Merge branch 'mh/mmap-packed-refs'

Operations that do not touch (majority of) packed refs have been
optimized by making accesses to packed-refs file lazy; we no longer
pre-parse everything, and an access to a single ref in the
packed-refs does not touch majority of irrelevant refs, either.

* mh/mmap-packed-refs: (21 commits)
  packed-backend.c: rename a bunch of things and update comments
  mmapped_ref_iterator: inline into `packed_ref_iterator`
  ref_cache: remove support for storing peeled values
  packed_ref_store: get rid of the `ref_cache` entirely
  ref_store: implement `refs_peel_ref()` generically
  packed_read_raw_ref(): read the reference from the mmapped buffer
  packed_ref_iterator_begin(): iterate using `mmapped_ref_iterator`
  read_packed_refs(): ensure that references are ordered when read
  packed_ref_cache: keep the `packed-refs` file mmapped if possible
  packed-backend.c: reorder some definitions
  mmapped_ref_iterator_advance(): no peeled value for broken refs
  mmapped_ref_iterator: add iterator over a packed-refs file
  packed_ref_cache: remember the file-wide peeling state
  read_packed_refs(): read references with minimal copying
  read_packed_refs(): make parsing of the header line more robust
  read_packed_refs(): only check for a header at the top of the file
  read_packed_refs(): use mmap to read the `packed-refs` file
  die_unterminated_line(), die_invalid_line(): new functions
  packed_ref_cache: add a backlink to the associated `packed_ref_store`
  prefix_ref_iterator: break when we leave the prefix
  ...

1 files changed, 4 insertions, 31 deletions

diff --git a/refs/ref-cache.h b/refs/ref-cache.h
index 794f000fd3..eda65e73ed 100644
--- a/refs/ref-cache.h
+++ b/refs/ref-cache.h
@@ -38,14 +38,6 @@ struct ref_value {
 	 * referred to by the last reference in the symlink chain.
 	 */
 	struct object_id oid;
-
-	/*
-	 * If REF_KNOWS_PEELED, then this field holds the peeled value
-	 * of this reference, or null if the reference is known not to
-	 * be peelable.  See the documentation for peel_ref() for an
-	 * exact definition of "peelable".
-	 */
-	struct object_id peeled;
 };
 
 /*
@@ -97,21 +89,14 @@ struct ref_dir {
  * public values; see refs.h.
  */
 
-/*
- * The field ref_entry->u.value.peeled of this value entry contains
- * the correct peeled value for the reference, which might be
- * null_sha1 if the reference is not a tag or if it is broken.
- */
-#define REF_KNOWS_PEELED 0x10
-
 /* ref_entry represents a directory of references */
-#define REF_DIR 0x20
+#define REF_DIR 0x10
 
 /*
  * Entry has not yet been read from disk (used only for REF_DIR
  * entries representing loose references)
  */
-#define REF_INCOMPLETE 0x40
+#define REF_INCOMPLETE 0x20
 
 /*
  * A ref_entry represents either a reference or a "subdirectory" of
@@ -245,23 +230,11 @@ struct ref_entry *find_ref_entry(struct ref_dir *dir, const char *refname);
  * Start iterating over references in `cache`. If `prefix` is
  * specified, only include references whose names start with that
  * prefix. If `prime_dir` is true, then fill any incomplete
- * directories before beginning the iteration.
+ * directories before beginning the iteration. The output is ordered
+ * by refname.
  */
 struct ref_iterator *cache_ref_iterator_begin(struct ref_cache *cache,
 					      const char *prefix,
 					      int prime_dir);
 
-/*
- * Peel the entry (if possible) and return its new peel_status.  If
- * repeel is true, re-peel the entry even if there is an old peeled
- * value that is already stored in it.
- *
- * It is OK to call this function with a packed reference entry that
- * might be stale and might even refer to an object that has since
- * been garbage-collected.  In such a case, if the entry has
- * REF_KNOWS_PEELED then leave the status unchanged and return
- * PEEL_PEELED or PEEL_NON_TAG; otherwise, return PEEL_INVALID.
- */
-enum peel_status peel_entry(struct ref_entry *entry, int repeel);
-
 #endif /* REFS_REF_CACHE_H */