com.azure.core.util.polling

Class PollerFlux<T,U>

java.lang.Object

reactor.core.publisher.Flux<AsyncPollResponse<T,U>>

com.azure.core.util.polling.PollerFlux<T,U>

Type Parameters:

T - The type of poll response value.

U - The type of the final result of long running operation.

All Implemented Interfaces:

org.reactivestreams.Publisher<T>, CorePublisher<AsyncPollResponse<T,U>>

public final class PollerFlux<T,U>
extends Flux<AsyncPollResponse<T,U>>

A Flux that simplifies the task of executing long running operations against an Azure service. A subscription to PollerFlux initiates a long running operation and polls the status until it completes.

Code samples

Instantiating and subscribing to PollerFlux

 LocalDateTime timeToReturnFinalResponse = LocalDateTime.now().plus(Duration.ofMillis(800));
 
 // Create poller instance
 PollerFlux<String, String> poller = new PollerFlux<>(Duration.ofMillis(100),
     (context) -> Mono.empty(),
     // Define your custom poll operation
     (context) ->  {
         if (LocalDateTime.now().isBefore(timeToReturnFinalResponse)) {
             System.out.println("Returning intermediate response.");
             return Mono.just(new PollResponse<>(LongRunningOperationStatus.IN_PROGRESS,
                     "Operation in progress."));
         } else {
             System.out.println("Returning final response.");
             return Mono.just(new PollResponse<>(LongRunningOperationStatus.SUCCESSFULLY_COMPLETED,
                     "Operation completed."));
         }
     },
     (activationResponse, context) -> Mono.error(new RuntimeException("Cancellation is not supported")),
     (context) -> Mono.just("Final Output"));
 
 // Listen to poll responses
 poller.subscribe(response -> {
     // Process poll response
     System.out.printf("Got response. Status: %s, Value: %s%n", response.getStatus(), response.getValue());
 });
 // Do something else
 
 

Asynchronously wait for polling to complete and then retrieve the final result

 LocalDateTime timeToReturnFinalResponse = LocalDateTime.now().plus(Duration.ofMinutes(5));
 
 // Create poller instance
 PollerFlux<String, String> poller = new PollerFlux<>(Duration.ofMillis(100),
     (context) -> Mono.empty(),
     (context) ->  {
         if (LocalDateTime.now().isBefore(timeToReturnFinalResponse)) {
             System.out.println("Returning intermediate response.");
             return Mono.just(new PollResponse<>(LongRunningOperationStatus.IN_PROGRESS,
                     "Operation in progress."));
         } else {
             System.out.println("Returning final response.");
             return Mono.just(new PollResponse<>(LongRunningOperationStatus.SUCCESSFULLY_COMPLETED,
                     "Operation completed."));
         }
     },
     (activationResponse, context) -> Mono.just("FromServer:OperationIsCancelled"),
     (context) -> Mono.just("FromServer:FinalOutput"));
 
 poller.take(Duration.ofMinutes(30))
         .last()
         .flatMap(asyncPollResponse -> {
             if (asyncPollResponse.getStatus() == LongRunningOperationStatus.SUCCESSFULLY_COMPLETED) {
                 // operation completed successfully, retrieving final result.
                 return asyncPollResponse
                         .getFinalResult();
             } else {
                 return Mono.error(new RuntimeException("polling completed unsuccessfully with status:"
                         + asyncPollResponse.getStatus()));
             }
         }).block();
 
 

Block for polling to complete and then retrieve the final result

 AsyncPollResponse<String, String> terminalResponse = pollerFlux.blockLast();
 System.out.printf("Polling complete. Final Status: %s", terminalResponse.getStatus());
 if (terminalResponse.getStatus() == LongRunningOperationStatus.SUCCESSFULLY_COMPLETED) {
     String finalResult = terminalResponse.getFinalResult().block();
     System.out.printf("Polling complete. Final Status: %s", finalResult);
 }
 

Asynchronously poll until poller receives matching status

 final Predicate<AsyncPollResponse<String, String>> isComplete = response -> {
     return response.getStatus() != LongRunningOperationStatus.IN_PROGRESS
         && response.getStatus() != LongRunningOperationStatus.NOT_STARTED;
 };
 
 pollerFlux
     .takeUntil(isComplete)
     .subscribe(completed -> {
         System.out.println("Completed poll response, status: " + completed.getStatus());
     });
 

