单一的单例有时很难满足需求，我们往往需要根据不同的规格，创建不同类型的单例实例。
本例实现满足上述需求的单例池。
代码目录如下，
图片.png
代码如下，
test/CMakeLists.txt
cmake_minimum_required(VERSION 2.6)
if(APPLE)
message(STATUS "This is Apple, do nothing.")
set(CMAKE_MACOSX_RPATH 1)
set(CMAKE_PREFIX_PATH /Users/aabjfzhu/software/vcpkg/ports/cppwork/vcpkg_installed/x64-osx/share )
elseif(UNIX)
message(STATUS "This is linux, set CMAKE_PREFIX_PATH.")
set(CMAKE_PREFIX_PATH /vcpkg/ports/cppwork/vcpkg_installed/x64-linux/share)
endif(APPLE)
project(multiton)
set(CMAKE_CXX_STANDARD 20)
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-narrowing")
add_definitions(-g)
find_package(ZLIB)
find_package(OpenCV REQUIRED )
find_package(Arrow CONFIG REQUIRED)
find_package(unofficial-brotli REQUIRED)
find_package(unofficial-utf8proc CONFIG REQUIRED)
find_package(Thrift CONFIG REQUIRED)
find_package(glog REQUIRED)
find_package(OpenSSL REQUIRED)
find_package(Boost REQUIRED COMPONENTS
system
filesystem
serialization
program_options
thread
)
find_package(DataFrame REQUIRED)
if(APPLE)
MESSAGE(STATUS "This is APPLE, set INCLUDE_DIRS")
set(INCLUDE_DIRS ${Boost_INCLUDE_DIRS} /usr/local/include /usr/local/iODBC/include /opt/snowflake/snowflakeodbc/include/ ${CMAKE_CURRENT_SOURCE_DIR}/../include/ ${CMAKE_CURRENT_SOURCE_DIR}/../../../include)
elseif(UNIX)
MESSAGE(STATUS "This is linux, set INCLUDE_DIRS")
set(INCLUDE_DIRS ${Boost_INCLUDE_DIRS} /usr/local/include ${CMAKE_CURRENT_SOURCE_DIR}/../include/ ${CMAKE_CURRENT_SOURCE_DIR}/../../../include/)
endif(APPLE)
if(APPLE)
MESSAGE(STATUS "This is APPLE, set LINK_DIRS")
set(LINK_DIRS /usr/local/lib /usr/local/iODBC/lib /opt/snowflake/snowflakeodbc/lib/universal)
elseif(UNIX)
MESSAGE(STATUS "This is linux, set LINK_DIRS")
set(LINK_DIRS ${Boost_INCLUDE_DIRS} /usr/local/lib /vcpkg/ports/cppwork/vcpkg_installed/x64-linux/lib)
endif(APPLE)
if(APPLE)
MESSAGE(STATUS "This is APPLE, set ODBC_LIBS")
set(ODBC_LIBS iodbc iodbcinst)
elseif(UNIX)
MESSAGE(STATUS "This is linux, set LINK_DIRS")
set(ODBC_LIBS odbc odbcinst ltdl)
endif(APPLE)
include_directories(${INCLUDE_DIRS})
LINK_DIRECTORIES(${LINK_DIRS})
file( GLOB test_file_list ${CMAKE_CURRENT_SOURCE_DIR}/*.cpp)
file( GLOB APP_SOURCES ${CMAKE_CURRENT_SOURCE_DIR}/../impl/*.cpp ${CMAKE_CURRENT_SOURCE_DIR}/../include/*.h ${CMAKE_CURRENT_SOURCE_DIR}/../include/*.cpp ${CMAKE_CURRENT_SOURCE_DIR}/../../../include/arr_/impl/*.cpp ${CMAKE_CURRENT_SOURCE_DIR}/../../../include/http/impl/*.cpp ${CMAKE_CURRENT_SOURCE_DIR}/../../../include/yaml/impl/*.cpp ${CMAKE_CURRENT_SOURCE_DIR}/../../../include/df/impl/*.cpp ${CMAKE_CURRENT_SOURCE_DIR}/../../../include/death_handler/impl/*.cpp)
add_library(${PROJECT_NAME}_lib SHARED ${APP_SOURCES} ${test_file})
target_link_libraries(${PROJECT_NAME}_lib ${Boost_LIBRARIES} ZLIB::ZLIB glog::glog DataFrame::DataFrame ${OpenCV_LIBS})
