SDF::Lock::Selective 0.01

SDF::Lock::Selective can lock/unlock a file or filehandle using 'selective' locking.

SYNOPSIS

Obtain lock on a filename or filepath

use PTools::SDF::Lock::Selective;

$lockObj = new PTools::SDF::Lock::Selective;

($stat,$err) = $lockObj->lock( $fileName );

or $lockObj->lock( $fileName, $maxRetries, $sleepTime, $lockMode, $openMode );

($stat,$err) = $lockObj->status;

($stat,$err) = $lockObj->unlock;

The '$fileName' need not exist prior to calling the 'lock' method, but it will exist if the lock succeeds.

Default for the '$openMode' variable is 0644, or '-rw-r--r--')

Explicit unlock is unnecessary. Simply allow the '$lockObj' variable to fall out of scope (or exit the script, undefine, etc.) to release the lock.

Obtain lock on an open filehandle

use Fcntl;
use PTools::SDF::Lock::Selective;

$lockObj = new PTools::SDF::Lock::Selective;

local(*FH);
sysopen(FH, "/some/file", O_RDWR|O_CREAT, 0644) || die $!;
$fh = *FH;

($stat,$err) = $lockObj->lock( $fh );
or ($stat,$err) = $lockObj->lock( $fh, $maxRetries, $sleepTime, $lockMode );

The 'status' and 'unlock' methods are the same as above, and an '$openMode' parameter is obviously not needed here.
Obtain lock on an instance of an 'SDF::< module >' class

use PTools::SDF::INI; # or PTools::SDF::SDF, or PTools::SDF::TAG

$iniObj = new PTools::SDF::INI( $fileName );

$iniObj->extend( [ "lock","unlock" ], "PTools::SDF::Lock::Selective");

($stat,$err) = $iniObj->lock( $maxRetries, $sleepTime, $lockMode );

The 'status' and 'unlock' methods are the same as above.
Note that the braces ([, ]) used in the above example show the litersl syntax used to pass an array reference into a subroutine. They are not used here to imply optional parameters. Optionally, use:

$arrayRef = [ "lock", "unlock" ];

$iniObj->extend( $arrayRef, "PTools::SDF::Lock::Selective");

Invoke lock method from within an 'SDF::< module >' class
The lock and unlock methods are implemented as extendible methods in an abstract base class. See PTools::SDF::File or EPTools::xtender for discussion and examples of this mechanism.

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Requirements:

· Perl