Avoid using the CancellationToken.WaitHandle property (#1209)

* Avoid using the CancellationToken.WaitHandle property

Looks like there's a bug in .NET related to the given property that lead
to the high CPU spikes after hours of running. The problem has gone
away, when we stopped to use the CT.WaitHandle property.

* Tune expected delay for .NET Core 1.0 a bit

* Fix the license file name in the psake project

* Fix LICENSE.md file extention in nuspec files

nuspecs/Hangfire.AspNetCore.nuspec

@@ -62,7 +62,7 @@
 
     <file src="..\src\Hangfire.AspNetCore\**\*.cs" target="src" exclude="**\obj*\**\*.cs" />
 
-    <file src="LICENSE" />
+    <file src="LICENSE.md" />
     <file src="NOTICES" />
     <file src="COPYING" />
     <file src="COPYING.LESSER" />

nuspecs/Hangfire.Core.nuspec

@@ -175,7 +175,7 @@
 
     <file src="..\src\Hangfire.Core\**\*.cs;..\src\Hangfire.Core\**\*.cshtml" target="src" exclude="**\obj*\**\*.cs" />
 
-    <file src="LICENSE" />
+    <file src="LICENSE.md" />
     <file src="NOTICES" />
     <file src="COPYING" />
     <file src="COPYING.LESSER" />

nuspecs/Hangfire.SqlServer.MSMQ.nuspec

@@ -43,7 +43,7 @@
     <file src="net45\Hangfire.SqlServer.Msmq.xml" target="lib\net45" />
     <file src="net45\Hangfire.SqlServer.Msmq.pdb" target="lib\net45" />
     <file src="..\src\Hangfire.SqlServer.Msmq\**\*.cs" target="src" exclude="**\obj*\**\*.cs" />
-    <file src="LICENSE" />
+    <file src="LICENSE.md" />
     <file src="NOTICES" />
     <file src="COPYING" />
     <file src="COPYING.LESSER" />

nuspecs/Hangfire.SqlServer.nuspec

@@ -122,7 +122,7 @@
     <file src="Tools\DefaultInstall.sql" target="tools\install.sql" />
     <file src="..\src\Hangfire.SqlServer\**\*.cs" target="src" exclude="**\obj*\**\*.cs" />
 
-    <file src="LICENSE" />
+    <file src="LICENSE.md" />
     <file src="NOTICES" />
     <file src="COPYING" />
     <file src="COPYING.LESSER" />

psake-project.ps1

@@ -44,7 +44,7 @@ Task Collect -Depends Merge -Description "Copy all artifacts to the build folder
     Collect-Localizations "Hangfire.Core" "net45"
     Collect-Localizations "Hangfire.Core" "netstandard1.3"
 
-    Collect-File "LICENSE"
+    Collect-File "LICENSE.md"
     Collect-File "NOTICES"
     Collect-File "COPYING.LESSER"
     Collect-File "COPYING"

