private async void OnCacheFileChangedAsync(object sender, FileSystemEventArgs args)
{
// avoid the high cost of computing the added / removed accounts if nobody listens to this
if (CacheChanged == null)
{
return;
}
try
{
IEnumerable <string> added;
IEnumerable <string> removed;
using (CreateCrossPlatLock(_storageCreationProperties))
{
var currentAccountIds = await GetAccountIdentifiersAsync(_storageCreationProperties, _logger).ConfigureAwait(false);
var intersect = currentAccountIds.Intersect(_knownAccountIds);
removed = _knownAccountIds.Except(intersect);
added = currentAccountIds.Except(intersect);
_knownAccountIds = currentAccountIds;
}
if (added.Any() || removed.Any())
{
CacheChanged.Invoke(sender, new CacheChangedEventArgs(added, removed));
}
}
catch (Exception e)
{
// Never let this throw, just log errors
_logger.LogWarning($"Exception within File Watcher : {e}");
}
}
private async void OnCacheFileChangedAsync(object sender, FileSystemEventArgs args)
{
try
{
IEnumerable <string> added = Enumerable.Empty <string>();
IEnumerable <string> removed = Enumerable.Empty <string>();
using (CreateCrossPlatLock(_storageCreationProperties))
{
var currentAccountIds = await GetAccountIdentifiersAsync(_storageCreationProperties).ConfigureAwait(false);
var intersect = currentAccountIds.Intersect(_knownAccountIds);
removed = _knownAccountIds.Except(intersect);
added = currentAccountIds.Except(intersect);
_knownAccountIds = currentAccountIds;
}
if (added.Any() || removed.Any())
{
CacheChanged?.Invoke(sender, new CacheChangedEventArgs(added, removed));
}
}
catch (Exception e)
{
// Never let this throw, just log errors
_logger.TraceEvent(TraceEventType.Warning, /*id*/ 0, $"Exception within File Watcher : {e}");
}
}
public void RefreshCache(string fieldName = null)
{
_orderByField = fieldName;
Context.Refresh(RefreshMode.StoreWins, Context.Contacts);
if (_contactsCache == null)
{
_contactsCache = new SynchronizedObservableCollection <Contact>(new ObservableCollection <Contact>());
}
// _contactsCache.Clear();
_contactsCache = new SynchronizedObservableCollection <Contact>(new ObservableCollection <Contact>(orderContactsByField(fieldName)));
if (CacheChanged != null)
{
CacheChanged.Invoke(this, EventArgs.Empty);
}
//foreach (Contact contact in orderContactsByField(fieldName))
//{
// _contactsCache.Add(contact);
//}
}
private void OnCacheChanged()
{
CacheChanged?.Invoke(this, EventArgs.Empty);
}
// Called by the timer to make a request for data
public async void FetchData()
{
// Stop the timer so we don't get fired again unless data is requested
_timer.Stop();
if (_requestInProgress != null)
{
// Verify if an active request is still needed
if (_request.Intersects(_requestInProgress))
{
return;
}
// Cancel the existing request
_cancelTokenSource.Cancel();
}
ItemIndexRange nextRequest = GetFirstRequestBlock(_maxBatchFetchSize);
if (nextRequest != null)
{
_cancelTokenSource = new CancellationTokenSource();
CancellationToken ct = _cancelTokenSource.Token;
_requestInProgress = nextRequest;
T[] data = null;
try
{
// Use the callback to get the data, passing in a cancellation token
data = await _fetchDataCallback(nextRequest, ct);
if (!ct.IsCancellationRequested)
{
for (int i = 0; i < data.Length; i++)
{
int cacheIndex = nextRequest.FirstIndex + i;
T oldItem = this[cacheIndex];
T newItem = data[i];
if (!newItem.Equals(oldItem))
{
this[cacheIndex] = newItem;
// Fire CacheChanged so that the datasource can fire its INCC event, and do other work based on the item having data
#pragma warning disable SA1118 // Parameter must not span multiple lines
CacheChanged?.Invoke(this,
new CacheChangedEventArgs <T>
{
OldItem = oldItem,
NewItem = newItem,
ItemIndex = cacheIndex
});
#pragma warning restore SA1118 // Parameter must not span multiple lines
}
}
_request.Subtract(new ItemIndexRange(nextRequest.FirstIndex, (uint)data.Length));
}
}
// Try/Catch is needed as cancellation is via an exception
catch (OperationCanceledException)
{
}
finally
{
_requestInProgress = null;
// Start another request if required
FetchData();
}
}
}
