src/problems.c

   1 /*
   2  * Copyright (c) 2007-2009, Novell Inc.
   3  *
   4  * This program is licensed under the BSD license, read LICENSE.BSD
   5  * for further information
   6  */
   7
   8 /*
   9  * problems.c
  10  *
  11  */
  12
  13 #include <stdio.h>
  14 #include <stdlib.h>
  15 #include <unistd.h>
  16 #include <string.h>
  17 #include <assert.h>
  18
  19 #include "solver.h"
  20 #include "solver_private.h"
  21 #include "bitmap.h"
  22 #include "pool.h"
  23 #include "util.h"
  24 #include "evr.h"
  25 #include "solverdebug.h"
  26
  27
  28 /**********************************************************************************/
  29
  30 /* a problem is an item on the solver's problem list. It can either be >0, in that
  31  * case it is a update/infarch/dup rule, or it can be <0, which makes it refer to a job
  32  * consisting of multiple job rules.
  33  */
  34
  35 void
  36 solver_disableproblem(Solver *solv, Id v)
  37 {
  38   Rule *r;
  39   int i;
  40   Id *jp;
  41
  42   if (v > 0)
  43     {
  44       if (v >= solv->infarchrules && v < solv->infarchrules_end)
  45         {
  46           Pool *pool = solv->pool;
  47           Id name = pool->solvables[-solv->rules[v].p].name;
  48           while (v > solv->infarchrules && pool->solvables[-solv->rules[v - 1].p].name == name)
  49             v--;
  50           for (; v < solv->infarchrules_end && pool->solvables[-solv->rules[v].p].name == name; v++)
  51             solver_disablerule(solv, solv->rules + v);
  52           return;
  53         }
  54       if (v >= solv->duprules && v < solv->duprules_end)
  55         {
  56           Pool *pool = solv->pool;
  57           Id name = pool->solvables[-solv->rules[v].p].name;
  58           while (v > solv->duprules && pool->solvables[-solv->rules[v - 1].p].name == name)
  59             v--;
  60           for (; v < solv->duprules_end && pool->solvables[-solv->rules[v].p].name == name; v++)
  61             solver_disablerule(solv, solv->rules + v);
  62           return;
  63         }
  64       solver_disablerule(solv, solv->rules + v);
  65 #if 0
  66       /* XXX: doesn't work */
  67       if (v >= solv->updaterules && v < solv->updaterules_end)
  68         {
  69           /* enable feature rule if we disabled the update rule */
  70           r = solv->rules + (v - solv->updaterules + solv->featurerules);
  71           if (r->p)
  72             solver_enablerule(solv, r);
  73         }
  74 #endif
  75       return;
  76     }
  77   v = -(v + 1);
  78   jp = solv->ruletojob.elements;
  79   for (i = solv->jobrules, r = solv->rules + i; i < solv->jobrules_end; i++, r++, jp++)
  80     if (*jp == v)
  81       solver_disablerule(solv, r);
  82 }
  83
  84 /*-------------------------------------------------------------------
  85  * enableproblem
  86  */
  87
  88 void
  89 solver_enableproblem(Solver *solv, Id v)
  90 {
  91   Rule *r;
  92   int i;
  93   Id *jp;
  94
  95   if (v > 0)
  96     {
  97       if (v >= solv->infarchrules && v < solv->infarchrules_end)
  98         {
  99           Pool *pool = solv->pool;
 100           Id name = pool->solvables[-solv->rules[v].p].name;
 101           while (v > solv->infarchrules && pool->solvables[-solv->rules[v - 1].p].name == name)
 102             v--;
 103           for (; v < solv->infarchrules_end && pool->solvables[-solv->rules[v].p].name == name; v++)
 104             solver_enablerule(solv, solv->rules + v);
 105           return;
 106         }
 107       if (v >= solv->duprules && v < solv->duprules_end)
 108         {
 109           Pool *pool = solv->pool;
 110           Id name = pool->solvables[-solv->rules[v].p].name;
 111           while (v > solv->duprules && pool->solvables[-solv->rules[v - 1].p].name == name)
 112             v--;
 113           for (; v < solv->duprules_end && pool->solvables[-solv->rules[v].p].name == name; v++)
 114             solver_enablerule(solv, solv->rules + v);
 115           return;
 116         }
 117       if (v >= solv->featurerules && v < solv->featurerules_end)
 118         {
 119           /* do not enable feature rule if update rule is enabled */
 120           r = solv->rules + (v - solv->featurerules + solv->updaterules);
 121           if (r->d >= 0)
 122             return;
 123         }
 124       solver_enablerule(solv, solv->rules + v);
 125       if (v >= solv->updaterules && v < solv->updaterules_end)
