History.hpp
No OneTemporary
Actions

Size

17 KB

Referenced Files

None

Subscribers

None

History.hpp
View Options

	//===-- rosa/agent/History.hpp ----------------------------------- C++ --===//
	//
	// The RoSA Framework
	//
	// Distributed under the terms and conditions of the Boost Software License 1.0.
	// See accompanying file LICENSE.
	//
	// If you did not receive a copy of the license file, see
	// http://www.boost.org/LICENSE_1_0.txt.
	//
	//===----------------------------------------------------------------------===//
	///
	/// \file rosa/agent/History.hpp
	///
	/// \author David Juhasz (david.juhasz@tuwien.ac.at)
	///
	/// \date 2017
	///
	/// \brief Definition of history functionality.
	///
	//===----------------------------------------------------------------------===//

	#ifndef ROSA_AGENT_HISTORY_HPP
	#define ROSA_AGENT_HISTORY_HPP

	#include "rosa/agent/Functionality.h"

	#include "rosa/config/config.h"

	#include "rosa/support/debug.hpp"
	#include "rosa/support/type_helper.hpp"

	#include <array>
	#include <vector>

	namespace rosa {
	namespace agent {

	/// Retention policies defining what a \c rosa::agent::History instance should
	/// do when the number of recorded entries reached its capacity.
	enum class HistoryPolicy {
	SRWF, ///< Stop Recording When Full -- no new entry is recorded when full
	FIFO, ///< First In First Out -- overwrite the earliest entry with a new one
	LIFO ///< Last In First Out -- overwrite the latest entry with a new one
	};

	template <typename T, HistoryPolicy P> class History : public Functionality {

	public:
	History(void) noexcept {}

	/// Destroys \p this object.
	virtual ~History(void) = default;

	/// Tells the retention policy applied to \p this object.
	///
	/// \return \c rosa::agent::History::P
	static constexpr HistoryPolicy policy(void) noexcept { return P; }

	/// Tells how many entries may be recorded by \c this object.
	///
	/// \note The number of entries that are actually recorded may be smaller.
	///
	/// \return The max number of entries that may be recorded
	virtual size_t maxLength(void) const noexcept = 0;

	/// Tells how many entries are currently recorded by \p this object.
	///
	/// \return number of entries currently recorded by \p this object.
	///
	/// \post The returned value cannot be larger than the capacity of \p this
	/// object:\code
	/// 0 <= numberOfEntries() && numberOfEntries <= lengthOfHistory()
	/// \endcode
	virtual size_t numberOfEntries(void) const noexcept = 0;

	/// Tells if \p this object has not recorded anything yet.
	///
	/// \return if \p this object has no entries recorded
	bool empty(void) const noexcept { return numberOfEntries() == 0; }

	/// Tells if the history reached it's maximum length
	///
	/// \return if the history reached it's maximum length.
	bool full(void) const noexcept { return numberOfEntries() == maxLength(); }

	/// Gives a constant lvalue reference to an entry stored in \p this object.
	///
	/// \note The recorded entries are indexed starting from the latest one.
	///
	/// \param I the index at which the stored entry to take from
	///
	/// \pre \p I is a valid index:\code
	/// 0 <= I && I < numberOfEntries()
	/// \endcode
	virtual const T &entry(const size_t I = 0) const noexcept = 0;

	/// Removes all entries recorded in \p this object.
	virtual void clear() noexcept = 0;

	private:
	/// Pushes a new entry into the history.
	///
	/// \note The earliest entry gets overwritten if the history is full.
	///
	/// \param V value to push into the history
	virtual void pushBack(const T &V) noexcept = 0;

	/// Replaces the most recent entry in the history.
	///
	/// \param V value to replace the most current value with
	virtual void replaceFront(const T &V) noexcept = 0;

	public:
	/// Adds a new entry to \p this object and tells if the operation was
	/// successful.
	///
	/// \note Success of the operation depends on the actual policy.
	///
	/// \param V value to store
	///
	/// \return if \p V was successfully stored
	bool addEntry(const T &V) noexcept {
	switch (P) {
	default:
	ROSA_CRITICAL("unkown HistoryPolicy");
	case HistoryPolicy::LIFO:
	if (full()) {
	replaceFront(V);
	return true;
	}
	case HistoryPolicy::SRWF:
	if (full()) {
	return false;
	}
	// \note Fall through to FIFO which unconditionally pushes the new entry.
	case HistoryPolicy::FIFO:
	// FIFO and SRWF not full.
	pushBack(V);
	return true;
	}
	}

