The low-level D-Bus C API学习笔记（二）收发测试

开辟两个线程，一个负责发送消息，另一个负责接收.
源码如下：
main.c

#include 
#include "DBus.h"
#include 
#include 

using namespace std;

void send()
{
    DBusError error;
    DBusConnection* connection;
    DBusMessage * msg;
    DBusMessageIter iter;
    dbus_uint32_t  serial =0;
    int ret;
    int64_t  count = 0;

    //1.建立连接
    dbus_error_init(&error);

    connection = dbus_bus_get(DBUS_BUS_SESSION, &error);
    if(dbus_error_is_set(&error)){
        fprintf(stderr, "Connection Error (%s)\n", error.message);
        dbus_error_free(&error);
    }
    if(connection == NULL)
    {
        fprintf(stderr,"connection == NULL\n");
        return ;
    }

    //2.注册well-known公共名 用户独占名称
    ret = dbus_bus_request_name(connection,"test.singal.source",DBUS_NAME_FLAG_REPLACE_EXISTING,&error);
    if(dbus_error_is_set(&error)){
        fprintf(stderr,"Name Err :%s\n",error.message);
        dbus_error_free(&error);
    }
    if(ret !=DBUS_REQUEST_NAME_REPLY_PRIMARY_OWNER) {
        fprintf(stderr,"OWNER REPEAT\n");
        return ;
    }
    while(1)
    {

        //３.发送信号
        //构造表示信号发射的新消息
        if((msg =dbus_message_new_signal("/test/signal/Object","test.signal.Type","Test"))== NULL){
            fprintf(stderr,"MessageNULL\n");
            return ;
        }
        //给这个信号（messge）具体的内容
        char * sigvalue = "hello world";
        dbus_message_iter_init_append(msg,&iter);
        if(!dbus_message_iter_append_basic(&iter,DBUS_TYPE_STRING,&sigvalue)){
            fprintf(stderr,"Out OfMemory!\n");
            return ;
        }
        if( !dbus_connection_send(connection,msg,&serial)){
            fprintf(stderr,"Out of Memory!\n");
            return ;
        }
        dbus_connection_flush(connection);
        //printf("Signal Send\n");
        cout << "Send msg:" << ++count << endl;
        sleep(2);
    }
        //步骤5: 释放相关的分配的内存。
        dbus_message_unref(msg );
}

void listen()
{
    while(1)
    {
        DBusMessage * msg;
        DBusMessageIter iter;
        DBusConnection * connection;
        DBusError error;
        int ret;
        char * sigvalue;
        int64_t  count = 0;

        //1.建立连接
        dbus_error_init(&error);

        connection = dbus_bus_get(DBUS_BUS_SESSION, &error);
        if(dbus_error_is_set(&error)){
            fprintf(stderr, "Connection Error (%s)\n", error.message);
            dbus_error_free(&error);
        }
        if(connection == NULL)
        {
            fprintf(stderr,"connection == NULL\n");
            return ;
        }

        //2.注册well-known公共名 用户独占名称
        ret = dbus_bus_request_name(connection,"test.singal.dest",DBUS_NAME_FLAG_REPLACE_EXISTING,&error);
        if(dbus_error_is_set(&error)){
            fprintf(stderr,"Name Err :%s\n",error.message);
            dbus_error_free(&error);
        }
        if(ret !=DBUS_REQUEST_NAME_REPLY_PRIMARY_OWNER) {
            fprintf(stderr,"OWNER REPEAT\n");
            return ;
        }

        //步骤3:通知D-Bus daemon，希望监听来行接口test.signal.Type的信号
        dbus_bus_add_match(connection,"type='signal',interface='test.signal.Type'",&error);
        //实际需要发送东西给daemon来通知希望监听的内容，所以需要flush
        dbus_connection_flush(connection);
        if(dbus_error_is_set(&error)){
            fprintf(stderr,"Match Error%s\n",error.message);
            dbus_error_free(&error);
        }

        //步骤4:在循环中监听，每隔开1秒，就去试图自己的连接中获取这个信号。这里给出的是中连接中获取任何消息的方式，所以获取后去检查一下这个消息是否我们期望的信号，并获取内容。我们也可以通过这个方式来获取method call消息。
        while(1){
            dbus_connection_read_write(connection,0);//这里会浪费cpu资源
            msg =dbus_connection_pop_message (connection);
            if(msg == NULL){
                //cout << "Idle state" << endl;
                sleep(1);
                continue;
            }

            if(dbus_message_is_signal(msg,"test.signal.Type","Test")){
                if(!dbus_message_iter_init(msg,&iter))
                    fprintf(stderr,"MessageHas no Param");
                else if(dbus_message_iter_get_arg_type(&iter)!= DBUS_TYPE_STRING)
                    cout << "Param is not string" << endl;
                else
                    dbus_message_iter_get_basic(&iter,&sigvalue);
                //printf("Got Singal withvalue : %s\n",sigvalue);
                cout << "Receive msg:" << ++count << endl;
            }
            dbus_message_unref(msg);
        }
    }
}
int main() {
    std::thread th1(send);
    std::thread th2(listen);
    th1.join();
    th2.join();
    return 0;
}

头文件DBus.h

#ifndef DBUS_TEST_DBUS_H
#define DBUS_TEST_DBUS_H

#include 
#include 
#include 

class DBus {

};


#endif //DBUS_TEST_DBUS_H