How to retry the request every hour for 5 attempts in rxjava and retrofit

Question

I am trying to figure out how i can resubscribe the same observable for every hour when we have got an error from server for 5 attempts.I know about retryWhen but really not able to understand how i can use it in my case.I am using retrofit for server calls and rxjava to subscribe.

Here is the method where i am making a call using retrofit.Please help with this.

@Override public Observable<Integer> uploadFileToServer(FileUploadData fileUploadData, File file) { // log.i(TAG, "uploadFileToServer"); FileUploadEndpoint fileUploadEndpoint = null; try { fileUploadEndpoint = retrofitServiceFactory.getService(FileUploadEndpoint.class); } catch (BaseUrlNotFoundException e) { e.printStackTrace(); // log.i(TAG, "uploadFileToServer" + e.getMessage()); return Observable.just(FileUploadConstants.EXCEPTION_FILE_UPLOAD); } // create RequestBody instance from file RequestBody requestFile = RequestBody.create(okhttp3.MultipartBody.FORM, file); // MultipartBody.Part is used to send also the actual file name MultipartBody.Part body = MultipartBody.Part.createFormData("uploadfile", file.getName(), requestFile); // add another part within the multipart request String descriptionString = "file upload"; RequestBody description = RequestBody.create( okhttp3.MultipartBody.FORM, descriptionString); Map<String, String> queryMap = new HashMap<>(); queryMap.put("SENDER", fileUploadData.getSender()); queryMap.put("SOURCE", fileUploadData.getSource()); queryMap.put("SCHEMEID", fileUploadData.getSchemeId()); queryMap.put("ISPROCESSINGREQ", "false"); queryMap.put("ISENCRYPTED", "true"); queryMap.put("UID", fileUploadData.getSchemeId()); queryMap.put("METADATA", fileUploadData.getMetaData()); final Observable<FileUploadResponse> requestObservable = fileUploadEndpoint.upload(queryMap, description, body); return requestObservable.map(new Function<FileUploadResponse, Integer>() { @Override public Integer apply(FileUploadResponse fileUploadResponse) throws Exception { if (fileUploadResponse != null) { int code = fileUploadResponse.getStatusCode(); switch (code) { case 100: return FileUploadConstants.FILE_UPLOAD_SUCCESSFUL; } } return FileUploadConstants.EXCEPTION_FILE_UPLOAD; } }).retryWhen(new Function<Observable<Throwable>, ObservableSource<?>>() { @Override public ObservableSource<?> apply(Observable<Throwable> throwableObservable) throws Exception { return throwableObservable.zipWith(Observable.range(1, 5), new BiFunction<Throwable, Integer, FileUploadResponse>() { @Override public FileUploadResponse apply(Throwable throwable, Integer integer) throws Exception { return null;//not able to write the logic :( } }); } }); } @Override public void setBaseUrl(String baseUrl) { retrofitServiceFactory.setBaseUrl(baseUrl); } private interface FileUploadEndpoint { @Multipart @POST("da/appupload/file") Observable<FileUploadResponse> upload(@QueryMap Map<String, String> additionValues, @Part("description") RequestBody description, @Part MultipartBody.Part file); }

Andrej Jurkin · Accepted Answer · 2017-01-25 11:23:09Z

Here's a recipe for you.

public class RetryWithDelay implements Func1<Observable<? extends Throwable>, Observable<?>> { private static final String TAG = "RetryWithDelay"; private static final int DEFAULT_RETRY_COUNT = 5; private static final int DEFAULT_RETRY_DELAY = 1000 * 60; private final int maxRetries; private final int retryDelayMillis; private int retryCount; public RetryWithDelay() { this.maxRetries = DEFAULT_RETRY_COUNT; this.retryDelayMillis = DEFAULT_RETRY_DELAY; this.retryCount = 0; } public RetryWithDelay(final int maxRetries, final int retryDelayMillis) { this.maxRetries = maxRetries; this.retryDelayMillis = retryDelayMillis; this.retryCount = 0; } @Override public Observable<?> call(Observable<? extends Throwable> attempts) { return attempts.flatMap(new Func1<Throwable, Observable<?>>() { @Override public Observable<?> call(Throwable throwable) { if (throwable instanceof HttpException) { LOGD(TAG, "Caught http exception."); } if (throwable instanceof IOException) { LOGD(TAG, "Network error"); } if (++retryCount < maxRetries) { // When this Observable calls onNext, the original // Observable will be retried (i.e. re-subscribed). return Observable.timer(retryDelayMillis, TimeUnit.MILLISECONDS); } // Max retries hit. Just pass the error along. return Observable.error(throwable); } }); } }

Then in your code use it like this

// Leave constructor empty for default values .retryWhen(new RetryWithDelay()); // Or setup different values // In this case retry 3 times, with 5s delay .retryWhen(new RetyryWithDelay(3, 5000));

Cool ! Thanks a lot dude. Can you tell me which case i can use the inner class with retryWhen , just to understand the concept.
Sorry, I've edited my post. It was a bit misleading. I was not right. You can achieve the same result in other ways. This is just the way I use. The point is that in retryWhen function you have to provide an observable which has to emmit onNext or onComplete to trigger a retry. And how do you deal with the logic behind that is entirely up to you.

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