Merge branch 'ps/reftable-iteration-perf-part2'

The code to iterate over refs with the reftable backend has seen
some optimization.

* ps/reftable-iteration-perf-part2:
  refs/reftable: precompute prefix length
  reftable: allow inlining of a few functions
  reftable/record: decode keys in place
  reftable/record: reuse refname when copying
  reftable/record: reuse refname when decoding
  reftable/merged: avoid duplicate pqueue emptiness check
  reftable/merged: circumvent pqueue with single subiter
  reftable/merged: handle subiter cleanup on close only
  reftable/merged: remove unnecessary null check for subiters
  reftable/merged: make subiters own their records
  reftable/merged: advance subiter on subsequent iteration
  reftable/merged: make `merged_iter` structure private
  reftable/pq: use `size_t` to track iterator index

refs/reftable-backend.c

@@ -346,6 +346,7 @@ struct reftable_ref_iterator {
 	struct object_id oid;
 
 	const char *prefix;
+	size_t prefix_len;
 	unsigned int flags;
 	int err;
 };
@@ -374,8 +375,8 @@ static int reftable_ref_iterator_advance(struct ref_iterator *ref_iterator)
 			continue;
 		}
 
-		if (iter->prefix &&
+		if (iter->prefix_len &&
-		    strncmp(iter->prefix, iter->ref.refname, strlen(iter->prefix))) {
+		    strncmp(iter->prefix, iter->ref.refname, iter->prefix_len)) {
 			iter->err = 1;
 			break;
 		}
@@ -484,6 +485,7 @@ static struct reftable_ref_iterator *ref_iterator_for_stack(struct reftable_ref_
 	iter = xcalloc(1, sizeof(*iter));
 	base_ref_iterator_init(&iter->base, &reftable_ref_iterator_vtable);
 	iter->prefix = prefix;
+	iter->prefix_len = prefix ? strlen(prefix) : 0;
 	iter->base.oid = &iter->oid;
 	iter->flags = flags;
 	iter->refs = refs;

reftable/block.c

@@ -291,9 +291,8 @@ static int restart_key_less(size_t idx, void *args)
 	/* the restart key is verbatim in the block, so this could avoid the
 	   alloc for decoding the key */
 	struct strbuf rkey = STRBUF_INIT;
-	struct strbuf last_key = STRBUF_INIT;
 	uint8_t unused_extra;
-	int n = reftable_decode_key(&rkey, &unused_extra, last_key, in);
+	int n = reftable_decode_key(&rkey, &unused_extra, in);
 	int result;
 	if (n < 0) {
 		a->error = 1;
@@ -326,35 +325,34 @@ int block_iter_next(struct block_iter *it, struct reftable_record *rec)
 	if (it->next_off >= it->br->block_len)
 		return 1;
 
-	n = reftable_decode_key(&it->key, &extra, it->last_key, in);
+	n = reftable_decode_key(&it->last_key, &extra, in);
 	if (n < 0)
 		return -1;
-
+	if (!it->last_key.len)
-	if (!it->key.len)
 		return REFTABLE_FORMAT_ERROR;
 
 	string_view_consume(&in, n);
-	n = reftable_record_decode(rec, it->key, extra, in, it->br->hash_size);
+	n = reftable_record_decode(rec, it->last_key, extra, in, it->br->hash_size);
 	if (n < 0)
 		return -1;
 	string_view_consume(&in, n);
 
