mirror of
https://github.com/facebook/rocksdb.git
synced 2024-11-25 22:44:05 +00:00
c57f914482
Summary: Since the hashes should not be persisted in output_validator nor mock_env. Also updated NPHash64 to use 64-bit seed, and comments. Pull Request resolved: https://github.com/facebook/rocksdb/pull/7632 Test Plan: make check, and new build setting that enables modification to NPHash64, to check for behavior depending on specific values. Added that setting to one of the CircleCI configurations. Reviewed By: jay-zhuang Differential Revision: D24833780 Pulled By: pdillinger fbshipit-source-id: 02a57652ccf1ac105fbca79e77875bb7bf7c071f
108 lines
3.8 KiB
C++
108 lines
3.8 KiB
C++
// 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.
|
|
//
|
|
// Common hash functions with convenient interfaces. If hashing a
|
|
// statically-sized input in a performance-critical context, consider
|
|
// calling a specific hash implementation directly, such as
|
|
// XXH3p_64bits from xxhash.h.
|
|
//
|
|
// Since this is a very common header, implementation details are kept
|
|
// out-of-line. Out-of-lining also aids in tracking the time spent in
|
|
// hashing functions. Inlining is of limited benefit for runtime-sized
|
|
// hash inputs.
|
|
|
|
#pragma once
|
|
|
|
#include <cstddef>
|
|
#include <cstdint>
|
|
|
|
#include "rocksdb/slice.h"
|
|
#include "util/fastrange.h"
|
|
|
|
namespace ROCKSDB_NAMESPACE {
|
|
|
|
// Stable/persistent 64-bit hash. Higher quality and generally faster than
|
|
// Hash(), especially for inputs > 24 bytes.
|
|
// KNOWN FLAW: incrementing seed by 1 might not give sufficiently independent
|
|
// results from previous seed. Recommend incrementing by a large odd number.
|
|
extern uint64_t Hash64(const char* data, size_t n, uint64_t seed);
|
|
|
|
// Specific optimization without seed (same as seed = 0)
|
|
extern uint64_t Hash64(const char* data, size_t n);
|
|
|
|
// Non-persistent hash. Must only used for in-memory data structures.
|
|
// The hash results are thus subject to change between releases,
|
|
// architectures, build configuration, etc. (Thus, it rarely makes sense
|
|
// to specify a seed for this function, except for a "rolling" hash.)
|
|
// KNOWN FLAW: incrementing seed by 1 might not give sufficiently independent
|
|
// results from previous seed. Recommend incrementing by a large odd number.
|
|
inline uint64_t NPHash64(const char* data, size_t n, uint64_t seed) {
|
|
#ifdef ROCKSDB_MODIFY_NPHASH
|
|
// For testing "subject to change"
|
|
return Hash64(data, n, seed + 123456789);
|
|
#else
|
|
// Currently same as Hash64
|
|
return Hash64(data, n, seed);
|
|
#endif
|
|
}
|
|
|
|
// Specific optimization without seed (same as seed = 0)
|
|
inline uint64_t NPHash64(const char* data, size_t n) {
|
|
#ifdef ROCKSDB_MODIFY_NPHASH
|
|
// For testing "subject to change"
|
|
return Hash64(data, n, 123456789);
|
|
#else
|
|
// Currently same as Hash64
|
|
return Hash64(data, n);
|
|
#endif
|
|
}
|
|
|
|
// Stable/persistent 32-bit hash. Moderate quality and high speed on
|
|
// small inputs.
|
|
// TODO: consider rename to Hash32
|
|
// KNOWN FLAW: incrementing seed by 1 might not give sufficiently independent
|
|
// results from previous seed. Recommend pseudorandom or hashed seeds.
|
|
extern uint32_t Hash(const char* data, size_t n, uint32_t seed);
|
|
|
|
// TODO: consider rename to LegacyBloomHash32
|
|
inline uint32_t BloomHash(const Slice& key) {
|
|
return Hash(key.data(), key.size(), 0xbc9f1d34);
|
|
}
|
|
|
|
inline uint64_t GetSliceHash64(const Slice& key) {
|
|
return Hash64(key.data(), key.size());
|
|
}
|
|
|
|
inline uint64_t GetSliceNPHash64(const Slice& s) {
|
|
return NPHash64(s.data(), s.size());
|
|
}
|
|
|
|
inline size_t GetSliceRangedNPHash(const Slice& s, size_t range) {
|
|
return FastRange64(NPHash64(s.data(), s.size()), range);
|
|
}
|
|
|
|
// TODO: consider rename to GetSliceHash32
|
|
inline uint32_t GetSliceHash(const Slice& s) {
|
|
return Hash(s.data(), s.size(), 397);
|
|
}
|
|
|
|
// Useful for splitting up a 64-bit hash
|
|
inline uint32_t Upper32of64(uint64_t v) {
|
|
return static_cast<uint32_t>(v >> 32);
|
|
}
|
|
inline uint32_t Lower32of64(uint64_t v) { return static_cast<uint32_t>(v); }
|
|
|
|
// std::hash compatible interface.
|
|
// TODO: consider rename to SliceHasher32
|
|
struct SliceHasher {
|
|
uint32_t operator()(const Slice& s) const { return GetSliceHash(s); }
|
|
};
|
|
|
|
} // namespace ROCKSDB_NAMESPACE
|