code: function(lastOne) {
      if (buffer.length >= bufferSize || (lastOne && buffer.length > 0)) {
        debug('writing', buffer.length, 'changes to the backup file');
        var b = { docs: buffer.splice(0, bufferSize), batch: batch };
        logStream.write(':t batch' + batch + ' ' + JSON.stringify(b.docs) + '\n');
        ee.emit('changes', batch);
        batch++;
      }
    }
docs: send documents ids to the queue in batches of bufferSize + the last batch