线程处理 c++ linux OS

Question

我的项目中有三个用 c++ 编写的函数。它们在同一个 .cpp 文件中，我有两个头文件。

现在，我有三个相应的线程，因此，第二个线程从第一个线程获取输出，最后一个线程等待直到第二个线程结束其操作。请注意，线程处于“永远循环”中，即while(1){....}

source.cpp 看起来像这样：

#include <iostream>
#include "source.h"
#include "glob_variables.h"
#include "armadillo"
#include <vector>
using namespace arma;
using namespace std;

void source::first_function(int size)
{
  for(int i=0;i<size;i++)
  {
   container.push_back(i);//container is global variable vector of type int declared in glob_variables.h
  }
}
//~~~~~~~~~~~~~~~~~~~~~~
void source::second_function()
{
   //sleep until the first function fills the the vector to set set its size to matrix.n_rows 
  matrix.set_size(container.size(),33);
   for(int i=0;i<container.size();i++)
   {
    for(int j=0;j<50;j++)
     {
       matrix(i,j)=i+j;//matrix is also a global variable in glob_variables.h
     }
   }
}
//~~~~~~~~~~~~~~~~~~~~~~
void source::third_function()
{
//sleep untill the second function fills the matrix, then print
cout<<matrix;//print out the matrix
}

source.h:

#include "glob_variables.h"
#include "armadillo"
#include <vector>
using namespace arma;
using namespace std;
class source
{
public:
 void first_function(int size);
 void second_function();
 void third_function();
};

glob_variables.h：

#include "armadillo"
#include <vector>
using namespace arma;
using namespace std;

extern mat matrix;
extern vector<int> container;

Main.cpp：

    #include <iostream>
    #include <stdio.h>
    #include <pthread.h>
    #include "source.h"
    #include "glob_variables.h"
    #include "armadillo"
    #include <vector>
    using namespace arma;
    using namespace std;

//thread functions
     void* first_reader(void* id1)
     {
       source mysource;
       while(1)
       {
         mysource.first_function(80);
       }
     }

     void* second_reader(void* id2)
     {
       source mysource;
       while(1)
       {
         mysource.second_function();
       }
     }

     void* third_reader(void* id3)
     {
       source mysource;
       while(1)
       {
        mysource.third_function();
       }
     }

   int main()
   {
    pthread_t first;
    pthread_t second;
    pthread_t third;

    int hndl_first;
    int hndl_second;
    int hndl_third;

    hndl_first = pthread_create(&first, NULL, first_reader, NULL);
    hndl_second= pthread_create(&second, NULL, second_thread, NULL);
    hndl_third;= pthread_create(&third, NULL,third_thread, NULL);

   pthread_exit(NULL);
   return 0; 
   }

我可以有任何技术来做到这一点，或者任何简单的例子。谢谢。

Answer 1

尝试使用以下链接。 AutoResetEvent 满足您的要求。链接中的代码正是您所期望的。

What is the C++ equivalent for AutoResetEvent under Linux?

Answer 2

我认为您想按顺序播放线程。 在第一个线程中做某事 -> 在第二个线程中做某事 -> 在第三个线程中做某事。

对吗？ 在这种情况下，您可以使用信号。

示例：

pthread_cond_t cond;
pthread_mutex_t mtx;

typedef enum {
    ready1,
    ready2,
    ready3
} thread_ready;

thread_ready t_ready;

void* first_reader(void* id1)
{
    //source mysource;
    while(1)
    {
        pthread_mutex_lock(&mtx);
        while(t_ready != ready1)
            pthread_cond_wait(&cond, &mtx);
        pthread_mutex_unlock(&mtx);

        std::cout << "first" << std::endl;
        //mysource.first_function(80);

        pthread_mutex_lock(&mtx);
        t_ready = ready2;
        pthread_cond_signal(&cond);
        pthread_mutex_unlock(&mtx);

        sleep(1);

    }
}


void* second_reader(void* id2)
{
    //source mysource;
    while(1)
    {
        pthread_mutex_lock(&mtx);
        while(t_ready != ready2)
            pthread_cond_wait(&cond, &mtx);
        pthread_mutex_unlock(&mtx);

        std::cout << "second" << std::endl;
        //mysource.second_function();

        pthread_mutex_lock(&mtx);
        t_ready = ready3;
        pthread_cond_signal(&cond);
        pthread_mutex_unlock(&mtx);

        sleep(1);
    }
}

void* third_reader(void* id3)
{
    //source mysource;
    while(1)
    {
        pthread_mutex_lock(&mtx);
        while(t_ready != ready3)
            pthread_cond_wait(&cond, &mtx);
        pthread_mutex_unlock(&mtx);

        std::cout << "third" << std::endl;
        //mysource.third_function();

        pthread_mutex_lock(&mtx);
        t_ready = ready1;
        pthread_cond_signal(&cond);
        pthread_mutex_unlock(&mtx);

        sleep(1);
    }
}


int main()
{
    pthread_t first;
    pthread_t second;
    pthread_t third;

    int hndl_first;
    int hndl_second;
    int hndl_third;

    pthread_cond_init(&cond,NULL);
    pthread_mutex_init(&mtx,NULL);

    t_ready = ready1;

    hndl_first = pthread_create(&first, NULL, first_reader, NULL);
    hndl_second = pthread_create(&second, NULL, second_reader, NULL);
    hndl_third = pthread_create(&third, NULL,third_reader, NULL);

    pthread_join(first, NULL);
    pthread_join(second, NULL);
    pthread_join(third, NULL);

    return 0;
}

其实这个case不需要做3个线程。如果你想喜欢我的代码，你最好只做 1 个线程。