Cache padding strings up to 120 spaces (#3036)

src/Microsoft.PowerShell.ConsoleHost/host/msh/ConsoleHostUserInterface.cs

@@ -1752,7 +1752,7 @@ namespace Microsoft.PowerShell
                         // is overridden by the tab
                         char charUnderCursor = GetCharacterUnderCursor(c);
 
-                        Write(new string(' ', leftover));
+                        Write(StringUtil.Padding(leftover));
                         RawUI.CursorPosition = c;
 
                         restOfLine = s[i] + (charUnderCursor + s.Substring(i + 1));

src/Microsoft.PowerShell.ConsoleHost/host/msh/PendingProgress.cs

@@ -689,7 +689,7 @@ namespace Microsoft.PowerShell
             }
 
             ArrayList result = new ArrayList();
-            string border = new string(' ', maxWidth);
+            string border = StringUtil.Padding(maxWidth);
 
             result.Add(border);
             RenderHelper(result, _topLevelNodes, 0, maxWidth, rawUI);

src/Microsoft.PowerShell.ConsoleHost/host/msh/ProgressNode.cs

@@ -171,7 +171,7 @@ namespace Microsoft.PowerShell
         void
         RenderFull(ArrayList strCollection, int indentation, int maxWidth, PSHostRawUserInterface rawUI, bool isFullPlus)
         {
-            string indent = new string(' ', indentation);
+            string indent = StringUtil.Padding(indentation);
 
             // First line: the activity
 
@@ -180,7 +180,7 @@ namespace Microsoft.PowerShell
                     rawUI, StringUtil.Format(" {0}{1} ", indent, this.Activity), maxWidth));
 
             indentation += 3;
-            indent = new string(' ', indentation);
+            indent = StringUtil.Padding(indentation);
 
             // Second line: the status description
 
@@ -209,7 +209,7 @@ namespace Microsoft.PowerShell
                             " {0}[{1}{2}] ",
                             indent,
                             new string('o', mercuryWidth),
-                            new string(' ', thermoWidth - mercuryWidth)),
+                            StringUtil.Padding(thermoWidth - mercuryWidth)),
                         maxWidth));
             }
 
@@ -291,7 +291,7 @@ namespace Microsoft.PowerShell
         void
         RenderCompact(ArrayList strCollection, int indentation, int maxWidth, PSHostRawUserInterface rawUI)
         {
-            string indent = new string(' ', indentation);
+            string indent = StringUtil.Padding(indentation);
 
             // First line: the activity
 
@@ -301,7 +301,7 @@ namespace Microsoft.PowerShell
                     StringUtil.Format(" {0}{1} ", indent, this.Activity), maxWidth));
 
             indentation += 3;
-            indent = new string(' ', indentation);
+            indent = StringUtil.Padding(indentation);
 
             // Second line: the status description with percentage and time remaining, if applicable.
 
@@ -372,7 +372,7 @@ namespace Microsoft.PowerShell
         void
         RenderMinimal(ArrayList strCollection, int indentation, int maxWidth, PSHostRawUserInterface rawUI)
         {
-            string indent = new string(' ', indentation);
+            string indent = StringUtil.Padding(indentation);
 
             // First line: Everything mushed into one line
 
@@ -512,7 +512,7 @@ namespace Microsoft.PowerShell
             // Start with 1 for the Activity
             int lines = 1;
             // Use 5 spaces as the heuristic indent. 5 spaces stand for the indent for the CurrentOperation of the first-level child node
-            var indent = new string(' ', 5);
+            var indent = StringUtil.Padding(5);
             var temp = new ArrayList();
 
             if (isFullPlus)

src/System.Management.Automation/commands/utility/FormatAndOutput/common/ComplexWriter.cs

@@ -8,6 +8,7 @@ using System.Collections.ObjectModel;
 using System.Collections.Specialized;
 using System.Text;
 using System.Globalization;
+using System.Management.Automation.Internal;
 
 namespace Microsoft.PowerShell.Commands.Internal.Format
 {
@@ -715,7 +716,7 @@ namespace Microsoft.PowerShell.Commands.Internal.Format
 
         internal static string PadLeft(string val, int count)
         {
-            return new string(' ', count) + val;
+            return StringUtil.Padding(count) + val;
         }
 
         private static readonly char[] s_newLineChar = new char[] { '\n' };

src/System.Management.Automation/commands/utility/FormatAndOutput/common/ListWriter.cs

