From: Vladimír Čunát <vladimir.cunat@nic.cz>
Date: Fri, 1 Sep 2023 08:35:09 +0000 (+0200)
Subject: lib/cache/cdb_*: add API for iteration with MDB_DUPSORT
X-Git-Tag: v6.0.4~1^2~5
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c336c8bb285a54f6a382cc471c68c746f49c8a45;p=thirdparty%2Fknot-resolver.git

lib/cache/cdb_*: add API for iteration with MDB_DUPSORT
---

diff --git a/lib/cache/cdb_api.h b/lib/cache/cdb_api.h
index 41130b621..bce8740f7 100644
--- a/lib/cache/cdb_api.h
+++ b/lib/cache/cdb_api.h
@@ -106,4 +106,15 @@ struct kr_cdb_api {
 	 * and reopens it if it isn't; it errors out if the file doesn't exist anymore.
 	 * \return 0 if OK, 1 if reopened OK, < 0 kr_error */
 	int (*check_health)(kr_cdb_pt db, struct kr_cdb_stats *stat);
+
+
+	/** Start iterating; return the first *val with *key.
+	 *
+	 * This only makes sense if !is_cache.
+	 * TODO: it only works inside RO transactions for now.
+	 */
+	int (*it_first)(kr_cdb_pt db, struct kr_cdb_stats *stat,
+			const knot_db_val_t *key, knot_db_val_t *val);
+	/** Advance to the next *val with the same key. */
+	int (*it_next)(kr_cdb_pt db, struct kr_cdb_stats *stat, knot_db_val_t *val);
 };
diff --git a/lib/cache/cdb_lmdb.c b/lib/cache/cdb_lmdb.c
index 96cc2cd0e..5351cd737 100644
--- a/lib/cache/cdb_lmdb.c
+++ b/lib/cache/cdb_lmdb.c
@@ -244,7 +244,8 @@ static int cdb_commit(kr_cdb_pt db, struct kr_cdb_stats *stats, bool accept)
 	return ret;
 }
 
-/** Obtain a read-only cursor (and a read-only transaction). */
+/** Obtain a read-only cursor (and a read-only transaction).
+ * TODO: allow RW transaction (for ruledb iterator) */
 static int txn_curs_get(struct lmdb_env *env, MDB_cursor **curs, struct kr_cdb_stats *stats)
 {
 	if (kr_fails_assert(env && curs))
@@ -907,6 +908,47 @@ knot_db_t *kr_cdb_pt2knot_db_t(kr_cdb_pt db)
 	return libknot_db;
 }
 
+static int cdb_it_first(kr_cdb_pt db, struct kr_cdb_stats *stats,
+			const knot_db_val_t *key, knot_db_val_t *val)
+{
+	if (kr_fails_assert(db && key && key->data && val))
+		return kr_error(EINVAL);
+	struct lmdb_env *env = db2env(db);
+	if (kr_fails_assert(!env->is_cache))
+		return kr_error(EINVAL);
+
+	MDB_cursor *curs = NULL;
+	int ret = txn_curs_get(env, &curs, stats);
+	if (ret) return ret;
+
+	MDB_val key2_m = val_knot2mdb(*key);
+	MDB_val val2_m = { 0, NULL };
+	ret = mdb_cursor_get(curs, &key2_m, &val2_m, MDB_SET);
+	if (ret) return lmdb_error(env, ret);
+	ret = mdb_cursor_get(curs, &key2_m, &val2_m, MDB_FIRST_DUP);
+	if (ret) return lmdb_error(env, ret);
+	*val = val_mdb2knot(val2_m);
+	return kr_ok();
+}
+static int cdb_it_next(kr_cdb_pt db, struct kr_cdb_stats *stats, knot_db_val_t *val)
+{
+	if (kr_fails_assert(db && val))
+		return kr_error(EINVAL);
+	struct lmdb_env *env = db2env(db);
+	if (kr_fails_assert(!env->is_cache && env->txn.ro_curs_active))
+		return kr_error(EINVAL);
+
+	MDB_cursor *curs = NULL;
+	int ret = txn_curs_get(env, &curs, stats);
+	if (ret) return ret;
+	MDB_val val2_m = { 0, NULL };
+	ret = mdb_cursor_get(curs, NULL, &val2_m, MDB_NEXT_DUP);
+	if (ret) return lmdb_error(env, ret);
+	*val = val_mdb2knot(val2_m);
+	return kr_ok();
+}
+
+
 const struct kr_cdb_api *kr_cdb_lmdb(void)
 {
 	static const struct kr_cdb_api api = {
@@ -917,6 +959,7 @@ const struct kr_cdb_api *kr_cdb_lmdb(void)
 		cdb_read_leq, cdb_read_less,
 		cdb_usage_percent, cdb_get_maxsize,
 		cdb_check_health,
+		cdb_it_first, cdb_it_next,
 	};
 	return &api;
 }