Handle a signal

Handle a signal
You are encouraged to solve this task according to the task description, using any language you may know.

Most operating systems provide interrupt facilities, sometimes called signals either generated by the user or as a result of program failure or reaching a limit like file space. Unhandled signals generally terminate a program in a disorderly manner. Signal handlers are created so that the program behaves in a well-defined manner upon receipt of a signal.

Task

Provide a program that displays an integer on each line of output at the rate of about one per half second. Upon receipt of the SIGINT signal (often generated by the user typing ctrl-C ( or better yet, SIGQUIT ctrl-\ )) the program will cease outputting integers, output the number of seconds the program has run, and then the program will quit.

Ada

Signal Handler

Ada signal handlers must be defined at the library level. The following package defines a simple signal handler for the SigInt signal.

with Ada.Interrupts; use Ada.Interrupts;
with Ada.Interrupts.Names; use Ada.Interrupts.Names;

package Sigint_Handler is
      protected Handler is
      entry Wait;
      procedure Handle;
      pragma Interrupt_Handler(Handle);
      pragma Attach_Handler(Handle, Sigint);
      private
      Call_Count : Natural := 0;
   end Handler;

end Sigint_Handler;

package body Sigint_Handler is

   -------------
   -- Handler --
   -------------

   protected body Handler is

      ----------
      -- Wait --
      ----------

      entry Wait when Call_Count > 0 is
      begin
         Call_Count := Call_Count - 1;
      end Wait;

      ------------
      -- Handle --
      ------------

      procedure Handle is
      begin
         Call_Count := Call_Count + 1;
      end Handle;

   end Handler;

end Sigint_Handler;

A signal may be received at any time in a program. Ada signal handling requires a task to suspend on an entry call for the handler which is executed only when the signal has been received. The following program uses the interrupt handler defined above to deal with receipt of SigInt.

with Ada.Calendar; use Ada.Calendar;
with Ada.Text_Io; use Ada.Text_Io;
with Sigint_Handler; use Sigint_Handler;

procedure Signals is
   task Counter is
      entry Stop;
   end Counter;
   task body Counter is
      Current_Count : Natural := 0;
   begin
      loop
         select
            accept Stop;
            exit;
         or delay 0.5;
         end select;
         Current_Count := Current_Count + 1;
         Put_Line(Natural'Image(Current_Count));
      end loop;
   end Counter;
   task Sig_Handler;
   
   task body Sig_Handler is
      Start_Time : Time := Clock;
      Sig_Time : Time;
   begin
      Handler.Wait;
      Sig_Time := Clock;
      Counter.Stop;
      Put_Line("Program execution took" & Duration'Image(Sig_Time - Start_Time) & " seconds");
   end Sig_Handler;
      
begin
   null;
         
end Signals;

Output:

 1
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 3
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 5
 6
 7
 8
Program execution took 4.348057086 seconds

AutoHotkey

Start:=A_TickCount
counter=0
SetTimer, timer, 500
return

timer:
Send % ++Counter "`n"
return

^c::
SetTimer, timer, off
SetFormat, float, 0.3
Send, % "Task took " (A_TickCount-Start)/1000 " Seconds"
ExitApp
return

Output:

1
2
3
4
5
6
Task took 3.526 Seconds

BaCon

' Handle signal
SUB Finished
    SIGNAL SIG_DFL, SIGINT    : ' Restore SIGINT to default
    PRINT "Running for", TIMER / 1000.0, "seconds" FORMAT "%s %f %s\n"
    STOP SIGINT               : ' Send another terminating SIGINT
ENDSUB

SIGNAL Finished, SIGINT
iter = 1
WHILE TRUE
    SLEEP 500
    PRINT iter
    iter = iter + 1
WEND

Output:

$ ./handle-signal
1
2
3
^CRunning for 1.766000 seconds

BBC BASIC

Works with: BBC BASIC for Windows

This program runs only in console mode; it must be compiled and then run as an EXE.

      REM!Exefile C:\bbcsigint.exe,encrypt,console
      INSTALL @lib$+"CALLBACK"
      CTRL_C_EVENT = 0
      
      SYS "GetStdHandle", -10 TO @hfile%(1)
      SYS "GetStdHandle", -11 TO @hfile%(2)
      *INPUT 13
      *OUTPUT 14
      ON ERROR PRINT REPORT$ : QUIT ERR
      
      CtrlC% = FALSE
      handler% = FN_callback(FNsigint(), 1)
      SYS FN_syscalls("SetConsoleCtrlHandler"), handler%, 1 TO !FN_systo(res%)
      IF res%=0 PRINT "Could not set SIGINT handler" : QUIT 1
      
      PRINT "Press Ctrl+C to test...."
      TIME = 0
      Time% = 50
      REPEAT
        WAIT 1
        IF TIME > Time% THEN
          PRINT Time%
          Time% += 50
        ENDIF
      UNTIL CtrlC%
      PRINT "Ctrl+C was pressed after "; TIME/100 " seconds."
      QUIT
      
      DEF FNsigint(T%)
      CASE T% OF
        WHEN CTRL_C_EVENT: CtrlC% = TRUE : = 1
      ENDCASE
      = 0

Output:

C:\>bbcsigint
Press Ctrl+C to test....
        50
       100
       150
       200
       250
Ctrl+C was pressed after 2.72 seconds.

C:\>

C

Library: POSIX

Standard C's sleep() only provides one-second resolution, so the POSIX usleep() function is used here. (POSIX is not needed for the actual signal handling part.)

