116 lines
3.5 KiB
C
116 lines
3.5 KiB
C
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/*
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* Copyright (c) Meta Platforms, Inc. and affiliates.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*/
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#pragma once
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#include <chrono>
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#include <type_traits>
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namespace facebook {
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namespace react {
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/*
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* Represents a monotonic clock suitable for measuring intervals.
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*/
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using TelemetryClock = std::chrono::steady_clock;
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/*
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* Represents a point in time satisfied the requirements of TelemetryClock.
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*/
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using TelemetryTimePoint = TelemetryClock::time_point;
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/*
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* Represents a time interval satisfied the requirements of TelemetryClock.
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*/
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using TelemetryDuration = std::chrono::nanoseconds;
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/*
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* Represents a time point which never happens.
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*/
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static TelemetryTimePoint const kTelemetryUndefinedTimePoint =
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TelemetryTimePoint::max();
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/*
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* Returns a time point representing the current point in time.
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*/
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static inline TelemetryTimePoint telemetryTimePointNow() {
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return TelemetryClock::now();
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}
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/*
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* Returns a number of milliseconds that passed from some epoch starting time
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* point to a given time point. The epoch starting time point is not specified
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* but stays the same for an application run.
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*/
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static inline int64_t telemetryTimePointToMilliseconds(
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TelemetryTimePoint timePoint) {
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return std::chrono::duration_cast<std::chrono::milliseconds>(
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timePoint - TelemetryTimePoint{})
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.count();
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}
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/*
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* Returns a number of seconds that passed from "Steady Clock" epoch starting
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* time point to a given time point.
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*/
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static inline double telemetryTimePointToSteadyClockSeconds(
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TelemetryTimePoint timePoint) {
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static_assert(
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std::is_same<decltype(timePoint), std::chrono::steady_clock::time_point>::
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value,
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"`TelemetryClock` must be `std::chrono::steady_clock` to make the "
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"following implementation work correctly.");
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auto nanoseconds = std::chrono::duration_cast<std::chrono::nanoseconds>(
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timePoint.time_since_epoch())
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.count();
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return (double)nanoseconds / 1.0e9;
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}
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/*
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* Converts a time point on one clock to a time point on a different clock.
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*/
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template <
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typename DestinationTimePointT,
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typename SourceTimePointT,
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typename DestnationClockT = typename DestinationTimePointT::clock,
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typename SourceClockT = typename SourceTimePointT::clock>
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DestinationTimePointT clockCast(SourceTimePointT timePoint) {
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auto sourseClockNow = SourceClockT::now();
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auto destinationClockNow = DestnationClockT::now();
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return std::chrono::time_point_cast<typename DestnationClockT::duration>(
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timePoint - sourseClockNow + destinationClockNow);
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}
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/*
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* Returns a number of seconds that passed from the UNIX Epoch starting time
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* point to a given time point.
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* Also known as POSIX time or UNIX Timestamp.
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*/
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static inline double telemetryTimePointToSecondsSinceEpoch(
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TelemetryTimePoint timePoint) {
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auto systemClockTimePoint =
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clockCast<std::chrono::system_clock::time_point, TelemetryTimePoint>(
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timePoint);
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return (double)std::chrono::duration_cast<std::chrono::microseconds>(
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systemClockTimePoint.time_since_epoch())
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.count() /
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1000000.0;
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}
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/*
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* Returns a number of milliseconds that represents the given duration object.
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*/
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static inline int64_t telemetryDurationToMilliseconds(
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TelemetryDuration duration) {
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return std::chrono::duration_cast<std::chrono::milliseconds>(duration)
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.count();
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}
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} // namespace react
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} // namespace facebook
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