Tag Archives: CSharp

最近项目中用了COM控件，同时也用了多线程，在等待线程退出的地方，使用了

AutoResetEvent[] tEevents;
//...
WaitHandle.WaitAll(tEevents);

程序运行到这里，就会报错：

不支持一个STA线程上针对多个句柄的WaitAll

当时事情很急，将其调整为

AutoResetEvent[] tEevents;
//...
foreach(var tEvent in tEevents)
{
    tEvent.WaitOne();
}

就将这个问题绕了过去。

后来，在Stackoverflow上面，查了STA和MTA的区别。COM线程模型称为Apartment模型，分为STA和MTA两种。
STA（Single Thread Apartment）：
STA是非线程安全的，常用于UI界面，其他线程要访问STA模式的COM组件，需要通过STA线程进行访问（其实就变成了单线程调用）
MTA（Multi Thread Apartment）：
MTA是线程安全的，COM的程序员自己处理了并发的问题，其他线程可以直接访问COM组件

参考资料：
Could you explain STA and MTA?

        //Form程序
        private static String getExeFileFolder()
        {
            String strExeFolder = System.Reflection.Assembly.GetExecutingAssembly().Location;
            int nPos = strExeFolder.LastIndexOf("\\");
            if (nPos >= 0)
            {
                strExeFolder = strExeFolder.Substring(0, nPos + 1);
            }
            else
            {
                strExeFolder = strExeFolder + "\\";
            }

            return strExeFolder;
        }

        //IIS程序
        String rootPath = Request.PhysicalApplicationPath;
        String strExeFolder = getExeFileFolder(rootPath);
        private static String getExeFileFolder(String strExeFolder)
        {
            int nPos = strExeFolder.LastIndexOf("\\");
            if (nPos >= 0)
            {
                strExeFolder = strExeFolder.Substring(0, nPos + 1);
            }
            else
            {
                strExeFolder = strExeFolder + "\\";
            }

            return strExeFolder;
        }

        int nMaxThreadNum = 5;
        List<List<JobParam>> jobQueue = new List<List<JobParam>>();
        //...
        for (int i = 0; i < nMaxThreadNum;i++)
        {
            ThreadPool.QueueUserWorkItem(new WaitCallback(AsyncDoRetrieve), jobQueue&#91;i&#93;);
        }

        static void AsyncDoRetrieve(object state)
        {
            if (!(state == null && state is List<JobParam>)) return;
            List<JobParam> jobParams= state as List<JobParam> ;
            foreach(JobParam param in jobParams)
            {
                param.delegateDoSomeThing.BeginInvoke(param,null,null);
            }
        }

1.IDBHelper.cs

    interface IDBHelper
    {
        void initDB();
        void closeDB();
        void ExecSQL(String execSql);
        DataTable ExecQuery(String querySql);
    }

2.ZDBHelperSQLLite.cs

    class ZDBHelperSQLLite : IDBHelper
    {
        String dataSource = "";
        SQLiteConnection connection = null;
        public void initDB(String dbPath)
        {
            dataSource = "Data Source =" + dbPath();
            connection = new SQLiteConnection(dbFile);
            connection.Open();
            initTables();
            CreateFileInfoTable();
        }
        
        public void closeDB()
        {
            connection.Close();
        }

        private void initTables()
        {
            String sqlCreate01 = "CREATE TABLE IF NOT EXISTS visitlog(user_id varchar(64), visit_path varchar(256), visit_time integer);";
            SQLiteCommand cmdCreateTable = new SQLiteCommand(connection);
            cmdCreateTable.CommandText = sqlCreate01;
            cmdCreateTable.ExecuteNonQuery();
        }
  
        public void ExecSQL(String execSql)
        {
            SQLiteTransaction transaction = connection.BeginTransaction();
            SQLiteCommand cmdExec = new SQLiteCommand(execSql, connection, transaction );
            cmdExec.ExecuteNonQuery();
            transaction.Commit();
        }

        public DataTable ExecQuery(String querySql)
        {
            SQLiteCommand cmdQuery = new SQLiteCommand(querySql, connection);
            SQLiteDataReader reader = cmdQuery.ExecuteReader();

