anchor.diff:  }
   
   /// Responds with the updates test to the [request].
  -_updateTest(request) {
  +_updatesTest(request) {
     var queries = _parseInt(request.uri.queryParameters['queries']).clamp(1, 500);
  -  var worlds = new List<World>(queries);
  -  Future.wait(new List.generate(queries, (index) {
  -    return _connectionPool.connect().then((connection) {
  -      return connection.query(
  -              'SELECT id, randomNumber FROM world WHERE id = @id;',
  -              { 'id': _RANDOM.nextInt(_WORLD_TABLE_SIZE) + 1 })
  -          .toList()
  -          .then((rows) {
  -            //
  -            // The benchmark's constraints tell us there is exactly one row.
  -            //
  -            var row = rows[0];
  -            worlds[index] = new World(row[0], row[1]);
  -          })
  -          .whenComplete(() { connection.close(); });
  -    });
  -  }, growable: false)).then((_) {
  -    Future.wait(new List.generate(queries, (int index) {
  -      var world = worlds[index];
  -      world.randomNumber = _RANDOM.nextInt(_WORLD_TABLE_SIZE) + 1;
  -      return _connectionPool.connect().then((connection) {
  -        return connection.execute(
  +  Future.wait(new List.generate(queries, (_) {
  +    return _queryRandom()
  +        .then((world) {
  +          world.randomNumber = _RANDOM.nextInt(_WORLD_TABLE_SIZE) + 1;
  +          return _connectionPool.connect().then((connection) {
  +            return connection.execute(
                   'UPDATE world SET randomNumber = @randomNumber WHERE id = @id;',
                   { 'randomNumber': world.randomNumber, 'id': world.id })
  -            .whenComplete(() { connection.close(); });
  -      });
  -    }, growable: false)).then((_) { _sendJson(request, worlds); });
  -  });
  +                .whenComplete(() { connection.close(); });
  +          }).then((_) => world);
  +        });
  +  }, growable: false))
  +      .then((worlds) => _sendJson(request, worlds));
   }
   
   /// Responds with the plaintext test to the [request].
  
positive.code:   _sendJson(request, { 'message': 'Hello, World!' });
  }
  
  /// Responds with the database query test to the [request].
  _dbTest(request) {
    var queries = _parseInt(request.uri.queryParameters['queries']).clamp(1, 500);
    var worlds = new List<World>(queries);
    Future.wait(new List.generate(queries, (index) {
      return _connectionPool.connect().then((connection) {
        return connection.query(
                'SELECT id, randomNumber FROM world WHERE id = @id;',
                { 'id': _RANDOM.nextInt(_WORLD_TABLE_SIZE) + 1 })
            .toList()
            .then((rows) {
              //
              // The benchmark's constraints tell us there is exactly one row.
              //
              var row = rows[0];
              worlds[index] = new World(row[0], row[1]);
            })
            .whenComplete(() { connection.close(); });
      });
    }, growable: false)).then((_) { _sendJson(request, worlds); });
  }
  
  /// Responds with the fortunes test to the [request].
  _fortunesTest(request) {
    var fortunes = [];
    _connectionPool.connect().then((connection) {
      return connection.query('SELECT id, message FROM fortune;')
          .toList()
          .then((rows) {
            for (var row in rows) {
              fortunes.add(new Fortune(row[0], row[1]));
            }
          })
          .whenComplete(() { connection.close(); });
    }).then((_) {
      fortunes.add(new Fortune(0, 'Additional fortune added at request time.'));
      fortunes.sort();
      _sendHtml(request, _fortunesTemplate.renderString({
  
negative.code:     request.response.headers.contentType = type;
    }
    if (response != null) {
      var data = encodeUtf8(response);
      request.response.contentLength = data.length;
      request.response.add(data);
    } else {
      request.response.contentLength = 0;
    }
    request.response.close();
  }
  