1 | =head1 NAME |
1 | =head1 NAME |
2 | |
2 | |
3 | Coro - coroutine process abstraction |
3 | Coro - the real perl threads |
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 coroutine 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, that is, cooperative |
24 | threads but don't run in parallel. |
32 | threads. Coroutines are similar to kernel threads but don't (in general) |
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33 | run in parallel at the same time even on SMP machines. The specific flavor |
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34 | of coroutine used in this module also guarantees you that it will not |
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35 | switch between coroutines unless necessary, at easily-identified points |
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36 | in your program, so locking and parallel access are rarely an issue, |
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37 | making coroutine programming much safer and easier than using other thread |
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38 | models. |
25 | |
39 | |
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40 | Unlike the so-called "Perl threads" (which are not actually real threads |
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41 | but only the windows process emulation ported to unix), Coro provides a |
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42 | full shared address space, which makes communication between coroutines |
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43 | very easy. And coroutines are fast, too: disabling the Windows process |
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44 | emulation code in your perl and using Coro can easily result in a two to |
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45 | four times speed increase for your programs. |
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46 | |
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47 | Coro achieves that by supporting multiple running interpreters that share |
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48 | data, which is especially useful to code pseudo-parallel processes and |
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49 | for event-based programming, such as multiple HTTP-GET requests running |
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50 | concurrently. See L<Coro::AnyEvent> to learn more on how to integrate Coro |
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51 | into an event-based environment. |
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52 | |
26 | In this module, coroutines are defined as "callchain + lexical variables |
53 | In this module, a coroutines is defined as "callchain + lexical variables |
27 | + @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own |
54 | + @_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own |
28 | callchain, it's own set of lexicals and it's own set of perl's most |
55 | callchain, its own set of lexicals and its own set of perls most important |
29 | important global variables. |
56 | global variables (see L<Coro::State> for more configuration and background |
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57 | info). |
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58 | |
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59 | See also the C<SEE ALSO> section at the end of this document - the Coro |
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60 | module family is quite large. |
30 | |
61 | |
31 | =cut |
62 | =cut |
32 | |
63 | |
33 | package Coro; |
64 | package Coro; |
34 | |
65 | |
35 | use strict; |
66 | use strict qw(vars subs); |
36 | no warnings "uninitialized"; |
67 | no warnings "uninitialized"; |
37 | |
68 | |
38 | use Coro::State; |
69 | use Coro::State; |
39 | |
70 | |
40 | use base qw(Coro::State Exporter); |
71 | use base qw(Coro::State Exporter); |
41 | |
72 | |
42 | our $idle; # idle handler |
73 | our $idle; # idle handler |
43 | our $main; # main coroutine |
74 | our $main; # main coroutine |
44 | our $current; # current coroutine |
75 | our $current; # current coroutine |
45 | |
76 | |
46 | our $VERSION = '3.01'; |
77 | our $VERSION = "5.0"; |
47 | |
78 | |
48 | our @EXPORT = qw(async cede schedule terminate current unblock_sub); |
79 | our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); |
49 | our %EXPORT_TAGS = ( |
80 | our %EXPORT_TAGS = ( |
50 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
81 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
51 | ); |
82 | ); |
52 | our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready)); |
83 | our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready)); |
53 | |
84 | |
54 | { |
85 | =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 | |
86 | |
88 | =over 4 |
87 | =over 4 |
89 | |
88 | |
90 | =item $main |
89 | =item $Coro::main |
91 | |
90 | |
92 | This coroutine represents the main program. |
91 | This variable stores the coroutine object that represents the main |
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92 | program. While you cna C<ready> it and do most other things you can do to |
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93 | coroutines, it is mainly useful to compare again C<$Coro::current>, to see |
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94 | whether you are running in the main program or not. |
93 | |
95 | |
94 | =cut |
96 | =cut |
95 | |
97 | |
96 | $main = new Coro; |
98 | # $main is now being initialised by Coro::State |
97 | |
99 | |
98 | =item $current (or as function: current) |
100 | =item $Coro::current |
99 | |
101 | |
100 | The current coroutine (the last coroutine switched to). The initial value |
102 | The coroutine object representing the current coroutine (the last |
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103 | coroutine that the Coro scheduler switched to). The initial value is |
101 | is C<$main> (of course). |
104 | C<$Coro::main> (of course). |
102 | |
105 | |
103 | This variable is B<strictly> I<read-only>. It is provided for performance |
106 | This variable is B<strictly> I<read-only>. You can take copies of the |
104 | reasons. If performance is not essentiel you are encouraged to use the |
107 | value stored in it and use it as any other coroutine object, but you must |
105 | C<Coro::current> function instead. |
108 | not otherwise modify the variable itself. |
106 | |
109 | |
107 | =cut |
110 | =cut |
108 | |
111 | |
