WL#2935 - SHOW STATUS support in plugins

The patch adds DYNAMIC_ARRAY all_status_vars, which is now the
sole source of status information for SHOW STATUS.  Status
variables can be added to and removed from the array dynamically.
SHOW STATUS command uses this array instead of static array
from mysqld.cc
Compatibility with the old, global list of status variables is
preserved in init_server_components(), where this global list is
simply appended to all_status_vars.


include/plugin.h:
  WL#2935 - SHOW STATUS support in plugins
plugin/fulltext/plugin_example.c:
  WL#2935 - SHOW STATUS support in plugins
  example
sql/ha_innodb.cc:
  s/struct show_var_st/SHOW_VAR/
sql/ha_innodb.h:
  s/struct show_var_st/SHOW_VAR/
sql/mysql_priv.h:
  WL#2935 - SHOW STATUS support in plugins
  add_status_vars(), remove_status_vars()
sql/mysqld.cc:
  bug: plugin_free must be called even with --skip-grants
  add_status_vars()/free_status_vars(), remove unused SHOW_xxx_CONST
  s/struct show_var_st/SHOW_VAR/
sql/set_var.cc:
  s/struct show_var_st/SHOW_VAR/
sql/sql_parse.cc:
  s/struct show_var_st/SHOW_VAR/
sql/sql_plugin.cc:
  WL#2935 - SHOW STATUS support in plugins
sql/sql_plugin.h:
  WL#2935 - SHOW STATUS support in plugins
sql/sql_show.cc:
  WL#2935 - SHOW STATUS support in plugins
  DYNAMIC_ARRAY all_status_vars, add_status_vars(), remove_status_vars()
  s/struct show_var_st/SHOW_VAR/
sql/structs.h:
  WL#2935 - SHOW STATUS support in plugins
  SHOW STATUS definitions moved to include/plugin.h and sql_plugin.h
  s/struct show_var_st/SHOW_VAR/

include/plugin.h

@@ -41,7 +41,26 @@
 int _mysql_plugin_interface_version_= MYSQL_PLUGIN_INTERFACE_VERSION; \
 int _mysql_sizeof_struct_st_plugin_= sizeof(struct st_mysql_plugin); \
 struct st_mysql_plugin _mysql_plugin_declarations_[]= {
-#define mysql_declare_plugin_end ,{0,0,0,0,0,0,0}}
+#define mysql_declare_plugin_end ,{0,0,0,0,0,0,0,0}}
+
+/*
+  declarations for SHOW STATUS support in plugins
+*/
+enum enum_mysql_show_type
+{
+  SHOW_UNDEF, SHOW_BOOL, SHOW_MY_BOOL, SHOW_INT, SHOW_LONG,
+  SHOW_LONGLONG, SHOW_CHAR, SHOW_CHAR_PTR,
+  SHOW_ARRAY, SHOW_FUNC
+};
+
+struct st_mysql_show_var {
+  const char *name;
+  char *value;
+  enum enum_mysql_show_type type;
+};
+
+#define SHOW_VAR_FUNC_BUFF_SIZE 1024
+typedef int (*mysql_show_var_func)(void *, struct st_mysql_show_var*, char *);
 
 /*
   Plugin description structure.
@@ -57,6 +76,7 @@ struct st_mysql_plugin
   int (*init)(void);    /* the function to invoke when plugin is loaded */
   int (*deinit)(void);  /* the function to invoke when plugin is unloaded */
   uint version;         /* plugin version (for SHOW PLUGINS)            */
+  struct st_mysql_show_var *status_vars;
 };
 
 /*************************************************************************

plugin/fulltext/plugin_example.c

@@ -18,6 +18,8 @@
 #include <m_ctype.h>
 #include <plugin.h>
 
+long number_of_calls= 0; /* for SHOW STATUS, see below */
+
 /*
   Simple full-text parser plugin that acts as a replacement for the
   built-in full-text parser:
@@ -167,6 +169,8 @@ int simple_parser_parse(MYSQL_FTPARSER_PARAM *param)
 {
   char *end, *start, *docend= param->doc + param->length;
 
+  number_of_calls++;
+
   for (end= start= param->doc;; end++)
   {
     if (end == docend)
@@ -198,6 +202,16 @@ static struct st_mysql_ftparser simple_parser_descriptor=
   simple_parser_deinit              /* parser deinit function */
 };
 
+/*
+  Plugin status variables for SHOW STATUS
+*/
+
+struct st_mysql_show_var simple_status[]=
+{
+  {"static",     "just a static text",     SHOW_CHAR},
+  {"called",     (char *)&number_of_calls, SHOW_LONG},
+  {0,0,0}
+};
 
