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btr0cur.cc
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btr0cur.cc
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#include "btr0cur.h"
#include "page0page.h"
#include "rem0rec.h"
#include "rem0cmp.h"
#include "btr0btr.h"
#include "btr0sea.h"
#include "row0upd.h"
#include "trx0rec.h"
#include "que0que.h"
#include "row0row.h"
#include "srv0srv.h"
#include "ibuf0ibuf.h"
#include "lock0lock.h"
ibool btr_cur_print_record_ops = FALSE;
ulint btr_cur_rnd = 0;
ulint btr_cur_n_non_sea = 0;
ulint btr_cur_n_sea = 0;
ulint btr_cur_n_non_sea_old = 0;
ulint btr_cur_n_sea_old = 0;
/*页重组因子*/
#define BTR_CUR_PAGE_REORGANIZE_LIMIT (UNIV_PAGE_SIZE / 32)
#define BTR_KEY_VAL_ESTIMATE_N_PAGES 8
/*BLOB列的头结构*/
#define BTR_BLOB_HDR_PART_LEN 0 /*blob在对应页中的长度*/
#define BTR_BLOB_HDR_NEXT_PAGE_NO 4 /*下一个存有blob数据的page no*/
#define BTR_BLOB_HDR_SIZE 8
static void btr_cur_add_path_info(btr_cur_t* cursor, ulint height, ulint root_height);
static void btr_rec_free_updated_extern_fields(dict_index_t* index, rec_t* rec, upd_t* update, ibool do_not_free_inherited, mtr_t* mtr);
static ulint btr_rec_get_externally_stored_len(rec_t* rec);
/*对page做互斥latch并发*/
static void btr_cur_latch_leaves(dict_tree_t* tree, page_t* page, ulint space, ulint page_no, ulint latch_mode, btr_cur_t* cursor, mtr_t* mtr)
{
ulint left_page_no;
ulint right_page_no;
ut_ad(tree && page && mtr);
if(latch_mode == BTR_SEARCH_LEAF) /*查找时，可以直接获取一个S-LATCH,*/
btr_page_get(space, page_no, RW_S_LATCH, mtr);
else if(latch_mode == BTR_MODIFY_LEAF) /*叶子节点修改，直接对叶子节点x-latch即可*/
btr_page_get(space, page_no, RW_X_LATCH, mtr);
else if(latch_mode == BTR_MODIFY_TREE){ /*分别会获取前后两页和自己的x-latch*/
left_page_no = btr_page_get_prev(page, mtr);
if(left_pge_no != FIL_NULL) /*对前一页获取一个X-LATCH*/
btr_page_get(space, left_page_no, RW_X_LATCH, mtr);
btr_page_get(space, page_no, RW_X_LATCH, mtr);
/*对后一个页也获取一个X-LATCH*/
right_page_no = btr_page_get_next(page, mtr);
if(right_page_no != FIL_NULL)
btr_page_get(space, right_page_no, RW_X_LATCH, mtr);
}
else if(latch_mode == BTR_SEARCH_PREV){ /*搜索前一页，对前一页加上一个s-latch*/
left_page_no = btr_page_get_prev(page, mtr);
if(left_page_no != FIL_NULL)
cursor->left_page = btr_page_get(space, left_page_no, RW_S_LATCH, mtr);
btr_page_get(space, page_no, RW_S_LATCH, mtr);
}
else if(latch_mode == BTR_MODIFY_PREV){ /*更改前一页，对前一页加上一个x-latch*/
left_page_no = btr_page_get_prev(page, mtr);
if(left_page_no != FIL_NULL)
cursor->left_page = btr_page_get(space, left_page_no, RW_X_LATCH, mtr);
btr_page_get(space, page_no, RW_X_LATCH, mtr);
}
else
ut_error;
}
void btr_cur_search_to_nth_level(dict_index_t* index, ulint level, dtuple_t* tuple, ulint mode, ulint latch_mode,
btr_cur_t* cursor, ulint has_search_latch, mtr_t* mtr)
{
dict_tree_t* tree;
page_cur_t* page_cursor;
page_t* page;
page_t* guess;
rec_t* node_ptr;
ulint page_no;
ulint space;
ulint up_match;
ulint up_bytes;
ulint low_match;
ulint low_bytes;
ulint height;
ulint savepoint;
ulint rw_latch;
ulint page_mode;
ulint insert_planned;
ulint buf_mode;
ulint estimate;
ulint ignore_sec_unique;
ulint root_height;
btr_search_t* info;
ut_ad(level == 0 || mode == PAGE_CUR_LE);
