/*
* __OVFL_DELETE -- Delete an overflow chain.
*
* Parameters:
* t: tree
* p: pointer to { pgno_t, u_int32_t }
*
* Returns:
* RET_ERROR, RET_SUCCESS
*/
int
__ovfl_delete(BTREE *t, void *p)
{
PAGE *h;
pgno_t pg;
size_t plen;
u_int32_t sz;
memmove(&pg, p, sizeof(pgno_t));
memmove(&sz, (char *)p + sizeof(pgno_t), sizeof(u_int32_t));
#ifdef DEBUG
if (pg == P_INVALID || sz == 0)
abort();
#endif
if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
return (RET_ERROR);
/* Don't delete chains used by internal pages. */
if (h->flags & P_PRESERVE) {
mpool_put(t->bt_mp, h, 0);
return (RET_SUCCESS);
}
/* Step through the chain, calling the free routine for each page. */
for (plen = t->bt_psize - BTDATAOFF;; sz -= plen) {
pg = h->nextpg;
__bt_free(t, h);
if (sz <= plen)
break;
if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
return (RET_ERROR);
}
return (RET_SUCCESS);
}
/*
* NROOT -- Create the root of a new tree.
*
* Parameters:
* t: tree
*
* Returns:
* RET_ERROR, RET_SUCCESS
*/
static int
nroot(BTREE *t)
{
PAGE *meta, *root;
pgno_t npg;
if ((meta = mpool_get(t->bt_mp, 0, 0)) != NULL) {
mpool_put(t->bt_mp, meta, 0);
return (RET_SUCCESS);
}
if (errno != EINVAL) /* It's OK to not exist. */
return (RET_ERROR);
errno = 0;
if ((meta = mpool_new(t->bt_mp, &npg)) == NULL)
return (RET_ERROR);
if ((root = mpool_new(t->bt_mp, &npg)) == NULL)
return (RET_ERROR);
if (npg != P_ROOT)
return (RET_ERROR);
root->pgno = npg;
root->prevpg = root->nextpg = P_INVALID;
root->lower = BTDATAOFF;
root->upper = t->bt_psize;
root->flags = P_BLEAF;
memset(meta, 0, t->bt_psize);
mpool_put(t->bt_mp, meta, MPOOL_DIRTY);
mpool_put(t->bt_mp, root, 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);
}
/*
* BT_DUMP -- Dump the tree
*
* Parameters:
* dbp: pointer to the DB
*/
void
__bt_dump(DB *dbp)
{
BTREE *t;
PAGE *h;
pgno_t i;
char *sep;
t = dbp->internal;
(void)fprintf(stderr, "%s: pgsz %u",
F_ISSET(t, B_INMEM) ? "memory" : "disk", t->bt_psize);
if (F_ISSET(t, R_RECNO))
(void)fprintf(stderr, " keys %u", t->bt_nrecs);
#undef X
#define X(flag, name) \
if (F_ISSET(t, flag)) { \
(void)fprintf(stderr, "%s%s", sep, name); \
sep = ", "; \
}
if (t->flags != 0) {
sep = " flags (";
X(R_FIXLEN, "FIXLEN");
X(B_INMEM, "INMEM");
X(B_NODUPS, "NODUPS");
X(B_RDONLY, "RDONLY");
X(R_RECNO, "RECNO");
X(B_METADIRTY,"METADIRTY");
(void)fprintf(stderr, ")\n");
}
#undef X
for (i = P_ROOT;
(h = mpool_get(t->bt_mp, i, MPOOL_IGNOREPIN)) != NULL; ++i)
__bt_dpage(h);
}
/*
* BT_DNPAGE -- Dump the page
*
* Parameters:
* n: page number to dump.
*/
void
__bt_dnpage(DB *dbp, pgno_t pgno)
{
BTREE *t;
PAGE *h;
t = dbp->internal;
if ((h = mpool_get(t->bt_mp, pgno, MPOOL_IGNOREPIN)) != NULL)
__bt_dpage(h);
}
/*
* __bt_relink --
* Link around a deleted page.
