rocksdb/memory/memory_usage.h
Peter Dillinger 4750421ece Replace most typedef with using= (#8751)
Summary:
Old typedef syntax is confusing

Most but not all changes with

    perl -pi -e 's/typedef (.*) ([a-zA-Z0-9_]+);/using $2 = $1;/g' list_of_files
    make format

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8751

Test Plan: existing

Reviewed By: zhichao-cao

Differential Revision: D30745277

Pulled By: pdillinger

fbshipit-source-id: 6f65f0631c3563382d43347896020413cc2366d9
2021-09-07 11:31:59 -07:00

26 lines
864 B
C++

// 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 <unordered_map>
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*);
}
} // namespace ROCKSDB_NAMESPACE