Changing the state of whether we're recording profiling information

halfway through a query (as happens in "SET SESSION PROFILING = ...")
has a few side-effects, the worst of which is a memory leak for
prepared statements, which poke directly from the parser into the 
profiling code (we don't have the query text when we need it) and 
that overwrites a pointer to heap-allocated memory when the previous
statement turns on profiling.

Instead, now set a flag when we begin a new statement that tracks 
whether profiling is on _at the start_ of the query.  Use that to
track whether we gather info.

Additionally, use that AND use the state of the profiling variable
after the end of a query to know whether to store information about 
the query that just finished.


mysql-test/r/profiling.result:
  Testing whether profiling is on at the beginning of a query and at
  the end of a query makes "SET SESSION PROFILING = ..." statements
  disappear from the profiling.  They were never reliable before.
sql/sql_profile.cc:
  Check to see if profiling was enabled at the beginning of this query
  before trying to store query_source.  This avoids a memory leak for
  prepared statements, which get here by direct means.
  
  If profiling was toggled in this query, then don't store this query
  profile.
sql/sql_profile.h:
  Keep track of whether profiling is on.

3 files changed, 142 insertions, 130 deletions

diff --git a/mysql-test/r/profiling.result b/mysql-test/r/profiling.result
index 50b6fff82b8..9f478d68b8d 100644
--- a/mysql-test/r/profiling.result
+++ b/mysql-test/r/profiling.result
@@ -69,34 +69,33 @@ big_string
 012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890
 show profiles;
 Query_ID	Duration	Query
-1	#	set session profiling = ON
-2	#	set session profiling_history_size=30
-3	#	show session variables like 'profil%'
-4	#	select @@profiling
-5	#	create table t1 (
+1	#	set session profiling_history_size=30
+2	#	show session variables like 'profil%'
+3	#	select @@profiling
+4	#	create table t1 (
 a int,
 b int
 )
-6	#	insert into t1 values (1,1), (2,null), (3, 4)
-7	#	insert into t1 values (5,1), (6,null), (7, 4)
-8	#	insert into t1 values (1,1), (2,null), (3, 4)
-9	#	insert into t1 values (5,1), (6,null), (7, 4)
-10	#	select max(x) from (select sum(a) as x from t1 group by b) as teeone
-11	#	insert into t1 select * from t1
-12	#	select count(*) from t1
+5	#	insert into t1 values (1,1), (2,null), (3, 4)
+6	#	insert into t1 values (5,1), (6,null), (7, 4)
+7	#	insert into t1 values (1,1), (2,null), (3, 4)
+8	#	insert into t1 values (5,1), (6,null), (7, 4)
+9	#	select max(x) from (select sum(a) as x from t1 group by b) as teeone
+10	#	insert into t1 select * from t1
+11	#	select count(*) from t1
+12	#	insert into t1 select * from t1
 13	#	insert into t1 select * from t1
 14	#	insert into t1 select * from t1
-15	#	insert into t1 select * from t1
-16	#	select count(*) from t1
+15	#	select count(*) from t1
+16	#	insert into t1 select * from t1
 17	#	insert into t1 select * from t1
 18	#	insert into t1 select * from t1
-19	#	insert into t1 select * from t1
-20	#	select count(*) from t1
-21	#	select sum(a) from t1
-22	#	select sum(a) from t1 group by b
-23	#	select sum(a) + sum(b) from t1 group by b
-24	#	select max(x) from (select sum(a) as x from t1 group by b) as teeone
-25	#	select '0123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345
+19	#	select count(*) from t1
+20	#	select sum(a) from t1
+21	#	select sum(a) from t1 group by b
+22	#	select sum(a) + sum(b) from t1 group by b
+23	#	select max(x) from (select sum(a) as x from t1 group by b) as teeone
+24	#	select '0123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345
 show profile for query 15;
 show profile cpu for query 15;
 show profile cpu, block io for query 15;
@@ -131,36 +130,36 @@ insert into t2 values (1), (2), (3);
 insert into t3 values (1), (2), (3);
 show profiles;
 Query_ID	Duration	Query
-11	#	insert into t1 select * from t1
-12	#	select count(*) from t1
+10	#	insert into t1 select * from t1
+11	#	select count(*) from t1
+12	#	insert into t1 select * from t1
 13	#	insert into t1 select * from t1
 14	#	insert into t1 select * from t1
-15	#	insert into t1 select * from t1
-16	#	select count(*) from t1
+15	#	select count(*) from t1
+16	#	insert into t1 select * from t1
 17	#	insert into t1 select * from t1