 /*
   Plugin library descriptor
@@ -211,6 +225,8 @@ mysql_declare_plugin
   "MySQL AB",                 /* author                          */
   "Simple Full-Text Parser",  /* description                     */
   simple_parser_plugin_init,  /* init function (when loaded)     */
-  simple_parser_plugin_deinit /* deinit function (when unloaded) */
+  simple_parser_plugin_deinit,/* deinit function (when unloaded) */
+  0x0001,                     /* version                         */
+  &simple_status              /* status variables                */
 }
 mysql_declare_plugin_end;

sql/ha_innodb.cc

@@ -253,7 +253,7 @@ innobase_commit_low(
 /*================*/
 	trx_t*	trx);	/* in: transaction handle */
 
-struct show_var_st innodb_status_variables[]= {
+SHOW_VAR innodb_status_variables[]= {
   {"buffer_pool_pages_data",
   (char*) &export_vars.innodb_buffer_pool_pages_data,     SHOW_LONG},
   {"buffer_pool_pages_dirty",

sql/ha_innodb.h

@@ -212,7 +212,7 @@ class ha_innobase: public handler
 					uint table_changes);
 };
 
-extern struct show_var_st innodb_status_variables[];
+extern SHOW_VAR innodb_status_variables[];
 extern uint innobase_init_flags, innobase_lock_type;
 extern uint innobase_flush_log_at_trx_commit;
 extern ulong innobase_cache_size, innobase_fast_shutdown;

sql/mysql_priv.h

@@ -292,7 +292,7 @@ extern CHARSET_INFO *national_charset_info, *table_alias_charset;
 #define OPTION_SETUP_TABLES_DONE        (LL(1) << 30) // intern
 /* If not set then the thread will ignore all warnings with level notes. */
 #define OPTION_SQL_NOTES                (LL(1) << 31) // THD, user
-/* 
+/*
   Force the used temporary table to be a MyISAM table (because we will use
   fulltext functions when reading from it.
 */
@@ -322,7 +322,7 @@ extern CHARSET_INFO *national_charset_info, *table_alias_charset;
 #define MODE_DB2			2048
 #define MODE_MAXDB			4096
 #define MODE_NO_KEY_OPTIONS             8192
-#define MODE_NO_TABLE_OPTIONS           16384 
+#define MODE_NO_TABLE_OPTIONS           16384
 #define MODE_NO_FIELD_OPTIONS           32768
 #define MODE_MYSQL323                   65536
 #define MODE_MYSQL40                    (MODE_MYSQL323*2)
@@ -513,13 +513,11 @@ void free_items(Item *item);
 void cleanup_items(Item *item);
 class THD;
 void close_thread_tables(THD *thd, bool locked=0, bool skip_derived=0);
-bool check_one_table_access(THD *thd, ulong privilege,
-			   TABLE_LIST *tables);
+bool check_one_table_access(THD *thd, ulong privilege, TABLE_LIST *tables);
 bool check_routine_access(THD *thd,ulong want_access,char *db,char *name,
 			  bool is_proc, bool no_errors);
 bool check_some_access(THD *thd, ulong want_access, TABLE_LIST *table);
-bool check_merge_table_access(THD *thd, char *db,
-			      TABLE_LIST *table_list);
+bool check_merge_table_access(THD *thd, char *db, TABLE_LIST *table_list);
 bool check_some_routine_access(THD *thd, const char *db, const char *name, bool is_proc);
 bool multi_update_precheck(THD *thd, TABLE_LIST *tables);
 bool multi_delete_precheck(THD *thd, TABLE_LIST *tables);
@@ -884,6 +882,10 @@ void calc_sum_of_all_status(STATUS_VAR *to);
 void append_definer(THD *thd, String *buffer, const LEX_STRING *definer_user,
                     const LEX_STRING *definer_host);
 
+int add_status_vars(SHOW_VAR *list);
+void remove_status_vars(SHOW_VAR *list);
+void init_status_vars();
+void free_status_vars();
 
 /* information schema */
 extern LEX_STRING information_schema_name;
@@ -1269,7 +1271,7 @@ extern I_List<NAMED_LIST> key_caches;
 extern MY_BITMAP temp_pool;
 extern String my_empty_string;
 extern const String my_null_string;
-extern SHOW_VAR init_vars[],status_vars[], internal_vars[];
+extern SHOW_VAR init_vars[], status_vars[], internal_vars[];
 extern struct system_variables global_system_variables;
 extern struct system_variables max_system_variables;
 extern struct system_status_var global_status_var;

sql/set_var.cc

@@ -624,7 +624,7 @@ sys_var_have_variable sys_have_row_based_replication("have_row_based_replication
 sys_var_const_str		sys_license("license", STRINGIFY_ARG(LICENSE));
 
