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rpmdb/merge.c
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    00001 /*@-mustmod -sizeoftype @*/
    00002 /*-
    00003  * Copyright (c) 1992, 1993
    00004  *      The Regents of the University of California.  All rights reserved.
    00005  *
    00006  * This code is derived from software contributed to Berkeley by
    00007  * Peter McIlroy.
    00008  *
    00009  * Redistribution and use in source and binary forms, with or without
    00010  * modification, are permitted provided that the following conditions
    00011  * are met:
    00012  * 1. Redistributions of source code must retain the above copyright
    00013  *    notice, this list of conditions and the following disclaimer.
    00014  * 2. Redistributions in binary form must reproduce the above copyright
    00015  *    notice, this list of conditions and the following disclaimer in the
    00016  *    documentation and/or other materials provided with the distribution.
    00017  * 3. All advertising materials mentioning features or use of this software
    00018  *    must display the following acknowledgement:
    00019  *      This product includes software developed by the University of
    00020  *      California, Berkeley and its contributors.
    00021  * 4. Neither the name of the University nor the names of its contributors
    00022  *    may be used to endorse or promote products derived from this software
    00023  *    without specific prior written permission.
    00024  *
    00025  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
    00026  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
    00027  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
    00028  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
    00029  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
    00030  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
    00031  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
    00032  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
    00033  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
    00034  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
    00035  * SUCH DAMAGE.
    00036  */
    00037
    00038 #if defined(LIBC_SCCS) && !defined(lint)
    00039 static char sccsid[] = "@(#)merge.c     8.2 (Berkeley) 2/14/94";
    00040 #endif /* LIBC_SCCS and not lint */
    00041
    00042 /*
    00043  * Hybrid exponential search/linear search merge sort with hybrid
    00044  * natural/pairwise first pass.  Requires about .3% more comparisons
    00045  * for random data than LSMS with pairwise first pass alone.
    00046  * It works for objects as small as two bytes.
    00047  */
    00048
    00049 #define NATURAL
    00050 #define THRESHOLD 16    /* Best choice for natural merge cut-off. */
    00051
    00052 /* #define NATURAL to get hybrid natural merge.
    00053  * (The default is pairwise merging.)
    00054  */
    00055
    00056 #include "system.h"
    00057
    00058 #include <rpmiotypes.h>
    00059 #include <rpmtag.h>
    00060 #include <rpmdb.h>
    00061
    00062 #include "debug.h"
    00063
    00064 #define ISIZE sizeof(int)
    00065 #define PSIZE sizeof(unsigned char *)
    00066 #define ICOPY_LIST(src, dst, last)                              \
    00067         do                                                      \
    00068         *(int*)dst = *(int*)src, src += ISIZE, dst += ISIZE;    \
    00069         while(src < last)
    00070 #define ICOPY_ELT(src, dst, i)                                  \
    00071         do                                                      \
    00072         *(int*) dst = *(int*) src, src += ISIZE, dst += ISIZE;  \
    00073         while (i -= ISIZE)
    00074
    00075 #define CCOPY_LIST(src, dst, last)              \
    00076         do                                      \
    00077                 *dst++ = *src++;                \
    00078         while (src < last)
    00079 #define CCOPY_ELT(src, dst, i)                  \
    00080         do                                      \
    00081                 *dst++ = *src++;                \
    00082         while (i -= 1)
    00083
    00084 /*
    00085  * Find the next possible pointer head.  (Trickery for forcing an array
    00086  * to do double duty as a linked list when objects do not align with word
    00087  * boundaries.
    00088  */
    00089 /* Assumption: PSIZE is a power of 2. */
    00090 #define EVAL(p) (unsigned char **)                                      \
    00091     ((unsigned char *)0 +                                               \
    00092         (((unsigned char *)p + PSIZE - 1 - (unsigned char *) 0) & ~(PSIZE - 1)))
    00093
    00094 #define swap(a, b) {                                    \
    00095                 s = b;                                  \
    00096                 i = (int) size;                         \
    00097                 do {                                    \
    00098                         tmp = *a; *a++ = *s; *s++ = tmp; \
    00099                 } while (--i);                          \
    00100                 a -= size;                              \
    00101         }
    00102 #define reverse(bot, top) {                             \
    00103         s = top;                                        \
    00104         do {                                            \
    00105                 i = (int) size;                         \
    00106                 do {                                    \
    00107                         tmp = *bot; *bot++ = *s; *s++ = tmp; \
    00108                 } while (--i);                          \
    00109                 s -= size2;                             \
    00110         } while(bot < s);                               \
    00111 }
    00112
    00113 /*
    00114  * This is to avoid out-of-bounds addresses in sorting the
    00115  * last 4 elements.
