support for esp event loop library while keeping backward compatible mode if callback configured

README.md

@@ -19,9 +19,21 @@
 Please refer to instructions in [ESP-IDF](https://github.com/espressif/esp-idf)
 
 ## Documentation
-Please refer to the standard [ESP-IDF](https://github.com/espressif/esp-idf) documentation here https://github.com/espressif/esp-idf/blob/master/docs/en/api-reference/protocols/mqtt.rst
+
+* Please refer to the standard [ESP-IDF](https://github.com/espressif/esp-idf), documentation for the latest version: https://docs.espressif.com/projects/esp-idf/
+
+* Documentation of ESP-MQTT API: https://docs.espressif.com/projects/esp-idf/en/latest/api-reference/protocols/mqtt.html
 
 ## License
+
 - MQTT Package - [Stephen Robinson - contiki-mqtt](https://github.com/esar/contiki-mqtt)
 - Others [@tuanpmt](https://twitter.com/tuanpmt)
 Apache License
+
+## Older IDF verisons
+
+For [ESP-IDF](https://github.com/espressif/esp-idf) versions prior to IDFv3.2, please  clone as a component of [ESP-IDF](https://github.com/espressif/esp-idf):
+```
+git submodule add https://github.com/espressif/esp-mqtt.git components/espmqtt
+```
+and checkout the [ESP-MQTT_FOR_IDF_3.1](https://github.com/espressif/esp-mqtt/tree/ESP-MQTT_FOR_IDF_3.1) tag

include/mqtt_client.h

@@ -13,6 +13,7 @@
 #include "esp_err.h"
 
 #include "mqtt_config.h"
+#include "esp_event.h"
 
 #ifdef __cplusplus
 extern "C" {
@@ -85,7 +86,8 @@ typedef esp_err_t (* mqtt_event_callback_t)(esp_mqtt_event_handle_t event);
  * MQTT client configuration structure
  */
 typedef struct {
-    mqtt_event_callback_t event_handle;     /*!< handle for MQTT events */
+    mqtt_event_callback_t event_handle;     /*!< handle for MQTT events as a callback in legacy mode */
+    esp_event_loop_handle_t event_loop_handle; /*!< handle for MQTT event loop library */
     const char *host;                       /*!< MQTT server domain (ipv4 as string) */
     const char *uri;                        /*!< Complete MQTT broker URI */
     uint32_t port;                          /*!< MQTT server port */
@@ -237,6 +239,19 @@ esp_err_t esp_mqtt_client_destroy(esp_mqtt_client_handle_t client);
  */
 esp_err_t esp_mqtt_set_config(esp_mqtt_client_handle_t client, const esp_mqtt_client_config_t *config);
 
+/**
+ * @brief Registers mqtt event
+ *
+ * @param client            mqtt client handle
+ * @param event             event type
+ * @param event_handler     hanlder callback
+ * @param event_handler_arg handlers context
+ *
+ * @return ESP_ERR_NO_MEM if failed to allocate
+ *         ESP_OK on success
+ */
+esp_err_t esp_mqtt_client_register_event(esp_mqtt_client_handle_t client, esp_mqtt_event_id_t event, esp_event_handler_t event_handler, void* event_handler_arg);
+
 #ifdef __cplusplus
 }
 #endif //__cplusplus

mqtt_client.c

@@ -12,6 +12,7 @@
 
 /* using uri parser */
 #include "http_parser.h"
+#include "esp_event_loop.h"
 
 #ifdef MQTT_DISABLE_API_LOCKS
 # define MQTT_API_LOCK(c)
@@ -27,7 +28,14 @@
 
 static const char *TAG = "MQTT_CLIENT";
 
-typedef struct mqtt_state {
+/**
+ * @brief Define of MQTT Event base
+ *
+ */
+ESP_EVENT_DEFINE_BASE(MQTT_EVENTS);
+
+typedef struct mqtt_state
+{
     mqtt_connect_info_t *connect_info;
     uint8_t *in_buffer;
     uint8_t *out_buffer;
@@ -45,6 +53,7 @@ typedef struct mqtt_state {
 
 typedef struct {
     mqtt_event_callback_t event_handle;
+    esp_event_loop_handle_t event_loop_handle;
     int task_stack;
     int task_prio;
     char *uri;
@@ -214,6 +223,12 @@ esp_err_t esp_mqtt_set_config(esp_mqtt_client_handle_t client, const esp_mqtt_cl
 
     if (config->event_handle) {
         cfg->event_handle = config->event_handle;
+    } else {
+        esp_event_loop_args_t no_task_loop = {
+            .queue_size = 1,
+            .task_name = NULL,
+        };
+        esp_event_loop_create(&no_task_loop, &cfg->event_loop_handle);
     }
 
     if (config->refresh_connection_after_ms) {
@@ -540,8 +555,10 @@ static esp_err_t esp_mqtt_dispatch_event(esp_mqtt_client_handle_t client)
 
     if (client->config->event_handle) {
         return client->config->event_handle(&client->event);
+    } else {
+        esp_event_post_to(client->config->event_loop_handle, MQTT_EVENTS, client->event.event_id, &client->event, sizeof(client->event), portMAX_DELAY);
+        return esp_event_loop_run(client->config->event_loop_handle, 0);
     }
-    return ESP_FAIL;
 }
 
 static esp_err_t deliver_publish(esp_mqtt_client_handle_t client)
@@ -1289,3 +1306,15 @@ cannot_publish:
 }
 
 
+esp_err_t esp_mqtt_client_register_event(esp_mqtt_client_handle_t client, esp_mqtt_event_id_t event, esp_event_handler_t event_handler, void* event_handler_arg)
+{
+    if (client == NULL) {
+        return ESP_ERR_INVALID_ARG;
+    }
+    if (client->config->event_handle) {
+        ESP_LOGW(TAG, "Registering event loop while event callback is not null, clearing callback");
+        client->config->event_handle = NULL;
+    }
+
+    return esp_event_handler_register_with(client->config->event_loop_handle, MQTT_EVENTS, event, event_handler, event_handler_arg);
+}