Linux多线程编程（一）

#include<pthread.h>
int pthread_create (pthread_t *__restrict __newthread,//新创建的线程ID
			  __const pthread_attr_t *__restrict __attr,//线程属性
			  void *(*__start_routine) (void *),//新创建的线程从start_routine开始执行
			  void *__restrict __arg)//执行函数的参数

#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <unistd.h>
#include <string.h>

int num=0;
void *add(void *arg) {//线程执行函数，执行500次加法
  int i = 0,tmp;
  for (; i <500; i++)
  {
    tmp=num+1;
    num=tmp;
    printf("add+1,result is:%d\n",num);
  }
  return ((void *)0);
}
void *sub(void *arg)//线程执行函数，执行500次减法
{
  int i=0,tmp;
  for(;i<500;i++)
  {
    tmp=num-1;
    num=tmp;
    printf("sub-1,result is:%d\n",num);
  }
  return ((void *)0);
}
int main(int argc, char** argv) {
  
  pthread_t tid1,tid2;
  int err;
  void *tret;
  err=pthread_create(&tid1,NULL,add,NULL);//创建线程
  if(err!=0)
  {
    printf("pthread_create error:%s\n",strerror(err));
    exit(-1);
  }
  err=pthread_create(&tid2,NULL,sub,NULL);
  if(err!=0)
  {
    printf("pthread_create error:%s\n",strerror(err));
     exit(-1);
  }
  err=pthread_join(tid1,&tret);//阻塞等待线程id为tid1的线程，直到该线程退出
  if(err!=0)
  {
    printf("can not join with thread1:%s\n",strerror(err));
    exit(-1);
  }
  printf("thread 1 exit code %d\n",(int)tret);
  err=pthread_join(tid2,&tret);
  if(err!=0)
  {
    printf("can not join with thread1:%s\n",strerror(err));
    exit(-1);
  }
  printf("thread 2 exit code %d\n",(int)tret);
  return 0;
}

#include<pthread.h>
int pthread_mutex_init (pthread_mutex_t *__mutex,
			    __const pthread_mutexattr_t *__mutexattr);
int pthread_mutex_destroy (pthread_mutex_t *__mutex);

#include<pthread.h>
int pthread_mutex_lock (pthread_mutex_t *__mutex)；
int pthread_mutex_unlock (pthread_mutex_t *__mutex)；

pthread_mutex_t mylock=PTHREAD_MUTEX_INITIALIZER;
void *add(void *arg) {
  int i = 0,tmp;
  for (; i <500; i++)
  {
    pthread_mutex_lock(&mylock);
    tmp=num+1;
    num=tmp;
    printf("+1,result is:%d\n",num);
    pthread_mutex_unlock(&mylock);
  }
  return ((void *)0);
}
void *sub(void *arg)
{
  int i=0,tmp;
  for(;i<500;i++)
  {
    pthread_mutex_lock(&mylock);
    tmp=num-1;
    num=tmp;
    printf("-1,result is:%d\n",num);
    pthread_mutex_unlock(&mylock);
  }
  return ((void *)0);
}

#include<pthread.h>
int pthread_rwlock_init (pthread_rwlock_t *__restrict __rwlock,
				__const pthread_rwlockattr_t *__restrict
				__attr);
int pthread_rwlock_destroy (pthread_rwlock_t *__rwlock);

#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <unistd.h>
#include <string.h>
#define DEBUG 1

int num=0;
pthread_mutex_t mylock=PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t qready=PTHREAD_COND_INITIALIZER;
void * thread_func(void *arg)
{
  int i=(int)arg; 
  int ret;
  sleep(5-i);//线程睡眠,然最先生成的线程，最后苏醒
  pthread_mutex_lock(&mylock);//调用pthread_cond_wait前，必须获得互斥锁
  while(i!=num)
  {
#ifdef DEBUG
    printf("thread %d waiting\n",i);
#endif
    ret=pthread_cond_wait(&qready,&mylock);//该函数把线程放入等待条件的线程列表，然后对互斥锁进行解锁，这两部都是原子操作。并且在pthread_cond_wait返回时，互斥量再次锁住。
    if(ret==0)
    {
#ifdef DEBUG
      printf("thread %d wait success\n",i);
#endif
    }else
    {
#ifdef DEBUG
      printf("thread %d wait failed:%s\n",i,strerror(ret));
#endif
    }
  }
  printf("thread %d is running \n",i);
  num++;
  pthread_mutex_unlock(&mylock);//解锁
  pthread_cond_broadcast(&qready);//唤醒等待该条件的所有线程
  return (void *)0;
}
int main(int argc, char** argv) {
  
  int i=0,err;
  pthread_t tid[4];
  void *tret;
  for(;i<4;i++)
  {
    err=pthread_create(&tid[i],NULL,thread_func,(void *)i);
    if(err!=0)
    {
      printf("thread_create error:%s\n",strerror(err));
      exit(-1);
    }
  }
  for (i = 0; i < 4; i++)
  {
    err = pthread_join(tid[i], &tret);
    if (err != 0)
    {
      printf("can not join with thread %d:%s\n", i,strerror(err));
      exit(-1);
    }
  }
  return 0;
}