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3 | Coro - coroutine process abstraction |
3 | Coro - coroutine process abstraction |
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 | cede; |
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 | This module collection manages coroutines. Coroutines are similar to |
24 | threads but don't run in parallel. |
32 | threads but don't (in general) run in parallel at the same time even |
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33 | on SMP machines. The specific flavor of coroutine used in this module |
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34 | also guarantees you that it will not switch between coroutines unless |
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35 | necessary, at easily-identified points in your program, so locking and |
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36 | parallel access are rarely an issue, making coroutine programming much |
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37 | safer and easier than threads programming. |
25 | |
38 | |
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39 | Unlike a normal perl program, however, coroutines allow you to have |
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40 | multiple running interpreters that share data, which is especially useful |
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41 | to code pseudo-parallel processes and for event-based programming, such as |
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42 | multiple HTTP-GET requests running concurrently. See L<Coro::AnyEvent> to |
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43 | learn more. |
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44 | |
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45 | Coroutines are also useful because Perl has no support for threads (the so |
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46 | called "threads" that perl offers are nothing more than the (bad) process |
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47 | emulation coming from the Windows platform: On standard operating systems |
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48 | they serve no purpose whatsoever, except by making your programs slow and |
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49 | making them use a lot of memory. Best disable them when building perl, or |
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50 | aks your software vendor/distributor to do it for you). |
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51 | |
26 | In this module, coroutines are defined as "callchain + lexical variables |
52 | In this module, coroutines are defined as "callchain + lexical variables + |
27 | + @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own |
53 | @_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain, |
28 | callchain, it's own set of lexicals and it's own set of perl's most |
54 | its own set of lexicals and its own set of perls most important global |
29 | important global variables. |
55 | variables (see L<Coro::State> for more configuration). |
30 | |
56 | |
31 | =cut |
57 | =cut |
32 | |
58 | |
33 | package Coro; |
59 | package Coro; |
34 | |
60 | |
35 | BEGIN { eval { require warnings } && warnings->unimport ("uninitialized") } |
61 | use strict qw(vars subs); |
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62 | no warnings "uninitialized"; |
36 | |
63 | |
37 | use Coro::State; |
64 | use Coro::State; |
38 | |
65 | |
39 | use vars qw($idle $main $current); |
66 | use base qw(Coro::State Exporter); |
40 | |
67 | |
41 | use base Exporter; |
68 | our $idle; # idle handler |
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69 | our $main; # main coroutine |
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70 | our $current; # current coroutine |
42 | |
71 | |
43 | $VERSION = 0.8; |
72 | our $VERSION = 5.0; |
44 | |
73 | |
45 | @EXPORT = qw(async cede schedule terminate current); |
74 | our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); |
46 | %EXPORT_TAGS = ( |
75 | our %EXPORT_TAGS = ( |
47 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
76 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
48 | ); |
77 | ); |
49 | @EXPORT_OK = @{$EXPORT_TAGS{prio}}; |
78 | our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready)); |
50 | |
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51 | { |
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52 | my @async; |
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53 | my $init; |
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54 | |
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55 | # this way of handling attributes simply is NOT scalable ;() |
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56 | sub import { |
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57 | Coro->export_to_level(1, @_); |
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58 | my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE}; |
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59 | *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub { |
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60 | my ($package, $ref) = (shift, shift); |
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61 | my @attrs; |
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62 | for (@_) { |
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63 | if ($_ eq "Coro") { |
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64 | push @async, $ref; |
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65 | unless ($init++) { |
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66 | eval q{ |
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67 | sub INIT { |
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68 | &async(pop @async) while @async; |
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69 | } |
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70 | }; |
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71 | } |
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72 | } else { |
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73 | push @attrs, $_; |
