Spring Integration DSL：如何建立单线程缓存通道？

Question

I have the following flow config:

@Bean
public IntegrationFlow setupDatabaseFlow() {
    return IntegrationFlows.from(pubSubDatabaseRabbitOutput)
          // WHAT CHANNEL
            .handle((p, h) -> databaseActivator.recordToDatabase(p, h))
            .get();
}

and I am willing to insert in "WHAT CHANNEL" place some channel, that is

• caching
• single-threaded
• running in separate thread

What would be the best channel specification to use here?

Answer 1

Not sure what is the use-case, but that can be achieved with the QueueChannel and PollingConsumer with the fixedDelay policy.

1. QueueChannel uses queue buffer (persistent or in-memory) to keep messages until they are consumed. A-la cache in your terms.

2. The PollingConsumer does the poll from the queue using TaskScheduler , therefore separate thread.

3. Using fixedDelay policy you ensure that the next polling task won't start until the previous has been finished. Therefore single-threaded model.

If you don't like to sleep in between polling task, and end up with the event-driven model, you can use fixedDelay(-1) , this way the next polling task won't sleep after the previous. The current polling task does block the thread until the value in the queue.

UPDATE

Some code on the matter:

.channel(c -> c.queue())
.<Object>handle((p, h) -> databaseActivator.recordToDatabase(p, h), 
            e -> e.poller(p -> p.fixedDelay(0).maxMessagesPerPoll(1)))