Use rapidjson when AVX2 instructions are not available.

.gitmodules

@@ -82,3 +82,6 @@
 [submodule "contrib/simdjson"]
 	path = contrib/simdjson
 	url = https://github.com/lemire/simdjson.git
+[submodule "contrib/rapidjson"]
+	path = contrib/rapidjson
+	url = https://github.com/Tencent/rapidjson

CMakeLists.txt

@@ -328,6 +328,7 @@ include (cmake/find_base64.cmake)
 include (cmake/find_hyperscan.cmake)
 include (cmake/find_lfalloc.cmake)
 include (cmake/find_simdjson.cmake)
+include (cmake/find_rapidjson.cmake)
 find_contrib_lib(cityhash)
 find_contrib_lib(farmhash)
 find_contrib_lib(metrohash)

cmake/find_rapidjson.cmake

@@ -0,0 +1,9 @@
+if (NOT EXISTS "${ClickHouse_SOURCE_DIR}/contrib/rapidjson/include/rapidjson/rapidjson.h")
+    message (WARNING "submodule contrib/rapidjson is missing. to fix try run: \n git submodule update --init --recursive")
+    return()
+endif ()
+
+option (USE_RAPIDJSON "Use rapidjson" ON)
+set (RAPIDJSON_INCLUDE_DIR "${ClickHouse_SOURCE_DIR}/contrib/rapidjson/include")
+
+message(STATUS "Using rapidjson=${USE_RAPIDJSON}: ${RAPIDJSON_INCLUDE_DIR}")

contrib/rapidjson

@@ -0,0 +1 @@
+Subproject commit 01950eb7acec78818d68b762efc869bba2420d82

dbms/src/Common/config.h.in

@@ -26,6 +26,7 @@
 #cmakedefine01 USE_SSL
 #cmakedefine01 USE_HYPERSCAN
 #cmakedefine01 USE_SIMDJSON
+#cmakedefine01 USE_RAPIDJSON
 #cmakedefine01 USE_LFALLOC
 #cmakedefine01 USE_LFALLOC_RANDOM_HINT
 

dbms/src/Functions/CMakeLists.txt

@@ -73,3 +73,7 @@ endif()
 if(USE_SIMDJSON)
     target_link_libraries(clickhouse_functions PRIVATE ${SIMDJSON_LIBRARY})
 endif()
+
+if(USE_RAPIDJSON)
+    target_include_directories(clickhouse_functions SYSTEM PRIVATE ${RAPIDJSON_INCLUDE_DIR})
+endif()

dbms/src/Functions/FunctionsJSON.cpp

@@ -1,6 +1,7 @@
 #include <Functions/FunctionsJSON.h>
 #include <Functions/DummyJSONParser.h>
 #include <Functions/SimdJSONParser.h>
+#include <Functions/RapidJSONParser.h>
 #include <Common/CpuId.h>
 
 
@@ -16,7 +17,12 @@ void registerFunctionsJSON(FunctionFactory & factory)
         return;
     }
 #endif
+
+#if USE_RAPIDJSON
+    registerFunctionsJSONTemplate<RapidJSONParser>(factory);
+#else
     registerFunctionsJSONTemplate<DummyJSONParser>(factory);
+#endif
 }
 
