C++ NEXTINDEX函数代码示例

/*
 * BT_RROOT -- Fix up the recno root page after it has been split.
 *
 * Parameters:
 *	t:	tree
 *	h:	root page
 *	l:	left page
 *	r:	right page
 *
 * Returns:
 *	RET_ERROR, RET_SUCCESS
 */
static int
bt_rroot(BTREE *t, PAGE *h, PAGE *l, PAGE *r)
{
	char *dest;

	/* Insert the left and right keys, set the header information. */
	h->linp[0] = h->upper = t->bt_psize - NRINTERNAL;
	dest = (char *)h + h->upper;
	WR_RINTERNAL(dest,
	    l->flags & P_RLEAF ? NEXTINDEX(l) : rec_total(l), l->pgno);

	__PAST_END(h->linp, 1) = h->upper -= NRINTERNAL;
	dest = (char *)h + h->upper;
	WR_RINTERNAL(dest,
	    r->flags & P_RLEAF ? NEXTINDEX(r) : rec_total(r), r->pgno);

	h->lower = BTDATAOFF + 2 * sizeof(indx_t);

	/* Unpin the root page, set to recno internal page. */
	h->flags &= ~P_TYPE;
	h->flags |= P_RINTERNAL;
	mpool_put(t->bt_mp, h, MPOOL_DIRTY);

	return (RET_SUCCESS);
}

void
unlinkpg(DB *dbp)
{
	BTREE *t = dbp->internal;
	PAGE *h = NULL;
	pgno_t pg;

	for (pg = P_ROOT; pg < t->bt_mp->npages;
	     mpool_put(t->bt_mp, h, 0), pg++) {
		if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
			break;
		/* Look for a nonempty leaf page that has both left
		 * and right siblings. */
		if (h->prevpg == P_INVALID || h->nextpg == P_INVALID)
			continue;
		if (NEXTINDEX(h) == 0)
			continue;
		if ((h->flags & (P_BLEAF | P_RLEAF)))
			break;
	}
	if (h == NULL || pg == t->bt_mp->npages) {
		errx(1, "%s: no appropriate page found", __func__);
		return;
	}
	if (__bt_relink(t, h) != 0) {
		perror("unlinkpg");
		goto cleanup;
	}
	h->prevpg = P_INVALID;
	h->nextpg = P_INVALID;
cleanup:
	mpool_put(t->bt_mp, h, MPOOL_DIRTY);
}

/*
 * REC_TOTAL -- Return the number of recno entries below a page.
 *
 * Parameters:
 *	h:	page
 *
 * Returns:
 *	The number of recno entries below a page.
 *
 * XXX
 * These values could be set by the bt_psplit routine.  The problem is that the
 * entry has to be popped off of the stack etc. or the values have to be passed
 * all the way back to bt_split/bt_rroot and it's not very clean.
 */
static recno_t
rec_total(PAGE *h)
{
	recno_t recs;
	indx_t nxt, top;

	for (recs = 0, nxt = 0, top = NEXTINDEX(h); nxt < top; ++nxt)
		recs += GETRINTERNAL(h, nxt)->nrecs;
	return (recs);
}

/*
 * __bt_dleaf --
 *	Delete a single record from a leaf page.
 *
 * Parameters:
 *	t:	tree
 *    key:	referenced key
 *	h:	page
 *	idx:	index on page to delete
 *
 * Returns:
 *	RET_SUCCESS, RET_ERROR.
 */
int
__bt_dleaf(BTREE *t, const DBT *key, PAGE *h, u_int idx)
{
	BLEAF *bl;
	indx_t cnt, *ip, offset;
	u_int32_t nbytes;
	void *to;
	char *from;

	/* If this record is referenced by the cursor, delete the cursor. */
	if (F_ISSET(&t->bt_cursor, CURS_INIT) &&
	    !F_ISSET(&t->bt_cursor, CURS_ACQUIRE) &&
	    t->bt_cursor.pg.pgno == h->pgno && t->bt_cursor.pg.index == idx &&
	    __bt_curdel(t, key, h, idx))
		return (RET_ERROR);

	/* If the entry uses overflow pages, make them available for reuse. */
	to = bl = GETBLEAF(h, idx);
	if (bl->flags & P_BIGKEY && __ovfl_delete(t, bl->bytes) == RET_ERROR)
		return (RET_ERROR);
	if (bl->flags & P_BIGDATA &&
	    __ovfl_delete(t, bl->bytes + bl->ksize) == RET_ERROR)
		return (RET_ERROR);