 #ifdef HAVE_REPLICATION
-static int show_slave_skip_errors(THD *thd, show_var_st *var, char *buff)
+static int show_slave_skip_errors(THD *thd, SHOW_VAR *var, char *buff)
 {
   var->type=SHOW_CHAR;
   var->value= buff;
@@ -667,7 +667,7 @@ static int show_slave_skip_errors(THD *thd, show_var_st *var, char *buff)
   Variables shown by SHOW variables in alphabetical order
 */
 
-struct show_var_st init_vars[]= {
+SHOW_VAR init_vars[]= {
   {"auto_increment_increment", (char*) &sys_auto_increment_increment, SHOW_SYS},
   {"auto_increment_offset",   (char*) &sys_auto_increment_offset, SHOW_SYS},
   {sys_automatic_sp_privileges.name,(char*) &sys_automatic_sp_privileges,       SHOW_SYS},

sql/sql_parse.cc

@@ -6641,7 +6641,7 @@ void kill_one_thread(THD *thd, ulong id, bool only_kill_query)
 static void refresh_status(void)
 {
   pthread_mutex_lock(&LOCK_status);
-  for (struct show_var_st *ptr=status_vars; ptr->name; ptr++)
+  for (SHOW_VAR *ptr= status_vars; ptr->name; ptr++)
     if (ptr->type == SHOW_LONG) // note that SHOW_LONG_NOFLUSH variables are not reset
       *(ulong*) ptr->value= 0;
 

sql/sql_plugin.cc

@@ -94,7 +94,8 @@ static st_plugin_dl *plugin_dl_insert_or_reuse(struct st_plugin_dl *plugin_dl)
 
 static inline void free_plugin_mem(struct st_plugin_dl *p)
 {
-  dlclose(p->handle);
+  if (p->handle)
+    dlclose(p->handle);
   my_free(p->dl.str, MYF(MY_ALLOW_ZERO_PTR));
   if (p->version != MYSQL_PLUGIN_INTERFACE_VERSION)
     my_free((gptr)p->plugins, MYF(MY_ALLOW_ZERO_PTR));
@@ -182,7 +183,7 @@ static st_plugin_dl *plugin_dl_add(LEX_STRING *dl, int report)
   {
     int i, sizeof_st_plugin;
     struct st_mysql_plugin *old, *cur;
-    char *ptr=(char *)sym;
+    char *ptr= (char *)sym;
 
     if ((sym= dlsym(plugin_dl.handle, sizeof_st_plugin_sym)))
       sizeof_st_plugin= *(int *)sym;
@@ -196,8 +197,12 @@ static st_plugin_dl *plugin_dl_add(LEX_STRING *dl, int report)
         sql_print_error(ER(ER_CANT_FIND_DL_ENTRY), sizeof_st_plugin_sym);
       DBUG_RETURN(0);
 #else
+      /*
+        When the following assert starts failing, we'll have to switch
+        to the upper branch of the #ifdef
+      */
       DBUG_ASSERT(min_plugin_interface_version == 0);
-      sizeof_st_plugin=(int)offsetof(struct st_mysql_plugin, version);
+      sizeof_st_plugin= (int)offsetof(struct st_mysql_plugin, version);
 #endif
     }
 
@@ -217,29 +222,17 @@ static st_plugin_dl *plugin_dl_add(LEX_STRING *dl, int report)
         sql_print_error(ER(ER_OUTOFMEMORY), plugin_dl.dl.length);
       DBUG_RETURN(0);
     }
+    /*
+      All st_plugin fields not initialized in the plugin explicitly, are
+      set to 0. It matches C standard behaviour for struct initializers that
+      have less values than the struct definition.
+    */
     for (i=0;
          (old=(struct st_mysql_plugin *)(ptr+i*sizeof_st_plugin))->info;
          i++)
-    {
-      switch (plugin_dl.version) {
-      default: /* version > MYSQL_PLUGIN_INTERFACE_VERSION */
-        /* fall through */
-      case 0x0001:
-        cur[i].version=old->version;
-        // cur[i].status_vars=old->status_vars;
-        /* fall through */
-      case 0x0000:
-        cur[i].type=old->type;
-        cur[i].info=old->info;
-        cur[i].name=old->name;
-        cur[i].author=old->author;
-        cur[i].descr=old->descr;
-        cur[i].init=old->init;
-        cur[i].deinit=old->deinit;
-      }
-    }
+      memcpy(cur+i, old, min(sizeof(cur[i]), sizeof_st_plugin));
 
