lucene/misc/src/java/org/apache/lucene/store/NativePosixUtil.java

/*
 * 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.
 */
package org.apache.lucene.store;

import java.io.IOException;
import java.io.FileDescriptor;
import java.nio.ByteBuffer;

/**
 * Provides JNI access to native methods such as madvise() for
 * {@link NativeUnixDirectory}
 */
public final class NativePosixUtil {
  public final static int NORMAL = 0;
  public final static int SEQUENTIAL = 1;
  public final static int RANDOM = 2;
  public final static int WILLNEED = 3;
  public final static int DONTNEED = 4;
  public final static int NOREUSE = 5;

  static {
    System.loadLibrary("NativePosixUtil");
  }

  private static native int posix_fadvise(FileDescriptor fd, long offset, long len, int advise) throws IOException;
  public static native int posix_madvise(ByteBuffer buf, int advise) throws IOException;
  public static native int madvise(ByteBuffer buf, int advise) throws IOException;
  public static native FileDescriptor open_direct(String filename, boolean read) throws IOException;
  public static native long pread(FileDescriptor fd, long pos, ByteBuffer byteBuf) throws IOException;

  public static void advise(FileDescriptor fd, long offset, long len, int advise) throws IOException {
    final int code = posix_fadvise(fd, offset, len, advise);
    if (code != 0) {
      throw new RuntimeException("posix_fadvise failed code=" + code);
    }
  }
}