Merge branch 'ps/ref-peeled-tags' into kn/refs-optim-cleanup

* ps/ref-peeled-tags: (92 commits)
  t7004: do not chdir around in the main process
  ref-filter: fix stale parsed objects
  ref-filter: parse objects on demand
  ref-filter: detect broken tags when dereferencing them
  refs: don't store peeled object IDs for invalid tags
  object: add flag to `peel_object()` to verify object type
  refs: drop infrastructure to peel via iterators
  refs: drop `current_ref_iter` hack
  builtin/show-ref: convert to use `reference_get_peeled_oid()`
  ref-filter: propagate peeled object ID
  upload-pack: convert to use `reference_get_peeled_oid()`
  refs: expose peeled object ID via the iterator
  refs: refactor reference status flags
  refs: fully reset `struct ref_iterator::ref` on iteration
  refs: introduce `.ref` field for the base iterator
  refs: introduce wrapper struct for `each_ref_fn`
  builtin/repo: add progress meter for structure stats
  builtin/repo: add keyvalue and nul format for structure stats
  builtin/repo: add object counts in structure output
  builtin/repo: introduce structure subcommand
  ...

1 files changed, 56 insertions, 32 deletions

diff --git a/refs.h b/refs.h
index 4e6bd63aa8..2dd7ac1a16 100644
--- a/refs.h
+++ b/refs.h
@@ -333,36 +333,74 @@ struct ref_transaction;
  * stored in ref_iterator::flags. Other bits are for internal use
  * only:
  */
+enum reference_status {
+	/* Reference is a symbolic reference. */
+	REF_ISSYMREF = (1 << 0),
 
-/* Reference is a symbolic reference. */
-#define REF_ISSYMREF 0x01
+	/* Reference is a packed reference. */
+	REF_ISPACKED = (1 << 1),
 
-/* Reference is a packed reference. */
-#define REF_ISPACKED 0x02
+	/*
+	 * Reference cannot be resolved to an object name: dangling symbolic
+	 * reference (directly or indirectly), corrupt reference file,
+	 * reference exists but name is bad, or symbolic reference refers to
+	 * ill-formatted reference name.
+	 */
+	REF_ISBROKEN = (1 << 2),
 
-/*
- * Reference cannot be resolved to an object name: dangling symbolic
- * reference (directly or indirectly), corrupt reference file,
- * reference exists but name is bad, or symbolic reference refers to
- * ill-formatted reference name.
- */
-#define REF_ISBROKEN 0x04
+	/*
+	 * Reference name is not well formed.
+	 *
+	 * See git-check-ref-format(1) for the definition of well formed ref names.
+	 */
+	REF_BAD_NAME = (1 << 3),
+};
+
+/* A reference passed to `for_each_ref()`-style callbacks. */
+struct reference {
+	/* The fully-qualified name of the reference. */
+	const char *name;
+
+	/* The target of a symbolic ref. `NULL` for direct references. */
+	const char *target;
+
+	/*
+	 * The object ID of a reference. Either the direct object ID or the
+	 * resolved object ID in the case of a symbolic ref. May be the zero
+	 * object ID in case the symbolic ref cannot be resolved.
+	 */
+	const struct object_id *oid;
+
+	/*
+	 * An optional peeled object ID. This field _may_ be set for tags in
+	 * case the peeled value is present in the backend. Please refer to
+	 * `reference_get_peeled_oid()`.
+	 */
+	const struct object_id *peeled_oid;
+
+	/* A bitfield of `enum reference_status` flags. */
+	unsigned flags;
+};
 
 /*
- * Reference name is not well formed.
+ * Peel the tag to a non-tag commit. If present, this uses the peeled object ID
+ * exposed by the reference backend. Otherwise, the object is peeled via the
+ * object database, which is less efficient.
  *
- * See git-check-ref-format(1) for the definition of well formed ref names.
+ * Return `0` if the reference could be peeled, a negative error code
+ * otherwise.
  */
-#define REF_BAD_NAME 0x08
+int reference_get_peeled_oid(struct repository *repo,
+			     const struct reference *ref,
+			     struct object_id *peeled_oid);
 
 /*
  * The signature for the callback function for the for_each_*()
- * functions below.  The memory pointed to by the refname and oid
- * arguments is only guaranteed to be valid for the duration of a
+ * functions below.  The memory pointed to by the `struct reference`
+ * argument is only guaranteed to be valid for the duration of a
  * single callback invocation.
  */
-typedef int each_ref_fn(const char *refname, const char *referent,
-			const struct object_id *oid, int flags, void *cb_data);
+typedef int each_ref_fn(const struct reference *ref, void *cb_data);
 
 /*
  * The following functions invoke the specified callback function for
@@ -1251,10 +1289,6 @@ int repo_migrate_ref_storage_format(struct repository *repo,
  * to the next entry, ref_iterator_advance() aborts the iteration,
  * frees the ref_iterator, and returns ITER_ERROR.
  *
- * The reference currently being looked at can be peeled by calling
- * ref_iterator_peel(). This function is often faster than peel_ref(),
- * so it should be preferred when iterating over references.
- *
  * Putting it all together, a typical iteration looks like this:
  *
  *     int ok;
@@ -1269,9 +1303,6 @@ int repo_migrate_ref_storage_format(struct repository *repo,
  *             // Access information about the current reference:
  *             if (!(iter->flags & REF_ISSYMREF))
  *                     printf("%s is %s\n", iter->refname, oid_to_hex(iter->oid));
- *
- *             // If you need to peel the reference:
- *             ref_iterator_peel(iter, &oid);
  *     }
  *
  *     if (ok != ITER_DONE)
@@ -1362,13 +1393,6 @@ enum ref_iterator_seek_flag {
 int ref_iterator_seek(struct ref_iterator *ref_iterator, const char *refname,
 		      unsigned int flags);
 
-/*
- * If possible, peel the reference currently being viewed by the
- * iterator. Return 0 on success.
- */
-int ref_iterator_peel(struct ref_iterator *ref_iterator,
-		      struct object_id *peeled);
-
 /* Free the reference iterator and any associated resources. */
 void ref_iterator_free(struct ref_iterator *ref_iterator);