private NodeCache makeNodeCache(final ServiceInstance<T> instance) {
if (!watchInstances) {
return null;
}
final NodeCache nodeCache =
new NodeCache(client, pathForInstance(instance.getName(), instance.getId()));
try {
nodeCache.start(true);
} catch (Exception e) {
log.error("Could not start node cache for: " + instance, e);
}
NodeCacheListener listener =
new NodeCacheListener() {
@Override
public void nodeChanged() throws Exception {
if (nodeCache.getCurrentData() != null) {
ServiceInstance<T> newInstance =
serializer.deserialize(nodeCache.getCurrentData().getData());
Entry<T> entry = services.get(newInstance.getId());
if (entry != null) {
synchronized (entry) {
entry.service = newInstance;
}
}
} else {
log.warn("Instance data has been deleted for: " + instance);
}
}
};
nodeCache.getListenable().addListener(listener);
return nodeCache;
}
@Override
public void updateService(final ServiceInstance<T> service) throws Exception {
Entry<T> entry = services.get(service.getId());
if (entry == null) {
throw new Exception("Service not registered: " + service);
}
synchronized (entry) {
entry.service = service;
byte[] bytes = serializer.serialize(service);
String path = pathForInstance(service.getName(), service.getId());
client.setData().forPath(path, bytes);
}
}
@VisibleForTesting
protected void internalRegisterService(ServiceInstance<T> service) throws Exception {
byte[] bytes = serializer.serialize(service);
String path = pathForInstance(service.getName(), service.getId());
final int MAX_TRIES = 2;
boolean isDone = false;
for (int i = 0; !isDone && (i < MAX_TRIES); ++i) {
try {
CreateMode mode =
(service.getServiceType() == ServiceType.DYNAMIC)
? CreateMode.EPHEMERAL
: CreateMode.PERSISTENT;
client.create().creatingParentsIfNeeded().withMode(mode).forPath(path, bytes);
isDone = true;
} catch (KeeperException.NodeExistsException e) {
client.delete().forPath(path); // must delete then re-create so that watchers fire
}
}
}