Accurate timespan if the stopwatch is high resolution (#1230)

* Accurate timespan if the stopwatch is high resolution

* Made helper class internal instead of public

src/StackExchange.Redis/Profiling/ProfiledCommand.cs

@@ -19,15 +19,15 @@ internal sealed class ProfiledCommand : IProfiledCommand
 
         public DateTime CommandCreated => MessageCreatedDateTime;
 
-        public TimeSpan CreationToEnqueued => TimeSpan.FromTicks(EnqueuedTimeStamp - MessageCreatedTimeStamp);
+        public TimeSpan CreationToEnqueued => TimeSpanHelper.FromStopwatchTicks(EnqueuedTimeStamp - MessageCreatedTimeStamp);
 
-        public TimeSpan EnqueuedToSending => TimeSpan.FromTicks(RequestSentTimeStamp - EnqueuedTimeStamp);
+        public TimeSpan EnqueuedToSending => TimeSpanHelper.FromStopwatchTicks(RequestSentTimeStamp - EnqueuedTimeStamp);
 
-        public TimeSpan SentToResponse => TimeSpan.FromTicks(ResponseReceivedTimeStamp - RequestSentTimeStamp);
+        public TimeSpan SentToResponse => TimeSpanHelper.FromStopwatchTicks(ResponseReceivedTimeStamp - RequestSentTimeStamp);
 
-        public TimeSpan ResponseToCompletion => TimeSpan.FromTicks(CompletedTimeStamp - ResponseReceivedTimeStamp);
+        public TimeSpan ResponseToCompletion => TimeSpanHelper.FromStopwatchTicks(CompletedTimeStamp - ResponseReceivedTimeStamp);
 
-        public TimeSpan ElapsedTime => TimeSpan.FromTicks(CompletedTimeStamp - MessageCreatedTimeStamp);
+        public TimeSpan ElapsedTime => TimeSpanHelper.FromStopwatchTicks(CompletedTimeStamp - MessageCreatedTimeStamp);
 
         public IProfiledCommand RetransmissionOf => OriginalProfiling;
 

src/StackExchange.Redis/Profiling/TimeSpanHelper.cs

+using System;
+using System.Diagnostics;
+
+namespace StackExchange.Redis.Profiling
+{
+    /// <summary>
+    /// A helper class for dealing with Low/High Resolution Stopwatches and their ticks
+    /// </summary>
+    internal static class TimeSpanHelper
+    {
+        /// <summary>
+        /// Used to construct a timespan from ticks obtained using Stopwatch.GetTimestamp()
+        /// </summary>
+        /// <param name="ticks"></param>
+        /// <returns>A TimeSpan constructed from the ticks</returns>
+        internal static TimeSpan FromStopwatchTicks(long ticks)
+        {
+            return Stopwatch.IsHighResolution ? TimeSpan.FromMilliseconds(ticks / ((double) Stopwatch.Frequency / 1000)) : TimeSpan.FromTicks(ticks);
+        }
+    }
+}