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[PATCH v3 17/21] ref_store: implement `refs_peel_ref()` generically

From
Michael Haggerty <mhagger@alum.mit.edu>
Date
Sep 25, 2017, 08:00 UTC
Message-ID
<b9c1f576a02d52df52ded4324f909568b94d3851.1506325610.git.mhagger@alum.mit.edu>
In-Reply-To
<cover.1506325610.git.mhagger@alum.mit.edu>

We're about to stop storing packed refs in a `ref_cache`. That means that the only way we have left to optimize `peel_ref()` is by checking whether the reference being peeled is the one currently being iterated over (in `current_ref_iter`), and if so, using `ref_iterator_peel()`. But this can be done generically; it doesn't have to be implemented per-backend.

So implement `refs_peel_ref()` in `refs.c` and remove the `peel_ref()` method from the refs API.

This removes the last callers of a couple of functions, so delete them. More cleanup to come...

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
---
 refs.c                | 18 +++++++++++++++++-
 refs/files-backend.c  | 38 --------------------------------------
 refs/packed-backend.c | 36 ------------------------------------
 refs/refs-internal.h  |  3 ---
 4 files changed, 17 insertions(+), 78 deletions(-)
diff --git a/refs.c b/refs.c
index 101c107ee8..c5e6f79c77 100644
--- a/refs.c
+++ b/refs.c
@@ -1735,7 +1735,23 @@ int refs_pack_refs(struct ref_store *refs, unsigned int flags)
 int refs_peel_ref(struct ref_store *refs, const char *refname,
 		  unsigned char *sha1)
 {
-	return refs->be->peel_ref(refs, refname, sha1);
+	int flag;
+	unsigned char base[20];
+
+	if (current_ref_iter && current_ref_iter->refname == refname) {
+		struct object_id peeled;
+
+		if (ref_iterator_peel(current_ref_iter, &peeled))
+			return -1;
+		hashcpy(sha1, peeled.hash);
+		return 0;
+	}
+
+	if (refs_read_ref_full(refs, refname,
+			       RESOLVE_REF_READING, base, &flag))
+		return -1;
+
+	return peel_object(base, sha1);
 }
 
 int peel_ref(const char *refname, unsigned char *sha1)
diff --git a/refs/files-backend.c b/refs/files-backend.c
index 35648c89fc..7d12de88d0 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -655,43 +655,6 @@ static int lock_raw_ref(struct files_ref_store *refs,
 	return ret;
 }
 
-static int files_peel_ref(struct ref_store *ref_store,
-			  const char *refname, unsigned char *sha1)
-{
-	struct files_ref_store *refs =
-		files_downcast(ref_store, REF_STORE_READ | REF_STORE_ODB,
-			       "peel_ref");
-	int flag;
-	unsigned char base[20];
-
-	if (current_ref_iter && current_ref_iter->refname == refname) {
-		struct object_id peeled;
-
-		if (ref_iterator_peel(current_ref_iter, &peeled))
-			return -1;
-		hashcpy(sha1, peeled.hash);
-		return 0;
-	}
-
-	if (refs_read_ref_full(ref_store, refname,
-			       RESOLVE_REF_READING, base, &flag))
-		return -1;
-
-	/*
-	 * If the reference is packed, read its ref_entry from the
-	 * cache in the hope that we already know its peeled value.
-	 * We only try this optimization on packed references because
-	 * (a) forcing the filling of the loose reference cache could
-	 * be expensive and (b) loose references anyway usually do not
-	 * have REF_KNOWS_PEELED.
-	 */
-	if (flag & REF_ISPACKED &&
-	    !refs_peel_ref(refs->packed_ref_store, refname, sha1))
-		return 0;
-
-	return peel_object(base, sha1);
-}
-
 struct files_ref_iterator {
 	struct ref_iterator base;
 
@@ -3012,7 +2975,6 @@ struct ref_storage_be refs_be_files = {
 	files_initial_transaction_commit,
 
 	files_pack_refs,
-	files_peel_ref,
 	files_create_symref,
 	files_delete_refs,
 	files_rename_ref,
diff --git a/refs/packed-backend.c b/refs/packed-backend.c
index be614e79f5..dbbba45502 100644
--- a/refs/packed-backend.c
+++ b/refs/packed-backend.c
@@ -850,26 +850,6 @@ static struct packed_ref_cache *get_packed_ref_cache(struct packed_ref_store *re
 	return refs->cache;
 }
 
-static struct ref_dir *get_packed_ref_dir(struct packed_ref_cache *packed_ref_cache)
-{
-	return get_ref_dir(packed_ref_cache->cache->root);
-}
-
-static struct ref_dir *get_packed_refs(struct packed_ref_store *refs)
-{
-	return get_packed_ref_dir(get_packed_ref_cache(refs));
-}
-
-/*
- * Return the ref_entry for the given refname from the packed
- * references.  If it does not exist, return NULL.
- */
-static struct ref_entry *get_packed_ref(struct packed_ref_store *refs,
-					const char *refname)
-{
-	return find_ref_entry(get_packed_refs(refs), refname);
-}
-
 static int packed_read_raw_ref(struct ref_store *ref_store,
 			       const char *refname, unsigned char *sha1,
 			       struct strbuf *referent, unsigned int *type)
@@ -896,21 +876,6 @@ static int packed_read_raw_ref(struct ref_store *ref_store,
 	return 0;
 }
 
