Merge pull request #361 from scylladb/dk/320-python-implementation-of-decouple-schema-fetch-queries-from-server-side-timeouts

Decouple schema fetch queries timeouts from server side timeouts

Author: dkropachev

cassandra/cluster.py

@@ -19,6 +19,7 @@
 from __future__ import absolute_import
 
 import atexit
+import datetime
 from binascii import hexlify
 from collections import defaultdict
 from collections.abc import Mapping
@@ -82,7 +83,7 @@
 from cassandra.marshal import int64_pack
 from cassandra.tablets import Tablet, Tablets
 from cassandra.timestamps import MonotonicTimestampGenerator
-from cassandra.util import _resolve_contact_points_to_string_map, Version
+from cassandra.util import _resolve_contact_points_to_string_map, Version, maybe_add_timeout_to_query
 
 from cassandra.datastax.insights.reporter import MonitorReporter
 from cassandra.datastax.insights.util import version_supports_insights
@@ -1033,6 +1034,12 @@ def default_retry_policy(self, policy):
     or to disable the shardaware port (advanced shardaware)
     """
 
+    metadata_request_timeout = datetime.timedelta(seconds=2)
+    """
+    Timeout for all queries used by driver it self.
+    Supported only by Scylla clusters.
+    """
+
     @property
     def schema_metadata_enabled(self):
         """
@@ -1148,7 +1155,9 @@ def __init__(self,
                  client_id=None,
                  cloud=None,
                  scylla_cloud=None,
-                 shard_aware_options=None):
+                 shard_aware_options=None,
+                 metadata_request_timeout=None,
+                 ):
         """
         ``executor_threads`` defines the number of threads in a pool for handling asynchronous tasks such as
         extablishing connection pools or refreshing metadata.
@@ -1240,6 +1249,8 @@ def __init__(self,
         self.no_compact = no_compact
 
         self.auth_provider = auth_provider
+        if metadata_request_timeout is not None:
+            self.metadata_request_timeout = metadata_request_timeout
 
         if load_balancing_policy is not None:
             if isinstance(load_balancing_policy, type):
@@ -3549,6 +3560,7 @@ class PeersQueryType(object):
     _is_shutdown = False
     _timeout = None
     _protocol_version = None
+    _metadata_request_timeout = None
 
     _schema_event_refresh_window = None
     _topology_event_refresh_window = None
@@ -3648,7 +3660,7 @@ def _reconnect_internal(self):
         (conn, _) = self._connect_host_in_lbp()
         if conn is not None:
             return conn
-        
+
         # Try to re-resolve hostnames as a fallback when all hosts are unreachable
         self._cluster._resolve_hostnames()
 
@@ -3693,7 +3705,10 @@ def _try_connect(self, host):
         # If sharding information is available, it's a ScyllaDB cluster, so do not use peers_v2 table.
         if connection.features.sharding_info is not None:
             self._uses_peers_v2 = False
-        
+
+        # Cassandra does not support "USING TIMEOUT"
+        self._metadata_request_timeout = None if connection.features.sharding_info is None \
+            else datetime.timedelta(seconds=self._cluster.control_connection_timeout)
         self._tablets_routing_v1 = connection.features.tablets_routing_v1
 
         # use weak references in both directions
@@ -3710,8 +3725,10 @@ def _try_connect(self, host):
 
             sel_peers = self._get_peers_query(self.PeersQueryType.PEERS, connection)
             sel_local = self._SELECT_LOCAL if self._token_meta_enabled else self._SELECT_LOCAL_NO_TOKENS
-            peers_query = QueryMessage(query=sel_peers, consistency_level=ConsistencyLevel.ONE)
-            local_query = QueryMessage(query=sel_local, consistency_level=ConsistencyLevel.ONE)
+            peers_query = QueryMessage(query=maybe_add_timeout_to_query(sel_peers, self._metadata_request_timeout),
+                                       consistency_level=ConsistencyLevel.ONE)
+            local_query = QueryMessage(query=maybe_add_timeout_to_query(sel_local, self._metadata_request_timeout),
+                                       consistency_level=ConsistencyLevel.ONE)
             (peers_success, peers_result), (local_success, local_result) = connection.wait_for_responses(
                 peers_query, local_query, timeout=self._timeout, fail_on_error=False)
 
