org.apache.lucene.store
Class BufferedIndexInput

java.lang.Object
  org.apache.lucene.store.DataInput
      org.apache.lucene.store.IndexInput
          org.apache.lucene.store.BufferedIndexInput

All Implemented Interfaces:

Closeable, Cloneable

Direct Known Subclasses:

FSDirectory.FSIndexInput

public abstract class BufferedIndexInput
extends IndexInput

Base implementation class for buffered IndexInput.

Field Summary

protected byte[]	buffer
static int	BUFFER_SIZE Default buffer size set to 1024
static int	MERGE_BUFFER_SIZE A buffer size for merges set to 4096

Constructor Summary

BufferedIndexInput(String resourceDesc)

BufferedIndexInput(String resourceDesc, int bufferSize)
Inits BufferedIndexInput with a specific bufferSize

BufferedIndexInput(String resourceDesc, IOContext context)

Method Summary

static int	bufferSize(IOContext context) Returns default buffer sizes for the given IOContext
BufferedIndexInput	clone() Returns a clone of this stream.
protected int	flushBuffer(IndexOutput out, long numBytes) Flushes the in-memory bufer to the given output, copying at most numBytes.
int	getBufferSize() Returns buffer size.
long	getFilePointer() Returns the current position in this file, where the next read will occur.
protected void	newBuffer(byte[] newBuffer)
byte	readByte() Reads and returns a single byte.
void	readBytes(byte[] b, int offset, int len) Reads a specified number of bytes into an array at the specified offset.
void	readBytes(byte[] b, int offset, int len, boolean useBuffer) Reads a specified number of bytes into an array at the specified offset with control over whether the read should be buffered (callers who have their own buffer should pass in "false" for useBuffer).
int	readInt() Reads four bytes and returns an int.
protected abstract void	readInternal(byte[] b, int offset, int length) Expert: implements buffer refill.
long	readLong() Reads eight bytes and returns a long.
short	readShort() Reads two bytes and returns a short.
int	readVInt() Reads an int stored in variable-length format.
long	readVLong() Reads a long stored in variable-length format.
void	seek(long pos) Sets current position in this file, where the next read will occur.
protected abstract void	seekInternal(long pos) Expert: implements seek.
void	setBufferSize(int newSize) Change the buffer size used by this IndexInput

Methods inherited from class org.apache.lucene.store.IndexInput

close, length, toString

Methods inherited from class org.apache.lucene.store.DataInput

readString, readStringSet, readStringStringMap

Methods inherited from class java.lang.Object

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

Field Detail

BUFFER_SIZE

public static final int BUFFER_SIZE

Default buffer size set to 1024

See Also:

Constant Field Values

MERGE_BUFFER_SIZE

public static final int MERGE_BUFFER_SIZE

A buffer size for merges set to 4096

See Also:

Constant Field Values

buffer

protected byte[] buffer

Constructor Detail

BufferedIndexInput

public BufferedIndexInput(String resourceDesc)

BufferedIndexInput

public BufferedIndexInput(String resourceDesc,
                          IOContext context)

BufferedIndexInput

public BufferedIndexInput(String resourceDesc,
                          int bufferSize)

Inits BufferedIndexInput with a specific bufferSize

Method Detail

readByte

public final byte readByte()
                    throws IOException

Description copied from class: DataInput

Reads and returns a single byte.

Specified by:

readByte in class DataInput

Throws:

IOException

See Also:

DataOutput.writeByte(byte)

setBufferSize

public final void setBufferSize(int newSize)

Change the buffer size used by this IndexInput

newBuffer

protected void newBuffer(byte[] newBuffer)

getBufferSize

public final int getBufferSize()

Returns buffer size. @see #setBufferSize

readBytes

public final void readBytes(byte[] b,
                            int offset,
                            int len)
                     throws IOException

Description copied from class: DataInput

Reads a specified number of bytes into an array at the specified offset.

