Ensure that the socket is always checked in after send_message_with_gle

Previously, unhandled exceptions could cause the driver to leave a pool
entry checked out indefinitely and would stall any other attempts from
the same thread to check out the item, as the orphaned socket was the
thread-affiliated socket.

Fix syntax to be 1.8-compatible

Author: cheald

lib/mongo/networking.rb

@@ -86,13 +86,15 @@ def send_message_with_gle(operation, message, db_name, log_message=nil, write_co
         sock = checkout_writer
         send_message_on_socket(packed_message, sock)
         docs, num_received, cursor_id = receive(sock, last_error_id)
-        checkin(sock)
       rescue ConnectionFailure, OperationFailure, OperationTimeout => ex
-        checkin(sock)
         raise ex
       rescue SystemStackError, NoMemoryError, SystemCallError => ex
         close
+        sock = nil
         raise ex
+      ensure
+        checkin(sock) if sock
+        sock = nil
       end
 
       if num_received == 1

test/functional/client_test.rb

@@ -519,7 +519,7 @@ def test_operation_timeout_with_active
   context "Socket pools" do
     context "checking out writers" do
       setup do
-        @con = standard_connection(:pool_size => 10, :pool_timeout => 10)
+        @con = standard_connection(:pool_size => 10, :pool_timeout => 2)
         @coll = @con[TEST_DB]['test-connection-exceptions']
       end
 
@@ -533,13 +533,42 @@ def test_operation_timeout_with_active
         end
       end
 
-      should "close the connection on send_message_with_gle for major exceptions" do
-        @con.stubs(:checkout_writer).raises(SystemStackError)
-        @con.stubs(:checkout_reader).raises(SystemStackError)
-        @con.expects(:close)
-        begin
-          @coll.insert({:foo => "bar"}, :w => 1)
-        rescue SystemStackError
+      context "with GLE" do
+        setup do
+          # Force this connection to use send_message_with_gle for these tests
+          @con.stubs(:use_write_command?).returns(false)
+        end
+
+        should "close the connection on send_message_with_gle for major exceptions" do
+          @con.stubs(:checkout_writer).raises(SystemStackError)
+          @con.stubs(:checkout_reader).raises(SystemStackError)
+          @con.expects(:close)
+          begin
+            @coll.insert({:foo => "bar"}, :w => 1)
+          rescue SystemStackError
+          end
+        end
+
+        should "release the connection on send_message_with_gle for connection exceptions" do
+          mock_writer = mock(:close => true)
+          mock_writer.expects(:read).raises(ConnectionFailure)
+          @con.expects(:send_message_on_socket)
+
+          @con.stubs(:checkout_writer).returns(mock_writer)
+          @con.expects(:checkin).with(mock_writer)
+          @coll.insert({:foo => "bar"}, :w => 1) rescue nil
+        end
+
+        should "release the connection on send_message_with_gle for all exceptions" do
+          mock_writer = mock()
+          mock_writer.expects(:read).raises(ArgumentError)
+          @con.expects(:send_message_on_socket)
+          @con.stubs(:checkout_writer).returns(mock_writer)
+          @con.expects(:checkin).with(mock_writer).once
+          begin
+            @coll.insert({:foo => "bar"}, :w => 1)
+          rescue ArgumentError
+          end
         end
       end