*
* Parameters:
* t: tree
* h: page to be deleted
*/
static int
__bt_relink(BTREE *t, PAGE *h)
{
PAGE *pg;
if (h->nextpg != P_INVALID) {
if ((pg = mpool_get(t->bt_mp, h->nextpg, 0)) == NULL)
return (RET_ERROR);
pg->prevpg = h->prevpg;
mpool_put(t->bt_mp, pg, MPOOL_DIRTY);
}
if (h->prevpg != P_INVALID) {
if ((pg = mpool_get(t->bt_mp, h->prevpg, 0)) == NULL)
return (RET_ERROR);
pg->nextpg = h->nextpg;
mpool_put(t->bt_mp, pg, MPOOL_DIRTY);
}
return (0);
}
/*
* BT_PRESERVE -- Mark a chain of pages as used by an internal node.
*
* Chains of indirect blocks pointed to by leaf nodes get reclaimed when the
* record that references them gets deleted. Chains pointed to by internal
* pages never get deleted. This routine marks a chain as pointed to by an
* internal page.
*
* Parameters:
* t: tree
* pg: page number of first page in the chain.
*
* Returns:
* RET_SUCCESS, RET_ERROR.
*/
static int
bt_preserve(BTREE *t, pgno_t pg)
{
PAGE *h;
if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
return (RET_ERROR);
h->flags |= P_PRESERVE;
mpool_put(t->bt_mp, h, MPOOL_DIRTY);
return (RET_SUCCESS);
}
/*
* BT_DNPAGE -- Dump the page
*
* Parameters:
* n: page number to dump.
*/
void
__bt_dnpage(DB *dbp, pgno_t pgno)
{
BTREE *t;
PAGE *h;
t = dbp->internal;
if ((h = mpool_get(t->bt_mp, pgno, 0)) != NULL) {
__bt_dpage(h);
(void)mpool_put(t->bt_mp, h, 0);
}
}
/*
* __bt_new --
* Get a new page, preferably from the freelist.
*
* Parameters:
* t: tree
* npg: storage for page number.
*
* Returns:
* Pointer to a page, NULL on error.
*/
PAGE *
__bt_new(BTREE *t, pgno_t *npg)
{
PAGE *h;
if (t->bt_free != P_INVALID &&
(h = mpool_get(t->bt_mp, t->bt_free, 0)) != NULL) {
*npg = t->bt_free;
t->bt_free = h->nextpg;
F_SET(t, B_METADIRTY);
return (h);
}
return (mpool_new(t->bt_mp, npg, MPOOL_PAGE_NEXT));
}
/*
* __OVFL_GET -- Get an overflow key/data item.
*
* Parameters:
* t: tree
* p: pointer to { pgno_t, uint32_t }
* buf: storage address
* bufsz: storage size
*
* Returns:
* RET_ERROR, RET_SUCCESS
*/
int
__ovfl_get(BTREE *t, void *p, size_t *ssz, void **buf, size_t *bufsz)
{
PAGE *h;
pgno_t pg;
uint32_t sz, nb, plen;
size_t temp;
memmove(&pg, p, sizeof(pg));
memmove(&sz, (char *)p + sizeof(pgno_t), sizeof(uint32_t));
*ssz = sz;
#ifdef DEBUG
if (pg == P_INVALID || sz == 0)
abort();
#endif
/* Make the buffer bigger as necessary. */
if (*bufsz < sz) {
void *nbuf = realloc(*buf, sz);
if (nbuf == NULL)
return (RET_ERROR);
*buf = nbuf;
*bufsz = sz;
}
/*
* Step through the linked list of pages, copying the data on each one
* into the buffer. Never copy more than the data's length.
*/
temp = t->bt_psize - BTDATAOFF;
_DBFIT(temp, uint32_t);
plen = (uint32_t)temp;
for (p = *buf;; p = (char *)p + nb, pg = h->nextpg) {
if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
return (RET_ERROR);
nb = MIN(sz, plen);
memmove(p, (char *)(void *)h + BTDATAOFF, nb);
mpool_put(t->bt_mp, h, 0);
if ((sz -= nb) == 0)
break;
}
return (RET_SUCCESS);
}
/*
* BT_META -- write the tree meta data to disk.
*
* Parameters:
* t: tree
*
* Returns:
* RET_ERROR, RET_SUCCESS
*/
static int
bt_meta(BTREE *t)
{
BTMETA m;
void *p;
if ((p = mpool_get(t->bt_mp, P_META, 0)) == NULL)
return (RET_ERROR);
/* Fill in metadata. */
m.magic = BTREEMAGIC;
m.version = BTREEVERSION;
m.psize = t->bt_psize;
m.free = t->bt_free;
m.nrecs = t->bt_nrecs;
m.flags = F_ISSET(t, SAVEMETA);
memmove(p, &m, sizeof(BTMETA));
mpool_put(t->bt_mp, p, MPOOL_DIRTY);
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_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);
}
/*
* __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);
}
/*
* __REC_SEARCH -- Search a btree for a key.
