Interrupt Handling

Shows how to handle manual interrupt (i.e. CTRL+C) in a console application.

Note: similar (though not identical) techniques exist for other types of applications (e.g. desktop appplications, daemons, et cetera).

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#r "fszmq.dll"
open fszmq
open fszmq.Polling
open System.Threading

// helper to convert between frames to strings
let decode = System.Text.Encoding.ASCII.GetString

let main () =
  use context = new Context ()
  use replyer = Context.rep context
  Socket.bind replyer "tcp://*:5555"

  let interrupted = ref false
  System.Console.CancelKeyPress |> Event.add (fun e ->  interrupted := true
                                                        e.Cancel    <- true)

  use message = new Message ()
  while not !interrupted do
    if Message.tryRecv message replyer ZMQ.DONTWAIT then 
      let msg = decode <| Message.data message
      printfn "Received request: %s" msg
      // simulate work, by sleeping
      Thread.Sleep 1000
      // send reply back to client
      Socket.send replyer "World"B

  0 // return code

module docs

module PATH

from docs

val hijack : unit -> unit

Full name: docs.PATH.hijack

namespace fszmq

module Polling

from fszmq

namespace System

namespace System.Threading

val decode : (byte [] -> string)

Full name: Interrupt.decode

namespace System.Text

type Encoding =
  member BodyName : string
  member Clone : unit -> obj
  member CodePage : int
  member DecoderFallback : DecoderFallback with get, set
  member EncoderFallback : EncoderFallback with get, set
  member EncodingName : string
  member Equals : value:obj -> bool
  member GetByteCount : chars:char[] -> int + 3 overloads
  member GetBytes : chars:char[] -> byte[] + 5 overloads
  member GetCharCount : bytes:byte[] -> int + 2 overloads
  ...

Full name: System.Text.Encoding

property System.Text.Encoding.ASCII: System.Text.Encoding

System.Text.Encoding.GetString(bytes: byte []) : string
System.Text.Encoding.GetString(bytes: byte [], index: int, count: int) : string

val main : unit -> int

Full name: Interrupt.main

val context : System.IDisposable

val replyer : System.IDisposable

val interrupted : bool ref

Multiple items
val ref : value:'T -> 'T ref

Full name: Microsoft.FSharp.Core.Operators.ref

--------------------
type 'T ref = Ref<'T>

Full name: Microsoft.FSharp.Core.ref<_>

type Console =
  static member BackgroundColor : ConsoleColor with get, set
  static member Beep : unit -> unit + 1 overload
  static member BufferHeight : int with get, set
  static member BufferWidth : int with get, set
  static member CapsLock : bool
  static member Clear : unit -> unit
  static member CursorLeft : int with get, set
  static member CursorSize : int with get, set
  static member CursorTop : int with get, set
  static member CursorVisible : bool with get, set
  ...

Full name: System.Console

event System.Console.CancelKeyPress: IEvent<System.ConsoleCancelEventHandler,System.ConsoleCancelEventArgs>

Multiple items
module Event

from Microsoft.FSharp.Control

--------------------
type Event<'T> =
  new : unit -> Event<'T>
  member Trigger : arg:'T -> unit
  member Publish : IEvent<'T>

Full name: Microsoft.FSharp.Control.Event<_>

--------------------
type Event<'Delegate,'Args (requires delegate and 'Delegate :> Delegate)> =
  new : unit -> Event<'Delegate,'Args>
  member Trigger : sender:obj * args:'Args -> unit
  member Publish : IEvent<'Delegate,'Args>

Full name: Microsoft.FSharp.Control.Event<_,_>

--------------------
new : unit -> Event<'T>

--------------------
new : unit -> Event<'Delegate,'Args>

val add : callback:('T -> unit) -> sourceEvent:IEvent<'Del,'T> -> unit (requires delegate and 'Del :> System.Delegate)

Full name: Microsoft.FSharp.Control.Event.add

val e : System.ConsoleCancelEventArgs

property System.ConsoleCancelEventArgs.Cancel: bool

val message : System.IDisposable

val not : value:bool -> bool

Full name: Microsoft.FSharp.Core.Operators.not

val msg : string

val printfn : format:Printf.TextWriterFormat<'T> -> 'T

Full name: Microsoft.FSharp.Core.ExtraTopLevelOperators.printfn

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

--------------------
Thread(start: ThreadStart) : unit
Thread(start: ParameterizedThreadStart) : unit
Thread(start: ThreadStart, maxStackSize: int) : unit
Thread(start: ParameterizedThreadStart, maxStackSize: int) : unit

Thread.Sleep(timeout: System.TimeSpan) : unit
Thread.Sleep(millisecondsTimeout: int) : unit

val release : unit -> unit

Full name: docs.PATH.release