yoko-core/src/main/java/org/apache/yoko/orb/OB/RecursiveMutex.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.yoko.orb.OB;

public class RecursiveMutex {
    private Thread owner_;

    private boolean locked_;

    private int count_;

    public RecursiveMutex() {
        owner_ = null;
        locked_ = false;
        count_ = 0;
    }

    public synchronized void lock() {
        if (locked_ && Thread.currentThread() == owner_) {
            count_++;
            return;
        }

        while (locked_) {
            try {
                wait();
            } catch (InterruptedException ex) {
            }
        }

        //
        // Assert: owner_ == null, count_ = 0
        //
        locked_ = true;
        owner_ = Thread.currentThread();
        count_ = 1;
    }

    public synchronized void unlock() {
        // Assert: owner_ == Thread.currentThread, count_ > 0, locked = true
        count_--;
        if (count_ <= 0) {
            locked_ = false;
            owner_ = null;
            notifyAll();
        }
    }
}