Adding required structs and methods to get a list of publishers or subscribers with their respective qos

rmw/CMakeLists.txt

@@ -39,6 +39,7 @@ set(rmw_sources
   "src/validate_full_topic_name.c"
   "src/validate_namespace.c"
   "src/validate_node_name.c"
+  "src/topic_info_array.c"
 )
 set_source_files_properties(${rmw_sources} PROPERTIES LANGUAGE "C")
 add_library(${PROJECT_NAME} ${rmw_sources})

rmw/include/rmw/rmw.h

@@ -1109,6 +1109,70 @@ RMW_WARN_UNUSED
 rmw_ret_t
 rmw_set_log_severity(rmw_log_severity_t severity);
 
+/// Retrieves the information for all publishers to a given topic.
+/**
+ * The retrieved information will contain the publisher's node name, node namespace,
+ * associated topic type, gid and qos profile.
+ *
+ * The node parameter must not be `NULL` and must point to a valid node.
+ *
+ * The topic_name parameter must not be `NULL` and must follow the topic naming rules
+ * mentioned at http://design.ros2.org/articles/topic_and_service_names.html
+ * Non existent topic names are allowed. They will return an empty array.
+ *
+ * \param[in] node the handle to the node being used to query the ROS graph.
+ * \param[in] allocator the allocator to be used when allocating space for the array.
+ * \param[in] topic_name the name of the topic for which the list of publishers will be retrieved.
+ * \param[in] no_mangle if true, the topic name will not be mangled.
+ * \param[out] publishers_info an array of rmw_topic_info_t.
+ * \return `RMW_RET_OK` if the query was successful, or
+ * \return `RMW_RET_INVALID_ARGUMENT` if the node is invalid, or
+ * \return `RMW_RET_INVALID_ARGUMENT` if any arguments are invalid, or
+ * \return `RMW_RET_BAD_ALLOC` if memory allocation fails, or
+ * \return `RMW_RET_ERROR` if an unspecified error occurs.
+ */
+RMW_PUBLIC
+RMW_WARN_UNUSED
+rmw_ret_t
+rmw_get_publishers_info_by_topic(
+  const rmw_node_t * node,
+  rcutils_allocator_t * allocator,
+  const char * topic_name,
+  bool no_mangle,
+  rmw_topic_info_array_t * publishers_info);
+
+/// Retrieves the information for all subscriptions to a given topic.
+/**
+ * The retrieved information will contain the subscriptions's node name, node namespace,
+ * associated topic type, gid and qos profile.
+ *
+ * The node parameter must not be `NULL` and must point to a valid node.
+ *
+ * The topic_name parameter must not be `NULL` and must follow the topic naming rules
+ * mentioned at http://design.ros2.org/articles/topic_and_service_names.html
+ * Non existent topic names are allowed. They will return an empty array.
+ *
+ * \param[in] node the handle to the node being used to query the ROS graph.
+ * \param[in] allocator the allocator to be used when allocating space for the array.
+ * \param[in] topic_name the name of the topic for which the list of subscriptions will be retrieved.
+ * \param[in] no_mangle if true, the topic name will not be mangled.
+ * \param[out] subscriptions_info an array of rmw_topic_info_t..
+ * \return `RMW_RET_OK` if the query was successful, or
+ * \return `RMW_RET_INVALID_ARGUMENT` if the node is invalid, or
+ * \return `RMW_RET_INVALID_ARGUMENT` if any arguments are invalid, or
+ * \return `RMW_RET_BAD_ALLOC` if memory allocation fails, or
+ * \return `RMW_RET_ERROR` if an unspecified error occurs.
+ */
+RMW_PUBLIC
+RMW_WARN_UNUSED
+rmw_ret_t
+rmw_get_subscriptions_info_by_topic(
+  const rmw_node_t * node,
+  rcutils_allocator_t * allocator,
+  const char * topic_name,
+  bool no_mangle,
+  rmw_topic_info_array_t * subscriptions_info);
+
 #ifdef __cplusplus
 }
 #endif

