我无法弄清楚为什么在调用GetTotal
时挂起以下代码。我似乎无法在MailboxProcessor内部进行调试,因此很难看到发生了什么。
module Aggregator
open System
type Message<'T, 'TState> =
| Aggregate of 'T
| GetTotal of AsyncReplyChannel<'TState>
type Aggregator<'T, 'TState>(initialState, f) =
let myAgent = new MailboxProcessor<Message<'T, 'TState>>(fun inbox ->
let rec loop agg =
async {
let! message = inbox.Receive()
match message with
| Aggregate x -> return! loop (f agg x)
| GetTotal replyChannel ->
replyChannel.Reply(agg)
return! loop agg
}
loop initialState
)
member m.Aggregate x = myAgent.Post(Aggregate(x))
member m.GetTotal = myAgent.PostAndReply(fun replyChannel -> GetTotal(replyChannel))
let myAggregator = new Aggregator<int, int>(0, (+))
myAggregator.Aggregate(3)
myAggregator.Aggregate(4)
myAggregator.Aggregate(5)
let totalSoFar = myAggregator.GetTotal
printfn "%d" totalSoFar
Console.ReadLine() |> ignore
直接使用相同的MailboxProcessor似乎工作正常,而不是包装在Aggregator
类中。
答案 0 :(得分:7)
问题是您没有启动代理。您可以在创建代理后调用Start
:
let myAgent = (...)
do myAgent.Start()
或者,您可以使用MailboxProcessor<'T>.Start
创建代理而不是调用构造函数(我通常更喜欢这个选项,因为它看起来更实用):
let myAgent = MailboxProcessor<Message<'T, 'TState>>.Start(fun inbox -> (...) )
我认为您无法调试代理,因为代理内部的代码实际上并未运行。我尝试在代理内部printfn "Msg: %A" message
调用后立即添加Receive
(打印传入的消息以进行调试),我注意到,在调用Aggregate
后,代理实际上没有收到任何消息...(仅在致电GetTotal
后才会被阻止,这有效回复)
作为旁注,我可能会将GetTotal
转换为方法,因此您需要调用GetTotal()
。每次访问属性时都会重新评估属性,因此您的代码执行相同的操作,但最佳做法不建议使用执行复杂工作的属性。
答案 1 :(得分:4)
您忘了启动邮箱:
open System
type Message<'T, 'TState> =
| Aggregate of 'T
| GetTotal of AsyncReplyChannel<'TState>
type Aggregator<'T, 'TState>(initialState, f) =
let myAgent = new MailboxProcessor<Message<'T, 'TState>>(fun inbox ->
let rec loop agg =
async {
let! message = inbox.Receive()
match message with
| Aggregate x -> return! loop (f agg x)
| GetTotal replyChannel ->
replyChannel.Reply(agg)
return! loop agg
}
loop initialState
)
member m.Aggregate x = myAgent.Post(Aggregate(x))
member m.GetTotal = myAgent.PostAndReply(fun replyChannel -> GetTotal(replyChannel))
member m.Start() = myAgent.Start()
let myAggregator = new Aggregator<int, int>(0, (+))
myAggregator.Start()
myAggregator.Aggregate(3)
myAggregator.Aggregate(4)
myAggregator.Aggregate(5)
let totalSoFar = myAggregator.GetTotal
printfn "%d" totalSoFar
Console.ReadLine() |> ignore