Add the high-contention warning

If the number of serialization-related retry is greater than predefined
value (currently 8) a warning is issued instead of the usual debug
message. This is to tell administrator that something wrong - i.e. high
contention - is occurring.

(backported from commit cf323c7)

repo/repo-sql-impl/src/main/java/com/evolveum/midpoint/repo/sql/SqlRepositoryServiceImpl.java

@@ -99,6 +99,7 @@
 public class SqlRepositoryServiceImpl extends SqlBaseService implements RepositoryService {
 
     public static final String PERFORMANCE_LOG_NAME = SqlRepositoryServiceImpl.class.getName() + ".performance";
+    public static final int MAIN_LOG_WARN_THRESHOLD = 8;
 
     private static final Trace LOGGER = TraceManager.getTrace(SqlRepositoryServiceImpl.class);
     private static final Trace LOGGER_PERFORMANCE = TraceManager.getTrace(PERFORMANCE_LOG_NAME);

repo/repo-sql-impl/src/main/java/com/evolveum/midpoint/repo/sql/helpers/BaseHelper.java

@@ -209,9 +209,13 @@ public int logOperationAttempt(String oid, String operation, int attempt, Runtim
 			LOGGER.trace("Waiting: attempt = " + attempt + ", waitTimeInterval = 0.." + waitTimeInterval + ", waitTime = " + waitTime);
 		}
 
-		if (LOGGER.isDebugEnabled()) {
+		if (attempt >= SqlRepositoryServiceImpl.MAIN_LOG_WARN_THRESHOLD) {
+			LOGGER.warn("A serialization-related problem occurred when {} object with oid '{}', retrying after "
+							+ "{} ms (this was attempt {} of {})\n{}: {}", operation, oid, waitTime,
+					attempt, LOCKING_MAX_ATTEMPTS, ex.getClass().getSimpleName(), ex.getMessage());
+		} else {
 			LOGGER.debug("A serialization-related problem occurred when {} object with oid '{}', retrying after "
-					+ "{} ms (this was attempt {} of {})\n{}: {}", operation, oid, waitTime,
+							+ "{} ms (this was attempt {} of {})\n{}: {}", operation, oid, waitTime,
 					attempt, LOCKING_MAX_ATTEMPTS, ex.getClass().getSimpleName(), ex.getMessage());
 		}