Feature/force bucketing (#136)

* added force bucketing
* get test working
* unit test forced variations
* fix EventBuilderV2Test using AssertNotEqual
* methods and map in project config. decision logic in decision service
* use variation and experiment ids instead of key for storage.  use putIfAbsent
* added logging for projectConfig

Author: thomaszurkan-optimizely

core-api/src/main/java/com/optimizely/ab/Optimizely.java

@@ -53,6 +53,7 @@
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
 
 /**
  * Top-level container class for Optimizely functionality.
@@ -615,6 +616,42 @@ Variation getVariation(@Nonnull String experimentKey,
         return decisionService.getVariation(experiment,userId,filteredAttributes);
     }
 
+    /**
+     * Force a user into a variation for a given experiment.
+     * The forced variation value does not persist across application launches.
+     * If the experiment key is not in the project file, this call fails and returns false.
+     * If the variationKey is not in the experiment, this call fails.
+     * @param experimentKey The key for the experiment.
+     * @param userId The user ID to be used for bucketing.
+     * @param variationKey The variation key to force the user into.  If the variation key is null
+     *                     then the forcedVariation for that experiment is removed.
+     *
+     * @return boolean A boolean value that indicates if the set completed successfully.
+     */
+    public boolean setForcedVariation(@Nonnull String experimentKey,
+                                      @Nonnull String userId,
+                                      @Nullable String variationKey) {
+
+
+        return projectConfig.setForcedVariation(experimentKey, userId, variationKey);
+    }
+
+    /**
+     * Gets the forced variation for a given user and experiment.
+     * This method just calls into the {@link com.optimizely.ab.config.ProjectConfig#getForcedVariation(String, String)}
+     * method of the same signature.
+     *
+     * @param experimentKey The key for the experiment.
+     * @param userId The user ID to be used for bucketing.
+     *
+     * @return The variation the user was bucketed into. This value can be null if the
+     * forced variation fails.
+     */
+    public @Nullable Variation getForcedVariation(@Nonnull String experimentKey,
+                                        @Nonnull String userId) {
+        return projectConfig.getForcedVariation(experimentKey, userId);
+    }
+
     /**
      * @return the current {@link ProjectConfig} instance.
      */

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

@@ -82,8 +82,14 @@ public DecisionService(@Nonnull Bucketer bucketer,
             return null;
         }
 
+        // look for forced bucketing first.
+        Variation variation = projectConfig.getForcedVariation(experiment.getKey(), userId);
+
         // check for whitelisting
-        Variation variation = getWhitelistedVariation(experiment, userId);
+        if (variation == null) {
+            variation = getWhitelistedVariation(experiment, userId);
+        }
+
         if (variation != null) {
             return variation;
         }

core-api/src/main/java/com/optimizely/ab/config/ProjectConfig.java

@@ -19,14 +19,18 @@
 import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
 import com.optimizely.ab.config.audience.Audience;
 import com.optimizely.ab.config.audience.Condition;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
+import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 import javax.annotation.concurrent.Immutable;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
 
 /**
  * Represents the Optimizely Project configuration.
@@ -54,6 +58,10 @@ public String toString() {
         }
     }
 
+    // logger
+    private static final Logger logger = LoggerFactory.getLogger(ProjectConfig.class);
+
+    // ProjectConfig properties
     private final String accountId;
     private final String projectId;
     private final String revision;
@@ -85,6 +93,14 @@ public String toString() {
     private final Map<String, Map<String, LiveVariableUsageInstance>> variationToLiveVariableUsageInstanceMapping;
     private final Map<String, Experiment> variationIdToExperimentMapping;
 
+    /**
+     *  Forced variations supersede any other mappings.  They are transient and are not persistent or part of
+     * the actual datafile. This contains all the forced variations
+     * set by the user by calling {@link ProjectConfig#setForcedVariation(String, String, String)} (it is not the same as the
+     * whitelisting forcedVariations data structure in the Experiments class).
+     */
+    private transient ConcurrentHashMap<String, ConcurrentHashMap<String, String>> forcedVariationMapping = new ConcurrentHashMap<String, ConcurrentHashMap<String, String>>();
+
     // v2 constructor
     public ProjectConfig(String accountId, String projectId, String version, String revision, List<Group> groups,
                          List<Experiment> experiments, List<Attribute> attributes, List<EventType> eventType,
@@ -318,6 +334,136 @@ public Map<String, FeatureFlag> getFeatureKeyMapping() {
         return featureKeyMapping;
     }
 
