org.axonframework.eventsourcing.eventstore

Class ConcatenatingDomainEventStream

java.lang.Object

org.axonframework.eventsourcing.eventstore.ConcatenatingDomainEventStream

All Implemented Interfaces:

Iterator<DomainEventMessage<?>>, DomainEventStream

public class ConcatenatingDomainEventStream
extends Object
implements DomainEventStream

DomainEventStream implementation that concatenates multiple streams, taking into account that some sequence numbers may appear in more than one stream.

Streams are consumed in the order provided, skipping events that have sequence numbers equal or lower than the last sequence number consumed from the previous stream.

This implementation is not thread safe. It should not be consumed by more than one thread at a time.

Since:

3.1.1

Constructor Summary

Constructors

Constructor and Description
ConcatenatingDomainEventStream(Collection<DomainEventStream> streams) Initialize the stream, concatenating the given streams.
ConcatenatingDomainEventStream(DomainEventStream... streams) Initialize the stream, concatenating the given streams.

Method Summary

Modifier and Type	Method and Description
Long	getLastSequenceNumber() Get the highest known sequence number in the upstream event entry stream.
boolean	hasNext() Returns true if the stream has more events, meaning that a call to next() will not result in an exception.
DomainEventMessage<?>	next() Returns the next events in the stream, if available.
DomainEventMessage<?>	peek() Returns the next events in the stream, if available, without moving the pointer forward.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.axonframework.eventsourcing.eventstore.DomainEventStream

asStream, concat, empty, filter, of, of, of, of, of, remove

Methods inherited from interface java.util.Iterator

forEachRemaining

Constructor Detail

ConcatenatingDomainEventStream

public ConcatenatingDomainEventStream(DomainEventStream... streams)

Initialize the stream, concatenating the given streams.

Parameters:

streams - The streams providing the elements to concatenate

ConcatenatingDomainEventStream

public ConcatenatingDomainEventStream(Collection<DomainEventStream> streams)

Initialize the stream, concatenating the given streams. The streams are consumed in the order the collection returns them.

Parameters:

streams - The streams providing the elements to concatenate

Method Detail

peek

public DomainEventMessage<?> peek()

Description copied from interface: DomainEventStream

Returns the next events in the stream, if available, without moving the pointer forward. Hence, a call to DomainEventStream.next() will return the same event as a call to peek(). Use hasNext() to obtain a guarantee about the availability of any next event.

If the pointer has reached the end of the stream, the behavior of this method is undefined. It could either return null, or throw an exception, depending on the actual implementation. Use DomainEventStream.hasNext() to confirm the existence of elements after the current pointer.

Specified by:

peek in interface DomainEventStream

Returns:

the next event in the stream.

hasNext

public boolean hasNext()

Description copied from interface: DomainEventStream

Returns true if the stream has more events, meaning that a call to next() will not result in an exception. If a call to this method returns false, there is no guarantee about the result of a consecutive call to next()

Specified by:

hasNext in interface Iterator<DomainEventMessage<?>>

Specified by:

hasNext in interface DomainEventStream

Returns:

true if the stream contains more events.

next

public DomainEventMessage<?> next()

Description copied from interface: DomainEventStream

Returns the next events in the stream, if available. Use hasNext() to obtain a guarantee about the availability of any next event. Each call to next() will forward the pointer to the next event in the stream.

If the pointer has reached the end of the stream, the behavior of this method is undefined. It could either return null, or throw an exception, depending on the actual implementation. Use DomainEventStream.hasNext() to confirm the existence of elements after the current pointer.

Specified by:

next in interface Iterator<DomainEventMessage<?>>

Specified by:

next in interface DomainEventStream

Returns:

the next event in the stream.

getLastSequenceNumber

public Long getLastSequenceNumber()

Description copied from interface: DomainEventStream

Get the highest known sequence number in the upstream event entry stream. Note that, as result of upcasting it is possible that the last event in this stream has a lower sequence number than that returned by this method.

To get the highest absolute sequence number of the underlying event entry stream make sure to iterate over all elements in the stream before calling this method.

If the stream is empty this method returns null.

Specified by:

getLastSequenceNumber in interface DomainEventStream

Returns:

the sequence number of the last known upstream event entry