AuroraRuntime/Include/Aurora/IO/IOPipeRequest.hpp

/***
    Copyright (C) 2022 J Reece Wilson (a/k/a "Reece"). All rights reserved.

    File: IOPipeRequest.hpp
    Date: 2022-6-20
    Author: Reece
***/
#pragma once

namespace Aurora::IO
{
    struct IIOPipeEventListener;

    struct IOPipeRequest
    {
        /**
         * @brief Amount of bytes to transfer or zero if run until EoS/EoF
        */
        AuUInt32 uLengthOrZero {};

        /**
         * @brief true if the underlying stream uses relative stream positions
         *        (IE: a network or pipe stream that cannot seek backwards and fowards)
         *        (Inversely, file devices and similar IO subsystems use IO packets with absolute offsets)
        */
        bool bIsStream {false};

        /**
         * @brief internal frame size, that is one iteration of file or stream read, in bytes or zero if fallback
         *        Windows is inclined to read every single requested byte of a file stream asynchronously
         *        Streams, on all platforms, yield as soon as there is data available to copy over (usually)
        */
        AuUInt32 uPageLengthOrZero {};

        /**
         * @brief internal buffer size or zero if fallback
        */
        AuUInt32 uBufferLengthOrZero {};

        /**
         * @brief event listener
        */
        AuSPtr<IIOPipeEventListener> pListener;

        /**
         * @brief Minimum amount of bytes to read from the stream *if not identical to uLengthOrZero*
         * 
         *        Consider padded streams where only the content itself is read from a given interceptor;
         *        adjusting this variable permits for under-reads without failing the pipe transaction.
         * 
         * Recommended: 0 -> use uLengthOrZero
        */
        AuUInt32 uMinBytesToRead {};

        /**
         * @brief Used as the buffer size for streams of page length 0
        */
        static const AuUInt32 kFallbackPageSize {1024 * 1024 * 5};

        /**
         * @brief Used as the buffer size for streams of buffer length 0
        */
        static const AuUInt32 kFallbackBufferSize {1024 * 1024 * 50};
    };
}