编译器处理while，for结构的小发现

在做一个日报自动报表发送项目时，因为项目是Windows服务，而且报表是每天自动发送，所以里面有这么一个函数

 

        public void AutoReportSend()
        {
            while (true)
            {

                try
                {
                    //采集时间没到，则结束。直到采集时间才开始采集作业
                    if (DateTime.Now < SystemConfiguration.GetInstance().GatherTime)
                    {
                        Thread.Sleep((TimeSpan)(SystemConfiguration.GetInstance().GatherTime - DateTime.Now));
                    }

                    log.Info("邮件发送开始！");

                    ReportDataProcess model = new ReportDataProcess();
                    model.GenerateReport();


                    EmailUtil emailUtil = new EmailUtil();
                 
                    string filePath = ConfigurationSettings.AppSettings["filePath"].ToString();
                    string fileName = ConfigurationSettings.AppSettings["fileName"].ToString();



                    emailUtil.IsBodyHtml = true;

                    emailUtil.EmailTitle = DateTime.Now.ToString("yyyy") + "年" + DateTime.Now.Month.ToString() + "月"
                        + DateTime.Now.Day.ToString() + "日" + ConfigurationSettings.AppSettings["EmailTitle"].ToString();
                    emailUtil.EmSubject = ConfigurationSettings.AppSettings["EmSubject"].ToString();
                    emailUtil.SendEmilPerson = ConfigurationSettings.AppSettings["SendEmil"].ToString();

                    emailUtil.ToEmail = ConfigurationSettings.AppSettings["ToEmail"].ToString();
                    emailUtil.FromEmail = ConfigurationSettings.AppSettings["SendEmil"].ToString();

                    emailUtil.SendEmailAcount = ConfigurationSettings.AppSettings["SendEmailAcount"].ToString();
                    emailUtil.SendEmailPsd = ConfigurationSettings.AppSettings["SendEmialPswd"].ToString();

                    emailUtil.SetEmailAttactment(fileName, filePath);


                    emailUtil.SmtpHost = ConfigurationSettings.AppSettings["SmtpHost"].ToString();
                    emailUtil.SmtpServePort = ConfigurationSettings.AppSettings["SmtpServePort"].ToString();

                    emailUtil.EmailContent = ConfigurationSettings.AppSettings["EmailContent"].ToString();




                    emailUtil.SendEmail();


                    log.Info("邮件发送成功！");

                    DateTime dtNow = DateTime.Now;

                    DateTime dtNext = Convert.ToDateTime(DateTime.Now.ToString("yyyy-MM-dd") + " " + SystemConfiguration.GetInstance().GatherHour + ":" + SystemConfiguration.GetInstance().GatherMinute);


                    Thread.Sleep((TimeSpan)(dtNext.AddDays(1) - dtNow));

                }
                catch (Exception exc)
                {
                    log.Error(exc.ToString());
                    //发送报错短信
                    SendMessage.MessageSending("函数AutoReportSend 出错，具体情况请检查日志");

                    Thread.Sleep(600000);
                }
            }
        }

 

 

 

偶然情况下让我发现了一个让我觉得比较有趣的问题：我用.NET Reflector工具查看项目的exe文件时候，发现里面的这段代码变成了下面的样子

 

