In windows, you can create Mutex. That's how I ensure no other instance of the same program is running.
YourIDString is a string that you use to uniquely id your program instance .
if OpenMutex(MUTEX_ALL_ACCESS, False, PChar(YourIDString)) = 0 then begin
// First one - the mutex didn't exist, so create it.
Result := CreateMutex(nil, False, PChar(YourIDString));
MutexList.Add(pointer(Result));
end else begin
raise Exception.Create('The same program has been running already');
end;
Make sure your free all mutex in the finalization of your unit or program
procedure FreeAllMutexes;
var
M : THandle;
i : integer;
begin
for i := 0 to MutexList.Count - 1 do begin
M := THandle(MutexList[i]);
if M 0 then begin
if not CloseHandle(M) then
raise Exception.Create('Failed to release mutex:' + IntToStr(M));
MutexList[i] := nil;
end;
end;
end;
Mark Morgan Lloyd wrote 26 lines
Graeme Geldenhuys wrote:
> On 2013-04-04 10:45, Mark Morgan Lloyd wrote:
>> So far I've had no success porting that to Windows using named pipes,
>
> Ah, thanks for the idea. SimpleIPC should be able to do the trick -
> similar to how apps communicate to a DebugServer (using dbugintf and
> SimpleIPC units).
>
> First instance will search for a known IPC server, if none exist, start
> the Simple IPC server. Second instance will first see if a existing IPC
> server exists, and if so, send the open command to it, then quit.
Yes, I agree. But my preference is to put the socket/pipe in the
user's home directory (i.e. rather than /tmp which is where it's
usually put), to name it including the PID to make it easily
trackable, and to use some combination of the original project name,
the final executable name (and possibly something from a .ini file) so
that it's possible to handle multiple instances.
I suggest also adding status commands etc., i.e. so that you can query
whether a server's running, what its build is and so on. The way I did
it wasn't very good for that: it really needs bidirectional
communications (e.g. so that you can get the running copy's version
rather than just a version number from the binary you've just
executed) which isn't something I designed in.
