1 package threads::shared;
7 our @ISA = qw(Exporter);
8 our @EXPORT = qw(share cond_wait cond_broadcast cond_signal _refcnt _id _thrcnt);
11 use Attribute::Handlers;
14 if ($Config{'useithreads'}) {
15 *cond_wait = \&cond_wait_enabled;
16 *cond_signal = \&cond_signal_enabled;
17 *cond_broadcast = \&cond_broadcast_enabled;
19 XSLoader::load('threads::shared',$VERSION);
22 *share = \&share_disabled;
23 *cond_wait = \&cond_wait_disabled;
24 *cond_signal = \&cond_signal_disabled;
25 *cond_broadcast = \&cond_broadcast_disabled;
29 sub cond_wait_disabled { return @_ };
30 sub cond_signal_disabled { return @_};
31 sub cond_broadcast_disabled { return @_};
32 sub share_disabled { return @_}
34 $threads::shared::threads_shared = 1;
38 sub threads::shared::tie::SPLICE
40 die "Splice not implemented for shared arrays";
43 sub UNIVERSAL::shared : ATTR {
44 my ($package, $symbol, $referent, $attr, $data, $phase) = @_;
52 threads::shared - Perl extension for sharing data structures between threads
63 $hash{bar} = share({});
68 cond_broadcast(@array);
73 This modules allows you to share() variables. These variables will
74 then be shared across different threads (and pseudoforks on
75 win32). They are used together with the threads module.
79 C<share>, C<lock>, C<unlock>, C<cond_wait>, C<cond_signal>, C<cond_broadcast>
87 C<share> takes a value and marks it as shared, you can share a scalar, array, hash
88 scalar ref, array ref and hash ref, C<share> will return the shared value.
90 C<share> will traverse up references exactly I<one> level.
91 C<share(\$a)> is equivalent to C<share($a)>, while C<share(\\$a)> is not.
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
99 variable goes out of scope or C<unlock> is called enough times to match
100 the number of calls to <lock>.
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($a[12])> won't block.
106 C<lock> will traverse up references exactly I<one> level.
107 C<lock(\$a)> is equivalent to C<lock($a)>, while C<lock(\\$a)> is not.
110 =item unlock VARIABLE
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.
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.
119 =item cond_wait VARIABLE
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
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.
135 =item cond_signal VARIABLE
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.
142 If there are no threads blocked in a C<cond_wait> on the variable, the
145 =item cond_broadcast VARIABLE
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.
154 threads::shared is designed to disable itself silently if threads are
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
157 use it after threads::shared.
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
166 Does not support splice on arrays!
170 Arthur Bergman E<lt>arthur at contiller.seE<gt>
172 threads::shared is released under the same license as Perl
174 Documentation borrowed from Thread.pm