org.apache.hadoop.hbase.io.util

Class BlockIOUtils

java.lang.Object

org.apache.hadoop.hbase.io.util.BlockIOUtils

@InterfaceAudience.Private
public final class BlockIOUtils
extends Object

Method Summary

Modifier and Type	Method and Description
static boolean	isByteBufferReadable(org.apache.hadoop.fs.FSDataInputStream is)
static boolean	preadWithExtra(ByteBuff buff, org.apache.hadoop.fs.FSDataInputStream dis, long position, int necessaryLen, int extraLen) Read from an input stream at least necessaryLen and if possible, extraLen also if available.
static void	readFully(ByteBuff buf, org.apache.hadoop.fs.FSDataInputStream dis, int length) Read length bytes into ByteBuffers directly.
static void	readFullyWithHeapBuffer(InputStream in, ByteBuff out, int length) Copying bytes from InputStream to ByteBuff by using an temporary heap byte[] (default size is 1024 now).
static boolean	readWithExtra(ByteBuff buf, org.apache.hadoop.fs.FSDataInputStream dis, int necessaryLen, int extraLen) Read bytes into ByteBuffers directly, those buffers either contains the extraLen bytes or only contains necessaryLen bytes, which depends on how much bytes do the last time we read.

Methods inherited from class java.lang.Object

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

Method Detail

isByteBufferReadable

public static boolean isByteBufferReadable(org.apache.hadoop.fs.FSDataInputStream is)

readFully

public static void readFully(ByteBuff buf,
                             org.apache.hadoop.fs.FSDataInputStream dis,
                             int length)
                      throws IOException

Read length bytes into ByteBuffers directly.

Parameters:

buf - the destination ByteBuff

dis - the HDFS input stream which implement the ByteBufferReadable interface.

length - bytes to read.

Throws:

IOException - exception to throw if any error happen

readFullyWithHeapBuffer

public static void readFullyWithHeapBuffer(InputStream in,
                                           ByteBuff out,
                                           int length)
                                    throws IOException

Copying bytes from InputStream to ByteBuff by using an temporary heap byte[] (default size is 1024 now).

Parameters:

in - the InputStream to read

out - the destination ByteBuff

length - to read

Throws:

IOException - if any io error encountered.

readWithExtra

public static boolean readWithExtra(ByteBuff buf,
                                    org.apache.hadoop.fs.FSDataInputStream dis,
                                    int necessaryLen,
                                    int extraLen)
                             throws IOException

Read bytes into ByteBuffers directly, those buffers either contains the extraLen bytes or only contains necessaryLen bytes, which depends on how much bytes do the last time we read.

Parameters:

buf - the destination ByteBuff.

dis - input stream to read.

necessaryLen - bytes which we must read

extraLen - bytes which we may read

Returns:

if the returned flag is true, then we've finished to read the extraLen into our ByteBuffers, otherwise we've not read the extraLen bytes yet.

Throws:

IOException - if failed to read the necessary bytes.

preadWithExtra

public static boolean preadWithExtra(ByteBuff buff,
                                     org.apache.hadoop.fs.FSDataInputStream dis,
                                     long position,
                                     int necessaryLen,
                                     int extraLen)
                              throws IOException

Read from an input stream at least necessaryLen and if possible, extraLen also if available. Analogous to IOUtils.readFully(InputStream, byte[], int, int), but uses positional read and specifies a number of "extra" bytes that would be desirable but not absolutely necessary to read.

Parameters:

buff - ByteBuff to read into.

dis - the input stream to read from

position - the position within the stream from which to start reading

necessaryLen - the number of bytes that are absolutely necessary to read

extraLen - the number of extra bytes that would be nice to read

Returns:

true if and only if extraLen is > 0 and reading those extra bytes was successful

Throws:

IOException - if failed to read the necessary bytes