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MySQL 5.6.14 Source Code Document
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MySQL 5.6.14 Source Code Document
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#include "buf0rea.h"#include "fil0fil.h"#include "mtr0mtr.h"#include "buf0buf.h"#include "buf0flu.h"#include "buf0lru.h"#include "buf0dblwr.h"#include "ibuf0ibuf.h"#include "log0recv.h"#include "trx0sys.h"#include "os0file.h"#include "srv0start.h"#include "srv0srv.h"#include "mysql/plugin.h"#include "mysql/service_thd_wait.h"
Go to the source code of this file.
Macros | |
| #define | BUF_READ_AHEAD_RANDOM_THRESHOLD(b) (5 + BUF_READ_AHEAD_AREA(b) / 8) |
| #define | BUF_READ_AHEAD_PEND_LIMIT 2 |
Functions | |
| UNIV_INTERN ulint | buf_read_ahead_random (ulint space, ulint zip_size, ulint offset, ibool inside_ibuf) |
| UNIV_INTERN ibool | buf_read_page (ulint space, ulint zip_size, ulint offset) |
| UNIV_INTERN ibool | buf_read_page_async (ulint space, ulint offset) |
| UNIV_INTERN ulint | buf_read_ahead_linear (ulint space, ulint zip_size, ulint offset, ibool inside_ibuf) |
| UNIV_INTERN void | buf_read_ibuf_merge_pages (bool sync, const ulint *space_ids, const ib_int64_t *space_versions, const ulint *page_nos, ulint n_stored) |
| UNIV_INTERN void | buf_read_recv_pages (ibool sync, ulint space, ulint zip_size, const ulint *page_nos, ulint n_stored) |
| #define BUF_READ_AHEAD_PEND_LIMIT 2 |
If there are buf_pool->curr_size per the number below pending reads, then
read-ahead is not done: this is to prevent flooding the buffer pool with i/o-fixed buffer blocks
Definition at line 52 of file buf0rea.cc.
| #define BUF_READ_AHEAD_RANDOM_THRESHOLD | ( | b | ) | (5 + BUF_READ_AHEAD_AREA(b) / 8) |
There must be at least this many pages in buf_pool in the area to start
a random read-ahead
Definition at line 46 of file buf0rea.cc.
| UNIV_INTERN ulint buf_read_ahead_linear | ( | ulint | space, |
| ulint | zip_size, | ||
| ulint | offset, | ||
| ibool | inside_ibuf | ||
| ) |
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 that the algorithm looks at the 'natural' adjacent successor and predecessor of the page, which on the leaf level of a B-tree are the next and previous page in the chain of leaves. To know these, the page specified in (space, offset) must already be present in the buf_pool. Thus, the natural way to use this function is to call it when a page in the buf_pool is accessed the first time, calling this function just after it has been bufferfixed. NOTE 1: as this function looks at the natural predecessor and successor fields on the page, what happens, if these are not initialized to any sensible value? No problem, before applying read-ahead we check that the area to read is within the span of the space, if not, read-ahead is not applied. An uninitialized value may result in a useless read operation, but only very improbably. NOTE 2: 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 3: 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 io.
| space | in: space id |
| zip_size | in: compressed page size in bytes, or 0 |
| offset | in: page number; see NOTE 3 above |
| inside_ibuf | in: TRUE if we are inside ibuf routine |
Definition at line 498 of file buf0rea.cc.
| UNIV_INTERN ulint buf_read_ahead_random | ( | ulint | space, |
| ulint | zip_size, | ||
| ulint | offset, | ||
| ibool | inside_ibuf | ||
| ) |
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.
| space | in: space id |
| zip_size | in: compressed page size in bytes, or 0 |
| offset | in: page number of a page which the current thread wants to access |
| inside_ibuf | in: TRUE if we are inside ibuf routine |
Definition at line 237 of file buf0rea.cc.
| UNIV_INTERN void buf_read_ibuf_merge_pages | ( | bool | sync, |
| const ulint * | space_ids, | ||
| const ib_int64_t * | space_versions, | ||
| const ulint * | page_nos, | ||
| ulint | n_stored | ||
| ) |
Issues read requests for pages which the ibuf module wants to read in, in order to contract the insert buffer tree. Technically, this function is like a read-ahead function.
| sync | in: true if the caller wants this function to wait for the highest address page to get read in, before this function returns |
| space_ids | in: array of space ids |
| space_versions | in: the spaces must have this version number (timestamp), otherwise we discard the read; we use this to cancel reads if DISCARD + IMPORT may have changed the tablespace size |
| page_nos | in: array of page numbers to read, with the highest page number the last in the array |
| n_stored | in: number of elements in the arrays |
Definition at line 760 of file buf0rea.cc.
| UNIV_INTERN ibool buf_read_page | ( | ulint | space, |
| ulint | zip_size, | ||
| ulint | offset | ||
| ) |
High-level function which reads a page asynchronously from a file to the buffer buf_pool if it is not already there. Sets the io_fix flag and sets an exclusive lock on the buffer frame. The flag is cleared and the x-lock released by the i/o-handler thread.
| space | in: space id |
| zip_size | in: compressed page size in bytes, or 0 |
| offset | in: page number |
Definition at line 394 of file buf0rea.cc.
| UNIV_INTERN ibool buf_read_page_async | ( | ulint | space, |
| ulint | offset | ||
| ) |
High-level function which reads a page asynchronously from a file to the buffer buf_pool if it is not already there. Sets the io_fix flag and sets an exclusive lock on the buffer frame. The flag is cleared and the x-lock released by the i/o-handler thread.
| space | in: space id |
| offset | in: page number |
Definition at line 437 of file buf0rea.cc.
| UNIV_INTERN void buf_read_recv_pages | ( | ibool | sync, |
| ulint | space, | ||
| ulint | zip_size, | ||
| const ulint * | page_nos, | ||
| ulint | n_stored | ||
| ) |
Issues read requests for pages which recovery wants to read in.
| sync | in: TRUE if the caller wants this function to wait for the highest address page to get read in, before this function returns |
| space | in: space id |
| zip_size | in: compressed page size in bytes, or 0 |
| page_nos | in: array of page numbers to read, with the highest page number the last in the array |
| n_stored | in: number of page numbers in the array |
Definition at line 836 of file buf0rea.cc.
1.8.1.2