client: Add support for user events

Also supporting configurable queue size for the internal event loop.

Closes https://github.com/espressif/esp-mqtt/issues/230

include/mqtt_client.h

@@ -82,6 +82,10 @@ typedef enum esp_mqtt_event_id_t {
                                   - Additional context: msg_id (id of the deleted
                                 message).
                                   */
+    MQTT_USER_EVENT,            /*!< Custom event used to queue tasks into mqtt event handler
+                                 All fields from the esp_mqtt_event_t type could be used to pass
+                                 an additional context data to the handler.
+                                 */
 } esp_mqtt_event_id_t;
 
 /**
@@ -569,6 +573,16 @@ esp_err_t esp_mqtt_client_unregister_event(esp_mqtt_client_handle_t client, esp_
  */
 int esp_mqtt_client_get_outbox_size(esp_mqtt_client_handle_t client);
 
+/**
+ * @brief Dispatch user event to the mqtt internal event loop
+ *
+ * @param client            *MQTT* client handle
+ * @param event             *MQTT* event handle structure
+ * @return ESP_OK on success
+ *         ESP_ERR_TIMEOUT if the event couldn't be queued (ref also CONFIG_MQTT_EVENT_QUEUE_SIZE)
+ */
+esp_err_t esp_mqtt_dispatch_custom_event(esp_mqtt_client_handle_t client, esp_mqtt_event_t *event);
+
 #ifdef __cplusplus
 }
 #endif //__cplusplus

lib/include/mqtt_client_priv.h

@@ -9,6 +9,7 @@
 
 #include <stdio.h>
 #include <stdlib.h>
+#include <stdatomic.h>
 #include "esp_err.h"
 #include "platform.h"
 
@@ -123,6 +124,9 @@ struct esp_mqtt_client {
     EventGroupHandle_t status_bits;
     SemaphoreHandle_t  api_lock;
     TaskHandle_t       task_handle;
+#if MQTT_EVENT_QUEUE_SIZE > 1
+    atomic_int         queued_events;
+#endif
 };
 
 bool esp_mqtt_set_if_config(char const *const new_config, char **old_config);

lib/include/mqtt_config.h

@@ -96,6 +96,11 @@
 #define MQTT_ENABLE_WS              CONFIG_MQTT_TRANSPORT_WEBSOCKET
 #define MQTT_ENABLE_WSS             CONFIG_MQTT_TRANSPORT_WEBSOCKET_SECURE
 
+#ifdef CONFIG_MQTT_EVENT_QUEUE_SIZE
+#define MQTT_EVENT_QUEUE_SIZE       CONFIG_MQTT_EVENT_QUEUE_SIZE
+#else
+#define MQTT_EVENT_QUEUE_SIZE       10
+#endif
 
 #define OUTBOX_MAX_SIZE             (4*1024)
 #endif

mqtt_client.c

@@ -765,7 +765,14 @@ static bool create_client_data(esp_mqtt_client_handle_t client)
 
 esp_mqtt_client_handle_t esp_mqtt_client_init(const esp_mqtt_client_config_t *config)
 {
-    esp_mqtt_client_handle_t client = calloc(1, sizeof(struct esp_mqtt_client));
+    esp_mqtt_client_handle_t client = heap_caps_calloc(1, sizeof(struct esp_mqtt_client),
+#if MQTT_EVENT_QUEUE_SIZE > 1
+                                        // if supporting multiple queued events, we keep track of them
+                                        // using atomic variable, so need to make sure it won't get allocated in PSRAM
+                                        MALLOC_CAP_INTERNAL | MALLOC_CAP_8BIT);
+#else
+                                        MALLOC_CAP_DEFAULT);
+#endif
     ESP_MEM_CHECK(TAG, client, return NULL);
     if (!create_client_data(client)) {
         goto _mqtt_init_failed;
@@ -776,10 +783,13 @@ esp_mqtt_client_handle_t esp_mqtt_client_init(const esp_mqtt_client_config_t *co
     }
 #ifdef MQTT_SUPPORTED_FEATURE_EVENT_LOOP
     esp_event_loop_args_t no_task_loop = {
-        .queue_size = 1,
+        .queue_size = MQTT_EVENT_QUEUE_SIZE,
         .task_name = NULL,
     };
     esp_event_loop_create(&no_task_loop, &client->config->event_loop_handle);
+#if MQTT_EVENT_QUEUE_SIZE > 1
+    atomic_init(&client->queued_events, 0);
+#endif
 #endif
 
