private static DownloadTask SafeDequeue(Queue <DownloadTask> queues)
{
DownloadTask downloadTask = null;
lock (queues)
{
try
{
downloadTask = queues.Dequeue();
}
catch (Exception ex)
{
//ignore
}
}
return(downloadTask);
}
private static Task StartNextTask(Queue <DownloadTask> queues)
{
if (queues.Count <= 0)
{
return(null);
}
return(Task.Run(async() =>
{
DownloadTask downloadTask = SafeDequeue(queues);
if (downloadTask != null)
{
await downloadTask.StartAsync();
}
while (queues.Count > 0)
{
DownloadTask nextTask = SafeDequeue(queues);
if (nextTask != null)
{
await nextTask.StartAsync();
}
}
}));
}
public static DownloadTask DownloadAsync(this DownloadSegmentInfo downloadInfo,
Action <long, float> progressAction, CancellationToken cancellationToken = default)
{
Pipe pipeline = new Pipe();
bool isCompleted = false;
var downloadTask = new DownloadTask(downloadInfo);
Func <List <Task> > func = new Func <List <Task> >(() =>
{
var readTask = Task.Run(async() =>
{
int bytesRead;
try
{
if (downloadInfo.Percentage >= 100)
{
return;
}
if (downloadInfo.Size != 0 && downloadInfo.TotalReadBytes == downloadInfo.Size)
{
return;
}
if (downloadInfo.SrcStream == null)
{
var httpClient = HttpClientFactory.Instance.GetHttpClient(downloadInfo.Url);
if (downloadInfo.Size != 0)
{
httpClient.DefaultRequestHeaders.Range = new RangeHeaderValue(downloadInfo.TotalReadBytes, downloadInfo.Size);
}
var response = await httpClient.GetAsync(downloadInfo.Url);
downloadInfo.SrcStream = await response.Content.ReadAsStreamAsync();
var size = response.Content.Headers.ContentLength.GetValueOrDefault();
if (size > 0 && downloadInfo.Size == 0)
{
downloadInfo.Size = size;
if (downloadInfo.End == 0)
{
downloadInfo.End = downloadInfo.Start + size;
}
}
if (downloadInfo.TotalReadBytes > 0)
{
///设置文件流写入位置
downloadInfo.DstStream.Position = downloadInfo.Start + downloadInfo.TotalReadBytes;
}
}
while (true) // Where the downloading part is happening
{
bytesRead = await downloadInfo.SrcStream.ReadAsync(pipeline.Writer.GetMemory(), cancellationToken);
if (bytesRead <= 0)
{
break;
}
pipeline.Writer.Advance(bytesRead);
var flushResult = await pipeline.Writer.FlushAsync(cancellationToken);
if (flushResult.IsCanceled)
{
break;
}
if (flushResult.IsCompleted)
{
break;
}
}
pipeline.Writer.Complete();
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
finally
{
isCompleted = true;
}
}, cancellationToken);
var writeTask = Task.Run(async() =>
{
float percentage = 0;
long bytesRead = 0;
try
{
while (true)
{
var readResult = await pipeline.Reader.ReadAsync(cancellationToken);
foreach (var segment in readResult.Buffer)
{
bytesRead += segment.Length;
await downloadInfo.DstStream.WriteAsync(segment, cancellationToken);
}
downloadInfo.TotalReadBytes += bytesRead;
if (bytesRead > 0)//有进度才会提示
{
percentage = downloadInfo.Percentage;
progressAction.Invoke(bytesRead, percentage); // To Get the current percentage.
bytesRead = 0;
}
pipeline.Reader.AdvanceTo(readResult.Buffer.End);
if (readResult.IsCompleted || readResult.IsCanceled)
{
break;
}
if (isCompleted)
{
break;
}
}
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
finally
{
isCompleted = true;
downloadTask.Close();
}
pipeline.Reader.Complete();
}, cancellationToken);
return(new List <Task>()
{
readTask, writeTask
});
});
downloadTask.Create(func);
return(downloadTask);
}
