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One of the reported problems manifested itself in the scenario when one thread tried to to get statistics on a key cache while the second thread had not finished initialization of the key cache structure yet. The problem was resolved by forcing serialization of such operations on key caches. To serialize function calls to perform certain operations over a key cache a new mutex associated with the key cache now is used. It is stored in the field op_lock of the KEY_CACHE structure. It is locked when the operation is performed. Some of the serialized key cache operations utilize calls for other key cache operations. To avoid recursive locking of op_lock the new functions that perform the operations of key cache initialization, destruction and re-partitioning with an additional parameter were introduced. The parameter says whether the operation over op_lock are to be performed or are to be omitted. The old functions for the operations of key cache initialization, destruction,and re-partitioning now just call the corresponding new functions with the additional parameter set to true requesting to use op_lock while all other calls of these new function have this parameter set to false. Another problem reported in the bug entry concerned the operation of assigning an index to a key cache. This operation can be called while the key cache structures are not initialized yet. In this case any call of flush_key_blocks() should return without any actions. No test case is provided with this patch.
209 lines
8.3 KiB
C
209 lines
8.3 KiB
C
/*
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Copyright (c) 2003-2007 MySQL AB, 2009 Sun Microsystems, Inc.
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Use is subject to license terms.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; version 2 of the License.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/* Key cache variable structures */
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#ifndef _keycache_h
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#define _keycache_h
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C_MODE_START
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/*
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Currently the default key cache is created as non-partitioned at
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the start of the server unless the server is started with the parameter
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--key-cache-partitions that is greater than 0
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*/
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#define DEFAULT_KEY_CACHE_PARTITIONS 0
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/*
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MAX_KEY_CACHE_PARTITIONS cannot be greater than
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sizeof(MYISAM_SHARE::dirty_part_map)
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Currently sizeof(MYISAM_SHARE::dirty_part_map)=sizeof(ulonglong)
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*/
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#define MAX_KEY_CACHE_PARTITIONS 64
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/* The structure to get statistical data about a key cache */
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typedef struct st_key_cache_statistics
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{
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ulonglong mem_size; /* memory for cache buffers/auxiliary structures */
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ulonglong block_size; /* size of the each buffers in the key cache */
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ulonglong blocks_used; /* maximum number of used blocks/buffers */
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ulonglong blocks_unused; /* number of currently unused blocks */
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ulonglong blocks_changed; /* number of currently dirty blocks */
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ulonglong blocks_warm; /* number of blocks in warm sub-chain */
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ulonglong read_requests; /* number of read requests (read hits) */
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ulonglong reads; /* number of actual reads from files into buffers */
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ulonglong write_requests; /* number of write requests (write hits) */
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ulonglong writes; /* number of actual writes from buffers into files */
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} KEY_CACHE_STATISTICS;
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#define NUM_LONG_KEY_CACHE_STAT_VARIABLES 3
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/* The type of a key cache object */
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typedef enum key_cache_type
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{
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SIMPLE_KEY_CACHE,
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PARTITIONED_KEY_CACHE
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} KEY_CACHE_TYPE;
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typedef
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int (*INIT_KEY_CACHE)
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(void *, uint key_cache_block_size,
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size_t use_mem, uint division_limit, uint age_threshold);
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typedef
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int (*RESIZE_KEY_CACHE)
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(void *, uint key_cache_block_size,
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size_t use_mem, uint division_limit, uint age_threshold);
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typedef
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void (*CHANGE_KEY_CACHE_PARAM)
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(void *keycache_cb,
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uint division_limit, uint age_threshold);
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typedef
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uchar* (*KEY_CACHE_READ)
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(void *keycache_cb,
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File file, my_off_t filepos, int level,
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uchar *buff, uint length,
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uint block_length, int return_buffer);
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typedef
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int (*KEY_CACHE_INSERT)
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(void *keycache_cb,
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File file, my_off_t filepos, int level,
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uchar *buff, uint length);
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typedef
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int (*KEY_CACHE_WRITE)
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(void *keycache_cb,
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File file, void *file_extra,
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my_off_t filepos, int level,
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uchar *buff, uint length,
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uint block_length, int force_write);
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typedef
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int (*FLUSH_KEY_BLOCKS)
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(void *keycache_cb,
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int file, void *file_extra,
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enum flush_type type);
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typedef
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int (*RESET_KEY_CACHE_COUNTERS)
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(const char *name, void *keycache_cb);
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typedef
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void (*END_KEY_CACHE)
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(void *keycache_cb, my_bool cleanup);
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typedef
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void (*GET_KEY_CACHE_STATISTICS)
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(void *keycache_cb, uint partition_no,
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KEY_CACHE_STATISTICS *key_cache_stats);
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/*
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An object of the type KEY_CACHE_FUNCS contains pointers to all functions
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from the key cache interface.
