(ITS#9027) LMDB: API to retrieve map address

Full_Name: Nic Watson Version: OS: Linux URL: ftp://ftp.openldap.org/incoming/ Submission from: (NULL) (73.132.68.128)

Goal: I'd like a clean way to get at the address of the data memory map in LMDB.

MDB_envinfo.me_mapaddr only returns the map address if MAP_FIXED is used.

Current Workarounds: * Use OS-specific mechanism to retrieve all memory maps (e.g. /proc/<pid>/smaps). * Defeat opaque handle and reach into the MDB_env struct directly and grab the me_map field.

Justification: In my current application, I notice a significant performance increase if I mlock the mapfile. In order to do that cleanly, I need the address of the map.