 }

dbms/src/Functions/RapidJSONParser.h

@@ -0,0 +1,206 @@
+#pragma once
+
+#include <Common/config.h>
+#if USE_RAPIDJSON
+
+#include <common/StringRef.h>
+#include <Common/Exception.h>
+#include <Core/Types.h>
+
+#include <rapidjson/document.h>
+
+
+namespace DB
+{
+
+/// This class can be used as an argument for the template class FunctionJSON.
+/// It provides ability to parse JSONs using rapidjson library.
+struct RapidJSONParser
+{
+    static constexpr bool need_preallocate = false;
+    void preallocate(size_t) {}
+
+    bool parse(const char * data, size_t size)
+    {
+        InputStream in(data, size);
+        document.ParseStream(in);
+        return !document.HasParseError();
+    }
+
+    struct Iterator
+    {
+    public:
+        Iterator() {}
+        Iterator(const rapidjson::Document & document) : value(&document) {}
+        Iterator(const Iterator & src)
+            : value(src.value)
+            , parent_scope_is_object(src.parent_scope_is_object)
+            , current_in_array(src.current_in_array)
+            , end_of_array(src.end_of_array) {}
+
+        Iterator & operator =(const Iterator & src)
+        {
+            value = src.value;
+            parent_scope_is_object = src.parent_scope_is_object;
+            current_in_array = src.current_in_array;
+            end_of_array = src.end_of_array;
+            return *this;
+        }
+
+        const rapidjson::Value & getValue() const { return *value; }
+
+        bool downToArray()
+        {
+            if (value->Empty())
+                return false;
+            current_in_array = &*value->Begin();
+            end_of_array = &*value->End();
+            value = current_in_array;
+            ++current_in_array;
+            parent_scope_is_object = false;
+            return true;
+        }
+
+        bool next()
+        {
+            if (current_in_array == end_of_array)
+                return false;
+            value = current_in_array;
+            ++current_in_array;
+            return true;
+        }
+
+        bool downToObject()
+        {
+            if (value->ObjectEmpty())
+                return false;
+            current_in_object = &*value->MemberBegin();
+            end_of_object = &*value->MemberEnd();
+            value = &current_in_object->value;
+            ++current_in_object;
+            parent_scope_is_object = true;
+            return true;
+        }
+
+        bool downToObject(StringRef & first_key)
+        {
+            if (value->ObjectEmpty())
+                return false;
+            current_in_object = &*value->MemberBegin();
+            end_of_object = &*value->MemberEnd();
+            const auto & name = current_in_object->name;
+            first_key.data = name.GetString();
+            first_key.size = name.GetStringLength();
+            value = &current_in_object->value;
+            ++current_in_object;
+            parent_scope_is_object = true;
+            return true;
+        }
+
+        bool nextKeyValue()
+        {
+            if (current_in_object == end_of_object)
+                return false;
+            value = &current_in_object->value;
+            ++current_in_object;
+            return true;
+        }
+
+        bool nextKeyValue(StringRef & key)
+        {
+            if (current_in_object == end_of_object)
+                return false;
+            const auto & name = current_in_object->name;
+            key.data = name.GetString();
+            key.size = name.GetStringLength();
+            value = &current_in_object->value;
+            ++current_in_object;
+            return true;
+        }
+
+        StringRef getKey() const
+        {
+            const auto & name = (current_in_object - 1)->name;
+            return {name.GetString(), name.GetStringLength()};
+        }
+
+        bool parentScopeIsObject() const { return parent_scope_is_object; }
+
+        bool isInteger() const { return value->IsInt64(); }
+        bool isFloat() const { return value->IsDouble(); }
+        bool isBool() const { return value->IsBool(); }
+        bool isString() const { return value->IsString(); }
+        bool isArray() const { return value->IsArray(); }
+        bool isObject() const { return value->IsObject(); }
+        bool isNull() const { return value->IsNull(); }
+
+        Int64 getInteger() const { return value->GetInt64(); }
+        double getFloat() const { return value->GetDouble(); }
+        bool getBool() const { return value->GetBool(); }
+        StringRef getString() const { return {value->GetString(), value->GetStringLength()}; }
+
+    private:
+        const rapidjson::Value * value = nullptr;
+        bool parent_scope_is_object = false;
+
+        union
+        {
+            const rapidjson::GenericMember<rapidjson::UTF8<>, rapidjson::MemoryPoolAllocator<>> * current_in_object;
+            const rapidjson::Value * current_in_array;
+        };
+        union
+        {
+            const rapidjson::GenericMember<rapidjson::UTF8<>, rapidjson::MemoryPoolAllocator<>> * end_of_object;
+            const rapidjson::Value * end_of_array;
+        };
+    };
+
+    Iterator getRoot() { return Iterator{document}; }
+
+    static bool downToArray(Iterator & it) { return it.downToArray(); }
+    static bool downToObject(Iterator & it) { return it.downToObject(); }
+    static bool downToObject(Iterator & it, StringRef & first_key) { return it.downToObject(first_key); }
+    static bool parentScopeIsObject(const Iterator & it) { return it.parentScopeIsObject(); }
+    static bool next(Iterator & it) { return it.next(); }
+    static bool nextKeyValue(Iterator & it) { return it.nextKeyValue(); }
+    static bool nextKeyValue(Iterator & it, StringRef & key) { return it.nextKeyValue(key); }
+    static bool isInteger(const Iterator & it) { return it.isInteger(); }
+    static bool isFloat(const Iterator & it) { return it.isFloat(); }
+    static bool isString(const Iterator & it) { return it.isString(); }
+    static bool isArray(const Iterator & it) { return it.isArray(); }
+    static bool isObject(const Iterator & it) { return it.isObject(); }
+    static bool isBool(const Iterator & it) { return it.isBool(); }
+    static bool isNull(const Iterator & it) { return it.isNull(); }
+    static StringRef getKey(const Iterator & it) { return it.getKey(); }
+    static StringRef getString(const Iterator & it) { return it.getString(); }
+    static Int64 getInteger(const Iterator & it) { return it.getInteger(); }
+    static double getFloat(const Iterator & it) { return it.getFloat(); }
+    static bool getBool(const Iterator & it) { return it.getBool(); }
+
+private:
+    class InputStream
+    {
+    public:
+        InputStream(const char * data, size_t size) : begin(data), end(data + size), current(data) {}
+
+        using Ch = char;
+        Ch Peek() { if (current == end) return 0; return *current; }
+        Ch Take() { if (current == end) return 0; return *current++; }
+        size_t Tell() const { return current - begin; }
+
+        Ch* PutBegin() { return nullptr; }
+        void Put(Ch) {}
+        void Flush() {}
+        size_t PutEnd(Ch*) { return 0; }
+
+    private:
+        const char * begin;
+        const char * end;
+        const char * current;
+    };
+
+    rapidjson::Document document;
+};
+
+}
+#endif