[PYTHON-DIST] Distributed xgboost python training API.

include/xgboost/c_api.h

@@ -358,6 +358,30 @@ XGB_DLL int XGBoosterDumpModelWithFeatures(BoosterHandle handle,
                                            bst_ulong *out_len,
                                            const char ***out_models);
 
+/*!
+ * \brief Get string attribute from Booster.
+ * \param handle handle
+ * \param key The key of the attribute.
+ * \param out The result attribute, can be NULL if the attribute do not exist.
+ * \param success Whether the result is contained in out.
+ * \return 0 when success, -1 when failure happens
+ */
+XGB_DLL int XGBoosterGetAttr(BoosterHandle handle,
+                             const char* key,
+                             const char** out,
+                             int *success);
+/*!
+ * \brief Set string attribute.
+ *
+ * \param handle handle
+ * \param key The key of the symbol.
+ * \param value The value to be saved.
+ * \return 0 when success, -1 when failure happens
+ */
+XGB_DLL int XGBoosterSetAttr(BoosterHandle handle,
+                             const char* key,
+                             const char* value);
+
 // --- Distributed training API----
 // NOTE: functions in rabit/c_api.h will be also available in libxgboost.so
 /*!
@@ -376,6 +400,6 @@ XGB_DLL int XGBoosterLoadRabitCheckpoint(
  * \param handle handle
  * \return 0 when success, -1 when failure happens
  */
-XGB_DLL int XGBoosterSaveRabitCheckPoint(BoosterHandle handle);
+XGB_DLL int XGBoosterSaveRabitCheckpoint(BoosterHandle handle);
 
 #endif  // XGBOOST_C_API_H_

include/xgboost/learner.h

@@ -109,6 +109,21 @@ class Learner : public rabit::Serializable {
                        std::vector<float> *out_preds,
                        unsigned ntree_limit = 0,
                        bool pred_leaf = false) const = 0;
+  /*!
+   * \brief Set additional attribute to the Booster.
+   *  The property will be saved along the booster.
+   * \param key The key of the property.
+   * \param value The value of the property.
+   */
+  virtual void SetAttr(const std::string& key, const std::string& value) = 0;
+  /*!
+   * \brief Get attribute from the booster.
+   *  The property will be saved along the booster.
+   * \param key The key of the attribute.
+   * \param out The output value.
+   * \return Whether the key is contained in the attribute.
+   */
+  virtual bool GetAttr(const std::string& key, std::string* out) const = 0;
   /*!
    * \return whether the model allow lazy checkpoint in rabit.
    */