/*
 * Copyright (c) 2015-16  David Lamparter, for NetDEF, Inc.
 *
 * This file is part of Quagga
 *
 * Quagga 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.
 *
 * Quagga 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; see the file COPYING; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include <zebra.h>

#include "thread.h"
#include "memory.h"
#include "hash.h"
#include "log.h"
#include "qobj.h"

static pthread_rwlock_t nodes_lock;
static struct hash *nodes = NULL;

static unsigned int qobj_key (void *data)
{
  struct qobj_node *node = data;
  return (unsigned int)node->nid;
}

static int qobj_cmp (const void *a, const void *b)
{
  const struct qobj_node *na = a, *nb = b;
  return na->nid == nb->nid;
}

void qobj_reg(struct qobj_node *node, struct qobj_nodetype *type)
{
  node->type = type;
  pthread_rwlock_wrlock (&nodes_lock);
  do
    {
      node->nid  = (uint64_t)random();
      node->nid ^= (uint64_t)random() << 32;
    }
  while (!node->nid || hash_get (nodes, node, hash_alloc_intern) != node);
  pthread_rwlock_unlock (&nodes_lock);
}

void qobj_unreg(struct qobj_node *node)
{
  pthread_rwlock_wrlock (&nodes_lock);
  hash_release (nodes, node);
  pthread_rwlock_unlock (&nodes_lock);
}

struct qobj_node *qobj_get(uint64_t id)
{
  struct qobj_node dummy = { .nid = id }, *rv;
  pthread_rwlock_rdlock (&nodes_lock);
  rv = hash_lookup (nodes, &dummy);
  pthread_rwlock_unlock (&nodes_lock);
  return rv;
}

void *qobj_get_typed(uint64_t id, struct qobj_nodetype *type)
{
  struct qobj_node dummy = { .nid = id };
  struct qobj_node *node;
  void *rv;

  pthread_rwlock_rdlock (&nodes_lock);
  node = hash_lookup (nodes, &dummy);

  /* note: we explicitly hold the lock until after we have checked the type.
   * if the caller holds a lock that for example prevents the deletion of
   * route-maps, we can still race against a delete of something that isn't
   * a route-map. */
  if (!node || node->type != type)
    rv = NULL;
  else
    rv = (char *)node - node->type->node_member_offset;

  pthread_rwlock_unlock (&nodes_lock);
  return rv;
}

void qobj_init (void)
{
  if (!nodes)
    {
      pthread_rwlock_init (&nodes_lock, NULL);
      nodes = hash_create (qobj_key, qobj_cmp, NULL);
    }
}

void qobj_finish (void)
{
  hash_clean (nodes, NULL);
  hash_free (nodes);
  nodes = NULL;
  pthread_rwlock_destroy (&nodes_lock);
}