Re: [lwip-users] Transfer Mibs of data over TCP

[Sylvain Rochet]

Hi,

On Mon, Apr 03, 2017 at 01:43:44PM +0000, Noam Weissman wrote:
> Hi,
> 
> Why not use the RAW API server that is in the contribution ?
> 
> I am not using it because am using my own modified code that was created 
> before the current version.
> As far as I know it works nicely and many are using it ☺
> 
> I have no problems accepting a large file 1MB… never had to accept a larger 
> file but I  do not think it makes
> any difference.
> 
> I think that if netbuf_next() fails you need to add some delay and try again.
> I mean add vTaskDelay(10) or similar and try again.
> 
> When you transfer large amount of data you may get into cases that the 
> network has some lag.
> In that case your netbuf_next() call nay fail.
> 
> Doing something like this:
> 
> #define READ_ERROR_DELAY          10
> #define READ_ERROR_TIMEOUT    500
> 
> err_t MyRead( params )
> {
>    Int RetVal , TotalTimeOut  = 0;
> 
>    Do
>    {
>       RetVal = netbuf_next();
> 
>       If(RetVal == (-1))
>       {
>           vTaskDelay(READ_ERROR_DELAY / portTICK_RATE_MS);
>           TotalTimeOut += READ_ERROR_DELAY;
>       }
>       else
>       {
>           break;
>       }
> 
>    } while(TotalTimeOut < READ_ERROR_TIMEOUT);
> 
> }
> 
> 
> The above function will try to read from the socket and if fails it will 
> delay for about 10 ms… that way you give
> the TCP and other system tasks time to run.
> 
> If the above is not an option due to system constrains you can adapt some 
> kind of state machine, per connection
> and use lwip own function sys_timeout to trigger for the above function or 
> similar.
> 
> Hope that gives some ideas…

WTF. Did you even read what the netbuf_next() function actually does ?

Sylvain

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