#include <stdio.h>
#include <stdlib.h>	// for exit()
#include <signal.h>
#include <time.h>	// for clock()
#include <unistd.h>	// for POSIX usleep()

volatile sig_atomic_t gotint = 0;

void handleSigint() {
    /*
     * Signal safety: It is not safe to call clock(), printf(),
     * or exit() inside a signal handler. Instead, we set a flag.
     */
    gotint = 1;
}
 
int main() {
    clock_t startTime = clock();
    signal(SIGINT, handleSigint);
    int i=0;
    for (;;) {
        if (gotint)
            break;
        usleep(500000);
        if (gotint)
            break;
	printf("%d\n", ++i);
    }
    clock_t endTime = clock();
    double td = (endTime - startTime) / (double)CLOCKS_PER_SEC;
    printf("Program has run for %5.3f seconds\n", td);
    return 0;
}

Output:

1
2
3
Program has run for 1.953 seconds

C#

Signals in C# are called events, and are handled by attaching event handler functions to the event, which are called when the event is triggered.

using System; //DateTime, Console, Environment classes
class Program
{
    static DateTime start;
    static void Main(string[] args)
    {
        start = DateTime.Now;
        //Add event handler for Ctrl+C command
        Console.CancelKeyPress += new ConsoleCancelEventHandler(Console_CancelKeyPress);
        int counter = 0;
        while (true)
        {
            Console.WriteLine(++counter);
            System.Threading.Thread.Sleep(500);
        }
    }
    static void Console_CancelKeyPress(object sender, ConsoleCancelEventArgs e)
    {
        var end = DateTime.Now;
        Console.WriteLine("This program ran for {0:000.000} seconds.", (end - start).TotalMilliseconds / 1000);
        Environment.Exit(0);
    }
}

C++

Translation of: C

#include <chrono>
#include <csignal>
#include <ctime>
#include <iostream>
#include <thread>

volatile sig_atomic_t gotint = 0;

void handler(int signum) {
	// Set a flag for handling the signal, as other methods like printf are not safe here
	gotint = 1;
}

int main() {
	using namespace std;

	signal(SIGINT, handler);

	int i = 0;
	clock_t startTime = clock();
	while (true) {
		if (gotint) break;
		std::this_thread::sleep_for(std::chrono::milliseconds(500));
		if (gotint) break;
		cout << ++i << endl;
	}
	clock_t endTime = clock();

	double dt = (endTime - startTime) / (double)CLOCKS_PER_SEC;
	cout << "Program has run for " << dt << " seconds" << endl;

	return 0;
}

Clojure

(= (- Java verbosity) Clojure)

(require 'clojure.repl)

(def start (System/nanoTime))

(defn shutdown [_]
  (println "Received INT after"
           (/ (- (System/nanoTime) start) 1e9)
           "seconds.")
  (System/exit 0))

(clojure.repl/set-break-handler! shutdown)

(doseq [i (range)]
  (prn i)
  (Thread/sleep 500))

COBOL

Works with GnuCOBOL 2.0

       identification division.
       program-id. signals.
       data division.
       working-storage section.
       01 signal-flag  pic 9 external.
          88 signalled value 1.
       01 half-seconds usage binary-long.
       01 start-time   usage binary-c-long.
       01 end-time     usage binary-c-long.
       01 handler      usage program-pointer.
       01 SIGINT       constant as 2.

       procedure division.
       call "gettimeofday" using start-time null
       set handler to entry "handle-sigint"
       call "signal" using by value SIGINT by value handler

       perform until exit
           if signalled then exit perform end-if
           call "CBL_OC_NANOSLEEP" using 500000000
           if signalled then exit perform end-if
           add 1 to half-seconds
           display half-seconds
       end-perform

       call "gettimeofday" using end-time null
       subtract start-time from end-time
       display "Program ran for " end-time " seconds"
       goback.
       end program signals.

       identification division.
       program-id. handle-sigint.
       data division.
       working-storage section.
       01 signal-flag  pic 9 external.

       linkage section.
       01 the-signal   usage binary-long.

       procedure division using by value the-signal returning omitted.
       move 1 to signal-flag
       goback.
       end program handle-sigint.

Output:

prompt$ cobc -x -j signals.cob
+0000000001
+0000000002
+0000000003
+0000000004
+0000000005
^CProgram ran for +00000000000000000002 seconds
prompt$

Common Lisp

Each Common Lisp implementation will handle signals differently, although a multi-implementation approach can be done using cffi. The full list of signal number can be found on [1]. Tested on SBCL 1.2.7 and ECL 13.5.1.

(ql:quickload :cffi)

(defconstant +SIGINT+ 2)

(defmacro set-signal-handler (signo &body body)
  (let ((handler (gensym "HANDLER")))
    `(progn
       (cffi:defcallback ,handler :void ((signo :int))
         (declare (ignore signo))
         ,@body)
       (cffi:foreign-funcall "signal" :int ,signo :pointer (cffi:callback ,handler)))))

(defvar *initial* (get-internal-real-time))

(set-signal-handler +SIGINT+
  (format t "Ran for ~a seconds~&" (/ (- (get-internal-real-time) *initial*) internal-time-units-per-second))
  (quit))

(let ((i 0))
  (loop do
    (format t "~a~&" (incf i))
    (sleep 0.5)))

Output:

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5
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7
8
9
10
Ran for 4901/1000 seconds

Crystal

start = Time.utc
ch = Channel(Int32 | Symbol).new

spawn do
  i = 0
  loop do
    sleep 1
    ch.send(i += 1)
  end
end

Signal::INT.trap do
  Signal::INT.reset
  ch.send(:kill)
end

loop do
  x = ch.receive
  break if x == :kill
  puts x
end

elapsed = Time.utc - start
puts "Program has run for %5.3f seconds." % elapsed.total_seconds

1
2
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5
^CProgram has run for 5.093 seconds.

D

Translation of: C

import core.stdc.signal;
import core.thread;
import std.concurrency;
import std.datetime.stopwatch;
import std.stdio;

__gshared int gotint = 0;
extern(C) void handleSigint(int sig) nothrow @nogc @system {
    /*
     * Signal safety: It is not safe to call clock(), printf(),
     * or exit() inside a signal handler. Instead, we set a flag.
     */
    gotint = 1;
}

void main() {
    auto sw = StopWatch(AutoStart.yes);
    signal(SIGINT, &handleSigint);
    for (int i=0; !gotint;) {
        Thread.sleep(500_000.usecs);
        if (gotint) {
            break;
        }
        writeln(++i);
    }
    sw.stop();
    auto td = sw.peek();
    writeln("Program has run for ", td);
}

Output:

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7
8
9
Program has run for 5 secs, 4 ms, 357 ╬╝s, and 4 hnsecs

Erlang

#! /usr/bin/env escript

main([]) ->
    erlang:unregister(erl_signal_server),
    erlang:register(erl_signal_server, self()),
    Start = seconds(),
    os:set_signal(sigquit, handle),
    Pid = spawn(fun() -> output_loop(1) end),
    receive
        {notify, sigquit} ->
            erlang:exit(Pid, normal),
            Seconds = seconds() - Start,
            io:format("Program has run for ~b seconds~n", [Seconds])
    end.

seconds() ->
    calendar:datetime_to_gregorian_seconds({date(),time()}).

output_loop(N) ->
    io:format("~b~n",[N]),
    timer:sleep(500),
    output_loop(N + 1).

