Merge pull request #1380 from yandex/catboost-models

Catboost models

dbms/src/Core/ErrorCodes.cpp

@@ -384,6 +384,8 @@ namespace ErrorCodes
     extern const int UNKNOWN_STATUS_OF_DISTRIBUTED_DDL_TASK = 379;
     extern const int CANNOT_KILL = 380;
     extern const int HTTP_LENGTH_REQUIRED = 381;
+    extern const int CANNOT_LOAD_CATBOOST_MODEL = 382;
+    extern const int CANNOT_APPLY_CATBOOST_MODEL = 383;
 
     extern const int KEEPER_EXCEPTION = 999;
     extern const int POCO_EXCEPTION = 1000;

dbms/src/Databases/DatabaseDictionary.cpp

@@ -26,18 +26,19 @@ void DatabaseDictionary::loadTables(Context & context, ThreadPool * thread_pool,
 
 Tables DatabaseDictionary::loadTables()
 {
-    const std::lock_guard<std::mutex> lock_dictionaries {external_dictionaries.dictionaries_mutex};
+    auto objects_map = external_dictionaries.getObjectsMap();
+    const auto & dictionaries = objects_map.get();
 
     Tables tables;
-    for (const auto & pair : external_dictionaries.dictionaries)
+    for (const auto & pair : dictionaries)
     {
         const std::string & name = pair.first;
         if (deleted_tables.count(name))
             continue;
-        auto dict_ptr = pair.second.dict;
+        auto dict_ptr = std::static_pointer_cast<IDictionaryBase>(pair.second.loadable);
         if (dict_ptr)
         {
-            const DictionaryStructure & dictionary_structure = dict_ptr->get()->getStructure();
+            const DictionaryStructure & dictionary_structure = dict_ptr->getStructure();
             auto columns = StorageDictionary::getNamesAndTypes(dictionary_structure);
             tables[name] = StorageDictionary::create(name, columns, {}, {}, {}, dictionary_structure, name);
         }
@@ -50,26 +51,28 @@ bool DatabaseDictionary::isTableExist(
     const Context & context,
     const String & table_name) const
 {
-    const std::lock_guard<std::mutex> lock_dictionaries {external_dictionaries.dictionaries_mutex};
+    auto objects_map = external_dictionaries.getObjectsMap();
-    return external_dictionaries.dictionaries.count(table_name) && !deleted_tables.count(table_name);
+    const auto & dictionaries = objects_map.get();
+    return dictionaries.count(table_name) && !deleted_tables.count(table_name);
 }
 
 StoragePtr DatabaseDictionary::tryGetTable(
     const Context & context,
     const String & table_name)
 {
-    const std::lock_guard<std::mutex> lock_dictionaries {external_dictionaries.dictionaries_mutex};
+    auto objects_map = external_dictionaries.getObjectsMap();
+    const auto & dictionaries = objects_map.get();
 
     if (deleted_tables.count(table_name))
         return {};
     {
-        auto it = external_dictionaries.dictionaries.find(table_name);
+        auto it = dictionaries.find(table_name);
-        if (it != external_dictionaries.dictionaries.end())
+        if (it != dictionaries.end())
         {
-            const auto & dict_ptr = it->second.dict;
+            const auto & dict_ptr = std::static_pointer_cast<IDictionaryBase>(it->second.loadable);
             if (dict_ptr)
             {
-                const DictionaryStructure & dictionary_structure = dict_ptr->get()->getStructure();
+                const DictionaryStructure & dictionary_structure = dict_ptr->getStructure();
                 auto columns = StorageDictionary::getNamesAndTypes(dictionary_structure);
                 return StorageDictionary::create(table_name, columns, {}, {}, {}, dictionary_structure, table_name);
             }
@@ -86,9 +89,10 @@ DatabaseIteratorPtr DatabaseDictionary::getIterator(const Context & context)
 
 bool DatabaseDictionary::empty(const Context & context) const
 {
-    const std::lock_guard<std::mutex> lock_dictionaries {external_dictionaries.dictionaries_mutex};
+    auto objects_map = external_dictionaries.getObjectsMap();
-    for (const auto & pair : external_dictionaries.dictionaries)
+    const auto & dictionaries = objects_map.get();
-        if (pair.second.dict && !deleted_tables.count(pair.first))
+    for (const auto & pair : dictionaries)
+        if (pair.second.loadable && !deleted_tables.count(pair.first))
             return false;
     return true;
 }
@@ -119,7 +123,7 @@ void DatabaseDictionary::removeTable(
     if (!isTableExist(context, table_name))
         throw Exception("Table " + name + "." + table_name + " doesn't exist.", ErrorCodes::UNKNOWN_TABLE);
 
-    const std::lock_guard<std::mutex> lock_dictionaries {external_dictionaries.dictionaries_mutex};
+    auto objects_map = external_dictionaries.getObjectsMap();
     deleted_tables.insert(table_name);
 }
 
@@ -156,7 +160,6 @@ ASTPtr DatabaseDictionary::getCreateQuery(
     const String & table_name) const
 {
     throw Exception("DatabaseDictionary: getCreateQuery() is not supported", ErrorCodes::NOT_IMPLEMENTED);
-    return nullptr;
 }
 
 void DatabaseDictionary::shutdown()

dbms/src/Dictionaries/CacheDictionary.h

@@ -54,7 +54,7 @@ public:
 
     bool isCached() const override { return true; }
 
-    DictionaryPtr clone() const override { return std::make_unique<CacheDictionary>(*this); }
+    std::unique_ptr<IExternalLoadable> clone() const override { return std::make_unique<CacheDictionary>(*this); }
 
     const IDictionarySource * getSource() const override { return source_ptr.get(); }
 

