SCRUM

IS_USED_LOCK('lock') implementation

sql/item_create.cc

@@ -475,6 +475,12 @@ Item *create_func_is_free_lock(Item* a)
   return new Item_func_is_free_lock(a);
 }
 
+Item *create_func_is_used_lock(Item* a)
+{
+  current_thd->lex.uncacheable();
+  return new Item_func_is_used_lock(a);
+}
+
 Item *create_func_quote(Item* a)
 {
   return new Item_func_quote(a);

sql/item_create.h

@@ -100,6 +100,7 @@ Item *create_func_version(void);
 Item *create_func_weekday(Item* a);
 Item *create_load_file(Item* a);
 Item *create_func_is_free_lock(Item* a);
+Item *create_func_is_used_lock(Item* a);
 Item *create_func_quote(Item* a);
 
 Item *create_func_geometry_from_text(Item* a);

sql/item_func.cc

@@ -1632,8 +1632,10 @@ class ULL
   bool locked;
   pthread_cond_t cond;
   pthread_t thread;
+  ulong thread_id;
 
-  ULL(const char *key_arg,uint length) :key_length(length),count(1),locked(1)
+  ULL(const char *key_arg,uint length, ulong id) 
+    :key_length(length),count(1),locked(1), thread_id(id)
   {
     key=(char*) my_memdup((byte*) key_arg,length,MYF(0));
     pthread_cond_init(&cond,NULL);
@@ -1837,7 +1839,7 @@ longlong Item_func_get_lock::val_int()
   if (!(ull= ((ULL*) hash_search(&hash_user_locks,(byte*) res->ptr(),
 				 res->length()))))
   {
-    ull=new ULL(res->ptr(),res->length());
+    ull=new ULL(res->ptr(),res->length(), thd->thread_id);
     if (!ull || !ull->initialized())
     {
       delete ull;
@@ -2698,6 +2700,28 @@ longlong Item_func_is_free_lock::val_int()
   return 0;
 }
 
+longlong Item_func_is_used_lock::val_int()
+{
+  String *res=args[0]->val_str(&value);
+  THD *thd=current_thd;
+  ULL *ull;
+
+  null_value=1;
+  if (!res || !res->length())
+    return 0;
+  
+  pthread_mutex_lock(&LOCK_user_locks);
+  ull= (ULL*) hash_search(&hash_user_locks,(byte*) res->ptr(),
+			  res->length());
+  pthread_mutex_unlock(&LOCK_user_locks);
+  if (!ull || !ull->locked)
+    return 0;
+
+  null_value=0;
+  return ull->thread_id;
+}
+
+
 
 /**************************************************************************
   Spatial functions

sql/item_func.h

@@ -1151,6 +1151,16 @@ class Item_func_is_free_lock :public Item_int_func
   void fix_length_and_dec() { decimals=0; max_length=1; maybe_null=1;}
 };
 
+class Item_func_is_used_lock :public Item_int_func
+{
+  String value;
+public:
+  Item_func_is_used_lock(Item *a) :Item_int_func(a) {}
+  longlong val_int();
+  const char *func_name() const { return "is_used_lock"; }
+  void fix_length_and_dec() { decimals=0; max_length=10; maybe_null=1;}
+};
+
 /* For type casts */
 
 enum Item_cast

sql/lex.h

@@ -509,6 +509,7 @@ static SYMBOL sql_functions[] = {
   { "ISEMPTY",		SYM(FUNC_ARG1),0,CREATE_FUNC(create_func_isempty)},
   { "ISNULL",		SYM(FUNC_ARG1),0,CREATE_FUNC(create_func_isnull)},
   { "IS_FREE_LOCK",	SYM(FUNC_ARG1),0,CREATE_FUNC(create_func_is_free_lock)},
+  { "IS_USED_LOCK",	SYM(FUNC_ARG1),0,CREATE_FUNC(create_func_is_used_lock)},
   { "LAST_INSERT_ID",	SYM(LAST_INSERT_ID),0,0},
   { "ISSIMPLE",		SYM(FUNC_ARG1),0,CREATE_FUNC(create_func_issimple)},
   { "LCASE",		SYM(FUNC_ARG1),0,CREATE_FUNC(create_func_lcase)},