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 | 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 | 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 | |
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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. |
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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 | |
26 | In this module, coroutines are defined as "callchain + lexical variables |
56 | In this module, a thread is defined as "callchain + lexical variables + |
27 | + @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own |
57 | @_ + $_ + $@ + $/ + C stack), that is, a thread has its own callchain, |
28 | callchain, it's own set of lexicals and it's own set of perl's most |
58 | its own set of lexicals and its own set of perls most important global |
29 | important global 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. |
30 | |
63 | |
31 | =cut |
64 | =cut |
32 | |
65 | |
33 | package Coro; |
66 | package Coro; |
34 | |
67 | |
35 | use strict; |
68 | use strict qw(vars subs); |
36 | no warnings "uninitialized"; |
69 | no warnings "uninitialized"; |
37 | |
70 | |
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71 | use Guard (); |
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72 | |
38 | use Coro::State; |
73 | use Coro::State; |
39 | |
74 | |
40 | use base Exporter::; |
75 | use base qw(Coro::State Exporter); |
41 | |
76 | |
42 | our $idle; # idle coroutine |
77 | our $idle; # idle handler |
43 | our $main; # main coroutine |
78 | our $main; # main coroutine |
44 | our $current; # current coroutine |
79 | our $current; # current coroutine |
45 | |
80 | |
46 | our $VERSION = '2.5'; |
81 | our $VERSION = 5.13; |
47 | |
82 | |
48 | our @EXPORT = qw(async cede schedule terminate current); |
83 | our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); |
49 | our %EXPORT_TAGS = ( |
84 | our %EXPORT_TAGS = ( |
50 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
85 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
51 | ); |
86 | ); |
52 | our @EXPORT_OK = @{$EXPORT_TAGS{prio}}; |
87 | our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready)); |
53 | |
88 | |
54 | { |
89 | =head1 GLOBAL VARIABLES |
55 | my @async; |
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56 | my $init; |
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57 | |
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58 | # this way of handling attributes simply is NOT scalable ;() |
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59 | sub import { |
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60 | no strict 'refs'; |
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61 | |
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62 | Coro->export_to_level(1, @_); |
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63 | |
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64 | my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE}; |
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65 | *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub { |
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66 | my ($package, $ref) = (shift, shift); |
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67 | my @attrs; |
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68 | for (@_) { |
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69 | if ($_ eq "Coro") { |
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70 | push @async, $ref; |
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71 | unless ($init++) { |
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72 | eval q{ |
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73 | sub INIT { |
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74 | &async(pop @async) while @async; |
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75 | } |
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76 | }; |
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77 | } |
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78 | } else { |
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79 | push @attrs, $_; |
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80 | } |
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81 | } |
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82 | return $old ? $old->($package, $ref, @attrs) : @attrs; |
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83 | }; |
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84 | } |
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85 | |
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86 | } |
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87 | |
90 | |
88 | =over 4 |
91 | =over 4 |
89 | |
92 | |
90 | =item $main |
93 | =item $Coro::main |
91 | |
94 | |
92 | This coroutine represents the main program. |
95 | This variable stores the coroutine object that represents the main |
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96 | program. While you cna C<ready> it and do most other things you can do to |
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97 | coroutines, it is mainly useful to compare again C<$Coro::current>, to see |
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98 | whether you are running in the main program or not. |
93 | |
99 | |
94 | =cut |
100 | =cut |
95 | |
101 | |
96 | $main = new Coro; |
102 | # $main is now being initialised by Coro::State |
97 | |
103 | |
98 | =item $current (or as function: current) |
104 | =item $Coro::current |
99 | |
105 | |
100 | The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course). |
106 | The coroutine object representing the current coroutine (the last |
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107 | coroutine that the Coro scheduler switched to). The initial value is |
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108 | C<$Coro::main> (of course). |
101 | |
109 | |
102 | =cut |
110 | This variable is B<strictly> I<read-only>. You can take copies of the |
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111 | value stored in it and use it as any other coroutine object, but you must |
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112 | not otherwise modify the variable itself. |
103 | |
113 | |
104 | # maybe some other module used Coro::Specific before... |
114 | =cut |
