ovsdb: storage: Allow setting the name for the unbacked storage.

ovsdb_create() requires schema or storage to be nonnull, but in
practice it requires to have schema name or a storage name to
use it as a database name.  Only clustered storage has a name.
This means that only clustered database can be created without
schema,  Changing that by allowing unbacked storage to have a
name.  This way we can create database with unbacked storage
without schema.  Will be used in next commits to create database
for ovsdb 'relay' service model.

Acked-by: Mark D. Gray <mark.d.gray@redhat.com>
Acked-by: Dumitru Ceara <dceara@redhat.com>
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>

ovsdb/file.c

@@ -318,7 +318,7 @@ ovsdb_convert(const struct ovsdb *src, const struct ovsdb_schema *new_schema,
               struct ovsdb **dstp)
 {
     struct ovsdb *dst = ovsdb_create(ovsdb_schema_clone(new_schema),
-                                     ovsdb_storage_create_unbacked());
+                                     ovsdb_storage_create_unbacked(NULL));
     struct ovsdb_txn *txn = ovsdb_txn_create(dst);
     struct ovsdb_error *error = NULL;
 

ovsdb/ovsdb-server.c

@@ -736,7 +736,7 @@ add_server_db(struct server_config *config)
     /* We don't need txn_history for server_db. */
 
     db->filename = xstrdup("<internal>");
-    db->db = ovsdb_create(schema, ovsdb_storage_create_unbacked());
+    db->db = ovsdb_create(schema, ovsdb_storage_create_unbacked(NULL));
     bool ok OVS_UNUSED = ovsdb_jsonrpc_server_add_db(config->jsonrpc, db->db);
     ovs_assert(ok);
     add_db(config, db);

ovsdb/storage.c

@@ -45,6 +45,8 @@ struct ovsdb_storage {
     struct ovsdb_log *log;
     struct raft *raft;
 
+    char *unbacked_name; /* Name of the unbacked storage. */
+
     /* All kinds of storage. */
     struct ovsdb_error *error;  /* If nonnull, a permanent error. */
     long long next_snapshot_min; /* Earliest time to take next snapshot. */
@@ -121,12 +123,14 @@ ovsdb_storage_open_standalone(const char *filename, bool rw)
 }
 
 /* Creates and returns new storage without any backing.  Nothing will be read
- * from the storage, and writes are discarded. */
+ * from the storage, and writes are discarded.  If 'name' is nonnull, it will
+ * be used as a storage name. */
 struct ovsdb_storage *
-ovsdb_storage_create_unbacked(void)
+ovsdb_storage_create_unbacked(const char *name)
 {
     struct ovsdb_storage *storage = xzalloc(sizeof *storage);
     schedule_next_snapshot(storage, false);
+    storage->unbacked_name = nullable_xstrdup(name);
     return storage;
 }
 
@@ -137,6 +141,7 @@ ovsdb_storage_close(struct ovsdb_storage *storage)
         ovsdb_log_close(storage->log);
         raft_close(storage->raft);
         ovsdb_error_destroy(storage->error);
+        free(storage->unbacked_name);
         free(storage);
     }
 }
@@ -230,7 +235,9 @@ ovsdb_storage_wait(struct ovsdb_storage *storage)
 const char *
 ovsdb_storage_get_name(const struct ovsdb_storage *storage)
 {
-    return storage->raft ? raft_get_name(storage->raft) : NULL;
+    return storage->unbacked_name ? storage->unbacked_name
+           : storage->raft ? raft_get_name(storage->raft)
+           : NULL;
 }
 
 /* Attempts to read a log record from 'storage'.

ovsdb/storage.h

@@ -29,7 +29,7 @@ struct uuid;
 struct ovsdb_error *ovsdb_storage_open(const char *filename, bool rw,
                                        struct ovsdb_storage **)
     OVS_WARN_UNUSED_RESULT;
-struct ovsdb_storage *ovsdb_storage_create_unbacked(void);
+struct ovsdb_storage *ovsdb_storage_create_unbacked(const char *name);
 void ovsdb_storage_close(struct ovsdb_storage *);
 
 const char *ovsdb_storage_get_model(const struct ovsdb_storage *);

tests/test-ovsdb.c

@@ -1485,7 +1485,7 @@ do_execute__(struct ovs_cmdl_context *ctx, bool ro)
     json = parse_json(ctx->argv[1]);
     check_ovsdb_error(ovsdb_schema_from_json(json, &schema));
     json_destroy(json);
-    db = ovsdb_create(schema, ovsdb_storage_create_unbacked());
+    db = ovsdb_create(schema, ovsdb_storage_create_unbacked(NULL));
 
     for (i = 2; i < ctx->argc; i++) {
         struct json *params, *result;
@@ -1551,7 +1551,7 @@ do_trigger(struct ovs_cmdl_context *ctx)
     json = parse_json(ctx->argv[1]);
     check_ovsdb_error(ovsdb_schema_from_json(json, &schema));
     json_destroy(json);
-    db = ovsdb_create(schema, ovsdb_storage_create_unbacked());
+    db = ovsdb_create(schema, ovsdb_storage_create_unbacked(NULL));
 
     ovsdb_server_init(&server);
     ovsdb_server_add_db(&server, db);
@@ -1781,7 +1781,7 @@ do_transact(struct ovs_cmdl_context *ctx)
                       "       \"j\": {\"type\": \"integer\"}}}}}");
     check_ovsdb_error(ovsdb_schema_from_json(json, &schema));
     json_destroy(json);
-    do_transact_db = ovsdb_create(schema, ovsdb_storage_create_unbacked());
+    do_transact_db = ovsdb_create(schema, ovsdb_storage_create_unbacked(NULL));
     do_transact_table = ovsdb_get_table(do_transact_db, "mytable");
     ovs_assert(do_transact_table != NULL);