mongo-python-driver/pymongo/server_description.py

# Copyright 2014-present MongoDB, Inc.
#
# 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.

"""Represent one server the driver is connected to."""

from bson import EPOCH_NAIVE
from pymongo.server_type import SERVER_TYPE
from pymongo.ismaster import IsMaster
from pymongo.monotonic import time as _time


class ServerDescription(object):
    """Immutable representation of one server.

    :Parameters:
      - `address`: A (host, port) pair
      - `ismaster`: Optional IsMaster instance
      - `round_trip_time`: Optional float
      - `error`: Optional, the last error attempting to connect to the server
    """

    __slots__ = (
        '_address', '_server_type', '_all_hosts', '_tags', '_replica_set_name',
        '_primary', '_max_bson_size', '_max_message_size',
        '_max_write_batch_size', '_min_wire_version', '_max_wire_version',
        '_round_trip_time', '_me', '_is_writable', '_is_readable',
        '_ls_timeout_minutes', '_error', '_set_version', '_election_id',
        '_cluster_time', '_last_write_date', '_last_update_time')

    def __init__(
            self,
            address,
            ismaster=None,
            round_trip_time=None,
            error=None):
        self._address = address
        if not ismaster:
            ismaster = IsMaster({})

        self._server_type = ismaster.server_type
        self._all_hosts = ismaster.all_hosts
        self._tags = ismaster.tags
        self._replica_set_name = ismaster.replica_set_name
        self._primary = ismaster.primary
        self._max_bson_size = ismaster.max_bson_size
        self._max_message_size = ismaster.max_message_size
        self._max_write_batch_size = ismaster.max_write_batch_size
        self._min_wire_version = ismaster.min_wire_version
        self._max_wire_version = ismaster.max_wire_version
        self._set_version = ismaster.set_version
        self._election_id = ismaster.election_id
        self._cluster_time = ismaster.cluster_time
        self._is_writable = ismaster.is_writable
        self._is_readable = ismaster.is_readable
        self._ls_timeout_minutes = ismaster.logical_session_timeout_minutes
        self._round_trip_time = round_trip_time
        self._me = ismaster.me
        self._last_update_time = _time()
        self._error = error

        if ismaster.last_write_date:
            # Convert from datetime to seconds.
            delta = ismaster.last_write_date - EPOCH_NAIVE
            self._last_write_date = delta.total_seconds()
        else:
            self._last_write_date = None

    @property
    def address(self):
        """The address (host, port) of this server."""
        return self._address

    @property
    def server_type(self):
        """The type of this server."""
        return self._server_type

    @property
    def server_type_name(self):
        """The server type as a human readable string.

        .. versionadded:: 3.4
        """
        return SERVER_TYPE._fields[self._server_type]

    @property
    def all_hosts(self):
        """List of hosts, passives, and arbiters known to this server."""
        return self._all_hosts

    @property
    def tags(self):
        return self._tags

    @property
    def replica_set_name(self):
        """Replica set name or None."""
        return self._replica_set_name

    @property
    def primary(self):
        """This server's opinion about who the primary is, or None."""
        return self._primary

    @property
    def max_bson_size(self):
        return self._max_bson_size

    @property
    def max_message_size(self):
        return self._max_message_size

    @property
    def max_write_batch_size(self):
        return self._max_write_batch_size

    @property
    def min_wire_version(self):
        return self._min_wire_version

    @property
    def max_wire_version(self):
        return self._max_wire_version

    @property
    def set_version(self):
        return self._set_version

    @property
    def election_id(self):
        return self._election_id

    @property
    def cluster_time(self):
        return self._cluster_time

    @property
    def election_tuple(self):
        return self._set_version, self._election_id

    @property
    def me(self):
        return self._me

    @property
    def logical_session_timeout_minutes(self):
        return self._ls_timeout_minutes

    @property
    def last_write_date(self):
        return self._last_write_date

    @property
    def last_update_time(self):
        return self._last_update_time

    @property
    def round_trip_time(self):
        """The current average latency or None."""
        # This override is for unittesting only!
        if self._address in self._host_to_round_trip_time:
            return self._host_to_round_trip_time[self._address]

        return self._round_trip_time

    @property
    def error(self):
        """The last error attempting to connect to the server, or None."""
        return self._error

    @property
    def is_writable(self):
        return self._is_writable

    @property
    def is_readable(self):
        return self._is_readable

    @property
    def mongos(self):
        return self._server_type == SERVER_TYPE.Mongos

    @property
    def is_server_type_known(self):
        return self.server_type != SERVER_TYPE.Unknown

    @property
    def retryable_writes_supported(self):
        """Checks if this server supports retryable writes."""
        return (
            self._ls_timeout_minutes is not None and
            self._server_type in (SERVER_TYPE.Mongos, SERVER_TYPE.RSPrimary))

    # For unittesting only. Use under no circumstances!
    _host_to_round_trip_time = {}