-    sym=cur;
+    sym= cur;
   }
   plugin_dl.plugins= (struct st_mysql_plugin *)sym;
 
@@ -320,7 +313,7 @@ static struct st_plugin_int *plugin_find_internal(LEX_STRING *name, int type)
     {
       struct st_plugin_int *plugin= (st_plugin_int *)
         hash_search(&plugin_hash[i], (const byte *)name->str, name->length);
-      if (plugin) 
+      if (plugin)
         DBUG_RETURN(plugin);
     }
   }
@@ -382,7 +375,6 @@ static st_plugin_int *plugin_insert_or_reuse(struct st_plugin_int *plugin)
                               struct st_plugin_int *));
 }
 
-
 static my_bool plugin_add(LEX_STRING *name, LEX_STRING *dl, int report)
 {
   struct st_plugin_int tmp;
@@ -429,21 +421,20 @@ static my_bool plugin_add(LEX_STRING *name, LEX_STRING *dl, int report)
       tmp.name.length= name_len;
       tmp.ref_count= 0;
       tmp.state= PLUGIN_IS_UNINITIALIZED;
-      if (! (tmp_plugin_ptr= plugin_insert_or_reuse(&tmp)))
+      if (plugin->status_vars)
       {
-        if (report & REPORT_TO_USER)
-          my_error(ER_OUTOFMEMORY, MYF(0), sizeof(struct st_plugin_int));
-        if (report & REPORT_TO_LOG)
-          sql_print_error(ER(ER_OUTOFMEMORY), sizeof(struct st_plugin_int));
-        goto err;
+        SHOW_VAR array[2]= {
+          {plugin->name, (char*)plugin->status_vars, SHOW_ARRAY},
+          {0, 0, SHOW_UNDEF}
+        };
+        if (add_status_vars(array)) // add_status_vars makes a copy
+          goto err;
       }
+      if (! (tmp_plugin_ptr= plugin_insert_or_reuse(&tmp)))
+        goto err;
       if (my_hash_insert(&plugin_hash[plugin->type], (byte*)tmp_plugin_ptr))
       {
         tmp_plugin_ptr->state= PLUGIN_IS_FREED;
-        if (report & REPORT_TO_USER)
-          my_error(ER_OUTOFMEMORY, MYF(0), sizeof(struct st_plugin_int));
-        if (report & REPORT_TO_LOG)
-          sql_print_error(ER(ER_OUTOFMEMORY), sizeof(struct st_plugin_int));
         goto err;
       }
       DBUG_RETURN(FALSE);
@@ -454,6 +445,14 @@ static my_bool plugin_add(LEX_STRING *name, LEX_STRING *dl, int report)
   if (report & REPORT_TO_LOG)
     sql_print_error(ER(ER_CANT_FIND_DL_ENTRY), name->str);
 err:
+  if (plugin->status_vars)
+  {
+    SHOW_VAR array[2]= {
+      {plugin->name, (char*)plugin->status_vars, SHOW_ARRAY},
+      {0, 0, SHOW_UNDEF}
+    };
+    remove_status_vars(array);
+  }
   plugin_dl_del(dl);
   DBUG_RETURN(TRUE);
 }
@@ -466,6 +465,14 @@ static void plugin_del(LEX_STRING *name)
   DBUG_ENTER("plugin_del");
   if ((plugin= plugin_find_internal(name, MYSQL_ANY_PLUGIN)))
   {
+    if (plugin->plugin->status_vars)
+    {
+      SHOW_VAR array[2]= {
+        {plugin->plugin->name, (char*)plugin->plugin->status_vars, SHOW_ARRAY},
+        {0, 0, SHOW_UNDEF}
+      };
+      remove_status_vars(array);
+    }
     hash_delete(&plugin_hash[plugin->plugin->type], (byte*)plugin);
     plugin_dl_del(&plugin->plugin_dl->dl);
     plugin->state= PLUGIN_IS_FREED;
@@ -494,7 +501,7 @@ void plugin_unlock(struct st_plugin_int *plugin)
 static int plugin_initialize(struct st_plugin_int *plugin)
 {
   DBUG_ENTER("plugin_initialize");
-  
+
   if (plugin->plugin->init)
   {
     if (plugin->plugin->init())
@@ -506,7 +513,7 @@ static int plugin_initialize(struct st_plugin_int *plugin)
       goto err;
     }
   }
-  
+
   switch (plugin->plugin->type)
   {
   case MYSQL_STORAGE_ENGINE_PLUGIN:
@@ -605,11 +612,11 @@ int plugin_init(void)
                   get_hash_key, NULL, 0))
       goto err;
   }
-  
+
   initialized= 1;
 
