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 process 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 to |
31 | For a tutorial-style introduction, please read the L<Coro::Intro> |
24 | threads but don't run in parallel. |
32 | manpage. This manpage mainly contains reference information. |
25 | |
33 | |
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34 | This module collection manages continuations in general, most often in |
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35 | the form of cooperative threads (also called coros, or simply "coro" |
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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. |
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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 | |
26 | In this module, coroutines are defined as "callchain + lexical variables |
60 | In this module, a thread is defined as "callchain + lexical variables + |
27 | + @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own |
61 | some package variables + C stack), that is, a thread has its own callchain, |
28 | callchain, it's own set of lexicals and it's own set of perl's most |
62 | its own set of lexicals and its own set of perls most important global |
29 | important global 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. |
30 | |
67 | |
31 | =cut |
68 | =cut |
32 | |
69 | |
33 | package Coro; |
70 | package Coro; |
34 | |
71 | |
35 | use strict; |
72 | use common::sense; |
36 | no warnings "uninitialized"; |
73 | |
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74 | use Carp (); |
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75 | |
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76 | use Guard (); |
37 | |
77 | |
38 | use Coro::State; |
78 | use Coro::State; |
39 | |
79 | |
40 | use base Exporter::; |
80 | use base qw(Coro::State Exporter); |
41 | |
81 | |
42 | our $idle; # idle coroutine |
82 | our $idle; # idle handler |
43 | our $main; # main coroutine |
83 | our $main; # main coro |
44 | our $current; # current coroutine |
84 | our $current; # current coro |
45 | |
85 | |
46 | our $VERSION = 1.6; |
86 | our $VERSION = 5.25; |
47 | |
87 | |
48 | our @EXPORT = qw(async cede schedule terminate current); |
88 | our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub rouse_cb rouse_wait); |
49 | our %EXPORT_TAGS = ( |
89 | our %EXPORT_TAGS = ( |
50 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
90 | prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)], |
51 | ); |
91 | ); |
52 | our @EXPORT_OK = @{$EXPORT_TAGS{prio}}; |
92 | our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready)); |
53 | |
93 | |
54 | { |
94 | =head1 GLOBAL VARIABLES |
55 | my @async; |
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56 | my $init; |
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57 | |
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58 | # this way of handling attributes simply is NOT scalable ;() |
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59 | sub import { |
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60 | no strict 'refs'; |
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61 | |
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62 | Coro->export_to_level(1, @_); |
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63 | |
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64 | my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE}; |
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65 | *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub { |
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66 | my ($package, $ref) = (shift, shift); |
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67 | my @attrs; |
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68 | for (@_) { |
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69 | if ($_ eq "Coro") { |
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70 | push @async, $ref; |
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71 | unless ($init++) { |
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72 | eval q{ |
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73 | sub INIT { |
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74 | &async(pop @async) while @async; |
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75 | } |
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76 | }; |
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77 | } |
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78 | } else { |
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79 | push @attrs, $_; |
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80 | } |
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81 | } |
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82 | return $old ? $old->($package, $ref, @attrs) : @attrs; |
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83 | }; |
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84 | } |
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85 | |
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86 | } |
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87 | |
95 | |
88 | =over 4 |
96 | =over 4 |
89 | |
97 | |
90 | =item $main |
98 | =item $Coro::main |
91 | |
99 | |
92 | This coroutine represents the main program. |
100 | This variable stores the Coro object that represents the main |
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101 | program. While you cna C<ready> it and do most other things you can do to |
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102 | coro, it is mainly useful to compare again C<$Coro::current>, to see |
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103 | whether you are running in the main program or not. |
93 | |
104 | |
94 | =cut |
105 | =cut |
95 | |
106 | |
96 | $main = new Coro; |
107 | # $main is now being initialised by Coro::State |
97 | |
108 | |
98 | =item $current (or as function: current) |
109 | =item $Coro::current |
99 | |
110 | |
100 | The current coroutine (the last coroutine switched to). The initial value is C<$main> (of course). |
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 |
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113 | C<$Coro::main> (of course). |
101 | |
114 | |
102 | =cut |
115 | This variable is B<strictly> I<read-only>. You can take copies of the |
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116 | value stored in it and use it as any other Coro object, but you must |
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117 | not otherwise modify the variable itself. |
103 | |
118 | |
104 | # maybe some other module used Coro::Specific before... |
119 | =cut |
105 | if ($current) { |
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106 | $main->{specific} = $current->{specific}; |
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107 | } |
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108 | |
120 | |
109 | $current = $main; |
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110 | |
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111 | sub current() { $current } |
121 | sub current() { $current } # [DEPRECATED] |
112 | |
122 | |
113 | =item $idle |
123 | =item $Coro::idle |
114 | |
124 | |