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Currently a key cache can be of two types: simple and partitioned.
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For each of them its own static structure of the type KEY_CACHE_FUNCS is
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defined . The structures contain the pointers to the implementations of
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the interface functions used by simple key caches and partitioned key
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caches respectively. Pointers to these structures are assigned to key cache
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objects at the time of their creation.
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*/
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typedef struct st_key_cache_funcs
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{
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INIT_KEY_CACHE init;
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RESIZE_KEY_CACHE resize;
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CHANGE_KEY_CACHE_PARAM change_param;
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KEY_CACHE_READ read;
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KEY_CACHE_INSERT insert;
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KEY_CACHE_WRITE write;
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FLUSH_KEY_BLOCKS flush;
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RESET_KEY_CACHE_COUNTERS reset_counters;
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END_KEY_CACHE end;
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GET_KEY_CACHE_STATISTICS get_stats;
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} KEY_CACHE_FUNCS;
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typedef struct st_key_cache
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{
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KEY_CACHE_TYPE key_cache_type; /* type of the key cache used for debugging */
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void *keycache_cb; /* control block of the used key cache */
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KEY_CACHE_FUNCS *interface_funcs; /* interface functions of the key cache */
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ulonglong param_buff_size; /* size the memory allocated for the cache */
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ulong param_block_size; /* size of the blocks in the key cache */
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ulong param_division_limit; /* min. percentage of warm blocks */
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ulong param_age_threshold; /* determines when hot block is downgraded */
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ulong param_partitions; /* number of the key cache partitions */
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my_bool key_cache_inited; /* <=> key cache has been created */
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my_bool can_be_used; /* usage of cache for read/write is allowed */
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my_bool in_init; /* set to 1 in MySQL during init/resize */
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uint partitions; /* actual number of partitions */
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size_t key_cache_mem_size; /* specified size of the cache memory */
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pthread_mutex_t op_lock; /* to serialize operations like 'resize' */
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} KEY_CACHE;
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/* The default key cache */
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extern KEY_CACHE dflt_key_cache_var, *dflt_key_cache;
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extern int init_key_cache(KEY_CACHE *keycache, uint key_cache_block_size,
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size_t use_mem, uint division_limit,
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uint age_threshold, uint partitions);
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extern int resize_key_cache(KEY_CACHE *keycache, uint key_cache_block_size,
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size_t use_mem, uint division_limit,
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uint age_threshold);
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extern void change_key_cache_param(KEY_CACHE *keycache, uint division_limit,
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uint age_threshold);
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extern uchar *key_cache_read(KEY_CACHE *keycache,
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File file, my_off_t filepos, int level,
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uchar *buff, uint length,
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uint block_length,int return_buffer);
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extern int key_cache_insert(KEY_CACHE *keycache,
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File file, my_off_t filepos, int level,
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uchar *buff, uint length);
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extern int key_cache_write(KEY_CACHE *keycache,
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File file, void *file_extra,
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my_off_t filepos, int level,
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uchar *buff, uint length,
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uint block_length, int force_write);
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extern int flush_key_blocks(KEY_CACHE *keycache,
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int file, void *file_extra,
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enum flush_type type);
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extern void end_key_cache(KEY_CACHE *keycache, my_bool cleanup);
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extern void get_key_cache_statistics(KEY_CACHE *keycache,
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uint partition_no,
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KEY_CACHE_STATISTICS *key_cache_stats);
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/* Functions to handle multiple key caches */
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extern my_bool multi_keycache_init(void);
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extern void multi_keycache_free(void);
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extern KEY_CACHE *multi_key_cache_search(uchar *key, uint length,
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KEY_CACHE *def);
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extern my_bool multi_key_cache_set(const uchar *key, uint length,
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KEY_CACHE *key_cache);
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extern void multi_key_cache_change(KEY_CACHE *old_data,
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KEY_CACHE *new_data);
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extern int reset_key_cache_counters(const char *name,
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KEY_CACHE *key_cache);
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extern int repartition_key_cache(KEY_CACHE *keycache,
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uint key_cache_block_size,
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size_t use_mem,
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uint division_limit,
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uint age_threshold,
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uint partitions);
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C_MODE_END
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#endif /* _keycache_h */
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