Replace AtomicLong to long while ReentrantReadWriteLock is enough

[pifuant]

No description provided.

[pifuant]

@killme2008 @fengjiachun PTAL

[fengjiachun]

I think you are right, 'lastCommittedIndex' does not need to be AtomicLong, ReentrantReadWriteLock is enough, but I think, can you optimize it further?
replace ReentrantReadWriteLock with StampedLock, then getLastCommittedIndex() uses StampedLock#tryOptimisticRead() to read.

@killme2008 @pifuant PTAL

[killme2008]

Good catch! Yep, AtomicLong is not necessary here, it can be replaced by primitive long type.

I agree with @fengjiachun , use StampedLock is a better choice because getLastCommittedIndex is called so frequently that tryOptimisticRead will help.

[fengjiachun]

@pifuant

public long getLastCommittedIndex() {
        long stamp = stampedLock.tryOptimisticRead();
        long optimisticVal = this.lastCommittedIndex;
        if (stampedLock.validate(stamp)) {
            return optimisticVal;
        }
        stamp = stampedLock.readLock();
        try {
            return this.lastCommittedIndex;
        } finally {
            stampedLock.unlockRead(stamp);
        }
    }

[pifuant]

@killme2008 @fengjiachun PTAL

[fengjiachun]

@pifuant

1. long stamp -> final long stamp ? except on tryOptimisticRead()
2. stampedLock.unlock(stamp) -> stampedLock.unlockWrite(stamp) ？

[pifuant]

@fengjiachun PTAL

[killme2008]

👍

[fengjiachun]

@pifuant tks