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CpuTimer.h
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// Copyright Contributors to the OpenVDB Project
// SPDX-License-Identifier: MPL-2.0
#ifndef OPENVDB_UTIL_CPUTIMER_HAS_BEEN_INCLUDED
#define OPENVDB_UTIL_CPUTIMER_HAS_BEEN_INCLUDED
#include <openvdb/version.h>
#include <string>
#include <chrono>
#include <iostream>// for std::cerr
#include <sstream>// for ostringstream
#include <iomanip>// for setprecision
#include "Formats.h"// for printTime
namespace openvdb {
OPENVDB_USE_VERSION_NAMESPACE
namespace OPENVDB_VERSION_NAME {
namespace util {
/// @brief Simple timer for basic profiling.
///
/// @code
/// util::CpuTimer timer;
/// // code here will not be timed!
/// timer.start("algorithm");
/// // code to be timed goes here
/// timer.stop();
/// @endcode
///
/// or to time multiple blocks of code
///
/// @code
/// util::CpuTimer timer("algorithm 1");
/// // code to be timed goes here
/// timer.restart("algorithm 2");
/// // code to be timed goes here
/// timer.stop();
/// @endcode
///
/// or to measure speedup between multiple runs
///
/// @code
/// util::CpuTimer timer("algorithm 1");
/// // code for the first run goes here
/// const double t1 = timer.restart("algorithm 2");
/// // code for the second run goes here
/// const double t2 = timer.stop();
/// std::cerr << "Algorithm 1 is " << (t2/t1)
/// << " timers faster than algorithm 2\n";
/// @endcode
///
/// or to measure multiple blocks of code with deferred output
///
/// @code
/// util::CpuTimer timer();
/// // code here will not be timed!
/// timer.start();
/// // code for the first run goes here
/// const double t1 = timer.restart();//time in milliseconds
/// // code for the second run goes here
/// const double t2 = timer.restart();//time in milliseconds
/// // code here will not be timed!
/// util::printTime(std::cout, t1, "Algorithm 1 completed in ");
/// util::printTime(std::cout, t2, "Algorithm 2 completed in ");
/// @endcode
class CpuTimer
{
public:
/// @brief Initiate timer
CpuTimer(std::ostream& os = std::cerr) : mOutStream(os), mT0(this->now()) {}
/// @brief Prints message and start timer.
///
/// @note Should normally be followed by a call to stop()
CpuTimer(const std::string& msg, std::ostream& os = std::cerr) : mOutStream(os) { this->start(msg); }
/// @brief Start timer.
///
/// @note Should normally be followed by a call to milliseconds() or stop(std::string)
inline void start() { mT0 = this->now(); }
/// @brief Print message and start timer.
///
/// @note Should normally be followed by a call to stop()
inline void start(const std::string& msg)
{
mOutStream << msg << " ...";
this->start();
}
/// @brief Return Time difference in microseconds since construction or start was called.
///
/// @note Combine this method with start() to get timing without any outputs.
inline int64_t microseconds() const
{
return (this->now() - mT0);
}
/// @brief Return Time difference in milliseconds since construction or start was called.
///
/// @note Combine this method with start() to get timing without any outputs.
inline double milliseconds() const
{
static constexpr double resolution = 1.0 / 1E3;
return static_cast<double>(this->microseconds()) * resolution;
}
/// @brief Return Time difference in seconds since construction or start was called.
///
/// @note Combine this method with start() to get timing without any outputs.
inline double seconds() const
{
static constexpr double resolution = 1.0 / 1E6;
return static_cast<double>(this->microseconds()) * resolution;
}
inline std::string time() const
{
const double msec = this->milliseconds();
std::ostringstream os;
printTime(os, msec, "", "", 4, 1, 1);
return os.str();
}
/// @brief Returns and prints time in milliseconds since construction or start was called.
///
/// @note Combine this method with start(std::string) to print at start and stop of task being timed.
inline double stop() const
{
const double msec = this->milliseconds();
printTime(mOutStream, msec, " completed in ", "\n", 4, 3, 1);
return msec;
}
/// @brief Returns and prints time in milliseconds since construction or start was called.
///
/// @note Combine this method with start() to delay output of task being timed.
inline double stop(const std::string& msg) const
{
const double msec = this->milliseconds();
mOutStream << msg << " ...";
printTime(mOutStream, msec, " completed in ", "\n", 4, 3, 1);
return msec;
}
/// @brief Re-start timer.
/// @return time in milliseconds since previous start or restart.
///
/// @note Should normally be followed by a call to stop() or restart()
inline double restart()
{
const double msec = this->milliseconds();
this->start();
return msec;
}
/// @brief Stop previous timer, print message and re-start timer.
/// @return time in milliseconds since previous start or restart.
///
/// @note Should normally be followed by a call to stop() or restart()
inline double restart(const std::string& msg)
{
const double delta = this->stop();
this->start(msg);
return delta;
}
private:
static int64_t now()
{
// steady_clock is a monotonically increasing clock designed for timing duration
// note that high_resolution_clock is aliased to either steady_clock or system_clock
// depending on the platform, so it is preferrable to use steady_clock
const auto time_since_epoch =
std::chrono::steady_clock::now().time_since_epoch();
// cast time since epoch into microseconds (1 / 1000000 seconds)
const auto microseconds =
std::chrono::duration_cast<std::chrono::microseconds>(time_since_epoch).count();
// cast to a a 64-bit signed integer as this will overflow in 2262!
return static_cast<int64_t>(microseconds);
}
std::ostream& mOutStream;
int64_t mT0{0};
};// CpuTimer
} // namespace util
} // namespace OPENVDB_VERSION_NAME
} // namespace openvdb
#endif // OPENVDB_UTIL_CPUTIMER_HAS_BEEN_INCLUDED
Formats.h
Utility routines to output nicely-formatted numeric values.
openvdb::v10_0::util::CpuTimer::seconds
double seconds() const
Return Time difference in seconds since construction or start was called.
Definition CpuTimer.h:111
openvdb::v10_0::util::CpuTimer::milliseconds
double milliseconds() const
Return Time difference in milliseconds since construction or start was called.
Definition CpuTimer.h:102
openvdb::v10_0::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_0::util::CpuTimer::start
void start()
Start timer.
Definition CpuTimer.h:80
openvdb::v10_0::util::CpuTimer::start
void start(const std::string &msg)
Print message and start timer.
Definition CpuTimer.h:85
openvdb::v10_0::util::CpuTimer::time
std::string time() const
Definition CpuTimer.h:117
openvdb::v10_0::util::CpuTimer::CpuTimer
CpuTimer(const std::string &msg, std::ostream &os=std::cerr)
Prints message and start timer.
Definition CpuTimer.h:75
openvdb::v10_0::util::CpuTimer::stop
double stop() const
Returns and prints time in milliseconds since construction or start was called.
Definition CpuTimer.h:128
openvdb::v10_0::util::CpuTimer::restart
double restart(const std::string &msg)
Stop previous timer, print message and re-start timer.
Definition CpuTimer.h:161
openvdb::v10_0::util::CpuTimer::microseconds
int64_t microseconds() const
Return Time difference in microseconds since construction or start was called.
Definition CpuTimer.h:94
openvdb::v10_0::util::CpuTimer::CpuTimer
CpuTimer(std::ostream &os=std::cerr)
Initiate timer.
Definition CpuTimer.h:70
openvdb::v10_0::util::CpuTimer::restart
double restart()
Re-start timer.
Definition CpuTimer.h:150
openvdb::v10_0::util
Definition CpuTimer.h:18
openvdb::v10_0::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