publicvoid AutoReportSend()
{
Label_0000:
    try
    {
        if (DateTime.Now < SystemConfiguration.GetInstance().GatherTime)
        {
            Thread.Sleep((TimeSpan) (SystemConfiguration.GetInstance().GatherTime - DateTime.Now));
        }
        log.Info("邮件发送开始！");
        new ReportDataProcess().GenerateReport();
        EmailUtil emailUtil =new EmailUtil();
        string filePath = ConfigurationSettings.AppSettings["filePath"].ToString();
        string fileName = ConfigurationSettings.AppSettings["fileName"].ToString();
        emailUtil.set_IsBodyHtml(true);
        emailUtil.set_EmailTitle(DateTime.Now.ToString("yyyy") +"年"+ DateTime.Now.Month.ToString() +"月"+ DateTime.Now.Day.ToString() +"日"+ ConfigurationSettings.AppSettings["EmailTitle"].ToString());
        emailUtil.set_EmSubject(ConfigurationSettings.AppSettings["EmSubject"].ToString());
        emailUtil.set_SendEmilPerson(ConfigurationSettings.AppSettings["SendEmil"].ToString());
        emailUtil.set_ToEmail(ConfigurationSettings.AppSettings["ToEmail"].ToString());
        emailUtil.set_FromEmail(ConfigurationSettings.AppSettings["SendEmil"].ToString());
        emailUtil.set_SendEmailAcount(ConfigurationSettings.AppSettings["SendEmailAcount"].ToString());
        emailUtil.set_SendEmailPsd(ConfigurationSettings.AppSettings["SendEmialPswd"].ToString());
        emailUtil.SetEmailAttactment(fileName, filePath);
        emailUtil.set_SmtpHost(ConfigurationSettings.AppSettings["SmtpHost"].ToString());
        emailUtil.set_SmtpServePort(ConfigurationSettings.AppSettings["SmtpServePort"].ToString());
        emailUtil.set_EmailContent(ConfigurationSettings.AppSettings["EmailContent"].ToString());
        emailUtil.SendEmail();
        log.Info("邮件发送成功！");
        DateTime dtNow = DateTime.Now;
        Thread.Sleep((TimeSpan) (Convert.ToDateTime(DateTime.Now.ToString("yyyy-MM-dd") +""+ SystemConfiguration.GetInstance().GatherHour +":"+ SystemConfiguration.GetInstance().GatherMinute).AddDays(1.0) - dtNow));
        goto Label_0000;
    }
    catch (Exception exc)
    {
        log.Error(exc.ToString());
        SendMessage.MessageSending("函数AutoReportSend 出错，具体情况请检查日志");
        Thread.Sleep(0x927c0);
        goto Label_0000;
    }
}

 

反编译的IL代码如下：

 

