Replica Set connection improvements for refresh and multi-threaded apps.

lib/mongo/collection.rb

@@ -53,7 +53,7 @@ module Mongo
     def initialize(name, db, opts={})
       if db.is_a?(String) && name.is_a?(Mongo::DB)
         warn "Warning: the order of parameters to initialize a collection have changed. " +
-             "Please specify the collection name first, followed by the db. This will be made permanent"
+             "Please specify the collection name first, followed by the db. This will be made permanent" +
              "in v2.0."
         db, name = name, db
       end

lib/mongo/connection.rb

@@ -30,9 +30,6 @@ module Mongo
     Mutex = ::Mutex
     ConditionVariable = ::ConditionVariable
 
-    # Abort connections if a ConnectionError is raised.
-    Thread.abort_on_exception = true
-
     DEFAULT_PORT = 27017
     STANDARD_HEADER_SIZE = 16
     RESPONSE_HEADER_SIZE = 20

lib/mongo/repl_set_connection.rb

@@ -23,7 +23,7 @@ module Mongo
   # Instantiates and manages connections to a MongoDB replica set.
   class ReplSetConnection < Connection
     attr_reader :nodes, :secondaries, :arbiters, :secondary_pools,
-      :replica_set_name, :read_pool, :seeds, :tags_to_pools, :refresh_interval
+      :replica_set_name, :read_pool, :seeds, :tags_to_pools, :refresh_interval, :auto_refresh
 
     # Create a connection to a MongoDB replica set.
     #
@@ -62,6 +62,8 @@ module Mongo
     #   prevent you from having to reconnect manually.
     # @option opts [Integer] :refresh_interval (90) If :auto_refresh is enabled, this is the number of seconds
     #   that the background thread will sleep between calls to check the replica set's state.
+    # @option opts [Boolean] :require_primary (true) If true, require a primary node for the connection
+    #   to succeed. Otherwise, connection will succeed as long as there's at least one secondary.
     #
     # @example Connect to a replica set and provide two seed nodes. Note that the number of seed nodes does
     #   not have to be equal to the number of replica set members. The purpose of seed nodes is to permit
@@ -148,6 +150,9 @@ module Mongo
         @replica_set_name = opts[:name]
       end
 
+      # Require a primary node to connect?
+      @require_primary = opts.fetch(:require_primary, false)
+
       setup(opts)
     end
 
@@ -158,6 +163,7 @@ module Mongo
 
     # Initiate a connection to the replica set.
     def connect
+      log(:debug, "Connecting.")
       sync_synchronize(:EX) do
         return if @connected
         manager = PoolManager.new(self, @seeds)
@@ -166,8 +172,10 @@ module Mongo
         update_config(manager)
         initiate_auto_refresh
 
-        if @primary.nil? #TODO: in v2.0, we'll let this be optional and do a lazy connect.
+        if @require_primary && @primary.nil? #TODO: in v2.0, we'll let this be optional and do a lazy connect.
           raise ConnectionFailure, "Failed to connect to primary node."
+        elsif !@read_pool
+          raise ConnectionFailure, "Failed to connect to any node."
         else
           @connected = true
         end
@@ -205,13 +213,16 @@ module Mongo
       end
 
       background_manager = Thread.current[:background]
-      if background_manager.update_required?(@hosts)
+
+      # Return if another thread is already in the process of refreshing.
+      return if sync_exclusive?
+
       sync_synchronize(:EX) do
+        log(:debug, "Refreshing...")
         background_manager.connect
         update_config(background_manager)
       end
     end
-    end
 
     def connected?
       @primary_pool || @read_pool
@@ -259,8 +270,8 @@ module Mongo
     # Close the connection to the database.
     # TODO: we should get an exclusive lock here.
     def close
+      sync_synchronize(:EX) do
         @connected = false
-
         super
 
         if @refresh_thread
@@ -289,6 +300,7 @@ module Mongo
         @tags_to_pools.clear
         @sockets_to_pools.clear
       end
+    end
 
     # If a ConnectionFailure is raised, this method will be called
     # to close the connection and reset connection values.
@@ -342,17 +354,25 @@ module Mongo
     # if no read pool has been defined.
     def checkout_reader
       connect unless connected?
+      socket = get_socket_from_pool(@read_pool)
 
-      sync_synchronize(:SH) do
+      if !socket
-        socket = @read_pool.checkout
+        refresh
-        @sockets_to_pools[socket] = @read_pool
+        socket = get_socket_from_pool(@primary_pool)
+      end
+
+      if socket
         socket
+      else
+        raise ConnectionFailure.new("Could not connect to a node for reading.")
       end
     end
 
     # Checkout a socket connected to a node with one of
     # the provided tags. If no such node exists, raise
     # an exception.
+    #
+    # NOTE: will be available in driver release v2.0.
     def checkout_tagged(tags)
       sync_synchronize(:SH) do
         tags.each do |k, v|
@@ -372,14 +392,34 @@ module Mongo
     # Checkout a socket for writing (i.e., a primary node).
     def checkout_writer
       connect unless connected?
+      socket = get_socket_from_pool(@primary_pool)
 
