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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 | |
26 | This module is still experimental, see the BUGS section below. |
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. |
27 | |
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 | |
28 | In this module, coroutines are defined as "callchain + lexical variables |
52 | In this module, coroutines are defined as "callchain + lexical variables + |
29 | + @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own |
53 | @_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain, |
30 | 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 |
31 | important global variables. |
55 | variables (see L<Coro::State> for more configuration). |
32 | |
56 | |
33 | =cut |
57 | =cut |
34 | |
58 | |
35 | package Coro; |
59 | package Coro; |
36 | |
60 | |
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61 | use strict qw(vars subs); |
37 | no warnings qw(uninitialized); |
62 | no warnings "uninitialized"; |
38 | |
63 | |
39 | use Coro::State; |
64 | use Coro::State; |
40 | |
65 | |
41 | use base Exporter; |
66 | use base qw(Coro::State Exporter); |
42 | |
67 | |
43 | $VERSION = 0.51; |
68 | our $idle; # idle handler |
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69 | our $main; # main coroutine |
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70 | our $current; # current coroutine |
44 | |
71 | |
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72 | our $VERSION = 5.0; |
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73 | |
45 | @EXPORT = qw(async cede schedule terminate current); |
74 | our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); |
46 | %EXPORT_TAGS = ( |
75 | our %EXPORT_TAGS = ( |
47 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
76 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
48 | ); |
77 | ); |
49 | @EXPORT_OK = @{$EXPORT_TAGS{prio}}; |
78 | our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready)); |
50 | |
79 | |
51 | { |
80 | =over 4 |
52 | my @async; |
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53 | my $init; |
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54 | |
81 | |
55 | # this way of handling attributes simply is NOT scalable ;() |
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56 | sub import { |
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57 | Coro->export_to_level(1, @_); |
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58 | my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE}; |
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59 | *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub { |
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60 | my ($package, $ref) = (shift, shift); |
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61 | my @attrs; |
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62 | for (@_) { |
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63 | if ($_ eq "Coro") { |
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64 | push @async, $ref; |
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65 | unless ($init++) { |
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66 | eval q{ |
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67 | sub INIT { |
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68 | &async(pop @async) while @async; |
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69 | } |
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70 | }; |
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71 | } |
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72 | } else { |
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73 | push @attrs, $_; |
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74 | } |
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75 | } |
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76 | return $old ? $old->($package, $ref, @attrs) : @attrs; |
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77 | }; |
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78 | } |
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79 | |
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80 | } |
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81 | |
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82 | =item $main |
82 | =item $Coro::main |
83 | |
83 | |
84 | This coroutine represents the main program. |
84 | This variable stores the coroutine object that represents the main |
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85 | program. While you cna C<ready> it and do most other things you can do to |
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86 | coroutines, it is mainly useful to compare again C<$Coro::current>, to see |
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87 | whether you are running in the main program or not. |
85 | |
88 | |
86 | =cut |
89 | =cut |
87 | |
90 | |
88 | our $main = new Coro; |
91 | # $main is now being initialised by Coro::State |
89 | |
92 | |
90 | =item $current (or as function: current) |
93 | =item $Coro::current |
91 | |
94 | |
92 | The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course). |
95 | The coroutine object representing the current coroutine (the last |
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96 | coroutine that the Coro scheduler switched to). The initial value is |
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97 | C<$Coro::main> (of course). |
93 | |
98 | |
94 | =cut |
99 | This variable is B<strictly> I<read-only>. You can take copies of the |
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100 | value stored in it and use it as any other coroutine object, but you must |
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101 | not otherwise modify the variable itself. |
95 | |
102 | |
96 | # maybe some other module used Coro::Specific before... |
103 | =cut |
97 | if ($current) { |
