trx0i_s.cc File Reference

INFORMATION SCHEMA innodb_trx, innodb_locks and innodb_lock_waits tables fetch code. More...

#include <sql_class.h>
#include <stdio.h>
#include "buf0buf.h"
#include "dict0dict.h"
#include "ha0storage.h"
#include "ha_prototypes.h"
#include "hash0hash.h"
#include "lock0iter.h"
#include "lock0lock.h"
#include "mem0mem.h"
#include "mysql/plugin.h"
#include "page0page.h"
#include "rem0rec.h"
#include "row0row.h"
#include "srv0srv.h"
#include "sync0rw.h"
#include "sync0sync.h"
#include "trx0i_s.h"
#include "trx0sys.h"
#include "trx0trx.h"
#include "ut0mem.h"
#include "storage/perfschema/pfs_data_lock.h"

Classes
struct	i_s_mem_chunk_t
	Memory for each table in the intermediate buffer is allocated in separate chunks. More...
struct	i_s_table_cache_t
	This represents one table's cache. More...
struct	trx_i_s_cache_t
	This structure describes the intermediate buffer. More...

Macros
#define	MAX_ALLOWED_FOR_STORAGE(cache)   (TRX_I_S_MEM_LIMIT - (cache)->mem_allocd)
	Memory limit passed to ha_storage_put_memlim(). More...
#define	MAX_ALLOWED_FOR_ALLOC(cache)
	Memory limit in table_cache_create_empty_row(). More...

Functions
static ulint	wait_lock_get_heap_no (const lock_t *lock)
	For a record lock that is in waiting state retrieves the only bit that is set, for a table lock returns ULINT_UNDEFINED. More...
static void	table_cache_init (i_s_table_cache_t *table_cache, size_t row_size)
	Initializes the members of a table cache. More...
static void	table_cache_free (i_s_table_cache_t *table_cache)
	Frees a table cache. More...
static void *	table_cache_create_empty_row (i_s_table_cache_t *table_cache, trx_i_s_cache_t *cache)
	Returns an empty row from a table cache. More...
static bool	i_s_locks_row_validate (const i_s_locks_row_t *row)
	Validates a row in the locks cache. More...
static bool	fill_trx_row (i_s_trx_row_t *row, const trx_t *trx, const i_s_locks_row_t *requested_lock_row, trx_i_s_cache_t *cache)
	Fills i_s_trx_row_t object. More...
static ulint	put_nth_field (char *buf, ulint buf_size, ulint n, const dict_index_t *index, const rec_t *rec, const ulint *offsets)
	Format the nth field of "rec" and put it in "buf". More...
void	p_s_fill_lock_data (const char **lock_data, const lock_t *lock, ulint heap_no, PSI_server_data_lock_container *container)
	Fill performance schema lock data. More...
void	fill_locks_row (i_s_locks_row_t *row, const lock_t *lock, ulint heap_no)
	Fills i_s_locks_row_t object with data about the lock. More...
static i_s_locks_row_t *	add_lock_to_cache (trx_i_s_cache_t *cache, const lock_t *lock, ulint heap_no)
	Adds new element to the locks cache, enlarging it if necessary. More...
static bool	add_trx_relevant_locks_to_cache (trx_i_s_cache_t *cache, const trx_t *trx, i_s_locks_row_t **requested_lock_row)
	Adds transaction's relevant (important) locks to cache. More...
static bool	can_cache_be_updated (trx_i_s_cache_t *cache)
	Checks if the cache can safely be updated. More...
static void	trx_i_s_cache_clear (trx_i_s_cache_t *cache)
	Declare a cache empty, preparing it to be filled up. More...
template<typename Trx_list >
static void	fetch_data_into_cache_low (trx_i_s_cache_t *cache, Trx_list *trx_list)
	Fetches the data needed to fill the 3 INFORMATION SCHEMA tables into the table cache buffer. More...
static void	fetch_data_into_cache (trx_i_s_cache_t *cache)
	Fetches the data needed to fill the 3 INFORMATION SCHEMA tables into the table cache buffer. More...
int	trx_i_s_possibly_fetch_data_into_cache (trx_i_s_cache_t *cache)
	Update the transactions cache if it has not been read for some time. More...
bool	trx_i_s_cache_is_truncated (trx_i_s_cache_t *cache)
	Returns true if the data in the cache is truncated due to the memory limit posed by TRX_I_S_MEM_LIMIT. More...
void	trx_i_s_cache_init (trx_i_s_cache_t *cache)
	Initialize INFORMATION SCHEMA trx related cache. More...
void	trx_i_s_cache_free (trx_i_s_cache_t *cache)
	Free the INFORMATION SCHEMA trx related cache. More...
void	trx_i_s_cache_start_read (trx_i_s_cache_t *cache)
	Issue a shared/read lock on the tables cache. More...
void	trx_i_s_cache_end_read (trx_i_s_cache_t *cache)
	Release a shared/read lock on the tables cache. More...
void	trx_i_s_cache_start_write (trx_i_s_cache_t *cache)
	Issue an exclusive/write lock on the tables cache. More...
void	trx_i_s_cache_end_write (trx_i_s_cache_t *cache)
	Release an exclusive/write lock on the tables cache. More...
static i_s_table_cache_t *	cache_select_table (trx_i_s_cache_t *cache, enum i_s_table table)
	Selects a INFORMATION SCHEMA table cache from the whole cache. More...
ulint	trx_i_s_cache_get_rows_used (trx_i_s_cache_t *cache, enum i_s_table table)
	Retrieves the number of used rows in the cache for a given INFORMATION SCHEMA table. More...
void *	trx_i_s_cache_get_nth_row (trx_i_s_cache_t *cache, enum i_s_table table, ulint n)
	Retrieves the nth row (zero-based) in the cache for a given INFORMATION SCHEMA table. More...
char *	trx_i_s_create_lock_id (const i_s_locks_row_t *row, char *lock_id, ulint lock_id_size)
	Crafts a lock id string from a i_s_locks_row_t object. More...
int	trx_i_s_parse_lock_id (const char *lock_id, i_s_locks_row_t *row)
	Parses lock id into row. More...

