將不確定變為確定~老趙寫的CodeTimer是代碼性能測試的利器

首先，非常感謝趙老大的CodeTimer，它讓我們更好的了解到代碼執行的性能，從而可以讓我們從性能的角度來考慮問題，有些東西可能我們認為是這樣的，但經理測試并非如何，這正應了我之前的那名話：“機器最能證明一切”！

費話就不說了，看代碼吧：

  1     /// <summary>2     /// 執行代碼規范3     /// </summary>4     public interface IAction5     {6         void Action();7     }8 9     /// <summary>10     /// 老趙的性能測試工具11     /// </summary>12     public static class CodeTimer13     {14         [DllImport("kernel32.dll", SetLastError = true)]15         static extern bool GetThreadTimes(IntPtr hThread, out long lpCreationTime, out long lpExitTime, out long lpKernelTime, out long lpUserTime);16 17         [DllImport("kernel32.dll")]18         static extern IntPtr GetCurrentThread();19         public delegate void ActionDelegate();20         private static long GetCurrentThreadTimes()21         {22             long l;23             long kernelTime, userTimer;24             GetThreadTimes(GetCurrentThread(), out l, out l, out kernelTime, out userTimer);25             return kernelTime + userTimer;26         }27         static CodeTimer()28         {29             Process.GetCurrentProcess().PriorityClass = ProcessPriorityClass.High;30             Thread.CurrentThread.Priority = ThreadPriority.Highest;31         }32         public static void Time(string name, int iteration, ActionDelegate action)33         {34             if (String.IsNullOrEmpty(name))35             {36                 return;37             }38             if (action == null)39             {40                 return;41             }42 43             //1. Print name44             ConsoleColor currentForeColor = Console.ForegroundColor;45             Console.ForegroundColor = ConsoleColor.Yellow;46             Console.WriteLine(name);47 48             // 2. Record the latest GC counts49             //GC.Collect(GC.MaxGeneration, GCCollectionMode.Forced);50             GC.Collect(GC.MaxGeneration);51             int[] gcCounts = new int[GC.MaxGeneration + 1];52             for (int i = 0; i <= GC.MaxGeneration; i++)53             {54                 gcCounts[i] = GC.CollectionCount(i);55             }56 57             // 3. Run action58             Stopwatch watch = new Stopwatch();59             watch.Start();60             long ticksFst = GetCurrentThreadTimes(); //100 nanosecond one tick61             for (int i = 0; i < iteration; i++) action();62             long ticks = GetCurrentThreadTimes() - ticksFst;63             watch.Stop();64 65             // 4. Print CPU66             Console.ForegroundColor = currentForeColor;67             Console.WriteLine("\tTime Elapsed:\t\t" +68                watch.ElapsedMilliseconds.ToString("N0") + "ms");69             Console.WriteLine("\tTime Elapsed (one time):" +70                (watch.ElapsedMilliseconds / iteration).ToString("N0") + "ms");71             Console.WriteLine("\tCPU time:\t\t" + (ticks * 100).ToString("N0")72                + "ns");73             Console.WriteLine("\tCPU time (one time):\t" + (ticks * 100 /74                iteration).ToString("N0") + "ns");75 76             // 5. Print GC77             for (int i = 0; i <= GC.MaxGeneration; i++)78             {79                 int count = GC.CollectionCount(i) - gcCounts[i];80                 Console.WriteLine("\tGen " + i + ": \t\t\t" + count);81             }82             Console.WriteLine();83         }84 85 86 87         public static void Time(string name, int iteration, IAction action)88         {89             if (String.IsNullOrEmpty(name))90             {91                 return;92             }93 94             if (action == null)95             {96                 return;97             }98 99             //1. Print name
100             ConsoleColor currentForeColor = Console.ForegroundColor;
101             Console.ForegroundColor = ConsoleColor.Yellow;
102             Console.WriteLine(name);
103 
104             // 2. Record the latest GC counts
105             //GC.Collect(GC.MaxGeneration, GCCollectionMode.Forced);
106             GC.Collect(GC.MaxGeneration);
107             int[] gcCounts = new int[GC.MaxGeneration + 1];
108             for (int i = 0; i <= GC.MaxGeneration; i++)
109             {
110                 gcCounts[i] = GC.CollectionCount(i);
111             }
112 
113             // 3. Run action
114             Stopwatch watch = new Stopwatch();
115             watch.Start();
116             long ticksFst = GetCurrentThreadTimes(); //100 nanosecond one tick
117             for (int i = 0; i < iteration; i++) action.Action();
118             long ticks = GetCurrentThreadTimes() - ticksFst;
119             watch.Stop();
120 
121             // 4. Print CPU
122             Console.ForegroundColor = currentForeColor;
123             Console.WriteLine("\tTime Elapsed:\t\t" +
124                watch.ElapsedMilliseconds.ToString("N0") + "ms");
125             Console.WriteLine("\tTime Elapsed (one time):" +
126                (watch.ElapsedMilliseconds / iteration).ToString("N0") + "ms");
127             Console.WriteLine("\tCPU time:\t\t" + (ticks * 100).ToString("N0")
128                 + "ns");
129             Console.WriteLine("\tCPU time (one time):\t" + (ticks * 100 /
130                 iteration).ToString("N0") + "ns");
131 
132             // 5. Print GC
133             for (int i = 0; i <= GC.MaxGeneration; i++)
134             {
135                 int count = GC.CollectionCount(i) - gcCounts[i];
136                 Console.WriteLine("\tGen " + i + ": \t\t\t" + count);
137             }
138             Console.WriteLine();
139         }
140     }

有了上面的codeTimer我們就來測試一個吧，如字條串和并的問題，用+=還是用StringBuilder呢，有點經驗的程序員肯定說是StringBuilder，是的，確實是后者，那我們就來看看這

兩種方法測試的結果吧

 1      CodeTimer.Time("String  Concat", 100000,2                  () =>3                  {4                      var s = "1";5                      for (int i = 1; i < 10; i++)6                          s = s + "1";7                  });8 9       CodeTimer.Time("StringBuilder Concat", 100000,
10                () =>
11                {
12                    var s = new StringBuilder();
13                    for (int i = 1; i < 10; i++)
14                        s.Append("1");
15                });

測試的結果如下：

從圖中我們可以看到StringBuilder快的很明顯，無論是執行時間，還是對CPU的消耗及GC回收都遠低于String的拼結，所以，才有以下結論：

在字符串拼結時，請使用StringBuilder吧！