Ensure MySQL is only initialized once

Author: roavin

dbdimp.c

@@ -57,6 +57,21 @@ typedef struct sql_type_info_s
     int is_num;
 } sql_type_info_t;
 
+/*
+  Ensure we only call mysql_library_init once, since that is not threadsafe.
+  Not doing this before had lead to crashes in Apache MPM workers.
+*/ 
+pthread_once_t once_mysql_initialized = PTHREAD_ONCE_INIT;
+
+static void init_mysql_library(void)
+{
+  mysql_library_init(0, NULL, NULL);
+}
+
+static void ensure_mysql_initialized()
+{
+  pthread_once(&once_mysql_initialized, init_mysql_library);
+}
 
 /*
 
@@ -1206,7 +1221,7 @@ MYSQL *mysql_dr_connect(
 #else
     client_flag = CLIENT_FOUND_ROWS;
 #endif
-    mysql_library_init(0, NULL, NULL);
+    ensure_mysql_initialized();
     mysql_init(sock);
 
     if (imp_dbh)

dbdimp.h

@@ -22,7 +22,7 @@
 #include <mysql.h>  /* Comes with MySQL-devel */
 #include <mysqld_error.h>  /* Comes MySQL */
 #include <errmsg.h> /* Comes with MySQL-devel */
-
+#include <pthread.h>
 
 #define true 1
 #define false 0