101 lines
4.5 KiB
C#
101 lines
4.5 KiB
C#
// Licensed to the .NET Foundation under one or more agreements.
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// The .NET Foundation licenses this file to you under the MIT License.
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// See the LICENSE file in the project root for more information.
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using System.Reactive.Disposables;
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using System.Threading;
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namespace System.Reactive.Concurrency
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{
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/// <summary>
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/// Represents an object that schedules units of work on a provided <seealso cref="SynchronizationContext"/>.
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/// </summary>
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public class SynchronizationContextScheduler : LocalScheduler
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{
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private readonly SynchronizationContext _context;
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private readonly bool _alwaysPost;
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/// <summary>
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/// Creates an object that schedules units of work on the provided <see cref="SynchronizationContext"/>.
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/// </summary>
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/// <param name="context">Synchronization context to schedule units of work on.</param>
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/// <exception cref="ArgumentNullException"><paramref name="context"/> is <c>null</c>.</exception>
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public SynchronizationContextScheduler(SynchronizationContext context)
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{
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_context = context ?? throw new ArgumentNullException(nameof(context));
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_alwaysPost = true;
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}
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/// <summary>
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/// Creates an object that schedules units of work on the provided <see cref="SynchronizationContext"/>.
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/// </summary>
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/// <param name="context">Synchronization context to schedule units of work on.</param>
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/// <param name="alwaysPost">Configures whether scheduling always posts to the synchronization context, regardless whether the caller is on the same synchronization context.</param>
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/// <exception cref="ArgumentNullException"><paramref name="context"/> is <c>null</c>.</exception>
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public SynchronizationContextScheduler(SynchronizationContext context, bool alwaysPost)
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{
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_context = context ?? throw new ArgumentNullException(nameof(context));
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_alwaysPost = alwaysPost;
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}
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/// <summary>
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/// Schedules an action to be executed.
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/// </summary>
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/// <typeparam name="TState">The type of the state passed to the scheduled action.</typeparam>
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/// <param name="state">State passed to the action to be executed.</param>
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/// <param name="action">Action to be executed.</param>
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/// <returns>The disposable object used to cancel the scheduled action (best effort).</returns>
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/// <exception cref="ArgumentNullException"><paramref name="action"/> is <c>null</c>.</exception>
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public override IDisposable Schedule<TState>(TState state, Func<IScheduler, TState, IDisposable> action)
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{
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if (action == null)
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{
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throw new ArgumentNullException(nameof(action));
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}
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if (!_alwaysPost && _context == SynchronizationContext.Current)
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{
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return action(this, state);
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}
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var d = new SingleAssignmentDisposable();
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_context.PostWithStartComplete(() =>
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{
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if (!d.IsDisposed)
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{
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d.Disposable = action(this, state);
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}
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});
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return d;
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}
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/// <summary>
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/// Schedules an action to be executed after dueTime.
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/// </summary>
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/// <typeparam name="TState">The type of the state passed to the scheduled action.</typeparam>
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/// <param name="state">State passed to the action to be executed.</param>
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/// <param name="action">Action to be executed.</param>
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/// <param name="dueTime">Relative time after which to execute the action.</param>
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/// <returns>The disposable object used to cancel the scheduled action (best effort).</returns>
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/// <exception cref="ArgumentNullException"><paramref name="action"/> is <c>null</c>.</exception>
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public override IDisposable Schedule<TState>(TState state, TimeSpan dueTime, Func<IScheduler, TState, IDisposable> action)
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{
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if (action == null)
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{
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throw new ArgumentNullException(nameof(action));
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}
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var dt = Scheduler.Normalize(dueTime);
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if (dt.Ticks == 0)
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{
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return Schedule(state, action);
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}
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// Note that avoiding closure allocation here would introduce infinite generic recursion over the TState argument
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return DefaultScheduler.Instance.Schedule(state, dt, (_, state1) => Schedule(state1, action));
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}
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}
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}
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