From 7dc24aa5a62cc5f77e6637674581c837f4bdf78e Mon Sep 17 00:00:00 2001
From: "Shawn O. Pearce" <spearce@spearce.org>
Date: Sat, 26 May 2007 01:24:40 -0400
Subject: [PATCH] Micro-optimize prepare_alt_odb

Calling getenv() is not that expensive, but its also not free,
and its certainly not cheaper than testing to see if alt_odb_tail
is not null.

Because we are calling prepare_alt_odb() from within find_sha1_file
every time we cannot find an object file locally we want to skip out
of prepare_alt_odb() as early as possible once we have initialized
our alternate list.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
---
 sha1_file.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/sha1_file.c b/sha1_file.c
index 6a5ba63500..a3637d7e5b 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -376,11 +376,12 @@ void prepare_alt_odb(void)
 {
 	const char *alt;
 
+	if (alt_odb_tail)
+		return;
+
 	alt = getenv(ALTERNATE_DB_ENVIRONMENT);
 	if (!alt) alt = "";
 
-	if (alt_odb_tail)
-		return;
 	alt_odb_tail = &alt_odb_list;
 	link_alt_odb_entries(alt, alt + strlen(alt), ':', NULL, 0);
 
-- 
2.40.0