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