config: save asynchronously to prevent hitches

Dalamud/Configuration/Internal/DalamudConfiguration.cs

@@ -4,6 +4,7 @@
 using System.IO;
 using System.Linq;
 using System.Runtime.InteropServices;
+using System.Threading.Tasks;
 
 using Dalamud.Game.Text;
 using Dalamud.Interface;
@@ -45,6 +46,8 @@ internal sealed class DalamudConfiguration : IInternalDisposableService
     [JsonIgnore]
     private bool isSaveQueued;
 
+    private Task? writeTask;
+
     /// <summary>
     /// Delegate for the <see cref="DalamudConfiguration.DalamudConfigurationSaved"/> event that occurs when the dalamud configuration is saved.
     /// </summary>
@@ -560,6 +563,9 @@ void IInternalDisposableService.DisposeService()
     {
         // Make sure that we save, if a save is queued while we are shutting down
         this.Update();
+
+        // Wait for the write task to finish
+        this.writeTask?.Wait();
     }
 
     /// <summary>
@@ -614,8 +620,22 @@ private void Save()
         if (this.configPath is null)
             throw new InvalidOperationException("configPath is not set.");
 
-        Service<ReliableFileStorage>.Get().WriteAllText(
-            this.configPath, JsonConvert.SerializeObject(this, SerializerSettings));
+        // Wait for previous write to finish
+        this.writeTask?.Wait();
+
+        this.writeTask = Task.Run(() =>
+        {
+            Service<ReliableFileStorage>.Get().WriteAllText(
+                this.configPath,
+                JsonConvert.SerializeObject(this, SerializerSettings));
+        }).ContinueWith(t =>
+        {
+            if (t.IsFaulted)
+            {
+                Log.Error(t.Exception, "Failed to save DalamudConfiguration to {Path}", this.configPath);
+            }
+        });
+
         this.DalamudConfigurationSaved?.Invoke(this);
     }
 }

Dalamud/Interface/Internal/Windows/Data/DataWindow.cs

@@ -60,6 +60,7 @@ internal class DataWindow : Window, IDisposable
         new ToastWidget(),
         new UiColorWidget(),
         new UldWidget(),
+        new VfsWidget(),
     };
 
     private readonly IOrderedEnumerable<IDataWindowWidget> orderedModules;

Dalamud/Interface/Internal/Windows/Data/Widgets/VfsWidget.cs

@@ -0,0 +1,102 @@
+using System.Diagnostics;
+using System.IO;
+
+using Dalamud.Configuration.Internal;
+using Dalamud.Storage;
+using ImGuiNET;
+using Serilog;
+
+namespace Dalamud.Interface.Internal.Windows.Data.Widgets;
+
+/// <summary>
+/// Widget for displaying configuration info.
+/// </summary>
+internal class VfsWidget : IDataWindowWidget
+{
+    private int numBytes = 1024;
+    private int reps = 1;
+
+    /// <inheritdoc/>
+    public string[]? CommandShortcuts { get; init; } = { "vfs" };
+
+    /// <inheritdoc/>
+    public string DisplayName { get; init; } = "VFS Performance";
+
+    /// <inheritdoc/>
+    public bool Ready { get; set; }
+
+    /// <inheritdoc/>
+    public void Load()
+    {
+        this.Ready = true;
+    }
+
+    /// <inheritdoc/>
+    public void Draw()
+    {
+        var service = Service<ReliableFileStorage>.Get();
+        var dalamud = Service<Dalamud>.Get();
+
+        ImGui.InputInt("Num bytes", ref this.numBytes);
+        ImGui.InputInt("Reps", ref this.reps);
+
+        var path = Path.Combine(dalamud.StartInfo.WorkingDirectory!, "test.bin");
+
+        if (ImGui.Button("Write"))
+        {
+            Log.Information("=== WRITING ===");
+            var data = new byte[this.numBytes];
+            var stopwatch = new Stopwatch();
+            var acc = 0L;
+
+            for (var i = 0; i < this.reps; i++)
+            {
+                stopwatch.Restart();
+                service.WriteAllBytes(path, data);
+                stopwatch.Stop();
+                acc += stopwatch.ElapsedMilliseconds;
+                Log.Information("Turn {Turn} took {Ms}ms", i, stopwatch.ElapsedMilliseconds);
+            }
+
+            Log.Information("Took {Ms}ms in total", acc);
+        }
+
+        if (ImGui.Button("Read"))
+        {
+            Log.Information("=== READING ===");
+            var stopwatch = new Stopwatch();
+            var acc = 0L;
+
+            for (var i = 0; i < this.reps; i++)
+            {
+                stopwatch.Restart();
+                service.ReadAllBytes(path);
+                stopwatch.Stop();
+                acc += stopwatch.ElapsedMilliseconds;
+                Log.Information("Turn {Turn} took {Ms}ms", i, stopwatch.ElapsedMilliseconds);
+            }
+
+            Log.Information("Took {Ms}ms in total", acc);
+        }
+
+        if (ImGui.Button("Test Config"))
+        {
+            var config = Service<DalamudConfiguration>.Get();
+
+            Log.Information("=== READING ===");
+            var stopwatch = new Stopwatch();
+            var acc = 0L;
+
+            for (var i = 0; i < this.reps; i++)
+            {
+                stopwatch.Restart();
+                config.ForceSave();
+                stopwatch.Stop();
+                acc += stopwatch.ElapsedMilliseconds;
+                Log.Information("Turn {Turn} took {Ms}ms", i, stopwatch.ElapsedMilliseconds);
+            }
+
+            Log.Information("Took {Ms}ms in total", acc);
+        }
+    }
+}