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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 | $threads::shared::threads_shared = 1; |
38 | |
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39 | sub _thrcnt { 42 } |
40 | |
41 | sub threads::shared::tie::SPLICE |
42 | { |
43 | die "Splice not implemented for shared arrays"; |
44 | } |
45 | |
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46 | |
47 | __END__ |
48 | |
49 | =head1 NAME |
50 | |
51 | threads::shared - Perl extension for sharing data structures between threads |
52 | |
53 | =head1 SYNOPSIS |
54 | |
55 | use threads::shared; |
56 | |
57 | my($foo, @foo, %foo); |
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58 | share($foo); |
59 | share(@foo); |
60 | share(%hash); |
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61 | my $bar = share([]); |
62 | $hash{bar} = share({}); |
63 | |
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64 | lock(%hash); |
65 | unlock(%hash); |
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66 | cond_wait($scalar); |
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67 | cond_broadcast(@array); |
68 | cond_signal(%hash); |
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69 | |
70 | =head1 DESCRIPTION |
71 | |
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72 | This modules allows you to share() variables. These variables will |
73 | then be shared across different threads (and pseudoforks on |
74 | win32). They are used together with the threads module. |
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75 | |
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76 | =head1 EXPORT |
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77 | |
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78 | C<share>, C<lock>, C<unlock>, C<cond_wait>, C<cond_signal>, C<cond_broadcast> |
79 | |
80 | =head1 FUNCTIONS |
81 | |
82 | =over 4 |
83 | |
84 | =item share VARIABLE |
85 | |
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86 | C<share> takes a value and marks it as shared, you can share a scalar, array, hash |
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87 | scalar ref, array ref and hash ref, C<share> will return the shared value. |
88 | |
89 | C<share> will traverse up references exactly I<one> level. |
90 | C<share(\$a)> is equivalent to C<share($a)>, while C<share(\\$a)> is not. |
91 | |
92 | =item lock VARIABLE |
93 | |
94 | C<lock> places a lock on a variable until the lock goes out of scope. If |
95 | the variable is locked by another thread, the C<lock> call will block until |
96 | it's available. C<lock> is recursive, so multiple calls to C<lock> are |
97 | safe--the variable will remain locked until the outermost lock on the |
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98 | variable goes out of scope or C<unlock> is called enough times to match |
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99 | the number of calls to <lock>. |
100 | |
101 | If a container object, such as a hash or array, is locked, all the elements |
102 | of that container are not locked. For example, if a thread does a C<lock |
103 | @a>, any other thread doing a C<lock($a[12])> won't block. |
104 | |
105 | C<lock> will traverse up references exactly I<one> level. |
106 | C<lock(\$a)> is equivalent to C<lock($a)>, while C<lock(\\$a)> is not. |
107 | |
108 | |
109 | =item unlock VARIABLE |
110 | |
111 | C<unlock> takes a locked shared value and decrements the lock count. |
112 | If the lock count is zero the variable is unlocked. It is not necessary |
113 | to call C<unlock> but it can be usefull to reduce lock contention. |
114 | |
115 | C<unlock> will traverse up references exactly I<one> level. |
116 | C<unlock(\$a)> is equivalent to C<unlock($a)>, while C<unlock(\\$a)> is not. |
117 | |
118 | =item cond_wait VARIABLE |
119 | |
120 | The C<cond_wait> function takes a B<locked> variable as a parameter, |
121 | unlocks the variable, and blocks until another thread does a C<cond_signal> |
122 | or C<cond_broadcast> for that same locked variable. The variable that |
123 | C<cond_wait> blocked on is relocked after the C<cond_wait> is satisfied. |
124 | If there are multiple threads C<cond_wait>ing on the same variable, all but |
125 | one will reblock waiting to reaquire the lock on the variable. (So if |
126 | you're only using C<cond_wait> for synchronization, give up the lock as |
127 | soon as possible) |
128 | |
129 | It is important to note that the variable can be notified even if no |
130 | thread C<cond_signal> or C<cond_broadcast> on the variable. It is therefore |
131 | important to check the value of the variable and go back to waiting if the |
132 | requirment is not fullfilled. |
133 | |
134 | =item cond_signal VARIABLE |
135 | |
136 | The C<cond_signal> function takes a B<locked> variable as a parameter and |
137 | unblocks one thread that's C<cond_wait>ing on that variable. If more than |
138 | one thread is blocked in a C<cond_wait> on that variable, only one (and |
139 | which one is indeterminate) will be unblocked. |
140 | |
141 | If there are no threads blocked in a C<cond_wait> on the variable, the |
142 | signal is discarded. |
143 | |
144 | =item cond_broadcast VARIABLE |
145 | |
146 | The C<cond_broadcast> function works similarly to C<cond_signal>. |
147 | C<cond_broadcast>, though, will unblock B<all> the threads that are blocked |
148 | in a C<cond_wait> on the locked variable, rather than only one. |
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149 | |
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150 | |
151 | =head1 NOTES |
152 | |
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153 | threads::shared is designed to disable itself silently if threads are |
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154 | not available. If you want access to threads, you must C<use threads> |
155 | before you C<use threads::shared>. threads will emit a warning if you |
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156 | use it after threads::shared. |
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157 | |
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158 | =head1 BUGS |
159 | |
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160 | C<bless> is not supported on shared references, in the current version |
161 | C<bless> will only bless the thread local reference and the blessing |
162 | will not propagate to the other threads, this is expected to be implmented |
163 | in the future. |
164 | |
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165 | Does not support splice on arrays! |
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166 | |
167 | =head1 AUTHOR |
168 | |
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169 | Arthur Bergman E<lt>arthur at contiller.seE<gt> |
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170 | |
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171 | threads::shared is released under the same license as Perl |
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172 | |
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173 | Documentation borrowed from Thread.pm |
174 | |
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175 | =head1 SEE ALSO |
176 | |
177 | L<perl> L<threads> |
178 | |
179 | =cut |
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180 | |
181 | |
182 | |
183 | |
184 | |