Use ByteArrayComparer

bezysoftware · Oct 29, 2024 · d2f959c · d2f959c
1 parent 96f9071
commit d2f959c
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Showing 2 changed files with 30 additions and 9 deletions.
diff --git a/src/Negentropy/ByteArrayComparer.cs b/src/Negentropy/ByteArrayComparer.cs
@@ -1,6 +1,8 @@
-namespace Negentropy
+using System.Diagnostics.CodeAnalysis;
+
+namespace Negentropy
 {
-    internal class ByteArrayComparer : IComparer<byte[]>
+    internal class ByteArrayComparer : IComparer<byte[]>, IEqualityComparer<byte[]>
     {
         public int Compare(byte[]? x, byte[]? y)
         {
@@ -18,6 +20,23 @@ public int Compare(byte[]? x, byte[]? y)
             return 0;
         }
 
+        public bool Equals(byte[]? x, byte[]? y)
+        {
+            return Compare(x, y) == 0;
+        }
+
+        public int GetHashCode([DisallowNull] byte[] a)
+        {
+            uint b = 0;
+
+            for (int i = 0; i < a.Length; i++)
+            {
+                b = ((b << 23) | (b >> 9)) ^ a[i];
+            }
+
+            return unchecked((int)b);
+        }
+
         public static ByteArrayComparer Instance { get; } = new ByteArrayComparer();
     }
 }
diff --git a/src/Negentropy/Negentropy.cs b/src/Negentropy/Negentropy.cs
@@ -1,4 +1,5 @@
 using System.Collections;
+using System.Linq;
 
 namespace Negentropy
 {
@@ -10,6 +11,7 @@ public class Negentropy
         const byte PROTOCOL_VERSION = 0x61; // Version 1
         const int BUCKETS = 16;
         const int ID_SIZE = 32;
+        const int RESERVE = 200;
 
         private readonly Bound[] items;
         private readonly NegentropyOptions options;
@@ -114,7 +116,7 @@ public NegentropyReconciliation Reconcile(string query)
                         var theirFingerprint = reader.ReadBytes(Fingerprint.SIZE);
                         var ouringerprint = Fingerprint.Calculate(this.items, lower, upper);
 
-                        if (StructuralComparisons.StructuralEqualityComparer.Equals(theirFingerprint, ouringerprint))
+                        if (ByteArrayComparer.Instance.Equals(theirFingerprint, ouringerprint))
                         {
                             skip = true;
                         }
@@ -126,7 +128,7 @@ public NegentropyReconciliation Reconcile(string query)
                         break;
                     case Mode.IdList:
                         var count = reader.ReadVarInt();
-                        var theirIds = new HashSet<byte[]>();
+                        var theirIds = new HashSet<byte[]>(ByteArrayComparer.Instance);
 
                         for (var i = 0L; i < count; i++)
                         {
@@ -145,10 +147,10 @@ public NegentropyReconciliation Reconcile(string query)
                                 .Skip(lower)
                                 .Take(upper - lower)
                                 .Select(x => x.Id)
-                                .ToArray();
+                                .ToHashSet(ByteArrayComparer.Instance);
 
-                            haveIds.AddRange(ourIds.Where(our => !theirIds.Any(their => StructuralComparisons.StructuralEqualityComparer.Equals(our, their))));
-                            needIds.AddRange(theirIds.Where(their => !ourIds.Any(our => StructuralComparisons.StructuralEqualityComparer.Equals(our, their))));
+                            haveIds.AddRange(ourIds.Where(our => !theirIds.Contains(our)));
+                            needIds.AddRange(theirIds.Where(their => !ourIds.Contains(their)));
                         }
                         else
                         {
@@ -157,7 +159,7 @@ public NegentropyReconciliation Reconcile(string query)
                             var endBound = bound;
                             var spaceLeft = this.options.FrameSizeLimit == 0
                                 ? int.MaxValue
-                                : (int)((this.options.FrameSizeLimit - 200 - writer.BaseStream.Position) / ID_SIZE);
+                                : (int)((this.options.FrameSizeLimit - RESERVE - writer.BaseStream.Position) / ID_SIZE);
 
                             var responseIds = this.items
                                 .Skip(lower)
@@ -177,7 +179,7 @@ public NegentropyReconciliation Reconcile(string query)
                         throw new InvalidOperationException("Unexpected mode");
                 }
 
-                if (this.options.FrameSizeLimit > 0 && writer.BaseStream.Position > this.options.FrameSizeLimit - 200)
+                if (this.options.FrameSizeLimit > 0 && writer.BaseStream.Position > this.options.FrameSizeLimit - RESERVE)
                 {
                     var remainingFingerprint = Fingerprint.Calculate(this.items, upper, this.items.Length);