org.apache.hadoop.hbase.io.hfile.bucket

Class BucketEntry

java.lang.Object

org.apache.hadoop.hbase.io.hfile.bucket.BucketEntry

All Implemented Interfaces:

HBaseReferenceCounted, org.apache.hbase.thirdparty.io.netty.util.ReferenceCounted

@InterfaceAudience.Private
public class BucketEntry
extends Object
implements HBaseReferenceCounted

Item in cache. We expect this to be where most memory goes. Java uses 8 bytes just for object headers; after this, we want to use as little as possible - so we only use 8 bytes, but in order to do so we end up messing around with all this Java casting stuff. Offset stored as 5 bytes that make up the long. Doubt we'll see devices this big for ages. Offsets are divided by 256. So 5 bytes gives us 256TB or so.

Method Summary

Modifier and Type	Method and Description
long	getCachedTime()
int	getLength()
int	getOnDiskSizeWithHeader()
BlockPriority	getPriority()
int	refCnt()
boolean	release() We've three cases to release refCnt now: 1.
BucketEntry	retain()

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.hadoop.hbase.nio.HBaseReferenceCounted

release, retain, touch, touch

Method Detail

getLength

public int getLength()

getPriority

public BlockPriority getPriority()

getCachedTime

public long getCachedTime()

getOnDiskSizeWithHeader

public int getOnDiskSizeWithHeader()

refCnt

public int refCnt()

Specified by:

refCnt in interface org.apache.hbase.thirdparty.io.netty.util.ReferenceCounted

retain

public BucketEntry retain()

Specified by:

retain in interface org.apache.hbase.thirdparty.io.netty.util.ReferenceCounted

release

public boolean release()

We've three cases to release refCnt now:
1. BucketCache#evictBlock, it will release the backingMap's reference by force because we're closing file or clear the bucket cache or some corruption happen. when all rpc references gone, then free the area in bucketAllocator.
2. BucketCache#returnBlock . when rpc shipped, we'll release the block, only when backingMap also release its refCnt (case.1 will do this) and no other rpc reference, then it will free the area in bucketAllocator.
3.evict those block without any rpc reference if cache size exceeded. we'll only free those blocks with zero rpc reference count.

Specified by:

release in interface org.apache.hbase.thirdparty.io.netty.util.ReferenceCounted

Returns:

true to indicate we've decreased to zero and do the de-allocation.