使用 SynchronousQueue 与 ThreadPoolExecutor 实现同步行为

Question

我正在编写一个服务类，它应该有两种模式：同步和异步。

public class ProcessorImpl implements IProcessor {

    private final MyRepo repo;
    private final Jobrunner runner;
    private final boolean isAsync;


    private ExecutorService executorService;

    @ProcessorImpl
    public ProcessorImpl(final MyRepo repo,
                              final Jobrunner runner) {
        this(repo, runner, false);
    }

    public ProcessorImpl(final MyRepo repo,
                              final Jobrunner runner,
                              final boolean isAsync) {
        this.repo = repo;
        this.runner = runner;
        this.isAsync = isAsync;
    }

    @PostConstruct
    public void init() {
        if (isAsync) {          
            executorService = new ThreadPoolExecutor(1,1,60, TimeUnit.SECONDS, new LinkedBlockingQueue<>(50));
        } else {
            executorService = new ThreadPoolExecutor(1,1,60, TimeUnit.SECONDS, new SynchronousQueue<>());
        }
    }

    @Override
    public Response doAction(final Request request, final String id) {
        if (isAsync) {
            //submit task and return incomplete response with id
        } else {
            //submit task and get result and return response that is returned by Callable
        }
    }
}

切换由isAsync 标志驱动。

当同步时，我希望能够提交任务，从任务提交中获取完成的响应并使用它来构建Response 以返回。对于这种模式，我使用的是SynchronousQueue。

当异步模式开启时，只需提交任务并立即返回，响应不完整。对于这种模式，我使用LinkedBlockingQueue来等待队列中的任务。

关于同步模式，我有两个问题：

1. 如何获取结果并以同步方式给出响应？我不确定如何在这里使用Future。

2. 如果线程正在处理任务时另一个命令任务进来怎么办？会被拒绝吗？如何避免被拒绝？

对于一些代码示例的任何帮助将不胜感激。

谢谢

Answer 1

类似这样的：

public class SyncProcessorImpl {
    private final MyRepo repo;
    private final Jobrunner runner;

    public SyncProcessorImpl (final MyRepo repo, final Jobrunner runner) {
        this.repo = repo;
        this.runner = runner;
    }

    public Response doAction(final Request request, final String id) {
        // do all calculations directly and return complete response
    }
}

public class AsyncProcessorImpl extends SyncProcessorImpl {
    private ExecutorService executorService;

    public AsyncProcessorImpl(final MyRepo repo, final Jobrunner runner) {
        super(repo, runner);
        executorService = new ThreadPoolExecutor(1,1,60, TimeUnit.SECONDS, new LinkedBlockingQueue<>(50));
    }

    public Future<Response> doActionAsync(final Request request, final String id) {
        //submit task and return future that is returned by submit(Callable)
       return executorService.submit(()->super.doActionc(request, id));
    }
}