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// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved. See License.txt in the project root for license information.
#if !WINDOWS
using System.Reactive.Disposables;
using System.Threading;
namespace System.Reactive.Concurrency
{
/// <summary>
/// Represents an object that schedules units of work on a <see cref="System.Windows.Threading.Dispatcher"/>.
/// </summary>
/// <remarks>
/// This scheduler type is typically used indirectly through the <see cref="System.Reactive.Linq.DispatcherObservable.ObserveOnDispatcher<TSource>(IObservable<TSource>)"/> and <see cref="System.Reactive.Linq.DispatcherObservable.SubscribeOnDispatcher<TSource>(IObservable<TSource>)"/> methods that use the Dispatcher on the calling thread.
/// </remarks>
public class DispatcherScheduler : LocalScheduler, ISchedulerPeriodic
{
/// <summary>
/// Gets the scheduler that schedules work on the current <see cref="System.Windows.Threading.Dispatcher"/>.
/// </summary>
[Obsolete(Constants_WindowsThreading.OBSOLETE_INSTANCE_PROPERTY)]
public static DispatcherScheduler Instance
{
get
{
return new DispatcherScheduler(
#if USE_SL_DISPATCHER
System.Windows.Deployment.Current.Dispatcher
#else
System.Windows.Threading.Dispatcher.CurrentDispatcher
#endif
);
}
}
/// <summary>
/// Gets the scheduler that schedules work on the <see cref="System.Windows.Threading.Dispatcher"/> for the current thread.
/// </summary>
public static DispatcherScheduler Current
{
get
{
#if USE_SL_DISPATCHER
return new DispatcherScheduler(System.Windows.Deployment.Current.Dispatcher);
#else
var dispatcher = System.Windows.Threading.Dispatcher.FromThread(Thread.CurrentThread);
if (dispatcher == null)
throw new InvalidOperationException(Strings_WindowsThreading.NO_DISPATCHER_CURRENT_THREAD);
return new DispatcherScheduler(dispatcher);
#endif
}
}
System.Windows.Threading.Dispatcher _dispatcher;
#if HAS_DISPATCHER_PRIORITY
System.Windows.Threading.DispatcherPriority _priority;
#endif
/// <summary>
/// Constructs a DispatcherScheduler that schedules units of work on the given <see cref="System.Windows.Threading.Dispatcher"/>.
/// </summary>
/// <param name="dispatcher">Dispatcher to schedule work on.</param>
/// <exception cref="ArgumentNullException"><paramref name="dispatcher"/> is null.</exception>
public DispatcherScheduler(System.Windows.Threading.Dispatcher dispatcher)
{
if (dispatcher == null)
throw new ArgumentNullException("dispatcher");
_dispatcher = dispatcher;
#if HAS_DISPATCHER_PRIORITY
_priority = Windows.Threading.DispatcherPriority.Normal;
#endif
}
#if HAS_DISPATCHER_PRIORITY
/// <summary>
/// Constructs a DispatcherScheduler that schedules units of work on the given <see cref="System.Windows.Threading.Dispatcher"/> at the given priority.
/// </summary>
/// <param name="dispatcher">Dispatcher to schedule work on.</param>
/// <param name="priority">Priority at which units of work are scheduled.</param>
/// <exception cref="ArgumentNullException"><paramref name="dispatcher"/> is null.</exception>
public DispatcherScheduler(System.Windows.Threading.Dispatcher dispatcher, System.Windows.Threading.DispatcherPriority priority)
{
if (dispatcher == null)
throw new ArgumentNullException("dispatcher");
_dispatcher = dispatcher;
_priority = priority;
}
#endif
/// <summary>
/// Gets the <see cref="System.Windows.Threading.Dispatcher"/> associated with the DispatcherScheduler.
/// </summary>
public System.Windows.Threading.Dispatcher Dispatcher
{
get { return _dispatcher; }
}
#if HAS_DISPATCHER_PRIORITY
/// <summary>
/// Gets the priority at which work items will be dispatched.
/// </summary>
public System.Windows.Threading.DispatcherPriority Priority
{
get { return _priority; }
}
#endif
/// <summary>
/// Schedules an action to be executed on the dispatcher.