dbms/src/Dictionaries/CatBoostModel.cpp

@@ -0,0 +1,523 @@
+#include <Dictionaries/CatBoostModel.h>
+#include <Core/FieldVisitors.h>
+#include <mutex>
+#include <Columns/ColumnString.h>
+#include <Columns/ColumnFixedString.h>
+#include <Columns/ColumnVector.h>
+#include <Common/typeid_cast.h>
+#include <IO/WriteBufferFromString.h>
+#include <IO/Operators.h>
+#include <Common/PODArray.h>
+#include <Common/SharedLibrary.h>
+
+namespace DB
+{
+
+namespace ErrorCodes
+{
+extern const int LOGICAL_ERROR;
+extern const int BAD_ARGUMENTS;
+extern const int CANNOT_LOAD_CATBOOST_MODEL;
+extern const int CANNOT_APPLY_CATBOOST_MODEL;
+}
+
+
+/// CatBoost wrapper interface functions.
+struct CatBoostWrapperAPI
+{
+    typedef void ModelCalcerHandle;
+
+    ModelCalcerHandle * (* ModelCalcerCreate)();
+
+    void (* ModelCalcerDelete)(ModelCalcerHandle * calcer);
+
+    const char * (* GetErrorString)();
+
+    bool (* LoadFullModelFromFile)(ModelCalcerHandle * calcer, const char * filename);
+
+    bool (* CalcModelPredictionFlat)(ModelCalcerHandle * calcer, size_t docCount,
+                                     const float ** floatFeatures, size_t floatFeaturesSize,
+                                     double * result, size_t resultSize);
+
+    bool (* CalcModelPrediction)(ModelCalcerHandle * calcer, size_t docCount,
+                                 const float ** floatFeatures, size_t floatFeaturesSize,
+                                 const char *** catFeatures, size_t catFeaturesSize,
+                                 double * result, size_t resultSize);
+
+    bool (* CalcModelPredictionWithHashedCatFeatures)(ModelCalcerHandle * calcer, size_t docCount,
+                                                      const float ** floatFeatures, size_t floatFeaturesSize,
+                                                      const int ** catFeatures, size_t catFeaturesSize,
+                                                      double * result, size_t resultSize);
+
+    int (* GetStringCatFeatureHash)(const char * data, size_t size);
+
+    int (* GetIntegerCatFeatureHash)(long long val);
+
+    size_t (* GetFloatFeaturesCount)(ModelCalcerHandle* calcer);
+
+    size_t (* GetCatFeaturesCount)(ModelCalcerHandle* calcer);
+};
+
+
+namespace
+{
+
+class CatBoostModelHolder
+{
+private:
+    CatBoostWrapperAPI::ModelCalcerHandle * handle;
+    const CatBoostWrapperAPI * api;
+public:
+    explicit CatBoostModelHolder(const CatBoostWrapperAPI * api) : api(api) { handle = api->ModelCalcerCreate(); }
+    ~CatBoostModelHolder() { api->ModelCalcerDelete(handle); }
+
+    CatBoostWrapperAPI::ModelCalcerHandle * get() { return handle; }
+    explicit operator CatBoostWrapperAPI::ModelCalcerHandle * () { return handle; }
+};
+
+
+class CatBoostModelImpl : public ICatBoostModel
+{
+public:
+    CatBoostModelImpl(const CatBoostWrapperAPI * api, const std::string & model_path) : api(api)
+    {
+        auto handle_ = std::make_unique<CatBoostModelHolder>(api);
+        if (!handle_)
+        {
+            std::string msg = "Cannot create CatBoost model: ";
+            throw Exception(msg + api->GetErrorString(), ErrorCodes::CANNOT_LOAD_CATBOOST_MODEL);
+        }
+        if (!api->LoadFullModelFromFile(handle_->get(), model_path.c_str()))
+        {
+            std::string msg = "Cannot load CatBoost model: ";
+            throw Exception(msg + api->GetErrorString(), ErrorCodes::CANNOT_LOAD_CATBOOST_MODEL);
+        }
+        handle = std::move(handle_);
+    }
+
+    ColumnPtr evaluate(const ConstColumnPlainPtrs & columns,
+                       size_t float_features_count, size_t cat_features_count) const override
+    {
+        checkFeaturesCount(float_features_count, cat_features_count);
+
+        if (columns.empty())
+            throw Exception("Got empty columns list for CatBoost model.", ErrorCodes::BAD_ARGUMENTS);
+
+        if (columns.size() != float_features_count + cat_features_count)
+        {
+            std::string msg;
+            {
+                WriteBufferFromString buffer(msg);
+                buffer << "Number of columns is different with number of features: ";
+                buffer << columns.size() << " vs " << float_features_count << " + " << cat_features_count;
+            }
+            throw Exception(msg, ErrorCodes::BAD_ARGUMENTS);
+        }
+
+        for (size_t i = 0; i < float_features_count; ++i)
+        {
+            if (!columns[i]->isNumeric())
+            {
+                std::string msg;
+                {
+                    WriteBufferFromString buffer(msg);
+                    buffer << "Column " << i << "should be numeric to make float feature.";
+                }
+                throw Exception(msg, ErrorCodes::BAD_ARGUMENTS);
+            }
+        }
+
+        bool cat_features_are_strings = true;
+        for (size_t i = float_features_count; i < float_features_count + cat_features_count; ++i)
+        {
+            auto column = columns[i];
+            if (column->isNumeric())
+                cat_features_are_strings = false;
+            else if (!(typeid_cast<const ColumnString *>(column)
+                       || typeid_cast<const ColumnFixedString *>(column)))
+            {
+                std::string msg;
+                {
+                    WriteBufferFromString buffer(msg);
+                    buffer << "Column " << i << "should be numeric or string.";
+                }
+                throw Exception(msg, ErrorCodes::BAD_ARGUMENTS);
+            }
+        }
+
+        return evalImpl(columns, float_features_count, cat_features_count, cat_features_are_strings);
+    }
+
+    void checkFeaturesCount(size_t float_features_count, size_t cat_features_count) const
+    {
+        if (api->GetFloatFeaturesCount)
+        {
+            size_t float_features_in_model = api->GetFloatFeaturesCount(handle->get());
+            if (float_features_count != float_features_in_model)
+                throw Exception("CatBoost model expected " + std::to_string(float_features_in_model) + " float features"
+                                + ", but " + std::to_string(float_features_count) + " was provided.");
+        }
+
+        if (api->GetCatFeaturesCount)
+        {
+            size_t cat_features_in_model = api->GetCatFeaturesCount(handle->get());
+            if (cat_features_count != cat_features_in_model)
+                throw Exception("CatBoost model expected " + std::to_string(cat_features_in_model) + " cat features"
+                                + ", but " + std::to_string(cat_features_count) + " was provided.");
+        }
+    }
+
+private:
+    std::unique_ptr<CatBoostModelHolder> handle;
+    const CatBoostWrapperAPI * api;
+
+    /// Buffer should be allocated with features_count * column->size() elements.
+    /// Place column elements in positions buffer[0], buffer[features_count], ... , buffer[size * features_count]
+    template <typename T>
+    void placeColumnAsNumber(const IColumn * column, T * buffer, size_t features_count) const
+    {
+        size_t size = column->size();
+        FieldVisitorConvertToNumber<T> visitor;
+        for (size_t i = 0; i < size; ++i)
+        {
+            /// TODO: Replace with column visitor.
+            Field field;
+            column->get(i, field);
+            *buffer = applyVisitor(visitor, field);
+            buffer += features_count;
+        }
+    }
+
+    /// Buffer should be allocated with features_count * column->size() elements.
+    /// Place string pointers in positions buffer[0], buffer[features_count], ... , buffer[size * features_count]
+    void placeStringColumn(const ColumnString & column, const char ** buffer, size_t features_count) const
+    {
+        size_t size = column.size();
+        for (size_t i = 0; i < size; ++i)
+        {
+            *buffer = const_cast<char *>(column.getDataAtWithTerminatingZero(i).data);
+            buffer += features_count;
+        }
+    }
+
+    /// Buffer should be allocated with features_count * column->size() elements.
+    /// Place string pointers in positions buffer[0], buffer[features_count], ... , buffer[size * features_count]
+    /// Returns PODArray which holds data (because ColumnFixedString doesn't store terminating zero).
+    PODArray<char> placeFixedStringColumn(
+            const ColumnFixedString & column, const char ** buffer, size_t features_count) const
+    {
+        size_t size = column.size();
+        size_t str_size = column.getN();
+        PODArray<char> data(size * (str_size + 1));
+        char * data_ptr = data.data();
+
+        for (size_t i = 0; i < size; ++i)
+        {
+            auto ref = column.getDataAt(i);
+            memcpy(data_ptr, ref.data, ref.size);
+            data_ptr[ref.size] = 0;
+            *buffer = data_ptr;
+            data_ptr += ref.size + 1;
+            buffer += features_count;
+        }
+
+        return data;
+    }
+
+    /// Place columns into buffer, returns column which holds placed data. Buffer should contains column->size() values.
+    template <typename T>
+    ColumnPtr placeNumericColumns(const ConstColumnPlainPtrs & columns,
+                                  size_t offset, size_t size, const T** buffer) const
+    {
+        if (size == 0)
+            return nullptr;
+        size_t column_size = columns[offset]->size();
+        auto data_column = std::make_shared<ColumnVector<T>>(size * column_size);
+        T* data = data_column->getData().data();
+        for (size_t i = 0; i < size; ++i)
+        {
+            auto column = columns[offset + i];
+            if (column->isNumeric())
+                placeColumnAsNumber(column, data + i, size);
+        }
+
+        for (size_t i = 0; i < column_size; ++i)
+        {
+            *buffer = data;
+            ++buffer;
+            data += size;
+        }
+
+        return data_column;
+    }
+
+    /// Place columns into buffer, returns data which was used for fixed string columns.
+    /// Buffer should contains column->size() values, each value contains size strings.
+    std::vector<PODArray<char>> placeStringColumns(
+            const ConstColumnPlainPtrs & columns, size_t offset, size_t size, const char ** buffer) const
+    {
+        if (size == 0)
+            return {};
+
+        std::vector<PODArray<char>> data;
+        for (size_t i = 0; i < size; ++i)
+        {
+            auto column = columns[offset + i];
+            if (auto column_string = typeid_cast<const ColumnString *>(column))
+                placeStringColumn(*column_string, buffer + i, size);
+            else if (auto column_fixed_string = typeid_cast<const ColumnFixedString *>(column))
+                data.push_back(placeFixedStringColumn(*column_fixed_string, buffer + i, size));
+            else
+                throw Exception("Cannot place string column.", ErrorCodes::LOGICAL_ERROR);
+        }
+
+        return data;
+    }
+
+    /// Calc hash for string cat feature at ps positions.
+    template <typename Column>
+    void calcStringHashes(const Column * column, size_t ps, const int ** buffer) const
+    {
+        size_t column_size = column->size();
+        for (size_t j = 0; j < column_size; ++j)
+        {
+            auto ref = column->getDataAt(j);
+            const_cast<int *>(*buffer)[ps] = api->GetStringCatFeatureHash(ref.data, ref.size);
+            ++buffer;
+        }
+    }
+
+    /// Calc hash for int cat feature at ps position. Buffer at positions ps should contains unhashed values.
+    void calcIntHashes(size_t column_size, size_t ps, const int ** buffer) const
+    {
+        for (size_t j = 0; j < column_size; ++j)
+        {
+            const_cast<int *>(*buffer)[ps] = api->GetIntegerCatFeatureHash((*buffer)[ps]);
+            ++buffer;
+        }
+    }
+
+    /// buffer contains column->size() rows and size columns.
+    /// For int cat features calc hash inplace.
+    /// For string cat features calc hash from column rows.
+    void calcHashes(const ConstColumnPlainPtrs & columns, size_t offset, size_t size, const int ** buffer) const
+    {
+        if (size == 0)
+            return;
+        size_t column_size = columns[offset]->size();
+
+        std::vector<PODArray<char>> data;
+        for (size_t i = 0; i < size; ++i)
+        {
+            auto column = columns[offset + i];
+            if (auto column_string = typeid_cast<const ColumnString *>(column))
+                calcStringHashes(column_string, i, buffer);
+            else if (auto column_fixed_string = typeid_cast<const ColumnFixedString *>(column))
+                calcStringHashes(column_fixed_string, i, buffer);
+            else
+                calcIntHashes(column_size, i, buffer);
+        }
+    }
+
+    /// buffer[column_size * cat_features_count] -> char * => cat_features[column_size][cat_features_count] -> char *
+    void fillCatFeaturesBuffer(const char *** cat_features, const char ** buffer,
+                               size_t column_size, size_t cat_features_count) const
+    {
+        for (size_t i = 0; i < column_size; ++i)
+        {
+            *cat_features = buffer;
+            ++cat_features;
+            buffer += cat_features_count;
+        }
+    }
+
+    /// Convert values to row-oriented format and call evaluation function from CatBoost wrapper api.
+    ///  * CalcModelPredictionFlat if no cat features
+    ///  * CalcModelPrediction if all cat features are strings
+    ///  * CalcModelPredictionWithHashedCatFeatures if has int cat features.
+    ColumnPtr evalImpl(const ConstColumnPlainPtrs & columns, size_t float_features_count, size_t cat_features_count,
+                       bool cat_features_are_strings) const
+    {
+        std::string error_msg = "Error occurred while applying CatBoost model: ";
+        size_t column_size = columns.front()->size();
+
+        auto result= std::make_shared<ColumnFloat64>(column_size);
+        auto result_buf = result->getData().data();
+
+        /// Prepare float features.
+        PODArray<const float *> float_features(column_size);
+        auto float_features_buf = float_features.data();
+        /// Store all float data into single column. float_features is a list of pointers to it.
+        auto float_features_col = placeNumericColumns<float>(columns, 0, float_features_count, float_features_buf);
+
+        if (cat_features_count == 0)
+        {
+            if (!api->CalcModelPredictionFlat(handle->get(), column_size,
+                                              float_features_buf, float_features_count,
+                                              result_buf, column_size))
+            {
+
+                throw Exception(error_msg + api->GetErrorString(), ErrorCodes::CANNOT_APPLY_CATBOOST_MODEL);
+            }
+            return result;
+        }
+
+        /// Prepare cat features.
+        if (cat_features_are_strings)
+        {
+            /// cat_features_holder stores pointers to ColumnString data or fixed_strings_data.
+            PODArray<const char *> cat_features_holder(cat_features_count * column_size);
+            PODArray<const char **> cat_features(column_size);
+            auto cat_features_buf = cat_features.data();
+
+            fillCatFeaturesBuffer(cat_features_buf, cat_features_holder.data(), column_size, cat_features_count);
+            /// Fixed strings are stored without termination zero, so have to copy data into fixed_strings_data.
+            auto fixed_strings_data = placeStringColumns(columns, float_features_count,
+                                                         cat_features_count, cat_features_holder.data());
+
+            if (!api->CalcModelPrediction(handle->get(), column_size,
+                                          float_features_buf, float_features_count,
+                                          cat_features_buf, cat_features_count,
+                                          result_buf, column_size))
+            {
+                throw Exception(error_msg + api->GetErrorString(), ErrorCodes::CANNOT_APPLY_CATBOOST_MODEL);
+            }
+        }
+        else
+        {
+            PODArray<const int *> cat_features(column_size);
+            auto cat_features_buf = cat_features.data();
+            auto cat_features_col = placeNumericColumns<int>(columns, float_features_count,
+                                                             cat_features_count, cat_features_buf);
+            calcHashes(columns, float_features_count, cat_features_count, cat_features_buf);
+            if (!api->CalcModelPredictionWithHashedCatFeatures(
+                    handle->get(), column_size,
+                    float_features_buf, float_features_count,
+                    cat_features_buf, cat_features_count,
+                    result_buf, column_size))
+            {
+                throw Exception(error_msg + api->GetErrorString(), ErrorCodes::CANNOT_APPLY_CATBOOST_MODEL);
+            }
+        }
+
+        return result;
+    }
+};
+
+
+/// Holds CatBoost wrapper library and provides wrapper interface.
+class CatBoostLibHolder: public CatBoostWrapperAPIProvider
+{
+public:
+    explicit CatBoostLibHolder(const std::string & lib_path) : lib_path(lib_path), lib(lib_path) { initAPI(); }
+
+    const CatBoostWrapperAPI & getAPI() const override { return api; }
+    const std::string & getCurrentPath() const { return lib_path; }
+
+private:
+    CatBoostWrapperAPI api;
+    std::string lib_path;
+    SharedLibrary lib;
+
+    void initAPI();
+
+    template <typename T>
+    void load(T& func, const std::string & name) { func = lib.get<T>(name); }
+
+    template <typename T>
+    void tryLoad(T& func, const std::string & name) { func = lib.tryGet<T>(name); }
+};
+
+void CatBoostLibHolder::initAPI()
+{
+    load(api.ModelCalcerCreate, "ModelCalcerCreate");
+    load(api.ModelCalcerDelete, "ModelCalcerDelete");
+    load(api.GetErrorString, "GetErrorString");
+    load(api.LoadFullModelFromFile, "LoadFullModelFromFile");
+    load(api.CalcModelPredictionFlat, "CalcModelPredictionFlat");
+    load(api.CalcModelPrediction, "CalcModelPrediction");
+    load(api.CalcModelPredictionWithHashedCatFeatures, "CalcModelPredictionWithHashedCatFeatures");
+    load(api.GetStringCatFeatureHash, "GetStringCatFeatureHash");
+    load(api.GetIntegerCatFeatureHash, "GetIntegerCatFeatureHash");
+
+    tryLoad(api.GetFloatFeaturesCount, "GetFloatFeaturesCount");
+    tryLoad(api.GetCatFeaturesCount, "GetCatFeaturesCount");
+}
+
+std::shared_ptr<CatBoostLibHolder> getCatBoostWrapperHolder(const std::string & lib_path)
+{
+    static std::weak_ptr<CatBoostLibHolder> ptr;
+    static std::mutex mutex;
+
+    std::lock_guard<std::mutex> lock(mutex);
+    auto result = ptr.lock();
+
+    if (!result || result->getCurrentPath() != lib_path)
+    {
+        result = std::make_shared<CatBoostLibHolder>(lib_path);
+        /// This assignment is not atomic, which prevents from creating lock only inside 'if'.
+        ptr = result;
+    }
+
+    return result;
+}
+
+}
+
+
+CatBoostModel::CatBoostModel(const std::string & name, const std::string & model_path, const std::string & lib_path,
+                             const ExternalLoadableLifetime & lifetime,
+                             size_t float_features_count, size_t cat_features_count)
+    : name(name), model_path(model_path), lib_path(lib_path), lifetime(lifetime),
+      float_features_count(float_features_count), cat_features_count(cat_features_count)
+{
+    try
+    {
+        init(lib_path);
+    }
+    catch (...)
+    {
+        creation_exception = std::current_exception();
+    }
+}
+
+void CatBoostModel::init(const std::string & lib_path)
+{
+    api_provider = getCatBoostWrapperHolder(lib_path);
+    api = &api_provider->getAPI();
+    model = std::make_unique<CatBoostModelImpl>(api, model_path);
+}
+
+const ExternalLoadableLifetime & CatBoostModel::getLifetime() const
+{
+    return lifetime;
+}
+
+bool CatBoostModel::isModified() const
+{
+    return true;
+}
+
+std::unique_ptr<IExternalLoadable> CatBoostModel::clone() const
+{
+    return std::make_unique<CatBoostModel>(name, model_path, lib_path, lifetime, float_features_count, cat_features_count);
+}
+
+size_t CatBoostModel::getFloatFeaturesCount() const
+{
+    return float_features_count;
+}
+
+size_t CatBoostModel::getCatFeaturesCount() const
+{
+    return cat_features_count;
+}
+
+ColumnPtr CatBoostModel::evaluate(const ConstColumnPlainPtrs & columns) const
+{
+    if (!model)
+        throw Exception("CatBoost model was not loaded.", ErrorCodes::LOGICAL_ERROR);
+    return model->evaluate(columns, float_features_count, cat_features_count);
+}
+
+}

dbms/src/Dictionaries/CatBoostModel.h

@@ -0,0 +1,79 @@
+#pragma once
+#include <Interpreters/IExternalLoadable.h>
+#include <Columns/IColumn.h>
+#include <Columns/ColumnsNumber.h>
+
+
+namespace DB
+{
+
+/// CatBoost wrapper interface functions.
+struct CatBoostWrapperAPI;
+class CatBoostWrapperAPIProvider
+{
+public:
+    virtual ~CatBoostWrapperAPIProvider() = default;
+    virtual const CatBoostWrapperAPI & getAPI() const = 0;
+};
+
+/// CatBoost model interface.
+class ICatBoostModel
+{
+public:
+    virtual ~ICatBoostModel() = default;
+    /// Evaluate model. Use first `float_features_count` columns as float features,
+    /// the others `cat_features_count` as categorical features.
+    virtual ColumnPtr evaluate(const ConstColumnPlainPtrs & columns, size_t float_features_count, size_t cat_features_count) const = 0;
+};
+
+/// General ML model evaluator interface.
+class IModel : public IExternalLoadable
+{
+public:
+    virtual ColumnPtr evaluate(const ConstColumnPlainPtrs & columns) const = 0;
+};
+
+class CatBoostModel : public IModel
+{
+public:
+    CatBoostModel(const std::string & name, const std::string & model_path,
+                  const std::string & lib_path, const ExternalLoadableLifetime & lifetime,
+                  size_t float_features_count, size_t cat_features_count);
+
+    ColumnPtr evaluate(const ConstColumnPlainPtrs & columns) const override;
+
+    size_t getFloatFeaturesCount() const;
+    size_t getCatFeaturesCount() const;
+
+    /// IExternalLoadable interface.
+
+    const ExternalLoadableLifetime & getLifetime() const override;
+
+    std::string getName() const override { return name; }
+
+    bool supportUpdates() const override { return true; }
+
+    bool isModified() const override;
+
+    std::unique_ptr<IExternalLoadable> clone() const override;
+
+    std::exception_ptr getCreationException() const override { return creation_exception; }
+
+private:
+    std::string name;
+    std::string model_path;
+    std::string lib_path;
+    ExternalLoadableLifetime lifetime;
+    std::exception_ptr creation_exception;
+    std::shared_ptr<CatBoostWrapperAPIProvider> api_provider;
+    const CatBoostWrapperAPI * api;
+
+    std::unique_ptr<ICatBoostModel> model;
+
+    size_t float_features_count;
+    size_t cat_features_count;
+
+    void init(const std::string & lib_path);
+};
+
+}

dbms/src/Dictionaries/ComplexKeyCacheDictionary.h

@@ -98,7 +98,7 @@ public:
         return true;
     }
 
-    DictionaryPtr clone() const override
+    std::unique_ptr<IExternalLoadable> clone() const override
     {
         return std::make_unique<ComplexKeyCacheDictionary>(*this);
     }

dbms/src/Dictionaries/ComplexKeyHashedDictionary.h

@@ -46,7 +46,7 @@ public:
 
     bool isCached() const override { return false; }
 
-    DictionaryPtr clone() const override { return std::make_unique<ComplexKeyHashedDictionary>(*this); }
+    std::unique_ptr<IExternalLoadable> clone() const override { return std::make_unique<ComplexKeyHashedDictionary>(*this); }
 
     const IDictionarySource * getSource() const override { return source_ptr.get(); }
 

dbms/src/Dictionaries/DictionaryFactory.h

@@ -13,7 +13,7 @@ class Context;
 class DictionaryFactory : public ext::singleton<DictionaryFactory>
 {
 public:
-    DictionaryPtr create(const std::string & name, Poco::Util::AbstractConfiguration & config,
+    DictionaryPtr create(const std::string & name, const Poco::Util::AbstractConfiguration & config,
         const std::string & config_prefix, Context & context) const;
 };
 

dbms/src/Dictionaries/DictionarySourceFactory.cpp

@@ -90,7 +90,7 @@ DictionarySourceFactory::DictionarySourceFactory()
 
