reactive-streams-commons

A joint research effort for building highly optimized Reactive-Streams compliant operators. Current implementors include RxJava2 and Reactor.

Java 8 required.

Maven

repositories {
    maven { url 'https://repo.spring.io/libs-snapshot' }
}

dependencies {
    compile 'io.projectreactor:reactive-streams-commons:0.6.0.BUILD-SNAPSHOT'
}

Snapshot directory.

Operator-fusion documentation

• Operator fusion, 1/2
• Operator fusion, 2/2
• Fusion Matrix

Supported datasources

I.e., converts non-reactive data sources into Publishers.

• PublisherAmb : relays signals of that source Publisher which responds first with any signal
• PublisherArray : emits the elements of an array
• PublisherCallable : emits a single value returned by a Callable
• PublisherCompletableFuture : emits a single value produced by a CompletableFuture
• PublisherConcatArray : concatenate an array of Publishers
• PublisherConcatIterable : concatenate an Iterable sequence of Publishers
• PublisherDefer : calls a Supplier to create the actual Publisher the Subscriber will be subscribed to.
• PublisherEmpty : does not emit any value and calls onCompleted; use instance() to get its singleton instance with the proper type parameter
• PublisherError : emits a constant or generated Throwable exception
• PublisherFuture : awaits and emits a single value emitted by a Future
• PublisherGenerate : generate signals one-by-one via a function
• PublisherInterval : periodically emits an ever increasing sequence of long values
• PublisherIterable : emits the elements of an Iterable
• PublisherJust : emits a single value
• PublisherNever : doesn't emit any signal other than onSubscribe; use instance() to get its singleton instance with the proper type parameter
• PublisherRange : emits a range of integer values
• PublisherStream : emits elements of a Stream
• PublisherTimer : emit a single 0L after a specified amount of time
• PublisherUsing : create a resource, stream values in a Publisher derived from the resource and release the resource when the sequence completes or the Subscriber cancels
• PublisherZip : Repeatedly takes one item from all source Publishers and runs it through a function to produce the output item

