Class MulticastDiscovery

java.lang.Object

com.loomcache.server.discovery.MulticastDiscovery

All Implemented Interfaces:

DiscoveryStrategy

public class MulticastDiscovery
extends Object
implements DiscoveryStrategy

UDP multicast-based discovery for local area networks.

Each node periodically announces itself to a multicast group. Announcements contain: nodeId,host,port

Configuration: - Multicast group: 239.0.0.1:5555 (configurable) - Announcement interval: 5 seconds - Peer timeout: 30 seconds (peers expire if no announcement received)

Uses virtual threads for announcement and listening. Thread-safe with ConcurrentHashMap for peer tracking.

Constructor Summary

Constructors

Constructor	Description
MulticastDiscovery(String nodeId, String host, int port)	Create a multicast discovery strategy.
MulticastDiscovery(String nodeId, String host, int port, String multicastGroup, int multicastPort)	Create a multicast discovery strategy with custom multicast group.

Method Summary

Modifier and Type	Method	Description
List<PeerAddress>	discoverPeers()	Discover available peers.
String	getName()	Get the name of this discovery strategy.
void	start()	Start the discovery strategy.
void	stop()	Stop the discovery strategy and release resources.

Methods inherited from class Object

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

Constructor Details

MulticastDiscovery

public MulticastDiscovery(String nodeId,
 String host,
 int port)

Create a multicast discovery strategy.

Parameters:

nodeId - this node's identifier

host - this node's host address

port - this node's port

MulticastDiscovery

public MulticastDiscovery(String nodeId,
 String host,
 int port,
 String multicastGroup,
 int multicastPort)

Create a multicast discovery strategy with custom multicast group.

Parameters:

nodeId - this node's identifier

host - this node's host address

port - this node's port

multicastGroup - multicast group IP (e.g., "239.0.0.1")

multicastPort - multicast port (e.g., 5555)

Method Details

start

public void start()
           throws Exception

Description copied from interface: DiscoveryStrategy

Start the discovery strategy.

Initializes the discovery mechanism and starts any background threads or I/O operations (e.g., watching files, listening to multicast, resolving DNS). Implementations must handle errors gracefully and should not leave resources in an inconsistent state if startup fails.

Specified by:

start in interface DiscoveryStrategy

Throws:

Exception - if startup fails; specific exceptions depend on implementation

stop

public void stop()

Description copied from interface: DiscoveryStrategy

Stop the discovery strategy and release resources.

Cleanly shuts down the discovery mechanism, including stopping any background threads and closing I/O resources. Safe to call multiple times and must be idempotent (calling twice should have no additional effect).

Specified by:

stop in interface DiscoveryStrategy

discoverPeers

public List<PeerAddress> discoverPeers()

Description copied from interface: DiscoveryStrategy

Discover available peers.

Returns a snapshot of currently known peers. If no peers are available, an empty list is returned (not null). The returned list is mutable and modifications should not affect internal strategy state.

Specified by:

discoverPeers in interface DiscoveryStrategy

Returns:

list of discovered peer addresses; empty list if none available

getName

public String getName()

Description copied from interface: DiscoveryStrategy

Get the name of this discovery strategy.

Used for logging, metrics, and debugging purposes.

Specified by:

getName in interface DiscoveryStrategy

Returns:

human-readable strategy name (e.g., "FileBasedDiscovery", "MulticastDiscovery")