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async queue - overrun oldsest policy option

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gabime
2018-07-04 01:24:52 +03:00
parent 0358d115e0
commit 94a7152afc
4 changed files with 18 additions and 22 deletions
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23
include/spdlog/details/circular_q.h
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@@ -15,20 +15,20 @@ public:
using item_type = T;
explicit circular_q(size_t max_items)
: max_items_(max_items + 1)
: max_items_(max_items + 1) // one item is reserved as marker for full q
, v_(max_items_)
{
}
// push back, overrun last item if no room left
// push back, overrun (oldest) item if no room left
void push_back(T &&item)
{
v_[head_] = std::move(item);
head_ = (head_ + 1) % max_items_;
v_[tail_] = std::move(item);
tail_ = (tail_ + 1) % max_items_;
if (head_ == tail_)
if (tail_ == head_) // overrun last item if full
{
tail_ = (tail_ + 1) % max_items_;
head_ = (head_ + 1) % max_items_;
}
}
@@ -36,25 +36,26 @@ public:
// If there are no elements in the container, the behavior is undefined.
void pop_front(T &popped_item)
{
popped_item = std::move(v_[tail_]);
tail_ = (tail_ + 1) % max_items_;
popped_item = std::move(v_[head_]);
head_ = (head_ + 1) % max_items_;
}
bool empty()
{
return head_ == tail_;
return tail_ == head_;
}
bool full()
{
// tail is ahead of the head by 1
return ((head_ + 1) % max_items_) == tail_;
// head is ahead of the tail by 1
return ((tail_ + 1) % max_items_) == head_;
}
private:
size_t max_items_;
typename std::vector<T>::size_type head_ = 0;
typename std::vector<T>::size_type tail_ = 0;
std::vector<T> v_;
};
} // namespace details