+      if !socket
+        refresh
+        socket = get_socket_from_pool(@primary_pool)
+      end
+
+      if socket
+        socket
+      else
+        raise ConnectionFailure.new("Could not connect to primary node.")
+      end
+    end
+
+    def get_socket_from_pool(pool)
+      begin
         sync_synchronize(:SH) do
-        if @primary_pool
+          if pool
-          socket = @primary_pool.checkout
+            socket = pool.checkout
-          @sockets_to_pools[socket] = @primary_pool
+            @sockets_to_pools[socket] = pool
             socket
           end
         end
+
+      rescue ConnectionFailure => ex
+        log(:info, "Failed to checkout from #{pool} with #{ex.class}; #{ex.message}")
+        return nil
+      end
     end
 
     # Checkin a socket used for reading.
@@ -397,8 +437,12 @@ module Mongo
     end
 
     def checkin(socket)
+      sync_synchronize(:SH) do
         if pool = @sockets_to_pools[socket]
           pool.checkin(socket)
+        elsif socket
+          socket.close
+        end
       end
     end
   end

lib/mongo/util/logging.rb

@@ -2,7 +2,7 @@ module Mongo
   module Logging
 
     # Log a message with the given level.
-    def log(level, message)
+    def log(level, msg)
       return unless @logger
       case level
         when :debug then

lib/mongo/util/node.rb

@@ -20,6 +20,10 @@ module Mongo
     end
     alias :== :eql?
 
+    def close
+      self.socket.close if self.socket
+    end
+
     def host_string
       address
     end

lib/mongo/util/pool.rb

@@ -52,7 +52,8 @@ module Mongo
     end
 
     def close
-      @sockets.each do |sock|
+      @connection_mutex.synchronize do
+        (@sockets - @checked_out).each do |sock|
           begin
             sock.close
           rescue IOError => ex
@@ -64,6 +65,7 @@ module Mongo
         @pids.clear
         @checked_out.clear
       end
+    end
 
     def inspect
       "#<Mongo::Pool:0x#{self.object_id.to_s(16)} @host=#{@host} @port=#{port} " +
@@ -188,7 +190,7 @@ module Mongo
       if @pids[socket] != Process.pid
          @pids[socket] = nil
          @sockets.delete(socket)
-         socket.close
+         socket.close if socket
          checkout_new_socket
       else
         @checked_out << socket

lib/mongo/util/pool_manager.rb

@@ -23,31 +23,29 @@ module Mongo
       @members = members
     end
 
-    # Ensure that the view of the replica set is current by
-    # running the ismaster command and checking to see whether
-    # we've connected to all known nodes. If not, automatically
-    # connect to these unconnected nodes. This is handy when we've
-    # connected to a replica set with no primary or when a secondary
-    # node comes up after we've connected.
-    #
-    # If we're connected to nodes that are no longer part of the set,
-    # remove these from our set of secondary pools.
-    def update_required?(hosts)
-      if !@refresh_node || !@refresh_node.set_config
-        begin
-          @refresh_node = get_valid_seed_node
-        rescue ConnectionFailure
-          warn "Could not refresh config because no valid seed node was available."
-          return
-        end
-      end
-
-      hosts != @refresh_node.node_list
-    end
-
     private
 
     def initialize_data
+      begin
+        if @primary_pool
+          @primary_pool.close
+        end
+
+        if @secondary_pools
+          @secondary_pools.each do |pool|
+            pool.close
+          end
+        end
+
+        if @members
+          @members.each do |member|
+            member.close
+          end
+        end
+
+        rescue ConnectionFailure
+      end
+
       @primary = nil
       @primary_pool = nil
       @read_pool = nil

test/replica_sets/refresh_test.rb

@@ -6,6 +6,10 @@ require 'benchmark'
 class ReplicaSetRefreshTest < Test::Unit::TestCase
   include Mongo
 
+  def setup
+    @conn = nil
+  end
+
   def teardown
     RS.restart_killed_nodes
     @conn.close if @conn
@@ -98,7 +102,6 @@ class ReplicaSetRefreshTest < Test::Unit::TestCase
   end
 
   def test_adding_and_removing_nodes
-    puts "ADDING AND REMOVING"
     @conn = ReplSetConnection.new([RS.host, RS.ports[0]], [RS.host, RS.ports[1]],
       [RS.host, RS.ports[2]], :refresh_interval => 2, :auto_refresh => true)
 

test/tools/repl_set_manager.rb

@@ -21,7 +21,7 @@ class ReplSetManager
     @config     = {"_id" => @name, "members" => []}
     @durable    = opts.fetch(:durable, false)
     @path       = File.join(File.expand_path(File.dirname(__FILE__)), "data")
-    @oplog_size = opts.fetch(:oplog_size, 512)
+    @oplog_size = opts.fetch(:oplog_size, 32)
     @tags = [{"dc" => "ny", "rack" => "a", "db" => "main"},
              {"dc" => "ny", "rack" => "b", "db" => "main"},
              {"dc" => "sf", "rack" => "a", "db" => "main"}]