4月「掘金·日新计划」第9天
一、相关函数
进程函数包含3点：线程，互斥锁，条件
二、实践使用
pthread库，编译-pthread
2.1、线程pthread_create,pthread_exit,pthread_join,pthread_self,pthread_equal
#include <pthread.h>
int pthread_create(pthread_t *thread, const pthread_attr_t *attr,void *(*start_routine) (void *), void *arg);
功能：创建线程
参数：
- pthread_t指针t1
- 线程属性，NULL
- 函数指针，线程执行的函数
- 传递数据，无类型数据（可以传结构体数据）
返回值：成功0，错误错误编号
void pthread_exit(void *retval);
功能：退出线程
参数：无类型指针，线程退出传的数据，要保证内存不释放，static关键字
int pthread_join(pthread_t thread, void **retval);
功能：等待，主函数阻塞等待线程退出
参数：
- t1
- 退出返回值，二级指针，就是退出函数的参数
pthread_t pthread_self(void);
功能：返回线程id
返回值：长整形，%ld
int pthread_equal(pthread_t t1, pthread_t t2);
功能：id比较
返回值：相等非0，否则0
例子:
- 创建线程
- 编写线程函数，输出主函数的值（结构体指针数组）和线程id，退出返回一个数据
- 主函数，输出id，等待线程，输出线程退出的数
- 注:编译加－lpthread
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
typedef struct Student{
int arg;
char name[12];
struct Student *next;
}student;
//线程执行函数
void *fun1(void *ar)
{
static char *ptr = "wei"; //返回数据，要static防止释放
student **p = (student **)ar; //要用二级指针，因为数组里面还是地址
printf("t1:arg1=%d\n",p[0]->arg); //打印，结构体里的内容
// student *p = *(student **)ar;
// printf("t1:arg1=%d\n", p->arg);
printf("t1:name1=%s\n",p[0]->name);
printf("t1:arg2=%d\n",p[1]->arg);
printf("t1:name2=%s\n",p[1]->name);
printf("t1:id=%ld\n",(unsigned long)pthread_self()); //打印id
pthread_exit((void *)ptr); //退出线程，返回ptr数据
}
int main()
{
pthread_t t1;
student s1={21,"xiao"}; //定义2个结构体变量
student s2={30,"wei"};
student *array[2]={&s1, &s2}; //放入结构体指针数组
int arg = 100; //
char *a = NULL; //线程退出，数据接收指针
if(pthread_create(&t1, NULL, fun1, (void *)array) == 0){ //创建线程，传入指针数组
printf("found thread succeed\n");
}
printf("main:id=%ld\n",(unsigned long)pthread_self()); //打印id
pthread_join(t1, (void **)&a); //等待线程退出，阻塞
printf("main:t1 exit,%s\n",(char*)a); //打印线程退出返回的数据
return 0;
}
/*
found thread succeed
main:id=139959759869760
t1:arg1=21
t1:name1=xiao
t1:arg2=30
t1:name2=wei
t1:id=139959759865600
main:t1 exit,wei
*/
2.2、互斥锁pthread_mutex_init，pthread_mutex_destroy，pthread_mutex_lock，pthread_mutex_unlock
int pthread_mutex_init(pthread_mutex_t *restrict mutex，const pthread_mutexattr_t *restrict attr)
功能：创建锁
参数：
- 全局变量，指针
- 属性，NULL
int pthread_mutex_destroy(pthread_mutex_t *mutex)
功能：销毁锁
参数：全局变量，指针
int pthread_mutex_lock(pthread_mutex_t *mutex)
功能：加锁
参数：全局变量，指针
int pthread_mutex_unlock(pthread_mutex_t *mutex)
功能：解锁
参数：全局变量，指针
例子:
-
全局变量data和锁变量
-
创建锁，创建2个线程
-
2线程函数
-
1: 加锁，循环data++，sleep延时1s，if3解锁退出线程
-
2:死循环输出data，加锁data++，解锁，延时1s
-
主函数，打印data，等待线程
-
销毁锁
注:线程2加锁是因为锁被线程1拿了，没有锁拿就会卡在那里。
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <unistd.h>
int data = 0;
pthread_mutex_t nutex;
void *fun1(void *arg)
{
printf("t1:id=%ld\n",(unsigned long)pthread_self());
