Add getSubscriptionsInfo to Node class (osrf#27)

Signed-off-by: Ivan Santiago Paunovic <ivanpauno@ekumenlabs.com>

Author: ivanpauno

rcljava/include/org_ros2_rcljava_node_NodeImpl.h

@@ -119,6 +119,15 @@ JNIEXPORT void
 JNICALL Java_org_ros2_rcljava_node_NodeImpl_nativeGetPublishersInfo(
   JNIEnv *, jclass, jlong, jstring, jobject);
 
+/*
+ * Class:     org_ros2_rcljava_node_NodeImpl
+ * Method:    nativeGetSubscriptionsInfo
+ * Signature: (JLjava/lang/String;Ljava/util/List;)V
+ */
+JNIEXPORT void
+JNICALL Java_org_ros2_rcljava_node_NodeImpl_nativeGetSubscriptionsInfo(
+  JNIEnv *, jclass, jlong, jstring, jobject);
+
 #ifdef __cplusplus
 }
 #endif

rcljava/src/main/cpp/org_ros2_rcljava_node_NodeImpl.cpp

@@ -379,9 +379,10 @@ Java_org_ros2_rcljava_node_NodeImpl_nativeGetTopicNamesAndTypes(
   }
 }
 
-JNIEXPORT void JNICALL
-Java_org_ros2_rcljava_node_NodeImpl_nativeGetPublishersInfo(
-  JNIEnv * env, jclass, jlong handle, jstring jtopic_name, jobject jpublishers_info)
+template<typename FunctorT>
+void
+get_endpoint_info_common(
+  JNIEnv * env, jlong handle, jstring jtopic_name, jobject jendpoints_info, FunctorT get_info)
 {
   rcl_node_t * node = reinterpret_cast<rcl_node_t *>(handle);
   if (!node) {
@@ -391,7 +392,7 @@ Java_org_ros2_rcljava_node_NodeImpl_nativeGetPublishersInfo(
   }
 
   rcutils_allocator_t allocator = rcutils_get_default_allocator();
-  rcl_topic_endpoint_info_array_t publishers_info =
+  rcl_topic_endpoint_info_array_t endpoints_info =
     rcl_get_zero_initialized_topic_endpoint_info_array();
 
   const char * topic_name = env->GetStringUTFChars(jtopic_name, NULL);
@@ -401,26 +402,26 @@ Java_org_ros2_rcljava_node_NodeImpl_nativeGetPublishersInfo(
     return;
   }
 
-  rcl_ret_t ret = rcl_get_publishers_info_by_topic(
+  rcl_ret_t ret = get_info(
     node,
     &allocator,
     topic_name,
     false,  // use ros mangling conventions
-    &publishers_info);
+    &endpoints_info);
 
   env->ReleaseStringUTFChars(jtopic_name, topic_name);
 
   RCLJAVA_COMMON_THROW_FROM_RCL(env, ret, "failed to get publisher info");
   auto cleanup_info_array = rcpputils::make_scope_exit(
-    [info_ptr = &publishers_info, allocator_ptr = &allocator, env]() {
+    [info_ptr = &endpoints_info, allocator_ptr = &allocator, env]() {
       rcl_ret_t ret = rcl_topic_endpoint_info_array_fini(info_ptr, allocator_ptr);
       if (!env->ExceptionCheck() && RCL_RET_OK != ret) {
-        rcljava_throw_rclexception(env, ret, "failed to destroy rcl publisher info");
+        rcljava_throw_rclexception(env, ret, "failed to destroy rcl endpoints info");
       }
     }
   );
 
-  jclass list_clazz = env->GetObjectClass(jpublishers_info);
+  jclass list_clazz = env->GetObjectClass(jendpoints_info);
   jmethodID list_add_mid = env->GetMethodID(list_clazz, "add", "(Ljava/lang/Object;)Z");
   RCLJAVA_COMMON_CHECK_FOR_EXCEPTION(env);
   jclass endpoint_info_clazz = env->FindClass("org/ros2/rcljava/graph/EndpointInfo");
@@ -431,13 +432,29 @@ Java_org_ros2_rcljava_node_NodeImpl_nativeGetPublishersInfo(
     endpoint_info_clazz, "nativeFromRCL", "(J)V");
   RCLJAVA_COMMON_CHECK_FOR_EXCEPTION(env);
 
-  for (size_t i = 0; i < publishers_info.size; i++) {
+  for (size_t i = 0; i < endpoints_info.size; i++) {
     jobject item = env->NewObject(endpoint_info_clazz, endpoint_info_init_mid);
     RCLJAVA_COMMON_CHECK_FOR_EXCEPTION(env);
-    env->CallVoidMethod(item, endpoint_info_from_rcl_mid, &publishers_info.info_array[i]);
+    env->CallVoidMethod(item, endpoint_info_from_rcl_mid, &endpoints_info.info_array[i]);
     RCLJAVA_COMMON_CHECK_FOR_EXCEPTION(env);
-    env->CallBooleanMethod(jpublishers_info, list_add_mid, item);
+    env->CallBooleanMethod(jendpoints_info, list_add_mid, item);
     RCLJAVA_COMMON_CHECK_FOR_EXCEPTION(env);
     env->DeleteLocalRef(item);
   }
 }
+
+JNIEXPORT void JNICALL
+Java_org_ros2_rcljava_node_NodeImpl_nativeGetPublishersInfo(
+  JNIEnv * env, jclass, jlong handle, jstring jtopic_name, jobject jpublishers_info)
+{
+  get_endpoint_info_common(
+    env, handle, jtopic_name, jpublishers_info, rcl_get_publishers_info_by_topic);
+}
+
+JNIEXPORT void JNICALL
+Java_org_ros2_rcljava_node_NodeImpl_nativeGetSubscriptionsInfo(
+  JNIEnv * env, jclass, jlong handle, jstring jtopic_name, jobject jsubscriptions_info)
+{
+  get_endpoint_info_common(
+    env, handle, jtopic_name, jsubscriptions_info, rcl_get_subscriptions_info_by_topic);
+}

