Re: [ros-diffs] [ion] 14711: Remove bogus error message. It is normal for Mutex creation to fail since the Object will alredy exist after the first time it's created

[Joseph Galbraith]

Thomas Weidenmueller wrote:
>   Joseph Galbraith wrote:
> >   If CreateMutex() returns NULL, it failed for
> > some
> >  other reason (than that the mutex already existed,
> >  since CreateMutex doesn't fail in this case.) 
>  
>  Quote from the PSDK: "If lpName matches the name of an existing event, 
>  semaphore, waitable timer, job, or file-mapping object, the function 
>  fails and the GetLastError function returns ERROR_INVALID_HANDLE. This 
>  occurs because these objects share the same name space." 
Ahh... I see the confusion;  I'll counter with another quote
from the platform SDK:

   Return Values

   If the function succeeds, the return value is a handle
   to the mutex object. If the named mutex object existed
   before the function call, the function returns a handle
   to the existing object and GetLastError returns
   ERROR_ALREADY_EXISTS. Otherwise, the caller created the mutex.

   If the function fails, the return value is NULL. To get
   extended error information, call GetLastError.

If you read your quote carefully, you'll notice that it is
refering to existing events, semaphores, waitable timers, jobs,
or file-mapping objets... mutex is notably absent from the list.
The key is the last sentance:  "This occurs because these objects
[the ones listed] share the same name space [as mutex objects.]

I do see now where the confusion comes from though; at first I was
just going to respond that the two pieces of platform SDK documentation
were in conflict, and the one I quoted is the behavior observed
experimentally... then I read carefully.

Thanks,

Joseph