使用pthreads优雅地退出主线程

我目前正在上一门课，学习线程同步。任务要求我们首先实现一个基于pthreads的简单线程库。他们向我们提供了以下头文件，并告诉我们不应该以任何方式修改它：

#include <pthread.h>
#include <cstring>

class Task {
protected:
    /* -- NAME */
    static const int MAX_NAME_LEN = 15;
    char name[MAX_NAME_LEN];
    /* -- IMPLEMENTATION */
    pthread_t thread_id;
    /* If you implement tasks using pthread, you may need to store
    the thread_id of the thread associated with this task.
    */
public:
    /* -- CONSTRUCTOR/DESTRUCTOR */
    Task(const char _name[]) {
    /* Create, initialize the new task. The task is started
    with a separate invocation of the Start() method. */
    std::strncpy(name, _name, MAX_NAME_LEN);
    }
    ~Task();
    /* -- ACCESSORS */
    char * Name();
    /* Return the name of the task. */
    /* -- TASK LAUNCH */
    virtual void Start();
    /* This method is used to start the thread. For basic tasks
    implemented using pthreads, this is where the thread is
    created and started. For schedulable tasks (derived from
    class Task) this is where the thread is created and handed
    over to the scheduler for execution. The functionality of
    the task is defined in "Run()"; see below. This method is
    called in the constructor of Task.
    */
    /* -- TASK FUNCTIONALITY */
    //make a thread here
    virtual void Run() = 0;
    /* The method that is executed when the task object is
    started. When the method returns, the thread can be
    terminated. The method returns 0 if no error. */
    /* -- MAIN THREAD TERMINATION */
    static void GracefullyExitMainThread();
    /* This function is called at the end of the main() function.
    Depending on the particular thread implementation, we have
    to make sure that the main thread (i.e., the thread that
    runs executes the main function) either waits until all
    other threads are done or exits in a way that does not
    terminate them.
    */
};

我的问题是关于GracefullyExitMainThread()函数的。有人告诉我，我需要在它的实现中使用pthread_join()，但当它是一个类方法时，我不知道如何将线程id传递给它。此外，我本以为它们会在头中包含某种数组或其他结构，以跟踪创建的所有线程。

如果我的帖子很难理解或阅读，很抱歉。我仍在学习C++的所有细微差别，这是我在stackoverflow上的第一篇文章。非常感谢您的帮助。