refs: implement simple transactions for the packed-refs file

[thirdparty/git.git] / refs.h

diff --git a/refs.h b/refs.h
index 246bf6096d222a0d822d621de519ca5c49b0f641..9e5db3ae26ec7898d8ee9083c37562d3af05c0ab 100644 (file)
--- a/refs.h
+++ b/refs.h
@@ -77,11 +77,33 @@ extern int for_each_rawref(each_ref_fn, void *);
 extern void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refname);
 
 /*
- * Add a reference to the in-memory packed reference cache.  To actually
- * write the reference to the packed-refs file, call pack_refs().
+ * Lock the packed-refs file for writing.  Flags is passed to
+ * hold_lock_file_for_update().  Return 0 on success.
+ */
+extern int lock_packed_refs(int flags);
+
+/*
+ * Add a reference to the in-memory packed reference cache.  This may
+ * only be called while the packed-refs file is locked (see
+ * lock_packed_refs()).  To actually write the packed-refs file, call
+ * commit_packed_refs().
  */
 extern void add_packed_ref(const char *refname, const unsigned char *sha1);
 
+/*
+ * Write the current version of the packed refs cache from memory to
+ * disk.  The packed-refs file must already be locked for writing (see
+ * lock_packed_refs()).  Return zero on success.
+ */
+extern int commit_packed_refs(void);
+
+/*
+ * Rollback the lockfile for the packed-refs file, and discard the
+ * in-memory packed reference cache.  (The packed-refs file will be
+ * read anew if it is needed again after this function is called.)
+ */
+extern void rollback_packed_refs(void);
+
 /*
  * Flags for controlling behaviour of pack_refs()
  * PACK_REFS_PRUNE: Prune loose refs after packing