BucketAllocator (Apache HBase 1.2.12 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`
`(package private) class`	`BucketAllocator.BucketSizeInfo`
`(package private) static class`	`BucketAllocator.IndexStatistics`

Field Summary

Fields
Modifier and Type	Field and Description
`private int`	`bigItemSize`
`private long`	`bucketCapacity`
`private BucketAllocator.Bucket[]`	`buckets`
`private BucketAllocator.BucketSizeInfo[]`	`bucketSizeInfos`
`private int[]`	`bucketSizes`
`private static int[]`	`DEFAULT_BUCKET_SIZES`
`static int`	`FEWEST_ITEMS_IN_BUCKET`
`private static org.apache.commons.logging.Log`	`LOG`
`private long`	`totalSize`
`private long`	`usedSize`

Constructor Summary

Constructors
Constructor and Description
`BucketAllocator(long availableSpace, int[] bucketSizes)`
`BucketAllocator(long availableSpace, int[] bucketSizes, Map<BlockCacheKey,BucketCache.BucketEntry> map, AtomicLong realCacheSize)` Rebuild the allocator's data structures from a persisted map.

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()`
`(package private) BucketAllocator.IndexStatistics[]`	`getIndexStatistics()`
`(package private) BucketAllocator.IndexStatistics[]`	`getIndexStatistics(BucketAllocator.IndexStatistics grandTotal)`
`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()`
`private BucketAllocator.Bucket`	`grabGlobalCompletelyFreeBucket()`
`(package private) void`	`logStatistics()`
`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

LOG

private static final org.apache.commons.logging.Log LOG

DEFAULT_BUCKET_SIZES

private static final int[] DEFAULT_BUCKET_SIZES

FEWEST_ITEMS_IN_BUCKET
```
public static final int FEWEST_ITEMS_IN_BUCKET
```
See Also:
Constant Field Values

bucketSizes
```
private final int[] bucketSizes
```

bigItemSize
```
private final int bigItemSize
```

bucketCapacity
```
private final long bucketCapacity
```

buckets

private BucketAllocator.Bucket[] buckets

bucketSizeInfos

private BucketAllocator.BucketSizeInfo[] bucketSizeInfos

totalSize
```
private final long totalSize
```

usedSize
```
private long usedSize
```

Constructor Detail

BucketAllocator

BucketAllocator(long availableSpace,
               int[] bucketSizes)
          throws BucketAllocatorException

Throws:: BucketAllocatorException

BucketAllocator
```
BucketAllocator(long availableSpace,
               int[] bucketSizes,
               Map<BlockCacheKey,BucketCache.BucketEntry> map,
               AtomicLong realCacheSize)
          throws BucketAllocatorException
```
Rebuild the allocator's data structures from a persisted map.

Parameters:
availableSpace - capacity of cache
map - A map stores the block key and BucketEntry(block's meta data like offset, length)
realCacheSize - cached data size statistics for bucket cache

Throws:

BucketAllocatorException

Method Detail
- roundUpToBucketSizeInfo
```
public 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
- grabGlobalCompletelyFreeBucket
```
private BucketAllocator.Bucket grabGlobalCompletelyFreeBucket()
```
- 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()
```
- logStatistics
```
void logStatistics()
```
- getIndexStatistics
```
BucketAllocator.IndexStatistics[] getIndexStatistics(BucketAllocator.IndexStatistics grandTotal)
```
- getIndexStatistics
```
BucketAllocator.IndexStatistics[] getIndexStatistics()
```
- 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

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

LOG

DEFAULT_BUCKET_SIZES

FEWEST_ITEMS_IN_BUCKET

bucketSizes

bigItemSize

bucketCapacity

buckets

bucketSizeInfos

totalSize

usedSize

Constructor Detail

BucketAllocator

BucketAllocator

Method Detail

roundUpToBucketSizeInfo

toString

getUsedSize

getFreeSize

getTotalSize

allocateBlock

grabGlobalCompletelyFreeBucket

freeBlock

sizeIndexOfAllocation

sizeOfAllocation

getBuckets

logStatistics

getIndexStatistics

getIndexStatistics

freeBlock

getBucketIndex

getLeastFilledBuckets