使用SQliteAsyncConnection与UnitOfWork；存储库模式

我需要为windows 8应用程序实现一个完全异步的架构，我使用SQLite for winRT&数据层中的SQLite.Net。

到目前为止我所做的：

DAL-

上下文：

public interface IContext
    {
        Task InitializeDatabase();
        SQLiteAsyncConnection GetAsyncConnection();
    }
public class SQLiteAsyncContext : IContext
    {
        private SQLiteAsyncConnection _context;
        private String  _dBPath;
        public SQLiteAsyncContext()
        {
            this._dBPath = Path.Combine(
                Windows.Storage.ApplicationData.Current.LocalFolder.Path, "DBName");
            this._context = new SQLiteAsyncConnection(_dBPath);
        }
        public async Task InitializeDatabase()
        {
            await _context.CreateTableAsync<User>();
        }
        public SQLiteAsyncConnection GetAsyncConnection()
        {
            return _context;
        }
    }

通用存储库：

    public interface IAsyncRepository<T> where T : class
        {
            Task<int> AddAsync(T entity);
            Task<int> UpdateAsync(T entity);
            Task<int> RemoveAsync(T entity);
            Task<IList<T>> GetAllAsync();
            Task<IList<T>> GetBy(System.Linq.Expressions.Expression<Func<T, bool>> predicate);
            Task SaveChanges();
        }
    public class AsyncRepository<T> : IAsyncRepository<T> where T : class, new()
        {
            private SQLiteAsyncConnection _context;
            public AsyncRepository(IContext _context)
            {
                this._context = _context.GetAsyncConnection();
            }
            public async Task<int> AddAsync(T entity)
            {
                return await _context.InsertAsync(entity);
            }
            public async Task<int> UpdateAsync(T entity)
            {
                return await _context.UpdateAsync(entity);
            }
            public async Task<int> RemoveAsync(T entity)
            {
                return await _context.DeleteAsync(entity);
            }
            public async Task<IList<T>> GetAllAsync()
            {
                return await _context.Table<T>().ToListAsync();
            }
            public async Task<IList<T>> GetBy(System.Linq.Expressions.Expression<Func<T, bool>> predicate)
            {
                return await _context.Table<T>().Where(predicate).ToListAsync();
            }
            public Task SaveChanges()
            {
            throw new NotImplementedException();
            }
        }

BL-

    public interface IAsyncServices<T> where T : class
    {
        Task<int> AddAsync(T entity);
        Task<int> UpdateAsync(T entity);
        Task<int> RemoveAsync(T entity);
        Task<IList<T>> GetAllAsync();
        Task<IList<T>> GetBy(System.Linq.Expressions.Expression<Func<T, bool>> predicate);
    }
public class AsyncUserService : IAsyncServices<User>
    {
        private readonly IAsyncRepository<User> _asyncUserRepository;
        public AsyncUserService(IAsyncRepository<User> _asyncUserRepository)
        {
            this._asyncUserRepository = _asyncUserRepository;
        }
        public async Task<int> AddAsync(User entity)
        {
            return await _asyncUserRepository.AddAsync(entity);
        }
        public async Task<int> UpdateAsync(User entity)
        {
            return await _asyncUserRepository.UpdateAsync(entity);
        }
        public async Task<int> RemoveAsync(User entity)
        {
            return await _asyncUserRepository.RemoveAsync(entity);
        }
        public async Task<IList<User>> GetAllAsync()
        {
            return await _asyncUserRepository.GetAllAsync();
        }
        public async Task<IList<User>> GetBy(Expression<Func<User, bool>> predicate)
        {
            return await _asyncUserRepository.GetBy(predicate);
        }
    }

我有一些问题：

1. 是否可以使用SQliteAsyncConnection实现UnitOfWork模式
2. 如何执行提交&在存储库中回滚
3. 有什么需要改进的吗

提前感谢。