/// </summary>
/// <typeparam name="TState">The type of the state passed to the scheduled action.</typeparam>
/// <param name="state">State passed to the action to be executed.</param>
/// <param name="action">Action to be executed.</param>
/// <returns>The disposable object used to cancel the scheduled action (best effort).</returns>
/// <exception cref="ArgumentNullException"><paramref name="action"/> is null.</exception>
public override IDisposable Schedule<TState>(TState state, Func<IScheduler, TState, IDisposable> action)
{
if (action == null)
throw new ArgumentNullException("action");
var d = new SingleAssignmentDisposable();
_dispatcher.BeginInvoke(
new Action(() =>
{
if (!d.IsDisposed)
d.Disposable = action(this, state);
})
#if HAS_DISPATCHER_PRIORITY
, _priority
#endif
);
return d;
}
/// <summary>
/// Schedules an action to be executed after dueTime on the dispatcher, using a <see cref="System.Windows.Threading.DispatcherTimer"/> object.
/// </summary>
/// <typeparam name="TState">The type of the state passed to the scheduled action.</typeparam>
/// <param name="state">State passed to the action to be executed.</param>
/// <param name="action">Action to be executed.</param>
/// <param name="dueTime">Relative time after which to execute the action.</param>
/// <returns>The disposable object used to cancel the scheduled action (best effort).</returns>
/// <exception cref="ArgumentNullException"><paramref name="action"/> is null.</exception>
public override IDisposable Schedule<TState>(TState state, TimeSpan dueTime, Func<IScheduler, TState, IDisposable> action)
{
if (action == null)
throw new ArgumentNullException("action");
var dt = Scheduler.Normalize(dueTime);
if (dt.Ticks == 0)
return Schedule(state, action);
var d = new MultipleAssignmentDisposable();
var timer = new System.Windows.Threading.DispatcherTimer(
#if HAS_DISPATCHER_PRIORITY
_priority, _dispatcher
#elif DESKTOPCLR40 // BACKWARDS COMPATIBILITY with v1.x
System.Windows.Threading.DispatcherPriority.Background, _dispatcher
#endif
);
timer.Tick += (s, e) =>
{
var t = Interlocked.Exchange(ref timer, null);
if (t != null)
{
try
{
d.Disposable = action(this, state);
}
finally
{
t.Stop();
action = null;
}
}
};
timer.Interval = dt;
timer.Start();
d.Disposable = Disposable.Create(() =>
{
var t = Interlocked.Exchange(ref timer, null);
if (t != null)
{
t.Stop();
action = (_, __) => Disposable.Empty;
}
});
return d;
}
/// <summary>
/// Schedules a periodic piece of work on the dispatcher, using a <see cref="System.Windows.Threading.DispatcherTimer"/> object.
/// </summary>
/// <typeparam name="TState">The type of the state passed to the scheduled action.</typeparam>
/// <param name="state">Initial state passed to the action upon the first iteration.</param>
/// <param name="period">Period for running the work periodically.</param>
/// <param name="action">Action to be executed, potentially updating the state.</param>
/// <returns>The disposable object used to cancel the scheduled recurring action (best effort).</returns>
/// <exception cref="ArgumentNullException"><paramref name="action"/> is null.</exception>
/// <exception cref="ArgumentOutOfRangeException"><paramref name="period"/> is less than TimeSpan.Zero.</exception>
public IDisposable SchedulePeriodic<TState>(TState state, TimeSpan period, Func<TState, TState> action)
{
if (period < TimeSpan.Zero)
throw new ArgumentOutOfRangeException("period");
if (action == null)
throw new ArgumentNullException("action");
var timer = new System.Windows.Threading.DispatcherTimer(
#if HAS_DISPATCHER_PRIORITY
_priority, _dispatcher
#elif DESKTOPCLR40 // BACKWARDS COMPATIBILITY with v1.x
System.Windows.Threading.DispatcherPriority.Background, _dispatcher
#endif
);
var state1 = state;
timer.Tick += (s, e) =>
{
state1 = action(state1);
};
timer.Interval = period;
timer.Start();
return Disposable.Create(() =>
{
var t = Interlocked.Exchange(ref timer, null);
if (t != null)
{
t.Stop();
action = _ => _;
}
});
}
}
}
#endif
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