Specified by:

readBytes in class DataInput

Parameters:

b - the array to read bytes into

offset - the offset in the array to start storing bytes

len - the number of bytes to read

Throws:

IOException

See Also:

DataOutput.writeBytes(byte[],int)

readBytes

public final void readBytes(byte[] b,
                            int offset,
                            int len,
                            boolean useBuffer)
                     throws IOException

Description copied from class: DataInput

Reads a specified number of bytes into an array at the specified offset with control over whether the read should be buffered (callers who have their own buffer should pass in "false" for useBuffer). Currently only BufferedIndexInput respects this parameter.

Overrides:

readBytes in class DataInput

Parameters:

b - the array to read bytes into

offset - the offset in the array to start storing bytes

len - the number of bytes to read

useBuffer - set to false if the caller will handle buffering.

Throws:

IOException

See Also:

DataOutput.writeBytes(byte[],int)

readShort

public final short readShort()
                      throws IOException

Description copied from class: DataInput

Reads two bytes and returns a short.

Overrides:

readShort in class DataInput

Throws:

IOException

See Also:

DataOutput.writeByte(byte)

readInt

public final int readInt()
                  throws IOException

Description copied from class: DataInput

Reads four bytes and returns an int.

Overrides:

readInt in class DataInput

Throws:

IOException

See Also:

DataOutput.writeInt(int)

readLong

public final long readLong()
                    throws IOException

Description copied from class: DataInput

Reads eight bytes and returns a long.

Overrides:

readLong in class DataInput

Throws:

IOException

See Also:

DataOutput.writeLong(long)

readVInt

public final int readVInt()
                   throws IOException

Description copied from class: DataInput

Reads an int stored in variable-length format. Reads between one and five bytes. Smaller values take fewer bytes. Negative numbers are not supported.

The format is described further in DataOutput.writeVInt(int).

Overrides:

readVInt in class DataInput

Throws:

IOException

See Also:

DataOutput.writeVInt(int)

readVLong

public final long readVLong()
                     throws IOException

Description copied from class: DataInput

Reads a long stored in variable-length format. Reads between one and nine bytes. Smaller values take fewer bytes. Negative numbers are not supported.

The format is described further in DataOutput.writeVInt(int).

Overrides:

readVLong in class DataInput

Throws:

IOException

See Also:

DataOutput.writeVLong(long)

readInternal

protected abstract void readInternal(byte[] b,
                                     int offset,
                                     int length)
                              throws IOException

Expert: implements buffer refill. Reads bytes from the current position in the input.

Parameters:

b - the array to read bytes into

offset - the offset in the array to start storing bytes

length - the number of bytes to read

Throws:

IOException

getFilePointer

public final long getFilePointer()

Description copied from class: IndexInput

Returns the current position in this file, where the next read will occur.

Specified by:

getFilePointer in class IndexInput

See Also:

IndexInput.seek(long)

seek

public final void seek(long pos)
                throws IOException

Description copied from class: IndexInput

Sets current position in this file, where the next read will occur.

Specified by:

seek in class IndexInput

Throws:

IOException

See Also:

IndexInput.getFilePointer()

seekInternal

protected abstract void seekInternal(long pos)
                              throws IOException

Expert: implements seek. Sets current position in this file, where the next readInternal(byte[],int,int) will occur.

Throws:

IOException

See Also:

readInternal(byte[],int,int)

clone

public BufferedIndexInput clone()

Description copied from class: IndexInput

Returns a clone of this stream.

Clones of a stream access the same data, and are positioned at the same point as the stream they were cloned from.

Expert: Subclasses must ensure that clones may be positioned at different points in the input from each other and from the stream they were cloned from.

Warning: Lucene never closes cloned IndexInputs, it will only do this on the original one. The original instance must take care that cloned instances throw AlreadyClosedException when the original one is closed.

Overrides:

clone in class IndexInput

flushBuffer

protected final int flushBuffer(IndexOutput out,
                                long numBytes)
                         throws IOException

Flushes the in-memory bufer to the given output, copying at most numBytes.

NOTE: this method does not refill the buffer, however it does advance the buffer position.

Returns:

the number of bytes actually flushed from the in-memory buffer.

Throws:

IOException

bufferSize

public static int bufferSize(IOContext context)

Returns default buffer sizes for the given IOContext