*
* Parameters:
* t: tree to search
* recno: key to find
* op: search operation
*
* Returns:
* EPG for matching record, if any, or the EPG for the location of the
* key, if it were inserted into the tree.
*
* Returns:
* The EPG for matching record, if any, or the EPG for the location
* of the key, if it were inserted into the tree, is entered into
* the bt_cur field of the tree. A pointer to the field is returned.
*/
EPG *
__rec_search(BTREE *t, recno_t recno, enum SRCHOP op)
{
indx_t idx;
PAGE *h;
EPGNO *parent;
RINTERNAL *r;
pgno_t pg;
indx_t top;
recno_t total;
int sverrno;
BT_CLR(t);
for (pg = P_ROOT, total = 0;;) {
if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
goto err;
if (h->flags & P_RLEAF) {
t->bt_cur.page = h;
t->bt_cur.index = recno - total;
return (&t->bt_cur);
}
for (idx = 0, top = NEXTINDEX(h);;) {
r = GETRINTERNAL(h, idx);
if (++idx == top || total + r->nrecs > recno)
break;
total += r->nrecs;
}
BT_PUSH(t, pg, idx - 1);
pg = r->pgno;
switch (op) {
case SDELETE:
--GETRINTERNAL(h, (idx - 1))->nrecs;
mpool_put(t->bt_mp, h, MPOOL_DIRTY);
break;
case SINSERT:
++GETRINTERNAL(h, (idx - 1))->nrecs;
mpool_put(t->bt_mp, h, MPOOL_DIRTY);
break;
case SEARCH:
mpool_put(t->bt_mp, h, 0);
break;
}
}
/* Try and recover the tree. */
err: sverrno = errno;
if (op != SEARCH)
while ((parent = BT_POP(t)) != NULL) {
if ((h = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL)
break;
if (op == SINSERT)
--GETRINTERNAL(h, parent->index)->nrecs;
else
++GETRINTERNAL(h, parent->index)->nrecs;
mpool_put(t->bt_mp, h, MPOOL_DIRTY);
}
errno = sverrno;
return (NULL);
}
DB *
__rec_open(const char *fname, int flags, mode_t mode, const RECNOINFO *openinfo,
int dflags)
{
BTREE *t;
BTREEINFO btopeninfo;
DB *dbp;
PAGE *h;
struct stat sb;
int rfd = -1; /* pacify gcc */
int sverrno;
dbp = NULL;
/* Open the user's file -- if this fails, we're done. */
if (fname != NULL) {
if ((rfd = __dbopen(fname, flags, mode, NULL)) == -1)
return NULL;
}
/* Create a btree in memory (backed by disk). */
if (openinfo) {
if (openinfo->flags & ~(R_FIXEDLEN | R_NOKEY | R_SNAPSHOT))
goto einval;
btopeninfo.flags = 0;
btopeninfo.cachesize = openinfo->cachesize;
btopeninfo.maxkeypage = 0;
btopeninfo.minkeypage = 0;
btopeninfo.psize = openinfo->psize;
btopeninfo.compare = NULL;
btopeninfo.prefix = NULL;
btopeninfo.lorder = openinfo->lorder;
dbp = __bt_open(openinfo->bfname,
O_RDWR, S_IRUSR | S_IWUSR, &btopeninfo, dflags);
} else
dbp = __bt_open(NULL, O_RDWR, S_IRUSR | S_IWUSR, NULL, dflags);
if (dbp == NULL)
goto err;
/*
* Some fields in the tree structure are recno specific. Fill them
* in and make the btree structure look like a recno structure. We
* don't change the bt_ovflsize value, it's close enough and slightly
* bigger.
*/
t = dbp->internal;
if (openinfo) {
if (openinfo->flags & R_FIXEDLEN) {
F_SET(t, R_FIXLEN);
t->bt_reclen = openinfo->reclen;
if (t->bt_reclen == 0)
goto einval;
}
t->bt_bval = openinfo->bval;
} else
t->bt_bval = '\n';
F_SET(t, R_RECNO);
if (fname == NULL)
F_SET(t, R_EOF | R_INMEM);
else
t->bt_rfd = rfd;
if (fname != NULL) {
/*
* In 4.4BSD, stat(2) returns true for ISSOCK on pipes.