115 | The coroutine to switch to when no other coroutine is running. The default |
125 | This variable is mainly useful to integrate Coro into event loops. It is |
116 | implementation prints "FATAL: deadlock detected" and exits. |
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. |
117 | |
128 | |
118 | =cut |
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). |
119 | |
131 | |
120 | # should be done using priorities :( |
132 | The default implementation dies with "FATAL: deadlock detected.", followed |
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133 | by a thread listing, because the program has no other way to continue. |
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134 | |
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135 | This hook is overwritten by modules such as C<Coro::EV> and |
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136 | C<Coro::AnyEvent> to wait on an external event that hopefully wake up a |
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137 | coro so the scheduler can run it. |
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138 | |
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139 | See L<Coro::EV> or L<Coro::AnyEvent> for examples of using this technique. |
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140 | |
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141 | =cut |
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142 | |
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143 | # ||= because other modules could have provided their own by now |
121 | $idle = new Coro sub { |
144 | $idle ||= new Coro sub { |
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145 | require Coro::Debug; |
122 | print STDERR "FATAL: deadlock detected\n"; |
146 | die "FATAL: deadlock detected.\n" |
123 | exit(51); |
147 | . Coro::Debug::ps_listing (); |
124 | }; |
148 | }; |
125 | |
149 | |
126 | # this coroutine is necessary because a coroutine |
150 | # this coro is necessary because a coro |
127 | # cannot destroy itself. |
151 | # cannot destroy itself. |
128 | my @destroy; |
152 | our @destroy; |
129 | my $manager; |
153 | our $manager; |
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154 | |
130 | $manager = new Coro sub { |
155 | $manager = new Coro sub { |
131 | while () { |
156 | while () { |
132 | # by overwriting the state object with the manager we destroy it |
157 | Coro::State::cancel shift @destroy |
133 | # while still being able to schedule this coroutine (in case it has |
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134 | # been readied multiple times. this is harmless since the manager |
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135 | # can be called as many times as neccessary and will always |
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136 | # remove itself from the runqueue |
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137 | while (@destroy) { |
158 | while @destroy; |
138 | my $coro = pop @destroy; |
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139 | $coro->{status} ||= []; |
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140 | $_->ready for @{delete $coro->{join} || []}; |
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141 | |
159 | |
142 | # the next line destroys the _coro_state, but keeps the |
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143 | # process itself intact (we basically make it a zombie |
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144 | # process that always runs the manager thread, so it's possible |
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145 | # to transfer() to this process). |
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146 | $coro->{_coro_state} = $manager->{_coro_state}; |
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147 | } |
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148 | &schedule; |
160 | &schedule; |
149 | } |
161 | } |
150 | }; |
162 | }; |
151 | |
163 | $manager->{desc} = "[coro manager]"; |
152 | # static methods. not really. |
164 | $manager->prio (PRIO_MAX); |
153 | |
165 | |
154 | =back |
166 | =back |
155 | |
167 | |
156 | =head2 STATIC METHODS |
168 | =head1 SIMPLE CORO CREATION |
157 | |
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158 | Static methods are actually functions that operate on the current process only. |
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159 | |
169 | |
160 | =over 4 |
170 | =over 4 |
161 | |
171 | |
162 | =item async { ... } [@args...] |
172 | =item async { ... } [@args...] |
163 | |
173 | |
164 | Create a new asynchronous process and return it's process object |
174 | Create a new coro and return its Coro object (usually |
165 | (usually unused). When the sub returns the new process is automatically |
175 | unused). The coro will be put into the ready queue, so |
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176 | it will start running automatically on the next scheduler run. |
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177 | |
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178 | The first argument is a codeblock/closure that should be executed in the |
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179 | coro. When it returns argument returns the coro is automatically |
166 | terminated. |
180 | terminated. |
167 | |
181 | |
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182 | The remaining arguments are passed as arguments to the closure. |
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183 | |
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184 | See the C<Coro::State::new> constructor for info about the coro |
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185 | environment in which coro are executed. |
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186 | |
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187 | Calling C<exit> in a coro will do the same as calling exit outside |
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188 | the coro. Likewise, when the coro dies, the program will exit, |
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189 | just as it would in the main program. |
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190 | |
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191 | If you do not want that, you can provide a default C<die> handler, or |
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192 | simply avoid dieing (by use of C<eval>). |
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193 | |
168 | # create a new coroutine that just prints its arguments |
194 | Example: Create a new coro that just prints its arguments. |
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195 | |
169 | async { |
196 | async { |
170 | print "@_\n"; |
197 | print "@_\n"; |
171 | } 1,2,3,4; |
198 | } 1,2,3,4; |
172 | |
199 | |
173 | =cut |
200 | =item async_pool { ... } [@args...] |
174 | |
201 | |
175 | sub async(&@) { |
202 | Similar to C<async>, but uses a coro pool, so you should not call |
176 | my $pid = new Coro @_; |
203 | terminate or join on it (although you are allowed to), and you get a |
177 | $manager->ready; # this ensures that the stack is cloned from the manager |
204 | coro that might have executed other code already (which can be good |
178 | $pid->ready; |
