boost asio容易误用的一个地方

水木社区手机版

主题:boost asio容易误用的一个地方
楼主|z16166|2023-03-19 21:20:50|只看此ID
错误写法

class CMyClass
{
public:
         CMyClass() :
                 m_timer(m_io_context),
        {
        }

private:
        boost::asio::io_context m_io_context;
        boost::asio::deadline_timer m_timer;
};
--
FROM 221.218.163.*
1楼|weiwallz|2023-03-20 08:25:57|只看此ID
咦？错在哪里？

【在 z16166 的大作中提到: 】
: 错误写法
: class CMyClass
: {
: ...................
--
FROM 123.168.94.*
2楼|z16166|2023-03-20 11:41:18|只看此ID
成员按声明顺序初始化的，但我遇到m_timer初始化时m_io_context还是空的情况

【在 weiwallz 的大作中提到: 】
: 咦？错在哪里？
:
--
修改:z16166 FROM 221.218.163.*
FROM 221.218.163.*
3楼|weiwallz|2023-03-20 12:26:23|只看此ID
按理说不应该啊，m_io_context声明在先，所以到了m_timer的时候，m_io_context应该已经初始化了啊

【在 z16166 的大作中提到: 】
: 成员按声明顺序初始化的，但我遇到m_timer初始化时m_io_context还是空的情况
:
--
FROM 123.168.94.*
4楼|z16166|2023-03-20 16:53:02|只看此ID
确实很奇怪

我这边最开始没问题。
因为查一个问题，然后我把boost 1.81重新编译了一次，就出现了在m_timer的构造函数里面引用boost::asio::detail::scheduler::init_task()时遇到空指针的情况。

正好还保留了当时的一个栈

Thread 1 "my_agent" received signal SIGSEGV, Segmentation fault.
0x0000000000000000 in ?? ()
(gdb) bt
#0  0x0000000000000000 in ?? ()
#1  0x00000000004eccac in boost::asio::detail::scheduler::init_task (this=0xfffff7e36940) at /home/parallels/work/my_linux_agent/my_libs/out_arm64/boost/include/boost/asio/detail/impl/scheduler.ipp:188
#2  0x00000000004eb2e8 in boost::asio::detail::epoll_reactor::init_task (this=0xfffff7fcbdc0)
    at /home/parallels/work/my_linux_agent/my_libs/out_arm64/boost/include/boost/asio/detail/impl/epoll_reactor.ipp:149
#3  0x00000000004f95a8 in boost::asio::detail::deadline_timer_service<boost::asio::time_traits<boost::posix_time::ptime> >::deadline_timer_service (this=0xfffff7e35af0, context=...)
    at /home/parallels/work/my_linux_agent/my_libs/out_arm64/boost/include/boost/asio/detail/deadline_timer_service.hpp:74
#4  0x00000000004f8584 in boost::asio::detail::service_registry::create<boost::asio::detail::deadline_timer_service<boost::asio::time_traits<boost::posix_time::ptime> >, boost::asio::io_context> (
    owner=0xfffff7fe5e18) at /home/parallels/work/my_linux_agent/my_libs/out_arm64/boost/include/boost/asio/detail/impl/service_registry.hpp:87
#5  0x00000000004e9748 in boost::asio::detail::service_registry::do_use_service (this=0xfffff7fc7200, key=...,
    factory=0x4f8550 <boost::asio::detail::service_registry::create<boost::asio::detail::deadline_timer_service<boost::asio::time_traits<boost::posix_time::ptime> >, boost::asio::io_context>(void*)>,
    owner=0xfffff7fe5e18) at /home/parallels/work/my_linux_agent/my_libs/out_arm64/boost/include/boost/asio/detail/impl/service_registry.ipp:132
#6  0x0000000000759644 in boost::asio::detail::service_registry::use_service<boost::asio::detail::deadline_timer_service<boost::asio::time_traits<boost::posix_time::ptime> > > (owner=..., this=<optimized out>)
    at ../../../../out_arm64/boost/include/boost/asio/detail/impl/service_registry.hpp:76
#7  boost::asio::use_service<boost::asio::detail::deadline_timer_service<boost::asio::time_traits<boost::posix_time::ptime> > > (ioc=...) at ../../../../out_arm64/boost/include/boost/asio/impl/io_context.hpp:42
#8  boost::asio::detail::io_object_impl<boost::asio::detail::deadline_timer_service<boost::asio::time_traits<boost::posix_time::ptime> >, boost::asio::execution::any_executor<boost::asio::execution::context_as_t<boot::asio::execution_context&>, boost::asio::execution::detail::blocking::never_t<0>, boost::asio::execution::prefer_only<boost::asio::execution::detail::blocking::possibly_t<0> >, boost::asio::execution::prefer_only<oost::asio::execution::detail::outstanding_work::tracked_t<0> >, boost::asio::execution::prefer_only<boost::asio::execution::detail::outstanding_work::untracked_t<0> >, boost::asio::execution::prefer_only<boost::asi::execution::detail::relationship::fork_t<0> >, boost::asio::execution::prefer_only<boost::asio::execution::detail::relationship::continuation_t<0> > > >::io_object_impl<boost::asio::io_context> (context=...,
    this=0xfffff7fe5e78) at ../../../../out_arm64/boost/include/boost/asio/detail/io_object_impl.hpp:60
#9  boost::asio::basic_deadline_timer<boost::posix_time::ptime, boost::asio::time_traits<boost::posix_time::ptime>, boost::asio::execution::any_executor<boost::asio::execution::context_as_t<boost::asio::execution_cotext&>, boost::asio::execution::detail::blocking::never_t<0>, boost::asio::execution::prefer_only<boost::asio::execution::detail::blocking::possibly_t<0> >, boost::asio::execution::prefer_only<boost::asio::execution:detail::outstanding_work::tracked_t<0> >, boost::asio::execution::prefer_only<boost::asio::execution::detail::outstanding_work::untracked_t<0> >, boost::asio::execution::prefer_only<boost::asio::execution::detail::elationship::fork_t<0> >, boost::asio::execution::prefer_only<boost::asio::execution::detail::relationship::continuation_t<0> > > >::basic_deadline_timer<boost::asio::io_context> (context=...,
    this=0xfffff7fe5e78) at ../../../../out_arm64/boost/include/boost/asio/basic_deadline_timer.hpp:182
#10 NFProxy::NFProxy (this=0xfffff7fe5dd0, pEventHandler=0x1a9ef80 <g_proxy>) at ./nfproxy.h:1179
#11 0x00000000007516c4 in startProxy (pHandler=0x1a9ef80 <g_proxy>) at ./nfproxy.cpp:41
#12 nfapi::nf_init (driverName=<optimized out>, pHandler=0x1a9ef80 <g_proxy>) at ./nfproxy.cpp:83
#13 0x00000000004cd2fc in CNetFilter::StartInternal (this=0x1593f38 <CNetFilter::GetInstance()::filter>) at /home/parallels/work/my_linux_agent/daemon/netfilter/CNetFilter.cpp:181
#14 0x00000000004cce90 in CNetFilter::Start (this=0x1593f38 <CNetFilter::GetInstance()::filter>) at /home/parallels/work/my_linux_agent/daemon/netfilter/CNetFilter.cpp:129
#15 0x0000000000413b14 in CmyAgent::EnableSubModules (this=0x1a94ea8 <CmyAgent::GetInstance()::instance>) at /home/parallels/work/my_linux_agent/daemon/agent.cpp:583
#16 0x00000000004135d4 in CmyAgent::EnableAgent (this=0x1a94ea8 <CmyAgent::GetInstance()::instance>) at /home/parallels/work/my_linux_agent/daemon/agent.cpp:508
#17 0x0000000000410a78 in CmyAgent::WorkLoop (this=0x1a94ea8 <CmyAgent::GetInstance()::instance>) at /home/parallels/work/my_linux_agent/daemon/agent.cpp:115
#18 0x00000000004b4dcc in app_running () at /home/parallels/work/my_linux_agent/daemon/main.cpp:16
#19 0x00000000004b4fd0 in main (argc=1, args=0xfffffffff628) at /home/parallels/work/my_linux_agent/daemon/main.cpp:50
(gdb)