.method public hidebysig instance void AutoReportSend() cil managed
  2 {
  3     .maxstack 5
  4     .locals init (
  5         [0] class [GSP.Bll.ThreeCountry]GSP.Bll.ThreeCountry.ReportDataProcess model,
  6         [1] class [GSP.Common]GSP.Common.Utils.EmailUtil emailUtil,
  7         [2] string filePath,
  8         [3] string fileName,
  9         [4] valuetype [mscorlib]System.DateTime dtNow,
 10         [5] valuetype [mscorlib]System.DateTime dtNext,
 11         [6] class [mscorlib]System.Exception exc,
 12         [7] string[] CS$0$0000,
 13         [8] valuetype [mscorlib]System.DateTime CS$0$0001,
 14         [9] valuetype [mscorlib]System.DateTime CS$0$0002,
 15         [10] int32 CS$0$0003,
 16         [11] valuetype [mscorlib]System.DateTime CS$0$0004,
 17         [12] int32 CS$0$0005,
 18         [13] string[] CS$0$0006,
 19         [14] valuetype [mscorlib]System.DateTime CS$0$0007)
 20     L_0000: call valuetype [mscorlib]System.DateTime [mscorlib]System.DateTime::get_Now()
 21     L_0005: call class ExcelAutoReport.SystemConfiguration ExcelAutoReport.SystemConfiguration::GetInstance()
 22     L_000a: callvirt instance valuetype [mscorlib]System.DateTime ExcelAutoReport.SystemConfiguration::get_GatherTime()
 23     L_000f: call bool [mscorlib]System.DateTime::op_LessThan(valuetype [mscorlib]System.DateTime, valuetype [mscorlib]System.DateTime)
 24     L_0014: brfalse.s L_002f
 25     L_0016: call class ExcelAutoReport.SystemConfiguration ExcelAutoReport.SystemConfiguration::GetInstance()
 26     L_001b: callvirt instance valuetype [mscorlib]System.DateTime ExcelAutoReport.SystemConfiguration::get_GatherTime()
 27     L_0020: call valuetype [mscorlib]System.DateTime [mscorlib]System.DateTime::get_Now()
 28     L_0025: call valuetype [mscorlib]System.TimeSpan [mscorlib]System.DateTime::op_Subtraction(valuetype [mscorlib]System.DateTime, valuetype [mscorlib]System.DateTime)
 29     L_002a: call void [mscorlib]System.Threading.Thread::Sleep(valuetype [mscorlib]System.TimeSpan)
 30     L_002f: ldsfld class [log4net]log4net.ILog ExcelAutoReport.SftxExcelAutoReport::log
 31     L_0034: ldstr "\u90ae\u4ef6\u53d1\u9001\u5f00\u59cb\uff01"
 32     L_0039: callvirt instance void [log4net]log4net.ILog::Info(object)
 33     L_003e: newobj instance void [GSP.Bll.ThreeCountry]GSP.Bll.ThreeCountry.ReportDataProcess::.ctor()
 34     L_0043: stloc.0 
 35     L_0044: ldloc.0 
 36     L_0045: callvirt instance void [GSP.Bll.ThreeCountry]GSP.Bll.ThreeCountry.ReportDataProcess::GenerateReport()
 37     L_004a: newobj instance void [GSP.Common]GSP.Common.Utils.EmailUtil::.ctor()
 38     L_004f: stloc.1 
 39     L_0050: call class [System]System.Collections.Specialized.NameValueCollection [System]System.Configuration.ConfigurationSettings::get_AppSettings()
 40     L_0055: ldstr "filePath"
 41     L_005a: callvirt instance string [System]System.Collections.Specialized.NameValueCollection::get_Item(string)
 42     L_005f: callvirt instance string [mscorlib]System.Object::ToString()
 43     L_0064: stloc.2 
 44     L_0065: call class [System]System.Collections.Specialized.NameValueCollection [System]System.Configuration.ConfigurationSettings::get_AppSettings()
 45     L_006a: ldstr "fileName"
 46     L_006f: callvirt instance string [System]System.Collections.Specialized.NameValueCollection::get_Item(string)
 47     L_0074: callvirt instance string [mscorlib]System.Object::ToString()
 48     L_0079: stloc.3 
 49     L_007a: ldloc.1 
 50     L_007b: ldc.i4.1 
 51     L_007c: callvirt instance void [GSP.Common]GSP.Common.Utils.EmailUtil::set_IsBodyHtml(bool)
 52     L_0081: ldloc.1 
 53     L_0082: ldc.i4.7 
 54     L_0083: newarr string
 55     L_0088: stloc.s CS$0$0000
 56     L_008a: ldloc.s CS$0$0000
 57     L_008c: ldc.i4.0 
 58     L_008d: call valuetype [mscorlib]System.DateTime [mscorlib]System.DateTime::get_Now()
 59     L_0092: stloc.s CS$0$0001
 60     L_0094: ldloca.s CS$0$0001
 61     L_0096: ldstr "yyyy"
 62     L_009b: call instance string [mscorlib]System.DateTime::ToString(string)
 63     L_00a0: stelem.ref 
 64     L_00a1: ldloc.s CS$0$0000
 65     L_00a3: ldc.i4.1 
 66     L_00a4: ldstr "\u5e74"
 67     L_00a9: stelem.ref 
 68     L_00aa: ldloc.s CS$0$0000
 69     L_00ac: ldc.i4.2 
 70     L_00ad: call valuetype [mscorlib]System.DateTime [mscorlib]System.DateTime::get_Now()
 71     L_00b2: stloc.s CS$0$0002
 72     L_00b4: ldloca.s CS$0$0002
 73     L_00b6: call instance int32 [mscorlib]System.DateTime::get_Month()
 74     L_00bb: stloc.s CS$0$0003
 75     L_00bd: ldloca.s CS$0$0003
 76     L_00bf: call instance string [mscorlib]System.Int32::ToString()
 77     L_00c4: stelem.ref 
 78     L_00c5: ldloc.s CS$0$0000