@@ -4,6 +4,7 @@ Copyright (c) Microsoft Corporation.  All rights reserved.
 
 using System.Collections.Specialized;
 using System.Diagnostics;
+using System.Management.Automation.Internal;
 
 namespace Microsoft.PowerShell.Commands.Internal.Format
 {
@@ -86,7 +87,7 @@ namespace Microsoft.PowerShell.Commands.Internal.Format
                 if (propertyNameCellCounts[k] < _propertyLabelsDisplayLength)
                 {
                     // shorter than the max, add padding
-                    _propertyLabels[k] = propertyNames[k] + new string(' ', _propertyLabelsDisplayLength - propertyNameCellCounts[k]);
+                    _propertyLabels[k] = propertyNames[k] + StringUtil.Padding(_propertyLabelsDisplayLength - propertyNameCellCounts[k]);
                 }
                 else if (propertyNameCellCounts[k] > _propertyLabelsDisplayLength)
                 {
@@ -181,7 +182,7 @@ namespace Microsoft.PowerShell.Commands.Internal.Format
                 else
                 {
                     if (padding == null)
-                        padding = prependString = new string(' ', _propertyLabelsDisplayLength);
+                        padding = StringUtil.Padding(_propertyLabelsDisplayLength);
 
                     prependString = padding;
                 }
@@ -209,7 +210,7 @@ namespace Microsoft.PowerShell.Commands.Internal.Format
             StringCollection sc = StringManipulationHelper.GenerateLines(lo.DisplayCells, line, fieldCellCount, fieldCellCount);
 
             // padding to use in the lines after the first
-            string padding = new string(' ', _propertyLabelsDisplayLength);
+            string padding = StringUtil.Padding(_propertyLabelsDisplayLength);
 
             // display the string collection
             for (int k = 0; k < sc.Count; k++)

src/System.Management.Automation/commands/utility/FormatAndOutput/common/TableWriter.cs

@@ -3,6 +3,7 @@ Copyright (c) Microsoft Corporation.  All rights reserved.
 --********************************************************************/
 
 using System.Collections.Specialized;
+using System.Management.Automation.Internal;
 using System.Text;
 
 namespace Microsoft.PowerShell.Commands.Internal.Format
@@ -248,7 +249,7 @@ namespace Microsoft.PowerShell.Commands.Internal.Format
                     // skipping the first ones, add a separator for catenation
                     for (int j = 0; j < scArray[k].Count; j++)
                     {
-                        scArray[k][j] = new string(' ', ScreenInfo.separatorCharacterCount) + scArray[k][j];
+                        scArray[k][j] = StringUtil.Padding(ScreenInfo.separatorCharacterCount) + scArray[k][j];
                     }
                 }
                 else
@@ -258,7 +259,7 @@ namespace Microsoft.PowerShell.Commands.Internal.Format
                     {
                         for (int j = 0; j < scArray[k].Count; j++)
                         {
-                            scArray[k][j] = new string(' ', _startColumn) + scArray[k][j];
+                            scArray[k][j] = StringUtil.Padding(_startColumn) + scArray[k][j];
                         }
                     }
                 }
@@ -288,7 +289,7 @@ namespace Microsoft.PowerShell.Commands.Internal.Format
                 {
                     for (int j = 0; j < paddingEntries; j++)
                     {
-                        scArray[col].Add(new string(' ', paddingBlanks));
+                        scArray[col].Add(StringUtil.Padding(paddingBlanks));
                     }
                 }
             }
@@ -339,14 +340,14 @@ namespace Microsoft.PowerShell.Commands.Internal.Format
                 // pad with a blank (or any character that ALWAYS maps to a single screen cell
                 if (k > 0)
                 {
-                    sb.Append(new string(' ', ScreenInfo.separatorCharacterCount));
+                    sb.Append(StringUtil.Padding(ScreenInfo.separatorCharacterCount));
                 }
                 else
                 {
                     // add indentation padding if needed
                     if (_startColumn > 0)
                     {
-                        sb.Append(new string(' ', _startColumn));
+                        sb.Append(StringUtil.Padding(_startColumn));
                     }
                 }
                 sb.Append(GenerateRowField(values[k], _si.columnInfo[k].width, alignment[k], dc));
@@ -372,7 +373,7 @@ namespace Microsoft.PowerShell.Commands.Internal.Format
                 {
                     case TextAlignment.Right:
                         {
-                            s = new string(' ', padCount) + s;
+                            s = StringUtil.Padding(padCount) + s;
                         }
                         break;
 
