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

Article
02/19/2013

Comme MailboxProcessor.AsyncPostAndReply, mais retourne None s'il n'y a pas de réponse avant la fin de la période d'expiration.

Espace de noms/Chemin du module : Microsoft.FSharp.Control

Assembly : FSharp.Core (in FSharp.Core.dll)

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

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

Paramètres

buildMessage
Type : AsyncReplyChannel<'Reply> -> 'Msg

Fonction permettant d'incorporer AsyncReplyChannel dans le message à envoyer.
timeout
Type : int

Paramètre de délai d'attente facultatif (en millisecondes) d'un message de réponse.La valeur par défaut est -1, qui correspond à Infinite.

Valeur de retour

Un calcul asynchrone (objet Async) qui retournera la réponse ou None si le délai avant expiration est atteint.

Exemple

Le code suivant montre comment utiliser la méthode PostAndTryAsyncReply.

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

Un exemple de session suit.

Plateformes

Windows 8, Windows 7, Windows Server 2012, Windows Server 2008 R2

Informations de version

Versions de bibliothèque principale F#

Prise en charge dans : 2,0, 4,0, portables

Voir aussi

Référence

Control.MailboxProcessor<'Msg>, classe (F#)

Microsoft.FSharp.Control, espace de noms (F#)

Partager via