Thingbuf Peek / view front

[micahcc]

I'm writing a socket writer where I won't know how many bytes are consumed until after I've viewed the data.

I have roughly the following:

struct InFlight {
   pos: usize,
   data: Vec<u8>,
}

fn foo() -> Result<()> {
    let buf = Thingbuf<InFlight>::new(10);
   // feed the buf

  loop {
    let next = buf.front_mut(); // this function doesn't exist but I need it
    let sent_bytes = send(next.data[pos..])?;
    next.pos += sent_bytes;

    if next.pos == next.data.len() {
      buf.pop_front();
   }
  }
}

The key here is if I preemptively pop_front() I might not have consumed all the bytes in InFlight yet