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 use din this module also |
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26 | guarentees 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 (see section of same name for more |
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46 | details) ported to unix, and as such act as processes), Coro provides |
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47 | a full shared address space, which makes communication between threads |
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48 | very easy. And Coro's threads are fast, too: disabling the Windows |
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49 | process emulation code in your perl and using Coro can easily result in |
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50 | a two to four times speed increase for your programs. A parallel matrix |
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51 | multiplication benchmark runs over 300 times faster on a single core than |
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52 | perl's pseudo-threads on a quad core using 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 common::sense; |
45 | no warnings "uninitialized"; |
73 | |
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74 | use Carp (); |
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75 | |
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76 | use Guard (); |
46 | |
77 | |
47 | use Coro::State; |
78 | use Coro::State; |
48 | |
79 | |
49 | use base qw(Coro::State Exporter); |
80 | use base qw(Coro::State Exporter); |
50 | |
81 | |
51 | our $idle; # idle handler |
82 | our $idle; # idle handler |
52 | our $main; # main coroutine |
83 | our $main; # main coro |
53 | our $current; # current coroutine |
84 | our $current; # current coro |
54 | |
85 | |
55 | our $VERSION = '3.56'; |
86 | our $VERSION = 5.2; |
56 | |
87 | |
57 | our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub); |
88 | our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub rouse_cb rouse_wait); |
58 | our %EXPORT_TAGS = ( |
89 | our %EXPORT_TAGS = ( |
59 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
90 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
60 | ); |
91 | ); |
61 | our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready)); |
92 | our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready)); |
62 | |
93 | |
63 | { |
94 | =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 | |
95 | |
97 | =over 4 |
96 | =over 4 |
98 | |
97 | |
99 | =item $main |
98 | =item $Coro::main |
100 | |
99 | |
101 | This coroutine represents the main program. |
100 | This variable stores the Coro object that represents the main |
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101 | program. While you cna C<ready> it and do most other things you can do to |
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102 | coro, it is mainly useful to compare again C<$Coro::current>, to see |
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103 | whether you are running in the main program or not. |
102 | |
104 | |
103 | =cut |
105 | =cut |
104 | |
106 | |
105 | $main = new Coro; |
107 | # $main is now being initialised by Coro::State |
106 | |
108 | |
107 | =item $current (or as function: current) |
109 | =item $Coro::current |
108 | |
110 | |
109 | The current coroutine (the last coroutine switched to). The initial value |
111 | The Coro object representing the current coro (the last |
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112 | coro that the Coro scheduler switched to). The initial value is |
110 | is C<$main> (of course). |
113 | C<$Coro::main> (of course). |
111 | |
114 | |
112 | This variable is B<strictly> I<read-only>. It is provided for performance |
115 | This variable is B<strictly> I<read-only>. You can take copies of the |
113 | reasons. If performance is not essentiel you are encouraged to use the |
116 | value stored in it and use it as any other Coro object, but you must |
114 | C<Coro::current> function instead. |
117 | not otherwise modify the variable itself. |
115 | |
118 | |
116 | =cut |
119 | =cut |
117 | |
120 | |
118 | # maybe some other module used Coro::Specific before... |
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119 | $main->{specific} = $current->{specific} |
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120 | if $current; |
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121 | |
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122 | _set_current $main; |
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123 | |
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124 | sub current() { $current } |
121 | sub current() { $current } # [DEPRECATED] |
125 | |
122 | |
126 | =item $idle |
123 | =item $Coro::idle |
127 | |
124 | |
128 | A callback that is called whenever the scheduler finds no ready coroutines |
125 | This variable is mainly useful to integrate Coro into event loops. It is |
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126 | usually better to rely on L<Coro::AnyEvent> or L<Coro::EV>, as this is |
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127 | pretty low-level functionality. |
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128 | |
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129 | This variable stores a Coro object that is put into the ready queue when |
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130 | there are no other ready threads (without invoking any ready hooks). |
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131 | |
129 | to run. The default implementation prints "FATAL: deadlock detected" and |
132 | The default implementation dies with "FATAL: deadlock detected.", followed |
130 | exits, because the program has no other way to continue. |
133 | by a thread listing, because the program has no other way to continue. |
131 | |
134 | |
132 | This hook is overwritten by modules such as C<Coro::Timer> and |
135 | This hook is overwritten by modules such as C<Coro::EV> and |
133 | C<Coro::Event> to wait on an external event that hopefully wake up a |
136 | C<Coro::AnyEvent> to wait on an external event that hopefully wake up a |
134 | coroutine so the scheduler can run it. |
137 | coro so the scheduler can run it. |
135 | |
138 | |
136 | Please note that if your callback recursively invokes perl (e.g. for event |
139 | See L<Coro::EV> or L<Coro::AnyEvent> for examples of using this technique. |
137 | handlers), then it must be prepared to be called recursively. |
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138 | |
140 | |
139 | =cut |
141 | =cut |
140 | |
142 | |
141 | $idle = sub { |
143 | $idle = new Coro sub { |
142 | require Carp; |
144 | require Coro::Debug; |
143 | Carp::croak ("FATAL: deadlock detected"); |
145 | die "FATAL: deadlock detected.\n" |
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146 | . Coro::Debug::ps_listing (); |
144 | }; |
147 | }; |
145 | |
148 | |
146 | sub _cancel { |
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147 | my ($self) = @_; |
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148 | |
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149 | # free coroutine data and mark as destructed |
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150 | $self->_destroy |
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151 | or return; |
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152 | |
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153 | # call all destruction callbacks |
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154 | $_->(@{$self->{status}}) |
