BUG#11753923-SQL THREAD CRASHES ON DISK FULL

Problem:If Disk becomes full while writing into the binlog,
then the server instance hangs till someone frees the space.
After user frees up the disk space, mysql server crashes
with an assert (m_status != DA_EMPTY)

Analysis: wait_for_free_space is being called in an
infinite loop i.e., server instance will hang until
someone frees up the space. So there is no need to
set status bit in diagnostic area.

Fix: Replace my_error/my_printf_error with
sql_print_warning() which prints the warning in error log.

Author: Venkatesh Duggirala

include/my_sys.h

@@ -234,6 +234,7 @@ extern char *home_dir;			/* Home directory for user */
 extern const char *my_progname;		/* program-name (printed in errors) */
 extern char NEAR curr_dir[];		/* Current directory for user */
 extern int (*error_handler_hook)(uint my_err, const char *str,myf MyFlags);
+extern void(*sql_print_warning_hook)(const char *format,...);
 extern int (*fatal_error_handler_hook)(uint my_err, const char *str,
 				       myf MyFlags);
 extern uint my_file_limit;
@@ -675,6 +676,7 @@ extern int my_error _VARARGS((int nr,myf MyFlags, ...));
 extern int my_printf_error _VARARGS((uint my_err, const char *format,
 				     myf MyFlags, ...))
 				    ATTRIBUTE_FORMAT(printf, 2, 4);
+extern void my_printf_warning _VARARGS((const char * format, ...));
 extern int my_error_register(const char **errmsgs, int first, int last);
 extern const char **my_error_unregister(int first, int last);
 extern int my_message(uint my_err, const char *str,myf MyFlags);

mysys/errors.c

@@ -101,16 +101,28 @@ void init_glob_errs()
 }
 #endif
 
+/*
+ We cannot call my_error/my_printf_error here in this function.
+  Those functions will set status variable in diagnostic area
+  and there is no provision to reset them back.
+  Here we are waiting for free space and will wait forever till
+  space is created. So just giving warning in the error file
+  should be enough.
+*/
 void wait_for_free_space(const char *filename, int errors)
 {
-  if (errors == 0)
-    my_error(EE_DISK_FULL,MYF(ME_BELL | ME_NOREFRESH),
-             filename,my_errno,MY_WAIT_FOR_USER_TO_FIX_PANIC);
   if (!(errors % MY_WAIT_GIVE_USER_A_MESSAGE))
-    my_printf_error(EE_DISK_FULL,
-                    "Retry in %d secs. Message reprinted in %d secs",
-                    MYF(ME_BELL | ME_NOREFRESH),
+  {
+    my_printf_warning(EE(EE_DISK_FULL),
+             filename,my_errno,MY_WAIT_FOR_USER_TO_FIX_PANIC);
+    my_printf_warning("Retry in %d secs. Message reprinted in %d secs",
                     MY_WAIT_FOR_USER_TO_FIX_PANIC,
                     MY_WAIT_GIVE_USER_A_MESSAGE * MY_WAIT_FOR_USER_TO_FIX_PANIC );
+  }
+  DBUG_EXECUTE_IF("simulate_file_write_error_once",
+                 {
+                   VOID(sleep(1));
+                   return;
+                 });
   VOID(sleep(MY_WAIT_FOR_USER_TO_FIX_PANIC));
 }

mysys/my_error.c

@@ -128,6 +128,28 @@ int my_printf_error(uint error, const char *format, myf MyFlags, ...)
   DBUG_RETURN((*error_handler_hook)(error, ebuff, MyFlags));
 }
 
+/*
+  Warning as printf
+
+  SYNOPSIS
+    my_printf_warning()
+      format>   Format string
+      ...>      variable list
+*/
+void(*sql_print_warning_hook)(const char *format,...);
+void my_printf_warning(const char *format, ...)
+{
+  va_list args;
+  char wbuff[ERRMSGSIZE];
+  DBUG_ENTER("my_printf_warning");
+  DBUG_PRINT("my", ("Format: %s", format));
+  va_start(args,format);
+  (void) my_vsnprintf (wbuff, sizeof(wbuff), format, args);
+  va_end(args);
+  (*sql_print_warning_hook)(wbuff);
+  DBUG_VOID_RETURN;
+}
+
 /*
   Give message using error_handler_hook
 

mysys/my_write.c

@@ -36,6 +36,8 @@ size_t my_write(int Filedes, const uchar *Buffer, size_t Count, myf MyFlags)
   if (unlikely(!Count))
     DBUG_RETURN(0);
 
+  DBUG_EXECUTE_IF ("simulate_file_write_error_once",
+                   { DBUG_SET("+d,simulate_file_write_error");});
   for (;;)
   {
     writenbytes= write(Filedes, Buffer, Count);
@@ -69,6 +71,8 @@ size_t my_write(int Filedes, const uchar *Buffer, size_t Count, myf MyFlags)
     {
       wait_for_free_space(my_filename(Filedes), errors);
       errors++;
+      DBUG_EXECUTE_IF("simulate_file_write_error_once",
+                      { DBUG_SET("-d,simulate_file_write_error");});
       continue;
     }
 

sql/mysqld.cc

@@ -4375,6 +4375,7 @@ we force server id to 2, but this MySQL server will not act as a slave.");
     After this we can't quit by a simple unireg_abort
   */
   error_handler_hook= my_message_sql;
+  sql_print_warning_hook = sql_print_warning;
   start_signal_handler();				// Creates pidfile
 
   if (mysql_rm_tmp_tables() || acl_init(opt_noacl) ||