1 | =head1 NAME |
1 | =head1 NAME |
2 | |
2 | |
3 | Coro - coroutine process abstraction |
3 | Coro - the only real threads in perl |
4 | |
4 | |
5 | =head1 SYNOPSIS |
5 | =head1 SYNOPSIS |
6 | |
6 | |
7 | use Coro; |
7 | use Coro; |
8 | |
8 | |
9 | async { |
9 | async { |
10 | # some asynchronous thread of execution |
10 | # some asynchronous thread of execution |
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11 | print "2\n"; |
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12 | cede; # yield back to main |
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13 | print "4\n"; |
11 | }; |
14 | }; |
12 | |
15 | print "1\n"; |
13 | # alternatively create an async coroutine like this: |
16 | cede; # yield to coro |
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 |
31 | For a tutorial-style introduction, please read the L<Coro::Intro> |
24 | to threads but don't run in parallel at the same time even on SMP |
32 | manpage. This manpage mainly contains reference information. |
25 | machines. The specific flavor of coroutine used in this module also |
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26 | guarantees you that it will not switch between coroutines unless |
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27 | necessary, at easily-identified points in your program, so locking and |
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28 | parallel access are rarely an issue, making coroutine programming much |
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29 | safer than threads programming. |
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30 | |
33 | |
31 | (Perl, however, does not natively support real threads but instead does a |
34 | This module collection manages continuations in general, most often in |
32 | very slow and memory-intensive emulation of processes using threads. This |
35 | the form of cooperative threads (also called coros, or simply "coro" |
33 | is a performance win on Windows machines, and a loss everywhere else). |
36 | in the documentation). They are similar to kernel threads but don't (in |
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37 | general) run in parallel at the same time even on SMP machines. The |
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38 | specific flavor of thread offered by this module also guarantees you that |
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39 | it will not switch between threads unless necessary, at easily-identified |
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40 | points in your program, so locking and parallel access are rarely an |
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41 | issue, making thread programming much safer and easier than using other |
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42 | thread models. |
34 | |
43 | |
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44 | Unlike the so-called "Perl threads" (which are not actually real threads |
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45 | but only the windows process emulation ported to unix, and as such act |
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46 | as processes), Coro provides a full shared address space, which makes |
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47 | communication between threads very easy. And Coro's threads are fast, |
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48 | too: disabling the Windows process emulation code in your perl and using |
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49 | Coro can easily result in a two to four times speed increase for your |
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50 | programs. A parallel matrix multiplication benchmark runs over 300 times |
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51 | faster on a single core than perl's pseudo-threads on a quad core using |
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52 | all four cores. |
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53 | |
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54 | Coro achieves that by supporting multiple running interpreters that share |
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55 | data, which is especially useful to code pseudo-parallel processes and |
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56 | for event-based programming, such as multiple HTTP-GET requests running |
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57 | concurrently. See L<Coro::AnyEvent> to learn more on how to integrate Coro |
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58 | into an event-based environment. |
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59 | |
35 | In this module, coroutines are defined as "callchain + lexical variables + |
60 | In this module, a thread is defined as "callchain + lexical variables + |
36 | @_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain, |
61 | some package variables + C stack), that is, a thread has its own callchain, |
37 | its own set of lexicals and its own set of perls most important global |
62 | its own set of lexicals and its own set of perls most important global |
38 | variables. |
63 | variables (see L<Coro::State> for more configuration and background info). |
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64 | |
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65 | See also the C<SEE ALSO> section at the end of this document - the Coro |
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66 | module family is quite large. |
39 | |
67 | |
40 | =cut |
68 | =cut |
41 | |
69 | |
42 | package Coro; |
70 | package Coro; |
43 | |
71 | |
44 | use strict; |
72 | use strict qw(vars subs); |
45 | no warnings "uninitialized"; |
73 | no warnings "uninitialized"; |
46 | |
74 | |
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75 | use Guard (); |
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76 | |
47 | use Coro::State; |
77 | use Coro::State; |
48 | |
78 | |
49 | use base qw(Coro::State Exporter); |
79 | use base qw(Coro::State Exporter); |
50 | |
80 | |
51 | our $idle; # idle handler |
81 | our $idle; # idle handler |
52 | our $main; # main coroutine |
82 | our $main; # main coro |
53 | our $current; # current coroutine |
83 | our $current; # current coro |
54 | |
84 | |
55 | our $VERSION = '4.02'; |
85 | our $VERSION = 5.132; |
56 | |
86 | |
57 | our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); |
87 | our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); |
58 | our %EXPORT_TAGS = ( |
88 | our %EXPORT_TAGS = ( |
59 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
89 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
60 | ); |
90 | ); |
61 | our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready)); |
91 | our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready)); |
62 | |
92 | |
63 | { |
93 | =head1 GLOBAL VARIABLES |
64 | my @async; |
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65 | my $init; |
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66 | |
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67 | # this way of handling attributes simply is NOT scalable ;() |
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68 | sub import { |
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69 | no strict 'refs'; |
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70 | |
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71 | Coro->export_to_level (1, @_); |
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72 | |
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73 | my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE}; |
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74 | *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub { |
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75 | my ($package, $ref) = (shift, shift); |
