/*
 * Copyright (C) 2012 The Android Open Source Project
 *
 * 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.
 */

/*
 *  Synchronize two or more threads using a condition variable and a mutex.
 */
#pragma once
#include <mutex>

#include "CondVar.h"

class SyncEvent {
  public:
    /*******************************************************************************
    **
    ** Function:        ~SyncEvent
    **
    ** Description:     Cleanup all resources.
    **
    ** Returns:         None.
    **
    *******************************************************************************/
    ~SyncEvent() {}

    /*******************************************************************************
    **
    ** Function:        start
    **
    ** Description:     Start a synchronization operation.
    **
    ** Returns:         None.
    **
    *******************************************************************************/
    void start() { mMutex.lock(); }

    /*******************************************************************************
    **
    ** Function:        wait
    **
    ** Description:     Block the thread and wait for the event to occur.
    **
    ** Returns:         None.
    **
    *******************************************************************************/
    void wait() { mCondVar.wait(mMutex); }

    /*******************************************************************************
    **
    ** Function:        wait
    **
    ** Description:     Block the thread and wait for the event to occur.
    **                  millisec: Timeout in milliseconds.
    **
    ** Returns:         True if wait is successful; false if timeout occurs.
    **
    *******************************************************************************/
    bool wait(long millisec) {
        bool retVal = mCondVar.wait(mMutex, millisec);
        return retVal;
    }

    /*******************************************************************************
    **
    ** Function:        notifyOne
    **
    ** Description:     Notify a blocked thread that the event has occurred.
    *Unblocks it.
    **
    ** Returns:         None.
    **
    *******************************************************************************/
    void notifyOne() { mCondVar.notifyOne(); }

    /*******************************************************************************
    **
    ** Function:        end
    **
    ** Description:     End a synchronization operation.
    **
    ** Returns:         None.
    **
    *******************************************************************************/
    void end() { mMutex.unlock(); }

  private:
    CondVar mCondVar;
    std::mutex mMutex;
};

/*****************************************************************************/
/*****************************************************************************/

/*****************************************************************************
**
**  Name:           SyncEventGuard
**
**  Description:    Automatically start and end a synchronization event.
**
*****************************************************************************/
class SyncEventGuard {
  public:
    /*******************************************************************************
    **
    ** Function:        SyncEventGuard
    **
    ** Description:     Start a synchronization operation.
    **
    ** Returns:         None.
    **
    *******************************************************************************/
    SyncEventGuard(SyncEvent& event) : mEvent(event) {
        event.start();  // automatically start operation
    };

    /*******************************************************************************
    **
    ** Function:        ~SyncEventGuard
    **
    ** Description:     End a synchronization operation.
    **
    ** Returns:         None.
    **
    *******************************************************************************/
    ~SyncEventGuard() {
        mEvent.end();  // automatically end operation
    };

  private:
    SyncEvent& mEvent;
};