Add global variable max_nonsuper_connections

Summary:
The new global variable `max_nonsuper_connections` will enforce the limit for
the sum of all non-admin connections. This will be useful to limit regular user
connections while still allow super users to connect to server.
Closes #389

Reviewed By: anca-agape

Differential Revision: D4123732

Pulled By: tianx

fbshipit-source-id: 7ffb140

mysql-test/r/max_nonsuper_connections.result

@@ -0,0 +1,81 @@
+create user test_user@localhost;
+grant all on test to test_user@localhost;
+create user super_user@localhost;
+grant all on *.* to super_user@localhost with grant option;
+SET @start_value = @@global.max_nonsuper_connections;
+SET @@global.max_nonsuper_connections = 10;
+SELECT @@global.max_nonsuper_connections;
+@@global.max_nonsuper_connections
+10
+connection default;
+connect  con$i, localhost, test_user,,test;
+connect  con$i, localhost, test_user,,test;
+connect  con$i, localhost, test_user,,test;
+connect  con$i, localhost, test_user,,test;
+connect  con$i, localhost, test_user,,test;
+connect  con$i, localhost, test_user,,test;
+connect  con$i, localhost, test_user,,test;
+connect  con$i, localhost, test_user,,test;
+connect  con$i, localhost, test_user,,test;
+connect  con$i, localhost, test_user,,test;
+ERROR 08004: Too many connections
+connect  con_root, localhost, root,,test;
+# connection con_root
+connection con_root;
+SELECT @@global.max_nonsuper_connections;
+@@global.max_nonsuper_connections
+10
+disconnect con_root;
+connection default;
+connect  con_super, localhost, super_user,,test;
+connection con_super;
+SELECT @@global.max_nonsuper_connections;
+@@global.max_nonsuper_connections
+10
+mysqltest: At line 1: change user failed: Too many connections
+disconnect con_super;
+connection con10;
+connect  con11, localhost, test_user,,test;
+disconnect con11;
+connection con10;
+ERROR 08004: Too many connections
+connection default;
+disconnect con10;
+disconnect con9;
+disconnect con8;
+disconnect con7;
+disconnect con6;
+disconnect con5;
+disconnect con4;
+disconnect con3;
+disconnect con2;
+disconnect con1;
+connection default;
+connect  con$i, localhost, test_user,,test;
+connect  con$i, localhost, test_user,,test;
+connect  con$i, localhost, test_user,,test;
+connect  con$i, localhost, test_user,,test;
+connect  con$i, localhost, test_user,,test;
+connect  con$i, localhost, test_user,,test;
+connect  con$i, localhost, test_user,,test;
+connect  con$i, localhost, test_user,,test;
+connect  con$i, localhost, test_user,,test;
+connect  con$i, localhost, test_user,,test;
+ERROR 08004: Too many connections
+connection default;
+SET @@global.max_nonsuper_connections = @start_value;
+SELECT @@global.max_nonsuper_connections;
+@@global.max_nonsuper_connections
+0
+drop user test_user@localhost;
+drop user super_user@localhost;
+disconnect con10;
+disconnect con9;
+disconnect con8;
+disconnect con7;
+disconnect con6;
+disconnect con5;
+disconnect con4;
+disconnect con3;
+disconnect con2;
+disconnect con1;

mysql-test/r/mysqld--help-notwin-profiling.result

@@ -537,6 +537,9 @@ The following options may be given as the first argument:
  max_join_size records return an error
  --max-length-for-sort-data=# 
  Max number of bytes in sorted records
+ --max-nonsuper-connections=# 
+ The maximum number of total active connections for
+ non-super user (0 = no limit)
  --max-prepared-stmt-count=# 
  Maximum number of prepared statements in the server
  --max-relay-log-size=# 
@@ -1745,6 +1748,7 @@ max-error-count 64
 max-heap-table-size 16777216
 max-join-size 18446744073709551615
 max-length-for-sort-data 1024
+max-nonsuper-connections 0
 max-prepared-stmt-count 16382
 max-relay-log-size 0
 max-running-queries 0

mysql-test/r/mysqld--help-notwin.result

@@ -537,6 +537,9 @@ The following options may be given as the first argument:
  max_join_size records return an error
  --max-length-for-sort-data=# 
  Max number of bytes in sorted records
+ --max-nonsuper-connections=# 
+ The maximum number of total active connections for
+ non-super user (0 = no limit)
  --max-prepared-stmt-count=# 
  Maximum number of prepared statements in the server
  --max-relay-log-size=# 
@@ -1743,6 +1746,7 @@ max-error-count 64
 max-heap-table-size 16777216
 max-join-size 18446744073709551615
 max-length-for-sort-data 1024
+max-nonsuper-connections 0
 max-prepared-stmt-count 16382
 max-relay-log-size 0
 max-running-queries 0

