commit | 6720f35beb8718ae39018211f33bbff2ac782fb6 | [log] [tgz] |
---|---|---|
author | Edward Capriolo <edlinuxguru@gmail.com> | Tue Jan 03 15:25:29 2017 -0500 |
committer | Edward Capriolo <edlinuxguru@gmail.com> | Tue Jan 03 15:25:29 2017 -0500 |
tree | 969ffe81b51ea23d9bac50b0d1b4fc4008d5b28a | |
parent | 042b26f632c1712dfb5ff9c2542501656f449b02 [diff] |
[maven-release-plugin] prepare for next development iteration
Gossip protocol is a method for a group of nodes to discover and check the liveliness of a cluster. More information can be found at http://en.wikipedia.org/wiki/Gossip_protocol.
The original implementation was forked from https://code.google.com/p/java-gossip/. Several bug fixes and changes have already been added.
To gossip you need one or more seed nodes. Seed is just a list of places to initially connect to.
GossipSettings settings = new GossipSettings(); int seedNodes = 3; List<GossipMember> startupMembers = new ArrayList<>(); for (int i = 1; i < seedNodes+1; ++i) { startupMembers.add(new RemoteGossipMember("127.0.0." + i, 2000, i + "")); }
Here we start five gossip processes and check that they discover each other. (Normally these are on different hosts but here we give each process a distinct local ip.
List<GossipService> clients = new ArrayList<>(); int clusterMembers = 5; for (int i = 1; i < clusterMembers+1; ++i) { GossipService gossipService = new GossipService("127.0.0." + i, 2000, i + "", LogLevel.DEBUG, startupMembers, settings, null); clients.add(gossipService); gossipService.start(); }
Later we can check that the nodes discover each other
Thread.sleep(10000); for (int i = 0; i < clusterMembers; ++i) { Assert.assertEquals(4, clients.get(i).get_gossipManager().getMemberList().size()); }
For a very simple client setup with a settings file you first need a JSON file such as:
[{ "id":"419af818-0114-4c7b-8fdb-952915335ce4", "port":50001, "gossip_interval":1000, "cleanup_interval":10000, "members":[ {"host":"127.0.0.1", "port":50000} ] }]
where:
id
- is a unique id for this node (you can use any string, but above we use a UUID)port
- the port to use on the default adapter on the node's machinegossip_interval
- how often (in milliseconds) to gossip list of members to other node(s)cleanup_interval
- when to remove ‘dead’ nodes (in milliseconds)members
- initial seed nodesThen starting a local node is as simple as:
GossipService gossipService = new GossipService( StartupSettings.fromJSONFile( "node_settings.json" ) ); gossipService.start();
And then when all is done, shutdown with:
gossipService.shutdown();
The status can be polled using the getters that return immutable lists.
List<LocalGossipMember> getMemberList() public List<LocalGossipMember> getDeadMembers()
These can be accessed from the GossipManager
on your GossipService
, e.g: gossipService.get_gossipManager().getMemberList();
Users can also attach an event listener:
GossipService gossipService = new GossipService("127.0.0." + i, 2000, i + "", LogLevel.DEBUG, startupMembers, settings, new GossipListener(){ @Override public void gossipEvent(GossipMember member, GossipState state) { System.out.println(member+" "+ state); } });