Merge changes I383a3c20,I25631902

* changes:
  Add debug logs for reviewer suggestion
  CurrentUser: Add method for getting a loggable name

java/com/google/gerrit/server/CurrentUser.java

@@ -95,6 +95,11 @@ public abstract class CurrentUser {
     return Optional.empty();
   }
 
+  /** @return unique name of the user for logging, never {@code null} */
+  public String getLoggableName() {
+    return getUserName().orElseGet(() -> getClass().getSimpleName());
+  }
+
   /** Check if user is the IdentifiedUser */
   public boolean isIdentifiedUser() {
     return false;

java/com/google/gerrit/server/IdentifiedUser.java

@@ -323,6 +323,7 @@ public class IdentifiedUser extends CurrentUser {
   }
 
   /** @return unique name of the user for logging, never {@code null} */
+  @Override
   public String getLoggableName() {
     return getUserName()
         .orElseGet(

java/com/google/gerrit/server/restapi/change/ReviewersUtil.java

@@ -65,6 +65,8 @@ import java.util.List;
 import java.util.Objects;
 import java.util.Set;
 import org.eclipse.jgit.errors.ConfigInvalidException;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 public class ReviewersUtil {
   @Singleton
@@ -110,6 +112,8 @@ public class ReviewersUtil {
     }
   }
 
+  private static final Logger log = LoggerFactory.getLogger(ReviewersUtil.class);
+
   // Generate a candidate list at 2x the size of what the user wants to see to
   // give the ranking algorithm a good set of candidates it can work with
   private static final int CANDIDATE_LIST_MULTIPLIER = 2;
@@ -163,20 +167,29 @@ public class ReviewersUtil {
       VisibilityControl visibilityControl,
       boolean excludeGroups)
       throws IOException, OrmException, ConfigInvalidException, PermissionBackendException {
+    CurrentUser currentUser = self.get();
+    log.debug(
+        "Suggesting reviewers for change {} to user {}.",
+        changeNotes.getChangeId().get(),
+        currentUser.getLoggableName());
     String query = suggestReviewers.getQuery();
+    log.debug("Query: {}", query);
     int limit = suggestReviewers.getLimit();
 
     if (!suggestReviewers.getSuggestAccounts()) {
+      log.debug("Reviewer suggestion is disabled.");
       return Collections.emptyList();
     }
 
     List<Account.Id> candidateList = new ArrayList<>();
     if (!Strings.isNullOrEmpty(query)) {
       candidateList = suggestAccounts(suggestReviewers);
+      log.debug("Candidate list: {}", candidateList);
     }
 
     List<Account.Id> sortedRecommendations =
         recommendAccounts(changeNotes, suggestReviewers, projectState, candidateList);
+    log.debug("Sorted recommendations: {}", sortedRecommendations);
 
     // Filter accounts by visibility and enforce limit
     List<Account.Id> filteredRecommendations = new ArrayList<>();
@@ -192,20 +205,40 @@ public class ReviewersUtil {
         }
       }
     }
+    log.debug("Filtered recommendations: {}", filteredRecommendations);
 
-    List<SuggestedReviewerInfo> suggestedReviewer = loadAccounts(filteredRecommendations);
-    if (!excludeGroups && suggestedReviewer.size() < limit && !Strings.isNullOrEmpty(query)) {
+    List<SuggestedReviewerInfo> suggestedReviewers = loadAccounts(filteredRecommendations);
+    if (!excludeGroups && suggestedReviewers.size() < limit && !Strings.isNullOrEmpty(query)) {
       // Add groups at the end as individual accounts are usually more
       // important.
-      suggestedReviewer.addAll(
+      suggestedReviewers.addAll(
           suggestAccountGroups(
-              suggestReviewers, projectState, visibilityControl, limit - suggestedReviewer.size()));
+              suggestReviewers,
+              projectState,
+              visibilityControl,
+              limit - suggestedReviewers.size()));
     }
 
-    if (suggestedReviewer.size() <= limit) {
-      return suggestedReviewer;
+    if (suggestedReviewers.size() > limit) {
+      suggestedReviewers = suggestedReviewers.subList(0, limit);
+      log.debug("Limited suggested reviewers to {} accounts.", limit);
     }
-    return suggestedReviewer.subList(0, limit);
+    log.debug(
+        "Suggested reviewers: {}",
+        suggestedReviewers
+            .stream()
+            .map(
+                r -> {
+                  if (r.account != null) {
+                    return "a/" + r.account._accountId;
+                  } else if (r.group != null) {
+                    return "g/" + r.group.id;
+                  } else {
+                    return "";
+                  }
+                })
+            .collect(toList()));
+    return suggestedReviewers;
   }
 
   private List<Account.Id> suggestAccounts(SuggestReviewers suggestReviewers) throws OrmException {