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

Class CachedEntryQueue

java.lang.Object

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

@InterfaceAudience.Private
public class CachedEntryQueue
extends Object

A memory-bound queue that will grow until an element brings total size larger than 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.

Constructor Summary

Constructors

Constructor and Description
CachedEntryQueue(long maxSize, long blockSize)

Method Summary

Modifier and Type	Method and Description
void	add(Map.Entry<BlockCacheKey,org.apache.hadoop.hbase.io.hfile.bucket.BucketCache.BucketEntry> entry) Attempt to add the specified entry to this queue.
long	cacheSize() Total size of all elements in this queue.
Map.Entry<BlockCacheKey,org.apache.hadoop.hbase.io.hfile.bucket.BucketCache.BucketEntry>	poll()
Map.Entry<BlockCacheKey,org.apache.hadoop.hbase.io.hfile.bucket.BucketCache.BucketEntry>	pollLast()

Methods inherited from class java.lang.Object

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

Constructor Detail

CachedEntryQueue

public CachedEntryQueue(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(Map.Entry<BlockCacheKey,org.apache.hadoop.hbase.io.hfile.bucket.BucketCache.BucketEntry> entry)

Attempt to add the specified entry to this queue.

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

Parameters:

entry - a bucket entry with key to try to add to the queue

poll

public Map.Entry<BlockCacheKey,org.apache.hadoop.hbase.io.hfile.bucket.BucketCache.BucketEntry> poll()

Returns:

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

pollLast

public Map.Entry<BlockCacheKey,org.apache.hadoop.hbase.io.hfile.bucket.BucketCache.BucketEntry> pollLast()

Returns:

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

cacheSize

public long cacheSize()

Total size of all elements in this queue.

Returns:

size of all elements currently in queue, in bytes