FilteringTargetWrapper: Add support for batch writing + PostFilteringTargetWrapper: performance optimizations

src/NLog/Config/LoggingConfigurationParser.cs

@@ -1021,6 +1021,11 @@ private void SetPropertyFromElement(object o, ILoggingConfigurationElement eleme
                 return;
             }
 
+            if (SetFilterFromElement(o, propInfo, element))
+            {
+                return;
+            }
+
             SetItemFromElement(o, propInfo, element);
         }
 
@@ -1065,16 +1070,29 @@ private object ParseArrayItemFromElement(Type elementType, ILoggingConfiguration
             return arrayItem;
         }
 
-        private bool SetLayoutFromElement(object o, PropertyInfo propInfo, ILoggingConfigurationElement layoutElement)
+        private bool SetLayoutFromElement(object o, PropertyInfo propInfo, ILoggingConfigurationElement element)
         {
-            Layout layout = TryCreateLayoutInstance(layoutElement, propInfo.PropertyType);
+            var layout = TryCreateLayoutInstance(element, propInfo.PropertyType);
 
             // and is a Layout and 'type' attribute has been specified
             if (layout != null)
             {
-                ConfigureObjectFromAttributes(layout, layoutElement, true);
-                ConfigureObjectFromElement(layout, layoutElement);
-                propInfo.SetValue(o, layout, null);
+                SetItemOnProperty(o, propInfo, element, layout);
+                return true;
+            }
+
+            return false;
+        }
+
+        private bool SetFilterFromElement(object o, PropertyInfo propInfo, ILoggingConfigurationElement element)
+        {
+            var type = propInfo.PropertyType;
+
+            Filter filter = TryCreateFilterInstance(element, type);
+            // and is a Filter and 'type' attribute has been specified
+            if (filter != null)
+            {
+                SetItemOnProperty(o, propInfo, element, filter);
                 return true;
             }
 
@@ -1083,16 +1101,39 @@ private bool SetLayoutFromElement(object o, PropertyInfo propInfo, ILoggingConfi
 
         private Layout TryCreateLayoutInstance(ILoggingConfigurationElement element, Type type)
         {
-            // Check if it is a Layout
-            if (!typeof(Layout).IsAssignableFrom(type))
+            return TryCreateInstance(element, type, _configurationItemFactory.Layouts);
+        } 
+
+        private Filter TryCreateFilterInstance(ILoggingConfigurationElement element, Type type)
+        {
+            return TryCreateInstance(element, type, _configurationItemFactory.Filters);
+        }
+
+        private T TryCreateInstance<T>(ILoggingConfigurationElement element, Type type, INamedItemFactory<T, Type> factory)
+            where T : class
+        {
+            // Check if correct type
+            if (!IsAssignableFrom<T>(type))
                 return null;
 
             // Check if the 'type' attribute has been specified
             string layoutTypeName = GetConfigItemTypeAttribute(element);
             if (layoutTypeName == null)
                 return null;
 
-            return _configurationItemFactory.Layouts.CreateInstance(ExpandSimpleVariables(layoutTypeName));
+            return factory.CreateInstance(ExpandSimpleVariables(layoutTypeName));
+        }
+
+        private static bool IsAssignableFrom<T>(Type type)
+        {
+            return typeof(T).IsAssignableFrom(type);
+        }
+
+        private void SetItemOnProperty(object o, PropertyInfo propInfo, ILoggingConfigurationElement element, object properyValue)
+        {
+            ConfigureObjectFromAttributes(properyValue, element, true);
+            ConfigureObjectFromElement(properyValue, element);
+            propInfo.SetValue(o, properyValue, null);
         }
 
         private void SetItemFromElement(object o, PropertyInfo propInfo, ILoggingConfigurationElement element)
@@ -1223,7 +1264,7 @@ private static string StripOptionalNamespacePrefix(string attributeValue)
 
             return attributeValue.Substring(p + 1);
         }
-       
+
         private static string GetName(Target target)
         {
             return string.IsNullOrEmpty(target.Name) ? target.GetType().Name : target.Name;

src/NLog/Filters/ConditionBasedFilter.cs

@@ -55,6 +55,8 @@ public class ConditionBasedFilter : Filter
         [RequiredParameter]
         public ConditionExpression Condition { get; set; }
 
+        internal FilterResult DefaultFilterResult { get; set; } = FilterResult.Neutral;
+
         /// <summary>
         /// Checks whether log event should be logged or not.
         /// </summary>
@@ -72,7 +74,7 @@ protected override FilterResult Check(LogEventInfo logEvent)
                 return Action;
             }
 