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155 | for @{(delete $self->{destroy_cb}) || []}; |
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156 | } |
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157 | |
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158 | # this coroutine is necessary because a coroutine |
149 | # this coro is necessary because a coro |
159 | # cannot destroy itself. |
150 | # cannot destroy itself. |
160 | my @destroy; |
151 | our @destroy; |
161 | my $manager; |
152 | our $manager; |
162 | |
153 | |
163 | $manager = new Coro sub { |
154 | $manager = new Coro sub { |
164 | while () { |
155 | while () { |
165 | (shift @destroy)->_cancel |
156 | Coro::State::cancel shift @destroy |
166 | while @destroy; |
157 | while @destroy; |
167 | |
158 | |
168 | &schedule; |
159 | &schedule; |
169 | } |
160 | } |
170 | }; |
161 | }; |
171 | |
162 | $manager->{desc} = "[coro manager]"; |
172 | $manager->prio (PRIO_MAX); |
163 | $manager->prio (PRIO_MAX); |
173 | |
164 | |
174 | # static methods. not really. |
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175 | |
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176 | =back |
165 | =back |
177 | |
166 | |
178 | =head2 STATIC METHODS |
167 | =head1 SIMPLE CORO CREATION |
179 | |
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180 | Static methods are actually functions that operate on the current coroutine only. |
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181 | |
168 | |
182 | =over 4 |
169 | =over 4 |
183 | |
170 | |
184 | =item async { ... } [@args...] |
171 | =item async { ... } [@args...] |
185 | |
172 | |
186 | Create a new asynchronous coroutine and return it's coroutine object |
173 | Create a new coro and return its Coro object (usually |
187 | (usually unused). When the sub returns the new coroutine is automatically |
174 | unused). The coro will be put into the ready queue, so |
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175 | it will start running automatically on the next scheduler run. |
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176 | |
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177 | The first argument is a codeblock/closure that should be executed in the |
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178 | coro. When it returns argument returns the coro is automatically |
188 | terminated. |
179 | terminated. |
189 | |
180 | |
190 | Calling C<exit> in a coroutine will not work correctly, so do not do that. |
181 | The remaining arguments are passed as arguments to the closure. |
191 | |
182 | |
192 | When the coroutine dies, the program will exit, just as in the main |
183 | See the C<Coro::State::new> constructor for info about the coro |
193 | program. |
184 | environment in which coro are executed. |
194 | |
185 | |
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186 | Calling C<exit> in a coro will do the same as calling exit outside |
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187 | the coro. Likewise, when the coro dies, the program will exit, |
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188 | just as it would in the main program. |
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189 | |
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190 | If you do not want that, you can provide a default C<die> handler, or |
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191 | simply avoid dieing (by use of C<eval>). |
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192 | |
195 | # create a new coroutine that just prints its arguments |
193 | Example: Create a new coro that just prints its arguments. |
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194 | |
196 | async { |
195 | async { |
197 | print "@_\n"; |
196 | print "@_\n"; |
198 | } 1,2,3,4; |
197 | } 1,2,3,4; |
199 | |
198 | |
200 | =cut |
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201 | |
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202 | sub async(&@) { |
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203 | my $coro = new Coro @_; |
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204 | $coro->ready; |
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205 | $coro |
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206 | } |
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207 | |
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208 | =item async_pool { ... } [@args...] |
199 | =item async_pool { ... } [@args...] |
209 | |
200 | |
210 | Similar to C<async>, but uses a coroutine pool, so you should not call |
201 | Similar to C<async>, but uses a coro pool, so you should not call |
211 | terminate or join (although you are allowed to), and you get a coroutine |
202 | terminate or join on it (although you are allowed to), and you get a |
212 | that might have executed other code already (which can be good or bad :). |
203 | coro that might have executed other code already (which can be good |
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204 | or bad :). |
213 | |
205 | |
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206 | On the plus side, this function is about twice as fast as creating (and |
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207 | destroying) a completely new coro, so if you need a lot of generic |
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208 | coros in quick successsion, use C<async_pool>, not C<async>. |
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209 | |
214 | Also, the block is executed in an C<eval> context and a warning will be |
210 | The code block is executed in an C<eval> context and a warning will be |
215 | issued in case of an exception instead of terminating the program, as |
211 | issued in case of an exception instead of terminating the program, as |
216 | C<async> does. As the coroutine is being reused, stuff like C<on_destroy> |
212 | C<async> does. As the coro is being reused, stuff like C<on_destroy> |
217 | will not work in the expected way, unless you call terminate or cancel, |
213 | will not work in the expected way, unless you call terminate or cancel, |
218 | which somehow defeats the purpose of pooling. |
214 | which somehow defeats the purpose of pooling (but is fine in the |
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215 | exceptional case). |
219 | |
216 | |
220 | The priority will be reset to C<0> after each job, otherwise the coroutine |
217 | The priority will be reset to C<0> after each run, tracing will be |
221 | will be re-used "as-is". |
218 | disabled, the description will be reset and the default output filehandle |
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219 | gets restored, so you can change all these. Otherwise the coro will |
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220 | be re-used "as-is": most notably if you change other per-coro global |
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221 | stuff such as C<$/> you I<must needs> revert that change, which is most |
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222 | simply done by using local as in: C<< local $/ >>. |
222 | |
223 | |
223 | The pool size is limited to 8 idle coroutines (this can be adjusted by |
224 | The idle pool size is limited to C<8> idle coros (this can be |
224 | changing $Coro::POOL_SIZE), and there can be as many non-idle coros as |
225 | adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle |
225 | required. |
226 | coros as required. |
226 | |
227 | |
227 | If you are concerned about pooled coroutines growing a lot because a |
