ROS学习之源码——init() 第一篇

//init.h  文 件
#ifndef ROSCPP_INIT_H
#define ROSCPP_INIT_H

#include "ros/forwards.h"
#include "ros/spinner.h"
#include "common.h"

namespace ros{
    namespace init_options{
        enum InitOption{
        NoSigintHandler = 1 << 0,
        AnonymousName = 1 << 1,
        NoRosout = 1 << 2,
        }; //enum InitOption
    }// namespace init_options

typedef init_options::InitOption InitOption;

//ROS的初始化功能，在使用句柄之前必须要调用初始化函数
ROSCPP_DECL void init(int &argc, char **argv, const std::string& name, uint32_t options = 0);
ROSCPP_DECL void init(const M_string& remappings, const std::string& name, uint32_t options = 0);
ROSCPP_DECL void init(const VP_string& remapping_args, const std::string& name, uint32_t options = 0);

//检查init()函数是否被调用
ROSCPP_DECL bool isInitialized();

//检查shutdown()函数是否被调用
ROSCPP_DECL bool isShuttingDown();

//进入事件循环，每次循环均调用回调函数
ROSCPP_DECL void spin();
ROSCPP_DECL void spin(Spinner& spinner);

//事件循环一次，只调用一次回调函数
ROSCPP_DECL void spinOnce();

//等待用户 Ctrl+C 终止程序
ROSCPP_DECL void waitForShutdown();

//检测是否需要退出程序
ROSCPP_DECL bool ok();

ROSCPP_DECL void shutdown();

//节点从ROS线程中关闭的请求
ROSCPP_DECL void requestShutdown();

ROSCPP_DECL void start();

ROSCPP_DECL bool isStarted();

ROSCPP_DECL CallbackQueue* getGlobalCallbackQueue();

//搜索给定的arg参数的命令行参数。如果此参数未找到，则返回空字符串
ROSCPP_DECL std::string getROSArg(int argc, const char* const* argv, const std::string& arg);

ROSCPP_DECL void removeROSArgs(int argc, const char* const* argv, V_string& args_out);

}//namespace ros

#endif

//init.cpp  文件 中的init()函数

void init(const M_string& remappings, const std::string& name, uint32_t options){
  if (!g_atexit_registered){
    g_atexit_registered = true;
    atexit(atexitCallback);
  }

  if (!g_global_queue){
    g_global_queue.reset(new CallbackQueue);
  }

  if (!g_initialized){
    g_init_options = options;
    g_ok = true;

    ROSCONSOLE_AUTOINIT;
    // Disable SIGPIPE
#ifndef WIN32
    signal(SIGPIPE, SIG_IGN);
#endif
    //初始化network、master、this_node，file_log，分别在network.cpp,master.cpp,this_node.cpp...中有定义
    //下面几个初始化函数将在下节介绍
    network::init(remappings);
    master::init(remappings);
    this_node::init(name, remappings, options);  // name参数指的就是当前节点
    file_log::init(remappings);
    param::init(remappings);

    //初始化完成以后 全局初始化标记赋值为true
    g_initialized = true;
  }
}

//初始化函数，调用方式： ros::init(argc, argv, "node_name"); 
//还记得这条命令吗：rosrun turtlesim turtlesim_node __name:=my_turtle
//此时 argc = 4， argv = {“rosrun”，"turtlesim", "turtlesim_node", "__name:=my_turtle"}
void init(int& argc, char** argv, const std::string& name, uint32_t options){

  //数据类型M_string的定义为：typedef std::map<std::string, std::string> M_string
  M_string remappings;
  int full_argc = argc;
  // now, move the remapping argv's to the end, and decrement argc as needed
  for (int i = 0; i < argc; ){
    std::string arg = argv[i];
    size_t pos = arg.find(":="); //找到参数“__name:=my_turtle”中的 :=
    if (pos != std::string::npos){
      std::string local_name = arg.substr(0, pos);
      std::string external_name = arg.substr(pos + 2);

      ROSCPP_LOG_DEBUG("remap: %s => %s", local_name.c_str(), external_name.c_str());
      //local_name = "rosrun turtlesim turtlesim_node __name", external_name = "my_turtle"
      remappings[local_name] = external_name;

      // 参数“__name:=myturtle”移到命令的最后
      char *tmp = argv[i];
      for (int j = i; j < full_argc - 1; j++)
        argv[j] = argv[j+1];
      argv[argc-1] = tmp;
      argc--; //参数数量减1
    }
    else{
      i++; // move on, since we didn't shuffle anybody here to replace it
    }
  }

  //此时的remappings 为 {"rosrun turtlesim turtlesim_node __name":"my_turtle"}
  //调用上面的 void init(const M_string& remappings, const std::string& name, uint32_t options) 函数
  init(remappings, name, options);
}
更多special reserved keywords 可参考：http://wiki.ros.org/action/fullsearch/Remapping%20Arguments?action=fullsearch&context=180&value=linkto%3A%22Remapping+Arguments%22