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 LLVM_ABI raw_ostream &operator<<(raw_ostream &OS, sys::TimePoint<> TP);
81 LLVM_ABI 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 LLVM_ABI 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 LLVM_ABI 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>> {
107 LLVM_ABI static const char value[];
108 };
109 template <> struct unit<std::ratio<60>> {
110 LLVM_ABI static const char value[];
111 };
112 template <> struct unit<std::ratio<1>> {
113 LLVM_ABI static const char value[];
114 };
115 template <> struct unit<std::milli> {
116 LLVM_ABI static const char value[];
117 };
118 template <> struct unit<std::micro> {
119 LLVM_ABI static const char value[];
120 };
121 template <> struct unit<std::nano> {
122 LLVM_ABI static const char value[];
123 };
124 } // namespace detail
125
126 /// Implementation of format_provider<T> for duration types.
127 ///
128 /// The options string of a duration type has the grammar:
129 ///
130 /// duration_options ::= [unit][show_unit [number_options]]
131 /// unit ::= `h`|`m`|`s`|`ms|`us`|`ns`
132 /// show_unit ::= `+` | `-`
133 /// number_options ::= options string for a integral or floating point type
134 ///
135 /// Examples
136 /// =================================
137 /// | options | Input | Output |
138 /// =================================
139 /// | "" | 1s | 1 s |
140 /// | "ms" | 1s | 1000 ms |
141 /// | "ms-" | 1s | 1000 |
142 /// | "ms-n" | 1s | 1,000 |
143 /// | "" | 1.0s | 1.00 s |
144 /// =================================
145 ///
146 /// If the unit of the duration type is not one of the units specified above,
147 /// it is still possible to format it, provided you explicitly request a
148 /// display unit or you request that the unit is not displayed.
149
150 template <typename Rep, typename Period>
151 struct format_provider<std::chrono::duration<Rep, Period>> {
152 private:
153 typedef std::chrono::duration<Rep, Period> Dur;
154 typedef std::conditional_t<std::chrono::treat_as_floating_point<Rep>::value,
155 double, intmax_t>
156 InternalRep;
157
158 template <typename AsPeriod> static InternalRep getAs(const Dur &D) {
159 using namespace std::chrono;
160 return duration_cast<duration<InternalRep, AsPeriod>>(D).count();
161 }
162
163 static std::pair<InternalRep, StringRef> consumeUnit(StringRef &Style,
164 const Dur &D) {
165 using namespace std::chrono;
166 if (Style.consume_front("ns"))
167 return {getAs<std::nano>(D), "ns"};
168 if (Style.consume_front("us"))
169 return {getAs<std::micro>(D), "us"};
170 if (Style.consume_front("ms"))
171 return {getAs<std::milli>(D), "ms"};
172 if (Style.consume_front("s"))
173 return {getAs<std::ratio<1>>(D), "s"};
174 if (Style.consume_front("m"))
175 return {getAs<std::ratio<60>>(D), "m"};
176 if (Style.consume_front("h"))
177 return {getAs<std::ratio<3600>>(D), "h"};
178 return {D.count(), detail::unit<Period>::value};
179 }
180
181 static bool consumeShowUnit(StringRef &Style) {
182 if (Style.empty())
183 return true;
184 if (Style.consume_front("-"))
185 return false;
186 if (Style.consume_front("+"))
187 return true;
188 assert(0 && "Unrecognised duration format");
189 return true;
190 }
191
192 public:
193 static void format(const Dur &D, llvm::raw_ostream &Stream, StringRef Style) {
194 InternalRep count;
195 StringRef unit;
196 std::tie(count, unit) = consumeUnit(Style, D);
197 bool show_unit = consumeShowUnit(Style);
198
199 format_provider<InternalRep>::format(count, Stream, Style);
200
201 if (show_unit) {
202 assert(!unit.empty());
203 Stream << " " << unit;
204 }
205 }
206 };
207
208 } // namespace llvm
209
210 #endif // LLVM_SUPPORT_CHRONO_H
211