228 | If you are concerned about pooled coros growing a lot because a |
228 | single C<async_pool> used a lot of stackspace you can e.g. C<async_pool { |
229 | single C<async_pool> used a lot of stackspace you can e.g. C<async_pool |
229 | terminate }> once per second or so to slowly replenish the pool. |
230 | { terminate }> once per second or so to slowly replenish the pool. In |
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231 | addition to that, when the stacks used by a handler grows larger than 32kb |
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232 | (adjustable via $Coro::POOL_RSS) it will also be destroyed. |
230 | |
233 | |
231 | =cut |
234 | =cut |
232 | |
235 | |
233 | our $POOL_SIZE = 8; |
236 | our $POOL_SIZE = 8; |
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237 | our $POOL_RSS = 32 * 1024; |
234 | our @pool; |
238 | our @async_pool; |
235 | |
239 | |
236 | sub pool_handler { |
240 | sub pool_handler { |
237 | while () { |
241 | while () { |
238 | eval { |
242 | eval { |
239 | my ($cb, @arg) = @{ delete $current->{_invoke} or return }; |
243 | &{&_pool_handler} while 1; |
240 | $cb->(@arg); |
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241 | }; |
244 | }; |
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245 | |
242 | warn $@ if $@; |
246 | warn $@ if $@; |
243 | |
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244 | last if @pool >= $POOL_SIZE; |
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245 | push @pool, $current; |
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246 | |
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247 | $current->save (Coro::State::SAVE_DEF); |
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248 | $current->prio (0); |
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249 | schedule; |
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250 | } |
247 | } |
251 | } |
248 | } |
252 | |
249 | |
253 | sub async_pool(&@) { |
250 | =back |
254 | # this is also inlined into the unlock_scheduler |
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255 | my $coro = (pop @pool or new Coro \&pool_handler); |
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256 | |
251 | |
257 | $coro->{_invoke} = [@_]; |
252 | =head1 STATIC METHODS |
258 | $coro->ready; |
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259 | |
253 | |
260 | $coro |
254 | Static methods are actually functions that implicitly operate on the |
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255 | current coro. |
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256 | |
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257 | =over 4 |
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258 | |
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259 | =item schedule |
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260 | |
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261 | Calls the scheduler. The scheduler will find the next coro that is |
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262 | to be run from the ready queue and switches to it. The next coro |
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263 | to be run is simply the one with the highest priority that is longest |
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264 | in its ready queue. If there is no coro ready, it will call the |
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265 | C<$Coro::idle> hook. |
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266 | |
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267 | Please note that the current coro will I<not> be put into the ready |
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268 | queue, so calling this function usually means you will never be called |
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269 | again unless something else (e.g. an event handler) calls C<< ->ready >>, |
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270 | thus waking you up. |
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271 | |
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272 | This makes C<schedule> I<the> generic method to use to block the current |
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273 | coro and wait for events: first you remember the current coro in |
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274 | a variable, then arrange for some callback of yours to call C<< ->ready |
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275 | >> on that once some event happens, and last you call C<schedule> to put |
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276 | yourself to sleep. Note that a lot of things can wake your coro up, |
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277 | so you need to check whether the event indeed happened, e.g. by storing the |
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278 | status in a variable. |
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279 | |
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280 | See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks. |
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281 | |
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282 | =item cede |
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283 | |
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284 | "Cede" to other coros. This function puts the current coro into |
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285 | the ready queue and calls C<schedule>, which has the effect of giving |
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286 | up the current "timeslice" to other coros of the same or higher |
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287 | priority. Once your coro gets its turn again it will automatically be |
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288 | resumed. |
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289 | |
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290 | This function is often called C<yield> in other languages. |
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291 | |
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292 | =item Coro::cede_notself |
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293 | |
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294 | Works like cede, but is not exported by default and will cede to I<any> |
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295 | coro, regardless of priority. This is useful sometimes to ensure |
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296 | progress is made. |
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297 | |
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298 | =item terminate [arg...] |
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299 | |
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300 | Terminates the current coro with the given status values (see L<cancel>). |
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301 | |
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302 | =item Coro::on_enter BLOCK, Coro::on_leave BLOCK |
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303 | |
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304 | These function install enter and leave winders in the current scope. The |
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305 | enter block will be executed when on_enter is called and whenever the |
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306 | current coro is re-entered by the scheduler, while the leave block is |
