Exposing the 'resubscribe' method, which allows to re-establish a subscription after it was cancelled

graphenej/src/main/java/de/bitsharesmunich/graphenej/api/SubscriptionMessagesHub.java

@@ -142,12 +142,7 @@ public class SubscriptionMessagesHub extends BaseGrapheneHandler implements Subs
             WitnessResponse<Integer> witnessResponse = gson.fromJson(message, ApiIdResponse);
             databaseApiId = witnessResponse.result;
 
-            ArrayList<Serializable> subscriptionParams = new ArrayList<>();
-            subscriptionParams.add(String.format("%d", SUBCRIPTION_NOTIFICATION));
-            subscriptionParams.add(clearFilter);
-            ApiCall getDatabaseId = new ApiCall(databaseApiId, RPC.CALL_SET_SUBSCRIBE_CALLBACK, subscriptionParams, RPC.VERSION, SUBCRIPTION_REQUEST);
-            websocket.sendText(getDatabaseId.toJsonString());
-            currentId++;
+            subscribe();
         } else if(currentId == SUBCRIPTION_REQUEST){
             List<SubscriptionListener> subscriptionListeners = mSubscriptionDeserializer.getSubscriptionListeners();
 
@@ -192,26 +187,65 @@ public class SubscriptionMessagesHub extends BaseGrapheneHandler implements Subs
         System.out.println(">> "+frame.getPayloadText());
     }
 
+    /**
+     * Private method that sends a subscription request to the full node
+     */
+    private void subscribe(){
+        ArrayList<Serializable> subscriptionParams = new ArrayList<>();
+        subscriptionParams.add(String.format("%d", SUBCRIPTION_NOTIFICATION));
+        subscriptionParams.add(clearFilter);
+        ApiCall getDatabaseId = new ApiCall(databaseApiId, RPC.CALL_SET_SUBSCRIBE_CALLBACK, subscriptionParams, RPC.VERSION, SUBCRIPTION_REQUEST);
+        mWebsocket.sendText(getDatabaseId.toJsonString());
+        currentId = SUBCRIPTION_REQUEST;
+    }
+
+    /**
+     * Public method used to re-establish a subscription after it was cancelled by a previous
+     * call to the {@see #cancelSubscriptions()} method call.
+     */
+    public void resubscribe(){
+        if(mWebsocket.isOpen()){
+            subscribe();
+        }else{
+            throw new IllegalStateException("Websocket is not open, can't resubscribe");
+        }
+    }
+
+    /**
+     * Method that send a subscription cancellation request to the full node, and also
+     * deregisters all subscription and request listeners.
+     */
+    public void cancelSubscriptions(){
+        ApiCall unsubscribe = new ApiCall(databaseApiId, RPC.CALL_CANCEL_ALL_SUBSCRIPTIONS, new ArrayList<Serializable>(), RPC.VERSION, SUBCRIPTION_REQUEST);
+        mWebsocket.sendText(unsubscribe.toJsonString());
+
+        // Clearing all subscription listeners
+        mSubscriptionDeserializer.clearAllSubscriptionListeners();
+
+        // Clearing all request handler listners
+        mHandlerMap.clear();
+    }
+
+    /**
+     * Method used to reset all internal variables.
+     */
     public void reset(){
         currentId = 0;
         databaseApiId = -1;
         subscriptionCounter = 0;
     }
 
-    public void cancelSubscriptions(){
-        ApiCall unsubscribe = new ApiCall(databaseApiId, RPC.CALL_CANCEL_ALL_SUBSCRIPTIONS, new ArrayList<Serializable>(), RPC.VERSION, SUBCRIPTION_REQUEST);
-        mWebsocket.sendText(unsubscribe.toJsonString());
-    }
-
     public void addRequestHandler(BaseGrapheneHandler handler) throws RepeatedRequestIdException {
         if(mHandlerMap.get(handler.getRequestId()) != null){
             throw new RepeatedRequestIdException("Already registered handler with id: "+handler.getRequestId());
         }
 
-        System.out.println("Registering handler with id: "+handler.getRequestId());
         mHandlerMap.put(handler.getRequestId(), handler);
 
         try {
+            // Artificially calling the 'onConnected' method of the handler.
+            // The underlying websocket was already connected, but from the WebSocketAdapter
+            // point of view it doesn't make a difference.
             handler.onConnected(mWebsocket, null);
         } catch (Exception e) {
             System.out.println("Exception. Msg: "+e.getMessage());

graphenej/src/main/java/de/bitsharesmunich/graphenej/models/SubscriptionResponse.java

@@ -56,7 +56,7 @@ public class SubscriptionResponse {
     public List<Serializable> params;
 
     /**
-     * Deserializer class that is used to parse and deserialize subscription responses in a partial way,
+     * Inner static class used to parse and deserialize subscription responses in a partial way,
      * depending on the amount of SubscriptionListeners we might have registered.
      *
      * The rationale behind these architecture is to avoid wasting computational resources parsing unneeded
@@ -83,6 +83,11 @@ public class SubscriptionResponse {
             listenerTypeCount = new HashMap<>();
         }
 
+        /**
+         * Adds a subscription listener to the list.
+         * @param subscriptionListener: Class implementing the {@see SubscriptionListener} interface
+         *                            to be added to the list.
+         */
         public void addSubscriptionListener(SubscriptionListener subscriptionListener){
             int currentCount = 0;
             if(listenerTypeCount.containsKey(subscriptionListener.getInterestObjectType())){
@@ -92,10 +97,19 @@ public class SubscriptionResponse {
             this.mListeners.add(subscriptionListener);
         }
 
+        /**
+         * Retrieves the full list of SubscriptionListeners registered.
+         * @return
+         */
         public List<SubscriptionListener> getSubscriptionListeners(){
             return this.mListeners;
         }
 
+        /**
+         * Removes a subscription listener to the list.
+         * @param subscriptionListener: Class implementing the {@see SubscriptionListener} interface
+         *                            to be removed from the list.
+         */
         public void removeSubscriptionListener(SubscriptionListener subscriptionListener){
             int currentCount = listenerTypeCount.get(subscriptionListener.getInterestObjectType());
             if(currentCount != 0){
@@ -106,6 +120,14 @@ public class SubscriptionResponse {
             this.mListeners.remove(subscriptionListener);
         }
 
+        /**
+         * Removes all registered subscription listeners
+         */
+        public void clearAllSubscriptionListeners(){
+            this.mListeners.clear();
+            this.listenerTypeCount.clear();
+        }
+
         @Override
         public SubscriptionResponse deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {
             SubscriptionResponse response = new SubscriptionResponse();

graphenej/src/test/java/de/bitsharesmunich/graphenej/api/SubscriptionMessagesHubTest.java

@@ -56,6 +56,14 @@ public class SubscriptionMessagesHubTest extends BaseApiTest {
             }
         };
 
+        TimerTask resubscribeTask = new TimerTask() {
+            @Override
+            public void run() {
+                System.out.println("Resubscribing..");
+                mMessagesHub.resubscribe();
+            }
+        };
+
         /**
          * Task that will just finish the test.
          */
@@ -77,7 +85,8 @@ public class SubscriptionMessagesHubTest extends BaseApiTest {
 
             Timer timer = new Timer();
             timer.schedule(unsubscribeTask, 5000);
-            timer.schedule(shutdownTask, 15000);
+            timer.schedule(resubscribeTask, 10000);
+            timer.schedule(shutdownTask, 20000);
 
             // Holding this thread while we get update notifications
             synchronized (this){