io.reactivex.processors

Class ReplayProcessor<T>

java.lang.Object

io.reactivex.Flowable<T>

io.reactivex.processors.FlowableProcessor<T>

io.reactivex.processors.ReplayProcessor<T>

Type Parameters:

T - the value type

All Implemented Interfaces:

org.reactivestreams.Processor<T,T>, org.reactivestreams.Publisher<T>, org.reactivestreams.Subscriber<T>

public final class ReplayProcessor<T>
extends FlowableProcessor<T>

Replays events to Subscribers.

The ReplayProcessor can be created in bounded and unbounded mode. It can be bounded by size (maximum number of elements retained at most) and/or time (maximum age of elements replayed).

This Processor respects the backpressure behavior of its Subscribers (individually) but does not coordinate their request amounts towards the upstream (because there might not be any).

Note that Subscribers receive a continuous sequence of values after they subscribed even if an individual item gets delayed due to backpressure.

Example usage:

 ReplayProcessor<Object> processor = new ReplayProcessor<T>();
  processor.onNext("one");
  processor.onNext("two");
  processor.onNext("three");
  processor.onComplete();

  // both of the following will get the onNext/onComplete calls from above
  processor.subscribe(subscriber1);
  processor.subscribe(subscriber2);

   

Method Summary

Methods

Modifier and Type	Method and Description
static <T> ReplayProcessor<T>	create() Creates an unbounded ReplayProcessor.
static <T> ReplayProcessor<T>	create(int capacityHint) Creates an unbounded ReplayProcessor with the specified initial buffer capacity.
static <T> ReplayProcessor<T>	createWithSize(int maxSize) Creates a size-bounded ReplayProcessor.
static <T> ReplayProcessor<T>	createWithTime(long maxAge, java.util.concurrent.TimeUnit unit, Scheduler scheduler) Creates a time-bounded ReplayProcessor.
static <T> ReplayProcessor<T>	createWithTimeAndSize(long maxAge, java.util.concurrent.TimeUnit unit, Scheduler scheduler, int maxSize) Creates a time- and size-bounded ReplayProcessor.
java.lang.Throwable	getThrowable() Returns the error that caused the Subject to terminate or null if the Subject hasn't terminated yet.
T	getValue() Returns a single value the Subject currently has or null if no such value exists.
java.lang.Object[]	getValues() Returns an Object array containing snapshot all values of the Subject.
T[]	getValues(T[] array) Returns a typed array containing a snapshot of all values of the Subject.
boolean	hasComplete() Returns true if the subject has reached a terminal state through a complete event.
boolean	hasSubscribers() Returns true if the subject has subscribers.
boolean	hasThrowable() Returns true if the subject has reached a terminal state through an error event.
boolean	hasValue() Returns true if the subject has any value.
void	onComplete()
void	onError(java.lang.Throwable t)
void	onNext(T t)
void	onSubscribe(org.reactivestreams.Subscription s)
protected void	subscribeActual(org.reactivestreams.Subscriber<? super T> s) Operator implementations (both source and intermediate) should implement this method that performs the necessary business logic.

