Bug#47525: MySQL crashed (Federated)

On Mac OS X or Windows, sending a SIGHUP to the server or a
asynchronous flush (triggered by flush_time), would cause the
server to crash.

The problem was that a hook used to detach client API handles
wasn't prepared to handle cases where the thread does not have
a associated session.

The solution is to verify whether the thread has a associated
session before trying to detach a handle.

mysql-test/r/federated_debug.result:
  Add test case result for Bug#47525
mysql-test/t/federated_debug-master.opt:
  Debug point.
mysql-test/t/federated_debug.test:
  Add test case for Bug#47525
sql/slave.cc:
  Check whether a the thread has a associated session.
sql/sql_parse.cc:
  Add debug code to simulate a reload without thread session.

1 files changed, 20 insertions, 0 deletions

diff --git a/sql/sql_parse.cc b/sql/sql_parse.cc
index 65b2a9d60b0..62cca71ee97 100644
--- a/sql/sql_parse.cc
+++ b/sql/sql_parse.cc
@@ -2161,6 +2161,26 @@ bool dispatch_command(enum enum_server_command command, THD *thd,
     if (check_global_access(thd,RELOAD_ACL))
       break;
     mysql_log.write(thd,command,NullS);
+#ifndef DBUG_OFF
+    DBUG_EXECUTE_IF("simulate_detached_thread_refresh",
+                    {
+                      /*
+                        Simulate a reload without a attached thread session.
+                        Provides a environment similar to that of when the
+                        server receives a SIGHUP signal and reloads caches
+                        and flushes tables.
+                      */
+                      bool res;
+                      my_pthread_setspecific_ptr(THR_THD, NULL);
+                      res= reload_acl_and_cache(NULL, options | REFRESH_FAST,
+                                                NULL, &not_used);
+                      my_pthread_setspecific_ptr(THR_THD, thd);
+                      if (!res)
+                        send_ok(thd);
+                      break;
+                    }
+                    );
+#endif
     if (!reload_acl_and_cache(thd, options, (TABLE_LIST*) 0, &not_used))
       send_ok(thd);
     break;