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// Copyright The OpenTelemetry Authors
// SPDX-License-Identifier: Apache-2.0
#pragma once
#include <chrono>
#include <cstdint>
#include "opentelemetry/version.h"
OPENTELEMETRY_BEGIN_NAMESPACE
namespace common
{
/**
* @brief A timepoint relative to the system clock epoch.
*
* This is used for marking the beginning and end of an operation.
*/
class SystemTimestamp
{
public:
/**
* @brief Initializes a system timestamp pointing to the start of the epoch.
*/
SystemTimestamp() noexcept : nanos_since_epoch_{0} {}
/**
* @brief Initializes a system timestamp from a duration.
*
* @param time_since_epoch Time elapsed since the beginning of the epoch.
*/
template <class Rep, class Period>
explicit SystemTimestamp(const std::chrono::duration<Rep, Period> &time_since_epoch) noexcept
: nanos_since_epoch_{static_cast<int64_t>(
std::chrono::duration_cast<std::chrono::nanoseconds>(time_since_epoch).count())}
{}
/**
* @brief Initializes a system timestamp based on a point in time.
*
* @param time_point A point in time.
*/
/*implicit*/ SystemTimestamp(const std::chrono::system_clock::time_point &time_point) noexcept
: SystemTimestamp{time_point.time_since_epoch()}
{}
/**
* @brief Returns a time point for the time stamp.
*
* @return A time point corresponding to the time stamp.
*/
operator std::chrono::system_clock::time_point() const noexcept
{
return std::chrono::system_clock::time_point{
std::chrono::duration_cast<std::chrono::system_clock::duration>(
std::chrono::nanoseconds{nanos_since_epoch_})};
}
/**
* @brief Returns the nanoseconds since the beginning of the epoch.
*
* @return Elapsed nanoseconds since the beginning of the epoch for this timestamp.
*/
std::chrono::nanoseconds time_since_epoch() const noexcept
{
return std::chrono::nanoseconds{nanos_since_epoch_};
}
/**
* @brief Compare two steady time stamps.
*
* @return true if the two time stamps are equal.
*/
bool operator==(const SystemTimestamp &other) const noexcept
{
return nanos_since_epoch_ == other.nanos_since_epoch_;
}
/**
* @brief Compare two steady time stamps for inequality.
*
* @return true if the two time stamps are not equal.
*/
bool operator!=(const SystemTimestamp &other) const noexcept
{
return nanos_since_epoch_ != other.nanos_since_epoch_;
}
private:
int64_t nanos_since_epoch_;
};
/**
* @brief A timepoint relative to the monotonic clock epoch
*
* This is used for calculating the duration of an operation.
*/
class SteadyTimestamp
{
public:
/**
* @brief Initializes a monotonic timestamp pointing to the start of the epoch.
*/
SteadyTimestamp() noexcept : nanos_since_epoch_{0} {}
/**
* @brief Initializes a monotonic timestamp from a duration.
*
* @param time_since_epoch Time elapsed since the beginning of the epoch.
*/
template <class Rep, class Period>
explicit SteadyTimestamp(const std::chrono::duration<Rep, Period> &time_since_epoch) noexcept
: nanos_since_epoch_{static_cast<int64_t>(
std::chrono::duration_cast<std::chrono::nanoseconds>(time_since_epoch).count())}
{}
/**
* @brief Initializes a monotonic timestamp based on a point in time.
*
* @param time_point A point in time.
*/
/*implicit*/ SteadyTimestamp(const std::chrono::steady_clock::time_point &time_point) noexcept
: SteadyTimestamp{time_point.time_since_epoch()}
{}
/**
* @brief Returns a time point for the time stamp.
*
* @return A time point corresponding to the time stamp.
*/
operator std::chrono::steady_clock::time_point() const noexcept
{
return std::chrono::steady_clock::time_point{
std::chrono::duration_cast<std::chrono::steady_clock::duration>(
std::chrono::nanoseconds{nanos_since_epoch_})};
}
/**
* @brief Returns the nanoseconds since the beginning of the epoch.
*
* @return Elapsed nanoseconds since the beginning of the epoch for this timestamp.
*/
std::chrono::nanoseconds time_since_epoch() const noexcept
{
return std::chrono::nanoseconds{nanos_since_epoch_};
}
/**
* @brief Compare two steady time stamps.
*
* @return true if the two time stamps are equal.
*/
bool operator==(const SteadyTimestamp &other) const noexcept
{
return nanos_since_epoch_ == other.nanos_since_epoch_;
}
/**
* @brief Compare two steady time stamps for inequality.
*
* @return true if the two time stamps are not equal.
*/
bool operator!=(const SteadyTimestamp &other) const noexcept
{
return nanos_since_epoch_ != other.nanos_since_epoch_;
}
private:
int64_t nanos_since_epoch_;
};
class DurationUtil
{
public:
template <class Rep, class Period>
static std::chrono::duration<Rep, Period> AdjustWaitForTimeout(
std::chrono::duration<Rep, Period> timeout,
std::chrono::duration<Rep, Period> indefinite_value) noexcept
{
// Do not call now() when this duration is max value, now() may have a expensive cost.
if (timeout == (std::chrono::duration<Rep, Period>::max)())
{
return indefinite_value;
}
// std::future<T>::wait_for, std::this_thread::sleep_for, and std::condition_variable::wait_for
// may use steady_clock or system_clock.We need make sure now() + timeout do not overflow.
auto max_timeout = std::chrono::duration_cast<std::chrono::duration<Rep, Period>>(
(std::chrono::steady_clock::time_point::max)() - std::chrono::steady_clock::now());
if (timeout >= max_timeout)
{
return indefinite_value;
}
max_timeout = std::chrono::duration_cast<std::chrono::duration<Rep, Period>>(
(std::chrono::system_clock::time_point::max)() - std::chrono::system_clock::now());
if (timeout >= max_timeout)
{
return indefinite_value;
}
return timeout;
}
};
} // namespace common
OPENTELEMETRY_END_NAMESPACE
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