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.IOException;
import java.io.FileNotFoundException;
import java.io.Serializable;
import java.util.HashMap;
import java.util.Set;
import java.util.concurrent.atomic.AtomicLong;
import org.apache.lucene.util.ThreadInterruptedException;
/**
* A memory-resident {@link Directory} implementation. Locking
* implementation is by default the {@link SingleInstanceLockFactory}
* but can be changed with {@link #setLockFactory}.
*/
public class RAMDirectory extends Directory implements Serializable {
private static final long serialVersionUID = 1l;
HashMap<String,RAMFile> fileMap = new HashMap<String,RAMFile>();
final AtomicLong sizeInBytes = new AtomicLong();
// *****
// Lock acquisition sequence: RAMDirectory, then RAMFile
// *****
/** Constructs an empty {@link Directory}. */
public RAMDirectory() {
setLockFactory(new SingleInstanceLockFactory());
}
/**
* Creates a new <code>RAMDirectory</code> instance from a different
* <code>Directory</code> implementation. This can be used to load
* a disk-based index into memory.
* <P>
* This should be used only with indices that can fit into memory.
* <P>
* Note that the resulting <code>RAMDirectory</code> instance is fully
* independent from the original <code>Directory</code> (it is a
* complete copy). Any subsequent changes to the
* original <code>Directory</code> will not be visible in the
* <code>RAMDirectory</code> instance.
*
* @param dir a <code>Directory</code> value
* @exception IOException if an error occurs
*/
public RAMDirectory(Directory dir) throws IOException {
this(dir, false);
}
private RAMDirectory(Directory dir, boolean closeDir) throws IOException {
this();
for (String file : dir.listAll()) {
dir.copy(this, file, file);
}
if (closeDir) {
dir.close();
}
}
@Override
public synchronized final String[] listAll() {
ensureOpen();
Set<String> fileNames = fileMap.keySet();
String[] result = new String[fileNames.size()];
int i = 0;
for(final String fileName: fileNames)
result[i++] = fileName;
return result;
}
/** Returns true iff the named file exists in this directory. */
@Override
public final boolean fileExists(String name) {
ensureOpen();
RAMFile file;
synchronized (this) {
file = fileMap.get(name);
}
return file != null;
}
/** Returns the time the named file was last modified.
* @throws IOException if the file does not exist
*/
@Override
public final long fileModified(String name) throws IOException {
ensureOpen();
RAMFile file;
synchronized (this) {
file = fileMap.get(name);
}
if (file==null)
throw new FileNotFoundException(name);
return file.getLastModified();
}
/** Set the modified time of an existing file to now.
* @throws IOException if the file does not exist
*/
@Override
public void touchFile(String name) throws IOException {
ensureOpen();
RAMFile file;
synchronized (this) {
file = fileMap.get(name);
}
if (file==null)
throw new FileNotFoundException(name);
long ts2, ts1 = System.currentTimeMillis();
do {
try {
Thread.sleep(0, 1);
} catch (InterruptedException ie) {
throw new ThreadInterruptedException(ie);
}
ts2 = System.currentTimeMillis();
} while(ts1 == ts2);
file.setLastModified(ts2);
}
/** Returns the length in bytes of a file in the directory.
* @throws IOException if the file does not exist
*/
@Override
public final long fileLength(String name) throws IOException {
ensureOpen();
RAMFile file;
synchronized (this) {
file = fileMap.get(name);
}
if (file==null)
throw new FileNotFoundException(name);
return file.getLength();
}
/** Return total size in bytes of all files in this
* directory. This is currently quantized to
* RAMOutputStream.BUFFER_SIZE. */
public synchronized final long sizeInBytes() {
ensureOpen();
return sizeInBytes.get();
}
/** Removes an existing file in the directory.
* @throws IOException if the file does not exist
*/
@Override
public synchronized void deleteFile(String name) throws IOException {
ensureOpen();
RAMFile file = fileMap.get(name);
if (file!=null) {
fileMap.remove(name);
file.directory = null;
sizeInBytes.addAndGet(-file.sizeInBytes);
} else
throw new FileNotFoundException(name);
}
/** Creates a new, empty file in the directory with the given name. Returns a stream writing this file. */
@Override
public IndexOutput createOutput(String name) throws IOException {
ensureOpen();
RAMFile file = new RAMFile(this);
synchronized (this) {
RAMFile existing = fileMap.get(name);
if (existing!=null) {
sizeInBytes.addAndGet(-existing.sizeInBytes);
existing.directory = null;
}
fileMap.put(name, file);
}
return new RAMOutputStream(file);
}
/** Returns a stream reading an existing file. */
@Override
public IndexInput openInput(String name) throws IOException {
ensureOpen();
RAMFile file;
synchronized (this) {
file = fileMap.get(name);
}
if (file == null)
throw new FileNotFoundException(name);
return new RAMInputStream(file);
}
/** Closes the store to future operations, releasing associated memory. */
@Override
public void close() {
isOpen = false;
fileMap = null;
}
}