/// <summary>
/// <see cref="IDevice.WriteAsync(IntPtr, int, ulong, uint, DeviceIOCompletionCallback, object)">Inherited</see>
/// </summary>
public override void WriteAsync(IntPtr sourceAddress, int segmentId, ulong destinationAddress, uint numBytesToWrite, DeviceIOCompletionCallback callback, object context)
{
Debug.WriteLine($"AzureStorageDevice.WriteAsync Called segmentId={segmentId} destinationAddress={destinationAddress} numBytesToWrite={numBytesToWrite}");
if (!blobs.TryGetValue(segmentId, out BlobEntry blobEntry))
{
BlobEntry entry = new BlobEntry(this.BlobManager);
if (blobs.TryAdd(segmentId, entry))
{
CloudPageBlob pageBlob = this.blobDirectory.GetPageBlobReference(GetSegmentBlobName(segmentId));
// If segment size is -1, which denotes absence, we request the largest possible blob. This is okay because
// page blobs are not backed by real pages on creation, and the given size is only a the physical limit of
// how large it can grow to.
var size = segmentSize == -1 ? MAX_BLOB_SIZE : segmentSize;
// If no blob exists for the segment, we must first create the segment asynchronouly. (Create call takes ~70 ms by measurement)
// After creation is done, we can call write.
var _ = entry.CreateAsync(size, pageBlob);
}
// Otherwise, some other thread beat us to it. Okay to use their blobs.
blobEntry = blobs[segmentId];
}
this.TryWriteAsync(blobEntry, sourceAddress, destinationAddress, numBytesToWrite, callback, context);
}
private void TryWriteAsync(BlobEntry blobEntry, IntPtr sourceAddress, ulong destinationAddress, uint numBytesToWrite, DeviceIOCompletionCallback callback, object context)
{
// If pageBlob is null, it is being created. Attempt to queue the write for the creator to complete after it is done
if (blobEntry.PageBlob == null &&
blobEntry.TryQueueAction(p => this.WriteToBlobAsync(p, sourceAddress, destinationAddress, numBytesToWrite, callback, context)))
{
return;
}
// Otherwise, invoke directly.
this.WriteToBlobAsync(blobEntry.PageBlob, sourceAddress, destinationAddress, numBytesToWrite, callback, context);
}
private void TryWriteAsync(BlobEntry blobEntry, IntPtr sourceAddress, ulong destinationAddress, uint numBytesToWrite, IOCompletionCallback callback, IAsyncResult asyncResult)
{
CloudPageBlob pageBlob = blobEntry.GetPageBlob();
// If pageBlob is null, it is being created. Attempt to queue the write for the creator to complete after it is done
if (pageBlob == null &&
blobEntry.TryQueueAction(p => WriteToBlobAsync(p, sourceAddress, destinationAddress, numBytesToWrite, callback, asyncResult)))
{
return;
}
// Otherwise, invoke directly.
WriteToBlobAsync(pageBlob, sourceAddress, destinationAddress, numBytesToWrite, callback, asyncResult);
}
/// <summary>
/// <see cref="IDevice.WriteAsync(IntPtr, int, ulong, uint, IOCompletionCallback, IAsyncResult)">Inherited</see>
/// </summary>
public override void WriteAsync(IntPtr sourceAddress, int segmentId, ulong destinationAddress, uint numBytesToWrite, IOCompletionCallback callback, IAsyncResult asyncResult)
{
if (!blobs.TryGetValue(segmentId, out BlobEntry blobEntry))
{
BlobEntry entry = new BlobEntry();
if (blobs.TryAdd(segmentId, entry))
{
CloudPageBlob pageBlob = container.GetPageBlobReference(blobName + segmentId);
// If segment size is -1, which denotes absence, we request the largest possible blob. This is okay because
// page blobs are not backed by real pages on creation, and the given size is only a the physical limit of
// how large it can grow to.
var size = segmentSize == -1 ? MAX_BLOB_SIZE : segmentSize;
// If no blob exists for the segment, we must first create the segment asynchronouly. (Create call takes ~70 ms by measurement)
// After creation is done, we can call write.
entry.CreateAsync(size, pageBlob);
}
// Otherwise, some other thread beat us to it. Okay to use their blobs.
blobEntry = blobs[segmentId];
}
TryWriteAsync(blobEntry, sourceAddress, destinationAddress, numBytesToWrite, callback, asyncResult);
}
