Benutzer:MovGP0/F♯/Async
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Eventsopen System
let form = new Form(Text = "F# Events", Visible = true, TopMost = true)
// register Event Handler
form.Click.Add(fun args -> printfn "Clicked")
// filter events
form.MouseDown
|> Event.filter (fun args -> args.X < 50)
|> Event.map (fun args -> printfn "%d %d" args.X args.Y)
Application.Run(form)
Background Workersopen System.Threading
open System.ComponentModel
// define worker that can be cancelled
let worker = new BackgroundWorker(WorkerSupportsCancellation = true)
// define process that can be cancelled
worker.DoWork(fun args ->
for i in 1..50 do
if (worker.CancellationPending = false)
then
Thread.Sleep 1000
printf "%A" i
)
// define process that continues when cancelled
worker.DoWork.Add(fun args ->
for i in 1..10 do
Thread.Sleep 500
printfn "B: %A" i
)
worker.RunWorkerCompleted.Add(fun args -> printfn "Completed.")
// start worker
worker.RunWorkerAsync()
// cancel worker
Thread.Sleep 1500
worker.CancelAsync()
Threadsopen System.Threading
let thread = new Thread(fun () ->
for i in 1..10 do
try
Thread.Sleep 1000
with
| :? ThreadAbortException as ex -> prinfn "Exception %A" ex
printfn "I'm still running"
)
thread.Start ()
open System.Threading
let runMe () =
for i in 1..10 do
try
Thread.Sleep 1000
with
| :? ThreadAbortException as ex -> prinfn "Exception %A" ex
printfn "I'm still running"
let createThread () =
let thread = new Thread(runMe)
thread.Start ()
createThread()
createThread()
Thread Poolsopen System.Threading
let runMe (arg:object) =
for i in 1..10 do
try
Thread.Sleep 1000
with
| :? ThreadAboardException as ex -> printfn "Exception %A" ex
printfn "%A still running"
TreadPool.QueueUserWorkItem(new WaitCallback(runMe), "one")
TreadPool.QueueUserWorkItem(new WaitCallback(runMe), "two")
TreadPool.QueueUserWorkItem(new WaitCallback(runMe), "three")
Asynchronous Computing
// invoke Async.Start(fun () -> expression)
async {
expression
}
// invoke Async.Start(fun () -> expression)
let! response = request.GetResponseAsync()
open System
open System.Net
open Microsoft.FSharp.Control.WebExtensions
///<summary>Stock symbol and URL to Yahoo finance</summary>
let urlList = [
"MSFT", "http://ichart.finance.yahoo.com/table.csv?s=MSFT&d=6&e=6&f=2013&g=d&a=1&b=1&c=2010&ignore=.csv"
"GOOG", "http://ichart.finance.yahoo.com/table.csv?s=GOOG&d=6&e=6&f=2013&g=d&a=1&b=1&c=2010&ignore=.csv"
"EBAY", "http://ichart.finance.yahoo.com/table.csv?s=EBAY&d=6&e=6&f=2013&g=d&a=1&b=1&c=2010&ignore=.csv"
"AAPL", "http://ichart.finance.yahoo.com/table.csv?s=AAPL&d=6&e=6&f=2013&g=d&a=1&b=1&c=2010&ignore=.csv"
"ADBE", "http://ichart.finance.yahoo.com/table.csv?s=ADBE&d=6&e=6&f=2013&g=d&a=1&b=1&c=2010&ignore=.csv"
]
///<summary>Parse CSV and extract max price</summary>
let getMaxPrice (data:string) =
data.Split('\n')
|> Seq.skip 1
|> Seq.take (rows.Length - 2)
|> Seq.map (fun s -> s.Split(','))
|> Seq.map (fun s -> float s.[4]) // get price
|> Seq.max
///<summary>Async fetch of csv data</summary>
let fetchAsync (name, url:string) =
async {
try
let uri = new Uri(url)
let webClient = new WebClient()
let! csv = webClient.AsyncDownloadString uri
let maxPrice = getMaxPrice(csv.ToString())
printfn "Downloaded historical data for %s. Received %d characters. Max closing price since 2010-01-01 is %f" name csv.Length maxprice
with
| ex -> printfn "Exception: %s" ex.Message
}
let runAll () =
urlList
|> Seq.map fetchAsync
|> Async.Parallel
|> Async.RunSynchronously // wait till tasks are finished
|> ignore
runAll ()
Parallel Programming using TPL
Parallel.For
Parallel.ForEach
Parallel.Async
Parallel.Async [ asyncAction1, asyncAction2, ... ]
Mailbox Processor (Agent)
open System
type Agent<'T> = MailboxProcessor<'T>
type CounterMessage =
| Update of float
| Reset
module Helpers =
let genRandomNumber n =
let rnd = new Random()
float rnd.Next (n, 100)
module MaxAgent =
let sampleAgent = Agent.Start(fun inbox ->
let rec loop max = async {
let! msg = inbox.Receive()
match msg with
| Reset -> return! loop 0.0
| Update value ->
let max = Math.Max(max, value)
printfn "Max: %f" max
do! Async.Sleep 1000
return! loop max
}
loop 0.0
)
let agent = MaxAgent.sampleAgent
let random = Helpers.genRandomNumber 5
agent.Post(Update random)
References
|
