/*
- * Copyright 2014 Facebook, Inc.
+ * Copyright 2017-present Facebook, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* limitations under the License.
*/
-// Wrapper around <chrono> that hides away some gcc 4.6 issues
-#ifndef FOLLY_CHRONO_H_
-#define FOLLY_CHRONO_H_
+#pragma once
#include <chrono>
+#include <stdexcept>
+#include <type_traits>
+
#include <folly/Portability.h>
+#include <folly/portability/Time.h>
+
+/***
+ * include or backport:
+ * * std::chrono::ceil
+ * * std::chrono::floor
+ * * std::chrono::round
+ */
+
+#if __cpp_lib_chrono >= 201510 || _MSC_VER
+
+namespace folly {
+namespace chrono {
+
+/* using override */ using std::chrono::ceil;
+/* using override */ using std::chrono::floor;
+/* using override */ using std::chrono::round;
+}
+}
+
+#else
+
+namespace folly {
+namespace chrono {
+
+namespace detail {
+
+// from: http://en.cppreference.com/w/cpp/chrono/duration/ceil, CC-BY-SA
+template <typename T>
+struct is_duration : std::false_type {};
+template <typename Rep, typename Period>
+struct is_duration<std::chrono::duration<Rep, Period>> : std::true_type {};
+
+template <typename To, typename Duration>
+constexpr To ceil_impl(Duration const& d, To const& t) {
+ return t < d ? t + To{1} : t;
+}
+
+template <typename To, typename Duration>
+constexpr To floor_impl(Duration const& d, To const& t) {
+ return t > d ? t - To{1} : t;
+}
+
+template <typename To, typename Diff>
+constexpr To round_impl(To const& t0, To const& t1, Diff diff0, Diff diff1) {
+ return diff0 < diff1 ? t0 : diff1 < diff0 ? t1 : t0.count() & 1 ? t1 : t0;
+}
+
+template <typename To, typename Duration>
+constexpr To round_impl(Duration const& d, To const& t0, To const& t1) {
+ return round_impl(t0, t1, d - t0, t1 - d);
+}
+
+template <typename To, typename Duration>
+constexpr To round_impl(Duration const& d, To const& t0) {
+ return round_impl(d, t0, t0 + To{1});
+}
+} // namespace detail
+
+// mimic: std::chrono::ceil, C++17
+// from: http://en.cppreference.com/w/cpp/chrono/duration/ceil, CC-BY-SA
+template <
+ typename To,
+ typename Rep,
+ typename Period,
+ typename = typename std::enable_if<detail::is_duration<To>::value>::type>
+constexpr To ceil(std::chrono::duration<Rep, Period> const& d) {
+ return detail::ceil_impl(d, std::chrono::duration_cast<To>(d));
+}
+
+// mimic: std::chrono::ceil, C++17
+// from: http://en.cppreference.com/w/cpp/chrono/time_point/ceil, CC-BY-SA
+template <
+ typename To,
+ typename Clock,
+ typename Duration,
+ typename = typename std::enable_if<detail::is_duration<To>::value>::type>
+constexpr std::chrono::time_point<Clock, To> ceil(
+ std::chrono::time_point<Clock, Duration> const& tp) {
+ return std::chrono::time_point<Clock, To>{ceil<To>(tp.time_since_epoch())};
+}
+
+// mimic: std::chrono::floor, C++17
+// from: http://en.cppreference.com/w/cpp/chrono/duration/floor, CC-BY-SA
+template <
+ typename To,
+ typename Rep,
+ typename Period,
+ typename = typename std::enable_if<detail::is_duration<To>::value>::type>
+constexpr To floor(std::chrono::duration<Rep, Period> const& d) {
+ return detail::floor_impl(d, std::chrono::duration_cast<To>(d));
+}
+
+// mimic: std::chrono::floor, C++17
+// from: http://en.cppreference.com/w/cpp/chrono/time_point/floor, CC-BY-SA
+template <
+ typename To,
+ typename Clock,
+ typename Duration,
+ typename = typename std::enable_if<detail::is_duration<To>::value>::type>
+constexpr std::chrono::time_point<Clock, To> floor(
+ std::chrono::time_point<Clock, Duration> const& tp) {
+ return std::chrono::time_point<Clock, To>{floor<To>(tp.time_since_epoch())};
+}
+
+// mimic: std::chrono::round, C++17
+// from: http://en.cppreference.com/w/cpp/chrono/duration/round, CC-BY-SA
+template <
+ typename To,
+ typename Rep,
+ typename Period,
+ typename = typename std::enable_if<
+ detail::is_duration<To>::value &&
+ !std::chrono::treat_as_floating_point<typename To::rep>::value>::type>
+constexpr To round(std::chrono::duration<Rep, Period> const& d) {
+ return detail::round_impl(d, floor<To>(d));
+}
+
+// mimic: std::chrono::round, C++17
+// from: http://en.cppreference.com/w/cpp/chrono/time_point/round, CC-BY-SA
+template <
+ typename To,
+ typename Clock,
+ typename Duration,
+ typename = typename std::enable_if<
+ detail::is_duration<To>::value &&
+ !std::chrono::treat_as_floating_point<typename To::rep>::value>::type>
+constexpr std::chrono::time_point<Clock, To> round(
+ std::chrono::time_point<Clock, Duration> const& tp) {
+ return std::chrono::time_point<Clock, To>{round<To>(tp.time_since_epoch())};
+}
+} // namespace chrono
+} // namespace folly
-// gcc 4.6 uses an obsolete name for steady_clock, although the implementation
-// is the same
-#if __GNUC_PREREQ(4, 6) && !__GNUC_PREREQ(4, 7)
-namespace std { namespace chrono {
-typedef monotonic_clock steady_clock;
-}} // namespaces
#endif
-#endif /* FOLLY_CHRONO_H_ */
+namespace folly {
+namespace chrono {
+namespace detail {
+[[noreturn]] FOLLY_NOINLINE inline void throw_coarse_steady_clock_now_exn() {
+ throw std::runtime_error("Error using CLOCK_MONOTONIC_COARSE.");
+}
+} // namespace detail
+
+struct coarse_steady_clock {
+ using rep = std::chrono::milliseconds::rep;
+ using period = std::chrono::milliseconds::period;
+ using duration = std::chrono::duration<rep, period>;
+ using time_point = std::chrono::time_point<coarse_steady_clock, duration>;
+ constexpr static bool is_steady = true;
+
+ static time_point now() {
+#ifndef CLOCK_MONOTONIC_COARSE
+ return time_point(std::chrono::duration_cast<duration>(
+ std::chrono::steady_clock::now().time_since_epoch()));
+#else
+ timespec ts;
+ auto ret = clock_gettime(CLOCK_MONOTONIC_COARSE, &ts);
+ if (ret != 0) {
+ detail::throw_coarse_steady_clock_now_exn();
+ }
+ return time_point(std::chrono::duration_cast<duration>(
+ std::chrono::seconds(ts.tv_sec) +
+ std::chrono::nanoseconds(ts.tv_nsec)));
+#endif
+ }
+};
+} // namespace chrono
+} // namespace folly
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