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307 | executed whenever the current coro is blocked by the scheduler, and |
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308 | also when the containing scope is exited (by whatever means, be it exit, |
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|
309 | die, last etc.). |
|
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310 | |
|
|
311 | I<Neither invoking the scheduler, nor exceptions, are allowed within those |
|
|
312 | BLOCKs>. That means: do not even think about calling C<die> without an |
|
|
313 | eval, and do not even think of entering the scheduler in any way. |
|
|
314 | |
|
|
315 | Since both BLOCKs are tied to the current scope, they will automatically |
|
|
316 | be removed when the current scope exits. |
|
|
317 | |
|
|
318 | These functions implement the same concept as C<dynamic-wind> in scheme |
|
|
319 | does, and are useful when you want to localise some resource to a specific |
|
|
320 | coro. |
|
|
321 | |
|
|
322 | They slow down thread switching considerably for coros that use them |
|
|
323 | (about 40% for a BLOCK with a single assignment, so thread switching is |
|
|
324 | still reasonably fast if the handlers are fast). |
|
|
325 | |
|
|
326 | These functions are best understood by an example: The following function |
|
|
327 | will change the current timezone to "Antarctica/South_Pole", which |
|
|
328 | requires a call to C<tzset>, but by using C<on_enter> and C<on_leave>, |
|
|
329 | which remember/change the current timezone and restore the previous |
|
|
330 | value, respectively, the timezone is only changed for the coro that |
|
|
331 | installed those handlers. |
|
|
332 | |
|
|
333 | use POSIX qw(tzset); |
|
|
334 | |
|
|
335 | async { |
|
|
336 | my $old_tz; # store outside TZ value here |
|
|
337 | |
|
|
338 | Coro::on_enter { |
|
|
339 | $old_tz = $ENV{TZ}; # remember the old value |
|
|
340 | |
|
|
341 | $ENV{TZ} = "Antarctica/South_Pole"; |
|
|
342 | tzset; # enable new value |
|
|
343 | }; |
|
|
344 | |
|
|
345 | Coro::on_leave { |
|
|
346 | $ENV{TZ} = $old_tz; |
|
|
347 | tzset; # restore old value |
|
|
348 | }; |
|
|
349 | |
|
|
350 | # at this place, the timezone is Antarctica/South_Pole, |
|
|
351 | # without disturbing the TZ of any other coro. |
|
|
352 | }; |
|
|
353 | |
|
|
354 | This can be used to localise about any resource (locale, uid, current |
|
|
355 | working directory etc.) to a block, despite the existance of other |
|
|
356 | coros. |
|
|
357 | |
|
|
358 | Another interesting example implements time-sliced multitasking using |
|
|
359 | interval timers (this could obviously be optimised, but does the job): |
|
|
360 | |
|
|
361 | # "timeslice" the given block |
|
|
362 | sub timeslice(&) { |
|
|
363 | use Time::HiRes (); |
|
|
364 | |
|
|
365 | Coro::on_enter { |
|
|
366 | # on entering the thread, we set an VTALRM handler to cede |
|
|
367 | $SIG{VTALRM} = sub { cede }; |
|
|
368 | # and then start the interval timer |
|
|
369 | Time::HiRes::setitimer &Time::HiRes::ITIMER_VIRTUAL, 0.01, 0.01; |
|
|
370 | }; |
|
|
371 | Coro::on_leave { |
|
|
372 | # on leaving the thread, we stop the interval timer again |
|
|
373 | Time::HiRes::setitimer &Time::HiRes::ITIMER_VIRTUAL, 0, 0; |
|
|
374 | }; |
|
|
375 | |
|
|
376 | &{+shift}; |
|
|
377 | } |
|
|
378 | |
|
|
379 | # use like this: |
|
|
380 | timeslice { |
|
|
381 | # The following is an endless loop that would normally |
|
|
382 | # monopolise the process. Since it runs in a timesliced |
|
|
383 | # environment, it will regularly cede to other threads. |
|
|
384 | while () { } |
|
|
385 | }; |
|
|
386 | |
|
|
387 | |
|
|
388 | =item killall |
|
|
389 | |
|
|
390 | Kills/terminates/cancels all coros except the currently running one. |
|
|
391 | |
|
|
392 | Note that while this will try to free some of the main interpreter |
|
|
393 | resources if the calling coro isn't the main coro, but one |
|
|
394 | cannot free all of them, so if a coro that is not the main coro |
|
|
395 | calls this function, there will be some one-time resource leak. |
|
|
396 | |
|
|
397 | =cut |
|
|
398 | |
|
|
399 | sub killall { |
|
|
400 | for (Coro::State::list) { |
|
|
401 | $_->cancel |
|
|
402 | if $_ != $current && UNIVERSAL::isa $_, "Coro"; |
|
|
403 | } |
261 | } |
404 | } |
262 | |
405 | |
263 | =item schedule |
406 | =back |
264 | |
407 | |
265 | Calls the scheduler. Please note that the current coroutine will not be put |
408 | =head1 CORO OBJECT METHODS |
266 | into the ready queue, so calling this function usually means you will |
|
|
267 | never be called again unless something else (e.g. an event handler) calls |
|
|
268 | ready. |
|
|
269 | |
409 | |
270 | The canonical way to wait on external events is this: |
410 | These are the methods you can call on coro objects (or to create |
|
|
411 | them). |
271 | |
412 | |
|
|
413 | =over 4 |
|
|
414 | |
|
|
415 | =item new Coro \&sub [, @args...] |
|
|
416 | |
|
|
417 | Create a new coro and return it. When the sub returns, the coro |
|
|
418 | automatically terminates as if C<terminate> with the returned values were |
|
|
419 | called. To make the coro run you must first put it into the ready |
|
|
420 | queue by calling the ready method. |
|
|
421 | |
|
|
422 | See C<async> and C<Coro::State::new> for additional info about the |
|
|
423 | coro environment. |
|
|
424 | |
|
|
425 | =cut |
|
|
426 | |
|
|
427 | sub _coro_run { |
|
|
428 | terminate &{+shift}; |
|
|
429 | } |
|
|
430 | |
|
|
431 | =item $success = $coro->ready |
|
|
432 | |
|
|
433 | Put the given coro into the end of its ready queue (there is one |
|
|
434 | queue for each priority) and return true. If the coro is already in |
|
|
435 | the ready queue, do nothing and return false. |
|
|
436 | |
|
|
437 | This ensures that the scheduler will resume this coro automatically |
|
|
438 | once all the coro of higher priority and all coro of the same |
|
|
439 | priority that were put into the ready queue earlier have been resumed. |
|
|
440 | |
|
|
441 | =item $coro->suspend |
|
|
442 | |
|
|
443 | Suspends the specified coro. A suspended coro works just like any other |
|
|
444 | coro, except that the scheduler will not select a suspended coro for |
|
|
445 | execution. |
|
|
446 | |
|
|
447 | Suspending a coro can be useful when you want to keep the coro from |
|
|
448 | running, but you don't want to destroy it, or when you want to temporarily |
|
|
449 | freeze a coro (e.g. for debugging) to resume it later. |
|
|
450 | |
|
|
451 | A scenario for the former would be to suspend all (other) coros after a |
|
|
452 | fork and keep them alive, so their destructors aren't called, but new |
|
|
453 | coros can be created. |
|
|
454 | |
|
|
455 | =item $coro->resume |
|
|
456 | |
|
|
457 | If the specified coro was suspended, it will be resumed. Note that when |
|
|
458 | the coro was in the ready queue when it was suspended, it might have been |
|
|
459 | unreadied by the scheduler, so an activation might have been lost. |
|
|
460 | |
|
|
461 | To avoid this, it is best to put a suspended coro into the ready queue |
|
|
462 | unconditionally, as every synchronisation mechanism must protect itself |
|
|
463 | against spurious wakeups, and the one in the Coro family certainly do |
|
|
464 | that. |
|
|
465 | |
|
|
466 | =item $is_ready = $coro->is_ready |
|
|
467 | |
|
|
468 | Returns true iff the Coro object is in the ready queue. Unless the Coro |
|
|
469 | object gets destroyed, it will eventually be scheduled by the scheduler. |
|
|
470 | |
|
|
471 | =item $is_running = $coro->is_running |
|
|
472 | |
|
|
473 | Returns true iff the Coro object is currently running. Only one Coro object |
