#include <buf0buf.h>
Data Fields | |
General fields | |
| buf_page_t | page |
| byte * | frame |
| ut_list_node< buf_block_t > | unzip_LRU |
| ibool | in_unzip_LRU_list |
| ib_mutex_t | mutex |
| rw_lock_t | lock |
| unsigned | lock_hash_val:32 |
| ibool | check_index_page_at_flush |
Optimistic search field | |
| ib_uint64_t | modify_clock |
Hash search fields (unprotected) | |
NOTE that these fields are NOT protected by any semaphore! | |
| ulint | n_hash_helps |
| ulint | n_fields |
| ulint | n_bytes |
| ibool | left_side |
Hash search fields | |
These 5 fields may only be modified when we have an x-latch on btr_search_latch AND
An exception to this is when we init or create a page in the buffer pool in buf0buf.cc. Another exception is that assigning block->index = NULL is allowed whenever holding an x-latch on btr_search_latch. | |
| ulint | n_pointers |
| unsigned | curr_n_fields:10 |
| unsigned | curr_n_bytes:15 |
| unsigned | curr_left_side:1 |
| dict_index_t * | index |
Debug fields | |
| rw_lock_t | debug_latch |
Detailed Description
The buffer control block structure
Field Documentation
| ibool buf_block_t::check_index_page_at_flush |
TRUE if we know that this is an index page, and want the database to check its consistency before flush; note that there may be pages in the buffer pool which are index pages, but this flag is not set because we do not keep track of all pages; NOT protected by any mutex
| unsigned buf_block_t::curr_left_side |
TRUE or FALSE in hash indexing
| unsigned buf_block_t::curr_n_bytes |
number of bytes in hash indexing
| unsigned buf_block_t::curr_n_fields |
prefix length for hash indexing: number of full fields
| rw_lock_t buf_block_t::debug_latch |
in the debug version, each thread which bufferfixes the block acquires an s-latch here; so we can use the debug utilities in sync0rw
| byte* buf_block_t::frame |
pointer to buffer frame which is of size UNIV_PAGE_SIZE, and aligned to an address divisible by UNIV_PAGE_SIZE
| ibool buf_block_t::in_unzip_LRU_list |
TRUE if the page is in the decompressed LRU list; used in debugging
| dict_index_t* buf_block_t::index |
Index for which the adaptive hash index has been created, or NULL if the page does not exist in the index. Note that it does not guarantee that the index is complete, though: there may have been hash collisions, record deletions, etc.
| ibool buf_block_t::left_side |
TRUE or FALSE, depending on whether the leftmost record of several records with the same prefix should be indexed in the hash index
| rw_lock_t buf_block_t::lock |
read-write lock of the buffer frame
| unsigned buf_block_t::lock_hash_val |
hashed value of the page address in the record lock hash table; protected by buf_block_t::lock (or buf_block_t::mutex, buf_pool->mutex in buf_page_get_gen(), buf_page_init_for_read() and buf_page_create())
| ib_uint64_t buf_block_t::modify_clock |
this clock is incremented every time a pointer to a record on the page may become obsolete; this is used in the optimistic cursor positioning: if the modify clock has not changed, we know that the pointer is still valid; this field may be changed if the thread (1) owns the pool mutex and the page is not bufferfixed, or (2) the thread has an x-latch on the block
| ib_mutex_t buf_block_t::mutex |
mutex protecting this block: state (also protected by the buffer pool mutex), io_fix, buf_fix_count, and accessed; we introduce this new mutex in InnoDB-5.1 to relieve contention on the buffer pool mutex
| ulint buf_block_t::n_bytes |
recommended prefix: number of bytes in an incomplete field
| ulint buf_block_t::n_fields |
recommended prefix length for hash search: number of full fields
| ulint buf_block_t::n_hash_helps |
counter which controls building of a new hash index for the page
| ulint buf_block_t::n_pointers |
used in debugging: the number of pointers in the adaptive hash index pointing to this frame
| buf_page_t buf_block_t::page |
page information; this must be the first field, so that buf_pool->page_hash can point to buf_page_t or buf_block_t
| ut_list_node< buf_block_t > buf_block_t::unzip_LRU |
node of the decompressed LRU list; a block is in the unzip_LRU list if page.state == BUF_BLOCK_FILE_PAGE and page.zip.data != NULL
The documentation for this struct was generated from the following file:
- include/buf0buf.h
