OpenVDB: openvdb/util/CpuTimer.h Source File

OpenVDB 10.1.0

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CpuTimer.h
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1// Copyright Contributors to the OpenVDB Project
2// SPDX-License-Identifier: MPL-2.0
3
4#ifndef OPENVDB_UTIL_CPUTIMER_HAS_BEEN_INCLUDED
5#define OPENVDB_UTIL_CPUTIMER_HAS_BEEN_INCLUDED
6
7#include <openvdb/version.h>
8#include <string>
9#include <chrono>
10#include <iostream>// for std::cerr
11#include <sstream>// for ostringstream
12#include <iomanip>// for setprecision
13#include "Formats.h"// for printTime
14
15namespace openvdb {
16 OPENVDB_USE_VERSION_NAMESPACE
17namespace OPENVDB_VERSION_NAME {
18 namespace util {
19
20/// @brief Simple timer for basic profiling.
21///
22/// @code
23/// util::CpuTimer timer;
24/// // code here will not be timed!
25/// timer.start("algorithm");
26/// // code to be timed goes here
27/// timer.stop();
28/// @endcode
29///
30/// or to time multiple blocks of code
31///
32/// @code
33/// util::CpuTimer timer("algorithm 1");
34/// // code to be timed goes here
35/// timer.restart("algorithm 2");
36/// // code to be timed goes here
37/// timer.stop();
38/// @endcode
39///
40/// or to measure speedup between multiple runs
41///
42/// @code
43/// util::CpuTimer timer("algorithm 1");
44/// // code for the first run goes here
45/// const double t1 = timer.restart("algorithm 2");
46/// // code for the second run goes here
47/// const double t2 = timer.stop();
48/// std::cerr << "Algorithm 1 is " << (t2/t1)
49/// << " timers faster than algorithm 2\n";
50/// @endcode
51///
52/// or to measure multiple blocks of code with deferred output
53///
54/// @code
55/// util::CpuTimer timer();
56/// // code here will not be timed!
57/// timer.start();
58/// // code for the first run goes here
59/// const double t1 = timer.restart();//time in milliseconds
60/// // code for the second run goes here
61/// const double t2 = timer.restart();//time in milliseconds
62/// // code here will not be timed!
63/// util::printTime(std::cout, t1, "Algorithm 1 completed in ");
64/// util::printTime(std::cout, t2, "Algorithm 2 completed in ");
65/// @endcode
66 class CpuTimer
67{
68public:
69 /// @brief Initiate timer
70 CpuTimer(std::ostream& os = std::cerr) : mOutStream(os), mT0(this->now()) {}
71
72 /// @brief Prints message and start timer.
73 ///
74 /// @note Should normally be followed by a call to stop()
75 CpuTimer(const std::string& msg, std::ostream& os = std::cerr) : mOutStream(os) { this->start(msg); }
76
77 /// @brief Start timer.
78 ///
79 /// @note Should normally be followed by a call to milliseconds() or stop(std::string)
80 inline void start() { mT0 = this->now(); }
81
82 /// @brief Print message and start timer.
83 ///
84 /// @note Should normally be followed by a call to stop()
85 inline void start(const std::string& msg)
86 {
87 mOutStream << msg << " ...";
88 this->start();
89 }
90
91 /// @brief Return Time difference in microseconds since construction or start was called.
92 ///
93 /// @note Combine this method with start() to get timing without any outputs.
94 inline int64_t microseconds() const
95 {
96 return (this->now() - mT0);
97 }
98
99 /// @brief Return Time difference in milliseconds since construction or start was called.
100 ///
101 /// @note Combine this method with start() to get timing without any outputs.
102 inline double milliseconds() const
103 {
104 static constexpr double resolution = 1.0 / 1E3;
105 return static_cast<double>(this->microseconds()) * resolution;
106 }
107
108 /// @brief Return Time difference in seconds since construction or start was called.
109 ///
110 /// @note Combine this method with start() to get timing without any outputs.
111 inline double seconds() const
112 {
113 static constexpr double resolution = 1.0 / 1E6;
114 return static_cast<double>(this->microseconds()) * resolution;
115 }
116
117 inline std::string time() const
118 {
119 const double msec = this->milliseconds();
120 std::ostringstream os;
121 printTime(os, msec, "", "", 4, 1, 1);
122 return os.str();
123 }
124
125 /// @brief Returns and prints time in milliseconds since construction or start was called.
126 ///
127 /// @note Combine this method with start(std::string) to print at start and stop of task being timed.
128 inline double stop() const
129 {
130 const double msec = this->milliseconds();
131 printTime(mOutStream, msec, " completed in ", "\n", 4, 3, 1);
132 return msec;
133 }
134
135 /// @brief Returns and prints time in milliseconds since construction or start was called.
