Methods to retrieve matched counts on pub/sub.

rcl/include/rcl/publisher.h

@@ -397,6 +397,33 @@ RCL_PUBLIC
 bool
 rcl_publisher_is_valid(const rcl_publisher_t * publisher);
 
+/// Get the number of subscriptions matched to a publisher.
+/**
+ * Used to get the internal count of subscriptions matched to a publisher.
+ *
+ * <hr>
+ * Attribute          | Adherence
+ * ------------------ | -------------
+ * Allocates Memory   | No
+ * Thread-Safe        | Yes
+ * Uses Atomics       | Maybe [1]
+ * Lock-Free          | Maybe [1]
+ * <i>[1] only if the underlying rmw doesn't make use of this feature </i>
+ *
+ * \param[in] publisher pointer to the rcl publisher
+ * \param[out] subscription_count number of matched subscriptions
+ * \return `RCL_RET_OK` if the count was retrieved, or
+ * \return `RCL_RET_INVALID_ARGUMENT` if any arguments are invalid, or
+ * \return `RCL_RET_SUBSCRIPTION_INVALID` if the subscription is invalid, or
+ * \return `RCL_RET_ERROR` if an unspecified error occurs.
+ */
+RCL_PUBLIC
+RCL_WARN_UNUSED
+rmw_ret_t
+rcl_publisher_get_subscription_count(
+  const rcl_publisher_t * publisher,
+  size_t * subscription_count);
+
 #ifdef __cplusplus
 }
 #endif

rcl/include/rcl/subscription.h

@@ -407,6 +407,33 @@ RCL_PUBLIC
 bool
 rcl_subscription_is_valid(const rcl_subscription_t * subscription);
 
+/// Get the number of publishers matched to a subscription.
+/**
+ * Used to get the internal count of publishers matched to a subscription.
+ *
+ * <hr>
+ * Attribute          | Adherence
+ * ------------------ | -------------
+ * Allocates Memory   | No
+ * Thread-Safe        | Yes
+ * Uses Atomics       | Maybe [1]
+ * Lock-Free          | Maybe [1]
+ * <i>[1] only if the underlying rmw doesn't make use of this feature </i>
+ *
+ * \param[in] subscription pointer to the rcl subscription
+ * \param[out] publisher_count number of matched publishers
+ * \return `RCL_RET_OK` if the count was retrieved, or
+ * \return `RCL_RET_INVALID_ARGUMENT` if any arguments are invalid, or
+ * \return `RCL_RET_SUBSCRIPTION_INVALID` if the subscription is invalid, or
+ * \return `RCL_RET_ERROR` if an unspecified error occurs.
+ */
+RCL_PUBLIC
+RCL_WARN_UNUSED
+rmw_ret_t
+rcl_subscription_get_publisher_count(
+  const rcl_subscription_t * subscription,
+  size_t * publisher_count);
+
 #ifdef __cplusplus
 }
 #endif

rcl/src/rcl/publisher.c

@@ -22,6 +22,7 @@ extern "C"
 #include <stdio.h>
 #include <string.h>
 
+#include "common.h"
 #include "rcl/allocator.h"
 #include "rcl/error_handling.h"
 #include "rcl/expand_topic_name.h"
@@ -302,6 +303,26 @@ rcl_publisher_is_valid(const rcl_publisher_t * publisher)
   return true;
 }
 
+rmw_ret_t
+rcl_publisher_get_subscription_count(
+  const rcl_publisher_t * publisher,
+  size_t * subscription_count)
+{
+  if (!rcl_publisher_is_valid(publisher)) {
+    return RCL_RET_PUBLISHER_INVALID;
+  }
+  RCL_CHECK_ARGUMENT_FOR_NULL(subscription_count, RCL_RET_INVALID_ARGUMENT);
+
+  rmw_ret_t ret = rmw_publisher_count_matched_subscriptions(publisher->impl->rmw_handle,
+      subscription_count);
+
+  if (ret != RMW_RET_OK) {
+    RCL_SET_ERROR_MSG(rmw_get_error_string().str);
+    return rcl_convert_rmw_ret_to_rcl_ret(ret);
+  }
+  return RCL_RET_OK;
+}
+
 #ifdef __cplusplus
 }
 #endif

rcl/src/rcl/subscription.c

@@ -21,6 +21,7 @@ extern "C"
 
 #include <stdio.h>
 
+#include "common.h"
 #include "rcl/error_handling.h"
 #include "rcl/expand_topic_name.h"
 #include "rcl/remap.h"
@@ -337,6 +338,25 @@ rcl_subscription_is_valid(const rcl_subscription_t * subscription)
   return true;
 }
 
