Thread_local_global_variable

最新推荐文章于 2023-01-20 15:47:40 发布

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本文提供了一个使用pthread线程库实现线程局部存储(TLS)的C语言示例程序。该程序创建了两个线程，并为每个线程分配了独立的数据结构。通过设置和获取特定于线程的数据，演示了TLS的基本用法。

1 Thread-specific data

2 Thread local storage

准备中...

    #include <stdio.h>
    #include <stdlib.h>
    #include <pthread.h>
    #include <string.h>
     
    pthread_key_t key;
    pthread_key_t key2;
     
    struct test_struct {
    int i;
    float k;
    }struct_data;
     
    int temp;
    void destroykey(void *td) {
     
    pthread_setspecific (key, NULL);
    free(td);
     
    }
    void destroykey2(void *temp) {
    pthread_setspecific (key2, NULL);
    free(temp);
    }
    int setspecificvar () {
    int *temp = malloc(sizeof(int));
    struct test_struct *td = malloc(sizeof(struct test_struct));
    memset(td, 0, sizeof(struct test_struct));
    memset(temp, 0, sizeof(int));
    pthread_setspecific (key, td);
    pthread_setspecific (key2, temp);
     
    return 0;
    }
    int changedata (int i, float k, int tempvar) {
     
    int *temp = pthread_getspecific(key2);
    *temp = tempvar;
    struct test_struct *td1 = pthread_getspecific(key);
    td1->i = i;
    td1->k = k;
    return 0;
    }
     
    int printdata (int t) {
     
    int *temp = pthread_getspecific(key2);
    struct test_struct *td1 = pthread_getspecific(key);
     
    printf ("The addres in child%d returned from pthread_getspecific(key):0x%p\n", t, (struct test_struct *)pthread_getspecific(key));
     
    printf ("The value of members in structure bound to \"key\" in child%d:\nstruct_data.i:%d\nstruct_data.k: %f\n", t, td1->i, td1->k);
     
    printf ("------------------------------------------------------\n");
     
    printf ("The addres in child%d returned from pthread_getspecific(key2):0x%p\n", t, (int *)pthread_getspecific(key2));
    printf ("The value of \"temp\" bound to \"key2\" in child%d:%d\n", t, *temp);
     
    return 0;
    }
     
    void *child1 (void *arg) {
    setspecificvar ();
    changedata(10, 3.141500, 110);
    printdata(1);
    }
     
    void *child2 (void *arg) {
     
    setspecificvar ();
     
    changedata(211, 2.141500, 211);
    printdata(2);
     
    changedata (222, 22.141500, 2222);
    printdata (2);
    }
     
    int create_key () {
    pthread_key_create (&key, destroykey);
    pthread_key_create (&key2, destroykey2);
    return 0;
    }
     
    int delete_key () {
     
    pthread_key_delete (key);
    pthread_key_delete (key2);
    return 0;
    }
     
    int main (int argc, char *argv[]) {
    pthread_t tid1, tid2;
     
    create_key ();
    pthread_create (&tid1, NULL, (void *)child1, NULL);
    pthread_create (&tid2, NULL, (void *)child2, NULL);
    pthread_join (tid1, NULL);
    pthread_join (tid2, NULL);
     
    delete_key ();
     
    return 0;
    }

参考：

http://stackoverflow.com/questions/14260668/how-to-use-thread-specific-data-correctly

http://publib.boulder.ibm.com/infocenter/iseries/v5r3/index.jsp?topic=%2Frzahw%2Frzahwe21rx.htm

http://cboard.cprogramming.com/c-programming/153492-thread-specific-data-not-work-fine-me-pthread.html