src/Hangfire.Core/Common/CancellationTokenExtentions.cs

@@ -0,0 +1,83 @@
+// This file is part of Hangfire.
+// Copyright © 2018 Sergey Odinokov.
+// 
+// Hangfire is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as 
+// published by the Free Software Foundation, either version 3 
+// of the License, or any later version.
+// 
+// Hangfire is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Lesser General Public License for more details.
+// 
+// You should have received a copy of the GNU Lesser General Public 
+// License along with Hangfire. If not, see <http://www.gnu.org/licenses/>.
+
+using System;
+using System.Threading;
+
+namespace Hangfire.Common
+{
+    public static class CancellationTokenExtentions
+    {
+        /// <summary>
+        /// Returns a class that contains a <see cref="EventWaitHandle"/> that is set, when
+        /// the given <paramref name="cancellationToken"/> is canceled. This method is based
+        /// on cancellation token registration and avoids using the <see cref="CancellationToken.WaitHandle"/>
+        /// property as it may lead to high CPU issues.
+        /// </summary>
+        public static CancellationEvent GetCancellationEvent(this CancellationToken cancellationToken)
+        {
+            return new CancellationEvent(cancellationToken);
+        }
+
+        /// <summary>
+        /// Performs a wait until the specified <paramref name="timeout"/> is elapsed or the
+        /// given cancellation token is canceled. The wait is performed on a dedicated event
+        /// wait handle to avoid using the <see cref="CancellationToken.WaitHandle"/> property
+        /// that may lead to high CPU issues.
+        /// </summary>
+        public static bool Wait(this CancellationToken cancellationToken, TimeSpan timeout)
+        {
+            using (var cancellationEvent = GetCancellationEvent(cancellationToken))
+            {
+                return cancellationEvent.WaitHandle.WaitOne(timeout);
+            }
+        }
+
+        public class CancellationEvent : IDisposable
+        {
+            private readonly ManualResetEvent _mre;
+            private CancellationTokenRegistration _registration;
+
+            public CancellationEvent(CancellationToken cancellationToken)
+            {
+                _mre = new ManualResetEvent(false);
+                _registration = cancellationToken.Register(SetEvent, _mre);
+            }
+
+            public EventWaitHandle WaitHandle => _mre;
+
+            public void Dispose()
+            {
+                _registration.Dispose();
+                _mre.Dispose();
+            }
+
+            private static void SetEvent(object state)
+            {
+                try
+                {
+                    ((ManualResetEvent)state).Set();
+                }
+                catch (ObjectDisposedException)
+                {
+                    // When our event instance is already disposed, we already
+                    // aren't interested in any notifications. This statement
+                    // is just to ensure we don't throw any exceptions.
+                }
+            }
+        }
+    }
+}

src/Hangfire.Core/Hangfire.Core.NetStandard.csproj

@@ -75,6 +75,7 @@
     <Compile Include="Client\IClientExceptionFilter.cs" />
     <Compile Include="Client\IClientFilter.cs" />
     <Compile Include="Common\CachedExpressionCompiler.cs" />
+    <Compile Include="Common\CancellationTokenExtentions.cs" />
     <Compile Include="Common\ExpressionUtil\BinaryExpressionFingerprint.cs" />
     <Compile Include="Common\ExpressionUtil\CachedExpressionCompiler.cs" />
     <Compile Include="Common\ExpressionUtil\ConditionalExpressionFingerprint.cs" />

src/Hangfire.Core/Hangfire.Core.csproj

@@ -78,6 +78,7 @@
     <Compile Include="BackgroundJobServer.cs" />
     <Compile Include="BackgroundJobServerOptions.cs" />
     <Compile Include="Client\CoreBackgroundJobFactory.cs" />
+    <Compile Include="Common\CancellationTokenExtentions.cs" />
     <Compile Include="Common\MethodInfoExtensions.cs" />
     <Compile Include="Dashboard\Content\resx\Strings.Designer.cs">
       <AutoGen>True</AutoGen>

src/Hangfire.Core/Server/BackgroundProcessContext.cs

@@ -18,6 +18,7 @@
 using System.Collections.Generic;
 using System.Threading;
 using Hangfire.Annotations;
+using Hangfire.Common;
 
 namespace Hangfire.Server
 {
@@ -54,7 +55,7 @@ public BackgroundProcessContext(
 
         public void Wait(TimeSpan timeout)
         {
-            CancellationToken.WaitHandle.WaitOne(timeout);
+            CancellationToken.Wait(timeout);
         }
     }
 }

src/Hangfire.Core/Server/EveryMinuteThrottler.cs

@@ -16,6 +16,7 @@
 
 using System;
 using System.Threading;
+using Hangfire.Common;
 
 namespace Hangfire.Server
 {
@@ -36,7 +37,7 @@ public void Delay(CancellationToken token)
 
         private static void WaitASecondOrThrowIfCanceled(CancellationToken token)
         {
-            token.WaitHandle.WaitOne(TimeSpan.FromSeconds(1));
+            token.Wait(TimeSpan.FromSeconds(1));
             token.ThrowIfCancellationRequested();
         }
     }

src/Hangfire.SqlServer/CountersAggregator.cs

@@ -17,6 +17,7 @@
 using System;
 using System.Threading;
 using Dapper;
+using Hangfire.Common;
 using Hangfire.Logging;
 using Hangfire.Server;
 