* Unfortunately, that's not portable, so we use lseek
* and check the errno values.
*/
errno = 0;
if (lseek(rfd, (off_t)0, SEEK_CUR) == -1 && errno == ESPIPE) {
switch (flags & O_ACCMODE) {
case O_RDONLY:
F_SET(t, R_RDONLY);
break;
default:
goto einval;
}
slow: if ((t->bt_rfp = fdopen(rfd, "r")) == NULL)
goto err;
F_SET(t, R_CLOSEFP);
t->bt_irec =
F_ISSET(t, R_FIXLEN) ? __rec_fpipe : __rec_vpipe;
} else {
switch (flags & O_ACCMODE) {
case O_RDONLY:
F_SET(t, R_RDONLY);
break;
case O_RDWR:
break;
default:
goto einval;
}
if (fstat(rfd, &sb))
goto err;
/*
* Kluge -- we'd like to test to see if the file is too
* big to mmap. Since, we don't know what size or type
* off_t's or size_t's are, what the largest unsigned
* integral type is, or what random insanity the local
* C compiler will perpetrate, doing the comparison in
* a portable way is flatly impossible. Hope that mmap
* fails if the file is too large.
*/
if (sb.st_size == 0)
F_SET(t, R_EOF);
else {
#ifdef MMAP_NOT_AVAILABLE
/*
* XXX
* Mmap doesn't work correctly on many current
* systems. In particular, it can fail subtly,
* with cache coherency problems. Don't use it
* for now.
*/
t->bt_msize = sb.st_size;
if ((t->bt_smap = mmap(NULL, t->bt_msize,
PROT_READ, MAP_FILE | MAP_PRIVATE, rfd,
(off_t)0)) == (caddr_t)-1)
goto slow;
t->bt_cmap = t->bt_smap;
t->bt_emap = t->bt_smap + sb.st_size;
t->bt_irec = F_ISSET(t, R_FIXLEN) ?
__rec_fmap : __rec_vmap;
F_SET(t, R_MEMMAPPED);
#else
goto slow;
#endif
}
}
}
/* Use the recno routines. */
dbp->close = __rec_close;
dbp->del = __rec_delete;
dbp->fd = __rec_fd;
dbp->get = __rec_get;
dbp->put = __rec_put;
dbp->seq = __rec_seq;
dbp->sync = __rec_sync;
/* If the root page was created, reset the flags. */
if ((h = mpool_get(t->bt_mp, P_ROOT, 0)) == NULL)
goto err;
if ((h->flags & P_TYPE) == P_BLEAF) {
F_CLR(h, P_TYPE);
F_SET(h, P_RLEAF);
mpool_put(t->bt_mp, h, MPOOL_DIRTY);
} else
mpool_put(t->bt_mp, h, 0);
if (openinfo && openinfo->flags & R_SNAPSHOT &&
!F_ISSET(t, R_EOF | R_INMEM) &&
t->bt_irec(t, MAX_REC_NUMBER) == RET_ERROR)
goto err;
return (dbp);
einval: errno = EINVAL;
err: sverrno = errno;
if (dbp != NULL)
(void)__bt_close(dbp);
if (fname != NULL)
(void)close(rfd);
errno = sverrno;
return (NULL);
}
/*
* __bt_search --
* Search a btree for a key.
*
* Parameters:
* t: tree to search
* key: key to find
* exactp: pointer to exact match flag
*
* Returns:
* The EPG for matching record, if any, or the EPG for the location
* of the key, if it were inserted into the tree, is entered into
* the bt_cur field of the tree. A pointer to the field is returned.
*/
EPG *
__bt_search(BTREE *t, const DBT *key, int *exactp)
{
PAGE *h;
indx_t base, idx, lim;
pgno_t pg;
int cmp;
BT_CLR(t);
for (pg = P_ROOT;;) {
if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
return (NULL);
/* Do a binary search on the current page. */
t->bt_cur.page = h;
for (base = 0, lim = NEXTINDEX(h); lim; lim >>= 1) {
t->bt_cur.index = idx = base + (lim >> 1);
if ((cmp = __bt_cmp(t, key, &t->bt_cur)) == 0) {
if (h->flags & P_BLEAF) {
*exactp = 1;
return (&t->bt_cur);
}
goto next;
}
if (cmp > 0) {
base = idx + 1;
--lim;
}
}
/*
* If it's a leaf page, we're almost done. If no duplicates
* are allowed, or we have an exact match, we're done. Else,
* it's possible that there were matching keys on this page,
* which later deleted, and we're on a page with no matches
* while there are matches on other pages. If at the start or
* end of a page, check the adjacent page.
