PowerDisplay: Make profile persistence atomic across processes

Serialize profile transactions across processes, publish saves atomically, and propagate persistence failures before migrating references. Also disambiguate duplicate profile names and validate profile-id IPC.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Copilot-Session: f1966791-4130-4447-94ff-09a2c3cacc30

Author: Yu Leng (from Dev Box)

src/modules/powerdisplay/PowerDisplay.Lib.UnitTests/ProfileStoreTests.cs

@@ -0,0 +1,242 @@
+// Copyright (c) Microsoft Corporation
+// The Microsoft Corporation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Text.Json;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using PowerDisplay.Models;
+
+namespace PowerDisplay.UnitTests;
+
+[TestClass]
+public class ProfileStoreTests
+{
+    private static readonly string[] ExpectedConcurrentProfileNames = { "First", "Second" };
+
+    private string _tempDir = string.Empty;
+    private string _profilesPath = string.Empty;
+    private string _mutexName = string.Empty;
+
+    [TestInitialize]
+    public void SetUp()
+    {
+        _tempDir = Path.Combine(Path.GetTempPath(), $"pd-profile-store-test-{Guid.NewGuid():N}");
+        Directory.CreateDirectory(_tempDir);
+        _profilesPath = Path.Combine(_tempDir, "profiles.json");
+        _mutexName = $@"Local\PowerToys_PowerDisplay_ProfileStore_Test_{Guid.NewGuid():N}";
+    }
+
+    [TestCleanup]
+    public void TearDown()
+    {
+        try
+        {
+            if (File.Exists(_profilesPath))
+            {
+                File.SetAttributes(_profilesPath, FileAttributes.Normal);
+            }
+
+            if (Directory.Exists(_tempDir))
+            {
+                Directory.Delete(_tempDir, recursive: true);
+            }
+        }
+        catch
+        {
+            // Best-effort cleanup.
+        }
+    }
+
+    [TestMethod]
+    public void LoadProfilesEnsuringIds_CorruptJson_DoesNotOverwriteSource()
+    {
+        const string corruptJson = "{not-json";
+        File.WriteAllText(_profilesPath, corruptJson);
+        var store = CreateStore();
+
+        Exception? exception = null;
+        try
+        {
+            store.LoadProfilesEnsuringIds();
+        }
+        catch (Exception ex)
+        {
+            exception = ex;
+        }
+
+        Assert.IsInstanceOfType<JsonException>(exception);
+        Assert.AreEqual(corruptJson, File.ReadAllText(_profilesPath));
+    }
+
+    [TestMethod]
+    public void LoadProfilesEnsuringIds_SaveFails_DoesNotReturnTransientIdsOrReplaceSource()
+    {
+        var profiles = new PowerDisplayProfiles();
+        profiles.Profiles.Add(MakeProfile("Legacy"));
+        var originalJson = JsonSerializer.Serialize(profiles, ProfileSerializationContext.Default.PowerDisplayProfiles);
+        File.WriteAllText(_profilesPath, originalJson);
+        File.SetAttributes(_profilesPath, FileAttributes.ReadOnly);
+        var store = CreateStore();
+
+        Exception? exception = null;
+        try
+        {
+            store.LoadProfilesEnsuringIds();
+        }
+        catch (Exception ex)
+        {
+            exception = ex;
+        }
+
+        Assert.IsNotNull(exception);
+        Assert.AreEqual(originalJson, File.ReadAllText(_profilesPath));
+        Assert.AreEqual(0, store.LoadProfiles().Profiles[0].Id);
+        Assert.IsFalse(Directory.EnumerateFiles(_tempDir, "*.tmp").Any());
+    }
+
+    [TestMethod]
+    public void AddOrUpdateProfile_WritesAtomicallyWithoutLeavingTemporaryFile()
+    {
+        var store = CreateStore();
+
+        store.AddOrUpdateProfile(MakeProfile("Gaming"));
+
+        var loaded = store.LoadProfiles();
+        Assert.AreEqual(1, loaded.Profiles.Count);
+        Assert.AreEqual(1, loaded.Profiles[0].Id);
+        Assert.IsFalse(Directory.EnumerateFiles(_tempDir, "*.tmp").Any());
+    }
+
+    [TestMethod]
+    public void AddOrUpdateProfile_SaveFails_RestoresIncomingProfileState()
+    {
+        var profiles = new PowerDisplayProfiles { NextId = 2 };
+        profiles.Profiles.Add(MakeProfile("Existing", id: 1));
+        var originalJson = JsonSerializer.Serialize(profiles, ProfileSerializationContext.Default.PowerDisplayProfiles);
+        File.WriteAllText(_profilesPath, originalJson);
+        File.SetAttributes(_profilesPath, FileAttributes.ReadOnly);
+        var incoming = MakeProfile("New");
+        incoming.LastModified = DateTime.UnixEpoch;
+        var store = CreateStore();
+
+        Exception? exception = null;
+        try
+        {
+            store.AddOrUpdateProfile(incoming);
+        }
+        catch (Exception ex)
+        {
+            exception = ex;
+        }
+
+        Assert.IsNotNull(exception);
+        Assert.AreEqual(0, incoming.Id);
+        Assert.AreEqual(DateTime.UnixEpoch, incoming.LastModified);
+        Assert.AreEqual(originalJson, File.ReadAllText(_profilesPath));
+        Assert.IsFalse(Directory.EnumerateFiles(_tempDir, "*.tmp").Any());
+    }
+
+    [TestMethod]
+    public void SaveProfiles_SaveFails_RestoresLastUpdated()
+    {
+        File.WriteAllText(_profilesPath, "{}");
+        File.SetAttributes(_profilesPath, FileAttributes.ReadOnly);
+        var profiles = new PowerDisplayProfiles { LastUpdated = DateTime.UnixEpoch };
+        var store = CreateStore();
+
+        Exception? exception = null;
+        try
+        {
+            store.SaveProfiles(profiles);
+        }
+        catch (Exception ex)
+        {
+            exception = ex;
+        }
+
+        Assert.IsNotNull(exception);
+        Assert.AreEqual(DateTime.UnixEpoch, profiles.LastUpdated);
+    }
+
+    [TestMethod]
+    public void AddOrUpdateProfile_TwoStoresSharingMutex_PreserveBothUpdates()
+    {
+        var firstStore = CreateStore();
+        var secondStore = CreateStore();
+        using var start = new ManualResetEventSlim();
+
+        var first = Task.Run(() =>
+        {
+            start.Wait();
+            firstStore.AddOrUpdateProfile(MakeProfile("First"));
+        });
+        var second = Task.Run(() =>
+        {
+            start.Wait();
+            secondStore.AddOrUpdateProfile(MakeProfile("Second"));
+        });
+
+        start.Set();
+        Task.WaitAll(first, second);
+
+        var loaded = firstStore.LoadProfiles();
+        Assert.AreEqual(2, loaded.Profiles.Count);
+        Assert.AreEqual(2, loaded.Profiles.Select(profile => profile.Id).Distinct().Count());
+        CollectionAssert.AreEquivalent(
+            ExpectedConcurrentProfileNames,
+            loaded.Profiles.Select(profile => profile.Name).ToArray());
+    }
+
+    [TestMethod]
+    public void UpdateProfiles_HoldsMutexAcrossLoadModifySave()
+    {
+        var firstStore = CreateStore();
+        var secondStore = CreateStore();
+        using var updateLoaded = new ManualResetEventSlim();
+        using var continueUpdate = new ManualResetEventSlim();
+
+        var first = Task.Run(() =>
+            firstStore.UpdateProfiles(profiles =>
+            {
+                updateLoaded.Set();
+                continueUpdate.Wait();
+                profiles.SetProfile(MakeProfile("First"));
+                return true;
+            }));
+
+        Assert.IsTrue(updateLoaded.Wait(TimeSpan.FromSeconds(5)));
+        var second = Task.Run(() => secondStore.AddOrUpdateProfile(MakeProfile("Second")));
+        continueUpdate.Set();
+        Task.WaitAll(first, second);
+
+        var loaded = firstStore.LoadProfiles();
+        Assert.AreEqual(2, loaded.Profiles.Count);
+        CollectionAssert.AreEquivalent(
+            ExpectedConcurrentProfileNames,
+            loaded.Profiles.Select(profile => profile.Name).ToArray());
+    }
+
+    private ProfileStore CreateStore()
+    {
+        return new ProfileStore(_profilesPath, _mutexName, TimeSpan.FromSeconds(5));
+    }
+
+    private static PowerDisplayProfile MakeProfile(string name, int id = 0)
+    {
+        return new PowerDisplayProfile(
+            name,
+            new List<ProfileMonitorSetting>
+            {
+                new ProfileMonitorSetting("MON1", 50, null, null, null),
+            })
+        {
+            Id = id,
+        };
+    }
+}