 126         {
 127           /* disable feature rule when enabling update rule */
 128           r = solv->rules + (v - solv->updaterules + solv->featurerules);
 129           if (r->p)
 130             solver_disablerule(solv, r);
 131         }
 132       return;
 133     }
 134   v = -(v + 1);
 135   jp = solv->ruletojob.elements;
 136   for (i = solv->jobrules, r = solv->rules + i; i < solv->jobrules_end; i++, r++, jp++)
 137     if (*jp == v)
 138       solver_enablerule(solv, r);
 139 }
 140
 141
 142 /*-------------------------------------------------------------------
 143  * enable weak rules
 144  *
 145  * Reenable all disabled weak rules (marked in weakrulemap)
 146  *
 147  */
 148
 149 static void
 150 enableweakrules(Solver *solv)
 151 {
 152   int i;
 153   Rule *r;
 154
 155   for (i = 1, r = solv->rules + i; i < solv->learntrules; i++, r++)
 156     {
 157       if (r->d >= 0) /* already enabled? */
 158         continue;
 159       if (!MAPTST(&solv->weakrulemap, i))
 160         continue;
 161       solver_enablerule(solv, r);
 162     }
 163 }
 164
 165
 166 /*-------------------------------------------------------------------
 167  *
 168  * refine_suggestion
 169  *
 170  * at this point, all rules that led to conflicts are disabled.
 171  * we re-enable all rules of a problem set but rule "sug", then
 172  * continue to disable more rules until there as again a solution.
 173  */
 174
 175 /* FIXME: think about conflicting assertions */
 176
 177 static void
 178 refine_suggestion(Solver *solv, Id *problem, Id sug, Queue *refined, int essentialok)
 179 {
 180   Pool *pool = solv->pool;
 181   int i, j;
 182   Id v;
 183   Queue disabled;
 184   int disabledcnt;
 185
 186   IF_POOLDEBUG (SOLV_DEBUG_SOLUTIONS)
 187     {
 188       POOL_DEBUG(SOLV_DEBUG_SOLUTIONS, "refine_suggestion start\n");
 189       for (i = 0; problem[i]; i++)
 190         {
 191           if (problem[i] == sug)
 192             POOL_DEBUG(SOLV_DEBUG_SOLUTIONS, "=> ");
 193           solver_printproblem(solv, problem[i]);
 194         }
 195     }
 196   queue_empty(refined);
 197   if (!essentialok && sug < 0 && (solv->job.elements[-sug - 1] & SOLVER_ESSENTIAL) != 0)
 198     return;
 199   queue_init(&disabled);
 200   queue_push(refined, sug);
 201
 202   /* re-enable all problem rules with the exception of "sug"(gestion) */
 203   solver_reset(solv);
 204
 205   for (i = 0; problem[i]; i++)
 206     if (problem[i] != sug)
 207       solver_enableproblem(solv, problem[i]);
 208
 209   if (sug < 0)
 210     solver_reenablepolicyrules(solv, -sug);
 211   else if (sug >= solv->updaterules && sug < solv->updaterules_end)
 212     {
 213       /* enable feature rule */
 214       Rule *r = solv->rules + solv->featurerules + (sug - solv->updaterules);
 215       if (r->p)
 216         solver_enablerule(solv, r);
 217     }
 218
 219   enableweakrules(solv);
 220
 221   for (;;)
 222     {
 223       int njob, nfeature, nupdate, pass;
 224       queue_empty(&solv->problems);
 225       solver_reset(solv);
 226
 227       if (!solv->problems.count)
 228         solver_run_sat(solv, 0, 0);
 229
 230       if (!solv->problems.count)
 231         {
 232           POOL_DEBUG(SOLV_DEBUG_SOLUTIONS, "no more problems!\n");
 233           break;                /* great, no more problems */
 234         }
 235       disabledcnt = disabled.count;
 236       /* start with 1 to skip over proof index */
 237       njob = nfeature = nupdate = 0;
 238       for (pass = 0; pass < 2; pass++)
 239         {
 240           for (i = 1; i < solv->problems.count - 1; i++)
 241             {
 242               /* ignore solutions in refined */
 243               v = solv->problems.elements[i];
 244               if (v == 0)
 245                 break;  /* end of problem reached */
 246               if (sug != v)
 247                 {
 248                   /* check if v is in the given problems list
 249                    * we allow disabling all problem rules *after* sug in
 250                    * pass 2, to prevent getting the same solution twice */
 251                   for (j = 0; problem[j]; j++)
 252                     if (problem[j] == v || (pass && problem[j] == sug))
 253                       break;
 254                   if (problem[j] == v)
 255                     continue;
 256                 }
 257               if (v >= solv->featurerules && v < solv->featurerules_end)
