run whr at low priority

Author: DeinFreund

Shared/PlasmaShared/PriorityScheduler.cs

@@ -0,0 +1,64 @@
+using System;
+using System.Collections.Concurrent;
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace ZkData
+{
+    //Priority Scheduler implementation from https://stackoverflow.com/a/9056702/ by Roman Starkov
+    public class PriorityScheduler : TaskScheduler
+    {
+        public static PriorityScheduler AboveNormal = new PriorityScheduler(ThreadPriority.AboveNormal);
+        public static PriorityScheduler BelowNormal = new PriorityScheduler(ThreadPriority.BelowNormal);
+        public static PriorityScheduler Lowest = new PriorityScheduler(ThreadPriority.Lowest);
+
+        private BlockingCollection<Task> _tasks = new BlockingCollection<Task>();
+        private Thread[] _threads;
+        private ThreadPriority _priority;
+        private readonly int _maximumConcurrencyLevel = Math.Max(1, Environment.ProcessorCount);
+
+        public PriorityScheduler(ThreadPriority priority)
+        {
+            _priority = priority;
+        }
+
+        public override int MaximumConcurrencyLevel
+        {
+            get { return _maximumConcurrencyLevel; }
+        }
+
+        protected override IEnumerable<Task> GetScheduledTasks()
+        {
+            return _tasks;
+        }
+
+        protected override void QueueTask(Task task)
+        {
+            _tasks.Add(task);
+
+            if (_threads == null)
+            {
+                _threads = new Thread[_maximumConcurrencyLevel];
+                for (int i = 0; i < _threads.Length; i++)
+                {
+                    int local = i;
+                    _threads[i] = new Thread(() =>
+                    {
+                        foreach (Task t in _tasks.GetConsumingEnumerable())
+                            base.TryExecuteTask(t);
+                    });
+                    _threads[i].Name = string.Format("PriorityScheduler: ", i);
+                    _threads[i].Priority = _priority;
+                    _threads[i].IsBackground = true;
+                    _threads[i].Start();
+                }
+            }
+        }
+
+        protected override bool TryExecuteTaskInline(Task task, bool taskWasPreviouslyQueued)
+        {
+            return false; // we might not want to execute task that should schedule as high or low priority inline
+        }
+    }
+}

ZkData/Ef/WHR/WholeHistoryRating.cs

@@ -224,7 +224,7 @@ public void UpdateRatings()
                     {
                         Trace.TraceError("Thread error while updating WHR " + category +" " + ex);
                     }
-                });
+                }, CancellationToken.None, TaskCreationOptions.None, PriorityScheduler.BelowNormal);
                 lastUpdate = latestBattle;
             }