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ibuf0ibuf.cc
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#include "ibuf0ibuf.h"
#include "buf0buf.h"
#include "buf0rea.h"
#include "fsp0fsp.h"
#include "trx0sys.h"
#include "fil0fil.h"
#include "thr0loc.h"
#include "rem0rec.h"
#include "btr0cur.h"
#include "btr0pcur.h"
#include "btr0btr.h"
#include "sync0sync.h"
#include "dict0boot.h"
#include "fut0lst.h"
#include "lock0lock.h"
#include "log0recv.h"
#include "que0que.h"
/* Buffer pool size per the maximum insert buffer size */
#define IBUF_POOL_SIZE_PER_MAX_SIZE 2
/*ibuf的全局对象*/
ibuf_t* ibuf = NULL;
ulint ibuf_rnd = 986058871;
ulint ibuf_flush_count = 0;
#define IBUF_COUNT_N_SPACES 10
#define IBUF_COUNT_N_PAGES 10000
/*用于调试的ibuf的page记录统计器*/
ulint* ibuf_counts[IBUF_COUNT_N_SPACES];
ibool ibuf_counts_inited = FALSE;
#define IBUF_BITMAP PAGE_DATA;
#define IBUF_BITMAP_FREE 0
#define IBUF_BITMAP_BUFFERED 2
#define IBUF_BITMAP_IBUF 3
#define IBUF_BITS_PER_PAGE 4
/* The mutex used to block pessimistic inserts to ibuf trees */
mutex_t ibuf_pessimistic_insert_mutex;
/*insert buffer结构保护latch*/
mutex_t ibuf_mutex;
/*insert buffer bitmap结构保护latch*/
mutex_t ibuf_bitmap_mutex;
#define IBUF_MERGE_AREA 8
#define IBUF_MERGE_THRESHOLD 4
#define IBUF_MAX_N_PAGES_MERGED IBUF_MERGE_AREA
#define IBUF_CONTRACT_ON_INSERT_NON_SYNC 0
#define IBUF_CONTRACT_ON_INSERT_SYNC 5
#define IBUF_CONTRACT_DO_NOT_INSERT 10
/*insert buffer结构合法性判断*/
static ibool ibuf_validate_low(void);
/*设置当前os thread的ibuf标识*/
UNIV_INLINE void ibuf_enter()
{
ibool* ptr;
ptr = thr_local_get_in_ibuf_field();
ut_ad(*ptr == FALSE);
*ptr = TRUE;
}
UNIV_INLINE void ibuf_exit()
{
ibool* ptr;
ptr = thr_local_get_in_ibuf_field();
ut_ad(*ptr = TRUE);
*ptr = FALSE;
}
/*判断当前os thread是否在操作ibuf*/
ibool ibuf_inside()
{
return *thr_local_get_in_ibuf_field();
}
/*获得ibuf header page,并且对其加上rw_x_latch*/
static page_t* ibuf_header_page_get(ulint space, mtr_t* mtr)
{
page_t* page;
ut_ad(!ibuf_inside());
/*获得ibuf头页*/
page = buf_page_get(space, FSP_IBUF_HEADER_PAGE_NO, RW_X_LATCH, mtr);
buf_page_dbg_add_level(page, SYNC_IBUF_HEADER);
return page;
}
/*获得ibuf btree的root page,并且对其加上rw_x_latch*/
static page_t* ibuf_tree_root_get(ibuf_data_t* data, ulint space, mtr_t* mtr)
{
page_t* page;
ut_ad(ibuf_inside());
mtr_x_lock(dict_tree_get_lock((data->index)->tree), mtr);
page = buf_page_get(space, FSP_IBUF_TREE_ROOT_PAGE_NO, RW_X_LATCH, mtr);
buf_page_dbg_add_level(page, SYNC_TREE_NODE);
return page;
}
/*获得指定page的ibuf count*/
ulint ibuf_count_get(ulint space, ulint page_no)
{
ut_ad(space < IBUF_COUNT_N_SPACES);
ut_ad(page_no < IBUF_COUNT_N_PAGES);
if(!ibuf_counts_inited)
return 0;
return *(ibuf_counts[space] + page_no);
}
/*设置指定page的ibuf count*/
static void ibuf_count_set(ulint space, ulint page_no, ulint val)
{
ut_ad(space < IBUF_COUNT_N_SPACES);
ut_ad(page_no < IBUF_COUNT_N_PAGES);
ut_ad(val < UNIV_PAGE_SIZE);