105 | if ($current) { |
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106 | $main->{specific} = $current->{specific}; |
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107 | } |
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108 | |
115 | |
109 | $current = $main; |
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110 | |
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111 | sub current() { $current } |
116 | sub current() { $current } # [DEPRECATED] |
112 | |
117 | |
113 | =item $idle |
118 | =item $Coro::idle |
114 | |
119 | |
115 | The coroutine to switch to when no other coroutine is running. The default |
120 | This variable is mainly useful to integrate Coro into event loops. It is |
116 | implementation prints "FATAL: deadlock detected" and exits. |
121 | usually better to rely on L<Coro::AnyEvent> or L<Coro::EV>, as this is |
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122 | pretty low-level functionality. |
117 | |
123 | |
118 | =cut |
124 | This variable stores either a coroutine or a callback. |
119 | |
125 | |
120 | # should be done using priorities :( |
126 | If it is a callback, the it is called whenever the scheduler finds no |
121 | $idle = new Coro sub { |
127 | ready coroutines to run. The default implementation prints "FATAL: |
122 | print STDERR "FATAL: deadlock detected\n"; |
128 | deadlock detected" and exits, because the program has no other way to |
123 | exit(51); |
129 | continue. |
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130 | |
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131 | If it is a coroutine object, then this object will be readied (without |
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132 | invoking any ready hooks, however) when the scheduler finds no other ready |
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133 | coroutines to run. |
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134 | |
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135 | This hook is overwritten by modules such as C<Coro::EV> and |
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136 | C<Coro::AnyEvent> to wait on an external event that hopefully wake up a |
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137 | coroutine so the scheduler can run it. |
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138 | |
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139 | Note that the callback I<must not>, under any circumstances, block |
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140 | the current coroutine. Normally, this is achieved by having an "idle |
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141 | coroutine" that calls the event loop and then blocks again, and then |
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142 | readying that coroutine in the idle handler, or by simply placing the idle |
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143 | coroutine in this variable. |
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144 | |
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145 | See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this |
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146 | technique. |
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147 | |
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148 | Please note that if your callback recursively invokes perl (e.g. for event |
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149 | handlers), then it must be prepared to be called recursively itself. |
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150 | |
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151 | =cut |
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152 | |
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153 | $idle = sub { |
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154 | require Carp; |
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155 | Carp::croak ("FATAL: deadlock detected"); |
124 | }; |
156 | }; |
125 | |
157 | |
126 | # this coroutine is necessary because a coroutine |
158 | # this coroutine is necessary because a coroutine |
127 | # cannot destroy itself. |
159 | # cannot destroy itself. |
128 | my @destroy; |
160 | our @destroy; |
129 | my $manager; |
161 | our $manager; |
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162 | |
130 | $manager = new Coro sub { |
163 | $manager = new Coro sub { |
131 | while () { |
164 | while () { |
132 | # by overwriting the state object with the manager we destroy it |
165 | Coro::_cancel shift @destroy |
133 | # while still being able to schedule this coroutine (in case it has |
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134 | # been readied multiple times. this is harmless since the manager |
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135 | # can be called as many times as neccessary and will always |
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136 | # remove itself from the runqueue |
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137 | while (@destroy) { |
166 | while @destroy; |
138 | my $coro = pop @destroy; |
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139 | $coro->{status} ||= []; |
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140 | $_->ready for @{delete $coro->{join} || []}; |
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141 | |
167 | |
142 | # the next line destroys the _coro_state, but keeps the |
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143 | # process itself intact (we basically make it a zombie |
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144 | # process that always runs the manager thread, so it's possible |
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145 | # to transfer() to this process). |
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146 | $coro->{_coro_state} = $manager->{_coro_state}; |
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147 | } |
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148 | &schedule; |
168 | &schedule; |
149 | } |
169 | } |
150 | }; |
170 | }; |
151 | |
171 | $manager->{desc} = "[coro manager]"; |
152 | # static methods. not really. |
172 | $manager->prio (PRIO_MAX); |
153 | |
173 | |
154 | =back |
174 | =back |
155 | |
175 | |
156 | =head2 STATIC METHODS |
176 | =head1 SIMPLE COROUTINE CREATION |
157 | |
