ensure removal of guard conditions of expired nodes from memory strategy (#741)

* change memory strategy API from vector of nodes to list of nodes

Signed-off-by: Dirk Thomas <dirk-thomas@users.noreply.github.com>

* store guard_condition of node in executor and ensure that it is removed from the memory strategy

Signed-off-by: Dirk Thomas <dirk-thomas@users.noreply.github.com>

* add unit test

Signed-off-by: Dirk Thomas <dirk-thomas@users.noreply.github.com>

rclcpp/include/rclcpp/executor.hpp

@@ -364,7 +364,8 @@ protected:
 private:
   RCLCPP_DISABLE_COPY(Executor)
 
-  std::vector<rclcpp::node_interfaces::NodeBaseInterface::WeakPtr> weak_nodes_;
+  std::list<rclcpp::node_interfaces::NodeBaseInterface::WeakPtr> weak_nodes_;
+  std::list<const rcl_guard_condition_t *> guard_conditions_;
 };
 
 }  // namespace executor

rclcpp/include/rclcpp/memory_strategy.hpp

@@ -15,8 +15,8 @@
 #ifndef RCLCPP__MEMORY_STRATEGY_HPP_
 #define RCLCPP__MEMORY_STRATEGY_HPP_
 
+#include <list>
 #include <memory>
-#include <vector>
 
 #include "rcl/allocator.h"
 #include "rcl/wait.h"
@@ -42,11 +42,11 @@ class RCLCPP_PUBLIC MemoryStrategy
 {
 public:
   RCLCPP_SMART_PTR_DEFINITIONS_NOT_COPYABLE(MemoryStrategy)
-  using WeakNodeVector = std::vector<rclcpp::node_interfaces::NodeBaseInterface::WeakPtr>;
+  using WeakNodeList = std::list<rclcpp::node_interfaces::NodeBaseInterface::WeakPtr>;
 
   virtual ~MemoryStrategy() = default;
 
-  virtual bool collect_entities(const WeakNodeVector & weak_nodes) = 0;
+  virtual bool collect_entities(const WeakNodeList & weak_nodes) = 0;
 
   virtual size_t number_of_ready_subscriptions() const = 0;
   virtual size_t number_of_ready_services() const = 0;
@@ -67,22 +67,22 @@ public:
   virtual void
   get_next_subscription(
     rclcpp::executor::AnyExecutable & any_exec,
-    const WeakNodeVector & weak_nodes) = 0;
+    const WeakNodeList & weak_nodes) = 0;
 
   virtual void
   get_next_service(
     rclcpp::executor::AnyExecutable & any_exec,
-    const WeakNodeVector & weak_nodes) = 0;
+    const WeakNodeList & weak_nodes) = 0;
 
   virtual void
   get_next_client(
     rclcpp::executor::AnyExecutable & any_exec,
-    const WeakNodeVector & weak_nodes) = 0;
+    const WeakNodeList & weak_nodes) = 0;
 
   virtual void
   get_next_waitable(
     rclcpp::executor::AnyExecutable & any_exec,
-    const WeakNodeVector & weak_nodes) = 0;
+    const WeakNodeList & weak_nodes) = 0;
 
   virtual rcl_allocator_t
   get_allocator() = 0;
@@ -90,42 +90,42 @@ public:
   static rclcpp::SubscriptionBase::SharedPtr
   get_subscription_by_handle(
     std::shared_ptr<const rcl_subscription_t> subscriber_handle,
-    const WeakNodeVector & weak_nodes);
+    const WeakNodeList & weak_nodes);
 
   static rclcpp::ServiceBase::SharedPtr
   get_service_by_handle(
     std::shared_ptr<const rcl_service_t> service_handle,
-    const WeakNodeVector & weak_nodes);
+    const WeakNodeList & weak_nodes);
 
   static rclcpp::ClientBase::SharedPtr
   get_client_by_handle(
     std::shared_ptr<const rcl_client_t> client_handle,
-    const WeakNodeVector & weak_nodes);
+    const WeakNodeList & weak_nodes);
 
   static rclcpp::node_interfaces::NodeBaseInterface::SharedPtr
   get_node_by_group(
     rclcpp::callback_group::CallbackGroup::SharedPtr group,
-    const WeakNodeVector & weak_nodes);
+    const WeakNodeList & weak_nodes);
 
