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3 | Coro - coroutine process abstraction |
3 | Coro - coroutine process abstraction |
4 | |
4 | |
5 | =head1 SYNOPSIS |
5 | =head1 SYNOPSIS |
6 | |
6 | |
7 | use Coro; |
7 | use Coro; |
8 | |
8 | |
9 | async { |
9 | async { |
10 | # some asynchronous thread of execution |
10 | # some asynchronous thread of execution |
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11 | print "2\n"; |
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12 | cede; # yield back to main |
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13 | print "4\n"; |
11 | }; |
14 | }; |
12 | |
15 | print "1\n"; |
13 | # alternatively create an async process like this: |
16 | cede; # yield to coroutine |
14 | |
17 | print "3\n"; |
15 | sub some_func : Coro { |
18 | cede; # and again |
16 | # some more async code |
19 | |
17 | } |
20 | # use locking |
18 | |
21 | use Coro::Semaphore; |
19 | cede; |
22 | my $lock = new Coro::Semaphore; |
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23 | my $locked; |
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24 | |
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25 | $lock->down; |
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26 | $locked = 1; |
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27 | $lock->up; |
20 | |
28 | |
21 | =head1 DESCRIPTION |
29 | =head1 DESCRIPTION |
22 | |
30 | |
23 | This module collection manages coroutines. Coroutines are similar to |
31 | This module collection manages coroutines. Coroutines are similar to |
24 | threads but don't run in parallel. |
32 | threads but don't (in general) run in parallel at the same time even |
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33 | on SMP machines. The specific flavor of coroutine used in this module |
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34 | also guarantees you that it will not switch between coroutines unless |
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35 | necessary, at easily-identified points in your program, so locking and |
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36 | parallel access are rarely an issue, making coroutine programming much |
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37 | safer and easier than threads programming. |
25 | |
38 | |
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39 | Unlike a normal perl program, however, coroutines allow you to have |
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40 | multiple running interpreters that share data, which is especially useful |
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41 | to code pseudo-parallel processes and for event-based programming, such as |
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42 | multiple HTTP-GET requests running concurrently. See L<Coro::AnyEvent> to |
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43 | learn more. |
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44 | |
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45 | Coroutines are also useful because Perl has no support for threads (the so |
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46 | called "threads" that perl offers are nothing more than the (bad) process |
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47 | emulation coming from the Windows platform: On standard operating systems |
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48 | they serve no purpose whatsoever, except by making your programs slow and |
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49 | making them use a lot of memory. Best disable them when building perl, or |
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50 | aks your software vendor/distributor to do it for you). |
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51 | |
26 | In this module, coroutines are defined as "callchain + lexical variables |
52 | In this module, coroutines are defined as "callchain + lexical variables + |
27 | + @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own |
53 | @_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain, |
28 | callchain, it's own set of lexicals and it's own set of perl's most |
54 | its own set of lexicals and its own set of perls most important global |
29 | important global variables. |
55 | variables (see L<Coro::State> for more configuration). |
30 | |
56 | |
31 | =cut |
57 | =cut |
32 | |
58 | |
33 | package Coro; |
59 | package Coro; |
34 | |
60 | |
35 | use strict; |
61 | use strict qw(vars subs); |
36 | no warnings "uninitialized"; |
62 | no warnings "uninitialized"; |
37 | |
63 | |
38 | use Coro::State; |
64 | use Coro::State; |
39 | |
65 | |
40 | use base qw(Coro::State Exporter); |
66 | use base qw(Coro::State Exporter); |
41 | |
67 | |
42 | our $idle; # idle handler |
68 | our $idle; # idle handler |
43 | our $main; # main coroutine |
69 | our $main; # main coroutine |
44 | our $current; # current coroutine |
70 | our $current; # current coroutine |
45 | |
71 | |
46 | our $VERSION = '2.5'; |
72 | our $VERSION = 4.911; |
47 | |
73 | |
48 | our @EXPORT = qw(async cede schedule terminate current); |
74 | our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); |
49 | our %EXPORT_TAGS = ( |
75 | our %EXPORT_TAGS = ( |
50 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
76 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
51 | ); |
77 | ); |
52 | our @EXPORT_OK = @{$EXPORT_TAGS{prio}}; |
78 | our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready)); |
53 | |
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54 | { |
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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 | |
79 | |
88 | =over 4 |
80 | =over 4 |
89 | |
81 | |
90 | =item $main |
82 | =item $Coro::main |
91 | |
83 | |
92 | This coroutine represents the main program. |
84 | This variable stores the coroutine object that represents the main |
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85 | program. While you cna C<ready> it and do most other things you can do to |