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158 | Static methods are actually functions that operate on the current process only. |
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159 | |
177 | |
160 | =over 4 |
178 | =over 4 |
161 | |
179 | |
162 | =item async { ... } [@args...] |
180 | =item async { ... } [@args...] |
163 | |
181 | |
164 | Create a new asynchronous process and return it's process object |
182 | Create a new coroutine and return its coroutine object (usually |
165 | (usually unused). When the sub returns the new process is automatically |
183 | unused). The coroutine will be put into the ready queue, so |
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184 | it will start running automatically on the next scheduler run. |
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185 | |
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186 | The first argument is a codeblock/closure that should be executed in the |
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187 | coroutine. When it returns argument returns the coroutine is automatically |
166 | terminated. |
188 | terminated. |
167 | |
189 | |
168 | When the coroutine dies, the program will exit, just as in the main |
190 | The remaining arguments are passed as arguments to the closure. |
169 | program. |
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170 | |
191 | |
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192 | See the C<Coro::State::new> constructor for info about the coroutine |
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193 | environment in which coroutines are executed. |
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194 | |
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195 | Calling C<exit> in a coroutine will do the same as calling exit outside |
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196 | the coroutine. Likewise, when the coroutine dies, the program will exit, |
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197 | just as it would in the main program. |
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198 | |
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199 | If you do not want that, you can provide a default C<die> handler, or |
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200 | simply avoid dieing (by use of C<eval>). |
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201 | |
171 | # create a new coroutine that just prints its arguments |
202 | Example: Create a new coroutine that just prints its arguments. |
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203 | |
172 | async { |
204 | async { |
173 | print "@_\n"; |
205 | print "@_\n"; |
174 | } 1,2,3,4; |
206 | } 1,2,3,4; |
175 | |
207 | |
176 | =cut |
208 | =cut |
177 | |
209 | |
178 | sub async(&@) { |
210 | sub async(&@) { |
179 | my $pid = new Coro @_; |
211 | my $coro = new Coro @_; |
180 | $manager->ready; # this ensures that the stack is cloned from the manager |
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181 | $pid->ready; |
212 | $coro->ready; |
182 | $pid; |
213 | $coro |
183 | } |
214 | } |
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215 | |
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216 | =item async_pool { ... } [@args...] |
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217 | |
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218 | Similar to C<async>, but uses a coroutine pool, so you should not call |
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219 | terminate or join on it (although you are allowed to), and you get a |
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220 | coroutine that might have executed other code already (which can be good |
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221 | or bad :). |
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222 | |
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223 | On the plus side, this function is about twice as fast as creating (and |
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224 | destroying) a completely new coroutine, so if you need a lot of generic |
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225 | coroutines in quick successsion, use C<async_pool>, not C<async>. |
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226 | |
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227 | The code block is executed in an C<eval> context and a warning will be |
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228 | issued in case of an exception instead of terminating the program, as |
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229 | C<async> does. As the coroutine is being reused, stuff like C<on_destroy> |
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230 | will not work in the expected way, unless you call terminate or cancel, |
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231 | which somehow defeats the purpose of pooling (but is fine in the |
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232 | exceptional case). |
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233 | |
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234 | The priority will be reset to C<0> after each run, tracing will be |
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235 | disabled, the description will be reset and the default output filehandle |
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236 | gets restored, so you can change all these. Otherwise the coroutine will |
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237 | be re-used "as-is": most notably if you change other per-coroutine global |
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238 | stuff such as C<$/> you I<must needs> revert that change, which is most |
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239 | simply done by using local as in: C<< local $/ >>. |
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240 | |
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241 | The idle pool size is limited to C<8> idle coroutines (this can be |
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242 | adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle |
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243 | coros as required. |
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244 | |