-	strbuf_swap(&it->last_key, &it->key);
 	it->next_off += start.len - in.len;
 	return 0;
 }
 
 int block_reader_first_key(struct block_reader *br, struct strbuf *key)
 {
-	struct strbuf empty = STRBUF_INIT;
+	int off = br->header_off + 4, n;
-	int off = br->header_off + 4;
 	struct string_view in = {
 		.buf = br->block.data + off,
 		.len = br->block_len - off,
 	};
-
 	uint8_t extra = 0;
-	int n = reftable_decode_key(key, &extra, empty, in);
+
+	strbuf_reset(key);
+
+	n = reftable_decode_key(key, &extra, in);
 	if (n < 0)
 		return n;
 	if (!key->len)
@@ -371,7 +369,6 @@ int block_iter_seek(struct block_iter *it, struct strbuf *want)
 void block_iter_close(struct block_iter *it)
 {
 	strbuf_release(&it->last_key);
-	strbuf_release(&it->key);
 }
 
 int block_reader_seek(struct block_reader *br, struct block_iter *it,
@@ -408,8 +405,8 @@ int block_reader_seek(struct block_reader *br, struct block_iter *it,
 		if (err < 0)
 			goto done;
 
-		reftable_record_key(&rec, &it->key);
+		reftable_record_key(&rec, &it->last_key);
-		if (err > 0 || strbuf_cmp(&it->key, want) >= 0) {
+		if (err > 0 || strbuf_cmp(&it->last_key, want) >= 0) {
 			err = 0;
 			goto done;
 		}

reftable/block.h

@@ -84,12 +84,10 @@ struct block_iter {
 
 	/* key for last entry we read. */
 	struct strbuf last_key;
-	struct strbuf key;
 };
 
 #define BLOCK_ITER_INIT { \
 	.last_key = STRBUF_INIT, \
-	.key = STRBUF_INIT, \
 }
 
 /* initializes a block reader. */

reftable/iter.c

@@ -16,11 +16,6 @@ https://developers.google.com/open-source/licenses/bsd
 #include "reader.h"
 #include "reftable-error.h"
 
-int iterator_is_null(struct reftable_iterator *it)
-{
-	return !it->ops;
-}
-
 static void filtering_ref_iterator_close(void *iter_arg)
 {
 	struct filtering_ref_iterator *fri = iter_arg;

reftable/iter.h

@@ -16,10 +16,6 @@ https://developers.google.com/open-source/licenses/bsd
 #include "reftable-iterator.h"
 #include "reftable-generic.h"
 
-/* Returns true for a zeroed out iterator, such as the one returned from
- * iterator_destroy. */
-int iterator_is_null(struct reftable_iterator *it);
-
 /* iterator that produces only ref records that point to `oid` */
 struct filtering_ref_iterator {
 	int double_check;

reftable/merged.c

@@ -17,23 +17,37 @@ https://developers.google.com/open-source/licenses/bsd
 #include "reftable-error.h"
 #include "system.h"
 
+struct merged_subiter {
+	struct reftable_iterator iter;
+	struct reftable_record rec;
+};
+
+struct merged_iter {
+	struct merged_subiter *subiters;
+	struct merged_iter_pqueue pq;
+	uint32_t hash_id;
+	size_t stack_len;
+	uint8_t typ;
+	int suppress_deletions;
+	ssize_t advance_index;
+};
+
 static int merged_iter_init(struct merged_iter *mi)
 {
 	for (size_t i = 0; i < mi->stack_len; i++) {
 		struct pq_entry e = {
 			.index = i,
+			.rec = &mi->subiters[i].rec,
 		};
 		int err;
 
-		reftable_record_init(&e.rec, mi->typ);
+		reftable_record_init(&mi->subiters[i].rec, mi->typ);
-		err = iterator_next(&mi->stack[i], &e.rec);
+		err = iterator_next(&mi->subiters[i].iter,
+				    &mi->subiters[i].rec);
 		if (err < 0)
 			return err;
-		if (err > 0) {
+		if (err > 0)
-			reftable_iterator_destroy(&mi->stack[i]);
-			reftable_record_release(&e.rec);
 			continue;
-		}
 
 		merged_iter_pqueue_add(&mi->pq, &e);
 	}
@@ -46,54 +60,66 @@ static void merged_iter_close(void *p)
 	struct merged_iter *mi = p;
 
