[PATCH] blame.c: don't drop origin blobs as eagerly

[David Kastrup <dak@gnu.org>]

When a parent blob already has chunks queued up for blaming, dropping
the blob at the end of one blame step will cause it to get reloaded
right away, doubling the amount of I/O and unpacking when processing a
linear history.

Keeping such parent blobs in memory seems like a reasonable optimization
that should incur additional memory pressure mostly when processing the
merges from old branches.

Signed-off-by: David Kastrup <dak@gnu.org>
---
 blame.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/blame.c b/blame.c
index 5c07dec190..c11c516921 100644
--- a/blame.c
+++ b/blame.c
@@ -1562,7 +1562,8 @@ static void pass_blame(struct blame_scoreboard *sb, struct blame_origin *origin,
 	}
 	for (i = 0; i < num_sg; i++) {
 		if (sg_origin[i]) {
-			drop_origin_blob(sg_origin[i]);
+			if (!sg_origin[i]->suspects)
+				drop_origin_blob(sg_origin[i]);
 			blame_origin_decref(sg_origin[i]);
 		}
 	}
-- 
2.20.1