//boost :boost_1_44
//http://www.boost.org/
//IDE :Microsoft Visual Studio 2008
// Version 9.0.30729.1 SP
// Microsoft .NET Framework
// Version 3.5 SP1
// Installed Edition: Enterprise
// Microsoft Visual Basic 2008
// Microsoft Visual C++ 2008
// Microsoft Visual Studio 2008 Team Explorer
//OS :
//OS 名称: Microsoft Windows XP Professional
//OS 版本: 5.1.2600 Service Pack 3 Build 2600
//OS 制造商: Microsoft Corporation
//OS 配置: 成员工作站
//OS 构件类型: Multiprocessor Free
//系统制造商: Dell Inc.
//系统型号: Precision WorkStation 690
//系统类型: X86-based PC
//处理器: 安装了 2 个处理器。
//date: 2012-12-19-->21
//CONTENT
//Basic Skills
//内容引用URL :http://think-async.com/Asio/boost_asio_1_5_3/doc/html/boost_asio/tutorial.html
//Using a timer synchronously
#include "iostream"
#include "boost/asio.hpp"
#include "boost/date_time/posix_time/posix_time.hpp"
void class1_Timer()
{
//1. all programs that use asio need to have
// at least one io_service object.
//2. this class provides access to I/O functionality
//3. declare an object of this type first thing in the main function
boost::asio::io_service io;
//4. declare an object of type boost::asio::deadline_timer
//5. the core asio classes that provide I/O functionality
// (or as in this case timer functionality)always take a
// reference to an io_service as their first constructor argument
//6. the second argument to the constructor set the timer to expire
// 5 seconds from now.
boost::asio::deadline_timer t(io,boost::posix_time::seconds(5));
//7. the call to deadline_timer::wait() will
// not return until the timer has expired.
// 5 seconds after it was created.
SYSTEMTIME sysTimer;
GetSystemTime(&sysTimer);
std::cout<<sysTimer.wSecond<<std::endl;
t.wait();//此时开始计时
GetSystemTime(&sysTimer);
std::cout<<sysTimer.wSecond<<std::endl;
//差值是5..
}
//---------------------------------------------------------------------------->
//Using a timer asynchronously
//the same head files with class1_Timer()
void class2_Timer()
{
//1. using asio's asynchronous functionality means
// having a callback function that will be called
// when an asynchronous operation completes
boost::asio::io_service io;
boost::asio::deadline_timer t(io,boost::posix_time::seconds(5));
//Main Thread,Thread ID 0x000007a0
//设置回调.
extern void print(const boost::system::error_code &);
t.async_wait(print);//此时开始异步计时.
io.run();//会等待计时器过期
//1. io.run()后,这个函数一直运行,此例中io.run()的工作是异步等待定时器t过期.
// 当定时器t过期后,io.run()调用设置的回调
//2. 如果不设置回调,io_service::run()会立即返回.
std::cout <<"Hello,word--Class2_async_Timer!\n";
}
void print(const boost::system::error_code &)
{
//Main Thread,Thread ID 0x000007a0
std::cout <<"Hello,word!\n";
}
//---------------------------------------------------------------------------->
//Binding arguments to a handler
#include "boost/bind.hpp"
void class3_Timer()
{
boost::asio::io_service io;
int count = 0;
boost::asio::deadline_timer t(io,boost::posix_time::seconds(1));
extern void print(const boost::system::error_code&/*e*/,
boost::asio::deadline_timer *t,int*count);
t.async_wait(boost::bind(print,boost::asio::placeholders::error,&t,&count));//定时器t开始计时
io.run();//异步等待t过期,并调用回调print,
//print重复异步等待计时器,
std::cout<<"Final count is" << count <<"\n";
return ;
}
void print(const boost::system::error_code&/*e*/,
boost::asio::deadline_timer *t,
int*count)
{
if(*count <5)
{
std::cout << *count <<"\n";
++(*count);
// move the expiry time for the timer along by one second from the previous expiry time
//此处的expires_at是根据第一个async_wait开始计算
// 即:在下面的async_wait前断点停止此线程(main thread),计时器线程仍在计时
// main thread停止足够时间,再调用async_wait会立即返回
// async_wait要等待的时间都已经过期.
t->expires_at(t->expires_at() + boost::posix_time::seconds(5));
t->async_wait(boost::bind(print,boost::asio::placeholders::error,t,count));
//注意此处不是递归调用..
