Re: [PATCH 16/27] unpack-trees: make sparse aware

>
> From: Derrick Stolee <dstolee@microsoft.com>
>
> As a first step to integrate 'git status' and 'git add' with the sparse
> index, we must start integrating unpack_trees() with sparse directory
> entries. These changes are currently impossible to trigger because
> unpack_trees() calls ensure_full_index() if command_requires_full_index
> is true. This is the case for all commands at the moment. As we expand
> more commands to be sparse-aware, we might find that more changes are
> required to unpack_trees(). The current changes will suffice for
> 'status' and 'add'.
>
> unpack_trees() calls the traverse_trees() API using unpack_callback()
> to decide if we should recurse into a subtree. We must add new abilities
> to skip a subtree if it corresponds to a sparse directory entry.

> Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
> ---
>  dir.h           |  2 +-
>  preload-index.c |  2 ++
>  read-cache.c    |  3 +++
>  unpack-trees.c  | 24 ++++++++++++++++++++++--
>  4 files changed, 28 insertions(+), 3 deletions(-)
>
> diff --git a/dir.h b/dir.h
> index facfae47402..300305ec335 100644
> --- a/dir.h
> +++ b/dir.h
> @@ -503,7 +503,7 @@ static inline int ce_path_match(const struct index_state *istate,
>                                 char *seen)
>  {
>         return match_pathspec(istate, pathspec, ce->name, ce_namelen(ce), 0, seen,
> -                             S_ISDIR(ce->ce_mode) || S_ISGITLINK(ce->ce_mode));
> +                             S_ISSPARSEDIR(ce) || S_ISDIR(ce->ce_mode) || S_ISGITLINK(ce->ce_mode));

>  }
>
>  static inline int dir_path_match(const struct index_state *istate,
> diff --git a/preload-index.c b/preload-index.c
> index ed6eaa47388..323fc8c5100 100644
> --- a/preload-index.c
> +++ b/preload-index.c
> @@ -54,6 +54,8 @@ static void *preload_thread(void *_data)
>                         continue;
>                 if (S_ISGITLINK(ce->ce_mode))
>                         continue;
> +               if (S_ISSPARSEDIR(ce))
> +                       continue;
>                 if (ce_uptodate(ce))
>                         continue;
>                 if (ce_skip_worktree(ce))
> diff --git a/read-cache.c b/read-cache.c
> index 65679d70d7c..ab0c2b86ec0 100644
> --- a/read-cache.c
> +++ b/read-cache.c
> @@ -1572,6 +1572,9 @@ int refresh_index(struct index_state *istate, unsigned int flags,
>                 if (ignore_submodules && S_ISGITLINK(ce->ce_mode))
>                         continue;
>
> +               if (istate->sparse_index && S_ISSPARSEDIR(ce))
> +                       continue;
> +
>                 if (pathspec && !ce_path_match(istate, ce, pathspec, seen))
>                         filtered = 1;
>
> diff --git a/unpack-trees.c b/unpack-trees.c
> index b324eec2a5d..90644856a80 100644
> --- a/unpack-trees.c
> +++ b/unpack-trees.c
> @@ -583,6 +583,13 @@ static void mark_ce_used(struct cache_entry *ce, struct unpack_trees_options *o)
>  {
>         ce->ce_flags |= CE_UNPACKED;
>
> +       /*
> +        * If this is a sparse directory, don't advance cache_bottom.
> +        * That will be advanced later using the cache-tree data.
> +        */
> +       if (S_ISSPARSEDIR(ce))
> +               return;

> +
>         if (o->cache_bottom < o->src_index->cache_nr &&
>             o->src_index->cache[o->cache_bottom] == ce) {
>                 int bottom = o->cache_bottom;
> @@ -980,6 +987,9 @@ static int do_compare_entry(const struct cache_entry *ce,
>         ce_len -= pathlen;
>         ce_name = ce->name + pathlen;
>
> +       /* remove directory separator if a sparse directory entry */
> +       if (S_ISSPARSEDIR(ce))
> +               ce_len--;

>         return df_name_compare(ce_name, ce_len, S_IFREG, name, namelen, mode);
>  }
>
> @@ -989,6 +999,10 @@ static int compare_entry(const struct cache_entry *ce, const struct traverse_inf
>         if (cmp)
>                 return cmp;
>
> +       /* If ce is a sparse directory, then allow equality here. */
> +       if (S_ISSPARSEDIR(ce))
> +               return 0;
> +

>         /*
>          * Even if the beginning compared identically, the ce should
>          * compare as bigger than a directory leading up to it!
> @@ -1239,6 +1253,7 @@ static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, str
>         struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
>         struct unpack_trees_options *o = info->data;
>         const struct name_entry *p = names;
> +       unsigned recurse = 1;
>
>         /* Find first entry with a real name (we could use "mask" too) */
>         while (!p->mode)
> @@ -1280,12 +1295,16 @@ static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, str
>                                         }
>                                 }
>                                 src[0] = ce;
> +
> +                               if (S_ISSPARSEDIR(ce))
> +                                       recurse = 0;
>                         }
>                         break;
>                 }
>         }
>
> -       if (unpack_nondirectories(n, mask, dirmask, src, names, info) < 0)
> +       if (recurse &&
> +           unpack_nondirectories(n, mask, dirmask, src, names, info) < 0)
>                 return -1;
>
>         if (o->merge && src[0]) {
> @@ -1315,7 +1334,8 @@ static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, str
>                         }
>                 }
>
> -               if (traverse_trees_recursive(n, dirmask, mask & ~dirmask,
> +               if (recurse &&
> +                   traverse_trees_recursive(n, dirmask, mask & ~dirmask,
>                                              names, info) < 0)
>                         return -1;
>                 return mask;