1 files changed, 52 insertions, 0 deletions
diff --git a/src/rocksdb/util/hash.h b/src/rocksdb/util/hash.h
new file mode 100644
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--- /dev/null
+++ b/src/rocksdb/util/hash.h
@@ -0,0 +1,52 @@
+//  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).
+//
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+//
+// Simple hash function used for internal data structures
+
+#pragma once
+#include <stddef.h>
+#include <stdint.h>
+
+#include "rocksdb/slice.h"
+#include "util/murmurhash.h"
+
+namespace rocksdb {
+
+// Non-persistent hash. Only used for in-memory data structure
+// The hash results are applicable to change.
+extern uint64_t NPHash64(const char* data, size_t n, uint32_t seed);
+
+extern uint32_t Hash(const char* data, size_t n, uint32_t seed);
+
+inline uint32_t BloomHash(const Slice& key) {
+  return Hash(key.data(), key.size(), 0xbc9f1d34);
+}
+
+inline uint64_t GetSliceNPHash64(const Slice& s) {
+  return NPHash64(s.data(), s.size(), 0);
+}
+
+inline uint32_t GetSliceHash(const Slice& s) {
+  return Hash(s.data(), s.size(), 397);
+}
+
+inline uint64_t NPHash64(const char* data, size_t n, uint32_t seed) {
+  // Right now murmurhash2B is used. It should able to be freely
+  // changed to a better hash, without worrying about backward
+  // compatibility issue.
+  return MURMUR_HASH(data, static_cast<int>(n),
+                     static_cast<unsigned int>(seed));
+}
+
+// std::hash compatible interface.
+struct SliceHasher {
+  uint32_t operator()(const Slice& s) const { return GetSliceHash(s); }
+};
+
+}  // namespace rocksdb