	/// Tells the trend set by the entries recorded by \p this object.
	///
	/// The number of steps to go back when calculating the trend is defined as
	/// argument to the function.
	///
	/// \note The number of steps that can be made is limited by the number of
	/// entries recorded by \p this object.
	///
	/// \note The function is made a template only to be able to use
	/// \c std::enable_if.
	///
	/// \tparam X always use the default!
	///
	/// \param D number of steps to go back in history
	///
	/// \return trend set by analyzed entries
	///
	/// \pre Statically, \p this object stores signed arithmetic values:\code
	/// std::is_arithmetic<T>::value && std::is_signed<T>::value
	/// \endcode Dynamically, \p D is a valid number of steps to take:\code
	/// 0 <= D && D < lengthOfHistory()
	/// \endcode
	template <typename X = T>
	typename std::enable_if<
	std::is_arithmetic<X>::value && std::is_signed<X>::value, X>::type
	trend(const size_t D) const noexcept {
	STATIC_ASSERT((std::is_same<X, T>::value), "not default template arg");
	ASSERT(0 <= D && D < maxLength()); // Boundary check.
	if (numberOfEntries() < 2 \|\| D < 1) {
	// No entries for computing trend.
	return {}; // Zero element of \p T
	} else {
	// Here at least two entries.
	// \c S is the number of steps that can be done.
	const size_t S = std::min(numberOfEntries() - 1, D);
	size_t I = S;

	// Compute trend with linear regression.
	size_t SumIndices = 0;
	T SumEntries = {};
	T SumSquareEntries = {};
	T SumProduct = {};
	while (I > 0) {
	// \note Indexing for the regression starts in the past.
	const size_t Index = S - I;
	const T Entry = entry(--I);
	SumIndices += Index;
	SumEntries += Entry;
	SumSquareEntries += Entry * Entry;
	SumProduct += Entry * Index;
	}

	return (SumProduct * S - SumEntries * SumIndices) /
	(SumSquareEntries * S - SumEntries * SumEntries);
	}
	}

	/// Tells the average absolute difference between consecutive entries recorded
	/// by \p this object
	/// The number of steps to go back when calculating the average is defined as
	/// argument to the function.
	///
	/// \note The number of steps that can be made is limited by the number of
	/// entries recorded by \p this object.
	///
	/// \note The function is made a template only to be able to use
	/// \c std::enable_if.
	///
	/// \tparam X always use the default!
	///
	/// \param D number of steps to go back in history
	///
	/// \pre Statically, \p this object stores arithmetic values:\code
	/// std::is_arithmetic<T>::value
	/// \endcode Dynamically, \p D is a valid number of steps to take:\code
	/// 0 <= D && D < lengthOfHistory()
	/// \endcode
	template <typename X = T>
	typename std::enable_if<std::is_arithmetic<X>::value, size_t>::type
	averageAbsDiff(const size_t D) const noexcept {
	STATIC_ASSERT((std::is_same<X, T>::value), "not default template arg");
	ASSERT(0 <= D && D < maxLength()); // Boundary check.
	if (numberOfEntries() < 2 \|\| D < 1) {
	// No difference to average.
	return {}; // Zero element of \p T
	} else {
	// Here at least two entries.
	// \c S is the number of steps that can be done.
	const size_t S = std::min(numberOfEntries() - 1, D);

	// Sum up differences as non-negative values only, hence using an
	// unsigned variable for that.
	size_t Diffs = {}; // Init to zero.
	// Count down entry indices and sum up all the absolute differences.
	size_t I = S;
	T Last = entry(I);
	while (I > 0) {
	T Next = entry(--I);
	Diffs += Last < Next ? Next - Last : Last - Next;
	Last = Next;
	}
	// Return the average of the summed differences.
	return Diffs / S;
	}
	}

	/// Tells the average of all entries recorded by \p this object
	///
	/// \tparam R type of the result
	template <typename R> R average() const noexcept {
	R Average = 0;
	for (size_t I = 0; I < numberOfEntries(); I++) {
	Average += entry(I);
	}
	Average /= numberOfEntries();
	return Average;
	}
	};

	/// Implements history by recording and storing values.
	/// The length of the underlying std::array is static and must be set at
	/// compile-time
	///
	/// \note Not thread-safe implementation, which should not be a problem as any
	/// instance of \c rosa::agent::Functionality is an internal component of a
	/// \c rosa::Agent, which is the basic unit of concurrency.
	///
	/// \tparam T type of values to store
	/// \tparam N number of values to store at most
	/// \tparam P retention policy to follow when capacity is reached
	///
	/// \invariant The size of the underlying \c std::array is `N + 1`:\code
	/// max_size() == N + 1 && N == max_size() - 1
	/// \endcode
	template <typename T, size_t N, HistoryPolicy P>
	class StaticLengthHistory : public History<T, P>, private std::array<T, N + 1> {

