using System;
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using System.Collections.Generic;
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using System.Text;
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using System.Threading;
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namespace Top.Api.Cluster
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{
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public sealed class ClusterManager
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{
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private static readonly Random random = new Random();
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private static readonly Object initLock = new Object();
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private static volatile DnsConfig dnsConfig = null;
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private static volatile Thread refreshThread = null;
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public static T GetElementByWeight<T>(List<T> list) where T : Weightable
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{
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T selected = null;
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double totalWeight = 0d;
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foreach (T element in list)
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{
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double r = random.NextDouble() * (element.Weight + totalWeight);
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if (r >= totalWeight)
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{
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selected = element;
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}
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totalWeight += element.Weight;
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}
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return selected;
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}
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public static DnsConfig GetDnsConfigFromCache()
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{
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return dnsConfig;
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}
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public static void InitRefreshThread(ITopClient client)
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{
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if (refreshThread == null)
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{
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lock (initLock)
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{
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if (refreshThread == null)
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{
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try
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{
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DnsConfig remoteConfig = GetDnsConfigFromTop(client);
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if (dnsConfig == null)
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{
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dnsConfig = remoteConfig;
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}
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else if (remoteConfig != null && remoteConfig.GetVersion() > dnsConfig.GetVersion())
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{
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dnsConfig = remoteConfig;
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}
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}
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catch (TopException e)
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{
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if ("22".Equals(e.ErrorCode))
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{
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return; // 如果HTTP DNS服务不存在，则退出守护线程
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}
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}
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refreshThread = new Thread(o =>
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{
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while (true)
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{
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try
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{
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Thread.Sleep(dnsConfig.GetRefreshInterval() * 60 * 1000);
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dnsConfig = GetDnsConfigFromTop(client);
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}
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catch (Exception e)
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{
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Console.WriteLine(e.StackTrace);
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Thread.Sleep(3 * 1000); // 出错则过3秒重试
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}
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}
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});
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refreshThread.IsBackground = true;
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refreshThread.Name = "HTTP_DNS_REFRESH_THREAD";
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refreshThread.Start();
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}
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}
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}
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}
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private static DnsConfig GetDnsConfigFromTop(ITopClient client)
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{
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HttpdnsGetRequest req = new HttpdnsGetRequest();
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HttpdnsGetResponse rsp = client.Execute(req);
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if (!rsp.IsError)
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{
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return DnsConfig.parse(rsp.Result);
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}
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else
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{
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throw new TopException(rsp.ErrCode, rsp.ErrMsg);
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}
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}
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}
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}
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