Utilities.cs

// Copyright (c) .NET Foundation and Contributors (https://dotnetfoundation.org/ & https://stride3d.net) and Silicon Studio Corp. (https://www.siliconstudio.co.jp)
// Distributed under the MIT license. See the LICENSE.md file in the project root for more information.
//
// Copyright (c) 2010-2012 SharpDX - Alexandre Mutel
// 
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
using System;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Numerics;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using System.Threading;
using Stride.Core.Annotations;

namespace Stride.Core
{
    /// <summary>
    /// Utility class.
    /// </summary>
    public static class Utilities
    {
        /// <summary>
        /// Allocate an aligned memory buffer.
        /// </summary>
        /// <param name="sizeInBytes">Size of the buffer to allocate.</param>
        /// <param name="align">Alignment, a positive value which is a power of 2. 16 bytes by default.</param>
        /// <returns>A pointer to a buffer aligned.</returns>
        /// <remarks>
        /// To free this buffer, call <see cref="FreeMemory"/>
        /// </remarks>
        public static unsafe nint AllocateMemory(int sizeInBytes, int align = 16)
        {
            var mask = align - 1;
            if ((align & mask) != 0)
            {
                throw new ArgumentException("Alignment is not a power of 2.", nameof(align));
            }
            var memPtr = (nint)Marshal.AllocHGlobal(sizeInBytes + mask + sizeof(void*));
            var ptr = (memPtr + sizeof(void*) + mask) & ~mask;
            ((nint*)ptr)[-1] = memPtr;
            return ptr;
        }

        /// <summary>
        /// Allocate an aligned memory buffer and clear it with a specified value (0 by defaault).
        /// </summary>
        /// <param name="sizeInBytes">Size of the buffer to allocate.</param>
        /// <param name="clearValue">Default value used to clear the buffer.</param>
        /// <param name="align">Alignment, 16 bytes by default.</param>
        /// <returns>A pointer to a buffer aligned.</returns>
        /// <remarks>
        /// To free this buffer, call <see cref="FreeMemory"/>
        /// </remarks>
        public static unsafe nint AllocateClearedMemory(int sizeInBytes, byte clearValue = 0, int align = 16)
        {
            var ptr = AllocateMemory(sizeInBytes, align);
            Unsafe.InitBlockUnaligned((void*)ptr, clearValue, (uint)sizeInBytes);
            return ptr;
        }

        /// <summary>
        /// Determines whether the specified memory pointer is aligned in memory.
        /// </summary>
        /// <param name="memoryPtr">The memory pointer.</param>
        /// <param name="align">The align.</param>
        /// <returns><c>true</c> if the specified memory pointer is aligned in memory; otherwise, <c>false</c>.</returns>
        public static bool IsMemoryAligned(nint memoryPtr, int align = 16)
            => BitOperations.IsPow2(align)
            ? ((nint)memoryPtr & --align) == 0
            : throw new ArgumentException("Alignment is not a power of 2.", nameof(align));

        /// <summary>
        /// Free an aligned memory buffer.
        /// </summary>
        /// <remarks>
        /// The buffer must have been allocated with <see cref="AllocateMemory"/>
        /// </remarks>
        public static unsafe void FreeMemory(nint alignedBuffer)
            => Marshal.FreeHGlobal(((nint*)alignedBuffer)[-1]);

        /// <summary>
        /// If non-null, disposes the specified object and set it to null, otherwise do nothing.
        /// </summary>
        /// <param name="disposable">The disposable.</param>
        public static void Dispose<T>(ref T disposable) where T : class, IDisposable
        {
            if (disposable is not null)
            {
                disposable.Dispose();
                disposable = null;
            }
        }

        /// <summary>
        ///   Read stream to a byte[] buffer
        /// </summary>
        /// <param name = "stream">input stream</param>
        /// <returns>a byte[] buffer</returns>
        [Obsolete("Allocates. Read into the destination.")]
        public static byte[] ReadStream([NotNull] Stream stream)
        {
            Debug.Assert(stream != null);
            Debug.Assert(stream.CanRead);

            var readLength = (int)(stream.Length - stream.Position);

            Debug.Assert(readLength <= (stream.Length - stream.Position));

            if (readLength == 0)
            {
                return Array.Empty<byte>();
            }

            var buffer = new byte[readLength];
            var bytesRead = 0;

            while (bytesRead < readLength)
            {
                bytesRead += stream.Read(buffer, bytesRead, readLength - bytesRead);
            }

            return buffer;
        }

        /// <summary>
        /// Computes a hashcode for a dictionary.
        /// </summary>
        /// <returns>Hashcode for the list.</returns>
        public static int GetHashCode(IDictionary dict)
        {
            if (dict is null)
                return 0;

            var hashCode = 0;
            foreach (DictionaryEntry keyValue in dict)
            {
                hashCode = (hashCode * 397) ^ keyValue.Key.GetHashCode();
                hashCode = (hashCode * 397) ^ (keyValue.Value?.GetHashCode() ?? 0);
            }
            return hashCode;
        }

