Merge pull request #2826 from pharring/TokenStream

Allocation reductions in formatting.

src/Workspaces/Core/Portable/Formatting/Engine/AbstractFormatEngine.cs

@@ -443,18 +443,19 @@ private SyntaxToken FindCorrectBaseTokenOfRelativeIndentBlockOperation(IndentBlo
                 // always create task 1 more than current processor count
                 var partitions = partitioner.GetPartitions(this.TaskExecutor == TaskExecutor.Synchronous ? 1 : Environment.ProcessorCount + 1);
 
-                var tasks = new List<Task>(
-                        partitions.Select(
-                            partition =>
-                                this.TaskExecutor.StartNew(
-                                    () =>
+                var tasks = new Task[partitions.Count];
+                for (int i = 0; i < partitions.Count; i++)
                 {
-                    cancellationToken.ThrowIfCancellationRequested();
-                    partition.Do(operationPair => ApplySpaceAndWrappingOperationsBody(context, tokenStream, operationPair, applier, cancellationToken));
-                },
-                                    cancellationToken)));
+                    var partition = partitions[i];
+                    tasks[i] = this.TaskExecutor.StartNew(() =>
+                    {
+                        cancellationToken.ThrowIfCancellationRequested();
+                        partition.Do(operationPair => ApplySpaceAndWrappingOperationsBody(context, tokenStream, operationPair, applier, cancellationToken));
+                    },
+                    cancellationToken);
+                }
 
-                Task.WaitAll(tasks.ToArray(), cancellationToken);
+                Task.WaitAll(tasks, cancellationToken);
             }
         }
 

src/Workspaces/Core/Portable/Formatting/Engine/AbstractFormattingResult.cs

@@ -62,15 +62,21 @@ private IList<TextChange> CreateTextChanges(CancellationToken cancellationToken)
             using (Logger.LogBlock(FunctionId.Formatting_CreateTextChanges, cancellationToken))
             {
                 var data = this.TokenStream.GetTriviaDataWithTokenPair(cancellationToken);
-                var result = this.TaskExecutor
-                                 .Filter(data, d => d.Item2.ContainsChanges, d => d, cancellationToken)
-                                 .SelectMany(d => CreateTextChange(d.Item1.Item1, d.Item1.Item2, d.Item2));
 
-                return result.ToList();
+                var filtered = this.TaskExecutor
+                                 .Filter(data, d => d.Item2.ContainsChanges, d => d, cancellationToken);
+
+                var result = new List<TextChange>();
+                foreach (var f in filtered)
+                {
+                    AddTextChanges(result, f.Item1.Item1, f.Item1.Item2, f.Item2);
+                }
+
+                return result;
             }
         }
 
-        private IEnumerable<TextChange> CreateTextChange(SyntaxToken token1, SyntaxToken token2, TriviaData data)
+        private void AddTextChanges(List<TextChange> list, SyntaxToken token1, SyntaxToken token2, TriviaData data)
         {
             var span = TextSpan.FromBounds(token1.RawKind == 0 ? this.TreeInfo.StartPosition : token1.Span.End, token2.RawKind == 0 ? this.TreeInfo.EndPosition : token2.SpanStart);
             var originalString = this.TreeInfo.GetTextBetween(token1, token2);
@@ -78,7 +84,7 @@ private IEnumerable<TextChange> CreateTextChange(SyntaxToken token1, SyntaxToken
             foreach (var change in data.GetTextChanges(span))
             {
                 var oldText = (change.Span == span) ? originalString : originalString.Substring(change.Span.Start - span.Start, change.Span.Length);
-                yield return change.SimpleDiff(oldText);
+                list.Add(change.SimpleDiff(oldText));
             }
         }
 

src/Workspaces/Core/Portable/Formatting/Engine/AbstractTriviaDataFactory.FormattedWhitespace.cs

@@ -35,7 +35,7 @@ private string CreateString(string newLine)
                         builder.Append(newLine);
                     }
 
-                    builder.Append(this.Spaces.CreateIndentationString(this.OptionSet.GetOption(FormattingOptions.UseTabs, this.Language), this.OptionSet.GetOption(FormattingOptions.TabSize, this.Language)));
+                    builder.AppendIndentationString(this.Spaces, this.OptionSet.GetOption(FormattingOptions.UseTabs, this.Language), this.OptionSet.GetOption(FormattingOptions.TabSize, this.Language));
                     return StringBuilderPool.ReturnAndFree(builder);
                 }
 

src/Workspaces/Core/Portable/Formatting/Engine/TokenStream.Changes.cs

@@ -9,62 +9,35 @@ namespace Microsoft.CodeAnalysis.Formatting
     internal partial class TokenStream
     {
         /// <summary>
-        /// thread-safe collection that holds onto changes
+        /// Thread-safe collection that holds onto changes
         /// </summary>
-        private class Changes
+        private struct Changes
         {
             public const int BeginningOfTreeKey = -1;
             public const int EndOfTreeKey = -2;
 