 258                 nfeature++;
 259               else if (v > 0)
 260                 nupdate++;
 261               else
 262                 {
 263                   if (!essentialok && (solv->job.elements[-v -1] & SOLVER_ESSENTIAL) != 0)
 264                     continue;   /* not that one! */
 265                   njob++;
 266                 }
 267               queue_push(&disabled, v);
 268             }
 269           if (disabled.count != disabledcnt)
 270             break;
 271         }
 272       if (disabled.count == disabledcnt)
 273         {
 274           /* no solution found, this was an invalid suggestion! */
 275           POOL_DEBUG(SOLV_DEBUG_SOLUTIONS, "no solution found!\n");
 276           refined->count = 0;
 277           break;
 278         }
 279       if (!njob && nupdate && nfeature)
 280         {
 281           /* got only update rules, filter out feature rules */
 282           POOL_DEBUG(SOLV_DEBUG_SOLUTIONS, "throwing away feature rules\n");
 283           for (i = j = disabledcnt; i < disabled.count; i++)
 284             {
 285               v = disabled.elements[i];
 286               if (v < solv->featurerules || v >= solv->featurerules_end)
 287                 disabled.elements[j++] = v;
 288             }
 289           disabled.count = j;
 290           nfeature = 0;
 291         }
 292       if (disabled.count == disabledcnt + 1)
 293         {
 294           /* just one suggestion, add it to refined list */
 295           v = disabled.elements[disabledcnt];
 296           if (!nfeature)
 297             queue_push(refined, v);     /* do not record feature rules */
 298           solver_disableproblem(solv, v);
 299           if (v >= solv->updaterules && v < solv->updaterules_end)
 300             {
 301               Rule *r = solv->rules + (v - solv->updaterules + solv->featurerules);
 302               if (r->p)
 303                 solver_enablerule(solv, r);     /* enable corresponding feature rule */
 304             }
 305           if (v < 0)
 306             solver_reenablepolicyrules(solv, -v);
 307         }
 308       else
 309         {
 310           /* more than one solution, disable all */
 311           /* do not push anything on refine list, as we do not know which solution to choose */
 312           /* thus, the user will get another problem if he selects this solution, where he
 313            * can choose the right one */
 314           IF_POOLDEBUG (SOLV_DEBUG_SOLUTIONS)
 315             {
 316               POOL_DEBUG(SOLV_DEBUG_SOLUTIONS, "more than one solution found:\n");
 317               for (i = disabledcnt; i < disabled.count; i++)
 318                 solver_printproblem(solv, disabled.elements[i]);
 319             }
 320           for (i = disabledcnt; i < disabled.count; i++)
 321             {
 322               v = disabled.elements[i];
 323               solver_disableproblem(solv, v);
 324               if (v >= solv->updaterules && v < solv->updaterules_end)
 325                 {
 326                   Rule *r = solv->rules + (v - solv->updaterules + solv->featurerules);
 327                   if (r->p)
 328                     solver_enablerule(solv, r);
 329                 }
 330             }
 331         }
 332     }
 333   /* all done, get us back into the same state as before */
 334   /* enable refined rules again */
 335   for (i = 0; i < disabled.count; i++)
 336     solver_enableproblem(solv, disabled.elements[i]);
 337   queue_free(&disabled);
 338   /* reset policy rules */
 339   for (i = 0; problem[i]; i++)
 340     solver_enableproblem(solv, problem[i]);
 341   solver_disablepolicyrules(solv);
 342   /* disable problem rules again */
 343   for (i = 0; problem[i]; i++)
 344     solver_disableproblem(solv, problem[i]);
 345   POOL_DEBUG(SOLV_DEBUG_SOLUTIONS, "refine_suggestion end\n");
 346 }
 347
 348
 349 /*-------------------------------------------------------------------
 350  * sorting helper for problems
 351  *
 352  * bring update rules before job rules
 353  * make essential job rules last
 354  */
 355
 356 static int
 357 problems_sortcmp(const void *ap, const void *bp, void *dp)
 358 {
 359   Queue *job = dp;
 360   Id a = *(Id *)ap, b = *(Id *)bp;
 361   if (a < 0 && b > 0)
 362     return 1;
 363   if (a > 0 && b < 0)
 364     return -1;
 365   if (a < 0 && b < 0)
 366     {
 367       int af = job->elements[-a - 1] & SOLVER_ESSENTIAL;
