#include <table_cache.h>

Public Member Functions
bool	init ()
void	destroy ()
void	lock ()
void	unlock ()
void	assert_owner ()
TABLE *	get_table (THD thd, my_hash_value_type hash_value, const char key, uint key_length, TABLE_SHARE **share)
void	release_table (THD thd, TABLE table)
bool	add_used_table (THD thd, TABLE table)
void	remove_table (TABLE *table)
uint	cached_tables () const
void	free_all_unused_tables ()
void	print_tables ()

Static Public Member Functions
static void	init_psi_keys ()

Detailed Description

Cache for open TABLE objects.

The idea behind this cache is that most statements don't need to go to a central table definition cache to get a TABLE object and therefore don't need to lock LOCK_open mutex. Instead they only need to go to one Table_cache instance (the specific instance is determined by thread id) and only lock the mutex protecting this cache. DDL statements that need to remove all TABLE objects from all caches need to lock mutexes for all Table_cache instances, but they are rare.

This significantly increases scalability in some scenarios.

Definition at line 38 of file table_cache.h.

Member Function Documentation

bool Table_cache::add_used_table	(	THD *	thd,
		TABLE *	table
	)

inline

Add newly created TABLE object which is going to be used right away to the table cache.

Note: Caller should own lock on the table cache.; Sets TABLE::in_use member as side effect.

Return values

false	- success.
true	- failure.

Definition at line 346 of file table_cache.h.

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void Table_cache::assert_owner ( )

inline

Assert that caller owns lock on the table cache.

Definition at line 119 of file table_cache.h.

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uint Table_cache::cached_tables ( ) const

inline

Get number of TABLE instances in the cache.

Definition at line 131 of file table_cache.h.

void Table_cache::destroy ( )

Destroy instance of table cache.

Definition at line 77 of file table_cache.cc.

void Table_cache::free_all_unused_tables ( )

Free all unused TABLE objects in the table cache.

Definition at line 151 of file table_cache.cc.

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TABLE * Table_cache::get_table	(	THD *	thd,
		my_hash_value_type	hash_value,
		const char *	key,
		uint	key_length,
		TABLE_SHARE **	share
	)

inline

Get an unused TABLE instance from the table cache.

Parameters

	thd	Thread context.
	hash_value	Hash value for the key identifying table.
	key	Key identifying table.
	key_length	Length of key for the table.
[out]	share	NULL - if table cache doesn't contain any information about the table (i.e. doesn't have neither used nor unused TABLE objects for it). Pointer to TABLE_SHARE for the table otherwise.

Note: Caller should own lock on the table cache.; Sets TABLE::in_use member as side effect.

Return values

non-NULL	- pointer to unused TABLE object, "share" out-parameter contains pointer to TABLE_SHARE for this table.
NULL	- no unused TABLE object was found, "share" parameter contains pointer to TABLE_SHARE for this table if there are used TABLE objects in cache and NULL otherwise.

Definition at line 461 of file table_cache.h.

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