bt_seq.c File Reference

#include <sys/types.h>
#include <errno.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include "../include/db.h"
#include "btree.h"

Include dependency graph for bt_seq.c:

Go to the source code of this file.

Functions
static int	__bt_first (BTREE *t, const DBT *key, EPG *erval, int *exactp)
int	__bt_seq (DB *dbp, DBT *key, DBT *data, u_int flags) const
static int	__bt_seqadv (BTREE *t, EPG *ep, int flags)
static int	__bt_seqset (BTREE *t, EPG *ep, DBT *key, int flags)
void	__bt_setcur (BTREE *t, pgno_t pgno, u_int index)
static int __bt_first	__P ((BTREE *, const DBT *, EPG *, int *))
static int __bt_seqadv	__P ((BTREE *, EPG *, int))
static int __bt_seqset	__P ((BTREE *, EPG *, DBT *, int))

Function Documentation

__bt_first()

static int __bt_first ( BTREE *  t, const DBT *  key, EPG *  erval, int *  exactp  )

static

Definition at line 342 of file bt_seq.c.

References __bt_cmp(), __bt_search(), B_NODUPS, _btree::bt_mp, F_ISSET, _epg::index, mpool_get(), mpool_put(), NEXTINDEX, _page::nextpg, NULL, P_INVALID, _epg::page, _page::pgno, _page::prevpg, RET_ERROR, RET_SPECIAL, and RET_SUCCESS.

Referenced by __bt_seqadv(), and __bt_seqset().

{
   PAGE *h;
   EPG *ep, save;
   pgno_t pg;

   /*
    * Find any matching record; __bt_search pins the page.
    *
    * If it's an exact match and duplicates are possible, walk backwards
    * in the tree until we find the first one.  Otherwise, make sure it's
    * a valid key (__bt_search may return an index just past the end of a
    * page) and return it.
    */
   if ((ep = __bt_search(t, key, exactp)) == NULL)
      return (RET_SPECIAL);
   if (*exactp) {
      if (F_ISSET(t, B_NODUPS)) {
         *erval = *ep;
         return (RET_SUCCESS);
      }

      /*
       * Walk backwards, as long as the entry matches and there are
       * keys left in the tree.  Save a copy of each match in case
       * we go too far.
       */
      save = *ep;
      h = ep->page;
      do {
         if (save.page->pgno != ep->page->pgno) {
            mpool_put(t->bt_mp, save.page, 0);
            save = *ep;
         } else
            save.index = ep->index;

         /*
          * Don't unpin the page the last (or original) match
          * was on, but make sure it's unpinned if an error
          * occurs.
          */
         if (ep->index == 0) {
            if (h->prevpg == P_INVALID)
               break;
            if (h->pgno != save.page->pgno)
               mpool_put(t->bt_mp, h, 0);
            if ((h = mpool_get(t->bt_mp,
                h->prevpg, 0)) == NULL) {
               if (h->pgno == save.page->pgno)
                  mpool_put(t->bt_mp,
                      save.page, 0);
               return (RET_ERROR);
            }
            ep->page = h;
            ep->index = NEXTINDEX(h);
         }
         --ep->index;
      } while (__bt_cmp(t, key, ep) == 0);

      /*
       * Reach here with the last page that was looked at pinned,
       * which may or may not be the same as the last (or original)
       * match page.  If it's not useful, release it.
       */
      if (h->pgno != save.page->pgno)
         mpool_put(t->bt_mp, h, 0);

      *erval = save;
      return (RET_SUCCESS);
   }

   /* If at the end of a page, find the next entry. */
   if (ep->index == NEXTINDEX(ep->page)) {
      h = ep->page;
      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);
      ep->index = 0;
      ep->page = h;
   }
   *erval = *ep;
   return (RET_SUCCESS);
}

__bt_seq()

int __bt_seq	(	DB *	dbp,
		DBT *	key,
		DBT *	data,
		u_int	flags
	)		const

Definition at line 77 of file bt_seq.c.