   DBUG_RETURN(0);
-  
+
 err:
   DBUG_RETURN(1);
 }
@@ -651,9 +658,9 @@ void plugin_load(void)
   MEM_ROOT mem;
   THD *new_thd;
   DBUG_ENTER("plugin_load");
-  
+
   DBUG_ASSERT(initialized);
-  
+
   if (!(new_thd= new THD))
   {
     sql_print_error("Can't allocate memory for plugin structures");
@@ -716,12 +723,7 @@ void plugin_free(void)
   {
     struct st_plugin_dl *tmp= dynamic_element(&plugin_dl_array, i,
                                               struct st_plugin_dl *);
-#ifdef HAVE_DLOPEN
-    if (tmp->handle)
-    {
-      free_plugin_mem(tmp);
-    }
-#endif
+    free_plugin_mem(tmp);
   }
   delete_dynamic(&plugin_dl_array);
   if (initialized)
@@ -746,7 +748,7 @@ my_bool mysql_install_plugin(THD *thd, LEX_STRING *name, LEX_STRING *dl)
   tables.table_name= tables.alias= (char *)"plugin";
   if (check_table_access(thd, INSERT_ACL, &tables, 0))
     DBUG_RETURN(TRUE);
-    
+
   /* need to open before acquiring THR_LOCK_plugin or it will deadlock */
   if (! (table = open_ltable(thd, &tables, TL_WRITE)))
     DBUG_RETURN(TRUE);
@@ -755,7 +757,7 @@ my_bool mysql_install_plugin(THD *thd, LEX_STRING *name, LEX_STRING *dl)
   if (plugin_add(name, dl, REPORT_TO_USER))
     goto err;
   tmp= plugin_find_internal(name, MYSQL_ANY_PLUGIN);
-  
+
   if (plugin_initialize(tmp))
   {
     my_error(ER_CANT_INITIALIZE_UDF, MYF(0), name->str,
@@ -774,7 +776,7 @@ my_bool mysql_install_plugin(THD *thd, LEX_STRING *name, LEX_STRING *dl)
     table->file->print_error(error, MYF(0));
     goto deinit;
   }
-  
+
   rw_unlock(&THR_LOCK_plugin);
   DBUG_RETURN(FALSE);
 deinit:
@@ -815,7 +817,7 @@ my_bool mysql_uninstall_plugin(THD *thd, LEX_STRING *name)
     my_error(ER_SP_DOES_NOT_EXIST, MYF(0), "PLUGIN", name->str);
     goto err;
   }
-  
+
   if (plugin->ref_count)
   {
     plugin->state= PLUGIN_IS_DELETED;
@@ -858,13 +860,13 @@ my_bool plugin_foreach(THD *thd, plugin_foreach_func *func,
   struct st_plugin_int *plugin;
   DBUG_ENTER("mysql_uninstall_plugin");
   rw_rdlock(&THR_LOCK_plugin);
-  
+
   if (type == MYSQL_ANY_PLUGIN)
   {
     for (idx= 0; idx < plugin_array.elements; idx++)
     {
       plugin= dynamic_element(&plugin_array, idx, struct st_plugin_int *);
-      
+
       /* FREED records may have garbage pointers */
       if ((plugin->state != PLUGIN_IS_FREED) &&
           func(thd, plugin, arg))

sql/sql_plugin.h

@@ -17,7 +17,17 @@
 #ifndef _sql_plugin_h
 #define _sql_plugin_h
 
+/*
+  the following #define adds server-only members to enum_mysql_show_type,
+  that is defined in plugin.h
+*/
+#define SHOW_FUNC    SHOW_FUNC, SHOW_KEY_CACHE_LONG, SHOW_KEY_CACHE_LONGLONG, \
+                     SHOW_LONG_STATUS, SHOW_DOUBLE_STATUS, SHOW_HAVE,   \
+                     SHOW_HA_ROWS, SHOW_SYS, SHOW_LONG_NOFLUSH
 #include <plugin.h>
+#undef SHOW_FUNC
+typedef enum enum_mysql_show_type SHOW_TYPE;
+typedef struct st_mysql_show_var SHOW_VAR;
 
 #define MYSQL_ANY_PLUGIN         -1
 
@@ -65,7 +75,7 @@ extern my_bool mysql_uninstall_plugin(THD *thd, LEX_STRING *name);
 
 extern my_bool plugin_register_builtin(struct st_mysql_plugin *plugin);
 
