Develop

[lyy4j]

producer client of ConsistentHash selector:
here the code:

public class SelectMessageQueueByConsistentHash implements MessageQueueSelector {

private volatile SortedMap<Integer, String> virtualNodes =
        new TreeMap<Integer, String>();

private static final int VIRTUAL_NODES = 100;

private volatile HashMap<String, MessageQueue> idToQueueMap = new HashMap<String, MessageQueue>();

private Object idToQueueMapMonitor = new Object();

@Override
public MessageQueue select(List<MessageQueue> mqs, Message msg, Object arg) {
    if (queueChange(mqs)) {
        synchronized (this.idToQueueMapMonitor) {
            if (queueChange(mqs)) {
                reloadConsistentHash(mqs);
            }
        }
    }
    String uniqueQueueId = getMsgQueue(arg.toString());
    MessageQueue messageQueue = idToQueueMap.get(uniqueQueueId);
    return messageQueue;
}

private boolean queueChange(List<MessageQueue> mqs) {
    if (mqs.size() != this.idToQueueMap.size()) {
        return true;
    }

    for (MessageQueue queue : mqs) {
        String id = queue.getTopic() + "_" + queue.getBrokerName() + "_" + queue.getQueueId();
        if (!this.idToQueueMap.containsKey(id)) {
            return true;
        }
    }

    return false;
}

private String getMsgQueue(String node) {

    int hash = getHash(node);
    SortedMap<Integer, String> subMap =
            virtualNodes.tailMap(hash);

    Integer i;
    String virtualNode;

    if (subMap.size() == 0) { 
        i = virtualNodes.firstKey();
        virtualNode = virtualNodes.get(i);
    } else {
        i = subMap.firstKey();
        virtualNode = subMap.get(i);
    }


    String result = virtualNode.substring(0, virtualNode.indexOf("&&"));
    return result;
}

private int getHash(String str) {
    final int p = 16777619;
    int hash = (int) 2166136261L;
    for (int i = 0; i < str.length(); i++)
        hash = (hash ^ str.charAt(i)) * p;
    hash += hash << 13;
    hash ^= hash >> 7;
    hash += hash << 3;
    hash ^= hash >> 17;
    hash += hash << 5;

    if (hash < 0)
        hash = Math.abs(hash);
    return hash;
}

private void reloadConsistentHash(List<MessageQueue> mqs) {
    idToQueueMap.clear();
    for (MessageQueue messageQueue : mqs) {
        String id = messageQueue.getTopic() + "_" + messageQueue.getBrokerName() + "_" + messageQueue.getQueueId();
        idToQueueMap.put(id, messageQueue);
    }

    virtualNodes.clear();

    for (String id : idToQueueMap.keySet()) {
        for (int i = 0; i < VIRTUAL_NODES; i++) {
            String virtualNodeName = id + "&&VN" + String.valueOf(i);
            int hash = getHash(virtualNodeName);
            virtualNodes.put(hash, virtualNodeName);
        }
    }
}

}

[vsair]

I think you may have a look at the contributor's guideline.

http://rocketmq.apache.org/docs/pull-request/

[coveralls]

Coverage decreased (-0.03%) to 39.09% when pulling 9bb6eae on develop into d414920 on master.

[coveralls]

Coverage decreased (-0.03%) to 39.09% when pulling 9bb6eae on develop into d414920 on master.

[coveralls]

Coverage decreased (-0.03%) to 39.09% when pulling 9bb6eae on develop into d414920 on master.