Package 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, AutoCloseable, Cloneable, RandomAccessInput

Direct Known Subclasses:

BufferedIndexInput.SlicedIndexInput, NIOFSDirectory.NIOFSIndexInput, RAFDirectory.RAFIndexInput, SimpleFSDirectory.SimpleFSIndexInput, WindowsDirectory.WindowsIndexInput

public abstract class BufferedIndexInput
extends IndexInput
implements RandomAccessInput

Base implementation class for buffered IndexInput.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private static final class	BufferedIndexInput.SlicedIndexInput	Implementation of an IndexInput that reads from a portion of a file.

Field Summary

Fields

Modifier and Type	Field	Description
private ByteBuffer	buffer
static final int	BUFFER_SIZE	Default buffer size set to 1024.
private int	bufferSize
private long	bufferStart
private static final ByteBuffer	EMPTY_BYTEBUFFER
static final int	MERGE_BUFFER_SIZE	A buffer size for merges set to 4096.
static final int	MIN_BUFFER_SIZE	Minimum buffer size allowed

Constructor Summary

Constructors

Constructor	Description
BufferedIndexInput(String resourceDesc)
BufferedIndexInput(String resourceDesc, int bufferSize)	Inits BufferedIndexInput with a specific bufferSize
BufferedIndexInput(String resourceDesc, IOContext context)

Method Summary

Modifier and Type	Method	Description
static int	bufferSize(IOContext context)	Returns default buffer sizes for the given IOContext
private void	checkBufferSize(int bufferSize)
BufferedIndexInput	clone()	Returns a clone of this stream.
final int	getBufferSize()	Returns buffer size.
final long	getFilePointer()	Returns the current position in this file, where the next read will occur.
final byte	readByte()	Reads and returns a single byte.
final byte	readByte(long pos)	Reads a byte at the given position in the file
final void	readBytes(byte[] b, int offset, int len)	Reads a specified number of bytes into an array at the specified offset.
final 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).
final int	readInt()	Reads four bytes and returns an int.
final int	readInt(long pos)	Reads an integer at the given position in the file
protected abstract void	readInternal(ByteBuffer b)	Expert: implements buffer refill.
final long	readLong()	Reads eight bytes and returns a long.
final long	readLong(long pos)	Reads a long at the given position in the file
final short	readShort()	Reads two bytes and returns a short.
final short	readShort(long pos)	Reads a short at the given position in the file
final int	readVInt()	Reads an int stored in variable-length format.
final long	readVLong()	Reads a long stored in variable-length format.
private void	refill()
final 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.
final void	setBufferSize(int newSize)	Change the buffer size used by this IndexInput
IndexInput	slice(String sliceDescription, long offset, long length)	Creates a slice of this index input, with the given description, offset, and length.
static BufferedIndexInput	wrap(String sliceDescription, IndexInput other, long offset, long length)	Wraps a portion of another IndexInput with buffering.

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

close, getFullSliceDescription, length, randomAccessSlice, toString

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

readLELongs, readMapOfStrings, readSetOfStrings, readString, readZInt, readZLong, skipBytes

Methods inherited from class java.lang.Object

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

Field Details

EMPTY_BYTEBUFFER

private static final ByteBuffer EMPTY_BYTEBUFFER

BUFFER_SIZE

public static final int BUFFER_SIZE

Default buffer size set to 1024.

See Also:

• Constant Field Values

MIN_BUFFER_SIZE

public static final int MIN_BUFFER_SIZE

Minimum buffer size allowed

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

bufferSize

private int bufferSize

buffer

private ByteBuffer buffer

bufferStart

private long bufferStart

Constructor Details

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 Details

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

getBufferSize

public final int getBufferSize()

Returns buffer size. @see #setBufferSize

checkBufferSize

private void checkBufferSize(int bufferSize)

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 supported, but should be avoided.

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)

readByte

public final byte readByte(long pos)
                    throws IOException

Description copied from interface: RandomAccessInput

Reads a byte at the given position in the file

Specified by:

readByte in interface RandomAccessInput

Throws:

IOException

See Also:

• DataInput.readByte()

readShort

public final short readShort(long pos)
                      throws IOException

Description copied from interface: RandomAccessInput

Reads a short at the given position in the file

Specified by:

readShort in interface RandomAccessInput

Throws:

IOException

See Also:

• DataInput.readShort()

readInt

public final int readInt(long pos)
                  throws IOException

Description copied from interface: RandomAccessInput

Reads an integer at the given position in the file

Specified by:

readInt in interface RandomAccessInput

Throws:

IOException

See Also:

• DataInput.readInt()

readLong

public final long readLong(long pos)
                    throws IOException

Description copied from interface: RandomAccessInput

Reads a long at the given position in the file

Specified by:

readLong in interface RandomAccessInput

Throws:

IOException

See Also:

• DataInput.readLong()

refill

private void refill()
             throws IOException

Throws:

IOException

readInternal

protected abstract void readInternal(ByteBuffer b)
                              throws IOException

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

Parameters:

b - the buffer to read bytes into

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. If this is beyond the end of the file then this will throw EOFException and then the stream is in an undetermined state.

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(ByteBuffer) will occur.

Throws:

IOException

See Also:

• readInternal(ByteBuffer)

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 call IndexInput.close() on the original object.

If you access the cloned IndexInput after closing the original object, any readXXX methods will throw AlreadyClosedException.

This method is NOT thread safe, so if the current IndexInput is being used by one thread while clone is called by another, disaster could strike.

Overrides:

clone in class IndexInput

slice

public IndexInput slice(String sliceDescription,
 long offset,
 long length)
                 throws IOException

Description copied from class: IndexInput

Creates a slice of this index input, with the given description, offset, and length. The slice is sought to the beginning.

Specified by:

slice in class IndexInput

Throws:

IOException

bufferSize

public static int bufferSize(IOContext context)

Returns default buffer sizes for the given IOContext

wrap

public static BufferedIndexInput wrap(String sliceDescription,
 IndexInput other,
 long offset,
 long length)

Wraps a portion of another IndexInput with buffering.

Please note: This is in most cases ineffective, because it may double buffer!