205 | or bad :). |
179 | $pid; |
206 | |
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207 | On the plus side, this function is about twice as fast as creating (and |
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208 | destroying) a completely new coro, so if you need a lot of generic |
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209 | coros in quick successsion, use C<async_pool>, not C<async>. |
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210 | |
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211 | The code block is executed in an C<eval> context and a warning will be |
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212 | issued in case of an exception instead of terminating the program, as |
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213 | C<async> does. As the coro is being reused, stuff like C<on_destroy> |
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214 | will not work in the expected way, unless you call terminate or cancel, |
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215 | which somehow defeats the purpose of pooling (but is fine in the |
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216 | exceptional case). |
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217 | |
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218 | The priority will be reset to C<0> after each run, tracing will be |
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219 | disabled, the description will be reset and the default output filehandle |
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220 | gets restored, so you can change all these. Otherwise the coro will |
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221 | be re-used "as-is": most notably if you change other per-coro global |
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222 | stuff such as C<$/> you I<must needs> revert that change, which is most |
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223 | simply done by using local as in: C<< local $/ >>. |
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224 | |
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225 | The idle pool size is limited to C<8> idle coros (this can be |
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226 | adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle |
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227 | coros as required. |
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228 | |
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229 | If you are concerned about pooled coros growing a lot because a |
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230 | single C<async_pool> used a lot of stackspace you can e.g. C<async_pool |
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231 | { terminate }> once per second or so to slowly replenish the pool. In |
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232 | addition to that, when the stacks used by a handler grows larger than 32kb |
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233 | (adjustable via $Coro::POOL_RSS) it will also be destroyed. |
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234 | |
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235 | =cut |
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236 | |
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237 | our $POOL_SIZE = 8; |
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238 | our $POOL_RSS = 32 * 1024; |
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239 | our @async_pool; |
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240 | |
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241 | sub pool_handler { |
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242 | while () { |
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243 | eval { |
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244 | &{&_pool_handler} while 1; |
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245 | }; |
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246 | |
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247 | warn $@ if $@; |
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248 | } |
180 | } |
249 | } |
181 | |
250 | |
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251 | =back |
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252 | |
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253 | =head1 STATIC METHODS |
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254 | |
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255 | Static methods are actually functions that implicitly operate on the |
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256 | current coro. |
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257 | |
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258 | =over 4 |
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259 | |
182 | =item schedule |
260 | =item schedule |
183 | |
261 | |
184 | Calls the scheduler. Please note that the current process will not be put |
262 | Calls the scheduler. The scheduler will find the next coro that is |
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263 | to be run from the ready queue and switches to it. The next coro |
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264 | to be run is simply the one with the highest priority that is longest |
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265 | in its ready queue. If there is no coro ready, it will call the |
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266 | C<$Coro::idle> hook. |
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267 | |
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268 | Please note that the current coro will I<not> be put into the ready |
185 | into the ready queue, so calling this function usually means you will |
269 | queue, so calling this function usually means you will never be called |
186 | never be called again. |
270 | again unless something else (e.g. an event handler) calls C<< ->ready >>, |
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271 | thus waking you up. |
187 | |
272 | |
188 | =cut |
273 | This makes C<schedule> I<the> generic method to use to block the current |
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274 | coro and wait for events: first you remember the current coro in |
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275 | a variable, then arrange for some callback of yours to call C<< ->ready |
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276 | >> on that once some event happens, and last you call C<schedule> to put |
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277 | yourself to sleep. Note that a lot of things can wake your coro up, |
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278 | so you need to check whether the event indeed happened, e.g. by storing the |
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279 | status in a variable. |
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280 | |
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281 | See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks. |
189 | |
282 | |
190 | =item cede |
283 | =item cede |
191 | |
284 | |
192 | "Cede" to other processes. This function puts the current process into the |
