/*
* __txn_abort_newer_row_leaf --
* Abort updates on a row leaf page with timestamps newer than the
* rollback timestamp.
*/
static void
__txn_abort_newer_row_leaf(
WT_SESSION_IMPL *session, WT_PAGE *page, wt_timestamp_t *rollback_timestamp)
{
WT_INSERT_HEAD *insert;
WT_ROW *rip;
WT_UPDATE *upd;
uint32_t i;
/*
* Review the insert list for keys before the first entry on the disk
* page.
*/
if ((insert = WT_ROW_INSERT_SMALLEST(page)) != NULL)
__txn_abort_newer_row_skip(
session, insert, rollback_timestamp);
/*
* Review updates that belong to keys that are on the disk image,
* as well as for keys inserted since the page was read from disk.
*/
WT_ROW_FOREACH(page, rip, i) {
if ((upd = WT_ROW_UPDATE(page, rip)) != NULL)
__txn_abort_newer_update(
session, upd, rollback_timestamp);
if ((insert = WT_ROW_INSERT(page, rip)) != NULL)
__txn_abort_newer_row_skip(
session, insert, rollback_timestamp);
}
}
/*
* __wt_page_obsolete --
* Discard all obsolete updates on a row-store leaf page.
*/
void
__wt_row_leaf_obsolete(WT_SESSION_IMPL *session, WT_PAGE *page)
{
WT_INSERT *ins;
WT_ROW *rip;
WT_UPDATE *upd;
uint32_t i;
/* For entries before the first on-page record... */
WT_SKIP_FOREACH(ins, WT_ROW_INSERT_SMALLEST(page))
if ((upd =
__wt_update_obsolete_check(session, ins->upd)) != NULL)
__wt_update_obsolete_free(session, page, upd);
/* For each entry on the page... */
WT_ROW_FOREACH(page, rip, i) {
if ((upd = __wt_update_obsolete_check(
session, WT_ROW_UPDATE(page, rip))) != NULL)
__wt_update_obsolete_free(session, page, upd);
WT_SKIP_FOREACH(ins, WT_ROW_INSERT(page, rip))
if ((upd = __wt_update_obsolete_check(
session, ins->upd)) != NULL)
__wt_update_obsolete_free(session, page, upd);
}
}
/*
* __wt_btcur_iterate_setup --
* Initialize a cursor for iteration, usually based on a search.
*/
void
__wt_btcur_iterate_setup(WT_CURSOR_BTREE *cbt, int next)
{
WT_PAGE *page;
WT_UNUSED(next);
/*
* We don't currently have to do any setup when we switch between next
* and prev calls, but I'm sure we will someday -- I'm leaving support
* here for both flags for that reason.
*/
F_SET(cbt, WT_CBT_ITERATE_NEXT | WT_CBT_ITERATE_PREV);
/*
* Clear the count of deleted items on the page.
*/
cbt->page_deleted_count = 0;
/*
* If we don't have a search page, then we're done, we're starting at
* the beginning or end of the tree, not as a result of a search.
*/
if (cbt->ref == NULL)
return;
page = cbt->ref->page;
if (page->type == WT_PAGE_ROW_LEAF) {
/*
* For row-store pages, we need a single item that tells us the
* part of the page we're walking (otherwise switching from next
* to prev and vice-versa is just too complicated), so we map
* the WT_ROW and WT_INSERT_HEAD insert array slots into a
* single name space: slot 1 is the "smallest key insert list",
* slot 2 is WT_ROW[0], slot 3 is WT_INSERT_HEAD[0], and so on.
* This means WT_INSERT lists are odd-numbered slots, and WT_ROW
* array slots are even-numbered slots.
*/
cbt->row_iteration_slot = (cbt->slot + 1) * 2;
if (cbt->ins_head != NULL) {
if (cbt->ins_head == WT_ROW_INSERT_SMALLEST(page))
cbt->row_iteration_slot = 1;
else
cbt->row_iteration_slot += 1;
}
} else {
/*
* For column-store pages, calculate the largest record on the
* page.
