Bug#16461: connection_id() does not work properly inside trigger

CONNECTION_ID() was implemented as a constant Item, i.e. an instance of
Item_static_int_func class holding value computed at creation time.
Since Items are created on parsing, and trigger statements are parsed
on table open, the first connection to open a particular table would
effectively set its own CONNECTION_ID() inside trigger statements for
that table.

Re-implement CONNECTION_ID() as a class derived from Item_int_func, and
compute connection_id on every call to fix_fields().


mysql-test/r/trigger.result:
  Add result for bug#16461.
mysql-test/t/trigger.test:
  Add test case for bug#16461.
sql/item.cc:
  Remove now unused class Item_static_int_func.
sql/item.h:
  Remove now unused class Item_static_int_func.
sql/item_create.cc:
  Use new implementation of CONNECTION_ID().
sql/item_func.cc:
  Re-implement CONNECTION_ID() as Item_func_connection_id
  (was Item_static_int_func).  Set max_length to 10, as it was before.
  Compute connection_id dynamically on every call to fix_fields().
sql/item_func.h:
  Re-implement CONNECTION_ID() as Item_func_connection_id
  (was Item_static_int_func).

1 files changed, 12 insertions, 0 deletions

diff --git a/sql/item_func.h b/sql/item_func.h
index ccbbbab1df4..ed5924e8fe1 100644
--- a/sql/item_func.h
+++ b/sql/item_func.h
@@ -279,6 +279,18 @@ public:
 };
 
 
+class Item_func_connection_id :public Item_int_func
+{
+  longlong value;
+
+public:
+  const char *func_name() const { return "connection_id"; }
+  void fix_length_and_dec();
+  bool fix_fields(THD *thd, Item **ref);
+  longlong val_int() { DBUG_ASSERT(fixed == 1); return value; }
+};
+
+
 class Item_func_signed :public Item_int_func
 {
 public: