Fix for ratelimiting possibly creating negative waits

CryptoExchange.Net/RateLimiting/Trackers/DecayWindowTracker.cs

@@ -80,7 +80,10 @@ namespace CryptoExchange.Net.RateLimiting.Trackers
         private TimeSpan DetermineWaitTime(int requestWeight)
         {
             var weightToRemove = Math.Max(Current - (Limit - requestWeight), 0);
-            return TimeSpan.FromMilliseconds(Math.Ceiling(weightToRemove / DecreaseRate) * TimePeriod.TotalMilliseconds);
+            var result = TimeSpan.FromMilliseconds(Math.Ceiling(weightToRemove / DecreaseRate) * TimePeriod.TotalMilliseconds);
+            if (result < TimeSpan.Zero)
+                return TimeSpan.Zero;
+            return result;
         }
     }
 }

CryptoExchange.Net/RateLimiting/Trackers/FixedAfterStartWindowTracker.cs

@@ -97,7 +97,10 @@ namespace CryptoExchange.Net.RateLimiting.Trackers
         private TimeSpan DetermineWaitTime()
         {
             var checkTime = DateTime.UtcNow;
-            return (_nextReset!.Value - checkTime) + _fixedWindowBuffer;
+            var result = (_nextReset!.Value - checkTime) + _fixedWindowBuffer;
+            if (result < TimeSpan.Zero)
+                return TimeSpan.Zero;
+            return result;
         }
     }
 }

CryptoExchange.Net/RateLimiting/Trackers/FixedWindowTracker.cs

@@ -93,7 +93,10 @@ namespace CryptoExchange.Net.RateLimiting.Trackers
             var checkTime = DateTime.UtcNow;
             var startCurrentWindow = checkTime.AddTicks(-(checkTime.Ticks % TimePeriod.Ticks));
             var wait = startCurrentWindow.Add(TimePeriod) - checkTime;
-            return wait.Add(_fixedWindowBuffer);
+            var result = wait.Add(_fixedWindowBuffer);
+            if (result < TimeSpan.Zero)
+                return TimeSpan.Zero;
+            return result;
         }
     }
 }

CryptoExchange.Net/RateLimiting/Trackers/SlidingWindowTracker.cs

@@ -16,6 +16,11 @@ namespace CryptoExchange.Net.RateLimiting.Trackers
         private readonly List<LimitEntry> _entries;
         private int _currentWeight = 0;
 
+        /// <summary>
+        /// Additional wait time to apply to account for fluctuating request times
+        /// </summary>
+        private static readonly TimeSpan _slidingWindowBuffer = TimeSpan.FromMilliseconds(1000);
+
         public SlidingWindowTracker(int limit, TimeSpan period)
         {
             Limit = limit;
@@ -89,7 +94,10 @@ namespace CryptoExchange.Net.RateLimiting.Trackers
                 removedWeight += entry.Weight;
                 if (removedWeight >= weightToRemove)
                 {
-                    return entry.Timestamp + TimePeriod - DateTime.UtcNow;
+                    var result = entry.Timestamp + TimePeriod + _slidingWindowBuffer - DateTime.UtcNow;
+                    if (result < TimeSpan.Zero)
+                        return TimeSpan.Zero;
+                    return result;
                 }
             }
 

CryptoExchange.Net/Testing/Comparers/JsonNetComparer.cs

@@ -80,6 +80,10 @@ namespace CryptoExchange.Net.Testing.Comparers
                         else if (jObj.Type == JTokenType.Array)
                         {
                             var resultObj = enumerator.Current;
+                            if (resultObj is string)
+                                // string list
+                                continue;
+
                             var resultProps = resultObj.GetType().GetProperties().Select(p => (p, p.GetCustomAttributes(typeof(ArrayPropertyAttribute), true).Cast<ArrayPropertyAttribute>().SingleOrDefault()));
                             var arrayConverterProperty = resultObj.GetType().GetCustomAttributes(typeof(JsonConverterAttribute), true).FirstOrDefault();
                             var jsonConverter = ((JsonConverterAttribute)arrayConverterProperty!).ConverterType;

CryptoExchange.Net/Testing/Comparers/SystemTextJsonComparer.cs

@@ -82,6 +82,10 @@ namespace CryptoExchange.Net.Testing.Comparers
                     else if (jObj.Type == JTokenType.Array)
                     {
                         var resultObj = enumerator.Current;
+                        if (resultObj is string)
+                            // string list
+                            continue;
+
                         var resultProps = resultObj.GetType().GetProperties().Select(p => (p, p.GetCustomAttributes(typeof(ArrayPropertyAttribute), true).Cast<ArrayPropertyAttribute>().SingleOrDefault()));
                         var arrayConverterProperty = resultObj.GetType().GetCustomAttributes(typeof(JsonConverterAttribute), true).FirstOrDefault();
                         var jsonConverter = ((JsonConverterAttribute)arrayConverterProperty!).ConverterType;