/*
* __cursor_fix_prev --
* Move to the previous, fixed-length column-store item.
*/
static inline int
__cursor_fix_prev(WT_CURSOR_BTREE *cbt, bool newpage)
{
WT_BTREE *btree;
WT_ITEM *val;
WT_PAGE *page;
WT_SESSION_IMPL *session;
WT_UPDATE *upd;
session = (WT_SESSION_IMPL *)cbt->iface.session;
page = cbt->ref->page;
btree = S2BT(session);
val = &cbt->iface.value;
/* Initialize for each new page. */
if (newpage) {
cbt->last_standard_recno = __col_fix_last_recno(page);
if (cbt->last_standard_recno == 0)
return (WT_NOTFOUND);
__cursor_set_recno(cbt, cbt->last_standard_recno);
goto new_page;
}
/* Move to the previous entry and return the item. */
if (cbt->recno == page->pg_fix_recno)
return (WT_NOTFOUND);
__cursor_set_recno(cbt, cbt->recno - 1);
new_page:
/* Check any insert list for a matching record. */
cbt->ins_head = WT_COL_UPDATE_SINGLE(page);
cbt->ins = __col_insert_search(
cbt->ins_head, cbt->ins_stack, cbt->next_stack, cbt->recno);
if (cbt->ins != NULL && cbt->recno != WT_INSERT_RECNO(cbt->ins))
cbt->ins = NULL;
upd = cbt->ins == NULL ? NULL : __wt_txn_read(session, cbt->ins->upd);
if (upd == NULL) {
cbt->v = __bit_getv_recno(page, cbt->recno, btree->bitcnt);
val->data = &cbt->v;
} else
val->data = WT_UPDATE_DATA(upd);
val->size = 1;
return (0);
}
/*
* __cursor_skip_prev --
* Move back one position in a skip list stack (aka "finger").
*/
static inline int
__cursor_skip_prev(WT_CURSOR_BTREE *cbt)
{
WT_INSERT *current, *ins;
WT_ITEM key;
WT_SESSION_IMPL *session;
int i;
session = (WT_SESSION_IMPL *)cbt->iface.session;
restart:
/*
* If the search stack does not point at the current item, fill it in
* with a search.
*/
while ((current = cbt->ins) != PREV_INS(cbt, 0)) {
if (cbt->btree->type == BTREE_ROW) {
key.data = WT_INSERT_KEY(current);
key.size = WT_INSERT_KEY_SIZE(current);
WT_RET(__wt_search_insert(session, cbt, &key));
} else
cbt->ins = __col_insert_search(cbt->ins_head,
cbt->ins_stack, cbt->next_stack,
WT_INSERT_RECNO(current));
}
/*
* Find the first node up the search stack that does not move.
*
* The depth of the current item must be at least this level, since we
* see it in that many levels of the stack.
*
* !!! Watch these loops carefully: they all rely on the value of i,
* and the exit conditions to end up with the right values are
* non-trivial.
*/
ins = NULL; /* -Wconditional-uninitialized */
for (i = 0; i < WT_SKIP_MAXDEPTH - 1; i++)
if ((ins = PREV_INS(cbt, i + 1)) != current)
break;
/*
* Find a starting point for the new search. That is either at the
* non-moving node if we found a valid node, or the beginning of the
* next list down that is not the current node.
*
* Since it is the beginning of a list, and we know the current node is
* has a skip depth at least this high, any node we find must sort
* before the current node.
*/
if (ins == NULL || ins == current)
for (; i >= 0; i--) {
cbt->ins_stack[i] = NULL;
cbt->next_stack[i] = NULL;
ins = cbt->ins_head->head[i];
if (ins != NULL && ins != current)
break;
}
/* Walk any remaining levels until just before the current node. */
while (i >= 0) {
/*
* If we get to the end of a list without finding the current
* item, we must have raced with an insert. Restart the search.
