Re: PROC struct - Mailing list pgsql-bugs

From Tom Lane
Subject Re: PROC struct
Date
Msg-id 16710.981391012@sss.pgh.pa.us
Whole thread Raw
In response to PROC struct  (Myron Scott <mscott@sacadia.com>)
Responses Re: PROC struct  (Myron Scott <mscott@sacadia.com>)
List pgsql-bugs
Myron Scott <mscott@sacadia.com> writes:
> May I suggest that watiHolder and waitLock pointers
> in the proc struct in proc.h be changed from direct
> pointers to SHMEM_OFFSET.  They are both shared memory
> structures in a shared memory structure and it would
> be more consistent to make these SHMEM_OFFSET.  Direct
> pointers will be a problem if another process which is
> not the result of a fork tries to attach to the shared memory.

I don't really foresee that that's an issue --- any process
we might conceivably want to have reading the shmem would be
spawned by the postmaster anyway.  I've actually been thinking
about ripping out the shmem-offset-to-pointer-and-back conversions
on the grounds of code simplification, readability, reliability
(the compiler cannot detect whether you are casting a reconverted
SHMEM_OFFSET to the wrong pointer type), and speed.

            regards, tom lane

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