44 lines
1.2 KiB
C++
44 lines
1.2 KiB
C++
/*
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#pragma once
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#include <folly/Portability.h>
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#include <chrono>
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#include <cstdint>
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#if defined(_MSC_VER)
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extern "C" std::uint64_t __rdtsc();
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#pragma intrinsic(__rdtsc)
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#endif
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namespace folly {
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inline std::uint64_t hardware_timestamp() {
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#if defined(_MSC_VER)
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return __rdtsc();
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#elif defined(__GNUC__) && (defined(__i386__) || FOLLY_X64)
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return __builtin_ia32_rdtsc();
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#else
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// use steady_clock::now() as an approximation for the timestamp counter on
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// non-x86 systems
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return std::chrono::steady_clock::now().time_since_epoch().count();
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#endif
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}
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} // namespace folly
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