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74 | } |
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75 | } |
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76 | return $old ? $old->($package, $ref, @attrs) : @attrs; |
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77 | }; |
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78 | } |
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79 | |
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80 | } |
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81 | |
79 | |
82 | =over 4 |
80 | =over 4 |
83 | |
81 | |
84 | =item $main |
82 | =item $Coro::main |
85 | |
83 | |
86 | This coroutine represents the main program. |
84 | This variable stores the coroutine object that represents the main |
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85 | program. While you cna C<ready> it and do most other things you can do to |
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86 | coroutines, it is mainly useful to compare again C<$Coro::current>, to see |
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87 | whether you are running in the main program or not. |
87 | |
88 | |
88 | =cut |
89 | =cut |
89 | |
90 | |
90 | $main = new Coro; |
91 | # $main is now being initialised by Coro::State |
91 | |
92 | |
92 | =item $current (or as function: current) |
93 | =item $Coro::current |
93 | |
94 | |
94 | The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course). |
95 | The coroutine object representing the current coroutine (the last |
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96 | coroutine that the Coro scheduler switched to). The initial value is |
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97 | C<$Coro::main> (of course). |
95 | |
98 | |
96 | =cut |
99 | This variable is B<strictly> I<read-only>. You can take copies of the |
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100 | value stored in it and use it as any other coroutine object, but you must |
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101 | not otherwise modify the variable itself. |
97 | |
102 | |
98 | # maybe some other module used Coro::Specific before... |
103 | =cut |
99 | if ($current) { |
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100 | $main->{specific} = $current->{specific}; |
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101 | } |
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102 | |
104 | |
103 | $current = $main; |
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104 | |
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105 | sub current() { $current } |
105 | sub current() { $current } # [DEPRECATED] |
106 | |
106 | |
107 | =item $idle |
107 | =item $Coro::idle |
108 | |
108 | |
109 | The coroutine to switch to when no other coroutine is running. The default |
109 | This variable is mainly useful to integrate Coro into event loops. It is |
110 | implementation prints "FATAL: deadlock detected" and exits. |
110 | usually better to rely on L<Coro::AnyEvent> or LC<Coro::EV>, as this is |
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111 | pretty low-level functionality. |
111 | |
112 | |
112 | =cut |
113 | This variable stores a callback that is called whenever the scheduler |
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114 | finds no ready coroutines to run. The default implementation prints |
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115 | "FATAL: deadlock detected" and exits, because the program has no other way |
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116 | to continue. |
113 | |
117 | |
114 | # should be done using priorities :( |
118 | This hook is overwritten by modules such as C<Coro::Timer> and |
115 | $idle = new Coro sub { |
119 | C<Coro::AnyEvent> to wait on an external event that hopefully wake up a |
116 | print STDERR "FATAL: deadlock detected\n"; |
120 | coroutine so the scheduler can run it. |
117 | exit(51); |
121 | |
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122 | Note that the callback I<must not>, under any circumstances, block |
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123 | the current coroutine. Normally, this is achieved by having an "idle |
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124 | coroutine" that calls the event loop and then blocks again, and then |
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125 | readying that coroutine in the idle handler. |
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126 | |
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127 | See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this |
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128 | technique. |
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129 | |
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130 | Please note that if your callback recursively invokes perl (e.g. for event |
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131 | handlers), then it must be prepared to be called recursively itself. |
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132 | |
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133 | =cut |
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134 | |
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135 | $idle = sub { |
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136 | require Carp; |
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137 | Carp::croak ("FATAL: deadlock detected"); |
118 | }; |
138 | }; |
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139 | |
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140 | sub _cancel { |
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141 | my ($self) = @_; |
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142 | |
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143 | # free coroutine data and mark as destructed |
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144 | $self->_destroy |
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145 | or return; |
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146 | |
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147 | # call all destruction callbacks |
