// Copyright CERN and copyright holders of ALICE O2. This software is

// distributed under the terms of the GNU General Public License v3 (GPL

// Version 3), copied verbatim in the file "COPYING".

//

// See http://alice-o2.web.cern.ch/license for full licensing information.

//

// In applying this license CERN does not waive the privileges and immunities

// granted to it by virtue of its status as an Intergovernmental Organization

// or submit itself to any jurisdiction.

#ifndef ALICEO2_MERGERCACHE_H

#define ALICEO2_MERGERCACHE_H

/// \file MergerCache.h

/// \brief Definition of O2 Merger cache, v0.1

///

/// \author Piotr Konopka, piotr.jan.konopka@cern.ch

#include <Framework/InputRecord.h>

#include <TObject.h>

#include <memory>

#include <vector>

#include <deque>

namespace o2

{

namespace experimental::mergers

{

/// \brief Merger cache to store input objects before merging them.

class MergerCache

{

/// \brief Cache entry storing one mergable object.

struct CacheEntry {

std::unique_ptr<TObject, void (*)(TObject*)> obj;

bool is_merged = false;

};

/// \biref Cache entry queue storing multiple mergable objects received at one input.

struct CacheEntryQueue {

std::deque<CacheEntry> deque;

bool was_updated = false;

};

public:

/// \brief Default constructor. When overwrite == true, only one object per input is stored.

MergerCache(bool overwrite = true);

/// \brief Default destructor.

~MergerCache() = default;

/// \brief Stores input objects from InputRecord into the cache

void cacheInputRecord(const framework::InputRecord& inputs);

size_t size();

void clear();

bool uninitialized();

const CacheEntryQueue& operator[](size_t i) const;

using const_iterator = std::vector<CacheEntryQueue>::const_iterator;

const_iterator begin() const { return mCache.begin(); }

const_iterator end() const { return mCache.end(); }

void setMerged(size_t i, size_t entry, bool merged = true);

void setAllMerged(bool merged = true);

void setUpdated(size_t i, bool updated = true);

void setAllUpdated(bool updated = true);

// returns the number of inputs that have been updated since the last time the flag was cleared (last publication)

size_t updatedInputs();

// returns the number of inputs that have some corresponding objects cached

size_t cachedInputs();

private:

/// \brief Initializes the cache by seeing the size and contents of DPL's InputRecord

void init(const framework::InputRecord& inputs);

static void deleteTCollections(TObject* obj);

std::vector<CacheEntryQueue> mCache;

// when active, cache keeps only one entry per queue (per input)

bool mOverwrite;

// keeps the index of the timer in the InputRecord

int mTimerPosition{-1};

// counts how many inputs have some corresponding objects cached

size_t mCachedInputs{0};

// counts how many inputs have been updated since the last time the flag was cleared (last publication)

size_t mUpdatedInputs{0};

};

} // namespace experimental::mergers

} // namespace o2

#endif //ALICEO2_MERGERCACHE_H