ai.grakn.engine.lock

Class ZookeeperLock

java.lang.Object

ai.grakn.engine.lock.ZookeeperLock

All Implemented Interfaces:

Lock

public class ZookeeperLock
extends Object
implements Lock

A fully distributed lock that is globally synchronous. No two engines or tasks will think they hold the same lock.

Author:

alexandraorth

Constructor Summary

Constructors

Constructor and Description
ZookeeperLock(ZookeeperConnection zookeeper, String lockPath)

Method Summary

Modifier and Type	Method and Description
String	getLockPath()
void	lock() Acquires the lock.
void	lockInterruptibly()
Condition	newCondition()
boolean	tryLock() Acquire the lock if it is available within 1 second of calling.
boolean	tryLock(long time, TimeUnit unit) Acquire the lock if it is available within using .
void	unlock()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ZookeeperLock

public ZookeeperLock(ZookeeperConnection zookeeper,
                     String lockPath)

Method Detail

lock

public void lock()

Acquires the lock. If the lock is not available, stalls the current thread until it is available. See InterProcessSemaphoreMutex.acquire() for more information.

Specified by:

lock in interface Lock

Throws:

ai.grakn.exception.GraknBackendException - when there are Zookeeper connection issues.

lockInterruptibly

public void lockInterruptibly()
                       throws InterruptedException

Specified by:

lockInterruptibly in interface Lock

Throws:

InterruptedException

tryLock

public boolean tryLock()

Acquire the lock if it is available within 1 second of calling. Note: Checking if the lock is available and acquiring the lock IS NOT atomic.

Specified by:

tryLock in interface Lock

Returns:

true if the lock was acquired and false otherwise

tryLock

public boolean tryLock(long time,
                       TimeUnit unit)
                throws InterruptedException

Acquire the lock if it is available within using .

Specified by:

tryLock in interface Lock

Parameters:

time - amount of time to wait for the lock to be available

unit - unit of time that qualifies amount of time to wait for lock

Returns:

@return true if the lock was acquired and false otherwise

Throws:

InterruptedException

unlock

public void unlock()

Specified by:

unlock in interface Lock

Throws:

ai.grakn.exception.GraknBackendException - when there are Zookeeper connection issues.

newCondition

public Condition newCondition()

Specified by:

newCondition in interface Lock

getLockPath

public String getLockPath()