# Copyright (C) 2015-2017 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 class Cluster module Topology # Defines behaviour for when a cluster is in an unknown state. # # @since 2.0.0 class Unknown include Loggable include Monitoring::Publishable # The display name for the topology. # # @since 2.0.0 NAME = 'Unknown'.freeze # @return [ Hash ] options The options. attr_reader :options # @return [ Monitoring ] monitoring The monitoring. attr_reader :monitoring # Get the display name. # # @example Get the display name. # Unknown.display_name # # @return [ String ] The display name. # # @since 2.0.0 def display_name NAME end # Elect a primary server within this topology. # # @example Elect a primary server. # topology.elect_primary(description, servers) # # @param [ Server::Description ] description The description of the # elected primary. # @param [ Array ] servers The list of known servers to the # cluster. # # @return [ Sharded, ReplicaSet ] The new topology. def elect_primary(description, servers) if description.mongos? sharded = Sharded.new(options, monitoring) topology_changed(sharded) sharded else initialize_replica_set(description, servers) end end # Determine if the topology would select a readable server for the # provided candidates and read preference. # # @example Is a readable server present? # topology.has_readable_server?(cluster, server_selector) # # @param [ Cluster ] cluster The cluster. # @param [ ServerSelector ] server_selector The server # selector. # # @return [ false ] An Unknown topology will never have a readable server. # # @since 2.4.0 def has_readable_server?(cluster, server_selector = nil); false; end # Determine if the topology would select a writable server for the # provided candidates. # # @example Is a writable server present? # topology.has_writable_server?(servers) # # @param [ Cluster ] cluster The cluster. # # @return [ false ] An Unknown topology will never have a writable server. # # @since 2.4.0 def has_writable_server?(cluster); false; end # Initialize the topology with the options. # # @example Initialize the topology. # Unknown.new(options) # # @param [ Hash ] options The options. # @param [ Monitoring ] monitoring The monitoring. # @param [ Array ] seeds The seeds. # # @since 2.0.0 def initialize(options, monitoring, seeds = []) @options = options @monitoring = monitoring @seeds = seeds end # An unknown topology is not a replica set. # # @example Is the topology a replica set? # Unknown.replica_set? # # @return [ false ] Always false. # # @since 2.0.0 def replica_set?; false; end # Unknown topologies have no replica set name. # # @example Get the replica set name. # unknown.replica_set_name # # @return [ nil ] Always nil. # # @since 2.0.0 def replica_set_name; nil; end # Select appropriate servers for this topology. # # @example Select the servers. # Unknown.servers(servers) # # @param [ Array ] servers The known servers. # # @raise [ Unknown ] Cannot select servers when the topology is # unknown. # # @since 2.0.0 def servers(servers) [] end # An unknown topology is not sharded. # # @example Is the topology sharded? # Unknown.sharded? # # @return [ false ] Always false. # # @since 2.0.0 def sharded?; false; end # An unknown topology is not single. # # @example Is the topology single? # Unknown.single? # # @return [ true ] Always false. # # @since 2.0.0 def single?; false; end # An unknown topology is unknown. # # @example Is the topology unknown? # Unknown.unknown? # # @return [ true ] Always true. # # @since 2.0.0 def unknown?; true; end # Whether a server description's hosts may be added to the cluster. # # @example Check if a description's hosts may be added to the cluster. # topology.add_hosts?(description, servers) # # @param [ Mongo::Server::Description ] description The description. # @param [ Array ] servers The cluster servers. # # @return [ true, false ] Whether a description's hosts may be added. # # @since 2.0.6 def add_hosts?(description, servers) !(description.unknown? || description.ghost?) end # Whether a description can be used to remove hosts from the cluster. # # @example Check if a description can be used to remove hosts from the cluster. # topology.remove_hosts?(description) # # @param [ Mongo::Server::Description ] description The description. # # @return [ true, false ] Whether hosts may be removed from the cluster. # # @since 2.0.6 def remove_hosts?(description) description.standalone? end # Whether a specific server in the cluster can be removed, given a description. # # @example Check if a specific server can be removed from the cluster. # topology.remove_server?(description, server) # # @param [ Mongo::Server::Description ] description The description. # @param [ Mongo::Serve ] server The server in question. # # @return [ true, false ] Whether the server can be removed from the cluster. # # @since 2.0.6 def remove_server?(description, server) description.standalone? && description.is_server?(server) end # Notify the topology that a standalone was discovered. # # @example Notify the topology that a standalone was discovered. # topology.standalone_discovered # # @return [ Topology::Unknown, Topology::Single ] Either self or a # new Single topology. # # @since 2.0.6 def standalone_discovered if @seeds.size == 1 single = Single.new(options, monitoring, @seeds) topology_changed(single) single else self end end # Notify the topology that a member was discovered. # # @example Notify the topology that a member was discovered. # topology.member_discovered # # @since 2.4.0 def member_discovered publish_sdam_event( Monitoring::TOPOLOGY_CHANGED, Monitoring::Event::TopologyChanged.new(self, self) ) end private def initialize_replica_set(description, servers) servers.each do |server| if server.standalone? && server.address != description.address server.description.unknown! end end replica_set = ReplicaSet.new(options.merge(:replica_set => description.replica_set_name), monitoring) topology_changed(replica_set) replica_set end def topology_changed(new_topology) publish_sdam_event( Monitoring::TOPOLOGY_CHANGED, Monitoring::Event::TopologyChanged.new(self, new_topology) ) end end end end end