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86 | coroutines, it is mainly useful to compare again C<$Coro::current>, to see |
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87 | whether you are running in the main program or not. |
93 | |
88 | |
94 | =cut |
89 | =cut |
95 | |
90 | |
96 | $main = new Coro; |
91 | $main = new Coro; |
97 | |
92 | |
98 | =item $current (or as function: current) |
93 | =item $Coro::current |
99 | |
94 | |
100 | The current coroutine (the last coroutine switched to). The initial value |
95 | The coroutine object representing the current coroutine (the last |
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96 | coroutine that the Coro scheduler switched to). The initial value is |
101 | is C<$main> (of course). |
97 | C<$main> (of course). |
102 | |
98 | |
103 | This variable is B<strictly> I<read-only>. It is provided for performance |
99 | 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 |
100 | value stored in it and use it as any other coroutine object, but you must |
105 | C<Coro::current> function instead. |
101 | not otherwise modify the variable itself. |
106 | |
102 | |
107 | =cut |
103 | =cut |
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104 | |
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105 | $main->{desc} = "[main::]"; |
108 | |
106 | |
109 | # maybe some other module used Coro::Specific before... |
107 | # maybe some other module used Coro::Specific before... |
110 | if ($current) { |
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111 | $main->{specific} = $current->{specific}; |
108 | $main->{_specific} = $current->{_specific} |
112 | } |
109 | if $current; |
113 | |
110 | |
114 | $current = $main; |
111 | _set_current $main; |
115 | |
112 | |
116 | sub current() { $current } |
113 | sub current() { $current } # [DEPRECATED] |
117 | |
114 | |
118 | =item $idle |
115 | =item $Coro::idle |
119 | |
116 | |
120 | A callback that is called whenever the scheduler finds no ready coroutines |
117 | This variable is mainly useful to integrate Coro into event loops. It is |
121 | to run. The default implementation prints "FATAL: deadlock detected" and |
118 | usually better to rely on L<Coro::AnyEvent> or LC<Coro::EV>, as this is |
122 | exits. |
119 | pretty low-level functionality. |
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120 | |
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121 | This variable stores a callback that is called whenever the scheduler |
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122 | finds no ready coroutines to run. The default implementation prints |
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123 | "FATAL: deadlock detected" and exits, because the program has no other way |
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124 | to continue. |
123 | |
125 | |
124 | This hook is overwritten by modules such as C<Coro::Timer> and |
126 | This hook is overwritten by modules such as C<Coro::Timer> and |
125 | C<Coro::Event> to wait on an external event that hopefully wakes up some |
127 | C<Coro::AnyEvent> to wait on an external event that hopefully wake up a |
126 | coroutine. |
128 | coroutine so the scheduler can run it. |
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129 | |
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130 | Note that the callback I<must not>, under any circumstances, block |
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131 | the current coroutine. Normally, this is achieved by having an "idle |
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132 | coroutine" that calls the event loop and then blocks again, and then |
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133 | readying that coroutine in the idle handler. |
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134 | |
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135 | See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this |
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136 | technique. |
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137 | |
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138 | Please note that if your callback recursively invokes perl (e.g. for event |
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139 | handlers), then it must be prepared to be called recursively itself. |
127 | |
140 | |
128 | =cut |
141 | =cut |
129 | |
142 | |
130 | $idle = sub { |
143 | $idle = sub { |
131 | print STDERR "FATAL: deadlock detected\n"; |
144 | require Carp; |
132 | exit (51); |
145 | Carp::croak ("FATAL: deadlock detected"); |
133 | }; |
146 | }; |
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147 | |
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148 | sub _cancel { |
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149 | my ($self) = @_; |
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150 | |
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151 | # free coroutine data and mark as destructed |
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152 | $self->_destroy |
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153 | or return; |
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154 | |
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155 | # call all destruction callbacks |
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156 | $_->(@{$self->{_status}}) |
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157 | for @{ delete $self->{_on_destroy} || [] }; |
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158 | } |
134 | |
159 | |
135 | # this coroutine is necessary because a coroutine |
160 | # this coroutine is necessary because a coroutine |
136 | # cannot destroy itself. |
161 | # cannot destroy itself. |
137 | my @destroy; |
162 | my @destroy; |
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163 | my $manager; |
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164 | |
138 | my $manager; $manager = new Coro sub { |
165 | $manager = new Coro sub { |
139 | while () { |
166 | while () { |
