[PATCH v2 5/5] rebase: use 'skip_cache_tree_update' option

From: Victoria Dye via GitGitGadget <gitgitgadget@gmail.com>
Date: Nov 10, 2022, 01:57 UTC
Message-ID: <fffe2fc17ed3beb05376f1377ea193199c13c657.1668045438.git.gitgitgadget@gmail.com>
In-Reply-To: <pull.1411.v2.git.1668045438.gitgitgadget@gmail.com>

From: Victoria Dye <vdye@github.com>

Enable the 'skip_cache_tree_update' option in both 'do_reset()' ('sequencer.c') and 'reset_head()' ('reset.c'). Both of these callers invoke 'prime_cache_tree()' after 'unpack_trees()', so we can remove an unnecessary cache tree rebuild by skipping 'cache_tree_update()'.

When testing with 'p3400-rebase.sh' and 'p3404-rebase-interactive.sh', the performance change of this update was negligible, likely due to the operation being dominated by more expensive operations (like checking out trees). However, since the change doesn't harm performance, it's worth keeping this 'unpack_trees()' usage consistent with others that subsequently invoke 'prime_cache_tree()'.

Signed-off-by: Victoria Dye <vdye@github.com>
---
 reset.c     | 1 +
 sequencer.c | 1 +
 2 files changed, 2 insertions(+)

diff --git a/reset.c b/reset.c
index e3383a93343..5ded23611f3 100644
--- a/reset.c
+++ b/reset.c
@@ -128,6 +128,7 @@ int reset_head(struct repository *r, const struct reset_head_opts *opts)
 	unpack_tree_opts.update = 1;
 	unpack_tree_opts.merge = 1;
 	unpack_tree_opts.preserve_ignored = 0; /* FIXME: !overwrite_ignore */
+	unpack_tree_opts.skip_cache_tree_update = 1;
 	init_checkout_metadata(&unpack_tree_opts.meta, switch_to_branch, oid, NULL);
 	if (reset_hard)
 		unpack_tree_opts.reset = UNPACK_RESET_PROTECT_UNTRACKED;
diff --git a/sequencer.c b/sequencer.c
index e658df7e8ff..3f7a73ce4e1 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -3750,6 +3750,7 @@ static int do_reset(struct repository *r,
 	unpack_tree_opts.merge = 1;
 	unpack_tree_opts.update = 1;
 	unpack_tree_opts.preserve_ignored = 0; /* FIXME: !overwrite_ignore */
+	unpack_tree_opts.skip_cache_tree_update = 1;
 	init_checkout_metadata(&unpack_tree_opts.meta, name, &oid, NULL);
 
 	if (repo_read_index_unmerged(r)) {

-- 
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