[PATCH v2 14/21] read-cache: touch shared index files when used

[Christian Couder]

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 <chrisc...@tuxfamily.org>
---
 read-cache.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/read-cache.c b/read-cache.c
index 280b01bd6c..42688261f7 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -1685,6 +1685,19 @@ int do_read_index(struct index_state *istate, const char 
*path, int must_exist)
        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. It's ok to fail to update the mtime if we are on a
+ * read only file system.
+ */
+void freshen_shared_index(char *base_sha1_hex)
+{
+       const char *shared_index = git_path("sharedindex.%s", base_sha1_hex);
+       check_and_freshen_file(shared_index, 1);
+}
+
 int read_index_from(struct index_state *istate, const char *path)
 {
        struct split_index *split_index;
@@ -2276,6 +2289,8 @@ int write_locked_index(struct index_state *istate, struct 
lock_file *lock,
                int ret = write_shared_index(istate, lock, flags);
                if (ret)
                        return ret;
+       } else {
+               freshen_shared_index(sha1_to_hex(si->base_sha1));
        }
 
        return write_split_index(istate, lock, flags);
-- 
2.11.0.49.g2414764.dirty