	/* Pack the remaining key/data items at the end of the page. */
	nbytes = NBLEAF(bl);
	from = (char *)h + h->upper;
	memmove(from + nbytes, from, (char *)to - from);
	h->upper += nbytes;

	/* Adjust the indices' offsets, shift the indices down. */
	offset = h->linp[idx];
	for (cnt = idx, ip = &h->linp[0]; cnt--; ++ip)
		if (ip[0] < offset)
			ip[0] += nbytes;
	for (cnt = NEXTINDEX(h) - idx; --cnt; ++ip)
		ip[0] = ip[1] < offset ? ip[1] + nbytes : ip[1];
	h->lower -= sizeof(indx_t);

	/* If the cursor is on this page, adjust it as necessary. */
	if (F_ISSET(&t->bt_cursor, CURS_INIT) &&
	    !F_ISSET(&t->bt_cursor, CURS_ACQUIRE) &&
	    t->bt_cursor.pg.pgno == h->pgno && t->bt_cursor.pg.index > idx)
		--t->bt_cursor.pg.index;

	return (RET_SUCCESS);
}

/*
 * __REC_DLEAF -- Delete a single record from a recno leaf page.
 *
 * Parameters:
 *	t:	tree
 *	idx:	index on current page to delete
 *
 * Returns:
 *	RET_SUCCESS, RET_ERROR.
 */
int
__rec_dleaf(BTREE *t, PAGE *h, u_int32_t idx)
{
	RLEAF *rl;
	indx_t *ip, cnt, offset;
	u_int32_t nbytes;
	char *from;
	void *to;

	/*
	 * Delete a record from a recno leaf page.  Internal records are never
	 * deleted from internal pages, regardless of the records that caused
	 * them to be added being deleted.  Pages made empty by deletion are
	 * not reclaimed.  They are, however, made available for reuse.
	 *
	 * Pack the remaining entries at the end of the page, shift the indices
	 * down, overwriting the deleted record and its index.  If the record
	 * uses overflow pages, make them available for reuse.
	 */
	to = rl = GETRLEAF(h, idx);
	if (rl->flags & P_BIGDATA && __ovfl_delete(t, rl->bytes) == RET_ERROR)
		return (RET_ERROR);
	nbytes = NRLEAF(rl);

	/*
	 * Compress the key/data pairs.  Compress and adjust the [BR]LEAF
	 * offsets.  Reset the headers.
	 */
	from = (char *)h + h->upper;
	memmove(from + nbytes, from, (char *)to - from);
	h->upper += nbytes;

	offset = h->linp[idx];
	for (cnt = &h->linp[idx] - (ip = &h->linp[0]); cnt--; ++ip)
		if (ip[0] < offset)
			ip[0] += nbytes;
	for (cnt = &h->linp[NEXTINDEX(h)] - ip; --cnt; ++ip)
		ip[0] = ip[1] < offset ? ip[1] + nbytes : ip[1];
	h->lower -= sizeof(indx_t);
	--t->bt_nrecs;
	return (RET_SUCCESS);
}

/*
 * __bt_sprev --
 *	Check for an exact match before the key.
 *
 * Parameters:
 *	t:	tree
 *	h:	current page
 *	key:	key
 *	exactp:	pointer to exact match flag
 *
 * Returns:
 *	If an exact match found.
 */
static int
__bt_sprev(BTREE *t, PAGE *h, const DBT *key, int *exactp)
{
	EPG e;

	/*
	 * Get the previous page.  The key is either an exact
	 * match, or not as good as the one we already have.
	 */
	if ((e.page = mpool_get(t->bt_mp, h->prevpg, 0)) == NULL)
		return (0);
	e.index = NEXTINDEX(e.page) - 1;
	if (__bt_cmp(t, key, &e) == 0) {
		mpool_put(t->bt_mp, h, 0);
		t->bt_cur = e;
		*exactp = 1;
		return (1);
	}
	mpool_put(t->bt_mp, e.page, 0);
	return (0);
}

