[gh-88] Added limit on reporting of multiple iterations.

source/Runtime/Internal/Flow.cs

@@ -9,32 +9,52 @@ namespace SharpLab.Runtime.Internal {
     public static class Flow {
         private const int MaxReportLength = 20;
         private const int MaxReportItemCount = 3;
+        private const int MaxReportStepNotesPerLineCount = 3;
 
-        private static readonly List<Line> _lines = new List<Line>();
-        public static IReadOnlyList<Line> Lines => _lines;
+        private static readonly IDictionary<int, int> _stepNotesCountPerLine = new Dictionary<int, int>();
+        private static readonly List<Step> _steps = new List<Step>();
+        public static IReadOnlyList<Step> Steps => _steps;
 
         public static void ReportLineStart(int lineNumber) {
-            _lines.Add(new Line(lineNumber));
+            _steps.Add(new Step(lineNumber));
         }
 
         public static void ReportVariable<T>(string name, T value) {
-            var line = _lines[_lines.Count - 1];
-            var notes = line.Notes;
+            var step = _steps[_steps.Count - 1];
+            if (!_stepNotesCountPerLine.TryGetValue(step.LineNumber, out int countPerLine))
+                countPerLine = 0;
+            countPerLine += 1;
+            _stepNotesCountPerLine[step.LineNumber] = countPerLine;
+
+            if (countPerLine == MaxReportStepNotesPerLineCount + 1) {
+                if (step.Notes != null) // already has "…"
+                    return;
+                step.Notes = new StringBuilder("…");
+                _steps[_steps.Count - 1] = step;
+                return;
+            }
+
+            if (countPerLine > MaxReportStepNotesPerLineCount + 1)
+                return;
+
+            var notes = step.Notes;
+            if (notes == null) {
+                notes = new StringBuilder();
+                step.Notes = notes;
+            }
+
             if (notes.Length > 0)
                 notes.Append(", ");
             notes.Append(name).Append(": ");
             AppendValue(notes, value);
-            _lines[_lines.Count - 1] = line;
+            // Have to reassign in case we set Notes
+            _steps[_steps.Count - 1] = step;
         }
 
         public static void ReportException(object exception) {
-            var line = _lines[_lines.Count - 1];
-            line.Exception = exception;
-            _lines[_lines.Count - 1] = line;
-        }
-
-        private static bool HadException() {
-            return Marshal.GetExceptionPointers() != IntPtr.Zero || Marshal.GetExceptionCode() != 0;
+            var step = _steps[_steps.Count - 1];
+            step.Exception = exception;
+            _steps[_steps.Count - 1] = step;
         }
 
         private static StringBuilder AppendValue<T>(StringBuilder builder, T value) {
@@ -84,26 +104,16 @@ namespace SharpLab.Runtime.Internal {
         }
 
         [Serializable]
-        public struct Line {
-            private StringBuilder _notes;
-
-            public Line(int number) {
-                Number = number;
-                _notes = null;
+        public struct Step {
+            public Step(int lineNumber) {
+                LineNumber = lineNumber;
+                Notes = null;
                 Exception = null;
             }
 
-            public int Number { get; }
+            public int LineNumber { get; }
             public object Exception { get; internal set; }
-
-            public bool HasNotes => _notes != null;
-            public StringBuilder Notes {
-                get {
-                    if (_notes == null)
-                        _notes = new StringBuilder();
-                    return _notes;
-                }
-            }
+            public StringBuilder Notes { get; internal set; }
         }
     }
 }

source/Server/Execution/ExecutionResult.cs

@@ -5,18 +5,18 @@ using SharpLab.Runtime.Internal;
 namespace SharpLab.Server.Execution {
     [Serializable]
     public class ExecutionResult {
-        public ExecutionResult(string returnValue, IReadOnlyList<Flow.Line> flow) {
+        public ExecutionResult(string returnValue, IReadOnlyList<Flow.Step> flow) {
             ReturnValue = returnValue;
             Flow = flow;
         }
 
-        public ExecutionResult(Exception exception, IReadOnlyList<Flow.Line> flow) {
+        public ExecutionResult(Exception exception, IReadOnlyList<Flow.Step> flow) {
             Exception = exception;
             Flow = flow;
         }
 
         public string ReturnValue { get; }
         public Exception Exception { get; }
-        public IReadOnlyList<Flow.Line> Flow { get; }
+        public IReadOnlyList<Flow.Step> Flow { get; }
     }
 }

source/Server/Execution/Executor.cs

@@ -62,25 +62,25 @@ namespace SharpLab.Server.Execution {
                 writer.WriteProperty("exception", result.Exception.ToString());
             }
             writer.WritePropertyStartArray("flow");
-            foreach (var line in result.Flow) {
-                SerializeFlowLine(line, writer);
+            foreach (var step in result.Flow) {
+                SerializeFlowStep(step, writer);
             }
             writer.WriteEndArray();
             writer.WriteEndObject();
         }
 
