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

   1 /* darkstat 3
   2  * copyright (c) 2001-2011 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 /* ---------------------------------------------------------------------------
  15  * comparator for sorting (biggest first)
  16  */
  17 static int
  18 cmp(const struct bucket * const *x, const struct bucket * const *y,
  19     const enum sort_dir dir)
  20 {
  21    uint64_t a, b;
  22
  23    switch (dir) {
  24    case IN:
  25       a = (*x)->in;
  26       b = (*y)->in;
  27       break;
  28    case OUT:
  29       a = (*x)->out;
  30       b = (*y)->out;
  31       break;
  32    case TOTAL:
  33       a = (*x)->total;
  34       b = (*y)->total;
  35       break;
  36    case LASTSEEN:
  37       a = (*x)->u.host.last_seen_mono;
  38       b = (*y)->u.host.last_seen_mono;
  39       break;
  40    default:
  41       errx(1, "cmp: unknown direction: %d", dir);
  42    }
  43
  44    if (a < b) return (1);
  45    else if (a > b) return (-1);
  46    else return (0);
  47 }
  48
  49 /*
  50  * The quicksort code is derived from FreeBSD's
  51  * src/lib/libc/stdlib/qsort.c v1.12
  52  */
  53
  54 /*-
  55  * Copyright (c) 1992, 1993
  56  *     The Regents of the University of California.  All rights reserved.
  57  *
  58  * Redistribution and use in source and binary forms, with or without
  59  * modification, are permitted provided that the following conditions
  60  * are met:
  61  * 1. Redistributions of source code must retain the above copyright
  62  *    notice, this list of conditions and the following disclaimer.
  63  * 2. Redistributions in binary form must reproduce the above copyright
  64  *    notice, this list of conditions and the following disclaimer in the
  65  *    documentation and/or other materials provided with the distribution.
  66  * 3. All advertising materials mentioning features or use of this software
  67  *    must display the following acknowledgement:
  68  *     This product includes software developed by the University of
  69  *     California, Berkeley and its contributors.
  70  * 4. Neither the name of the University nor the names of its contributors
  71  *    may be used to endorse or promote products derived from this software
  72  *    without specific prior written permission.
  73  *
  74  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  75  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  76  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  77  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  78  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  79  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  80  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  81  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  82  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  83  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  84  * SUCH DAMAGE.
  85  */
  86
  87 static void
  88 vecswap(const struct bucket **pi, const struct bucket **pj, int n)
  89 {
  90    if (n <= 0)
  91       return;
  92
  93    do {
  94       const struct bucket *t = *pi;
  95       *pi++ = *pj;
  96       *pj++ = t;
  97    } while (--n > 0);
  98 }
  99
 100 #define swap(a, b) { \
 101    const struct bucket *t = *(const struct bucket **)(a); \
 102    *(const struct bucket **)(a) = *(const struct bucket **)(b); \
 103    *(const struct bucket **)(b) = t; \
 104 }
 105
 106 static const struct bucket **
 107 med3(const struct bucket **a,
 108      const struct bucket **b,
 109      const struct bucket **c,
 110      const enum sort_dir dir)
 111 {
 112    return (cmp(a, b, dir) < 0)
 113     ? (cmp(b, c, dir) < 0 ? b : (cmp(a, c, dir) < 0 ? c : a ))
 114     : (cmp(b, c, dir) > 0 ? b : (cmp(a, c, dir) < 0 ? a : c ));
 115 }
 116
 117 /* Partial sort - only sort elements in the range [left:right] */
 118 void
 119 qsort_buckets(const struct bucket **a, size_t n,
 120    size_t left, size_t right,
 121    const enum sort_dir dir)
 122 {
 123         const struct bucket **pa, **pb, **pc, **pd, **pl, **pm, **pn;
 124         int d, r, swap_cnt;
 125
 126 loop:
 127         swap_cnt = 0;
 128         if (n < 7) {
 129                 for (pm = a+1; pm < a+n; pm++)
 130                         for (pl = pm;
 131                              (pl > a) && (cmp(pl-1, pl, dir) > 0);
 132                              pl--)
 133                                 swap(pl, pl-1);
 134                 return;
 135         }
 136         pm = a + (n / 2);
 137         if (n > 7) {
 138                 pl = a;
 139                 pn = a + (n - 1);
 140                 if (n > 40) {
 141                         d = (n / 8);
 142                         pl = med3(pl, pl + d, pl + 2 * d, dir);
 143                         pm = med3(pm - d, pm, pm + d, dir);
 144                         pn = med3(pn - 2 * d, pn - d, pn, dir);
 145                 }
 146                 pm = med3(pl, pm, pn, dir);
 147         }
 148         swap(a, pm);
 149         pa = pb = a + 1;
 150
 151         pc = pd = a + (n - 1);
 152         for (;;) {
 153                 while (pb <= pc && (r = cmp(pb, a, dir)) <= 0) {
 154                         if (r == 0) {
 155                                 swap_cnt = 1;
 156                                 swap(pa, pb);
 157                                 pa++;
 158                         }
 159                         pb++;
 160                 }
 161                 while (pb <= pc && (r = cmp(pc, a, dir)) >= 0) {
 162                         if (r == 0) {
 163                                 swap_cnt = 1;
 164                                 swap(pc, pd);
 165                                 pd--;
 166                         }
 167                         pc--;
 168                 }
 169                 if (pb > pc)
 170                         break;
 171                 swap(pb, pc);
 172                 swap_cnt = 1;
 173                 pb++;
 174                 pc--;
 175         }
 176         if (swap_cnt == 0) {  /* Switch to insertion sort */
 177                 for (pm = a + 1; pm < a+n; pm++)
 178                         for (pl = pm;
 179                              (pl > a) && (cmp(pl-1, pl, dir) > 0);
 180                              pl--)
 181                                 swap(pl, pl-1);
 182                 return;
 183         }
 184
 185         pn = a + n;
 186         r = MIN(pa - a, pb - pa);
 187         vecswap(a, pb - r, r);
 188         r = MIN(pd - pc, pn - pd - 1);
 189         vecswap(pb, pn - r, r);
 190         if (((r = pb - pa) > 1) && ((unsigned)r >= left))
 191                 qsort_buckets(a, r, left, right, dir);
 192         if (((r = pd - pc) > 1) && (n - r <= right)) {
 193                 /* Iterate rather than recurse to save stack space */
 194                 if (n - r > left)
 195                         left = 0;
 196                 else
 197                         left -= n - r;
 198                 right -= n - r;
 199                 a += n - r;
 200                 n = r;
 201                 goto loop;
 202         }
 203 /*              qsort(pn - r, r, cmp);*/
 204 }
 205
 206 /* vim:set ts=3 sw=3 tw=78 expandtab: */