136 ///
137 /// @note Combine this method with start() to delay output of task being timed.
138 inline double stop(const std::string& msg) const
139 {
140 const double msec = this->milliseconds();
141 mOutStream << msg << " ...";
142 printTime(mOutStream, msec, " completed in ", "\n", 4, 3, 1);
143 return msec;
144 }
145
146 /// @brief Re-start timer.
147 /// @return time in milliseconds since previous start or restart.
148 ///
149 /// @note Should normally be followed by a call to stop() or restart()
150 inline double restart()
151 {
152 const double msec = this->milliseconds();
153 this->start();
154 return msec;
155 }
156
157 /// @brief Stop previous timer, print message and re-start timer.
158 /// @return time in milliseconds since previous start or restart.
159 ///
160 /// @note Should normally be followed by a call to stop() or restart()
161 inline double restart(const std::string& msg)
162 {
163 const double delta = this->stop();
164 this->start(msg);
165 return delta;
166 }
167
168private:
169 static int64_t now()
170 {
171 // steady_clock is a monotonically increasing clock designed for timing duration
172 // note that high_resolution_clock is aliased to either steady_clock or system_clock
173 // depending on the platform, so it is preferrable to use steady_clock
174 const auto time_since_epoch =
175 std::chrono::steady_clock::now().time_since_epoch();
176 // cast time since epoch into microseconds (1 / 1000000 seconds)
177 const auto microseconds =
178 std::chrono::duration_cast<std::chrono::microseconds>(time_since_epoch).count();
179 // cast to a a 64-bit signed integer as this will overflow in 2262!
180 return static_cast<int64_t>(microseconds);
181 }
182
183 std::ostream& mOutStream;
184 int64_t mT0{0};
185};// CpuTimer
186
187} // namespace util
188} // namespace OPENVDB_VERSION_NAME
189} // namespace openvdb
190
191
192#endif // OPENVDB_UTIL_CPUTIMER_HAS_BEEN_INCLUDED
Formats.h
Utility routines to output nicely-formatted numeric values.
openvdb::v10_1::util::CpuTimer
Simple timer for basic profiling.
Definition CpuTimer.h:67
openvdb::v10_1::util::CpuTimer::seconds
double seconds() const
Return Time difference in seconds since construction or start was called.
Definition CpuTimer.h:111
openvdb::v10_1::util::CpuTimer::milliseconds
double milliseconds() const
Return Time difference in milliseconds since construction or start was called.
Definition CpuTimer.h:102
openvdb::v10_1::util::CpuTimer::stop
double stop(const std::string &msg) const
Returns and prints time in milliseconds since construction or start was called.
Definition CpuTimer.h:138
openvdb::v10_1::util::CpuTimer::start
void start()
Start timer.
Definition CpuTimer.h:80
openvdb::v10_1::util::CpuTimer::start
void start(const std::string &msg)
Print message and start timer.
Definition CpuTimer.h:85
openvdb::v10_1::util::CpuTimer::time
std::string time() const
Definition CpuTimer.h:117
openvdb::v10_1::util::CpuTimer::CpuTimer
CpuTimer(const std::string &msg, std::ostream &os=std::cerr)
Prints message and start timer.
Definition CpuTimer.h:75
openvdb::v10_1::util::CpuTimer::stop
double stop() const
Returns and prints time in milliseconds since construction or start was called.
Definition CpuTimer.h:128
openvdb::v10_1::util::CpuTimer::restart
double restart(const std::string &msg)
Stop previous timer, print message and re-start timer.
Definition CpuTimer.h:161
openvdb::v10_1::util::CpuTimer::microseconds
int64_t microseconds() const
Return Time difference in microseconds since construction or start was called.
Definition CpuTimer.h:94
openvdb::v10_1::util::CpuTimer::CpuTimer
CpuTimer(std::ostream &os=std::cerr)
Initiate timer.
Definition CpuTimer.h:70
openvdb::v10_1::util::CpuTimer::restart
double restart()
Re-start timer.
Definition CpuTimer.h:150
openvdb::v10_1::util::printTime
OPENVDB_API int printTime(std::ostream &os, double milliseconds, const std::string &head="", const std::string &tail="\n", int width=4, int precision=1, int verbose=0)
openvdb
Definition Exceptions.h:13
OPENVDB_VERSION_NAME
#define OPENVDB_VERSION_NAME
The version namespace name for this library version.
Definition version.h.in:121
OPENVDB_USE_VERSION_NAMESPACE
#define OPENVDB_USE_VERSION_NAMESPACE
Definition version.h.in:212