Asynchronously cancel the long running operation

 LocalDateTime timeToReturnFinalResponse = LocalDateTime.now().plus(Duration.ofMinutes(5));
 
 // Create poller instance
 PollerFlux<String, String> poller = new PollerFlux<>(Duration.ofMillis(100),
     (context) -> Mono.empty(),
     (context) ->  {
         if (LocalDateTime.now().isBefore(timeToReturnFinalResponse)) {
             System.out.println("Returning intermediate response.");
             return Mono.just(new PollResponse<>(LongRunningOperationStatus.IN_PROGRESS,
                     "Operation in progress."));
         } else {
             System.out.println("Returning final response.");
             return Mono.just(new PollResponse<>(LongRunningOperationStatus.SUCCESSFULLY_COMPLETED,
                     "Operation completed."));
         }
     },
     (activationResponse, context) -> Mono.just("FromServer:OperationIsCancelled"),
     (context) -> Mono.just("FromServer:FinalOutput"));
 
 // Asynchronously wait 30 minutes to complete the polling, if not completed
 // within in the time then cancel the server operation.
 poller.take(Duration.ofMinutes(30))
         .last()
         .flatMap(asyncPollResponse -> {
             if (!asyncPollResponse.getStatus().isComplete()) {
                 return asyncPollResponse
                         .cancelOperation()
                         .then(Mono.error(new RuntimeException("Operation is cancelled!")));
             } else {
                 return Mono.just(asyncPollResponse);
             }
         }).block();
 
 

Constructor Summary

Constructors

Constructor and Description
PollerFlux(Duration pollInterval, Function<PollingContext<T>,Mono<T>> activationOperation, Function<PollingContext<T>,Mono<PollResponse<T>>> pollOperation, BiFunction<PollingContext<T>,PollResponse<T>,Mono<T>> cancelOperation, Function<PollingContext<T>,Mono<U>> fetchResultOperation) Creates PollerFlux.

Method Summary

Modifier and Type	Method and Description
static <T,U> PollerFlux<T,U>	create(Duration pollInterval, Function<PollingContext<T>,Mono<PollResponse<T>>> activationOperation, Function<PollingContext<T>,Mono<PollResponse<T>>> pollOperation, BiFunction<PollingContext<T>,PollResponse<T>,Mono<T>> cancelOperation, Function<PollingContext<T>,Mono<U>> fetchResultOperation) Creates PollerFlux.
static <T,U> PollerFlux<T,U>	error(Exception ex) Creates a PollerFlux instance that returns an error on subscription.
SyncPoller<T,U>	getSyncPoller()
PollerFlux<T,U>	setPollInterval(Duration pollInterval) Sets the poll interval for this poller.
void	subscribe(CoreSubscriber<? super AsyncPollResponse<T,U>> actual)

