util: Add WriteBatchInspector to inspect WriteBatch

[mapleFU]

Hi, here I add a tool for inspecting WriteBatch, and using it for debugging

[mapleFU]

@PragmaTwice @git-hulk

I20221103 15:03:19.033007 40160 replication.cc:903] LogData(3 6)Put(�__namespace
�7Ok/d��AA?���������, 4373)PutCF(1, �__namespace
7Ok, �/d��AA?�������������������)
I20221103 15:03:19.033021 40160 replication.cc:903] LogData(3 6)Put(�__namespace
�7Ok/d��AA?���������, 4374)PutCF(1, �__namespace
7Ok, �/d��AA?�������������������)
I20221103 15:03:19.033035 40160 replication.cc:903] LogData(3 6)Put(�__namespace
�7Ok/d��AA?���������, 4375)PutCF(1, �__namespace
7Ok, �/d��AA?�������������������)
I20221103 15:03:19.033063 40160 replication.cc:903] LogData(3 6)Put(�__namespace
�7Ok/d��AA?���������, 4376)PutCF(1, �__namespace
7Ok, �/d��AA?�������������������)
I20221103 15:03:19.033077 40160 replication.cc:903] LogData(3 6)Put(�__namespace
�7Ok/d��AA?���������, 4377)PutCF(1, �__namespace
7Ok, �/d��AA?�������������������)

After inpecting hook, I think WriteBatch::Handler may works well, because program still coredump on InternalKey

[git-hulk]

cool, the batch looks correct, it may be caused by the uninitialized value. Can have a look at #1068

[mapleFU]

cool, the batch looks correct, it may be caused by the uninitialized value. Can have a look at #1068

Ok, the handler is pasted from rocksdb's TestHandler. It was used by rocksdb internal, so I need to copy it here. Should I just close the pull request or add WriteBatchInspector to our codebase?

[git-hulk]

@mapleFU I think we can keep this PR, coz it can make the batch debug easier.

[mapleFU]

@git-hulk update and making it as a tool

[mapleFU]

@git-hulk I think it's ready to be merged now

[git-hulk]

@git-hulk I think it's ready to be merged now

OK, will take a look soon.

[caipengbo]

Should we write some notes to explain why the file was introduced and what the motivation was. Otherwise other developers might wonder what the file was for.

[mapleFU]

Updated now

[tanruixiang]

I noticed that batch_debugger.h was migrated from Rocksdb, and I don't really know if there are other specifications when there are multiple Copyrights. Do you think the current copyright notice is reasonable? @tisonkun

[mapleFU]

I noticed that batch_debugger.h was migrated from Rocksdb, and I don't really know if there are other specifications when there are multiple Copyrights. Do you think the current copyright notice is reasonable?

A sample is https://github.com/facebook/rocksdb/blob/main/db/table_cache.h#L1-L8

[tisonkun]

if there are other specifications when there are multiple Copyrights

@tanruixiang in our NOTICE file there is an entry about RocksDB dependency, and RocksDB supports downstream use under the Apache License 2.0 - so basically, it won't hurt.

But we can improve the copyright info layout and add an original link here. @mapleFU if you'd like to, refer to:

https://github.com/apache/incubator-kvrocks/blob/77f37d5f88b205883de56196820a48ab1349d9d6/tests/tcl/tests/unit/expire.tcl#L21-L22

.. or I'll update it after this patch is merged. It's not a blocker, anyway.

[mapleFU]

But we can improve the copyright info layout and add an original link here.

@tisonkun updated, PTAL

[tisonkun]

@mapleFU it seems that we don't use this Inspector in other code?

That said, if you'd like to debug, you add the code snippet as documented?

[mapleFU]

That said, if you'd like to debug, you add the code snippet as documented?

Yes, maybe user can receive raw bytes from remote and using this to parse the input @tisonkun

[tisonkun]

Merging...