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#The MIT License (MIT)
#Copyright (c) 2018 Microsoft Corporation
#Permission is hereby granted, free of charge, to any person obtaining a copy
#of this software and associated documentation files (the "Software"), to deal
#in the Software without restriction, including without limitation the rights
#to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
#copies of the Software, and to permit persons to whom the Software is
#furnished to do so, subject to the following conditions:
#The above copyright notice and this permission notice shall be included in all
#copies or substantial portions of the Software.
#THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
#IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
#FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
#AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
#LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
#OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
#SOFTWARE.
"""Internal class for session read/write unavailable retry policy implementation in the Azure Cosmos database service.
"""
import logging
from azure.cosmos.documents import _OperationType
logger = logging.getLogger(__name__)
logger.setLevel(logging.INFO)
log_formatter = logging.Formatter('%(levelname)s:%(message)s')
log_handler = logging.StreamHandler()
log_handler.setFormatter(log_formatter)
logger.addHandler(log_handler)
class _SessionRetryPolicy(object):
"""The session retry policy used to handle read/write session unavailability.
"""
Max_retry_attempt_count = 1
Retry_after_in_milliseconds = 0
def __init__(self, endpoint_discovery_enable, global_endpoint_manager, *args):
self.global_endpoint_manager = global_endpoint_manager
self._max_retry_attempt_count = _SessionRetryPolicy.Max_retry_attempt_count
self.session_token_retry_count = 0
self.retry_after_in_milliseconds = _SessionRetryPolicy.Retry_after_in_milliseconds
self.endpoint_discovery_enable = endpoint_discovery_enable
self.request = args[0] if args else None
if self.request:
self.can_use_multiple_write_locations = self.global_endpoint_manager.can_use_multiple_write_locations(self.request)
# clear previous location-based routing directive
self.request.clear_route_to_location()
# Resolve the endpoint for the request and pin the resolution to the resolved endpoint
# This enables marking the endpoint unavailability on endpoint failover/unreachability
self.location_endpoint = self.global_endpoint_manager.resolve_service_endpoint(self.request)
self.request.route_to_location(self.location_endpoint)
def ShouldRetry(self, exception):
"""Returns true if should retry based on the passed-in exception.
:param (errors.HTTPFailure instance) exception:
:rtype:
boolean
"""
self.session_token_retry_count += 1
# clear previous location-based routing directive
self.request.clear_route_to_location()
if not self.endpoint_discovery_enable:
# if endpoint discovery is disabled, the request cannot be retried anywhere else
return False
else:
if self.can_use_multiple_write_locations:
if _OperationType.IsReadOnlyOperation(self.request.operation_type):
endpoints = self.global_endpoint_manager.get_ordered_read_endpoints()
else:
endpoints = self.global_endpoint_manager.get_ordered_write_endpoints()
if self.session_token_retry_count > len(endpoints):
# When use multiple write locations is true and the request has been tried
# on all locations, then don't retry the request
return False
else:
# set location-based routing directive based on request retry context
self.request.route_to_location_with_preferred_location_flag(self.session_token_retry_count - 1, self.session_token_retry_count > self._max_retry_attempt_count)
self.request.should_clear_session_token_on_session_read_failure = self.session_token_retry_count == len(endpoints) # clear on last attempt
# Resolve the endpoint for the request and pin the resolution to the resolved endpoint
# This enables marking the endpoint unavailability on endpoint failover/unreachability
self.location_endpoint = self.global_endpoint_manager.resolve_service_endpoint(self.request)
self.request.route_to_location(self.location_endpoint)
return True
else:
if self.session_token_retry_count > self._max_retry_attempt_count:
# When cannot use multiple write locations, then don't retry the request if
# we have already tried this request on the write location
return False
else:
# set location-based routing directive based on request retry context
self.request.route_to_location_with_preferred_location_flag(self.session_token_retry_count - 1, False)
self.request.should_clear_session_token_on_session_read_failure = True
# Resolve the endpoint for the request and pin the resolution to the resolved endpoint
# This enables marking the endpoint unavailability on endpoint failover/unreachability
self.location_endpoint = self.global_endpoint_manager.resolve_service_endpoint(self.request)
self.request.route_to_location(self.location_endpoint)
return True
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