How to set httpExecutor in Retrofit 2?

[dmarusic35]

Retrofit 1 has RestAdapter.Builder().setExecutors method which sets both httpExecutor and callbackExecutor while Retrofit 2 allows only to set callbackExecutor. Is there any way to set httpExecutor in Retrofit 2?

[JakeWharton]

Retrofit 2 uses OkHttp's async API (assuming you use Call.enqueue) which has manages its own threads per host for execution. OkHttp allows setting a Dispatcher which is the object the owns the threading, and can be created with an ExecutorService. if you just want to monitor the background execution, you can ask the OkHttpClient for its Dispatcher and then ask that instance for its ExecutorService.

[dmarusic35]

Thanks for quick reply

[JakeWharton]

Our of curiosity, are you just trying to monitor the background threads or
do you need to supply your own due some reason?

On Thu, Nov 5, 2015, 3:03 PM Damian Marusic notifications@github.com
wrote:

Thanks for quick reply

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#1259 (comment).

[dmarusic35]

I needed to supply my own Executor because when I run tests using Robolectric I want calls to be executed synchronously, on main thread. Manage to do it now by setting up Dispatcher, which is created by my implementation of ExecutorService, as you suggested.

[JakeWharton]

Ah, OK. Great!

On Thu, Nov 5, 2015, 4:01 PM Damian Marusic notifications@github.com
wrote:

I needed to supply my own Executor because when I run tests using
Robolectric I want calls to be executed synchronously, on main thread.
Manage to do it now by setting up Dispatcher, which is created by my
implementation of ExecutorService, as you suggested.

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#1259 (comment).

[pkhivesara]

@dmarusic35 Can you provide a snippet of how to go about creating the dispatcher and setting it up on the rest client?

[dmarusic35]

@pkhivesara I provide Dispatcher using Dagger. For app, I use default implementation:

@Provides
@Singleton
public Dispatcher provideDispatcher() {
    return new Dispatcher();
}

On the other hand, for tests, I use Dispatcher with my own implementation of ExecutorService (method execute(Runnable command) is where magic happens):

@Provides
@Singleton
public Dispatcher provideDispatcher() {
    // this dispatcher will ensure networking is done on the main thread
    return new Dispatcher(new SynchronousExecutorService());
}

private class SynchronousExecutorService implements ExecutorService {

    @Override
    public void shutdown() {

    }

    @NonNull
    @Override
    public List<Runnable> shutdownNow() {
        return null;
    }

    @Override
    public boolean isShutdown() {
        return false;
    }

    @Override
    public boolean isTerminated() {
        return false;
    }

    @Override
    public boolean awaitTermination(long timeout, TimeUnit unit) throws InterruptedException {
        return false;
    }

    @NonNull
    @Override
    public <T> Future<T> submit(Callable<T> task) {
        return null;
    }

    @NonNull
    @Override
    public <T> Future<T> submit(Runnable task, T result) {
        return null;
    }

    @NonNull
    @Override
    public Future<?> submit(Runnable task) {
        return null;
    }

    @NonNull
    @Override
    public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks) throws InterruptedException {
        return null;
    }

    @NonNull
    @Override
    public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit)
            throws InterruptedException {
        return null;
    }

    @NonNull
    @Override
    public <T> T invokeAny(Collection<? extends Callable<T>> tasks) throws InterruptedException, ExecutionException {
        return null;
    }

    @Override
    public <T> T invokeAny(Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit)
            throws InterruptedException, ExecutionException, TimeoutException {
        return null;
    }

    @Override
    public void execute(Runnable command) {
        command.run();
    }
}

And I just set provided dispatcher to OkHttpClient:

OkHttpClient.Builder okHttpClientBuilder = new OkHttpClient.Builder();
okHttpClientBuilder.dispatcher(dispatcher);
...