refactor: saving time about repo's shared settings (#2108)

- Save repo's settings only when user changed it from `Repository Configuration` dialog and is closing this dialog
- Never unload repo's settings (it is very small in memory)

Author: love-linger

src/Models/RepositorySettings.cs

@@ -1,6 +1,10 @@
+using System;
 using System.Collections.Generic;
 using System.IO;
+using System.Security.Cryptography;
+using System.Text;
 using System.Text.Json;
+using System.Threading.Tasks;
 
 using Avalonia.Collections;
 
@@ -68,15 +72,12 @@ public AvaloniaList<CustomAction> CustomActions
             set;
         } = [];
 
-        public static RepositorySettings Get(string repo, string gitCommonDir)
+        public static RepositorySettings Get(string gitCommonDir)
         {
             var fileInfo = new FileInfo(Path.Combine(gitCommonDir, "sourcegit.settings"));
             var fullpath = fileInfo.FullName;
             if (_cache.TryGetValue(fullpath, out var setting))
-            {
-                setting._usedBy.Add(repo);
                 return setting;
-            }
 
             if (!File.Exists(fullpath))
             {
@@ -96,28 +97,26 @@ public static RepositorySettings Get(string repo, string gitCommonDir)
             }
 
             setting._file = fullpath;
-            setting._usedBy.Add(repo);
+            setting._orgHash = HashContent(JsonSerializer.Serialize(setting, JsonCodeGen.Default.RepositorySettings));
             _cache.Add(fullpath, setting);
             return setting;
         }
 
-        public void TryUnload(string repo)
+        public async Task SaveAsync()
         {
-            _usedBy.Remove(repo);
-
-            if (_usedBy.Count == 0)
+            try
             {
-                try
-                {
-                    using var stream = File.Create(_file);
-                    JsonSerializer.Serialize(stream, this, JsonCodeGen.Default.RepositorySettings);
-                }
-                catch
+                string content = JsonSerializer.Serialize(this, JsonCodeGen.Default.RepositorySettings);
+                string hash = HashContent(content);
+                if (!hash.Equals(_orgHash, StringComparison.Ordinal))
                 {
-                    // Ignore save errors
+                    await File.WriteAllTextAsync(_file, content);
+                    _orgHash = hash;
                 }
-
-                _cache.Remove(_file);
+            }
+            catch
+            {
+                // Ignore save errors
             }
         }
 
@@ -167,8 +166,17 @@ public void MoveCustomActionDown(CustomAction act)
                 CustomActions.Move(idx + 1, idx);
         }
 
+        private static string HashContent(string source)
+        {
+            var hash = MD5.HashData(Encoding.Default.GetBytes(source));
+            var builder = new StringBuilder(hash.Length * 2);
+            foreach (var c in hash)
+                builder.Append(c.ToString("x2"));
+            return builder.ToString();
+        }
+
         private static Dictionary<string, RepositorySettings> _cache = new();
         private string _file = string.Empty;
-        private HashSet<string> _usedBy = new();
+        private string _orgHash = string.Empty;
     }
 }

src/ViewModels/Repository.cs

@@ -426,10 +426,10 @@ public Repository(bool isBare, string path, string gitDir)
             GitDir = gitDir.Replace('\\', '/').TrimEnd('/');
 
             var commonDirFile = Path.Combine(GitDir, "commondir");
-            _isWorktree = GitDir.IndexOf("/worktrees/", StringComparison.Ordinal) > 0 &&
+            var isWorktree = GitDir.IndexOf("/worktrees/", StringComparison.Ordinal) > 0 &&
                           File.Exists(commonDirFile);
 
-            if (_isWorktree)
+            if (isWorktree)
             {
                 var commonDir = File.ReadAllText(commonDirFile).Trim();
                 if (!Path.IsPathRooted(commonDir))
@@ -445,7 +445,7 @@ public Repository(bool isBare, string path, string gitDir)
 
         public void Open()
         {
-            _settings = Models.RepositorySettings.Get(FullPath, _gitCommonDir);
+            _settings = Models.RepositorySettings.Get(_gitCommonDir);
             _uiStates = Models.RepositoryUIStates.Load(GitDir);
 
             try
@@ -484,7 +484,6 @@ public void Close()
             SelectedView = null; // Do NOT modify. Used to remove exists widgets for GC.Collect
             Logs.Clear();
 
-            _settings.TryUnload(FullPath);
             _uiStates.Unload(_workingCopy.CommitMessage);
 
             if (_cancellationRefreshBranches is { IsCancellationRequested: false })
@@ -1775,6 +1774,9 @@ private void AutoFetchByTimer(object sender)
 
         private async Task AutoFetchOnUIThread()
         {
+            if (_uiStates == null)
+                return;
+
             CommandLog log = null;
 
             try
@@ -1829,7 +1831,6 @@ private async Task AutoFetchOnUIThread()
             log?.Complete();
         }
 
-        private readonly bool _isWorktree = false;
         private readonly string _gitCommonDir = null;
         private Models.RepositorySettings _settings = null;
         private Models.RepositoryUIStates _uiStates = null;

src/ViewModels/RepositoryConfigure.cs

@@ -295,6 +295,7 @@ public async Task SaveAsync()
             await SetIfChangedAsync("fetch.prune", EnablePruneOnFetch ? "true" : "false", "false");
 
             await ApplyIssueTrackerChangesAsync();
+            await _repo.Settings.SaveAsync();
         }
 
         private async Task SetIfChangedAsync(string key, string value, string defValue)
@@ -359,8 +360,8 @@ private async Task ApplyIssueTrackerChangesAsync()
             }
         }
 
-        private readonly Repository _repo = null;
-        private readonly Dictionary<string, string> _cached = null;
+        private readonly Repository _repo;
+        private readonly Dictionary<string, string> _cached;
         private string _httpProxy;
         private Models.CommitTemplate _selectedCommitTemplate = null;
         private Models.IssueTracker _selectedIssueTracker = null;