/*
 * __bt_seqset --
 *	Set the sequential scan to a specific key.
 *
 * Parameters:
 *	t:	tree
 *	ep:	storage for returned key
 *	key:	key for initial scan position
 *	flags:	R_CURSOR, R_FIRST, R_LAST, R_NEXT, R_PREV
 *
 * Side effects:
 *	Pins the page the cursor references.
 *
 * Returns:
 *	RET_ERROR, RET_SUCCESS or RET_SPECIAL if there's no next key.
 */
static int
__bt_seqset(BTREE *t, EPG *ep, DBT *key, int flags)
{
	PAGE *h;
	pgno_t pg;
	int exact;

	/*
	 * Find the first, last or specific key in the tree and point the
	 * cursor at it.  The cursor may not be moved until a new key has
	 * been found.
	 */
	switch (flags) {
	case R_CURSOR:				/* Keyed scan. */
		/*
		 * Find the first instance of the key or the smallest key
		 * which is greater than or equal to the specified key.
		 */
		if (key->data == NULL || key->size == 0) {
			errno = EINVAL;
			return (RET_ERROR);
		}
		return (__bt_first(t, key, ep, &exact));
	case R_FIRST:				/* First record. */
	case R_NEXT:
		/* Walk down the left-hand side of the tree. */
		for (pg = P_ROOT;;) {
			if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
				return (RET_ERROR);

			/* Check for an empty tree. */
			if (NEXTINDEX(h) == 0) {
				mpool_put(t->bt_mp, h, 0);
				return (RET_SPECIAL);
			}

			if (h->flags & (P_BLEAF | P_RLEAF))
				break;
			pg = GETBINTERNAL(h, 0)->pgno;
			mpool_put(t->bt_mp, h, 0);
		}
		ep->page = h;
		ep->index = 0;
		break;
	case R_LAST:				/* Last record. */
	case R_PREV:
		/* Walk down the right-hand side of the tree. */
		for (pg = P_ROOT;;) {
			if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
				return (RET_ERROR);

			/* Check for an empty tree. */
			if (NEXTINDEX(h) == 0) {
				mpool_put(t->bt_mp, h, 0);
				return (RET_SPECIAL);
			}

			if (h->flags & (P_BLEAF | P_RLEAF))
				break;
			pg = GETBINTERNAL(h, NEXTINDEX(h) - 1)->pgno;
			mpool_put(t->bt_mp, h, 0);
		}

		ep->page = h;
		ep->index = NEXTINDEX(h) - 1;
		break;
	}
	return (RET_SUCCESS);
}

/*
 * __bt_delete
 *	Delete the item(s) referenced by a key.
 *
 * Return RET_SPECIAL if the key is not found.
 */
int
__bt_delete(const DB *dbp, const DBT *key, u_int flags)
{
	BTREE *t;
	CURSOR *c;
	PAGE *h;
	int status;

	t = dbp->internal;

	/* Toss any page pinned across calls. */
	if (t->bt_pinned != NULL) {
		mpool_put(t->bt_mp, t->bt_pinned, 0);
		t->bt_pinned = NULL;
	}

	/* Check for change to a read-only tree. */
	if (F_ISSET(t, B_RDONLY)) {
		errno = EPERM;
		return (RET_ERROR);
	}

	switch (flags) {
	case 0:
		status = __bt_bdelete(t, key);
		break;
	case R_CURSOR:
		/*
		 * If flags is R_CURSOR, delete the cursor.  Must already
		 * have started a scan and not have already deleted it.
		 */
		c = &t->bt_cursor;
		if (F_ISSET(c, CURS_INIT)) {
			if (F_ISSET(c, CURS_ACQUIRE | CURS_AFTER | CURS_BEFORE))
				return (RET_SPECIAL);
			if ((h = mpool_get(t->bt_mp, c->pg.pgno, 0)) == NULL)
				return (RET_ERROR);

			/*
			 * If the page is about to be emptied, we'll need to
			 * delete it, which means we have to acquire a stack.
			 */
			if (NEXTINDEX(h) == 1)
				if (__bt_stkacq(t, &h, &t->bt_cursor))
					return (RET_ERROR);

			status = __bt_dleaf(t, NULL, h, c->pg.index);

			if (NEXTINDEX(h) == 0 && status == RET_SUCCESS) {
				if (__bt_pdelete(t, h))
					return (RET_ERROR);
			} else
				mpool_put(t->bt_mp,
				    h, status == RET_SUCCESS ? MPOOL_DIRTY : 0);
			break;
		}
		/* FALLTHROUGH */
	default:
		errno = EINVAL;
		return (RET_ERROR);
	}
	if (status == RET_SUCCESS)
		F_SET(t, B_MODIFIED);
	return (status);
}

