Simplify EvaluateContext + improve perf. of user attribute retrieval …

…during evaluation + reduce allocations

src/ConfigCatClient/Evaluation/EvaluateContext.cs

@@ -1,5 +1,4 @@
 using System.Collections.Generic;
-using System.Diagnostics.CodeAnalysis;
 using ConfigCat.Client.Utils;
 
 namespace ConfigCat.Client.Evaluation;
@@ -8,16 +7,9 @@ internal struct EvaluateContext
 {
     public readonly string Key;
     public readonly Setting Setting;
+    public readonly User? User;
     public readonly IReadOnlyDictionary<string, Setting> Settings;
 
-    private readonly User? user;
-
-    [MemberNotNullWhen(true, nameof(UserAttributes))]
-    public readonly bool IsUserAvailable => this.user is not null;
-
-    private IReadOnlyDictionary<string, object>? userAttributes;
-    public IReadOnlyDictionary<string, object>? UserAttributes => this.userAttributes ??= this.user?.GetAllAttributes();
-
     private List<string>? visitedFlags;
     public List<string> VisitedFlags => this.visitedFlags ??= new List<string>();
 
@@ -30,19 +22,17 @@ public EvaluateContext(string key, Setting setting, User? user, IReadOnlyDiction
     {
         this.Key = key;
         this.Setting = setting;
-        this.user = user;
+        this.User = user;
         this.Settings = settings;
 
-        this.userAttributes = null;
         this.visitedFlags = null;
         this.IsMissingUserObjectLogged = this.IsMissingUserObjectAttributeLogged = false;
         this.LogBuilder = null; // initialized by RolloutEvaluator.Evaluate
     }
 
-    public EvaluateContext(string key, Setting setting, ref EvaluateContext dependentFlagContext)
-        : this(key, setting, dependentFlagContext.user, dependentFlagContext.Settings)
+    public EvaluateContext(string key, Setting setting, in EvaluateContext dependentFlagContext)
+        : this(key, setting, dependentFlagContext.User, dependentFlagContext.Settings)
     {
-        this.userAttributes = dependentFlagContext.UserAttributes;
         this.visitedFlags = dependentFlagContext.VisitedFlags; // crucial to use the property here to make sure the list is created!
         this.LogBuilder = dependentFlagContext.LogBuilder;
     }

src/ConfigCatClient/Evaluation/RolloutEvaluator.cs

@@ -2,7 +2,6 @@
 using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
 using System.Globalization;
-using System.Linq;
 using System.Text;
 using ConfigCat.Client.Utils;
 using ConfigCat.Client.Versioning;
@@ -35,9 +34,9 @@ public EvaluateResult Evaluate<T>(T defaultValue, ref EvaluateContext context, [
 
             logBuilder.Append($"Evaluating '{context.Key}'");
 
-            if (context.IsUserAvailable)
+            if (context.User is not null)
             {
-                logBuilder.Append($" for User '{context.UserAttributes.Serialize()}'");
+                logBuilder.Append($" for User '{context.User.GetAllAttributes().Serialize()}'");
             }
 
             logBuilder.IncreaseIndent();
@@ -178,7 +177,7 @@ private bool TryEvaluatePercentageOptions(PercentageOption[] percentageOptions,
     {
         var logBuilder = context.LogBuilder;
 
-        if (!context.IsUserAvailable)
+        if (context.User is null)
         {
             logBuilder?.NewLine("Skipping % options because the User Object is missing.");
 
@@ -192,9 +191,21 @@ private bool TryEvaluatePercentageOptions(PercentageOption[] percentageOptions,
             return false;
         }
 
-        var percentageOptionsAttributeName = context.Setting.PercentageOptionsAttribute ?? nameof(User.Identifier);
+        string percentageOptionsAttributeName;
+        object? percentageOptionsAttributeValue;
 
-        if (!context.UserAttributes.TryGetValue(percentageOptionsAttributeName, out var percentageOptionsAttributeValue))
+        if (context.Setting.PercentageOptionsAttribute is null)
+        {
+            percentageOptionsAttributeName = nameof(User.Identifier);
+            percentageOptionsAttributeValue = context.User.Identifier;
+        }
+        else
+        {
+            percentageOptionsAttributeName = context.Setting.PercentageOptionsAttribute;
+            percentageOptionsAttributeValue = context.User.GetAttribute(percentageOptionsAttributeName);
+        }
+
+        if (percentageOptionsAttributeValue is null)
         {
             logBuilder?.NewLine().Append($"Skipping % options because the User.{percentageOptionsAttributeName} attribute is missing.");
 
@@ -334,7 +345,7 @@ private bool EvaluateUserCondition(UserCondition condition, string contextSalt,
         var logBuilder = context.LogBuilder;
         logBuilder?.AppendUserCondition(condition);
 
-        if (!context.IsUserAvailable)
+        if (context.User is null)
         {
             if (!context.IsMissingUserObjectLogged)
             {
@@ -347,8 +358,9 @@ private bool EvaluateUserCondition(UserCondition condition, string contextSalt,
         }
 
         var userAttributeName = condition.ComparisonAttribute ?? throw new InvalidOperationException("Comparison attribute name is missing.");
+        var userAttributeValue = context.User.GetAttribute(userAttributeName);
 
-        if (!context.UserAttributes.TryGetValue(userAttributeName, out var userAttributeValue) || userAttributeValue is string { Length: 0 })
+        if (userAttributeValue is null || userAttributeValue is string { Length: 0 })
         {
             this.logger.UserObjectAttributeIsMissing(condition.ToString(), context.Key, userAttributeName);
             error = string.Format(CultureInfo.InvariantCulture, MissingUserAttributeError, userAttributeName);
@@ -723,7 +735,7 @@ private bool EvaluatePrerequisiteFlagCondition(PrerequisiteFlagCondition conditi
             throw new InvalidOperationException($"Circular dependency detected between the following depending flags: {dependencyCycle}.");
         }
 
-        var prerequisiteFlagContext = new EvaluateContext(prerequisiteFlagKey!, prerequisiteFlag!, ref context);
+        var prerequisiteFlagContext = new EvaluateContext(prerequisiteFlagKey!, prerequisiteFlag!, context);
 
         logBuilder?
             .NewLine("(")
@@ -762,7 +774,7 @@ private bool EvaluateSegmentCondition(SegmentCondition condition, ref EvaluateCo
         var logBuilder = context.LogBuilder;
         logBuilder?.AppendSegmentCondition(condition);
 
-        if (!context.IsUserAvailable)
+        if (context.User is null)
         {
             if (!context.IsMissingUserObjectLogged)
             {

src/ConfigCatClient/User.cs

@@ -78,6 +78,18 @@ public IDictionary<string, object> Custom
         get => this.custom ??= new Dictionary<string, object>();
         set => this.custom = value;
     }
+
+    internal object? GetAttribute(string name)
+    {
+        return name switch
+        {
+            nameof(Identifier) => Identifier,
+            nameof(Email) => Email,
+            nameof(Country) => Country,
+            _ => this.custom is not null && this.custom.TryGetValue(name, out var value) ? value : null
+        };
+    }
+
     /// <summary>
     /// Returns all attributes of the user.
     /// </summary>