Browse Prior Art Database

Status Table Nested Simultaneous Locking Schema

IP.com Disclosure Number: IPCOM000103923D
Original Publication Date: 1993-Feb-01
Included in the Prior Art Database: 2005-Mar-18
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Debry, R: AUTHOR [+5]

Abstract

Disclosed is a file locking schema that provides a nested locking capability for disparate processes.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 100% of the total text.

Status Table Nested Simultaneous Locking Schema

Disclosed is a file locking schema that provides a nested locking
capability for disparate processes.

      In a distributed, multiple workstation, client/server based
backup and restore system it is necessary to have multiple
coordinated processes access the same file while locking other
processes from accessing the file.

      The invention disclosed is a locking schema that does not
release the lock on a file until all processes accessing the file
have completed their work.  This implementation utilizes operating
system locking primitives as a basis.

      A control block structure is maintained for each accessed file.
This control block is identified by a unique handle, a lock count and
the file descriptor for the file.  When a file is accessed, the
control block is checked and, if it indicates the file is currently
locked, the lock count field of the control block is checked and if
it indicates the file is currently locked, the lock count field of
the control block is incremented.  A lock on the file is established
using low level, system independent, AIX*/UNIX** locking mechanisms
if the file is not currently locked.  When a process has completed
activity against a file, the lock count maintained in the control
block is decremented.  The lock on the file is only released when the
lock count is zero.

  *  Trademark of IBM Corp.
**  Trademark of UNIX Systems Laboratories, Inc.