*/
cbt->last_standard_recno = page->type == WT_PAGE_COL_VAR ?
__col_var_last_recno(page) : __col_fix_last_recno(page);
/* If we're traversing the append list, set the reference. */
if (cbt->ins_head != NULL &&
cbt->ins_head == WT_COL_APPEND(page))
F_SET(cbt, WT_CBT_ITERATE_APPEND);
}
}
/*为一个检索操作初始化一个查询的cursor*/
void __wt_btcur_iterate_setup(WT_CURSOR_BTREE* cbt, int next)
{
WT_PAGE *page;
WT_UNUSED(next);
/*
* We don't currently have to do any setup when we switch between next
* and prev calls, but I'm sure we will someday -- I'm leaving support
* here for both flags for that reason.
*/
F_SET(cbt, WT_CBT_ITERATE_NEXT | WT_CBT_ITERATE_PREV);
/*初始化del count计数器，在检索的过程需要统计del count*/
cbt->page_deleted_count = 0;
if (cbt->ref == NULL)
return;
page = cbt->ref->page;
/*行存储叶子节点*/
if (page->type == WT_PAGE_ROW_LEAF){
/*指定iteration slot*/
/*
* For row-store pages, we need a single item that tells us the
* part of the page we're walking (otherwise switching from next
* to prev and vice-versa is just too complicated), so we map
* the WT_ROW and WT_INSERT_HEAD insert array slots into a
* single name space: slot 1 is the "smallest key insert list",
* slot 2 is WT_ROW[0], slot 3 is WT_INSERT_HEAD[0], and so on.
* This means WT_INSERT lists are odd-numbered slots, and WT_ROW
* array slots are even-numbered slots.
*/
cbt->row_iteration_slot = (cbt->slot + 1) * 2;
if (cbt->ins_head != NULL){
if (cbt->ins_head == WT_ROW_INSERT_SMALLEST(page))
cbt->row_iteration_slot = 1;
else
cbt->row_iteration_slot += 1;
}
}
else{ /*column store page, 计算这个page中最大的记录序号*/
cbt->last_standard_recno = page->type == WT_PAGE_COL_VAR ? __col_var_last_recno(page) : __col_fix_last_recno(page);
if (cbt->ins_head != NULL && cbt->ins_head == WT_COL_APPEND(page))
F_SET(cbt, WT_CBT_ITERATE_APPEND);
}
}
/*
* __cursor_row_prev --
* Move to the previous row-store item.
*/
static inline int
__cursor_row_prev(WT_CURSOR_BTREE *cbt, bool newpage)
{
WT_INSERT *ins;
WT_ITEM *key, *val;
WT_PAGE *page;
WT_ROW *rip;
WT_SESSION_IMPL *session;
WT_UPDATE *upd;
session = (WT_SESSION_IMPL *)cbt->iface.session;
page = cbt->ref->page;
key = &cbt->iface.key;
val = &cbt->iface.value;
/*
* For row-store pages, we need a single item that tells us the part
* of the page we're walking (otherwise switching from next to prev
* and vice-versa is just too complicated), so we map the WT_ROW and
* WT_INSERT_HEAD insert array slots into a single name space: slot 1
* is the "smallest key insert list", slot 2 is WT_ROW[0], slot 3 is
* WT_INSERT_HEAD[0], and so on. This means WT_INSERT lists are
* odd-numbered slots, and WT_ROW array slots are even-numbered slots.
*
* New page configuration.
*/
if (newpage) {
/*
* If we haven't instantiated keys on this page, do so, else it
* is a very, very slow traversal.
*/
if (!F_ISSET_ATOMIC(page, WT_PAGE_BUILD_KEYS))
WT_RET(__wt_row_leaf_keys(session, page));
if (page->pg_row_entries == 0)
cbt->ins_head = WT_ROW_INSERT_SMALLEST(page);
else
cbt->ins_head =
WT_ROW_INSERT_SLOT(page, page->pg_row_entries - 1);
cbt->ins = WT_SKIP_LAST(cbt->ins_head);
cbt->row_iteration_slot = page->pg_row_entries * 2 + 1;
goto new_insert;
}
/* Move to the previous entry and return the item. */
for (;;) {
/*
* Continue traversing any insert list. Maintain the reference
* to the current insert element in case we switch to a cursor
* next movement.
