Asynchronious call Delegate

参见 http://blogs.yodersolutions.com/net/?p=17
当我们声明了Delegate 变量(比如FooDelegate), 我们可以使用下面两种方法,来触发这个Delegate,
1. FooDelegate.Invoke(), 或者直接是FooDelegate().
2. FooDelegate.BeginInvoke().
第一种调用方法是同步执行这个delegate.
而第二种方式是异步执行这个delegate, 这个delegate会在另一个线程中被执行, 当前线程将继续执行其它代码. 需要说明的是, 一定要确保这个delegate有机会调用了EndInvoke(), 否则会有资源和内存泄漏.
异步调用的一个简单示例是:
subscriber.BeginInvoke(this, new EventArgs(), Callback, subscriber);
其中第3个参数是回调函数, 它的签名是AsynCallback delegate.当subscriber被执行完后, Callback会被调用.
其中第4个参数一定要是subscriber本身,或者是subscriber本身的一个wrapper, 这样在callback函数体中, 就能访问到subscriber本身来EndInvoke.

    class Program
    {
        static void Main(string[] args)
        {
            EventPublisher eventPublisher = new EventPublisher();
            eventPublisher.FooEvent += new EventHandler(eventPublisher_FooEvent1);
            eventPublisher.FooEvent += new EventHandler(eventPublisher_FooEvent2);
            Stopwatch sw = new Stopwatch();
            sw.Start();
            eventPublisher.AsynFireFooEvent();
            Console.WriteLine(sw.ElapsedMilliseconds.ToString());
            Console.ReadKey();
        }

        static void eventPublisher_FooEvent1(object sender, EventArgs e)
        {
            Thread.Sleep(100);
        }
        static void eventPublisher_FooEvent2(object sender, EventArgs e)
        {
            Thread.Sleep(200);
        }
    }


    
    class EventPublisher
    {
        public event EventHandler FooEvent; 


        /// <summary>
        /// synchronized invoke the all the subscriber services. 
        /// The process will return until all delegates executions are over.
        /// </summary>
        public void FireFooEvent()
        {
            if (FooEvent != null)
                FooEvent(this, new EventArgs());
        }


        /// <summary> 
        /// Raising events asynchronously lets the event subscribers do their processing in another thread 
        /// and allows the thread that raised the event to continue processing.
        /// </summary>
        public void AsynFireFooEvent()
        {
            if (FooEvent != null)
            {
                Delegate[] subscribers =  FooEvent.GetInvocationList();
                foreach (EventHandler subscriber in subscribers)
                {
                    //the 3rd arg should be a AsyncCallback type delegate. When one subscriber service will completed, the AsyncCallback method will be raised. 

                    //the 4th arg should be the exact subscriber or subscriber wrapper, so that in callback function, 
                    // we can access the subcriber to call EndInvoke()
                    subscriber.BeginInvoke(this, new EventArgs(), Callback, subscriber);
                }
            }
        }



        void Callback(IAsyncResult ar)
        {
            EventHandler raisedEvent = (EventHandler)ar.AsyncState;
            raisedEvent.EndInvoke(ar);
        }
    }

Auto build script by using NAnt

当我们想专门为一个C#项目架一个build服务器, 怎样对VS的solution文件进行自动build是个问题, 最简单的办法是, 编写一个bat文件, 运行这个bat文件就能完成solution的编译甚至运行单元测试 . NAnt是个很好的选择.
简单地讲, NAnt就是一个能将xml文件作为参数的命令行工具, 你可以在这个xml中按照NAnt的schema编写你想要完成的任务, 比如压缩文件, 比如删除目录, 当然NAnt最主要的作用是可以编写任务来批量编译c#的代码. 但是考虑到MS官方已经发布了msbuild, 所以一个比较好的做法是：在NAnt的参数xml文件中, 使用msbuild来编译.Net solution, 用NAnt本身的功能完成其它事情.
当然对于Nant新手来说, 编写这样的xml并不简单. 幸好我们有一些现成工具可以使用, Tree Surgeon就是这样一个开源项目(http://www.codeplex.com/treesurgeon).
TreeSurgeon不仅仅帮你编写xml的build文件(你可以根据需要做比较的修改), 而且会自动将NAnt以及NUnit等整理到一个tools目录. Treesurgeon创建的solution目录结构也很有参考价值, 比如和src目录同级别的目录, 还有bin, tools, lib, dist目录, 其中bin是存放solution的输出文件(需要在Visual studio中将这个solution的所有project的output目录制定到这个bin目录), dist目录是专门作为solution的release目录.
如果想测试这个xml文件中某些变量设置是否正确, 可以使用在project tag之下, 创建echo tag, 在用NAnt执行这个xml文件时, echo中的message信息就会被输出到屏幕上.

