MDEV-15635 mysys: THR_LOCK_open reduce usage

Change the following to statistic counters:
* my_file_opened
* my_file_total_opened
* my_stream_opened
* my_tmp_file_created

There is one non-statistics use of my_file_opened/my_stream_opened
in my_end which prints a warning if we shutdown and its still open.
It seems excessive to hold locks to prevent this warning.

A file descriptor is already a unique element per process - in Windows,
protection occurs at fd allocation using THR_LOCK_open in my_win_{,f}open
and in other OSes, a unique fd to file map exists at the OS level.
So accesses to my_file_info[fd] don't need to be protected by the
THR_LOCK_open.

my_close/my_fclose where restructured to clear out the my_file_info
before the close/my_win_close/my_win_fclose. After these calls another
thread could gain the same file descriptor. So for Windows this
the file_info elements available to the my_win_{,f}_open are released
during the invalidate_fd call within my_win_close. No locking is needed
as the my_win_{,f}open is searching for a invalidate entry which is
determined by a single value change.

my_fclose also changed for non-Windows to retry closing if EINTR was
returned, same as my_close.

Closes #657

1 files changed, 21 insertions, 17 deletions

diff --git a/mysys/my_fopen.c b/mysys/my_fopen.c
index 213eac82040..59baeaec744 100644
--- a/mysys/my_fopen.c
+++ b/mysys/my_fopen.c
@@ -61,15 +61,13 @@ FILE *my_fopen(const char *filename, int flags, myf MyFlags)
     int filedesc= my_fileno(fd);
     if ((uint)filedesc >= my_file_limit)
     {
-      thread_safe_increment(my_stream_opened,&THR_LOCK_open);
+      statistic_increment(my_stream_opened,&THR_LOCK_open);
       DBUG_RETURN(fd);				/* safeguard */
     }
-    mysql_mutex_lock(&THR_LOCK_open);
     my_file_info[filedesc].name= (char*) my_strdup(filename,MyFlags);
-    my_stream_opened++;
-    my_file_total_opened++;
+    statistic_increment(my_stream_opened, &THR_LOCK_open);
+    statistic_increment(my_file_total_opened, &THR_LOCK_open);
     my_file_info[filedesc].type= STREAM_BY_FOPEN;
-    mysql_mutex_unlock(&THR_LOCK_open);
     DBUG_PRINT("exit",("stream: %p", fd));
     DBUG_RETURN(fd);
   }
@@ -161,13 +159,22 @@ FILE *my_freopen(const char *path, const char *mode, FILE *stream)
 int my_fclose(FILE *fd, myf MyFlags)
 {
   int err,file;
+  char *name= NULL;
   DBUG_ENTER("my_fclose");
   DBUG_PRINT("my",("stream: %p  MyFlags: %lu", fd, MyFlags));
 
-  mysql_mutex_lock(&THR_LOCK_open);
   file= my_fileno(fd);
+  if ((uint) file < my_file_limit && my_file_info[file].type != UNOPEN)
+  {
+    name= my_file_info[file].name;
+    my_file_info[file].name= NULL;
+    my_file_info[file].type= UNOPEN;
+  }
 #ifndef _WIN32
-  err= fclose(fd);
+  do
+  {
+    err= fclose(fd);
+  } while (err == -1 && errno == EINTR);
 #else
   err= my_win_fclose(fd);
 #endif
@@ -176,16 +183,15 @@ int my_fclose(FILE *fd, myf MyFlags)
     my_errno=errno;
     if (MyFlags & (MY_FAE | MY_WME))
       my_error(EE_BADCLOSE, MYF(ME_BELL+ME_WAITTANG),
-	       my_filename(file),errno);
+	       name,errno);
   }
   else
-    my_stream_opened--;
-  if ((uint) file < my_file_limit && my_file_info[file].type != UNOPEN)
+    statistic_decrement(my_stream_opened, &THR_LOCK_open);
+
+  if (name)
   {
-    my_file_info[file].type = UNOPEN;
-    my_free(my_file_info[file].name);
+    my_free(name);
   }
-  mysql_mutex_unlock(&THR_LOCK_open);
   DBUG_RETURN(err);
 } /* my_fclose */
 
@@ -215,13 +221,12 @@ FILE *my_fdopen(File Filedes, const char *name, int Flags, myf MyFlags)
   }
   else
   {
-    mysql_mutex_lock(&THR_LOCK_open);
-    my_stream_opened++;
+    statistic_increment(my_stream_opened, &THR_LOCK_open);
     if ((uint) Filedes < (uint) my_file_limit)
     {
       if (my_file_info[Filedes].type != UNOPEN)
       {
-        my_file_opened--;		/* File is opened with my_open ! */
+        statistic_decrement(my_file_opened, &THR_LOCK_open);		/* File is opened with my_open ! */
       }
       else
       {
@@ -229,7 +234,6 @@ FILE *my_fdopen(File Filedes, const char *name, int Flags, myf MyFlags)
       }
       my_file_info[Filedes].type = STREAM_BY_FDOPEN;
     }
-    mysql_mutex_unlock(&THR_LOCK_open);
   }
 
   DBUG_PRINT("exit",("stream: %p", fd));