/**
 * encapsulate array_lock_free_queue, add semphore. populate in kernal space.
 */
#ifndef __LOCK_FREE_QUEUE_H__
#define __LOCK_FREE_QUEUE_H__

#include <usg_common.h>
#include <assert.h> // assert()
#include "shm_mm.h"
#include "sem_util.h"
#include "logger_factory.h"
#include "shm_allocator.h"
#include "psem.h"
#include "bus_error.h"
#include "bus_def.h"

// default Queue size
#define LOCK_FREE_Q_DEFAULT_SIZE 16


#define LOCK_FREE_Q_ST_OPENED 0

#define LOCK_FREE_Q_ST_CLOSED 1

// static Logger *logger = LoggerFactory::getLogger();
// define this macro if calls to "size" must return the real size of the
// queue. If it is undefined  that function will try to take a snapshot of
// the queue, but returned value might be bogus


// forward declarations for default template values
//

template<typename ELEM_T, typename Allocator>
class ArrayLockFreeQueue;

// template <typename ELEM_T>
// class LinkedLockFreeQueue;


/// @brief Lock-free queue based on a circular array
/// No allocation of extra memory for the nodes handling is needed, but it has
/// to add extra overhead (extra CAS operation) when inserting to ensure the
/// thread-safety of the queue when the queue type is not
/// ArrayLockFreeQueueSingleProducer.
///
/// examples of instantiation:
///   ArrayLockFreeQueue<int> q; // queue of ints of default size (65535 - 1)
///                              // and defaulted to single producer
///   ArrayLockFreeQueue<int, 16> q;
///                              // queue of ints of size (16 - 1) and
///                              // defaulted to single producer
///   ArrayLockFreeQueue<int, 100, ArrayLockFreeQueue> q;
///                              // queue of ints of size (100 - 1) with support
///                              // for multiple producers
///
/// ELEM_T represents the type of elementes pushed and popped from the queue
/// Q_SIZE size of the queue. The actual size of the queue is (Q_SIZE-1)
///        This number should be a power of 2 to ensure
///        indexes in the circular queue keep stable when the uint32_t
///        variable that holds the current position rolls over from FFFFFFFF
///        to 0. For instance
///        2    -> 0x02
///        4    -> 0x04
///        8    -> 0x08
///        16   -> 0x10
///        (...)
///        1024 -> 0x400
///        2048 -> 0x800
///
///        if queue size is not defined as requested, let's say, for
///        instance 100, when current position is FFFFFFFF (4,294,967,295)
///        index in the circular array is 4,294,967,295 % 100 = 95.
///        When that value is incremented it will be set to 0, that is the
///        last 4 elements of the queue are not used when the counter rolls
///        over to 0
/// Q_TYPE type of queue implementation. ArrayLockFreeQueueSingleProducer and
///        ArrayLockFreeQueue are supported (single producer
///        by default)
template<
  typename ELEM_T,
  typename Allocator = SHM_Allocator,
  template<typename T, typename AT> class Q_TYPE = ArrayLockFreeQueue
>
class LockFreeQueue {

private:
  sem_t slots;
  sem_t items;

  time_t createTime;
  time_t closeTime;
  int status;

public:

  LockFreeQueue(size_t qsize = LOCK_FREE_Q_DEFAULT_SIZE);

  /// @brief destructor of the class.
  /// Note it is not virtual since it is not expected to inherit from this
  /// template
  ~LockFreeQueue();

  inline void  close();

  // std::atomic_uint reference;
  /// @brief constructor of the class


  /// @brief returns the current number of items in the queue
  /// It tries to take a snapshot of the size of the queue, but in busy environments
  /// this function might return bogus values.
  ///
  /// If a reliable queue size must be kept you might want to have a look at
  /// the preprocessor variable in this header file called '_WITH_LOCK_FREE_Q_KEEP_REAL_SIZE'
  /// it enables a reliable size though it hits overall performance of the queue
  /// (when the reliable size variable is on it's got an impact of about 20% in time)
  inline uint32_t size();

