BucketAllocator (Apache HBase 1.4.11 API)

java.lang.Object
- org.apache.hadoop.hbase.io.hfile.bucket.BucketAllocator

```
@InterfaceAudience.Private
public final class BucketAllocator
extends Object
```
This class is used to allocate a block with specified size and free the block when evicting. It manages an array of buckets, each bucket is associated with a size and caches elements up to this size. For a completely empty bucket, this size could be re-specified dynamically. This class is not thread safe.

Nested Class Summary

Nested Classes
Modifier and Type Class and Description

static class BucketAllocator.Bucket

Nested Classes
Modifier and Type	Class and Description
`static class`	`BucketAllocator.Bucket`

Field Summary

Fields
Modifier and Type Field and Description

static int FEWEST_ITEMS_IN_BUCKET
So, what is the minimum amount of items we'll tolerate in a single bucket?

Fields
Modifier and Type	Field and Description
`static int`	`FEWEST_ITEMS_IN_BUCKET` So, what is the minimum amount of items we'll tolerate in a single bucket?

Method Summary

Methods
Modifier and Type	Method and Description
`long`	`allocateBlock(int blockSize)` Allocate a block with specified size.
`int`	`freeBlock(long offset)` Free a block with the offset
`long`	`freeBlock(long[] freeList)`
`int`	`getBucketIndex(long offset)`
`BucketAllocator.Bucket[]`	`getBuckets()`
`long`	`getFreeSize()`
`Set<Integer>`	`getLeastFilledBuckets(Set<Integer> excludedBuckets, int bucketCount)` Returns a set of indices of the buckets that are least filled excluding the offsets, we also the fully free buckets for the BucketSizes where everything is empty and they only have one completely free bucket as a reserved
`long`	`getTotalSize()`
`long`	`getUsedSize()`
`org.apache.hadoop.hbase.io.hfile.bucket.BucketAllocator.BucketSizeInfo`	`roundUpToBucketSizeInfo(int blockSize)` Round up the given block size to bucket size, and get the corresponding BucketSizeInfo
`int`	`sizeIndexOfAllocation(long offset)`
`int`	`sizeOfAllocation(long offset)`
`String`	`toString()`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Field Detail
  - FEWEST_ITEMS_IN_BUCKET
```
public static final int FEWEST_ITEMS_IN_BUCKET
```
    So, what is the minimum amount of items we'll tolerate in a single bucket?
    
    See Also:
    Constant Field Values
- Method Detail
  - roundUpToBucketSizeInfo
```
public org.apache.hadoop.hbase.io.hfile.bucket.BucketAllocator.BucketSizeInfo roundUpToBucketSizeInfo(int blockSize)
```
    Round up the given block size to bucket size, and get the corresponding BucketSizeInfo
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object
  - getUsedSize
```
public long getUsedSize()
```
  - getFreeSize
```
public long getFreeSize()
```
  - getTotalSize
```
public long getTotalSize()
```
  - allocateBlock
```
public long allocateBlock(int blockSize)
                   throws CacheFullException,
                          BucketAllocatorException
```
    Allocate a block with specified size. Return the offset
    
    Parameters:
    blockSize - size of block
    
    Returns:
    the offset in the IOEngine
    
    Throws:
    
    BucketAllocatorException
    
    CacheFullException
  - freeBlock
```
public int freeBlock(long offset)
```
    Free a block with the offset
    
    Parameters:
    offset - block's offset
    
    Returns:
    size freed
  - sizeIndexOfAllocation
```
public int sizeIndexOfAllocation(long offset)
```
  - sizeOfAllocation
```
public int sizeOfAllocation(long offset)
```
  - getBuckets
```
public BucketAllocator.Bucket[] getBuckets()
```
  - freeBlock
```
public long freeBlock(long[] freeList)
```
  - getBucketIndex
```
public int getBucketIndex(long offset)
```
  - getLeastFilledBuckets
```
public Set<Integer> getLeastFilledBuckets(Set<Integer> excludedBuckets,
                                 int bucketCount)
```
    Returns a set of indices of the buckets that are least filled excluding the offsets, we also the fully free buckets for the BucketSizes where everything is empty and they only have one completely free bucket as a reserved
    
    Parameters:
    excludedBuckets - the buckets that need to be excluded due to currently being in used
    bucketCount - max Number of buckets to return
    
    Returns:
    set of bucket indices which could be used for eviction

Class BucketAllocator

Nested Class Summary

Field Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

FEWEST_ITEMS_IN_BUCKET

Method Detail

roundUpToBucketSizeInfo

toString

getUsedSize

getFreeSize

getTotalSize

allocateBlock

freeBlock

sizeIndexOfAllocation

sizeOfAllocation

getBuckets

freeBlock

getBucketIndex

getLeastFilledBuckets