Control.MailboxProcessor<'Msg> 類別 (F#)
可執行非同步計算的訊息處理代理程式。
命名空間/模組路徑：Microsoft.FSharp.Control
組件：FSharp.Core (在 FSharp.Core.dll 中)
[<Sealed>]
[<AutoSerializable(false)>]
type MailboxProcessor<'Msg> =
class
interface IDisposable
new MailboxProcessor : (MailboxProcessor<'Msg> -> Async<unit>) * ?CancellationToken -> MailboxProcessor<'Msg>
member this.Post : 'Msg -> unit
member this.PostAndAsyncReply : (AsyncReplyChannel<'Reply> -> 'Msg) * int option -> Async<'Reply>
member this.PostAndReply : (AsyncReplyChannel<'Reply> -> 'Msg) * int option -> 'Reply
member this.PostAndTryAsyncReply : (AsyncReplyChannel<'Reply> -> 'Msg) * ?int -> Async<'Reply option>
member this.Receive : ?int -> Async<'Msg>
member this.Scan : ('Msg -> Async<'T> option) * ?int -> Async<'T>
member this.Start : unit -> unit
static member Start : (MailboxProcessor<'Msg> -> Async<unit>) * ?CancellationToken -> MailboxProcessor<'Msg>
member this.TryPostAndReply : (AsyncReplyChannel<'Reply> -> 'Msg) * ?int -> 'Reply option
member this.TryReceive : ?int -> Async<'Msg option>
member this.TryScan : ('Msg -> Async<'T> option) * ?int -> Async<'T option>
member this.add_Error : Handler<Exception> -> unit
member this.CurrentQueueLength : int
member this.DefaultTimeout : int with get, set
member this.Error : IEvent<Exception>
member this.remove_Error : Handler<Exception> -> unit
end
備註
此代理程式會封裝可支援多重寫入器和單一讀取器代理程式的訊息佇列。 寫入器會使用 Post 方法與其變數，傳送訊息給代理程式。 此代理程式可以使用 Receive 或 TryReceive 方法等待訊息，或是使用 Scan 或 TryScan 方法掃描所有的可用訊息。
這個型別在 .NET 組件中名為 FSharpMailboxProcessor。 如果是透過 F# 以外的 .NET 語言存取型別，或透過反映存取型別，請使用這個名稱。
建構函式
成員 |
描述 |
|---|---|
建立代理程式。 body 函式會用來產生由代理程式執行的非同步計算。 在呼叫 Start 之前不會執行這個函式。 |
執行個體成員
成員 |
描述 |
|---|---|
執行代理程式而造成例外狀況時發生。 |
|
傳回代理程式之訊息佇列中的未處理訊息數目。 |
|
如果未在此時間內收到訊息，則會引發逾時例外狀況。 預設不會使用逾時。 |
|
執行代理程式而造成例外狀況時發生。 |
|
非同步將訊息發佈至 MailboxProcessor 的訊息佇列。 |
|
非同步將訊息發佈至代理程式，並在通道上等待回覆。 |
|
同步將訊息發佈至代理程式，並在通道上等待回覆。 |
|
與 AsyncPostAndReply 類似，但會在未於逾時期間內回覆時傳回 None。 |
|
等待訊息。 這將會使用第一個收到的訊息。 |
|
執行代理程式而造成例外狀況時發生。 |
|
在多個訊息內依照收到的順序掃描訊息，直到 scanner 傳回 Some 這個值為止。 其他訊息仍在佇列中。 |
|
啟動代理程式。 |
|
與 PostAndReply 類似，但會在未於逾時期間內回覆時傳回 None。 |
|
等待訊息。 這將會使用第一個收到的訊息。 |
|
在多個訊息內依照收到的順序掃描訊息，直到 scanner 傳回 Some 這個值為止。 其他訊息仍在佇列中。 |
靜態成員
成員 |
描述 |
|---|---|
建立並啟動代理程式。 body 函式會用來產生由代理程式執行的非同步計算。 |
範例
下列範例示範 MailboxProcessor 類別的基本用法。
open System
open Microsoft.FSharp.Control
type Message(id, contents) =
static let mutable count = 0
member this.ID = id
member this.Contents = contents
static member CreateMessage(contents) =
count <- count + 1
Message(count, contents)
let mailbox = new MailboxProcessor<Message>(fun inbox ->
let rec loop count =
async { printfn "Message count = %d. Waiting for next message." count
let! msg = inbox.Receive()
printfn "Message received. ID: %d Contents: %s" msg.ID msg.Contents
return! loop( count + 1) }
loop 0)
mailbox.Start()
mailbox.Post(Message.CreateMessage("ABC"))
mailbox.Post(Message.CreateMessage("XYZ"))
Console.WriteLine("Press any key...")