109 | # maybe some other module used Coro::Specific before... |
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110 | $main->{specific} = $current->{specific} |
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111 | if $current; |
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112 | |
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113 | _set_current $main; |
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114 | |
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115 | sub current() { $current } |
112 | sub current() { $current } # [DEPRECATED] |
116 | |
113 | |
117 | =item $idle |
114 | =item $Coro::idle |
118 | |
115 | |
119 | A callback that is called whenever the scheduler finds no ready coroutines |
116 | This variable is mainly useful to integrate Coro into event loops. It is |
120 | to run. The default implementation prints "FATAL: deadlock detected" and |
117 | usually better to rely on L<Coro::AnyEvent> or LC<Coro::EV>, as this is |
121 | exits, because the program has no other way to continue. |
118 | pretty low-level functionality. |
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119 | |
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120 | This variable stores a callback that is called whenever the scheduler |
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121 | finds no ready coroutines to run. The default implementation prints |
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122 | "FATAL: deadlock detected" and exits, because the program has no other way |
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123 | to continue. |
122 | |
124 | |
123 | This hook is overwritten by modules such as C<Coro::Timer> and |
125 | This hook is overwritten by modules such as C<Coro::Timer> and |
124 | C<Coro::Event> to wait on an external event that hopefully wake up a |
126 | C<Coro::AnyEvent> to wait on an external event that hopefully wake up a |
125 | coroutine so the scheduler can run it. |
127 | coroutine so the scheduler can run it. |
126 | |
128 | |
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129 | Note that the callback I<must not>, under any circumstances, block |
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130 | the current coroutine. Normally, this is achieved by having an "idle |
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131 | coroutine" that calls the event loop and then blocks again, and then |
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132 | readying that coroutine in the idle handler. |
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133 | |
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134 | See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this |
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135 | technique. |
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136 | |
127 | Please note that if your callback recursively invokes perl (e.g. for event |
137 | Please note that if your callback recursively invokes perl (e.g. for event |
128 | handlers), then it must be prepared to be called recursively. |
138 | handlers), then it must be prepared to be called recursively itself. |
129 | |
139 | |
130 | =cut |
140 | =cut |
131 | |
141 | |
132 | $idle = sub { |
142 | $idle = sub { |
133 | require Carp; |
143 | require Carp; |
134 | Carp::croak ("FATAL: deadlock detected"); |
144 | Carp::croak ("FATAL: deadlock detected"); |
135 | }; |
145 | }; |
136 | |
146 | |
137 | # this coroutine is necessary because a coroutine |
147 | # this coroutine is necessary because a coroutine |
138 | # cannot destroy itself. |
148 | # cannot destroy itself. |
139 | my @destroy; |
149 | our @destroy; |
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150 | our $manager; |
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151 | |
140 | my $manager; $manager = new Coro sub { |
152 | $manager = new Coro sub { |
141 | while () { |
153 | while () { |
142 | # by overwriting the state object with the manager we destroy it |
154 | Coro::_cancel shift @destroy |
143 | # while still being able to schedule this coroutine (in case it has |
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144 | # been readied multiple times. this is harmless since the manager |
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145 | # can be called as many times as neccessary and will always |
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146 | # remove itself from the runqueue |
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147 | while (@destroy) { |
155 | while @destroy; |
148 | my $coro = pop @destroy; |
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149 | $coro->{status} ||= []; |
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150 | $_->ready for @{delete $coro->{join} || []}; |
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151 | |
156 | |
152 | # the next line destroys the coro state, but keeps the |
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153 | # coroutine itself intact (we basically make it a zombie |
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154 | # coroutine that always runs the manager thread, so it's possible |
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155 | # to transfer() to this coroutine). |
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156 | $coro->_clone_state_from ($manager); |
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157 | } |
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158 | &schedule; |
157 | &schedule; |
159 | } |
158 | } |
160 | }; |
159 | }; |
161 | |
160 | $manager->{desc} = "[coro manager]"; |
162 | # static methods. not really. |
161 | $manager->prio (PRIO_MAX); |
163 | |
162 | |
164 | =back |
163 | =back |
165 | |
164 | |
166 | =head2 STATIC METHODS |
165 | =head1 SIMPLE COROUTINE CREATION |
167 | |
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168 | Static methods are actually functions that operate on the current coroutine only. |
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169 | |
166 | |
170 | =over 4 |
167 | =over 4 |
171 | |
168 | |
172 | =item async { ... } [@args...] |
169 | =item async { ... } [@args...] |
173 | |
170 | |
174 | Create a new asynchronous coroutine and return it's coroutine object |
171 | Create a new coroutine and return it's coroutine object (usually |
175 | (usually unused). When the sub returns the new coroutine is automatically |
172 | unused). The coroutine will be put into the ready queue, so |
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173 | it will start running automatically on the next scheduler run. |
