summaryrefslogtreecommitdiff
path: root/ot_vector.c
blob: 6c7c9b0d26a182e0809f9987578123f1c81caebc (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
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
   It is considered beerware. Prost. Skol. Cheers or whatever.

   $id$ */

/* System */
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <stdint.h>

/* Opentracker */
#include "trackerlogic.h"
#include "ot_vector.h"

/* Libowfat */
#include "uint32.h"
#include "uint16.h"

static int vector_compare_peer(const void *peer1, const void *peer2 ) {
  return memcmp( peer1, peer2, OT_PEER_COMPARE_SIZE );
}

/* This function gives us a binary search that returns a pointer, even if
   no exact match is found. In that case it sets exactmatch 0 and gives
   calling functions the chance to insert data
*/
void *binary_search( const void * const key, const void * base, const size_t member_count, const size_t member_size,
                     size_t compare_size, int *exactmatch ) {
  size_t interval = member_count;

  while( interval ) {
    uint8_t *lookat = ((uint8_t*)base) + member_size * ( interval / 2 );
    int cmp = memcmp( lookat, key, compare_size );
    if(cmp == 0 ) {
      base = lookat;
      break;
    }
    if(cmp < 0) {
      base = lookat + member_size;
      interval--;
    }
    interval /= 2;
  }

  *exactmatch = interval;
  return (void*)base;
}

static uint8_t vector_hash_peer( ot_peer *peer, int bucket_count ) {
  unsigned int hash = 5381, i = OT_PEER_COMPARE_SIZE;
  uint8_t *p = (uint8_t*)peer;
  while( i-- ) hash += (hash<<5) + *(p++);
  return hash % bucket_count;
}

/* This is the generic insert operation for our vector type.
   It tries to locate the object at "key" with size "member_size" by comparing its first "compare_size" bytes with
   those of objects in vector. Our special "binary_search" function does that and either returns the match or a
   pointer to where the object is to be inserted. vector_find_or_insert makes space for the object and copies it,
   if it wasn't found in vector. Caller needs to check the passed "exactmatch" variable to see, whether an insert
   took place. If resizing the vector failed, NULL is returned, else the pointer to the object in vector.
*/
void *vector_find_or_insert( ot_vector *vector, void *key, size_t member_size, size_t compare_size, int *exactmatch ) {
  uint8_t *match = binary_search( key, vector->data, vector->size, member_size, compare_size, exactmatch );

  if( *exactmatch ) return match;

  if( vector->size + 1 > vector->space ) {
    size_t   new_space = vector->space ? OT_VECTOR_GROW_RATIO * vector->space : OT_VECTOR_MIN_MEMBERS;
    uint8_t *new_data = realloc( vector->data, new_space * member_size );
    if( !new_data ) return NULL;
    /* Adjust pointer if it moved by realloc */
    match = new_data + (match - (uint8_t*)vector->data);

    vector->data = new_data;
    vector->space = new_space;
  }
  memmove( match + member_size, match, ((uint8_t*)vector->data) + member_size * vector->size - match );

  vector->size++;
  return match;
}

ot_peer *vector_find_or_insert_peer( ot_vector *vector, ot_peer *peer, int *exactmatch ) {
  ot_peer *match;

  /* If space is zero but size is set, we're dealing with a list of vector->size buckets */
  if( vector->space < vector->size )
    vector = ((ot_vector*)vector->data) + vector_hash_peer(peer, vector->size );
  match = (ot_peer*)binary_search( peer, vector->data, vector->size, sizeof(ot_peer), OT_PEER_COMPARE_SIZE, exactmatch );

  if( *exactmatch ) return match;

  if( vector->size + 1 > vector->space ) {
    size_t   new_space = vector->space ? OT_VECTOR_GROW_RATIO * vector->space : OT_VECTOR_MIN_MEMBERS;
    ot_peer *new_data = realloc( vector->data, new_space * sizeof(ot_peer) );
    if( !new_data ) return NULL;
    /* Adjust pointer if it moved by realloc */
    match = new_data + (match - (ot_peer*)vector->data);

    vector->data = new_data;
    vector->space = new_space;
  }
  memmove( match + 1, match, sizeof(ot_peer) * ( ((ot_peer*)vector->data) + vector->size - match ) );

  vector->size++;
  return match;
}

/* This is the non-generic delete from vector-operation specialized for peers in pools.
   It returns 0 if no peer was found (and thus not removed)
              1 if a non-seeding peer was removed
              2 if a seeding peer was removed
*/
int vector_remove_peer( ot_vector *vector, ot_peer *peer ) {
  int      exactmatch;
  ot_peer *match, *end;

  if( !vector->size ) return 0;

  /* If space is zero but size is set, we're dealing with a list of vector->size buckets */
  if( vector->space < vector->size )
    vector = ((ot_vector*)vector->data) + vector_hash_peer(peer, vector->size );

  end = ((ot_peer*)vector->data) + vector->size;
  match = (ot_peer*)binary_search( peer, vector->data, vector->size, sizeof(ot_peer), OT_PEER_COMPARE_SIZE, &exactmatch );
  if( !exactmatch ) return 0;

  exactmatch = ( OT_PEERFLAG( match ) & PEER_FLAG_SEEDING ) ? 2 : 1;
  memmove( match, match + 1, sizeof(ot_peer) * ( end - match - 1 ) );

  vector->size--;
  vector_fixup_peers( vector );
  return exactmatch;
}

void vector_remove_torrent( ot_vector *vector, ot_torrent *match ) {
  ot_torrent *end = ((ot_torrent*)vector->data) + vector->size;

  if( !vector->size ) return;

