Interactions between history library & innconf

[Alex Kiernan]

I've got two dependencies on innconf in the history stuff, one for the
type of history you want ("hismethod") and one for sync interval
("icdsynccount").

Having the hismethod one inside the API means you can't open two
different history implementations at the same time, which feels wrong
- not least to do a convert you have to implement that in the library,
rather than as an external iterator + writer. I'm inclined to make the
hismethod setting a parameter passed into HISopen so that you can
control this from the caller directly.

The icdsynccount is harder, since its a significant change in the
caller, The only place where its relevant is in innd, and thats
already doing that check (in ARTpost), moving it there doesn't seem
like a significant hardship. Alternatively I could pass that interval
in through HISopen, or add a HISsetopt type interface. To be honest
making the caller do HISsync feels like adding library policy to the
caller & I really don't like that.

Actually now I've though of HISsetopt, I'm inclined to go that way,
but I'm mindful of Russ' comments elsewhere on the number of calls to
get your API going...

Opinions?

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