SensorBase.h

/*
 * SensorBase.h
 *
 *  Created on: 09.08.2018
 *      Author: Micha Mueller
 */

#ifndef SRC_SENSORBASE_H_
#define SRC_SENSORBASE_H_

#include <fstream>
#include <memory>
#include <string>
#include <limits.h>
#include <boost/lockfree/spsc_queue.hpp>

typedef struct {
	int64_t  value;
	uint64_t timestamp;
} reading_t;

class SensorBase {
public:
	static const size_t QUEUE_MAXLIMIT=1024;

	SensorBase(const std::string& name) :
			_name(name),
			_mqtt(""),
			_sinkPath(""),
			_skipConstVal(false),
			_cacheInterval(900000),
			_subsamplingFactor(1),
			_subsamplingIndex(0),
			_cacheSize(1),
			_cacheIndex(0),
			_cache(nullptr),
			_delta(false),
			_firstReading(true),
			_readingQueue(nullptr),
			_sinkFile(nullptr) {

		_latestValue.timestamp	= 0;
		_latestValue.value		= 0;
		_lastSentValue.timestamp= 0;
		_lastSentValue.value	= 0;
		_lastRawValue.timestamp = 0;
		_lastRawValue.value		= 0;
		_accumulator.timestamp  = 0;
		_accumulator.value		= 0;
	}

	SensorBase(const SensorBase& other) :
			_name(other._name),
			_mqtt(other._mqtt),
			_skipConstVal(other._skipConstVal),
			_cacheInterval(other._cacheInterval),
			_subsamplingFactor(other._subsamplingFactor),
			_subsamplingIndex(0),
			_cacheSize(other._cacheSize),
			_cacheIndex(0),
			_cache(nullptr),
			_delta(other._delta),
			_firstReading(true),
			_latestValue(other._latestValue),
			_lastRawValue(other._lastRawValue),
			_lastSentValue(other._lastSentValue),
			_accumulator(other._accumulator),
			_readingQueue(nullptr),
			_sinkFile(nullptr) {}

	virtual ~SensorBase() {}

	SensorBase& operator=(const SensorBase& other) {
		_name = other._name;
		_mqtt = other._mqtt;
		_skipConstVal = other._skipConstVal;
		_cacheInterval = other._cacheInterval;
		_subsamplingFactor = other._subsamplingFactor;
		_subsamplingIndex = 0;
		_cacheSize = other._cacheSize;
		_cacheIndex = 0;
		_cache.reset(nullptr);
		_delta = other._delta;
		_firstReading = true;
		_latestValue.timestamp	= other._latestValue.timestamp;
		_latestValue.value		= other._latestValue.value;
		_lastRawValue.timestamp = other._lastRawValue.timestamp;
		_lastRawValue.value		= other._lastRawValue.value;
		_lastSentValue.timestamp= other._lastSentValue.timestamp;
		_lastSentValue.value	= other._lastSentValue.value;
		_accumulator.timestamp  = other._accumulator.timestamp;
		_accumulator.value      = other._accumulator.value;
		_readingQueue.reset(nullptr);
		_sinkFile.reset(nullptr);

		return *this;
	}

	const bool 				isDelta()			const 	{ return _delta;}
	const std::string& 		getName() 			const	{ return _name; }
	const std::string&		getMqtt() 			const	{ return _mqtt; }
	const std::string&		getSinkPath() 		const	{ return _sinkPath; }
	bool					getSkipConstVal()	const	{ return _skipConstVal; }
	unsigned				getCacheSize()		const	{ return _cacheSize; }
	unsigned 				getSubsampling()	const   { return _subsamplingFactor; }
	const reading_t * const	getCache() 			const	{ return _cache.get(); }
	const reading_t&		getLatestValue()	const	{ return _latestValue; }

	void	setSkipConstVal(bool skipConstVal)				{ _skipConstVal = skipConstVal;	}
	void	setDelta(const bool delta) 						{ _delta = delta; }
	void	setName(const std::string& name, int cpuID=-1)	{ _name = formatName(name, cpuID); }
	void	setMqtt(const std::string& mqtt)				{ _mqtt = mqtt; }
	void 	setSinkPath(const std::string& path)			{ _sinkPath = path; }
	void 	setCacheInterval(unsigned cacheInterval)		{ _cacheInterval = cacheInterval; }
	void	setSubsampling(unsigned factor)					{ _subsamplingFactor = factor; }