 79     L_00c7: ldc.i4.3 
 80     L_00c8: ldstr "\u6708"
 81     L_00cd: stelem.ref 
 82     L_00ce: ldloc.s CS$0$0000
 83     L_00d0: ldc.i4.4 
 84     L_00d1: call valuetype [mscorlib]System.DateTime [mscorlib]System.DateTime::get_Now()
 85     L_00d6: stloc.s CS$0$0004
 86     L_00d8: ldloca.s CS$0$0004
 87     L_00da: call instance int32 [mscorlib]System.DateTime::get_Day()
 88     L_00df: stloc.s CS$0$0005
 89     L_00e1: ldloca.s CS$0$0005
 90     L_00e3: call instance string [mscorlib]System.Int32::ToString()
 91     L_00e8: stelem.ref 
 92     L_00e9: ldloc.s CS$0$0000
 93     L_00eb: ldc.i4.5 
 94     L_00ec: ldstr "\u65e5"
 95     L_00f1: stelem.ref 
 96     L_00f2: ldloc.s CS$0$0000
 97     L_00f4: ldc.i4.6 
 98     L_00f5: call class [System]System.Collections.Specialized.NameValueCollection [System]System.Configuration.ConfigurationSettings::get_AppSettings()
 99     L_00fa: ldstr "EmailTitle"
100     L_00ff: callvirt instance string [System]System.Collections.Specialized.NameValueCollection::get_Item(string)
101     L_0104: callvirt instance string [mscorlib]System.Object::ToString()
102     L_0109: stelem.ref 
103     L_010a: ldloc.s CS$0$0000
104     L_010c: call string [mscorlib]System.String::Concat(string[])
105     L_0111: callvirt instance void [GSP.Common]GSP.Common.Utils.EmailUtil::set_EmailTitle(string)
106     L_0116: ldloc.1 
107     L_0117: call class [System]System.Collections.Specialized.NameValueCollection [System]System.Configuration.ConfigurationSettings::get_AppSettings()
108     L_011c: ldstr "EmSubject"
109     L_0121: callvirt instance string [System]System.Collections.Specialized.NameValueCollection::get_Item(string)
110     L_0126: callvirt instance string [mscorlib]System.Object::ToString()
111     L_012b: callvirt instance void [GSP.Common]GSP.Common.Utils.EmailUtil::set_EmSubject(string)
112     L_0130: ldloc.1 
113     L_0131: call class [System]System.Collections.Specialized.NameValueCollection [System]System.Configuration.ConfigurationSettings::get_AppSettings()
114     L_0136: ldstr "SendEmil"
115     L_013b: callvirt instance string [System]System.Collections.Specialized.NameValueCollection::get_Item(string)
116     L_0140: callvirt instance string [mscorlib]System.Object::ToString()
117     L_0145: callvirt instance void [GSP.Common]GSP.Common.Utils.EmailUtil::set_SendEmilPerson(string)
118     L_014a: ldloc.1 
119     L_014b: call class [System]System.Collections.Specialized.NameValueCollection [System]System.Configuration.ConfigurationSettings::get_AppSettings()
120     L_0150: ldstr "ToEmail"
121     L_0155: callvirt instance string [System]System.Collections.Specialized.NameValueCollection::get_Item(string)
122     L_015a: callvirt instance string [mscorlib]System.Object::ToString()
123     L_015f: callvirt instance void [GSP.Common]GSP.Common.Utils.EmailUtil::set_ToEmail(string)
124     L_0164: ldloc.1 
125     L_0165: call class [System]System.Collections.Specialized.NameValueCollection [System]System.Configuration.ConfigurationSettings::get_AppSettings()
126     L_016a: ldstr "SendEmil"
127     L_016f: callvirt instance string [System]System.Collections.Specialized.NameValueCollection::get_Item(string)
128     L_0174: callvirt instance string [mscorlib]System.Object::ToString()
129     L_0179: callvirt instance void [GSP.Common]GSP.Common.Utils.EmailUtil::set_FromEmail(string)
130     L_017e: ldloc.1 
131     L_017f: call class [System]System.Collections.Specialized.NameValueCollection [System]System.Configuration.ConfigurationSettings::get_AppSettings()
132     L_0184: ldstr "SendEmailAcount"
133     L_0189: callvirt instance string [System]System.Collections.Specialized.NameValueCollection::get_Item(string)
134     L_018e: callvirt instance string [mscorlib]System.Object::ToString()
135     L_0193: callvirt instance void [GSP.Common]GSP.Common.Utils.EmailUtil::set_SendEmailAcount(string)
136     L_0198: ldloc.1 
137     L_0199: call class [System]System.Collections.Specialized.NameValueCollection [System]System.Configuration.ConfigurationSettings::get_AppSettings()
138     L_019e: ldstr "SendEmialPswd"
139     L_01a3: callvirt instance string [System]System.Collections.Specialized.NameValueCollection::get_Item(string)
140     L_01a8: callvirt instance string [mscorlib]System.Object::ToString()
141     L_01ad: callvirt instance void [GSP.Common]GSP.Common.Utils.EmailUtil::set_SendEmailPsd(string)
142     L_01b2: ldloc.1 
143     L_01b3: ldloc.3 
144     L_01b4: ldloc.2 
145     L_01b5: callvirt instance void [GSP.Common]GSP.Common.Utils.EmailUtil::SetEmailAttactment(string, string)
146     L_01ba: ldloc.1 