src/modules/powerdisplay/PowerDisplay.Lib/Services/ProfileService.cs

@@ -2,6 +2,7 @@
 // The Microsoft Corporation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using System;
 using PowerDisplay.Models;
 using ModelsProfileHelper = PowerDisplay.Models.ProfileHelper;
 
@@ -17,7 +18,13 @@ public static class ProfileService
         /// <inheritdoc cref="ModelsProfileHelper.LoadProfiles"/>
         public static PowerDisplayProfiles LoadProfiles() => ModelsProfileHelper.LoadProfiles();
 
+        /// <inheritdoc cref="ModelsProfileHelper.LoadProfilesEnsuringIds"/>
+        public static PowerDisplayProfiles LoadProfilesEnsuringIds() => ModelsProfileHelper.LoadProfilesEnsuringIds();
+
         /// <inheritdoc cref="ModelsProfileHelper.SaveProfiles"/>
         public static bool SaveProfiles(PowerDisplayProfiles profiles) => ModelsProfileHelper.SaveProfiles(profiles);
+
+        /// <inheritdoc cref="ModelsProfileHelper.UpdateProfiles"/>
+        public static bool UpdateProfiles(Func<PowerDisplayProfiles, bool> update) => ModelsProfileHelper.UpdateProfiles(update);
     }
 }

src/modules/powerdisplay/PowerDisplay.Models/PowerDisplay.Models.csproj

@@ -17,6 +17,9 @@
   <PropertyGroup>
     <IsAotCompatible>true</IsAotCompatible>
   </PropertyGroup>
+  <ItemGroup>
+    <InternalsVisibleTo Include="PowerDisplay.Lib.UnitTests" />
+  </ItemGroup>
   <ItemGroup>
     <EmbeddedResource Include="BuiltInMonitorBlacklist.json" />
   </ItemGroup>