Re: [PATCH 2/5] reftable/stack: add function to check if optimization is required

> Justin Tobler <jltobler@gmail.com> writes:
> 
> >> +int reftable_stack_compaction_required(struct reftable_stack *st,
> >> +				       bool use_heuristics,
> >> +				       bool *required)
> >> +{
> >> +	struct segment seg;
> >> +	int err = 0;
> >> +
> >> +	if (st->merged->tables_len < 2) {
> >> +		*required = false;
> >> +		return 0;
> >> +	}
> >
> > Both `reftable_stack_auto_compact()` and `suggest_compaction_segement()`
> > already check if the stack has less than two tables. I wonder if we can
> > avoid having multiple of these checks by instead having a single one at
> > the start of `stack_segements_for_compaction()`?
> >
> 
> Well we can't for two reasons:
> 1. We want to perform this check independent of whether `use_heuristics`
>    is set or not.
> 2. Currently `stack_segements_for_compaction()` does one thing only,
>    which is stack the segments. I wouldn't want to introduce another
>    responsibility to it.

> >> +	if (!use_heuristics) {
> >> +		*required = true;
> >> +		return 0;
> >> +	}
> >
> > Is there a reason we would want to skip validating the geometric
> > sequence and just assume it compaction is required?
> >
> 
> This is the difference between running 'git refs optimize' with and
> without '--auto'. With '--auto' we will use heuristics to do a geometric
> progression. Without, we simply compact all tables into one.