unix4lyfe git - darkstat-debian/blob - hosts_sort.c

   1 /* darkstat 3
   2  * copyright (c) 2001-2012 Emil Mikulic.
   3  *
   4  * hosts_sort.c: quicksort a table of buckets.
   5  *
   6  * You may use, modify and redistribute this file under the terms of the
   7  * GNU General Public License version 2. (see COPYING.GPL)
   8  */
   9
  10 #include "cdefs.h"
  11 #include "err.h"
  12 #include "hosts_db.h"
  13
  14 static int cmp_u64(const uint64_t a, const uint64_t b) {
  15    if (a < b) return (1);
  16    if (a > b) return (-1);
  17    return (0);
  18 }
  19
  20 static int cmp_i64(const int64_t a, const int64_t b) {
  21    if (a < b) return (1);
  22    if (a > b) return (-1);
  23    return (0);
  24 }
  25
  26 /* Comparator for sorting 'struct bucket' */
  27 static int cmp(const struct bucket * const *x, const struct bucket * const *y,
  28     const enum sort_dir dir) {
  29    switch (dir) {
  30       case IN:
  31          return cmp_u64((*x)->in, (*y)->in);
  32       case OUT:
  33          return cmp_u64((*x)->out, (*y)->out);
  34       case TOTAL:
  35          return cmp_u64((*x)->total, (*y)->total);
  36       case LASTSEEN:
  37          return cmp_i64((*x)->u.host.last_seen_mono,
  38                         (*y)->u.host.last_seen_mono);
  39       default:
  40          errx(1, "cmp: unknown direction: %d", dir);
  41    }
  42 }
  43
  44 /*
  45  * The quicksort code is derived from FreeBSD's
  46  * src/lib/libc/stdlib/qsort.c v1.12
  47  */
  48
  49 /*-
  50  * Copyright (c) 1992, 1993
  51  *     The Regents of the University of California.  All rights reserved.
  52  *
  53  * Redistribution and use in source and binary forms, with or without
  54  * modification, are permitted provided that the following conditions
  55  * are met:
  56  * 1. Redistributions of source code must retain the above copyright
  57  *    notice, this list of conditions and the following disclaimer.
  58  * 2. Redistributions in binary form must reproduce the above copyright
  59  *    notice, this list of conditions and the following disclaimer in the
  60  *    documentation and/or other materials provided with the distribution.
  61  * 3. All advertising materials mentioning features or use of this software
  62  *    must display the following acknowledgement:
  63  *     This product includes software developed by the University of
  64  *     California, Berkeley and its contributors.
  65  * 4. Neither the name of the University nor the names of its contributors
  66  *    may be used to endorse or promote products derived from this software
  67  *    without specific prior written permission.
  68  *
  69  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  70  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  71  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  72  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  73  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  74  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  75  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  76  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  77  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  78  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  79  * SUCH DAMAGE.
  80  */
  81
  82 static void
  83 vecswap(const struct bucket **pi, const struct bucket **pj, int n)
  84 {
  85    if (n <= 0)
  86       return;
  87
  88    do {
  89       const struct bucket *t = *pi;
  90       *pi++ = *pj;
  91       *pj++ = t;
  92    } while (--n > 0);
  93 }
  94
  95 #define swap(a, b) { \
  96    const struct bucket *t = *(const struct bucket **)(a); \
  97    *(const struct bucket **)(a) = *(const struct bucket **)(b); \
  98    *(const struct bucket **)(b) = t; \
  99 }
 100
 101 static const struct bucket **
 102 med3(const struct bucket **a,
 103      const struct bucket **b,
 104      const struct bucket **c,
 105      const enum sort_dir dir)
 106 {
 107    return (cmp(a, b, dir) < 0)
 108     ? (cmp(b, c, dir) < 0 ? b : (cmp(a, c, dir) < 0 ? c : a ))
 109     : (cmp(b, c, dir) > 0 ? b : (cmp(a, c, dir) < 0 ? a : c ));
 110 }
 111
 112 /* Partial sort - only sort elements in the range [left:right] */
 113 void
 114 qsort_buckets(const struct bucket **a, size_t n,
 115    size_t left, size_t right,
 116    const enum sort_dir dir)
 117 {
 118         const struct bucket **pa, **pb, **pc, **pd, **pl, **pm, **pn;
 119         int d, r, swap_cnt;
 120
 121 loop:
 122         swap_cnt = 0;
 123         if (n < 7) {
 124                 for (pm = a+1; pm < a+n; pm++)
 125                         for (pl = pm;
 126                              (pl > a) && (cmp(pl-1, pl, dir) > 0);
 127                              pl--)
 128                                 swap(pl, pl-1);
 129                 return;
 130         }
 131         pm = a + (n / 2);
 132         if (n > 7) {
 133                 pl = a;
 134                 pn = a + (n - 1);
 135                 if (n > 40) {
 136                         d = (n / 8);
 137                         pl = med3(pl, pl + d, pl + 2 * d, dir);
 138                         pm = med3(pm - d, pm, pm + d, dir);
 139                         pn = med3(pn - 2 * d, pn - d, pn, dir);
 140                 }
 141                 pm = med3(pl, pm, pn, dir);
 142         }
 143         swap(a, pm);
 144         pa = pb = a + 1;
 145
 146         pc = pd = a + (n - 1);
 147         for (;;) {
 148                 while (pb <= pc && (r = cmp(pb, a, dir)) <= 0) {
 149                         if (r == 0) {
 150                                 swap_cnt = 1;
 151                                 swap(pa, pb);
 152                                 pa++;
 153                         }
 154                         pb++;
 155                 }
 156                 while (pb <= pc && (r = cmp(pc, a, dir)) >= 0) {
 157                         if (r == 0) {
 158                                 swap_cnt = 1;
 159                                 swap(pc, pd);
 160                                 pd--;
 161                         }
 162                         pc--;
 163                 }
 164                 if (pb > pc)
 165                         break;
 166                 swap(pb, pc);
 167                 swap_cnt = 1;
 168                 pb++;
 169                 pc--;
 170         }
 171         if (swap_cnt == 0) {  /* Switch to insertion sort */
 172                 for (pm = a + 1; pm < a+n; pm++)
 173                         for (pl = pm;
 174                              (pl > a) && (cmp(pl-1, pl, dir) > 0);
 175                              pl--)
 176                                 swap(pl, pl-1);
 177                 return;
 178         }
 179
 180         pn = a + n;
 181         r = MIN(pa - a, pb - pa);
 182         vecswap(a, pb - r, r);
 183         r = MIN(pd - pc, pn - pd - 1);
 184         vecswap(pb, pn - r, r);
 185         if (((r = pb - pa) > 1) && ((unsigned)r >= left))
 186                 qsort_buckets(a, r, left, right, dir);
 187         if (((r = pd - pc) > 1) && (n - r <= right)) {
 188                 /* Iterate rather than recurse to save stack space */
 189                 if (n - r > left)
 190                         left = 0;
 191                 else
 192                         left -= n - r;
 193                 right -= n - r;
 194                 a += n - r;
 195                 n = r;
 196                 goto loop;
 197         }
 198 /*              qsort(pn - r, r, cmp);*/
 199 }
 200
 201 /* vim:set ts=3 sw=3 tw=78 expandtab: */