Question

    For Each account In _accounts11
        Dim newtask = account.readbalancesAsync()
        newtask = newtask.ContinueWith(Sub() account.LogFinishTask("Getting Balances", starttime))
        newtask = newtask.ContinueWith(Async Function() account.getOrdersAsync())
        newtask = newtask.ContinueWith(Sub() account.LogFinishTask("Getting Orders", starttime))

        tasklist.Add(newtask)
    Next


    Await Task.WhenAll(tasklist.ToArray)
    Dim b = 1

基本上，对于每个帐户，我想执行account.readbalancesAsync，然后再执行account.getOrdersAsync（）

我留下了代码newtask.ContinueWith(Sub() account.LogFinishTask("Getting Balances", starttime))，以表明我知道ContinueWith的工作原理。但是，在那之后，我需要继续执行另一项任务。

我该怎么做？

我想做的就是这样

    For Each account In _accounts11
        await account.readbalancesAsync()
        account.LogFinishTask("Getting Balances", starttime)
        await account.getOrdersAsync())
        account.LogFinishTask("Getting Orders", starttime)

        tasklist.Add(newtask)
    Next

很显然，如果我这样做，那么一个帐户必须等待另一个帐户完成。我希望所有帐户并行运行。

或者让我们看一下这段代码

dim response1 = await client.GetAsync("http://example.com/");
dim response2 = await client.GetAsync("http://stackoverflow.com/");

说我这样做

dim newtask = client.GetAsync("http://example.com/").continueWith(....)
await newtask

我应该在...里放什么。

Answer 1

我认为您在某个地方错误地转了弯。如果您需要一个接一个地运行这四个语句，但又不影响循环，那么您要做的就是创建一个执行多行/块lambda表达式的 one 任务。

例如：

For Each account In _accounts11
    Dim newtask = Task.Run( 'Start a new task.
        Async Function() 'Multiline lambda expression.
            Await account.readbalancesAsync()
            account.LogFinishTask("Getting Balances", starttime)
            Await account.getOrdersAsync()
            account.LogFinishTask("Getting Orders", starttime)
        End Function
    ) 'End of Task.Run()

    tasklist.Add(newtask)
Next

Answer 2

我只想在VisualVincent的答案中添加一些内容。我仍然更喜欢使用continueWith

Private Async Function readBalancesAndOrderForEachAccount(starttime As Long) As Task
    Await readbalancesAsync()
    LogFinishTask("Getting Balances", starttime)
    Await getOrdersAsync()
    LogFinishTask("Getting Orders", starttime)
End Function

Public Shared Async Function getMarketDetailFromAllExchangesAsync2() As Task
    Dim CurrentMethod = MethodBase.GetCurrentMethod().Name
    Dim tasklist = New List(Of Task)
    Dim starttime = jsonHelper.currentTimeStamp

...

        For Each account In _accounts11
            Dim newtask = account.readBalancesAndOrderForEachAccount(starttime)
            tasklist.Add(newtask)
        Next
        Await Task.WhenAll(tasklist.ToArray)
        Dim b = 1
   ...
    End Function

这似乎可行。但是，由于我很好奇，我想了解如何使用continueWith做到这一点。

如何在vb.net中执行另一个任务？

2 个答案: