private async Task DownloadRangeAsync()
{
Debug.Assert(
this.state == State.Error || this.state == State.Download,
"DownloadRangeAsync called, but state isn't Download or Error");
if (Interlocked.CompareExchange(ref workToken, 0, 1) == 0)
{
return;
}
if (State.Error == this.state)
{
// Some thread has set error message, just return here.
return;
}
if (this.nextDownloadIndex < this.rangeList.Count)
{
Range rangeData = this.rangeList[this.nextDownloadIndex];
int blockSize = this.SharedTransferData.BlockSize;
long blockStartOffset = (rangeData.StartOffset / blockSize) * blockSize;
long nextBlockStartOffset = Math.Min(blockStartOffset + blockSize, this.SharedTransferData.TotalLength);
TransferDownloadStream downloadStream = null;
if ((rangeData.StartOffset > blockStartOffset) && (rangeData.EndOffset < nextBlockStartOffset))
{
Debug.Assert(null != this.currentDownloadBuffer, "Download buffer should have been allocated when range start offset is not block size aligned");
downloadStream = new TransferDownloadStream(this.Scheduler.MemoryManager, this.currentDownloadBuffer, (int)(rangeData.StartOffset - blockStartOffset), (int)(rangeData.EndOffset + 1 - rangeData.StartOffset));
}
else
{
// Attempt to reserve memory. If none available we'll
// retry some time later.
byte[][] memoryBuffer = this.Scheduler.MemoryManager.RequireBuffers(this.SharedTransferData.MemoryChunksRequiredEachTime);
if (null == memoryBuffer)
{
this.SetRangeDownloadHasWork();
return;
}
if (rangeData.EndOffset >= this.lastTransferOffset)
{
bool canRead = true;
lock (this.transferJob.CheckPoint.TransferWindowLock)
{
if (this.transferJob.CheckPoint.TransferWindow.Count >= Constants.MaxCountInTransferWindow)
{
canRead = false;
}
else
{
if (this.transferJob.CheckPoint.EntryTransferOffset < this.SharedTransferData.TotalLength)
{
this.transferJob.CheckPoint.TransferWindow.Add(this.transferJob.CheckPoint.EntryTransferOffset);
this.transferJob.CheckPoint.EntryTransferOffset = Math.Min(this.transferJob.CheckPoint.EntryTransferOffset + blockSize, this.SharedTransferData.TotalLength);
}
}
}
if (!canRead)
{
this.Scheduler.MemoryManager.ReleaseBuffers(memoryBuffer);
this.SetRangeDownloadHasWork();
return;
}
}
if (rangeData.StartOffset == blockStartOffset)
{
this.currentDownloadBuffer = new TransferDownloadBuffer(blockStartOffset, (int)Math.Min(blockSize, this.SharedTransferData.TotalLength - blockStartOffset), memoryBuffer);
downloadStream = new TransferDownloadStream(this.Scheduler.MemoryManager, this.currentDownloadBuffer, 0, (int)(rangeData.EndOffset + 1 - rangeData.StartOffset));
}
else
{
Debug.Assert(null != this.currentDownloadBuffer, "Download buffer should have been allocated when range start offset is not block size aligned");
TransferDownloadBuffer nextBuffer = new TransferDownloadBuffer(nextBlockStartOffset, (int)Math.Min(blockSize, this.SharedTransferData.TotalLength - nextBlockStartOffset), memoryBuffer);
downloadStream = new TransferDownloadStream(
this.Scheduler.MemoryManager,
this.currentDownloadBuffer,
(int)(rangeData.StartOffset - blockStartOffset),
(int)(nextBlockStartOffset - rangeData.StartOffset),
nextBuffer,
0,
(int)(rangeData.EndOffset + 1 - nextBlockStartOffset));
this.currentDownloadBuffer = nextBuffer;
}
}
using (downloadStream)
{
this.nextDownloadIndex++;
this.SetRangeDownloadHasWork();
RangeBasedDownloadState rangeBasedDownloadState = new RangeBasedDownloadState
{
Range = rangeData,
DownloadStream = downloadStream
};
await this.DownloadRangeAsync(rangeBasedDownloadState);
}
this.SetChunkFinish();
return;
}
this.SetRangeDownloadHasWork();
}
private async Task DownloadRangeAsync()
{
Debug.Assert(
this.state == State.Error || this.state == State.Download,
"DownloadRangeAsync called, but state isn't Download or Error");
this.hasWork = false;
if (State.Error == this.state)
{
// Some thread has set error message, just return here.