|
|
474 | can ever be in the running state (but it currently is possible to have |
|
|
475 | multiple running Coro::States). |
|
|
476 | |
|
|
477 | =item $is_suspended = $coro->is_suspended |
|
|
478 | |
|
|
479 | Returns true iff this Coro object has been suspended. Suspended Coros will |
|
|
480 | not ever be scheduled. |
|
|
481 | |
|
|
482 | =item $coro->cancel (arg...) |
|
|
483 | |
|
|
484 | Terminates the given Coro and makes it return the given arguments as |
|
|
485 | status (default: the empty list). Never returns if the Coro is the |
|
|
486 | current Coro. |
|
|
487 | |
|
|
488 | =cut |
|
|
489 | |
|
|
490 | sub cancel { |
|
|
491 | my $self = shift; |
|
|
492 | |
|
|
493 | if ($current == $self) { |
|
|
494 | terminate @_; |
|
|
495 | } else { |
|
|
496 | $self->{_status} = [@_]; |
|
|
497 | Coro::State::cancel $self; |
272 | { |
498 | } |
273 | # remember current coroutine |
499 | } |
|
|
500 | |
|
|
501 | =item $coro->schedule_to |
|
|
502 | |
|
|
503 | Puts the current coro to sleep (like C<Coro::schedule>), but instead |
|
|
504 | of continuing with the next coro from the ready queue, always switch to |
|
|
505 | the given coro object (regardless of priority etc.). The readyness |
|
|
506 | state of that coro isn't changed. |
|
|
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->cede_to |
|
|
512 | |
|
|
513 | Like C<schedule_to>, but puts the current coro into the ready |
|
|
514 | queue. This has the effect of temporarily switching to the given |
|
|
515 | coro, and continuing some time later. |
|
|
516 | |
|
|
517 | This is an advanced method for special cases - I'd love to hear about any |
|
|
518 | uses for this one. |
|
|
519 | |
|
|
520 | =item $coro->throw ([$scalar]) |
|
|
521 | |
|
|
522 | If C<$throw> is specified and defined, it will be thrown as an exception |
|
|
523 | inside the coro at the next convenient point in time. Otherwise |
|
|
524 | clears the exception object. |
|
|
525 | |
|
|
526 | Coro will check for the exception each time a schedule-like-function |
|
|
527 | returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down |
|
|
528 | >>, C<< Coro::Handle->readable >> and so on. Most of these functions |
|
|
529 | detect this case and return early in case an exception is pending. |
|
|
530 | |
|
|
531 | The exception object will be thrown "as is" with the specified scalar in |
|
|
532 | C<$@>, i.e. if it is a string, no line number or newline will be appended |
|
|
533 | (unlike with C<die>). |
|
|
534 | |
|
|
535 | This can be used as a softer means than C<cancel> to ask a coro to |
|
|
536 | end itself, although there is no guarantee that the exception will lead to |
|
|
537 | termination, and if the exception isn't caught it might well end the whole |
|
|
538 | program. |
|
|
539 | |
|
|
540 | You might also think of C<throw> as being the moral equivalent of |
|
|
541 | C<kill>ing a coro with a signal (in this case, a scalar). |
|
|
542 | |
|
|
543 | =item $coro->join |
|
|
544 | |
|
|
545 | Wait until the coro terminates and return any values given to the |
|
|
546 | C<terminate> or C<cancel> functions. C<join> can be called concurrently |
|
|
547 | from multiple coro, and all will be resumed and given the status |
|
|
548 | return once the C<$coro> terminates. |
|
|
549 | |
|
|
550 | =cut |
|
|
551 | |
|
|
552 | sub join { |
|
|
553 | my $self = shift; |
|
|
554 | |
|
|
555 | unless ($self->{_status}) { |
274 | my $current = $Coro::current; |
556 | my $current = $current; |
275 | |
557 | |
276 | # register a hypothetical event handler |
558 | push @{$self->{_on_destroy}}, sub { |
277 | on_event_invoke sub { |
|
|
278 | # wake up sleeping coroutine |
|
|
279 | $current->ready; |
559 | $current->ready; |
280 | undef $current; |
560 | undef $current; |
281 | }; |
561 | }; |
282 | |
562 | |
283 | # call schedule until event occured. |
|
|
284 | # in case we are woken up for other reasons |
|
|
285 | # (current still defined), loop. |
|
|
286 | Coro::schedule while $current; |
|
|
287 | } |
|
|
288 | |
|
|
289 | =item cede |
|
|
290 | |
|
|
291 | "Cede" to other coroutines. This function puts the current coroutine into the |
|
|
292 | ready queue and calls C<schedule>, which has the effect of giving up the |
|
|
293 | current "timeslice" to other coroutines of the same or higher priority. |
|
|
294 | |
|
|
295 | Returns true if at least one coroutine switch has happened. |
|
|
296 | |
|
|
297 | =item Coro::cede_notself |
|
|
298 | |
|
|
299 | Works like cede, but is not exported by default and will cede to any |
|
|
300 | coroutine, regardless of priority, once. |
|
|
301 | |
|
|
302 | Returns true if at least one coroutine switch has happened. |
|
|
303 | |
|
|
304 | =item terminate [arg...] |
|
|
305 | |
|
|
306 | Terminates the current coroutine with the given status values (see L<cancel>). |
|
|
307 | |
|
|
308 | =cut |
|
|
309 | |
|
|
310 | sub terminate { |
|
|
311 | $current->cancel (@_); |
|
|
312 | } |
|
|
313 | |
|
|
314 | =back |
|
|
315 | |
|
|
316 | # dynamic methods |
|
|
317 | |
|
|
318 | =head2 COROUTINE METHODS |
|
|
319 | |
|
|
320 | These are the methods you can call on coroutine objects. |
|
|
321 | |
|
|
322 | =over 4 |
|
|
323 | |
|
|
324 | =item new Coro \&sub [, @args...] |
|
|
325 | |
|
|
326 | Create a new coroutine and return it. When the sub returns the coroutine |
|
|
327 | automatically terminates as if C<terminate> with the returned values were |
|
|
328 | called. To make the coroutine run you must first put it into the ready queue |
|
|
329 | by calling the ready method. |
|
|
330 | |
|
|
331 | Calling C<exit> in a coroutine will not work correctly, so do not do that. |
|
|
332 | |
|
|
333 | =cut |
|
|
334 | |
|
|
335 | sub _run_coro { |
|
|
336 | terminate &{+shift}; |
|
|
337 | } |
|
|
338 | |
|
|
339 | sub new { |
|
|
340 | my $class = shift; |
|
|
341 | |
|
|
342 | $class->SUPER::new (\&_run_coro, @_) |
|
|
343 | } |
|
|
344 | |
|
|
345 | =item $success = $coroutine->ready |
|
|
346 | |
|
|
347 | Put the given coroutine into the ready queue (according to it's priority) |
|
|
348 | and return true. If the coroutine is already in the ready queue, do nothing |
|
|
349 | and return false. |
|
|
350 | |
|
|
351 | =item $is_ready = $coroutine->is_ready |
|
|
352 | |
|
|
353 | Return wether the coroutine is currently the ready queue or not, |
|
|
354 | |
|
|
355 | =item $coroutine->cancel (arg...) |
|
|
356 | |
|
|
357 | Terminates the given coroutine and makes it return the given arguments as |
|
|
358 | status (default: the empty list). Never returns if the coroutine is the |
|
|
359 | current coroutine. |
|
|
360 | |
|
|
361 | =cut |
|
|
362 | |
|
|
363 | sub cancel { |
|
|
364 | my $self = shift; |
|
|
365 | $self->{status} = [@_]; |
|
|
366 | |
|
|
367 | if ($current == $self) { |
|
|
368 | push @destroy, $self; |
|
|
369 | $manager->ready; |
|
|
370 | &schedule while 1; |
|
|
371 | } else { |
|
|
372 | $self->_cancel; |
|
|
373 | } |
|
|
374 | } |
|
|
375 | |
|
|
376 | =item $coroutine->join |
|
|
377 | |
|
|
378 | Wait until the coroutine terminates and return any values given to the |
|
|
379 | C<terminate> or C<cancel> functions. C<join> can be called multiple times |
|
|
380 | from multiple coroutine. |
|
|
381 | |
|
|
382 | =cut |
|
|
383 | |
|
|
384 | sub join { |
|
|
385 | my $self = shift; |
|
|
386 | |
|
|
387 | unless ($self->{status}) { |
|
|
388 | my $current = $current; |
|
|
389 | |
|
|
390 | push @{$self->{destroy_cb}}, sub { |
|
|
391 | $current->ready; |
|
|
392 | undef $current; |
|
|
393 | }; |
|
|
394 | |
|
|
395 | &schedule while $current; |