F#

open System

let rec loop n = Console.WriteLine( n:int )
                 Threading.Thread.Sleep( 500 )
                 loop (n + 1)

let main() =
   let start = DateTime.Now
   Console.CancelKeyPress.Add(
      fun _ -> let span = DateTime.Now - start
               printfn "Program has run for %.0f seconds" span.TotalSeconds
             )
   loop 1

main()

Forth

Works with: GNU Forth

Normally Gforth handles most signals (e.g., the user interrupt SIGINT, or the segmentation violation SIGSEGV) by translating it into a Forth THROW.

-28 constant SIGINT

: numbers ( n -- n' )
  begin dup . cr  1+  500 ms again ;

: main
  utime
  0 begin
    ['] numbers catch
    SIGINT =
  until drop
  utime d- dnegate
  <# # # # # # # [char] . hold #s #> type ."  seconds" ;

main bye

Fortran

Works with: gfortran

Must be compiled with the -fcoarray=single flag to enable use of atomic operations.

program signal_handling
  use, intrinsic :: iso_fortran_env, only: atomic_logical_kind
  implicit none

  interface
    integer(C_INT) function usleep(microseconds) bind(c)
      use, intrinsic :: iso_c_binding, only: C_INT, C_INT32_T
      integer(C_INT32_T), value :: microseconds
    end function usleep
  end interface

  integer, parameter :: half_second = 500000
  integer, parameter :: sigint = 2
  integer, parameter :: sigquit = 3

  logical(atomic_logical_kind) :: interrupt_received[*]
  integer :: half_seconds
  logical :: interrupt_received_ref

  interrupt_received = .false.
  half_seconds = 0

  ! "Install" the same signal handler for both SIGINT and SIGQUIT.
  call signal(sigint, signal_handler)
  call signal(sigquit, signal_handler)

  ! Indefinite loop (until one of the two signals are received).
  do
    if (usleep(half_second) == -1) &
      print *, "Call to usleep interrupted."

    call atomic_ref(interrupt_received_ref, interrupt_received)
    if (interrupt_received_ref) then
      print "(A,I0,A)", "Program ran for ", half_seconds / 2, " second(s)."
      stop
    end if

    half_seconds = half_seconds + 1
    print "(I0)", half_seconds
  end do

contains

  subroutine signal_handler(sig_num)
    use, intrinsic :: iso_c_binding, only: C_INT
    integer(C_INT), value, intent(in) :: sig_num
    ! Must be declared with attribute `value` to force pass-by-value semantics
    ! (what C uses by default).

    select case (sig_num)
      case (sigint)
        print *, "Received SIGINT."
      case (sigquit)
        print *, "Received SIGQUIT."
    end select

    call atomic_define(interrupt_received, .true.)
  end subroutine signal_handler

end program signal_handling

FreeBASIC

Dim Shared As Double start
start = Timer

Dim As Integer n = 1
Dim As String s
Do	
    Print n
    s = Inkey
    If s = Chr(255) + "k" Then
        Dim As Double elapsed = Timer- start + n * 0.5
        Print Using "Program has run for & seconds."; elapsed
        End
    Else
        Sleep 500, 1
        n += 1
    End If
Loop

Gambas

hTimer As Timer
fTime As Float

Public Sub Application_Signal(x As Integer)

Print "Program stopped after " & fTime & " seconds"
Quit

End
 
Public Sub Main()
 
hTimer = New Timer As "IntTimer"

Print "Press [Ctrl] + " & Chr(92) & " to stop"

Signal[Signal.SIGQUIT].Catch
 
With hTimer
  .Delay = 500
  .Start
End With

End
 
Public Sub IntTimer_Timer()

Print Rand(0, 100)
fTime += 0.5

End

Output:

Press [Ctrl] + \ to stop
29
86
67
56
46
90
0
27
94
87
40
^\Program stopped after 5.5 seconds

Go

package main

import (
    "fmt"
    "os"
    "os/signal"
    "time"
)

func main() {
    start := time.Now()
    k := time.Tick(time.Second / 2)
    sc := make(chan os.Signal, 1)
    signal.Notify(sc, os.Interrupt)
    for n := 1; ; {
        // not busy waiting, this blocks until one of the two
        // channel operations is possible
        select {
        case <-k:
            fmt.Println(n)
            n++
        case <-sc:
            fmt.Printf("Ran for %f seconds.\n",
                time.Now().Sub(start).Seconds())
            return
        }
    }
}

Output:

1
2
3
^C
Ran for 1.804877 seconds.

