drain.hh

Go to the documentation of this file.

/*
 * Copyright (c) 2012, 2015, 2017 ARM Limited
 * All rights reserved
 *
 * The license below extends only to copyright in the software and shall
 * not be construed as granting a license to any other intellectual
 * property including but not limited to intellectual property relating
 * to a hardware implementation of the functionality of the software
 * licensed hereunder.  You may use the software subject to the license
 * terms below provided that you ensure that this notice is replicated
 * unmodified and in its entirety in all distributions of the software,
 * modified or unmodified, in source code or in binary form.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met: redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer;
 * redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution;
 * neither the name of the copyright holders nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Authors: Andreas Sandberg
 */

#ifndef __SIM_DRAIN_HH__
#define __SIM_DRAIN_HH__

#include <atomic>
#include <mutex>
#include <vector>

class Drainable;

enum class DrainState {
    Running,  
    Draining, 
    Drained,  
    Resuming, 
};

class DrainManager
{
  private:
    DrainManager();
    DrainManager(DrainManager &) = delete;
    ~DrainManager();

  public:
    static DrainManager &instance() { return _instance; }

    bool tryDrain();

    void resume();

    void preCheckpointRestore();

    bool isDrained() const { return _state == DrainState::Drained; }

    DrainState state() const { return _state; }

    void signalDrainDone();

  public:
    void registerDrainable(Drainable *obj);
    void unregisterDrainable(Drainable *obj);

  private:
    bool allInState(DrainState state) const;

    size_t drainableCount() const;

    mutable std::mutex globalLock;

    std::vector<Drainable *> _allDrainable;

    std::atomic_uint _count;

    DrainState _state;

    static DrainManager _instance;
};

class Drainable
{
    friend class DrainManager;

  protected:
    Drainable();
    virtual ~Drainable();

    virtual DrainState drain() = 0;

    virtual void drainResume() {};

    void signalDrainDone() const {
        switch (_drainState) {
          case DrainState::Running:
          case DrainState::Drained:
          case DrainState::Resuming:
            return;
          case DrainState::Draining:
            _drainState = DrainState::Drained;
            _drainManager.signalDrainDone();
            return;
        }
    }

  public:
    DrainState drainState() const { return _drainState; }

    virtual void notifyFork() {};

  private:
    DrainState dmDrain();
    void dmDrainResume();

    DrainManager &_drainManager;

    mutable DrainState _drainState;
};

#endif