563 | &schedule while $current; |
396 | } |
564 | } |
397 | |
565 | |
398 | wantarray ? @{$self->{status}} : $self->{status}[0]; |
566 | wantarray ? @{$self->{_status}} : $self->{_status}[0]; |
399 | } |
567 | } |
400 | |
568 | |
401 | =item $coroutine->on_destroy (\&cb) |
569 | =item $coro->on_destroy (\&cb) |
402 | |
570 | |
403 | Registers a callback that is called when this coroutine gets destroyed, |
571 | Registers a callback that is called when this coro gets destroyed, |
404 | but before it is joined. The callback gets passed the terminate arguments, |
572 | but before it is joined. The callback gets passed the terminate arguments, |
405 | if any. |
573 | if any, and I<must not> die, under any circumstances. |
406 | |
574 | |
407 | =cut |
575 | =cut |
408 | |
576 | |
409 | sub on_destroy { |
577 | sub on_destroy { |
410 | my ($self, $cb) = @_; |
578 | my ($self, $cb) = @_; |
411 | |
579 | |
412 | push @{ $self->{destroy_cb} }, $cb; |
580 | push @{ $self->{_on_destroy} }, $cb; |
413 | } |
581 | } |
414 | |
582 | |
415 | =item $oldprio = $coroutine->prio ($newprio) |
583 | =item $oldprio = $coro->prio ($newprio) |
416 | |
584 | |
417 | Sets (or gets, if the argument is missing) the priority of the |
585 | Sets (or gets, if the argument is missing) the priority of the |
418 | coroutine. Higher priority coroutines get run before lower priority |
586 | coro. Higher priority coro get run before lower priority |
419 | coroutines. Priorities are small signed integers (currently -4 .. +3), |
587 | coro. Priorities are small signed integers (currently -4 .. +3), |
420 | that you can refer to using PRIO_xxx constants (use the import tag :prio |
588 | that you can refer to using PRIO_xxx constants (use the import tag :prio |
421 | to get then): |
589 | to get then): |
422 | |
590 | |
423 | PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN |
591 | PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN |
424 | 3 > 1 > 0 > -1 > -3 > -4 |
592 | 3 > 1 > 0 > -1 > -3 > -4 |
425 | |
593 | |
426 | # set priority to HIGH |
594 | # set priority to HIGH |
427 | current->prio(PRIO_HIGH); |
595 | current->prio (PRIO_HIGH); |
428 | |
596 | |
429 | The idle coroutine ($Coro::idle) always has a lower priority than any |
597 | The idle coro ($Coro::idle) always has a lower priority than any |
430 | existing coroutine. |
598 | existing coro. |
431 | |
599 | |
432 | Changing the priority of the current coroutine will take effect immediately, |
600 | Changing the priority of the current coro will take effect immediately, |
433 | but changing the priority of coroutines in the ready queue (but not |
601 | but changing the priority of coro in the ready queue (but not |
434 | running) will only take effect after the next schedule (of that |
602 | running) will only take effect after the next schedule (of that |
435 | coroutine). This is a bug that will be fixed in some future version. |
603 | coro). This is a bug that will be fixed in some future version. |
436 | |
604 | |
437 | =item $newprio = $coroutine->nice ($change) |
605 | =item $newprio = $coro->nice ($change) |
438 | |
606 | |
439 | Similar to C<prio>, but subtract the given value from the priority (i.e. |
607 | Similar to C<prio>, but subtract the given value from the priority (i.e. |
440 | higher values mean lower priority, just as in unix). |
608 | higher values mean lower priority, just as in unix). |
441 | |
609 | |
442 | =item $olddesc = $coroutine->desc ($newdesc) |
610 | =item $olddesc = $coro->desc ($newdesc) |
443 | |
611 | |
444 | Sets (or gets in case the argument is missing) the description for this |
612 | Sets (or gets in case the argument is missing) the description for this |
445 | coroutine. This is just a free-form string you can associate with a coroutine. |
613 | coro. This is just a free-form string you can associate with a |
|
|
614 | coro. |
|
|
615 | |
|
|
616 | This method simply sets the C<< $coro->{desc} >> member to the given |
|
|
617 | string. You can modify this member directly if you wish. |
446 | |
618 | |
447 | =cut |
619 | =cut |
448 | |
620 | |
449 | sub desc { |
621 | sub desc { |
450 | my $old = $_[0]{desc}; |
622 | my $old = $_[0]{desc}; |
451 | $_[0]{desc} = $_[1] if @_ > 1; |
623 | $_[0]{desc} = $_[1] if @_ > 1; |
452 | $old; |
624 | $old; |
453 | } |
625 | } |
454 | |
626 | |
|
|
627 | sub transfer { |
|
|
628 | require Carp; |
|
|
629 | Carp::croak ("You must not call ->transfer on Coro objects. Use Coro::State objects or the ->schedule_to method. Caught"); |
|
|
630 | } |
|
|
631 | |
455 | =back |
632 | =back |
456 | |
633 | |
457 | =head2 GLOBAL FUNCTIONS |
634 | =head1 GLOBAL FUNCTIONS |
458 | |
635 | |
459 | =over 4 |
636 | =over 4 |
460 | |
637 | |
461 | =item Coro::nready |
638 | =item Coro::nready |
462 | |
639 | |
463 | Returns the number of coroutines that are currently in the ready state, |
640 | Returns the number of coro that are currently in the ready state, |
464 | i.e. that can be swicthed to. The value C<0> means that the only runnable |
641 | i.e. that can be switched to by calling C<schedule> directory or |
|
|
642 | indirectly. The value C<0> means that the only runnable coro is the |
465 | coroutine is the currently running one, so C<cede> would have no effect, |
643 | currently running one, so C<cede> would have no effect, and C<schedule> |
466 | and C<schedule> would cause a deadlock unless there is an idle handler |
644 | would cause a deadlock unless there is an idle handler that wakes up some |
467 | that wakes up some coroutines. |
645 | coro. |
468 | |
646 | |
469 | =item my $guard = Coro::guard { ... } |
647 | =item my $guard = Coro::guard { ... } |
470 | |
648 | |
471 | This creates and returns a guard object. Nothing happens until the object |
649 | This function still exists, but is deprecated. Please use the |
472 | gets destroyed, in which case the codeblock given as argument will be |
650 | C<Guard::guard> function instead. |
473 | executed. This is useful to free locks or other resources in case of a |
|
|
474 | runtime error or when the coroutine gets canceled, as in both cases the |
|
|
475 | guard block will be executed. The guard object supports only one method, |
|
|
476 | C<< ->cancel >>, which will keep the codeblock from being executed. |
|
|
477 | |
651 | |
478 | Example: set some flag and clear it again when the coroutine gets canceled |
|
|
479 | or the function returns: |
|
|
480 | |
|
|
481 | sub do_something { |
|
|
482 | my $guard = Coro::guard { $busy = 0 }; |
|
|
483 | $busy = 1; |
|
|
484 | |
|
|
485 | # do something that requires $busy to be true |
|
|
486 | } |
|
|
487 | |
|
|
488 | =cut |
652 | =cut |
489 | |
653 | |
490 | sub guard(&) { |
654 | BEGIN { *guard = \&Guard::guard } |
491 | bless \(my $cb = $_[0]), "Coro::guard" |
|
|
492 | } |
|
|
493 | |
|
|
494 | sub Coro::guard::cancel { |
|
|
495 | ${$_[0]} = sub { }; |
|
|
496 | } |
|
|
497 | |
|
|
498 | sub Coro::guard::DESTROY { |
|
|
499 | ${$_[0]}->(); |
|
|
500 | } |
|
|
501 | |
|
|
502 | |
655 | |
503 | =item unblock_sub { ... } |
656 | =item unblock_sub { ... } |
504 | |
657 | |
505 | This utility function takes a BLOCK or code reference and "unblocks" it, |
658 | This utility function takes a BLOCK or code reference and "unblocks" it, |
506 | returning the new coderef. This means that the new coderef will return |
659 | returning a new coderef. Unblocking means that calling the new coderef |
507 | immediately without blocking, returning nothing, while the original code |
660 | will return immediately without blocking, returning nothing, while the |
508 | ref will be called (with parameters) from within its own coroutine. |
