Many files:

  Improved concurrency for key cache reassignment


include/my_sys.h:
  Improved concurrency for key cache reassignment
include/myisam.h:
  Improved concurrency for key cache reassignment
myisam/mi_keycache.c:
  Improved concurrency for key cache reassignment
myisam/mi_locking.c:
  Improved concurrency for key cache reassignment
mysys/mf_keycache.c:
  Improved concurrency for key cache reassignment
sql/ha_myisam.cc:
  Improved concurrency for key cache reassignment
sql/sql_table.cc:
  Improved concurrency for key cache reassignment

include/my_sys.h

@@ -262,7 +262,8 @@ enum cache_type
 
 enum flush_type
 {
-  FLUSH_KEEP, FLUSH_RELEASE, FLUSH_IGNORE_CHANGED, FLUSH_FORCE_WRITE
+  FLUSH_KEEP, FLUSH_RELEASE, FLUSH_IGNORE_CHANGED, FLUSH_FORCE_WRITE, 
+  FLUSH_REMOVE
 };
 
 typedef struct st_record_cache	/* Used when cacheing records */
@@ -527,6 +528,9 @@ typedef struct st_key_cache_var
   ulong cache_read;              /* number of reads from files to the cache  */
   int blocks;                    /* max number of blocks in the cache        */
   struct st_key_cache_asmt *assign_list; /* list of assignments to the cache */
+  int assignments;               /* number of not completed assignments      */
+  void (*action)(void *);        /* optional call back function              */
+  void *extra_info;              /* ptr to extra info                        */
 } KEY_CACHE_VAR;
 
 #define DEFAULT_KEY_CACHE_NAME "default"

include/myisam.h

@@ -411,7 +411,8 @@ int mi_init_bulk_insert(MI_INFO *info, ulong cache_size, ha_rows rows);
 void mi_flush_bulk_insert(MI_INFO *info, uint inx);
 void mi_end_bulk_insert(MI_INFO *info);
 int mi_assign_to_keycache(MI_INFO *info, ulonglong key_map, 
-                          KEY_CACHE_HANDLE *reg_keycache);
+                          KEY_CACHE_VAR *key_cache, 
+                          pthread_mutex_t *assign_lock);
 int mi_preload(MI_INFO *info, ulonglong key_map, my_bool ignore_leaves);
 
 #ifdef	__cplusplus

myisam/mi_keycache.c

@@ -39,24 +39,68 @@
     of the table will be assigned to the specified key cache.
 */
 
+typedef struct st_assign_extra_info
+{
+  pthread_mutex_t *lock; 
+  struct st_my_thread_var *waiting_thread;
+} ASSIGN_EXTRA_INFO;
+
+static void remove_key_cache_assign(void *arg)
+{
+  KEY_CACHE_VAR *key_cache= (KEY_CACHE_VAR *) arg;
+  ASSIGN_EXTRA_INFO *extra_info= (ASSIGN_EXTRA_INFO *) key_cache->extra_info;
+  struct st_my_thread_var *waiting_thread;
+  pthread_mutex_t *lock= extra_info->lock;
+  pthread_mutex_lock(lock);
+  if (!(--key_cache->assignments) && 
+      (waiting_thread = extra_info->waiting_thread))
+  {
+    my_free(extra_info, MYF(0));
+    key_cache->extra_info= 0;
+    if (waiting_thread != my_thread_var)
+      pthread_cond_signal(&waiting_thread->suspend);
+  }
+  pthread_mutex_unlock(lock);
+}
+
 int mi_assign_to_keycache(MI_INFO *info, ulonglong key_map, 
-                          KEY_CACHE_HANDLE *reg_keycache)
+                          KEY_CACHE_VAR *key_cache, 
+                          pthread_mutex_t *assign_lock)
 {
+  ASSIGN_EXTRA_INFO *extra_info;
   int error= 0;
   MYISAM_SHARE* share= info->s;
 
   DBUG_ENTER("mi_assign_to_keycache");
 
-  share->reg_keycache= reg_keycache;
+  share->reg_keycache= &key_cache->cache;
+  pthread_mutex_lock(assign_lock);
+  if (!(extra_info= (ASSIGN_EXTRA_INFO *) key_cache->extra_info))
+  {
+    if (!(extra_info= (ASSIGN_EXTRA_INFO*) my_malloc(sizeof(ASSIGN_EXTRA_INFO),
+					           MYF(MY_WME | MY_ZEROFILL))))
+      DBUG_RETURN(HA_ERR_OUT_OF_MEM);
+    key_cache->extra_info= extra_info;
+    key_cache->action= remove_key_cache_assign;
+    extra_info->lock= assign_lock;
+  }
+  key_cache->assignments++;
+  pthread_mutex_unlock(assign_lock);
+  
   if (!(info->lock_type == F_WRLCK && share->w_locks))
   {
-    if (flush_key_blocks(*share->keycache, share->kfile, FLUSH_RELEASE))
+    if (flush_key_blocks(*share->keycache, share->kfile, FLUSH_REMOVE))
     {
       error=my_errno;
       mi_mark_crashed(info);		/* Mark that table must be checked */
     }
-    share->keycache= reg_keycache;
+    share->keycache= &key_cache->cache;
   }
+  else
+  {
+    extra_info->waiting_thread= my_thread_var;
+  }
+
     