  /// @brief return true if the queue is full. False otherwise
  /// It tries to take a snapshot of the size of the queue, but in busy
  /// environments this function might return bogus values. See help in method
  /// LockFreeQueue::size
  inline bool full();

  inline bool empty();

  inline ELEM_T &operator[](unsigned i);

  

  time_t getCreateTime() {
    return createTime;
  }

  time_t getCloseTime() {
    return closeTime;
  }

  int getStatus() {
    return status;
  }

  /// @brief push an element at the tail of the queue
  /// @param the element to insert in the queue
  /// Note that the element is not a pointer or a reference, so if you are using large data
  /// structures to be inserted in the queue you should think of instantiate the template
  /// of the queue as a pointer to that large structure
  /// @return true if the element was inserted in the queue. False if the queue was full
  int push(const ELEM_T &a_data, const struct timespec *timeout = NULL, int flag = 0);

  /// @brief pop the element at the head of the queue
  /// @param a reference where the element in the head of the queue will be saved to
  /// Note that the a_data parameter might contain rubbish if the function returns false
  /// @return true if the element was successfully extracted from the queue. False if the queue was empty
  int pop(ELEM_T &a_data, const struct timespec *timeout = NULL, int flag = 0);


  void *operator new(size_t size);

  void operator delete(void *p);

protected:
  /// @brief the actual queue. methods are forwarded into the real
  ///        implementation
  Q_TYPE<ELEM_T, Allocator> m_qImpl;

private:
  /// @brief disable copy constructor declaring it private
  LockFreeQueue<ELEM_T, Allocator, Q_TYPE>(const LockFreeQueue<ELEM_T, Allocator, Q_TYPE> &a_src);
};


template<
  typename ELEM_T,
  typename Allocator,
  template<typename T, typename AT> class Q_TYPE>
LockFreeQueue<ELEM_T, Allocator, Q_TYPE>::LockFreeQueue(size_t qsize): m_qImpl(qsize) {
  // std::cout << "LockFreeQueue init reference=" << reference << std::endl;
  if (sem_init(&slots, 1, qsize) == -1)
    err_exit(errno, "LockFreeQueue sem_init");
  if (sem_init(&items, 1, 0) == -1)
    err_exit(errno, "LockFreeQueue sem_init");
  
  createTime = time(NULL);
  status = LOCK_FREE_Q_ST_OPENED;

}


template<
  typename ELEM_T,
  typename Allocator,
  template<typename T, typename AT> class Q_TYPE>
inline void LockFreeQueue<ELEM_T, Allocator, Q_TYPE>::close() {
  status = LOCK_FREE_Q_ST_CLOSED;
  closeTime = time(NULL); 
}


template<
  typename ELEM_T,
  typename Allocator,
  template<typename T, typename AT> class Q_TYPE>
LockFreeQueue<ELEM_T, Allocator, Q_TYPE>::~LockFreeQueue() {
  // LoggerFactory::getLogger()->debug("LockFreeQueue desctroy");
  if (sem_destroy(&slots) == -1) {
    err_exit(errno, "LockFreeQueue sem_destroy");
  }
  if (sem_destroy(&items) == -1) {
    err_exit(errno, "LockFreeQueue sem_destroy");
  }
  
}

template<
  typename ELEM_T,
  typename Allocator,
  template<typename T, typename AT> class Q_TYPE>
inline uint32_t LockFreeQueue<ELEM_T, Allocator, Q_TYPE>::size() {
  return m_qImpl.size();
}

template<
  typename ELEM_T,
  typename Allocator,
  template<typename T, typename AT> class Q_TYPE>
inline bool LockFreeQueue<ELEM_T, Allocator, Q_TYPE>::full() {
  return m_qImpl.full();
}

template<
  typename ELEM_T,
  typename Allocator,
  template<typename T, typename AT> class Q_TYPE>
inline bool LockFreeQueue<ELEM_T, Allocator, Q_TYPE>::empty() {
  return m_qImpl.empty();
}


template<typename ELEM_T,
  typename Allocator,
  template<typename T, typename AT> class Q_TYPE>
int LockFreeQueue<ELEM_T, Allocator, Q_TYPE>::push(const ELEM_T &a_data, const struct timespec *timeout, int flag) {
  // LoggerFactory::getLogger()->debug("==================LockFreeQueue push before\n");
  // sigset_t mask_all, pre;
  // sigfillset(&mask_all);

