java - java AtomicInteger accumulateAndGet被应用(java AtomicInteger accumulateAndGet is applied)

Question

I have a Counter class that stores value as AtomicInteger.

(我有一个Counter类，将值存储为AtomicInteger。)

That class should be thread safe.

(该类应该是线程安全的。)

I have method boolean consume(int number) that should decrement counter and return true if counter >= number , and should not change counter and return false if counter < number

(我boolean consume(int number) ，该方法应减少counter并在counter >= number返回true ，并且不应更改counter并在counter < number返回false)

class Counter {
   AtomicInteger counter = new AtomicInteger(initialValue);

   boolean consume(int number) {
     counter.accumulateAndGet(number, (prev, next) -> {
            if (number <= prev) {
                return prev - number;
            } else {
                // not modify the previous number;
                return prev;
            }
        });
       return ???
   }
}

And I don't know if the function applied or not.

(而且我不知道该功能是否适用。)

I found the following solution

(我发现以下解决方案)

boolean consume(int number) {
    AtomicBoolean result = new AtomicBoolean(false);
    counter.accumulateAndGet(number, (prev, next) -> {
            if (number <= prev) {
                result.set(true);
                return prev - number;
                // function applied
            } else {
                result.set(false);
                // not modify the previous number;
                return prev;
            }
    });
    return result.get();
}

but javadoc of accumulateAndGet sais:

(但是accumulateAndGet javadoc说：)

The function should be side-effect-free, since it may be re-applied when attempted updates fail due to contention among threads.

(该函数应无副作用，因为当尝试更新由于线程间的争用而失败时，可以重新应用该函数。)

So, my solution has side effects.

(因此，我的解决方案有副作用。)

Is it safe to use?

(使用安全吗？)

If not, how can I get the same result?

(如果没有，我如何获得相同的结果？)

  ask by a3dsfcv translate from so

Answer 1

等待大神答复