The lock subsystem provides interprocess and intraprocess concurrency control mechanisms. While the locking system is used extensively by the Berkeley DB access methods and transaction system, it may also be used as a stand-alone subsystem to provide concurrency control to any set of designated resources.
The lock subsystem is created, initialized, and opened by calls to
BDB::Env#open
with the DBD::INIT_LOCK or
DBB::INIT_CDB flags specified.
The following options can be given when the environnement is created
Exception generated by lock call
Lock not held by locker
Lock not granted
Locker killed to resolve a deadlock
A lock ID can be obtained with BDB::Env#lock_id
See also BDB::Env#lock_stat and BDB::Env#lock_detect
get(string, mode , flags = 0)
lock_get(string, mode [, flags])
The lock_get function acquires a lock from the lock table, it return an object BDB::Lock
string specifies the object to be locked or released.
mode is an index into the environment's lock conflict array
flags value must be set to 0 or the value BDBD::LOCK_NOWAIT in this case if a lock cannot be granted because the requested lock conflicts with an existing lock, raise an error BDB::LockGranted
vec(array , flags = 0)
lock_vec(array [, flags])
put()
lock_put()
release()
delete()