 
 DictionarySourcePtr DictionarySourceFactory::create(
-    const std::string & name, Poco::Util::AbstractConfiguration & config, const std::string & config_prefix,
+    const std::string & name, const Poco::Util::AbstractConfiguration & config, const std::string & config_prefix,
     const DictionaryStructure & dict_struct, Context & context) const
 {
     Poco::Util::AbstractConfiguration::Keys keys;

dbms/src/Dictionaries/DictionarySourceFactory.h

@@ -25,7 +25,7 @@ public:
     DictionarySourceFactory();
 
     DictionarySourcePtr create(
-        const std::string & name, Poco::Util::AbstractConfiguration & config, const std::string & config_prefix,
+        const std::string & name, const Poco::Util::AbstractConfiguration & config, const std::string & config_prefix,
         const DictionaryStructure & dict_struct, Context & context) const;
 };
 

dbms/src/Dictionaries/DictionaryStructure.cpp

@@ -105,16 +105,6 @@ std::string toString(const AttributeUnderlyingType type)
 }
 
 
-DictionaryLifetime::DictionaryLifetime(const Poco::Util::AbstractConfiguration & config, const std::string & config_prefix)
-{
-    const auto & lifetime_min_key = config_prefix + ".min";
-    const auto has_min = config.has(lifetime_min_key);
-
-    this->min_sec = has_min ? config.getInt(lifetime_min_key) : config.getInt(config_prefix);
-    this->max_sec = has_min ? config.getInt(config_prefix + ".max") : this->min_sec;
-}
-
-
 DictionarySpecialAttribute::DictionarySpecialAttribute(const Poco::Util::AbstractConfiguration & config, const std::string & config_prefix)
     : name{config.getString(config_prefix + ".name", "")},
       expression{config.getString(config_prefix + ".expression", "")}

dbms/src/Dictionaries/DictionaryStructure.h

@@ -4,6 +4,7 @@
 #include <IO/ReadBufferFromString.h>
 #include <IO/WriteBuffer.h>
 #include <IO/WriteHelpers.h>
+#include <Interpreters/IExternalLoadable.h>
 #include <Poco/Util/AbstractConfiguration.h>
 #include <ext/range.h>
 #include <numeric>
@@ -42,13 +43,7 @@ std::string toString(const AttributeUnderlyingType type);
 
 
 /// Min and max lifetimes for a dictionary or it's entry
-struct DictionaryLifetime final
+using DictionaryLifetime = ExternalLoadableLifetime;
-{
-    UInt64 min_sec;
-    UInt64 max_sec;
-
-    DictionaryLifetime(const Poco::Util::AbstractConfiguration & config, const std::string & config_prefix);
-};
 
 
 /** Holds the description of a single dictionary attribute:

dbms/src/Dictionaries/FlatDictionary.h

@@ -41,7 +41,7 @@ public:
 
     bool isCached() const override { return false; }
 
-    DictionaryPtr clone() const override { return std::make_unique<FlatDictionary>(*this); }
+    std::unique_ptr<IExternalLoadable> clone() const override { return std::make_unique<FlatDictionary>(*this); }
 
     const IDictionarySource * getSource() const override { return source_ptr.get(); }
 

dbms/src/Dictionaries/HashedDictionary.h

@@ -40,7 +40,7 @@ public:
 
     bool isCached() const override { return false; }
 
-    DictionaryPtr clone() const override { return std::make_unique<HashedDictionary>(*this); }
+    std::unique_ptr<IExternalLoadable> clone() const override { return std::make_unique<HashedDictionary>(*this); }
 
     const IDictionarySource * getSource() const override { return source_ptr.get(); }
 

dbms/src/Dictionaries/IDictionary.h

@@ -1,22 +1,21 @@
 #pragma once
 
 #include <Core/Field.h>
+#include <Interpreters/IExternalLoadable.h>
 #include <common/StringRef.h>
 #include <Core/Names.h>
 #include <Poco/Util/XMLConfiguration.h>
 #include <Common/PODArray.h>
 #include <memory>
 #include <chrono>
+#include <Dictionaries/IDictionarySource.h>
 
 namespace DB
 {
 
-class IDictionarySource;
-
 struct IDictionaryBase;
 using DictionaryPtr = std::unique_ptr<IDictionaryBase>;
 
-struct DictionaryLifetime;
 struct DictionaryStructure;
 class ColumnString;
 
@@ -24,14 +23,10 @@ class IBlockInputStream;
 using BlockInputStreamPtr = std::shared_ptr<IBlockInputStream>;
 
 
-struct IDictionaryBase : public std::enable_shared_from_this<IDictionaryBase>
+struct IDictionaryBase : public IExternalLoadable
 {
     using Key = UInt64;
 
-    virtual std::exception_ptr getCreationException() const = 0;
-
-    virtual std::string getName() const = 0;
-
     virtual std::string getTypeName() const = 0;
 
     virtual size_t getBytesAllocated() const = 0;
@@ -45,12 +40,9 @@ struct IDictionaryBase : public std::enable_shared_from_this<IDictionaryBase>
     virtual double getLoadFactor() const = 0;
 
     virtual bool isCached() const = 0;
-    virtual DictionaryPtr clone() const = 0;
 
     virtual const IDictionarySource * getSource() const = 0;
 
-    virtual const DictionaryLifetime & getLifetime() const = 0;
-
     virtual const DictionaryStructure & getStructure() const = 0;
 
     virtual std::chrono::time_point<std::chrono::system_clock> getCreationTime() const = 0;
@@ -59,7 +51,23 @@ struct IDictionaryBase : public std::enable_shared_from_this<IDictionaryBase>
 
     virtual BlockInputStreamPtr getBlockInputStream(const Names & column_names, size_t max_block_size) const = 0;
 
-    virtual ~IDictionaryBase() = default;
+    bool supportUpdates() const override { return !isCached(); }
+
+    bool isModified() const override
+    {
+        auto source = getSource();
+        return source && source->isModified();
+    }
+
+    std::shared_ptr<IDictionaryBase> shared_from_this()
+    {
+        return std::static_pointer_cast<IDictionaryBase>(IExternalLoadable::shared_from_this());
+    }
+
+    std::shared_ptr<const IDictionaryBase> shared_from_this() const
+    {
+        return std::static_pointer_cast<const IDictionaryBase>(IExternalLoadable::shared_from_this());
+    }
 };
 
 

dbms/src/Dictionaries/RangeHashedDictionary.h

@@ -41,7 +41,7 @@ public:
 
     bool isCached() const override { return false; }
 
-    DictionaryPtr clone() const override { return std::make_unique<RangeHashedDictionary>(*this); }
+    std::unique_ptr<IExternalLoadable> clone() const override { return std::make_unique<RangeHashedDictionary>(*this); }
 
     const IDictionarySource * getSource() const override { return source_ptr.get(); }
 

dbms/src/Dictionaries/TrieDictionary.h

@@ -50,7 +50,7 @@ public:
 
     bool isCached() const override { return false; }
 
-    DictionaryPtr clone() const override { return std::make_unique<TrieDictionary>(*this); }
+    std::unique_ptr<IExternalLoadable> clone() const override { return std::make_unique<TrieDictionary>(*this); }
 
     const IDictionarySource * getSource() const override { return source_ptr.get(); }
 

dbms/src/Functions/FunctionsExternalModels.cpp

@@ -0,0 +1,62 @@
+#include <Functions/FunctionsExternalModels.h>
+#include <Functions/FunctionHelpers.h>
+#include <Functions/FunctionFactory.h>
+
+#include <Interpreters/Context.h>
+#include <Interpreters/ExternalModels.h>
+#include <DataTypes/DataTypeString.h>
+#include <DataTypes/DataTypesNumber.h>
+#include <Columns/ColumnString.h>
+#include <ext/range.h>
+
+namespace DB
+{
+
+FunctionPtr FunctionModelEvaluate::create(const Context & context)
+{
+    return std::make_shared<FunctionModelEvaluate>(context.getExternalModels());
+}
+
+namespace ErrorCodes
+{
+    extern const int ILLEGAL_TYPE_OF_ARGUMENT;
+    extern const int TOO_LESS_ARGUMENTS_FOR_FUNCTION;
+    extern const int ILLEGAL_COLUMN;
+}
+
+DataTypePtr FunctionModelEvaluate::getReturnTypeImpl(const DataTypes & arguments) const
+{
+    if (arguments.size() < 2)
+        throw Exception("Function " + getName() + " expects at least 2 arguments",
+                        ErrorCodes::TOO_LESS_ARGUMENTS_FOR_FUNCTION);
+
+    if (!checkDataType<DataTypeString>(arguments[0].get()))
+        throw Exception("Illegal type " + arguments[0]->getName() + " of first argument of function " + getName()
+                        + ", expected a string.", ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
+
+    return std::make_shared<DataTypeFloat64>();
+}
+
+void FunctionModelEvaluate::executeImpl(Block & block, const ColumnNumbers & arguments, size_t result)
+{
+    const auto name_col = checkAndGetColumnConst<ColumnString>(block.getByPosition(arguments[0]).column.get());
+    if (!name_col)
+        throw Exception("First argument of function " + getName() + " must be a constant string",
+                        ErrorCodes::ILLEGAL_COLUMN);
+
+    auto model = models.getModel(name_col->getValue<String>());
+
+    ConstColumnPlainPtrs columns;
+    columns.reserve(arguments.size());
+    for (auto i : ext::range(1, arguments.size()))
+        columns.push_back(block.getByPosition(arguments[i]).column.get());
+
+    block.getByPosition(result).column = model->evaluate(columns);
+}
+
+void registerFunctionsExternalModels(FunctionFactory & factory)
+{
+    factory.registerFunction<FunctionModelEvaluate>();
+}
+
+}

dbms/src/Functions/FunctionsExternalModels.h

@@ -0,0 +1,36 @@
+#pragma once
+#include <Functions/IFunction.h>
+
+namespace  DB
+{
+
+class ExternalModels;
+
+/// Evaluate external model.
+/// First argument - model name, the others - model arguments.
+///   * for CatBoost model - float features first, then categorical
+/// Result - Float64.
+class FunctionModelEvaluate final : public IFunction
+{
+public:
+    static constexpr auto name = "modelEvaluate";
+
+    static FunctionPtr create(const Context & context);
+
+    explicit FunctionModelEvaluate(const ExternalModels & models) : models(models) {}
+
+    String getName() const override { return name; }
+
+    bool isVariadic() const override { return true; }
+
+    size_t getNumberOfArguments() const override { return 0; }
+
+    DataTypePtr getReturnTypeImpl(const DataTypes & arguments) const override;
+
+    void executeImpl(Block & block, const ColumnNumbers & arguments, size_t result) override;
+
+private:
+    const ExternalModels & models;
+};
+
+}

dbms/src/Functions/registerFunctions.cpp

@@ -20,6 +20,7 @@ void registerFunctionsConversion(FunctionFactory &);
 void registerFunctionsDateTime(FunctionFactory &);
 void registerFunctionsEmbeddedDictionaries(FunctionFactory &);
 void registerFunctionsExternalDictionaries(FunctionFactory &);
+void registerFunctionsExternalModels(FunctionFactory &);
 void registerFunctionsFormatting(FunctionFactory &);
 void registerFunctionsHashing(FunctionFactory &);
 void registerFunctionsHigherOrder(FunctionFactory &);
@@ -54,6 +55,7 @@ void registerFunctions()
     registerFunctionsDateTime(factory);
     registerFunctionsEmbeddedDictionaries(factory);
     registerFunctionsExternalDictionaries(factory);
+    registerFunctionsExternalModels(factory);
     registerFunctionsFormatting(factory);
     registerFunctionsHashing(factory);
     registerFunctionsHigherOrder(factory);

dbms/src/Interpreters/Context.cpp

@@ -29,6 +29,7 @@
 #include <Interpreters/Quota.h>
 #include <Interpreters/EmbeddedDictionaries.h>
 #include <Interpreters/ExternalDictionaries.h>
+#include <Interpreters/ExternalModels.h>
 #include <Interpreters/ProcessList.h>
 #include <Interpreters/Cluster.h>
 #include <Interpreters/InterserverIOHandler.h>
@@ -94,6 +95,7 @@ struct ContextShared
     /// Separate mutex for access of dictionaries. Separate mutex to avoid locks when server doing request to itself.
     mutable std::mutex embedded_dictionaries_mutex;
     mutable std::mutex external_dictionaries_mutex;
+    mutable std::mutex external_models_mutex;
     /// Separate mutex for re-initialization of zookeer session. This operation could take a long time and must not interfere with another operations.
     mutable std::mutex zookeeper_mutex;
 
@@ -111,6 +113,7 @@ struct ContextShared
     FormatFactory format_factory;                           /// Formats.
     mutable std::shared_ptr<EmbeddedDictionaries> embedded_dictionaries;    /// Metrica's dictionaeis. Have lazy initialization.
     mutable std::shared_ptr<ExternalDictionaries> external_dictionaries;
+    mutable std::shared_ptr<ExternalModels> external_models;
     String default_profile_name;                            /// Default profile name used for default values.
     Users users;                                            /// Known users.
     Quotas quotas;                                          /// Known quotas for resource use.
@@ -1062,6 +1065,17 @@ ExternalDictionaries & Context::getExternalDictionaries()
 }
 
 
+const ExternalModels & Context::getExternalModels() const
+{
+    return getExternalModelsImpl(false);
+}
+
+ExternalModels & Context::getExternalModels()
+{
+    return getExternalModelsImpl(false);
+}
+
+
 EmbeddedDictionaries & Context::getEmbeddedDictionariesImpl(const bool throw_on_error) const
 {
     std::lock_guard<std::mutex> lock(shared->embedded_dictionaries_mutex);
@@ -1087,6 +1101,19 @@ ExternalDictionaries & Context::getExternalDictionariesImpl(const bool throw_on_
     return *shared->external_dictionaries;
 }
 
