git.sur5r.net Git - openldap/blob - libraries/libmdb/midl.c

   1 /**     @file midl.c
   2  *      @brief ldap bdb back-end ID List functions */
   3 /* $OpenLDAP$ */
   4 /* This work is part of OpenLDAP Software <http://www.openldap.org/>.
   5  *
   6  * Copyright 2000-2011 The OpenLDAP Foundation.
   7  * All rights reserved.
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted only as authorized by the OpenLDAP
  11  * Public License.
  12  *
  13  * A copy of this license is available in the file LICENSE in the
  14  * top-level directory of the distribution or, alternatively, at
  15  * <http://www.OpenLDAP.org/license.html>.
  16  */
  17
  18 #include <limits.h>
  19 #include <string.h>
  20 #include <sys/types.h>
  21 #include <assert.h>
  22 #include "midl.h"
  23
  24 /** @defgroup internal  MDB Internals
  25  *      @{
  26  */
  27 /** @defgroup idls      ID List Management
  28  *      @{
  29  */
  30 #define CMP(x,y)         ( (x) < (y) ? -1 : (x) > (y) )
  31
  32 #if 0   /* superseded by append/sort */
  33 static unsigned mdb_midl_search( IDL ids, ID id )
  34 {
  35         /*
  36          * binary search of id in ids
  37          * if found, returns position of id
  38          * if not found, returns first position greater than id
  39          */
  40         unsigned base = 0;
  41         unsigned cursor = 0;
  42         int val = 0;
  43         unsigned n = ids[0];
  44
  45         while( 0 < n ) {
  46                 int pivot = n >> 1;
  47                 cursor = base + pivot;
  48                 val = CMP( ids[cursor + 1], id );
  49
  50                 if( val < 0 ) {
  51                         n = pivot;
  52
  53                 } else if ( val > 0 ) {
  54                         base = cursor + 1;
  55                         n -= pivot + 1;
  56
  57                 } else {
  58                         return cursor + 1;
  59                 }
  60         }
  61
  62         if( val > 0 ) {
  63                 return cursor + 2;
  64         } else {
  65                 return cursor + 1;
  66         }
  67 }
  68
  69 int mdb_midl_insert( IDL ids, ID id )
  70 {
  71         unsigned x, i;
  72
  73         if (MDB_IDL_IS_RANGE( ids )) {
  74                 /* if already in range, treat as a dup */
  75                 if (id >= MDB_IDL_FIRST(ids) && id <= MDB_IDL_LAST(ids))
  76                         return -1;
  77                 if (id < MDB_IDL_FIRST(ids))
  78                         ids[1] = id;
  79                 else if (id > MDB_IDL_LAST(ids))
  80                         ids[2] = id;
  81                 return 0;
  82         }
  83
  84         x = mdb_midl_search( ids, id );
  85         assert( x > 0 );
  86
  87         if( x < 1 ) {
  88                 /* internal error */
  89                 return -2;
  90         }
  91
  92         if ( x <= ids[0] && ids[x] == id ) {
  93                 /* duplicate */
  94                 assert(0);
  95                 return -1;
  96         }
  97
  98         if ( ++ids[0] >= MDB_IDL_DB_MAX ) {
  99                 if( id < ids[1] ) {
 100                         ids[1] = id;
 101                         ids[2] = ids[ids[0]-1];
 102                 } else if ( ids[ids[0]-1] < id ) {
 103                         ids[2] = id;
 104                 } else {
 105                         ids[2] = ids[ids[0]-1];
 106                 }
 107                 ids[0] = NOID;
 108
 109         } else {
 110                 /* insert id */
 111                 for (i=ids[0]; i>x; i--)
 112                         ids[i] = ids[i-1];
 113                 ids[x] = id;
 114         }
 115
 116         return 0;
 117 }
 118 #endif
 119
 120 int mdb_midl_append( IDL ids, ID id )
 121 {
 122         /* Too big? */
 123         if (ids[0] >= MDB_IDL_UM_MAX)
 124                 return -1;
 125         ids[0]++;
 126         ids[ids[0]] = id;
 127         return 0;
 128 }
 129
 130 /* Quicksort + Insertion sort for small arrays */
 131
 132 #define SMALL   8
 133 #define SWAP(a,b)       { itmp=(a); (a)=(b); (b)=itmp; }
 134
 135 void
 136 mdb_midl_sort( ID *ids )
 137 {
 138         /* Max possible depth of int-indexed tree * 2 items/level */
 139         int istack[sizeof(int)*CHAR_BIT * 2];
 140         int i,j,k,l,ir,jstack;
 141         ID a, itmp;
 142
