- more comments

[platform/upstream/libsolv.git] / src / solver.c

diff --git a/src/solver.c b/src/solver.c
index f858db8..5d2c162 100644 (file)
--- a/src/solver.c
+++ b/src/solver.c
@@ -1557,6 +1557,9 @@ addwatches_rule(Solver *solv, Rule *r)
  * Evaluate each term affected by the decision (linked through watches)
  * If we find unit rules we make new decisions based on them
  * 
+ * Everything's fixed there, it's just finding rules that are
+ * unit.
+ * 
  * return : 0 = everything is OK
  *          rule = conflict found in this rule
  */
@@ -1610,9 +1613,10 @@ propagate(Solver *solv, int level)
              solver_printrule(solv, SAT_DEBUG_PROPAGATE, r);
            }
 
-           /* 'pkg' was just decided
-            *   now find other literal watch, check clause
-            *  and advance on linked list
+           /* 'pkg' was just decided (was set to FALSE)
+            * 
+            *  now find other literal watch, check clause
+            *   and advance on linked list
             */
          if (pkg == r->w1)
            {
@@ -1634,27 +1638,36 @@ propagate(Solver *solv, int level)
 
            /*
             * The other literal is FALSE or UNDEF
+            * 
             */
            
           if (r->d)
            {
-             /* not a binary clause, try to move our watch.
-              * search for a literal that is not other_watch and not FALSE
+             /* Not a binary clause, try to move our watch.
+              * 
+              * Go over all literals and find one that is
+              *   not other_watch
+              *   and not FALSE
+              * 
               * (TRUE is also ok, in that case the rule is fulfilled)
               */
              if (r->p                                /* we have a 'p' */
-                 && r->p != other_watch              /* which is watched */
+                 && r->p != other_watch              /* which is not watched */
                  && !DECISIONMAP_FALSE(r->p))        /* and not FALSE */
                {
                  p = r->p;
                }
              else                                    /* go find a 'd' to make 'true' */
                {
-                 /* foreach 'd' */
+                 /* foreach p in 'd'
+                    we just iterate sequentially, doing it in another order just changes the order of decisions, not the decisions itself
+                  */
                  for (dp = pool->whatprovidesdata + r->d; (p = *dp++) != 0;)
-                   if (p != other_watch              /* which is not watched */
-                       && !DECISIONMAP_FALSE(p))     /* and not FALSE */
-                     break;
+                   {
+                     if (p != other_watch              /* which is not watched */
+                         && !DECISIONMAP_FALSE(p))     /* and not FALSE */
+                       break;
+                   }
                }
 
              if (p)
@@ -3889,13 +3902,15 @@ solver_solve(Solver *solv, Queue *job)
   solv->featurerules = solv->nrules;              /* mark start of feature rules */
   if (installed)
     {
-       /* foreach installed solvable */
+       /* foreach possibly installed solvable */
       for (i = installed->start, s = pool->solvables + i; i < installed->end; i++, s++)
        {
-           /*
-            * patterns use this
-            */
-
+         if (s->repo != installed)
+           {
+             addrule(solv, 0, 0);      /* create dummy rule */
+             continue;
+           }
+#if CODE10
          if (s->freshens && !s->supplements)
            {
              const char *name = id2str(pool, s->name);
@@ -3905,12 +3920,7 @@ solver_solve(Solver *solv, Queue *job)
                  continue;
                }
            }
-
-         if (s->repo != installed)
-           {
-             addrule(solv, 0, 0);      /* create dummy rule */
-             continue;
-           }
+#endif
          addupdaterule(solv, s, 1);    /* allow s to be updated */
        }
        /*
@@ -3931,6 +3941,7 @@ solver_solve(Solver *solv, Queue *job)
     
   POOL_DEBUG(SAT_DEBUG_SCHUBI, "*** Add update rules ***\n");
   solv->updaterules = solv->nrules;
+
   if (installed)
     { /* foreach installed solvables */
       /* we create all update rules, but disable some later on depending on the job */
@@ -3938,6 +3949,12 @@ solver_solve(Solver *solv, Queue *job)
        {
          Rule *sr;
 
+         if (s->repo != installed)
+           {
+             addrule(solv, 0, 0);      /* create dummy rule */
+             continue;
+           }
+
 #if CODE10
          /* no update rules for patch atoms */
          if (s->freshens && !s->supplements)
@@ -3950,13 +3967,8 @@ solver_solve(Solver *solv, Queue *job)
                }
            }
 #endif
-         if (s->repo != installed)
-           {
-             addrule(solv, 0, 0);      /* create dummy rule */
-             continue;
-           }
          addupdaterule(solv, s, 0);    /* allowall = 0: downgrades allowed */
-           
+
            /*
             * check for and remove duplicate
             */