Fix dangerous std::bind capture in ParameterEventHandler implementation

rclcpp/include/rclcpp/parameter_event_handler.hpp

@@ -173,9 +173,13 @@ class ParameterEventHandler
   {
     auto node_topics = rclcpp::node_interfaces::get_node_topics_interface(node);
 
+    callbacks_ = std::make_shared<Callbacks>();
+
     event_subscription_ = rclcpp::create_subscription<rcl_interfaces::msg::ParameterEvent>(
       node_topics, "/parameter_events", qos,
-      std::bind(&ParameterEventHandler::event_callback, this, std::placeholders::_1));
+      [callbacks = callbacks_](const rcl_interfaces::msg::ParameterEvent & event) {
+        callbacks->event_callback(event);
+      });
   }
 
   using ParameterEventCallbackType =
@@ -285,17 +289,6 @@ class ParameterEventHandler
   using CallbacksContainerType = std::list<ParameterCallbackHandle::WeakPtr>;
 
 protected:
-  /// Callback for parameter events subscriptions.
-  RCLCPP_PUBLIC
-  void
-  event_callback(const rcl_interfaces::msg::ParameterEvent & event);
-
-  // Utility function for resolving node path.
-  std::string resolve_path(const std::string & path);
-
-  // Node interface used for base functionality
-  std::shared_ptr<rclcpp::node_interfaces::NodeBaseInterface> node_base_;
-
   // *INDENT-OFF* Uncrustify doesn't handle indented public/private labels
   // Hash function for string pair required in std::unordered_map
   // See: https://stackoverflow.com/questions/35985960/c-why-is-boosthash-combine-the-best-way-to-combine-hash-values
@@ -319,18 +312,34 @@ class ParameterEventHandler
   };
   // *INDENT-ON*
 
-  // Map container for registered parameters
-  std::unordered_map<
-    std::pair<std::string, std::string>,
-    CallbacksContainerType,
-    StringPairHash
-  > parameter_callbacks_;
+  struct Callbacks
+  {
+    std::recursive_mutex mutex_;
+
+    // Map container for registered parameters
+    std::unordered_map<
+      std::pair<std::string, std::string>,
+      CallbacksContainerType,
+      StringPairHash
+    > parameter_callbacks_;
 
-  rclcpp::Subscription<rcl_interfaces::msg::ParameterEvent>::SharedPtr event_subscription_;
+    std::list<ParameterEventCallbackHandle::WeakPtr> event_callbacks_;
+
+    /// Callback for parameter events subscriptions.
+    RCLCPP_PUBLIC
+    void
+    event_callback(const rcl_interfaces::msg::ParameterEvent & event);
+  };
 
-  std::list<ParameterEventCallbackHandle::WeakPtr> event_callbacks_;
+  std::shared_ptr<Callbacks> callbacks_;
 
-  std::recursive_mutex mutex_;
+  // Utility function for resolving node path.
+  std::string resolve_path(const std::string & path);
+
+  // Node interface used for base functionality
+  std::shared_ptr<rclcpp::node_interfaces::NodeBaseInterface> node_base_;
+
+  rclcpp::Subscription<rcl_interfaces::msg::ParameterEvent>::SharedPtr event_subscription_;
 };
 
 }  // namespace rclcpp

rclcpp/src/rclcpp/parameter_event_handler.cpp

@@ -29,10 +29,10 @@ ParameterEventCallbackHandle::SharedPtr
 ParameterEventHandler::add_parameter_event_callback(
   ParameterEventCallbackType callback)
 {
-  std::lock_guard<std::recursive_mutex> lock(mutex_);
+  std::lock_guard<std::recursive_mutex> lock(callbacks_->mutex_);
   auto handle = std::make_shared<ParameterEventCallbackHandle>();
   handle->callback = callback;
-  event_callbacks_.emplace_front(handle);
+  callbacks_->event_callbacks_.emplace_front(handle);
 
