我有一个ReliableQueue<MyTask>
被排入不同范围的队列,并且我正在将事务中的任务出列,然后想对每个任务运行一些长时间运行的计算。
这里的问题是,如果我的队列事务被中止,我不想丢失长计算的实例。它将继续在后台独立运行,我只想在我重试处理任务后检查它是否完成。
代码段:
public void protected override async Task RunAsync(CancellationToken cancellationToken)
{
var queue = await StateManager.GetOrAddAsync<IReliableQueue<MyTask>>(...);
while(!cancellationToken.IsCancellationRequested)
{
using (var transaction = ...)
{
var myTaskConditional = await queue.TryDequeueAsync(transaction);
if (!myTaskConditional.HasValue)
{
break;
}
await DoLongProcessing(myTaskConditional)
await transaction.CommitAsync();
}
}
}
private async void DoLongProcessing(MyTask myTask) {
var dict = await StateManager.GetOrAddAsync<IReliableDictionary<Guid,Guid>>(...);
Conditional<Guid> guidConditional;
using (var transaction = ...)
{
guidConditional = await dict.TryGetValueAsync(myTask.TaskGuid);
if (guidConditional.HasValue) {
await transaction.CommitAsync();
// continue handling knowing we already started, continue to wait for
await WaitForClaulcationFinish(guidConditional.Value);
}
else {
// start handling knowing we never handled this task, create new guid and store it in dict
var runGuid = await StartRunningCalculation(runGuid);
await dict.AddAsync(myTask.TaskGuid, runGuid);
await transaction.CommitAsync();
await WaitForClaulcationFinish(runGuid);
}
}
}
我的担忧:我正在使用嵌套事务,不建议这样做。
如果我仅将事务用于ReliableQueue
或ReliableDictionary
单独使用,这里是否真的存在死锁的风险?
对于我想要实现的目标,是否有更好的设计?