////////////////////////////////////////////////////////////////////////////////
/// DISCLAIMER
///
/// Copyright 2014-2016 ArangoDB GmbH, Cologne, Germany
/// Copyright 2004-2014 triAGENS GmbH, Cologne, Germany
///
/// 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.
///
/// Copyright holder is ArangoDB GmbH, Cologne, Germany
///
/// @author Jan Steemann
////////////////////////////////////////////////////////////////////////////////

#ifndef ARANGOD_MMFILES_MMFILES_REVISIONS_CACHE_H
#define ARANGOD_MMFILES_MMFILES_REVISIONS_CACHE_H 1

#include "Basics/AssocUnique.h"
#include "Basics/Common.h"
#include "Basics/ReadWriteLock.h"
#include "Basics/fasthash.h"
#include "MMFiles/MMFilesDocumentPosition.h"
#include "VocBase/LocalDocumentId.h"
#include "VocBase/voc-types.h"

struct MMFilesMarker;

namespace arangodb {

struct MMFilesRevisionsCacheHelper {
  static inline uint64_t HashKey(LocalDocumentId::BaseType const* key) {
    return fasthash64_uint64(*key, 0xdeadbeef);
  }

  static inline uint64_t HashElement(MMFilesDocumentPosition const& element, bool) {
    return fasthash64_uint64(element.localDocumentIdValue(), 0xdeadbeef);
  }

  inline bool IsEqualKeyElement(void*, LocalDocumentId::BaseType const* key,
                                MMFilesDocumentPosition const& element) const {
    return *key == element.localDocumentIdValue();
  }

  inline bool IsEqualElementElement(void*, MMFilesDocumentPosition const& left,
                                    MMFilesDocumentPosition const& right) const {
    return left.localDocumentIdValue() == right.localDocumentIdValue();
  }

  inline bool IsEqualElementElementByKey(void*, MMFilesDocumentPosition const& left,
                                         MMFilesDocumentPosition const& right) const {
    return IsEqualElementElement(nullptr, left, right);
  }
};

class MMFilesRevisionsCache {
 public:
  MMFilesRevisionsCache();
  ~MMFilesRevisionsCache();

 public:
  void sizeHint(int64_t hint);
  size_t size();
  size_t capacity();
  size_t memoryUsage();
  void clear();
  MMFilesDocumentPosition lookup(LocalDocumentId const& documentId) const;
  MMFilesDocumentPosition insert(LocalDocumentId const& documentId, uint8_t const* dataptr,
                                 TRI_voc_fid_t fid, bool isInWal, bool shouldLock);
  void batchLookup(std::vector<std::pair<LocalDocumentId, uint8_t const*>>& documentIds) const;
  void insert(MMFilesDocumentPosition const& position, bool shouldLock);
  void update(LocalDocumentId const& documentId, uint8_t const* dataptr,
              TRI_voc_fid_t fid, bool isInWal);
  bool updateConditional(LocalDocumentId const& documentId,
                         MMFilesMarker const* oldPosition, MMFilesMarker const* newPosition,
                         TRI_voc_fid_t newFid, bool isInWal);
  void remove(LocalDocumentId const& documentId);
  MMFilesDocumentPosition fetchAndRemove(LocalDocumentId const& documentId);

 private:
  mutable arangodb::basics::ReadWriteLock _lock;

  arangodb::basics::AssocUnique<LocalDocumentId::BaseType, MMFilesDocumentPosition, MMFilesRevisionsCacheHelper> _positions;
};

}  // namespace arangodb

#endif