add rcl_init_time_source (#113)

* add rcl_init_time_source / rcl_fini_time_source

* docs

rcl/include/rcl/time.h

@@ -102,6 +102,41 @@ RCL_WARN_UNUSED
 bool
 rcl_time_source_valid(rcl_time_source_t * time_source);
 
+/// Initialize a time_source based on the passed type.
+/**
+ * This will allocate all necessary internal structures, and initialize variables.
+ *
+ * \param[in] time_source_type the type identifying the time source to provide
+ * \param[in] time_source the handle to the time_source which is being initialized
+ * \return `RCL_RET_OK` if the time source was successfully initialized, or
+ * \return `RCL_RET_INVALID_ARGUMENT` if any arguments are invalid, or
+ * \return `RCL_RET_ERROR` an unspecified error occur.
+ */
+RCL_PUBLIC
+RCL_WARN_UNUSED
+rcl_ret_t
+rcl_init_time_source(
+  enum rcl_time_source_type_t time_source_type, rcl_time_source_t * time_source
+);
+
+/// Finalize a time_source.
+/**
+ * This will deallocate all necessary internal structures, and clean up any variables.
+ * It can be combined with any of the init functions.
+ *
+ * Passing a time_source with type RCL_TIME_SOURCE_UNINITIALIZED will result in
+ * RCL_RET_INVALID_ARGUMENT being returned.
+ *
+ * \param[in] time_source the handle to the time_source which is being finalized
+ * \return `RCL_RET_OK` if the time source was successfully finalized, or
+ * \return `RCL_RET_INVALID_ARGUMENT` if any arguments are invalid, or
+ * \return `RCL_RET_ERROR` an unspecified error occur.
+ */
+RCL_PUBLIC
+RCL_WARN_UNUSED
+rcl_ret_t
+rcl_fini_time_source(rcl_time_source_t * time_source);
+
 /// Initialize a time_source as a RCL_ROS_TIME time source.
 /**
  * This will allocate all necessary internal structures, and initialize variables.

rcl/src/rcl/time.c

@@ -88,6 +88,45 @@ rcl_time_source_valid(rcl_time_source_t * time_source)
   return true;
 }
 
+rcl_ret_t
+rcl_init_time_source(
+  enum rcl_time_source_type_t time_source_type, rcl_time_source_t * time_source
+)
+{
+  RCL_CHECK_ARGUMENT_FOR_NULL(time_source, RCL_RET_INVALID_ARGUMENT);
+  switch (time_source_type) {
+    case RCL_TIME_SOURCE_UNINITIALIZED:
+      rcl_init_generic_time_source(time_source);
+      return RCL_RET_OK;
+    case RCL_ROS_TIME:
+      return rcl_init_ros_time_source(time_source);
+    case RCL_SYSTEM_TIME:
+      return rcl_init_system_time_source(time_source);
+    case RCL_STEADY_TIME:
+      return rcl_init_steady_time_source(time_source);
+    default:
+      return RCL_RET_INVALID_ARGUMENT;
+  }
+}
+
+rcl_ret_t
+rcl_fini_time_source(rcl_time_source_t * time_source)
+{
+  RCL_CHECK_ARGUMENT_FOR_NULL(time_source, RCL_RET_INVALID_ARGUMENT);
+  switch (time_source->type) {
+    case RCL_ROS_TIME:
+      return rcl_fini_ros_time_source(time_source);
+    case RCL_SYSTEM_TIME:
+      return rcl_fini_system_time_source(time_source);
+    case RCL_STEADY_TIME:
+      return rcl_fini_steady_time_source(time_source);
+    case RCL_TIME_SOURCE_UNINITIALIZED:
+    // fall through
+    default:
+      return RCL_RET_INVALID_ARGUMENT;
+  }
+}
+
 rcl_ret_t
 rcl_init_ros_time_source(rcl_time_source_t * time_source)
 {

rcl/test/rcl/test_time.cpp

@@ -291,6 +291,44 @@ TEST(CLASSNAME(rcl_time, RMW_IMPLEMENTATION), default_time_source_instanciation)
   ASSERT_TRUE(rcl_time_source_valid(system_time_source));
 }
 
+TEST(CLASSNAME(rcl_time, RMW_IMPLEMENTATION), specific_time_source_instantiation) {
+  {
+    rcl_time_source_t uninitialized_time_source;
+    rcl_ret_t ret = rcl_init_time_source(
+      RCL_TIME_SOURCE_UNINITIALIZED, &uninitialized_time_source);
+    EXPECT_EQ(ret, RCL_RET_OK) << rcl_get_error_string_safe();
+    EXPECT_EQ(uninitialized_time_source.type, RCL_TIME_SOURCE_UNINITIALIZED) <<
+      "Expected time source of type RCL_TIME_SOURCE_UNINITIALIZED";
+  }
+  {
+    rcl_time_source_t ros_time_source;
+    rcl_ret_t ret = rcl_init_time_source(RCL_ROS_TIME, &ros_time_source);
+    EXPECT_EQ(ret, RCL_RET_OK) << rcl_get_error_string_safe();
+    EXPECT_EQ(ros_time_source.type, RCL_ROS_TIME) <<
+      "Expected time source of type RCL_ROS_TIME";
+    ret = rcl_fini_time_source(&ros_time_source);
+    EXPECT_EQ(ret, RCL_RET_OK) << rcl_get_error_string_safe();
+  }
+  {
+    rcl_time_source_t system_time_source;
+    rcl_ret_t ret = rcl_init_time_source(RCL_SYSTEM_TIME, &system_time_source);
+    EXPECT_EQ(ret, RCL_RET_OK) << rcl_get_error_string_safe();
+    EXPECT_EQ(system_time_source.type, RCL_SYSTEM_TIME) <<
+      "Expected time source of type RCL_SYSTEM_TIME";
+    ret = rcl_fini_time_source(&system_time_source);
+    EXPECT_EQ(ret, RCL_RET_OK) << rcl_get_error_string_safe();
+  }
+  {
+    rcl_time_source_t steady_time_source;
+    rcl_ret_t ret = rcl_init_time_source(RCL_STEADY_TIME, &steady_time_source);
+    EXPECT_EQ(ret, RCL_RET_OK) << rcl_get_error_string_safe();
+    EXPECT_EQ(steady_time_source.type, RCL_STEADY_TIME) <<
+      "Expected time source of type RCL_STEADY_TIME";
+    ret = rcl_fini_time_source(&steady_time_source);
+    EXPECT_EQ(ret, RCL_RET_OK) << rcl_get_error_string_safe();
+  }
+}
+
 TEST(CLASSNAME(rcl_time, RMW_IMPLEMENTATION), rcl_time_difference) {
   rcl_ret_t ret;
   rcl_time_point_t a, b;