pipes::peek returns true unexpectedly

[brson]

extern mod std;
use core::pipes::*;
use std::comm::DuplexStream;
use core::task;

fn main () {
    let (chan, port): (Chan<int>, Port<int>) = stream();

    do task::spawn() |move port| {
        assert port.recv() == 123;
        assert !port.peek();
    }

    chan.send(123);
}

There is no message available but peek returns true, likely because this: https://github.com/mozilla/rust/blob/incoming/src/libcore/pipes.rs#L516

I expect that anytime peek returns true I can call recv successfully.

[eholk]

Wow, I should pay more attention to these threads :)

The original behavior (closed pipes return true) was intentional on my part. The rational is that peek returns true when something has happened on the pipe that you might care about. For example, if we had a loop that kept using peek to test for a message, we'd want to know if the pipe closed so we could terminate the loop.

That said, I can see the argument for the new behavior, so I'm fine if people would rather it be the other way. Perhaps we could have peek that returns an enum of MessageWaiting, Terminated or NoData.