Package io.fluxcapacitor.javaclient.tracking.client

Class InMemoryMessageStore

java.lang.Object

io.fluxcapacitor.javaclient.tracking.client.InMemoryMessageStore

All Implemented Interfaces:

Monitored<List<SerializedMessage>>, HasMessageStore, MessageStore, AutoCloseable

Direct Known Subclasses:

InMemoryEventStore, InMemoryScheduleStore

public class InMemoryMessageStore
extends Object
implements MessageStore

An in-memory implementation of the MessageStore interface for storing SerializedMessages without external persistence.

This store underpins both local tracking (via LocalTrackingClient) and local publishing (via in-memory GatewayClient) in test and development environments.

Behavior

• Messages are assigned a unique, incrementing index upon append if none is present.
• Stored messages are retained in memory using a ConcurrentSkipListMap keyed by index.
• Supports expiration via retentionTime, with periodic purging during appends.
• Supports message monitors that are notified after every append.

Thread Safety

• Append and monitor notifications are synchronized to preserve consistency across batch inserts.
• Message storage is based on concurrent data structures, safe for multi-threaded access.
• Monitors use a CopyOnWriteArraySet for thread-safe iteration and updates.

Use Cases

• Unit and integration tests for consumers, handlers, and gateways
• Simulating message flow in local environments without a Flux Capacitor backend
• Standalone tools that mock message streams

Message Expiration

• Expired messages are purged based on wall-clock time via FluxCapacitor.currentTime().
• The purge logic is triggered during each call to append(List) when a retention policy is set.

See Also:

• MessageStore
• LocalTrackingClient

Constructor Summary

Constructors

Constructor	Description
InMemoryMessageStore(MessageType messageType)

Method Summary

Modifier and Type	Method	Description
CompletableFuture<Void>	append(List<SerializedMessage> messages)	Appends a list of messages to the store.
void	close()	Default no-op close method.
protected Collection<SerializedMessage>	filterMessages(Collection<SerializedMessage> messages)
List<SerializedMessage>	getBatch(Long minIndex, int maxSize, boolean inclusive)	Retrieves a batch of messages starting from the given minIndex.
protected SerializedMessage	getMessage(long index)
void	notifyMonitors()
protected void	notifyMonitors(List<SerializedMessage> messages)
protected void	purgeExpiredMessages(Duration messageExpiration)
Registration	registerMonitor(Consumer<List<SerializedMessage>> monitor)	Registers a monitor that will be notified when an activity of type T occurs.
String	toString()

Methods inherited from class java.lang.Object

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

Methods inherited from interface io.fluxcapacitor.common.tracking.MessageStore

append, getBatch, getMessageStore, setRetentionTime, unwrap

Constructor Details

InMemoryMessageStore

public InMemoryMessageStore(MessageType messageType)

Method Details

append

public CompletableFuture<Void> append(List<SerializedMessage> messages)

Description copied from interface: MessageStore

Appends a list of messages to the store.

Specified by:

append in interface MessageStore

Parameters:

messages - messages to append

Returns:

a CompletableFuture that completes when the messages have been successfully appended

getBatch

public List<SerializedMessage> getBatch(Long minIndex,
 int maxSize,
 boolean inclusive)

Description copied from interface: MessageStore

Retrieves a batch of messages starting from the given minIndex.

Specified by:

getBatch in interface MessageStore

Parameters:

minIndex - minimum message index to start from

maxSize - maximum number of messages to retrieve

inclusive - whether to include the message at minIndex

Returns:

a list of SerializedMessage instances

notifyMonitors

public void notifyMonitors()

notifyMonitors

protected void notifyMonitors(List<SerializedMessage> messages)

purgeExpiredMessages

protected void purgeExpiredMessages(Duration messageExpiration)

filterMessages

protected Collection<SerializedMessage> filterMessages(Collection<SerializedMessage> messages)

getMessage

protected SerializedMessage getMessage(long index)

registerMonitor

public Registration registerMonitor(Consumer<List<SerializedMessage>> monitor)

Description copied from interface: Monitored

Registers a monitor that will be notified when an activity of type T occurs.

Specified by:

registerMonitor in interface Monitored<List<SerializedMessage>>

Parameters:

monitor - the callback to invoke with each observed value

Returns:

a Registration that can be used to cancel the monitoring

close

public void close()

Description copied from interface: MessageStore

Default no-op close method. Override if resources need cleanup.

Specified by:

close in interface AutoCloseable

Specified by:

close in interface MessageStore

toString

public String toString()

Overrides:

toString in class Object