read-cache: touch shared index files when used

When a split-index file is created, let's update the mtime of the
shared index file that the split-index file is referencing.

In a following commit we will make shared index file expire
depending on their mtime, so updating the mtime makes sure that
the shared index file will not be deleted soon.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/read-cache.c b/read-cache.c
index fd1c88aa0f52911dd3171e502887968eb187d8ea..5ea6cee8ff260512d501145fe61473b41dd28fe0 100644 (file)
--- a/read-cache.c
+++ b/read-cache.c
@@ -1682,6 +1682,19 @@ unmap:
        die("index file corrupt");
 }
 
+/*
+ * Signal that the shared index is used by updating its mtime.
+ *
+ * This way, shared index can be removed if they have not been used
+ * for some time.
+ */
+static void freshen_shared_index(char *base_sha1_hex, int warn)
+{
+       const char *shared_index = git_path("sharedindex.%s", base_sha1_hex);
+       if (!check_and_freshen_file(shared_index, 1) && warn)
+               warning("could not freshen shared index '%s'", shared_index);
+}
+
 int read_index_from(struct index_state *istate, const char *path)
 {
        struct split_index *split_index;
@@ -2253,6 +2266,7 @@ static int too_many_not_shared_entries(struct index_state *istate)
 int write_locked_index(struct index_state *istate, struct lock_file *lock,
                       unsigned flags)
 {
+       int new_shared_index, ret;
        struct split_index *si = istate->split_index;
 
        if (!si || alternate_index_output ||
@@ -2269,13 +2283,22 @@ int write_locked_index(struct index_state *istate, struct lock_file *lock,
        }
        if (too_many_not_shared_entries(istate))
                istate->cache_changed |= SPLIT_INDEX_ORDERED;
-       if (istate->cache_changed & SPLIT_INDEX_ORDERED) {
-               int ret = write_shared_index(istate, lock, flags);
+
+       new_shared_index = istate->cache_changed & SPLIT_INDEX_ORDERED;
+
+       if (new_shared_index) {
+               ret = write_shared_index(istate, lock, flags);
                if (ret)
                        return ret;
        }
 
-       return write_split_index(istate, lock, flags);
+       ret = write_split_index(istate, lock, flags);
+
+       /* Freshen the shared index only if the split-index was written */
+       if (!ret && !new_shared_index)
+               freshen_shared_index(sha1_to_hex(si->base_sha1), 1);
+
+       return ret;
 }
 
 /*