CODEWITHSUNDEEP
c#queue
Muhammad Faizan Khan
Muhammad Faizan Khan

Reputation: 10551

Perform operation before dequeue in C#

There are several download requests which i want to serve one by one and for this reason i am using Queue. Here is the list, which is populating from different scripts at different times

 public Queue<WebDownloader> webDownloaderQ;

A public method allow to different scripts/resource to populate the queue dynamically at different times:

 public void EnqueABDownloading(WebDownloader abToDownload)
    {
        singleAbLoader.Enqueue(abToDownload);
    }

The download starts quickly as it found even a single que object, (Remember during this time queue can be incremented),

     public void StartDownloading()
        {
            //while (singleAbLoader.Count > 0)
            //{
            //    singleAbLoader.

            //}

            for (int i = 0; i < singleAbLoader.Count; i++)
            {
                singleAbLoader[i].//this is not supporting unable to call my method
//I want to call one of the function (startdowloaind) of WebDownloader before the deque 
            }
        }

I tried to write above function for downloading but the problem is, i dont know how to do this. I tried to used index with the object it saying cannot apply indexing with to an expression of type Queue.

EDIT:

Remember: I want to call one of the function (StartDowloaind) of WebDownloader before the Dequeue the object.

I want to first enqueue the request, the reason is that every request will take sometime to download. Therefore,

  1. first enqueue the download request

  2. then, check download loop is running or not if not then, initiate the loop

  3. As specific download complete dequeue the request.

Upvotes: 1

Views: 251

Answers (2)

Mahmoud-Abdelslam
Mahmoud-Abdelslam

Reputation: 643

please use Dequeue Method to pop up the item like the following 

while (singleAbLoader.Count>0)
(
WebDownloader method= singleAbLoader.Dequeue();
 method.StartDowloaind();

}

by this way even if the queue is incremented it will continue to use pop up and without the need for the index .

I also suggest to use ConcurrentQueue if the queue will be used by multiple threads

Upvotes: 0

Ashkan Mobayen Khiabani
Ashkan Mobayen Khiabani

Reputation: 34150

You can use foreach to loop through your queue. foreach does not Dequeue

 public void StartDownloading()
 {
        foreach(WebDownloader wd in singleAbLoader)
        {
             wd.Start();
        }
 }

Considering your comment:

As downloads may not complete in the order they start, so use a List instead of Queue.

Your class WebDownloader obviously has something like DownloadCompleted event, you can remove it from the list in there. or if you need it, just then add it to a queue of completed downloads.

Upvotes: 1

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