re PR libfortran/50016 (Drastic I/O performance regression on Windows)

2011-10-19  Janne Blomqvist  <jb@gcc.gnu.org>
            Kai Tietz  <ktietz@redhat.com>
            Tobias Burnus  <burnus@net-b.de>

        PR fortran/50016
        * io/unix.h (flush_sync): Add new libgfortran-internal
        * prototype.
        * io/unix.c (flush_sync): New function, which calls sflush and
        on MinGW(-w64) also _commit.
        (flush_all_units, flush_all_units_1): Replace sflush/_commit by
        flush_sync.
        * io/file_pos.c (st_flush): Replace sflush/_commit by
        * flush_sync.
        * io/intrinsics.c (flush_i4, flush_i8): Ditto.


Co-Authored-By: Kai Tietz <ktietz@redhat.com>
Co-Authored-By: Tobias Burnus <burnus@net-b.de>

From-SVN: r180199

5 files changed, 38 insertions, 31 deletions

diff --git a/libgfortran/ChangeLog b/libgfortran/ChangeLog
index 55a7370..916887b 100644
--- a/libgfortran/ChangeLog
+++ b/libgfortran/ChangeLog
@@ -1,3 +1,16 @@
+2011-10-19  Janne Blomqvist  <jb@gcc.gnu.org>
+	    Kai Tietz  <ktietz@redhat.com>
+	    Tobias Burnus  <burnus@net-b.de>
+
+	PR fortran/50016
+	* io/unix.h (flush_sync): Add new libgfortran-internal prototype.
+	* io/unix.c (flush_sync): New function, which calls sflush and
+	on MinGW(-w64) also _commit.
+	(flush_all_units, flush_all_units_1): Replace sflush/_commit by
+	flush_sync.
+	* io/file_pos.c (st_flush): Replace sflush/_commit by flush_sync.
+	* io/intrinsics.c (flush_i4, flush_i8): Ditto.
+
 2011-10-18  Tobias Burnus  <burnus@net-b.de>
 	    Janne Blomqvist  <jb@gcc.gnu.org>
 
diff --git a/libgfortran/io/file_pos.c b/libgfortran/io/file_pos.c
index 4efdc1f..da83aa5 100644
--- a/libgfortran/io/file_pos.c
+++ b/libgfortran/io/file_pos.c
@@ -451,11 +451,7 @@ st_flush (st_parameter_filepos *fpp)
       if (u->flags.form == FORM_FORMATTED)
         fbuf_flush (u, u->mode);
 
-      sflush (u->s);
-#ifdef _WIN32
-      /* Without _commit, changes are not visible to other file descriptors.  */
-      _commit (u->s->fd);
-#endif
+      flush_sync (u->s);
       unlock_unit (u);
     }
   else
diff --git a/libgfortran/io/intrinsics.c b/libgfortran/io/intrinsics.c
index eaf2e17..2d00a66 100644
--- a/libgfortran/io/intrinsics.c
+++ b/libgfortran/io/intrinsics.c
@@ -206,12 +206,7 @@ flush_i4 (GFC_INTEGER_4 *unit)
       us = find_unit (*unit);
       if (us != NULL)
 	{
-	  sflush (us->s);
-#ifdef _WIN32
-	  /* Without _commit, changes are not visible
-	     to other file descriptors.  */
-	  _commit (u->s->fd);
-#endif
+	  flush_sync (us->s);
 	  unlock_unit (us);
 	}
     }
@@ -234,12 +229,7 @@ flush_i8 (GFC_INTEGER_8 *unit)
       us = find_unit (*unit);
       if (us != NULL)
 	{
-	  sflush (us->s);
-#ifdef _WIN32
-	  /* Without _commit, changes are not visible
-	     to other file descriptors.  */
-	  _commit (u->s->fd);
-#endif
+	  flush_sync (us->s);
 	  unlock_unit (us);
 	}
     }
diff --git a/libgfortran/io/unix.c b/libgfortran/io/unix.c
index 79bb9e9..26bb06a 100644
--- a/libgfortran/io/unix.c
+++ b/libgfortran/io/unix.c
@@ -1522,6 +1522,23 @@ retry:
   return u;
 }
 
+
+/* Flush dirty data, making sure that OS metadata is updated as
+   well. Note that this is VERY slow on mingw due to committing data
+   to stable storage.  */
+int
+flush_sync (stream * s)
+{
+  if (sflush (s) == -1)
+    return -1;
+#ifdef __MINGW32__
+  if (_commit (((unix_stream *)s)->fd) == -1)
+    return -1;
+#endif
+  return 0;
+}
+
+
 static gfc_unit *
 flush_all_units_1 (gfc_unit *u, int min_unit)
 {
@@ -1538,14 +1555,7 @@ flush_all_units_1 (gfc_unit *u, int min_unit)
 	  if (__gthread_mutex_trylock (&u->lock))
 	    return u;
 	  if (u->s)
-	    {
-	      sflush (u->s);
-#ifdef _WIN32
-	      /* Without _commit, changes are not visible to other
-		 file descriptors.  */
-	      _commit (u->s->fd);
-#endif
-	    }
+	    flush_sync (u->s);
 	  __gthread_mutex_unlock (&u->lock);
 	}
       u = u->right;
@@ -1575,12 +1585,7 @@ flush_all_units (void)
 
       if (u->closed == 0)
 	{
-	  sflush (u->s);
-#ifdef _WIN32
-	  /* Without _commit, changes are not visible to other
-	     file descriptors.  */
-	  _commit (u->s->fd);
-#endif
+	  flush_sync (u->s);
 	  __gthread_mutex_lock (&unit_lock);
 	  __gthread_mutex_unlock (&u->lock);
 	  (void) predec_waiting_locked (u);
diff --git a/libgfortran/io/unix.h b/libgfortran/io/unix.h
index f7d6f08..5e42268 100644
--- a/libgfortran/io/unix.h
+++ b/libgfortran/io/unix.h
@@ -167,6 +167,9 @@ internal_proto(is_special);
 extern void flush_if_preconnected (stream *);
 internal_proto(flush_if_preconnected);
 
+extern int flush_sync (stream *);
+internal_proto(flush_sync);
+
 extern int stream_isatty (stream *);
 internal_proto(stream_isatty);