实现更简单的异步操作

前言

在.net4.0以后异步操作,并行计算变得异常简单,但是由于公司项目开发基于.net3.5所以无法用到4.0的并行计算以及Task等异步编程。因此,为了以后更方便的进行异步方式的开发,我封装实现了异步编程框架,通过BeginInvoke、EndInvoke的方式实现异步编程。

框架结构

整个框架包括四个部分

1. 基类抽象Opeartor
   异步操作的基类，实现了异步操作接口
2. FuncAsync
   异步的Func
3. ActionAsync
   异步的Action

4. Asynchorus
   对ActionAsync和FuncAsync的封装

   Operator

   Operator是一个抽象类,实现了IOperationAsync和IContinueWithAsync两个接口。
   IOperationAsync实现了异步操作,IContinueWithAsync实现了类似于Task的ContinueWith方法,在当前异步操作完成后继续进行的操作

   IOperationAsync接口详解

    public interface IOperationAsync
    {
        IAsyncResult Invoke();
        void Wait();
        void CompletedCallBack(IAsyncResult ar);
        void CatchException(Exception exception);
    }

• Invoke():异步方法的调用
• Wait():等待异步操作执行
• CompletedCallBack():操作完成回调
• CatchException():抓取异常

IContinueWithAsync接口详情

public interface IContinueWithAsync
{
    Operator Previous { get; set; }
    Operator Next { get; set; }
    Operator ContinueWithAsync(Action action);
    Operator ContinueWithAsync(Action action, TParameter parameter);
}

• Previous:前一个操作
• Next:下一个操作
• ContinueWithAsync():异步继续操作

public abstract class Operator : IOperationAsync, IContinueWithAsync
{
    public IAsyncResult Middle;
    public readonly string Id;
    public Exception Exception { get; private set; }
    public Operator Previous { get; set; }
    public Operator Next { get; set; }
    protected Operator()
    {
        Id = Guid.NewGuid().ToString();
    }
    public abstract IAsyncResult Invoke();
    protected void SetAsyncResult(IAsyncResult result)
    {
        this.Middle = result;
    }
    public virtual void Wait()
    {
        if (!Middle.IsCompleted) Middle.AsyncWaitHandle.WaitOne();
    }
    public virtual void CompletedCallBack(IAsyncResult ar)
    {
    }
    public void CatchException(Exception exception)
    {
        this.Exception = exception;
    }
    protected Operator ContinueAsync()
    {
        if (Next != null) Next.Invoke();
        return Next;
    }
    public virtual Operator ContinueWithAsync(Action action)
    {
        Next = new ActionAsync(action);
        Next.Previous = this;
        return Next;
    }
    public virtual Operator ContinueWithAsync(Action action, TParameter parameter)
    {
        Next = new ActionAsync(action, parameter);
        Next.Previous = this;
        return Next;
    }
    public virtual Operator ContinueWithAsync(Func func)
    {
        Next = new FuncAsync();
        Next.Previous = this;
        return Next;
    }
    public virtual Operator ContinueWithAsync(Func func,
        TParameter parameter)
    {
        Next = new FuncAsync(func, parameter);
        Next.Previous = this;
        return Next;
    }
}

无返回异步操作

ActionAsync

public class ActionAsync : Operator
{
    private readonly Action _action;
    protected ActionAsync()
    {
    }
    public ActionAsync(Action action)
        : this()
    {
        this._action = action;
    }
    public override IAsyncResult Invoke()
    {
        var middle = _action.BeginInvoke(CompletedCallBack, null);
        SetAsyncResult(middle);
        return middle;
    }
    public override void CompletedCallBack(IAsyncResult ar)
    {
        try
        {
            _action.EndInvoke(ar);
        }
        catch (Exception exception)
        {
            this.CatchException(exception);
        }
        ContinueAsync();
    }
}
public class ActionAsync : ActionAsync
{
    public T Result;
    private readonly Action _action1;
    protected readonly T Parameter1;
    public ActionAsync()
    {
    }
    public ActionAsync(T parameter)
    {
        this.Parameter1 = parameter;
    }
    public ActionAsync(Action action, T parameter)
    {
        this._action1 = action;
        this.Parameter1 = parameter;
    }
    public override IAsyncResult Invoke()
    {
        var result = _action1.BeginInvoke(Parameter1, CompletedCallBack, null);
        SetAsyncResult(result);
        return result;
    }
    public override void CompletedCallBack(IAsyncResult ar)
    {
        try
        {
            _action1.EndInvoke(ar);
        }
        catch (Exception exception)
        {
            this.CatchException(exception);
        }
        ContinueAsync();
    }
}

