User friendly map toString in StatisticsUtils (#2203)

Signed-off-by: Avgustin Marinov <Avgustin.Marinov@bosch.com>

hawkbit-repository/hawkbit-repository-jpa-eclipselink/src/main/java/org/eclipse/hawkbit/repository/jpa/Statistics.java

@@ -40,7 +40,7 @@ import org.springframework.scheduling.annotation.Scheduled;
  * <ol>
  *     <li>The Spring property spring.jpa.properties.eclipselink.profiler=PerformanceMonitor shall be set - enables Eclipselink statistics
  *         collecting</li>
- *     <li>By default the stdout log is disabled by setting hawkbit.jpa.statistics.dumpPeriodMS=9223372036854775807 (Long.MAX_VALUE) -
+ *     <li>By default the periodic stdout log is disabled by setting hawkbit.jpa.statistics.dumpPeriodMS=9223372036854775807 (Long.MAX_VALUE) -
  *         i.e. effectively <b>never</b>. If log is required it should be set to the required period</li>
  *     <li>The MeterRegistry shall be registered available - e.g. include org.springframework.boot:spring-boot-actuator-autoconfigure</li>
  *     <li>(?) When using in test the metrics MAYBE shall be enabled with @AutoConfigureObservability(tracing = false)</li>

hawkbit-repository/hawkbit-repository-jpa-hibernate/src/main/java/org/eclipse/hawkbit/repository/jpa/Statistics.java

@@ -25,7 +25,7 @@ import org.springframework.context.annotation.Configuration;
  * <ol>
  *     <li>The Spring property spring.jpa.properties.hibernate.generate_statistics=true shall be set - enables Hibernate statistics
  *         collecting</li>
- *     <li>If don't need log in the stdout set logging.level.org.hibernate.engine.internal.StatisticalLoggingSessionEventListener=WARN</li>
+ *     <li>If don't need periodic log (Slf4J) set logging.level.org.hibernate.engine.internal.StatisticalLoggingSessionEventListener=WARN</li>
  *     <li>The MeterRegistry shall be registered available - e.g. include org.springframework.boot:spring-boot-actuator-autoconfigure</li>
  *     <li>Hibernate reporting to micrometer shall be enabled - include org.hibernate.orm:hibernate-micrometer</li>
  *     <li>(?) When using in test the metrics MAYBE shall be enabled with @AutoConfigureObservability(tracing = false)</li>

hawkbit-repository/hawkbit-repository-jpa/src/main/java/org/eclipse/hawkbit/repository/jpa/utils/StatisticsUtils.java

@@ -26,11 +26,12 @@ import org.springframework.util.ObjectUtils;
 
 /**
  * (Experimental) Utility class to get some statistics.
+ * It's main purpose is to be used for debugging / testing (performance) purposes.
  */
 @NoArgsConstructor(access = AccessLevel.PRIVATE)
 public class StatisticsUtils {
 
-    private static final ThreadLocal<Map<String, Double>> LAST_COUNTERS = ThreadLocal.withInitial(HashMap::new);
+    private static final ThreadLocal<Map<String, Double>> LAST_COUNTERS = ThreadLocal.withInitial(MapUFToString::new);
 
     // for test purposes we may want to flush the statistics and to get diff from the last get int THIS thread
     public static Map<String, Double> diff() {
@@ -60,7 +61,7 @@ public class StatisticsUtils {
 
         Statistics.flush();
 
-        final Map<String, Double> counters = new HashMap<>();
+        final Map<String, Double> counters = new MapUFToString();
         meterRegistry.forEachMeter(m -> {
             final Meter.Id id = m.getId();
             if (id.getName().startsWith(Statistics.METER_PREFIX)) {
@@ -78,7 +79,7 @@ public class StatisticsUtils {
                 if (!ObjectUtils.isEmpty(tags)) {
                     key.append(" [");
                     tags.forEach(tag -> key.append(tag.getKey()).append('=').append(tag.getValue()).append(", "));
-                    key.setLength(key.length() - 2);
+                    key.setLength(key.length() - 2); // remove the last ", "
                     key.append(']');
                 }
                 counters.put(key.toString(), value);
@@ -88,4 +89,24 @@ public class StatisticsUtils {
         LAST_COUNTERS.set(counters);
         return counters;
     }
+
+    // Map with user-friendly toString, sorted and without the last ", "
+    private static class MapUFToString extends HashMap<String, Double> {
+
+        @Override
+        public String toString() {
+            if (isEmpty()) {
+                return "{}";
+            }
+
+            final StringBuilder sb = new StringBuilder("{");
+            entrySet().stream()
+                    .sorted()
+                    .forEach(e -> sb.append(e.getKey()).append(": ").append(e.getValue()).append(", "));
+            sb.setLength(sb.length() - 2); // remove the last ", "
+            sb.append("}");
+
+            return sb.toString();
+        }
+    }
 }

hawkbit-repository/hawkbit-repository-jpa/src/test/resources/jpa-test.properties

@@ -31,7 +31,7 @@ logging.level.org.eclipse.persistence=ERROR
 ## Enable Hibernate statistics
 #spring.jpa.properties.hibernate.generate_statistics=true
 ## Disables info log messages from Hibernate statistics
-logging.level.org.hibernate.engine.internal.StatisticalLoggingSessionEventListener=WARN
+#logging.level.org.hibernate.engine.internal.StatisticalLoggingSessionEventListener=WARN
 # Debug & Monitor Hibernate - END
 
 #logging.level.org.springframework.security=TRACE