Haskell

import Prelude hiding (catch)
import Control.Exception (catch, throwIO, AsyncException(UserInterrupt))
import Data.Time.Clock (getCurrentTime, diffUTCTime)
import Control.Concurrent (threadDelay)

main = do t0 <- getCurrentTime
          catch (loop 0)
                (\e -> if e == UserInterrupt
                         then do t1 <- getCurrentTime
                                 putStrLn ("\nTime: " ++ show (diffUTCTime t1 t0))
                         else throwIO e)

loop i = do print i
            threadDelay 500000 {- µs -}
            loop (i + 1)

HicEst

Subroutines "F2" to "F9" can be called any time by the F2...F9 keys or by a mouse click on the toolbar buttons "F2" to "F9". These buttons appear as soon as a SUBROUTINE "F2" to "F9" statement is compiled:

seconds = TIME()

DO i = 1, 1E100      ! "forever"
  SYSTEM(WAIT = 500) ! milli seconds
  WRITE(Name) i
ENDDO

SUBROUTINE F2        ! call by either the F2 key, or by a toolbar-F2 click
   seconds = TIME() - seconds
   WRITE(Messagebox, Name) seconds
   ALARM(999)        ! quit immediately
END

Icon and Unicon

The following works in Unicon. I don't know if it works in Icon.

global startTime

procedure main()
    startTime := &now
    trap("SIGINT", handler)
    every write(seq()) do delay(500)
end

procedure handler(s)
    stop("\n",&now-startTime," seconds")
end

Sample run:

->signal
1
2
3
4
^C
2 seconds
->

Java

Use of sun.misc.SignalHandler allows one to specify which signal to catch, though is unsupported and potentially not available in all JVMs

import sun.misc.Signal;
import sun.misc.SignalHandler;

public class ExampleSignalHandler {
    public static void main(String... args) throws InterruptedException {
        final long start = System.nanoTime();
        Signal.handle(new Signal("INT"), new SignalHandler() {
            public void handle(Signal sig) {
                System.out.format("\nProgram execution took %f seconds\n", (System.nanoTime() - start) / 1e9f);
                System.exit(0);
            }
        });
        int counter = 0;
        while(true) {
            System.out.println(counter++);
            Thread.sleep(500);
        }
    }
}

Or one can use a generic shutdown hook as follows, though a reference to the particular signal is not available.

public class ExampleSignalHandler {
    public static void main(String... args) throws InterruptedException {
        final long start = System.nanoTime();
        Runtime.getRuntime().addShutdownHook(new Thread(new Runnable() {
            public void run() {
                System.out.format("\nProgram execution took %f seconds\n", (System.nanoTime() - start) / 1e9f);
            }
        }));
        int counter = 0;
        while(true) {
            System.out.println(counter++);
            Thread.sleep(500);
        }
    }
}

Output:

node hsignal.js
1
2
3
4
5
6
7
8
9
4.5 seconds elapsed

JavaScript

Based on NodeJS interpreter/engine

(function(){
    var count=0
        secs=0
    
    var i= setInterval( function (){
        count++
        secs+=0.5
        console.log(count)
    }, 500);
    
    process.on('SIGINT', function() {
        clearInterval(i)
        console.log(secs+' seconds elapsed');
        process.exit()
    });
})();

Output:

node hsignal.js
1
2
3
4
5
6
7
8
9
4.5 seconds elapsed

Jsish

/* Handle a signal, is jsish */

var gotime = strptime();
var looping = true;
var loops = 1;

function handler() {
    printf("Elapsed time: %ds\n", (strptime() - gotime) / 1000);
    looping = false;
}

Signal.callback(handler, 'SIGINT');
Signal.handle('SIGINT');

while (looping) {
    puts(loops++);
    Event.update(500);
}

Event.update(500) causes the event loop to be monitored for 500 milliseconds, sleeping when there are no events to process for the given interval. 0 would return immediately.

Output:

prompt$ jsish
Jsish interactive: see 'help [cmd]'
# source('handle-signal.jsi');
1
2
3
4
5
^CElapsed time: 2s
# 

Julia

ccall(:jl_exit_on_sigint, Cvoid, (Cint,), 0)

function timeit()
    ticks = 0
    try
        while true
            sleep(0.5)
            ticks += 1
            println(ticks)
        end
    catch
    end
end

@time timeit()
println("Done.")

The tricky bit for this task is the ccall, which tells the main() running Julia to pass SIGINT on to Julia as an error. This call is not needed when running this code in Julia's REPL, which has the desired behavior by default.

Output:

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2
3
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5
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7
8
9
10
11
  6.020844 seconds (32.06 k allocations: 1.658 MiB)
Done.

Kotlin

// version 1.1.3

import sun.misc.Signal
import sun.misc.SignalHandler

fun main(args: Array<String>) {
    val startTime = System.currentTimeMillis()

    Signal.handle(Signal("INT"), object : SignalHandler {
        override fun handle(sig: Signal) {
            val elapsedTime = (System.currentTimeMillis() - startTime) / 1000.0
            println("\nThe program has run for $elapsedTime seconds")
            System.exit(0)
        }
    })

    var i = 0
    while(true) {  
        println(i++)      
        Thread.sleep(500)        
    }
}

Sample output:

0
1
2
3
4
5
6
7
8
9
10
^C
The program has run for 5.087 seconds

Liberty BASIC

Liberty BASIC cannot react to a SigInt signal and truly kill itself. The best it can do is respond to Ctrl-C by exiting normally.

nomainwin
WindowHeight=DisplayHeight
open "Handle a signal" for graphics as #1
#1 "trapclose [quit]"
#1 "down;setfocus;place 10 20"
#1 "\Press CTRL + C to stop."
#1 "when characterInput [keyPressed]"
start=time$("ms")
timer 500, [doPrint]
wait
[quit] close #1:end

[doPrint]
  if sigInt then
    timer 0
    #1 "\Seconds elapsed: ";(time$("ms")-start)/1000
   else
    i=i+1
    if i mod 20 = 0 then #1 "cls;place 10 20"
    #1 "\";i
  end if
  wait

[keyPressed]
  if len(Inkey$)>1 then
    if left$(Inkey$,1)=chr$(8) then sigCtrl=1 else sigCtrl=0
  end if
  if sigCtrl=1 and Inkey$=chr$(3) then sigInt=1
  wait

Lua

local start_date = os.time()

local loop = true
local Exit = function ()
	print()
	loop = false
end

local posix = require"posix"
posix.signal(posix.SIGINT, Exit)
posix.signal(posix.SIGQUIT, Exit)

local int = 0
while loop do
	int = int+1
	print(int)
	posix.time.nanosleep{tv_sec=0,tv_nsec=500*1000*1000}
end

print(os.time() - start_date)

Output:

MATLAB

MATLAB versions 6.5 (R13) and newer can no longer catch CTRL+C with a try-catch block. The onCleanup() function was introduced in version 7.6 (R2008a), possibly specifically for this situation. However, the designated onCleanup() function will execute no matter how the function ends (task completion, CTRL+C, exception), and CTRL+C will still cause an exception to be thrown and displayed.

