[PATCH 4/4] ls-tree: use strbuf_add_uint()

["René Scharfe" <l.s.r@web.de>]

Speed up printing of objectsize values by using the specialized function
strbuf_add_uint() as well as strbuf_insert() for padding instead of the
general-purpose function strbuf_addf().  Here are the numbers I get when
listing objects in the Linux kernel repo:

Benchmark 1: ./git_main -C ../linux ls-tree -r --format='%(objectsize)' HEAD
  Time (mean ± σ):     294.4 ms ±   0.4 ms    [User: 231.5 ms, System: 59.4 ms]
  Range (min … max):   293.9 ms … 295.0 ms    10 runs

Benchmark 2: ./git -C ../linux ls-tree -r --format='%(objectsize)' HEAD
  Time (mean ± σ):     291.2 ms ±   0.4 ms    [User: 227.9 ms, System: 62.1 ms]
  Range (min … max):   290.6 ms … 292.0 ms    10 runs

Benchmark 3: ./git_main -C ../linux ls-tree -r --format='%(objectsize:padded)' HEAD
  Time (mean ± σ):     295.3 ms ±   0.6 ms    [User: 232.0 ms, System: 59.6 ms]
  Range (min … max):   294.3 ms … 296.3 ms    10 runs

Benchmark 4: ./git -C ../linux ls-tree -r --format='%(objectsize:padded)' HEAD
  Time (mean ± σ):     291.9 ms ±   0.4 ms    [User: 228.5 ms, System: 61.5 ms]
  Range (min … max):   291.2 ms … 292.3 ms    10 runs

Summary
  ./git -C ../linux ls-tree -r --format='%(objectsize)' HEAD ran
    1.00 ± 0.00 times faster than ./git -C ../linux ls-tree -r --format='%(objectsize:padded)' HEAD
    1.01 ± 0.00 times faster than ./git_main -C ../linux ls-tree -r --format='%(objectsize)' HEAD
    1.01 ± 0.00 times faster than ./git_main -C ../linux ls-tree -r --format='%(objectsize:padded)' HEAD

Signed-off-by: René Scharfe <l.s.r@web.de>
---
 builtin/ls-tree.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/builtin/ls-tree.c b/builtin/ls-tree.c
index 113e4a960d..57846911ce 100644
--- a/builtin/ls-tree.c
+++ b/builtin/ls-tree.c
@@ -26,20 +26,23 @@ static const char * const ls_tree_usage[] = {
 static void expand_objectsize(struct strbuf *line, const struct object_id *oid,
 			      const enum object_type type, unsigned int padded)
 {
+	static const char padding[] = "       ";
+	size_t min_len = padded ? strlen(padding) : 0;
+	size_t orig_len = line->len;
+	size_t len;
+
 	if (type == OBJ_BLOB) {
 		unsigned long size;
 		if (odb_read_object_info(the_repository->objects, oid, &size) < 0)
 			die(_("could not get object info about '%s'"),
 			    oid_to_hex(oid));
-		if (padded)
-			strbuf_addf(line, "%7"PRIuMAX, (uintmax_t)size);
-		else
-			strbuf_addf(line, "%"PRIuMAX, (uintmax_t)size);
-	} else if (padded) {
-		strbuf_addf(line, "%7s", "-");
+		strbuf_add_uint(line, size);
 	} else {
 		strbuf_addstr(line, "-");
 	}
+	len = line->len - orig_len;
+	if (len < min_len)
+		strbuf_insert(line, orig_len, padding, min_len - len);
 }
 
 struct ls_tree_options {
-- 
2.54.0