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#The MIT License (MIT)
#Copyright (c) 2014 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 proxy query execution context implementation in the Azure Cosmos database service.
"""
import json
from six.moves import xrange
from azure.cosmos.errors import HTTPFailure
from azure.cosmos.execution_context.base_execution_context import _QueryExecutionContextBase
from azure.cosmos.execution_context.base_execution_context import _DefaultQueryExecutionContext
from azure.cosmos.execution_context.query_execution_info import _PartitionedQueryExecutionInfo
from azure.cosmos.execution_context import endpoint_component
from azure.cosmos.execution_context import multi_execution_aggregator
from azure.cosmos.http_constants import StatusCodes, SubStatusCodes
class _ProxyQueryExecutionContext(_QueryExecutionContextBase):
'''
This class represents a proxy execution context wrapper:
- By default uses _DefaultQueryExecutionContext
- if backend responds a 400 error code with a Query Execution Info
it switches to _MultiExecutionContextAggregator
'''
def __init__(self, client, resource_link, query, options, fetch_function):
'''
Constructor
'''
super(_ProxyQueryExecutionContext, self).__init__(client, options)
self._execution_context = _DefaultQueryExecutionContext(client, options, fetch_function)
self._resource_link = resource_link
self._query = query
self._fetch_function = fetch_function
def next(self):
"""Returns the next query result.
:return:
The next query result.
:rtype: dict
:raises StopIteration: If no more result is left.
"""
try:
return next(self._execution_context)
except HTTPFailure as e:
if self._is_partitioned_execution_info(e):
query_execution_info = self._get_partitioned_execution_info(e)
self._execution_context = self._create_pipelined_execution_context(query_execution_info)
else:
raise e
return next(self._execution_context)
def fetch_next_block(self):
"""Returns a block of results.
This method only exists for backward compatibility reasons. (Because QueryIterable
has exposed fetch_next_block api).
:return:
List of results.
:rtype: list
"""
try:
return self._execution_context.fetch_next_block()
except HTTPFailure as e:
if self._is_partitioned_execution_info(e):
query_execution_info = self._get_partitioned_execution_info(e)
self._execution_context = self._create_pipelined_execution_context(query_execution_info)
else:
raise e
return self._execution_context.fetch_next_block()
def _is_partitioned_execution_info(self, e):
return e.status_code == StatusCodes.BAD_REQUEST and e.sub_status == SubStatusCodes.CROSS_PARTITION_QUERY_NOT_SERVABLE
def _get_partitioned_execution_info(self, e):
error_msg = json.loads(e._http_error_message)
return _PartitionedQueryExecutionInfo(json.loads(error_msg['additionalErrorInfo']))
def _create_pipelined_execution_context(self, query_execution_info):
assert self._resource_link, "code bug, resource_link has is required."
execution_context_aggregator = multi_execution_aggregator._MultiExecutionContextAggregator(self._client, self._resource_link, self._query, self._options, query_execution_info)
return _PipelineExecutionContext(self._client, self._options, execution_context_aggregator, query_execution_info)
class _PipelineExecutionContext(_QueryExecutionContextBase):
DEFAULT_PAGE_SIZE = 1000
def __init__(self, client, options, execution_context, query_execution_info):
'''
Constructor
'''
super(_PipelineExecutionContext, self).__init__(client, options)
if options.get('maxItemCount'):
self._page_size = options['maxItemCount']
else:
self._page_size = _PipelineExecutionContext.DEFAULT_PAGE_SIZE
self._execution_context = execution_context
self._endpoint = endpoint_component._QueryExecutionEndpointComponent(execution_context)
order_by = query_execution_info.get_order_by()
if (order_by):
self._endpoint = endpoint_component._QueryExecutionOrderByEndpointComponent(self._endpoint)
top = query_execution_info.get_top()
if not (top is None):
self._endpoint = endpoint_component._QueryExecutionTopEndpointComponent(self._endpoint, top)
aggregates = query_execution_info.get_aggregates()
if aggregates:
self._endpoint = endpoint_component._QueryExecutionAggregateEndpointComponent(self._endpoint, aggregates)
def next(self):
"""Returns the next query result.
:return:
The next query result.
:rtype: dict
:raises StopIteration: If no more result is left.
"""
return next(self._endpoint)
def fetch_next_block(self):
"""Returns a block of results.
This method only exists for backward compatibility reasons. (Because QueryIterable
has exposed fetch_next_block api).
This method internally invokes next() as many times required to collect the
requested fetch size.
:return:
List of results.
:rtype: list
"""
results = []
for _ in xrange(self._page_size):
try:
results.append(next(self))
except StopIteration:
# no more results
break
return results
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