dilock, dilockw, diunlock - lock/unlock RMSfile for inserting
records
#include
int dilock (fcb)
DFILE *fcb;
int dilockw (fcb)
DFILE *fcb;
int diunlock (fcb)
DFILE *fcb;
Dilock attempts to lock an RMSfile exclusively for inserting a
record and returns immediately with a status code. If the RMSfile
can be locked for record insertion, dilock returns a positive
value. If the RMSfile could not be locked for record insertion,
perhaps because it was already locked for insertion by another
process, then a zero value is returned. Locking an RMSfile for
record insertions does not interfere with locking any existing
records for update.
Dilockw attempts to lock an RMSfile exclusively for inserting a
record and waits until the RMSfile can be locked for insertion
before returning. Dilockw normally returns a positive value.
Diunlock unlocks an RMSfile that was locked for insertions using
dilock or dilockw.
Fcb is the file block pointer returned by dlopen(C-3)
or
dopen(C-3).
These routines must be used in a multi-user environment when
calling RMS file functions that insert data records to prevent
simultaneous access to data by more than one process. The RMS
file functions do not automatically lock files or records to
prevent simultaneous insertion of records.
These routines lock the RMSfile so that only one record may be
inserted at a time. This prevents two records being inserted
simultaneously from occupying the same slot. Locking an RMSfile
for record insertions does not interfere with locking existing
records for update.
dflock(C-3), drlock(C-3),
dclock(C-3), dlopen(C-3),
dopen(C-3)
Chapter 4, RMS Programming Guide
Dilock and Dilockw return a value of zero (0) if fcb is not an
opened file block pointer or if locking the RMSfile for insertion
would cause a deadlock.