From f47cb47c4e02be6269320e5db98fc13be784263f Mon Sep 17 00:00:00 2001
From: "Eric J. Smith" <eric@codesmithtools.com>
Date: Sat, 31 Aug 2024 03:21:11 -0500
Subject: [PATCH] Try fixing queue metrics instrument again

---
 src/Foundatio/Queues/QueueBase.cs          |  2 +-
 src/Foundatio/Utility/InstrumentsValues.cs | 65 +++++++++++-----------
 2 files changed, 34 insertions(+), 33 deletions(-)

diff --git a/src/Foundatio/Queues/QueueBase.cs b/src/Foundatio/Queues/QueueBase.cs
index 2231b429..07f53e8f 100644
--- a/src/Foundatio/Queues/QueueBase.cs
+++ b/src/Foundatio/Queues/QueueBase.cs
@@ -69,7 +69,7 @@ protected QueueBase(TOptions options) : base(options?.TimeProvider, options?.Log
             {
                 return (0, 0, 0);
             }
-        });
+        }, _logger);
 
         _countGauge = FoundatioDiagnostics.Meter.CreateObservableGauge(GetFullMetricName("count"), () => new Measurement<long>(queueMetricValues.GetValue1()), description: "Number of items in the queue");
         _workingGauge = FoundatioDiagnostics.Meter.CreateObservableGauge(GetFullMetricName("working"), () => new Measurement<long>(queueMetricValues.GetValue2()), description: "Number of items currently being processed");
diff --git a/src/Foundatio/Utility/InstrumentsValues.cs b/src/Foundatio/Utility/InstrumentsValues.cs
index 922fb2ec..f9d9e128 100644
--- a/src/Foundatio/Utility/InstrumentsValues.cs
+++ b/src/Foundatio/Utility/InstrumentsValues.cs
@@ -1,4 +1,6 @@
 using System;
+using System.Threading;
+using Microsoft.Extensions.Logging;
 
 namespace Foundatio.Utility;
 
@@ -7,58 +9,57 @@ public class InstrumentsValues<T1, T2, T3>
                 where T2 : struct
                 where T3 : struct
 {
+    private readonly object _lock = new();
+    private int _readCount;
+    private bool _valuesUpdating;
+    private readonly AutoResetEvent _valuesUpdatingEvent = new(false);
     private T1? _value1;
     private T2? _value2;
     private T3? _value3;
-    private Func<(T1, T2, T3)> UpdateValues { get; set; }
+    private readonly Func<(T1, T2, T3)> _readValuesFunc;
+    private readonly ILogger _logger;
 
-    public InstrumentsValues(Func<(T1, T2, T3)> readValues)
+    public InstrumentsValues(Func<(T1, T2, T3)> readValuesFunc, ILogger logger)
     {
-        _value1 = null;
-        _value2 = null;
-        _value3 = null;
-
-        UpdateValues = readValues;
+        _readValuesFunc = readValuesFunc;
+        _logger = logger;
     }
 
-    public T1 GetValue1()
+    private void EnsureValues()
     {
-        if (!_value1.HasValue)
-            (_value1, _value2, _value3) = UpdateValues();
+        lock (_lock)
+        {
+            if (_readCount == 0) {
+                _logger.LogDebug("Getting values");
+                (_value1, _value2, _value3) = _readValuesFunc();
+            }
 
-        if (_value1 == null)
-            return default;
+            // get values every 3 reads
+            if (_readCount == 2)
+                _readCount = 0;
+            else
+                _readCount++;
+        }
+    }
 
-        T1 value = _value1.Value;
-        _value1 = null;
-        return value;
+    public T1 GetValue1()
+    {
+        EnsureValues();
 
+        return _value1 ?? default;
     }
 
     public T2 GetValue2()
     {
-        if (!_value2.HasValue)
-            (_value1, _value2, _value3) = UpdateValues();
-
-        if (_value2 == null)
-            return default;
-
-        T2 value = _value2.Value;
-        _value2 = null;
-        return value;
+        EnsureValues();
 
+        return _value2 ?? default;
     }
 
     public T3 GetValue3()
     {
-        if (!_value3.HasValue)
-            (_value1, _value2, _value3) = UpdateValues();
-
-        if (_value3 == null)
-            return default;
+        EnsureValues();
 
-        T3 value = _value3.Value;
-        _value3 = null;
-        return value;
+        return _value3 ?? default;
     }
 }