static CountedStopwatch TimeFor_ClassConstraint_NullCheck_HoistedCount <T>(T list)
where T : class, IList <string>
{
// just need something for the compiler to guarantee that list is not null.
if (list == null)
{
throw new ArgumentNullException();
}
var timer = new CountedStopwatch(TestName("Generic caller - for (class constraint, null check, hoisted count)", list.GetType(), typeof(T)));
for (int i = 0; i < TimedIntervals; i++)
{
timer.Start();
int count = list.Count;
for (int j = 0; j < count; j++)
{
var item = list[j];
DontElide(item);
}
timer.Stop();
}
return(timer);
}
static CountedStopwatch Time_Foreach_List(List <string> list)
{
var timer = new CountedStopwatch(TestName("foreach", list.GetType()));
for (int i = 0; i < TimedIntervals; i++)
{
timer.Start();
foreach (var item in list)
{
DontElide(item);
}
timer.Stop();
}
return(timer);
}
static CountedStopwatch TimeForeach_Dynamic(dynamic list)
{
var timer = new CountedStopwatch(TestName("foreach (dynamic)", list.GetType()));
for (int i = 0; i < TimedIntervals; i++)
{
timer.Start();
foreach (var item in list)
{
DontElide(item);
}
timer.Stop();
}
return(timer);
}
static CountedStopwatch Time_Foreach_YieldEnumerator(ReadOnlyCollectionYieldEnumerator <string> list)
{
var timer = new CountedStopwatch(TestName("foreach", list.GetType()));
for (int i = 0; i < TimedIntervals; i++)
{
timer.Start();
foreach (var item in list)
{
DontElide(item);
}
timer.Stop();
}
return(timer);
}
static CountedStopwatch Time_For_List(List <string> list)
{
var timer = new CountedStopwatch(TestName("for", list.GetType()));
for (int i = 0; i < TimedIntervals; i++)
{
timer.Start();
for (int j = 0; j < list.Count; j++)
{
var item = list[j];
DontElide(item);
}
timer.Stop();
}
return(timer);
}
static CountedStopwatch TimeForeach_ClassConstraint <T>(T list)
where T : class, IList <string>
{
var timer = new CountedStopwatch(TestName("Generic caller - foreach (class constraint)", list.GetType(), typeof(T)));
for (int i = 0; i < TimedIntervals; i++)
{
timer.Start();
foreach (var item in list)
{
DontElide(item);
}
timer.Stop();
}
return(timer);
}
static CountedStopwatch TimeFor <T>(T list)
where T : IList <string>
{
var timer = new CountedStopwatch(TestName("Generic caller - for", list.GetType(), typeof(T)));
for (int i = 0; i < TimedIntervals; i++)
{
timer.Start();
for (int j = 0; j < list.Count; j++)
{
var item = list[j];
DontElide(item);
}
timer.Stop();
}
return(timer);
}
static CountedStopwatch Time_For_IList_HoistedCount(IList <string> list)
{
var timer = new CountedStopwatch(TestName("for (Hoisted Count)", list.GetType(), typeof(IList <string>)));
for (int i = 0; i < TimedIntervals; i++)
{
timer.Start();
int count = list.Count;
for (int j = 0; j < count; j++)
{
var item = list[j];
DontElide(item);
}
timer.Stop();
}
return(timer);
}
static CountedStopwatch TimeFor_Dynamic(dynamic list)
{
var timer = new CountedStopwatch(TestName("for (dynamic)", list.GetType()));
for (int i = 0; i < TimedIntervals; i++)
{
timer.Start();
int count = list is Array ? list.Length : list.Count;
for (int j = 0; j < count; j++)
{
var item = list[j];
DontElide(item);
}
timer.Stop();
}
return(timer);
}
static void Main(string[] args)
{
// Data setup:
var list = new List <string>(capacity: CollectionSize);
for (int i = 0; i < list.Capacity; i++)
{
list.Add(NextString());
}
var array = list.ToArray();
var refList = new ReadOnlyCollectionRefEnumerator <string>(list);
var valList = new ReadOnlyCollectionValEnumerator <string>(list);
var yieldList = new ReadOnlyCollectionYieldEnumerator <string>(list);
// warm up QPC. I've noticed the first use can have a small delay, so
// make sure we don't get that while gathering measurements.
