wait_free_array_value_pool-inl.h

/*
 * Copyright (c) 2014-2016, Siemens AG. All rights reserved.
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 * modification, are permitted provided that the following conditions are met:
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#ifndef EMBB_CONTAINERS_INTERNAL_WAIT_FREE_ARRAY_VALUE_POOL_INL_H_
#define EMBB_CONTAINERS_INTERNAL_WAIT_FREE_ARRAY_VALUE_POOL_INL_H_

namespace embb {
namespace containers {
template<typename Type, Type Undefined, class Allocator >
void WaitFreeArrayValuePool<Type, Undefined, Allocator>::
Free(Type element, int index) {
  assert(element != Undefined);

  // Just put back the element
  pool_array_[index].Store(element);
}

template<typename Type, Type Undefined, class Allocator >
int WaitFreeArrayValuePool<Type, Undefined, Allocator>::
Allocate(Type & element) {
  for (int i = 0; i != size_; ++i) {
    Type expected;

    // If the memory cell is not available, go ahead
    if (Undefined == (expected = pool_array_[i].Load()))
      continue;

    // Try to get the memory cell
    if (pool_array_[i].CompareAndSwap(expected, Undefined)) {
      // When the CAS was successful, this element is ours
      element = expected;
      return i;
    }
  }
  return -1;
}

template<typename Type, Type Undefined, class Allocator >
template<typename ForwardIterator>
WaitFreeArrayValuePool<Type, Undefined, Allocator>::
WaitFreeArrayValuePool(ForwardIterator first, ForwardIterator last) {
  size_t dist = static_cast<size_t>(std::distance(first, last));

  size_ = static_cast<int>(dist);

  // conversion may result in negative number. check!
  assert(size_ >= 0);

  // Use the allocator to allocate an array of size dist
  pool_array_ = allocator_.allocate(dist);

  // invoke inplace new for each pool element
  for ( size_t i = 0; i != dist; ++i ) {
    new (&pool_array_[i]) embb::base::Atomic<Type>();
  }

  int i = 0;

  // Store the elements of the range
  for (ForwardIterator curIter(first); curIter != last; ++curIter) {
    pool_array_[i++] = *curIter;
  }
}

template<typename Type, Type Undefined, class Allocator >
WaitFreeArrayValuePool<Type, Undefined, Allocator>::~WaitFreeArrayValuePool() {
  // invoke destructor for each pool element
  for (int i = 0; i != size_; ++i) {
    pool_array_[i].~Atomic();
  }

  // free memory
  allocator_.deallocate(pool_array_, static_cast<size_t>(size_));
}

template<typename Type, Type Undefined, class Allocator >
size_t WaitFreeArrayValuePool<Type, Undefined, Allocator>::
GetMinimumElementCountForGuaranteedCapacity(size_t capacity) {
  // for this value pool, this is just capacity...
  return capacity;
}

} // namespace containers
} // namespace embb

#endif  // EMBB_CONTAINERS_INTERNAL_WAIT_FREE_ARRAY_VALUE_POOL_INL_H_