api: extend connect with fetch_schema param

Added support of the fetch_schema parameter,
which allows to ignore schema changes on the server.

Closes #219

Author: GRISHNOV

CHANGELOG.md

@@ -9,6 +9,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 - Support custom packer and unpacker factories (#191).
 
+- Support of the fetch_schema parameter for connection (#219).
+
 ### Changed
 
 ### Fixed

tarantool/connection.py

@@ -363,7 +363,8 @@ def __init__(self, host, port,
                  ssl_ca_file=DEFAULT_SSL_CA_FILE,
                  ssl_ciphers=DEFAULT_SSL_CIPHERS,
                  packer_factory=default_packer_factory,
-                 unpacker_factory=default_unpacker_factory):
+                 unpacker_factory=default_unpacker_factory,
+                 fetch_schema=True):
         """
         :param host: Server hostname or IP address. Use ``None`` for
             Unix sockets.
@@ -503,6 +504,17 @@ def __init__(self, host, port,
             callable[[:obj:`~tarantool.Connection`], :obj:`~msgpack.Unpacker`],
             optional
 
+        :param bool fetch_schema: If ``False``, allows to ignore schema
+            changes on the server, schema updates are not automatically
+            loaded. As a result, the methods become unavailable:
+            :meth:`~tarantool.Connection.replace`,
+            :meth:`~tarantool.Connection.insert`,
+            :meth:`~tarantool.Connection.delete`,
+            :meth:`~tarantool.Connection.upsert`,
+            :meth:`~tarantool.Connection.update`,
+            :meth:`~tarantool.Connection.select`.
+        :type fetch_schema: :obj:`bool`, optional
+
         :raise: :exc:`~tarantool.error.ConfigurationError`,
             :meth:`~tarantool.Connection.connect` exceptions
 
@@ -533,8 +545,10 @@ def __init__(self, host, port,
         self.socket_timeout = socket_timeout
         self.reconnect_delay = reconnect_delay
         self.reconnect_max_attempts = reconnect_max_attempts
-        self.schema = Schema(self)
-        self.schema_version = 1
+        self.fetch_schema = fetch_schema
+        if self.fetch_schema:
+            self.schema = Schema(self)
+            self.schema_version = 1
         self._socket = None
         self.connected = False
         self.error = True
@@ -745,7 +759,8 @@ def connect(self):
             if self.transport == SSL_TRANSPORT:
                 self.wrap_socket_ssl()
             self.handshake()
-            self.load_schema()
+            if self.fetch_schema:
+                self.load_schema()
             self._check_features()
         except SslError as e:
             raise e
@@ -841,7 +856,8 @@ def _send_request_wo_reconnect(self, request, on_push=None, on_push_ctx=None):
                 response = request.response_class(self, self._read_response())
                 break
             except SchemaReloadException as e:
-                self.update_schema(e.schema_version)
+                if self.fetch_schema:
+                    self.update_schema(e.schema_version)
                 continue
 
         while response._code == IPROTO_CHUNK:
@@ -1089,11 +1105,16 @@ def replace(self, space_name, values, on_push=None, on_push_ctx=None):
             :exc:`~tarantool.error.DatabaseError`,
             :exc:`~tarantool.error.SchemaError`,
             :exc:`~tarantool.error.NetworkError`,
-            :exc:`~tarantool.error.SslError`
+            :exc:`~tarantool.error.SslError`,
+            :exc:`~tarantool.error.NotSupportedError`
 
         .. _replace: https://www.tarantool.io/en/doc/latest/reference/reference_lua/box_space/replace/
         """
 
+        if not self.fetch_schema:
+            raise NotSupportedError('This method is not available in ' +
+                                    'connection opened with fetch_schema=False')
+
         if isinstance(space_name, str):
             space_name = self.schema.get_space(space_name).sid
         if on_push is not None and not callable(on_push):
@@ -1276,11 +1297,16 @@ def insert(self, space_name, values, on_push=None, on_push_ctx=None):
             :exc:`~tarantool.error.DatabaseError`,
             :exc:`~tarantool.error.SchemaError`,
             :exc:`~tarantool.error.NetworkError`,
-            :exc:`~tarantool.error.SslError`
+            :exc:`~tarantool.error.SslError`,
+            :exc:`~tarantool.error.NotSupportedError`
 
         .. _insert: https://www.tarantool.io/en/doc/latest/reference/reference_lua/box_space/insert/
         """
 
+        if not self.fetch_schema:
+            raise NotSupportedError('This method is not available in ' +
+                                    'connection opened with fetch_schema=False')
+
         if isinstance(space_name, str):
             space_name = self.schema.get_space(space_name).sid
         if on_push is not None and not callable(on_push):
@@ -1315,11 +1341,16 @@ def delete(self, space_name, key, *, index=0, on_push=None, on_push_ctx=None):
             :exc:`~tarantool.error.DatabaseError`,
             :exc:`~tarantool.error.SchemaError`,
             :exc:`~tarantool.error.NetworkError`,
-            :exc:`~tarantool.error.SslError`
+            :exc:`~tarantool.error.SslError`,
+            :exc:`~tarantool.error.NotSupportedError`
 
         .. _delete: https://www.tarantool.io/en/doc/latest/reference/reference_lua/box_space/delete/
         """
 
