As I was writing this commit message, I changed the plan for how
to fix this. Originally, I was going to set size_multiple = 2 in
builtin/fetch.c, which is how the subject line was created. I forgot
to change that to something more like:
"commit-graph: prefer default size_mult when given zero"
On 1/2/2020 11:14 AM, Derrick Stolee via GitGitGadget wrote:
> From: Derrick Stolee <dstolee@xxxxxxxxxxxxx>
>
> In 50f26bd ("fetch: add fetch.writeCommitGraph config setting",
> 2019-09-02), the fetch builtin added the capability to write a
> commit-graph using the "--split" feature. This feature creates
> multiple commit-graph files, and those can merge based on a set
> of "split options" including a size multiple. The default size
> multiple is 2, which intends to provide a log_2 N depth of the
> commit-graph chain where N is the number of commits.
>
> However, I noticed during dogfooding that my commit-graph chains
> were becoming quite large when left only to builds by 'git fetch'.
> It turns out that in split_graph_merge_strategy(), we default the
> size_mult variable to 2 except we override it with the context's
> split_opts if they exist. In builtin/fetch.c, we create such a
> split_opts, but do not populate it with values.
>
> This problem is due to two failures:
>
> 1. It is unclear that we can add the flag COMMIT_GRAPH_WRITE_SPLIT
> with a NULL split_opts.
> 2. If we have a non-NULL split_opts, then we override the default
> values even if a zero value is given.
>
> Correct both of these issues. First, do not override size_mult when
> the options provide a zero value. Second, stop creating a split_opts
> in the fetch builtin.
This is a correct description of the actual patch.
Thanks,
-Stolee
