org.sonar.plugins.csharp.S6603.html Maven / Gradle / Ivy
Why is this an issue?
Both the List.TrueForAll method and the IEnumerable.All method can be used to check if all list elements satisfy a given
condition in a collection. However, List.TrueForAll can be faster than IEnumerable.All for List objects. The
performance difference may be minor for small collections, but for large collections, it can be noticeable.
Applies to
What is the potential impact?
We measured at least 4x improvement both in execution time. For more details see the Benchmarks section from the More
info tab.
How to fix it
The TrueForAll method is defined on the collection class, and it has the same signature as the All extension method. The
method can be replaced in place.
Code examples
Noncompliant code example
public bool AreAllEven(List<int> data) =>
data.All(x => x % 2 == 0);
public bool AreAllEven(int[] data) =>
data.All(x => x % 2 == 0);
Compliant solution
public bool AreAllEven(List<int> data) =>
data.TrueForAll(x => x % 2 == 0);
public bool AreAllEven(int[] data) =>
Array.TrueForAll(data, x => x % 2 == 0);
Resources
Documentation
- List<T>.TrueForAll(Predicate<T>)
- Array.TrueForAll<T>(T[], Predicate<T>)
- ImmutableList<T>.TrueForAll(Predicate<T>)
- ImmutableList<T>.Builder.TrueForAll(Predicate<T>)
- Enumerable.All<TSource>
Benchmarks
Method
Runtime
Mean
Standard Deviation
Allocated
TrueForAll
.NET 7.0
1.302 ms
0.0027 ms
1 B
All
.NET 7.0
6.279 ms
0.0181 ms
40004 B
TrueForAll
.NET Framework 4.6.2
1.105 ms
0.0142 ms
-
All
.NET Framework 4.6.2
4.968 ms
0.0143 ms
40128 B
Glossary
The results were generated by running the following snippet with BenchmarkDotNet:
private List<int> data;
[Params(10_000)]
public int N { get; set; }
[GlobalSetup]
public void Setup() =>
data = Enumerable.Range(0, N).Select(x => 42).ToList();
[Benchmark]
public void TrueForAll()
{
for (var i = 0; i < N; i++)
{
_ = data.TrueForAll(x => x == 42); // List<T>.TrueForAll
}
}
[Benchmark(Baseline = true)]
public void All()
{
for (var i = 0; i < N; i++)
{
_ = data.All(x => x == 42); // Enumerable.All<TSource>
}
}
Hardware configuration:
BenchmarkDotNet=v0.13.5, OS=Windows 10 (10.0.19045.2846/22H2/2022Update)
12th Gen Intel Core i7-12800H, 1 CPU, 20 logical and 14 physical cores
.NET SDK=7.0.203
[Host] : .NET 7.0.5 (7.0.523.17405), X64 RyuJIT AVX2
.NET 7.0 : .NET 7.0.5 (7.0.523.17405), X64 RyuJIT AVX2
.NET Framework 4.6.2 : .NET Framework 4.8 (4.8.4614.0), X64 RyuJIT VectorSize=256