source: benchmark/mutexC/JavaThread.java @ b797d978

class Noop {
        // Simplistic low-quality Marsaglia Shift-XOR pseudo-random number generator.
        // Bijective
        // Cycle length for non-zero values is 4G-1.
        // 0 is absorbing and should be avoided -- fixed point.
        // The returned value is typically masked to produce a positive value.
        static volatile int Ticket = 0 ;

        public static int nextRandom( int x ) {
                if (x == 0) {
                        // reseed the PRNG
                        // Ticket is accessed infrequently and does not constitute a coherence hot-spot.
                        // Note that we use a non-atomic racy increment -- the race is rare and benign.
                        // If the race is a concern switch to an AtomicInteger.
                        // In addition accesses to the RW volatile global "Ticket"  variable are not
                        // (readily) predictable at compile-time so the JIT will not be able to elide
                        // nextRandom() invocations.
                        x = ++Ticket ;
                        if (x == 0) x = 1 ;
                }
                x ^= x << 6;
                x ^= x >>> 21;
                x ^= x << 7;
                return x ;
        }
}
class Monitor {
        private int x;
        public volatile Boolean go = false;
        public volatile Boolean go2 = false;
        public synchronized void call() {
                if ( x == 0 ) System.out.println(x);
                x = Noop.nextRandom( x );
        }
        Monitor() { x = Noop.nextRandom( x ); }
}
class T extends Thread {
        Monitor m;
        public void run() {
                m.go2 = true;
                while ( ! m.go );
                while ( m.go ) { m.call(); }
        }
        T( Monitor m ) { this.m = m; }
}
public class JavaThread {
        static int x = 2;

        static private long times = Long.parseLong("10000000");

        public static void call( Monitor m ) throws InterruptedException {
                x = Noop.nextRandom( x );
                m.go = true;
                //while ( ! m.go2 );
                for ( long i = 0; i < times; i += 1 ) {
                        m.call();
                        x = Noop.nextRandom( x );
                }
                m.go = false;
        }
        public static void InnerMain() throws InterruptedException {
                Monitor m = new Monitor();
                T t = new T( m );
                t.start();
                long start = System.nanoTime();
                call( m );
                long end = System.nanoTime();
                System.out.println( (end - start) / times );
                t.join();
        }
        public static void main( String[] args ) throws InterruptedException {
                if ( args.length > 2 ) System.exit( 1 );
                if ( args.length == 2 ) { times = Long.parseLong(args[1]); }

                for ( int i = Integer.parseInt("5"); --i >= 0 ; ) {
                        InnerMain();
                        // Thread.sleep(2000);  // 2 seconds
                        x = Noop.nextRandom( x );
                }
                if ( x == 0 ) System.out.println(x);
        }
}

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