【在 weiwallz 的大作中提到: 】
: 按理说不应该啊，m_io_context声明在先，所以到了m_timer的时候，m_io_context应该已经初始化了啊
:
--
修改:z16166 FROM 221.218.163.*
FROM 221.218.163.*
5楼|ziqin|2023-03-20 18:09:28|只看此ID
boost::asio::io_context m_io_context = {};

【在 z16166 的大作中提到: 】
: 错误写法
: class CMyClass
: {
: ...................
--
FROM 115.193.172.*
6楼|mango7788|2023-03-20 20:32:45|只看此ID
加一个 m_io_context() 呢？
【在 z16166 的大作中提到: 】
: 错误写法
: class CMyClass
: {
: ...................
--
FROM 167.220.233.*
7楼|z16166|2023-03-20 20:52:06|只看此ID
我现在用的是unique_ptr。等折腾完手头的另一个问题，换回去试试。

这个问题更诡异点，在join boost asio的worker线程时会崩，worker线程设为1个也会。目前看起来是个编译环境问题（arm64上musl + gcc + boost），也影响到了m_timer的初始化。

跟这个report几乎一样：
https://marc.info/?l=boost-bugs&m=137997373100783&w=2
试了把boost::thread换为std::thread就没这个崩溃问题了

class CMyClass
{
public:
         CMyClass()
         {
                    m_io_context = std::make_unique<boost::asio::io_context>();
                    m_timer = std::make_unique<boost::asio::deadline_timer>(*m_io_context);
        }

       ~CMyClass() {
                m_timer->reset();
                m_io_context->reset();
       }

private:
        std::unique_ptr<boost::asio::io_context> m_io_context;
        std::unique_ptr<boost::asio::deadline_timer> m_timer;
};

【在 ziqin 的大作中提到: 】
: boost::asio::io_context m_io_context = {};
:

【在 mango7788 的大作中提到: 】
: 加一个 m_io_context() 呢？
--
修改:z16166 FROM 221.218.163.*
FROM 221.218.163.*
8楼|ziqin|2023-03-20 23:16:20|只看此ID
能用std尽量用std，boost里一堆HAS_STD_XXX的宏都用起来

【在 z16166 的大作中提到: 】
: 我现在用的是unique_ptr。等折腾完手头的另一个问题，换回去试试。
: 这个问题更诡异点，在join boost asio的worker线程时会崩，worker线程设为1个也会。目前看起来是个编译环境问题（arm64上musl + gcc + boost），也影响到了m_timer的初始化。
: 跟这个report几乎一样：
: ...................
--
FROM 115.193.172.*
9楼|z16166|2023-03-21 09:56:56|只看此ID
别人的库里的一个代码，还好有源码。
这个代码也踩了boost asio的坑，比如在worker线程之外的stop线程里直接关闭socket，asio不允许这么搞，要走strand或者post到worker线程里去关闭socket。还是得好好看文档和例子。

【在 ziqin 的大作中提到: 】
: 能用std尽量用std，boost里一堆HAS_STD_XXX的宏都用起来
:
--
FROM 221.218.163.*