这是一个正确的.NET 4实施.NET 4.5的WhenAll? [英] Is this a correct .NET 4 implementation for .NET 4.5's WhenAll?
问题描述
我使用SignalR。在集线器的功能往往返回任务。我现在有将增加一堆组的连接功能。我想返回表示所有这些任务的任务。
我找到了一个完美的功能:Task.WhenAll。然而,这是.NET 4.5新功能,我仍然停留在.NET 4。
因此,我决定写我自己的版本,直到我们可以移动到.NET 4.5。因为经常有一些注意事项,当涉及到多线程(如线程池的东西),我不知道如果我的实现是正确的:
公共静态任务WhenAll(IEnumerable的<任务>任务)
{
返回Task.Factory.StartNew(()=> Task.WaitAll(tasks.ToArray()));
}
在功能上,它的工作原理我想,但我没有拿到额外的封锁螺纹新任务?或者,这是不可避免的?
编辑:
这里是我如何与SignalR使用它:
公共静态任务添加(这IGroupManager groupManager,字符串的ConnectionId,
的IEnumerable<串基团)
{
返回WhenAll(groups.Select(组=> groupManager.Add (ConnectionId之外组)));
}
您的解决方案将正常工作,但你说得对,它会阻塞线程的全部时间。
我觉得最简单的方法能够有效地实现 WhenAll()
在.NET 4.0是使用 ContinueWhenAll ()
。它执行当所有工作
期从集合完成一个动作,并返回一个工作
表示该动作。因为我们希望这一点工作
,我们不需要的动作,传递一个空的lambda将工作:
公共静态任务WhenAll(IEnumerable的<任务>任务)
{
返回Task.Factory.ContinueWhenAll(tasks.ToArray(),_ => {});
}
I am using SignalR. The function on the Hub often return a Task. I now have a function that will add a connection to a bunch of groups. I would like to return a Task that represents all of these Tasks.
I found a perfect function for that: Task.WhenAll. However this is a new function in .NET 4.5 and I am still stuck on .NET 4.
Hence I decided to write my own version of it until we can move to .NET 4.5. Because there are often some caveats when it comes to multithreading (e.g. thread pool stuff), I am not sure if my implementation is correct:
public static Task WhenAll(IEnumerable<Task> tasks)
{
return Task.Factory.StartNew(() => Task.WaitAll(tasks.ToArray()));
}
Functionally, it works I think, but don't I get an extra blocked thread for the new Task? Or is this unavoidable?
Edit: Here is how I would use it with SignalR:
public static Task Add(this IGroupManager groupManager, string connectionId,
IEnumerable<string> groups)
{
return WhenAll(groups.Select(group => groupManager.Add(connectionId, group)));
}
Your solution will work fine, but you're right that it would block a thread the whole time.
I think the simplest way to efficiently implement WhenAll()
on .Net 4.0 is to use ContinueWhenAll()
. It performs an action when all Task
s from a collection are finished and returns a Task
representing that action. Since we want just that Task
, we don't need the action, passing an empty lambda will work:
public static Task WhenAll(IEnumerable<Task> tasks)
{
return Task.Factory.ContinueWhenAll(tasks.ToArray(), _ => {});
}
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