mirror of https://github.com/facebook/rocksdb.git
39 lines
1.2 KiB
C++
39 lines
1.2 KiB
C++
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under both the GPLv2 (found in the
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// COPYING file in the root directory) and Apache 2.0 License
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// (found in the LICENSE.Apache file in the root directory).
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#pragma once
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#include <cstddef>
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#include <unordered_map>
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#ifdef USE_FOLLY
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#include <folly/container/F14Map.h>
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#endif
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#include "rocksdb/rocksdb_namespace.h"
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namespace ROCKSDB_NAMESPACE {
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// Helper methods to estimate memroy usage by std containers.
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template <class Key, class Value, class Hash>
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size_t ApproximateMemoryUsage(
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const std::unordered_map<Key, Value, Hash>& umap) {
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using Map = std::unordered_map<Key, Value, Hash>;
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return sizeof(umap) +
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// Size of all items plus a next pointer for each item.
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(sizeof(typename Map::value_type) + sizeof(void*)) * umap.size() +
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// Size of hash buckets.
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umap.bucket_count() * sizeof(void*);
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}
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#ifdef USE_FOLLY
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template <class Key, class Value, class Hash>
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size_t ApproximateMemoryUsage(const folly::F14FastMap<Key, Value, Hash>& umap) {
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return sizeof(umap) + umap.getAllocatedMemorySize();
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}
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#endif
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} // namespace ROCKSDB_NAMESPACE
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