WL#1339 "Add per account max_user_connections limit (maximum number

of concurrent connections for the same account)"

Added support of account specific max_user_connections limit. Made all
user limits to be counted per account instead of the old behavior,
which was per user/host accounting. Added option which enables the old
behavior. Added testing of these to the test suite.

(After review version).


client/mysqltest.c:
  Extended mysqltest to be able to handle connect() statements for which
  error is expected.
  
  - Added replace_dynstr_append() utility function.
  - added connect_n_handle_errors() function which connects with server
    without retries and handles errors as if "connect" was usual
    statement.
  - do_connect(): added ability to handle connects which are expected
    to return an error.
  - run_query_normal(): Moved all expected-error-handling code to separate
    normal_handle_error()/normal_handle_no_error() functions to be able
    to reuse them in connect_n_handle_errors().
mysql-test/r/grant.result:
  Fixed test results since one more column to mysql.user was added.
mysql-test/r/system_mysql_db.result:
  Fixed test results since one more column to mysql.user was added.
scripts/mysql_create_system_tables.sh:
  Added max_user_connections column to mysql.user table for storing
  new maximal concurrent connections per account limit.
scripts/mysql_fix_privilege_tables.sql:
  Added max_user_connections column to mysql.user table for storing
  new maximal concurrent connections per account limit.
sql/lex.h:
  Added MAX_USER_CONNECTIONS symbol used for specifying
  maximum number of concurrent connections per account.
sql/mysql_priv.h:
  Added declaration of opt_old_style_user_limits variable which is defined
  in sql/mysqld.cc used in sql/sql_parse.cc.
sql/mysqld.cc:
  Added "old-style-user-limits" option which forces user limits to behave
  in old way i.e. to be counted per user/host pair instead of per account.
  Added comment describing mqh_used variable.
sql/set_var.cc:
  Added sys_var_max_user_conn class which implements support for the new 
  behavior of max_user_connections variable. Now the global instance of
  this variable holds default maximum number of concurrent connections per
  account (as it was before) and the session instance gives read-only
  access to account-specific version of this limit.
sql/set_var.h:
  Added sys_var_max_user_conn class which implements support for the new 
  behavior of max_user_connections variable. Now the global instance of
  this variable holds default maximum number of concurrent connections per
  account (as it was before) and the session instance gives read-only
  access to account-specific version of this limit.
sql/sql_acl.cc:
  Added support for account-specific MAX_USER_CONNECTIONS limit.
  Tweaked USER_RESOURCES and their handling for better clarity.
sql/sql_parse.cc:
  Added support for account-specific MAX_USER_CONNECTIONS (maximum number
  of concurrent connections per account) limit. Changed default behavior
  of all user limits to be per account instead of per user+host.
  '--old-style-user-limits' option was added to enable the old behavior.
  Made maximum number of connections per hour to be independant on the
  value of global max_user_connections variable.
sql/sql_yacc.yy:
  Added support of new MAX_USER_CONNECTIONS limit to grammar.
  Renamed USER_RESOURCES::connections member to conn_per_hour and bits
  member to specified_limits. Also enum is used instead of naked numbers
  when we are working with specified_limits.
sql/structs.h:
  USER_RESOURCES struct:
   - Added user_conn member to store the maximum number of concurrent 
     connections for an account. Renamed connections member to 
     conn_per_hour for less ambiguity.
   - Renamed member 'bits' to 'specified_limits' for the sake of clarity.
     The member was used as a flag indicating which limits were mentioned
     in GRANT clause.
   - Added comments.
  USER_CONN struct:
   - Removed unused user_len member.
   - Added comments.

