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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
namespace System.Threading.Tasks.Sources
{
/// <summary>
/// Flags passed from <see cref="ValueTask"/> and <see cref="ValueTask{TResult}"/> to
/// <see cref="IValueTaskSource.OnCompleted"/> and <see cref="IValueTaskSource{TResult}.OnCompleted"/>
/// to control behavior.
/// </summary>
[Flags]
public enum ValueTaskSourceOnCompletedFlags
{
/// <summary>
/// No requirements are placed on how the continuation is invoked.
/// </summary>
None,
/// <summary>
/// Set if OnCompleted should capture the current scheduling context (e.g. SynchronizationContext)
/// and use it when queueing the continuation for execution. If this is not set, the implementation
/// may choose to execute the continuation in an arbitrary location.
/// </summary>
UseSchedulingContext = 0x1,
/// <summary>
/// Set if OnCompleted should capture the current <see cref="ExecutionContext"/> and use it to
/// <see cref="ExecutionContext.Run"/> the continuation.
/// </summary>
FlowExecutionContext = 0x2,
}
/// <summary>Indicates the status of an <see cref="IValueTaskSource"/> or <see cref="IValueTaskSource{TResult}"/>.</summary>
public enum ValueTaskSourceStatus
{
/// <summary>The operation has not yet completed.</summary>
Pending = 0,
/// <summary>The operation completed successfully.</summary>
Succeeded = 1,
/// <summary>The operation completed with an error.</summary>
Faulted = 2,
/// <summary>The operation completed due to cancellation.</summary>
Canceled = 3
}
/// <summary>Represents an object that can be wrapped by a <see cref="ValueTask"/>.</summary>
public interface IValueTaskSource
{
/// <summary>Gets the status of the current operation.</summary>
/// <param name="token">Opaque value that was provided to the <see cref="ValueTask"/>'s constructor.</param>
ValueTaskSourceStatus GetStatus(short token);
/// <summary>Schedules the continuation action for this <see cref="IValueTaskSource"/>.</summary>
/// <param name="continuation">The continuation to invoke when the operation has completed.</param>
/// <param name="state">The state object to pass to <paramref name="continuation"/> when it's invoked.</param>
/// <param name="token">Opaque value that was provided to the <see cref="ValueTask"/>'s constructor.</param>
/// <param name="flags">The flags describing the behavior of the continuation.</param>
void OnCompleted(Action<object> continuation, object state, short token, ValueTaskSourceOnCompletedFlags flags);
/// <summary>Gets the result of the <see cref="IValueTaskSource"/>.</summary>
/// <param name="token">Opaque value that was provided to the <see cref="ValueTask"/>'s constructor.</param>
void GetResult(short token);
}
/// <summary>Represents an object that can be wrapped by a <see cref="ValueTask{TResult}"/>.</summary>
/// <typeparam name="TResult">Specifies the type of data returned from the object.</typeparam>
public interface IValueTaskSource<out TResult>
{
/// <summary>Gets the status of the current operation.</summary>
/// <param name="token">Opaque value that was provided to the <see cref="ValueTask"/>'s constructor.</param>
ValueTaskSourceStatus GetStatus(short token);
/// <summary>Schedules the continuation action for this <see cref="IValueTaskSource{TResult}"/>.</summary>
/// <param name="continuation">The continuation to invoke when the operation has completed.</param>
/// <param name="state">The state object to pass to <paramref name="continuation"/> when it's invoked.</param>
/// <param name="token">Opaque value that was provided to the <see cref="ValueTask"/>'s constructor.</param>
/// <param name="flags">The flags describing the behavior of the continuation.</param>
void OnCompleted(Action<object> continuation, object state, short token, ValueTaskSourceOnCompletedFlags flags);
/// <summary>Gets the result of the <see cref="IValueTaskSource{TResult}"/>.</summary>
/// <param name="token">Opaque value that was provided to the <see cref="ValueTask"/>'s constructor.</param>
TResult GetResult(short token);
}
}
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