285 | "Cede" to other coros. This function puts the current coro into |
193 | ready queue and calls C<schedule>, which has the effect of giving up the |
286 | the ready queue and calls C<schedule>, which has the effect of giving |
194 | current "timeslice" to other coroutines of the same or higher priority. |
287 | up the current "timeslice" to other coros of the same or higher |
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288 | priority. Once your coro gets its turn again it will automatically be |
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289 | resumed. |
195 | |
290 | |
196 | =cut |
291 | This function is often called C<yield> in other languages. |
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292 | |
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293 | =item Coro::cede_notself |
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294 | |
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295 | Works like cede, but is not exported by default and will cede to I<any> |
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296 | coro, regardless of priority. This is useful sometimes to ensure |
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297 | progress is made. |
197 | |
298 | |
198 | =item terminate [arg...] |
299 | =item terminate [arg...] |
199 | |
300 | |
200 | Terminates the current process with the given status values (see L<cancel>). |
301 | Terminates the current coro with the given status values (see L<cancel>). |
201 | |
302 | |
202 | =cut |
303 | =item Coro::on_enter BLOCK, Coro::on_leave BLOCK |
203 | |
304 | |
204 | sub terminate { |
305 | These function install enter and leave winders in the current scope. The |
205 | $current->cancel (@_); |
306 | enter block will be executed when on_enter is called and whenever the |
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307 | current coro is re-entered by the scheduler, while the leave block is |
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308 | executed whenever the current coro is blocked by the scheduler, and |
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309 | also when the containing scope is exited (by whatever means, be it exit, |
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310 | die, last etc.). |
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311 | |
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312 | I<Neither invoking the scheduler, nor exceptions, are allowed within those |
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313 | BLOCKs>. That means: do not even think about calling C<die> without an |
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314 | eval, and do not even think of entering the scheduler in any way. |
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315 | |
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316 | Since both BLOCKs are tied to the current scope, they will automatically |
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317 | be removed when the current scope exits. |
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318 | |
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319 | These functions implement the same concept as C<dynamic-wind> in scheme |
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320 | does, and are useful when you want to localise some resource to a specific |
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321 | coro. |
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322 | |
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323 | They slow down thread switching considerably for coros that use them |
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324 | (about 40% for a BLOCK with a single assignment, so thread switching is |
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325 | still reasonably fast if the handlers are fast). |
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326 | |
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327 | These functions are best understood by an example: The following function |
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328 | will change the current timezone to "Antarctica/South_Pole", which |
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329 | requires a call to C<tzset>, but by using C<on_enter> and C<on_leave>, |
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330 | which remember/change the current timezone and restore the previous |
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331 | value, respectively, the timezone is only changed for the coro that |
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332 | installed those handlers. |
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333 | |
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334 | use POSIX qw(tzset); |
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335 | |
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336 | async { |
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337 | my $old_tz; # store outside TZ value here |
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338 | |
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339 | Coro::on_enter { |
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340 | $old_tz = $ENV{TZ}; # remember the old value |
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341 | |
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342 | $ENV{TZ} = "Antarctica/South_Pole"; |
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343 | tzset; # enable new value |
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344 | }; |
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345 | |
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346 | Coro::on_leave { |
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347 | $ENV{TZ} = $old_tz; |
|
|
348 | tzset; # restore old value |
|
|
349 | }; |
|
|
350 | |
|
|
351 | # at this place, the timezone is Antarctica/South_Pole, |
|
|
352 | # without disturbing the TZ of any other coro. |
|
|
353 | }; |
|
|
354 | |
|
|
355 | This can be used to localise about any resource (locale, uid, current |
|
|
356 | working directory etc.) to a block, despite the existance of other |
|
|
357 | coros. |
|
|
358 | |
|
|
359 | Another interesting example implements time-sliced multitasking using |
|
|
360 | interval timers (this could obviously be optimised, but does the job): |
|
|
361 | |
|
|
362 | # "timeslice" the given block |
|
|
363 | sub timeslice(&) { |
|
|
364 | use Time::HiRes (); |
|
|
365 | |
|
|
366 | Coro::on_enter { |
|
|
367 | # on entering the thread, we set an VTALRM handler to cede |
|
|
368 | $SIG{VTALRM} = sub { cede }; |
|
|
369 | # and then start the interval timer |
|
|
370 | Time::HiRes::setitimer &Time::HiRes::ITIMER_VIRTUAL, 0.01, 0.01; |
|
|
371 | }; |
|
|
372 | Coro::on_leave { |
|
|
373 | # on leaving the thread, we stop the interval timer again |
|
|
374 | Time::HiRes::setitimer &Time::HiRes::ITIMER_VIRTUAL, 0, 0; |
|
|
375 | }; |
|
|
376 | |
|
|
377 | &{+shift}; |
|
|
378 | } |
|
|
379 | |
|
|
380 | # use like this: |
|
|
381 | timeslice { |
|
|
382 | # The following is an endless loop that would normally |
|
|
383 | # monopolise the process. Since it runs in a timesliced |
|
|
