RUBY-560 fixing issue with check_connection_health with auth enabled

Calls from `ShardingPoolManager#check_connection_health` to `client['config']['mongos']` were failing when auth was enabled. Access to this collection requries an authenticated admin user.

In addition, the previous approach of comparing the seed list to the contents of the `mongos` collection was fundamentally flawed since MongoDB keeps every `mongos` that has ever connected to the cluster in that collection (even long gone, inactive `mongos` instances).

We're now simply calling `isMaster()` on each mongos to confirm that 1) it is active and reachable and 2) it is indeed a `mongos`. If either of these conditions are not true, we set `@refresh_required` to true and call close on the member.

Author: Brandon Black

lib/mongo/util/sharding_pool_manager.rb

@@ -27,24 +27,28 @@ def connect
       end
     end
 
-    # We want to refresh to the member with the fastest ping time
-    # but also want to minimize refreshes
-    # We're healthy if the primary is pingable. If this isn't the case,
-    # or the members have changed, set @refresh_required to true, and return.
-    # The config.mongos find can't be part of the connect call chain due to infinite recursion
+    # Checks that each node is healthy (via check_is_master) and that each
+    # node is in fact a mongos. If either criteria are not true, a refresh is
+    # set to be triggered and close() is called on the node.
+    #
+    # @return [Boolean] indicating if a refresh is required.
     def check_connection_health
-      return if thread_local[:locks][:connecting_manager]
-      begin
-        seeds = @client['config']['mongos'].find.map do |mongos|
-                  Support.normalize_seeds(mongos['_id'])
-                end
-        if discovered_seeds != seeds
-          @seeds = seeds
+      @refresh_required = false
+      @members.each do |member|
+        begin
+          config = @client.check_is_master([member.host, member.port])
+          unless config && config.has_key?('msg')
+            @refresh_required = true
+            member.close
+          end
+        rescue OperationTimeout
           @refresh_required = true
+          member.close
         end
-      rescue Mongo::OperationFailure
-        @refresh_required = true
+        break if @refresh_required
       end
+      @refresh_required
     end
+
   end
 end

test/unit/sharding_pool_manager_test.rb

@@ -59,30 +59,5 @@ class ShardingPoolManagerTest < Test::Unit::TestCase
       assert_equal 500, manager.max_bson_size
       assert_equal 700 , manager.max_message_size
     end
-
-    should "maintain seed format when checking connection health" do
-
-      @db.stubs(:command).returns(
-        # First call to get a socket.
-        @ismaster.merge({'ismaster' => true}),
-
-        # Subsequent calls to configure pools.
-        @ismaster.merge({'ismaster' => true}),
-        @ismaster.merge({'secondary' => true, 'maxMessageSizeBytes' => 700}),
-        @ismaster.merge({'secondary' => true, 'maxBsonObjectSize' => 500}),
-        @ismaster.merge({'arbiterOnly' => true})
-      )
-
-      config_db = new_mock_db
-      mongos_coll = mock('collection')
-      mongos_coll.stubs(:find).returns(@hosts.map{|h| {'_id' => h}})
-      config_db.stubs(:[]).with('mongos').returns(mongos_coll)
-      @client.stubs(:[]).with('config').returns(config_db)
-
-      manager = Mongo::ShardingPoolManager.new(@client, @hosts)
-      manager.check_connection_health
-
-      assert manager.seeds.all? {|s| s.is_a?(Array) && s[0].is_a?(String) && s[1].is_a?(Integer)}
-    end
   end
 end