MDB_env.me_pghead: Don't free it when empty. mdb_ovpage_free()
needs it, but cannot allocate it.
mdb_midl_alloc(): Fill in length=0.
mdb_page_alloc(): Also Skip freeDB if txnid<3, instead of <4,
and consistently DPRINTF consumed IDLs.
When copying, round up/down to aligned sizes. Skip the unused portion,
this was not done when touching a page dirty in the parent txn.
No other change in behavior.
Simplify mdb_page_touch(), including: Drop test m3==mc, the condition
is caught below. Don't "modify" the parent's pgno into the same pgno,
when a nested txn copies a parent's page into its freelist.
The tracking code should not change the current cursor.
It did when that was a C_SUB cursor, which should not be
checked against the tracked cursors but their xcursors.
However, do not bother to skip the tracking code for the
current cursor when it would not change that cursor anyway.
Do not binary-search dirty_list, it is unsorted when MDB_WRITEMAP.
Catch errors. In nested txns, put the page in mt_free_pgs after
all since pages dirty in a parent txn would add complexities.
Split up saving me_pghead, to make me_pgfree unneeded. Also mf_pghead
is now a midl. Needed after e7f6767ea8
("Return fresh overflow pages to current pghead").
Tweak MDB_DEBUG freelist output, make it ascending.
Do not rescan reader table (mdb_find_oldest) after "goto again".
Skip clearing dirty_list[nonzero].mid in mdb_dlist_free(); it
was not done in mdb_reset0() anyway.
MDB_NEXT_NODUP, MDB_PREV_NODUP: Allow for non-MDB_DUPSORT databases.
No mdb.c code changes needed.
mdb_stat.c: Use MDB_NEXT_NODUP, to avoid a crash with a DUPSORT mainDB.
Reject attempts to open named databases if the main
database has flag MDB_DUPSORT or MDB_INTEGERKEY.
DUPSORT would require an xcursor for the DB, INTEGERKEY
would expect the DB name to be a binary integer.
mdb_page_malloc(): Add "number of pages" parameter.
mdb_page_get(): Add output param for how page was found.
Do not set return params on error.
mdb_cursor_put(): Catch mdb_page_get() error.
Prepares for next commit, no change in caller behavior other
than on mdb_page_get error.
No real change.
mdb_cursor_init() checks if it needs mx, so pass it unconditionally.
Set C_ALLOCD for shadow cursors, for clarity. (It was always set as
it should anyway from the origin cursor, which would have C_ALLOCD.)
Close remaining cursors when committing a write txn. The doc says this
happens, and it avoids cursor tracking when updating mainDB + freeDB.
Rename mdb_cursor_merge() -> mdb_cursors_close() for code reuse,
and add a merge option. Simplify its loop a bit.
Factor out cleanup of DBIs.
Hallvard Furuseth