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245 | If you are concerned about pooled coroutines growing a lot because a |
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246 | single C<async_pool> used a lot of stackspace you can e.g. C<async_pool |
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247 | { terminate }> once per second or so to slowly replenish the pool. In |
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248 | addition to that, when the stacks used by a handler grows larger than 32kb |
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249 | (adjustable via $Coro::POOL_RSS) it will also be destroyed. |
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250 | |
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251 | =cut |
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252 | |
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253 | our $POOL_SIZE = 8; |
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254 | our $POOL_RSS = 32 * 1024; |
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255 | our @async_pool; |
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256 | |
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257 | sub pool_handler { |
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258 | while () { |
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259 | eval { |
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260 | &{&_pool_handler} while 1; |
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261 | }; |
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262 | |
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263 | warn $@ if $@; |
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264 | } |
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265 | } |
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266 | |
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267 | =back |
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268 | |
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269 | =head1 STATIC METHODS |
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270 | |
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271 | Static methods are actually functions that implicitly operate on the |
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272 | current coroutine. |
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273 | |
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274 | =over 4 |
184 | |
275 | |
185 | =item schedule |
276 | =item schedule |
186 | |
277 | |
187 | Calls the scheduler. Please note that the current process will not be put |
278 | Calls the scheduler. The scheduler will find the next coroutine that is |
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279 | to be run from the ready queue and switches to it. The next coroutine |
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280 | to be run is simply the one with the highest priority that is longest |
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281 | in its ready queue. If there is no coroutine ready, it will clal the |
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282 | C<$Coro::idle> hook. |
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283 | |
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284 | Please note that the current coroutine will I<not> be put into the ready |
188 | into the ready queue, so calling this function usually means you will |
285 | queue, so calling this function usually means you will never be called |
189 | never be called again. |
286 | again unless something else (e.g. an event handler) calls C<< ->ready >>, |
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287 | thus waking you up. |
190 | |
288 | |
191 | =cut |
289 | This makes C<schedule> I<the> generic method to use to block the current |
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290 | coroutine and wait for events: first you remember the current coroutine in |
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291 | a variable, then arrange for some callback of yours to call C<< ->ready |
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292 | >> on that once some event happens, and last you call C<schedule> to put |
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293 | yourself to sleep. Note that a lot of things can wake your coroutine up, |
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294 | so you need to check whether the event indeed happened, e.g. by storing the |
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295 | status in a variable. |
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296 | |
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297 | See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks. |
192 | |
298 | |
193 | =item cede |
299 | =item cede |
194 | |
300 | |
195 | "Cede" to other processes. This function puts the current process into the |
301 | "Cede" to other coroutines. This function puts the current coroutine into |
196 | ready queue and calls C<schedule>, which has the effect of giving up the |
302 | the ready queue and calls C<schedule>, which has the effect of giving |
197 | current "timeslice" to other coroutines of the same or higher priority. |
303 | up the current "timeslice" to other coroutines of the same or higher |
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304 | priority. Once your coroutine gets its turn again it will automatically be |
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305 | resumed. |
198 | |
306 | |
199 | =cut |
307 | This function is often called C<yield> in other languages. |
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308 | |
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309 | =item Coro::cede_notself |
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310 | |
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311 | Works like cede, but is not exported by default and will cede to I<any> |
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312 | coroutine, regardless of priority. This is useful sometimes to ensure |
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313 | progress is made. |
200 | |
314 | |
201 | =item terminate [arg...] |
315 | =item terminate [arg...] |
202 | |
316 | |
203 | Terminates the current process with the given status values (see L<cancel>). |
317 | Terminates the current coroutine with the given status values (see L<cancel>). |
