From c609b16cc0896ae0ee7f8e1b5eb60f07264204e8 Mon Sep 17 00:00:00 2001
From: Joel Rosdahl <joel@rosdahl.net>
Date: Sun, 9 May 2010 17:50:20 +0200
Subject: [PATCH] Rename temporary object file to cached object file if
 possible

This avoids copying the object file unnecessarily in the common case when we
store object files uncompressed in the cache.
---
 ccache.c |  5 +++--
 ccache.h |  2 ++
 util.c   | 14 ++++++++++++++
 3 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/ccache.c b/ccache.c
index b2a55c2..fe22981 100644
--- a/ccache.c
+++ b/ccache.c
@@ -594,7 +594,8 @@ static void to_cache(ARGS *args)
 		failed();
 	}
 	if (st.st_size > 0) {
-		if (move_file(tmp_stderr, cached_stderr, compress) != 0) {
+		if (move_uncompressed_file(tmp_stderr, cached_stderr,
+					   compress) != 0) {
 			cc_log("Failed to move %s to %s",
 			       tmp_stderr, cached_stderr);
 			stats_update(STATS_ERROR);
@@ -604,7 +605,7 @@ static void to_cache(ARGS *args)
 	} else {
 		unlink(tmp_stderr);
 	}
-	if (move_file(tmp_obj, cached_obj, compress) != 0) {
+	if (move_uncompressed_file(tmp_obj, cached_obj, compress) != 0) {
 		cc_log("Failed to move %s to %s", tmp_obj, cached_obj);
 		stats_update(STATS_ERROR);
 		failed();
diff --git a/ccache.h b/ccache.h
index 2277344..9aae3ff 100644
--- a/ccache.h
+++ b/ccache.h
@@ -70,6 +70,8 @@ void fatal(const char *format, ...) ATTR_FORMAT(printf, 1, 2);
 void copy_fd(int fd_in, int fd_out);
 int copy_file(const char *src, const char *dest, int compress_dest);
 int move_file(const char *src, const char *dest, int compress_dest);
+int move_uncompressed_file(const char *src, const char *dest,
+			   int compress_dest);
 int test_if_compressed(const char *filename);
 
 int create_dir(const char *dir);
diff --git a/util.c b/util.c
index 7ddd505..4ac7109 100644
--- a/util.c
+++ b/util.c
@@ -259,6 +259,20 @@ int move_file(const char *src, const char *dest, int compress_dest)
 	return ret;
 }
 
+/*
+ * Like move_file(), but assumes that src is uncompressed and that src and dest
+ * are on the same file system.
+ */
+int
+move_uncompressed_file(const char *src, const char *dest, int compress_dest)
+{
+	if (compress_dest) {
+		return move_file(src, dest, compress_dest);
+	} else {
+		return rename(src, dest);
+	}
+}
+
 /* test if a file is zlib compressed */
 int test_if_compressed(const char *filename)
 {