[lwip-users] Knowing when TCP data has been sent

[Sägesser Walter]

Hi

 

In the raw API there is a dedecated callback that tells me that the data is out and confirmed. I have been looking for something similar in the netconn API (in order to know when a buffer used in netconn_write can be freed without having to use NETCONN_COPY). I tried creating a netconn using  

"xNetConn = netconn_new_with_callback ( NETCONN_TCP, NetConnClientCallback );"    // netconn kept alive until no transfer for a few seconds

 

// called in the context of the TCP thread

statuc void NetConnClientCallback ( TNetConn aConn, ENetEvent aEv, UInt16 aLen )
{
    if ( aEv == NETCONN_EVT_SENDPLUS )
    {
        mClientSendCnt -= aLen;

        if ( mClientSendCnt == 0 )
            RTOS_SemPost ( gSemTcpClnHandle );
    }
} // NetConnClientCallback

Basically it works, i.e. the semaphore is eventually posted, but unbearably slow (delay of ca. 200ms for each frame). Without this callback, using NETCONN_COPY for netconn_write, the throughput is at least 120 times better. Thus I conclude that I have misused the callback function for something it is not designed for. On the other hand I do not find a better way to get a "done" trigger. Is there a better way or do I have to copy the outgoing data (which would violate the concept of a non-copy interface)?

 

Walter

 

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