Commit 9ccdb21155b3c9650acf58c55b2596c3503ea14d
2013-08-13T10:55:37
fileops: stat() before open()ing in git_futils_readbuffer_updated() This reverts refactoring done in 13224ea4aad9a1b3c9cc4c992ceaea9af623e047 that introduces a performance regression for NFS when reading files that don't exist. open() forces a cache invalidation on NFS, while stat()ing a file just uses the cache and is very quick. To give a specific example, say you have a repo with a thousand packed refs. Before this change, looking up every single one ould incur a thousand slow open() calls. With this change, it's a thousand fast stat() calls.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
diff --git a/src/fileops.c b/src/fileops.c
index 7f8418d..e367ac2 100644
--- a/src/fileops.c
+++ b/src/fileops.c
@@ -147,6 +147,7 @@ int git_futils_readbuffer_fd(git_buf *buf, git_file fd, size_t len)
int git_futils_readbuffer_updated(
git_buf *buf, const char *path, time_t *mtime, size_t *size, int *updated)
{
+ int error = 0;
git_file fd;
struct stat st;
bool changed = false;
@@ -156,11 +157,15 @@ int git_futils_readbuffer_updated(
if (updated != NULL)
*updated = 0;
- if ((fd = git_futils_open_ro(path)) < 0)
- return fd;
+ if (p_stat(path, &st) < 0) {
+ error = errno;
+ giterr_set(GITERR_OS, "Failed to stat '%s'", path);
+ if (error == ENOENT || error == ENOTDIR)
+ return GIT_ENOTFOUND;
+ return -1;
+ }
- if (p_fstat(fd, &st) < 0 || S_ISDIR(st.st_mode) || !git__is_sizet(st.st_size+1)) {
- p_close(fd);
+ if (S_ISDIR(st.st_mode) || !git__is_sizet(st.st_size+1)) {
giterr_set(GITERR_OS, "Invalid regular file stat for '%s'", path);
return -1;
}
@@ -177,7 +182,6 @@ int git_futils_readbuffer_updated(
changed = true;
if (!changed) {
- p_close(fd);
return 0;
}
@@ -186,6 +190,9 @@ int git_futils_readbuffer_updated(
if (size != NULL)
*size = (size_t)st.st_size;
+ if ((fd = git_futils_open_ro(path)) < 0)
+ return fd;
+
if (git_futils_readbuffer_fd(buf, fd, (size_t)st.st_size) < 0) {
p_close(fd);
return -1;