rcljava/src/main/java/org/ros2/rcljava/node/Node.java

@@ -578,4 +578,16 @@ <T extends ServiceDefinition> Client<T> createClient(final Class<T> serviceType,
    *    passed topic.
    */
   Collection<EndpointInfo> getPublishersInfo(final String topicName);
+
+  /**
+   * Get information of all subscriptions in a topic.
+   *
+   * The queried information includes the node that created the publisher, its qos, etc.
+   * For more info, see @{link EndpointInfo}.
+   *
+   * @param topicName The topic name of interest.
+   * @return A collection of `EndpointInfo` instances, describing all subscriptions in the
+   *    passed topic.
+   */
+  Collection<EndpointInfo> getSubscriptionsInfo(final String topicName);
 }

rcljava/src/main/java/org/ros2/rcljava/node/NodeImpl.java

@@ -782,4 +782,13 @@ public final Collection<EndpointInfo> getPublishersInfo(final String topicName)
 
   private native static final void nativeGetPublishersInfo(
     final long handle, final String topicName, ArrayList<EndpointInfo> endpointInfo);
+  
+  public final Collection<EndpointInfo> getSubscriptionsInfo(final String topicName) {
+    ArrayList<EndpointInfo> returnValue = new ArrayList();
+    nativeGetSubscriptionsInfo(this.handle, topicName, returnValue);
+    return returnValue;
+  }
+
+  private native static final void nativeGetSubscriptionsInfo(
+    final long handle, final String topicName, ArrayList<EndpointInfo> endpointInfo);
 }

rcljava/src/test/java/org/ros2/rcljava/node/NodeTest.java

@@ -1064,4 +1064,61 @@ public void accept(final Collection<EndpointInfo> info) {
     publisher.dispose();
     publisher2.dispose();
   }
-}
+
+  @Test
+  public final void testGetSubscriptionsInfo() {
+    Subscription<rcljava.msg.UInt32> subscription = node.<rcljava.msg.UInt32>createSubscription(
+      rcljava.msg.UInt32.class, "test_get_subscriptions_info", new Consumer<rcljava.msg.UInt32>() {
+        public void accept(final rcljava.msg.UInt32 msg) {}
+      });
+    Subscription<rcljava.msg.UInt32> subscription2 = node.<rcljava.msg.UInt32>createSubscription(
+      rcljava.msg.UInt32.class, "test_get_subscriptions_info", new Consumer<rcljava.msg.UInt32>() {
+        public void accept(final rcljava.msg.UInt32 msg) {}
+      }, QoSProfile.sensorData());
+
+    Consumer<Collection<EndpointInfo>> validateEndpointInfo =
+    new Consumer<Collection<EndpointInfo>>() {
+      public void accept(final Collection<EndpointInfo> info) {
+        assertEquals(info.size(), 2);
+        Iterator<EndpointInfo> it = info.iterator();
+        EndpointInfo item = it.next();
+        assertEquals("test_node", item.nodeName);
+        assertEquals("/", item.nodeNamespace);
+        assertEquals("rcljava/msg/UInt32", item.topicType);
+        assertEquals(item.endpointType, EndpointInfo.EndpointType.SUBSCRIPTION);
+        assertEquals(item.qos.getReliability(), Reliability.RELIABLE);
+        item = it.next();
+        assertEquals("test_node", item.nodeName);
+        assertEquals("/", item.nodeNamespace);
+        assertEquals("rcljava/msg/UInt32", item.topicType);
+        assertEquals(item.endpointType, EndpointInfo.EndpointType.SUBSCRIPTION);
+        assertEquals(item.qos.getReliability(), Reliability.BEST_EFFORT);
+        assertFalse(it.hasNext());
+      }
+    };
+
+    long start = System.currentTimeMillis();
+    boolean ok = false;
+    Collection<EndpointInfo> subscriptionsInfo = null;
+    do {
+      subscriptionsInfo = node.getSubscriptionsInfo("/test_get_subscriptions_info");
+      try {
+        validateEndpointInfo.accept(subscriptionsInfo);
+        ok = true;
+      } catch (AssertionError err) {
+        // ignore here, it's going to be validated again at the end.
+      }
+      // TODO(ivanpauno): We could wait for the graph guard condition to be triggered if that
+      // would be available.
+      try {
+        TimeUnit.MILLISECONDS.sleep(100);
+      } catch (InterruptedException err) {
+        // ignore
+      }
+    } while (!ok && System.currentTimeMillis() < start + 1000);
+    assertNotNull(subscriptionsInfo);
+    validateEndpointInfo.accept(subscriptionsInfo);
+    subscription.dispose();
+    subscription2.dispose();
+  }
+}