204 | |
318 | |
205 | =cut |
319 | =item killall |
206 | |
320 | |
207 | sub terminate { |
321 | Kills/terminates/cancels all coroutines except the currently running |
208 | $current->cancel (@_); |
322 | one. This can be useful after a fork, either in the child or the parent, |
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323 | as usually only one of them should inherit the running coroutines. |
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324 | |
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325 | Note that in the implementation, destructors run as normal, making this |
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326 | function not so useful after a fork. Future versions of this function |
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327 | might try to free resources without running any code. |
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328 | |
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329 | Note that while this will try to free some of the main programs resources, |
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330 | you cannot free all of them, so if a coroutine that is not the main |
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331 | program calls this function, there will be some one-time resource leak. |
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332 | |
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333 | =cut |
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334 | |
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335 | sub killall { |
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336 | for (Coro::State::list) { |
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337 | $_->cancel |
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338 | if $_ != $current && UNIVERSAL::isa $_, "Coro"; |
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339 | } |
209 | } |
340 | } |
210 | |
341 | |
211 | =back |
342 | =back |
212 | |
343 | |
213 | # dynamic methods |
344 | =head1 COROUTINE OBJECT METHODS |
214 | |
345 | |
215 | =head2 PROCESS METHODS |
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216 | |
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217 | These are the methods you can call on process objects. |
346 | These are the methods you can call on coroutine objects (or to create |
|
|
347 | them). |
218 | |
348 | |
219 | =over 4 |
349 | =over 4 |
220 | |
350 | |
221 | =item new Coro \&sub [, @args...] |
351 | =item new Coro \&sub [, @args...] |
222 | |
352 | |
223 | Create a new process and return it. When the sub returns the process |
353 | Create a new coroutine and return it. When the sub returns, the coroutine |
224 | automatically terminates as if C<terminate> with the returned values were |
354 | automatically terminates as if C<terminate> with the returned values were |
225 | called. To make the process run you must first put it into the ready queue |
355 | called. To make the coroutine run you must first put it into the ready |
226 | by calling the ready method. |
356 | queue by calling the ready method. |
227 | |
357 | |
228 | =cut |
358 | See C<async> and C<Coro::State::new> for additional info about the |
|
|
359 | coroutine environment. |
229 | |
360 | |
|
|
361 | =cut |
|
|
362 | |
230 | sub _newcoro { |
363 | sub _coro_run { |
231 | terminate &{+shift}; |
364 | terminate &{+shift}; |
232 | } |
365 | } |
233 | |
366 | |
234 | sub new { |
367 | =item $success = $coroutine->ready |
235 | my $class = shift; |
|
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236 | bless { |
|
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237 | _coro_state => (new Coro::State $_[0] && \&_newcoro, @_), |
|
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238 | }, $class; |
|
|
239 | } |
|
|
240 | |
368 | |
241 | =item $process->ready |
369 | Put the given coroutine into the end of its ready queue (there is one |
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370 | queue for each priority) and return true. If the coroutine is already in |
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371 | the ready queue, do nothing and return false. |
242 | |
372 | |
243 | Put the given process into the ready queue. |
373 | This ensures that the scheduler will resume this coroutine automatically |
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|
374 | once all the coroutines of higher priority and all coroutines of the same |
|
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375 | priority that were put into the ready queue earlier have been resumed. |
244 | |
376 | |
245 | =cut |
377 | =item $is_ready = $coroutine->is_ready |
246 | |
378 | |
|
|
379 | Return whether the coroutine is currently the ready queue or not, |
|
|
380 | |
247 | =item $process->cancel (arg...) |
381 | =item $coroutine->cancel (arg...) |
248 | |
382 | |
249 | Terminates the given process and makes it return the given arguments as |
383 | Terminates the given coroutine and makes it return the given arguments as |
250 | status (default: the empty list). |
384 | status (default: the empty list). Never returns if the coroutine is the |
|
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385 | current coroutine. |
251 | |
386 | |
252 | =cut |
387 | =cut |
253 | |
388 | |
254 | sub cancel { |
389 | sub cancel { |
255 | my $self = shift; |
390 | my $self = shift; |
|
|
391 | |
|
|
392 | if ($current == $self) { |
|
|
393 | terminate @_; |
|
|
394 | } else { |
256 | $self->{status} = [@_]; |
395 | $self->{_status} = [@_]; |
257 | push @destroy, $self; |
396 | $self->_cancel; |
258 | $manager->ready; |
397 | } |
259 | &schedule if $current == $self; |
|
|
260 | } |
398 | } |
261 | |
399 | |
|
|
400 | =item $coroutine->schedule_to |
|
|
401 | |
|
|
402 | Puts the current coroutine to sleep (like C<Coro::schedule>), but instead |
|
|
403 | of continuing with the next coro from the ready queue, always switch to |
|
|
404 | the given coroutine object (regardless of priority etc.). The readyness |
|
|
405 | state of that coroutine isn't changed. |
|
|
406 | |
|
|
407 | This is an advanced method for special cases - I'd love to hear about any |
|
|
408 | uses for this one. |
|
|
409 | |
|
|
410 | =item $coroutine->cede_to |
|
|
411 | |
|
|
412 | Like C<schedule_to>, but puts the current coroutine into the ready |
|
|