+ExternalModels & Context::getExternalModelsImpl(bool throw_on_error) const
+{
+    std::lock_guard<std::mutex> lock(shared->external_models_mutex);
+
+    if (!shared->external_models)
+    {
+        if (!this->global_context)
+            throw Exception("Logical error: there is no global context", ErrorCodes::LOGICAL_ERROR);
+        shared->external_models = std::make_shared<ExternalModels>(*this->global_context, throw_on_error);
+    }
+
+    return *shared->external_models;
+}
 
 void Context::tryCreateEmbeddedDictionaries() const
 {
@@ -1100,6 +1127,12 @@ void Context::tryCreateExternalDictionaries() const
 }
 
 
+void Context::tryCreateExternalModels() const
+{
+    static_cast<void>(getExternalModelsImpl(true));
+}
+
+
 void Context::setProgressCallback(ProgressCallback callback)
 {
     /// Callback is set to a session or to a query. In the session, only one query is processed at a time. Therefore, the lock is not needed.

dbms/src/Interpreters/Context.h

@@ -35,6 +35,7 @@ struct ContextShared;
 class QuotaForIntervals;
 class EmbeddedDictionaries;
 class ExternalDictionaries;
+class ExternalModels;
 class InterserverIOHandler;
 class BackgroundProcessingPool;
 class ReshardingWorker;
@@ -209,10 +210,13 @@ public:
 
     const EmbeddedDictionaries & getEmbeddedDictionaries() const;
     const ExternalDictionaries & getExternalDictionaries() const;
+    const ExternalModels & getExternalModels() const;
     EmbeddedDictionaries & getEmbeddedDictionaries();
     ExternalDictionaries & getExternalDictionaries();
+    ExternalModels & getExternalModels();
     void tryCreateEmbeddedDictionaries() const;
     void tryCreateExternalDictionaries() const;
+    void tryCreateExternalModels() const;
 
     /// I/O formats.
     BlockInputStreamPtr getInputFormat(const String & name, ReadBuffer & buf, const Block & sample, size_t max_block_size) const;
@@ -362,6 +366,7 @@ private:
 
     EmbeddedDictionaries & getEmbeddedDictionariesImpl(bool throw_on_error) const;
     ExternalDictionaries & getExternalDictionariesImpl(bool throw_on_error) const;
+    ExternalModels & getExternalModelsImpl(bool throw_on_error) const;
 
     StoragePtr getTableImpl(const String & database_name, const String & table_name, Exception * exception) const;
 

dbms/src/Interpreters/DictionaryFactory.cpp

@@ -24,7 +24,7 @@ namespace ErrorCodes
 }
 
 
-DictionaryPtr DictionaryFactory::create(const std::string & name, Poco::Util::AbstractConfiguration & config,
+DictionaryPtr DictionaryFactory::create(const std::string & name, const Poco::Util::AbstractConfiguration & config,
     const std::string & config_prefix, Context & context) const
 {
     Poco::Util::AbstractConfiguration::Keys keys;

dbms/src/Interpreters/ExternalDictionaries.cpp

@@ -1,427 +1,46 @@
 #include <Interpreters/ExternalDictionaries.h>
 #include <Interpreters/Context.h>
 #include <Dictionaries/DictionaryFactory.h>
-#include <Dictionaries/DictionaryStructure.h>
-#include <Dictionaries/IDictionarySource.h>
-#include <Common/StringUtils.h>
-#include <Common/MemoryTracker.h>
-#include <Common/getMultipleKeysFromConfig.h>
-#include <ext/scope_guard.h>
-#include <Poco/Util/Application.h>
-#include <Poco/Glob.h>
-#include <Poco/File.h>
-
-
-namespace
-{
-    const auto check_period_sec = 5;
-    const auto backoff_initial_sec = 5;
-    /// 10 minutes
-    const auto backoff_max_sec = 10 * 60;
-}
 
 namespace DB
 {
 
-namespace ErrorCodes
-{
-    extern const int LOGICAL_ERROR;
-    extern const int BAD_ARGUMENTS;
-}
-
-
-void ExternalDictionaries::reloadPeriodically()
-{
-    setThreadName("ExterDictReload");
-
-    while (true)
-    {
-        if (destroy.tryWait(check_period_sec * 1000))
-            return;
-
-        reloadAndUpdate();
-    }
-}
-
-
-ExternalDictionaries::ExternalDictionaries(Context & context, const bool throw_on_error)
-    : context(context), log(&Logger::get("ExternalDictionaries"))
-{
-    {
-        /** During synchronous loading of external dictionaries at moment of query execution,
-            *  we should not use per query memory limit.
-            */
-        TemporarilyDisableMemoryTracker temporarily_disable_memory_tracker;
-
-        reloadAndUpdate(throw_on_error);
-    }
-
-    reloading_thread = std::thread{&ExternalDictionaries::reloadPeriodically, this};
-}
-
-
-ExternalDictionaries::~ExternalDictionaries()
-{
-    destroy.set();
-    reloading_thread.join();
-}
-
 namespace
 {
-std::set<std::string> getDictionariesConfigPaths(const Poco::Util::AbstractConfiguration & config)
+    const ExternalLoaderUpdateSettings externalDictionariesUpdateSettings;
-{
+
-    std::set<std::string> files;
+    const ExternalLoaderConfigSettings & getExternalDictionariesConfigSettings()
-    auto patterns = getMultipleValuesFromConfig(config, "", "dictionaries_config");
-    for (auto & pattern : patterns)
     {
-        if (pattern.empty())
+        static ExternalLoaderConfigSettings settings;
-            continue;
+        static std::once_flag flag;
 
-        if (pattern[0] != '/')
+        std::call_once(flag, [] {
-        {
+            settings.external_config = "dictionary";
-            const auto app_config_path = config.getString("config-file", "config.xml");
+            settings.external_name = "name";
-            const auto config_dir = Poco::Path{app_config_path}.parent().toString();
-            const auto absolute_path = config_dir + pattern;
-            Poco::Glob::glob(absolute_path, files, 0);
-            if (!files.empty())
-                continue;
-        }
 
-        Poco::Glob::glob(pattern, files, 0);
+            settings.path_setting_name = "dictionaries_config";
-    }
+        });
 
-    return files;
+        return settings;
-}
-}
-
-void ExternalDictionaries::reloadAndUpdate(bool throw_on_error)
-{
-    reloadFromConfigFiles(throw_on_error);
-
-    /// list of recreated dictionaries to perform delayed removal from unordered_map
-    std::list<std::string> recreated_failed_dictionaries;
-
-    std::unique_lock<std::mutex> all_lock(all_mutex);
-
-    /// retry loading failed dictionaries
-    for (auto & failed_dictionary : failed_dictionaries)
-    {
-        if (std::chrono::system_clock::now() < failed_dictionary.second.next_attempt_time)
-            continue;
-
-        const auto & name = failed_dictionary.first;
-
-        try
-        {
-            auto dict_ptr = failed_dictionary.second.dict->clone();
-            if (const auto exception_ptr = dict_ptr->getCreationException())
-            {
-                /// recalculate next attempt time
-                std::uniform_int_distribution<UInt64> distribution(
-                        0, static_cast<UInt64>(std::exp2(failed_dictionary.second.error_count)));
-
-                failed_dictionary.second.next_attempt_time = std::chrono::system_clock::now() +
-                    std::chrono::seconds{
-                        std::min<UInt64>(backoff_max_sec, backoff_initial_sec + distribution(rnd_engine))};
-
-                ++failed_dictionary.second.error_count;
-
-                std::rethrow_exception(exception_ptr);
-            }
-            else
-            {
-                const std::lock_guard<std::mutex> lock{dictionaries_mutex};
-
-                const auto & lifetime = dict_ptr->getLifetime();
-                std::uniform_int_distribution<UInt64> distribution{lifetime.min_sec, lifetime.max_sec};
-                update_times[name] = std::chrono::system_clock::now() + std::chrono::seconds{distribution(rnd_engine)};
-
-                const auto dict_it = dictionaries.find(name);
-                if (dict_it->second.dict)
-                    dict_it->second.dict->set(dict_ptr.release());
-                else
-                    dict_it->second.dict = std::make_shared<MultiVersion<IDictionaryBase>>(dict_ptr.release());
-
-                /// clear stored exception on success
-                dict_it->second.exception = std::exception_ptr{};
-
-                recreated_failed_dictionaries.push_back(name);
-            }
-        }
-        catch (...)
-        {
-            tryLogCurrentException(log, "Failed reloading '" + name + "' dictionary");
-
-            if (throw_on_error)
-                throw;
-        }
-    }
-
-    /// do not undertake further attempts to recreate these dictionaries
-    for (const auto & name : recreated_failed_dictionaries)
-        failed_dictionaries.erase(name);
-
-    /// periodic update
-    for (auto & dictionary : dictionaries)
-    {
-        const auto & name = dictionary.first;
-
-        try
-        {
-            /// If the dictionary failed to load or even failed to initialize from the config.
-            if (!dictionary.second.dict)
-                continue;
-
-            auto current = dictionary.second.dict->get();
-            const auto & lifetime = current->getLifetime();
-
-            /// do not update dictionaries with zero as lifetime
-            if (lifetime.min_sec == 0 || lifetime.max_sec == 0)
-                continue;
-
-            /// update only non-cached dictionaries
-            if (!current->isCached())
-            {
-                auto & update_time = update_times[current->getName()];
-
-                /// check that timeout has passed
-                if (std::chrono::system_clock::now() < update_time)
-                    continue;
-
-                SCOPE_EXIT({
-                    /// calculate next update time
-                    std::uniform_int_distribution<UInt64> distribution{lifetime.min_sec, lifetime.max_sec};
-                    update_time = std::chrono::system_clock::now() + std::chrono::seconds{distribution(rnd_engine)};
-                });
-
-                /// check source modified
-                if (current->getSource()->isModified())
-                {
-                    /// create new version of dictionary
-                    auto new_version = current->clone();
-
-                    if (const auto exception_ptr = new_version->getCreationException())
-                        std::rethrow_exception(exception_ptr);
-
-                    dictionary.second.dict->set(new_version.release());
-                }
-            }
-
-            /// erase stored exception on success
-            dictionary.second.exception = std::exception_ptr{};
-        }
-        catch (...)
-        {
-            dictionary.second.exception = std::current_exception();
-
-            tryLogCurrentException(log, "Cannot update external dictionary '" + name + "', leaving old version");
-
-            if (throw_on_error)
-                throw;
-        }
     }
 }
 
-void ExternalDictionaries::reloadFromConfigFiles(const bool throw_on_error, const bool force_reload, const std::string & only_dictionary)
+
+ExternalDictionaries::ExternalDictionaries(Context & context, bool throw_on_error)
+        : ExternalLoader(context.getConfigRef(),
+                         externalDictionariesUpdateSettings,
+                         getExternalDictionariesConfigSettings(),
+                         &Logger::get("ExternalDictionaries"),
+                         "external dictionary"),
+          context(context)
 {
-    const auto config_paths = getDictionariesConfigPaths(context.getConfigRef());
+    init(throw_on_error);
-
-    for (const auto & config_path : config_paths)
-    {
-        try
-        {
-            reloadFromConfigFile(config_path, throw_on_error, force_reload, only_dictionary);
-        }
-        catch (...)
-        {
-            tryLogCurrentException(log, "reloadFromConfigFile has thrown while reading from " + config_path);
-
-            if (throw_on_error)
-                throw;
-        }
-    }
 }
 
