feat: Add spring mutli container support

[FullOfOrange]

Our team has a monolithic architecture with multiple teams working on different domains in one codebase.

Each domain is isolated using Spring's container technology and consists of several child containers under a parent container, each connecting to the database using a different Datasource.

In this case, there are times when we want transactions to cross between the different domains for convenience. Using the traditional SpringTransactionManager, if a child transaction is executed, the parent transaction may encounter a "No transaction in context" error.

This error is caused by the current transaction manager in the TransactionManager interface not being updated properly across configuration boundaries.

Our team tried to solve this problem using the Stack.

We created logic that pushes to Stack when each transaction is executed and pops when the transaction ends, and after a year of using it, we haven't seen too many cases where it's broken, so we thought we'd contribute.

The above code may still have the following issues.

1. If you run the transaction in a Container that doesn't use SpringTransactionManager, it may not handle the transaction properly.
2. it does not yet properly support Spring's Transaction Propagation policy.

There may be additional issues besides the above, but at the very least, you should be able to use multiple data sources in Spring.

[e5l]

Hey @FullOfOrange! Thanks for the PR! Could you please check the CI?

[e5l]

@Tapac, @bog-walk could you also take a look?

[FullOfOrange]

This is an inherent problem with using transaction { } in Spring, if it's an uninitialized transaction inside a Spring Container, it will use the last (or may be first) of the initialized Datasources.

In the case where CI failed, the problem was caused by use the embeddedTest2 database in TransactionManager.current(), of the newly added SpringMultiContainerTransactionTest.

So I tried to change the configuration to determine the transaction boundary and use it.

If there is no SpringMultiContainerTransactionTest, prev test will still success

[FullOfOrange]

This issue has been around since before this PR, and it seems hard to resolve since exposed managing the current transaction as a companion object.

[e5l]

lgtm

[bog-walk]

@FullOfOrange Thanks to you and your team for all the effort behind this PR!

Just a question and 1 comment:

• Out of curiosity, during the time that your team has been using this solution, has it ever been used alongside coroutines or suspend transactions, like newSuspendedTransaction()? If so, have you encountered any issues or takeaways from the experience?

[FullOfOrange]

@bog-walk Thanks for the review!

Our team doesn't have much experience with coroutines because we using the servlet stack.

When using coroutines, we had no problem using the same Datasource (I don't remember exactly, but I think we got around it by initializing the Transaction with propagation = Propagation.REQUIRES_NEW).

Unfortunately, I haven't used coroutine or newSuspendedTransaction across multiple Datasources, so I'm not sure what the issues are.

I'll do some testing and let you know in an issue or another PR.

[bog-walk]

@FullOfOrange The info is much appreciated, thank you.

Could you check the detek GH action that's failing please? You might need to add @Suppress("TooGenericExceptionCaught") if throw Error is unavoidable.

[bog-walk]

Hi @FullOfOrange , the action is unfortunately still failing. Please check the details for a breakdown of the detekt errors.