413 | queue. This has the effect of temporarily switching to the given |
|
|
414 | coroutine, and continuing some time later. |
|
|
415 | |
|
|
416 | This is an advanced method for special cases - I'd love to hear about any |
|
|
417 | uses for this one. |
|
|
418 | |
|
|
419 | =item $coroutine->throw ([$scalar]) |
|
|
420 | |
|
|
421 | If C<$throw> is specified and defined, it will be thrown as an exception |
|
|
422 | inside the coroutine at the next convenient point in time. Otherwise |
|
|
423 | clears the exception object. |
|
|
424 | |
|
|
425 | Coro will check for the exception each time a schedule-like-function |
|
|
426 | returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down |
|
|
427 | >>, C<< Coro::Handle->readable >> and so on. Most of these functions |
|
|
428 | detect this case and return early in case an exception is pending. |
|
|
429 | |
|
|
430 | The exception object will be thrown "as is" with the specified scalar in |
|
|
431 | C<$@>, i.e. if it is a string, no line number or newline will be appended |
|
|
432 | (unlike with C<die>). |
|
|
433 | |
|
|
434 | This can be used as a softer means than C<cancel> to ask a coroutine to |
|
|
435 | end itself, although there is no guarantee that the exception will lead to |
|
|
436 | termination, and if the exception isn't caught it might well end the whole |
|
|
437 | program. |
|
|
438 | |
|
|
439 | You might also think of C<throw> as being the moral equivalent of |
|
|
440 | C<kill>ing a coroutine with a signal (in this case, a scalar). |
|
|
441 | |
262 | =item $process->join |
442 | =item $coroutine->join |
263 | |
443 | |
264 | Wait until the coroutine terminates and return any values given to the |
444 | Wait until the coroutine terminates and return any values given to the |
265 | C<terminate> or C<cancel> functions. C<join> can be called multiple times |
445 | C<terminate> or C<cancel> functions. C<join> can be called concurrently |
266 | from multiple processes. |
446 | from multiple coroutines, and all will be resumed and given the status |
|
|
447 | return once the C<$coroutine> terminates. |
267 | |
448 | |
268 | =cut |
449 | =cut |
269 | |
450 | |
270 | sub join { |
451 | sub join { |
271 | my $self = shift; |
452 | my $self = shift; |
|
|
453 | |
272 | unless ($self->{status}) { |
454 | unless ($self->{_status}) { |
273 | push @{$self->{join}}, $current; |
455 | my $current = $current; |
274 | &schedule; |
456 | |
|
|
457 | push @{$self->{_on_destroy}}, sub { |
|
|
458 | $current->ready; |
|
|
459 | undef $current; |
|
|
460 | }; |
|
|
461 | |
|
|
462 | &schedule while $current; |
275 | } |
463 | } |
|
|
464 | |
276 | wantarray ? @{$self->{status}} : $self->{status}[0]; |
465 | wantarray ? @{$self->{_status}} : $self->{_status}[0]; |
277 | } |
466 | } |
278 | |
467 | |
|
|
468 | =item $coroutine->on_destroy (\&cb) |
|
|
469 | |
|
|
470 | Registers a callback that is called when this coroutine gets destroyed, |
|
|
471 | but before it is joined. The callback gets passed the terminate arguments, |
|
|
472 | if any, and I<must not> die, under any circumstances. |
|
|
473 | |
|
|
474 | =cut |
|
|
475 | |
|
|
476 | sub on_destroy { |
|
|
477 | my ($self, $cb) = @_; |
|
|
478 | |
|
|
479 | push @{ $self->{_on_destroy} }, $cb; |
|
|
480 | } |
|
|
481 | |
279 | =item $oldprio = $process->prio($newprio) |
482 | =item $oldprio = $coroutine->prio ($newprio) |
280 | |
483 | |
281 | Sets (or gets, if the argument is missing) the priority of the |
484 | Sets (or gets, if the argument is missing) the priority of the |
282 | process. Higher priority processes get run before lower priority |
485 | coroutine. Higher priority coroutines get run before lower priority |
283 | processes. Priorities are small signed integers (currently -4 .. +3), |
486 | coroutines. Priorities are small signed integers (currently -4 .. +3), |
284 | that you can refer to using PRIO_xxx constants (use the import tag :prio |
487 | that you can refer to using PRIO_xxx constants (use the import tag :prio |
285 | to get then): |
488 | to get then): |
286 | |
489 | |
287 | PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN |
490 | PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN |
288 | 3 > 1 > 0 > -1 > -3 > -4 |
491 | 3 > 1 > 0 > -1 > -3 > -4 |
… | |
… | |
291 | current->prio(PRIO_HIGH); |
494 | current->prio(PRIO_HIGH); |
292 | |
495 | |
293 | The idle coroutine ($Coro::idle) always has a lower priority than any |
496 | The idle coroutine ($Coro::idle) always has a lower priority than any |
294 | existing coroutine. |
497 | existing coroutine. |
295 | |
498 | |
296 | Changing the priority of the current process will take effect immediately, |
499 | Changing the priority of the current coroutine will take effect immediately, |
297 | but changing the priority of processes in the ready queue (but not |
500 | but changing the priority of coroutines in the ready queue (but not |
298 | running) will only take effect after the next schedule (of that |
501 | running) will only take effect after the next schedule (of that |
299 | process). This is a bug that will be fixed in some future version. |
502 | coroutine). This is a bug that will be fixed in some future version. |
300 | |
503 | |
301 | =cut |
|
|
302 | |
|
|
303 | sub prio { |
|
|
304 | my $old = $_[0]{prio}; |
|
|
305 | $_[0]{prio} = $_[1] if @_ > 1; |
|
|
306 | $old; |
|
|
307 | } |
|
|
308 | |
|
|
309 | =item $newprio = $process->nice($change) |
504 | =item $newprio = $coroutine->nice ($change) |
310 | |
505 | |
311 | Similar to C<prio>, but subtract the given value from the priority (i.e. |
506 | Similar to C<prio>, but subtract the given value from the priority (i.e. |
312 | higher values mean lower priority, just as in unix). |
507 | higher values mean lower priority, just as in unix). |
313 | |
508 | |
314 | =cut |
|
|
315 | |
|
|
316 | sub nice { |
|
|
317 | $_[0]{prio} -= $_[1]; |
|
|
318 | } |
|
|
319 | |
|
|
320 | =item $olddesc = $process->desc($newdesc) |
509 | =item $olddesc = $coroutine->desc ($newdesc) |
321 | |
510 | |
322 | Sets (or gets in case the argument is missing) the description for this |
511 | Sets (or gets in case the argument is missing) the description for this |
323 | process. This is just a free-form string you can associate with a process. |
512 | coroutine. This is just a free-form string you can associate with a |
|
|
513 | coroutine. |
|