*(ibuf_counts[space] + page_no) = val;
}
/*创建ibuf 全局对象并初始化，并且初始化表空间*/
void ibuf_init_at_db_start()
{
ibuf = mem_alloc(sizeof(ibuf_t));
/*ibuf最大占用的内存空间为缓冲池的1/2, max_size是指页数，不是字节数*/
ibuf->max_size = buf_pool_get_curr_size() / (UNIV_PAGE_SIZE * IBUF_POOL_SIZE_PER_MAX_SIZE);
ibuf->meter = IBUF_THRESHOLD + 1;
UT_LIST_INIT(ibuf->data_list);
ibuf->size = 0;
/*对ibuf_counts的初始化*/
{
ulint i, j;
for (i = 0; i < IBUF_COUNT_N_SPACES; i++) {
ibuf_counts[i] = mem_alloc(sizeof(ulint)
* IBUF_COUNT_N_PAGES);
for (j = 0; j < IBUF_COUNT_N_PAGES; j++) {
ibuf_count_set(i, j, 0);
}
}
}
/*创建线程并发的latch对象*/
mutex_create(&ibuf_pessimistic_insert_mutex);
mutex_set_level(&ibuf_pessimistic_insert_mutex, SYNC_IBUF_PESS_INSERT_MUTEX);
mutex_create(&ibuf_mutex);
mutex_set_level(&ibuf_mutex, SYNC_IBUF_MUTEX);
mutex_create(&ibuf_bitmap_mutex);
mutex_set_level(&ibuf_bitmap_mutex, SYNC_IBUF_BITMAP_MUTEX);
/*初始化ibuf对应的表空间文件,会建立ibuf_data与space之间的关系*/
fil_ibuf_init_at_db_start();
ibuf_counts_inited = TRUE;
}
/*更新ibuf data的空间大小信息，假设segment的大小没做改变的情况下计算*/
static void ibuf_data_sizes_update(ibuf_data_t* data, page_t* root, mtr_t* mtr)
{
ulint old_size;
ut_ad(mutex_own(&ibuf_mutex));
old_size = data->size;
/*获得root page头中的ibuf free list*/
data->free_list_len = flst_get_len(root + PAGE_HEADER + PAGE_BTR_IBUF_FREE_LIST, mtr);
/*获得ibuf btree的层高*/
data->height = btr_page_get_level(root, mtr) + 1;
/*获得data占用的页数,一个是root page的本身*/
data->size = data->seg_size - (1 + data->free_list_len);
ut_ad(data->size < data->seg_size);
/*判断整个ibuf btree上是否有用户记录*/
if(page_get_n_recs(root) > 0)
data->empty = TRUE;
else
data->empty = FALSE;
ut_ad(ibuf->size + data->size >= old_size);
/*更新ibuf size，意思就是加上data->size 与old_size之间的差值*/
ibuf->size = ibuf->size + data->size - old_size;
}
/*创建一个单独基于ibuf的表空间，这个函数会在fil_ibuf_init_at_db_start之中调用*/
ibuf_data_t* ibuf_data_init_for_space(ulint space)
{
ibuf_data_t* data;
page_t* root;
page_t* header_page;
mtr_t mtr;
char buf[50];
dict_table_t* table;
dict_index_t* index;
ulint n_used;
data = mem_alloc(sizeof(ibuf_data_t));
data->space = space;
mtr_start(&mtr);
mutex_enter(&ibuf_mutex);
mtr_x_lock(fil_space_get_latch(space), &mtr);
/*获得ibuf头页*/
header_page = ibuf_header_page_get(space, &mtr);
/*计算ibuf segment之中有多少页被占用了*/
fseg_n_reserved_pages(header_page + IBUF_HEADER + IBUF_TREE_SEG_HEADER, &n_used, &mtr);
ibuf_enter();
/*第一个page为header页，第二个page为insert bitmap*/
ut_ad(n_used >= 2);
data->seg_size = n_used;
root = buf_page_get(space, FSP_IBUF_TREE_ROOT_PAGE_NO, RW_X_LATCH, &mtr);
buf_page_dbg_add_level(root, SYNC_TREE_NODE);
data->size = 0;
data->n_inserts = 0;
data->n_merges = 0;
data->n_merged_recs = 0;
/*更新ibuf->size*/
ibuf_data_sizes_update(data, root, &mtr);
mutex_exit(&ibuf_mutex);
mtr_commit(&mtr);
ibuf_exit();
/*在表字典中建立一张对应的ibuf表*/
sprintf(buf, "SYS_IBUF_TABLE_%lu", space);
table = dict_mem_table_create(buf, space, 2);
dict_mem_table_add_col(table, "PAGE_NO", DATA_BINARY, 0, 0, 0);
