diff options
Diffstat (limited to 'storage/xtradb/include/buf0rea.h')
| -rw-r--r-- | storage/xtradb/include/buf0rea.h | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/storage/xtradb/include/buf0rea.h b/storage/xtradb/include/buf0rea.h index 4910c1e2aca..dedd1904d31 100644 --- a/storage/xtradb/include/buf0rea.h +++ b/storage/xtradb/include/buf0rea.h @@ -76,6 +76,32 @@ buf_read_page( ulint offset, /*!< in: page number */ trx_t* trx); /********************************************************************//** +Applies a random read-ahead in buf_pool if there are at least a threshold +value of accessed pages from the random read-ahead area. Does not read any +page, not even the one at the position (space, offset), if the read-ahead +mechanism is not activated. NOTE 1: the calling thread may own latches on +pages: to avoid deadlocks this function must be written such that it cannot +end up waiting for these latches! NOTE 2: the calling thread must want +access to the page given: this rule is set to prevent unintended read-aheads +performed by ibuf routines, a situation which could result in a deadlock if +the OS does not support asynchronous i/o. +@return number of page read requests issued; NOTE that if we read ibuf +pages, it may happen that the page at the given page number does not +get read even if we return a positive value! +@return number of page read requests issued */ +UNIV_INTERN +ulint +buf_read_ahead_random( +/*==================*/ + ulint space, /*!< in: space id */ + ulint zip_size, /*!< in: compressed page size in bytes, + or 0 */ + ulint offset, /*!< in: page number of a page which + the current thread wants to access */ + ibool inside_ibuf, /*!< in: TRUE if we are inside ibuf + routine */ + trx_t* trx); +/********************************************************************//** Applies linear read-ahead if in the buf_pool the page is a border page of a linear read-ahead area and all the pages in the area have been accessed. Does not read any page if the read-ahead mechanism is not activated. Note |