创建与队列的BackgroundWorker [英] Creating BackgroundWorker with Queue

问题描述

我需要创建队列和BackgroundWorker的使用。所以，我可以添加操作和当一个人做旁边在后台正在启动。我发现这个代码由谷歌：

I need to create queue and use it with BackgroundWorker. So I can add operations and when one is done next is starting in background. I found this code by google:

public class QueuedBackgroundWorker<T>
{
    public void QueueWorkItem(
        Queue queue,
        T inputArgument,
        Func<T> doWork,
        Action workerCompleted)
    {
        if (queue == null) throw new ArgumentNullException("queue");

        BackgroundWorker bw = new BackgroundWorker();
        bw.WorkerReportsProgress = false;
        bw.WorkerSupportsCancellation = false;
        bw.DoWork += (sender, args) =>
        {
            if (doWork != null)
            {
                args.Result = doWork(new DoWorkArgument<T>((T)args.Argument));
            }
        };
        bw.RunWorkerCompleted += (sender, args) =>
        {
            if (workerCompleted != null)
            {
                workerCompleted(new WorkerResult<T>((T)args.Result, args.Error));
            }
            queue.Dequeue();
            if (queue.Count > 0)
            {
                QueueItem<T> nextItem = queue.Peek() as QueueItem<T>;
                nextItem.BackgroundWorker.RunWorkerAsync(nextItem.Argument);
            }
        };

        queue.Enqueue(new QueueItem<T>(bw, inputArgument));
        if (queue.Count == 1)
        {
            QueueItem<T> nextItem = queue.Peek() as QueueItem<T>;
            nextItem.BackgroundWorker.RunWorkerAsync(nextItem.Argument);
        }
    }
}

public class DoWorkArgument<T>
{
    public DoWorkArgument(T argument)
    {
        this.Argument = argument;
    }
    public T Argument { get; private set; }
}

public class WorkerResult<T>
{
    public WorkerResult(T result, Exception error)
    {
        this.Result = result;
        this.Error = error;
    }

    public T Result { get; private set; }
    public Exception Error { get; private set; }
}

public class QueueItem<T>
{
    public QueueItem(BackgroundWorker backgroundWorker, T argument)
    {
        this.BackgroundWorker = backgroundWorker;
        this.Argument = argument;
    }

    public T Argument { get; private set; }
    public BackgroundWorker BackgroundWorker { get; private set; }
}

但我有问题的doWork和workerCompleted。我得到错误：

But I have problem with doWork and workerCompleted. I get error:

代表'功能'不带1个参数

Delegate 'Func' does not take 1 arguments

我怎样才能解决这个问题？我应该如何改变参数？谢谢

How can I fix this? How should I change parameters? Thanks

推荐答案

下面是一个更短的方法，你想要做什么：

Here's a much shorter method that does what you want:

public class BackgroundQueue
{
    private Task previousTask = Task.FromResult(true);
    private object key = new object();
    public Task QueueTask(Action action)
    {
        lock (key)
        {
            previousTask = previousTask.ContinueWith(t => action()
                , CancellationToken.None
                , TaskContinuationOptions.None
                , TaskScheduler.Default);
            return previousTask;
        }
    }

    public Task<T> QueueTask<T>(Func<T> work)
    {
        lock (key)
        {
            var task = previousTask.ContinueWith(t => work()
                , CancellationToken.None
                , TaskContinuationOptions.None
                , TaskScheduler.Default);
            previousTask = task;
            return task;
        }
    }
}

通过增加每个新行动可以确保只有一次是在工作，为下一个项目以前的延续将不会启动，直到上一个项目完成后，可以确保没有线程坐在身边时，有什么可工作在怠速和你确保他们都为了完成。

By adding each new action as a continuation of the previous you ensure that only one is worked on at a time, as the next item won't start until the previous item is finished, you ensure that there is no thread sitting around idling when there is nothing to be worked on, and you ensure they're all done in order.

另外请注意，如果你只会认为你需要一个队列，并没有任何数字，你可以做所有成员静态的，但是这取决于你。

Also note that if you only ever think you'll need one queue, and not any number, you could make all of the members static, but that's up to you.

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