Fixed async issues

Author: zbalkan

Apps/LogExporterApp/App.cs

@@ -46,6 +46,7 @@ public sealed class App : IDnsApplication, IDnsQueryLogger
         long _droppedCount;
         DateTime _lastDropLog = DateTime.UtcNow;
         static readonly TimeSpan DropLogInterval = TimeSpan.FromSeconds(5);
+        long _lastDropTicks;
         #endregion variables
 
         #region constructor
@@ -170,11 +171,11 @@ public Task InsertLogAsync(DateTime timestamp, DnsDatagram request,
                 {
                     Interlocked.Increment(ref _droppedCount);
 
-                    DateTime now = DateTime.UtcNow;
-                    if (now - _lastDropLog >= DropLogInterval)
+                    long nowTicks = DateTime.UtcNow.Ticks;
+                    long lastTicks = Volatile.Read(ref _lastDropTicks);
+                    if (new TimeSpan(nowTicks - lastTicks) >= DropLogInterval && Interlocked.CompareExchange(ref _lastDropTicks, nowTicks, lastTicks) == lastTicks)
                     {
                         long dropped = Interlocked.Exchange(ref _droppedCount, 0);
-                        _lastDropLog = now;
                         _dnsServer?.WriteLog($"Log export queue full; dropped {dropped} entries over last {DropLogInterval.TotalSeconds:F0}s.");
                     }
                 }
@@ -265,9 +266,9 @@ private async Task DrainRemainingLogs(List<LogEntry> batch, CancellationToken to
                     }
                 }
 
-                if (batch.Count > 0 && !token.IsCancellationRequested)
+                if (batch.Count > 0)
                 {
-                    await _sinkDispatcher.DispatchAsync(batch, token).ConfigureAwait(false);
+                    await _sinkDispatcher.DispatchAsync(batch, CancellationToken.None).ConfigureAwait(false);
                     batch.Clear();
                 }
             }