libjellyfish-2.0-dev 2.1.4-1 / usr / include / jellyfish / token_ring.hpp

/*  This file is part of Jellyfish.

    Jellyfish is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    Jellyfish is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with Jellyfish.  If not, see <http://www.gnu.org/licenses/>.
*/

#ifndef __JELLYFISH_TOKEN_RING_HPP__
#define __JELLYFISH_TOKEN_RING_HPP__

#include <vector>
#include <jellyfish/locks_pthread.hpp>

namespace jellyfish {
template<class cond_t = locks::pthread::cond>
class token_ring {
public:
  class token {
    bool   val;
    cond_t cond;
    token* next;
    friend class token_ring;

  public:
    void wait() {
      cond.lock();
      while(!val) { cond.wait(); }
      cond.unlock();
    }

    void pass() {
      next->cond.lock();
      val       = false;
      next->val = true;
      next->cond.signal();
      next->cond.unlock();
    }
  };

protected:
  typedef std::vector<token>            token_list;
  typedef typename token_list::iterator token_iterator;
  token_list tokens;

  void initialize() {
    if(tokens.size() == 0)
      return;

    tokens.front().val = true;
    tokens.back().next = &tokens.front();

    for(size_t i = 1; i < tokens.size(); ++i) {
      tokens[i].val    = false;
      tokens[i-1].next = &tokens[i];
    }
  }

public:
  token_ring(int nb_tokens) :
    tokens(nb_tokens)
  { initialize(); }

  ~token_ring() { }

  token& operator[](int i) { return tokens[i]; }

  void reset() {
    if(tokens.size() == 0)
      return;

    token_iterator it = tokens.begin();
    it->val = true;
    for(++it; it != tokens.end(); ++it)
      it->val = false;
  }
};
} // namespace jellyfish {
#endif