@@ -382,14 +383,14 @@ namespace Microsoft.PowerShell.Commands.Internal.Format
                             int padLeft = padCount / 2;
                             int padRight = padCount - padLeft;
 
-                            s = new string(' ', padLeft) + s + new string(' ', padRight);
+                            s = StringUtil.Padding(padLeft) + s + StringUtil.Padding(padRight);
                         }
                         break;
 
                     default:
                         {
                             // left align is the default
-                            s += new string(' ', padCount);
+                            s += StringUtil.Padding(padCount);
                         }
                         break;
                 }

src/System.Management.Automation/engine/parser/token.cs

@@ -7,6 +7,7 @@ using System.Collections.Generic;
 using System.Collections.ObjectModel;
 using System.Diagnostics.CodeAnalysis;
 using System.Globalization;
+using System.Management.Automation.Internal;
 using System.Text;
 
 namespace System.Management.Automation.Language
@@ -1236,7 +1237,7 @@ namespace System.Management.Automation.Language
 
         internal virtual string ToDebugString(int indent)
         {
-            return string.Format(CultureInfo.InvariantCulture, "{0}{1}: <{2}>", new string(' ', indent), _kind, Text);
+            return string.Format(CultureInfo.InvariantCulture, "{0}{1}: <{2}>", StringUtil.Padding(indent), _kind, Text);
         }
     }
 
@@ -1256,7 +1257,7 @@ namespace System.Management.Automation.Language
         internal override string ToDebugString(int indent)
         {
             return string.Format(CultureInfo.InvariantCulture,
-                "{0}{1}: <{2}> Value:<{3}> Type:<{4}>", new string(' ', indent), Kind, Text, _value, _value.GetType().Name);
+                "{0}{1}: <{2}> Value:<{3}> Type:<{4}>", StringUtil.Padding(indent), Kind, Text, _value, _value.GetType().Name);
         }
 
         /// <summary>
@@ -1298,7 +1299,7 @@ namespace System.Management.Automation.Language
         internal override string ToDebugString(int indent)
         {
             return string.Format(CultureInfo.InvariantCulture,
-                "{0}{1}: <-{2}{3}>", new string(' ', indent), Kind, _parameterName, _usedColon ? ":" : "");
+                "{0}{1}: <-{2}{3}>", StringUtil.Padding(indent), Kind, _parameterName, _usedColon ? ":" : "");
         }
     }
 
@@ -1326,7 +1327,7 @@ namespace System.Management.Automation.Language
         internal override string ToDebugString(int indent)
         {
             return string.Format(CultureInfo.InvariantCulture,
-                "{0}{1}: <{2}> Name:<{3}>", new string(' ', indent), Kind, Text, Name);
+                "{0}{1}: <{2}> Name:<{3}>", StringUtil.Padding(indent), Kind, Text, Name);
         }
     }
 
@@ -1349,7 +1350,7 @@ namespace System.Management.Automation.Language
         internal override string ToDebugString(int indent)
         {
             return string.Format(CultureInfo.InvariantCulture,
-                "{0}{1}: <{2}> Value:<{3}>", new string(' ', indent), Kind, Text, Value);
+                "{0}{1}: <{2}> Value:<{3}>", StringUtil.Padding(indent), Kind, Text, Value);
         }
     }
 

src/System.Management.Automation/utils/StringUtil.cs

@@ -3,6 +3,7 @@ Copyright (c) Microsoft Corporation.  All rights reserved.
 --********************************************************************/
 
 using System.Management.Automation.Host;
+using System.Threading;
 using Dbg = System.Management.Automation.Diagnostics;
 
 namespace System.Management.Automation.Internal
@@ -68,6 +69,25 @@ namespace System.Management.Automation.Internal
 
             return result;
         }
+
+        // Typical padding is at most a screen's width, any more than that and we won't bother caching.
+        private const int IndentCacheMax = 120;
+        private static readonly string[] IndentCache = new string[IndentCacheMax];
+        internal static string Padding(int countOfSpaces)
+        {
+            if (countOfSpaces >= IndentCacheMax)
+                return new string(' ', countOfSpaces);
+
+            var result = IndentCache[countOfSpaces];
+
+            if (result == null)
+            {
+                Interlocked.CompareExchange(ref IndentCache[countOfSpaces], new string(' ', countOfSpaces), null);
+                result = IndentCache[countOfSpaces];
+            }
+
+            return result;
+        }
     }
 }   // namespace