Methods inherited from class io.reactivex.processors.FlowableProcessor

toSerialized

Methods inherited from class io.reactivex.Flowable

all, amb, ambArray, ambWith, any, blockingFirst, blockingFirst, blockingForEach, blockingIterable, blockingIterable, blockingLast, blockingLast, blockingLatest, blockingMostRecent, blockingNext, blockingSingle, blockingSingle, blockingSubscribe, blockingSubscribe, blockingSubscribe, blockingSubscribe, blockingSubscribe, buffer, buffer, buffer, buffer, buffer, buffer, buffer, buffer, buffer, buffer, buffer, buffer, buffer, buffer, buffer, buffer, buffer, buffer, buffer, bufferSize, cache, cacheWithInitialCapacity, cast, collect, collectInto, combineLatest, combineLatest, combineLatest, combineLatest, combineLatest, combineLatest, combineLatest, combineLatest, combineLatest, combineLatest, combineLatest, combineLatest, combineLatest, combineLatestDelayError, combineLatestDelayError, combineLatestDelayError, combineLatestDelayError, combineLatestDelayError, combineLatestDelayError, compose, concat, concat, concat, concat, concat, concat, concatArray, concatArrayDelayError, concatArrayEager, concatArrayEager, concatDelayError, concatDelayError, concatDelayError, concatEager, concatEager, concatEager, concatEager, concatMap, concatMap, concatMapDelayError, concatMapDelayError, concatMapEager, concatMapEager, concatMapEagerDelayError, concatMapEagerDelayError, concatMapIterable, concatMapIterable, concatWith, contains, count, create, debounce, debounce, debounce, defaultIfEmpty, defer, delay, delay, delay, delay, delay, delay, delaySubscription, delaySubscription, delaySubscription, dematerialize, distinct, distinct, distinct, distinctUntilChanged, distinctUntilChanged, distinctUntilChanged, doAfterNext, doAfterTerminate, doFinally, doOnCancel, doOnComplete, doOnEach, doOnEach, doOnError, doOnLifecycle, doOnNext, doOnRequest, doOnSubscribe, doOnTerminate, elementAt, elementAt, elementAtOrError, empty, error, error, filter, first, firstElement, firstOrError, flatMap, flatMap, flatMap, flatMap, flatMap, flatMap, flatMap, flatMap, flatMap, flatMap, flatMap, flatMap, flatMapCompletable, flatMapCompletable, flatMapIterable, flatMapIterable, flatMapIterable, flatMapIterable, flatMapMaybe, flatMapMaybe, flatMapSingle, flatMapSingle, forEach, forEachWhile, forEachWhile, forEachWhile, fromArray, fromCallable, fromFuture, fromFuture, fromFuture, fromFuture, fromIterable, fromPublisher, generate, generate, generate, generate, generate, groupBy, groupBy, groupBy, groupBy, groupBy, groupJoin, hide, ignoreElements, interval, interval, interval, interval, intervalRange, intervalRange, isEmpty, join, just, just, just, just, just, just, just, just, just, just, last, lastElement, lastOrError, lift, map, materialize, merge, merge, merge, merge, merge, merge, merge, merge, mergeArray, mergeArray, mergeArrayDelayError, mergeArrayDelayError, mergeDelayError, mergeDelayError, mergeDelayError, mergeDelayError, mergeDelayError, mergeDelayError, mergeDelayError, mergeDelayError, mergeWith, never, observeOn, observeOn, observeOn, ofType, onBackpressureBuffer, onBackpressureBuffer, onBackpressureBuffer, onBackpressureBuffer, onBackpressureBuffer, onBackpressureBuffer, onBackpressureBuffer, onBackpressureBuffer, onBackpressureDrop, onBackpressureDrop, onBackpressureLatest, onErrorResumeNext, onErrorResumeNext, onErrorReturn, onErrorReturnItem, onExceptionResumeNext, onTerminateDetach, parallel, parallel, parallel, publish, publish, publish, publish, range, rangeLong, rebatchRequests, reduce, reduce, reduceWith, repeat, repeat, repeatUntil, repeatWhen, replay, replay, replay, replay, replay, replay, replay, replay, replay, replay, replay, replay, replay, replay, replay, replay, retry, retry, retry, retry, retry, retryUntil, retryWhen, safeSubscribe, sample, sample, sample, sample, sample, sample, scan, scan, scanWith, sequenceEqual, sequenceEqual, sequenceEqual, sequenceEqual, serialize, share, single, singleElement, singleOrError, skip, skip, skip, skipLast, skipLast, skipLast, skipLast, skipLast, skipLast, skipUntil, skipWhile, sorted, sorted, startWith, startWith, startWith, startWithArray, strict, subscribe, subscribe, subscribe, subscribe, subscribe, subscribe, subscribeOn, subscribeWith, switchIfEmpty, switchMap, switchMap, switchMapDelayError, switchMapDelayError, switchOnNext, switchOnNext, switchOnNextDelayError, switchOnNextDelayError, take, take, take, takeLast, takeLast, takeLast, takeLast, takeLast, takeLast, takeLast, takeLast, takeLast, takeUntil, takeUntil, takeWhile, test, test, test, throttleFirst, throttleFirst, throttleLast, throttleLast, throttleWithTimeout, throttleWithTimeout, timeInterval, timeInterval, timeInterval, timeInterval, timeout, timeout, timeout, timeout, timeout, timeout, timeout, timeout, timer, timer, timestamp, timestamp, timestamp, timestamp, to, toFuture, toList, toList, toList, toMap, toMap, toMap, toMultimap, toMultimap, toMultimap, toMultimap, toObservable, toSortedList, toSortedList, toSortedList, toSortedList, unsafeCreate, unsubscribeOn, using, using, window, window, window, window, window, window, window, window, window, window, window, window, window, window, window, window, window, window, window, withLatestFrom, withLatestFrom, withLatestFrom, withLatestFrom, withLatestFrom, withLatestFrom, zip, zip, zip, zip, zip, zip, zip, zip, zip, zip, zip, zip, zipArray, zipIterable, zipWith, zipWith, zipWith, zipWith