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76 | my @attrs; |
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77 | for (@_) { |
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78 | if ($_ eq "Coro") { |
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79 | push @async, $ref; |
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80 | unless ($init++) { |
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81 | eval q{ |
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82 | sub INIT { |
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83 | &async(pop @async) while @async; |
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84 | } |
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85 | }; |
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86 | } |
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87 | } else { |
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88 | push @attrs, $_; |
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89 | } |
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90 | } |
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91 | return $old ? $old->($package, $ref, @attrs) : @attrs; |
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92 | }; |
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93 | } |
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94 | |
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95 | } |
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96 | |
94 | |
97 | =over 4 |
95 | =over 4 |
98 | |
96 | |
99 | =item $main |
97 | =item $Coro::main |
100 | |
98 | |
101 | This coroutine represents the main program. |
99 | This variable stores the Coro object that represents the main |
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100 | program. While you cna C<ready> it and do most other things you can do to |
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101 | coro, it is mainly useful to compare again C<$Coro::current>, to see |
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102 | whether you are running in the main program or not. |
102 | |
103 | |
103 | =cut |
104 | =cut |
104 | |
105 | |
105 | $main = new Coro; |
106 | # $main is now being initialised by Coro::State |
106 | |
107 | |
107 | =item $current (or as function: current) |
108 | =item $Coro::current |
108 | |
109 | |
109 | The current coroutine (the last coroutine switched to). The initial value |
110 | The Coro object representing the current coro (the last |
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111 | coro that the Coro scheduler switched to). The initial value is |
110 | is C<$main> (of course). |
112 | C<$Coro::main> (of course). |
111 | |
113 | |
112 | This variable is B<strictly> I<read-only>. It is provided for performance |
114 | This variable is B<strictly> I<read-only>. You can take copies of the |
113 | reasons. If performance is not essential you are encouraged to use the |
115 | value stored in it and use it as any other Coro object, but you must |
114 | C<Coro::current> function instead. |
116 | not otherwise modify the variable itself. |
115 | |
117 | |
116 | =cut |
118 | =cut |
117 | |
119 | |
118 | $main->{desc} = "[main::]"; |
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119 | |
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120 | # maybe some other module used Coro::Specific before... |
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121 | $main->{_specific} = $current->{_specific} |
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122 | if $current; |
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123 | |
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124 | _set_current $main; |
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125 | |
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126 | sub current() { $current } |
120 | sub current() { $current } # [DEPRECATED] |
127 | |
121 | |
128 | =item $idle |
122 | =item $Coro::idle |
129 | |
123 | |
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124 | This variable is mainly useful to integrate Coro into event loops. It is |
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125 | usually better to rely on L<Coro::AnyEvent> or L<Coro::EV>, as this is |
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126 | pretty low-level functionality. |
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127 | |
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128 | This variable stores either a Coro object or a callback. |
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129 | |
130 | A callback that is called whenever the scheduler finds no ready coroutines |
130 | If it is a callback, the it is called whenever the scheduler finds no |
131 | to run. The default implementation prints "FATAL: deadlock detected" and |
131 | ready coros to run. The default implementation prints "FATAL: |
132 | exits, because the program has no other way to continue. |
132 | deadlock detected" and exits, because the program has no other way to |
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133 | continue. |
133 | |
134 | |
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135 | If it is a coro object, then this object will be readied (without |
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136 | invoking any ready hooks, however) when the scheduler finds no other ready |
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137 | coros to run. |
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138 | |
134 | This hook is overwritten by modules such as C<Coro::Timer> and |
139 | This hook is overwritten by modules such as C<Coro::EV> and |
135 | C<Coro::Event> to wait on an external event that hopefully wake up a |
140 | C<Coro::AnyEvent> to wait on an external event that hopefully wake up a |
136 | coroutine so the scheduler can run it. |
141 | coro so the scheduler can run it. |
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142 | |
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143 | Note that the callback I<must not>, under any circumstances, block |
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144 | the current coro. Normally, this is achieved by having an "idle |
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145 | coro" that calls the event loop and then blocks again, and then |
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146 | readying that coro in the idle handler, or by simply placing the idle |
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147 | coro in this variable. |
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148 | |
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149 | See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this |
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150 | technique. |
137 | |
151 | |
138 | Please note that if your callback recursively invokes perl (e.g. for event |
152 | Please note that if your callback recursively invokes perl (e.g. for event |
139 | handlers), then it must be prepared to be called recursively. |
153 | handlers), then it must be prepared to be called recursively itself. |
140 | |
154 | |
141 | =cut |
155 | =cut |
142 | |
156 | |
143 | $idle = sub { |
157 | $idle = sub { |
144 | require Carp; |
158 | require Carp; |
145 | Carp::croak ("FATAL: deadlock detected"); |
159 | Carp::croak ("FATAL: deadlock detected"); |
146 | }; |
160 | }; |
147 | |
161 | |
148 | sub _cancel { |
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149 | my ($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 | } |
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159 | |
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160 | # this coroutine is necessary because a coroutine |
162 | # this coro is necessary because a coro |