140 | # by overwriting the state object with the manager we destroy it |
167 | (shift @destroy)->_cancel |
141 | # while still being able to schedule this coroutine (in case it has |
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142 | # been readied multiple times. this is harmless since the manager |
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143 | # can be called as many times as neccessary and will always |
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144 | # remove itself from the runqueue |
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145 | while (@destroy) { |
168 | while @destroy; |
146 | my $coro = pop @destroy; |
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147 | $coro->{status} ||= []; |
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148 | $_->ready for @{delete $coro->{join} || []}; |
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149 | |
169 | |
150 | # the next line destroys the coro state, but keeps the |
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151 | # process itself intact (we basically make it a zombie |
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152 | # process that always runs the manager thread, so it's possible |
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153 | # to transfer() to this process). |
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154 | $coro->_clone_state_from ($manager); |
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155 | } |
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156 | &schedule; |
170 | &schedule; |
157 | } |
171 | } |
158 | }; |
172 | }; |
159 | |
173 | $manager->{desc} = "[coro manager]"; |
160 | # static methods. not really. |
174 | $manager->prio (PRIO_MAX); |
161 | |
175 | |
162 | =back |
176 | =back |
163 | |
177 | |
164 | =head2 STATIC METHODS |
178 | =head2 SIMPLE COROUTINE CREATION |
165 | |
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166 | Static methods are actually functions that operate on the current process only. |
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167 | |
179 | |
168 | =over 4 |
180 | =over 4 |
169 | |
181 | |
170 | =item async { ... } [@args...] |
182 | =item async { ... } [@args...] |
171 | |
183 | |
172 | Create a new asynchronous process and return it's process object |
184 | Create a new coroutine and return it's coroutine object (usually |
173 | (usually unused). When the sub returns the new process is automatically |
185 | unused). The coroutine will be put into the ready queue, so |
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186 | it will start running automatically on the next scheduler run. |
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187 | |
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188 | The first argument is a codeblock/closure that should be executed in the |
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189 | coroutine. When it returns argument returns the coroutine is automatically |
174 | terminated. |
190 | terminated. |
175 | |
191 | |
176 | When the coroutine dies, the program will exit, just as in the main |
192 | The remaining arguments are passed as arguments to the closure. |
177 | program. |
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178 | |
193 | |
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194 | See the C<Coro::State::new> constructor for info about the coroutine |
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195 | environment in which coroutines are executed. |
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196 | |
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197 | Calling C<exit> in a coroutine will do the same as calling exit outside |
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198 | the coroutine. Likewise, when the coroutine dies, the program will exit, |
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199 | just as it would in the main program. |
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200 | |
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201 | If you do not want that, you can provide a default C<die> handler, or |
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202 | simply avoid dieing (by use of C<eval>). |
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203 | |
179 | # create a new coroutine that just prints its arguments |
204 | Example: Create a new coroutine that just prints its arguments. |
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205 | |
180 | async { |
206 | async { |
181 | print "@_\n"; |
207 | print "@_\n"; |
182 | } 1,2,3,4; |
208 | } 1,2,3,4; |
183 | |
209 | |
184 | =cut |
210 | =cut |
185 | |
211 | |
186 | sub async(&@) { |
212 | sub async(&@) { |
187 | my $pid = new Coro @_; |
213 | my $coro = new Coro @_; |
188 | $pid->ready; |
214 | $coro->ready; |
189 | $pid |
215 | $coro |
190 | } |
216 | } |
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217 | |
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218 | =item async_pool { ... } [@args...] |
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219 | |
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220 | Similar to C<async>, but uses a coroutine pool, so you should not call |
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221 | terminate or join on it (although you are allowed to), and you get a |
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222 | coroutine that might have executed other code already (which can be good |
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223 | or bad :). |
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224 | |
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225 | On the plus side, this function is faster than creating (and destroying) |
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226 | a completly new coroutine, so if you need a lot of generic coroutines in |
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227 | quick successsion, use C<async_pool>, not C<async>. |
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228 | |
