WebServiceTarget - FlushAsync - Avoid premature flush

src/NLog/Internal/AsyncOperationCounter.cs

@@ -0,0 +1,142 @@
+// 
+// Copyright (c) 2004-2016 Jaroslaw Kowalski <jaak@jkowalski.net>, Kim Christensen, Julian Verdurmen
+// 
+// All rights reserved.
+// 
+// Redistribution and use in source and binary forms, with or without 
+// modification, are permitted provided that the following conditions 
+// are met:
+// 
+// * Redistributions of source code must retain the above copyright notice, 
+//   this list of conditions and the following disclaimer. 
+// 
+// * Redistributions in binary form must reproduce the above copyright notice,
+//   this list of conditions and the following disclaimer in the documentation
+//   and/or other materials provided with the distribution. 
+// 
+// * Neither the name of Jaroslaw Kowalski nor the names of its 
+//   contributors may be used to endorse or promote products derived from this
+//   software without specific prior written permission. 
+// 
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
+// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
+// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE 
+// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
+// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
+// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
+// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF 
+// THE POSSIBILITY OF SUCH DAMAGE.
+// 
+
+namespace NLog.Internal
+{
+    using System;
+    using System.Collections.Generic;
+    using NLog.Common;
+
+    /// <summary>
+    /// Keeps track of pending operation count, and can notify when pending operation count reaches zero
+    /// </summary>
+    internal class AsyncOperationCounter
+    {
+        private int _pendingOperationCounter;
+        private readonly LinkedList<AsyncContinuation> _pendingCompletionList = new LinkedList<AsyncContinuation>();
+
+        /// <summary>
+        /// Mark operation has started
+        /// </summary>
+        public void BeginOperation()
+        {
+            System.Threading.Interlocked.Increment(ref _pendingOperationCounter);
+        }
+
+        /// <summary>
+        /// Mark operation has completed
+        /// </summary>
+        /// <param name="exception">Exception coming from the completed operation [optional]</param>
+        public void CompleteOperation(Exception exception)
+        { 
+            if (_pendingCompletionList.Count > 0)
+            {
+                lock (_pendingCompletionList)
+                {
+                    System.Threading.Interlocked.Decrement(ref _pendingOperationCounter);
+                    var nodeNext = _pendingCompletionList.First;
+                    while (nodeNext != null)
+                    {
+                        var nodeValue = nodeNext.Value;
+                        nodeNext = nodeNext.Next;
+                        nodeValue(exception);  // Will modify _pendingCompletionList
+                    }
+                }
+            }
+            else
+            {
+                System.Threading.Interlocked.Decrement(ref _pendingOperationCounter);
+            }
+        }
+
+        /// <summary>
+        /// Registers an AsyncContinuation to be called when all pending operations have completed
+        /// </summary>
+        /// <param name="asyncContinuation">Invoked on completion</param>
+        /// <returns>AsyncContinuation operation</returns>
+        public AsyncContinuation RegisterCompletionNotification(AsyncContinuation asyncContinuation)
+        {
+            if (_pendingOperationCounter == 0)
+            {
+                return asyncContinuation;
+            }
+            else
+            {
+                lock (_pendingCompletionList)
+                {
+                    var pendingCompletion = new LinkedListNode<AsyncContinuation>(null);
+                    _pendingCompletionList.AddLast(pendingCompletion);
+
+                    // We only want to wait for the operations currently in progress (not the future operations)
+                    int remainingCompletionCounter = System.Threading.Interlocked.Increment(ref _pendingOperationCounter);
+                    if (remainingCompletionCounter <= 0)
+                    {
+                        System.Threading.Interlocked.Exchange(ref _pendingOperationCounter, 0);
+                        _pendingCompletionList.Remove(pendingCompletion);
+                        return asyncContinuation;
+                    }
+
+                    pendingCompletion.Value = (ex) =>
+                    {
+                        if (System.Threading.Interlocked.Decrement(ref remainingCompletionCounter) == 0)
+                        {
+                            lock (_pendingCompletionList)
+                            {
+                                System.Threading.Interlocked.Decrement(ref _pendingOperationCounter);
+                                _pendingCompletionList.Remove(pendingCompletion);
+                                var nodeNext = _pendingCompletionList.First;
+                                while (nodeNext != null)
+                                {
+                                    var nodeValue = nodeNext.Value;
+                                    nodeNext = nodeNext.Next;
+                                    nodeValue(ex);  // Will modify _pendingCompletionList
+                                }
+                            }
+                            asyncContinuation(ex);
+                        }
+                    };
+
+                    return pendingCompletion.Value;
+                }
+            }
+        }
+
+        /// <summary>
+        /// Clear o
+        /// </summary>
+        public void Clear()
+        {
+            _pendingCompletionList.Clear();
+        }
+    }
+}

src/NLog/NLog.Xamarin.Android.csproj

@@ -126,6 +126,7 @@
     <Compile Include="ILoggerBase-V1.cs" />
     <Compile Include="ILogger-V1.cs" />
     <Compile Include="Internal\ArrayHelper.cs" />
+    <Compile Include="Internal\AsyncOperationCounter.cs" />
     <Compile Include="Internal\ConfigurationManager.cs" />
     <Compile Include="Internal\DictionaryAdapter.cs" />
     <Compile Include="Internal\EncodingHelpers.cs" />