 368       int bf = job->elements[-b - 1] & SOLVER_ESSENTIAL;
 369       int x = af - bf;
 370       if (x)
 371         return x;
 372     }
 373   return a - b;
 374 }
 375
 376 /*
 377  * convert a solution rule into a job modifier
 378  */
 379 static void
 380 convertsolution(Solver *solv, Id why, Queue *solutionq)
 381 {
 382   Pool *pool = solv->pool;
 383   if (why < 0)
 384     {
 385       queue_push(solutionq, 0);
 386       queue_push(solutionq, -why);
 387       return;
 388     }
 389   if (why >= solv->infarchrules && why < solv->infarchrules_end)
 390     {
 391       Id p, name;
 392       /* infarch rule, find replacement */
 393       assert(solv->rules[why].p < 0);
 394       name = pool->solvables[-solv->rules[why].p].name;
 395       while (why > solv->infarchrules && pool->solvables[-solv->rules[why - 1].p].name == name)
 396         why--;
 397       p = 0;
 398       for (; why < solv->infarchrules_end && pool->solvables[-solv->rules[why].p].name == name; why++)
 399         if (solv->decisionmap[-solv->rules[why].p] > 0)
 400           {
 401             p = -solv->rules[why].p;
 402             break;
 403           }
 404       if (!p)
 405         return;         /* false alarm */
 406       queue_push(solutionq, SOLVER_SOLUTION_INFARCH);
 407       queue_push(solutionq, p);
 408       return;
 409     }
 410   if (why >= solv->duprules && why < solv->duprules_end)
 411     {
 412       Id p, name;
 413       /* dist upgrade rule, find replacement */
 414       assert(solv->rules[why].p < 0);
 415       name = pool->solvables[-solv->rules[why].p].name;
 416       while (why > solv->duprules && pool->solvables[-solv->rules[why - 1].p].name == name)
 417         why--;
 418       p = 0;
 419       for (; why < solv->duprules_end && pool->solvables[-solv->rules[why].p].name == name; why++)
 420         if (solv->decisionmap[-solv->rules[why].p] > 0)
 421           {
 422             p = -solv->rules[why].p;
 423             break;
 424           }
 425       if (!p)
 426         return;         /* false alarm */
 427       queue_push(solutionq, SOLVER_SOLUTION_DISTUPGRADE);
 428       queue_push(solutionq, p);
 429       return;
 430     }
 431   if (why >= solv->updaterules && why < solv->updaterules_end)
 432     {
 433       /* update rule, find replacement package */
 434       Id p, *dp, rp = 0;
 435       Rule *rr;
 436
 437       assert(why >= solv->updaterules && why < solv->updaterules_end);
 438       /* check if this is a false positive, i.e. the update rule is fulfilled */
 439       rr = solv->rules + why;
 440       FOR_RULELITERALS(p, dp, rr)
 441         if (p > 0 && solv->decisionmap[p] > 0)
 442           break;
 443       if (p)
 444         return;         /* false alarm */
 445
 446       p = solv->installed->start + (why - solv->updaterules);
 447       rr = solv->rules + solv->featurerules + (why - solv->updaterules);
 448       if (!rr->p)
 449         rr = solv->rules + why;
 450       if (solv->dupmap_all && solv->rules[why].p != p && solv->decisionmap[p] > 0)
 451         {
 452           /* distupgrade case, allow to keep old package */
 453           queue_push(solutionq, SOLVER_SOLUTION_DISTUPGRADE);
 454           queue_push(solutionq, p);
 455           return;
 456         }
 457       if (solv->decisionmap[p] > 0)
 458         return;         /* false alarm, turned out we can keep the package */
 459       if (rr->w2)
 460         {
 461           int mvrp = 0;         /* multi-version replacement */
 462           FOR_RULELITERALS(rp, dp, rr)
 463             {
 464               if (rp > 0 && solv->decisionmap[rp] > 0 && pool->solvables[rp].repo != solv->installed)
 465                 {
 466                   mvrp = rp;
 467                   if (!(solv->noobsoletes.size && MAPTST(&solv->noobsoletes, rp)))
 468                     break;
 469                 }
 470             }
 471           if (!rp && mvrp)
 472             {
 473               /* found only multi-version replacements */
 474               /* have to split solution into two parts */
 475               queue_push(solutionq, p);
 476               queue_push(solutionq, mvrp);
 477             }
 478         }
 479       queue_push(solutionq, p);
 480       queue_push(solutionq, rp);
 481       return;
 482     }
 483 }
 484
 485 /*
 486  * convert problem data into a form usable for refining.