-        private void SerializeFlowLine(Flow.Line line, IFastJsonWriter writer) {
-            if (!line.HasNotes && line.Exception == null) {
-                writer.WriteValue(line.Number);
+        private void SerializeFlowStep(Flow.Step step, IFastJsonWriter writer) {
+            if (step.Notes == null && step.Exception == null) {
+                writer.WriteValue(step.LineNumber);
                 return;
             }
 
             writer.WriteStartObject();
-            writer.WriteProperty("line", line.Number);
-            if (line.HasNotes)
-                writer.WriteProperty("notes", line.Notes);
-            if (line.Exception != null)
-                writer.WriteProperty("exception", line.Exception.GetType().Name);
+            writer.WriteProperty("line", step.LineNumber);
+            if (step.Notes != null)
+                writer.WriteProperty("notes", step.Notes);
+            if (step.Exception != null)
+                writer.WriteProperty("exception", step.Exception.GetType().Name);
             writer.WriteEndObject();
         }
 
@@ -93,7 +93,7 @@ namespace SharpLab.Server.Execution {
 
                     using (guardToken.Scope()) {
                         var result = m.Invoke(Activator.CreateInstance(c), null);
-                        return new ExecutionResult(result?.ToString(), Flow.Lines);
+                        return new ExecutionResult(result?.ToString(), Flow.Steps);
                     }
                 }
                 catch (Exception ex) {
@@ -101,7 +101,7 @@ namespace SharpLab.Server.Execution {
                         ex = invocationEx.InnerException;
 
                     Flow.ReportException(ex);
-                    return new ExecutionResult(ex, Flow.Lines);
+                    return new ExecutionResult(ex, Flow.Steps);
                 }
             }
 

source/Tests/ExecutionTests.cs

@@ -1,5 +1,6 @@
 using System.Collections.Generic;
 using System.Linq;
+using System.Runtime.Serialization;
 using System.Threading.Tasks;
 using Xunit;
 using AshMind.Extensions;
@@ -8,7 +9,9 @@ using MirrorSharp;
 using MirrorSharp.Testing;
 using SharpLab.Server;
 using SharpLab.Server.MirrorSharp.Internal;
+using Newtonsoft.Json;
 using Newtonsoft.Json.Linq;
+using System;
 
 namespace SharpLab.Tests {
     public class ExecutionTests {
@@ -25,12 +28,34 @@ namespace SharpLab.Tests {
 
             var result = await driver.SendSlowUpdateAsync<ExecutionResultData>();
             var errors = result.JoinErrors();
-            var lines = result.ExtensionResult.Flow
-                .Select(f => new { Line = (f as JObject)?.Value<int>("line") ?? f.Value<int>(), Exception = (f as JObject)?.Value<string>("exception") })
+            var steps = result.ExtensionResult.Flow
+                .Select(s => new { s.Line, s.Exception })
                 .ToArray();
 
             Assert.True(errors.IsNullOrEmpty(), errors);
-            Assert.Contains(new { Line = expectedLineNumber, Exception = expectedExceptionTypeName }, lines);
+            Assert.Contains(new { Line = expectedLineNumber, Exception = expectedExceptionTypeName }, steps);
+        }
+
+        [Fact]
+        public async Task SlowUpdate_ReportsLimitedNumberOfNotesPerLine() {
+            var driver = await NewTestDriverAsync(LoadCodeFromResource("Loops.For.10Iterations.cs"));
+
+            var result = await driver.SendSlowUpdateAsync<ExecutionResultData>();
+            var errors = result.JoinErrors();
+
+            var notes = string.Join(
+                ", ",
+                result.ExtensionResult.Flow
+                    .Where(s => s.Line == 3 && s.Notes != null)
+                    .Select(s => s.Notes)
+            );
+
+            Assert.True(errors.IsNullOrEmpty(), errors);
+            Assert.Equal("i: 0, i: 1, i: 2, …", notes);
+        }
+
+        private static int LineNumberFromFlowStep(JToken step) {
+            return (step as JObject)?.Value<int>("line") ?? step.Value<int>();
         }
 
         private static string LoadCodeFromResource(string resourceName) {
@@ -48,7 +73,34 @@ namespace SharpLab.Tests {
 
         private class ExecutionResultData {
             public string Exception { get; set; }
-            public IList<JToken> Flow { get; } = new List<JToken>();
-        }        
+            [JsonIgnore]
+            public IList<FlowStepData> Flow { get; } = new List<FlowStepData>();
+            [JsonProperty("flow")]
+            private IList<JToken> FlowRaw { get; } = new List<JToken>();
+
+            [OnDeserialized]
+            private void OnDeserialized(StreamingContext context) {
+                foreach (var token in FlowRaw) {
+                    Flow.Add(ParseStepData(token));
+                }
+            }
+
+            private FlowStepData ParseStepData(JToken token) {
+                if (token is JValue value)
+                    return new FlowStepData { Line = value.Value<int>() };
+
+                return new FlowStepData {
+                    Line = token.Value<int>("line"),
+                    Exception = token.Value<string>("exception"),
+                    Notes = token.Value<string>("notes")
+                };
+            }
+        }
+
+        private class FlowStepData {
+            public int Line { get; set; }
+            public string Exception { get; set; }
+            public string Notes { get; set; }
+        }
     }
 }

source/Tests/TestCode/Execution/Loops.For.10Iterations.cs

@@ -0,0 +1,6 @@
+public class C {
+    public void M() {
+        for (var i = 0; i < 10; i++) {
+        }
+    }
+}