1 files changed, 89 insertions, 0 deletions

diff --git a/mysql-test/r/user_limits.result b/mysql-test/r/user_limits.result
new file mode 100644
index 00000000000..d15f99337b7
--- /dev/null
+++ b/mysql-test/r/user_limits.result
@@ -0,0 +1,89 @@
+drop table if exists t1;
+create table t1 (i int);
+delete from mysql.user where user like 'mysqltest\_%';
+delete from mysql.db where user like 'mysqltest\_%';
+delete from mysql.tables_priv where user like 'mysqltest\_%';
+delete from mysql.columns_priv where user like 'mysqltest\_%';
+flush privileges;
+grant usage on *.* to mysqltest_1@localhost with max_queries_per_hour 2;
+select * from t1;
+i
+select * from t1;
+i
+select * from t1;
+ERROR 42000: User 'mysqltest_1' has exceeded the 'max_questions' resource (current value: 2)
+select * from t1;
+ERROR 42000: User 'mysqltest_1' has exceeded the 'max_questions' resource (current value: 2)
+drop user mysqltest_1@localhost;
+grant usage on *.* to mysqltest_1@localhost with max_updates_per_hour 2;
+select * from t1;
+i
+select * from t1;
+i
+select * from t1;
+i
+delete from t1;
+delete from t1;
+delete from t1;
+ERROR 42000: User 'mysqltest_1' has exceeded the 'max_updates' resource (current value: 2)
+select * from t1;
+i
+delete from t1;
+ERROR 42000: User 'mysqltest_1' has exceeded the 'max_updates' resource (current value: 2)
+select * from t1;
+i
+drop user mysqltest_1@localhost;
+grant usage on *.* to mysqltest_1@localhost with max_connections_per_hour 2;
+select * from t1;
+i
+select * from t1;
+i
+connect(localhost,mysqltest_1,,test,MYSQL_PORT,MYSQL_SOCK);
+ERROR 42000: User 'mysqltest_1' has exceeded the 'max_connections' resource (current value: 2)
+select * from t1;
+i
+connect(localhost,mysqltest_1,,test,9306,/home/dlenev/src/mysql-5.0-1339/mysql-test/var/tmp/master.sock);
+ERROR 42000: User 'mysqltest_1' has exceeded the 'max_connections' resource (current value: 2)
+drop user mysqltest_1@localhost;
+flush privileges;
+grant usage on *.* to mysqltest_1@localhost with max_user_connections 2;
+select * from t1;
+i
+select * from t1;
+i
+connect(localhost,mysqltest_1,,test,MYSQL_PORT,MYSQL_SOCK);
+ERROR 42000: User 'mysqltest_1' has exceeded the 'max_user_connections' resource (current value: 2)
+select * from t1;
+i
+grant usage on *.* to mysqltest_1@localhost with max_user_connections 3;
+select * from t1;
+i
+connect(localhost,mysqltest_1,,test,MYSQL_PORT,MYSQL_SOCK);
+ERROR 42000: User 'mysqltest_1' has exceeded the 'max_user_connections' resource (current value: 3)
+drop user mysqltest_1@localhost;
+select @@session.max_user_connections, @@global.max_user_connections;
+@@session.max_user_connections	@@global.max_user_connections
+0	0
+set session max_user_connections= 2;
+ERROR HY000: Variable 'max_user_connections' is a GLOBAL variable and should be set with SET GLOBAL
+set global max_user_connections= 2;
+select @@session.max_user_connections, @@global.max_user_connections;
+@@session.max_user_connections	@@global.max_user_connections
+2	2
+grant usage on *.* to mysqltest_1@localhost;
+select @@session.max_user_connections, @@global.max_user_connections;
+@@session.max_user_connections	@@global.max_user_connections
+2	2
+select * from t1;
+i
+connect(localhost,mysqltest_1,,test,MYSQL_PORT,MYSQL_SOCK);
+ERROR 42000: User mysqltest_1 has already more than 'max_user_connections' active connections
+grant usage on *.* to mysqltest_1@localhost with max_user_connections 3;
+select @@session.max_user_connections, @@global.max_user_connections;
+@@session.max_user_connections	@@global.max_user_connections
+3	2
+connect(localhost,mysqltest_1,,test,MYSQL_PORT,MYSQL_SOCK);
+ERROR 42000: User 'mysqltest_1' has exceeded the 'max_user_connections' resource (current value: 3)
+set global max_user_connections= 0;
+drop user mysqltest_1@localhost;
+drop table t1;