-typedef my_bool (plugin_foreach_func)(THD *thd, 
+typedef my_bool (plugin_foreach_func)(THD *thd,
                                       st_plugin_int *plugin,
                                       void *arg);
 extern my_bool plugin_foreach(THD *thd, plugin_foreach_func *func,

sql/sql_show.cc

@@ -1516,8 +1516,163 @@ void mysqld_list_processes(THD *thd,const char *user, bool verbose)
   Status functions
 *****************************************************************************/
 
+static DYNAMIC_ARRAY all_status_vars;
+static bool status_vars_inited= 0;
+static int show_var_cmp(const void *var1, const void *var2)
+{
+  return strcmp(((SHOW_VAR*)var1)->name, ((SHOW_VAR*)var2)->name);
+}
+
+/*
+  deletes all the SHOW_UNDEF elements from the array and calls
+  delete_dynamic() if it's completely empty.
+*/
+static void shrink_var_array(DYNAMIC_ARRAY *array)
+{
+  int a,b;
+  SHOW_VAR *all= dynamic_element(array, 0, SHOW_VAR *);
+
+  for (a= b= 0; b < array->elements; b++)
+    if (all[b].type != SHOW_UNDEF)
+      all[a++]= all[b];
+  if (a)
+  {
+    bzero(all+a, sizeof(SHOW_VAR)); // writing NULL-element to the end
+    array->elements= a;
+  }
+  else // array is completely empty - delete it
+    delete_dynamic(array);
+}
+
+/*
+  Adds an array of SHOW_VAR entries to the output of SHOW STATUS
+
+  SYNOPSIS
+    add_status_vars(SHOW_VAR *list)
+    list - an array of SHOW_VAR entries to add to all_status_vars
+           the last entry must be {0,0,SHOW_UNDEF}
+
+  NOTE
+    The handling of all_status_vars[] is completely internal, it's allocated
+    automatically when something is added to it, and deleted completely when
+    the last entry is removed.
+
+    As a special optimization, if add_status_vars() is called before
+    init_status_vars(), it assumes "startup mode" - neither concurrent access
+    to the array nor SHOW STATUS are possible (thus it skips locks and qsort)
+
+    The last entry of the all_status_vars[] should always be {0,0,SHOW_UNDEF}
+*/
+int add_status_vars(SHOW_VAR *list)
+{
+  int res= 0;
+  if (status_vars_inited)
+    pthread_mutex_lock(&LOCK_status);
+  if (!all_status_vars.buffer && // array is not allocated yet - do it now
+      my_init_dynamic_array(&all_status_vars, sizeof(SHOW_VAR), 200, 20))
+  {
+    res= 1;
+    goto err;
+  }
+  while (list->name)
+    res|= insert_dynamic(&all_status_vars, (gptr)list++);
+  res|= insert_dynamic(&all_status_vars, (gptr)list); // appending NULL-element
+  all_status_vars.elements--; // but next insert_dynamic should overwite it
+  if (status_vars_inited)
+    sort_dynamic(&all_status_vars, show_var_cmp);
+err:
+  if (status_vars_inited)
+    pthread_mutex_unlock(&LOCK_status);
+  return res;
+}
+
+/*
+  Make all_status_vars[] usable for SHOW STATUS
+
+  NOTE
+    See add_status_vars(). Before init_status_vars() call, add_status_vars()
+    works in a special fast "startup" mode. Thus init_status_vars()
+    should be called as late as possible but before enabling multi-threading.
+*/
+void init_status_vars()
+{
+  status_vars_inited=1;
+  sort_dynamic(&all_status_vars, show_var_cmp);
+}
+
+/*
+  catch-all cleanup function, cleans up everything no matter what
+
+  DESCRIPTION
+    This function is not strictly required if all add_to_status/
+    remove_status_vars are properly paired, but it's a safety measure that
+    deletes everything from the all_status_vars[] even if some
+    remove_status_vars were forgotten
+*/
+void free_status_vars()
+{
+  delete_dynamic(&all_status_vars);
+}
+
+/*
+  Removes an array of SHOW_VAR entries from the output of SHOW STATUS
+
+  SYNOPSIS
+    remove_status_vars(SHOW_VAR *list)
+    list - an array of SHOW_VAR entries to remove to all_status_vars
+           the last entry must be {0,0,SHOW_UNDEF}
+
+  NOTE
+    there's lots of room for optimizing this, especially in non-sorted mode,
+    but nobody cares - it may be called only in case of failed plugin
+    initialization in the mysqld startup.
+
+*/
+void remove_status_vars(SHOW_VAR *list)
+{
+  if (status_vars_inited)
+  {
+    pthread_mutex_lock(&LOCK_status);
+    SHOW_VAR *all= dynamic_element(&all_status_vars, 0, SHOW_VAR *);
+    int a= 0, b= all_status_vars.elements, c= (a+b)/2, res;
+
+    for (; list->name; list++)
+    {
+      for (a= 0, b= all_status_vars.elements; b-a > 1; c= (a+b)/2)
+      {
+        res= show_var_cmp(list, all+c);
+        if (res < 0)
+          b= c;
+        else if (res > 0)
+          a= c;
+        else break;
+      }
+      if (res == 0)
+        all[c].type= SHOW_UNDEF;
+    }
+    shrink_var_array(&all_status_vars);
+    pthread_mutex_unlock(&LOCK_status);
+  }
+  else
+  {
+    SHOW_VAR *all= dynamic_element(&all_status_vars, 0, SHOW_VAR *);
+    int i;
+    for (; list->name; list++)
+    {
+      for (i= 0; i < all_status_vars.elements; i++)
+      {
+        if (show_var_cmp(list, all+i))
+          continue;
+        all[i].type= SHOW_UNDEF;
+        break;
+      }
+    }
+    shrink_var_array(&all_status_vars);
+  }
+}
+
 static bool show_status_array(THD *thd, const char *wild,
-                              show_var_st *variables,
+                              SHOW_VAR *variables,
                               enum enum_var_type value_type,
                               struct system_status_var *status_var,
                               const char *prefix, TABLE *table)
@@ -1527,13 +1682,15 @@ static bool show_status_array(THD *thd, const char *wild,
   char name_buffer[80];
   int len;
   LEX_STRING null_lex_str;
-  struct show_var_st tmp, *var;
+  SHOW_VAR tmp, *var;
   DBUG_ENTER("show_status_array");
 
