[PATCH 6/6] packed_ref_cache: don't use mmap() for small files

[Michael Haggerty]

From: Kim Gybels <kgyb...@infogroep.be>

Take a hint from commit ea68b0ce9f8 (hash-object: don't use mmap() for
small files, 2010-02-21) and use read() instead of mmap() for small
packed-refs files.

Signed-off-by: Kim Gybels <kgyb...@infogroep.be>
Signed-off-by: Junio C Hamano <gits...@pobox.com>
Signed-off-by: Michael Haggerty <mhag...@alum.mit.edu>
---
 refs/packed-backend.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/refs/packed-backend.c b/refs/packed-backend.c
index e829cf206d..8b4b45da67 100644
--- a/refs/packed-backend.c
+++ b/refs/packed-backend.c
@@ -458,6 +458,8 @@ static void verify_buffer_safe(struct snapshot *snapshot)
                                 last_line, eof - last_line);
 }
 
+#define SMALL_FILE_SIZE (32*1024)
+
 /*
  * Depending on `mmap_strategy`, either mmap or read the contents of
  * the `packed-refs` file into the snapshot. Return 1 if the file
@@ -495,7 +497,7 @@ static int load_contents(struct snapshot *snapshot)
 
        if (!size) {
                return 0;
-       } else if (mmap_strategy == MMAP_NONE) {
+       } else if (mmap_strategy == MMAP_NONE || size <= SMALL_FILE_SIZE) {
                snapshot->buf = xmalloc(size);
                bytes_read = read_in_full(fd, snapshot->buf, size);
                if (bytes_read < 0 || bytes_read != size)
-- 
2.14.2