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# frozen_string_literal: true
# rubocop:todo all
# Copyright (C) 2014-2020 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.
module Mongo
module ServerSelector
# Encapsulates specifications for selecting near servers given a list
# of candidates.
#
# @since 2.0.0
class Nearest < Base
# Name of the this read preference in the server's format.
#
# @since 2.5.0
SERVER_FORMATTED_NAME = 'nearest'.freeze
# Get the name of the server mode type.
#
# @example Get the name of the server mode for this preference.
# preference.name
#
# @return [ Symbol ] :nearest
#
# @since 2.0.0
def name
:nearest
end
# Whether the secondaryOk bit should be set on wire protocol messages.
# I.e. whether the operation can be performed on a secondary server.
#
# @return [ true ] true
# @api private
def secondary_ok?
true
end
# Whether tag sets are allowed to be defined for this server preference.
#
# @return [ true ] true
#
# @since 2.0.0
def tags_allowed?
true
end
# Whether the hedge option is allowed to be defined for this server preference.
#
# @return [ true ] true
def hedge_allowed?
true
end
# Convert this server preference definition into a format appropriate
# for sending to a MongoDB server (i.e., as a command field).
#
# @return [ Hash ] The server preference formatted as a command field value.
#
# @since 2.0.0
def to_doc
full_doc
end
# Convert this server preference definition into a value appropriate
# for sending to a mongos.
#
# This method may return nil if the read preference should not be sent
# to a mongos.
#
# @return [ Hash | nil ] The server preference converted to a mongos
# command field value.
#
# @since 2.0.0
alias :to_mongos :to_doc
private
# Select the near servers taking into account any defined tag sets and
# local threshold between the nearest server and other servers.
#
# @return [ Array ] The nearest servers from the list of candidates.
#
# @since 2.0.0
def select_in_replica_set(candidates)
matching_servers = filter_stale_servers(candidates, primary(candidates).first)
matching_servers = match_tag_sets(matching_servers) unless tag_sets.empty?
near_servers(matching_servers)
end
def max_staleness_allowed?
true
end
end
end
end
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