Clock.h

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/*
 Copyright (2016) Michael Baer, Daniel Bonrath, All rights reserved.

 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.
 */

#ifndef __M2ETIS_UTIL_CLOCK_H__
#define __M2ETIS_UTIL_CLOCK_H__

#include <climits>
#include <map>

#include "m2etis/util/Logger.h"

#include "boost/thread.hpp"

namespace m2etis {
namespace util {

        template<class Updater>
        class Clock : public Updater {
        public:
                Clock() : Updater(boost::bind(&Clock::Update, this)), timer_(), lock_(), usedIds_(0), systemTime_(0), running_(true), offset_(0) {
                        Updater::Init();
                }

                ~Clock() {
                        Updater::Stop();
                        running_ = false;
                        boost::mutex::scoped_lock l(lock_);
                        for (std::map<uint64_t, std::pair<uint64_t, boost::condition_variable *>>::iterator it = timer_.begin(); it != timer_.end(); ++it) {
                                it->second.second->notify_all();
                                // FIXME: but there musn't be any remaing waiting processes...
                                delete it->second.second;
                        }
                        timer_.clear();
                }

                uint64_t getTime() const {
                        return systemTime_ + offset_;
                }

                uint64_t getRealTime() const {
                        return systemTime_;
                }

                uint64_t registerTimer() {
                        std::pair<uint64_t, boost::condition_variable *> p(std::make_pair(UINT64_MAX, new boost::condition_variable()));

                        boost::mutex::scoped_lock lock(lock_);
                        uint64_t id = usedIds_++;
                        timer_[id] = p;

                        return id;
                }

                void unregisterTimer(uint64_t timerID) {
                        boost::mutex::scoped_lock lock(lock_);
                        delete timer_[timerID].second;
                        timer_.erase(timerID);
                }

                void updateWaitTime(uint64_t timerID, uint64_t time) {
                        boost::mutex::scoped_lock lock(lock_);
                        if (time <= systemTime_ + offset_) {
                                timer_[timerID].second->notify_all();
                                return;
                        }
                        timer_[timerID].first = time;
                }

                bool waitForTime(uint64_t timerID, uint64_t time) {
                        if (!running_) {
                                return false;
                        }
                        boost::mutex::scoped_lock lock(lock_); // Is a scoped lock
                        if (time <= systemTime_ + offset_) {
                                return true;
                        }
                        timer_[timerID].first = time;
                        timer_[timerID].second->wait(lock);
                        return running_;
                }

                bool isRunning() {
                        return running_;
                }

                void setOffset(uint64_t offset) {
                        offset_ = offset;
                }

        private:
                //        id            wakeuptime      variable
                std::map<uint64_t, std::pair<uint64_t, boost::condition_variable *>> timer_;

                boost::mutex lock_;
                uint64_t usedIds_;

                // last system time
                volatile uint64_t systemTime_;

                volatile bool running_;

                volatile uint64_t offset_;

                void Update() {
                        if (!running_) {
                                return;
                        }
                        // Get current time.
                        boost::mutex::scoped_lock sl(lock_);
                        systemTime_ = Updater::getCurrentTime(systemTime_);
                        notifyTimer();
                }

                void notifyTimer() {
                        for (std::map<uint64_t, std::pair<uint64_t, boost::condition_variable *>>::iterator it = timer_.begin(); it != timer_.end(); ++it) {
                                if (systemTime_ + offset_ >= it->second.first) {
                                        it->second.first = UINT64_MAX;
                                        it->second.second->notify_all();
                                }
                        }
                }

                Clock(const Clock &) = delete;
                Clock & operator=(const Clock &) = delete;
        };

} /* namespace util */
} /* namespace m2etis */

#endif /* __M2ETIS_UTIL_CLOCK_H__ */