  // sigprocmask(SIG_BLOCK, &mask_all, &pre);

  if ((flag & BUS_NOWAIT_FLAG) == BUS_NOWAIT_FLAG) {
    if (psem_trywait(&slots) == -1) {
      goto LABEL_FAILTURE;
    }
  } else if ((flag & BUS_TIMEOUT_FLAG) == BUS_TIMEOUT_FLAG && timeout != NULL) {
    if (psem_timedwait(&slots, timeout) == -1) {
      goto LABEL_FAILTURE;
    }
  } else {
    if (psem_wait(&slots) == -1) {
      goto LABEL_FAILTURE;
    }
  }


  if (m_qImpl.push(a_data)) {
    psem_post(&items);
    // sigprocmask(SIG_SETMASK, &pre, NULL);
    // LoggerFactory::getLogger()->debug("==================LockFreeQueue push after\n");
    return 0;
  }

  LABEL_FAILTURE:
  // sigprocmask(SIG_SETMASK, &pre, NULL);
  return errno;
}

template<typename ELEM_T,
  typename Allocator,
  template<typename T, typename AT> class Q_TYPE>
int LockFreeQueue<ELEM_T, Allocator, Q_TYPE>::pop(ELEM_T &a_data, const struct timespec *timeout, int flag) {
  // LoggerFactory::getLogger()->debug("==================LockFreeQueue pop before....");

  // sigset_t mask_all, pre;
  // sigfillset(&mask_all);

  // sigprocmask(SIG_BLOCK, &mask_all, &pre);

  if ((flag & BUS_NOWAIT_FLAG) == BUS_NOWAIT_FLAG) {
    if (psem_trywait(&items) == -1) {
      goto LABEL_FAILTURE;
    }
  } else if ((flag & BUS_TIMEOUT_FLAG) == BUS_TIMEOUT_FLAG && timeout != NULL) {
    // LoggerFactory::getLogger()->debug("==================LockFreeQueue pop before. flag=%d ,  %d\n", flag, timeout->tv_sec);
    if (psem_timedwait(&items, timeout) == -1) {
      goto LABEL_FAILTURE;
    }
  } else {
    if (psem_wait(&items) == -1) {
      goto LABEL_FAILTURE;
    }
  }

  if (m_qImpl.pop(a_data)) {
    psem_post(&slots);
    // sigprocmask(SIG_SETMASK, &pre, NULL);
    // LoggerFactory::getLogger()->debug("==================LockFreeQueue pop after\n");
    return 0;
  }


  LABEL_FAILTURE:
  // sigprocmask(SIG_SETMASK, &pre, NULL);
  return errno;
}

template<typename ELEM_T,
  typename Allocator,
  template<typename T, typename AT> class Q_TYPE>
ELEM_T &LockFreeQueue<ELEM_T, Allocator, Q_TYPE>::operator[](unsigned i) {
  return m_qImpl.operator[](i);
}


template<typename ELEM_T,
  typename Allocator,
  template<typename T, typename AT> class Q_TYPE>
void *LockFreeQueue<ELEM_T, Allocator, Q_TYPE>::operator new(size_t size) {
  return Allocator::allocate(size);
}

template<typename ELEM_T,
  typename Allocator,
  template<typename T, typename AT> class Q_TYPE>
void LockFreeQueue<ELEM_T, Allocator, Q_TYPE>::operator delete(void *p) {
  LockFreeQueue<ELEM_T, Allocator, Q_TYPE> * _que =  (LockFreeQueue<ELEM_T, Allocator, Q_TYPE> * )p;
  Allocator::deallocate(p);
}

// include implementation files
//#include "linked_lock_free_queue.h"
#include "array_lock_free_queue.h"

#endif // _LOCK_FREE_QUEUE_H__