Unity-WebSocket/Assets/FishNet/Runtime/Utility/Performance/BasicQueue.cs

//using System; //Remove on V5

//namespace FishNet.Utility.Performance
//{

//    /// <summary>
//    /// Unity 2022 has a bug where codegen will not compile when referencing a Queue type,
//    /// while also targeting .Net as the framework API.
//    /// As a work around this class is used for queues instead.
//    /// </summary>
//    public class BasicQueue<T>
//    {
//        /// <summary>
//        /// Maximum size of the collection.
//        /// </summary>
//        public int Capacity => Collection.Length;
//        /// <summary>
//        /// Number of elements in the queue.
//        /// </summary>
//        public int Count => _written;
//        /// <summary>
//        /// Collection containing data.
//        /// </summary>
//        private T[] Collection = new T[4];
//        /// <summary>
//        /// Current write index of the collection.
//        /// </summary>
//        public int WriteIndex { get; private set; }
//        /// <summary>
//        /// Buffer for resizing.
//        /// </summary>
//        private T[] _resizeBuffer = new T[0];
//        /// <summary>
//        /// Read position of the next Dequeue.
//        /// </summary>
//        private int _read;

//        /// <summary>
//        /// Length of the queue.
//        /// </summary>
//        private int _written;

//        /// <summary>
//        /// Enqueues an entry.
//        /// </summary>
//        /// <param name="data"></param>
//        public void Enqueue(T data)
//        {
//            if (_written == Collection.Length)
//                Resize();

//            if (WriteIndex >= Collection.Length)
//                WriteIndex = 0;
//            Collection[WriteIndex] = data;

//            WriteIndex++;
//            _written++;
//        }

//        /// <summary>
//        /// Tries to dequeue the next entry.
//        /// </summary>
//        /// <param name="result">Dequeued entry.</param>
//        /// <returns>True if an entry existed to dequeue.</returns>
//        public bool TryDequeue(out T result)
//        {
//            if (_written == 0)
//            {
//                result = default;
//                return false;
//            }

//            result = Dequeue();
//            return true;
//        }

//        /// <summary>
//        /// Dequeues the next entry.
//        /// </summary>
//        /// <returns></returns>
//        public T Dequeue()
//        {
//            if (_written == 0)
//                throw new Exception($"Queue of type {typeof(T).Name} is empty.");

//            T result = Collection[_read];

//            _written--;
//            _read++;
//            if (_read >= Collection.Length)
//                _read = 0;

//            return result;
//        }

//        /// <summary>
//        /// Tries to peek the next entry.
//        /// </summary>
//        /// <param name="result">Peeked entry.</param>
//        /// <returns>True if an entry existed to peek.</returns>
//        public bool TryPeek(out T result)
//        {
//            if (_written == 0)
//            {
//                result = default;
//                return false;
//            }

//            result = Peek();
//            return true;
//        }

//        /// <summary>
//        /// Peeks the next queue entry.
//        /// </summary>
//        /// <returns></returns>
//        public T Peek()
//        {
//            if (_written == 0)
//                throw new Exception($"Queue of type {typeof(T).Name} is empty.");

//            return Collection[_read];
//        }

//        /// <summary>
//        /// Clears the queue.
//        /// </summary>
//        public void Clear()
//        {
//            _read = 0;
//            WriteIndex = 0;
//            _written = 0;

//            DefaultCollection(Collection);
//            DefaultCollection(_resizeBuffer);

//            void DefaultCollection(T[] array)
//            {
//                int count = array.Length;
//                for (int i = 0; i < count; i++)
//                    array[i] = default;
//            }
//        }

//        /// <summary>
//        /// Doubles the queue size.
//        /// </summary>
//        private void Resize()
//        {
//            int length = _written;
//            int doubleLength = (length * 2);
//            int read = _read;

//            /* Make sure copy array is the same size as current
//             * and copy contents into it. */
//            //Ensure large enough to fit contents.
//            T[] resizeBuffer = _resizeBuffer;
//            if (resizeBuffer.Length < doubleLength)
//                Array.Resize(ref resizeBuffer, doubleLength);
//            //Copy from the read of queue first.
//            int copyLength = (length - read);
//            Array.Copy(Collection, read, resizeBuffer, 0, copyLength);
//            /* If read index was higher than 0
//             * then copy remaining data as well from 0. */
//            if (read > 0)
//                Array.Copy(Collection, 0, resizeBuffer, copyLength, read);

//            //Set _array to resize.
//            Collection = resizeBuffer;
//            //Reset positions.
//            _read = 0;
//            WriteIndex = length;
//        }

//        /// <summary>
//        /// Returns value in actual index as it relates to simulated index.
//        /// </summary>
//        /// <param name="simulatedIndex">Simulated index to return. A value of 0 would return the first simulated index in the collection.</param>
//        /// <returns></returns>
//        public T this[int simulatedIndex]
//        {
//            get
//            {
//                int offset = GetRealIndex(simulatedIndex);
//                return Collection[offset];
//            }
//            set
//            {
//                int offset = GetRealIndex(simulatedIndex);
//                Collection[offset] = value;
//            }
//        }



//        /// <summary>
//        /// Returns the real index of the collection using a simulated index.
//        /// </summary>
//        /// <param name="allowUnusedBuffer">True to allow an index be returned from an unused portion of the buffer so long as it is within bounds.</param>
//        private int GetRealIndex(int simulatedIndex, bool allowUnusedBuffer = false)
//        {
//            if (simulatedIndex >= Capacity)
//            {
//                return ReturnError();
//            }
//            else
//            {
//                int written = _written;
//                //May be out of bounds if allowUnusedBuffer is false.
//                if (simulatedIndex >= written)
//                {
//                    if (!allowUnusedBuffer)
//                        return ReturnError();
//                }
//                int offset = (Capacity - written) + simulatedIndex + WriteIndex;
//                if (offset >= Capacity)
//                    offset -= Capacity;

//                return offset;
//            }

//            int ReturnError()
//            {
//                UnityEngine.Debug.LogError($"Index {simulatedIndex} is out of range. Collection count is {_written}, Capacity is {Capacity}");
//                return -1;
//            }
//        }

//    }

//}