cvs commit: jakarta-lucene/src/java/org/apache/lucene/store MMapDirectory.java

[cutting]

cutting     2004/09/28 14:40:11

  Added:       src/java/org/apache/lucene/store MMapDirectory.java
  Log:
  Add an nio mmap based Directory implementation.
  
  Revision  Changes    Path
  1.1                  
jakarta-lucene/src/java/org/apache/lucene/store/MMapDirectory.java
  
  Index: MMapDirectory.java
  ===================================================================
  package org.apache.lucene.store;
  
  /**
   * Copyright 2004 The Apache Software Foundation
   *
   * Licensed 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.File;
  import java.io.RandomAccessFile;
  import java.nio.ByteBuffer;
  import java.nio.channels.FileChannel;
  import java.nio.channels.FileChannel.MapMode;
  
  /** File-based [EMAIL PROTECTED] Directory} implementation that uses mmap for input.
   *
   * <p>To use this, invoke Java with the System property
   * org.apache.lucene.FSDirectory.class set to
   * org.apache.lucene.store.MMapDirectory.  This will cause [EMAIL PROTECTED]
   * FSDirectory#getDirectory(File,boolean)} to return instances of this class.
   *
   * @author Doug Cutting
   */
  public class MMapDirectory extends FSDirectory {
  
    private class MMapIndexInput extends IndexInput {
  
      private ByteBuffer buffer;
      private RandomAccessFile file;
      private long length;
      private boolean isClone;
  
      public MMapIndexInput(String path) throws IOException {
        this.file = new RandomAccessFile(path, "r");
        this.length = file.length();
        this.buffer = file.getChannel().map(MapMode.READ_ONLY, 0, length);
      }
  
      public byte readByte() throws IOException {
        return buffer.get();
      }
  
      public void readBytes(byte[] b, int offset, int len)
        throws IOException {
        buffer.get(b, offset, len);
      }
  
      public long getFilePointer() {
        return buffer.position();
      }
  
      public void seek(long pos) throws IOException {
        buffer.position((int)pos);
      }
  
      public long length() {
        return length;
      }
  
      public Object clone() {
        MMapIndexInput clone = (MMapIndexInput)super.clone();
        clone.isClone = true;
        clone.buffer = buffer.duplicate();
        return clone;
      }
  
      public void close() throws IOException {
        if (!isClone)
          file.close();
      }
    }
  
    private MMapDirectory() {}                      // no public ctor
  
    public IndexInput openInput(String name) throws IOException {
      return new MMapIndexInput(new File(getFile(), name).getPath());
    }
  }
  
  
  
  

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