F# 需要有关异步和fsi的帮助吗
我想编写一些运行一系列F#脚本(.fsx)的代码。问题是,我可以有数百个脚本,如果我这样做:F# 需要有关异步和fsi的帮助吗,f#,sequence,asynchronous,f#-interactive,F#,Sequence,Asynchronous,F# Interactive,我想编写一些运行一系列F#脚本(.fsx)的代码。问题是,我可以有数百个脚本,如果我这样做: let shellExecute program args = let startInfo = new ProcessStartInfo() do startInfo.FileName <- program do startInfo.Arguments <- args do startInfo.UseShellExecute <
let shellExecute program args =
let startInfo = new ProcessStartInfo()
do startInfo.FileName <- program
do startInfo.Arguments <- args
do startInfo.UseShellExecute <- true
do startInfo.WindowStyle <- ProcessWindowStyle.Hidden
//do printfn "%s" startInfo.Arguments
let proc = Process.Start(startInfo)
()
scripts
|> Seq.iter (shellExecute "fsi")
fsx只是一个hello world脚本。
解决这个问题最惯用的方法是什么
我还想弄清楚,为每个正在执行的脚本检索一个返回代码是否可行,如果不可行,找到另一种方法。谢谢
编辑:
非常感谢您的见解和链接!我学到了很多。
我只想添加一些代码,以便使用Tomas建议的Async.parallel
并行运行批处理。如果mycut
功能有更好的实现,请发表意见
module Seq =
/// Returns a sequence of sequences of N elements from the source sequence.
/// If the length of the source sequence is not a multiple
/// of N, last element of the returned sequence will have a length
/// included between 1 and N-1.
let cut (count : int) (source : seq<´T>) =
let rec aux s length = seq {
if (length < count) then yield s
else
yield Seq.take count s
if (length <> count) then
yield! aux (Seq.skip count s) (length - count)
}
aux source (Seq.length source)
let batchCount = 2
let filesPerBatch =
let q = (scripts.Length / batchCount)
q + if scripts.Length % batchCount = 0 then 0 else 1
let batchs =
scripts
|> Seq.cut filesPerBatch
|> Seq.map Seq.toList
|> Seq.map loop
Async.RunSynchronously (Async.Parallel batchs) |> ignore
有趣的事情(正如Tomas所提到的)是,当进程终止时,Exited
事件似乎存储在某个地方,即使进程没有在EnableRaisingEvents
设置为true的情况下启动。
当此属性最终设置为true时,将触发事件
由于我不确定这是否是官方规范(也有点偏执),我找到了另一个解决方案,它包括在guard
函数中启动流程,因此我们确保代码在任何情况下都能工作:
let createStartInfo program args =
new ProcessStartInfo
(FileName = program, Arguments = args, UseShellExecute = false,
WindowStyle = ProcessWindowStyle.Normal,
RedirectStandardOutput = true)
let createProcess info =
let p = new Process()
do p.StartInfo <- info
do p.EnableRaisingEvents <- true
p
let rec loop scripts = async {
match scripts with
| [] -> printfn "FINISHED"
| script::scripts ->
let args = sprintf "\"%s\"" script
let p = createStartInfo "notepad" args |> createProcess
let! exit =
p.Exited
|> Event.guard (fun () -> p.Start() |> ignore)
|> Async.AwaitEvent
let output = p.StandardOutput.ReadToEnd()
do printfn "\nPROCESSED: %s, CODE: %d, OUTPUT: %A"script p.ExitCode output
return! loop scripts
}
让createStartInfo程序参数=
新流程StartInfo
(FileName=program,Arguments=args,UseShellExecute=false,
WindowsStyle=ProcessWindowsStyle.Normal,
重定向(标准输出=真)
让我们创建进程信息=
设p=newprocess()
p.StartInfo
让args=sprintf“\%s\”脚本
设p=createStartInfo“记事本”参数|>createProcess
让我来!出口=
p、 退出
|>Event.guard(fun()->p.Start()|>ignore)
|>异步事件
让output=p.StandardOutput.ReadToEnd()
是否打印fn“\n处理:%s,代码:%d,输出:%A”脚本p.ExitCode输出
回来!循环脚本
}
请注意,我已将fsi.exe替换为notepad.exe,这样我就可以在调试器中一步一步地重放不同的场景,并自己显式控制流程的退出。您的方法对我来说太棒了,我非常喜欢使用
waitevent
将流程执行嵌入异步工作流的想法
它不起作用的可能原因是,如果您想让它触发退出的事件,您需要将进程的enableringEvents
属性设置为true
(不要问我为什么要这样做,我觉得这很傻!),在测试您的代码时,我对其做了一些其他更改,因此这里有一个适合我的版本:
open System
open System.Diagnostics
let shellExecute program args =
// Configure process to redirect output (so that we can read it)
let startInfo =
new ProcessStartInfo
(FileName = program, Arguments = args, UseShellExecute = false,
WindowStyle = ProcessWindowStyle.Hidden,
RedirectStandardOutput = true)
// Start the process
// Note: We must enable rising events explicitly here!