    00116  */
    00117 static void
    00118 insertionsort(unsigned char *a, size_t n, size_t size,
    00119                 int (*cmp) (const void *, const void *))
    00120         /*@modifies *a @*/
    00121 {
    00122         u_char *ai, *s, *t, *u, tmp;
    00123         int i;
    00124
    00125         for (ai = a+size; --n >= 1; ai += size)
    00126                 for (t = ai; t > a; t -= size) {
    00127                         u = t - size;
    00128                         if (cmp(u, t) <= 0)
    00129                                 /*@innerbreak@*/ break;
    00130                         swap(u, t);
    00131                 }
    00132 }
    00133
    00134 /*
    00135  * Optional hybrid natural/pairwise first pass.  Eats up list1 in runs of
    00136  * increasing order, list2 in a corresponding linked list.  Checks for runs
    00137  * when THRESHOLD/2 pairs compare with same sense.  (Only used when NATURAL
    00138  * is defined.  Otherwise simple pairwise merging is used.)
    00139  */
    00140 static void
    00141 setup(unsigned char *list1, /*@out@*/ unsigned char *list2,
    00142                 size_t n, size_t size, int (*cmp) (const void *, const void *))
    00143         /*@modifies list1, list2 @*/
    00144 {
    00145         int i, length, size2, sense;
    00146         unsigned char *f1, *f2, *s, *l2, *last, *p2, tmp;
    00147
    00148         size2 = size*2;
    00149         if (n <= 5) {
    00150                 insertionsort(list1, n, size, cmp);
    00151                 *EVAL(list2) = (unsigned char*) list2 + n*size;
    00152                 return;
    00153         }
    00154         /*
    00155          * Avoid running pointers out of bounds; limit n to evens
    00156          * for simplicity.
    00157          */
    00158         i = (int)(4 + (n & 1));
    00159         insertionsort(list1 + (n - i) * size, i, size, cmp);
    00160         last = list1 + size * (n - i);
    00161         *EVAL(list2 + (last - list1)) = list2 + n * size;
    00162
    00163 #ifdef NATURAL
    00164         p2 = list2;
    00165         f1 = list1;
    00166         sense = (cmp(f1, f1 + size) > 0);
    00167         for (; f1 < last; sense = !sense) {
    00168                 length = 2;
    00169                                         /* Find pairs with same sense. */
    00170                 for (f2 = f1 + size2; f2 < last; f2 += size2) {
    00171                         if ((cmp(f2, f2+ size) > 0) != sense)
    00172                                 /*@innerbreak@*/ break;
    00173                         length += 2;
    00174                 }
    00175                 if (length < THRESHOLD) {               /* Pairwise merge */
    00176                         do {
    00177                                 p2 = *EVAL(p2) = f1 + size2 - list1 + list2;
    00178                                 if (sense > 0)
    00179                                         swap (f1, f1 + size);
    00180                         } while ((f1 += size2) < f2);
    00181                 } else {                                /* Natural merge */
    00182                         l2 = f2;
    00183                         for (f2 = f1 + size2; f2 < l2; f2 += size2) {
    00184                                 if ((cmp(f2-size, f2) > 0) != sense) {
    00185                                         p2 = *EVAL(p2) = f2 - list1 + list2;
    00186                                         if (sense > 0)
    00187                                                 reverse(f1, f2-size);
    00188                                         f1 = f2;
    00189                                 }
    00190                         }
    00191                         if (sense > 0)
    00192                                 reverse (f1, f2-size);
    00193                         f1 = f2;
    00194                         if (f2 < last || cmp(f2 - size, f2) > 0)
    00195                                 p2 = *EVAL(p2) = f2 - list1 + list2;
    00196                         else
    00197                                 p2 = *EVAL(p2) = list2 + n*size;
    00198                 }
    00199         }
    00200 #else           /* pairwise merge only. */
    00201         for (f1 = list1, p2 = list2; f1 < last; f1 += size2) {
    00202                 p2 = *EVAL(p2) = p2 + size2;
    00203                 if (cmp (f1, f1 + size) > 0)
    00204                         swap(f1, f1 + size);
    00205         }
    00206 #endif /* NATURAL */
    00207 }
    00208
    00209 /*
    00210  * Arguments are as for qsort.
    00211  */
    00212 int
    00213 rpm_mergesort(void *base, size_t nmemb, size_t size,
    00214                 int (*cmp) (const void *, const void *))
    00215 {
    00216         register int i, sense;
    00217         int big, iflag;
    00218         register unsigned char *f1, *f2, *t, *b, *q, *l1, *l2;
    00219         /*@dependent@*/
    00220         register unsigned char *tp2;
    00221         /*@owned@*/
    00222         unsigned char *list2;
    00223         /*@dependent@*/
    00224         unsigned char *list1;
    00225         unsigned char *p2, *p, *last, **p1;
    00226
    00227         if (size < PSIZE / 2) {         /* Pointers must fit into 2 * size. */
    00228                 errno = EINVAL;
    00229                 return (-1);
    00230         }
    00231
    00232         if (nmemb == 0)
    00233                 return (0);
    00234
    00235         /*
    00236          * XXX
    00237          * Stupid subtraction for the Cray.
