1 files changed, 79 insertions, 0 deletions
diff --git a/libpager/seqnos.c b/libpager/seqnos.c
new file mode 100644
index 00000000..cab2f33d
--- /dev/null
+++ b/libpager/seqnos.c
@@ -0,0 +1,79 @@
+/* Sequence number synchronization routines for pager library
+   Copyright (C) 1994, 2011 Free Software Foundation
+
+   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 "priv.h"
+#include <assert.h>
+
+/* The message with seqno SEQNO has just been dequeued for pager P;
+   wait until all preceding messages have had a chance and then
+   return.  */
+void
+_pager_wait_for_seqno (struct pager *p,
+		       mach_port_seqno_t seqno)
+{
+  while (seqno != p->seqno + 1)
+    {
+      p->waitingforseqno = 1;
+      pthread_cond_wait (&p->wakeup, &p->interlock);
+    }
+}
+
+
+/* Allow the next message for pager P (potentially blocked in
+   _pager_wait_for_seqno) to be handled.  */
+void
+_pager_release_seqno (struct pager *p,
+		      mach_port_seqno_t seqno)
+{
+  assert (seqno == p->seqno + 1);
+  p->seqno = seqno;
+  if (p->waitingforseqno)
+    {
+      p->waitingforseqno = 0;
+      pthread_cond_broadcast (&p->wakeup);
+    }
+}
+
+
+/* Just update the seqno.  */
+void
+_pager_update_seqno (mach_port_t object,
+                     mach_port_seqno_t seqno)
+{
+  struct pager *p;
+
+  p = ports_lookup_port (0, object, _pager_class);
+  _pager_update_seqno_p (p, seqno);
+  if (p)
+    ports_port_deref (p);
+}
+
+
+/* Just update the seqno, pointer version.  */
+void
+_pager_update_seqno_p (struct pager *p,
+                       mach_port_seqno_t seqno)
+{
+  if (p
+      && p->port.class == _pager_class)
+    {
+      pthread_mutex_lock (&p->interlock);
+      _pager_wait_for_seqno (p, seqno);
+      _pager_release_seqno (p, seqno);
+      pthread_mutex_unlock (&p->interlock);
+    }
+}