Class Scheduler

Provides a set of static properties to access commonly used schedulers.

Inheritance

Object

Scheduler

Inherited Members

Object.Equals(Object)

Object.Equals(Object, Object)

Object.GetHashCode()

Object.GetType()

Object.MemberwiseClone()

Object.ToString()

Object.ReferenceEquals(Object, Object)

Namespace: System.Reactive.Concurrency

Assembly: System.Reactive.Core.dll

Syntax

public static class Scheduler

Properties

CurrentThread

Gets a scheduler that schedules work as soon as possible on the current thread.

Declaration

public static CurrentThreadScheduler CurrentThread { get; }

Property Value

Type	Description
CurrentThreadScheduler

Default

Gets a scheduler that schedules work on the platform's default scheduler.

Declaration

public static DefaultScheduler Default { get; }

Property Value

Type	Description
DefaultScheduler

Immediate

Gets a scheduler that schedules work immediately on the current thread.

Declaration

public static ImmediateScheduler Immediate { get; }

Property Value

Type	Description
ImmediateScheduler

NewThread

Gets a scheduler that schedules work on a new thread using default thread creation options.

Declaration

[Obsolete("This property is no longer supported due to refactoring of the API surface and elimination of platform-specific dependencies. Please add a reference to the System.Reactive.PlatformServices assembly for your target platform and use NewThreadScheduler.Default to obtain an instance of this scheduler type. See http://go.microsoft.com/fwlink/?LinkID=260866 for more information.")]
public static IScheduler NewThread { get; }

Property Value

Type	Description
IScheduler

Now

Gets the current time according to the local machine's system clock.

Declaration

public static DateTimeOffset Now { get; }

Property Value

Type	Description
DateTimeOffset

TaskPool

Gets a scheduler that schedules work on Task Parallel Library (TPL) task pool using the default TaskScheduler.

Declaration

[Obsolete("This property is no longer supported due to refactoring of the API surface and elimination of platform-specific dependencies. Please add a reference to the System.Reactive.PlatformServices assembly for your target platform and use TaskPoolScheduler.Default to obtain an instance of this scheduler type. See http://go.microsoft.com/fwlink/?LinkID=260866 for more information.")]
public static IScheduler TaskPool { get; }

Property Value

Type	Description
IScheduler

ThreadPool

Gets a scheduler that schedules work on the thread pool.

Declaration

[Obsolete("This property is no longer supported due to refactoring of the API surface and elimination of platform-specific dependencies. Consider using Scheduler.Default to obtain the platform's most appropriate pool-based scheduler. In order to access a specific pool-based scheduler, please add a reference to the System.Reactive.PlatformServices assembly for your target platform and use the appropriate scheduler in the System.Reactive.Concurrency namespace. See http://go.microsoft.com/fwlink/?LinkID=260866 for more information.")]
public static IScheduler ThreadPool { get; }

Property Value

Type	Description
IScheduler

Methods

AsLongRunning(IScheduler)

Returns the ISchedulerLongRunning implementation of the specified scheduler, or null if no such implementation is available.

Declaration

public static ISchedulerLongRunning AsLongRunning(this IScheduler scheduler)

Parameters

Type	Name	Description
IScheduler	scheduler	Scheduler to get the ISchedulerLongRunning implementation for.

Returns

Type	Description
ISchedulerLongRunning	The scheduler's ISchedulerLongRunning implementation if available; null otherwise.

Remarks

This helper method is made available for query operator authors in order to discover scheduler services by using the required IServiceProvider pattern, which allows for interception or redefinition of scheduler services.

AsPeriodic(IScheduler)

Returns the IStopwatchProvider implementation of the specified scheduler, or null if no such implementation is available.

Declaration

public static ISchedulerPeriodic AsPeriodic(this IScheduler scheduler)

Parameters

Type	Name	Description
IScheduler	scheduler	Scheduler to get the IStopwatchProvider implementation for.

Returns

Type	Description
ISchedulerPeriodic	The scheduler's IStopwatchProvider implementation if available; null otherwise.

Remarks

This helper method is made available for query operator authors in order to discover scheduler services by using the required IServiceProvider pattern, which allows for interception or redefinition of scheduler services.

Consider using the Scheduler.SchedulePeriodic extension methods for IScheduler in case periodic scheduling is required and emulation of periodic behavior using other scheduler services is desirable. Use of this method is recommended for best-effort use of the periodic scheduling service, where the caller falls back to not using periodic scheduling if this facility wasn't found.

AsStopwatchProvider(IScheduler)

Returns the IStopwatchProvider implementation of the specified scheduler, or null if no such implementation is available.

Declaration

public static IStopwatchProvider AsStopwatchProvider(this IScheduler scheduler)

Parameters

Type	Name	Description
IScheduler	scheduler	Scheduler to get the IStopwatchProvider implementation for.

