Re: Rmail changes for Emacs 22

[Kenichi Handa <handa@m17n.org>]

In article <E184Fgb-0007jf-00@fencepost.gnu.org>, Richard Stallman <rms@gnu.org> writes:
>     I said it should never *en*code.  Obviously, it will have to decode
>     somewhere on the way between the mbox file and the display.

> The question at hand is when and how to do the decoding.

I have not yet thought of it deeply, but it seems that we
have these options.

(1) A simple way:

Decode only when we need the contents of a message (e.g. for
displaying or searching).

This may be slow on searching all messages repeatedly.

Morioka-san's rmail-mime package is implemented by this way.
Actually, the current rmail code already contains necessary
code to implement it easily (see
rmail-XXX-mime-YYY-function).


(2) Another simple but memory consuming way:

Have a parallel decoded buffer that contains all messaages
decoded.

This may cause a memory shortage if RMAIL file is large,

(3) Not simple but efficient way:

Have a parallel decoded buffer but make it grow on demand.

(4) More efficient way:

Same as (3), but make rmail-backend not to keep the original
RMAIL file in a buffer.  It read the file once, scan it and
keep file positions of all messages, then kill the buffer.
Later, on request, rmail-backend reads portion of the RMAIL
file one by one.

---
Ken'ichi HANDA
handa@m17n.org