alluxio.client.file

Class PositionReadFileInStream

java.lang.Object

java.io.InputStream

alluxio.client.file.FileInStream

alluxio.client.file.PositionReadFileInStream

All Implemented Interfaces:

BoundedStream, CanUnbuffer, PositionedReadable, Positioned, Seekable, Closeable, AutoCloseable

@NotThreadSafe
public class PositionReadFileInStream
extends FileInStream

Implementation of FileInStream that reads from a dora cache if possible.

Constructor Summary

Constructors

Constructor and Description
PositionReadFileInStream(PositionReader reader, long length) Constructor.

Method Summary

Modifier and Type	Method and Description
void	close()
long	getPos()
int	positionedRead(long position, byte[] buffer, int offset, int len) Reads up to the specified number of bytes, from a given position within a file, and return the number of bytes read.
int	read(byte[] b, int off, int len)
int	read(ByteBuffer byteBuffer, int off, int len) Reads up to len bytes of data from the input stream into the byte buffer.
long	remaining()
void	seek(long pos) Moves the starting read position of the stream to the specified position which is relative to the start of the stream.
long	skip(long n)

Methods inherited from class alluxio.client.file.FileInStream

read, read, read, unbuffer

Methods inherited from class java.io.InputStream

available, mark, markSupported, reset

Methods inherited from class java.lang.Object

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

Constructor Detail

PositionReadFileInStream

public PositionReadFileInStream(PositionReader reader,
                                long length)

Constructor.

Parameters:

reader -

length -

Method Detail

remaining

public long remaining()

Returns:

the remaining number of bytes left in the stream, starting at the current position

read

public int read(byte[] b,
                int off,
                int len)
         throws IOException

Overrides:

read in class FileInStream

Throws:

IOException

read

public int read(ByteBuffer byteBuffer,
                int off,
                int len)
         throws IOException

Description copied from class: FileInStream

Reads up to len bytes of data from the input stream into the byte buffer.

Overrides:

read in class FileInStream

Parameters:

byteBuffer - the buffer into which the data is read

off - the start offset in the buffer at which the data is written

len - the maximum number of bytes to read

Returns:

the total number of bytes read into the buffer, or -1 if there is no more data because the end of the stream has been reached

Throws:

IOException

positionedRead

public int positionedRead(long position,
                          byte[] buffer,
                          int offset,
                          int len)
                   throws IOException

Description copied from interface: PositionedReadable

Reads up to the specified number of bytes, from a given position within a file, and return the number of bytes read. This does not change the current offset of a file, and is thread-safe. Not all implementations meet the thread safety requirement. According to the documentation of the PositionedReadable interface in Hadoop, those that do not meet the requirement cannot be used as a backing store for some applications, such as Apache HBase. All implementations of this interface in Alluxio must meet the thread safety requirement.

Parameters:

position - position within file

buffer - destination buffer

offset - offset in the buffer

len - number of bytes to read

Returns:

actual number of bytes read; -1 means "EOF";

Throws:

IOException

getPos

public long getPos()
            throws IOException

Returns:

the current position

Throws:

IOException

seek

public void seek(long pos)
          throws IOException

Description copied from interface: Seekable

Moves the starting read position of the stream to the specified position which is relative to the start of the stream. Seeking to a position before the current read position is supported.

Parameters:

pos - the position to seek to, it must be between 0 and the end of the stream - 1

Throws:

IOException

skip

public long skip(long n)
          throws IOException

Overrides:

skip in class InputStream

Throws:

IOException

close

public void close()
           throws IOException

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Overrides:

close in class InputStream

Throws:

IOException