*/
if (ins == NULL) {
cbt->ins_stack[0] = NULL;
cbt->next_stack[0] = NULL;
goto restart;
}
if (ins->next[i] != current) /* Stay at this level */
ins = ins->next[i];
else { /* Drop down a level */
cbt->ins_stack[i] = &ins->next[i];
cbt->next_stack[i] = ins->next[i];
--i;
}
}
/* If we found a previous node, the next one must be current. */
if (cbt->ins_stack[0] != NULL && *cbt->ins_stack[0] != current)
goto restart;
cbt->ins = PREV_INS(cbt, 0);
return (0);
}
/*
* __wt_col_append_serial_func --
* Server function to append an WT_INSERT entry to the tree.
*/
int
__wt_col_append_serial_func(WT_SESSION_IMPL *session, void *args)
{
WT_BTREE *btree;
WT_INSERT *ins, *new_ins, ***ins_stack, **next_stack;
WT_INSERT_HEAD *inshead, **insheadp, **new_inslist, *new_inshead;
WT_PAGE *page;
uint64_t recno;
uint32_t write_gen;
u_int i, skipdepth;
btree = S2BT(session);
__wt_col_append_unpack(args,
&page, &write_gen, &insheadp, &ins_stack, &next_stack,
&new_inslist, &new_inshead, &new_ins, &skipdepth);
/* Check the page's write-generation. */
WT_RET(__wt_page_write_gen_check(session, page, write_gen));
if ((inshead = *insheadp) == NULL)
inshead = new_inshead;
/*
* If the application specified a record number, there's a race: the
* application may have searched for the record, not found it, then
* called into the append code, and another thread might have added
* the record. Fortunately, we're in the right place because if the
* record didn't exist at some point, it can only have been created
* on this list. Search for the record, if specified.
*/
if ((recno = WT_INSERT_RECNO(new_ins)) == 0)
recno = WT_INSERT_RECNO(new_ins) = ++btree->last_recno;
ins = __col_insert_search(inshead, ins_stack, next_stack, recno);
/* If we find the record number, there's been a race. */
if (ins != NULL && WT_INSERT_RECNO(ins) == recno)
WT_RET(WT_RESTART);
/*
* Publish: First, point the new WT_INSERT item's skiplist references
* to the next elements in the insert list, then flush memory. Second,
* update the skiplist elements that reference the new WT_INSERT item,
* this ensures the list is never inconsistent.
*/
for (i = 0; i < skipdepth; i++)
new_ins->next[i] = *ins_stack[i];
WT_WRITE_BARRIER();
for (i = 0; i < skipdepth; i++) {
if (inshead->tail[i] == NULL ||
ins_stack[i] == &inshead->tail[i]->next[i])
inshead->tail[i] = new_ins;
*ins_stack[i] = new_ins;
}
__wt_col_append_new_ins_taken(args);
/*
* If the insert head does not yet have an insert list, our caller
* passed us one.
*
* NOTE: it is important to do this after the item has been added to
* the list. Code can assume that if the list is set, it is non-empty.
*/
if (*insheadp == NULL) {
WT_PUBLISH(*insheadp, new_inshead);
__wt_col_append_new_inshead_taken(args);
}
/*
* If the page does not yet have an insert array, our caller passed
* us one.
*
* NOTE: it is important to do this after publishing the list entry.
* Code can assume that if the array is set, it is non-empty.
*/
if (page->modify->append == NULL) {
page->modify->append = new_inslist;
__wt_col_append_new_inslist_taken(args);
}
/*
* If we don't find the record, check to see if we extended the file,
* and update the last record number.
*/
if (recno > btree->last_recno)
btree->last_recno = recno;
__wt_page_and_tree_modify_set(session, page);
return (0);
}
/*
* __wt_col_modify --
* Column-store delete, insert, and update.
*/
int
__wt_col_modify(WT_SESSION_IMPL *session, WT_CURSOR_BTREE *cbt,
uint64_t recno, const WT_ITEM *value,
WT_UPDATE *upd_arg, u_int modify_type, bool exclusive)
{
static const WT_ITEM col_fix_remove = { "", 1, NULL, 0, 0 };
WT_BTREE *btree;
WT_DECL_RET;
WT_INSERT *ins;
WT_INSERT_HEAD *ins_head, **ins_headp;
WT_PAGE *page;
WT_PAGE_MODIFY *mod;
WT_UPDATE *old_upd, *upd;
size_t ins_size, upd_size;
u_int i, skipdepth;
bool append, logged;
btree = cbt->btree;
ins = NULL;
page = cbt->ref->page;
upd = upd_arg;
append = logged = false;
if (upd_arg == NULL) {
if (modify_type == WT_UPDATE_RESERVE ||
modify_type == WT_UPDATE_TOMBSTONE) {
/*
* Fixed-size column-store doesn't have on-page deleted
* values, it's a nul byte.