 	merged_iter_pqueue_release(&mi->pq);
-	for (size_t i = 0; i < mi->stack_len; i++)
+	for (size_t i = 0; i < mi->stack_len; i++) {
-		reftable_iterator_destroy(&mi->stack[i]);
+		reftable_iterator_destroy(&mi->subiters[i].iter);
-	reftable_free(mi->stack);
+		reftable_record_release(&mi->subiters[i].rec);
-}
-
-static int merged_iter_advance_nonnull_subiter(struct merged_iter *mi,
-					       size_t idx)
-{
-	struct pq_entry e = {
-		.index = idx,
-	};
-	int err;
-
-	reftable_record_init(&e.rec, mi->typ);
-	err = iterator_next(&mi->stack[idx], &e.rec);
-	if (err < 0)
-		return err;
-
-	if (err > 0) {
-		reftable_iterator_destroy(&mi->stack[idx]);
-		reftable_record_release(&e.rec);
-		return 0;
 	}
-
+	reftable_free(mi->subiters);
-	merged_iter_pqueue_add(&mi->pq, &e);
-	return 0;
 }
 
 static int merged_iter_advance_subiter(struct merged_iter *mi, size_t idx)
 {
-	if (iterator_is_null(&mi->stack[idx]))
+	struct pq_entry e = {
-		return 0;
+		.index = idx,
-	return merged_iter_advance_nonnull_subiter(mi, idx);
+		.rec = &mi->subiters[idx].rec,
+	};
+	int err;
+
+	err = iterator_next(&mi->subiters[idx].iter, &mi->subiters[idx].rec);
+	if (err)
+		return err;
+
+	merged_iter_pqueue_add(&mi->pq, &e);
+	return 0;
 }
 
 static int merged_iter_next_entry(struct merged_iter *mi,
 				  struct reftable_record *rec)
 {
 	struct pq_entry entry = { 0 };
-	int err = 0;
+	int err = 0, empty;
 
-	if (merged_iter_pqueue_is_empty(mi->pq))
+	empty = merged_iter_pqueue_is_empty(mi->pq);
+
+	if (mi->advance_index >= 0) {
+		/*
+		 * When there are no pqueue entries then we only have a single
+		 * subiter left. There is no need to use the pqueue in that
+		 * case anymore as we know that the subiter will return entries
+		 * in the correct order already.
+		 *
+		 * While this may sound like a very specific edge case, it may
+		 * happen more frequently than you think. Most repositories
+		 * will end up having a single large base table that contains
+		 * most of the refs. It's thus likely that we exhaust all
+		 * subiters but the one from that base ref.
+		 */
+		if (empty)
+			return iterator_next(&mi->subiters[mi->advance_index].iter,
+					     rec);
+
+		err = merged_iter_advance_subiter(mi, mi->advance_index);
+		if (err < 0)
+			return err;
+		if (!err)
+			empty = 0;
+		mi->advance_index = -1;
+	}
+
+	if (empty)
 		return 1;
 
 	entry = merged_iter_pqueue_remove(&mi->pq);
-	err = merged_iter_advance_subiter(mi, entry.index);
-	if (err < 0)
-		return err;
 
 	/*
 	  One can also use reftable as datacenter-local storage, where the ref
@@ -107,54 +133,32 @@ static int merged_iter_next_entry(struct merged_iter *mi,
 		struct pq_entry top = merged_iter_pqueue_top(mi->pq);
 		int cmp;
 
-		/*
+		cmp = reftable_record_cmp(top.rec, entry.rec);
-		 * When the next entry comes from the same queue as the current
-		 * entry then it must by definition be larger. This avoids a
-		 * comparison in the most common case.
-		 */
-		if (top.index == entry.index)
-			break;
-
-		cmp = reftable_record_cmp(&top.rec, &entry.rec);
 		if (cmp > 0)
 			break;
 
 		merged_iter_pqueue_remove(&mi->pq);
 		err = merged_iter_advance_subiter(mi, top.index);
 		if (err < 0)
-			goto done;
+			return err;
-		reftable_record_release(&top.rec);
 	}
 