384 | # environment, it will regularly cede to other threads. |
|
|
385 | while () { } |
|
|
386 | }; |
|
|
387 | |
|
|
388 | |
|
|
389 | =item killall |
|
|
390 | |
|
|
391 | Kills/terminates/cancels all coros except the currently running one. |
|
|
392 | |
|
|
393 | Note that while this will try to free some of the main interpreter |
|
|
394 | resources if the calling coro isn't the main coro, but one |
|
|
395 | cannot free all of them, so if a coro that is not the main coro |
|
|
396 | calls this function, there will be some one-time resource leak. |
|
|
397 | |
|
|
398 | =cut |
|
|
399 | |
|
|
400 | sub killall { |
|
|
401 | for (Coro::State::list) { |
|
|
402 | $_->cancel |
|
|
403 | if $_ != $current && UNIVERSAL::isa $_, "Coro"; |
|
|
404 | } |
206 | } |
405 | } |
207 | |
406 | |
208 | =back |
407 | =back |
209 | |
408 | |
210 | # dynamic methods |
409 | =head1 CORO OBJECT METHODS |
211 | |
410 | |
212 | =head2 PROCESS METHODS |
|
|
213 | |
|
|
214 | These are the methods you can call on process objects. |
411 | These are the methods you can call on coro objects (or to create |
|
|
412 | them). |
215 | |
413 | |
216 | =over 4 |
414 | =over 4 |
217 | |
415 | |
218 | =item new Coro \&sub [, @args...] |
416 | =item new Coro \&sub [, @args...] |
219 | |
417 | |
220 | Create a new process and return it. When the sub returns the process |
418 | Create a new coro and return it. When the sub returns, the coro |
221 | automatically terminates as if C<terminate> with the returned values were |
419 | automatically terminates as if C<terminate> with the returned values were |
222 | called. To make the process run you must first put it into the ready queue |
420 | called. To make the coro run you must first put it into the ready |
223 | by calling the ready method. |
421 | queue by calling the ready method. |
224 | |
422 | |
225 | =cut |
423 | See C<async> and C<Coro::State::new> for additional info about the |
|
|
424 | coro environment. |
226 | |
425 | |
|
|
426 | =cut |
|
|
427 | |
227 | sub _newcoro { |
428 | sub _coro_run { |
228 | terminate &{+shift}; |
429 | terminate &{+shift}; |
229 | } |
430 | } |
230 | |
431 | |
231 | sub new { |
432 | =item $success = $coro->ready |
232 | my $class = shift; |
|
|
233 | bless { |
|
|
234 | _coro_state => (new Coro::State $_[0] && \&_newcoro, @_), |
|
|
235 | }, $class; |
|
|
236 | } |
|
|
237 | |
433 | |
238 | =item $process->ready |
434 | Put the given coro into the end of its ready queue (there is one |
|
|
435 | queue for each priority) and return true. If the coro is already in |
|
|
436 | the ready queue, do nothing and return false. |
239 | |
437 | |
240 | Put the given process into the ready queue. |
438 | This ensures that the scheduler will resume this coro automatically |
|
|
439 | once all the coro of higher priority and all coro of the same |
|
|
440 | priority that were put into the ready queue earlier have been resumed. |
241 | |
441 | |
242 | =cut |
442 | =item $coro->suspend |
243 | |
443 | |
|
|
444 | Suspends the specified coro. A suspended coro works just like any other |
|
|
445 | coro, except that the scheduler will not select a suspended coro for |
|
|
446 | execution. |
|
|
447 | |
|
|
448 | Suspending a coro can be useful when you want to keep the coro from |
|
|
449 | running, but you don't want to destroy it, or when you want to temporarily |
|
|
450 | freeze a coro (e.g. for debugging) to resume it later. |
|
|
451 | |
|
|
452 | A scenario for the former would be to suspend all (other) coros after a |
|
|
453 | fork and keep them alive, so their destructors aren't called, but new |
|
|
454 | coros can be created. |
|
|
455 | |
|
|
456 | =item $coro->resume |
|
|
457 | |
|
|
458 | If the specified coro was suspended, it will be resumed. Note that when |
|
|
459 | the coro was in the ready queue when it was suspended, it might have been |
|
|
460 | unreadied by the scheduler, so an activation might have been lost. |
|
|
461 | |
|
|
462 | To avoid this, it is best to put a suspended coro into the ready queue |
|
|
463 | unconditionally, as every synchronisation mechanism must protect itself |
|
|
464 | against spurious wakeups, and the one in the Coro family certainly do |
|
|
465 | that. |
|
|
466 | |
|
|
467 | =item $is_ready = $coro->is_ready |
|
|
468 | |
|
|
469 | Returns true iff the Coro object is in the ready queue. Unless the Coro |
|
|
470 | object gets destroyed, it will eventually be scheduled by the scheduler. |
|
|
471 | |
|
|
472 | =item $is_running = $coro->is_running |
|
|
473 | |
|
|
474 | Returns true iff the Coro object is currently running. Only one Coro object |
|
|
475 | can ever be in the running state (but it currently is possible to have |
|
|
476 | multiple running Coro::States). |
|
|
477 | |
|
|
478 | =item $is_suspended = $coro->is_suspended |
|
|
479 | |
|
|
480 | Returns true iff this Coro object has been suspended. Suspended Coros will |
|
|
481 | not ever be scheduled. |
|
|
482 | |
244 | =item $process->cancel (arg...) |
483 | =item $coro->cancel (arg...) |
245 | |
484 | |
246 | Temrinates the given process and makes it return the given arguments as |
485 | Terminates the given Coro and makes it return the given arguments as |
247 | status (default: the empty list). |
486 | status (default: the empty list). Never returns if the Coro is the |
|
|
487 | current Coro. |
248 | |
488 | |
249 | =cut |
489 | =cut |
250 | |
490 | |
251 | sub cancel { |
491 | sub cancel { |
252 | my $self = shift; |
492 | my $self = shift; |
|
|
493 | |
|
|
494 | if ($current == $self) { |
|
|
495 | terminate @_; |
|
|
496 | } else { |
253 | $self->{status} = [@_]; |
497 | $self->{_status} = [@_]; |
254 | push @destroy, $self; |
498 | Coro::State::cancel $self; |
255 | $manager->ready; |
499 | } |
256 | &schedule if $current == $self; |
|
|
257 | } |
500 | } |
258 | |
501 | |
|
|
502 | =item $coro->schedule_to |
|
|
503 | |
|
|
504 | Puts the current coro to sleep (like C<Coro::schedule>), but instead |
|
|
505 | of continuing with the next coro from the ready queue, always switch to |
|
|
506 | the given coro object (regardless of priority etc.). The readyness |
|
|
507 | state of that coro isn't changed. |
|
|
508 | |
|
|
509 | This is an advanced method for special cases - I'd love to hear about any |
|
|
510 | uses for this one. |
|
|
511 | |
|
|
512 | =item $coro->cede_to |
|
|
513 | |
|
|
514 | Like C<schedule_to>, but puts the current coro into the ready |
|
|
515 | queue. This has the effect of temporarily switching to the given |
|
|
516 | coro, and continuing some time later. |
|
|
517 | |
|
|
518 | This is an advanced method for special cases - I'd love to hear about any |
|
|
519 | uses for this one. |
|
|
520 | |
|
|
521 | =item $coro->throw ([$scalar]) |
|
|
522 | |
|
|
523 | If C<$throw> is specified and defined, it will be thrown as an exception |
|
|
524 | inside the coro at the next convenient point in time. Otherwise |
|
|
525 | clears the exception object. |
|
|
526 | |
|
|
527 | Coro will check for the exception each time a schedule-like-function |
|
|
528 | returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down |
|
|
529 | >>, C<< Coro::Handle->readable >> and so on. Most of these functions |
|
|
530 | detect this case and return early in case an exception is pending. |
|
|
531 | |
|
|
