Switching back to CancellationEvent usage instead of CancellationToken.WaitHandle

Closes #2447

Author: odinserj

Diff for: src/Hangfire.Core/Common/CancellationTokenExtentions.cs

@@ -66,6 +66,9 @@ public static bool Wait(this CancellationToken cancellationToken, TimeSpan timeo
             var elapsedThreshold = TimeSpan.FromMilliseconds(500);
             var protectionTime = TimeSpan.FromSeconds(1);
 
+            // There was a precedent of the following message logged when CancellationToken.WaitHandle
+            // was used directly, instead of having our custom CancellationEvent class used, please see
+            // https://github.com/HangfireIO/Hangfire/issues/2447
             if (!cancellationToken.IsCancellationRequested &&
                 timeout >= timeoutThreshold &&
                 stopwatch.Elapsed < elapsedThreshold)

Diff for: src/Hangfire.SqlServer/SqlServerJobQueue.cs

@@ -22,6 +22,7 @@
 using System.Linq;
 using System.Threading;
 using Hangfire.Annotations;
+using Hangfire.Common;
 using Hangfire.Storage;
 
 // ReSharper disable RedundantAnonymousTypePropertyName
@@ -124,7 +125,8 @@ private SqlServerTimeoutJob DequeueUsingSlidingInvisibilityTimeout(string[] queu
             var queuesString = String.Join("_", queues.OrderBy(static x => x));
             var resource = Tuple.Create(_storage, queuesString);
 
-            var waitArray = GetWaitArrayForQueueSignals(_storage, queues, cancellationToken);
+            using var cancellationEvent = cancellationToken.GetCancellationEvent();
+            var waitArray = GetWaitArrayForQueueSignals(_storage, queues, cancellationEvent);
 
             SemaphoreSlim semaphore = null;
 
@@ -221,7 +223,8 @@ private SqlServerTransactionJob DequeueUsingTransaction(string[] queues, Cancell
                 ? _options.QueuePollInterval
                 : TimeSpan.FromSeconds(1);
 
-            var waitArray = GetWaitArrayForQueueSignals(_storage, queues, cancellationToken);
+            using var cancellationEvent = cancellationToken.GetCancellationEvent();
+            var waitArray = GetWaitArrayForQueueSignals(_storage, queues, cancellationEvent);
 
             while (!cancellationToken.IsCancellationRequested)
             {
@@ -305,11 +308,11 @@ private static DbCommand CreateTransactionalFetchCommand(
                 .AddExpandedParameter("@queues", queues, DbType.String);
         }
 
-        private static WaitHandle[] GetWaitArrayForQueueSignals(SqlServerStorage storage, string[] queues, CancellationToken cancellationToken)
+        private static WaitHandle[] GetWaitArrayForQueueSignals(SqlServerStorage storage, string[] queues, CancellationTokenExtentions.CancellationEvent cancellationEvent)
         {
             var waitList = new List<WaitHandle>(capacity: queues.Length + 1)
             {
-                cancellationToken.WaitHandle
+                cancellationEvent.WaitHandle
             };
 
             foreach (var queue in queues)