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98 | $main->{specific} = $current->{specific}; |
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99 | } |
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100 | |
104 | |
101 | our $current = $main; |
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102 | |
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103 | sub current() { $current } |
105 | sub current() { $current } # [DEPRECATED] |
104 | |
106 | |
105 | =item $idle |
107 | =item $Coro::idle |
106 | |
108 | |
107 | The coroutine to switch to when no other coroutine is running. The default |
109 | This variable is mainly useful to integrate Coro into event loops. It is |
108 | implementation prints "FATAL: deadlock detected" and exits. |
110 | usually better to rely on L<Coro::AnyEvent> or LC<Coro::EV>, as this is |
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111 | pretty low-level functionality. |
109 | |
112 | |
110 | =cut |
113 | This variable stores a callback that is called whenever the scheduler |
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114 | finds no ready coroutines to run. The default implementation prints |
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115 | "FATAL: deadlock detected" and exits, because the program has no other way |
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116 | to continue. |
111 | |
117 | |
112 | # should be done using priorities :( |
118 | This hook is overwritten by modules such as C<Coro::Timer> and |
113 | our $idle = new Coro sub { |
119 | C<Coro::AnyEvent> to wait on an external event that hopefully wake up a |
114 | print STDERR "FATAL: deadlock detected\n"; |
120 | coroutine so the scheduler can run it. |
115 | exit(51); |
121 | |
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122 | Note that the callback I<must not>, under any circumstances, block |
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123 | the current coroutine. Normally, this is achieved by having an "idle |
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124 | coroutine" that calls the event loop and then blocks again, and then |
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125 | readying that coroutine in the idle handler. |
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126 | |
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127 | See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this |
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128 | technique. |
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129 | |
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130 | Please note that if your callback recursively invokes perl (e.g. for event |
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131 | handlers), then it must be prepared to be called recursively itself. |
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132 | |
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133 | =cut |
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134 | |
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135 | $idle = sub { |
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136 | require Carp; |
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137 | Carp::croak ("FATAL: deadlock detected"); |
116 | }; |
138 | }; |
117 | |
139 | |
118 | # this coroutine is necessary because a coroutine |
140 | # this coroutine is necessary because a coroutine |
119 | # cannot destroy itself. |
141 | # cannot destroy itself. |
120 | my @destroy; |
142 | our @destroy; |
121 | my $manager; |
143 | our $manager; |
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144 | |
122 | $manager = new Coro sub { |
145 | $manager = new Coro sub { |
123 | while() { |
146 | while () { |
124 | # by overwriting the state object with the manager we destroy it |
147 | Coro::_cancel shift @destroy |
125 | # while still being able to schedule this coroutine (in case it has |
148 | while @destroy; |
126 | # been readied multiple times. this is harmless since the manager |
149 | |
127 | # can be called as many times as neccessary and will always |
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128 | # remove itself from the runqueue |
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129 | (pop @destroy)->{_coro_state} = $manager->{_coro_state} while @destroy; |
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130 | &schedule; |
150 | &schedule; |
131 | } |
151 | } |
132 | }; |
152 | }; |
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153 | $manager->{desc} = "[coro manager]"; |
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154 | $manager->prio (PRIO_MAX); |
133 | |
155 | |
134 | # static methods. not really. |
156 | =back |
135 | |
157 | |
136 | =head2 STATIC METHODS |
158 | =head2 SIMPLE COROUTINE CREATION |
137 | |
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138 | Static methods are actually functions that operate on the current process only. |
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139 | |
159 | |
140 | =over 4 |
160 | =over 4 |
141 | |
161 | |
142 | =item async { ... } [@args...] |
162 | =item async { ... } [@args...] |
143 | |
163 | |
144 | Create a new asynchronous process and return it's process object |
164 | Create a new coroutine and return it's coroutine object (usually |
145 | (usually unused). When the sub returns the new process is automatically |
165 | unused). The coroutine will be put into the ready queue, so |
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166 | it will start running automatically on the next scheduler run. |
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167 | |
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168 | The first argument is a codeblock/closure that should be executed in the |
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169 | coroutine. When it returns argument returns the coroutine is automatically |
146 | terminated. |
170 | terminated. |
147 | |
171 | |
