Commit transaction after early return

[sondrele]

Ever since #57 and transaction was made inline the API has allowed for non-label returns from a transaction block.

This is problematic because it allows for uncommitted transactions.

The provided test case demonstrate the problem:

    @Test
    fun transactionWithNonLabeledReturnGetsCommitted() {
        fun insertAndReturn(session: Session, name: String) {
            session.transaction { tx ->
                tx.run(queryOf(insert, name, Date()).asUpdate)
                // Non-labeled return
                return
            }
        }

        using(sessionOf(testDataSource)) { session ->
            insertAndReturn(session, "Chris")
        }

        using(sessionOf(testDataSource)) { session ->
            val membersCount = session.single(queryOf("select count(*) as count from members")) { row ->
                row.int("count")
            }
            assertEquals(1, membersCount)
        }
    }

Note that changing insertAndReturn to return@transaction works as expected, but since transaction is inline the return statement will exit the insertAndReturn function before the underlying connection gets committed.

A potential solution could have been to mark operation as crossinline (like so inline fun <A> transaction(crossinline operation: (TransactionalSession) -> A): A), but this would break support for coroutines within the transaction block.

I altered the implementation to commit the transaction as part of the finally block instead and it seams to work for this example.

[seratch]

Thanks for your contribution! I will release a new version tomorrow