*/
if (cbt->ins != NULL)
WT_RET(__cursor_skip_prev(cbt));
new_insert: if ((ins = cbt->ins) != NULL) {
if ((upd = __wt_txn_read(session, ins->upd)) == NULL)
continue;
if (WT_UPDATE_DELETED_ISSET(upd)) {
if (__wt_txn_visible_all(session, upd->txnid))
++cbt->page_deleted_count;
continue;
}
key->data = WT_INSERT_KEY(ins);
key->size = WT_INSERT_KEY_SIZE(ins);
val->data = WT_UPDATE_DATA(upd);
val->size = upd->size;
return (0);
}
/* Check for the beginning of the page. */
if (cbt->row_iteration_slot == 1)
return (WT_NOTFOUND);
--cbt->row_iteration_slot;
/*
* Odd-numbered slots configure as WT_INSERT_HEAD entries,
* even-numbered slots configure as WT_ROW entries.
*/
if (cbt->row_iteration_slot & 0x01) {
cbt->ins_head = cbt->row_iteration_slot == 1 ?
WT_ROW_INSERT_SMALLEST(page) :
WT_ROW_INSERT_SLOT(
page, cbt->row_iteration_slot / 2 - 1);
cbt->ins = WT_SKIP_LAST(cbt->ins_head);
goto new_insert;
}
cbt->ins_head = NULL;
cbt->ins = NULL;
cbt->slot = cbt->row_iteration_slot / 2 - 1;
rip = &page->pg_row_d[cbt->slot];
upd = __wt_txn_read(session, WT_ROW_UPDATE(page, rip));
if (upd != NULL && WT_UPDATE_DELETED_ISSET(upd)) {
if (__wt_txn_visible_all(session, upd->txnid))
++cbt->page_deleted_count;
continue;
}
return (__cursor_row_slot_return(cbt, rip, upd));
}
/* NOTREACHED */
}
/*
* __cursor_row_next --
* Move to the next row-store item.
*/
static inline int
__cursor_row_next(WT_CURSOR_BTREE *cbt, bool newpage)
{
WT_INSERT *ins;
WT_ITEM *key;
WT_PAGE *page;
WT_ROW *rip;
WT_SESSION_IMPL *session;
WT_UPDATE *upd;
session = (WT_SESSION_IMPL *)cbt->iface.session;
page = cbt->ref->page;
key = &cbt->iface.key;
/*
* For row-store pages, we need a single item that tells us the part
* of the page we're walking (otherwise switching from next to prev
* and vice-versa is just too complicated), so we map the WT_ROW and
* WT_INSERT_HEAD insert array slots into a single name space: slot 1
* is the "smallest key insert list", slot 2 is WT_ROW[0], slot 3 is
* WT_INSERT_HEAD[0], and so on. This means WT_INSERT lists are
* odd-numbered slots, and WT_ROW array slots are even-numbered slots.
*
* Initialize for each new page.
*/
if (newpage) {
cbt->ins_head = WT_ROW_INSERT_SMALLEST(page);
cbt->ins = WT_SKIP_FIRST(cbt->ins_head);
cbt->row_iteration_slot = 1;
cbt->rip_saved = NULL;
goto new_insert;
}
/* Move to the next entry and return the item. */
for (;;) {
/*
* Continue traversing any insert list; maintain the insert list
* head reference and entry count in case we switch to a cursor
* previous movement.
