update: enhance DecisionService, FeatureDecision, and DecisionResponse to support CMAB UUID handling

Author: FarhanAnjum-opti

core-api/src/main/java/com/optimizely/ab/bucketing/DecisionService.java

@@ -60,6 +60,7 @@
  *   3. Checking sticky bucketing
  *   4. Checking audience targeting
  *   5. Using Murmurhash3 to bucket the user.
+ *   6. Handling CMAB (Contextual Multi-Armed Bandit) experiments for dynamic variation selection
  */
 public class DecisionService {
 
@@ -153,18 +154,19 @@ public DecisionResponse<Variation> getVariation(@Nonnull Experiment experiment,
         reasons.merge(decisionMeetAudience.getReasons());
         if (decisionMeetAudience.getResult()) {
             String bucketingId = getBucketingId(user.getUserId(), user.getAttributes());
-
+            String cmabUUID = null;
             if (isCmabExperiment(experiment)) {
                 DecisionResponse<CmabDecision> cmabDecision = getDecisionForCmabExperiment(projectConfig, experiment, user, bucketingId, options);
                 reasons.merge(cmabDecision.getReasons());
 
                 if (cmabDecision.isError()) {
-                    return new DecisionResponse<>(null, reasons, true);
+                    return new DecisionResponse<>(null, reasons, true, null);
                 }
 
                 CmabDecision cmabResult = cmabDecision.getResult();
                 if (cmabResult != null) {
                     String variationId = cmabResult.getVariationId();
+                    cmabUUID = cmabResult.getCmabUUID();
                     variation = experiment.getVariationIdToVariationMap().get(variationId);
                 }
             } else {
@@ -182,7 +184,7 @@ public DecisionResponse<Variation> getVariation(@Nonnull Experiment experiment,
                 }
             }
 
-            return new DecisionResponse(variation, reasons);
+            return new DecisionResponse<>(variation, reasons, false, cmabUUID);
         }
 
         String message = reasons.addInfo("User \"%s\" does not meet conditions to be in experiment \"%s\".", user.getUserId(), experiment.getKey());

core-api/src/main/java/com/optimizely/ab/bucketing/FeatureDecision.java

@@ -39,6 +39,12 @@ public class FeatureDecision {
     @Nullable
     public DecisionSource decisionSource;
 
+    /**
+     * The CMAB UUID for Contextual Multi-Armed Bandit experiments.
+     */
+    @Nullable
+    public String cmabUUID;
+
     public enum DecisionSource {
         FEATURE_TEST("feature-test"),
         ROLLOUT("rollout"),
@@ -68,6 +74,23 @@ public FeatureDecision(@Nullable ExperimentCore experiment, @Nullable Variation
         this.experiment = experiment;
         this.variation = variation;
         this.decisionSource = decisionSource;
+        this.cmabUUID = null;
+    }
+
+    /**
+     * Initialize a FeatureDecision object with CMAB UUID.
+     *
+     * @param experiment     The {@link ExperimentCore} the Feature is associated with.
+     * @param variation      The {@link Variation} the user was bucketed into.
+     * @param decisionSource The source of the variation.
+     * @param cmabUUID       The CMAB UUID for Contextual Multi-Armed Bandit experiments.
+     */
+    public FeatureDecision(@Nullable ExperimentCore experiment, @Nullable Variation variation,
+                           @Nullable DecisionSource decisionSource, @Nullable String cmabUUID) {
+        this.experiment = experiment;
+        this.variation = variation;
+        this.decisionSource = decisionSource;
+        this.cmabUUID = cmabUUID;
     }
 
     @Override
@@ -79,13 +102,15 @@ public boolean equals(Object o) {
 
         if (variation != null ? !variation.equals(that.variation) : that.variation != null)
             return false;
-        return decisionSource == that.decisionSource;
+        if (decisionSource != that.decisionSource) return false;
+        return cmabUUID != null ? cmabUUID.equals(that.cmabUUID) : that.cmabUUID == null;
     }
 
     @Override
     public int hashCode() {
         int result = variation != null ? variation.hashCode() : 0;
         result = 31 * result + (decisionSource != null ? decisionSource.hashCode() : 0);
+        result = 31 * result + (cmabUUID != null ? cmabUUID.hashCode() : 0);
         return result;
     }
 }

core-api/src/main/java/com/optimizely/ab/optimizelydecision/DecisionResponse.java

@@ -23,23 +23,25 @@ public class DecisionResponse<T> {
     private T result;
     private DecisionReasons reasons;
     private boolean error;
+    private String cmabUUID;
 
-    public DecisionResponse(@Nullable T result, @Nonnull DecisionReasons reasons, @Nonnull boolean error) {
+    public DecisionResponse(@Nullable T result, @Nonnull DecisionReasons reasons, @Nonnull boolean error, @Nullable String cmabUUID) {
         this.result = result;
         this.reasons = reasons;
         this.error = error;
+        this.cmabUUID = cmabUUID;
     }
 
     public DecisionResponse(@Nullable T result, @Nonnull DecisionReasons reasons) {
-        this(result, reasons, false);
+        this(result, reasons, false, null);
     }
 
     public static <E> DecisionResponse<E> responseNoReasons(@Nullable E result) {
-        return new DecisionResponse<>(result, DefaultDecisionReasons.newInstance(), false);
+        return new DecisionResponse<>(result, DefaultDecisionReasons.newInstance(), false, null);
     }
 
     public static <E> DecisionResponse<E> nullNoReasons() {
-        return new DecisionResponse<>(null, DefaultDecisionReasons.newInstance(), false);
+        return new DecisionResponse<>(null, DefaultDecisionReasons.newInstance(), false, null);
     }
 
     @Nullable
@@ -56,4 +58,9 @@ public DecisionReasons getReasons() {
     public boolean isError(){
         return error;
     }
+
+    @Nullable
+    public String getCmabUUID() {
+        return cmabUUID;
+    }
 }