Package reactor.core.publisher

Interface Sinks.One<T>

All Superinterfaces:

Scannable, Sinks.Empty<T>

All Known Implementing Classes:

SinkOneSerialized

Enclosing class:

Sinks

public static interface Sinks.One<T>
extends Sinks.Empty<T>

A base interface for standalone Sinks with Mono semantics.

The sink can be exposed to consuming code as a Mono via its Sinks.Empty.asMono() view.

Author:

Simon Baslé, Stephane Maldini

Nested Class Summary

Nested classes/interfaces inherited from interface reactor.core.Scannable

Scannable.Attr<T>

Field Summary

Fields inherited from interface reactor.core.Scannable

OPERATOR_NAME_UNRELATED_WORDS_PATTERN

Method Summary

Modifier and Type	Method	Description
void	emitValue(@Nullable T value, Sinks.EmitFailureHandler failureHandler)	A simplified attempt at emitting a non-null element via the tryEmitValue(Object) API, generating an onNext signal immediately followed by an Subscriber.onComplete() signal.
Sinks.EmitResult	tryEmitValue(@Nullable T value)	Try to complete the Mono with an element, generating an onNext signal immediately followed by an onComplete signal.

Methods inherited from interface reactor.core.Scannable

actuals, inners, isScanAvailable, name, parents, scan, scanOrDefault, scanUnsafe, stepName, steps, tags, tagsDeduplicated

Methods inherited from interface reactor.core.publisher.Sinks.Empty

asMono, currentSubscriberCount, emitEmpty, emitError, tryEmitEmpty, tryEmitError

Method Details

tryEmitValue

Sinks.EmitResult tryEmitValue(@Nullable T value)

Try to complete the Mono with an element, generating an onNext signal immediately followed by an onComplete signal. A null value will only trigger the onComplete. The result of the attempt is represented as an Sinks.EmitResult, which possibly indicates error cases.

See the list of failure Sinks.EmitResult in emitValue(Object, EmitFailureHandler) javadoc for an example of how each of these can be dealt with, to decide if the emit API would be a good enough fit instead.

Might throw an unchecked exception as a last resort (eg. in case of a fatal error downstream which cannot be propagated to any asynchronous handler, a bubbling exception, ...).

Parameters:

value - the value to emit and complete with, or null to only trigger an onComplete

Returns:

an Sinks.EmitResult, which should be checked to distinguish different possible failures

See Also:

• emitValue(Object, Sinks.EmitFailureHandler)
• Subscriber.onNext(Object)
• Subscriber.onComplete()

emitValue

void emitValue(@Nullable T value,
 Sinks.EmitFailureHandler failureHandler)

A simplified attempt at emitting a non-null element via the tryEmitValue(Object) API, generating an onNext signal immediately followed by an Subscriber.onComplete() signal. If the result of the attempt is not a success, implementations SHOULD retry the tryEmitValue(Object) call IF the provided Sinks.EmitFailureHandler returns true. Otherwise, failures are dealt with in a predefined way that might depend on the actual sink implementation (see below for the vanilla reactor-core behavior).

Generally, tryEmitValue(Object) is preferable since it allows a custom handling of error cases, although this implies checking the returned Sinks.EmitResult and correctly acting on it. This API is intended as a good default for convenience.

When the Sinks.EmitResult is not a success, vanilla reactor-core operators have the following behavior:

• Sinks.EmitResult.FAIL_ZERO_SUBSCRIBER: no particular handling. should ideally discard the value but at that point there's no Subscriber from which to get a contextual discard handler.
• Sinks.EmitResult.FAIL_OVERFLOW: discard the value (Operators.onDiscard(Object, Context)) then call Sinks.Empty.emitError(Throwable, Sinks.EmitFailureHandler) with a Exceptions.failWithOverflow(String) exception.
• Sinks.EmitResult.FAIL_CANCELLED: discard the value (Operators.onDiscard(Object, Context)).
• Sinks.EmitResult.FAIL_TERMINATED: drop the value (Operators.onNextDropped(Object, Context)).
• Sinks.EmitResult.FAIL_NON_SERIALIZED: throw an Sinks.EmissionException mentioning RS spec rule 1.3. Note that Sinks.unsafe() never trigger this result. It would be possible for an Sinks.EmitFailureHandler to busy-loop and optimistically wait for the contention to disappear to avoid this case for safe sinks...

Might throw an unchecked exception as a last resort (eg. in case of a fatal error downstream which cannot be propagated to any asynchronous handler, a bubbling exception, a Sinks.EmitResult.FAIL_NON_SERIALIZED as described above, ...).

Parameters:

value - the value to emit and complete with, a null is actually acceptable to only trigger an onComplete

failureHandler - the failure handler that allows retrying failed Sinks.EmitResult.

Throws:

Sinks.EmissionException - on non-serialized access

See Also:

• tryEmitValue(Object)
• Subscriber.onNext(Object)
• Subscriber.onComplete()