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The Apache Cassandra Project develops a highly scalable second-generation distributed database, bringing together Dynamo's fully distributed design and Bigtable's ColumnFamily-based data model.

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/*
 * 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.cassandra.utils.concurrent;

import sun.misc.Unsafe;

import java.lang.reflect.Field;

public class Locks
{
    static final Unsafe unsafe;

    static
    {
        try
        {
            Field field = sun.misc.Unsafe.class.getDeclaredField("theUnsafe");
            field.setAccessible(true);
            unsafe = (sun.misc.Unsafe) field.get(null);
        }
        catch (Exception e)
        {
            throw new AssertionError(e);
        }
    }

    // enters the object's monitor IF UNSAFE IS PRESENT. If it isn't, this is a no-op.
    public static void monitorEnterUnsafe(Object object)
    {
        if (unsafe != null)
            unsafe.monitorEnter(object);
    }

    public static void monitorExitUnsafe(Object object)
    {
        if (unsafe != null)
            unsafe.monitorExit(object);
    }
}