fix one subscription can wait_for_message twice (#1870)

Signed-off-by: Chen Lihui <[email protected]>

Author: Chen Lihui

rclcpp/include/rclcpp/wait_for_message.hpp

@@ -18,6 +18,8 @@
 #include <memory>
 #include <string>
 
+#include "rcpputils/scope_exit.hpp"
+
 #include "rclcpp/node.hpp"
 #include "rclcpp/visibility_control.hpp"
 #include "rclcpp/wait_set.hpp"
@@ -54,6 +56,7 @@ bool wait_for_message(
 
   rclcpp::WaitSet wait_set;
   wait_set.add_subscription(subscription);
+  RCPPUTILS_SCOPE_EXIT(wait_set.remove_subscription(subscription); );
   wait_set.add_guard_condition(gc);
   auto ret = wait_set.wait(time_to_wait);
   if (ret.kind() != rclcpp::WaitResultKind::Ready) {

rclcpp/test/rclcpp/test_wait_for_message.cpp

@@ -72,3 +72,38 @@ TEST(TestUtilities, wait_for_message_indefinitely) {
 
   ASSERT_FALSE(received);
 }
+
+TEST(TestUtilities, wait_for_message_twice_one_sub) {
+  rclcpp::init(0, nullptr);
+
+  auto node = std::make_shared<rclcpp::Node>("wait_for_message_node3");
+
+  using MsgT = test_msgs::msg::Strings;
+  auto pub = node->create_publisher<MsgT>("wait_for_message_topic", 10);
+  auto sub = node->create_subscription<MsgT>(
+    "wait_for_message_topic", 1, [](const std::shared_ptr<const MsgT>) {});
+
+  MsgT out1;
+  MsgT out2;
+  auto received = false;
+  auto wait = std::async(
+    [&]() {
+      auto ret = rclcpp::wait_for_message(out1, sub, node->get_node_options().context(), 5s);
+      EXPECT_TRUE(ret);
+      ret = rclcpp::wait_for_message(out2, sub, node->get_node_options().context(), 5s);
+      EXPECT_TRUE(ret);
+      received = true;
+    });
+
+  for (auto i = 0u; i < 10 && received == false; ++i) {
+    pub->publish(*get_messages_strings()[0]);
+    std::this_thread::sleep_for(1s);
+  }
+
+  ASSERT_NO_THROW(wait.get());
+  ASSERT_TRUE(received);
+  EXPECT_EQ(out1, *get_messages_strings()[0]);
+  EXPECT_EQ(out2, *get_messages_strings()[0]);
+
+  rclcpp::shutdown();
+}