Variables
constexpr uint32_t	TABLE_CACHE_INITIAL_ROWSNUM = 1024
	Initial number of rows in the table cache. More...
constexpr uint32_t	MEM_CHUNKS_IN_TABLE_CACHE = 39
	The maximum number of chunks to allocate for a table cache. More...
constexpr uint32_t	CACHE_STORAGE_INITIAL_SIZE = 1024
	Initial size of the cache storage. More...
constexpr uint32_t	CACHE_STORAGE_HASH_CELLS = 2048
	Number of hash cells in the cache storage. More...
static trx_i_s_cache_t	trx_i_s_cache_static
	This is the intermediate buffer where data needed to fill the INFORMATION SCHEMA tables is fetched and later retrieved by the C++ code in handler/i_s.cc. More...
trx_i_s_cache_t *	trx_i_s_cache = &trx_i_s_cache_static
	This is the intermediate buffer where data needed to fill the INFORMATION SCHEMA tables is fetched and later retrieved by the C++ code in handler/i_s.cc. More...
constexpr const char *	LOCK_RECORD_ID_FORMAT
constexpr const char *	LOCK_TABLE_ID_FORMAT = UINT64PF ":" UINT64PF ":" UINT64PF

Detailed Description

INFORMATION SCHEMA innodb_trx, innodb_locks and innodb_lock_waits tables fetch code.

The code below fetches information needed to fill those 3 dynamic tables and uploads it into a "transactions table cache" for later retrieval.

Created July 17, 2007 Vasil Dimov

Macro Definition Documentation

MAX_ALLOWED_FOR_ALLOC

#define MAX_ALLOWED_FOR_ALLOC

(

cache

)

Value:

  (TRX_I_S_MEM_LIMIT - (cache)->mem_allocd - \
   ha_storage_get_size((cache)->storage))

Memory limit in table_cache_create_empty_row().

