code: protected function logImpl($level, $message, array $context = array())
      {
          if (! $this->levelHasReached($level)) {
              return;
          }
          
          if ($this->isRotationNeeded()) {
              unlink($this->file);
          }
          
          $ms = $this->getMessage($level, $message, $context);
          
          $fos = new FileOutputStream($this->file, true);
          $fos->write($ms);
          $fos->flush();
          $fos->close();
      }
docs: This function provides the real logging function.
  
  First the log file size is checked.
  When the maximum size has reached, the file will be overwritten.
  Otherwise the log string is appended.
  
  @param integer $level
  The arbitrary level
  @param string $message
  The message to log
  @param array $context
  The context of logging