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172 | The remaining arguments are passed as arguments to the closure. |
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173 | |
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174 | See the C<Coro::State::new> constructor for info about the coroutine |
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175 | environment in which coroutines are executed. |
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176 | |
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177 | Calling C<exit> in a coroutine will do the same as calling exit outside |
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178 | the coroutine. Likewise, when the coroutine dies, the program will exit, |
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179 | just as it would in the main program. |
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180 | |
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181 | If you do not want that, you can provide a default C<die> handler, or |
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182 | simply avoid dieing (by use of C<eval>). |
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183 | |
148 | # create a new coroutine that just prints its arguments |
184 | Example: Create a new coroutine that just prints its arguments. |
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185 | |
149 | async { |
186 | async { |
150 | print "@_\n"; |
187 | print "@_\n"; |
151 | } 1,2,3,4; |
188 | } 1,2,3,4; |
152 | |
189 | |
153 | The coderef you submit MUST NOT be a closure that refers to variables |
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154 | in an outer scope. This does NOT work. Pass arguments into it instead. |
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155 | |
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156 | =cut |
190 | =cut |
157 | |
191 | |
158 | sub async(&@) { |
192 | sub async(&@) { |
159 | my $pid = new Coro @_; |
193 | my $coro = new Coro @_; |
160 | $manager->ready; # this ensures that the stack is cloned from the manager |
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161 | $pid->ready; |
194 | $coro->ready; |
162 | $pid; |
195 | $coro |
163 | } |
196 | } |
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197 | |
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198 | =item async_pool { ... } [@args...] |
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199 | |
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200 | Similar to C<async>, but uses a coroutine pool, so you should not call |
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201 | terminate or join on it (although you are allowed to), and you get a |
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202 | coroutine that might have executed other code already (which can be good |
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203 | or bad :). |
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204 | |
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205 | On the plus side, this function is about twice as fast as creating (and |
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206 | destroying) a completely new coroutine, so if you need a lot of generic |
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207 | coroutines in quick successsion, use C<async_pool>, not C<async>. |
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208 | |
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209 | The code block is executed in an C<eval> context and a warning will be |
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210 | issued in case of an exception instead of terminating the program, as |
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211 | C<async> does. As the coroutine is being reused, stuff like C<on_destroy> |
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212 | will not work in the expected way, unless you call terminate or cancel, |
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213 | which somehow defeats the purpose of pooling (but is fine in the |
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214 | exceptional case). |
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215 | |
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216 | The priority will be reset to C<0> after each run, tracing will be |
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217 | disabled, the description will be reset and the default output filehandle |
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218 | gets restored, so you can change all these. Otherwise the coroutine will |
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219 | be re-used "as-is": most notably if you change other per-coroutine global |
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220 | stuff such as C<$/> you I<must needs> revert that change, which is most |
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221 | simply done by using local as in: C<< local $/ >>. |
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222 | |
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223 | The idle pool size is limited to C<8> idle coroutines (this can be |
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224 | adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle |
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225 | coros as required. |
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226 | |
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227 | If you are concerned about pooled coroutines growing a lot because a |
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228 | single C<async_pool> used a lot of stackspace you can e.g. C<async_pool |
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229 | { terminate }> once per second or so to slowly replenish the pool. In |
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230 | addition to that, when the stacks used by a handler grows larger than 16kb |