        /// <summary>
        /// Computes a hashcode for an enumeration
        /// </summary>
        /// <param name="it">An enumerator.</param>
        /// <returns>Hashcode for the list.</returns>
        public static int GetHashCode(IEnumerable it)
        {
            if (it is null)
                return 0;

            var hashCode = 0;
            foreach (var current in it)
            {
                hashCode = (hashCode * 397) ^ (current?.GetHashCode() ?? 0);
            }
            return hashCode;
        }

        /// <summary>
        /// Computes a hashcode for an enumeration
        /// </summary>
        /// <param name="it">An enumerator.</param>
        /// <returns>Hashcode for the list.</returns>
        public static int GetHashCode(IEnumerator it)
        {
            if (it is null)
                return 0;

            var hashCode = 0;
            while (it.MoveNext())
            {
                var current = it.Current;
                hashCode = (hashCode * 397) ^ (current?.GetHashCode() ?? 0);
            }
            return hashCode;
        }

        /// <summary>
        /// Compares two collection, element by elements.
        /// </summary>
        /// <param name="first">The collection to compare from.</param>
        /// <param name="second">The colllection to compare to.</param>
        /// <returns>True if lists are identical (but no necessarely of the same time). False otherwise.</returns>
        public static bool Compare<TKey, TValue>(IDictionary<TKey, TValue> first, IDictionary<TKey, TValue> second)
        {
            if (ReferenceEquals(first, second)) return true;
            if (first is null || second is null) return false;
            if (first.Count != second.Count) return false;

            var comparer = EqualityComparer<TValue>.Default;

            foreach (var keyValue in first)
            {
                if (!second.TryGetValue(keyValue.Key, out var secondValue)) return false;
                if (!comparer.Equals(keyValue.Value, secondValue)) return false;
            }

            // Check that all keys in second are in first
            return second.Keys.All(first.ContainsKey);
        }

        /// <summary>
        /// Compares two collection, element by elements.
        /// </summary>
        /// <param name="first">The collection to compare from.</param>
        /// <param name="second">The colllection to compare to.</param>
        /// <returns>True if lists are identical (but not necessarily in the same order). False otherwise.</returns>
        /// <remarks>Concrete SortedList is favored over interface to avoid enumerator object allocation.</remarks>
        public static bool Compare<TKey, TValue>(Collections.SortedList<TKey, TValue> first, Collections.SortedList<TKey, TValue> second)
        {
            if (ReferenceEquals(first, second)) return true;
            if (first is null || second is null) return false;
            if (first.Count != second.Count) return false;

            var comparer = EqualityComparer<TValue>.Default;

            foreach (var keyValue in first)
            {
                if (!second.TryGetValue(keyValue.Key, out var secondValue)) return false;
                if (!comparer.Equals(keyValue.Value, secondValue)) return false;
            }

            return true;
        }

        /// <summary>
        /// Swaps the value between two references.
        /// </summary>
        /// <typeparam name="T">Type of a data to swap.</typeparam>
        /// <param name="left">The left value.</param>
        /// <param name="right">The right value.</param>
        public static void Swap<T>(ref T left, ref T right) => (right, left) = (left, right);

        /// <summary>
        /// Linq assisted full tree iteration and collection in a single line.
        /// Warning, could be slow.
        /// </summary>
        /// <typeparam name="T">The type to iterate.</typeparam>
        /// <param name="root">The root item</param>
        /// <param name="childrenF">The function to retrieve a child</param>
        public static IEnumerable<T> IterateTree<T>(T root, Func<T, IEnumerable<T>> childrenF)
        {
            var q = new List<T> { root };
            while (q.Any())
            {
                var c = q[0];
                q.RemoveAt(0);
                q.AddRange(childrenF(c) ?? Enumerable.Empty<T>());
                yield return c;
            }
        }

        /// <summary>
        /// Converts a <see cref="Stopwatch" /> raw time to a <see cref="TimeSpan" />.
        /// </summary>
        /// <param name="delta">The delta.</param>
        /// <returns>The <see cref="TimeSpan" />.</returns>
        public static TimeSpan ConvertRawToTimestamp(long delta)
            => delta == 0 ? default : TimeSpan.FromTicks(delta * TimeSpan.TicksPerSecond / Stopwatch.Frequency);
    }
}