*/
if (h->flags & P_BLEAF) {
if (!F_ISSET(t, B_NODUPS)) {
if (base == 0 &&
h->prevpg != P_INVALID &&
__bt_sprev(t, h, key, exactp))
return (&t->bt_cur);
if (base == NEXTINDEX(h) &&
h->nextpg != P_INVALID &&
__bt_snext(t, h, key, exactp))
return (&t->bt_cur);
}
*exactp = 0;
t->bt_cur.index = base;
return (&t->bt_cur);
}
/*
* No match found. Base is the smallest index greater than
* key and may be zero or a last + 1 index. If it's non-zero,
* decrement by one, and record the internal page which should
* be a parent page for the key. If a split later occurs, the
* inserted page will be to the right of the saved page.
*/
idx = base ? base - 1 : base;
next: BT_PUSH(t, h->pgno, idx);
pg = GETBINTERNAL(h, idx)->pgno;
mpool_put(t->bt_mp, h, 0);
}
}
/*
* __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_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) {
if ((prevpg = h->prevpg) == 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 != 0) {
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;
/* 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 = NEXTINDEX(h) - 1;
BT_PUSH(t, pgno, idx);
}
mpool_put(t->bt_mp, h, 0);
if ((h = mpool_get(t->bt_mp, prevpg, 0)) == NULL)
return (1);
}
ret: mpool_put(t->bt_mp, h, 0);
return ((*hp = mpool_get(t->bt_mp, c->pg.pgno, 0)) == NULL);
}
/*
* __BT_SPLIT -- Split the tree.
*
* Parameters:
* t: tree
* sp: page to split
* key: key to insert
* data: data to insert
* flags: BIGKEY/BIGDATA flags
* ilen: insert length
* skip: index to leave open
*
* Returns:
* RET_ERROR, RET_SUCCESS
*/
int
__bt_split(BTREE *t, PAGE *sp, const DBT *key, const DBT *data, int flags,
size_t ilen, u_int32_t argskip)
{
BINTERNAL *bi;
BLEAF *bl, *tbl;
DBT a, b;
EPGNO *parent;
PAGE *h, *l, *r, *lchild, *rchild;
indx_t nxtindex;
u_int16_t skip;
u_int32_t n, nbytes, nksize;
int parentsplit;
char *dest;
/*
* Split the page into two pages, l and r. The split routines return
* a pointer to the page into which the key should be inserted and with
* skip set to the offset which should be used. Additionally, l and r
* are pinned.
*/
skip = argskip;
h = sp->pgno == P_ROOT ?
bt_root(t, sp, &l, &r, &skip, ilen) :
bt_page(t, sp, &l, &r, &skip, ilen);
if (h == NULL)
return (RET_ERROR);
/*
* Insert the new key/data pair into the leaf page. (Key inserts
* always cause a leaf page to split first.)
*/
h->linp[skip] = h->upper -= ilen;
dest = (char *)h + h->upper;
if (F_ISSET(t, R_RECNO))
WR_RLEAF(dest, data, flags)
else
WR_BLEAF(dest, key, data, flags)
/* If the root page was split, make it look right. */
if (sp->pgno == P_ROOT &&
(F_ISSET(t, R_RECNO) ?
bt_rroot(t, sp, l, r) : bt_broot(t, sp, l, r)) == RET_ERROR)
goto err2;
/*
* Now we walk the parent page stack -- a LIFO stack of the pages that
* were traversed when we searched for the page that split. 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 split a page, so we
* have to insert a new key into the parent page.
*
* If the insert into the parent page causes it to split, may have to
* continue splitting all the way up the tree. We stop if the root
* splits or the page inserted into didn't have to split to hold the
* new key. Some algorithms replace the key for the old page as well
* as the new page. We don't, as there's no reason to believe that the
* first key on the old page is any better than the key we have, and,
* in the case of a key being placed at index 0 causing the split, the
* key is unavailable.
