public async Task ParallelDownloadSlowTest()
{
string inputFileName = Path.GetTempFileName();
string outputFileName = Path.GetTempFileName();
CloudBlobContainer container = GetRandomContainerReference();
try
{
await container.CreateAsync();
CloudBlockBlob blob = container.GetBlockBlobReference("largeblob1");
long bufferSize = 12 * Constants.KB;
long offSet = 0;
using (FileStream file = new FileStream(inputFileName, FileMode.Create, FileAccess.Write))
{
while (offSet < 12 * Constants.MB)
{
byte[] buffer = GetRandomBuffer(bufferSize);
await file.WriteAsync(buffer, 0, buffer.Length);
offSet += bufferSize;
}
}
BlobRequestOptions options = new BlobRequestOptions();
options.ParallelOperationThreadCount = 16;
await blob.UploadFromFileAsync(inputFileName, null, options, null);
int parallelIOCount = 2;
long rangeSizeInBytes = 4 * Constants.MB;
CancellationTokenSource cancellationTokenSource = new CancellationTokenSource();
DelayingDownloadRangeCloudBlob wrapperBlob = new DelayingDownloadRangeCloudBlob(blob.SnapshotQualifiedUri, blob.ServiceClient, 1000, 1000000);
await ParallelDownloadToFile.Start(wrapperBlob, outputFileName,
FileMode.Create,
parallelIOCount,
rangeSizeInBytes,
0,
null,
10000 /* Amount of time to wait before abort / retry */,
null,
null,
null,
CancellationToken.None).Task;
await blob.DeleteAsync();
Assert.IsTrue(FilesAreEqual(inputFileName, outputFileName));
}
finally
{
container.DeleteIfExists();
File.Delete(inputFileName);
File.Delete(outputFileName);
}
}
/// <summary>
/// Starts the download of a blob to a file.
/// </summary>
/// <param name="blob">The <see cref="CloudBlob"/> to download.</param>
/// <param name="filePath">A string containing the path to the target file.</param>
/// <param name="fileMode">A <see cref="System.IO.FileMode"/> enumeration value that determines how to open or create the file.</param>
/// <param name="parallelIOCount">The maximum number of ranges that can be downloaded concurrently</param>
/// <param name="rangeSizeInBytes">The size of each individual range in bytes that is being dowloaded in parallel.
/// The range size must be a multiple of 4 KB and a minimum of 4 MB with a default value of 16 MB.</param>
/// <param name="offset">The offset of the blob.</param>
/// <param name="length">The number of bytes to download.</param>
/// <param name="accessCondition">An <see cref="AccessCondition"/> object that represents the condition that must be met in order for the request to proceed.</param>
/// <param name="options">A <see cref="BlobRequestOptions"/> object that specifies additional options for the request.</param>
/// <param name="operationContext">An <see cref="OperationContext"/> object that represents the context for the current operation.</param>
/// <param name="cancellationToken">A <see cref="CancellationToken"/> to observe while waiting for a task to complete.</param>
/// <returns>A <see cref="ParallelDownloadToFile"/> object which contains a task that can be awaited for completion.</returns>
public static ParallelDownloadToFile Start(CloudBlob blob, string filePath, FileMode fileMode, int parallelIOCount, long?rangeSizeInBytes, long offset, long?length, AccessCondition accessCondition, BlobRequestOptions options, OperationContext operationContext, CancellationToken cancellationToken)
{
ParallelDownloadToFile parallelDownload = new ParallelDownloadToFile(blob, filePath, offset, length, cancellationToken);
parallelDownload.operationContext = operationContext;
parallelDownload.blobRequestOptions = options;
parallelDownload.accessCondition = accessCondition;
parallelDownload.Task = parallelDownload.StartAsync(fileMode, parallelIOCount, rangeSizeInBytes);
return(parallelDownload);
}