Package org.axonframework.messaging.core

Class MessageStreamUtils

java.lang.Object

org.axonframework.messaging.core.MessageStreamUtils

@Internal
public abstract class MessageStreamUtils
extends Object

Utility methods to work with MessageStreams.

Since:

5.0.0

Author:

Allard Buijze

Field Summary

Fields

Modifier and Type	Field	Description
static final Runnable	NO_OP_CALLBACK	A reusable no-operation Runnable instance.

Method Summary

Modifier and Type	Method	Description
static <M extends Message, R> CompletableFuture<@Nullable R>	reduce(MessageStream<M> source, @Nullable R identity, BiFunction<@Nullable R,? super MessageStream.Entry<M>,@Nullable R> accumulator)	Returns a CompletableFuture that completes with the given reduction of messages read from the source.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

NO_OP_CALLBACK

public static final Runnable NO_OP_CALLBACK

A reusable no-operation Runnable instance.

This constant can be used in contexts where a non-null callback is required, but no specific action needs to be performed. When executed, it performs no operation and immediately returns.

Method Details

reduce

public static <M extends Message,
R>
CompletableFuture<@Nullable R> reduce(MessageStream<M> source,
 @Nullable R identity,
 BiFunction<@Nullable R,? super MessageStream.Entry<M>,@Nullable R> accumulator)

Returns a CompletableFuture that completes with the given reduction of messages read from the source. The reduction is computed by applying the given accumulator function on the result of the previous invocation in combination with each entry returned by the given source. The very first invocation of the accumulator function is given the identity.

If the given source completes normally without producing any entries, the returned CompletableFuture completes with the given identity.

If the given source completes with an error, whether entries have been produced or not, the returned CompletableFuture completes exceptionally with that error.

Multi-threading
The accumulator function is invoked either on the thread calling this method, when entries are immediately available for reading, or on the thread on which entries are reported to be available for reading from the given source. The accumulator function does not need to be thread-safe.

Type Parameters:

M - The type of Message to consume from the MessageStream.

R - The type of result expected from the reduction operation.

Parameters:

source - The MessageStream to consume messages from.

identity - The initial value to use for the accumulation.

accumulator - The function to combine the current reduction result with the next entry from the MessageStream.

Returns:

A CompletableFuture that completes with the result of the reduction operation.