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231 | (adjustable via $Coro::POOL_RSS) it will also be destroyed. |
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232 | |
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233 | =cut |
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234 | |
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235 | our $POOL_SIZE = 8; |
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236 | our $POOL_RSS = 16 * 1024; |
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237 | our @async_pool; |
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238 | |
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239 | sub pool_handler { |
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240 | while () { |
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241 | eval { |
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242 | &{&_pool_handler} while 1; |
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243 | }; |
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244 | |
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245 | warn $@ if $@; |
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246 | } |
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247 | } |
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248 | |
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249 | =back |
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250 | |
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251 | =head2 STATIC METHODS |
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252 | |
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253 | Static methods are actually functions that operate on the current coroutine. |
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254 | |
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255 | =over 4 |
164 | |
256 | |
165 | =item schedule |
257 | =item schedule |
166 | |
258 | |
167 | Calls the scheduler. Please note that the current process will not be put |
259 | Calls the scheduler. The scheduler will find the next coroutine that is |
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260 | to be run from the ready queue and switches to it. The next coroutine |
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261 | to be run is simply the one with the highest priority that is longest |
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262 | in its ready queue. If there is no coroutine ready, it will clal the |
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263 | C<$Coro::idle> hook. |
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264 | |
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265 | Please note that the current coroutine will I<not> be put into the ready |
168 | into the ready queue, so calling this function usually means you will |
266 | queue, so calling this function usually means you will never be called |
169 | never be called again. |
267 | again unless something else (e.g. an event handler) calls C<< ->ready >>, |
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268 | thus waking you up. |
170 | |
269 | |
171 | =cut |
270 | This makes C<schedule> I<the> generic method to use to block the current |
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271 | coroutine and wait for events: first you remember the current coroutine in |
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272 | a variable, then arrange for some callback of yours to call C<< ->ready |
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273 | >> on that once some event happens, and last you call C<schedule> to put |
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274 | yourself to sleep. Note that a lot of things can wake your coroutine up, |
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275 | so you need to check whether the event indeed happened, e.g. by storing the |
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276 | status in a variable. |
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277 | |
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278 | See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks. |
172 | |
279 | |
173 | =item cede |
280 | =item cede |
174 | |
281 | |
175 | "Cede" to other processes. This function puts the current process into the |
282 | "Cede" to other coroutines. This function puts the current coroutine into |
176 | ready queue and calls C<schedule>, which has the effect of giving up the |
283 | the ready queue and calls C<schedule>, which has the effect of giving |
177 | current "timeslice" to other coroutines of the same or higher priority. |
284 | up the current "timeslice" to other coroutines of the same or higher |
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285 | priority. Once your coroutine gets its turn again it will automatically be |
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286 | resumed. |
178 | |
287 | |
179 | =cut |
288 | This function is often called C<yield> in other languages. |
180 | |
289 | |
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290 | =item Coro::cede_notself |
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291 | |
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292 | Works like cede, but is not exported by default and will cede to I<any> |
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293 | coroutine, regardless of priority. This is useful sometimes to ensure |
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294 | progress is made. |
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295 | |
181 | =item terminate |
296 | =item terminate [arg...] |
182 | |
297 | |
183 | Terminates the current process. |
298 | Terminates the current coroutine with the given status values (see L<cancel>). |
184 | |
299 | |
185 | Future versions of this function will allow result arguments. |
300 | =item killall |
186 | |
301 | |
