使用过度的代表为性能的一个坏主意？ [英] Is using delegates excessively a bad idea for performance?

问题描述

考虑以下code：

if (IsDebuggingEnabled) { 
   instance.Log(GetDetailedDebugInfo()); 
}

GetDetailedDebugInfo（）可能是一个昂贵的方法，所以我们只需要调用它，如果我们在调试模式下正在运行。

GetDetailedDebugInfo() may be an expensive method, so we only want to call it if we're running in debug mode.

现在，清洁的替代方法是code是这样的：

Now, the cleaner alternative is to code something like this:

instance.Log(() => GetDetailedDebugInfo());

在哪里.LOG（）的定义，如：

Where .Log() is defined such as:

public void Log(Func<string> getMessage)
{
    if (IsDebuggingEnabled) 
    {
        LogInternal(getMessage.Invoke());
    }
}

我关心的是性能，preliminary测试不显示第二种情况是特别贵，但我不希望碰到任何的意外，如果负荷增加。

My concern is with performance, preliminary testing doesn't show the second case to be particularly more expensive, but I don't want to run into any surprises if load increases.

哦，请不要暗示条件编译，因为它并不适用于这种情况。

Oh, and please don't suggest conditional compilation because it doesn't apply to this case.

（PS：我直接在StackOverflow上写的code提问textarea的，所以不要怪我，如果有细微的错误，它并不能编译，你明白了吧：）

(P.S.: I wrote the code directly in the StackOverflow Ask a Question textarea so don't blame me if there are subtle bugs and it doesn't compile, you get the point :)

推荐答案

我希望了解有关在这种情况下的表现有些文档，但似乎我的一切都是关于如何提高我的code建议...似乎没有人读过我的PS - 无分你

I was hoping for some documentation regarding performance in such cases, but it seems that all I got were suggestions on how to improve my code... No one seems to have read my P.S. - no points for you.

所以我写了一个简单的测试案例：

So I wrote a simple test case:

    public static bool IsDebuggingEnabled { get; set; }


    static void Main(string[] args)
    {
        for (int j = 0; j <= 10; j++)
        {
            Stopwatch sw = Stopwatch.StartNew();
            for (int i = 0; i <= 15000; i++)
            {
                Log(GetDebugMessage);
                if (i % 1000 == 0) IsDebuggingEnabled = !IsDebuggingEnabled;
            }
            sw.Stop();
            Console.WriteLine(sw.ElapsedMilliseconds);
        }

        Console.ReadLine();
        for (int j = 0; j <= 10; j++)
        {
            Stopwatch sw = Stopwatch.StartNew();
            for (int i = 0; i <= 15000; i++)
            {
                if (IsDebuggingEnabled) GetDebugMessage();
                if (i % 1000 == 0) IsDebuggingEnabled = !IsDebuggingEnabled;
            }
            sw.Stop();
            Console.WriteLine(sw.ElapsedMilliseconds);
        }
        Console.ReadLine();
    }

    public static string GetDebugMessage()
    {
        StringBuilder sb = new StringBuilder(100);
        Random rnd = new Random();
        for (int i = 0; i < 100; i++)
        {
            sb.Append(rnd.Next(100, 150));
        }
        return sb.ToString();
    }

    public static void Log(Func<string> getMessage)
    {
        if (IsDebuggingEnabled)
        {
            getMessage();
        }
    }

计时似乎是完全相同的两个版本之间的相同。 我得到145毫秒，在第一种情况下，145毫秒，在第二种情况下

Timings seem to be exactly the same between the two versions. I get 145 ms in the first case, and 145 ms in the second case

看起来像我回答我自己的问题。

Looks like I answered my own question.

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