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rocksdb/third-party/folly/folly/chrono/Hardware.h

33 lines
891 B

// 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 <folly/Portability.h>
#include <chrono>
#include <cstdint>
#if _MSC_VER && (defined(_M_IX86) || defined(_M_X64))
extern "C" std::uint64_t __rdtsc();
#pragma intrinsic(__rdtsc)
#endif
namespace folly {
inline std::uint64_t hardware_timestamp() {
#if _MSC_VER && (defined(_M_IX86) || defined(_M_X64))
return __rdtsc();
#elif __GNUC__ && (__i386__ || FOLLY_X64)
return __builtin_ia32_rdtsc();
#else
// use steady_clock::now() as an approximation for the timestamp counter on
// non-x86 systems
return std::chrono::steady_clock::now().time_since_epoch().count();
#endif
}
} // namespace folly