diff options
author | Victoria Dye <vdye@github.com> | 2022-03-01 23:24:30 +0300 |
---|---|---|
committer | Junio C Hamano <gitster@pobox.com> | 2022-03-01 23:36:01 +0300 |
commit | ab81047a6c5c4f98640f8a2f56e138367cfdada9 (patch) | |
tree | 5d2038e540475bf75cccbf97ef7526f0a3975f4a /unpack-trees.c | |
parent | 749703924121b9eb2750b4313b2c769113c8b310 (diff) |
read-tree: make two-way merge sparse-aware
Enable two-way merge with 'git read-tree' without expanding the sparse
index. When in a sparse index, a two-way merge will trivially succeed as
long as there are not changes to the same sparse directory in multiple trees
(i.e., sparse directory-level "edit-edit" conflicts). If there are such
conflicts, the merge will fail despite the possibility that individual files
could merge cleanly.
In order to resolve these "edit-edit" conflicts, "conflicted" sparse
directories are - rather than rejected - merged by traversing their
associated trees by OID. For each child of the sparse directory:
1. Files are merged as normal (see Documentation/git-read-tree.txt for
details).
2. Subdirectories are treated as sparse directories and merged in
'twoway_merge'. If there are no conflicts, they are merged according to
the rules in Documentation/git-read-tree.txt; otherwise, the subdirectory
is recursively traversed and merged.
This process allows sparse directories to be individually merged at the
necessary depth *without* expanding a full index.
The 't/t1092-sparse-checkout-compatibility.sh' test 'read-tree --merge with
edit/edit conflicts in sparse directories' tests two-way merges with 1)
changes inside sparse directories that do not conflict and 2) changes that
do conflict (with the correct file(s) reported in the error message).
Additionally, add two-way merge cases to 'sparse index is not expanded:
read-tree' to confirm that the index is not expanded regardless of whether
edit/edit conflicts are present in a sparse directory.
Signed-off-by: Victoria Dye <vdye@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'unpack-trees.c')
-rw-r--r-- | unpack-trees.c | 75 |
1 files changed, 75 insertions, 0 deletions
diff --git a/unpack-trees.c b/unpack-trees.c index f3667d85ec..0c2a678cd6 100644 --- a/unpack-trees.c +++ b/unpack-trees.c @@ -1360,6 +1360,42 @@ static int is_sparse_directory_entry(struct cache_entry *ce, return sparse_dir_matches_path(ce, info, name); } +static int unpack_sparse_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry *names, struct traverse_info *info) +{ + struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, }; + struct unpack_trees_options *o = info->data; + int ret; + + assert(o->merge); + + /* + * Unlike in 'unpack_callback', where src[0] is derived from the index when + * merging, src[0] is a transient cache entry derived from the first tree + * provided. Create the temporary entry as if it came from a non-sparse index. + */ + if (!is_null_oid(&names[0].oid)) { + src[0] = create_ce_entry(info, &names[0], 0, + &o->result, 1, + dirmask & (1ul << 0)); + src[0]->ce_flags |= (CE_SKIP_WORKTREE | CE_NEW_SKIP_WORKTREE); + } + + /* + * 'unpack_single_entry' assumes that src[0] is derived directly from + * the index, rather than from an entry in 'names'. This is *not* true when + * merging a sparse directory, in which case names[0] is the "index" source + * entry. To match the expectations of 'unpack_single_entry', shift past the + * "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); + + if (src[0]) + discard_cache_entry(src[0]); + + return ret >= 0 ? mask : -1; +} + /* * 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 @@ -2472,6 +2508,37 @@ static int merged_entry(const struct cache_entry *ce, return 1; } +static int merged_sparse_dir(const struct cache_entry * const *src, int n, + struct unpack_trees_options *o) +{ + struct tree_desc t[MAX_UNPACK_TREES + 1]; + void * tree_bufs[MAX_UNPACK_TREES + 1]; + struct traverse_info info; + int i, ret; + + /* + * Create the tree traversal information for traversing into *only* the + * sparse directory. + */ + setup_traverse_info(&info, src[0]->name); + info.fn = unpack_sparse_callback; + info.data = o; + info.show_all_errors = o->show_all_errors; + info.pathspec = o->pathspec; + + /* Get the tree descriptors of the sparse directory in each of the merging trees */ + for (i = 0; i < n; i++) + tree_bufs[i] = fill_tree_descriptor(o->src_index->repo, &t[i], + src[i] && !is_null_oid(&src[i]->oid) ? &src[i]->oid : NULL); + + ret = traverse_trees(o->src_index, n, t, &info); + + for (i = 0; i < n; i++) + free(tree_bufs[i]); + + return ret; +} + static int deleted_entry(const struct cache_entry *ce, const struct cache_entry *old, struct unpack_trees_options *o) @@ -2742,6 +2809,14 @@ int twoway_merge(const struct cache_entry * const *src, * reject the merge instead. */ return merged_entry(newtree, current, o); + } else if (S_ISSPARSEDIR(current->ce_mode)) { + /* + * The sparse directories differ, but we don't know whether that's + * because of two different files in the directory being modified + * (can be trivially merged) or if there is a real file conflict. + * Merge the sparse directory by OID to compare file-by-file. + */ + return merged_sparse_dir(src, 3, o); } else return reject_merge(current, o); } |