*
* There are a maximum of 5 pages pinned at any time. We keep the left
* and right pages pinned while working on the parent. The 5 are the
* two children, left parent and right parent (when the parent splits)
* and the root page or the overflow key page when calling bt_preserve.
* This code must make sure that all pins are released other than the
* root page or overflow page which is unlocked elsewhere.
*/
while ((parent = BT_POP(t)) != NULL) {
lchild = l;
rchild = r;
/* Get the parent page. */
if ((h = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL)
goto err2;
/*
* The new key goes ONE AFTER the index, because the split
* was to the right.
*/
skip = parent->index + 1;
/*
* Calculate the space needed on the parent page.
*
* Prefix trees: space hack when inserting into BINTERNAL
* pages. Retain only what's needed to distinguish between
* the new entry and the LAST entry on the page to its left.
* If the keys compare equal, retain the entire key. Note,
* we don't touch overflow keys, and the entire key must be
* retained for the next-to-left most key on the leftmost
* page of each level, or the search will fail. Applicable
* ONLY to internal pages that have leaf pages as children.
* Further reduction of the key between pairs of internal
* pages loses too much information.
*/
switch (rchild->flags & P_TYPE) {
case P_BINTERNAL:
bi = GETBINTERNAL(rchild, 0);
nbytes = NBINTERNAL(bi->ksize);
break;
case P_BLEAF:
bl = GETBLEAF(rchild, 0);
nbytes = NBINTERNAL(bl->ksize);
if (t->bt_pfx && !(bl->flags & P_BIGKEY) &&
(h->prevpg != P_INVALID || skip > 1)) {
tbl = GETBLEAF(lchild, NEXTINDEX(lchild) - 1);
a.size = tbl->ksize;
a.data = tbl->bytes;
b.size = bl->ksize;
b.data = bl->bytes;
nksize = t->bt_pfx(&a, &b);
n = NBINTERNAL(nksize);
if (n < nbytes) {
#ifdef STATISTICS
bt_pfxsaved += nbytes - n;
#endif
nbytes = n;
} else
nksize = 0;
} else
nksize = 0;
break;
case P_RINTERNAL:
case P_RLEAF:
nbytes = NRINTERNAL;
break;
default:
abort();
}
/* Split the parent page if necessary or shift the indices. */
if ((u_int32_t)(h->upper - h->lower) < nbytes + sizeof(indx_t)) {
sp = h;
h = h->pgno == P_ROOT ?
bt_root(t, h, &l, &r, &skip, nbytes) :
bt_page(t, h, &l, &r, &skip, nbytes);
if (h == NULL)
goto err1;
parentsplit = 1;
} else {
if (skip < (nxtindex = NEXTINDEX(h)))
memmove(h->linp + skip + 1, h->linp + skip,
(nxtindex - skip) * sizeof(indx_t));
h->lower += sizeof(indx_t);
parentsplit = 0;
}
/* Insert the key into the parent page. */
switch (rchild->flags & P_TYPE) {
case P_BINTERNAL:
h->linp[skip] = h->upper -= nbytes;
dest = (char *)h + h->linp[skip];
memmove(dest, bi, nbytes);
((BINTERNAL *)dest)->pgno = rchild->pgno;
break;
case P_BLEAF:
h->linp[skip] = h->upper -= nbytes;
dest = (char *)h + h->linp[skip];
WR_BINTERNAL(dest, nksize ? nksize : bl->ksize,
rchild->pgno, bl->flags & P_BIGKEY);
memmove(dest, bl->bytes, nksize ? nksize : bl->ksize);
if (bl->flags & P_BIGKEY) {
pgno_t pgno;
memcpy(&pgno, bl->bytes, sizeof(pgno));
if (bt_preserve(t, pgno) == RET_ERROR)
goto err1;
}
break;
case P_RINTERNAL:
/*
* Update the left page count. If split
* added at index 0, fix the correct page.
*/
if (skip > 0)
dest = (char *)h + h->linp[skip - 1];
else
dest = (char *)l + l->linp[NEXTINDEX(l) - 1];
((RINTERNAL *)dest)->nrecs = rec_total(lchild);
((RINTERNAL *)dest)->pgno = lchild->pgno;
/* Update the right page count. */
h->linp[skip] = h->upper -= nbytes;
dest = (char *)h + h->linp[skip];
((RINTERNAL *)dest)->nrecs = rec_total(rchild);
((RINTERNAL *)dest)->pgno = rchild->pgno;
break;
case P_RLEAF:
/*
* Update the left page count. If split
* added at index 0, fix the correct page.
