Re: Note on PushbackInputStream

[Bryce McKinlay]

Tom Tromey wrote:

> Suppose a thread calls PushbackInputStream.read and there are no bytes
> to be read.  So the thread blocks.
>
> Now suppose another thread calls PushbackInputStream.unread.
>
> Ideally you'd expect the first thread to wake up and read the
> pushed-back bytes.  However, this doesn't happen.  And in fact it
> isn't easy to make it happen.  I think you could do it by making a new
> thread inside PushbackInputStream.read.  That is awfully heavy though.
In general, I dont think its useful/safe to have more than one thread 
reading from any given InputStream, so in practise this probibly isnt a 
problem. Besides, even if there was a way to unblock another reading 
thread, there would still be consistency issues. If thread A reads a 
chunk of data, then thread B reads a chunk, then thread A decides to 
push back a byte, that byte would no longer be in the correct position 
on the stream.

regards

Bryce