Initial revision

1 files changed, 110 insertions, 0 deletions

diff --git a/libdiskfs/sync-interval.c b/libdiskfs/sync-interval.c
new file mode 100644
index 00000000..770ccab7
--- /dev/null
+++ b/libdiskfs/sync-interval.c
@@ -0,0 +1,110 @@
+/* Support for periodic syncing
+
+   Copyright (C) 1995 Free Software Foundation, Inc.
+
+   Written by Miles Bader <miles@gnu.ai.mit.edu>
+
+   This program is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public License as
+   published by the Free Software Foundation; either version 2, or (at
+   your option) any later version.
+
+   This program is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
+
+#include <errno.h>
+#include <cthreads.h>
+#include <unistd.h>
+
+#include <hurd/fsys.h>
+
+#include "priv.h"
+
+/* The thread that's doing the syncing.  */
+cthread_t periodic_sync_thread = 0;
+
+/* A lock to lock before changing any of the above.  */
+spin_lock_t periodic_sync_lock = SPIN_LOCK_INITIALIZER;
+
+/* The filesystem control port to which we send our sync requests.  */
+mach_port_t control_port;
+
+/* ---------------------------------------------------------------- */
+
+static void periodic_sync ();
+
+/* Establish a thread to sync the filesystem every INTERVAL seconds, or
+   never, if INTERVAL is zero.  If an error occurs creating the thread, it is
+   returned, otherwise 0.  Subsequent calls will create a new thread and
+   (eventually) get rid of the old one; the old thread won't do any more
+   syncs, regardless.  */
+error_t
+diskfs_set_sync_interval (int interval)
+{
+  error_t err = 0;
+
+  spin_lock (&periodic_sync_lock);
+
+  if (control_port == MACH_PORT_NULL)
+    {
+      control_port =
+	ports_get_right (ports_allocate_port
+			 (sizeof (struct port_info), PT_CTL));
+      err =
+	mach_port_insert_right (mach_task_self (),
+				control_port, control_port,
+				MACH_MSG_TYPE_MAKE_SEND);
+    }
+
+  if (!err)
+    /* Here we just set the new thread; any existing thread will notice when it
+       wakes up and go away silently.  */
+    if (interval == 0)
+      periodic_sync_thread = 0;
+    else
+      {
+	periodic_sync_thread =
+	  cthread_fork ((cthread_fn_t)periodic_sync, (any_t)interval);
+	if (periodic_sync_thread)
+	  cthread_detach (periodic_sync_thread);
+	else
+	  err = ED;
+      }
+
+  spin_unlock (&periodic_sync_lock);
+
+  return 0;
+}
+
+/* ---------------------------------------------------------------- */
+
+/* Sync the filesystem (pointed to by the variable CONTROL_PORT above) every
+   INTERVAL seconds, as long as it's in the thread pointed to by the global
+   variable PERIODIC_SYNC_THREAD.   */
+static void
+periodic_sync (int interval)
+{
+  for (;;)
+    {
+      cthread_t thread;
+
+      spin_lock (&periodic_sync_lock);
+      thread = periodic_sync_thread;
+      spin_unlock (&periodic_sync_lock);
+
+      if (thread != cthread_self ())
+	/* We've been superseded as the sync thread...  Just die silently.  */
+	return;
+
+      fsys_syncfs (control_port, 0, 0);
+
+      /* Wait until next time.  */
+      sleep (interval);
+    }
+}