 18	#	insert into t1 select * from t1
-19	#	insert into t1 select * from t1
-20	#	select count(*) from t1
-21	#	select sum(a) from t1
-22	#	select sum(a) from t1 group by b
-23	#	select sum(a) + sum(b) from t1 group by b
-24	#	select max(x) from (select sum(a) as x from t1 group by b) as teeone
-25	#	select '0123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345
-26	#	select * from information_schema.profiling
-27	#	select query_id, state, duration from information_schema.profiling
-28	#	select query_id, sum(duration) from information_schema.profiling group by query_id
-29	#	select query_id, count(*) from information_schema.profiling group by query_id
-30	#	select sum(duration) from information_schema.profiling
-31	#	select query_id, count(*), sum(duration) from information_schema.profiling group by query_id
-32	#	select CPU_user, CPU_system, Context_voluntary, Context_involuntary, Block_ops_in, Block_ops_out, Messages_sent, Messages_received, Page_faults_major, Page_faults_minor, Swaps, Source_function, Source_file, Source_line from information_schema.profiling
-33	#	drop table if exists t1, t2, t3
-34	#	SHOW WARNINGS
-35	#	create table t1 (id int )
-36	#	create table t2 (id int not null)
-37	#	create table t3 (id int not null primary key)
-38	#	insert into t1 values (1), (2), (3)
-39	#	insert into t2 values (1), (2), (3)
-40	#	insert into t3 values (1), (2), (3)
+19	#	select count(*) from t1
+20	#	select sum(a) from t1
+21	#	select sum(a) from t1 group by b
+22	#	select sum(a) + sum(b) from t1 group by b
+23	#	select max(x) from (select sum(a) as x from t1 group by b) as teeone
+24	#	select '0123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345
+25	#	select * from information_schema.profiling
+26	#	select query_id, state, duration from information_schema.profiling
+27	#	select query_id, sum(duration) from information_schema.profiling group by query_id
+28	#	select query_id, count(*) from information_schema.profiling group by query_id
+29	#	select sum(duration) from information_schema.profiling
+30	#	select query_id, count(*), sum(duration) from information_schema.profiling group by query_id
+31	#	select CPU_user, CPU_system, Context_voluntary, Context_involuntary, Block_ops_in, Block_ops_out, Messages_sent, Messages_received, Page_faults_major, Page_faults_minor, Swaps, Source_function, Source_file, Source_line from information_schema.profiling
+32	#	drop table if exists t1, t2, t3
+33	#	SHOW WARNINGS
+34	#	create table t1 (id int )
+35	#	create table t2 (id int not null)
+36	#	create table t3 (id int not null primary key)
+37	#	insert into t1 values (1), (2), (3)
+38	#	insert into t2 values (1), (2), (3)
+39	#	insert into t3 values (1), (2), (3)
 select * from t1;
 id
 1
@@ -168,36 +167,36 @@ id
 3
 show profiles;
 Query_ID	Duration	Query
-12	#	select count(*) from t1
+11	#	select count(*) from t1
+12	#	insert into t1 select * from t1
 13	#	insert into t1 select * from t1
 14	#	insert into t1 select * from t1
-15	#	insert into t1 select * from t1
-16	#	select count(*) from t1
+15	#	select count(*) from t1
+16	#	insert into t1 select * from t1
 17	#	insert into t1 select * from t1
 18	#	insert into t1 select * from t1
-19	#	insert into t1 select * from t1
-20	#	select count(*) from t1
-21	#	select sum(a) from t1
-22	#	select sum(a) from t1 group by b
-23	#	select sum(a) + sum(b) from t1 group by b
-24	#	select max(x) from (select sum(a) as x from t1 group by b) as teeone
-25	#	select '0123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345
-26	#	select * from information_schema.profiling
-27	#	select query_id, state, duration from information_schema.profiling
-28	#	select query_id, sum(duration) from information_schema.profiling group by query_id
-29	#	select query_id, count(*) from information_schema.profiling group by query_id
-30	#	select sum(duration) from information_schema.profiling
-31	#	select query_id, count(*), sum(duration) from information_schema.profiling group by query_id
-32	#	select CPU_user, CPU_system, Context_voluntary, Context_involuntary, Block_ops_in, Block_ops_out, Messages_sent, Messages_received, Page_faults_major, Page_faults_minor, Swaps, Source_function, Source_file, Source_line from information_schema.profiling
-33	#	drop table if exists t1, t2, t3
-34	#	SHOW WARNINGS
-35	#	create table t1 (id int )
-36	#	create table t2 (id int not null)