@@ -63,15 +64,15 @@ public void Execute(CancellationToken cancellationToken)
 
                 if (removedCount >= NumberOfRecordsInSinglePass)
                 {
-                    cancellationToken.WaitHandle.WaitOne(DelayBetweenPasses);
+                    cancellationToken.Wait(DelayBetweenPasses);
                     cancellationToken.ThrowIfCancellationRequested();
                 }
                 // ReSharper disable once LoopVariableIsNeverChangedInsideLoop
             } while (removedCount >= NumberOfRecordsInSinglePass);
 
             Logger.Trace("Records from the 'Counter' table aggregated.");
 
-            cancellationToken.WaitHandle.WaitOne(_interval);
+            cancellationToken.Wait(_interval);
         }
 
         public override string ToString()

src/Hangfire.SqlServer/ExpirationManager.cs

@@ -18,6 +18,7 @@
 using System.Data.Common;
 using System.Data.SqlClient;
 using System.Threading;
+using Hangfire.Common;
 using Hangfire.Logging;
 using Hangfire.Server;
 using Hangfire.Storage;
@@ -85,7 +86,7 @@ public void Execute(CancellationToken cancellationToken)
                 Logger.Trace($"Outdated records removed from the '{table}' table.");
             }
 
-            cancellationToken.WaitHandle.WaitOne(_checkInterval);
+            cancellationToken.Wait(_checkInterval);
         }
 
         public override string ToString()

src/Hangfire.SqlServer/SqlServerJobQueue.cs

@@ -22,6 +22,7 @@
 using System.Threading;
 using Dapper;
 using Hangfire.Annotations;
+using Hangfire.Common;
 using Hangfire.Storage;
 
 // ReSharper disable RedundantAnonymousTypePropertyName
@@ -95,31 +96,34 @@ update top (1) JQ
 where Queue in @queues and
 (FetchedAt is null or FetchedAt < DATEADD(second, @timeout, GETUTCDATE()))";
 
-            do
+            using (var cancellationEvent = cancellationToken.GetCancellationEvent())
             {
-                cancellationToken.ThrowIfCancellationRequested();
-
-                _storage.UseConnection(null, connection =>
+                do
                 {
-                    fetchedJob = connection
-                        .Query<FetchedJob>(
-                            fetchJobSqlTemplate,
-                            new { queues = queues, timeout = _options.SlidingInvisibilityTimeout.Value.Negate().TotalSeconds })
-                        .SingleOrDefault();
-                });
+                    cancellationToken.ThrowIfCancellationRequested();
 
-                if (fetchedJob != null)
-                {
-                    return new SqlServerTimeoutJob(
-                        _storage,
-                        fetchedJob.Id,
-                        fetchedJob.JobId.ToString(CultureInfo.InvariantCulture),
-                        fetchedJob.Queue);
-                }
-
-                WaitHandle.WaitAny(new[] { cancellationToken.WaitHandle, NewItemInQueueEvent }, _options.QueuePollInterval);
-                cancellationToken.ThrowIfCancellationRequested();
-            } while (true);
+                    _storage.UseConnection(null, connection =>
+                    {
+                        fetchedJob = connection
+                            .Query<FetchedJob>(
+                                fetchJobSqlTemplate,
+                                new { queues = queues, timeout = _options.SlidingInvisibilityTimeout.Value.Negate().TotalSeconds })
+                            .SingleOrDefault();
+                    });
+
+                    if (fetchedJob != null)
+                    {
+                        return new SqlServerTimeoutJob(
+                            _storage,
+                            fetchedJob.Id,
+                            fetchedJob.JobId.ToString(CultureInfo.InvariantCulture),
+                            fetchedJob.Queue);
+                    }
+
+                    WaitHandle.WaitAny(new WaitHandle[] { cancellationEvent.WaitHandle, NewItemInQueueEvent }, _options.QueuePollInterval);
+                    cancellationToken.ThrowIfCancellationRequested();
+                } while (true);
+            }
         }
 
