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- Committer: Brian Aker
- Date: 2009-07-27 04:14:30 UTC
- mfrom: (1093.6.2 table_share)
- Revision ID: brian@gaz-20090727041430-kmxsnb2ep1cqsy05
Merge
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drizzled/table_share.cc
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/* -*- mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; -*-
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* vim:expandtab:shiftwidth=2:tabstop=2:smarttab:
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*
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* Copyright (C) 2009 Sun Microsystems
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*
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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; either version 2 of the License, or
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* (at your option) any later version.
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*
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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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*
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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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/*
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This class is shared between different table objects. There is one
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instance of table share per one table in the database.
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*/
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/* Basic functions needed by many modules */
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#include <drizzled/server_includes.h>
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#include <assert.h>
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#include <drizzled/error.h>
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#include <drizzled/gettext.h>
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#include <drizzled/sql_base.h>
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using namespace std;
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static HASH table_def_cache;
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static pthread_mutex_t LOCK_table_share;
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bool table_def_inited= false;
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/*****************************************************************************
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Functions to handle table definition cach (TableShare)
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*****************************************************************************/
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extern "C"
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{
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unsigned char *table_def_key(const unsigned char *record,
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size_t *length,
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bool );
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}
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unsigned char *table_def_key(const unsigned char *record,
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size_t *length,
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bool )
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{
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TableShare *entry=(TableShare*) record;
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*length= entry->table_cache_key.length;
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return (unsigned char*) entry->table_cache_key.str;
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}
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static void table_def_free_entry(TableShare *share)
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{
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share->free_table_share();
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}
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bool TableShare::cacheStart(void)
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{
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table_def_inited= true;
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pthread_mutex_init(&LOCK_table_share, MY_MUTEX_INIT_FAST);
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return hash_init(&table_def_cache, &my_charset_bin, (size_t)table_def_size,
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0, 0, table_def_key,
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(hash_free_key) table_def_free_entry, 0);
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}
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void TableShare::cacheStop(void)
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{
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if (table_def_inited)
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{
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table_def_inited= 0;
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pthread_mutex_destroy(&LOCK_table_share);
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hash_free(&table_def_cache);
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}
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}
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uint32_t cached_table_definitions(void)
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{
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return table_def_cache.records;
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}
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/*
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Mark that we are not using table share anymore.
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SYNOPSIS
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release()
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share Table share
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IMPLEMENTATION
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If ref_count goes to zero and (we have done a refresh or if we have
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already too many open table shares) then delete the definition.
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*/
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void TableShare::release(TableShare *share)
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{
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bool to_be_deleted= false;
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safe_mutex_assert_owner(&LOCK_open);
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pthread_mutex_lock(&share->mutex);
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if (!--share->ref_count)
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to_be_deleted= true;
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if (to_be_deleted)
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{
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hash_delete(&table_def_cache, (unsigned char*) share);
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return;
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}
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pthread_mutex_unlock(&share->mutex);
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}
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void TableShare::release(const char *key, uint32_t key_length)
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{
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TableShare *share;
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if ((share= (TableShare*) hash_search(&table_def_cache,(unsigned char*) key,
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key_length)))
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{
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share->version= 0; // Mark for delete
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if (share->ref_count == 0)
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{
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pthread_mutex_lock(&share->mutex);
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hash_delete(&table_def_cache, (unsigned char*) share);
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}
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}
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}
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/*
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Get TableShare for a table.
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get_table_share()
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session Thread handle
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table_list Table that should be opened
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key Table cache key
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key_length Length of key
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error out: Error code from open_table_def()
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IMPLEMENTATION
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Get a table definition from the table definition cache.
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If it doesn't exist, create a new from the table definition file.
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NOTES
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We must have wrlock on LOCK_open when we come here
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(To be changed later)
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RETURN
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0 Error
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# Share for table
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*/
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TableShare *TableShare::getShare(Session *session,
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TableList *table_list, char *key,
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uint32_t key_length, uint32_t, int *error)
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{
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TableShare *share;
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*error= 0;
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/* Read table definition from cache */
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if ((share= (TableShare*) hash_search(&table_def_cache,(unsigned char*) key,
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key_length)))
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goto found;
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if (!(share= alloc_table_share(table_list, key, key_length)))
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{
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return NULL;
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}
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/*
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Lock mutex to be able to read table definition from file without
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conflicts
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*/
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(void) pthread_mutex_lock(&share->mutex);
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if (my_hash_insert(&table_def_cache, (unsigned char*) share))
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{
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share->free_table_share();
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return NULL; // return error
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}
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if (open_table_def(session, share))
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{
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*error= share->error;
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(void) hash_delete(&table_def_cache, (unsigned char*) share);
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return NULL;
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}
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share->ref_count++; // Mark in use
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(void) pthread_mutex_unlock(&share->mutex);
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return(share);
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found:
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/*
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We found an existing table definition. Return it if we didn't get
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an error when reading the table definition from file.
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*/
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/* We must do a lock to ensure that the structure is initialized */
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(void) pthread_mutex_lock(&share->mutex);
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if (share->error)
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{
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/* Table definition contained an error */
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share->open_table_error(share->error, share->open_errno, share->errarg);
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(void) pthread_mutex_unlock(&share->mutex);
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return NULL;
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}
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share->ref_count++;
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(void) pthread_mutex_unlock(&share->mutex);
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return share;
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}
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/*
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Check if table definition exits in cache
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SYNOPSIS
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get_cached_table_share()
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db Database name
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table_name Table name
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RETURN
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0 Not cached
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# TableShare for table
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*/
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TableShare *TableShare::getShare(const char *db, const char *table_name)
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{
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char key[NAME_LEN*2+2];
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uint32_t key_length;
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safe_mutex_assert_owner(&LOCK_open);
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key_length= TableShare::createKey(key, db, table_name);
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return (TableShare*) hash_search(&table_def_cache,(unsigned char*) key, key_length);
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}
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