问题描述

我注意到 control.BeginInvoke(delegate) 有时无法调用委托.我知道 BeginInvoke 只是创建一个 PostMessage 并且该消息稍后由应用程序处理(默认情况下发布消息限制为 10,000).鉴于我们的应用程序不是很复杂，是否还有其他原因导致它无法执行委托?我的代码如下所示.

I noticed that control.BeginInvoke(delegate) some times fail to call the delegate. I understand that BeginInvoke just creates a PostMessage and that message is handled by the application later (post message limit by default is 10,000). Given that our application is not very complex, Is there any other reason why it can fail to execute the delegate? My code is something like below.

class MyClass : Form{

    private bool executing = false;
    private delegate void DelegateBar(string info, int total, bool status, object obj);
    private void Bar(string info, int total, bool status, object obj){
        log("Enterning Bar");
        // Update something on UI
        executing = false;
        log("Exiting Bar");
    }
    public void foo(){
        log("Entering Foo");
        executing = true;
            try{
            // do something over the network
            }catch(Exception e){
                // probably network down. Lets not worry about it
            }
        DelegateBar barPtr = new DelegateBar(Bar);
        // Update UI .. call on form : form is a control
        this.BeginInvoke(barPtr, new object[] {"someInfo", 3, false, null});
        log("Exiting Fool");
    }

    public void callMeEveryFiveSeconds(){
        if(!executing) foo();
    }

    private delegate void DelegateCallMe();

    // execute every 5 seconds.
    private void timer1_Tick(object sender, EventArgs e)
    {
        Delegate del = new DelegateCallMe(callMeEveryFiveSeconds);
        // appoligies if syntax is not right, it to convey the idea that callMeEveryFiveSeconds is called on the main thread (asynchronously)
        this.beginInvoke(del, new object[]{});
    }
}

推荐答案

发布的代码对我来说看起来不错.如果这与您使用的代码不匹配，那么我建议您查找以下内容之一:

The code looks fine to me as posted. If this does not match your code in use then I would suggest looking for one of the following:

1) 如果您的消费任务需要更长的时间，那么 FiveSeconds 方法会显示每次都不会被调用

1) If your consuming task takes longer then the FiveSeconds method to give the appearance of not being called every time

2) 如果消费任务和Updating UI的组合导致方法的出现不是每次都被调用

2) If the combination of the consuming task and Updating the UI results in the appearance of the method not being called every time

3) 如果消费任务中未显示的任何代码可以改变执行的值(或退出方法，因为它可以设置为 false)

3) If any of the code not shown in the consuming task could alter the value of executing (or exit the method because it can be set to false)

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