GH-8609: Fix bug that cannot applied correctly TcpConnectorInterceptor

[kazuki43zoo]

Fixes #8609

• add getLastWrapper() in TcpConnectionSupport
• change to passed the instance that geted via getLastWrapper() instead of self instance to TcpSender#addNewConnection
• Changed to passed the self instance to addNewConnection instead of argument's connection

[artembilan]

I wonder what is wrong with my suggestion to fix TcpConnectionInterceptorSupport: #8609 (comment).

The test looks OK and I believe the outcome will be exactly the same with my fix.

[kazuki43zoo]

The difference is wrapped connection that passed to interceptor's addNewConnection method:

Your change is:

AbstractServerConnectionFactory#initializeConnection
  →  CharacterAppendingInterceptor2#registerSenders(TcpSendingMessageHandler)
        →  CharacterAppendingInterceptor1#registerSenders(CharacterAppendingInterceptor1)
             →  CharacterAppendingInterceptor1#registerSender(CharacterAppendingInterceptor1)
                  →  CharacterAppendingInterceptor1#addNewConnection(CharacterAppendingInterceptor1) ★★Difference★★
                       →  CharacterAppendingInterceptor2#addNewConnection(CharacterAppendingInterceptor1) ★★Difference★★
                            →  TcpSendingMessageHandler#addNewConnection(CharacterAppendingInterceptor2)

My change is:

AbstractServerConnectionFactory#initializeConnection
  →  CharacterAppendingInterceptor2#registerSenders(TcpSendingMessageHandler)
        →  CharacterAppendingInterceptor1#registerSenders(CharacterAppendingInterceptor1)
             →  CharacterAppendingInterceptor1#registerSender(CharacterAppendingInterceptor1)
                  →  CharacterAppendingInterceptor1#addNewConnection(CharacterAppendingInterceptor2) ★★Difference★★
                       →  CharacterAppendingInterceptor2#addNewConnection(CharacterAppendingInterceptor2) ★★Difference★★
                            →  TcpSendingMessageHandler#addNewConnection(CharacterAppendingInterceptor2)

I thought it would be better to pass the last wrapped connection to all interceptors, what do you think?

[artembilan]

Yeah... It would be better to not have any wrapping at all, but rather just a chain of interceptors injected into a Connection.
But that's fully different story.

Let's listener what @garyrussell has in his mind on the matter!
He is an author of this TCP/IP framework, so better to make the final decision counting on his opinion.

Thank you for the contribution anyway!

[garyrussell]

I thought it would be better to pass the last wrapped connection to all interceptors, what do you think?

My intuition is that an interceptor in the chain should only reference the next in the chain, not the outermost one.

So I prefer @artembilan 's approach.

[kazuki43zoo]

@garyrussell @artembilan
Thanks for your comment!! I will change the code by @artembilan 's approach!!

[kazuki43zoo]

@garyrussell @artembilan
I've changed the code by @artembilan 's approach, please review again when you have time! Thanks!

[artembilan]

... and cherry-picked to 6.0.x & 5.5.x.

@kazuki43zoo ,
thank you for contribution; looking forward for more!