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174 | |
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175 | The first argument is a codeblock/closure that should be executed in the |
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176 | coroutine. When it returns argument returns the coroutine is automatically |
176 | terminated. |
177 | terminated. |
177 | |
178 | |
178 | Calling C<exit> in a coroutine will not work correctly, so do not do that. |
179 | The remaining arguments are passed as arguments to the closure. |
179 | |
180 | |
180 | When the coroutine dies, the program will exit, just as in the main |
181 | See the C<Coro::State::new> constructor for info about the coroutine |
181 | program. |
182 | environment in which coroutines are executed. |
182 | |
183 | |
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184 | Calling C<exit> in a coroutine will do the same as calling exit outside |
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185 | the coroutine. Likewise, when the coroutine dies, the program will exit, |
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186 | just as it would in the main program. |
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187 | |
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188 | If you do not want that, you can provide a default C<die> handler, or |
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189 | simply avoid dieing (by use of C<eval>). |
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190 | |
183 | # create a new coroutine that just prints its arguments |
191 | Example: Create a new coroutine that just prints its arguments. |
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192 | |
184 | async { |
193 | async { |
185 | print "@_\n"; |
194 | print "@_\n"; |
186 | } 1,2,3,4; |
195 | } 1,2,3,4; |
187 | |
196 | |
188 | =cut |
197 | =cut |
189 | |
198 | |
190 | sub async(&@) { |
199 | sub async(&@) { |
191 | my $pid = new Coro @_; |
200 | my $coro = new Coro @_; |
192 | $pid->ready; |
201 | $coro->ready; |
193 | $pid |
202 | $coro |
194 | } |
203 | } |
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204 | |
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205 | =item async_pool { ... } [@args...] |
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206 | |
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207 | Similar to C<async>, but uses a coroutine pool, so you should not call |
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208 | terminate or join on it (although you are allowed to), and you get a |
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209 | coroutine that might have executed other code already (which can be good |
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210 | or bad :). |
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211 | |
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212 | On the plus side, this function is about twice as fast as creating (and |
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213 | destroying) a completely new coroutine, so if you need a lot of generic |
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214 | coroutines in quick successsion, use C<async_pool>, not C<async>. |
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215 | |
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216 | The code block is executed in an C<eval> context and a warning will be |
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217 | issued in case of an exception instead of terminating the program, as |
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218 | C<async> does. As the coroutine is being reused, stuff like C<on_destroy> |
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219 | will not work in the expected way, unless you call terminate or cancel, |
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220 | which somehow defeats the purpose of pooling (but is fine in the |
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221 | exceptional case). |
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222 | |
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223 | The priority will be reset to C<0> after each run, tracing will be |
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224 | disabled, the description will be reset and the default output filehandle |
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225 | gets restored, so you can change all these. Otherwise the coroutine will |
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226 | be re-used "as-is": most notably if you change other per-coroutine global |
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227 | stuff such as C<$/> you I<must needs> revert that change, which is most |
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228 | simply done by using local as in: C<< local $/ >>. |
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229 | |
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230 | The idle pool size is limited to C<8> idle coroutines (this can be |
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231 | adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle |
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232 | coros as required. |
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233 | |
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234 | If you are concerned about pooled coroutines growing a lot because a |
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235 | single C<async_pool> used a lot of stackspace you can e.g. C<async_pool |
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236 | { terminate }> once per second or so to slowly replenish the pool. In |
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237 | addition to that, when the stacks used by a handler grows larger than 32kb |
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238 | (adjustable via $Coro::POOL_RSS) it will also be destroyed. |
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239 | |
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240 | =cut |
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241 | |
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242 | our $POOL_SIZE = 8; |
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243 | our $POOL_RSS = 32 * 1024; |
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244 | our @async_pool; |
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245 | |