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148 | $_->(@{$self->{_status}}) |
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149 | for @{ delete $self->{_on_destroy} || [] }; |
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150 | } |
119 | |
151 | |
120 | # this coroutine is necessary because a coroutine |
152 | # this coroutine is necessary because a coroutine |
121 | # cannot destroy itself. |
153 | # cannot destroy itself. |
122 | my @destroy; |
154 | my @destroy; |
123 | my $manager; |
155 | my $manager; |
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156 | |
124 | $manager = new Coro sub { |
157 | $manager = new Coro sub { |
125 | while() { |
158 | while () { |
126 | # by overwriting the state object with the manager we destroy it |
159 | (shift @destroy)->_cancel |
127 | # while still being able to schedule this coroutine (in case it has |
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128 | # been readied multiple times. this is harmless since the manager |
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129 | # can be called as many times as neccessary and will always |
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130 | # remove itself from the runqueue |
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131 | while (@destroy) { |
160 | while @destroy; |
132 | my $coro = pop @destroy; |
161 | |
133 | $coro->{status} ||= []; |
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134 | $_->ready for @{delete $coro->{join} || []}; |
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135 | $coro->{_coro_state} = $manager->{_coro_state}; |
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136 | } |
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137 | &schedule; |
162 | &schedule; |
138 | } |
163 | } |
139 | }; |
164 | }; |
140 | |
165 | $manager->{desc} = "[coro manager]"; |
141 | # static methods. not really. |
166 | $manager->prio (PRIO_MAX); |
142 | |
167 | |
143 | =back |
168 | =back |
144 | |
169 | |
145 | =head2 STATIC METHODS |
170 | =head2 SIMPLE COROUTINE CREATION |
146 | |
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147 | Static methods are actually functions that operate on the current process only. |
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148 | |
171 | |
149 | =over 4 |
172 | =over 4 |
150 | |
173 | |
151 | =item async { ... } [@args...] |
174 | =item async { ... } [@args...] |
152 | |
175 | |
153 | Create a new asynchronous process and return it's process object |
176 | Create a new coroutine and return it's coroutine object (usually |
154 | (usually unused). When the sub returns the new process is automatically |
177 | unused). The coroutine will be put into the ready queue, so |
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178 | it will start running automatically on the next scheduler run. |
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179 | |
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180 | The first argument is a codeblock/closure that should be executed in the |
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181 | coroutine. When it returns argument returns the coroutine is automatically |
155 | terminated. |
182 | terminated. |
156 | |
183 | |
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184 | The remaining arguments are passed as arguments to the closure. |
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185 | |
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186 | See the C<Coro::State::new> constructor for info about the coroutine |
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187 | environment in which coroutines are executed. |
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188 | |
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189 | Calling C<exit> in a coroutine will do the same as calling exit outside |
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190 | the coroutine. Likewise, when the coroutine dies, the program will exit, |
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191 | just as it would in the main program. |
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192 | |
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193 | If you do not want that, you can provide a default C<die> handler, or |
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194 | simply avoid dieing (by use of C<eval>). |
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195 | |
157 | # create a new coroutine that just prints its arguments |
196 | Example: Create a new coroutine that just prints its arguments. |
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197 | |
158 | async { |
198 | async { |
159 | print "@_\n"; |
199 | print "@_\n"; |
160 | } 1,2,3,4; |
200 | } 1,2,3,4; |
161 | |
201 | |
162 | The coderef you submit MUST NOT be a closure that refers to variables |
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163 | in an outer scope. This does NOT work. Pass arguments into it instead. |
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164 | |
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165 | =cut |
202 | =cut |
166 | |
203 | |
167 | sub async(&@) { |
204 | sub async(&@) { |
168 | my $pid = new Coro @_; |
205 | my $coro = new Coro @_; |
169 | $manager->ready; # this ensures that the stack is cloned from the manager |
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170 | $pid->ready; |
206 | $coro->ready; |
171 | $pid; |
207 | $coro |
172 | } |
208 | } |
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209 | |
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210 | =item async_pool { ... } [@args...] |
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211 | |
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212 | Similar to C<async>, but uses a coroutine pool, so you should not call |
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213 | terminate or join on it (although you are allowed to), and you get a |
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214 | coroutine that might have executed other code already (which can be good |
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215 | or bad :). |
