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/*-
* Copyright (c) 2014-2015 MongoDB, Inc.
* Copyright (c) 2008-2014 WiredTiger, Inc.
* All rights reserved.
*
* See the file LICENSE for redistribution information.
*/
/*
* __col_insert_search_match --
* Search an column-store insert list for an exact match.
*/
static inline WT_INSERT *
__col_insert_search_match(WT_INSERT_HEAD *inshead, uint64_t recno)
{
WT_INSERT **insp, *ret_ins;
uint64_t ins_recno;
int cmp, i;
/* If there's no insert chain to search, we're done. */
if ((ret_ins = WT_SKIP_LAST(inshead)) == NULL)
return (NULL);
/* Fast path the check for values at the end of the skiplist. */
if (recno > WT_INSERT_RECNO(ret_ins))
return (NULL);
else if (recno == WT_INSERT_RECNO(ret_ins))
return (ret_ins);
/*
* The insert list is a skip list: start at the highest skip level, then
* go as far as possible at each level before stepping down to the next.
*/
for (i = WT_SKIP_MAXDEPTH - 1, insp = &inshead->head[i]; i >= 0; ) {
if (*insp == NULL) {
--i;
--insp;
continue;
}
ins_recno = WT_INSERT_RECNO(*insp);
cmp = (recno == ins_recno) ? 0 : (recno < ins_recno) ? -1 : 1;
if (cmp == 0) /* Exact match: return */
return (*insp);
else if (cmp > 0) /* Keep going at this level */
insp = &(*insp)->next[i];
else { /* Drop down a level */
--i;
--insp;
}
}
return (NULL);
}
/*
* __col_insert_search --
* Search a column-store insert list, creating a skiplist stack as we go.
*/
static inline WT_INSERT *
__col_insert_search(WT_INSERT_HEAD *inshead,
WT_INSERT ***ins_stack, WT_INSERT **next_stack, uint64_t recno)
{
WT_INSERT **insp, *ret_ins;
uint64_t ins_recno;
int cmp, i;
/* If there's no insert chain to search, we're done. */
if ((ret_ins = WT_SKIP_LAST(inshead)) == NULL)
return (NULL);
/* Fast path appends. */
if (recno >= WT_INSERT_RECNO(ret_ins)) {
for (i = 0; i < WT_SKIP_MAXDEPTH; i++) {
ins_stack[i] = (i == 0) ? &ret_ins->next[0] :
(inshead->tail[i] != NULL) ?
&inshead->tail[i]->next[i] : &inshead->head[i];
next_stack[i] = NULL;
}
return (ret_ins);
}
/*
* The insert list is a skip list: start at the highest skip level, then
* go as far as possible at each level before stepping down to the next.
*/
for (i = WT_SKIP_MAXDEPTH - 1, insp = &inshead->head[i]; i >= 0; ) {
if ((ret_ins = *insp) == NULL) {
next_stack[i] = NULL;
ins_stack[i--] = insp--;
continue;
}
ins_recno = WT_INSERT_RECNO(ret_ins);
cmp = (recno == ins_recno) ? 0 : (recno < ins_recno) ? -1 : 1;
if (cmp > 0) /* Keep going at this level */
insp = &ret_ins->next[i];
else if (cmp == 0) /* Exact match: return */
for (; i >= 0; i--) {
next_stack[i] = ret_ins->next[i];
ins_stack[i] = &ret_ins->next[i];
}
else { /* Drop down a level */
next_stack[i] = ret_ins;
ins_stack[i--] = insp--;
}
}
return (ret_ins);
}
/*
* __col_var_last_recno --
* Return the last record number for a variable-length column-store page.
*/
static inline uint64_t
__col_var_last_recno(WT_PAGE *page)
{
WT_COL_RLE *repeat;
/*
* If there's an append list (the last page), then there may be more
* records on the page. This function ignores those records, so our
* callers have to handle that explicitly, if they care.
*/
if (page->pg_var_nrepeats == 0)
return (page->pg_var_entries == 0 ? 0 :
page->pg_var_recno + (page->pg_var_entries - 1));
repeat = &page->pg_var_repeats[page->pg_var_nrepeats - 1];
return ((repeat->recno + repeat->rle) - 1 +
(page->pg_var_entries - (repeat->indx + 1)));
}
/*
* __col_fix_last_recno --
* Return the last record number for a fixed-length column-store page.
*/
static inline uint64_t
__col_fix_last_recno(WT_PAGE *page)
{
/*
* If there's an append list (the last page), then there may be more
* records on the page. This function ignores those records, so our
* callers have to handle that explicitly, if they care.
*/
return (page->pg_fix_entries == 0 ? 0 :
page->pg_fix_recno + (page->pg_fix_entries - 1));
}
/*
* __col_var_search --
* Search a variable-length column-store page for a record.
*/
static inline WT_COL *
__col_var_search(WT_PAGE *page, uint64_t recno)
{
WT_COL_RLE *repeat;
uint64_t start_recno;
uint32_t base, indx, limit, start_indx;
/*
* Find the matching slot.
*
* This is done in two stages: first, we do a binary search among any
* repeating records to find largest repeating less than the search key.
* Once there, we can do a simple offset calculation to find the correct
* slot for this record number, because we know any intervening records
* have repeat counts of 1.
*/
for (base = 0, limit = page->pg_var_nrepeats; limit != 0; limit >>= 1) {
indx = base + (limit >> 1);
repeat = page->pg_var_repeats + indx;
if (recno >= repeat->recno &&
recno < repeat->recno + repeat->rle)
return (page->pg_var_d + repeat->indx);
if (recno < repeat->recno)
continue;
base = indx + 1;
--limit;
}
/*
* We didn't find an exact match, move forward from the largest repeat
* less than the search key.
*/
if (base == 0) {
start_indx = 0;
start_recno = page->pg_var_recno;
} else {
repeat = page->pg_var_repeats + (base - 1);
start_indx = repeat->indx + 1;
start_recno = repeat->recno + repeat->rle;
}
if (recno >= start_recno + (page->pg_var_entries - start_indx))
return (NULL);
return (page->pg_var_d + start_indx + (uint32_t)(recno - start_recno));
}
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