    00238          */
    00239         iflag = 0;
    00240         if (!(size % ISIZE) && !(((char *)base - (char *)0) % ISIZE))
    00241                 iflag = 1;
    00242
    00243         if ((list2 = malloc(nmemb * size + PSIZE)) == NULL)
    00244                 return (-1);
    00245
    00246         list1 = base;
    00247         setup(list1, list2, nmemb, size, cmp);
    00248         last = list2 + nmemb * size;
    00249         i = big = 0;
    00250         while (*EVAL(list2) != last) {
    00251             l2 = list1;
    00252             p1 = EVAL(list1);
    00253             for (tp2 = p2 = list2; p2 != last; p1 = EVAL(l2)) {
    00254                 p2 = *EVAL(p2);
    00255                 f1 = l2;
    00256                 f2 = l1 = list1 + (p2 - list2);
    00257                 if (p2 != last)
    00258                         p2 = *EVAL(p2);
    00259                 l2 = list1 + (p2 - list2);
    00260                 while (f1 < l1 && f2 < l2) {
    00261                         if ((*cmp)(f1, f2) <= 0) {
    00262                                 q = f2;
    00263                                 b = f1, t = l1;
    00264                                 sense = -1;
    00265                         } else {
    00266                                 q = f1;
    00267                                 b = f2, t = l2;
    00268                                 sense = 0;
    00269                         }
    00270                         if (!big) {     /* here i = 0 */
    00271                                 while ((b += size) < t && cmp(q, b) >sense)
    00272                                         if (++i == 6) {
    00273                                                 big = 1;
    00274                                                 goto EXPONENTIAL;
    00275                                         }
    00276                         } else {
    00277 /*@-shiftimplementation@*/
    00278 EXPONENTIAL:                    for (i = (int) size; ; i <<= 1)
    00279                                         if ((p = (b + i)) >= t) {
    00280                                                 if ((p = t - size) > b &&
    00281                                                     (*cmp)(q, p) <= sense)
    00282                                                         t = p;
    00283                                                 else
    00284                                                         b = p;
    00285                                                 /*@innerbreak@*/ break;
    00286                                         } else if ((*cmp)(q, p) <= sense) {
    00287                                                 t = p;
    00288                                                 if (i == (int) size)
    00289                                                         big = 0;
    00290                                                 goto FASTCASE;
    00291                                         } else
    00292                                                 b = p;
    00293                                 /*@-infloopsuncon@*/
    00294                                 while (t > b+size) {
    00295                                         i = (int) ((((t - b) / size) >> 1) * size);
    00296                                         if ((*cmp)(q, p = b + i) <= sense)
    00297                                                 t = p;
    00298                                         else
    00299                                                 b = p;
    00300                                 }
    00301                                 goto COPY;
    00302 FASTCASE:                       while (i > (int) size)
    00303                                         if ((*cmp)(q,
    00304                                                 p = b + (i >>= 1)) <= sense)
    00305                                                 t = p;
    00306                                         else
    00307                                                 b = p;
    00308                                 /*@=infloopsuncon@*/
    00309 /*@=shiftimplementation@*/
    00310 COPY:                           b = t;
    00311                         }
    00312                         i = (int) size;
    00313                         if (q == f1) {
    00314                                 if (iflag) {
    00315                                         ICOPY_LIST(f2, tp2, b);
    00316                                         ICOPY_ELT(f1, tp2, i);
    00317                                 } else {
    00318                                         CCOPY_LIST(f2, tp2, b);
    00319                                         CCOPY_ELT(f1, tp2, i);
    00320                                 }
    00321                         } else {
    00322                                 if (iflag) {
    00323                                         ICOPY_LIST(f1, tp2, b);
    00324                                         ICOPY_ELT(f2, tp2, i);
    00325                                 } else {
    00326                                         CCOPY_LIST(f1, tp2, b);
    00327                                         CCOPY_ELT(f2, tp2, i);
    00328                                 }
    00329                         }
    00330                 }
    00331                 if (f2 < l2) {
    00332                         if (iflag)
    00333                                 ICOPY_LIST(f2, tp2, l2);
    00334                         else
    00335                                 CCOPY_LIST(f2, tp2, l2);
    00336                 } else if (f1 < l1) {
    00337                         if (iflag)
    00338                                 ICOPY_LIST(f1, tp2, l1);
    00339                         else
    00340                                 CCOPY_LIST(f1, tp2, l1);
    00341                 }
    00342                 *p1 = l2;
    00343             }
    00344 /*@-dependenttrans@*/
    00345             tp2 = list1;        /* swap list1, list2 */
    00346             list1 = list2;
    00347             list2 = tp2;
    00348 /*@=dependenttrans@*/
    00349             last = list2 + nmemb*size;
    00350         }
    00351         if (base == list2) {
    00352                 memmove(list2, list1, nmemb*size);
    00353                 list2 = list1;
    00354         }
    00355 /*@-usereleased@*/
    00356         free(list2);
    00357 /*@=usereleased@*/
    00358         return (0);
    00359 }
    00360 /*@=mustmod =sizeoftype @*/