|
Flow123d
DF_patch_fe_data_tables-b669755
|
#include <time_point.hh>
Public Member Functions | |
| TimePoint () | |
| double | operator- (const TimePoint &right) |
Public Attributes | |
| long long | ticks |
Class TimerData serves for getting current time in ticks units. TimerData overloads standard + and - operators so object can be subtracted/added from/to one another.
TimerData uses one if the following timers based on set definition namely:
1) FLOW123D_HAVE_TIMER_QUERY_PERFORMANCE_COUNTER It is used Timer for Windows platform only.
Method QueryPerformanceCounter populates given LARGE_INTEGER object with timer informations. Resolution if this timer is several hundreds ns. Tests have shown average about 300 ns. Maximum resolution is 1 ns.
2) FLOW123D_HAVE_TIMER_CHRONO_HIGH_RESOLUTION (default without definition set) It is used standard multiplatform Chrono Timer which is available since C++11 (compile flag -std=cxx11 required!)
Resolution of timer depends on HW but tests shown results fluctuating around 1000 ns. Maximum resolution is 1 ns.
Note: Standard clock() method available in c++ yields resolution in units of milliseconds (roughly 10 ms) but some compilers replaces during compilation method clock() with better Timer having resolution 1000 ns. Meaning clock() method is not sufficient or stable for time measurements. Maximum resolution is 1000 ns (limited by value of CLOCKS_PER_SEC).
gettimeofday The actual resolution of gettimeofday() depends on the hardware architecture. Intel processors as well as SPARC machines offer high resolution timers that measure microseconds. Other hardware architectures fall back to the system’s timer, which is typically set to 100 Hz. In such cases, the time resolution will be less accurate. gettimeofday() can result in incorrect timings if there are processes on your system that change the timer Possible solution may be other clock
clock_gettime (CLOCK_MONOTONIC) with clock_getres() method but clock_gettime is present only on newest Linux. other system have only gettimeofday()
Definition at line 69 of file time_point.hh.
| TimePoint::TimePoint | ( | ) |
Constructor will populate object with current time
Definition at line 71 of file time_point.cc.
| double TimePoint::operator- | ( | const TimePoint & | right | ) |
Overloaded operator for subtraction. Allows subtracting TimerPoint objects using '-' sign Used for determining interval between two TimerPoints
Returns duration in seconds
Definition at line 77 of file time_point.cc.
| long long TimePoint::ticks |
Internal variable for storing actual ticks
Definition at line 88 of file time_point.hh.
1.9.1