From 67630e3797c1352be4d77e0012f1cecef37f4e3c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marek=20Lema=C5=84czyk?= <marek@lemanczyk.eu>
Date: Tue, 29 Jul 2025 17:07:17 +0200
Subject: [PATCH] Optimize AddRange copy

---
 .../RecyclablePriorityQueue.AddRange.cs       | 94 +++++++++++++++++++
 .../RecyclablePriorityQueueTests.cs           | 50 ++++++++++
 2 files changed, 144 insertions(+)
 create mode 100644 Recyclable.Collections/RecyclablePriorityQueue.AddRange.cs

diff --git a/Recyclable.Collections/RecyclablePriorityQueue.AddRange.cs b/Recyclable.Collections/RecyclablePriorityQueue.AddRange.cs
new file mode 100644
index 0000000..6c759aa
--- /dev/null
+++ b/Recyclable.Collections/RecyclablePriorityQueue.AddRange.cs
@@ -0,0 +1,94 @@
+using System.Runtime.CompilerServices;
+using System.Numerics;
+using Recyclable.Collections.Pools;
+
+namespace Recyclable.Collections
+{
+    internal static class zRecyclablePriorityQueueAddRange
+    {
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static void EnsureCapacity<T>(RecyclablePriorityQueue<T> queue, int min)
+        {
+            if (queue._heap.Length >= min)
+            {
+                return;
+            }
+
+            int newSize = queue._heap.Length;
+            do
+            {
+                if (newSize >= RecyclableDefaults.MaxPooledBlockSize)
+                {
+                    newSize = RecyclableDefaults.MaxPooledBlockSize;
+                    break;
+                }
+
+                newSize <<= 1;
+            }
+            while (newSize < min);
+
+            if (newSize < min)
+            {
+                newSize = min;
+            }
+
+            T[] newHeap = newSize >= RecyclableDefaults.MinPooledArrayLength
+                ? RecyclableArrayPool<T>.RentShared(newSize)
+                : new T[newSize];
+            System.Array.Copy(queue._heap, newHeap, queue._size);
+
+            if (queue._heap.Length >= RecyclableDefaults.MinPooledArrayLength)
+            {
+                RecyclableArrayPool<T>.ReturnShared(queue._heap, RecyclablePriorityQueue<T>._needsClearing);
+            }
+
+            queue._heap = newHeap;
+        }
+
+        [MethodImpl(MethodImplOptions.NoInlining | MethodImplOptions.AggressiveOptimization)]
+        internal static void AddRange<T>(this RecyclablePriorityQueue<T> queue, ReadOnlySpan<T> items)
+        {
+            int count = items.Length;
+            if (count == 0)
+            {
+                return;
+            }
+
+            int startIndex = queue._size;
+            int newCount = startIndex + count;
+            EnsureCapacity(queue, newCount);
+
+            for (int i = 0; i < count; i++)
+            {
+                queue._heap[startIndex + i] = items[i];
+            }
+            queue._size = newCount;
+
+            int half = newCount >> 1;
+            for (int i = half - 1; i >= 0; i--)
+            {
+                int index = i;
+                T item = queue._heap[index];
+                while (index < half)
+                {
+                    int child = (index << 1) + 1;
+                    int right = child + 1;
+                    if (right < newCount && queue._comparer.Compare(queue._heap[right], queue._heap[child]) < 0)
+                    {
+                        child = right;
+                    }
+
+                    if (queue._comparer.Compare(queue._heap[child], item) >= 0)
+                    {
+                        break;
+                    }
+
+                    queue._heap[index] = queue._heap[child];
+                    index = child;
+                }
+
+                queue._heap[index] = item;
+            }
+        }
+    }
+}
diff --git a/Recyclable.CollectionsTests/RecyclablePriorityQueueTests.cs b/Recyclable.CollectionsTests/RecyclablePriorityQueueTests.cs
index b9a1df2..1870586 100644
--- a/Recyclable.CollectionsTests/RecyclablePriorityQueueTests.cs
+++ b/Recyclable.CollectionsTests/RecyclablePriorityQueueTests.cs
@@ -52,5 +52,55 @@ namespace Recyclable.CollectionsTests
             using var queue = new RecyclablePriorityQueue<int>();
             _ = Assert.Throws<ArgumentOutOfRangeException>(() => queue.Dequeue());
         }
+
+        [Fact]
+        public void AddRangeSpanShouldAddItemsInSortedOrder()
+        {
+            using var queue = new RecyclablePriorityQueue<int>();
+            queue.AddRange((ReadOnlySpan<int>)_testData);
+
+            var result = new List<int>();
+            while (queue.LongCount > 0)
+            {
+                result.Add(queue.Dequeue());
+            }
+
+            _ = result.Should().Equal(_testData.Order());
+        }
+
+        [Fact]
+        public void AddRangeSpanShouldDoNothingWhenEmpty()
+        {
+            using var queue = new RecyclablePriorityQueue<int>();
+            queue.AddRange(ReadOnlySpan<int>.Empty);
+            _ = queue.Should().BeEmpty();
+        }
+
+        [Fact]
+        public void AddRangeSpanShouldNotOverrideItems()
+        {
+            using var queue = new RecyclablePriorityQueue<int>();
+            queue.AddRange((ReadOnlySpan<int>)_testData);
+            queue.AddRange((ReadOnlySpan<int>)_testData);
+
+            var expected = _testData.Concat(_testData).Order().ToArray();
+            var result = new List<int>();
+            while (queue.LongCount > 0)
+            {
+                result.Add(queue.Dequeue());
+            }
+
+            _ = result.Should().Equal(expected);
+        }
+
+        [Fact]
+        public void AddRangeShouldAcceptNulls()
+        {
+            using var queue = new RecyclablePriorityQueue<long?>();
+            queue.AddRange(new long?[] { null, 1 });
+            _ = queue.Should().HaveCount(2).And.Contain((long?)null);
+        }
+
     }
 }
+