rocksdb/memory/memory_usage.h
sdong fdf882ded2 Replace namespace name "rocksdb" with ROCKSDB_NAMESPACE (#6433)
Summary:
When dynamically linking two binaries together, different builds of RocksDB from two sources might cause errors. To provide a tool for user to solve the problem, the RocksDB namespace is changed to a flag which can be overridden in build time.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6433

Test Plan: Build release, all and jtest. Try to build with ROCKSDB_NAMESPACE with another flag.

Differential Revision: D19977691

fbshipit-source-id: aa7f2d0972e1c31d75339ac48478f34f6cfcfb3e
2020-02-20 12:09:57 -08:00

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) {
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_NAMESPACE