Package org.apache.hadoop.hbase.util

Class IdReadWriteLock<T>

java.lang.Object

org.apache.hadoop.hbase.util.IdReadWriteLock<T>

@Private
public class IdReadWriteLock<T>
extends Object

Allows multiple concurrent clients to lock on a numeric id with ReentrantReadWriteLock. The intended usage for read lock is as follows:

 ReentrantReadWriteLock lock = idReadWriteLock.getLock(id);
 try {
   lock.readLock().lock();
   // User code.
 } finally {
   lock.readLock().unlock();
 }
 

For write lock, use lock.writeLock()

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static enum	IdReadWriteLock.ReferenceType

Field Summary

Fields

Modifier and Type	Field	Description
private final ObjectPool<T,ReentrantReadWriteLock>	lockPool	The pool to get entry from, entries are mapped by Reference and will be automatically garbage-collected by JVM
private static final int	NB_CONCURRENT_LOCKS
private final IdReadWriteLock.ReferenceType	refType

Constructor Summary

Constructors

Constructor	Description
IdReadWriteLock()
IdReadWriteLock(IdReadWriteLock.ReferenceType referenceType)	Constructor of IdReadWriteLock

Method Summary

Modifier and Type	Method	Description
private void	gc()
ReentrantReadWriteLock	getLock(T id)	Get the ReentrantReadWriteLock corresponding to the given id
IdReadWriteLock.ReferenceType	getReferenceType()
(package private) int	purgeAndGetEntryPoolSize()	For testing
void	waitForWaiters(T id, int numWaiters)

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 ObjectPool<T,ReentrantReadWriteLock> lockPool

The pool to get entry from, entries are mapped by Reference and will be automatically garbage-collected by JVM

refType

private final IdReadWriteLock.ReferenceType refType

Constructor Details

IdReadWriteLock

public IdReadWriteLock()

IdReadWriteLock

public IdReadWriteLock(IdReadWriteLock.ReferenceType referenceType)

Constructor of IdReadWriteLock

Parameters:

referenceType - type of the reference used in lock pool, IdReadWriteLock.ReferenceType.WEAK by default. Use IdReadWriteLock.ReferenceType.SOFT if the key set is limited and the locks will be reused with a high frequency

Method Details

getLock

public ReentrantReadWriteLock getLock(T id)

Get the ReentrantReadWriteLock corresponding to the given id

Parameters:

id - an arbitrary number to identify the lock

purgeAndGetEntryPoolSize

int purgeAndGetEntryPoolSize()

For testing

gc

private void gc()

waitForWaiters

public void waitForWaiters(T id,
 int numWaiters)
                    throws InterruptedException

Throws:

InterruptedException

getReferenceType

public IdReadWriteLock.ReferenceType getReferenceType()