Re: [PATCH 3/5] repo-settings: parse core.untrackedCache

From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: Jul 23, 2019, 15:04 UTC
Message-ID: <nycvar.QRO.7.76.6.1907231656580.21907@tvgsbejvaqbjf.bet>
In-Reply-To: <47ae3e7d4d765a00d14e8892db88a8936d56591b.1563818059.git.gitgitgadget@gmail.com>

Hi Stolee,

On Mon, 22 Jul 2019, Derrick Stolee via GitGitGadget wrote:

Show 20 quoted lines

> From: Derrick Stolee <dstolee@microsoft.com>
>
> The core.untrackedCache config setting is slightly complicated,
> so clarify its use and centralize its parsing into the repo
> settings.
>
> The default value is "keep" (returned as -1), which persists the
> untracked cache if it exists.
>
> If the value is set as "false" (returned as 0), then remove the
> untracked cache if it exists.
>
> If the value is set as "true" (returned as 1), then write the
> untracked cache and persist it.
>
> Instead of relying on magic values of -1, 0, and 1, split these
> options into bitflags CORE_UNTRACKED_CACHE_KEEP and
> CORE_UNTRACKED_CACHE_WRITE. This allows the use of "-1" as a
> default value. After parsing the config options, if the value is
> unset we can initialize it to CORE_UNTRACKED_CACHE_KEEP.

Nice!

Show 30 quoted lines

> [...]
> diff --git a/read-cache.c b/read-cache.c
> index ee1aaa8917..e67e6f6e3e 100644
> --- a/read-cache.c
> +++ b/read-cache.c
> @@ -1846,18 +1846,17 @@ static void check_ce_order(struct index_state *istate)
>
>  static void tweak_untracked_cache(struct index_state *istate)
>  {
> -	switch (git_config_get_untracked_cache()) {
> -	case -1: /* keep: do nothing */
> -		break;
> -	case 0: /* false */
> +	struct repository *r = the_repository;
> +
> +	prepare_repo_settings(r);
> +
> +	if (!(r->settings->core_untracked_cache & CORE_UNTRACKED_CACHE_KEEP)) {
>  		remove_untracked_cache(istate);
> -		break;
> -	case 1: /* true */
> -		add_untracked_cache(istate);
> -		break;
> -	default: /* unknown value: do nothing */
> -		break;
> +		return;
>  	}
> +
> +	if (r->settings->core_untracked_cache & CORE_UNTRACKED_CACHE_WRITE)
> +		add_untracked_cache(istate);

This changes the flow in a subtle way: in the `CORE_UNTRACKED_CACHE_WRITE` case, we used to _not_ remove the untracked cache, but now we do.

I _think_ what you would want to do is replace the `!(..._KEEP)` condition by `..._REMOVE`.

Show 33 quoted lines

>  }
>
>  static void tweak_split_index(struct index_state *istate)
> diff --git a/repo-settings.c b/repo-settings.c
> index f328602fd7..807c5a29d6 100644
> --- a/repo-settings.c
> +++ b/repo-settings.c
> @@ -30,6 +30,20 @@ static int git_repo_config(const char *key, const char *value, void *cb)
>  		rs->index_version = git_config_int(key, value);
>  		return 0;
>  	}
> +	if (!strcmp(key, "core.untrackedcache")) {
> +		int bool_value = git_parse_maybe_bool(value);
> +		if (bool_value == 0)
> +			rs->core_untracked_cache = 0;
> +		else if (bool_value == 1)
> +			rs->core_untracked_cache = CORE_UNTRACKED_CACHE_KEEP |
> +						   CORE_UNTRACKED_CACHE_WRITE;
> +		else if (!strcasecmp(value, "keep"))
> +			rs->core_untracked_cache = CORE_UNTRACKED_CACHE_KEEP;
> +		else
> +			error(_("unknown core.untrackedCache value '%s'; "
> +				"using 'keep' default value"), value);
> +		return 0;
> +	}
>
>  	return 1;
>  }
> @@ -46,6 +60,13 @@ void prepare_repo_settings(struct repository *r)
>  	r->settings->gc_write_commit_graph = -1;
>  	r->settings->pack_use_sparse = -1;
>  	r->settings->index_version = -1;
> +	r->settings->core_untracked_cache = -1;

At this point at the latest, I am starting to wonder whether it would not make more sense to use `memset(..., -1, sizeof(struct repo_settings)` instead.

Show 19 quoted lines

>
>  	repo_config(r, git_repo_config, r->settings);
> +
> +	/* Hack for test programs like test-dump-untracked-cache */
> +	if (ignore_untracked_cache_config)
> +		r->settings->core_untracked_cache = CORE_UNTRACKED_CACHE_KEEP;
> +	else
> +		UPDATE_DEFAULT(r->settings->core_untracked_cache, CORE_UNTRACKED_CACHE_KEEP);
>  }
> diff --git a/repo-settings.h b/repo-settings.h
> index 1151c2193a..bac9b87d49 100644
> --- a/repo-settings.h
> +++ b/repo-settings.h
> @@ -1,11 +1,15 @@
>  #ifndef REPO_SETTINGS_H
>  #define REPO_SETTINGS_H
>
> +#define CORE_UNTRACKED_CACHE_WRITE (1 << 0)
> +#define CORE_UNTRACKED_CACHE_KEEP (1 << 1)

I think it would read even nicer as an enum. In any case, using `1<<1` suggests that this is a bit field, but I don't think that is what we actually want here. Instead, what `core_untracked_cache` seems to be (at least from my point of view) is a mode, where any two modes are mutually exclusive.

For example, what is the difference between `(_KEEP | _WRITE)` and `(_WRITE)` supposed to be? That the latter writes a fresh untracked cache without looking at the previous one? That's not how the existing code behaves, though...

Ciao, Dscho

Show 14 quoted lines

> +
>  struct repo_settings {
>  	int core_commit_graph;
>  	int gc_write_commit_graph;
>  	int pack_use_sparse;
>  	int index_version;
> +	int core_untracked_cache;
>  };
>
>  struct repository;
> --
> gitgitgadget
>
>