Methods inherited from class reactor.core.publisher.Flux

all, any, as, blockFirst, blockFirst, blockLast, blockLast, buffer, buffer, buffer, buffer, buffer, buffer, buffer, buffer, buffer, buffer, buffer, bufferTimeout, bufferTimeout, bufferTimeout, bufferTimeout, bufferUntil, bufferUntil, bufferUntilChanged, bufferUntilChanged, bufferUntilChanged, bufferWhen, bufferWhen, bufferWhile, cache, cache, cache, cache, cache, cache, cancelOn, cast, checkpoint, checkpoint, checkpoint, collect, collect, collectList, collectMap, collectMap, collectMap, collectMultimap, collectMultimap, collectMultimap, collectSortedList, collectSortedList, combineLatest, combineLatest, combineLatest, combineLatest, combineLatest, combineLatest, combineLatest, combineLatest, combineLatest, concat, concat, concat, concat, concatDelayError, concatDelayError, concatDelayError, concatDelayError, concatMap, concatMap, concatMapDelayError, concatMapDelayError, concatMapDelayError, concatMapIterable, concatMapIterable, concatWith, concatWithValues, contextWrite, contextWrite, count, create, create, defaultIfEmpty, defer, deferContextual, deferWithContext, delayElements, delayElements, delaySequence, delaySequence, delaySubscription, delaySubscription, delaySubscription, delayUntil, dematerialize, distinct, distinct, distinct, distinct, distinctUntilChanged, distinctUntilChanged, distinctUntilChanged, doAfterTerminate, doFinally, doFirst, doOnCancel, doOnComplete, doOnDiscard, doOnEach, doOnError, doOnError, doOnError, doOnNext, doOnRequest, doOnSubscribe, doOnTerminate, elapsed, elapsed, elementAt, elementAt, empty, error, error, error, expand, expand, expandDeep, expandDeep, filter, filterWhen, filterWhen, first, first, firstWithSignal, firstWithSignal, firstWithValue, firstWithValue, flatMap, flatMap, flatMap, flatMap, flatMapDelayError, flatMapIterable, flatMapIterable, flatMapSequential, flatMapSequential, flatMapSequential, flatMapSequentialDelayError, from, fromArray, fromIterable, fromStream, fromStream, generate, generate, generate, getPrefetch, groupBy, groupBy, groupBy, groupBy, groupJoin, handle, hasElement, hasElements, hide, ignoreElements, index, index, interval, interval, interval, interval, join, just, just, last, last, limitRate, limitRate, limitRequest, log, log, log, log, log, log, map, materialize, merge, merge, merge, merge, merge, merge, mergeDelayError, mergeOrdered, mergeOrdered, mergeOrdered, mergeOrderedWith, mergeSequential, mergeSequential, mergeSequential, mergeSequential, mergeSequential, mergeSequential, mergeSequentialDelayError, mergeSequentialDelayError, mergeSequentialDelayError, mergeWith, metrics, name, never, next, ofType, onAssembly, onAssembly, onBackpressureBuffer, onBackpressureBuffer, onBackpressureBuffer, onBackpressureBuffer, onBackpressureBuffer, onBackpressureBuffer, onBackpressureBuffer, onBackpressureDrop, onBackpressureDrop, onBackpressureError, onBackpressureLatest, onErrorContinue, onErrorContinue, onErrorContinue, onErrorMap, onErrorMap, onErrorMap, onErrorResume, onErrorResume, onErrorResume, onErrorReturn, onErrorReturn, onErrorReturn, onErrorStop, onTerminateDetach, or, parallel, parallel, parallel, publish, publish, publish, publish, publishNext, publishOn, publishOn, publishOn, push, push, range, reduce, reduce, reduceWith, repeat, repeat, repeat, repeat, repeatWhen, replay, replay, replay, replay, replay, replay, retry, retry, retryWhen, sample, sample, sampleFirst, sampleFirst, sampleTimeout, sampleTimeout, scan, scan, scanWith, share, shareNext, single, single, singleOrEmpty, skip, skip, skip, skipLast, skipUntil, skipUntilOther, skipWhile, sort, sort, startWith, startWith, startWith, subscribe, subscribe, subscribe, subscribe, subscribe, subscribe, subscribe, subscribeOn, subscribeOn, subscriberContext, subscriberContext, subscribeWith, switchIfEmpty, switchMap, switchMap, switchOnFirst, switchOnFirst, switchOnNext, switchOnNext, tag, take, take, take, takeLast, takeUntil, takeUntilOther, takeWhile, then, then, thenEmpty, thenMany, timed, timed, timeout, timeout, timeout, timeout, timeout, timeout, timeout, timestamp, timestamp, toIterable, toIterable, toIterable, toStream, toStream, toString, transform, transformDeferred, transformDeferredContextual, using, using, usingWhen, usingWhen, window, window, window, window, window, window, window, windowTimeout, windowTimeout, windowUntil, windowUntil, windowUntil, windowUntilChanged, windowUntilChanged, windowUntilChanged, windowWhen, windowWhile, windowWhile, withLatestFrom, zip, zip, zip, zip, zip, zip, zip, zip, zip, zip, zip, zip, zip, zipWith, zipWith, zipWith, zipWith, zipWithIterable, zipWithIterable

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

PollerFlux

public PollerFlux(Duration pollInterval,
                  Function<PollingContext<T>,Mono<T>> activationOperation,
                  Function<PollingContext<T>,Mono<PollResponse<T>>> pollOperation,
                  BiFunction<PollingContext<T>,PollResponse<T>,Mono<T>> cancelOperation,
                  Function<PollingContext<T>,Mono<U>> fetchResultOperation)

Creates PollerFlux.