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216 | |
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217 | On the plus side, this function is faster than creating (and destroying) |
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218 | a completly new coroutine, so if you need a lot of generic coroutines in |
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219 | quick successsion, use C<async_pool>, not C<async>. |
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220 | |
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221 | The code block is executed in an C<eval> context and a warning will be |
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222 | issued in case of an exception instead of terminating the program, as |
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223 | C<async> does. As the coroutine is being reused, stuff like C<on_destroy> |
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224 | will not work in the expected way, unless you call terminate or cancel, |
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225 | which somehow defeats the purpose of pooling (but is fine in the |
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226 | exceptional case). |
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227 | |
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228 | The priority will be reset to C<0> after each run, tracing will be |
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229 | disabled, the description will be reset and the default output filehandle |
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230 | gets restored, so you can change all these. Otherwise the coroutine will |
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231 | be re-used "as-is": most notably if you change other per-coroutine global |
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232 | stuff such as C<$/> you I<must needs> revert that change, which is most |
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233 | simply done by using local as in: C<< local $/ >>. |
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234 | |
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235 | The idle pool size is limited to C<8> idle coroutines (this can be |
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236 | adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle |
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237 | coros as required. |
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238 | |
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239 | If you are concerned about pooled coroutines growing a lot because a |
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240 | single C<async_pool> used a lot of stackspace you can e.g. C<async_pool |
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241 | { terminate }> once per second or so to slowly replenish the pool. In |
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242 | addition to that, when the stacks used by a handler grows larger than 16kb |
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243 | (adjustable via $Coro::POOL_RSS) it will also be destroyed. |
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244 | |
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245 | =cut |
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246 | |
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247 | our $POOL_SIZE = 8; |
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248 | our $POOL_RSS = 16 * 1024; |
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249 | our @async_pool; |
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250 | |
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251 | sub pool_handler { |
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252 | my $cb; |
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253 | |
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254 | while () { |
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255 | eval { |
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256 | while () { |
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257 | _pool_1 $cb; |
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258 | &$cb; |
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259 | _pool_2 $cb; |
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260 | &schedule; |
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261 | } |
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262 | }; |
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263 | |
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264 | if ($@) { |
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265 | last if $@ eq "\3async_pool terminate\2\n"; |
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266 | warn $@; |
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267 | } |
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268 | } |
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269 | } |
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270 | |
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271 | sub async_pool(&@) { |
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272 | # this is also inlined into the unblock_scheduler |
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273 | my $coro = (pop @async_pool) || new Coro \&pool_handler; |
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274 | |
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275 | $coro->{_invoke} = [@_]; |
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276 | $coro->ready; |
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277 | |
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278 | $coro |
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279 | } |
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280 | |
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281 | =back |
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282 | |
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283 | =head2 STATIC METHODS |
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284 | |