   static rclcpp::callback_group::CallbackGroup::SharedPtr
   get_group_by_subscription(
     rclcpp::SubscriptionBase::SharedPtr subscription,
-    const WeakNodeVector & weak_nodes);
+    const WeakNodeList & weak_nodes);
 
   static rclcpp::callback_group::CallbackGroup::SharedPtr
   get_group_by_service(
     rclcpp::ServiceBase::SharedPtr service,
-    const WeakNodeVector & weak_nodes);
+    const WeakNodeList & weak_nodes);
 
   static rclcpp::callback_group::CallbackGroup::SharedPtr
   get_group_by_client(
     rclcpp::ClientBase::SharedPtr client,
-    const WeakNodeVector & weak_nodes);
+    const WeakNodeList & weak_nodes);
 
   static rclcpp::callback_group::CallbackGroup::SharedPtr
   get_group_by_waitable(
     rclcpp::Waitable::SharedPtr waitable,
-    const WeakNodeVector & weak_nodes);
+    const WeakNodeList & weak_nodes);
 };
 
 }  // namespace memory_strategy

rclcpp/include/rclcpp/strategies/allocator_memory_strategy.hpp

@@ -150,7 +150,7 @@ public:
     );
   }
 
-  bool collect_entities(const WeakNodeVector & weak_nodes)
+  bool collect_entities(const WeakNodeList & weak_nodes)
   {
     bool has_invalid_weak_nodes = false;
     for (auto & weak_node : weak_nodes) {
@@ -265,7 +265,7 @@ public:
   virtual void
   get_next_subscription(
     executor::AnyExecutable & any_exec,
-    const WeakNodeVector & weak_nodes)
+    const WeakNodeList & weak_nodes)
   {
     auto it = subscription_handles_.begin();
     while (it != subscription_handles_.end()) {
@@ -309,7 +309,7 @@ public:
   virtual void
   get_next_service(
     executor::AnyExecutable & any_exec,
-    const WeakNodeVector & weak_nodes)
+    const WeakNodeList & weak_nodes)
   {
     auto it = service_handles_.begin();
     while (it != service_handles_.end()) {
@@ -342,7 +342,7 @@ public:
   }
 
   virtual void
-  get_next_client(executor::AnyExecutable & any_exec, const WeakNodeVector & weak_nodes)
+  get_next_client(executor::AnyExecutable & any_exec, const WeakNodeList & weak_nodes)
   {
     auto it = client_handles_.begin();
     while (it != client_handles_.end()) {
@@ -375,7 +375,7 @@ public:
   }
 
   virtual void
-  get_next_waitable(executor::AnyExecutable & any_exec, const WeakNodeVector & weak_nodes)
+  get_next_waitable(executor::AnyExecutable & any_exec, const WeakNodeList & weak_nodes)
   {
     auto it = waitable_handles_.begin();
     while (it != waitable_handles_.end()) {

rclcpp/src/rclcpp/executor.cpp

@@ -91,6 +91,10 @@ Executor::~Executor()
     }
   }
   weak_nodes_.clear();
+  for (auto & guard_condition : guard_conditions_) {
+    memory_strategy_->remove_guard_condition(guard_condition);
+  }
+  guard_conditions_.clear();
 
   // Finalize the wait set.
   if (rcl_wait_set_fini(&wait_set_) != RCL_RET_OK) {
@@ -128,6 +132,7 @@ Executor::add_node(rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_pt
     }
   }
   weak_nodes_.push_back(node_ptr);
+  guard_conditions_.push_back(node_ptr->get_notify_guard_condition());
   if (notify) {
     // Interrupt waiting to handle new node
     if (rcl_trigger_guard_condition(&interrupt_guard_condition_) != RCL_RET_OK) {
@@ -148,17 +153,21 @@ void
 Executor::remove_node(rclcpp::node_interfaces::NodeBaseInterface::SharedPtr node_ptr, bool notify)
 {
   bool node_removed = false;
-  weak_nodes_.erase(
-    std::remove_if(
-      weak_nodes_.begin(), weak_nodes_.end(),
-      [&](rclcpp::node_interfaces::NodeBaseInterface::WeakPtr & i)
   {
-        bool matched = (i.lock() == node_ptr);
+    auto node_it = weak_nodes_.begin();
-        node_removed |= matched;
+    auto gc_it = guard_conditions_.begin();
-        return matched;
+    while (node_it != weak_nodes_.end()) {
+      bool matched = (node_it->lock() == node_ptr);
+      if (matched) {
+        node_it = weak_nodes_.erase(node_it);
+        gc_it = guard_conditions_.erase(gc_it);
+        node_removed = true;
+      } else {
+        ++node_it;
+        ++gc_it;
+      }
+    }
   }
-    )
-  );
   std::atomic_bool & has_executor = node_ptr->get_associated_with_executor_atomic();
   has_executor.store(false);
   if (notify) {
@@ -420,15 +429,18 @@ Executor::wait_for_work(std::chrono::nanoseconds timeout)
 