161 | # cannot destroy itself. |
163 | # cannot destroy itself. |
162 | my @destroy; |
164 | our @destroy; |
163 | my $manager; |
165 | our $manager; |
164 | |
166 | |
165 | $manager = new Coro sub { |
167 | $manager = new Coro sub { |
166 | while () { |
168 | while () { |
167 | (shift @destroy)->_cancel |
169 | Coro::State::cancel shift @destroy |
168 | while @destroy; |
170 | while @destroy; |
169 | |
171 | |
170 | &schedule; |
172 | &schedule; |
171 | } |
173 | } |
172 | }; |
174 | }; |
173 | $manager->desc ("[coro manager]"); |
175 | $manager->{desc} = "[coro manager]"; |
174 | $manager->prio (PRIO_MAX); |
176 | $manager->prio (PRIO_MAX); |
175 | |
177 | |
176 | # static methods. not really. |
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177 | |
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178 | =back |
178 | =back |
179 | |
179 | |
180 | =head2 STATIC METHODS |
180 | =head1 SIMPLE CORO CREATION |
181 | |
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182 | Static methods are actually functions that operate on the current coroutine only. |
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183 | |
181 | |
184 | =over 4 |
182 | =over 4 |
185 | |
183 | |
186 | =item async { ... } [@args...] |
184 | =item async { ... } [@args...] |
187 | |
185 | |
188 | Create a new asynchronous coroutine and return it's coroutine object |
186 | Create a new coro and return its Coro object (usually |
189 | (usually unused). When the sub returns the new coroutine is automatically |
187 | unused). The coro will be put into the ready queue, so |
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188 | it will start running automatically on the next scheduler run. |
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189 | |
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190 | The first argument is a codeblock/closure that should be executed in the |
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191 | coro. When it returns argument returns the coro is automatically |
190 | terminated. |
192 | terminated. |
191 | |
193 | |
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194 | The remaining arguments are passed as arguments to the closure. |
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195 | |
192 | See the C<Coro::State::new> constructor for info about the coroutine |
196 | See the C<Coro::State::new> constructor for info about the coro |
193 | environment. |
197 | environment in which coro are executed. |
194 | |
198 | |
195 | Calling C<exit> in a coroutine will do the same as calling exit outside |
199 | Calling C<exit> in a coro will do the same as calling exit outside |
196 | the coroutine. Likewise, when the coroutine dies, the program will exit, |
200 | the coro. Likewise, when the coro dies, the program will exit, |
197 | just as it would in the main program. |
201 | just as it would in the main program. |
198 | |
202 | |
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203 | If you do not want that, you can provide a default C<die> handler, or |
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204 | simply avoid dieing (by use of C<eval>). |
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205 | |
199 | # create a new coroutine that just prints its arguments |
206 | Example: Create a new coro that just prints its arguments. |
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207 | |
200 | async { |
208 | async { |
201 | print "@_\n"; |
209 | print "@_\n"; |
202 | } 1,2,3,4; |
210 | } 1,2,3,4; |
203 | |
211 | |
204 | =cut |
212 | =cut |
… | |
… | |
209 | $coro |
217 | $coro |
210 | } |
218 | } |
211 | |
219 | |
212 | =item async_pool { ... } [@args...] |
220 | =item async_pool { ... } [@args...] |
213 | |
221 | |
214 | Similar to C<async>, but uses a coroutine pool, so you should not call |
222 | Similar to C<async>, but uses a coro pool, so you should not call |
215 | terminate or join (although you are allowed to), and you get a coroutine |
223 | terminate or join on it (although you are allowed to), and you get a |
216 | that might have executed other code already (which can be good or bad :). |
224 | coro that might have executed other code already (which can be good |
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225 | or bad :). |
217 | |
226 | |
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227 | On the plus side, this function is about twice as fast as creating (and |
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228 | destroying) a completely new coro, so if you need a lot of generic |
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229 | coros in quick successsion, use C<async_pool>, not C<async>. |
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230 | |
218 | Also, the block is executed in an C<eval> context and a warning will be |
231 | The code block is executed in an C<eval> context and a warning will be |
219 | issued in case of an exception instead of terminating the program, as |
232 | issued in case of an exception instead of terminating the program, as |
220 | C<async> does. As the coroutine is being reused, stuff like C<on_destroy> |
233 | C<async> does. As the coro is being reused, stuff like C<on_destroy> |
221 | will not work in the expected way, unless you call terminate or cancel, |
234 | will not work in the expected way, unless you call terminate or cancel, |
222 | which somehow defeats the purpose of pooling. |
235 | which somehow defeats the purpose of pooling (but is fine in the |
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236 | exceptional case). |
223 | |
237 | |
224 | The priority will be reset to C<0> after each job, tracing will be |
238 | The priority will be reset to C<0> after each run, tracing will be |
225 | disabled, the description will be reset and the default output filehandle |
239 | disabled, the description will be reset and the default output filehandle |
226 | gets restored, so you can change alkl these. Otherwise the coroutine will |
240 | gets restored, so you can change all these. Otherwise the coro will |
227 | be re-used "as-is": most notably if you change other per-coroutine global |
241 | be re-used "as-is": most notably if you change other per-coro global |
228 | stuff such as C<$/> you need to revert that change, which is most simply |
242 | stuff such as C<$/> you I<must needs> revert that change, which is most |
229 | done by using local as in C< local $/ >. |
243 | simply done by using local as in: C<< local $/ >>. |
230 | |
244 | |
231 | The pool size is limited to 8 idle coroutines (this can be adjusted by |
245 | The idle pool size is limited to C<8> idle coros (this can be |
232 | changing $Coro::POOL_SIZE), and there can be as many non-idle coros as |
246 | adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle |
233 | required. |
247 | coros as required. |
234 | |
248 | |
235 | If you are concerned about pooled coroutines growing a lot because a |
249 | If you are concerned about pooled coros growing a lot because a |
236 | single C<async_pool> used a lot of stackspace you can e.g. C<async_pool |
250 | single C<async_pool> used a lot of stackspace you can e.g. C<async_pool |
237 | { terminate }> once per second or so to slowly replenish the pool. In |
251 | { terminate }> once per second or so to slowly replenish the pool. In |
238 | addition to that, when the stacks used by a handler grows larger than 16kb |
252 | addition to that, when the stacks used by a handler grows larger than 32kb |
239 | (adjustable with $Coro::POOL_RSS) it will also exit. |
253 | (adjustable via $Coro::POOL_RSS) it will also be destroyed. |
240 | |
254 | |
241 | =cut |
255 | =cut |
242 | |
256 | |
243 | our $POOL_SIZE = 8; |
257 | our $POOL_SIZE = 8; |
244 | our $POOL_RSS = 16 * 1024; |
258 | our $POOL_RSS = 32 * 1024; |
245 | our @async_pool; |
259 | our @async_pool; |
246 | |