-void ExternalDictionaries::reloadFromConfigFile(const std::string & config_path, const bool throw_on_error, const bool force_reload,
+std::unique_ptr<IExternalLoadable> ExternalDictionaries::create(
-                                                const std::string & only_dictionary)
+        const std::string & name, const Configuration & config, const std::string & config_prefix)
 {
-    const Poco::File config_file{config_path};
+    return DictionaryFactory::instance().create(name, config, config_prefix, context);
-
-    if (config_path.empty() || !config_file.exists())
-    {
-        LOG_WARNING(log, "config file '" + config_path + "' does not exist");
-    }
-    else
-    {
-        std::unique_lock<std::mutex> all_lock(all_mutex);
-
-        auto modification_time_it = last_modification_times.find(config_path);
-        if (modification_time_it == std::end(last_modification_times))
-            modification_time_it = last_modification_times.emplace(config_path, Poco::Timestamp{0}).first;
-        auto & config_last_modified = modification_time_it->second;
-
-        const auto last_modified = config_file.getLastModified();
-        if (force_reload || last_modified > config_last_modified)
-        {
-            Poco::AutoPtr<Poco::Util::XMLConfiguration> config = new Poco::Util::XMLConfiguration(config_path);
-
-            /// Definitions of dictionaries may have changed, recreate all of them
-
-            /// If we need update only one dictionary, don't update modification time: might be other dictionaries in the config file
-            if (only_dictionary.empty())
-                config_last_modified = last_modified;
-
-            /// get all dictionaries' definitions
-            Poco::Util::AbstractConfiguration::Keys keys;
-            config->keys(keys);
-
-            /// for each dictionary defined in xml config
-            for (const auto & key : keys)
-            {
-                std::string name;
-
-                if (!startsWith(key, "dictionary"))
-                {
-                    if (!startsWith(key.data(), "comment"))
-                        LOG_WARNING(log,
-                            config_path << ": unknown node in dictionaries file: '" << key + "', 'dictionary'");
-
-                    continue;
-                }
-
-                try
-                {
-                    name = config->getString(key + ".name");
-                    if (name.empty())
-                    {
-                        LOG_WARNING(log, config_path << ": dictionary name cannot be empty");
-                        continue;
-                    }
-
-                    if (!only_dictionary.empty() && name != only_dictionary)
-                        continue;
-
-                    decltype(dictionaries.begin()) dict_it;
-                    {
-                        std::lock_guard<std::mutex> lock{dictionaries_mutex};
-                        dict_it = dictionaries.find(name);
-                    }
-
-                    if (dict_it != std::end(dictionaries) && dict_it->second.origin != config_path)
-                        throw std::runtime_error{"Overriding dictionary from file " + dict_it->second.origin};
-
-                    auto dict_ptr = DictionaryFactory::instance().create(name, *config, key, context);
-
-                    /// If the dictionary could not be loaded.
-                    if (const auto exception_ptr = dict_ptr->getCreationException())
-                    {
-                        const auto failed_dict_it = failed_dictionaries.find(name);
-                        if (failed_dict_it != std::end(failed_dictionaries))
-                        {
-                            failed_dict_it->second = FailedDictionaryInfo{
-                                std::move(dict_ptr),
-                                std::chrono::system_clock::now() + std::chrono::seconds{backoff_initial_sec}};
-                        }
-                        else
-                            failed_dictionaries.emplace(name, FailedDictionaryInfo{
-                                std::move(dict_ptr),
-                                std::chrono::system_clock::now() + std::chrono::seconds{backoff_initial_sec}});
-
-                        std::rethrow_exception(exception_ptr);
-                    }
-                    else if (!dict_ptr->isCached())
-                    {
-                        const auto & lifetime = dict_ptr->getLifetime();
-                        if (lifetime.min_sec != 0 && lifetime.max_sec != 0)
-                        {
-                            std::uniform_int_distribution<UInt64> distribution{
-                                lifetime.min_sec,
-                                lifetime.max_sec
-                            };
-                            update_times[name] = std::chrono::system_clock::now() +
-                                std::chrono::seconds{distribution(rnd_engine)};
-                        }
-                    }
-
-                    const std::lock_guard<std::mutex> lock{dictionaries_mutex};
-
-                    /// add new dictionary or update an existing version
-                    if (dict_it == std::end(dictionaries))
-                        dictionaries.emplace(name, DictionaryInfo{
-                            std::make_shared<MultiVersion<IDictionaryBase>>(dict_ptr.release()),
-                            config_path
-                        });
-                    else
-                    {
-                        if (dict_it->second.dict)
-                            dict_it->second.dict->set(dict_ptr.release());
-                        else
-                            dict_it->second.dict = std::make_shared<MultiVersion<IDictionaryBase>>(dict_ptr.release());
-
-                        /// erase stored exception on success
-                        dict_it->second.exception = std::exception_ptr{};
-                        failed_dictionaries.erase(name);
-                    }
-                }
-                catch (...)
-                {
-                    if (!name.empty())
-                    {
-                        /// If the dictionary could not load data or even failed to initialize from the config.
-                        /// - all the same we insert information into the `dictionaries`, with the zero pointer `dict`.
-
-                        const std::lock_guard<std::mutex> lock{dictionaries_mutex};
-
-                        const auto exception_ptr = std::current_exception();
-                        const auto dict_it = dictionaries.find(name);
-                        if (dict_it == std::end(dictionaries))
-                            dictionaries.emplace(name, DictionaryInfo{nullptr, config_path, exception_ptr});
-                        else
-                            dict_it->second.exception = exception_ptr;
-                    }
-
-                    tryLogCurrentException(log, "Cannot create external dictionary '" + name + "' from config path " + config_path);
-
-                    /// propagate exception
-                    if (throw_on_error)
-                        throw;
-                }
-            }
-        }
-    }
-}
-
-void ExternalDictionaries::reload()
-{
-    reloadFromConfigFiles(true, true);
-}
-
-void ExternalDictionaries::reloadDictionary(const std::string & name)
-{
-    reloadFromConfigFiles(true, true, name);
-
-    /// Check that specified dict was loaded
-    const std::lock_guard<std::mutex> lock{dictionaries_mutex};
-    if (!dictionaries.count(name))
-        throw Exception("Dictionary " + name + " wasn't loaded during the reload process", ErrorCodes::BAD_ARGUMENTS);
-}
-
-MultiVersion<IDictionaryBase>::Version ExternalDictionaries::getDictionary(const std::string & name) const
-{
-    const std::lock_guard<std::mutex> lock{dictionaries_mutex};
-
-    const auto it = dictionaries.find(name);
-    if (it == std::end(dictionaries))
-        throw Exception{
-            "No such dictionary: " + name,
-            ErrorCodes::BAD_ARGUMENTS
-        };
-
-    if (!it->second.dict)
-        it->second.exception ? std::rethrow_exception(it->second.exception) :
-            throw Exception{"No dictionary", ErrorCodes::LOGICAL_ERROR};
-
-    return it->second.dict->get();
 }
 
 }

dbms/src/Interpreters/ExternalDictionaries.h

@@ -1,19 +1,9 @@
 #pragma once
 
 #include <Dictionaries/IDictionary.h>
-#include <Common/Exception.h>
+#include <Interpreters/ExternalLoader.h>
-#include <Common/setThreadName.h>
-#include <Common/randomSeed.h>
-#include <common/MultiVersion.h>
 #include <common/logger_useful.h>
-#include <Poco/Event.h>
+#include <memory>
-#include <unistd.h>
-#include <time.h>
-#include <mutex>
-#include <thread>
-#include <unordered_map>
-#include <chrono>
-#include <pcg_random.hpp>
 
 
 namespace DB
@@ -21,93 +11,36 @@ namespace DB
 
 class Context;
 
-/** Manages user-defined dictionaries.
+/// Manages user-defined dictionaries.
-*    Monitors configuration file and automatically reloads dictionaries in a separate thread.
+class ExternalDictionaries : public ExternalLoader
-*    The monitoring thread wakes up every @check_period_sec seconds and checks
-*    modification time of dictionaries' configuration file. If said time is greater than
-*    @config_last_modified, the dictionaries are created from scratch using configuration file,
-*    possibly overriding currently existing dictionaries with the same name (previous versions of
-*    overridden dictionaries will live as long as there are any users retaining them).
-*
-*    Apart from checking configuration file for modifications, each non-cached dictionary
-*    has a lifetime of its own and may be updated if it's source reports that it has been
-*    modified. The time of next update is calculated by choosing uniformly a random number
-*    distributed between lifetime.min_sec and lifetime.max_sec.
-*    If either of lifetime.min_sec and lifetime.max_sec is zero, such dictionary is never updated.
-*/
-class ExternalDictionaries
 {
-private:
+public:
+    using DictPtr = std::shared_ptr<IDictionaryBase>;
+
+    /// Dictionaries will be loaded immediately and then will be updated in separate thread, each 'reload_period' seconds.
+    ExternalDictionaries(Context & context, bool throw_on_error);
+
+    /// Forcibly reloads specified dictionary.
+    void reloadDictionary(const std::string & name) { reload(name); }
+
+    DictPtr getDictionary(const std::string & name) const
+    {
+        return std::static_pointer_cast<IDictionaryBase>(getLoadable(name));
+    }
+
+protected:
+
+    std::unique_ptr<IExternalLoadable> create(const std::string & name, const Configuration & config,
+                                              const std::string & config_prefix) override;
+
+    using ExternalLoader::getObjectsMap;
+
     friend class StorageSystemDictionaries;
     friend class DatabaseDictionary;
 
-    /// Protects only dictionaries map.
+private:
-    mutable std::mutex dictionaries_mutex;
-
-    /// Protects all data, currently used to avoid races between updating thread and SYSTEM queries
-    mutable std::mutex all_mutex;
-
-    using DictionaryPtr = std::shared_ptr<MultiVersion<IDictionaryBase>>;
-    struct DictionaryInfo final
-    {
-        DictionaryPtr dict;
-        std::string origin;
-        std::exception_ptr exception;
-    };
-
-    struct FailedDictionaryInfo final
-    {
-        std::unique_ptr<IDictionaryBase> dict;
-        std::chrono::system_clock::time_point next_attempt_time;
-        UInt64 error_count;
-    };
-
-    /** name -> dictionary.
-      */
-    std::unordered_map<std::string, DictionaryInfo> dictionaries;
-
-    /** Here are dictionaries, that has been never loaded successfully.
-      * They are also in 'dictionaries', but with nullptr as 'dict'.
-      */
-    std::unordered_map<std::string, FailedDictionaryInfo> failed_dictionaries;
-
-    /** Both for dictionaries and failed_dictionaries.
-      */
-    std::unordered_map<std::string, std::chrono::system_clock::time_point> update_times;
-
-    pcg64 rnd_engine{randomSeed()};
 
     Context & context;
-
-    std::thread reloading_thread;
-    Poco::Event destroy;
-
-    Logger * log;
-
-    std::unordered_map<std::string, Poco::Timestamp> last_modification_times;
-
-    /// Check dictionaries definitions in config files and reload or/and add new ones if the definition is changed
-    void reloadFromConfigFiles(const bool throw_on_error, const bool force_reload = false, const std::string & only_dictionary = "");
-    void reloadFromConfigFile(const std::string & config_path, const bool throw_on_error, const bool force_reload,
-                                  const std::string & only_dictionary);
-
-    /// Check config files and update expired dictionaries
-    void reloadAndUpdate(bool throw_on_error = false);
-
-    void reloadPeriodically();
-
-public:
-    /// Dictionaries will be loaded immediately and then will be updated in separate thread, each 'reload_period' seconds.
-    ExternalDictionaries(Context & context, const bool throw_on_error);
-    ~ExternalDictionaries();
-
-    /// Forcibly reloads all dictionaries.
-    void reload();
-
-    /// Forcibly reloads specified dictionary.
-    void reloadDictionary(const std::string & name);
-
-    MultiVersion<IDictionaryBase>::Version getDictionary(const std::string & name) const;
 };
 
