…oder::decode caused by non-standard behavior of shmipc sdk if a connection is closed normally

Motivation

Fix an unexpected UnexpectedEof log in volo-thrift/src/transport/pingpong/server.rs in ShmIPC mode if a ShmIPC connection is closed nomarlly.

The error return chain looks like:

shmipc::Stream::read()
    → read_more() // Return Error::EndOfStream
        → shmipc::compact::StreamExt::poll_read() // e.into() converts to io::Error(UnexpectedEof)
            → volo::BufReader::poll_fill_buf()
                → fill_buf().await? throw UnexpectedEof

Solution

If we can not read even a single byte at the very beginning of DefaultDecoder::decode in ShmIPC mode, which means we will catch a UnexpectedEof Err, it can be regarded as a normal connection close and just return Ok(None) to let volo to do some clean.