 487  * Returns the number of problems.
 488  */
 489 int
 490 solver_prepare_solutions(Solver *solv)
 491 {
 492   int i, j = 1, idx;
 493
 494   if (!solv->problems.count)
 495     return 0;
 496   queue_empty(&solv->solutions);
 497   queue_push(&solv->solutions, 0);      /* dummy so idx is always nonzero */
 498   idx = solv->solutions.count;
 499   queue_push(&solv->solutions, -1);     /* unrefined */
 500   /* proofidx stays in position, thus we start with 1 */
 501   for (i = 1; i < solv->problems.count; i++)
 502     {
 503       Id p = solv->problems.elements[i];
 504       queue_push(&solv->solutions, p);
 505       if (p)
 506         continue;
 507       /* end of problem reached */
 508       solv->problems.elements[j++] = idx;
 509       if (i + 1 >= solv->problems.count)
 510         break;
 511       /* start another problem */
 512       solv->problems.elements[j++] = solv->problems.elements[++i];  /* copy proofidx */
 513       idx = solv->solutions.count;
 514       queue_push(&solv->solutions, -1); /* unrefined */
 515     }
 516   solv->problems.count = j;
 517   return j / 2;
 518 }
 519
 520 /*
 521  * refine the simple solution rule list provided by
 522  * the solver into multiple lists of job modifiers.
 523  */
 524 static void
 525 create_solutions(Solver *solv, int probnr, int solidx)
 526 {
 527   Pool *pool = solv->pool;
 528   Queue redoq;
 529   Queue problem, solution, problems_save;
 530   int i, j, nsol;
 531   int essentialok;
 532   unsigned int now;
 533   int oldmistakes = solv->cleandeps_mistakes ? solv->cleandeps_mistakes->count : 0;
 534
 535   now = solv_timems(0);
 536   queue_init(&redoq);
 537   /* save decisionq, decisionq_why, decisionmap */
 538   for (i = 0; i < solv->decisionq.count; i++)
 539     {
 540       Id p = solv->decisionq.elements[i];
 541       queue_push(&redoq, p);
 542       queue_push(&redoq, solv->decisionq_why.elements[i]);
 543       queue_push(&redoq, solv->decisionmap[p > 0 ? p : -p]);
 544     }
 545   /* save problems queue */
 546   problems_save = solv->problems;
 547   memset(&solv->problems, 0, sizeof(solv->problems));
 548
 549   /* extract problem from queue */
 550   queue_init(&problem);
 551   for (i = solidx + 1; i < solv->solutions.count; i++)
 552     {
 553       Id v = solv->solutions.elements[i];
 554       if (!v)
 555         break;
 556       queue_push(&problem, v);
 557     }
 558   if (problem.count > 1)
 559     solv_sort(problem.elements, problem.count, sizeof(Id), problems_sortcmp, &solv->job);
 560   queue_push(&problem, 0);      /* mark end for refine_suggestion */
 561   problem.count--;
 562 #if 0
 563   for (i = 0; i < problem.count; i++)
 564     printf("PP %d %d\n", i, problem.elements[i]);
 565 #endif
 566
 567   /* refine each solution element */
 568   nsol = 0;
 569   essentialok = 0;
 570   queue_init(&solution);
 571   for (i = 0; i < problem.count; i++)
 572     {
 573       int solstart = solv->solutions.count;
 574       refine_suggestion(solv, problem.elements, problem.elements[i], &solution, essentialok);
 575       queue_push(&solv->solutions, 0);  /* reserve room for number of elements */
 576       for (j = 0; j < solution.count; j++)
 577         convertsolution(solv, solution.elements[j], &solv->solutions);
 578       if (solv->solutions.count == solstart + 1)
 579         {
 580           solv->solutions.count--;      /* this one did not work out */
 581           if (nsol || i + 1 < problem.count)
 582             continue;                   /* got one or still hope */
 583           if (!essentialok)
 584             {
 585               /* nothing found, start over */
 586               POOL_DEBUG(SOLV_DEBUG_SOLUTIONS, "nothing found, re-run with essentialok = 1\n");
 587               essentialok = 1;
 588               i = -1;
 589               continue;
 590             }
 591           /* this is bad, we found no solution */
 592           /* for now just offer a rule */
 593           POOL_DEBUG(SOLV_DEBUG_SOLUTIONS, "nothing found, already did essentialok, fake it\n");
 594           queue_push(&solv->solutions, 0);
 595           for (j = 0; j < problem.count; j++)
 596             {
 597               convertsolution(solv, problem.elements[j], &solv->solutions);