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246 | sub pool_handler { |
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247 | while () { |
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248 | eval { |
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249 | &{&_pool_handler} while 1; |
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250 | }; |
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251 | |
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252 | warn $@ if $@; |
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253 | } |
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254 | } |
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255 | |
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256 | =back |
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257 | |
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258 | =head1 STATIC METHODS |
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259 | |
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260 | Static methods are actually functions that implicitly operate on the |
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261 | current coroutine. |
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262 | |
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263 | =over 4 |
195 | |
264 | |
196 | =item schedule |
265 | =item schedule |
197 | |
266 | |
198 | Calls the scheduler. Please note that the current coroutine will not be put |
267 | Calls the scheduler. The scheduler will find the next coroutine that is |
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268 | to be run from the ready queue and switches to it. The next coroutine |
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269 | to be run is simply the one with the highest priority that is longest |
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270 | in its ready queue. If there is no coroutine ready, it will clal the |
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271 | C<$Coro::idle> hook. |
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272 | |
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273 | Please note that the current coroutine will I<not> be put into the ready |
199 | into the ready queue, so calling this function usually means you will |
274 | queue, so calling this function usually means you will never be called |
200 | never be called again unless something else (e.g. an event handler) calls |
275 | again unless something else (e.g. an event handler) calls C<< ->ready >>, |
201 | ready. |
276 | thus waking you up. |
202 | |
277 | |
203 | The canonical way to wait on external events is this: |
278 | This makes C<schedule> I<the> generic method to use to block the current |
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279 | coroutine and wait for events: first you remember the current coroutine in |
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280 | a variable, then arrange for some callback of yours to call C<< ->ready |
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281 | >> on that once some event happens, and last you call C<schedule> to put |
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282 | yourself to sleep. Note that a lot of things can wake your coroutine up, |
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283 | so you need to check whether the event indeed happened, e.g. by storing the |
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284 | status in a variable. |
204 | |
285 | |
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286 | See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks. |
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287 | |
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288 | =item cede |
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289 | |
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290 | "Cede" to other coroutines. This function puts the current coroutine into |
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291 | the ready queue and calls C<schedule>, which has the effect of giving |
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292 | up the current "timeslice" to other coroutines of the same or higher |
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293 | priority. Once your coroutine gets its turn again it will automatically be |
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294 | resumed. |
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295 | |
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296 | This function is often called C<yield> in other languages. |
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297 | |
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298 | =item Coro::cede_notself |
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299 | |
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300 | Works like cede, but is not exported by default and will cede to I<any> |
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301 | coroutine, regardless of priority. This is useful sometimes to ensure |
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302 | progress is made. |
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303 | |
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304 | =item terminate [arg...] |
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305 | |
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306 | Terminates the current coroutine with the given status values (see L<cancel>). |
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307 | |
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308 | =item killall |
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309 | |
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310 | Kills/terminates/cancels all coroutines except the currently running |
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311 | one. This is useful after a fork, either in the child or the parent, as |
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312 | usually only one of them should inherit the running coroutines. |
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313 | |
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314 | Note that while this will try to free some of the main programs resources, |
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315 | you cannot free all of them, so if a coroutine that is not the main |
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316 | program calls this function, there will be some one-time resource leak. |
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317 | |
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318 | =cut |
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319 | |
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320 | sub killall { |
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321 | for (Coro::State::list) { |
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322 | $_->cancel |
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323 | if $_ != $current && UNIVERSAL::isa $_, "Coro"; |
205 | { |
324 | } |
206 | # remember current coroutine |
325 | } |
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326 | |
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327 | =back |
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328 | |
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329 | =head1 COROUTINE OBJECT METHODS |
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330 | |
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331 | These are the methods you can call on coroutine objects (or to create |
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332 | them). |
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333 | |
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334 | =over 4 |
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335 | |
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336 | =item new Coro \&sub [, @args...] |
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337 | |
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338 | Create a new coroutine and return it. When the sub returns, the coroutine |
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339 | automatically terminates as if C<terminate> with the returned values were |
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340 | called. To make the coroutine run you must first put it into the ready |
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341 | queue by calling the ready method. |
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342 | |
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343 | See C<async> and C<Coro::State::new> for additional info about the |
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344 | coroutine environment. |
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345 | |
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346 | =cut |
|
|
347 | |
|
|
348 | sub _terminate { |
|
|
349 | terminate &{+shift}; |
|
|
350 | } |
|
|
351 | |
|
|
352 | =item $success = $coroutine->ready |
|
|
353 | |
|
|
354 | Put the given coroutine into the end of its ready queue (there is one |
|
|
355 | queue for each priority) and return true. If the coroutine is already in |
|
|
356 | the ready queue, do nothing and return false. |
|
|
357 | |
|
|
358 | This ensures that the scheduler will resume this coroutine automatically |
|
|
359 | once all the coroutines of higher priority and all coroutines of the same |
|
|
360 | priority that were put into the ready queue earlier have been resumed. |
|
|
361 | |
|
|
362 | =item $is_ready = $coroutine->is_ready |
|
|
363 | |
|
|
364 | Return whether the coroutine is currently the ready queue or not, |
|
|
365 | |
|
|
366 | =item $coroutine->cancel (arg...) |
|
|
367 | |
|
|
368 | Terminates the given coroutine and makes it return the given arguments as |
|
|
369 | status (default: the empty list). Never returns if the coroutine is the |
|
|
370 | current coroutine. |
|
|
371 | |
|
|
372 | =cut |
|
|
373 | |
|
|
374 | sub cancel { |
|
|
375 | my $self = shift; |
|
|
376 | |
|
|
377 | if ($current == $self) { |
|
|
378 | terminate @_; |
|
|
379 | } else { |
|
|
380 | $self->{_status} = [@_]; |
|
|
381 | $self->_cancel; |
|
|
382 | } |
|
|
383 | } |
|
|
384 | |
|
|
385 | =item $coroutine->schedule_to |
|
|
386 | |
|
|
387 | Puts the current coroutine to sleep (like C<Coro::schedule>), but instead |
|
|
388 | of continuing with the next coro from the ready queue, always switch to |
|
|
389 | the given coroutine object (regardless of priority etc.). The readyness |
|
|
390 | state of that coroutine isn't changed. |
|
|
391 | |
|
|
392 | This is an advanced method for special cases - I'd love to hear about any |
|
|
393 | uses for this one. |
|
|
394 | |
|
|
395 | =item $coroutine->cede_to |
|
|
396 | |
|
|
397 | Like C<schedule_to>, but puts the current coroutine into the ready |
|
|
398 | queue. This has the effect of temporarily switching to the given |
|
|
399 | coroutine, and continuing some time later. |
|
|
400 | |
|
|
401 | This is an advanced method for special cases - I'd love to hear about any |
|
|
402 | uses for this one. |
|
|
403 | |
|
|
404 | =item $coroutine->throw ([$scalar]) |
|
|
405 | |
|
|
406 | If C<$throw> is specified and defined, it will be thrown as an exception |
|
|
407 | inside the coroutine at the next convenient point in time. Otherwise |
|
|
408 | clears the exception object. |
|
|
409 | |
|
|
410 | Coro will check for the exception each time a schedule-like-function |
|
|
411 | returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down |
|
|
412 | >>, C<< Coro::Handle->readable >> and so on. Most of these functions |
|
|
413 | detect this case and return early in case an exception is pending. |
|
|
414 | |
|
|
415 | The exception object will be thrown "as is" with the specified scalar in |
|
|
416 | C<$@>, i.e. if it is a string, no line number or newline will be appended |
|
|
417 | (unlike with C<die>). |
|
|
418 | |
|
|
419 | This can be used as a softer means than C<cancel> to ask a coroutine to |
|
|
420 | end itself, although there is no guarantee that the exception will lead to |
|
|
421 | termination, and if the exception isn't caught it might well end the whole |
|
|
422 | program. |
|
|
423 | |
|
|
424 | You might also think of C<throw> as being the moral equivalent of |
|
|
425 | C<kill>ing a coroutine with a signal (in this case, a scalar). |
|
|
426 | |
|
|
427 | =item $coroutine->join |
|
|
428 | |
|
|
429 | Wait until the coroutine terminates and return any values given to the |
|
|
430 | C<terminate> or C<cancel> functions. C<join> can be called concurrently |
|
|
431 | from multiple coroutines, and all will be resumed and given the status |
|
|
432 | return once the C<$coroutine> terminates. |
|
|
433 | |
|
|
434 | =cut |
|
|
435 | |
|
|
436 | sub join { |
|
|
437 | my $self = shift; |
|
|
438 | |
|
|
439 | unless ($self->{_status}) { |
207 | my $current = $Coro::current; |
440 | my $current = $current; |
208 | |
441 | |
209 | # register a hypothetical event handler |
