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Diffstat (limited to 'myisam/mi_keycache.c')
| -rw-r--r-- | myisam/mi_keycache.c | 161 |
1 files changed, 161 insertions, 0 deletions
diff --git a/myisam/mi_keycache.c b/myisam/mi_keycache.c new file mode 100644 index 00000000000..99a2fd6db15 --- /dev/null +++ b/myisam/mi_keycache.c @@ -0,0 +1,161 @@ +/* Copyright (C) 2003 MySQL AB + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 2 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program; if not, write to the Free Software + Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ + +/* + Key cache assignments +*/ + +#include "myisamdef.h" + +/* + Assign pages of the index file for a table to a key cache + + SYNOPSIS + mi_assign_to_key_cache() + info open table + key_map map of indexes to assign to the key cache + key_cache_ptr pointer to the key cache handle + assign_lock Mutex to lock during assignment + + PREREQUESTS + One must have a READ lock or a WRITE lock on the table when calling + the function to ensure that there is no other writers to it. + + The caller must also ensure that one doesn't call this function from + two different threads with the same table. + + NOTES + At present pages for all indexes must be assigned to the same key cache. + In future only pages for indexes specified in the key_map parameter + of the table will be assigned to the specified key cache. + + RETURN VALUE + 0 If a success + # Error code +*/ + +int mi_assign_to_key_cache(MI_INFO *info, + ulonglong key_map __attribute__((unused)), + KEY_CACHE *key_cache) +{ + int error= 0; + MYISAM_SHARE* share= info->s; + DBUG_ENTER("mi_assign_to_key_cache"); + DBUG_PRINT("enter",("old_key_cache_handle: %lx new_key_cache_handle: %lx", + share->key_cache, key_cache)); + + /* + Skip operation if we didn't change key cache. This can happen if we + call this for all open instances of the same table + */ + if (share->key_cache == key_cache) + DBUG_RETURN(0); + + /* + First flush all blocks for the table in the old key cache. + This is to ensure that the disk is consistent with the data pages + in memory (which may not be the case if the table uses delayed_key_write) + + Note that some other read thread may still fill in the key cache with + new blocks during this call and after, but this doesn't matter as + all threads will start using the new key cache for their next call to + myisam library and we know that there will not be any changed blocks + in the old key cache. + */ + + if (flush_key_blocks(share->key_cache, share->kfile, FLUSH_RELEASE)) + { + error= my_errno; + mi_mark_crashed(info); /* Mark that table must be checked */ + } + + /* + Flush the new key cache for this file. This is needed to ensure + that there is no old blocks (with outdated data) left in the new key + cache from an earlier assign_to_keycache operation + + (This can never fail as there is never any not written data in the + new key cache) + */ + (void) flush_key_blocks(key_cache, share->kfile, FLUSH_RELEASE); + + /* + ensure that setting the key cache and changing the multi_key_cache + is done atomicly + */ + pthread_mutex_lock(&share->intern_lock); + /* + Tell all threads to use the new key cache + This should be seen at the lastes for the next call to an myisam function. + */ + share->key_cache= key_cache; + + /* store the key cache in the global hash structure for future opens */ + if (multi_key_cache_set(share->unique_file_name, share->unique_name_length, + share->key_cache)) + error= my_errno; + pthread_mutex_unlock(&share->intern_lock); + DBUG_RETURN(error); +} + + +/* + Change all MyISAM entries that uses one key cache to another key cache + + SYNOPSIS + mi_change_key_cache() + old_key_cache Old key cache + new_key_cache New key cache + + NOTES + This is used when we delete one key cache. + + To handle the case where some other threads tries to open an MyISAM + table associated with the to-be-deleted key cache while this operation + is running, we have to call 'multi_key_cache_change()' from this + function while we have a lock on the MyISAM table list structure. + + This is safe as long as it's only MyISAM that is using this specific + key cache. +*/ + + +void mi_change_key_cache(KEY_CACHE *old_key_cache, + KEY_CACHE *new_key_cache) +{ + LIST *pos; + DBUG_ENTER("mi_change_key_cache"); + + /* + Lock list to ensure that no one can close the table while we manipulate it + */ + pthread_mutex_lock(&THR_LOCK_myisam); + for (pos=myisam_open_list ; pos ; pos=pos->next) + { + MI_INFO *info= (MI_INFO*) pos->data; + MYISAM_SHARE *share= info->s; + if (share->key_cache == old_key_cache) + mi_assign_to_key_cache(info, (ulonglong) ~0, new_key_cache); + } + + /* + We have to do the following call while we have the lock on the + MyISAM list structure to ensure that another thread is not trying to + open a new table that will be associted with the old key cache + */ + multi_key_cache_change(old_key_cache, new_key_cache); + pthread_mutex_unlock(&THR_LOCK_myisam); +} |