-	reftable_record_release(rec);
+	mi->advance_index = entry.index;
-	*rec = entry.rec;
+	SWAP(*rec, *entry.rec);
-
+	return 0;
-done:
-	if (err)
-		reftable_record_release(&entry.rec);
-	return err;
-}
-
-static int merged_iter_next(struct merged_iter *mi, struct reftable_record *rec)
-{
-	while (1) {
-		int err = merged_iter_next_entry(mi, rec);
-		if (err == 0 && mi->suppress_deletions &&
-		    reftable_record_is_deletion(rec)) {
-			continue;
-		}
-
-		return err;
-	}
 }
 
 static int merged_iter_next_void(void *p, struct reftable_record *rec)
 {
 	struct merged_iter *mi = p;
-	if (merged_iter_pqueue_is_empty(mi->pq))
+	while (1) {
-		return 1;
+		int err = merged_iter_next_entry(mi, rec);
-
+		if (err)
-	return merged_iter_next(mi, rec);
+			return err;
+		if (mi->suppress_deletions && reftable_record_is_deletion(rec))
+			continue;
+		return 0;
+	}
 }
 
 static struct reftable_iterator_vtable merged_iter_vtable = {
@@ -246,14 +250,15 @@ static int merged_table_seek_record(struct reftable_merged_table *mt,
 		.typ = reftable_record_type(rec),
 		.hash_id = mt->hash_id,
 		.suppress_deletions = mt->suppress_deletions,
+		.advance_index = -1,
 	};
 	struct merged_iter *p;
 	int err;
 
-	REFTABLE_CALLOC_ARRAY(merged.stack, mt->stack_len);
+	REFTABLE_CALLOC_ARRAY(merged.subiters, mt->stack_len);
 	for (size_t i = 0; i < mt->stack_len; i++) {
 		err = reftable_table_seek_record(&mt->stack[i],
-						 &merged.stack[merged.stack_len], rec);
+						 &merged.subiters[merged.stack_len].iter, rec);
 		if (err < 0)
 			goto out;
 		if (!err)

reftable/merged.h

@@ -9,7 +9,7 @@ https://developers.google.com/open-source/licenses/bsd
 #ifndef MERGED_H
 #define MERGED_H
 
-#include "pq.h"
+#include "system.h"
 
 struct reftable_merged_table {
 	struct reftable_table *stack;
@@ -24,15 +24,6 @@ struct reftable_merged_table {
 	uint64_t max;
 };
 
-struct merged_iter {
-	struct reftable_iterator *stack;
-	uint32_t hash_id;
-	size_t stack_len;
-	uint8_t typ;
-	int suppress_deletions;
-	struct merged_iter_pqueue pq;
-};
-
 void merged_table_release(struct reftable_merged_table *mt);
 
 #endif

reftable/pq.c

@@ -14,22 +14,12 @@ https://developers.google.com/open-source/licenses/bsd
 
 int pq_less(struct pq_entry *a, struct pq_entry *b)
 {
-	int cmp = reftable_record_cmp(&a->rec, &b->rec);
+	int cmp = reftable_record_cmp(a->rec, b->rec);
 	if (cmp == 0)
 		return a->index > b->index;
 	return cmp < 0;
 }
 
-struct pq_entry merged_iter_pqueue_top(struct merged_iter_pqueue pq)
-{
-	return pq.heap[0];
-}
-
-int merged_iter_pqueue_is_empty(struct merged_iter_pqueue pq)
-{
-	return pq.len == 0;
-}
-
 struct pq_entry merged_iter_pqueue_remove(struct merged_iter_pqueue *pq)
 {
 	int i = 0;
@@ -82,10 +72,6 @@ void merged_iter_pqueue_add(struct merged_iter_pqueue *pq, const struct pq_entry
 
 void merged_iter_pqueue_release(struct merged_iter_pqueue *pq)
 {
-	int i = 0;
-	for (i = 0; i < pq->len; i++) {
-		reftable_record_release(&pq->heap[i].rec);
-	}
 	FREE_AND_NULL(pq->heap);
-	pq->len = pq->cap = 0;
+	memset(pq, 0, sizeof(*pq));
 }