-static int packed_peel_ref(struct ref_store *ref_store,
-			   const char *refname, unsigned char *sha1)
-{
-	struct packed_ref_store *refs =
-		packed_downcast(ref_store, REF_STORE_READ | REF_STORE_ODB,
-				"peel_ref");
-	struct ref_entry *r = get_packed_ref(refs, refname);
-
-	if (!r || peel_entry(r, 0))
-		return -1;
-
-	hashcpy(sha1, r->u.value.peeled.hash);
-	return 0;
-}
-
 struct packed_ref_iterator {
 	struct ref_iterator base;
 
@@ -1597,7 +1562,6 @@ struct ref_storage_be refs_be_packed = {
 	packed_initial_transaction_commit,
 
 	packed_pack_refs,
-	packed_peel_ref,
 	packed_create_symref,
 	packed_delete_refs,
 	packed_rename_ref,
diff --git a/refs/refs-internal.h b/refs/refs-internal.h
index d7f233beba..cc6c373f59 100644
--- a/refs/refs-internal.h
+++ b/refs/refs-internal.h
@@ -562,8 +562,6 @@ typedef int ref_transaction_commit_fn(struct ref_store *refs,
 				      struct strbuf *err);
 
 typedef int pack_refs_fn(struct ref_store *ref_store, unsigned int flags);
-typedef int peel_ref_fn(struct ref_store *ref_store,
-			const char *refname, unsigned char *sha1);
 typedef int create_symref_fn(struct ref_store *ref_store,
 			     const char *ref_target,
 			     const char *refs_heads_master,
@@ -668,7 +666,6 @@ struct ref_storage_be {
 	ref_transaction_commit_fn *initial_transaction_commit;
 
 	pack_refs_fn *pack_refs;
-	peel_ref_fn *peel_ref;
 	create_symref_fn *create_symref;
 	delete_refs_fn *delete_refs;
 	rename_ref_fn *rename_ref;

-- 
2.14.1
Previous: Michael HaggertyNext: Michael Haggerty
Message 18 of 24 in “Read `packed-refs` using mmap()”
  1. 00/21 Read `packed-refs` using mmap()Michael Haggerty, Sep 25, 2017
  2. 01/21 ref_iterator: keep track of whether the iterator output is orderedMichael Haggerty, Sep 25, 2017
  3. 02/21 prefix_ref_iterator: break when we leave the prefixMichael Haggerty, Sep 25, 2017
  4. 03/21 packed_ref_cache: add a backlink to the associated `packed_ref_store`Michael Haggerty, Sep 25, 2017
  5. 04/21 die_unterminated_line(), die_invalid_line(): new functionsMichael Haggerty, Sep 25, 2017
  6. 05/21 read_packed_refs(): use mmap to read the `packed-refs` fileMichael Haggerty, Sep 25, 2017
  7. 06/21 read_packed_refs(): only check for a header at the top of the fileMichael Haggerty, Sep 25, 2017
  8. 07/21 read_packed_refs(): make parsing of the header line more robustMichael Haggerty, Sep 25, 2017
  9. 09/21 packed_ref_cache: remember the file-wide peeling stateMichael Haggerty, Sep 25, 2017
  10. 08/21 read_packed_refs(): read references with minimal copyingMichael Haggerty, Sep 25, 2017
  11. 10/21 mmapped_ref_iterator: add iterator over a packed-refs fileMichael Haggerty, Sep 25, 2017
  12. 12/21 packed-backend.c: reorder some definitionsMichael Haggerty, Sep 25, 2017
  13. 13/21 packed_ref_cache: keep the `packed-refs` file mmapped if possibleMichael Haggerty, Sep 25, 2017
  14. 14/21 read_packed_refs(): ensure that references are ordered when readMichael Haggerty, Sep 25, 2017
  15. 11/21 mmapped_ref_iterator_advance(): no peeled value for broken refsMichael Haggerty, Sep 25, 2017
  16. 15/21 packed_ref_iterator_begin(): iterate using `mmapped_ref_iterator`Michael Haggerty, Sep 25, 2017
  17. 16/21 packed_read_raw_ref(): read the reference from the mmapped bufferMichael Haggerty, Sep 25, 2017
  18. 17/21 ref_store: implement `refs_peel_ref()` genericallyMichael Haggerty, Sep 25, 2017
  19. 18/21 packed_ref_store: get rid of the `ref_cache` entirelyMichael Haggerty, Sep 25, 2017
  20. 20/21 mmapped_ref_iterator: inline into `packed_ref_iterator`Michael Haggerty, Sep 25, 2017
  21. 19/21 ref_cache: remove support for storing peeled valuesMichael Haggerty, Sep 25, 2017
  22. 21/21 packed-backend.c: rename a bunch of things and update commentsMichael Haggerty, Sep 25, 2017
  23. Jeff KingSep 25, 2017
  24. Junio C HamanoSep 29, 2017

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