improved performance of XxHash3

Wsm2110 · Nov 1, 2024 · 5cb2de7 · 5cb2de7
1 parent 92a5788
commit 5cb2de7
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Showing 6 changed files with 27 additions and 29 deletions.
diff --git a/benchmarks/Faster.Map.Benchmark/StringBenchmark.cs b/benchmarks/Faster.Map.Benchmark/StringBenchmark.cs
@@ -26,7 +26,7 @@ public class StringBenchmark
 
         #region Properties
 
-        [Params(1000, 10000, 100000, 400000, 900000, 1000000)]
+        [Params(/*1000, 10000, 100000, 400000, 900000,*/ 1000000)]
         public uint Length { get; set; }
 
         #endregion
@@ -51,7 +51,7 @@ public void Setup()
             uint length = BitOperations.RoundUpToPowerOf2(Length) * 2;
             int dicLength = HashHelpers.GetPrime((int)Length);
 
-            _denseMap = new DenseMap<string, string>(length, 0875, new StringHasher());
+            _denseMap = new DenseMap<string, string>(length, 0.875, new XxHash3StringHasher());
             _dictionary = new Dictionary<string, string>(dicLength);
             _robinhoodMap = new RobinhoodMap<string, string>(length);
 

diff --git a/benchmarks/Faster.Map.Benchmark/StringWrapperBenchmark.cs b/benchmarks/Faster.Map.Benchmark/StringWrapperBenchmark.cs
@@ -25,7 +25,7 @@ public class StringWrapperBenchmark
 
         #region Properties
 
-        [Params(1000, 10000, 100000, 400000, 900000, 1000000)]
+        [Params(/*1000, 10000, 100000, 400000, 900000,*/ 1000000)]
         public uint Length { get; set; }
 
         #endregion
@@ -71,23 +71,23 @@ public void DenseMap()
             }
         }
 
-        [Benchmark]
-        public void RobinhoodMap()
-        {
-            foreach (var key in keys)
-            {
-                _robinhoodMap.Get(key, out var result);
-            }
-        }
-
-        [Benchmark]
-        public void Dictionary()
-        {
-            foreach (var key in keys)
-            {
-                _dictionary.TryGetValue(key, out var result);
-            }
-        }
+        //[Benchmark]
+        //public void RobinhoodMap()
+        //{
+        //    foreach (var key in keys)
+        //    {
+        //        _robinhoodMap.Get(key, out var result);
+        //    }
+        //}
+
+        //[Benchmark]
+        //public void Dictionary()
+        //{
+        //    foreach (var key in keys)
+        //    {
+        //        _dictionary.TryGetValue(key, out var result);
+        //    }
+        //}
 
     }
 }
diff --git a/src/DenseMap.cs b/src/DenseMap.cs
@@ -4,7 +4,6 @@
 #if NET7_0_OR_GREATER
 
 using Faster.Map.Contracts;
-using Faster.Map.Core;
 using Faster.Map.Hasher;
 using System;
 using System.Collections.Generic;

diff --git a/src/Hasher/XxHash3Hasher.cs b/src/Hasher/XxHash3Hasher.cs
@@ -11,8 +11,8 @@ public class XxHash3Hasher<T> : IHasher<T> where T : unmanaged
         public uint ComputeHash(T key)
         {
             var span = MemoryMarshal.AsBytes(MemoryMarshal.CreateReadOnlySpan(ref Unsafe.AsRef(key), 1));
-            var result = XxHash3.Hash(MemoryMarshal.AsBytes(span));
-            return Unsafe.ReadUnaligned<uint>(ref result[0]);
+            var result = XxHash3.HashToUInt64(MemoryMarshal.AsBytes(span)) >> 32;
+            return Unsafe.As<ulong, uint>(ref result);         
         }
     }
 }
diff --git a/src/Hasher/StringHasher.cs → src/Hasher/XxHash3StringHasher.cs b/src/Hasher/StringHasher.cs → src/Hasher/XxHash3StringHasher.cs
@@ -6,14 +6,13 @@
 
 namespace Faster.Map.Hasher
 {
-    public class StringHasher : IHasher<string>
+    public class XxHash3StringHasher : IHasher<string>
     {
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public uint ComputeHash(string key)
         {
-            var span = key.AsSpan();
-            var result = XxHash3.Hash(MemoryMarshal.AsBytes(span));
-            return Unsafe.ReadUnaligned<uint>(ref result[0]);
+            var result = XxHash3.HashToUInt64(MemoryMarshal.AsBytes(key.AsSpan())) >> 32;
+            return Unsafe.As<ulong, uint>(ref result);
         }
     }
 }
diff --git a/unittests/Faster.Map.DenseMap.Tests/StringHasherTests.cs b/unittests/Faster.Map.DenseMap.Tests/StringHasherTests.cs
@@ -13,7 +13,7 @@ public class StringHasherTests
 
         public StringHasherTests()
         {
-            _map = new DenseMap<string, string>(16, 0.875, new StringHasher());
+            _map = new DenseMap<string, string>(16, 0.875, new XxHash3StringHasher());
         }
 
         [Fact]
@@ -170,7 +170,7 @@ public void Indexer_Set_UpdatesValueForExistingStringKey()
         [Fact]
         public void LoadFactorLimit_DoesNotExceedForStringKeys()
         {
-            var result = new DenseMap<string, string>(4, 0.75, new StringHasher());
+            var result = new DenseMap<string, string>(4, 0.75, new XxHash3StringHasher());
 
             result.Emplace("key1", "value1");
             result.Emplace("key2", "value2");