|
514 | |
|
|
515 | This method simply sets the C<< $coroutine->{desc} >> member to the given |
|
|
516 | string. You can modify this member directly if you wish. |
324 | |
517 | |
325 | =cut |
518 | =cut |
326 | |
519 | |
327 | sub desc { |
520 | sub desc { |
328 | my $old = $_[0]{desc}; |
521 | my $old = $_[0]{desc}; |
329 | $_[0]{desc} = $_[1] if @_ > 1; |
522 | $_[0]{desc} = $_[1] if @_ > 1; |
330 | $old; |
523 | $old; |
331 | } |
524 | } |
332 | |
525 | |
|
|
526 | sub transfer { |
|
|
527 | require Carp; |
|
|
528 | Carp::croak ("You must not call ->transfer on Coro objects. Use Coro::State objects or the ->schedule_to method. Caught"); |
|
|
529 | } |
|
|
530 | |
333 | =back |
531 | =back |
334 | |
532 | |
|
|
533 | =head1 GLOBAL FUNCTIONS |
|
|
534 | |
|
|
535 | =over 4 |
|
|
536 | |
|
|
537 | =item Coro::nready |
|
|
538 | |
|
|
539 | Returns the number of coroutines that are currently in the ready state, |
|
|
540 | i.e. that can be switched to by calling C<schedule> directory or |
|
|
541 | indirectly. The value C<0> means that the only runnable coroutine is the |
|
|
542 | currently running one, so C<cede> would have no effect, and C<schedule> |
|
|
543 | would cause a deadlock unless there is an idle handler that wakes up some |
|
|
544 | coroutines. |
|
|
545 | |
|
|
546 | =item my $guard = Coro::guard { ... } |
|
|
547 | |
|
|
548 | This function still exists, but is deprecated. Please use the |
|
|
549 | C<Guard::guard> function instead. |
|
|
550 | |
|
|
551 | =cut |
|
|
552 | |
|
|
553 | BEGIN { *guard = \&Guard::guard } |
|
|
554 | |
|
|
555 | =item unblock_sub { ... } |
|
|
556 | |
|
|
557 | This utility function takes a BLOCK or code reference and "unblocks" it, |
|
|
558 | returning a new coderef. Unblocking means that calling the new coderef |
|
|
559 | will return immediately without blocking, returning nothing, while the |
|
|
560 | original code ref will be called (with parameters) from within another |
|
|
561 | coroutine. |
|
|
562 | |
|
|
563 | The reason this function exists is that many event libraries (such as the |
|
|
564 | venerable L<Event|Event> module) are not coroutine-safe (a weaker form |
|
|
565 | of reentrancy). This means you must not block within event callbacks, |
|
|
566 | otherwise you might suffer from crashes or worse. The only event library |
|
|
567 | currently known that is safe to use without C<unblock_sub> is L<EV>. |
|
|
568 | |
|
|
569 | This function allows your callbacks to block by executing them in another |
|
|
570 | coroutine where it is safe to block. One example where blocking is handy |
|
|
571 | is when you use the L<Coro::AIO|Coro::AIO> functions to save results to |
|
|
572 | disk, for example. |
|
|
573 | |
|
|
574 | In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when |
|
|
575 | creating event callbacks that want to block. |
|
|
576 | |
|
|
577 | If your handler does not plan to block (e.g. simply sends a message to |
|
|
578 | another coroutine, or puts some other coroutine into the ready queue), |
|
|
579 | there is no reason to use C<unblock_sub>. |
|
|
580 | |
|
|
581 | Note that you also need to use C<unblock_sub> for any other callbacks that |
|
|
582 | are indirectly executed by any C-based event loop. For example, when you |
|
|
583 | use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it |
|
|
584 | provides callbacks that are the result of some event callback, then you |
|
|
585 | must not block either, or use C<unblock_sub>. |
|
|
586 | |
|
|
587 | =cut |
|
|
588 | |
|
|
589 | our @unblock_queue; |
|
|
590 | |
|
|
591 | # we create a special coro because we want to cede, |
|
|
592 | # to reduce pressure on the coro pool (because most callbacks |
|
|
593 | # return immediately and can be reused) and because we cannot cede |
|
|
594 | # inside an event callback. |
|
|
595 | our $unblock_scheduler = new Coro sub { |
|
|
596 | while () { |
|
|
597 | while (my $cb = pop @unblock_queue) { |
|
|
598 | &async_pool (@$cb); |
|
|
599 | |
|
|
600 | # for short-lived callbacks, this reduces pressure on the coro pool |
|
|
601 | # as the chance is very high that the async_poll coro will be back |
|
|
602 | # in the idle state when cede returns |
|
|
603 | cede; |
|
|
604 | } |
|
|
605 | schedule; # sleep well |
|
|
606 | } |
|
|
607 | }; |
|
|
608 | $unblock_scheduler->{desc} = "[unblock_sub scheduler]"; |
|
|
609 | |
|
|
610 | sub unblock_sub(&) { |
|
|
611 | my $cb = shift; |
|
|
612 | |
|
|
613 | sub { |
|
|
614 | unshift @unblock_queue, [$cb, @_]; |
|
|
615 | $unblock_scheduler->ready; |
|
|
616 | } |
|
|
617 | } |
|
|
618 | |
|
|
619 | =item $cb = Coro::rouse_cb |
|
|
620 | |
|
|
621 | Create and return a "rouse callback". That's a code reference that, |
|
|
622 | when called, will remember a copy of its arguments and notify the owner |
|
|
623 | coroutine of the callback. |
|
|
624 | |
|
|
625 | See the next function. |
|
|
626 | |
|
|
627 | =item @args = Coro::rouse_wait [$cb] |
|
|
628 | |
|
|
629 | Wait for the specified rouse callback (or the last one that was created in |
|
|
630 | this coroutine). |
|
|
631 | |
|
|
632 | As soon as the callback is invoked (or when the callback was invoked |
|
|
633 | before C<rouse_wait>), it will return the arguments originally passed to |
|
|
634 | the rouse callback. |
|
|
635 | |
|
|
636 | See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example. |
|
|
637 | |
|
|
638 | =back |
|
|
639 | |
335 | =cut |
640 | =cut |
336 | |
641 | |
337 | 1; |
642 | 1; |
338 | |
643 | |
|
|
644 | =head1 HOW TO WAIT FOR A CALLBACK |
|
|
645 | |
|
|
646 | It is very common for a coroutine to wait for some callback to be |
|
|
647 | called. This occurs naturally when you use coroutines in an otherwise |
|
|
648 | event-based program, or when you use event-based libraries. |
|
|
649 | |
|
|
650 | These typically register a callback for some event, and call that callback |
|
|
651 | when the event occured. In a coroutine, however, you typically want to |
|
|
652 | just wait for the event, simplyifying things. |
|
|
653 | |
|
|
654 | For example C<< AnyEvent->child >> registers a callback to be called when |
|
|
655 | a specific child has exited: |
|
|
656 | |
|
|
657 | my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... }); |
|
|
658 | |
|
|
659 | But from withina coroutine, you often just want to write this: |
|
|
660 | |
|
|
