c# - 检查异常类型性能

Question

我有一个方法可以检查传入的异常并返回一个 bool 值。

目前我的实现是这样的

private bool ExceptionShouldNotify(Exception e)
{
    return
    e is FirstCustomException  ||
    e is SecondCustomException ||
    e is ThirdCustomException  ||
    e is FourthCustomException ||
    e is FifthCustomException  ||
    e is SixthCustomException  ||
    e is SeventhCustomException;
}

然而，使用字典查找比多个 OR 语句和 is 检查在性能方面更好吗？

像这样:

private bool ExceptionShouldNotify(Exception e)
{
    var dict = new Dictionary<String, int> {
        { "FirstCustomException",   1 },
        { "SecondCustomException",  1 },
        { "ThirdCustomException",   1 },
        { "FourthCustomException",  1 },
        { "FifthCustomException",   1 },
        { "SixthCustomException",   1 },
        { "SeventhCustomException", 1 }
    };

    return dict.ContainsKey(e.GetType().Name);
}

Answer 1

硬编码(第一种解决方案)是一种不好的做法，这就是我投票支持字典(第二种解决方案)的原因，但我建议采用不同的实现方式:

   // HashSet - you don't use Value in the Dictionary, but Key
   // Type - we compare types, not their names
   private static HashSet<Type> s_ExceptionsToNotify = new HashSet<Type>() {
     typeof(FirstCustomException),
     typeof(SecondCustomException),
     ...
   };   

   // static: you don't use "this" in the method
   private static bool ExceptionShouldNotify(Exception e) {
     return s_ExceptionsToNotify.Contains(e.GetType());
   }

捕获异常(包括堆栈跟踪)你已经有很大的开销；这就是为什么性能(7 个简单比较与计算哈希)不是上下文中的主要问题