Assorted history questions

[Alex Kiernan]

After pulling & pushing the history API idea into -current, I'm left
with a bunch of odds & ends which I'd like thoughts on:

grephistory can't support -h or -t (offset & hash aren't exposed by
the API), also you can't search by hash any more; these don't look
like very serious restrictions.

prunehistory looks like it can be done with HISreplace (which I
haven't implemented yet), but does anyone actually use prunehistory
(actually I guess the answer is, if its there someone will have found
a use for it in the past).

expire can't support -d (specify new directory), -f (specify new
history base name), -i (ignore old database) or -x (don't write); most
of these (with the exception of -f ?) look like they are needed.

makehistory when running without -x creates the history and the
associated dbz files; it could do with some extra dbz specific flags
in the HISopen though (like telling it to create the dbz in core).

nnrpd's checking of the current history file now appears in HISlookup,
but every application gets this (right now it just stats the history
file at no less than 30s intervals, that bit needs to be
configurable), but should their be some way of defeating this for innd
(and expire, grephistory etc.), should it be explicitly enabled instead?

How was `threshold' to HISexpire expected to work - I'm assuming upper
bound on the arrival time for articles passed to the callback; if you
tell expire to do decisions based on posting time you need to pass in
"infinite" (which I guess probably means 0 as a special case).

Need to think of a design for replacing initial database creation (or
should it just do like ovdb & create the files it needs, sizing a
problem then though I guess).

-- 
Alex Kiernan, Principal Engineer, Development, Thus PLC