ut_ad(dict_tree_check_search_tuple(index->tree, tuple));
ut_ad(!(index->type & DICT_IBUF) || ibuf_inside());
ut_ad(dtuple_check_typed(tuple));
insert_planned = latch_mode & BTR_INSERT;
estimate = latch_mode & BTR_ESTIMATE; /*预估计算的动作*/
ignore_sec_unique = latch_mode & BTR_IGNORE_SEC_UNIQUE;
latch_mode = latch_mode & ~(BTR_INSERT | BTR_ESTIMATE | BTR_IGNORE_SEC_UNIQUE);
ut_ad(!insert_planned || mode == PAGE_CUR_LE);
cursor->flag = BTR_CUR_BINARY;
cursor->index = index;
/*在自适应HASH表中查找*/
info = btr_search_get_info(index);
guess = info->root_guess;
#ifdef UNIV_SEARCH_PERF_STAT
info->n_searches++;
#endif
/*在自适应hash中找到了对应的记录*/
if (btr_search_latch.writer == RW_LOCK_NOT_LOCKED
&& latch_mode <= BTR_MODIFY_LEAF && info->last_hash_succ
&& !estimate
&& btr_search_guess_on_hash(index, info, tuple, mode, latch_mode, cursor, has_search_latch, mtr)) {
ut_ad(cursor->up_match != ULINT_UNDEFINED || mode != PAGE_CUR_GE);
ut_ad(cursor->up_match != ULINT_UNDEFINED || mode != PAGE_CUR_LE);
ut_ad(cursor->low_match != ULINT_UNDEFINED || mode != PAGE_CUR_LE);
btr_cur_n_sea++;
return;
}
btr_cur_n_sea ++;
if(has_search_latch)
rw_lock_s_unlock(&btr_search_latch);
/*设置一个mini transcation的保存点，以便mtr rollback*/
savepoint = mtr_set_savepoint(mtr);
tree = index->tree;
/*获取一个x-latch,更改有可能会更改索引*/
if(latch_mode == BTR_MODIFY_TREE)
mtr_x_lock(dict_tree_get_lock(tree), mtr);
else if(latch_mode == BTR_CONT_MODIFY_TREE)
ut_ad(mtr_memo_contains(mtr, dict_tree_get_lock(tree), MTR_MEMO_X_LOCK));
else /*对tree 索引获取一个s-latch*/
mtr_s_lock(dict_tree_get_lock(tree), mtr);
page_cursor = btr_cur_get_page_cur(cursor);
space = dict_tree_get_space(tree);
page_no = dict_tree_get_page(tree);
up_match = 0;
up_bytes = 0;
low_match = 0;
low_bytes = 0;
height = ULINT_UNDEFINED;
rw_latch = RW_NO_LATCH;
buf_mode = BUF_GET;
/*确定page记录的匹配模式*/
if (mode == PAGE_CUR_GE)
page_mode = PAGE_CUR_L;
else if (mode == PAGE_CUR_G)
page_mode = PAGE_CUR_LE;
else if (mode == PAGE_CUR_LE)
page_mode = PAGE_CUR_LE;
else {
ut_ad(mode == PAGE_CUR_L);
page_mode = PAGE_CUR_L;
}
for(;;){
if(height == 0 && latch_mode <= BTR_MODIFY_LEAF){
rw_latch = latch_mode;
/*尝试将page插入到ibuffer当中*/
if(insert_planned && ibuf_should_try(index, ignore_sec_unique))
buf_mode = BUF_GET_IF_IN_POOL;
}
retry_page_get:
page = buf_page_get_gen(space, page_no, rw_latch, guess, buf_mode, __FILE__, __LINE__, mtr);
if(page == NULL){
ut_ad(buf_mode == BUF_GET_IF_IN_POOL);
ut_ad(insert_planned);
ut_ad(cursor->thr);
/*page不能插入到insert buffer中,将会重试,知道page插入到ibuf中*/
if(ibuf_should_try(index, ignore_sec_unique) && ibuf_insert(tuple, index, space, page_no, cursor->thr)){
cursor->flag = BTR_CUR_INSERT_TO_IBUF;
return ;
}
buf_mode = BUF_GET;
goto retry_page_get;
}
ut_ad(0 == ut_dulint_cmp(tree->id, btr_page_get_index_id(page)));
if(height == ULINT_UNDEFINED){
height = btr_page_get_level(page, mtr);
root_height = height;
cursor->tree_height = root_height + 1;
if(page != guess)
info->root_guess = page;
}
if(height == 0){
if(rw_latch == RW_NO_LATCH)
btr_cur_latch_leaves(tree, page, space, page_no, latch_mode, cursor, mtr);
/*释放savepoint以下的mtr latch*/
if(latch_mode != BTR_MODIFY_TREE && latch_mode != BTR_CONT_MODIFY_TREE)
mtr_release_s_latch_at_savepoint(mtr, savepoint, dict_tree_get_lock(tree));