187 | =cut |
302 | Kills/terminates/cancels all coroutines except the currently running |
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303 | one. This is useful after a fork, either in the child or the parent, as |
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304 | usually only one of them should inherit the running coroutines. |
188 | |
305 | |
189 | sub terminate { |
306 | Note that while this will try to free some of the main programs resources, |
190 | $current->cancel; |
307 | you cannot free all of them, so if a coroutine that is not the main |
191 | &schedule; |
308 | program calls this function, there will be some one-time resource leak. |
192 | die; # NORETURN |
309 | |
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310 | =cut |
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311 | |
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312 | sub killall { |
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313 | for (Coro::State::list) { |
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314 | $_->cancel |
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315 | if $_ != $current && UNIVERSAL::isa $_, "Coro"; |
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316 | } |
193 | } |
317 | } |
194 | |
318 | |
195 | =back |
319 | =back |
196 | |
320 | |
197 | # dynamic methods |
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198 | |
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199 | =head2 PROCESS METHODS |
321 | =head2 COROUTINE METHODS |
200 | |
322 | |
201 | These are the methods you can call on process objects. |
323 | These are the methods you can call on coroutine objects (or to create |
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324 | them). |
202 | |
325 | |
203 | =over 4 |
326 | =over 4 |
204 | |
327 | |
205 | =item new Coro \&sub [, @args...] |
328 | =item new Coro \&sub [, @args...] |
206 | |
329 | |
207 | Create a new process and return it. When the sub returns the process |
330 | Create a new coroutine and return it. When the sub returns, the coroutine |
208 | automatically terminates. To start the process you must first put it into |
331 | automatically terminates as if C<terminate> with the returned values were |
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332 | called. To make the coroutine run you must first put it into the ready |
209 | the ready queue by calling the ready method. |
333 | queue by calling the ready method. |
210 | |
334 | |
211 | The coderef you submit MUST NOT be a closure that refers to variables |
335 | See C<async> and C<Coro::State::new> for additional info about the |
212 | in an outer scope. This does NOT work. Pass arguments into it instead. |
336 | coroutine environment. |
213 | |
337 | |
214 | =cut |
338 | =cut |
215 | |
339 | |
216 | sub _newcoro { |
340 | sub _terminate { |
217 | terminate &{+shift}; |
341 | terminate &{+shift}; |
218 | } |
342 | } |
219 | |
343 | |
220 | sub new { |
344 | =item $success = $coroutine->ready |
221 | my $class = shift; |
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222 | bless { |
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223 | _coro_state => (new Coro::State $_[0] && \&_newcoro, @_), |
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224 | }, $class; |
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225 | } |
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226 | |
345 | |
227 | =item $process->ready |
346 | Put the given coroutine into the end of its ready queue (there is one |
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347 | queue for each priority) and return true. If the coroutine is already in |
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348 | the ready queue, do nothing and return false. |
228 | |
349 | |
229 | Put the given process into the ready queue. |
350 | This ensures that the scheduler will resume this coroutine automatically |
|
|
351 | once all the coroutines of higher priority and all coroutines of the same |
|
|
352 | priority that were put into the ready queue earlier have been resumed. |
230 | |
353 | |
231 | =cut |
354 | =item $is_ready = $coroutine->is_ready |
232 | |
355 | |
233 | =item $process->cancel |
356 | Return whether the coroutine is currently the ready queue or not, |
234 | |
357 | |
235 | Like C<terminate>, but terminates the specified process instead. |
358 | =item $coroutine->cancel (arg...) |
|
|
359 | |
|
|
360 | Terminates the given coroutine and makes it return the given arguments as |
|
|
361 | status (default: the empty list). Never returns if the coroutine is the |
|
|
362 | current coroutine. |
236 | |
363 | |
237 | =cut |
364 | =cut |
238 | |
365 | |
239 | sub cancel { |
366 | sub cancel { |
240 | push @destroy, $_[0]; |
367 | my $self = shift; |
241 | $manager->ready; |
|
|
242 | &schedule if $current == $_[0]; |
|
|
243 | } |
|
|
244 | |
368 | |
|
|
369 | if ($current == $self) { |
|
|
370 | terminate @_; |
|
|
371 | } else { |
|
|
372 | $self->{_status} = [@_]; |
|
|
373 | $self->_cancel; |
|
|
374 | } |
|
|
375 | } |
|
|
376 | |
|
|
377 | =item $coroutine->schedule_to |
|
|
378 | |
|
|
379 | Puts the current coroutine to sleep (like C<Coro::schedule>), but instead |
|
|
380 | of continuing with the next coro from the ready queue, always switch to |
|
|
381 | the given coroutine object (regardless of priority etc.). The readyness |
|
|
382 | state of that coroutine isn't changed. |
|
|
383 | |
|
|
384 | This is an advanced method for special cases - I'd love to hear about any |
|
|
385 | uses for this one. |
|
|
386 | |
|
|
387 | =item $coroutine->cede_to |
|
|
388 | |
|
|
389 | Like C<schedule_to>, but puts the current coroutine into the ready |
|
|
390 | queue. This has the effect of temporarily switching to the given |
|
|
391 | coroutine, and continuing some time later. |
|
|
392 | |
|
|
393 | This is an advanced method for special cases - I'd love to hear about any |
|
|
394 | uses for this one. |
