simplified connection pooling

lib/mongo/connection.rb

@@ -31,7 +31,7 @@ module Mongo
     STANDARD_HEADER_SIZE = 16
     RESPONSE_HEADER_SIZE = 20
 
-    attr_reader :logger, :size, :host, :port, :nodes, :sockets, :checked_out, :reserved_connections
+    attr_reader :logger, :size, :host, :port, :nodes, :sockets, :checked_out
 
     def slave_ok?
       @slave_ok
@@ -108,9 +108,6 @@ module Mongo
       @size      = options[:pool_size] || 1
       @timeout   = options[:timeout]   || 1.0
 
-      # Cache of reserved sockets mapped to threads
-      @reserved_connections = {}
-
       # Mutex for synchronizing pool access
       @connection_mutex = Monitor.new
 
@@ -293,49 +290,24 @@ module Mongo
       @host = @port = nil
       @sockets.clear
       @checked_out.clear
-      @reserved_connections.clear
     end
 
     private
 
     # Get a socket from the pool, mapped to the current thread.
     def checkout
-      #return @socket ||= checkout_new_socket if @size == 1
+      obtain_socket
-      if sock = @reserved_connections[Thread.current.object_id]
-        sock
-      else
-        sock = obtain_socket
-        @reserved_connections[Thread.current.object_id] = sock
-      end
-      sock
     end
 
     # Return a socket to the pool.
     def checkin(socket)
       @connection_mutex.synchronize do
-        @reserved_connections.delete Thread.current.object_id
         @checked_out.delete(socket)
         @queue.signal
       end
       true
     end
 
-    # Releases the connection for any dead threads.
-    # Called when the connection pool grows too large to free up more sockets.
-    def clear_stale_cached_connections!
-      keys = @reserved_connections.keys
-
-      Thread.list.each do |thread|
-        keys.delete(thread.object_id) if thread.alive?
-      end
-
-      keys.each do |key|
-        next unless @reserved_connections.has_key?(key)
-        checkin(@reserved_connections[key])
-        @reserved_connections.delete(key)
-      end
-    end
-
     # Adds a new socket to the pool and checks it out.
     #
     # This method is called exclusively from #obtain_socket;
@@ -366,10 +338,16 @@ module Mongo
     # pool size has not been exceeded. Otherwise, wait for the next
     # available socket.
     def obtain_socket
-      @connection_mutex.synchronize do
       connect_to_master if !connected?
-
+      start_time = Time.now
       loop do
+        if (Time.now - start_time) > 30
+            raise ConnectionTimeoutError, "could not obtain connection within " +
+              "#{@timeout} seconds. The max pool size is currently #{@size}; " +
+              "consider increasing it."
+        end
+
+        @connection_mutex.synchronize do
           socket = if @checked_out.size < @sockets.size
                      checkout_existing_socket
                    elsif @sockets.size < @size
@@ -377,26 +355,9 @@ module Mongo
                    end
 
           return socket if socket
-
+          wait
-          # Try to clear out any stale threads to free up some connections
+        end
-          clear_stale_cached_connections!
-          next if @checked_out.size < @sockets.size
-
-          # Otherwise, wait.
-          if wait
-            next
-          else
-
-            # Try to clear stale threads once more before failing.
-            clear_stale_cached_connections!
-            if @size == @sockets.size
-              raise ConnectionTimeoutError, "could not obtain connection within " +
-                "#{@timeout} seconds. The max pool size is currently #{@size}; " +
-                "consider increasing it."
       end
-          end  # if
-        end # loop
-      end # synchronize
     end
 
     if RUBY_VERSION >= '1.9'

test/threading/test_threading_large_pool.rb

@@ -6,7 +6,7 @@ class TestThreadingLargePool < Test::Unit::TestCase
 
   include Mongo
 
-  @@db = Connection.new('localhost', 27017, :pool_size => 50, :timeout => 15).db('ruby-mongo-test')
+  @@db = Connection.new('localhost', 27017, :pool_size => 50, :timeout => 1).db('ruby-mongo-test')
   @@coll = @@db.collection('thread-test-collection')
 
   def set_up_safe_data
@@ -25,7 +25,7 @@ class TestThreadingLargePool < Test::Unit::TestCase
   def test_safe_update
     set_up_safe_data
     threads = []
-    100.times do |i|
+    1000.times do |i|
       threads[i] = Thread.new do
         if i % 2 == 0
           assert_raise Mongo::OperationFailure do
@@ -37,7 +37,7 @@ class TestThreadingLargePool < Test::Unit::TestCase
       end
     end
 