+        if not self.fetch_schema:
+            raise NotSupportedError('This method is not available in ' +
+                                    'connection opened with fetch_schema=False')
+
         key = wrap_key(key)
         if isinstance(space_name, str):
             space_name = self.schema.get_space(space_name).sid
@@ -1374,11 +1405,16 @@ def upsert(self, space_name, tuple_value, op_list, *, index=0, on_push=None, on_
             :exc:`~tarantool.error.DatabaseError`,
             :exc:`~tarantool.error.SchemaError`,
             :exc:`~tarantool.error.NetworkError`,
-            :exc:`~tarantool.error.SslError`
+            :exc:`~tarantool.error.SslError`,
+            :exc:`~tarantool.error.NotSupportedError`
 
         .. _upsert: https://www.tarantool.io/en/doc/latest/reference/reference_lua/box_space/upsert/
         """
 
+        if not self.fetch_schema:
+            raise NotSupportedError('This method is not available in ' +
+                                    'connection opened with fetch_schema=False')
+
         if isinstance(space_name, str):
             space_name = self.schema.get_space(space_name).sid
         if isinstance(index, str):
@@ -1462,11 +1498,16 @@ def update(self, space_name, key, op_list, *, index=0, on_push=None, on_push_ctx
             :exc:`~tarantool.error.DatabaseError`,
             :exc:`~tarantool.error.SchemaError`,
             :exc:`~tarantool.error.NetworkError`,
-            :exc:`~tarantool.error.SslError`
+            :exc:`~tarantool.error.SslError`,
+            :exc:`~tarantool.error.NotSupportedError`
 
         .. _update: https://www.tarantool.io/en/doc/latest/reference/reference_lua/box_space/update/
         """
 
+        if not self.fetch_schema:
+            raise NotSupportedError('This method is not available in ' +
+                                    'connection opened with fetch_schema=False')
+
         key = wrap_key(key)
         if isinstance(space_name, str):
             space_name = self.schema.get_space(space_name).sid
@@ -1648,11 +1689,16 @@ def select(self, space_name, key=None, *, offset=0, limit=0xffffffff, index=0, i
             :exc:`~tarantool.error.DatabaseError`,
             :exc:`~tarantool.error.SchemaError`,
             :exc:`~tarantool.error.NetworkError`,
-            :exc:`~tarantool.error.SslError`
+            :exc:`~tarantool.error.SslError`,
+            :exc:`~tarantool.error.NotSupportedError`
 
         .. _select: https://www.tarantool.io/en/doc/latest/reference/reference_lua/box_space/select/
         """
 
+        if not self.fetch_schema:
+            raise NotSupportedError('This method is not available in ' +
+                                    'connection opened with fetch_schema=False')
+
         if iterator is None:
             iterator = ITERATOR_EQ
             if key is None or (isinstance(key, (list, tuple)) and

tarantool/request.py

@@ -186,9 +186,13 @@ def header(self, length):
         """
 
         self._sync = self.conn.generate_sync()
-        header = self._dumps({IPROTO_REQUEST_TYPE: self.request_type,
-                              IPROTO_SYNC: self._sync,
-                              IPROTO_SCHEMA_ID: self.conn.schema_version})
+        header_fields = {
+            IPROTO_REQUEST_TYPE: self.request_type,
+            IPROTO_SYNC: self._sync,
+        }
+        if self.conn.fetch_schema:
+            header_fields[IPROTO_SCHEMA_ID] = self.conn.schema_version
+        header = self._dumps(header_fields)
 
         return self._dumps(length + len(header)) + header
 

test/suites/test_schema.py

@@ -2,6 +2,7 @@
 import unittest
 import tarantool
 from .lib.tarantool_server import TarantoolServer
+from tarantool.error import NotSupportedError
 
 
 # FIXME: I'm quite sure that there is a simpler way to count
@@ -43,6 +44,8 @@ def setUpClass(self):
         self.srv.start()
         self.con = tarantool.Connection(self.srv.host, self.srv.args['primary'],
                                         encoding=self.encoding)
+        self.con_schema_disable = tarantool.Connection(self.srv.host, self.srv.args['primary'],
+                                                       encoding=self.encoding, fetch_schema=False)
         self.sch = self.con.schema
 
         # The relevant test cases mainly target Python 2, where
@@ -341,9 +344,43 @@ def test_07_schema_version_update(self):
         self.srv.admin("box.schema.create_space('ttt22')")
         self.assertEqual(len(self.con.select('_space')), _space_len + 1)
 
+    def test_08_schema_fetch_disable(self):
+        self.assertEqual(hasattr(self.con_schema_disable, 'schema_version'), False)
+        self.assertEqual(hasattr(self.con_schema_disable, 'schema'), False)
+        
+        testing_methods = {
+            'replace': {
+                'input': ['',[]],
+            },
+            'insert': {
+                'input': ['',[]],
+            }, 
+            'delete': {
+                'input': ['',0],
+            },
+            'upsert': {
+                'input': ['',[],[]],
+            },
+            'update': {
+                'input': ['', 0, []],
+            }, 
+            'select': {
+                'input': [''],
+            },
+        }
+        for method_case in testing_methods.keys():
+            with self.subTest(name=method_case):
+                testing_function = getattr(self.con_schema_disable, method_case)
+                try:
+                    _ = testing_function(*testing_methods[method_case]['input'])
+                except NotSupportedError as e:
+                    self.assertEqual(e.message, 'This method is not available in ' + 
+                                                'connection opened with fetch_schema=False')
+
     @classmethod
     def tearDownClass(self):
         self.con.close()
+        self.con_schema_disable.close()
         self.srv.stop()
         self.srv.clean()