Question

我有以下代码（我删除了一些不相关的部分）

使用此代码，我可以使“connect_ip”中的线程不再启动，但当前的线程仍在运行，我也想停止它们（只有“connect_ip”中的那些）

struct domain_list {
    char domain[20];
    struct domain_list * next;
};
typedef struct arg_struct {
    unsigned long ip;
    char domain[30];
    int X;
    int stop;
}arg_struct;
struct domain_list * first_domain = NULL;

int main()
{
    //loading into structure from file code is missing


    for(i = 0 ; i < number_thread; i++)
    {
        if(pthread_create(&thread_id[i],NULL,&start,NULL) != 0)
        {
            i--;
            fprintf(stderr,RED "\nError in creating thread\n" NONE);
        }
    }
    for(i = 0 ; i < number_thread; i++)
        if(pthread_join(thread_id[i],NULL) != 0)
        {
            fprintf(stderr,RED "\nError in joining thread\n" NONE);
        }
}


void * start(void * data)
{
    unsigned long ip = 0xffffffff;
    char ip[20];
    while (!feof(INFILE))
    {
        if (fgets(ip,sizeof(ip),INFILE) != NULL)
        {
            if (strlen(ip) < 8)
                break;
            if (ip[strlen (ip) - 1] == '\n')
                ip[strlen (ip) - 1] = '\0';
            ip = ntohl((unsigned long)inet_addr(ip));
        }
        connect_ip(ip);
    }
    return NULL;
}


void connect_ip(unsigned long ip)
{
    struct domain_list * curr_domain = first_domain;
    int exit=0,stop=0;
    while(curr_domain)
    {
        for(t = 0 ; t < ip_thread; t++)
        {
            pthread_mutex_lock(&thrd_list);
            arg_struct *args = calloc(1, sizeof(*args));
            strncpy(args->domain,curr_domain->domain,sizeof(args->domain) - 1);
            args->ip = ip;
            args->X = ex;
            args->stop = stop;
            pthread_mutex_unlock(&thrd_list);
            if(pthread_create(&thread_id[t],NULL,checkip,args) != 0)
            {
                t--;
                fprintf(stderr,RED "\nError in creating thread\n" NONE);
            }
            else
            {
                pthread_mutex_lock(&thrd_list);
                if(curr_domain->next != NULL)
                    curr_domain = curr_domain->next;
                else
                    exit = 1;
                pthread_mutex_unlock(&thrd_list);
            }
        }

        for(t = 0 ; t < ip_thread; t++)
        {
            void *join_result;
            if(pthread_join(thread_id[t],&join_result) != 0)
            {
                fprintf(stderr,RED "\nError in joining thread\n" NONE);
            }
            else
            {
                arg_struct *args = join_result;
                stop = args->stop;
                free(args);
            }
        }
        if (exit == 1 || stop == 1)
            break;
    }//end while

}

void *checkip(void *arguments)
{
    arg_struct *args = arguments;
    if (args->X == 1)
        return args;
    int sock = 0,ex = 0,ret = 0;
    struct in_addr t_in;
    t_in.s_addr = ntohl(args->ip);
    sock = check_port(args->ip,80);
    if(sock == -1)
    {
        args->X = 1;
        return args;
    }

//some code missing

    if(ret == 1)
        args->stop = 1;
    return args;
}

第一个问题是如何使“connect_ip”中的所有线程在void“checkip”中的ret = 1时停止，而不影响“start”中的其他线程？

第二个问题是在这种情况下如何正确使用pthread_mutex_lock所以线程从“开始”和那些来自“connect_ip”来搞乱数据？

Answer 1

两个快速观察。首先，你为什么要在for循环中这样做：“我 - ;”。因此，线程标识符可能位于thread_id数组中的不同索引中。第二，同样的“t--”在connect_ip（）函数中。这可能导致pthread_join（）在执行pthread_join（）时引用不正确的线程ID。

请在评论中查找其他文字。

添加一个快速示例，允许各个connect_Ip线程在其子线程中维护一个公共信号变量。该示例人工设置connect_ip线程的全局变量和索引1.这样，一旦设置了信号，connect_ip线程的所有（三个）子线程都会停止。另一方面，另一个父线程（带索引0的connect_ip）继续运行：