   return handle;
 }
@@ -41,15 +41,15 @@ void
 ParameterEventHandler::remove_parameter_event_callback(
   ParameterEventCallbackHandle::SharedPtr callback_handle)
 {
-  std::lock_guard<std::recursive_mutex> lock(mutex_);
+  std::lock_guard<std::recursive_mutex> lock(callbacks_->mutex_);
   auto it = std::find_if(
-    event_callbacks_.begin(),
-    event_callbacks_.end(),
+    callbacks_->event_callbacks_.begin(),
+    callbacks_->event_callbacks_.end(),
     [callback_handle](const auto & weak_handle) {
       return callback_handle.get() == weak_handle.lock().get();
     });
-  if (it != event_callbacks_.end()) {
-    event_callbacks_.erase(it);
+  if (it != callbacks_->event_callbacks_.end()) {
+    callbacks_->event_callbacks_.erase(it);
   } else {
     throw std::runtime_error("Callback doesn't exist");
   }
@@ -61,15 +61,15 @@ ParameterEventHandler::add_parameter_callback(
   ParameterCallbackType callback,
   const std::string & node_name)
 {
-  std::lock_guard<std::recursive_mutex> lock(mutex_);
+  std::lock_guard<std::recursive_mutex> lock(callbacks_->mutex_);
   auto full_node_name = resolve_path(node_name);
 
   auto handle = std::make_shared<ParameterCallbackHandle>();
   handle->callback = callback;
   handle->parameter_name = parameter_name;
   handle->node_name = full_node_name;
   // the last callback registered is executed first.
-  parameter_callbacks_[{parameter_name, full_node_name}].emplace_front(handle);
+  callbacks_->parameter_callbacks_[{parameter_name, full_node_name}].emplace_front(handle);
 
   return handle;
 }
@@ -78,9 +78,9 @@ void
 ParameterEventHandler::remove_parameter_callback(
   ParameterCallbackHandle::SharedPtr callback_handle)
 {
-  std::lock_guard<std::recursive_mutex> lock(mutex_);
+  std::lock_guard<std::recursive_mutex> lock(callbacks_->mutex_);
   auto handle = callback_handle.get();
-  auto & container = parameter_callbacks_[{handle->parameter_name, handle->node_name}];
+  auto & container = callbacks_->parameter_callbacks_[{handle->parameter_name, handle->node_name}];
   auto it = std::find_if(
     container.begin(),
     container.end(),
@@ -90,7 +90,7 @@ ParameterEventHandler::remove_parameter_callback(
   if (it != container.end()) {
     container.erase(it);
     if (container.empty()) {
-      parameter_callbacks_.erase({handle->parameter_name, handle->node_name});
+      callbacks_->parameter_callbacks_.erase({handle->parameter_name, handle->node_name});
     }
   } else {
     throw std::runtime_error("Callback doesn't exist");
@@ -158,7 +158,7 @@ ParameterEventHandler::get_parameters_from_event(
 }
 
 void
-ParameterEventHandler::event_callback(const rcl_interfaces::msg::ParameterEvent & event)
+ParameterEventHandler::Callbacks::event_callback(const rcl_interfaces::msg::ParameterEvent & event)
 {
   std::lock_guard<std::recursive_mutex> lock(mutex_);
 

rclcpp/test/rclcpp/test_parameter_event_handler.cpp

@@ -29,17 +29,17 @@ class TestParameterEventHandler : public rclcpp::ParameterEventHandler
 
   void test_event(rcl_interfaces::msg::ParameterEvent::ConstSharedPtr event)
   {
-    event_callback(*event);
+    callbacks_->event_callback(*event);
   }
 
   size_t num_event_callbacks()
   {
-    return event_callbacks_.size();
+    return callbacks_->event_callbacks_.size();
   }
 
   size_t num_parameter_callbacks()
   {
-    return parameter_callbacks_.size();
+    return callbacks_->parameter_callbacks_.size();
   }
 };