feat(update): update the backend like nodes via quadlet restart [CI]

backend/src/MoShiro.Backend.Storage.Sqlite/BackendUpdateFiles.cs

@@ -1,89 +0,0 @@
-using System.Globalization;
-using System.Text;
-using System.Text.Json;
-using MoShiro.Backend.Application;
-using MoShiro.Protocol;
-
-namespace MoShiro.Backend.Storage.Sqlite;
-
-/// <summary>Backend 到宿主机的文件信箱。状态卷只读挂载，业务进程改写不了验签和安装结果。</summary>
-public sealed class BackendUpdateFiles : IBackendUpdateFiles
-{
-    private readonly string _requests;
-    private readonly string _status;
-
-    public BackendUpdateFiles(BackendOptions options)
-    {
-        _requests = Path.GetFullPath(options.BackendUpdateDirectory ?? Path.Combine(options.DataDirectory, "update"));
-        _status = Path.GetFullPath(options.BackendUpdateStatusDirectory ?? Path.Combine(options.DataDirectory, "update-status"));
-    }
-
-    public async ValueTask WriteOfferAsync(string manifest, string signature, CancellationToken ct)
-    {
-        await WriteAsync("offer.manifest", manifest, ct);
-        await WriteAsync("offer.sig", signature, ct);
-    }
-
-    public async ValueTask<UpdateStatus?> ReadStatusAsync(CancellationToken ct)
-    {
-        string? json = await ReadAsync(Path.Combine(_status, "status.json"), 4096, ct);
-        if (json is null)
-        {
-            return null;
-        }
-
-        try
-        {
-            return JsonSerializer.Deserialize(json, MoShiroJsonContext.Default.UpdateStatus);
-        }
-        catch (JsonException)
-        {
-            return null;
-        }
-    }
-
-    public async ValueTask<long?> ReadRequestAsync(CancellationToken ct)
-    {
-        string? request = await ReadAsync(Path.Combine(_requests, "apply.request"), 64, ct);
-        return long.TryParse(request, NumberStyles.None, CultureInfo.InvariantCulture, out long seq) ? seq : null;
-    }
-
-    public ValueTask RequestAsync(long seq, CancellationToken ct) => WriteAsync("apply.request", seq.ToString(CultureInfo.InvariantCulture), ct);
-
-    private async ValueTask WriteAsync(string name, string value, CancellationToken ct)
-    {
-        Directory.CreateDirectory(_requests);
-        string path = Path.Combine(_requests, name);
-        string temporary = Path.Combine(_requests, $".{name}.{Guid.NewGuid():N}");
-        try
-        {
-            await File.WriteAllTextAsync(temporary, value, new UTF8Encoding(false), ct);
-            File.Move(temporary, path, overwrite: true);
-        }
-        finally
-        {
-            if (File.Exists(temporary))
-            {
-                File.Delete(temporary);
-            }
-        }
-    }
-
-    private static async ValueTask<string?> ReadAsync(string path, int limit, CancellationToken ct)
-    {
-        try
-        {
-            var file = new FileInfo(path);
-            if (!file.Exists || file.LinkTarget is not null || file.Length > limit)
-            {
-                return null;
-            }
-
-            return await File.ReadAllTextAsync(path, ct);
-        }
-        catch (IOException)
-        {
-            return null; // 更新器正做原子替换，下一次读取再试
-        }
-    }
-}

backend/src/MoShiro.Backend.Storage.Sqlite/SqliteDatabaseBackup.cs

@@ -0,0 +1,37 @@
+using Microsoft.Data.Sqlite;
+using MoShiro.Backend.Application;
+
+namespace MoShiro.Backend.Storage.Sqlite;
+
+/// <summary>用 <c>VACUUM INTO</c> 写一份一致的数据库副本：不停服务，WAL 里还没合并的写入也在里面。</summary>
+public sealed class SqliteDatabaseBackup : IDatabaseBackup
+{
+    private readonly SqliteDatabase _database;
+
+    public SqliteDatabaseBackup(SqliteDatabase database)
+    {
+        _database = database;
+    }
+
+    public ValueTask<string> BackupAsync(string directory, string name, CancellationToken ct)
+    {
+        Directory.CreateDirectory(directory);
+        string path = Path.Combine(directory, name);
+        try
+        {
+            _database.Read(connection =>
+            {
+                using SqliteCommand command = connection.CreateCommand();
+                command.CommandText = "VACUUM INTO $path";
+                command.Parameters.AddWithValue("$path", path);
+                return command.ExecuteNonQuery();
+            });
+        }
+        catch (SqliteException ex)
+        {
+            throw new IOException("the database backup failed: " + ex.Message, ex);
+        }
+
+        return ValueTask.FromResult(path);
+    }
+}

backend/src/MoShiro.Backend.Storage.Sqlite/StorageServiceCollectionExtensions.cs

@@ -27,7 +27,7 @@ public static class StorageServiceCollectionExtensions
         services.AddSingleton<IRawStore, SqliteRawStore>();
         services.AddSingleton<IMetricStore, SqliteMetricStore>();
         services.AddSingleton<IStorageHealth, SqliteStorageHealth>();
-        services.AddSingleton<IBackendUpdateFiles, BackendUpdateFiles>();
+        services.AddSingleton<IDatabaseBackup, SqliteDatabaseBackup>();
         return services;
     }
 }