rocksdb/util/memory_usage.h

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// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same directory.
#pragma once
#include <unordered_map>
namespace rocksdb {
// 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) {
typedef std::unordered_map<Key, Value, Hash> Map;
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*);
}
} // namespace rocksdb