         private SqlServerTransactionJob DequeueUsingTransaction(string[] queues, CancellationToken cancellationToken)
@@ -133,47 +137,50 @@ private SqlServerTransactionJob DequeueUsingTransaction(string[] queues, Cancell
 from [{_storage.SchemaName}].JobQueue JQ with (readpast, updlock, rowlock, forceseek)
 where Queue in @queues and (FetchedAt is null or FetchedAt < DATEADD(second, @timeout, GETUTCDATE()))";
 
-            do
+            using (var cancellationEvent = cancellationToken.GetCancellationEvent())
             {
-                cancellationToken.ThrowIfCancellationRequested();
-                var connection = _storage.CreateAndOpenConnection();
-
-                try
+                do
                 {
-                    transaction = connection.BeginTransaction(IsolationLevel.ReadCommitted);
+                    cancellationToken.ThrowIfCancellationRequested();
+                    var connection = _storage.CreateAndOpenConnection();
+
+                    try
+                    {
+                        transaction = connection.BeginTransaction(IsolationLevel.ReadCommitted);
 
-                    fetchedJob = connection.Query<FetchedJob>(
-                        fetchJobSqlTemplate,
+                        fetchedJob = connection.Query<FetchedJob>(
+                            fetchJobSqlTemplate,
 #pragma warning disable 618
                         new { queues = queues, timeout = _options.InvisibilityTimeout.Negate().TotalSeconds },
 #pragma warning restore 618
                         transaction,
-                        commandTimeout: _storage.CommandTimeout).SingleOrDefault();
-
-                    if (fetchedJob != null)
-                    {
-                        return new SqlServerTransactionJob(
-                            _storage,
-                            connection,
-                            transaction,
-                            fetchedJob.JobId.ToString(CultureInfo.InvariantCulture),
-                            fetchedJob.Queue);
+                            commandTimeout: _storage.CommandTimeout).SingleOrDefault();
+
+                        if (fetchedJob != null)
+                        {
+                            return new SqlServerTransactionJob(
+                                _storage,
+                                connection,
+                                transaction,
+                                fetchedJob.JobId.ToString(CultureInfo.InvariantCulture),
+                                fetchedJob.Queue);
+                        }
                     }
-                }
-                finally
-                {
-                    if (fetchedJob == null)
+                    finally
                     {
-                        transaction?.Dispose();
-                        transaction = null;
+                        if (fetchedJob == null)
+                        {
+                            transaction?.Dispose();
+                            transaction = null;
 
-                        _storage.ReleaseConnection(connection);
+                            _storage.ReleaseConnection(connection);
+                        }
                     }
-                }
 
-                WaitHandle.WaitAny(new[] { cancellationToken.WaitHandle, NewItemInQueueEvent }, _options.QueuePollInterval);
-                cancellationToken.ThrowIfCancellationRequested();
-            } while (true);
+                    WaitHandle.WaitAny(new WaitHandle[] { cancellationEvent.WaitHandle, NewItemInQueueEvent }, _options.QueuePollInterval);
+                    cancellationToken.ThrowIfCancellationRequested();
+                } while (true);
+            }
         }
 
         [UsedImplicitly(ImplicitUseTargetFlags.WithMembers)]