+    public ConcurrentHashMap<String, ConcurrentHashMap<String, String>> getForcedVariationMapping() { return forcedVariationMapping; }
+
+    /**
+     * Force a user into a variation for a given experiment.
+     * The forced variation value does not persist across application launches.
+     * If the experiment key is not in the project file, this call fails and returns false.
+     *
+     * @param experimentKey The key for the experiment.
+     * @param userId The user ID to be used for bucketing.
+     * @param variationKey The variation key to force the user into.  If the variation key is null
+     *                     then the forcedVariation for that experiment is removed.
+     *
+     * @return boolean A boolean value that indicates if the set completed successfully.
+     */
+    public boolean setForcedVariation(@Nonnull String experimentKey,
+                                      @Nonnull String userId,
+                                      @Nullable String variationKey) {
+
+        // if the experiment is not a valid experiment key, don't set it.
+        Experiment experiment = getExperimentKeyMapping().get(experimentKey);
+        if (experiment == null){
+            logger.error("Experiment {} does not exist in ProjectConfig for project {}", experimentKey, projectId);
+            return false;
+        }
+
+        Variation variation = null;
+
+        // keep in mind that you can pass in a variationKey that is null if you want to
+        // remove the variation.
+        if (variationKey != null) {
+            variation = experiment.getVariationKeyToVariationMap().get(variationKey);
+            // if the variation is not part of the experiment, return false.
+            if (variation == null) {
+                logger.error("Variation {} does not exist for experiment {}", variationKey, experimentKey);
+                return false;
+            }
+        }
+
+        // if the user id is invalid, return false.
+        if (userId == null || userId.trim().isEmpty()) {
+            logger.error("User ID is invalid");
+            return false;
+        }
+
+        ConcurrentHashMap<String, String> experimentToVariation;
+        if (!forcedVariationMapping.containsKey(userId)) {
+            forcedVariationMapping.putIfAbsent(userId, new ConcurrentHashMap<String, String>());
+        }
+        experimentToVariation = forcedVariationMapping.get(userId);
+
+        boolean retVal = true;
+        // if it is null remove the variation if it exists.
+        if (variationKey == null) {
+            String removedVariationId = experimentToVariation.remove(experiment.getId());
+            if (removedVariationId != null) {
+                Variation removedVariation = experiment.getVariationIdToVariationMap().get(removedVariationId);
+                if (removedVariation != null) {
+                    logger.debug("Variation mapped to experiment \"%s\" has been removed for user \"%s\"", experiment.getKey(), userId);
+                }
+                else {
+                    logger.debug("Removed forced variation that did not exist in experiment");
+                }
+            }
+            else {
+                logger.debug("No variation for experiment {}", experimentKey);
+                retVal = false;
+            }
+        }
+        else {
+            String previous = experimentToVariation.put(experiment.getId(), variation.getId());
+            logger.debug("Set variation \"%s\" for experiment \"%s\" and user \"%s\" in the forced variation map.",
+                    variation.getKey(), experiment.getKey(), userId);
+            if (previous != null) {
+                Variation previousVariation = experiment.getVariationIdToVariationMap().get(previous);
+                if (previousVariation != null) {
+                    logger.debug("forced variation {} replaced forced variation {} in forced variation map.",
+                            variation.getKey(), previousVariation.getKey());
+                }
+            }
+        }
+
+        return retVal;
+    }
+
+    /**
+     * Gets the forced variation for a given user and experiment.
+     *
+     * @param experimentKey The key for the experiment.
+     * @param userId The user ID to be used for bucketing.
+     *
+     * @return The variation the user was bucketed into. This value can be null if the
+     * forced variation fails.
+     */
+    public @Nullable Variation getForcedVariation(@Nonnull String experimentKey,
+                                                  @Nonnull String userId) {
+
+        // if the user id is invalid, return false.
+        if (userId == null || userId.trim().isEmpty()) {
+            logger.error("User ID is invalid");
+            return null;
+        }
+
+        if (experimentKey == null || experimentKey.isEmpty()) {
+            logger.error("experiment key is invalid");
+            return null;
+        }
+
+        Map<String, String> experimentToVariation = getForcedVariationMapping().get(userId);
+        if (experimentToVariation != null) {
+            Experiment experiment = getExperimentKeyMapping().get(experimentKey);
+            if (experiment == null)  {
+                logger.debug("No experiment \"%s\" mapped to user \"%s\" in the forced variation map ", experimentKey, userId);
+                return null;
+            }
+            String variationId = experimentToVariation.get(experiment.getId());
+            if (variationId != null) {
+                Variation variation =  experiment.getVariationIdToVariationMap().get(variationId);
+                if (variation != null) {
+                    logger.debug("Variation \"%s\" is mapped to experiment \"%s\" and user \"%s\" in the forced variation map",
+                            variation.getKey(), experimentKey, userId);
+                    return variation;
+                }
+            }
+            else {
+                logger.debug("No variation for experiment \"%s\" mapped to user \"%s\" in the forced variation map ", experimentKey, userId);
+            }
+        }
+        return null;
+    }
+
     @Override
     public String toString() {
         return "ProjectConfig{" +
@@ -344,6 +490,7 @@ public String toString() {
                 ", groupIdMapping=" + groupIdMapping +
                 ", liveVariableIdToExperimentsMapping=" + liveVariableIdToExperimentsMapping +
                 ", variationToLiveVariableUsageInstanceMapping=" + variationToLiveVariableUsageInstanceMapping +
+                ", forcedVariationMapping=" + forcedVariationMapping +
                 ", variationIdToExperimentMapping=" + variationIdToExperimentMapping +
                 '}';
     }