            DataTable datatable = new DataTable();
            DataTable schemaTable = reader.GetSchemaTable();
            foreach (DataRow myRow in schemaTable.Rows)
            {
                DataColumn myDataColumn = new DataColumn();
                myDataColumn.DataType = myRow.GetType();
                myDataColumn.ColumnName = myRow[0].ToString();
                datatable.Columns.Add(myDataColumn);
            }
            schemaTable = null;

            while (reader.Read())
            {
                DataRow myDataRow = datatable.NewRow();
                for (int i = 0; i < reader.FieldCount; i++)
                {
                    myDataRow[i] = reader[i].ToString();
                }
                datatable.Rows.Add(myDataRow);
                myDataRow = null;
            }
            reader.Close();

            return datatable;
        }
    }

1、新建一个Windows Service项目，重命名服务类名

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.ServiceProcess;
using System.Threading;

namespace ServiceTestCS
{
    public partial class ServiceTestCS : ServiceBase
    {
        //安装卸载时，最好用绝对路径哦
        //Installutil NASTestCS
        //Installutil -u NASTestCS

        private const int waitInterval = 200;
        private AutoResetEvent stopEvent = new AutoResetEvent(false);
        private AutoResetEvent pauseContinueEvent = new AutoResetEvent(false);
        private Thread workingThread = null;

        public NASTestCS()
        {
            InitializeComponent();
            this.CanPauseAndContinue = true;
            this.CanShutdown = true;
        }

        protected override void OnStart(string[] args)
        {
            #if DEBUG
            /*
            //等待调试器，但调试Windows服务时，提示没有加载符号
            while (!Debugger.IsAttached)
            {
                Thread.Sleep(waitInterval);
            }
            */
            Debugger.Launch();
            #endif

            workingThread = new Thread(new ThreadStart(MaiLoop));
            workingThread.Start();
        }

        protected override void OnStop()
        {
            stopEvent.Set();
        }

        protected override void OnShutdown()
        {
            stopEvent.Set();
        }

        protected override void OnPause()
        {
            pauseContinueEvent.Set();
        }

        protected override void OnContinue()
        {
            pauseContinueEvent.Set();
        }

        protected void MaiLoop()
        {
            Boolean bEnd = false;
            while (!bEnd)
            {
                //处理你的正常事务
                //但要保证下面的代码，可以定期被调用到
                //......

                //截获停止事件
                if(stopEvent.WaitOne(waitInterval))
                {
                    bEnd = true;
                    break;
                }

                //截获暂停事件
                if (pauseContinueEvent.WaitOne(waitInterval))
                {
                    //等待继续时间
                    while (!pauseContinueEvent.WaitOne(waitInterval))
                    {
                        //少占用一些资源
                        Thread.Sleep(waitInterval);

                        //暂停时也可以退出
                        if (stopEvent.WaitOne(waitInterval))
                        {
                            bEnd = true;
                            break;
                        }
                    }
                }
            }
        }
    }
}

2、服务设计界面右击，添加Service Installer
配置Service Installer，配置服务类名称，显示名称，启动类型，登录用户，服务依赖等
但如果要可以与桌面交互的话，需要添加代码实现。
双击serviceInstaller，添加下面方法：

        using System.Management;

        private void serviceInstaller_AfterInstall(object sender, InstallEventArgs e)
        {
            //要用LocalSystem用户登录才有效哦
            ManagementObject wmiService = new ManagementObject(string.Format("Win32_Service.Name='{0}'", this.serviceInstaller.ServiceName));
            ManagementBaseObject changeMethod = wmiService.GetMethodParameters("Change");
            changeMethod["DesktopInteract"] = true;
            ManagementBaseObject OutParam = wmiService.InvokeMethod("Change", changeMethod, null);
        }

3、安装与反安装，用命令行实现

rem 安装服务
%PATH_TO_INSTALLUTIL%\installutil.exe %PATH_TO_SERVICE%\NASTestCS.exe
rem 卸载服务
%PATH_TO_INSTALLUTIL%\installutil.exe -u %PATH_TO_SERVICE%\NASTestCS.exe