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lmdb: Simpler mdb_node_shrink().

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Change-Id: If0e4153e69c4f858ee45471c4888ec2024253b50
This commit is contained in:
Hallvard Furuseth
2015-07-04 13:48:05 +02:00
committed by Leo Yuriev
parent a6fa632a54
commit 6524dbf3a1
1 changed files with 15 additions and 22 deletions
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37
mdb.c
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@@ -7012,45 +7012,38 @@ mdb_node_shrink(MDB_page *mp, indx_t indx)
MDB_node *node;
MDB_page *sp, *xp;
char *base;
int nsize, delta;
indx_t i, numkeys, ptr;
indx_t delta, nsize, len, ptr;
int i;
node = NODEPTR(mp, indx);
sp = (MDB_page *)NODEDATA(node);
delta = SIZELEFT(sp);
xp = (MDB_page *)((char *)sp + delta);
nsize = NODEDSZ(node) - delta;
/* shift subpage upward */
/* Prepare to shift upward, set len = length(subpage part to shift) */
if (IS_LEAF2(sp)) {
nsize = NUMKEYS(sp) * sp->mp_ksize;
len = nsize;
if (nsize & 1)
return; /* do not make the node uneven-sized */
memmove(PAGEDATA(xp), PAGEDATA(sp), nsize);
} else {
int i;
numkeys = NUMKEYS(sp);
for (i=numkeys-1; i>=0; i--)
xp = (MDB_page *)((char *)sp + delta); /* destination subpage */
for (i = NUMKEYS(sp); --i >= 0; )
xp->mp_ptrs[i] = sp->mp_ptrs[i] - delta;
len = PAGEHDRSZ;
}
xp->mp_upper = sp->mp_lower;
xp->mp_lower = sp->mp_lower;
xp->mp_flags = sp->mp_flags;
xp->mp_ksize = sp->mp_ksize;
COPY_PGNO(xp->mp_pgno, mp->mp_pgno);
nsize = NODEDSZ(node) - delta;
sp->mp_upper = sp->mp_lower;
COPY_PGNO(sp->mp_pgno, mp->mp_pgno);
SETDSZ(node, nsize);
/* shift lower nodes upward */
/* Shift <lower nodes...initial part of subpage> upward */
base = (char *)mp + mp->mp_upper + PAGEBASE;
memmove(base + delta, base, (char *)sp + len - base);
ptr = mp->mp_ptrs[indx];
numkeys = NUMKEYS(mp);
for (i = 0; i < numkeys; i++) {
for (i = NUMKEYS(mp); --i >= 0; ) {
if (mp->mp_ptrs[i] <= ptr)
mp->mp_ptrs[i] += delta;
}
base = (char *)mp + mp->mp_upper + PAGEBASE;
memmove(base + delta, base, ptr - mp->mp_upper + NODESIZE + NODEKSZ(node));
mp->mp_upper += delta;
}