From b15207b8cf1a1930fe5eb076c08c6ddc92d9282d Mon Sep 17 00:00:00 2001 From: Victoria Dye Date: Mon, 8 Aug 2022 19:07:52 +0000 Subject: unpack-trees: unpack new trees as sparse directories If 'unpack_single_entry()' is unpacking a new directory tree (that is, one not already present in the index) into a sparse index, unpack the tree as a sparse directory rather than traversing its contents and unpacking each file individually. This helps keep the sparse index as collapsed as possible in cases such as 'git reset --hard' restoring a outside-of-cone directory removed with 'git rm -r --sparse'. Without this patch, 'unpack_single_entry()' will only unpack a directory into the index as a sparse directory (rather than traversing into it and unpacking its files one-by-one) if an entry with the same name already exists in the index. This patch allows sparse directory unpacking without a matching index entry when the following conditions are met: 1. the directory's path is outside the sparse cone, and 2. there are no children of the directory in the index If a directory meets these requirements (as determined by 'is_new_sparse_dir()'), 'unpack_single_entry()' unpacks the sparse directory index entry and propagates the decision back up to 'unpack_callback()' to prevent unnecessary tree traversal into the unpacked directory. Reported-by: Shaoxuan Yuan Signed-off-by: Victoria Dye Signed-off-by: Junio C Hamano --- unpack-trees.c | 106 +++++++++++++++++++++++++++++++++++++++++++++++++++------ 1 file changed, 96 insertions(+), 10 deletions(-) (limited to 'unpack-trees.c') diff --git a/unpack-trees.c b/unpack-trees.c index d561ca01ed..9ac7783e2e 100644 --- a/unpack-trees.c +++ b/unpack-trees.c @@ -1069,6 +1069,67 @@ static struct cache_entry *create_ce_entry(const struct traverse_info *info, return ce; } +/* + * Determine whether the path specified by 'p' should be unpacked as a new + * sparse directory in a sparse index. A new sparse directory 'A/': + * - must be outside the sparse cone. + * - must not already be in the index (i.e., no index entry with name 'A/' + * exists). + * - must not have any child entries in the index (i.e., no index entry + * 'A/' exists). + * If 'p' meets the above requirements, return 1; otherwise, return 0. + */ +static int entry_is_new_sparse_dir(const struct traverse_info *info, + const struct name_entry *p) +{ + int res, pos; + struct strbuf dirpath = STRBUF_INIT; + struct unpack_trees_options *o = info->data; + + if (!S_ISDIR(p->mode)) + return 0; + + /* + * If the path is inside the sparse cone, it can't be a sparse directory. + */ + strbuf_add(&dirpath, info->traverse_path, info->pathlen); + strbuf_add(&dirpath, p->path, p->pathlen); + strbuf_addch(&dirpath, '/'); + if (path_in_cone_mode_sparse_checkout(dirpath.buf, o->src_index)) { + res = 0; + goto cleanup; + } + + pos = index_name_pos_sparse(o->src_index, dirpath.buf, dirpath.len); + if (pos >= 0) { + /* Path is already in the index, not a new sparse dir */ + res = 0; + goto cleanup; + } + + /* Where would this sparse dir be inserted into the index? */ + pos = -pos - 1; + if (pos >= o->src_index->cache_nr) { + /* + * Sparse dir would be inserted at the end of the index, so we + * know it has no child entries. + */ + res = 1; + goto cleanup; + } + + /* + * If the dir has child entries in the index, the first would be at the + * position the sparse directory would be inserted. If the entry at this + * position is inside the dir, not a new sparse dir. + */ + res = strncmp(o->src_index->cache[pos]->name, dirpath.buf, dirpath.len); + +cleanup: + strbuf_release(&dirpath); + return res; +} + /* * Note that traverse_by_cache_tree() duplicates some logic in this function * without actually calling it. If you change the logic here you may need to @@ -1078,21 +1139,44 @@ static int unpack_single_entry(int n, unsigned long mask, unsigned long dirmask, struct cache_entry **src, const struct name_entry *names, - const struct traverse_info *info) + const struct traverse_info *info, + int *is_new_sparse_dir) { int i; struct unpack_trees_options *o = info->data; unsigned long conflicts = info->df_conflicts | dirmask; + const struct name_entry *p = names; - if (mask == dirmask && !src[0]) - return 0; + *is_new_sparse_dir = 0; + if (mask == dirmask && !src[0]) { + /* + * If we're not in a sparse index, we can't unpack a directory + * without recursing into it, so we return. + */ + if (!o->src_index->sparse_index) + return 0; + + /* Find first entry with a real name (we could use "mask" too) */ + while (!p->mode) + p++; + + /* + * If the directory is completely missing from the index but + * would otherwise be a sparse directory, we should unpack it. + * If not, we'll return and continue recursively traversing the + * tree. + */ + *is_new_sparse_dir = entry_is_new_sparse_dir(info, p); + if (!*is_new_sparse_dir) + return 0; + } /* - * When we have a sparse directory entry for src[0], - * then this isn't necessarily a directory-file conflict. + * When we are unpacking a sparse directory, then this isn't necessarily + * a directory-file conflict. */ - if (mask == dirmask && src[0] && - S_ISSPARSEDIR(src[0]->ce_mode)) + if (mask == dirmask && + (*is_new_sparse_dir || (src[0] && S_ISSPARSEDIR(src[0]->ce_mode)))) conflicts = 0; /* @@ -1352,7 +1436,7 @@ static int unpack_sparse_callback(int n, unsigned long mask, unsigned long dirma { struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, }; struct unpack_trees_options *o = info->data; - int ret; + int ret, is_new_sparse_dir; assert(o->merge); @@ -1376,7 +1460,7 @@ static int unpack_sparse_callback(int n, unsigned long mask, unsigned long dirma * "index" tree (i.e., names[0]) and adjust 'names', 'n', 'mask', and * 'dirmask' accordingly. */ - ret = unpack_single_entry(n - 1, mask >> 1, dirmask >> 1, src, names + 1, info); + ret = unpack_single_entry(n - 1, mask >> 1, dirmask >> 1, src, names + 1, info, &is_new_sparse_dir); if (src[0]) discard_cache_entry(src[0]); @@ -1394,6 +1478,7 @@ 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; + int is_new_sparse_dir; /* Find first entry with a real name (we could use "mask" too) */ while (!p->mode) @@ -1440,7 +1525,7 @@ static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, str } } - if (unpack_single_entry(n, mask, dirmask, src, names, info) < 0) + if (unpack_single_entry(n, mask, dirmask, src, names, info, &is_new_sparse_dir)) return -1; if (o->merge && src[0]) { @@ -1478,6 +1563,7 @@ static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, str } if (!is_sparse_directory_entry(src[0], names, info) && + !is_new_sparse_dir && traverse_trees_recursive(n, dirmask, mask & ~dirmask, names, info) < 0) { return -1; -- cgit v1.2.3