[release/5.0] Fix Activity.Baggage items Order (#42712)

Co-authored-by: Tarek Mahmoud Sayed <tarekms@microsoft.com>

Author: github-actions[bot]

src/libraries/System.Diagnostics.DiagnosticSource/src/System/Diagnostics/Activity.cs

@@ -434,7 +434,7 @@ public Activity AddBaggage(string key, string? value)
 
             if (_baggage != null || Interlocked.CompareExchange(ref _baggage, new LinkedList<KeyValuePair<string, string?>>(kvp), null) != null)
             {
-                _baggage.Add(kvp);
+                _baggage.AddFront(kvp);
             }
 
             return this;
@@ -1288,13 +1288,24 @@ public void Add(T value)
             {
                 LinkedListNode<T> newNode = new LinkedListNode<T>(value);
 
-                lock (_first)
+                lock (this)
                 {
                     _last.Next = newNode;
                     _last = newNode;
                 }
             }
 
+            public void AddFront(T value)
+            {
+                LinkedListNode<T> newNode = new LinkedListNode<T>(value);
+
+                lock (this)
+                {
+                    newNode.Next = _first;
+                    _first = newNode;
+                }
+            }
+
             // Note: Some customers use this GetEnumerator dynamically to avoid allocations.
             public Enumerator<T> GetEnumerator() => new Enumerator<T>(_first);
             IEnumerator<T> IEnumerable<T>.GetEnumerator() => GetEnumerator();

src/libraries/System.Diagnostics.DiagnosticSource/tests/ActivityTests.cs

@@ -84,9 +84,9 @@ public void Baggage()
                     Assert.Equal("world", anotherActivity.GetBaggageItem("hello"));
                     Assert.Equal(4, anotherActivity.Baggage.Count());
                     Assert.Equal(new KeyValuePair<string, string>("hello", "world"), anotherActivity.Baggage.First());
-                    Assert.Equal(new KeyValuePair<string, string>(Key + 0, Value + 0), anotherActivity.Baggage.Skip(1).First());
+                    Assert.Equal(new KeyValuePair<string, string>(Key + 2, Value + 2), anotherActivity.Baggage.Skip(1).First());
                     Assert.Equal(new KeyValuePair<string, string>(Key + 1, Value + 1), anotherActivity.Baggage.Skip(2).First());
-                    Assert.Equal(new KeyValuePair<string, string>(Key + 2, Value + 2), anotherActivity.Baggage.Skip(3).First());
+                    Assert.Equal(new KeyValuePair<string, string>(Key + 0, Value + 0), anotherActivity.Baggage.Skip(3).First());
                 }
                 finally
                 {
@@ -99,6 +99,69 @@ public void Baggage()
             }
         }
 
+        [Fact]
+        public void TestBaggageOrderAndDuplicateKeys()
+        {
+            Activity a = new Activity("Baggage");
+            a.AddBaggage("1", "1");
+            a.AddBaggage("1", "2");
+            a.AddBaggage("1", "3");
+            a.AddBaggage("1", "4");
+
+            int value = 4;
+
+            foreach (KeyValuePair<string, string> kvp in a.Baggage)
+            {
+                Assert.Equal("1", kvp.Key);
+                Assert.Equal(value.ToString(), kvp.Value);
+                value--;
+            }
+
+            Assert.Equal("4", a.GetBaggageItem("1"));
+        }
+
+        [ConditionalFact(typeof(RemoteExecutor), nameof(RemoteExecutor.IsSupported))]
+        public void TestBaggageWithChainedActivities()
+        {
+            RemoteExecutor.Invoke(() => {
+                Activity a1 = new Activity("a1");
+                a1.Start();
+
+                a1.AddBaggage("1", "1");
+                a1.AddBaggage("2", "2");
+
+                IEnumerable<KeyValuePair<string, string>> baggages = a1.Baggage;
+                Assert.Equal(2, baggages.Count());
+                Assert.Equal(new KeyValuePair<string, string>("2", "2"), baggages.ElementAt(0));
+                Assert.Equal(new KeyValuePair<string, string>("1", "1"), baggages.ElementAt(1));
+
+                Activity a2 = new Activity("a2");
+                a2.Start();
+
+                a2.AddBaggage("3", "3");
+                baggages = a2.Baggage;
+                Assert.Equal(3, baggages.Count());
+                Assert.Equal(new KeyValuePair<string, string>("3", "3"), baggages.ElementAt(0));
+                Assert.Equal(new KeyValuePair<string, string>("2", "2"), baggages.ElementAt(1));
+                Assert.Equal(new KeyValuePair<string, string>("1", "1"), baggages.ElementAt(2));
+
+                Activity a3 = new Activity("a3");
+                a3.Start();
+
+                a3.AddBaggage("4", "4");
+                baggages = a3.Baggage;
+                Assert.Equal(4, baggages.Count());
+                Assert.Equal(new KeyValuePair<string, string>("4", "4"), baggages.ElementAt(0));
+                Assert.Equal(new KeyValuePair<string, string>("3", "3"), baggages.ElementAt(1));
+                Assert.Equal(new KeyValuePair<string, string>("2", "2"), baggages.ElementAt(2));
+                Assert.Equal(new KeyValuePair<string, string>("1", "1"), baggages.ElementAt(3));
+
+                a3.Dispose();
+                a2.Dispose();
+                a1.Dispose();
+            }).Dispose();
+        }
+
         /// <summary>
         /// Tests Tags operations
         /// </summary>