RE: NSProcessInfo globallyUniqueString

[Roland Schwingel]

Hi...

(I couldn't find David Ayers patch in my gnustep mailinglist mails so I decided
to also post my solution - I only had the mail of Richard Frith-Macdonald 
forwarded below)

I faced the very same problems a while ago also. I use
this method very frequently for temporary filenames etc.

So to be unique again (and to avoid the : problem - which 
awfully breaks on windows) I placed a category to that
method doing this a long time ago:

{
        //        static time_t                 startTime = 0;
        static NSString        *hostName = nil;
        static long                        counter = 1;
        static pid_t                 pid = 0;
        
        if (!hostName)
        {
                hostName = [[NSProcessInfo processInfo] hostName];
                
                if (![hostName length])
                        hostName = @"localhost";
                else
                {
                        NSArray *components = [hostName componentsSeparatedByString:@"."];
                        
                        hostName = [[components objectAtIndex:0] retain];
                }
                        
                #ifdef __MINGW__
                pid = GetCurrentProcessId();
                #else
                pid = getpid();
                #endif
                
                // startTime = time(NULL);
        }
        
        //        return [NSString stringWithFormat:@"tmp-%@-%x-%x-%x",hostName,pid,time(NULL)-startTime,counter++];
        return [NSString stringWithFormat:@"tmp-%@-%x-%x",hostName,pid,counter++];
}

I decided that a timestamp is not really necessary when you have a counter which is incremented on every call, so I
omitted that (but still available commented out). OS4.2 is also always adding a counter to the string.

This version now runs for over a year for me perfectly on windows and unix...

Roland

======================================

FROM: Richard Frith-Macdonald
DATE: 08/07/2002 09:16:53
SUBJECT: RE:  NSProcessInfo globallyUniqueString

On Monday, July 22, 2002, at 01:41 PM, David Ayers wrote:

> Hallo all,
>
> on my maching the globallyUniqueString produced by NSProcessInfo wasn't
> always globally unique since the precision of the date output only
> evaluated
> to seconds.

Thanks ... your fix didn't absolutely guarantee uniqueness, so I added a
lock
protected counter too.

> Also some of apps I know use this string to create filenames and
> the usage of ':' causes problems. Therefor I propose the following
> patch.
> Yet if some apps already rely on the date format, I've included another
> alternative. But I believe, relying on the format of this string is a
> bug.

I think relying on it to form a legal filename might be considered a bug
as well,
but the current implementation should be ok on unix style machines at
least.