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CLion之C++框架篇-优化开源框架，引入curl，实现get方式获取资源（四）

背景

　　结合上一篇CLion之C++框架篇-优化框架，引入boost（三），继续进行框架优化！在项目中，我们经常会通过get方式拉取第三方资源，这一版优化引入类库curl，用来拉取第三方资源库。

　　开源框架代码：https://github.com/rtxbc/cplus/tree/master/work

配置使用

cmake_minimum_required(VERSION 3.11.2)

project(work)

message(STATUS "start load boost ========================================")
# BOOST
## 设置个变量控制
SET(BOOST_MIN_VERSION "1.67.0")
## 动态查找
FIND_PACKAGE(Boost ${BOOST_MIN_VERSION} REQUIRED)
if(NOT Boost_FOUND)
    message(FATAL_ERROR "Fatal error:Boost (version >=${BOOST_MIN_VERSION}) required.
")
endif()
message(STATUS "Boost_INCLUDE_DIRS: ${Boost_INCLUDE_DIRS}")
message(STATUS "Boost_LIBRARIES: ${BOOST_LIBRARY_DIRS}")
message(STATUS "Boost_VERSION: ${Boost_VERSION}")
## 头文件
INCLUDE_DIRECTORIES(${Boost_INCLUDE_DIRS})
LINK_DIRECTORIES(${Boost_LIBRARY_DIRS})
# .BOOST
message(STATUS "end load boost ========================================")


# 编译google test，会在当前目录生成libtest.a静态库
add_subdirectory(lib/ext/googletest)

#头文件
INCLUDE_DIRECTORIES(${PROJECT_SOURCE_DIR}/src/include ${PROJECT_SOURCE_DIR}lib/ext/googletest/include)


#库文件 : libtest.a 添加到链接路径中
link_directories(${PROJECT_SOURCE_DIR}/lib ${PROJECT_SOURCE_DIR}/lib/ext/googletest /usr/local/opt/curl/lib/)

#编译器相关设置
set(CMAKE_RUNTIME_OUTPUT_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}/output/bin")
set(LIBRARIES pthread)
set(CMAKE_CXX_STANDARD 11)
set(CMAKE_CXX_COMPILER      "clang++" )         # 显示指定使用的C++编译器
set(CMAKE_CXX_FLAGS   "-g")                     # 调试信息
set(CMAKE_CXX_FLAGS   "-Wall")                  # 开启所有警告
set(CMAKE_CXX_FLAGS   "-lboost_date_time-mt-d") # boost

#源码目录
FILE(GLOB_RECURSE SOURCEFILES ${PROJECT_SOURCE_DIR}/src/utility/*.cpp)
FILE(GLOB_RECURSE TEST_SOURCEFILES ${PROJECT_SOURCE_DIR}/src/test/*.cpp)

add_custom_target(cmake-build-debug)
add_executable(${PROJECT_NAME} ${PROJECT_SOURCE_DIR}/src/main/main.cpp ${SOURCEFILES})
add_executable(work_test ${TEST_SOURCEFILES} ${SOURCEFILES})

target_link_libraries(${PROJECT_NAME} gtest ${Boost_LIBRARIES} curl)
target_link_libraries(work_test gtest ${Boost_LIBRARIES} curl)

使用

设定头部文件:

//
// Created by Zhou,Baochuan on 18/6/5.
//

#ifndef WORK_HTTP_H
#define WORK_HTTP_H

#include "common.h"
#include <curl/curl.h>

namespace work {
    class Http {
    public:
        Http();
        ~Http();
        static string get(string url, unsigned retries = 3);
    };
}

#endif //WORK_HTTP_H

注意：get方法中增加了retries重试机制。在实现中看一下细节！

//
// Created by Zhou,Baochuan on 18/6/5.
//

#include "http.h"

using namespace work;

Http::Http()
{
    curl_global_init(CURL_GLOBAL_NOTHING);
}

Http::~Http()
{
    curl_global_cleanup();
}

size_t req_reply(void* ptr, size_t size, size_t nmemb, void* stream) {
    //cout << "----->reply" << endl;
    std::string* str = (std::string*)stream;
    //cout << *str << endl;
    (*str).append((char*)ptr, size * nmemb);
    return size * nmemb;
}
string Http::get(string url, unsigned int retries)
{
    string response;
    CURL *curl;
    struct curl_slist *headers = NULL;
    //headers = curl_slist_append(headers, "Accept: Agent-007");

    curl = curl_easy_init() ;
    if (curl) {
        //curl_easy_setopt(curl, CURLOPT_PROXY, "10.99.60.201:8080");// 代理
        curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);
        curl_easy_setopt(curl, CURLOPT_URL, url.c_str());
        curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, req_reply);
        curl_easy_setopt(curl, CURLOPT_WRITEDATA, (void*) &response);
        //curl_easy_setopt(curl, CURLOPT_VERBOSE, 1);
        curl_easy_setopt(curl, CURLOPT_TIMEOUT, 0); // 传输超时
        curl_easy_setopt(curl, CURLOPT_CONNECTTIMEOUT, 0); // 连接超时
        curl_easy_setopt(curl, CURLOPT_NOSIGNAL, 1L);
        curl_easy_setopt(curl, CURLOPT_FORBID_REUSE, 1);
        CURLcode res = curl_easy_perform(curl);   // 执行

        // 重试
        while (res != CURLE_OK && --retries > 0) {
            res = curl_easy_perform(curl);   // 执行
        }

        curl_easy_cleanup(curl);
    }
    curl_slist_free_all(headers);
    return response;
}

测试代码：

#include "common.h"
#include "http.h"
#include <gtest/gtest.h>

using namespace work;

// curl版本要求
TEST(curl, all)
{
    EXPECT_EQ(3, CURLVERSION_NOW);
    Http http;
    string url = "http://47.95.220.249/";
    ASSERT_FALSE(http.get(url).empty());
}

CURL 注意事项

1、解决线程安全及避免core错误问题方式

　　1） curl_global_init（）在多线程环境下，是线程不安全的。所以在多线程环境下，要在主线程中调用这个方法。配套的，在主线程中调用curl_global_cleanup()方法。

　　2）curl_easy_setopt(curl, CURLOPT_NOSIGNAL, 1L); 控制域名解析的超时，其需要一个sigjmp_buf型的全局变量，多线程时会修改它。

　　3) curl_easy_setopt(curl, CURLOPT_FORBID_REUSE, 1);默认情况下libcurl完成一个任务以后，出于重用连接的考虑不会马上关闭。如果没有新的TCP请求来重用这个连接，那么只能等到CLOSE_WAIT超时，这个时间默认在7200秒甚至更高，太多的CLOSE_WAIT连接会导致性能问题

2、要想让curl_easy_perform()，能够执行，必须得有个配套方法curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, req_reply);