boost基础环境搭建

因为现在手上的老的基类库经常出现丢包，以及从ServiceAClient 发送消息到 ServiceBServer时出现消息失败的情况，以及现有的莫名其妙的内存泄露的问题，以及目前还是c++0x，准确地说，是c with class的写法，而且支持windows server。

所以，现在想拥抱c++11，并解决上述问题。

选择Boost.Asio，一样是随便找了个库，有网友说库写的不错，就拿来用了，内部原理没看，只知道跨平台，支持c++11.

1.下载boost软件包
https://www.boost.org/users/download/

到下载地址里下载了1.68.0

然后放到某目录下，tar -zxvf boost1.68.0.tar.gz

2.安装前配置
现有环境，centos 64bit 6.10
进入boost目录后，运行./bootstrap.sh

3.编译
执行bootstrap.sh后，会在当前目录下生成b2文件
在这里执行： ./b2进行编译

4.安装
sudo ./b2 install

不加sudo会报权限错误等问题。

5.测试
编写代码

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

int main()
{
    boost::asio::io_service io;
    boost::asio::deadline_timer t(io, boost::posix_time::seconds(5));
    t.wait();
    std::cout << "Hello, world!" << std::endl;

    return 0;
}

代码解释：
Timer.1 - Using a timer synchronously
Source listing for Timer.1
This tutorial program introduces asio by showing how to perform a blocking wait on a timer.

We start by including the necessary header files.

All of the asio classes can be used by simply including the "asio.hpp" header file.

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

Since this example uses timers, we need to include the appropriate Boost.Date_Time header file for manipulating times.

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

All programs that use asio need to have at least one io_service object. This class provides access to I/O functionality. We declare an object of this type first thing in the main function.

int main()
{
  boost::asio::io_service io;

Next we declare an object of type boost::asio::deadline_timer. 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. The second argument to the constructor sets the timer to expire 5 seconds from now.

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

In this simple example we perform a blocking wait on the timer. That is, the call to deadline_timer::wait() will not return until the timer has expired, 5 seconds after it was created (i.e. not from when the wait starts).

A deadline timer is always in one of two states: "expired" or "not expired". If the deadline_timer::wait() function is called on an expired timer, it will return immediately.

  t.wait();

Finally we print the obligatory "Hello, world!" message to show when the timer has expired.

  std::cout << "Hello, world!" << std::endl;

  return 0;
}

编译运行：
g++ -Wall -std=c++14 test_xiaoliuzi.cpp -o xtest_xiaoliuzi -lboost_system -lboost_date_time

需要链接动态链接库：
如果不链接动态链接库，编译会报错：
/tmp/ccRacuCr.o: In function boost::system::system_category()': test_xiaoliuzi.cpp:(.text._ZN5boost6system15system_categoryEv[_ZN5boost6system15system_categoryEv]+0x1): undefined reference to boost::system::detail::system_category_instance'
/tmp/ccRacuCr.o: In function boost::system::generic_category()': test_xiaoliuzi.cpp:(.text._ZN5boost6system16generic_categoryEv[_ZN5boost6system16generic_categoryEv]+0x1): undefined reference to boost::system::detail::generic_category_instance'
/tmp/ccRacuCr.o: In function boost::asio::detail::posix_event::posix_event()': test_xiaoliuzi.cpp:(.text._ZN5boost4asio6detail11posix_eventC2Ev[_ZN5boost4asio6detail11posix_eventC5Ev]+0x3e): undefined reference to pthread_condattr_setclock'
/tmp/ccRacuCr.o: In function boost::asio::detail::posix_thread::~posix_thread()': test_xiaoliuzi.cpp:(.text._ZN5boost4asio6detail12posix_threadD2Ev[_ZN5boost4asio6detail12posix_threadD5Ev]+0x26): undefined reference to pthread_detach'
/tmp/ccRacuCr.o: In function boost::asio::detail::posix_thread::join()': test_xiaoliuzi.cpp:(.text._ZN5boost4asio6detail12posix_thread4joinEv[_ZN5boost4asio6detail12posix_thread4joinEv]+0x2b): undefined reference to pthread_join'
/tmp/ccRacuCr.o: In function boost::asio::basic_deadline_timer<boost::posix_time::ptime, boost::asio::time_traits<boost::posix_time::ptime> >::basic_deadline_timer(boost::asio::io_context&, boost::posix_time::time_duration const&)': test_xiaoliuzi.cpp:(.text._ZN5boost4asio20basic_deadline_timerINS_10posix_time5ptimeENS0_11time_traitsIS3_EEEC2ERNS0_10io_contextERKNS2_13time_durationE[_ZN5boost4asio20basic_deadline_timerINS_10posix_time5ptimeENS0_11time_traitsIS3_EEEC5ERNS0_10io_contextERKNS2_13time_durationE]+0x33): undefined reference to boost::system::detail::system_category_instance'
/tmp/ccRacuCr.o: In function boost::asio::basic_deadline_timer<boost::posix_time::ptime, boost::asio::time_traits<boost::posix_time::ptime> >::wait()': test_xiaoliuzi.cpp:(.text._ZN5boost4asio20basic_deadline_timerINS_10posix_time5ptimeENS0_11time_traitsIS3_EEE4waitEv[_ZN5boost4asio20basic_deadline_timerINS_10posix_time5ptimeENS0_11time_traitsIS3_EEE4waitEv]+0x18): undefined reference to boost::system::detail::system_category_instance'
/tmp/ccRacuCr.o: In function boost::asio::detail::deadline_timer_service<boost::asio::time_traits<boost::posix_time::ptime> >::destroy(boost::asio::detail::deadline_timer_service<boost::asio::time_traits<boost::posix_time::ptime> >::implementation_type&)': test_xiaoliuzi.cpp:(.text._ZN5boost4asio6detail22deadline_timer_serviceINS0_11time_traitsINS_10posix_time5ptimeEEEE7destroyERNS7_19implementation_typeE[_ZN5boost4asio6detail22deadline_timer_serviceINS0_11time_traitsINS_10posix_time5ptimeEEEE7destroyERNS7_19implementation_typeE]+0x1b): undefined reference to boost::system::detail::system_category_instance'
collect2: error: ld returned 1 exit status

如果只链接-lboost_system， 没有链接-lboost_date_time，编译不会报错，但是运行会报错：

./xtest_xiaoliuzi: error while loading shared libraries: libboost_system.so.1.68.0: cannot open shared object file: No such file or directory

用到的辅助命令：
为了查看当前的开发机器上是否安装过其他版本的boost，需要用到：
[xiaoliuzi@ boost_1_68_0]$ sudo /sbin/ldconfig -p | grep boost_thread
libboost_thread.so.1.68.0 (libc6,x86-64) => /usr/local/lib/libboost_thread.so.1.68.0
libboost_thread.so (libc6,x86-64) => /usr/local/lib/libboost_thread.so
编译或者运行出错也有可能会是其他版本同时存在导致的。

Reference：
https://www.boost.org/users/download/
https://www.boost.org/doc/libs/1_68_0/more/getting_started/unix-variants.html#install-boost-build
https://www.boost.org/doc/libs/1_63_0/doc/html/boost_asio/tutorial.html
https://blog.csdn.net/big_bit/article/details/51321251