How does zero copy work when receiving data from socket and pushing it to a file?

[Alan Bateman]

On 20/10/2020 14:16, kant kodali wrote:
> :
>
> so seems to me that
>
> reading data from local file -> do some verification on data -> send 
> it to socket (Zero copy possible)
>
> reading data from socket -> do some verification on data -> send it to 
> local file (Zero copy not possible)
>
> is that correct?
>
Yes, that's a fair summary. The transferTo method is implemented to use 
sendfile if possible. Nothing equivalent in the transferFrom 
implementation so socket -> file will always go through intermediate 
buffers.

-Alan.