+rmw_ret_t
+rcl_subscription_get_publisher_count(
+  const rcl_subscription_t * subscription,
+  size_t * publisher_count)
+{
+  if (!rcl_subscription_is_valid(subscription)) {
+    return RCL_RET_SUBSCRIPTION_INVALID;
+  }
+  RCL_CHECK_ARGUMENT_FOR_NULL(publisher_count, RCL_RET_INVALID_ARGUMENT);
+  rmw_ret_t ret = rmw_subscription_count_matched_publishers(subscription->impl->rmw_handle,
+      publisher_count);
+
+  if (ret != RMW_RET_OK) {
+    RCL_SET_ERROR_MSG(rmw_get_error_string().str);
+    return rcl_convert_rmw_ret_to_rcl_ret(ret);
+  }
+  return RCL_RET_OK;
+}
+
 #ifdef __cplusplus
 }
 #endif

rcl/test/CMakeLists.txt

@@ -102,6 +102,15 @@ function(test_target_function)
     ${SKIP_TEST}
   )
 
+  rcl_add_custom_gtest(test_count_matched${target_suffix}
+    SRCS rcl/test_count_matched.cpp
+    INCLUDE_DIRS ${osrf_testing_tools_cpp_INCLUDE_DIRS}
+    ENV ${rmw_implementation_env_var}
+    APPEND_LIBRARY_DIRS ${extra_lib_dirs}
+    LIBRARIES ${PROJECT_NAME}
+    AMENT_DEPENDENCIES ${rmw_implementation} "test_msgs"
+  )
+
   rcl_add_custom_gtest(test_rcl${target_suffix}
     SRCS rcl/test_rcl.cpp
     ENV ${rmw_implementation_env_var} ${memory_tools_ld_preload_env_var}

