Simpler mdb_node_shrink()

libraries/liblmdb/mdb.c

@@ -7183,45 +7183,38 @@ 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_pad;
+		len = nsize;
 		if (nsize & 1)
 			return;		/* do not make the node uneven-sized */
-		memmove(METADATA(xp), METADATA(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_pad = sp->mp_pad;
-	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;
 }