Failover locator in spymemcached

FailoverNodeLocator.java

public class FailoverNodeLocator implements NodeLocator {

	private MemcachedNode[] nodes;

	public FailoverNodeLocator(List<MemcachedNode> n) {
		assert n.size() > 1;
		nodes = n.toArray(new MemcachedNode[n.size()]);
	}

	public FailoverNodeLocator(MemcachedNode[] n) {
		nodes = n;
	}

	@Override
	public MemcachedNode getPrimary(String k) {
		return nodes[0];
	}

	@Override
	public Iterator<MemcachedNode> getSequence(String k) {
		return new NodeIterator(getServerForKey(k));
	}

	private int getServerForKey(String key) {
		return 0;
	}

	@Override
	public Collection<MemcachedNode> getAll() {
		return Arrays.asList(nodes);
	}

	@Override
	public NodeLocator getReadonlyCopy() {
		MemcachedNode[] n = new MemcachedNode[nodes.length];
		for (int i = 0; i < nodes.length; i++) {
			n[i] = new MemcachedNodeROImpl(nodes[i]);
		}
		return new FailoverNodeLocator(n);
	}

	@Override
	public void updateLocator(List<MemcachedNode> newNodes) {
	    this.nodes = newNodes.toArray(new MemcachedNode[newNodes.size()]);
	}

	class NodeIterator implements Iterator<MemcachedNode> {

		private final int start;
		private int next = 0;

		public NodeIterator(int keyStart) {
			start = keyStart;
			next = start;
			computeNext();
			assert next >= 0 || nodes.length == 1 : "Starting sequence at " + start + " of " + nodes.length + " next is " + next;
		}

		public boolean hasNext() {
			return next >= 0;
		}

		private void computeNext() {
			if (++next >= nodes.length) {
				next = 0;
			}
			if (next == start) {
				next = -1;
			}
		}

		public MemcachedNode next() {
			try {
				return nodes[next];
			} finally {
				computeNext();
			}
		}

		public void remove() {
			throw new UnsupportedOperationException("Can't remove a node");
		}
	}
}