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.reactivestreams.Publisher

subscribe

Method Detail

create

@CheckReturnValue
public static <T> ReplayProcessor<T> create()

Creates an unbounded ReplayProcessor.

The internal buffer is backed by an ArrayList and starts with an initial capacity of 16. Once the number of items reaches this capacity, it will grow as necessary (usually by 50%). However, as the number of items grows, this causes frequent array reallocation and copying, and may hurt performance and latency. This can be avoided with the create(int) overload which takes an initial capacity parameter and can be tuned to reduce the array reallocation frequency as needed.

Type Parameters:

T - the type of items observed and emitted by the ReplayProcessor

Returns:

the created ReplayProcessor

create

@CheckReturnValue
public static <T> ReplayProcessor<T> create(int capacityHint)

Creates an unbounded ReplayProcessor with the specified initial buffer capacity.

Use this method to avoid excessive array reallocation while the internal buffer grows to accommodate new items. For example, if you know that the buffer will hold 32k items, you can ask the ReplayProcessor to preallocate its internal array with a capacity to hold that many items. Once the items start to arrive, the internal array won't need to grow, creating less garbage and no overhead due to frequent array-copying.

Type Parameters:

T - the type of items observed and emitted by the Subject

Parameters:

capacityHint - the initial buffer capacity

Returns:

the created subject

createWithSize

@CheckReturnValue
public static <T> ReplayProcessor<T> createWithSize(int maxSize)

Creates a size-bounded ReplayProcessor.

In this setting, the ReplayProcessor holds at most size items in its internal buffer and discards the oldest item.

When observers subscribe to a terminated ReplayProcessor, they are guaranteed to see at most size onNext events followed by a termination event.

If an observer subscribes while the ReplayProcessor is active, it will observe all items in the buffer at that point in time and each item observed afterwards, even if the buffer evicts items due to the size constraint in the mean time. In other words, once an Observer subscribes, it will receive items without gaps in the sequence.

Type Parameters:

T - the type of items observed and emitted by the Subject

Parameters:

maxSize - the maximum number of buffered items

Returns:

the created subject

createWithTime

@CheckReturnValue
public static <T> ReplayProcessor<T> createWithTime(long maxAge,
                                                     java.util.concurrent.TimeUnit unit,
                                                     Scheduler scheduler)

Creates a time-bounded ReplayProcessor.

In this setting, the ReplayProcessor internally tags each observed item with a timestamp value supplied by the Scheduler and keeps only those whose age is less than the supplied time value converted to milliseconds. For example, an item arrives at T=0 and the max age is set to 5; at T>=5 this first item is then evicted by any subsequent item or termination event, leaving the buffer empty.

Once the subject is terminated, observers subscribing to it will receive items that remained in the buffer after the terminal event, regardless of their age.

If an observer subscribes while the ReplayProcessor is active, it will observe only those items from within the buffer that have an age less than the specified time, and each item observed thereafter, even if the buffer evicts items due to the time constraint in the mean time. In other words, once an observer subscribes, it observes items without gaps in the sequence except for any outdated items at the beginning of the sequence.

Note that terminal notifications (onError and onComplete) trigger eviction as well. For example, with a max age of 5, the first item is observed at T=0, then an onComplete notification arrives at T=10. If an observer subscribes at T=11, it will find an empty ReplayProcessor with just an onComplete notification.