260 | |
247 | sub pool_handler { |
261 | sub pool_handler { |
248 | my $cb; |
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249 | |
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250 | while () { |
262 | while () { |
251 | eval { |
263 | eval { |
252 | while () { |
264 | &{&_pool_handler} while 1; |
253 | _pool_1 $cb; |
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254 | &$cb; |
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255 | _pool_2 $cb; |
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256 | &schedule; |
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257 | } |
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258 | }; |
265 | }; |
259 | |
266 | |
260 | last if $@ eq "\3terminate\2\n"; |
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261 | warn $@ if $@; |
267 | warn $@ if $@; |
262 | } |
268 | } |
263 | } |
269 | } |
264 | |
270 | |
265 | sub async_pool(&@) { |
271 | =back |
266 | # this is also inlined into the unlock_scheduler |
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267 | my $coro = (pop @async_pool) || new Coro \&pool_handler; |
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268 | |
272 | |
269 | $coro->{_invoke} = [@_]; |
273 | =head1 STATIC METHODS |
270 | $coro->ready; |
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271 | |
274 | |
272 | $coro |
275 | Static methods are actually functions that implicitly operate on the |
273 | } |
276 | current coro. |
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277 | |
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278 | =over 4 |
274 | |
279 | |
275 | =item schedule |
280 | =item schedule |
276 | |
281 | |
277 | Calls the scheduler. Please note that the current coroutine will not be put |
282 | Calls the scheduler. The scheduler will find the next coro that is |
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283 | to be run from the ready queue and switches to it. The next coro |
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284 | to be run is simply the one with the highest priority that is longest |
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285 | in its ready queue. If there is no coro ready, it will clal the |
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286 | C<$Coro::idle> hook. |
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287 | |
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288 | Please note that the current coro will I<not> be put into the ready |
278 | into the ready queue, so calling this function usually means you will |
289 | queue, so calling this function usually means you will never be called |
279 | never be called again unless something else (e.g. an event handler) calls |
290 | again unless something else (e.g. an event handler) calls C<< ->ready >>, |
280 | ready. |
291 | thus waking you up. |
281 | |
292 | |
282 | The canonical way to wait on external events is this: |
293 | This makes C<schedule> I<the> generic method to use to block the current |
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294 | coro and wait for events: first you remember the current coro in |
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295 | a variable, then arrange for some callback of yours to call C<< ->ready |
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296 | >> on that once some event happens, and last you call C<schedule> to put |
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297 | yourself to sleep. Note that a lot of things can wake your coro up, |
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298 | so you need to check whether the event indeed happened, e.g. by storing the |
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299 | status in a variable. |
283 | |
300 | |
284 | { |
301 | See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks. |
285 | # remember current coroutine |
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286 | my $current = $Coro::current; |
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287 | |
302 | |
288 | # register a hypothetical event handler |
303 | =item cede |
289 | on_event_invoke sub { |
304 | |
290 | # wake up sleeping coroutine |
305 | "Cede" to other coros. This function puts the current coro into |
291 | $current->ready; |
306 | the ready queue and calls C<schedule>, which has the effect of giving |
292 | undef $current; |
307 | up the current "timeslice" to other coros of the same or higher |
|
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308 | priority. Once your coro gets its turn again it will automatically be |
|
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309 | resumed. |
|
|
310 | |
|
|
311 | This function is often called C<yield> in other languages. |
|
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312 | |
|
|
313 | =item Coro::cede_notself |
|
|
314 | |
|
|
315 | Works like cede, but is not exported by default and will cede to I<any> |
|
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316 | coro, regardless of priority. This is useful sometimes to ensure |
|
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317 | progress is made. |
|
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318 | |
|
|
319 | =item terminate [arg...] |
|
|
320 | |
|
|
321 | Terminates the current coro with the given status values (see L<cancel>). |
|
|
322 | |
|
|
323 | =item Coro::on_enter BLOCK, Coro::on_leave BLOCK |
|
|
324 | |
|
|
325 | These function install enter and leave winders in the current scope. The |
|
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326 | enter block will be executed when on_enter is called and whenever the |
|
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327 | current coro is re-entered by the scheduler, while the leave block is |
|
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328 | executed whenever the current coro is blocked by the scheduler, and |
|
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329 | also when the containing scope is exited (by whatever means, be it exit, |
|
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330 | die, last etc.). |
|
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331 | |
|
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332 | I<Neither invoking the scheduler, nor exceptions, are allowed within those |
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333 | BLOCKs>. That means: do not even think about calling C<die> without an |
|
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334 | eval, and do not even think of entering the scheduler in any way. |
|
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335 | |
|
|
336 | Since both BLOCKs are tied to the current scope, they will automatically |
|
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337 | be removed when the current scope exits. |
|
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338 | |
|
|
339 | These functions implement the same concept as C<dynamic-wind> in scheme |
|
|
340 | does, and are useful when you want to localise some resource to a specific |
|
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341 | coro. |
|
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342 | |
|
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343 | They slow down thread switching considerably for coros that use them |
|
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344 | (about 40% for a BLOCK with a single assignment, so thread switching is |
|
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345 | still reasonably fast if the handlers are fast). |
|
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346 | |
|
|
347 | These functions are best understood by an example: The following function |
|
|
348 | will change the current timezone to "Antarctica/South_Pole", which |
|