Returns

Type	Description
IStopwatchProvider	The scheduler's IStopwatchProvider implementation if available; null otherwise.

Remarks

This helper method is made available for query operator authors in order to discover scheduler services by using the required IServiceProvider pattern, which allows for interception or redefinition of scheduler services.

Consider using StartStopwatch(IScheduler) in case a stopwatch is required, but use of emulation stopwatch based on the scheduler's clock is acceptable. Use of this method is recommended for best-effort use of the stopwatch provider scheduler service, where the caller falls back to not using stopwatches if this facility wasn't found.

Catch<TException>(IScheduler, Func<TException, Boolean>)

Returns a scheduler that wraps the original scheduler, adding exception handling for scheduled actions.

Declaration

public static IScheduler Catch<TException>(this IScheduler scheduler, Func<TException, bool> handler)
    where TException : Exception

Parameters

Type	Name	Description
IScheduler	scheduler	Scheduler to apply an exception filter for.
Func<TException, Boolean>	handler	Handler that's run if an exception is caught. The exception will be rethrown if the handler returns false.

Returns

Type	Description
IScheduler	Wrapper around the original scheduler, enforcing exception handling.

Type Parameters

Name	Description
TException	Type of the exception to check for.

Exceptions

Type	Condition
ArgumentNullException	scheduler or handler is null.

DisableOptimizations(IScheduler)

Returns a scheduler that represents the original scheduler, without any of its interface-based optimizations (e.g. long running scheduling).

Declaration

public static IScheduler DisableOptimizations(this IScheduler scheduler)

Parameters

Type	Name	Description
IScheduler	scheduler	Scheduler to disable all optimizations for.

Returns

Type	Description
IScheduler	Proxy to the original scheduler but without any optimizations enabled.

Exceptions

Type	Condition
ArgumentNullException	scheduler is null.

DisableOptimizations(IScheduler, Type[])

Returns a scheduler that represents the original scheduler, without the specified set of interface-based optimizations (e.g. long running scheduling).

Declaration

public static IScheduler DisableOptimizations(this IScheduler scheduler, params Type[] optimizationInterfaces)

Parameters

Type	Name	Description
IScheduler	scheduler	Scheduler to disable the specified optimizations for.
Type[]	optimizationInterfaces	Types of the optimization interfaces that have to be disabled.

Returns

Type	Description
IScheduler	Proxy to the original scheduler but without the specified optimizations enabled.

Exceptions

Type	Condition
ArgumentNullException	scheduler or optimizationInterfaces is null.

Normalize(TimeSpan)

Normalizes the specified TimeSpan value to a positive value.

Declaration

public static TimeSpan Normalize(TimeSpan timeSpan)

Parameters

Type	Name	Description
TimeSpan	timeSpan	The TimeSpan value to normalize.

Returns

Type	Description
TimeSpan	The specified TimeSpan value if it is zero or positive; otherwise, TimeSpan.Zero.

Schedule(IScheduler, Action)

Schedules an action to be executed.

Declaration

public static IDisposable Schedule(this IScheduler scheduler, Action action)

Parameters

Type	Name	Description
IScheduler	scheduler	Scheduler to execute the action on.
Action	action	Action to execute.

Returns

Type	Description
IDisposable	The disposable object used to cancel the scheduled action (best effort).

Exceptions

Type	Condition
ArgumentNullException	scheduler or action is null.

Schedule(IScheduler, Action<Action>)

Schedules an action to be executed recursively.

Declaration

public static IDisposable Schedule(this IScheduler scheduler, Action<Action> action)

Parameters

Type	Name	Description
IScheduler	scheduler	Scheduler to execute the recursive action on.
Action<Action>	action	Action to execute recursively. The parameter passed to the action is used to trigger recursive scheduling of the action.

Returns

Type	Description
IDisposable	The disposable object used to cancel the scheduled action (best effort).

Exceptions

Type	Condition
ArgumentNullException	scheduler or action is null.

Schedule(IScheduler, DateTimeOffset, Action)

Schedules an action to be executed at the specified absolute due time.

Declaration

public static IDisposable Schedule(this IScheduler scheduler, DateTimeOffset dueTime, Action action)

Parameters

Type	Name	Description
IScheduler	scheduler	Scheduler to execute the action on.
DateTimeOffset	dueTime	Absolute time at which to execute the action.
Action	action	Action to execute.

Returns

Type	Description
IDisposable	The disposable object used to cancel the scheduled action (best effort).

Exceptions

Type	Condition
ArgumentNullException	scheduler or action is null.

Schedule(IScheduler, DateTimeOffset, Action<Action<DateTimeOffset>>)

Schedules an action to be executed recursively at a specified absolute due time.

