Improve the code style by introducing macros

[git-hulk]

Followup code improvements mentioned in PR #2508. Currently, we check and return error if the status is not ok in many many places, which can be improved by introducing macros.

The naming candidates can be:

• RETURN_NOT_OK
• RETURN_IF_ERROR

and for converting the rocksdb status if there is an error:

• RETURN_NOT_OK_FROM_ROCKSDB
• RETURN_IF_ERR_FROM_ROCKSDB

Originally posted by @mapleFU in #2508 (review)

[git-hulk]

@AntiTopQuark Would you like to take this issue?

[AntiTopQuark]

@AntiTopQuark Would you like to take this issue?

I’d be happy to take on this issue. ：）

[PragmaTwice]

The first macro is duplicated with the current GET_OR_RET macro.

[PragmaTwice]

For the second I think it depends on the context, e.g. rocksdb::Status -> Status? rocksdb::Status -> rocksdb::Status?

We can extend GET_OR_RET for the latter, and the former doesn't require new macro.

[git-hulk]

For the second I think it depends on the context, e.g. rocksdb::Status -> Status? rocksdb::Status -> rocksdb::Status?

We can extend GET_OR_RET for the latter, and the former doesn't require new macro.

Yes, my bad. GET_OR_RET allows ignoring the return value, so the former one is unnecessary.