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349 | requires a call to C<tzset>, but by using C<on_enter> and C<on_leave>, |
|
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350 | which remember/change the current timezone and restore the previous |
|
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351 | value, respectively, the timezone is only changed for the coro that |
|
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352 | installed those handlers. |
|
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353 | |
|
|
354 | use POSIX qw(tzset); |
|
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355 | |
|
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356 | async { |
|
|
357 | my $old_tz; # store outside TZ value here |
|
|
358 | |
|
|
359 | Coro::on_enter { |
|
|
360 | $old_tz = $ENV{TZ}; # remember the old value |
|
|
361 | |
|
|
362 | $ENV{TZ} = "Antarctica/South_Pole"; |
|
|
363 | tzset; # enable new value |
293 | }; |
364 | }; |
294 | |
365 | |
295 | # call schedule until event occurred. |
366 | Coro::on_leave { |
296 | # in case we are woken up for other reasons |
367 | $ENV{TZ} = $old_tz; |
297 | # (current still defined), loop. |
368 | tzset; # restore old value |
298 | Coro::schedule while $current; |
369 | }; |
|
|
370 | |
|
|
371 | # at this place, the timezone is Antarctica/South_Pole, |
|
|
372 | # without disturbing the TZ of any other coro. |
299 | } |
373 | }; |
300 | |
374 | |
301 | =item cede |
375 | This can be used to localise about any resource (locale, uid, current |
302 | |
376 | working directory etc.) to a block, despite the existance of other |
303 | "Cede" to other coroutines. This function puts the current coroutine into the |
377 | coros. |
304 | ready queue and calls C<schedule>, which has the effect of giving up the |
|
|
305 | current "timeslice" to other coroutines of the same or higher priority. |
|
|
306 | |
|
|
307 | Returns true if at least one coroutine switch has happened. |
|
|
308 | |
|
|
309 | =item Coro::cede_notself |
|
|
310 | |
|
|
311 | Works like cede, but is not exported by default and will cede to any |
|
|
312 | coroutine, regardless of priority, once. |
|
|
313 | |
|
|
314 | Returns true if at least one coroutine switch has happened. |
|
|
315 | |
|
|
316 | =item terminate [arg...] |
|
|
317 | |
|
|
318 | Terminates the current coroutine with the given status values (see L<cancel>). |
|
|
319 | |
378 | |
320 | =item killall |
379 | =item killall |
321 | |
380 | |
322 | Kills/terminates/cancels all coroutines except the currently running |
381 | Kills/terminates/cancels all coros except the currently running one. |
323 | one. This is useful after a fork, either in the child or the parent, as |
|
|
324 | usually only one of them should inherit the running coroutines. |
|
|
325 | |
382 | |
326 | =cut |
383 | Note that while this will try to free some of the main interpreter |
|
|
384 | resources if the calling coro isn't the main coro, but one |
|
|
385 | cannot free all of them, so if a coro that is not the main coro |
|
|
386 | calls this function, there will be some one-time resource leak. |
327 | |
387 | |
328 | sub terminate { |
388 | =cut |
329 | $current->cancel (@_); |
|
|
330 | } |
|
|
331 | |
389 | |
332 | sub killall { |
390 | sub killall { |
333 | for (Coro::State::list) { |
391 | for (Coro::State::list) { |
334 | $_->cancel |
392 | $_->cancel |
335 | if $_ != $current && UNIVERSAL::isa $_, "Coro"; |
393 | if $_ != $current && UNIVERSAL::isa $_, "Coro"; |
336 | } |
394 | } |
337 | } |
395 | } |
338 | |
396 | |
339 | =back |
397 | =back |
340 | |
398 | |
341 | # dynamic methods |
|
|
342 | |
|
|
343 | =head2 COROUTINE METHODS |
399 | =head1 CORO OBJECT METHODS |
344 | |
400 | |
345 | These are the methods you can call on coroutine objects. |
401 | These are the methods you can call on coro objects (or to create |
|
|
402 | them). |
346 | |
403 | |
347 | =over 4 |
404 | =over 4 |
348 | |
405 | |
349 | =item new Coro \&sub [, @args...] |
406 | =item new Coro \&sub [, @args...] |
350 | |
407 | |
351 | Create a new coroutine and return it. When the sub returns the coroutine |
408 | Create a new coro and return it. When the sub returns, the coro |
352 | automatically terminates as if C<terminate> with the returned values were |
409 | automatically terminates as if C<terminate> with the returned values were |
353 | called. To make the coroutine run you must first put it into the ready queue |
410 | called. To make the coro run you must first put it into the ready |
354 | by calling the ready method. |
411 | queue by calling the ready method. |
355 | |
412 | |
356 | See C<async> and C<Coro::State::new> for additional info about the |
413 | See C<async> and C<Coro::State::new> for additional info about the |
357 | coroutine environment. |
414 | coro environment. |
358 | |
415 | |
359 | =cut |
416 | =cut |
360 | |
417 | |
361 | sub _run_coro { |
418 | sub _coro_run { |
362 | terminate &{+shift}; |
419 | terminate &{+shift}; |
363 | } |
420 | } |
364 | |
421 | |
365 | sub new { |
|
|
366 | my $class = shift; |
|
|
367 | |
|
|
368 | $class->SUPER::new (\&_run_coro, @_) |
|
|
369 | } |
|
|
370 | |
|
|
371 | =item $success = $coroutine->ready |
422 | =item $success = $coro->ready |
372 | |
423 | |
373 | Put the given coroutine into the ready queue (according to it's priority) |
424 | Put the given coro into the end of its ready queue (there is one |
374 | and return true. If the coroutine is already in the ready queue, do nothing |
425 | queue for each priority) and return true. If the coro is already in |
375 | and return false. |
426 | the ready queue, do nothing and return false. |
376 | |
427 | |
|
|
428 | This ensures that the scheduler will resume this coro automatically |
|
|
429 | once all the coro of higher priority and all coro of the same |
|
|
430 | priority that were put into the ready queue earlier have been resumed. |
|
|
431 | |
|
|
432 | =item $coro->suspend |
|
|
433 | |
|
|
434 | Suspends the specified coro. A suspended coro works just like any other |
|
|
435 | coro, except that the scheduler will not select a suspended coro for |
|
|
436 | execution. |
|
|
437 | |
|
|
438 | Suspending a coro can be useful when you want to keep the coro from |
|
|
439 | running, but you don't want to destroy it, or when you want to temporarily |
|
|
440 | freeze a coro (e.g. for debugging) to resume it later. |
|
|
441 | |
|
|
442 | A scenario for the former would be to suspend all (other) coros after a |
|
|
443 | fork and keep them alive, so their destructors aren't called, but new |
|
|
444 | coros can be created. |
|
|
445 | |
|
|
446 | =item $coro->resume |
|
|
447 | |
|
|
448 | If the specified coro was suspended, it will be resumed. Note that when |
|
|
449 | the coro was in the ready queue when it was suspended, it might have been |
|
|
450 | unreadied by the scheduler, so an activation might have been lost. |
|
|
451 | |
|
|
452 | To avoid this, it is best to put a suspended coro into the ready queue |
|
|
453 | unconditionally, as every synchronisation mechanism must protect itself |
|
|
454 | against spurious wakeups, and the one in the Coro family certainly do |
|
|
455 | that. |
|
|
456 | |
377 | =item $is_ready = $coroutine->is_ready |
457 | =item $is_ready = $coro->is_ready |
378 | |
458 | |
379 | Return wether the coroutine is currently the ready queue or not, |
459 | Returns true iff the Coro object is in the ready queue. Unless the Coro |
|
|
460 | object gets destroyed, it will eventually be scheduled by the scheduler. |
380 | |
461 | |
|
|
462 | =item $is_running = $coro->is_running |
|
|
463 | |
|
|
464 | Returns true iff the Coro object is currently running. Only one Coro object |
|
|
465 | can ever be in the running state (but it currently is possible to have |
|
|
466 | multiple running Coro::States). |
|
|
467 | |
|
|
