BUG#50364: FLUSH LOGS crashes the server (rpl.rpl_heartbeat_basic

fails in PB sporadically)
      
The IO thread can concurrently access the relay log IO_CACHE
while another thread is performing an FLUSH LOGS procedure.
      
FLUSH LOGS closes and reopens the relay log and while doing so it
(re)initializes its IO_CACHE. During this procedure the IO_CACHE
mutex is also reinitialized, which can cause problems if some
other thread (namely the IO THREAD) is concurrently accessing it
at the time .
      
This patch fixes the problem by extending the interface of the
flush_master_info function to also include a second paramater, 
"need_relay_log_lock", stating whether the thread should grab the 
relay log lock or not before actually flushing the relay log. 
Also, IO thread now calls flush_master_info with this flag set 
when it flushes master info with in the event read_event loop.

Finally, we also increase loop time in rpl_heartbeat_basic test 
case, so that the number of calls to flush logs doubles, stressing
this part of the code a little more.

mysql-test/suite/rpl/t/rpl_heartbeat_basic.test:
  Doubled the number of iterations on the FLUSH LOGS loop by
  doubling the time available to perform all iterations.
sql/repl_failsafe.cc:
  Updating flush_master_info call so that it uses two parameters
  instead of one.
sql/rpl_mi.cc:
  Updating flush_master_info call so that it uses two parameters
  instead of one.
sql/rpl_mi.h:
  Changed flush_master_info interface. Now takes a second parameter
  instead of just one. The second parameter is: need_lock_relay_log.
sql/rpl_rli.cc:
  Small fix in comment.
sql/slave.cc:
  Updating flush_master_info call so that it uses two parameters
  instead of one.
sql/sql_repl.cc:
  Updating flush_master_info call so that it uses two parameters
  instead of one.

1 files changed, 1 insertions, 1 deletions

diff --git a/sql/rpl_rli.cc b/sql/rpl_rli.cc
index 4bbafa0253a..fa979fe9a21 100644
--- a/sql/rpl_rli.cc
+++ b/sql/rpl_rli.cc
@@ -121,7 +121,7 @@ int init_relay_log_info(Relay_log_info* rli,
   /*
     The relay log will now be opened, as a SEQ_READ_APPEND IO_CACHE.
     Note that the I/O thread flushes it to disk after writing every
-    event, in flush_master_info(mi, 1).
+    event, in flush_master_info(mi, 1, ?).
   */
 
   /*