dict_mem_table_add_col(table, "TYPES", DATA_BINARY, 0, 0, 0);
table->id = ut_dulint_add(DICT_IBUF_ID_MIN, space);
dict_table_add_to_cache(table);
index = dict_mem_index_create(buf, "CLUST_IND", space, DICT_CLUSTERED | DICT_UNIVERSAL | DICT_IBUF, 2);
dict_mem_index_add_field(index, "PAGE_NO", 0);
dict_mem_index_add_field(index, "TYPES", 0);
index->page_no = FSP_IBUF_TREE_ROOT_PAGE_NO;
index->id = ut_dulint_add(DICT_IBUF_ID_MIN, space); /*ibuf的索引ID从DICT_IBUF_ID_MIN开始分配，为了避免和常规的索引ID重复*/
dict_index_add_to_cache(table, index);
data->index = dict_table_get_first_index(table);
/*将ibuf_data加入到ibuf中*/
mutex_enter(&ibuf_mutex);
UT_LIST_ADD_LAST(data_list, ibuf->data_list, data);
mutex_exit(&ibuf_mutex);
return data;
}
/*初始化ibuf bitamp age*/
void ibuf_bitmap_page_init(page_t* page, mtr_t* mtr)
{
ulint bit_offset;
ulint byte_offset;
ulint i;
bit_offset = XDES_DESCRIBED_PER_PAGE * IBUF_BITS_PER_PAGE;
byte_offset = bit_offset / 8 + 1;
/*初始化为0*/
for(i = IBUF_BITMAP; i < IBUF_BITMAP + byte_offset; i ++)
*(page + 1) = 0;
/*写入一条初始化ibuf bitmap的mtr log*/
mlog_write_initial_log_record(page, MLOG_IBUF_BITMAP_INIT, mtr);
}
/*对初始化bitmap mtr log的重演*/
byte* ibuf_parse_bitmap_init(byte* ptr, byte* end_ptr, page_t* page, mtr_t* mtr)
{
ut_ad(ptr && end_ptr);
if(page)
ibuf_bitmap_page_init(page, mtr);
return ptr;
}
/*从ibuf bitmap中获取指定页的bitmap信息（一个4bit的整形数）*/
UNIV_INLINE ulint ibuf_bitmap_page_get_bits(page_t* page, ulint page_no, ulint bit, mtr_t* mtr)
{
ulint byte_offset;
ulint bit_offset;
ulint map_byte;
ulint value;
ut_ad(bit < IBUF_BITS_PER_PAGE);
ut_ad(IBUF_BITS_PER_PAGE % 2 == 0);
ut_ad(mtr_memo_contains(mtr, buf_block_align(page), MTR_MEMO_PAGE_X_FIX));
/*一个page在bit当中占4位*/
bit_offset = (page_no % XDES_DESCRIBED_PER_PAGE) * IBUF_BITS_PER_PAGE + bit;
byte_offset = bit_offset / 8;
bit_offset = bit_offset % 8;
ut_ad(byte_offset + IBUF_BITMAP < UNIV_PAGE_SIZE);
map_byte = mach_read_from_1(page + IBUF_BITMAP + byte_offset);
value = ut_bit_get_nth(map_byte, bit_offset);
/*如果是取page剩余空间的话，那么是取前面2位*/
if(bit == IBUF_BITMAP_FREE){
ut_ad(bit_offset + 1 < 0);
value = (value << 1) + ut_bit_get_nth(map_byte, bit_offset + 1);
}
return value;
}
/*设置一个page的ibuf bitmap信息*/
static void ibuf_bitmap_page_set_bits(page_t* page, ulint page_no, ulint bit, ulint val, mtr_t* mtr)
{
ulint byte_offset;
ulint bit_offset;
ulint map_byte;
ut_ad(bit < IBUF_BITS_PER_PAGE);
ut_ad(IBUF_BITS_PER_PAGE % 2 == 0);
ut_ad(mtr_memo_contains(mtr, buf_block_align(page), MTR_MEMO_PAGE_X_FIX));
/*计算page对应的bitmap位置*/
bit_offset = (page_no % XDES_DESCRIBED_PER_PAGE) * IBUF_BITS_PER_PAGE + bit;
byte_offset = bit_offset / 8;
bit_offset = bit_offset % 8;
ut_ad(byte_offset + IBUF_BITMAP < UNIV_PAGE_SIZE);
map_byte = mach_read_from_1(page + IBUF_BITMAP + byte_offset);
/*设置页的剩余空间*/
if (bit == IBUF_BITMAP_FREE){
ut_ad(bit_offset + 1 < 8);
ut_ad(val <= 3);
map_byte = ut_bit_set_nth(map_byte, bit_offset, val / 2);