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285 | Static methods are actually functions that operate on the current coroutine. |
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286 | |
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287 | =over 4 |
173 | |
288 | |
174 | =item schedule |
289 | =item schedule |
175 | |
290 | |
176 | Calls the scheduler. Please note that the current process will not be put |
291 | Calls the scheduler. The scheduler will find the next coroutine that is |
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292 | to be run from the ready queue and switches to it. The next coroutine |
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293 | to be run is simply the one with the highest priority that is longest |
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294 | in its ready queue. If there is no coroutine ready, it will clal the |
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295 | C<$Coro::idle> hook. |
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296 | |
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297 | Please note that the current coroutine will I<not> be put into the ready |
177 | into the ready queue, so calling this function usually means you will |
298 | queue, so calling this function usually means you will never be called |
178 | never be called again. |
299 | again unless something else (e.g. an event handler) calls C<< ->ready >>, |
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300 | thus waking you up. |
179 | |
301 | |
180 | =cut |
302 | This makes C<schedule> I<the> generic method to use to block the current |
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303 | coroutine and wait for events: first you remember the current coroutine in |
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304 | a variable, then arrange for some callback of yours to call C<< ->ready |
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305 | >> on that once some event happens, and last you call C<schedule> to put |
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306 | yourself to sleep. Note that a lot of things can wake your coroutine up, |
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307 | so you need to check whether the event indeed happened, e.g. by storing the |
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308 | status in a variable. |
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309 | |
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310 | The canonical way to wait on external events is this: |
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311 | |
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312 | { |
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313 | # remember current coroutine |
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314 | my $current = $Coro::current; |
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315 | |
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316 | # register a hypothetical event handler |
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317 | on_event_invoke sub { |
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318 | # wake up sleeping coroutine |
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319 | $current->ready; |
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320 | undef $current; |
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321 | }; |
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322 | |
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323 | # call schedule until event occurred. |
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324 | # in case we are woken up for other reasons |
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325 | # (current still defined), loop. |
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326 | Coro::schedule while $current; |
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327 | } |
181 | |
328 | |
182 | =item cede |
329 | =item cede |
183 | |
330 | |
184 | "Cede" to other processes. This function puts the current process into the |
331 | "Cede" to other coroutines. This function puts the current coroutine into |
185 | ready queue and calls C<schedule>, which has the effect of giving up the |
332 | the ready queue and calls C<schedule>, which has the effect of giving |
186 | current "timeslice" to other coroutines of the same or higher priority. |
333 | up the current "timeslice" to other coroutines of the same or higher |
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334 | priority. Once your coroutine gets its turn again it will automatically be |
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335 | resumed. |
187 | |
336 | |
188 | =cut |
337 | This function is often called C<yield> in other languages. |
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338 | |
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339 | =item Coro::cede_notself |
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340 | |
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341 | Works like cede, but is not exported by default and will cede to I<any> |
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342 | coroutine, regardless of priority. This is useful sometimes to ensure |
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343 | progress is made. |
189 | |
344 | |
190 | =item terminate [arg...] |
345 | =item terminate [arg...] |
191 | |
346 | |
192 | Terminates the current process. |
347 | Terminates the current coroutine with the given status values (see L<cancel>). |
193 | |
348 | |
194 | Future versions of this function will allow result arguments. |
349 | =item killall |
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350 | |
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351 | Kills/terminates/cancels all coroutines except the currently running |
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352 | one. This is useful after a fork, either in the child or the parent, as |
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353 | usually only one of them should inherit the running coroutines. |
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354 | |