/*
 * BT_DPAGE -- Dump the page
 *
 * Parameters:
 *	h:	pointer to the PAGE
 */
void
__bt_dpage(PAGE *h)
{
	BINTERNAL *bi;
	BLEAF *bl;
	RINTERNAL *ri;
	RLEAF *rl;
	indx_t cur, top;
	char *sep;

	(void)fprintf(stderr, "    page %u: (", h->pgno);
#undef X
#define	X(flag, name) \
	if (h->flags & flag) { \
		(void)fprintf(stderr, "%s%s", sep, name); \
		sep = ", "; \
	}
	sep = "";
	X(P_BINTERNAL,	"BINTERNAL")		/* types */
	X(P_BLEAF,	"BLEAF")
	X(P_RINTERNAL,	"RINTERNAL")		/* types */
	X(P_RLEAF,	"RLEAF")
	X(P_OVERFLOW,	"OVERFLOW")
	X(P_PRESERVE,	"PRESERVE");
	(void)fprintf(stderr, ")\n");
#undef X

	(void)fprintf(stderr, "\tprev %2u next %2u", h->prevpg, h->nextpg);
	if (h->flags & P_OVERFLOW)
		return;

	top = NEXTINDEX(h);
	(void)fprintf(stderr, " lower %3d upper %3d nextind %d\n",
	    h->lower, h->upper, top);
	for (cur = 0; cur < top; cur++) {
		(void)fprintf(stderr, "\t[%03d] %4d ", cur, h->linp[cur]);
		switch (h->flags & P_TYPE) {
		case P_BINTERNAL:
			bi = GETBINTERNAL(h, cur);
			(void)fprintf(stderr,
			    "size %03d pgno %03d", bi->ksize, bi->pgno);
			if (bi->flags & P_BIGKEY)
				(void)fprintf(stderr, " (indirect)");
			else if (bi->ksize)
				(void)fprintf(stderr,
				    " {%.*s}", (int)bi->ksize, bi->bytes);
			break;
		case P_RINTERNAL:
			ri = GETRINTERNAL(h, cur);
			(void)fprintf(stderr, "entries %03d pgno %03d",
				ri->nrecs, ri->pgno);
			break;
		case P_BLEAF:
			bl = GETBLEAF(h, cur);
			if (bl->flags & P_BIGKEY)
				(void)fprintf(stderr,
				    "big key page %u size %u/",
				    *(pgno_t *)bl->bytes,
				    *(u_int32_t *)(bl->bytes + sizeof(pgno_t)));
			else if (bl->ksize)
				(void)fprintf(stderr, "%s/", bl->bytes);
			if (bl->flags & P_BIGDATA)
				(void)fprintf(stderr,
				    "big data page %u size %u",
				    *(pgno_t *)(bl->bytes + bl->ksize),
				    *(u_int32_t *)(bl->bytes + bl->ksize +
				    sizeof(pgno_t)));
			else if (bl->dsize)
				(void)fprintf(stderr, "%.*s",
				    (int)bl->dsize, bl->bytes + bl->ksize);
			break;
		case P_RLEAF:
			rl = GETRLEAF(h, cur);
			if (rl->flags & P_BIGDATA)
				(void)fprintf(stderr,
				    "big data page %u size %u",
				    *(pgno_t *)rl->bytes,
				    *(u_int32_t *)(rl->bytes + sizeof(pgno_t)));
			else if (rl->dsize)
				(void)fprintf(stderr,
				    "%.*s", (int)rl->dsize, rl->bytes);
			break;
		}
		(void)fprintf(stderr, "\n");
	}
}

/*
 * __bt_curdel --
 *	Delete the cursor.
 *
 * Parameters:
 *	t:	tree
 *    key:	referenced key (or NULL)
 *	h:	page
 *    idx:	index on page to delete
 *
 * Returns:
 *	RET_SUCCESS, RET_ERROR.
 */
static int
__bt_curdel(BTREE *t, const DBT *key, PAGE *h, u_int idx)
{
	CURSOR *c;
	EPG e;
	PAGE *pg;
	int curcopy, status;

