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From Amit Athavale <amit_athav...@persistent.co.in>
Subject Re: apr_shm_attach() and APR_EEXIST
Date Fri, 28 May 2004 07:01:37 GMT

Joe Orton wrote:

>>I don't think it is possible. APR does not pass back any information
>>in case of error, other than error code itself. (and anyway XXX is shmid
>>returned by shmget() which is failing in your case)
>I guess it could be made useful either by having apr_shm_create() remove
>an existing shm segment with the given name then re-create it (as MM
>does IIRC), 
MM takes care for this for mmap style shared-memory. Talking about shm_xxx
style shared-memory, AFAIU it simply keeps itself away from name-based shm.

>or to add an apr_shm_remove() function which removes a
>name-based shm segment as only APR knows how.
+1 on this idea.

It would be very useful for programmers. They could simply do one of the
following to avoid headaches of admins :)

- call apr_shm_remove right before apr_shm_create()
- detect unclean shutdown case and call apr_shm_remove()

I could prepare a patch for this if people are happy with this idea ;)

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