下面是相当于你的。我已经压力测试了一些与成千上万的线程并发访问它：它的工作原理，与一些重试（循环）执行（显然，你永远不能证明正确性在并发世界中的测试）。

You could make it a little shorter with the code below which is equivalent to yours. I have stress tested it a little with thousands of threads accessing it concurrently: it works as expected, with a number of retries (loops) being performed (obviously, you can never prove correctness with testing in the concurrent world).

public void insertOrReplace(String key, String value) {
    for (;;) {
        String oldValue = concurrentMap.putIfAbsent(key, value);
        if (oldValue == null)
            return;

        final String newValue = recalculateNewValue(oldValue, value);
        if (concurrentMap.replace(key, oldValue, newValue))
            return;
    }
}