Htykuut

There are two events - event1 and event2 which can call getA(), these two events could occur simultaneously and trigger getA. I don't want to call getA multiple times until it gets done. I am using isDisposed() to check if its still active and calling dispose() explicitly in doFinally and setting fetchADisposable as null . Is there a better way to do this ?

Disposable fetchADisposable;

public void getA() {

    fetchA() //returns Observable

            .doFinally(new Action() {

        fetchADisposable.dispose();

        fetchADisposable = null;

            }).subscribe() {

        @Override

        public void onSubscribe (Disposable d){

            fetchADisposable = d;

        }



        @Override

        public void onNext () {

        }



        @Override

        public void onError (Throwable e){

        }



        @Override

        public void onComplete () {

        }

    }

}



public void event1() {

    if (fetchADisposable == null || fetchADisposable.isDisposed()) {

        getA();

    }

}



public void event2() {

    if (fetchADisposable == null || fetchADisposable.isDisposed()) {

        getA();

    }

}

Your existing solution has race conditions. You really need queuing to take place so that the events are processed serially.

The serialization of processing can be done using a PublishSubject that is subscribed to once only (say in the constructor or in an initializer method). The code looks like:

final PublishSubject<Integer> subject = createSubject();



private static PublishSubject<Integer> createSubject() {

    PublishSubject<Integer> subject = PublishSubject.<Integer>create().serialized();

    subject.subscribe(subscriber);

}



public void getA() {

    subject.onNext(1);

}