured. In a coroutine, however, you typically want to |
|
|
671 | just wait for the event, simplyifying things. |
|
|
672 | |
|
|
673 | For example C<< AnyEvent->child >> registers a callback to be called when |
|
|
674 | a specific child has exited: |
|
|
675 | |
|
|
676 | my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... }); |
|
|
677 | |
|
|
678 | But from withina coroutine, you often just want to write this: |
|
|
679 | |
|
|
680 | my $status = wait_for_child $pid; |
|
|
681 | |
|
|
682 | Coro offers two functions specifically designed to make this easy, |
|
|
683 | C<Coro::rouse_cb> and C<Coro::rouse_wait>. |
|
|
684 | |
|
|
685 | The first function, C<rouse_cb>, generates and returns a callback that, |
|
|
686 | when invoked, will save its arguments and notify the coroutine that |
|
|
687 | created the callback. |
|
|
688 | |
|
|
689 | The second function, C<rouse_wait>, waits for the callback to be called |
|
|
690 | (by calling C<schedule> to go to sleep) and returns the arguments |
|
|
691 | originally passed to the callback. |
|
|
692 | |
|
|
693 | Using these functions, it becomes easy to write the C<wait_for_child> |
|
|
694 | function mentioned above: |
|
|
695 | |
|
|
696 | sub wait_for_child($) { |
|
|
697 | my ($pid) = @_; |
|
|
698 | |
|
|
699 | my $watcher = AnyEvent->child (pid => $pid, cb => Coro::rouse_cb); |
|
|
700 | |
|
|
701 | my ($rpid, $rstatus) = Coro::rouse_wait; |
|
|
702 | $rstatus |
|
|
703 | } |
|
|
704 | |
|
|
705 | In the case where C<rouse_cb> and C<rouse_wait> are not flexible enough, |
|
|
706 | you can roll your own, using C<schedule>: |
|
|
707 | |
|
|
708 | sub wait_for_child($) { |
|
|
709 | my ($pid) = @_; |
|
|
710 | |
|
|
711 | # store the current coroutine in $current, |
|
|
712 | # and provide result variables for the closure passed to ->child |
|
|
713 | my $current = $Coro::current; |
|
|
714 | my ($done, $rstatus); |
|
|
715 | |
|
|
716 | # pass a closure to ->child |
|
|
717 | my $watcher = AnyEvent->child (pid => $pid, cb => sub { |
|
|
718 | $rstatus = $_[1]; # remember rstatus |
|
|
719 | $done = 1; # mark $rstatus as valud |
|
|
720 | }); |
|
|
721 | |
|
|
722 | # wait until the closure has been called |
|
|
723 | schedule while !$done; |
|
|
724 | |
|
|
725 | $rstatus |
|
|
726 | } |
|
|
727 | |
|
|
728 | |
230 | =head1 BUGS/LIMITATIONS |
729 | =head1 BUGS/LIMITATIONS |
231 | |
730 | |
232 | - could be faster, especially when the core would introduce special |
731 | =over 4 |
233 | support for coroutines (like it does for threads). |
732 | |
234 | - there is still a memleak on coroutine termination that I could not |
733 | =item fork with pthread backend |
235 | identify. Could be as small as a single SV. |
734 | |
236 | - this module is not well-tested. |
735 | When Coro is compiled using the pthread backend (which isn't recommended |
237 | - if variables or arguments "disappear" (become undef) or become |
736 | but required on many BSDs as their libcs are completely broken), then |
238 | corrupted please contact the author so he cen iron out the |
737 | coroutines will not survive a fork. There is no known workaround except to |
239 | remaining bugs. |
738 | fix your libc and use a saner backend. |
240 | - this module is not thread-safe. You must only ever use this module from |
739 | |
241 | the same thread (this requirement might be loosened in the future to |
740 | =item perl process emulation ("threads") |
|
|
741 | |
|
|
742 | This module is not perl-pseudo-thread-safe. You should only ever use this |
|
|
743 | module from the first thread (this requirement might be removed in the |
242 | allow per-thread schedulers, but Coro::State does not yet allow this). |
744 | future to allow per-thread schedulers, but Coro::State does not yet allow |
|
|
745 | this). I recommend disabling thread support and using processes, as having |
|
|
746 | the windows process emulation enabled under unix roughly halves perl |
|
|
747 | performance, even when not used. |
|
|
748 | |
|
|
749 | =item coroutine switching not signal safe |
|
|
750 | |
|
|
751 | You must not switch to another coroutine from within a signal handler |
|
|
752 | (only relevant with %SIG - most event libraries provide safe signals). |
|
|
753 | |
|
|
754 | That means you I<MUST NOT> call any function that might "block" the |
|
|
755 | current coroutine - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or |
|
|
756 | anything that calls those. Everything else, including calling C<ready>, |
|
|
757 | works. |
|
|
758 | |
|
|
759 | =back |
|
|
760 | |
243 | |
761 | |
244 | =head1 SEE ALSO |
762 | =head1 SEE ALSO |
245 | |
763 | |
246 | L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>, |
764 | Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>. |
247 | L<Coro::Signal>, L<Coro::State>, L<Coro::Event>. |
765 | |
|
|
766 | Debugging: L<Coro::Debug>. |
|
|
767 | |
|
|
768 | Support/Utility: L<Coro::Specific>, L<Coro::Util>. |
|
|
769 | |
|
|
770 | Locking and IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, |
|
|
771 | L<Coro::SemaphoreSet>, L<Coro::RWLock>. |
|
|
772 | |
|
|
773 | I/O and Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>. |
|
|
774 | |
|
|
775 | Compatibility with other modules: L<Coro::LWP> (but see also L<AnyEvent::HTTP> for |
|
|
776 | a better-working alternative), L<Coro::BDB>, L<Coro::Storable>, |
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777 | L<Coro::Select>. |
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|
778 | |
|
|
779 | XS API: L<Coro::MakeMaker>. |
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780 | |
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781 | Low level Configuration, Thread Environment, Continuations: L<Coro::State>. |
248 | |
782 | |
249 | =head1 AUTHOR |
783 | =head1 AUTHOR |
250 | |
784 | |
251 | Marc Lehmann <pcg@goof.com> |
785 | Marc Lehmann <schmorp@schmorp.de> |
252 | http://www.goof.com/pcg/marc/ |
786 | http://home.schmorp.de/ |
253 | |
787 | |
254 | =cut |
788 | =cut |
255 | |
789 | |