Hi, Daniel Qian Are you talking about the asynchronous problem with the @SagaStart and @Compensable methods on the Omega side? I think this is a typical long transaction scene.
Alpha based on Actor model has implemented asynchronous processing of Omega and Alpha, The event sent to Alpha needs to ensure that all child transactions have been executed before sending SagaEndedEvent or SagaAbortedEvent. Lei Zhang > 在 2019年7月20日，下午9:49，Daniel Qian <[email protected]> 写道： > > After look into SCB-163, SCB-1385 and SCB-1386 I have some thoughts on Saga > involved in async invocation. > Current implementation is basically based on sync invocation, there are > some assumption: > > 1. When @SagaStart method returns, the Saga finished. > 2. When @Compensable method returns/throws exception, the Local Tx > succeeds/failed. > 3. When compensationMethod returns, the Local Tx is compensated. > > Even if considering what SCB-100 provided: > > 1. Add @OmegaContextAware annotation enabling > java.util.concurrent.Executor inject OmegaConext into threads it > manages/spawns > 2. Make OmegaContext use InheritableThreadLocal field let child thread > inherit parent thread's Local Tx info > > There are still some limitations: > > 1. @OmegaContextAware is only viable if you use spring framework > 2. @OmegaContextAware and OmegaContext's InheritableThreadLocal field > assuming that the calling thread or initator thread has Local Tx info. > > > What if user code use producer-consumer pattern in which > InheritableThreadLocal can't work? > What if user code use a thread scheduling library which we cannot use > @OmegaContextAware,RxJava and Reactor, for example? > I think we could provide some low-level APIs that user code can manualy > starts/ends Saga and Local Tx, something like below: > > TxContext context = omega.startSaga(); > TxContext subTxContext = omega.startTx(TxContext parentTxContext); > omega.endTx(TxContext); > omega.abortTx(TxContext); > omega.abortSaga(TxContext); > omega.endSaga(TxContext); > > TxContext is just a immutable dto like this: > > public class TxContext { > private final String globalTxId; > private final String localTxId; > } > > Above is a just a rough idea. So any thoughts? > -- > Daniel Qian > > 博客：https://segmentfault.com/u/chanjarster > github：https://github.com/chanjarster