|
|
395 | |
|
|
396 | =item $coroutine->throw ([$scalar]) |
|
|
397 | |
|
|
398 | If C<$throw> is specified and defined, it will be thrown as an exception |
|
|
399 | inside the coroutine at the next convenient point in time. Otherwise |
|
|
400 | clears the exception object. |
|
|
401 | |
|
|
402 | Coro will check for the exception each time a schedule-like-function |
|
|
403 | returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down |
|
|
404 | >>, C<< Coro::Handle->readable >> and so on. Most of these functions |
|
|
405 | detect this case and return early in case an exception is pending. |
|
|
406 | |
|
|
407 | The exception object will be thrown "as is" with the specified scalar in |
|
|
408 | C<$@>, i.e. if it is a string, no line number or newline will be appended |
|
|
409 | (unlike with C<die>). |
|
|
410 | |
|
|
411 | This can be used as a softer means than C<cancel> to ask a coroutine to |
|
|
412 | end itself, although there is no guarantee that the exception will lead to |
|
|
413 | termination, and if the exception isn't caught it might well end the whole |
|
|
414 | program. |
|
|
415 | |
|
|
416 | You might also think of C<throw> as being the moral equivalent of |
|
|
417 | C<kill>ing a coroutine with a signal (in this case, a scalar). |
|
|
418 | |
|
|
419 | =item $coroutine->join |
|
|
420 | |
|
|
421 | Wait until the coroutine terminates and return any values given to the |
|
|
422 | C<terminate> or C<cancel> functions. C<join> can be called concurrently |
|
|
423 | from multiple coroutines, and all will be resumed and given the status |
|
|
424 | return once the C<$coroutine> terminates. |
|
|
425 | |
|
|
426 | =cut |
|
|
427 | |
|
|
428 | sub join { |
|
|
429 | my $self = shift; |
|
|
430 | |
|
|
431 | unless ($self->{_status}) { |
|
|
432 | my $current = $current; |
|
|
433 | |
|
|
434 | push @{$self->{_on_destroy}}, sub { |
|
|
435 | $current->ready; |
|
|
436 | undef $current; |
|
|
437 | }; |
|
|
438 | |
|
|
439 | &schedule while $current; |
|
|
440 | } |
|
|
441 | |
|
|
442 | wantarray ? @{$self->{_status}} : $self->{_status}[0]; |
|
|
443 | } |
|
|
444 | |
|
|
445 | =item $coroutine->on_destroy (\&cb) |
|
|
446 | |
|
|
447 | Registers a callback that is called when this coroutine gets destroyed, |
|
|
448 | but before it is joined. The callback gets passed the terminate arguments, |
|
|
449 | if any, and I<must not> die, under any circumstances. |
|
|
450 | |
|
|
451 | =cut |
|
|
452 | |
|
|
453 | sub on_destroy { |
|
|
454 | my ($self, $cb) = @_; |
|
|
455 | |
|
|
456 | push @{ $self->{_on_destroy} }, $cb; |
|
|
457 | } |
|
|
458 | |
245 | =item $oldprio = $process->prio($newprio) |
459 | =item $oldprio = $coroutine->prio ($newprio) |
246 | |
460 | |
247 | Sets the priority of the process. Higher priority processes get run before |
461 | Sets (or gets, if the argument is missing) the priority of the |
248 | lower priority processes. Priorities are smalled signed integer (currently |
462 | coroutine. Higher priority coroutines get run before lower priority |
|
|
463 | coroutines. Priorities are small signed integers (currently -4 .. +3), |
249 | -4 .. +3), that you can refer to using PRIO_xxx constants (use the import |
464 | that you can refer to using PRIO_xxx constants (use the import tag :prio |
250 | tag :prio to get then): |
465 | to get then): |
251 | |
466 | |
252 | PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN |
467 | PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN |
253 | 3 > 1 > 0 > -1 > -3 > -4 |
468 | 3 > 1 > 0 > -1 > -3 > -4 |
254 | |
469 | |
255 | # set priority to HIGH |
470 | # set priority to HIGH |
256 | current->prio(PRIO_HIGH); |
471 | current->prio(PRIO_HIGH); |
257 | |
472 | |
258 | The idle coroutine ($Coro::idle) always has a lower priority than any |
473 | The idle coroutine ($Coro::idle) always has a lower priority than any |
259 | existing coroutine. |
474 | existing coroutine. |
260 | |
475 | |
261 | Changing the priority of the current process will take effect immediately, |
476 | Changing the priority of the current coroutine will take effect immediately, |
262 | but changing the priority of processes in the ready queue (but not |
477 | but changing the priority of coroutines in the ready queue (but not |
263 | running) will only take effect after the next schedule (of that |
478 | running) will only take effect after the next schedule (of that |
264 | process). This is a bug that will be fixed in some future version. |
479 | coroutine). This is a bug that will be fixed in some future version. |
265 | |
480 | |
266 | =cut |
|
|
267 | |
|
|
268 | sub prio { |
|
|
269 | my $old = $_[0]{prio}; |
|
|
270 | $_[0]{prio} = $_[1] if @_ > 1; |
|
|
271 | $old; |
|
|
272 | } |
|
|
273 | |
|
|
274 | =item $newprio = $process->nice($change) |
481 | =item $newprio = $coroutine->nice ($change) |
275 | |
482 | |
276 | Similar to C<prio>, but subtract the given value from the priority (i.e. |
483 | Similar to C<prio>, but subtract the given value from the priority (i.e. |
277 | higher values mean lower priority, just as in unix). |
484 | higher values mean lower priority, just as in unix). |
278 | |
485 | |
279 | =cut |
486 | =item $olddesc = $coroutine->desc ($newdesc) |
280 | |
487 | |
281 | sub nice { |
488 | Sets (or gets in case the argument is missing) the description for this |
282 | $_[0]{prio} -= $_[1]; |
489 | coroutine. This is just a free-form string you can associate with a |
|
|
490 | coroutine. |
|
|
491 | |
|
|
492 | This method simply sets the C<< $coroutine->{desc} >> member to the given |
|
|
493 | string. You can modify this member directly if you wish. |
|
|
494 | |
|
|
495 | =cut |
|
|
496 | |
|
|
497 | sub desc { |
|
|
498 | my $old = $_[0]{desc}; |
|
|
499 | $_[0]{desc} = $_[1] if @_ > 1; |
|
|
500 | $old; |
283 | } |
501 | } |
284 | |
502 | |
285 | =back |
503 | =back |
286 | |
504 | |
|
|
505 | =head2 GLOBAL FUNCTIONS |
|
|
506 | |
|
|