References __bt_ret(), __bt_seqadv(), __bt_seqset(), __bt_setcur(), B_DB_LOCK, _btree::bt_cursor, _btree::bt_mp, _btree::bt_pinned, _btree::bt_rdata, _btree::bt_rkey, CURS_INIT, errno, F_ISSET, _epg::index, __db::internal, mpool_put(), NULL, _epg::page, _page::pgno, R_CURSOR, R_FIRST, R_LAST, R_NEXT, R_PREV, RET_ERROR, RET_SUCCESS, and status.

Referenced by __bt_open().

{
   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 scan uninitialized as yet, or starting at a specific record, set
    * the scan to a specific key.  Both __bt_seqset and __bt_seqadv pin
    * the page the cursor references if they're successful.
    */
   switch (flags) {
   case R_NEXT:
   case R_PREV:
      if (F_ISSET(&t->bt_cursor, CURS_INIT)) {
         status = __bt_seqadv(t, &e, flags);
         break;
      }
      /* FALLTHROUGH */
   case R_FIRST:
   case R_LAST:
   case R_CURSOR:
      status = __bt_seqset(t, &e, key, flags);
      break;
   default:
      errno = EINVAL;
      return (RET_ERROR);
   }

   if (status == RET_SUCCESS) {
      __bt_setcur(t, e.page->pgno, e.index);

      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;
   }
   return (status);
}

__bt_seqadv()

static int __bt_seqadv ( BTREE *  t, EPG *  ep, int  flags  )

static

Definition at line 240 of file bt_seq.c.

References __bt_first(), _btree::bt_cursor, _btree::bt_mp, c, CURS_ACQUIRE, CURS_AFTER, CURS_BEFORE, F_CLR, F_ISSET, _epgno::index, _epg::index, _cursor::key, mpool_get(), mpool_put(), NEXTINDEX, _page::nextpg, NULL, P_INVALID, _epg::page, _cursor::pg, _epgno::pgno, _page::prevpg, R_NEXT, R_PREV, RET_ERROR, RET_SPECIAL, and RET_SUCCESS.

Referenced by __bt_seq().

{
   CURSOR *c;
   PAGE *h;
   indx_t index = 0;
   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;
      index = c->pg.index;
      if (++index == 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);
         index = 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);
      }
      index = c->pg.index;
      if (index == 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);
         index = NEXTINDEX(h) - 1;
      } else
         --index;
      break;
   }

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

__bt_seqset()

static int __bt_seqset ( BTREE *  t, EPG *  ep, DBT *  key, int  flags  )

static

Definition at line 152 of file bt_seq.c.

References __bt_first(), _btree::bt_mp, DBT::data, errno, _page::flags, GETBINTERNAL, _epg::index, mpool_get(), mpool_put(), NEXTINDEX, NULL, P_BLEAF, P_RLEAF, P_ROOT, _epg::page, R_CURSOR, R_FIRST, R_LAST, R_NEXT, R_PREV, RET_ERROR, RET_SPECIAL, RET_SUCCESS, and DBT::size.

Referenced by __bt_seq().

{
   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_setcur()

void __bt_setcur	(	BTREE *	t,
		pgno_t	pgno,
		u_int	index
	)

Definition at line 443 of file bt_seq.c.

References _btree::bt_cursor, CURS_ACQUIRE, CURS_AFTER, CURS_BEFORE, CURS_INIT, DBT::data, F_CLR, F_SET, free(), _epgno::index, _cursor::key, NULL, _cursor::pg, _epgno::pgno, and DBT::size.

Referenced by __bt_put(), and __bt_seq().

{
   /* Lose any already deleted key. */
   if (t->bt_cursor.key.data != NULL) {
      free(t->bt_cursor.key.data);
      t->bt_cursor.key.size = 0;
      t->bt_cursor.key.data = NULL;
   }
   F_CLR(&t->bt_cursor, CURS_ACQUIRE | CURS_AFTER | CURS_BEFORE);

   /* Update the cursor. */
   t->bt_cursor.pg.pgno = pgno;
   t->bt_cursor.pg.index = index;
   F_SET(&t->bt_cursor, CURS_INIT);
}

__P() [1/3]

static int __bt_first __P ( (BTREE *, const DBT *, EPG *, int *)  )

static

__P() [2/3]

static int __bt_seqadv __P ( (BTREE *, EPG *, int)  )

static

__P() [3/3]

static int __bt_seqset __P ( (BTREE *, EPG *, DBT *, int)  )

static