The total number of tickets in the system should be guaranteed not to exceed Integer.MAX_VALUE.

[thinkhy]

Run MyTester.LotterySchedulerVAR3, hit the error:

[ThreadState.getEffectivePriority] holder thread: main (#0) Size: 1
[LotteryQueue.pickNextThread] Thread: main (#0) Priority: 1

java.lang.IllegalArgumentException
at java.util.Random.nextInt(Random.java:236)
at nachos.threads.LotteryScheduler$LotteryQueue.pickNextThread(LotteryScheduler.java:92)
at nachos.threads.PriorityScheduler$PriorityQueue.nextThread(PriorityScheduler.java:196)
at nachos.threads.KThread.runNextThread(KThread.java:351)
at nachos.threads.KThread.sleep(KThread.java:264)
at nachos.threads.KThread.finish(KThread.java:211)
at nachos.threads.KThread.runThread(KThread.java:163)
at nachos.threads.KThread.access$000(KThread.java:30)
at nachos.threads.KThread$1.run(KThread.java:150)
at nachos.machine.TCB.threadroot(TCB.java:240)
at nachos.machine.TCB.access$100(TCB.java:25)
at nachos.machine.TCB$1.run(TCB.java:93)
at java.lang.Thread.run(Thread.java:738)

[thinkhy]

Thread: Child thread 84 (#86)     Priority: 536870911
Thread: Child thread 85 (#87)     Priority: 536870911
Thread: Child thread 86 (#88)     Priority: 536870911
Thread: Child thread 87 (#89)     Priority: 536870911
Thread: Child thread 88 (#90)     Priority: 536870911
Thread: Child thread 89 (#91)     Priority: 536870911
Thread: Child thread 90 (#92)     Priority: 536870911
Thread: Child thread 91 (#93)     Priority: 536870911
Thread: Child thread 92 (#94)     Priority: 536870911
Thread: Child thread 93 (#95)     Priority: 536870911
Thread: Child thread 94 (#96)     Priority: 536870911
Thread: Child thread 95 (#97)     Priority: 536870911
Thread: Child thread 96 (#98)     Priority: 536870911
Thread: Child thread 97 (#99)     Priority: 536870911
Thread: Child thread 98 (#100)    Priority: 536870911
Thread: Child thread 99 (#101)    Priority: 536870911
*******************
[ThreadState.getEffectivePriority] holder thread: Child thread 0 (#2) Size: 1
[ThreadState.getEffectivePriority] holder thread: Child thread 0 (#2)
[ThreadState.getEffectivePriority] holder thread: main (#0) Size: 1
[ThreadState.getEffectivePriority] holder thread: main (#0)
[ThreadState.getEffectivePriority] waitQueue priority: 0
[LotteryQueue.getEffectivePriority] controlled thread: main (#0) priority: 1
[ThreadState.getEffectivePriority] waitQueue priority: 1
[LotteryQueue.pickNextThread] Thread: Child thread 0 (#2)   Priority: 536870912
[ThreadState.getEffectivePriority] holder thread: Child thread 1 (#3) Size: 0
[LotteryQueue.pickNextThread] Thread: Child thread 1 (#3)   Priority: 536870911
[ThreadState.getEffectivePriority] holder thread: Child thread 2 (#4) Size: 0
[LotteryQueue.pickNextThread] Thread: Child thread 2 (#4)   Priority: 536870911
[ThreadState.getEffectivePriority] holder thread: Child thread 3 (#5) Size: 0
[LotteryQueue.pickNextThread] Thread: Child thread 3 (#5)   Priority: 536870911
[ThreadState.getEffectivePriority] holder thread: Child thread 4 (#6) Size: 0
[LotteryQueue.pickNextThread] Thread: Child thread 4 (#6)   Priority: 536870911

java.lang.ArithmeticException: Integer overflow
        at nachos.threads.LotteryScheduler.safeAdd(LotteryScheduler.java:185)
        at nachos.threads.LotteryScheduler$LotteryQueue.pickNextThread(LotteryScheduler.java:89)
        at nachos.threads.PriorityScheduler$PriorityQueue.nextThread(PriorityScheduler.java:196)
        at nachos.threads.KThread.runNextThread(KThread.java:351)
        at nachos.threads.KThread.sleep(KThread.java:264)
        at nachos.threads.KThread.join(KThread.java:317)
        at nachos.threads.MyTester.LotterySchedulerVAR3(MyTester.java:375)
        at nachos.threads.MyTester.TestLotteryScheduler(MyTester.java:271)
        at nachos.threads.MyTester.selfTest(MyTester.java:24)
        at nachos.threads.ThreadedKernel.selfTest(ThreadedKernel.java:53)
        at nachos.userprog.UserKernel.selfTest(UserKernel.java:57)
        at nachos.ag.AutoGrader.run(AutoGrader.java:153)
        at nachos.ag.AutoGrader.start(AutoGrader.java:50)
        at nachos.machine.Machine$1.run(Machine.java:64)
        at nachos.machine.TCB.threadroot(TCB.java:240)
        at nachos.machine.TCB.start(TCB.java:123)
        at nachos.machine.Machine.main(Machine.java:63)

[thinkhy]

Add a interface "safeAdd" in LotteryScheduler class:

    /**
     * @B22A
     * Detect and prevent integer overflow for plus of two integers
     *
     * @param   left        left value of integer
     * @param   right       right value of integer
     *
     * @return  a integer, sum of left and right value
     */
    static final int safeAdd(int left, int right)                       /* @B22A */
                 throws ArithmeticException {                           /* @B22A */

     if (right > 0 ? left > Integer.MAX_VALUE - right                   /* @B22A */
               : left < Integer.MIN_VALUE - right) {                    /* @B22A */
        /* throw new ArithmeticException("Integer overflow");                    */
         return Integer.MAX_VALUE;                                      /* @B22A */
     }                                                                  /* @B22A */

     return left + right;                                               /* @B22A */
    }

Then use safeAdd to perform add operation for calculation of tickets