Minor change, just added MapDB groovy toy script

broker/src/main/java/org/eclipse/moquette/spi/persistence/MapDBPersistentStore.java

@@ -84,7 +84,7 @@ public class MapDBPersistentStore implements IMessagesStore, ISessionsStore {
 	            LOG.error(null, ex);
 	            throw new MQTTException("Can't create temp file for subscriptions storage [" + m_storePath + "]", ex);
 	        }
-	        m_db = DBMaker.newFileDB(tmpFile).make();
+	        m_db = DBMaker.newFileDB(tmpFile).closeOnJvmShutdown().make();
     	}
         m_retainedStore = m_db.getHashMap("retained");
         m_persistentMessageStore = m_db.getHashMap("persistedMessages");

tools_scripts/mapdbWalTest.groovy

@@ -0,0 +1,43 @@
+@Grab(group='org.mapdb', module='mapdb', version='1.0.8')
+import org.mapdb.DB
+import org.mapdb.DBMaker
+
+class User implements Serializable {
+    String name
+    String surname
+}
+
+def writeSomeData(Map m) {
+    m.put(1, new User(name: "mario", surname: "rossi"))
+    m.put(2, new User(name: "gianni", surname: "bianchi"))
+    m.put(3, new User(name: "pino", surname: "verdi"))
+}
+
+def readSomeData(Map m) {
+    m.each {k, v ->
+        println "id: $k, value: $v"
+    }
+}
+
+if (args.size() != 1) {
+    println "groovy mapdbWalTest.groovy [writer|reader]"
+    exit 1
+}
+
+String mode = args[0]
+File tmpFile = new File("test_store.mapdb")
+tmpFile.createNewFile()
+DB db = DBMaker.newFileDB(tmpFile).make()
+Map mapStore = db.getHashMap("storageMap")
+
+switch (mode) {
+    case "writer":
+        writeSomeData(mapStore)
+        db.commit()
+        return
+    case "reader":
+        readSomeData(mapStore)
+        return
+    default:
+        println "Error option not recognized must be one of [writer|reader]"
+}