summaryrefslogtreecommitdiffstats
path: root/proto/ospf/topology.c
blob: db2065bbfc5c9ab032b89842dfae709d78d22742 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
/*
 *	BIRD -- OSPF Topological Database
 *
 *	(c) 1999 Martin Mares <mj@ucw.cz>
 *	(c) 1999 Ondrej Filip <feela@network.cz>
 *
 *	Can be freely distributed and used under the terms of the GNU GPL.
 */

#define LOCAL_DEBUG

#include <string.h>

#include "nest/bird.h"

#include "ospf.h"

#define HASH_DEF_ORDER 6		/* FIXME: Increase */
#define HASH_HI_MARK *4
#define HASH_HI_STEP 2
#define HASH_HI_MAX 16
#define HASH_LO_MARK /5
#define HASH_LO_STEP 2
#define HASH_LO_MIN 8

static void
ospf_top_ht_alloc(struct top_graph *f)
{
  f->hash_size = 1 << f->hash_order;
  f->hash_mask = f->hash_size - 1;
  if (f->hash_order > HASH_HI_MAX - HASH_HI_STEP)
    f->hash_entries_max = ~0;
  else
    f->hash_entries_max = f->hash_size HASH_HI_MARK;
  if (f->hash_order < HASH_LO_MIN + HASH_LO_STEP)
    f->hash_entries_min = 0;
  else
    f->hash_entries_min = f->hash_size HASH_LO_MARK;
  DBG("Allocating OSPF hash of order %d: %d hash_entries, %d low, %d high\n",
      f->hash_order, f->hash_size, f->hash_entries_min, f->hash_entries_max);
  f->hash_table = mb_alloc(f->pool, f->hash_size * sizeof(struct top_hash_entry *));
  bzero(f->hash_table, f->hash_size * sizeof(struct top_hash_entry *));
}

static inline void
ospf_top_ht_free(struct top_hash_entry **h)
{
  mb_free(h);
}

static inline u32
ospf_top_hash_u32(u32 a)
{
  /* Shamelessly stolen from IP address hashing in ipv4.h */
  a ^= a >> 16;
  a ^= a << 10;
  return a;
}

static inline unsigned
ospf_top_hash(struct top_graph *f, u32 lsaid, u32 rtrid, u32 type)
{
  return (ospf_top_hash_u32(lsaid) + ospf_top_hash_u32(rtrid) + type) & f->hash_mask;
}

struct top_graph *
ospf_top_new(struct proto_ospf *p)
{
  struct top_graph *f;

  f = mb_allocz(p->proto.pool, sizeof(struct top_graph));
  f->pool = p->proto.pool;
  f->hash_slab = sl_new(f->pool, sizeof(struct top_hash_entry));
  f->hash_order = HASH_DEF_ORDER;
  ospf_top_ht_alloc(f);
  f->hash_entries = 0;
  f->hash_entries_min = 0;
  return f;
}

void
ospf_top_free(struct top_graph *f)
{
  rfree(f->hash_slab);
  ospf_top_ht_free(f->hash_table);
  mb_free(f);
}

static void
ospf_top_rehash(struct top_graph *f, int step)
{
  unsigned int oldn, oldh;
  struct top_hash_entry **n, **oldt, **newt, *e, *x;

  oldn = f->hash_size;
  oldt = f->hash_table;
  DBG("Re-hashing topology hash from order %d to %d\n", f->hash_order, f->hash_order+step);
  f->hash_order += step;
  ospf_top_ht_alloc(f);
  newt = f->hash_table;

  for(oldh=0; oldh < oldn; oldh++)
    {
      e = oldt[oldh];
      while (e)
	{
	  x = e->next;
	  n = newt + ospf_top_hash(f, e->lsa_id, e->rtr_id, e->lsa_type);
	  e->next = *n;
	  *n = e;
	  e = x;
	}
    }
  ospf_top_ht_free(oldt);
}

struct top_hash_entry *
ospf_hash_find(struct top_graph *f, u32 lsa, u32 rtr, u32 type)
{
  struct top_hash_entry *e = f->hash_table[ospf_top_hash(f, lsa, rtr, type)];

  while (e && (e->lsa_id != lsa || e->rtr_id != rtr || e->lsa_type != type))
    e = e->next;
  return e;
}

struct top_hash_entry *
ospf_hash_get(struct top_graph *f, u32 lsa, u32 rtr, u32 type)
{
  struct top_hash_entry **ee = f->hash_table + ospf_top_hash(f, lsa, rtr, type);
  struct top_hash_entry *e = *ee;

  while (e && (e->lsa_id != lsa || e->rtr_id != rtr || e->lsa_type != type))
    e = e->next;
  if (e)
    return e;
  e = sl_alloc(f->hash_slab);
  e->lsa_id = lsa;
  e->rtr_id = rtr;
  e->lsa_type = type;
  e->vertex = NULL;
  if (f->hash_entries++ > f->hash_entries_max)
    ospf_top_rehash(f, HASH_HI_STEP);
  return e;
}

void
ospf_hash_delete(struct top_graph *f, struct top_hash_entry *e)
{
  unsigned int h = ospf_top_hash(f, e->lsa_id, e->rtr_id, e->lsa_type);
  struct top_hash_entry **ee = f->hash_table + h;

  while (*ee)
    {
      if (*ee == e)
	{
	  *ee = e->next;
	  sl_free(f->hash_slab, e);
	  if (f->hash_entries-- < f->hash_entries_min)
	    ospf_top_rehash(f, -HASH_LO_STEP);
	  return;
	}
      ee = &((*ee)->next);
    }
  bug("ospf_hash_delete() called for invalid node");
}

void
ospf_top_dump(struct top_graph *f)
{
  unsigned int i;

  for(i=0; i<f->hash_size; i++)
    {
      struct top_hash_entry *e = f->hash_table[i];
      while (e)
	{
	  debug("%04x %08x %08x %p\n", e->lsa_type, e->lsa_id, e->rtr_id, e->vertex);
	  e = e->next;
	}
    }
}