page_mode = mode;
}
/*在页中进行二分查找对应的记录,这个只是找page node ptr记录*/
page_cur_search_with_match(page, tuple, page_mode, &up_match, &up_bytes, &low_match, &low_bytes, page_cursor);
if(estimate) /*估算row数*/
btr_cur_add_path_info(cursor, height, root_height);
if(level == height){ /*已经找到对应的层了，不需要深入更低层上*/
if(level > 0)
btr_page_get(space, page_no, RW_X_LATCH, mtr);
break;
}
ut_ad(height > 0);
height --;
guess = NULL;
node_ptr = page_cur_get_rec(page_cursor);
/*获取孩子节点的page no*/
page_no = btr_node_ptr_get_child_page_no(node_ptr);
}
if(level == 0){
cursor->low_match = low_match;
cursor->low_bytes = low_bytes;
cursor->up_match = up_match;
cursor->up_bytes = up_bytes;
/*更新自适应HASH索引*/
btr_search_info_update(index, cursor);
ut_ad(cursor->up_match != ULINT_UNDEFINED || mode != PAGE_CUR_GE);
ut_ad(cursor->up_match != ULINT_UNDEFINED || mode != PAGE_CUR_LE);
ut_ad(cursor->low_match != ULINT_UNDEFINED || mode != PAGE_CUR_LE);
}
if(has_search_latch)
rw_lock_s_lock(&btr_search_latch);
}
/*将btree cursor定位到index索引范围的开始或者末尾，from_left = TRUE，表示定位到最前面*/
void btr_cur_open_at_index_side(ibool from_left, dict_index_t* index, ulint latch_mode, btr_cur_t* cursor, mtr_t* mtr)
{
page_cur_t* page_cursor;
dict_tree_t* tree;
page_t* page;
ulint page_no;
ulint space;
ulint height;
ulint root_height;
rec_t* node_ptr;
ulint estimate;
ulint savepoint;
estimate = latch_mode & BTR_ESTIMATE;
latch_mode = latch_mode & ~BTR_ESTIMATE;
tree = index->tree;
savepoint = mtr_set_savepoint(mtr);
if(latch_mode == BTR_MODIFY_TREE)
mtr_x_lock(dict_tree_get_lock(tree), mtr);
else
mtr_s_lock(dict_tree_get_lock(tree), mtr);
page_cursor = btr_cur_get_page_cur(cursor);
cursor->index = index;
space = dict_tree_get_space(tree);
page_no = dict_tree_get_page(tree);
height = ULINT_UNDEFINED;
for(;;){
page = buf_page_get_gen(space, page_no, RW_NO_LATCH, NULL,
BUF_GET, __FILE__, __LINE__, mtr);
ut_ad(0 == ut_dulint_cmp(tree->id, btr_page_get_index_id(page)));
if(height == ULINT_UNDEFINED){
height = btr_page_get_level(page, mtr);
root_height = height;
}
if(height == 0){
btr_cur_latch_leaves(tree, page, space, page_no, latch_mode, cursor, mtr);
if(latch_mode != BTR_MODIFY_TREE && latch_mode != BTR_CONT_MODIFY_TREE)
mtr_release_s_latch_at_savepoint(mtr, savepoint, dict_tree_get_lock(tree));
}
if(from_left) /*从页第一条记录*/
page_cur_set_before_first(page, page_cursor);
else /*从页的最后一条记录开始*/
page_cur_set_after_last(page, page_cursor);
if(height == 0){
if(estimate)
btr_cur_add_path_info(cursor, height, root_height);
break;
}
ut_ad(height > 0);
if(from_left)
page_cur_move_to_next(page_cursor);
else
page_cur_move_to_prev(page_cursor);
if(estimate)
btr_cur_add_path_info(cursor, height, root_height);
height --;
node_ptr = page_cur_get_rec(page_cursor);
page_no = btr_node_ptr_get_child_page_no(node_ptr);
}
}
/*在btree index的管辖范围，随机定位到一个位置*/
void btr_cur_open_at_rnd_pos(dict_index_t* index, ulint latch_mode, btr_cur_t* cursor, mtr_t* mtr)
{
page_cur_t* page_cursor;
dict_tree_t* tree;
page_t* page;
ulint page_no;
ulint space;
ulint height;
rec_t* node_ptr;
tree = index->tree;
if(latch_mode == BTR_MODIFY_TREE)
mtr_x_lock(dict_tree_get_lock(tree), mtr);
else
mtr_s_lock(dict_tree_get_lock(tree), mtr);