Process.Start(startInfo, EnableRaisingEvents = true)
最重要的是,代码现在将EnableRaisingEvents
设置为true
。我还修改了代码,使用了一种语法,在构造对象时指定对象的属性(使代码更简洁),并修改了一些属性,以便可以读取输出(RedirectStandardOutput
)
现在,我们可以使用AwaitEvent
方法等待流程完成。我假设fsi
包含fsi.exe的路径,并且scripts
是FSX脚本的列表。如果要按顺序运行它们,可以使用使用递归实现的循环:
let rec loop scripts = async {
match scripts with
| [] -> printf "FINISHED"
| script::scripts ->
// Start the proces in background
let p = shellExecute fsi script
// Wait until the process completes
let! exit = Async.AwaitEvent p.Exited
// Read the output produced by the process, the exit code
// is available in the `ExitCode` property of `Process`
let output = p.StandardOutput.ReadToEnd()
printfn "\nPROCESSED: %s, CODE: %d\n%A" script p.ExitCode output
// Process the rest of the scripts
return! loop scripts }
// This starts the workflow on background thread, so that we can
// do other things in the meantime. You need to add `ReadLine`, so that
// the console application doesn't quit immedeiately
loop scripts |> Async.Start
Console.ReadLine() |> ignore
当然,您也可以并行运行这些进程(例如并行运行两组进程等),以使用Async.parallel
(通常的方式)
无论如何,这是一个非常好的例子,在一个我还没有看到使用异步工作流的领域中使用异步工作流。非常有趣:-)邮箱处理器怎么样 对于Tomas的回答,这是否是一个可行的解决方案,用于解决启动流程,然后订阅其退出的事件所涉及的竞争条件
type Process with
static member AsyncStart psi =
let proc = new Process(StartInfo = psi, EnableRaisingEvents = true)
let asyncExit = Async.AwaitEvent proc.Exited
async {
proc.Start() |> ignore
let! args = asyncExit
return proc
}
除非我弄错了,否则这将在启动流程之前订阅事件,并将其打包为Async
结果
这将允许您像这样重写其余的代码:
let shellExecute program args =
// Configure process to redirect output (so that we can read it)
let startInfo =
new ProcessStartInfo(FileName = program, Arguments = args,
UseShellExecute = false,
WindowStyle = ProcessWindowStyle.Hidden,
RedirectStandardOutput = true)
// Start the process
Process.AsyncStart(startInfo)
let fsi = "PATH TO FSI.EXE"
let rec loop scripts = async {
match scripts with
| [] -> printf "FINISHED"
| script::scripts ->
// Start the proces in background
use! p = shellExecute fsi script
// Read the output produced by the process, the exit code
// is available in the `ExitCode` property of `Process`
let output = p.StandardOutput.ReadToEnd()
printfn "\nPROCESSED: %s, CODE: %d\n%A" script p.ExitCode output
// Process the rest of the scripts
return! loop scripts
}
let rec loop scripts = async {
match scripts with
| [] -> printf "FINISHED"
| script::scripts ->
let p = shellExecute fsi script
let! exit =
p.Exited
|> Event.guard (fun () -> p.EnableRaisingEvents <- true)
|> Async.AwaitEvent
let output = p.StandardOutput.ReadToEnd()
return! loop scripts }
module Event =
let guard f (e:IEvent<'Del, 'Args>) =
let e = Event.map id e