Parameters

cache

hash storage

Returns

maximum allowed allocation size

MAX_ALLOWED_FOR_STORAGE

#define MAX_ALLOWED_FOR_STORAGE

(

cache

)

(TRX_I_S_MEM_LIMIT - (cache)->mem_allocd)

Memory limit passed to ha_storage_put_memlim().

Parameters

cache

hash storage

Returns

maximum allowed allocation size

Function Documentation

add_lock_to_cache()

static i_s_locks_row_t * add_lock_to_cache ( trx_i_s_cache_t *  cache, const lock_t *  lock, ulint  heap_no  )

static

Adds new element to the locks cache, enlarging it if necessary.

Returns a pointer to the added row. If the row is already present then no row is added and a pointer to the existing row is returned. If row can not be allocated then NULL is returned.

Returns

row

Parameters

cache	in/out: cache
lock	in: the element to add
heap_no	in: lock's record number or ULINT_UNDEFINED if the lock is a table lock

add_trx_relevant_locks_to_cache()

static bool add_trx_relevant_locks_to_cache ( trx_i_s_cache_t *  cache, const trx_t *  trx, i_s_locks_row_t **  requested_lock_row  )

static

Adds transaction's relevant (important) locks to cache.

If the transaction is waiting, then the wait lock is added to innodb_locks and a pointer to the added row is returned in requested_lock_row, otherwise requested_lock_row is set to NULL. If rows can not be allocated then false is returned and the value of requested_lock_row is undefined.

Returns

false if allocation fails

Parameters

cache	in/out: cache
trx	in: transaction
requested_lock_row	out: pointer to the requested lock row, or NULL or undefined

cache_select_table()

static i_s_table_cache_t * cache_select_table ( trx_i_s_cache_t *  cache, enum i_s_table  table  )

static

Selects a INFORMATION SCHEMA table cache from the whole cache.

Returns

table cache

Parameters

cache	in: whole cache
table	in: which table

can_cache_be_updated()

static bool can_cache_be_updated ( trx_i_s_cache_t *  cache )

static

Checks if the cache can safely be updated.

Returns

true if can be updated

The minimum time that a cache must not be updated after it has been read for the last time. We use this technique to ensure that SELECTs which join several INFORMATION SCHEMA tables read the same version of the cache.

Parameters

cache

in: cache

fetch_data_into_cache()

static void fetch_data_into_cache ( trx_i_s_cache_t *  cache )

static

Fetches the data needed to fill the 3 INFORMATION SCHEMA tables into the table cache buffer.

Cache must be locked for write.

Parameters

cache

in/out: cache

fetch_data_into_cache_low()

template<typename Trx_list >

static void fetch_data_into_cache_low ( trx_i_s_cache_t *  cache, Trx_list *  trx_list  )

static

Fetches the data needed to fill the 3 INFORMATION SCHEMA tables into the table cache buffer.

Cache must be locked for write.

Parameters

[in,out]	cache	the cache
[in]	trx_list	the list to scan

fill_locks_row()

void fill_locks_row	(	i_s_locks_row_t *	row,
		const lock_t *	lock,
		ulint	heap_no
	)

Fills i_s_locks_row_t object with data about the lock.

Parameters

[out]	row	Result object that's filled
[in]	lock	Lock to get data from
[in]	heap_no	Lock's record number or ULINT_UNDEFINED if the lock is a table lock

fill_trx_row()

static bool fill_trx_row ( i_s_trx_row_t *  row, const trx_t *  trx, const i_s_locks_row_t *  requested_lock_row, trx_i_s_cache_t *  cache  )

static

Fills i_s_trx_row_t object.

If memory can not be allocated then false is returned.

Returns

false if allocation fails

Parameters

row	out: result object that's filled
trx	in: transaction to get data from
requested_lock_row	in: pointer to the corresponding row in innodb_locks if trx is waiting or NULL if trx is not waiting
cache	in/out: cache into which to copy volatile strings

i_s_locks_row_validate()

static bool i_s_locks_row_validate ( const i_s_locks_row_t *  row )

static

Validates a row in the locks cache.

Returns

true if valid

Parameters

row	in: row to validate

p_s_fill_lock_data()

void p_s_fill_lock_data	(	const char **	lock_data,
		const lock_t *	lock,
		ulint	heap_no,
		PSI_server_data_lock_container *	container
	)

Fill performance schema lock data.