Works with: MATLAB version 7.6 (R2008a) and later

function sigintHandle
    k = 1;
    tic
    catchObj = onCleanup(@toc);
    while true
        pause(0.5)
        fprintf('%d\n', k)
        k = k+1;
    end
end

Output:

>> sigintCleanup
1
2
3
4
5
6
Elapsed time is 3.348772 seconds.
??? Operation terminated by user during ==> sigintHandle at 6

Works with: MATLAB version 6.1 (R12.1) and earlier

This example is untested. Please check that it's correct, debug it as necessary, and remove this message.

function sigintHandle
    k = 1;
    tic
    try
        while true
            pause(0.5)
            fprintf('%d\n', k)
            k = k+1;
        end
    catch me
        toc
        rethrow me
    end
end

NewLISP

; Mac OSX, BSDs or Linux only, not Windows
(setq start-time (now))

(signal 2 (lambda()
            (println
             (format "Program has run for %d seconds"
                     (- (apply date-value (now))
                        (apply date-value start-time))))
            (exit 0)))

(while (println (++ i))
  (sleep 500))

Nim

import times, os, strutils

let t = epochTime()

proc handler() {.noconv.} =
  echo "Program has run for ", formatFloat(epochTime() - t, precision = 0), " seconds."
  quit 0

setControlCHook(handler)

for n in 1 ..< int64.high:
  sleep 500
  echo n

Or if you prefer an exception to be thrown on SIGINT:

import times, os, strutils

type EKeyboardInterrupt = object of CatchableError

proc handler() {.noconv.} =
  raise newException(EKeyboardInterrupt, "Keyboard Interrupt")

setControlCHook(handler)

let t = epochTime()

try:
  for n in 1 ..< int64.high:
    sleep 500
    echo n
except EKeyboardInterrupt:
  echo "Program has run for ", formatFloat(epochTime() - t, precision = 0), " seconds."

OCaml

OCaml's Unix.sleep doesn't handle non-integral arguments, so this program prints a number every second.

#load "unix.cma";; (* for sleep and gettimeofday; not needed for the signals stuff per se *)

let start = Unix.gettimeofday ();;

Sys.set_signal Sys.sigint
  (Sys.Signal_handle (fun _signum ->
                        Printf.printf "Ran for %f seconds.\n"
                          (Unix.gettimeofday () -. start);
                        exit 0));;

let rec loop n =
  Printf.printf "%d\n%!" n;
  Unix.sleep 1;
  loop (n + 1)
in
  loop 1;;

Perl

Before version 5.8 sleep requires an integer argument, so we'll spin (There exist more obtuse methods)

my $start = time;  # seconds since epohc
my $arlm=5;  # every 5 seconds show how we're doing
my $i;

$SIG{QUIT} = sub
   {print " Ran for ", time - $start, " seconds.\n"; die; };
$SIG{INT} = sub
   {print " Running for ", time - $start, " seconds.\n"; };
$SIG{ALRM} = sub
   {print " After $arlm  seconds i= $i. Executing for ",  time - $start, " seconds.\n";  alarm $arlm };


alarm $arlm;  # trigger ALaRM after we've run  for a while

print " ^C to inerrupt, ^\\ to quit, takes a break at $arlm seconds \n";

while ( 1 ) {
   for ( $w=11935000; $w--; $w>0 ){}; # spinning is bad, but hey it's only a demo

    print (  ++$i," \n");
            }

^C to inerrupt, ^\ to quit, takes a break at 5 seconds

1 2 ^C Running for 1 seconds. 3 4 ^C Running for 2 seconds. 5 6 7 ^C Running for 3 seconds. 8 9 10

After 5  seconds i= 10. Executing for 5 seconds.

11 12 13 14 15 16 17 18 19 20

After 5  seconds i= 20. Executing for 10 seconds.

21 22 ^\ Ran for 11 seconds. Died at 0.pl line 6..

This example does the required task:

use 5.010;
use AnyEvent;
my $start = AE::time;
my $exit = AE::cv;
my $int = AE::signal 'INT', $exit;
my $n;
my $num = AE::timer 0, 0.5, sub { say $n++ };
$exit->recv;
say " interrupted after ", AE::time - $start, " seconds";

Output:

0
1
2
3
4
5
6
7
8
9
10
^C interrupted after 5.23734092712402 seconds

Phix

See builtins\pbreak.e for the low-level (inline assembly) cross platform signal handler, and implementation of the standard hll allow_break() and check_break() routines

without js
allow_break(false)   -- by default Ctrl C terminates the program
puts(1,"Press Ctrl C\n")
atom t = time()
integer i = 1
while 1 do
    sleep(0.5)
    ?i
    if check_break() then exit end if
    i += 1
end while
printf(1,"The program has run for %3.2f seconds\n",{time()-t})

Output:

Press Ctrl C
1
2
3
The program has run for 1.53 seconds

PHP

Translation of: Perl

<?php
declare(ticks = 1);

$start = microtime(true);

function mySigHandler() {
  global $start;
  $elapsed = microtime(true) - $start;
  echo "Ran for $elapsed seconds.\n";
  exit();
}

pcntl_signal(SIGINT, 'mySigHandler');

for ($n = 0; ; usleep(500000)) // 0.5 seconds
   echo ++$n, "\n";
?>

PicoLisp

Put the following into a file, set it to executable, and run it

#!/usr/bin/picolisp /usr/lib/picolisp/lib.l

(push '*Bye '(println (*/ (usec) 1000000)) '(prinl))

(let Cnt 0
   (loop
      (println (inc 'Cnt))
      (wait 500) ) )

PL/I

handler: procedure options (main);
   declare i fixed binary (31);
   declare (start_time, finish_time) float (18);
   on attention begin;
      finish_time = secs();
      put skip list ('elapsed time =', finish_time - start_time, 'secs');
      stop;
   end;

   start_time = secs();
   do i = 1 by 1;
      delay (500);
      put skip list (i);
   end;
end handler;

