[PATCH 3/3] sha1_name: Parse less while finding common prefix
From: Derrick Stolee <hidden>
Date: 2017-09-15 16:58:30
Subsystem:
the rest · Maintainer:
Linus Torvalds
Create get_hex_char_from_oid() to parse oids one hex character at a time. This prevents unnecessary copying of hex characters in extend_abbrev_len() when finding the length of a common prefix. This change decreases the time to run test-abbrev by up to 40% on large repos. Signed-off-by: Derrick Stolee <redacted> --- sha1_name.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/sha1_name.c b/sha1_name.c
index f2a1ebe49..bb47b6702 100644
--- a/sha1_name.c
+++ b/sha1_name.c@@ -480,13 +480,22 @@ struct min_abbrev_data { char *hex; }; +static inline char get_hex_char_from_oid(const struct object_id *oid, int i) +{ + static const char hex[] = "0123456789abcdef"; + + if ((i & 1) == 0) + return hex[oid->hash[i >> 1] >> 4]; + else + return hex[oid->hash[i >> 1] & 0xf]; +} + static int extend_abbrev_len(const struct object_id *oid, void *cb_data) { struct min_abbrev_data *mad = cb_data; - char *hex = oid_to_hex(oid); unsigned int i = mad->init_len; - while (mad->hex[i] && mad->hex[i] == hex[i]) + while (mad->hex[i] && mad->hex[i] == get_hex_char_from_oid(oid, i)) i++; if (i < GIT_MAX_RAWSZ && i >= mad->cur_len)
--
2.14.1.538.g56ec8fc98.dirty