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229 | The code block is executed in an C<eval> context and a warning will be |
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230 | issued in case of an exception instead of terminating the program, as |
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231 | C<async> does. As the coroutine is being reused, stuff like C<on_destroy> |
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232 | will not work in the expected way, unless you call terminate or cancel, |
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233 | which somehow defeats the purpose of pooling (but is fine in the |
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234 | exceptional case). |
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235 | |
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236 | The priority will be reset to C<0> after each run, tracing will be |
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237 | disabled, the description will be reset and the default output filehandle |
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238 | gets restored, so you can change all these. Otherwise the coroutine will |
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239 | be re-used "as-is": most notably if you change other per-coroutine global |
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240 | stuff such as C<$/> you I<must needs> revert that change, which is most |
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241 | simply done by using local as in: C<< local $/ >>. |
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242 | |
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243 | The idle pool size is limited to C<8> idle coroutines (this can be |
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244 | adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle |
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245 | coros as required. |
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246 | |
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247 | If you are concerned about pooled coroutines growing a lot because a |
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248 | single C<async_pool> used a lot of stackspace you can e.g. C<async_pool |
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249 | { terminate }> once per second or so to slowly replenish the pool. In |
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250 | addition to that, when the stacks used by a handler grows larger than 16kb |
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251 | (adjustable via $Coro::POOL_RSS) it will also be destroyed. |
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252 | |
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253 | =cut |
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254 | |
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255 | our $POOL_SIZE = 8; |
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256 | our $POOL_RSS = 16 * 1024; |
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257 | our @async_pool; |
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258 | |
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259 | sub pool_handler { |
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260 | my $cb; |
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261 | |
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262 | while () { |
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263 | eval { |
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264 | while () { |
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265 | _pool_1 $cb; |
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266 | &$cb; |
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267 | _pool_2 $cb; |
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268 | &schedule; |
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269 | } |
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270 | }; |
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271 | |
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272 | if ($@) { |
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273 | last if $@ eq "\3async_pool terminate\2\n"; |
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274 | warn $@; |
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275 | } |
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276 | } |
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277 | } |
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278 | |
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279 | sub async_pool(&@) { |
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280 | # this is also inlined into the unlock_scheduler |
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281 | my $coro = (pop @async_pool) || new Coro \&pool_handler; |
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282 | |
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283 | $coro->{_invoke} = [@_]; |
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284 | $coro->ready; |
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285 | |
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286 | $coro |
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287 | } |
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288 | |
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289 | =back |
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290 | |
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291 | =head2 STATIC METHODS |
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292 | |
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293 | Static methods are actually functions that operate on the current coroutine. |
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294 | |
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295 | =over 4 |
191 | |
296 | |
192 | =item schedule |
297 | =item schedule |
193 | |
298 | |
194 | Calls the scheduler. Please note that the current process will not be put |