-    100.times do |i|
+    1000.times do |i|
       threads[i].join
     end
   end
@@ -45,7 +45,7 @@ class TestThreadingLargePool < Test::Unit::TestCase
   def test_safe_insert
     set_up_safe_data
     threads = []
-    100.times do |i|
+    1000.times do |i|
       threads[i] = Thread.new do
         if i % 2 == 0
           assert_raise Mongo::OperationFailure do
@@ -57,7 +57,7 @@ class TestThreadingLargePool < Test::Unit::TestCase
       end
     end
 
-    100.times do |i|
+    1000.times do |i|
       threads[i].join
     end
   end

test/unit/connection_test.rb

@@ -12,11 +12,6 @@ class ConnectionTest < Test::Unit::TestCase
     db = Object.new
   end
 
-  # Make a few methods public for these tests.
-  class Mongo::Connection
-    public :checkin, :checkout, :clear_stale_cached_connections!
-  end
-
   context "Initialization: " do
 
     context "given a single node" do
@@ -60,79 +55,5 @@ class ConnectionTest < Test::Unit::TestCase
       assert_equal 2500, @conn.port
     end
   end
-
-  context "Connection pooling: " do
-    setup do
-      TCPSocket.stubs(:new).returns(new_mock_socket)
-      @conn = Connection.new('localhost', 27107, :connect => false,
-                                   :pool_size => 3)
-
-      admin_db = new_mock_db
-      admin_db.expects(:command).returns({'ok' => 1, 'ismaster' => 1})
-      @conn.expects(:[]).with('admin').returns(admin_db)
-      @conn.connect_to_master
-    end
-
-    should "check out a new connection" do
-      socket = @conn.checkout
-      assert @conn.reserved_connections.keys.include?(Thread.current.object_id)
-    end
-
-    context "with multiple threads" do
-      setup do
-        @thread1 = Object.new
-        @thread2 = Object.new
-        @thread3 = Object.new
-        @thread4 = Object.new
-
-        Thread.stubs(:current).returns(@thread1)
-        @socket1 = @conn.checkout
-        Thread.stubs(:current).returns(@thread2)
-        @socket2 = @conn.checkout
-        Thread.stubs(:current).returns(@thread3)
-        @socket3 = @conn.checkout
-      end
-
-      should "add each thread to the reserved pool" do
-        assert @conn.reserved_connections.keys.include?(@thread1.object_id)
-        assert @conn.reserved_connections.keys.include?(@thread2.object_id)
-        assert @conn.reserved_connections.keys.include?(@thread3.object_id)
-      end
-
-      should "only add one socket per thread" do
-        @conn.reserved_connections.values do |socket|
-          assert [@socket1, @socket2, @socket3].include?(socket)
-        end
-      end
-
-      should "check out all sockets" do
-        assert_equal @conn.sockets.size, @conn.checked_out.size
-        @conn.sockets.each do |sock|
-          assert @conn.checked_out.include?(sock)
-        end
-      end
-
-      should "raise an error if no more sockets can be checked out" do
-        # This can't be tested with mock threads.
-        # Will test in integration tests.
-      end
-
-      context "when releasing dead threads" do
-        setup do
-          @thread1.expects(:alive?).returns(false)
-          @thread2.expects(:alive?).returns(true)
-          @thread3.expects(:alive?).returns(true)
-          Thread.expects(:list).returns([@thread1, @thread2, @thread3])
-          @conn.clear_stale_cached_connections!
-        end
-
-        should "return connections for dead threads" do
-          assert !@conn.checked_out.include?(@socket1)
-          assert_nil @conn.reserved_connections[@thread1.object_id]
-        end
-      end
-
-    end
-  end
 end