From 26fa4534a212b6948bc5074be77dc61fb12d0d26 Mon Sep 17 00:00:00 2001
From: laurentiu021 <laurentiu021@users.noreply.github.com>
Date: Thu, 11 Jun 2026 13:43:16 +0300
Subject: [PATCH] refactor: use [GeneratedRegex] and SearchValues on log hot
 paths
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Two .NET 10 idiom modernizations on hot/testable paths, behavior unchanged:

- LogService is now a static partial class; the constant fallback user-path
  pattern is source-generated via [GeneratedRegex] (FallbackUserPathRegex)
  instead of new Regex(..., Compiled) — build-time compiled, no runtime IL
  emit, AOT-friendly. The dynamic interpolated branch (built from the real
  user-profile dir) stays a runtime Regex since it can't be source-generated.
- EventLogService.FirstLine hoists a static SearchValues<char> for the \r\n
  scan and uses span IndexOfAny, removing the per-call char[] allocation on a
  path that runs once per projected event record (thousands per query).

Both regex patterns and the FirstLine result are byte-identical to before.
---
 SysManager/SysManager/Services/EventLogService.cs |  7 ++++++-
 SysManager/SysManager/Services/LogService.cs      | 10 +++++++---
 2 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/SysManager/SysManager/Services/EventLogService.cs b/SysManager/SysManager/Services/EventLogService.cs
index 33f5a93..6e70581 100644
--- a/SysManager/SysManager/Services/EventLogService.cs
+++ b/SysManager/SysManager/Services/EventLogService.cs
@@ -2,6 +2,7 @@
 // Author: laurentiu021 · https://github.com/laurentiu021/SystemManager
 // License: MIT
 
+using System.Buffers;
 using System.Diagnostics.Eventing.Reader;
 using SysManager.Models;
 
@@ -113,10 +114,14 @@ private static string SafeFormatMessage(EventRecord rec)
         catch (InvalidOperationException) { return "(message not available)"; }
     }
 
+    // Hoisted so the newline scan in FirstLine — run once per projected event
+    // record, potentially thousands per query — doesn't allocate a char[] per call.
+    private static readonly SearchValues<char> Newlines = SearchValues.Create("\r\n");
+
     private static string FirstLine(string s)
     {
         if (string.IsNullOrEmpty(s)) return "";
-        var i = s.IndexOfAny(new[] { '\r', '\n' });
+        var i = s.AsSpan().IndexOfAny(Newlines);
         return (i < 0 ? s : s[..i]).Trim();
     }
 
diff --git a/SysManager/SysManager/Services/LogService.cs b/SysManager/SysManager/Services/LogService.cs
index e5a5a9b..cd6167e 100644
--- a/SysManager/SysManager/Services/LogService.cs
+++ b/SysManager/SysManager/Services/LogService.cs
@@ -9,7 +9,7 @@
 
 namespace SysManager.Services;
 
-public static class LogService
+public static partial class LogService
 {
     public static Logger? Logger { get; private set; }
 
@@ -33,10 +33,14 @@ private static Regex BuildUserPathRegex()
                 return new Regex($@"(?i)({escaped})[^\\]+", RegexOptions.Compiled);
             }
         }
-        // Fallback: match any drive letter followed by \Users\<username>
-        return new Regex(@"(?i)([A-Z]:\\Users\\)[^\\]+", RegexOptions.Compiled);
+        // Fallback: match any drive letter followed by \Users\<username>.
+        // This branch is a constant pattern, so it is source-generated.
+        return FallbackUserPathRegex();
     }
 
+    [GeneratedRegex(@"(?i)([A-Z]:\\Users\\)[^\\]+")]
+    private static partial Regex FallbackUserPathRegex();
+
     public static void Init()
     {
         Directory.CreateDirectory(LogDir);