C++虛函數和線程

這裏是我的main.cpp代碼：C++虛函數和線程

#include <opencv2/opencv.hpp> 
using std::string; 

#include "caffe_thread_learn.hpp" 

class VideoCaptureTest : public InternalThread { 
public: 
    string video; 
    explicit VideoCaptureTest(string v) : video(v) { StartInternalThread(); } 
protected: 
    virtual void InternalThreadEntry(); 
}; 

void VideoCaptureTest::InternalThreadEntry(){ 
    std::cout << "video child" << std::endl; 
} 

int main(){ 

    InternalThread* vt = new VideoCaptureTest("/Users/zj-db0655/Documents/data/528100078_5768b1b1764438418.mp4"); 
    delete vt; 

    return 0; 
}

caffe_thread.cpp代碼：

#include "caffe_thread_learn.hpp" 


InternalThread::~InternalThread() { 
    StopInternalThread(); 
} 

bool InternalThread::is_started() const { 
    return thread_ && thread_->joinable(); 
} 

bool InternalThread::must_stop() { 
    return thread_ && thread_->interruption_requested(); 
} 

void InternalThread::StopInternalThread() { 
    if (is_started()) { 
     thread_->interrupt(); 
     try { 
      thread_->join(); 
     } catch (boost::thread_interrupted&) { 
     } catch (std::exception& e) { 
      std::cout << "Thread exception: " << e.what(); 
     } 
    } 
} 


void InternalThread::StartInternalThread() { 
    thread_.reset(new boost::thread(&InternalThread::entry, this)); 
} 

void InternalThread::entry() { 
    InternalThreadEntry(); 
}

caffe_thread.hpp代碼

#ifndef caffe_thread_learn_hpp 
#define caffe_thread_learn_hpp 

#include <stdio.h> 

#include <boost/thread.hpp> 
#include <boost/shared_ptr.hpp> 

namespace boost { class thread; } 

class InternalThread { 
public: 
    InternalThread() : thread_() {} 
    virtual ~InternalThread(); 

    /** 
    * Caffe's thread local state will be initialized using the current 
    * thread values, e.g. device id, solver index etc. The random seed 
    * is initialized using caffe_rng_rand. 
    */ 
    void StartInternalThread(); 

    /** Will not return until the internal thread has exited. */ 
    void StopInternalThread(); 

    bool is_started() const; 

protected: 
    /* Implement this method in your subclass 
    with the code you want your thread to run. */ 
    virtual void InternalThreadEntry() { std::cout << "parent" << std::endl; } 
    virtual void fun() {} 

    /* Should be tested when running loops to exit when requested. */ 
    bool must_stop(); 

private: 
    void entry(); 

    boost::shared_ptr<boost::thread> thread_; 
}; 

#endif /* caffe_thread_learn_hpp */

實際上，輸出是：parant

但是，我想輸出應該是：視頻孩子。因爲當調用VideoCaptureTest中的StartInternalThread時，它會新建一個帶參數（& InternalThread :: entry，this）的線程，並且我認爲這個指向VideoCaptureTest的指針並將調用VideoCaptureTest的InternalThreadEntry輸出視頻子節點。但是，它輸出父項。

謝謝！

來源

2016-09-11 ScutterKey

解決此類問題的正確工具是您的調試器。在*堆棧溢出問題之前，您應該逐行執行您的代碼。如需更多幫助，請閱讀[如何調試小程序（由Eric Lippert撰寫）]（https://ericlippert.com/2014/03/05/how-to-debug-small-programs/）。至少，您應該\編輯您的問題，以包含一個[最小，完整和可驗證]（http://stackoverflow.com/help/mcve）示例，該示例再現了您的問題，以及您在調試器。 –

這可能是您的線程之間的時間問題。您創建一個新的VideoCaptureTest對象，然後在StartInternalThread創建的線程有機會運行之前立即將其刪除。調用析構函數時，在生成輸出之前，對象將被拆除爲InternalThread對象。

要麼在你的new/delete之間放一段睡眠，要麼等待線程在破壞之前完成。

來源

2016-09-11 02:19:06 1201ProgramAlarm

非常感謝！有用！ – ScutterKey

C++虛函數和線程

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