c++ 中的 boost 库链接问题

Question

实施基于时间的事件“验证”时出现问题，例如等待方法在 1 小时后获取当前时间和时间并休眠 1 小时，然后调用此验证 function。
但是当我运行这段代码时它显示错误
升压库版本是：1.71

在 main.cpp 中，我试图使两个触摸文件和时钟同步，然后实现 get_latest_clock_entry 打印时钟文件的最后修改时间。 然后等待 function 等待 1 小时并运行验证 function。等待 function 应该每小时调用一次验证方法。 主.cpp

#include <iostream>
#include <fstream>
#include <time.h>
#include <sys/stat.h>
#include <boost/date_time.hpp>
#include <boost/thread/thread.hpp> 
using namespace std;

constexpr char clock_file[] = "/home/saman/Desktop/clock";
constexpr char sync_file[] = "/home/saman/Desktop/synchronized";

class TimeEvent {
public:
     void receive_time_event(timespec& time) {
        // Create clock file
        ofstream clockFile(clock_file);
        if (!clockFile.is_open()) {
            cout << "Failed to open file" << endl;
        }
        clockFile.close();
        // Create synchronized file
        ofstream synchronizedFile(sync_file);
        if (!synchronizedFile.is_open()) {
            cout << "Failed to open file" << endl;
        }
        synchronizedFile.close();
    }

    timespec get_latest_clock_entry(){
    string clockFilePath = clock_file;
    struct stat fileStat;
    if(stat(clockFilePath.c_str(), &fileStat) == 0){
        time_t mtime = fileStat.st_mtime;
        timespec time;
        time.tv_sec = mtime;
        time.tv_nsec = 0;
        char timeString[50];
        strftime(timeString, sizeof(timeString), "%Y-%m-%d %H:%M:%S", gmtime(&time.tv_sec));
        cout << "Last modified time "<< clockFilePath << " : " << timeString << endl;
        return time;
    }
    else{
        cout << "Can't retrieve last modified time " << clockFilePath << endl;
        return {0,0};
    }
}
    void wait(){
        boost::posix_time::ptime timeLocal = boost::posix_time::second_clock::local_time();
        cout << "Now Time" << timeLocal << endl;
        boost::posix_time::ptime counter = timeLocal + boost::posix_time::hours(1);
        cout << "update Time" << timeLocal << endl;
        boost::this_thread::sleep(counter);
    }

    void validate(){
        cout << "hi" << endl;
    }
};

int main() {
    TimeEvent timeEvent;
    timespec time;
    timespec_get(&time, TIME_UTC);
    timeEvent.receive_time_event(time);
    auto lastModifiedTime = timeEvent.get_latest_clock_entry();
    while(1){
        timeEvent.wait();
        timeEvent.validate();
    }
    return 0;
}

错误：

/usr/bin/ld: /tmp/ccJEJpvk.o: in function `boost::condition_variable::condition_variable()':
2.cpp:(.text._ZN5boost18condition_variableC2Ev[_ZN5boost18condition_variableC5Ev]+0xc5): undefined reference to `pthread_condattr_setclock'
/usr/bin/ld: /tmp/ccJEJpvk.o: in function `boost::detail::interruption_checker::interruption_checker(pthread_mutex_t*, pthread_cond_t*)':
2.cpp:(.text._ZN5boost6detail20interruption_checkerC2EP15pthread_mutex_tP14pthread_cond_t[_ZN5boost6detail20interruption_checkerC5EP15pthread_mutex_tP14pthread_cond_t]+0x29): undefined reference to `boost::detail::get_current_thread_data()'
/usr/bin/ld: /tmp/ccJEJpvk.o: in function `boost::condition_variable::do_wait_until(boost::unique_lock<boost::mutex>&, boost::detail::mono_platform_timepoint const&)':
2.cpp:(.text._ZN5boost18condition_variable13do_wait_untilERNS_11unique_lockINS_5mutexEEERKNS_6detail23mono_platform_timepointE[_ZN5boost18condition_variable13do_wait_untilERNS_11unique_lockINS_5mutexEEERKNS_6detail23mono_platform_timepointE]+0x135): undefined reference to `boost::this_thread::interruption_point()'
collect2: error: ld returned 1 exit status

更新：
用 g++ -o main main.cpp -lpthread 编译后

/usr/bin/ld: /tmp/cccOLyt1.o: in function `boost::detail::interruption_checker::interruption_checker(pthread_mutex_t*, pthread_cond_t*)':
2.cpp:(.text._ZN5boost6detail20interruption_checkerC2EP15pthread_mutex_tP14pthread_cond_t[_ZN5boost6detail20interruption_checkerC5EP15pthread_mutex_tP14pthread_cond_t]+0x29): undefined reference to `boost::detail::get_current_thread_data()'
/usr/bin/ld: /tmp/cccOLyt1.o: in function `boost::condition_variable::do_wait_until(boost::unique_lock<boost::mutex>&, boost::detail::mono_platform_timepoint const&)':
2.cpp:(.text._ZN5boost18condition_variable13do_wait_untilERNS_11unique_lockINS_5mutexEEERKNS_6detail23mono_platform_timepointE[_ZN5boost18condition_variable13do_wait_untilERNS_11unique_lockINS_5mutexEEERKNS_6detail23mono_platform_timepointE]+0x135): undefined reference to `boost::this_thread::interruption_point()'
collect2: error: ld returned 1 exit status

Answer 1

您需要同时链接boost_thread和pthread 。

$ g++ boost.cpp -o boost -lboost_thread -lpthread

$ ldd ./boost
    linux-vdso.so.1 (0x00007ffc1bd79000)
    libboost_thread.so.1.71.0 => /lib/x86_64-linux-gnu/libboost_thread.so.1.71.0 (0x00007fc4b7a51000)
    libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007fc4b7a2e000)
    libstdc++.so.6 => /lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007fc4b784c000)
    libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007fc4b7831000)
    libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007fc4b763f000)
    /lib64/ld-linux-x86-64.so.2 (0x00007fc4b7aee000)
    libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007fc4b74f0000)

$ ./boost 
Failed to open file
Failed to open file
Can't retrieve last modified time /home/saman/Desktop/clock
Now Time2023-Jan-19 03:43:47
update Time2023-Jan-19 03:43:47
hi

仅供参考，首先您必须找到缺少的内容，在本例中为boost::detail::get_current_thread_data 。

使用下面的行

$ find /usr/lib -name 'libboost*' | xargs -i /bin/bash -x -c "nm -C {}" | grep boost::detail::get_current_thread_data

然后在地址后查找状态为“T”的行。 它上面的库是您需要包含的库。

+ nm -C /usr/lib/x86_64-linux-gnu/libboost_thread.a
0000000000000210 T boost::detail::get_current_thread_data()

Answer 2

您需要与 Boost.Thread 库链接。 例如，如果您使用 clang 或 gcc，请将-lboost_thread添加到您的编译器命令行。