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1 | package threads::shared; |
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2 | use strict; |
3 | use warnings; |
4 | use Config; |
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5 | |
6 | require Exporter; |
7 | our @ISA = qw(Exporter); |
8 | our @EXPORT = qw(share cond_wait cond_broadcast cond_signal unlock); |
9 | our $VERSION = '0.90'; |
10 | |
11 | use XSLoader; |
12 | XSLoader::load('threads::shared',$VERSION); |
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13 | |
14 | BEGIN { |
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15 | if ($Config{'useithreads'}) { |
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16 | *cond_wait = \&cond_wait_enabled; |
17 | *cond_signal = \&cond_signal_enabled; |
18 | *cond_broadcast = \&cond_broadcast_enabled; |
19 | *unlock = \&unlock_enabled; |
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20 | } else { |
21 | *share = \&share_disabled; |
22 | *cond_wait = \&cond_wait_disabled; |
23 | *cond_signal = \&cond_signal_disabled; |
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24 | *cond_broadcast = \&cond_broadcast_disabled; |
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25 | *unlock = \&unlock_disabled; |
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26 | } |
27 | } |
28 | |
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29 | |
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30 | sub cond_wait_disabled { return @_ }; |
31 | sub cond_signal_disabled { return @_}; |
32 | sub cond_broadcast_disabled { return @_}; |
33 | sub unlock_disabled { 1 }; |
34 | sub lock_disabled { 1 } |
35 | sub share_disabled { return @_} |
36 | |
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37 | $threads::shared::threads_shared = 1; |
38 | |
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39 | |
40 | __END__ |
41 | |
42 | =head1 NAME |
43 | |
44 | threads::shared - Perl extension for sharing data structures between threads |
45 | |
46 | =head1 SYNOPSIS |
47 | |
48 | use threads::shared; |
49 | |
50 | my($foo, @foo, %foo); |
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51 | share($foo); |
52 | share(@foo); |
53 | share(%hash); |
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54 | my $bar = share([]); |
55 | $hash{bar} = share({}); |
56 | |
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57 | lock(%hash); |
58 | unlock(%hash); |
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59 | cond_wait($scalar); |
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60 | cond_broadcast(@array); |
61 | cond_signal(%hash); |
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62 | |
63 | =head1 DESCRIPTION |
64 | |
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65 | This modules allows you to share() variables. These variables will |
66 | then be shared across different threads (and pseudoforks on |
67 | win32). They are used together with the threads module. |
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68 | |
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69 | =head1 EXPORT |
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70 | |
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71 | C<share>, C<lock>, C<unlock>, C<cond_wait>, C<cond_signal>, C<cond_broadcast> |
72 | |
73 | =head1 FUNCTIONS |
74 | |
75 | =over 4 |
76 | |
77 | =item share VARIABLE |
78 | |
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79 | C<share> takes a value and marks it as shared, you can share a scalar, array, hash |
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80 | scalar ref, array ref and hash ref, C<share> will return the shared value. |
81 | |
82 | C<share> will traverse up references exactly I<one> level. |
83 | C<share(\$a)> is equivalent to C<share($a)>, while C<share(\\$a)> is not. |
84 | |
85 | =item lock VARIABLE |
86 | |
87 | C<lock> places a lock on a variable until the lock goes out of scope. If |
88 | the variable is locked by another thread, the C<lock> call will block until |
89 | it's available. C<lock> is recursive, so multiple calls to C<lock> are |
90 | safe--the variable will remain locked until the outermost lock on the |
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91 | variable goes out of scope or C<unlock> is called enough times to match |
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92 | the number of calls to <lock>. |
93 | |
94 | If a container object, such as a hash or array, is locked, all the elements |
95 | of that container are not locked. For example, if a thread does a C<lock |
96 | @a>, any other thread doing a C<lock($a[12])> won't block. |
97 | |
98 | C<lock> will traverse up references exactly I<one> level. |
99 | C<lock(\$a)> is equivalent to C<lock($a)>, while C<lock(\\$a)> is not. |
100 | |
101 | |
102 | =item unlock VARIABLE |
103 | |
104 | C<unlock> takes a locked shared value and decrements the lock count. |
105 | If the lock count is zero the variable is unlocked. It is not necessary |
106 | to call C<unlock> but it can be usefull to reduce lock contention. |
107 | |
108 | C<unlock> will traverse up references exactly I<one> level. |
109 | C<unlock(\$a)> is equivalent to C<unlock($a)>, while C<unlock(\\$a)> is not. |
110 | |
111 | =item cond_wait VARIABLE |
112 | |
113 | The C<cond_wait> function takes a B<locked> variable as a parameter, |
114 | unlocks the variable, and blocks until another thread does a C<cond_signal> |
115 | or C<cond_broadcast> for that same locked variable. The variable that |
116 | C<cond_wait> blocked on is relocked after the C<cond_wait> is satisfied. |
117 | If there are multiple threads C<cond_wait>ing on the same variable, all but |
118 | one will reblock waiting to reaquire the lock on the variable. (So if |
119 | you're only using C<cond_wait> for synchronization, give up the lock as |
120 | soon as possible) |
121 | |
122 | It is important to note that the variable can be notified even if no |
123 | thread C<cond_signal> or C<cond_broadcast> on the variable. It is therefore |
124 | important to check the value of the variable and go back to waiting if the |
125 | requirment is not fullfilled. |
126 | |
127 | =item cond_signal VARIABLE |
128 | |
129 | The C<cond_signal> function takes a B<locked> variable as a parameter and |
130 | unblocks one thread that's C<cond_wait>ing on that variable. If more than |
131 | one thread is blocked in a C<cond_wait> on that variable, only one (and |
132 | which one is indeterminate) will be unblocked. |
133 | |
134 | If there are no threads blocked in a C<cond_wait> on the variable, the |
135 | signal is discarded. |
136 | |
137 | =item cond_broadcast VARIABLE |
138 | |
139 | The C<cond_broadcast> function works similarly to C<cond_signal>. |
140 | C<cond_broadcast>, though, will unblock B<all> the threads that are blocked |
141 | in a C<cond_wait> on the locked variable, rather than only one. |
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142 | |
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143 | |
144 | =head1 NOTES |
145 | |
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146 | threads::shared is designed to disable itself silently if threads are |
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147 | not available. If you want access to threads, you must C<use threads> |
148 | before you C<use threads::shared>. threads will emit a warning if you |
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149 | use it after threads::shared. |
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150 | |
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151 | =head1 BUGS |
152 | |
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153 | C<bless> is not supported on shared references, in the current version |
154 | C<bless> will only bless the thread local reference and the blessing |
155 | will not propagate to the other threads, this is expected to be implmented |
156 | in the future. |
157 | |
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158 | Does not support splice on arrays! |
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159 | |
160 | =head1 AUTHOR |
161 | |
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162 | Arthur Bergman E<lt>arthur at contiller.seE<gt> |
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163 | |
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164 | threads::shared is released under the same license as Perl |
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165 | |
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166 | Documentation borrowed from Thread.pm |
167 | |
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168 | =head1 SEE ALSO |
169 | |
170 | L<perl> L<threads> |
171 | |
172 | =cut |
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173 | |
174 | |
175 | |
176 | |
177 | |