147     L_01bb: call class [System]System.Collections.Specialized.NameValueCollection [System]System.Configuration.ConfigurationSettings::get_AppSettings()
148     L_01c0: ldstr "SmtpHost"
149     L_01c5: callvirt instance string [System]System.Collections.Specialized.NameValueCollection::get_Item(string)
150     L_01ca: callvirt instance string [mscorlib]System.Object::ToString()
151     L_01cf: callvirt instance void [GSP.Common]GSP.Common.Utils.EmailUtil::set_SmtpHost(string)
152     L_01d4: ldloc.1 
153     L_01d5: call class [System]System.Collections.Specialized.NameValueCollection [System]System.Configuration.ConfigurationSettings::get_AppSettings()
154     L_01da: ldstr "SmtpServePort"
155     L_01df: callvirt instance string [System]System.Collections.Specialized.NameValueCollection::get_Item(string)
156     L_01e4: callvirt instance string [mscorlib]System.Object::ToString()
157     L_01e9: callvirt instance void [GSP.Common]GSP.Common.Utils.EmailUtil::set_SmtpServePort(string)
158     L_01ee: ldloc.1 
159     L_01ef: call class [System]System.Collections.Specialized.NameValueCollection [System]System.Configuration.ConfigurationSettings::get_AppSettings()
160     L_01f4: ldstr "EmailContent"
161     L_01f9: callvirt instance string [System]System.Collections.Specialized.NameValueCollection::get_Item(string)
162     L_01fe: callvirt instance string [mscorlib]System.Object::ToString()
163     L_0203: callvirt instance void [GSP.Common]GSP.Common.Utils.EmailUtil::set_EmailContent(string)
164     L_0208: ldloc.1 
165     L_0209: callvirt instance void [GSP.Common]GSP.Common.Utils.EmailUtil::SendEmail()
166     L_020e: ldsfld class [log4net]log4net.ILog ExcelAutoReport.SftxExcelAutoReport::log
167     L_0213: ldstr "\u90ae\u4ef6\u53d1\u9001\u6210\u529f\uff01"
168     L_0218: callvirt instance void [log4net]log4net.ILog::Info(object)
169     L_021d: call valuetype [mscorlib]System.DateTime [mscorlib]System.DateTime::get_Now()
170     L_0222: stloc.s dtNow
171     L_0224: ldc.i4.5 
172     L_0225: newarr string
173     L_022a: stloc.s CS$0$0006
174     L_022c: ldloc.s CS$0$0006
175     L_022e: ldc.i4.0 
176     L_022f: call valuetype [mscorlib]System.DateTime [mscorlib]System.DateTime::get_Now()
177     L_0234: stloc.s CS$0$0007
178     L_0236: ldloca.s CS$0$0007
179     L_0238: ldstr "yyyy-MM-dd"
180     L_023d: call instance string [mscorlib]System.DateTime::ToString(string)
181     L_0242: stelem.ref 
182     L_0243: ldloc.s CS$0$0006
183     L_0245: ldc.i4.1 
184     L_0246: ldstr ""
185     L_024b: stelem.ref 
186     L_024c: ldloc.s CS$0$0006
187     L_024e: ldc.i4.2 
188     L_024f: call class ExcelAutoReport.SystemConfiguration ExcelAutoReport.SystemConfiguration::GetInstance()
189     L_0254: callvirt instance string ExcelAutoReport.SystemConfiguration::get_GatherHour()
190     L_0259: stelem.ref 
191     L_025a: ldloc.s CS$0$0006
192     L_025c: ldc.i4.3 
193     L_025d: ldstr ":"
194     L_0262: stelem.ref 
195     L_0263: ldloc.s CS$0$0006
196     L_0265: ldc.i4.4 
197     L_0266: call class ExcelAutoReport.SystemConfiguration ExcelAutoReport.SystemConfiguration::GetInstance()
198     L_026b: callvirt instance string ExcelAutoReport.SystemConfiguration::get_GatherMinute()
199     L_0270: stelem.ref 
200     L_0271: ldloc.s CS$0$0006
201     L_0273: call string [mscorlib]System.String::Concat(string[])
202     L_0278: call valuetype [mscorlib]System.DateTime [mscorlib]System.Convert::ToDateTime(string)
203     L_027d: stloc.s dtNext
204     L_027f: ldloca.s dtNext
205     L_0281: ldc.r8 1
206     L_028a: call instance valuetype [mscorlib]System.DateTime [mscorlib]System.DateTime::AddDays(float64)
207     L_028f: ldloc.s dtNow
208     L_0291: call valuetype [mscorlib]System.TimeSpan [mscorlib]System.DateTime::op_Subtraction(valuetype [mscorlib]System.DateTime, valuetype [mscorlib]System.DateTime)
209     L_0296: call void [mscorlib]System.Threading.Thread::Sleep(valuetype [mscorlib]System.TimeSpan)
210     L_029b: leave L_0000
211     L_02a0: stloc.s exc
212     L_02a2: ldsfld class [log4net]log4net.ILog ExcelAutoReport.SftxExcelAutoReport::log
213     L_02a7: ldloc.s exc
214     L_02a9: callvirt instance string [mscorlib]System.Object::ToString()
215     L_02ae: callvirt instance void [log4net]log4net.ILog::Error(object)
216     L_02b3: ldstr "\u51fd\u6570AutoReportSend \u51fa\u9519\uff0c\u5177\u4f53\u60c5\u51b5\u8bf7\u68c0\u67e5\u65e5\u5fd7"
217     L_02b8: call void [GSP.Common]GSP.Common.SendMessage::MessageSending(string)
218     L_02bd: ldc.i4 0x927c0
219     L_02c2: call void [mscorlib]System.Threading.Thread::Sleep(int32)
220     L_02c7: leave L_0000
221     .try L_0000 to L_02a0 catch [mscorlib]System.Exception handler L_02a0 to L_02cc
222 }
223 
224  
225 
226  
227  

