add log entry and throw exception when message limit is exceeded (#3126)

Author: Vladimir Kotal

opengrok-indexer/src/main/java/org/opengrok/indexer/web/messages/MessagesContainer.java

@@ -28,6 +28,8 @@
 import com.fasterxml.jackson.databind.SerializerProvider;
 import com.fasterxml.jackson.databind.annotation.JsonSerialize;
 import com.fasterxml.jackson.databind.ser.std.StdSerializer;
+import org.opengrok.indexer.logger.LoggerFactory;
+
 import javax.validation.constraints.NotBlank;
 
 import java.io.IOException;
@@ -45,10 +47,14 @@
 import java.util.TimerTask;
 import java.util.TreeSet;
 import java.util.function.Predicate;
+import java.util.logging.Level;
+import java.util.logging.Logger;
 import java.util.stream.Collectors;
 
 public class MessagesContainer {
 
+    private static final Logger LOGGER = LoggerFactory.getLogger(MessagesContainer.class);
+
     public static final String MESSAGES_MAIN_PAGE_TAG = "main";
 
     private static final int DEFAULT_MESSAGE_LIMIT = 100;
@@ -121,7 +127,9 @@ public void addMessage(final Message m) {
             }
 
             if (isMessageLimitExceeded()) {
-                return;
+                LOGGER.log(Level.WARNING, "cannot add message to the system, " +
+                                "exceeded Configuration messageLimit of {0}", messageLimit);
+                throw new IllegalStateException("Cannot add message - message limit exceeded");
             }
 
             if (expirationTimer == null) {