   DBUG_RETURN(error);
 }

myisam/mi_locking.c

@@ -62,17 +62,12 @@ int mi_lock_database(MI_INFO *info, int lock_type)
       /*
          During a key cache reassignment the current and registered
          key caches for the table are different.
-         Although at present key cache ressignment is always
-         performed with a shared cache for the table acquired,
-         for future possible optimizations we still
-         handle this situation as if we could come to this point 
-         during the ressignment (in non-reassignment thread).
       */ 
       if (info->lock_type == F_WRLCK && !share->w_locks &&
 	  ((switch_fl= share->keycache != share->reg_keycache) ||
            !share->delay_key_write) && 
            flush_key_blocks(*share->keycache, share->kfile,
-                            switch_fl ? FLUSH_RELEASE : FLUSH_KEEP))
+                            switch_fl ? FLUSH_REMOVE : FLUSH_KEEP))
       {
 	error=my_errno;
 	mi_mark_crashed(info);		/* Mark that table must be checked */

mysys/mf_keycache.c

@@ -425,7 +425,7 @@ int init_key_cache(KEY_CACHE_HANDLE *pkeycache, uint key_cache_block_size,
     keycache->min_warm_blocks= env && env->division_limit ?
                                  blocks * env->division_limit / 100 + 1 :
                                  blocks;
-    keycache->age_threshold= env || env->age_threshold ?
+    keycache->age_threshold= env && env->age_threshold ?
                                blocks * env->age_threshold / 100 :
                                blocks;                                         
 
@@ -535,6 +535,7 @@ int resize_key_cache(KEY_CACHE_HANDLE *pkeycache, uint key_cache_block_size,
 void change_key_cache_param(KEY_CACHE_HANDLE keycache)
 {
   KEY_CACHE_VAR *env= keycache->env;
+  DBUG_ENTER("change_key_cache_param");
 
   if (!env)
     return;
@@ -544,6 +545,7 @@ void change_key_cache_param(KEY_CACHE_HANDLE keycache)
   if (env->age_threshold)
     keycache->age_threshold= keycache->disk_blocks *
                                   env->age_threshold / 100;
+  DBUG_VOID_RETURN;
 }
 
 
@@ -1283,7 +1285,7 @@ restart:
       KEYCACHE_DBUG_PRINT("find_key_block",
                           ("request waiting for old page to be saved"));
       {
-        struct st_my_thread_var *thread=my_thread_var;
+        struct st_my_thread_var *thread= my_thread_var;
         /* Put the request into the queue of those waiting for the old page */
         add_to_queue(&block->wqueue[COND_FOR_SAVED], thread);
         /* Wait until the request can be resubmitted */
@@ -2038,6 +2040,7 @@ static int flush_cached_blocks(KEY_CACHE *keycache,
 int flush_key_blocks(KEY_CACHE_HANDLE keycache,
                      File file, enum flush_type type)
 {
+  KEY_CACHE_VAR *env;
   BLOCK_LINK *cache_buff[FLUSH_CACHE],**cache;
   int last_errno= 0;
 
@@ -2213,6 +2216,11 @@ restart:
 
   keycache_pthread_mutex_unlock(&keycache->cache_lock);
 
+  if (type == FLUSH_REMOVE && (env= keycache->env) && (env->action))
+  {
+    (*env->action)((void *) env);
+  }
+
 #ifndef DBUG_OFF
   DBUG_EXECUTE("check_keycache",
                test_key_cache(keycache, "end of flush_key_blocks", 0););

sql/ha_myisam.cc

@@ -761,7 +761,7 @@ int ha_myisam::assign_to_keycache(THD* thd, HA_CHECK_OPT *check_opt)
   reassign_key_cache(key_cache_asmt, new_key_cache);
        
   VOID(pthread_mutex_unlock(&LOCK_assign));
-  error= mi_assign_to_keycache(file, map, &new_key_cache->cache);
+  error= mi_assign_to_keycache(file, map, new_key_cache, &LOCK_assign);
   VOID(pthread_mutex_lock(&LOCK_assign));
 
   if (error && !key_cache_asmt->triggered)

sql/sql_table.cc

@@ -1620,15 +1620,19 @@ int reassign_keycache_tables(THD* thd, KEY_CACHE_VAR* src_cache,
   {
     if (key_cache_asmt->to_reassign)
     {
+      bool refresh;
       VOID(pthread_mutex_unlock(&LOCK_assign));
       bzero((byte *) &table, sizeof(table));
       table.option= dest_name;
-      table.lock_type= TL_READ;
       table.db= key_cache_asmt->db_name;
       table.alias= table.real_name= key_cache_asmt->table_name;
       thd->open_options|= HA_OPEN_TO_ASSIGN;
-      table.table = open_ltable(thd, &table, TL_READ);
+      while (!(table.table=open_table(thd,table.db,
+			              table.real_name,table.alias,
+			              &refresh)) && refresh) ;
       thd->open_options&= ~HA_OPEN_TO_ASSIGN;
+      if (!table.table)
+        DBUG_RETURN(-1);
       table.table->pos_in_table_list= &table;
       key_cache_asmt->triggered= 1;
       rc= table.table->file->assign_to_keycache(thd, 0);
@@ -1642,6 +1646,18 @@ int reassign_keycache_tables(THD* thd, KEY_CACHE_VAR* src_cache,
     else
       key_cache_asmt= key_cache_asmt->next;
   }
+  
+  while (src_cache->assignments)
+  {
+    struct st_my_thread_var *waiting_thread= my_thread_var;
+    pthread_cond_wait(&waiting_thread->suspend, &LOCK_assign);
+  }
+  if (src_cache->extra_info)
+  {
+    my_free((char *) src_cache->extra_info, MYF(0));
+    src_cache->extra_info= 0;
+  }
+
   if (remove_fl && !src_cache->assign_list && src_cache != &dflt_key_cache_var)
   {
     end_key_cache(&src_cache->cache, 1);