 598               if (solv->solutions.count > solstart + 1)
 599                 break;
 600             }
 601           if (solv->solutions.count == solstart + 1)
 602             {
 603               solv->solutions.count--;
 604               continue;         /* sorry */
 605             }
 606         }
 607       /* patch in number of solution elements */
 608       solv->solutions.elements[solstart] = (solv->solutions.count - (solstart + 1)) / 2;
 609       queue_push(&solv->solutions, 0);  /* add end marker */
 610       queue_push(&solv->solutions, 0);  /* add end marker */
 611       solv->solutions.elements[solidx + 1 + nsol++] = solstart;
 612     }
 613   solv->solutions.elements[solidx + 1 + nsol] = 0;      /* end marker */
 614   solv->solutions.elements[solidx] = nsol;
 615   queue_free(&problem);
 616   queue_free(&solution);
 617
 618   /* restore decisions */
 619   memset(solv->decisionmap, 0, pool->nsolvables * sizeof(Id));
 620   queue_empty(&solv->decisionq);
 621   queue_empty(&solv->decisionq_why);
 622   for (i = 0; i < redoq.count; i += 3)
 623     {
 624       Id p = redoq.elements[i];
 625       queue_push(&solv->decisionq, p);
 626       queue_push(&solv->decisionq_why, redoq.elements[i + 1]);
 627       solv->decisionmap[p > 0 ? p : -p] = redoq.elements[i + 2];
 628     }
 629   queue_free(&redoq);
 630   /* restore problems */
 631   queue_free(&solv->problems);
 632   solv->problems = problems_save;
 633
 634   if (solv->cleandeps_mistakes)
 635     {
 636       if (oldmistakes)
 637         queue_truncate(solv->cleandeps_mistakes, oldmistakes);
 638       else
 639         {
 640           queue_free(solv->cleandeps_mistakes);
 641           solv->cleandeps_mistakes = solv_free(solv->cleandeps_mistakes);
 642         }
 643     }
 644
 645   POOL_DEBUG(SOLV_DEBUG_STATS, "create_solutions for problem #%d took %d ms\n", probnr, solv_timems(now));
 646 }
 647
 648
 649 /**************************************************************************/
 650
 651 unsigned int
 652 solver_problem_count(Solver *solv)
 653 {
 654   return solv->problems.count / 2;
 655 }
 656
 657 Id
 658 solver_next_problem(Solver *solv, Id problem)
 659 {
 660   if (!problem)
 661     return solv->problems.count ? 1 : 0;
 662   return (problem + 1) * 2 - 1 < solv->problems.count ? problem + 1 : 0;
 663 }
 664
 665 unsigned int
 666 solver_solution_count(Solver *solv, Id problem)
 667 {
 668   Id solidx = solv->problems.elements[problem * 2 - 1];
 669   if (solv->solutions.elements[solidx] < 0)
 670     create_solutions(solv, problem, solidx);
 671   return solv->solutions.elements[solidx];
 672 }
 673
 674 Id
 675 solver_next_solution(Solver *solv, Id problem, Id solution)
 676 {
 677   Id solidx = solv->problems.elements[problem * 2 - 1];
 678   if (solv->solutions.elements[solidx] < 0)
 679     create_solutions(solv, problem, solidx);
 680   return solv->solutions.elements[solidx + solution + 1] ? solution + 1 : 0;
 681 }
 682
 683 unsigned int
 684 solver_solutionelement_count(Solver *solv, Id problem, Id solution)
 685 {
 686   Id solidx = solv->problems.elements[problem * 2 - 1];
 687   solidx = solv->solutions.elements[solidx + solution];
 688   return solv->solutions.elements[solidx];
 689 }
 690
 691
 692 /*
 693  *  return the next item of the proposed solution
 694  *  here are the possibilities for p / rp and what
 695  *  the solver expects the application to do:
 696  *    p                             rp
 697  *  -------------------------------------------------------
 698  *    SOLVER_SOLUTION_INFARCH       pkgid
 699  *    -> add (SOLVER_INSTALL|SOLVER_SOLVABLE, rp) to the job
 700  *    SOLVER_SOLUTION_DISTUPGRADE   pkgid
 701  *    -> add (SOLVER_INSTALL|SOLVER_SOLVABLE, rp) to the job
 702  *    SOLVER_SOLUTION_JOB           jobidx
 703  *    -> remove job (jobidx - 1, jobidx) from job queue
 704  *    pkgid (> 0)                   0
 705  *    -> add (SOLVER_ERASE|SOLVER_SOLVABLE, p) to the job
 706  *    pkgid (> 0)                   pkgid (> 0)
 707  *    -> add (SOLVER_INSTALL|SOLVER_SOLVABLE, rp) to the job
 708  *       (this will replace package p)
 709  *
 710  * Thus, the solver will either ask the application to remove
 711  * a specific job from the job queue, or ask to add an install/erase
 712  * job to it.