page_cursor = btr_cur_get_page_cur(cursor);
cursor->index = index;
space = dict_tree_get_space(tree);
page_no = dict_tree_get_page(tree);
height = ULINT_UNDEFINED;
for(;;){
page = buf_page_get_gen(space, page_no, RW_NO_LATCH, NULL, BUF_GET, __FILE__, __LINE__, mtr);
ut_ad(0 == ut_dulint_cmp(tree->id, btr_page_get_index_id(page)));
if(height == ULINT_UNDEFINED)
height = btr_page_get_level(page, mtr);
if(height == 0)
btr_cur_latch_leaves(tree, page, space, page_no, latch_mode, cursor, mtr);
/*随机定位一条记录，并将page cursor指向它*/
page_cur_open_on_rnd_user_rec(page, page_cursor);
if(height == 0)
break;
ut_ad(height > 0);
height --;
node_ptr = page_cur_get_rec(page_cursor);
page_no = btr_node_ptr_get_child_page_no(node_ptr);
}
}
static rec_t* btr_cur_insert_if_possible(btr_cur_t* cursor, dtuple_t* tuple, ibool* reorg, mtr_t* mtr)
{
page_cur_t* page_cursor;
page_t* page;
rec_t* rec;
ut_ad(dtuple_check_typed(tuple));
*reorg = FALSE;
page = btr_cur_get_page(cursor);
ut_ad(mtr_memo_contains(mtr, buf_block_align(page), MTR_MEMO_PAGE_X_FIX));
page_cursor = btr_cur_get_page_cur(cursor);
/*将tuple插入到page中*/
rec = page_cur_tuple_insert(page_cursor, tuple, mtr);
if(rec == NULL){
/*可能空间不够或者排序不对，进行页重组,有可能插入记录的空间无法在page上分配(没有空闲的rec空间，删除的单条记录 < tuple所需要的空间)*/
btr_page_reorganize(page, mtr);
*reorg = TRUE;
/*重新定位page游标*/
page_cur_search(page, tuple, PAGE_CUR_GE, page_cursor);
rec = page_cur_tuple_insert(page_cursor, tuple, mtr);
}
return rec;
}
/*为插入的记录添加一个事务锁和回滚日志*/
UNIV_INLINE ulint btr_cur_ins_lock_and_undo(ulint flags, btr_cur_t* cursor, dtuple_t* entry, que_thr_t* thr, ibool* inherit)
{
dict_index_t* index;
ulint err;
rec_t* rec;
dulint roll_ptr;
rec = btr_cur_get_rec(cursor);
index = cursor->index;
/*添加一个事务锁，如果有对应的行锁，重复利用*/
err = lock_rec_insert_check_and_lock(flags, rec, index, thr, inherit);
if(err != DB_SUCCESS) /*添加锁失败*/
return err;
if(index->type & DICT_CLUSTERED && !(index->type & DICT_IBUF)){
err = trx_undo_report_row_operation(flags, TRX_UNDO_INSERT_OP, thr, index, entry,
NULL, 0, NULL, &roll_ptr);
if(err != DB_SUCCESS)
return err;
if(!(flags & BTR_KEEP_SYS_FLAG))
row_upd_index_entry_sys_field(entry, index, DATA_ROLL_PTR, roll_ptr);
}
return DB_SUCCESS;
}
/*尝试以乐观式插入记录*/
ulint btr_cur_optimistic_insert(ulint flags, btr_cur_t* cursor, dtuple_t* entry, rec_t** rec, big_rec_t** big_rec, que_thr_t* thr, mtr_t* mtr)
{
big_rec_t* big_rec_vec = NULL;
dict_index_t* index;
page_cur_t* page_cursor;
page_t* page;
ulint max_size;
rec_t* dummy_rec;
ulint level;
ibool reorg;
ibool inherit;
ulint rec_size;
ulint data_size;
ulint extra_size;
ulint type;
ulint err;
*big_rec = NULL;
page = btr_cur_get_page(cursor);
index = cursor->index;
if(!dtuple_check_typed_no_assert(entry))
fprintf(stderr, "InnoDB: Error in a tuple to insert into table %lu index %s\n",
index->table_name, index->name);
if (btr_cur_print_record_ops && thr) {
printf("Trx with id %lu %lu going to insert to table %s index %s\n",
ut_dulint_get_high(thr_get_trx(thr)->id),
ut_dulint_get_low(thr_get_trx(thr)->id),
index->table_name, index->name);
dtuple_print(entry);
}
ut_ad(mtr_memo_contains(mtr, buf_block_align(page), MTR_MEMO_PAGE_X_FIX));
/*page可以容纳的最大记录空间*/
max_size = page_get_max_insert_size_after_reorganize(page, 1);
