Performance improvement in PropXPlusYEqZ

CHANGES.md

@@ -14,6 +14,7 @@ NEXT MILESTONE
 ### Other closed issues and pull requests:
 See [milestone 5.0.0-beta.2](https://github.com/chocoteam/choco-solver/milestone/41)
 
+- Performance improvement in PropXPlusYEqZ and PropAbsolute
 - Fix bug in ConflictOrderingSearch (monitor not plugged)
 - Performance improvement for LastConflict, ConflictOrderingSearch and StrategySequencer.
 - Fix bug : regular constraints parsed from XCSP now support negative values

solver/src/main/java/org/chocosolver/solver/constraints/binary/PropAbsolute.java

@@ -38,7 +38,7 @@ public PropAbsolute(IntVar X, IntVar Y) {
         super(ArrayUtils.toArray(X, Y), PropagatorPriority.BINARY, true);
         this.X = vars[0];
         this.Y = vars[1];
-        bothEnumerated = X.hasEnumeratedDomain() && Y.hasEnumeratedDomain();
+        bothEnumerated = X.hasUnfixedEnumeratedDomain() && Y.hasUnfixedEnumeratedDomain();
     }
 
     @Override
@@ -101,8 +101,8 @@ public void propagate(int varIdx, int mask) throws ContradictionException {
                 Y.updateLowerBound(-val, this, lcg() ? Reason.r(X.getValLit()) : Reason.undef());
                 Y.updateUpperBound(val, this, lcg() ? Reason.r(X.getValLit()) : Reason.undef());
                 val--;
-                for (int v = -val; v <= val; v = Y.nextValue(v)) {
-                    Y.removeValue(v, this, lcg() ? Reason.r(X.getValLit()) : Reason.undef());
+                if (val >= 0) {
+                    removeInterval(Y, -val, val, lcg() ? Reason.r(X.getValLit()) : Reason.undef());
                 }
                 setPassive();
             } else {
@@ -124,10 +124,9 @@ private void setBounds() throws ContradictionException {
         int min = X.getLB();
         Y.updateLowerBound(-max, this, lcg() ? Reason.r(X.getMaxLit()) : Reason.undef());
         Y.updateUpperBound(max, this, lcg() ? Reason.r(X.getMaxLit()) : Reason.undef());
-        for (int v = 1 - min; v <= min - 1; v = Y.nextValue(v)) {
-            Y.removeValue(v, this, lcg() ? Reason.r(X.getMinLit()) : Reason.undef());
+        if (1 - min <= min -1) {
+            removeInterval(Y, 1 - min, min - 1, lcg() ? Reason.r(X.getMinLit()) : Reason.undef());
         }
-        //if (!lcg()) Y.removeInterval(1 - min, min - 1, this);
         /////////////////////////////////////////////////
         int prevLB = X.getLB();
         int prevUB = X.getUB();
@@ -178,4 +177,13 @@ private void enumeratedFiltering() throws ContradictionException {
     // EXPLANATIONS
     //***********************************************************************************
 
+    private void removeInterval(IntVar intVar, int fromIncl, int toIncl, Reason reason) throws ContradictionException {
+        if (!lcg()) {
+            intVar.removeInterval(fromIncl, toIncl, this);
+        } else {
+            for (int i=fromIncl; i<=toIncl; i++) {
+                intVar.removeValue(i, this, reason);
+            }
+        }
+    }
 }

solver/src/main/java/org/chocosolver/solver/constraints/ternary/PropXplusYeqZ.java

@@ -18,6 +18,8 @@
 import org.chocosolver.util.ESat;
 import org.chocosolver.util.objects.setDataStructures.iterable.IntIterableRangeSet;
 
+import java.util.Arrays;
+
 /**
  * A propagator to ensure that X + Y = Z holds, where X, Y and Z are IntVar.
  * This propagator ensures AC when all variables are enumerated, BC otherwise.
@@ -32,9 +34,10 @@ public class PropXplusYeqZ extends Propagator<IntVar> {
 
     private static final int THRESHOLD = 300;
     /**
-     * Set to <tt>true</tt> if X, Y and Z are bounded
+     * Set to <tt>true</tt> if at least two variables from X, Y and Z are either fixed or bounded
+     * Or if LCG is used, as AC is not explained yet
      */
-    private final boolean allbounded;
+    private final boolean isRangeOnly;
     /**
      * Temporary structure to ease filtering
      */
@@ -49,7 +52,9 @@ public class PropXplusYeqZ extends Propagator<IntVar> {
      */
     public PropXplusYeqZ(IntVar X, IntVar Y, IntVar Z) {
         super(new IntVar[]{X, Y, Z}, PropagatorPriority.TERNARY, false);
-        allbounded = (!X.hasEnumeratedDomain() & !Y.hasEnumeratedDomain() & !Z.hasEnumeratedDomain());
+        isRangeOnly = lcg() || Arrays.stream(vars)
+                .filter(v -> !v.hasUnfixedEnumeratedDomain())
+                .count() >= 2;
         set = new IntIterableRangeSet();
     }
 
@@ -77,8 +82,7 @@ private boolean filterPlus() throws ContradictionException {
                 lcg() ? Reason.r(vars[0].getMinLit(), vars[1].getMinLit()) : Reason.undef());
         change |= vars[2].updateUpperBound(ub, this,
                 lcg() ? Reason.r(vars[0].getMaxLit(), vars[1].getMaxLit()) : Reason.undef());
-        if (!allbounded) {
-            if ((long) vars[0].getDomainSize() * vars[1].getDomainSize() > THRESHOLD || lcg()) return change;
+        if (isAC(vars[0], vars[1])) {
             set.clear();
             int ub1 = vars[0].getUB();
             int ub2 = vars[1].getUB();
@@ -115,8 +119,7 @@ private boolean filterMinus(int vr) throws ContradictionException {
                 lcg() ? Reason.r(vars[2].getMinLit(), vars[vo].getMaxLit()) : Reason.undef());
         change |= vars[vr].updateUpperBound(ub, this,
                 lcg() ? Reason.r(vars[2].getMaxLit(), vars[vo].getMinLit()) : Reason.undef());
-        if (!allbounded) {
-            if ((long) vars[2].getDomainSize() * vars[vo].getDomainSize() > THRESHOLD || lcg()) return change;
+        if (isAC(vars[2], vars[vo])) {
             set.clear();
             int ub1 = vars[2].getUB();
             int ub2 = vars[vo].getUB();
@@ -138,6 +141,10 @@ private boolean filterMinus(int vr) throws ContradictionException {
         return change;
     }
 
+    private boolean isAC(IntVar v1, IntVar v2) {
+        return !isRangeOnly && (long) v1.getDomainSize() * v2.getDomainSize() < THRESHOLD;
+    }
+
     @Override
     public ESat isEntailed() {
         int sumUB = 0, sumLB = 0, i = 0;

solver/src/main/java/org/chocosolver/solver/variables/IntVar.java

@@ -761,6 +761,14 @@ default int getRange(){
      */
     boolean hasEnumeratedDomain();
 
+    /**
+     * Indicates wether (or not) <code>this</code> has an enumerated domain (represented in extension) and is not a single value
+     * @return <code>true</code> if the domain is enumerated and the variable is not instantiated yet, <code>false</code> otherwise.
+     */
+    default boolean hasUnfixedEnumeratedDomain() {
+        return !isInstantiated() && hasEnumeratedDomain();
+    }
+
     /**
      * Allow to monitor removed values of <code>this</code>.
      *