com.jakewharton.rxrelay2

Class ReplayRelay<T>

java.lang.Object

io.reactivex.Observable<T>

com.jakewharton.rxrelay2.Relay<T>

com.jakewharton.rxrelay2.ReplayRelay<T>

Type Parameters:

T - the value type

All Implemented Interfaces:

io.reactivex.functions.Consumer<T>, io.reactivex.ObservableSource<T>

public final class ReplayRelay<T>
extends Relay<T>

Replays events to Observers.

Example usage:

 

  ReplayRelay<Object> relay = new ReplayRelay<>();
  relay.accept("one");
  relay.accept("two");
  relay.accept("three");

  // both of the following will get the values from above
  relay.subscribe(observer1);
  relay.subscribe(observer2);

   

Method Summary

Modifier and Type	Method and Description
void	accept(T value)
static <T> ReplayRelay<T>	create() Creates an unbounded replay relay.
static <T> ReplayRelay<T>	create(int capacityHint) Creates an unbounded replay relay with the specified initial buffer capacity.
static <T> ReplayRelay<T>	createWithSize(int maxSize) Creates a size-bounded replay relay.
static <T> ReplayRelay<T>	createWithTime(long maxAge, TimeUnit unit, io.reactivex.Scheduler scheduler) Creates a time-bounded replay relay.
static <T> ReplayRelay<T>	createWithTimeAndSize(long maxAge, TimeUnit unit, io.reactivex.Scheduler scheduler, int maxSize) Creates a time- and size-bounded replay subject.
T	getValue() Returns a single value the Relay currently has or null if no such value exists.
Object[]	getValues() Returns an Object array containing snapshot all values of the Relay.
T[]	getValues(T[] array) Returns a typed array containing a snapshot of all values of the Relay.
boolean	hasObservers() Returns true if the subject has any Observers.
boolean	hasValue() Returns true if the relay has any value.
protected void	subscribeActual(io.reactivex.Observer<? super T> observer)

Methods inherited from class com.jakewharton.rxrelay2.Relay

toSerialized

Methods inherited from class io.reactivex.Observable

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, 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, doOnComplete, doOnDispose, doOnEach, doOnEach, doOnError, doOnLifecycle, doOnNext, 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, 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, onErrorResumeNext, onErrorResumeNext, onErrorReturn, onErrorReturnItem, onExceptionResumeNext, onTerminateDetach, publish, publish, range, rangeLong, 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, 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, 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, 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, toFlowable, toFuture, toList, toList, toList, toMap, toMap, toMap, toMultimap, toMultimap, toMultimap, toMultimap, 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, wrap, 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

Method Detail

create

public static <T> ReplayRelay<T> create()

Creates an unbounded replay relay.

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.

create

public static <T> ReplayRelay<T> create(int capacityHint)

Creates an unbounded replay relay 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 ReplayRelay 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.

Parameters:

capacityHint - the initial buffer capacity

createWithSize

public static <T> ReplayRelay<T> createWithSize(int maxSize)

Creates a size-bounded replay relay.

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

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

If an observer subscribes while the ReplayRelay 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.

Parameters:

maxSize - the maximum number of buffered items

createWithTime

public static <T> ReplayRelay<T> createWithTime(long maxAge,
                                                TimeUnit unit,
                                                io.reactivex.Scheduler scheduler)

Creates a time-bounded replay relay.

In this setting, the ReplayRelay 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 ReplayRelay 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 ReplayRelay with just an onComplete notification.

Parameters:

maxAge - the maximum age of the contained items

unit - the time unit of time

scheduler - the Scheduler that provides the current time

createWithTimeAndSize

public static <T> ReplayRelay<T> createWithTimeAndSize(long maxAge,
                                                       TimeUnit unit,
                                                       io.reactivex.Scheduler scheduler,
                                                       int maxSize)

Creates a time- and size-bounded replay subject.

In this setting, the ReplayRelay 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 ReplayRelay, 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 ReplayRelay 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 ReplayRelay with just an onComplete notification.

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

subscribeActual

protected void subscribeActual(io.reactivex.Observer<? super T> observer)

Specified by:

subscribeActual in class io.reactivex.Observable<T>

accept

public void accept(T value)

Description copied from class: Relay

Specified by:

accept in interface io.reactivex.functions.Consumer<T>

Specified by:

accept in class Relay<T>

hasObservers

public boolean hasObservers()

Description copied from class: Relay

Returns true if the subject has any Observers.

The method is thread-safe.

Specified by:

hasObservers in class Relay<T>

getValue

public T getValue()

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

The method is thread-safe.

getValues

public Object[] getValues()

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

The method is thread-safe.

getValues

public T[] getValues(T[] array)

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

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

hasValue

public boolean hasValue()

Returns true if the relay has any value.

The method is thread-safe.