MailboxProcessor.PostAndTryAsyncReply<'Msg,'Reply> 方法 (F#)

更新：2011 年 1 月

的 MailboxProcessor.AsyncPostAndReply，類似但傳回 None如果沒有回覆中的逾時期間。

命名空間/模組路徑： Microsoft.FSharp.Control

組件：FSharp.Core (在 FSharp.Core.dll 中)

// Signature:
member this.PostAndTryAsyncReply : (AsyncReplyChannel<'Reply> -> 'Msg) * ?int -> Async<'Reply option>

// Usage:
mailboxProcessor.PostAndTryAsyncReply (buildMessage)
mailboxProcessor.PostAndTryAsyncReply (buildMessage, timeout = timeout)

參數

• buildMessage
  型別：AsyncReplyChannel<'Reply> -> 'Msg

  的 AsyncReplyChannel 併入要傳送訊息至函式。

• timeout
  型別：int

  等待回應訊息的選擇性逾時參數 (以毫秒為單位)。 預設值為-1 會對應到 Infinite()

傳回值

會傳回回覆或 的非同步計算 ( 非同步 物件) None如果在逾時到期

範例

下列程式碼將示範如何使用 PostAndTryAsyncReply 方法。

open System

type Message = string * AsyncReplyChannel<string>

let formatString = "Message number {0} was received. Message contents: {1}"

let agent = MailboxProcessor<Message>.Start(fun inbox ->
    let rec loop n =
        async {          
            let! (message, replyChannel) = inbox.Receive();
            // The delay gets longer with each message, and eventually triggers a timeout.
            do! Async.Sleep(200 * n );
            if (message = "Stop") then
                replyChannel.Reply("Stop")
            else
                replyChannel.Reply(String.Format(formatString, n, message))
            do! loop (n + 1)
        }
    loop (0))

printfn "Mailbox Processor Test"
printfn "Type some text and press Enter to submit a message."
printfn "Type 'Stop' to close the program."

let mutable isCompleted = false
while (not isCompleted) do
    printf "> "
    let input = Console.ReadLine()
    let messageAsync = agent.PostAndTryAsyncReply((fun replyChannel -> input, replyChannel), 1000)
    // Set up a continuation function (the first argument below) that prints the reply.
    // The second argument is the exception continuation.
    // The third argument is the cancellation continuation (not used).
    Async.StartWithContinuations(messageAsync, 
         (fun reply -> 
             match reply with
             | None -> printfn "Reply timeout exceeded."
             | Some reply -> if (reply = "Stop") then
                                 isCompleted <- true
                             else printfn "%s" reply),
         (fun exn ->
            printfn "Exception occurred: %s" exn.Message),
         (fun _ -> ()))

printfn "Press Enter to continue."
Console.ReadLine() |> ignore

以下的範例工作階段。

平台

Windows 7、Windows Vista SP2、Windows XP SP3、Windows XP x64 SP2、Windows Server 2008 R2、Windows Server 2008 SP2、Windows Server 2003 SP2

版本資訊

F# 執行階段

支援版本：2.0、4.0

Silverlight

支援版本：3

請參閱

參考

Control.MailboxProcessor<'Msg> 類別 (F#)

Microsoft.FSharp.Control 命名空間 (F#)

變更記錄

日期	History	原因
2011 年 1 月	加入程式碼範例。	資訊加強。