442 | push @{$self->{_on_destroy}}, sub { |
210 | on_event_invoke sub { |
|
|
211 | # wake up sleeping coroutine |
|
|
212 | $current->ready; |
443 | $current->ready; |
213 | undef $current; |
444 | undef $current; |
214 | }; |
445 | }; |
215 | |
446 | |
216 | # call schedule until event occured. |
|
|
217 | # in case we are woken up for other reasons |
|
|
218 | # (current still defined), loop. |
|
|
219 | Coro::schedule while $current; |
447 | &schedule while $current; |
220 | } |
448 | } |
221 | |
449 | |
222 | =item cede |
|
|
223 | |
|
|
224 | "Cede" to other coroutines. This function puts the current coroutine into the |
|
|
225 | ready queue and calls C<schedule>, which has the effect of giving up the |
|
|
226 | current "timeslice" to other coroutines of the same or higher priority. |
|
|
227 | |
|
|
228 | =item terminate [arg...] |
|
|
229 | |
|
|
230 | Terminates the current coroutine with the given status values (see L<cancel>). |
|
|
231 | |
|
|
232 | =cut |
|
|
233 | |
|
|
234 | sub terminate { |
|
|
235 | $current->cancel (@_); |
|
|
236 | } |
|
|
237 | |
|
|
238 | =back |
|
|
239 | |
|
|
240 | # dynamic methods |
|
|
241 | |
|
|
242 | =head2 COROUTINE METHODS |
|
|
243 | |
|
|
244 | These are the methods you can call on coroutine objects. |
|
|
245 | |
|
|
246 | =over 4 |
|
|
247 | |
|
|
248 | =item new Coro \&sub [, @args...] |
|
|
249 | |
|
|
250 | Create a new coroutine and return it. When the sub returns the coroutine |
|
|
251 | automatically terminates as if C<terminate> with the returned values were |
|
|
252 | called. To make the coroutine run you must first put it into the ready queue |
|
|
253 | by calling the ready method. |
|
|
254 | |
|
|
255 | Calling C<exit> in a coroutine will not work correctly, so do not do that. |
|
|
256 | |
|
|
257 | =cut |
|
|
258 | |
|
|
259 | sub _run_coro { |
|
|
260 | terminate &{+shift}; |
|
|
261 | } |
|
|
262 | |
|
|
263 | sub new { |
|
|
264 | my $class = shift; |
|
|
265 | |
|
|
266 | $class->SUPER::new (\&_run_coro, @_) |
|
|
267 | } |
|
|
268 | |
|
|
269 | =item $success = $coroutine->ready |
|
|
270 | |
|
|
271 | Put the given coroutine into the ready queue (according to it's priority) |
|
|
272 | and return true. If the coroutine is already in the ready queue, do nothing |
|
|
273 | and return false. |
|
|
274 | |
|
|
275 | =item $is_ready = $coroutine->is_ready |
|
|
276 | |
|
|
277 | Return wether the coroutine is currently the ready queue or not, |
|
|
278 | |
|
|
279 | =item $coroutine->cancel (arg...) |
|
|
280 | |
|
|
281 | Terminates the given coroutine and makes it return the given arguments as |
|
|
282 | status (default: the empty list). |
|
|
283 | |
|
|
284 | =cut |
|
|
285 | |
|
|
286 | sub cancel { |
|
|
287 | my $self = shift; |
|
|
288 | $self->{status} = [@_]; |
|
|
289 | push @destroy, $self; |
|
|
290 | $manager->ready; |
|
|
291 | &schedule if $current == $self; |
|
|
292 | } |
|
|
293 | |
|
|
294 | =item $coroutine->join |
|
|
295 | |
|
|
296 | Wait until the coroutine terminates and return any values given to the |
|
|
297 | C<terminate> or C<cancel> functions. C<join> can be called multiple times |
|
|
298 | from multiple coroutine. |
|
|
299 | |
|
|
300 | =cut |
|
|
301 | |
|
|
302 | sub join { |
|
|
303 | my $self = shift; |
|
|
304 | unless ($self->{status}) { |
|
|
305 | push @{$self->{join}}, $current; |
|
|
306 | &schedule; |
|
|
307 | } |
|
|
308 | wantarray ? @{$self->{status}} : $self->{status}[0]; |
450 | wantarray ? @{$self->{_status}} : $self->{_status}[0]; |
|
|
451 | } |
|
|
452 | |
|
|
453 | =item $coroutine->on_destroy (\&cb) |
|
|
454 | |
|
|
455 | Registers a callback that is called when this coroutine gets destroyed, |
|
|
456 | but before it is joined. The callback gets passed the terminate arguments, |
|
|
457 | if any, and I<must not> die, under any circumstances. |
|
|
458 | |
|
|
459 | =cut |
|
|
460 | |
|
|
461 | sub on_destroy { |
|
|
462 | my ($self, $cb) = @_; |
|
|
463 | |
|
|
464 | push @{ $self->{_on_destroy} }, $cb; |
309 | } |
465 | } |
310 | |
466 | |
311 | =item $oldprio = $coroutine->prio ($newprio) |
467 | =item $oldprio = $coroutine->prio ($newprio) |
312 | |
468 | |
313 | Sets (or gets, if the argument is missing) the priority of the |
469 | Sets (or gets, if the argument is missing) the priority of the |
… | |
… | |
336 | higher values mean lower priority, just as in unix). |
492 | higher values mean lower priority, just as in unix). |
337 | |
493 | |
338 | =item $olddesc = $coroutine->desc ($newdesc) |
494 | =item $olddesc = $coroutine->desc ($newdesc) |
339 | |
495 | |
340 | Sets (or gets in case the argument is missing) the description for this |
496 | Sets (or gets in case the argument is missing) the description for this |
341 | coroutine. This is just a free-form string you can associate with a coroutine. |
497 | coroutine. This is just a free-form string you can associate with a |
|
|
498 | coroutine. |
|
|
499 | |
|
|
500 | This method simply sets the C<< $coroutine->{desc} >> member to the given |
|
|
501 | string. You can modify this member directly if you wish. |
342 | |
502 | |
343 | =cut |
503 | =cut |
344 | |
504 | |
345 | sub desc { |
505 | sub desc { |
346 | my $old = $_[0]{desc}; |
506 | my $old = $_[0]{desc}; |
347 | $_[0]{desc} = $_[1] if @_ > 1; |
507 | $_[0]{desc} = $_[1] if @_ > 1; |
348 | $old; |
508 | $old; |
349 | } |
509 | } |
350 | |
510 | |
|
|
511 | sub transfer { |
|
|
512 | require Carp; |
|
|
513 | Carp::croak ("You must not call ->transfer on Coro objects. Use Coro::State objects or the ->schedule_to method. Caught"); |
|
|
514 | } |
|
|
515 | |
351 | =back |
516 | =back |
352 | |
517 | |
353 | =head2 GLOBAL FUNCTIONS |
518 | =head1 GLOBAL FUNCTIONS |
354 | |
519 | |
355 | =over 4 |
520 | =over 4 |
356 | |
521 | |
357 | =item Coro::nready |
522 | =item Coro::nready |
358 | |
523 | |
359 | Returns the number of coroutines that are currently in the ready state, |
524 | Returns the number of coroutines that are currently in the ready state, |
360 | i.e. that can be swicthed to. The value C<0> means that the only runnable |
525 | i.e. that can be switched to by calling C<schedule> directory or |
|
|
526 | indirectly. The value C<0> means that the only runnable coroutine is the |
361 | coroutine is the currently running one, so C<cede> would have no effect, |
527 | currently running one, so C<cede> would have no effect, and C<schedule> |
362 | and C<schedule> would cause a deadlock unless there is an idle handler |
