iproto: support feature discovery

Since version 2.10.0 Tarantool supports feature discovery [1]. Client
can send the schema version and supported features and receive
server-side schema version and supported features information to tune
its behavior.

After this patch, the request would be send on `connect`. Connector will
use protocol version that is minimal of connector version (now it's 3)
and server version. Feature would be enabled if both client and server
supports it (for now client does not support any features from the
list). Unknown request type error response is expected for pre-2.10.0
versions. In this case, protocol version would be `None` and no features
would be enabled.

1. tarantool/tarantool#6253

Closes #206

Author: DifferentialOrange

Diff for: CHANGELOG.md

@@ -134,6 +134,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
     datetime: Timestamp('2022-03-31 00:00:00'), tz: ""
     ```
 
+- Support iproto feature discovery (#206).
+
 ### Changed
 - Bump msgpack requirement to 1.0.4 (PR #223).
   The only reason of this bump is various vulnerability fixes,

Diff for: tarantool/connection.py

@@ -37,7 +37,8 @@
     RequestUpdate,
     RequestUpsert,
     RequestAuthenticate,
-    RequestExecute
+    RequestExecute,
+    RequestProtocolVersion,
 )
 from tarantool.space import Space
 from tarantool.const import (
@@ -55,7 +56,14 @@
     REQUEST_TYPE_ERROR,
     IPROTO_GREETING_SIZE,
     ITERATOR_EQ,
-    ITERATOR_ALL
+    ITERATOR_ALL,
+    CONNECTOR_IPROTO_VERSION,
+    CONNECTOR_FEATURES,
+    IPROTO_FEATURE_STREAMS,
+    IPROTO_FEATURE_TRANSACTIONS,
+    IPROTO_FEATURE_ERROR_EXTENSION,
+    IPROTO_FEATURE_WATCHERS,
+    IPROTO_FEATURE_GRACEFUL_SHUTDOWN,
 )
 from tarantool.error import (
     Error,
@@ -498,6 +506,15 @@ def __init__(self, host, port,
         self.ssl_cert_file = ssl_cert_file
         self.ssl_ca_file = ssl_ca_file
         self.ssl_ciphers = ssl_ciphers
+        self._protocol_version = None
+        self._features = {
+            IPROTO_FEATURE_STREAMS: False,
+            IPROTO_FEATURE_TRANSACTIONS: False,
+            IPROTO_FEATURE_ERROR_EXTENSION: False,
+            IPROTO_FEATURE_WATCHERS: False,
+            IPROTO_FEATURE_GRACEFUL_SHUTDOWN: False,
+        }
+
         if connect_now:
             self.connect()
 
@@ -686,6 +703,7 @@ def connect(self):
                 self.wrap_socket_ssl()
             self.handshake()
             self.load_schema()
+            self._check_features()
         except SslError as e:
             raise e
         except Exception as e:
@@ -1602,3 +1620,44 @@ def execute(self, query, params=None):
         request = RequestExecute(self, query, params)
         response = self._send_request(request)
         return response
+
+    def _check_features(self):
+        """
+        Execute an ID request: inform the server about the protocol
+        version and features connector support and get server-side
+        information about it.
+
+        After executing this request, the connector will choose a
+        protocol version and features supported both by connector and
+        server.
+
+        :raise: :exc:`~AssertionError`,
+            :exc:`~tarantool.error.DatabaseError`,
+            :exc:`~tarantool.error.SchemaError`,
+            :exc:`~tarantool.error.NetworkError`,
+            :exc:`~tarantool.error.SslError`
+        """
+
+        try:
+            request = RequestProtocolVersion(self,
+                                             CONNECTOR_IPROTO_VERSION,
+                                             CONNECTOR_FEATURES)
+            response = self._send_request(request)
+            server_protocol_version = response.protocol_version
+            server_features = response.features
+        except DatabaseError as exc:
+            ER_UNKNOWN_REQUEST_TYPE = 48
+            if exc.code == ER_UNKNOWN_REQUEST_TYPE:
+                server_protocol_version = None
+                server_features = []
+            else:
+                raise exc
+
+        if server_protocol_version is not None:
+            self._protocol_version = min(server_protocol_version,
+                                         CONNECTOR_IPROTO_VERSION)
+
+        # Intercept lists of features
+        features_list = [val for val in CONNECTOR_FEATURES if val in server_features]
+        for val in features_list:
+            self._features[val] = True

Diff for: tarantool/const.py

@@ -35,6 +35,9 @@
 IPROTO_SQL_INFO = 0x42
 IPROTO_SQL_INFO_ROW_COUNT = 0x00
 IPROTO_SQL_INFO_AUTOINCREMENT_IDS = 0x01
+#
+IPROTO_VERSION = 0x54
+IPROTO_FEATURES = 0x55
 
