| 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.util.ArrayList; |
| import java.util.Collection; |
| import java.util.List; |
| import java.util.Map; |
| import java.util.Set; |
| import java.util.concurrent.ConcurrentHashMap; |
| import java.util.concurrent.atomic.AtomicLong; |
| |
| |
| /** |
| * A memory-resident {@link Directory} implementation. Locking |
| * implementation is by default the {@link SingleInstanceLockFactory} |
| * but can be changed with {@link #setLockFactory}. |
| * |
| * <p><b>Warning:</b> This class is not intended to work with huge |
| * indexes. Everything beyond several hundred megabytes will waste |
| * resources (GC cycles), because it uses an internal buffer size |
| * of 1024 bytes, producing millions of {@code byte[1024]} arrays. |
| * This class is optimized for small memory-resident indexes. |
| * It also has bad concurrency on multithreaded environments. |
| * |
| * <p>It is recommended to materialize large indexes on disk and use |
| * {@link MMapDirectory}, which is a high-performance directory |
| * implementation working directly on the file system cache of the |
| * operating system, so copying data to Java heap space is not useful. |
| */ |
| public class RAMDirectory extends BaseDirectory { |
| protected final Map<String,RAMFile> fileMap = new ConcurrentHashMap<>(); |
| protected final AtomicLong sizeInBytes = new AtomicLong(); |
| |
| // ***** |
| // Lock acquisition sequence: RAMDirectory, then RAMFile |
| // ***** |
| |
| /** Constructs an empty {@link Directory}. */ |
| public RAMDirectory() { |
| try { |
| setLockFactory(new SingleInstanceLockFactory()); |
| } catch (IOException e) { |
| // Cannot happen |
| } |
| } |
| |
| /** |
| * 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><b>Warning:</b> This class is not intended to work with huge |
| * indexes. Everything beyond several hundred megabytes will waste |
| * resources (GC cycles), because it uses an internal buffer size |
| * of 1024 bytes, producing millions of {@code byte[1024]} arrays. |
| * This class is optimized for small memory-resident indexes. |
| * It also has bad concurrency on multithreaded environments. |
| * |
| * <p>For disk-based indexes it is recommended to use |
| * {@link MMapDirectory}, which is a high-performance directory |
| * implementation working directly on the file system cache of the |
| * operating system, so copying data to Java heap space is not useful. |
| * |
| * <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, IOContext context) throws IOException { |
| this(dir, false, context); |
| } |
| |
| private RAMDirectory(Directory dir, boolean closeDir, IOContext context) throws IOException { |
| this(); |
| for (String file : dir.listAll()) { |
| dir.copy(this, file, file, context); |
| } |
| if (closeDir) { |
| dir.close(); |
| } |
| } |
| |
| @Override |
| public String getLockID() { |
| return "lucene-" + Integer.toHexString(hashCode()); |
| } |
| |
| @Override |
| public final String[] listAll() { |
| ensureOpen(); |
| // NOTE: fileMap.keySet().toArray(new String[0]) is broken in non Sun JDKs, |
| // and the code below is resilient to map changes during the array population. |
| Set<String> fileNames = fileMap.keySet(); |
| List<String> names = new ArrayList<>(fileNames.size()); |
| for (String name : fileNames) names.add(name); |
| return names.toArray(new String[names.size()]); |
| } |
| |
| public final boolean fileNameExists(String name) { |
| ensureOpen(); |
| return fileMap.containsKey(name); |
| } |
| |
| /** 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 = 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 final long sizeInBytes() { |
| ensureOpen(); |
| return sizeInBytes.get(); |
| } |
| |
| /** Removes an existing file in the directory. |
| * @throws IOException if the file does not exist |
| */ |
| @Override |
| public void deleteFile(String name) throws IOException { |
| ensureOpen(); |
| RAMFile file = fileMap.remove(name); |
| if (file != null) { |
| 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, IOContext context) throws IOException { |
| ensureOpen(); |
| RAMFile file = newRAMFile(); |
| RAMFile existing = fileMap.remove(name); |
| if (existing != null) { |
| sizeInBytes.addAndGet(-existing.sizeInBytes); |
| existing.directory = null; |
| } |
| fileMap.put(name, file); |
| return new RAMOutputStream(file, true); |
| } |
| |
| /** |
| * Returns a new {@link RAMFile} for storing data. This method can be |
| * overridden to return different {@link RAMFile} impls, that e.g. override |
| * {@link RAMFile#newBuffer(int)}. |
| */ |
| protected RAMFile newRAMFile() { |
| return new RAMFile(this); |
| } |
| |
| @Override |
| public void sync(Collection<String> names) throws IOException { |
| } |
| |
| /** Returns a stream reading an existing file. */ |
| @Override |
| public IndexInput openInput(String name, IOContext context) throws IOException { |
| ensureOpen(); |
| RAMFile file = fileMap.get(name); |
| if (file == null) { |
| throw new FileNotFoundException(name); |
| } |
| return new RAMInputStream(name, file); |
| } |
| |
| /** Closes the store to future operations, releasing associated memory. */ |
| @Override |
| public void close() { |
| isOpen = false; |
| fileMap.clear(); |
| } |
| |
| } |