Package org.apache.hadoop.hbase.util

Class KeyLocker<K>

java.lang.Object

org.apache.hadoop.hbase.util.KeyLocker<K>

@Private
public class KeyLocker<K>
extends Object

A utility class to manage a set of locks. Each lock is identified by a String which serves as a key. Typical usage is:

 class Example {
   private final static KeyLocker<String> locker = new Locker<String>();

   public void foo(String s) {
     Lock lock = locker.acquireLock(s);
     try {
       // whatever
     } finally {
       lock.unlock();
     }
   }
 }
 

Field Summary

Fields

Modifier and Type	Field	Description
private final WeakObjectPool<K,ReentrantLock>	lockPool
private static final int	NB_CONCURRENT_LOCKS

Constructor Summary

Constructors

Constructor	Description
KeyLocker()

Method Summary

Modifier and Type	Method	Description
ReentrantLock	acquireLock(K key)	Return a lock for the given key.
Map<K,Lock>	acquireLocks(Set<? extends K> keys)	Acquire locks for a set of keys.

Methods inherited from class java.lang.Object

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

Field Details

NB_CONCURRENT_LOCKS

private static final int NB_CONCURRENT_LOCKS

See Also:

• Constant Field Values

lockPool

private final WeakObjectPool<K,ReentrantLock> lockPool

Constructor Details

KeyLocker

public KeyLocker()

Method Details

acquireLock

public ReentrantLock acquireLock(K key)

Return a lock for the given key. The lock is already locked.

acquireLocks

public Map<K,Lock> acquireLocks(Set<? extends K> keys)

Acquire locks for a set of keys. The keys will be sorted internally to avoid possible deadlock.

Throws:

ClassCastException - if the given keys contains elements that are not mutually comparable