*/
if (modify_type == WT_UPDATE_TOMBSTONE &&
btree->type == BTREE_COL_FIX) {
modify_type = WT_UPDATE_STANDARD;
value = &col_fix_remove;
}
}
/*
* There's a chance the application specified a record past the
* last record on the page. If that's the case and we're
* inserting a new WT_INSERT/WT_UPDATE pair, it goes on the
* append list, not the update list. Also, an out-of-band recno
* implies an append operation, we're allocating a new row.
* Ignore any information obtained from the search.
*/
WT_ASSERT(session, recno != WT_RECNO_OOB || cbt->compare != 0);
if (cbt->compare != 0 &&
(recno == WT_RECNO_OOB ||
recno > (btree->type == BTREE_COL_VAR ?
__col_var_last_recno(cbt->ref) :
__col_fix_last_recno(cbt->ref)))) {
append = true;
cbt->ins = NULL;
cbt->ins_head = NULL;
}
}
/* We're going to modify the page, we should have loaded history. */
WT_ASSERT(session, cbt->ref->state != WT_REF_LIMBO);
/* If we don't yet have a modify structure, we'll need one. */
WT_RET(__wt_page_modify_init(session, page));
mod = page->modify;
/*
* If modifying a record not previously modified, but which is in the
* same update slot as a previously modified record, cursor.ins will
* not be set because there's no list of update records for this recno,
* but cursor.ins_head will be set to point to the correct update slot.
* Acquire the necessary insert information, then create a new update
* entry and link it into the existing list. We get here if a page has
* a single cell representing multiple records (the records have the
* same value), and then a record in the cell is updated or removed,
* creating the update list for the cell, and then a cursor iterates
* into that same cell to update/remove a different record. We find the
* correct slot in the update array, but we don't find an update list
* (because it doesn't exist), and don't have the information we need
* to do the insert. Normally, we wouldn't care (we could fail and do
* a search for the record which would configure everything for the
* insert), but range truncation does this pattern for every record in
* the cell, and the performance is terrible. For that reason, catch it
* here.
*/
if (cbt->ins == NULL && cbt->ins_head != NULL) {
cbt->ins = __col_insert_search(
cbt->ins_head, cbt->ins_stack, cbt->next_stack, recno);
if (cbt->ins != NULL) {
if (WT_INSERT_RECNO(cbt->ins) == recno)
cbt->compare = 0;
else {
/*
* The test below is for cursor.compare set to 0
* and cursor.ins set: cursor.compare wasn't set
* by the search we just did, and has an unknown
* value. Clear cursor.ins to avoid the test.
*/
cbt->ins = NULL;
}
}
}
/*
* Delete, insert or update a column-store entry.
*
* If modifying a previously modified record, cursor.ins will be set to
* point to the correct update list. Create a new update entry and link
* it into the existing list.
*
* Else, allocate an insert array as necessary, build an insert/update
* structure pair, and link it into place.
*/
if (cbt->compare == 0 && cbt->ins != NULL) {
/*
* If we are restoring updates that couldn't be evicted, the
* key must not exist on the new page.
*/
WT_ASSERT(session, upd_arg == NULL);
/* Make sure the update can proceed. */
WT_ERR(__wt_txn_update_check(session, old_upd = cbt->ins->upd));
/* Allocate a WT_UPDATE structure and transaction ID. */
WT_ERR(__wt_update_alloc(session,
value, &upd, &upd_size, modify_type));
WT_ERR(__wt_txn_modify(session, upd));
logged = true;
/* Avoid a data copy in WT_CURSOR.update. */
cbt->modify_update = upd;
/*
* Point the new WT_UPDATE item to the next element in the list.
* If we get it right, the serialization function lock acts as
* our memory barrier to flush this write.
