RUBY-949 Initialize topologies to Unknown and discover standalones

lib/mongo/cluster.rb

@@ -91,6 +91,7 @@ def initialize(seeds, options = {})
       @topology = Topology.initial(seeds, options)
       @update_lock = Mutex.new
 
+      subscribe_to(Event::STANDALONE_DISCOVERED, Event::StandaloneDiscovered.new(self))
       subscribe_to(Event::DESCRIPTION_CHANGED, Event::DescriptionChanged.new(self))
       subscribe_to(Event::PRIMARY_ELECTED, Event::PrimaryElected.new(self))
 
@@ -136,6 +137,19 @@ def elect_primary!(description)
       @topology = topology.elect_primary(description, servers_list)
     end
 
+    # Notify the cluster that a standalone server was discovered so that the
+    # topology can be updated accordingly.
+    #
+    # @example Notify the cluster that a standalone server was discovered.
+    #   cluster.standalone_discovered
+    #
+    # @return [ Topology ] The cluster topology.
+    #
+    # @since 2.0.6
+    def standalone_discovered
+      @topology = topology.standalone_discovered
+    end
+
     # Remove the server from the cluster for the provided address, if it
     # exists.
     #

lib/mongo/cluster/topology.rb

@@ -48,12 +48,11 @@ module Topology
       # @since 2.0.0
       def initial(seeds, options)
         if options.has_key?(:connect)
-          return OPTIONS.fetch(options[:connect]).new(options, seeds)
-        end
-        if options.has_key?(:replica_set)
+          OPTIONS.fetch(options[:connect]).new(options, seeds)
+        elsif options.has_key?(:replica_set)
           ReplicaSet.new(options, seeds)
         else
-          seeds.size > 1 ? Unknown.new(options, seeds) : Single.new(options, seeds)
+          Unknown.new(options, seeds)
         end
       end
     end

lib/mongo/cluster/topology/replica_set.rb

@@ -203,6 +203,16 @@ def single?; false; end
         # @since 2.0.0
         def unknown?; false; end
 
+        # Notify the topology that a standalone was discovered.
+        #
+        # @example Notify the topology that a standalone was discovered.
+        #   topology.standalone_discovered
+        #
+        # @return [ Topology::ReplicaSet ] Always returns self.
+        #
+        # @since 2.0.6
+        def standalone_discovered; self; end
+
         private
 
         def has_primary?(servers)

lib/mongo/cluster/topology/sharded.rb

@@ -171,6 +171,16 @@ def single?; false; end
         # @since 2.0.0
         def unknown?; false; end
 
+        # Notify the topology that a standalone was discovered.
+        #
+        # @example Notify the topology that a standalone was discovered.
+        #   topology.standalone_discovered
+        #
+        # @return [ Topology::Sharded ] Always returns self.
+        #
+        # @since 2.0.6
+        def standalone_discovered; self; end
+
         private
 
         def remove_self?(description, server)

lib/mongo/cluster/topology/single.rb

@@ -171,6 +171,16 @@ def single?; true; end
         #
         # @since 2.0.0
         def unknown?; false; end
+
+        # Notify the topology that a standalone was discovered.
+        #
+        # @example Notify the topology that a standalone was discovered.
+        #   topology.standalone_discovered
+        #
+        # @return [ Topology::Single ] Always returns self.
+        #
+        # @since 2.0.6
+        def standalone_discovered; self; end
       end
     end
   end

lib/mongo/cluster/topology/unknown.rb

@@ -72,6 +72,7 @@ def elect_primary(description, servers)
         # @since 2.0.0
         def initialize(options, seeds = [])
           @options = options
+          @seeds = seeds
         end
 
         # An unknown topology is not a replica set.
@@ -183,6 +184,23 @@ 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.new(options, @seeds)
+          else
+            self
+          end
+        end
+
         private
 
         def initialize_replica_set(description, servers)

lib/mongo/event.rb

@@ -17,10 +17,16 @@
 require 'mongo/event/subscriber'
 require 'mongo/event/primary_elected'
 require 'mongo/event/description_changed'
+require 'mongo/event/standalone_discovered'
 
 module Mongo
   module Event
 
+    # When a standalone is discovered.
+    #
+    # @since 2.0.6
+    STANDALONE_DISCOVERED = 'standalone_discovered'.freeze
+
     # When a server is elected primary.
     #
     # @since 2.0.0