PowerShell

$Start_Time = (Get-date).second
Write-Host "Type CTRL-C to Terminate..."
$n = 1
Try
{
    While($true)
    {
        Write-Host $n
        $n ++
        Start-Sleep -m 500
    }
}
Finally
{
    $End_Time = (Get-date).second
    $Time_Diff = $End_Time - $Start_Time
    Write-Host "Total time in seconds"$Time_Diff
}

Output:

PS F:\> . .\signal.ps1
Type CTRL-C to Terminate...
1
2
3
4
5
Total time in seconds 2

PureBasic

This code is for Windows only due to the usage of SetConsoleCtrlHandler()

CompilerIf #PB_Compiler_OS<>#PB_OS_Windows
  CompilerError "This code is Windows only"
CompilerEndIf

Global Quit, i, T0=ElapsedMilliseconds(), T1

Procedure CtrlC()
  T1=ElapsedMilliseconds()
  Quit=1
  While i: Delay(1): Wend 
EndProcedure

If OpenConsole() 
  SetConsoleCtrlHandler_(@CtrlC(),#True)  
  While Not Quit
    PrintN(Str(i))
    i+1
    Delay(500)
  Wend
  PrintN("Program has run for "+StrF((T1-T0)/1000,3)+" seconds.")
  Print ("Press ENTER to exit."):Input(): i=0
EndIf

0
1
2
3
4
Program has run for 2.121 seconds.
Press ENTER to exit.

Python

Simple version

import time

def counter():
    n = 0
    t1 = time.time()
    while True:
        try:
            time.sleep(0.5)
            n += 1
            print n
        except KeyboardInterrupt, e:
            print 'Program has run for %5.3f seconds.' % (time.time() - t1)
            break

counter()

The following example should work on all platforms.

import time

def intrptWIN():
   procDone = False
   n = 0

   while not procDone:
      try:
         time.sleep(0.5)
         n += 1
         print n
      except KeyboardInterrupt, e:
         procDone = True

t1 = time.time()
intrptWIN()
tdelt = time.time() - t1
print 'Program has run for %5.3f seconds.' % tdelt

There is a signal module in the standard distribution that accomodates the UNIX type signal mechanism. However the pause() mechanism is not implemented on Windows versions.

import signal, time, threading
done = False
n = 0

def counter():
   global n, timer
   n += 1
   print n
   timer = threading.Timer(0.5, counter)
   timer.start()

def sigIntHandler(signum, frame):
   global done
   timer.cancel()
   done = True

def intrptUNIX():
   global timer
   signal.signal(signal.SIGINT, sigIntHandler)

   timer = threading.Timer(0.5, counter)
   timer.start()
   while not done:
      signal.pause()

t1 = time.time()
intrptUNIX()
tdelt = time.time() - t1
print 'Program has run for %5.3f seconds.' % tdelt

How about this one? It should work on all platforms; and it does show how to install a signal handler:

import time, signal

class WeAreDoneException(Exception):
    pass

def sigIntHandler(signum, frame):
    signal.signal(signal.SIGINT, signal.SIG_DFL) # resets to default handler
    raise WeAreDoneException

t1 = time.time()

try:
    signal.signal(signal.SIGINT, sigIntHandler)
    n = 0
    while True:
        time.sleep(0.5)
        n += 1
        print n
except WeAreDoneException:
    pass

tdelt = time.time() - t1
print 'Program has run for %5.3f seconds.' % tdelt

Racket

#lang racket
(define now current-milliseconds)
(define start (now))
(with-handlers ([exn:break? 
                 (λ(x)
                   (define elapsed (/ (- (now) start) 1000.))
                   (displayln (~a "Total time: " elapsed)))])
  (for ([i (in-naturals)])
    (displayln i)
    (sleep 0.5)))

Output:

0
1
2
3
4
5
6
7
Total time: 3.965

Raku

(formerly Perl 6) We note with glee that the task does not require us to print consecutive integers, so we'll print Fibonacci numbers instead. :-)

signal(SIGINT).tap: {
    note "Took { now - INIT now } seconds.";
    exit;
}

for 0, 1, *+* ... * {
    sleep 0.5;
    .say;
}

Output:

0
1
1
2
3
5
8
13
21
34
55
89
^CTook 6.3437449 seconds.
Aborted

REXX

REXX has no   sleep   function that is built into the language.

Some operating systems that REXX runs under have a   SLEEP   or equivalent BIF.

But, there's more than one way to skin a cat.   (No offense to cat lovers.)

/*REXX program displays integers until a   Ctrl─C  is pressed, then shows the number of */
/*────────────────────────────────── seconds that have elapsed since start of execution.*/
call time 'Reset'                                /*reset the REXX elapsed timer.        */
signal on halt                                   /*HALT: signaled via a  Ctrl─C  in DOS.*/

   do j=1                                        /*start with  unity  and go ye forth.  */
   say right(j,20)                               /*display the integer right-justified. */
   t=time('E')                                   /*get the REXX elapsed time in seconds.*/
                do forever;   u=time('Elapsed')  /* "   "    "     "      "   "    "    */
                if u<t | u>t+.5  then iterate j  /* ◄═══ passed midnight or  ½  second. */
                end   /*forever*/
   end   /*j*/

halt: say  'program HALTed, it ran for'   format(time("ELapsed"),,2)     'seconds.'
                                                 /*stick a fork in it,  we're all done. */

output

                   1
                   2
                   3
                   4
                   5
                   6
                   7
                   8
                   9
                  10
                  11
                  12
                  13
                  14
                  15
                  16
                  17
                  18
                  19
                  20
                  21
                  22
^C                    ◄■■■■■■■■■■■■■ this where (and when) the user pressed the  Crtl-C  buttons.
program HALTed, it ran for 11.53 seconds.

Note: some REXX interpreters don't show the

^C

when   Ctrl-C   is pressed.