*/
upd->next = old_upd;
/* Serialize the update. */
WT_ERR(__wt_update_serial(
session, page, &cbt->ins->upd, &upd, upd_size, false));
} else {
/* Allocate the append/update list reference as necessary. */
if (append) {
WT_PAGE_ALLOC_AND_SWAP(session,
page, mod->mod_col_append, ins_headp, 1);
ins_headp = &mod->mod_col_append[0];
} else if (page->type == WT_PAGE_COL_FIX) {
WT_PAGE_ALLOC_AND_SWAP(session,
page, mod->mod_col_update, ins_headp, 1);
ins_headp = &mod->mod_col_update[0];
} else {
WT_PAGE_ALLOC_AND_SWAP(session, page,
mod->mod_col_update, ins_headp, page->entries);
ins_headp = &mod->mod_col_update[cbt->slot];
}
/* Allocate the WT_INSERT_HEAD structure as necessary. */
WT_PAGE_ALLOC_AND_SWAP(session, page, *ins_headp, ins_head, 1);
ins_head = *ins_headp;
/* Choose a skiplist depth for this insert. */
skipdepth = __wt_skip_choose_depth(session);
/*
* Allocate a WT_INSERT/WT_UPDATE pair and transaction ID, and
* update the cursor to reference it (the WT_INSERT_HEAD might
* be allocated, the WT_INSERT was allocated).
*/
WT_ERR(__col_insert_alloc(
session, recno, skipdepth, &ins, &ins_size));
cbt->ins_head = ins_head;
cbt->ins = ins;
/*
* Check for insert split and checkpoint races in column-store:
* it's easy (as opposed to in row-store) and a difficult bug to
* otherwise diagnose.
*/
WT_ASSERT(session, mod->mod_col_split_recno == WT_RECNO_OOB ||
(recno != WT_RECNO_OOB &&
mod->mod_col_split_recno > recno));
if (upd_arg == NULL) {
WT_ERR(__wt_update_alloc(session,
value, &upd, &upd_size, modify_type));
WT_ERR(__wt_txn_modify(session, upd));
logged = true;
/* Avoid a data copy in WT_CURSOR.update. */
cbt->modify_update = upd;
} else
upd_size = __wt_update_list_memsize(upd);
ins->upd = upd;
ins_size += upd_size;
/*
* If there was no insert list during the search, or there was
* no search because the record number has not been allocated
* yet, the cursor's information cannot be correct, search
* couldn't have initialized it.
*
* Otherwise, point the new WT_INSERT item's skiplist to the
* next elements in the insert list (which we will check are
* still valid inside the serialization function).
*
* The serial mutex acts as our memory barrier to flush these
* writes before inserting them into the list.
*/
if (cbt->ins_stack[0] == NULL || recno == WT_RECNO_OOB)
for (i = 0; i < skipdepth; i++) {
cbt->ins_stack[i] = &ins_head->head[i];
ins->next[i] = cbt->next_stack[i] = NULL;
}
else
for (i = 0; i < skipdepth; i++)
ins->next[i] = cbt->next_stack[i];
/* Append or insert the WT_INSERT structure. */
if (append)
WT_ERR(__wt_col_append_serial(
session, page, cbt->ins_head, cbt->ins_stack,
&ins, ins_size, &cbt->recno, skipdepth, exclusive));
else
WT_ERR(__wt_insert_serial(
session, page, cbt->ins_head, cbt->ins_stack,
&ins, ins_size, skipdepth, exclusive));
}
/* If the update was successful, add it to the in-memory log. */
if (logged && modify_type != WT_UPDATE_RESERVE) {
WT_ERR(__wt_txn_log_op(session, cbt));
/*
* In case of append, the recno (key) for the value is assigned
* now. Set the recno in the transaction operation to be used
* incase this transaction is prepared to retrieve the update
* corresponding to this operation.
*/
__wt_txn_op_set_recno(session, cbt->recno);
}
if (0) {
err: /*
* Remove the update from the current transaction, so we don't
* try to modify it on rollback.
*/
if (logged)
__wt_txn_unmodify(session);
__wt_free(session, ins);
if (upd_arg == NULL)
__wt_free(session, upd);
}
return (ret);
}
