alluxio.util.io

Class BufferUtils

java.lang.Object

alluxio.util.io.BufferUtils

@ThreadSafe
public final class BufferUtils
extends Object

Utilities related to buffers, not only ByteBuffer.

Method Summary

Modifier and Type	Method and Description
static int	byteToInt(byte b) Converts a byte to an integer.
static void	cleanDirectBuffer(ByteBuffer buffer) Forces to unmap a direct buffer if this buffer is no longer used.
static ByteBuffer	cloneByteBuffer(ByteBuffer buf) Clones a ByteBuffer.
static List<ByteBuffer>	cloneByteBufferList(List<ByteBuffer> source) Clones a list of ByteBuffers.
static boolean	equalConstantByteArray(byte value, int len, byte[] arr) Checks if the given byte array starts with a constant sequence of bytes of the given value and length.
static boolean	equalIncreasingByteArray(int len, byte[] arr) Checks if the given byte array starts with an increasing sequence of bytes of the given length, starting from 0.
static boolean	equalIncreasingByteArray(int start, int len, byte[] arr) Checks if the given byte array starts with an increasing sequence of bytes of the given length, starting from the given value.
static boolean	equalIncreasingByteBuffer(int start, int len, ByteBuffer buf) Checks if the given ByteBuffer starts with an increasing sequence of bytes starting at the given value of length equal to or greater than the given length.
static void	fastCopy(ReadableByteChannel src, WritableByteChannel dest) An efficient copy between two channels with a fixed-size buffer.
static byte[]	getIncreasingByteArray(int len) Gets an increasing sequence of bytes starting at zero.
static byte[]	getIncreasingByteArray(int start, int len) Gets an increasing sequence of bytes starting with the given value.
static ByteBuffer	getIncreasingByteBuffer(int len) Gets a ByteBuffer containing an increasing sequence of bytes starting at zero.
static ByteBuffer	getIncreasingByteBuffer(int start, int len) Gets a ByteBuffer containing an increasing sequence of bytes starting at the given value.
static int	intAsUnsignedByteValue(int i) Gets the unsigned byte value of an integer.
static byte[]	newByteArrayFromByteBuffer(ByteBuffer buf) Creates a byte array from the given ByteBuffer, the position property of input ByteBuffer remains unchanged.
static void	putIntByteBuffer(ByteBuffer buf, int b) Puts a byte (the first byte of an integer) into a ByteBuffer.
static ByteBuffer	sliceByteBuffer(ByteBuffer buffer, int position) Convenience method for sliceByteBuffer(ByteBuffer, int, int) where the last parameter is the number of remaining bytes in the new buffer.
static ByteBuffer	sliceByteBuffer(ByteBuffer buffer, int position, int length) Creates a new ByteBuffer sliced from a given ByteBuffer.
static void	writeBufferToFile(String path, byte[] buffer) Writes buffer to the given file path.

Methods inherited from class java.lang.Object

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

Method Detail

byteToInt

public static int byteToInt(byte b)

Converts a byte to an integer.

Parameters:

b - the byte to convert

Returns:

the integer representation of the byte

cleanDirectBuffer

public static void cleanDirectBuffer(ByteBuffer buffer)

Forces to unmap a direct buffer if this buffer is no longer used. After calling this method, this direct buffer should be discarded. This is unsafe operation and currently a work-around to avoid huge memory occupation caused by memory map.

NOTE: DirectByteBuffers are not guaranteed to be garbage-collected immediately after their references are released and may lead to OutOfMemoryError. This function helps by calling the Cleaner method of a DirectByteBuffer explicitly. See more discussion.

Parameters:

buffer - the byte buffer to be unmapped, this must be a direct buffer

cloneByteBuffer

public static ByteBuffer cloneByteBuffer(ByteBuffer buf)

Clones a ByteBuffer.

The new bytebuffer will have the same content, but the type of the bytebuffer may not be the same.

Parameters:

buf - The ByteBuffer to copy

Returns:

The new ByteBuffer

cloneByteBufferList

public static List<ByteBuffer> cloneByteBufferList(List<ByteBuffer> source)

Clones a list of ByteBuffers.

Parameters:

source - the list of ByteBuffers to copy

Returns:

the new list of ByteBuffers

putIntByteBuffer

public static void putIntByteBuffer(ByteBuffer buf,
                                    int b)

Puts a byte (the first byte of an integer) into a ByteBuffer.

Parameters:

buf - ByteBuffer to use

b - byte to put into the ByteBuffer

getIncreasingByteArray

public static byte[] getIncreasingByteArray(int len)

Gets an increasing sequence of bytes starting at zero.

