File Lock Types

Defines
#define	APR_FLOCK_SHARED   1
#define	APR_FLOCK_EXCLUSIVE   2
#define	APR_FLOCK_TYPEMASK   0x000F
#define	APR_FLOCK_NONBLOCK   0x0010

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Define Documentation

#define APR_FLOCK_EXCLUSIVE   2

Exclusive lock. Only one process may hold an exclusive lock at any given time. This is analogous to a "write lock".

#define APR_FLOCK_NONBLOCK   0x0010

do not block while acquiring the file lock

#define APR_FLOCK_SHARED   1

Shared lock. More than one process or thread can hold a shared lock at any given time. Essentially, this is a "read lock", preventing writers from establishing an exclusive lock.

#define APR_FLOCK_TYPEMASK   0x000F

mask to extract lock type