C++ boost asio 学习（一）

跟着 http://www.boost.org/doc/libs/1_53_0/doc/html/boost_asio/tutorial.html 学习asio。


编译的时候需要加上 -lboost_system

同步定时器例子

#include <iostream>
#include <boost/asio.hpp>
#include <boost/date_time/posix_time/posix_time.hpp>

using namespace std;

void tuttimer1()
{
	boost::asio::io_service io;

	// 等待5秒
	boost::asio::deadline_timer t(io, boost::posix_time::seconds(5));

	t.wait();
}


int main() {
	tuttimer1();
	cout << "!!!Hello World!!!" << endl; // prints !!!Hello World!!!

	return 0;
}

异步定时器例子

#include <iostream>
#include <boost/asio.hpp>
#include <boost/date_time/posix_time/posix_time.hpp>

// 定义回调函数，asio库要求回调函数只能有一个参数，且为 const boost::system::error_code & 类型
void print(const boost::system::error_code& /*e*/) {
	cout << "This is asynchronous timer!" << endl;
}

void tuttimer2()
{
	boost::asio::io_service io;
	boost::asio::deadline_timer t(io, boost::posix_time::seconds(5));

	cout << "asynchronous timer start!" << endl;
	t.async_wait(&print); // 异步等待，传入回调函数，立即返回
	cout << "asynchronous timer processing!" << endl;

	io.run(); // 很重要！异步IO必须。如果不调用run()，
	          // 虽然操作被异步执行了，但没有一个等待它完成的机制，回调函数将得不到执行机会。
	cout << "asynchronous timer end!" << endl;
}

int main() {
	tuttimer2();
	return 0;
}

/*
运行结果：
asynchronous timer start!
asynchronous timer processing!
This is asynchronous timer!
asynchronous timer end!
*/

异步定时器使用bind

#include <iostream>
#include <boost/asio.hpp>
#include <boost/date_time/posix_time/posix_time.hpp>
#include <boost/bind.hpp>

void print1(const boost::system::error_code& /*e*/,
		boost::asio::deadline_timer* t, int* count)
{
	if (*count < 5)
	{
		cout << *count << "\n" << endl;
		++(*count);

		t->expires_at(t->expires_at() + boost::posix_time::seconds(1));

		t->async_wait(boost::bind(print1, boost::asio::placeholders::error, t, count));
	}

}

void tuttimer3()
{
	boost::asio::io_service io;
	int count = 0;
	boost::asio::deadline_timer t(io, boost::posix_time::seconds(1));

	t.async_wait(boost::bind(print1, boost::asio::placeholders::error, &t, &count));

	io.run();

	cout << "Final count is " << count << "\n" << endl;
}

int main() {
	tuttimer3();
	return 0;
}
/*
运行结果：
0

1

2

3

4

Final count is 5
*/