diff options
Diffstat (limited to 'myisam/mi_locking.c')
| -rw-r--r-- | myisam/mi_locking.c | 60 |
1 files changed, 45 insertions, 15 deletions
diff --git a/myisam/mi_locking.c b/myisam/mi_locking.c index b13ebfb4cad..66950f62321 100644 --- a/myisam/mi_locking.c +++ b/myisam/mi_locking.c @@ -19,7 +19,7 @@ reads info from a isam-table. Must be first request before doing any furter calls to any isamfunktion. Is used to allow many process use the same isamdatabase. - */ +*/ #include "myisamdef.h" @@ -32,12 +32,17 @@ int mi_lock_database(MI_INFO *info, int lock_type) MYISAM_SHARE *share=info->s; uint flag; DBUG_ENTER("mi_lock_database"); - DBUG_PRINT("info",("lock_type: %d", lock_type)); + DBUG_PRINT("enter",("lock_type: %d old lock %d r_locks: %u w_locks: %u " + "global_changed: %d open_count: %u name: '%s'", + lock_type, info->lock_type, share->r_locks, + share->w_locks, + share->global_changed, share->state.open_count, + share->index_file_name)); if (share->options & HA_OPTION_READ_ONLY_DATA || info->lock_type == lock_type) DBUG_RETURN(0); - if (lock_type == F_EXTRA_LCK) + if (lock_type == F_EXTRA_LCK) /* Used by TMP tables */ { ++share->w_locks; ++share->tot_locks; @@ -51,7 +56,6 @@ int mi_lock_database(MI_INFO *info, int lock_type) { switch (lock_type) { case F_UNLCK: - DBUG_PRINT("info", ("old lock: %d", info->lock_type)); if (info->lock_type == F_RDLCK) count= --share->r_locks; else @@ -81,7 +85,7 @@ int mi_lock_database(MI_INFO *info, int lock_type) share->state.process= share->last_process=share->this_process; share->state.unique= info->last_unique= info->this_unique; share->state.update_count= info->last_loop= ++info->this_loop; - if (mi_state_info_write(share->kfile, &share->state, 1)) + if (mi_state_info_write(share->kfile, &share->state, 1)) error=my_errno; share->changed=0; if (myisam_flush) @@ -119,11 +123,17 @@ int mi_lock_database(MI_INFO *info, int lock_type) break; case F_RDLCK: if (info->lock_type == F_WRLCK) - { /* Change RW to READONLY */ + { + /* + Change RW to READONLY + + mysqld does not turn write locks to read locks, + so we're never here in mysqld. + */ if (share->w_locks == 1) { flag=1; - if (my_lock(share->kfile,lock_type,0L,F_TO_EOF, + if (my_lock(share->kfile,lock_type,0L,F_TO_EOF, MYF(MY_SEEK_NOT_DONE))) { error=my_errno; @@ -346,9 +356,10 @@ int _mi_readinfo(register MI_INFO *info, int lock_type, int check_keybuffer) } /* _mi_readinfo */ - /* Every isam-function that uppdates the isam-database must! end */ - /* with this request */ - /* ARGSUSED */ +/* + Every isam-function that uppdates the isam-database MUST end with this + request +*/ int _mi_writeinfo(register MI_INFO *info, uint operation) { @@ -415,12 +426,31 @@ int _mi_test_if_changed(register MI_INFO *info) } /* _mi_test_if_changed */ -/* Put a mark in the .MYI file that someone is updating the table */ +/* + Put a mark in the .MYI file that someone is updating the table + + + DOCUMENTATION + + state.open_count in the .MYI file is used the following way: + - For the first change of the .MYI file in this process open_count is + incremented by mi_mark_file_change(). (We have a write lock on the file + when this happens) + - In mi_close() it's decremented by _mi_decrement_open_count() if it + was incremented in the same process. + + This mean that if we are the only process using the file, the open_count + tells us if the MYISAM file wasn't properly closed. (This is true if + my_disable_locking is set). +*/ + int _mi_mark_file_changed(MI_INFO *info) { char buff[3]; register MYISAM_SHARE *share=info->s; + DBUG_ENTER("_mi_mark_file_changed"); + if (!(share->state.changed & STATE_CHANGED) || ! share->global_changed) { share->state.changed|=(STATE_CHANGED | STATE_NOT_ANALYZED | @@ -434,12 +464,12 @@ int _mi_mark_file_changed(MI_INFO *info) { mi_int2store(buff,share->state.open_count); buff[2]=1; /* Mark that it's changed */ - return (my_pwrite(share->kfile,buff,sizeof(buff), - sizeof(share->state.header), - MYF(MY_NABP))); + DBUG_RETURN(my_pwrite(share->kfile,buff,sizeof(buff), + sizeof(share->state.header), + MYF(MY_NABP))); } } - return 0; + DBUG_RETURN(0); } |