map_byte = ut_bit_set_nth(map_byte, bit_offset + 1, val % 2);
}
else{
ut_ad(val <= 1);
map_byte = ut_bit_set_nth(map_byte, bit_offset, val);
}
/*记录一条设置page bitmap信息的mtr log*/
mlog_write_ulint(page + IBUF_BITMAP + byte_offset, map_byte, MLOG_1BYTE, mtr);
}
/*计算page_no的ibuf bitmap信息所在的bitmap page的序号位置*/
UNIV_INLINE ulint ibuf_bitmap_page_no_calc(ulint page_no)
{
return FSP_IBUF_BITMAP_OFFSET + XDES_DESCRIBED_PER_PAGE * (page_no / XDES_DESCRIBED_PER_PAGE);
}
/*通过space 和page no获得对应page的bitmap所在的bitmap page对象*/
static page_t* ibuf_bitmap_get_map_page(ulint space, ulint page_no, mtr_t* mtr)
{
page_t* page;
page = buf_page_get(space, ibuf_bitmap_page_no_calc(page_no), RW_X_LATCH, mtr);
buf_page_dbg_add_level(page, SYNC_IBUF_BITMAP);
return page;
}
/*设置page对应的ibuf bitmap信息*/
UNIV_INLINE void ibuf_set_free_bits_low(ulint type, page_t* page, ulint val, mtr_t* mtr)
{
page_t* bitmap_page;
/*是聚集索引*/
if(type & DICT_CLUSTERED)
return ;
/*不是btree的叶子节点*/
if (btr_page_get_level_low(page) != 0)
return;
bitmap_page = ibuf_bitmap_get_map_page(buf_frame_get_space_id(page), buf_frame_get_page_no(page), mtr);
ibuf_bitmap_page_set_bits(bitmap_page, buf_frame_get_page_no(page), IBUF_BITMAP_FREE, val, mtr);
}
/*设置指定page的ibuf bitmap(page的空闲剩余长度)，mtr对象是在函数中自建的*/
void ibuf_set_free_bits(ulint type, page_t* page, ulint val, ulint max_val)
{
mtr_t mtr;
page_t* bitmap_page;
/*聚集索引，不能设置ibuf bitmap*/
if(type & DICT_CLUSTERED)
return;
if(btr_page_get_level_low(page) != 0)
return;
mtr_start(&mtr);
bitmap_page = ibuf_bitmap_get_map_page(buf_frame_get_space_id(page), buf_frame_get_page_no(page), &mtr);
if(max_val != ULINT_UNDEFINED){
}
ibuf_bitmap_page_set_bits(bitmap_page, buf_frame_get_page_no(page), IBUF_BITMAP_FREE, val, &mtr);
mtr_commit(&mtr);
}
/*重置指定page的ibuf bitmap(page剩余空间)*/
void ibuf_reset_free_bits_with_type(ulint type, page_t* page)
{
ibuf_set_free_bits(type, page, 0, ULINT_UNDEFINED);
}
/*与ibuf_reset_free_bits_with_type功能相同*/
void ibuf_reset_free_bits(dict_index_t* index, page_t* page)
{
ibuf_set_free_bits(index->type, page, 0, ULINT_UNDEFINED);
}
/*更新page的剩余空间信息到ibuf bitmap中,这个函数只会在记录乐观方式的时候调用*/
void ibuf_update_free_bits_low(dict_index_t* index, page_t* page, ulint max_ins_size, mtr_t* mtr)
{
ulint before;
ulint after;
/*获得max_ins_size对应剩余空间范围的序号*/
before = ibuf_index_page_calc_free_bits(max_ins_size);
/*获得page剩余空间的范围序号*/
after = ibuf_index_page_calc_free(page);
/*重设page对应的bitmap中剩余空间的信息*/
if(after != before)
ibuf_set_free_bits_low(index->type, page, after, mtr);
}
/*同时更新两个page的ibuf bitmap,这个函数只会在btree分裂的时候调用*/
UNIV_INLINE ibool ibuf_update_free_bits_for_two_pages_low(dict_index_t* index, page_t* page1, page_t* page2, mtr_t* mtr)
{
ulint state;
/* As we have to x-latch two random bitmap pages, we have to acquire
the bitmap mutex to prevent a deadlock with a similar operation
performed by another OS thread. 防止其他线程类似的操作造成死锁？？*/
mutex_enter(&ibuf_bitmap_mutex);
