[foxy backport] Derive and throw exception in spin_some spin_all for StaticSingleThreadedExecutor (#1385)

* Derive and throw exception in spin_some spin_all for StaticSingleThreadedExecutor (#1220)

* Derive and throw exception in spin_some spin_all

Signed-off-by: Stephen Brawner <brawner@gmail.com>

* Fix style and add unit test

Signed-off-by: Stephen Brawner <brawner@gmail.com>

* Remove header changes and throw exceptions in .cpp

Signed-off-by: Stephen Brawner <brawner@gmail.com>

rclcpp/include/rclcpp/exceptions/exceptions.hpp

@@ -100,6 +100,15 @@ public:
   {}
 };
 
+class UnimplementedError : public std::runtime_error
+{
+public:
+  UnimplementedError()
+  : std::runtime_error("This code is unimplemented.") {}
+  explicit UnimplementedError(const std::string & msg)
+  : std::runtime_error(msg) {}
+};
+
 /// Throw a C++ std::exception which was created based on an rcl error.
 /**
  * Passing nullptr for reset_error is safe and will avoid calling any function

rclcpp/src/rclcpp/executor.cpp

@@ -22,6 +22,7 @@
 
 #include "rclcpp/exceptions.hpp"
 #include "rclcpp/executor.hpp"
+#include "rclcpp/executors/static_single_threaded_executor.hpp"
 #include "rclcpp/node.hpp"
 #include "rclcpp/scope_exit.hpp"
 #include "rclcpp/utilities.hpp"
@@ -215,6 +216,12 @@ Executor::spin_node_some(std::shared_ptr<rclcpp::Node> node)
 void
 Executor::spin_some(std::chrono::nanoseconds max_duration)
 {
+  if (nullptr != dynamic_cast<executors::StaticSingleThreadedExecutor *>(this)) {
+    throw rclcpp::exceptions::UnimplementedError(
+            "spin_some is not implemented for StaticSingleThreadedExecutor, use spin or "
+            "spin_until_future_complete");
+  }
+
   auto start = std::chrono::steady_clock::now();
   auto max_duration_not_elapsed = [max_duration, start]() {
       if (std::chrono::nanoseconds(0) == max_duration) {
@@ -256,6 +263,11 @@ Executor::spin_once_impl(std::chrono::nanoseconds timeout)
 void
 Executor::spin_once(std::chrono::nanoseconds timeout)
 {
+  if (nullptr != dynamic_cast<executors::StaticSingleThreadedExecutor *>(this)) {
+    throw rclcpp::exceptions::UnimplementedError(
+            "spin_once is not implemented for StaticSingleThreadedExecutor, use spin or "
+            "spin_until_future_complete");
+  }
   if (spinning.exchange(true)) {
     throw std::runtime_error("spin_once() called while already spinning");
   }

rclcpp/test/CMakeLists.txt

@@ -458,6 +458,12 @@ if(TARGET test_interface_traits)
   target_link_libraries(test_interface_traits ${PROJECT_NAME})
 endif()
 
+ament_add_gtest(test_static_single_threaded_executor rclcpp/executors/test_static_single_threaded_executor.cpp
+  APPEND_LIBRARY_DIRS "${append_library_dirs}")
+if(TARGET test_static_single_threaded_executor)
+  target_link_libraries(test_static_single_threaded_executor ${PROJECT_NAME})
+endif()
+
 ament_add_gtest(test_multi_threaded_executor rclcpp/executors/test_multi_threaded_executor.cpp
   APPEND_LIBRARY_DIRS "${append_library_dirs}")
 if(TARGET test_multi_threaded_executor)

rclcpp/test/rclcpp/executors/test_static_single_threaded_executor.cpp

@@ -0,0 +1,48 @@
+// Copyright 2020 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 <memory>
+
+#include "rclcpp/exceptions.hpp"
+#include "rclcpp/node.hpp"
+#include "rclcpp/rclcpp.hpp"
+#include "rclcpp/executors.hpp"
+
+using namespace std::chrono_literals;
+
+class TestStaticSingleThreadedExecutor : public ::testing::Test
+{
+public:
+  void SetUp()
+  {
+    rclcpp::init(0, nullptr);
+  }
+
+  void TearDown()
+  {
+    rclcpp::shutdown();
+  }
+};
+
+TEST_F(TestStaticSingleThreadedExecutor, check_unimplemented) {
+  rclcpp::executors::StaticSingleThreadedExecutor executor;
+  auto node = std::make_shared<rclcpp::Node>("node", "ns");
+  executor.add_node(node);
+
+  EXPECT_THROW(executor.spin_some(), rclcpp::exceptions::UnimplementedError);
+  EXPECT_THROW(executor.spin_once(0ns), rclcpp::exceptions::UnimplementedError);
+}