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/* 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);
if (p)
{
pthread_mutex_lock (&p->interlock);
_pager_wait_for_seqno (p, seqno);
_pager_release_seqno (p, seqno);
pthread_mutex_unlock (&p->interlock);
ports_port_deref (p);
}
}
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