661 | original code ref will be called (with parameters) from within another |
|
|
662 | coro. |
509 | |
663 | |
510 | The reason this fucntion exists is that many event libraries (such as the |
664 | The reason this function exists is that many event libraries (such as the |
511 | venerable L<Event|Event> module) are not coroutine-safe (a weaker form |
665 | venerable L<Event|Event> module) are not thread-safe (a weaker form |
512 | of thread-safety). This means you must not block within event callbacks, |
666 | of reentrancy). This means you must not block within event callbacks, |
513 | otherwise you might suffer from crashes or worse. |
667 | otherwise you might suffer from crashes or worse. The only event library |
|
|
668 | currently known that is safe to use without C<unblock_sub> is L<EV>. |
514 | |
669 | |
515 | This function allows your callbacks to block by executing them in another |
670 | This function allows your callbacks to block by executing them in another |
516 | coroutine where it is safe to block. One example where blocking is handy |
671 | coro where it is safe to block. One example where blocking is handy |
517 | is when you use the L<Coro::AIO|Coro::AIO> functions to save results to |
672 | is when you use the L<Coro::AIO|Coro::AIO> functions to save results to |
518 | disk. |
673 | disk, for example. |
519 | |
674 | |
520 | In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when |
675 | In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when |
521 | creating event callbacks that want to block. |
676 | creating event callbacks that want to block. |
|
|
677 | |
|
|
678 | If your handler does not plan to block (e.g. simply sends a message to |
|
|
679 | another coro, or puts some other coro into the ready queue), there is |
|
|
680 | no reason to use C<unblock_sub>. |
|
|
681 | |
|
|
682 | Note that you also need to use C<unblock_sub> for any other callbacks that |
|
|
683 | are indirectly executed by any C-based event loop. For example, when you |
|
|
684 | use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it |
|
|
685 | provides callbacks that are the result of some event callback, then you |
|
|
686 | must not block either, or use C<unblock_sub>. |
522 | |
687 | |
523 | =cut |
688 | =cut |
524 | |
689 | |
525 | our @unblock_queue; |
690 | our @unblock_queue; |
526 | |
691 | |
527 | # we create a special coro because we want to cede, |
692 | # we create a special coro because we want to cede, |
528 | # to reduce pressure on the coro pool (because most callbacks |
693 | # to reduce pressure on the coro pool (because most callbacks |
529 | # return immediately and can be reused) and because we cannot cede |
694 | # return immediately and can be reused) and because we cannot cede |
530 | # inside an event callback. |
695 | # inside an event callback. |
531 | our $unblock_scheduler = async { |
696 | our $unblock_scheduler = new Coro sub { |
532 | while () { |
697 | while () { |
533 | while (my $cb = pop @unblock_queue) { |
698 | while (my $cb = pop @unblock_queue) { |
534 | # this is an inlined copy of async_pool |
699 | &async_pool (@$cb); |
535 | my $coro = (pop @pool or new Coro \&pool_handler); |
|
|
536 | |
700 | |
537 | $coro->{_invoke} = $cb; |
|
|
538 | $coro->ready; |
|
|
539 | cede; # for short-lived callbacks, this reduces pressure on the coro pool |
701 | # for short-lived callbacks, this reduces pressure on the coro pool |
|
|
702 | # as the chance is very high that the async_poll coro will be back |
|
|
703 | # in the idle state when cede returns |
|
|
704 | cede; |
540 | } |
705 | } |
541 | schedule; # sleep well |
706 | schedule; # sleep well |
542 | } |
707 | } |
543 | }; |
708 | }; |
|
|
709 | $unblock_scheduler->{desc} = "[unblock_sub scheduler]"; |
544 | |
710 | |
545 | sub unblock_sub(&) { |
711 | sub unblock_sub(&) { |
546 | my $cb = shift; |
712 | my $cb = shift; |
547 | |
713 | |
548 | sub { |
714 | sub { |
549 | unshift @unblock_queue, [$cb, @_]; |
715 | unshift @unblock_queue, [$cb, @_]; |
550 | $unblock_scheduler->ready; |
716 | $unblock_scheduler->ready; |
551 | } |
717 | } |
552 | } |
718 | } |
553 | |
719 | |
|
|
720 | =item $cb = rouse_cb |
|
|
721 | |
|
|
722 | Create and return a "rouse callback". That's a code reference that, |
|
|
723 | when called, will remember a copy of its arguments and notify the owner |
|
|
724 | coro of the callback. |
|
|
725 | |
|
|
726 | See the next function. |
|
|
727 | |
|
|
728 | =item @args = rouse_wait [$cb] |
|
|
729 | |
|
|
730 | Wait for the specified rouse callback (or the last one that was created in |
|
|
731 | this coro). |
|
|
732 | |
|
|
733 | As soon as the callback is invoked (or when the callback was invoked |
|
|
734 | before C<rouse_wait>), it will return the arguments originally passed to |
|
|
735 | the rouse callback. In scalar context, that means you get the I<last> |
|
|
736 | argument, just as if C<rouse_wait> had a C<return ($a1, $a2, $a3...)> |
|
|
737 | statement at the end. |
|
|
738 | |
|
|
739 | See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example. |
|
|
740 | |
554 | =back |
741 | =back |
555 | |
742 | |
556 | =cut |
743 | =cut |
557 | |
744 | |
558 | 1; |
745 | 1; |
559 | |
746 | |
|
|
747 | =head1 HOW TO WAIT FOR A CALLBACK |
|
|
748 | |
|
|
749 | It is very common for a coro to wait for some callback to be |
|
|
750 | called. This occurs naturally when you use coro in an otherwise |
|
|
751 | event-based program, or when you use event-based libraries. |
|
|
752 | |
|
|
753 | These typically register a callback for some event, and call that callback |
|
|
754 | when the event occured. In a coro, however, you typically want to |
|
|
755 | just wait for the event, simplyifying things. |
|
|
756 | |
|
|
757 | For example C<< AnyEvent->child >> registers a callback to be called when |
|
|
758 | a specific child has exited: |
|
|
759 | |
|
|
760 | my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... }); |
|
|
761 | |
|
|
762 | But from within a coro, you often just want to write this: |
|
|
763 | |
|
|
764 | my $status = wait_for_child $pid; |
|
|
765 | |
|
|
766 | Coro offers two functions specifically designed to make this easy, |
|
|
767 | C<Coro::rouse_cb> and C<Coro::rouse_wait>. |
|
|
768 | |
|
|
769 | The first function, C<rouse_cb>, generates and returns a callback that, |
|
|
770 | when invoked, will save its arguments and notify the coro that |
|
|
771 | created the callback. |
|
|
772 | |
|
|
773 | The second function, C<rouse_wait>, waits for the callback to be called |
|
|
774 | (by calling C<schedule> to go to sleep) and returns the arguments |
|
|
775 | originally passed to the callback. |
|
|
776 | |
|
|
777 | Using these functions, it becomes easy to write the C<wait_for_child> |
|
|
778 | function mentioned above: |
|
|
779 | |
|
|
780 | sub wait_for_child($) { |
|
|
781 | my ($pid) = @_; |
|
|
782 | |
|
|
783 | my $watcher = AnyEvent->child (pid => $pid, cb => Coro::rouse_cb); |
|
|
784 | |
|
|
785 | my ($rpid, $rstatus) = Coro::rouse_wait; |
|
|
786 | $rstatus |
|
|
787 | } |
|
|
788 | |
|
|
789 | In the case where C<rouse_cb> and C<rouse_wait> are not flexible enough, |
|
|
790 | you can roll your own, using C<schedule>: |
|
|
791 | |
|
|
792 | sub wait_for_child($) { |
|
|
793 | my ($pid) = @_; |
|
|
794 | |
|
|
795 | # store the current coro in $current, |
|
|
796 | # and provide result variables for the closure passed to ->child |
|
|
797 | my $current = $Coro::current; |
|
|
798 | my ($done, $rstatus); |
|
|
799 | |
|
|
800 | # pass a closure to ->child |
|
|
801 | my $watcher = AnyEvent->child (pid => $pid, cb => sub { |
