pgsql: Management of free memory pages.

Management of free memory pages.

This is intended as infrastructure for a full-fledged allocator for
dynamic shared memory.  The interface looks a bit like a real
allocator, but only supports allocating and freeing memory in
multiples of the 4kB page size.  Further, to free memory, you must
know the size of the span you wish to free, in pages.  While these are
make it unsuitable as an allocator in and of itself, it still serves
as very useful scaffolding for a full-fledged allocator.

Robert Haas and Thomas Munro.  This code is mostly the same as my 2014
submission, but Thomas fixed quite a few bugs and made some changes to
the interface.

Discussion: CA+TgmobkeWptGwiNa+SGFWsTLzTzD-CeLz0KcE-y6LFgoUus4A@mail.gmail.com
Discussion: CAEepm=1z5WLuNoJ80PaCvz6EtG9dN0j-KuHcHtU6QEfcPP5-qA@mail.gmail.com

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/13e14a78ea15f4c581cae408b5010c13961c96de

Modified Files
--------------
src/backend/utils/mmgr/Makefile   |    2 +-
src/backend/utils/mmgr/freepage.c | 1886 +++++++++++++++++++++++++++++++++++++
src/include/utils/freepage.h      |   99 ++
src/tools/pgindent/typedefs.list  |    7 +
4 files changed, 1993 insertions(+), 1 deletion(-)