On Saturday, 13 February 2016 at 19:24:44 UTC, ishwar wrote:
I am stumped on need finding interval between two events in a
program execution in nanoseconds. Any sample code will be
appreciated (along with imports needed to make it work):
- time in nanoseconds-now
- do-some processing
- time in nano-second-now
Thanks
As suggested above, use a StopWatch.
I use this (not-very-cross-platform) function for latency
measurement purposes. It is precise on Linux. For Mac OS and
Windows, it's returns an approximation:
version(linux) import core.sys.linux.time;
version(OSX) import core.time;
version(Windows) import core.sys.windows.windows;
static if(is(typeof(clockid_t)))
{
extern(C) nothrow int clock_gettime(clockid_t, timespec*);
}
public ulong getLocalTimestampNS() nothrow @nogc
{
static if(is(typeof(clock_gettime)))
{
timespec ts;
clock_gettime(CLOCK_MONOTONIC_RAW, &ts);
return ts.tv_sec * 1000000000 + ts.tv_nsec;
}
static if(is(typeof(mach_absolute_time)))
{
// IMPORTANT NOTE: mach_absolute_time does not always
return nanoseconds.
// Sometimes it returns other values. We are using it
here as an approximation.
return mach_absolute_time();
}
version (Windows)
{
// Just an approximation
long cnt;
if (QueryPerformanceCounter(&cnt))
{
return cnt * 500;
}
return 0;
}
}