	const std::size_t	getSizeOfReadingQueue() const { return _readingQueue->read_available(); }
	std::size_t 		popReadingQueue(reading_t *reads, std::size_t max) const	{ return _readingQueue->pop(reads, max); }
	void				pushReadingQueue(reading_t *reads, std::size_t count) const	{ _readingQueue->push(reads, count); }

	void initSensor(unsigned interval) {
		_cacheSize = _cacheInterval / interval + 1;
		if(!_cache) {
			_cache.reset(new reading_t[_cacheSize]);
			for(unsigned i = 0; i < _cacheSize; i++) {
				_cache[i] = _latestValue;	//_latestValue should equal (0,0) at this point
			}
		}
		if(!_readingQueue) {
			_readingQueue.reset(new boost::lockfree::spsc_queue<reading_t>(QUEUE_MAXLIMIT));
		}
		if(!_sinkFile && _sinkPath != "") {
			_sinkFile.reset(new std::ofstream(_sinkPath));
			if(!_sinkFile->is_open())
				_sinkFile.reset(nullptr);
		}
	}

	void storeReading(reading_t rawReading, double factor=1.0, unsigned long long maxValue=ULLONG_MAX) {
		reading_t reading = rawReading;
		if( _delta ) {
			if (!_firstReading) {
				if (rawReading.value < _lastRawValue.value)
					reading.value = (rawReading.value + (maxValue - _lastRawValue.value)) * factor;
				else
					reading.value = (rawReading.value - _lastRawValue.value) * factor;
			} else {
				_firstReading = false;
				_lastRawValue = rawReading;
				return;
			}
			_lastRawValue = rawReading;
		}
		else
			reading.value = rawReading.value * factor;

		if( _delta )
			// If in delta mode, _accumulator acts as a buffer, summing all deltas for the subsampling period
			_accumulator.value += reading.value;
		else
			_accumulator.value = reading.value;

		if (_subsamplingIndex++ % _subsamplingFactor == 0) {
			_accumulator.timestamp = reading.timestamp;
			//TODO: if sensor starts with values of 0, these won't be pushed. This should be fixed
			if( !(_skipConstVal && (_accumulator.value == _lastSentValue.value)) ) {
				_readingQueue->push(_accumulator);
				_lastSentValue = _accumulator;
			}
			// We reset the accumulator's value for the correct accumulation of deltas
			_accumulator.value = 0;
		}
		if (_sinkFile) {
			try {
				_sinkFile->seekp(0, std::ios::beg);
				*_sinkFile << reading.value << std::endl;
			} catch(const std::exception &e) { _sinkFile->close(); _sinkFile.reset(nullptr); }
		}

		_cache[_cacheIndex] = reading;
		_cacheIndex = (_cacheIndex + 1) % _cacheSize;
		_latestValue = reading;
	}

	int64_t getCacheOffset(int64_t t) {
		if( t < 0)
			return -1;
		// Converting from milliseconds to nanoseconds
		int64_t offset = ( ( _cacheSize * t ) / (_cacheInterval * 1000000 ) ) + 1;
		if(offset > _cacheSize)
			return -1;
		return ( _cacheSize + _cacheIndex - offset ) % _cacheSize;
	}

	static std::string formatName(const std::string& name, int cpuID=-1) {return cpuID<0 ? name : "cpu" + std::to_string(cpuID) + "." + name;}

protected:

	std::string _name;
	std::string _mqtt;
	std::string _sinkPath;
	bool _skipConstVal;
	unsigned int _cacheInterval;
	unsigned int _subsamplingFactor;
	unsigned int _subsamplingIndex;
	unsigned int _cacheSize;
	unsigned int _cacheIndex;
	std::unique_ptr<reading_t[]> _cache;
	bool _delta;
	bool _firstReading;
	reading_t _latestValue;
	reading_t _lastRawValue;
	reading_t _lastSentValue;
	reading_t _accumulator;
	std::unique_ptr<boost::lockfree::spsc_queue<reading_t>> _readingQueue;
	std::unique_ptr<std::ofstream> _sinkFile;
};

//for better readability
using SBasePtr = std::shared_ptr<SensorBase>;

#endif /* SRC_SENSORBASE_H_ */