mutex1.h
#ifndef __ACOUNT_H__
#define __ACOUNT_H__
#include <pthread.h>
struct Account
{
int code;
double balance; //账户余额
//定义一把互斥锁，用来对多线程操作的
//银行账户(共享资源)进行加锁保护的
//建议互斥锁用来锁定一个账户(共享资源)，和账户绑定在一起
//尽量不设置为全局变量，否则可能出现一把锁去锁定
//几百个账户，导致并发性能降低
//pthread_mutex_t mutex;
//定义读写锁
pthread_rwlock_t rwlock;
};
//创建用户
Account* create_account(int code,double balance);
//销毁账户
void destroy_account(Account* a);
//取款
double withdraw(Account* a,double amt);
//存款
double deposit(Account* a,double amt);
//查看当前余额
double get_balance(Account* a);
#endif?mutex1.cpp
#include"mutex1.h"
#include <cstdlib>
#include <pthread.h>
#include<string.h>
#include<unistd.h>
//创建账户
Account* create_account(int code,double balance)
{
Account* a=(Account*) malloc(sizeof(Account));
a->code=code;
a->balance=balance;
//对互斥锁进行初始化
//pthread_mutex_init(&a->mutex,NULL);
//对读写锁初始化
pthread_rwlock_init(&a->rwlock,NULL);
return a;
}
//销毁用户
void destroy_account(Account *a)
{
//销毁互斥锁
//pthread_mutex_destroy(&a->mutex);
//销毁读写锁
pthread_rwlock_destroy(&a->rwlock);
free(a);
}
//取款
double withdraw(Account* a,double amt)
{
//对共享资源加锁
//对共享资源操作的临界区(加锁到解锁的区域)
//pthread_mutex_lock(&a->mutex);
//加写锁
pthread_rwlock_wrlock(&a->rwlock);
if(amt<0||amt>a->balance)
{
//释放互斥锁
//pthread_mutex_unlock(&a->mutex);
//释放读写(写)锁
pthread_rwlock_unlock(&a->rwlock);
return 0.0;
}
double balance=a->balance;
sleep(1);
balance-=amt;
a->balance=balance;
//释放互斥锁
//pthread_mutex_unlock(&a->mutex);
//释方读写(写)锁
pthread_rwlock_unlock(&a->rwlock);
return amt;;
}
//存款
double deposit(Account *a, double amt)
{
//pthread_mutex_lock(&a->mutex);
pthread_rwlock_wrlock(&a->rwlock);
if(amt<0)
{
//pthread_mutex_unlock(&a->mutex);
pthread_rwlock_wrlock(&a->rwlock);
return 0.0;
}
double balance=a->balance;
sleep(1);
balance+=amt;
a->balance=balance;
//pthread_mutex_unlock(&a->mutex);
pthread_rwlock_unlock(&a->rwlock);
return amt;
}
//查看当前余额
double get_balance(Account *a)
{
//pthread_mutex_lock(&a->mutex);
pthread_rwlock_rdlock(&a->rwlock);
double balance=a->balance;
//pthread_mutex_unlock(&a->mutex);
pthread_rwlock_rdlock(&a->rwlock);
return balance;
}main.cpp
#include "mutex1.h"
#include <cstdio>
#include<iostream>
#include <pthread.h>
#include <string>
using namespace std;
pthread_mutex_t mt;
//pthread_mutex_init(&mt,NULL);
struct OperArg //操作者信息
{
string name;
Account *account;
double amt;
};
//定义取款操作的线程运行函数
void* withdraw_fn(void* arg)
{
OperArg* oa=(OperArg*)arg;
double amt=withdraw(oa->account,oa->amt);
pthread_mutex_lock(&mt);
cout<<oa->name<<" "<<
" withdraw "<<amt<< " from account "<<
oa->account->code<<endl; //amt 是取款函数的返回值
pthread_mutex_unlock(&mt);
return (void*)0;
}
//定义存款操作的线程运行函数
void* deposit_fn(void* arg)
{
OperArg* oa=(OperArg*)arg;
double amt=deposit(oa->account,oa->amt);
cout<<"name:"<<oa->name<<" "<<pthread_self()<<
" withdraw "<<amt<< " from account "<<
oa->account->code<<endl; //amt 是取款函数的返回值
return (void*)0;
}
//定义检查银行账户的线程运行函数
void* check_fn(void* arg)
{
return (void*)0;
}
int main()
{
int err;
pthread_t boy,girl;
Account *a=create_account(100001,10000); //创建银行用户
OperArg o1,o2; //操作的两个用户,boy,girl
o1.name="boy";
o1.account=a;
o1.amt=10000;
o2.name="girl";
o2.account=a;
o2.amt=10000;
//启动两个子线程(boy和girl线程)
//同时去操作一个银行用户
err=pthread_create(&boy,NULL,withdraw_fn,(void*)&o1);
if(err!=0)
{
perror("create error");
}
err=pthread_create(&girl,NULL,withdraw_fn,(void*)&o2);
if(err!=0)
{
perror("create error");
}
pthread_join(boy,NULL);
pthread_join(girl,NULL);
//两个子线程操作完后，主线程去查看余额
cout<<"account balance: "<<get_balance(a)<<endl;
destroy_account(a);
return 0;
}?
