package org.apache.lucene.store;
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import java.io.EOFException;
import java.io.IOException;
import java.nio.BufferUnderflowException;
import java.nio.ByteBuffer;
import java.util.Iterator;
import org.apache.lucene.util.WeakIdentityMap;
/**
* Base IndexInput implementation that uses an array
* of ByteBuffers to represent a file.
* <p>
* Because Java's ByteBuffer uses an int to address the
* values, it's necessary to access a file greater
* Integer.MAX_VALUE in size using multiple byte buffers.
* <p>
* For efficiency, this class requires that the buffers
* are a power-of-two (<code>chunkSizePower</code>).
*/
abstract class ByteBufferIndexInput extends IndexInput {
private ByteBuffer[] buffers;
private final long chunkSizeMask;
private final int chunkSizePower;
private int offset;
private long length;
private String sliceDescription;
private int curBufIndex;
private ByteBuffer curBuf; // redundant for speed: buffers[curBufIndex]
private boolean isClone = false;
private final WeakIdentityMap<ByteBufferIndexInput,Boolean> clones;
ByteBufferIndexInput(String resourceDescription, ByteBuffer[] buffers, long length, int chunkSizePower, boolean trackClones) throws IOException {
super(resourceDescription);
this.buffers = buffers;
this.length = length;
this.chunkSizePower = chunkSizePower;
this.chunkSizeMask = (1L << chunkSizePower) - 1L;
this.clones = trackClones ? WeakIdentityMap.<ByteBufferIndexInput,Boolean>newConcurrentHashMap() : null;
assert chunkSizePower >= 0 && chunkSizePower <= 30;
assert (length >>> chunkSizePower) < Integer.MAX_VALUE;
seek(0L);
}
@Override
public final byte readByte() throws IOException {
try {
return curBuf.get();
} catch (BufferUnderflowException e) {
do {
curBufIndex++;
if (curBufIndex >= buffers.length) {
throw new EOFException("read past EOF: " + this);
}
curBuf = buffers[curBufIndex];
curBuf.position(0);
} while (!curBuf.hasRemaining());
return curBuf.get();
} catch (NullPointerException npe) {
throw new AlreadyClosedException("Already closed: " + this);
}
}
@Override
public final void readBytes(byte[] b, int offset, int len) throws IOException {
try {
curBuf.get(b, offset, len);
} catch (BufferUnderflowException e) {
int curAvail = curBuf.remaining();
while (len > curAvail) {
curBuf.get(b, offset, curAvail);
len -= curAvail;
offset += curAvail;
curBufIndex++;
if (curBufIndex >= buffers.length) {
throw new EOFException("read past EOF: " + this);
}
curBuf = buffers[curBufIndex];
curBuf.position(0);
curAvail = curBuf.remaining();
}
curBuf.get(b, offset, len);
} catch (NullPointerException npe) {
throw new AlreadyClosedException("Already closed: " + this);
}
}
@Override
public final short readShort() throws IOException {
try {
return curBuf.getShort();
} catch (BufferUnderflowException e) {
return super.readShort();
} catch (NullPointerException npe) {
throw new AlreadyClosedException("Already closed: " + this);
}
}
@Override
public final int readInt() throws IOException {
try {
return curBuf.getInt();
} catch (BufferUnderflowException e) {
return super.readInt();
} catch (NullPointerException npe) {
throw new AlreadyClosedException("Already closed: " + this);
}
}
@Override
public final long readLong() throws IOException {
try {
return curBuf.getLong();
} catch (BufferUnderflowException e) {
return super.readLong();
} catch (NullPointerException npe) {
throw new AlreadyClosedException("Already closed: " + this);
}
}
@Override
public final long getFilePointer() {
try {
return (((long) curBufIndex) << chunkSizePower) + curBuf.position() - offset;
} catch (NullPointerException npe) {
throw new AlreadyClosedException("Already closed: " + this);
}
}
@Override
public final void seek(long pos) throws IOException {
// necessary in case offset != 0 and pos < 0, but pos >= -offset
if (pos < 0L) {
throw new IllegalArgumentException("Seeking to negative position: " + this);
}
pos += offset;
// we use >> here to preserve negative, so we will catch AIOOBE,
// in case pos + offset overflows.
