package org.infinispan.lucene.impl;
import java.io.IOException;
import org.apache.lucene.store.IndexInput;
import org.infinispan.lucene.ChunkCacheKey;
/**
* SingleChunkIndexInput can be used instead of InfinispanIndexInput to read a segment
* when it has a size small enough to fit in a single chunk.
* In this quite common case for some segment types we
* don't need the readLock to span multiple chunks, the pointer to the buffer is safe enough.
* This leads to an extreme simple implementation.
*
* @author Sanne Grinovero
* @since 4.0
*/
public final class SingleChunkIndexInput extends IndexInput {
private final byte[] buffer;
private int bufferPosition;
public SingleChunkIndexInput(final IndexInputContext iic) {
super(iic.fileKey.getFileName());
ChunkCacheKey key = new ChunkCacheKey(iic.fileKey.getIndexName(), iic.fileKey.getFileName(), 0, iic.fileMetadata.getBufferSize());
byte[] b = (byte[]) iic.chunksCache.get(key);
if (b == null) {
buffer = new byte[0];
}
else {
buffer = b;
}
bufferPosition = 0;
}
@Override
public void close() {
//nothing to do
}
@Override
public long getFilePointer() {
return bufferPosition;
}
@Override
public long length() {
return buffer.length;
}
@Override
public byte readByte() throws IOException {
if (bufferPosition >= buffer.length) {
throw new IOException("Read past EOF");
}
return buffer[bufferPosition++];
}
@Override
public void readBytes(final byte[] b, final int offset, final int len) throws IOException {
if (buffer.length - bufferPosition < len) {
throw new IOException("Read past EOF");
}
System.arraycopy(buffer, bufferPosition, b, offset, len);
bufferPosition+=len;
}
@Override
public void seek(final long pos) {
//Lucene might use positions larger than length(), in
//this case you have to position the pointer to eof.
bufferPosition = (int) Math.min(pos, buffer.length);
}
}