Replacing random elements in queue when overloaded

Author: bmermet

src/Datadog.Tracer.Tests/AgentWriterBufferTests.cs

@@ -34,11 +34,17 @@ public void Push_MoreThanCapacity_False()
 
             Assert.False(buffer.Push(101));
 
+            // Check that one random element of the queue was replaced
             var vals = buffer.Pop();
+            var replaced = 0;
             for(int i = 0; i <100; i++)
             {
-                Assert.Equal(i, vals[i]);
+                if(vals[i] != i)
+                {
+                    replaced++;
+                }
             }
+            Assert.Equal(1, replaced);
         }
 
     }

src/Datadog.Tracer/AgentWriterBuffer.cs

@@ -8,11 +8,13 @@ internal class AgentWriterBuffer<T>
         private readonly Object _lock = new Object();
         private readonly int _maxSize;
         private List<T> _items;
+        private Random _random;
 
         public AgentWriterBuffer(int maxSize)
         {
             _maxSize = maxSize;
             _items = new List<T>();
+            _random = new Random();
         }
 
         public bool Push(T item)
@@ -24,7 +26,11 @@ public bool Push(T item)
                     _items.Add(item);
                     return true;
                 }
-                return false;
+                else
+                {
+                    _items[_random.Next(_items.Count)] = item;
+                    return false;
+                }
             }
         }