MQTT keepalive和reconnect

博客提供了MQTT和Linux相关的参考链接,可帮助读者获取更多关于MQTT协议在Linux系统下的相关信息,为信息技术领域中涉及这两方面的学习和研究提供便利。

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/** * @file * @brief Implements the functionality of MQTT-C. * @note The only files that are included are mqtt.h and mqtt_pal.h. * * @cond Doxygen_Suppress */ enum MQTTErrors mqtt_sync(struct mqtt_client *client) { /* Recover from any errors */ enum MQTTErrors err; int reconnecting = 0; MQTT_PAL_MUTEX_LOCK(&client->mutex); if (client->error != MQTT_ERROR_RECONNECTING && client->error != MQTT_OK && client->reconnect_callback != NULL) { client->reconnect_callback(client, &client->reconnect_state); if (client->error != MQTT_OK) { client->error = MQTT_ERROR_RECONNECT_FAILED; /* normally unlocked during CONNECT */ MQTT_PAL_MUTEX_UNLOCK(&client->mutex); } err = client->error; if (err != MQTT_OK) return err; } else { /* mqtt_reconnect will have queued the disconnect packet - that needs to be sent and then call reconnect */ if (client->error == MQTT_ERROR_RECONNECTING) { reconnecting = 1; client->error = MQTT_OK; } MQTT_PAL_MUTEX_UNLOCK(&client->mutex); } /* Call inspector callback if necessary */ if (client->inspector_callback != NULL) { MQTT_PAL_MUTEX_LOCK(&client->mutex); err = client->inspector_callback(client); MQTT_PAL_MUTEX_UNLOCK(&client->mutex); if (err != MQTT_OK) return err; } /* Call receive */ err = (enum MQTTErrors)__mqtt_recv(client); if (err != MQTT_OK) return err; /* Call send */ err = (enum MQTTErrors)__mqtt_send(client); /* mqtt_reconnect will essentially be a disconnect if there is no callback */ if (reconnecting && client->reconnect_callback != NULL) { MQTT_PAL_MUTEX_LOCK(&client->mutex); client->reconnect_callback(client, &client->reconnect_state); } return err; }
03-17
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