1//===- llvm/Support/Chrono.h - Utilities for Timing Manipulation-*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9
10#ifndef LLVM_SUPPORT_CHRONO_H
11#define LLVM_SUPPORT_CHRONO_H
12
13#include "llvm/Support/Compiler.h"
14#include "llvm/Support/FormatProviders.h"
15
16#include <chrono>
17#include <ctime>
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 agains subtle differences in behavoir to differences in
27///   system clock precision (which is implementation-defined and differs between
28///   platforms).
29/// - to shorten the type name
30/// The default precision is nanoseconds. If need a specific precision specify
31/// it explicitly. If unsure, use the default. If you need a time point on a
32/// 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
37LLVM_ATTRIBUTE_ALWAYS_INLINE inline std::time_t toTimeT(TimePoint<> TP) {
38  using namespace std::chrono;
39  return system_clock::to_time_t(
40      time_point_cast<system_clock::time_point::duration>(TP));
41}
42
43/// Convert a std::time_t to a TimePoint
44LLVM_ATTRIBUTE_ALWAYS_INLINE inline TimePoint<std::chrono::seconds>
45toTimePoint(std::time_t T) {
46  using namespace std::chrono;
47  return time_point_cast<seconds>(system_clock::from_time_t(T));
48}
49
50} // namespace sys
51
52raw_ostream &operator<<(raw_ostream &OS, sys::TimePoint<> TP);
53
54/// Implementation of format_provider<T> for duration types.
55///
56/// The options string of a duration  type has the grammar:
57///
58///   duration_options  ::= [unit][show_unit [number_options]]
59///   unit              ::= `h`|`m`|`s`|`ms|`us`|`ns`
60///   show_unit         ::= `+` | `-`
61///   number_options    ::= options string for a integral or floating point type
62///
63///   Examples
64///   =================================
65///   |  options  | Input | Output    |
66///   =================================
67///   | ""        | 1s    | 1 s       |
68///   | "ms"      | 1s    | 1000 ms   |
69///   | "ms-"     | 1s    | 1000      |
70///   | "ms-n"    | 1s    | 1,000     |
71///   | ""        | 1.0s  | 1.00 s    |
72///   =================================
73///
74///  If the unit of the duration type is not one of the units specified above,
75///  it is still possible to format it, provided you explicitly request a
76///  display unit or you request that the unit is not displayed.
77
78namespace detail {
79template <typename Period> struct unit { static const char value[]; };
80template <typename Period> const char unit<Period>::value[] = "";
81
82template <> struct unit<std::ratio<3600>> { static const char value[]; };
83template <> struct unit<std::ratio<60>> { static const char value[]; };
84template <> struct unit<std::ratio<1>> { static const char value[]; };
85template <> struct unit<std::milli> { static const char value[]; };
86template <> struct unit<std::micro> { static const char value[]; };
87template <> struct unit<std::nano> { static const char value[]; };
88} // namespace detail
89
90template <typename Rep, typename Period>
91struct format_provider<std::chrono::duration<Rep, Period>> {
92private:
93  typedef std::chrono::duration<Rep, Period> Dur;
94  typedef typename std::conditional<
95      std::chrono::treat_as_floating_point<Rep>::value, double, intmax_t>::type
96      InternalRep;
97
98  template <typename AsPeriod> static InternalRep getAs(const Dur &D) {
99    using namespace std::chrono;
100    return duration_cast<duration<InternalRep, AsPeriod>>(D).count();
101  }
102
103  static std::pair<InternalRep, StringRef> consumeUnit(StringRef &Style,
104                                                        const Dur &D) {
105    using namespace std::chrono;
106    if (Style.consume_front("ns"))
107      return {getAs<std::nano>(D), "ns"};
108    if (Style.consume_front("us"))
109      return {getAs<std::micro>(D), "us"};
110    if (Style.consume_front("ms"))
111      return {getAs<std::milli>(D), "ms"};
112    if (Style.consume_front("s"))
113      return {getAs<std::ratio<1>>(D), "s"};
114    if (Style.consume_front("m"))
115      return {getAs<std::ratio<60>>(D), "m"};
116    if (Style.consume_front("h"))
117      return {getAs<std::ratio<3600>>(D), "h"};
118    return {D.count(), detail::unit<Period>::value};
119  }
120
121  static bool consumeShowUnit(StringRef &Style) {
122    if (Style.empty())
123      return true;
124    if (Style.consume_front("-"))
125      return false;
126    if (Style.consume_front("+"))
127      return true;
128    assert(0 && "Unrecognised duration format");
129    return true;
130  }
131
132public:
133  static void format(const Dur &D, llvm::raw_ostream &Stream, StringRef Style) {
134    InternalRep count;
135    StringRef unit;
136    std::tie(count, unit) = consumeUnit(Style, D);
137    bool show_unit = consumeShowUnit(Style);
138
139    format_provider<InternalRep>::format(count, Stream, Style);
140
141    if (show_unit) {
142      assert(!unit.empty());
143      Stream << " " << unit;
144    }
145  }
146};
147
148} // namespace llvm
149
150#endif // LLVM_SUPPORT_CHRONO_H
151