   // Clean up any invalid nodes, if they were detected
   if (has_invalid_weak_nodes) {
-    weak_nodes_.erase(
+    auto node_it = weak_nodes_.begin();
-      remove_if(
+    auto gc_it = guard_conditions_.begin();
-        weak_nodes_.begin(), weak_nodes_.end(),
+    while (node_it != weak_nodes_.end()) {
-        [](rclcpp::node_interfaces::NodeBaseInterface::WeakPtr i)
+      if (node_it->expired()) {
-        {
+        node_it = weak_nodes_.erase(node_it);
-          return i.expired();
+        memory_strategy_->remove_guard_condition(*gc_it);
+        gc_it = guard_conditions_.erase(gc_it);
+      } else {
+        ++node_it;
+        ++gc_it;
+      }
     }
-      )
-    );
   }
   // clear wait set
   if (rcl_wait_set_clear(&wait_set_) != RCL_RET_OK) {

rclcpp/src/rclcpp/memory_strategy.cpp

@@ -20,7 +20,7 @@ using rclcpp::memory_strategy::MemoryStrategy;
 rclcpp::SubscriptionBase::SharedPtr
 MemoryStrategy::get_subscription_by_handle(
   std::shared_ptr<const rcl_subscription_t> subscriber_handle,
-  const WeakNodeVector & weak_nodes)
+  const WeakNodeList & weak_nodes)
 {
   for (auto & weak_node : weak_nodes) {
     auto node = weak_node.lock();
@@ -51,7 +51,7 @@ MemoryStrategy::get_subscription_by_handle(
 rclcpp::ServiceBase::SharedPtr
 MemoryStrategy::get_service_by_handle(
   std::shared_ptr<const rcl_service_t> service_handle,
-  const WeakNodeVector & weak_nodes)
+  const WeakNodeList & weak_nodes)
 {
   for (auto & weak_node : weak_nodes) {
     auto node = weak_node.lock();
@@ -77,7 +77,7 @@ MemoryStrategy::get_service_by_handle(
 rclcpp::ClientBase::SharedPtr
 MemoryStrategy::get_client_by_handle(
   std::shared_ptr<const rcl_client_t> client_handle,
-  const WeakNodeVector & weak_nodes)
+  const WeakNodeList & weak_nodes)
 {
   for (auto & weak_node : weak_nodes) {
     auto node = weak_node.lock();
@@ -103,7 +103,7 @@ MemoryStrategy::get_client_by_handle(
 rclcpp::node_interfaces::NodeBaseInterface::SharedPtr
 MemoryStrategy::get_node_by_group(
   rclcpp::callback_group::CallbackGroup::SharedPtr group,
-  const WeakNodeVector & weak_nodes)
+  const WeakNodeList & weak_nodes)
 {
   if (!group) {
     return nullptr;
@@ -126,7 +126,7 @@ MemoryStrategy::get_node_by_group(
 rclcpp::callback_group::CallbackGroup::SharedPtr
 MemoryStrategy::get_group_by_subscription(
   rclcpp::SubscriptionBase::SharedPtr subscription,
-  const WeakNodeVector & weak_nodes)
+  const WeakNodeList & weak_nodes)
 {
   for (auto & weak_node : weak_nodes) {
     auto node = weak_node.lock();
@@ -152,7 +152,7 @@ MemoryStrategy::get_group_by_subscription(
 rclcpp::callback_group::CallbackGroup::SharedPtr
 MemoryStrategy::get_group_by_service(
   rclcpp::ServiceBase::SharedPtr service,
-  const WeakNodeVector & weak_nodes)
+  const WeakNodeList & weak_nodes)
 {
   for (auto & weak_node : weak_nodes) {
     auto node = weak_node.lock();
@@ -178,7 +178,7 @@ MemoryStrategy::get_group_by_service(
 rclcpp::callback_group::CallbackGroup::SharedPtr
 MemoryStrategy::get_group_by_client(
   rclcpp::ClientBase::SharedPtr client,
-  const WeakNodeVector & weak_nodes)
+  const WeakNodeList & weak_nodes)
 {
   for (auto & weak_node : weak_nodes) {
     auto node = weak_node.lock();
@@ -204,7 +204,7 @@ MemoryStrategy::get_group_by_client(
 rclcpp::callback_group::CallbackGroup::SharedPtr
 MemoryStrategy::get_group_by_waitable(
   rclcpp::Waitable::SharedPtr waitable,
-  const WeakNodeVector & weak_nodes)
+  const WeakNodeList & weak_nodes)
 {
   for (auto & weak_node : weak_nodes) {
     auto node = weak_node.lock();

