Re: [PATCH v4 4/4] cache-tree: Write updated cache-tree after commit

Duy Nguyen [off-list ref] writes:

Writing cache tree early in prepare_index() does help hooks, but I
would say hooks are uncommon case and we could add an option to
update-index to explicitly rebuild cache-tree, then hooks that do diff
a lot (or other operations that use cache-tree) could rebuild
cache-tree by themselves.

Yes, "update-index --update-cache-tree" would be a good addition for
completeness; scripts working with plumbing should be able to do
what built-in Porcelains can.  They can of course do "write-tree" in
the meantime so I do not see it as a very high priority, though.

This should apply on top of 'master', and if the series under
discussion turns out to be a good idea, the new call to
update-main-cache-tree I added to this code path should use the
option added by the series that only repairs parts of cache-trees
that can be repaird without writing out new trees, so it is just to
give hints to future people (iow I am not going to apply this patch
myself right now).

 builtin/update-index.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/builtin/update-index.c b/builtin/update-index.c
index ebea285..1ce2274 100644
--- a/builtin/update-index.c
+++ b/builtin/update-index.c

@@ -26,6 +26,7 @@ static int allow_remove;
 static int allow_replace;
 static int info_only;
 static int force_remove;
+static int update_cache_tree;
 static int verbose;
 static int mark_valid_only;
 static int mark_skip_worktree_only;

@@ -762,6 +763,8 @@ int cmd_update_index(int argc, const char **argv, const char *prefix)
 		OPT_BIT(0, "unmerged", &refresh_args.flags,
 			N_("refresh even if index contains unmerged entries"),
 			REFRESH_UNMERGED),
+		OPT_BOOL(0, "update-cache-tree", &update_cache_tree,
+			 N_("update cache-tree before writing the result out")),
 		{OPTION_CALLBACK, 0, "refresh", &refresh_args, NULL,
 			N_("refresh stat information"),
 			PARSE_OPT_NOARG | PARSE_OPT_NONEG,

@@ -918,6 +921,11 @@ int cmd_update_index(int argc, const char **argv, const char *prefix)
 		strbuf_release(&buf);
 	}
 
+	if (update_cache_tree && !unmerged_cache()) {
+		update_main_cache_tree(0);
+		active_cache_changed = 1; /* force write-out */
+	}
+
 	if (active_cache_changed) {
 		if (newfd < 0) {
 			if (refresh_args.flags & REFRESH_QUIET)