有返回异步

FuncAsync实现了IFuncOperationAsync 接口

IFuncOperationAsync

public interface IFuncOperationAsync
{
    void SetResult(T result);
    T GetResult();
}

• SetResult(T result):异步操作完成设置返回值

• GetResult():获取返回值

  FuncAsync

public class FuncAsync : Operator, IFuncOperationAsync
{
    private TResult _result;

    public TResult Result
    {
        get
        {
            if (!Middle.IsCompleted || _result == null)
            {
                _result = GetResult();
            }
            return _result;
        }
    }
    private readonly Func _func1;
    public FuncAsync()
    {
    }
    public FuncAsync(Func func)
    {
        this._func1 = func;
    }
    public override IAsyncResult Invoke()
    {
        var result = _func1.BeginInvoke(CompletedCallBack, null);
        SetAsyncResult(result);
        return result;
    }
    public override void CompletedCallBack(IAsyncResult ar)
    {
        try
        {
            var result = _func1.EndInvoke(ar);
            SetResult(result);
        }
        catch (Exception exception)
        {
            this.CatchException(exception);
            SetResult(default(TResult));
        }
        ContinueAsync();
    }
    public virtual TResult GetResult()
    {
        Wait();
        return this._result;
    }
    public void SetResult(TResult result)
    {
        _result = result;
    }
}
public class FuncAsync : FuncAsync
{
    protected readonly T1 Parameter1;
    private readonly Func _func2;
    public FuncAsync(Func action, T1 parameter1)
        : this(parameter1)
    {
        this._func2 = action;
    }
    protected FuncAsync(T1 parameter1)
        : base()
    {
        this.Parameter1 = parameter1;
    }
    public override IAsyncResult Invoke()
    {
        var result = _func2.BeginInvoke(Parameter1, CompletedCallBack, null);
        SetAsyncResult(result);
        return result;
    }
    public override void CompletedCallBack(IAsyncResult ar)
    {
        try
        {
            var result = _func2.EndInvoke(ar);
            SetResult(result);
        }
        catch (Exception exception)
        {
            CatchException(exception);
            SetResult(default(TResult));
        }
        ContinueAsync();
    }
}

Asynchronous 异步操作封装

ActionAsync和FuncAsync为异步操作打下了基础,接下来最重要的工作就是通过这两个类执行我们的异步操作,为此我封装了一个异步操作类
主要封装了以下几个部分：

1. WaitAll(IEnumerable operations):等待所有操作执行完毕
2. WaitAny(IEnumerable operations):等待任意操作执行完毕
3. ActionAsync
4. FuncAsync
5. ContinueWithAction

6. ContinueWithFunc

   后面四个包含若干个重载,这里只是笼统的代表一个类型的方法

   WaitAll

public static void WaitAll(IEnumerable operations)
{
    foreach (var @operator in operations)
    {
        @operator.Wait();
    }
}

WaitAny

public static void WaitAny(IEnumerable operations)
{
    while (operations.All(o => !o.Middle.IsCompleted))
        Thread.Sleep(100);
}

等待时间可以自定义

ActionInvoke

public static Operator Invoke(Action action)
{
    Operator operation = new ActionAsync(action);
    operation.Invoke();
    return operation;
}
public static Operator Invoke(Action action, T parameter)
{
    Operator operation = new ActionAsync(action, parameter);
    operation.Invoke();
    return operation;
}
public static Operator Invoke(Action action, T1 parameter1, T2 parameter2)
{
    Operator operation = new ActionAsync(action, parameter1, parameter2);
    operation.Invoke();
    return operation;
}

FuncInvoke

public static Operator Invoke(Func func)
{
    Operator operation = new FuncAsync(func);
    operation.Invoke();
    return operation;
}
public static Operator Invoke(Func func, TParameter parameter)
{
    TParameter param = parameter;
    Operator operation = new FuncAsync(func, param);
    operation.Invoke();
    return operation;
}
public static Operator Invoke(Func func, T1 parameter1, T2 parameter2)
{
    Operator operation = new FuncAsync(func, parameter1, parameter2);
    operation.Invoke();
    return operation;
}

ContinueWithAction

public static Operator ContinueWithAsync(IEnumerableoperators, Action action)
{
    return Invoke(WaitAll, operators)
        .ContinueWithAsync(action);
}
public static Operator ContinueWithAsync(IEnumerable operators, Action action, TParameter parameter)
{
    return Invoke(WaitAll, operators)
        .ContinueWithAsync(action, parameter);
}