mysql-test/suite/sys_vars/r/max_nonsuper_connections_basic.result

@@ -0,0 +1,102 @@
+SET @start_value = @@global.max_nonsuper_connections;
+SELECT @start_value;
+@start_value
+0
+SET @@global.max_nonsuper_connections = DEFAULT;
+SELECT @@global.max_nonsuper_connections;
+@@global.max_nonsuper_connections
+0
+SET @@global.max_nonsuper_connections = 100000;
+SELECT @@global.max_nonsuper_connections;
+@@global.max_nonsuper_connections
+100000
+SET @@global.max_nonsuper_connections = 99999;
+SELECT @@global.max_nonsuper_connections;
+@@global.max_nonsuper_connections
+99999
+SET @@global.max_nonsuper_connections = 65536;
+SELECT @@global.max_nonsuper_connections;
+@@global.max_nonsuper_connections
+65536
+SET @@global.max_nonsuper_connections = 1;
+SELECT @@global.max_nonsuper_connections;
+@@global.max_nonsuper_connections
+1
+SET @@global.max_nonsuper_connections = 2;
+SELECT @@global.max_nonsuper_connections;
+@@global.max_nonsuper_connections
+2
+SET @@global.max_nonsuper_connections = TRUE;
+SELECT @@global.max_nonsuper_connections;
+@@global.max_nonsuper_connections
+1
+SET @@global.max_nonsuper_connections = FALSE;
+SELECT @@global.max_nonsuper_connections;
+@@global.max_nonsuper_connections
+0
+SET @@global.max_nonsuper_connections = -1;
+Warnings:
+Warning	1292	Truncated incorrect max_nonsuper_connections value: '-1'
+SELECT @@global.max_nonsuper_connections;
+@@global.max_nonsuper_connections
+0
+SET @@global.max_nonsuper_connections = 100000000000;
+Warnings:
+Warning	1292	Truncated incorrect max_nonsuper_connections value: '100000000000'
+SELECT @@global.max_nonsuper_connections;
+@@global.max_nonsuper_connections
+4294967295
+SET @@global.max_nonsuper_connections = 10000.01;
+ERROR 42000: Incorrect argument type to variable 'max_nonsuper_connections'
+SELECT @@global.max_nonsuper_connections;
+@@global.max_nonsuper_connections
+4294967295
+SET @@global.max_nonsuper_connections = -1024;
+Warnings:
+Warning	1292	Truncated incorrect max_nonsuper_connections value: '-1024'
+SELECT @@global.max_nonsuper_connections;
+@@global.max_nonsuper_connections
+0
+SET @@global.max_nonsuper_connections = ON;
+ERROR 42000: Incorrect argument type to variable 'max_nonsuper_connections'
+SELECT @@global.max_nonsuper_connections;
+@@global.max_nonsuper_connections
+0
+SET @@global.max_nonsuper_connections = 'test';
+ERROR 42000: Incorrect argument type to variable 'max_nonsuper_connections'
+SELECT @@global.max_nonsuper_connections;
+@@global.max_nonsuper_connections
+0
+SET @@session.max_nonsuper_connections = 4096;
+ERROR HY000: Variable 'max_nonsuper_connections' is a GLOBAL variable and should be set with SET GLOBAL
+SELECT @@session.max_nonsuper_connections;
+ERROR HY000: Variable 'max_nonsuper_connections' is a GLOBAL variable
+SET max_nonsuper_connections = 6000;
+ERROR HY000: Variable 'max_nonsuper_connections' is a GLOBAL variable and should be set with SET GLOBAL
+SELECT @@max_nonsuper_connections;
+@@max_nonsuper_connections
+0
+SET local.max_nonsuper_connections = 7000;
+ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'max_nonsuper_connections = 7000' at line 1
+SELECT local.max_nonsuper_connections;
+ERROR 42S02: Unknown table 'local' in field list
+SET global.max_nonsuper_connections = 8000;
+ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'max_nonsuper_connections = 8000' at line 1
+SELECT global.max_nonsuper_connections;
+ERROR 42S02: Unknown table 'global' in field list
+SELECT max_nonsuper_connections = @@session.max_nonsuper_connections;
+ERROR 42S22: Unknown column 'max_nonsuper_connections' in 'field list'
+SELECT @@global.max_nonsuper_connections = VARIABLE_VALUE
+FROM INFORMATION_SCHEMA.GLOBAL_VARIABLES
+WHERE VARIABLE_NAME='max_nonsuper_connections';
+@@global.max_nonsuper_connections = VARIABLE_VALUE
+1
+SELECT @@max_nonsuper_connections = VARIABLE_VALUE
+FROM INFORMATION_SCHEMA.SESSION_VARIABLES
+WHERE VARIABLE_NAME='max_nonsuper_connections';
+@@max_nonsuper_connections = VARIABLE_VALUE
+1
+SET @@global.max_nonsuper_connections = @start_value;
+SELECT @@global.max_nonsuper_connections;
+@@global.max_nonsuper_connections
+0

