Improve on Union performance (#176)

Preallocating the HashSet allows for less CPU and memory usage then using Linq.Union.
Unleash · Nov 22, 2023 · b51b051 · b51b051
1 parent 3378109
commit b51b051
Showing 1 changed file with 6 additions and 5 deletions.
diff --git a/src/Unleash/DefaultUnleash.cs b/src/Unleash/DefaultUnleash.cs
@@ -156,11 +156,12 @@ private bool DetermineIsEnabledAndStrategy(
             }
             else
             {
-                strategy = featureToggle.Strategies
-                    .FirstOrDefault(s =>
-                        GetStrategyOrUnknown(s.Name)
-                        .IsEnabled(s.Parameters, enhancedContext, ResolveConstraints(s).Union(s.Constraints))
-                    );
+                strategy = featureToggle.Strategies.FirstOrDefault(s =>
+                {
+                    var uniqueConstraints = new HashSet<Constraint>(ResolveConstraints(s));
+                    uniqueConstraints.UnionWith(s.Constraints);
+                    return GetStrategyOrUnknown(s.Name).IsEnabled(s.Parameters, enhancedContext, uniqueConstraints);
+                });
             }
 
             if (featureToggle.Dependencies.Any() && !ParentDependenciesAreSatisfied(featureToggle, enhancedContext))