<echo message="${framework::get-framework-directory(framework::get-target-framework())}\msbuild.exe"/>

下面的bat和xml是使用NAnt的示例(它是由TreeSurgeon生成, 并参考了Ninject源码中的NAnt build_xml文件). 使用非常方便,
cmd> build 或
cmd> build test
build.bat的内容是:

@tools\nant\NAnt.exe -buildfile:DbGear.build %*
rem pause

DbGear.build是一个xml文件, 用NAnt命令行程序执行这个xml文件(NAnt0.86版本如用msbuild tag来调用.net 3.5 的msbuild时候, 会有bug. 所以这个例子并没有使用常规的msbuild tag,而是使用 exec tag直接调用3.5版本的msbuild命令行程序)

<?xml version="1.0" ?>
<!--refer to treesurgeon on codeplex, and build file of ninject project-->
<project name="DbGear" default="compile" xmlns="http://nant.sf.net/schemas/nant.xsd">
    <!--tell NAnt try to use msbuild from .net sdk 3.5-->    
    <property name="nant.settings.currentframework" value="net-3.5" />

    <!--declare path variables-->
    <property name="path.base" value="${project::get-base-directory()}"/>
    <property name="path.src" value="${path.base}/src"/>
    <property name="path.tools" value="${path.base}/tools"/>
    <property name="path.build" value="${path.base}/bin"/>
    <property name="path.dist" value="${path.base}/dist"/>
    <property name="path.build.testresult" value="${path.build}/test-result"/>
    <property name="path.build.debug" value="${path.build}/debug"/>

    <!--define solution variables-->
    <property name="version" value="1.0.0.0" overwrite="false"/>
    <property name="file.solution" value="${path.src}/DbGear.sln"/>
    <!--choose one suitable compiling config, eg Debug, Release or other customized config schema-->
    <property name="build.configuration" value="debug"/>

    <!-- define build  targets -->
    <target name="clean" description="Delete Automated Build artifacts">
        <delete dir="${path.build}" if="${directory::exists(path.build)}"/>
        <delete dir="${path.dist}" if="${directory::exists(path.dist)}"/>
    </target>

    <target name="init" description="create assembly out path">
        <mkdir dir="${path.dist}" if="${not(directory::exists(path.dist))}"/>
        <mkdir dir="${path.build}" if="${not(directory::exists(path.build))}"/>
        <mkdir dir="${path.build.testresult}" if="${not(directory::exists(path.build.testresult))}"/>
        <mkdir dir="${path.build.debug}" if="${not(directory::exists(path.build.debug))}"/>
    </target>
    
    
    
    <echo message="Build configuration:" />
    <echo message="${framework::get-framework-directory(framework::get-target-framework())}\msbuild.exe"/>

    <!--nant0.86 has a bug  with  Framework 3.5 section,  so we will use exec to call msbuild.exe of 3.5, rather than the regular msbuild  tag -->
    <!--
    <target name="compile" depends="init"  description="Compiles using the AutomatedDebug Configuration">
        <msbuild project="${file.solution}">
            <property name="Configuration" value="${build.configuration}" />
        </msbuild>
    </target>
         -->
      
     <target name="compile" depends="init" description="Compiles using the Debug Configuration">
        <exec program="${framework::get-framework-directory(framework::get-target-framework())}\msbuild.exe" > 
        <arg value="${file.solution}" />   
        <arg value="/verbosity:minimal" />
        <arg value="/property:Configuration=${build.configuration}" />
        <arg value="/property:WarningLevel=0" /> 
        </exec>
     </target>
    
    <target name="test" depends="compile, unittest"
        description="Compile and Run Tests" />

    <target name="full" depends="clean, test"
        description="Compiles, tests, and produces distributions" />

    <!-- Internal targets -->
    <target name="unittest" description="runs the unit tests">
        <!-- Test Assembly -->
        <exec program="${path.tools}/nunit/nunit-console.exe">
            <arg value="${path.build.debug}/UnitTests.dll" />
            <arg value="/xml=${path.build.testresult}/UnitTests-Results.xml" />
        </exec>
    </target>


    <target name="dist">
        <zip zipfile="${path.dist}\DbGear-${version}.zip">
            <fileset basedir="${path.build.debug}">
                <include name="**/*" />
                <exclude name="**/*.pdb" />
            </fileset>
        </zip>
    </target>


    <target name="package-source">
        <zip zipfile="${path.dist}\DbGear-${version}-source.zip" ziplevel="9">
            <fileset basedir="${path.src}">
                <include name="**/*.cs"/>
                <include name="**/*.csproj"/>
                <include name="**/*.sln"/>
                <include name="**/*.txt"/>
                <include name="**/*.build"/>
                <exclude name="**/*.pdb" />
            </fileset>
        </zip>
    </target>
</project>