Shared Lock

Description

Fully distributed locks that are globally synchronous, meaning at any snapshot in time no two clients think they hold the same lock. Note: unlike InterProcessMutex this lock is not reentrant.

Participating Classes

  • InterProcessSemaphoreMutex

Usage

Create an InterProcessSemaphoreMutex

public InterProcessSemaphoreMutex(CuratorFramework client,
                         String path)
Parameters:
client - client
path - the path to lock

General Usage

To acquire the lock, use one of the acquire methods:

public void acquire()
Acquire the mutex - blocking until it's available. Must be balanced by a call to release().
public boolean acquire(long time,
                       TimeUnit unit)
Acquire the mutex - blocks until it's available or the given time expires. Must be balanced by a call to release().
     
Parameters:
time - time to wait
unit - time unit
Returns:
true if the mutex was acquired, false if not

To release the mutex, call:

public void release()
Perform one release of the mutex if the calling thread is the same thread that acquired it.

Error Handling

It is strongly recommended that you add a ConnectionStateListener and watch for SUSPENDED and LOST state changes. If a SUSPENDED state is reported you cannot be certain that you still hold the lock unless you subsequently receive a RECONNECTED state. If a LOST state is reported it is certain that you no longer hold the lock.