From c25b1f1585d4ab1d13e5f710c33d218d47d4353a Mon Sep 17 00:00:00 2001
From: Kyle Banker <kylebanker@gmail.com>
Date: Mon, 5 Dec 2011 12:27:19 -0500
Subject: [PATCH] RUBY-376 separate original seeds nodes from discovered ones

---
 lib/mongo/repl_set_connection.rb | 27 +++++++++-----------
 lib/mongo/util/pool_manager.rb   | 42 ++++++++++++++++++++++----------
 2 files changed, 41 insertions(+), 28 deletions(-)

diff --git a/lib/mongo/repl_set_connection.rb b/lib/mongo/repl_set_connection.rb
index d2a160c..20bd1e2 100644
--- a/lib/mongo/repl_set_connection.rb
+++ b/lib/mongo/repl_set_connection.rb
@@ -91,8 +91,10 @@ module Mongo
         raise MongoArgumentError, "A ReplSetConnection requires at least one seed node."
       end
 
-      # The list of seed nodes
+      # The original, immutable list of seed node.
+      # TODO: add a method for replacing this list of node.
       @seeds = args
+      @seeds.freeze
 
       # TODO: get rid of this
       @nodes = @seeds.dup
@@ -152,11 +154,12 @@ module Mongo
     def connect
       log(:info, "Connecting...")
       return if @connected
-      manager = PoolManager.new(self, @seeds)
-      @manager = manager
-      manager.connect
 
-      update_config(manager)
+      discovered_seeds = @manager ? @manager.seeds : []
+      @manager = PoolManager.new(self, discovered_seeds)
+
+      @manager.connect
+      @refresh_version += 1
 
       if @require_primary && self.primary.nil? #TODO: in v2.0, we'll let this be optional and do a lazy connect.
         close
@@ -201,13 +204,15 @@ module Mongo
     #   to get the refresh lock.
     def hard_refresh!
       log(:info, "Initiating hard refresh...")
-      background_manager = PoolManager.new(self, @seeds)
+      discovered_seeds = @manager ? @manager.seeds : []
+      background_manager = PoolManager.new(self, discovered_seeds | @original_seeds)
       background_manager.connect
 
       # TODO: make sure that connect has succeeded
       old_manager = @manager
-      update_config(background_manager)
+      @manager = background_manager
       old_manager.close(:soft => true)
+      @refresh_version += 1
 
       return true
     end
@@ -479,14 +484,6 @@ module Mongo
       connect if should_connect
     end
 
-    # Given a pool manager, update this connection's
-    # view of the replica set.
-    def update_config(new_manager)
-      @manager = new_manager
-      @seeds   = @manager.seeds.dup
-      @refresh_version += 1
-    end
-
     # Checkout a socket connected to a node with one of
     # the provided tags. If no such node exists, raise
     # an exception.
diff --git a/lib/mongo/util/pool_manager.rb b/lib/mongo/util/pool_manager.rb
index 65faf84..6654cfd 100644
--- a/lib/mongo/util/pool_manager.rb
+++ b/lib/mongo/util/pool_manager.rb
@@ -1,15 +1,22 @@
 module Mongo
   class PoolManager
 
-    attr_reader :connection, :seeds, :arbiters, :primary, :secondaries,
-      :primary_pool, :read_pool, :secondary_pools, :hosts, :nodes, :max_bson_size,
+    attr_reader :connection, :arbiters, :primary, :secondaries, :primary_pool,
+      :read_pool, :secondary_pools, :hosts, :nodes, :max_bson_size,
       :tags_to_pools, :tag_map, :members
 
-    def initialize(connection, seeds)
+    # Create a new set of connection pools.
+    #
+    # The pool manager will by default use the original seed list passed
+    # to the connection objects, accessible via connection.seeds. In addition,
+    # the user may pass an additional list of seeds nodes discovered in real
+    # time. The union of these lists will be used when attempting to connect,
+    # with the newly-discovered nodes being used first.
+    def initialize(connection, seeds=[])
       @connection = connection
+      @original_seeds = connection.seeds
       @seeds = seeds
       @previously_connected = false
-      @refresh_required = false
     end
 
     def inspect
@@ -17,14 +24,12 @@ module Mongo
     end
 
     def connect
-      if @previously_connected
-        close
-      end
+      close if @previously_connected
 
       initialize_data
       members = connect_to_members
       initialize_pools(members)
-      update_seed_list(members)
+      cache_discovered_seeds(members)
       set_read_pool
       set_tag_mappings
 
@@ -35,7 +40,7 @@ module Mongo
     # We're healthy if all members are pingable and if the view
     # of the replica set returned by isMaster is equivalent
     # to our view. If any of these isn't the case,
-    # set @refresh_require to true, and return.
+    # set @refresh_required to true, and return.
     def check_connection_health
       begin
         seed = get_valid_seed_node
@@ -101,6 +106,12 @@ module Mongo
       end
     end
 
+    # The set of nodes that this class has discovered and
+    # successfully connected to.
+    def seeds
+      @seeds
+    end
+
     private
 
     def validate_existing_member(member)
@@ -124,6 +135,7 @@ module Mongo
     end
 
     def initialize_data
+      @seeds = []
       @primary = nil
       @primary_pool = nil
       @read_pool = nil
@@ -134,6 +146,7 @@ module Mongo
       @members = Set.new
       @tags_to_pools = {}
       @tag_map = {}
+      @refresh_required = false
     end
 
     # Connect to each member of the replica set
@@ -255,7 +268,7 @@ module Mongo
     #
     # If we don't get a response, raise an exception.
     def get_valid_seed_node
-      @seeds.each do |seed|
+      seed_list.each do |seed|
         node = Mongo::Node.new(self.connection, seed)
         if !node.connect
           next
@@ -270,9 +283,12 @@ module Mongo
         "#{@seeds.map {|s| "#{s[0]}:#{s[1]}" }.join(', ')}"
     end
 
-    def update_seed_list(members)
-      current_members = members.map { |n| n.host_port }
-      @seeds = (current_members + @seeds).uniq
+    def seed_list
+      @seeds | @original_seeds
+    end
+
+    def cache_discovered_seeds(members)
+      @seeds = members.map { |n| n.host_port }
     end
 
   end