Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!pasteur!ames!lll-winken!uunet!mcvax!ukc!dcl-cs!aber-cs!pcg
From: pcg@aber-cs.UUCP (Piercarlo Grandi)
Newsgroups: comp.mail.elm
Subject: A small change to ELM memory allocation...
Summary: Please, for the sake of segmented machines!
Message-ID: <772@aber-cs.UUCP>
Date: 15 Mar 89 14:11:12 GMT
Reply-To: pcg@cs.aber.ac.uk (Piercarlo Grandi)
Distribution: eunet,world
Organization: Dept of CS, UCW Aberystwyth
	(Disclaimer: my statements are purely personal)
Lines: 32

In Elm 1.7 there is a table of all headers in the mailbox, called
"header_table", that is realloc'ed to increase its size whenever
the number of headers increases.

It would help a lot, and impact performance minimally, or actually
probably increse it, to allocate a table of POINTERS to
headers, even with a pretty large initial size, and then allocate the
headers one by one within it.

This would have TWO large advantages for poor 286 like machines:

*   It does not require all the headers to be contiguous, therefore
    it becomes possible to allocate more than a segment worth of headers
    for mailboxes with many messages.

*   It avoid realloc'ing a potentially large table, that most probably
    requires a new larger one to be allocated, the old one to copied
    into it, and the old one freed, and most likely not used any more.

It also the obvious advantage of helping with sorting speed, because only
pointers would have to be arranged.

I am doing a quick'n dirty fix to 1.7 to implement this, and it is fairly
easy. Please do the same more elegantly to Elm 2.2...  I would vote for
having a fixed size pointer table, with a configurable size, or to allocate
it once with malloc with either a default size or one read from the
environemtn or the command line. I do not think that realloc'ing such a
table would buy much.
-- 
Piercarlo "Peter" Grandi            |  ARPA: pcg%cs.aber.ac.uk@nss.cs.ucl.ac.uk
Dept of CS, UCW Aberystwyth         |  UUCP: ...!mcvax!ukc!aber-cs!pcg
Penglais, Aberystwyth SY23 3BZ, UK  |  INET: pcg@cs.aber.ac.uk