state = ibuf_index_page_calc_free(page1);
ibuf_set_free_bits_low(index->type, page1, state, mtr);
state = ibuf_set_free_bits_low(page2);
ibuf_set_free_bits_low(index->type, page2, state, mtr);
mutex_exit(&ibuf_bitmap_mutex);
}
/*判断page_no对应的page是否是ibuf固定的page(bitmap page / root page)*/
UNIV_INLINE ibool ibuf_fixed_addr_page(ulint page_no)
{
/*page_no对应的page是ibuf bitmap page或者ibuf root page*/
if(ibuf_bitmap_page(page_no) || page_no == IBUF_TREE_ROOT_PAGE_NO)
return TRUE;
return FALSE;
}
/*检查指定的page是否是ibuf btree的索引页，不是叶子节点*/
ibool ibuf_page(ulint space, ulint page_no)
{
page_t* bitmap_page;
mtr_t mtr;
ibool ret;
/*正在redo log重演*/
if(recv_no_ibuf_operations)
return FALSE;
if(ibuf_fixed_addr_page(page_no))
return TRUE;
ut_ad(fil_space_get_type(space) == FIL_TABLESPACE);
mtr_start(&mtr);
bitmap_page = ibuf_bitmap_get_map_page(space, page_no, &mtr);
/*获得bitmap的第4位的标识*/
ret = ibuf_bitmap_page_get_bits(bitmap_page, page_no, IBUF_BITMAP_IBUF, &mtr);
mtr_commit(&mtr);
return ret;
}
/*检查指定的page是否是ibuf btree的索引页，不是叶子节点,指定了mtr*/
ibool ibuf_page_low(ulint space, ulint page_no, mtr_t* mtr)
{
page_t* bitmap_page;
ibool ret;
if(ibuf_fixed_addr_page(page_no))
return TRUE;
bitmap_page = ibuf_bitmap_get_map_page(space, page_no, mtr);
ret = ibuf_bitmap_page_get_bits(bitmap_page, page_no, IBUF_BITMAP_IBUF, mtr);
return ret;
}
/*从ibuf rec中取得page no,可对照ibuf_data_init_for_space的建表过程*/
static ulint ibuf_rec_get_page_no(rec_t* rec)
{
byte* field;
ulint len;
ut_ad(ibuf_inside());
ut_ad(rec_get_n_fields(rec) > 2);
field = rec_get_nth_field(rec, 0, &len);
ut_ad(len == 4);
return mach_read_from_4(field);
}
/*计算得到一条ibuf_rec记录占用的空间大小*/
static ulint ibuf_rec_get_volume(rec_t* ibuf_rec)
{
dtype_t dtype;
ulint data_size = 0;
ulint n_fields;
byte* types;
byte* data;
ulint len;
ulint i;
ut_ad(ibuf_inside());
ut_ad(rec_get_n_fields(ibuf_rec) > 2);
n_fields = rec_get_n_fields(ibuf_rec) - 2;
/*获得记录中的types*/
types = rec_get_nth_field(ibuf_rec, 1, &len);
ut_ad(len == n_fields * DATA_ORDER_NULL_TYPE_BUF_SIZE);
for(i = 0; i < n_fields; i ++){
data = rec_get_nth_field(ibuf_rec, i + 2, &len);
dtype_read_for_order_and_null_size(&dtype, types + i * DATA_ORDER_NULL_TYPE_BUF_SIZE);
if(len == UNIV_SQL_NULL)
data_size += dtype_get_sql_null_size(&dtype);
else
data_size += len;
}
return data_size + rec_get_converted_extra_size(data_size, n_fields) + page_dir_calc_reserved_space(1);
}
/*依据tuple entry构建一个ibuf 的逻辑记录tuple_t*/
static dtuple_t* ibuf_entry_build(dtuple_t* entry, ulint page_no, mem_heap_t* heap)
{
dtuple_t* tuple;
dfield_t* field;
dfield_t* entry_field;
ulint n_fields;
byte* buf;
byte* buf2;
ulint i;
n_fields = dtuple_get_n_fields(entry);
/*建立一个内存逻辑记录*/
tuple = dtuple_create(heap, n_fields + 2);
field = dtuple_get_nth_field(tuple, 0);
/*写入page no到第一列中*/
buf = mem_heap_alloc(heap, 4);
mach_write_to_4(buf, page_no);
dfield_set_data(field, buf, 4);
buf2 = mem_heap_alloc(heap, n_fields * DATA_ORDER_NULL_TYPE_BUF_SIZE);
