new configuration: audit_json_file_bufsize . Controls the buffer size used when logging to a file. Value of 0 means default size, value of 1 means no buffering.

include/audit_handler.h

@@ -554,7 +554,7 @@ class Audit_file_handler: public Audit_io_handler
 public:
 
     Audit_file_handler() :
-        m_sync_period(0), m_log_file(NULL), m_sync_counter(0)
+        m_sync_period(0), m_log_file(NULL), m_sync_counter(0), m_bufsize(0)
     {
 		m_io_type = "file";
     }
@@ -571,6 +571,11 @@ public:
      */
     unsigned int m_sync_period;
     
+    /**
+     * The buf size used by the file stream. 0 = use default, negative or 1 = no buffering
+     */
+    long m_bufsize;
+    
     /**
      * Write function we pass to formatter
      */

src/audit_handler.cc

@@ -21,6 +21,7 @@
 #include "audit_handler.h"
 //for definition of sockaddr_un
 #include <sys/un.h>
+#include <stdio_ext.h>
 #include "static_assert.h"
 
 //utility macro to log also with a date as a prefix
@@ -198,7 +199,7 @@ int Audit_file_handler::open(const char * io_dest, bool log_errors)
 {
 	char format_name[FN_REFLEN];
     fn_format(format_name, io_dest, "", "", MY_UNPACK_FILENAME);
-    m_log_file = my_fopen(format_name, O_RDWR | O_APPEND, MYF(0));
+    m_log_file = my_fopen(format_name,  O_WRONLY | O_APPEND| O_CREAT, MYF(0));
 	if (!m_log_file)
     {
 		if(log_errors)
@@ -209,6 +210,31 @@ int Audit_file_handler::open(const char * io_dest, bool log_errors)
 		}
 		return -1;
 	}
+    ssize_t bufsize = BUFSIZ;
+    int res =0;
+    //0 -> use default, 1 or negative -> disabled
+    if(m_bufsize > 1) 
+    {
+        bufsize = m_bufsize;
+    }
+    if(1 == m_bufsize || m_bufsize < 0)
+    {
+        //disabled
+        res = setvbuf(m_log_file, NULL,  _IONBF, 0);
+    }
+    else
+    {   
+        res = setvbuf(m_log_file, NULL, _IOFBF, bufsize);        
+        
+    }    
+    if(res)
+    {
+        sql_print_error(
+					"%s unable to set bufzie [%zd (%ld)] for file %s: %s.",
+					AUDIT_LOG_PREFIX, bufsize, m_bufsize, m_io_dest, strerror(errno));
+    }
+    sql_print_information("%s bufsize for file [%s]: %zd. Value of json_file_bufsize: %ld.", AUDIT_LOG_PREFIX, m_io_dest, 
+        __fbufsize(m_log_file), m_bufsize);
 	return 0;
 }
 

src/audit_plugin.cc

@@ -1591,6 +1591,10 @@ static MYSQL_SYSVAR_STR(json_log_file, json_file_handler.m_io_dest,
         PLUGIN_VAR_RQCMDARG | PLUGIN_VAR_MEMALLOC,
         "AUDIT plugin json log file name",
         NULL, NULL, "mysql-audit.json");
+static MYSQL_SYSVAR_LONG(json_file_bufsize, json_file_handler.m_bufsize,
+        PLUGIN_VAR_RQCMDARG,
+        "AUDIT plugin json log file buffer size. Buffer size in bytes (lager size may improve performance). 0 = use default size, 1 = no buffering. If changed during runtime need to perform a flush for the new value to take affect.",
+        NULL, NULL, 0, 1, 262144, 0);
 
 static MYSQL_SYSVAR_UINT(json_file_sync, json_file_handler.m_sync_period,
         PLUGIN_VAR_RQCMDARG,
@@ -1713,6 +1717,7 @@ static struct st_mysql_sys_var* audit_system_variables[] =
 	MYSQL_SYSVAR(header_msg),
 	MYSQL_SYSVAR(force_record_logins),
 	MYSQL_SYSVAR(json_log_file),
+    MYSQL_SYSVAR(json_file_bufsize),
 	MYSQL_SYSVAR(json_file_sync),
 	MYSQL_SYSVAR(json_file_retry),
 	MYSQL_SYSVAR(json_socket_retry),