532 | The exception object will be thrown "as is" with the specified scalar in |
|
|
533 | C<$@>, i.e. if it is a string, no line number or newline will be appended |
|
|
534 | (unlike with C<die>). |
|
|
535 | |
|
|
536 | This can be used as a softer means than C<cancel> to ask a coro to |
|
|
537 | end itself, although there is no guarantee that the exception will lead to |
|
|
538 | termination, and if the exception isn't caught it might well end the whole |
|
|
539 | program. |
|
|
540 | |
|
|
541 | You might also think of C<throw> as being the moral equivalent of |
|
|
542 | C<kill>ing a coro with a signal (in this case, a scalar). |
|
|
543 | |
259 | =item $process->join |
544 | =item $coro->join |
260 | |
545 | |
261 | Wait until the coroutine terminates and return any values given to the |
546 | Wait until the coro terminates and return any values given to the |
262 | C<terminate> or C<cancel> functions. C<join> can be called multiple times |
547 | C<terminate> or C<cancel> functions. C<join> can be called concurrently |
263 | from multiple processes. |
548 | from multiple coro, and all will be resumed and given the status |
|
|
549 | return once the C<$coro> terminates. |
264 | |
550 | |
265 | =cut |
551 | =cut |
266 | |
552 | |
267 | sub join { |
553 | sub join { |
268 | my $self = shift; |
554 | my $self = shift; |
|
|
555 | |
269 | unless ($self->{status}) { |
556 | unless ($self->{_status}) { |
270 | push @{$self->{join}}, $current; |
557 | my $current = $current; |
271 | &schedule; |
558 | |
|
|
559 | push @{$self->{_on_destroy}}, sub { |
|
|
560 | $current->ready; |
|
|
561 | undef $current; |
|
|
562 | }; |
|
|
563 | |
|
|
564 | &schedule while $current; |
272 | } |
565 | } |
|
|
566 | |
273 | wantarray ? @{$self->{status}} : $self->{status}[0]; |
567 | wantarray ? @{$self->{_status}} : $self->{_status}[0]; |
274 | } |
568 | } |
275 | |
569 | |
|
|
570 | =item $coro->on_destroy (\&cb) |
|
|
571 | |
|
|
572 | Registers a callback that is called when this coro gets destroyed, |
|
|
573 | but before it is joined. The callback gets passed the terminate arguments, |
|
|
574 | if any, and I<must not> die, under any circumstances. |
|
|
575 | |
|
|
576 | =cut |
|
|
577 | |
|
|
578 | sub on_destroy { |
|
|
579 | my ($self, $cb) = @_; |
|
|
580 | |
|
|
581 | push @{ $self->{_on_destroy} }, $cb; |
|
|
582 | } |
|
|
583 | |
276 | =item $oldprio = $process->prio($newprio) |
584 | =item $oldprio = $coro->prio ($newprio) |
277 | |
585 | |
278 | Sets (or gets, if the argument is missing) the priority of the |
586 | Sets (or gets, if the argument is missing) the priority of the |
279 | process. Higher priority processes get run before lower priority |
587 | coro. Higher priority coro get run before lower priority |
280 | processes. Priorities are small signed integers (currently -4 .. +3), |
588 | coro. Priorities are small signed integers (currently -4 .. +3), |
281 | that you can refer to using PRIO_xxx constants (use the import tag :prio |
589 | that you can refer to using PRIO_xxx constants (use the import tag :prio |
282 | to get then): |
590 | to get then): |
283 | |
591 | |
284 | PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN |
592 | PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN |
285 | 3 > 1 > 0 > -1 > -3 > -4 |
593 | 3 > 1 > 0 > -1 > -3 > -4 |
286 | |
594 | |
287 | # set priority to HIGH |
595 | # set priority to HIGH |
288 | current->prio(PRIO_HIGH); |
596 | current->prio (PRIO_HIGH); |
289 | |
597 | |
290 | The idle coroutine ($Coro::idle) always has a lower priority than any |
598 | The idle coro ($Coro::idle) always has a lower priority than any |
291 | existing coroutine. |
599 | existing coro. |
292 | |
600 | |
293 | Changing the priority of the current process will take effect immediately, |
601 | Changing the priority of the current coro will take effect immediately, |
294 | but changing the priority of processes in the ready queue (but not |
602 | but changing the priority of coro in the ready queue (but not |
295 | running) will only take effect after the next schedule (of that |
603 | running) will only take effect after the next schedule (of that |
296 | process). This is a bug that will be fixed in some future version. |
604 | coro). This is a bug that will be fixed in some future version. |
297 | |
605 | |
298 | =cut |
|
|
299 | |
|
|
300 | sub prio { |
|
|
301 | my $old = $_[0]{prio}; |
|
|
302 | $_[0]{prio} = $_[1] if @_ > 1; |
|
|
303 | $old; |
|
|
304 | } |
|
|
305 | |
|
|
306 | =item $newprio = $process->nice($change) |
606 | =item $newprio = $coro->nice ($change) |
307 | |
607 | |
308 | Similar to C<prio>, but subtract the given value from the priority (i.e. |
608 | Similar to C<prio>, but subtract the given value from the priority (i.e. |
309 | higher values mean lower priority, just as in unix). |
609 | higher values mean lower priority, just as in unix). |
310 | |
610 | |
311 | =cut |
|
|
312 | |
|
|
313 | sub nice { |
|
|
314 | $_[0]{prio} -= $_[1]; |
|
|
315 | } |
|
|
316 | |
|
|
317 | =item $olddesc = $process->desc($newdesc) |
611 | =item $olddesc = $coro->desc ($newdesc) |
318 | |
612 | |
319 | Sets (or gets in case the argument is missing) the description for this |
613 | Sets (or gets in case the argument is missing) the description for this |
320 | process. This is just a free-form string you can associate with a process. |
614 | coro. This is just a free-form string you can associate with a |
|
|
615 | coro. |
|
|
616 | |
|
|
617 | This method simply sets the C<< $coro->{desc} >> member to the given |
|
|
618 | string. You can modify this member directly if you wish, and in fact, this |
|
|
619 | is often preferred to indicate major processing states that cna then be |
|
|
620 | seen for example in a L<Coro::Debug> session: |
|
|
621 | |
|
|
622 | sub my_long_function { |
|
|
623 | local $Coro::current->{desc} = "now in my_long_function"; |
|
|
624 | ... |
|
|
625 | $Coro::current->{desc} = "my_long_function: phase 1"; |
|
|
626 | ... |
|
|
627 | $Coro::current->{desc} = "my_long_function: phase 2"; |
|
|
628 | ... |
|
|
629 | } |
321 | |
630 | |
322 | =cut |
631 | =cut |
323 | |
632 | |
324 | sub desc { |
633 | sub desc { |
325 | my $old = $_[0]{desc}; |
634 | my $old = $_[0]{desc}; |
326 | $_[0]{desc} = $_[1] if @_ > 1; |
635 | $_[0]{desc} = $_[1] if @_ > 1; |
327 | $old; |
636 | $old; |
328 | } |
637 | } |
329 | |
638 | |
|
|
639 | sub transfer { |
|
|
640 | require Carp; |
|
|
641 | Carp::croak ("You must not call ->transfer on Coro objects. Use Coro::State objects or the ->schedule_to method. Caught"); |
|
|
642 | } |
|
|
643 | |
330 | =back |
644 | =back |
331 | |
645 | |
|
|
646 | =head1 GLOBAL FUNCTIONS |
|
|
647 | |
|
|
648 | =over 4 |
|
|
649 | |
|
|
650 | =item Coro::nready |
|
|
651 | |
|
|
652 | Returns the number of coro that are currently in the ready state, |
|
|
653 | i.e. that can be switched to by calling C<schedule> directory or |
|
|
654 | indirectly. The value C<0> means that the only runnable coro is the |
|
|
655 | currently running one, so C<cede> would have no effect, and C<schedule> |
|
|
656 | would cause a deadlock unless there is an idle handler that wakes up some |
|
|
657 | coro. |
|
|
658 | |
|
|
659 | =item my $guard = Coro::guard { ... } |
|
|
660 | |
|
|
