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- package Thread;
-
- use strict;
- use warnings;
- no warnings 'redefine';
-
- our $VERSION = '3.02';
- $VERSION = eval $VERSION;
-
- BEGIN {
- use Config;
- if (! $Config{useithreads}) {
- die("This Perl not built to support threads\n");
- }
- }
-
- use threads 'yield';
- use threads::shared;
-
- require Exporter;
- our @ISA = qw(Exporter threads);
- our @EXPORT = qw(cond_wait cond_broadcast cond_signal);
- our @EXPORT_OK = qw(async yield);
-
- sub async (&;@) { return Thread->new(shift); }
-
- sub done { return ! shift->is_running(); }
-
- sub eval { die("'eval' not implemented with 'ithreads'\n"); };
- sub flags { die("'flags' not implemented with 'ithreads'\n"); };
-
- 1;
-
- __END__
-
- =head1 NAME
-
- Thread - Manipulate threads in Perl (for old code only)
-
- =head1 DEPRECATED
-
- The C<Thread> module served as the frontend to the old-style thread model,
- called I<5005threads>, that was introduced in release 5.005. That model was
- deprecated, and has been removed in version 5.10.
-
- For old code and interim backwards compatibility, the C<Thread> module has
- been reworked to function as a frontend for the new interpreter threads
- (I<ithreads>) model. However, some previous functionality is not available.
- Further, the data sharing models between the two thread models are completely
- different, and anything to do with data sharing has to be thought differently.
- With I<ithreads>, you must explicitly C<share()> variables between the
- threads.
-
- You are strongly encouraged to migrate any existing threaded code to the new
- model (i.e., use the C<threads> and C<threads::shared> modules) as soon as
- possible.
-
- =head1 HISTORY
-
- In Perl 5.005, the thread model was that all data is implicitly shared, and
- shared access to data has to be explicitly synchronized. This model is called
- I<5005threads>.
-
- In Perl 5.6, a new model was introduced in which all is was thread local and
- shared access to data has to be explicitly declared. This model is called
- I<ithreads>, for "interpreter threads".
-
- In Perl 5.6, the I<ithreads> model was not available as a public API; only as
- an internal API that was available for extension writers, and to implement
- fork() emulation on Win32 platforms.
-
- In Perl 5.8, the I<ithreads> model became available through the C<threads>
- module, and the I<5005threads> model was deprecated.
-
- In Perl 5.10, the I<5005threads> model was removed from the Perl interpreter.
-
- =head1 SYNOPSIS
-
- use Thread qw(:DEFAULT async yield);
-
- my $t = Thread->new(\&start_sub, @start_args);
-
- $result = $t->join;
- $t->detach;
-
- if ($t->done) {
- $t->join;
- }
-
- if($t->equal($another_thread)) {
- # ...
- }
-
- yield();
-
- my $tid = Thread->self->tid;
-
- lock($scalar);
- lock(@array);
- lock(%hash);
-
- my @list = Thread->list;
-
- =head1 DESCRIPTION
-
- The C<Thread> module provides multithreading support for Perl.
-
- =head1 FUNCTIONS
-
- =over 8
-
- =item $thread = Thread->new(\&start_sub)
-
- =item $thread = Thread->new(\&start_sub, LIST)
-
- C<new> starts a new thread of execution in the referenced subroutine. The
- optional list is passed as parameters to the subroutine. Execution
- continues in both the subroutine and the code after the C<new> call.
-
- C<Thread->new> returns a thread object representing the newly created
- thread.
-
- =item lock VARIABLE
-
- C<lock> places a lock on a variable until the lock goes out of scope.
-
- If the variable is locked by another thread, the C<lock> call will
- block until it's available. C<lock> is recursive, so multiple calls
- to C<lock> are safe--the variable will remain locked until the
- outermost lock on the variable goes out of scope.
-
- Locks on variables only affect C<lock> calls--they do I<not> affect normal
- access to a variable. (Locks on subs are different, and covered in a bit.)
- If you really, I<really> want locks to block access, then go ahead and tie
- them to something and manage this yourself. This is done on purpose.
- While managing access to variables is a good thing, Perl doesn't force
- you out of its living room...
-
- If a container object, such as a hash or array, is locked, all the
- elements of that container are not locked. For example, if a thread
- does a C<lock @a>, any other thread doing a C<lock($a[12])> won't
- block.
