private ManagerElectionState Elect(CancellationToken cancellationToken)
{
var electResult = _election.Elect(cancellationToken);
var electState = electResult.State;
LogWriter.Write(string.Format("elect result: {0}, current manager: {1}", electResult.IsSuccess, electState.CurrentManagerId));
ManagerElectCompletedEventHandler?.Invoke(electResult);
return(electState);
}
/// <summary>
/// 监控Manager选举
/// </summary>
public void Watch(CancellationToken cancellationToken = default(CancellationToken))
{
var key = GetManagerKey();
LogWriter.Write("start first manager election");
// 上来就先选举一次，看看结果，以启动Manager或Worker剧本
var electResult = Elect(out ulong modifyIndex, cancellationToken);
ulong waitIndex = modifyIndex++;
ManagerElectCompletedEventHandler?.Invoke(electResult, _managerId);
var waitTime = _defaultWatchInterval;
var offlineConfirmAmount = _defaultOfflineConfirmAmount;
do
{
cancellationToken.ThrowIfCancellationRequested();
try
{
LogWriter.Write("start manager watch query", LogLevel.Debug);
// 阻塞查询
var kv = ConsulKV.BlockGet(key, waitTime, waitIndex, cancellationToken);
// 可能Key被删除了
if (kv == null)
{
LogWriter.Write("manager is not exists, start election right away");
electResult = Elect(out modifyIndex, cancellationToken);
waitIndex = modifyIndex++;
LogWriter.Write(string.Format("elect result: {0}, current manager: {1}", electResult, _managerId));
ManagerElectCompletedEventHandler?.Invoke(electResult, _managerId);
}
else
{
waitIndex = kv.ModifyIndex++;
// 如果Session为空，则说明Manager下线了
// 但是这时候可能Manager出现了闪断，为了减少Manager重新选举导致的处理工作，节点应该再确认两次，
// 如果在确认过程中Manager又上线了，则应该优先再次当选为Manager，减少不必要的麻烦
if (string.IsNullOrWhiteSpace(kv.Session))
{
LogWriter.Write(string.Format("manager session is empty, last manager is {0}", Encoding.UTF8.GetString(kv.Value)));
// 如果上一个Manager是当前成员，则马上重试
if (Encoding.UTF8.GetString(kv.Value) == _memberId)
{
LogWriter.Write("last manager is me, start election right away");
electResult = Elect(out modifyIndex, cancellationToken);
waitIndex = modifyIndex++;
LogWriter.Write(string.Format("elect result: {0}, current manager: {1}", electResult, _managerId));
ManagerElectCompletedEventHandler?.Invoke(electResult, _managerId);
}
else
{
if (offlineConfirmAmount == 0)
{
LogWriter.Write("last manager not wake for a long time, start election right away", LogLevel.Info);
electResult = Elect(out modifyIndex, cancellationToken);
waitIndex = modifyIndex++;
LogWriter.Write(string.Format("elect result: {0}, current manager: {1}", electResult, _managerId));
ManagerElectCompletedEventHandler?.Invoke(electResult, _managerId);
}
else
{
LogWriter.Write("wait last manager ...", LogLevel.Info);
waitTime = _confirmWatchInterval;
offlineConfirmAmount--;
continue;
}
}
}
}
offlineConfirmAmount = _defaultOfflineConfirmAmount;
waitTime = _defaultWatchInterval;
}
catch (Exception ex)
{
LogWriter.Write("Manager选举监控异常", ex);
Thread.Sleep(3000);
}
}while (true);
}
