Fixed issue #25 due to bad packetID generation

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

@@ -199,7 +199,7 @@ public class MapDBPersistentStore implements IMessagesStore, ISessionsStore {
     }
 
     /**
-     * Return the next valid packetIdentifer for the given client session.
+     * Return the next valid packetIdentifier for the given client session.
      * */
     @Override
     public int nextPacketID(String clientID) {
@@ -211,7 +211,7 @@ public class MapDBPersistentStore implements IMessagesStore, ISessionsStore {
             this.m_inFlightIds.put(clientID, inFlightForClient);
             return nextPacketId;
         }
-        int maxId = Collections.max(inFlightForClient);
+        int maxId = inFlightForClient.isEmpty() ? 0 : Collections.max(inFlightForClient);
         int nextPacketId = (maxId + 1) % 0xFFFF;
         inFlightForClient.add(nextPacketId);
         return nextPacketId;

broker/src/test/java/org/eclipse/moquette/spi/impl/MapDBPersistentStoreTest.java

@@ -38,7 +38,6 @@ public class MapDBPersistentStoreTest {
         
     @Before
     public void setUp() throws Exception {
-    	    	
         File dbFile = new File(DEFAULT_PERSISTENT_PATH);
         assertFalse(String.format("The DB storagefile %s already exists", DEFAULT_PERSISTENT_PATH), dbFile.exists());
         
@@ -72,4 +71,35 @@ public class MapDBPersistentStoreTest {
         Subscription sub = subscriptions.get(0);
         assertEquals(overrindingSubscription.getRequestedQos(), sub.getRequestedQos());
     }
+
+    @Test
+    public void testNextPacketID_notExistingClientSession() {
+        int packetId = m_storageService.nextPacketID("NOT_EXISTING_CLI");
+        assertEquals(1, packetId);
+    }
+
+    @Test
+    public void testNextPacketID_existingClientSession() {
+        //Force creation of inflight map for the CLIENT session
+        int packetId = m_storageService.nextPacketID("CLIENT");
+        assertEquals(1, packetId);
+
+        //request a second packetID
+        packetId = m_storageService.nextPacketID("CLIENT");
+        assertEquals(2, packetId);
+    }
+
+    @Test
+    public void testNextPacketID() {
+        //request a first ID
+        int packetId = m_storageService.nextPacketID("CLIENT");
+        assertEquals(1, packetId);
+
+        //release the ID
+        m_storageService.cleanInFlight("CLIENT", packetId);
+
+        //request a second packetID, counter restarts from 0
+        packetId = m_storageService.nextPacketID("CLIENT");
+        assertEquals(1, packetId);
+    }
 }