trace2: add performance format target

Add the performance format target for TRACE2 tracing. This change
includes a few notable components:

1. A new GetMessage method to ensure message strings written to normal and
performance targets are not duplicated.
2. A new PerformanceFormatComponent class to track sizing of optional
properties of performance format messages.
3. A BuildSpan method that Trace2Message children use to create
correctly-sized "spans" for optional properties of performance format
messages. A span is a piece of the message beginning with a pipe (|) and
ending just before the next pipe or the end of the message.
4. A BuildTimeSpan method that adjusts spans for long/short times. In
future, when we have events that include performance format string span
components, we will need to add an additional method to handle them.

src/shared/Core.Tests/Trace2Tests.cs

@@ -1,6 +1,3 @@
-using System;
-using System.Text.RegularExpressions;
-using GitCredentialManager.Tests.Objects;
 using Xunit;
 
 namespace GitCredentialManager.Tests;
@@ -30,4 +27,14 @@ public void TryGetPipeName_Windows_Returns_Expected_Value(string input, string e
         Assert.True(isSuccessful);
         Assert.Matches(actual, expected);
     }
+
+    [Theory]
+    [InlineData(0.013772,    "  0.013772 ")]
+    [InlineData(26.316083,   " 26.316083 ")]
+    [InlineData(100.316083,  "100.316083 ")]
+    public void BuildTimeSpan_Match_Returns_Expected_String(double input, string expected)
+    {
+        var actual = Trace2Message.BuildTimeSpan(input);
+        Assert.Equal(expected, actual);
+    }
 }

src/shared/Core/Constants.cs

@@ -56,6 +56,7 @@ public static class EnvironmentVariables
             public const string GcmAllowWia           = "GCM_ALLOW_WINDOWSAUTH";
             public const string GitTrace2Event        = "GIT_TRACE2_EVENT";
             public const string GitTrace2Normal       = "GIT_TRACE2";
+            public const string GitTrace2Performance  = "GIT_TRACE2_PERF";
 
             /*
              * Unlike other environment variables, these proxy variables are normally lowercase only.
@@ -169,9 +170,10 @@ public static class Remote
 
             public static class Trace2
             {
-                public const string SectionName = "trace2";
-                public const string EventTarget = "eventtarget";
-                public const string NormalTarget = "normaltarget";
+                public const string SectionName       = "trace2";
+                public const string EventTarget       = "eventtarget";
+                public const string NormalTarget      = "normaltarget";
+                public const string PerformanceTarget = "perftarget";
             }
         }
 

src/shared/Core/ITrace2Writer.cs

@@ -10,7 +10,8 @@ namespace GitCredentialManager;
 public enum Trace2FormatTarget
 {
     Event,
-    Normal
+    Normal,
+    Performance
 }
 
 public interface ITrace2Writer : IDisposable
@@ -44,6 +45,9 @@ protected string Format(Trace2Message message)
             case Trace2FormatTarget.Normal:
                 sb.Append(message.ToNormalString());
                 break;
+            case Trace2FormatTarget.Performance:
+                sb.Append(message.ToPerformanceString());
+                break;
             default:
                 Console.WriteLine($"warning: unrecognized format target '{_formatTarget}', disabling TRACE2 tracing.");
                 Failed = true;

src/shared/Core/Settings.cs

@@ -533,6 +533,12 @@ public Trace2Settings GetTrace2Settings()
                 settings.FormatTargetsAndValues.Add(Trace2FormatTarget.Normal, value);
             }
 
+            if (TryGetSetting(Constants.EnvironmentVariables.GitTrace2Performance, KnownGitCfg.Trace2.SectionName,
+                    Constants.GitConfiguration.Trace2.PerformanceTarget, out value))
+            {
+                settings.FormatTargetsAndValues.Add(Trace2FormatTarget.Performance, value);
+            }
+
             return settings;
         }