日志审计信息

Question

我必须实现一个审计系统，在这个系统中，用户必须提供执行某个操作所需的理由。当他提供理由时，他可以自由地表演一段时间。操作的每一次执行都需要在某个地方进行记录。

我使用延拓传递方式实现了它，它允许我干净地处理原子权限检查和操作日志记录。

public class AuditLogger
{
   private readonly TimeSpan permissionDuration;
   private readonly IAuditDatabase auditDatabase;

   private DateTime permissionExpiry = DateTime.MinValue;
   private string accessReason;

   public AuditLogger(TimeSpan permissionDuration, IAuditDatabase auditDatabase)
   {
       this.permissionDuration = permissionDuration;
       this.auditDatabase = auditDatabase;
   }

   private bool CheckPermission()
   {
       return DateTime.UTCNow < permissionExpiry;
   }

   public void SetAccessReason(string reason)
   {
       reason = reason;
       permissionExpiry = DateTime.UTCNow.Add(permissionDuration);
   }

   public void LogAccessAndExecuteOperation(Action operation, Action onPermissionExpired, Action<Exception> onError)
   {
       if(CheckPermission())
           onPermissionExpired();
       try
       {
           auditDatabase.Log(reason);
           operation();            
       }
       catch(Exception exception)
       {
           onError(exception);
       }
   }    
}

你觉得那个怎么样？

这里是一些客户端代码，以显示应该如何使用它。

public static void Main(string[] args)
{
    var auditLogger = new AuditLogger(TimeSpan.FromMinutes(15), new AuditingDatabase);
    var reason = args[0]; // Let's assume the user tells us what he needs to do at startup
    auditLogger.SetAccessReason(reason);

    // Now the user keeps doing lots of things    
    while(1)
    {
        auditLogger.LogAccessAndExecuteOperation(
            () => { /* doing nothing here */ Thread.Sleep(1000); },
            () => {
                Console.WriteLine("Time's up. Can you please tell us again what you need to do?");
                reason = Console.ReadLine();
                auditLogger.SetAccessReason(reason);                
            },
            exeption => Console.WriteLine(exception)
            );
    }
}

Answer 1

不幸的是，该类违反了单一责任原则，因为它必须处理日志记录和到期的访问。

您可以在这里使用装饰图案并将授权和日志记录拆分为不同的类，如下所示：

public interface IAccessWidget
{
   string AccessReason { get; }
   void SetAccessReason(string reason);
   void ExecuteOperation(Action operation, Action onPermissionExpired, Action<Exception> onError);
}

public class AccessWidget
{
    private readonly TimeSpan _permissionDuration;
    private DateTime _permissionExpiry = DateTime.MinValue;

    public string AccessReason { get; private set; }

    public AccessWidget(TimeSpan permissionDuration)
    {
        _permissionDuration = permissionDuration;
    }

    private bool CheckPermission()
    {
        return DateTime.UtcNow < _permissionExpiry;
    }

    public void SetAccessReason(string reason)
    {
        AccessReason = reason;
        _permissionExpiry = DateTime.UtcNow.Add(_permissionDuration);
    }

    public void ExecuteOperation(Action operation, Action onPermissionExpired, Action<Exception> onError)
    {
        if(CheckPermission())
            onPermissionExpired();
        try
        {
            operation();
        }
        catch(Exception exception)
        {
            onError(exception);
        }
    }
}

public class LoggingAccessWidget : IAccessWidget
{
    private readonly IAuditDatabase _auditDatabase;
    private readonly IAccessWidget _widget;

    public string AccessReason { get { return _widget.AccessReason; } }

    public LoggingAccessWidget(IAccessWidget widget, IAuditDatabase auditDatabase)
    {
        _widget = widget;
        _auditDatabase = auditDatabase;
    }

    public void SetAccessReason(string reason)
    {
       _widget.SetAccessReason(reason);
    }

    public void ExecuteOperation(Action operation, Action onPermissionExpired, Action<Exception> onError)
    {
        _auditDatabase.Log(_widget.AccessReason);
        _widget.ExecuteOperation(operation, onPermissionExpired, onError);
    }
}