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// 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
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