   null_lex_str.str= 0;				// For sys_var->value_ptr()
   null_lex_str.length= 0;
 
   prefix_end=strnmov(name_buffer, prefix, sizeof(name_buffer)-1);
+  if (*prefix)
+    *prefix_end++= '_';
   len=name_buffer + sizeof(name_buffer) - prefix_end;
 
   for (; variables->name; variables++)
@@ -1541,13 +1698,17 @@ static bool show_status_array(THD *thd, const char *wild,
     strnmov(prefix_end, variables->name, len);
     name_buffer[sizeof(name_buffer)-1]=0;       /* Safety */
 
+    /*
+      if var->type is SHOW_FUNC, call the function.
+      Repeat as necessary, if new var is again SHOW_FUNC
+    */
     for (var=variables; var->type == SHOW_FUNC; var= &tmp)
-      ((show_var_func)(var->value))(thd, &tmp, buff);
+      ((mysql_show_var_func)(var->value))(thd, &tmp, buff);
 
     SHOW_TYPE show_type=var->type;
     if (show_type == SHOW_ARRAY)
     {
-      show_status_array(thd, wild, (show_var_st *) var->value,
+      show_status_array(thd, wild, (SHOW_VAR *) var->value,
                         value_type, status_var, name_buffer, table);
     }
     else
@@ -1578,11 +1739,10 @@ static bool show_status_array(THD *thd, const char *wild,
           break;
         }
         case SHOW_LONG_STATUS:
-        case SHOW_LONG_CONST_STATUS:
           value= ((char *) status_var + (ulong) value);
           /* fall through */
         case SHOW_LONG:
-        case SHOW_LONG_CONST:
+        case SHOW_LONG_NOFLUSH: // the difference lies in refresh_status()
           end= int10_to_str(*(long*) value, buff, 10);
           break;
         case SHOW_LONGLONG:
@@ -1597,7 +1757,6 @@ static bool show_status_array(THD *thd, const char *wild,
         case SHOW_MY_BOOL:
           end= strmov(buff, *(my_bool*) value ? "ON" : "OFF");
           break;
-        case SHOW_INT_CONST:
         case SHOW_INT:
           end= int10_to_str((long) *(uint32*) value, buff, 10);
           break;
@@ -1623,7 +1782,6 @@ static bool show_status_array(THD *thd, const char *wild,
           break;
         }
         case SHOW_KEY_CACHE_LONG:
-        case SHOW_KEY_CACHE_CONST_LONG:
           value= (char*) dflt_key_cache + (ulong)value;
           end= int10_to_str(*(long*) value, buff, 10);
           break;
@@ -1632,9 +1790,10 @@ static bool show_status_array(THD *thd, const char *wild,
 	  end= longlong10_to_str(*(longlong*) value, buff, 10);
 	  break;
         case SHOW_UNDEF:
-        case SHOW_SYS:
-          break;					// Return empty string
+          break;                                        // Return empty string
+        case SHOW_SYS:                                  // Cannot happen
         default:
+          DBUG_ASSERT(0);
           break;
         }