-37	#	create table t3 (id int not null primary key)
-38	#	insert into t1 values (1), (2), (3)
-39	#	insert into t2 values (1), (2), (3)
-40	#	insert into t3 values (1), (2), (3)
-41	#	select * from t1
+19	#	select count(*) from t1
+20	#	select sum(a) from t1
+21	#	select sum(a) from t1 group by b
+22	#	select sum(a) + sum(b) from t1 group by b
+23	#	select max(x) from (select sum(a) as x from t1 group by b) as teeone
+24	#	select '0123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345
+25	#	select * from information_schema.profiling
+26	#	select query_id, state, duration from information_schema.profiling
+27	#	select query_id, sum(duration) from information_schema.profiling group by query_id
+28	#	select query_id, count(*) from information_schema.profiling group by query_id
+29	#	select sum(duration) from information_schema.profiling
+30	#	select query_id, count(*), sum(duration) from information_schema.profiling group by query_id
+31	#	select CPU_user, CPU_system, Context_voluntary, Context_involuntary, Block_ops_in, Block_ops_out, Messages_sent, Messages_received, Page_faults_major, Page_faults_minor, Swaps, Source_function, Source_file, Source_line from information_schema.profiling
+32	#	drop table if exists t1, t2, t3
+33	#	SHOW WARNINGS
+34	#	create table t1 (id int )
+35	#	create table t2 (id int not null)
+36	#	create table t3 (id int not null primary key)
+37	#	insert into t1 values (1), (2), (3)
+38	#	insert into t2 values (1), (2), (3)
+39	#	insert into t3 values (1), (2), (3)
+40	#	select * from t1
 This ^^ should end in "select * from t1;"
 delete from t1;
 insert into t1 values (1), (2), (3);
@@ -212,72 +211,72 @@ id
 3
 show profiles;
 Query_ID	Duration	Query
-16	#	select count(*) from t1
+15	#	select count(*) from t1
+16	#	insert into t1 select * from t1
 17	#	insert into t1 select * from t1
 18	#	insert into t1 select * from t1
-19	#	insert into t1 select * from t1
-20	#	select count(*) from t1
-21	#	select sum(a) from t1
-22	#	select sum(a) from t1 group by b
-23	#	select sum(a) + sum(b) from t1 group by b
-24	#	select max(x) from (select sum(a) as x from t1 group by b) as teeone
-25	#	select '0123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345
-26	#	select * from information_schema.profiling
-27	#	select query_id, state, duration from information_schema.profiling
-28	#	select query_id, sum(duration) from information_schema.profiling group by query_id
-29	#	select query_id, count(*) from information_schema.profiling group by query_id
-30	#	select sum(duration) from information_schema.profiling
-31	#	select query_id, count(*), sum(duration) from information_schema.profiling group by query_id
-32	#	select CPU_user, CPU_system, Context_voluntary, Context_involuntary, Block_ops_in, Block_ops_out, Messages_sent, Messages_received, Page_faults_major, Page_faults_minor, Swaps, Source_function, Source_file, Source_line from information_schema.profiling
-33	#	drop table if exists t1, t2, t3
-34	#	SHOW WARNINGS
-35	#	create table t1 (id int )
-36	#	create table t2 (id int not null)
-37	#	create table t3 (id int not null primary key)
-38	#	insert into t1 values (1), (2), (3)
-39	#	insert into t2 values (1), (2), (3)
-40	#	insert into t3 values (1), (2), (3)
-41	#	select * from t1
-42	#	delete from t1
+19	#	select count(*) from t1
+20	#	select sum(a) from t1
+21	#	select sum(a) from t1 group by b
+22	#	select sum(a) + sum(b) from t1 group by b
+23	#	select max(x) from (select sum(a) as x from t1 group by b) as teeone
+24	#	select '0123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345
+25	#	select * from information_schema.profiling
+26	#	select query_id, state, duration from information_schema.profiling
+27	#	select query_id, sum(duration) from information_schema.profiling group by query_id
+28	#	select query_id, count(*) from information_schema.profiling group by query_id
+29	#	select sum(duration) from information_schema.profiling
+30	#	select query_id, count(*), sum(duration) from information_schema.profiling group by query_id
+31	#	select CPU_user, CPU_system, Context_voluntary, Context_involuntary, Block_ops_in, Block_ops_out, Messages_sent, Messages_received, Page_faults_major, Page_faults_minor, Swaps, Source_function, Source_file, Source_line from information_schema.profiling
+32	#	drop table if exists t1, t2, t3
+33	#	SHOW WARNINGS
