public static SupercedableTaskState <TSource, TResult> CheckSupercede(SupercedableTaskState <TSource, TResult> current, TSource source, Func <TSource, CancellationToken, TResult> function)
{
if (current == null || current.ShouldBeSuperceded(source))
{
return(ForceSupercede(current, source, function));
}
return(current);
}
public static SupercedableTaskState <TSource, TResult> CheckSupercede(SupercedableTaskState <TSource, TResult> current, TSource source, TResult value)
{
if (current == null || current.ShouldBeSuperceded(source, value))
{
return(ForceSupercede(current, source, value));
}
return(current);
}
public void StartNew(TSource source, Func <TSource, CancellationToken, TResult> function)
{
if (function == null)
{
throw new ArgumentNullException("function");
}
using (SynchronizedStateChange <SupercedableTaskState <TSource, TResult> > stateChange = ChangeState())
stateChange.NewState = SupercedableTaskState <TSource, TResult> .CheckSupercede(stateChange.CurrentState, source, function);
}
private static SupercedableTaskState <TSource, TResult> ForceSupercede(SupercedableTaskState <TSource, TResult> current, Func <SupercedableTaskState <TSource, TResult> > createFollowing)
{
SupercedableTaskState <TSource, TResult> following;
try
{
if (current != null && !current.IsCompleted && !current.IsCancellationRequested)
{
current.OnPrepareSupercede();
}
}
finally
{
following = createFollowing();
try
{
if (current != null)
{
try { current.OnBeforeSupercededBy(following); }
finally { following.OnBeforeSuperceding(current); }
}
}
finally
{
if (current != null && !current.IsCompleted && !current.IsCancellationRequested)
{
try
{
try
{
if (!current.IsCompleted && !current.IsCancellationRequested)
{
current.Cancel();
}
}
finally { current.OnAfterSupercededBy(following); }
}
finally { following.OnAfterSuperceding(current); }
}
}
}
return(following);
}
public void StartNew(TSource source, TResult value)
{
using (SynchronizedStateChange <SupercedableTaskState <TSource, TResult> > stateChange = ChangeState())
stateChange.NewState = SupercedableTaskState <TSource, TResult> .CheckSupercede(stateChange.CurrentState, source, value);
}
public static SupercedableTaskState <TSource, TResult> ForceSupercede(SupercedableTaskState <TSource, TResult> current, TSource source, TResult value)
{
return(ForceSupercede(current, () => new SupercedableTaskState <TSource, TResult>(source, value)));
}
public static SupercedableTaskState <TSource, TResult> ForceSupercede(SupercedableTaskState <TSource, TResult> current, TSource source, Func <TSource, CancellationToken, TResult> function)
{
return(ForceSupercede(current, () => new SupercedableTaskState <TSource, TResult>(source, function)));
}
protected virtual void OnAfterSuperceding(SupercedableTaskState <TSource, TResult> previous)
{
}
protected virtual void OnAfterSupercededBy(SupercedableTaskState <TSource, TResult> following)
{
}
protected virtual void OnBeforeSuperceding(SupercedableTaskState <TSource, TResult> current)
{
}