/*
- * Copyright (C) 2002 by the Massachusetts Institute of Technology.
+ * Copyright (C) 2002, 2016 by the Massachusetts Institute of Technology.
* All rights reserved.
*
* Export of this software from the United States of America may
static int __bt_seqadv __P((BTREE *, EPG *, int));
static int __bt_seqset __P((BTREE *, EPG *, DBT *, int));
+static int bt_rseq_next(BTREE *, EPG *);
+static int bt_rseq_prev(BTREE *, EPG *);
+
/*
* Sequential scan support.
*
switch (flags) {
case R_NEXT:
case R_PREV:
+ case R_RNEXT:
+ case R_RPREV:
if (F_ISSET(&t->bt_cursor, CURS_INIT)) {
status = __bt_seqadv(t, &e, flags);
break;
return (__bt_first(t, key, ep, &exact));
case R_FIRST: /* First record. */
case R_NEXT:
+ case R_RNEXT:
+ BT_CLR(t);
/* Walk down the left-hand side of the tree. */
for (pg = P_ROOT;;) {
if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
if (h->flags & (P_BLEAF | P_RLEAF))
break;
pg = GETBINTERNAL(h, 0)->pgno;
+ BT_PUSH(t, h->pgno, 0);
mpool_put(t->bt_mp, h, 0);
}
ep->page = h;
break;
case R_LAST: /* Last record. */
case R_PREV:
+ case R_RPREV:
+ BT_CLR(t);
/* Walk down the right-hand side of the tree. */
for (pg = P_ROOT;;) {
if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
if (h->flags & (P_BLEAF | P_RLEAF))
break;
pg = GETBINTERNAL(h, NEXTINDEX(h) - 1)->pgno;
+ BT_PUSH(t, h->pgno, NEXTINDEX(h) - 1);
mpool_put(t->bt_mp, h, 0);
}
*/
switch (flags) {
case R_NEXT: /* Next record. */
+ case R_RNEXT:
/*
* The cursor was deleted in duplicate records, and moved
* forward to a record that has yet to be returned. Clear
goto usecurrent;
idx = c->pg.index;
if (++idx == NEXTINDEX(h)) {
+ if (flags == R_RNEXT) {
+ ep->page = h;
+ ep->index = idx;
+ return (bt_rseq_next(t, ep));
+ }
pg = h->nextpg;
mpool_put(t->bt_mp, h, 0);
if (pg == P_INVALID)
}
break;
case R_PREV: /* Previous record. */
+ case R_RPREV:
/*
* The cursor was deleted in duplicate records, and moved
* backward to a record that has yet to be returned. Clear
}
idx = c->pg.index;
if (idx == 0) {
+ if (flags == R_RPREV) {
+ ep->page = h;
+ ep->index = idx;
+ return (bt_rseq_prev(t, ep));
+ }
pg = h->prevpg;
mpool_put(t->bt_mp, h, 0);
if (pg == P_INVALID)
return (RET_SUCCESS);
}
+/*
+ * Get the first item on the next page, but by going up and down the tree.
+ */
+static int
+bt_rseq_next(BTREE *t, EPG *ep)
+{
+ PAGE *h;
+ indx_t idx;
+ EPGNO *up;
+ db_pgno_t pg;
+
+ h = ep->page;
+ idx = ep->index;
+ do {
+ /* Move up the tree. */
+ up = BT_POP(t);
+ mpool_put(t->bt_mp, h, 0);
+ /* Did we hit the right edge of the root? */
+ if (up == NULL)
+ return (RET_SPECIAL);
+ if ((h = mpool_get(t->bt_mp, up->pgno, 0)) == NULL)
+ return (RET_ERROR);
+ idx = up->index;
+ } while (++idx == NEXTINDEX(h));
+
+ while (!(h->flags & (P_BLEAF | P_RLEAF))) {
+ /* Move back down the tree. */
+ BT_PUSH(t, h->pgno, idx);
+ pg = GETBINTERNAL(h, idx)->pgno;
+ mpool_put(t->bt_mp, h, 0);
+ if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
+ return (RET_ERROR);
+ idx = 0;
+ }
+ ep->page = h;
+ ep->index = idx;
+ return (RET_SUCCESS);
+}
+
+/*
+ * Get the last item on the previous page, but by going up and down the tree.
+ */
+static int
+bt_rseq_prev(BTREE *t, EPG *ep)
+{
+ PAGE *h;
+ indx_t idx;
+ EPGNO *up;
+ db_pgno_t pg;
+
+ h = ep->page;
+ idx = ep->index;
+ do {
+ /* Move up the tree. */
+ up = BT_POP(t);
+ mpool_put(t->bt_mp, h, 0);
+ /* Did we hit the left edge of the root? */
+ if (up == NULL)
+ return (RET_SPECIAL);
+ if ((h = mpool_get(t->bt_mp, up->pgno, 0)) == NULL)
+ return (RET_ERROR);
+ idx = up->index;
+ } while (idx == 0);
+ --idx;
+ while (!(h->flags & (P_BLEAF | P_RLEAF))) {
+ /* Move back down the tree. */
+ BT_PUSH(t, h->pgno, idx);
+ pg = GETBINTERNAL(h, idx)->pgno;
+ mpool_put(t->bt_mp, h, 0);
+ if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
+ return (RET_ERROR);
+ idx = NEXTINDEX(h) - 1;
+ }
+ ep->page = h;
+ ep->index = idx;
+ return (RET_SUCCESS);
+}
+
/*
* __bt_first --
* Find the first entry.