	// Bring into scope inherited functions that are used.
	using std::array<T, N + 1>::max_size;
	using std::array<T, N + 1>::operator[];

	/// The index of the first data element in the circular buffer.
	size_t Data;

	/// The index of the first empty slot in the circular buffer.
	size_t Space;

	public:
	using History<T, P>::policy;
	using History<T, P>::empty;
	using History<T, P>::full;
	using History<T, P>::addEntry;
	using History<T, P>::trend;
	using History<T, P>::averageAbsDiff;

	/// Creates an instances by initializing the indices for the circular buffer.
	StaticLengthHistory(void) noexcept : Data(0), Space(0) {}

	/// Destroys \p this object.
	~StaticLengthHistory(void) override = default;

	/// Tells how many entries may be recorded by \c this object.
	///
	/// \note The number of entries that are actually recorded may be smaller.
	///
	/// \return \c rosa::agent::History::N
	size_t maxLength(void) const noexcept override { return N; }

	/// Tells how many entries are currently recorded by \p this object.
	///
	/// \return number of entries currently recorded by \p this object.
	///
	/// \post The returned value cannot be larger than the capacity of \p this
	/// object:\code
	/// 0 <= numberOfEntries() && numberOfEntries <= lengthOfHistory()
	/// \endcode
	size_t numberOfEntries(void) const noexcept override {
	return Data <= Space ? Space - Data : max_size() - Data + Space;
	}

	/// Gives a constant lvalue reference to an entry stored in \p this object.
	///
	/// \note The recorded entries are indexed starting from the latest one.
	///
	/// \param I the index at which the stored entry to take from
	///
	/// \pre \p I is a valid index:\code
	/// 0 <= I && I < numberOfEntries()
	/// \endcode
	const T &entry(const size_t I = 0) const noexcept override {
	ASSERT(0 <= I && I < numberOfEntries()); // Boundary check.
	// Position counted back from the last recorded entry.
	typename std::make_signed<const size_t>::type Pos = Space - (1 + I);
	// Actual index wrapped around to the end of the buffer if negative.
	return (*this)[Pos >= 0 ? Pos : max_size() + Pos];
	}

	/// Removes all entries recorded in \p this object.
	void clear() noexcept override {
	Data = 0;
	Space = 0;
	}

	private:
	/// Pushes a new entry into the circular buffer.
	///
	/// \note The earliest entry gets overwritten if the buffer is full.
	///
	/// \param V value to push into the buffer
	void pushBack(const T &V) noexcept override {
	// Store value to the first empty slot and step Space index.
	(*this)[Space] = V;
	Space = (Space + 1) % max_size();
	if (Data == Space) {
	// Buffer was full, step Data index.
	Data = (Data + 1) % max_size();
	}
	}

	/// Replaces the most recent entry in the history.
	///
	/// \param V value to replace the most current value with
	void replaceFront(const T &V) noexcept override {
	(*this)[(Space - 1) % max_size()] = V;
	}
	};

	/// Adds a new entry to a \c rosa::agent::History instance.
	///
	/// \note The result of \c rosa::agent::History::addEntry is ignored.
	///
	/// \tparam T type of values stored in \p H
	/// \tparam N number of values \p H is able to store
	/// \tparam P retention policy followed by \p H when capacity is reached
	///
	/// \param H to add a new entry to
	/// \param V value to add to \p H
	///
	/// \return \p H after adding \p V to it
	template <typename T, size_t N, HistoryPolicy P>
	StaticLengthHistory<T, N, P> &operator<<(StaticLengthHistory<T, N, P> &H,
	const T &V) noexcept {
	H.addEntry(V);
	return H;
	}

	/// Implements DynamicLengthHistory by recording and storing values.
	///
	/// \note Not thread-safe implementation, which should not be a problem as any
	/// instance of \c rosa::agent::Functionality is an internal component of a
	/// \c rosa::Agent, which is the basic unit of concurrency.
	///
	/// \tparam T type of values to store
	/// \tparam P retention policy to follow when capacity is reached
	template <typename T, HistoryPolicy P>
	class DynamicLengthHistory : public History<T, P>, private std::vector<T> {