rclcpp/test/test_executor.cpp

@@ -60,3 +60,10 @@ TEST_F(TestExecutors, detachOnDestruction) {
     EXPECT_NO_THROW(executor.add_node(node));
   }
 }
+
+// Make sure that the executor can automatically remove expired nodes correctly
+TEST_F(TestExecutors, addTemporaryNode) {
+  rclcpp::executors::SingleThreadedExecutor executor;
+  executor.add_node(std::make_shared<rclcpp::Node>("temporary_node"));
+  EXPECT_NO_THROW(executor.spin_some());
+}

rclcpp/test/test_find_weak_nodes.cpp

@@ -36,15 +36,15 @@ TEST_F(TestFindWeakNodes, allocator_strategy_with_weak_nodes) {
     rclcpp::memory_strategies::allocator_memory_strategy::AllocatorMemoryStrategy<>>();
   auto existing_node = rclcpp::Node::make_shared("existing_node");
   auto dead_node = rclcpp::Node::make_shared("dead_node");
-  rclcpp::memory_strategy::MemoryStrategy::WeakNodeVector weak_nodes;
+  rclcpp::memory_strategy::MemoryStrategy::WeakNodeList weak_nodes;
   weak_nodes.push_back(existing_node->get_node_base_interface());
   weak_nodes.push_back(dead_node->get_node_base_interface());
 
   // AND
   // Delete dead_node, creating a dangling pointer in weak_nodes
   dead_node.reset();
-  ASSERT_FALSE(weak_nodes[0].expired());
+  ASSERT_FALSE(weak_nodes.front().expired());
-  ASSERT_TRUE(weak_nodes[1].expired());
+  ASSERT_TRUE(weak_nodes.back().expired());
 
   // WHEN
   bool has_invalid_weak_nodes = memory_strategy->collect_entities(weak_nodes);
@@ -64,11 +64,11 @@ TEST_F(TestFindWeakNodes, allocator_strategy_no_weak_nodes) {
     rclcpp::memory_strategies::allocator_memory_strategy::AllocatorMemoryStrategy<>>();
   auto existing_node1 = rclcpp::Node::make_shared("existing_node1");
   auto existing_node2 = rclcpp::Node::make_shared("existing_node2");
-  rclcpp::memory_strategy::MemoryStrategy::WeakNodeVector weak_nodes;
+  rclcpp::memory_strategy::MemoryStrategy::WeakNodeList weak_nodes;
   weak_nodes.push_back(existing_node1->get_node_base_interface());
   weak_nodes.push_back(existing_node2->get_node_base_interface());
-  ASSERT_FALSE(weak_nodes[0].expired());
+  ASSERT_FALSE(weak_nodes.front().expired());
-  ASSERT_FALSE(weak_nodes[1].expired());
+  ASSERT_FALSE(weak_nodes.back().expired());
 
   // WHEN
   bool has_invalid_weak_nodes = memory_strategy->collect_entities(weak_nodes);