org.apache.hadoop.hive.ql.exec.mr

Class ObjectCache

java.lang.Object

org.apache.hadoop.hive.ql.exec.mr.ObjectCache

All Implemented Interfaces:

ObjectCache

public class ObjectCache
extends Object
implements ObjectCache

ObjectCache. No-op implementation on MR we don't have a means to reuse Objects between runs of the same task.

Constructor Summary

Constructors

Constructor and Description
ObjectCache()

Method Summary

Modifier and Type	Method and Description
void	release(String key)
void	remove(String key) Removes the specified key from the object cache.
<T> T	retrieve(String key) Retrieve object from cache.
<T> T	retrieve(String key, Callable<T> fn) Retrieve object from cache.
<T> Future<T>	retrieveAsync(String key, Callable<T> fn) Retrieve object from cache asynchronously.

Methods inherited from class java.lang.Object

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

Constructor Detail

ObjectCache

public ObjectCache()

Method Detail

release

public void release(String key)

Specified by:

release in interface ObjectCache

retrieve

public <T> T retrieve(String key)
               throws HiveException

Description copied from interface: ObjectCache

Retrieve object from cache.

Specified by:

retrieve in interface ObjectCache

Parameters:

key - function to generate the object if it's not there

Returns:

the last cached object with the key, null if none.

Throws:

HiveException

retrieve

public <T> T retrieve(String key,
                      Callable<T> fn)
               throws HiveException

Description copied from interface: ObjectCache

Retrieve object from cache.

Specified by:

retrieve in interface ObjectCache

fn - function to generate the object if it's not there

Returns:

the last cached object with the key, null if none.

Throws:

HiveException

retrieveAsync

public <T> Future<T> retrieveAsync(String key,
                                   Callable<T> fn)
                            throws HiveException

Description copied from interface: ObjectCache

Retrieve object from cache asynchronously.

Specified by:

retrieveAsync in interface ObjectCache

fn - function to generate the object if it's not there

Returns:

the last cached object with the key, null if none.

Throws:

HiveException

remove

public void remove(String key)

Description copied from interface: ObjectCache

Removes the specified key from the object cache.

Specified by:

remove in interface ObjectCache

Parameters:

key - - key to be removed