Parameters:

len - the target length of the sequence

Returns:

an increasing sequence of bytes

getIncreasingByteArray

public static byte[] getIncreasingByteArray(int start,
                                            int len)

Gets an increasing sequence of bytes starting with the given value.

Parameters:

start - the starting value to use

len - the target length of the sequence

Returns:

an increasing sequence of bytes

equalConstantByteArray

public static boolean equalConstantByteArray(byte value,
                                             int len,
                                             byte[] arr)

Checks if the given byte array starts with a constant sequence of bytes of the given value and length.

Parameters:

value - the value to check for

len - the target length of the sequence

arr - the byte array to check

Returns:

true if the byte array has a prefix of length len that is a constant sequence of bytes of the given value

equalIncreasingByteArray

public static boolean equalIncreasingByteArray(int len,
                                               byte[] arr)

Checks if the given byte array starts with an increasing sequence of bytes of the given length, starting from 0.

Parameters:

len - the target length of the sequence

arr - the byte array to check

Returns:

true if the byte array has a prefix of length len that is an increasing sequence of bytes starting at zero

equalIncreasingByteArray

public static boolean equalIncreasingByteArray(int start,
                                               int len,
                                               byte[] arr)

Checks if the given byte array starts with an increasing sequence of bytes of the given length, starting from the given value. The array length must be equal to the length checked.

Parameters:

start - the starting value to use

len - the target length of the sequence

arr - the byte array to check

Returns:

true if the byte array has a prefix of length len that is an increasing sequence of bytes starting at start

getIncreasingByteBuffer

public static ByteBuffer getIncreasingByteBuffer(int len)

Gets a ByteBuffer containing an increasing sequence of bytes starting at zero.

Parameters:

len - the target length of the sequence

Returns:

ByteBuffer containing an increasing sequence of bytes

getIncreasingByteBuffer

public static ByteBuffer getIncreasingByteBuffer(int start,
                                                 int len)

Gets a ByteBuffer containing an increasing sequence of bytes starting at the given value.

Parameters:

len - the target length of the sequence

start - the starting value to use

Returns:

ByteBuffer containing an increasing sequence of bytes

equalIncreasingByteBuffer

public static boolean equalIncreasingByteBuffer(int start,
                                                int len,
                                                ByteBuffer buf)

Checks if the given ByteBuffer starts with an increasing sequence of bytes starting at the given value of length equal to or greater than the given length.

Parameters:

start - the starting value to use

len - the target length of the sequence

buf - the ByteBuffer to check

Returns:

true if the ByteBuffer has a prefix of length len that is an increasing sequence of bytes starting at start

writeBufferToFile

public static void writeBufferToFile(String path,
                                     byte[] buffer)
                              throws IOException

Writes buffer to the given file path.

Parameters:

path - file path to write the data

buffer - raw data

Throws:

IOException

fastCopy

public static void fastCopy(ReadableByteChannel src,
                            WritableByteChannel dest)
                     throws IOException

An efficient copy between two channels with a fixed-size buffer.

Parameters:

src - the source channel

dest - the destination channel

Throws:

IOException

intAsUnsignedByteValue

public static int intAsUnsignedByteValue(int i)

Gets the unsigned byte value of an integer. Useful for comparing to the result of reading from an input stream.

Parameters:

i - the integer to convert

Returns:

the integer value after casting as an unsigned byte

newByteArrayFromByteBuffer

public static byte[] newByteArrayFromByteBuffer(ByteBuffer buf)

Creates a byte array from the given ByteBuffer, the position property of input ByteBuffer remains unchanged.

Parameters:

buf - source ByteBuffer

Returns:

a newly created byte array

sliceByteBuffer

public static ByteBuffer sliceByteBuffer(ByteBuffer buffer,
                                         int position,
                                         int length)

Creates a new ByteBuffer sliced from a given ByteBuffer. The new ByteBuffer shares the content of the existing one, but with independent position/mark/limit. After slicing, the new ByteBuffer has position 0, and the input ByteBuffer is unmodified.

Parameters:

buffer - source ByteBuffer to slice

position - position in the source ByteBuffer to slice

length - length of the sliced ByteBuffer

Returns:

the sliced ByteBuffer

sliceByteBuffer

public static ByteBuffer sliceByteBuffer(ByteBuffer buffer,
                                         int position)

Convenience method for sliceByteBuffer(ByteBuffer, int, int) where the last parameter is the number of remaining bytes in the new buffer.

Parameters:

buffer - source ByteBuffer to slice

position - position in the source ByteBuffer to slice

Returns:

the sliced ByteBuffer