FS api calls fail when initiated from within the HTTP callback function

I have discovered a workaround thanks to the camera_application example in he SDK.

You create a global variable that triggers the initiation of a function call from within the main program loop.

int configTrigger = 0; // Global variable

void saveConfig()
{
    // Perform FS API calls
}

void sl_HttpServerCallback(SlHttpServerEvent_t *pEvent, SlHttpServerResponse_t *pResponse)
{
    switch (pEvent->Event)
    {
        case SL_NETAPP_HTTPGETTOKENVALUE:  // HTTP GET recieved
        {
	     // GET request code here
        }
        break;

        case SL_NETAPP_HTTPPOSTTOKENVALUE:  // HTTP POST received
        {
	    //saveConfig(); <-- This will cause the problem
	    
            configTrigger = 1; // This triggers the call from with the main program loop
        }
        break;

        default:
        break;
    }
}

void main()
{
    // application connectivity code here

    // Main program loop
    while(1)
    {
        // Saves config data when requested from a HTTP POST from within the HTTP Callback
        if (configTrigger)
        {
        	saveConfig();
        	configTrigger = 0;
        }
    }
}

Hopefully this should save you some time in developing code.

Glenn.

Hi Glenn,

Event handlers including the HTTP callback cannot activate another SimpleLink API from their context.

You are correct and indeed in these kind of calls a dead lock might occur.

We will try to emphasize this point better in next releases.

Barak