MDEV-21599 - plugins.server_audit fails sporadically in buildbot

Fixed a couple of race conditions in the test case to ensure stable order
of events. Also removed all sleeps. Test execution time is down from 18s
to 0.15s.

On disconnect audit event is triggered after control is returned to
mysqltest client. Which means mysqltest may issue more commands
concurrently before disconnect is actually logged.

Similar problem happens with regular query execution: an event is
triggered after control is returner to the client. Which may end
up with unstable order of events in different connections.

Delayed insert rows are enqueued separately and can either be combined
into single event or go as separate events. Reduced number of inserted
rows to 1 to stabilize result.

Also backported 2b3f6ab4 from 10.5.

mysql-test/include/wait_for_line_count_in_file.inc

+perl;
+  use strict;
+  use Time::HiRes qw(sleep);
+  my $search_count= $ENV{'SEARCH_COUNT'} or die "SEARCH_COUNT not set";
+  my $search_file= $ENV{'SEARCH_FILE'} or die "SEARCH_FILE not set";
+  my $wait_counter= 100; # 10 seconds
+  while (1)
+  {
+    my $cnt= 0;
+    open(FILE, $search_file) or die("Unable to open '$search_file': $!\n");
+    $cnt++ while (<FILE>);
+    close(FILE);
+    last if ($cnt == $search_count);
+    $wait_counter-- or
+      die "Timeout waiting for $search_count lines in $search_file\n";
+    sleep(0.1);
+  }
+EOF

mysql-test/suite/plugins/r/server_audit.result

@@ -32,7 +32,6 @@ show variables like 'server_audit_excl_users';
 Variable_name	Value
 server_audit_excl_users	
 connect  con1,localhost,root,,mysql;
-connection default;
 disconnect con1;
 connect(localhost,no_such_user,,mysql,MASTER_PORT,MASTER_SOCKET);
 connect  con1,localhost,no_such_user,,mysql;
@@ -99,7 +98,6 @@ set global server_audit_mode=1;
 set global server_audit_events='';
 create database sa_db;
 connect  con1,localhost,root,,test;
-connection con1;
 create table t1 (id2 int);
 insert into t1 values (1), (2);
 select * from t1;
@@ -112,8 +110,8 @@ create table sa_t1(id int);
 insert into sa_t1 values (1), (2);
 drop table sa_t1;
 drop database sa_db;
-connection default;
 disconnect con1;
+connection default;
 create database sa_db;
 use sa_db;
 CREATE USER u1 IDENTIFIED BY 'pwd-123';
@@ -219,7 +217,7 @@ grant all on sa_db.* to user1@localhost;
 connect  cn1,localhost,user1,,sa_db;
 connection cn1;
 create table t1(id int) engine=myisam;
-insert delayed into t1 values (1), (2);
+insert delayed into t1 values (1);
 connection default;
 # Waiting until INSERT DELAYED thread does the insert.
 drop table t1;

mysql-test/suite/plugins/t/server_audit.test

@@ -5,6 +5,13 @@ if (!$SERVER_AUDIT_SO) {
   skip No SERVER_AUDIT plugin;
 }
 
+# An unfortunate wait for check-testcase.test to complete disconnect.
+let count_sessions= 1;
+source include/wait_until_count_sessions.inc;
+
+let $MYSQLD_DATADIR= `SELECT @@datadir`;
+let SEARCH_FILE= $MYSQLD_DATADIR/server_audit.log;
+
 install plugin server_audit soname 'server_audit';
 
 show variables like 'server_audit%';
@@ -20,18 +27,21 @@ show variables like 'server_audit_incl_users';
 --error ER_WRONG_VALUE_FOR_VAR
 set global server_audit_excl_users= repeat("'root',", 10000);
 show variables like 'server_audit_excl_users';
+let SEARCH_COUNT= 5;
+source include/wait_for_line_count_in_file.inc;
 
---sleep 2
 connect (con1,localhost,root,,mysql);
-connection default;
 disconnect con1;
---sleep 2
---sleep 2
+let SEARCH_COUNT= 7;
+source include/wait_for_line_count_in_file.inc;
+
 --replace_result $MASTER_MYSOCK MASTER_SOCKET $MASTER_MYPORT MASTER_PORT
 --error ER_ACCESS_DENIED_ERROR
 connect (con1,localhost,no_such_user,,mysql);
+let SEARCH_COUNT= 9;
+source include/wait_for_line_count_in_file.inc;
+
 connection default;
---sleep 2
 set global server_audit_incl_users='odin, dva, tri';
 create table t1 (id int);
 set global server_audit_incl_users='odin, root, dva, tri';
@@ -61,11 +71,10 @@ show variables like 'server_audit%';
 set global server_audit_mode=1;
 set global server_audit_events='';
 create database sa_db;
---sleep 2
+let SEARCH_COUNT= 41;
+source include/wait_for_line_count_in_file.inc;
+
 connect (con1,localhost,root,,test);
-connection con1;
---sleep 2
---sleep 2
 create table t1 (id2 int);
 insert into t1 values (1), (2);
 select * from t1;
@@ -75,10 +84,11 @@ create table sa_t1(id int);
 insert into sa_t1 values (1), (2);
 drop table sa_t1;
 drop database sa_db;
-connection default;
 disconnect con1;
---sleep 2
---sleep 2
+let SEARCH_COUNT= 68;
+source include/wait_for_line_count_in_file.inc;
+
+connection default;
 create database sa_db;
 use sa_db;
 CREATE USER u1 IDENTIFIED BY 'pwd-123';
@@ -146,10 +156,10 @@ connect (cn1,localhost,user1,,sa_db);
 connection cn1;
 
 create table t1(id int) engine=myisam;
-insert delayed into t1 values (1), (2);
+insert delayed into t1 values (1);
 connection default;
 --echo # Waiting until INSERT DELAYED thread does the insert.
-let $wait_condition= SELECT COUNT(*) = 2 FROM t1;
+let $wait_condition= SELECT COUNT(*) = 1 FROM t1;
 --source include/wait_condition.inc
 drop table t1;
 
@@ -157,6 +167,9 @@ set global server_audit_logging= off;
 set global server_audit_incl_users='root';
 set global server_audit_logging= on;
 disconnect cn1;
+let $count_sessions=1;
+source include/wait_until_count_sessions.inc;
+
 drop user user1@localhost;
 
 set global server_audit_events='';
@@ -179,7 +192,6 @@ show status like 'server_audit_current_log';
 show variables like 'server_audit%';
 uninstall plugin server_audit;
 
-let $MYSQLD_DATADIR= `SELECT @@datadir`;
 # replace the timestamp and the hostname with constant values
 --replace_regex /[0-9]* [0-9][0-9]:[0-9][0-9]:[0-9][0-9]\,[^,]*\,/TIME,HOSTNAME,/ /\,[1-9][0-9]*\,/,1,/ /\,[1-9][0-9]*/,ID/
 cat_file $MYSQLD_DATADIR/server_audit.log;