661 | This function still exists, but is deprecated. Please use the |
|
|
662 | C<Guard::guard> function instead. |
|
|
663 | |
|
|
664 | =cut |
|
|
665 | |
|
|
666 | BEGIN { *guard = \&Guard::guard } |
|
|
667 | |
|
|
668 | =item unblock_sub { ... } |
|
|
669 | |
|
|
670 | This utility function takes a BLOCK or code reference and "unblocks" it, |
|
|
671 | returning a new coderef. Unblocking means that calling the new coderef |
|
|
672 | will return immediately without blocking, returning nothing, while the |
|
|
673 | original code ref will be called (with parameters) from within another |
|
|
674 | coro. |
|
|
675 | |
|
|
676 | The reason this function exists is that many event libraries (such as the |
|
|
677 | venerable L<Event|Event> module) are not thread-safe (a weaker form |
|
|
678 | of reentrancy). This means you must not block within event callbacks, |
|
|
679 | otherwise you might suffer from crashes or worse. The only event library |
|
|
680 | currently known that is safe to use without C<unblock_sub> is L<EV>. |
|
|
681 | |
|
|
682 | Coro will try to catch you when you block in the event loop |
|
|
683 | ("FATAL:$Coro::IDLE blocked itself"), but this is just best effort and |
|
|
684 | only works when you do not run your own event loop. |
|
|
685 | |
|
|
686 | This function allows your callbacks to block by executing them in another |
|
|
687 | coro where it is safe to block. One example where blocking is handy |
|
|
688 | is when you use the L<Coro::AIO|Coro::AIO> functions to save results to |
|
|
689 | disk, for example. |
|
|
690 | |
|
|
691 | In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when |
|
|
692 | creating event callbacks that want to block. |
|
|
693 | |
|
|
694 | If your handler does not plan to block (e.g. simply sends a message to |
|
|
695 | another coro, or puts some other coro into the ready queue), there is |
|
|
696 | no reason to use C<unblock_sub>. |
|
|
697 | |
|
|
698 | Note that you also need to use C<unblock_sub> for any other callbacks that |
|
|
699 | are indirectly executed by any C-based event loop. For example, when you |
|
|
700 | use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it |
|
|
701 | provides callbacks that are the result of some event callback, then you |
|
|
702 | must not block either, or use C<unblock_sub>. |
|
|
703 | |
|
|
704 | =cut |
|
|
705 | |
|
|
706 | our @unblock_queue; |
|
|
707 | |
|
|
708 | # we create a special coro because we want to cede, |
|
|
709 | # to reduce pressure on the coro pool (because most callbacks |
|
|
710 | # return immediately and can be reused) and because we cannot cede |
|
|
711 | # inside an event callback. |
|
|
712 | our $unblock_scheduler = new Coro sub { |
|
|
713 | while () { |
|
|
714 | while (my $cb = pop @unblock_queue) { |
|
|
715 | &async_pool (@$cb); |
|
|
716 | |
|
|
717 | # for short-lived callbacks, this reduces pressure on the coro pool |
|
|
718 | # as the chance is very high that the async_poll coro will be back |
|
|
719 | # in the idle state when cede returns |
|
|
720 | cede; |
|
|
721 | } |
|
|
722 | schedule; # sleep well |
|
|
723 | } |
|
|
724 | }; |
|
|
725 | $unblock_scheduler->{desc} = "[unblock_sub scheduler]"; |
|
|
726 | |
|
|
727 | sub unblock_sub(&) { |
|
|
728 | my $cb = shift; |
|
|
729 | |
|
|
730 | sub { |
|
|
731 | unshift @unblock_queue, [$cb, @_]; |
|
|
732 | $unblock_scheduler->ready; |
|
|
733 | } |
|
|
734 | } |
|
|
735 | |
|
|
736 | =item $cb = rouse_cb |
|
|
737 | |
|
|
738 | Create and return a "rouse callback". That's a code reference that, |
|
|
739 | when called, will remember a copy of its arguments and notify the owner |
|
|
740 | coro of the callback. |
|
|
741 | |
|
|
742 | See the next function. |
|
|
743 | |
|
|
744 | =item @args = rouse_wait [$cb] |
|
|
745 | |
|
|
746 | Wait for the specified rouse callback (or the last one that was created in |
|
|
747 | this coro). |
|
|
748 | |
|
|
749 | As soon as the callback is invoked (or when the callback was invoked |
|
|
750 | before C<rouse_wait>), it will return the arguments originally passed to |
|
|
751 | the rouse callback. In scalar context, that means you get the I<last> |
|
|
752 | argument, just as if C<rouse_wait> had a C<return ($a1, $a2, $a3...)> |
|
|
753 | statement at the end. |
|
|
754 | |
|
|
755 | See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example. |
|
|
756 | |
|
|
757 | =back |
|
|
758 | |
332 | =cut |
759 | =cut |
333 | |
760 | |
334 | 1; |
761 | 1; |
335 | |
762 | |
|
|
763 | =head1 HOW TO WAIT FOR A CALLBACK |
|
|
764 | |
|
|
765 | It is very common for a coro to wait for some callback to be |
|
|
766 | called. This occurs naturally when you use coro in an otherwise |
|
|
767 | event-based program, or when you use event-based libraries. |
|
|
768 | |
|
|
769 | These typically register a callback for some event, and call that callback |
|
|
770 | when the event occured. In a coro, however, you typically want to |
|
|
771 | just wait for the event, simplyifying things. |
|
|
772 | |
|
|
773 | For example C<< AnyEvent->child >> registers a callback to be called when |
|
|
774 | a specific child has exited: |
|
|
775 | |
|
|
776 | my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... }); |
|
|
777 | |
|
|
778 | But from within a coro, you often just want to write this: |
|
|
779 | |
|
|
780 | my $status = wait_for_child $pid; |
|
|
781 | |
|
|
782 | Coro offers two functions specifically designed to make this easy, |
|
|
783 | C<Coro::rouse_cb> and C<Coro::rouse_wait>. |
|
|
784 | |
|
|
785 | The first function, C<rouse_cb>, generates and returns a callback that, |
|
|
786 | when invoked, will save its arguments and notify the coro that |
|
|
787 | created the callback. |
|
|
788 | |
|
|
789 | The second function, C<rouse_wait>, waits for the callback to be called |
|
|
790 | (by calling C<schedule> to go to sleep) and returns the arguments |
|
|
791 | originally passed to the callback. |
|
|
792 | |
|
|
793 | Using these functions, it becomes easy to write the C<wait_for_child> |
|
|
794 | function mentioned above: |
|
|
795 | |
|
|
796 | sub wait_for_child($) { |
|
|
797 | my ($pid) = @_; |
|
|
798 | |
|
|
799 | my $watcher = AnyEvent->child (pid => $pid, cb => Coro::rouse_cb); |
|
|
800 | |
|
|
801 | my ($rpid, $rstatus) = Coro::rouse_wait; |
|
|
802 | $rstatus |
|
|
803 | } |
|
|
804 | |
|
|
805 | In the case where C<rouse_cb> and C<rouse_wait> are not flexible enough, |
|
|
806 | you can roll your own, using C<schedule>: |
|
|
807 | |
|
|
808 | sub wait_for_child($) { |
|
|
809 | my ($pid) = @_; |
|
|
810 | |
|
|
811 | # store the current coro in $current, |
|
|
812 | # and provide result variables for the closure passed to ->child |
|
|
813 | my $current = $Coro::current; |
|
|
814 | my ($done, $rstatus); |
|
|
815 | |
|
|
816 | # pass a closure to ->child |
|
|
817 | my $watcher = AnyEvent->child (pid => $pid, cb => sub { |
|
|
818 | $rstatus = $_[1]; # remember rstatus |
|
|
819 | $done = 1; # mark $rstatus as valud |
|
|
820 | }); |
|
|
821 | |
|
|
822 | # wait until the closure has been called |
|
|
823 | schedule while !$done; |
|
|
824 | |
|
|
825 | $rstatus |
|
|
826 | } |
|
|
827 | |
|
|
828 | |
336 | =head1 BUGS/LIMITATIONS |
829 | =head1 BUGS/LIMITATIONS |
337 | |
830 | |