t->bt_cursor.pg.index = idx;
F_SET(&t->bt_cursor, CURS_INIT);
}
-
-/* Recursive descent cursor. */
-typedef struct rcursor_ {
- CURSOR cursor;
- size_t ssize;
- EPGNO *stack;
- EPGNO *sp;
-} RCURSOR;
-#define RCURSOR_MINSS 64
-
-static int bt_rcinit(void **);
-static void bt_rcdestroy(void **);
-static int bt_rcpush(RCURSOR *, db_pgno_t, u_int);
-static EPGNO *bt_rcpop(RCURSOR *);
-static void bt_rcclr(RCURSOR *);
-static int bt_rcgrowstk(RCURSOR *);
-static int bt_rseqset(BTREE *, EPG *, DBT *, RCURSOR *, int);
-static int bt_rseqadv(BTREE *, EPG *, RCURSOR *, int);
-
-static int
-bt_rcinit(curs)
- void **curs;
-{
- RCURSOR *rc;
-
- rc = *curs = malloc(sizeof(RCURSOR));
- if (rc == NULL) {
- errno = ENOMEM;
- return RET_ERROR;
- }
- memset(rc, 0, sizeof(*rc));
-
- rc->ssize = RCURSOR_MINSS;
- rc->stack = malloc(rc->ssize * sizeof(EPGNO));
- if (rc->stack == NULL) {
- free(rc);
- errno = ENOMEM;
- return RET_ERROR;
- }
- bt_rcclr(rc);
- return RET_SUCCESS;
-}
-
-static void
-bt_rcdestroy(curs)
- void **curs;
-{
- RCURSOR *rc;
-
- rc = *curs;
- free(rc->stack);
- free(rc);
- *curs = NULL;
-}
-
-static int
-bt_rcpush(rc, p, i)
- RCURSOR *rc;
- db_pgno_t p;
- u_int i;
-{
- int status;
-
- rc->sp->pgno = p;
- rc->sp->index = i;
- if (++rc->sp > rc->stack + rc->ssize) {
- status = bt_rcgrowstk(rc);
- if (status != RET_SUCCESS)
- return status;
- }
- return RET_SUCCESS;
-}
-
-static EPGNO *
-bt_rcpop(rc)
- RCURSOR *rc;
-{
- return (rc->sp == rc->stack) ? NULL : --rc->sp;
-}
-
-static void
-bt_rcclr(rc)
- RCURSOR *rc;
-{
- rc->sp = rc->stack;
-}
-
-static int
-bt_rcgrowstk(rc)
- RCURSOR *rc;
-{
- size_t osize;
- EPGNO *e;
-
- osize = rc->ssize;
- rc->ssize *= 2;
- e = realloc(rc->stack, rc->ssize * sizeof(EPGNO));
- if (e == NULL) {
- rc->ssize = osize;
- errno = ENOMEM;
- return RET_ERROR;
- }
- rc->stack = e;
- return RET_SUCCESS;
-}
-
-/*
- * bt_rseq --
- * Like __bt_seq but does recursive descent tree traversal
- * instead of using the prev/next pointers.
- */
-int
-bt_rseq(dbp, key, data, curs, flags)
- const DB *dbp;
- DBT *key, *data;
- void **curs;
- u_int flags;
-{
- RCURSOR *rc;
- BTREE *t;
- EPG e;
- 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;
- }
-
- if (curs == NULL) {
- errno = EINVAL;
- return RET_ERROR;
- }
- if (*curs == NULL) {
- status = bt_rcinit(curs);
- if (status != RET_SUCCESS)
- return RET_ERROR;
- }
- rc = *curs;
-
- /*
- * If scan unitialized as yet, or starting at a specific record, set
- * the scan to a specific key. Both bt_rseqset and bt_rseqadv pin
- * the page the cursor references if they're successful.
- */
- switch (flags) {
- case R_NEXT:
- case R_PREV:
- if (F_ISSET(&rc->cursor, CURS_INIT)) {
- status = bt_rseqadv(t, &e, rc, flags);
- break;
- }
- /* FALLTHROUGH */
- case R_FIRST:
- case R_LAST:
- case R_CURSOR:
- status = bt_rseqset(t, &e, key, rc, flags);
- break;
- default:
- errno = EINVAL;
- return (RET_ERROR);
- }
-
- if (status == RET_SUCCESS) {
- status =
- __bt_ret(t, &e, key, &t->bt_rkey, data, &t->bt_rdata, 0);
-
- /*
- * If the user is doing concurrent access, we copied the
- * key/data, toss the page.
