Concurrency problem in NettyTransportClient of sentinel-cluster-client-default

[XHao]

// https://github.com/alibaba/Sentinel/blob/bef6574734bc75953202079dc0a44aa5dff78157/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/NettyTransportClient.java#L222

channel.writeAndFlush(request);

ChannelPromise promise = channel.newPromise();
TokenClientPromiseHolder.putPromise(xid, promise);  // 1、should before writeAndFlush to avoid concurrency problem

if (!promise.await(ClusterClientConfigManager.getRequestTimeout())) {
    throw new SentinelClusterException(ClusterErrorMessages.REQUEST_TIME_OUT); // 3、timeout exception
}

// https://github.com/alibaba/Sentinel/blob/bef6574734bc75953202079dc0a44aa5dff78157/sentinel-cluster/sentinel-cluster-client-default/src/main/java/com/alibaba/csp/sentinel/cluster/client/handler/TokenClientPromiseHolder.java#L47

if (!PROMISE_MAP.containsKey(xid)) { 
     return false;   // 2、we can't complete the promise
}