Reserve zero as an invalid DSM handle.
Previously, the handle for the control segment could not be zero, but
some other DSM segment could potentially have a handle value of zero.
However, that means that if someone wanted to store a dsm_handle that
might or might not be valid, they would need a separate boolean to
keep track of whether the associated value is legal. That's annoying,
so change things so that no DSM segment can ever have a handle of 0 -
or as we call it here, DSM_HANDLE_INVALID.
Thomas Munro. This was submitted as part of a much larger patch to
add an malloc-like allocator for dynamic shared memory, but this part
seems like a good idea independently of the rest of the patch.
Branch
------
master
Details
-------
http://git.postgresql.org/pg/commitdiff/b40b4dd9e10ea701c8d47ccba9407fc32ed384e5
Modified Files
--------------
src/backend/storage/ipc/dsm.c | 4 +++-
src/include/storage/dsm.h | 3 +++
2 files changed, 6 insertions(+), 1 deletion(-)