+34	#	create table t1 (id int )
+35	#	create table t2 (id int not null)
+36	#	create table t3 (id int not null primary key)
+37	#	insert into t1 values (1), (2), (3)
+38	#	insert into t2 values (1), (2), (3)
+39	#	insert into t3 values (1), (2), (3)
+40	#	select * from t1
+41	#	delete from t1
+42	#	insert into t1 values (1), (2), (3)
 43	#	insert into t1 values (1), (2), (3)
-44	#	insert into t1 values (1), (2), (3)
-45	#	select * from t1
+44	#	select * from t1
 set session profiling = OFF;
 select sum(id) from t1;
 sum(id)
 12
 show profiles;
 Query_ID	Duration	Query
-16	#	select count(*) from t1
+15	#	select count(*) from t1
+16	#	insert into t1 select * from t1
 17	#	insert into t1 select * from t1
 18	#	insert into t1 select * from t1
-19	#	insert into t1 select * from t1
-20	#	select count(*) from t1
-21	#	select sum(a) from t1
-22	#	select sum(a) from t1 group by b
-23	#	select sum(a) + sum(b) from t1 group by b
-24	#	select max(x) from (select sum(a) as x from t1 group by b) as teeone
-25	#	select '0123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345
-26	#	select * from information_schema.profiling
-27	#	select query_id, state, duration from information_schema.profiling
-28	#	select query_id, sum(duration) from information_schema.profiling group by query_id
-29	#	select query_id, count(*) from information_schema.profiling group by query_id
-30	#	select sum(duration) from information_schema.profiling
-31	#	select query_id, count(*), sum(duration) from information_schema.profiling group by query_id
-32	#	select CPU_user, CPU_system, Context_voluntary, Context_involuntary, Block_ops_in, Block_ops_out, Messages_sent, Messages_received, Page_faults_major, Page_faults_minor, Swaps, Source_function, Source_file, Source_line from information_schema.profiling
-33	#	drop table if exists t1, t2, t3
-34	#	SHOW WARNINGS
-35	#	create table t1 (id int )
-36	#	create table t2 (id int not null)
-37	#	create table t3 (id int not null primary key)
-38	#	insert into t1 values (1), (2), (3)
-39	#	insert into t2 values (1), (2), (3)
-40	#	insert into t3 values (1), (2), (3)
-41	#	select * from t1
-42	#	delete from t1
+19	#	select count(*) from t1
+20	#	select sum(a) from t1
+21	#	select sum(a) from t1 group by b
+22	#	select sum(a) + sum(b) from t1 group by b
+23	#	select max(x) from (select sum(a) as x from t1 group by b) as teeone
+24	#	select '0123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345678900123456789001234567890012345
+25	#	select * from information_schema.profiling
+26	#	select query_id, state, duration from information_schema.profiling
+27	#	select query_id, sum(duration) from information_schema.profiling group by query_id
+28	#	select query_id, count(*) from information_schema.profiling group by query_id
+29	#	select sum(duration) from information_schema.profiling
+30	#	select query_id, count(*), sum(duration) from information_schema.profiling group by query_id
+31	#	select CPU_user, CPU_system, Context_voluntary, Context_involuntary, Block_ops_in, Block_ops_out, Messages_sent, Messages_received, Page_faults_major, Page_faults_minor, Swaps, Source_function, Source_file, Source_line from information_schema.profiling
+32	#	drop table if exists t1, t2, t3
+33	#	SHOW WARNINGS
+34	#	create table t1 (id int )
+35	#	create table t2 (id int not null)
+36	#	create table t3 (id int not null primary key)
+37	#	insert into t1 values (1), (2), (3)
+38	#	insert into t2 values (1), (2), (3)
+39	#	insert into t3 values (1), (2), (3)
+40	#	select * from t1
+41	#	delete from t1
+42	#	insert into t1 values (1), (2), (3)
 43	#	insert into t1 values (1), (2), (3)
-44	#	insert into t1 values (1), (2), (3)
-45	#	select * from t1
+44	#	select * from t1
 set session profiling = ON;
 select @@profiling;
 @@profiling
diff --git a/sql/sql_profile.cc b/sql/sql_profile.cc
index 5fd83ce70c6..91b0b062e4f 100644
--- a/sql/sql_profile.cc
+++ b/sql/sql_profile.cc
@@ -168,10 +168,14 @@ QUERY_PROFILE::QUERY_PROFILE(PROFILING *profiling_arg, char *query_source_arg,
 void QUERY_PROFILE::set_query_source(char *query_source_arg, 
                                      uint query_length_arg)
 {
+  if (! profiling->enabled)
+    return;
+
   /* Truncate to avoid DoS attacks. */
   uint length= min(MAX_QUERY_LENGTH, query_length_arg); 
   /* TODO?: Provide a way to include the full text, as in  SHOW PROCESSLIST. */
 
