Merge mysql.com:/opt/local/work/tmp_merge

into  mysql.com:/opt/local/work/mysql-5.1-merge


mysql-test/r/ps.result:
  Auto merged
mysql-test/t/ps.test:
  Auto merged
sql/mysql_priv.h:
  Auto merged
sql/mysqld.cc:
  Auto merged
sql/sql_class.cc:
  Auto merged
sql/sql_class.h:
  Auto merged
sql/sql_prepare.cc:
  Auto merged
sql/set_var.cc:
  Manual merge.
sql/set_var.h:
  Manual merge.
sql/share/errmsg.txt:
  Manual merge.

1 files changed, 32 insertions, 1 deletions

diff --git a/sql/mysqld.cc b/sql/mysqld.cc
index 541cc13aaea..73bd0d57eb3 100644
--- a/sql/mysqld.cc
+++ b/sql/mysqld.cc
@@ -500,6 +500,22 @@ ulong specialflag=0;
 ulong binlog_cache_use= 0, binlog_cache_disk_use= 0;
 ulong max_connections, max_connect_errors;
 uint  max_user_connections= 0;
+/*
+  Limit of the total number of prepared statements in the server.
+  Is necessary to protect the server against out-of-memory attacks.
+*/
+ulong max_prepared_stmt_count;
+/*
+  Current total number of prepared statements in the server. This number
+  is exact, and therefore may not be equal to the difference between
+  `com_stmt_prepare' and `com_stmt_close' (global status variables), as
+  the latter ones account for all registered attempts to prepare
+  a statement (including unsuccessful ones).  Prepared statements are
+  currently connection-local: if the same SQL query text is prepared in
+  two different connections, this counts as two distinct prepared
+  statements.
+*/
+ulong prepared_stmt_count=0;
 ulong thread_id=1L,current_pid;
 ulong slow_launch_threads = 0, sync_binlog_period;
 ulong expire_logs_days = 0;
@@ -577,6 +593,14 @@ pthread_mutex_t LOCK_mysql_create_db, LOCK_Acl, LOCK_open, LOCK_thread_count,
 		LOCK_crypt, LOCK_bytes_sent, LOCK_bytes_received,
 	        LOCK_global_system_variables,
 		LOCK_user_conn, LOCK_slave_list, LOCK_active_mi;
+/*
+  The below lock protects access to two global server variables:
+  max_prepared_stmt_count and prepared_stmt_count. These variables
+  set the limit and hold the current total number of prepared statements
+  in the server, respectively. As PREPARE/DEALLOCATE rate in a loaded
+  server may be fairly high, we need a dedicated lock.
+*/
+pthread_mutex_t LOCK_prepared_stmt_count;
 #ifdef HAVE_OPENSSL
 pthread_mutex_t LOCK_des_key_file;
 #endif
@@ -1288,6 +1312,7 @@ static void clean_up_mutexes()
   (void) pthread_mutex_destroy(&LOCK_global_system_variables);
   (void) pthread_mutex_destroy(&LOCK_global_read_lock);
   (void) pthread_mutex_destroy(&LOCK_uuid_generator);
+  (void) pthread_mutex_destroy(&LOCK_prepared_stmt_count);
   (void) pthread_cond_destroy(&COND_thread_count);
   (void) pthread_cond_destroy(&COND_refresh);
   (void) pthread_cond_destroy(&COND_thread_cache);
@@ -2810,6 +2835,7 @@ static int init_thread_environment()
   (void) pthread_mutex_init(&LOCK_active_mi, MY_MUTEX_INIT_FAST);
   (void) pthread_mutex_init(&LOCK_global_system_variables, MY_MUTEX_INIT_FAST);
   (void) pthread_mutex_init(&LOCK_global_read_lock, MY_MUTEX_INIT_FAST);
+  (void) pthread_mutex_init(&LOCK_prepared_stmt_count, MY_MUTEX_INIT_FAST);
   (void) pthread_mutex_init(&LOCK_uuid_generator, MY_MUTEX_INIT_FAST);
 #ifdef HAVE_OPENSSL
   (void) pthread_mutex_init(&LOCK_des_key_file,MY_MUTEX_INIT_FAST);
@@ -4634,7 +4660,8 @@ enum options_mysqld
   OPT_MAX_BINLOG_CACHE_SIZE, OPT_MAX_BINLOG_SIZE,
   OPT_MAX_CONNECTIONS, OPT_MAX_CONNECT_ERRORS,
   OPT_MAX_DELAYED_THREADS, OPT_MAX_HEP_TABLE_SIZE,
-  OPT_MAX_JOIN_SIZE, OPT_MAX_RELAY_LOG_SIZE, OPT_MAX_SORT_LENGTH, 
+  OPT_MAX_JOIN_SIZE, OPT_MAX_PREPARED_STMT_COUNT,
+  OPT_MAX_RELAY_LOG_SIZE, OPT_MAX_SORT_LENGTH,
   OPT_MAX_SEEKS_FOR_KEY, OPT_MAX_TMP_TABLES, OPT_MAX_USER_CONNECTIONS,
   OPT_MAX_LENGTH_FOR_SORT_DATA,
   OPT_MAX_WRITE_LOCK_COUNT, OPT_BULK_INSERT_BUFFER_SIZE,
@@ -5890,6 +5917,10 @@ The minimum value for this variable is 4096.",
     (gptr*) &global_system_variables.max_length_for_sort_data,
     (gptr*) &max_system_variables.max_length_for_sort_data, 0, GET_ULONG,
     REQUIRED_ARG, 1024, 4, 8192*1024L, 0, 1, 0},
+  {"max_prepared_stmt_count", OPT_MAX_PREPARED_STMT_COUNT,
+   "Maximum numbrer of prepared statements in the server.",
+   (gptr*) &max_prepared_stmt_count, (gptr*) &max_prepared_stmt_count,
+   0, GET_ULONG, REQUIRED_ARG, 16382, 0, 1*1024*1024, 0, 1, 0},
   {"max_relay_log_size", OPT_MAX_RELAY_LOG_SIZE,
    "If non-zero: relay log will be rotated automatically when the size exceeds this value; if zero (the default): when the size exceeds max_binlog_size. 0 excepted, the minimum value for this variable is 4096.",
    (gptr*) &max_relay_log_size, (gptr*) &max_relay_log_size, 0, GET_ULONG,