level = btr_page_get_level(page, mtr); /*获得page所处的层*/
calculate_sizes_again:
/*获得tuple存储需要的空间大小*/
data_size = dtuple_get_data_size(entry);
/*获得rec header需要的长度*/
extra_size = rec_get_converted_extra_size(data_size, dtuple_get_n_fields(entry));
rec_size = data_size + extra_size;
/*记录超出最大的存储范围，将其转化为big_rec*/
if((rec_size >= page_get_free_space_of_empty() / 2) || rec_size >= REC_MAX_DATA_SIZE){
big_rec_vec = dtuple_convert_big_rec(index, entry, NULL, 0);
/*转化失败,记录实在太大,可能有太多的短列？*/
if(big_rec_vec == NULL)
return DB_TOO_BIG_RECORD;
goto calculate_sizes_again;
}
type = index->type;
/*聚集索引，在叶子节点可以进行左右分裂,而且BTREE树的空间不够？？不能存入，将转化为big_rec的操作回滚*/
if ((type & DICT_CLUSTERED)
&& (dict_tree_get_space_reserve(index->tree) + rec_size > max_size)
&& (page_get_n_recs(page) >= 2)
&& (0 == level)
&& (btr_page_get_split_rec_to_right(cursor, &dummy_rec)
|| btr_page_get_split_rec_to_left(cursor, &dummy_rec))){
if(big_rec_vec) /*将tuple转化成big_rec*/
dtuple_convert_back_big_rec(index, entry, big_rec_vec);
return DB_FAIL;
}
if (!(((max_size >= rec_size) && (max_size >= BTR_CUR_PAGE_REORGANIZE_LIMIT))
|| page_get_max_insert_size(page, 1) >= rec_size || page_get_n_recs(page) <= 1)) {
if(big_rec_vec)
dtuple_convert_back_big_rec(index, entry, big_rec_vec);
return DB_FAIL;
}
err = btr_cur_ins_lock_and_undo(flags, cursor, entry, thr, &inherit);
if(err != DB_SUCCESS){ /*事务加锁不成功，回滚big_rec*/
if(big_rec_vec)
dtuple_convert_back_big_rec(index, entry, big_rec_vec);
return err;
}
page_cursor = btr_cur_get_page_cur(cursor);
reorg = FALSE;
/*将tuple插入到page当中*/
*rec = page_cur_insert_rec_low(page_cursor, entry, data_size, NULL, mtr);
if(*rec == NULL){ /*插入失败，进行page重组*/
btr_page_reorganize(page, mtr);
ut_ad(page_get_max_insert_size(page, 1) == max_size);
reorg = TRUE;
page_cur_search(page, entry, PAGE_CUR_LE, page_cursor);
*rec = page_cur_tuple_insert(page_cursor, entry, mtr);
if(*rec == NULL){ /*重组后还是失败，打印错误信息*/
char* err_buf = mem_alloc(1000);
dtuple_sprintf(err_buf, 900, entry);
fprintf(stderr, "InnoDB: Error: cannot insert tuple %s to index %s of table %s\n"
"InnoDB: max insert size %lu\n", err_buf, index->name, index->table->name, max_size);
mem_free(err_buf);
}
ut_a(*rec);
}
/*更新HASH索引*/
if(!reorg && level == 0 && cursor->flag == BTR_CUR_HASH)
btr_search_update_hash_node_on_insert(cursor);
else
btr_search_update_hash_on_insert(cursor);
/*继承后一行事务锁(GAP方式)*/
if(!(flags & BTR_NO_LOCKING_FLAG) && inherit)
lock_update_insert(*rec);
/*非聚集索引插入*/
if(!(type & DICT_CLUSTERED))
ibuf_update_free_bits_if_full(cursor->index, page, max_size,
rec_size + PAGE_DIR_SLOT_SIZE);
*big_rec = big_rec_vec;
return DB_SUCCESS;
}
/*以悲观执行记录的插入,悲观方式是表空间不够，需要扩大表空间*/
ulint btr_cur_pessimistic_insert(ulint flags, btr_cur_t* cursor, dtuple_t* entry, rec_t** rec, big_rec_t** big_rec, que_thr_t* thr, mtr_t* mtr)
{
dict_index_t* index = cursor->index;
big_rec_t* big_rec_vec = NULL;
page_t* page;
ulint err;
ibool dummy_inh;
ibool success;
ulint n_extents = 0;
*big_rec = NULL;
page = btr_cur_get_page(cursor);
ut_ad(mtr_memo_contains(mtr, dict_tree_get_lock(btr_cur_get_tree(cursor)), MTR_MEMO_X_LOCK));
ut_ad(mtr_memo_contains(mtr, buf_block_align(page), MTR_MEMO_PAGE_X_FIX));
cursor->flag = BTR_CUR_BINARY;