Type Parameters:

T - the type of items observed and emitted by the Subject

Parameters:

maxAge - the maximum age of the contained items

unit - the time unit of time

scheduler - the Scheduler that provides the current time

Returns:

the created subject

createWithTimeAndSize

@CheckReturnValue
public static <T> ReplayProcessor<T> createWithTimeAndSize(long maxAge,
                                                            java.util.concurrent.TimeUnit unit,
                                                            Scheduler scheduler,
                                                            int maxSize)

Creates a time- and size-bounded ReplayProcessor.

In this setting, the ReplayProcessor internally tags each received item with a timestamp value supplied by the Scheduler and holds at most size items in its internal buffer. It evicts items from the start of the buffer if their age becomes less-than or equal to the supplied age in milliseconds or the buffer reaches its size limit.

When observers subscribe to a terminated ReplayProcessor, they observe the items that remained in the buffer after the terminal notification, regardless of their age, but at most size items.

If an observer subscribes while the ReplayProcessor is active, it will observe only those items from within the buffer that have age less than the specified time and each subsequent item, even if the buffer evicts items due to the time constraint in the mean time. In other words, once an observer subscribes, it observes items without gaps in the sequence except for the outdated items at the beginning of the sequence.

Note that terminal notifications (onError and onComplete) trigger eviction as well. For example, with a max age of 5, the first item is observed at T=0, then an onComplete notification arrives at T=10. If an observer subscribes at T=11, it will find an empty ReplayProcessor with just an onComplete notification.

Type Parameters:

T - the type of items observed and emitted by the Subject

Parameters:

maxAge - the maximum age of the contained items

unit - the time unit of time

maxSize - the maximum number of buffered items

scheduler - the Scheduler that provides the current time

Returns:

the created subject

subscribeActual

protected void subscribeActual(org.reactivestreams.Subscriber<? super T> s)

Description copied from class: Flowable

Operator implementations (both source and intermediate) should implement this method that performs the necessary business logic.

There is no need to call any of the plugin hooks on the current Flowable instance or the Subscriber.

Specified by:

subscribeActual in class Flowable<T>

Parameters:

s - the incoming Subscriber, never null

onSubscribe

public void onSubscribe(org.reactivestreams.Subscription s)

onNext

public void onNext(T t)

onError

public void onError(java.lang.Throwable t)

onComplete

public void onComplete()

hasSubscribers

public boolean hasSubscribers()

Description copied from class: FlowableProcessor

Returns true if the subject has subscribers.

The method is thread-safe.

Specified by:

hasSubscribers in class FlowableProcessor<T>

Returns:

true if the subject has subscribers

getThrowable

public java.lang.Throwable getThrowable()

Description copied from class: FlowableProcessor

Returns the error that caused the Subject to terminate or null if the Subject hasn't terminated yet.

The method is thread-safe.

Specified by:

getThrowable in class FlowableProcessor<T>

Returns:

the error that caused the Subject to terminate or null if the Subject hasn't terminated yet

getValue

public T getValue()

Returns a single value the Subject currently has or null if no such value exists.

The method is thread-safe.

Returns:

a single value the Subject currently has or null if no such value exists

getValues

public java.lang.Object[] getValues()

Returns an Object array containing snapshot all values of the Subject.

The method is thread-safe.

Returns:

the array containing the snapshot of all values of the Subject

getValues

public T[] getValues(T[] array)

Returns a typed array containing a snapshot of all values of the Subject.

The method follows the conventions of Collection.toArray by setting the array element after the last value to null (if the capacity permits).

The method is thread-safe.

Parameters:

array - the target array to copy values into if it fits

Returns:

the given array if the values fit into it or a new array containing all values

hasComplete

public boolean hasComplete()

Description copied from class: FlowableProcessor

Returns true if the subject has reached a terminal state through a complete event.

The method is thread-safe.

Specified by:

hasComplete in class FlowableProcessor<T>

Returns:

true if the subject has reached a terminal state through a complete event

See Also:

FlowableProcessor.hasThrowable()

hasThrowable

public boolean hasThrowable()

Description copied from class: FlowableProcessor

Returns true if the subject has reached a terminal state through an error event.

The method is thread-safe.

Specified by:

hasThrowable in class FlowableProcessor<T>

Returns:

true if the subject has reached a terminal state through an error event

See Also:

FlowableProcessor.getThrowable(), FlowableProcessor.hasComplete()

hasValue

public boolean hasValue()

Returns true if the subject has any value.

The method is thread-safe.

Returns:

true if the subject has any value