Method Free

be/src/runtime/bufferpool/suballocator.cc:153–178

}

void Suballocator::Free(unique_ptr<Suballocation> allocation) {
  if (allocation == nullptr) return;

  DCHECK(allocation->in_use_);
  allocation->in_use_ = false;
  allocated_ -= allocation->len_;

  // Iteratively coalesce buddies until the buddy is in use or we get to the root.
  // This ensures that all buddies in the free lists are coalesced. I.e. we do not
  // have two buddies in the same free list.
  unique_ptr<Suballocation> curr_allocation = move(allocation);
  while (curr_allocation->buddy_ != nullptr) {
    if (curr_allocation->buddy_->in_use_) {
      // If the buddy is not free we can't coalesce, just add it to free list.
      AddToFreeList(move(curr_allocation));
      return;
    }
    unique_ptr<Suballocation> buddy = RemoveFromFreeList(curr_allocation->buddy_);
    curr_allocation = CoalesceBuddies(move(curr_allocation), move(buddy));
  }

  // Reached root, which is an entire free buffer. We are not using it, so free up memory.
  DCHECK(curr_allocation->buffer_.is_open());
  pool_->FreeBuffer(client_, &curr_allocation->buffer_);
  curr_allocation.reset();
}

void Suballocator::AddToFreeList(unique_ptr<Suballocation> node) {
  DCHECK(!node->in_use_);