Concurrency Unit Test Final Version

From ExtremeProgrammingChallengeFourteenTheBug

---

import java.util.*;

public class BoundedBuffer {

    synchronized
void put(Object x) throws InterruptedException {
    while ( occupied == buffer.length ) {
wait();
    }
    /***/ TestBB.doSleep();
    notify();
    /***/ TestBB.doSleep();
    ++occupied;
    putAt %= buffer.length;
    buffer[putAt++] = x;
}

synchronized
Object take() throws InterruptedException {
    while ( occupied == 0 ) {
wait();
    }
    /***/ TestBB.doSleep();
    notify();
    --occupied;
    takeAt %= buffer.length;
    return buffer[takeAt++];
}

private Object[] buffer = new Object[1];
private int putAt, takeAt, occupied;

}

class TestBB extends Thread {

private static final int slow = 10;

private static int[]c1sleeps = {0,slow};
private static int[]c2sleeps = {0,0};
private static int[]p1sleeps = {0,slow*2,slow*2};
private static int[]p2sleeps = {0,0,0};

private static BoundedBuffertheBB = new BoundedBuffer();
private static Hashtablethreads = new Hashtable();

public static void main(String[] args) throws Throwable {
    int pass = 0;
    int fail = 0;
    for (int i=0; i< 50; i++) {
if (doTest()) {
    System.out.println("Fail.");
    fail++;
} else {
    System.out.println("Pass.");
    pass++;
}
    }
    System.out.println("Slow is "+slow+", false pass:"+pass+", fail:"+fail);
}

public static boolean doTest() throws Throwable {
    theBB = new BoundedBuffer();
    c1sleeps[0] = 0;
    c2sleeps[0] = 0;
    p1sleeps[0] = 0;
    p2sleeps[0] = 0;
    TestBB c1 = new TestBB("c1",c1sleeps) {
    public void run() {
    try {
    theBB.take();
    }
    catch (InterruptedException ie) {}
    }
    };
    TestBB c2 = new TestBB("c2",c2sleeps) {
    public void run() {
    try {
theBB.take();
    }
    catch (InterruptedException ie) {}
    }
    };
    TestBB p1 = new TestBB("p1",p1sleeps) {
    public void run() {
    try {
    theBB.put("A");
    }
    catch (InterruptedException ie) {}
    }
    };
    TestBB p2 = new TestBB("p2",p2sleeps) {
    public void run() {
    try {
    theBB.put("B");
    }
    catch (InterruptedException ie) {}
    }
    };
    c1.start();
    Thread.sleep(slow);
    c2.start();
    Thread.sleep(slow);
    p1.start();
    Thread.sleep(slow);
    p2.start();
    Thread.sleep(300+(slow*10));
    if (p2.isAlive()) {
    System.out.println("Liveness problem detected.");
    return true;
    }
    else return false;
}

public TestBB(String name,int[] sleeps) {
    super(name);
threads.put(this,sleeps);
}

public static void doSleep() {
int[] sleepsForThread = (int[])threads.get(Thread.currentThread());
if (sleepsForThread != null) {
int current = 1+(sleepsForThread[0] % (sleepsForThread.length-1));
sleepsForThread[0]++;
try {
Thread.sleep(sleepsForThread[current]);
}
catch(InterruptedException ie) {}
}
}

}