Declaration

public static IDisposable Schedule(this IScheduler scheduler, DateTimeOffset dueTime, Action<Action<DateTimeOffset>> action)

Parameters

Type	Name	Description
IScheduler	scheduler	Scheduler to execute the recursive action on.
DateTimeOffset	dueTime	Absolute time at which to execute the action for the first time.
Action<Action<DateTimeOffset>>	action	Action to execute recursively. The parameter passed to the action is used to trigger recursive scheduling of the action at the specified absolute time.

Returns

Type	Description
IDisposable	The disposable object used to cancel the scheduled action (best effort).

Exceptions

Type	Condition
ArgumentNullException	scheduler or action is null.

Schedule(IScheduler, TimeSpan, Action)

Schedules an action to be executed after the specified relative due time.

Declaration

public static IDisposable Schedule(this IScheduler scheduler, TimeSpan dueTime, Action action)

Parameters

Type	Name	Description
IScheduler	scheduler	Scheduler to execute the action on.
TimeSpan	dueTime	Relative time after which to execute the action.
Action	action	Action to execute.

Returns

Type	Description
IDisposable	The disposable object used to cancel the scheduled action (best effort).

Exceptions

Type	Condition
ArgumentNullException	scheduler or action is null.

Schedule(IScheduler, TimeSpan, Action<Action<TimeSpan>>)

Schedules an action to be executed recursively after a specified relative due time.

Declaration

public static IDisposable Schedule(this IScheduler scheduler, TimeSpan dueTime, Action<Action<TimeSpan>> action)

Parameters

Type	Name	Description
IScheduler	scheduler	Scheduler to execute the recursive action on.
TimeSpan	dueTime	Relative time after which to execute the action for the first time.
Action<Action<TimeSpan>>	action	Action to execute recursively. The parameter passed to the action is used to trigger recursive scheduling of the action at the specified relative time.

Returns

Type	Description
IDisposable	The disposable object used to cancel the scheduled action (best effort).

Exceptions

Type	Condition
ArgumentNullException	scheduler or action is null.

Schedule<TState>(IScheduler, TState, Action<TState, Action<TState>>)

Schedules an action to be executed recursively.

Declaration

public static IDisposable Schedule<TState>(this IScheduler scheduler, TState state, Action<TState, Action<TState>> action)

Parameters

Type	Name	Description
IScheduler	scheduler	Scheduler to execute the recursive action on.
TState	state	State passed to the action to be executed.
Action<TState, Action<TState>>	action	Action to execute recursively. The last parameter passed to the action is used to trigger recursive scheduling of the action, passing in recursive invocation state.

Returns

Type	Description
IDisposable	The disposable object used to cancel the scheduled action (best effort).

Type Parameters

Name	Description
TState	The type of the state passed to the scheduled action.

Exceptions

Type	Condition
ArgumentNullException	scheduler or action is null.

Schedule<TState>(IScheduler, TState, DateTimeOffset, Action<TState, Action<TState, DateTimeOffset>>)

Schedules an action to be executed recursively at a specified absolute due time.

Declaration

public static IDisposable Schedule<TState>(this IScheduler scheduler, TState state, DateTimeOffset dueTime, Action<TState, Action<TState, DateTimeOffset>> action)

Parameters

Type	Name	Description
IScheduler	scheduler	Scheduler to execute the recursive action on.
TState	state	State passed to the action to be executed.
DateTimeOffset	dueTime	Absolute time at which to execute the action for the first time.
Action<TState, Action<TState, DateTimeOffset>>	action	Action to execute recursively. The last parameter passed to the action is used to trigger recursive scheduling of the action, passing in the recursive due time and invocation state.

Returns

Type	Description
IDisposable	The disposable object used to cancel the scheduled action (best effort).

Type Parameters

Name	Description
TState	The type of the state passed to the scheduled action.

Exceptions

Type	Condition
ArgumentNullException	scheduler or action is null.

Schedule<TState>(IScheduler, TState, TimeSpan, Action<TState, Action<TState, TimeSpan>>)

Schedules an action to be executed recursively after a specified relative due time.

Declaration

public static IDisposable Schedule<TState>(this IScheduler scheduler, TState state, TimeSpan dueTime, Action<TState, Action<TState, TimeSpan>> action)

Parameters

Type	Name	Description
IScheduler	scheduler	Scheduler to execute the recursive action on.
TState	state	State passed to the action to be executed.
TimeSpan	dueTime	Relative time after which to execute the action for the first time.
Action<TState, Action<TState, TimeSpan>>	action	Action to execute recursively. The last parameter passed to the action is used to trigger recursive scheduling of the action, passing in the recursive due time and invocation state.

Returns

Type	Description
IDisposable	The disposable object used to cancel the scheduled action (best effort).

Type Parameters

Name	Description
TState	The type of the state passed to the scheduled action.

