RandomRule policy modification

[mujun0312]

In the RandomRule's choose method, it use upList to get server, the index of the server come from "ThreadLocalRandom.current().nextInt(serverCount)", so the serverCount is the number of all server. But to get the reachable server is to use upList like this:

It seems to happen that the index(come from index = ThreadLocalRandom.current().nextInt(serverCount) ) is larger than the upList's size.

[mujun0312]

@qiangdavidliu Could you please review?

[yyvess]

Server should not be selected on upList ?

int index = chooseRandomInt(upCount);
server = upList.get(index);

[mujun0312]

Yes, server should be selected on upList, but the index should not be chosen from serverCount, it may be greater than upList.size()

[yyvess]

Check upCount isn't sufficient ?

[mujun0312]

If the server that is reachable is down, then the upCount is 0

[broncho]

just use reachable servers.

public Server choose(ILoadBalancer lb, Object key) {
        if (lb == null) {
            return null;
        }
        Server server = null;

        while (server == null) {
            if (Thread.interrupted()) {
                return null;
            }
            List<Server> upList = lb.getReachableServers();
            List<Server> allList = lb.getAllServers();

            int serverCount = allList.size();
            int upServerCount = upList.size();
            if (serverCount == 0  || upServerCount  ==0 ) {
                /*
                 * No servers. End regardless of pass, because subsequent passes
                 * only get more restrictive.
                 */
                return null;
            }

           // int index = chooseRandomInt(serverCount);
            //server = upList.get(index);
            
            int index = chooseRandomInt(upServerCount );
            server = upList.get(index);  

            if (server == null) {
                /*
                 * The only time this should happen is if the server list were
                 * somehow trimmed. This is a transient condition. Retry after
                 * yielding.
                 */
                Thread.yield();
                continue;
            }

            if (server.isAlive()) {
                return (server);
            }

            // Shouldn't actually happen.. but must be transient or a bug.
            server = null;
            Thread.yield();
        }

        return server;

    }