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355 | Note that while this will try to free some of the main programs resources, |
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356 | you cannot free all of them, so if a coroutine that is not the main |
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357 | program calls this function, there will be some one-time resource leak. |
195 | |
358 | |
196 | =cut |
359 | =cut |
197 | |
360 | |
198 | sub terminate { |
361 | sub terminate { |
199 | $current->{status} = [@_]; |
|
|
200 | $current->cancel; |
362 | $current->cancel (@_); |
201 | &schedule; |
363 | } |
202 | die; # NORETURN |
364 | |
|
|
365 | sub killall { |
|
|
366 | for (Coro::State::list) { |
|
|
367 | $_->cancel |
|
|
368 | if $_ != $current && UNIVERSAL::isa $_, "Coro"; |
|
|
369 | } |
203 | } |
370 | } |
204 | |
371 | |
205 | =back |
372 | =back |
206 | |
373 | |
207 | # dynamic methods |
|
|
208 | |
|
|
209 | =head2 PROCESS METHODS |
374 | =head2 COROUTINE METHODS |
210 | |
375 | |
211 | These are the methods you can call on process objects. |
376 | These are the methods you can call on coroutine objects (or to create |
|
|
377 | them). |
212 | |
378 | |
213 | =over 4 |
379 | =over 4 |
214 | |
380 | |
215 | =item new Coro \&sub [, @args...] |
381 | =item new Coro \&sub [, @args...] |
216 | |
382 | |
217 | Create a new process and return it. When the sub returns the process |
383 | Create a new coroutine and return it. When the sub returns, the coroutine |
218 | automatically terminates as if C<terminate> with the returned values were |
384 | automatically terminates as if C<terminate> with the returned values were |
219 | called. To make the process run you must first put it into the ready queue |
385 | called. To make the coroutine run you must first put it into the ready |
220 | by calling the ready method. |
386 | queue by calling the ready method. |
221 | |
387 | |
222 | =cut |
388 | See C<async> and C<Coro::State::new> for additional info about the |
|
|
389 | coroutine environment. |
223 | |
390 | |
|
|
391 | =cut |
|
|
392 | |
224 | sub _newcoro { |
393 | sub _run_coro { |
225 | terminate &{+shift}; |
394 | terminate &{+shift}; |
226 | } |
395 | } |
227 | |
396 | |
228 | sub new { |
397 | sub new { |
229 | my $class = shift; |
398 | my $class = shift; |
230 | bless { |
|
|
231 | _coro_state => (new Coro::State $_[0] && \&_newcoro, @_), |
|
|
232 | }, $class; |
|
|
233 | } |
|
|
234 | |
399 | |
235 | =item $process->ready |
400 | $class->SUPER::new (\&_run_coro, @_) |
|
|
401 | } |
236 | |
402 | |
237 | Put the given process into the ready queue. |
403 | =item $success = $coroutine->ready |
238 | |
404 | |
239 | =cut |
405 | Put the given coroutine into the end of its ready queue (there is one |
|
|
406 | queue for each priority) and return true. If the coroutine is already in |
|
|
407 | the ready queue, do nothing and return false. |
240 | |
408 | |
241 | =item $process->cancel |
409 | This ensures that the scheduler will resume this coroutine automatically |
|
|
410 | once all the coroutines of higher priority and all coroutines of the same |
|
|
411 | priority that were put into the ready queue earlier have been resumed. |
242 | |
412 | |
243 | Like C<terminate>, but terminates the specified process instead. |
413 | =item $is_ready = $coroutine->is_ready |
|
|
414 | |
|
|
415 | Return whether the coroutine is currently the ready queue or not, |
|
|
416 | |
|
|
417 | =item $coroutine->cancel (arg...) |
|
|
418 | |
|
|
419 | Terminates the given coroutine and makes it return the given arguments as |
|
|
420 | status (default: the empty list). Never returns if the coroutine is the |
|
|
421 | current coroutine. |
244 | |
422 | |
245 | =cut |
423 | =cut |
246 | |
424 | |
247 | sub cancel { |
425 | sub cancel { |
|
|
426 | my $self = shift; |
|
|
427 | $self->{_status} = [@_]; |
|
|
428 | |
|
|
429 | if ($current == $self) { |
248 | push @destroy, $_[0]; |
430 | push @destroy, $self; |
249 | $manager->ready; |
431 | $manager->ready; |
250 | &schedule if $current == $_[0]; |
432 | &schedule while 1; |
|
|
433 | } else { |
|
|
434 | $self->_cancel; |
|
|
435 | } |
251 | } |
436 | } |
252 | |
437 | |
|
|
438 | =item $coroutine->throw ([$scalar]) |
|
|
439 | |
|
|
440 | If C<$throw> is specified and defined, it will be thrown as an exception |
|
|
441 | inside the coroutine at the next convenient point in time (usually after |
|
|
442 | it gains control at the next schedule/transfer/cede). Otherwise clears the |
|
|
443 | exception object. |
|
|
444 | |
|
|
445 | The exception object will be thrown "as is" with the specified scalar in |
|
|
446 | C<$@>, i.e. if it is a string, no line number or newline will be appended |
|
|
447 | (unlike with C<die>). |
|
|
448 | |
|
|
449 | This can be used as a softer means than C<cancel> to ask a coroutine to |
|
|
450 | end itself, although there is no guarantee that the exception will lead to |
|
|
451 | termination, and if the exception isn't caught it might well end the whole |
|
|
452 | program. |
|
|
453 | |
|
|
454 | You might also think of C<throw> as being the moral equivalent of |
|
|
455 | C<kill>ing a coroutine with a signal (in this case, a scalar). |
|
|
456 | |
253 | =item $process->join |
457 | =item $coroutine->join |
254 | |
458 | |
255 | Wait until the coroutine terminates and return any values given to the |
459 | Wait until the coroutine terminates and return any values given to the |
256 | C<terminate> function. C<join> can be called multiple times from multiple |
460 | C<terminate> or C<cancel> functions. C<join> can be called concurrently |
257 | processes. |
461 | from multiple coroutines, and all will be resumed and given the status |
|
|
462 | return once the C<$coroutine> terminates. |
258 | |
463 | |
259 | =cut |
464 | =cut |
260 | |
465 | |
261 | sub join { |
466 | sub join { |
262 | my $self = shift; |
467 | my $self = shift; |
|
|
468 | |
263 | unless ($self->{status}) { |
469 | unless ($self->{_status}) { |
264 | push @{$self->{join}}, $current; |
470 | my $current = $current; |
265 | &schedule; |
471 | |
|
|
472 | push @{$self->{_on_destroy}}, sub { |
|
|
473 | $current->ready; |
|
|
474 | undef $current; |
