ceph/src/rocksdb/util/memory_usage.h

   1 //  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
   2 //  This source code is licensed under the BSD-style license found in the
   3 //  LICENSE file in the root directory of this source tree. An additional grant
   4 //  of patent rights can be found in the PATENTS file in the same directory.
   5
   6 #pragma once
   7
   8 #include <unordered_map>
   9
  10 namespace rocksdb {
  11
  12 // Helper methods to estimate memroy usage by std containers.
  13
  14 template <class Key, class Value, class Hash>
  15 size_t ApproximateMemoryUsage(
  16     const std::unordered_map<Key, Value, Hash>& umap) {
  17   typedef std::unordered_map<Key, Value, Hash> Map;
  18   return sizeof(umap) +
  19          // Size of all items plus a next pointer for each item.
  20          (sizeof(typename Map::value_type) + sizeof(void*)) * umap.size() +
  21          // Size of hash buckets.
  22          umap.bucket_count() * sizeof(void*);
  23 }
  24
  25 }  // namespace rocksdb