{
var warmup = new System.Diagnostics.Stopwatch();
warmup.Start();
warmup.Restart();
warmup.Restart();
}
// test cases:
Func <CountedStopwatch>[] tests =
{
// array tests:
() => Time_Foreach_Array(array),
() => Time_For_Array(array),
() => Time_Foreach_IList(array),
() => Time_For_IList(array),
// List<T> tests:
() => Time_Foreach_List(list),
() => Time_For_List(list),
() => Time_Foreach_IList(list),
() => Time_For_IList(list),
// Ref enumerator tests:
() => Time_Foreach_RefEnumerator(refList),
() => Time_For_RefEnumerator(refList),
() => Time_Foreach_IList(refList),
() => Time_For_IList(refList),
// Val enumerator tests:
() => Time_Foreach_ValEnumerator(valList),
() => Time_For_ValEnumerator(valList),
() => Time_Foreach_IList(valList),
() => Time_For_IList(valList),
// Yield enumerator tests:
() => Time_Foreach_YieldEnumerator(yieldList),
() => Time_For_YieldEnumerator(yieldList),
() => Time_Foreach_IList(yieldList),
() => Time_For_IList(yieldList),
#region Generic caller (IList<string> constraint)
// While trying to clean up the tests (less duplicate code and such) I made
// these generic TimeForeach and TimeFor functions. However, I found that
// they has *significantly* worse time-performance than the non-generic
// equivalents, and in turn, make for interesting, though unique, test cases.
//
// Later inspection revealed that the IL emitted for the generic methods has
// callvirt instructions to IList<string> members.
// array tests:
() => TimeForeach(array),
() => TimeFor(array),
// List<T> tests:
() => TimeForeach(list),
() => TimeFor(list),
// Ref enumerator tests:
() => TimeForeach(refList),
() => TimeFor(refList),
// Val enumerator tests:
() => TimeForeach(valList),
() => TimeFor(valList),
// Yield enumerator tests:
() => TimeForeach(yieldList),
() => TimeFor(yieldList),
#endregion
#region IList<string> Hoisted count
() => Time_For_IList_HoistedCount(array),
() => Time_For_IList_HoistedCount(list),
() => Time_For_IList_HoistedCount(refList),
() => Time_For_IList_HoistedCount(valList),
() => Time_For_IList_HoistedCount(yieldList),
#endregion
#region Trying to get generics to have better performance
() => TimeForeach_ClassConstraint(array),
() => TimeForeach_ClassConstraint_NullCheck(array),
() => TimeFor_ClassConstraint(array),
() => TimeFor_NullCheck(array),
() => TimeFor_HoistedCount(array),
() => TimeFor_ClassConstraint_NullCheck(array),
() => TimeFor_ClassConstraint_NullCheck_HoistedCount(array),
#endregion
#region Dynamic
() => TimeForeach_Dynamic(array),
() => TimeForeach_Dynamic(list),
() => TimeForeach_Dynamic(refList),
() => TimeForeach_Dynamic(valList),
() => TimeForeach_Dynamic(yieldList),
() => TimeFor_Dynamic(array),
() => TimeFor_Dynamic(list),
() => TimeFor_Dynamic(refList),
() => TimeFor_Dynamic(valList),
() => TimeFor_Dynamic(yieldList),
#endregion
};
// execution + output:
string sepLine = new string('=', 80);
foreach (var testCase in tests)
{
// try to avoid running anything GC-related while timing things.
GC.Collect();
GC.WaitForPendingFinalizers();
// run the test case
CountedStopwatch result = testCase();
// print the test result
Console.WriteLine(sepLine);
Console.WriteLine("Test: " + result.TestName);
Console.WriteLine();
Console.WriteLine("# Intervals: " + result.Intervals);
Console.WriteLine("Total Time: " + result.Elapsed.TotalMilliseconds + " ms");
Console.WriteLine("Average Time: " + result.AverageElapsed.TotalMilliseconds + " ms");
Console.WriteLine();
Console.WriteLine();
}
// pause if we are writing to the console
if (!Console.IsOutputRedirected)
{
Console.WriteLine("Press any key to continue . . .");
Console.ReadKey(intercept: true);
}
}