MMFUtil.java

package com.ctriposs.sdb.utils;

import java.lang.reflect.Method;
import java.nio.ByteBuffer;
import java.nio.MappedByteBuffer;

/**
 * Memory mapped file util
 * 
 * @author bulldog
 *
 */
public class MMFUtil {
	
	public static void unmap(MappedByteBuffer buffer)
	{
		Cleaner.clean(buffer);
	}
	
    /**
     * Helper class allowing to clean direct buffers.
     */
    private static class Cleaner {
        public static final boolean CLEAN_SUPPORTED;
        private static final Method directBufferCleaner;
        private static final Method directBufferCleanerClean;

        static {
            Method directBufferCleanerX = null;
            Method directBufferCleanerCleanX = null;
            boolean v;
            try {
                directBufferCleanerX = Class.forName("java.nio.DirectByteBuffer").getMethod("cleaner");
                directBufferCleanerX.setAccessible(true);
                directBufferCleanerCleanX = Class.forName("sun.misc.Cleaner").getMethod("clean");
                directBufferCleanerCleanX.setAccessible(true);
                v = true;
            } catch (Exception e) {
                v = false;
            }
            CLEAN_SUPPORTED = v;
            directBufferCleaner = directBufferCleanerX;
            directBufferCleanerClean = directBufferCleanerCleanX;
        }

        public static void clean(ByteBuffer buffer) {
    		if (buffer == null) return;
            if (CLEAN_SUPPORTED && buffer.isDirect()) {
                try {
                    Object cleaner = directBufferCleaner.invoke(buffer);
                    directBufferCleanerClean.invoke(cleaner);
                } catch (Exception e) {
                    // silently ignore exception
                }
            }
        }
    }

}