sem.h

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/*  Copyright (C) 2013  Eric Larson and Rochelle Palting
    elarson@seattleu.edu

    This file is part of the MDAT infrastructure.

    This program 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.

    This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#ifndef SEM_H
#define SEM_H

#include <string>
#include <vector>
#include <deque>
#include <semaphore.h>
using namespace std;

class SemaphoreManager
{
  public:

    void addSemaphore(const char *name, sem_t *sem, int value);

    void waitSemaphore(int id, sem_t *sem);

    void signalSemaphore(int id, sem_t *sem);

    string getSemaphoreTable() const;

  private:

    /* Semaphore data type */
    struct Semaphore {
      sem_t *sem;               // corresponding semaphore variable
      string name;              // name of the semaphore
      int value;                // value of the semaphore
      deque<int> waiting;       // queue of threads waiting on semaphore
    };

    vector<Semaphore> semArray;         // array of semaphores


    /* Finds and returns the desired semaphore record. */
    Semaphore* findSemaphore(sem_t *sp) {
      for (unsigned int i = 0; i < semArray.size(); i++) {
        if (semArray[i].sem == sp) return &semArray[i];
      }
      return NULL;
    }
    Semaphore* findSemaphore(string name) {
      for (unsigned int i = 0; i < semArray.size(); i++) {
        if (semArray[i].name == name) return &semArray[i];
      }
      return NULL;
    }

};

extern SemaphoreManager sems;

#endif