Fix: CircularTimeBuffer/TimeSlotResult was enforcing an incorrect inv…

…ariant.
imazen · Sep 13, 2017 · ab91afb · ab91afb
1 parent 3200cb7
commit ab91afb
Show file tree

Hide file tree

Showing 3 changed files with 29 additions and 19 deletions.
diff --git a/Core/Configuration/Performance/Support/RateTracking/CircularTimeBuffer.cs b/Core/Configuration/Performance/Support/RateTracking/CircularTimeBuffer.cs
@@ -58,7 +58,10 @@ void DequeueBuckets(long newHead)
                     var virtualDequeueCount = (toBucketIndexExclusive - fromBucketIndex);
                     var localDequeueCount = Math.Min(virtualDequeueCount,buckets);
                     Utilities.InterlockedMax(ref skippedResults, 0);
-                    Interlocked.Add(ref skippedResults, virtualDequeueCount - localDequeueCount);
+                    if (virtualDequeueCount > localDequeueCount)
+                    {
+                        Interlocked.Add(ref skippedResults, virtualDequeueCount - localDequeueCount);
+                    }
                     for (int toDeque = 0; toDeque < localDequeueCount; toDeque++)
                     {
                         var bucketIndex = fromBucketIndex + toDeque;
@@ -105,7 +108,7 @@ public IEnumerable<long> DequeueValues()
         {
             var enumerableResults = DequeueResults();
             // ReSharper disable once PossibleUnintendedReferenceComparison
-            return enumerableResults == Enumerable.Empty<TimeSlotResult>() ? Enumerable.Empty<long>() : enumerableResults.Select(r => r.Value.Value);
+            return enumerableResults == Enumerable.Empty<TimeSlotResult>() ? Enumerable.Empty<long>() : enumerableResults.Select(r => r.Value);
         }
 
         public override string ToString()
@@ -116,6 +119,8 @@ public override string ToString()
 
         public bool Record(long ticks, long count)
         {
+            if (ticks < 0) return false;
+
             var newIndex = (ticks / ticksPerBucket);
 
             Utilities.InterlockedMin(ref initialTail, newIndex);

diff --git a/Core/Configuration/Performance/Support/RateTracking/TimeSlotResult.cs b/Core/Configuration/Performance/Support/RateTracking/TimeSlotResult.cs
@@ -12,30 +12,19 @@ struct TimeSlotResult
     {
         public TimeSlotResult(long result, long slotBeginTicks)
         {
-            this.value = result;
-            this.SlotBeginTicks = slotBeginTicks;
+            Value = result;
+            SlotBeginTicks = slotBeginTicks;
         }
 
-        public long SlotBeginTicks { get; }
-
-        readonly long value;
-        public long? Value => SlotBeginTicks > 0 ? value : (long?)null;
 
-        public bool IsEmpty => SlotBeginTicks == 0;
-
-        /// <summary>
-        /// Empty does not denote a result of any kind; this is like null. 
-        /// </summary>
-        public static readonly TimeSlotResult Empty = new TimeSlotResult();
+        public long SlotBeginTicks { get; }
+        public long Value { get; }
 
-        /// <summary>
+            /// <summary>
         /// A zero result is a value of zero, not to be confused with Empty
         /// </summary>
         public static readonly TimeSlotResult ResultZero = new TimeSlotResult(0, 1);
 
-        public override string ToString()
-        {
-            return IsEmpty ? "(empty)" : $"[{value}] at {SlotBeginTicks}";
-        }
+        public override string ToString() =>  $"[{Value}] at {SlotBeginTicks}";
     }
 }
diff --git a/Tests/ImageResizer.Plugins.LicenseVerifier.Tests/DataStructureTests.cs b/Tests/ImageResizer.Plugins.LicenseVerifier.Tests/DataStructureTests.cs
@@ -74,6 +74,22 @@ public void CircularBufferTest()
             Assert.Equal(23, results.Count());
             Assert.Equal(new[] {0L, 1, 2, 3}, results.Take(4));
         }
+
+        [Fact]
+        public void MultiIntervalTest()
+        {
+            NamedInterval[] Intervals  = {
+                new NamedInterval { Unit = "second", Name = "Per Second", TicksDuration = Stopwatch.Frequency },
+                    new NamedInterval { Unit = "minute", Name = "Per Minute", TicksDuration = Stopwatch.Frequency * 60 },
+                    new NamedInterval { Unit = "15_mins", Name = "Per 15 Minutes", TicksDuration = Stopwatch.Frequency * 60 * 15 },
+                    new NamedInterval { Unit = "hour", Name = "Per Hour", TicksDuration = Stopwatch.Frequency * 60 * 60 },
+                };
+            var s = new MultiIntervalStats(Intervals);
+            for (long i = Stopwatch.Frequency * -1000; i < Stopwatch.Frequency * 5000; i += Stopwatch.Frequency / 2)
+            {
+                s.Record(i, 1);
+            }
+        }
 
         [Fact]
         public void TestAddMulModHash()