rocksdb/util/cast_util.h
Peter Dillinger 653c392e47 More refactoring ahead of footer & meta changes (#9240)
Summary:
I'm working on a new format_version=6 to support context
checksum (https://github.com/facebook/rocksdb/issues/9058) and this includes much of the refactoring and test
updates to support that change.

Test coverage data and manual inspection agree on dead code in
block_based_table_reader.cc (removed).

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9240

Test Plan:
tests enhanced to cover more cases etc.

Extreme case performance testing indicates small % regression in fillseq (w/ compaction), though CPU profile etc. doesn't suggest any explanation. There is enhanced correctness checking in Footer::DecodeFrom, but this should be negligible.

TEST_TMPDIR=/dev/shm/ ./db_bench -benchmarks=fillseq -memtablerep=vector -allow_concurrent_memtable_write=false -num=30000000 -checksum_type=1 --disable_wal={false,true}

(Each is ops/s averaged over 50 runs, run simultaneously with competing configuration for load fairness)
Before w/ wal: 454512
After w/ wal: 444820 (-2.1%)
Before w/o wal: 1004560
After w/o wal: 998897 (-0.6%)

Since this doesn't modify WAL code, one would expect real effects to be larger in w/o wal case.

This regression will be corrected in a follow-up PR.

Reviewed By: ajkr

Differential Revision: D32813769

Pulled By: pdillinger

fbshipit-source-id: 444a244eabf3825cd329b7d1b150cddce320862f
2021-12-10 08:13:26 -08:00

43 lines
1.7 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).
#pragma once
#include <type_traits>
#include "rocksdb/rocksdb_namespace.h"
namespace ROCKSDB_NAMESPACE {
// The helper function to assert the move from dynamic_cast<> to
// static_cast<> is correct. This function is to deal with legacy code.
// It is not recommended to add new code to issue class casting. The preferred
// solution is to implement the functionality without a need of casting.
template <class DestClass, class SrcClass>
inline DestClass* static_cast_with_check(SrcClass* x) {
DestClass* ret = static_cast<DestClass*>(x);
#ifdef ROCKSDB_USE_RTTI
assert(ret == dynamic_cast<DestClass*>(x));
#endif
return ret;
}
// A wrapper around static_cast for lossless conversion between integral
// types, including enum types. For example, this can be used for converting
// between signed/unsigned or enum type and underlying type without fear of
// stripping away data, now or in the future.
template <typename To, typename From>
inline To lossless_cast(From x) {
using FromValue = typename std::remove_reference<From>::type;
static_assert(
std::is_integral<FromValue>::value || std::is_enum<FromValue>::value,
"Only works on integral types");
static_assert(std::is_integral<To>::value || std::is_enum<To>::value,
"Only works on integral types");
static_assert(sizeof(To) >= sizeof(FromValue), "Must be lossless");
return static_cast<To>(x);
}
} // namespace ROCKSDB_NAMESPACE