Re: [PATCH v2 08/17] merge-ort: implement handle_directory_level_conflicts()

On Thu, Jan 07, 2021 at 09:35:56PM +0000, Elijah Newren via GitGitGadget wrote:

From: Elijah Newren <redacted>

This is modelled on the version of handle_directory_level_conflicts()
from merge-recursive.c, but is massively simplified due to the following
factors:
  * strmap API provides simplifications over using direct hashamp
  * we have a dirs_removed field in struct rename_info that we have an
    easy way to populate from collect_merge_info(); this was already
    used in compute_rename_counts() and thus we do not need to check
    for condition #2.
  * The removal of condition #2 by handling it earlier in the code also
    obviates the need to check for condition #3 -- if both sides renamed
    a directory, meaning that the directory no longer exists on either
    side, then neither side could have added any new files to that
    directory, and thus there are no files whose locations we need to
    move due to such a directory rename.

In fact, the same logic that makes condition #3 irrelevant means
condition #1 is also irrelevant so we could drop this function.
However, it is cheap to check if both sides rename the same directory,
and doing so can save future computation.  So, simply remove any
directories that both sides renamed from the list of directory renames.

Beautiful.

 static void handle_directory_level_conflicts(struct merge_options *opt)
 {
-	die("Not yet implemented!");
+	struct hashmap_iter iter;
+	struct strmap_entry *entry;
+	struct string_list duplicated = STRING_LIST_INIT_NODUP;
+	struct strmap *side1_dir_renames = &opt->priv->renames.dir_renames[1];
+	struct strmap *side2_dir_renames = &opt->priv->renames.dir_renames[2];

Obviously saying "1" or "MERGE_SIDE1" are two ways of saying the same
thing, but perhaps the latter is more easily grep-able? Dunno.

+	int i;
+
+	strmap_for_each_entry(side1_dir_renames, &iter, entry) {
+		if (strmap_contains(side2_dir_renames, entry->key))
+			string_list_append(&duplicated, entry->key);
+	}
+
+	for (i=0; i<duplicated.nr; ++i) {

One small nit: this spacing and prefixed ++ reads a little oddly to me.
Perhaps:

  for (i = 0; i < duplicated.nr; i++) {

?

+		strmap_remove(side1_dir_renames, duplicated.items[i].string, 0);
+		strmap_remove(side2_dir_renames, duplicated.items[i].string, 0);
+	}
+	string_list_clear(&duplicated, 0);

And this looks like a faithful implementation of what you described
above. Thanks.

Thanks,
Taylor