System Stability Index Calculator

 

I wrote a service stability tool class for computing systems:

 

/**
 *
 * @ClassName StabilityCalculator
 * @author kanpiaoxue
 * @version 1.0
 * @CreateTime 2018/01/15 21:20:06
 * @Description Stability Calculator
 *
 *              <pre>
 * System stability calculation formula (annual):
 * (100 - (failure minutes / total minutes of the year * 100)) %
 * (100 - (Failure minutes / (60 * 24 * 365) * 100)) %
 *              （100 - (40 / 525600 * 100)） % = 99.992389649923896%
 *              </pre>
 */
public class StabilityCalculator {

    private enum TimeUnit {
        YEAR(365), QUARTER(120), MONTH(31);
        private static final int MINUTES_OF_DAY = 60 * 24;
        private int days;

        private TimeUnit(int num) {
            this.days = num;
        }

        public int getMinutes() {
            return MINUTES_OF_DAY * days;
        }
    }

    public static void main(String[] args) {
        StabilityCalculator sc = new StabilityCalculator();
        // The expected system stability that can be achieved in one year is: 99.99%, and the maximum time allowed for problems is: 52.56 minutes
        sc.calculateErrorTime(99.99D, TimeUnit.YEAR);
        // Expected system stability that can be achieved in one quarter: 99.99%, the maximum time allowed for problems is: 17.28 minutes
        sc.calculateErrorTime(99.99D, TimeUnit.QUARTER);
        System.out.println("==========================================");
        // There is 40 minutes of system instability in a year, and the system stability that can be achieved is: 99.99%
        sc.calculateStabilityPercent(40, TimeUnit.YEAR);
        // There is 40 minutes of system instability in a quarter, and the system stability that can be achieved is: 99.98%
        sc.calculateStabilityPercent(40, TimeUnit.QUARTER);
    }

    /**
     *
     * @param expectedPercent expected stability percentage
     * @param timeUnit The time unit for statistics: year, quarter
     * @return the maximum system instability time (minutes) that can occur to achieve the desired stability percentage
     * @author kanpiaoxue
     * @CreateTime 2018/01/15 21:45:29
     * @Description Calculates the maximum system instability time (minutes) that can occur based on the desired stability percentage
     */
    public double calculateErrorTime(double expectedPercent, TimeUnit timeUnit) {
        double totalMinutes = timeUnit.getMinutes();
        double minutes = (100D - expectedPercent) / 100D * totalMinutes;
        System.out.println(String.format("[%s] expectedPercent:%s, the least required minutes:%s minutes",
                timeUnit, expectedPercent, minutes));
        return minutes;
    }

    /**
     *
     * @param errorDuration The duration of system instability (minutes)
     * @param timeUnit The time unit for statistics: year, quarter
     * @return desired stability percentage
     * @author kanpiaoxue
     * @CreateTime 2018/01/15 21:45:32
     * @Description Calculates the current system stability percentage based on the duration (minutes) of system instability
     */
    public double calculateStabilityPercent(int errorDuration, TimeUnit timeUnit) {
        double totalMinutes = timeUnit.getMinutes();
        double expectedPercent = (100D - (errorDuration / totalMinutes * 100D));
        System.out.println(String.format("[%s] errorDuration:%s minutes, stability percent:%s", timeUnit,
                errorDuration, expectedPercent));
        return expectedPercent;
    }

}