I just did some benchmarks using the new C# 6 null conditional operator ?.
Consider the following scenario: class A
has a child class B
, which has a child C
, whose Name
property we want to flatten into a DTO. I tested two variants:
// using mapfrom
CreateMap<MapFromA, MapFromADto>()
.ForMember(dto => dto.Name, o => o.MapFrom(a => a.B.C.Name));
// using resolveusing with elvis
CreateMap<ResolveUsingX, ResolveUsingXDto>()
.ForMember(dto => dto.Name, o => o.ResolveUsing(x => x.Y?.Z?.Name));
I called _mapper.Map<ResolveUsingXDto>(x);
or _mapper.Map<MapFromADto>(a);
for 1000 different ResolveUsingX x
and MapFromA a
and took the time using a System.Diagnostics.StopWatch
. Here are my results:
Distinct elements per batch: 1000; # batches for average: 25
A->B->C.Name, C is never null.
MapForm - average time taken for 1000x: 5527,84 ticks = 1,44 ms.
ResolveUsing - average time taken for 1000x: 5479,76 ticks = 1,4 ms.
A->B->C.Name, C is null 1/3 of the time.
MapForm - average time taken for 1000x: 72924,4 ticks = 27,44 ms.
ResolveUsing - average time taken for 1000x: 5351,2 ticks = 1,48 ms.
A->B->C.Name, C is null 1/2 of the time.
MapForm - average time taken for 1000x: 107016,92 ticks = 40,52 ms.
ResolveUsing - average time taken for 1000x: 5835,32 ticks = 1,56 ms.
A->B->C.Name, C is null 2/3 of the time.
MapForm - average time taken for 1000x: 141437,96 ticks = 53,64 ms.
ResolveUsing - average time taken for 1000x: 5789,72 ticks = 1,56 ms.
MapFrom
has to catch NullReferenceExceptions, which is slower than ResolveUsing
with the elvis operator ?.