c# - 使用队列创建 BackgroundWorker

Question

我需要创建队列并将其与 BackgroundWorker 一起使用。所以我可以添加操作，当一个操作完成时，下一步是在后台启动。我通过谷歌找到了这段代码:

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; }
}

但是我对 doWork 和 workerCompleted 有疑问。我收到错误:

Delegate 'Func' does not take 1 arguments

我该如何解决这个问题？我应该如何更改参数？谢谢

Answer 1

这是一个更短的方法，可以满足您的需求:

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;
        }
    }
}

通过添加每个新 Action 作为前一个 Action 的延续，您可以确保一次只处理一个 Action ，因为下一个 Action 要等到上一个 Action 完成后才会开始，您可以确保没有线程闲置无事可做时闲置，并确保它们都按顺序完成。

另请注意，如果您认为只需要一个队列，而不是任何数量，则可以将所有成员设为static，但这取决于您。