lib/mongo/event/standalone_discovered.rb

@@ -0,0 +1,53 @@
+# Copyright (C) 2015 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 Event
+
+    # This handles when a standalone is discovered.
+    #
+    # @since 2.0.6
+    class StandaloneDiscovered
+
+      # @return [ Mongo::Cluster ] cluster The event publisher.
+      attr_reader :cluster
+
+      # Initialize the new standalone discovered event handler.
+      #
+      # @example Create the new handler.
+      #   StandaloneDiscovered.new(cluster)
+      #
+      # @param [ Mongo::Cluster ] cluster The cluster to publish from.
+      #
+      # @since 2.0.6
+      def initialize(cluster)
+        @cluster = cluster
+      end
+
+      # This event tells the cluster to notify its topology that a standalone
+      # was discovered.
+      #
+      # @example Handle the event.
+      #   standalone_discovered.handle(description)
+      #
+      # @param [ Server::Description ] description The description of the
+      #   server.
+      #
+      # @since 2.0.6
+      def handle(description)
+        cluster.standalone_discovered
+      end
+    end
+  end
+end

lib/mongo/server/description/inspector.rb

@@ -14,6 +14,7 @@
 
 require 'mongo/server/description/inspector/primary_elected'
 require 'mongo/server/description/inspector/description_changed'
+require 'mongo/server/description/inspector/standalone_discovered'
 
 module Mongo
   class Server
@@ -31,6 +32,7 @@ class Inspector
         #
         # @since 2.0.0
         INSPECTORS = [
+            Inspector::StandaloneDiscovered,
             Inspector::DescriptionChanged,
             Inspector::PrimaryElected
         ].freeze

lib/mongo/server/description/inspector/standalone_discovered.rb

@@ -0,0 +1,56 @@
+# Copyright (C) 2015 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 Server
+    class Description
+      class Inspector
+
+        # Handles notifying the cluster that a standalone was discovered.
+        #
+        # @since 2.0.6
+        class StandaloneDiscovered
+          include Event::Publisher
+
+          # Instantiate the standalone discovered inspection.
+          #
+          # @example Instantiate the inspection.
+          #   StandaloneDiscovered.new(listeners)
+          #
+          # @param [ Event::Listeners ] event_listeners The event listeners.
+          #
+          # @since 2.0.6
+          def initialize(event_listeners)
+            @event_listeners = event_listeners
+          end
+
+          # Run the standalone discovered inspection.
+          #
+          # @example Run the inspection.
+          #   StandaloneDiscovered.run(description, {})
+          #
+          # @param [ Description ] description The server description.
+          # @param [ Description ] updated The updated description.
+          #
+          # @since 2.0.6
+          def run(description, updated)
+            if !description.standalone? && updated.standalone?
+              publish(Event::STANDALONE_DISCOVERED, updated)
+            end
+          end
+        end
+      end
+    end
+  end
+end

spec/mongo/cluster/topology_spec.rb

@@ -60,26 +60,26 @@
           described_class.initial([], {})
         end
 
-        it 'returns a single topology' do
-          expect(topology).to be_a(Mongo::Cluster::Topology::Single)
+        it 'returns an unknown topology' do
+          expect(topology).to be_a(Mongo::Cluster::Topology::Unknown)
         end
       end
 
       context 'when provided a single mongos', if: single_mongos? do
 
         let(:topology) do
-          described_class.initial(ADDRESSES, {})
+          described_class.initial(ADDRESSES, TEST_OPTIONS)
         end
 
-        it 'returns a single topology' do
-          expect(topology).to be_a(Mongo::Cluster::Topology::Single)
+        it 'returns a sharded topology' do
+          expect(topology).to be_a(Mongo::Cluster::Topology::Sharded)
         end
       end
 
       context 'when provided a single replica set member', if: single_rs_member? do
 
         let(:topology) do
-          described_class.initial(ADDRESSES, {})
+          described_class.initial(ADDRESSES, TEST_OPTIONS)
         end
 
         it 'returns a single topology' do

spec/mongo/server_discovery_and_monitoring_spec.rb

@@ -32,7 +32,7 @@ def family(host)
         # @since 2.0.0
         class Mongo::Server
 
-          # The contructor keeps the same API, but does not instantiate a
+          # The constructor keeps the same API, but does not instantiate a
           # monitor and run it.
           def initialize(address, cluster, event_listeners, options = {})
             @address = address

spec/support/sdam/sharded/single_mongos.yml

@@ -0,0 +1,33 @@
+description: "Single mongos"
+
+uri: "mongodb://a"
+
+phases: [
+
+    {
+        responses: [
+
+                ["a:27017", {
+
+                    ok: 1,
+                    ismaster: true,
+                    msg: "isdbgrid"
+                }]
+        ],
+
+        outcome: {
+
+            servers: {
+
+                "a:27017": {
+
+                    type: "Mongos",
+                    setName:
+                }
+            },
+
+            topologyType: "Sharded",
+            setName:
+        }
+    }
+]