From 8366a4361706ffe0e063ec5353f6e9e78fcef6b4 Mon Sep 17 00:00:00 2001
From: xinchen <xinchen@microsoft.com>
Date: Fri, 8 Jun 2018 13:42:54 -0700
Subject: [PATCH] [#106] Unobserved exception was rethrown by the finalizer
 thread

---
 .../Amqp/FaultTolerantAmqpObject.cs           |  5 ++
 Microsoft.Azure.Amqp/Singleton.cs             | 51 ++++++++++---------
 2 files changed, 31 insertions(+), 25 deletions(-)

diff --git a/Microsoft.Azure.Amqp/Amqp/FaultTolerantAmqpObject.cs b/Microsoft.Azure.Amqp/Amqp/FaultTolerantAmqpObject.cs
index 39c678fe..b8562cab 100644
--- a/Microsoft.Azure.Amqp/Amqp/FaultTolerantAmqpObject.cs
+++ b/Microsoft.Azure.Amqp/Amqp/FaultTolerantAmqpObject.cs
@@ -41,6 +41,11 @@ public bool TryGetOpenedObject(out T openedAmqpObject)
             return openedAmqpObject != null;
         }
 
+        protected override bool IsValid(T value)
+        {
+            return value.State == AmqpObjectState.Opened;
+        }
+
         protected override async Task<T> OnCreateAsync(TimeSpan timeout)
         {
             T amqpObject = await this.createObjectAsync(timeout).ConfigureAwait(false);
diff --git a/Microsoft.Azure.Amqp/Singleton.cs b/Microsoft.Azure.Amqp/Singleton.cs
index 26e5dcf5..0c477ece 100644
--- a/Microsoft.Azure.Amqp/Singleton.cs
+++ b/Microsoft.Azure.Amqp/Singleton.cs
@@ -95,13 +95,30 @@ public async Task<TValue> GetOrCreateAsync(TimeSpan timeout)
 
                 if (this.TryGet(out tcs))
                 {
-                    return await tcs.Task.ConfigureAwait(false);
+                    TValue current = await tcs.Task.ConfigureAwait(false);
+                    if (this.IsValid(current))
+                    {
+                        return current;
+                    }
+
+                    this.Invalidate(current);
                 }
 
                 tcs = new TaskCompletionSource<TValue>();
                 if (this.TrySet(tcs))
                 {
-                    this.CreateValue(tcs, timeoutHelper.RemainingTime()).Fork();
+                    try
+                    {
+                        TValue value = await this.OnCreateAsync(timeout).ConfigureAwait(false);
+                        tcs.SetResult(value);
+                    }
+                    catch (Exception ex) when (!Fx.IsFatal(ex))
+                    {
+                        this.TryRemove();
+                        tcs.SetException(ex);
+                    }
+
+                    return await tcs.Task;
                 }
             }
 
@@ -109,10 +126,8 @@ public async Task<TValue> GetOrCreateAsync(TimeSpan timeout)
             {
                 throw new ObjectDisposedException(this.GetType().Name);
             }
-            else
-            {
-                throw new TimeoutException(string.Format(CultureInfo.InvariantCulture, "Timed out trying to create {0}", this.GetType().Name));
-            }
+
+            throw new TimeoutException(string.Format(CultureInfo.InvariantCulture, "Creation of {0} did not complete in {1} milliseconds.", typeof(TValue).Name, timeout.TotalMilliseconds));
         }
 
         protected void Invalidate(TValue instance)
@@ -128,6 +143,11 @@ protected void Invalidate(TValue instance)
             }
         }
 
+        protected virtual bool IsValid(TValue value)
+        {
+            return true;
+        }
+
         protected abstract Task<TValue> OnCreateAsync(TimeSpan timeout);
 
         protected abstract void OnSafeClose(TValue value);
@@ -169,24 +189,5 @@ bool TryRemove()
                 }
             }
         }
-
-        async Task CreateValue(TaskCompletionSource<TValue> tcs, TimeSpan timeout)
-        {
-            try
-            {
-                TValue value = await OnCreateAsync(timeout).ConfigureAwait(false);
-                tcs.SetResult(value);
-
-                if (this.disposed)
-                {
-                    OnSafeClose(value);
-                }
-            }
-            catch (Exception ex) when (!Fx.IsFatal(ex))
-            {
-                this.TryRemove();
-                tcs.SetException(ex);
-            }
-        }
     }
 }