//只是在函数中将print设置给io作为回调函数,并传递不同的参数...
//t->async_wait检测的时间过期即返回.退出print,io取调用新的回调(仍是print)
}
}
//---------------------------------------------------------------------------->
//using a member function as a handler
class printer{
public:
printer(boost::asio::io_service &io)
:timer_(io,boost::posix_time::seconds(5))
,count_(0)
{
//所有的noe-static成员函数都有this参数,需要提供给boost::bind
timer_.async_wait(boost::bind(&printer::print,this));
}
~printer(){
std::cout << "final count is " <<count_ <<"\n";
}
void print()
{
if(count_ < 5)
{
std::cout << count_ <<"\n";
++count_;
timer_.expires_at(timer_.expires_at() + boost::posix_time::seconds(5));
timer_.async_wait(boost::bind(&printer::print,this));
}
}
private:
boost::asio::deadline_timer timer_;
int count_;
};
void class4_Timer(){
boost::asio::io_service io;
printer prt(io);
io.run();
}
//---------------------------------------------------------------------------->
//demonstrates the use of the boost::asio::strand class
//to synchronise callback handlers in a multithreaded program
//前4个例子都是通过同一个线程调用io.run(),没有handler的同步问题
//回调是被调用io.run()的线程调用.
//单线程缺陷
// 长任务执行期间无法获得回应.
// 多处理设备无法提升性能
//多线程:当handler处理非线程安全的资源时,需要同步
#include "boost/thread/thread.hpp"
class printerMul{
public:
printerMul(boost::asio::io_service &io)
:strand_(io),
timer1_(io,boost::posix_time::seconds(5)),
timer2_(io,boost::posix_time::seconds(5)),
count_(0){
//被同一个boost::asio::strand warp的handler 将无法并行运行..
//一个handler将在另handler开始前完成.
//没有被boost::asio::strand dispatch或者被不同的boost::asio::strand dispatch的handler将仍会并行执行
timer1_.async_wait(strand_.wrap(boost::bind(&printerMul::print1,this)));
timer2_.async_wait(strand_.wrap(boost::bind(&printerMul::print2,this)));
}
~printerMul(){
std::cout << "Fianl count is " <<count_ <<"\n";
}
void print1()
{
if(count_ <10)
{
std::cout<<GetCurrentThreadId() <<" ";
std::cout<<"Timer1:"<<count_<<"\n";
++count_;
timer1_.expires_at(timer1_.expires_at() \
+ boost::posix_time::seconds(2));
timer1_.async_wait(strand_.wrap(boost::bind(&printerMul::print1,this)));
}
}
void print2()
{
if(count_ < 10)
{
std::cout<<GetCurrentThreadId() <<" ";
std::cout <<"Timer2:"<<count_<<"\n";
++count_;
timer2_.expires_at(timer2_.expires_at()\
+boost::posix_time::seconds(4));
timer2_.async_wait(strand_.wrap(boost::bind(&printerMul::print2,this)));
}
}
private:
boost::asio::strand strand_;
boost::asio::deadline_timer timer1_;
boost::asio::deadline_timer timer2_;
int count_;
};
void class5_Timer(){
boost::asio::io_service io;
printerMul prt(io);
//io.run()被两个线程调用..
//1.被boost::thread t 线程调用
boost::thread t(boost::bind(&boost::asio::io_service::run,&io));
//2.被主线程调用
io.run();//(疑问:貌似执行过主线程的io.run()才激活boost::thread t的io.run()?)
//print1 与print2两个函数不会同时执行,也不固定谁在哪个线程执行..
t.join();
//Main Thread ID:0x00000bd0 (3024
//共3个线程
//3024 main
//1560 boost::thread created
//3rd 应该是计时线程..
//cout<<
//1560 Timer2:0
//3024 Timer1:1
//1560 Timer1:2
//3024 Timer1:3
//1560 Timer2:4
//3024 Timer1:5
//1560 Timer1:6
//3024 Timer2:7
//3024 Timer1:8
//3024 Timer1:9
//Fianl count is 10
}
int main()
{
int a = 1;
while(0 != a)
{
std::cout << "input your choice"<<std::endl;
std::cin >> a;
switch(a)
{
case 1:class1_Timer();
break;
case 2:class2_Timer();
break;
case 3:class3_Timer();
break;
case 4:class4_Timer();
break;
case 5:class5_Timer();
break;
case 6:
{
extern void class6();
class6();
}
break;
default:break;
}
}
return 0;
}
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