 }

dbms/src/Interpreters/ExternalLoader.cpp

@@ -0,0 +1,433 @@
+#include <Interpreters/ExternalLoader.h>
+#include <Common/StringUtils.h>
+#include <Common/MemoryTracker.h>
+#include <Common/Exception.h>
+#include <Common/getMultipleKeysFromConfig.h>
+#include <Common/setThreadName.h>
+#include <ext/scope_guard.h>
+#include <Poco/Util/Application.h>
+#include <Poco/Glob.h>
+#include <Poco/File.h>
+#include <cmath>
+#include <Poco/Util/XMLConfiguration.h>
+
+namespace DB
+{
+
+namespace ErrorCodes
+{
+extern const int LOGICAL_ERROR;
+extern const int BAD_ARGUMENTS;
+}
+
+
+ExternalLoadableLifetime::ExternalLoadableLifetime(const Poco::Util::AbstractConfiguration & config,
+                                                   const std::string & config_prefix)
+{
+    const auto & lifetime_min_key = config_prefix + ".min";
+    const auto has_min = config.has(lifetime_min_key);
+
+    min_sec = has_min ? config.getUInt64(lifetime_min_key) : config.getUInt64(config_prefix);
+    max_sec = has_min ? config.getUInt64(config_prefix + ".max") : min_sec;
+}
+
+void ExternalLoader::reloadPeriodically()
+{
+    setThreadName("ExterLdrReload");
+
+    while (true)
+    {
+        if (destroy.tryWait(update_settings.check_period_sec * 1000))
+            return;
+
+        reloadAndUpdate();
+    }
+}
+
+
+ExternalLoader::ExternalLoader(const Poco::Util::AbstractConfiguration & config,
+                               const ExternalLoaderUpdateSettings & update_settings,
+                               const ExternalLoaderConfigSettings & config_settings,
+                               Logger * log, const std::string & loadable_object_name)
+        : config(config), update_settings(update_settings), config_settings(config_settings),
+          log(log), object_name(loadable_object_name)
+{
+}
+
+void ExternalLoader::init(bool throw_on_error)
+{
+    if (is_initialized)
+        return;
+
+    is_initialized = true;
+
+    {
+        /// During synchronous loading of external dictionaries at moment of query execution,
+        /// we should not use per query memory limit.
+        TemporarilyDisableMemoryTracker temporarily_disable_memory_tracker;
+
+        reloadAndUpdate(throw_on_error);
+    }
+
+    reloading_thread = std::thread{&ExternalLoader::reloadPeriodically, this};
+}
+
+
+ExternalLoader::~ExternalLoader()
+{
+    destroy.set();
+    reloading_thread.join();
+}
+
+namespace
+{
+std::set<std::string> getConfigPaths(const Poco::Util::AbstractConfiguration & config,
+                                     const std::string & external_config_paths_setting)
+{
+    std::set<std::string> files;
+    auto patterns = getMultipleValuesFromConfig(config, "", external_config_paths_setting);
+    for (auto & pattern : patterns)
+    {
+        if (pattern.empty())
+            continue;
+
+        if (pattern[0] != '/')
+        {
+            const auto app_config_path = config.getString("config-file", "config.xml");
+            const auto config_dir = Poco::Path{app_config_path}.parent().toString();
+            const auto absolute_path = config_dir + pattern;
+            Poco::Glob::glob(absolute_path, files, 0);
+            if (!files.empty())
+                continue;
+        }
+
+        Poco::Glob::glob(pattern, files, 0);
+    }
+
+    return files;
+}
+}
+
+void ExternalLoader::reloadAndUpdate(bool throw_on_error)
+{
+    reloadFromConfigFiles(throw_on_error);
+
+    /// list of recreated loadable objects to perform delayed removal from unordered_map
+    std::list<std::string> recreated_failed_loadable_objects;
+
+    std::unique_lock<std::mutex> all_lock(all_mutex);
+
+    /// retry loading failed loadable objects
+    for (auto & failed_loadable_object : failed_loadable_objects)
+    {
+        if (std::chrono::system_clock::now() < failed_loadable_object.second.next_attempt_time)
+            continue;
+
+        const auto & name = failed_loadable_object.first;
+
+        try
+        {
+            auto loadable_ptr = failed_loadable_object.second.loadable->clone();
+            if (const auto exception_ptr = loadable_ptr->getCreationException())
+            {
+                /// recalculate next attempt time
+                std::uniform_int_distribution<UInt64> distribution(
+                        0, static_cast<UInt64>(std::exp2(failed_loadable_object.second.error_count)));
+
+                std::chrono::seconds delay(std::min<UInt64>(
+                        update_settings.backoff_max_sec,
+                        update_settings.backoff_initial_sec + distribution(rnd_engine)));
+                failed_loadable_object.second.next_attempt_time = std::chrono::system_clock::now() + delay;
+
+                ++failed_loadable_object.second.error_count;
+
+                std::rethrow_exception(exception_ptr);
+            }
+            else
+            {
+                const std::lock_guard<std::mutex> lock{map_mutex};
+
+                const auto & lifetime = loadable_ptr->getLifetime();
+                std::uniform_int_distribution<UInt64> distribution{lifetime.min_sec, lifetime.max_sec};
+                update_times[name] = std::chrono::system_clock::now() + std::chrono::seconds{distribution(rnd_engine)};
+
+                const auto dict_it = loadable_objects.find(name);
+
+                dict_it->second.loadable.reset();
+                dict_it->second.loadable = std::move(loadable_ptr);
+
+                /// clear stored exception on success
+                dict_it->second.exception = std::exception_ptr{};
+
+                recreated_failed_loadable_objects.push_back(name);
+            }
+        }
+        catch (...)
+        {
+            tryLogCurrentException(log, "Failed reloading '" + name + "' " + object_name);
+
+            if (throw_on_error)
+                throw;
+        }
+    }
+
+    /// do not undertake further attempts to recreate these loadable objects
+    for (const auto & name : recreated_failed_loadable_objects)
+        failed_loadable_objects.erase(name);
+
+    /// periodic update
+    for (auto & loadable_object : loadable_objects)
+    {
+        const auto & name = loadable_object.first;
+
+        try
+        {
+            /// If the loadable objects failed to load or even failed to initialize from the config.
+            if (!loadable_object.second.loadable)
+                continue;
+
+            auto current = loadable_object.second.loadable;
+            const auto & lifetime = current->getLifetime();
+
+            /// do not update loadable objects with zero as lifetime
+            if (lifetime.min_sec == 0 || lifetime.max_sec == 0)
+                continue;
+
+            if (current->supportUpdates())
+            {
+                auto & update_time = update_times[current->getName()];
+
+                /// check that timeout has passed
+                if (std::chrono::system_clock::now() < update_time)
+                    continue;
+
+                SCOPE_EXIT({
+                        /// calculate next update time
+                        std::uniform_int_distribution<UInt64> distribution{lifetime.min_sec, lifetime.max_sec};
+                        update_time = std::chrono::system_clock::now() + std::chrono::seconds{distribution(rnd_engine)};
+                           });
+
+                /// check source modified
+                if (current->isModified())
+                {
+                    /// create new version of loadable object
+                    auto new_version = current->clone();
+
+                    if (const auto exception_ptr = new_version->getCreationException())
+                        std::rethrow_exception(exception_ptr);
+
+                    loadable_object.second.loadable.reset();
+                    loadable_object.second.loadable = std::move(new_version);
+                }
+            }
+
+            /// erase stored exception on success
+            loadable_object.second.exception = std::exception_ptr{};
+        }
+        catch (...)
+        {
+            loadable_object.second.exception = std::current_exception();
+
+            tryLogCurrentException(log, "Cannot update " + object_name + " '" + name + "', leaving old version");
+
+            if (throw_on_error)
+                throw;
+        }
+    }
+}
+
+void ExternalLoader::reloadFromConfigFiles(const bool throw_on_error, const bool force_reload, const std::string & only_dictionary)
+{
+    const auto config_paths = getConfigPaths(config, config_settings.path_setting_name);
+
+    for (const auto & config_path : config_paths)
+    {
+        try
+        {
+            reloadFromConfigFile(config_path, throw_on_error, force_reload, only_dictionary);
+        }
+        catch (...)
+        {
+            tryLogCurrentException(log, "reloadFromConfigFile has thrown while reading from " + config_path);
+
+            if (throw_on_error)
+                throw;
+        }
+    }
+}
+
+void ExternalLoader::reloadFromConfigFile(const std::string & config_path, const bool throw_on_error,
+                                          const bool force_reload, const std::string & loadable_name)
+{
+    const Poco::File config_file{config_path};
+
+    if (config_path.empty() || !config_file.exists())
+    {
+        LOG_WARNING(log, "config file '" + config_path + "' does not exist");
+    }
+    else
+    {
+        std::unique_lock<std::mutex> all_lock(all_mutex);
+
+        auto modification_time_it = last_modification_times.find(config_path);
+        if (modification_time_it == std::end(last_modification_times))
+            modification_time_it = last_modification_times.emplace(config_path, Poco::Timestamp{0}).first;
+        auto & config_last_modified = modification_time_it->second;
+
+        const auto last_modified = config_file.getLastModified();
+        if (force_reload || last_modified > config_last_modified)
+        {
+            Poco::AutoPtr<Poco::Util::XMLConfiguration> config = new Poco::Util::XMLConfiguration(config_path);
+
+            /// Definitions of loadable objects may have changed, recreate all of them
+
+            /// If we need update only one object, don't update modification time: might be other objects in the config file
+            if (loadable_name.empty())
+                config_last_modified = last_modified;
+
+            /// get all objects' definitions
+            Poco::Util::AbstractConfiguration::Keys keys;
+            config->keys(keys);
+
+            /// for each loadable object defined in xml config
+            for (const auto & key : keys)
+            {
+                std::string name;
+
+                if (!startsWith(key, config_settings.external_config))
+                {
+                    if (!startsWith(key, "comment"))
+                        LOG_WARNING(log, config_path << ": unknown node in file: '" << key
+                                                     << "', expected '" << config_settings.external_config << "'");
+                    continue;
+                }
+
+                try
+                {
+                    name = config->getString(key + "." + config_settings.external_name);
+                    if (name.empty())
+                    {
+                        LOG_WARNING(log, config_path << ": " + config_settings.external_name + " name cannot be empty");
+                        continue;
+                    }
+
+                    if (!loadable_name.empty() && name != loadable_name)
+                        continue;
+
+                    decltype(loadable_objects.begin()) object_it;
+                    {
+                        std::lock_guard<std::mutex> lock{map_mutex};
+                        object_it = loadable_objects.find(name);
+                    }
+
+                    if (object_it != std::end(loadable_objects) && object_it->second.origin != config_path)
+                        throw std::runtime_error{"Overriding " + object_name + " from file " + object_it->second.origin};
+
+                    auto object_ptr = create(name, *config, key);
+
+                    /// If the object could not be loaded.
+                    if (const auto exception_ptr = object_ptr->getCreationException())
+                    {
+                        std::chrono::seconds delay(update_settings.backoff_initial_sec);
+                        const auto failed_dict_it = failed_loadable_objects.find(name);
+                        FailedLoadableInfo info{std::move(object_ptr), std::chrono::system_clock::now() + delay, 0};
+                        if (failed_dict_it != std::end(failed_loadable_objects))
+                            (*failed_dict_it).second = std::move(info);
+                        else
+                            failed_loadable_objects.emplace(name, std::move(info));
+
+                        std::rethrow_exception(exception_ptr);
+                    }
+                    else if (object_ptr->supportUpdates())
+                    {
+                        const auto & lifetime = object_ptr->getLifetime();
+                        if (lifetime.min_sec != 0 && lifetime.max_sec != 0)
+                        {
+                            std::uniform_int_distribution<UInt64> distribution(lifetime.min_sec, lifetime.max_sec);
+
+                            update_times[name] = std::chrono::system_clock::now() +
+                                                 std::chrono::seconds{distribution(rnd_engine)};
+                        }
+                    }
+
+                    const std::lock_guard<std::mutex> lock{map_mutex};
+
+                    /// add new loadable object or update an existing version
+                    if (object_it == std::end(loadable_objects))
+                        loadable_objects.emplace(name, LoadableInfo{std::move(object_ptr), config_path});
+                    else
+                    {
+                        if (object_it->second.loadable)
+                            object_it->second.loadable.reset();
+                        object_it->second.loadable = std::move(object_ptr);
+
+                        /// erase stored exception on success
+                        object_it->second.exception = std::exception_ptr{};
+                        failed_loadable_objects.erase(name);
+                    }
+                }
+                catch (...)
+                {
+                    if (!name.empty())
+                    {
+                        /// If the loadable object could not load data or even failed to initialize from the config.
+                        /// - all the same we insert information into the `loadable_objects`, with the zero pointer `loadable`.
+
+                        const std::lock_guard<std::mutex> lock{map_mutex};
+
+                        const auto exception_ptr = std::current_exception();
+                        const auto loadable_it = loadable_objects.find(name);
+                        if (loadable_it == std::end(loadable_objects))
+                            loadable_objects.emplace(name, LoadableInfo{nullptr, config_path, exception_ptr});
+                        else
+                            loadable_it->second.exception = exception_ptr;
+                    }
+
+                    tryLogCurrentException(log, "Cannot create " + object_name + " '"
+                                                + name + "' from config path " + config_path);
+
+                    /// propagate exception
+                    if (throw_on_error)
+                        throw;
+                }
+            }
+        }
+    }
+}
+
+void ExternalLoader::reload()
+{
+    reloadFromConfigFiles(true, true);
+}
+
+void ExternalLoader::reload(const std::string & name)
+{
+    reloadFromConfigFiles(true, true, name);
+
+    /// Check that specified object was loaded
+    const std::lock_guard<std::mutex> lock{map_mutex};
+    if (!loadable_objects.count(name))
+        throw Exception("Failed to load " + object_name + " '" + name + "' during the reload process", ErrorCodes::BAD_ARGUMENTS);
+}
+
+ExternalLoader::LoadablePtr ExternalLoader::getLoadable(const std::string & name) const
+{
+    const std::lock_guard<std::mutex> lock{map_mutex};
+
+    const auto it = loadable_objects.find(name);
+    if (it == std::end(loadable_objects))
+        throw Exception("No such " + object_name + ": " + name, ErrorCodes::BAD_ARGUMENTS);
+
+    if (!it->second.loadable)
+        it->second.exception ? std::rethrow_exception(it->second.exception) :
+        throw Exception{object_name + " '" + name + "' is not loaded", ErrorCodes::LOGICAL_ERROR};
+
+    return it->second.loadable;
+}
+
+ExternalLoader::LockedObjectsMap ExternalLoader::getObjectsMap() const
+{
+    return LockedObjectsMap(map_mutex, loadable_objects);
+}
+
+}

dbms/src/Interpreters/ExternalLoader.h

@@ -0,0 +1,173 @@
+#pragma once
+
+#include <common/logger_useful.h>
+#include <Poco/Event.h>
+#include <mutex>
+#include <thread>
+#include <unordered_map>
+#include <chrono>
+#include <tuple>
+#include <Interpreters/IExternalLoadable.h>
+#include <Core/Types.h>
+#include <pcg_random.hpp>
+#include <Common/randomSeed.h>
+
+
+namespace DB
+{
+
+class Context;
+
+struct ExternalLoaderUpdateSettings
+{
+    UInt64 check_period_sec = 5;
+    UInt64 backoff_initial_sec = 5;
+    /// 10 minutes
+    UInt64 backoff_max_sec = 10 * 60;
+
+    ExternalLoaderUpdateSettings() = default;
+    ExternalLoaderUpdateSettings(UInt64 check_period_sec, UInt64 backoff_initial_sec, UInt64 backoff_max_sec)
+            : check_period_sec(check_period_sec),
+              backoff_initial_sec(backoff_initial_sec),
+              backoff_max_sec(backoff_max_sec) {}
+};
+
+
+/* External configuration structure.
+ *
+ * <external_group>
+ *     <external_config>
+ *         <external_name>name</external_name>
+ *         ....
+ *     </external_config>
+ * </external_group>
+ */
+struct ExternalLoaderConfigSettings
+{
+    std::string external_config;
+    std::string external_name;
+
+    std::string path_setting_name;
+};
+
+/** Manages user-defined objects.
+*    Monitors configuration file and automatically reloads objects in a separate thread.
+*    The monitoring thread wakes up every @check_period_sec seconds and checks
+*    modification time of objects' configuration file. If said time is greater than
+*    @config_last_modified, the objects are created from scratch using configuration file,
+*    possibly overriding currently existing objects with the same name (previous versions of
+*    overridden objects will live as long as there are any users retaining them).
+*
+*    Apart from checking configuration file for modifications, each object
+*    has a lifetime of its own and may be updated if it supportUpdates.
+*    The time of next update is calculated by choosing uniformly a random number
+*    distributed between lifetime.min_sec and lifetime.max_sec.
+*    If either of lifetime.min_sec and lifetime.max_sec is zero, such object is never updated.
+*/
+class ExternalLoader
+{
+public:
+    using LoadablePtr = std::shared_ptr<IExternalLoadable>;
+
+private:
+    struct LoadableInfo final
+    {
+        LoadablePtr loadable;
+        std::string origin;
+        std::exception_ptr exception;
+    };
+
+    struct FailedLoadableInfo final
+    {
+        std::unique_ptr<IExternalLoadable> loadable;
+        std::chrono::system_clock::time_point next_attempt_time;
+        UInt64 error_count;
+    };
+
+public:
+    using Configuration = Poco::Util::AbstractConfiguration;
+    using ObjectsMap = std::unordered_map<std::string, LoadableInfo>;
+
+    /// Objects will be loaded immediately and then will be updated in separate thread, each 'reload_period' seconds.
+    ExternalLoader(const Configuration & config,
+                   const ExternalLoaderUpdateSettings & update_settings,
+                   const ExternalLoaderConfigSettings & config_settings,
+                   Logger * log, const std::string & loadable_object_name);
+    virtual ~ExternalLoader();
+
+    /// Forcibly reloads all loadable objects.
+    void reload();
+
+    /// Forcibly reloads specified loadable object.
+    void reload(const std::string & name);
+
+    LoadablePtr getLoadable(const std::string & name) const;
+
+protected:
+    virtual std::unique_ptr<IExternalLoadable> create(const std::string & name, const Configuration & config,
+                                                      const std::string & config_prefix) = 0;
+
+    class LockedObjectsMap
+    {
+    public:
+        LockedObjectsMap(std::mutex & mutex, const ObjectsMap & objectsMap) : lock(mutex), objectsMap(objectsMap) {}
+        const ObjectsMap & get() { return objectsMap; }
+    private:
+        std::unique_lock<std::mutex> lock;
+        const ObjectsMap & objectsMap;
+    };
+
+    /// Direct access to objects.
+    LockedObjectsMap getObjectsMap() const;
+
+    /// Should be called in derived constructor (to avoid pure virtual call).
+    void init(bool throw_on_error);
+
+private:
+
+    bool is_initialized = false;
+
+    /// Protects only objects map.
+    mutable std::mutex map_mutex;
+
+    /// Protects all data, currently used to avoid races between updating thread and SYSTEM queries
+    mutable std::mutex all_mutex;
+
+    /// name -> loadable.
+    ObjectsMap loadable_objects;
+
+    /// Here are loadable objects, that has been never loaded successfully.
+    /// They are also in 'loadable_objects', but with nullptr as 'loadable'.
+    std::unordered_map<std::string, FailedLoadableInfo> failed_loadable_objects;
+
+    /// Both for loadable_objects and failed_loadable_objects.
+    std::unordered_map<std::string, std::chrono::system_clock::time_point> update_times;
+
+    pcg64 rnd_engine{randomSeed()};
+
+    const Configuration & config;
+    const ExternalLoaderUpdateSettings & update_settings;
+    const ExternalLoaderConfigSettings & config_settings;
+
+    std::thread reloading_thread;
+    Poco::Event destroy;
+
+    Logger * log;
+    /// Loadable object name to use in log messages.
+    std::string object_name;
+
+    std::unordered_map<std::string, Poco::Timestamp> last_modification_times;
+
+    /// Check objects definitions in config files and reload or/and add new ones if the definition is changed
+    /// If loadable_name is not empty, load only loadable object with name loadable_name
+    void reloadFromConfigFiles(bool throw_on_error, bool force_reload = false, const std::string & loadable_name = "");
+    void reloadFromConfigFile(const std::string & config_path, bool throw_on_error, bool force_reload,
+                              const std::string & loadable_name);
+
+    /// Check config files and update expired loadable objects
+    void reloadAndUpdate(bool throw_on_error = false);
+
+    void reloadPeriodically();
+};
+
+}

