reftable/merged: adapt interface to allow reuse of iterators

Refactor the interfaces exposed by `struct reftable_merged_table` and
`struct merged_iter` such that they support iterator reuse. This is done
by separating initialization of the iterator and seeking on it.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

reftable/merged.c

@@ -262,41 +262,6 @@ void merged_table_init_iter(struct reftable_merged_table *mt,
 	iterator_from_merged_iter(it, mi);
 }
 
-int reftable_merged_table_seek_ref(struct reftable_merged_table *mt,
-				   struct reftable_iterator *it,
-				   const char *name)
-{
-	struct reftable_record rec = {
-		.type = BLOCK_TYPE_REF,
-		.u.ref = {
-			.refname = (char *)name,
-		},
-	};
-	merged_table_init_iter(mt, it, BLOCK_TYPE_REF);
-	return iterator_seek(it, &rec);
-}
-
-int reftable_merged_table_seek_log_at(struct reftable_merged_table *mt,
-				      struct reftable_iterator *it,
-				      const char *name, uint64_t update_index)
-{
-	struct reftable_record rec = { .type = BLOCK_TYPE_LOG,
-				       .u.log = {
-					       .refname = (char *)name,
-					       .update_index = update_index,
-				       } };
-	merged_table_init_iter(mt, it, BLOCK_TYPE_LOG);
-	return iterator_seek(it, &rec);
-}
-
-int reftable_merged_table_seek_log(struct reftable_merged_table *mt,
-				   struct reftable_iterator *it,
-				   const char *name)
-{
-	uint64_t max = ~((uint64_t)0);
-	return reftable_merged_table_seek_log_at(mt, it, name, max);
-}
-
 uint32_t reftable_merged_table_hash_id(struct reftable_merged_table *mt)
 {
 	return mt->hash_id;

reftable/merged_test.c

@@ -12,6 +12,7 @@ license that can be found in the LICENSE file or at
 
 #include "basics.h"
 #include "blocksource.h"
+#include "constants.h"
 #include "reader.h"
 #include "record.h"
 #include "test_framework.h"
@@ -145,7 +146,10 @@ static void test_merged_between(void)
 	int i;
 	struct reftable_ref_record ref = { NULL };
 	struct reftable_iterator it = { NULL };
-	int err = reftable_merged_table_seek_ref(mt, &it, "a");
+	int err;
+
+	merged_table_init_iter(mt, &it, BLOCK_TYPE_REF);
+	err = reftable_iterator_seek_ref(&it, "a");
 	EXPECT_ERR(err);
 
 	err = reftable_iterator_next_ref(&it, &ref);
@@ -217,14 +221,15 @@ static void test_merged(void)
 	struct reftable_reader **readers = NULL;
 	struct reftable_merged_table *mt =
 		merged_table_from_records(refs, &bs, &readers, sizes, bufs, 3);
-
 	struct reftable_iterator it = { NULL };
-	int err = reftable_merged_table_seek_ref(mt, &it, "a");
+	int err;
 	struct reftable_ref_record *out = NULL;
 	size_t len = 0;
 	size_t cap = 0;
 	int i = 0;
 
+	merged_table_init_iter(mt, &it, BLOCK_TYPE_REF);
+	err = reftable_iterator_seek_ref(&it, "a");
 	EXPECT_ERR(err);
 	EXPECT(reftable_merged_table_hash_id(mt) == GIT_SHA1_FORMAT_ID);
 	EXPECT(reftable_merged_table_min_update_index(mt) == 1);
@@ -348,14 +353,15 @@ static void test_merged_logs(void)
 	struct reftable_reader **readers = NULL;
 	struct reftable_merged_table *mt = merged_table_from_log_records(
 		logs, &bs, &readers, sizes, bufs, 3);
-
 	struct reftable_iterator it = { NULL };
-	int err = reftable_merged_table_seek_log(mt, &it, "a");
+	int err;
 	struct reftable_log_record *out = NULL;
 	size_t len = 0;
 	size_t cap = 0;
 	int i = 0;
 
+	merged_table_init_iter(mt, &it, BLOCK_TYPE_LOG);
+	err = reftable_iterator_seek_log(&it, "a");
 	EXPECT_ERR(err);
 	EXPECT(reftable_merged_table_hash_id(mt) == GIT_SHA1_FORMAT_ID);
 	EXPECT(reftable_merged_table_min_update_index(mt) == 1);
@@ -377,7 +383,8 @@ static void test_merged_logs(void)
 						 GIT_SHA1_RAWSZ));
 	}
 
-	err = reftable_merged_table_seek_log_at(mt, &it, "a", 2);
+	merged_table_init_iter(mt, &it, BLOCK_TYPE_LOG);
+	err = reftable_iterator_seek_log_at(&it, "a", 2);
 	EXPECT_ERR(err);
 	reftable_log_record_release(&out[0]);
 	err = reftable_iterator_next_log(&it, &out[0]);

reftable/reftable-merged.h

@@ -36,21 +36,6 @@ int reftable_new_merged_table(struct reftable_merged_table **dest,
 			      struct reftable_table *stack, size_t n,
 			      uint32_t hash_id);
 
-/* returns an iterator positioned just before 'name' */
-int reftable_merged_table_seek_ref(struct reftable_merged_table *mt,
-				   struct reftable_iterator *it,
-				   const char *name);
-
-/* returns an iterator for log entry, at given update_index */
-int reftable_merged_table_seek_log_at(struct reftable_merged_table *mt,
-				      struct reftable_iterator *it,
-				      const char *name, uint64_t update_index);
-
-/* like reftable_merged_table_seek_log_at but look for the newest entry. */
-int reftable_merged_table_seek_log(struct reftable_merged_table *mt,
-				   struct reftable_iterator *it,
-				   const char *name);
-
 /* returns the max update_index covered by this merged table. */
 uint64_t
 reftable_merged_table_max_update_index(struct reftable_merged_table *mt);

reftable/stack.c

@@ -925,7 +925,8 @@ static int stack_write_compact(struct reftable_stack *st,
 		goto done;
 	}
 
-	err = reftable_merged_table_seek_ref(mt, &it, "");
+	merged_table_init_iter(mt, &it, BLOCK_TYPE_REF);
+	err = reftable_iterator_seek_ref(&it, "");
 	if (err < 0)
 		goto done;
 
@@ -949,7 +950,8 @@ static int stack_write_compact(struct reftable_stack *st,
 	}
 	reftable_iterator_destroy(&it);
 
-	err = reftable_merged_table_seek_log(mt, &it, "");
+	merged_table_init_iter(mt, &it, BLOCK_TYPE_LOG);
+	err = reftable_iterator_seek_log(&it, "");
 	if (err < 0)
 		goto done;
 
@@ -1340,9 +1342,11 @@ int reftable_stack_read_ref(struct reftable_stack *st, const char *refname,
 int reftable_stack_read_log(struct reftable_stack *st, const char *refname,
 			    struct reftable_log_record *log)
 {
-	struct reftable_iterator it = { NULL };
+	struct reftable_iterator it = {0};
-	struct reftable_merged_table *mt = reftable_stack_merged_table(st);
+	int err;
-	int err = reftable_merged_table_seek_log(mt, &it, refname);
+
+	reftable_stack_init_log_iterator(st, &it);
+	err = reftable_iterator_seek_log(&it, refname);
 	if (err)
 		goto done;