feat(iterator):Auto commit mode for applying log iterator

[1294566108]

Motivation:

Auto commit mode for applying log iterator

Modification:

issue link is here.

Result:

[killme2008]

@1294566108 I think we should call commit in Iterator#next(). It means committing the state machine before getting the next element, just like we don't have auto-commit mode but we want to commit on every log:

while(it.hasNext()) {
   byte [] data = it.getData();
   it.commit();
   it.next();   
}

It looks like we don't need the variable lastCommit, commit many times for the same log index has no side effects.

[killme2008]

@1294566108 Please sign the CLA and format the code by mvn compile:compile.

[1294566108]

@1294566108 Please sign the CLA and format the code by mvn compile:compile.

Okay, I have recompiled and submitted it

[killme2008]

@1294566108 You have to sign the CLA http://cla.sofastack.tech/

If not, we can't merge this PR. thank you.

[1294566108]

@1294566108 You have to sign the CLA http://cla.sofastack.tech/

If not, we can't merge this PR. thank you.

之前似乎有签署过个人的CLA，刚刚又签了一次，请问还需要签署公司CLA吗

[killme2008]

@seeflood Hi, the new contributor's CLA state can't be updated again, please help to check it.