如何等待ExcelUtilAsync任务？

Question

Im using ExcelDNA for an addin. I have a few tasks running asychronously using ExcelUtilAsync.Run, but when they're all done, I want to run a function formatting all their output to return to excel. I tried using a Barrier, but it cannot return a value (I think, I'm new to c#). How do I await/join these tasks?

Answer 1

There's lots of ways to do that... Depending on how/when you want to wait for the completion.

A very simple way to do that (assuming you know how many tasks will run) would be to use a CountdownEvent . Something like this:

// Define how many tasks will be run via ExcelAsyncUtil
var countdownEvent = new CountdownEvent(2);

ExcelAsyncUtil.Run("Task1", null, handle =>
{
    try
    {
        // Do work for Task 1
    }
    finally
    {
        countdownEvent.Signal();
    }
});

ExcelAsyncUtil.Run("Task2", null, handle =>
{
    try
    {
        // Do work for Task 2
    }
    finally
    {
        countdownEvent.Signal();
    }
});

// Wait for all of them to finish (blocking)
countdownEvent.Wait();

// All async tasks have been completed
// (...)

You could also look at the AsyncAwaitMacro example in Excel-DNA: https://github.com/Excel-DNA/Samples/tree/master/AsyncAwaitMacro