*/
if (cbt->ins != NULL)
cbt->ins = WT_SKIP_NEXT(cbt->ins);
new_insert: if ((ins = cbt->ins) != NULL) {
if ((upd = __wt_txn_read(session, ins->upd)) == NULL)
continue;
if (upd->type == WT_UPDATE_DELETED) {
if (__wt_txn_upd_visible_all(session, upd))
++cbt->page_deleted_count;
continue;
}
key->data = WT_INSERT_KEY(ins);
key->size = WT_INSERT_KEY_SIZE(ins);
return (__wt_value_return(session, cbt, upd));
}
/* Check for the end of the page. */
if (cbt->row_iteration_slot >= page->entries * 2 + 1)
return (WT_NOTFOUND);
++cbt->row_iteration_slot;
/*
* Odd-numbered slots configure as WT_INSERT_HEAD entries,
* even-numbered slots configure as WT_ROW entries.
*/
if (cbt->row_iteration_slot & 0x01) {
cbt->ins_head = WT_ROW_INSERT_SLOT(
page, cbt->row_iteration_slot / 2 - 1);
cbt->ins = WT_SKIP_FIRST(cbt->ins_head);
goto new_insert;
}
cbt->ins_head = NULL;
cbt->ins = NULL;
cbt->slot = cbt->row_iteration_slot / 2 - 1;
rip = &page->pg_row[cbt->slot];
upd = __wt_txn_read(session, WT_ROW_UPDATE(page, rip));
if (upd != NULL && upd->type == WT_UPDATE_DELETED) {
if (__wt_txn_upd_visible_all(session, upd))
++cbt->page_deleted_count;
continue;
}
return (__cursor_row_slot_return(cbt, rip, upd));
}
/* NOTREACHED */
}
/*移向行存储的下一个行对象*/
static inline int __cursor_row_next(WT_CURSOR_BTREE* cbt, int newpage)
{
WT_INSERT *ins;
WT_ITEM *key, *val;
WT_PAGE *page;
WT_ROW *rip;
WT_SESSION_IMPL *session;
WT_UPDATE *upd;
session = (WT_SESSION_IMPL *)cbt->iface.session;
page = cbt->ref->page;
key = &cbt->iface.key;
val = &cbt->iface.value;
/*假如是newpage，定位到insert修改队列的头位置*/
if (newpage){
cbt->ins_head = WT_ROW_INSERT_SMALLEST(page);
cbt->ins = WT_SKIP_FIRST(cbt->ins_head);
cbt->row_iteration_slot = 1;
goto new_insert;
}
for (;;){
if (cbt->ins != NULL)
cbt->ins = WT_SKIP_NEXT(cbt->ins);
new_insert:
if ((ins = cbt->ins) != NULL) {
/*事务可见数据读取*/
if ((upd = __wt_txn_read(session, ins->upd)) == NULL)
continue;
/*判断是否删除，如果删除，跳过被删除的对象*/
if (WT_UPDATE_DELETED_ISSET(upd)) {
++cbt->page_deleted_count;
continue;
}
key->data = WT_INSERT_KEY(ins);
key->size = WT_INSERT_KEY_SIZE(ins);
val->data = WT_UPDATE_DATA(upd);
val->size = upd->size;
return 0;
}
/*检索page row entires数组， 到了page的末尾*/
if (cbt->row_iteration_slot >= page->pg_row_entries * 2 + 1)
return (WT_NOTFOUND);
++cbt->row_iteration_slot;
/*
* Odd-numbered slots configure as WT_INSERT_HEAD entries,
* even-numbered slots configure as WT_ROW entries.
*/
if (cbt->row_iteration_slot & 0x01) {
cbt->ins_head = WT_ROW_INSERT_SLOT(page, cbt->row_iteration_slot / 2 - 1);
cbt->ins = WT_SKIP_FIRST(cbt->ins_head);
goto new_insert;
}
cbt->ins_head = NULL;
cbt->ins = NULL;
/*计算定位slot*/
cbt->slot = cbt->row_iteration_slot / 2 - 1;
rip = &page->pg_row_d[cbt->slot];
upd = __wt_txn_read(session, WT_ROW_UPDATE(page, rip));
if (upd != NULL && WT_UPDATE_DELETED_ISSET(upd)) {
++cbt->page_deleted_count;
continue;
}
return __cursor_row_slot_return(cbt, rip, upd);
}
}
