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Poll a file until it is quiet

One of the problems with using FileSystemWatcher to detect new files and process them is that it tells you when the file starts being created, not when it finishes. Use this little function to poll the file until it stops being written to.

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open System
open System.IO

// Wait until a file has completed copying, writing etc - if it exists at all:
let rec fileQuiet path =
    try
        if File.Exists(path) then
            use f = File.OpenRead(path)
            true
        else
            true // Change this if you want to know if the file didn't exist
    with
    | _ -> System.Threading.Thread.Sleep(1000)
           fileQuiet path
namespace System
namespace System.IO
val fileQuiet : path:string -> bool

Full name: Script.fileQuiet
val path : string
type File =
  static member AppendAllLines : path:string * contents:IEnumerable<string> -> unit + 1 overload
  static member AppendAllText : path:string * contents:string -> unit + 1 overload
  static member AppendText : path:string -> StreamWriter
  static member Copy : sourceFileName:string * destFileName:string -> unit + 1 overload
  static member Create : path:string -> FileStream + 3 overloads
  static member CreateText : path:string -> StreamWriter
  static member Decrypt : path:string -> unit
  static member Delete : path:string -> unit
  static member Encrypt : path:string -> unit
  static member Exists : path:string -> bool
  ...

Full name: System.IO.File
File.Exists(path: string) : bool
val f : FileStream
File.OpenRead(path: string) : FileStream
namespace System.Threading
Multiple items
type Thread =
  inherit CriticalFinalizerObject
  new : start:ThreadStart -> Thread + 3 overloads
  member Abort : unit -> unit + 1 overload
  member ApartmentState : ApartmentState with get, set
  member CurrentCulture : CultureInfo with get, set
  member CurrentUICulture : CultureInfo with get, set
  member DisableComObjectEagerCleanup : unit -> unit
  member ExecutionContext : ExecutionContext
  member GetApartmentState : unit -> ApartmentState
  member GetCompressedStack : unit -> CompressedStack
  member GetHashCode : unit -> int
  ...

Full name: System.Threading.Thread

--------------------
Threading.Thread(start: Threading.ThreadStart) : unit
Threading.Thread(start: Threading.ParameterizedThreadStart) : unit
Threading.Thread(start: Threading.ThreadStart, maxStackSize: int) : unit
Threading.Thread(start: Threading.ParameterizedThreadStart, maxStackSize: int) : unit
Threading.Thread.Sleep(timeout: TimeSpan) : unit
Threading.Thread.Sleep(millisecondsTimeout: int) : unit
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More information

Link:http://fssnip.net/b9
Posted:5 years ago
Author:Kit Eason
Tags: io , file handling