 

 

看来编译的时候，编译器把while(true)转换成了goto结构，以前见过一片文章介绍goto结构在程序开发中的优劣，高德纳也曾为迪杰斯对goto语句的批评而辩护过，看来在开发过程中适当的、少量的使用goto结构也是有利于提高效率的，要不编译器也不会做这样的处理，接下来我试验了下，对for， while结构中对break，continue，编译器会做什么优化处理，下面是我发现的几种情况（只列举下for的代码例子）

 

    public int SummaryArray1(int[] array)
    {
            int result = 0;

            for (int index = 0; index < array.Length; index++)
            {
                if (index == 3) break;
                result += array[index];
            }

            return result;
    }
  
.NET Reflector 下查看到得代码如下：

   public int SummaryArray1(int[] array)
   {
   　　 int result = 0;
    　　for (int index = 0; index < array.Length; index++)
    　　{
       　　 if (index == 3)
        　　{
           　　 return result;
        　　}
       　　 result += array[index];
    　　 }
    　　return result;
　}

 

 

 

   public double SummarySalary1()
   {
            double[] number = { 1200, 1763.4, -15, 3700, 2589, 4366, 3335.8 };

            double summaryNum = 0;
            for (int index = 0; index < 7; index++)
            {
                if (number[index] < 0)
                    continue;

                summaryNum += number[index];
            }

            return summaryNum;
    }
.NET Reflector下查看到的代码如下：

   public double SummarySalary1()
   {
    　　double[] number = new double[] { 1200.0, 1763.4, -15.0, 3700.0, 2589.0, 4366.0, 3335.8 };
   　　 double summaryNum = 0.0;
    　　for (int index = 0; index < 7; index++)
   　　 {
        　　if (number[index] >= 0.0)
        　　{
            　　summaryNum += number[index];
        　　}
    　　}
    　　return summaryNum;
    }

 

 

 

如果编译器会做如此处理，我觉得是否可以在代码中也这样处理，替换continue，break呢，希望大家多多讨论，集思广益。