Re: [PATCH 0/8] commit-graph: drop CHECK_OIDS, peel in callers

[Derrick Stolee <stolee@gmail.com>]

On 5/4/2020 9:13 PM, Taylor Blau wrote:
> Hi,
> 
> These are a few patches to address [1]

We seem to be missing links [1] and [2].

>   - It is often convenient to pipe the output of 'git for-each-ref' into
>     'git commit-graph write --stdin-commits', but handling multi-layer
>     tags is frustrating (at the very least, you have to peel them
>     yourself in 'for-each-ref', incurring a higher-than-necessary cost
>     outside of the commit-graph invocation)
> 
>   - It would be much more convenient if 'git commit-graph write
>     --stdin-commits' ignored OIDs that peel down to non-commit objects
>     silently, while still warning the caller about objects that (a)
>     don't exist, or (b) invalid hash inputs (for e.g., "HEAD", or
>     "refs/heads/foo").
> 
>   - By making this change, we are allowing *more* possible behaviors
>     than in previous versions, and the only case that we are breaking
>     (that 'git commit-graph write --stdin-commits' complains on
>     non-commit OIDs) can be addressed by peeling outside of
>     'commit-graph write' [2].

I agree that these are worthy goals. If someone was _depending_ on
the "git commit-graph write" command to _fail_, then they chose a
strange way to discover a ref that points to a non-commit.

> The first six patches move peeling refs out from the commit-graph
> internals, and into the callers.
> 
> This has no impact on the '--stdin-commits' case, but is a potential
> improvement for '--reachable', where it is more efficient to call
> 'peel_ref()' than 'lookup_commit_reference_gently()'. There is an
> intermediate state (that is resolved in the final patch) where we can
> have more than one progress meter (since the progress meter moved with
> the perhaps-expensive operations out of the commit-graph internals,
> too), but the final patch addresses this.

Interesting. I'll be sure to look carefully at this progress handling
as this has potential to lose our progress options. I expect that you
were careful about this.

> The last two patches lift the restriction on input to '--stdin-commits'
> resolving to commit objects, instead making the behavior to silently
> drop non-commit OIDs, and continue complain about invalid OIDs, and
> valid-but-missing OIDs.
> 
> Finally, this topic isn't based on anything that isn't already in
> 'master', so I think the days of many tangle commit-graph topics are
> behind us.

Woo!

-Stolee