ContinueWithFunc

public static Operator ContinueWithAsync(IEnumerable operators,Func func)
{
    return Invoke(WaitAll, operators)
        .ContinueWithAsync(func);
}
public static Operator ContinueWithAsync(IEnumerable operators, 
    Func func, TParameter parameter)
{
    return Invoke(WaitAll, operators)
        .ContinueWithAsync(func, parameter);
}

这里有个bug当调用ContinueWithAsync后无法调用Wait等待,本来Wait需要从前往后等待每个异步操作,但是测试了下不符合预期结果。不过理论上来说应该无需这样操作,ContinueWithAsync只是为了当上一个异步操作执行完毕时继续执行的异步操作,若要等待,那不如两个操作放到一起,最后再等待依然可以实现。

前面的都是单步异步操作的调用,若需要对某集合进行某个方法的异步操作,可以foreach遍历

public void ForeachAsync(IEnumerbale parameters)
{
    foreach(string p in parameters)
    {
        Asynchronous.Invoke(Tast,p);
    }
}
public void Test(string parameter)
{
    //TODO:做一些事
}

每次都需要去手写foreach,比较麻烦,因此实现类似于PLinq的并行计算方法实在有必要,不过有一点差别,PLinq是采用多核CPU进行并行计算,而我封装的仅仅遍历集合进行异步操作而已

ForeachAction

public static IEnumerable Foreach(IEnumerable items, Action action)
{
    return items.Select(t => Invoke(action, t)).ToList();
}

ForeachFunc

public static IEnumerable Foreach(IEnumerable items, Func func)
{
    return items.Select(parameter => Invoke(func, parameter)).ToList();
}

如何使用

• 无返回值异步方法调用

public void DoSomeThing()
{
    //TODO:
}

通过Asynchronous.Invoke(DoSomeThing) 执行

public void DoSomeThing(string parameter)
{
    //TODO:
}

通过Asynchronous.Invoke(DoSomeThing,parameter) 执行

• 有返回值异步方法调用

public string DoSomeThing()
{
    //TODO:
}

通过Asynchronous.Invoke(()=>DoSomeThing())执行

public string DoSomeThing(string parameter)
{
    //TODO:
}

通过Asynchronous.Invoke(()=>DoSomeThing(parameter))执行,或者也可以传入参数通过Asynchronous.Invoke(p=>DoSomeThing(p),parameter)

• 无返回值Foreach

public void Test
{
    int[] parameters = {1,2,3,4,5};
    Asynchronous.Foreach(parameters,Console.WriteLine);
}

• 有返回值Foreach

public void Test
{
    int[] parameters = {1,2,3,4,5};
    var operators = Asynchronous.Foreach(parameters,p=> p*2);
    Asynchrous.WaitAll(operators);
    Asynchronous.Foreach(operators.Cast>(),
        p=> Console.WriteLine(p.Result));
}

首先将集合每个值扩大2倍,然后输出

• 异步执行完再执行

public void Test
{
    int[] parameters = {1,2,3,4,5};
    var operators = Asynchronous.Foreach(parameters,p=> p*2);
    Asynchrous.ContinueWithAsync(operators,Console.WriteLine,"执行完成");
}

• 每次执行完继续执行
  可能有时候我们需要遍历一个集合,每个元素处理完成后我们需要输出XX处理完成

public void Test
{
    int[] parameters = {1,2,3,4,5};
    var operators = Asynchronous.Foreach(parameters,p=> p*2);
    Asynchronous.Foreach(operators,o=>{
        o.ContinueWithAsync(()={
            //每个元素执行完时执行
            if(o.Exception != null)
            {
                //之前执行时产生未处理的异常,这里可以捕获到  
            }
        });
    });
}

• 可以实现链式异步操作

public void Chain()
{
    Asynchronous.Invoke(Console.WriteLine,1)
    .ContinueWithAsync(Console.WriteLine,2)
    .ContinueWithAsync(Console.WriteLine,3)
}

这样会按步骤输出1,2,3

结束语

以上只是列出了部分重载方法,其他重载方法无非就是加参数,本质实际是一样的,具体可以已提交至github。我还封装了for方法,但是感觉没什么用,而且也从没有用到过,这里不再提
通过以上的封装,已经能完成日常大部分的操作,调用还是比较方便的。

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