468 | =item $is_suspended = $coro->is_suspended |
|
|
469 | |
|
|
470 | Returns true iff this Coro object has been suspended. Suspended Coros will |
|
|
471 | not ever be scheduled. |
|
|
472 | |
381 | =item $coroutine->cancel (arg...) |
473 | =item $coro->cancel (arg...) |
382 | |
474 | |
383 | Terminates the given coroutine and makes it return the given arguments as |
475 | Terminates the given Coro and makes it return the given arguments as |
384 | status (default: the empty list). Never returns if the coroutine is the |
476 | status (default: the empty list). Never returns if the Coro is the |
385 | current coroutine. |
477 | current Coro. |
386 | |
478 | |
387 | =cut |
479 | =cut |
388 | |
480 | |
389 | sub cancel { |
481 | sub cancel { |
390 | my $self = shift; |
482 | my $self = shift; |
391 | $self->{_status} = [@_]; |
|
|
392 | |
483 | |
393 | if ($current == $self) { |
484 | if ($current == $self) { |
394 | push @destroy, $self; |
485 | terminate @_; |
395 | $manager->ready; |
|
|
396 | &schedule while 1; |
|
|
397 | } else { |
486 | } else { |
398 | $self->_cancel; |
487 | $self->{_status} = [@_]; |
|
|
488 | Coro::State::cancel $self; |
399 | } |
489 | } |
400 | } |
490 | } |
401 | |
491 | |
|
|
492 | =item $coro->schedule_to |
|
|
493 | |
|
|
494 | Puts the current coro to sleep (like C<Coro::schedule>), but instead |
|
|
495 | of continuing with the next coro from the ready queue, always switch to |
|
|
496 | the given coro object (regardless of priority etc.). The readyness |
|
|
497 | state of that coro isn't changed. |
|
|
498 | |
|
|
499 | This is an advanced method for special cases - I'd love to hear about any |
|
|
500 | uses for this one. |
|
|
501 | |
|
|
502 | =item $coro->cede_to |
|
|
503 | |
|
|
504 | Like C<schedule_to>, but puts the current coro into the ready |
|
|
505 | queue. This has the effect of temporarily switching to the given |
|
|
506 | coro, and continuing some time later. |
|
|
507 | |
|
|
508 | This is an advanced method for special cases - I'd love to hear about any |
|
|
509 | uses for this one. |
|
|
510 | |
|
|
511 | =item $coro->throw ([$scalar]) |
|
|
512 | |
|
|
513 | If C<$throw> is specified and defined, it will be thrown as an exception |
|
|
514 | inside the coro at the next convenient point in time. Otherwise |
|
|
515 | clears the exception object. |
|
|
516 | |
|
|
517 | Coro will check for the exception each time a schedule-like-function |
|
|
518 | returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down |
|
|
519 | >>, C<< Coro::Handle->readable >> and so on. Most of these functions |
|
|
520 | detect this case and return early in case an exception is pending. |
|
|
521 | |
|
|
522 | The exception object will be thrown "as is" with the specified scalar in |
|
|
523 | C<$@>, i.e. if it is a string, no line number or newline will be appended |
|
|
524 | (unlike with C<die>). |
|
|
525 | |
|
|
526 | This can be used as a softer means than C<cancel> to ask a coro to |
|
|
527 | end itself, although there is no guarantee that the exception will lead to |
|
|
528 | termination, and if the exception isn't caught it might well end the whole |
|
|
529 | program. |
|
|
530 | |
|
|
531 | You might also think of C<throw> as being the moral equivalent of |
|
|
532 | C<kill>ing a coro with a signal (in this case, a scalar). |
|
|
533 | |
402 | =item $coroutine->join |
534 | =item $coro->join |
403 | |
535 | |
404 | Wait until the coroutine terminates and return any values given to the |
536 | Wait until the coro terminates and return any values given to the |
405 | C<terminate> or C<cancel> functions. C<join> can be called concurrently |
537 | C<terminate> or C<cancel> functions. C<join> can be called concurrently |
406 | from multiple coroutines. |
538 | from multiple coro, and all will be resumed and given the status |
|
|
539 | return once the C<$coro> terminates. |
407 | |
540 | |
408 | =cut |
541 | =cut |
409 | |
542 | |
410 | sub join { |
543 | sub join { |
411 | my $self = shift; |
544 | my $self = shift; |
… | |
… | |
422 | } |
555 | } |
423 | |
556 | |
424 | wantarray ? @{$self->{_status}} : $self->{_status}[0]; |
557 | wantarray ? @{$self->{_status}} : $self->{_status}[0]; |
425 | } |
558 | } |
426 | |
559 | |
427 | =item $coroutine->on_destroy (\&cb) |
560 | =item $coro->on_destroy (\&cb) |
428 | |
561 | |
429 | Registers a callback that is called when this coroutine gets destroyed, |
562 | Registers a callback that is called when this coro gets destroyed, |
430 | but before it is joined. The callback gets passed the terminate arguments, |
563 | but before it is joined. The callback gets passed the terminate arguments, |
431 | if any. |
564 | if any, and I<must not> die, under any circumstances. |
432 | |
565 | |
433 | =cut |
566 | =cut |
434 | |
567 | |
435 | sub on_destroy { |
568 | sub on_destroy { |
436 | my ($self, $cb) = @_; |
569 | my ($self, $cb) = @_; |
437 | |
570 | |
438 | push @{ $self->{_on_destroy} }, $cb; |
571 | push @{ $self->{_on_destroy} }, $cb; |
439 | } |
572 | } |
440 | |
573 | |
441 | =item $oldprio = $coroutine->prio ($newprio) |
574 | =item $oldprio = $coro->prio ($newprio) |
442 | |
575 | |
443 | Sets (or gets, if the argument is missing) the priority of the |
576 | Sets (or gets, if the argument is missing) the priority of the |
444 | coroutine. Higher priority coroutines get run before lower priority |
577 | coro. Higher priority coro get run before lower priority |
445 | coroutines. Priorities are small signed integers (currently -4 .. +3), |
578 | coro. Priorities are small signed integers (currently -4 .. +3), |
446 | that you can refer to using PRIO_xxx constants (use the import tag :prio |
579 | that you can refer to using PRIO_xxx constants (use the import tag :prio |
447 | to get then): |
580 | to get then): |
448 | |
581 | |
449 | PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN |
582 | PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN |
450 | 3 > 1 > 0 > -1 > -3 > -4 |
583 | 3 > 1 > 0 > -1 > -3 > -4 |
451 | |
584 | |
452 | # set priority to HIGH |
585 | # set priority to HIGH |
453 | current->prio(PRIO_HIGH); |
586 | current->prio (PRIO_HIGH); |
454 | |
587 | |
455 | The idle coroutine ($Coro::idle) always has a lower priority than any |
588 | The idle coro ($Coro::idle) always has a lower priority than any |
456 | existing coroutine. |
589 | existing coro. |
457 | |
590 | |
458 | Changing the priority of the current coroutine will take effect immediately, |
591 | Changing the priority of the current coro will take effect immediately, |
459 | but changing the priority of coroutines in the ready queue (but not |
592 | but changing the priority of coro in the ready queue (but not |
460 | running) will only take effect after the next schedule (of that |
593 | running) will only take effect after the next schedule (of that |
461 | coroutine). This is a bug that will be fixed in some future version. |
594 | coro). This is a bug that will be fixed in some future version. |
462 | |
595 | |
463 | =item $newprio = $coroutine->nice ($change) |
596 | =item $newprio = $coro->nice ($change) |
464 | |
597 | |
465 | Similar to C<prio>, but subtract the given value from the priority (i.e. |
598 | Similar to C<prio>, but subtract the given value from the priority (i.e. |
466 | higher values mean lower priority, just as in unix). |
599 | higher values mean lower priority, just as in unix). |
467 | |
600 | |
468 | =item $olddesc = $coroutine->desc ($newdesc) |
601 | =item $olddesc = $coro->desc ($newdesc) |
469 | |
602 | |
470 | Sets (or gets in case the argument is missing) the description for this |
603 | Sets (or gets in case the argument is missing) the description for this |
471 | coroutine. This is just a free-form string you can associate with a coroutine. |
604 | coro. This is just a free-form string you can associate with a |