final int bi = (int) (pos >> chunkSizePower);
try {
final ByteBuffer b = buffers[bi];
b.position((int) (pos & chunkSizeMask));
// write values, on exception all is unchanged
this.curBufIndex = bi;
this.curBuf = b;
} catch (ArrayIndexOutOfBoundsException aioobe) {
throw new EOFException("seek past EOF: " + this);
} catch (IllegalArgumentException iae) {
throw new EOFException("seek past EOF: " + this);
} catch (NullPointerException npe) {
throw new AlreadyClosedException("Already closed: " + this);
}
}
@Override
public final long length() {
return length;
}
@Override
public final ByteBufferIndexInput clone() {
final ByteBufferIndexInput clone = buildSlice(0L, this.length);
try {
clone.seek(getFilePointer());
} catch(IOException ioe) {
throw new RuntimeException("Should never happen: " + this, ioe);
}
return clone;
}
/**
* Creates a slice of this index input, with the given description, offset, and length. The slice is seeked to the beginning.
*/
public final ByteBufferIndexInput slice(String sliceDescription, long offset, long length) {
if (isClone) { // well we could, but this is stupid
throw new IllegalStateException("cannot slice() " + sliceDescription + " from a cloned IndexInput: " + this);
}
final ByteBufferIndexInput clone = buildSlice(offset, length);
clone.sliceDescription = sliceDescription;
try {
clone.seek(0L);
} catch(IOException ioe) {
throw new RuntimeException("Should never happen: " + this, ioe);
}
return clone;
}
private ByteBufferIndexInput buildSlice(long offset, long length) {
if (buffers == null) {
throw new AlreadyClosedException("Already closed: " + this);
}
if (offset < 0 || length < 0 || offset+length > this.length) {
throw new IllegalArgumentException("slice() " + sliceDescription + " out of bounds: offset=" + offset + ",length=" + length + ",fileLength=" + this.length + ": " + this);
}
// include our own offset into the final offset:
offset += this.offset;
final ByteBufferIndexInput clone = (ByteBufferIndexInput)super.clone();
clone.isClone = true;
// we keep clone.clones, so it shares the same map with original and we have no additional cost on clones
assert clone.clones == this.clones;
clone.buffers = buildSlice(buffers, offset, length);
clone.offset = (int) (offset & chunkSizeMask);
clone.length = length;
// register the new clone in our clone list to clean it up on closing:
if (clones != null) {
this.clones.put(clone, Boolean.TRUE);
}
return clone;
}
/** Returns a sliced view from a set of already-existing buffers:
* the last buffer's limit() will be correct, but
* you must deal with offset separately (the first buffer will not be adjusted) */
private ByteBuffer[] buildSlice(ByteBuffer[] buffers, long offset, long length) {
final long sliceEnd = offset + length;
final int startIndex = (int) (offset >>> chunkSizePower);
final int endIndex = (int) (sliceEnd >>> chunkSizePower);
// we always allocate one more slice, the last one may be a 0 byte one
final ByteBuffer slices[] = new ByteBuffer[endIndex - startIndex + 1];
for (int i = 0; i < slices.length; i++) {
slices[i] = buffers[startIndex + i].duplicate();
}
// set the last buffer's limit for the sliced view.
slices[slices.length - 1].limit((int) (sliceEnd & chunkSizeMask));
return slices;
}
private void unsetBuffers() {
buffers = null;
curBuf = null;
curBufIndex = 0;
}
@Override
public final void close() throws IOException {
try {
if (buffers == null) return;
// make local copy, then un-set early
final ByteBuffer[] bufs = buffers;
unsetBuffers();
if (clones != null) {
clones.remove(this);
}
if (isClone) return;
// for extra safety unset also all clones' buffers:
if (clones != null) {
for (Iterator<ByteBufferIndexInput> it = this.clones.keyIterator(); it.hasNext();) {
final ByteBufferIndexInput clone = it.next();
assert clone.isClone;
clone.unsetBuffers();
}
this.clones.clear();
}
for (final ByteBuffer b : bufs) {
freeBuffer(b);
}
} finally {
unsetBuffers();
}
}
/**
* Called when the contents of a buffer will be no longer needed.
*/
protected abstract void freeBuffer(ByteBuffer b) throws IOException;
@Override
public final String toString() {
if (sliceDescription != null) {
return super.toString() + " [slice=" + sliceDescription + "]";
} else {
return super.toString();
}
}
}