1//===- llvm/Support/Chrono.h - Utilities for Timing Manipulation-*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#ifndef LLVM_SUPPORT_CHRONO_H
10#define LLVM_SUPPORT_CHRONO_H
11
12#include "llvm/Support/Compiler.h"
13#include "llvm/Support/FormatProviders.h"
14
15#include <chrono>
16#include <ctime>
17#include <ratio>
18
19namespace llvm {
20
21class raw_ostream;
22
23namespace sys {
24
25/// A time point on the system clock. This is provided for two reasons:
26/// - to insulate us against subtle differences in behavior to differences in
27/// system clock precision (which is implementation-defined and differs
28/// between platforms).
29/// - to shorten the type name
30/// The default precision is nanoseconds. If you need a specific precision
31/// specify it explicitly. If unsure, use the default. If you need a time point
32/// on a clock other than the system_clock, use std::chrono directly.
33template <typename D = std::chrono::nanoseconds>
34using TimePoint = std::chrono::time_point<std::chrono::system_clock, D>;
35
36/// Convert a TimePoint to std::time_t
37inline std::time_t toTimeT(TimePoint<> TP) {
38 using namespace std::chrono;
39 return system_clock::to_time_t(
40 t: time_point_cast<system_clock::time_point::duration>(t: TP));
41}
42
43/// Convert a std::time_t to a TimePoint
44inline TimePoint<std::chrono::seconds>
45toTimePoint(std::time_t T) {
46 using namespace std::chrono;
47 return time_point_cast<seconds>(t: system_clock::from_time_t(t: T));
48}
49
50/// Convert a std::time_t + nanoseconds to a TimePoint
51inline TimePoint<>
52toTimePoint(std::time_t T, uint32_t nsec) {
53 using namespace std::chrono;
54 return time_point_cast<nanoseconds>(t: system_clock::from_time_t(t: T))
55 + nanoseconds(nsec);
56}
57
58} // namespace sys
59
60raw_ostream &operator<<(raw_ostream &OS, sys::TimePoint<> TP);
61
62/// Format provider for TimePoint<>
63///
64/// The options string is a strftime format string, with extensions:
65/// - %L is millis: 000-999
66/// - %f is micros: 000000-999999
67/// - %N is nanos: 000000000 - 999999999
68///
69/// If no options are given, the default format is "%Y-%m-%d %H:%M:%S.%N".
70template <>
71struct format_provider<sys::TimePoint<>> {
72 static void format(const sys::TimePoint<> &TP, llvm::raw_ostream &OS,
73 StringRef Style);
74};
75
76namespace detail {
77template <typename Period> struct unit { static const char value[]; };
78template <typename Period> const char unit<Period>::value[] = "";
79
80template <> struct unit<std::ratio<3600>> { static const char value[]; };
81template <> struct unit<std::ratio<60>> { static const char value[]; };
82template <> struct unit<std::ratio<1>> { static const char value[]; };
83template <> struct unit<std::milli> { static const char value[]; };
84template <> struct unit<std::micro> { static const char value[]; };
85template <> struct unit<std::nano> { static const char value[]; };
86} // namespace detail
87
88/// Implementation of format_provider<T> for duration types.
89///
90/// The options string of a duration type has the grammar:
91///
92/// duration_options ::= [unit][show_unit [number_options]]
93/// unit ::= `h`|`m`|`s`|`ms|`us`|`ns`
94/// show_unit ::= `+` | `-`
95/// number_options ::= options string for a integral or floating point type
96///
97/// Examples
98/// =================================
99/// | options | Input | Output |
100/// =================================
101/// | "" | 1s | 1 s |
102/// | "ms" | 1s | 1000 ms |
103/// | "ms-" | 1s | 1000 |
104/// | "ms-n" | 1s | 1,000 |
105/// | "" | 1.0s | 1.00 s |
106/// =================================
107///
108/// If the unit of the duration type is not one of the units specified above,
109/// it is still possible to format it, provided you explicitly request a
110/// display unit or you request that the unit is not displayed.
111
112template <typename Rep, typename Period>
113struct format_provider<std::chrono::duration<Rep, Period>> {
114private:
115 typedef std::chrono::duration<Rep, Period> Dur;
116 typedef std::conditional_t<std::chrono::treat_as_floating_point<Rep>::value,
117 double, intmax_t>
118 InternalRep;
119
120 template <typename AsPeriod> static InternalRep getAs(const Dur &D) {
121 using namespace std::chrono;
122 return duration_cast<duration<InternalRep, AsPeriod>>(D).count();
123 }
124
125 static std::pair<InternalRep, StringRef> consumeUnit(StringRef &Style,
126 const Dur &D) {
127 using namespace std::chrono;
128 if (Style.consume_front(Prefix: "ns"))
129 return {getAs<std::nano>(D), "ns"};
130 if (Style.consume_front(Prefix: "us"))
131 return {getAs<std::micro>(D), "us"};
132 if (Style.consume_front(Prefix: "ms"))
133 return {getAs<std::milli>(D), "ms"};
134 if (Style.consume_front(Prefix: "s"))
135 return {getAs<std::ratio<1>>(D), "s"};
136 if (Style.consume_front(Prefix: "m"))
137 return {getAs<std::ratio<60>>(D), "m"};
138 if (Style.consume_front(Prefix: "h"))
139 return {getAs<std::ratio<3600>>(D), "h"};
140 return {D.count(), detail::unit<Period>::value};
141 }
142
143 static bool consumeShowUnit(StringRef &Style) {
144 if (Style.empty())
145 return true;
146 if (Style.consume_front(Prefix: "-"))
147 return false;
148 if (Style.consume_front(Prefix: "+"))
149 return true;
150 assert(0 && "Unrecognised duration format");
151 return true;
152 }
153
154public:
155 static void format(const Dur &D, llvm::raw_ostream &Stream, StringRef Style) {
156 InternalRep count;
157 StringRef unit;
158 std::tie(count, unit) = consumeUnit(Style, D);
159 bool show_unit = consumeShowUnit(Style);
160
161 format_provider<InternalRep>::format(count, Stream, Style);
162
163 if (show_unit) {
164 assert(!unit.empty());
165 Stream << " " << unit;
166 }
167 }
168};
169
170} // namespace llvm
171
172#endif // LLVM_SUPPORT_CHRONO_H
173

source code of include/llvm-17/llvm/Support/Chrono.h