ceph/src/rocksdb/memory/memory_usage.h

   1 //  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
   2 //  This source code is licensed under both the GPLv2 (found in the
   3 //  COPYING file in the root directory) and Apache 2.0 License
   4 //  (found in the LICENSE.Apache file in the root directory).
   5
   6 #pragma once
   7
   8 #include <cstddef>
   9 #include <unordered_map>
  10 #ifdef USE_FOLLY
  11 #include <folly/container/F14Map.h>
  12 #endif
  13
  14 #include "rocksdb/rocksdb_namespace.h"
  15
  16 namespace ROCKSDB_NAMESPACE {
  17
  18 // Helper methods to estimate memroy usage by std containers.
  19
  20 template <class Key, class Value, class Hash>
  21 size_t ApproximateMemoryUsage(
  22     const std::unordered_map<Key, Value, Hash>& umap) {
  23   using Map = std::unordered_map<Key, Value, Hash>;
  24   return sizeof(umap) +
  25          // Size of all items plus a next pointer for each item.
  26          (sizeof(typename Map::value_type) + sizeof(void*)) * umap.size() +
  27          // Size of hash buckets.
  28          umap.bucket_count() * sizeof(void*);
  29 }
  30
  31 #ifdef USE_FOLLY
  32 template <class Key, class Value, class Hash>
  33 size_t ApproximateMemoryUsage(const folly::F14FastMap<Key, Value, Hash>& umap) {
  34   return sizeof(umap) + umap.getAllocatedMemorySize();
  35 }
  36 #endif
  37
  38 }  // namespace ROCKSDB_NAMESPACE