err = btr_cur_optimistic_insert(flags, cursor, entry, rec, big_rec, thr, mtr);
if(err != DB_FAIL) /*乐观锁方式插入成功，直接返回*/
return err;
err = btr_cur_ins_lock_and_undo(flags, cursor, entry, thr, &dummy_inh);
if(err != DB_SUCCESS)
return err;
if(!(flags && BTR_NO_UNDO_LOG_FLAG)){
n_extents = cursor->tree_height / 16 + 3;
/*扩大file space表空间*/
success = fsp_reserve_free_extents(index->space, n_extents, FSP_NORMAL, mtr);
if(!success){ /*超出表空间范围*/
err = DB_OUT_OF_FILE_SPACE;
return err;
}
}
/*单个页无法存储entry记录,作为大记录存储*/
if(rec_get_converted_size(entry) >= page_get_free_space_of_empty() / 2 || rec_get_converted_size(entry) >= REC_MAX_DATA_SIZE){
big_rec_vec = dtuple_convert_big_rec(index, entry, NULL, 0);
if(big_rec_vec == NULL)
return DB_TOO_BIG_RECORD;
}
if (dict_tree_get_page(index->tree) == buf_frame_get_page_no(page))
*rec = btr_root_raise_and_insert(cursor, entry, mtr);
else
*rec = btr_page_split_and_insert(cursor, entry, mtr);
btr_cur_position(index, page_rec_get_prev(*rec), cursor);
/*更新自适应HASH*/
btr_search_update_hash_on_insert(cursor);
/*新插入行对gap行锁的继承*/
if(!(flags & BTR_NO_LOCKING_FLAG))
lock_update_insert(*rec);
err = DB_SUCCESS;
if(n_extents > 0)
fil_space_release_free_extents(index->space, n_extents);
*big_rec = big_rec_vec;
return err;
}
/*按聚集索引修改记录，进行事务锁请求*/
UNIV_INLINE ulint btr_cur_upd_lock_and_undo(ulint flags, btr_cur_t* cursor, upd_t* update, ulint cmpl_info, que_thr_t* thr, dulint roll_ptr)
{
dict_index_t* index;
rec_t* rec;
ulint err;
ut_ad(cursor && update && thr && roll_ptr);
ut_ad(cursor->index->type & DICT_CLUSTERED);
rec = btr_cur_get_rec(cursor);
index = cursor->index;
err =DB_SUCCESS;
if(!(flags & BTR_NO_LOCKING_FLAG)){
/*检查修改记录时，记录聚集索引上是否有锁（包括显式锁和隐式锁）*/
err = lock_clust_rec_modify_check_and_lock(flags, rec, index, thr);
if(err != DB_SUCCESS)
return err;
}
err = trx_undo_report_row_operation(flags, TRX_UNDO_MODIFY_OP, thr, index, NULL, update,
cmpl_info, rec, roll_ptr);
return err;
}
/*为update record增加一条redo log*/
UNIV_INLINE void btr_cur_update_in_place_log(ulint flags, rec_t* rec, dict_index_t* index,
upd_t* update, trx_t* trx, dulint roll_ptr, mtr_t* mtr)
{
byte* log_ptr;
log_ptr = mlog_open(mtr, 30 + MLOG_BUF_MARGIN);
log_ptr = mlog_write_initial_log_record_fast(rec, MLOG_REC_UPDATE_IN_PLACE, log_ptr, mtr);
mach_write_to_1(log_ptr, flags);
log_ptr++;
log_ptr = row_upd_write_sys_vals_to_log(index, trx, roll_ptr, log_ptr, mtr);
mach_write_to_2(log_ptr, rec - buf_frame_align(rec));
log_ptr += 2;
row_upd_index_write_log(update, log_ptr, mtr);
}
/*解析一条修改记录的redo log并进行重演*/
byte* btr_cur_parse_update_in_place(byte* ptr, byte* end_ptr, page_t* page, mtr_t* mtr)
{
ulint flags;
rec_t* rec;
upd_t* update;
ulint pos;
dulint trx_id;
dulint roll_ptr;
ulint rec_offset;
mem_heap_t* heap;
if(end_ptr < ptr + 1)
return NULL;
flags = mach_read_from_1(ptr);
ptr++;
ptr = row_upd_parse_sys_vals(ptr, end_ptr, &pos, &trx_id, &roll_ptr);
if(ptr == NULL)
return NULL;
if(end_ptr < ptr + 2)
return NULL;
/*从redo log中读取修改记录的偏移*/
rec_offset = mach_read_from_2(ptr);
ptr += 2;
/*从redo log中读取修改的内容*/
heap = mem_heap_create(256);
ptr = row_upd_index_parse(ptr, end_ptr, heap, &update);
if(ptr == NULL){
mem_heap_free(heap);
return NULL;
}