src/NLog/NLog.Xamarin.iOS.csproj

@@ -123,6 +123,7 @@
     <Compile Include="ILoggerBase-V1.cs" />
     <Compile Include="ILogger-V1.cs" />
     <Compile Include="Internal\ArrayHelper.cs" />
+    <Compile Include="Internal\AsyncOperationCounter.cs" />
     <Compile Include="Internal\ConfigurationManager.cs" />
     <Compile Include="Internal\DictionaryAdapter.cs" />
     <Compile Include="Internal\EncodingHelpers.cs" />

src/NLog/NLog.doc.csproj

@@ -136,6 +136,7 @@
     <Compile Include="ILoggerBase-V1.cs" />
     <Compile Include="ILogger-V1.cs" />
     <Compile Include="Internal\ArrayHelper.cs" />
+    <Compile Include="Internal\AsyncOperationCounter.cs" />
     <Compile Include="Internal\ConfigurationManager.cs" />
     <Compile Include="Internal\DictionaryAdapter.cs" />
     <Compile Include="Internal\EncodingHelpers.cs" />

src/NLog/NLog.mono.csproj

@@ -142,6 +142,7 @@
     <Compile Include="ILoggerBase-V1.cs" />
     <Compile Include="ILogger-V1.cs" />
     <Compile Include="Internal\ArrayHelper.cs" />
+    <Compile Include="Internal\AsyncOperationCounter.cs" />
     <Compile Include="Internal\ConfigurationManager.cs" />
     <Compile Include="Internal\DictionaryAdapter.cs" />
     <Compile Include="Internal\EncodingHelpers.cs" />

src/NLog/NLog.netfx35.csproj

@@ -136,6 +136,7 @@
     <Compile Include="ILoggerBase-V1.cs" />
     <Compile Include="ILogger-V1.cs" />
     <Compile Include="Internal\ArrayHelper.cs" />
+    <Compile Include="Internal\AsyncOperationCounter.cs" />
     <Compile Include="Internal\ConfigurationManager.cs" />
     <Compile Include="Internal\DictionaryAdapter.cs" />
     <Compile Include="Internal\EncodingHelpers.cs" />

src/NLog/NLog.netfx40.csproj

@@ -136,6 +136,7 @@
     <Compile Include="ILoggerBase-V1.cs" />
     <Compile Include="ILogger-V1.cs" />
     <Compile Include="Internal\ArrayHelper.cs" />
+    <Compile Include="Internal\AsyncOperationCounter.cs" />
     <Compile Include="Internal\ConfigurationManager.cs" />
     <Compile Include="Internal\DictionaryAdapter.cs" />
     <Compile Include="Internal\EncodingHelpers.cs" />

src/NLog/NLog.netfx45.csproj

@@ -142,6 +142,7 @@
     <Compile Include="ILoggerBase-V1.cs" />
     <Compile Include="ILogger-V1.cs" />
     <Compile Include="Internal\ArrayHelper.cs" />
+    <Compile Include="Internal\AsyncOperationCounter.cs" />
     <Compile Include="Internal\ConfigurationManager.cs" />
     <Compile Include="Internal\DictionaryAdapter.cs" />
     <Compile Include="Internal\EncodingHelpers.cs" />

src/NLog/NLog.sl4.csproj

@@ -143,6 +143,7 @@
     <Compile Include="ILoggerBase-V1.cs" />
     <Compile Include="ILogger-V1.cs" />
     <Compile Include="Internal\ArrayHelper.cs" />
+    <Compile Include="Internal\AsyncOperationCounter.cs" />
     <Compile Include="Internal\ConfigurationManager.cs" />
     <Compile Include="Internal\DictionaryAdapter.cs" />
     <Compile Include="Internal\EncodingHelpers.cs" />

src/NLog/NLog.sl5.csproj

@@ -140,6 +140,7 @@
     <Compile Include="ILoggerBase-V1.cs" />
     <Compile Include="ILogger-V1.cs" />
     <Compile Include="Internal\ArrayHelper.cs" />
+    <Compile Include="Internal\AsyncOperationCounter.cs" />
     <Compile Include="Internal\ConfigurationManager.cs" />
     <Compile Include="Internal\DictionaryAdapter.cs" />
     <Compile Include="Internal\EncodingHelpers.cs" />

src/NLog/NLog.wp7.csproj

@@ -139,6 +139,7 @@
     <Compile Include="ILoggerBase-V1.cs" />
     <Compile Include="ILogger-V1.cs" />
     <Compile Include="Internal\ArrayHelper.cs" />
+    <Compile Include="Internal\AsyncOperationCounter.cs" />
     <Compile Include="Internal\ConfigurationManager.cs" />
     <Compile Include="Internal\DictionaryAdapter.cs" />
     <Compile Include="Internal\EncodingHelpers.cs" />

src/NLog/NLog.wp71.csproj

@@ -139,6 +139,7 @@
     <Compile Include="ILoggerBase-V1.cs" />
     <Compile Include="ILogger-V1.cs" />
     <Compile Include="Internal\ArrayHelper.cs" />
+    <Compile Include="Internal\AsyncOperationCounter.cs" />
     <Compile Include="Internal\ConfigurationManager.cs" />
     <Compile Include="Internal\DictionaryAdapter.cs" />
     <Compile Include="Internal\EncodingHelpers.cs" />

src/NLog/NLog.wp8.csproj

@@ -164,6 +164,7 @@
     <Compile Include="ILoggerBase-V1.cs" />
     <Compile Include="ILogger-V1.cs" />
     <Compile Include="Internal\ArrayHelper.cs" />
+    <Compile Include="Internal\AsyncOperationCounter.cs" />
     <Compile Include="Internal\ConfigurationManager.cs" />
     <Compile Include="Internal\DictionaryAdapter.cs" />
     <Compile Include="Internal\EncodingHelpers.cs" />