Multiple calls to Context::shutdown will throw an exception

Signed-off-by: Barry Xu <[email protected]>

rclpy/src/rclpy/context.cpp

@@ -151,13 +151,17 @@ void
 Context::shutdown()
 {
   std::lock_guard<std::mutex> guard{g_contexts_mutex};
+  if (already_shutdown_) {
+    throw CONTEXT_ALREADY_SHUTDOWN("Context already shutdown.");
+  }
   auto iter = std::find(g_contexts.begin(), g_contexts.end(), rcl_context_.get());
   if (iter != g_contexts.end()) {
     g_contexts.erase(iter);
     rcl_ret_t ret = rcl_shutdown(rcl_context_.get());
     if (RCL_RET_OK != ret) {
       throw RCLError("failed to shutdown");
     }
+    already_shutdown_ = true;
   }
 }
 

rclpy/src/rclpy/context.hpp

@@ -101,6 +101,7 @@ class Context : public Destroyable, public std::enable_shared_from_this<Context>
 
 private:
   std::shared_ptr<rcl_context_t> rcl_context_;
+  bool already_shutdown_{false};
 };
 
 /// Define a pybind11 wrapper for an rclpy::Context

rclpy/src/rclpy/exceptions.hpp

@@ -80,6 +80,11 @@ class InvalidHandle : public std::runtime_error
   using std::runtime_error::runtime_error;
 };
 
+class CONTEXT_ALREADY_SHUTDOWN : public std::runtime_error
+{
+  using std::runtime_error::runtime_error;
+};
+
 }  // namespace rclpy
 
 #endif  // RCLPY__EXCEPTIONS_HPP_

rclpy/test/test_init_shutdown.py

@@ -74,6 +74,15 @@ def test_double_init():
         rclpy.shutdown(context=context)
 
 
+def test_double_shutdown():
+    context = rclpy.context.Context()
+    rclpy.init(context=context)
+    assert context.ok()
+    rclpy.shutdown(context=context)
+    with pytest.raises(RuntimeError):
+        rclpy.shutdown(context=context)
+
+
 def test_create_node_without_init():
     context = rclpy.context.Context()
     with pytest.raises(NotInitializedException):