if(page == NULL){
mem_heap_free(heap);
return NULL;
}
rec = page + rec_offset;
if(!(flags & BTR_KEEP_SYS_FLAG))
row_upd_rec_sys_fields_in_recovery(rec, pos, trx_id, roll_ptr);
/*进行记录修改*/
row_upd_rec_in_place(heap, update);
mem_heap_free(heap);
return ptr;
}
/*通过辅助索引修改对应的记录*/
ulint btr_cur_update_sec_rec_in_place(btr_cur_t* cursor, upd_t* update, que_thr_t* thr, mtr_t* mtr)
{
dict_index_t* index = cursor->index;
dict_index_t* clust_index;
ulint err;
rec_t* rec;
dulint roll_ptr = ut_dulint_zero;
trx_t* trx = thr_get_trx(thr);
ut_ad(0 == (index->type & DICT_CLUSTERED));
rec = btr_cur_get_rec(cursor);
if(btr_cur_print_record_ops && thr){
printf("Trx with id %lu %lu going to update table %s index %s\n",
ut_dulint_get_high(thr_get_trx(thr)->id),ut_dulint_get_low(thr_get_trx(thr)->id), index->table_name, index->name);
rec_print(rec);
}
/*通过二级索引获得行上的锁*/
err = lock_sec_rec_modify_check_and_lock(0, rec, index, thr);
if(err != DB_SUCCESS)
return err;
/*删除自适应HASH对应关系*/
btr_search_update_hash_on_delete(cursor);
/*对记录进行修改*/
row_upd_rec_in_place(rec, update);
/*通过二级索引找到聚集索引*/
clust_index = dict_table_get_first_index(index->table);
/*通过聚集索引添加一条修改记录的redo log*/
btr_cur_update_in_place_log(BTR_KEEP_SYS_FLAG, rec, clust_index, update, trx, roll_ptr, mtr);
return DB_SUCCESS;
}
ulint btr_cur_update_in_place(ulint flags, btr_cur_t* cursor, upd_t* update, ulint cmpl_info, que_thr_t* thr, mtr_t* mtr)
{
dict_index_t* index;
buf_block_t* block;
ulint err;
rec_t* rec;
dulint roll_ptr;
trx_t* trx;
ibool was_delete_marked;
ut_ad(cursor->index->type & DICT_CLUSTERED);
/*获得对应的记录、索引、事务*/
rec = btr_cur_get_rec(cursor);
index = cursor->index;
trx = thr_get_trx(thr);
if(btr_cur_print_record_ops && thr){
printf("Trx with id %lu %lu going to update table %s index %s\n",
ut_dulint_get_high(thr_get_trx(thr)->id),
ut_dulint_get_low(thr_get_trx(thr)->id),
index->table_name, index->name);
rec_print(rec);
}
/*获得事务的行锁*/
err = btr_cur_upd_lock_and_undo(flags, cursor, update, cmpl_info, thr, &roll_ptr);
if(err != DB_SUCCESS)
return err;
block = buf_block_align(rec);
if(block->is_hashed){
if (row_upd_changes_ord_field_binary(NULL, index, update))
btr_search_update_hash_on_delete(cursor);
rw_lock_x_lock(&btr_search_latch);
}
if(!(flags & BTR_KEEP_SYS_FLAG))
row_upd_rec_sys_fields(rec, index, trx, roll_ptr);
was_delete_marked = rec_get_deleted_flag(rec);
/*进行记录更新*/
row_upd_rec_in_place(rec, update);
if(block->is_hashed)
rw_lock_x_unlock(&btr_search_latch);
btr_cur_update_in_place_log(flags, rec, index, update, trx, roll_ptr, mtr);
/*由删除状态变成未删除状态*/
if(was_delete_marked && !rec_get_deleted_flag(rec))
btr_cur_unmark_extern_fields(rec, mtr);
return DB_SUCCESS;
}
/*乐观方式更新一条记录，先尝试在原来的记录位置直接更新，如果不能就会将原来的记录删除，将更新的内容组成一条记录插入到对应的page中*/
ulint btr_cur_optimistic_update(ulint flags, btr_cur_t* cursor, upd_t* update, ulint cmpl_info, que_thr_t* thr, mtr_t* mtr)
{
dict_index_t* index;
page_cur_t* page_cursor;
ulint err;
page_t* page;
rec_t* rec;
ulint max_size;
ulint new_rec_size;
ulint old_rec_size;
dtuple_t* new_entry;
dulint roll_ptr;
trx_t* trx;
mem_heap_t* heap;
ibool reorganized = FALSE;
ulint i;
ut_ad((cursor->index)->type & DICT_CLUSTERED);
page = btr_cur_get_page(cursor);
