Package org.apache.hadoop.hbase.util

Class ByteBufferArray

java.lang.Object

org.apache.hadoop.hbase.util.ByteBufferArray

@Private
public class ByteBufferArray
extends Object

This class manages an array of ByteBuffers with a default size 4MB. These buffers are sequential and could be considered as a large buffer.It supports reading/writing data from this large buffer with a position and offset

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private class	ByteBufferArray.BufferIterator	Iterator to fetch ByteBuffers from offset with given length in this big logical array.

Field Summary

Fields

Modifier and Type	Field	Description
private final int	bufferCount
(package private) final ByteBuffer[]	buffers
private final int	bufferSize
static final int	DEFAULT_BUFFER_SIZE
private static final org.slf4j.Logger	LOG
private static final BiConsumer<ByteBuffer,ByteBuff>	READER	Transfer bytes from source ByteBuffer to destination ByteBuff, Position of both source and destination will be advanced.
private static final BiConsumer<ByteBuffer,ByteBuff>	WRITER	Transfer bytes from source ByteBuff to destination ByteBuffer.

Constructor Summary

Constructors

Constructor	Description
ByteBufferArray(int bufferSize, int bufferCount, int threadCount, long capacity, ByteBufferAllocator alloc)
ByteBufferArray(long capacity, ByteBufferAllocator allocator)	We allocate a number of byte buffers as the capacity.

Method Summary

Modifier and Type	Method	Description
ByteBuffer[]	asSubByteBuffers(long offset, int len)	Creates a sub-array from a given array of ByteBuffers from the given offset to the length specified.
private void	createBuffers(int threadCount, ByteBufferAllocator alloc)
private static int	getBufferCount(long capacity)
(package private) static int	getBufferSize(long capacity)
private int	internalTransfer(long offset, ByteBuff b, BiConsumer<ByteBuffer,ByteBuff> transfer)	Transferring all remaining bytes from b to the buffers array starting at offset, or transferring bytes from the buffers array at offset to b until b is filled.
int	read(long offset, ByteBuff dst)	Transfers bytes from this buffers array into the given destination ByteBuff
private static long	roundUp(long n, long to)
int	write(long offset, ByteBuff src)	Transfers bytes from the given source ByteBuff into this buffer array

Methods inherited from class java.lang.Object

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

Field Details

LOG

private static final org.slf4j.Logger LOG

DEFAULT_BUFFER_SIZE

public static final int DEFAULT_BUFFER_SIZE

See Also:

• Constant Field Values

bufferSize

private final int bufferSize

bufferCount

private final int bufferCount

buffers

final ByteBuffer[] buffers

WRITER

private static final BiConsumer<ByteBuffer,ByteBuff> WRITER

Transfer bytes from source ByteBuff to destination ByteBuffer. Position of both source and destination will be advanced.

READER

private static final BiConsumer<ByteBuffer,ByteBuff> READER

Transfer bytes from source ByteBuffer to destination ByteBuff, Position of both source and destination will be advanced.

Constructor Details

ByteBufferArray

public ByteBufferArray(long capacity,
 ByteBufferAllocator allocator)
                throws IOException

We allocate a number of byte buffers as the capacity.

Parameters:

capacity - total size of the byte buffer array

allocator - the ByteBufferAllocator that will create the buffers

Throws:

IOException - throws IOException if there is an exception thrown by the allocator

ByteBufferArray

ByteBufferArray(int bufferSize,
 int bufferCount,
 int threadCount,
 long capacity,
 ByteBufferAllocator alloc)
         throws IOException

Throws:

IOException

Method Details

createBuffers

private void createBuffers(int threadCount,
 ByteBufferAllocator alloc)
                    throws IOException

Throws:

IOException

getBufferSize

static int getBufferSize(long capacity)

getBufferCount

private static int getBufferCount(long capacity)

roundUp

private static long roundUp(long n,
 long to)

read

public int read(long offset,
 ByteBuff dst)

Transfers bytes from this buffers array into the given destination ByteBuff

Parameters:

offset - start position in this big logical array.

dst - the destination ByteBuff. Notice that its position will be advanced.

Returns:

number of bytes read

write

public int write(long offset,
 ByteBuff src)

Transfers bytes from the given source ByteBuff into this buffer array

Parameters:

offset - start offset of this big logical array.

src - the source ByteBuff. Notice that its position will be advanced.

Returns:

number of bytes write

internalTransfer

private int internalTransfer(long offset,
 ByteBuff b,
 BiConsumer<ByteBuffer,ByteBuff> transfer)

Transferring all remaining bytes from b to the buffers array starting at offset, or transferring bytes from the buffers array at offset to b until b is filled. Notice that position of ByteBuff b will be advanced.

Parameters:

offset - where we start in the big logical array.

b - the ByteBuff to transfer from or to

transfer - the transfer interface.

Returns:

the length of bytes we transferred.

asSubByteBuffers

public ByteBuffer[] asSubByteBuffers(long offset,
 int len)

Creates a sub-array from a given array of ByteBuffers from the given offset to the length specified. For eg, if there are 4 buffers forming an array each with length 10 and if we call asSubByteBuffers(5, 10) then we will create an sub-array consisting of two BBs and the first one be a BB from 'position' 5 to a 'length' 5 and the 2nd BB will be from 'position' 0 to 'length' 5.

Parameters:

offset - the position in the whole array which is composited by multiple byte buffers.

len - the length of bytes

Returns:

the underlying ByteBuffers, each ByteBuffer is a slice from the backend and will have a zero position.