|
|
605 | coro. |
472 | |
606 | |
473 | This method simply sets the C<< $coroutine->{desc} >> member to the given string. You |
607 | This method simply sets the C<< $coro->{desc} >> member to the given |
474 | can modify this member directly if you wish. |
608 | string. You can modify this member directly if you wish. |
475 | |
|
|
476 | =item $coroutine->throw ([$scalar]) |
|
|
477 | |
|
|
478 | If C<$throw> is specified and defined, it will be thrown as an exception |
|
|
479 | inside the coroutine at the next convinient point in time (usually after |
|
|
480 | it gains control at the next schedule/transfer/cede). Otherwise clears the |
|
|
481 | exception object. |
|
|
482 | |
|
|
483 | The exception object will be thrown "as is" with the specified scalar in |
|
|
484 | C<$@>, i.e. if it is a string, no line number or newline will be appended |
|
|
485 | (unlike with C<die>). |
|
|
486 | |
|
|
487 | This can be used as a softer means than C<cancel> to ask a coroutine to |
|
|
488 | end itself, although there is no guarentee that the exception will lead to |
|
|
489 | termination, and if the exception isn't caught it might well end the whole |
|
|
490 | program. |
|
|
491 | |
609 | |
492 | =cut |
610 | =cut |
493 | |
611 | |
494 | sub desc { |
612 | sub desc { |
495 | my $old = $_[0]{desc}; |
613 | my $old = $_[0]{desc}; |
496 | $_[0]{desc} = $_[1] if @_ > 1; |
614 | $_[0]{desc} = $_[1] if @_ > 1; |
497 | $old; |
615 | $old; |
498 | } |
616 | } |
499 | |
617 | |
|
|
618 | sub transfer { |
|
|
619 | require Carp; |
|
|
620 | Carp::croak ("You must not call ->transfer on Coro objects. Use Coro::State objects or the ->schedule_to method. Caught"); |
|
|
621 | } |
|
|
622 | |
500 | =back |
623 | =back |
501 | |
624 | |
502 | =head2 GLOBAL FUNCTIONS |
625 | =head1 GLOBAL FUNCTIONS |
503 | |
626 | |
504 | =over 4 |
627 | =over 4 |
505 | |
628 | |
506 | =item Coro::nready |
629 | =item Coro::nready |
507 | |
630 | |
508 | Returns the number of coroutines that are currently in the ready state, |
631 | Returns the number of coro that are currently in the ready state, |
509 | i.e. that can be switched to. The value C<0> means that the only runnable |
632 | i.e. that can be switched to by calling C<schedule> directory or |
|
|
633 | indirectly. The value C<0> means that the only runnable coro is the |
510 | coroutine is the currently running one, so C<cede> would have no effect, |
634 | currently running one, so C<cede> would have no effect, and C<schedule> |
511 | and C<schedule> would cause a deadlock unless there is an idle handler |
635 | would cause a deadlock unless there is an idle handler that wakes up some |
512 | that wakes up some coroutines. |
636 | coro. |
513 | |
637 | |
514 | =item my $guard = Coro::guard { ... } |
638 | =item my $guard = Coro::guard { ... } |
515 | |
639 | |
516 | This creates and returns a guard object. Nothing happens until the object |
640 | This function still exists, but is deprecated. Please use the |
517 | gets destroyed, in which case the codeblock given as argument will be |
641 | C<Guard::guard> function instead. |
518 | executed. This is useful to free locks or other resources in case of a |
|
|
519 | runtime error or when the coroutine gets canceled, as in both cases the |
|
|
520 | guard block will be executed. The guard object supports only one method, |
|
|
521 | C<< ->cancel >>, which will keep the codeblock from being executed. |
|
|
522 | |
642 | |
523 | Example: set some flag and clear it again when the coroutine gets canceled |
|
|
524 | or the function returns: |
|
|
525 | |
|
|
526 | sub do_something { |
|
|
527 | my $guard = Coro::guard { $busy = 0 }; |
|
|
528 | $busy = 1; |
|
|
529 | |
|
|
530 | # do something that requires $busy to be true |
|
|
531 | } |
|
|
532 | |
|
|
533 | =cut |
643 | =cut |
534 | |
644 | |
535 | sub guard(&) { |
645 | BEGIN { *guard = \&Guard::guard } |
536 | bless \(my $cb = $_[0]), "Coro::guard" |
|
|
537 | } |
|
|
538 | |
|
|
539 | sub Coro::guard::cancel { |
|
|
540 | ${$_[0]} = sub { }; |
|
|
541 | } |
|
|
542 | |
|
|
543 | sub Coro::guard::DESTROY { |
|
|
544 | ${$_[0]}->(); |
|
|
545 | } |
|
|
546 | |
|
|
547 | |
646 | |
548 | =item unblock_sub { ... } |
647 | =item unblock_sub { ... } |
549 | |
648 | |
550 | This utility function takes a BLOCK or code reference and "unblocks" it, |
649 | This utility function takes a BLOCK or code reference and "unblocks" it, |
551 | returning the new coderef. This means that the new coderef will return |
650 | returning a new coderef. Unblocking means that calling the new coderef |
552 | immediately without blocking, returning nothing, while the original code |
651 | will return immediately without blocking, returning nothing, while the |
553 | ref will be called (with parameters) from within its own coroutine. |
652 | original code ref will be called (with parameters) from within another |
|
|
653 | coro. |
554 | |
654 | |
555 | The reason this function exists is that many event libraries (such as the |
655 | The reason this function exists is that many event libraries (such as the |
556 | venerable L<Event|Event> module) are not coroutine-safe (a weaker form |
656 | venerable L<Event|Event> module) are not thread-safe (a weaker form |
557 | of thread-safety). This means you must not block within event callbacks, |
657 | of reentrancy). This means you must not block within event callbacks, |
558 | otherwise you might suffer from crashes or worse. |
658 | otherwise you might suffer from crashes or worse. The only event library |
|
|
659 | currently known that is safe to use without C<unblock_sub> is L<EV>. |
559 | |
660 | |
560 | This function allows your callbacks to block by executing them in another |
661 | This function allows your callbacks to block by executing them in another |
561 | coroutine where it is safe to block. One example where blocking is handy |
662 | coro where it is safe to block. One example where blocking is handy |
562 | is when you use the L<Coro::AIO|Coro::AIO> functions to save results to |
663 | is when you use the L<Coro::AIO|Coro::AIO> functions to save results to |
563 | disk. |
664 | disk, for example. |
564 | |
665 | |
565 | In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when |
666 | In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when |
566 | creating event callbacks that want to block. |
667 | creating event callbacks that want to block. |
|
|
668 | |
|
|
669 | If your handler does not plan to block (e.g. simply sends a message to |
|
|
670 | another coro, or puts some other coro into the ready queue), there is |
|
|
671 | no reason to use C<unblock_sub>. |
|
|
672 | |
|
|
673 | Note that you also need to use C<unblock_sub> for any other callbacks that |
|
|
674 | are indirectly executed by any C-based event loop. For example, when you |
|
|
675 | use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it |
|
|
676 | provides callbacks that are the result of some event callback, then you |
|
|
677 | must not block either, or use C<unblock_sub>. |
567 | |
678 | |
568 | =cut |
679 | =cut |
569 | |
680 | |
570 | our @unblock_queue; |
681 | our @unblock_queue; |
571 | |
682 | |
… | |
… | |
574 | # return immediately and can be reused) and because we cannot cede |
685 | # return immediately and can be reused) and because we cannot cede |
575 | # inside an event callback. |
686 | # inside an event callback. |
576 | our $unblock_scheduler = new Coro sub { |
687 | our $unblock_scheduler = new Coro sub { |
577 | while () { |
688 | while () { |
578 | while (my $cb = pop @unblock_queue) { |
689 | while (my $cb = pop @unblock_queue) { |
579 | # this is an inlined copy of async_pool |
690 | &async_pool (@$cb); |
580 | my $coro = (pop @async_pool) || new Coro \&pool_handler; |
|
|
581 | |
691 | |
582 | $coro->{_invoke} = $cb; |
|
|