Exceptions

Type	Condition
ArgumentNullException	scheduler or action is null.

ScheduleLongRunning(ISchedulerLongRunning, Action<ICancelable>)

Schedules an action to be executed.

Declaration

public static IDisposable ScheduleLongRunning(this ISchedulerLongRunning scheduler, Action<ICancelable> action)

Parameters

Type	Name	Description
ISchedulerLongRunning	scheduler	Scheduler to execute the action on.
Action<ICancelable>	action	Action to execute.

Returns

Type	Description
IDisposable	The disposable object used to cancel the scheduled action (best effort).

Exceptions

Type	Condition
ArgumentNullException	scheduler or action is null.

SchedulePeriodic(IScheduler, TimeSpan, Action)

Schedules a periodic piece of work by dynamically discovering the scheduler's capabilities. If the scheduler supports periodic scheduling, the request will be forwarded to the periodic scheduling implementation. If the scheduler provides stopwatch functionality, the periodic task will be emulated using recursive scheduling with a stopwatch to correct for time slippage. Otherwise, the periodic task will be emulated using recursive scheduling.

Declaration

public static IDisposable SchedulePeriodic(this IScheduler scheduler, TimeSpan period, Action action)

Parameters

Type	Name	Description
IScheduler	scheduler	Scheduler to execute the action on.
TimeSpan	period	Period for running the work periodically.
Action	action	Action to be executed.

Returns

Type	Description
IDisposable	The disposable object used to cancel the scheduled recurring action (best effort).

Exceptions

Type	Condition
ArgumentNullException	scheduler or action is null.
ArgumentOutOfRangeException	period is less than TimeSpan.Zero.

SchedulePeriodic<TState>(IScheduler, TState, TimeSpan, Action<TState>)

Schedules a periodic piece of work by dynamically discovering the scheduler's capabilities. If the scheduler supports periodic scheduling, the request will be forwarded to the periodic scheduling implementation. If the scheduler provides stopwatch functionality, the periodic task will be emulated using recursive scheduling with a stopwatch to correct for time slippage. Otherwise, the periodic task will be emulated using recursive scheduling.

Declaration

public static IDisposable SchedulePeriodic<TState>(this IScheduler scheduler, TState state, TimeSpan period, Action<TState> action)

Parameters

Type	Name	Description
IScheduler	scheduler	Scheduler to execute the action on.
TState	state	State passed to the action to be executed.
TimeSpan	period	Period for running the work periodically.
Action<TState>	action	Action to be executed.

Returns

Type	Description
IDisposable	The disposable object used to cancel the scheduled recurring action (best effort).

Type Parameters

Name	Description
TState	The type of the state passed to the scheduled action.

Exceptions

Type	Condition
ArgumentNullException	scheduler or action is null.
ArgumentOutOfRangeException	period is less than TimeSpan.Zero.

SchedulePeriodic<TState>(IScheduler, TState, TimeSpan, Func<TState, TState>)

Schedules a periodic piece of work by dynamically discovering the scheduler's capabilities. If the scheduler supports periodic scheduling, the request will be forwarded to the periodic scheduling implementation. If the scheduler provides stopwatch functionality, the periodic task will be emulated using recursive scheduling with a stopwatch to correct for time slippage. Otherwise, the periodic task will be emulated using recursive scheduling.

Declaration

public static IDisposable SchedulePeriodic<TState>(this IScheduler scheduler, TState state, TimeSpan period, Func<TState, TState> action)

Parameters

Type	Name	Description
IScheduler	scheduler	The scheduler to run periodic work on.
TState	state	Initial state passed to the action upon the first iteration.
TimeSpan	period	Period for running the work periodically.
Func<TState, TState>	action	Action to be executed, potentially updating the state.

Returns

Type	Description
IDisposable	The disposable object used to cancel the scheduled recurring action (best effort).

Type Parameters

Name	Description
TState	The type of the state passed to the scheduled action.

Exceptions

Type	Condition
ArgumentNullException	scheduler or action is null.
ArgumentOutOfRangeException	period is less than TimeSpan.Zero.

StartStopwatch(IScheduler)

Starts a new stopwatch object by dynamically discovering the scheduler's capabilities. If the scheduler provides stopwatch functionality, the request will be forwarded to the stopwatch provider implementation. Otherwise, the stopwatch will be emulated using the scheduler's notion of absolute time.

Declaration

public static IStopwatch StartStopwatch(this IScheduler scheduler)

Parameters

Type	Name	Description
IScheduler	scheduler	Scheduler to obtain a stopwatch for.

Returns

Type	Description
IStopwatch	New stopwatch object; started at the time of the request.

Remarks

The resulting stopwatch object can have non-monotonic behavior.

Exceptions

Type	Condition
ArgumentNullException	scheduler is null.