*/
if (skip > 0)
dest = (char *)h + h->linp[skip - 1];
else
dest = (char *)l + l->linp[NEXTINDEX(l) - 1];
((RINTERNAL *)dest)->nrecs = NEXTINDEX(lchild);
((RINTERNAL *)dest)->pgno = lchild->pgno;
/* Update the right page count. */
h->linp[skip] = h->upper -= nbytes;
dest = (char *)h + h->linp[skip];
((RINTERNAL *)dest)->nrecs = NEXTINDEX(rchild);
((RINTERNAL *)dest)->pgno = rchild->pgno;
break;
default:
abort();
}
/* Unpin the held pages. */
if (!parentsplit) {
mpool_put(t->bt_mp, h, MPOOL_DIRTY);
break;
}
/* If the root page was split, make it look right. */
if (sp->pgno == P_ROOT &&
(F_ISSET(t, R_RECNO) ?
bt_rroot(t, sp, l, r) : bt_broot(t, sp, l, r)) == RET_ERROR)
goto err1;
mpool_put(t->bt_mp, lchild, MPOOL_DIRTY);
mpool_put(t->bt_mp, rchild, MPOOL_DIRTY);
}
/* Unpin the held pages. */
mpool_put(t->bt_mp, l, MPOOL_DIRTY);
mpool_put(t->bt_mp, r, MPOOL_DIRTY);
/* Clear any pages left on the stack. */
return (RET_SUCCESS);
/*
* If something fails in the above loop we were already walking back
* up the tree and the tree is now inconsistent. Nothing much we can
* do about it but release any memory we're holding.
*/
err1: mpool_put(t->bt_mp, lchild, MPOOL_DIRTY);
mpool_put(t->bt_mp, rchild, MPOOL_DIRTY);
err2: mpool_put(t->bt_mp, l, 0);
mpool_put(t->bt_mp, r, 0);
__dbpanic(t->bt_dbp);
return (RET_ERROR);
}
/*
* BT_PAGE -- Split a non-root page of a btree.
*
* Parameters:
* t: tree
* h: root page
* lp: pointer to left page pointer
* rp: pointer to right page pointer
* skip: pointer to index to leave open
* ilen: insert length
*
* Returns:
* Pointer to page in which to insert or NULL on error.
*/
static PAGE *
bt_page(BTREE *t, PAGE *h, PAGE **lp, PAGE **rp, indx_t *skip, size_t ilen)
{
PAGE *l, *r, *tp;
pgno_t npg;
#ifdef STATISTICS
++bt_split;
#endif
/* Put the new right page for the split into place. */
if ((r = __bt_new(t, &npg)) == NULL)
return (NULL);
r->pgno = npg;
r->lower = BTDATAOFF;
r->upper = t->bt_psize;
r->nextpg = h->nextpg;
r->prevpg = h->pgno;
r->flags = h->flags & P_TYPE;
/*
* If we're splitting the last page on a level because we're appending
* a key to it (skip is NEXTINDEX()), it's likely that the data is
* sorted. Adding an empty page on the side of the level is less work
* and can push the fill factor much higher than normal. If we're
* wrong it's no big deal, we'll just do the split the right way next
* time. It may look like it's equally easy to do a similar hack for
* reverse sorted data, that is, split the tree left, but it's not.
* Don't even try.
*/
if (h->nextpg == P_INVALID && *skip == NEXTINDEX(h)) {
#ifdef STATISTICS
++bt_sortsplit;
#endif
h->nextpg = r->pgno;
r->lower = BTDATAOFF + sizeof(indx_t);
*skip = 0;
*lp = h;
*rp = r;
return (r);
}
/* Put the new left page for the split into place. */
if ((l = (PAGE *)calloc(1, t->bt_psize)) == NULL) {
mpool_put(t->bt_mp, r, 0);
return (NULL);
}
l->pgno = h->pgno;
l->nextpg = r->pgno;
l->prevpg = h->prevpg;
l->lower = BTDATAOFF;
l->upper = t->bt_psize;
l->flags = h->flags & P_TYPE;
/* Fix up the previous pointer of the page after the split page. */
if (h->nextpg != P_INVALID) {
if ((tp = mpool_get(t->bt_mp, h->nextpg, 0)) == NULL) {
free(l);
/* XXX mpool_free(t->bt_mp, r->pgno); */
return (NULL);
}
tp->prevpg = r->pgno;
mpool_put(t->bt_mp, tp, MPOOL_DIRTY);
}
/*
* Split right. The key/data pairs aren't sorted in the btree page so
* it's simpler to copy the data from the split page onto two new pages
* instead of copying half the data to the right page and compacting
* the left page in place. Since the left page can't change, we have
* to swap the original and the allocated left page after the split.