for (i = 0; i < n_fields; i++) {
/*将entry 中的值全部拷贝到tuple中*/
field = dtuple_get_nth_field(tuple, i + 2);
entry_field = dtuple_get_nth_field(entry, i);
dfield_copy(field, entry_field);
dtype_store_for_order_and_null_size(buf2 + i * DATA_ORDER_NULL_TYPE_BUF_SIZE, dfield_get_type(entry_field));
}
/*写入types*/
field = dtuple_get_nth_field(tuple, 1);
dfield_set_data(field, buf2, n_fields * DATA_ORDER_NULL_TYPE_BUF_SIZE);
/*全部设置成DATA_BINARY类型*/
dtuple_set_types_binary(tuple, n_fields + 2);
return tuple;
}
/*根据ibuf rec的物理记录转化成一个dtuple*/
static dtuple_t* ibuf_build_entry_from_ibuf_rec(rec_t* ibuf_rec, mem_heap_t* heap)
{
dtuple_t* tuple;
dfield_t* field;
ulint n_fields;
byte* types;
byte* data;
ulint len;
ulint i;
n_fields = rec_get_n_fields(ibuf_rec) - 2;
tuple = dtuple_create(heap, n_fields);
types = rec_get_nth_field(ibuf_rec, 1, &len);
ut_ad(len == n_fields * DATA_ORDER_NULL_TYPE_BUF_SIZE);
for(i = 0; i < n_fields; i ++){
field = dtuple_get_nth_field(tuple, i);
data = rec_get_nth_field(ibuf_rec, i + 2, &len);
dfield_set_data(field, data, len);
dtype_read_for_order_and_null_size(dfield_get_type(field), types + i * DATA_ORDER_NULL_TYPE_BUF_SIZE);
}
return tuple;
}
/*构建一个存储有page no用于search的tuple*/
static dtuple_t* ibuf_search_tuple_build(ulint page_no, mem_heap_t* heap)
{
dtuple_t* tuple;
dfield_t* field;
byte* buf;
tuple = dtuple_create(heap, 1);
field = dtuple_get_nth_field(tuple, 0);
buf = mem_heap_alloc(heap, 4);
mach_write_to_4(buf, page_no);
dfield_set_data(field, buf, 4);
dtuple_set_types_binary(tuple, 1);
}
/*检查data->free_list_len是否有足够的page*/
UNIV_INLINE ibool ibuf_data_enough_free_for_insert(ibuf_data_t* data)
{
ut_ad(mutex_own(&ibuf_mutex));
if(data->free_list_len >= data->size / 2 + 3 * data->height)
return TRUE;
return FALSE;
}
/*检查data->free_list_len，如果空闲的page太多，删除一些page并从tablespace中剔除*/
UNIV_INLINE ibool ibuf_data_too_much_free(ibuf_data_t* data)
{
ut_ad(mutex_own(&ibuf_mutex));
if (data->free_list_len >= 3 + data->size / 2 + 3 * data->height)
return TRUE;
return FALSE;
}
/*为ibuf_data分配一个新的page空间*/
static ulint ibuf_add_free_page(ulint space, ibuf_data_t* ibuf_data)
{
mtr_t mtr;
page_t* header_page;
ulint page_no;
page_t* page;
page_t* root;
page_t* bitmap_page;
mtr_start(&mtr);
mtr_x_lock(fil_space_get_latch(space), &mtr);
/*从fil space中分配一个page*/
header_page = ibuf_header_page_get(space, &mtr);
page_no = fseg_alloc_free_page(header_page + IBUF_HEADER + IBUF_TREE_SEG_HEADER, 0, FSP_UP, &mtr);
if(page_no == FIL_NULL){
mtr_commit(&mtr);
return DB_STRONG_FAIL;
}
/*在缓冲池中获得page的内存指针*/
page = buf_page_get(space, page_no, RW_X_LATCH, &mtr);
buf_page_dbg_add_level(page, SYNC_TREE_NODE_NEW);
ibuf_enter();
mutex_enter();
root = ibuf_tree_root_get(ibuf_data, space, &mtr);
/*将新分配的page加入到root page free当中*/
flst_add_last(root + PAGE_HEADER + PAGE_BTR_IBUF_FREE_LIST, page + PAGE_HEADER + PAGE_BTR_IBUF_FREE_LIST_NODE, &mtr);
