RUBY-932 Update Server Discovery and Monitoring code and tests

Author: estolfo

lib/mongo/cluster.rb

@@ -95,8 +95,7 @@ def initialize(seeds, options = {})
       @topology = Topology.initial(seeds, options)
       @slave_ok = @topology.single? unless options[:read]
 
-      subscribe_to(Event::SERVER_ADDED, Event::ServerAdded.new(self))
-      subscribe_to(Event::SERVER_REMOVED, Event::ServerRemoved.new(self))
+      subscribe_to(Event::DESCRIPTION_CHANGED, Event::DescriptionChanged.new(self))
       subscribe_to(Event::PRIMARY_ELECTED, Event::PrimaryElected.new(self))
 
       seeds.each{ |seed| add(seed) }
@@ -141,7 +140,7 @@ def elect_primary!(description)
       @topology = topology.elect_primary(description, @servers)
     end
 
-    # Removed the server from the cluster for the provided address, if it
+    # Remove the server from the cluster for the provided address, if it
     # exists.
     #
     # @example Remove the server from the cluster.
@@ -186,6 +185,36 @@ def servers
       topology.servers(@servers.compact).compact
     end
 
+    # Add hosts in a description to the cluster.
+    #
+    # @example Add hosts in a description to the cluster.
+    #   cluster.add_hosts(description)
+    #
+    # @param [ Mongo::Server::Description ] description The description.
+    #
+    # @since 2.0.6
+    def add_hosts(description)
+      if topology.add_hosts?(description, @servers)
+        description.servers.each { |s| add(s) }
+      end
+    end
+
+    # Remove hosts in a description from the cluster.
+    #
+    # @example Remove hosts in a description from the cluster.
+    #   cluster.remove_hosts(description)
+    #
+    # @param [ Mongo::Server::Description ] description The description.
+    #
+    # @since 2.0.6
+    def remove_hosts(description)
+      if topology.remove_hosts?(description)
+        @servers.each do |s|
+          remove(s.address.to_s) if topology.remove_server?(description, s)
+        end
+      end
+    end
+
     # Create a cluster for the provided client, for use when we don't want the
     # client's original cluster instance to be the same.
     #

lib/mongo/cluster/topology/replica_set.rb

@@ -125,6 +125,56 @@ def servers(servers)
           end
         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<Mongo::Server> ] servers The cluster servers.
+        #
+        # @return [ true, false ] Whether a description's hosts may be added.
+        #
+        # @since 2.0.6
+        def add_hosts?(description, servers)
+          if !has_primary?(servers)
+            member_of_this_set?(description)
+          end
+        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.config.empty? &&
+            (description.primary? ||
+              description.hosts.empty? ||
+                !member_of_this_set?(description))
+        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)
+          remove_self?(description, server) ||
+            (member_of_this_set?(description) && !description.included?(server))
+        end
+
         # A replica set topology is not sharded.
         #
         # @example Is the topology sharded?
@@ -154,6 +204,23 @@ def single?; false; end
         #
         # @since 2.0.0
         def unknown?; false; end
+
+        private
+
+        def has_primary?(servers)
+          servers.find { |s| s.primary? }
+        end
+
+        def member_of_this_set?(description)
+          description.replica_set_member? &&
+            description.replica_set_name == replica_set_name
+        end
+
+        def remove_self?(description, server)
+          !member_of_this_set?(description) &&
+            description.self?(server) &&
+              !description.ghost?
+        end
       end
     end
   end

lib/mongo/cluster/topology/sharded.rb

@@ -97,6 +97,50 @@ def servers(servers)
           servers.select{ |server| server.mongos? }
         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<Mongo::Server> ] servers The cluster servers.
+        #
+        # @return [ false ] A description's hosts are never added to a
+        #   sharded cluster.
+        #
+        # @since 2.0.6
+        def add_hosts?(description, servers); false; 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 ] A description can always be used to remove hosts
+        #   from a sharded cluster.
+        #
+        # @since 2.0.6
+        def remove_hosts?(description); true; 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)
+          remove_self?(description, server) ||
+            !(server.mongos? || server.unknown?)
+        end
+
         # A sharded topology is sharded.
         #
         # @example Is the topology sharded?
@@ -126,6 +170,12 @@ def single?; false; end
         #
         # @since 2.0.0
         def unknown?; false; end
+
+        private
+
+        def remove_self?(description, server)
+          description.self?(server) && !description.mongos?
+        end
       end
     end
   end

lib/mongo/cluster/topology/single.rb

@@ -101,6 +101,47 @@ def servers(servers, name = nil)
           [ servers.detect { |server| !server.unknown? } ]
         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<Mongo::Server> ] servers The cluster servers.
+        #
+        # @return [ false ] A description's hosts are never added to a
+        #   cluster of Single topology.
+        #
+        # @since 2.0.6
+        def add_hosts?(description, servers); false; 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 ] A description can never be used to remove hosts
+        #   from a cluster of Single topology.
+        #
+        # @since 2.0.6
+        def remove_hosts?(description); false; 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 [ false ] A server is never removed from a cluster of Single topology.
+        #
+        # @since 2.0.6
+        def remove_server?(description, server); false; end
+
         # A single topology is not sharded.
         #
         # @example Is the topology sharded?

lib/mongo/cluster/topology/unknown.rb

@@ -139,6 +139,50 @@ def single?; false; end
         # @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<Mongo::Server> ] 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.self?(server)
+        end
+
         private
 
         def initialize_replica_set(description, servers)

lib/mongo/event.rb

@@ -16,8 +16,7 @@
 require 'mongo/event/publisher'
 require 'mongo/event/subscriber'
 require 'mongo/event/primary_elected'
-require 'mongo/event/server_added'
-require 'mongo/event/server_removed'
+require 'mongo/event/description_changed'
 
 module Mongo
   module Event
@@ -27,14 +26,9 @@ module Event
     # @since 2.0.0
     PRIMARY_ELECTED = 'primary_elected'.freeze
 
-    # When a server is to be added to a cluster.
-    #
-    # @since 2.0.0
-    SERVER_ADDED = 'server_added'.freeze
-
     # When a server is to be removed from a cluster.
     #
-    # @since 2.0.0
-    SERVER_REMOVED = 'server_removed'.freeze
+    # @since 2.0.5
+    DESCRIPTION_CHANGED = 'description_changed'.freeze
   end
 end

lib/mongo/event/server_added.rb renamed to lib/mongo/event/description_changed.rb

@@ -16,10 +16,10 @@
 module Mongo
   module Event
 
-    # This handles host added events for server descriptions.
+    # This handles a change in description.
     #
-    # @since 2.0.0
-    class ServerAdded
+    # @since 2.0.5
+    class DescriptionChanged
 
       # @return [ Mongo::Cluster ] cluster The event publisher.
       attr_reader :cluster
@@ -45,8 +45,9 @@ def initialize(cluster)
       # @param [ Address ] address The added host.
       #
       # @since 2.0.0
-      def handle(address)
-        cluster.add(address)
+      def handle(updated)
+        cluster.add_hosts(updated)
+        cluster.remove_hosts(updated)
       end
     end
   end