299 | Calls the scheduler. The scheduler will find the next coroutine that is |
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300 | to be run from the ready queue and switches to it. The next coroutine |
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301 | to be run is simply the one with the highest priority that is longest |
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302 | in its ready queue. If there is no coroutine ready, it will clal the |
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303 | C<$Coro::idle> hook. |
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304 | |
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305 | Please note that the current coroutine will I<not> be put into the ready |
195 | into the ready queue, so calling this function usually means you will |
306 | queue, so calling this function usually means you will never be called |
196 | never be called again. |
307 | again unless something else (e.g. an event handler) calls C<< ->ready >>, |
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308 | thus waking you up. |
197 | |
309 | |
198 | =cut |
310 | This makes C<schedule> I<the> generic method to use to block the current |
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311 | coroutine and wait for events: first you remember the current coroutine in |
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312 | a variable, then arrange for some callback of yours to call C<< ->ready |
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313 | >> on that once some event happens, and last you call C<schedule> to put |
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314 | yourself to sleep. Note that a lot of things can wake your coroutine up, |
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315 | so you need to check whether the event indeed happened, e.g. by storing the |
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316 | status in a variable. |
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317 | |
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318 | The canonical way to wait on external events is this: |
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319 | |
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320 | { |
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321 | # remember current coroutine |
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322 | my $current = $Coro::current; |
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323 | |
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324 | # register a hypothetical event handler |
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325 | on_event_invoke sub { |
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326 | # wake up sleeping coroutine |
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327 | $current->ready; |
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328 | undef $current; |
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329 | }; |
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330 | |
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331 | # call schedule until event occurred. |
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332 | # in case we are woken up for other reasons |
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333 | # (current still defined), loop. |
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334 | Coro::schedule while $current; |
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335 | } |
199 | |
336 | |
200 | =item cede |
337 | =item cede |
201 | |
338 | |
202 | "Cede" to other processes. This function puts the current process into the |
339 | "Cede" to other coroutines. This function puts the current coroutine into |
203 | ready queue and calls C<schedule>, which has the effect of giving up the |
340 | the ready queue and calls C<schedule>, which has the effect of giving |
204 | current "timeslice" to other coroutines of the same or higher priority. |
341 | up the current "timeslice" to other coroutines of the same or higher |
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342 | priority. Once your coroutine gets its turn again it will automatically be |
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343 | resumed. |
205 | |
344 | |
206 | =cut |
345 | This function is often called C<yield> in other languages. |
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346 | |
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347 | =item Coro::cede_notself |
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348 | |
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349 | Works like cede, but is not exported by default and will cede to I<any> |
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350 | coroutine, regardless of priority. This is useful sometimes to ensure |
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351 | progress is made. |
207 | |
352 | |
208 | =item terminate [arg...] |
353 | =item terminate [arg...] |
209 | |
354 | |
210 | Terminates the current process with the given status values (see L<cancel>). |
355 | Terminates the current coroutine with the given status values (see L<cancel>). |
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356 | |
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357 | =item killall |
|
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358 | |
|
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359 | Kills/terminates/cancels all coroutines except the currently running |
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360 | one. This is useful after a fork, either in the child or the parent, as |
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361 | usually only one of them should inherit the running coroutines. |
|
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362 | |
|
|
363 | Note that while this will try to free some of the main programs resources, |
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364 | you cannot free all of them, so if a coroutine that is not the main |
