LinuxC/C++编程基础(8) 基于条件变量实现生产者与消费者的实例

一.buffer.h的声明，如下：

#ifndef BUFFER_H

#define BUFFER_H

#include <iostream>

#include <boost/thread/mutex.hpp>

#include <boost/thread/condition_variable.hpp>

#include <stack>

class buffer{

public:

buffer(size_t n):unRead(0),capacity(n){}

void put(int x);

void get(int* x);

private:

bool is_full();

bool is_empty();

private:

boost::mutex mu;

boost::condition_variable_any putCond;

boost::condition_variable_any getCond;

std::stack<int> stk;

int unRead;

int capacity;

};

inline bool buffer::is_full(){

return unRead == capacity;

}

inline bool buffer::is_empty(){

return unRead == 0;

}

#endif

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二.buffer.cpp的实现，如下：

#include "buffer.h"

boost::mutex io_mu;

void buffer::put(int x)

{

{

boost::mutex::scoped_lock lock(mu);

while(is_full())

{

{

boost::mutex::scoped_lock lock(io_mu);//io流是共享资源，不是线程安全的，故需要锁定，以下同理。

std::cout<<"stack is full,please wait..."<<std::endl;

}

putCond.wait(mu);

}

stk.push(x);

++unRead;

}

getCond.notify_one();

}

void buffer::get(int* x)

{

{

boost::mutex::scoped_lock lock(mu);

while(is_empty())

{

{

boost::mutex::scoped_lock lock(io_mu);

std::cout<<"stack is empty,please wait..."<<std::endl;

}

getCond.wait(mu);

}

--unRead;

*x = stk.top();

stk.pop();

}

putCond.notify_one();

}

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三.main.cpp的实现，如下：

#include <boost/thread/thread.hpp>

#include <string>

#include "buffer.h"

extern boost::mutex io_mu;

buffer buf(5);

void producer(int n,std::string str,int seq)

{

for(int i=0;i<n;++i)

{

{

boost::mutex::scoped_lock lock(io_mu);

std::cout<<"["<<str<<"->"<<seq<<"]"<<" put data "<<i<<std::endl;

}

buf.put(i);

sleep(1);

}

}

void consumer(int n,std::string str,int seq)

{

int x;

for(int i=0;i<n;++i)

{

buf.get(&x);

boost::mutex::scoped_lock lock(io_mu);

std::cout<<"["<<str<<"->"<<seq<<"]"<<" get data "<<x<<std::endl;

sleep(1);

}

}

int main(int argc,char** argv)

{

boost::thread t1(producer,10,"producer",1);

boost::thread t2(consumer,5,"consumer",1);

boost::thread t3(consumer,5,"consumer",2);

t1.join();

t2.join();

t3.join();

return 0;

}

说明：代码简洁明了，无需赘述。

四.可能会出现的问题，如下：

undefined reference to `boost::thread_resource_error::thread_resource_error()'

说明：该问题其实很好解决，当然也得看具体情况，这里略去。

五.makefile的编写请参考前一篇

参考文献：boost库完全开发指南，罗剑锋 著

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