dbms/src/Interpreters/ExternalModels.cpp

@@ -0,0 +1,67 @@
+#include <Interpreters/ExternalModels.h>
+#include <Interpreters/Context.h>
+
+namespace DB
+{
+
+namespace ErrorCodes
+{
+    extern const int INVALID_CONFIG_PARAMETER;
+}
+
+namespace
+{
+
+    const ExternalLoaderUpdateSettings externalModelsUpdateSettings;
+
+    const ExternalLoaderConfigSettings & getExternalModelsConfigSettings()
+    {
+        static ExternalLoaderConfigSettings settings;
+        static std::once_flag flag;
+
+        std::call_once(flag, [] {
+            settings.external_config = "model";
+            settings.external_name = "name";
+
+            settings.path_setting_name = "models_config";
+        });
+
+        return settings;
+    }
+}
+
+
+ExternalModels::ExternalModels(Context & context, bool throw_on_error)
+        : ExternalLoader(context.getConfigRef(),
+                         externalModelsUpdateSettings,
+                         getExternalModelsConfigSettings(),
+                         &Logger::get("ExternalModels"),
+                         "external model"),
+          context(context)
+{
+    init(throw_on_error);
+}
+
+std::unique_ptr<IExternalLoadable> ExternalModels::create(
+        const std::string & name, const Configuration & config, const std::string & config_prefix)
+{
+    String type = config.getString(config_prefix + ".type");
+    ExternalLoadableLifetime lifetime(config, config_prefix + ".lifetime");
+
+    /// TODO: add models factory.
+    if (type == "catboost")
+    {
+        return std::make_unique<CatBoostModel>(
+                name, config.getString(config_prefix + ".path"),
+                context.getConfigRef().getString("catboost_dynamic_library_path"),
+                lifetime, config.getUInt(config_prefix + ".float_features_count"),
+                config.getUInt(config_prefix + ".cat_features_count")
+        );
+    }
+    else
+    {
+        throw Exception("Unknown model type: " + type, ErrorCodes::INVALID_CONFIG_PARAMETER);
+    }
+}
+
+}

dbms/src/Interpreters/ExternalModels.h

@@ -0,0 +1,41 @@
+#pragma once
+
+#include <Dictionaries/CatBoostModel.h>
+#include <Interpreters/ExternalLoader.h>
+#include <common/logger_useful.h>
+#include <memory>
+
+
+namespace DB
+{
+
+class Context;
+
+/// Manages user-defined models.
+class ExternalModels : public ExternalLoader
+{
+public:
+    using ModelPtr = std::shared_ptr<IModel>;
+
+    /// Models will be loaded immediately and then will be updated in separate thread, each 'reload_period' seconds.
+    ExternalModels(Context & context, bool throw_on_error);
+
+    /// Forcibly reloads specified model.
+    void reloadModel(const std::string & name) { reload(name); }
+
+    ModelPtr getModel(const std::string & name) const
+    {
+        return std::static_pointer_cast<IModel>(getLoadable(name));
+    }
+
+protected:
+
+    std::unique_ptr<IExternalLoadable> create(const std::string & name, const Configuration & config,
+                                              const std::string & config_prefix) override;
+
+private:
+
+    Context & context;
+};
+
+}

dbms/src/Interpreters/IExternalLoadable.h

@@ -0,0 +1,45 @@
+#pragma once
+#include <string>
+#include <memory>
+#include <Core/Types.h>
+
+
+namespace Poco::Util
+{
+    class AbstractConfiguration;
+}
+
+
+namespace DB
+{
+
+/// Min and max lifetimes for a loadable object or it's entry
+struct ExternalLoadableLifetime final
+{
+    UInt64 min_sec;
+    UInt64 max_sec;
+
+    ExternalLoadableLifetime(const Poco::Util::AbstractConfiguration & config, const std::string & config_prefix);
+};
+
+
+/// Basic interface for external loadable objects. Is used in ExternalLoader.
+class IExternalLoadable : public std::enable_shared_from_this<IExternalLoadable>
+{
+public:
+    virtual ~IExternalLoadable() = default;
+
+    virtual const ExternalLoadableLifetime & getLifetime() const = 0;
+
+    virtual std::string getName() const = 0;
+    /// True if object can be updated when lifetime exceeded.
+    virtual bool supportUpdates() const = 0;
+    /// If lifetime exceeded and isModified() ExternalLoader replace current object with the result of clone().
+    virtual bool isModified() const = 0;
+    /// Returns new object with the same configuration. Is used to update modified object when lifetime exceeded.
+    virtual std::unique_ptr<IExternalLoadable> clone() const = 0;
+
+    virtual std::exception_ptr getCreationException() const = 0;
+};
+
+}

dbms/src/Storages/System/StorageSystemDictionaries.cpp

@@ -76,16 +76,17 @@ BlockInputStreams StorageSystemDictionaries::read(
     ColumnWithTypeAndName col_source{std::make_shared<ColumnString>(), std::make_shared<DataTypeString>(), "source"};
 
     const auto & external_dictionaries = context.getExternalDictionaries();
-    const std::lock_guard<std::mutex> lock{external_dictionaries.dictionaries_mutex};
+    auto objects_map = external_dictionaries.getObjectsMap();
+    const auto & dictionaries = objects_map.get();
 
-    for (const auto & dict_info : external_dictionaries.dictionaries)
+    for (const auto & dict_info : dictionaries)
     {
         col_name.column->insert(dict_info.first);
         col_origin.column->insert(dict_info.second.origin);
 
-        if (dict_info.second.dict)
+        if (dict_info.second.loadable)
         {
-            const auto dict_ptr = dict_info.second.dict->get();
+            const auto dict_ptr = std::static_pointer_cast<IDictionaryBase>(dict_info.second.loadable);
 
             col_type.column->insert(dict_ptr->getTypeName());
 

dbms/tests/external_models/catboost/data/build_catboost.sh

@@ -0,0 +1,17 @@
+#!/usr/bin/env bash
+
+DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
+
+cd $DIR
+git clone https://github.com/catboost/catboost.git
+
+
+cd "${DIR}/catboost/catboost/libs/model_interface"
+../../../ya make -r  -o "${DIR}/build/lib" -j4
+cd $DIR
+ln -sf "${DIR}/build/lib/catboost/libs/model_interface/libcatboostmodel.so" libcatboostmodel.so
+
+cd "${DIR}/catboost/catboost/python-package/catboost"
+../../../ya make -r -DUSE_ARCADIA_PYTHON=no -DPYTHON_CONFIG=python2-config -j4
+cd $DIR
+ln -sf "${DIR}/catboost/catboost/python-package" python-package

dbms/tests/external_models/catboost/helpers/client.py

@@ -0,0 +1,42 @@
+import subprocess
+import threading
+import os
+
+
+class ClickHouseClient:
+    def __init__(self, binary_path, port):
+        self.binary_path = binary_path
+        self.port = port
+
+    def query(self, query, timeout=10, pipe=None):
+
+        result = []
+        process = []
+
+        def run(path, port, text, result, in_pipe, process):
+
+            if in_pipe is None:
+                in_pipe = subprocess.PIPE
+
+            pipe = subprocess.Popen([path, 'client', '--port', str(port), '-q', text],
+                                    stdin=in_pipe, stdout=subprocess.PIPE, stderr=subprocess.PIPE, close_fds=True)
+            process.append(pipe)
+            stdout_data, stderr_data = pipe.communicate()
+
+            if stderr_data:
+                raise Exception('Error while executing query: {}\nstdout:\n{}\nstderr:\n{}'
+                                .format(text, stdout_data, stderr_data))
+
+            result.append(stdout_data)
+
+        thread = threading.Thread(target=run, args=(self.binary_path, self.port, query, result, pipe, process))
+        thread.start()
+        thread.join(timeout)
+        if thread.isAlive():
+            if len(process):
+                process[0].kill()
+            thread.join()
+            raise Exception('timeout exceed for query: ' + query)
+
+        if len(result):
+            return result[0]

dbms/tests/external_models/catboost/helpers/generate.py

@@ -0,0 +1,15 @@
+import numpy as np
+
+
+def generate_uniform_int_column(size, low, high, seed=0):
+    np.random.seed(seed)
+    return np.random.randint(low, high, size)
+
+
+def generate_uniform_float_column(size, low, high, seed=0):
+    np.random.seed(seed)
+    return np.random.random(size) * (high - low) + low
+
+
+def generate_uniform_string_column(size, samples, seed):
+    return np.array(samples)[generate_uniform_int_column(size, 0, len(samples), seed)]

dbms/tests/external_models/catboost/helpers/server.py

@@ -0,0 +1,67 @@
+import subprocess
+import threading
+import socket
+import time
+
+
+class ClickHouseServer:
+    def __init__(self, binary_path, config_path, stdout_file=None, stderr_file=None, shutdown_timeout=10):
+        self.binary_path = binary_path
+        self.config_path = config_path
+        self.pipe = None
+        self.stdout_file = stdout_file
+        self.stderr_file = stderr_file
+        self.shutdown_timeout = shutdown_timeout
+
+    def start(self):
+        cmd = [self.binary_path, 'server', '--config', self.config_path]
+        out_pipe = None
+        err_pipe = None
+        if self.stdout_file is not None:
+            out_pipe = open(self.stdout_file, 'w')
+        if self.stderr_file is not None:
+            err_pipe = open(self.stderr_file, 'w')
+        self.pipe = subprocess.Popen(cmd, stdout=out_pipe, stderr=err_pipe)
+
+    def wait_for_request(self, port, timeout=1):
+        try:
+            s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+            # is not working
+            # s.settimeout(timeout)
+
+            step = 0.01
+            for iter in range(int(timeout / step)):
+                if s.connect_ex(('127.0.0.1', port)) == 0:
+                    return
+                time.sleep(step)
+
+            s.connect(('127.0.0.1', port))
+        except socket.error as socketerror:
+            print "Error: ", socketerror
+            raise
+
+    def shutdown(self, timeout=10):
+
+        def wait(pipe):
+            pipe.wait()
+
+        if self.pipe is not None:
+            self.pipe.terminate()
+            thread = threading.Thread(target=wait, args=(self.pipe,))
+            thread.start()
+            thread.join(timeout)
+            if thread.isAlive():
+                self.pipe.kill()
+                thread.join()
+
+            if self.pipe.stdout is not None:
+                self.pipe.stdout.close()
+            if self.pipe.stderr is not None:
+                self.pipe.stderr.close()
+
+    def __enter__(self):
+        self.start()
+        return self
+
+    def __exit__(self, type, value, traceback):
+        self.shutdown(self.shutdown_timeout)

dbms/tests/external_models/catboost/helpers/server_with_models.py

@@ -0,0 +1,166 @@
+from server import ClickHouseServer
+from client import ClickHouseClient
+from table import ClickHouseTable
+import os
+import errno
+from shutil import rmtree
+
+SCRIPT_DIR = os.path.dirname(os.path.realpath(__file__))
+CATBOOST_ROOT = os.path.dirname(SCRIPT_DIR)
+
+CLICKHOUSE_CONFIG = \
+'''
+<yandex>
+    <timezone>Europe/Moscow</timezone>
+    <listen_host>::</listen_host>
+    <path>{path}</path>
+    <tmp_path>{tmp_path}</tmp_path>
+    <models_config>{models_config}</models_config>
+    <mark_cache_size>5368709120</mark_cache_size>
+    <users_config>users.xml</users_config>
+    <tcp_port>{tcp_port}</tcp_port>
+    <catboost_dynamic_library_path>{catboost_dynamic_library_path}</catboost_dynamic_library_path>
+</yandex>
+'''
+
+CLICKHOUSE_USERS = \
+'''
+<yandex>
+    <profiles>
+        <default>
+        </default>
+	<readonly>
+            <readonly>1</readonly>
+        </readonly>
+    </profiles>
+
+    <users>
+        <readonly>
+            <password></password>
+            <profile>readonly</profile>
+            <quota>default</quota>
+        </readonly>
+
+        <default>
+            <password></password>
+            <profile>default</profile>
+            <quota>default</quota>
+            <networks incl="networks" replace="replace">
+                <ip>::1</ip>
+                <ip>127.0.0.1</ip>
+            </networks>
+
+        </default>
+    </users>
+
+    <quotas>
+        <default>
+        </default>
+    </quotas>
+</yandex>
+'''
+
+CATBOOST_MODEL_CONFIG = \
+'''
+<models>
+    <model>
+        <type>catboost</type>
+        <name>{name}</name>
+        <path>{path}</path>
+        <float_features_count>{float_features_count}</float_features_count>
+        <cat_features_count>{cat_features_count}</cat_features_count>
+        <lifetime>0</lifetime>
+    </model>
+</models>
+'''
+
+
+class ClickHouseServerWithCatboostModels:
+    def __init__(self, name, binary_path, port, shutdown_timeout=10, clean_folder=False):
+        self.models = {}
+        self.name = name
+        self.binary_path = binary_path
+        self.port = port
+        self.shutdown_timeout = shutdown_timeout
+        self.clean_folder = clean_folder
+        self.root = os.path.join(CATBOOST_ROOT, 'data', 'servers')
+        self.config_path = os.path.join(self.root, 'config.xml')
+        self.users_path = os.path.join(self.root, 'users.xml')
+        self.models_dir = os.path.join(self.root, 'models')
+        self.server = None
+
+    def _get_server(self):
+        stdout_file = os.path.join(self.root, 'server_stdout.txt')
+        stderr_file = os.path.join(self.root, 'server_stderr.txt')
+        return ClickHouseServer(self.binary_path, self.config_path, stdout_file, stderr_file, self.shutdown_timeout)
+
+    def add_model(self, model_name, model, float_features_count, cat_features_count):
+        self.models[model_name] = (float_features_count, cat_features_count, model)
+
+    def apply_model(self, name, df, cat_feature_names):
+        names = list(df)
+        float_feature_names = tuple(name for name in names if name not in cat_feature_names)
+        with ClickHouseTable(self.server, self.port, name, df) as table:
+            return table.apply_model(name, cat_feature_names, float_feature_names)
+
+    def _create_root(self):
+        try:
+            os.makedirs(self.root)
+        except OSError as exc:  # Python >2.5
+            if exc.errno == errno.EEXIST and os.path.isdir(self.root):
+                pass
+            else:
+                raise
+
+    def _clean_root(self):
+        rmtree(self.root)
+
+    def _save_config(self):
+        params = {
+            'tcp_port': self.port,
+            'path': os.path.join(self.root, 'clickhouse'),
+            'tmp_path': os.path.join(self.root, 'clickhouse', 'tmp'),
+            'models_config': os.path.join(self.models_dir, '*_model.xml'),
+            'catboost_dynamic_library_path': os.path.join(CATBOOST_ROOT, 'data', 'libcatboostmodel.so')
+        }
+        config = CLICKHOUSE_CONFIG.format(**params)
+
+        with open(self.config_path, 'w') as f:
+            f.write(config)
+
+        with open(self.users_path, 'w') as f:
+            f.write(CLICKHOUSE_USERS)
+
+    def _save_models(self):
+        if not os.path.exists(self.models_dir):
+            os.makedirs(self.models_dir)
+
+        for name, params in self.models.items():
+            float_features_count, cat_features_count, model = params
+            model_path = os.path.join(self.models_dir, name + '.cbm')
+            config_path = os.path.join(self.models_dir, name + '_model.xml')
+            params = {
+                'name': name,
+                'path': model_path,
+                'float_features_count': float_features_count,
+                'cat_features_count': cat_features_count
+            }
+            config = CATBOOST_MODEL_CONFIG.format(**params)
+            with open(config_path, 'w') as f:
+                f.write(config)
+
+            model.save_model(model_path)
+
+    def __enter__(self):
+        self._create_root()
+        self._save_config()
+        self._save_models()
+        self.server = self._get_server().__enter__()
+        return self
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        res = self.server.__exit__(exc_type, exc_val, exc_tb)
+        if self.clean_folder:
+            self._clean_root()
+        return res
+

