org.apache.hadoop.hbase.io.hfile

Class LruCachedBlockQueue

java.lang.Object

org.apache.hadoop.hbase.io.hfile.LruCachedBlockQueue

All Implemented Interfaces:

HeapSize

@InterfaceAudience.Private
public class LruCachedBlockQueue
extends Object
implements HeapSize

A memory-bound queue that will grow until an element brings total size >= maxSize. From then on, only entries that are sorted larger than the smallest current entry will be inserted/replaced.

Use this when you want to find the largest elements (according to their ordering, not their heap size) that consume as close to the specified maxSize as possible. Default behavior is to grow just above rather than just below specified max.

Object used in this queue must implement HeapSize as well as Comparable.

Field Summary

Fields

Modifier and Type	Field and Description
private long	heapSize
private long	maxSize
private org.apache.hbase.thirdparty.com.google.common.collect.MinMaxPriorityQueue<LruCachedBlock>	queue

Constructor Summary

Constructors

Constructor and Description
LruCachedBlockQueue(long maxSize, long blockSize)

Method Summary

Modifier and Type	Method and Description
void	add(LruCachedBlock cb) Attempt to add the specified cached block to this queue.
long	heapSize() Total size of all elements in this queue.
LruCachedBlock	poll() Returns The next element in this queue, or null if the queue is empty.
LruCachedBlock	pollLast() Returns The last element in this queue, or null if the queue is empty.

Methods inherited from class java.lang.Object

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

Field Detail

queue

private org.apache.hbase.thirdparty.com.google.common.collect.MinMaxPriorityQueue<LruCachedBlock> queue

heapSize

private long heapSize

maxSize

private long maxSize

Constructor Detail

LruCachedBlockQueue

public LruCachedBlockQueue(long maxSize,
                           long blockSize)

Parameters:

maxSize - the target size of elements in the queue

blockSize - expected average size of blocks

Method Detail

add

public void add(LruCachedBlock cb)

Attempt to add the specified cached block to this queue.

If the queue is smaller than the max size, or if the specified element is ordered before the smallest element in the queue, the element will be added to the queue. Otherwise, there is no side effect of this call.

Parameters:

cb - block to try to add to the queue

poll

public LruCachedBlock poll()

Returns The next element in this queue, or null if the queue is empty.

pollLast

public LruCachedBlock pollLast()

Returns The last element in this queue, or null if the queue is empty.

heapSize

public long heapSize()

Total size of all elements in this queue.

Specified by:

heapSize in interface HeapSize

Returns:

size of all elements currently in queue, in bytes