Module io.smallrye.mutiny
Package io.smallrye.mutiny.operators

Class AbstractUni<T>

java.lang.Object
io.smallrye.mutiny.operators.AbstractUni<T>
All Implemented Interfaces:
Uni<T>
Direct Known Subclasses:
UniOperator
public abstract class AbstractUni<T> extends Object implements Uni<T>

  • Constructor Details

    • AbstractUni

      public AbstractUni()

  • Method Details

    • subscribe

      public abstract void subscribe(UniSubscriber<? super T> subscriber)

    • subscribe

      public static <T> void subscribe(Uni<? extends T> upstream, UniSubscriber<? super T> subscriber)
      Encapsulates subscription to slightly optimize the AbstractUni case.

      In the case of AbstractUni, it avoid creating the UniSubscribe group instance.

      Type Parameters:
      T - the type of item
      Parameters:
      upstream - the upstream, must not be null (not checked)
      subscriber - the subscriber, must not be null (not checked)

    • subscribe

      public UniSubscribe<T> subscribe()
      Description copied from interface: Uni
      Requests the Uni to start resolving the item and allows configuring how the signals are propagated (using a UniSubscriber, callbacks, or a CompletionStage. Unlike Uni.await(), this method configures non-blocking retrieval of the item and failure.

      Examples: 

       
     Uni<String> uni = ...;

    Subscription sub = uni.subscribe().with( // The return subscription can be used to cancel the operation
              item -> {},           // Callback calls on item
              failure -> {}           // Callback calls on failure
    );

    UniSubscriber<String> myUniSubscriber = ...
    uni.subscribe().withSubscriber(myUniSubscriber); // Subscribes to the Uni with the passed subscriber

    CompletableFuture future = uni.subscribe().asCompletableFuture(); // Get a CompletionStage receiving the item or failure
    // Cancelling the returned future cancels the subscription.
      Specified by:
      subscribe in interface Uni<T>
      Returns:
      the object to configure the subscription.
      See Also:

    • onItem

      public UniOnItem<T> onItem()
      Description copied from interface: Uni
      Configures the action to execute when the observed Uni emits the item (potentially null).

      Examples: 

       
 Uni<T> uni = ...;
 uni.onItem().transform(x -> ...); // Transform the item into another item (~ map)
 uni.onItem().transformToUni(x -> ...); // Transform the item into a Uni (~ flatMap)
      Specified by:
      onItem in interface Uni<T>
      Returns:
      the object to configure the action to execute when an item is emitted

    • ifNoItem

      public UniIfNoItem<T> ifNoItem()
      Description copied from interface: Uni
      Produces a Uni reacting when a no item event is fired by the upstream uni during the specified time period.

      This Uni detects if this Uni does not emit an item before the configured timeout.

      Examples: 

      
 uni.ifNoItem().after(Duration.ofMillis(1000)).fail() // Propagate a TimeOutException
 uni.ifNoItem().after(Duration.ofMillis(1000)).recoverWithValue("fallback") // Inject a fallback item on timeout
 uni.ifNoItem().after(Duration.ofMillis(1000)).on(myExecutor)... // Configure the executor calling on timeout actions
 uni.ifNoItem().after(Duration.ofMillis(1000)).fail().onFailure().retry().atMost(5) // Retry five times
      Specified by:
      ifNoItem in interface Uni<T>
      Returns:
      the on timeout group

    • onFailure

      public UniOnFailure<T> onFailure()
      Description copied from interface: Uni
      Like Uni.onFailure(Predicate) but applied to all failures fired by the upstream uni. It allows configuring the on failure behavior (recovery, retry...).
      Specified by:
      onFailure in interface Uni<T>
      Returns:
      a UniOnFailure on which you can specify the on failure action

    • onFailure

      public UniOnFailure<T> onFailure(Predicate<? super Throwable> predicate)
      Description copied from interface: Uni
      Configures a predicate filtering the failures on which the behavior (specified with the returned UniOnFailure) is applied.

      For instance, to only when an IOException is fired as failure you can use: uni.onFailure(IOException.class).recoverWithItem("hello")

      The fallback value (hello) will only be used if the upstream uni fire a failure of type IOException.