mysql-test/suite/sys_vars/t/max_nonsuper_connections_basic.test

@@ -0,0 +1,95 @@
+--source include/load_sysvars.inc
+
+#
+# save original value
+#
+SET @start_value = @@global.max_nonsuper_connections;
+SELECT @start_value;
+
+
+#
+# set default value
+#
+SET @@global.max_nonsuper_connections = DEFAULT;
+SELECT @@global.max_nonsuper_connections;
+
+
+#
+# set various values
+#
+SET @@global.max_nonsuper_connections = 100000;
+SELECT @@global.max_nonsuper_connections;
+SET @@global.max_nonsuper_connections = 99999;
+SELECT @@global.max_nonsuper_connections;
+SET @@global.max_nonsuper_connections = 65536;
+SELECT @@global.max_nonsuper_connections;
+SET @@global.max_nonsuper_connections = 1;
+SELECT @@global.max_nonsuper_connections;
+SET @@global.max_nonsuper_connections = 2;
+SELECT @@global.max_nonsuper_connections;
+SET @@global.max_nonsuper_connections = TRUE;
+SELECT @@global.max_nonsuper_connections;
+SET @@global.max_nonsuper_connections = FALSE;
+SELECT @@global.max_nonsuper_connections;
+
+
+#
+# set invalid values
+#
+# Value truncated
+SET @@global.max_nonsuper_connections = -1;
+SELECT @@global.max_nonsuper_connections;
+# Value truncated
+SET @@global.max_nonsuper_connections = 100000000000;
+SELECT @@global.max_nonsuper_connections;
+--Error ER_WRONG_TYPE_FOR_VAR
+SET @@global.max_nonsuper_connections = 10000.01;
+SELECT @@global.max_nonsuper_connections;
+# Value truncated
+SET @@global.max_nonsuper_connections = -1024;
+SELECT @@global.max_nonsuper_connections;
+
+--Error ER_WRONG_TYPE_FOR_VAR
+SET @@global.max_nonsuper_connections = ON;
+SELECT @@global.max_nonsuper_connections;
+--Error ER_WRONG_TYPE_FOR_VAR
+SET @@global.max_nonsuper_connections = 'test';
+SELECT @@global.max_nonsuper_connections;
+
+--Error ER_GLOBAL_VARIABLE
+SET @@session.max_nonsuper_connections = 4096;
+--Error ER_INCORRECT_GLOBAL_LOCAL_VAR
+SELECT @@session.max_nonsuper_connections;
+
+--Error ER_GLOBAL_VARIABLE
+SET max_nonsuper_connections = 6000;
+SELECT @@max_nonsuper_connections;
+--Error ER_PARSE_ERROR
+SET local.max_nonsuper_connections = 7000;
+--Error ER_UNKNOWN_TABLE
+SELECT local.max_nonsuper_connections;
+--Error ER_PARSE_ERROR
+SET global.max_nonsuper_connections = 8000;
+--Error ER_UNKNOWN_TABLE
+SELECT global.max_nonsuper_connections;
+--Error ER_BAD_FIELD_ERROR
+SELECT max_nonsuper_connections = @@session.max_nonsuper_connections;
+
+
+#
+# Check if the value in GLOBAL & SESSION Tables matches values in variable
+#
+SELECT @@global.max_nonsuper_connections = VARIABLE_VALUE
+FROM INFORMATION_SCHEMA.GLOBAL_VARIABLES
+WHERE VARIABLE_NAME='max_nonsuper_connections';
+
+SELECT @@max_nonsuper_connections = VARIABLE_VALUE
+FROM INFORMATION_SCHEMA.SESSION_VARIABLES
+WHERE VARIABLE_NAME='max_nonsuper_connections';
+
+
+#
+# restore
+#
+SET @@global.max_nonsuper_connections = @start_value;
+SELECT @@global.max_nonsuper_connections;