C语言细致讲解线程同步的集中方式

#define THRNUM 4
static pthread_mutex_t mut[4];
static int next(int n)
{
    if(n + 1 == THRNUM)
    return 0;
    return n+1;
}
static void* pthreadfunc(void* p)
{
    int n =(int)p;
    char c = 'a' + (int)p;
    while(1)
    {
    pthread_mutex_lock(mut + n);
    write(1,&c,1);
    pthread_mutex_unlock(mut + next(n));
    }
    pthread_exit(NULL);
}
int main()
{
    int i,err;
    pthread_t tid[THRNUM];
    //创建线程
    for(i = 0 ; i < THRNUM ;i++){
        //初始化锁
        pthread_mutex_init(mut + i,NULL);
        //加锁
        pthread_mutex_lock(mut+i );
    err = pthread_create(tid+i,NULL,pthreadfunc,(void*)i );
    if(err != 0)
    {
        fprintf(stderr,"create:%s\n",strerror(err));
        exit(1);
    }
    }
    //回收线程
    pthread_mutex_unlock(mut + 0);
    alarm(5);
    for(i = 0 ; i < THRNUM ;i++){
    pthread_join(tid+i,NULL);
    }
}

#include<stdio.h>
#include<unistd.h>
#include<pthread.h>
#include<stdlib.h>
#include<string.h>
int begnum=0;
static pthread_mutex_t mut = PTHREAD_MUTEX_INITIALIZER;
static pthread_cond_t  cond = PTHREAD_COND_INITIALIZER;
typedef struct _prodinfo
{
    int num;
    struct _prodinfo *next;
}prod;
struct _prodinfo* head=NULL;
/*  条件变量可以引起阻塞并非锁
*/
void *thr_produce(void*arg)
{
    while(1)
    {
        prod* pd = malloc(sizeof(struct _prodinfo));
        pd->num=begnum++;
        pthread_mutex_lock(&mut);
        pd->next=head;
        head=pd;
        printf(" -%ld号线程生产%d产品\n",pthread_self(),pd->num);
        pthread_mutex_unlock(&mut);
        pthread_cond_signal(&cond);  
        sleep(rand()%4);
    }
}
void* thr_con(void* arg)
{
    prod* pro=NULL;
    while(1)
    {
        pthread_mutex_lock(&mut);
        while(head==NULL)
            pthread_cond_wait(&cond,&mut);
        pro = head;
        head=head->next;
        printf(" -%ld号线程消费%d产品\n",pthread_self(),pro->num);
        pthread_mutex_unlock(&mut);
        free(pro);
        sleep(rand()%4);
    }
}
int main()
{
    pthread_t cid,pid;
    int err1=pthread_create(&pid,NULL,thr_produce,NULL);
     if(err1)
        {
            fprintf(stderr,"pthread_creat():%s\n",strerror(err1));
            exit(1);
        }
    int err2=pthread_create(&cid,NULL,thr_con,NULL);
      if(err2)
        {
            fprintf(stderr,"pthread_creat():%s\n",strerror(err1));
            exit(1);
        }
    pthread_join(pid,NULL);
    pthread_join(cid,NULL);
}

int sem_init(sem_t *sem, int pshared, unsigned int value);
int sem_destroy(sem_t *sem);
Link with -pthread.

    int sem_wait(sem_t *sem);
    int sem_trywait(sem_t *sem);
    int sem_timedwait(sem_t *sem, const struct timespec *abs_timeout);

 int sem_post(sem_t *sem);

sem_t pro_sem,con_sem;
#define semcnt 5
int i=0;
int queue[semcnt];
int beginnum = 100;
void *thr_produce(void*arg)
{
    while(1)
    {
        sem_wait(&pro_sem);//生产者申请资源 pro_sem每被占用一次--一次 当为0时则阻塞
        printf("%ld 线程生产了 %d\n",pthread_self(),beginnum);
        queue[(i++)%semcnt]= beginnum++;
        sem_post(&con_sem);//为消费者的信号量释放资源pro_sem每被释放一次++一次
        sleep(rand()%4);
    }
    return NULL;
}
void* thr_con(void* arg)
{   
    int i=0;
    int num=0;
    while(1)
    {
        sem_wait(&con_sem);
        num = queue[(i++)%semcnt];
        printf("%ld 线程消费了 %d\n",pthread_self(),num);
        sem_post(&pro_sem);
        sleep(rand()%3);
    }
    return NULL;
}
int main()
{
    sem_init(&pro_sem,0,semcnt);
    sem_init(&con_sem,0,0); //消费者初始默认没有产品
    pthread_t tid[2];
     int err1=pthread_create(&tid[0],NULL,thr_produce,NULL);
     if(err1)
        {
            fprintf(stderr,"pthread_creat():%s\n",strerror(err1));
            exit(1);
        }
    int err2=pthread_create(&tid[1],NULL,thr_con,NULL);
      if(err2)
        {
            fprintf(stderr,"pthread_creat():%s\n",strerror(err1));
            exit(1);
        }
        pthread_join(tid[0],NULL);
        pthread_join(tid[1],NULL);
    sem_destroy(&pro_sem);
    sem_destroy(&con_sem);
}

pthread_rwlock_t rwlock =PTHREAD_RWLOCK_INITIALIZER;
int beginum=100;
void*thr_Wr(void*arg)
{
    while(1)
    {
        pthread_rwlock_wrlock(&rwlock);
        printf("-写线程--beginum = %d\n",beginum++);
        usleep(2000);//模拟占用时间
        pthread_rwlock_unlock(&rwlock);
        usleep(2000);//简单防止再抢锁的方法但不建议使用
    }
    return NULL;
}
void*thr_ead(void*arg)
{
    while (1)
    {
        pthread_rwlock_rdlock(&rwlock);
      printf("-读读线程--beginum = %d\n",beginum);
        usleep(2000);//模拟占用时间
       pthread_rwlock_unlock(&rwlock);
        usleep(2000);//简单防止再抢锁的方法但不建议使用
    }
    return NULL;
}
int main()
{
    int n=8,i=0;
    pthread_t tid[8];
    for(i = 0; i<5;i++)
    {
        pthread_create(&tid[i],NULL,thr_ead,NULL);
    }
     for(; i<8;i++)
    {
        pthread_create(&tid[i],NULL,thr_Wr,NULL);
    }
     for(i = 0; i<8;i++)
    {
        pthread_join(tid[i],NULL);
    }
   pthread_rwlock_destroy(&rwlock);
}