make clear seperation

src/tree/updater_distcol-inl.hpp

@@ -32,13 +32,13 @@ class DistColMaker : public ColMaker<TStats> {
     utils::Check(trees.size() == 1, "DistColMaker: only support one tree at a time");
     // build the tree
     builder.Update(gpair, p_fmat, info, trees[0]);
-    // prune the tree
+    //// prune the tree
     pruner.Update(gpair, p_fmat, info, trees);
     this->SyncTrees(trees[0]);
     // update position after the tree is pruned
     builder.UpdatePosition(p_fmat, *trees[0]);
   }
-
+  
  private:
   inline void SyncTrees(RegTree *tree) {
     std::string s_model;
@@ -63,10 +63,12 @@ class DistColMaker : public ColMaker<TStats> {
       #pragma omp parallel for schedule(static)
       for (bst_omp_uint i = 0; i < ndata; ++i) {
         const bst_uint ridx = rowset[i];
-        int nid = this->position[ridx];
-        if (nid < 0) {
-          
+        int nid = this->DecodePosition(ridx);
+        while (tree[nid].is_deleted()) {
+          nid = tree[nid].parent();
+          utils::Assert(nid >=0, "distributed learning error");
         }
+        this->position[ridx] = nid;
       }
     }
    protected:    
@@ -111,6 +113,7 @@ class DistColMaker : public ColMaker<TStats> {
           }
         }
       }
+
       // communicate bitmap
       sync::AllReduce(BeginPtr(bitmap.data), bitmap.data.size(), sync::kBitwiseOR);
       const std::vector<bst_uint> &rowset = p_fmat->buffered_rowset();
@@ -125,7 +128,7 @@ class DistColMaker : public ColMaker<TStats> {
           if (tree[nid].default_left()) {
             this->SetEncodePosition(ridx, tree[nid].cright());
           } else {
-            this->SetEncodePosition(ridx, tree[nid].cright());
+            this->SetEncodePosition(ridx, tree[nid].cleft());
           }
         }
       }