|
|
475 | }; |
|
|
476 | |
|
|
477 | &schedule while $current; |
266 | } |
478 | } |
|
|
479 | |
267 | wantarray ? @{$self->{status}} : $self->{status}[0]; |
480 | wantarray ? @{$self->{_status}} : $self->{_status}[0]; |
268 | } |
481 | } |
269 | |
482 | |
|
|
483 | =item $coroutine->on_destroy (\&cb) |
|
|
484 | |
|
|
485 | Registers a callback that is called when this coroutine gets destroyed, |
|
|
486 | but before it is joined. The callback gets passed the terminate arguments, |
|
|
487 | if any, and I<must not> die, under any circumstances. |
|
|
488 | |
|
|
489 | =cut |
|
|
490 | |
|
|
491 | sub on_destroy { |
|
|
492 | my ($self, $cb) = @_; |
|
|
493 | |
|
|
494 | push @{ $self->{_on_destroy} }, $cb; |
|
|
495 | } |
|
|
496 | |
270 | =item $oldprio = $process->prio($newprio) |
497 | =item $oldprio = $coroutine->prio ($newprio) |
271 | |
498 | |
272 | Sets (or gets, if the argument is missing) the priority of the |
499 | Sets (or gets, if the argument is missing) the priority of the |
273 | process. Higher priority processes get run before lower priority |
500 | coroutine. Higher priority coroutines get run before lower priority |
274 | processes. Priorities are small signed integers (currently -4 .. +3), |
501 | coroutines. Priorities are small signed integers (currently -4 .. +3), |
275 | that you can refer to using PRIO_xxx constants (use the import tag :prio |
502 | that you can refer to using PRIO_xxx constants (use the import tag :prio |
276 | to get then): |
503 | to get then): |
277 | |
504 | |
278 | PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN |
505 | PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN |
279 | 3 > 1 > 0 > -1 > -3 > -4 |
506 | 3 > 1 > 0 > -1 > -3 > -4 |
… | |
… | |
282 | current->prio(PRIO_HIGH); |
509 | current->prio(PRIO_HIGH); |
283 | |
510 | |
284 | The idle coroutine ($Coro::idle) always has a lower priority than any |
511 | The idle coroutine ($Coro::idle) always has a lower priority than any |
285 | existing coroutine. |
512 | existing coroutine. |
286 | |
513 | |
287 | Changing the priority of the current process will take effect immediately, |
514 | Changing the priority of the current coroutine will take effect immediately, |
288 | but changing the priority of processes in the ready queue (but not |
515 | but changing the priority of coroutines in the ready queue (but not |
289 | running) will only take effect after the next schedule (of that |
516 | running) will only take effect after the next schedule (of that |
290 | process). This is a bug that will be fixed in some future version. |
517 | coroutine). This is a bug that will be fixed in some future version. |
291 | |
518 | |
292 | =cut |
|
|
293 | |
|
|
294 | sub prio { |
|
|
295 | my $old = $_[0]{prio}; |
|
|
296 | $_[0]{prio} = $_[1] if @_ > 1; |
|
|
297 | $old; |
|
|
298 | } |
|
|
299 | |
|
|
300 | =item $newprio = $process->nice($change) |
519 | =item $newprio = $coroutine->nice ($change) |
301 | |
520 | |
302 | Similar to C<prio>, but subtract the given value from the priority (i.e. |
521 | Similar to C<prio>, but subtract the given value from the priority (i.e. |
303 | higher values mean lower priority, just as in unix). |
522 | higher values mean lower priority, just as in unix). |
304 | |
523 | |
305 | =cut |
|
|
306 | |
|
|
307 | sub nice { |
|
|
308 | $_[0]{prio} -= $_[1]; |
|
|
309 | } |
|
|
310 | |
|
|
311 | =item $olddesc = $process->desc($newdesc) |
524 | =item $olddesc = $coroutine->desc ($newdesc) |
312 | |
525 | |
313 | Sets (or gets in case the argument is missing) the description for this |
526 | Sets (or gets in case the argument is missing) the description for this |
314 | process. This is just a free-form string you can associate with a process. |
527 | coroutine. This is just a free-form string you can associate with a |
|
|
528 | coroutine. |
|
|
529 | |
|
|
530 | This method simply sets the C<< $coroutine->{desc} >> member to the given |
|
|
531 | string. You can modify this member directly if you wish. |
315 | |
532 | |
316 | =cut |
533 | =cut |
317 | |
534 | |
318 | sub desc { |
535 | sub desc { |
319 | my $old = $_[0]{desc}; |
536 | my $old = $_[0]{desc}; |
… | |
… | |
321 | $old; |
538 | $old; |
322 | } |
539 | } |
323 | |
540 | |
324 | =back |
541 | =back |
325 | |
542 | |
|
|
543 | =head2 GLOBAL FUNCTIONS |
|
|
544 | |
|
|
545 | =over 4 |
|
|
546 | |
|
|
547 | =item Coro::nready |
|
|
548 | |
|
|
549 | Returns the number of coroutines that are currently in the ready state, |
|
|
550 | i.e. that can be switched to by calling C<schedule> directory or |
|
|
551 | indirectly. The value C<0> means that the only runnable coroutine is the |
|
|
552 | currently running one, so C<cede> would have no effect, and C<schedule> |
|
|
553 | would cause a deadlock unless there is an idle handler that wakes up some |
|
|
554 | coroutines. |
|
|
555 | |
|
|
556 | =item my $guard = Coro::guard { ... } |
|
|
557 | |
|
|
558 | This creates and returns a guard object. Nothing happens until the object |
|
|
559 | gets destroyed, in which case the codeblock given as argument will be |
|
|
560 | executed. This is useful to free locks or other resources in case of a |
|
|
561 | runtime error or when the coroutine gets canceled, as in both cases the |
|
|
562 | guard block will be executed. The guard object supports only one method, |
|
|
563 | C<< ->cancel >>, which will keep the codeblock from being executed. |
|
|
564 | |
|
|
565 | Example: set some flag and clear it again when the coroutine gets canceled |
|
|
566 | or the function returns: |
|
|
567 | |
|
|
568 | sub do_something { |
|
|
569 | my $guard = Coro::guard { $busy = 0 }; |
|
|
570 | $busy = 1; |
|
|
571 | |
|
|
572 | # do something that requires $busy to be true |
|
|
573 | } |
|
|
574 | |
|
|
575 | =cut |
|
|
576 | |
|
|
577 | sub guard(&) { |
|
|
578 | bless \(my $cb = $_[0]), "Coro::guard" |
|
|
579 | } |
|
|
580 | |
|
|
581 | sub Coro::guard::cancel { |
|
|
582 | ${$_[0]} = sub { }; |
|
|
583 | } |
|
|
584 | |
|
|
585 | sub Coro::guard::DESTROY { |
|
|
586 | ${$_[0]}->(); |
|
|
587 | } |
|
|
588 | |
|
|
589 | |
|
|
590 | =item unblock_sub { ... } |
|
|
591 | |
|
|