+  DBUG_ASSERT(query_source == NULL);
   if (query_source_arg != NULL)
     query_source= my_strdup_with_length(query_source_arg, length, MYF(0));
 }
@@ -445,7 +449,7 @@ bool QUERY_PROFILE::show(uint options)
 }
 
 PROFILING::PROFILING()
-  :profile_id_counter(1), keeping(1), current(NULL), last(NULL)
+  :profile_id_counter(1), keeping(TRUE), enabled(FALSE), current(NULL), last(NULL)
 {
 }
 
@@ -464,7 +468,7 @@ void PROFILING::status_change(const char *status_arg,
 {
   DBUG_ENTER("PROFILING::status_change");
   
-  if (unlikely((thd->options & OPTION_PROFILING) != 0))
+  if (unlikely(enabled))
   {
     if (unlikely(current == NULL))
       reset();
@@ -499,6 +503,8 @@ void PROFILING::store()
   if (current != NULL)
   {
     if (keeping && 
+        (enabled) &&                                    /* ON at start? */
+        (((thd)->options & OPTION_PROFILING) != 0) &&   /* and ON at end? */
         (current->query_source != NULL) && 
         (current->query_source[0] != '\0') && 
         (!current->entries.is_empty())) 
@@ -517,7 +523,8 @@ void PROFILING::store()
   }
   
   DBUG_ASSERT(current == NULL);
-  current= new QUERY_PROFILE(this, thd->query, thd->query_length);
+  if (enabled)
+    current= new QUERY_PROFILE(this, thd->query, thd->query_length);
 
   DBUG_VOID_RETURN;
 }
@@ -534,7 +541,12 @@ void PROFILING::reset()
   store();
 
   if (likely(((thd)->options & OPTION_PROFILING) == 0))
+  {
+    enabled= FALSE;
     DBUG_VOID_RETURN;
+  }
+  else
+    enabled= TRUE;
 
   if (current != NULL)
     current->reset();
diff --git a/sql/sql_profile.h b/sql/sql_profile.h
index 7913d037551..b82b5ce090c 100644
--- a/sql/sql_profile.h
+++ b/sql/sql_profile.h
@@ -277,6 +277,7 @@ private:
   query_id_t profile_id_counter;     
   THD *thd;
   bool keeping;
+  bool enabled;
 
   QUERY_PROFILE *current;
   QUERY_PROFILE *last;