This method generates a new lock each time it steps into. What does this lock do? 这个方法每次进来都是一把新的lock, 这个加锁起到了什么作用?

[jiahut]

double-cache/v4/src/main/java/com/cn/dc/cache/DoubleCache.java

Line 50 in a182bc4

ReentrantLock lock = new ReentrantLock();