 IPROTO_GREETING_SIZE = 128
 IPROTO_BODY_MAX_LEN = 2147483648
@@ -54,6 +57,7 @@
 REQUEST_TYPE_PING = 0x40
 REQUEST_TYPE_JOIN = 0x41
 REQUEST_TYPE_SUBSCRIBE = 0x42
+REQUEST_TYPE_ID = 0x49
 REQUEST_TYPE_ERROR = 1 << 15
 
 SPACE_SCHEMA = 272
@@ -85,6 +89,12 @@
 ITERATOR_OVERLAPS = 10
 ITERATOR_NEIGHBOR = 11
 
+IPROTO_FEATURE_STREAMS = 0
+IPROTO_FEATURE_TRANSACTIONS = 1
+IPROTO_FEATURE_ERROR_EXTENSION = 2
+IPROTO_FEATURE_WATCHERS = 3
+IPROTO_FEATURE_GRACEFUL_SHUTDOWN = 4
+
 # Default value for connection timeout (seconds)
 CONNECTION_TIMEOUT = None
 # Default value for socket timeout (seconds)
@@ -113,3 +123,8 @@
 POOL_INSTANCE_RECONNECT_MAX_ATTEMPTS = 0
 # Default delay between attempts to reconnect (seconds)
 POOL_INSTANCE_RECONNECT_DELAY = 0
+
+# Tarantool 2.10 protocol version is 3
+CONNECTOR_IPROTO_VERSION = 3
+# List of connector-supported features
+CONNECTOR_FEATURES = []

Diff for: tarantool/request.py

@@ -33,6 +33,8 @@
     IPROTO_SCHEMA_ID,
     IPROTO_SQL_TEXT,
     IPROTO_SQL_BIND,
+    IPROTO_VERSION,
+    IPROTO_FEATURES,
     REQUEST_TYPE_OK,
     REQUEST_TYPE_PING,
     REQUEST_TYPE_SELECT,
@@ -47,9 +49,14 @@
     REQUEST_TYPE_EVAL,
     REQUEST_TYPE_AUTHENTICATE,
     REQUEST_TYPE_JOIN,
-    REQUEST_TYPE_SUBSCRIBE
+    REQUEST_TYPE_SUBSCRIBE,
+    REQUEST_TYPE_ID,
+)
+from tarantool.response import (
+    Response,
+    ResponseExecute,
+    ResponseProtocolVersion,
 )
-from tarantool.response import Response, ResponseExecute
 from tarantool.utils import (
     strxor,
 )
@@ -656,3 +663,31 @@ def __init__(self, conn, sql, args):
 
         self._body = request_body
         self.response_class = ResponseExecute
+
+class RequestProtocolVersion(Request):
+    """
+    Represents ID request: inform the server about the protocol
+    version and features connector support.
+    """
+
+    request_type = REQUEST_TYPE_ID
+
+    def __init__(self, conn, protocol_version, features):
+        """
+        :param conn: Request sender.
+        :type conn: :class:`~tarantool.Connection`
+
+        :param protocol_version: Connector protocol version.
+        :type protocol_version: :obj:`int`
+
+        :param features: List of supported features.
+        :type features: :obj:`list`
+        """
+
+        super(RequestProtocolVersion, self).__init__(conn)
+
+        request_body = self._dumps({IPROTO_VERSION: protocol_version,
+                                    IPROTO_FEATURES: features})
+
+        self._body = request_body
+        self.response_class = ResponseProtocolVersion

Diff for: tarantool/response.py

@@ -17,7 +17,9 @@
     REQUEST_TYPE_ERROR,
     IPROTO_SQL_INFO,
     IPROTO_SQL_INFO_ROW_COUNT,
-    IPROTO_SQL_INFO_AUTOINCREMENT_IDS
+    IPROTO_SQL_INFO_AUTOINCREMENT_IDS,
+    IPROTO_VERSION,
+    IPROTO_FEATURES,
 )
 from tarantool.error import (
     DatabaseError,
@@ -324,3 +326,35 @@ def affected_row_count(self):
             return None
 
         return info.get(IPROTO_SQL_INFO_ROW_COUNT)
+
+
+class ResponseProtocolVersion(Response):
+    """
+    Represents an ID request response: information about server protocol
+    version and features it supports.
+    """
+
+    @property
+    def protocol_version(self):
+        """
+        Server protocol version.
+
+        :rtype: :obj:`int` or :obj:`None`
+        """
+
+        if self._return_code != 0:
+            return None
+        return self._body.get(IPROTO_VERSION)
+
+    @property
+    def features(self):
+        """
+        Server supported features.
+
+        :rtype: :obj:`list`
+        """
+
+        if self._return_code != 0:
+            return []
+        return self._body.get(IPROTO_FEATURES)
+

