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Diffstat (limited to 'third_party/abseil_cpp/absl/base/internal/cycleclock.h')
| -rw-r--r-- | third_party/abseil_cpp/absl/base/internal/cycleclock.h | 94 |
1 files changed, 0 insertions, 94 deletions
diff --git a/third_party/abseil_cpp/absl/base/internal/cycleclock.h b/third_party/abseil_cpp/absl/base/internal/cycleclock.h deleted file mode 100644 index a18b584445..0000000000 --- a/third_party/abseil_cpp/absl/base/internal/cycleclock.h +++ /dev/null @@ -1,94 +0,0 @@ -// -// Copyright 2017 The Abseil Authors. -// -// Licensed under the Apache License, Version 2.0 (the "License"); -// you may not use this file except in compliance with the License. -// You may obtain a copy of the License at -// -// https://www.apache.org/licenses/LICENSE-2.0 -// -// Unless required by applicable law or agreed to in writing, software -// distributed under the License is distributed on an "AS IS" BASIS, -// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. -// See the License for the specific language governing permissions and -// limitations under the License. -// - -// ----------------------------------------------------------------------------- -// File: cycleclock.h -// ----------------------------------------------------------------------------- -// -// This header file defines a `CycleClock`, which yields the value and frequency -// of a cycle counter that increments at a rate that is approximately constant. -// -// NOTE: -// -// The cycle counter frequency is not necessarily related to the core clock -// frequency and should not be treated as such. That is, `CycleClock` cycles are -// not necessarily "CPU cycles" and code should not rely on that behavior, even -// if experimentally observed. -// -// An arbitrary offset may have been added to the counter at power on. -// -// On some platforms, the rate and offset of the counter may differ -// slightly when read from different CPUs of a multiprocessor. Usually, -// we try to ensure that the operating system adjusts values periodically -// so that values agree approximately. If you need stronger guarantees, -// consider using alternate interfaces. -// -// The CPU is not required to maintain the ordering of a cycle counter read -// with respect to surrounding instructions. - -#ifndef ABSL_BASE_INTERNAL_CYCLECLOCK_H_ -#define ABSL_BASE_INTERNAL_CYCLECLOCK_H_ - -#include <cstdint> - -#include "absl/base/config.h" - -namespace absl { -ABSL_NAMESPACE_BEGIN -namespace base_internal { - -// ----------------------------------------------------------------------------- -// CycleClock -// ----------------------------------------------------------------------------- -class CycleClock { - public: - // CycleClock::Now() - // - // Returns the value of a cycle counter that counts at a rate that is - // approximately constant. - static int64_t Now(); - - // CycleClock::Frequency() - // - // Returns the amount by which `CycleClock::Now()` increases per second. Note - // that this value may not necessarily match the core CPU clock frequency. - static double Frequency(); - - private: - CycleClock() = delete; // no instances - CycleClock(const CycleClock&) = delete; - CycleClock& operator=(const CycleClock&) = delete; -}; - -using CycleClockSourceFunc = int64_t (*)(); - -class CycleClockSource { - private: - // CycleClockSource::Register() - // - // Register a function that provides an alternate source for the unscaled CPU - // cycle count value. The source function must be async signal safe, must not - // call CycleClock::Now(), and must have a frequency that matches that of the - // unscaled clock used by CycleClock. A nullptr value resets CycleClock to use - // the default source. - static void Register(CycleClockSourceFunc source); -}; - -} // namespace base_internal -ABSL_NAMESPACE_END -} // namespace absl - -#endif // ABSL_BASE_INTERNAL_CYCLECLOCK_H_ |