public DownloadTask(Downloader downloader, Uri url, Action<DownloadResult> callback, DownloadOptions options, string key, DownloadResult result)
{
this.downloader = downloader;
this.Url = url;
this.Callback = callback;
this.Options = options;
this.Key = key;
this.Result = result;
}
/// <summary>
/// Cancels a pending or in-progress download operation.
/// </summary>
/// <param name="result">The <see cref="DownloadResult"/> representing the operation to cancel.</param>
/// <returns>True if the operation was found and cancelled, false otherwise.</returns>
public bool Cancel(DownloadResult result)
{
if (this.disposed)
{
throw new ObjectDisposedException(this.GetType().Name);
}
if (result == null)
{
throw new ArgumentNullException("result", "result cannot be null.");
}
bool cancelled = false;
DownloadTask task = null;
lock (this.syncRoot)
{
task = this.processing.Where(t => t.Result == result).FirstOrDefault();
if (task == null)
{
task = this.queued.Where(t => t.Result == result).FirstOrDefault();
if (task != null)
{
this.queued.Remove(task);
}
}
if (task != null)
{
task.Abort();
cancelled = true;
}
}
return cancelled;
}
/// <summary>
/// Initiates a cached + queued download operation.
/// </summary>
/// <param name="url">The URL of the resource to download.</param>
/// <param name="callback">A function to call when the operation is complete.</param>
/// <param name="options">The options to use when downloading the resource.</param>
/// <returns>The operation's result.</returns>
public DownloadResult Download(Uri url, Action<DownloadResult> callback, DownloadOptions options)
{
if (this.disposed)
{
throw new ObjectDisposedException(this.GetType().Name);
}
if (url == null)
{
throw new ArgumentNullException("url", "url cannot be null.");
}
DownloadResult result;
string key = url.ToString().ToUpperInvariant();
byte[] content = this.cache.GetContent(key);
if (content != null)
{
result = new DownloadResult(content, true);
}
else
{
result = new DownloadResult();
options = new DownloadOptions(options);
this.Enqueue(new DownloadTask(this, url, callback, options, key, result));
}
return result;
}
