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
19 namespace llvm {
20
21 class raw_ostream;
22
23 namespace 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.
33 template <typename D = std::chrono::nanoseconds>
34 using TimePoint = std::chrono::time_point<std::chrono::system_clock, D>;
35
36 // utc_clock and utc_time are only available since C++20. Add enough code to
37 // support formatting date/time in UTC.
38 class UtcClock : public std::chrono::system_clock {};
39
40 template <typename D = std::chrono::nanoseconds>
41 using UtcTime = std::chrono::time_point<UtcClock, D>;
42
43 /// Convert a std::time_t to a UtcTime
toUtcTime(std::time_t T)44 inline UtcTime<std::chrono::seconds> toUtcTime(std::time_t T) {
45 using namespace std::chrono;
46 return UtcTime<seconds>(seconds(T));
47 }
48
49 /// Convert a TimePoint to std::time_t
toTimeT(TimePoint<> TP)50 inline std::time_t toTimeT(TimePoint<> TP) {
51 using namespace std::chrono;
52 return system_clock::to_time_t(
53 time_point_cast<system_clock::time_point::duration>(TP));
54 }
55
56 /// Convert a UtcTime to std::time_t
toTimeT(UtcTime<> TP)57 inline std::time_t toTimeT(UtcTime<> TP) {
58 using namespace std::chrono;
59 return system_clock::to_time_t(time_point<system_clock, seconds>(
60 duration_cast<seconds>(TP.time_since_epoch())));
61 }
62
63 /// Convert a std::time_t to a TimePoint
64 inline TimePoint<std::chrono::seconds>
toTimePoint(std::time_t T)65 toTimePoint(std::time_t T) {
66 using namespace std::chrono;
67 return time_point_cast<seconds>(system_clock::from_time_t(T));
68 }
69
70 /// Convert a std::time_t + nanoseconds to a TimePoint
71 inline TimePoint<>
toTimePoint(std::time_t T,uint32_t nsec)72 toTimePoint(std::time_t T, uint32_t nsec) {
73 using namespace std::chrono;
74 return time_point_cast<nanoseconds>(system_clock::from_time_t(T))
75 + nanoseconds(nsec);
76 }
77
78 } // namespace sys
79
80 raw_ostream &operator<<(raw_ostream &OS, sys::TimePoint<> TP);
81 raw_ostream &operator<<(raw_ostream &OS, sys::UtcTime<> TP);
82
83 /// Format provider for TimePoint<>
84 ///
85 /// The options string is a strftime format string, with extensions:
86 /// - %L is millis: 000-999
87 /// - %f is micros: 000000-999999
88 /// - %N is nanos: 000000000 - 999999999
89 ///
90 /// If no options are given, the default format is "%Y-%m-%d %H:%M:%S.%N".
91 template <>
92 struct format_provider<sys::TimePoint<>> {
93 static void format(const sys::TimePoint<> &TP, llvm::raw_ostream &OS,
94 StringRef Style);
95 };
96
97 template <> struct format_provider<sys::UtcTime<std::chrono::seconds>> {
98 static void format(const sys::UtcTime<std::chrono::seconds> &TP,
99 llvm::raw_ostream &OS, StringRef Style);
100 };
101
102 namespace detail {
103 template <typename Period> struct unit { static const char value[]; };
104 template <typename Period> const char unit<Period>::value[] = "";
105
106 template <> struct unit<std::ratio<3600>> { static const char value[]; };
107 template <> struct unit<std::ratio<60>> { static const char value[]; };
108 template <> struct unit<std::ratio<1>> { static const char value[]; };
109 template <> struct unit<std::milli> { static const char value[]; };
110 template <> struct unit<std::micro> { static const char value[]; };
111 template <> struct unit<std::nano> { static const char value[]; };
112 } // namespace detail
113
114 /// Implementation of format_provider<T> for duration types.
115 ///
116 /// The options string of a duration type has the grammar:
117 ///
118 /// duration_options ::= [unit][show_unit [number_options]]
119 /// unit ::= `h`|`m`|`s`|`ms|`us`|`ns`
120 /// show_unit ::= `+` | `-`
121 /// number_options ::= options string for a integral or floating point type
122 ///
123 /// Examples
124 /// =================================
125 /// | options | Input | Output |
126 /// =================================
127 /// | "" | 1s | 1 s |
128 /// | "ms" | 1s | 1000 ms |
129 /// | "ms-" | 1s | 1000 |
130 /// | "ms-n" | 1s | 1,000 |
131 /// | "" | 1.0s | 1.00 s |
132 /// =================================
133 ///
134 /// If the unit of the duration type is not one of the units specified above,
135 /// it is still possible to format it, provided you explicitly request a
136 /// display unit or you request that the unit is not displayed.
137
138 template <typename Rep, typename Period>
139 struct format_provider<std::chrono::duration<Rep, Period>> {
140 private:
141 typedef std::chrono::duration<Rep, Period> Dur;
142 typedef std::conditional_t<std::chrono::treat_as_floating_point<Rep>::value,
143 double, intmax_t>
144 InternalRep;
145
146 template <typename AsPeriod> static InternalRep getAs(const Dur &D) {
147 using namespace std::chrono;
148 return duration_cast<duration<InternalRep, AsPeriod>>(D).count();
149 }
150
151 static std::pair<InternalRep, StringRef> consumeUnit(StringRef &Style,
152 const Dur &D) {
153 using namespace std::chrono;
154 if (Style.consume_front("ns"))
155 return {getAs<std::nano>(D), "ns"};
156 if (Style.consume_front("us"))
157 return {getAs<std::micro>(D), "us"};
158 if (Style.consume_front("ms"))
159 return {getAs<std::milli>(D), "ms"};
160 if (Style.consume_front("s"))
161 return {getAs<std::ratio<1>>(D), "s"};
162 if (Style.consume_front("m"))
163 return {getAs<std::ratio<60>>(D), "m"};
164 if (Style.consume_front("h"))
165 return {getAs<std::ratio<3600>>(D), "h"};
166 return {D.count(), detail::unit<Period>::value};
167 }
168
169 static bool consumeShowUnit(StringRef &Style) {
170 if (Style.empty())
171 return true;
172 if (Style.consume_front("-"))
173 return false;
174 if (Style.consume_front("+"))
175 return true;
176 assert(0 && "Unrecognised duration format");
177 return true;
178 }
179
180 public:
181 static void format(const Dur &D, llvm::raw_ostream &Stream, StringRef Style) {
182 InternalRep count;
183 StringRef unit;
184 std::tie(count, unit) = consumeUnit(Style, D);
185 bool show_unit = consumeShowUnit(Style);
186
187 format_provider<InternalRep>::format(count, Stream, Style);
188
189 if (show_unit) {
190 assert(!unit.empty());
191 Stream << " " << unit;
192 }
193 }
194 };
195
196 } // namespace llvm
197
198 #endif // LLVM_SUPPORT_CHRONO_H
199