make stack size and priority configurable

Kconfig

@@ -0,0 +1,11 @@
+menu "esp-mqtt"
+
+config ESP_MQTT_TASK_STACK_SIZE
+    int "MQTT background process task stack size"
+    default 4096
+
+config ESP_MQTT_TASK_STACK_PRIORITY
+    int "MQTT background process task priority"
+    default 5
+
+endmenu

esp_mqtt.c

@@ -276,7 +276,8 @@ void esp_mqtt_start(const char *host, unsigned int port, const char *client_id,
 
   // create mqtt thread
   ESP_LOGI(ESP_MQTT_LOG_TAG, "esp_mqtt_start: create task");
-  xTaskCreatePinnedToCore(esp_mqtt_process, "esp_mqtt", 4096, NULL, 5, &esp_mqtt_task, 1);
+  xTaskCreatePinnedToCore(esp_mqtt_process, "esp_mqtt", CONFIG_ESP_MQTT_TASK_STACK_SIZE, NULL,
+                          CONFIG_ESP_MQTT_TASK_STACK_PRIORITY, &esp_mqtt_task, 1);
 
   // set local flag
   esp_mqtt_running = true;

test/sdkconfig

@@ -91,6 +91,12 @@ CONFIG_OPTIMIZATION_LEVEL_DEBUG=y
 # CONFIG_BT_ENABLED is not set
 CONFIG_BT_RESERVE_DRAM=0
 
+#
+# esp-mqtt
+#
+CONFIG_ESP_MQTT_TASK_STACK_SIZE=4096
+CONFIG_ESP_MQTT_TASK_STACK_PRIORITY=5
+
 #
 # ESP32-specific
 #