async_log_queue.h

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#pragma once

 
#include "fl/stl/int.h"
#include "fl/stl/noexcept.h"
#include "fl/stl/static_assert.h"
 
namespace fl {
 
class string;

template <fl::size DescriptorCount = 128, fl::size ArenaSize = 4096>
class AsyncLogQueue {
    // Compile-time assertions for power-of-2 sizes (enables cheap modulo with &)
    FL_STATIC_ASSERT((DescriptorCount & (DescriptorCount - 1)) == 0,
                  "DescriptorCount must be power of 2");
    FL_STATIC_ASSERT((ArenaSize & (ArenaSize - 1)) == 0,
                  "ArenaSize must be power of 2");
    FL_STATIC_ASSERT(DescriptorCount >= 4, "DescriptorCount must be >= 4");
    FL_STATIC_ASSERT(ArenaSize >= 32, "ArenaSize must be >= 32");
 
public:
    enum { MAX_MESSAGE_LENGTH = 512 };

    struct Descriptor {
        fl::u32 mStartIdx;  
        fl::u16 mLength;    
        fl::u16 mPadding;   
 
        Descriptor() FL_NOEXCEPT;
    };
 
    AsyncLogQueue() FL_NOEXCEPT;

    bool push(const fl::string& msg);

    bool push(const char* str);

    bool tryPop(const char** outPtr, fl::u16* outLen);

    void commit();

    fl::u32 droppedCount() const;

    fl::size size() const;

    bool empty() const;

    constexpr fl::size capacity() const {
        return DescriptorCount - 1;  // One slot reserved for full/empty distinction
    }
 
private:
    bool push(const char* str, fl::u16 len);
    static fl::u16 boundedStrlen(const char* str, fl::u16 maxLen);
    bool arenaHasSpace(fl::u32 aHead, fl::u32 aTail, fl::u16 len) const;
    fl::u32 loadHead() const;
    fl::u32 loadTail() const;
    fl::u32 loadArenaTail() const;
    void atomicIncDropped();
 
    // Member variables
    Descriptor mDescriptors[DescriptorCount];  
    char mArena[ArenaSize];                    
 
    // Ring indices (modified under critical section for memory ordering)
    volatile fl::u32 mHead;       
    volatile fl::u32 mTail;       
    volatile fl::u32 mArenaHead;  
    volatile fl::u32 mArenaTail;  
 
    volatile fl::u32 mDropped;    
};
 
} // namespace fl