/// <summary>
/// Asynchronously runs <paramref name="delegateFunction"/> for every item in the given collection
/// </summary>
/// <typeparam name="T">Type of the collection item</typeparam>
/// <param name="delegateFunction">The function to asynchronously run</param>
/// <param name="collection">The collection to be enumerated</param>
/// <exception cref="InvalidOperationException">Thrown if execution starts before the end of another operation</exception>
public async Task RunForEach <T>(IEnumerable <T> collection, ForEachItemAsync <T> delegateFunction)
{
if (RunningTasks.Count > 0)
{
throw new InvalidOperationException(Properties.Resources.AsyncFor_ErrorNoConcurrentExecution);
}
var exceptions = new List <Exception>();
var taskItemQueue = new Queue <T>();
foreach (var item in collection)
{
taskItemQueue.Enqueue(item);
}
TotalTasks = taskItemQueue.Count;
// While there's either more tasks to start or while there's still tasks running
while (taskItemQueue.Count > 0 || (taskItemQueue.Count == 0 && RunningTasks.Count > 0))
{
if ((BatchSize < 1 || RunningTasks.Count < BatchSize) && taskItemQueue.Count > 0)
{
// We can run more tasks
// Get the next task item to run
var item = taskItemQueue.Dequeue(); // The item in Collection to process
// Start the task
var tTask = Task.Run(async() =>
{
await delegateFunction(item).ConfigureAwait(false);
IncrementCompletedTasks();
});
// Either wait for it or move on
if (RunSynchronously)
{
await tTask.ConfigureAwait(false);
}
else
{
RunningTasks.Add(tTask);
}
}
else
{
if (RunningTasks.Count > 0)
{
// We can't start any more tasks, so we have to wait on one.
await Task.WhenAny(RunningTasks).ConfigureAwait(false);
// Remove completed tasks
for (var count = RunningTasks.Count - 1; count >= 0; count--)
{
if (RunningTasks[count].Exception != null)
{
var ex = RunningTasks[count].Exception;
if (ex is AggregateException aggregateEx && aggregateEx.InnerExceptions.Count == 1)
{
exceptions.Add(aggregateEx.InnerExceptions.First());
}
else
{
exceptions.Add(RunningTasks[count].Exception);
}
RunningTasks.RemoveAt(count);
}
else if (RunningTasks[count].IsCompleted)
{
RunningTasks.RemoveAt(count);
}
}
}