507 | =over 4 |
|
|
508 | |
|
|
509 | =item Coro::nready |
|
|
510 | |
|
|
511 | Returns the number of coroutines that are currently in the ready state, |
|
|
512 | i.e. that can be switched to by calling C<schedule> directory or |
|
|
513 | indirectly. The value C<0> means that the only runnable coroutine is the |
|
|
514 | currently running one, so C<cede> would have no effect, and C<schedule> |
|
|
515 | would cause a deadlock unless there is an idle handler that wakes up some |
|
|
516 | coroutines. |
|
|
517 | |
|
|
518 | =item my $guard = Coro::guard { ... } |
|
|
519 | |
|
|
520 | This creates and returns a guard object. Nothing happens until the object |
|
|
521 | gets destroyed, in which case the codeblock given as argument will be |
|
|
522 | executed. This is useful to free locks or other resources in case of a |
|
|
523 | runtime error or when the coroutine gets canceled, as in both cases the |
|
|
524 | guard block will be executed. The guard object supports only one method, |
|
|
525 | C<< ->cancel >>, which will keep the codeblock from being executed. |
|
|
526 | |
|
|
527 | Example: set some flag and clear it again when the coroutine gets canceled |
|
|
528 | or the function returns: |
|
|
529 | |
|
|
530 | sub do_something { |
|
|
531 | my $guard = Coro::guard { $busy = 0 }; |
|
|
532 | $busy = 1; |
|
|
533 | |
|
|
534 | # do something that requires $busy to be true |
|
|
535 | } |
|
|
536 | |
|
|
537 | =cut |
|
|
538 | |
|
|
539 | sub guard(&) { |
|
|
540 | bless \(my $cb = $_[0]), "Coro::guard" |
|
|
541 | } |
|
|
542 | |
|
|
543 | sub Coro::guard::cancel { |
|
|
544 | ${$_[0]} = sub { }; |
|
|
545 | } |
|
|
546 | |
|
|
547 | sub Coro::guard::DESTROY { |
|
|
548 | ${$_[0]}->(); |
|
|
549 | } |
|
|
550 | |
|
|
551 | |
|
|
552 | =item unblock_sub { ... } |
|
|
553 | |
|
|
554 | This utility function takes a BLOCK or code reference and "unblocks" it, |
|
|
555 | returning a new coderef. Unblocking means that calling the new coderef |
|
|
556 | will return immediately without blocking, returning nothing, while the |
|
|
557 | original code ref will be called (with parameters) from within another |
|
|
558 | coroutine. |
|
|
559 | |
|
|
560 | The reason this function exists is that many event libraries (such as the |
|
|
561 | venerable L<Event|Event> module) are not coroutine-safe (a weaker form |
|
|
562 | of thread-safety). This means you must not block within event callbacks, |
|
|
563 | otherwise you might suffer from crashes or worse. The only event library |
|
|
564 | currently known that is safe to use without C<unblock_sub> is L<EV>. |
|
|
565 | |
|
|
566 | This function allows your callbacks to block by executing them in another |
|
|
567 | coroutine where it is safe to block. One example where blocking is handy |
|
|
568 | is when you use the L<Coro::AIO|Coro::AIO> functions to save results to |
|
|
569 | disk, for example. |
|
|
570 | |
|
|
571 | In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when |
|
|
572 | creating event callbacks that want to block. |
|
|
573 | |
|
|
574 | If your handler does not plan to block (e.g. simply sends a message to |
|
|
575 | another coroutine, or puts some other coroutine into the ready queue), |
|
|
576 | there is no reason to use C<unblock_sub>. |
|
|
577 | |
|
|
578 | Note that you also need to use C<unblock_sub> for any other callbacks that |
|
|
579 | are indirectly executed by any C-based event loop. For example, when you |
|
|
580 | use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it |
|
|
581 | provides callbacks that are the result of some event callback, then you |
|
|
582 | must not block either, or use C<unblock_sub>. |
|
|
583 | |
|
|
584 | =cut |
|
|
585 | |
|
|
586 | our @unblock_queue; |
|
|
587 | |
|
|
588 | # we create a special coro because we want to cede, |
|
|
589 | # to reduce pressure on the coro pool (because most callbacks |
|
|
590 | # return immediately and can be reused) and because we cannot cede |
|
|
591 | # inside an event callback. |
|
|
592 | our $unblock_scheduler = new Coro sub { |
|
|
593 | while () { |
|
|
594 | while (my $cb = pop @unblock_queue) { |
|
|
595 | &async_pool (@$cb); |
|
|
596 | |
|
|
597 | # for short-lived callbacks, this reduces pressure on the coro pool |
|
|
598 | # as the chance is very high that the async_poll coro will be back |
|
|
599 | # in the idle state when cede returns |
|
|
600 | cede; |
|
|
601 | } |
|
|
602 | schedule; # sleep well |
|
|
603 | } |
|
|
604 | }; |
|
|
605 | $unblock_scheduler->{desc} = "[unblock_sub scheduler]"; |
|
|
606 | |
|
|
607 | sub unblock_sub(&) { |
|
|
608 | my $cb = shift; |
|
|
609 | |
|
|
610 | sub { |
|
|
611 | unshift @unblock_queue, [$cb, @_]; |
|
|
612 | $unblock_scheduler->ready; |
|
|
613 | } |
|
|
614 | } |
|
|
615 | |
|
|
616 | =item $cb = Coro::rouse_cb |
|
|
617 | |
|
|
618 | Create and return a "rouse callback". That's a code reference that, when |
|
|
619 | called, will save its arguments and notify the owner coroutine of the |
|
|
620 | callback. |
|
|
621 | |
|
|
622 | See the next function. |
|
|
623 | |
|
|
624 | =item @args = Coro::rouse_wait [$cb] |
|
|
625 | |
|
|
626 | Wait for the specified rouse callback (or the last one tht was created in |
|
|
627 | this coroutine). |
|
|
628 | |
|
|
629 | As soon as the callback is invoked (or when the calback was invoked before |
|
|
630 | C<rouse_wait>), it will return a copy of the arguments originally passed |
|
|
631 | to the rouse callback. |
|
|
632 | |
|
|
633 | See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example. |
|
|
634 | |
|
|
635 | =back |
|
|
636 | |
287 | =cut |
637 | =cut |
288 | |
638 | |
289 | 1; |
639 | 1; |
290 | |
640 | |
|
|
641 | =head1 HOW TO WAIT FOR A CALLBACK |
|
|
642 | |
|
|
643 | It is very common for a coroutine to wait for some callback to be |
|
|
644 | called. This occurs naturally when you use coroutines in an otherwise |
|
|
645 | event-based program, or when you use event-based libraries. |
