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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); |
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8 | our @EXPORT = qw(share cond_wait cond_broadcast cond_signal _refcnt _id _thrcnt); |
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9 | our $VERSION = '0.90'; |
10 | |
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11 | use Attribute::Handlers; |
12 | |
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13 | |
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14 | if ($Config{'useithreads'}) { |
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15 | *cond_wait = \&cond_wait_enabled; |
16 | *cond_signal = \&cond_signal_enabled; |
17 | *cond_broadcast = \&cond_broadcast_enabled; |
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18 | require XSLoader; |
19 | XSLoader::load('threads::shared',$VERSION); |
20 | } |
21 | else { |
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22 | *share = \&share_disabled; |
23 | *cond_wait = \&cond_wait_disabled; |
24 | *cond_signal = \&cond_signal_disabled; |
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25 | *cond_broadcast = \&cond_broadcast_disabled; |
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26 | } |
27 | |
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28 | |
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29 | sub cond_wait_disabled { return @_ }; |
30 | sub cond_signal_disabled { return @_}; |
31 | sub cond_broadcast_disabled { return @_}; |
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32 | sub share_disabled { return @_} |
33 | |
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34 | $threads::shared::threads_shared = 1; |
35 | |
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36 | sub _thrcnt { 42 } |
37 | |
38 | sub threads::shared::tie::SPLICE |
39 | { |
40 | die "Splice not implemented for shared arrays"; |
41 | } |
42 | |
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43 | sub UNIVERSAL::shared : ATTR { |
44 | my ($package, $symbol, $referent, $attr, $data, $phase) = @_; |
45 | share($referent); |
46 | } |
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47 | |
48 | __END__ |
49 | |
50 | =head1 NAME |
51 | |
52 | threads::shared - Perl extension for sharing data structures between threads |
53 | |
54 | =head1 SYNOPSIS |
55 | |
56 | use threads::shared; |
57 | |
58 | my($foo, @foo, %foo); |
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59 | share($foo); |
60 | share(@foo); |
61 | share(%hash); |
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62 | my $bar = share([]); |
63 | $hash{bar} = share({}); |
64 | |
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65 | lock(%hash); |
66 | unlock(%hash); |
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67 | cond_wait($scalar); |
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68 | cond_broadcast(@array); |
69 | cond_signal(%hash); |
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70 | |
71 | =head1 DESCRIPTION |
72 | |
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73 | This modules allows you to share() variables. These variables will |
74 | then be shared across different threads (and pseudoforks on |
75 | win32). They are used together with the threads module. |
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76 | |
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77 | =head1 EXPORT |
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78 | |
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79 | C<share>, C<lock>, C<unlock>, C<cond_wait>, C<cond_signal>, C<cond_broadcast> |
80 | |
81 | =head1 FUNCTIONS |
82 | |
83 | =over 4 |
84 | |
85 | =item share VARIABLE |
86 | |
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87 | C<share> takes a value and marks it as shared, you can share a scalar, array, hash |
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88 | scalar ref, array ref and hash ref, C<share> will return the shared value. |
89 | |
90 | C<share> will traverse up references exactly I<one> level. |
91 | C<share(\$a)> is equivalent to C<share($a)>, while C<share(\\$a)> is not. |
92 | |
93 | =item lock VARIABLE |
94 | |
95 | C<lock> places a lock on a variable until the lock goes out of scope. If |
96 | the variable is locked by another thread, the C<lock> call will block until |
97 | it's available. C<lock> is recursive, so multiple calls to C<lock> are |
98 | safe--the variable will remain locked until the outermost lock on the |
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99 | variable goes out of scope or C<unlock> is called enough times to match |
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100 | the number of calls to <lock>. |
101 | |
102 | If a container object, such as a hash or array, is locked, all the elements |
103 | of that container are not locked. For example, if a thread does a C<lock |
104 | @a>, any other thread doing a C<lock($a[12])> won't block. |
105 | |
106 | C<lock> will traverse up references exactly I<one> level. |
107 | C<lock(\$a)> is equivalent to C<lock($a)>, while C<lock(\\$a)> is not. |
108 | |
109 | |
110 | =item unlock VARIABLE |
111 | |
112 | C<unlock> takes a locked shared value and decrements the lock count. |
113 | If the lock count is zero the variable is unlocked. It is not necessary |
114 | to call C<unlock> but it can be usefull to reduce lock contention. |
115 | |
116 | C<unlock> will traverse up references exactly I<one> level. |
117 | C<unlock(\$a)> is equivalent to C<unlock($a)>, while C<unlock(\\$a)> is not. |
118 | |
119 | =item cond_wait VARIABLE |
120 | |
121 | The C<cond_wait> function takes a B<locked> variable as a parameter, |
122 | unlocks the variable, and blocks until another thread does a C<cond_signal> |
123 | or C<cond_broadcast> for that same locked variable. The variable that |
124 | C<cond_wait> blocked on is relocked after the C<cond_wait> is satisfied. |
125 | If there are multiple threads C<cond_wait>ing on the same variable, all but |
126 | one will reblock waiting to reaquire the lock on the variable. (So if |
127 | you're only using C<cond_wait> for synchronization, give up the lock as |
128 | soon as possible) |
129 | |
130 | It is important to note that the variable can be notified even if no |
131 | thread C<cond_signal> or C<cond_broadcast> on the variable. It is therefore |
132 | important to check the value of the variable and go back to waiting if the |
133 | requirment is not fullfilled. |
134 | |
135 | =item cond_signal VARIABLE |
136 | |
137 | The C<cond_signal> function takes a B<locked> variable as a parameter and |
138 | unblocks one thread that's C<cond_wait>ing on that variable. If more than |
139 | one thread is blocked in a C<cond_wait> on that variable, only one (and |
140 | which one is indeterminate) will be unblocked. |
141 | |
142 | If there are no threads blocked in a C<cond_wait> on the variable, the |
143 | signal is discarded. |
144 | |
145 | =item cond_broadcast VARIABLE |
146 | |
147 | The C<cond_broadcast> function works similarly to C<cond_signal>. |
148 | C<cond_broadcast>, though, will unblock B<all> the threads that are blocked |
149 | in a C<cond_wait> on the locked variable, rather than only one. |
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150 | |
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151 | |
152 | =head1 NOTES |
153 | |
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154 | threads::shared is designed to disable itself silently if threads are |
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155 | not available. If you want access to threads, you must C<use threads> |
156 | before you C<use threads::shared>. threads will emit a warning if you |
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157 | use it after threads::shared. |
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158 | |
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159 | =head1 BUGS |
160 | |
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161 | C<bless> is not supported on shared references, in the current version |
162 | C<bless> will only bless the thread local reference and the blessing |
163 | will not propagate to the other threads, this is expected to be implmented |
164 | in the future. |
165 | |
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166 | Does not support splice on arrays! |
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167 | |
168 | =head1 AUTHOR |
169 | |
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170 | Arthur Bergman E<lt>arthur at contiller.seE<gt> |
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171 | |
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172 | threads::shared is released under the same license as Perl |
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173 | |
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174 | Documentation borrowed from Thread.pm |
175 | |
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176 | =head1 SEE ALSO |
177 | |
178 | L<perl> L<threads> |
179 | |
180 | =cut |
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181 | |
182 | |
183 | |
184 | |
185 | |