  /* If this is being called after a unsuccessful malloc() for peer_list
     in add_peer_to_torrent, match->peer_list actually might be NULL */
  if( match->peer_list) free_peerlist( match->peer_list );

  memmove( match, match + 1, sizeof(ot_torrent) * ( end - match - 1 ) );
  if( ( --vector->size * OT_VECTOR_SHRINK_THRESH < vector->space ) && ( vector->space >= OT_VECTOR_SHRINK_RATIO * OT_VECTOR_MIN_MEMBERS ) ) {
    vector->space /= OT_VECTOR_SHRINK_RATIO;
    vector->data = realloc( vector->data, vector->space * sizeof( ot_torrent ) );
  }
}

void vector_clean_list( ot_vector * vector, int num_buckets ) {
  while( num_buckets-- )
    free( vector[num_buckets].data );
  free( vector );
  return;
}

void vector_redistribute_buckets( ot_peerlist * peer_list ) {
  int tmp, bucket, bucket_size_new, num_buckets_new, num_buckets_old = 1;
  ot_vector * bucket_list_new, * bucket_list_old = &peer_list->peers;

  if( OT_PEERLIST_HASBUCKETS( peer_list ) ) {
    num_buckets_old = peer_list->peers.size;
    bucket_list_old = peer_list->peers.data;
  }

  if( peer_list->peer_count < 255 )
    num_buckets_new = 1;
  else if( peer_list->peer_count > 8192 )
    num_buckets_new = 64;
  else if( peer_list->peer_count >= 512 && peer_list->peer_count < 4096 )
    num_buckets_new = 16;
  else if( peer_list->peer_count < 512 && num_buckets_old <= 16 )
    num_buckets_new = num_buckets_old;
  else if( peer_list->peer_count < 512 )
    num_buckets_new = 1;
  else if( peer_list->peer_count < 8192 && num_buckets_old > 1 )
    num_buckets_new = num_buckets_old;
  else
    num_buckets_new = 16;

  if( num_buckets_new == num_buckets_old )
    return;

  /* Assume near perfect distribution */
  bucket_list_new = malloc( num_buckets_new * sizeof( ot_vector ) );
  if( !bucket_list_new) return;
  bzero( bucket_list_new, num_buckets_new * sizeof( ot_vector ) );

  tmp = peer_list->peer_count / num_buckets_new;
  bucket_size_new = OT_VECTOR_MIN_MEMBERS;
  while( bucket_size_new < tmp)
    bucket_size_new *= OT_VECTOR_GROW_RATIO;

  /* preallocate vectors to hold all peers */
  for( bucket=0; bucket<num_buckets_new; ++bucket ) {
    bucket_list_new[bucket].space = bucket_size_new;
    bucket_list_new[bucket].data  = malloc( bucket_size_new * sizeof(ot_peer) );
    if( !bucket_list_new[bucket].data )
      return vector_clean_list( bucket_list_new, num_buckets_new );
  }

  /* Now sort them into the correct bucket */
  for( bucket=0; bucket<num_buckets_old; ++bucket ) {
    ot_peer * peers_old = bucket_list_old[bucket].data, * peers_new;
    int peer_count_old = bucket_list_old[bucket].size;
    while( peer_count_old-- ) {
      ot_vector * bucket_dest = bucket_list_new;
      if( num_buckets_new > 1 )
        bucket_dest += vector_hash_peer(peers_old, num_buckets_new);
      if( bucket_dest->size + 1 > bucket_dest->space ) {
        void * tmp = realloc( bucket_dest->data, sizeof(ot_peer) * OT_VECTOR_GROW_RATIO * bucket_dest->space );
        if( !tmp ) return vector_clean_list( bucket_list_new, num_buckets_new );
        bucket_dest->data   = tmp;
        bucket_dest->space *= OT_VECTOR_GROW_RATIO;
      }
      peers_new = (ot_peer*)bucket_dest->data;
      memcpy(peers_new + bucket_dest->size++, peers_old++, sizeof(ot_peer));
    }
  }

  /* Now sort each bucket to later allow bsearch */
  for( bucket=0; bucket<num_buckets_new; ++bucket )
    qsort( bucket_list_new[bucket].data, bucket_list_new[bucket].size, sizeof( ot_peer ), vector_compare_peer );

  /* Everything worked fine. Now link new bucket_list to peer_list */
  if( OT_PEERLIST_HASBUCKETS( peer_list) )
    vector_clean_list( (ot_vector*)peer_list->peers.data, peer_list->peers.size );
  else
    free( peer_list->peers.data );

  if( num_buckets_new > 1 ) {
    peer_list->peers.data  = bucket_list_new;
    peer_list->peers.size  = num_buckets_new;
    peer_list->peers.space = 0; /* Magic marker for "is list of buckets" */
  } else {
    peer_list->peers.data  = bucket_list_new->data;
    peer_list->peers.size  = bucket_list_new->size;
    peer_list->peers.space = bucket_list_new->space;
    free( bucket_list_new );
  }
}

void vector_fixup_peers( ot_vector * vector ) {
  int need_fix = 0;

  if( !vector->size ) {
    free( vector->data );
    vector->data = NULL;
    vector->space = 0;
    return;
  }

  while( ( vector->size * OT_VECTOR_SHRINK_THRESH < vector->space ) &&
         ( vector->space >= OT_VECTOR_SHRINK_RATIO * OT_VECTOR_MIN_MEMBERS ) ) {
    vector->space /= OT_VECTOR_SHRINK_RATIO;
    need_fix++;
  }
  if( need_fix )
    vector->data = realloc( vector->data, vector->space * sizeof( ot_peer ) );
}

const char *g_version_vector_c = "$Source: /home/cvsroot/opentracker/ot_vector.c,v $: $Revision: 1.20 $\n";