528 | would cause a deadlock unless there is an idle handler that wakes up some |
363 | that wakes up some coroutines. |
529 | coroutines. |
|
|
530 | |
|
|
531 | =item my $guard = Coro::guard { ... } |
|
|
532 | |
|
|
533 | This creates and returns a guard object. Nothing happens until the object |
|
|
534 | gets destroyed, in which case the codeblock given as argument will be |
|
|
535 | executed. This is useful to free locks or other resources in case of a |
|
|
536 | runtime error or when the coroutine gets canceled, as in both cases the |
|
|
537 | guard block will be executed. The guard object supports only one method, |
|
|
538 | C<< ->cancel >>, which will keep the codeblock from being executed. |
|
|
539 | |
|
|
540 | Example: set some flag and clear it again when the coroutine gets canceled |
|
|
541 | or the function returns: |
|
|
542 | |
|
|
543 | sub do_something { |
|
|
544 | my $guard = Coro::guard { $busy = 0 }; |
|
|
545 | $busy = 1; |
|
|
546 | |
|
|
547 | # do something that requires $busy to be true |
|
|
548 | } |
|
|
549 | |
|
|
550 | =cut |
|
|
551 | |
|
|
552 | sub guard(&) { |
|
|
553 | bless \(my $cb = $_[0]), "Coro::guard" |
|
|
554 | } |
|
|
555 | |
|
|
556 | sub Coro::guard::cancel { |
|
|
557 | ${$_[0]} = sub { }; |
|
|
558 | } |
|
|
559 | |
|
|
560 | sub Coro::guard::DESTROY { |
|
|
561 | ${$_[0]}->(); |
|
|
562 | } |
|
|
563 | |
364 | |
564 | |
365 | =item unblock_sub { ... } |
565 | =item unblock_sub { ... } |
366 | |
566 | |
367 | This utility function takes a BLOCK or code reference and "unblocks" it, |
567 | This utility function takes a BLOCK or code reference and "unblocks" it, |
368 | returning the new coderef. This means that the new coderef will return |
568 | returning a new coderef. Unblocking means that calling the new coderef |
369 | immediately without blocking, returning nothing, while the original code |
569 | will return immediately without blocking, returning nothing, while the |
370 | ref will be called (with parameters) from within its own coroutine. |
570 | original code ref will be called (with parameters) from within another |
|
|
571 | coroutine. |
371 | |
572 | |
372 | The reason this fucntion exists is that many event libraries (such as the |
573 | The reason this function exists is that many event libraries (such as the |
373 | venerable L<Event|Event> module) are not coroutine-safe (a weaker form |
574 | venerable L<Event|Event> module) are not coroutine-safe (a weaker form |
374 | of thread-safety). This means you must not block within event callbacks, |
575 | of thread-safety). This means you must not block within event callbacks, |
375 | otherwise you might suffer from crashes or worse. |
576 | otherwise you might suffer from crashes or worse. The only event library |
|
|
577 | currently known that is safe to use without C<unblock_sub> is L<EV>. |
376 | |
578 | |
377 | This function allows your callbacks to block by executing them in another |
579 | This function allows your callbacks to block by executing them in another |
378 | coroutine where it is safe to block. One example where blocking is handy |
580 | coroutine where it is safe to block. One example where blocking is handy |
379 | is when you use the L<Coro::AIO|Coro::AIO> functions to save results to |
581 | is when you use the L<Coro::AIO|Coro::AIO> functions to save results to |
380 | disk. |
582 | disk, for example. |
381 | |
583 | |
382 | In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when |
584 | In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when |
383 | creating event callbacks that want to block. |
585 | creating event callbacks that want to block. |
384 | |
586 | |
385 | =cut |
587 | If your handler does not plan to block (e.g. simply sends a message to |
|
|
588 | another coroutine, or puts some other coroutine into the ready queue), |
|
|
589 | there is no reason to use C<unblock_sub>. |
386 | |
590 | |
387 | our @unblock_pool; |
591 | Note that you also need to use C<unblock_sub> for any other callbacks that |
|
|
592 | are indirectly executed by any C-based event loop. For example, when you |
|
|
593 | use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it |
|
|
594 | provides callbacks that are the result of some event callback, then you |
|
|
595 | must not block either, or use C<unblock_sub>. |
|
|
596 | |
|
|
597 | =cut |
|
|
598 | |
388 | our @unblock_queue; |
599 | our @unblock_queue; |
389 | our $UNBLOCK_POOL_SIZE = 2; |
|
|
390 | |
600 | |
391 | sub unblock_handler_ { |
601 | # we create a special coro because we want to cede, |
392 | while () { |
602 | # to reduce pressure on the coro pool (because most callbacks |
393 | my ($cb, @arg) = @{ delete $Coro::current->{arg} }; |
603 | # return immediately and can be reused) and because we cannot cede |
394 | $cb->(@arg); |
604 | # inside an event callback. |
395 | |
|
|
396 | last if @unblock_pool >= $UNBLOCK_POOL_SIZE; |
|
|
397 | push @unblock_pool, $Coro::current; |
|
|
398 | schedule; |
|
|
399 | } |
|
|
400 | } |
|
|
401 | |
|
|
402 | our $unblock_scheduler = async { |
605 | our $unblock_scheduler = new Coro sub { |
403 | while () { |
606 | while () { |
404 | while (my $cb = pop @unblock_queue) { |
607 | while (my $cb = pop @unblock_queue) { |
405 | my $handler = (pop @unblock_pool or new Coro \&unblock_handler_); |
608 | &async_pool (@$cb); |
406 | $handler->{arg} = $cb; |
609 | |
407 | $handler->ready; |
610 | # for short-lived callbacks, this reduces pressure on the coro pool |
|
|
611 | # as the chance is very high that the async_poll coro will be back |
|
|
612 | # in the idle state when cede returns |
408 | cede; |
613 | cede; |
409 | } |
614 | } |
410 | |
615 | schedule; # sleep well |
411 | schedule; |
|
|
412 | } |
616 | } |
413 | }; |
617 | }; |
|
|
618 | $unblock_scheduler->{desc} = "[unblock_sub scheduler]"; |
414 | |
619 | |
415 | sub unblock_sub(&) { |
620 | sub unblock_sub(&) { |
416 | my $cb = shift; |
621 | my $cb = shift; |
417 | |
622 | |
418 | sub { |
623 | sub { |
419 | push @unblock_queue, [$cb, @_]; |
624 | unshift @unblock_queue, [$cb, @_]; |
420 | $unblock_scheduler->ready; |
625 | $unblock_scheduler->ready; |
421 | } |
626 | } |
422 | } |
627 | } |
423 | |
628 | |
|
|
629 | =item $cb = Coro::rouse_cb |
|
|
630 | |
|
|
631 | Create and return a "rouse callback". That's a code reference that, when |
|
|
632 | called, will save its arguments and notify the owner coroutine of the |
|
|
633 | callback. |
|
|
634 | |
|
|
635 | See the next function. |
|
|
636 | |
|
|
637 | =item @args = Coro::rouse_wait [$cb] |
