/// <summary>
/// Repeatedly yields a lazy invocation attempt of the factory as an enumerable.
/// </summary>
/// <param name="default">The result value when not successful.</param>
public static IEnumerable <Lazy <Attempt <T> > > Get <T>(Func <T> factory, T @default = default(T))
{
while (true)
{
yield return(new Lazy <Attempt <T> >(() => Attempt.Get(factory, @default)));
}
}
/// <summary>
/// Returns files that haven't changed over a period of time.
/// </summary>
/// <param name="source">Files to check.</param>
/// <param name="interval">Time to wait between checking the files.</param>
/// <param name="cancellationToken">Token to cancel the wait between checks.</param>
/// <returns>Files that haven't changed.</returns>
public static FileInfo[] GetUnchangedFiles(this IEnumerable <FileInfo> source, TimeSpan interval,
CancellationToken cancellationToken = default(CancellationToken))
{
if (source == null)
{
throw new ArgumentNullException("source");
}
var e = source.Select(f => new
{
FileInfo = f,
HashAttempt = Attempt.Get(() => f.ComputeFileHash())
}).Where(f => f.HashAttempt.Succeeded);
// ReSharper disable PossibleMultipleEnumeration
var files = e.ToArray();
try
{
Task.Delay(interval, cancellationToken)
// ReSharper disable once MethodSupportsCancellation
.Wait();
}
catch (AggregateException ex)
{
ex.Handle(x => x is OperationCanceledException);
}
cancellationToken.ThrowIfCancellationRequested();
return(e.Join(files, x => x.FileInfo.FullName, x => x.FileInfo.FullName, Tuple.Create)
.Where(x =>
{
try
{
return x.Item1.FileInfo.Length == x.Item2.FileInfo.Length &&
x.Item1.FileInfo.LastWriteTimeUtc == x.Item2.FileInfo.LastWriteTimeUtc &&
x.Item1.HashAttempt.Value == x.Item2.HashAttempt.Value;
}
catch (IOException)
{
return false;
}
})
.Select(x => x.Item1.FileInfo).ToArray());
// ReSharper restore PossibleMultipleEnumeration
}
/// <summary>
/// Invokes the factory, using the source as input, suppressing any thrown exception.
/// </summary>
/// <param name="default">The result value when not successful.</param>
public static Attempt <TResult> AttemptGet <TSource, TResult>(this TSource source, Func <TSource, TResult> factory,
TResult @default = default(TResult))
{
return(Attempt.Get(() => factory(source)));
}
public static Task <T> StartNew <T>(this TaskFactory taskFactory, Func <T> function, CancellationToken cancellationToken, TaskCreationOptions creationOptions)
{
var taskScheduler = Attempt.Get(TaskScheduler.FromCurrentSynchronizationContext).Value ?? TaskScheduler.Default;
return(taskFactory.StartNew(function, cancellationToken, creationOptions, taskScheduler));
}