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365 | program calls this function, there will be some one-time resource leak. |
211 | |
366 | |
212 | =cut |
367 | =cut |
213 | |
368 | |
214 | sub terminate { |
369 | sub terminate { |
215 | $current->cancel (@_); |
370 | $current->cancel (@_); |
216 | } |
371 | } |
217 | |
372 | |
|
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373 | sub killall { |
|
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374 | for (Coro::State::list) { |
|
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375 | $_->cancel |
|
|
376 | if $_ != $current && UNIVERSAL::isa $_, "Coro"; |
|
|
377 | } |
|
|
378 | } |
|
|
379 | |
218 | =back |
380 | =back |
219 | |
381 | |
220 | # dynamic methods |
|
|
221 | |
|
|
222 | =head2 PROCESS METHODS |
382 | =head2 COROUTINE METHODS |
223 | |
383 | |
224 | These are the methods you can call on process objects. |
384 | These are the methods you can call on coroutine objects (or to create |
|
|
385 | them). |
225 | |
386 | |
226 | =over 4 |
387 | =over 4 |
227 | |
388 | |
228 | =item new Coro \&sub [, @args...] |
389 | =item new Coro \&sub [, @args...] |
229 | |
390 | |
230 | Create a new process and return it. When the sub returns the process |
391 | Create a new coroutine and return it. When the sub returns, the coroutine |
231 | automatically terminates as if C<terminate> with the returned values were |
392 | automatically terminates as if C<terminate> with the returned values were |
232 | called. To make the process run you must first put it into the ready queue |
393 | called. To make the coroutine run you must first put it into the ready |
233 | by calling the ready method. |
394 | queue by calling the ready method. |
234 | |
395 | |
235 | =cut |
396 | See C<async> and C<Coro::State::new> for additional info about the |
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397 | coroutine environment. |
236 | |
398 | |
|
|
399 | =cut |
|
|
400 | |
237 | sub _new_coro { |
401 | sub _run_coro { |
238 | $current->_clear_idle_sp; # (re-)set the idle sp on the following cede |
|
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239 | _set_cede_self; # ensures that cede cede's us first |
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240 | cede; |
|
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241 | terminate &{+shift}; |
402 | terminate &{+shift}; |
242 | } |
403 | } |
243 | |
404 | |
244 | sub new { |
405 | sub new { |
245 | my $class = shift; |
406 | my $class = shift; |
246 | |
407 | |
247 | $class->SUPER::new (\&_new_coro, @_) |
408 | $class->SUPER::new (\&_run_coro, @_) |
248 | } |
409 | } |
249 | |
410 | |
250 | =item $process->ready |
411 | =item $success = $coroutine->ready |
251 | |
412 | |
252 | Put the given process into the ready queue. |
413 | Put the given coroutine into the end of its ready queue (there is one |
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414 | queue for each priority) and return true. If the coroutine is already in |
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415 | the ready queue, do nothing and return false. |
253 | |
416 | |
254 | =cut |
417 | This ensures that the scheduler will resume this coroutine automatically |
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418 | once all the coroutines of higher priority and all coroutines of the same |
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419 | priority that were put into the ready queue earlier have been resumed. |
255 | |
420 | |
|
|
421 | =item $is_ready = $coroutine->is_ready |
|
|
422 | |
|
|
423 | Return whether the coroutine is currently the ready queue or not, |
|
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424 | |
256 | =item $process->cancel (arg...) |
425 | =item $coroutine->cancel (arg...) |
257 | |
426 | |
258 | Terminates the given process and makes it return the given arguments as |
427 | Terminates the given coroutine and makes it return the given arguments as |
259 | status (default: the empty list). |
428 | status (default: the empty list). Never returns if the coroutine is the |
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429 | current coroutine. |
260 | |
430 | |
261 | =cut |
431 | =cut |
262 | |
432 | |
263 | sub cancel { |
433 | sub cancel { |
264 | my $self = shift; |
434 | my $self = shift; |
265 | $self->{status} = [@_]; |
435 | $self->{_status} = [@_]; |
|
|
436 | |
|
|
437 | if ($current == $self) { |
266 | push @destroy, $self; |
438 | push @destroy, $self; |
267 | $manager->ready; |
439 | $manager->ready; |
268 | &schedule if $current == $self; |
440 | &schedule while 1; |
|
|
441 | } else { |
|
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442 | $self->_cancel; |
|
|
443 | } |
269 | } |
444 | } |
270 | |
445 | |
|
|
446 | =item $coroutine->throw ([$scalar]) |
|
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447 | |
|
|
448 | If C<$throw> is specified and defined, it will be thrown as an exception |
|
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449 | inside the coroutine at the next convenient point in time (usually after |
|
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450 | it gains control at the next schedule/transfer/cede). Otherwise clears the |
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451 | exception object. |
|
|
452 | |
|
|
453 | The exception object will be thrown "as is" with the specified scalar in |
|
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454 | C<$@>, i.e. if it is a string, no line number or newline will be appended |
|
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455 | (unlike with C<die>). |
|
|
456 | |
|
|
457 | This can be used as a softer means than C<cancel> to ask a coroutine to |
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458 | end itself, although there is no guarantee that the exception will lead to |
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459 | termination, and if the exception isn't caught it might well end the whole |
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460 | program. |
|
|
461 | |
|
