Re: Question about SHM_QUEUE

ITAGAKI Takahiro <itagaki.takahiro@oss.ntt.co.jp> writes:
> I have a question about SHM_QUEUE. Why do we need this component?

It's a hangover from Berkeley days that no one has felt a need to remove
yet.  The convention back then was that shared memory might be mapped to
different addresses in different processes.  We've since adopted the
assumption that everyone will see the same addresses, but we have not
made any attempt to eradicate the old approach everywhere.

> Then, can we replace SHM_QUEUE by a pointer-based double-linked list?
> It will be an "intrusive" version of Dllist.

What exactly will you gain by it?  I'm not inclined to fool with that
code for trivial reasons ...
        regards, tom lane