Viewing file:  Chrono.h (6.73 KB) -rw-r--r--
Select action/file-type:
 (+) |  (+) |  (+) | Code (+) | Session (+) |  (+) | SDB (+) |  (+) |  (+) |  (+) |  (+) |  (+) |
//===- llvm/Support/Chrono.h - Utilities for Timing Manipulation-*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_SUPPORT_CHRONO_H
#define LLVM_SUPPORT_CHRONO_H
#include "llvm/Support/Compiler.h"
#include "llvm/Support/FormatProviders.h"
#include <chrono>
#include <ctime>
#include <ratio>
namespace llvm {
class raw_ostream;
namespace sys {
/// A time point on the system clock. This is provided for two reasons:
/// - to insulate us against subtle differences in behavior to differences in
/// system clock precision (which is implementation-defined and differs
/// between platforms).
/// - to shorten the type name
/// The default precision is nanoseconds. If you need a specific precision
/// specify it explicitly. If unsure, use the default. If you need a time point
/// on a clock other than the system_clock, use std::chrono directly.
template <typename D = std::chrono::nanoseconds>
using TimePoint = std::chrono::time_point<std::chrono::system_clock, D>;
// utc_clock and utc_time are only available since C++20. Add enough code to
// support formatting date/time in UTC.
class UtcClock : public std::chrono::system_clock {};
template <typename D = std::chrono::nanoseconds>
using UtcTime = std::chrono::time_point<UtcClock, D>;
/// Convert a std::time_t to a UtcTime
inline UtcTime<std::chrono::seconds> toUtcTime(std::time_t T) {
using namespace std::chrono;
return UtcTime<seconds>(seconds(T));
}
/// Convert a TimePoint to std::time_t
inline std::time_t toTimeT(TimePoint<> TP) {
using namespace std::chrono;
return system_clock::to_time_t(
time_point_cast<system_clock::time_point::duration>(TP));
}
/// Convert a UtcTime to std::time_t
inline std::time_t toTimeT(UtcTime<> TP) {
using namespace std::chrono;
return system_clock::to_time_t(time_point<system_clock, seconds>(
duration_cast<seconds>(TP.time_since_epoch())));
}
/// Convert a std::time_t to a TimePoint
inline TimePoint<std::chrono::seconds>
toTimePoint(std::time_t T) {
using namespace std::chrono;
return time_point_cast<seconds>(system_clock::from_time_t(T));
}
/// Convert a std::time_t + nanoseconds to a TimePoint
inline TimePoint<>
toTimePoint(std::time_t T, uint32_t nsec) {
using namespace std::chrono;
return time_point_cast<nanoseconds>(system_clock::from_time_t(T))
+ nanoseconds(nsec);
}
} // namespace sys
raw_ostream &operator<<(raw_ostream &OS, sys::TimePoint<> TP);
raw_ostream &operator<<(raw_ostream &OS, sys::UtcTime<> TP);
/// Format provider for TimePoint<>
///
/// The options string is a strftime format string, with extensions:
/// - %L is millis: 000-999
/// - %f is micros: 000000-999999
/// - %N is nanos: 000000000 - 999999999
///
/// If no options are given, the default format is "%Y-%m-%d %H:%M:%S.%N".
template <>
struct format_provider<sys::TimePoint<>> {
static void format(const sys::TimePoint<> &TP, llvm::raw_ostream &OS,
StringRef Style);
};
template <> struct format_provider<sys::UtcTime<std::chrono::seconds>> {
static void format(const sys::UtcTime<std::chrono::seconds> &TP,
llvm::raw_ostream &OS, StringRef Style);
};
namespace detail {
template <typename Period> struct unit { static const char value[]; };
template <typename Period> const char unit<Period>::value[] = "";
template <> struct unit<std::ratio<3600>> { static const char value[]; };
template <> struct unit<std::ratio<60>> { static const char value[]; };
template <> struct unit<std::ratio<1>> { static const char value[]; };
template <> struct unit<std::milli> { static const char value[]; };
template <> struct unit<std::micro> { static const char value[]; };
template <> struct unit<std::nano> { static const char value[]; };
} // namespace detail
/// Implementation of format_provider<T> for duration types.
///
/// The options string of a duration type has the grammar:
///
/// duration_options ::= [unit][show_unit [number_options]]
/// unit ::= `h`|`m`|`s`|`ms|`us`|`ns`
/// show_unit ::= `+` | `-`
/// number_options ::= options string for a integral or floating point type
///
/// Examples
/// =================================
/// | options | Input | Output |
/// =================================
/// | "" | 1s | 1 s |
/// | "ms" | 1s | 1000 ms |
/// | "ms-" | 1s | 1000 |
/// | "ms-n" | 1s | 1,000 |
/// | "" | 1.0s | 1.00 s |
/// =================================
///
/// If the unit of the duration type is not one of the units specified above,
/// it is still possible to format it, provided you explicitly request a
/// display unit or you request that the unit is not displayed.
template <typename Rep, typename Period>
struct format_provider<std::chrono::duration<Rep, Period>> {
private:
typedef std::chrono::duration<Rep, Period> Dur;
typedef std::conditional_t<std::chrono::treat_as_floating_point<Rep>::value,
double, intmax_t>
InternalRep;
template <typename AsPeriod> static InternalRep getAs(const Dur &D) {
using namespace std::chrono;
return duration_cast<duration<InternalRep, AsPeriod>>(D).count();
}
static std::pair<InternalRep, StringRef> consumeUnit(StringRef &Style,
const Dur &D) {
using namespace std::chrono;
if (Style.consume_front("ns"))
return {getAs<std::nano>(D), "ns"};
if (Style.consume_front("us"))
return {getAs<std::micro>(D), "us"};
if (Style.consume_front("ms"))
return {getAs<std::milli>(D), "ms"};
if (Style.consume_front("s"))
return {getAs<std::ratio<1>>(D), "s"};
if (Style.consume_front("m"))
return {getAs<std::ratio<60>>(D), "m"};
if (Style.consume_front("h"))
return {getAs<std::ratio<3600>>(D), "h"};
return {D.count(), detail::unit<Period>::value};
}
static bool consumeShowUnit(StringRef &Style) {
if (Style.empty())
return true;
if (Style.consume_front("-"))
return false;
if (Style.consume_front("+"))
return true;
assert(0 && "Unrecognised duration format");
return true;
}
public:
static void format(const Dur &D, llvm::raw_ostream &Stream, StringRef Style) {
InternalRep count;
StringRef unit;
std::tie(count, unit) = consumeUnit(Style, D);
bool show_unit = consumeShowUnit(Style);
format_provider<InternalRep>::format(count, Stream, Style);
if (show_unit) {
assert(!unit.empty());
Stream << " " << unit;
}
}
};
} // namespace llvm
#endif // LLVM_SUPPORT_CHRONO_H
|