|
|
646 | |
|
|
647 | These typically register a callback for some event, and call that callback |
|
|
648 | when the event occured. In a coroutine, however, you typically want to |
|
|
649 | just wait for the event, simplyifying things. |
|
|
650 | |
|
|
651 | For example C<< AnyEvent->child >> registers a callback to be called when |
|
|
652 | a specific child has exited: |
|
|
653 | |
|
|
654 | my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... }); |
|
|
655 | |
|
|
656 | But from withina coroutine, you often just want to write this: |
|
|
657 | |
|
|
658 | my $status = wait_for_child $pid; |
|
|
659 | |
|
|
660 | Coro offers two functions specifically designed to make this easy, |
|
|
661 | C<Coro::rouse_cb> and C<Coro::rouse_wait>. |
|
|
662 | |
|
|
663 | The first function, C<rouse_cb>, generates and returns a callback that, |
|
|
664 | when invoked, will save it's arguments and notify the coroutine that |
|
|
665 | created the callback. |
|
|
666 | |
|
|
667 | The second function, C<rouse_wait>, waits for the callback to be called |
|
|
668 | (by calling C<schedule> to go to sleep) and returns the arguments |
|
|
669 | originally passed to the callback. |
|
|
670 | |
|
|
671 | Using these functions, it becomes easy to write the C<wait_for_child> |
|
|
672 | function mentioned above: |
|
|
673 | |
|
|
674 | sub wait_for_child($) { |
|
|
675 | my ($pid) = @_; |
|
|
676 | |
|
|
677 | my $watcher = AnyEvent->child (pid => $pid, cb => Coro::rouse_cb); |
|
|
678 | |
|
|
679 | my ($rpid, $rstatus) = Coro::rouse_wait; |
|
|
680 | $rstatus |
|
|
681 | } |
|
|
682 | |
|
|
683 | In the case where C<rouse_cb> and C<rouse_wait> are not flexible enough, |
|
|
684 | you can roll your own, using C<schedule>: |
|
|
685 | |
|
|
686 | sub wait_for_child($) { |
|
|
687 | my ($pid) = @_; |
|
|
688 | |
|
|
689 | # store the current coroutine in $current, |
|
|
690 | # and provide result variables for the closure passed to ->child |
|
|
691 | my $current = $Coro::current; |
|
|
692 | my ($done, $rstatus); |
|
|
693 | |
|
|
694 | # pass a closure to ->child |
|
|
695 | my $watcher = AnyEvent->child (pid => $pid, cb => sub { |
|
|
696 | $rstatus = $_[1]; # remember rstatus |
|
|
697 | $done = 1; # mark $rstatus as valud |
|
|
698 | }); |
|
|
699 | |
|
|
700 | # wait until the closure has been called |
|
|
701 | schedule while !$done; |
|
|
702 | |
|
|
703 | $rstatus |
|
|
704 | } |
|
|
705 | |
|
|
706 | |
291 | =head1 BUGS/LIMITATIONS |
707 | =head1 BUGS/LIMITATIONS |
292 | |
708 | |
293 | - you must make very sure that no coro is still active on global destruction. |
709 | =over 4 |
294 | very bad things might happen otherwise (usually segfaults). |
710 | |
295 | - this module is not thread-safe. You must only ever use this module from |
711 | =item fork with pthread backend |
|
|
712 | |
|
|
713 | When Coro is compiled using the pthread backend (which isn't recommended |
|
|
714 | but required on many BSDs as their libcs are completely broken), then |
|
|
715 | coroutines will not survive a fork. There is no known workaround except to |
|
|
716 | fix your libc and use a saner backend. |
|
|
717 | |
|
|
718 | =item perl process emulation ("threads") |
|
|
719 | |
|
|
720 | This module is not perl-pseudo-thread-safe. You should only ever use this |
296 | the same thread (this requirement might be loosened in the future to |
721 | module from the same thread (this requirement might be removed in the |
297 | allow per-thread schedulers, but Coro::State does not yet allow this). |
722 | future to allow per-thread schedulers, but Coro::State does not yet allow |
|
|
723 | this). I recommend disabling thread support and using processes, as having |
|
|
724 | the windows process emulation enabled under unix roughly halves perl |
|
|
725 | performance, even when not used. |
|
|
726 | |
|
|
727 | =item coroutine switching not signal safe |
|
|
728 | |
|
|
729 | You must not switch to another coroutine from within a signal handler |
|
|
730 | (only relevant with %SIG - most event libraries provide safe signals). |
|
|
731 | |
|
|
732 | That means you I<MUST NOT> call any function that might "block" the |
|
|
733 | current coroutine - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or |
|
|
734 | anything that calls those. Everything else, including calling C<ready>, |
|
|
735 | works. |
|
|
736 | |
|
|
737 | =back |
|
|
738 | |
298 | |
739 | |
299 | =head1 SEE ALSO |
740 | =head1 SEE ALSO |
300 | |
741 | |
301 | L<Coro::Channel>, L<Coro::Cont>, L<Coro::Specific>, L<Coro::Semaphore>, |
742 | Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>. |
302 | L<Coro::Signal>, L<Coro::State>, L<Coro::Event>, L<Coro::RWLock>, |
743 | |
303 | L<Coro::Handle>, L<Coro::Socket>. |
744 | Debugging: L<Coro::Debug>. |
|
|
745 | |
|
|
746 | Support/Utility: L<Coro::Specific>, L<Coro::Util>. |
|
|
747 | |
|
|
748 | Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>. |
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749 | |
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750 | IO/Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>. |
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751 | |
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752 | Compatibility: L<Coro::LWP>, L<Coro::BDB>, L<Coro::Storable>, L<Coro::Select>. |
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753 | |
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754 | XS API: L<Coro::MakeMaker>. |
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755 | |
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756 | Low level Configuration, Coroutine Environment: L<Coro::State>. |
304 | |
757 | |
305 | =head1 AUTHOR |
758 | =head1 AUTHOR |
306 | |
759 | |
307 | Marc Lehmann <pcg@goof.com> |
760 | Marc Lehmann <schmorp@schmorp.de> |
308 | http://www.goof.com/pcg/marc/ |
761 | http://home.schmorp.de/ |
309 | |
762 | |
310 | =cut |
763 | =cut |
311 | |
764 | |