Event subsystem

Main application works in a RTOS task. Leaves works in dedicated tasks. Networking and other ESP-IDF services has their own tasks as well. This means that all communication through those components must be done using the RTOS task messaging features and higher ESP-IDF abstractions.

GrowNode uses Event Loop library from ESP-IDF to list, subscribe and publish events. It declares one base event GN_BASE_EVENT and a gn_event_id_t enumeration where all event types are listed.

Subscribing events

In order to grab a specific event you can rely on ESP-IDF event loop functions. In order to recall the proper event loop from a Leaf or Node, gn_leaf_get_event_loop() and gn_node_get_event_loop() are provided. See example:

//register for events
esp_event_handler_instance_register_with(gn_leaf_get_event_loop(leaf_config), GN_BASE_EVENT,  
    GN_EVENT_ANY_ID, gn_leaf_led_status_event_handler, leaf_config, NULL);

This code creates a subscription for all events (GN_EVENT_ANY_ID), calling gn_leaf_led_status_event_handler callback once an event is triggered, and pass the leaf_config pointer in the context.

Those functions returns currently the same event loop, different implementations are made for future needs.

Publishing events

Event are published using straight esp event loop functionalities:

esp_event_post_to(event_loop, GN_BASE_EVENT,
        GN_NET_CONNECTED_EVENT, NULL, 0,
        portMAX_DELAY);

Listening for event

Event callbacks shall implement esp_event_handler_t syntax. Payload is dependent on the event type triggered:

void gn_pump_control_task_event_handler(void *handler_args,
        esp_event_base_t base, int32_t event_id, void *event_data) {

    gn_leaf_parameter_event_t *evt = (gn_leaf_parameter_event_t*) event_data;
    switch (event_id) {
    case GN_LEAF_PARAM_CHANGED_EVENT:
...

Acquiring events in leaf code

Events addressed to leaves from other leaves and from network has a special, direct way to be processed, that improves GrowNode engine performances, using RTOS queues. Leaves that has just to wait for an event can implement an infinite loop where an xQueueReceive() function waits for events for a specific time window. If no events are presents in the queue, the queue releases the control to the leaf:

gn_leaf_parameter_event_t evt;

if (xQueueReceive(gn_leaf_get_event_queue(leaf_config), &evt, 
    pdMS_TO_TICKS(100)) == pdPASS) {

    //event arrived for this node
    switch (evt.id) {

        //parameter change
        case GN_LEAF_PARAM_CHANGE_REQUEST_EVENT:

        ESP_LOGD(TAG, "request to update param %s, data = '%s'",
            evt.param_name, evt.data);
    ...