Removed TreeNode's parent reference to avoid maintaning a reference that could keep live big trees (solves #119 and #126)

broker/src/main/java/io/moquette/spi/impl/subscriptions/SubscriptionsStore.java

@@ -90,7 +90,7 @@ public class SubscriptionsStore {
         }
     }
     
-    private AtomicReference<TreeNode> subscriptions = new AtomicReference<>(new TreeNode(null));
+    private AtomicReference<TreeNode> subscriptions = new AtomicReference<>(new TreeNode());
     private static final Logger LOG = LoggerFactory.getLogger(SubscriptionsStore.class);
 
     /**
@@ -109,8 +109,8 @@ public class SubscriptionsStore {
             LOG.debug("Re-subscribing {} to topic {}", subscription.getClientId(), subscription.getTopicFilter());
             add(subscription);
         }
-        if (LOG.isDebugEnabled()) {
-            LOG.debug("Finished loading. Subscription tree after {}", dumpTree());
+        if (LOG.isTraceEnabled()) {
+            LOG.trace("Finished loading. Subscription tree after {}", dumpTree());
         }
     }
 
@@ -146,13 +146,13 @@ public class SubscriptionsStore {
             if ((matchingChildren = current.childWithToken(token)) != null) {
                 //copy the traversed node
                 current = matchingChildren.copy();
-                current.m_parent = parent;
+//                current.m_parent = parent;
                 //update the child just added in the children list
                 parent.updateChild(matchingChildren, current);
                 parent = current;
             } else {
                 //create a new node for the newly inserted token
-                matchingChildren = new TreeNode(current);
+                matchingChildren = new TreeNode(/*current*/);
                 matchingChildren.setToken(token);
                 current.addChild(matchingChildren);
                 current = matchingChildren;

broker/src/main/java/io/moquette/spi/impl/subscriptions/TreeNode.java

@@ -28,13 +28,11 @@ class TreeNode {
         
     }
 
-    TreeNode m_parent;
     Token m_token;
     List<TreeNode> m_children = new ArrayList<>();
     List<Subscription> m_subscriptions = new ArrayList<>();
 
-    TreeNode(TreeNode parent) {
-        this.m_parent = parent;
+    TreeNode() {
     }
 
     Token getToken() {
@@ -70,13 +68,9 @@ class TreeNode {
      * Copy the token and the children.
      * */
     TreeNode copy() {
-        final TreeNode copy = new TreeNode(this);
-        copy.m_parent = m_parent;
+        final TreeNode copy = new TreeNode();
         copy.m_children = new ArrayList<>(m_children);
-        copy.m_subscriptions = new ArrayList<>(m_subscriptions.size());
-        for (Subscription sub : m_subscriptions) {
-            copy.m_subscriptions.add(new Subscription(sub));
-        }
+        copy.m_subscriptions = new ArrayList<>(m_subscriptions);
         copy.m_token = m_token;
         return copy;
     }

broker/src/test/java/io/moquette/spi/impl/subscriptions/SubscriptionsStoreTest.java

@@ -404,7 +404,7 @@ public class SubscriptionsStoreTest {
 
     @Test
     public void testRecreatePath_emptyRoot() {
-        TreeNode oldRoot = new TreeNode(null);
+        TreeNode oldRoot = new TreeNode();
         final SubscriptionsStore.NodeCouple resp = store.recreatePath("/finance", oldRoot);
 
         //Verify
@@ -416,7 +416,7 @@ public class SubscriptionsStoreTest {
 
     @Test
     public void testRecreatePath_1layer_tree() {
-        TreeNode oldRoot = new TreeNode(null);
+        TreeNode oldRoot = new TreeNode();
         final SubscriptionsStore.NodeCouple respFinance = store.recreatePath("/finance", oldRoot);
         final SubscriptionsStore.NodeCouple respPlus = store.recreatePath("/+", respFinance.root);
 

broker/src/test/java/io/moquette/spi/impl/subscriptions/TreeNodeTest.java

@@ -13,7 +13,7 @@ public class TreeNodeTest {
 
     @Test
     public void testAddSubscriptionOverwriteAnExistingWithDifferentCleanSessionFlag() throws Exception {
-        TreeNode root = new TreeNode(null);
+        TreeNode root = new TreeNode();
         Subscription existingSub = new Subscription(CLIENT_ID, "/topic", LEAST_ONE, false);
         root.addSubscription(existingSub);
         Set<Subscription> subs = root.findAllByClientID(CLIENT_ID);