WL#1062 "log charset info into all Query_log_event":

we store 7 bytes (1 + 2*3) in every Query_log_event.
In the future if users want binlog optimized for small size and less safe,
we could add --binlog-no-charset (and binlog-no-sql-mode etc): charset info
is something by design optional (even if for now we don't offer possibility to disable it):
it's not a binlog format change.
We try to reduce the number of get_charset() calls in the slave SQL thread to a minimum
by caching the charset read from the previous event (which will often be equal to the one of the current event).
We don't use SET ONE_SHOT for charset-aware repl (we still do for timezones, will be fixed later).
No more errors if one changes the global value of charset vars on master or slave
(as we log charset info in all Query_log_event).
Not fixing Load_log_event as it will be rewritten soon by Dmitri.
Testing how mysqlbinlog behaves in rpl_charset.test.
mysqlbinlog needs to know where charset file is (to be able to convert a charset number found
in binlog (e.g. in User_var_log_event) to a charset name); mysql-test-run needs to pass
the correct value for this option to mysqlbinlog.
Many result udpates (adding charset info into every event shifts log_pos in SHOW BINLOG EVENTS).
Roughly the same job is to be done for timezones :)

1 files changed, 42 insertions, 8 deletions

diff --git a/sql/slave.cc b/sql/slave.cc
index 0c5ebe0744a..380aba6f3b6 100644
--- a/sql/slave.cc
+++ b/sql/slave.cc
@@ -660,13 +660,14 @@ int terminate_slave_thread(THD* thd, pthread_mutex_t* term_lock,
 			   pthread_cond_t* term_cond,
 			   volatile uint *slave_running)
 {
+  DBUG_ENTER("terminate_slave_thread");
   if (term_lock)
   {
     pthread_mutex_lock(term_lock);
     if (!*slave_running)
     {
       pthread_mutex_unlock(term_lock);
-      return ER_SLAVE_NOT_RUNNING;
+      DBUG_RETURN(ER_SLAVE_NOT_RUNNING);
     }
   }
   DBUG_ASSERT(thd != 0);
@@ -678,6 +679,7 @@ int terminate_slave_thread(THD* thd, pthread_mutex_t* term_lock,
 
   while (*slave_running)			// Should always be true
   {
+    DBUG_PRINT("loop", ("killing slave thread"));
     KICK_SLAVE(thd);
     /*
       There is a small chance that slave thread might miss the first
@@ -689,7 +691,7 @@ int terminate_slave_thread(THD* thd, pthread_mutex_t* term_lock,
   }
   if (term_lock)
     pthread_mutex_unlock(term_lock);
-  return 0;
+  DBUG_RETURN(0);
 }
 
 
@@ -1418,13 +1420,20 @@ not always make sense; please check the manual before using it).";
     values of these 2 are never used (new connections don't use them).
     We don't test equality of global collation_database either as it's is
     going to be deprecated (made read-only) in 4.1 very soon.
-    We don't do it for <3.23.57 because masters <3.23.50 hang on
-    SELECT @@unknown_var (BUG#7965 - see changelog of 3.23.50).
+    The test is only relevant if master < 5.0.3 (we'll test only if it's older
+    than the 5 branch; < 5.0.3 was alpha...), as >= 5.0.3 master stores
+    charset info in each binlog event.
+    We don't do it for 3.23 because masters <3.23.50 hang on
+    SELECT @@unknown_var (BUG#7965 - see changelog of 3.23.50). So finally we
+    test only if master is 4.x.
   */
-  if (strncmp(mi->rli.relay_log.description_event_for_queue->server_version,
-              "3.23.57",7) < 0)
+
+  /* redundant with rest of code but safer against later additions */
+  if (*mysql->server_version == '3')
     goto err;
-  if (!mysql_real_query(mysql, "SELECT @@GLOBAL.COLLATION_SERVER", 32) &&
+
+  if ((*mysql->server_version == '4') &&
+      !mysql_real_query(mysql, "SELECT @@GLOBAL.COLLATION_SERVER", 32) &&
       (master_res= mysql_store_result(mysql)))
   {
     if ((master_row= mysql_fetch_row(master_res)) &&
@@ -1447,8 +1456,12 @@ be equal for replication to work";
     such check will broke everything for them. (And now everything will 
     work for them because by default both their master and slave will have 
     'SYSTEM' time zone).
+
+    TODO: when the new replication of timezones is sorted out with Dmitri,
+    change >= '4' to == '4'.
   */
-  if (!mysql_real_query(mysql, "SELECT @@GLOBAL.TIME_ZONE", 25) &&
+  if ((*mysql->server_version >= '4') &&
+      !mysql_real_query(mysql, "SELECT @@GLOBAL.TIME_ZONE", 25) &&
       (master_res= mysql_store_result(mysql)))
   {
     if ((master_row= mysql_fetch_row(master_res)) &&
@@ -2527,6 +2540,7 @@ st_relay_log_info::st_relay_log_info()
 
   bzero((char*) &info_file, sizeof(info_file));
   bzero((char*) &cache_buf, sizeof(cache_buf));
+  cached_charset_invalidate();
   pthread_mutex_init(&run_lock, MY_MUTEX_INIT_FAST);
   pthread_mutex_init(&data_lock, MY_MUTEX_INIT_FAST);
   pthread_mutex_init(&log_space_lock, MY_MUTEX_INIT_FAST);
@@ -3078,6 +3092,24 @@ bool st_relay_log_info::is_until_satisfied()
 }
 
 
+void st_relay_log_info::cached_charset_invalidate()
+{
+  /* Full of zeroes means uninitialized. */
+  bzero(cached_charset, sizeof(cached_charset));
+}
+
+
+bool st_relay_log_info::cached_charset_compare(char *charset)
+{
+  if (bcmp(cached_charset, charset, sizeof(cached_charset)))
+  {
+    memcpy(cached_charset, charset, sizeof(cached_charset));
+    return 1;
+  }
+  return 0;
+}
+
+
 static int exec_relay_log_event(THD* thd, RELAY_LOG_INFO* rli)
 {
   /*
@@ -3722,6 +3754,8 @@ the slave SQL thread with \"SLAVE START\". We stopped at log \
   DBUG_PRINT("info",("Signaling possibly waiting master_pos_wait() functions"));
   pthread_cond_broadcast(&rli->data_cond);
   rli->ignore_log_space_limit= 0; /* don't need any lock */
+  /* we die so won't remember charset - re-update them on next thread start */
+  rli->cached_charset_invalidate();
   rli->save_temporary_tables = thd->temporary_tables;
 
   /*