#include <stdio.h>
#include <pthread.h>

#define TEMP_MAX_THREADS 2
#define TEMP_MAX_CHILD_THREADS 3

int stop[TEMP_MAX_THREADS];

typedef struct two_ints_ {
    int parent_index;
    int child_index;
    int *common_stop_all_children;
} two_ints;

void *check_ip (void *arg) {
    int i = 0, temp;
    two_ints *x = (two_ints *)arg;
    printf("\t%s Starting to run (index: %d parent: %d) \n",
            __FUNCTION__, x->child_index, x->parent_index);
    srand(time(NULL));
    while (i++ < 10){
        printf("\t%s Me wokeup (index: %d parent: %d) \n",
                __FUNCTION__, x->child_index, x->parent_index);
        sleep(1);
        if (x->parent_index == 1) {
            if (*(x->common_stop_all_children) == 1) {
                printf("\t%s Other thread has set the stop signal (index: %d parent: %d). Return\n",
                        __FUNCTION__, x->child_index, x->parent_index);
                return;
            }
            temp = rand() % 4;
            if (temp == 2) {
                printf("\t%s Time to return. Let us set the global stop to 1 (index: %d parent: %d) \n",
                        __FUNCTION__, x->child_index, x->parent_index);
                *(x->common_stop_all_children) = 1;
                return;
            }
        }
    }
    return NULL;
}

void *connect_ip (void *arg) {
    int common_stop_all_children = 0;
    pthread_t child_thread_id[TEMP_MAX_CHILD_THREADS];
    two_ints arg_two_ints[TEMP_MAX_CHILD_THREADS];
    int i;

    printf("I am here with index: %d \n", *(int *)arg);
    for(i = 0 ; i < TEMP_MAX_CHILD_THREADS; i++) {
        arg_two_ints[i].parent_index = *(int *)arg;
        arg_two_ints[i].child_index = i;
        arg_two_ints[i].common_stop_all_children = &common_stop_all_children;

        if(pthread_create(&child_thread_id[i], NULL, check_ip, (void*) &arg_two_ints[i]) != 0) {
            fprintf(stderr, "\nError in creating thread\n" );
        }
    }

    for(i = 0 ; i < TEMP_MAX_CHILD_THREADS; i++) {
        if(pthread_join(child_thread_id[i], NULL) != 0) {
            fprintf(stderr, "\npthread_join failed\n" );
        }
    }

    return NULL;
}

int main() {
    pthread_t thread_id[TEMP_MAX_THREADS];
    int index[TEMP_MAX_THREADS];
    int i;

    for(i = 0 ; i < TEMP_MAX_THREADS; i++) {
        index[i] = i;
        if(pthread_create(&thread_id[i], NULL, connect_ip, (void *)&index[i]) != 0) {
            fprintf(stderr, "\nError in creating thread\n" );
        }
    }

    for(i = 0 ; i < TEMP_MAX_THREADS; i++) {
        if(pthread_join(thread_id[i], NULL) != 0) {
            fprintf(stderr, "\npthread_join failed\n");
        }
    }

}

以下是输出示例。

$ ./a.out
I am here with index: 1
I am here with index: 0
    check_ip Starting to run (index: 0 parent: 1)
    check_ip Starting to run (index: 1 parent: 1)
    check_ip Me wokeup (index: 0 parent: 1)
    check_ip Starting to run (index: 0 parent: 0)
    check_ip Starting to run (index: 2 parent: 1)
    check_ip Me wokeup (index: 1 parent: 1)
    check_ip Starting to run (index: 1 parent: 0)
    check_ip Starting to run (index: 2 parent: 0)
    check_ip Me wokeup (index: 0 parent: 0)
    check_ip Me wokeup (index: 2 parent: 1)
    check_ip Me wokeup (index: 1 parent: 0)
    check_ip Me wokeup (index: 2 parent: 0)
    check_ip Me wokeup (index: 2 parent: 1)
    check_ip Me wokeup (index: 0 parent: 0)
    check_ip Time to return. Let us set the global stop to 1 (index: 1 parent: 1)
    check_ip Me wokeup (index: 1 parent: 0)
    check_ip Me wokeup (index: 2 parent: 0)
    check_ip Me wokeup (index: 0 parent: 1)
    check_ip Me wokeup (index: 2 parent: 0)
    check_ip Other thread has set the stop signal (index: 2 parent: 1). Return
    check_ip Me wokeup (index: 0 parent: 0)
    check_ip Me wokeup (index: 1 parent: 0)
    check_ip Other thread has set the stop signal (index: 0 parent: 1). Return
    check_ip Me wokeup (index: 2 parent: 0)
    check_ip Me wokeup (index: 0 parent: 0)
    check_ip Me wokeup (index: 1 parent: 0)
    check_ip Me wokeup (index: 1 parent: 0)
    check_ip Me wokeup (index: 0 parent: 0)
    check_ip Me wokeup (index: 2 parent: 0)
    check_ip Me wokeup (index: 2 parent: 0)
    check_ip Me wokeup (index: 1 parent: 0)
    check_ip Me wokeup (index: 0 parent: 0)
    check_ip Me wokeup (index: 2 parent: 0)
    check_ip Me wokeup (index: 0 parent: 0)
    check_ip Me wokeup (index: 1 parent: 0)
    check_ip Me wokeup (index: 2 parent: 0)
    check_ip Me wokeup (index: 1 parent: 0)
    check_ip Me wokeup (index: 0 parent: 0)
^C

线程标志，以阻止他人和多胎面碰撞

1 个答案: