Change me_nodemax to not count the mp_ptrs[] entry. That's mostly
how it was used. Compare node sizes ">" me_nodemax instead of ">=".
The ">=" was a workaround for confusing sizes with and without the
mp_ptrs[] entry, but broke for nodes with size (old me_nodemax-1).
Explicitly make me_nodemax even. An odd value could break the
comparisons. It was even anyway because MDB_MINKEYS == 2.
Use DB page size = min(32k, OS pagesize). Previous limit was 8k
(MDB_MINKEYS*MDB_PAGESIZE).
Handle DB pagesize < OS pagesize. That's an I/O pessimization,
but transactions remain atomic: Only writing the MDB_meta must
be atomic, and it fits in one OS page.
Don't truncate desired subpage size: Asssign it to a size_t
(mv_size), not an uint16_t (mp_upper).
Both were unused and md_name was unmaintained -- except
mdb_cursor_touch(xcursor) would abuse md_name as a key to
touch MAIN_DBI if it could somehow get passed ! DB_DIRTY.
xcursor DBIs were parent DBI+1 for debugging. Instead output
-(parent DBI). Fixes a crash in mdb_cursor_del0()'s xcursor
tracking, it forgot to subtract 1 for C_SUB cursors.
MDB_txn.mt_toggle: Use (mt_txnid & 1) instead.
Drop error checks which will be repeated.
mdb_cursor_set(): Turn assert into if/return to match the above.
mdb_cursor_del(): 'flags' are now used as bitflags.
Only named DBs can have DB_STALE, and they do not use MDB_PS_MODIFY.
Replace magic key values with flags. Drop duplicated comments at
mdb_page_search_root() vs. mdb_page_search(), and rephrase.
Catch malloc error.
Fix hunt for dirty vs spilled pages: Don't leave x at a deleted pageno.
Cleanup: Factor out variables, squash pages already marked for deletion.
Fix description & code: Also ignore dirty pages hidden by
spilled pages, as they won't merge into our dirty_list.
Update it in mdb_page_flush() instead of mdb_page_spill().
Hallvard Furuseth