-            private readonly ConcurrentDictionary<int, TriviaData> _map;
+            // Created lazily
+            private ConcurrentDictionary<int, TriviaData> _map;
 
-            public Changes()
-            {
-                _map = new ConcurrentDictionary<int, TriviaData>();
-            }
-
-            public bool Contains(int key)
-            {
-                return _map.ContainsKey(key);
-            }
-
-            public TriviaData this[int key]
-            {
-                get
-                {
-                    return _map[key];
-                }
-            }
-
-            public void Add(int key, TriviaData triviaInfo)
-            {
-                Contract.ThrowIfTrue(this.Contains(key));
-
-                _map.TryAdd(key, triviaInfo);
-            }
-
-            public void Replace(int key, TriviaData triviaInfo)
-            {
-                Contract.ThrowIfFalse(this.Contains(key));
-
-                _map[key] = triviaInfo;
-            }
-
-            public void Remove(int pairIndex)
+            public bool TryRemove(int pairIndex)
             {
                 TriviaData temp;
-                _map.TryRemove(pairIndex, out temp);
+                return _map?.TryRemove(pairIndex, out temp) ?? false;
             }
 
             public void AddOrReplace(int key, TriviaData triviaInfo)
             {
-                if (this.Contains(key))
-                {
-                    Replace(key, triviaInfo);
-                    return;
-                }
+                // PERF: Set the concurrency level to 1 because, while the dictionary has to be thread-safe,
+                // there is very little contention in formatting. A lower concurrency level reduces object
+                // allocations which are used internally by ConcurrentDictionary for locking.
+                var map = LazyInitialization.EnsureInitialized(ref _map, () => new ConcurrentDictionary<int, TriviaData>(concurrencyLevel: 1, capacity: 8));
+                map[key] = triviaInfo;
+            }
 
-                Add(key, triviaInfo);
+            public bool TryGet(int key, out TriviaData triviaInfo)
+            {
+                triviaInfo = null;
+                return _map?.TryGetValue(key, out triviaInfo) ?? false;
             }
         }
     }

src/Workspaces/Core/Portable/Formatting/Engine/TokenStream.cs

@@ -39,7 +39,7 @@ internal partial class TokenStream
         private readonly OptionSet _optionSet;
 
         // hold onto information that are made to original trivia info
-        private readonly Changes _changes;
+        private Changes _changes;
 
         // factory that will cache trivia info
         private readonly AbstractTriviaDataFactory _factory;
@@ -65,7 +65,6 @@ public TokenStream(TreeData treeData, OptionSet optionSet, TextSpan spanToFormat
                 Contract.Requires(this.TokenCount > 0);
 
                 // initialize trivia related info
-                _changes = new Changes();
                 _cachedOriginalTriviaInfo = new TriviaData[this.TokenCount - 1];
 
                 _tokenToIndexMap = new Dictionary<SyntaxToken, int>(this.TokenCount);
@@ -268,28 +267,14 @@ public void ApplyChange(int pairIndex, TriviaData data)
 
             // do reference equality check
             var sameAsOriginal = GetOriginalTriviaData(pairIndex) == data;
-
-            if (_changes.Contains(pairIndex))
+            if (sameAsOriginal)
             {
-                if (sameAsOriginal)
-                {
-                    _changes.Remove(pairIndex);
-                    return;
-                }
-
-                // okay it already exist.
-                // replace existing one
-                _changes.Replace(pairIndex, data);
-                return;
+                _changes.TryRemove(pairIndex);
             }
-
-            // triviaInfo is same as original, nothing to do here.
-            if (sameAsOriginal)
+            else
             {
-                return;
+                _changes.AddOrReplace(pairIndex, data);
             }
-
-            _changes.Add(pairIndex, data);
         }
 
         public int GetCurrentColumn(SyntaxToken token)
@@ -465,9 +450,10 @@ public TriviaData GetTriviaDataAtBeginningOfTree()
         {
             Contract.ThrowIfFalse(this.FormatBeginningOfTree);
 
-            if (_changes.Contains(Changes.BeginningOfTreeKey))
+            TriviaData data;
+            if (_changes.TryGet(Changes.BeginningOfTreeKey, out data))
             {
-                return _changes[Changes.BeginningOfTreeKey];
+                return data;
             }
 
             Contract.Requires(_treeData.IsFirstToken(this.FirstTokenInStream.Token));
@@ -478,9 +464,10 @@ public TriviaData GetTriviaDataAtEndOfTree()
         {
             Contract.ThrowIfFalse(this.FormatEndOfTree);
 
-            if (_changes.Contains(Changes.EndOfTreeKey))
+            TriviaData data;
+            if (_changes.TryGet(Changes.EndOfTreeKey, out data))
             {
-                return _changes[Changes.EndOfTreeKey];
+                return data;
             }
 
