OverflowPolicies.hpp

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#pragma once
 
#include <atomic>
#include <cassert>
#include <cstdint>
#include <exception>
#include <utility>
 
#include "corium/policies/QueuePolicies.hpp"
 
namespace corium {
 
struct DropNewestOverflowPolicy {
    template <typename QueuePolicy, typename EventVariant>
    bool handleOverflow(QueuePolicy& queue, EventVariant&& event, EventPriority priority = EventPriority::Normal)
    {
        (void)queue;
        (void)event;
        (void)priority;
        return false;
    }
};
 
struct DropOldestOverflowPolicy {
    template <typename QueuePolicy, typename EventVariant>
    bool handleOverflow(QueuePolicy& queue, EventVariant&& event, EventPriority priority = EventPriority::Normal)
    {
        typename QueuePolicy::EventType dummy;
        queue.tryPop(dummy); // Evict oldest event
        auto res = queue.tryPush(std::forward<EventVariant>(event), priority);
        return res.pushed;
    }
};
 
struct PanicOverflowPolicy {
    template <typename QueuePolicy, typename EventVariant>
    bool handleOverflow(QueuePolicy& queue, EventVariant&& event, EventPriority priority = EventPriority::Normal)
    {
        (void)queue;
        (void)event;
        (void)priority;
#if defined(CORIUM_PANIC_ON_OVERFLOW)
        std::terminate();
#else
        assert(false && "Corium Queue Overflow: Queue capacity exceeded!");
        return false;
#endif
    }
};
 
class AuditOverflowPolicy {
public:
    template <typename QueuePolicy, typename EventVariant>
    bool handleOverflow(QueuePolicy& queue, EventVariant&& event, EventPriority priority = EventPriority::Normal)
    {
        (void)queue;
        (void)event;
        (void)priority;
        _droppedCount.fetch_add(1, std::memory_order_relaxed);
        return false;
    }
 
    [[nodiscard]] uint64_t overflowCount() const noexcept
    {
        return _droppedCount.load(std::memory_order_relaxed);
    }
 
    void resetOverflowCount() noexcept
    {
        _droppedCount.store(0, std::memory_order_relaxed);
    }
 
private:
    std::atomic<uint64_t> _droppedCount{0};
};
 
} // namespace corium