	/*
	 * If there are duplicates, move forward or backward to one.
	 * Otherwise, copy the key into the cursor area.
	 */
	c = &t->bt_cursor;
	F_CLR(c, CURS_AFTER | CURS_BEFORE | CURS_ACQUIRE);

	curcopy = 0;
	if (!F_ISSET(t, B_NODUPS)) {
		/*
		 * We're going to have to do comparisons.  If we weren't
		 * provided a copy of the key, i.e. the user is deleting
		 * the current cursor position, get one.
		 */
		if (key == NULL) {
			e.page = h;
			e.index = idx;
			if ((status = __bt_ret(t, &e,
			    &c->key, &c->key, NULL, NULL, 1)) != RET_SUCCESS)
				return (status);
			curcopy = 1;
			key = &c->key;
		}
		/* Check previous key, if not at the beginning of the page. */
		if (idx > 0) {
			e.page = h;
			e.index = idx - 1;
			if (__bt_cmp(t, key, &e) == 0) {
				F_SET(c, CURS_BEFORE);
				goto dup2;
			}
		}
		/* Check next key, if not at the end of the page. */
		if (idx < NEXTINDEX(h) - 1) {
			e.page = h;
			e.index = idx + 1;
			if (__bt_cmp(t, key, &e) == 0) {
				F_SET(c, CURS_AFTER);
				goto dup2;
			}
		}
		/* Check previous key if at the beginning of the page. */
		if (idx == 0 && h->prevpg != P_INVALID) {
			if ((pg = mpool_get(t->bt_mp, h->prevpg, 0)) == NULL)
				return (RET_ERROR);
			e.page = pg;
			e.index = NEXTINDEX(pg) - 1;
			if (__bt_cmp(t, key, &e) == 0) {
				F_SET(c, CURS_BEFORE);
				goto dup1;
			}
			mpool_put(t->bt_mp, pg, 0);
		}
		/* Check next key if at the end of the page. */
		if (idx == NEXTINDEX(h) - 1 && h->nextpg != P_INVALID) {
			if ((pg = mpool_get(t->bt_mp, h->nextpg, 0)) == NULL)
				return (RET_ERROR);
			e.page = pg;
			e.index = 0;
			if (__bt_cmp(t, key, &e) == 0) {
				F_SET(c, CURS_AFTER);
dup1:				mpool_put(t->bt_mp, pg, 0);
dup2:				c->pg.pgno = e.page->pgno;
				c->pg.index = e.index;
				return (RET_SUCCESS);
			}
			mpool_put(t->bt_mp, pg, 0);
		}
	}
	e.page = h;
	e.index = idx;
	if (curcopy || (status =
	    __bt_ret(t, &e, &c->key, &c->key, NULL, NULL, 1)) == RET_SUCCESS) {
		F_SET(c, CURS_ACQUIRE);
		return (RET_SUCCESS);
	}
	return (status);
}

/*
 * __bt_bdelete --
 *	Delete all key/data pairs matching the specified key.
 *
 * Parameters:
 *	  t:	tree
 *	key:	key to delete
 *
 * Returns:
 *	RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found.
 */
static int
__bt_bdelete(BTREE *t, const DBT *key)
{
	EPG *e;
	PAGE *h;
	int deleted, exact, redo;

	deleted = 0;

	/* Find any matching record; __bt_search pins the page. */
loop:	if ((e = __bt_search(t, key, &exact)) == NULL)
		return (deleted ? RET_SUCCESS : RET_ERROR);
	if (!exact) {
		mpool_put(t->bt_mp, e->page, 0);
		return (deleted ? RET_SUCCESS : RET_SPECIAL);
	}

	/*
	 * Delete forward, then delete backward, from the found key.  If
	 * there are duplicates and we reach either side of the page, do
	 * the key search again, so that we get them all.
	 */
	redo = 0;
	h = e->page;
	do {
		if (__bt_dleaf(t, key, h, e->index)) {
			mpool_put(t->bt_mp, h, 0);
			return (RET_ERROR);
		}
		if (F_ISSET(t, B_NODUPS)) {
			if (NEXTINDEX(h) == 0) {
				if (__bt_pdelete(t, h))
					return (RET_ERROR);
			} else
				mpool_put(t->bt_mp, h, MPOOL_DIRTY);
			return (RET_SUCCESS);
		}
		deleted = 1;
	} while (e->index < NEXTINDEX(h) && __bt_cmp(t, key, e) == 0);

	/* Check for right-hand edge of the page. */
	if (e->index == NEXTINDEX(h))
		redo = 1;