             Contract.Requires(_treeData.IsLastToken(this.LastTokenInStream.Token));
@@ -491,9 +478,10 @@ public TriviaData GetTriviaData(int pairIndex)
         {
             Contract.ThrowIfFalse(0 <= pairIndex && pairIndex < this.TokenCount - 1);
 
-            if (_changes.Contains(pairIndex))
+            TriviaData data;
+            if (_changes.TryGet(pairIndex, out data))
             {
-                return _changes[pairIndex];
+                return data;
             }
 
             // no change between two tokens, return trivia info from original code

src/Workspaces/Core/Portable/Formatting/FormattingExtensions.cs

@@ -8,6 +8,7 @@
 using Microsoft.CodeAnalysis.Shared.Extensions;
 using Microsoft.CodeAnalysis.Text;
 using Roslyn.Utilities;
+using System.Text;
 
 namespace Microsoft.CodeAnalysis.Formatting
 {
@@ -122,6 +123,20 @@ public static string CreateIndentationString(this int desiredIndentation, bool u
             return new string('\t', numberOfTabs) + new string(' ', numberOfSpaces);
         }
 
+        public static StringBuilder AppendIndentationString(this StringBuilder sb, int desiredIndentation, bool useTab, int tabSize)
+        {
+            int numberOfTabs = 0;
+            int numberOfSpaces = Math.Max(0, desiredIndentation);
+
+            if (useTab)
+            {
+                numberOfTabs = desiredIndentation / tabSize;
+                numberOfSpaces -= numberOfTabs * tabSize;
+            }
+
+            return sb.Append('\t', repeatCount: numberOfTabs).Append(' ', repeatCount: numberOfSpaces);
+        }
+
         public static void ProcessTextBetweenTokens(
             this string text,
             TreeData treeInfo,
@@ -168,9 +183,8 @@ public static string CreateIndentationString(this int desiredIndentation, bool u
             }
 
             var newIndentation = GetNewIndentationForComments(triviaText, nonWhitespaceCharIndex, forceIndentation, indentation, indentationDelta, tabSize);
-            var newIndentationString = newIndentation.CreateIndentationString(useTab, tabSize);
 
-            builder.Append(newIndentationString);
+            builder.AppendIndentationString(newIndentation, useTab, tabSize);
             if (!isEmptyString)
             {
                 builder.Append(triviaText, nonWhitespaceCharIndex, triviaText.Length - nonWhitespaceCharIndex);
@@ -209,9 +223,7 @@ public static string CreateIndentationString(this int desiredIndentation, bool u
                 if (nonWhitespaceCharIndex >= 0)
                 {
                     var newIndentation = GetNewIndentationForComments(line, nonWhitespaceCharIndex, forceIndentation, indentation, indentationDelta, tabSize);
-                    var newIndentationString = newIndentation.CreateIndentationString(useTab, tabSize);
-
-                    builder.Append(newIndentationString);
+                    builder.AppendIndentationString(newIndentation, useTab, tabSize);
                     builder.Append(line, nonWhitespaceCharIndex, line.Length - nonWhitespaceCharIndex);
                 }
 

src/Workspaces/Core/Portable/Formatting/TriviaEngine/AbstractTriviaFormatter.cs

@@ -811,12 +811,12 @@ private string GetWhitespaceString(LineColumn lineColumn, LineColumnDelta delta)
             // space indicates indentation
             if (delta.Lines > 0 || lineColumn.Column == 0)
             {
-                sb.Append(delta.Spaces.CreateIndentationString(useTabs, tabSize));
+                sb.AppendIndentationString(delta.Spaces, useTabs, tabSize);
                 return StringBuilderPool.ReturnAndFree(sb);
             }
 
             // space indicates space between two noisy trivia or tokens
-            sb.Append(GetSpaces(delta.Spaces));
+            sb.Append(' ', repeatCount: delta.Spaces);
             return StringBuilderPool.ReturnAndFree(sb);
         }
 

src/Workspaces/VisualBasic/Portable/Formatting/Engine/Trivia/TriviaDataFactory.LineContinuationTrivia.vb

@@ -35,7 +35,7 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Formatting
                 builder.Append(" "c)
                 builder.Append(SyntaxFacts.GetText(SyntaxKind.LineContinuationTrivia))
 
-                builder.Append(Me.Spaces.CreateIndentationString(Me.OptionSet.GetOption(FormattingOptions.UseTabs, LanguageNames.VisualBasic), Me.OptionSet.GetOption(FormattingOptions.TabSize, LanguageNames.VisualBasic)))
+                builder.AppendIndentationString(Me.Spaces, Me.OptionSet.GetOption(FormattingOptions.UseTabs, LanguageNames.VisualBasic), Me.OptionSet.GetOption(FormattingOptions.TabSize, LanguageNames.VisualBasic))
                 Return StringBuilderPool.ReturnAndFree(builder)
             End Function