PipeStream.ReadAsync Method

Definition

Namespace:

System.IO.Pipes

Assembly:

System.IO.Pipes.dll

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)

Source:

PipeStream.Unix.cs

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 = default);

override this.ReadAsync : Memory<byte> * System.Threading.CancellationToken -> System.Threading.Tasks.ValueTask<int>

Public Overrides Function ReadAsync (buffer As Memory(Of Byte), Optional cancellationToken As CancellationToken = Nothing) As ValueTask(Of Integer)

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

ValueTask<Int32>

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

NotSupportedException

The stream does not support reading.

ObjectDisposedException

Cannot access a closed pipe.

InvalidOperationException

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)?

OperationCanceledException

The cancellation token was canceled. This exception is stored into the returned task.

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 applications 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)

Source:

PipeStream.Unix.cs

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>

Public Overrides Function ReadAsync (buffer As Byte(), offset As Integer, count As Integer, cancellationToken As CancellationToken) As Task(Of Integer)

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

Task<Int32>

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

NotSupportedException

The stream does not support reading.

ObjectDisposedException

Cannot access a closed pipe.

InvalidOperationException

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)?

OperationCanceledException

The cancellation token was canceled. This exception is stored into the returned task.

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 applications 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.

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 Read(Byte[], Int32, Int32).