Package io.micronaut.core.execution

Interface ExecutionFlow<T>

Type Parameters:

T - The flow type

All Known Subinterfaces:

CompletableFutureExecutionFlow<T>, DelayedExecutionFlow<T>, ImperativeExecutionFlow<T>, ReactiveExecutionFlow<T>

@Internal
public interface ExecutionFlow<T>

The execution flow class represents a data flow which state can be represented as a simple imperative flow or an async/reactive. The state can be resolved or lazy - based on the implementation. NOTE: The instance of the flow is not supposed to be used after a mapping operator is used.

Since:

4.0.0

Author:

Denis Stepanov

Method Summary

Modifier and Type	Method	Description
static <T> @NonNull ExecutionFlow<T>	async(@NonNull Executor executor, @NonNull Supplier<? extends ExecutionFlow<T>> supplier)	Create a flow by invoking a supplier asynchronously.
default void	cancel()	Send an optional hint to the upstream producer that the result of this flow is no longer needed and can be discarded.
void	completeTo(@NonNull CompletableFuture<T> completableFuture)	Completes the flow to the completable future.
static <T> @NonNull ExecutionFlow<T>	empty()	Create a simple flow representing an empty state.
static <K> @NonNull ExecutionFlow<K>	error(@NonNull Throwable e)	Create a simple flow representing an error.
<R> @NonNull ExecutionFlow<R>	flatMap(@NonNull Function<? super T,? extends ExecutionFlow<? extends R>> transformer)	Map a not-empty value to a new flow.
static <K> @NonNull ExecutionFlow<K>	just(K value)	Create a simple flow representing a value.
<R> @NonNull ExecutionFlow<R>	map(@NonNull Function<? super T,? extends R> transformer)	Map a not-empty value.
void	onComplete(@NonNull BiConsumer<? super T,Throwable> fn)	Invokes a provided function when the flow is resolved, or immediately if it is already done.
@NonNull ExecutionFlow<T>	onErrorResume(@NonNull Function<? super Throwable,? extends ExecutionFlow<? extends T>> fallback)	Supply a new flow if the existing flow is erroneous.
@NonNull ExecutionFlow<T>	putInContext(@NonNull String key, @NonNull Object value)	Store a contextual value.
default @NonNull ExecutionFlow<T>	putInContextIfAbsent(@NonNull String key, @NonNull Object value)	Store a contextual value if it is absent.
<R> @NonNull ExecutionFlow<R>	then(@NonNull Supplier<? extends ExecutionFlow<? extends R>> supplier)	Supply a new flow after the existing flow value is resolved.
default @NonNull ExecutionFlow<T>	timeout(@NonNull Duration timeout, @NonNull ScheduledExecutorService scheduler, @Nullable BiConsumer<T,Throwable> onDiscard)	Create a new ExecutionFlow that either returns the same result or, if the timeout expires before the result is received, a TimeoutException.
default @NonNull CompletableFuture<T>	toCompletableFuture()	Converts the existing flow into the completable future.
@Nullable ImperativeExecutionFlow<T>	tryComplete()	Create an ImperativeExecutionFlow from this execution flow, if possible.
default @Nullable Throwable	tryCompleteError()	Alternative to tryComplete() which will unwrap the flow's error.
default T	tryCompleteValue()	Alternative to tryComplete() which will unwrap the flow's value.

Method Details

just

@NonNull
static <K> @NonNull ExecutionFlow<K> just(@Nullable
 K value)

Create a simple flow representing a value.

Type Parameters:

K - The value type

Parameters:

value - The value

Returns:

a new flow

error

@NonNull
static <K> @NonNull ExecutionFlow<K> error(@NonNull
 @NonNull Throwable e)

Create a simple flow representing an error.

Type Parameters:

K - The value type

Parameters:

e - The exception

Returns:

a new flow

empty

@NonNull
static <T> @NonNull ExecutionFlow<T> empty()

Create a simple flow representing an empty state.

Type Parameters:

T - The flow value type

Returns:

a new flow

async

@NonNull
static <T> @NonNull ExecutionFlow<T> async(@NonNull
 @NonNull Executor executor,
 @NonNull
 @NonNull Supplier<? extends ExecutionFlow<T>> supplier)

Create a flow by invoking a supplier asynchronously.

