wt.util
Class BlockDataInputStream

java.lang.Object
  java.io.InputStream
      java.io.FilterInputStream
          wt.util.BlockDataInputStream

public class BlockDataInputStream

extends FilterInputStream

An input stream filter used to read a stream nested on another stream by the BlockDataOutputStream class. The filter will return EOF at the end of the nested stream without reading past the end of the nested stream.

For best read through performance when layered over buffered streams, the read length should be 4 bytes larger than the blocks that were written to allow read ahead of the next block header.

Reads may block until a data block is fully read as long as read buffers are large enough to receive the entire block. Multiple blocks may be read at once if block headers are received while reading. If a full block has been read but the next block header was not received, the current data is returned without further blocking. The result is that the number of bytes read at once should always meet or exceed the number of bytes that were written in a block if the read buffer is large enough.

Nested Class Summary

static class

BlockDataInputStream.Test

Field Summary

private static boolean	DEBUG
private boolean	eof
private byte[]	header
private int	offset
private int	remaining
private int	unused

Fields inherited from class java.io.FilterInputStream

in

Fields inherited from class java.io.InputStream

Constructor Summary

BlockDataInputStream(InputStream input_stream)

Method Summary

int	available() Return how many bytes remain in the current block.
boolean	markSupported() Returns false.
private void	nextBlock()
int	read()
int	read(byte[] buf, int off, int len)
private int	readFully(byte[] buf, int off, int min_len, int max_len)

Methods inherited from class java.io.FilterInputStream

close, mark, read, reset, skip

Methods inherited from class java.lang.Object

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

Field Detail

remaining

private int remaining

eof

private boolean eof

header

private byte[] header

unused

private int unused

offset

private int offset

DEBUG

private static final boolean DEBUG

See Also:

Constant Field Values

Constructor Detail

BlockDataInputStream

public BlockDataInputStream(InputStream input_stream)

Method Detail

read

public int read()
         throws IOException

Throws:

IOException

read

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

Throws:

IOException

readFully

private int readFully(byte[] buf,
                      int off,
                      int min_len,
                      int max_len)
               throws IOException

Throws:

IOException

nextBlock

private void nextBlock()
                throws IOException

Throws:

IOException

available

public int available()
              throws IOException

Return how many bytes remain in the current block. This does not necessarily imply that reads will not block while reading the remainder of the block, but it indicates that the data has been sent.

Throws:

IOException

markSupported

public boolean markSupported()

Returns false.