	/* Delete from the key to the beginning of the page. */
	while (e->index-- > 0) {
		if (__bt_cmp(t, key, e) != 0)
			break;
		if (__bt_dleaf(t, key, h, e->index) == RET_ERROR) {
			mpool_put(t->bt_mp, h, 0);
			return (RET_ERROR);
		}
		if (e->index == 0)
			redo = 1;
	}

	/* Check for an empty page. */
	if (NEXTINDEX(h) == 0) {
		if (__bt_pdelete(t, h))
			return (RET_ERROR);
		goto loop;
	}

	/* Put the page. */
	mpool_put(t->bt_mp, h, MPOOL_DIRTY);

	if (redo)
		goto loop;
	return (RET_SUCCESS);
}

/*
 * __bt_pdelete --
 *	Delete a single page from the tree.
 *
 * Parameters:
 *	t:	tree
 *	h:	leaf page
 *
 * Returns:
 *	RET_SUCCESS, RET_ERROR.
 *
 * Side-effects:
 *	mpool_put's the page
 */
static int
__bt_pdelete(BTREE *t, PAGE *h)
{
	BINTERNAL *bi;
	PAGE *pg;
	EPGNO *parent;
	indx_t cnt, idx, *ip, offset;
	u_int32_t nksize;
	char *from;

	/*
	 * Walk the parent page stack -- a LIFO stack of the pages that were
	 * traversed when we searched for the page where the delete occurred.
	 * Each stack entry is a page number and a page index offset.  The
	 * offset is for the page traversed on the search.  We've just deleted
	 * a page, so we have to delete the key from the parent page.
	 *
	 * If the delete from the parent page makes it empty, this process may
	 * continue all the way up the tree.  We stop if we reach the root page
	 * (which is never deleted, it's just not worth the effort) or if the
	 * delete does not empty the page.
	 */
	while ((parent = BT_POP(t)) != NULL) {
		/* Get the parent page. */
		if ((pg = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL)
			return (RET_ERROR);

		idx = parent->index;
		bi = GETBINTERNAL(pg, idx);

		/* Free any overflow pages. */
		if (bi->flags & P_BIGKEY &&
		    __ovfl_delete(t, bi->bytes) == RET_ERROR) {
			mpool_put(t->bt_mp, pg, 0);
			return (RET_ERROR);
		}

		/*
		 * Free the parent if it has only the one key and it's not the
		 * root page. If it's the rootpage, turn it back into an empty
		 * leaf page.
		 */
		if (NEXTINDEX(pg) == 1) {
			if (pg->pgno == P_ROOT) {
				pg->lower = BTDATAOFF;
				pg->upper = t->bt_psize;
				pg->flags = P_BLEAF;
			} else {
				if (__bt_relink(t, pg) || __bt_free(t, pg))
					return (RET_ERROR);
				continue;
			}
		} else {
			/* Pack remaining key items at the end of the page. */
			nksize = NBINTERNAL(bi->ksize);
			from = (char *)pg + pg->upper;
			memmove(from + nksize, from, (char *)bi - from);
			pg->upper += nksize;

			/* Adjust indices' offsets, shift the indices down. */
			offset = pg->linp[idx];
			for (cnt = idx, ip = &pg->linp[0]; cnt--; ++ip)
				if (ip[0] < offset)
					ip[0] += nksize;
			for (cnt = NEXTINDEX(pg) - idx; --cnt; ++ip)
				ip[0] = ip[1] < offset ? ip[1] + nksize : ip[1];
			pg->lower -= sizeof(indx_t);
		}

		mpool_put(t->bt_mp, pg, MPOOL_DIRTY);
		break;
	}

	/* Free the leaf page, as long as it wasn't the root. */
	if (h->pgno == P_ROOT) {
		mpool_put(t->bt_mp, h, MPOOL_DIRTY);
		return (RET_SUCCESS);
	}
	return (__bt_relink(t, h) || __bt_free(t, h));
}

/*
 * __REC_IPUT -- Add a recno item to the tree.
 *
 * Parameters:
 *	t:	tree
 *	nrec:	record number
 *	data:	data
 *
 * Returns:
 *	RET_ERROR, RET_SUCCESS
 */
int
__rec_iput(BTREE *t, recno_t nrec, const DBT *data, u_int flags)
{
    DBT tdata;
    EPG *e;
    PAGE *h;
    indx_t idx, nxtindex;
    pgno_t pg;
    uint32_t nbytes;
    int dflags, status;
    char *dest, db[NOVFLSIZE];