Create a string that represents the LOCK_DATA column, for a given lock record.

Parameters

[out]	lock_data	Lock data string
[in]	lock	Lock to inspect
[in]	heap_no	Lock heap number
[in]	container	Data container to fill

put_nth_field()

static ulint put_nth_field ( char *  buf, ulint  buf_size, ulint  n, const dict_index_t *  index, const rec_t *  rec, const ulint *  offsets  )

static

Format the nth field of "rec" and put it in "buf".

The result is always NUL-terminated. Returns the number of bytes that were written to "buf" (including the terminating NUL).

Returns

end of the result

Parameters

buf	out: buffer
buf_size	in: buffer size in bytes
n	in: number of field
index	in: index
rec	in: record
offsets	in: record offsets, returned by rec_get_offsets()

table_cache_create_empty_row()

static void * table_cache_create_empty_row ( i_s_table_cache_t *  table_cache, trx_i_s_cache_t *  cache  )

static

Returns an empty row from a table cache.

The row is allocated if no more empty rows are available. The number of used rows is incremented. If the memory limit is hit then NULL is returned and nothing is allocated.

Returns

empty row, or NULL if out of memory

Parameters

table_cache	in/out: table cache
cache	in/out: cache to record how many bytes are allocated

table_cache_free()

static void table_cache_free ( i_s_table_cache_t *  table_cache )

static

Frees a table cache.

Parameters

table_cache

in/out: table cache

table_cache_init()

static void table_cache_init ( i_s_table_cache_t *  table_cache, size_t  row_size  )

static

Initializes the members of a table cache.

Parameters

table_cache	out: table cache
row_size	in: the size of a row

trx_i_s_cache_clear()

static void trx_i_s_cache_clear ( trx_i_s_cache_t *  cache )

static

Declare a cache empty, preparing it to be filled up.

Not all resources are freed because they can be reused.

Parameters

cache

out: cache to clear

trx_i_s_cache_end_read()

void trx_i_s_cache_end_read

(

trx_i_s_cache_t *

cache

)

Release a shared/read lock on the tables cache.

in: cache

Parameters

cache

in: cache

trx_i_s_cache_end_write()

void trx_i_s_cache_end_write

(

trx_i_s_cache_t *

cache

)

Release an exclusive/write lock on the tables cache.

in: cache

Parameters

cache

in: cache

trx_i_s_cache_free()

void trx_i_s_cache_free

(

trx_i_s_cache_t *

cache

)

Free the INFORMATION SCHEMA trx related cache.

in/out: cache to free

Parameters

cache

in, own: cache to free

trx_i_s_cache_get_nth_row()

void * trx_i_s_cache_get_nth_row	(	trx_i_s_cache_t *	cache,
		enum i_s_table	table,
		ulint	n
	)

Retrieves the nth row (zero-based) in the cache for a given INFORMATION SCHEMA table.

Retrieves the nth row in the cache for a given INFORMATION SCHEMA table.

Returns

row

Parameters

cache	in: cache
table	in: which table
n	in: row number

trx_i_s_cache_get_rows_used()

ulint trx_i_s_cache_get_rows_used	(	trx_i_s_cache_t *	cache,
		enum i_s_table	table
	)

Retrieves the number of used rows in the cache for a given INFORMATION SCHEMA table.

Returns

number of rows

Parameters

cache	in: cache
table	in: which table

trx_i_s_cache_init()

void trx_i_s_cache_init

(

trx_i_s_cache_t *

cache

)

Initialize INFORMATION SCHEMA trx related cache.

out: cache to init

Parameters

cache

out: cache to init

trx_i_s_cache_is_truncated()

bool trx_i_s_cache_is_truncated

(

trx_i_s_cache_t *

cache

)

Returns true if the data in the cache is truncated due to the memory limit posed by TRX_I_S_MEM_LIMIT.

