def __get_uptime_ms(self):
        """Returns the number of milliseconds the system has been up.

        @return: The number of milliseconds the system has been up.
        @rtype: int
        """
        if self._boot_time_ms is None:
            # We read /proc/uptime once to get the current boot time.
            uptime_file = None
            try:
                uptime_file = open("/proc/uptime", "r")
                # The first number in the file is the number of seconds since
                # boot time.  So, we just use that to calculate the milliseconds
                # past epoch.
                self._boot_time_ms = int(time.time()) * 1000 - int(float(uptime_file.readline().split()[0]) * 1000.0)
            finally:
                if uptime_file is not None:
                    uptime_file.close()

        # Calculate the uptime by just taking current time and subtracting out
        # the boot time.
        return int(time.time()) * 1000 - self._boot_time_ms
dataset/ETHPy150Open scalyr/scalyr-agent-2/scalyr_agent/builtin_monitors/linux_process_metrics.py/StatReader.__get_uptime_ms/original