Diff for: test/suites/lib/skip.py

@@ -28,14 +28,11 @@ def wrapper(self, *args, **kwargs):
 
             assert srv is not None
 
-            self.__class__.tnt_version = re.match(
-                r'[\d.]+', srv.admin('box.info.version')[0]
-            ).group()
+            self.__class__.tnt_version = srv.admin.tnt_version
 
-        tnt_version = pkg_resources.parse_version(self.tnt_version)
         support_version = pkg_resources.parse_version(REQUIRED_TNT_VERSION)
 
-        if tnt_version < support_version:
+        if self.tnt_version < support_version:
             self.skipTest('Tarantool %s %s' % (self.tnt_version, msg))
 
         if func.__name__ != 'setUp':

Diff for: test/suites/lib/tarantool_admin.py

@@ -1,5 +1,7 @@
 import socket
 import yaml
+import re
+import pkg_resources
 
 
 class TarantoolAdmin(object):
@@ -8,6 +10,7 @@ def __init__(self, host, port):
         self.port = port
         self.is_connected = False
         self.socket = None
+        self._tnt_version = None
 
     def connect(self):
         self.socket = socket.create_connection((self.host, self.port))
@@ -62,3 +65,16 @@ def execute(self, command):
                 break
 
         return yaml.safe_load(res)
+
+    @property
+    def tnt_version(self):
+        if self._tnt_version is not None:
+            return self._tnt_version
+
+        raw_version = re.match(
+            r'[\d.]+', self.execute('box.info.version')[0]
+        ).group()
+
+        self._tnt_version = pkg_resources.parse_version(raw_version)
+
+        return self._tnt_version

Diff for: test/suites/test_protocol.py

@@ -1,13 +1,36 @@
 import sys
+import pkg_resources
 import unittest
-from tarantool.utils import greeting_decode, version_id
 import uuid
 
+import tarantool
+from tarantool.utils import greeting_decode, version_id
+
+from .lib.tarantool_server import TarantoolServer
+
+from tarantool.const import (
+    IPROTO_FEATURE_STREAMS,
+    IPROTO_FEATURE_TRANSACTIONS,
+    IPROTO_FEATURE_ERROR_EXTENSION,
+    IPROTO_FEATURE_WATCHERS,
+    IPROTO_FEATURE_GRACEFUL_SHUTDOWN,
+)
+
 class TestSuite_Protocol(unittest.TestCase):
     @classmethod
     def setUpClass(self):
         print(' PROTOCOL '.center(70, '='), file=sys.stderr)
         print('-' * 70, file=sys.stderr)
+        self.srv = TarantoolServer()
+        self.srv.script = 'test/suites/box.lua'
+        self.srv.start()
+        self.con = tarantool.Connection(self.srv.host, self.srv.args['primary'])
+        self.adm = self.srv.admin
+
+    def setUp(self):
+        # prevent a remote tarantool from clean our session
+        if self.srv.is_started():
+            self.srv.touch_lock()
 
     def test_00_greeting_1_6(self):
         buf = "Tarantool 1.6.6                                                \n" + \
@@ -45,3 +68,28 @@ def test_03_greeting_1_6_7(self):
         self.assertEqual(greeting.uuid,
                          uuid.UUID('52dc2837-8001-48fe-bdce-c493c04599ce'))
         self.assertIsNotNone(greeting.salt)
+
+    def test_04_protocol(self):
+        # First Tarantool protocol version (1) was introduced between
+        # 2.10.0-beta1 and 2.10.0-beta2. Versions 2 and 3 were also
+        # introduced between 2.10.0-beta1 and 2.10.0-beta2. Version 4
+        # was introduced between 2.10.0-beta2 and 2.10.0-rc1 and reverted
+        # back to version 3 in the same version interval.
+        # Tarantool 2.10.3 still has version 3.
+        if self.adm.tnt_version >= pkg_resources.parse_version('2.10.0'):
+            self.assertTrue(self.con._protocol_version >= 3)
+        else:
+            self.assertIsNone(self.con._protocol_version)
+
+        self.assertEqual(self.con._features[IPROTO_FEATURE_STREAMS], False)
+        self.assertEqual(self.con._features[IPROTO_FEATURE_TRANSACTIONS], False)
+        self.assertEqual(self.con._features[IPROTO_FEATURE_ERROR_EXTENSION], False)
+        self.assertEqual(self.con._features[IPROTO_FEATURE_WATCHERS], False)
+        self.assertEqual(self.con._features[IPROTO_FEATURE_GRACEFUL_SHUTDOWN], False)
+
+    @classmethod
+    def tearDownClass(self):
+        self.con.close()
+        self.srv.stop()
+        self.srv.clean()
+