Parameters

[in]

cache

The cache

Returns

true if truncated

trx_i_s_cache_start_read()

void trx_i_s_cache_start_read

(

trx_i_s_cache_t *

cache

)

Issue a shared/read lock on the tables cache.

in: cache

Parameters

cache

in: cache

trx_i_s_cache_start_write()

void trx_i_s_cache_start_write

(

trx_i_s_cache_t *

cache

)

Issue an exclusive/write lock on the tables cache.

in: cache

Parameters

cache

in: cache

trx_i_s_create_lock_id()

char * trx_i_s_create_lock_id	(	const i_s_locks_row_t *	row,
		char *	lock_id,
		ulint	lock_id_size
	)

Crafts a lock id string from a i_s_locks_row_t object.

Returns its second argument. This function aborts if there is not enough space in lock_id. Be sure to provide at least TRX_I_S_LOCK_ID_MAX_LEN + 1 if you want to be 100% sure that it will not abort.

Returns

resulting lock id

Parameters

row	in: innodb_locks row
lock_id	out: resulting lock_id
lock_id_size	in: size of the lock id buffer

trx_i_s_parse_lock_id()

int trx_i_s_parse_lock_id	(	const char *	lock_id,
		i_s_locks_row_t *	row
	)

Parses lock id into row.

Parameters

[in]	lock_id	Lock id generated with trx_i_s_create_lock_id
[out]	row	Row to be filled in with data

Returns

LOCK_REC, LOCK_TABLE or 0 if failed to parse

trx_i_s_possibly_fetch_data_into_cache()

int trx_i_s_possibly_fetch_data_into_cache

(

trx_i_s_cache_t *

cache

)

Update the transactions cache if it has not been read for some time.

Called from handler/i_s.cc.

Returns

0 - fetched, 1 - not

Parameters

cache

in/out: cache

wait_lock_get_heap_no()

static ulint wait_lock_get_heap_no ( const lock_t *  lock )

static

For a record lock that is in waiting state retrieves the only bit that is set, for a table lock returns ULINT_UNDEFINED.

Returns

record number within the heap

Parameters

lock

in: lock

Variable Documentation

CACHE_STORAGE_HASH_CELLS

constexpr uint32_t CACHE_STORAGE_HASH_CELLS = 2048

constexpr

Number of hash cells in the cache storage.

CACHE_STORAGE_INITIAL_SIZE

constexpr uint32_t CACHE_STORAGE_INITIAL_SIZE = 1024

constexpr

Initial size of the cache storage.

LOCK_RECORD_ID_FORMAT

constexpr const char* LOCK_RECORD_ID_FORMAT

constexpr

Initial value:

=
    UINT64PF ":" SPACE_ID_PF ":" PAGE_NO_PF ":" ULINTPF ":" UINT64PF

LOCK_TABLE_ID_FORMAT

constexpr const char* LOCK_TABLE_ID_FORMAT = UINT64PF ":" UINT64PF ":" UINT64PF

constexpr

MEM_CHUNKS_IN_TABLE_CACHE

constexpr uint32_t MEM_CHUNKS_IN_TABLE_CACHE = 39

constexpr

The maximum number of chunks to allocate for a table cache.

The rows of a table cache are stored in a set of chunks. When a new row is added a new chunk is allocated if necessary. Assuming that the first one is 1024 rows (TABLE_CACHE_INITIAL_ROWSNUM) and each subsequent is N/2 where N is the number of rows we have allocated till now, then 39th chunk would accommodate 1677416425 rows and all chunks would accommodate 3354832851 rows.

TABLE_CACHE_INITIAL_ROWSNUM

constexpr uint32_t TABLE_CACHE_INITIAL_ROWSNUM = 1024

constexpr

Initial number of rows in the table cache.

trx_i_s_cache

trx_i_s_cache_t* trx_i_s_cache = &trx_i_s_cache_static

This is the intermediate buffer where data needed to fill the INFORMATION SCHEMA tables is fetched and later retrieved by the C++ code in handler/i_s.cc.

trx_i_s_cache_static

trx_i_s_cache_t trx_i_s_cache_static

static

This is the intermediate buffer where data needed to fill the INFORMATION SCHEMA tables is fetched and later retrieved by the C++ code in handler/i_s.cc.