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From: Elijah Newren <newren@gmail.com>
To: git@vger.kernel.org
Cc: Elijah Newren <newren@gmail.com>
Subject: [PATCH 07/20] merge-ort: avoid repeating fill_tree_descriptor() on the same tree
Date: Thu, 29 Oct 2020 20:41:18 -0700	[thread overview]
Message-ID: <20201030034131.1479968-8-newren@gmail.com> (raw)
In-Reply-To: <20201030034131.1479968-1-newren@gmail.com>

Three-way merges, by their nature, are going to often have two or more
trees match at a given subdirectory.  We can avoid calling
fill_tree_descriptor() on the same tree by checking when these trees
match.  Noting when various oids match will also be useful in other
calculations and optimizations as well.

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 merge-ort.c | 26 ++++++++++++++++++++++----
 1 file changed, 22 insertions(+), 4 deletions(-)

diff --git a/merge-ort.c b/merge-ort.c
index d652f1f062..7083388a47 100644
--- a/merge-ort.c
+++ b/merge-ort.c
@@ -99,6 +99,15 @@ static int collect_merge_info_callback(int n,
 	unsigned mbase_null = !(mask & 1);
 	unsigned side1_null = !(mask & 2);
 	unsigned side2_null = !(mask & 4);
+	unsigned side1_matches_mbase = (!side1_null && !mbase_null &&
+					names[0].mode == names[1].mode &&
+					oideq(&names[0].oid, &names[1].oid));
+	unsigned side2_matches_mbase = (!side2_null && !mbase_null &&
+					names[0].mode == names[2].mode &&
+					oideq(&names[0].oid, &names[2].oid));
+	unsigned sides_match = (!side1_null && !side2_null &&
+				names[1].mode == names[2].mode &&
+				oideq(&names[1].oid, &names[2].oid));
 
 	/* n = 3 is a fundamental assumption. */
 	if (n != 3)
@@ -154,10 +163,19 @@ static int collect_merge_info_callback(int n,
 		newinfo.pathlen = st_add3(newinfo.pathlen, p->pathlen, 1);
 
 		for (i = 0; i < 3; i++, dirmask >>= 1) {
-			const struct object_id *oid = NULL;
-			if (dirmask & 1)
-				oid = &names[i].oid;
-			buf[i] = fill_tree_descriptor(opt->repo, t + i, oid);
+			if (i == 1 && side1_matches_mbase)
+				t[1] = t[0];
+			else if (i == 2 && side2_matches_mbase)
+				t[2] = t[0];
+			else if (i == 2 && sides_match)
+				t[2] = t[1];
+			else {
+				const struct object_id *oid = NULL;
+				if (dirmask & 1)
+					oid = &names[i].oid;
+				buf[i] = fill_tree_descriptor(opt->repo,
+							      t + i, oid);
+			}
 		}
 
 		original_dir_name = opti->current_dir_name;
-- 
2.29.1.56.ga287c268e6.dirty


  parent reply	other threads:[~2020-10-30  3:42 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-30  3:41 [PATCH 00/20] fundamentals of merge-ort implementation Elijah Newren
2020-10-30  3:41 ` [PATCH 01/20] merge-ort: setup basic internal data structures Elijah Newren
2020-10-30  3:41 ` [PATCH 02/20] merge-ort: add some high-level algorithm structure Elijah Newren
2020-10-30  3:41 ` [PATCH 03/20] merge-ort: port merge_start() from merge-recursive Elijah Newren
2020-10-30  3:41 ` [PATCH 04/20] merge-ort: use histogram diff Elijah Newren
2020-10-30  3:41 ` [PATCH 05/20] merge-ort: add an err() function similar to one from merge-recursive Elijah Newren
2020-10-30  3:41 ` [PATCH 06/20] merge-ort: implement a very basic collect_merge_info() Elijah Newren
2020-10-30  3:41 ` Elijah Newren [this message]
2020-10-30  3:41 ` [PATCH 08/20] merge-ort: compute a few more useful fields for collect_merge_info Elijah Newren
2020-10-30  3:41 ` [PATCH 09/20] merge-ort: record stage and auxiliary info for every path Elijah Newren
2020-10-30  3:41 ` [PATCH 10/20] merge-ort: avoid recursing into identical trees Elijah Newren
2020-10-30  3:41 ` [PATCH 11/20] merge-ort: add a preliminary simple process_entries() implementation Elijah Newren
2020-10-30  3:41 ` [PATCH 12/20] merge-ort: have process_entries operate in a defined order Elijah Newren
2020-10-30  3:41 ` [PATCH 13/20] merge-ort: step 1 of tree writing -- record basenames, modes, and oids Elijah Newren
2020-10-30  3:41 ` [PATCH 14/20] merge-ort: step 2 of tree writing -- function to create tree object Elijah Newren
2020-10-30  3:41 ` [PATCH 15/20] merge-ort: step 3 of tree writing -- handling subdirectories as we go Elijah Newren
2020-10-30  3:41 ` [PATCH 16/20] merge-ort: basic outline for merge_switch_to_result() Elijah Newren
2020-10-30  3:41 ` [PATCH 17/20] merge-ort: add implementation of checkout() Elijah Newren
2020-10-30  3:41 ` [PATCH 18/20] tree: enable cmp_cache_name_compare() to be used elsewhere Elijah Newren
2020-10-30  3:41 ` [PATCH 19/20] merge-ort: add implementation of record_unmerged_index_entries() Elijah Newren
2020-10-30  3:41 ` [PATCH 20/20] merge-ort: free data structures in merge_finalize() Elijah Newren
2020-10-30  3:58 ` [PATCH 00/20] fundamentals of merge-ort implementation Elijah Newren
2020-11-29  7:43 Elijah Newren via GitGitGadget
2020-11-29  7:43 ` [PATCH 07/20] merge-ort: avoid repeating fill_tree_descriptor() on the same tree Elijah Newren via GitGitGadget

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