//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.

//  This source code is licensed under both the GPLv2 (found in the

//  COPYING file in the root directory) and Apache 2.0 License

//  (found in the LICENSE.Apache file in the root directory).

#pragma once

#include <cstddef>

#include <unordered_map>

#ifdef USE_FOLLY

#include <folly/container/F14Map.h>

#endif

#include "rocksdb/rocksdb_namespace.h"

namespace ROCKSDB_NAMESPACE {

// Helper methods to estimate memroy usage by std containers.

template <class Key, class Value, class Hash>

size_t ApproximateMemoryUsage(

    const std::unordered_map<Key, Value, Hash>& umap) {

  using Map = std::unordered_map<Key, Value, Hash>;

  return sizeof(umap) +

         // Size of all items plus a next pointer for each item.

         (sizeof(typename Map::value_type) + sizeof(void*)) * umap.size() +

         // Size of hash buckets.

         umap.bucket_count() * sizeof(void*);

}

#ifdef USE_FOLLY

template <class Key, class Value, class Hash>

size_t ApproximateMemoryUsage(const folly::F14FastMap<Key, Value, Hash>& umap) {

  return sizeof(umap) + umap.getAllocatedMemorySize();

}

#endif

}  // namespace ROCKSDB_NAMESPACE