Merge branch 'ma/skip-writing-unchanged-index'

Internal API clean-up to allow write_locked_index() optionally skip
writing the in-core index when it is not modified.

* ma/skip-writing-unchanged-index:
  write_locked_index(): add flag to avoid writing unchanged index

1 files changed, 4 insertions, 0 deletions

diff --git a/cache.h b/cache.h
index d06932ed0b..a61b2d3f0d 100644
--- a/cache.h
+++ b/cache.h
@@ -599,6 +599,7 @@ extern int read_index_unmerged(struct index_state *);
 
 /* For use with `write_locked_index()`. */
 #define COMMIT_LOCK		(1 << 0)
+#define SKIP_IF_UNCHANGED	(1 << 1)
 
 /*
  * Write the index while holding an already-taken lock. Close the lock,
@@ -615,6 +616,9 @@ extern int read_index_unmerged(struct index_state *);
  * With `COMMIT_LOCK`, the lock is always committed or rolled back.
  * Without it, the lock is closed, but neither committed nor rolled
  * back.
+ *
+ * If `SKIP_IF_UNCHANGED` is given and the index is unchanged, nothing
+ * is written (and the lock is rolled back if `COMMIT_LOCK` is given).
  */
 extern int write_locked_index(struct index_state *, struct lock_file *lock, unsigned flags);