从0开始搭建编程框架——主框架和源码

一个良好的结构是“对修改关闭，对扩展开放”的。（转载请指明出于breaksoftware的csdn博客）

这个过程就像搭建积木。框架本身需要有足够的向内扩展能力以使自身有进化能力，其次要有足够的外向扩展能力以使其可以方便定制业务。一般来说，我们让使用者继承框架暴露的接口，或者填充一些配置项以达到“扩展”的目的。

对内部分，我们称为模块（module）。它主要提供initialize方法供各个模块加载配置

template<class T>
class Module {
public:Module() {};virtual ~Module() {};
public:virtual bool initialize() final {config_callback fn = boost::bind(&T::on_init, dynamic_cast<T*>(this), _1);ConfigRegistry::get_mutable_instance().register_config_dir(dynamic_cast<T*>(this)->name(), fn);return true;};
private:virtual void on_init(const char*) = 0;virtual const char* name() = 0;
};

module是个模板类，这是因为第8行我们需要知道子类的类型，以将其on_init方法绑定到一个函数对象fn上。fn最终会和模块的名称通过单例类ConfigRegistry的register_config_dir绑定在一起（9行）。

ConfigRegistry是框架内模块中唯一不继承于Module的单例类。

typedef boost::function<void(const char*)> config_callback;class ConfigRegistry :public boost::serialization::singleton<ConfigRegistry>
{
public:ConfigRegistry(void);~ConfigRegistry(void);
public:bool initialize(const char* conf_path);bool register_config_dir(const char* name,config_callback& f_config_proc) const;
private:void init_from_file(const char* conf_path);
private:peleus::modules::configure::config_registry_conf _config;struct std::map<std::string, std::string> _config_name_path;
};

它在程序一开始时就启动执行，以把框架的整体配置读取进来（9行），然后各个模块初始化时，让它们加载自己对应的配置（38行）

using ::peleus::modules::configure::module_conf;ConfigRegistry::ConfigRegistry(void) {
}ConfigRegistry::~ConfigRegistry(void) {
}bool ConfigRegistry::initialize(const char* conf_path) {bool suc = peleus::utils::file2conf(conf_path, _config);LOG(DEBUG) << "ConfigRegistry::initialize from " << conf_path;if (!suc) {LOG(FATAL) << "ConfigRegistry::initialize Fatal";return suc;}int size = _config.modules_conf_size();for (int i = 0; i < size; i++) {const module_conf& conf = _config.modules_conf(i);_config_name_path[conf.name()] = conf.path();LOG(DEBUG) << "ConfigRegistry::initialize "<< conf.name().c_str() << " " << conf.path().c_str();}LOG(DEBUG) << "ConfigRegistry::initialize Success";return suc;
}bool ConfigRegistry::register_config_dir(const char* name,config_callback& f_config_proc) const
{auto it = _config_name_path.find(std::string(name));if (it == _config_name_path.end()) {LOG(WARNING) << "ConfigRegistry::register_config_dir search " << name << " failed";return false;}LOG(DEBUG) << "ConfigRegistry::register_config_dir search " << name << " path: " << it->second.c_str();f_config_proc(it->second.c_str());return true;
}

第10行执行配置读取和转换。之前做服务开发时，最烦的就是配置解析和请求协议解析。在此要特别感谢google的protobuf，真是个好东西，让我把配置解析的代码也给省了

#include <string>
#include <fstream>
#include <streambuf>
#include <butil/logging.h>
#include <boost/filesystem.hpp>
#include <google/protobuf/text_format.h>namespace peleus {
namespace utils {template <class T>
bool file2conf(const char* path, T& t) {if (!boost::filesystem::exists(path)) {LOG(ERROR) << path << " is not exist";return false;}std::ifstream infile(path);std::string content = std::string(std::istreambuf_iterator<char>(infile),std::istreambuf_iterator<char>());return  google::protobuf::TextFormat::ParseFromString(content, &t);
}}
}