rec = btr_cur_get_rec(cursor);
index = cursor->index;
if (btr_cur_print_record_ops && thr) {
printf("Trx with id %lu %lu going to update table %s index %s\n",
ut_dulint_get_high(thr_get_trx(thr)->id),
ut_dulint_get_low(thr_get_trx(thr)->id),
index->table_name, index->name);
rec_print(rec);
}
ut_ad(mtr_memo_contains(mtr, buf_block_align(page), MTR_MEMO_BUF_FIX));
/*不能改变列的大小，直接在原来的记录位置做更新*/
if(!row_upd_changes_field_size(rec, index, update))
return btr_cur_update_in_place(flags, cursor, update, cmpl_info, thr, mtr);
/*判断列是否溢出*/
for(i = 0; i < upd_get_n_fields(update); i++){
if(upd_get_nth_field(update, i)->extern_storage)
return DB_OVERFLOW;
}
/*列已是两个字节表示长度*/
if(rec_contains_externally_stored_field(btr_cur_get_rec(cursor)))
return DB_OVERFLOW;
page_cursor = btr_cur_get_page_cur(cursor);
heap = mem_heap_create(1024);
/*在内存中构建一个新记录的存储对象记录*/
new_entry = row_rec_to_index_entry(ROW_COPY_DATA, index, rec, heap);
row_upd_clust_index_replace_new_col_vals(new_entry, update);
old_rec_size = rec_get_size(rec);
new_rec_size = rec_get_converted_size(new_entry);
/*跟新的记录大小已经超过页能存储的大小*/
if(new_rec_size >= page_get_free_space_of_empty() / 2){
mem_heap_free(heap);
return DB_OVERFLOW;
}
/*计算页重组后可以存储的最大空间*/
max_size = old_rec_size + page_get_max_insert_size_after_reorganize(page, 1);
if(page_get_data_size(page) - old_rec_size + new_rec_size < BTR_CUR_PAGE_COMPRESS_LIMIT){
/*记录更新后会触发btree的合并填充，不做直接更新*/
mem_heap_free(heap);
return DB_UNDERFLOW;
}
/*能存储的空间小于合并的空间阈值或者不能存下新的记录,并且page的空间不只1条记录*/
if(!((max_size >= BTR_CUR_PAGE_REORGANIZE_LIMIT && max_size >= new_rec_size) || page_get_n_recs(page) <= 1)){
mem_heap_free(heap);
return DB_OVERFLOW;
}
/*不能对记录加事务锁*/
err = btr_cur_upd_lock_and_undo(flags, cursor, update, cmpl_info, thr, &roll_ptr);
if(err != DB_SUCCESS){
mem_heap_free(heap);
return err;
}
/*将记录的行锁全部转移到infimum,应该是临时存储在这个地方*/
lock_rec_store_on_page_infimum(rec);
btr_search_update_hash_on_delete(cursor);
/*将page游标对应的记录删除*/
page_cur_delete_rec(page_cursor, mtr);
/*游标移到前面一条记录上*/
page_cur_move_to_prev(page_cursor);
trx = thr_get_trx(thr);
if(!(flags & BTR_KEEP_SYS_FLAG)){
row_upd_index_entry_sys_field(new_entry, index, DATA_ROLL_PTR, roll_ptr);
row_upd_index_entry_sys_field(new_entry, index, DATA_TRX_ID, trx->id);
}
/*将新构建的tuple记录插入到页中*/
rec = btr_cur_insert_if_possible(cursor, new_entry, &reorganized, mtr);
ut_a(rec);
if(!rec_get_deleted_flag(rec))
btr_cur_unmark_extern_fields(rec, mtr);
/*将缓存在infimum上的锁恢复到新插入的记录上*/
lock_rec_restore_from_page_infimum(rec, page);
page_cur_move_to_next(page_cursor);
mem_heap_free(heap);
return DB_SUCCESS;
}
static void btr_cur_pess_upd_restore_supremum(rec_t* rec, mtr_t* mtr)
{
page_t* page;
page_t* prev_page;
ulint space;
ulint prev_page_no;
page = buf_frame_align(rec);
if(page_rec_get_next(page_get_infimum_rec(page) != rec))
return;
/*获得rec前一页的page对象*/
space = buf_frame_get_space_id(page);
prev_page_no = btr_page_get_prev(page, mtr);
ut_ad(prev_page_no != FIL_NULL);
prev_page = buf_page_get_with_no_latch(space, prev_page_no, mtr);
/*确定已经拥有x-latch*/
ut_ad(mtr_memo_contains(mtr, buf_block_align(prev_page), MTR_MEMO_PAGE_X_FIX));
/*前一个page的supremum继承rec上的锁*/
lock_rec_reset_and_inherit_gap_locks(page_get_supremum_rec(prev_page), rec);
}