fix: make JobLogger thread-safe

docs/code-review/02-joblogger-thread-safety.md

@@ -2,7 +2,7 @@
 
 **Priority:** 🔴 Critical
 **File:** `src/ArmRipper.Core/Infrastructure/JobLogger.cs`
-**Status:** ⬜ Todo
+**Status:** ✅ Done
 
 ---
 

docs/code-review/README.md

@@ -25,7 +25,7 @@ proposed fix.
 | # | Task | Priority | Status | Assignee |
 |---|------|----------|--------|----------|
 | 1 | [Fix sync-over-async in `StartImportJob`](01-fix-sync-over-async.md) | 🔴 Critical | ✅ Done | — |
-| 2 | [Fix `JobLogger` thread-safety](02-joblogger-thread-safety.md) | 🔴 Critical | ⬜ Todo | — |
+| 2 | [Fix `JobLogger` thread-safety](02-joblogger-thread-safety.md) | 🔴 Critical | ✅ Done | — |
 | 3 | [Fix `CheckMediaPresent` async gap & missing failure state](03-checkmedia-async.md) | 🔴 Critical | ⬜ Todo | — |
 
 ### 🟡 Medium (correctness / maintainability)
@@ -84,9 +84,9 @@ proposed fix.
 
 | Status | Count |
 |--------|-------|
-| ⬜ Todo | 26 |
+| ⬜ Todo | 25 |
 | 🔄 In Progress | 0 |
-| ✅ Done | 10 |
+| ✅ Done | 11 |
 
 ---
 

src/ArmRipper.Core/Infrastructure/JobLogger.cs

@@ -8,6 +8,8 @@ public sealed class JobLogger : ILogger
     private readonly string _logPath;
     private readonly StreamWriter _fileWriter;
     private readonly ILogger _inner;
+    private readonly object _writeLock = new();
+    private bool _disposed;
 
     public JobLogger(string jobId, string logDirectory, ILogger inner)
     {
@@ -21,7 +23,11 @@ public JobLogger(string jobId, string logDirectory, ILogger inner)
     public void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Exception? exception, Func<TState, Exception?, string> formatter)
     {
         var line = $"[{DateTime.Now:yyyy-MM-dd HH:mm:ss}] [{logLevel}] {formatter(state, exception)}";
-        _fileWriter.WriteLine(line);
+        lock (_writeLock)
+        {
+            if (_disposed) return;
+            _fileWriter.WriteLine(line);
+        }
         _inner.Log(logLevel, eventId, state, exception, formatter);
     }
 
@@ -31,13 +37,18 @@ public void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Except
 
     public void Dispose()
     {
-        _fileWriter.Flush();
-        _fileWriter.Dispose();
+        lock (_writeLock)
+        {
+            if (_disposed) return;
+            _disposed = true;
+            _fileWriter.Flush();
+            _fileWriter.Dispose();
+        }
     }
 
-    public async ValueTask DisposeAsync()
+    public ValueTask DisposeAsync()
     {
-        await _fileWriter.FlushAsync();
-        await _fileWriter.DisposeAsync();
+        Dispose();
+        return ValueTask.CompletedTask;
     }
 }

tests/ArmRipper.Core.Tests/JobLoggerTests.cs

@@ -0,0 +1,50 @@
+using ArmRipper.Core.Infrastructure;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Logging.Abstractions;
+
+namespace ArmRipper.Core.Tests;
+
+public sealed class JobLoggerTests
+{
+    private static JobLogger CreateLogger(out string logPath)
+    {
+        var dir = Path.Combine(Path.GetTempPath(), $"joblogger-{Guid.NewGuid():N}");
+        var jobId = Guid.NewGuid().ToString("N");
+        logPath = Path.Combine(dir, $"arm_job_{jobId}.log");
+        return new JobLogger(jobId, dir, NullLogger.Instance);
+    }
+
+    [Fact]
+    public async Task ConcurrentLogs_AllLinesPreserved()
+    {
+        var logger = CreateLogger(out var logPath);
+
+        const int messageCount = 200;
+        var messages = Enumerable.Range(0, messageCount)
+            .Select(i => $"message-{i}-{new string('x', 100)}")
+            .ToArray();
+
+        await Task.WhenAll(messages.Select(m =>
+            Task.Run(() => logger.Log(LogLevel.Information, 0, m, null, (s, _) => s!))));
+
+        logger.Dispose();
+
+        var lines = await File.ReadAllLinesAsync(logPath);
+        var recovered = lines.Select(l => l.Split("] ").Last()).ToArray();
+
+        Assert.Equal(messageCount, lines.Length);
+        Assert.Equal(messages.OrderBy(m => m), recovered.OrderBy(m => m));
+    }
+
+    [Fact]
+    public void Log_AfterDispose_DoesNotThrow()
+    {
+        var logger = CreateLogger(out var logPath);
+        logger.Dispose();
+
+        var ex = Record.Exception(() =>
+            logger.Log(LogLevel.Information, 0, "late message", null, (s, _) => s!));
+
+        Assert.Null(ex);
+    }
+}