BufferedStream.CopyToAsync(Stream, Int32, CancellationToken) Method
Definition
Important
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Asynchronously reads the bytes from the current buffered stream and writes them to another stream, using a specified buffer size and cancellation token.
public:
override System::Threading::Tasks::Task ^ CopyToAsync(System::IO::Stream ^ destination, int bufferSize, System::Threading::CancellationToken cancellationToken);public override System.Threading.Tasks.Task CopyToAsync (System.IO.Stream destination, int bufferSize, System.Threading.CancellationToken cancellationToken);override this.CopyToAsync : System.IO.Stream * int * System.Threading.CancellationToken -> System.Threading.Tasks.TaskPublic Overrides Function CopyToAsync (destination As Stream, bufferSize As Integer, cancellationToken As CancellationToken) As TaskParameters
- destination
- Stream
The stream to which the contents of the current buffered stream will be copied.
- bufferSize
- Int32
The size, in bytes, of the buffer. This value must be greater than zero. The default sizer is 81920.
- cancellationToken
- CancellationToken
The token to monitor for cancellation requests. The default value is None.
Returns
A task that represents the asynchronous copy operation.
Exceptions
The cancellation token was canceled. This exception is stored into the returned task.
Remarks
The CopyToAsync method enables you to perform resource-intensive I/O operations without blocking the main thread. This performance consideration is particularly important in a Windows 8.x Store app or desktop app where a time-consuming stream operation can block the UI thread and make your app appear as if it is not working. The async methods are used in conjunction with the async and await keywords in Visual Basic and C#.
If the operation is canceled before it completes, the returned task contains the Canceled value for the Status property.
Copying begins at the current position in the current stream.
This method stores in the task it returns all non-usage exceptions that the method's synchronous counterpart can throw. If an exception is stored into the returned task, that exception will be thrown when the task is awaited. Usage exceptions, such as ArgumentException, are still thrown synchronously. For the stored exceptions, see the exceptions thrown by CopyTo(Stream, Int32).