rmw/include/rmw/topic_info_array.h

@@ -0,0 +1,85 @@
+// Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef RMW__TOPIC_INFO_ARRAY_H_
+#define RMW__TOPIC_INFO_ARRAY_H_
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+#include "rcutils/allocator.h"
+#include "rmw/types.h"
+#include "rmw/visibility_control.h"
+
+/// Return a rmw_topic_info_array_t struct with members initialized to `NULL`.
+RMW_PUBLIC
+RMW_WARN_UNUSED
+rmw_topic_info_array_t
+rmw_get_zero_initialized_topic_info_array(void);
+
+/// Check that a rmw_topic_info_array_t struct is zero initialized.
+RMW_PUBLIC
+RMW_WARN_UNUSED
+rmw_ret_t
+rmw_topic_info_array_check_zero(rmw_topic_info_array_t * topic_info_array);
+
+/// Initialize the info_array member inside rmw_topic_info_array_t with the given size
+/**
+ * The rmw_topic_info_array_t has a member variable info_array which is an array of
+ * type rmw_topic_info_t. This function allocates memory to this array to hold n elements,
+ * where n is the value of the size param to this function.
+ *
+ * \param[in] allocator the allocator to be used to allocate space
+ * \param[in] size the size of the array
+ * \param[out] topic_info_array the data structure to initialise
+ * \returns `RMW_RET_OK` on successful init, or
+ * \returns `RMW_RET_INVALID_ARGUMENT` if any of the parameters are NULL, or
+ * \returns `RMW_BAD_ALLOC` if memory allocation fails, or
+ * \returns `RMW_RET_ERROR` when an unspecified error occurs.
+ */
+RMW_PUBLIC
+RMW_WARN_UNUSED
+rmw_ret_t
+rmw_topic_info_array_init_with_size(
+  rcutils_allocator_t * allocator,
+  size_t size,
+  rmw_topic_info_array_t * topic_info_array);
+
+/// Finalize a rmw_topic_info_array_t object.
+/**
+ * The info_array member variable inside of rmw_topic_info_array represents an array of
+ * rmw_topic_info_t. When initializing this array, memory is allocated for it using the allocator.
+ * This function reclaims any allocated resources within the object and also sets the value of count
+ * to 0.
+ *
+ * \param[in] allocator the allocator used to allocate memory to the object
+ * \param[out] topic_info_array object to be finalized
+ * \returns `RMW_RET_OK` on successfully reclaiming memory, or
+ * \returns `RMW_RET_INVALID_ARGUMENT` if any parameters are NULL, or
+ * \returns `RMW_RET_ERROR` when an unspecified error occurs.
+ */
+RMW_PUBLIC
+RMW_WARN_UNUSED
+rmw_ret_t
+rmw_topic_info_array_fini(
+  rcutils_allocator_t * allocator,
+  rmw_topic_info_array_t * topic_info_array);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif    // RMW__TOPIC_INFO_ARRAY_H_

rmw/include/rmw/types.h

@@ -428,6 +428,31 @@ typedef struct RMW_PUBLIC_TYPE rmw_offered_deadline_missed_status_t
   int32_t total_count_change;
 } rmw_offered_deadline_missed_status_t;
 
+/// A Structure that encapsulates the name, namespace, topic_type, gid and qos_profile
+/// of publishers and subscriptions for a topic
+typedef struct RMW_PUBLIC_TYPE rmw_topic_info_t
+{
+  /// Name of the node
+  const char * node_name;
+  /// Namespace of the node
+  const char * node_namespace;
+  /// The associated TopicType
+  const char * topic_type;
+  /// The GID of the node
+  const char * gid;
+  /// Qos profile of the node
+  const rmw_qos_profile_t * qos_profile;
+} rmw_topic_info_t;
+
+/// Array of rmw_topic_info_t
+typedef struct RMW_PUBLIC_TYPE rmw_topic_info_array_t
+{
+  /// Size of the array.
+  size_t count;
+  /// Pointer representing an array of rmw_topic_info_t
+  rmw_topic_info_t * info_array;
+} rmw_topic_info_array_t;
+
 #ifdef __cplusplus
 }
 #endif

