Use `UpdateAllowUnknown' for non-model related parameter. (#4961)

* Use `UpdateAllowUnknown' for non-model related parameter.

Model parameter can not pack an additional boolean value due to binary IO
format.  This commit deals only with non-model related parameter configuration.

* Add tidy command line arg for use-dmlc-gtest.

include/xgboost/base.h

@@ -225,7 +225,7 @@ using GradientPairInteger = detail::GradientPairInternal<int64_t>;
 using Args = std::vector<std::pair<std::string, std::string> >;
 
 /*! \brief small eps gap for minimum split decision. */
-const bst_float kRtEps = 1e-6f;
+constexpr bst_float kRtEps = 1e-6f;
 
 /*! \brief define unsigned long for openmp loop */
 using omp_ulong = dmlc::omp_ulong;  // NOLINT

include/xgboost/generic_parameters.h

@@ -5,14 +5,13 @@
 #ifndef XGBOOST_GENERIC_PARAMETERS_H_
 #define XGBOOST_GENERIC_PARAMETERS_H_
 
-#include <dmlc/parameter.h>
 #include <xgboost/logging.h>
 #include <xgboost/parameter.h>
 
 #include <string>
 
 namespace xgboost {
-struct GenericParameter : public dmlc::Parameter<GenericParameter> {
+struct GenericParameter : public XGBoostParameter<GenericParameter> {
   // stored random seed
   int seed;
   // whether seed the PRNG each iteration

include/xgboost/json.h

@@ -5,6 +5,7 @@
 #define XGBOOST_JSON_H_
 
 #include <xgboost/logging.h>
+#include <xgboost/parameter.h>
 #include <string>
 
 #include <map>
@@ -533,7 +534,7 @@ using Null    = JsonNull;
 // Utils tailored for XGBoost.
 
 template <typename Type>
-Object toJson(dmlc::Parameter<Type> const& param) {
+Object toJson(XGBoostParameter<Type> const& param) {
   Object obj;
   for (auto const& kv : param.__DICT__()) {
     obj[kv.first] = kv.second;
@@ -542,13 +543,13 @@ Object toJson(dmlc::Parameter<Type> const& param) {
 }
 
 template <typename Type>
-void fromJson(Json const& obj, dmlc::Parameter<Type>* param) {
+void fromJson(Json const& obj, XGBoostParameter<Type>* param) {
   auto const& j_param = get<Object const>(obj);
   std::map<std::string, std::string> m;
   for (auto const& kv : j_param) {
     m[kv.first] = get<String const>(kv.second);
   }
-  param->InitAllowUnknown(m);
+  param->UpdateAllowUnknown(m);
 }
 }  // namespace xgboost
 #endif  // XGBOOST_JSON_H_

include/xgboost/logging.h

@@ -9,9 +9,10 @@
 #define XGBOOST_LOGGING_H_
 
 #include <dmlc/logging.h>
-#include <dmlc/parameter.h>
 #include <dmlc/thread_local.h>
+
 #include <xgboost/base.h>
+#include <xgboost/parameter.h>
 
 #include <sstream>
 #include <map>
@@ -35,7 +36,7 @@ class BaseLogger {
 };
 
 // Parsing both silent and debug_verbose is to provide backward compatibility.
-struct ConsoleLoggerParam : public dmlc::Parameter<ConsoleLoggerParam> {
+struct ConsoleLoggerParam : public XGBoostParameter<ConsoleLoggerParam> {
   bool silent;  // deprecated.
   int verbosity;
 

include/xgboost/tree_model.h

@@ -60,6 +60,7 @@ struct TreeParam : public dmlc::Parameter<TreeParam> {
     // other arguments are set by the algorithm.
     DMLC_DECLARE_FIELD(num_roots).set_lower_bound(1).set_default(1)
         .describe("Number of start root of trees.");
+    DMLC_DECLARE_FIELD(num_nodes).set_lower_bound(1).set_default(1);
     DMLC_DECLARE_FIELD(num_feature)
         .describe("Number of features used in tree construction.");
     DMLC_DECLARE_FIELD(size_leaf_vector).set_lower_bound(0).set_default(0)
@@ -83,7 +84,7 @@ struct RTreeNodeStat {
   /*! \brief weight of current node */
   bst_float base_weight;
   /*! \brief number of child that is leaf node known up to now */
-  int leaf_child_cnt;
+  int leaf_child_cnt {0};
   bool operator==(const RTreeNodeStat& b) const {
     return loss_chg == b.loss_chg && sum_hess == b.sum_hess &&
            base_weight == b.base_weight && leaf_child_cnt == b.leaf_child_cnt;
@@ -98,6 +99,7 @@ class RegTree : public Model {
  public:
   /*! \brief auxiliary statistics of node to help tree building */
   using SplitCondT = bst_float;
+  static constexpr int32_t kInvalidNodeId {-1};
   /*! \brief tree node */
   class Node {
    public:
@@ -106,6 +108,12 @@ class RegTree : public Model {
       static_assert(sizeof(Node) == 4 * sizeof(int) + sizeof(Info),
                     "Node: 64 bit align");
     }
+    Node(int32_t cleft, int32_t cright, int32_t parent,
+         uint32_t split_ind, float split_cond, bool default_left) :
+        parent_{parent}, cleft_{cleft}, cright_{cright} {
+      this->SetSplit(split_ind, split_cond, default_left);
+    }
+
     /*! \brief index of left child */
     XGBOOST_DEVICE int LeftChild() const {
       return this->cleft_;
@@ -219,11 +227,11 @@ class RegTree : public Model {
     };
     // pointer to parent, highest bit is used to
     // indicate whether it's a left child or not
-    int parent_;
+    int32_t parent_{kInvalidNodeId};
     // pointer to left, right
-    int cleft_, cright_;
+    int32_t cleft_{kInvalidNodeId}, cright_{kInvalidNodeId};
     // split feature index, left split or right split depends on the highest bit
-    unsigned sindex_{0};
+    uint32_t sindex_{0};
     // extra info
     Info info_;
   };