ibuf_data->seg_size ++;
ibuf_data->free_list_len ++;
/*设置page对应ibuf bitmap上的状态信息*/
bitmap_page = ibuf_bitmap_get_map_page(space, page_no, &mtr);
ibuf_bitmap_page_set_bits(bitmap_page, page_no, IBUF_BITMAP_IBUF, TRUE, &mtr);
mtr_commit(&mtr);
mutex_exit(&ibuf_mutex);
ibuf_exit();
return DB_SUCCESS;
}
/*将一个空闲page从ibuf_data中删除并回收对应的表空间*/
static void ibuf_remove_free_page(ulint space, ibuf_data_t* ibuf_data)
{
mtr_t mtr;
mtr_t mtr2;
page_t* header_page;
ulint page_no;
page_t* page;
page_t* root;
page_t* bitmap_page;
mtr_start(&mtr);
mtr_x_lock(fil_space_get_latch(space), &mtr);
header_page = ibuf_header_page_get(space, &mtr);
mutex_enter(&ibuf_pessimistic_insert_mutex);
ibuf_enter();
mutex_enter(&ibuf_mutex);
/*ibuf_data中没有过多的page空闲，可以不是释放回收page*/
if(!ibuf_data_too_much_free(ibuf_data)){
mutex_exit(&ibuf_mutex);
ibuf_exit();
mutex_exit(&ibuf_pessimistic_insert_mutex);
mtr_commit(&mtr);
return;
}
/*启用另外一个mini transaction是为了防止死锁！*/
mtr_start(&mtr2);
root = ibuf_tree_root_get(ibuf_data, space, &mtr2);
/*获得root最后一个空闲页的page no*/
page_no = flst_get_last(root + PAGE_HEADER + PAGE_BTR_IBUF_FREE_LIST, &mtr2).page;
mtr_commit(&mtr2);
mutex_exit(&ibuf_mutex);
ibuf_exit();
/*对page进行表空间回收*/
fseg_free_page(header_page + IBUF_HEADER + IBUF_TREE_SEG_HEADER, space, page_no, &mtr);
ibuf_enter();
mutex_enter(&ibuf_mutex);
/*从root的free list将其删除*/
root = ibuf_tree_root_get(ibuf_data, space, &mtr);
ut_ad(page_no == flst_get_last(root + PAGE_HEADER + PAGE_BTR_IBUF_FREE_LIST, &mtr).page);
page = buf_page_get(space, page_no, RW_X_LATCH, &mtr);
buf_page_dbg_add_level(page, SYNC_TREE_NODE);
flst_remove(root + PAGE_HEADER + PAGE_BTR_IBUF_FREE_LIST, page + PAGE_HEADER + PAGE_BTR_IBUF_FREE_LIST_NODE, &mtr);
ibuf_data->seg_size --;
ibuf_data->free_list_len --;
mutex_exit(&ibuf_pessimistic_insert_mutex);
/*将ibuf bitmap中的状态设置为page没有被ibuf缓冲*/
bitmap_page = ibuf_bitmap_get_map_page(space, page_no, &mtr);
ibuf_bitmap_page_set_bits(bitmap_page, page_no, IBUF_BITMAP_IBUF, FALSE, &mtr);
mtr_commit(&mtr);
mutex_exit(&ibuf_mutex);
ibuf_exit();
}
/*释放space对应的ibuf_data中过剩的page,每次调用这个函数会释放4个page,在表空间分配页的时候会调用此函数*/
void ibuf_free_excess_pages(ulint space)
{
ibuf_data_t* ibuf_data;
ulint i;
ut_ad(rw_lock_own(fil_space_get_latch(space), RW_LOCK_EX));
ut_ad(rw_lock_get_x_lock_count(fil_space_get_latch(space)) == 1);
ut_ad(!ibuf_inside());
/*对应表空间无ibuf_data*/
ibuf_data = fil_space_get_ibuf_data(space);
if(ibuf_data == NULL)
return ;
/*连续释放4个page*/
for(i = 0; i < 4; i ++){
mutex_enter(&ibuf_mutex);
if (!ibuf_data_too_much_free(ibuf_data)){
mutex_exit(&ibuf_mutex);
return;
}
mutex_exit(&ibuf_mutex);
ibuf_remove_free_page(space, ibuf_data);
}
}
/*从ibuf tree的叶子page的记录中获得合并的page nos*/
static ulint ibuf_get_merge_page_nos(ibool contract, rec_t* first_rec, ulint* page_nos, ulint* n_stored)
{
ulint prev_page_no;
ulint first_page_no;
ulint rec_page_no;
rec_t* rec;
ulint sum_volumes;
ulint volume_for_page;
