private static async Task <IReadOnlyList <IStorageItem> > EnumerateFileByFile(BaseStorageFolder rootFolder, uint startFrom, uint itemsToIterate)
{
var tempList = new List <IStorageItem>();
for (var i = startFrom; i < startFrom + itemsToIterate; i++)
{
IStorageItem item;
try
{
var results = await rootFolder.GetItemsAsync(i, 1);
item = results?.FirstOrDefault();
if (item == null)
{
break;
}
}
catch (NotImplementedException)
{
break;
}
catch (Exception ex) when(
ex is UnauthorizedAccessException ||
ex is FileNotFoundException ||
(uint)ex.HResult == 0x80070490) // ERROR_NOT_FOUND
{
continue;
}
tempList.Add(item);
}
return(tempList);
}
public static async Task <List <ListedItem> > ListEntries(
BaseStorageFolder rootFolder,
StorageFolderWithPath currentStorageFolder,
string returnformat,
Type sourcePageType,
CancellationToken cancellationToken,
int countLimit,
Func <List <ListedItem>, Task> intermediateAction,
Dictionary <string, BitmapImage> defaultIconPairs = null
)
{
var sampler = new IntervalSampler(500);
var tempList = new List <ListedItem>();
uint count = 0;
var firstRound = true;
while (true)
{
IReadOnlyList <IStorageItem> items;
uint maxItemsToRetrieve = 300;
if (intermediateAction == null)
{
// without intermediate action increase batches significantly
maxItemsToRetrieve = 1000;
}
else if (firstRound)
{
maxItemsToRetrieve = 32;
firstRound = false;
}
try
{
items = await rootFolder.GetItemsAsync(count, maxItemsToRetrieve);
if (items == null || items.Count == 0)
{
break;
}
}
catch (NotImplementedException)
{
break;
}
catch (Exception ex) when(
ex is UnauthorizedAccessException ||
ex is FileNotFoundException ||
(uint)ex.HResult == 0x80070490) // ERROR_NOT_FOUND
{
// If some unexpected exception is thrown - enumerate this folder file by file - just to be sure
items = await EnumerateFileByFile(rootFolder, count, maxItemsToRetrieve);
}
foreach (var item in items)
{
if (item.IsOfType(StorageItemTypes.Folder))
{
var folder = await AddFolderAsync(item.AsBaseStorageFolder(), currentStorageFolder, returnformat, cancellationToken);
if (folder != null)
{
if (defaultIconPairs?.ContainsKey(string.Empty) ?? false)
{
folder.SetDefaultIcon(defaultIconPairs[string.Empty]);
}
tempList.Add(folder);
}
}
else
{
var fileEntry = await AddFileAsync(item.AsBaseStorageFile(), currentStorageFolder, returnformat, cancellationToken);
if (fileEntry != null)
{
if (defaultIconPairs != null)
{
if (!string.IsNullOrEmpty(fileEntry.FileExtension))
{
var lowercaseExtension = fileEntry.FileExtension.ToLowerInvariant();
if (defaultIconPairs.ContainsKey(lowercaseExtension))
{
fileEntry.SetDefaultIcon(defaultIconPairs[lowercaseExtension]);
}
}
}
tempList.Add(fileEntry);
}
}
if (cancellationToken.IsCancellationRequested)
{
break;
}
}
count += maxItemsToRetrieve;
if (countLimit > -1 && count >= countLimit)
{
break;
}
if (intermediateAction != null && (items.Count == maxItemsToRetrieve || sampler.CheckNow()))
{
await intermediateAction(tempList);
// clear the temporary list every time we do an intermediate action
tempList.Clear();
}
}
return(tempList);
}
