Re: STREAM:STREAM-FILL-BUFFER

On Thu, 27 Nov 2003 14:08:43 GMT, davef@xanalys.com wrote:

> You can use WITH-STREAM-INPUT-BUFFER (example below) and check the
> LIMIT and INDEX. Note that these values represent character units,
> not bytes (octets), although for BASE-CHAR SOCKET-STREAMs this will
> be the same thing.
>
> I don't know how you're getting the buffer state

  (slot-value stream 'stream::buffer-state)

> or why you think the difference between LIMIT and INDEX is not the
> right thing.

As I said, I was trying to fix a bug in the chunked encoding
implementation of Portable AllegroServe. I didn't know the code before
and just tried to get it to work for me. I found out about the buffer
state with LW's introspection tools but then realized that
WITH-STREAM-INPUT-BUFFER (which is used in the Portable AllegroServe
code) did what I need. So I gave it a try and failed. It turns out
that this was because of the caching you mention below which didn't
occur to me. (As I said: No docs, so I was just guessing and playing
around.)

> Be aware that WITH-STREAM-INPUT-BUFFER caches the value, so the form
> must be reentered after other stream functions such as
> STREAM-FILL-BUFFER have been called. Typically that means you need a
> loop like this:
>
> (loop (stream:with-stream-input-buffer (buffer index limit) stream
>         (if (> limit index) ; buffer contains something
>             (multiple-value-bind (new-index finished)
>                 (consume-some-of-the-buffer buffer index limit)
>               (setf index new-index)
>               (when finished
>                 (return)))
>           (unless (stream:stream-fill-buffer stream)
> 	    (end-of-file-before-work-finished)))))

Thanks for your help. Rudi Schlatte has since fixed the bug but I've
forwarded your advice to the Portable AllegroServe maintainers hoping
that it might be helpful.

Thanks again,
Edi.