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Struct `std.datetime.StopWatch`

The old benchmarking functionality in std.datetime (which uses TickDuration) has been deprecated. Use what's in std.datetime.stopwatch instead. It uses MonoTime and Duration. See StopWatch. This symbol will be removed from the documentation in October 2018 and fully removed from Phobos in October 2019.


						
				struct StopWatch
				;

StopWatch measures time as precisely as possible.

This class uses a high-performance counter. On Windows systems, it uses QueryPerformanceCounter, and on Posix systems, it uses clock_gettime if available, and gettimeofday otherwise.

But the precision of StopWatch differs from system to system. It is impossible to for it to be the same from system to system since the precision of the system clock varies from system to system, and other system-dependent and situation-dependent stuff (such as the overhead of a context switch between threads) can also affect StopWatch's accuracy.

Constructors

Name	Description
`this`	Auto start with constructor.

Properties

Name	Type	Description
`running`[get]	`bool`	Confirm whether this stopwatch is measuring time.

Methods

Name	Description
`opEquals`
`peek`	Peek at the amount of time which has passed since the stop watch was started.
`reset`	Resets the stop watch.
`setMeasured`	Set the amount of time which has been measured since the stop watch was started.
`start`	Starts the stop watch.
`stop`	Stops the stop watch.

Example

void writeln(S...)(S args){}
static void bar() {}

StopWatch sw;
enum n = 100;
TickDuration[n] times;
TickDuration last = TickDuration.from!"seconds"(0);
foreach (i; 0 .. n)
{
   sw.start(); //start/resume mesuring.
   foreach (unused; 0 .. 1_000_000)
       bar();
   sw.stop();  //stop/pause measuring.
   //Return value of peek() after having stopped are the always same.
   writeln((i + 1) * 1_000_000, " times done, lap time: ",
           sw.peek().msecs, "[ms]");
   times[i] = sw.peek() - last;
   last = sw.peek();
}
real sum = 0;
// To get the number of seconds,
// use properties of TickDuration.
// (seconds, msecs, usecs, hnsecs)
foreach (t; times)
   sum += t.hnsecs;
writeln("Average time: ", sum/n, " hnsecs");

Authors

Jonathan M Davis and Kato Shoichi

License

Boost License 1.0.