*/
tp = bt_psplit(t, h, l, r, skip, ilen);
/* Move the new left page onto the old left page. */
memmove(h, l, t->bt_psize);
if (tp == l)
tp = h;
free(l);
*lp = h;
*rp = r;
return (tp);
}
/*
* __bt_first --
* Find the first entry.
*
* Parameters:
* t: the tree
* key: the key
* erval: return EPG
* exactp: pointer to exact match flag
*
* Returns:
* The first entry in the tree greater than or equal to key,
* or RET_SPECIAL if no such key exists.
*/
static int
__bt_first(BTREE *t, const DBT *key, EPG *erval, int *exactp)
{
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 (0);
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)
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_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_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));
}
/*
* BT_STAT -- Gather/print the tree statistics
*
* Parameters:
* dbp: pointer to the DB
*/
void
__bt_stat(DB *dbp)
{
extern u_long bt_cache_hit, bt_cache_miss, bt_pfxsaved, bt_rootsplit;
extern u_long bt_sortsplit, bt_split;
BTREE *t;
PAGE *h;
pgno_t i, pcont, pinternal, pleaf;
u_long ifree, lfree, nkeys;
int levels;
t = dbp->internal;
pcont = pinternal = pleaf = 0;
nkeys = ifree = lfree = 0;
for (i = P_ROOT;
(h = mpool_get(t->bt_mp, i, MPOOL_IGNOREPIN)) != NULL; ++i)
switch (h->flags & P_TYPE) {
case P_BINTERNAL:
case P_RINTERNAL:
++pinternal;
ifree += h->upper - h->lower;
break;
case P_BLEAF:
case P_RLEAF:
++pleaf;
lfree += h->upper - h->lower;
nkeys += NEXTINDEX(h);
break;
case P_OVERFLOW:
++pcont;
break;
}
/* Count the levels of the tree. */
for (i = P_ROOT, levels = 0 ;; ++levels) {
h = mpool_get(t->bt_mp, i, MPOOL_IGNOREPIN);
if (h->flags & (P_BLEAF|P_RLEAF)) {
if (levels == 0)
levels = 1;
break;
}
i = F_ISSET(t, R_RECNO) ?
GETRINTERNAL(h, 0)->pgno :
GETBINTERNAL(h, 0)->pgno;
}
(void)fprintf(stderr, "%d level%s with %lu keys",
levels, levels == 1 ? "" : "s", nkeys);
if (F_ISSET(t, R_RECNO))
(void)fprintf(stderr, " (%u header count)", t->bt_nrecs);
(void)fprintf(stderr,
"\n%u pages (leaf %u, internal %u, overflow %u)\n",
pinternal + pleaf + pcont, pleaf, pinternal, pcont);
(void)fprintf(stderr, "%lu cache hits, %lu cache misses\n",
bt_cache_hit, bt_cache_miss);
(void)fprintf(stderr, "%lu splits (%lu root splits, %lu sort splits)\n",
bt_split, bt_rootsplit, bt_sortsplit);
pleaf *= t->bt_psize - BTDATAOFF;
if (pleaf)
(void)fprintf(stderr,
"%.0f%% leaf fill (%lu bytes used, %lu bytes free)\n",
((double)(pleaf - lfree) / pleaf) * 100,
pleaf - lfree, lfree);
pinternal *= t->bt_psize - BTDATAOFF;
if (pinternal)
(void)fprintf(stderr,
"%.0f%% internal fill (%lu bytes used, %lu bytes free\n",
((double)(pinternal - ifree) / pinternal) * 100,
pinternal - ifree, ifree);
if (bt_pfxsaved)
(void)fprintf(stderr, "prefix checking removed %lu bytes.\n",
bt_pfxsaved);
}