{ new IEvent<'Args> with
member x.AddHandler(d) = e.AddHandler(d)
member x.RemoveHandler(d) = e.RemoveHandler(d); f()
member x.Subscribe(observer) =
let rm = e.Subscribe(observer) in f(); rm }
module Observable =
let guard f (e:IObservable<'Args>) =
{ new IObservable<'Args> with
member x.Subscribe(observer) =
let rm = e.Subscribe(observer) in f(); rm }
type SubjectState<'T> = Listen of ('T -> unit) list | Value of 'T
如果这样做的话,那么比起Vladimir的Async.GetSubject
我做了一些实验,这里有一种方法可以解决我帖子下面的评论和Joel的回答中讨论的问题(我认为目前不起作用,但可以解决)
我认为Process
的规范是,在我们将EnableRaisingEvents
属性设置为true
之后,它可以触发Exited
事件(并且将触发事件,即使在我们设置属性之前流程已经完成)。为了正确处理这种情况,我们需要在将处理程序附加到退出的事件之后启用事件的引发
这是一个问题,因为如果我们使用AwaitEvent
,它将阻止工作流,直到事件触发。从工作流中调用AwaitEvent
之后,我们无法执行任何操作(如果我们在调用AwaitEvent
之前设置了属性,那么我们将获得一场竞赛……)。是正确的,但我认为有一个更简单的方法来处理这个问题
我将创建一个函数Event.guard
获取一个事件并返回一个事件,它允许我们指定在将处理程序附加到事件后将执行的某些函数。这意味着,如果我们在这个函数中执行一些操作(这反过来会触发事件),事件将得到处理
要将它用于这里讨论的问题,我们需要如下更改我的原始解决方案。首先,shellExecute
函数不能设置EnableRaisingEvents
属性(否则,我们可能会丢失事件!)。其次,等待代码应如下所示:
let shellExecute program args =
// Configure process to redirect output (so that we can read it)
let startInfo =
new ProcessStartInfo(FileName = program, Arguments = args,
UseShellExecute = false,
WindowStyle = ProcessWindowStyle.Hidden,
RedirectStandardOutput = true)
// Start the process
Process.AsyncStart(startInfo)
let fsi = "PATH TO FSI.EXE"
let rec loop scripts = async {
match scripts with
| [] -> printf "FINISHED"
| script::scripts ->
// Start the proces in background
use! p = shellExecute fsi script
// Read the output produced by the process, the exit code
// is available in the `ExitCode` property of `Process`
let output = p.StandardOutput.ReadToEnd()
printfn "\nPROCESSED: %s, CODE: %d\n%A" script p.ExitCode output
// Process the rest of the scripts
return! loop scripts
}
let rec loop scripts = async {
match scripts with
| [] -> printf "FINISHED"
| script::scripts ->
let p = shellExecute fsi script
let! exit =
p.Exited
|> Event.guard (fun () -> p.EnableRaisingEvents <- true)
|> Async.AwaitEvent
let output = p.StandardOutput.ReadToEnd()
return! loop scripts }
module Event =
let guard f (e:IEvent<'Del, 'Args>) =
let e = Event.map id e
{ new IEvent<'Args> with
member x.AddHandler(d) = e.AddHandler(d)
member x.RemoveHandler(d) = e.RemoveHandler(d); f()
member x.Subscribe(observer) =
let rm = e.Subscribe(observer) in f(); rm }
module Observable =
let guard f (e:IObservable<'Args>) =
{ new IObservable<'Args> with
member x.Subscribe(observer) =
let rm = e.Subscribe(observer) in f(); rm }
type SubjectState<'T> = Listen of ('T -> unit) list | Value of 'T
好在这段代码非常简单。可以简化blogpost中主题的版本。getSubject可以返回工作流,而不是返回对事件的模拟