/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/***************************************************************************
 *            queue.h
 *
 *  Tue Nov  9 10:57:20 CET 2004
 *  Copyright  2004 Bent Bisballe
 *  deva@aasimon.org
 ****************************************************************************/

/*
 * Originally from:
 * RTVideoRec Realtime video recoder and encoder for Linux
 *
 * Copyright (C) 2004  B. Stultiens
 */

/*
 *    This file is part of MIaV.
 *
 *    MIaV 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 2 of the License, or
 *    (at your option) any later version.
 *
 *    MIaV 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 MIaV; if not, write to the Free Software
 *    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
 */
#ifndef __RTVIDEOREC_QUEUE_H
#define __RTVIDEOREC_QUEUE_H

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
//#include <avformat.h>
//#include <avcodec.h>

#include "thread.h"
#include "util.h"

typedef struct __buf_t {
  struct __buf_t *next;
  struct __buf_t *prev;
  void *data;
} buf_t;


template<typename T>
class Queue {
public:
  Queue(int glimit = 0);
  ~Queue();

  void push(T *t);
  T *pop();
  T *peek();
  
  void lock();
  void unlock();

  int length();

private:
  volatile bool locked;
  int limit;
  buf_t *head;
  buf_t *tail;
  int count;
  pthread_mutex_t mutex;
  T *_pop();
};

/**
 * Initialize queue
 */
template<typename T>
Queue<T>::Queue(int glimit)
{
  locked = false;
  pthread_mutex_init (&mutex, NULL);
  limit = glimit;
  count = 0;
  head = NULL;
  tail = NULL;
}

/**
 * Clean up queue.
 */
template<typename T>
Queue<T>::~Queue()
{ 
  if(count != 0) {
    fprintf(stderr, "Queue not empty (%d)\n", count);
    while(T *t = _pop()) delete t;
  }
  pthread_mutex_destroy(&mutex);
}

/**
 * Push element on queue.
 */
template<typename T>
void Queue<T>::push(T *t)
{
  if(locked) {
    delete t;
    return;
  }

  pthread_mutex_lock(&mutex);

  buf_t *b = (buf_t*)xmalloc(sizeof(*b));
  b->data = (void*)t;

  assert(b != NULL);
  
  if(limit && count > 0) {
    T* tmp = (T*)_pop();
    delete tmp;
  }
  
  if(!head) {
    head = tail = b;
    b->next = b->prev = NULL;
    count = 1;
    pthread_mutex_unlock(&mutex);
    return;
  }
  
  b->next = tail;
  b->prev = NULL;
  if(tail)
    tail->prev = b;
  tail = b;
  count++;
  
  pthread_mutex_unlock(&mutex);
}

/**
 * Pop element from queue.
 * If queue is empty, NULL is returned.
 */
template<typename T>
T *Queue<T>::pop()
{
  pthread_mutex_lock(&mutex);
  T *d = _pop();
  pthread_mutex_unlock(&mutex);
  return d;
}

/**
 * Pop helper method
 * If queue is empty, NULL is returned.
 */
template<typename T>
T *Queue<T>::_pop()
{
  T *d;
  buf_t *b;

  assert(count >= 0);
  
  if(count == 0) {
    return NULL;
  }
  
  b = head;
  if(b->prev)
    b->prev->next = NULL;
  head = b->prev;
  if(b == tail)
    tail = NULL;
  count--;
  
  d = (T*)b->data;
  free(b);
  
  return d;
}

/**
 * Peek foremost element in queue
 * If queue is empty, NULL is returned.
 */
template<typename T>
T *Queue<T>::peek()
{
  //  pthread_mutex_lock(&mutex);
  T *d;

  //  assert(count >= 0);
  
  if(count == 0) {
    return NULL;
  }
  
  d = (T*)head->data;
  //  pthread_mutex_unlock(&mutex);
  return d;
}

/**
 * Print current length of queue
 */
template<typename T>
int Queue<T>::length()
{
  int length;
  pthread_mutex_lock(&mutex);
  length = count;
  pthread_mutex_unlock(&mutex);
  return length;
}

/**
 * Lock the queue (all elements pushed from this point will be deleted.)
 */
template<typename T>
void Queue<T>::lock()
{
  fprintf(stderr, "Lock this motherfucker..."); fflush(stderr);
  locked = true;
  fprintf(stderr, "done\n"); fflush(stderr);
}

/**
 * Unlock the queue.
 */
template<typename T>
void Queue<T>::unlock()
{
  fprintf(stderr, "Unlock this motherfucker..."); fflush(stderr);
  locked = false;
  fprintf(stderr, "done\n"); fflush(stderr);
}

#endif