/// <summary>
/// cancel a background task - or prevent a task from running
/// </summary>
public void Cancel()
{
lock (_lock)
{
if (_client != null)
{
_client.CancelAsync();
}
else
{
// probably an unstarted task or a task that has completed
_complete = true;
TaskComplete.Set();
}
}
}
public static void DownloadFileSync(this IWebClient client, Uri address, string filename, CancellationToken cancellationToken)
{
// Events are only fired when downloading asynchronously with DownloadFileAsync.
// This method allows for synchronous downloads while still firing events.
// Based on the solution given here: https://stackoverflow.com/a/25834736 (user195275)
object mutex = new object();
bool downloadCancelled = false;
void handleDownloadComplete(object sender, AsyncCompletedEventArgs e)
{
downloadCancelled = e.Cancelled;
lock (e.UserState)
Monitor.Pulse(e.UserState);
}
client.DownloadFileCompleted += handleDownloadComplete;
try {
lock (mutex) {
using (cancellationToken.Register(() => client.CancelAsync())) {
client.DownloadFileAsync(address, filename, mutex);
Monitor.Wait(mutex);
}
}
}
finally {
client.DownloadFileCompleted -= handleDownloadComplete;
}
if (downloadCancelled)
{
throw new WebException(Properties.ExceptionMessages.TheRequestWasCancelled, WebExceptionStatus.RequestCanceled);
}
}
static Timer SetupTransferProgress(IWebClient webClient, ITransferProgress transferProgress) {
var lastTime = Tools.Generic.GetCurrentUtcDateTime;
long lastBytes = 0;
transferProgress.Progress = 0;
transferProgress.FileSizeTransfered = 0;
webClient.DownloadProgressChanged +=
(sender, args) => {
var bytes = args.BytesReceived;
var now = Tools.Generic.GetCurrentUtcDateTime;
transferProgress.Progress = args.ProgressPercentage;
transferProgress.FileSizeTransfered = bytes;
if (lastBytes != 0) {
var timeSpan = now - lastTime;
var bytesChange = bytes - lastBytes;
if (timeSpan.TotalMilliseconds > 0)
transferProgress.Speed = (long) (bytesChange/(timeSpan.TotalMilliseconds/1000.0));
}
lastBytes = bytes;
lastTime = now;
};
webClient.DownloadFileCompleted += (sender, args) => { transferProgress.Completed = true; };
var timer = new TimerWithElapsedCancellation(500, () => {
if (!transferProgress.Completed
&& Tools.Generic.LongerAgoThan(lastTime, timeout)) {
webClient.CancelAsync();
return false;
}
return !transferProgress.Completed;
});
return timer;
}