rmw/package.xml

@@ -20,6 +20,7 @@
   <test_depend>ament_cmake_gmock</test_depend>
   <test_depend>ament_lint_auto</test_depend>
   <test_depend>ament_lint_common</test_depend>
+  <test_depend>osrf_testing_tools_cpp</test_depend>
 
   <export>
     <build_type>ament_cmake</build_type>

rmw/src/topic_info_array.c

@@ -0,0 +1,89 @@
+// Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "rmw/topic_info_array.h"
+
+#include "rcutils/logging_macros.h"
+#include "rmw/error_handling.h"
+#include "rmw/convert_rcutils_ret_to_rmw_ret.h"
+#include "rmw/types.h"
+
+rmw_topic_info_array_t
+rmw_get_zero_initialized_topic_info_array(void)
+{
+  rmw_topic_info_array_t zero = {0};
+  return zero;
+}
+
+rmw_ret_t
+rmw_topic_info_array_check_zero(rmw_topic_info_array_t * topic_info_array)
+{
+  if (!topic_info_array) {
+    RMW_SET_ERROR_MSG("topic_info_array is null");
+    return RMW_RET_INVALID_ARGUMENT;
+  }
+  if (topic_info_array->count != 0 || topic_info_array->info_array != NULL) {
+    RMW_SET_ERROR_MSG("topic_info_array is not zeroed");
+    return RMW_RET_INVALID_ARGUMENT;
+  }
+  return RMW_RET_OK;
+}
+
+rmw_ret_t
+rmw_topic_info_array_init_with_size(
+  rcutils_allocator_t * allocator,
+  size_t size,
+  rmw_topic_info_array_t * topic_info_array)
+{
+  if (!allocator) {
+    RMW_SET_ERROR_MSG("allocator is null");
+    return RMW_RET_INVALID_ARGUMENT;
+  }
+  if (!topic_info_array) {
+    RMW_SET_ERROR_MSG("topic_info_array is null");
+    return RMW_RET_INVALID_ARGUMENT;
+  }
+  topic_info_array->info_array = allocator->allocate(sizeof(*topic_info_array->info_array) * size,
+      allocator->state);
+  if (!topic_info_array->info_array) {
+    RMW_SET_ERROR_MSG("failed to allocate memory for info_array");
+    return RMW_RET_BAD_ALLOC;
+  }
+  return RMW_RET_OK;
+}
+
+rmw_ret_t
+rmw_topic_info_array_fini(
+  rcutils_allocator_t * allocator,
+  rmw_topic_info_array_t * topic_info_array)
+{
+  if (!allocator) {
+    RMW_SET_ERROR_MSG("allocator is null");
+    return RMW_RET_INVALID_ARGUMENT;
+  }
+
+  if (!topic_info_array) {
+    RMW_SET_ERROR_MSG("topic_info_array is null");
+    return RMW_RET_INVALID_ARGUMENT;
+  }
+
+  if (!topic_info_array->info_array) {
+    RMW_SET_ERROR_MSG("invalid topic_info_array");
+    return RMW_RET_INVALID_ARGUMENT;
+  }
+  allocator->deallocate(topic_info_array->info_array, allocator->state);
+  topic_info_array->info_array = NULL;
+  topic_info_array->count = 0;
+  return RMW_RET_OK;
+}

rmw/test/CMakeLists.txt

@@ -1,4 +1,5 @@
 find_package(ament_cmake_gmock REQUIRED)
+find_package(osrf_testing_tools_cpp REQUIRED)
 
