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

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
private static class	ByteBufferArray.BufferCreatorCallable A callable that creates buffers of the specified length either onheap/offheap using the ByteBufferAllocator
private static interface	ByteBufferArray.Visitor

Field Summary

Fields

Modifier and Type	Field and Description
(package private) int	bufferCount
(package private) ByteBuffer[]	buffers
private int	bufferSize
static int	DEFAULT_BUFFER_SIZE
private static ByteBufferArray.Visitor	GET_MULTIPLE_VISTOR
private static org.slf4j.Logger	LOG
private static ByteBufferArray.Visitor	PUT_MULTIPLE_VISITOR

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
ByteBuff	asSubByteBuff(long offset, int len) Creates a ByteBuff from a given array of ByteBuffers from the given offset to the length specified.
(package private) void	createBuffers(ByteBufferAllocator allocator)
int	getMultiple(long start, int len, byte[] dstArray) Transfers bytes from this buffer array into the given destination array
int	getMultiple(long start, int len, byte[] dstArray, int dstOffset) Transfers bytes from this buffer array into the given destination array
(package private) int	getThreadCount()
(package private) void	multiple(long start, int len, byte[] array, int arrayOffset, ByteBufferArray.Visitor visitor) Access(read or write) this buffer array with a position and length as the given array.
void	putMultiple(long start, int len, byte[] srcArray) Transfers bytes from the given source array into this buffer array
void	putMultiple(long start, int len, byte[] srcArray, int srcOffset) Transfers bytes from the given source array into this buffer array
private long	roundUp(long n, long to)

Methods inherited from class java.lang.Object

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

Field Detail

LOG

private static final org.slf4j.Logger LOG

DEFAULT_BUFFER_SIZE

public static final int DEFAULT_BUFFER_SIZE

See Also:

Constant Field Values

buffers

ByteBuffer[] buffers

bufferSize

private int bufferSize

bufferCount

int bufferCount

GET_MULTIPLE_VISTOR

private static final ByteBufferArray.Visitor GET_MULTIPLE_VISTOR

PUT_MULTIPLE_VISITOR

private static final ByteBufferArray.Visitor PUT_MULTIPLE_VISITOR

Constructor Detail

ByteBufferArray

public ByteBufferArray(long capacity,
                       ByteBufferAllocator allocator)
                throws IOException

We allocate a number of byte buffers as the capacity. In order not to out of the array bounds for the last byte(see multiple(long, int, byte[], int, org.apache.hadoop.hbase.util.ByteBufferArray.Visitor)), we will allocate one additional buffer with capacity 0;

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

createBuffers

void createBuffers(ByteBufferAllocator allocator)
            throws IOException

Throws:

IOException

getThreadCount

int getThreadCount()

roundUp

private long roundUp(long n,
                     long to)

getMultiple

public int getMultiple(long start,
                       int len,
                       byte[] dstArray)

Transfers bytes from this buffer array into the given destination array

Parameters:

start - start position in the ByteBufferArray

len - The maximum number of bytes to be written to the given array

dstArray - The array into which bytes are to be written

Returns:

number of bytes read

getMultiple

public int getMultiple(long start,
                       int len,
                       byte[] dstArray,
                       int dstOffset)

Transfers bytes from this buffer array into the given destination array

Parameters:

start - start offset of this buffer array

len - The maximum number of bytes to be written to the given array

dstArray - The array into which bytes are to be written

dstOffset - The offset within the given array of the first byte to be written

Returns:

number of bytes read

putMultiple

public void putMultiple(long start,
                        int len,
                        byte[] srcArray)

Transfers bytes from the given source array into this buffer array

Parameters:

start - start offset of this buffer array

len - The maximum number of bytes to be read from the given array

srcArray - The array from which bytes are to be read

putMultiple

public void putMultiple(long start,
                        int len,
                        byte[] srcArray,
                        int srcOffset)

Transfers bytes from the given source array into this buffer array

Parameters:

start - start offset of this buffer array

len - The maximum number of bytes to be read from the given array

srcArray - The array from which bytes are to be read

srcOffset - The offset within the given array of the first byte to be read

multiple

void multiple(long start,
              int len,
              byte[] array,
              int arrayOffset,
              ByteBufferArray.Visitor visitor)

Access(read or write) this buffer array with a position and length as the given array. Here we will only lock one buffer even if it may be need visit several buffers. The consistency is guaranteed by the caller.

Parameters:

start - start offset of this buffer array

len - The maximum number of bytes to be accessed

array - The array from/to which bytes are to be read/written

arrayOffset - The offset within the given array of the first byte to be read or written

visitor - implement of how to visit the byte buffer

asSubByteBuff

public ByteBuff asSubByteBuff(long offset,
                              int len)

Creates a ByteBuff 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 asSubBuffer(5, 10) then we will create an MBB 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 -

len -

Returns:

a ByteBuff formed from the underlying ByteBuffers