对外的扩展，我们称为插件（plugin）。插件是由若干组件（Component）组成的，其暴露的on_init方法供各个组件子类实现，以加载配置

class Component {
public:explicit Component(const char* name) : _name(std::string(name)) {};virtual ~Component() {};
public:const char* name() const {return _name.c_str();};
public:virtual void on_init(const char* conf_path) = 0;virtual void reset() = 0;
private:Component();
private:std::string _name;
};

组件具有承载业务逻辑的作用。在《从0开始搭建编程框架——思考》一文中，我们设定每个异步过程都是以一个服务形式提供的。于是有些组件将提供服务功能，即它是个入口，这样就需要继承Entrance类

class Entrance : public Component {
public:explicit Entrance(const char* name) : Component(name) {};virtual ~Entrance() {};
public:virtual void on_init(const char*) = 0;virtual void reset() = 0;
};typedef boost::shared_ptr<Entrance> smart_ptr;
typedef smart_ptr (*creator_t)(const char*);

组件需要向框架注册，框架提供下面的方法以支持

//h
bool register_creator(const char*, creator_t);
creator_t lookup_creator(const char*);template<class type> smart_ptr creator(const char* name) {return boost::make_shared<type>(name);
};template<class type> bool register_class(const char* name) {return register_creator(name, creator<type>);
};//cpp
bool register_creator(const char* name, creator_t creator) {return peleus::modules::CreatorRepertory::get_mutable_instance().register_creator(name, creator);
}creator_t lookup_creator(const char* name) {return peleus::modules::CreatorRepertory::get_mutable_instance().lookup_creator(name);
}

creator和register_class方法会在插件代码中编译，register_creator和lookup_creator会在框架中编译，其中它们连接的函数register_creator将在链接时被确定。

CreatorRepertory类继承于Module，它主要用于注册和查询组件类构造指针，这些指针都是在插件注册时向框架注册绑定的

bool CreatorRepertory::register_creator(const char* name, creator_t creator)
{if (_creators.end() != _creators.find(name)) {LOG(TRACE) << name << " have registed";return true;}_creators[name] = creator;return true;
}creator_t CreatorRepertory::lookup_creator(const char* name) {auto it = _creators.find(name);if (_creators.end() == it) {LOG(FATAL) << "can't lookup " << name  << " creator";return NULL;}return it->second;
}

我们再看下插件管理加载PluginLoader。其核心就是load_plugin_and_run方法。插件可以以静态链接库或者动态链接库供框架使用。

typedef bool (*module_init_func_t)(const char*);void PluginLoader::load_plugin_and_run(const char* so_path, int static_flag, const char* fun_name, const char* conf_path) {module_init_func_t init_func = NULL;if (!static_flag) {FALSE_THROW(boost::filesystem::exists(so_path),"%s can't find %s file", name(), so_path);void* handle = dlopen(so_path, RTLD_NOW | RTLD_GLOBAL);if (!handle) {const char* err_reason = dlerror();FALSE_THROW(!err_reason,"%s load %s error.reason : %s", name(), so_path, err_reason);FALSE_THROW(0, "%s load %s error", name(), so_path);}init_func = (module_init_func_t)dlsym(handle, fun_name);}else {init_func = (module_init_func_t)dlsym((void*)RTLD_LOCAL, fun_name);}FALSE_THROW(init_func, "%s get function %s error", name(), fun_name);FALSE_THROW(init_func(conf_path), "%s call plugin %s func %s error", name(), so_path, fun_name)
}

