Save and clear run context before executing a stored function or trigger and restore it afterwards.

This allows us to use statement replication with functions and triggers
The following things are fixed with this patch:
- NOW() and automatic timestamps takes the value from the main event for functions and triggers (which allows these to replicate with statement level logging)
- No side effects for triggers or functions with auto-increment values(), last_insert_id(), rand() or found_rows()
- Triggers can't return result sets

Fixes bugs:
#12480: NOW() is not constant in a trigger
#12481: Using NOW() in a stored function breaks statement based replication
#12482: Triggers has side effects with auto_increment values
#11587: trigger causes lost connection error


mysql-test/r/trigger.result:
  Added test fpr big
mysql-test/t/sp-error.test:
  Changed error message numbers
mysql-test/t/trigger.test:
  Added test for trigger returning result (#11587)
sql/item_func.cc:
  Store the first used seed value for RAND() value.
  (This makes rand() replicatable in functions and triggers)
  Save and clear run context before executing a stored function and restore it afterwards.
  This removes side effects of stored functions for RAND(), auto-increment values and NOW() and makes most stored function replicatable
sql/share/errmsg.txt:
  Reuse error message also for triggers
sql/sp_head.cc:
  If in function or trigger, don't change value of NOW()
  (This allows us to use statement replication with functions that directly or indirectly uses timestamps)
sql/sql_class.cc:
  Added framework for storing and retrieving run context while exceuting triggers or stored functions.
sql/sql_class.h:
  Added framework for storing and retrieving run context while exceuting triggers or stored functions.
sql/sql_parse.cc:
  If in function or trigger, don't change value of NOW()
  (This allows us to use statement replication with functions that directly or indirectly uses timestamps)
sql/sql_trigger.cc:
  Moved process_triggers function from sql_trigger.h
  Use reset/restore sub_statement_state while executing triggers to avoid side effects and make them replicatable
sql/sql_trigger.h:
  Moved process_triggers function from sql_trigger.h
  Use reset/restore sub_statement_state while executing triggers to avoid side effects and make them replicatable
sql/sql_yacc.yy:
  Give error message if trigger can return a result set (Bug #11587)
tests/fork_big2.pl:
  Removed return from end of lines
mysql-test/r/rpl_trigger.result:
  New BitKeeper file ``mysql-test/r/rpl_trigger.result''
mysql-test/t/rpl_trigger.test:
  New BitKeeper file ``mysql-test/t/rpl_trigger.test''

mysql-test/t/rpl_trigger.test

@@ -0,0 +1,117 @@
+#
+# Test of triggers with replication
+#
+
+source include/master-slave.inc;
+
+#
+# #12482: Triggers has side effects with auto_increment values
+#
+
+create table t1 (a int auto_increment, primary key (a), b int, rand_value double not null);
+create table t2 (a int auto_increment, primary key (a), b int);
+create table t3 (a int auto_increment, primary key (a), name varchar(64) not null, old_a int, old_b int, rand_value double not null);
+
+delimiter |;
+create trigger t1 before insert on t1 for each row
+begin
+ insert into t3 values (NULL, "t1", new.a, new.b, rand());
+end|
+
+create trigger t2 after insert on t2 for each row
+begin
+ insert into t3 values (NULL, "t2", new.a, new.b, rand());
+end|
+delimiter ;|
+
+insert into t3 values(100,"log",0,0,0);
+
+# Ensure we always have same random numbers
+SET @@RAND_SEED1=658490765, @@RAND_SEED2=635893186;
+
+# Emulate that we have rows 2-9 deleted on the slave
+insert into t1 values(1,1,rand()),(NULL,2,rand());
+insert into t2 (b) values(last_insert_id());
+insert into t2 values(3,0),(NULL,0);
+insert into t2 values(NULL,0),(500,0);
+
+select a,b, truncate(rand_value,4) from t1;
+select * from t2;
+select a,name, old_a, old_b, truncate(rand_value,4) from t3;
+save_master_pos;
+connection slave;
+sync_with_master;
+--disable_query_log
+select "--- On slave --" as "";
+--enable_query_log
+select a,b, truncate(rand_value,4) from t1;
+select * from t2;
+select a,name, old_a, old_b, truncate(rand_value,4) from t3;
+connection master;
+drop table t1,t2,t3;
+
+#
+# #12480: NOW() is not constant in a trigger
+# #12481: Using NOW() in a stored function breaks statement based replication
+#
+
+# Start by getting a lock on 'bug12480' to be able to use get_lock() as sleep()
+connect (con2,localhost,root,,);
+connection con2;
+select get_lock("bug12480",2);
+connection default;
+
+create table t1 (a datetime,b  datetime, c datetime);
+--ignore_warnings
+drop function if exists bug12480;
+--enable_warnings
+
+delimiter |;
+
+create function bug12480() returns datetime
+begin
+  set @a=get_lock("bug12480",2);
+  return now();
+end|
+
+create trigger t1_first before insert on t1
+for each row begin
+  set @a=get_lock("bug12480",2);
+  set new.b= now();
+  set new.c= bug12480();
+end
+|
+
+delimiter ;|
+insert into t1 set a = now();
+select a=b && a=c from t1;
+let $time=`select a from t1`;
+
+connection slave;
+sync_with_master;
+--disable_query_log
+select "--- On slave --" as "";
+--enable_query_log
+select a=b && a=c from t1;
+--disable_query_log
+eval select a='$time' as 'test' from t1;
+--enable_query_log
+
+connection master;
+disconnect con2;
+
+truncate table t1;
+drop trigger t1_first;
+
+insert into t1 values ("2003-03-03","2003-03-03","2003-03-03"),(bug12480(),bug12480(),bug12480()),(now(),now(),now());
+select a=b && a=c from t1;
+
+drop function bug12480;
+drop table t1;
+
+#
+# End of test
+#
+save_master_pos;
+connection slave;
+sync_with_master;