Re: Question on C++ Thread Class and inheritance/polymorphism with POSIX pthread

From:
"Chris M. Thomasson" <no@spam.invalid>
Newsgroups:
comp.lang.c++
Date:
Tue, 28 Oct 2008 16:07:05 -0700
Message-ID:
<ge85fk$v9g$1@aioe.org>
FWIW, here is a quick example (in the form of a fully compliable program
with error checking omitted) of how I use POSIX threads within a C++
environment:
_________________________________________________________________
/* Simple Thread Object
______________________________________________________________*/
#include <pthread.h>

extern "C" void* thread_entry(void*);

class thread_base {
  pthread_t m_tid;
  friend void* thread_entry(void*);
  virtual void on_thread_entry() = 0;

public:
  virtual ~thread_base() = 0;

  void thread_run() {
    pthread_create(&m_tid, NULL, thread_entry, this);
  }

  void thread_join() {
    pthread_join(m_tid, NULL);
  }
};

thread_base::~thread_base() {}

void* thread_entry(void* state) {
  reinterpret_cast<thread_base*>(state)->on_thread_entry();
  return 0;
}

template<typename T>
struct thread : public T {
  thread() : T() {
    this->thread_run();
  }

  ~thread() {
    this->thread_join();
  }

  template<typename T_p1>
  thread(T_p1 p1) : T(p1) {
    this->thread_run();
  }

  template<typename T_p1, typename T_p2>
  thread(T_p1 p1, T_p2 p2) : T(p1, p2) {
    this->thread_run();
  }

  // [and on and on for for params...]
};

/* Simple Usage Example
______________________________________________________________*/
#include <string>
#include <cstdio>

class worker : public thread_base {
  std::string const m_name;

  void on_thread_entry() {
    std::printf("(%p)->worker(%s)::on_thread_entry()\n",
      (void*)this, m_name.c_str());
  }

public:
  worker(std::string const& name)
    : m_name(name) {
    std::printf("(%p)->worker(%s)::my_thread()\n",
      (void*)this, m_name.c_str());
  }

  ~worker() {
    std::printf("(%p)->worker(%s)::~my_thread()\n",
     (void*)this, m_name.c_str());
  }
};

int main(void) {
  {
    thread<worker> workers[] = {
      "Chris",
      "John",
      "Jane",
      "Steve",
      "Richard",
      "Lisa"
    };

    worker another_worker("Jeff");
    another_worker.thread_run();
    another_worker.thread_join();
  }

  std::puts("\n\n\n__________________\nhit <ENTER> to exit...");
  std::fflush(stdout);
  std::getchar();
  return 0;
}
_________________________________________________________________

IMVHO, this is very straight forward and works well. In fact, I think I like
it better than the Boost method... Humm... Well, what do you all think about
the design? Is it crap?

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