|
462 | You might also think of C<throw> as being the moral equivalent of |
|
|
463 | C<kill>ing a coroutine with a signal (in this case, a scalar). |
|
|
464 | |
271 | =item $process->join |
465 | =item $coroutine->join |
272 | |
466 | |
273 | Wait until the coroutine terminates and return any values given to the |
467 | Wait until the coroutine terminates and return any values given to the |
274 | C<terminate> or C<cancel> functions. C<join> can be called multiple times |
468 | C<terminate> or C<cancel> functions. C<join> can be called concurrently |
275 | from multiple processes. |
469 | from multiple coroutines, and all will be resumed and given the status |
|
|
470 | return once the C<$coroutine> terminates. |
276 | |
471 | |
277 | =cut |
472 | =cut |
278 | |
473 | |
279 | sub join { |
474 | sub join { |
280 | my $self = shift; |
475 | my $self = shift; |
|
|
476 | |
281 | unless ($self->{status}) { |
477 | unless ($self->{_status}) { |
282 | push @{$self->{join}}, $current; |
478 | my $current = $current; |
283 | &schedule; |
479 | |
|
|
480 | push @{$self->{_on_destroy}}, sub { |
|
|
481 | $current->ready; |
|
|
482 | undef $current; |
|
|
483 | }; |
|
|
484 | |
|
|
485 | &schedule while $current; |
284 | } |
486 | } |
|
|
487 | |
285 | wantarray ? @{$self->{status}} : $self->{status}[0]; |
488 | wantarray ? @{$self->{_status}} : $self->{_status}[0]; |
286 | } |
489 | } |
287 | |
490 | |
|
|
491 | =item $coroutine->on_destroy (\&cb) |
|
|
492 | |
|
|
493 | Registers a callback that is called when this coroutine gets destroyed, |
|
|
494 | but before it is joined. The callback gets passed the terminate arguments, |
|
|
495 | if any, and I<must not> die, under any circumstances. |
|
|
496 | |
|
|
497 | =cut |
|
|
498 | |
|
|
499 | sub on_destroy { |
|
|
500 | my ($self, $cb) = @_; |
|
|
501 | |
|
|
502 | push @{ $self->{_on_destroy} }, $cb; |
|
|
503 | } |
|
|
504 | |
288 | =item $oldprio = $process->prio ($newprio) |
505 | =item $oldprio = $coroutine->prio ($newprio) |
289 | |
506 | |
290 | Sets (or gets, if the argument is missing) the priority of the |
507 | Sets (or gets, if the argument is missing) the priority of the |
291 | process. Higher priority processes get run before lower priority |
508 | coroutine. Higher priority coroutines get run before lower priority |
292 | processes. Priorities are small signed integers (currently -4 .. +3), |
509 | coroutines. Priorities are small signed integers (currently -4 .. +3), |
293 | that you can refer to using PRIO_xxx constants (use the import tag :prio |
510 | that you can refer to using PRIO_xxx constants (use the import tag :prio |
294 | to get then): |
511 | to get then): |
295 | |
512 | |
296 | PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN |
513 | PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN |
297 | 3 > 1 > 0 > -1 > -3 > -4 |
514 | 3 > 1 > 0 > -1 > -3 > -4 |
… | |
… | |
300 | current->prio(PRIO_HIGH); |
517 | current->prio(PRIO_HIGH); |
301 | |
518 | |
302 | The idle coroutine ($Coro::idle) always has a lower priority than any |
519 | The idle coroutine ($Coro::idle) always has a lower priority than any |
303 | existing coroutine. |
520 | existing coroutine. |
304 | |
521 | |
305 | Changing the priority of the current process will take effect immediately, |
522 | Changing the priority of the current coroutine will take effect immediately, |
306 | but changing the priority of processes in the ready queue (but not |
523 | but changing the priority of coroutines in the ready queue (but not |
307 | running) will only take effect after the next schedule (of that |
524 | running) will only take effect after the next schedule (of that |
308 | process). This is a bug that will be fixed in some future version. |
525 | coroutine). This is a bug that will be fixed in some future version. |
309 | |
526 | |
310 | =item $newprio = $process->nice ($change) |
527 | =item $newprio = $coroutine->nice ($change) |
311 | |
528 | |
312 | Similar to C<prio>, but subtract the given value from the priority (i.e. |
529 | Similar to C<prio>, but subtract the given value from the priority (i.e. |
313 | higher values mean lower priority, just as in unix). |
530 | higher values mean lower priority, just as in unix). |
314 | |
531 | |
315 | =item $olddesc = $process->desc ($newdesc) |
532 | =item $olddesc = $coroutine->desc ($newdesc) |
316 | |
533 | |
317 | Sets (or gets in case the argument is missing) the description for this |
534 | Sets (or gets in case the argument is missing) the description for this |
318 | process. This is just a free-form string you can associate with a process. |
535 | coroutine. This is just a free-form string you can associate with a |
|
|
536 | coroutine. |
|
|
537 | |
|
|
538 | This method simply sets the C<< $coroutine->{desc} >> member to the given |
|
|
539 | string. You can modify this member directly if you wish. |
319 | |
540 | |
320 | =cut |
541 | =cut |
321 | |
542 | |
322 | sub desc { |
543 | sub desc { |
323 | my $old = $_[0]{desc}; |
544 | my $old = $_[0]{desc}; |
… | |
… | |
325 | $old; |
546 | $old; |
326 | } |
547 | } |
327 | |
548 | |
328 | =back |
549 | =back |
329 | |
550 | |
|
|
551 | =head2 GLOBAL FUNCTIONS |
|
|
552 | |
|
|
553 | =over 4 |
|
|
554 | |
|
|
555 | =item Coro::nready |
|
|
556 | |
|
|
557 | Returns the number of coroutines that are currently in the ready state, |
|
|
558 | i.e. that can be switched to by calling C<schedule> directory or |
|
|
559 | indirectly. The value C<0> means that the only runnable coroutine is the |
|
|
560 | currently running one, so C<cede> would have no effect, and C<schedule> |
|
|
561 | would cause a deadlock unless there is an idle handler that wakes up some |
|
|
562 | coroutines. |
|
|
563 | |
|
|
564 | =item my $guard = Coro::guard { ... } |
|
|
565 | |
|
|
566 | This creates and returns a guard object. Nothing happens until the object |
|
|
567 | gets destroyed, in which case the codeblock given as argument will be |
|
|
568 | executed. This is useful to free locks or other resources in case of a |
|
|
