#ifndef THREADMGR_H_
#define THREADMGR_H_

#include <pthread.h>		// has pthread_ routines

// ---- Class for "thread manager" to manage groups of threads -------

// (Caveat reader:  This class represents a first attempt at writing
//    a class to create and manage POSIX threads.  Experience with its
//    use might suggest improvements to the design and implementation.)

// ThreadObj must be a class that defines:
//   type "ptr" to itself
//   method "run" containing code for thread to execute, with
//     signature void run(void)
template <class ThreadObj>
class threadManager {
private:
  typedef typename ThreadObj::ptr tObjPtr;

public:

  // Constructor.
  // pre:  objs is an array of nThreads pointers to ThreadObj
  //         objects, properly initialized.
  // post:  threads have been constructed and started for all
  //          objects.
  threadManager(const int nThreads, tObjPtr objs[]) {
    numThreads = nThreads;
    threads = new pthread_t[numThreads];
    for (int i = 0; i < numThreads; ++i) 
      pthread_create(&threads[i], NULL, doRun, (void *) objs[i]);
  }

  // Destructor.
  ~threadManager(void) {
    delete [] threads;
  }

  // Wait for all threads to complete.
  void join(void) {
    for (int i = 0; i < numThreads; ++i)
      pthread_join(threads[i], NULL);
  }

private:

  // Make copy constructor and assignment operator private
  //   so they can't be used (since it's not clear this would 
  //   make sense).
  threadManager(const threadManager & t);
  threadManager & operator= (const threadManager & t);

  // Wrapper for thread object's "run" method.
  static void * doRun(void * argPtr) {
    tObjPtr objPtr = (tObjPtr) argPtr;
    objPtr->run();
    pthread_exit((void *) NULL);
  }

  // Member variables.
  int numThreads;		// number of threads
  pthread_t * threads;		// "handles" for threads

};

#endif // THREADMGR_H_