PipeStream.ReadAsync Method

Definition

Overloads

ReadAsync(Memory<Byte>, CancellationToken)

Asynchronously reads a sequence of bytes from the current stream, writes them to a byte memory range, advances the position within the stream by the number of bytes read, and monitors cancellation requests.

ReadAsync(Byte[], Int32, Int32, CancellationToken)

Asynchronously reads a sequence of bytes from the current stream to a byte array starting at a specified position for a specified number of bytes, advances the position within the stream by the number of bytes read, and monitors cancellation requests.

ReadAsync(Memory<Byte>, CancellationToken)

Asynchronously reads a sequence of bytes from the current stream, writes them to a byte memory range, advances the position within the stream by the number of bytes read, and monitors cancellation requests.

public override System.Threading.Tasks.ValueTask<int> ReadAsync (Memory<byte> buffer, System.Threading.CancellationToken cancellationToken = null);
override this.ReadAsync : Memory<byte> * System.Threading.CancellationToken -> System.Threading.Tasks.ValueTask<int>

Parameters

buffer
Memory<Byte>

The region of memory to write the data into.

cancellationToken
CancellationToken

The token to monitor for cancellation requests. The default value is None.

Returns

A task that represents the asynchronous read operation. The value of its Result property contains the total number of bytes read into the buffer. The result value can be less than the number of bytes allocated in the buffer if that many bytes are not currently available, or it can be 0 (zero) if the end of the stream has been reached.

Exceptions

The stream does not support reading.

Cannot access a closed pipe.

The pipe hasn't been connected yet.

-or-

The pipe is in a disconnected state.

-or-

The pipe handle has not been set. (Did your PipeStream implementation call InitializeHandle(SafePipeHandle, Boolean, Boolean)?

Remarks

The ReadAsync 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#.

Use the CanRead property to determine whether the current instance supports reading.

If the operation is canceled before it completes, the returned task contains the TaskStatus.Canceled value for the Status property.

ReadAsync(Byte[], Int32, Int32, CancellationToken)

Asynchronously reads a sequence of bytes from the current stream to a byte array starting at a specified position for a specified number of bytes, advances the position within the stream by the number of bytes read, and monitors cancellation requests.

public:
 override System::Threading::Tasks::Task<int> ^ ReadAsync(cli::array <System::Byte> ^ buffer, int offset, int count, System::Threading::CancellationToken cancellationToken);
public override System.Threading.Tasks.Task<int> ReadAsync (byte[] buffer, int offset, int count, System.Threading.CancellationToken cancellationToken);
override this.ReadAsync : byte[] * int * int * System.Threading.CancellationToken -> System.Threading.Tasks.Task<int>

Parameters

buffer
Byte[]

The buffer to write the data into.

offset
Int32

The byte offset in buffer at which to begin writing data from the stream.

count
Int32

The maximum number of bytes to read.

cancellationToken
CancellationToken

The token to monitor for cancellation requests. The default value is None.

Returns

A task that represents the asynchronous read operation. The value of its Result property contains the total number of bytes read into the buffer. The result value can be less than the number of bytes requested if the number of bytes currently available is less than the requested number, or it can be 0 (zero) if the end of the stream has been reached.

Exceptions

The stream does not support reading.

Cannot access a closed pipe.

The pipe hasn't been connected yet.

-or-

The pipe is in a disconnected state.

-or-

The pipe handle has not been set. (Did your PipeStream implementation call InitializeHandle(SafePipeHandle, Boolean, Boolean)?

Remarks

The ReadAsync 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#.

Use the CanRead property to determine whether the current instance supports reading.

If the operation is canceled before it completes, the returned task contains the TaskStatus.Canceled value for the Status property.

Applies to