Log error if calls to dispose fail (osrf#40)

In these cases, we are likely leaking memory.

Signed-off-by: Jacob Perron <[email protected]>

Author: jacobperron

rcljava/src/main/java/org/ros2/rcljava/client/ClientImpl.java

@@ -135,11 +135,13 @@ public final Class<MessageDefinition> getResponseType() {
    */
   public final void dispose() {
     Node node = this.nodeReference.get();
-    if (node != null) {
-      node.removeClient(this);
-      nativeDispose(node.getHandle(), this.handle);
-      this.handle = 0;
+    if (node == null) {
+      logger.error("Node reference is null. Failed to dispose of Client.");
+      return;
     }
+    node.removeClient(this);
+    nativeDispose(node.getHandle(), this.handle);
+    this.handle = 0;
   }
 
   /**

rcljava/src/main/java/org/ros2/rcljava/publisher/PublisherImpl.java

@@ -187,10 +187,12 @@ public final void dispose() {
     }
     this.eventHandlers.clear();
     Node node = this.nodeReference.get();
-    if (node != null) {
-      node.removePublisher(this);
-      nativeDispose(node.getHandle(), this.handle);
-      this.handle = 0;
+    if (node == null) {
+      logger.error("Node reference is null. Failed to dispose of Publisher.");
+      return;
     }
+    node.removePublisher(this);
+    nativeDispose(node.getHandle(), this.handle);
+    this.handle = 0;
   }
 }

rcljava/src/main/java/org/ros2/rcljava/service/ServiceImpl.java

@@ -84,11 +84,13 @@ public final Class<MessageDefinition> getResponseType() {
    */
   public final void dispose() {
     Node node = this.nodeReference.get();
-    if (node != null) {
-      node.removeService(this);
-      nativeDispose(node.getHandle(), this.handle);
-      this.handle = 0;
+    if (node == null) {
+      logger.error("Node reference is null. Failed to dispose of Service.");
+      return;
     }
+    node.removeService(this);
+    nativeDispose(node.getHandle(), this.handle);
+    this.handle = 0;
   }
 
   /**

rcljava/src/main/java/org/ros2/rcljava/subscription/SubscriptionImpl.java

@@ -200,11 +200,13 @@ public final void dispose() {
     }
     this.eventHandlers.clear();
     Node node = this.nodeReference.get();
-    if (node != null) {
-      node.removeSubscription(this);
-      nativeDispose(node.getHandle(), this.handle);
-      this.handle = 0;
+    if (node == null) {
+      logger.error("Node reference is null. Failed to dispose of Subscription.");
+      return;
     }
+    node.removeSubscription(this);
+    nativeDispose(node.getHandle(), this.handle);
+    this.handle = 0;
   }
 
   public void executeCallback(T message) {