/usr/lib/python3/dist-packages/pymongo/command_cursor.py is in python3-pymongo 3.4.0-1.
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#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""CommandCursor class to iterate over command results."""
import datetime
from collections import deque
from bson.py3compat import integer_types
from pymongo import helpers
from pymongo.errors import AutoReconnect, NotMasterError, OperationFailure
from pymongo.message import _CursorAddress, _GetMore, _convert_exception
class CommandCursor(object):
"""A cursor / iterator over command cursors.
"""
def __init__(self, collection, cursor_info, address, retrieved=0):
"""Create a new command cursor.
"""
self.__collection = collection
self.__id = cursor_info['id']
self.__address = address
self.__data = deque(cursor_info['firstBatch'])
self.__retrieved = retrieved
self.__batch_size = 0
self.__killed = (self.__id == 0)
if "ns" in cursor_info:
self.__ns = cursor_info["ns"]
else:
self.__ns = collection.full_name
def __del__(self):
if self.__id and not self.__killed:
self.__die()
def __die(self):
"""Closes this cursor.
"""
if self.__id and not self.__killed:
self.__collection.database.client.close_cursor(
self.__id, _CursorAddress(self.__address, self.__ns))
self.__killed = True
def close(self):
"""Explicitly close / kill this cursor. Required for PyPy, Jython and
other Python implementations that don't use reference counting
garbage collection.
"""
self.__die()
def batch_size(self, batch_size):
"""Limits the number of documents returned in one batch. Each batch
requires a round trip to the server. It can be adjusted to optimize
performance and limit data transfer.
.. note:: batch_size can not override MongoDB's internal limits on the
amount of data it will return to the client in a single batch (i.e
if you set batch size to 1,000,000,000, MongoDB will currently only
return 4-16MB of results per batch).
Raises :exc:`TypeError` if `batch_size` is not an integer.
Raises :exc:`ValueError` if `batch_size` is less than ``0``.
:Parameters:
- `batch_size`: The size of each batch of results requested.
"""
if not isinstance(batch_size, integer_types):
raise TypeError("batch_size must be an integer")
if batch_size < 0:
raise ValueError("batch_size must be >= 0")
self.__batch_size = batch_size == 1 and 2 or batch_size
return self
def __send_message(self, operation):
"""Send a getmore message and handle the response.
"""
client = self.__collection.database.client
listeners = client._event_listeners
publish = listeners.enabled_for_commands
try:
response = client._send_message_with_response(
operation, address=self.__address)
except AutoReconnect:
# Don't try to send kill cursors on another socket
# or to another server. It can cause a _pinValue
# assertion on some server releases if we get here
# due to a socket timeout.
self.__killed = True
raise
cmd_duration = response.duration
rqst_id = response.request_id
from_command = response.from_command
if publish:
start = datetime.datetime.now()
try:
doc = helpers._unpack_response(response.data,
self.__id,
self.__collection.codec_options)
if from_command:
helpers._check_command_response(doc['data'][0])
except OperationFailure as exc:
self.__killed = True
if publish:
duration = (datetime.datetime.now() - start) + cmd_duration
listeners.publish_command_failure(
duration, exc.details, "getMore", rqst_id, self.__address)
raise
except NotMasterError as exc:
# Don't send kill cursors to another server after a "not master"
# error. It's completely pointless.
self.__killed = True
if publish:
duration = (datetime.datetime.now() - start) + cmd_duration
listeners.publish_command_failure(
duration, exc.details, "getMore", rqst_id, self.__address)
client._reset_server_and_request_check(self.address)
raise
except Exception as exc:
if publish:
duration = (datetime.datetime.now() - start) + cmd_duration
listeners.publish_command_failure(
duration, _convert_exception(exc), "getMore", rqst_id,
self.__address)
raise
if from_command:
cursor = doc['data'][0]['cursor']
documents = cursor['nextBatch']
self.__id = cursor['id']
self.__retrieved += len(documents)
else:
documents = doc["data"]
self.__id = doc["cursor_id"]
self.__retrieved += doc["number_returned"]
if publish:
duration = (datetime.datetime.now() - start) + cmd_duration
# Must publish in getMore command response format.
res = {"cursor": {"id": self.__id,
"ns": self.__collection.full_name,
"nextBatch": documents},
"ok": 1}
listeners.publish_command_success(
duration, res, "getMore", rqst_id, self.__address)
if self.__id == 0:
self.__killed = True
self.__data = deque(documents)
def _refresh(self):
"""Refreshes the cursor with more data from the server.
Returns the length of self.__data after refresh. Will exit early if
self.__data is already non-empty. Raises OperationFailure when the
cursor cannot be refreshed due to an error on the query.
"""
if len(self.__data) or self.__killed:
return len(self.__data)
if self.__id: # Get More
dbname, collname = self.__ns.split('.', 1)
self.__send_message(
_GetMore(dbname,
collname,
self.__batch_size,
self.__id,
self.__collection.codec_options))
else: # Cursor id is zero nothing else to return
self.__killed = True
return len(self.__data)
@property
def alive(self):
"""Does this cursor have the potential to return more data?
Even if :attr:`alive` is ``True``, :meth:`next` can raise
:exc:`StopIteration`. Best to use a for loop::
for doc in collection.aggregate(pipeline):
print(doc)
.. note:: :attr:`alive` can be True while iterating a cursor from
a failed server. In this case :attr:`alive` will return False after
:meth:`next` fails to retrieve the next batch of results from the
server.
"""
return bool(len(self.__data) or (not self.__killed))
@property
def cursor_id(self):
"""Returns the id of the cursor."""
return self.__id
@property
def address(self):
"""The (host, port) of the server used, or None.
.. versionadded:: 3.0
"""
return self.__address
def __iter__(self):
return self
def next(self):
"""Advance the cursor."""
if len(self.__data) or self._refresh():
coll = self.__collection
return coll.database._fix_outgoing(self.__data.popleft(), coll)
else:
raise StopIteration
__next__ = next
def __enter__(self):
return self
def __exit__(self, exc_type, exc_val, exc_tb):
self.__die()
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