On Thu, May 24 2018, Derrick Stolee wrote:

Thanks for all the feedback on v2. I've tried to make this round's
review a bit easier by splitting up the commits into smaller pieces.
Also, the test script now has less boilerplate and uses variables and
clear arithmetic to explain which bytes are being modified.

Thanks. it's a lot easier.

One other change worth mentioning: in "commit-graph: add '--reachable'
option" I put the ref-iteration into a new external
'write_commit_graph_reachable()' method inside commit-graph.c. This
makes the 'gc: automatically write commit-graph files' a simpler change.

Maybe you want this, maybe not, but I came up with this to squash:

    diff --git a/Documentation/config.txt b/Documentation/config.txt
    index 9a3abd87e7..2665522385 100644
    --- a/Documentation/config.txt
    +++ b/Documentation/config.txt
    @@ -900,7 +900,8 @@ the `GIT_NOTES_REF` environment variable.  See linkgit:git-notes[1].

     core.commitGraph::
            Enable git commit graph feature. Allows reading from the
    -       commit-graph file.
    +       commit-graph file. See `gc.commitGraph` for automatically
    +       maintaining the file.

     core.sparseCheckout::
            Enable "sparse checkout" feature. See section "Sparse checkout" in
    @@ -1554,10 +1555,10 @@ gc.autoDetach::
            if the system supports it. Default is true.

     gc.commitGraph::
    -       If true, then gc will rewrite the commit-graph file after any
    -       change to the object database. If '--auto' is used, then the
    -       commit-graph will not be updated unless the threshold is met.
    -       See linkgit:git-commit-graph[1] for details.
    +       If true, then gc will rewrite the commit-graph file when
    +       linkgit:git-gc[1] is run. When using linkgit:git-gc[1]
    +       '--auto' the commit-graph will be updated if housekeeping is
    +       required. See linkgit:git-commit-graph[1] for details.

     gc.logExpiry::
            If the file gc.log exists, then `git gc --auto` won't run

I.e. let's mention the new gc.commitGraph in core.commitGraph, and I
think the "any change to the object database" line in gc.commitGraph is
needlessly confusing, let's just say "when git-gc is run".