org.apache.hadoop.hbase.util

Class ByteBufferArray

java.lang.Object

org.apache.hadoop.hbase.util.ByteBufferArray

@InterfaceAudience.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

Field Summary

Fields

Modifier and Type	Field and Description
static int	DEFAULT_BUFFER_SIZE

Constructor Summary

Constructors

Constructor and Description
ByteBufferArray(long capacity, ByteBufferAllocator allocator) We allocate a number of byte buffers as the capacity.

Method Summary

Modifier and Type	Method and 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.
int	read(long offset, ByteBuff dst) Transfers bytes from this buffers array into the given destination ByteBuff
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 Detail

DEFAULT_BUFFER_SIZE

public static final int DEFAULT_BUFFER_SIZE

See Also:

Constant Field Values

Constructor Detail

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

Method Detail

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

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.