NAME

       MCE::Mutex - Locking for Many-Core Engine

VERSION

       This document describes MCE::Mutex version 1.884

SYNOPSIS

        use MCE::Mutex;

        my $mutex = MCE::Mutex->new;

        {
            use MCE::Flow max_workers => 4;

            mce_flow sub {
                $mutex->lock;

                # access shared resource
                my $wid = MCE->wid; MCE->say($wid); sleep 1;

                $mutex->unlock;
            };
        }

        {
            use MCE::Hobo;

            MCE::Hobo->create('work', $_) for 1..4;
            MCE::Hobo->waitall;
        }

        {
            use threads;

            threads->create('work', $_)   for 5..8;
            $_->join for ( threads->list );
        }

        sub work {
            my ($id) = @_;
            $mutex->lock;

            # access shared resource
            print $id, "\n";
            sleep 1;

            $mutex->unlock;
        }

DESCRIPTION

       This module implements locking methods that can be used to coordinate access to shared
       data from multiple workers spawned as processes or threads.

       The inspiration for this module came from reading Mutex for Ruby.

API DOCUMENTATION

   MCE::Mutex->new ( )
   MCE::Mutex->new ( impl => "Channel" )
   MCE::Mutex->new ( impl => "Flock", [ path => "/tmp/file.lock" ] )
   MCE::Mutex->new ( path => "/tmp/file.lock" )
       Creates a new mutex.

       Channel locking (the default), unless "path" is given, is through a pipe or socket
       depending on the platform. The advantage of channel locking is not having to re-establish
       handles inside new processes and threads.

       For Fcntl-based locking, it is the responsibility of the caller to remove the "tempfile",
       associated with the mutex, when path is given. Otherwise, it establishes a "tempfile"
       internally including removal on scope exit.

   $mutex->impl ( void )
       Returns the implementation used for the mutex.

        $m1 = MCE::Mutex->new( );
        $m1->impl();   # Channel

        $m2 = MCE::Mutex->new( path => /tmp/my.lock );
        $m2->impl();   # Flock

        $m3 = MCE::Mutex->new( impl => "Channel" );
        $m3->impl();   # Channel

        $m4 = MCE::Mutex->new( impl => "Flock" );
        $m4->impl();   # Flock

       Current API available since 1.822.

   $mutex->lock ( void )
   $mutex->lock_exclusive ( void )
       Attempts to grab an exclusive lock and waits if not available. Multiple calls to
       mutex->lock by the same process or thread is safe. The mutex will remain locked until
       mutex->unlock is called.

       The method "lock_exclusive" is an alias for "lock", available since 1.822.

        ( my $mutex = MCE::Mutex->new( path => $0 ) )->lock_exclusive;

   $mutex->lock_shared ( void )
       Like "lock_exclusive", but attempts to grab a shared lock instead.  The "lock_shared"
       method is an alias to "lock" otherwise for non-Fcntl implementations.

       Current API available since 1.822.

   $mutex->unlock ( void )
       Releases the lock. A held lock by an exiting process or thread is released automatically.

   $mutex->synchronize ( sub { ... }, @_ )
   $mutex->enter ( sub { ... }, @_ )
       Obtains a lock, runs the code block, and releases the lock after the block completes.
       Optionally, the method is "wantarray" aware.

        my $val = $mutex->synchronize( sub {
            # access shared resource
            return 'scalar';
        });

        my @ret = $mutex->enter( sub {
            # access shared resource
            return @list;
        });

       The method "enter" is an alias for "synchronize", available since 1.822.

   $mutex->timedwait ( floating_seconds )
       Blocks until obtaining an exclusive lock. A false value is returned if the timeout is
       reached, and a true value otherwise. The default is 1 second.

        my $mutex = MCE::Mutex->new( path => $0 );

        # terminate script if a previous instance is still running

        exit unless $mutex->timedwait( 2 );

        ...

       Current API available since 1.822.

INDEX

       MCE, MCE::Core

AUTHOR

       Mario E. Roy, <marioeroy AT gmail DOT com>