    /*
     * If the data won't fit on a page, store it on indirect pages.
     *
     * XXX
     * If the insert fails later on, these pages aren't recovered.
     */
    if (data->size > t->bt_ovflsize) {
        if (__ovfl_put(t, data, &pg) == RET_ERROR)
            return (RET_ERROR);
        tdata.data = db;
        tdata.size = NOVFLSIZE;
        *(pgno_t *)(void *)db = pg;
        _DBFIT(data->size, uint32_t);
        *(uint32_t *)(void *)(db + sizeof(pgno_t)) =
            (uint32_t)data->size;
        dflags = P_BIGDATA;
        data = &tdata;
    } else
        dflags = 0;

    /* __rec_search pins the returned page. */
    if ((e = __rec_search(t, nrec,
                          nrec > t->bt_nrecs || flags == R_IAFTER || flags == R_IBEFORE ?
                          SINSERT : SEARCH)) == NULL)
        return (RET_ERROR);

    h = e->page;
    idx = e->index;

    /*
     * Add the specified key/data pair to the tree.  The R_IAFTER and
     * R_IBEFORE flags insert the key after/before the specified key.
     *
     * Pages are split as required.
     */
    switch (flags) {
    case R_IAFTER:
        ++idx;
        break;
    case R_IBEFORE:
        break;
    default:
        if (nrec < t->bt_nrecs &&
                __rec_dleaf(t, h, (uint32_t)idx) == RET_ERROR) {
            mpool_put(t->bt_mp, h, 0);
            return (RET_ERROR);
        }
        break;
    }

    /*
     * If not enough room, split the page.  The split code will insert
     * the key and data and unpin the current page.  If inserting into
     * the offset array, shift the pointers up.
     */
    nbytes = NRLEAFDBT(data->size);
    if ((uint32_t) (h->upper - h->lower) < nbytes + sizeof(indx_t)) {
        status = __bt_split(t, h, NULL, data, dflags, nbytes,
                            (uint32_t)idx);
        if (status == RET_SUCCESS)
            ++t->bt_nrecs;
        return (status);
    }

    if (idx < (nxtindex = NEXTINDEX(h)))
        memmove(h->linp + idx + 1, h->linp + idx,
                (nxtindex - idx) * sizeof(indx_t));
    h->lower += sizeof(indx_t);

    h->linp[idx] = h->upper -= nbytes;
    dest = (char *)(void *)h + h->upper;
    WR_RLEAF(dest, data, dflags);

    ++t->bt_nrecs;
    F_SET(t, B_MODIFIED);
    mpool_put(t->bt_mp, h, MPOOL_DIRTY);

//.........这里部分代码省略.........

/*
 * __bt_stkacq --
 *	Acquire a stack so we can delete a cursor entry.
 *
 * Parameters:
 *	  t:	tree
 *	 hp:	pointer to current, pinned PAGE pointer
 *	  c:	pointer to the cursor
 *
 * Returns:
 *	0 on success, 1 on failure
 */
static int
__bt_stkacq(BTREE *t, PAGE **hp, CURSOR *c)
{
	BINTERNAL *bi;
	EPG *e;
	EPGNO *parent;
	PAGE *h;
	indx_t idx;
	pgno_t pgno;
	recno_t nextpg, prevpg;
	int exact, level;

	/*
	 * Find the first occurrence of the key in the tree.  Toss the
	 * currently locked page so we don't hit an already-locked page.
	 */
	h = *hp;
	mpool_put(t->bt_mp, h, 0);
	if ((e = __bt_search(t, &c->key, &exact)) == NULL)
		return (1);
	h = e->page;

	/* See if we got it in one shot. */
	if (h->pgno == c->pg.pgno)
		goto ret;

	/*
	 * Move right, looking for the page.  At each move we have to move
	 * up the stack until we don't have to move to the next page.  If
	 * we have to change pages at an internal level, we have to fix the
	 * stack back up.
	 */
	while (h->pgno != c->pg.pgno) {
		if ((nextpg = h->nextpg) == P_INVALID)
			break;
		mpool_put(t->bt_mp, h, 0);

		/* Move up the stack. */
		for (level = 0; (parent = BT_POP(t)) != NULL; ++level) {
			/* Get the parent page. */
			if ((h = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL)
				return (1);

			/* Move to the next index. */
			if (parent->index != NEXTINDEX(h) - 1) {
				idx = parent->index + 1;
				BT_PUSH(t, h->pgno, idx);
				break;
			}
			mpool_put(t->bt_mp, h, 0);
		}