reftable/pq.h

@@ -12,8 +12,8 @@ https://developers.google.com/open-source/licenses/bsd
 #include "record.h"
 
 struct pq_entry {
-	int index;
+	size_t index;
-	struct reftable_record rec;
+	struct reftable_record *rec;
 };
 
 struct merged_iter_pqueue {
@@ -22,12 +22,20 @@ struct merged_iter_pqueue {
 	size_t cap;
 };
 
-struct pq_entry merged_iter_pqueue_top(struct merged_iter_pqueue pq);
-int merged_iter_pqueue_is_empty(struct merged_iter_pqueue pq);
 void merged_iter_pqueue_check(struct merged_iter_pqueue pq);
 struct pq_entry merged_iter_pqueue_remove(struct merged_iter_pqueue *pq);
 void merged_iter_pqueue_add(struct merged_iter_pqueue *pq, const struct pq_entry *e);
 void merged_iter_pqueue_release(struct merged_iter_pqueue *pq);
 int pq_less(struct pq_entry *a, struct pq_entry *b);
 
+static inline struct pq_entry merged_iter_pqueue_top(struct merged_iter_pqueue pq)
+{
+	return pq.heap[0];
+}
+
+static inline int merged_iter_pqueue_is_empty(struct merged_iter_pqueue pq)
+{
+	return pq.len == 0;
+}
+
 #endif

reftable/pq_test.c

@@ -27,48 +27,43 @@ void merged_iter_pqueue_check(struct merged_iter_pqueue pq)
 
 static void test_pq(void)
 {
-	char *names[54] = { NULL };
-	int N = ARRAY_SIZE(names) - 1;
-
 	struct merged_iter_pqueue pq = { NULL };
+	struct reftable_record recs[54];
+	int N = ARRAY_SIZE(recs) - 1, i;
 	char *last = NULL;
 
-	int i = 0;
 	for (i = 0; i < N; i++) {
-		char name[100];
+		struct strbuf refname = STRBUF_INIT;
-		snprintf(name, sizeof(name), "%02d", i);
+		strbuf_addf(&refname, "%02d", i);
-		names[i] = xstrdup(name);
+
+		reftable_record_init(&recs[i], BLOCK_TYPE_REF);
+		recs[i].u.ref.refname = strbuf_detach(&refname, NULL);
 	}
 
 	i = 1;
 	do {
-		struct pq_entry e = { .rec = { .type = BLOCK_TYPE_REF,
+		struct pq_entry e = {
-					       .u.ref = {
+			.rec = &recs[i],
-						       .refname = names[i],
+		};
-					       } } };
+
 		merged_iter_pqueue_add(&pq, &e);
 		merged_iter_pqueue_check(pq);
+
 		i = (i * 7) % N;
 	} while (i != 1);
 
 	while (!merged_iter_pqueue_is_empty(pq)) {
 		struct pq_entry e = merged_iter_pqueue_remove(&pq);
-		struct reftable_record *rec = &e.rec;
 		merged_iter_pqueue_check(pq);
 
-		EXPECT(reftable_record_type(rec) == BLOCK_TYPE_REF);
+		EXPECT(reftable_record_type(e.rec) == BLOCK_TYPE_REF);
-		if (last) {
+		if (last)
-			EXPECT(strcmp(last, rec->u.ref.refname) < 0);
+			EXPECT(strcmp(last, e.rec->u.ref.refname) < 0);
-		}
+		last = e.rec->u.ref.refname;
-		/* this is names[i], so don't dealloc. */
-		last = rec->u.ref.refname;
-		rec->u.ref.refname = NULL;
-		reftable_record_release(rec);
-	}
-	for (i = 0; i < N; i++) {
-		reftable_free(names[i]);
 	}
 