     client->keepalive_tick = platform_tick_get_ms();
@@ -939,6 +949,17 @@ static esp_err_t esp_mqtt_dispatch_event_with_msgid(esp_mqtt_client_handle_t cli
     return esp_mqtt_dispatch_event(client);
 }
 
+esp_err_t esp_mqtt_dispatch_custom_event(esp_mqtt_client_handle_t client, esp_mqtt_event_t *event)
+{
+    esp_err_t ret = esp_event_post_to(client->config->event_loop_handle, MQTT_EVENTS, MQTT_USER_EVENT, event, sizeof(*event), 0);
+#if MQTT_EVENT_QUEUE_SIZE > 1
+    if (ret == ESP_OK) {
+        atomic_fetch_add(&client->queued_events, 1);
+    }
+#endif
+    return ret;
+}
+
 static esp_err_t esp_mqtt_dispatch_event(esp_mqtt_client_handle_t client)
 {
     client->event.client = client;
@@ -1447,6 +1468,34 @@ static void mqtt_delete_expired_messages(esp_mqtt_client_handle_t client)
     }
 }
 
+/**
+ * @brief When using multiple queued item, we'd like to reduce the poll timeout to proceed with event loop exacution
+ */
+static inline int max_poll_timeout(esp_mqtt_client_handle_t client, int max_timeout)
+{
+    return
+#if MQTT_EVENT_QUEUE_SIZE > 1
+            atomic_load(&client->queued_events) > 0 ? 10: max_timeout;
+#else
+            max_timeout;
+#endif
+}
+
+static inline void run_event_loop(esp_mqtt_client_handle_t client)
+{
+#if MQTT_EVENT_QUEUE_SIZE > 1
+    if (atomic_load(&client->queued_events) > 0) {
+            atomic_fetch_sub(&client->queued_events, 1);
+#else
+    {
+#endif
+        esp_err_t ret = esp_event_loop_run(client->config->event_loop_handle, 0);
+        if (ret != ESP_OK) {
+            ESP_LOGE(TAG, "Error in running event_loop %d", ret);
+        }
+    }
+}
+
 static void esp_mqtt_task(void *pv)
 {
     esp_mqtt_client_handle_t client = (esp_mqtt_client_handle_t) pv;
@@ -1470,6 +1519,7 @@ static void esp_mqtt_task(void *pv)
     xEventGroupClearBits(client->status_bits, STOPPED_BIT);
     while (client->run) {
         MQTT_API_LOCK(client);
+        run_event_loop(client);
         switch (client->state) {
         case MQTT_STATE_DISCONNECTED:
             break;
@@ -1571,7 +1621,7 @@ static void esp_mqtt_task(void *pv)
             }
             MQTT_API_UNLOCK(client);
             xEventGroupWaitBits(client->status_bits, RECONNECT_BIT, false, true,
-                                client->wait_timeout_ms / 2 / portTICK_PERIOD_MS);
+                                max_poll_timeout(client, client->wait_timeout_ms / 2 / portTICK_PERIOD_MS));
             // continue the while loop instead of break, as the mutex is unlocked
             continue;
         default:
@@ -1580,7 +1630,7 @@ static void esp_mqtt_task(void *pv)
         }
         MQTT_API_UNLOCK(client);
         if (MQTT_STATE_CONNECTED == client->state) {
-            if (esp_transport_poll_read(client->transport, MQTT_POLL_READ_TIMEOUT_MS) < 0) {
+            if (esp_transport_poll_read(client->transport, max_poll_timeout(client, MQTT_POLL_READ_TIMEOUT_MS)) < 0) {
                 ESP_LOGE(TAG, "Poll read error: %d, aborting connection", errno);
                 esp_mqtt_abort_connection(client);
             }