MDEV-17845 Extreme high open file limit used

SHOW STATUS LIKE 'Open_files' was showing 18446744073709551615

my_file_opened used statistic_increment/statistic_decrement,
so one-off errors were normal and expected. But they confused
monitoring tools, so let's move my_file_opened to use atomics.

include/my_pthread.h

@@ -23,6 +23,8 @@
 #define ETIME ETIMEDOUT				/* For FreeBSD */
 #endif
 
+#include <my_atomic.h>
+
 #ifdef  __cplusplus
 #define EXTERNC extern "C"
 extern "C" {
@@ -803,6 +805,26 @@ extern uint thd_lib_detected;
 #define statistic_sub(V,C,L)     (V)-=(C)
 #endif /* SAFE_STATISTICS */
 
+static inline void thread_safe_increment32(int32 *value)
+{
+  (void) my_atomic_add32_explicit(value, 1, MY_MEMORY_ORDER_RELAXED);
+}
+
+static inline void thread_safe_decrement32(int32 *value)
+{
+  (void) my_atomic_add32_explicit(value, -1, MY_MEMORY_ORDER_RELAXED);
+}
+
+static inline void thread_safe_increment64(int64 *value)
+{
+  (void) my_atomic_add64_explicit(value, 1, MY_MEMORY_ORDER_RELAXED);
+}
+
+static inline void thread_safe_decrement64(int64 *value)
+{
+  (void) my_atomic_add64_explicit(value, -1, MY_MEMORY_ORDER_RELAXED);
+}
+
 /*
   No locking needed, the counter is owned by the thread
 */

include/my_sys.h

@@ -261,10 +261,11 @@ extern ulonglong my_collation_statistics_get_use_count(uint id);
 extern const char *my_collation_get_tailoring(uint id);
 
 /* statistics */
-extern ulong	my_file_opened,my_stream_opened, my_tmp_file_created;
+extern ulong    my_stream_opened, my_tmp_file_created;
 extern ulong    my_file_total_opened;
 extern ulong    my_sync_count;
 extern uint	mysys_usage_id;
+extern int32    my_file_opened;
 extern my_bool	my_init_done, my_thr_key_mysys_exists;
 extern my_bool  my_assert_on_error;
 extern myf      my_global_flags;        /* Set to MY_WME for more error messages */

mysys/my_fopen.c

@@ -223,7 +223,7 @@ FILE *my_fdopen(File Filedes, const char *name, int Flags, myf MyFlags)
     {
       if (my_file_info[Filedes].type != UNOPEN)
       {
-        statistic_decrement(my_file_opened, &THR_LOCK_open);		/* File is opened with my_open ! */
+        thread_safe_decrement32(&my_file_opened);       /* File is opened with my_open ! */
       }
       else
       {

mysys/my_open.c

@@ -105,7 +105,7 @@ int my_close(File fd, myf MyFlags)
   {
     my_free(name);
   }
-  statistic_decrement(my_file_opened, &THR_LOCK_open);
+  thread_safe_decrement32(&my_file_opened);
   DBUG_RETURN(err);
 } /* my_close */
 
@@ -133,13 +133,10 @@ File my_register_filename(File fd, const char *FileName, enum file_type
   DBUG_ENTER("my_register_filename");
   if ((int) fd >= MY_FILE_MIN)
   {
+    thread_safe_increment32(&my_file_opened);
     if ((uint) fd >= my_file_limit)
-    {
+      DBUG_RETURN(fd);
-      statistic_increment(my_file_opened,&THR_LOCK_open);
-      DBUG_RETURN(fd);				/* safeguard */
-    }
     my_file_info[fd].name = (char*) my_strdup(FileName, MyFlags);
-    statistic_increment(my_file_opened,&THR_LOCK_open);
     statistic_increment(my_file_total_opened,&THR_LOCK_open);
     my_file_info[fd].type = type_of_file;
     DBUG_PRINT("exit",("fd: %d",fd));

mysys/my_static.c

@@ -31,7 +31,7 @@ char *mysql_data_home= (char*) ".";
 const char      *my_progname= NULL, *my_progname_short= NULL;
 char		curr_dir[FN_REFLEN]= {0},
 		home_dir_buff[FN_REFLEN]= {0};
-ulong		my_stream_opened=0,my_file_opened=0, my_tmp_file_created=0;
+ulong		my_stream_opened=0,my_tmp_file_created=0;
 ulong           my_file_total_opened= 0;
 int		my_umask=0664, my_umask_dir=0777;
 
@@ -39,6 +39,7 @@ myf             my_global_flags= 0;
 my_bool         my_assert_on_error= 0;
 struct st_my_file_info my_file_info_default[MY_NFILE];
 uint   my_file_limit= MY_NFILE;
+int32           my_file_opened=0;
 struct st_my_file_info *my_file_info= my_file_info_default;
 
 	/* From mf_brkhant */

sql/mysqld.cc

@@ -8630,7 +8630,7 @@ SHOW_VAR status_vars[]= {
   {"Memory_used",              (char*) &show_memory_used, SHOW_SIMPLE_FUNC},
   {"Memory_used_initial",      (char*) &start_memory_used, SHOW_LONGLONG},
   {"Not_flushed_delayed_rows", (char*) &delayed_rows_in_use,    SHOW_LONG_NOFLUSH},
-  {"Open_files",               (char*) &my_file_opened,         SHOW_LONG_NOFLUSH},
+  {"Open_files",               (char*) &my_file_opened,         SHOW_SINT},
   {"Open_streams",             (char*) &my_stream_opened,       SHOW_LONG_NOFLUSH},
   {"Open_table_definitions",   (char*) &show_table_definitions, SHOW_SIMPLE_FUNC},
   {"Open_tables",              (char*) &show_open_tables,       SHOW_SIMPLE_FUNC},

sql/mysqld.h

@@ -790,26 +790,6 @@ inline void table_case_convert(char * name, uint length)
                                      name, length, name, length);
 }
 
-inline void thread_safe_increment32(int32 *value)
-{
-  (void) my_atomic_add32_explicit(value, 1, MY_MEMORY_ORDER_RELAXED);
-}
-
-inline void thread_safe_decrement32(int32 *value)
-{
-  (void) my_atomic_add32_explicit(value, -1, MY_MEMORY_ORDER_RELAXED);
-}
-
-inline void thread_safe_increment64(int64 *value)
-{
-  (void) my_atomic_add64_explicit(value, 1, MY_MEMORY_ORDER_RELAXED);
-}
-
-inline void thread_safe_decrement64(int64 *value)
-{
-  (void) my_atomic_add64_explicit(value, -1, MY_MEMORY_ORDER_RELAXED);
-}
-
 extern void set_server_version(char *buf, size_t size);
 
 #define current_thd _current_thd()

sql/sql_test.cc

@@ -596,13 +596,13 @@ update:     %10lu\n",
 	 tmp.ha_update_count);
   printf("\nTable status:\n\
 Opened tables: %10lu\n\
-Open tables:   %10lu\n\
+Open tables:   %10u\n\
-Open files:    %10lu\n\
+Open files:    %10u\n\
 Open streams:  %10lu\n",
 	 tmp.opened_tables,
-	 (ulong) tc_records(),
+	 tc_records(),
-	 (ulong) my_file_opened,
+	 my_file_opened,
-	 (ulong) my_stream_opened);
+	 my_stream_opened);
 
 #ifndef DONT_USE_THR_ALARM
   ALARM_INFO alarm_info;