Outsource functions to separate Task (ESPAsyncWebServer) | ESP32

Projects Programming
1

In my project I use the ESPAsyncWebServer. If an WebServer-event occurs, I need to call functions. These functions are fairly large and also contain some code, which require some time to execute. Due to that I sometimes receive Watchdog timeouts.

To fix this, I would like to outsource the functions, so they no longer run in the same task, as the webserver.

Here is a short code snippet as an example:

void onEvent(AsyncWebSocket       *server,
             AsyncWebSocketClient *client,
             AwsEventType          type,
             void                 *arg,
             uint8_t              *data,
             size_t                len) {

    switch (type) {
        case WS_EVT_CONNECT:
            Serial.printf("WebSocket client #%u connected from %s\n", client->id(), client->remoteIP().toString().c_str());
            break;
        case WS_EVT_DISCONNECT:
            Serial.printf("WebSocket client #%u disconnected\n", client->id());
            break;
        case WS_EVT_DATA:
            handleWebSocketMessage(arg, data, len);
            break;
        case WS_EVT_PONG:
        case WS_EVT_ERROR:
            break;
    }
}

void handleWebSocketMessage(void *arg, uint8_t *data, size_t len) {
    AwsFrameInfo *info = (AwsFrameInfo*)arg;
    if (info->final && info->index == 0 && info->len == len && info->opcode == WS_TEXT) {
        data[len] = 0;
        if (strcmp((char*)data, "toggle1") == 0) {            
            function1();
        }
        if (strcmp((char*)data, "toggle2") == 0) {            
            function2();
        }
         if (strcmp((char*)data, "toggle3") == 0) {            
            function3();
        }
...
    }
}

The functions: function1(), function2(), function2() should run on a different task and should be executed if they are called by the handleWebSocketMessage-Function.

I don’t want to use flags, as the functions also contain several parameters, which are passed by the “uint8_t *data”-Element (via ArduinoJson).

Basically, all I want to achieve, is that the function “handleWebSocketMessage” don’t has to wait for the execution of the individual functions.

Has anybody an idea how to achieve that?

2

you probably need to duplicate the payload to make it available to your new task as the Events ends, its likely that the void *arg and uint8_t *data will no longer be maintained

there are on line examples, here is one (random hit)

3

What I don’t understand yet, is how I would initiate the execution of the function in the main task and how I would make sure they only run once.
Is it possible leave the infinite for-loop out, so that the task only runs once? And start it again in the main task if it is needed?

4

If the task is not coded to run as a loop such as a

 while(1) or a for(;;)

then the task will exit when it gets to the end of the code.

At the end of the called run-one-time-task use vTaskDelete( NULL );, which will flag the task to the OS to clean up memory used by the calling task.

Use log_i( " high watermark % d", uxTaskGetStackHighWaterMark( NULL ) ); to get stack space used by the task.

I use the xTaskCreatePinnedToCore( task, "task string name", somenumberoframbytes, NULL, some priority level, NULL, 1 ); function to create a task. Just define a task creation freeRTOS macro, upon the code execution of the task creation macro, the newly created task will spawn, run, and without a loop, die.

5

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