Method and apparatus for refreshing file locks to minimize confl

Details Method and apparatus for refreshing file locks to minimize confl Method and apparatus for refreshing file locks to minimize confl

1995-07-07

1999-04-06

An, Meng-Ai T.

Electrical computers and digital processing systems: memory

Storage accessing and control

Hierarchical memories

395728, 395727, 395722, 711106, 711145, 711152, 711167, G60F 1300

Patent

active

058929541

ABSTRACT:
A system for generating and maintaining lock files to inhibit conflicting requests for data files. A first process that accesses a data file generates a lock file to prohibit other processes from reading and/or writing that data file. Periodically the first process refreshes the lock file so that it shows a new modification time. A second process requesting access to the data file detect the lock file, stores the time of the attempted access, then waits a predetermined wait period and reads the lock file again. This is repeated, each time waiting for the wait period and again reading the lock file, until either (1) a predetermined time-out period passes without the first process refreshing the lock file, whereupon it is presumed that the process is defunct so the second process may access the data file; or (2) more than a maximum allowed access period of time has passed without the second process gaining access, i.e. the first process continues to refresh the lock file for greater than some predefined period. The refresh period is set to a relatively small period, so that if the first process dies the second process gains access to the data files quickly.

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