-
- Finally, C<lock> will traverse up references exactly I<one> level.
- C<lock(\$a)> is equivalent to C<lock($a)>, while C<lock(\\$a)> is not.
-
- =item async BLOCK;
-
- C<async> creates a thread to execute the block immediately following
- it. This block is treated as an anonymous sub, and so must have a
- semi-colon after the closing brace. Like C<Thread->new>, C<async>
- returns a thread object.
-
- =item Thread->self
-
- The C<Thread-E<gt>self> function returns a thread object that represents
- the thread making the C<Thread-E<gt>self> call.
-
- =item Thread->list
-
- Returns a list of all non-joined, non-detached Thread objects.
-
- =item cond_wait VARIABLE
-
- The C<cond_wait> function takes a B<locked> variable as
- a parameter, unlocks the variable, and blocks until another thread
- does a C<cond_signal> or C<cond_broadcast> for that same locked
- variable. The variable that C<cond_wait> blocked on is relocked
- after the C<cond_wait> is satisfied. If there are multiple threads
- C<cond_wait>ing on the same variable, all but one will reblock waiting
- to reaquire the lock on the variable. (So if you're only using
- C<cond_wait> for synchronization, give up the lock as soon as
- possible.)
-
- =item cond_signal VARIABLE
-
- The C<cond_signal> function takes a locked variable as a parameter and
- unblocks one thread that's C<cond_wait>ing on that variable. If more than
- one thread is blocked in a C<cond_wait> on that variable, only one (and
- which one is indeterminate) will be unblocked.
-
- If there are no threads blocked in a C<cond_wait> on the variable,
- the signal is discarded.
-
- =item cond_broadcast VARIABLE
-
- The C<cond_broadcast> function works similarly to C<cond_signal>.
- C<cond_broadcast>, though, will unblock B<all> the threads that are
- blocked in a C<cond_wait> on the locked variable, rather than only
- one.
-
- =item yield
-
- The C<yield> function allows another thread to take control of the
- CPU. The exact results are implementation-dependent.
-
- =back
-
- =head1 METHODS
-
- =over 8
-
- =item join
-
- C<join> waits for a thread to end and returns any values the thread
- exited with. C<join> will block until the thread has ended, though
- it won't block if the thread has already terminated.
-
- If the thread being C<join>ed C<die>d, the error it died with will
- be returned at this time. If you don't want the thread performing
- the C<join> to die as well, you should either wrap the C<join> in
- an C<eval> or use the C<eval> thread method instead of C<join>.
-
- =item detach
-
- C<detach> tells a thread that it is never going to be joined i.e.
- that all traces of its existence can be removed once it stops running.
- Errors in detached threads will not be visible anywhere - if you want
- to catch them, you should use $SIG{__DIE__} or something like that.
-
- =item equal
-
- C<equal> tests whether two thread objects represent the same thread and
- returns true if they do.
-
- =item tid
-
- The C<tid> method returns the tid of a thread. The tid is
- a monotonically increasing integer assigned when a thread is
- created. The main thread of a program will have a tid of zero,
- while subsequent threads will have tids assigned starting with one.
-
- =item done
-
- The C<done> method returns true if the thread you're checking has
- finished, and false otherwise.
-
- =back
-
- =head1 DEFUNCT
-
- The following were implemented with I<5005threads>, but are no longer
- available with I<ithreads>.
-
- =over 8
-
- =item lock(\&sub)
-
- With 5005threads, you could also C<lock> a sub such that any calls to that sub
- from another thread would block until the lock was released.
-
- Also, subroutines could be declared with the C<:locked> attribute which would
- serialize access to the subroutine, but allowed different threads
- non-simultaneous access.
-
- =item eval
-
- The C<eval> method wrapped an C<eval> around a C<join>, and so waited for a
- thread to exit, passing along any values the thread might have returned and
- placing any errors into C<$@>.
-
- =item flags
-
- The C<flags> method returned the flags for the thread - an integer value
- corresponding to the internal flags for the thread.
-
- =back
-
- =head1 SEE ALSO
-
- L<threads>, L<threads::shared>, L<Thread::Queue>, L<Thread::Semaphore>
-
- =cut
-