Ruby

t1 = Time.now

catch :done do
  Signal.trap('INT') do
    Signal.trap('INT', 'DEFAULT') # reset to default
    throw :done
  end
  n = 0
  loop do
    sleep(0.5)
    n += 1
    puts n
  end
end

tdelt = Time.now - t1
puts 'Program has run for %5.3f seconds.' % tdelt

Rust

#[cfg(unix)]
fn main() {
    use std::sync::atomic::{AtomicBool, Ordering};
    use std::thread;
    use std::time::{Duration, Instant};

    use libc::{sighandler_t, SIGINT};

    // The time between ticks of our counter.
    let duration = Duration::from_secs(1) / 2;

    // "SIGINT received" global variable.
    static mut GOT_SIGINT: AtomicBool = AtomicBool::new(false);

    unsafe {
        // Initially, "SIGINT received" is false.
        GOT_SIGINT.store(false, Ordering::Release);
        // Interrupt handler that handles the SIGINT signal
        unsafe fn handle_sigint() {
            // It is dangerous to perform any system calls in interrupts, so just set the atomic
            // "SIGINT received" global to true when it arrives.
            GOT_SIGINT.store(true, Ordering::Release);
        }
        // Make handle_sigint the signal handler for SIGINT.
        libc::signal(SIGINT, handle_sigint as sighandler_t);
    }

    // Get the start time...
    let start = Instant::now();

    // Integer counter
    let mut i = 0u32;

    // Every `duration`...
    loop {
        thread::sleep(duration);

        // Break if SIGINT was handled
        if unsafe { GOT_SIGINT.load(Ordering::Acquire) } {
            break;
        }

        // Otherwise, increment and display the integer and continue the loop.
        i += 1;
        println!("{}", i);
    }

    // Get the elapsed time.
    let elapsed = start.elapsed();

    // Print the difference and exit
    println!("Program has run for {} seconds", elapsed.as_secs());
}

#[cfg(not(unix))]
fn main() {
    println!("Not supported on this platform");
}

Scala

Library: Scala

import sun.misc.Signal
import sun.misc.SignalHandler

object SignalHandl extends App {
  val start = System.nanoTime()
  var counter = 0

  Signal.handle(new Signal("INT"), new SignalHandler() {
    def handle(sig: Signal) {
      println(f"\nProgram execution took ${(System.nanoTime() - start) / 1e9f}%f seconds\n")
      exit(0)
    }
  })

  while (true) {
    counter += 1
    println(counter)
    Thread.sleep(500)
  }
}

Sidef

var start = Time.sec

Sig.INT {
    say "Ran for #{Time.sec - start} seconds."
    Sys.exit
}

{ |i|
    say i
    Sys.sleep(0.5)
} * Inf

Output:

1
2
3
4
^CRan for 2 seconds.

Smalltalk

Works with: Smalltalk/X

|n|

n := 0.
UserInterrupt 
     catch:[
         [true] whileTrue:[
             n := n + 1.
             n printCR.
             Delay waitForSeconds: 0.5.
         ]
     ]

or:

[ ... do something... ] on: UserInterrupt do: [:exInfo | ...handler... ]

attaching an OS-signal (unix signal) to an exception or signal instance:

|mySignal|
mySignal := Signal new mayProceed: false.
OperatingSytem operatingSystemSignal: (OperatingSystem signalNamed:'SIGHUP') install: mySignal.
[
   .. do something...
] on: mySignal do:[
   ... handle SIGHUP gracefully...
]

As the runtime system already catches common unix signals and arranges for an OSError to be raised, user code normally does not need to care for this (except for those who want to change that very runtime system behavior ;-).

Swift

Translation of: C

import Foundation

let startTime = NSDate()
var signalReceived: sig_atomic_t = 0

signal(SIGINT) { signal in signalReceived = 1 }

for var i = 0;; {
    if signalReceived == 1 { break }
    usleep(500_000)
    if signalReceived == 1 { break }
    print(++i)
}

let endTime = NSDate()
print("Program has run for \(endTime.timeIntervalSinceDate(startTime)) seconds")

Tcl

Core Tcl does not have signal handling. However the Expect and TclX extension packages do.

Using Expect:

package require Expect

proc sigint_handler {} {
    puts "elapsed time: [expr {[clock seconds] - $::start_time}] seconds"
    set ::looping false
}

trap sigint_handler SIGINT

set start_time [clock seconds]
set n 0
set looping true
while {$looping} {
    puts [incr n]
    after 500
}

Similarly, with TclX:

package require Tclx

proc sigint_handler {} {
    puts "elapsed time: [expr {[clock seconds] - $::start_time}] seconds"
    set ::looping false
}

signal trap sigint sigint_handler

set start_time [clock seconds]
set n 0
set looping true
while {$looping} {
    puts [incr n]
    after 500
}

With TclX, you don't have to trap signals, you can convert the signal into a catchable error:

package require Tclx

signal error sigint 

set start_time [clock seconds]
set n 0
proc infinite_loop {} {
    while 1 { 
        puts [incr n]
        after 500 
    } 
}
if {[catch infinite_loop out] != 0} {
    lassign $::errorCode class name msg
    if {$class eq "POSIX" && $name eq "SIG" && $msg eq "SIGINT"} {
        puts "elapsed time: [expr {[clock seconds] - $start_time}] seconds"
    } else {
        puts "infinite loop interrupted, but not on SIGINT: $::errorInfo"
    }
}

With Tcl 8.6, that would be written as:

package require Tclx

signal error sigint

set start_time [clock seconds]
proc infinite_loop {} {
    while 1 {
        puts [incr n]
        after 500
    }
}
try {
    infinite_loop
} trap {POSIX SIG SIGINT} {} {
    puts "elapsed time: [expr {[clock seconds] - $start_time}] seconds"
}

Note also that from 8.5 onwards, Tcl also has other mechanisms for delivering interrupt-like things, such as interpreter resource limits which permit stopping an execution after a set amount of time and returning control to a supervisor module. However, this is not driven by user interrupts and is so only tangential to this task.

