Apache Portable Runtime
|#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