Package org.apache.lucene.store

Class ByteBufferGuard

java.lang.Object

org.apache.lucene.store.ByteBufferGuard

final class ByteBufferGuard
extends java.lang.Object

A guard that is created for every ByteBufferIndexInput that tries on best effort to reject any access to the ByteBuffer behind, once it is unmapped. A single instance of this is used for the original and all clones, so once the original is closed and unmapped all clones also throw AlreadyClosedException, triggered by a NullPointerException.

This code tries to hopefully flush any CPU caches using a store-store barrier. It also yields the current thread to give other threads a chance to finish in-flight requests...

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
(package private) static interface	ByteBufferGuard.BufferCleaner	Pass in an implementation of this interface to cleanup ByteBuffers.

Field Summary

Fields

Modifier and Type	Field	Description
private java.util.concurrent.atomic.AtomicInteger	barrier	Used as a store-store barrier; see comments below!
private ByteBufferGuard.BufferCleaner	cleaner
private boolean	invalidated	Not volatile; see comments on visibility below!
private java.lang.String	resourceDescription

Constructor Summary

Constructors

Constructor	Description
ByteBufferGuard(java.lang.String resourceDescription, ByteBufferGuard.BufferCleaner cleaner)	Creates an instance to be used for a single ByteBufferIndexInput which must be shared by all of its clones.

Method Summary

Modifier and Type	Method	Description
private void	ensureValid()
byte	getByte(java.nio.ByteBuffer receiver)
byte	getByte(java.nio.ByteBuffer receiver, int pos)
void	getBytes(java.nio.ByteBuffer receiver, byte[] dst, int offset, int length)
int	getInt(java.nio.ByteBuffer receiver)
int	getInt(java.nio.ByteBuffer receiver, int pos)
long	getLong(java.nio.ByteBuffer receiver)
long	getLong(java.nio.ByteBuffer receiver, int pos)
void	getLongs(java.nio.LongBuffer receiver, long[] dst, int offset, int length)
short	getShort(java.nio.ByteBuffer receiver)
short	getShort(java.nio.ByteBuffer receiver, int pos)
void	invalidateAndUnmap(java.nio.ByteBuffer... bufs)	Invalidates this guard and unmaps (if supported).

Methods inherited from class java.lang.Object

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

Field Detail

resourceDescription

private final java.lang.String resourceDescription

cleaner

private final ByteBufferGuard.BufferCleaner cleaner

invalidated

private boolean invalidated

Not volatile; see comments on visibility below!

barrier

private final java.util.concurrent.atomic.AtomicInteger barrier

Used as a store-store barrier; see comments below!

Constructor Detail

ByteBufferGuard

public ByteBufferGuard(java.lang.String resourceDescription,
                       ByteBufferGuard.BufferCleaner cleaner)

Creates an instance to be used for a single ByteBufferIndexInput which must be shared by all of its clones.

Method Detail

invalidateAndUnmap

public void invalidateAndUnmap(java.nio.ByteBuffer... bufs)
                        throws java.io.IOException

Invalidates this guard and unmaps (if supported).

Throws:

java.io.IOException

ensureValid

private void ensureValid()

getBytes

public void getBytes(java.nio.ByteBuffer receiver,
                     byte[] dst,
                     int offset,
                     int length)

getByte

public byte getByte(java.nio.ByteBuffer receiver)

getShort

public short getShort(java.nio.ByteBuffer receiver)

getInt

public int getInt(java.nio.ByteBuffer receiver)

getLong

public long getLong(java.nio.ByteBuffer receiver)

getByte

public byte getByte(java.nio.ByteBuffer receiver,
                    int pos)

getShort

public short getShort(java.nio.ByteBuffer receiver,
                      int pos)

getInt

public int getInt(java.nio.ByteBuffer receiver,
                  int pos)

getLong

public long getLong(java.nio.ByteBuffer receiver,
                    int pos)

getLongs

public void getLongs(java.nio.LongBuffer receiver,
                     long[] dst,
                     int offset,
                     int length)