+	for (i = 0; i < N; i++)
+		reftable_record_release(&recs[i]);
 	merged_iter_pqueue_release(&pq);
 }
 

reftable/record.c

@@ -159,20 +159,19 @@ int reftable_encode_key(int *restart, struct string_view dest,
 	return start.len - dest.len;
 }
 
-int reftable_decode_key(struct strbuf *key, uint8_t *extra,
+int reftable_decode_key(struct strbuf *last_key, uint8_t *extra,
-			struct strbuf last_key, struct string_view in)
+			struct string_view in)
 {
 	int start_len = in.len;
 	uint64_t prefix_len = 0;
 	uint64_t suffix_len = 0;
-	int n = get_var_int(&prefix_len, &in);
+	int n;
+
+	n = get_var_int(&prefix_len, &in);
 	if (n < 0)
 		return -1;
 	string_view_consume(&in, n);
 
-	if (prefix_len > last_key.len)
-		return -1;
-
 	n = get_var_int(&suffix_len, &in);
 	if (n <= 0)
 		return -1;
@@ -181,12 +180,12 @@ int reftable_decode_key(struct strbuf *key, uint8_t *extra,
 	*extra = (uint8_t)(suffix_len & 0x7);
 	suffix_len >>= 3;
 
-	if (in.len < suffix_len)
+	if (in.len < suffix_len ||
+	    prefix_len > last_key->len)
 		return -1;
 
-	strbuf_reset(key);
+	strbuf_setlen(last_key, prefix_len);
-	strbuf_add(key, last_key.buf, prefix_len);
+	strbuf_add(last_key, in.buf, suffix_len);
-	strbuf_add(key, in.buf, suffix_len);
 	string_view_consume(&in, suffix_len);
 
 	return start_len - in.len;
@@ -205,14 +204,26 @@ static void reftable_ref_record_copy_from(void *rec, const void *src_rec,
 {
 	struct reftable_ref_record *ref = rec;
 	const struct reftable_ref_record *src = src_rec;
+	char *refname = NULL;
+	size_t refname_cap = 0;
+
 	assert(hash_size > 0);
 
-	/* This is simple and correct, but we could probably reuse the hash
+	SWAP(refname, ref->refname);
-	 * fields. */
+	SWAP(refname_cap, ref->refname_cap);
 	reftable_ref_record_release(ref);
+	SWAP(ref->refname, refname);
+	SWAP(ref->refname_cap, refname_cap);
+
 	if (src->refname) {
-		ref->refname = xstrdup(src->refname);
+		size_t refname_len = strlen(src->refname);
+
+		REFTABLE_ALLOC_GROW(ref->refname, refname_len + 1,
+				    ref->refname_cap);
+		memcpy(ref->refname, src->refname, refname_len);
+		ref->refname[refname_len] = 0;
 	}
+
 	ref->update_index = src->update_index;
 	ref->value_type = src->value_type;
 	switch (src->value_type) {
@@ -368,16 +379,24 @@ static int reftable_ref_record_decode(void *rec, struct strbuf key,
 	struct reftable_ref_record *r = rec;
 	struct string_view start = in;
 	uint64_t update_index = 0;
-	int n = get_var_int(&update_index, &in);
+	const char *refname = NULL;
+	size_t refname_cap = 0;
+	int n;
+
+	assert(hash_size > 0);
+
+	n = get_var_int(&update_index, &in);
 	if (n < 0)
 		return n;
 	string_view_consume(&in, n);
 
+	SWAP(refname, r->refname);
+	SWAP(refname_cap, r->refname_cap);
 	reftable_ref_record_release(r);
+	SWAP(r->refname, refname);
+	SWAP(r->refname_cap, refname_cap);
 
-	assert(hash_size > 0);
+	REFTABLE_ALLOC_GROW(r->refname, key.len + 1, r->refname_cap);
-
-	r->refname = reftable_malloc(key.len + 1);
 	memcpy(r->refname, key.buf, key.len);
 	r->refname[key.len] = 0;
 
