rclc_executor: improve enum type names (#379)

(cherry picked from commit 14c2c41)

Author: JanStaschulat

rclc/include/rclc/executor.h

@@ -40,22 +40,33 @@ extern "C"
     processed in a user-defined order.
 */
 
-/* defines the semantics of data communication
-   RCLCPP_EXECUTOR - same semantics as in the rclcpp Executor ROS2(Eloquent)
-   LET             - logical execution time
+/** Defines the semantics when data is taken from DDS
+ *  SEMANTICS_RCLCPP_EXECUTOR        - same semantics as in rclcpp Executor. Data of a subscription
+ *                                     is taken from DDS just before the corresponding callback
+ *                                     is called by the Executor.
+ *  SEMANTICS_LOGICAL_EXECUTION_TIME - logical execution time semantics. At one sampling point t
+ *                                     new data of all ready subscriptions are taken from DDS.
+ *                                     During (sequential) processing of these callbacks the
+ *                                     data is used as per sampling point t. If new data arrived
+ *                                     between the sampling point t and the time point at which
+ *                                     the callback is called, it would not be considered in this
+ *                                     `rclc_executor_spin_some` iteration.
 */
 typedef enum
 {
-  RCLCPP_EXECUTOR,
-  LET
+  RCLC_SEMANTICS_RCLCPP_EXECUTOR,
+  RCLC_SEMANTICS_LOGICAL_EXECUTION_TIME
 } rclc_executor_semantics_t;
 
+/**
+ * Different types of Executors.
+*/
 typedef enum
 {
-  NONE,
-  SINGLE_THREADED,
-  MULTI_THREADED,
-  NON_POSIX,
+  RCLC_EXECUTOR_NOT_INITIALIZED,
+  RCLC_EXECUTOR_SINGLE_THREADED,
+  RCLC_EXECUTOR_MULTI_THREADED,
+  RCLC_EXECUTOR_NON_POSIX,
 } rclc_executor_type_t;
 
 /// Type definition for trigger function. With the parameters:

rclc/src/rclc/executor.c

@@ -141,7 +141,7 @@ rclc_executor_init(
   rclc_executor_set_trigger(executor, rclc_executor_trigger_any, NULL);
 
   // default semantics
-  rclc_executor_set_semantics(executor, RCLCPP_EXECUTOR);
+  rclc_executor_set_semantics(executor, RCLC_SEMANTICS_RCLCPP_EXECUTOR);
 
   return ret;
 }
@@ -1956,10 +1956,10 @@ rclc_executor_spin_some(rclc_executor_t * executor, const uint64_t timeout_ns)
 
   // based on semantics process input data
   switch (executor->data_comm_semantics) {
-    case LET:
+    case RCLC_SEMANTICS_LOGICAL_EXECUTION_TIME:
       rc = _rclc_let_scheduling(executor);
       break;
-    case RCLCPP_EXECUTOR:
+    case RCLC_SEMANTICS_RCLCPP_EXECUTOR:
       rc = _rclc_default_scheduling(executor);
       break;
     default:

rclc/test/rclc/test_executor.cpp

@@ -1903,7 +1903,7 @@ TEST_F(TestDefaultExecutor, semantics_RCLCPP) {
   _pub_int_ptr = &this->pub1;
   _pub_int_msg_ptr = &this->pub1_msg;
   // ------------------------- test case setup ------------------------
-  rclc_executor_set_semantics(&executor, RCLCPP_EXECUTOR);
+  rclc_executor_set_semantics(&executor, RCLC_SEMANTICS_RCLCPP_EXECUTOR);
   this->pub1_msg.data = 1;
   _cb5_int_value = 0;  // received value in subscription2
   rc = rcl_publish(&this->pub1, &this->pub1_msg, nullptr);