583 | $coro->ready; |
|
|
584 | cede; # for short-lived callbacks, this reduces pressure on the coro pool |
692 | # for short-lived callbacks, this reduces pressure on the coro pool |
|
|
693 | # as the chance is very high that the async_poll coro will be back |
|
|
694 | # in the idle state when cede returns |
|
|
695 | cede; |
585 | } |
696 | } |
586 | schedule; # sleep well |
697 | schedule; # sleep well |
587 | } |
698 | } |
588 | }; |
699 | }; |
589 | $unblock_scheduler->desc ("[unblock_sub scheduler]"); |
700 | $unblock_scheduler->{desc} = "[unblock_sub scheduler]"; |
590 | |
701 | |
591 | sub unblock_sub(&) { |
702 | sub unblock_sub(&) { |
592 | my $cb = shift; |
703 | my $cb = shift; |
593 | |
704 | |
594 | sub { |
705 | sub { |
595 | unshift @unblock_queue, [$cb, @_]; |
706 | unshift @unblock_queue, [$cb, @_]; |
596 | $unblock_scheduler->ready; |
707 | $unblock_scheduler->ready; |
597 | } |
708 | } |
598 | } |
709 | } |
599 | |
710 | |
|
|
711 | =item $cb = Coro::rouse_cb |
|
|
712 | |
|
|
713 | Create and return a "rouse callback". That's a code reference that, |
|
|
714 | when called, will remember a copy of its arguments and notify the owner |
|
|
715 | coro of the callback. |
|
|
716 | |
|
|
717 | See the next function. |
|
|
718 | |
|
|
719 | =item @args = Coro::rouse_wait [$cb] |
|
|
720 | |
|
|
721 | Wait for the specified rouse callback (or the last one that was created in |
|
|
722 | this coro). |
|
|
723 | |
|
|
724 | As soon as the callback is invoked (or when the callback was invoked |
|
|
725 | before C<rouse_wait>), it will return the arguments originally passed to |
|
|
726 | the rouse callback. |
|
|
727 | |
|
|
728 | See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example. |
|
|
729 | |
600 | =back |
730 | =back |
601 | |
731 | |
602 | =cut |
732 | =cut |
603 | |
733 | |
604 | 1; |
734 | 1; |
605 | |
735 | |
|
|
736 | =head1 HOW TO WAIT FOR A CALLBACK |
|
|
737 | |
|
|
738 | It is very common for a coro to wait for some callback to be |
|
|
739 | called. This occurs naturally when you use coro in an otherwise |
|
|
740 | event-based program, or when you use event-based libraries. |
|
|
741 | |
|
|
742 | These typically register a callback for some event, and call that callback |
|
|
743 | when the event occured. In a coro, however, you typically want to |
|
|
744 | just wait for the event, simplyifying things. |
|
|
745 | |
|
|
746 | For example C<< AnyEvent->child >> registers a callback to be called when |
|
|
747 | a specific child has exited: |
|
|
748 | |
|
|
749 | my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... }); |
|
|
750 | |
|
|
751 | But from within a coro, you often just want to write this: |
|
|
752 | |
|
|
753 | my $status = wait_for_child $pid; |
|
|
754 | |
|
|
755 | Coro offers two functions specifically designed to make this easy, |
|
|
756 | C<Coro::rouse_cb> and C<Coro::rouse_wait>. |
|
|
757 | |
|
|
758 | The first function, C<rouse_cb>, generates and returns a callback that, |
|
|
759 | when invoked, will save its arguments and notify the coro that |
|
|
760 | created the callback. |
|
|
761 | |
|
|
762 | The second function, C<rouse_wait>, waits for the callback to be called |
|
|
763 | (by calling C<schedule> to go to sleep) and returns the arguments |
|
|
764 | originally passed to the callback. |
|
|
765 | |
|
|
766 | Using these functions, it becomes easy to write the C<wait_for_child> |
|
|
767 | function mentioned above: |
|
|
768 | |
|
|
769 | sub wait_for_child($) { |
|
|
770 | my ($pid) = @_; |
|
|
771 | |
|
|
772 | my $watcher = AnyEvent->child (pid => $pid, cb => Coro::rouse_cb); |
|
|
773 | |
|
|
774 | my ($rpid, $rstatus) = Coro::rouse_wait; |
|
|
775 | $rstatus |
|
|
776 | } |
|
|
777 | |
|
|
778 | In the case where C<rouse_cb> and C<rouse_wait> are not flexible enough, |
|
|
779 | you can roll your own, using C<schedule>: |
|
|
780 | |
|
|
781 | sub wait_for_child($) { |
|
|
782 | my ($pid) = @_; |
|
|
783 | |
|
|
784 | # store the current coro in $current, |
|
|
785 | # and provide result variables for the closure passed to ->child |
|
|
786 | my $current = $Coro::current; |
|
|
787 | my ($done, $rstatus); |
|
|
788 | |
|
|
789 | # pass a closure to ->child |
|
|
790 | my $watcher = AnyEvent->child (pid => $pid, cb => sub { |
|
|
791 | $rstatus = $_[1]; # remember rstatus |
|
|
792 | $done = 1; # mark $rstatus as valud |
|
|
793 | }); |
|
|
794 | |
|
|
795 | # wait until the closure has been called |
|
|
796 | schedule while !$done; |
|
|
797 | |
|
|
798 | $rstatus |
|
|
799 | } |
|
|
800 | |
|
|
801 | |
606 | =head1 BUGS/LIMITATIONS |
802 | =head1 BUGS/LIMITATIONS |
607 | |
803 | |
608 | - you must make very sure that no coro is still active on global |
804 | =over 4 |
609 | destruction. very bad things might happen otherwise (usually segfaults). |
|
|
610 | |
805 | |
|
|
806 | =item fork with pthread backend |
|
|
807 | |
|
|
808 | When Coro is compiled using the pthread backend (which isn't recommended |
|
|
809 | but required on many BSDs as their libcs are completely broken), then |
|
|
810 | coro will not survive a fork. There is no known workaround except to |
|
|
811 | fix your libc and use a saner backend. |
|
|
812 | |
|
|
813 | =item perl process emulation ("threads") |
|
|
814 | |
611 | - this module is not thread-safe. You should only ever use this module |
815 | This module is not perl-pseudo-thread-safe. You should only ever use this |
612 | from the same thread (this requirement might be loosened in the future |
816 | module from the first thread (this requirement might be removed in the |
613 | to allow per-thread schedulers, but Coro::State does not yet allow |
817 | future to allow per-thread schedulers, but Coro::State does not yet allow |
614 | this). |
818 | this). I recommend disabling thread support and using processes, as having |
|
|
819 | the windows process emulation enabled under unix roughly halves perl |
|
|
820 | performance, even when not used. |
|
|
821 | |
|
|
822 | =item coro switching is not signal safe |
|
|
823 | |
|
|
824 | You must not switch to another coro from within a signal handler |
|
|
825 | (only relevant with %SIG - most event libraries provide safe signals). |
|
|
826 | |
|
|
827 | That means you I<MUST NOT> call any function that might "block" the |
|
|
828 | current coro - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or |
|
|
829 | anything that calls those. Everything else, including calling C<ready>, |
|
|
830 | works. |
|
|
831 | |
|
|
832 | =back |
|
|
833 | |
615 | |
834 | |
616 | =head1 SEE ALSO |
835 | =head1 SEE ALSO |
617 | |
836 | |
|
|
837 | Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>. |
|
|
838 | |
|
|
839 | Debugging: L<Coro::Debug>. |
|
|
840 | |
618 | Support/Utility: L<Coro::Specific>, L<Coro::State>, L<Coro::Util>. |
841 | Support/Utility: L<Coro::Specific>, L<Coro::Util>. |
619 | |
842 | |
620 | Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>. |
843 | Locking and IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, |
|
|
844 | L<Coro::SemaphoreSet>, L<Coro::RWLock>. |
621 | |
845 | |
622 | Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>. |
846 | I/O and Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>. |
623 | |
847 | |
624 | Embedding: L<Coro:MakeMaker> |
848 | Compatibility with other modules: L<Coro::LWP> (but see also L<AnyEvent::HTTP> for |
|
|
849 | a better-working alternative), L<Coro::BDB>, L<Coro::Storable>, |
|
|
850 | L<Coro::Select>. |
|
|
851 | |
|
|
852 | XS API: L<Coro::MakeMaker>. |
|
|
853 | |
|
|
854 | Low level Configuration, Thread Environment, Continuations: L<Coro::State>. |
625 | |
855 | |
626 | =head1 AUTHOR |
856 | =head1 AUTHOR |
627 | |
857 | |
628 | Marc Lehmann <schmorp@schmorp.de> |
858 | Marc Lehmann <schmorp@schmorp.de> |
629 | http://home.schmorp.de/ |
859 | http://home.schmorp.de/ |