ulint rec_volume;
ulint limit;
page_t* page;
ulint n_pages;
*n_stored = 0;
limit = ut_min(IBUF_MAX_N_PAGES_MERGED, buf_pool->curr_size / 4);
page = uf_frame_align(first_rec);
if(first_rec == page_get_supremum_rec(page))
first_rec = page_rec_get_prev(first_rec);
if(first_rec == page_get_infimum_rec(page))
first_rec = page_rec_get_next(first_rec);
/*这一页无记录*/
if (first_rec == page_get_supremum_rec(page))
return(0);
rec = first_rec;
first_page_no = ibuf_rec_get_page_no(first_rec);
n_pages = 0;
prev_page_no = 0;
/*定位到以8个page为单位的范围最前面一条记录*/
while(rec != page_get_infimum_rec(page) && n_pages < limit){
rec_page_no = ibuf_rec_get_page_no(rec);
ut_ad(rec_page_no != 0);
/*与first page同时处于8个page为单位的范围之中*/
if(rec_page_no / IBUF_MERGE_AREA != first_page_no / IBUF_MERGE_AREA)
break;
if(rec_page_no != prev_page_no)
n_pages ++;
prev_page_no = rec_page_no;
rec = page_rec_get_prev(rec);
}
rec = page_rec_get_next(rec);
prev_page_no = 0;
sum_volumes = 0;
volume_for_page = 0;
while(*n_stored < limit){
if(rec == page_get_supremum_rec(page))
rec_page_no = 1;
else{
rec_page_no = ibuf_rec_get_page_no(rec);
ut_ad(rec_page_no > IBUF_TREE_ROOT_PAGE_NO);
}
if(rec_page_no != prev_page_no){
/*如果rec对应的page是first_page_no或者记录空间达到了merge的阈值,那么这个page将作为合并的目的page??*/
if(prev_page_no == first_page_no || contract ||
volume_for_page > (((IBUF_MERGE_THRESHOLD - 1) * 4 * UNIV_PAGE_SIZE / IBUF_PAGE_SIZE_PER_FREE_SPACE)/ IBUF_MERGE_THRESHOLD)){
page_nos[*n_stored] = prev_page_no;
(*n_stored) ++;
sum_volumes += volume_for_page;
}
if(rec_page_no / IBUF_MERGE_AREA != first_page_no / IBUF_MERGE_AREA)
break;
volume_for_page = 0;
}
if(rec_page_no == 1) /*直接到了supremum记录，退出循环*/
break;
rec_volume = ibuf_rec_get_volume(rec);
volume_for_page += rec_volume;
prev_page_no = rec_page_no;
rec = page_rec_get_next(rec);
}
return sum_volumes;
}
/*由于buffer pool内存上限导致收缩ibuf btree*/
static ulint ibuf_contract_ext(ulint* n_pages, ibool sync)
{
ulint rnd_pos;
ibuf_data_t* data;
btr_pcur_t pcur;
ulint space;
ibool all_trees_empty;
ulint page_nos[IBUF_MAX_N_PAGES_MERGED];
ulint n_stored;
ulint sum_sizes;
mtr_t mtr;
*n_pages = 0;
loop:
ut_ad(!ibuf_inside());
mutex_enter(&ibuf_mutex);
ut_ad(ibuf_validate_low());
/*随机获得一个位置*/
ibuf_rnd = 865558671;
rnd_pos = ibuf_rnd % ibuf->size;
all_trees_empty = TRUE;
/*定位contract的ibuf_data位置*/
data = UT_LIST_GET_FIRST(ibuf->data_list);
for(;;){
if(!data->empty){
all_trees_empty = FALSE;
if(rnd_pos < data->size)
break;
rnd_pos -= data->size;
}
data = UT_LIST_GET_NEXT(data_list, data);
if(data == NULL){ /*没有随机位置data size合并点*/
if(all_trees_empty){
mutex_exit(&ibuf_mutex);
return 0;
}
data = UT_LIST_GET_FIRST(ibuf->data_list);
}
}
ut_ad(data);
space = data->index->space;
mtr_start(&mtr);
ibuf_enter();
/*打开btree上随机定位到的BTREE 操作游标*/
btr_pcur_open_at_rnd_pos(data->index, BTR_SEARCH_LEAF, &pcur, &mtr);
if(0 == page_get_n_recs(btr_pcur_get_page(&pcur))){ /*定位到的page没有任何的用户记录,无法merge page*/