338 | - you must make very sure that no coro is still active on global |
831 | =over 4 |
339 | destruction. very bad things might happen otherwise (usually segfaults). |
|
|
340 | |
832 | |
|
|
833 | =item fork with pthread backend |
|
|
834 | |
|
|
835 | When Coro is compiled using the pthread backend (which isn't recommended |
|
|
836 | but required on many BSDs as their libcs are completely broken), then |
|
|
837 | coro will not survive a fork. There is no known workaround except to |
|
|
838 | fix your libc and use a saner backend. |
|
|
839 | |
|
|
840 | =item perl process emulation ("threads") |
|
|
841 | |
341 | - this module is not thread-safe. You should only ever use this module |
842 | This module is not perl-pseudo-thread-safe. You should only ever use this |
342 | from the same thread (this requirement might be losened in the future |
843 | module from the first thread (this requirement might be removed in the |
343 | to allow per-thread schedulers, but Coro::State does not yet allow |
844 | future to allow per-thread schedulers, but Coro::State does not yet allow |
344 | this). |
845 | this). I recommend disabling thread support and using processes, as having |
|
|
846 | the windows process emulation enabled under unix roughly halves perl |
|
|
847 | performance, even when not used. |
|
|
848 | |
|
|
849 | =item coro switching is not signal safe |
|
|
850 | |
|
|
851 | You must not switch to another coro from within a signal handler (only |
|
|
852 | relevant with %SIG - most event libraries provide safe signals), I<unless> |
|
|
853 | you are sure you are not interrupting a Coro function. |
|
|
854 | |
|
|
855 | That means you I<MUST NOT> call any function that might "block" the |
|
|
856 | current coro - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or |
|
|
857 | anything that calls those. Everything else, including calling C<ready>, |
|
|
858 | works. |
|
|
859 | |
|
|
860 | =back |
|
|
861 | |
|
|
862 | |
|
|
863 | =head1 WINDOWS PROCESS EMULATION |
|
|
864 | |
|
|
865 | A great many people seem to be confused about ithreads (for example, Chip |
|
|
866 | Salzenberg called me unintelligent, incapable, stupid and gullible, |
|
|
867 | while in the same mail making rather confused statements about perl |
|
|
868 | ithreads (for example, that memory or files would be shared), showing his |
|
|
869 | lack of understanding of this area - if it is hard to understand for Chip, |
|
|
870 | it is probably not obvious to everybody). |
|
|
871 | |
|
|
872 | What follows is an ultra-condensed version of my talk about threads in |
|
|
873 | scripting languages given on the perl workshop 2009: |
|
|
874 | |
|
|
875 | The so-called "ithreads" were originally implemented for two reasons: |
|
|
876 | first, to (badly) emulate unix processes on native win32 perls, and |
|
|
877 | secondly, to replace the older, real thread model ("5.005-threads"). |
|
|
878 | |
|
|
879 | It does that by using threads instead of OS processes. The difference |
|
|
880 | between processes and threads is that threads share memory (and other |
|
|
881 | state, such as files) between threads within a single process, while |
|
|
882 | processes do not share anything (at least not semantically). That |
|
|
883 | means that modifications done by one thread are seen by others, while |
|
|
884 | modifications by one process are not seen by other processes. |
|
|
885 | |
|
|
886 | The "ithreads" work exactly like that: when creating a new ithreads |
|
|
887 | process, all state is copied (memory is copied physically, files and code |
|
|
888 | is copied logically). Afterwards, it isolates all modifications. On UNIX, |
|
|
889 | the same behaviour can be achieved by using operating system processes, |
|
|
890 | except that UNIX typically uses hardware built into the system to do this |
|
|
891 | efficiently, while the windows process emulation emulates this hardware in |
|
|
892 | software (rather efficiently, but of course it is still much slower than |
|
|
893 | dedicated hardware). |
|
|
894 | |
|
|
895 | As mentioned before, loading code, modifying code, modifying data |
|
|
896 | structures and so on is only visible in the ithreads process doing the |
|
|
897 | modification, not in other ithread processes within the same OS process. |
|
|
898 | |
|
|
899 | This is why "ithreads" do not implement threads for perl at all, only |
|
|
900 | processes. What makes it so bad is that on non-windows platforms, you can |
|
|
901 | actually take advantage of custom hardware for this purpose (as evidenced |
|
|
902 | by the forks module, which gives you the (i-) threads API, just much |
|
|
903 | faster). |
|
|
904 | |
|
|
905 | Sharing data is in the i-threads model is done by transfering data |
|
|
906 | structures between threads using copying semantics, which is very slow - |
|
|
907 | shared data simply does not exist. Benchmarks using i-threads which are |
|
|
908 | communication-intensive show extremely bad behaviour with i-threads (in |
|
|
909 | fact, so bad that Coro, which cannot take direct advantage of multiple |
|
|
910 | CPUs, is often orders of magnitude faster because it shares data using |
|
|
911 | real threads, refer to my talk for details). |
|
|
912 | |
|
|
913 | As summary, i-threads *use* threads to implement processes, while |
|
|
914 | the compatible forks module *uses* processes to emulate, uhm, |
|
|
915 | processes. I-threads slow down every perl program when enabled, and |
|
|
916 | outside of windows, serve no (or little) practical purpose, but |
|
|
917 | disadvantages every single-threaded Perl program. |
|
|
918 | |
|
|
919 | This is the reason that I try to avoid the name "ithreads", as it is |
|
|
920 | misleading as it implies that it implements some kind of thread model for |
|
|
921 | perl, and prefer the name "windows process emulation", which describes the |
|
|
922 | actual use and behaviour of it much better. |
345 | |
923 | |
346 | =head1 SEE ALSO |
924 | =head1 SEE ALSO |
347 | |
925 | |
|
|
926 | Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>. |
|
|
927 | |
|
|
928 | Debugging: L<Coro::Debug>. |
|
|
929 | |
348 | Support/Utility: L<Coro::Cont>, L<Coro::Specific>, L<Coro::State>, L<Coro::Util>. |
930 | Support/Utility: L<Coro::Specific>, L<Coro::Util>. |
349 | |
931 | |
350 | Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>. |
932 | Locking and IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, |
|
|
933 | L<Coro::SemaphoreSet>, L<Coro::RWLock>. |
351 | |
934 | |
352 | Event/IO: L<Coro::Timer>, L<Coro::Event>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::Select>. |
935 | I/O and Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>. |
353 | |
936 | |
354 | Embedding: L<Coro:MakeMaker> |
937 | Compatibility with other modules: L<Coro::LWP> (but see also L<AnyEvent::HTTP> for |
|
|
938 | a better-working alternative), L<Coro::BDB>, L<Coro::Storable>, |
|
|
939 | L<Coro::Select>. |
|
|
940 | |
|
|
941 | XS API: L<Coro::MakeMaker>. |
|
|
942 | |
|
|
943 | Low level Configuration, Thread Environment, Continuations: L<Coro::State>. |
355 | |
944 | |
356 | =head1 AUTHOR |
945 | =head1 AUTHOR |
357 | |
946 | |
358 | Marc Lehmann <schmorp@schmorp.de> |
947 | Marc Lehmann <schmorp@schmorp.de> |
359 | http://home.schmorp.de/ |
948 | http://home.schmorp.de/ |