Adding upstream version 18.2.2.upstream/18.2.2

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 38 insertions, 0 deletions

diff --git a/src/rocksdb/memory/memory_usage.h b/src/rocksdb/memory/memory_usage.h
new file mode 100644
index 000000000..76b9bd130
--- /dev/null
+++ b/src/rocksdb/memory/memory_usage.h
@@ -0,0 +1,38 @@
+//  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 <cstddef>
+#include <unordered_map>
+#ifdef USE_FOLLY
+#include <folly/container/F14Map.h>
+#endif
+
+#include "rocksdb/rocksdb_namespace.h"
+
+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*);
+}
+
+#ifdef USE_FOLLY
+template <class Key, class Value, class Hash>
+size_t ApproximateMemoryUsage(const folly::F14FastMap<Key, Value, Hash>& umap) {
+  return sizeof(umap) + umap.getAllocatedMemorySize();
+}
+#endif
+
+}  // namespace ROCKSDB_NAMESPACE