org.apache.hadoop.hdfs
Class ByteRangeInputStream

java.lang.Object
  java.io.InputStream
      org.apache.hadoop.fs.FSInputStream
          org.apache.hadoop.hdfs.ByteRangeInputStream

All Implemented Interfaces:

Closeable, org.apache.hadoop.fs.PositionedReadable, org.apache.hadoop.fs.Seekable

public abstract class ByteRangeInputStream
extends org.apache.hadoop.fs.FSInputStream

To support HTTP byte streams, a new connection to an HTTP server needs to be created each time. This class hides the complexity of those multiple connections from the client. Whenever seek() is called, a new connection is made on the successive read(). The normal input stream functions are connected to the currently active input stream.

Nested Class Summary

static class

ByteRangeInputStream.URLOpener This class wraps a URL and provides method to open connection.

Field Summary

protected long	currentPos
protected Long	fileLength
protected InputStream	in
protected ByteRangeInputStream.URLOpener	originalURL
protected ByteRangeInputStream.URLOpener	resolvedURL
protected long	startPos

Constructor Summary

ByteRangeInputStream(ByteRangeInputStream.URLOpener o, ByteRangeInputStream.URLOpener r)
Create with the specified URLOpeners.

Method Summary

void	close()
protected InputStream	getInputStream()
long	getPos() Return the current offset from the start of the file
protected abstract URL	getResolvedUrl(HttpURLConnection connection)
protected InputStream	openInputStream()
int	read()
int	read(byte[] b, int off, int len)
void	seek(long pos) Seek to the given offset from the start of the file.
boolean	seekToNewSource(long targetPos) Seeks a different copy of the data.

Methods inherited from class org.apache.hadoop.fs.FSInputStream

read, readFully, readFully

Methods inherited from class java.io.InputStream

available, mark, markSupported, read, reset, skip

Methods inherited from class java.lang.Object

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

Field Detail

in

protected InputStream in

originalURL

protected ByteRangeInputStream.URLOpener originalURL

resolvedURL

protected ByteRangeInputStream.URLOpener resolvedURL

startPos

protected long startPos

currentPos

protected long currentPos

fileLength

protected Long fileLength

Constructor Detail

ByteRangeInputStream

public ByteRangeInputStream(ByteRangeInputStream.URLOpener o,
                            ByteRangeInputStream.URLOpener r)

Create with the specified URLOpeners. Original url is used to open the stream for the first time. Resolved url is used in subsequent requests.

Parameters:

o - Original url

r - Resolved url

Method Detail

getResolvedUrl

protected abstract URL getResolvedUrl(HttpURLConnection connection)
                               throws IOException

Throws:

IOException

getInputStream

protected InputStream getInputStream()
                              throws IOException

Throws:

IOException

openInputStream

protected InputStream openInputStream()
                               throws IOException

Throws:

IOException

read

public int read()
         throws IOException

Specified by:

read in class InputStream

Throws:

IOException

read

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

Overrides:

read in class InputStream

Throws:

IOException

seek

public void seek(long pos)
          throws IOException

Seek to the given offset from the start of the file. The next read() will be from that location. Can't seek past the end of the file.

Specified by:

seek in interface org.apache.hadoop.fs.Seekable

Specified by:

seek in class org.apache.hadoop.fs.FSInputStream

Throws:

IOException

getPos

public long getPos()
            throws IOException

Return the current offset from the start of the file

Specified by:

getPos in interface org.apache.hadoop.fs.Seekable

Specified by:

getPos in class org.apache.hadoop.fs.FSInputStream

Throws:

IOException

seekToNewSource

public boolean seekToNewSource(long targetPos)
                        throws IOException

Seeks a different copy of the data. Returns true if found a new source, false otherwise.

Specified by:

seekToNewSource in interface org.apache.hadoop.fs.Seekable

Specified by:

seekToNewSource in class org.apache.hadoop.fs.FSInputStream

Throws:

IOException

close

public void close()
           throws IOException

Specified by:

close in interface Closeable

Overrides:

close in class InputStream

Throws:

IOException