Type Parameters:

T - The flow value type

Parameters:

executor - The executor

supplier - The supplier

Returns:

a new flow

map

@NonNull
<R> @NonNull ExecutionFlow<R> map(@NonNull
 @NonNull Function<? super T,? extends R> transformer)

Map a not-empty value.

Type Parameters:

R - New value Type

Parameters:

transformer - The value transformer

Returns:

a new flow

flatMap

@NonNull
<R> @NonNull ExecutionFlow<R> flatMap(@NonNull
 @NonNull Function<? super T,? extends ExecutionFlow<? extends R>> transformer)

Map a not-empty value to a new flow.

Type Parameters:

R - New value Type

Parameters:

transformer - The value transformer

Returns:

a new flow

then

@NonNull
<R> @NonNull ExecutionFlow<R> then(@NonNull
 @NonNull Supplier<? extends ExecutionFlow<? extends R>> supplier)

Supply a new flow after the existing flow value is resolved.

Type Parameters:

R - New value Type

Parameters:

supplier - The supplier

Returns:

a new flow

onErrorResume

@NonNull
@NonNull ExecutionFlow<T> onErrorResume(@NonNull
 @NonNull Function<? super Throwable,? extends ExecutionFlow<? extends T>> fallback)

Supply a new flow if the existing flow is erroneous.

Parameters:

fallback - The fallback

Returns:

a new flow

putInContext

@NonNull
@NonNull ExecutionFlow<T> putInContext(@NonNull
 @NonNull String key,
 @NonNull
 @NonNull Object value)

Store a contextual value.

Parameters:

key - The key

value - The value

Returns:

a new flow

putInContextIfAbsent

@NonNull
default @NonNull ExecutionFlow<T> putInContextIfAbsent(@NonNull
 @NonNull String key,
 @NonNull
 @NonNull Object value)

Store a contextual value if it is absent.

Parameters:

key - The key

value - The value

Returns:

a new flow

Since:

4.8.0

onComplete

void onComplete(@NonNull
 @NonNull BiConsumer<? super T,Throwable> fn)

Invokes a provided function when the flow is resolved, or immediately if it is already done.

Parameters:

fn - The function

completeTo

void completeTo(@NonNull
 @NonNull CompletableFuture<T> completableFuture)

Completes the flow to the completable future.

Parameters:

completableFuture - The completable future

Since:

4.8

timeout

@NonNull
default @NonNull ExecutionFlow<T> timeout(@NonNull
 @NonNull Duration timeout,
 @NonNull
 @NonNull ScheduledExecutorService scheduler,
 @Nullable
 @Nullable BiConsumer<T,Throwable> onDiscard)

Create a new ExecutionFlow that either returns the same result or, if the timeout expires before the result is received, a TimeoutException.

Parameters:

timeout - The timeout

scheduler - Scheduler to schedule the timeout task

onDiscard - An optional consumer to be called on the value of this flow if the flow completes after the timeout has expired and thus the value is discarded

Returns:

A new flow that will produce either the same value or a TimeoutException

tryComplete

@Nullable
@Nullable ImperativeExecutionFlow<T> tryComplete()

Create an ImperativeExecutionFlow from this execution flow, if possible. The flow will have its result immediately available.

Returns:

The imperative flow, or null if this flow is not complete or does not support this operation

tryCompleteValue

@Nullable
default T tryCompleteValue()

Alternative to tryComplete() which will unwrap the flow's value.

Returns:

The imperative flow then returns its value, or null if this flow is not complete or does not support this operation

Since:

4.3

tryCompleteError

@Nullable
default @Nullable Throwable tryCompleteError()

Alternative to tryComplete() which will unwrap the flow's error.

Returns:

The imperative flow then returns its error, or null if this flow is not complete or does not support this operation

Since:

4.3

toCompletableFuture

@NonNull
default @NonNull CompletableFuture<T> toCompletableFuture()

Converts the existing flow into the completable future.

Returns:

a CompletableFuture that represents the state if this flow.

cancel

default void cancel()

Send an optional hint to the upstream producer that the result of this flow is no longer needed and can be discarded. This is an optional operation, and has no effect if the flow has already completed. After a cancellation, a flow might never complete.

If this flow contains a resource that needs to be cleaned up (e.g. an InputStream), the caller should still add a completion listener for cleanup, in case the upstream producer does not support cancellation or has already submitted the result.

Since:

4.8.0