         restore_record(table, s->default_values);
@@ -3357,7 +3516,7 @@ int fill_variables(THD *thd, TABLE_LIST *tables, COND *cond)
   LEX *lex= thd->lex;
   const char *wild= lex->wild ? lex->wild->ptr() : NullS;
   pthread_mutex_lock(&LOCK_global_system_variables);
-  res= show_status_array(thd, wild, init_vars, 
+  res= show_status_array(thd, wild, init_vars,
                          lex->option_type, 0, "", tables->table);
   pthread_mutex_unlock(&LOCK_global_system_variables);
   DBUG_RETURN(res);
@@ -3374,8 +3533,10 @@ int fill_status(THD *thd, TABLE_LIST *tables, COND *cond)
   pthread_mutex_lock(&LOCK_status);
   if (lex->option_type == OPT_GLOBAL)
     calc_sum_of_all_status(&tmp);
-  res= show_status_array(thd, wild, status_vars, OPT_GLOBAL,
-                         (lex->option_type == OPT_GLOBAL ? 
+  res= show_status_array(thd, wild,
+                         (SHOW_VAR *)all_status_vars.buffer,
+                         OPT_GLOBAL,
+                         (lex->option_type == OPT_GLOBAL ?
                           &tmp: &thd->status_var), "",tables->table);
   pthread_mutex_unlock(&LOCK_status);
   DBUG_RETURN(res);
@@ -4146,7 +4307,7 @@ ST_FIELD_INFO plugin_fields_info[]=
   {"PLUGIN_NAME", NAME_LEN, MYSQL_TYPE_STRING, 0, 0, "Name"},
   {"PLUGIN_VERSION", 20, MYSQL_TYPE_STRING, 0, 0, 0},
   {"PLUGIN_STATUS", 10, MYSQL_TYPE_STRING, 0, 0, "Status"},
-  {"PLUGIN_TYPE", 10, MYSQL_TYPE_STRING, 0, 0, "Type"},
+  {"PLUGIN_TYPE", 80, MYSQL_TYPE_STRING, 0, 0, "Type"},
   {"PLUGIN_TYPE_VERSION", 20, MYSQL_TYPE_STRING, 0, 0, 0},
   {"PLUGIN_LIBRARY", NAME_LEN, MYSQL_TYPE_STRING, 0, 1, "Library"},
   {"PLUGIN_LIBRARY_VERSION", 20, MYSQL_TYPE_STRING, 0, 1, 0},

sql/structs.h

@@ -169,32 +169,11 @@ typedef struct st_known_date_time_format {
   const char *time_format;
 } KNOWN_DATE_TIME_FORMAT;
 
-
-enum SHOW_TYPE
-{
-  SHOW_UNDEF,
-  SHOW_LONG, SHOW_LONGLONG, SHOW_INT, SHOW_CHAR, SHOW_CHAR_PTR,
-  SHOW_DOUBLE_STATUS, SHOW_BOOL, SHOW_MY_BOOL,
-  SHOW_LONG_CONST, SHOW_INT_CONST, SHOW_HAVE, SHOW_SYS, SHOW_HA_ROWS,
-  SHOW_ARRAY, SHOW_FUNC,
-  SHOW_KEY_CACHE_LONG, SHOW_KEY_CACHE_CONST_LONG, SHOW_KEY_CACHE_LONGLONG,
-  SHOW_LONG_STATUS, SHOW_LONG_CONST_STATUS
-};
-
 enum SHOW_COMP_OPTION { SHOW_OPTION_YES, SHOW_OPTION_NO, SHOW_OPTION_DISABLED};
 
 extern const char *show_comp_option_name[];
 
-typedef int *(*update_var)(THD *, struct show_var_st *);
-
-typedef struct show_var_st {
-  const char *name;
-  char *value;
-  SHOW_TYPE type;
-} SHOW_VAR;
-
-#define SHOW_VAR_FUNC_BUFF_SIZE 1024
-typedef int (*show_var_func)(THD *, struct show_var_st *, char *);
+typedef int *(*update_var)(THD *, struct st_mysql_show_var *);
 
 typedef struct	st_lex_user {
   LEX_STRING user, host, password;