Console.ReadLine() |> ignore
範例輸出
下列範例示範如何使用 MailboxProcessor，建立簡單的代理程式以接受各種類型的郵件並傳回適當的回覆。 這個伺服器代理程式代表證券交易商，是為資產設定買入價和賣出價的證券交易所買賣經紀人。 用戶端可以查詢價格，或購買和賣出股票。
open System
type AssetCode = string
type Asset(code, bid, ask, initialQuantity) =
let mutable quantity = initialQuantity
member this.AssetCode = code
member this.Bid = bid
member this.Ask = ask
member this.Quantity with get() = quantity and set(value) = quantity <- value
type OrderType =
| Buy of AssetCode * int
| Sell of AssetCode * int
type Message =
| Query of AssetCode * AsyncReplyChannel<Reply>
| Order of OrderType * AsyncReplyChannel<Reply>
and Reply =
| Failure of string
| Info of Asset
| Notify of OrderType
let assets = [| new Asset("AAA", 10.0, 10.05, 1000000);
new Asset("BBB", 20.0, 20.10, 1000000);
new Asset("CCC", 30.0, 30.15, 1000000) |]
let codeAssetMap = assets
|> Array.map (fun asset -> (asset.AssetCode, asset))
|> Map.ofArray
let mutable totalCash = 00.00
let minCash = -1000000000.0
let maxTransaction = 1000000.0
let marketMaker = new MailboxProcessor<Message>(fun inbox ->
let rec Loop() =
async {
let! message = inbox.Receive()
match message with
| Query(assetCode, replyChannel) ->
match (Map.tryFind assetCode codeAssetMap) with
| Some asset ->
printfn "Replying with Info for %s" (asset.AssetCode)
replyChannel.Reply(Info(asset))
| None -> replyChannel.Reply(Failure("Asset code not found."))
| Order(order, replyChannel) ->
match order with
| Buy(assetCode, quantity) ->
match (Map.tryFind assetCode codeAssetMap) with
| Some asset ->
if (quantity < asset.Quantity) then
asset.Quantity <- asset.Quantity - quantity
totalCash <- totalCash + float quantity * asset.Ask
printfn "Replying with Notification:\nBought %d units of %s at price $%f. Total purchase $%f."
quantity asset.AssetCode asset.Ask (asset.Ask * float quantity)
printfn "Marketmaker balance: $%10.2f" totalCash
replyChannel.Reply(Notify(Buy(asset.AssetCode, quantity)))
else
printfn "Insufficient shares to fulfill order for %d units of %s."
quantity asset.AssetCode
replyChannel.Reply(Failure("Insufficient shares to fulfill order."))
| None -> replyChannel.Reply(Failure("Asset code not found."))
| Sell(assetCode, quantity) ->
match (Map.tryFind assetCode codeAssetMap) with
| Some asset ->
if (float quantity * asset.Bid <= maxTransaction && totalCash - float quantity * asset.Bid > minCash) then
asset.Quantity <- asset.Quantity + quantity
totalCash <- totalCash - float quantity * asset.Bid
printfn "Replying with Notification:\nSold %d units of %s at price $%f. Total sale $%f."
quantity asset.AssetCode asset.Bid (asset.Bid * float quantity)
printfn "Marketmaker balance: $%10.2f" totalCash
replyChannel.Reply(Notify(Sell(asset.AssetCode, quantity)))
else
printfn "Insufficient cash to fulfill order for %d units of %s."
quantity asset.AssetCode
replyChannel.Reply(Failure("Insufficient cash to cover order."))
| None -> replyChannel.Reply(Failure("Asset code not found."))
do! Loop()
}
Loop())
marketMaker.Start()
// Query price.
let reply1 = marketMaker.PostAndReply(fun replyChannel ->
printfn "Posting message for AAA"
Query("AAA", replyChannel))
// Test Buy Order.
let reply2 = marketMaker.PostAndReply(fun replyChannel ->
printfn "Posting message for BBB"
Order(Buy("BBB", 100), replyChannel))
// Test Sell Order.
let reply3 = marketMaker.PostAndReply(fun replyChannel ->
printfn "Posting message for CCC"
Order(Sell("CCC", 100), replyChannel))
// Test incorrect code.
let reply4 = marketMaker.PostAndReply(fun replyChannel ->
printfn "Posting message for WrongCode"
Order(Buy("WrongCode", 100), replyChannel))
// Test too large a number of shares.
let reply5 = marketMaker.PostAndReply(fun replyChannel ->
printfn "Posting message with large number of shares of AAA."
Order(Buy("AAA", 1000000000), replyChannel))
// Too large an amount of money for one transaction.
let reply6 = marketMaker.PostAndReply(fun replyChannel ->
printfn "Posting message with too large of a monetary amount."
Order(Sell("AAA", 100000000), replyChannel))
let random = new Random()
let nextTransaction() =
let buyOrSell = random.Next(2)
let asset = assets.[random.Next(3)]
let quantity = Array.init 3 (fun _ -> random.Next(1000)) |> Array.sum
match buyOrSell with
| n when n % 2 = 0 -> Buy(asset.AssetCode, quantity)
| _ -> Sell(asset.AssetCode, quantity)
let simulateOne() =
async {
let! reply = marketMaker.PostAndAsyncReply(fun replyChannel ->
let transaction = nextTransaction()
match transaction with
| Buy(assetCode, quantity) -> printfn "Posting BUY %s %d." assetCode quantity
| Sell(assetCode, quantity) -> printfn "Posting SELL %s %d." assetCode quantity
Order(transaction, replyChannel))
printfn "%s" (reply.ToString())
}
let simulate =
async {
while (true) do
do! simulateOne()
// Insert a delay so that you can see the results more easily.
do! Async.Sleep(1000)
}
Async.Start(simulate)
Console.WriteLine("Press any key...")
Console.ReadLine() |> ignore
範例輸出
平台
Windows 8 中， Windows 7， Windows Server 2012 上， Windows Server 2008 R2
版本資訊
F# 核心程式庫版本
支援版本:2.0， 4.0，可攜式執行檔 (PE)。