|
|
638 | |
|
|
639 | Wait for the specified rouse callback (or the last one tht was created in |
|
|
640 | this coroutine). |
|
|
641 | |
|
|
642 | As soon as the callback is invoked (or when the calback was invoked before |
|
|
643 | C<rouse_wait>), it will return a copy of the arguments originally passed |
|
|
644 | to the rouse callback. |
|
|
645 | |
|
|
646 | See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example. |
|
|
647 | |
424 | =back |
648 | =back |
425 | |
649 | |
426 | =cut |
650 | =cut |
427 | |
651 | |
428 | 1; |
652 | 1; |
429 | |
653 | |
|
|
654 | =head1 HOW TO WAIT FOR A CALLBACK |
|
|
655 | |
|
|
656 | It is very common for a coroutine to wait for some callback to be |
|
|
657 | called. This occurs naturally when you use coroutines in an otherwise |
|
|
658 | event-based program, or when you use event-based libraries. |
|
|
659 | |
|
|
660 | These typically register a callback for some event, and call that callback |
|
|
661 | when the event occured. In a coroutine, however, you typically want to |
|
|
662 | just wait for the event, simplyifying things. |
|
|
663 | |
|
|
664 | For example C<< AnyEvent->child >> registers a callback to be called when |
|
|
665 | a specific child has exited: |
|
|
666 | |
|
|
667 | my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... }); |
|
|
668 | |
|
|
669 | But from withina coroutine, you often just want to write this: |
|
|
670 | |
|
|
671 | my $status = wait_for_child $pid; |
|
|
672 | |
|
|
673 | Coro offers two functions specifically designed to make this easy, |
|
|
674 | C<Coro::rouse_cb> and C<Coro::rouse_wait>. |
|
|
675 | |
|
|
676 | The first function, C<rouse_cb>, generates and returns a callback that, |
|
|
677 | when invoked, will save it's arguments and notify the coroutine that |
|
|
678 | created the callback. |
|
|
679 | |
|
|
680 | The second function, C<rouse_wait>, waits for the callback to be called |
|
|
681 | (by calling C<schedule> to go to sleep) and returns the arguments |
|
|
682 | originally passed to the callback. |
|
|
683 | |
|
|
684 | Using these functions, it becomes easy to write the C<wait_for_child> |
|
|
685 | function mentioned above: |
|
|
686 | |
|
|
687 | sub wait_for_child($) { |
|
|
688 | my ($pid) = @_; |
|
|
689 | |
|
|
690 | my $watcher = AnyEvent->child (pid => $pid, cb => Coro::rouse_cb); |
|
|
691 | |
|
|
692 | my ($rpid, $rstatus) = Coro::rouse_wait; |
|
|
693 | $rstatus |
|
|
694 | } |
|
|
695 | |
|
|
696 | In the case where C<rouse_cb> and C<rouse_wait> are not flexible enough, |
|
|
697 | you can roll your own, using C<schedule>: |
|
|
698 | |
|
|
699 | sub wait_for_child($) { |
|
|
700 | my ($pid) = @_; |
|
|
701 | |
|
|
702 | # store the current coroutine in $current, |
|
|
703 | # and provide result variables for the closure passed to ->child |
|
|
704 | my $current = $Coro::current; |
|
|
705 | my ($done, $rstatus); |
|
|
706 | |
|
|
707 | # pass a closure to ->child |
|
|
708 | my $watcher = AnyEvent->child (pid => $pid, cb => sub { |
|
|
709 | $rstatus = $_[1]; # remember rstatus |
|
|
710 | $done = 1; # mark $rstatus as valud |
|
|
711 | }); |
|
|
712 | |
|
|
713 | # wait until the closure has been called |
|
|
714 | schedule while !$done; |
|
|
715 | |
|
|
716 | $rstatus |
|
|
717 | } |
|
|
718 | |
|
|
719 | |
430 | =head1 BUGS/LIMITATIONS |
720 | =head1 BUGS/LIMITATIONS |
431 | |
721 | |
432 | - you must make very sure that no coro is still active on global |
722 | =over 4 |
433 | destruction. very bad things might happen otherwise (usually segfaults). |
|
|
434 | |
723 | |
|
|
724 | =item fork with pthread backend |
|
|
725 | |
|
|
726 | When Coro is compiled using the pthread backend (which isn't recommended |
|
|
727 | but required on many BSDs as their libcs are completely broken), then |
|
|
728 | coroutines will not survive a fork. There is no known workaround except to |
|
|
729 | fix your libc and use a saner backend. |
|
|
730 | |
|
|
731 | =item perl process emulation ("threads") |
|
|
732 | |
435 | - this module is not thread-safe. You should only ever use this module |
733 | This module is not perl-pseudo-thread-safe. You should only ever use this |
436 | from the same thread (this requirement might be losened in the future |
734 | module from the same thread (this requirement might be removed in the |
437 | to allow per-thread schedulers, but Coro::State does not yet allow |
735 | future to allow per-thread schedulers, but Coro::State does not yet allow |
438 | this). |
736 | this). I recommend disabling thread support and using processes, as having |
|
|
737 | the windows process emulation enabled under unix roughly halves perl |
|
|
738 | performance, even when not used. |
|
|
739 | |
|
|
740 | =item coroutine switching not signal safe |
|
|
741 | |
|
|
742 | You must not switch to another coroutine from within a signal handler |
|
|
743 | (only relevant with %SIG - most event libraries provide safe signals). |
|
|
744 | |
|
|
745 | That means you I<MUST NOT> call any function that might "block" the |
|
|
746 | current coroutine - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or |
|
|
747 | anything that calls those. Everything else, including calling C<ready>, |
|
|
748 | works. |
|
|
749 | |
|
|
750 | =back |
|
|
751 | |
439 | |
752 | |
440 | =head1 SEE ALSO |
753 | =head1 SEE ALSO |
441 | |
754 | |
|
|
755 | Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>. |
|
|
756 | |
|
|
757 | Debugging: L<Coro::Debug>. |
|
|
758 | |
442 | Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>. |
759 | Support/Utility: L<Coro::Specific>, L<Coro::Util>. |
443 | |
760 | |
444 | Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>. |
761 | Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, |
|
|
762 | L<Coro::SemaphoreSet>, L<Coro::RWLock>. |
445 | |
763 | |
446 | Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>. |
764 | IO/Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>. |
447 | |
765 | |
448 | Embedding: L<Coro:MakeMaker> |
766 | Compatibility: L<Coro::LWP> (but see also L<AnyEvent::HTTP> for |
|
|
767 | a better-working alternative), L<Coro::BDB>, L<Coro::Storable>, |
|
|
768 | L<Coro::Select>. |
|
|
769 | |
|
|
770 | XS API: L<Coro::MakeMaker>. |
|
|
771 | |
|
|
772 | Low level Configuration, Coroutine Environment: L<Coro::State>. |
449 | |
773 | |
450 | =head1 AUTHOR |
774 | =head1 AUTHOR |
451 | |
775 | |
452 | Marc Lehmann <schmorp@schmorp.de> |
776 | Marc Lehmann <schmorp@schmorp.de> |
453 | http://home.schmorp.de/ |
777 | http://home.schmorp.de/ |