Behavior of micro-ROS when losing the connection to the micro-ROS-agent

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Hello,

I am working on an application where I want to use micro-ROS on an ESP32-S3. In the application I need to realize a real-time controller with a cycle of 10 ms. As micro-ROS is advertised as a solution for real-time applications, I expected that I can use the micro-ROS timer for my controller and for understanding I firstly tested the behavior of micro-ROS a little bit.

- Hardware description: ESP32-S3
- RTOS: FreeRTOS
- Installation type: micro-ROS-ESP-IDF component in a PlatformIO project
micro-ROS-agent on an Ubuntu 20.04
- ROS2 and MicroROS Verison: Galactic

### Steps to reproduce the issue
For testing I expanded the int32_publisher example with a second timer. This timer only sets a led on or off at each callback. The timer 1 (publisher) is set to a cycle time of 1000 ms and the timer 2 (led) is set to a cycle time of 10 ms.

Then I tested my example and while the micro-ROS-agent was active it worked great. The led shines constantly so the timer callback seems to be fast and constant. Also the printf output is shown every second.
After that I tested the behavior of the timer when losing the agent by disabling the Wi-Fi of my Ubuntu. But after the ESP32 lost the connection to the agent, micro-ROS did not behave like I expected.
The printf output is still displayed every 1000 ms. But also it prints “Failed status on line 36: 1. Continuing” every 1000 ms. My conclusion is that the publisher cannot publish anymore because it needs an agent. Am I understanding this right?
Also I noticed that the callback of my second timer does not work anymore with the right frequency after stopping the agent. The led blinks with a frequency of 1 Hz. This is way too slow for my application because the controller always needs to be called with a constant frequency.
After I activated the Wi-Fi, the publisher and the second timer worked again correctly.

### Expected behavior
The timer frequency is independend wether the micro-ROS-agent ist available or not.
The timer 2 is called every 10 ms even if the micro-ROS-agent is not connected.

### Actual behavior
The callback frequency of the timer 2 drops to 1 Hz instead of the wanted 100 Hz, while the agent is not connected .

### Additional information
Did I do something wrong in my application? Is it possible to make the micro-ROS-timer work independently from the micro-ROS-agent or do I need to do a workaroud like a using a GPT Timer?

Thank you for your reply.

```c
#include
#include
#include

#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "esp_log.h"
#include "esp_system.h"

#include
#include
#include
#include
#include
#include

#ifdef CONFIG_MICRO_ROS_ESP_XRCE_DDS_MIDDLEWARE
#include
#endif

#define RCCHECK(fn) { rcl_ret_t temp_rc = fn; if((temp_rc != RCL_RET_OK)){printf("Failed status on line %d: %d. Aborting.\n",__LINE__,(int)temp_rc);vTaskDelete(NULL);}}
#define RCSOFTCHECK(fn) { rcl_ret_t temp_rc = fn; if((temp_rc != RCL_RET_OK)){printf("Failed status on line %d: %d. Continuing.\n",__LINE__,(int)temp_rc);}}

#include "driver/gpio.h"
#define led_green (gpio_num_t) 48
bool toogle_led_green = 0;

rcl_publisher_t publisher;
std_msgs__msg__Int32 msg;

void timer_callback_1(rcl_timer_t * timer, int64_t last_call_time)
{
RCLC_UNUSED(last_call_time);
if (timer != NULL) {
printf("Publishing: %d\n", msg.data);
RCSOFTCHECK(rcl_publish(&publisher, &msg, NULL));
msg.data++;
}
}

void timer_callback_2(rcl_timer_t * timer, int64_t last_call_time)
{
RCLC_UNUSED(last_call_time);
if (timer != NULL) {
gpio_set_level(led_green, toogle_led_green);
toogle_led_green = !toogle_led_green;
}
}

void micro_ros_task(void * arg)
{
rcl_allocator_t allocator = rcl_get_default_allocator();
rclc_support_t support;

rcl_init_options_t init_options = rcl_get_zero_initialized_init_options();
RCCHECK(rcl_init_options_init(&init_options, allocator));

#ifdef CONFIG_MICRO_ROS_ESP_XRCE_DDS_MIDDLEWARE
rmw_init_options_t* rmw_options = rcl_init_options_get_rmw_init_options(&init_options);

// Static Agent IP and port can be used instead of autodisvery.
RCCHECK(rmw_uros_options_set_udp_address(CONFIG_MICRO_ROS_AGENT_IP, CONFIG_MICRO_ROS_AGENT_PORT, rmw_options));
//RCCHECK(rmw_uros_discover_agent(rmw_options));
#endif

// create init_options
RCCHECK(rclc_support_init_with_options(&support, 0, NULL, &init_options, &allocator));

// create node
rcl_node_t node;
RCCHECK(rclc_node_init_default(&node, "esp32_int32_publisher", "", &support));

// create publisher
RCCHECK(rclc_publisher_init_default(
&publisher,
&node,
ROSIDL_GET_MSG_TYPE_SUPPORT(std_msgs, msg, Int32),
"freertos_int32_publisher"));

// create timer,
rcl_timer_t timer_1;
const unsigned int timer_timeout_1 = 1000;
RCCHECK(rclc_timer_init_default(
&timer_1,
&support,
RCL_MS_TO_NS(timer_timeout_1),
timer_callback_1));

rcl_timer_t timer_2;
const unsigned int timer_timeout_2 = 10;
RCCHECK(rclc_timer_init_default(
&timer_2,
&support,
RCL_MS_TO_NS(timer_timeout_2),
timer_callback_2));

// create executor
rclc_executor_t executor;
RCCHECK(rclc_executor_init(&executor, &support.context, 2, &allocator));
RCCHECK(rclc_executor_add_timer(&executor, &timer_1));
RCCHECK(rclc_executor_add_timer(&executor, &timer_2));

msg.data = 0;

while(1){
rclc_executor_spin_some(&executor, RCL_MS_TO_NS(1));
//usleep(10000);
}

// free resources
RCCHECK(rcl_publisher_fini(&publisher, &node));
RCCHECK(rcl_node_fini(&node));

vTaskDelete(NULL);
}

void app_main(void)
{
//Initialize LED
gpio_pad_select_gpio(led_green);
gpio_set_direction(led_green, GPIO_MODE_OUTPUT);
gpio_set_level(led_green, 0);

#if defined(CONFIG_MICRO_ROS_ESP_NETIF_WLAN) || defined(CONFIG_MICRO_ROS_ESP_NETIF_ENET)
ESP_ERROR_CHECK(uros_network_interface_initialize());
#endif

//pin micro-ros task in APP_CPU to make PRO_CPU to deal with wifi:
xTaskCreate(micro_ros_task,
"uros_task",
CONFIG_MICRO_ROS_APP_STACK,
NULL,
CONFIG_MICRO_ROS_APP_TASK_PRIO,
NULL);
}
```

Bắt đầu với ví dụ int32_publisher mở rộng và vòng lặp micro_ros_task, sau đó kiểm tra timer_callback_1, timer_callback_2 và lời gọi rclc_executor_spin_some trong khi tái hiện tình trạng mất agent. So sánh thời điểm callback và đầu ra lỗi publish khi agent được kết nối và khi bị ngắt kết nối; hoàn thành nghĩa là ghi lại hoặc xác nhận hành vi timer dự kiến và xác định ranh giới thực thi liên quan.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.