      Specified by:
      onFailure in interface Uni<T>
      Parameters:
      predicate - the predicate, null means applied to all failures
      Returns:
      a UniOnFailure configured with the given predicate on which you can specify the on failure action

    • onFailure

      public UniOnFailure<T> onFailure(Class<? extends Throwable> typeOfFailure)
      Description copied from interface: Uni
      Configures a type of failure filtering the failures on which the behavior (specified with the returned UniOnFailure) is applied.

      For instance, to only when an IOException is fired as failure you can use: uni.onFailure(IOException.class).recoverWithItem("hello")

      The fallback value (hello) will only be used if the upstream uni fire a failure of type IOException.

      Specified by:
      onFailure in interface Uni<T>
      Parameters:
      typeOfFailure - the class of exception, must not be null
      Returns:
      a UniOnFailure configured with the given predicate on which you can specify the on failure action

    • onSubscription

      public UniOnSubscribe<T> onSubscription()
      Description copied from interface: Uni
      Configures the action to execute when the observed Uni sends a UniSubscription. The downstream does not have a subscription yet. It will be passed once the configured action completes.

      Example: 

       
 uni.onSubscription().invoke(sub -> System.out.println("subscribed"));
 // Delay the subscription by 1 second (or until an asynchronous action completes)
 uni.onSubscription().call(sub -> Uni.createFrom(1).onItem().delayIt().by(Duration.ofSecond(1)));
      Specified by:
      onSubscription in interface Uni<T>
      Returns:
      the object to configure the action to execution on subscription.

    • onItemOrFailure

      public UniOnItemOrFailure<T> onItemOrFailure()
      Description copied from interface: Uni
      Configures the action to execute when the observed Uni emits either an item (potentially null)) or a failure. Unlike Uni.onItem() and Uni.onFailure() the action would handle both cases in on "go".
      Specified by:
      onItemOrFailure in interface Uni<T>
      Returns:
      the object to configure the action to execute when an item is emitted or when a failure is propagated.

    • await

      public UniAwait<T> await()
      Description copied from interface: Uni
      Awaits (blocking the caller thread) until the item or a failure is emitted by the observed Uni. If the observed uni fails, the failure is thrown. In the case of a checked exception, the exception is wrapped into a CompletionException.

      Examples: 

       
 Uni<T> uni = ...;
 T res = uni.await().indefinitely(); // Await indefinitely until it get the item.
 T res = uni.await().atMost(Duration.ofMillis(1000)); // Awaits at most 1s. After that, a TimeoutException is thrown
 Optional<T> res = uni.await().asOptional().indefinitely(); // Retrieves the item as an Optional, empty if the item is null
      Specified by:
      await in interface Uni<T>
      Returns:
      the object to configure the retrieval.

    • awaitUsing

      public UniAwait<T> awaitUsing(Context context)
      Description copied from interface: Uni
      Awaits (blocking the caller thread) until the item or a failure is emitted by the observed Uni. If the observed uni fails, the failure is thrown. In the case of a checked exception, the exception is wrapped into a CompletionException.

      Examples: 

       
 Uni<T> uni = ...;
 T res = uni.awaitUsing(context).indefinitely(); // Await indefinitely until it get the item.
 T res = uni.awaitUsing(context).atMost(Duration.ofMillis(1000)); // Awaits at most 1s. After that, a TimeoutException is thrown
 Optional<T> res = uni.awaitUsing(context).asOptional().indefinitely(); // Retrieves the item as an Optional, empty if the item is null
      Specified by:
      awaitUsing in interface Uni<T>
      Parameters:
      context - the context, cannot be null
      Returns:
      the object to configure the retrieval.

    • emitOn

      public Uni<T> emitOn(Executor executor)
      Description copied from interface: Uni
      Produces a new Uni invoking the UniSubscriber.onItem(Object) and UniSubscriber.onFailure(Throwable) on the supplied Executor.

      Instead of receiving the item event on the thread firing the event, this method influences the threading context to switch to a thread from the given executor.

      Be careful as this operator can lead to concurrency problems with non thread-safe objects such as CDI request-scoped beans.