661 | my $status = wait_for_child $pid; |
|
|
662 | |
|
|
663 | Coro offers two functions specifically designed to make this easy, |
|
|
664 | C<Coro::rouse_cb> and C<Coro::rouse_wait>. |
|
|
665 | |
|
|
666 | The first function, C<rouse_cb>, generates and returns a callback that, |
|
|
667 | when invoked, will save its arguments and notify the coroutine that |
|
|
668 | created the callback. |
|
|
669 | |
|
|
670 | The second function, C<rouse_wait>, waits for the callback to be called |
|
|
671 | (by calling C<schedule> to go to sleep) and returns the arguments |
|
|
672 | originally passed to the callback. |
|
|
673 | |
|
|
674 | Using these functions, it becomes easy to write the C<wait_for_child> |
|
|
675 | function mentioned above: |
|
|
676 | |
|
|
677 | sub wait_for_child($) { |
|
|
678 | my ($pid) = @_; |
|
|
679 | |
|
|
680 | my $watcher = AnyEvent->child (pid => $pid, cb => Coro::rouse_cb); |
|
|
681 | |
|
|
682 | my ($rpid, $rstatus) = Coro::rouse_wait; |
|
|
683 | $rstatus |
|
|
684 | } |
|
|
685 | |
|
|
686 | In the case where C<rouse_cb> and C<rouse_wait> are not flexible enough, |
|
|
687 | you can roll your own, using C<schedule>: |
|
|
688 | |
|
|
689 | sub wait_for_child($) { |
|
|
690 | my ($pid) = @_; |
|
|
691 | |
|
|
692 | # store the current coroutine in $current, |
|
|
693 | # and provide result variables for the closure passed to ->child |
|
|
694 | my $current = $Coro::current; |
|
|
695 | my ($done, $rstatus); |
|
|
696 | |
|
|
697 | # pass a closure to ->child |
|
|
698 | my $watcher = AnyEvent->child (pid => $pid, cb => sub { |
|
|
699 | $rstatus = $_[1]; # remember rstatus |
|
|
700 | $done = 1; # mark $rstatus as valud |
|
|
701 | }); |
|
|
702 | |
|
|
703 | # wait until the closure has been called |
|
|
704 | schedule while !$done; |
|
|
705 | |
|
|
706 | $rstatus |
|
|
707 | } |
|
|
708 | |
|
|
709 | |
339 | =head1 BUGS/LIMITATIONS |
710 | =head1 BUGS/LIMITATIONS |
340 | |
711 | |
341 | - you must make very sure that no coro is still active on global |
712 | =over 4 |
342 | destruction. very bad things might happen otherwise (usually segfaults). |
|
|
343 | |
713 | |
|
|
714 | =item fork with pthread backend |
|
|
715 | |
|
|
716 | When Coro is compiled using the pthread backend (which isn't recommended |
|
|
717 | but required on many BSDs as their libcs are completely broken), then |
|
|
718 | coroutines will not survive a fork. There is no known workaround except to |
|
|
719 | fix your libc and use a saner backend. |
|
|
720 | |
|
|
721 | =item perl process emulation ("threads") |
|
|
722 | |
344 | - this module is not thread-safe. You should only ever use this module |
723 | This module is not perl-pseudo-thread-safe. You should only ever use this |
345 | from the same thread (this requirement might be losened in the future |
724 | module from the first thread (this requirement might be removed in the |
346 | to allow per-thread schedulers, but Coro::State does not yet allow |
725 | future to allow per-thread schedulers, but Coro::State does not yet allow |
347 | this). |
726 | this). I recommend disabling thread support and using processes, as having |
|
|
727 | the windows process emulation enabled under unix roughly halves perl |
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728 | performance, even when not used. |
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729 | |
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730 | =item coroutine switching not signal safe |
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731 | |
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732 | You must not switch to another coroutine from within a signal handler |
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733 | (only relevant with %SIG - most event libraries provide safe signals). |
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734 | |
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735 | That means you I<MUST NOT> call any function that might "block" the |
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736 | current coroutine - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or |
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737 | anything that calls those. Everything else, including calling C<ready>, |
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738 | works. |
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739 | |
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740 | =back |
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741 | |
348 | |
742 | |
349 | =head1 SEE ALSO |
743 | =head1 SEE ALSO |
350 | |
744 | |
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745 | Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>. |
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746 | |
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747 | Debugging: L<Coro::Debug>. |
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748 | |
351 | Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>. |
749 | Support/Utility: L<Coro::Specific>, L<Coro::Util>. |
352 | |
750 | |
353 | Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>. |
751 | Locking and IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, |
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752 | L<Coro::SemaphoreSet>, L<Coro::RWLock>. |
354 | |
753 | |
355 | Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>. |
754 | I/O and Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>. |
356 | |
755 | |
357 | Embedding: L<Coro:MakeMaker> |
756 | Compatibility with other modules: L<Coro::LWP> (but see also L<AnyEvent::HTTP> for |
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757 | a better-working alternative), L<Coro::BDB>, L<Coro::Storable>, |
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758 | L<Coro::Select>. |
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759 | |
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760 | XS API: L<Coro::MakeMaker>. |
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761 | |
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762 | Low level Configuration, Thread Environment, Continuations: L<Coro::State>. |
358 | |
763 | |
359 | =head1 AUTHOR |
764 | =head1 AUTHOR |
360 | |
765 | |
361 | Marc Lehmann <schmorp@schmorp.de> |
766 | Marc Lehmann <schmorp@schmorp.de> |
362 | http://home.schmorp.de/ |
767 | http://home.schmorp.de/ |