592 | This utility function takes a BLOCK or code reference and "unblocks" it, |
|
|
593 | returning a new coderef. Unblocking means that calling the new coderef |
|
|
594 | will return immediately without blocking, returning nothing, while the |
|
|
595 | original code ref will be called (with parameters) from within another |
|
|
596 | coroutine. |
|
|
597 | |
|
|
598 | The reason this function exists is that many event libraries (such as the |
|
|
599 | venerable L<Event|Event> module) are not coroutine-safe (a weaker form |
|
|
600 | of thread-safety). This means you must not block within event callbacks, |
|
|
601 | otherwise you might suffer from crashes or worse. The only event library |
|
|
602 | currently known that is safe to use without C<unblock_sub> is L<EV>. |
|
|
603 | |
|
|
604 | This function allows your callbacks to block by executing them in another |
|
|
605 | coroutine where it is safe to block. One example where blocking is handy |
|
|
606 | is when you use the L<Coro::AIO|Coro::AIO> functions to save results to |
|
|
607 | disk, for example. |
|
|
608 | |
|
|
609 | In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when |
|
|
610 | creating event callbacks that want to block. |
|
|
611 | |
|
|
612 | If your handler does not plan to block (e.g. simply sends a message to |
|
|
613 | another coroutine, or puts some other coroutine into the ready queue), |
|
|
614 | there is no reason to use C<unblock_sub>. |
|
|
615 | |
|
|
616 | Note that you also need to use C<unblock_sub> for any other callbacks that |
|
|
617 | are indirectly executed by any C-based event loop. For example, when you |
|
|
618 | use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it |
|
|
619 | provides callbacks that are the result of some event callback, then you |
|
|
620 | must not block either, or use C<unblock_sub>. |
|
|
621 | |
|
|
622 | =cut |
|
|
623 | |
|
|
624 | our @unblock_queue; |
|
|
625 | |
|
|
626 | # we create a special coro because we want to cede, |
|
|
627 | # to reduce pressure on the coro pool (because most callbacks |
|
|
628 | # return immediately and can be reused) and because we cannot cede |
|
|
629 | # inside an event callback. |
|
|
630 | our $unblock_scheduler = new Coro sub { |
|
|
631 | while () { |
|
|
632 | while (my $cb = pop @unblock_queue) { |
|
|
633 | # this is an inlined copy of async_pool |
|
|
634 | my $coro = (pop @async_pool) || new Coro \&pool_handler; |
|
|
635 | |
|
|
636 | $coro->{_invoke} = $cb; |
|
|
637 | $coro->ready; |
|
|
638 | cede; # for short-lived callbacks, this reduces pressure on the coro pool |
|
|
639 | } |
|
|
640 | schedule; # sleep well |
|
|
641 | } |
|
|
642 | }; |
|
|
643 | $unblock_scheduler->{desc} = "[unblock_sub scheduler]"; |
|
|
644 | |
|
|
645 | sub unblock_sub(&) { |
|
|
646 | my $cb = shift; |
|
|
647 | |
|
|
648 | sub { |
|
|
649 | unshift @unblock_queue, [$cb, @_]; |
|
|
650 | $unblock_scheduler->ready; |
|
|
651 | } |
|
|
652 | } |
|
|
653 | |
|
|
654 | =back |
|
|
655 | |
326 | =cut |
656 | =cut |
327 | |
657 | |
328 | 1; |
658 | 1; |
329 | |
659 | |
330 | =head1 BUGS/LIMITATIONS |
660 | =head1 BUGS/LIMITATIONS |
331 | |
661 | |
332 | - you must make very sure that no coro is still active on global |
662 | =over 4 |
333 | destruction. very bad things might happen otherwise (usually segfaults). |
|
|
334 | |
663 | |
|
|
664 | =item fork with pthread backend |
|
|
665 | |
|
|
666 | When Coro is compiled using the pthread backend (which isn't recommended |
|
|
667 | but required on many BSDs as their libcs are completely broken), then |
|
|
668 | coroutines will not survive a fork. There is no known workaround except to |
|
|
669 | fix your libc and use a saner backend. |
|
|
670 | |
|
|
671 | =item perl process emulation ("threads") |
|
|
672 | |
335 | - this module is not thread-safe. You should only ever use this module |
673 | This module is not perl-pseudo-thread-safe. You should only ever use this |
336 | from the same thread (this requirement might be losened in the future |
674 | module from the same thread (this requirement might be removed in the |
337 | to allow per-thread schedulers, but Coro::State does not yet allow |
675 | future to allow per-thread schedulers, but Coro::State does not yet allow |
338 | this). |
676 | this). I recommend disabling thread support and using processes, as having |
|
|
677 | the windows process emulation enabled under unix roughly halves perl |
|
|
678 | performance, even when not used. |
|
|
679 | |
|
|
680 | =item coroutine switching not signal safe |
|
|
681 | |
|
|
682 | You must not switch to another coroutine from within a signal handler |
|
|
683 | (only relevant with %SIG - most event libraries provide safe signals). |
|
|
684 | |
|
|
685 | That means you I<MUST NOT> call any function that might "block" the |
|
|
686 | current coroutine - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or |
|
|
687 | anything that calls those. Everything else, including calling C<ready>, |
|
|
688 | works. |
|
|
689 | |
|
|
690 | =back |
|
|
691 | |
339 | |
692 | |
340 | =head1 SEE ALSO |
693 | =head1 SEE ALSO |
341 | |
694 | |
342 | L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>, |
695 | Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>. |
343 | L<Coro::Signal>, L<Coro::State>, L<Coro::Timer>, L<Coro::Event>, |
696 | |
344 | L<Coro::L<Coro::RWLock>, Handle>, L<Coro::Socket>. |
697 | Debugging: L<Coro::Debug>. |
|
|
698 | |
|
|
699 | Support/Utility: L<Coro::Specific>, L<Coro::Util>. |
|
|
700 | |
|
|
701 | Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>. |
|
|
702 | |
|
|
703 | IO/Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>. |
|
|
704 | |
|
|
705 | Compatibility: L<Coro::LWP>, L<Coro::BDB>, L<Coro::Storable>, L<Coro::Select>. |
|
|
706 | |
|
|
707 | XS API: L<Coro::MakeMaker>. |
|
|
708 | |
|
|
709 | Low level Configuration, Coroutine Environment: L<Coro::State>. |
345 | |
710 | |
346 | =head1 AUTHOR |
711 | =head1 AUTHOR |
347 | |
712 | |
348 | Marc Lehmann <pcg@goof.com> |
713 | Marc Lehmann <schmorp@schmorp.de> |
349 | http://www.goof.com/pcg/marc/ |
714 | http://home.schmorp.de/ |
350 | |
715 | |
351 | =cut |
716 | =cut |
352 | |
717 | |