569 | runtime error or when the coroutine gets canceled, as in both cases the |
|
|
570 | guard block will be executed. The guard object supports only one method, |
|
|
571 | C<< ->cancel >>, which will keep the codeblock from being executed. |
|
|
572 | |
|
|
573 | Example: set some flag and clear it again when the coroutine gets canceled |
|
|
574 | or the function returns: |
|
|
575 | |
|
|
576 | sub do_something { |
|
|
577 | my $guard = Coro::guard { $busy = 0 }; |
|
|
578 | $busy = 1; |
|
|
579 | |
|
|
580 | # do something that requires $busy to be true |
|
|
581 | } |
|
|
582 | |
|
|
583 | =cut |
|
|
584 | |
|
|
585 | sub guard(&) { |
|
|
586 | bless \(my $cb = $_[0]), "Coro::guard" |
|
|
587 | } |
|
|
588 | |
|
|
589 | sub Coro::guard::cancel { |
|
|
590 | ${$_[0]} = sub { }; |
|
|
591 | } |
|
|
592 | |
|
|
593 | sub Coro::guard::DESTROY { |
|
|
594 | ${$_[0]}->(); |
|
|
595 | } |
|
|
596 | |
|
|
597 | |
|
|
598 | =item unblock_sub { ... } |
|
|
599 | |
|
|
600 | This utility function takes a BLOCK or code reference and "unblocks" it, |
|
|
601 | returning a new coderef. Unblocking means that calling the new coderef |
|
|
602 | will return immediately without blocking, returning nothing, while the |
|
|
603 | original code ref will be called (with parameters) from within another |
|
|
604 | coroutine. |
|
|
605 | |
|
|
606 | The reason this function exists is that many event libraries (such as the |
|
|
607 | venerable L<Event|Event> module) are not coroutine-safe (a weaker form |
|
|
608 | of thread-safety). This means you must not block within event callbacks, |
|
|
609 | otherwise you might suffer from crashes or worse. The only event library |
|
|
610 | currently known that is safe to use without C<unblock_sub> is L<EV>. |
|
|
611 | |
|
|
612 | This function allows your callbacks to block by executing them in another |
|
|
613 | coroutine where it is safe to block. One example where blocking is handy |
|
|
614 | is when you use the L<Coro::AIO|Coro::AIO> functions to save results to |
|
|
615 | disk, for example. |
|
|
616 | |
|
|
617 | In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when |
|
|
618 | creating event callbacks that want to block. |
|
|
619 | |
|
|
620 | If your handler does not plan to block (e.g. simply sends a message to |
|
|
621 | another coroutine, or puts some other coroutine into the ready queue), |
|
|
622 | there is no reason to use C<unblock_sub>. |
|
|
623 | |
|
|
624 | Note that you also need to use C<unblock_sub> for any other callbacks that |
|
|
625 | are indirectly executed by any C-based event loop. For example, when you |
|
|
626 | use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it |
|
|
627 | provides callbacks that are the result of some event callback, then you |
|
|
628 | must not block either, or use C<unblock_sub>. |
|
|
629 | |
|
|
630 | =cut |
|
|
631 | |
|
|
632 | our @unblock_queue; |
|
|
633 | |
|
|
634 | # we create a special coro because we want to cede, |
|
|
635 | # to reduce pressure on the coro pool (because most callbacks |
|
|
636 | # return immediately and can be reused) and because we cannot cede |
|
|
637 | # inside an event callback. |
|
|
638 | our $unblock_scheduler = new Coro sub { |
|
|
639 | while () { |
|
|
640 | while (my $cb = pop @unblock_queue) { |
|
|
641 | # this is an inlined copy of async_pool |
|
|
642 | my $coro = (pop @async_pool) || new Coro \&pool_handler; |
|
|
643 | |
|
|
644 | $coro->{_invoke} = $cb; |
|
|
645 | $coro->ready; |
|
|
646 | cede; # for short-lived callbacks, this reduces pressure on the coro pool |
|
|
647 | } |
|
|
648 | schedule; # sleep well |
|
|
649 | } |
|
|
650 | }; |
|
|
651 | $unblock_scheduler->{desc} = "[unblock_sub scheduler]"; |
|
|
652 | |
|
|
653 | sub unblock_sub(&) { |
|
|
654 | my $cb = shift; |
|
|
655 | |
|
|
656 | sub { |
|
|
657 | unshift @unblock_queue, [$cb, @_]; |
|
|
658 | $unblock_scheduler->ready; |
|
|
659 | } |
|
|
660 | } |
|
|
661 | |
|
|
662 | =back |
|
|
663 | |
330 | =cut |
664 | =cut |
331 | |
665 | |
332 | 1; |
666 | 1; |
333 | |
667 | |
334 | =head1 BUGS/LIMITATIONS |
668 | =head1 BUGS/LIMITATIONS |
335 | |
669 | |
336 | - you must make very sure that no coro is still active on global |
|
|
337 | destruction. very bad things might happen otherwise (usually segfaults). |
|
|
338 | |
|
|
339 | - this module is not thread-safe. You should only ever use this module |
670 | This module is not perl-pseudo-thread-safe. You should only ever use this |
340 | from the same thread (this requirement might be losened in the future |
671 | module from the same thread (this requirement might be removed in the |
341 | to allow per-thread schedulers, but Coro::State does not yet allow |
672 | future to allow per-thread schedulers, but Coro::State does not yet allow |
342 | this). |
673 | this). I recommend disabling thread support and using processes, as this |
|
|
674 | is much faster and uses less memory. |
343 | |
675 | |
344 | =head1 SEE ALSO |
676 | =head1 SEE ALSO |
345 | |
677 | |
|
|
678 | Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>. |
|
|
679 | |
|
|
680 | Debugging: L<Coro::Debug>. |
|
|
681 | |
346 | Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>. |
682 | Support/Utility: L<Coro::Specific>, L<Coro::Util>. |
347 | |
683 | |
348 | Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>. |
684 | Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>. |
349 | |
685 | |
350 | Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>. |
686 | IO/Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>. |
351 | |
687 | |
352 | Embedding: L<Coro:MakeMaker> |
688 | Compatibility: L<Coro::LWP>, L<Coro::BDB>, L<Coro::Storable>, L<Coro::Select>. |
|
|
689 | |
|
|
690 | XS API: L<Coro::MakeMaker>. |
|
|
691 | |
|
|
692 | Low level Configuration, Coroutine Environment: L<Coro::State>. |
353 | |
693 | |
354 | =head1 AUTHOR |
694 | =head1 AUTHOR |
355 | |
695 | |
356 | Marc Lehmann <schmorp@schmorp.de> |
696 | Marc Lehmann <schmorp@schmorp.de> |
357 | http://home.schmorp.de/ |
697 | http://home.schmorp.de/ |