reset $pathspec: no need to discard index

Since 34110cd (Make 'unpack_trees()' have a separate source and
destination index, 2008-03-06), the index no longer gets clobbered by
do_diff_cache() and we can remove the code for discarding and
re-reading it.

There are two paths to update_index_refresh() from cmd_reset(), but on
both paths, either read_cache() or read_cache_unmerged() will have
been called, so the call to read_cache() in this method is redundant
(although practically free).

This speeds up "git reset -- ." a little on the linux-2.6 repo (best
of five, warm cache):

Before      After
real    0m0.093s    0m0.080s
user    0m0.040s    0m0.020s
sys     0m0.050s    0m0.050s

Signed-off-by: Martin von Zweigbergk <martinvonz@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/reset.c b/builtin/reset.c
index 915cc9f86f855d517abaa55d31c502899fb77220..8cc7c722ef1c4912aac18d5dddb6aaf31a755ce2 100644 (file)
--- a/builtin/reset.c
+++ b/builtin/reset.c
@@ -126,9 +126,6 @@ static int update_index_refresh(int fd, struct lock_file *index_lock, int flags)
                fd = hold_locked_index(index_lock, 1);
        }
 
-       if (read_cache() < 0)
-               return error(_("Could not read index"));
-
        result = refresh_index(&the_index, (flags), NULL, NULL,
                               _("Unstaged changes after reset:")) ? 1 : 0;
        if (write_cache(fd, active_cache, active_nr) ||
@@ -141,12 +138,6 @@ static void update_index_from_diff(struct diff_queue_struct *q,
                struct diff_options *opt, void *data)
 {
        int i;
-       int *discard_flag = data;
-
-       /* do_diff_cache() mangled the index */
-       discard_cache();
-       *discard_flag = 1;
-       read_cache();
 
        for (i = 0; i < q->nr; i++) {
                struct diff_filespec *one = q->queue[i]->one;
@@ -179,17 +170,15 @@ static int read_from_tree(const char *prefix, const char **argv,
                unsigned char *tree_sha1, int refresh_flags)
 {
        struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
-       int index_fd, index_was_discarded = 0;
+       int index_fd;
        struct diff_options opt;
 
        memset(&opt, 0, sizeof(opt));
        diff_tree_setup_paths(get_pathspec(prefix, (const char **)argv), &opt);
        opt.output_format = DIFF_FORMAT_CALLBACK;
        opt.format_callback = update_index_from_diff;
-       opt.format_callback_data = &index_was_discarded;
 
        index_fd = hold_locked_index(lock, 1);
-       index_was_discarded = 0;
        read_cache();
        if (do_diff_cache(tree_sha1, &opt))
                return 1;
@@ -197,9 +186,6 @@ static int read_from_tree(const char *prefix, const char **argv,
        diff_flush(&opt);
        diff_tree_release_paths(&opt);
 
-       if (!index_was_discarded)
-               /* The index is still clobbered from do_diff_cache() */
-               discard_cache();
        return update_index_refresh(index_fd, lock, refresh_flags);
 }