 ament_add_gmock(test_serialized_message
   test_serialized_message.cpp
@@ -41,3 +42,13 @@ if(TARGET test_validate_namespace)
     set_target_properties(test_validate_namespace PROPERTIES COMPILE_FLAGS "-std=c++14")
   endif()
 endif()
+
+ament_add_gmock(test_topic_info_array
+  test_topic_info_array.cpp
+  # Append the directory of librmw so it is found at test time.
+  APPEND_LIBRARY_DIRS "$<TARGET_FILE_DIR:${PROJECT_NAME}>"
+)
+if(TARGET test_topic_info_array)
+  target_link_libraries(test_topic_info_array ${PROJECT_NAME}
+  osrf_testing_tools_cpp::memory_tools)
+endif()

rmw/test/test_topic_info_array.cpp

@@ -0,0 +1,63 @@
+// Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "gmock/gmock.h"
+#include "osrf_testing_tools_cpp/scope_exit.hpp"
+#include "rcutils/allocator.h"
+
+#include "rmw/topic_info_array.h"
+#include "rmw/types.h"
+
+TEST(test_topic_info_array, zero_initialize) {
+  rmw_topic_info_array_t arr = rmw_get_zero_initialized_topic_info_array();
+  EXPECT_EQ(arr.count, 0u);
+  EXPECT_FALSE(arr.info_array);
+}
+
+TEST(test_topic_info_array, check_zero) {
+  rmw_topic_info_array_t arr = rmw_get_zero_initialized_topic_info_array();
+  EXPECT_EQ(rmw_topic_info_array_check_zero(&arr), RMW_RET_OK);
+  rmw_topic_info_array_t arr_count_not_zero = {1, nullptr};
+  EXPECT_EQ(rmw_topic_info_array_check_zero(&arr_count_not_zero), RMW_RET_INVALID_ARGUMENT);
+  rmw_topic_info_t topic_info;
+  rmw_topic_info_array_t arr_info_array_not_null = {1, &topic_info};
+  EXPECT_EQ(rmw_topic_info_array_check_zero(&arr_info_array_not_null), RMW_RET_INVALID_ARGUMENT);
+  EXPECT_EQ(rmw_topic_info_array_check_zero(nullptr), RMW_RET_INVALID_ARGUMENT);
+}
+
+TEST(test_topic_info_array, check_init_with_size) {
+  rcutils_allocator_t allocator = rcutils_get_default_allocator();
+  rmw_topic_info_array_t arr = rmw_get_zero_initialized_topic_info_array();
+  OSRF_TESTING_TOOLS_CPP_SCOPE_EXIT({
+    rmw_ret_t fini_ret = rmw_topic_info_array_fini(&allocator, &arr);
+    EXPECT_EQ(fini_ret, RMW_RET_OK);
+  });
+  EXPECT_EQ(rmw_topic_info_array_init_with_size(nullptr, 1, &arr), RMW_RET_INVALID_ARGUMENT);
+  EXPECT_EQ(rmw_topic_info_array_init_with_size(&allocator, 1, nullptr), RMW_RET_INVALID_ARGUMENT);
+  EXPECT_FALSE(arr.info_array);
+  rmw_ret_t ret = rmw_topic_info_array_init_with_size(&allocator, 5, &arr);
+  EXPECT_EQ(ret, RMW_RET_OK);
+  EXPECT_TRUE(arr.info_array);
+}
+
+TEST(test_topic_info_array, check_fini) {
+  rcutils_allocator_t allocator = rcutils_get_default_allocator();
+  rmw_topic_info_array_t arr = rmw_get_zero_initialized_topic_info_array();
+  rmw_ret_t ret = rmw_topic_info_array_init_with_size(&allocator, 5, &arr);
+  EXPECT_EQ(ret, RMW_RET_OK);
+  EXPECT_TRUE(arr.info_array);
+  ret = rmw_topic_info_array_fini(&allocator, &arr);
+  EXPECT_EQ(ret, RMW_RET_OK);
+  EXPECT_FALSE(arr.info_array);
+}