 713  *
 714  */
 715
 716 Id
 717 solver_next_solutionelement(Solver *solv, Id problem, Id solution, Id element, Id *p, Id *rp)
 718 {
 719   Id solidx = solv->problems.elements[problem * 2 - 1];
 720   solidx = solv->solutions.elements[solidx + solution];
 721   if (!solidx)
 722     return 0;
 723   solidx += 1 + element * 2;
 724   if (!solv->solutions.elements[solidx] && !solv->solutions.elements[solidx + 1])
 725     return 0;
 726   *p = solv->solutions.elements[solidx];
 727   *rp = solv->solutions.elements[solidx + 1];
 728   return element + 1;
 729 }
 730
 731 void
 732 solver_take_solutionelement(Solver *solv, Id p, Id rp, Queue *job)
 733 {
 734   int i;
 735
 736   if (p == SOLVER_SOLUTION_JOB)
 737     {
 738       job->elements[rp - 1] = SOLVER_NOOP;
 739       job->elements[rp] = 0;
 740       return;
 741     }
 742   if (rp <= 0 && p <= 0)
 743     return;     /* just in case */
 744   if (rp > 0)
 745     p = SOLVER_INSTALL|SOLVER_SOLVABLE;
 746   else
 747     {
 748       rp = p;
 749       p = SOLVER_ERASE|SOLVER_SOLVABLE;
 750     }
 751   for (i = 0; i < job->count; i += 2)
 752     if (job->elements[i] == p && job->elements[i + 1] == rp)
 753       return;
 754   queue_push2(job, p, rp);
 755 }
 756
 757 void
 758 solver_take_solution(Solver *solv, Id problem, Id solution, Queue *job)
 759 {
 760   Id p, rp, element = 0;
 761   while ((element = solver_next_solutionelement(solv, problem, solution, element, &p, &rp)) != 0)
 762     solver_take_solutionelement(solv, p, rp, job);
 763 }
 764
 765
 766 /*-------------------------------------------------------------------
 767  *
 768  * find problem rule
 769  */
 770
 771 static void
 772 findproblemrule_internal(Solver *solv, Id idx, Id *reqrp, Id *conrp, Id *sysrp, Id *jobrp)
 773 {
 774   Id rid, d;
 775   Id lreqr, lconr, lsysr, ljobr;
 776   Rule *r;
 777   Id jobassert = 0;
 778   int i, reqset = 0;    /* 0: unset, 1: installed, 2: jobassert, 3: assert */
 779
 780   /* find us a jobassert rule */
 781   for (i = idx; (rid = solv->learnt_pool.elements[i]) != 0; i++)
 782     {
 783       if (rid < solv->jobrules || rid >= solv->jobrules_end)
 784         continue;
 785       r = solv->rules + rid;
 786       d = r->d < 0 ? -r->d - 1 : r->d;
 787       if (!d && r->w2 == 0 && r->p > 0)
 788         {
 789           jobassert = r->p;
 790           break;
 791         }
 792     }
 793
 794   /* the problem rules are somewhat ordered from "near to the problem" to
 795    * "near to the job" */
 796   lreqr = lconr = lsysr = ljobr = 0;
 797   while ((rid = solv->learnt_pool.elements[idx++]) != 0)
 798     {
 799       assert(rid > 0);
 800       if (rid >= solv->learntrules)
 801         findproblemrule_internal(solv, solv->learnt_why.elements[rid - solv->learntrules], &lreqr, &lconr, &lsysr, &ljobr);
 802       else if ((rid >= solv->jobrules && rid < solv->jobrules_end) || (rid >= solv->infarchrules && rid < solv->infarchrules_end) || (rid >= solv->duprules && rid < solv->duprules_end))
 803         {
 804           if (!*jobrp)
 805             *jobrp = rid;
 806         }
 807       else if (rid >= solv->updaterules && rid < solv->updaterules_end)
 808         {
 809           if (!*sysrp)
 810             *sysrp = rid;
 811         }
 812       else
 813         {
 814           assert(rid < solv->rpmrules_end);
 815           r = solv->rules + rid;
 816           d = r->d < 0 ? -r->d - 1 : r->d;
 817           if (!d && r->w2 < 0)
 818             {
 819               if (!*conrp)
