alluxio.master.file.meta

Class LazyUfsBlockLocationCache

java.lang.Object

alluxio.master.file.meta.LazyUfsBlockLocationCache

All Implemented Interfaces:

UfsBlockLocationCache

@ThreadSafe
public class LazyUfsBlockLocationCache
extends Object
implements UfsBlockLocationCache

Lazily cache the block locations only when needed.

Nested Class Summary

Nested classes/interfaces inherited from interface alluxio.master.file.meta.UfsBlockLocationCache

UfsBlockLocationCache.Factory

Constructor Summary

Constructors

Constructor and Description
LazyUfsBlockLocationCache(MountTable mountTable) Creates a new instance of UfsBlockLocationCache.

Method Summary

Modifier and Type	Method and Description
List<String>	get(long blockId)
List<String>	get(long blockId, AlluxioURI fileUri, long offset) If the locations exist in the cache, return them, otherwise, retrieves the block locations from UFS, and caches the result.
void	invalidate(long blockId) Invalidates the UFS locations for the block.

Methods inherited from class java.lang.Object

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

Constructor Detail

LazyUfsBlockLocationCache

public LazyUfsBlockLocationCache(MountTable mountTable)

Creates a new instance of UfsBlockLocationCache.

Parameters:

mountTable - the mount table

Method Detail

invalidate

public void invalidate(long blockId)

Description copied from interface: UfsBlockLocationCache

Invalidates the UFS locations for the block.

Specified by:

invalidate in interface UfsBlockLocationCache

Parameters:

blockId - the block ID

get

public List<String> get(long blockId)

Specified by:

get in interface UfsBlockLocationCache

Parameters:

blockId - the block ID

Returns:

the cached block locations or null if there is no cached locations for the block

get

@Nullable
public List<String> get(long blockId,
                                  AlluxioURI fileUri,
                                  long offset)

Description copied from interface: UfsBlockLocationCache

If the locations exist in the cache, return them, otherwise, retrieves the block locations from UFS, and caches the result. If failed to get the locations from UFS, null is returned and nothing is cached.

Specified by:

get in interface UfsBlockLocationCache

Parameters:

blockId - the block ID

fileUri - the URI of the file which contains the block

offset - the block's offset in the file

Returns:

the block locations or null if it fails to get the locations from UFS