/// <summary>
/// Awaits for a given task while periodically calling <paramref name="action"/>.
/// </summary>
/// <typeparam name="TResult">Return type of the task</typeparam>
/// <param name="task">The task to await</param>
/// <param name="period">Period at which to call <paramref name="action"/></param>
/// <param name="action">Action to periodically call. The action receives elapsed time since this method was called.</param>
/// <param name="reportImmediately">Whether <paramref name="action"/> should be called immediately.</param>
/// <param name="reportAtEnd">Whether <paramref name="action"/> should be called at when </param>
/// <returns>The result of the task.</returns>
public static async Task <TResult> AwaitWithProgressReporting <TResult>(
Task <TResult> task,
TimeSpan period,
Action <TimeSpan> action,
bool reportImmediately = true,
bool reportAtEnd = true)
{
var startTime = DateTime.UtcNow;
var timer = new StoppableTimer(
() =>
{
action(DateTime.UtcNow.Subtract(startTime));
},
dueTime: reportImmediately ? 0 : (int)period.TotalMilliseconds,
period: (int)period.TotalMilliseconds);
using (timer)
{
await task.ContinueWith(t =>
{
return(timer.StopAsync());
}).Unwrap();
// report once at the end
if (reportAtEnd)
{
action(DateTime.UtcNow.Subtract(startTime));
}
return(await task);
}
}
/// <summary>
/// Awaits given tasks, periodically calling <paramref name="action"/>.
/// </summary>
/// <typeparam name="TItem">Type of the collection to iterate over.</typeparam>
/// <typeparam name="TResult">Type of the tasks' result.</typeparam>
/// <param name="collection">Collection to iterate over.</param>
/// <param name="taskSelector">Function to use to select a task for a given item from the given collection.</param>
/// <param name="action">
/// Action to call periodically (as specified by <paramref name="period"/>).
/// The action receives
/// (1) total elapsed time,
/// (2) all original items, and
/// (3) a collection of non-finished items
/// </param>
/// <param name="period">Period at which to call <paramref name="action"/>.</param>
/// <returns>The results of inidvidual tasks.</returns>
public static async Task <TResult[]> AwaitWithProgressReporting <TItem, TResult>(
IReadOnlyCollection <TItem> collection,
Func <TItem, Task <TResult> > taskSelector,
Action <TimeSpan, IReadOnlyCollection <TItem>, IReadOnlyCollection <TItem> > action,
TimeSpan period)
{
var startTime = DateTime.UtcNow;
var timer = new StoppableTimer(
() =>
{
var elapsed = DateTime.UtcNow.Subtract(startTime);
var remainingItems = collection
.Where(item => !taskSelector(item).IsCompleted)
.ToList();
action(elapsed, collection, remainingItems);
},
dueTime: 0,
period: (int)period.TotalMilliseconds);
using (timer)
{
var result = await Task.WhenAll(collection.Select(item => taskSelector(item)));
await timer.StopAsync();
// report once at the end
action(DateTime.UtcNow.Subtract(startTime), collection, CollectionUtilities.EmptyArray <TItem>());
return(result);
}
}