Parameters:

pollInterval - the polling interval

activationOperation - the activation operation to activate (start) the long running operation. This operation will be invoked at most once across all subscriptions. This parameter is required. If there is no specific activation work to be done then invocation should return Mono.empty(), this operation will be called with a new PollingContext.

pollOperation - the operation to poll the current state of long running operation. This parameter is required and the operation will be called with current PollingContext.

cancelOperation - a Function that represents the operation to cancel the long running operation if service supports cancellation. This parameter is required. If service does not support cancellation then the implementer should return Mono.error with an error message indicating absence of cancellation support. The operation will be called with current PollingContext.

fetchResultOperation - a Function that represents the operation to retrieve final result of the long running operation if service support it. This parameter is required and operation will be called current PollingContext. If service does not have an api to fetch final result and if final result is same as final poll response value then implementer can choose to simply return value from provided final poll response.

Method Detail

create

public static <T,U> PollerFlux<T,U> create(Duration pollInterval,
                                           Function<PollingContext<T>,Mono<PollResponse<T>>> activationOperation,
                                           Function<PollingContext<T>,Mono<PollResponse<T>>> pollOperation,
                                           BiFunction<PollingContext<T>,PollResponse<T>,Mono<T>> cancelOperation,
                                           Function<PollingContext<T>,Mono<U>> fetchResultOperation)

Creates PollerFlux. This create method differs from the PollerFlux constructor in that the constructor uses an activationOperation which returns a Mono that emits result, the create method uses an activationOperation which returns a Mono that emits PollResponse. The PollResponse holds the result. If the PollResponse from the activationOperation indicate that long running operation is completed then the pollOperation will not be called.

Type Parameters:

T - The type of poll response value.

U - The type of the final result of long running operation.

Parameters:

pollInterval - the polling interval

activationOperation - the activation operation to activate (start) the long running operation. This operation will be invoked at most once across all subscriptions. This parameter is required. If there is no specific activation work to be done then invocation should return Mono.empty(), this operation will be called with a new PollingContext.

pollOperation - the operation to poll the current state of long running operation. This parameter is required and the operation will be called with current PollingContext.

cancelOperation - a Function that represents the operation to cancel the long running operation if service supports cancellation. This parameter is required. If service does not support cancellation then the implementer should return Mono.error with an error message indicating absence of cancellation support. The operation will be called with current PollingContext.

fetchResultOperation - a Function that represents the operation to retrieve final result of the long running operation if service support it. This parameter is required and operation will be called current PollingContext. If service does not have an api to fetch final result and if final result is same as final poll response value then implementer can choose to simply return value from provided final poll response.

Returns:

PollerFlux

error

public static <T,U> PollerFlux<T,U> error(Exception ex)

Creates a PollerFlux instance that returns an error on subscription.

Type Parameters:

T - The type of poll response value.

U - The type of the final result of long running operation.

Parameters:

ex - The exception to be returned on subscription of this PollerFlux.

Returns:

A poller flux instance that returns an error without emitting any data.

See Also:

Mono.error(Throwable), Flux.error(Throwable)

setPollInterval

public PollerFlux<T,U> setPollInterval(Duration pollInterval)

Sets the poll interval for this poller. The new interval will be used for all subsequent polling operations including the subscriptions that are already in progress.

Parameters:

pollInterval - The new poll interval for this poller.

Returns:

The updated instance of PollerFlux.

Throws:

NullPointerException - if the pollInterval is null.

IllegalArgumentException - if the pollInterval is zero or negative.

subscribe

public void subscribe(CoreSubscriber<? super AsyncPollResponse<T,U>> actual)

Specified by:

subscribe in interface CorePublisher<AsyncPollResponse<T,U>>

Specified by:

subscribe in class Flux<AsyncPollResponse<T,U>>

getSyncPoller

public SyncPoller<T,U> getSyncPoller()

Returns:

a synchronous blocking poller.