RunContext.CURRENT.get().getTransaction() and ITransaction.CURRENT.get() mismatch

[imotsch]

When nesting multiple RunContext chains the return value of calling

• RunContext.CURRENT.get().getTransaction()
• ITransaction.CURRENT.get() is not consistent.

Also the copy algorithm regarding the RunContextm_transaction member is - by design and on purpose - different in

• RunContext.CURRENT.get().copy uses m_transaction=other.m_transcation
• RunContexts.coppyCurrent() uses m_transaction=ITransaction.CURRENT.get()

Discrepancy

1. Whenever RunContext chains are nested one should always use RunContexts.coppyCurrent() in order to pass the current ITransaction to the child run context.

​This major difference in functionality is not reflected in the implementation code and not obvious in the javadoc.

2. In particular when using the transaction scope REQUIRES_NEW this difference can have major impacts.

**RunContexts.empty**().withScope(REQUIRES_NEW).run{
  // RunContext.CURRENT.get().getTransaction() is null due to RunContexts.empty()
  // ITransaction.CURRENT.get() is tx1 since a new ITranscation was created.

  // nesting with copyCurrent
  **RunContexts.copyCurrent**().withScope(REQUIRED).run{
    // all fine, OK
    // RunContext.CURRENT.get().getTransaction() is tx1 as set by copyCurrent()
    // ITransaction.CURRENT.get() is tx1 since no new ITranscation was created.
  }

  // nesting with RunContext.copy
  **RunContext.CURRENT.get().copy**().withScope(REQUIRED).run{
    // NOK
    // RunContext.CURRENT.get().getTransaction() is null as set by copy() that uses the parent RunContext.m_transaction that is never set.
    // ITransaction.CURRENT.get() is a new transcation tx2 since a new ITranscation had to be created. This is not intuitive and not the expectation of the programmer.
  }
}

Improvements

1. The method RunContext.getTransaction() is only used internally by run context chains and should never be used by user code. --> Add javadoc and @Derecation marker to that method

2. On the static method RunContexts.copyCurrent and method RunContext.copy() --> Add javadoc to clarifiy the difference regarding transaction and what to use for nesting run context chains.

3. When using the scope REQUIRES_NEW at build time of a RunContext once the chain with thread locals is applied in TransactionProcessor#runTxRequiresNew add a statement to set the current RunContext m_transaction to the correct value by RunContext.CURRENT.get().withTransaction(newTransaction)

[imotsch]

394954

[imotsch]

Fixed in 2024.2 https://github.com/eclipse-scout/scout.rt/pull/1177