dbms/tests/external_models/catboost/helpers/table.py

@@ -0,0 +1,69 @@
+from server import ClickHouseServer
+from client import ClickHouseClient
+from pandas import DataFrame
+import os
+import threading
+import tempfile
+
+
+class ClickHouseTable:
+    def __init__(self, server, port, table_name, df):
+        self.server = server
+        self.port = port
+        self.table_name = table_name
+        self.df = df
+
+        if not isinstance(self.server, ClickHouseServer):
+            raise Exception('Expected ClickHouseServer, got ' + repr(self.server))
+        if not isinstance(self.df, DataFrame):
+            raise Exception('Expected DataFrame, got ' + repr(self.df))
+
+        self.server.wait_for_request(port)
+        self.client = ClickHouseClient(server.binary_path, port)
+
+    def _convert(self, name):
+        types_map = {
+            'float64': 'Float64',
+            'int64': 'Int64',
+            'float32': 'Float32',
+            'int32': 'Int32'
+        }
+
+        if name in types_map:
+            return types_map[name]
+        return 'String'
+
+    def _create_table_from_df(self):
+        self.client.query('create database if not exists test')
+        self.client.query('drop table if exists test.{}'.format(self.table_name))
+
+        column_types = list(self.df.dtypes)
+        column_names = list(self.df)
+        schema = ', '.join((name + ' ' + self._convert(str(t)) for name, t in zip(column_names, column_types)))
+        print 'schema:', schema
+
+        create_query = 'create table test.{} (date Date DEFAULT today(), {}) engine = MergeTree(date, (date), 8192)'
+        self.client.query(create_query.format(self.table_name, schema))
+
+        insert_query = 'insert into test.{} ({}) format CSV'
+
+        with tempfile.TemporaryFile() as tmp_file:
+            self.df.to_csv(tmp_file, header=False, index=False)
+            tmp_file.seek(0)
+            self.client.query(insert_query.format(self.table_name, ', '.join(column_names)), pipe=tmp_file)
+
+    def apply_model(self, model_name, float_columns, cat_columns):
+        columns = ', '.join(list(float_columns) + list(cat_columns))
+        query = "select modelEvaluate('{}', {}) from test.{} format TSV"
+        result = self.client.query(query.format(model_name, columns, self.table_name))
+        return tuple(map(float, filter(len, map(str.strip, result.split()))))
+
+    def _drop_table(self):
+        self.client.query('drop table test.{}'.format(self.table_name))
+
+    def __enter__(self):
+        self._create_table_from_df()
+        return self
+
+    def __exit__(self, type, value, traceback):
+        self._drop_table()

dbms/tests/external_models/catboost/helpers/train.py

@@ -0,0 +1,28 @@
+import os
+import sys
+from pandas import DataFrame
+
+SCRIPT_DIR = os.path.dirname(os.path.realpath(__file__))
+CATBOOST_ROOT = os.path.dirname(SCRIPT_DIR)
+CATBOOST_PYTHON_DIR = os.path.join(CATBOOST_ROOT, 'data', 'python-package')
+
+if CATBOOST_PYTHON_DIR not in sys.path:
+    sys.path.append(CATBOOST_PYTHON_DIR)
+
+
+import catboost
+from catboost import CatBoostClassifier
+
+
+def train_catboost_model(df, target, cat_features, params, verbose=True):
+
+    if not isinstance(df, DataFrame):
+        raise Exception('DataFrame object expected, but got ' + repr(df))
+
+    print 'features:', df.columns.tolist()
+
+    cat_features_index = list(df.columns.get_loc(feature) for feature in cat_features)
+    print 'cat features:', cat_features_index
+    model = CatBoostClassifier(**params)
+    model.fit(df, target, cat_features=cat_features_index, verbose=verbose)
+    return model

dbms/tests/external_models/catboost/pytest.ini

@@ -0,0 +1,3 @@
+[pytest]
+python_files = test.py
+norecursedirs=data

dbms/tests/external_models/catboost/test_apply_catboost_model/test.py

@@ -0,0 +1,236 @@
+from helpers.server_with_models import ClickHouseServerWithCatboostModels
+from helpers.generate import generate_uniform_string_column, generate_uniform_float_column, generate_uniform_int_column
+from helpers.train import train_catboost_model
+import os
+import numpy as np
+from pandas import DataFrame
+
+
+PORT = int(os.environ.get('CLICKHOUSE_TESTS_PORT', '9000'))
+CLICKHOUSE_TESTS_SERVER_BIN_PATH = os.environ.get('CLICKHOUSE_TESTS_SERVER_BIN_PATH', '/usr/bin/clickhouse')
+
+
+def add_noise_to_target(target, seed, threshold=0.05):
+    col = generate_uniform_float_column(len(target), 0., 1., seed + 1) < threshold
+    return target * (1 - col) + (1 - target) * col
+
+
+def check_predictions(test_name, target, pred_python, pred_ch, acc_threshold):
+    ch_class = pred_ch.astype(int)
+    python_class = pred_python.astype(int)
+    if not np.array_equal(ch_class, python_class):
+        raise Exception('Got different results:\npython:\n' + str(python_class) + '\nClickHouse:\n' + str(ch_class))
+
+    acc = 1 - np.sum(np.abs(ch_class - np.array(target))) / (len(target) + .0)
+    assert acc >= acc_threshold
+    print test_name, 'accuracy: {:.10f}'.format(acc)
+
+
+def test_apply_float_features_only():
+
+    name = 'test_apply_float_features_only'
+
+    train_size = 10000
+    test_size = 10000
+
+    def gen_data(size, seed):
+        data = {
+            'a': generate_uniform_float_column(size, 0., 1., seed + 1),
+            'b': generate_uniform_float_column(size, 0., 1., seed + 2),
+            'c': generate_uniform_float_column(size, 0., 1., seed + 3)
+        }
+        return DataFrame.from_dict(data)
+
+    def get_target(df):
+        def target_filter(row):
+            return 1 if (row['a'] > .3 and row['b'] > .3) or (row['c'] < .4 and row['a'] * row['b'] > 0.1) else 0
+        return df.apply(target_filter, axis=1).as_matrix()
+
+    train_df = gen_data(train_size, 42)
+    test_df = gen_data(test_size, 43)
+
+    train_target = get_target(train_df)
+    test_target = get_target(test_df)
+
+    print
+    print 'train target', train_target
+    print 'test target', test_target
+
+    params = {
+        'iterations': 4,
+        'depth': 2,
+        'learning_rate': 1,
+        'loss_function': 'Logloss'
+    }
+
+    model = train_catboost_model(train_df, train_target, [], params)
+    pred_python = model.predict(test_df)
+
+    server = ClickHouseServerWithCatboostModels(name, CLICKHOUSE_TESTS_SERVER_BIN_PATH, PORT)
+    server.add_model(name, model, 3, 0)
+    with server:
+        pred_ch = (np.array(server.apply_model(name, test_df, [])) > 0).astype(int)
+
+    print 'python predictions', pred_python
+    print 'clickhouse predictions', pred_ch
+
+    check_predictions(name, test_target, pred_python, pred_ch, 0.9)
+
+
+def test_apply_float_features_with_string_cat_features():
+
+    name = 'test_apply_float_features_with_string_cat_features'
+
+    train_size = 10000
+    test_size = 10000
+
+    def gen_data(size, seed):
+        data = {
+            'a': generate_uniform_float_column(size, 0., 1., seed + 1),
+            'b': generate_uniform_float_column(size, 0., 1., seed + 2),
+            'c': generate_uniform_string_column(size, ['a', 'b', 'c'], seed + 3),
+            'd': generate_uniform_string_column(size, ['e', 'f', 'g'], seed + 4)
+        }
+        return DataFrame.from_dict(data)
+
+    def get_target(df):
+        def target_filter(row):
+            return 1 if (row['a'] > .3 and row['b'] > .3 and row['c'] != 'a') \
+                        or (row['a'] * row['b'] > 0.1 and row['c'] != 'b' and row['d'] != 'e') else 0
+        return df.apply(target_filter, axis=1).as_matrix()
+
+    train_df = gen_data(train_size, 42)
+    test_df = gen_data(test_size, 43)
+
+    train_target = get_target(train_df)
+    test_target = get_target(test_df)
+
+    print
+    print 'train target', train_target
+    print 'test target', test_target
+
+    params = {
+        'iterations': 6,
+        'depth': 2,
+        'learning_rate': 1,
+        'loss_function': 'Logloss'
+    }
+
+    model = train_catboost_model(train_df, train_target, ['c', 'd'], params)
+    pred_python = model.predict(test_df)
+
+    server = ClickHouseServerWithCatboostModels(name, CLICKHOUSE_TESTS_SERVER_BIN_PATH, PORT)
+    server.add_model(name, model, 2, 2)
+    with server:
+        pred_ch = (np.array(server.apply_model(name, test_df, [])) > 0).astype(int)
+
+    print 'python predictions', pred_python
+    print 'clickhouse predictions', pred_ch
+
+    check_predictions(name, test_target, pred_python, pred_ch, 0.9)
+
+
+def test_apply_float_features_with_int_cat_features():
+
+    name = 'test_apply_float_features_with_int_cat_features'
+
+    train_size = 10000
+    test_size = 10000
+
+    def gen_data(size, seed):
+        data = {
+            'a': generate_uniform_float_column(size, 0., 1., seed + 1),
+            'b': generate_uniform_float_column(size, 0., 1., seed + 2),
+            'c': generate_uniform_int_column(size, 1, 4, seed + 3),
+            'd': generate_uniform_int_column(size, 1, 4, seed + 4)
+        }
+        return DataFrame.from_dict(data)
+
+    def get_target(df):
+        def target_filter(row):
+            return 1 if (row['a'] > .3 and row['b'] > .3 and row['c'] != 1) \
+                        or (row['a'] * row['b'] > 0.1 and row['c'] != 2 and row['d'] != 3) else 0
+        return df.apply(target_filter, axis=1).as_matrix()
+
+    train_df = gen_data(train_size, 42)
+    test_df = gen_data(test_size, 43)
+
+    train_target = get_target(train_df)
+    test_target = get_target(test_df)
+
+    print
+    print 'train target', train_target
+    print 'test target', test_target
+
+    params = {
+        'iterations': 6,
+        'depth': 4,
+        'learning_rate': 1,
+        'loss_function': 'Logloss'
+    }
+
+    model = train_catboost_model(train_df, train_target, ['c', 'd'], params)
+    pred_python = model.predict(test_df)
+
+    server = ClickHouseServerWithCatboostModels(name, CLICKHOUSE_TESTS_SERVER_BIN_PATH, PORT)
+    server.add_model(name, model, 2, 2)
+    with server:
+        pred_ch = (np.array(server.apply_model(name, test_df, [])) > 0).astype(int)
+
+    print 'python predictions', pred_python
+    print 'clickhouse predictions', pred_ch
+
+    check_predictions(name, test_target, pred_python, pred_ch, 0.9)
+
+
+def test_apply_float_features_with_mixed_cat_features():
+
+    name = 'test_apply_float_features_with_mixed_cat_features'
+
+    train_size = 10000
+    test_size = 10000
+
+    def gen_data(size, seed):
+        data = {
+            'a': generate_uniform_float_column(size, 0., 1., seed + 1),
+            'b': generate_uniform_float_column(size, 0., 1., seed + 2),
+            'c': generate_uniform_string_column(size, ['a', 'b', 'c'], seed + 3),
+            'd': generate_uniform_int_column(size, 1, 4, seed + 4)
+        }
+        return DataFrame.from_dict(data)
+
+    def get_target(df):
+        def target_filter(row):
+            return 1 if (row['a'] > .3 and row['b'] > .3 and row['c'] != 'a') \
+                        or (row['a'] * row['b'] > 0.1 and row['c'] != 'b' and row['d'] != 2) else 0
+        return df.apply(target_filter, axis=1).as_matrix()
+
+    train_df = gen_data(train_size, 42)
+    test_df = gen_data(test_size, 43)
+
+    train_target = get_target(train_df)
+    test_target = get_target(test_df)
+
+    print
+    print 'train target', train_target
+    print 'test target', test_target
+
+    params = {
+        'iterations': 6,
+        'depth': 4,
+        'learning_rate': 1,
+        'loss_function': 'Logloss'
+    }
+
+    model = train_catboost_model(train_df, train_target, ['c', 'd'], params)
+    pred_python = model.predict(test_df)
+
+    server = ClickHouseServerWithCatboostModels(name, CLICKHOUSE_TESTS_SERVER_BIN_PATH, PORT)
+    server.add_model(name, model, 2, 2)
+    with server:
+        pred_ch = (np.array(server.apply_model(name, test_df, [])) > 0).astype(int)
+
+    print 'python predictions', pred_python
+    print 'clickhouse predictions', pred_ch
+
+    check_predictions(name, test_target, pred_python, pred_ch, 0.9)