Message callback

Understand how to use message callback to handle messages.

Read time 2 minutes

Last updated 8 months ago

When you initialize the Vivox SDK, you need to set up your implementation to handle SDK messages. Using a callback method is the suggested best practice. This simplifies your game logic by only responding to messages when they occur, rather than using a polling loop that might be idle most of the time.

The callback is a parameter for

vx_sdk_config_t

, which is shown in the following

VxcTypes.h

example:


// When the SDK message callback is called, call vx_get_message() until there are no more messages.    void (*pf_sdk_message_callback)(void *callback_handle);

The following example is built on code from the SDKSampleApp with extra details on using OnSdkMessageAvailable on a ListenerThread:


static vx_sdk_config_t MakeConfig(const SDKSampleApp &app, unsigned int default_codecs_mask, vx_log_level log_level = log_error){    vx_sdk_config_t config;    vx_get_default_config3(&config, sizeof(config));    config.pf_logging_callback = OnLog;    config.pf_sdk_message_callback = OnSdkMessageAvailable;}void OnSdkMessageAvailable(void *callbackHandle){    SDKSampleApp *app = reinterpret_cast<SDKSampleApp *>(callbackHandle);    app->set_event(m_messageAvailableEvent);}void SDKSampleApp::ListenerThread(){    for (; m_started;)         // Pulls a message from the queue. If no message found, waits until notified, then tries again.    {        wait_event(m_messageAvailableEvent, -1);        for (;;)         {            vx_message_base_t *msg = NULL;            vx_get_message(&msg);               // Type of message, and then type of the Event or Response is discovered, and the    // appropriate call is made to process that message type.                      if (msg == NULL)             {                break;            }            Lock();            HandleMessage(msg);            Unlock();            vx_destroy_message(msg);        }    }    set_event(m_listenerThreadTerminatedEvent);}

Note

The Vivox SDKSampleApp shows the use of a mutex while processing messages (the

HandleMessage()

function). This is a requirement of the SDKSampleApp, not the Vivox SDK. A mutex is only needed if your implementation requires it by design.

Note

Messages can be processed on the same thread as the callback or on a different thread.

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