对外Server只提供一个端口，处理业务的组件对象在init_from_file方法中获取，然后再start方法中运行

void Server::init_from_file(const char* conf_path) {try {entrance_conf config;bool suc = peleus::utils::file2conf(conf_path, config);if (!suc) {FALSE_THROW(0, "init_from_file Fatal: %s", conf_path);}smart_ptr ptr = _entrance_repertory.get_entrance(config.name().c_str());Service* service = dynamic_cast<google::protobuf::Service*>(ptr.get());if (!service) {FALSE_THROW(0, "%s get service error", config.name().c_str());}if (_server.AddService(service, brpc::SERVER_DOESNT_OWN_SERVICE) != 0) {FALSE_THROW(0, "%s Add %s server error", name(), config.name().c_str());}}catch (PeleusException& e) {throw;}catch (const std::exception& exp) {throw;}
}void Server::start() {brpc::ServerOptions options;options.idle_timeout_sec = _config.idle_timeout_sec();options.max_concurrency = _config.max_concurrency();options.num_threads = _config.num_threads();options.internal_port = _config.internal_port();try {if (_server.Start(_config.port(), &options) != 0) {FALSE_THROW(0, "%s start server error", name());}_server.RunUntilAskedToQuit();}catch (PeleusException& e) {throw;}catch (const std::exception& exp) {throw;}
}

提供内部服务的InterServer是类似的

void InterServer::add_inter_service() {TraversalCallback traversal_file = [this](const char* path) {this->init_from_file(path);};TraversalFloder traversal;traversal.set_callback(NULL, traversal_file, __FILE__);traversal.init(_config.inter_servers_conf_path().c_str());
}void InterServer::init_from_file(const char* conf_path) {entrance_conf config;bool suc = peleus::utils::file2conf(conf_path, config);if (!suc) {LOG(FATAL) << "init_from_file Fatal: " << conf_path;return;}add_service(config.name());
}void InterServer::add_service(const std::string& entrance_name) {smart_ptr ptr = _entrance_repertory.get_entrance(entrance_name.c_str());Service* service = dynamic_cast<google::protobuf::Service*>(ptr.get());if (!service) {LOG(WARNING) << name() << " get service error";}if (_server.AddService(service, brpc::SERVER_DOESNT_OWN_SERVICE) != 0) {FALSE_THROW(0, "%s Add %s server error", name(), entrance_name.c_str());}
}void InterServer::start() {brpc::ServerOptions options;options.idle_timeout_sec = _config.idle_timeout_sec();options.max_concurrency = _config.max_concurrency();try {if (_server.Start(_config.port(), &options) != 0) {FALSE_THROW(0, "%s start server error", name());}init_channel();//_server.RunUntilAskedToQuit();}catch (PeleusException& e) {throw;}catch (const std::exception& exp) {throw;}
}void InterServer::init_channel() {brpc::ChannelOptions options;const query_inter_server_conf& conf = _config.query_conf();options.connection_type = conf.connection_type();options.connect_timeout_ms = conf.connect_timeout_ms();options.timeout_ms = conf.timeout_ms();options.max_retry = conf.max_retry();std::string server_lower = conf.server();transform(server_lower.begin(), server_lower.end(), server_lower.begin(), ::toupper);std::stringstream ss;ss << _config.port();std::string port = ss.str();std::string server_port = conf.server();server_port += ":";server_port += port;if (_channel.Init(server_port.c_str(), &options) != 0) {FALSE_THROW(0, "%s fail to initialize channel %s", name(), server_port.c_str());}
}

Server和InterServer所使用的组件是具有“入口”性质的，即应该继承于Entrance。与之相关的类EntranceFactory通过create将各个对象构造出来

smart_ptr EntranceFactory::create(const std::string& entrance_name) {smart_ptr sp;try {auto it = _entrances_conf.find(entrance_name);FALSE_THROW(!(it == _entrances_conf.end()), "%s create get %s conf error", name(), entrance_name.c_str());creator_t create_fun = CreatorRepertory::get_mutable_instance().lookup_creator(entrance_name.c_str());FALSE_THROW(create_fun, "%s create lookup %s creator error", name(), entrance_name.c_str());sp = create_fun(entrance_name.c_str());FALSE_THROW(sp.get(), "%s create create %s error", name(), entrance_name.c_str());sp->on_init(it->second.c_str());}   catch (PeleusException& e) {throw;}   catch (const std::exception& exp) {throw;}   return sp;
} 

如此我们便将整个框架搭建出来了。最后看下类图