From 040ea2e6b45b5909abe3c3b0e199ff6dd6136026 Mon Sep 17 00:00:00 2001
From: Stephen Halter <halter73@gmail.com>
Date: Thu, 18 Jan 2018 15:53:46 -0800
Subject: [PATCH] Fix MockLibuv.OnPostTask (#2260)

Prevents UvWriteReq leaks in LibuvOutputConsumerTests
---
 .../TestHelpers/MockLibuv.cs                  | 52 +++++--------------
 1 file changed, 14 insertions(+), 38 deletions(-)

diff --git a/test/Kestrel.Transport.Libuv.Tests/TestHelpers/MockLibuv.cs b/test/Kestrel.Transport.Libuv.Tests/TestHelpers/MockLibuv.cs
index 4f334bcfea..6cb3f6917a 100644
--- a/test/Kestrel.Transport.Libuv.Tests/TestHelpers/MockLibuv.cs
+++ b/test/Kestrel.Transport.Libuv.Tests/TestHelpers/MockLibuv.cs
@@ -16,7 +16,6 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Transport.Libuv.Tests.TestHelpers
         private readonly object _postLock = new object();
         private TaskCompletionSource<object> _onPostTcs = new TaskCompletionSource<object>();
         private bool _completedOnPostTcs;
-        private bool _sendCalled;
 
         private bool _stopLoop;
         private readonly ManualResetEventSlim _loopWh = new ManualResetEventSlim();
@@ -38,29 +37,17 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Transport.Libuv.Tests.TestHelpers
 
             _uv_async_send = postHandle =>
             {
-                // Attempt to run the async send logic inline; this should succeed most of the time.
-                // In the rare cases where it fails to acquire the lock, use Task.Run() so this call
-                // never blocks, since the real libuv never blocks.
-                if (Monitor.TryEnter(_postLock))
+                lock (_postLock)
                 {
-                    try
+                    if (_completedOnPostTcs)
                     {
-                        UvAsyncSend();
+                        _onPostTcs = new TaskCompletionSource<object>();
+                        _completedOnPostTcs = false;
                     }
-                    finally
-                    {
-                        Monitor.Exit(_postLock);
-                    }
-                }
-                else
-                {
-                    Task.Run(() =>
-                    {
-                        lock (_postLock)
-                        {
-                            UvAsyncSend();
-                        }
-                    });
+
+                    PostCount++;
+
+                    _loopWh.Set();
                 }
 
                 return 0;
@@ -83,13 +70,16 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Transport.Libuv.Tests.TestHelpers
 
                     lock (_postLock)
                     {
-                        _sendCalled = false;
                         _loopWh.Reset();
-                        _onPost(_postHandle.InternalGetHandle());
+                    }
 
+                    _onPost(_postHandle.InternalGetHandle());
+
+                    lock (_postLock)
+                    {
                         // Allow the loop to be run again before completing
                         // _onPostTcs given a nested uv_async_send call.
-                        if (!_sendCalled)
+                        if (!_loopWh.IsSet)
                         {
                             // Ensure any subsequent calls to uv_async_send
                             // create a new _onPostTcs to be completed.
@@ -171,19 +161,5 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Transport.Libuv.Tests.TestHelpers
         {
             return OnWrite(handle, nbufs, status => cb(req.InternalGetHandle(), status));
         }
-
-        private void UvAsyncSend()
-        {
-            if (_completedOnPostTcs)
-            {
-                _onPostTcs = new TaskCompletionSource<object>();
-                _completedOnPostTcs = false;
-            }
-
-            PostCount++;
-
-            _sendCalled = true;
-            _loopWh.Set();
-        }
     }
 }