 143         ir = ids[0];
 144         l = 1;
 145         jstack = 0;
 146         for(;;) {
 147                 if (ir - l < SMALL) {   /* Insertion sort */
 148                         for (j=l+1;j<=ir;j++) {
 149                                 a = ids[j];
 150                                 for (i=j-1;i>=1;i--) {
 151                                         if (ids[i] >= a) break;
 152                                         ids[i+1] = ids[i];
 153                                 }
 154                                 ids[i+1] = a;
 155                         }
 156                         if (jstack == 0) break;
 157                         ir = istack[jstack--];
 158                         l = istack[jstack--];
 159                 } else {
 160                         k = (l + ir) >> 1;      /* Choose median of left, center, right */
 161                         SWAP(ids[k], ids[l+1]);
 162                         if (ids[l] < ids[ir]) {
 163                                 SWAP(ids[l], ids[ir]);
 164                         }
 165                         if (ids[l+1] < ids[ir]) {
 166                                 SWAP(ids[l+1], ids[ir]);
 167                         }
 168                         if (ids[l] < ids[l+1]) {
 169                                 SWAP(ids[l], ids[l+1]);
 170                         }
 171                         i = l+1;
 172                         j = ir;
 173                         a = ids[l+1];
 174                         for(;;) {
 175                                 do i++; while(ids[i] > a);
 176                                 do j--; while(ids[j] < a);
 177                                 if (j < i) break;
 178                                 SWAP(ids[i],ids[j]);
 179                         }
 180                         ids[l+1] = ids[j];
 181                         ids[j] = a;
 182                         jstack += 2;
 183                         if (ir-i+1 >= j-1) {
 184                                 istack[jstack] = ir;
 185                                 istack[jstack-1] = i;
 186                                 ir = j-1;
 187                         } else {
 188                                 istack[jstack] = j-1;
 189                                 istack[jstack-1] = l;
 190                                 l = i;
 191                         }
 192                 }
 193         }
 194 }
 195
 196 unsigned mdb_mid2l_search( ID2L ids, ID id )
 197 {
 198         /*
 199          * binary search of id in ids
 200          * if found, returns position of id
 201          * if not found, returns first position greater than id
 202          */
 203         unsigned base = 0;
 204         unsigned cursor = 0;
 205         int val = 0;
 206         unsigned n = ids[0].mid;
 207
 208         while( 0 < n ) {
 209                 int pivot = n >> 1;
 210                 cursor = base + pivot;
 211                 val = CMP( id, ids[cursor + 1].mid );
 212
 213                 if( val < 0 ) {
 214                         n = pivot;
 215
 216                 } else if ( val > 0 ) {
 217                         base = cursor + 1;
 218                         n -= pivot + 1;
 219
 220                 } else {
 221                         return cursor + 1;
 222                 }
 223         }
 224
 225         if( val > 0 ) {
 226                 return cursor + 2;
 227         } else {
 228                 return cursor + 1;
 229         }
 230 }
 231
 232 int mdb_mid2l_insert( ID2L ids, ID2 *id )
 233 {
 234         unsigned x, i;
 235
 236         x = mdb_mid2l_search( ids, id->mid );
 237         assert( x > 0 );
 238
 239         if( x < 1 ) {
 240                 /* internal error */
 241                 return -2;
 242         }
 243
 244         if ( x <= ids[0].mid && ids[x].mid == id->mid ) {
 245                 /* duplicate */
 246                 return -1;
 247         }
 248
 249         if ( ids[0].mid >= MDB_IDL_UM_MAX ) {
 250                 /* too big */
 251                 return -2;
 252
 253         } else {
 254                 /* insert id */
 255                 ids[0].mid++;
 256                 for (i=ids[0].mid; i>x; i--)
 257                         ids[i] = ids[i-1];
 258                 ids[x] = *id;
 259         }
 260
 261         return 0;
 262 }
 263 /** @} */
 264 /** @} */