@@ -1157,11 +1176,6 @@ void reftable_record_key(struct reftable_record *rec, struct strbuf *dest)
 	reftable_record_vtable(rec)->key(reftable_record_data(rec), dest);
 }
 
-uint8_t reftable_record_type(struct reftable_record *rec)
-{
-	return rec->type;
-}
-
 int reftable_record_encode(struct reftable_record *rec, struct string_view dest,
 			   int hash_size)
 {
@@ -1283,12 +1297,6 @@ int reftable_log_record_is_deletion(const struct reftable_log_record *log)
 	return (log->value_type == REFTABLE_LOG_DELETION);
 }
 
-void string_view_consume(struct string_view *s, int n)
-{
-	s->buf += n;
-	s->len -= n;
-}
-
 static void *reftable_record_data(struct reftable_record *rec)
 {
 	switch (rec->type) {

reftable/record.h

@@ -25,7 +25,11 @@ struct string_view {
 };
 
 /* Advance `s.buf` by `n`, and decrease length. */
-void string_view_consume(struct string_view *s, int n);
+static inline void string_view_consume(struct string_view *s, int n)
+{
+	s->buf += n;
+	s->len -= n;
+}
 
 /* utilities for de/encoding varints */
 
@@ -81,9 +85,12 @@ int reftable_encode_key(int *is_restart, struct string_view dest,
 			struct strbuf prev_key, struct strbuf key,
 			uint8_t extra);
 
-/* Decode into `key` and `extra` from `in` */
+/*
-int reftable_decode_key(struct strbuf *key, uint8_t *extra,
+ * Decode into `last_key` and `extra` from `in`. `last_key` is expected to
-			struct strbuf last_key, struct string_view in);
+ * contain the decoded key of the preceding record, if any.
+ */
+int reftable_decode_key(struct strbuf *last_key, uint8_t *extra,
+			struct string_view in);
 
 /* reftable_index_record are used internally to speed up lookups. */
 struct reftable_index_record {
@@ -124,7 +131,6 @@ int reftable_record_cmp(struct reftable_record *a, struct reftable_record *b);
 int reftable_record_equal(struct reftable_record *a, struct reftable_record *b, int hash_size);
 void reftable_record_print(struct reftable_record *rec, int hash_size);
 void reftable_record_key(struct reftable_record *rec, struct strbuf *dest);
-uint8_t reftable_record_type(struct reftable_record *rec);
 void reftable_record_copy_from(struct reftable_record *rec,
 			       struct reftable_record *src, int hash_size);
 uint8_t reftable_record_val_type(struct reftable_record *rec);
@@ -135,6 +141,11 @@ int reftable_record_decode(struct reftable_record *rec, struct strbuf key,
 			   int hash_size);
 int reftable_record_is_deletion(struct reftable_record *rec);
 
+static inline uint8_t reftable_record_type(struct reftable_record *rec)
+{
+	return rec->type;
+}
+
 /* frees and zeroes out the embedded record */
 void reftable_record_release(struct reftable_record *rec);
 

reftable/record_test.c

@@ -295,7 +295,8 @@ static void test_key_roundtrip(void)
 	EXPECT(!restart);
 	EXPECT(n > 0);
 
-	m = reftable_decode_key(&roundtrip, &rt_extra, last_key, dest);
+	strbuf_addstr(&roundtrip, "refs/heads/master");
+	m = reftable_decode_key(&roundtrip, &rt_extra, dest);
 	EXPECT(n == m);
 	EXPECT(0 == strbuf_cmp(&key, &roundtrip));
 	EXPECT(rt_extra == extra);

reftable/reftable-record.h

@@ -22,6 +22,7 @@ https://developers.google.com/open-source/licenses/bsd
 /* reftable_ref_record holds a ref database entry target_value */
 struct reftable_ref_record {
 	char *refname; /* Name of the ref, malloced. */
+	size_t refname_cap;
 	uint64_t update_index; /* Logical timestamp at which this value is
 				* written */