Don't block task queue for queued update task when long running tasks queued

Fixes #2935

Co-Authored-By: Mark McDowall <markus101@users.noreply.github.com>

src/NzbDrone.Core.Test/Messaging/Commands/CommandQueueFixture.cs

@@ -3,6 +3,7 @@ using FluentAssertions;
 using NUnit.Framework;
 using NzbDrone.Core.Download;
 using NzbDrone.Core.ImportLists;
+using NzbDrone.Core.Indexers;
 using NzbDrone.Core.Messaging.Commands;
 using NzbDrone.Core.Music.Commands;
 using NzbDrone.Core.Test.Framework;
@@ -25,6 +26,18 @@ namespace NzbDrone.Core.Test.Messaging.Commands
             Subject.Add(commandModel);
         }
 
+        private void GivenLongRunningCommand()
+        {
+            var commandModel = Builder<CommandModel>
+                .CreateNew()
+                .With(c => c.Name = "RssSync")
+                .With(c => c.Body = new RssSyncCommand())
+                .With(c => c.Status = CommandStatus.Started)
+                .Build();
+
+            Subject.Add(commandModel);
+        }
+
         private void GivenStartedTypeExclusiveCommand()
         {
             var commandModel = Builder<CommandModel>
@@ -85,6 +98,24 @@ namespace NzbDrone.Core.Test.Messaging.Commands
             command.Should().BeNull();
         }
 
+        [Test]
+        public void should_not_return_exclusive_command_if_long_running_command_running()
+        {
+            GivenLongRunningCommand();
+
+            var newCommandModel = Builder<CommandModel>
+                .CreateNew()
+                .With(c => c.Name = "ApplicationUpdate")
+                .With(c => c.Body = new ApplicationUpdateCommand())
+                .Build();
+
+            Subject.Add(newCommandModel);
+
+            Subject.TryGet(out var command);
+
+            command.Should().BeNull();
+        }
+
         [Test]
         public void should_not_return_type_exclusive_command_if_another_and_disk_access_command_running()
         {

src/NzbDrone.Core/Download/ProcessMonitoredDownloadsCommand.cs

@@ -5,5 +5,7 @@ namespace NzbDrone.Core.Download
     public class ProcessMonitoredDownloadsCommand : Command
     {
         public override bool RequiresDiskAccess => true;
+
+        public override bool IsLongRunning => true;
     }
 }

src/NzbDrone.Core/Indexers/RssSyncCommand.cs

@@ -5,5 +5,7 @@ namespace NzbDrone.Core.Indexers
     public class RssSyncCommand : Command
     {
         public override bool SendUpdatesToClient => true;
+
+        public override bool IsLongRunning => true;
     }
 }

src/NzbDrone.Core/Messaging/Commands/Command.cs

@@ -26,8 +26,8 @@ namespace NzbDrone.Core.Messaging.Commands
         public virtual string CompletionMessage => "Completed";
         public virtual bool RequiresDiskAccess => false;
         public virtual bool IsExclusive => false;
-
         public virtual bool IsTypeExclusive => false;
+        public virtual bool IsLongRunning => false;
 
         public string Name { get; private set; }
         public DateTime? LastExecutionTime { get; set; }

src/NzbDrone.Core/Messaging/Commands/CommandQueue.cs

@@ -176,6 +176,11 @@ namespace NzbDrone.Core.Messaging.Commands
                         queuedCommands = queuedCommands.Where(c => !exclusiveTypes.Any(x => x == c.Body.Name));
                     }
 
+                    if (startedCommands.Any(x => x.Body.IsLongRunning))
+                    {
+                        queuedCommands = queuedCommands.Where(c => c.Status == CommandStatus.Queued && !c.Body.IsExclusive);
+                    }
+
                     var localItem = queuedCommands.OrderByDescending(c => c.Priority)
                                                   .ThenBy(c => c.QueuedAt)
                                                   .FirstOrDefault();