@@ -3722,7 +3739,8 @@ def _try_connect(self, host):
                 # error with the peers v2 query, fallback to peers v1
                 self._uses_peers_v2 = False
                 sel_peers = self._get_peers_query(self.PeersQueryType.PEERS, connection)
-                peers_query = QueryMessage(query=sel_peers, consistency_level=ConsistencyLevel.ONE)
+                peers_query = QueryMessage(query=maybe_add_timeout_to_query(sel_peers, self._metadata_request_timeout),
+                                           consistency_level=ConsistencyLevel.ONE)
                 peers_result = connection.wait_for_response(
                     peers_query, timeout=self._timeout)
 
@@ -3830,7 +3848,12 @@ def _refresh_schema(self, connection, preloaded_results=None, schema_agreement_w
             log.debug("Skipping schema refresh due to lack of schema agreement")
             return False
 
-        self._cluster.metadata.refresh(connection, self._timeout, fetch_size=self._schema_meta_page_size, **kwargs)
+        self._cluster.metadata.refresh(
+            connection,
+            self._timeout,
+            fetch_size=self._schema_meta_page_size,
+            metadata_request_timeout=self._metadata_request_timeout,
+            **kwargs)
 
         return True
 
@@ -3861,8 +3884,10 @@ def _refresh_node_list_and_token_map(self, connection, preloaded_results=None,
             else:
                 log.debug("[control connection] Refreshing node list and token map")
                 sel_local = self._SELECT_LOCAL
-            peers_query = QueryMessage(query=sel_peers, consistency_level=cl)
-            local_query = QueryMessage(query=sel_local, consistency_level=cl)
+            peers_query = QueryMessage(query=maybe_add_timeout_to_query(sel_peers, self._metadata_request_timeout),
+                                       consistency_level=cl)
+            local_query = QueryMessage(query=maybe_add_timeout_to_query(sel_local, self._metadata_request_timeout),
+                                       consistency_level=cl)
             peers_result, local_result = connection.wait_for_responses(
                 peers_query, local_query, timeout=self._timeout)
 
@@ -3917,8 +3942,9 @@ def _refresh_node_list_and_token_map(self, connection, preloaded_results=None,
                         # local rpc_address has not been queried yet, try to fetch it
                         # separately, which might fail because C* < 2.1.6 doesn't have rpc_address
                         # in system.local. See CASSANDRA-9436.
-                        local_rpc_address_query = QueryMessage(query=self._SELECT_LOCAL_NO_TOKENS_RPC_ADDRESS,
-                                                               consistency_level=ConsistencyLevel.ONE)
+                        local_rpc_address_query = QueryMessage(
+                            query=maybe_add_timeout_to_query(self._SELECT_LOCAL_NO_TOKENS_RPC_ADDRESS, self._metadata_request_timeout),
+                            consistency_level=ConsistencyLevel.ONE)
                         success, local_rpc_address_result = connection.wait_for_response(
                             local_rpc_address_query, timeout=self._timeout, fail_on_error=False)
                         if success:
@@ -4153,8 +4179,10 @@ def wait_for_schema_agreement(self, connection=None, preloaded_results=None, wai
             select_peers_query = self._get_peers_query(self.PeersQueryType.PEERS_SCHEMA, connection)
 
             while elapsed < total_timeout:
-                peers_query = QueryMessage(query=select_peers_query, consistency_level=cl)
-                local_query = QueryMessage(query=self._SELECT_SCHEMA_LOCAL, consistency_level=cl)
+                peers_query = QueryMessage(query=maybe_add_timeout_to_query(select_peers_query, self._metadata_request_timeout),
+                                           consistency_level=cl)
+                local_query = QueryMessage(query=maybe_add_timeout_to_query(self._SELECT_SCHEMA_LOCAL, self._metadata_request_timeout),
+                                           consistency_level=cl)
                 try:
                     timeout = min(self._timeout, total_timeout - elapsed)
                     peers_result, local_result = connection.wait_for_responses(