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RxJava Retry Web Service Connection incrementally if there is Network Kind of Error.
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public class RetryWithDelay implements Func1<Observable<? extends Throwable>, Observable<?>> { | |
private int numberOfTry; | |
private int delay; | |
private int retryCount = 1; | |
private final TimeUnit timeUnit; | |
public RetryWithDelay(int numberOfTry, int delay, TimeUnit timeUnit) { | |
this.numberOfTry = numberOfTry; | |
this.delay = delay; | |
this.timeUnit = timeUnit; | |
} | |
@Override | |
public Observable<?> call(Observable<? extends Throwable> errors) { | |
return errors | |
.flatMap(error -> { | |
if(error instanceof IOException) { // Network Error | |
int delayFinal = delay * retryCount; | |
retryCount++; | |
if (retryCount <= numberOfTry+1) { | |
// You might want to notify UI with EventBus etc... with Retry duration | |
Log.d("RetryWithDelay"+" call()", "retryCount " + delayFinal); | |
return Observable.timer((long) delayFinal, timeUnit); | |
} else { | |
return Observable.error(error); // Let them go to onError() after few retries | |
} | |
}else{ // Http Error or other Unexpected Error | |
return Observable.error(error); // Let them go to onError() | |
} | |
}); | |
} | |
} |
Test
public class RetryWithDelayTest {
private boolean returnCorrectAnswer;
@Before
public void setUp() throws Exception {
returnCorrectAnswer = false;
}
@Before
public void tearDown() throws Exception {
returnCorrectAnswer = false;
}
@Test
public void retry_shouldRetryOneTimeAndFail() {
// Assign
TestObserver<String> testObserver = new TestObserver<>();
TestScheduler testScheduler = new TestScheduler();
// Act
createObservable()
.subscribeOn(testScheduler)
.retryWhen(new RetryWithDelay(1, 1, TimeUnit.SECONDS, testScheduler))
.subscribe(testObserver);
// Assert
testObserver.assertSubscribed();
testObserver.assertNoValues();
testObserver.assertNoErrors();
testScheduler.advanceTimeBy(1, TimeUnit.SECONDS);
testObserver.assertValueCount(0);
Assert.assertEquals(testObserver.errorCount(), 1);
testObserver.assertError(IOException.class);
testObserver.assertNotComplete();
}
@Test
public void retry_shouldRetryTwoTimesAndFail() {
// Assign
TestObserver<String> testObserver = new TestObserver<>();
TestScheduler testScheduler = new TestScheduler();
// Act
createObservable()
.retryWhen(new RetryWithDelay(2, 1, TimeUnit.SECONDS, testScheduler))
.subscribeOn(Schedulers.trampoline())
.subscribe(testObserver);
// Assert
testObserver.assertSubscribed();
testObserver.assertNoValues();
testObserver.assertNoErrors();
testScheduler.advanceTimeBy(3, TimeUnit.SECONDS);
testObserver.assertValueCount(0);
Assert.assertEquals(testObserver.errorCount(), 1);
testObserver.assertError(IOException.class);
testObserver.assertNotComplete();
}
@Test
public void retry_shouldRetryOneTimeAndSucceed() {
// Assign
TestObserver<String> testObserver = new TestObserver<>();
TestScheduler testScheduler = new TestScheduler();
// Act
createObservable()
.subscribeOn(testScheduler)
.retryWhen(new RetryWithDelay(1, 2, TimeUnit.SECONDS, testScheduler))
.subscribe(testObserver);
// Assert
testObserver.assertSubscribed();
testObserver.assertNoValues();
testObserver.assertNoErrors();
testScheduler.advanceTimeTo(1, TimeUnit.SECONDS);
testObserver.assertNoValues();
testObserver.assertNoErrors();
returnCorrectAnswer = true;
testScheduler.advanceTimeTo(2, TimeUnit.SECONDS);
testObserver.assertValueCount(1);
testObserver.assertNoErrors();
}
@Test
public void retry_shouldRetryTwoTimesAndSucceed() {
// Assign
TestObserver<String> testObserver = new TestObserver<>();
TestScheduler testScheduler = new TestScheduler();
// Act
createObservable()
.subscribeOn(testScheduler)
.retryWhen(new RetryWithDelay(2, 2, TimeUnit.SECONDS, testScheduler))
.subscribe(testObserver);
// Assert
testObserver.assertSubscribed();
testObserver.assertNoValues();
testObserver.assertNoErrors();
testScheduler.advanceTimeTo(2, TimeUnit.SECONDS);
testObserver.assertNoValues();
testObserver.assertNoErrors();
returnCorrectAnswer = true;
testScheduler.advanceTimeTo(6, TimeUnit.SECONDS);
testObserver.assertValueCount(1);
testObserver.assertNoErrors();
}
@Test
public void retry_shouldNotRetryAndShouldFailOnDifferentExceptions() {
// Assign
TestObserver testObserver = new TestObserver();
TestScheduler testScheduler = new TestScheduler();
// Act
Observable.create(e -> e.onError(new RuntimeException()))
.subscribeOn(testScheduler)
.retryWhen(new RetryWithDelay(1, 2, TimeUnit.SECONDS))
.subscribe(testObserver);
// Assert
testObserver.assertSubscribed();
testObserver.assertNoValues();
testObserver.assertNoErrors();
testScheduler.advanceTimeBy(1, TimeUnit.SECONDS); // Retry is after 2s, so no retry is called
testObserver.assertValueCount(0);
Assert.assertEquals(1, testObserver.errorCount());
testObserver.assertError(RuntimeException.class);
testObserver.assertNotComplete();
}
// Helper
private Observable<String> createObservable() {
return Observable.create(e -> {
System.out.println(returnCorrectAnswer);
if (returnCorrectAnswer)
e.onNext("Correct Answer");
else
e.onError(new IOException());
});
}
}
Screw this, use Coroutine and good-old while loop :D
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RxJava2: