Subject: [RFC/PATCH 1/2] Avoid rescanning unchanged entries in search for copies.

From: Alexander Gavrilov <[email-masked]>
Date: Wed, 16 Jul 2008 01:59:56 +0400

Repeatedly comparing the same entry against the same set
of blobs in search for copies is quite pointless. This
huge waste of effort can be avoided using a flag in
the blame_entry structure.

Signed-off-by: Alexander Gavrilov <[email-masked]>
---
 builtin-blame.c |   21 +++++++++++++++++++--
 1 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/builtin-blame.c b/builtin-blame.c
index b451f6c..a6cf6b6 100644
--- a/builtin-blame.c
+++ b/builtin-blame.c
@@ -161,6 +161,10 @@ struct blame_entry {
 	 */
 	char guilty;
 
+	/* true if the entry has been scanned for copies in the current parent
+	 */
+	char scanned;
+
 	/* the line number of the first line of this group in the
 	 * suspect's file; internally all line numbers are 0 based.
 	 */
@@ -1048,12 +1052,12 @@ static struct blame_list *setup_blame_list(struct 
scoreboard *sb,
 	struct blame_list *blame_list = NULL;
 
 	for (e = sb->ent, num_ents = 0; e; e = e->next)
-		if (!e->guilty && same_suspect(e->suspect, target))
+		if (!e->scanned && !e->guilty && same_suspect(e->suspect, target))
 			num_ents++;
 	if (num_ents) {
 		blame_list = xcalloc(num_ents, sizeof(struct blame_list));
 		for (e = sb->ent, i = 0; e; e = e->next)
-			if (!e->guilty && same_suspect(e->suspect, target))
+			if (!e->scanned && !e->guilty && same_suspect(e->suspect, target))
 				blame_list[i++].ent = e;
 	}
 	*num_ents_p = num_ents;
@@ -1061,6 +1065,16 @@ static struct blame_list *setup_blame_list(struct 
scoreboard *sb,
 }
 
 /*
+ * Reset the scanned status on all entries.
+ */
+static void reset_scanned_flag(struct scoreboard *sb)
+{
+	struct blame_entry *e;
+	for (e = sb->ent; e; e = e->next)
+		e->scanned = 0;
+}
+
+/*
  * For lines target is suspected for, see if we can find code movement
  * across file boundary from the parent commit.  porigin is the path
  * in the parent we already tried.
@@ -1152,6 +1166,8 @@ static int find_copy_in_parent(struct scoreboard *sb,
 				split_blame(sb, split, blame_list[j].ent);
 				made_progress = 1;
 			}
+			else
+				blame_list[j].ent->scanned = 1;
 			decref_split(split);
 		}
 		free(blame_list);
@@ -1164,6 +1180,7 @@ static int find_copy_in_parent(struct scoreboard *sb,
 			break;
 		}
 	}
+	reset_scanned_flag(sb);
 	diff_flush(&diff_opts);
 	diff_tree_release_paths(&diff_opts);
 	return retval;
-- 
1.5.6.2.39.gd084