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.File;
import java.io.IOException;
import java.io.RandomAccessFile;
/** A straightforward implementation of {@link FSDirectory}
* using java.io.RandomAccessFile. However, this class has
* poor concurrent performance (multiple threads will
* bottleneck) as it synchronizes when multiple threads
* read from the same file. It's usually better to use
* {@link NIOFSDirectory} or {@link MMapDirectory} instead. */
public class SimpleFSDirectory extends FSDirectory {
/** Create a new SimpleFSDirectory for the named location.
*
* @param path the path of the directory
* @param lockFactory the lock factory to use, or null for the default
* ({@link NativeFSLockFactory});
* @throws IOException if there is a low-level I/O error
*/
public SimpleFSDirectory(File path, LockFactory lockFactory) throws IOException {
super(path, lockFactory);
}
/** Create a new SimpleFSDirectory for the named location and {@link NativeFSLockFactory}.
*
* @param path the path of the directory
* @throws IOException if there is a low-level I/O error
*/
public SimpleFSDirectory(File path) throws IOException {
super(path, null);
}
/** Creates an IndexInput for the file with the given name. */
@Override
public IndexInput openInput(String name, IOContext context) throws IOException {
ensureOpen();
final File path = new File(directory, name);
RandomAccessFile raf = new RandomAccessFile(path, "r");
return new SimpleFSIndexInput("SimpleFSIndexInput(path=\"" + path.getPath() + "\")", raf, context);
}
@Override
public IndexInputSlicer createSlicer(final String name,
final IOContext context) throws IOException {
ensureOpen();
final File file = new File(getDirectory(), name);
final RandomAccessFile descriptor = new RandomAccessFile(file, "r");
return new IndexInputSlicer() {
@Override
public void close() throws IOException {
descriptor.close();
}
@Override
public IndexInput openSlice(String sliceDescription, long offset, long length) {
return new SimpleFSIndexInput("SimpleFSIndexInput(" + sliceDescription + " in path=\"" + file.getPath() + "\" slice=" + offset + ":" + (offset+length) + ")", descriptor, offset,
length, BufferedIndexInput.bufferSize(context));
}
};
}
/**
* Reads bytes with {@link RandomAccessFile#seek(long)} followed by
* {@link RandomAccessFile#read(byte[], int, int)}.
*/
protected static class SimpleFSIndexInput extends BufferedIndexInput {
/**
* The maximum chunk size is 8192 bytes, because {@link RandomAccessFile} mallocs
* a native buffer outside of stack if the read buffer size is larger.
*/
private static final int CHUNK_SIZE = 8192;
/** the file channel we will read from */
protected final RandomAccessFile file;
/** is this instance a clone and hence does not own the file to close it */
boolean isClone = false;
/** start offset: non-zero in the slice case */
protected final long off;
/** end offset (start+length) */
protected final long end;
public SimpleFSIndexInput(String resourceDesc, RandomAccessFile file, IOContext context) throws IOException {
super(resourceDesc, context);
this.file = file;
this.off = 0L;
this.end = file.length();
}
public SimpleFSIndexInput(String resourceDesc, RandomAccessFile file, long off, long length, int bufferSize) {
super(resourceDesc, bufferSize);
this.file = file;
this.off = off;
this.end = off + length;
this.isClone = true;
}
@Override
public void close() throws IOException {
if (!isClone) {
file.close();
}
}
@Override
public SimpleFSIndexInput clone() {
SimpleFSIndexInput clone = (SimpleFSIndexInput)super.clone();
clone.isClone = true;
return clone;
}
@Override
public final long length() {
return end - off;
}
/** IndexInput methods */
@Override
protected void readInternal(byte[] b, int offset, int len)
throws IOException {
synchronized (file) {
long position = off + getFilePointer();
file.seek(position);
int total = 0;
if (position + len > end) {
throw new EOFException("read past EOF: " + this);
}
try {
while (total < len) {
final int toRead = Math.min(CHUNK_SIZE, len - total);
final int i = file.read(b, offset + total, toRead);
if (i < 0) { // be defensive here, even though we checked before hand, something could have changed
throw new EOFException("read past EOF: " + this + " off: " + offset + " len: " + len + " total: " + total + " chunkLen: " + toRead + " end: " + end);
}
assert i > 0 : "RandomAccessFile.read with non zero-length toRead must always read at least one byte";
total += i;
}
assert total == len;
} catch (IOException ioe) {
throw new IOException(ioe.getMessage() + ": " + this, ioe);
}
}
}
@Override
protected void seekInternal(long position) {
}
boolean isFDValid() throws IOException {
return file.getFD().valid();
}
}
}