 820                 *conrp = rid;
 821             }
 822           else
 823             {
 824               if (!d && r->w2 == 0 && reqset < 3)
 825                 {
 826                   if (*reqrp > 0 && r->p < -1)
 827                     {
 828                       Id op = -solv->rules[*reqrp].p;
 829                       if (op > 1 && solv->pool->solvables[op].arch != solv->pool->solvables[-r->p].arch)
 830                         continue;       /* different arch, skip */
 831                     }
 832                   /* prefer assertions */
 833                   *reqrp = rid;
 834                   reqset = 3;
 835                 }
 836               else if (jobassert && r->p == -jobassert)
 837                 {
 838                   /* prefer rules of job assertions */
 839                   *reqrp = rid;
 840                   reqset = 2;
 841                 }
 842               else if (solv->installed && r->p < 0 && solv->pool->solvables[-r->p].repo == solv->installed && reqset <= 1)
 843                 {
 844                   /* prefer rules of job installed package so that the user doesn't get confused by strange packages */
 845                   *reqrp = rid;
 846                   reqset = 1;
 847                 }
 848               else if (!*reqrp)
 849                 *reqrp = rid;
 850             }
 851         }
 852     }
 853   if (!*reqrp && lreqr)
 854     *reqrp = lreqr;
 855   if (!*conrp && lconr)
 856     *conrp = lconr;
 857   if (!*jobrp && ljobr)
 858     *jobrp = ljobr;
 859   if (!*sysrp && lsysr)
 860     *sysrp = lsysr;
 861 }
 862
 863 /*
 864  * find problem rule
 865  *
 866  * search for a rule that describes the problem to the
 867  * user. Actually a pretty hopeless task that may leave the user
 868  * puzzled. To get all of the needed information use
 869  * solver_findallproblemrules() instead.
 870  */
 871
 872 Id
 873 solver_findproblemrule(Solver *solv, Id problem)
 874 {
 875   Id reqr, conr, sysr, jobr;
 876   Id idx = solv->problems.elements[2 * problem - 2];
 877   reqr = conr = sysr = jobr = 0;
 878   findproblemrule_internal(solv, idx, &reqr, &conr, &sysr, &jobr);
 879   if (reqr)
 880     return reqr;        /* some requires */
 881   if (conr)
 882     return conr;        /* some conflict */
 883   if (sysr)
 884     return sysr;        /* an update rule */
 885   if (jobr)
 886     return jobr;        /* a user request */
 887   assert(0);
 888   return 0;
 889 }
 890
 891 /*-------------------------------------------------------------------*/
 892
 893 static void
 894 findallproblemrules_internal(Solver *solv, Id idx, Queue *rules)
 895 {
 896   Id rid;
 897   while ((rid = solv->learnt_pool.elements[idx++]) != 0)
 898     {
 899       if (rid >= solv->learntrules)
 900         {
 901           findallproblemrules_internal(solv, solv->learnt_why.elements[rid - solv->learntrules], rules);
 902           continue;
 903         }
 904       queue_pushunique(rules, rid);
 905     }
 906 }
 907
 908 /*
 909  * find all problem rule
 910  *
 911  * return all rules that lead to the problem. This gives the user
 912  * all of the information to understand the problem, but the result
 913  * can be a large number of rules.
 914  */
 915
 916 void
 917 solver_findallproblemrules(Solver *solv, Id problem, Queue *rules)
 918 {
 919   queue_empty(rules);
 920   findallproblemrules_internal(solv, solv->problems.elements[2 * problem - 2], rules);
 921 }
 922
 923 /* EOF */