		/* Restore the stack. */
		while (level--) {
			/* Push the next level down onto the stack. */
			bi = GETBINTERNAL(h, idx);
			pgno = bi->pgno;
			BT_PUSH(t, pgno, 0);

			/* Lose the currently pinned page. */
			mpool_put(t->bt_mp, h, 0);

			/* Get the next level down. */
			if ((h = mpool_get(t->bt_mp, pgno, 0)) == NULL)
				return (1);
			idx = 0;
		}
		mpool_put(t->bt_mp, h, 0);
		if ((h = mpool_get(t->bt_mp, nextpg, 0)) == NULL)
			return (1);
	}

	if (h->pgno == c->pg.pgno)
		goto ret;

	/* Reacquire the original stack. */
	mpool_put(t->bt_mp, h, 0);
	if ((e = __bt_search(t, &c->key, &exact)) == NULL)
		return (1);
	h = e->page;

	/*
	 * Move left, looking for the page.  At each move we have to move
	 * up the stack until we don't have to change pages to move to the
	 * next page.  If we have to change pages at an internal level, we
	 * have to fix the stack back up.
	 */
	while (h->pgno != c->pg.pgno) {
//.........这里部分代码省略.........

/*
 * __bt_seqadvance --
 *	Advance the sequential scan.
 *
 * Parameters:
 *	t:	tree
 *	flags:	R_NEXT, R_PREV
 *
 * Side effects:
 *	Pins the page the new key/data record is on.
 *
 * Returns:
 *	RET_ERROR, RET_SUCCESS or RET_SPECIAL if there's no next key.
 */
static int
__bt_seqadv(BTREE *t, EPG *ep, int flags)
{
	CURSOR *c;
	PAGE *h;
	indx_t idx = 0;	/* pacify gcc */
	pgno_t pg;
	int exact;

	/*
	 * There are a couple of states that we can be in.  The cursor has
	 * been initialized by the time we get here, but that's all we know.
	 */
	c = &t->bt_cursor;

	/*
	 * The cursor was deleted where there weren't any duplicate records,
	 * so the key was saved.  Find out where that key would go in the
	 * current tree.  It doesn't matter if the returned key is an exact
	 * match or not -- if it's an exact match, the record was added after
	 * the delete so we can just return it.  If not, as long as there's
	 * a record there, return it.
	 */
	if (F_ISSET(c, CURS_ACQUIRE))
		return (__bt_first(t, &c->key, ep, &exact));

	/* Get the page referenced by the cursor. */
	if ((h = mpool_get(t->bt_mp, c->pg.pgno, 0)) == NULL)
		return (RET_ERROR);

	/*
 	 * Find the next/previous record in the tree and point the cursor at
	 * it.  The cursor may not be moved until a new key has been found.
	 */
	switch (flags) {
	case R_NEXT:			/* Next record. */
		/*
		 * The cursor was deleted in duplicate records, and moved
		 * forward to a record that has yet to be returned.  Clear
		 * that flag, and return the record.
		 */
		if (F_ISSET(c, CURS_AFTER))
			goto usecurrent;
		idx = c->pg.index;
		if (++idx == NEXTINDEX(h)) {
			pg = h->nextpg;
			mpool_put(t->bt_mp, h, 0);
			if (pg == P_INVALID)
				return (RET_SPECIAL);
			if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
				return (RET_ERROR);
			idx = 0;
		}
		break;
	case R_PREV:			/* Previous record. */
		/*
		 * The cursor was deleted in duplicate records, and moved
		 * backward to a record that has yet to be returned.  Clear
		 * that flag, and return the record.
		 */
		if (F_ISSET(c, CURS_BEFORE)) {
usecurrent:		F_CLR(c, CURS_AFTER | CURS_BEFORE);
			ep->page = h;
			ep->index = c->pg.index;
			return (RET_SUCCESS);
		}
		idx = c->pg.index;
		if (idx == 0) {
			pg = h->prevpg;
			mpool_put(t->bt_mp, h, 0);
			if (pg == P_INVALID)
				return (RET_SPECIAL);
			if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
				return (RET_ERROR);
			idx = NEXTINDEX(h) - 1;
		} else
			--idx;
		break;
	}

	ep->page = h;
	ep->index = idx;
	return (RET_SUCCESS);
}