- */
- if (F_ISSET(t, B_DB_LOCK))
- mpool_put(t->bt_mp, e.page, 0);
- else
- t->bt_pinned = e.page;
- } else if (status == RET_SPECIAL)
- bt_rcdestroy(curs);
- return (status);
-}
-
-/*
- * bt_rseqset --
- * Set the sequential scan to a specific key.
- *
- * Parameters:
- * t: tree
- * ep: storage for returned key
- * key: key for initial scan position
- * rc: recursion cursor
- * flags: R_CURSOR, R_FIRST, R_LAST, R_NEXT, R_PREV
- *
- * Side effects:
- * Pins the page the cursor references.
- * Updates rc's stack and cursor.
- *
- * Returns:
- * RET_ERROR, RET_SUCCESS or RET_SPECIAL if there's no next key.
- */
-static int
-bt_rseqset(t, ep, key, rc, flags)
- BTREE *t;
- EPG *ep;
- DBT *key;
- RCURSOR *rc;
- int flags;
-{
- PAGE *h;
- db_pgno_t pg;
- int status;
-
- /*
- * 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: /* Not implemented. */
- errno = EINVAL;
- return RET_ERROR;
- case R_FIRST: /* First record. */
- case R_NEXT:
- bt_rcclr(rc);
- /* 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;
- status = bt_rcpush(rc, h->pgno, 0);
- mpool_put(t->bt_mp, h, 0);
- if (status != RET_SUCCESS)
- return status;
- }
- ep->page = h;
- ep->index = 0;
- break;
- case R_LAST: /* Last record. */
- case R_PREV:
- bt_rcclr(rc);
- /* 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;
- status = bt_rcpush(rc, h->pgno, NEXTINDEX(h) - 1);
- mpool_put(t->bt_mp, h, 0);
- if (status != RET_SUCCESS)
- return status;
- }
- ep->page = h;
- ep->index = NEXTINDEX(h) - 1;
- break;
- }
- rc->cursor.pg.pgno = ep->page->pgno;
- rc->cursor.pg.index = ep->index;
- F_CLR(&rc->cursor, CURS_ACQUIRE | CURS_AFTER | CURS_BEFORE);
- F_SET(&rc->cursor, CURS_INIT);
- return (RET_SUCCESS);
-}
-
-/*
- * bt_rseqadvance --
- * Advance the sequential scan.
- *
- * Parameters:
- * t: tree
- * ep: return page
- * rc: recursion cursor
- * flags: R_NEXT, R_PREV
- *
- * Side effects:
- * Pins the page the new key/data record is on.
- * Updates rc's stack and cursor.
- *
- * Returns:
- * RET_ERROR, RET_SUCCESS or RET_SPECIAL if there's no next key.
- */
-static int
-bt_rseqadv(t, ep, rc, flags)
- BTREE *t;
- EPG *ep;
- RCURSOR *rc;
- int flags;
-{
- CURSOR *c;
- PAGE *h;
- indx_t idx = 0;
- db_pgno_t pg;
- int status;
- EPGNO *e;
-
- /*
- * 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 = &rc->cursor;
-
- /* 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. */
- idx = c->pg.index;
- while (++idx == NEXTINDEX(h)) {
- /* Crawl up if we hit the right edge. */
- e = bt_rcpop(rc);
- mpool_put(t->bt_mp, h, 0);
- if (e == NULL) /* Hit the right edge of root. */
- return RET_SPECIAL;
- idx = e->index;
- pg = e->pgno;
- if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
- return (RET_ERROR);
- }
- while (!(h->flags & (P_BLEAF | P_RLEAF))) {
- /* Crawl down the left until we hit a leaf. */
- status = bt_rcpush(rc, h->pgno, idx);
- pg = GETBINTERNAL(h, idx)->pgno;
- mpool_put(t->bt_mp, h, 0);
- if (status != RET_SUCCESS)
- return status;
- if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
- return (RET_ERROR);
- idx = 0;
- }
- break;
- case R_PREV: /* Previous record. */
- idx = c->pg.index;
- while (!idx) {
- /* Crawl up if we hit the left edge. */
- e = bt_rcpop(rc);
- mpool_put(t->bt_mp, h, 0);
- if (e == NULL) /* Hit the left edge of root. */
- return RET_SPECIAL;
- idx = e->index;
- pg = e->pgno;
- if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
- return (RET_ERROR);
- }
- idx--;
- while (!(h->flags & (P_BLEAF | P_RLEAF))) {
- /* Crawl down the right until we hit a leaf. */
- status = bt_rcpush(rc, h->pgno, idx);
- pg = GETBINTERNAL(h, idx)->pgno;
- mpool_put(t->bt_mp, h, 0);
- if (status != RET_SUCCESS)
- return status;
- if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
- return (RET_ERROR);
- idx = NEXTINDEX(h) - 1;
- }
- break;
- }
-
- ep->page = h;
- ep->index = idx;
- c->pg.pgno = h->pgno;
- c->pg.index = idx;
- F_CLR(c, CURS_ACQUIRE | CURS_AFTER | CURS_BEFORE);
- F_SET(c, CURS_INIT);
- return (RET_SUCCESS);
-}
projects / thirdparty / krb5.git / commitdiff
