Please, coorect me if I wrong in my conclusions about async work and give any suggestions how to make this work asynchronously.
This code performs setting result of calculations in grid cells. As I assume asynchronous work should display grid cells by portions. So if we have 8 cores as result we can see that 8 cells displayed and during some time another 8 and so on (in case if I set some time delay). But for now as result cells displaying become one by one.
Model:
public class ListRepository implements ListRepositoryInterface {
private final Integer insertValue = 1000000;
private HashMap<String, BaseUnit> unitMap = new HashMap<>();
@Inject
public ListRepository() {}
public PublishSubject<BaseUnit> exec(int inputNumber) {
PublishSubject<BaseUnit> subject = PublishSubject.create();
Observable<BaseUnit> observable = getListObservable(inputNumber)
.subscribeOn(Schedulers.computation())
.flatMap(resultList ->
Observable.fromIterable(resultList)
.flatMap(listElem ->
Observable.fromArray(ListOperationName.values())
.map(operationElem -> {
ListUnit unit = new ListUnit(operationElem, listElem, 0);
calculate(unit, listElem);
unitMap.put(unit.getViewId(), unit);
return unit;
})
)
);
observable.subscribe(subject);
return subject;
}
private Observable<ArrayList<List<Integer>>> getListObservable(int inputNumber) {
return Observable.fromCallable(() -> {
ArrayList<List<Integer>> list = new ArrayList<>();
Integer[] populatedArray = new Integer[inputNumber];
Arrays.fill(populatedArray, insertValue);
list.add(new ArrayList<>(Arrays.asList(populatedArray)));
list.add(new LinkedList<>(Arrays.asList(populatedArray)));
list.add(new CopyOnWriteArrayList<>(Arrays.asList(populatedArray)));
return list;
});
}
private void calculate(ListUnit unit, List<Integer> list) {
try {
TimeUnit.MILLISECONDS.sleep(50);
} catch (InterruptedException e) {
e.printStackTrace();
}
double start = getTime();
//noinspection SynchronizationOnLocalVariableOrMethodParameter
synchronized (list) {
switch (unit.getOperationName()) {
case ADD_FIRST:
list.add(0, insertValue);
break;
case ADD_MID:
list.add(list.size() / 2, insertValue);
break;
case ADD_LAST:
list.add(insertValue);
break;
case SEARCH:
//noinspection unused
boolean contains = list.contains(insertValue);
break;
case RM_FIRST:
list.remove(0);
break;
case RM_MID:
list.remove(list.size() / 2);
break;
case RM_LAST:
list.remove(list.size() - 1);
break;
}
}
unit.setTime(getTime() - start);
}
private double getTime() {
return System.nanoTime();
}
public HashMap<String, BaseUnit> getUnitMap() {
return unitMap;
}
}
Presenter:
public void calculate(int inputNumber) {
fragment.showAllProgressBars();
PublishSubject<BaseUnit> subject = repository.exec(inputNumber);
Disposable disposable = subject.observeOn(AndroidSchedulers.mainThread())
.subscribe(unit -> {
fragment.setCellText(unit.getViewId(), unit.getTimeString());
}, Throwable::printStackTrace);
}
UPD: now I made test example and trying to subscribe to subject correctly. If I use subject.onNext() it works asynchronously, but I assume this is wrong because it doesn't get to check subject.hasComplete() and get "true". See comments "TODO" below.
private void run() {
Log.d("APP", "INIT");
PublishSubject<String> subject = exec(1000000);
subject.observeOn(AndroidSchedulers.mainThread())
.subscribe(unit -> {
Log.d("STRING RESULT = ", unit);
if (subject.hasComplete()) {
//TODO: this condition should work if we use observable.subscribe(subject), not subject.onNext
Log.d("SUBJECT", "COMPLETED");
}
}, Throwable::printStackTrace);
}
private int insertValue = 1000000;
public PublishSubject<String> exec(int inputNumber) {
PublishSubject<String> subject = PublishSubject.create();
getListObservable(inputNumber)
.flatMap(resultList -> getOperationsObservable()
.flatMap(operationElem -> getResultListObservable(resultList)
.map(listElem ->
calculate(operationElem, listElem)
//TODO: should be smth like this, i.e. calculate.subscribe(subject)
// .subscribe(subject)
.subscribe(subject::onNext)
)
)
).subscribe();
return subject;
}
private Observable<ArrayList<List<Integer>>> getListObservable(int inputNumber) {
return Observable.fromCallable(() -> {
ArrayList<List<Integer>> list = new ArrayList<>();
Integer[] populatedArray = new Integer[inputNumber];
Arrays.fill(populatedArray, insertValue);
list.add(new ArrayList<>(Arrays.asList(populatedArray)));
list.add(new LinkedList<>(Arrays.asList(populatedArray)));
list.add(new CopyOnWriteArrayList<>(Arrays.asList(populatedArray)));
return list;
}).subscribeOn(Schedulers.computation());
}
private Observable<String> calculate(ListOperationName operationName, List<Integer> list) {
return Observable.fromCallable(() -> {
try {
TimeUnit.MILLISECONDS.sleep(100);
} catch (InterruptedException e) {
e.printStackTrace();
}
double start = getTime();
synchronized (list) {
switch (operationName) {
case ADD_FIRST:
list.add(0, insertValue);
break;
case ADD_MID:
list.add(list.size() / 2, insertValue);
break;
case ADD_LAST:
list.add(insertValue);
break;
case SEARCH:
//noinspection unused
boolean contains = list.contains(insertValue);
break;
case RM_FIRST:
list.remove(0);
break;
case RM_MID:
list.remove(list.size() / 2);
break;
case RM_LAST:
list.remove(list.size() - 1);
break;
}
}
return Double.toString(getTime() - start);
}).subscribeOn(Schedulers.newThread());
}
private Observable<ListOperationName> getOperationsObservable() {
return Observable.fromArray(ListOperationName.values());
}
private Observable<List<Integer>> getResultListObservable(ArrayList<List<Integer>> list) {
return Observable.fromIterable(list);
}
private double getTime() {
return System.nanoTime();
}
public enum ListOperationName {
ADD_FIRST,
ADD_MID,
ADD_LAST,
SEARCH,
RM_FIRST,
RM_MID,
RM_LAST;
}
Gradle:
dependencies {
implementation 'io.reactivex.rxjava3:rxandroid:3.0.0'
implementation 'io.reactivex.rxjava3:rxjava:3.0.4'
}
If I remove .subscribeOn(Schedulers.newThread()); from the calculate(...) method in your most recent example and make the following change to exec(...), I seem to get the desired parallelism.
public Observable<String> exec( int inputNumber )
{
return getListObservable( inputNumber )
.flatMap( resultList -> getOperationsObservable()
.flatMap( operationElem -> getResultListObservable( resultList )
.flatMap( listElem -> Observable.just( listElem )
.subscribeOn( Schedulers.computation() )
.flatMap( __ -> calculate( operationElem, listElem )))));
}
I removed PublishSubject - it seems redundant, you can just subscribe to the resulting Observable, no?