Bug #50296 Slave reconnects earlier than the prescribed slave_net_timeout value

There was auto-reconnecting by slave earlier than a prescribed by slave_net_timeout value.
The issue happened on 64bit solaris that spotted rather incorrect casting of 
the ulong slave_net_timeout into the uint of mysql.options.read_timeout.

Notice, that there is no reason for slave_net_timeout to be of type of ulong.
Since it's primarily passed as arg to mysql_options the type can be made
as uint to avoid all conversion hassles.
That's what the fixes are made.
A "side" effect of the patch is a new value for the max of slave_net_timeout
to be the max of the unsigned int type (therefore to vary across platforms).

Note, a regression test can't be made to run reliably without making it to last over some 
20 secs. That's why it is placed in suite/large_tests.

mysql-test/suite/large_tests/r/rpl_slave_net_timeout.result

+stop slave;
+drop table if exists t1,t2,t3,t4,t5,t6,t7,t8,t9;
+reset master;
+reset slave;
+drop table if exists t1,t2,t3,t4,t5,t6,t7,t8,t9;
+start slave;
+set @save_general_log = @@global.general_log;
+set @save_log_output = @@global.log_output;
+set @save_slave_net_timeout = @@global.slave_net_timeout;
+set @@global.general_log = ON;
+set @@global.log_output = 'table,file';
+include/stop_slave.inc
+set @@global.slave_net_timeout = @@global.net_read_timeout * 2;
+change master to master_host = '127.0.0.1',master_port = 13020,
+master_user = 'root', master_heartbeat_period = 0;
+include/start_slave.inc
+include/stop_slave.inc
+select event_time from (select event_time from mysql.general_log as t_1 where command_type like 'Connect' order by event_time desc limit 2) as t_2 order by event_time desc limit 1 into @ts_last;
+select event_time from (select event_time from mysql.general_log as t_1 where command_type like 'Connect' order by event_time desc limit 2) as t_2 order by event_time asc limit 1 into @ts_prev;
+select @result as 'Must be 1';
+Must be 1
+1
+set @@global.general_log = @save_general_log;
+set @@global.log_output = @save_log_output;
+set @@global.slave_net_timeout = @save_slave_net_timeout;

mysql-test/suite/large_tests/t/rpl_slave_net_timeout-slave.opt

+--net_read_timeout=5

mysql-test/suite/large_tests/t/rpl_slave_net_timeout.test

+#
+#  Testing reconnecting by slave as specified by `slave_net_timeout'
+#
+#  Bug #50296 Slave reconnects earlier than the prescribed slave_net_timeout value
+#
+--source include/have_csv.inc
+--source include/master-slave.inc
+
+
+# save global env
+connection master;
+set @save_general_log = @@global.general_log;
+set @save_log_output = @@global.log_output;
+
+connection slave;
+set @save_slave_net_timeout = @@global.slave_net_timeout;
+
+connection master;
+set @@global.general_log = ON;
+set @@global.log_output = 'table,file';
+
+connection slave;
+--source include/stop_slave.inc
+--disable_warnings
+set @@global.slave_net_timeout = @@global.net_read_timeout * 2;
+--enable_warnings
+let $idle_time=`select @@global.slave_net_timeout * 2`;
+
+#
+# if heartbeat is disabled then reconnecting to the idle master
+# should happen with `slave_net_timeout' period.
+# Since it's the real time that is measured, `slave_net_timeout'
+# merely guarantees that reconnecting can *not* happen earlier of a value specified.
+# That is there can't an exact estimate for how many time it will happen.
+#
+# The following lines verify that having idle master 
+# for more than 2 * slave_net_timeout seconds and 
+# slave.net_read_timeout < slave_net_timeout
+# won't cause reconnecting by the slave within at least 
+# slave_net_timeout interval.
+
+eval change master to master_host = '127.0.0.1',master_port = $MASTER_MYPORT,
+master_user = 'root', master_heartbeat_period = 0;
+
+let $slave_net_timeout = `select @@global.slave_net_timeout`;
+
+--source include/start_slave.inc
+
+--disable_query_log
+--disable_result_log
+eval select 'master is idle for ', sleep($idle_time);
+--enable_result_log
+--enable_query_log
+
+--source include/stop_slave.inc
+
+# querying general-log
+
+connection master;
+
+# In particular the last reconnection timestamp must be greater or equal to
+# the previous one + slave_net_timeout
+
+select event_time from (select event_time from mysql.general_log as t_1 where command_type like 'Connect' order by event_time desc limit 2) as t_2 order by event_time desc limit 1 into @ts_last;
+select event_time from (select event_time from mysql.general_log as t_1 where command_type like 'Connect' order by event_time desc limit 2) as t_2 order by event_time asc limit 1 into @ts_prev;
+
+--disable_query_log
+eval select time_to_sec(@ts_last) - $slave_net_timeout >= time_to_sec(@ts_prev) into @result;
+--enable_query_log
+
+select @result as 'Must be 1';
+
+# cleanup 
+
+# restore global env
+connection master;
+set @@global.general_log = @save_general_log;
+set @@global.log_output = @save_log_output;
+connection slave;
+set @@global.slave_net_timeout = @save_slave_net_timeout;
+

sql/mysql_priv.h

@@ -1970,7 +1970,8 @@ extern ulong slow_launch_threads, slow_launch_time;
 extern ulong table_cache_size, table_def_size;
 extern MYSQL_PLUGIN_IMPORT ulong max_connections;
 extern ulong max_connect_errors, connect_timeout;
-extern ulong slave_net_timeout, slave_trans_retries;
+extern ulong slave_trans_retries;
+extern uint  slave_net_timeout;
 extern ulong what_to_log,flush_time;
 extern ulong query_buff_size;
 extern ulong max_prepared_stmt_count, prepared_stmt_count;

sql/mysqld.cc

@@ -453,7 +453,8 @@ ulong table_cache_size, table_def_size;
 ulong what_to_log;
 ulong query_buff_size, slow_launch_time, slave_open_temp_tables;
 ulong open_files_limit, max_binlog_size, max_relay_log_size;
-ulong slave_net_timeout, slave_trans_retries;
+ulong slave_trans_retries;
+uint  slave_net_timeout;
 uint slave_exec_mode_options;
 ulonglong slave_type_conversions_options;
 ulong thread_cache_size=0, thread_pool_size= 0;

sql/sys_vars.cc

@@ -2811,7 +2811,7 @@ static Sys_var_ulong Sys_slave_net_timeout(
        "slave_net_timeout", "Number of seconds to wait for more data "
        "from a master/slave connection before aborting the read",
        GLOBAL_VAR(slave_net_timeout), CMD_LINE(REQUIRED_ARG),
-       VALID_RANGE(1, LONG_TIMEOUT), DEFAULT(SLAVE_NET_TIMEOUT), BLOCK_SIZE(1),
+       VALID_RANGE(1, UINT_MAX), DEFAULT(SLAVE_NET_TIMEOUT), BLOCK_SIZE(1),
        NO_MUTEX_GUARD, NOT_IN_BINLOG, ON_CHECK(0),
        ON_UPDATE(fix_slave_net_timeout));