src/java/org/apache/lucene/store/RAMDirectory.java

package org.apache.lucene.store;

/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2001 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation" and
 *    "Apache Lucene" must not be used to endorse or promote products
 *    derived from this software without prior written permission. For
 *    written permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache",
 *    "Apache Lucene", nor may "Apache" appear in their name, without
 *    prior written permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

import java.io.IOException;
import java.util.Vector;
import java.util.Hashtable;
import java.util.Enumeration;

import org.apache.lucene.store.Directory;
import org.apache.lucene.store.InputStream;
import org.apache.lucene.store.OutputStream;

final public class RAMDirectory extends Directory {
  Hashtable files = new Hashtable();

  public RAMDirectory() {
  }

  /** Returns an array of strings, one for each file in the directory. */
  public final String[] list() {
    String[] result = new String[files.size()];
    int i = 0;
    Enumeration names = files.keys();
    while (names.hasMoreElements())
      result[i++] = (String)names.nextElement();
    return result;
  }
       
  /** Returns true iff the named file exists in this directory. */
  public final boolean fileExists(String name) {
    RAMFile file = (RAMFile)files.get(name);
    return file != null;
  }

  /** Returns the time the named file was last modified. */
  public final long fileModified(String name) throws IOException {
    RAMFile file = (RAMFile)files.get(name);
    return file.lastModified;
  }

  /** Returns the length in bytes of a file in the directory. */
  public final long fileLength(String name) {
    RAMFile file = (RAMFile)files.get(name);
    return file.length;
  }

  /** Removes an existing file in the directory. */
  public final void deleteFile(String name) {
    files.remove(name);
  }

  /** Removes an existing file in the directory. */
  public final void renameFile(String from, String to) {
    RAMFile file = (RAMFile)files.get(from);
    files.remove(from);
    files.put(to, file);
  }

  /** Creates a new, empty file in the directory with the given name.
      Returns a stream writing this file. */
  public final OutputStream createFile(String name) {
    RAMFile file = new RAMFile();
    files.put(name, file);
    return new RAMOutputStream(file);
  }

  /** Returns a stream reading an existing file. */
  public final InputStream openFile(String name) {
    RAMFile file = (RAMFile)files.get(name);
    return new RAMInputStream(file);
  }

  /** Construct a {@link Lock}.
   * @param name the name of the lock file
   */
  public final Lock makeLock(final String name) {
    return new Lock() {
	public boolean obtain() throws IOException {
	  synchronized (files) {
	    if (!fileExists(name)) {
	      createFile(name).close();
	      return true;
	    }
	    return false;
	  }
	}
	public void release() {
	  deleteFile(name);
	}
      };
  }

  /** Closes the store to future operations. */
  public final void close() {
  }
}


final class RAMInputStream extends InputStream implements Cloneable {
  RAMFile file;
  int pointer = 0;

  public RAMInputStream(RAMFile f) {
    file = f;
    length = file.length;
  }

  /** InputStream methods */
  public final void readInternal(byte[] dest, int destOffset, int len) {
    int bufferNumber = pointer/InputStream.BUFFER_SIZE;
    int bufferOffset = pointer%InputStream.BUFFER_SIZE;
    int bytesInBuffer = InputStream.BUFFER_SIZE - bufferOffset;
    int bytesToCopy = bytesInBuffer >= len ? len : bytesInBuffer;
    byte[] buffer = (byte[])file.buffers.elementAt(bufferNumber);
    System.arraycopy(buffer, bufferOffset, dest, destOffset, bytesToCopy);

    if (bytesToCopy < len) {			  // not all in one buffer
      destOffset += bytesToCopy;
      bytesToCopy = len - bytesToCopy;		  // remaining bytes
      buffer = (byte[])file.buffers.elementAt(bufferNumber+1);
      System.arraycopy(buffer, 0, dest, destOffset, bytesToCopy);
    }
    pointer += len;
  }
  public final void close() {
  }

  /** Random-access methods */
  public final void seekInternal(long pos) {
    pointer = (int)pos;
  }
}


final class RAMOutputStream extends OutputStream {
  RAMFile file;
  int pointer = 0;

  public RAMOutputStream(RAMFile f) {
    file = f;
  }

  /** output methods: */
  public final void flushBuffer(byte[] src, int len) {
    int bufferNumber = pointer/OutputStream.BUFFER_SIZE;
    int bufferOffset = pointer%OutputStream.BUFFER_SIZE;
    int bytesInBuffer = OutputStream.BUFFER_SIZE - bufferOffset;
    int bytesToCopy = bytesInBuffer >= len ? len : bytesInBuffer;

    if (bufferNumber == file.buffers.size())
      file.buffers.addElement(new byte[OutputStream.BUFFER_SIZE]);

    byte[] buffer = (byte[])file.buffers.elementAt(bufferNumber);
    System.arraycopy(src, 0, buffer, bufferOffset, bytesToCopy);

    if (bytesToCopy < len) {			  // not all in one buffer
      int srcOffset = bytesToCopy;
      bytesToCopy = len - bytesToCopy;		  // remaining bytes
      bufferNumber++;
      if (bufferNumber == file.buffers.size())
	file.buffers.addElement(new byte[OutputStream.BUFFER_SIZE]);
      buffer = (byte[])file.buffers.elementAt(bufferNumber);
      System.arraycopy(src, srcOffset, buffer, 0, bytesToCopy);
    }
    pointer += len;
    if (pointer > file.length)
      file.length = pointer;

    file.lastModified = System.currentTimeMillis();
  }

  public final void close() throws IOException {
    super.close();
  }

  /** Random-access methods */
  public final void seek(long pos) throws IOException {
    super.seek(pos);
    pointer = (int)pos;
  }
  public final long length() throws IOException {
    return file.length;
  }
}

final class RAMFile {
  Vector buffers = new Vector();
  long length;
  long lastModified = System.currentTimeMillis();
}