TXR

(set-sig-handler sig-int
                 (lambda (signum async-p)
                   (throwf 'error "caught signal ~s" signum)))

(let ((start-time (time)))
  (catch (each ((num (range 1)))
           (format t "~s\n" num)
           (usleep 500000))
    (error (msg)
           (let ((end-time (time)))
             (format t "\n\n~a after ~s seconds of execution\n"
                     msg (- end-time start-time))))))

Run:

$ txr handle-a-signal.tl
1
2
3
4
5
6
7
8
9
10
11
12
^C

caught signal 2 after 6 seconds of execution

range generates a range of integers as a lazy list, which is infinite if the endpoint argument is omitted. We walk this infinite list using each like any other list.

UNIX Shell

The timing will drift with this example (because we need to consider processing time on top of the wait), but the task demonstrates signal handling. For a more accurate timer, we need to implement a signalling process that signals the shell every half a second.

c="1"
# Trap signals for SIGQUIT (3), SIGABRT (6) and SIGTERM (15)
trap "echo -n 'We ran for ';echo -n `expr $c /2`; echo " seconds"; exit" 3 6 15
while [ "$c" -ne 0 ]; do    # infinite loop
  # wait 0.5    # We need a helper program for the half second interval
  c=`expr $c + 1`
done

Works with: bash

Note that the following solution only works on systems that support a version of sleep that can handle non-integers.

#!/bin/bash
trap 'echo "Run for $((s/2)) seconds"; exit' 2
s=1

while true
do
  echo $s
  sleep .5
  let s++
done

Output:

1
2
3
4
5
^CRun for 2 seconds

Works with: bash

Here is a version of the above which assumes that there is a controlling tty device. It exploits the POSIX standard timeout feature of the tty line discipline. Instead of executing a sleep operation, we execute a terminal read with a 5 tenths of a second timeout:

#!/bin/bash
trap 'echo "Run for $((s/2)) seconds"; exit' 2
s=1

half_sec_sleep()
{
  local save_tty=$(stty -g)
  stty -icanon time 5 min 0
  read
  stty $save_tty
}


while true
do
  echo $s
  half_sec_sleep
  let s++
done

Works with: zsh

TRAPINT(){ print $n; exit }
for (( n = 0; ; n++)) sleep 1

Visual Basic .NET

Translation of: C#

Module Module1
    Dim startTime As Date

    Sub Main()
        startTime = Date.Now
        ' Add event handler for Cntrl+C command
        AddHandler Console.CancelKeyPress, AddressOf Console_CancelKeyPress

        Dim counter = 0
        While True
            counter += 1
            Console.WriteLine(counter)
            Threading.Thread.Sleep(500)
        End While
    End Sub

    Sub Console_CancelKeyPress(sender As Object, e As ConsoleCancelEventArgs)
        Dim stopTime = Date.Now
        Console.WriteLine("This program ran for {0:000.000} seconds", (stopTime - startTime).TotalMilliseconds / 1000)
        Environment.Exit(0)
    End Sub

End Module

Visual FoxPro

*!* In VFP, Ctrl+C is normally used to copy text to the clipboard.
*!* Esc is used to stop execution.
CLEAR
SET ESCAPE ON
ON ESCAPE DO StopLoop
CLEAR DLLS
DECLARE Sleep IN WIN32API INTEGER nMilliSeconds
lLoop = .T.
n = 0
? "Press Esc to Cancel..."
t1 = INT(SECONDS())
DO WHILE lLoop
	n = n + 1 
	? n
	Sleep(500)
ENDDO	
? "Elapsed time:", TRANSFORM(INT(SECONDS()) - t1) + " secs."
CLEAR DLLS
RETURN TO MASTER

PROCEDURE StopLoop
lLoop = .F.
ENDPROC

Wren

Note that Thread.sleep not only suspends the current fiber but also the System.clock method (possibly unintended). We therefore have to add back on the time slept.

import "scheduler" for Scheduler
import "timer" for Timer
import "io" for Stdin

var start = System.clock
var stop = false

Scheduler.add {
    var n = 0
    while (true) {
        System.print(n)
        if (stop) {
            var elapsed = System.clock - start + n * 0.5
            System.print("Program has run for %(elapsed) seconds.")
            return
        }
        Timer.sleep(500)
        n = n + 1
    }
}

Stdin.isRaw = true  // enable control characters to go into stdin
while (true) {
    var b = Stdin.readByte()
    if (b == 3 || b == 28) break  // quits on pressing either Ctrl-C os Ctrl-\
}
Stdin.isRaw = false
stop = true

Output:

Sample run:

0
1
2
3
4
5
6
7
8
9
10
11
12
Program has run for 6.00173 seconds.

X86 Assembly

Works with: NASM version Linux

Now, I realize linking to C libraries is somewhat cheating. It is entirely possible to do this entirely in syscalls using sys_nanosleep/sys_write but that would require allot more work, definition of the timespec structure among other things.

%define sys_signal 	48
%define SIGINT			2
%define sys_time	13

extern usleep
extern printf

section .text
	global _start
	
	_sig_handler:
		mov ebx, end_time
		mov eax, sys_time
		int 0x80
		mov eax, dword [start_time]
		mov ebx, dword [end_time]
		sub ebx, eax
		mov ax, 100
		div ebx
		push ebx
		push p_time
		call printf
		push 0x1
		mov eax, 1
		push eax
		int 0x80
		ret
		
	_start:
		mov ebx, start_time
		mov eax, sys_time
		int 0x80
		mov ecx, _sig_handler
		mov ebx, SIGINT
		mov eax, sys_signal
		int 0x80
		xor edi, edi
		.looper:
			push 500000
			call usleep
			push edi
			push p_cnt
			call printf
			inc edi
		jmp .looper
		
section .data
p_time	db "The program has run for %d seconds.",13,10,0
p_cnt		db "%d",13,10,0

section .bss
start_time	resd 1
end_time		resd 1

zkl

SigInt is the only signal zkl brings out.

var t=Time.Clock.time;
try{ n:=0; while(1){(n+=1).println(); Atomic.sleep(0.5)} }
catch{ println("ran for ",Time.Clock.time-t," seconds"); System.exit() }

Output:

1
2
3
4
5
6
^C
ran for 2 seconds