-            return FilterResult.Neutral;
+            return DefaultFilterResult;
         }
     }
 }

src/NLog/Internal/CollectionExtensions.cs

@@ -0,0 +1,77 @@
+// 
+// Copyright (c) 2004-2019 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.
+// 
+
+using System;
+using System.Collections.Generic;
+using JetBrains.Annotations;
+
+namespace NLog.Internal
+{
+    internal static class CollectionExtensions
+    {
+        /// <summary>
+        /// Memory optimized filtering
+        /// </summary>
+        /// <remarks>Passing state too avoid delegate capture and memory-allocations.</remarks>
+        [NotNull]
+        public static IList<TItem> Filter<TItem, TState>([NotNull] this IList<TItem> items, TState state, Func<TItem, TState, bool> filter)
+        {
+            var hasIgnoredLogEvents = false;
+            IList<TItem> filterLogEvents = null;
+            for (var i = 0; i < items.Count; ++i)
+            {
+                var item = items[i];
+                if (filter(item, state))
+                {
+                    if (hasIgnoredLogEvents && filterLogEvents == null)
+                    {
+                        filterLogEvents = new List<TItem>();
+                    }
+
+                    filterLogEvents?.Add(item);
+                }
+                else
+                {
+                    if (!hasIgnoredLogEvents && i > 0)
+                    {
+                        filterLogEvents = new List<TItem>();
+                        for (var j = 0; j < i; ++j)
+                            filterLogEvents.Add(items[j]);
+                    }
+                    hasIgnoredLogEvents = true;
+                }
+            }
+            return filterLogEvents ?? (hasIgnoredLogEvents ? ArrayHelper.Empty<TItem>() : items);
+        }
+    }
+}

src/NLog/Targets/Wrappers/FilteringTargetWrapper.cs

@@ -34,10 +34,12 @@
 namespace NLog.Targets.Wrappers
 {
     using System;
-    using Common;
-    using Conditions;
-    using Config;
-    using Internal;
+    using System.Collections.Generic;
+    using NLog.Common;
+    using NLog.Conditions;
+    using NLog.Config;
+    using NLog.Filters;
+    using NLog.Internal;
 
     /// <summary>
     /// Filters log entries based on a condition.
@@ -59,8 +61,6 @@ namespace NLog.Targets.Wrappers
     [Target("FilteringWrapper", IsWrapper = true)]
     public class FilteringTargetWrapper : WrapperTargetBase
     {
-        private static readonly object boxedBooleanTrue = true;
-
         /// <summary>
         /// Initializes a new instance of the <see cref="FilteringTargetWrapper" /> class.
         /// </summary>
@@ -90,16 +90,32 @@ public FilteringTargetWrapper(Target wrappedTarget, ConditionExpression conditio
         {
             WrappedTarget = wrappedTarget;
             Condition = condition;
-            OptimizeBufferReuse = GetType() == typeof(FilteringTargetWrapper);  // Class not sealed, reduce breaking changes
         }
 
         /// <summary>
         /// Gets or sets the condition expression. Log events who meet this condition will be forwarded 
         /// to the wrapped target.
         /// </summary>
         /// <docgen category='Filtering Options' order='10' />
+        public ConditionExpression Condition { get => (Filter as ConditionBasedFilter)?.Condition; set => Filter = CreateFilter(value); }
+
+        /// <summary>
+        /// Gets or sets the filter. Log events who evaluates to <see cref="FilterResult.Ignore"/> will be discarded
+        /// </summary>
+        /// <docgen category='Filtering Options' order='10' />
         [RequiredParameter]
-        public ConditionExpression Condition { get; set; }
+        public Filter Filter { get; set; }
+
+        /// <inheritdoc/>
+        protected override void InitializeTarget()
+        {
+            base.InitializeTarget();
+
+            if (!OptimizeBufferReuse && WrappedTarget != null && WrappedTarget.OptimizeBufferReuse)
+            {
+                OptimizeBufferReuse = GetType() == typeof(FilteringTargetWrapper); // Class not sealed, reduce breaking changes
+            }
+        }
 
         /// <summary>
         /// Checks the condition against the passed log event.
@@ -109,8 +125,7 @@ public FilteringTargetWrapper(Target wrappedTarget, ConditionExpression conditio
         /// <param name="logEvent">Log event.</param>
         protected override void Write(AsyncLogEventInfo logEvent)
         {
-            object v = Condition.Evaluate(logEvent.LogEvent);
-            if (boxedBooleanTrue.Equals(v))
+            if (ShouldLogEvent(logEvent, Filter))
             {
                 WrappedTarget.WriteAsyncLogEvent(logEvent);
             }
@@ -119,5 +134,35 @@ protected override void Write(AsyncLogEventInfo logEvent)
                 logEvent.Continuation(null);
             }
         }
+
+        /// <inheritdoc/>
+        protected override void Write(IList<AsyncLogEventInfo> logEvents)
+        {
+            var filterLogEvents = logEvents.Filter(Filter, ShouldLogEvent);
+            WrappedTarget.WriteAsyncLogEvents(filterLogEvents);
+        }
+
+        private static bool ShouldLogEvent(AsyncLogEventInfo logEvent, Filter filter)
+        {
+            var filterResult = filter.GetFilterResult(logEvent.LogEvent);
+            if (filterResult != FilterResult.Ignore && filterResult != FilterResult.IgnoreFinal)
+            {
+                return true;
+            }
+            else
+            {
+                logEvent.Continuation(null);
+                return false;
+            }
+        }
+
+        private static ConditionBasedFilter CreateFilter(ConditionExpression value)
+        {
+            if (value == null)
+            {
+                return null;
+            }
+            return new ConditionBasedFilter { Condition = value, DefaultFilterResult = FilterResult.Ignore };
+        }
     }
 }