return;
}
if (this.nextDownloadIndex < this.rangeList.Count)
{
Range rangeData = this.rangeList[this.nextDownloadIndex];
int blockSize = this.Scheduler.TransferOptions.BlockSize;
long blockStartOffset = (rangeData.StartOffset / blockSize) * blockSize;
long nextBlockStartOffset = Math.Min(blockStartOffset + blockSize, this.SharedTransferData.TotalLength);
TransferDownloadStream downloadStream = null;
if ((rangeData.StartOffset > blockStartOffset) && (rangeData.EndOffset < nextBlockStartOffset))
{
Debug.Assert(null != this.currentDownloadBuffer, "Download buffer should have been allocated when range start offset is not block size aligned");
downloadStream = new TransferDownloadStream(this.Scheduler.MemoryManager, this.currentDownloadBuffer, (int)(rangeData.StartOffset - blockStartOffset), (int)(rangeData.EndOffset + 1 - rangeData.StartOffset));
}
else
{
// Attempt to reserve memory. If none available we'll
// retry some time later.
byte[] memoryBuffer = this.Scheduler.MemoryManager.RequireBuffer();
if (null == memoryBuffer)
{
this.SetRangeDownloadHasWork();
return;
}
if (rangeData.EndOffset >= this.lastTransferOffset)
{
bool canRead = true;
lock (this.transferJob.CheckPoint.TransferWindowLock)
{
if (this.transferJob.CheckPoint.TransferWindow.Count >= Constants.MaxCountInTransferWindow)
{
canRead = false;
}
else
{
if (this.transferJob.CheckPoint.EntryTransferOffset < this.SharedTransferData.TotalLength)
{
this.transferJob.CheckPoint.TransferWindow.Add(this.transferJob.CheckPoint.EntryTransferOffset);
this.transferJob.CheckPoint.EntryTransferOffset = Math.Min(this.transferJob.CheckPoint.EntryTransferOffset + this.Scheduler.TransferOptions.BlockSize, this.SharedTransferData.TotalLength);
}
}
}
if (!canRead)
{
this.Scheduler.MemoryManager.ReleaseBuffer(memoryBuffer);
this.SetRangeDownloadHasWork();
return;
}
}
if (rangeData.StartOffset == blockStartOffset)
{
this.currentDownloadBuffer = new TransferDownloadBuffer(blockStartOffset, (int)Math.Min(blockSize, this.SharedTransferData.TotalLength - blockStartOffset), memoryBuffer);
downloadStream = new TransferDownloadStream(this.Scheduler.MemoryManager, this.currentDownloadBuffer, 0, (int)(rangeData.EndOffset + 1 - rangeData.StartOffset));
}
else
{
Debug.Assert(null != this.currentDownloadBuffer, "Download buffer should have been allocated when range start offset is not block size aligned");
TransferDownloadBuffer nextBuffer = new TransferDownloadBuffer(nextBlockStartOffset, (int)Math.Min(blockSize, this.SharedTransferData.TotalLength - nextBlockStartOffset), memoryBuffer);
downloadStream = new TransferDownloadStream(
this.Scheduler.MemoryManager,
this.currentDownloadBuffer,
(int)(rangeData.StartOffset - blockStartOffset),
(int)(nextBlockStartOffset - rangeData.StartOffset),
nextBuffer,
0,
(int)(rangeData.EndOffset + 1 - nextBlockStartOffset));
this.currentDownloadBuffer = nextBuffer;
}
}
using (downloadStream)
{
this.nextDownloadIndex++;
this.SetRangeDownloadHasWork();
RangeBasedDownloadState rangeBasedDownloadState = new RangeBasedDownloadState
{
Range = rangeData,
DownloadStream = downloadStream
};
await this.DownloadRangeAsync(rangeBasedDownloadState);
}
this.SetChunkFinish();
return;
}
this.SetRangeDownloadHasWork();
}
