Use TryGetValue for dictionary lookups in OpenAPI comparers (#57208)

* Use TryGetValue for dictionary lookups

Use `TryGetValue()` to avoid multiple dictionary lookups in OpenAPI schema comparers.

* Re-order equality comparer checks

See #57208 (comment).

* Check discriminators earlier

Check discriminators earlier too.

Author: martincostello

src/OpenApi/src/Comparers/OpenApiAnyComparer.cs

@@ -30,7 +30,7 @@ public bool Equals(IOpenApiAny? x, IOpenApiAny? y)
             {
                 OpenApiNull _ => y is OpenApiNull,
                 OpenApiArray arrayX => y is OpenApiArray arrayY && arrayX.SequenceEqual(arrayY, Instance),
-                OpenApiObject objectX => y is OpenApiObject objectY && objectX.Keys.Count == objectY.Keys.Count && objectX.Keys.All(key => objectY.ContainsKey(key) && Equals(objectX[key], objectY[key])),
+                OpenApiObject objectX => y is OpenApiObject objectY && objectX.Keys.Count == objectY.Keys.Count && objectX.Keys.All(key => objectY.TryGetValue(key, out var yValue) && Equals(objectX[key], yValue)),
                 OpenApiBinary binaryX => y is OpenApiBinary binaryY && binaryX.Value.SequenceEqual(binaryY.Value),
                 OpenApiInteger integerX => y is OpenApiInteger integerY && integerX.Value == integerY.Value,
                 OpenApiLong longX => y is OpenApiLong longY && longX.Value == longY.Value,

src/OpenApi/src/Comparers/OpenApiDiscriminatorComparer.cs

@@ -27,7 +27,7 @@ public bool Equals(OpenApiDiscriminator? x, OpenApiDiscriminator? y)
 
         return x.PropertyName == y.PropertyName &&
             x.Mapping.Count == y.Mapping.Count &&
-            x.Mapping.Keys.All(key => y.Mapping.ContainsKey(key) && x.Mapping[key] == y.Mapping[key]);
+            x.Mapping.Keys.All(key => y.Mapping.TryGetValue(key, out var yValue) && x.Mapping[key] == yValue);
     }
 
     public int GetHashCode(OpenApiDiscriminator obj)

src/OpenApi/src/Comparers/OpenApiExternalDocsComparer.cs

@@ -28,7 +28,7 @@ public bool Equals(OpenApiExternalDocs? x, OpenApiExternalDocs? y)
         return x.Description == y.Description &&
             x.Url == y.Url &&
             x.Extensions.Count == y.Extensions.Count
-            && x.Extensions.Keys.All(k => y.Extensions.ContainsKey(k) && y.Extensions[k] == x.Extensions[k]);
+            && x.Extensions.Keys.All(k => y.Extensions.TryGetValue(k, out var yValue) && yValue == x.Extensions[k]);
     }
 
     public int GetHashCode(OpenApiExternalDocs obj)

src/OpenApi/src/Comparers/OpenApiSchemaComparer.cs

@@ -26,25 +26,29 @@ public bool Equals(OpenApiSchema? x, OpenApiSchema? y)
             return true;
         }
 
-        return Instance.Equals(x.AdditionalProperties, y.AdditionalProperties) &&
+        // Compare property equality in an order that should help us find inequality faster
+        return
+            x.Type == y.Type &&
+            x.Format == y.Format &&
+            SchemaIdEquals(x, y) &&
+            x.Properties.Keys.All(k => y.Properties.TryGetValue(k, out var yValue) && Instance.Equals(x.Properties[k], yValue)) &&
+            OpenApiDiscriminatorComparer.Instance.Equals(x.Discriminator, y.Discriminator) &&
+            Instance.Equals(x.AdditionalProperties, y.AdditionalProperties) &&
             x.AdditionalPropertiesAllowed == y.AdditionalPropertiesAllowed &&
             x.AllOf.SequenceEqual(y.AllOf, Instance) &&
             x.AnyOf.SequenceEqual(y.AnyOf, Instance) &&
             x.Deprecated == y.Deprecated &&
             OpenApiAnyComparer.Instance.Equals(x.Default, y.Default) &&
             x.Description == y.Description &&
-            OpenApiDiscriminatorComparer.Instance.Equals(x.Discriminator, y.Discriminator) &&
             OpenApiAnyComparer.Instance.Equals(x.Example, y.Example) &&
             x.ExclusiveMaximum == y.ExclusiveMaximum &&
             x.ExclusiveMinimum == y.ExclusiveMinimum &&
-            x.Extensions.Count == y.Extensions.Count
-            && x.Extensions.Keys.All(k => y.Extensions.ContainsKey(k) && x.Extensions[k] is IOpenApiAny anyX && y.Extensions[k] is IOpenApiAny anyY && OpenApiAnyComparer.Instance.Equals(anyX, anyY)) &&
+            x.Extensions.Count == y.Extensions.Count &&
+            x.Extensions.Keys.All(k => y.Extensions.TryGetValue(k, out var yValue) && x.Extensions[k] is IOpenApiAny anyX && yValue is IOpenApiAny anyY && OpenApiAnyComparer.Instance.Equals(anyX, anyY)) &&
             OpenApiExternalDocsComparer.Instance.Equals(x.ExternalDocs, y.ExternalDocs) &&
             x.Enum.SequenceEqual(y.Enum, OpenApiAnyComparer.Instance) &&
-            x.Format == y.Format &&
             Instance.Equals(x.Items, y.Items) &&
             x.Title == y.Title &&
-            x.Type == y.Type &&
             x.Maximum == y.Maximum &&
             x.MaxItems == y.MaxItems &&
             x.MaxLength == y.MaxLength &&
@@ -58,15 +62,13 @@ public bool Equals(OpenApiSchema? x, OpenApiSchema? y)
             Instance.Equals(x.Not, y.Not) &&
             x.Nullable == y.Nullable &&
             x.Pattern == y.Pattern &&
-            x.Properties.Keys.All(k => y.Properties.ContainsKey(k) && Instance.Equals(x.Properties[k], y.Properties[k])) &&
             x.ReadOnly == y.ReadOnly &&
             x.Required.Order().SequenceEqual(y.Required.Order()) &&
             OpenApiReferenceComparer.Instance.Equals(x.Reference, y.Reference) &&
             x.UniqueItems == y.UniqueItems &&
             x.UnresolvedReference == y.UnresolvedReference &&
             x.WriteOnly == y.WriteOnly &&
-            OpenApiXmlComparer.Instance.Equals(x.Xml, y.Xml) &&
-            SchemaIdEquals(x, y);
+            OpenApiXmlComparer.Instance.Equals(x.Xml, y.Xml);
     }
 
     private static bool SchemaIdEquals(OpenApiSchema x, OpenApiSchema y)

src/OpenApi/src/Comparers/OpenApiXmlComparer.cs

@@ -31,7 +31,7 @@ public bool Equals(OpenApiXml? x, OpenApiXml? y)
             x.Attribute == y.Attribute &&
             x.Wrapped == y.Wrapped &&
             x.Extensions.Count == y.Extensions.Count
-            && x.Extensions.Keys.All(k => y.Extensions.ContainsKey(k) && y.Extensions[k] == x.Extensions[k]);
+            && x.Extensions.Keys.All(k => y.Extensions.TryGetValue(k, out var yValue) && yValue == x.Extensions[k]);
     }
 
     public int GetHashCode(OpenApiXml obj)