|
|
802 | $rstatus = $_[1]; # remember rstatus |
|
|
803 | $done = 1; # mark $rstatus as valud |
|
|
804 | }); |
|
|
805 | |
|
|
806 | # wait until the closure has been called |
|
|
807 | schedule while !$done; |
|
|
808 | |
|
|
809 | $rstatus |
|
|
810 | } |
|
|
811 | |
|
|
812 | |
560 | =head1 BUGS/LIMITATIONS |
813 | =head1 BUGS/LIMITATIONS |
561 | |
814 | |
562 | - you must make very sure that no coro is still active on global |
815 | =over 4 |
563 | destruction. very bad things might happen otherwise (usually segfaults). |
|
|
564 | |
816 | |
|
|
817 | =item fork with pthread backend |
|
|
818 | |
|
|
819 | When Coro is compiled using the pthread backend (which isn't recommended |
|
|
820 | but required on many BSDs as their libcs are completely broken), then |
|
|
821 | coro will not survive a fork. There is no known workaround except to |
|
|
822 | fix your libc and use a saner backend. |
|
|
823 | |
|
|
824 | =item perl process emulation ("threads") |
|
|
825 | |
565 | - this module is not thread-safe. You should only ever use this module |
826 | This module is not perl-pseudo-thread-safe. You should only ever use this |
566 | from the same thread (this requirement might be losened in the future |
827 | module from the first thread (this requirement might be removed in the |
567 | to allow per-thread schedulers, but Coro::State does not yet allow |
828 | future to allow per-thread schedulers, but Coro::State does not yet allow |
568 | this). |
829 | this). I recommend disabling thread support and using processes, as having |
|
|
830 | the windows process emulation enabled under unix roughly halves perl |
|
|
831 | performance, even when not used. |
|
|
832 | |
|
|
833 | =item coro switching is not signal safe |
|
|
834 | |
|
|
835 | You must not switch to another coro from within a signal handler (only |
|
|
836 | relevant with %SIG - most event libraries provide safe signals), I<unless> |
|
|
837 | you are sure you are not interrupting a Coro function. |
|
|
838 | |
|
|
839 | That means you I<MUST NOT> call any function that might "block" the |
|
|
840 | current coro - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or |
|
|
841 | anything that calls those. Everything else, including calling C<ready>, |
|
|
842 | works. |
|
|
843 | |
|
|
844 | =back |
|
|
845 | |
|
|
846 | |
|
|
847 | =head1 WINDOWS PROCESS EMULATION |
|
|
848 | |
|
|
849 | A great many people seem to be confused about ithreads (for example, Chip |
|
|
850 | Salzenberg called me unintelligent, incapable, stupid and gullible, |
|
|
851 | while in the same mail making rather confused statements about perl |
|
|
852 | ithreads (for example, that memory or files would be shared), showing his |
|
|
853 | lack of understanding of this area - if it is hard to understand for Chip, |
|
|
854 | it is probably not obvious to everybody). |
|
|
855 | |
|
|
856 | What follows is an ultra-condensed version of my talk about threads in |
|
|
857 | scripting languages given onthe perl workshop 2009: |
|
|
858 | |
|
|
859 | The so-called "ithreads" were originally implemented for two reasons: |
|
|
860 | first, to (badly) emulate unix processes on native win32 perls, and |
|
|
861 | secondly, to replace the older, real thread model ("5.005-threads"). |
|
|
862 | |
|
|
863 | It does that by using threads instead of OS processes. The difference |
|
|
864 | between processes and threads is that threads share memory (and other |
|
|
865 | state, such as files) between threads within a single process, while |
|
|
866 | processes do not share anything (at least not semantically). That |
|
|
867 | means that modifications done by one thread are seen by others, while |
|
|
868 | modifications by one process are not seen by other processes. |
|
|
869 | |
|
|
870 | The "ithreads" work exactly like that: when creating a new ithreads |
|
|
871 | process, all state is copied (memory is copied physically, files and code |
|
|
872 | is copied logically). Afterwards, it isolates all modifications. On UNIX, |
|
|
873 | the same behaviour can be achieved by using operating system processes, |
|
|
874 | except that UNIX typically uses hardware built into the system to do this |
|
|
875 | efficiently, while the windows process emulation emulates this hardware in |
|
|
876 | software (rather efficiently, but of course it is still much slower than |
|
|
877 | dedicated hardware). |
|
|
878 | |
|
|
879 | As mentioned before, loading code, modifying code, modifying data |
|
|
880 | structures and so on is only visible in the ithreads process doing the |
|
|
881 | modification, not in other ithread processes within the same OS process. |
|
|
882 | |
|
|
883 | This is why "ithreads" do not implement threads for perl at all, only |
|
|
884 | processes. What makes it so bad is that on non-windows platforms, you can |
|
|
885 | actually take advantage of custom hardware for this purpose (as evidenced |
|
|
886 | by the forks module, which gives you the (i-) threads API, just much |
|
|
887 | faster). |
|
|
888 | |
|
|
889 | Sharing data is in the i-threads model is done by transfering data |
|
|
890 | structures between threads using copying semantics, which is very slow - |
|
|
891 | shared data simply does not exist. Benchmarks using i-threads which are |
|
|
892 | communication-intensive show extremely bad behaviour with i-threads (in |
|
|
893 | fact, so bad that Coro, which cannot take direct advantage of multiple |
|
|
894 | CPUs, is often orders of magnitude faster because it shares data using |
|
|
895 | real threads, refer to my talk for details). |
|
|
896 | |
|
|
897 | As summary, i-threads *use* threads to implement processes, while |
|
|
898 | the compatible forks module *uses* processes to emulate, uhm, |
|
|
899 | processes. I-threads slow down every perl program when enabled, and |
|
|
900 | outside of windows, serve no (or little) practical purpose, but |
|
|
901 | disadvantages every single-threaded Perl program. |
|
|
902 | |
|
|
903 | This is the reason that I try to avoid the name "ithreads", as it is |
|
|
904 | misleading as it implies that it implements some kind of thread model for |
|
|
905 | perl, and prefer the name "windows process emulation", which describes the |
|
|
906 | actual use and behaviour of it much better. |
569 | |
907 | |
570 | =head1 SEE ALSO |
908 | =head1 SEE ALSO |
571 | |
909 | |
|
|
910 | Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>. |
|
|
911 | |
|
|
912 | Debugging: L<Coro::Debug>. |
|
|
913 | |
572 | Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>. |
914 | Support/Utility: L<Coro::Specific>, L<Coro::Util>. |
573 | |
915 | |
574 | Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>. |
916 | Locking and IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, |
|
|
917 | L<Coro::SemaphoreSet>, L<Coro::RWLock>. |
575 | |
918 | |
576 | Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>. |
919 | I/O and Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>. |
577 | |
920 | |
578 | Embedding: L<Coro:MakeMaker> |
921 | Compatibility with other modules: L<Coro::LWP> (but see also L<AnyEvent::HTTP> for |
|
|
922 | a better-working alternative), L<Coro::BDB>, L<Coro::Storable>, |
|
|
923 | L<Coro::Select>. |
|
|
924 | |
|
|
925 | XS API: L<Coro::MakeMaker>. |
|
|
926 | |
|
|
927 | Low level Configuration, Thread Environment, Continuations: L<Coro::State>. |
579 | |
928 | |
580 | =head1 AUTHOR |
929 | =head1 AUTHOR |
581 | |
930 | |
582 | Marc Lehmann <schmorp@schmorp.de> |
931 | Marc Lehmann <schmorp@schmorp.de> |
583 | http://home.schmorp.de/ |
932 | http://home.schmorp.de/ |