pthread_mutex_lock(&nutex);
while(1){
data++;
printf("t1:data=%d\n",data);
if(data == 3){
printf("t1 quit =============================\n");
pthread_mutex_unlock(&nutex);
pthread_exit(NULL);
}
sleep(1);
}
}
void *fun2(void *arg)
{
printf("t2:id=%ld\n",(unsigned long)pthread_self());
while(1){
pthread_mutex_lock(&nutex);
data++;
pthread_mutex_unlock(&nutex);
printf("t2:data=%d\n",data);
sleep(1);
}
pthread_exit(NULL);
}
int main()
{
pthread_t t1;
pthread_t t2;
int arg = 100;
pthread_mutex_init(&nutex, NULL);
if(pthread_create(&t1, NULL, fun1, (void *)&arg) == 0){
printf("found thread succeed\n");
}
if(pthread_create(&t2, NULL, fun2, (void *)&arg) == 0){
printf("found thread succeed\n");
}
printf("main:id=%ld\n",(unsigned long)pthread_self());
while(1){
printf("main:%d\n",data);
sleep(1);
}
pthread_join(t1,NULL);
pthread_join(t2,NULL);
pthread_mutex_destroy(&nutex);
return 0;
}
/*
found thread succeed
t1:id=140562014590720
t1:data=1
found thread succeed
main:id=140562023094080
main:1
t2:id=140562006198016
main:1
t1:data=2
t1:data=3
t1 quit =============================
main:2
t2:data=4
main:4
t2:data=5
t2:data=6
main:6
*/
2.3、条件pthread_cond_init，pthread_cond_destroy，pthread_cond_wait，pthread_cond_timewait，pthread_cond_signal，pthread_cond_broadcast
静态态初始化，pthread_cond_t cond = PTHREAD_COND_INITIALIER;
动态初始化，int pthread_cond_init(pthread_cond_t *cond, thread_condattr_t *cond_attr);
功能：创建
参数：全局变量，指针属性NULL
int pthread_cond_destroy(pthread_cond_t *cond);
功能：销毁
int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex);
int pthread_cond_timewait(pthread_cond_t *cond,pthread_mutex *mutex,const timespec *abstime);
功能：等待
参数：cond，nutex
int pthread_cond_signal(pthread_cond_t *cond);
int pthread_cond_broadcast(pthread_cond_t *cond);
功能：触发，广播
例子：
- 2个线程，锁，条件初始化
- 线程1等待条件
- 线程2加锁data++，触发条件
- 线程1执行
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <unistd.h>
int data = 0;
pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
pthread_mutex_t nutex = PTHREAD_MUTEX_INITIALIZER;
void *fun1(void *arg)
{
while(1){
pthread_cond_wait(&cond, &nutex);
printf("t1:%d\n",data);
data = 0;
}
}
void *fun2(void *arg)
{
while(1){
pthread_mutex_lock(&nutex);
data++;
pthread_mutex_unlock(&nutex);
printf("t2:data=%d\n",data);
if(data == 3){
pthread_cond_signal(&cond);
}
sleep(1);
}
pthread_exit(NULL);
}
int main()
{
pthread_t t1;
pthread_t t2;
pthread_mutex_init(&nutex, NULL);
pthread_create(&t1,NULL,fun1,NULL);
pthread_create(&t2,NULL,fun2,NULL);
pthread_join(t1,NULL);
pthread_join(t2,NULL);
pthread_cond_destroy(&cond);
pthread_mutex_destroy(&nutex);
return 0;
}
/*
t2:data=1
t2:data=2
t2:data=3
t1:3
t2:data=1
t2:data=2
t2:data=3
t1:3
t2:data=1
t2:data=2
t2:data=3
t1:3
*/