Supported transformations

• ConnectablePublisherAutoConnect given a ConnectablePublisher, it connects to it once the given amount of subscribers subscribed
• ConnectablePublisherRefCount given a ConnectablePublisher, it connects to it once the given amount of subscribers subscribed to it and disconnects once all subscribers cancelled
• ConnectablePublisherPublish : allows dispatching events from a single source to multiple subscribers similar to a Processor but the connection can be manually established or stopped.
• PublisherAccumulate : Accumulates the source values with an accumulator function and returns the intermediate results of this function application
• PublisherAggregate : Aggregates the source values with an aggergator function and emits the last result.
• PublisherAll : emits a single true if all values of the source sequence match the predicate
• PublisherAny : emits a single true if any value of the source sequence matches the predicate
• PublisherAwaitOnSubscribe : makes sure onSubscribe can't trigger the onNext events until it returns
• PublisherBuffer : buffers certain number of subsequent elements and emits the buffers
• PublisherBufferBoundary : buffers elements into continuous, non-overlapping lists where another Publisher signals the start/end of the buffer regions
• PublisherBufferBoundaryAndSize : buffers elements into continuous, non-overlapping lists where the each buffer is emitted when they become full or another Publisher signals the boundary of the buffer regions
• PublisherBufferStartEnd : buffers elements into possibly overlapping buffers whose boundaries are determined by a start Publisher's element and a signal of a derived Publisher
• PublisherCollect : collects the values into a container and emits it when the source completes
• PublisherCombineLatest : combines the latest values of many sources through a function
• PublisherConcatMap : Maps each upstream value into a Publisher and concatenates them into one sequence of items
• PublisherCount : counts the number of elements the source sequence emits
• PublisherDistinct : filters out elements that have been seen previously according to a custom collection
• PublisherDistinctUntilChanged : filters out subsequent and repeated elements
• PublisherDefaultIfEmpty : emits a single value if the source is empty
• PublisherDelaySubscription : delays the subscription to the main source until the other source signals a value or completes
• PublisherDetach : detaches the both the child Subscriber and the Subscription on termination or cancellation.
• PublisherDrop : runs the source in unbounded mode and drops values if the downstream doesn't request fast enough
• PublisherElementAt : emits the element at the specified index location
• PublisherFilter : filters out values which doesn't pass a predicate
• PublisherFlatMap : maps a sequence of values each into a Publisher and flattens them back into a single sequence, interleaving events from the various inner Publishers
• PublisherFlattenIterable : concatenates values from Iterable sequences generated via a mapper function
• PublisherGroupBy : groups source elements into their own Publisher sequences via a key function
• PublisherIgnoreElements : ignores values and passes only the terminal signals along
• PublisherIsEmpty : returns a single true if the source sequence is empty
• PublisherLatest : runs the source in unbounded mode and emits the latest value if the downstream doesn't request fast enough
• PublisherLift : maps the downstream Subscriber into an upstream Subscriber which allows implementing custom operators via lambdas
• PublisherMap : map values to other values via a function
• PublisherPeek : peek into the lifecycle and signals of a stream
• PublisherReduce : aggregates the source values with the help of an accumulator function and emits the the final accumulated value
• PublisherRepeat : repeatedly streams the source sequence fixed or unlimited times
• PublisherRepeatPredicate : repeatedly stream the source if a predicate returns true
• PublisherRepeatWhen : repeats a source when a companion sequence signals an item in response to the main's completion signal
• PublisherResume : if the source fails, the stream is resumed by another Publisher returned by a function for the failure exception
• PublisherRetry : retry a failed source sequence fixed or unlimited times
• PublisherRetryPredicate : retry if a predicate function returns true for the exception
• PublisherRetryWhen : retries a source when a companion sequence signals an item in response to the main's error signal
• PublisherSample : samples the main source whenever the other Publisher signals a value
• PublisherScan : aggregates the source values with the help of an accumulator function and emits the intermediate results
• PublisherSingle : expects the source to emit only a single item
• PublisherSkip : skips a specified amount of values
• PublisherSkipLast : skips the last N elements
• PublisherSkipUntil : skips values until another sequence signals a value or completes
• PublisherSkipWhile: skips values while the predicate returns true
• PublisherStreamCollector : Collects the values from the source sequence into a java.util.stream.Collector instance; see Collectors utility class in Java 8+
• PublisherSwitchIfEmpty : continues with another sequence if the first sequence turns out to be empty.
• PublisherSwitchMap : switches to and streams a Publisher generated via a function whenever the upstream signals a value
• PublisherTake : takes a specified amount of values and completes
• PublisherTakeLast : emits only the last N values the source emitted before its completion
• PublisherTakeWhile : relays values while a predicate returns true for the values (checked before each value)
• PublisherTakeUntil : relays values until another Publisher signals
• PublisherTakeUntilPredicate : relays values until a predicate returns true (checked after each value)
• PublisherThrottleFirst : takes a value from upstream then uses the duration provided by a generated Publisher to skip other values until that other Publisher signals
• PublisherThrottleTimeout : emits the last value from upstream only if there were no newer values emitted during the time window provided by a publisher for that particular last value
• PublisherTimeout uses per-item Publishers that when they fire mean the timeout for that particular item unless a new item arrives in the meantime
• PublisherWindow : splits the source sequence into possibly overlapping windows of given size
• PublisherWindowBatch : batches the source sequence into continuous, non-overlapping windows where the length of the windows is determined by a fresh boundary Publisher or a maximum elemenets in that window
• PublisherWindowBoundary : splits the source sequence into continuous, non-overlapping windows where the window boundary is signalled by another Publisher
• PublisherWindowBoundaryAndSize : splits the source sequence into continuous, non-overlapping windows where the window boundary is signalled by another Publisher or if a window received a specified amount of values
• PublisherWindowStartEnd : splits the source sequence into potentially overlapping windows controlled by a start Publisher and a derived end Publisher for each start value
• PublisherWithLatestFrom : combines values from a master source with the latest values of another Publisher via a function
• PublisherZip : Repeatedly takes one item from all source Publishers and runs it through a function to produce the output item
• PublisherZipIterable : pairwise combines a sequence of values with elements from an iterable

Supported extractions

I.e., these allow leaving the reactive-streams world.

• BlockingIterable : an iterable that consumes a Publisher in a blocking fashion
• BlockingFuture : can return a future that consumes the source entierly and returns the very last value
• BlockingStream : allows creating sequential and parallel j.u.stream.Stream flows out of a source Publisher
• PublisherBase.blockingFirst : returns the very first value of the source, blocking if necessary; returns null for an empty sequence.
• PublisherBase.blockingLast : returns the very last value of the source, blocking if necessary; returns null for an empty sequence.
• PublisherBase.peekLast : returns the last value of a synchronous source or likely null for other or empty sequences.