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46. StampedLock
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package com.diguage.truman.concurrent;
import org.junit.jupiter.api.Test;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadLocalRandom;
import java.util.concurrent.locks.StampedLock;
/**
* @author D瓜哥, https://www.diguage.com/
* @since 2020-03-16 23:15
*/
public class StampedLockTest {
@Test
public void test() {
StampedLock lock = new StampedLock();
Point point = new Point(lock);
ExecutorService executorService = Executors.newFixedThreadPool(10);
for (int i = 0; i < 1000; i++) {
executorService.execute(() -> {
ThreadLocalRandom random = ThreadLocalRandom.current();
point.move(random.nextDouble(100), random.nextDouble(100));
System.out.println("move point...");
});
executorService.execute(() -> {
double distance = point.distanceFromOrigin();
System.out.println("current distance = " + distance);
});
}
}
static class Point {
private volatile double x, y;
private final StampedLock lock;
public Point(StampedLock lock) {
this.lock = lock;
}
void move(double deltaX, double deltaxY) {
long stamp = lock.writeLock();
try {
x += deltaX;
y += deltaxY;
} finally {
lock.unlock(stamp);
}
}
double distanceFromOrigin() {
long stamp = lock.tryOptimisticRead();
double currentX = x, currentY = y;
if (!lock.validate(stamp)) {
stamp = lock.readLock();
try {
currentX = x;
currentY = y;
} finally {
lock.unlock(stamp);
}
}
return Math.sqrt(currentX * currentX + currentY * currentY);
}
}
}