add method for accessing rmw_context from rcl_context (#372)

Signed-off-by: William Woodall <william@osrfoundation.org>

rcl/include/rcl/context.h

@@ -261,6 +261,28 @@ RCL_WARN_UNUSED
 bool
 rcl_context_is_valid(rcl_context_t * context);
 
+/// Return pointer to the rmw context if the given context is currently valid, otherwise `NULL`.
+/**
+ * If context is `NULL`, then `NULL` is returned.
+ * If context is zero-initialized, then `NULL` is returned.
+ * If context is uninitialized, then it is undefined behavior.
+ *
+ * Attribute          | Adherence
+ * ------------------ | -------------
+ * Allocates Memory   | No
+ * Thread-Safe        | Yes
+ * Uses Atomics       | Yes
+ * Lock-Free          | Yes [1]
+ * <i>[1] if `atomic_is_lock_free()` returns true for `atomic_uint_least64_t`</i>
+ *
+ * \param[in] context object from which the rmw context should be retrieved.
+ * \return pointer to rmw context if valid, otherwise `NULL`
+ */
+RCL_PUBLIC
+RCL_WARN_UNUSED
+rmw_context_t *
+rcl_context_get_rmw_context(rcl_context_t * context);
+
 #ifdef __cplusplus
 }
 #endif

rcl/src/rcl/context.c

@@ -84,6 +84,14 @@ rcl_context_is_valid(rcl_context_t * context)
   return 0 != rcl_context_get_instance_id(context);
 }
 
+rmw_context_t *
+rcl_context_get_rmw_context(rcl_context_t * context)
+{
+  RCL_CHECK_ARGUMENT_FOR_NULL(context, NULL);
+  RCL_CHECK_FOR_NULL_WITH_MSG(context->impl, "context is zero-initialized", return NULL);
+  return &(context->impl->rmw_context);
+}
+
 void
 __cleanup_context(rcl_context_t * context)
 {

rcl/test/CMakeLists.txt

@@ -59,6 +59,14 @@ function(test_target_function)
     AMENT_DEPENDENCIES ${rmw_implementation}
   )
 
+  rcl_add_custom_gtest(test_context${target_suffix}
+    SRCS rcl/test_context.cpp
+    ENV ${rmw_implementation_env_var} ${memory_tools_ld_preload_env_var}
+    APPEND_LIBRARY_DIRS ${extra_lib_dirs}
+    LIBRARIES ${PROJECT_NAME} osrf_testing_tools_cpp::memory_tools
+    AMENT_DEPENDENCIES ${rmw_implementation}
+  )
+
   rcl_add_custom_gtest(test_get_node_names${target_suffix}
     SRCS rcl/test_get_node_names.cpp
     INCLUDE_DIRS ${osrf_testing_tools_cpp_INCLUDE_DIRS}

rcl/test/rcl/test_context.cpp

@@ -0,0 +1,114 @@
+// Copyright 2019 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 "osrf_testing_tools_cpp/memory_tools/gtest_quickstart.hpp"
+#include "osrf_testing_tools_cpp/scope_exit.hpp"
+#include "rcl/context.h"
+#include "rcl/error_handling.h"
+#include "rcl/init.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 (TestContextFixture, RMW_IMPLEMENTATION) : public ::testing::Test {};
+
+// Test the rcl_context_t's normal function.
+// Note: that init/fini are tested in test_init.cpp.
+TEST_F(CLASSNAME(TestContextFixture, RMW_IMPLEMENTATION), nominal) {
+  osrf_testing_tools_cpp::memory_tools::ScopedQuickstartGtest scoped_quickstart_gtest;
+
+  // This prevents memory allocations when setting error states in the future.
+  rcl_ret_t ret = rcl_initialize_error_handling_thread_local_storage(rcl_get_default_allocator());
+  ASSERT_EQ(ret, RCL_RET_OK);
+
+  // initialization with rcl_init
+  rcl_context_t context = rcl_get_zero_initialized_context();
+  rcl_init_options_t init_options = rcl_get_zero_initialized_init_options();
+  ret = rcl_init_options_init(&init_options, rcl_get_default_allocator());
+  ASSERT_EQ(ret, RCL_RET_OK);
+  ret = rcl_init(0, nullptr, &init_options, &context);
+  ASSERT_EQ(ret, RCL_RET_OK);
+  OSRF_TESTING_TOOLS_CPP_SCOPE_EXIT({
+    ret = rcl_shutdown(&context);
+    EXPECT_EQ(ret, RCL_RET_OK);
+    ret = rcl_context_fini(&context);
+    EXPECT_EQ(ret, RCL_RET_OK);
+  });
+
+  // test rcl_context_get_init_options
+  const rcl_init_options_t * init_options_ptr;
+  EXPECT_NO_MEMORY_OPERATIONS({
+    init_options_ptr = rcl_context_get_init_options(nullptr);
+  });
+  EXPECT_EQ(init_options_ptr, nullptr);
+  EXPECT_TRUE(rcl_error_is_set());
+  rcl_reset_error();
+
+  EXPECT_NO_MEMORY_OPERATIONS({
+    init_options_ptr = rcl_context_get_init_options(&context);
+  });
+  EXPECT_NE(init_options_ptr, nullptr) << rcl_get_error_string().str;
+  rcl_reset_error();
+
+  // test rcl_context_get_instance_id
+  rcl_context_instance_id_t instance_id;
+  EXPECT_NO_MEMORY_OPERATIONS({
+    instance_id = rcl_context_get_instance_id(nullptr);
+  });
+  EXPECT_EQ(instance_id, 0UL);
+  EXPECT_TRUE(rcl_error_is_set());
+  rcl_reset_error();
+
+  EXPECT_NO_MEMORY_OPERATIONS({
+    instance_id = rcl_context_get_instance_id(&context);
+  });
+  EXPECT_NE(instance_id, 0UL) << rcl_get_error_string().str;
+  rcl_reset_error();
+
+  // test rcl_context_is_valid
+  bool is_valid;
+  EXPECT_NO_MEMORY_OPERATIONS({
+    is_valid = rcl_context_is_valid(nullptr);
+  });
+  EXPECT_FALSE(is_valid);
+  EXPECT_TRUE(rcl_error_is_set());
+  rcl_reset_error();
+
+  EXPECT_NO_MEMORY_OPERATIONS({
+    is_valid = rcl_context_is_valid(&context);
+  });
+  EXPECT_TRUE(is_valid) << rcl_get_error_string().str;
+  rcl_reset_error();
+
+  // test rcl_context_get_rmw_context
+  rmw_context_t * rmw_context_ptr;
+  EXPECT_NO_MEMORY_OPERATIONS({
+    rmw_context_ptr = rcl_context_get_rmw_context(nullptr);
+  });
+  EXPECT_EQ(rmw_context_ptr, nullptr);
+  EXPECT_TRUE(rcl_error_is_set());
+  rcl_reset_error();
+
+  EXPECT_NO_MEMORY_OPERATIONS({
+    rmw_context_ptr = rcl_context_get_rmw_context(&context);
+  });
+  EXPECT_NE(rmw_context_ptr, nullptr) << rcl_get_error_string().str;
+  rcl_reset_error();
+}