target_link_libraries(${PROJECT_NAME}_lib OpenSSL::SSL OpenSSL::Crypto libgtest.a pystring libyaml-cpp.a libgmock.a ${ODBC_LIBS} libnanodbc.a pthread dl backtrace libzstd.a libbz2.a libsnappy.a re2::re2 parquet lz4 unofficial::brotli::brotlidec-static unofficial::brotli::brotlienc-static unofficial::brotli::brotlicommon-static utf8proc thrift::thrift arrow arrow_dataset)
foreach( test_file ${test_file_list} )
file(RELATIVE_PATH filename ${CMAKE_CURRENT_SOURCE_DIR} ${test_file})
string(REPLACE ".cpp" "" file ${filename})
add_executable(${file} ${test_file})
target_link_libraries(${file} ${PROJECT_NAME}_lib)
endforeach( test_file ${test_file_list})
test/multiton_test.cpp
#include "death_handler/death_handler.h"
#include <glog/logging.h>
#include "multiton.hpp"
#include <utility>
#include <gtest/gtest.h>
#include "df/df.h"
int main(int argc, char** argv) {
FLAGS_log_dir = "./";
FLAGS_alsologtostderr = true;
// 日志级别 INFO, WARNING, ERROR, FATAL 的值分别为0、1、2、3
FLAGS_minloglevel = 0;
Debug::DeathHandler dh;
google::InitGoogleLogging("./logs.log");
testing::InitGoogleTest(&argc, argv);
int ret = RUN_ALL_TESTS();
return ret;
}
GTEST_TEST(MultitonTests, Multiton) {
auto main = MultitonPrinter::get(Importance::Primary);
auto aux = MultitonPrinter::get(Importance::Secondary);
auto aux2 = MultitonPrinter::get(Importance::Secondary);
auto small = MultitonCircle::get(Size::Small);
auto medium = MultitonCircle::get(Size::Medium, 2.0f);
auto large = MultitonCircle::get(Size::Large, 3.0f);
}
include/multiton.hpp
#ifndef _FREDRIC_MULTITON_HPP_
#define _FREDRIC_MULTITON_HPP_
#include <iostream>
#include <memory>
#include <map>
#include <string>
enum class Importance {
Primary,
Secondary,
Tertiary
};
enum class Size {
Large,
Medium,
Small
};
template <typename T, typename Key = std::string>
class Multiton {
public:
template<typename ... Args>
static std::shared_ptr<T> get(Key const& key, Args&& ... args) {
if(auto const it = instances.find(key); it!=instances.end()) {
return it->second;
}
auto instance = std::make_shared<T>(std::forward<Args>(args)...);
instances[key] = instance;
return instance;
}
private:
static std::map<Key, std::shared_ptr<T>> instances;
protected:
Multiton() = default;
virtual ~Multiton() = default;
};
template <typename T, typename Key>
std::map<Key, std::shared_ptr<T>> Multiton<T, Key>::instances{};
class Printer {
static int totalInstanceCount;
public:
Printer() {
++ Printer::totalInstanceCount;
std::cout << "A total of " <<
Printer::totalInstanceCount <<
" instances created so far\n";
}
};
int Printer::totalInstanceCount = 0;
class Circle {
static int totalInstanceCount;
float redius {1.0f};
public:
Circle() {
++ Circle::totalInstanceCount;
std::cout << "A total of " <<
Circle::totalInstanceCount <<
" circles created so far\n";
}
Circle(float redius_): redius {redius_} {
++ Circle::totalInstanceCount;
std::cout << "A total of " <<
Circle::totalInstanceCount <<
" circles created so far\n";
}
};
int Circle::totalInstanceCount = 0;
using MultitonPrinter = Multiton<Printer, Importance>;
using MultitonCircle = Multiton<Circle, Size>;
#endif
程序输出如下，
图片.png
网友评论