--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Implab/Diagnostics/SimpleTraceListener.cs	Mon Feb 12 17:03:37 2018 +0300
@@ -0,0 +1,114 @@
+using System;
+using System.Diagnostics;
+using System.IO;
+
+namespace Implab.Diagnostics {
+    public class SimpleTraceListener : TextWriterTraceListener {
+        public SimpleTraceListener() {
+        }
+
+        public SimpleTraceListener(Stream stream) : base(stream) {
+        }
+
+        public SimpleTraceListener(TextWriter writer) : base(writer) {
+        }
+
+        public SimpleTraceListener(string fileName) : base(fileName) {
+        }
+
+        public SimpleTraceListener(Stream stream, string name) : base(stream, name) {
+        }
+
+        public SimpleTraceListener(TextWriter writer, string name) : base(writer, name) {
+        }
+
+        public SimpleTraceListener(string fileName, string name) : base(fileName, name) {
+        }
+
+        public override void TraceData(TraceEventCache eventCache, string source, TraceEventType eventType, int id, object data) {
+            switch (id) {
+                case TraceEventCodes.StartLogicalOperation:
+                    TraceEvent(eventCache, source, eventType, id, "+{0}", data);
+                    break;
+                case TraceEventCodes.StopLogicalOperation:
+                    TraceEvent(eventCache, source, eventType, id, FormatStopLogicalOperation(data));
+                    break;
+                default:
+                    TraceEvent(eventCache, source, eventType, id, data?.ToString());
+                    break;
+            }
+        }
+
+        string FormatStopLogicalOperation(object data) {
+            if (data is LogicalOperation op) {
+                return string.Format("-{0} ({1})", op, FormatTimespan(op.OperationStopwatch.Elapsed));
+            } else {
+                return data?.ToString();
+            }
+        }
+
+        string FormatTimespan(TimeSpan value) {
+            if (value.TotalSeconds < 10) {
+                return value.Milliseconds.ToString() + "ms";
+            } else if (value.TotalSeconds < 30) {
+                return string.Format("{0:0.###}s", value.TotalSeconds);
+            } else {
+                return value.ToString();
+            }
+        }
+
+        public override void TraceData(TraceEventCache eventCache, string source, TraceEventType eventType, int id, params object[] data) {
+            var prev = IndentLevel;
+            IndentLevel += eventCache.LogicalOperationStack.Count;
+            try {
+                base.TraceData(eventCache, source, eventType, id, data);
+            } finally {
+                IndentLevel = prev;
+            }
+        }
+
+        public override void TraceEvent(TraceEventCache eventCache, string source, TraceEventType eventType, int id) {
+            var prev = IndentLevel;
+            IndentLevel += eventCache.LogicalOperationStack.Count;
+            try {
+                base.TraceEvent(eventCache, source, eventType, id);
+            } finally {
+                IndentLevel = prev;
+            }
+        }
+
+        public override void TraceEvent(TraceEventCache eventCache, string source, TraceEventType eventType, int id, string format, params object[] args) {
+            TraceEvent(eventCache, source, eventType, id, String.Format(format, args));
+        }
+
+        public override void TraceEvent(TraceEventCache eventCache, string source, TraceEventType eventType, int id, string message) {
+            var prev = IndentLevel;
+            IndentLevel += eventCache.LogicalOperationStack.Count;
+            try {
+                LogicalOperation operation = null;
+                if (eventCache.LogicalOperationStack.Count > 0)
+                    operation = eventCache.LogicalOperationStack.Peek() as LogicalOperation;
+
+                if (operation != null) {
+                    base.TraceData(eventCache, source, eventType, id, FormatTimespan(operation.OperationStopwatch.Elapsed) + ": " + message);
+                } else {
+                    base.TraceData(eventCache, source, eventType, id, message);
+                }
+            } finally {
+                IndentLevel = prev;
+            }
+        }
+
+        public override void TraceTransfer(TraceEventCache eventCache, string source, int id, string message, Guid relatedActivityId) {
+            var prev = IndentLevel;
+            IndentLevel += eventCache.LogicalOperationStack.Count;
+            try {
+                base.TraceTransfer(eventCache, source, id, message, relatedActivityId);
+            } finally {
+                IndentLevel = prev;
+            }
+        }
+
+
+    }
+}
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