/// <summary>
/// creates a new download job
/// </summary>
/// <param name="dwnlSource">url to download from</param>
/// <param name="dwnlTarget">url to download to</param>
public Download(string dwnlSource, string dwnlTarget)
{
//set the download data
DwnlSource = dwnlSource;
DwnlTarget = dwnlTarget;
DwnlSize = FindFileSize(DwnlSource);
//create the virtual chunk download jobs and its scheduler
DwnlChunks = new Chunks(DwnlSource, DwnlSize);
DwnlScheduler = new DownloadScheduler(DwnlChunks);
}
/// <summary>
/// updates the download progress
/// </summary>
/// <param name="timeSpan">time span of update</param>
public void UpdateDownloadProgress(double timeSpan)
{
//initial download progress parameters
double bufferedSize;
double downloadedSize = DwnlChunks.ChunkSize * windowStart;
Chunks chunks = DwnlChunks;
//adjust the start of the window if completed
while (windowStart < chunks.ChunkCount)
{
bufferedSize = Interlocked.Read(ref chunks.ChunkProgress[windowStart]);
if (bufferedSize == chunks.ChunkSize)
{
windowStart++;
downloadedSize += chunks.ChunkSize;
}
else
{
break;
}
}
//update the size of the active chunks
for (long i = windowStart; i < chunks.ChunkCount; i++)
{
bufferedSize = Interlocked.Read(ref DwnlChunks.ChunkProgress[i]);
if (bufferedSize != 0)
{
downloadedSize += bufferedSize;
}
else
{
break;
}
}
//compute the speed and progress
DwnlSpeed = Math.Max(0, downloadedSize - DwnlSizeCompleted) / timeSpan;
DwnlSizeCompleted = downloadedSize;
DwnlProgress = DwnlSizeCompleted / DwnlSize * 100;
}
/// <summary>
/// initialize the download scheduler
/// </summary>
/// <param name="chunks">the chunk download jobs</param>
public DownloadScheduler(Chunks chunks)
{
Chunks = chunks;
}