      Specified by:
      emitOn in interface Uni<T>
      Parameters:
      executor - the executor to use, must not be null
      Returns:
      a new Uni

    • runSubscriptionOn

      public Uni<T> runSubscriptionOn(Executor executor)
      Description copied from interface: Uni
      When a subscriber subscribes to this Uni, executes the subscription to the upstream Uni on a thread from the given executor. As a result, the UniSubscriber.onSubscribe(UniSubscription) method will be called on this thread (except mentioned otherwise)
      Specified by:
      runSubscriptionOn in interface Uni<T>
      Parameters:
      executor - the executor to use, must not be null
      Returns:
      a new Uni

    • memoize

      public UniMemoize<T> memoize()
      Description copied from interface: Uni
      Configure memoization of the Uni item or failure.
      Specified by:
      memoize in interface Uni<T>
      Returns:
      the object to configure memoization

    • cache

      public Uni<T> cache()

    • convert

      public UniConvert<T> convert()
      Description copied from interface: Uni
      Converts an Uni to other types such as CompletionStage

      Examples: 

       
 uni.convert().toCompletionStage(); // Convert to CompletionStage using convenience method
 uni.convert().with(BuiltinConverters.toCompletionStage()); // Convert to CompletionStage using BuiltInConverters
 uni.convert().with(uni -> x); // Convert with a custom lambda converter
      Specified by:
      convert in interface Uni<T>
      Returns:
      the object to convert an Uni instance
      See Also:

    • toMulti

      public Multi<T> toMulti()
      Description copied from interface: Uni
      Creates an instance of Multi from this Uni.

      When a subscriber subscribes to the returned Multi and request an item, it subscribes to this Uni and the events from this Uni are propagated to the Multi:

      • if this Uni emits a non-null item - this item is propagated to the Multi and followed with the completion event
      • if this Uni emits a null item - the Multi fires the completion event
      • if this Uni emits a failure, this failure event is propagated by the Multi

      It's important to note that the subscription to this Uni happens when the subscriber to the produced Multi requests items, and not at subscription time.

      Specified by:
      toMulti in interface Uni<T>
      Returns:
      the produced Multi, never null

    • repeat

      public UniRepeat<T> repeat()
      Description copied from interface: Uni
      Allows configuring repeating behavior. Repeating allow transforming a Uni into a Multi either a specific amount of times or indefinitely. Each time, a new subscription is attempted on the Uni. Cancelling the subscription stops the repeating behavior.
      Specified by:
      repeat in interface Uni<T>
      Returns:
      the object to configure the repeating behavior.

    • onTermination

      public UniOnTerminate<T> onTermination()
      Description copied from interface: Uni
      Configures actions to be performed on termination, that is, on item, on failure, or when the subscriber cancels the subscription.
      Specified by:
      onTermination in interface Uni<T>
      Returns:
      the object to configure the termination actions.

    • onCancellation

      public UniOnCancel<T> onCancellation()
      Description copied from interface: Uni
      Configures actions to be performed when the subscriber cancels the subscription.
      Specified by:
      onCancellation in interface Uni<T>
      Returns:
      the object to configure the cancellation actions.

    • log

      public Uni<T> log(String identifier)
      Description copied from interface: Uni
      Log events (onSubscribe, onItem, ...) as they come from the upstream or the subscriber.

      Events will be logged as long as the Uni hasn't been cancelled or terminated. Logging is framework-agnostic and can be configured in the Infrastructure class.

      Specified by:
      log in interface Uni<T>
      Parameters:
      identifier - an identifier of this operator to be used in log events
      Returns:
      a new Uni
      See Also:

    • log

      public Uni<T> log()
      Description copied from interface: Uni
      Log events (onSubscribe, onItem, ...) as they come from the upstream or the subscriber, and derives the identifier from the upstream operator class "simple name".

      Events will be logged as long as the Uni hasn't been cancelled or terminated. Logging is framework-agnostic and can be configured in the Infrastructure class.

      Specified by:
      log in interface Uni<T>
      Returns:
      a new Uni
      See Also:

    • withContext

      public <R> Uni<R> withContext(BiFunction<Uni<T>,Context,Uni<R>> builder)
      Description copied from interface: Uni
      Materialize the subscriber Context for a sub-pipeline.

      The provided function takes this Uni and the Context as parameters, and returns a Uni to build the sub-pipeline, as in: 

       
 someUni.withContext((uni, ctx) -> uni.onItem().transform(n -> n + "::" + ctx.getOrElse("foo", () -> "yolo")));

      Note that the builder function is called at subscription time, so it cannot see context updates from upstream operators yet.

      Specified by:
      withContext in interface Uni<T>
      Type Parameters:
      R - the resulting Uni type
      Parameters:
      builder - the function that builds the sub-pipeline from this Uni and the Context, must not be null, must not return null.
      Returns:
      the resulting Uni