rcl/test/rcl/test_count_matched.cpp

@@ -0,0 +1,171 @@
+// Copyright 2018 Open Source Robotics Foundation, Inc.
+//
+// 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 <gtest/gtest.h>
+
+#include <chrono>
+#include <string>
+#include <thread>
+
+#include "rcl/rcl.h"
+#include "rcl/publisher.h"
+#include "rcl/subscription.h"
+
+#include "rcutils/logging_macros.h"
+
+#include "test_msgs/msg/primitives.h"
+#include "test_msgs/srv/primitives.h"
+
+#include "rcl/error_handling.h"
+
+#ifdef RMW_IMPLEMENTATION
+# define CLASSNAME_(NAME, SUFFIX) NAME ## __ ## SUFFIX
+# define CLASSNAME(NAME, SUFFIX) CLASSNAME_(NAME, SUFFIX)
+#else
+# define CLASSNAME(NAME, SUFFIX) NAME
+#endif
+
+class CLASSNAME (TestCountFixture, RMW_IMPLEMENTATION) : public ::testing::Test
+{
+public:
+  rcl_node_t * node_ptr;
+  rcl_wait_set_t * wait_set_ptr;
+  void SetUp()
+  {
+    rcl_ret_t ret;
+    rcl_node_options_t node_options = rcl_node_get_default_options();
+
+    ret = rcl_init(0, nullptr, rcl_get_default_allocator());
+    ASSERT_EQ(RCL_RET_OK, ret) << rcl_get_error_string().str;
+    this->node_ptr = new rcl_node_t;
+    *this->node_ptr = rcl_get_zero_initialized_node();
+    const char * name = "test_count_node";
+    ret = rcl_node_init(this->node_ptr, name, "", &node_options);
+    ASSERT_EQ(RCL_RET_OK, ret) << rcl_get_error_string().str;
+  }
+
+  void TearDown()
+  {
+    rcl_ret_t ret;
+    ret = rcl_node_fini(this->node_ptr);
+    delete this->node_ptr;
+    EXPECT_EQ(RCL_RET_OK, ret) << rcl_get_error_string().str;
+
+    ret = rcl_shutdown();
+    EXPECT_EQ(RCL_RET_OK, ret) << rcl_get_error_string().str;
+  }
+};
+
+TEST_F(CLASSNAME(TestCountFixture, RMW_IMPLEMENTATION), test_count_matched_functions) {
+  std::string topic_name("/test_count_matched_functions__");
+  rcl_ret_t ret;
+
+  rcl_publisher_t pub = rcl_get_zero_initialized_publisher();
+  rcl_publisher_options_t pub_ops = rcl_publisher_get_default_options();
+  auto ts = ROSIDL_GET_MSG_TYPE_SUPPORT(test_msgs, msg, Primitives);
+  ret = rcl_publisher_init(&pub, this->node_ptr, ts, topic_name.c_str(), &pub_ops);
+  EXPECT_EQ(RCL_RET_OK, ret) << rcl_get_error_string().str;
+  rcl_reset_error();
+
+  {
+    size_t subscription_count;
+    ret = rcl_publisher_get_subscription_count(&pub, &subscription_count);
+    EXPECT_EQ(RCL_RET_OK, ret) << rcl_get_error_string().str;
+    rcl_reset_error();
+    EXPECT_EQ(0u, subscription_count);
+  }
+
+  rcl_subscription_t sub = rcl_get_zero_initialized_subscription();
+  rcl_subscription_options_t sub_ops = rcl_subscription_get_default_options();
+  ret = rcl_subscription_init(&sub, this->node_ptr, ts, topic_name.c_str(), &sub_ops);
+  EXPECT_EQ(RCL_RET_OK, ret) << rcl_get_error_string().str;
+  rcl_reset_error();
+
+  // This sleep is currently needed to allow opensplice and connext to correctly fire
+  // the on_publication_matched/on_subscription_matched functions.
+  std::this_thread::sleep_for(std::chrono::milliseconds(10));
+
+  {
+    size_t subscription_count;
+    ret = rcl_publisher_get_subscription_count(&pub, &subscription_count);
+    EXPECT_EQ(RCL_RET_OK, ret) << rcl_get_error_string().str;
+    rcl_reset_error();
+    EXPECT_EQ(1u, subscription_count);
+  }
+
+  {
+    size_t publisher_count;
+    ret = rcl_subscription_get_publisher_count(&sub, &publisher_count);
+    EXPECT_EQ(RCL_RET_OK, ret) << rcl_get_error_string().str;
+    rcl_reset_error();
+    EXPECT_EQ(1u, publisher_count);
+  }
+
+  rcl_subscription_t sub2 = rcl_get_zero_initialized_subscription();
+  rcl_subscription_options_t sub2_ops = rcl_subscription_get_default_options();
+  ret = rcl_subscription_init(&sub2, this->node_ptr, ts, topic_name.c_str(), &sub2_ops);
+  EXPECT_EQ(RCL_RET_OK, ret) << rcl_get_error_string().str;
+  rcl_reset_error();
+
+  // This sleep is currently needed to allow opensplice and connext to correctly fire
+  // the on_publication_matched/on_subscription_matched functions.
+  std::this_thread::sleep_for(std::chrono::milliseconds(10));
+
+  {
+    size_t subscription_count;
+    ret = rcl_publisher_get_subscription_count(&pub, &subscription_count);
+    EXPECT_EQ(RCL_RET_OK, ret) << rcl_get_error_string().str;
+    rcl_reset_error();
+    EXPECT_EQ(2u, subscription_count);
+  }
+
+  {
+    size_t publisher_count;
+    ret = rcl_subscription_get_publisher_count(&sub, &publisher_count);
+    EXPECT_EQ(RCL_RET_OK, ret) << rcl_get_error_string().str;
+    rcl_reset_error();
+    EXPECT_EQ(1u, publisher_count);
+  }
+
+  {
+    size_t publisher_count;
+    ret = rcl_subscription_get_publisher_count(&sub2, &publisher_count);
+    EXPECT_EQ(RCL_RET_OK, ret) << rcl_get_error_string().str;
+    rcl_reset_error();
+    EXPECT_EQ(1u, publisher_count);
+  }
+
+  ret = rcl_publisher_fini(&pub, this->node_ptr);
+  EXPECT_EQ(RCL_RET_OK, ret) << rcl_get_error_string().str;
+  rcl_reset_error();
+
+  // This sleep is currently needed to allow opensplice and connext to correctly fire
+  // the on_publication_matched/on_subscription_matched functions.
+  std::this_thread::sleep_for(std::chrono::milliseconds(10));
+
+  {
+    size_t publisher_count;
+    ret = rcl_subscription_get_publisher_count(&sub, &publisher_count);
+    EXPECT_EQ(RCL_RET_OK, ret) << rcl_get_error_string().str;
+    rcl_reset_error();
+    EXPECT_EQ(0u, publisher_count);
+  }
+
+  {
+    size_t publisher_count;
+    ret = rcl_subscription_get_publisher_count(&sub2, &publisher_count);
+    EXPECT_EQ(RCL_RET_OK, ret) << rcl_get_error_string().str;
+    rcl_reset_error();
+    EXPECT_EQ(0u, publisher_count);
+  }
+}