Merge "Return a message to the user if request fails due to LOCK_FAILURE"

java/com/google/gerrit/server/ExceptionHookImpl.java

@@ -25,6 +25,11 @@ import org.eclipse.jgit.lib.RefUpdate;
  * a retry of the failed operation.
  */
 public class ExceptionHookImpl implements ExceptionHook {
+  private static final String LOCK_FAILURE_USER_MESSAGE =
+      "Updating a ref failed with LOCK_FAILURE.\n"
+          + "This may be a temporary issue due to concurrent updates.\n"
+          + "Please retry later.";
+
   @Override
   public boolean shouldRetry(Throwable throwable) {
     return isLockFailure(throwable);
@@ -38,6 +43,14 @@ public class ExceptionHookImpl implements ExceptionHook {
     return Optional.empty();
   }
 
+  @Override
+  public Optional<String> getUserMessage(Throwable throwable) {
+    if (isLockFailure(throwable)) {
+      return Optional.of(LOCK_FAILURE_USER_MESSAGE);
+    }
+    return Optional.empty();
+  }
+
   private static boolean isLockFailure(Throwable throwable) {
     return isMatching(throwable, t -> t instanceof LockFailureException);
   }