public UnlaunchFeature Evaluate(FeatureFlag flag, UnlaunchUser user)
{
var evaluationReasonRef = new AtomicReference <string>(string.Empty);
var variation = EvaluateInternal(flag, user, evaluationReasonRef);
return(new UnlaunchFeature(flag.Key, variation.Key, variation.Properties, evaluationReasonRef.Get()));
}
private static Variation GetVariationIfUserInAllowList(FeatureFlag flag, UnlaunchUser user)
{
foreach (var variation in flag.Variations)
{
if (variation.AllowList != null)
{
var allowList = new HashSet <string>(variation.AllowList.Split(','));
if (allowList.Contains(user.GetId()))
{
return(variation);
}
}
}
return(null);
}
private bool CheckDependencies(FeatureFlag featureFlag, UnlaunchUser user)
{
var prerequisiteFlags = featureFlag.PrerequisiteFlags;
if (prerequisiteFlags == null || !prerequisiteFlags.Any())
{
return(true);
}
foreach (var flag in prerequisiteFlags.Keys)
{
var variation = EvaluateInternal(flag, user, null);
if (variation.Key != prerequisiteFlags[flag].Key)
{
Logger.Info($"PREREQUISITE_FAILED,{flag.Key},{user.GetId()}");
return(false);
}
}
return(true);
}
private Variation EvaluateInternal(FeatureFlag flag, UnlaunchUser user, AtomicReference <string> evaluationReasonRef)
{
if (flag == null)
{
throw new ArgumentException("unlaunchFlag must not be null");
}
if (user == null)
{
throw new ArgumentException("user must not be null");
}
Variation variationToServe;
var evaluationReason = string.Empty;
if (!flag.Enabled)
{
Logger.Debug($"FLAG_DISABLED, {flag.Key}, OFF_VARIATION is served to user {user.GetId()}");
variationToServe = flag.OffVariation;
evaluationReason = "Default Variation served. Because the flag is disabled.";
}
else if (!CheckDependencies(flag, user))
{
Logger.Info($"PREREQUISITE_FAILED for flag {flag.Key}, OFF_VARIATION is served to user {user.GetId()}");
variationToServe = flag.OffVariation;
evaluationReason = "Default Variation served. Because Pre-requisite failed.";
}
else if ((variationToServe = GetVariationIfUserInAllowList(flag, user)) != null)
{
Logger.Info($"USER_IN_TARGET_USER for flag {flag.Key}, VARIATION {variationToServe} is served to user {user.GetId()}");
evaluationReason = $"Target User rules matched for userId: {user.GetId()}";
}
else
{
var bucketNumber = GetBucket(user.GetId(), flag.Key);
foreach (var rule in flag.Rules)
{
if (!rule.IsDefault() && rule.Matches(user))
{
variationToServe = GetVariationToServeByRule(rule, bucketNumber);
Logger.Debug($"RULE_MATCHED for flag {flag.Key}, {variationToServe.Key} Target Rule is served to user {user.GetId()}");
evaluationReason = $"Targeting Rule (priority #{rule.GetPriority()}) matched.";
break;
}
}
// No variation matched by rule. Use the default rule.
if (variationToServe == null)
{
var defaultRule = flag.DefaultRule;
variationToServe = GetVariationToServeByRule(defaultRule, bucketNumber);
Logger.Debug($"RULE_NOT_MATCHED for flag {flag.Key}, {variationToServe.Key} Default Rule is served to user {user.GetId()}");
evaluationReason = "Default Rule served. This is because the flag is Enabled and Target User and Targeting Rules didn't match.";
}
}
evaluationReasonRef?.Set(evaluationReason);
return(variationToServe);
}
public bool Matches(UnlaunchUser user)
{
return(_conditions.All(condition => condition.Match(user)));
}
public bool Match(UnlaunchUser user)
{
return(user.GetAttributes().ContainsKey(_attribute) && _operator.Apply(_value, user.GetAttributes()[_attribute], _type));
}