	// Bring into scope inherited functions that are used.
	using std::vector<T>::erase;
	using std::vector<T>::begin;
	using std::vector<T>::end;
	using std::vector<T>::size;
	using std::vector<T>::max_size;
	using std::vector<T>::resize;
	using std::vector<T>::push_back;
	using std::vector<T>::pop_back;
	using std::vector<T>::operator[];

	/// The current length of the DynamicLengthHistory.
	size_t Length;

	public:
	using History<T, P>::policy;
	using History<T, P>::empty;
	using History<T, P>::full;
	using History<T, P>::addEntry;
	using History<T, P>::trend;
	using History<T, P>::averageAbsDiff;

	/// Creates an instances by setting an initial length
	DynamicLengthHistory(size_t Length) noexcept : Length(Length) {
	this->resize(Length);
	}

	/// Destroys \p this object.
	~DynamicLengthHistory(void) override = default;

	/// Tells how many entries may be recorded by \c this object.
	///
	/// \note The number of entries that are actually recorded may be smaller.
	///
	/// \return \c rosa::agent::DynamicLengthHistory::N
	size_t maxLength(void) const noexcept override { return Length; }

	/// Tells how many entries are currently recorded by \p this object.
	///
	/// \return number of entries currently recorded by \p this object.
	///
	/// \post The returned value cannot be larger than the capacity of \p this
	/// object:\code
	/// 0 <= numberOfEntries() && numberOfEntries <=
	/// lengthOfHistory() \endcode
	size_t numberOfEntries(void) const noexcept { return size(); }

	/// Gives a constant lvalue reference to an entry stored in \p this object.
	///
	/// \note The recorded entries are indexed starting from the latest one.
	///
	/// \param I the index at which the stored entry to take from
	///
	/// \pre \p I is a valid index:\code
	/// 0 <= I && I < numberOfEntries()
	/// \endcode
	const T &entry(const size_t I = 0) const noexcept override {
	ASSERT(0 <= I && I < numberOfEntries()); // Boundary check.
	return this->operator[](size() - I - 1);
	}

	/// Removes all entries recorded in \p this object.
	void clear() noexcept override { erase(begin(), end()); }

	private:
	/// Pushes a new entry into the circular buffer.
	///
	/// \note The earliest entry gets overwritten if the buffer is full.
	///
	/// \param V value to push into the buffer
	void pushBack(const T &V) noexcept override {
	if (full()) {
	erase(begin());
	}
	push_back(V);
	}

	/// Replaces the most recent entry in the history.
	///
	/// \param V value to replace the most current value with
	void replaceFront(const T &V) noexcept override {
	(void)pop_back();
	push_back(V);
	}

	public:
	/// Resizes the History length. If the new length is smaller than the number
	/// of currently stored values, values are deleted according to the
	/// HistoryPolicy.
	///
	/// @param NewLength The new Length of the History.
	void setLength(size_t NewLength) noexcept {
	Length = NewLength;
	if (NewLength < numberOfEntries()) {
	switch (P) {
	default:
	ROSA_CRITICAL("unkown HistoryPolicy");
	case HistoryPolicy::LIFO:
	case HistoryPolicy::SRWF:
	// Delete last numberOfEntries() - NewLength items from the back
	erase(begin() + NewLength, end());
	break;
	case HistoryPolicy::FIFO:
	// Delete last numberOfEntries() - NewLength items from the front
	erase(begin(), begin() + (numberOfEntries() - NewLength));
	break;
	}
	}
	this->resize(Length);
	}
	};

	/// Adds a new entry to a \c rosa::agent::DynamicLengthHistory instance.
	///
	/// \note The result of \c rosa::agent::DynamicLengthHistory::addEntry is
	/// ignored.
	///
	/// \tparam T type of values stored in \p H
	/// \tparam P retention policy followed by \p H when capacity is reached
	///
	/// \param H to add a new entry to
	/// \param V value to add to \p H
	///
	/// \return \p H after adding \p V to it
	template <typename T, HistoryPolicy P>
	DynamicLengthHistory<T, P> &operator<<(DynamicLengthHistory<T, P> &H,
	const T &V) noexcept {
	H.addEntry(V);
	return H;
	}
	} // End namespace agent
	} // End namespace rosa

	#endif // ROSA_AGENT_HISTORY_HPP

File Metadata

Mime Type: text/x-c++
Expires: Sun, Jun 8, 2:15 AM (1 d, 4 h)
Storage Engine: blob
Storage Format: Raw Data
Storage Handle: 150329
Default Alt Text: History.hpp (17 KB)

History.hppNo OneTemporaryActions

History.hppView Options

File Metadata

Event Timeline

History.hpp
No OneTemporary
Actions

History.hpp
View Options